547 research outputs found

    Design of a fatigue test bench in rotary flexion to evaluate the behavior to cyclical loads

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    The development of this article shows the process of design, construction and start-up of a fatigue machine in rotary flexion. Fatigue is a subject of considerable relevance and requires adequate equipment for its study, therefore it is sought to contribute to educational and research growth through the development of a functional fatigue machine and where a variety of materials can be studied. The main results were the development of a machine that can carry out a totally inverted stress of 977 Mpa, therefore it can arrive to study steels of high resistance. This machine follows the standards of the normative ASTM E-466 regarding the dimensions of the test specimen. The design of the machine is divided into 3 systems, mechanical system, electrical system and electronic system. When joining these systems obtained a functional and autonomous machine where can make serious and reliable investigations.The development of this article shows the process of design, construction and start-up of a fatigue machine in rotary flexion. Fatigue is a subject of considerable relevance and requires adequate equipment for its study, therefore it is sought to contribute to educational and research growth through the development of a functional fatigue machine and where a variety of materials can be studied. The main results were the development of a machine that can carry out a totally inverted stress of 977 Mpa, therefore it can arrive to study steels of high resistance. This machine follows the standards of the normative ASTM E-466 regarding the dimensions of the test specimen. The design of the machine is divided into 3 systems, mechanical system, electrical system and electronic system. When joining these systems obtained a functional and autonomous machine where can make serious and reliable investigations

    Design of a fatigue test bench in rotary flexion to evaluate the behavior to cyclical loads

    Get PDF
    The development of this article shows the process of design, construction and start-up of a fatigue machine in rotary flexion. Fatigue is a subject of considerable relevance and requires adequate equipment for its study, therefore it is sought to contribute to educational and research growth through the development of a functional fatigue machine and where a variety of materials can be studied. The main results were the development of a machine that can carry out a totally inverted stress of 977 Mpa, therefore it can arrive to study steels of high resistance. This machine follows the standards of the normative ASTM E-466 regarding the dimensions of the test specimen. The design of the machine is divided into 3 systems, mechanical system, electrical system and electronic system. When joining these systems obtained a functional and autonomous machine where can make serious and reliable investigations.The development of this article shows the process of design, construction and start-up of a fatigue machine in rotary flexion. Fatigue is a subject of considerable relevance and requires adequate equipment for its study, therefore it is sought to contribute to educational and research growth through the development of a functional fatigue machine and where a variety of materials can be studied. The main results were the development of a machine that can carry out a totally inverted stress of 977 Mpa, therefore it can arrive to study steels of high resistance. This machine follows the standards of the normative ASTM E-466 regarding the dimensions of the test specimen. The design of the machine is divided into 3 systems, mechanical system, electrical system and electronic system. When joining these systems obtained a functional and autonomous machine where can make serious and reliable investigations

    Design of a fatigue test bench in rotary flexion to evaluate the behavior to cyclical loads

    Get PDF
    The development of this article shows the process of design, construction and start-up of a fatigue machine in rotary flexion. Fatigue is a subject of considerable relevance and requires adequate equipment for its study, therefore it is sought to contribute to educational and research growth through the development of a functional fatigue machine and where a variety of materials can be studied. The main results were the development of a machine that can carry out a totally inverted stress of 977 Mpa, therefore it can arrive to study steels of high resistance. This machine follows the standards of the normative ASTM E-466 regarding the dimensions of the test specimen. The design of the machine is divided into 3 systems, mechanical system, electrical system and electronic system. When joining these systems obtained a functional and autonomous machine where can make serious and reliable investigations.The development of this article shows the process of design, construction and start-up of a fatigue machine in rotary flexion. Fatigue is a subject of considerable relevance and requires adequate equipment for its study, therefore it is sought to contribute to educational and research growth through the development of a functional fatigue machine and where a variety of materials can be studied. The main results were the development of a machine that can carry out a totally inverted stress of 977 Mpa, therefore it can arrive to study steels of high resistance. This machine follows the standards of the normative ASTM E-466 regarding the dimensions of the test specimen. The design of the machine is divided into 3 systems, mechanical system, electrical system and electronic system. When joining these systems obtained a functional and autonomous machine where can make serious and reliable investigations

    Unique Features of HLA-Mediated HIV Evolution in a Mexican Cohort: A Comparative Study

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    Background: Mounting evidence indicates that HLA-mediated HIV evolution follows highlystereotypic pathways that result in HLA-associated footprints in HIV at the population level.However, it is not known whether characteristic HLA frequency distributions in differentpopulations have resulted in additional unique footprints. Methods: The phylogenetic dependency network model was applied to assess HLA-mediatedevolution in datasets of HIV pol sequences from free plasma viruses and peripheral bloodmononuclear cell (PBMC)-integrated proviruses in an immunogenetically unique cohort of Mexicanindividuals. Our data were compared with data from the IHAC cohort, a large multi-center cohortof individuals from Canada, Australia and the USA.Results: Forty three different HLA-HIV codon associations representing 30 HLA-HIV codon pairswere observed in the Mexican cohort (q < 0.2). Strikingly, 23 (53%) of these associations differedfrom those observed in the well-powered IHAC cohort, strongly suggesting the existence of uniquecharacteristics in HLA-mediated HIV evolution in the Mexican cohort. Furthermore, 17 of the 23novel associations involved HLA alleles whose frequencies were not significantly different fromthose in IHAC, suggesting that their detection was not due to increased statistical power but todifferences in patterns of epitope targeting. Interestingly, the consensus differed in four positionsbetween the two cohorts and three of these positions could be explained by HLA-associated selection. Additionally, different HLA-HIV codon associations were seen when comparing HLAmediatedselection in plasma viruses and PBMC archived proviruses at the population level, with asignificantly lower number of associations in the proviral dataset. Conclusion: Our data support universal HLA-mediated HIV evolution at the population level,resulting in detectable HLA-associated footprints in the circulating virus. However, it also stronglysuggests that unique genetic backgrounds in different HIV-infected populations may influence HIVevolution in a particular direction as particular HLA-HIV codon associations are determined byspecific HLA frequency distributions. Our analysis also suggests a dynamic HLA-associatedevolution in HIV with fewer HLA-HIV codon associations observed in the proviral compartment,which is likely enriched in early archived HIV sequences, compared to the plasma viruscompartment. These results highlight the importance of comparative HIV evolutionary studies inimmunologically different populations worldwide

    Clinical impact of pretreatment human immunodeficiency virus drug resistance in people initiating nonnucleoside reverse transcriptase inhibitor-containing antiretroviral therapy: a systematic review and meta-analysis

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    Background: Increased access to antiretroviral therapy (ART) has resulted in rising levels of pretreatment human immunodeficiency virus drug resistance (PDR). This is the first systematic review and meta-analysis to assess the impact of PDR on treatment outcomes among people initiating nonnucleoside reverse transcriptase inhibitor (NNRTI)-based ART, including the combination of efavirenz (EFV), tenofovir (TDF), and lamivudine or emtricitabine (XTC). Methods: We systematically reviewed studies and conference proceedings comparing treatment outcomes in populations initiating NNRTI-based ART with and without PDR. We conducted subgroup analyses by regimen: (1) NNRTIs + 2 nucleoside reverse transcriptase inhibitors (NRTIs), (2) EFV + 2 NRTIs, or (3) EFV/TDF/XTC; by population (children vs adults); and by definition of resistance (PDR vs NNRTI PDR). Results: Among 6197 studies screened, 32 were analyzed (31 441 patients). We found that individuals with PDR initiating NNRTIs across all the subgroups had increased risk of virological failure compared to those without PDR. Risk of acquisition of new resistance mutations and ART switch was also higher in people with PDR. Conclusions: This review shows poorer treatment outcomes in the presence of PDR, supporting the World Health Organization's recommendation to avoid using NNRTIs in countries where levels of PDR are high

    Recommendations on data sharing in HIV drug resistance research

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    • Human immunodeficiency virus (HIV) drug resistance has implications for antiretroviral treatment strategies and for containing the HIV pandemic because the development of HIV drug resistance leads to the requirement for antiretroviral drugs that may be less effective, less well-tolerated, and more expensive than those used in first-line regimens.  • HIV drug resistance studies are designed to determine which HIV mutations are selected by antiretroviral drugs and, in turn, how these mutations affect antiretroviral drug susceptibility and response to future antiretroviral treatment regimens.  • Such studies collectively form a vital knowledge base essential for monitoring global HIV drug resistance trends, interpreting HIV genotypic tests, and updating HIV treatment guidelines.  • Although HIV drug resistance data are collected in many studies, such data are often not publicly shared, prompting the need to recommend best practices to encourage and standardize HIV drug resistance data sharing.  • In contrast to other viruses, sharing HIV sequences from phylogenetic studies of transmission dynamics requires additional precautions as HIV transmission is criminalized in many countries and regions.  • Our recommendations are designed to ensure that the data that contribute to HIV drug resistance knowledge will be available without undue hardship to those publishing HIV drug resistance studies and without risk to people living with HIV

    HIV-1 drug resistance before initiation or re-initiation of first-line antiretroviral therapy in low-income and middle-income countries: a systematic review and meta-regression analysis.

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    BACKGROUND: Pretreatment drug resistance in people initiating or re-initiating antiretroviral therapy (ART) containing non-nucleoside reverse transcriptase inhibitors (NNRTIs) might compromise HIV control in low-income and middle-income countries (LMICs). We aimed to assess the scale of this problem and whether it is associated with the intiation or re-initiation of ART in people who have had previous exposure to antiretroviral drugs. METHODS: This study was a systematic review and meta-regression analysis. We assessed regional prevalence of pretreatment drug resistance and risk of pretreatment drug resistance in people initiating ART who reported previous ART exposure. We systematically screened publications and unpublished datasets for pretreatment drug-resistance data in individuals in LMICs initiating or re-initiating first-line ART from LMICs. We searched for studies in PubMed and Embase and conference abstracts and presentations from the Conference on Retroviruses and Opportunistic Infections, the International AIDS Society Conference, and the International Drug Resistance Workshop for the period Jan 1, 2001, to Dec 31, 2016. To assess the prevalence of drug resistance within a specified region at any specific timepoint, we extracted study level data and pooled prevalence estimates within the region using an empty logistic regression model with a random effect at the study level. We used random effects meta-regression to relate sampling year to prevalence of pretreatment drug resistance within geographical regions. FINDINGS: We identified 358 datasets that contributed data to our analyses, representing 56 044 adults in 63 countries. Prevalence estimates of pretreatment NNRTI resistance in 2016 were 11·0% (7·5-15·9) in southern Africa, 10·1% (5·1-19·4) in eastern Africa, 7·2% (2·9-16·5) in western and central Africa, and 9·4% (6·6-13·2) in Latin America and the Caribbean. There were substantial increases in pretreatment NNRTI resistance per year in all regions. The yearly increases in the odds of pretreatment drug resistance were 23% (95% CI 16-29) in southern Africa, 17% (5-30) in eastern Africa, 17% (6-29) in western and central Africa, 11% (5-18) in Latin America and the Caribbean, and 11% (2-20) in Asia. Estimated increases in the absolute prevalence of pretreatment drug resistance between 2015 and 2016 ranged from 0·3% in Asia to 1·8% in southern Africa. INTERPRETATION: Pretreatment drug resistance is increasing at substantial rate in LMICs, especially in sub-Saharan Africa. In 2016, the prevalence of pretreatment NNRTI resistance was near WHO's 10% threshold for changing first-line ART in southern and eastern Africa and Latin America, underscoring the need for routine national HIV drug-resistance surveillance and review of national policies for first-line ART regimen composition. FUNDING: Bill & Melinda Gates Foundation and World Health Organization

    Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

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    Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

    Juxtaposing BTE and ATE – on the role of the European insurance industry in funding civil litigation

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    One of the ways in which legal services are financed, and indeed shaped, is through private insurance arrangement. Two contrasting types of legal expenses insurance contracts (LEI) seem to dominate in Europe: before the event (BTE) and after the event (ATE) legal expenses insurance. Notwithstanding institutional differences between different legal systems, BTE and ATE insurance arrangements may be instrumental if government policy is geared towards strengthening a market-oriented system of financing access to justice for individuals and business. At the same time, emphasizing the role of a private industry as a keeper of the gates to justice raises issues of accountability and transparency, not readily reconcilable with demands of competition. Moreover, multiple actors (clients, lawyers, courts, insurers) are involved, causing behavioural dynamics which are not easily predicted or influenced. Against this background, this paper looks into BTE and ATE arrangements by analysing the particularities of BTE and ATE arrangements currently available in some European jurisdictions and by painting a picture of their respective markets and legal contexts. This allows for some reflection on the performance of BTE and ATE providers as both financiers and keepers. Two issues emerge from the analysis that are worthy of some further reflection. Firstly, there is the problematic long-term sustainability of some ATE products. Secondly, the challenges faced by policymakers that would like to nudge consumers into voluntarily taking out BTE LEI

    Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan

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    This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good
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