Influence of temperature on prevalence of health and welfare conditions in pigs: time-series analysis of pig abattoir inspection data in England and Wales.

The prevalence of many diseases in pigs displays seasonal distributions. Despite growing concerns about the impacts of climate change, we do not yet have a good understanding of the role that weather factors play in explaining such seasonal patterns. In this study, national and county-level aggregated abattoir inspection data were assessed for England and Wales during 2010-2015. Seasonally-adjusted relationships were characterised between weekly ambient maximum temperature and the prevalence of both respiratory conditions and tail biting detected at slaughter. The prevalence of respiratory conditions showed cyclical annual patterns with peaks in the summer months and troughs in the winter months each year. However, there were no obvious associations with either high or low temperatures. The prevalence of tail biting generally increased as temperatures decreased, but associations were not supported by statistical evidence: across all counties there was a relative risk of 1.028 (95% CI 0.776-1.363) for every 1 °C fall in temperature. Whilst the seasonal patterns observed in this study are similar to those reported in previous studies, the lack of statistical evidence for an explicit association with ambient temperature may possibly be explained by the lack of information on date of disease onset. There is also the possibility that other time-varying factors not investigated here may be driving some of the seasonal patterns.

Fuels, power and chemical periodicity.

The insatiable-and ever-growing-demand of both the developed and the developing countries for power continues to be met largely by the carbonaceous fuels comprising coal, and the hydrocarbons natural gas and liquid petroleum. We review the properties of the chemical elements, overlaid with trends in the periodic table, which can help explain the historical-and present-dominance of hydrocarbons as fuels for power generation. However, the continued use of hydrocarbons as fuel/power sources to meet our economic and social needs is now recognized as a major driver of dangerous global environmental changes, including climate change, acid deposition, urban smog and the release of many toxic materials. This has resulted in an unprecedented interest in and focus on alternative, renewable or sustainable energy sources. A major area of interest to emerge is in hydrogen energy as a sustainable vector for our future energy needs. In that vision, the issue of hydrogen storage is now a key challenge in support of hydrogen-fuelled transportation using fuel cells. The chemistry of hydrogen is itself beautifully diverse through a variety of different types of chemical interactions and bonds forming compounds with most other elements in the periodic table. In terms of their hydrogen storage and production properties, we outline various relationships among hydride compounds and materials of the chemical elements to provide some qualitative and quantitative insights. These encompass thermodynamic and polarizing strength properties to provide such background information. We provide an overview of the fundamental nature of hydrides particularly in relation to the key operating parameters of hydrogen gravimetric storage density and the desorption/operating temperature at which the requisite amount of hydrogen is released for use in the fuel cell. While we await the global transition to a completely renewable and sustainable future, it is also necessary to seek CO2 mitigation technologies applied to the use of fossil fuels. We review recent advances in the strategy of using hydrocarbon fossil fuels themselves as compounds for the high capacity storage and production of hydrogen without any CO2 emissions. Based on these advances, the world may end up with a hydrogen economy completely different from the one it had expected to develop; remarkably, with 'Green hydrogen' being derived directly from the hydrogen-stripping of fossil fuels. This article is part of the theme issue 'Mendeleev and the periodic table'.

Determining GaN Nanowire Polarity and its Influence on Light Emission in the Scanning Electron Microscope.

The crystal polarity of noncentrosymmetric wurtzite GaN nanowires is determined nondestructively in the scanning electron microscope using electron backscatter diffraction (EBSD). The impact of the nanowire polarity on light emission is then investigated using cathodoluminescence (CL) spectroscopy. EBSD can determine polarity of noncentrosymmetric crystals by interrogating differences in the intensity distribution of bands of the EBSD pattern associated with semipolar planes. Experimental EBSD patterns from an array of GaN nanowires are compared with theoretical patterns produced using dynamical electron simulations to reveal whether they are Ga- or N-polar or, as in several cases, of mixed polarity. CL spectroscopy demonstrates the effect of the polarity on light emission, with spectra obtained from nanowires of known polarity revealing a small but measurable shift (≈28 meV) in the GaN near band edge emission energy between those with Ga and N polarity. We attributed this energy shift to a difference in impurity incorporation in nanowires of different crystal polarity. This approach can be employed to nondestructively identify polarity in a wide range of noncentrosymmetric nanoscale material systems and provide direct comparison with their luminescence.

Student perspectives on using egocentric video recorded by smart glasses to assess communicative and clinical skills with standardised patients.

INTRODUCTION: This exploratory study evaluated student perceptions of their ability to self- and peer assess (i) interpersonal communication skills and (ii) clinical procedures (a head and neck examination) during standardised patient (SP) interactions recorded by Google Glass compared to a static camera. METHODS: Students compared the Google Glass and static camera recordings using an instrument consisting of 20 Likert-type items and four open- and closed-text items. The Likert-type items asked students to rate how effectively they could assess specific aspects of interpersonal communication and a head and neck examination in these two different types of recordings. The interpersonal communication items included verbal, paraverbal and non-verbal subscales. The open- and closed-text items asked students to report on more globally the differences between the two types of recordings. Descriptive and inferential statistical analyses were conducted for all survey items. An inductive thematic analysis was conducted to determine qualitative emergent themes from the open-text questions. RESULTS: Students found the Glass videos more effective for assessing verbal (t22 = 2.091, P = 0.048) and paraverbal communication skills (t22 = 3.304, P = 0.003), whilst they reported that the static camera video was more effective for assessing non-verbal communication skills (t22 = -2.132, P = 0.044). Four principle themes emerged from the students' open-text responses comparing Glass to static camera recordings for self- and peer assessment: (1) first-person perspective, (2) assessment of non-verbal communication, (3) audiovisual experience and (4) student operation of Glass. DISCUSSION AND CONCLUSION: Our findings suggest that students perceive that Google Glass is a valuable tool for facilitating self- and peer assessment of SP examinations because of students' perceived ability to emphasise and illustrate communicative and clinical activities from a first-person perspective.

The vascular Ca2+-sensing receptor regulates blood vessel tone and blood pressure.

The extracellular calcium-sensing receptor CaSR is expressed in blood vessels where its role is not completely understood. In this study, we tested the hypothesis that the CaSR expressed in vascular smooth muscle cells (VSMC) is directly involved in regulation of blood pressure and blood vessel tone. Mice with targeted CaSR gene ablation from vascular smooth muscle cells (VSMC) were generated by breeding exon 7 LoxP-CaSR mice with animals in which Cre recombinase is driven by a SM22α promoter (SM22α-Cre). Wire myography performed on Cre-negative [wild-type (WT)] and Cre-positive (SM22α)CaSR(Δflox/Δflox) [knockout (KO)] mice showed an endothelium-independent reduction in aorta and mesenteric artery contractility of KO compared with WT mice in response to KCl and to phenylephrine. Increasing extracellular calcium ion (Ca(2+)) concentrations (1-5 mM) evoked contraction in WT but only relaxation in KO aortas. Accordingly, diastolic and mean arterial blood pressures of KO animals were significantly reduced compared with WT, as measured by both tail cuff and radiotelemetry. This hypotension was mostly pronounced during the animals' active phase and was not rescued by either nitric oxide-synthase inhibition with nitro-l-arginine methyl ester or by a high-salt-supplemented diet. KO animals also exhibited cardiac remodeling, bradycardia, and reduced spontaneous activity in isolated hearts and cardiomyocyte-like cells. Our findings demonstrate a role for CaSR in the cardiovascular system and suggest that physiologically relevant changes in extracellular Ca(2+) concentrations could contribute to setting blood vessel tone levels and heart rate by directly acting on the cardiovascular CaSR.

Road traffic injuries to children during the school commute in Hyderabad, India: cross-sectional survey.

BACKGROUND: India is motorising rapidly. With increasing motorisation, road traffic injuries are predicted to increase. A third of a billion children travel to school every day in India, but little is known about children's safety during the school commute. We investigated road traffic injury to children during school journeys. METHODS: We conducted a cross-sectional survey in Hyderabad using a two-stage stratified cluster sampling design. We used school travel questionnaires to record any road injury in the past 12 months that resulted in at least 1 day of school missed or required treatment by a doctor or nurse. We estimated the prevalence of road injury by usual mode of travel and distance to school. RESULTS: The total sample was 5842 children, of whom 5789 (99.1%) children answered the question on road injury. The overall prevalence of self-reported road injury in the last 12 months during school journeys was 17% (95% CI 12.9% to 21.7%). A higher proportion of boys (25%) reported a road injury than girls (11%). There was a strong association between road injury, travel mode and distance to school. Children who cycled to school were more likely to be injured compared with children who walked (OR 1.5; 95% CI 1.2 to 2.0). Travel by school bus was safer than walking (OR 0.5; 95% CI 0.3 to 0.9). CONCLUSIONS: A sixth of the children reported a road traffic injury in the past 12 months during school journeys in Hyderabad. Injury prevention interventions should focus on making walking and cycling safer for children.

How do children travel to school in urban India? A cross-sectional study of 5,842 children in Hyderabad.

BACKGROUND: Millions of children travel to school every day in India, yet little is known about this journey. We examined the distribution and determinants of school travel in Hyderabad, India. METHODS: We conducted a cross-sectional survey using a two-stage stratified cluster sampling design. School travel questionnaires were used to collect data from children aged 11-14 years, attending private, semi-private and government funded schools in Hyderabad. We used Google Earth to estimate the distance from home to school for each child and modelled the relationship between distance to school and mode of travel, adjusting for confounders. RESULTS: Forty five of the 48 eligible schools that were selected agreed to participate, providing a total sample of 5842 children. The response rate was 99 %. Most children walked (57 %) or cycled (6 %) to school but 36 % used motorised transport (mostly bus). The proportion using motorised transport was higher in children attending private schools (41 %) than in those attending government schools (24 %). Most (90 %) children lived within 5km of school and 36 % lived within 1km. Greater distance to school was strongly associated with the use of motorised transport. Children living close to school were much more likely to walk or cycle. CONCLUSIONS: Most children in Hyderabad walk (57 %) or cycle (6 %) to school. If these levels are to be maintained, there is an urgent need to ensure that walking and cycling are safe and pleasant. Social policies that decrease distances to school could have a large impact on road traffic injuries, air pollution, and physical activity levels.

Ultrasound-assisted nonviral gene transfer of AQP1 to the irradiated minipig parotid gland restores fluid secretion.

Xerostomia is a common side effect of ionizing radiation used to treat head and neck cancer. A groundbreaking Phase I human clinical trial using Adenoviral gene transfer of Aquaporin-1 (AQP1) to a single salivary gland of individuals suffering from radiation-induced xerostomia has recently been reported. Unfortunately, the limitations of the Adenoviral vector system used in this pioneering trial preclude its advancement to a Phase II trial, and we have thus undertaken to evaluate the therapeutic potential of ultrasound-assisted nonviral gene transfer (UAGT) as an alternative means of delivering AQP1 gene therapy to the salivary gland by comparing head-to-head with the canonical Adenoviral vector in a swine model. Swine irradiated unilaterally with a 10-Gy electron beam targeted at the parotid gland suffered from significant, sustained hyposalivation that was bilateral, despite irradiation being confined to the targeted gland. Unilateral AQP1 gene therapy with UAGT resulted in bilateral restoration of stimulated salivary flow at 48 h and 1 week post treatment (1.62±0.48 ml and 1.87±0.45 ml) to preinjury levels (1.34±0.14 ml) in a manner comparable to Adenoviral delivery (2.32±0.6 ml and 1.33±0.97 ml). UAGT can replace the Adenoviral vector as a means of delivering AQP1 gene therapy in the irradiated swine model, and it is a candidate for advancement to a Phase I human clinical trial.

Local adaptation at range edges: comparing elevation and latitudinal gradients.

Local adaptation at range edges influences species' distributions and how they respond to environmental change. However, the factors that affect adaptation, including gene flow and local selection pressures, are likely to vary across different types of range edge. We performed a reciprocal transplant experiment to investigate local adaptation in populations of Plantago lanceolata and P. major from central locations in their European range and from their latitudinal and elevation range edges (in northern Scandinavia and Swiss Alps, respectively). We also characterized patterns of genetic diversity and differentiation in populations using molecular markers. Range-centre plants of P. major were adapted to conditions at the range centre, but performed similarly to range-edge plants when grown at the range edges. There was no evidence for local adaptation when comparing central and edge populations of P. lanceolata. However, plants of both species from high elevation were locally adapted when compared with plants from high latitude, although the reverse was not true. This asymmetry was associated with greater genetic diversity and less genetic differentiation over the elevation gradient than over the latitudinal gradient. Our results suggest that adaptation in some range-edge populations could increase their performance following climate change. However, responses are likely to differ along elevation and latitudinal gradients, with adaptation more likely at high-elevation. Furthermore, based upon these results, we suggest that gene flow is unlikely to constrain adaptation in range-edge populations of these species.

Catalytic dehydrogenation of propane by carbon dioxide: a medium-temperature thermochemical process for carbon dioxide utilisation.

The dehydrogenation of C3H8 in the presence of CO2 is an attractive catalytic route for C3H6 production. In studying the various possibilities to utilise CO2 to convert hydrocarbons using the sustainable energy source of solar thermal energy, thermodynamic calculations were carried out for the dehydrogenation of C3H8 using CO2for the process operating in the temperature range of 300-500 °C. Importantly, the results highlight the enhanced potential of C3H8 as compared to its lighter and heavier homologues (C2H6 and C4H10, respectively). To be utilised in this CO2 utilisation reaction the Gibbs free energy (ΔrGθm) of each reaction in the modelled, complete reacting system of the dehydrogenation of C3H8 in the presence of CO2 also indicate that further cracking of C3H6 will affect the ultimate yield and selectivity of the final products. In a parallel experimental study, catalytic tests of the dehydrogenation of C3H8 in the presence of CO2 over 5 wt%-Cr2O3/ZrO2 catalysts operating at 500 °C, atmospheric pressure, and for various C3H8 partial pressures and various overall GHSV (Gas Hourly Space Velocity) values. The results showed that an increase in the C3H8 partial pressure produced an inhibition of C3H8 conversion but, importantly, a promising enhancement of C3H6 selectivity. This phenomenon can be attributed to competitive adsorption on the catalyst between the generated C3H6 and inactivated C3H8, which inhibits any further cracking effect on C3H6 to produce by-products. As a comparison, the increase of the overall GHSV can also decrease the C3H8 conversion to a similar extent, but the further cracking of C3H6 cannot be limited.

Widespread phenotypic and genetic divergence along altitudinal gradients in animals.

Altitudinal gradients offer valuable study systems to investigate how adaptive genetic diversity is distributed within and between natural populations and which factors promote or prevent adaptive differentiation. The environmental clines along altitudinal gradients tend to be steep relative to the dispersal distance of many organisms, providing an opportunity to study the joint effects of divergent natural selection and gene flow. Temperature is one variable showing consistent altitudinal changes, and altitudinal gradients can therefore provide spatial surrogates for some of the changes anticipated under climate change. Here, we investigate the extent and patterns of adaptive divergence in animal populations along altitudinal gradients by surveying the literature for (i) studies on phenotypic variation assessed under common garden or reciprocal transplant designs and (ii) studies looking for signatures of divergent selection at the molecular level. Phenotypic data show that significant between-population differences are common and taxonomically widespread, involving traits such as mass, wing size, tolerance to thermal extremes and melanization. Several lines of evidence suggest that some of the observed differences are adaptively relevant, but rigorous tests of local adaptation or the link between specific phenotypes and fitness are sorely lacking. Evidence for a role of altitudinal adaptation also exists for a number of candidate genes, most prominently haemoglobin, and for anonymous molecular markers. Novel genomic approaches may provide valuable tools for studying adaptive diversity, also in species that are not amenable to experimentation.

Novel alkali earth borohydride Sr(BH4)2 and borohydride-chloride Sr(BH4)Cl.

Two novel alkali earth borohydrides, Sr(BH4)2 and Sr(BH4)Cl, have been synthesized and investigated by in-situ synchrotron radiation powder X-ray diffraction (SR-PXD) and Raman spectroscopy. Strontium borohydride, Sr(BH4)2, was synthesized via a metathesis reaction between LiBH4 and SrCl2 by two complementary methods, i.e., solvent-mediated and mechanochemical synthesis, while Sr(BH4)Cl was obtained from mechanochemical synthesis, i.e., ball milling. Sr(BH4)2 crystallizes in the orthorhombic crystal system, a = 6.97833(9) Å, b = 8.39651(11) Å, and c = 7.55931(10) Å (V = 442.927(10) Å(3)) at RT with space group symmetry Pbcn. The compound crystallizes in α-PbO2 structure type and is built from half-occupied brucite-like layers of slightly distorted [Sr(BH4)6] octahedra stacked in the a-axis direction. Strontium borohydride chloride, Sr(BH4)Cl, is a stoichiometric, ordered compound, which also crystallizes in the orthorhombic crystal system, a = 10.8873(8) Å, b = 4.6035(3) Å, and c = 7.4398(6) Å (V = 372.91(3) Å(3)) at RT, with space group symmetry Pnma and structure type Sr(OH)2. Sr(BH4)Cl dissociates into Sr(BH4)2 and SrCl2 at ~170 °C, while Sr(BH4)2 is found to decompose in multiple steps between 270 and 465 °C with formation of several decomposition products, e.g., SrB6. Furthermore, partly characterized new compounds are also reported here, e.g., a solvate of Sr(BH4)2 and two Li-Sr-BH4 compounds.

Evidence on delay in sexual initiation, multiple partnerships and condom use among young people: review of Caribbean HIV behavioural studies.

OBJECTIVE: To develop a Caribbean regional profile of youth sexual behaviour associated with risk of HIV. DESIGN AND METHODS: A review of sexual behaviour surveys with youth aged 15-24 years was conducted as part of the Pan American Health Organization (PAHO) HIV Caribbean Office's Review and Gender Analysis of Caribbean HIV Behavioural and Seroprevalence Studies. Studies with internationally recommended indicators were prioritized. Studies were sought via database searches and contact with researchers and National AIDS Programmes. RESULTS: Inter-country comparisons and longitudinal analyses were limited by lack of uniformity in study age groups and indicators. Data were sufficient to identify the following among 15-24-year olds: .More males than females report sexual intercourse before the age of 15 years. .More than half of sexually active youth report sex before age 16 years. .First sexual encounter is usually with someone older, with age differences larger for females. .More males than females report multiple partnerships, with 20%-76% of males reporting this in the past year. .Condom use varies widely, with no clear pattern by gender. CONCLUSION: There are substantial levels of early sexual initiation, intergenerational sex among females and multiple partnerships among males, while condom use is inconsistent. Efforts to promote delay in sexual initiation, partner reduction and consistent condom use should be supplemented with initiatives against harmful gender norms, child abuse and transactional sex and skills to negotiate safe sex. Standardization of survey methods to facilitate cross-study comparisons should continue and encompass additional risk factors such as transactional sex, gender-based violence, drug use and HIV treatment adherence.

Sex differences in the development of airway epithelial tolerance to naphthalene.

Exposure to air pollution has been linked to pulmonary diseases. Naphthalene (NA), an abundant polycyclic aromatic hydrocarbon in tobacco smoke and urban air, is a model toxicant for air pollution effects in the lung. Repeated exposures to NA in male mice result in tolerance, defined as the emergence of a resistant cell phenotype after prior exposure. Tolerance has not been studied in females. Females have sex differences in airway epithelial responses and in the prevalence of certain airway diseases. Male and female mice were exposed to a tolerance-inducing regimen of NA, and lungs were examined by airway level to characterize the cellular changes associated with repeated NA exposure and to assess the expression of genes and proteins involved in NA bioactivation and detoxification. The airway epithelium in treated males resembled that of controls. Females in the tolerant state were characterized by dense populations of ciliated cells in midlevel, distal, and bifurcating airways and a lower abundance of Clara cells at all airway levels. Cytotoxicity following a secondary challenge dose was also greater in females than males. Furthermore, females had decreased gene/protein expression of CYP2F2, a P-450 that metabolizes NA to a toxic epoxide, and glutamate-cysteine ligase, the rate-limiting enzyme in glutathione synthesis, than NA-tolerant males at all airway levels examined. We conclude that, while females develop tolerance, sex differences exist in the tolerant state by airway level, and females remain more susceptible than males to repeated exposures to NA.

Rapid nondestructive analysis of threading dislocations in wurtzite materials using the scanning electron microscope.

We describe the use of electron channeling contrast imaging in the scanning electron microscope to rapidly and reliably image and identify threading dislocations (TDs) in materials with the wurtzite crystal structure. In electron channeling contrast imaging, vertical TDs are revealed as spots with black-white contrast. We have developed a simple geometric procedure which exploits the differences observed in the direction of this black-white contrast for screw, edge, and mixed dislocations for two electron channeling contrast images acquired from two symmetrically equivalent crystal planes whose g vectors are at 120° to each other. Our approach allows unambiguous identification of all TDs without the need to compare results with dynamical simulations of channeling contrast.

The structure, thermal properties and phase transformations of the cubic polymorph of magnesium tetrahydroborate.

The structure of the cubic polymorph of magnesium tetrahydroborate (γ-Mg(BH(4))(2)) has been determined in space group Ia3d from a structural database of the isoelectronic compound SiO(2); this has been corroborated by DFT calculations. The structure is found to concur with that recently determined by Filinchuk et al. (Y. Filinchuk, B. Richter, T. R. Jensen, V. Dmitriev, D. Chernyshov and H. Hagemann, Angew. Chem. Int. Ed., 2011, DOI: 10.1002/anie.201100675). The phase transformations and subsequent decomposition of γ-Mg(BH(4))(2) on heating have been ascertained from variable-temperature synchrotron X-ray diffraction data combined with thermogravimetric and mass spectrometry measurements. At ~160 °C, conversion to a disordered variant of the ß-Mg(BH(4))(2) phase (denoted as ß') is observed along with a further unidentified polymorph. There is evidence of amorphous phases during decomposition but there is no direct crystallographic indication of the existence of Mg(B(12)H(12)) or other intermediate Mg-B-H compounds. MgH(2) and finally Mg are observed in the X-ray diffraction data after decomposition.

Augmented environments for minimally invasive therapy: implementation barriers from technology to practice.

Augmented environments for medical applications have been explored and developed in an effort to enhance the clinician's view of anatomy and facilitate the performance of minimally invasive procedures. These environments must faithfully represent the real surgical field and require seamless integration of pre- and intra-operative imaging, surgical instrument tracking and display technology into a common framework centered around the patient. However, few image guidance environments have been successfully translated into clinical use. Several challenges that contribute to the slow progress of integrating such environments into clinical practice are discussed here in terms of both technical and clinical limitations.

Utility of optical see-through head mounted displays in augmented reality-assisted surgery: A systematic review.

This article presents a systematic review of optical see-through head mounted display (OST-HMD) usage in augmented reality (AR) surgery applications from 2013 to 2020. Articles were categorised by: OST-HMD device, surgical speciality, surgical application context, visualisation content, experimental design and evaluation, accuracy and human factors of human-computer interaction. 91 articles fulfilled all inclusion criteria. Some clear trends emerge. The Microsoft HoloLens increasingly dominates the field, with orthopaedic surgery being the most popular application (28.6%). By far the most common surgical context is surgical guidance (n=58) and segmented preoperative models dominate visualisation (n=40). Experiments mainly involve phantoms (n=43) or system setup (n=21), with patient case studies ranking third (n=19), reflecting the comparative infancy of the field. Experiments cover issues from registration to perception with very different accuracy results. Human factors emerge as significant to OST-HMD utility. Some factors are addressed by the systems proposed, such as attention shift away from the surgical site and mental mapping of 2D images to 3D patient anatomy. Other persistent human factors remain or are caused by OST-HMD solutions, including ease of use, comfort and spatial perception issues. The significant upward trend in published articles is clear, but such devices are not yet established in the operating room and clinical studies showing benefit are lacking. A focused effort addressing technical registration and perceptual factors in the lab coupled with design that incorporates human factors considerations to solve clear clinical problems should ensure that the significant current research efforts will succeed.

SERV-CT: A disparity dataset from cone-beam CT for validation of endoscopic 3D reconstruction.

In computer vision, reference datasets from simulation and real outdoor scenes have been highly successful in promoting algorithmic development in stereo reconstruction. Endoscopic stereo reconstruction for surgical scenes gives rise to specific problems, including the lack of clear corner features, highly specular surface properties and the presence of blood and smoke. These issues present difficulties for both stereo reconstruction itself and also for standardised dataset production. Previous datasets have been produced using computed tomography (CT) or structured light reconstruction on phantom or ex vivo models. We present a stereo-endoscopic reconstruction validation dataset based on cone-beam CT (SERV-CT). Two ex vivo small porcine full torso cadavers were placed within the view of the endoscope with both the endoscope and target anatomy visible in the CT scan. Subsequent orientation of the endoscope was manually aligned to match the stereoscopic view and benchmark disparities, depths and occlusions are calculated. The requirement of a CT scan limited the number of stereo pairs to 8 from each ex vivo sample. For the second sample an RGB surface was acquired to aid alignment of smooth, featureless surfaces. Repeated manual alignments showed an RMS disparity accuracy of around 2 pixels and a depth accuracy of about 2 mm. A simplified reference dataset is provided consisting of endoscope image pairs with corresponding calibration, disparities, depths and occlusions covering the majority of the endoscopic image and a range of tissue types, including smooth specular surfaces, as well as significant variation of depth. We assessed the performance of various stereo algorithms from online available repositories. There is a significant variation between algorithms, highlighting some of the challenges of surgical endoscopic images. The SERV-CT dataset provides an easy to use stereoscopic validation for surgical applications with smooth reference disparities and depths covering the majority of the endoscopic image. This complements existing resources well and we hope will aid the development of surgical endoscopic anatomical reconstruction algorithms.