2,441 research outputs found
Multi-scale 3-D Surface Description: Open and Closed Surfaces
A novel technique for multi-scale smoothing of a free-form 3-D surface is presented. Complete triangulated models of 3-D objects are constructed automatically and using a local parametrization technique, are then smoothed using a 2-D Gaussian filter. Our method for local parametrization makes use of semigeodesic coordinates as a natural and efficient way of sampling the local surface shape. The smoothing eliminates the surface noise together with high curvature regions such as sharp edges, therefore, sharp corners become rounded as the object is smoothed iteratively. Our technique for free-form 3-D multi-scale surface smoothing is independent of the underlying triangulation. It is also argued that the proposed technique is preferrable to volumetric smoothing or level set methods since it is applicable to incomplete surface data which occurs during occlusion. Our technique was applied to closed as well as open 3-D surfaces and the results are presented here
Multi-Scale Free-Form Surface Description and Curvature Estimation
A novel technique for multi-scale smoothing of a free-form 3-D surface is presented. Complete triangulated models of 3-D objects are constructed at our center [4] and using a local parametrization technique, are then smoothed using a 2-D Gaussian filter. Our method for local parametrization makes use of semigeodesic coordinates as a natural and efficient way of sampling the local surface shape. The smoothing eliminates the surface noise together with high curvature regions such as sharp edges, therefore, sharp corners become rounded as the object is smoothed iteratively. Our technique for free-form 3-D multi-scale surface smoothing is independent of the underlying triangulation. It is also argued that the proposed technique is preferrable to volumetric smoothing or level set methods since it is applicable to incomplete surface data which occurs during occlusion. The technique was applied to simple and complex 3-D objects and the results are presented here
Non-adiabatic corrections to elastic scattering of halo nuclei
We derive the formalism for the leading order corrections to the adiabatic
approximation to the scattering of composite projectiles. Assuming a two-body
projectile of core plus loosely-bound valence particle and a model (the core
recoil model) in which the interaction of the valence particle and the target
can be neglected, we derive the non-adiabatic correction terms both exactly,
using a partial wave analysis, and using the eikonal approximation. Along with
the expected energy dependence of the corrections, there is also a strong
dependence on the valence-to-core mass ratio and on the strength of the
imaginary potential for the core-target interaction, which relates to
absorption of the core in its scattering by the target. The strength and
diffuseness of the core-target potential also determine the size of the
corrections. The first order non-adiabatic corrections were found to be smaller
than qualitative estimates would expect. The large absorption associated with
the core-target interaction in such halo nuclei as Be11 kills off most of the
non-adiabatic corrections. We give an improved estimate for the range of
validity of the adiabatic approximation when the valence-target interaction is
neglected, which includes the effect of core absorption. Some consideration was
given to the validity of the eikonal approximation in our calculations.Comment: 14 pages with 10 figures, REVTeX4, AMS-LaTeX v2.13, submitted to
Phys. Rev.
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Visualization of uncertainty and analysis of geographical data
A team of five worked on this challenge to identify a possible criminal strucutre within the Flitter social network. Initially we worked on the problem individually, deliberately not sharing any data, results or conclusions. This maximised the chances of spotting any blunders, unjustified assumptions or inferences and allowed us to triangulate any common conclusions. After an agreed period we shared our results demonstrating the visualization applications we had built and the reasoning behind our conclusions. This sharing of assumptions encouraged us to incorporate uncertainty in our visualization approaches as it became clear that there was a number of possible interpretations of the rules and assumptions governing the challenge. This summary of the work emphasises one of those applications detailing the geographic analysis and uncertainty handling of the network data. ©2009 IEEE
Effects of an induced three-body force in the incident channel of (d,p) reactions
A widely accepted practice for treating deuteron breakup in
reactions relies on solving a three-body Schr\"odinger equation with
pairwise -, - and - interactions. However, it was shown in
[Phys. Rev. C \textbf{89}, 024605 (2014)] that projection of the many-body
wave function into the three-body channel results in a
complicated three-body operator that cannot be reduced to a sum of pairwise
potentials. It contains explicit contributions from terms that include
interactions between the neutron and proton via excitation of the target .
Such terms are normally neglected. We estimate the first order contribution of
these induced three-body terms and show that applying the adiabatic
approximation to solving the model results in a simple modification of
the two-body nucleon optical potentials. We illustrate the role of these terms
for the case of Ca()Ca transfer reactions at incident
deuteron energies of 11.8, 20 and 56 MeV, using several parameterisations of
nonlocal optical potentials.Comment: 7 pages, 2 figures. Publication due in Phys. Rev.
Evaluating the miR-302b and miR-145 expression in formalin-fixed paraffin-embedded samples of esophageal squamous cell carcinoma
Background: MicroRNAs are involved in key cellular processes regulating, and their misregulation is linked to cancer. The miR-302-367 cluster is exclusively expressed in embryonic stem and carcinoma cells. This cluster also promotes cell reprogramming and stemness process. In contrast, miR-145 is mostly regarded as a tumor suppressor, where it regulates cellular functions such as cell division, differentiation, and apoptosis. By suppressing the main pluripotency factors (OCT4, SOX2, MYC and KLF4), miR-145 silences the self-renewal program in ESCs. Therefore, the main aim of this study is to find a potential link between the expression level of hsa-miR-302b and hsa-miR-145 with tumor vs. non-tumor as well as high-grade vs. low-grade states of the esophageal tissue samples. Methods: A total number of 40 formalin-fixed, paraffin-embedded (FFPE) samples of esophageal squamous-cell carcinoma (ESCC) were obtained, and the tumor and marginal non-tumor areas delineated and punched off by an expert pathologist. Total RNA was extracted with Trizol, and cDNA synthesized using the miRCURY LNA™ Universal RT microRNA PCR Kit. Real-time reverse transcription polymerase chain reaction (RT-PCR) assays were performed using specific LNA-primers and SYBR Green master mix. Results: The expression level of miR-302b failed to show any significant difference, neither between tumor and their non-tumor counterparts, nor among tumors with different grades of malignancies (P > 0.05). In contrast, miR-145 was significantly down regulated in all grades of tumor samples (P 0.05). CONCLUSION: Our data revealed a significant down-regulation of miR-145 in ESCC tissue samples. Based on our ROC curve analysis data (AUC = 0.74, P < 0.001) miR-145 could be regarded as a potential tumor marker for diagnosis of esophageal cancer. © 2015, Academy of Medical Sciences of I.R. Iran. All rights reserved
Structure and arrangement of photoreceptors in the retina of big eye kilka, Clupeonella grimmi (Kessler 1877)
The big eye kilka, Clupeonella grimmi, is a marine fish living in depth of 20 to 200 meter of the Caspian Sea. Its eye and retina were processed for histological and SEM studies. Paraffin embedded retina was cut radially and tangentially in 5 µm thickness and stained with hematoxylin and eosin method. The unstained sections were manipulated for SEM image observations. Tangential retinal sections showed irregular arrangement of cones. Five morphologically different types of photoreceptors were distinguished as rods, short single cones, long single cones, twin cones and double cones. The cones were counted in each quadrant of the retina and cone density was determined. The cones showed increment in diameter but reduction in number at anti-clockwise direction without any specific arrangement. Presence of four types of cone cells and their pattern of distribution revealed assistance in near surface color vision and more light capture in dim light of deeper waters as an adaptation to planktivorous feeding habit and deep water living habitat
Iran's activities on prevention, treatment and harm reduction of drug abuse
Context: In the present review study, authors investigated Iran's activities regarding prevention, abuse and harm reduction of drugs nationwide. The issue appears to be important in order to show the trend of activities in the country. Evidence Acquisition: In this report, authors gathered data from different Farsi/English peer review journals issued both in printed and online versions. These journals have been indexed in PubMed, ISI, ISC, SID, Magiran, UN, etc. These are among the most referred and cited databases. Results: Summarizing the data led to three distinguished sections: 1) drug supply reduction activities; 2) drug demand reduction activities; 3) harm reduction activities. Conclusions: As the results showed, the trend of activities was encouraging and some additional activities could be included to future programs relying on early-onset preventions. © 2015, Zahedan University of Medical Sciences
The significance of local thermal non-equilibrium in simulations of enhanced geothermal recovery
International audienceAccessing the thermo-mechanical response of large deep hot dry rock (HDR) reservoirs during geothermal extraction remains a challenging task that can be comprehended with numerical tools. Of crucial im-portance to the economic viability of these HDR reservoirs is the knowledge of thermal output evolution, fluid excessive pressure and induced thermal stress, at various steps of the circulation tests. Thermal recovery from a HDR reservoir, viewed as a deformable fractured medium, is investigated with a focus on the assumption of lo-cal thermal non-equilibrium (LTNE). To this end, a fully coupled finite element formulation for a thermo-elastic fractured medium in LTNE is developed (Gelet et al. 2013). Hydraulic diffusion, thermal diffusion, forced con-vection and deformation are considered in a two-phase framework, the solid phase being made by impermeable solid blocks separated by saturated fractures. Each of the two phases is endowed with its own temperature. The resulting system of equations is used to address a generic HDR reservoir subjected to temperature and pressure gradients. A change of time profile of the outlet fluid temperature is observed as the fracture spacing increases, switching from a single-step pattern to a double-step pattern, a feature which is viewed as characteristic of established LTNE. A dimensionless number is proposed to delineate between local thermal equilibrium (LTE) and non-equilibrium. This number embodies local physical properties of the mixture, elements of the geometry of the reservoir and the production flow rate. All the above properties being fixed, the resulting fracture spacing threshold between LTNE and LTE is found to decrease with increasing porosity. The thermally induced effec-tive stress is tensile near the injection well, illustrating the thermal contraction of the rock, while the pressure contribution of the fracture fluid is negligible during the late period
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