8,823 research outputs found
Edge Extraction Based on Aperture Synthesis in Optical Scanning Holography
Poster Session (DW2A): no. DW2A.6We present an edge extraction method based on aperture synthesis with different pupils in optical scanning holography. By utilizing two sub-holograms covering different spatial frequency ranges of the object, sharp edges can be extracted successfully. © 2015 OSApostprin
A total variation regularization based super-resolution reconstruction algorithm for digital video
Super-resolution (SR) reconstruction technique is capable of producing a high-resolution image from a sequence of low-resolution images. In this paper, we study an efficient SR algorithm for digital video. To effectively deal with the intractable problems in SR video reconstruction, such as inevitable motion estimation errors, noise, blurring, missing regions, and compression artifacts, the total variation (TV) regularization is employed in the reconstruction model. We use the fixed-point iteration method and preconditioning techniques to efficiently solve the associated nonlinear Euler-Lagrange equations of the corresponding variational problem in SR. The proposed algorithm has been tested in several cases of motion and degradation. It is also compared with the Laplacian regularization-based SR algorithm and other TV-based SR algorithms. Experimental results are presented to illustrate the effectiveness of the proposed algorithm.ÂŁ.published_or_final_versio
A Upf3b-mutant mouse model with behavioral and neurogenesis defects.
Nonsense-mediated RNA decay (NMD) is a highly conserved and selective RNA degradation pathway that acts on RNAs terminating their reading frames in specific contexts. NMD is regulated in a tissue-specific and developmentally controlled manner, raising the possibility that it influences developmental events. Indeed, loss or depletion of NMD factors have been shown to disrupt developmental events in organisms spanning the phylogenetic scale. In humans, mutations in the NMD factor gene, UPF3B, cause intellectual disability (ID) and are strongly associated with autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD) and schizophrenia (SCZ). Here, we report the generation and characterization of mice harboring a null Upf3b allele. These Upf3b-null mice exhibit deficits in fear-conditioned learning, but not spatial learning. Upf3b-null mice also have a profound defect in prepulse inhibition (PPI), a measure of sensorimotor gating commonly deficient in individuals with SCZ and other brain disorders. Consistent with both their PPI and learning defects, cortical pyramidal neurons from Upf3b-null mice display deficient dendritic spine maturation in vivo. In addition, neural stem cells from Upf3b-null mice have impaired ability to undergo differentiation and require prolonged culture to give rise to functional neurons with electrical activity. RNA sequencing (RNAseq) analysis of the frontal cortex identified UPF3B-regulated RNAs, including direct NMD target transcripts encoding proteins with known functions in neural differentiation, maturation and disease. We suggest Upf3b-null mice serve as a novel model system to decipher cellular and molecular defects underlying ID and neurodevelopmental disorders
Studying the Structural Behaviour of RC Beams with Circular Openings of Different Sizes and Locations Using FE Method
This paper aims to investigate the structural behaviour of RC beams with circular openings of different sizes and locations modelled using ABAQUS FEM software. Seven RC beams with the dimensions of 1200 mmĂ—150 mmĂ—150 mm were tested under threepoint loading. Group A consists of three RC beams incorporating circular openings with diameters of 40 mm, 55 mm and 65 mm in the shear zone. However, Group B consists of three RC beams incorporating circular openings with diameters of 40 mm, 55 mm and 65 mm in the flexural zone. The final RC beam did not have any openings, to provide a control beam for comparison. The results show that increasing the diameter of the openings increases the maximum deflection and the ultimate failure load decreases relative to the control beam. In the shear zone, the presence of the openings caused an increase in the maximum deflection ranging between 4% and 22% and a decrease in the ultimate failure load of between 26% and 36% compared to the control beam. However, the presence of the openings in the flexural zone caused an increase in the maximum deflection of between 1.5% and 19.7% and a decrease in the ultimate failure load of between 6% and 13% relative to the control beam. In this study, the optimum location for placing circular openings was found to be in the flexural zone of the beam with a diameter of less than 30% of the depth of the beam
Impact des pesticides agricoles sur les performances physiologiques des poissons : cas du tihan 175 o-teq sur la reproduction des femelles de Clarias gariepinus exposees a des doses chroniques
L’objectif général de cette étude est de déterminer l’effet du TIHAN 175 O-TEQ sur les paramètres physiologiques de reproduction des géniteurs de C. gariepinus exposés à des doses chroniques. Cette expérimentation s’inscrit dans le cadre d’une étude écotoxicologique réalisée dans le but de mieux connaitre l’effet des pesticides sur la biodiversité aquatique. En effet, des géniteurs femelles de C. gariepinus de poids moyen 350,22 ± 86,44 g et de longueur totale moyenne 34,15 ± 4,3 cm ont été exposées au TIHAN à des doses chroniques de 1 et 10 μL de TIHAN /L d’eau pendant 45 jours. Au terme de cette durée d’exposition, les performances zootechniques de reproduction des poissons ont été évaluées au moyen de paramètres tels que le taux de fécondité, le taux de fécondation, le taux d’éclosion des oeufs et le diamètre des ovules. De même, des paramètres hématologiques (taux d’hémoglobine et hématocrite) et plasmatiques (Na+, K+, P, Cl-, Fe2+ et les protides sanguins) ont été dosés sur des prélèvements sanguins de sujet exposés ou non au TIHAN. Les résultats hémato-physiologiques obtenus au cours des analyses ont pour la plupart varié très significativement d’un traitement à l’autre. Le taux d’hémoglobine sanguin et d’hématocrite des femelles a tendance à diminuer (significativement dans le cas de l’hémoglobine) avec l’augmentation de la dose d’exposition. La concentration des éléments plasmatiques tels que le Na+ et le Fe2+ a significativement augmenté chez les poissons exposés (notamment avec la dose la plus forte), tandis que la concentration du plasma en K+, en Cl- et en P a significativement baissé au fur et à mesure que la dose d’exposition augmente (entre T0, T1 et T2). Bien que les variations observées au niveau des protides plasmatiques ne soient pas significatives (p > 0,05), on note cependant une tendance remarquable d’augmentation de la concentration des protides dans le plasma des poissons exposés au TIHAN, comparativement au témoin. Par contre, on n’a pas observé d’effets significatifs des doses expérimentées sur la majorité des paramètres zootechniques de reproduction mesurés. Seul le diamètre des ovules a significativement varié (p < 0,05) d’un traitement à l’autre (1,04 mm, 1,07 mm et 1,07 mm, respectivement avec T0, T1 et T2) après la durée d’exposition.Mots clés : Pesticides agricoles, paramètres hémato-physiologiques, reproduction des poissons, Clarias gariepinus.IMPACT OF AGRICULTURAL PESTICIDES ON THE PHYSIOLOGICAL PERFORMANCE OF FISH: THE CASE OF TIHAN 175 O-TEQ ON THE FEMALE REPRODUCTION OF Clarias gariepinus EXPOSED TO CHRONIC DOSESThe main objective of this study was to determine the effect of TIHAN 175 O-TEQ on reproductive performance of broodstock C. gariepinus exposed to chronic doses. This experiment is part of an ecotoxicological study carried out in order to assess the effect of pesticides on aquatic biodiversity. For this purpose, the females Agronomie Africaine 26 (3) : 247 - 259 (2014) 248 I. Imorou Toko et al. of C. gariepinus (mean weight = 350.22 ± 86.44 g ; and mean total length 34.15 ± 4.3  m) were exposed, in experimental condition, to doses of 1 μg/L and 10 μg/L during 45 days. After each exposure time, the reproductive performances of the experimental fish were assessed by measuring parameters such as fecundity rate, fecundation rate, hatching rate, and ovum diameter. After 45 days of exposure, the blood (heamoglobin and heamatocrit) and plasma elements (Na+, K+, P, Cl-, Fe2+ and protein) were analyzed from blood samples collected in experimental fish. Most of the reproduction parameters did not vary significantly (p > .05) according to the doses tested. However, after 45 days of exposition, the ovum diameter varies significantly (p < 0.05) according to the treatment (1.04 mm, 1.07 mm and 1.07 mm, respectively with T0, T1 and T2). In the blood as well as in the plasma, most of the parameters measured have significantly varied according to the treatments. The heamoglogin concentration and the heamatocrit decreased in fishes exposed to TIHAN, comparatively to the control. In the plasma, the elements such as Na+ and the Fe2+ have significantly increased (p < 0.05) in fish exposed to TIHAN (T2 group) than the control group (T0). On the other hand, K+, Cl- and P concentrations in fish exposed to TIHAN have decreased significantly. Although the proteins tend to increase in the plasma of fish exposed to TIHAN, no significant differences (p > 0.05) were observed among treatments.Keywords : Agricultural pesticides, blood and plasma parameters, Fish reproduction, Clarias gariepinu
Slow uniform electrical activation during sinus rhythm is an indicator of reentrant VT isthmus location and orientation in an experimental model of myocardial infarction.
BACKGROUND: To validate the predictability of reentrant circuit isthmus locations without ventricular tachycardia (VT) induction during high-definition mapping, we used computer methods to analyse sinus rhythm activation in experiments where isthmus location was subsequently verified by mapping reentrant VT circuits. METHOD: In 21 experiments using a canine postinfarction model, bipolar electrograms were obtained from 196-312 recordings with 4mm spacing in the epicardial border zone during sinus rhythm and during VT. From computerized electrical activation maps of the reentrant circuit, areas of conduction block were determined and the isthmus was localized. A linear regression was computed at three different locations about the reentry isthmus using sinus rhythm electrogram activation data. From the regression analysis, the uniformity, a measure of the constancy at which the wavefront propagates, and the activation gradient, a measure that may approximate wavefront speed, were computed. The purpose was to test the hypothesis that the isthmus locates in a region of slow uniform activation bounded by areas of electrical discontinuity. RESULTS: Based on the regression parameters, sinus rhythm activation along the isthmus near its exit proceeded uniformly (mean r2= 0.95±0.05) and with a low magnitude gradient (mean 0.37±0.10mm/ms). Perpendicular to the isthmus long-axis across its boundaries, the activation wavefront propagated much less uniformly (mean r2= 0.76±0.24) although of similar gradient (mean 0.38±0.23mm/ms). In the opposite direction from the exit, at the isthmus entrance, there was also less uniformity (mean r2= 0.80±0.22) but a larger magnitude gradient (mean 0.50±0.25mm/ms). A theoretical ablation line drawn perpendicular to the last sinus rhythm activation site along the isthmus long-axis was predicted to prevent VT reinduction. Anatomical conduction block occurred in 7/21 experiments, but comprised only small portions of the isthmus lateral boundaries; thus detection of sinus rhythm conduction block alone was insufficient to entirely define the VT isthmus. CONCLUSIONS: Uniform activation with a low magnitude gradient during sinus rhythm is present at the VT isthmus exit location but there is less uniformity across the isthmus lateral boundaries and at isthmus entrance locations. These factors may be useful to verify any proposed VT isthmus location, reducing the need for VT induction to ablate the isthmus. Measured computerized values similar to those determined herein could therefore be assistive to sharpen specificity when applying sinus rhythm mapping to localize EP catheter ablation sites
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Model study of tropospheric trace species distributions during PEM-West A
A three-dimensional mesoscale transport/photochemical model is used to study the transport and photochemical transformation of trace species over eastern Asia and western Pacific for the period from September 20 to October 6, 1991, of the Pacific Exploratory Mission-West A experiment. The influence of emissions from the continental boundary layer that was evident in the observed trace species distributions in the lower troposphere over the ocean is well simulated by the model. In the upper troposphere, species such as O3, NOy (total reactive nitrogen species), and SO2 which have a significant source in the stratosphere are also simulated well in the model, suggesting that the upper tropospheric abundances of these species are strongly influenced by stratospheric fluxes and upper tropospheric sources. In the case of SO2 the stratospheric flux is identified to be mostly from the Mount Pinatubo eruption. Concentrations in the upper troposphere for species such as CO and hydrocarbons, which are emitted in the continental boundary layer and have a sink in the troposphere, are significantly underestimated by the model. Two factors have been identified to contribute significantly to the underestimate: one is emissions upwind of the model domain (eastern Asia and western Pacific); the other is that vertical transport is underestimated in the model. Model results are also grouped by back trajectories to study the contrast between compositions of marine and continental air masses. The model-calculated altitude profiles of trace species in continental and marine air masses are found to be qualitatively consistent with observations. However, the difference in the median values of trace species between continental air and marine air is about twice as large for the observed values as for model results. This suggests that the model underestimates the outflow fluxes of trace species from the Asian continent and the Pacific rim countries to the ocean. Observed altitude profiles for species like CO and hydrocarbons show a negative gradient in continental air and a positive gradient in marine air. A mechanism which may be responsible for the altitude gradients is proposed
Seismo-acoustic ray model benchmarking against experimental tank data
Acoustic predictions of the recently developed TRACEO ray model, which accounts for bottom shear properties, are benchmarked against tank experimental data from the EPEE-1 and EPEE-2 (Elastic Parabolic Equation Experiment) experiments. Both experiments are representative of signal propagation in a Pekeris-like shallow-water waveguide over a non-flat isotropic elastic bottom, where significant interaction of the signal with the bottom can be expected. The benchmarks show, in particular, that the ray model can be as accurate as a parabolic approximation model benchmarked in similar conditions. The results of benchmarking are important, on one side, as a preliminary experimental validation of the model and, on the other side, demonstrates the reliability of the ray approach for seismo-acoustic applications. (C) 2012 Acoustical Society of America. [http://dx.doi.org/10.1121/1.4734236
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