Low‐risk differentiated thyroid cancers may, according to the American Thyroid Association (ATA) 2015 guidelines, be managed initially with lobectomy. However, definitive risk categorization requires pathological assessment of the specimen, resulting in completion thyroidectomy being recommended when discordance between preoperative and postoperative staging occurs. This study sought to establish the expected rate of completion thyroidectomy in patients with papillary thyroid cancer (PTC) treated by lobectomy.Patients with PTC treated over 5 years (2013–2017 inclusive) and meeting the ATA criteria for lobectomy were identified from the prospectively developed database of a high‐volume, university department of endocrine surgery. Concordance between the ATA initial and final recommendation, and the putative rate of completion thyroidectomy were calculated. Multivariable analysis was used to assess preoperative factors as predictors of the need for total thyroidectomy.Of 275 patients with PTC who met ATA preoperative criteria for lobectomy there was concordance between this and the final recommendation in 158 (57·5 per cent) and discordance in 117 (43·5 per cent). Most common reasons for discordance were: angioinvasion (30·8 per cent), local invasion (23·9 per cent) or both (20·5 per cent). Four patients (1·5 per cent) had permanent hypoparathyroidism. On multivariable analysis, age, sex, tumour size and family history did not independently predict the final treatment required.Although many patients may be treated adequately with lobectomy, just under half would require completion thyroidectomy. Further work is needed on preoperative risk stratification but, before this, total thyroidectomy remains the treatment of choice for low‐risk 1–4‐cm PTC in the hands of high‐volume thyroid surgeons who can demonstrate low complication rates. The incidence of differentiated thyroid cancers (DTCs) has increased in recent decadesThe American Thyroid Association (ATA) guidelines of 2015Proponents of more conservative surgical approaches cite the need to account for differing complication rates from surgeons of all skills sets as reasons to change guidelinesPTC comprises 85 per cent of all DTCs and is associated with the best prognosis for all thyroid cancer subtypesFollowing appropriate ethical review board approval, data were drawn from the prospectively developed database of consecutive patients undergoing surgery in a university teaching hospital department of endocrine surgery performing over 1500 procedures  per annum. All patients with PTC whose preoperative risk factors would have rendered them suitable for lobectomy according to the 2015 ATA guidelines 35(B)BRAF V600E mutation or microscopic extrathyroidal extension was not considered an indication for total thyroidectomy.Patients were diagnosed using fine‐needle aspiration biopsy, and staged by an endocrine surgeon based on clinical examination and imaging with one or more of ultrasonography, CT or MRI. Routine prophylactic ipsilateral central compartment dissection (pCND) was performed in all patients, based on the potential for reduction in the rate of local recurrence and avoidance of reoperation as set against a low morbidity for the procedure in this unitAll patients in the database with a final diagnosis of PTC were included, and suitable patients selected using the following exclusion criteria: tumour size less than 1 or greater than 4 cm, invasion into surrounding structures, clinical or radiological lymph node metastases, and Bethesda I–IV aspiration biopsy result.The primary outcome measure was concordance between the ATA 2015 initial recommendation for lobectomy and the final recommendation based on histopathology: no further surgery or completion thyroidectomy. The presence of histological features leading to an intermediate‐risk classification according to the ATA 2015 guidelinesA secondary analysis was performed to establish whether any preoperative factor was able to predict the requirement for completion thyroidectomy. Preoperative factors assessed were age, sex, family history and tumour size.versus rate of completion thyroidectomy. The secondary analysis was performed using simple bivariable correlation and multivariable logistic regression. All statistics were calculated in SPSS® version 24 .The demographics and primary outcome measure of concordance between the ATA 2015 initial and final treatment recommendation were expressed using simple descriptive statistics: median (range), and percentage concordance Fig. Some 750 patients who underwent thyroidectomy between 1 January 2013 and 31 December 2017 were diagnosed with PTC as the primary pathology on histology. Median age in this low‐risk group was 51 (range 19–84) years and 228 patients (82·9 per cent) were women. Median tumour size was 15 (range 10–35) mm. Total thyroidectomy and central compartment lymph node dissection was performed in 253 patients (92·0 per cent). Patients were counselled routinely about the option of undergoing hemithyroidectomy and the possibility of further completion surgery being required. Some 8·0 per cent chose to undergo hemithyroidectomy. Prophylactic central lymph node dissection was also performed in these patients.Fig. Analysis of the final histopathology of these 275 patients showed concordance between the initial ATA recommendation for lobectomy and final recommendation in 158 (57·5 per cent), but discordance, representing a requirement for completion thyroidectomy, in 117 (42·5 per cent). Features that would have attracted the recommendation for completion thyroidectomy are shown in Complication rates were low. A single patient developed a haematoma requiring surgical evacuation, there were eight temporary palsies of the recurrent laryngeal nerve (2·9 per cent) and two recurrent laryngeal nerves were sacrificed owing to involvement with advanced tumours (both T3 N1a). There were no inadvertent permanent recurrent laryngeal nerve injuries. All patients were managed with prophylactic oral calcium in the immediate postoperative period, with four developing permanent hypoparathyroidism (1·5 per cent).There were three local recurrences in the cohort. These included two patients who would have been stratified as low risk and potentially offered hemithyroidectomy according to the ATA guidelines, and one stratified as intermediate risk. One of the low‐risk patients underwent hemithyroidectomy as the initial surgery and subsequently required completion thyroidectomy.Fig. R = 0·105), but this was not statistically significant (P = 0·081). No statistically significant correlation was found between the final recommendation and any other variable. All variables were then entered into a multivariable logistic regression model; again, age came the closest to statistical significance  but no statistically significant independent predictor of the need for completion thyroidectomy was found.The change in guidelines away from total thyroidectomy to lobectomy has been a topic of much debate for several reasons. Interpretation of the data that led to the change has been questioned. Emphasis on survival as the primary outcome measure neglects the issue of local recurrence; this is arguably of greater importance in lower‐risk cancers as there is concern that, in a bid to avoid potential overtreatment, the reverse will occur. Even if survival is not significantly affected, an increase in local recurrence may be seen in the coming years. The logic of avoiding complications by reducing the extent of surgery loses sight of the fact that complication rates differ between low‐ and high‐volume surgeons. Finally, reoperation for completion thyroidectomy in the short term and reintervention for local recurrence in the longer term may nullify any benefit from avoidance of immediate complications.The change in ATA guidelines was based on studiesProponents of lobectomy cite the avoidance of serious complications  and obviation of the need for lifelong thyroxine as justification for this approachversus total thyroidectomy in the future.The advocacy for total thyroidectomy is linked to administration of iodine‐131, facilitation of monitoring with serum thyroglobulin (TG) and analysis of the contralateral thyroid lobe for other foci of disease. Although the benefit of iodine‐131, whether for remnant ablation or cancer therapy, has been shown in an unselected retrospectively analysed cohortThe use of serial serum TG measurement for post‐treatment monitoring has been debated. Although pCND does not necessarily increase the rate of athyroglobulinaemia, TG is certainly not a meaningful marker in the presence of a remnant lobeAnalysis of the contralateral lobe for occult carcinoma is another potential benefit of total thyroidectomy. Rates as high as 47 per cent have been reportedThe rate of completion thyroidectomy in this study was over 40 per cent, more than twice the 19·5 per cent rate in the cohort study of all DTCsVariability in the expected rate of completion thyroidectomy and complications specific to an individual unit and surgeon highlight the difficulties in creating guidelines to cater for DTC managed in diverse settings. It is admirable that the ATA has sought to protect patients from the complications of unnecessary operations; however, using guidelines to encourage the low‐volume surgeon to perform a lower‐morbidity operation for DTC is only one way to achieve this. This study highlights the importance of surgeons understanding the characteristics of their own patient cohort, their individual complication rate and patient attitudes towards completion thyroidectomy, along with complications in each scenario and implications of lobectomy or surveillance, when selecting the most appropriate surgical option in low‐risk patients.In the future, preoperative molecular analysis may assist in more accurate preoperative risk stratification and decision‐making but, in the meantime, guidelines such as those provided by the ATA should be applied flexibly to reflect differing circumstances of providers and patients. Further work on decision analysis based on the relative merits of the two approaches and patient preference may also be of benefit


WHO/CDC Logic‐Model for Micronutrient Interventions in Public Health was used as an organizing framework for analysing and presenting the evidence. Our findings suggest that to successfully implement supplementation interventions and achieve sustainable‐permanent solutions efforts must focus on factors and processes related to quality, cost‐effectiveness, coverage, utilization, demand, outcomes, impacts, and sustainability of programmes including strategic analysis, management, collaborations to pilot a project, and careful monitoring, midcourse corrections, supervision and logistical‐support to gradually scaling it up.Micronutrient deficiencies during pregnancy pose important challenges for public‐health, given the potential adverse outcomes not only during pregnancy but across the life‐course. Provision of iron‐folic acid (IFA) supplements is the strategy most commonly practiced and recommended globally. How to successfully implement IFA and multiple micronutrient supplementation interventions among pregnant women and to achieve sustainable/permanent solutions to prenatal micronutrient deficiencies remain unresolved issues in many countries. This paper aims to analyse available experiences of prenatal IFA and multiple micronutrient interventions to distil learning for their effective planning and large‐scale implementation. Relevant articles and programme‐documentation were comprehensively identified from electronic databases, websites of major‐agencies and through hand‐searching of relevant documents. Retrieved documents were screened and potentially relevant reports were critically examined by the authors with the aim of identifying a set of case studies reflecting regional variation, a mix of implementation successes and failures, and a mix of programmes and large‐scale experimental studies. Information on implementation, coverage, compliance, and impact was extracted from reports of large‐scale interventions in Central America, Southeast Asia, South Asia, and Sub‐Saharan Africa. The  The IACS was developed and gradually improved, as part of a National Micronutrient Plan, with IFA supplementation to pregnant women provided as a part of a comprehensive approach including other strategies for anaemia control such as flour fortification; behavioural change communication (BCC); target‐training to health service and non‐governmental organization (NGO) personnel and community health volunteers; and development of a system for programme monitor and evaluation.The key programme characteristics are listed in The Iron Intensification Project within the Nepal National Plan of Action for the Control of Anaemia is an example of strong partnership with international non‐governmental agencies and organizations supporting IFA supplementation plus deworming to pregnant women as part of the ante‐natal care services. Detailed documentation is available. The Iron Intensification Project was developed and implemented by integrating activities aimed at improving intervention access via distribution of supplement and counselling supported by female community health volunteers; strengthening complementary measures such as dietary promotion and fortification at national level; providing high‐quality training; establishing intensive monitoring and supervision ; Information, Education and Communication (IEC) to create awareness of the role of iron in foetal growth and perinatal mortality; operational research on food biscuit and fish‐sauce fortification with other micronutrients and deworming for nonpregnant women.The programme features are outlined in 3.2.2These studies were chosen as examples of operational research investigating the effectiveness of specific delivery‐platforms such as community‐based nutrition programmes, health system platforms integrating nutrition interventions, and/or market‐based interventions at achieving either process or impact outcomes. These one‐year pilot‐effectiveness projects were conducted jointly by Department of Health and United Laboratories (UNILAB), the Philippines' largest private pharmaceutical company, with the support of the WHO Regional Office for the Western Pacific. “Social marketing” was applied as a framework to be applied for selling and dispensing preventive‐IFA to women of reproductive age by community workers, and motivating them to both adopt and maintain the behaviour for a long period of time. These studies followed national nutrition surveys on the prevalence of anaemia among pregnant women. A master protocol was developed and adapted in each study based on contextual elements and rapid situation assessments, in order to study impact and processes of implementing a weekly‐supplementation approach in countries with high anaemia rates but different socioeconomic systems and cultures. Pregnant women were given pregnancy‐targeted UNILAB tablets free of charge until the 3rd month after the delivery, then were expected to purchase the UNILAB supplements specifically target to nonpregnant women. In Philippines, pregnant women were delivered with a monthly dose either at prenatal check‐ups in local health units or at home visits by a responsible trained volunteer health‐worker or midwife, whereas nonpregnant women could buy their specifically targeted supplements at the drugstore or directly by the local health staff. In Vietnam, nonpregnant women could buy their specifically targeted UNILAB tablets from Women's Union collaborators. Four surveys were conducted to evaluate Knowledge, Attitudes and Practices (KAP) towards anaemia and IFA tablets, and to collect haematological parameters with haemoglobin, ferritin, and soluble transferrin receptor being assessed by national institutes.A part from an overall enhancement of iron status, the most salient results of these pilot studies  were theThe Supplementation with Multiple Micronutrients Intervention Trial (SUMMIT) aimed to compare benefits of MMN versus IFA supplements on maternal and child health, and was designed as both a programme and research trial. Drawing on community‐based participatory methods in conjunction with iterative evidence‐based implementation enhancements, SUMMIT attempted to enrich outputs and improve overall impacts. Early formative research on existing health care delivery and health‐seeking patterns preceded the project design.Project outcomes  includedThese pilots evaluated the impact on anaemia of preventive‐IFA supplementation combined with other health interventions within women of reproductive age.Following a baseline survey, in two‐districts of a northern Vietnamese province a pilot project was established to make preventive‐IFA supplementation and regular deworming treatment freely and universally available for all women of reproductive age. Results  showed tThe MICronutrients And Health (MICAH) programme was a NGO‐led large‐scale, multicountry, 10‐year programme led by World Vision Canada with funding from the Canadian International Development Agency to reduce prevalence of micronutrient deficiencies in women and children. It was implemented in five African countries. In Ghana, anaemia strategy focused mainly on improving iron intake by supplementation whereas, in contrast with the other MICAH countries, minor emphasis was put on preventing malaria and hookworm due to the low malaria prevalence at baseline. Results  showed t4WHO/CDC Logic‐Model for Micronutrient Interventions in Public Health framework to evaluated programmatic components and subcomponents (what), we identified and summarised the actions and methods (how) which contributed to success in coverage, compliance, and impact within the selected case studies.Micronutrient malnutrition persists among pregnant women in many countries not only because the causes of under‐nutrition may be not successfully addressed  and understanding which capacities needed to be developed. These actions have been highlighted as crucial to align efforts and actions, and to accelerate progress towards improved nutrition‐health outcomes  were key activities highlighted within the set of case studies we reviewed. Establishing monitoring systems for all activities, through which accurate information flowed from the community up to the national level, resulted crucial to allow strategic solutions to be taken at the appropriate level in a timely manner. Efforts were put to support rigorous and continuous monitoring and communication on project progresses from both health‐workers and/or community agents to project‐technical responsible and from project‐team to commune/village/organization leaders. This allowed on one hand the constraints to effective implementation to be indentified and emended, on the other the community interest and commitment to be maintained. Furthermore, documenting impact and performance indicators on a regular basis, mostly by the means of external quality control systems, meant producing strong, and consistent evidence of on‐going effective implementation to confirm a gradual scale‐up. Evidence‐based approaches included surveys and analyses at programme baseline, midterm and the close concerning nutrition and implementation indicators of integrated package of interventions. Indeed, the adequacy evaluation of the MICAH programme .Appendix A: Program key‐characteristics gathered according to a simplified version of the Click here for additional data file.


Performance degradation is one of the key obstacles limiting the commercial application of organic photovoltaic (OPV) devices. The assessment of OPV stability and lifetime are usually based on simulated degradation experiments conducted under indoor conditions, whereas photovoltaic devices experience different environmental conditions under outdoor operation. Besides the intrinsic degradation of OPV devices due to the evolution of optoelectronic and morphological structure during long‐term operation, outdoor environmental changes can impose extra stresses and accelerate the degradation of OPV modules. Although outdoor studies on long‐term OPV stability are restricted by the long data collection times, they provide direct information on OPV stability under mixed degradation stresses and are therefore invaluable from the point of view of both research and practical application. Here, an overview of the current status of outdoor lifetime studies of OPVs is provided. After a summary of device lifetime extrapolated from indoor studies, outdoor lifetime testing platforms are introduced and the operational lifetime of various OPV devices are reviewed. The influence of climate and weather parameters on device performance and burn‐in phenomena observed during the degradation of OPVs is then discussed. Finally, an outlook and directions for future research in this field are suggested. Through the combined effort of chemical design and synthesis, new polymer donors and nonfullerene organic semiconductor acceptor materials have emerged and enabled numerous photovoltaic blend systems to achieve power conversion efficiencies (PCE) in excess of 10%;The degradation of OPV device performance has been widely observed, however the volume of research undertaken to study this process is substantially less than that devoted to the development of new materials or processing studies undertaken to engineer an enhancement in PCE.Compared to outdoor studies, lifetime studies conducted under indoor conditions combine the advantages of reduced data collection time together with well‐controlled and well‐defined environmental conditions. However the degradation pathways that exist during indoor studies are usually fixed rather than evolving dynamically, and thus outdoor lifetimes cannot be easily predicted by linear extrapolation of different degradation factors. Rather, outdoor lifetime testing can directly provide information regarding OPV module stability under real world conditions that change dynamically.In this review, we start with a brief introduction to indoor lifetime testing. Following this, long‐term outdoor lifetime setups are introduced, with a comparison of outdoor lifetime studies on a series of OPV devices presented. We focus on factors that have been found to affect OPV degradation, including temperature, irradiance level, humidity, and thermal cycling. Morphological and optoelectronic contributions to device burn‐in and recent reports of burn‐in free systems are also discussed.2Outdoor real‐world lifetime studies of OPVs are time consuming and require a comprehensive testing platform. Because of this, the lifetime of OPV devices is usually extrapolated from indoor degradation tests that are run under accelerated conditions.Before 2011, there were no specific standards for OPV lifetime testing, and thus the results reported before then cannot be fully compared due to differences in data collection, analysis and presentation methods. At that time, the standards used in some OPV lifetime research were based on protocols developed by the International Electrotechnical Committee (IEC) for the characterization of amorphous silicon PVs. Here the most commonly used standard is known as IEC61646 which comprises a series of degradation tests, including a 1000 h damp heat (DH) test at 85 °C and 85% humidity, 200 cycles of thermal cycling (TC) from −40 to +85 °C, and a sequence test consisting of UV exposure, 50 cycles of TC, and 10 cycles of humidity freeze (HF) from −40 to +85 °C at 85% humidity. After finishing each test, modules are then characterized to determine device efficiency.The feasibility of applying the IEC61646 standard to OPV lifetime testing has been explored. For example, Yan et al.TableOPV lifetime testing conducted under laboratory conditions can be divided into several conditions, with devices being subjected to dark storage, laboratory‐weathering, thermal‐cycling and solar‐thermal‐humidity cycling. For each test, three levels are defined according to the requirements for measurement facilities and accuracy, as shown in Dark storage and laboratory weathering tests are two widely used long‐term lifetime tests that are conducted indoors. Thermal cycling and solar‐thermal‐humidity are rarely applied due to the relative complexity of the tests as well as the short lifetime of most OPVs under such harsh conditions.TableIn dark storage tests, OPV devices are simply stored in the dark, with the exposure to atmospheric oxygen and moisture being the main degradation processes. According to ISOS test protocols, devices can be exposed to ambient or elevated temperatures and humidity, with tests corresponding to ISOS‐D‐1, ISOS‐D‐2, and ISOS‐D‐3 tests as described in Table Another commonly used laboratory method to predict OPV lifetime is exposing devices to a constant irradiance, known as laboratory‐weathering tests. It is generally found that device lifetimes measured under dark storage are much longer than those measured when devices are irradiated. For some photosensitive organic semiconductors, e.g., PBDTTT‐EFT,FigureA typical schematic of OPV efficiency as a function of time is shown in Admittedly, in some cases the accurate determination of this point is not straightforward; however, in long‐term lifetime studies, the inaccuracy introduced by this uncertainty is relatively small. Sometimes the lifetime parameter T80 is quoted which is defined as the time over which the efficiency decays to 80% of its initial value. Clearly, Ts80 is longer than T80, as sometimes more than 20% of initial efficiency is lost during the burn‐in period. In many cases the T80 lifetime can be relatively short, however this does not necessarily result in a short Ts80.−2 (±4%) and a temperature of 37 °C (held using a water heated copper plate) over a period of 4400 h. For both types of device, a clear burn‐in period was observed lasting around 1300 h. Using a linear fit, a Ts80 lifetime of more than 12 000 h was extrapolated for PCDTBT based devices. It was also found that a clear determination of the end of the burn‐in period was critical in extrapolating the Ts80 lifetime. In theory, the end point of the burn‐in process should correspond to the turning point of the slope in the degradation curve after which efficiency degrades in a linear manner. However, identifying this point is subjective and a consensus should be established and applied to precisely define this end point. Indeed, by changing the end of the burn‐in process, the extrapolated Ts80 lifetime of P3HT based devices was varied from 5000 to 7000 h. Under the assumption that a PV device positioned outdoors would be exposed to an average irradiance level of one sun for 5.5 h day−1, a lifetime of 6.2 years and between 2.5 and 3.8 years was predicted for PCDTBT and P3HT based OPV devices respectively. Despite the relatively large errors that are associated with such extrapolations, a predicted lifetime of 6.2 years is an encouraging level of OPV stability. Furthermore, by minimizing oxygen and water exposure during the test conditions, Mateker et al.The lifetime of an OPV module can be estimated by calculating the energy dose received by a module under indoor conditions. This is then converted to an equivalent energy dose that would be received from the sun under outdoor conditions. Peters et al.FigureY‐axis of the o‐diagram represents the initial efficiency of an OPV module  and the X‐axis represents device lifetime plotted on a logarithmic scale. A second time‐scale presented at the top of the diagram divides time into hours, days, weeks etc. This presentation method is an effective way to compare device lifetimes obtained under different test protocols.In some reports, device stability has not been estimated based on a single test, rather researchers have used a series of protocols to investigate the degradation of OPV devices. This raised the question of how to compare the lifetime data acquired under different protocols. Gevorgyan et al.TableRecently, Kettle et al.This work allowed lifetime data collected indoors under different ISOS standards to be related to expected lifetime under outdoor conditions. However, this model is clearly dependent on local climate conditions in North Wales and cannot provide a universal model to transfer indoor lifetime data to outdoor results. Indeed, due to the large variations in real‐world conditions, the establishment of a general model is not trivial. However, one possible solution is to determine a coefficient for each parameter; this will clearly require international coordination and collaboration together with considerable financial investment.3TableConsidering the difficulties in simulating outdoor real‐world conditions for OPV lifetime tests, a number of researchers have explored moving such tests directly to outdoors. Indeed, outdoor lifetime tests are also included in the ISOS standard, as shown in 3.1FigureTo study OPV degradation outdoors, it is necessary to build a reliable testing platform. Such studies have been pioneered by F.C. Krebs and his colleagues, who have made strong progress in this area. In 2006,J–V measurements. Here, the setup fulfilled all requirements of ISOS‐O‐2 although it was reported prior to the establishment of the ISOS standards.In 2008, researchers from Konarka Inc.FigureJ–V curve every 10 min (and held at open circuit between measurements). Along with the device metrics, the system recorded environmental parameters including temperature and irradiance level. The OPV modules were intermittently dismounted from the platform and tested under a solar simulator to fulfill the requirement of ISOS‐O‐3. Their collaborators also built outdoor lifetime testing platforms in India, the Netherlands, Germany, Australia and Israel, which were simplified versions of the system in Denmark while still fulfilling ISOS‐O‐2 standards.After the establishment of the ISOS standards, Krebs and co‐workers built a test platform located in Roskilde, Denmark (55.6°N). As shown in FigureJ–V curves were recorded at an interval of ≈5 min, with temperature and irradiance measured simultaneously. The sample chambers were held at an angle of 30° to the horizon and pointed south to maximize the solar flux incident upon the OPVs. Because of the use of the sample chamber however, this platform does not fulfill the requirement of ISOS‐O as the devices are no longer directly exposed to air or moisture. This is because the chamber does not form part of the device and cannot be considered as extra encapsulation. Nevertheless, it does allow long‐term comparison to be made between different organic‐semiconductor devices that have imperfect encapsulation.Another outdoor lifetime testing platform was built in Sheffield, England (53.4°N).FigureVoc) and short circuit current (Jsc). The development of this suitcase enabled comparable outdoor test experiments to be performed by most research laboratories and increased participation in the “OPV outdoor testing consortium”.As the climate and geographical conditions significantly influence the performance and degradation of OPVs, it is useful to compare degradation of OPV modules located in different regions to explore the effect of climate on their long‐term outdoor stability. Krebs et al.J–V sweeps, temperature and irradiance level. Such systems are also portable and sufficiently inexpensive to be accessible to research groups having a limited budget. The establishment of such a test platform would require concerted action from the whole OPV research community.In summary, a number of successful long‐term outdoor lifetime testing platforms have been developed, however, a universal, cost‐efficient setup is still needed. The general requirements for such a platform include methods to automatically and continuously record 3.2According to the database of ISI web of knowledge, a search including the key words “organic/polymer solar cells/photovoltaics,” returns more than 14 000 hits. However, when the key word “outdoor” is added to the search, only around 150 hits are found. Furthermore, the majority of OPV outdoor lifetime studies only last for a few hundred hours, with long‐term outdoor lifetime tracking studies being relatively rare.2O5·0.5H2O HTL had good stability in outdoor conditions, with the use of a UV filter being beneficial in improving device stability (UV irradiance can induce photoreactions and thereby reduce device performance). A similar study was conducted by the same group,2O5 hole transport layer could improve P3HT:PCBM based OPV module lifetime, with devices still retaining more than 80% of their initial efficiency after 900 h of continuous testing. Josey et al.−1 and were returned to indoor conditions for dark storage at night, and thus this study cannot be directly compared with other work.Although short‐term outdoor lifetime testing cannot be used to extrapolate the long‐term lifetime of OPV modules, it is an effective tool to compare the influence of different designs on OPV stability. For instance, Teran‐Escobar et al.TableMost outdoor studies have been conducted by Krebs and co‐workers, with a particular focus on P3HT:PCBM based solar modules fabricated by roll‐to‐roll processing methods. Their outdoor lifetime studies have been performed in different counties including Denmark, India, Holland, Germany, Israel, and Australia. The details of their results are presented in The lifetime of OPV devices is significantly affected by the quality of the encapsulation;−² day−1.As can be seen from Table It has been argued that low OPV module efficiency is not an obstacle for commercialization providing that devices cover a sufficiently large area and that manufacture cost is sufficiently low.(1)To ensure the reproducibility and reliability of the lifetime data, at least 5 identical devices should be measured under the same conditions.(2)The environmental conditions including temperature, humidity, and irradiance level should be monitored and recorded along with OPV device metrics.(3)The cumulative energy dose received by the samples should be calculated over the whole test period.(4)Samples should be periodically taken back to laboratories and tested under well‐defined indoor conditions (at least once a month is recommended). This is especially necessary in winter or in rainy seasons when irradiation is limited. However, mechanical and electrical stresses during such indoor tests should be carefully controlled and minimized.(5)Jsc should be normalized to the irradiance level to make a fair comparison.As the irradiance level has great influence on the device efficiency, the data collected should be screened according to specific irradiance level range. The (6)If possible, the efficiency and temperature coefficient of the device should be established and the PCE should be corrected according to this coefficient.(7)A direct link between the ISOS‐L and ISOS‐O lifetime tests should be established via the cumulative energy dose received by the devices,The adoption of ISOS‐O standards clearly results in compatibility between tests conducted by different research groups. Although such ISOS‐O standards are detailed, Gevorgyan et al.[[qv: 33b]] made a series of further suggestions and supplements to such measurements that we summarize here:4The environment is a dynamic system, with temperature, humidity and irradiance levels all changing simultaneously over time and over seasons. In the following sections, we discuss how these factors influence OPV lifetime.4.1Jsc) usually increases with elevated temperature. The open circuit voltage (Voc) decreases slightly with increased temperature,The efficiency of OPVs is strongly dependent on temperature, as charge transport in organic semiconductors occurs through a thermally‐assisted hopping processne and nh are the electron and hole densities in the acceptor and donor domains at open circuit, and Nc is the density of conduction states (DOS) at the band edge of the acceptor and donor. The overall device efficiency most often increases due to a stronger positive correlation of Jsc with temperature. It has been shown that the efficiency of ITO/PEDOT:PSS/OC1C10‐PPV:PCBM/Al OPV devices increases from below 0.8% at 250 K to 1.9% at 320 K as shown in Figure70 OPV devices in outdoor conditions suggested that the positive temperature coefficient resulted from spectral broadening of the absorption caused by enhanced electron–phonon coupling at elevated temperatures which increased scJ.Here, Δ is related to disorder resulting from the solution processed and phase separated polymer and fullerene regions, FigurePractically, it is important to understand the effect of temperature up to around 60 °C as this covers the temperature range encountered in most real‐world situations. Over the course of a single day, variations in temperature can significantly affect device efficiency and thus a temperature coefficient can be determined to minimize efficiency fluctuations induced by changing temperature.The ambient temperature also affects OPV lifetime. As described previously, OPV device degradation is accelerated by elevated temperature; a process reflected by Equation AF is the acceleration factor that occurs as a result of increased temperature and irradiance level, Ea is the activation energy of the degradation process and kB is Boltzmann constant with T1 (I1) and T2 (I2) being temperature (irradiance level) under testing conditions aE value over the temperature range is constant, 2) the rate of degradation depends linearly on irradiance, and 3) the spectral composition  of the radiation is unchanged at different irradiance levels.Here In recent years, the emergence of nonfullerene acceptor materials has increased the PCE of bulk heterojunction OPV devices.] Besides the high efficiency, another advantage of fullerene‐free OPV devices is excellent thermal stability. OPV devices using an unfused‐core based nonfullerene acceptor, DF‐PCIC, realized a PCE of 10.2%, and more importantly, after thermal treatment at 180 °C for over 12 h the devices retained ≈70% of their original efficiency.4.2Jsc and fill factor (FF) should be constant as a function of irradiance level as charge generation is proportional to the light intensity. Under open circuit condition, all photogenerated charge carriers recombine within the device. Thus, the recombination mechanisms can largely determine Voc of OPVs. As shown in FigureVoc varies logarithmically with illumination intensity, with its slope being equal to kT/e. From Equation Voc is particularly susceptible to the density of states (DOS) of the acceptor LUMO and donor HOMO. The DOS in the band tails is dependent on the illumination intensity as such states can be occupied by photoexcited electrons (in the acceptor) and holes (in the donor). At temperatures above zero, the quasi‐Fermi energies move into the gap thereby reducing the Voc. Based on the above discussion, the overall device efficiency will increase with increasing irradiance intensity; a process that is observed in silicon‐based solar cells. In an OPV however, charge carriers are generated through the processes of photon absorption, exciton diffusion, and separation followed by charge extraction. A higher irradiance level normally results in a higher exciton generation rate, although not all generated excitons undergo separation, as some fraction are lost through monomolecular or bimolecular recombination.Jsc on the irradiance level. At a high light intensity, more traps become populated, resulting in reduced recombination and superlinear increase of the photocurrent.−2. However the overall device efficiency decreases slightly with increased irradiance level due to the negative effect of decreased parallel resistance. Similar results were observed on OPV devices based on a squaraine dye,−2 to 6.2% at 3.5 mW cm−2 because of increased FF. It was believed that at a lower irradiance level, recombination was suppressed due to a lower charge carrier density in the device.The irradiance level both affects device metrics and also accelerates the device degradation rate. Ideally, the normalized A collection‐limited theory also confirmed the dependence of device efficiency on irradiance level, as shown in Figure −2, with a clear inflexion characteristic observed in the J–V curve. It was speculated that there was poor carrier transport through one of the layers or interfaces that prevented efficient charge‐extraction from the device. This study clearly illustrates the complexity of outdoor testing of OPV devices, with unexpected results sometimes emerging due to the combined effects of a number of environmental factors.It is worth noting that under outdoor conditions, higher irradiance levels usually correspond to higher temperatures, an issue that makes it difficult to distinguish between codependent factors. The effect of irradiance on device performance under outdoor conditions was investigated by Bristow et al.−2). Here the total absorption was recorded using UV–visible spectroscopy as a function of exposure time at different illumination levels. As shown in FigureData collection times in OPV lifetime tests can be shortened by exposing devices to concentrated illumination. In order to investigate the intrinsic degradation mechanisms of organic semiconductor materials (rather than complete devices), Tromholt et al.−2 for 30 min. This degradation was attributed to the desorption of oxygen from the zinc oxide electron transport layer during illumination. The study indicates therefore that sensitivity to other materials within the device is critical to engineer enhanced operational stability, and that performance at high irradiance level can reveal degradation mechanisms that are not observed under normal irradiance conditions. Indeed, under outdoor conditions, the irradiance level seldom reaches values as high as 150 mW cm−2, with the average irradiance level being much less than 1 sun. Degradation mechanisms that only occur at high irradiance level are therefore of secondary importance in outdoor lifetime tests.Although the active layer is the most sensitive part of an OPV device, the degradation of electron and hole transport layers, the device‐electrodes and interfaces also need to be considered. For example, Tromholt et al.4.3Moisture is a key degradation factor for OPVs. Glen et al.3 hole transport layer, with the results revealing that moisture induces significant degradation in devices containing a PEDOT:PSS layer. Devices that incorporated a MoO3 hole transport layer however appeared relatively stable even in atmosphere containing moisture  generally result in higher ambient temperatures which help to remove residual moisture from the PEDOT:PSS and the surrounding device by evaporation. In such circumstances, the hydroscopic nature of the PEDOT:PSS hole transport layer may be of secondary importance. Further work is needed to clarify such issues.Devices incorporating a PEDOT:PSS layer are believed to be more vulnerable to the effects of moisture because of its hygroscopic nature. Voroshazi et al.−6 g m−2 d−1 in OLEDs to achieve suitable lifetimes.−3 g m−2 d−1 was necessary to obtain a lifetime of several years. This less demanding WVTR requirement for OPVs points favorably to the use of low cost encapsulation solutions.Avoiding the ingress of moisture is essential to create stable OPV modules. It has been shown that the WVTR should be less than 10Interestingly, replacing fullerene acceptors by nonfullerene acceptor molecules can also increase the air storage stability. Using a nonfullerene acceptor, O‐IDTBR, P3HT based solar cells exhibited an efficiency of 6.4%, which is even higher than fullerene based P3HT solar cells. More importantly, the stability under ambient dark storage condition of O‐IDTBR:P3HT devices was determined to be superior to other fullerene based OPV devices.[[qv: 50a]] The first 60 h witnessed a fast degradation and then PCE remained relatively stable and retained 73% of the initial PCE after 1200 h ambient dark storage. This result confirmed the good stability of fullerene free OPV devices against water and oxygen in the ambient atmosphere.4.4Figure−1 over 200 cycles caused device efficiency to decrease from ≈2.0% to ≈1.5% after the first 5 cycles, with efficiency remaining constant afterward.Thermal fluctuations are a natural consequence of outdoor lifetime testing, with this process also contributing to the degradation of OPV devices. For this reason, thermal cycling tests form an essential component of tests applied to commercially available PV.5Figure Jsc and Voc in two ways. First, they increase the recombination rate, reduce the exciton lifetime and diffusion length and thus reduce steady state charge carrier density.Jsc. Secondly, charge carriers can fill sub‐band states near the quasi‐Fermi level. Even though this does not change the total charge carrier density,Voc loss.The OPV burn‐in process is related to device irradiation, as no obvious burn‐in is observed under dark storage.71BM blend films were deposited on a quartz substrate and exposed to 1 sun equivalent irradiance. PDS absorption spectra were then periodically measured and compared with an unexposed control film. As shown in FigureThe formation of sub‐band gap states has been confirmed using photothermal deflection spectroscopy (PDS).Jsc. By replacing PCBM with the nonfullerene acceptor rhodanine‐benzothiadiazole‐coupled indacenodithiophene (IDTBR),Photo‐induced dimerization of fullerenes is another possible origin of device burn‐in, as this reduces the active‐layer exciton‐harvesting efficiency and thus results in a loss in the short circuit current density. It has been shown that the external quantum efficiency (EQE) loss after exposure to illumination mainly corresponds to the reduced absorption of the fullerene.71BM based OPV devices observed that the nanostructure of the active layer and kinetics of free charge generation were apparently unchanged after burn‐in, and thus the initial degradation of device efficiency was attributed to generation of charge trapping states and suppressed charge carrier dissociation. Clearly, the morphological evolution of each BHJ system is highly dependent on the molecular structure of the particular materials used, with more work required to bring the different observations into a coherent framework.In PffBT4T‐2OD:PCBM based OPV devices,[[qv: 51b]] an abnormally strong burn‐in degradation has been observed, with the PCE dropping from 9.20% to 5.62% after dark storage for 5 days. Here, demixing of the donor/acceptor mixed‐phase within the BHJ film was attributed to be the cause of this considerable efficiency loss. Such spontaneous phase separation in mixed amorphous regimes can occur at room temperature and is independent of storage conditions. The authors claimed that this phenomenon is highly dependent on the material combination used in the BHJ film. This study indicates that not all OPV burn‐in losses are photo‐induced; rather morphological evolution is also a potential degradation mechanism in some specific material systems. In contrast, Pearson et al.Figure71BM acceptor. These results suggest better stability of fullerene free OPV devices over those using fullerene acceptors. However, the light soaking experiments lasted for only 60 h, which makes it impossible to extract the Ts80 lifetime of the fullerene free OPV devices and so a direct comparison of the published data cannot be made.Interestingly burn‐in losses are nearly negligible if the fullerene acceptor in PffBT4T‐2OD based OPV devices is replaced with a nonfullerene derivative.6We have reviewed the status of outdoor lifetime studies of OPVs. The reported outdoor operational lifetime of certain OPV modules has now reached a period of several years; a promising result considering that 10 years ago, typical device lifetimes were in the range of a few days to weeks.OPV lifetime studies conducted under laboratory conditions were briefly reviewed. The “o‐diagram” methodology and accumulated energy dose analysis can be used to make comparisons between indoor and outdoor lifetime studies, however indoor‐based tests do not fully simulate the outdoor environment. Direct measurements of OPV outdoor lifetime were reviewed. Here we discussed the development of experimental systems used in outdoor lifetime studies, with recommendations made to increase the consistency of different outdoor lifetime tests. Long‐term outdoor lifetime test results for different OPV material‐systems were then summarized. It was highlighted that certain OPV modules fabricated using roll‐to‐roll processes and encapsulated using flexible PET foils have very promising operational stability when measured under outdoor conditions. In the majority of studies however, OPVs are fabricated using nonscalable techniques and have a limited active area. Nevertheless, such studies are useful in exploring the intrinsic stability of OPV materials and devices when exposed to different geographic locations and climatic conditions. In outdoor lifetime conditions, the irradiance level, temperature, humidity, and thermal fluctuation have been identified as key degradation factors, with their influence on OPV performance and stability discussed. Finally, the burn‐in phenomena observed during the initial period of OPV operation is introduced, with burn‐in free OPVs based on nonfullerene acceptors being highlighted. The stability of fullerene free OPV devices looks promising based on current research results, especially under thermal stress and light soaking. However, more systematic investigation is needed and outdoor lifetime studies of devices with nonfullerene acceptors are needed.70BM), and thus it will be interesting to extend it to new donor/acceptor blends having high efficiency—even if such tests are initially performed over a limited period under the ISOS‐O‐1 basic testing protocol.Although considerable progress has been made in outdoor lifetime testing of OPVs, there are still some challenges that remain including the development of a standard outdoor lifetime testing platform and testing strategy. In addition, a comprehensive, predictive method to fully link lifetime tests conducted under indoor (accelerated) conditions to outdoor real‐world conditions should be developed. In general, outdoor lifetime testing is generally limited to the most well‐established material systems (such as P3HT:PCBM and PCDTBT:PCThe authors declare no conflict of interest.


Genetic data have great potential for improving fisheries management by identifying the fundamental management units—that is, the biological populations—and their mixing. However, so far, the number of practical cases of marine fisheries management using genetics has been limited. Here, we used Atlantic cod in the Baltic Sea to demonstrate the applicability of genetics to a complex management scenario involving mixing of two genetically divergent populations. Specifically, we addressed several assumptions used in the current assessment of the two populations. Through analysis of 483 single nucleotide polymorphisms (SNPs) distributed across the Atlantic cod genome, we confirmed that a model of mechanical mixing, rather than hybridization and introgression, best explained the pattern of genetic differentiation. Thus, the fishery is best monitored as a mixed‐stock fishery. Next, we developed a targeted panel of 39 SNPs with high statistical power for identifying population of origin and analyzed more than 2,000 tissue samples collected between 2011 and 2015 as well as 260 otoliths collected in 2003/2004. These data provided high spatial resolution and allowed us to investigate geographical trends in mixing, to compare patterns for different life stages and to investigate temporal trends in mixing. We found similar geographical trends for the two time points represented by tissue and otolith samples and that a recently implemented geographical management separation of the two populations provided a relatively close match to their distributions. In contrast to the current assumption, we found that patterns of mixing differed between juveniles and adults, a signal likely linked to the different reproductive dynamics of the two populations. Collectively, our data confirm that genetics is an operational tool for complex fisheries management applications. We recommend focussing on developing population assessment models and fisheries management frameworks to capitalize fully on the additional information offered by genetically assisted fisheries monitoring. It has received considerable interest from studies focusing on basic as well as applied research in both aquaculture and wild populations, and the separation of coastal and offshore populations in the Northern Atlantic  of the two populations. Subsequently, we use the reduced, so‐called high‐graded, panel of markers to study population mixing and dynamics with high spatial and temporal resolution in a large number of individuals collected within the mixing zone. We use these data to investigate if current management assumptions are accurately describing the dynamics of mixing in the region, that is, addressing the assumptions related to geographical patterns of mixing for juvenile and adults. Finally, we use the genetic data in combination with environmental data to assess possible mechanisms driving population mixing.22.1The geographical focus of this study was at the Arkona Basin region in the Baltic Sea Figure  where pr2.2FST . In addition, markers on different linkage groups were also only selected if they showed low levels of linkage disequilibrium (max r2 < 0.25) to ensure that all markers would provide independent information. This procedure also limited biases for population assignment from including linked markers in the well‐described highly differentiated genomic regions  to examine geographical patterns of mixing for juveniles and adults and the relationships between mixing proportions and potential environmental drivers of mixing. Specifically, we modelled the distribution of mixing proportions while accounting for spatial correlation induced by the sampling design using the following base model extended to include geographical and/or age‐class (juvenile vs. adult) covariates according to Table ip, out of ipN fish from sampling event  i at sampling period (defined as year‐quarter combinations) p is assumed to follow a binomial distribution with probability πip. Expected values and variance of Eastip are defined by E(Eastip) and var(Eastip). Salinity, oxygen content, and water temperature in the Arkona Basin at the time and location of catch were extracted from the hydrodynamic Kiel Baltic Sea Ice‐Ocean Model )/SD(x) prior to modelling.In these models, number of eastern fish, Eastip is from the area west or east of 13° E, whereas M2 includes factor “Juvenile”, describing whether observation ip pertains to juvenile or adult fish. Due to sparse number of samples containing adults from the western area, the interaction between Area and Juvenile could not be tested. In M3, a second‐order random walk model “F(utmXip)” was included to capture an overall  east–west trend on ipπ as the study area extension was primarily in the east–west direction. This was extended further in M4 by allowing the second‐order random walk to vary between juveniles and adults. Models were compared using the Watanabe–Akaike information criteria  and the associated covariance matrices are modelled using Matérn correlation function and numerically approximated using SPDE . A logit link function was used to model ipπ as a function of the linear predictor function. The model was fitted in a Bayesian framework using R  but never both. Simulated F1 hybrids had intermediate admixture coefficients and 95% CIs which never included 0 or 1 Figure b,c. The 3.3Assignment of cod collected between 2011 and 2015 showed mechanical mixing of eastern and western cod in the study region Figure . Analyse3.42, salinity, and temperature) as the 95% credible intervals for parameter estimates included 0  and using a gradual geographical transition in mixing proportions M4; Table ; Table 44Sustainable fisheries management relies critically on our ability to identify biological populations, and to incorporate information about their spatial distributions and mixing into management , the results also indicated that the major geographical break in mixing proportions may be different for juveniles and adults, at least for the data included in this study. Consequently, the result indicates that the current approach assuming similar proportions for juveniles and adults does not accurately account for the dynamics of mixing, and that proportions should therefore be estimated for both life stages separately to fully track the dynamics of mixing in the region.The geographical distributions and size distributions of small juveniles from the two populations provide interesting information about the underlying dynamics potentially driving juvenile mixing proportions, and they indicate important effects of differences in reproductive biology and growth in the two populations Hüssy, . The conEarlier work has used simulations to evaluate possible consequences of disregarding independent population dynamics of identified genetic units within a management area (Goethel & Berger, 5We have shown here that knowledge of population origin can provide an increased understanding of complex dynamics in a marine fishery on mixed populations. We evaluated the validity of current assumptions used in stock assessment of mixing Baltic cod stocks. Our analyses contribute to refining future assessment and management procedures; in particular, in relation to differentiating mixing patterns for juveniles and adults and to examining temporal patterns of mixing with relatively high geographical resolution. Here, genetics provide a fast and operational tool applicable to all life stages and even historical samples (Bonanomi et al., Several marine fish species show similar complex patterns of population interaction as the Baltic cod examined in this study (Bekkevold et al., None declared.https://doi.org/10.5061/dryad.83765smData available from the Dryad Digital Repository:  Click here for additional data file. Click here for additional data file. Click here for additional data file. Click here for additional data file. Click here for additional data file. Click here for additional data file.


Short rotation plantations are often considered as holding vast potentials for future global bioenergy supply. In contrast to raising biomass harvests in forests, purpose‐grown biomass does not interfere with forest carbon (C) stocks. Provided that agricultural land can be diverted from food and feed production without impairing food security, energy plantations on current agricultural land appear as a beneficial option in terms of renewable, climate‐friendly energy supply. However, instead of supporting energy plantations, land could also be devoted to natural succession. It then acts as a long‐term C sink which also results in C benefits. We here compare the sink strength of natural succession on arable land with the C saving effects of bioenergy from plantations. Using geographically explicit data on global cropland distribution among climate and ecological zones, regionally specific C accumulation rates are calculated with IPCC default methods and values. C savings from bioenergy are given for a range of displacement factors (DFs), acknowledging the varying efficiency of bioenergy routes and technologies in fossil fuel displacement. A uniform spatial pattern is assumed for succession and bioenergy plantations, and the considered timeframes range from 20 to 100 years. For many parameter settings—in particular, longer timeframes and high DFs—bioenergy yields higher cumulative C savings than natural succession. Still, if woody biomass displaces liquid transport fuels or natural gas‐based electricity generation, natural succession is competitive or even superior for timeframes of 20–50 years. This finding has strong implications with climate and environmental policies: Freeing land for natural succession is a worthwhile low‐cost natural climate solution that has many co‐benefits for biodiversity and other ecosystem services. A considerable risk, however, is C stock losses  due to disturbances or land conversion at a later time. How can spare cropland be used more efficiently in terms of climate change mitigation? By growing short rotation coppice for bioenergy or allowing cropland to revert to its natural state. We show that the more beneficial option depends on the timeframe considered, biophysical conditions in the considered region, upstream emissions of fuel supply, and the efficiency of the particular bioenergy route in displacing fossil fuels. AlthougAn option for providing possibly large quantities of biomass without interfering with forest C stocks are purpose‐grown biomass plantations managed in short rotation . If established on current agricultural land, such plantations usually result in the buildup of C stocks in biota and soils rather than their reduction , thereby acting as a potentially significant long‐term C sink. The world's croplands are mostly located in ecological zones that would revert to forests if left undisturbed, but there are also cropland areas located in regions characterized as shrublands, desert, or steppe (see Table Contributions of bioenergy based on SRC (SRC‐based bioenergy) and natural succession to the reduction in atmospheric C are here referred to as “carbon benefits” (C benefits). This definition of C benefits differs from the C benefit index recently proposed by Searchinger, Wirsenius, Beringer, and Dumas , which rDepending on site‐specific conditions , the considered timeframe, and the efficiency of the respective bioenergy pathways, natural succession might represent a worthwhile alternative to fossil fuel substitution with biomass from energy plantations. Erb et al.  have recThese studies illustrate that it depends on various factors whether natural succession (nSucc) or SRC‐based bioenergy (BE) provides higher cumulative C benefits per unit area. A systematic comparison of the respective C benefits has so far not been worked out.The aim of this study is to fill this gap by investigating the subject on a global scale, taking into account regionally diverse influencing parameters. We systematically analyze the effect of largely arbitrary methodological decisions .More specifically, this study aims at answering the following research questions: How do nSucc and BE compare in terms of cumulative C benefits, with regard to the predominating biophysical conditions in different world regions? To what extend does the superior option depend on the considered bioenergy pathway, and the assumptions on the fossil fuel and conversion route it displaces? What are the main influencing factors determining the superior option, and what do the findings imply for global climate mitigation strategies and policies?C benefits denote total cumulative carbon savings resulting from either option per unit area over a defined period of time. C benefits from nSucc and BE are always compared for the same area and spatial distribution of land. Potential differences in albedo effects of natural vegetation and SRC are not considered. Moreover, we do not consider economic aspects of the two C mitigation options, implications for landowners or policy measures for incentivizing SRC or natural succession on agricultural land. Such issues are beyond the scope of this biophysical assessment of C benefits and must be addressed in subsequent research.In this study, we only consider short rotation plantations  that are typically harvested in periods of 2–5 years. Conventional energy crops  as well as perennial grasses  are not within the scope of this work. We calculate C stock changes in accordance with IPCC methods and largely based on IPCC default data IPCC, . This apWe further check the robustness of our results with sensitivity analyses regarding uncertain parameter values and by considering nonlinear growth functions  correspond to the total difference in C stocks between the initial and the final year of the considered timeframe:The following figure illustrates the fundamentals of the research topic and the methodological approach: The left panel of Figure In contrast, the development of C stocks in SRC , using a high‐efficiency bioenergy technology, more fossil C is displaced per unit of biogenic C . Hence, assuming gradual LUC is not only more realistic than immediate LUC but also has the advantage that it leads to continuous C benefit curves instead of “sawtooth profiles.” It therefore constitutes a default assumption in our modeling approach. The default transition period is 10 years, and an alternative duration of 20 years is assumed in a sensitivity analysis.BE) result from C stock changes and displacement of fossil fuels (CBfuel_disp):In the case of BE, C benefits , Lsupply_chain is relative biomass loss along the biomass supply chain, TF is the considered timeframe, and TP is the assumed transition period of LUC.CBApart from a global perspective, we differentiate between 11 world regions  and for deserts 2 tdry/ha  among world regions , and agricultural practices . Under Tier 1 approaches  and a reference fossil fuel (CEfossil), and the conversion efficiencies η of the considered bioenergy pathways (index “BE”) and the respective fossil‐based counterpart (index “fossil”):DF is defined as the ratio of fossil carbon emissions to biomass carbon emission for an equal amount of  energy supplied. Following Marland and Schlamadinger , we calcDepending on the bioenergy pathway, efficiencies represent thermal or electrical plant efficiencies or feedstock‐to‐fuel conversion efficiencies (of second‐generation biofuel production processes or petroleum refineries). Hence, DFs reflect (a) energy losses during the respective conversion from primary resource to final energy and (b) the different emission factors of biomass and fossil fuels.In the case of combined heat and power (CHP) generation, we consider electricity as primary output and apply established allocation methods to determine the share of electricity‐related emissions. To consider upstream emissions of fuel supply , we apply the following extended equation:BM and UEfossil denote upstream emissions per energy unit of biomass and fossil fuel, respectively. Combustion emission factors are taken from IPCC Guidelines  is referred to as “relative C benefits from nSucc.” Second, we present sensitivity analyses for uncertainties related to SRC, assuming transition periods of 10 (default) as well as 20 years. Third, we compare C benefits of nSucc and BE in absolute numbers for 11 world regions and elaborate on similarities and differences between the regions as well as the global weighted average. And fourth, we consider dynamic DFs and present scenarios for the timeframe 2020 to 2100. In the latter two cases, we take into account linear (default) as well as nonlinear growth functions for nSucc.The results are presented in the following ways: First, we compare the relative performance of nSucc in relation to BE, with DF being varied from 0.1 to 1. The ratio , C benefits from nSucc generally exceed those from BE, regardless of the timeframe, and at 0.3, it takes more than 70 years for BE to achieve higher cumulative C savings. In contrast, DF values at least slightly higher than 0.4 result in BE being superior to nSucc for all considered timeframes. Still, it is remarkable that even at high DF , the carbon savings from nSucc are in the range of about 50%–75% of the savings from BE for timeframes up to 50 years.The reason why relative C benefits from nSucc are surprisingly low for 20‐ and 30‐year timeframes and low DF is higher initial biomass growth in SRC than in nSucc. For low DF values and short timeframes, the C benefits from BE are largely due to C stock increase in SRC, whereas for medium to long timeframes , C benefits from BE mostly originate from fossil fuel displacement.Figure The figure also illustrates the potentially large impact of supply chain emissions. “Unfavorable” bioenergy scenarios, characterized by long‐distance supply chains for biomass displacing efficient fossil fuel supply, exhibit DF ranges that are significantly lower than under exclusion of upstream emissions. The impact of high supply chain emissions is especially pronounced in case of biomass conversion routes with low efficiencies, such as second‐generation biofuel production or electricity generation without heat utilization. The overall range for unfavorable bioenergy scenarios is 0.1–0.68.In contrast, if biomass is produced locally and displaces fossil fuels that are extracted with high energy input , the DF range for heat and electricity generation is 0.42–0.9. The DF of 2G biofuel production remains low at 0.22–0.37 for pessimistic projections and increases to up to 0.5 for the most optimistic projections.3.24 runs. Random variables are NPPpot  and on‐site aboveground biomass losses Lon‐site (uniform distribution from 10% to 30% of NPPpot). Supply chain losses are kept constant at 10% of harvested biomass. The aggregate effect of the assumed ranges is that the highest possible value for energy plantation yields in each region is almost twice as high as the lowest possible value  and a pessimistic scenario (“LOW”) regarding fossil fuel displacement from 2020 to 2100. Building upon the ranges shown in Figure Figure 4Recent studies have argued that protection and enhancement of natural carbon sinks should seriously be considered as alternative to bioenergy  constant level after a period of time that ranges from few decades to over one century according to IPCC default values. In case of SRC, fossil fuel displacement must compensate for periodical depletion of aboveground biomass C stocks. However, the amount of (fossil‐based) C emissions displaced per unit of biogenic C used for energy is normally smaller than 1 due to usually lower conversion efficiencies and a relatively high emission factor of wood. If biomass displaces natural gas  or oil derivatives via 2G biofuels, the DF is even smaller than 0.5. The lower the DF, the slower the process of compensating for C stock depletion in energy plantations.The fact that C stocks in energy plantations are restored within relatively short periods after harvesting might foster the perception of “carbon neutrality,” and that net C savings are always achieved on short term, regardless of the efficiency of bioenergy use. This misperception stems from neglecting the counterfactual scenario, that is, C sequestration in natural vegetation; in fact, high efficiency in displacing fossil C—that is, high DFs—is of crucial importance.2No default values on deadwood are provided in IPCC  because  Substituting linear growth functions for nonlinear ones did not significantly alter the results. Still, future research should be dedicated to this aspect, not only to have nSucc represented with realistic growth functions but also due to strong evidence that biomass C stocks in old‐growth forests are actually underestimated in current IPCC default data  until the mid‐21st century at comparatively low costs (see Griscom et al.,  Click here for additional data file.


VBM) studies on spinocerebellar ataxia type 2 (SCA2).To identify the consistent findings from the whole‐brain voxel‐based morphometry  were systematically searched in PubMed, Embase databases from January 2000 to June 2017. The coordinates with significant differences in gray matter (GM) and white matter (WM) between SCA2 patients and HCs were extracted separately from each cluster. A meta‐analysis was performed using anisotropic effect size‐based signed differential mapping (AES‐SDM) software.The whole‐brain SCA2 patients and 124 HCs were included in the GM meta‐analysis. Four of the five studies with 50 SCA2 patients and 109 HCs were included in the WM meta‐analysis. Significant and consistent GM volume reductions were detected in bilateral cerebellar hemispheres, cerebellar vermis, the right fusiform gyrus, the right parahippocampal gyrus, and the right lingual gyrus. The WM volume reductions were observed in bilateral cerebellar hemispheres, cerebellar vermis, middle cerebellar peduncles, pons, and bilateral cortico‐spinal projections. The findings of the study remained largely unchanged in jackknife sensitivity analysis.A total of five studies with 65 GM volume reductions in SCA2 patients were not limited in cerebellum while significant WM volume reductions widely existed in cerebellum and pyramidal system. The findings provide morphological basis for further studies on SCA2.The consistent findings from our meta‐analysis showed that  Due to the genetic heterogeneity, patients with SCAs can develop impaired vision, dysarthria, pyramidal signs, ophthalmoplegia, extrapyramidal signs, loss of sensory function, dementia, or any combination of these abnormalities  is a quantitative voxel‐based meta‐analytic tool for neuroimaging studies that has been widely used in various neurodegenerative diseases  and (“voxel‐based” OR “VBM” OR “morphometry”). An additional search was also conducted in the reference list of relevant articles.Studies were considered for inclusion if they (a) reported the whole‐brain VBM results of GM volume or WM volume from a comparison between SCA2 patients and HCs; (b) reported the whole‐brain results of changes in a standard stereotactic space with three‐dimensional coordinates ; (c) used significance thresholds corrected for multiple comparisons or those uncorrected with spatial extent thresholds; and (d) were peer‐reviewed and published in English. For those studies that met the aforementioned inclusion criteria with overlapping samples, only the study with the largest sample size was included to avoid repetitive data. Studies were excluded if (a) there was no HC group; (b) stereotactic coordinates of the reported changes in the whole brain were not obtained even if we corresponded to authors by email; and (c) the data overlapped with those of another article.2.2t statistics, z scores or p values) with significant differences between patients and HCs in GM and WM volume were extracted by two neurologists  independently according to the AES‐SDM software tutorial. If there were disagreements, the third neurologist (Huifang Shang) would check the data and make a decision finally.In each study, coordinates and their effect sizes (2.3http://www.sdmproject.com) to compare the differences of GM and WM volume between SCA2 patients and HCs. In brief, we first converted all the other effect size  into t statistics and then entered the data obtained into the SDM software. The GM volume analysis and WM volume analysis were performed separately and used different masks. Standard MNI maps were then created, and the mean map was calculated representing the weighted mean regional differences in GM and WM volumes. The default kernel size and statistical thresholds  were used to balance the false positive and negative. A systematic whole‐brain voxel‐based jackknife sensitivity analysis was conducted to test the replicability of the results.The meta‐analysis of included studies was performed in a standard process using the SDM software package . The reductions in WM volume are detected in cerebellar medulla, cerebellar afferent fibers (middle cerebellar peduncles), and pyramidal system. The high replicability after jackknife sensitivity analysis confirmed the robustness of the findings.4.1Atrophy of cerebellum was almost reported in all SCA2 imaging studies and corresponded well to the pathological changes and clinical features, but these studies reported various and inconsistent subregions of atrophy. In the present study, consistent reduced volumes of GM and WM are identified in cerebellar hemispheric lobule III‐VIII and Crus I/II. A previous activation likelihood estimate meta‐analysis confirmed that lobule IV/V and VIII of cerebellum dominate sensorimotor control other than higher‐level functions such as language, spatial, and executive functions  identified in the current study contains cerebellar vermal lobules VI/VII which have been reported to participate in control of eye movements (Jenkinson & Miall, It should be pointed out that we found larger reduced volumes in the right cerebellar hemisphere than those in the left. Such asymmetry was difficult to explain as most of included studies reported symmetric atrophy between the two cerebellar hemispheres. Perhaps, the coordinates of the regional volume reductions in the left cerebellar hemisphere showed the between‐study heterogeneity, which would influence the result of the SDM approach. Future studies with larger sample sizes may help to verify the asymmetry.4.2A meaningful result of our study is the GM atrophy in the parahippocampal gyrus, reported once in VBM study of SCA2 (Mercadillo et al., The GM atrophy of fusiform gyrus is one of the other important findings in the current study. Fusiform gyrus and the parahippocampal gyrus were reported participating in ventral visual pathway (Op, Beeck, Haushofer, & Kanwisher, The lingual gyrus has been reported to be involved in the visual recognition and episodic memory (Kukolja, Goreci, Onur, Riedl, & Fink, In an interesting manner, all these volume reductions of supratentorial areas are located in the right side may implicate the interaction between these supratentorial areas and cerebellum through the ipsilateral networks as predominate right side of cerebellum atrophy was identified in our study and most of these supratentorial regions have been reported to be functional connectivity with different cerebellar subregions (Stoodley & Schmahmann, It should be noted that our results did not show significant atrophy of WM in these supratentorial areas, which does not indicate the WM of these region remains normal in SCA2 patients as mild‐to‐moderate damage of WM may not manifest volume reductions. In reality, higher MD in WM of the parahippocampal area was reported (Hernandez‐Castillo et al., 4.3The middle cerebellar peduncles are the main afferent pathway to the cerebellum, composed by WM fibers originated from the contralateral pontine nuclei (Morales & Tomsick, 4.4Several limitations should be acknowledged in our study. First of all, studies from which we could not extract data and in languages other than English were not included. The heterogeneous and relatively small sample size of included studies might not reflect a standard SCA2 population. Second, the heterogeneity of different methods in VBM studies, including preprocessing protocols, smoothing kernels, and statistical thresholding methods, cannot be ruled out entirely. Third, due to the incomplete information and heterogeneity of included studies, we did not make meta‐regression analysis to explore potential correlations between the GM and WM regional volumes and clinical features such as age, CAG repeats, motor impairments, or cognitive functions. More studies on SCA2 with detailed clinical data in the future will improve the reliability of the meta‐analysis. At last, all of the included studies were cross‐sectional studies that only reflected static alterations of GM and WM volume in SCA2 patients. In reality, a previous longitudinal study using tensor‐based morphometry reported that from baseline to follow‐up, SCA2 patients showed a progressive atrophy of GM and WM in the midbrain and cerebellum, but no volume loss in the supratentorial compartment compared to HCs (Mascalchi et al., 5The consistent findings from the present meta‐analysis showed that GM volume reductions in SCA2 patients were mainly focused on cerebellum and a part of cortex in supratentorial regions related to several networks regulating cognitive functions and emotions. The significant WM volume reductions widely existed in cerebellum along with its afferent pathways and pyramidal system. These findings provide morphological basis for further studies in SCA2.