250 research outputs found
Monte Carlo simulation of a hard-sphere gas in the planar Fourier flow with a gravity field
By means of the Direct Simulation Monte Carlo method, the Boltzmann equation
is numerically solved for a gas of hard spheres enclosed between two parallel
plates kept at different temperatures and subject to the action of a gravity
field normal to the plates. The profiles of pressure, density, temperature and
heat flux are seen to be quite sensitive to the value of the gravity
acceleration . If the gravity field and the heat flux are parallel (),
the magnitudes of both the temperature gradient and the heat flux are smaller
than in the opposite case (). When considering the actual heat flux
relative to the value predicted by the Fourier law, it is seen that, if ,
the ratio increases as the reduced local field strength increases, while the
opposite happens if . The simulation results are compared with theoretical
predictions for Maxwell moleculesComment: 18 pages (LaTex), 7 figures (eps
Modélisation 3D des façades de bâtiments des anciennes Médina
Le LIDAR (Light Detecting and Ranging) terrestre statique est un outil de levé présentant actuellement une source de données 3D indispensable dans l’évaluation et la surveillance des bâtiments patrimoniaux. A travers des processus automatiques de modélisation 3D, la manipulation de cette source de données dans des outils de communication devient plus souple. Le processus de modélisation 3D impose des sous missions indispensables dont la segmentation. Une grande partie des approches de segmentation se focalisent sur l’emploi des composantes géométriques en exploitant la représentation mathématique d’une surface plane ou courbée. En raison de la complexité de l’architecture des façades, une segmentation utilisant uniquement l’aspect géométrique reste insuffisante. Ainsi, une nouvelle approche de segmentation est développée équilibrant les résultats de l’extraction des surfaces homogènes. Ceci, en se basant sur l’ensemble des composantes d’un nuage de points coloriés à savoir les composantes géométriques, les valeurs RGB et les intensités laser des détails constituant les façades des bâtiments des anciennes Médina. Le processus s’initialise par l’extraction des segments plans à l’aide de l’algorithme RANSAC. Le résultat fera l’objet d’une deuxième segmentation radiométrique basée sur l’introduction du critère de similarité couleur dans l’algorithme de croissance de région. Enfin une fusion de classes sera effectuée en fonction de la similarité de l’intensité laser.
The static terrestrial LIDAR is a tool of surveying which present a vital source of 3D data in the heritage buildings evaluation and monitoring. Through automated 3D modeling process, manipulating this data source in communication tools becomes more flexible. The 3D modeling process imposes on essential tasks including segmentation. Much of segmentation approaches focus on the use of geometric components by exploiting the mathematical representation of a plane or curved area. Due to the complexity of the facades architecture, segmentation using only the geometrical aspect is insufficient. Thus, a new segmentation approach is developed balancing the results of extracting homogeneous areas based on all colored point cloud components namely geometric data, the RGB values and intensities of facades details especially in old Medina building. The process consists of the planar segments extracting using the RANSAC algorithm. The result will be subject to radiometric segmentation through the introduction of color similarity criterion in the region growing algorithm and finally a fusion of classes based on the intensity’s similarity
A Novel Approach for Education Indoor Air Quality Management using Wireless Sensor Networks
Abstract: Learning environments are a very important component in the educational system, and have a major role in improving learners' performance. However changes in Indoor Environment Quality (IEQ) factors such as temperature, CO2 level, and noise in addition to the number of students per class can harm learners' health and decrease their knowledge acquisition capacities. Due to the number of studies that showed how IEQ improvement leads to students' performance increase, this paper present the implementation, design and results of a WSN based IEQ monitoring system for the sake of students' performance improvement and decision making accuracy increase
Verrucous carcinoma arising in an extended giant condyloma acuminatum (Buschke–Löwenstein tumor): a case report and review of the literature
INTRODUCTION: Verrucous carcinoma of the external genitalia and perianal region is a rare variant of well-differentiated squamous cell carcinoma. It has been reported to have limited metastatic potential. CASE PRESENTATION: We report the case of a 54 year-old Moroccan man who presented with locally advanced giant condyloma acuminatum (Buschke–Löwenstein tumor) after prolonged intervals of neglect (approximately 10 years). The disease covered his suprapubic, external genitalia and perianal region. It was locally aggressive with extensive tissue destruction. After a biopsy of the lesion, the diagnosis of verrucous carcinoma was confirmed. He initially received chemoradiotherapy, followed by extensive local excision, but he developed septic shock and died a few days later. CONCLUSIONS: The purpose of this case report is to present a case of verrucous carcinoma arising in an extensive giant condyloma acuminatum (Buschke–Löwenstein tumor) and discuss the literature on its diagnosis and management
Symmetries and observables in topological gravity
After a brief review of topological gravity, we present a superspace approach
to this theory. This formulation allows us to recover in a natural manner
various known results and to gain some insight into the precise relationship
between different approaches to topological gravity. Though the main focus of
our work is on the vielbein formalism, we also discuss the metric approach and
its relationship with the former formalism.Comment: 34 pages; a few explanations added in subsection 2.2.1, published
version of pape
Critical Role of the Virus-Encoded MicroRNA-155 Ortholog in the Induction of Marek's Disease Lymphomas
Notwithstanding the well-characterised roles of a number of oncogenes in neoplastic transformation, microRNAs (miRNAs) are increasingly implicated in several human cancers. Discovery of miRNAs in several oncogenic herpesviruses such as KSHV has further highlighted the potential of virus-encoded miRNAs to contribute to their oncogenic capabilities. Nevertheless, despite the identification of several possible cancer-related genes as their targets, the direct in vivo role of virus-encoded miRNAs in neoplastic diseases such as those induced by KSHV is difficult to demonstrate in the absence of suitable models. However, excellent natural disease models of rapid-onset Marek's disease (MD) lymphomas in chickens allow examination of the oncogenic potential of virus-encoded miRNAs. Using viruses modified by reverse genetics of the infectious BAC clone of the oncogenic RB-1B strain of MDV, we show that the deletion of the six-miRNA cluster 1 from the viral genome abolished the oncogenicity of the virus. This loss of oncogenicity appeared to be primarily due to the single miRNA within the cluster, miR-M4, the ortholog of cellular miR-155, since its deletion or a 2-nucleotide mutation within its seed region was sufficient to inhibit the induction of lymphomas. The definitive role of this miR-155 ortholog in oncogenicity was further confirmed by the rescue of oncogenic phenotype by revertant viruses that expressed either the miR-M4 or the cellular homolog gga-miR-155. This is the first demonstration of the direct in vivo role of a virus-encoded miRNA in inducing tumors in a natural infection model. Furthermore, the use of viruses deleted in miRNAs as effective vaccines against virulent MDV challenge, enables the prospects of generating genetically defined attenuated vaccines
The Val158Met COMT polymorphism is a modifier of the age at onset in Parkinson's disease with a sexual dimorphism
The catechol-O-methyltranferase (COMT) is one of the main enzymes that metabolise dopamine in the brain. The Val158Met polymorphism in the COMT gene (rs4680) causes a trimodal distribution of high (Val/Val), intermediate (Val/Met) and low (Met/Met) enzyme activity. We tested whether the Val158Met polymorphism is a modifier of the age at onset (AAO) in Parkinson's disease (PD). The rs4680 was genotyped in a total of 16 609 subjects from five independent cohorts of European and North American origin (5886 patients with PD and 10 723 healthy controls). The multivariate analysis for comparing PD and control groups was based on a stepwise logistic regression, with gender, age and cohort origin included in the initial model. The multivariate analysis of the AAO was a mixed linear model, with COMT genotype and gender considered as fixed effects and cohort and cohort-gender interaction as random effects. COMT genotype was coded as a quantitative variable, assuming a codominant genetic effect. The distribution of the COMT polymorphism was not significantly different in patients and controls (p=0.22). The Val allele had a significant effect on the AAO with a younger AAO in patients with the Val/Val (57.1±13.9, p=0.03) than the Val/Met (57.4±13.9) and the Met/Met genotypes (58.3±13.5). The difference was greater in men (1.9 years between Val/Val and Met/Met, p=0.007) than in women (0.2 years, p=0.81). Thus, the Val158Met COMT polymorphism is not associated with PD in the Caucasian population but acts as a modifier of the AAO in PD with a sexual dimorphism: the Val allele is associated with a younger AAO in men with idiopathic PD
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