Autocalibration with the Minimum Number of Cameras with Known Pixel Shape

In 3D reconstruction, the recovery of the calibration parameters of the cameras is paramount since it provides metric information about the observed scene, e.g., measures of angles and ratios of distances. Autocalibration enables the estimation of the camera parameters without using a calibration device, but by enforcing simple constraints on the camera parameters. In the absence of information about the internal camera parameters such as the focal length and the principal point, the knowledge of the camera pixel shape is usually the only available constraint. Given a projective reconstruction of a rigid scene, we address the problem of the autocalibration of a minimal set of cameras with known pixel shape and otherwise arbitrarily varying intrinsic and extrinsic parameters. We propose an algorithm that only requires 5 cameras (the theoretical minimum), thus halving the number of cameras required by previous algorithms based on the same constraint. To this purpose, we introduce as our basic geometric tool the six-line conic variety (SLCV), consisting in the set of planes intersecting six given lines of 3D space in points of a conic. We show that the set of solutions of the Euclidean upgrading problem for three cameras with known pixel shape can be parameterized in a computationally efficient way. This parameterization is then used to solve autocalibration from five or more cameras, reducing the three-dimensional search space to a two-dimensional one. We provide experiments with real images showing the good performance of the technique.Comment: 19 pages, 14 figures, 7 tables, J. Math. Imaging Vi

Using salinity to improve nutritional and market value of strawberries

Plants respond to salinity by producing antioxidants and osmolytes; some of these are nutritionally useful to humans (e.g. phenolics), or may improve the sensory quality of produce (e.g. sugars). For the current study, strawberries were irrigated with 0, 10, 20 or 40 mM NaCl, and the responses in antioxidants, phenolics, and flavour attributes were measured. A linear positive relationship was observed between salt stress and antioxidant concentrations, and the DPPH antioxidant assay responded more clearly than the FRAP assay. Phenolics were increased with statistical significance by salinity at all treatment levels, although trends differed between total phenolics and the subclasses anthocyanins and total flavonoids. It was seen that mild salinity (10 mM) with a low impact on yield could be used to increase antioxidants (6-10% above control) and total phenolics (11-16% above control). However differences between cultivars outweighed differences due to salinity in treatments below 20 mM NaCl. We found that sugars in strawberries (unlike other fruits) weren’t increased by salinity treatment. The lack of sugar increase can be explained by suggesting that organic acids are more important osmolytes than sugars for strawberries under salinity. However it was also determined that the failure of strawberries to increase their soluble sugars during salt stress can be explained by the lean nutrient regimes used by researchers, which don’t represent commercial production practices. Practically, mild salinity (≤20 mM) can be used to increase strawberry fruit value, but should be combined with an appropriate nutrient regime to avoid harm to flavour quality. The varieties Elsanta and Elsinore are both suitable for salt treatment, but Elsanta is better for antioxidant and phenolic production, as well as being more salt tolerant

Covariant scalar representation of iosp(d,2/2)iosp(d,2/2) quantization of the scalar relativistic particle

A covariant scalar representation of $iosp(d,2/2)$ is constructed and analysed in comparison with existing methods for the quantization of the scalar relativistic particle. It is found that, with appropriately defined wavefunctions, this $iosp(d,2/2)$ produced representation can be identified with the state space arising from the canonical BFV-BRST quantization of the modular invariant, unoriented scalar particle (or antiparticle) with admissible gauge fixing conditions. For this model, the cohomological determination of physical states can thus be obtained purely from the representation theory of the $iosp(d,2/2)$ algebra.Comment: 16 pages Late

Three manifestations of the pulsed harmonic potential

We consider, in turn, three systems being acted upon by a regularly pulsed harmonic potential (PHP). These are i) a classical particle, ii) a quantum particle, and iii) a directed line. We contrast the mechanics of the first two systems by parameterizing their bands of stability and periodicity. Interesting differences due to quantum fluctuations are examined in detail. The fluctuations of the directed line are calculated in the two cases of a binding PHP, and an unbinding PHP. In the latter case there is a finite maximum line length for a given potential strength.Comment: 34 Revtex pages, with 5 attached figure

Anti-oxidized LDL antibodies and coronary artery disease: a systematic review

Antibodies to oxidized LDL (oxLDL) may be associated with improved outcomes in cardiovascular disease. However, analysis is restricted by heterogenous study design and endpoints. Our objective was to conduct a comprehensive systematic review assessing anti-oxLDL antibodies in relation to coronary artery disease (CAD). Through a systematic literature search, we identified all studies assessing the relationship of either, IgG or IgM ox-LDL/ copper-oxLDL/ malondialdehyde-LDL, with coronary atherosclerosis or cardiovascular events in populations with, and without, established CAD. Systematic review best practices were adhered to and study quality was assessed. An initial electronic database search identified 2059 records, which was subsequently followed by abstract and full-text review. Finally, we included 18 studies with over 1811 patients with CAD. The studies varied according to populations studied, conventional cardiovascular risk factors and interventional modalities used to assess CAD. IgM anti-oxLDL antibodies were found to indicate protection from more severe CAD and possibly cardiovascular events, whilst the relationship with IgG is more complex and difficult to elucidate, with studies reporting divergent results. In this systematic review, there is evidence that suggests a relationship between anti-oxLDL antibodies and CAD, especially for the IgM subclass. However, further studies, with well-characterized prospective cohorts, will be important to clarify these associations

Resonance line-profile calculations based on hydrodynamical models of cataclysmic variable winds

We present synthetic line profiles as predicted by the models of 2-D line- driven disk winds due to Proga, Stone & Drew. We compare the model line profiles with HST observations of the cataclysmic variable IX Vel. The model wind consists of a slow outflow that is bounded on the polar side by a fast stream. We find that these two components of the wind produce distinct spectral features. The fast stream produces profiles which show features consistent with observations. These include the appearance of the P-Cygni shape for a range of inclinations, the location of the maximum depth of the absorption component at velocities less than the terminal velocity, and the transition from absorption to emission with increasing inclination. However the model profiles have too little absorption or emission equivalent width. This quantitative difference between our models and observations is not a surprise because the line-driven wind models predict a mass loss rate that is lower than the rate required by the observations. We note that the model profiles exhibit a double-humped structure near the line center which is not echoed in observations. We identify this structure with a non-negligible redshifted absorption which is formed in the slow component of the wind where the rotational velocity dominates over expansion velocity. We conclude that the next generation of disk wind models, developed for application to CVs, needs to yield stronger wind driving out to larger disk radii than do the present models.Comment: LaTeX, 19 pages, to appear in Ap

Activity of the DNA minor groove cross-linking agent SG2000 (SJG-136) against canine tumours

BACKGROUND: Cancer is the leading cause of death in older dogs and its prevalence is increasing. There is clearly a need to develop more effective anti-cancer drugs in dogs. SG2000 (SJG-136) is a sequence selective DNA minor groove cross-linking agent. Based on its in vitro potency, the spectrum of in vivo and clinical activity against human tumours, and its tolerability in human patients, SG2000 has potential as a novel therapeutic against spontaneously occurring canine malignancies. RESULTS: In vitro cytotoxicity was assessed using SRB and MTT assays, and in vivo activity was assessed using canine tumour xenografts. DNA interstrand cross-linking (ICL) was determined using a modification of the single cell gel electrophoresis (comet) assay. Effects on cell cycle distribution were assessed by flow cytometry and measurement of γ-H2AX by immunofluorescence and immunohistochemistry. SG2000 had a multi-log differential cytotoxic profile against a panel of 12 canine tumour cell lines representing a range of common tumour types in dogs. In the CMeC-1 melanoma cell line, DNA ICLs increased linearly with dose following a 1 h treatment. Peak ICL was achieved within 1 h and no removal was observed over 48 h. A relationship between DNA ICL formation and cytotoxicity was observed across cell lines. The formation of γ-H2AX foci was slow, becoming evident after 4 h and reaching a peak at 24 h. SG2000 exhibited significant anti-tumour activity against two canine melanoma tumour models in vivo. Anti-tumour activity was observed at 0.15 and 0.3 mg/kg given i.v. either once, or weekly x 3. Dose-dependent DNA ICL was observed in tumours (and to a lower level in peripheral blood mononuclear cells) at 2 h and persisted at 24 h. ICL increased following the second and third doses in a repeated dose schedule. At 24 h, dose dependent γ-H2AX foci were more numerous than at 2 h, and greater in tumours than in peripheral blood mononuclear cells. SG2000-induced H2AX phosphorylation measured by immunohistochemistry showed good correspondence, but less sensitivity, than measurement of foci. CONCLUSIONS: SG2000 displayed potent activity in vitro against canine cancer cell lines as a result of the formation and persistence of DNA ICLs. SG2000 also had significant in vivo antitumour activity against canine melanoma xenografts, and the comet and γ-H2AX foci methods were relevant pharmacodynamic assays. The clinical testing of SG2000 against spontaneous canine cancer is warranted. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12917-015-0534-2) contains supplementary material, which is available to authorized users

An efficient platform for astrocyte differentiation from human induced pluripotent stem cells

Summary: Growing evidence implicates the importance of glia, particularly astrocytes, in neurological and psychiatric diseases. Here, we describe a rapid and robust method for the differentiation of highly pure populations of replicative astrocytes from human induced pluripotent stem cells (hiPSCs), via a neural progenitor cell (NPC) intermediate. We evaluated this protocol across 42 NPC lines (derived from 30 individuals). Transcriptomic analysis demonstrated that hiPSC-astrocytes from four individuals are highly similar to primary human fetal astrocytes and characteristic of a non-reactive state. hiPSC-astrocytes respond to inflammatory stimulants, display phagocytic capacity, and enhance microglial phagocytosis. hiPSC-astrocytes also possess spontaneous calcium transient activity. Our protocol is a reproducible, straightforward (single medium), and rapid (<30 days) method to generate populations of hiPSC-astrocytes that can be used for neuron-astrocyte and microglia-astrocyte co-cultures for the study of neuropsychiatric disorders. : Brennand, Goate, and colleagues report a rapid and robust method for the differentiation of highly pure populations of replicative astrocytes from human induced pluripotent stem cells (hiPSCs) via a neural progenitor cell (NPC) intermediate. hiPSC-astrocytes resemble primary human fetal astrocytes, have a transcriptional signature consistent with a non-reactive state, respond to inflammatory stimulants, and enhance microglial phagocytosis. Keywords: human induced pluripotent stem cell, iPSC, astrocyt

Assessing the impact of peat erosion on growing season CO2 fluxes by comparing erosional peat pans and surrounding vegetated haggs (article)

This is the author accepted manuscript. The final version is available from International Mire Conservation Group and International Peat Society via the DOI in this record.The research data supporting this publication are openly available from the University of Exeter's institutional repository at: https://doi.org/10.24378/exe.1143.Peatlands are recognised as an important but vulnerable ecological resource. Understanding the effects of existing damage, in this case erosion, enables more informed land management decisions to be made. Over the growing seasons of 2013 and 2014 photosynthesis and ecosystem respiration were measured using closed chamber techniques within vegetated haggs and erosional peat pans in Dartmoor National Park, southwest England. Below-ground total and heterotrophic respiration were measured and autotrophic respiration estimated from the vegetated haggs. The mean water table was significantly higher in the peat pans than in the vegetated haggs; because of this, and the switching from submerged to dry peat, there were differences in vegetation composition, photosynthesis and ecosystem respiration. In the peat pans photosynthetic CO2 uptake and ecosystem respiration were greater than in the vegetated haggs and strongly dependent on the depth to water table (r2>0.78, p<0.001). Whilst in the vegetated haggs, photosynthesis and ecosystem respiration had the strongest relationships with normalised difference vegetation index (NDVI) (r2=0.82, p<0.001) and soil temperature at 15 cm depth (r2=0.77, p=0.001). Autotrophic and total below-ground respiration in the vegetated haggs varied with soil temperature; heterotrophic respiration increased as water tables fell. An empirically derived net ecosystem model estimated that over the two growing seasons both the vegetated haggs (29 and 20 gC m 2; 95 % confidence intervals of -570 to 762 and -873 to 1105 gC m-2) and the peat pans (7 and 8 gC m 2; 95 % confidence intervals of -147 to 465 and -136 to 436 gC m 2) were most likely net CO2 sources. This study suggests that not only the visibly degraded bare peat pans but also the surrounding vegetated haggs are losing carbon to the atmosphere, particularly during warmer and drier conditions, highlighting a need for ecohydrological restoration.MomentaSouth West Water (SWW)Dartmoor National Park Authorit

Historical Criminology and the Explanatory Power of the Past

To what extent can the past ‘explain’ the present? This deceptively simple question lies at the heart of historical criminology (research which incorporates historical primary sources while addressing present-day debates and practices in the criminal justice field). This article seeks first to categorise the ways in which criminologists have used historical data thus far, arguing that it is most commonly deployed to ‘problematize’ the contemporary rather than to ‘explain’ it. The article then interrogates the reticence of criminologists to attribute explicative power in relation to the present to historical data. Finally, it proposes the adoption of long time-frame historical research methods, outlining three advantages which would accrue from this: the identification and analysis of historical continuities; a more nuanced, shared understanding of micro/macro change over time in relation to criminal justice; and a method for identifying and analysing instances of historical recurrence, particularly in perceptions and discourses around crime and justice