The hourglass is one of the apparatuses familiar to everyone, but reveals intriguing behaviors peculiar to granular materials, and many issues are remained to be explored. In this study, we examined the dynamics of falling sand in a special form of hourglass, i.e., a wedge-shaped hopper, when a suspended granular layer is stabilized to a certain degree. As a result, we found remarkably different dynamic regimes of bubbling and cavity. In the bubbling regime, bubbles of nearly equal size are created in the sand at a regular time interval. In the cavity regime, a cavity grows as sand beads fall before a sudden collapse of the cavity. Bubbling found here is quite visible to a level never discussed in the physics literature and the cavity regime is a novel phase, which is neither continuous, intermittent nor completely blocked phase. We elucidate the physical conditions necessary for the bubbling and cavity regimes and develop simple theories for the regimes to successfully explain the observed phenomena by considering the stability of a suspended granular layer and clogging of granular flow at the outlet of the hopper. The bubbling and cavity regimes could be useful for mixing a fluid with granular materials. Dynamics of dense granular materials is one of the challenging problems in physics1345681012131420Here, we studied granular flow in an hourglass without circular symmetry  when a suspended granular layer could be stabilized to a certain extent, with the aid of cohesion force between sand grains, friction with side walls, and low permeability of the sand layer (which leads to the pressure difference developed in the layer)81020The cavity regime cannot be categorized into any previously known phases: it is neither continuous, intermittent nor completely blocked phases. Any systematic physical study on this original regime using a small-scale laboratory setup have never been discussed in the physics literature. We show that this intriguing phenomenon can be understood by the balance between the gravitational and frictional forces.The bubbling reported here is quite visible to a level never reported in the literature. Although a similar phenomenon is reported8Since the bubbling in the present study is so clear as if it appeared in liquid, it is possible to study the bubble size and the rising speed in detail. As a result, we elucidate the dependence of the period of bubble nucleation on the geometry of hourglass and clarify the importance of clogging in the periodic motion.Note that, although visible bubbling in a granular layer has been discussed for fluidized beds24H, thickness L, and slope α (that defines the angle θ via α = tan θ), as shown in w of the cell is much larger than the average diameter d of the beads. By rotating the cell upside down, all the glass beads in the cell that are initially located above the outlet start falling down through the outlet due to gravity.We use a transparent closed cell of height 2d, L, θ, and w, the dynamics are categorized into three regimes. (1) Bubbling regime: small air bubbles are regularly created at the outlet and goes up to disappear, as shown in 2). (3) Intermediate regime: a cavity grows upwards first but later glass beads accumulate near the clogged outlet, leading to a “rising cavity,” as in Depending on the parameter set, The dynamic regime is determined as a result of competition of the stability of the bottom free surface of the sand layer and the clogging at the orifice. A cavity can keep growing only when the free surface is stable and only when clogging is difficult to occur. Bubbling occurs under the opposite conditions (low stability and easy clogging): a bubble looks as if to “rise up” in the granular medium, as a result of the collapse of the top part (due to low stability) followed by the accumulation of sand (due to clogging).kγd to the gravitational force ρgd3 for a particle of diameter d, which scales as k(l/d)2, becomes larger when particle becomes small. Here, γ, ρ and g are the surface tension of water, the density of the particle, and the gravitational acceleration, defining the capillary length k, which reflects the amount of water at the contacts of particles, would be very small. However, for example, when d is 30 μm, the ratio k(l/d)2 could become comparable to unity because l is about 3 mm: for small particles, the cohesive force can excel the gravitational force. Another reason for the high stability of fine particles is the small permeability of the sand layer formed by fine grains. This will help create pressure difference in the sand layer, contributing the stability. This point will be discussed in more detail in the next two sections.The stability is increased when particles are fine. This is because the cohesive force between particles becomes large when the sand is fine. This is well-known at least empirically and explained frequently in terms of capillary bridges between sand particles originating from a tiny amount of water located at the contacts between grains1L) is understandable from snapshots in The clogging occurs easily when the slope is small and when the cell is thin. Easy clogging for small slopes is reasonable: the smaller the slope is, the more concentrated towards the outlet the falling sand beads are. Easy clogging for thin cells , the cell thickness L is large, and the angle θ is large (for clogging to be difficult), whereas the bubbling regime tends to be seen under the opposite conditions, i.e., when d is large, L is small, and θ is small. These tendencies are clearly confirmed in w = 1 mm.On the basis of the above points (1)–(3), the phase diagrams in nth bubble is created as follows. First, a cavity is nucleated at the outlet at time nth cavity). At time nth bubble). The nth bubble thus created rises up in the granular medium upwards, whereas after a short waiting time n + 1)th cavity is nucleated at the clogged part at the bottom, which leads to the next bubble.In the bubbling regime, the ht and hb ( is comparable to the rising speed of the nth bubble defined after Bn)( = (dhb/dt)n) of the suspended granular layer, which can be determined as follows. By introducing a life time τ of a sand particle after the moment the sand particle is exposed to the sand-air interface (positioned at height z = hb), we simply obtain the growing speed of a cavity or the rising speed of a bubble,The dhb/dt)n). This means that the life time τ and the rising speed of bubbles are also independent of n and hb . The physical nature of τ will be explored in Discussion.As seen in n - independence of the initial bubble size Bn) and thus given by S = Lhb/α . The maximum flux at the outlet Q0 is estimated as Q0 = ϕcS0V0, with the section area S0 = 2wL of the cell at the outlet (z = 0)  for sand beads falling off from the surface after gliding on the cell wall of the slope α. By noting that Qb < Q0 . From this clogging condition and The = 0) see  and the B, that is, why n. Since the waiting time n-independent, the n-independence of V and B justify the n-independence of Tn)( [see where T(n) see .B is predicted as an increasing function of αw/d from B ≃ 2β obtained in the limit Δ ≪ β. Then all the following behaviors shown in τ on d is relatively weak. (1) V and B are independent of L. (2) V is independent of w and that B increases with w. (3) V increases with d and that B decreases with d. (4) V is independent of α and that B increases with α.The agreement of the above theory with experiment is seen in different ways in hb till the bubble disappears. This active phase is followed by the inactive phase in which the flow through the orifice is stopped and the pressure difference decreases till the creation of the next cavity. During the active phase, because of the transfer of sand from the upper to lower chamber, the pressure in the sand layer near the orifice becomes larger than the pressure in the upper chamber due to the compression and expansion of air in the lower and upper chambers, respectively, provided that the chambers are closed  was too large to pass through the orifice rapidly.” Note here the following points for this series of study8Ti + Ta was quite robust and independent of the grain size and explained the characteristic order of the period by the Darcy dynamics in the first series of studyThe importance of a weak and localized pressure difference created near the orifice was clearly shown in the intermittent regime8ht. In addition, more than one bubble can coexist in the sand layer in the present case.Bubbling in the present study and in the previous studies8Ti in the previous study, in which the pressure difference is reduced, corresponds to the waiting time tw in the present study. Our theoretical arguments based on the clogging condition given above provides an estimate for the counterpart of Ta in which period the pressure difference is increased, whereas any explicit estimates are not available in the previous studies8Ta is here defined as ta increases with α and w and decreases with d ))Ti in thta on d in the present study is the opposite to that of Ta on d: ta decreases with d whereas Ta increases with d. This is a clear experimental fact while the dependence of ta on d is explained by the present theory. This suggests that although the physical mechanisms of bubbling in the present and previous studies are conceptually similar but the details are quite different.Note that the dependence of ht as a function of hb at the moment of collapse; the critical values are respectively denoted In Fg acting on the sand layer exceeds friction force Ffric acting on the layer from the cell walls. The force Fg is simply estimated by ρ representing the density of the granular layer. The force Ffric is estimated as L ≫ H as shown in Methods. When a cavity starts growing, the condition L ≫ H givesThis linear relation withL = 56 mm, which satisfies the necessary condition L ≫ H for m as a function of α, as shown in m is linearly dependent on α, from which the friction coefficient is obtained as This equation explains the linear relation shown in hb is increasing, the height ht is almost fixed to the initial position, as illustrated in ht is completely fixed and the sand layer is completely impermeable, the pressure difference should not be created at all. This is because, in such a case, as illustrated in H > z > ht), and no volume change occurs also for the air in the space below the sand layer and above the sand accumulated at the bottom of the lower chamber , obviously helps stabilize the sand layer because of the viscous drag due to air, especially because the permeability becomes smaller when the grain size is small. However, the fact that the pressure gradient seems almost completely relaxed by the time of the collapse , as discussed in (b), implies that the collapse condition cannot be strongly affected by the pressure gradient.Even if a small pressure difference is created as suggested in (1), the pressure difference seems to be considerably reduced in reality during the formation of the cavity. This is experimentally supported in two ways. (a) Careful observation near the top surface of the sand layer  and the numerical coefficient c is also very small as suggested in (2). Here, P is the initial pressure of the chambers and A is a characteristic area of the layer, whereas V and ΔV are a characteristic volume of chambers and changes in them, respectively. Since ΔV/V and A roughly scale as δ/H and LH, respectively, the ratio of the pressure force to the gravitational or frictional force scales as δ is the downwards shift of ht during the cavity formation, which produces the pressure gradient. As mentioned in (1), δ is significantly small in the cavity regime. Thus, the ratio c is very small due to the effect of relaxation described in (2).The collapse condition governed by the gravitational and friction force can be dimensionally justified. The two forces acting on the suspended granular layer are given both as The two independent checks for the agreement between theory and experiment shown in The effect of pressure gradient discussed for an intermittent regime in the previous studies8τ, although a better physical understanding of the life time τ possibly related to a reorganization time of granular structure will be an important issue to be resolved in the future. One possibility is based on the free fall motion of a grain: this gives η and with the characteristic velocity U scaling as d/τ, we obtain τ ~ ms. This is comparable to τ estimated by V and d on the basis of V and B in Fig. 3 (d).At this point, we discuss crude estimates for τ as indicated above, the precise control of humidity is experimentally difficult. For example, the data in V, B, and T in While humidity affects However, we expect the humidity dependence is not too strong. This is because of the following reasons: (1) The bubbling regime appears for larger grains so that the effect of cohesion should be relatively weak in the bubbling regime; (2) The qualitative agreement between theory and experiment in the bubbling regime was obtained, in spite of the non-precise control of humidity.The reason we observed bubbling and cavity collapse in a hopper that are quite visible to a level never reported in the literature may be the following. The key factor that we successfully observed spontaneous bubbling and cavity collapse in a hopper is the stabilization of a suspended granular layer. When the bubbling regime is observed, the cell thickness is relatively small and the cell is quasi-two dimensional. This helps stabilize a suspended layer because the layer is sandwiched in a small gap between the cell walls, to create a cavity at the outlet, which is soon closed by clogging. When the cavity collapse is observed, the cell thickness is relatively large. In this case, the cohesion force between small sand particles helps stabilize a suspended layer, to create a cavity at the outlet, which is not soon closed because clogging is harder to occur when the cell thickness is large. These stabilization conditions have not been well satisfied in most of the previous physical studies.However, a phenomenon similar to the one in our bubbling regime are reported88The spontaneous bubbling and cavity collapse we discussed in this study may be useful for mixing a fluid and powder in industrial applications. This is expected because forced fluidization processes are essential for applications, such as petroleum refining and biomass gasification, in which bubbles created in fluidized bed reactors affect the efficiency26To conclude, the present results reveal novel aspects of granular dynamics when a suspended granular layer becomes stabilized to a certain extent and the interplay of the stabilized granular bed and clogging of the granular flow is important, which could open new avenues of research within granular physics. We have shown (1) that bubbling and cavity emerge as a result of the interplay of the clogging and the stability, (2) that the rising speed of a bubble (comparable to the growing speed of a cavity), the initial bubble size, and the constant formation of bubbles are understood by introducing a life time for a sand particle exposed to the interface of a suspended granular layer and a clogging condition resulting from the competition between two characteristic flow rates, and (3) that the sudden collapse of the suspended layer is explained by considering a force balance between gravity and solid-like friction with walls. The present results would be relevant to applications for mixing a fluid with grains.H is fixed to 162 mm, whereas the thickness L and the slope α (that defines the angle θ) range from 3 to 56 mm, and from 60 to 85 deg., respectively. The outlet width 2w of the hopper is varied from 1.5 to 3 mm. The average diameter d of beads is changed from 30 to 100 μm . We observe the transport of beads through the outlet by taking movies using a video camera  either from the front or lateral side of the cell.The experiment is performed with a cell composed of acrylic plates of thickness 3 mm. The height 2Ffric can be estimated by noting that the pressure inside the granular medium is in the hydrostatic regime  at the the height z, the normal force is given by μ the coefficient of the maximal static friction along the slope α = tan θ and thus the vertical component is given by Ffric applied by the two walls of slope α is given by The force How to cite this article: Yagisawa, Y. et al. Stationary bubble formation and cavity collapse in wedge-shaped hoppers. Sci. Rep.6, 25065; doi: 10.1038/srep25065 (2016).


A systematic review on the use of incentives to promote questionnaire return in clinical trials suggest they are effective, but not all studies have sufficient funds to use them. Promising an incentive once data are returned can reduce the cost-burden of this approach, with possible further cost-savings if the offer were restricted to reminder letters only. This study aimed to evaluate the effect of promising a monetary incentive at first mailout versus a promise on reminder letters only.This was a randomised Study Within A Trial (SWAT) nested within BUMPES, a multicentre randomised controlled trial of maternal position in the late stage of labour in women with an epidural. The follow-up questionnaire asked for information on the women’s health, wellbeing and health service use one year following the birth of their baby. Women who consented to be contacted were randomised to a promise of a monetary incentive at first mailout or a promise on reminder letters only. Women were given an option of completing the questionnaire on paper or on online. The incentive was posted out on receipt of a completed questionnaire. The primary outcome was the overall return rate, and secondary outcomes were the return rate without any chasing from the study office, and the total cost of the vouchers.A total of 1,029 women were randomised, 508 to the first mailout group and 518 to the reminder group. There was no evidence to suggest a difference between groups in the overall return rate (adjusted RR 1.03 (95 % CI 0.96 to 1.11), however the proportion returned without chasing was higher in the first mailout group . The total cost of the vouchers per participant was higher in the first mailout group .Offering a monetary incentive when a reminder is required could be cost-effective depending on the sample size of the study and the resources available to administer the reminder letters.ISRCTN35706297, 26th August 2009.The BUMPES Trial is registered with Current Controlled Trials:  Maximising follow-up rates for postal questionnaires in randomised controlled trials is an important aspect of a well-designed and well conducted study. Loss to follow-up can lead to bias and compromise the internal and external validity of the results.Use of monetary incentives to promote questionnaire return in clinical trials has been researched. Existing systematic reviews suggest they are effective , 2, but This randomised study within a trial (SWAT) was nested within the BUMPES trial, a multicentre randomised controlled trial investigating the effect of maternal position during the late stages of labour in women with an epidural. The SWAT was carried out on a population of women in the UK one year after the birth of their first child and was developed because the return rate of the follow-up questionnaire for BUMPES was lower than expected in the early stages of the trial. Since current evidence on the use of incentives includes a variety of populations, providing an evidence base on the use of incentives for postnatal women will enhance future research methodology in this population.This SWAT aimed to evaluate the effect on the return rate of a 1-year follow-up postal questionnaire, comparing the promise of a monetary incentive at first mailout with a promise on reminder letters only.This parallel group, randomised controlled SWAT nested within BUMPES was conducted on women randomised into the BUMPES study who had not already been sent their 1-year follow-up questionnaire. The questionnaire asked for information on the women’s health, wellbeing and health service use one year following the birth of their baby. Women had the option of completing the paper questionnaire and returning it using a freepost envelope, or completing it on-line using a secure web-interface.Women were included if they were recruited to BUMPES, consented at recruitment to receive the 1-year follow-up questionnaire, and the questionnaire had not already been sent. Women were excluded if they had had a stillbirth, their infant had died by the time of follow-up, their address details were unknown or if they were not living at the same address as their infant.Women were randomly allocated to one of the following two groups: (1) an incentive cover letter sent with the first mailout of the questionnaire containing details of a promise of a £10 gift voucher (redeemable at high street shops) on return of a completed questionnaire. The covering letter included a sentence explaining that the voucher was to thank participants for their time and effort. All reminder letters included a sentence about the incentive; (2) an incentive reminder letter. For this group the cover letter sent at first mailout did not mention the incentive. If the questionnaire was not returned, all reminder letters detailed the promise of a £10 gift voucher on return of a completed questionnaire.For both groups women were additionally contacted electronically and via text message if the contact details were available. The content of the emails and texts sent reflected the group to which the woman was randomised.Allocation was by computer random number generation and stratified by BUMPES allocation and by centre. The randomisation schedule was generated by the National Perinatal Epidemiology Unit Clinical Trials Unit and sent to the BUMPES trial office at the Comprehensive Clinical Trials Unit at University College London via a secure web-link. Randomisation to incentive cover letter at first mailout or incentive reminder letter occurred at each woman’s next follow-up point during the conduct of the BUMPES study. Each BUMPES participant was randomised once only. BUMPES trial staff were aware of the allocation due to the nature of the interventions, and the practicalities involved in sending the letters and the vouchers.The pre-specified primary outcome measure was questionnaire return, defined as receipt of a completed or partially completed questionnaire at the BUMPES office. Pre-specified secondary outcome measures were the number of questionnaires returned without chasing by the study team and the total cost of the vouchers sent out by study arm.Recording of questionnaire receipt, date received and voucher sent was made using internal trial administration systems. Postal versus online receipt was also recorded.The sample size was predetermined by the numbers of questionnaires that remained to be sent at the estimated start time of the SWAT. BUMPES started recruiting in October 2010 and finished in January 2014. A total of 3,236 women were randomised. It was estimated that approximately 1,150 women would remain to be followed up at the start date of this study (beginning August 2014). Assuming that approximately 15 % of these women would be excluded from receiving the questionnaire due to stillbirth, infant death, or address details unknown or different to the infant, 980 women would be eligible to be randomised in the nested study (approximately 490 per group).In order to assess the detectable effect size possible with the given sample size, we estimated the control group risk based on current literature. Khadjesari et al.  investigThe follow-up questionnaire return rate for BUMPES up to June 2014 was 59 %. Assuming that this could increase by at least 5 % with the use of an offer of an incentive either with an incentive cover letter at first mailout or an incentive reminder letter only, a sample size of 980 would be sufficient to demonstrate an increase in questionnaire return of 8 % from 64 % in the reminder group to 72 % in the first mailout group at a two-sided 5 % significance level with 80 % power. A detectable difference of between 8 and 8.5 % would be possible for return rate estimates in the reminder group of between 60 and 70 %.For all analyses, an intention to treat approach was taken and participants were analysed in the groups into which they were randomly allocated, i.e. comparing outcomes for women allocated to the first mailout group with outcomes for women allocated to the reminder group, regardless of allocation received.All analyses were based on all women randomised for whom we had data available.Participants in the two randomised groups are described separately with respect to baseline demographics and clinical characteristics, including the primary outcome for the main BUMPES study, and recorded on the BUMPES Woman and Infant Data Collection Booklet.The return rate and chase rate before the introduction of the randomised interventions (i.e. before the SWAT started) and at the end of the study  is presented using numbers and percentages. The return rate and chase rate by method of completion  is described by trial arm using numbers and percentages.An adjusted analysis was performed on the two return rate outcomes adjusting for centre (the stratification factor at randomisation)  as a ranTo examine whether the effect of when vouchers are sent is consistent across specific subgroups of women, a subgroup analysis by IMD (Index of Multiple Deprivation) quintile was pre-specified. Results are presented as risk ratios plus 95 % CI for each subgroup, by intervention group, with the p value for the statistical test of interaction.Stata/SE for Windows (version 13.1) was used for all analyses.Randomisation to the incentive nested study started on 31st July 2014 and continued until all questionnaires and reminders had been sent (last letter sent 6th March 2015). The total number of women in the SWAT was 1026. Eight women were excluded from all analyses as it was discovered after they had been randomised to the SWAT that they had moved address , diagnosis of pre-eclampsia, and spontaneous vaginal birth (the BUMPES primary outcome) . This trend is also seen in the percentage returned without any reminder letters being sent .For the primary outcome, the percentage of questionnaires returned overall for those in the first mailout group was slightly higher than those in the reminder group (74.2 vs. 71.8 %), but this was not statistically significant at the 5 % level (adjusted risk ratio (RR) 1.03 and 95 % CI 0.96 to 1.11). Women who receive a cover letter promising an incentive at first mailout are more likely to return their questionnaire without a reminder letter being required compared to those receiving a standard cover letter . One in five of all questionnaires returned  were completed online, with slightly fewer being returned online in the first mailout group compared to the reminder group (18.0 vs. 23.0 %). The mean difference in the total cost of the vouchers per participant was £4.56 (95 % CI £4.02 to £5.11), with the cost being higher in the group receiving the incentive cover letter at first mailout , suggesting no differential intervention effect across deprivation quintiles.The pre-specified subgroup analysis is presented as a forest plot in Fig. In this study within a trial, there is no evidence to suggest that an offer of a monetary incentive at first mailout compared to only when a reminder letter is sent makes a substantial difference to the overall return rate of a 1-year follow-up questionnaire. Although there were slightly more questionnaires returned in the group receiving the offer at first mailout (an absolute difference of 3.4 %) the corresponding adjusted risk ratio of 1.03 (95 % CI 0.96 to 1.11) was not statistically significant at the 5 % level.The return rate for women included in the SWAT compared to that before the SWAT was introduced demonstrated a marked improvement (absolute difference 17 %). Although this is not a randomised comparison, it is consistent with that found by Kenyon et al.  in a ranThis SWAT used a £10 high-street gift voucher as a monetary incentive. The mean cost of vouchers per participant was greater in the group receiving the offer at first mailout (£7.50 vs £3.00). Coupled with the lack of evidence of a difference in the overall return rate, this would indicate that sending the offer of an incentive with a reminder letter only is a cost-effective approach to improving return rates. However, there is evidence to suggest that the return rate without requiring reminders is higher in the group for whom the incentive is offered in the first mailout (absolute difference 9.4 %). The cost of administering the additional reminder letters was not calculated, but is a serious consideration that would need to be offset against the expected cost of the vouchers and could depend on the administration resources available in the trial team as well as the sample size of the study.There are ethical issues to consider with the approach of only sending an offer of an incentive to those participants who do not return their questionnaire promptly. Consideration should be given to the chance that participants in a study may communicate with each other, and share their experiences regarding whether or not they received an incentive.This is the first known SWAT to investigate the use of incentives for improving questionnaire return rates in a population of first time mothers with infants around 1 year old. This study suggests that offering a monetary incentive when a reminder is required could be cost-effective depending on the sample size of the study and the resources available to administer the reminder letters.CI, confidence interval; IMD, index of multiple deprivation; IQR, interquartile range; RR, risk ratio; SD, standard deviation; SWAT, study within a trial


International health partnerships are one approach to capacity building in health systems. The evidence base for institutional partnerships for health service development remains weak and evaluation of the process and outcomes of health partnerships is a priority. The variability of partnerships contributes to the challenge of understanding their effectiveness and a typology of partnerships could aid evaluation. We analysed the proposals for all of the partnerships that received funding from the Tropical Health and Education Trust in 2012–2013 to develop such a typology.Our data consisted of 54 successful project proposals for health partnerships funded by THET in 2012–2013. A coding strategy was developed and modified through five rounds of coding, discussion, modification of the coding strategy and re-coding. The final coding strategy classified partnerships according to impact, approach and relationships between partners.All 54 (100 %) of the partnerships in our sample planned to deliver training and 30 (56 %) aimed to deliver infrastructure strengthening in addition to training. 24 (44 %) aimed to build generic skills and 30 (56 %) specialist skills. 33(61 %) of the partners based in low and middle income countries had a scope of influence at national or international level and 33 (61 %) partnerships were between partners with an equal scope of influence. We suggest that those partnerships that focus on infrastructure strengthening and the development of generic skills might have more sustainable impacts in situations of high health care worker mobility and 12/54 partnerships met these criteria.We classified partnerships by their impact ; approach to health systems strengthening  and relationships . This is a first step in generating questions about partnership effectiveness that may be answered through evaluation.The online version of this article (doi:10.1186/s12992-015-0132-x) contains supplementary material, which is available to authorized users. Health partnerships are one approach to capacity building in health systems. They aim to improve health services in low and middle income countries (LMICs) and the UK through long term, sustainable collaborations that involve the reciprocal exchange of skills, knowledge and experience between partners in the UK and overseas . The eviThe Tropical Health & Education Trust (THET) has supported health partnerships for the last 25 years and is currently the managing agent for the Health Partnership Scheme (HPS), a United Kingdom Department of International Development- funded programme for health partnerships. The Health Partnership Scheme has awarded grants to 138 health partnership projects since its inception in 2011. In the first phase of HPS funding (grants awarded in 2012–2013 for projects of one to three years), THET awarded 86 grants across eight different grant streams: Multi-Country Partnerships; Long-Term Volunteering; Pilot Projects; Medium Paired Institutional Partnerships; Large Paired Institutional Partnerships; Volunteer Bursaries; Medical Equipment Partnerships; and Start-up grants. Grants ranged in size from £5000 to start a health partnership to £1.5million for a multi-country partnership.We analysed the proposals of all of the partnerships that received funding from THET in 2012–2013 in 6 out of the 8 grant streams to develop a simple classification of health partnerships as an aid to describing and evaluating this approach. Excluded from the analysis were grants in the categories of Start-up  and Volunteer Bursaries  since the start up grants enable the setup of a partnership relationship only and the volunteer bursaries fund individuals to work within an existing partnership.Our data consisted of 54 of the 56 successful project proposals for health partnerships funded by THET in 2012–2013 out of a total of 378 submissions. Of the two that were not included, one did not accept the grant and the project did not go ahead, the other was excluded for administrative reasons. We used a framework approach to code the data [Once the initial themes were identified through the process of reading and re-reading and the sensitisation of the initial list of themes we generated a coding strategy for each theme that was developed and modified through five rounds of coding, discussion, modification of the coding strategy and re-coding. At key stages of the coding process 20 % of the coded data was checked for consistency by double coding, which was carried out blind by pairs of researchers  with differences resolved through discussion. Detailed inclusion and exclusion criteria for each category were developed. For example the ‘education and training’ category included; ‘side by side training’, mentoring, buddying, clinical specialist training, visits by LMIC partners to UK for education and training and training of trainers but excluded the development of new curriculae. Similarly, the category ‘infrastructure’ included curriculum development, equipment supply, development of protocols and referral pathways and the development of new services. Our final coding framework is described in Table Half of the partnerships planned to have their highest level of focus at an individual level and half at an organisational level as shown in Table All 54 (100 %) of the partnerships in our sample planned to deliver education and training and 30 (56 %) aimed to deliver infrastructure strengthening in addition to training.Twenty-four partnerships focused on generic skills or activities, transferable across a number of health care tasks such as effective hand washing to improve infection control procedures, while 30 focused on specialist skills such as a specific surgical procedure that may be applicable in one context only  had a scope of influence at national or international level, shown in Table  % had a 2 = 0.8, P = >0.3 from chi-squared test. Data are available in Additional file Relative scope allowed us to predict the relative influence of partners in relation to each other, a factor that may influence mutual accountability and collaboration. The majority of partnerships 61 %) were based on equal scope as determined by the level of the institutions involved, such as tertiary referral hospital to tertiary referral hospital, or professional association to professional association, and the job titles of the project leaders. The low income partner was more influential in 11 of the 21 unequal partnerships. Examples are given in Table 1 % were The majority of partnerships, 69 %, managed and delivered interventions directly compared to 22 % who operated with a non-governmental organisation or a charity. Fourteen (26 %) operated across more than one LMIC.We developed a typology of health partnerships and were able to classify all 54 partnerships funded by THET in 2012 using this typology. We completed an inductive analysis starting from descriptions of the partnerships found in their funding applications. The main challenge in this process was to go from the variability in the size, location, clinical specialty and approach of the individual partnerships to a simple classification that identified meaningful differences between partnerships as an aid to comparison and evaluation. Particular challenges included distinguishing between international and national partners as many national organisations will have some activity at an international level, for example ministries of health. To overcome this we categorised based on their day to day activities.Previous attempts to classify health partnerships have described their area of activity. For example, a recent evaluation of the THET health partnership scheme classified partnerships in terms of area of activity, for example direct delivery of health services; health promotion; continuing professional development; under/post graduate education; support services (facilities/equipment/management); research . We aimeWe searched the published literature for alternative approaches to health partnership typologies and while we identified none for international health partnerships we identified two used to classify health partnerships within a single country. Table The data set could have been subject to selection bias as it consisted entirely of proposals that were successful in their applications for funding. Reasons for rejection include non-eligibility; lack of information on application; inappropriate clinical or contextual relevance, unrealistic ambition and feasibility; size of grant not appropriate for level of activity proposed. The only data available to us was that in the funding applications. Some applications were more detailed than others, which could have resulted in misclassification of partnerships where intended activities were not fully described in the application. This work used data on health partnership set-ups and approaches, the next phase will be to develop a theory of change to analyse the extent to which partnerships were able to implement their plans and achieve their objectives.There has been no typology of health partnerships to date that goes beyond area of activity. We propose a typology of health partnerships with categories to describe impact, approach and relationship between partners. There is a lack of published evidence on the effectiveness of institutional partnerships as a strategy for health systems strengthening. This classification is intended to facilitate comparison between partnerships as an aid to evaluation. It is the first phase of a larger project where we will use the typology to select three different partnerships. For each of these we will develop a theory of change and model evaluation plans with the intention of comparing processes and outcomes.


Every year a lot of children die from heat stroke and hyperthermia because they have been left unattended in closed automobiles. These fatalities have augmented slightly in the past decade, but they are a poor recognized type of vehicle injury and little research has been done to discover the circumstances surrounding the fatal event. Two factors make children more prone to hyperthermia than adults: children have a greater surface area body mass ratio than adults and their thermoregulation is less efficient than adults. A scientific explanation about how it can happen that a parent leaves his child unattended in the car could be related to the Working Memory (WM): stress increases interference from irrelevant information, impairing selective attention and WM and influencing behavior. In the last two years in Italy 16 cases of child hyperthermia due to abandonment in motor vehicle were identified. These findings suggest that educational programs and literature for parents regarding automobile safety should include information about the potential dangers of heat stress, in fact, as these events are mostly unintentional, legislative efforts may be vain. Injuries in stationary vehicles for children younger than 14 years old are poorly recognized type of vehicle injury and receive far less attention than motor vehicle crashes. In fact, according to data of the CDC (Centers for disease Control and Prevention), on average 12,175 children from 0 to 19 years of age die each year in the United States from an unintentional injury and the main cause is transportation (most of them because of motor vehicle traffic-related injuries). Two facThe aim of this study is to summarize the circumstances surrounding the fatal event, highlighting the major causes of children death and injuries, trying to explain how it could happen that a caregiver forgets his child and underscoring the need for effective interventions. Furthermore 16 cases of illness or death of children caused by the fact of being left unattended in parked vehicles were identified in Italy.th September, 2012, have been used to identify hyperthermia (heat stroke) deaths of children since 1998 in the United States[Data collected by Null of the San Francisco State University (Department of Geosciences), updated the 25d States. It contst May, 2011 and the 31st August, 2012, using newspaper indexes, news websites and internet searching engines such as Google. Keywords related to heat, motor vehicles, hyperthermia, child, abandonment and enclosure were used. 16 cases were collected and children were defined as aged ≤11 years but in 14 out of 16 cases children were aged ≤3 years. All cases reported occurred in Italy and in our study were enclosed all children , regardless of the outcome. We reported whether children left unattended were intentionally left unattended or not and if the case was unclear. We also looked at where it happened, the cause of the “abandonment” and for how long, the child’s age and the outcome.A second source was a separate internet search for children left by their mother or father in parked vehicles occurring in Italy between 1st of May 2011 and the 31st of August 2012, we identified 16 cases of child hyperthermia due to abandonment in motor vehicle. Table Between the 1Our results are in contrast with Booth et al’s study of 2010 that collected cases between 1999 and 2007 and identified 192 cases of children left unattended: 25 13%) were left unattended intentionally, 145 (75.5%) were unintentionally left unattended and in 22 (11.5%) cases the intentions were unclear[% were leConcerning our study in 13 out of 16 cases the outcome was positive. The mother was responsible for the child at the time of the event in 4 cases, the father in 2 cases and both parents in 9 cases. When evaluating the caretakers liability, there were 18.7% cases where the children were simply forgotten in the car or the caretaker forgot to drop the child off at daycare. Additionally 75% of parents left the child intentionally to go clubbing, to reach their job, to go to the market or to play slot machines in a bar. In a survey performed by Roberts and Roberts, approximately one quarter of interviewed women admitted they left their child in unattended cars[According to these data, one might well ask how it can happen that a parent leaves his child unattended in the car. A scientific explanation could be related to the Working Memory (WM). WM refers to the system or systems that are assumed to be necessary in order to keep things in mind, while performing complex tasks such as reasoning, comprehension and learning. There iSun rays penetrate the glass window of a vehicle, striking the interior and heating exposed surfaces. If the windows are closed, the heat cannot escape and the car will continue to get hot throughout the day. Even on days when the weather is cool but sunny, the interior of the vehicles heats rapidly. FurtherKing et al. indicated that there was a rapid rise in interior temperature with at least 75% of the maximum stabilized temperature being reached within five minutes of closing the doors and maximized within 15 minutes to 51 to 67°C (124-153°F) with significant differences depending on the particular vehicles characteristics. OpeningMcLaren et al. had similar results. In their study 80% of the temperature rise occurred in the first 30 minutes obtaining a maximum at 60 minute.Bouchama and Knochel demonstrated that the first manifestation of heat illness is heat stress, a physical and physiologic strain, next is exhaustion characterized by dehydration and a core temperature reaching 37°C to 40°C and finally heat stroke. Research performed in the past decade has shown that heat stroke results from thermoregulatory failure and an increased acute-phase response with altered expression of heat-shock proteins. Heat stroke is defined clinically as a core body temperature that rises above 40°C and that is accompanied from hot, dry skin and central nervous system abnormalities such as convulsion, delirium or coma. PreviouIt would be interesting to discover how long until the infant experiences adverse effects from a particular heat, but it is difficult to study for ethical reasons.The findings in this report are consistent with other researches that indicate that children left unattended in motor vehicles are at an increased risk of injury and death.Leaving a child alone in a car can be considered a form of neglect. As according to The Child Abuse and Prevention Treatment Act (CAPTA), child abuse and neglect are defined as: “any recent act or failure to act on the part of a parent or caretaker, which results in death, serious physical or emotional harm, sexual abuse, or exploitation, or an act or failure to act which presents an imminent risk of serious harm”. Additionally, what is considered neglect varies based on the age and the developmental level of the child: for instance leaving a child unattended for an hour is considered neglect when the child is young, but not when the child is a teenager.Several areas for possible intervention include education, legislation and regulation. Parents and caretakers should be warned and exhorted not to leave children alone in motor vehicle even for just a few minutes. How often is the quick 10 minutes visit to the supermarket, with children left in the parked car, then converted to 30/40 minutes?Special precaution should be taken with small infants and children during milder and even sunny days, in order to prevent the “greenhouse effect” occurring rapidly in a car where the windows are transparent to solar radiation but opaque to long-wave radiations. Jasni and Nasir found out the tinted windows as an overall good performance in reducing the maximum temperature inside the car because they decrease the transmitted radiations trough the windows. As recoParents could also do something like purchasing a booster seat, writing a note or keeping an object such as a stuffed toy where the driver will notice it before leaving the car or asking the childcare provider to call if the child is not stand out for childcare and avoid to park in a sunny place. However, many parents may not conceive of forgetting their child in a car and even with an incentive could not purchase a system. For this reason a technological solution in which a sensor alerts a caregiver that a child has been left in a car will be the only plausible intervention strategy.According to the 2001–2010 Italian Status Report on Road Safety, road deaths result reduced by 43% in 10 years, after the creation of the “Italian Road Safety Awareness Campaign” started in 2001 with the aim of promoting safety belt use and compliance with speed limits to reduce injuries and deaths from traffic crashes. Consequently we propose the scientific community to start a “Children deaths in parked vehicles awareness Campaign”.Educational programs and literature for parents  regarding automobile safety should include information about the potential dangers of heat stress, in fact, as these events are mostly unintentional, legislative efforts may be vain.The authors declare that they have no competing interests.PF conceived of the study, RR and AC participated in its design and coordination and helped to draft the manuscript. FI and PL, contributed in data collection. FV, OC and VDV performed review of the literature. All authors read and approved the final manuscript.


The yield of radical pair reactions is influenced by magnetic fields well beyond the levels expected from energy considerations. This dependence can be traced back to the microscopic dynamics of electron spins and constitutes the basis of chemical compasses. Here we propose a new experimental approach based on molecular photoswitches to achieve additional control on the chemical reaction and allow short-time resolution of the spin dynamics. Our proposal enables experiments to test some of the standard assumptions of the radical pair model and improves the sensitivity of a paradigmatic model of chemical magnetometer by up to two orders of magnitude. We suggest to connect the radicals via a molecular switch presenting two isomeric forms and capable of undergoing conformational changes upon the absorption of a photon. In this way, one can optically manipulate the distance between the radicals and effectively determine the instant of their re-encounter. Since the chemical reaction takes place at the moment of re-encounter, we achieve control on the reaction kinetics.First, we present the experimental setup and discuss its feasibility with state-of-the-art technology. The consistency of timescales and the efficiency of the procedure are analyzed for the case of azobenzene as the photo-controlled bridge. Second, we show how the additional control can be exploited to improve the performance of sensors based on the RP mechanism, and in particular we apply our scheme to a specific chemical magnetometer to boost its sensitivity by two orders of magnitude.2From the broad class of chemical reactions involving intermediate radicals t. Thus, we are facing a system in which two distinct, but concurrent dynamics are taking place: The quantum evolution of the electron spin state, and the classical diffusion of the molecules kThe number of radical pairs which recombine through the singlet reaction channel is directly proportional to the time integral of the fraction of radicals in a singlet state 3k ∼ 1 ns−1 indicates that most of the geminate re-encounters happen in the first few nanoseconds after the initial electron transfer, and so it becomes hard to study the electron spin dynamics at later times or to observe the dependence of the entanglement lifetime on B as predicted in Ref. k ∼ 1 μs−1. For chemical reactions involving bi-ionic radicals in solution, however, the Coulomb attraction leads to a faster re-encounter. Thus several experimental efforts have been undertaken to modify the distribution of the RP re-encounter time, mainly by imposing constraints on the geometry of the system by linking the radicals with a flexible chain k ∼ 0.1–1 μs−1 essentially determined by properties (like solvent viscosity or chain length) that cannot be changed continuously or even independently, and whose effect on the rate k is not easy to predict quantitatively. To overcome these difficulties, we propose to use optical switches, in this way combining geometrical constraints with the possibility of optically controlling them.A large rate 4The distance of the radicals strongly affects both the possibility of charge recombination and the electron spin dynamics. At small separations, the electron transfer is favored by the proximity of the radicals, while the direct electron–electron coupling inhibits the spin dynamics. In fact, the exchange interaction determines an energy gap between the singlet state and the triplet states which suppresses the spin interconversion. Since such interaction decreases exponentially with increasing distance between the radicals, for the moderate separation reached in bi-ionic reaction in solution they are typically neglected . Azobenzene is an organic molecule that occurs in two isomeric forms, trans and cis azobenzene, having a stretched, respectively contracted, structure. The synthesis of azobenzene derivatives having different chemical functional groups is routinely performed The processes involved in our proposal need to satisfy a hierarchy of timescales: the electron spin dynamics determines the reference timescale to be ∼1–10 ns  with respect to which the spin relaxation (either dissipation or dephasing) and the thermally driven isomerization have to be slow, while the radical creation and photoisomerization mechanism have to be fast. Typically, spin–lattice relaxation takes ∼1–10 μs at room temperature, while photo-excitation of the donor and successive electron transfer happens in a few picoseconds. Radicals were generated by a 7 ns pulse in 6B. Intuitively, the magnetic sensitivity is high when a small change in the magnetic field intensity produces large effects on the singlet yield. Formally, it is defined as:The control of the RP re-encounter probability finds a direct application to improve the performance of chemical devices. Here, we show how a simple-to-implement control scheme highly enhances the sensitivity of a model chemical magnetometer by up to two orders of magnitude. The basic idea behind a chemical magnetometer is that, since a change in the magnetic field modifies the amount of singlet products, one can reverse the reasoning and measure the chemical yield to estimate B field varies around a large ‘off-set’ value, one can reproduce such conditions by applying a suitable external field for compensation. For the realistic choice We evaluate the sensitivity in the regime of long spin–lattice relaxation times and weak magnetic fields, i.e. for When integrated on timescales longer than the effective ‘period’ of the envelope, B is determined by applying pulses of duration k. We observe that similar enhancements are obtained for several The experimental protocol that we suggest is characterized by the sole parameter B to the experimentally observed singlet yield, the function B is inversely proportional to the corresponding magnetic sensitivity A few remarks are necessary. In principle, to associate a unique magnetic field −1. The average sensitivity in the given range amounts to about 25 mT−1 which means that our magnetometer is optimal within a factor of 10. This is remarkable since the proposed pulse sequence is characterized by the sole parameter Finally, let us estimate how the sensitivity in 7We have proposed a new experimental approach which enables the control of the re-encounter probability of radical pairs in solution via light pulses. This allows one to study the electron spin dynamics on the short timescale of its evolution and enlarges the information accessible in spin chemistry experiments. Reducing the stochastic nature of ensemble and time averages will contribute to a better understanding of the radical pair mechanism itself.So far, two types of quantum control schemes have been explored in chemistry. (i) In addition to static magnetic fields, the spin chemistry of radical pairs has been controlled by resonant microwave fields  Regarding technological applications, the proposed experimental scheme offers an approach to increase the sensitivity of man-made magnetic-field sensors based on chemical reactions. This we have demonstrated with a suitable radical pair connected by a photoswitchable bridge. We have presented a simple protocol, which enhances the sensitivity of the chemical magnetometer by up to two orders of magnitude. Remarkably, this scheme can be implemented using weak laser pulses, which have a duration much longer than the timescale given by the electron spin dynamics and, indeed, comparable to the longest one as defined by the weak magnetic field


An endoscopic system is needed that presents informative images irrespective of the surgical situation and the number of degrees of freedom in endoscopic manipulation. This goal may be achieved with a virtual reality view for a region of interest from an arbitrary viewpoint. An endoscopic pseudo-viewpoint alternation system for this purpose was developed and tested.   Surgical experts and trainees from an endoscopic surgery training course at the minimally invasive surgery training center of Kyushu University were enrolled in a trial of a virtual reality system. The initial viewpoint was positioned to approximate the horizontal view often seen in laparoscopic surgery, with    There was a 0.37 mm reduction in total error (   Suturing performance improved with the new virtual reality endoscopic display system. Viewpoint alternation resulted in an overview that improved depth perception and allowed subjects to better aim the marker. This suggests the proposed method offers users better visualization and control in endoscopic surgery. Minimally invasive surgery is attracting attention today. One of the most utilized forms of minimally invasive surgery is laparoscopy, which is carried out by placing multiple trocars through incisions on the abdominal wall and by inserting forceps and an endoscope on the inflated abdominal cavity through the trocars. Surgeons carry out a range of medical treatments under an endoscopic view displayed on a monitor. Laparoscopy is applied to wide range of surgeries including cholecystectomy, prostatectomy and gastrostomy.Laparoscopy requires smaller incisions as compared to conventional surgeries, which lead to fewer traumas, less blood loss, better cosmetics and a shorter stay at hospital . These aAll six degrees of freedom (DoFs) are needed at the tip of an endoscope to position the viewpoint freely. However, owing to the constraints of the trocar, only four DoFs are available with a normal endoscope. Of these four DoFs, two are rotational around the trocar, one is translational along the shaft of the endoscope and one is rotational around the shaft of the endoscope. The rotational DoF around the shaft of the endoscope is not often used because the direction of gravity must remain constant . This meIt is sometimes difficult to position the viewpoint well enough to provide the required information about an intervention site. In that case, the surgeon must reconstruct the view from his/her insight to understand the current state of the site. Since view reconstruction of the intervention site can be difficult, the reconstructed view may be incorrect in some important details.The limited positioning of the viewpoint due to insufficient DoFs of an endoscope forces surgeons to work with their insight. This is a problem because perception through an endoscopic view depends on surgeon skill, which increases the risk of a failure in understanding. The motivation for our study was to expand the reachable viewpoints in laparoscopy.Exchanging straight-viewing endoscope and oblique-viewing endoscope is frequently seen in laparoscopy, allowing surgeons to observe surgical region of interest from a different viewpoint. More reachable viewpoints can be achieved by increasing DoFs at the tip of an endoscope. ENDOCAMELEONinterest .Approaches that employ hardware configurations as mentioned above allow observation of the region of interest from more than one direction without losing superiority of using a rigid endoscope; i.e., high resolution and low latency. However, the approaches that employ hardware configurations lack versatility because reachable viewpoints depend on the configuration of DoFs and on the surgical situation. To ensure an arbitrary orientation in relation to the region of interest, an endoscope requires more than standard set of four DoFs. The number required for an arbitrary viewpoint cannot be predicted because surgical conditions change according to patient body shape, patient diagnosis and surgeon preferences, for example, thus, there are innumerable combinations of conditions. Any increase in DoFs of an endoscope leads to an increase in endoscope diameter, more complicated control mechanisms and higher cost. Because an increase in DoFs by use of hardware is not an optimum solution and that it does not prevent collision of endoscope and tissues, a viewpoint orientation control that does not rely on a mechanical configuration is preferable.To allow non-mechanical vision control, we developed pseudo-viewpoint alternation by use of image processing Fig. . An imagA concept of presenting virtual images as generated from a different viewpoint was proposed by Breedveld et al. . WentinkKoppel et al.  presenteIn this paper, we report viewpoint alternation system with interactive control interface and evaluation of the pseudo-viewpoint alternation method on surgical tasks. In second section, we explain the abstract scheme of an image processing method that applies “pseudo-viewpoint alternation” to images obtained from an endoscope. In third section, we describe the method of a quantitative performance assessment and materials used to implement proposed method. The performance assessment was carried out by comparing task performances with and without the pseudo-viewpoint alternating system. The “Result” of experiment is presented in fourth section and “Discussion” in fifth section.The pseudo-viewpoint alternating system consists of a 3D endoscope, a controller and an image processing unit. The coordinate system is illustrated in Fig. A pinhole camera model is utilized in camera calibration. The endoscope is calibrated to obtain intrinsic parameters and distortion coefficients , 9.Images are deformed to eliminate distortion . 3D coormentclass2pt{minimA 3D field of view is required to apply projection deformation to the images. An acquired 3D point The region of interest must remain in the field of view. This implies that rotation around the region of interest is the ideal control scheme for the viewpoint.A joystick with two analog outputs was implemented as a controller. Input vector nt}Δθ by  and 4)..\documenThe input rotation vector  loop by .5\documeAssuming the origin is the center of endoscope, 3D point Deformed points mentclass2pt{minimThe color vector of the original pixel f pixels . The sysf pixels . Delaunain vitro experiment to examine the effectiveness of our system. Participants in an endoscopic surgery training course at the minimally invasive surgery training center of Kyushu University were asked to perform training tasks with and without the system. To evaluate the effectiveness of the pseudo-viewpoint alternation method, task outcomes with and without the system were compared.We conducted an A suture task in a horizontal endoscope setup was taken as a model case to evaluate the system. Loss of depth perception is problematic where the endoscope is positioned almost parallel to the working area. This type of endoscopic view is seen frequently in surgery deep inside the abdominal cavity such as in Nissen fundoplication. Uniformly spaced suturing is difficult with limited depth perception. Unevenly spaced sutures may result in postoperative complication. Suturing was chosen as the assessment task because suturing outcome reflects competence in surgical operation in general, thus frequently utilized as an assessment task , 13.To introduce the experiment spontaneously, tasks were performed in a setup similar to an endoscopic surgery training course at the minimally invasive surgery training center Fig. . A phantThe phantom was a rubber sheet  as shown in Fig. A charge coupled device (CCD) camera  with fixed focal length lens was used instead of a stereo-endoscope. This CCD camera provides similar view to an endoscope and is used in endoscopic surgery training course where the experiment was carried out. We used the CCD camera to introduce subjects to the experimental environment spontaneously. The CCD camera was positioned according to the judgment of an experienced surgeon such that it resembled the horizontal view often seen in clinical situations. The optical axis made an angle of As stated in “Pseudo-viewpoint alternation” section, 3D shape acquisition was not implemented in this paper. This was because the phantoms had no texture. Stereopsis-based depth acquisition methods utilize differentiation in color for matching, making it inapplicable on the textureless surface. Instead, a set of uniformly distributed 3D points of a phantom was provided to the system in each processing loop. Resolution of the 3D points was 0.2 sample points per mm which was equivalent to dot pitch of 5 mm.The joystick controller was placed on the forceps grip to allow control of the pseudo-viewpoint alternation. Coefficient ent}γ in  was set nt}αi in  were setnt}αi in  and 8),,\documenent}r in  was set We previously reported that the system recorded at an average frame rate of 7.0 frames per second with a maximum 1.00 mm rendering error excluding the 3D shape acquisition . Frame r1st task: Subjects in group A started a task with pseudo-viewpoint alternation enabled and group B with it disabled.2nd task: Subjects in group A then carried out a task with pseudo-viewpoint alternation disabled and group B with it enabled.Subjects were allocated randomly into groups A and B. Both groups practiced with pseudo-viewpoint alternation enabled. They were allowed to practice until they were satisfied that they understood the experimental tasks and the joystick control. No subject practiced for more than 10 min.A suturing task in the endoscopic surgery training courses at the minimally invasive surgery training center was used. Subjects were to pick up and hold needles in their right hand. Then subjects were to suture from right to left. Subjects were to aim at the dots printed on the rubber sheet and were asked to perform sutures as precisely as possible. Cut up time was 5 min but time was extended when (a) no suture was completed or (b) the subject was engaged in suturing, i.e., the needle was in contact with the rubber sheet.Nine subjects participated in the experiment. Surgical experience and the grouping of subjects are shown in Table The aim of the experiment and the task were explained thoroughly to the subjects before they started the experiment. Subjects were assured that the data would be used in a form that revealed no personal information that would identify individuals. No physical or mental risk was present in the experiment.Rubber sheets were photographed with a high-resolution digital camera with a chessboard marker placed on the rubber sheet after the experiment. The images were digitally deformed by a projection transformation such that the chessboard looked uniform. This transformation was used to compensate for the horizontal slant of the camera. Points of needle insertion and extraction were identified and located manually under magnified view. A suture error was measured from the center of a round mark to the position of insertion/extraction Fig. . In thisSubjects completed at least one suture up to the maximum of six sutures. The Mann–Whitney U test was used to test the difference between conditions with level of significance set Median errors for all sutures with and without pseudo-viewpoint alternation enabled are compared in Fig. There was a notable difference in trend between experts and novices. There is a 0.65 mm reduction in median error for experts compared to a 0.16 mm reduction for novices. Error reduction in the expert class was statistically significant . Group B, which started tasks with system disabled, had median suturing error of 0.85 mm without system and 0.47 mm with system (45 % reduction). Inter-group comparison was statically significant in both conditions (Mode and median of pseudo-viewpoint alternation are shown in Table t}∘ Fig. b. The ext}∘ Fig. a.The number of completed sutures and time taken by each subject to make the first suture is shown in Table No subjects reported existence of latency. Few subjects reported discomfort in needle insertion caused by rendering error on needle. No subject reported existence of rendering error on marks printed on rubber sheet.We observed an improvement in suturing error with the system. This is because alternation of the viewpoint resulted in an overlooking view which helped depth perception and allowed subjects to aim the marker better. This suggests that the proposed method offers users a sense of reality to the generated view.We have expected the improvement be greater on the y-axis, but reduction in error was greater on the x-axis. This is because surgeons do not align the position of needle as, for example, an industrial machinery would do; align x-axis first then y-axis next. Instead, surgeons align the position of needle in both axes spontaneously. This suggests that improving spatial perception in one direction could improve task accuracy in both the improved direction and the orthogonal direction.Experts benefited more from pseudo-viewpoint alternation than novices did. The task prevented inexperienced surgeons from benefiting from pseudo-viewpoint alternation because it was more difficult for them to insert a needle at the desired point than for them to perceive the position for inserting the needle. Because there were only three novices, difference between experts and novices needs to be re-examined after evaluating the system with bigger number of novice subjects.Inter-group difference observed in this experiment was derived from difference in average skill level in the two groups, not from learning curve. This is because inter-group differences were significant on suturing error both with and without system. More subjects are needed to compare the effect of learning curve.Average alternation angle was 14Rendering error of the needle was problematic, as surgeons perceive needle direction from needle shape. Rendering error on the needles occurred because the current implementation assumed the needle and the forceps are on the same plane as rubber sheet. 3D points for the needle and the forceps were not provided as 3D shape acquisition was not implemented. Rendering errors on the needle and the forceps became large when the planar assumption did not hold.To apply the system to the clinical field and to improve rendering error on the needle and the forceps, 3D shape acquisition needs to be implemented. There is accumulated knowledge on 3D shape acquisition that is applicable to laparoscopy . StereopIn the experiment, we substituted 3D shape acquisition by providing system every processing loop a set of uniformly distributed 3D points. We assumed that 3D points are uniformly distributed, but the assumption may not hold for actual clinical cases. Delaunay triangulation is capable providing well-formed meshing even for irregular distribution of points, but assessment is needed to evaluate how the quality of 3D shape acquisition methods affects the overall image quality.To allow non-mechanical vision control, we introduced pseudo-viewpoint alternation using image processing. In this paper, we reported the evaluation of the effectiveness of this method by comparing task performances with and without pseudo-viewpoint alternation. A typical suturing task was used in the evaluation. The distance from the center of a dot that defined the ideal needle entry and extraction points was measured as error. With use of our system, error was reduced by 0.37 mm (The current system is limited in that 3D shape acquisition was not implemented. In future work, a 3D shape acquisition algorithm will be implemented.


The importance of studying associations between socio-economic position and health has often been highlighted. Previous studies have linked the prevalence and severity of lung disease with national wealth and with socio-economic position within some countries but there has been no systematic evaluation of the association between lung function and poverty at the individual level on a global scale. The BOLD study has collected data on lung function for individuals in a wide range of countries, however a barrier to relating this to personal socio-economic position is the need for a suitable measure to compare individuals within and between countries. In this paper we test a method for assessing socio-economic position based on the scalability of a set of durable assets , and compare its usefulness across countries of varying gross national income per capita.s = 0.91, p = 0.002). The same set of assets conformed to a scale in 7 out of the 8 countries, the remaining country being Saudi Arabia where most respondents owned most of the assets. There was good consistency in the rank ordering of ownership of the assets in the different countries . Scores on the Mokken scale were highly correlated with scores developed using principal component analysis (rs = 0.977).Ten out of 15 candidate asset questions included in the questionnaire were found to form a Mokken type scale closely associated with GNI per capita (Spearman’s rank rMokken scaling is a potentially valuable tool for uncovering links between disease and socio-economic position within and between countries. It provides an alternative to currently used methods such as principal component analysis for combining personal asset data to give an indication of individuals’ relative wealth. Relative strengths of the Mokken scale method were considered to be ease of interpretation, adaptability for comparison with other datasets, and reliability of imputation for even quite large proportions of missing values. Studying associations between health outcomes and socio-economic position is an important aspect of health research . A measuThe Burden of Obstructive Lung Disease (BOLD) study is an international survey of ventilatory function  which haA barrier to achieving this is the lack of an easily applicable measure of socio-economic position that is broadly relevant to many countries and that discriminates between individuals as well as between regions or countries. No method will capture all aspects of socio-economic position but asset-based measures have been widely used in low and middle income countries because they provide an easily collected variable that is stable over short term economic fluctuations . The usuIn order to establish a measurement of socio-economic position that could be used to compare individuals within and between countries, we used a Mokken scale approach to develop scores using an inventory of assets included in the BOLD study. This was comprised of commonly used items selected from a number of survey instruments and from experience in an attempt to cover a wide range of levels of affluence with relatively few items. In this analysis we examined whether the answers were scalable, i.e. whether the assets tend to be acquired in the same order by different people and all people with a given number of assets tend to have the same set of assets . We compThe BOLD study has been described in detail elsewhere . BrieflyA total of 8910 subjects were randomly selected in the eight countries. Of these 1863 did not provide responses, mainly due to unavailability or untraceability (51 %). Other reasons were refusal to participate (22 %), deceased (0.5 %), ineligible due to age (7 %) or incomplete data collection (19 %). Sixty-one (0.9 %) out of the 7047 respondents had a missing response to at least one of the asset questions and were also excluded from the analyses. Characteristics of those included are given in Table We first developed a scale using item response theory based on the idea that the items formed a hierarchy such that ownership of any of the assets implied ability to own all the items lower in the order. The method used was a non-parametric model attributed to Mokken  which dij) and for the scale as a whole (H). The usual interpretation is that 0.3 ≤ H<0.4 implies a weak scale, 0.4 ≤ H<0.5 a medium scale and ≥0.5 a strong scale, whilst scales with H < 0.3 do not satisfy a Mokken scale  each country’s IRC was compared with that for all other countries combined using the Mantel–Haenszel test , and theScores and Loevinger’s H coefficients were also calculated for the same selected set of assets when the respondent was 5 years old, excluding cell phones as these were not available at that time. Only individuals with complete data for childhood ownership of the remaining selected assets were included. Equivalent scores, excluding cell phone, were calculated for the current asset data for comparison. Scores for current and childhood ownership of the assets were compared graphically.s). Whilst we did not have any direct measure of individual wealth we assessed the face validity of the scale by determining the direction of the rank correlation between the scores and a number of variables collected for each respondent which we expected to be broadly related to socio-economic position, particularly in low and middle income countries. The variables studied were the highest level of education completed by the respondent and his/her father and mother, height, body mass index (BMI), frequency of someone in the household going hungry for lack of money, and number of people per room in their household.In order to check whether the scores given by our scale were related to wealth we plotted the individual and country mean scores against the GNI per capita  of the cTo compare socio-economic position using data collected in different surveys it may sometimes be necessary to exclude items from the scale. In some circumstances it may also be desirable to include the same set of items in all countries, even though they are not related to socio-economic position in all of the populations. To examine the robustness of the scale to these scenarios we plotted cumulative distribution curves for the scores when one of the questions (cell phone) was omitted and also when an additional random item [~Bernoulli (0.5)] was included. We also assessed the usefulness of an imputation procedure for missing values. This procedure first orders the items according to overall prevalence in the data. The algorithm then imputes a positive response for a missing value if the individual gave a positive response for the following (more common) item, else a negative response if he/she gave a negative response for the preceding (less common) item. If the value to be imputed cannot be determined in this way it is calculated from the relative numbers of positive and negative responses the individual gave for higher and lower items in the scale . Five, 1Finally we used PCA to develop scores from the assets, using both the full list of 15 assets and the 10 assets selected for the Mokken scale. We compared the individuals’ scores on the first principal component derived from these two PCA analyses with the individual Mokken scale scores, and country mean scores for all three methods with GNI per capita, using Spearman’s rank correlation coefficients.msp and imputemok [All analyses were carried out using Stata v13.1, . Selection of items for inclusion in the Mokken scale and imputation of missing values were carried out using the user-written add-on commands in Stata, mputemok , 18.j) were all greater than 0.44 and the overall H coefficient was 0.70, indicating that the items formed a strong scale. This is shown graphically for the selected assets in Fig. From the original list of 15 assets thought to be related to socio-economic position, the AISP selected 10 assets for inclusion in the Mokken scale Table . Loevingj coefficients were only >0.3 for all of the assets in two of the eight countries (Nigeria and Albania), suggesting that some items did not contribute useful information on socio-economic position in some countries. However, overall H coefficients for strength of the scale were >0.3 (i.e. acceptable) for all of the countries except Saudi Arabia.All of the assets showed significant DIF when compared between countries (p < 0.001). Figure s = 0.905, p = 0.002), but with a considerable range of scores in all but the richest countries. When compared with other variables collected for each individual which we expected to be associated with socio-economic position, highest level of schooling was positively and statistically significantly correlated with Mokken scale scores in all countries (p < 0.05)  Table . Mother Using the data on childhood ownership of the selected assets (excluding cell phone) the H coefficient was 0.70 indicating strong scalability also amongst these data. There was a general increase in the number of household assets owned in adulthood compared with childhood with only a small number of respondents having fewer assets in adulthood Fig. . The numSensitivity analyses showed that removing an item from the scale or adding an item uncorrelated to socio-economic position had little effect on the cumulative distribution of scores Fig. . Individs = 0.977; 10 items, rs = 0.996). As for the Mokken scale scores, mean PCA scores for each country showed strong rank correlation with GNI per capita . The association between the gross national wealth and the mean participant asset index measured by either the Mokken Scale or by PCA was essentially the same.Scores on the Mokken scale comprised of 10 assets were compared with scores on the first principal component obtained from PCA using either all 15 of the original assets, or just the 10 assets included in the Mokken scale. In both cases the PCA scores were very highly correlated with the Mokken scale scores  of the 15 assets included in the questionnaire could be incorporated into a single scale such that the mean number of items owned was closely related to wealth as shown by the GNI per capita of the country. There was a high degree of consistency in the rank ordering of percent ownership of these items across countries, and the same set of assets was found to be at least weakly scalable in all of the study countries except the richest, Saudi Arabia, where most people owned most of the assets. Ownership of the set of assets also demonstrated an appreciable improvement in living standards for most people since the time they were aged five, as one might expect.The set of assets used in this study were similar to those used in many other studies . AlthougPCA has become a widely used method for estimating people’s socio-economic position rankings from an asset based inventory , 19–22. Zinn et al.  applied In this study we found statistically significant differences in item functioning (DIF) implying that for people with the same score (which we considered to be a proxy for socio-economic position) the probability of owning any particular asset differed to some extent between countries. Whist this would preclude reliable comparisons of socio-economic position based on any particular asset, the score as a whole is a function of ownership of a set of assets which were acquired with a similar order of ability or preference in all of the countries.We did not have any direct measure of socio-economic position at the individual or household level with which to compare the range of scores within countries. However we found positive correlations in most countries between the individuals’ scores and other variables collected for each respondent that might be expected to increase with increasing socio-economic positon . Conversely negative correlations were found between Mokken scale scores and the number of people per room in the house and the frequency of going hungry for lack of money as might be expected for a scale related to socio-economic position.Despite the simplicity of Mokken scales, their ease of interpretation and apparent near equivalence to PCA, their uptake may have been hindered by a lack of familiarity or availability of suitable software. However routines are now readily available for Stata, R, SAS and other specialist software. The Mokken scaling software includes an automated item selection procedure and tests for goodness of fit so that a suitable set of assets can be chosen from amongst a longer list of candidate questions. For maximum efficiency, therefore, a list of potential questions might be included in a pilot survey and the list shortened accordingly before the main survey. Specialist software is only required for the development and testing of scales. Scoring an individual on an established scale is simply a matter of counting the number of the items that they own.Mokken scaling provides a potentially useful way of assessing wealth on an ordinal scale and hence of testing whether health outcomes are related to socio-economic position. It could be used to distinguish rich from poor across a wide range of settings and therefore to help target healthcare where it is most needed. Reidpath and Ahmadi  highlighSince previous work had shown that GNI per capita had the greatest effect on lung function amongst the poorest countries , the assUse of a Mokken scale appears to be very similar to PCA in its ability to discriminate between people of different socio-economic position but may have advantages in interpretability, adaptability and robustness to variations in the scale or missing data. Now that appropriate software is readily available its use should be considered as a possible alternative to other methods where it is required to rank individuals’ socio-economic position on the basis of an asset inventory.