601 research outputs found

    Router security effect on performance of a network

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    Recently many of the devices that create a computer network offer security to help protect networks from hackers, such as computers, servers, firewalls and even routers. In most cases when protecting a network from hackers having more security is not always the best, because the more resources of the device is used by the security in inspecting connections, and it can compromise performance of the network. This thesis investigates performance benefit of having security on a router and its impact on the connection rate of the network when it is under security attacks. In this thesis, different security features and configurations offered by the router are tested to see how they affect the connection rate of the network under different security attacks, and compare with the benchmark network performance when there was no security used at all in the router

    Engajamento Político Transnacional e a Incorporação Cívica de Imigrantes Mexicanos nos Estados Unidos

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    Many migrants to the U.S. are engaged in public affairs in their country of origin. Whether such engagement impedes or encourages engagement in American politics remains an open question. Drawing from a unique two-wave panel survey of Mexican immigrants conducted in 2006, with surveys waves fielded to correspond to national elections in Mexico and the United States, we examine the relationship between transnational political engagement and attentiveness to American politics. The findings indicate that remote political engagement in Mexican politics is not a barrier to incorporation in the U.S. context. On the contrary, engagement in Mexican campaigns can stimulate interest and participation in U.S. elections.Muchos de los migrantes a los Estados Unidos se involucran en la vida cívica de su país de origen. Es pregunta abierta si tal participación impide o promueve la participación en la política norteamericana. Utilizando datos de una encuesta de inmigrantes mexicanos en dos olas llevadas a cabo en 2006, coordinadas con las elecciones nacionales en México y los Estados Unidos, investigamos la relación entre la participación política trasnacional y la atención a la política norteamericana. Los hallazgos señalan que la participación en la política mexicana no es obstáculo a la incorporación cívica en el contexto norteamericano. Al contrario, la atención a las campañas mexicanas puede estimular el interés y la participación en las elecciones estadunidenses.Muitas pessoas que migram para os Estados Unidos continuam engajadas em assuntos públicos em seu país de origem, mas não está claro se esse engajamento impede ou incentiva o envolvimento na política americana. O presente estudo examina a relação entre o engajamento político transnacional e a atenção à política americana, com base em uma pesquisa de painel de duas ondas realizada com imigrantes mexicanos em 2006. As duas ondas da pesquisa correspondem às eleições nacionais no México e nos Estados Unidos. Os resultados indicam que o engajamento à distância na política mexicana não é uma barreira para a incorporação no contexto dos Estados Unidos. Pelo contrário, o engajamento em campanhas mexicanas pode estimular o interesse e a participação nas eleições americanas

    The Politics of Latino Education: The Biases of At-Large Elections

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    This paper investigates the determinants and consequences of Latino political representation in the field of K-12 education. The first task is to examine the association between Latino population and the Latino presence on school boards. We then investigate if Latino representation is affected by the electoral structure of school boards, as scholars have reached differing conclusions on whether at-large and ward systems hinder or enhance minority descriptive representation. The next step exam-ines the consequences of Latino representation, specifically whether board membership is associated with the share of Latino school administrators and teachers. The regression results show that Latino population positively affects Latino board representation, but that at-large systems hinder descriptive representation. The primary determinant of Latino administrators is Latino school board member-ship, and the primary determinant of Latino teachers is Latino administrators. In sum, at-large elec-tions negatively influence Latino educational representation, which produces a ripple effect that ultimately reduces the share of Latino teachers. Latinos are now the largest minority group in the United States, but numbers alone are no guarantee of political influence. The traditional view of how minori-ties gain access to the benefits of the U.S. political system is via education, bu

    AMI observations of unmatched Planck ERCSC LFI sources at 15.75 GHz

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    The Planck Early Release Compact Source Catalogue includes 26 sources with no obvious matches in other radio catalogues (of primarily extragalactic sources). Here we present observations made with the Arcminute Microkelvin Imager Small Array (AMI SA) at 15.75 GHz of the eight of the unmatched sources at declination > +10 degrees. Of the eight, four are detected and are associated with known objects. The other four are not detected with the AMI SA, and are thought to be spurious.Comment: 6 pages, 5 figures, 4 table

    Managing carious lesions:consensus recommendations on carious tissue removal

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    The International Caries Consensus Collaboration undertook a consensus process and here presents clinical recommendations for carious tissue removal and managing cavitated carious lesions, including restoration, based on texture of demineralized dentine. Dentists should manage the disease dental caries and control activity of existing cavitated lesions to preserve hard tissues and retain teeth long-term. Entering the restorative cycle should be avoided as far as possible. Controlling the disease in cavitated carious lesions should be attempted using methods which are aimed at biofilm removal or control first. Only when cavitated carious lesions either are noncleansable or can no longer be sealed are restorative interventions indicated. When a restoration is indicated, the priorities are as follows: preserving healthy and remineralizable tissue, achieving a restorative seal, maintaining pulpal health, and maximizing restoration success. Carious tissue is removed purely to create conditions for long-lasting restorations. Bacterially contaminated or demineralized tissues close to the pulp do not need to be removed. In deeper lesions in teeth with sensible (vital) pulps, preserving pulpal health should be prioritized, while in shallow or moderately deep lesions, restoration longevity becomes more important. For teeth with shallow or moderately deep cavitated lesions, carious tissue removal is performed according toselective removal to firm dentine.In deep cavitated lesions in primary or permanent teeth,selective removal to soft dentineshould be performed, although in permanent teeth,stepwise removalis an option. The evidence and, therefore, these recommendations support less invasive carious lesion management, delaying entry to, and slowing down, the restorative cycle by preserving tooth tissue and retaining teeth long-term.status: publishe

    Abnormal Capillary Vasodynamics Contribute to Ictal Neurodegeneration in Epilepsy

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    Seizure-driven brain damage in epilepsy accumulates over time, especially in the hippocampus, which can lead to sclerosis, cognitive decline, and death. Excitotoxicity is the prevalent model to explain ictal neurodegeneration. Current labeling technologies cannot distinguish between excitotoxicity and hypoxia, however, because they share common molecular mechanisms. This leaves open the possibility that undetected ischemic hypoxia, due to ictal blood flow restriction, could contribute to neurodegeneration previously ascribed to excitotoxicity. We tested this possibility with Confocal Laser Endomicroscopy (CLE) and novel stereological analyses in several models of epileptic mice. We found a higher number and magnitude of NG2+ mural-cell mediated capillary constrictions in the hippocampus of epileptic mice than in that of normal mice, in addition to spatial coupling between capillary constrictions and oxidative stressed neurons and neurodegeneration. These results reveal a role for hypoxia driven by capillary blood flow restriction in ictal neurodegeneration

    Abnormal Capillary Vasodynamics Contribute to Ictal Neurodegeneration in Epilepsy

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    Seizure-driven brain damage in epilepsy accumulates over time, especially in the hippocampus, which can lead to sclerosis, cognitive decline, and death. Excitotoxicity is the prevalent model to explain ictal neurodegeneration. Current labeling technologies cannot distinguish between excitotoxicity and hypoxia, however, because they share common molecular mechanisms. This leaves open the possibility that undetected ischemic hypoxia, due to ictal blood flow restriction, could contribute to neurodegeneration previously ascribed to excitotoxicity. We tested this possibility with Confocal Laser Endomicroscopy (CLE) and novel stereological analyses in several models of epileptic mice. We found a higher number and magnitude of NG2+ mural-cell mediated capillary constrictions in the hippocampus of epileptic mice than in that of normal mice, in addition to spatial coupling between capillary constrictions and oxidative stressed neurons and neurodegeneration. These results reveal a role for hypoxia driven by capillary blood flow restriction in ictal neurodegeneration

    Positive Selection of a Pre-Expansion CAG Repeat of the Human SCA2 Gene

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    A region of approximately one megabase of human Chromosome 12 shows extensive linkage disequilibrium in Utah residents with ancestry from northern and western Europe. This strikingly large linkage disequilibrium block was analyzed with statistical and experimental methods to determine whether natural selection could be implicated in shaping the current genome structure. Extended Haplotype Homozygosity and Relative Extended Haplotype Homozygosity analyses on this region mapped a core region of the strongest conserved haplotype to the exon 1 of the Spinocerebellar ataxia type 2 gene (SCA2). Direct DNA sequencing of this region of the SCA2 gene revealed a significant association between a pre-expanded allele [(CAG)(8)CAA(CAG)(4)CAA(CAG)(8)] of CAG repeats within exon 1 and the selected haplotype of the SCA2 gene. A significantly negative Tajima's D value (−2.20, p < 0.01) on this site consistently suggested selection on the CAG repeat. This region was also investigated in the three other populations, none of which showed signs of selection. These results suggest that a recent positive selection of the pre-expansion SCA2 CAG repeat has occurred in Utah residents with European ancestry

    High-accuracy determination of the U 238 / U 235 fission cross section ratio up to ≈1 GeV at n-TOF at CERN

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    Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOIThe U238 to U235 fission cross section ratio has been determined at n-TOF up to ≈1 GeV, with two different detection systems, in different geometrical configurations. A total of four datasets has been collected and compared. They are all consistent to each other within the relative systematic uncertainty of 3-4%. The data collected at n-TOF have been suitably combined to yield a unique fission cross section ratio as a function of neutron energy. The result confirms current evaluations up to 200 MeV. Good agreement is also observed with theoretical calculations based on the INCL++/Gemini++ combination up to the highest measured energy. The n-TOF results may help solve a long-standing discrepancy between the two most important experimental datasets available so far above 20 MeV, while extending the neutron energy range for the first time up to ≈1 GeV.Peer reviewedFinal Published versio
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