505 research outputs found

    Catching Bacteria with Sugar

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    In this issue of Chemistry & Biology, Disney and Seeberger exploit bacterial targeting of host cell surface sugars during pathogenesis to create a simple diagnostic carbohydrate microarray for the detection of bacteria in complex biological mixtures [1]

    Experimental investigation on a novel integrated solar chimney and liquid desiccant system for simultaneous power and fresh water generation

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    Electric power and water play a pivotal role in all aspects of daily life. In attempts to provide renewable energy-sourced systems for the concurrent generation of power and fresh water, a few studies have been conducted over the last two decades to combine solar chimney power plant (SCPP) with fresh water production systems (FWPS). These studies have mostly been theoretical approaches with significant feasibility limitations. In this article, a novel solar-powered hybrid generator of power and fresh water is presented, where SCPP has been combined with liquid desiccant system( LDS) to simultaneously produce power and fresh water. This combination utilizes the advantages of LDS of calcium chloride to turn the SCPP working air humidity into fresh water. A pilot plant of this technology was designed, constructed, and tested on an hourly basis over ten randomly selected days in October-December 2018. Consequently, its concept of operation was proven. It was concluded that using this technology and under daily averages of solar irradiance of 500 W/m2 and atmospheric air humidity ratio of 0.019 (kg water vapour/ kg dry air), a combination of power generation capacity higher than 50 MW could economically produce power and fresh water. Furthermore, an average of 5.6 l/hr of fresh water could be produced per 1 kg/s of SCPP working air. Nevertheless, the current technology enables using a wide controllable range (0%-100%) of SCPP produced power to generate fresh water

    A Systems Approach to Understanding the Role of Glycans in Cancer

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    Glycosylation involves the post-translational addition of carbohydrates to protein molecules and is an intricate and indispensable biochemical process. Study of this complicated network of interactions is hindered by the lack of a coding template analogous to the genetic code, and by the vast structural complexity inherent to carbohydrate polymers. We use lectins (non-enzymatic carbohydrate-binding proteins of non-immunological origin) as microarray probes to identify carbohydrate features expressed on cellular surfaces. Specifically, we utilized lectin microarray technology to investigate the differences in carbohydrates expressed by the cell lines of the Nation Cancer Institute’s NCI-60 panel. Our investigation identified tissue-specific expression differences in high-mannose N-linked glycans as a result of microRNA-based regulation of key processing enzymes in the N-linked biosynthetic pathway. Thus post-transcriptional regulation at the RNA level affects glycome characteristics

    An Integrated Systems Approach to Deconstructing Glycosylation

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    Glycosylation involves the post-translational addition of carbohydrates to protein molecules and is an intricate and indispensable biochemical process. Study of this complicated network of interactions is hindered by the lack of a coding template analogous to the genetic code, and by the vast structural complexity inherent to carbohydrate polymers. We use lectins (non-enzymatic carbohydrate-binding proteins of non-immunological origin) as microarray probes to identify carbohydrate features expressed on cellular surfaces. Specifically, we utilized lectin microarray technology to investigate the differences in carbohydrates expressed by the cell lines of the Nation Cancer Institute’s NCI-60 panel. Our investigation identified tissue-specific expression differences in high-mannose N-linked glycans as a result of microRNA-based regulation of key processing enzymes in the N-linked biosynthetic pathway. Thus post-transcriptional regulation at the RNA level affects glycome characteristics

    Calcium-independent stimulation of membrane fusion and SNAREpin formation by synaptotagmin I

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    Ñeurotransmitter release requires the direct coupling of the calcium sensor with the machinery for membrane fusion. SNARE proteins comprise the minimal fusion machinery, and synaptotagmin I, a synaptic vesicle protein, is the primary candidate for the main neuronal calcium sensor. To test the effect of synaptotagmin I on membrane fusion, we incorporated it into a SNARE-mediated liposome fusion assay. Synaptotagmin I dramatically stimulated membrane fusion by facilitating SNAREpin zippering. This stimulatory effect was topologically restricted to v-SNARE vesicles (containing VAMP 2) and only occurred in trans to t-SNARE vesicles (containing syntaxin 1A and SNAP-25). Interestingly, calcium did not affect the overall fusion reaction. These results indicate that synaptotagmin I can directly accelerate SNARE-mediated membrane fusion and raise the possibility that additional components might be required to ensure tight calcium coupling

    Improved defect detection using adaptive leaky NLMS filter in guided-wave testing of pipelines

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    Ultrasonic guided wave (UGW) testing of pipelines allows long range assessments of pipe integrity from a single point of inspection. This technology uses a number of arrays of transducers, linearly placed apart from each other to generate a single axisymmetric wave mode. The general propagation routine of the device results in a single time domain signal, which is then used by the inspectors to detect the axisymmetric wave for any defect location. Nonetheless, due to inherited characteristics of the UGW and non-ideal testing conditions, non-axisymmetric (flexural) waves will be transmitted and received in the tests. This adds to the complexity of results’ interpretation. In this paper, we implement an adaptive leaky normalized least mean square (NLMS) filter for reducing the effect of non-axisymmetric waves and enhancement of axisymmetric waves. In this approach, no modification in the device hardware is required. This method is validated using the synthesized signal generated by a finite element model (FEM) and real test data gathered from laboratory trials. In laboratory trials, six different sizes of defects with cross-sectional area (CSA) material loss of 8% to 3% (steps of 1%) were tested. To find the optimum frequency, several excitation frequencies in the region of 30–50 kHz (steps of 2 kHz) were used. Furthermore, two sets of parameters were used for the adaptive filter wherein the first set of tests the optimum parameters were set to the FEM test case and, in the second set of tests, the data from the pipe with 4% CSA defect was used. The results demonstrated the capability of this algorithm for enhancing a defect’s signal-to-noise ratio (SNR).NSIRC and Brunel Universit

    Prostate Cancer Disparities in Risk Group at Presentation and Access to Treatment for Asian Americans, Native Hawaiians, and Pacific Islanders: A Study With Disaggregated Ethnic Groups

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    PURPOSE: We identified (1) differences in localized prostate cancer (PCa) risk group at presentation and (2) disparities in access to initial treatment for Asian American, Native Hawaiian, and Pacific Islander (AANHPI) men with PCa after controlling for sociodemographic factors. METHODS: We assessed all patients in the National Cancer Database with localized PCa with low-, intermediate-, and high-risk disease who identified as Thai, White, Asian Indian, Chinese, Vietnamese, Korean, Japanese, Filipino, Hawaiian, Pacific Islander, Laotian, Pakistani, Kampuchean, and Hmong. Multivariable logistic regression defined adjusted odds ratios (AORs) with 95% CI of (1) presenting at progressively higher risk group and (2) receiving treatment or active surveillance with intermediate- or high-risk disease, adjusting for sociodemographic and clinical factors. RESULTS: Among 980,889 men (median age 66 years), all AANHPI subgroups with the exception of Thai (AOR = 0.84 [95% CI, 0.58 to 1.21], P > .05), Asian Indian (AOR = 1.12 [95% CI, 1.00 to 1.25], P > .05), and Pakistani (AOR = 1.34 [95% CI, 0.98 to 1.83], P > .05) men had greater odds of presenting at a progressively higher PCa risk group compared with White patients (Chinese AOR = 1.18 [95% CI, 1.11 to 1.25], P < .001; Japanese AOR = 1.36 [95% CI, 1.26 to 1.47], P < .001; Filipino AOR = 1.37 [95% CI, 1.29 to 1.46], P < .001; Korean AOR = 1.32 [95% CI, 1.18 to 1.48], P < .001; Vietnamese AOR = 1.20 [95% CI, 1.07 to 1.35], P = .002; Laotian AOR = 1.60 [95% CI, 1.08 to 2.36], P = .018; Hmong AOR = 4.07 [95% CI, 1.54 to 10.81], P = .005; Kampuchean AOR = 1.55 [95% CI, 1.03 to 2.34], P = .036; Asian Indian or Pakistani AOR = 1.15 [95% CI, 1.07 to 1.24], P < .001; Native Hawaiians AOR = 1.58 [95% CI, 1.38 to 1.80], P < .001; and Pacific Islanders AOR = 1.58 [95% CI, 1.37 to 1.82], P < .001). Additionally, Japanese Americans (AOR = 1.46 [95% CI, 1.09 to 1.97], P = .013) were more likely to receive treatment compared with White patients. CONCLUSION: Our findings suggest that there are differences in PCa risk group at presentation by race or ethnicity among Asian American, Native Hawaiian, and Pacific Islander subgroups and that there exist disparities in treatment patterns. Although AANHPI are often studied as a homogenous group, heterogeneity upon subgroup disaggregation underscores the importance of further study to assess and address barriers to PCa care

    Atypical clinical presentation of mucopolysaccharidosis type II (Hunter syndrome): a case report

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    <p>Abstract</p> <p>Introduction</p> <p>We present a very rare case of mucopolysaccharidosis with atypical presentation such as mild mental retardation, an acrocephalic head and no corneal clouding. The purpose of presenting this case is to highlight the distinctive manifestation of mucopolysaccharidosis type II (Hunter syndrome).</p> <p>Case presentation</p> <p>A 10-year-old East Asian boy presented with abdominal distension of five years' duration and complained of shortness of breath on and off for the same period. On examination his head was large and his head circumference was 54.5 cm. His neck was short, he had coarse facial features, a depressed nasal bridge and small stubby fingers with flexion of distal interphalangeal joints, and a low arched palate was observed. There was mild mental retardation.</p> <p>Conclusion</p> <p>Based on clinical findings and radiological features it is possible to diagnose a case of mucopolysaccharidosis.</p> <p>Careful and systemic approach is needed to accurately diagnose the exact type as enzymatic studies are not available in most centers.</p

    Nitrogen Fertilizer Suppresses Mineralization of Soil Organic Matter in Maize Agroecosystems

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    The possibility that N fertilizer increases soil organic matter (SOM) mineralization and, as a result, reduces SOM stocks has led to a great debate about the long-term sustainability of maize-based agroecosystems as well as the best method to estimate fertilizer N use efficiency (FNUE). Much of this debate is because synthetic N fertilizer can positively or negatively affect SOM mineralization via several direct and indirect pathways. Here, we test a series of hypotheses to determine the direction, magnitude, and mechanism of N fertilizer effect on SOM mineralization and discuss the implications for methods to estimate FNUE. We measured the effect of synthetic N fertilizer on SOM mineralization via gross ammonification at two long-term experiments in central and southern Iowa, USA with replicated plots of continuous maize that received one of three “historical” N fertilizer rates (zero, moderate or high) from 1999 to 2014. In 2015, prior to our measurements, we split the historical N fertilizer rate plots into two subplots that received either the site-specific agronomic optimum N rate or zero N fertilizer. At the onset of rapid maize N uptake, N fertilizer reduced gross ammonification by 13–21% (2–5 kg NH4-N ha−1 d−1). A companion laboratory experiment rejected the hypothesis that differences in net primary productivity between fertilized and unfertilized treatments explained the negative effect of N fertilizer on SOM mineralization. Moreover, the NH4+ pool size was negatively correlated with the gross ammonification rate (r2 = 0.85, p \u3c 0.001). Thus, we conclude that NH4+ -N fertilizer had a direct suppressive effect on SOM mineralization. These results demonstrate that the direct effect of N fertilizer on microbial activity can exceed the indirect effects of N fertilizer via large changes in NPP that alter organic matter inputs, soil temperature and moisture content. The magnitude of this effect and specificity to NH4+ -N has significant implications for fertilizer management as well as the measurement and modeling of agroecosystem N dynamics including FNUE

    Quality of medical training and emigration of physicians from India

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    <p>Abstract</p> <p>Background</p> <p>Physician 'brain drain' negatively impacts health care delivery. Interventions to address physician emigration have been constrained by lack of research on systematic factors that influence physician migration. We examined the relationship between the quality of medical training and rate of migration to the United States and the United Kingdom among Indian medical graduates (1955–2002).</p> <p>Methods</p> <p>We calculated the fraction of medical graduates who emigrated to the United States and the United Kingdom, based on rankings of medical colleges and universities according to three indicators of the quality of medical education (a) student choice, (b) academic publications, and (c) the availability of specialty medical training.</p> <p>Results</p> <p>Physicians from the top quintile medical colleges and of universities were 2 to 4 times more likely to emigrate to the United States and the United Kingdom than graduates from the bottom quintile colleges and universities.</p> <p>Conclusion</p> <p>Graduates of institutions with better quality medical training have a greater likelihood of emigrating. Interventions designed to counter loss of physicians should focus on graduates from top quality institutions.</p
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