Archaeozoological analyses suggest sharp differences between Late Byzantine and Early Islamic animal economies, especially in herding patterns and the exploitation of wildlife resources. These differences are suggested to reflect both cultural and land ownership changes following the Arab conquest, against the backdrop of climatic change. The archaeozoological record thereby provides independent evidence to the rise and fall of societal complexity in this marginal region.The Byzantine – Islamic transition (7 CE witnessed the local reverberations of dramatic historical events of the Late Roman, Late Antique (Byzantine), and Early Islamic periods, spanning the rise and fall of the Roman Empire and emergence of Christianity and Islam. At the same time, human communities in this arid and marginal region of the southern Levant variably negotiated unique challenges to the development of settlement, agriculture and trade, against the background of climatic change3. Archaeologists have long aimed to employ the material record of the Negev in order to integrate knowledge of broad historical dynamics with their manifestations in regional and local sequences15. An especially controversial issue centers on explanations of the exceptional fluorescence and subsequent decline of Byzantine-period settlement in the Negev, with researchers differentially drawing on sources of evidence from the historical, material and paleoclimatic records to construct alternative narratives23. Our view of the internal history of the Negev during this crucial period and the way it was impacted by external political, economic and climatic forces remains, however, incomplete: archaeozoological evidences to environmental and cultural change have not received integrative analytic consideration to date.The Negev Desert between the 4th–5th c. CE), which reached a climax in the Middle Byzantine 5th c. CE, marked a singular event in the history of this marginal region2. Through much of the late Holocene, human occupation of the arid Negev involved the presence of nomadic pastoralists, short-term military stations, isolated small-scale farmsteads and trading posts22. This began to change with the Romanization and systemic settling down of Nabataean nomadic trading tribes from the 2nd c. CE17. From the 4th c. CE large-scale expansion of sedentary settlements and agricultural activity in the Negev went together with the establishment of the Byzantine Empire14.The expansion of settlement in the Negev beginning in the Late Roman and Early Byzantine periods  and goat (Capra hircus) herding is generally widespread among mobile pastoralists of the Negev as shown by a range of archaeological and ethnographic studies in this region36. A preference for sheep over goats has been observed in contexts where access to extensive pastureland is relatively unrestricted and production is oriented to urban markets37. In these contexts, specialized producers maintain close relations of exchange with settled consumers who are typically engaged in non-farming activities . Such settled communities would also consume more sheep than goats, since their main source of livestock supplies would be specialized producers, namely nomads31. In contrast, under conditions of sedentary, mixed agropastoral practices we would expect to see less farmer-herder labor division and an increasing preference for goats over sheep. The reason for the preference for goats within sedentary farmers’ strategy of minimizing loss in a worst case scenario is the ability of goats to subsist on degraded, over-grazed pasture36, and also on their high resilience to disease and draught, combined with a high birth rate39. Water shortages in the arid Negev could have limited the use of more water-dependent livestock species , while changing cultural and religious orientations, including the introduction of Christianity and, later, of Islam, could have imposed different sanctions on the consumption of pig (Sus scrofa)41.Models of livestock production and provisioning in systems of nomadic and settled societies predict variable herd management strategies, depending in large part on relations of production in settler-nomad social systems and availability of resources in arid environmentsBecause of the intimate association between livestock management and social organization, more comprehensive understanding of the cultural trajectory of the Negev is made possible by considering the faunal evidence from local sites. The faunal data greatly complement and extend what we know presently from the artefactual record by providing direct evidence on human-environment interactions and the way that these played out through daily social and economic transactions. In this paper we present the first study of a long-term faunal sequence obtained in recent campaigns in four key sites of the Negev, covering the Late Antique-Early Islamic period . This study also uniquely focuses mainly on material obtained from ancient garbage deposits, found both inside and outside of the Negev settlements and shown to contain especially rich concentrations of archaeozoological remains. Employing such a longitudinal approach with a high temporal resolution backed by carbon 14 dating, we show how societies reacted locally to the vagaries of regional politics and the environment while accounting for both the opportunities and limitations of their surroundings. Archaeozoological assemblages chosen for this analysis represent key phases of settlement expansion in the Byzantine and decline in the Early Islamic periods through the Negev sequence  and the Early Islamic (later 7th–10th centuries CE) periods43.The assemblages described in this study were excavated in the central part of the Negev, a desert region in southern Israel. The Negev grades from semi-arid conditions in the North and West to arid conditions in the South and the East, with the excavated sites located in a region which today receives 100 mm mean annual precipitation  and paleo-wetlands around the Dead Sea51 showing a decline in grasses. Other evidences to late first millennium aridification include cessation of west Negev dune formation suggesting a changing wind regime45, high-resolution speleothem analysis from Mediterranean Soreq Cave showing a drying trend unto the end of the 1st millennium CE53, and historical correspondences from the Nessana archives indicating episodes of draught54. To these one might add the cessation of the use of the southern pastures around Makhtesh Ramon following the Early Islamic period55.These shifts comprise of climatic fluctuations of uncertain tempo and punctuality superimposed on a late Holocene drying trend. It is not clear that such climatic shifts significantly affected the arid Negev in Antiquity, but there seems to be a consensus that the Byzantine period enjoyed a somewhat wetter environment, followed by a shift to arid conditions, like the present, toward the later part of the first millennium CE at the latestOur analysis includes faunal assemblages from the following sites56.In late 1999 and early 2000 a large-scale excavation was carried out at the Nabataean Roman site of Avdat in the Negev Highlands by TEG on behalf of the Israel Antiquities Authority. The excavation focused on an area immediately outside and east of the Byzantine town wall, opposite the acropolis. It revealed several sequential dwellings including four rooms of one large Nabataean building constructed in the first century CE, a Roman Nabataean house with a stairway leading to an upper story dated to the late second through early third centuries CE, and several residential buildings constructed in the late third century CE that continued to be occupied until their destruction by earthquake in the early fifth century CE. The faunal assemblages from these different phases were pooled and are interpreted as representing consumption in a Romanized community of Nabataean descent, which subsisted from the Late Roman period onwards on agriculture and tradeIn 2015 an excavation conducted by GBO, LW and TEG on behalf of Zinman Institute of Archaeology at the University of Haifa concentrated on the trash mounds on the periphery of the Byzantine town. Four squares were dug in two excavation areas, located on middens north and south of the town. The accumulated garbage in the middens is from the 5th — early 6th centuries CE and represents organized discard of urban consumption waste in an agricultural and administrative Christian community of the Late Byzantine period. The organized discard of garbage to the extra-mural middens ceased in the mid-6th century, more than a century before the onset of the Early Islamic period in the mid-7th century CE, indicating a change in settlement social organization and/or economy affecting the settlement before the Byzantine/Islamic transition.23. Permanent settlement at Shivta ceased in the 8th century CE.In 2016 YT and GBO conducted an excavation in the village of Shivta. Trenches were dug in 20 different areas at the site. The excavations indicate that the settlement was inhabited already during the later Roman period, although few remains from that period were found. Most of the archaeological finds has been recovered from Late Byzantine 5th — early 7th landfills on the periphery of the village, representing organized garbage management as in Halutza. Fewer finds were collected from the Early Islamic mid-7th — 8th centuries, mainly from household middens that accumulated inside many deserted buildings from the Late Byzantine fluorescence of the town. The population in the Early Islamic period was probably Muslim, as evidenced by an inscription- and cross-bearing lintel stone from a great Byzantine church as a stepping stone at the entrance to a building4 revealed domestic quarters, churches, and an archive of papyri from the 6th–7th centuries CE57. The new excavations were conducted in six areas in the lower part of the settlement, which comprised of both domestic contexts and garbage middens. As in Shivta and Halutza, garbage from the Byzantine period was discarded outside the peripheral wall of the settlement, representing consumption in a Christian, agricultural community. Garbage from the Early Islamic period was dumped inside the precincts of the old town wall, which was already out of use, and inside abandoned Byzantine buildings. The archaeozoological finds presented here were obtained mainly from this later phase, which represents the last years of consumption and discard activity at a neighborhood that housed an ecclesiastical community58.In 2017 YT, GBO, LW and TEG directed an excavation in the town of Nessana, where previous archaeological workFaunal remains of key livestock taxa including mainly sheep, goats, cattle, and pigs were retrieved through on-site hand collection from excavations in the sites of Avdat, Shivta, Nessana and Halutza. Additional systematic collection of remains of smaller species was conducted through dry-sieving of all excavated sediments through a 5 mm mesh in Shivta, Nessana and Halutza. This study is concerned mainly with remains of the large fauna, found almost exclusively in the hand-collected fraction. The analyzed material is stored in the Laboratory of Archaeozoology, University of Haifa to be transferred for long-range storage in 2020 to the Israel Antiquity Authority.Ovis aries, and goats, Capra hircus) were distinguished based on morphological and metric criteria59. Geometric morphometric analysis of two pig lower third molars from Nessana was used to determine if they are of wild or domestic individuals . Caprines . All major livestock taxa show high skeletal completeness and representation of different parts of the animal body, with body-part profiles that are not biased towards any specific element  in all sites, presumably providing a secondary source of meat and eggs75.Although sheep and goat dominate the livestock economies in the Negev during the period in question, other species as cattle, camels and equids are present in the faunal assemblages. Their combined frequencies are quite low, however (<5%). The paucity of cattle likely reflects the difficulty of keeping animals with high water requirements in an arid desert climate. Though equids and camels were kept in the Negev as evidenced by the presence of stables and information from historical textsAn analysis of the tooth eruption and wear-based age-at-death data for caprines shows two distinguishable groups Fig. : one groGazella dorcas, and one horn core fragment to the Mediterranean Mountain Gazelle, Gazella gazella.Game species are represented mainly by gazelles Fig. . In the Two fragments of pig lower third molars from Early Islamic Nessana were compared to a Byzantine domestic pig population, to recent northern Israeli wild boar, and to the isolated wild boar population of the southern Dead Sea using geometric morphometrics (Supplementary Alcelaphus buselaphus) based on ancient DNA. One sample from Halutza (GB24) (dated 540 CE) yielded 100% BLAST Maximum Identity with hartebeest  found only in China, bighorn sheep (Ovis canadensis) found in North America and yellow-backed duiker  found in Central and Westren Africa. All these species had only 90% BLAST Maximum Identity. In summary, the ancient DNA data strongly suggest that the antelope from Halutza was a hartebeest, and not the morphologically-similar Arabian oryx. The sequence has been deposited in GenBank.Additional species include an antelope, that was identified to the species level as hartebeest (Lepus capensis), duck (Anatidae gen. et sp. indet), sea turtle (Chelonia sp.) and crocodile (Crocodylinae sp.)1,with the last two taxa clearly representing imports. The crocodile bone from Shivta , a dermal plate , suggesting perhaps the adoption of local crocodile cults by legionnaires; a contemporary Egyptian text by Athenaeus, however, mentions roasted crocodile as “a most dainty dish”78, indicating that its use was also culinary. The presence in Shivta of a dermal plate rather than a meat-bearing skeletal element may hint at the use of a skin, rather than meat of the animal. Its possible meaning cannot be ascertained and could have ranged from an exotic/expensive status marker to ritual paraphernalia.Crocodiles, widely-worshipped in Egypt unto Roman times are reported to have been imported to Rome and kept in special pools with constructed basking platforms79 (~35%), it departs from documented patterns of archaeological low-intensity gazelle hunting and is on par with data from populations suffering from high levels of hunting pressure in the terminal Pleistocene81.Hunting of occasional gazelles and hartebeest can be understood in terms of both sportive and subsistence activity (Marom and Bar-Oz 2013). Many of the gazelles are young, represented by osteologically immature specimens  replacing a long stable pattern of a sheep-based pastoral economy (SPE) endemic to nomadic Negev herders throughout much of the region’s history until recent times. Additional evidence for these economic transitions comes from data on the age composition of caprine assemblages from the study sites. The Byzantine GPE-type assemblages are also characterized by relatively low frequencies of juvenile individuals, contrasting with more even representation of different age classes as seen before and after this time span. This pattern accords with a generalized strategy of livestock production associated with a sedentary way of life as opposed to more specialized sheep pastoralism, which depend on access to markets for their surpluses as well as requiring more pasture land, water and better quality graze.Our study of faunal remains from the Negev reveals the rise and fall of a sedentary agricultural economy in response to an amalgam of shifting social and environmental circumstances in the Byzantine-Early Islamic sequence. A goat-based pastoral economy (GPE) emerged for a relatively short temporal span during the height of the Byzantine period  with the former adapted to overgrazed pasture near permanent settlements36, and offering sedentising herders added advantages of greater drought and disease resistance. GPE strategies are advantageous where consumption is mainly local rather than market oriented, and mobility is limited. This contrasts with specialized pastoral nomads with an SPE strategy, which target higher market value for their products in times when markets are available, but depend on access to extensive pasture grounds33. Unlike with SPE production strategies for market trade, settled farmers pursuing a GPE strategy are also able to take advantage of the reduced mortality rates of goats compared to those of sheep in the less flexible and more stressed conditions of sedentary communities86. In simple terms, sheep husbandry (SPE), which has prevailed in the Negev for much of its history, requires more human labor, water and land resources and hence competes with agricultural production in sedentary communities87 (Schneider’s88 “Sheep eat men” idiom). Our data suggest that this otherwise resilient strategy among nomadic and flexible herders became temporarily obsolete in the main hubs of settlement of the Negev with the settling down and shifting economic focus of Byzantine communities.We argue for a broadly occurring transition to a GPE strategy of preference for goats over sheep during a restricted period in the Negev’s history in the Early-Middle Byzantine. This transition, which we observe in three different sites with Byzantine assemblages, indicates the establishment of settled agricultural communities where at least a part of the meat supply is grown and consumed locallyA second economic turnaround in the record marks the end of a relatively short-lived Byzantine “experiment” with permanent settlement and agricultural development in the Negev. This transition is observed most clearly in our sequence in the data from a single site. In Shivta, goats are significantly overrepresented in Byzantine period garbage deposits (GPE), whereas material from the Early Islamic period shows the most equitable composition of livestock species in the entire sequence . Similarly, in the Early Islamic assemblage of the nearby site of Nessana sheep and goat are present in comparable proportions, though both are significantly underrepresented relative to other species in this assemblage under a hypothesis of homogeneity with the composition of other assemblages. It is of note that the underrepresentation of goats in this case is more pronounced compared to that of sheep; the frequency of both taxa decreases, but more so of goats.89, also evidenced by the construction of a mosque at this time. Moreover, identification of two specimens of wild boar from Early Islamic Nessana suggests that meat of this species was hunted and consumed.In the Early Islamic period of Nessana we see a sharp departure from the caprine dominated assemblages of all preceding periods in our sequence. Unlike in any of the other assemblages in this site suids, suggested to have been wild boar hunted locally or imported, and wild antelopes (gazelle and hartebeest) comprise the dominant part of the faunal assemblages with significant overrepresentation in the numbers of both taxa. In a contemporary assemblage from Shivta pig frequencies are considerably lower, possibly in relation with a cultural transition from a Romanized, Christian Byzantine community to an Islamic one81. Intensive hunting in the Negev may have brought about the final extinction of hartebeest, which was previously thought to have gone extinct at a considerably earlier time92. This highly atypical subsistence pattern incorporating substantial numbers of pigs, hunted gazelle and wild boar concords with the presence of a spatially-confined economy relying on wild resource exploitation and trade, and Christian rather than Islamic affiliation.These idiosyncratic food preferences in Nessana go along with strong intensification in hunting activities, mainly targeting local populations of gazelle and possibly wild boar. The age profile of hunted gazelles is consistent with a population under severe human hunting93. Transfer of ownership over pasture land to Arab tribes would also explain why sheep and goats are not mentioned at all in the Early Islamic Nessana Papyri22: sheep and goats were not husbanded by the Nessana community. The shift to pastoralism can potentially be observed in the ephemeral nomad settlements of the region, dated broadly by archaeological survey to the Late Byzantine/Early Islamic22. If the pastoral-Bedouin model suggested above is correct, future archeometric dating of these settlements would hypothetically show a clearly Early Islamic (rather than Byzantine) peak.Such conditions could have developed during the land survey conducted in the late 7th century after the establishment of Arab control over the region. This survey that resulted in the allocation of land to Bedouins, who probably used it for pasture. Nessana Papyrus 58 contains a request for tax, to be paid by one Sergius to the governor at Gaza on land given to him for agriculture: the land was transferred to Sergius from an Arab group (Beni Wa’er)The faunal remains from the Negev sequence presented above shows the hitherto unstudied aspect of the livestock management practices that accompanied the Byzantine agricultural florescence of the Negev. These practices focus on goats, which are adapted to sedentary, and therefore resource poor, pastural resource management. This focus on a goat dominated pastoral system stands in contrast to earlier and later desert societies, that endorsed mobility and sheep-based pastoral systems. Additionally, the faunal remains from the dumps of the last Christian community at Nessana suggests a phase of limited access to resources needed for pastoral production. In this last throw of the Byzantine Negev, the Christian community at the site has recourse to intensive exploitation of wild game resources.Supplements


The increased usage of fiber reinforced polymer composites in load bearing applications requires a detailed understanding of the process induced residual stresses and their effect on the shape distortions. This is utmost necessary in order to have more reliable composite manufacturing since the residual stresses alter the internal stress level of the composite part during the service life and the residual shape distortions may lead to not meeting the desired geometrical tolerances. The occurrence of residual stresses during the manufacturing process inherently contains diverse interactions between the involved physical phenomena mainly related to material flow, heat transfer and polymerization or crystallization. Development of numerical process models is required for virtual design and optimization of the composite manufacturing process which avoids the expensive trial-and-error based approaches. The process models as well as applications focusing on the prediction of residual stresses and shape distortions taking place in composite manufacturing are discussed in this study. The applications on both thermoset and thermoplastic based composites are reviewed in detail. Fiber reinforced composite materials have been increasingly used in various structural components in the aerospace, marine, automotive and wind energy sectors. Although manufacturing and investment costs of composite materials are high when compared to conventional materials , their higher strength per unit weight and fewer required machining and fastening operations increase the popularity of composite materials day by day. The direction-dependent mechanical properties of composite materials can also be advantageous in some applications where strength is only required in a specific direction.In the processing of composite materials, the final shape of the composite parts is not the same as the mould shape after the process due to process induced distortions. The basic reason behind the distortion is the process induced residual stresses occurring during the manufacturing process. The nonuniform distribution of residual stresses inside the composite materials results in deformation, matrix cracking, and even delamination. These distortions are represented by spring-in in curved parts and by warpage in flat parts. Problems occur during and after the assembly of parts due to poor contact between mating surfaces unless the magnitude of these distortions are predicted within the tolerances. The assembly of aero-structures especially rigid structures requires matching of smaller sub-components like shims in the assembly phase. Using the sub-components causes the assembly of composite structures to remain a labor-intensive task. On the manufacturing floor, a trial and error approach is preferred to compensate geometrical variations like spring-in angle, but this method is very expensive and time consuming when manufacturing of large components. If the distortions are predicted closely in advance, the investment to the trial and error modification and labor-intensive task during assembly phase can be prevented.The most common problem is that geometrical variations may depend on lay-up, material, processing temperature, tooling geometry etc., which makes the problem more complex. To solve this problem requires more powerful computational models. Increasing the simulation capacity for the manufacturing processes is an important step towards a more cost efficient development and manufacturing of composite structures.Some attractive examples from industry can be given, where the above mentioned problems occur during manufacturing. The 27 m long A350 XWB rear wing spar forms the structural heart of the aircraft wing’s fixed trailing edge,holding vital parts such as the main landing gear. Aileron ribs and fuselage stringers also can be given as examples in the same context. In aerospace applications, the autoclave manufacturing method is used to manufacture these structures. Similar structures can be manufactured using the pultrusion process if the cross section of the structure is constant. Vertical axis wind turbine blades can be an innovative example , 2. Manui) thermal expansion mismatch between the fibers and resin, (ii) chemical shrinkage of the resin during polymerization, and (iii) moisture absorption. The residual stresses at this scale do not cause any distortions of the composite laminate although they adversely affect the strength of the laminate by matrix cracking. The stresses at this scale are self-equilibrating so that they do not lead to large deformations. On the other hand, residual stresses at the macro scale are the source of large dimensional changes. Anisotropic behaviour of individual plies, the constraint effect of individual plies, and tooling constraints are the main sources that trigger the residual stresses at this scale.Developing computational models requires deep knowledge of the mechanisms generating the geometrical variations. In this context residual stresses developed during manufacturing should be examined. Residual stresses can be categorized according to the scale at which they originate and whether they are thermoelastic or non-thermoelastic. Residual stresses can be grouped as micro scale residual stresses and macro scale residual stresses. Micro scale residual stresses develop between the fibers and resin as a consequence of (i) the tool–part interaction, (ii) chemical shrinkage during polymerization, (iii) consolidation, (iv) through-thickness degree of cure or crystallinity gradients, and (v) fiber volume fraction gradients.Thermoelastic residual stresses are reversible so that the distortion can be eliminated by heating the part to its polymerizarion temperature. The source of these stresses in composite materials is the difference between in-plane thermal strains and through-thickness thermal strains. Non-thermoelastic residual stresses, on the other side, are irreversible and the mechanisms behind them are more complex. These mechanisms can be listed as follows –8: (i) tIn the present study, the main mechanisms generating the residual stresses and shape distortions are explained in detail. The state-of-the-art computational approaches are reviewed for modelling the constitutive behaviour as well as the general multiphysics phenomena governing composite manufacturing processes. The interaction between the composite part and the tool is also explained. This work also provides a general overview of the applications of the mechanical process modelling in fiber reinforced thermoset as well as thermoplastic composites. Since the primary focus of this review paper is on the process models to predict the residual stresses and shape distortions during composites manufacturing, phenomena such as intimate contact, bonding, void growth, and polymer degradation and the related models are not reviewed here.Process induced residual stresses and deformations are inevitable during the processing of composite materials and there are several studies carried out in the literature on this particular subject. These studies can be grouped into two basic categories: studies on clarifying the mechanisms behind process induced residual stresses and deformations, and studies on predicting these deformations through different numerical and analytical methods.As mentioned before, it is necessary to have a better understanding of the process induced residual stresses since they directly affect the residual shape deformations which are critical for dimensional tolerances. There are various mechanisms that are responsible for the development of residual stresses and distortions. Thermal anisotropy, chemical shrinkage of the resin, tool–part interaction, resin flow, consolidation and compaction, fiber volume fraction gradients, moisture swelling, prepreg variability, gradients in temperature and the degree of cure or crystallization have all been identified as mechanisms responsible for process induced residual stresses. In the following sections, these mechanisms are discussed in more detail together with corresponding references from literature.The difference between the coefficient of thermal expansion (CTE) of the fiber and resin causes residual stresses on both micro and macro scale; however, this does not cause any distortion on the macro scale . The CTEmentclass2pt{minimThe first attempt to calculate the magnitude of the enclosed angle was proposed by Nelson and Cairns  with theThe development of residual stresses and distortions in unsymmetrical flat , 11 and Radford and Rennick  proposedResidual stresses due to the thermal anisotropy were modelled in –20 by coCrystallization causes shrinkage in thermoplastic composites whereas curing is the main cause of shrinkage in thermosetting resins before cooling. In thermosetting polymers during polymerization, the liquid resin is converted into a hard brittle solid by chemical cross-linking which increases the density and reduces the volume . Resin sWhen the tool or mold and the composite part are forced together by a certain pressure and subjected to a temperature ramp, a shear interaction occurs between them due to the mismatch in their respective CTEs. As this occurs prior to any significant degree of resin modulus development, the shear modulus of the composite part is relatively low. The shear interaction takes place at the tool-part interface, hence the regions in the composite part not interacting with the tool does not experience this shear interaction. This results in a non-uniform stress distribution which is locked in as the resin cures. These stresses cause bending moments upon removal of the composite part from the tooling which leads to shape distortions such as warpage in the composite part. This is illustrated in Fig. Among the large number of multipyhsical phenomena taking place during composite manufacturing processes, resin flow is another important aspect affecting the stress-strain generation. Resin flow affects the distribution of the fiber volume fraction, the mechanical properties of the laminate and the final dimensions of the part . Stress Although the compaction mechanism for curved parts is similar to the compaction mechanism for flat parts, a different mechanism, known as fiber bridging, is responsible for the non-uniform fiber volume fraction in the through-thickness direction. As the thickness of the part is reduced by compaction, the friction between the prepreg layers prevents these layers from conforming to the tool shape at the corner. The applied pressure is ineffective at the corner of the part due to fiber bridging. This creates a low pressure region at the corner of the tool which is then percolated by resin, increasing the thickness of the part at the corner and forming a resin rich region as represented in Fig. Radford  observedHubert and Poursartip  performeThe increased use of fiber reinforced composite materials in different areas encourages manufacturers to produce parts with more complex shapes. This is a difficult task due to undesired defects that often occur during manufacturing. For example, the wrinkling or buckling of plies during the lay-up of prepreg-based multilayer composites, is regularly observed in the corner sections of the L-shaped parts –28. ThesLightfoot et al.  tried toIn order to determine the amount of deformation resulting from the level of fiber wrinkling, a new lay-up method was recently introduced by Cinar and Ersoy . In contTransient heat transfer causes thermal gradients which results in differential polymerization, shrinkage and modulus development of the matrix material in the through-thickness direction and generate residual stresses. Through-thickness temperature gradients are very small for thin parts and can be neglected but for thicker parts, rapid heat generation with the lower thermal conductivity of composite may result in significant temperature and cure gradient . The evoShaping and reshaping of thermoplastics based composites can take place repeatedly, since the network formation of a thermoplastic is purely physical and mainly driven by temperature . In otheT is the temperature, T.Transient heat transfer is an important phenomenon in terms of residual stresses, since it causes thermal gradients which may result in differential vitrification or solidification as aforementioned. Transient heat transfer can in general be modelled using the same principles and approaches for both thermoplastics and thermosetting composite. One of the main differences is the exothermic heat of crystallization as the source term for heat generation in thermoplastic composites as opposed to that of curing in thermosetting resins. The status of the polymer resin changes during polymerization  in which temperature plays a crucial role. The temperature evolution during processing should therefore be evaluated using dedicated thermal models. The heat transfer equation given in Eq. The heat transfer equation provided in Eq. The material properties of the composite part are dependent on the degree of cure or crystallization and the temperature and they are all a function of time and location at any point in the composite part. Since the morphology of the polymer matrix is strongly affected by time and temperature as compared with the fiber material, the analysis of the mechanical properties is performed in two stages. First, the properties of the matrix material such as the modulus of elasticity, shear modulus and the Poisson’s ratio must be predicted given the degree of polymerization  and temperature levels. The properties of the fiber reinforced composite are controlled by its fiber volume fraction and the properties of its constituents together with the fiber architecture, i.e. unidirectional (UD), mat, woven, etc. The effective properties of the fiber reinforced composite can be determined using micromechanics , 44–47. H(t)) during the process to the total heat generated through the complete cure   which caR is the universal gas constant and m and n are the orders of reaction (kinetic exponents). On the other hand, Generally dynamic scanning calorimetry (DSC) tests are employed to determine the polymerization kinetics. Figure rization –57. In grization , 58, 59  systems , 61 sincThe glass transition temperature equation , 63 and arameter , 64:9\doK is a constant, R is the universal gas constant, T is the absolute temperature. A rheometer is utilized to measure the viscosity as a function of time and temperature. Subsequently, a least squares non-linear regression analysis can be performed upon the measured data in order to determine the constants in the viscosity model , It was proposed in , 74 thatn values (between 2.8 to 3.3) for different crystallization temperatures. It was found in [A model based on a single mechanism was used in Cebe et al. ; howeverfound in  that theThus, a model was proposed in  to descrThe complete expression for their kinetic model is :17\documCrystallization shrinkage can be handled in the same way as in cure shrinkage to calculate the shrinkage strains in main material directions in continuous fiber composites by using micromechanics. Another main difference is related to the material models, which depend, besides temperature, on degree of crystallinity in thermoplastic composites and degree of cure in thermosetting composites. The thermal expansion/contraction and chemical shrinkage behavior of the composite are determined using a micromechanics model.The chemical shrinkage of a thermosetting resin can be expressed via the total volumetric shrinkage  flow model for composite materials , 86 baseA number of models have been developed to predict composite resin flow in autoclave processing , 85–91. In this section different constitutive modelling approaches which have been commonly used in literature are presented namely i) the linear elastic model, ii) the viscoelastic model and iii) the path dependent model. The stress-strain relations are presented together with the elastic modulus of the matrix material. It should be noted that the effective mechanical properties as well as the thermal and chemical shrinkage strains for the composite part are calculated using the micromechanics approaches as aforementioned.T of the resin, i.e. The stiffness of the resin significantly depends on the degree of cure  kinetic-viscoelastic model was proposed in  to prediR, respectively. The WLF approach to be used above the glass transition temperature with time-temperature shifting for the retardation time was given according to the expression:The temperature dependency of the retardation time was determined by two approaches: (i) the Andrade (Arrhenius) approach and (ii) The Williams, Landel, and Ferry (WLF) approach. Below the glass transition temperature, the Arrhenius approach was used. The resulting expression for time-temperature superposition of the retardation time is given by:It was noted in  that thea in Eqs. Dynamic mechanical measurements were performed on neat PEEK films showing an increase in the temperature of the maximum in the loss modulus with increasing degree of crystallinity. Their viscoelastic model accounts for this change by varying The dynamic mechanical storage and loss compliance were related to the matrix modulus, The SLS model calculates the elastic modulus of the resin as a function of temperature and degree of crystallinity and in this sense it is very similar to the CHILE model used for thermosetting materials.X), elastic modulus and linear shrinkage strain of a PEEK resin are plotted together with temperature change during the cooling ramp of the process. The degree of crystallinity reaches its maximum value at approximately 7 min after the cooling starts from the process temperature  Eq. .39\documNote that the fiber stresses should be taken into account for the constitutive modeling for thermoplastic composite manufacturing processes since the fiber stresses occur due to draping , 93. Then as in Eqs. The stress and strain tensors are updated at the end of the each time increment t is the current time, T) and degree of cure or crystallization  under consideration be V is written as:S is defined byS at the considered point. This yields in:V is arbitrary, this requires that the integrand be zero:The variation of the stress components as functions of position within the interior of a body is determined in the stress analysis. This can be considered as a type of boundary value problem often encountered in the theory of differential equations, in which the gradients of the variables, rather than the explicit variables themselves, are specified. In the case of stress, the gradients are governed by conditions of static equilibrium. Let the surface traction at any point on a surface Equation Several numerical modelling approaches have been developed to capture the effect of tool–part interactions , 108–114P is the pressure acting normal to the tool-composite part interface. The stick-slip behaviour was determined based on The effect of the tool–part interaction on the distortion has been emphasized in recent studies , 119–130As opposed to the study conducted in  in whichFriction coefficients during the curing were measured in other studies , 130. Mai) dry friction at ambient temperature which was an Amontons-Coulomb-like friction and ii) hydrodynamic friction at temperatures above the melting point of the resin. It was concluded that larger friction surfaces reduced the influence of edge effects and chamfered edges or pulling the metal foil instead of the composite material can minimize these edge effects. Friction experiments were performed in [A friction model was developed in  to prediormed in  on a capIn the extensive published literature, researchers have spent considerable effort to predict residual stresses and distortions in fiber reinforced composites using analytical and numerical methods. An early example of the analysis of the residual stress generation using the laminated plate theory considered only the cool down stage of the process and was only in 1D . DiffereThe CLT was used in the early studies which simulated the autoclave curing process of continuous fiber reinforced composite materials , 134–136Radford  investigWhite and Hahn , 134 devArafat et al. , 111 devFor complex shaped parts, FE analysis has been widely utilized to investigate the process induced stresses and deformations in composite forming processes , 137–141Ersoy et al.  developeZhu et al.  developeA design tool was developed by Cilfford et al.  to prediCinar et al.  extendedool side . The resool side  also peri) a mechanical interaction dealing with the frictional forces, (ii) a thermal contact for heat transfer. The Coulomb friction model with stick-slip behavior was used for the mechanical interaction. A square flat laminate was manufactured to validate the simulations. The predictions and experimental results for maximum distortion and the deformation pattern were found to be in good agreement.An integrated sub-model approach was used in  similar The optimization of a tooling geometry was performed in  to compeSome other approaches were also used to predict process-induced distortions , 142 in In , the proA 3D thermo-viscoelastic model was developed in  to prediThe effects of autoclave curing pressure and cooling rate on the residual shape distortions were studied in  for [\doIn the manufacturing of complex shaped composite parts, the RTM is one of the widely used techniques which involves transfer of resin into a closed mold containing previously laid up dry reinforcement preforms. RTM simulations have been carried out in many studies to predict residual stress and deformations , 148–151Using an incremental approach , 149,curCure-dependent mechanical properties were employed in  using a A 2D semi-numerical model was developed for the process modeling of a relatively thick woven fabric composite plate . The incSvanberg and Holmberg , 66, 67 Mechanical contact constraints were well implemented in a 3D FE model in , 151 to The residual stress development was captured in  by impleDong et al.  developeA state-of-the-art numerical modelling framework was developed by Baran et al.  to prediA UD graphite/epoxy rod was studied in  in whichThe NACA0018 airfoil profile was considered in –157. TheA thermo-chemical-mechanical analysis of the pultrusion process was presented in . A proceA numerical simulation tool was developed to calculate the process induced stresses and dimensional variations in an industrially pultruded L-shaped profile in . The cro The CLT  was emplIn , the resAn L-shaped composite structure was modeled using a 3D thermal-elastic steady state FE analysis in . Thermalinsitu strains were measured suing FBGs during the vacuum infusion process. It was found that the CHILE model overestimated the residual strains when compared with the experimental results which was owing to the time-dependent stress relaxation of the thermosetting system.The accuracy of the CHILE constitutive model was evaluated in  for a siThe earliest process models for thermoplastic composites simulated the processing of parts in an autoclave or hot press , 163 in A rubber press forming simulation was performed using the FE method in  for an AIn , the forProcessing of fiber reinforced polymer composites inherently involves multi-physical phenomena such as resin flow, state changes, heat transfer and solid mechanics. The diverse interrelation between the governing physics makes the process challenging and difficult to control. The presence of residual stresses is inevitable in composite manufacturing processes which might cause process induced defects such as cracking and delamination in the part. When there is a nonuniform residual stress distribution, residual shape distortions are more likely to build up which is not desired since they alter the dimensional accuracy.i) linear elastic model [ii) viscoelastic model [iii) path dependent model [In this paper, the main mechanisms generating residual stresses as well as distortions in manufactured composite parts were reviewed. The necessary modelling approaches containing multi-physical phenomena such as thermokinetics, chemorheology, resin flow with the focus on thermomechanical analyses of the manufacturing processes were presented for thermoset and thermoplastic composites. A general overview was provided for the three different constitutive material models developed in literature: (ic model , 35, (iiic model  and (iiint model . The linnt model . The modnt model .Table 2OThe studies carried out in literature focusing on the modelling of residual stresses and shape deformations occurring during the manufacturing processes were reviewed in detail. It was found that a higher amount of case studies have been applied to thermosetting composites than to thermoplastic composites. Therefore, in the present work, the process modelling studies were grouped based on the utilized constitutive models and specific manufacturing techniques. The corresponding summary is provided in Table The process modelling efforts for predicting the residual stresses and global deformation patterns in composite manufacturing has reached a certain maturity. The research efforts in the future are probably going to focus on the micromechanical or mesomechanical defect formation during the process, e.g., fiber wrinkling , 186, mi


Wastewater irrigation is widely practiced and may cause serious environmental problems. However, current knowledge on the effects of long-term irrigation with wastewater from different sources on the biouptake of trace metals (TMs) in the rhizosphere zone by plants in farmlands is limited. Here, we analyzed wheat rhizosphere soil and wheat roots collected from a typical wastewater irrigation area in North China to evaluate the influence of wastewater irrigation from different sources on the bioavailability of trace metals in soils. Results showed that irrigation with tanning and domestic wastewater helped enhance the bioavailability of trace metals in rhizosphere soil by increasing the active organic carbon content, soil redox potential, and catalase activity, thus enhancing the proportion of the potentially bioavailable part of trace metal speciation. Conversely, irrigation with pharmaceutical wastewater can reduce the bioavailability of trace metals in rhizosphere soil by increasing total soil antibiotics and thus decreasing the proportions of bioavailable and potentially bioavailable parts of trace metal speciation. These findings can provide insights into the migration and transformation of trace metal speciation in soil rhizosphere microenvironments under the context of wastewater irrigation. Wastewater irrigation is a worldwide issue, and it is particularly common in developing countries ,2. This TM contamination has become a severe issue due to its wide reach and persistence in soil over long periods . NumerouRhizosphere refers to the region of soil that is in close contact and interacts with the plant root system within the soil. The microbial activity and chemical conditions of rhizosphere soil, which is a transition zone between soil and plant roots, are sensitive to changes in the external environment ,21. The The main sources of wastewater used for irrigation include domestic and industrial wastewaters . The stoIn this study, we analyzed rhizosphere soil and wheat roots in farmlands irrigated with wastewater from domestic sewage treatment plants, chrome tanning, and pharmaceutical factories in a typical wastewater irrigation area in North China. This study aims to assess the impact of irrigation with wastewater from different sources on the bioavailability of TMs and physicochemical properties of rhizosphere soil.This research was conducted in a cereal crop-producing area of Shijiazhuang, the capital of North China’s Hebei province . The stuShijiazhuang is one of the most important pharmaceutical and leather production bases in China. Certain farmlands in this area have been irrigated with wastewater for more than 30 years as a result of high demand for agricultural irrigation and the simultaneous existence of domestic sewage treatment plants, chrome tanning, and pharmaceutical factories . Three tWastewater-irrigated and reference samples were collected in June 2014 (prior to harvest). Intact wheat roots were randomly sampled at five locations in each farmland. After transportation to the laboratory, rhizosphere soils were collected by using the adhering soil method. Briefly, after gently shaking the wheat roots by hand to remove bulk soils, the soil still adhering to the root surface (2 mm thick at the most) was considered rhizosphere soil. The rhizosphere soil was carefully brushed off from the roots, air-dried at room temperature, and sieved through a 2-mm mesh to remove soil fauna, fine roots, and rock fragments. After removing the rhizosphere soil, the roots were cleaned with deionized water and sealed in plastic bags. A total of 20 wheat root and 20 rhizosphere soil samples were stored at −20 °C for subsequent analysis. The effluents from the local sewage treatment plant, pharmaceutical plant, and tannery all met the integrated wastewater discharge standard of China . Irrigat2  were determined with a Shimadzu 5000 TOC analyzer. Permanganate oxidizable carbon (KMnO4-C) was determined using the method of Vieira et al. , th, th4-C cs of TMs , suggestring-OH) . TherefoOur results also revealed that catalase activity was the dominant factor responsible for the variations in BAF values in the rhizosphere soil a,b. ZengThis study investigated the impact of long-term irrigation with wastewater from different sources on the uptake of TMs by plant roots in the soil rhizosphere microenvironment. Irrigation with tanning and domestic wastewater can led to an enhancement in the bioavailability of TMs in rhizosphere soils mainly by increasing active-soil organic carbon content, catalase activity and soil Eh to increase the concentrations of TMs in the PB part. Active organic carbon content and catalase activity had direct positive effects on BAF values, and soil Eh indirectly affected BAF values by influencing active organic carbon content and catalase activity in farmlands irrigated with tanning and domestic wastewater. Conversely, pharmaceutical wastewater irrigation reduced the bioavailability of TMs in rhizosphere soil by increasing soil antibiotic content to reduce the concentrations of TMs in the PB and B parts. Overall, our results indicate that the effects of wastewater irrigation on the bioavailability of TMs in rhizosphere soils were largely dependent on the source of wastewater. This work provides a new perspective on TM pollution in the soil rhizosphere microenvironment caused by diverse sources of wastewater irrigation. Further studies are required to clarify our findings and their universality in different soil types. In addition, given that tanning and domestic wastewater irrigation may enhance the risk of existing TM contamination, stringent regulations are needed for the irrigations using these wastewaters in the future, especially in developing countries.


The nanomechanics of sarcomeric proteins is a key contributor to the mechanical output of muscle. Among them, titin emerges as a main target for the regulation of the stiffness of striated muscle. In the last years, single-molecule experiments by Atomic Force Microscopy (AFM) have demonstrated that redox posttranslational modifications are strong modulators of the mechanical function of titin. Here, we provide an overview of the recent development of the redox mechanobiology of titin, and suggest avenues of research to better understand how the stiffness of molecules, cells and tissues are modulated by redox signaling in health and disease. Many of the cellular mechanisms of force generation and sensing were first described in muscle and then shown to work similarly in other tissues whose primary function is not mechanical Titin, the largest protein encoded by the human genome , is the paradigmatic example of an elastic protein that works under mechanical force The mRNA coding for titin is alternatively spliced, resulting in muscle-specific isoforms The I-band of titin contains a high proportion of cysteine residues, a major target of redox modifications in proteins 2Oxidative and nitrosative signaling pathways have been described to modulate the mechanical properties of muscle, especially in the heart 2.12O2, increase the stiffness of muscle E. coli-produced titin Ig domains is more challenging Perturbations that lead to formation of disulfides, such as incubation with HMechanically triggered disulfide isomerization has been described to occur in Ig domains containing a disulfide bond and a free cysteine 2.2One of the end products of redox pathways is S-glutathionylation of cysteine residues Interestingly, disulfide formation and S-thiolation of cysteines are interconnected, since S-thiolated cysteines can react with a second cysteine resulting in disulfide formation 3The mechanical properties of muscles must be tightly regulated to accommodate different physiological needs, such as during sleep, light physical activity or strenuous exercise. We are beginning to understand the molecular mechanisms behind this regulation. In this regard, grasping how sarcomeric proteins achieve their optimal elastic output is key to understand the regulation of the mechanical function of muscle.Single-molecule AFM experiments have shown that redox PTMs induce dramatic changes to the mechanics of sarcomeric proteins. Disulfide bonds limit extensibility and lead to protein stiffening Titin contains many domains with clustered cysteines, which most likely form disulfide bonds in vivo Mapping PTMs targeting native titin domains is necessary, but far from sufficient, to understand the complex modulation of titin's mechanical properties. Results so far show that two different kinds of oxidative modifications, i.e. disulfide formation and S-glutathionylation, lead to opposed mechanical effects . It is v4The demonstration that redox signals modulate the nanomechanics of titin opens the way to explore similar effects in other proteins that participate in mechanobiological processes. For example, myosin-binding protein C, a modulator of muscle contraction that works under mechanical load


The complex and elaborate architecture of a neuron poses a great challenge to the cellular machinery which localizes proteins and organelles, such as mitochondria, to necessary locations. Proper mitochondrial localization in neurons is particularly important as this organelle provides energy and metabolites essential to form and maintain functional neural connections. Consequently, maintenance of a healthy pool of mitochondria and removal of damaged organelles are essential for neuronal homeostasis. Long distance transport of the organelle itself as well as components necessary for maintaining mitochondria in distal compartments are important for a constant supply of healthy mitochondria at the right time and place. Accordingly, many neurodegenerative diseases have been associated with mitochondrial abnormalities. Here, we review our current understanding on transport-dependent mechanisms that regulate mitochondrial replenishment. We focus on axonal transport and import of mRNAs and proteins destined for mitochondria as well as mitochondrial fusion and fission to maintain mitochondrial homeostasis in distal compartments of the neuron. Neurons have one of the largest and most complex architectures of all cells in the human body. The peripheral arbors of a neuron can extend for extraordinary distances. In the substantia nigra, for example, the sum total of the axonal arbor may span up to ∼4.5 m . In ordeMitochondrial distribution throughout the neuron is coordinated by microtubule-based transport machinery. This includes an array of motor proteins and adaptors to move  these  organelles  alongDrosophila, these proteins are essential for microtubule based transport of mitochondria into the dendrite and axon  of mitochondria primarily utilizes the Kinesin-1 motor . The attand axon .Retrograde transport  employs a single motor protein complex, Cytoplasmic dynein . Snph acts on the mitochondrial outer membrane (OM) and keeps the organelle stationary by bridging it with the microtubule cytoskeleton. Mice lacking Snph show a significant increase in the motile mitochondrial population . This inKif5A (Kinesin-1 isoform) in ALS patients (Mfn2) gene is one of the most common causes of CMT2A. Expression of disease-associated Mfn2 mutations in vitro results in severe mitochondrial transport defects (p150(glued), a subunit of the dynein activator dynactin, have been associated with motor neuron degeneration and ALS  was found in patients with hereditary spastic paraplegia (HSP), an axonal degeneration disorder of motor and sensory neurons . Additiopatients . Loss ofpatients . Additio defects . Mutatio and ALS . DespiteMitochondrial transport is well-studied in the field of mitochondrial biology and has been elegantly reviewed previously . InsteadSince the somatodendritic compartment contains the majority of ribosomes and the nucleus, for many years it was an attractive hypothesis that protein synthesis occurs exclusively in or near the cell body, with proteins transported to their functional target. This necessitates an efficient mechanism for bringing these proteins to the organelle no matter where it is. Although significant protein synthesis does happen in the soma, relying solely on their long-distance transport is energy expensive for the complicated and extended geometry of neurons and limits the speed with which cells can react to local cues. Research in the past 20–30 years has shown the presence of local translation far from the neuronal cell body in the distal dendrite and axon and, specifically, in pre- and post-synaptic terminals. Local axonal translation is now known to be critical for axonal guidance, synaptic plasticity, growth cone formation, axon branching and maintenance of mitochondrial membrane potential . In addiLocal translation of proteins is likely especially important for mitochondria. This organelle relies on its own mitochondrial DNA (mtDNA) as well as nuclear DNA for proteins that are essential for its function and maintenance. The majority of mitochondrial proteins (∼99%) are nuclear encoded and only ∼1% of them are transcribed from a relatively small, 16.6 Kb circular mtDNA genome in humans . InteresOne mechanism of mitochondrial protein replenishment involves the active transport of mRNAs in RNA granules to mitochondria for local translation. Global gene expression analysis revealed more than one hundred nuclear encoded mitochondrial mRNAs are enriched in axons and pre-synaptic nerve terminals . HeterogProper intracellular transport of the newly transcribed mRNA and the ribosome machinery is essential for local translation. RNA binding proteins help to guide the newly transcribed mRNA to its local translation site in axons and dendrites. Nascent mRNA associate with the RNA binding proteins to form RNA granules. Subsequently the RNA granule is transported along the microtubule track by motor proteins to reach their destined subcellular compartment. In yeast, the RNA binding protein Puf3 was found to interact selectively with nuclear encoded mRNAs for mitochondrial proteins that localize to mitochondria for translation . In mammin vivo the precise function of this process in the biogenesis and maintenance of existing organelles promises to provide exciting advances to our understanding of mitochondrial biology in neurons.Together, the current evidence supports mRNA transport and local translation of at least a subset of mitochondrial proteins in distal regions of the neuron. With the advent of sensitive techniques to study cell type specific local translation While evidence exists for the local translation of mitochondrial proteins, whether this organelle plays a passive or active role in local protein synthesis is a current topic of investigation. One potential role of mitochondria in local protein synthesis, for mitochondrial and potentially non-mitochondrial proteins, is to act as a fuel source. A recent study by Rab7a, which are responsible for Charcot-Marie-Tooth Disease type 2B, caused compromised axonal protein synthesis on mitochondria, impairment of axonal viability along with dysmorphic mitochondria and altered trafficking of the organelle. This study suggests mitochondria can serve as a ‘translational hotspot’ for protein synthesis important for the neuronal integrity and mitochondrial function  proteins which are imported by the mitochondrial IMS import and mitochondrial intermembrane space assembly (MIA) machinery. The MIA40 channel in the inner membrane catalyzes the formation of an intramolecular disulfide bond with the incoming pre-protein which is essential for substrate release in the IMS, stable folding and prevention of reshuffling of the protein back to the cytoplasm .Finally, there are two types of mitochondrial OM proteins which are imported in specific manners: β-barrel and α-helical OM proteins. The β-barrel proteins are transferred to the OM by the standard TOM translocase and small TIM chaperones. Following transfer, the sorting and assembly machinery (SAM) facilitates insertion to the OM. The detailed molecular mechanism of α-helical protein import is not fully understood yet, but previous work suggests at least some α-helical proteins skip the classic TOM translocase and utilize some yet undefined route to the mitochondrial OM  are embryonic lethal (Mfn2 cause Charcot-Marie-Tooth type 2A (CMT2A) disease, characterized by progressive distal sensory and motor neuron abnormalities and distal muscular atrophy  physically interact with the RhoT/Trak complex. Inhibition of ransport . The fis in vivo . In anot in vivo . Recent  in vivo . AlthougProtein synthesis in neurons can occur both at the somatodendritic compartment and at the distal regions of axons and dendrites. Proteins synthesized in the soma need to be faithfully transported through the long length of neuron to the target region or organelle. Additionally, mRNAs can be transported with local translation occurring in distal neuronal compartments. Both mechanisms are utilized by mitochondria and evidence of local translation of mitochondrial transcripts in distal axon has reliably been shown. In either of the above-mentioned scenarios proper axonal transport of these components is essential for mitochondrial survival in neurons. Thus, intracellular transport machinery plays an important role in maintaining the mitochondrial pool along the extended neuronal arbor.Drosophila motor axons where inhibition of Kinesin-1 stops mitochondrial movement in both direction and leads to a dramatic decrease in the density of the organelle (in vivo may aid in the development of effective therapeutics for diseases involving transport defects of this organelle. Future in vivo studies with longer time frames will provide critical insight in to the transport dynamics along the entirety of a neuron.Although the majority of mitochondria are considered to be stationery in mature neurons, at least on time scales of minutes, in order to maintain a healthy pool of the organelle in distal regions, mitochondria rely on active transport. Evidence for this is shown in rganelle . Mutatiorganelle . This imrganelle . Thus, fAM did the literature search and wrote the initial draft. CD directed the manuscript preparation and edited the final version of the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Quantifying the value of investment in medical research can inform decision-making on the prioritisation of research programmes. Existing methodologies to estimate the rate of return of medical research are inappropriate for early-phase translational research due to censoring of health benefits and time lags. A strategy to improve the process of translational research for patient benefit has been initiated as part of the UK National Institute for Health Research (NIHR) investment in Biomedical Research Centres (BRCs) in England. By providing a platform for partnership between universities, NHS trusts and industry, successful BRCs should reduce time lags within translational research whilst also providing an impetus for local economic growth through industry collaboration. We present a novel contribution in the assessment of early-phase biomedical research by estimating the impact of the Oxford Biomedical Research Centre (OxBRC) on income and job creation following the initial NIHR investment. We adopt a macroeconomic assessment approach using Input-Output Analysis to estimate the value of medical research in terms of income and job creation during the early pathway towards translational biomedical research. Inter-industry linkages are assessed by building a model economy for the South East England region to estimate the return on investment of the OxBRC. The results from the input-output model estimate that the return on investment in biomedical research within the OxBRC is 46%. Each £1 invested in the OxBRC generates an additional £0.46 through income and job creation alone. Multiplicative employment effects following a marginal investment in the OxBRC of £98m during the period 2007-2017 result in an estimated additional 196 full time equivalent positions being created within the local economy on top of direct employment within OxBRC. Results from input-output analyses can be used to inform the prioritisation of biomedical research programmes when compared against national minimum thresholds of investment. Economic assessments of the impact of medical research aim to capture the direct health benefits to patients, the health system and wider economy. Direct health benefits following investment in medical research include improvements in patient treatment and diagnosis, advancement of scientific knowledge as well as process changes associated with clinical decision making and health care delivery. Quantifying the value of medical research is an important feature of translational research to inform decision-making on the prioritisation of research programmes. The aim of this paper is to outline a methodology for valuing the return on investment of early-phase translational biomedical research. Existing methodologies on medical research impact are constrained by a paucity of data on direct health benefits during early-phase research as well as time lags associated with the translational research process. We use income and job creation as surrogate outcomes for the economic value of medical research during early-phase biomedical research with censored health benefits.The National Institute for Health Research (NIHR) established the first phase of Biomedical Research Centres (BRCs) in England in 2007 for an initial 5 year period, with the second round of funding initiated in 2012. In the Chancellor’s spending review in the UK in late November 2015, George Osborne protected funding for the third phase of competitive funding for BRCs. The third phase commenced for successful BRCs in spring 2017 as part of the UK Government’s strategy to improve the process of translational research for patient benefit. It is, therefore, timely to evaluate the economic impact of the Oxford BRC (OxBRC). By providing a platform for partnership between universities, NHS trusts and industry, successful BRCs should reduce time lags within translational research whilst also providing an impetus for local economic growth through industry collaboration.A number of methodologies exist for measuring research impact  as an exemplar, we outline the appeal of input-output model multipliers to estimate income and job creation.To capture the value of early phase biomedical research, this paper will focus exclusively on income and job creation following NIHR investment in the OxBRC. To ensure estimates on the return on investment avoid double-counting, we exclude subsequent public research funding secured following the introduction of the OxBRC. Buxton et al.  estimatex represents a column vector of sectoral supply of goods and services, y represents a column vector of inter-industry use of goods and services to produce an output for the respective industry and A is a technology matrix, in this case, derived from the inter-industry transaction table for the South East England economy. The solution matrix following a vector of industry changes in demand from an income injection, y, which ensures inter-industry demand and supply are equalised, can be expressed as:I represents the identity matrix, (I − A)−1 is the inverse of (I − A) and economic coefficients for the input-output model are derived by (I − A)−1  full time equivalent jobs will be supported and created following the initial £98m investment in OxBRC within the economy. This includes the direct employment within OxBRC, indirect jobs created within beneficiary industries of health and education as well as induced job generation from increases in regional income following industry demand and supply changes. After deducting direct OxBRC employment, the marginal effect on employment is an additional 196 full time equivalent positions created following the investment in OxBRC.We present a flexible methodology for estimating the economic impact of early-phase biomedical research. The results on income and job creation from the input-output model signify the OxBRCs role as an engine for economic growth within the regional economy. An additional 196 full time equivalent external positions are created across the region through the establishment of the OxBRC as well as £46m generated by stimulating demand across industrial sectors. The input-output model does not capture additional paybacks, such as population health benefits as well as the generation of external research grant income as a result of the marginal effects of NIHR investment in OxBRC. A key rationale for the focus on income and job creation relates to the role of BRCs as providing a platform for clinical research and industry collaboration for patient benefits. Aggregating NIHR funding to BRC institutions as a means of deriving initial estimates of input for an input-output model would result in inflated estimates of impact. Instead, input parameters should be calculated as the marginal effect of NIHR investment after discounting for existing personnel, equipment, research outputs as well as adjustments for local wage inflation and living weighting allowances. The estimated return on investment for OxBRC can be considered a partial assessment and will require updating once health benefits have come to fruition across the full life cycle of the BRC inclusive of translational lagged effects.The existing payback literature on the value of medical research highlights the disproportional impact of economic benefits in the calculation of rates of return. For example, Buxton et al.  estimateExisting top-down methodologies for valuing medical research may result in over-inflated estimates of impact. Deloitte Access Economics  estimateThere are potential limitations associated with the input-output methodology. Input-output analyses are dependent on the quality of input parameters and magnitude of multiplier effects. The use of national, regional or local economic estimates on supply and use across industries is not without its challenges and limitations. In the absence of local economic input data, careful consideration about appropriate spatial estimates at the national and regional level is needed to ensure generalisability is maintained at the local level. We use Supply and Use data for the South East England regional economy but exclude London as the industry case-mix for London is considered inappropriate for Oxford and, potentially, unrepresentative of the South East England economy as a whole. Results derived from input-output analyses can be considered to be based on deductive reasoning in which historical data on inter-industry linkages are used to predict changes in the local economy. Within this framework, trade between industries in the past is implicitly assumed to be the best indicator of trade in the future. Although this may not appear too strong an assumption, any structural shifts within an economy may result in current trends that deviate from historical patterns of activity. The result following the 2016 UK European Union (EU) membership referendum would fall into this category depending on the nature of the UK’s EU exit in which pre-2016 economic activity may not provide a useful indicator for a post-EU UK. Data collection on local economic inter-industry linkages would be needed in the absence of robust historical Supply and Use tables.The OxBRC is used as an exemplar to highlight the appeal and application of input-output analysis with multiplier effects in estimating the value of early-phase biomedical research. Although the present analysis is confined to the South East England regional economy using a linear deterministic input-output model, the methods are flexible enough to be applied in the evaluation across all NIHR BRCs using dynamic or non-linear input-output methods. If, however, the research question is concerned with the evaluation of all medical research undertaken by a particular funding agency then extensions of the input-output methodology would be fruitful. This may include the adoption of a Social Accounting Matrix and General Equilibrium Modelling methodologies.Existing top-down methodologies for valuing medical research result in over-inflated estimates while microeconomic assessments are constrained by censored benefits. Input-output analysis overcomes these limitations resulting in unbiased estimates while ensuring that the true value of early-phase biomedical research is greater than the sum of the parts. We exclude subsequent public research funding secured following the introduction of the OxBRC to avoid double-counting as some of this activity would have occurred independent of the expenditure on the OxBRC. The results, therefore, represent conservative estimates on the return on investment. As our results are generated using data for the South East England regional economy, the generalisability to differing spatial contexts should apply the top-down methodology using relevant local data. The estimated results of the return on investment for OxBRC exceed the UK Government’s minimum threshold of 3.5% for investments and, therefore, provide economic justification for the continued investment in OxBRC.S1 TableSupplementary Table defining each of the 10 broad industry classifications. The Table is proudced using the “longtable” package in LaTeX and can be viewed as a single .pdf document.(PDF)Click here for additional data file.S2 TableSupplementary Table reporting the technical coefficients for each industry as well as the interdependencies across industrial sectors. The Table can be viewed as a single .pdf document.(PDF)Click here for additional data file.


This review aimed at evaluating changes in alveolar bone thickness after completion of orthodontic treatment. Only prospective clinical studies that reported bone thickness in adult patients undergoing non-surgical orthodontic treatment were considered eligible. MEDLINE, EMBASE and LILACS databases were searched for articles published up to July 2018.  A total of 12 studies met the selected criteria. Most of the studies showed that orthodontic treatment produces a reduction in bone thickness of incisors, mainly at the palatal side.  On patients undergoing different orthodontic treatment techniques, there was a significant bone thickness reduction, mainly on the palatal side.  These findings are relevant and have to be considered in diagnosis and planning of tooth movement, in order to prevent the occurrence of dehiscence and fenestration in alveolar bone.  Evidences show that orthodontic treatment can result in loss of periodontal support in the presence of plaque and inflammation.,,The first attempt to delineate the effect of tooth movement on bone thicknesses concentrated on animal studies.-,Currently it is possible to measure alveolar bone thickness around the roots using the images obtained by cone beam computed tomography (CBCT).Thus, the aim of the present systematic review (SR) is to evaluate the effects of orthodontic treatment on alveolar bone thickness, comparing different types of treatment techniques in adult patients. http://www.crd.york.ac.uk/prospero). The review text was structured in accordance with guidelines from PRISMA  and the Cochrane Handbook of Systematic Reviews of Interventions.The study protocol of this SR was registered at the National Institute for Health Research PROSPERO ; #2: ; #3: ; (#1 AND #2 AND #3). After the initial electronic search, the authors manually searched articles in the bibliographies of the included studies. in vitro studies were not included.Only randomized clinical trials, controlled clinical trials, case series and observational prospective studies with one or more orthodontic treatment arms and tridimensional evaluation of alveolar bone thickness before and after the orthodontic treatment in adult patients were considered eligible for inclusion in this review. Observational studies that included children, patients who had received orthopedic rapid maxillary expansion or accelerated orthodontic treatment such as perforation or corticotomies; studies in which bone thickness was not evaluated using CBCT and studies performed in patients with syndromes and cleft patients were excluded from the review. Further, animal studies, letter to the editors, reviews and Different techniques of corrective orthodontic treatment were considered for this review, among them Straight-wire and Edgewise techniques, and extraction and non-extraction treatments.The primary outcome was alveolar bone thickness change. The alveolar bone thickness was measured on maxillary or mandibular central and lateral incisors, upper canines, upper and lower premolars and evaluated at three different distances  from the cementoenamel junction (CEJ) .Data were extracted independently by two reviewers, and the disagreements were solved by discussion with a third reviewer. Studies appearing to meet the inclusion criteria or those with insufficient information in the title and abstract to allow a clear decision were selected for assessment of the full text, which was carried independently by the same two reviewers to determine study eligibility. Studies that met inclusion criteria underwent a validity assessment and data extraction. The reason for rejecting studies were recorded for each study.Data were extracted and recorded using extraction forms.Risk of bias of the included studies was evaluated according to the Cochrane Collaboration’s Tool for Assessing Risk of Bias. Briefly, the randomization and allocation methods (selection bias); completeness of the follow-up period/incomplete outcome data (attrition bias); blinding of patients (performance bias) and examiners (detection bias); selective reporting (reporting bias); and other forms of bias were classified as adequate (+), inadequate (-), or unclear (?). Based on these domains, overall risk of bias was categorized as follows: (1) low risk of bias if all criteria were met ; (2) unclear risk of bias if one or more criteria were partially met; or (3) high risk of bias if one or more criteria were not met.The methodological quality of the observational studies was assessed using the Newcastle-Ottawa scale (NOS).Initially, 491 references were electronically selected. No additional article was manually identified. After title and abstract evaluation, 436 papers were excluded. The full texts of the remaining 55 publications were considered for detailed reading. Of these publications, 12 were considered eligible for inclusion . ,--,,,,,,,,,,-The characteristics of the included studies are shown in --,Among the 5 clinical trials, only one reported an adequate method of randomization.,-,In the 7 case series, the Newcastle-Ottawa scale (NOS) was used to verify methodological quality (Tab 2). NOS scale was adapted for the purpose of this review, and each included study received a maximum of 14 points. Studies with 9-14 points were considered as presenting high methodological quality; 6-8 points studies, as medium quality; and those with <6 points, as presenting low methodological quality. Of the seven included studies, two received a 7-point score,,,,,Twelve studies assessed changes in bone thickness as a result of the orthodontic movement . Five tr-,,,,Nine studies evaluated central and lateral incisors.,,,35 and one study reported evaluation at 2, 4, 6, 8, 10, 12 and 14 mm from CEJ.Seven studies evaluated bone thickness changes at different distances from CEJ. Three studies evaluated bone changes at 3, 6 and 9mm from CEJ.,,,,,,Regarding studies that evaluated the bone thickness on incisors at different levels from CEJ, only one study found a significant bone loss only at the cervical,-,-Most of the studies showed that orthodontic treatment produces a reduction in bone thickness.In spite of many studies investigating the association of bone resorptions and orthodontic treatment, this is the first systematic review to assess the effects of orthodontic treatment on bone remodeling. Although the 12 selected studies are very heterogeneous, it can be observed that most of the studies showed that orthodontic treatment produces a reduction in bone thickness. No meta-analysis could be performed because the studies included different orthodontic techniques, evaluated distinct teeth with diverse forces. Furthermore, variable treatment times were found.,Studies that performed measurements of bone remodeling without the usage of CBCT were excluded. CBCT enables examination of alveolar bone morphology with quality, since three-dimensional images are not subject to distortion or superimposition.Regarding the specification of the force used in tooth movement, the only authors who reported the measurement of force used in orthodontic treatment were: Nayak-Krishna et al,,,-,,The articles were heterogeneous regarding the type of orthodontic movement performed. As to the treatment plan, some articles reported only alignment and leveling movements,,,,,,,,26 compared self-ligating with conventional brackets, while Cattaneo et al.The heterogeneity of the studies also comprised the type of orthodontic bracket and technique; thus few studies used Straight-wire technique,,-,Regarding the regions where bone changes were measured, the following sites were analyzed: alveolar bone area at cervical, middle and apical levels,The absence or insufficiency of alveolar bone thickness is a complicating factor for orthodontic treatment. The occurrence of dehiscences and fenestrations during orthodontic treatment depends on factors such as: direction of movement, frequency and magnitude of orthodontic forces, volume and anatomical integrity of periodontal tissues.As regards the implications for dental practice, we consider that these findings are relevant and have to be considered not only in diagnosis but also in the planning of tooth movement, in order to prevent the occurrence of dehiscence and fenestration in the alveolar bone. Additionally, it is interesting to notice that the majority of the studies observed a higher percentage of bone remodeling at the palatal side. Probably, the reason for this greater effect at the palatal side is a result of the type of orthodontic movement (retraction of the incisors).On patients undergoing different orthodontic treatment techniques, there was a significant bone thickness reduction, mainly on the palatal side. However, the results should be interpreted with caution, because of the heterogeneity of the included studies.


Lymphoepithelioma-like carcinoma of the bladder (LELCB) is a rare variant of urothelial carcinoma first described by Zukerberg in 1991 and confirmed as a variant of urothelial carcinoma by the WHO classification of tumors of the urinary system. LELCB is characterized by a marked infiltration of lymphocytes in the area involved by the tumor which may coexist with the conventional urothelial carcinoma. LELCB are classified according to the percentage of lymphoepithelioma component within the tumor with the prognosis depending on the percentage. We report a new case of pure LELCB occurring in 63-year-old woman presenting with hematuria. Ultrasonography and cystoscopy revealed a large tumor on the left lateral wall of the bladder. Transurethral resection of the bladder tumor (TURBT) was performed. Pathological and immunohistochemical analysis revealed a high-grade muscle-invasive LELCB (G3pT2). The patient underwent an adjuvant systemic chemotherapy with no recurrence after a ten-month follow-up. To our knowledge, this is the second Moroccan case of LELCB reported in the English literature. Although its rare occurrence prognosis and ideal therapeutic management of LELCB have not been clearly established yet, literature findings encourage the adoption of a conservative approach in treatment of LELCB. Bladder cancer ranks as the ninth most frequently diagnosed cancer worldwide in 2012 with a male predominance. Its incidence is stabilizing or declining in men while some increasing trends are seen for women [This observed evolution of bladder cancer incidence appears to reflect the recently growing contact of women with the causes of bladder cancer such as tobacco and occupational exposures.The most common histological type of bladder cancer is urothelial carcinoma which constitutes more than 90% of all bladder cancers.Urothelial carcinoma has been known to have a remarkable propensity for divergent differentiation which is seen most commonly in association with high-grade and locally advanced disease and which histology is associated with features of biologically aggressive disease .The fourth edition of the WHO classification of tumors of the urothelial tract listed ten variants of urothelial carcinoma differentiation .Lymphoepithelioma-like carcinoma (LELC) is a rare variant of infiltrating urothelial carcinoma first described in the bladder by Zukerberg et al. in 1991 .We herein report a new case of LELC of the bladder with a specific management consisting of a conservative approach even if the tumor was invading the bladder muscle to consolidate literature data.This represents a particularity of lymphoepithelioma-like carcinoma of the bladder (LELCB) with literature data exposing a favorable outcome in patients with LECLB managed conservatively by means of transurethral resection of bladder tumor (TURBT), chemotherapy, or radiotherapy.A 63-year-old patient presents to our department complaining of macroscopic hematuria occurring for 2 months. She had no prior personal or familial medical history of this complaint.An abdominopelvic Doppler ultrasound showed a vascularized parietal lesion of the left lateral bladder wall measuring 2 centimeters with a normal upper urinary tract .A chest and abdominopelvic computed tomography did not find neither hydronephrosis and lymph node involvement, nor a distant metastasis, but a suspected lesion in the vertebral body of D10.The patient underwent a cystoscopy, which revealed a unique non-papillary large tumor of solid morphology, located on the left lateral wall of the bladder. An extensive transurethral resection of the bladder tumor (TURBT) in a single session was performed.Postoperative recovery was uneventful.Histological study revealed a urothelial mucosa infiltrated by tumor proliferation made of nests and ranges of large-sized cells with eosinophilic cytoplasm and frankly atypical and nucleolated nuclei. Muscle layers were also invaded by this proliferation and the tumor stroma was loaded by lymphoid elements .On immunohistochemical study, this proliferation was positively stained by epithelial markers(AE1/AE3) but negatively stained for (CK7 and CK20). The final histopathological diagnosis was pure type of LELCB .For the suspected lesion of the vertebral body of D10 the bone scintigraphy did not find any abnormal results.Magnetic resonance imaging showed high intense signal in T1 and T2 of the D10 vertebral body lesion with important enhancement after gadolinium injection which was in favor of vertebral angioma. That was confirmed by histological findings of a scan guided biopsy of the lesion .A second TURB was performed one month later and did not show any malignancy. A deep resection of the former tumor site was done. Histological examination of the transurethral resection specimen showed a nonspecific inflammatory rearrangement.Since the histological finding shows the existence of pure LELC, the extension study found no other evident locations of malignancy and given that the patient sought organ-conservation approaches and refused radiotherapy fear of its side effects and that her general condition was very good that can withstand systemic chemotherapy, a decision with the oncological department was reached to begin chemotherapy with gemcitabine combined with cisplatin even if the tumor was invading the muscle.Chemotherapy sessions were uneventful. Recent imaging and cystoscopic investigations have confirmed disease remission with no findings suggestive of tumor recurrence.The patient has been under close clinical and radiological follow-up of 17 months without recurrence.The term lymphoepithelioma refers to an undifferentiated nasopharyngeal carcinoma, characterized by epithelial neoplastic cells growing in solid or discohesive sheets intermingled with a prominent lymphoid infiltrate .Carcinomas with similar histological features arising outside the nasopharynx have been called lymphoepithelioma-like carcinomas and have been reported in other organs including the prostate, breast, uterine cervix, skin, lung, trachea, thymus, stomach and salivary glands –8.The reported incidence of LELCB is 0.3%-1.3% of all bladder cancers, with 144 cases reported in the English literature till March 2018.According to a recent exhaustive review of LELCB in English literature published in 2017 by Yang et al. reporting 140 cases of LELCB published between 1991 and 2016 the tumor usually occurs in adulthood with a male predominance. In this review the chief complaint was gross hematuria constantly present. The stage at diagnosis of those tumors was in 87% of cases T2–T3 stage [Till now the exact pathogenesis of this tumor is not well established. Although the association between Epstein-Barr virus and lymphoepithelioma of the nasopharynx and other tissues  is already proved, in the bladder, the hybridization with Epstein-Barr virus encoded RNA has been reported to be consistently negative in different series , 9, 10.Abnormalities of p53 regulation were also suggested for having a role in the pathogenesis of LELCB .Some authors reported the recurrence of urothelial carcinoma treated with BCG therapy in a lymphoepithelial mode without mentioning a link between BCG therapy and LELCB –13.Only Gastaud et al. suggested the role of BCG therapy in the activation of the lymphoid system based on publications of the mechanisms of action of BCG therapy .Differentiation of LELCB from urothelial carcinoma is important, since it has implications for prognosis and treatment.According to the WHO classification criteria, LELCB is defined as a subtype of undifferentiated carcinomas. Histologically, the tumor is composed of nests, sheets, and cords of undifferentiated cells with large pleomorphic nuclei, prominent nucleoli, indistinct cytoplasmic borders, and a syncytial appearance. The background consists of a prominent lymphoid stroma that includes T and B lymphocytes, plasma cells, histiocytes, and occasional neutrophils or eosinophils .Based on the proportion of lymphoepithelioma component Amin et al. described a classification system; tumors are categorized as pure , predominant  or focal , with the three types determining a patient's prognosis .Immunohistochemical stains are helpful in distinguishing between LELCB and its differential diagnosis especially primary lymphoma of the bladder.The particularity of this variant differentiation of urothelial carcinoma is its relatively favorable prognosis compared to pure urothelial carcinoma especially the pure and predominant forms.This has been explicated by several authors who analyzed the lymphoid inflammatory component in LELCB by the importance of the inflammatory infiltrate and cytotoxic T-lymphocytes reflecting the strong immune response against the tumor cells and potentiating the effect of chemotherapy and radiotherapy , 11, 15.Izquierdo-García et al. suggested that the remarkable response of cytotoxic T-lymphocytes in LELCB may be related to a better survival in some tumors and may represent an independent prognostic factor .The sensitivity of nasopharynx lymphoepithelioma to chemotherapy and radiotherapy inspired their use in LELCB.Till now the appropriate management of LELC of the bladder is not unified and as for the other variant of urothelial carcinoma there are no clear guidelines about LELCB.The existing therapeutic procedures are TURBT, partial cystectomy, and radical cystectomy for primary treatments while adjuvant treatments include systemic chemotherapy, radiotherapy, combined chemotherapy and radiotherapy, and intravesical chemotherapy and as reported in the review of Rodríguez-Cabello et al., with a favorable outcome, disease-free survival rate was higher than 80% in the pure and predominant forms confirming their good prognosis .This good result of chemotherapy and radiotherapy in LELCB allowed bladder preservation therapy even in case of locally advanced tumors instead of radical cystectomy that usually involves the uterus in women (anterior pelvectomy) damaging life quality especially in young women.Yoshino et al. reported 13 cases treated with transurethral resection of bladder tumor (TURBT) and chemotherapy: only 9 pure and 2 predominant and 2 mixed  with a mean follow-up of 37 mounts (72-2 mounts) with no evidence of disease when published . This liA variety of chemotherapy regimens have been used MVAC  or GC (gemcitabine and cisplatin), with a promising outcome for platinum-based agents.In the light of the existing data illustrating the good outcome of pure and predominant LELCB even if invasive, salvage bladder therapy including TURBT resecting deep muscle layers and adjuvant systemic chemotherapy can be adopted as the first therapeutic option permitting, especially in women, preserving an intact body pattern and to provide a significant quality of life gain compared to replacement or urinary diversion techniques.Pure and predominant LELCB seems to be a gentle variant of urothelial carcinomaCorrect histological diagnosis specifying the percentage of each component is very important since it has therapeutic and prognostic implications.Chemotherapy is an important therapeutic arsenal in LELCB and should be undertaken, since patients with LELCB present an early onset of symptoms with a preserved state of health enabling them to support systemic chemotherapy.More studies and experiences in the management of this rare urothelial variant are needed to establish clear guidelines of this entity.