640 research outputs found

    Near-infrared resonant photoacoustic gas measurement using simultaneous dual-frequency excitation

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    The simultaneous dual-frequency operation of a resonant photoacoustic gas sensor based on the differential mode excitation photoacoustic (DME-PA) technique is presented. The DME-PA method uses the excitation of two different modes in a resonant photoacoustic cell and the gas concentration is derived from the amplitude ratio of these acoustic modes. With the simultaneous dual-frequency excitation, the amplitude ratio needed by the DME-PA technique is obtained instantaneously, in contrast to the sequential modulation scheme where additional time delays are introduced by changing the modulation frequency. For a given excitation power reaching the photoacoustic cell, and a total acquisition time longer than 7s, the simultaneous modulation scheme provides an improved measurement uncertainty compared to the sequential scheme. The proposed sensor allows measuring water vapour with a ±150 ppmV uncertainty using current-modulated near-infrared LEDs and a 15s total acquisition tim

    Comparing Experiences of Constitutional Reforms to Enshrine the Right to Water in Brazil, Colombia, and Peru: Opportunities and Limitations

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    In this paper we compare recent efforts towards the constitutionalization of the right to water in Brazil, Colombia, and Peru to understand the opportunities and limitations related to the attempts to enhance access to piped water to the highest normative level. Peru passed a constitutional amendment in 2017 while Brazil and Colombia have seen much right-to-water activism but have not succeeded in passing such reforms. We explore the role of the existing domestic legal frameworks on drinkable water provision and water management towards the approval of constitutional amendments. We find that all three countries have specialized laws, water governing institutions, and constitutional jurisprudence connecting access to water with rights, but the legal opportunity structures to enforce socio-economic rights vary; they are stronger in Colombia and Brazil, and weaker in Peru. We argue that legal opportunity structures build legal environments that influence constitutional reform success. Legal opportunity structures act as incentives both for social movements to push for reforms and for actors with legislative power to accept or reject them. Our findings also show that in some contexts political cost is a key element of constitutional reforms that enshrine the right to water; therefore, this is an element that should be considered when analyzing these processes

    Evaluation of clinicopathological features in cats with chronic gastrointestinal signs

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    Food-responsive enteropathy (FRE), idiopathic inflammatory bowel disease (IBD), and alimentary tract lymphoma (AL) are often the remaining differentials for cats presenting with chronic gastrointestinal (GI) signs. Differential diagnosis is further complicated by overlapping clinicopathological features and histopathological changes, however. In this study we describe the clinical presentation of cats with chronic GI signs secondary to FRE, IBD, and AL, and evaluate possible associations between clinical, clinicopathological, ultrasonographic findings and diagnosis. The medical records of client-owned cats with chronic GI signs secondary to FRE, IBD, and AL were reviewed. Univariate and multivariate logistic regression models and receiver-operating characteristic curve (ROC) analysis were used for testing the data. Of the 56 cats included in the study, 22 were diagnosed with FRE (mean age, 70 months ± 49), 17 with IBD (mean age, 101 months ± 40), and 17 with AL (mean age, 122 months ± 45). Cats with FRE were younger and presented more often with diarrhea and less frequently with muscle wasting than cats with IBD or AL. In cats with AL, serum cobalamin levels were lower than in those with FRE or IBD (239 ± 190 ng/L vs. 762 ± 408 ng/L and 625 ± 443 ng/L, respectively) and folate levels were higher than in cats with IBD (18.2 ± 4.2 μg/L vs. 9.1 ± 4.7 μg/L, respectively). Multivariate/ROC curve analysis showed increased values of BUN (sensitivity 100, specificity 29.4, criterion >37 mg/dl) and serum folate (sensitivity 80, specificity 100, criterion >15.6 μg/L) and reduced values of cobalamin (sensitivity 100, specificity 62.5, criterion â¤540 ng/L), which suggested a diagnosis of AL versus IBD. Some clinicopathological features evaluated at diagnosis might suggest AL; however, because differentiating AL from IBD is often difficult, definitive diagnosis should be based on invasive diagnostic workup

    Comparing Experiences of Constitutional Reforms to Enshrine the Right to Water in Brazil, Colombia, and Peru: Opportunities and Limitations

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    In this paper we compare recent efforts towards the constitutionalization of the right to water in Brazil, Colombia, and Peru to understand the opportunities and limitations related to the attempts to enhance access to piped water to the highest normative level. Peru passed a constitutional amendment in 2017 while Brazil and Colombia have seen much right-to-water activism but have not succeeded in passing such reforms. We explore the role of the existing domestic legal frameworks on drinkable water provision and water management towards the approval of constitutional amendments. We find that all three countries have specialized laws, water governing institutions, and constitutional jurisprudence connecting access to water with rights, but the legal opportunity structures to enforce socio-economic rights vary; they are stronger in Colombia and Brazil, and weaker in Peru. We argue that legal opportunity structures build legal environments that influence constitutional reform success. Legal opportunity structures act as incentives both for social movements to push for reforms and for actors with legislative power to accept or reject them. Our findings also show that in some contexts political cost is a key element of constitutional reforms that enshrine the right to water; therefore, this is an element that should be considered when analyzing these processes.publishedVersio

    A case cluster demonstrating the relationship between HLA concordance and virologic and disease outcomes in human immunodeficiency virus infection

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    AbstractWe present a detailed analysis of sexual HIV transmission from one source partner to two recipients. The HLA haplotypes between the source partner and one recipient were very similar with 7 out of 8 HLA alleles from four loci (HLA A, B, C and DRB) shared, while the other recipient shared only one allele. The immunologic outcomes between the two recipients differed dramatically, despite the absence of apparent virologic differences in their inoculums. We suggest that non-viral factors, which might be related to differences in the HLA profile, played a role in determining different CD4+ T-cells dynamics for these two recipients

    Willingness to Participate in HIV Research at the End of Life (EOL)

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    Introduction Animal models have been vital for scientific discovery but have limitations, especially in infectious disease research. It is essential to develop a means to study these diseases in human models. We hypothesized that altruistic people would willingly participate in research near the end-of-life (EOL), for the benefit of science and to provide one last gift to society. Methodology Two surveys were administered to 377 self-reported HIV-negative and 96 HIV-positive individuals. Hypothetical questions assessed their willingness to participate in altruistic research in the last 6 months of life, which might result in a shortened lifespan or physical discomforts. The self-reported HIV-negative group was also asked about willingness to be exposed to infectious pathogens for the sake of research. Results Almost all responders expressed willingness to participate in research at the EOL, regardless of HIV-status. The majority of participants were willing to endure physical discomfort for the sake of research. ‘Blood draws’ was identified as the most tolerable physical discomfort (>70% in both groups). In both groups, >60% were willing to shorten their lifespans for the sake of research. A third of the self-reported HIV-negative group expressed willingness to be exposed to at least one infectious agent to participate in EOL research. Conclusions Our exploratory study demonstrates that people would welcome the opportunity to participate in altruistic research near the EOL. Such research could greatly impact the way infectious disease research is conducted. This study is limited however by its hypothetical nature. Further research is necessary to confirm this interest in those with terminal illness before any further clinical research effort at the EOL can be performed
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