QoS Issues in MANET: A Comparative Study over Different Routing Protocols

MANETs are composed of autonomous nodes that are self-managed without any existing of infrastructure and centralized administration. Therefore, each node operates not only as an end system but also as a router to forward packets for other nodes. For these reasons, the network has a dynamic topology, so nodes can easily join or leave the network at any time. Routing information differentiates these networks from other ad-hoc networks. The study of QoS issues in Mobile Ad-hoc Network is done by simulation in MATLAB that can help in better understanding of the behavior of various routing protocols. This paper is intended to compare QoS parameters of various routing protocols

Numerical solution of singularly perturbed 2-D convection-diffusion elliptic interface PDEs with Robin-type boundary conditions

We consider a singularly perturbed two-dimensional convection-diffusion elliptic interface problem with Robin boundary conditions, where the source term is a discontinuous function. The coefficient of the highest-order terms in the differential equation and in the boundary conditions, denoted by ε, is a positive parameter which can be arbitrarily small. Due to the discontinuity in the source term and the presence of the diffusion parameter, the solutions to such problems have, in general, boundary, corner and weak-interior layers. In this work, a numerical approach is carried out using a finite-difference technique defined on an appropriated layer-adapted piecewise uniform Shishkin mesh to provide a good estimate of the error. We show some numerical results which corroborate in practice that these results are sharp

A numerical approach for a two-parameter singularly perturbed weakly-coupled system of 2-D elliptic convection–reaction–diffusion PDEs

In this work, we consider the numerical approximation of a two dimensional elliptic singularly perturbed weakly-coupled system of convection–reaction–diffusion type, which has two different parameters affecting the diffusion and the convection terms, respectively. The solution of such problems has, in general, exponential boundary layers as well as corner layers. To solve the continuous problem, we construct a numerical method which uses a finite difference scheme defined on an appropriate layer-adapted Bakhvalov–Shishkin mesh. Then, the numerical scheme is a first order uniformly convergent method with respect both convection and diffusion parameters. Numerical results obtained with the algorithm for some test problems are presented, which show the best performance of the proposed method, and they also corroborate in practice the theoretical analysis

A Comparative Pharmacognostical Study of Wild and Cultivate Amalaki (Emblica officinalis Gaertn.)

Background: Amalaki is traditionally used drug in Ayurveda. Fruits of Amalaki is useful for cure of many disorders. On the basis of Desha Bheda (Habitat) two types of Amalaki are available viz., Gramya Phala (Cultivated) and Vanya Phala (Wild). cultivated variety is more often used as it offers gain to the manufacturers in terms of the amount of pulp available. To differentiate wild and cultivated variety through macroscopic, microscopic and powder microscopy this study was carried out. Objective: Present study was aimed to record comparative macroscopic, microscopic and powder microscopy of wild and cultivated varieties of Indian gooseberry. Methods: Authenticated matured fruits of both varieties were collected and macroscopic and microscopic characters were documented. Result: Fruit of wild variety is smaller and strong astringent than cultivated. In transverse section wild variety shows thick cuticle, lesser engaged area of mesocarp, compactly arranged cells and more concentration of fibres, sclereids and silica crystals than cultivated. Conclusion: Fruit of both varieties differ in size, colour and taste. In transverse section both varieties have same cells with some differentiating characters

Numerical Treatment of a Two-Parameter Singularly Perturbed Elliptic Problem with Discontinuous Convection and Source Terms.

[EN]In this paper, we address a two-parameter singularly perturbed convection-reaction-diffusion 2-D problem. We also consider that the convection and source terms are discontinuous in space. Due to these discontinuities and the presence of perturbation parameters, solutions to such problems show boundary and interior layers. In this study, we have carried out a numerical approach using a finite-difference technique with an appropriate layer-adapted piecewise uniform Shishkin mesh. Some examples are presented which show the best performance of the proposed method and its agreement with the theoretical analysis

Role of slip and twinning on the forming behaviour of AZ31 magnesium sheet in bending and roll forming

This study answered how magnesium sheet alloy behave during bending and roll forming process. It highlighted the springback and slip and twinning behavior. The finding pointed to support roll formability of magnesium alloys in the automotive industry.<br /

Host and parasite genetics shape a link between Trypanosoma cruzi infection dynamics and chronic cardiomyopathy.

Host and parasite diversity are suspected to be key factors in Chagas disease pathogenesis. Experimental investigation of underlying mechanisms is hampered by a lack of tools to detect scarce, pleiotropic infection foci. We developed sensitive imaging models to track Trypanosoma cruzi infection dynamics and quantify tissue-specific parasite loads, with minimal sampling bias. We used this technology to investigate cardiomyopathy caused by highly divergent parasite strains in BALB/c, C3H/HeN and C57BL/6 mice. The gastrointestinal tract was unexpectedly found to be the primary site of chronic infection in all models. Immunosuppression induced expansion of parasite loads in the gut and was followed by widespread dissemination. These data indicate that differential immune control of T. cruzi occurs between tissues and shows that the large intestine and stomach provide permissive niches for active infection. The end-point frequency of heart-specific infections ranged from 0% in TcVI-CLBR-infected C57BL/6 to 88% in TcI-JR-infected C3H/HeN mice. Nevertheless, infection led to fibrotic cardiac pathology in all models. Heart disease severity was associated with the model-dependent frequency of dissemination outside the gut and inferred cumulative heart-specific parasite loads. We propose a model of cardiac pathogenesis driven by periodic trafficking of parasites into the heart, occurring at a frequency determined by host and parasite genetics

Biological factors that impinge on Chagas disease drug development.

Chagas disease is caused by infection with the insect-transmitted protozoan Trypanosoma cruzi, and is the most important parasitic infection in Latin America. The current drugs, benznidazole and nifurtimox, are characterized by limited efficacy and toxic side-effects, and treatment failures are frequently observed. The urgent need for new therapeutic approaches is being met by a combined effort from the academic and commercial sectors, together with major input from not-for-profit drug development consortia. With the disappointing outcomes of recent clinical trials against chronic Chagas disease, it has become clear that an incomplete understanding of parasite biology and disease pathogenesis is impacting negatively on the development of more effective drugs. In addition, technical issues, including difficulties in establishing parasitological cure in both human patients and animal models, have greatly complicated the assessment of drug efficacy. Here, we outline the major questions that need to be addressed and discuss technical innovations that can be exploited to accelerate the drug development pipeline

Hypocretin-2 Saporin Lesions of the Ventrolateral Periaquaductal Gray (vlPAG) Increase REM Sleep in Hypocretin Knockout Mice

Ten years ago the sleep disorder narcolepsy was linked to the neuropeptide hypocretin (HCRT), also known as orexin. This disorder is characterized by excessive day time sleepiness, inappropriate triggering of rapid-eye movement (REM) sleep and cataplexy, which is a sudden loss of muscle tone during waking. It is still not known how HCRT regulates REM sleep or muscle tone since HCRT neurons are localized only in the lateral hypothalamus while REM sleep and muscle atonia are generated from the brainstem. To identify a potential neuronal circuit, the neurotoxin hypocretin-2-saporin (HCRT2-SAP) was used to lesion neurons in the ventral lateral periaquaductal gray (vlPAG). The first experiment utilized hypocretin knock-out (HCRT-ko) mice with the expectation that deletion of both HCRT and its target neurons would exacerbate narcoleptic symptoms. Indeed, HCRT-ko mice (n = 8) given the neurotoxin HCRT2-SAP (16.5 ng/23nl/sec each side) in the vlPAG had levels of REM sleep and sleep fragmentation that were considerably higher compared to HCRT-ko given saline (+39%; n = 7) or wildtype mice (+177%; n = 9). However, cataplexy attacks did not increase, nor were levels of wake or non-REM sleep changed. Experiment 2 determined the effects in mice where HCRT was present but the downstream target neurons in the vlPAG were deleted by the neurotoxin. This experiment utilized an FVB-transgenic strain of mice where eGFP identifies GABA neurons. We verified this and also determined that eGFP neurons were immunopositive for the HCRT-2 receptor. vlPAG lesions in these mice increased REM sleep (+79% versus saline controls) and it was significantly correlated (r = 0.89) with loss of eGFP neurons. These results identify the vlPAG as one site that loses its inhibitory control over REM sleep, but does not cause cataplexy, as a result of hypocretin deficiency

Assessing the Effectiveness of Curative Benznidazole Treatment in Preventing Chronic Cardiac Pathology in Experimental Models of Chagas Disease.

Chagasic heart disease develops in 30% of those infected with the protozoan parasite Trypanosoma cruzi, but can take decades to become symptomatic. Because of this, it has been difficult to assess the extent to which antiparasitic therapy can prevent the development of pathology. We sought to address this question using experimental murine models, exploiting highly sensitive bioluminescent imaging to monitor curative efficacy. Mice were inoculated with bioluminescent parasites and then cured in either the acute or chronic stage of infection with benznidazole. At the experimental endpoint (5 to 6 months postinfection), heart tissue was removed and assessed for inflammation and fibrosis, two widely used markers of cardiac pathology. Infection of BALB/c and C3H/HeN mice with distinct T. cruzi lineages resulted in greatly increased myocardial collagen content at a group level, indicative of fibrotic pathology. When mice were cured by benznidazole in the acute stage, the development of pathology was completely blocked. However, if treatment was delayed until the chronic stage, cardiac fibrosis was observed in the BALB/c model, although the protective effect was maintained in the case of C3H/HeN mice. These experiments therefore demonstrate that curative benznidazole treatment early in murine T. cruzi infections can prevent the development of cardiac fibrosis. They also show that treatment during the chronic stage can block pathology but the effectiveness varies between infection models. If these findings are extendable to humans, it implies that widespread chemotherapeutic intervention targeted at early-stage infections could play a crucial role in reducing Chagas disease morbidity at a population level