3,346 research outputs found

    Breeding habits and habitats of the amphibians of the Edwin S. George Reserve, Michigan, with notes on the local distribution of fishes

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    http://deepblue.lib.umich.edu/bitstream/2027.42/57122/1/OP686.pd

    Vibratory Loads Data from a Wind-Tunnel Test of Structurally Tailored Model Helicopter Rotors

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    An experimental study was conducted in the Langley Transonic Dynamics Tunnel to investigate the use of a Bell Helicopter Textron (BHT) rotor structural tailoring concept, known as rotor nodalization, in conjunction with advanced blade aerodynamics as well as to evaluate rotor blade aerodynamic design methodologies. A 1/5-size, four-bladed bearingless hub, three sets of Mach-scaled model rotor blades were tested in forward flight from transition up to an advance ratio of 0.35. The data presented pertain only to the evaluation of the structural tailoring concept and consist of fixed-system and rotating system vibratory loads. These data will be useful for evaluating the effects of tailoring blade structural properties on fixed-system vibratory loads, as well as validating analyses used in the design of advanced rotor systems

    STATISTICAL ISSUES IN THE ANALYSIS OF MICROBIAL COMMUNITIES IN SOIL

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    Corn and soybean production dominates the agricultural systems of the mid-western United States. Studies have found that when a single crop species is grown continually, without the rotation of other crops, yield decline occurs. At present, this phenomenon, remains poorly understood, but there are possible links to microbial community dynamics in the associated rhizosphere soil. In this study, corn plants were grown in disturbed and undisturbed soils with a 24 year history of growth as a mono culture crop or two crops grown in annual rotation. Characteristic profiles of the microbial communities were obtained by denaturing gradient gel electrophoresis of polymerase chain reaction amplified 16S rDNA from soil extracted DNA. This problem is approached as the statistical analysis of high-dimensional multivariate binary data with an emphasis on modeling and variable selection

    Thermal noise limitations to force measurements with torsion pendulums: Applications to the measurement of the Casimir force and its thermal correction

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    A general analysis of thermal noise in torsion pendulums is presented. The specific case where the torsion angle is kept fixed by electronic feedback is analyzed. This analysis is applied to a recent experiment that employed a torsion pendulum to measure the Casimir force. The ultimate limit to the distance at which the Casimir force can be measured to high accuracy is discussed, and in particular the prospects for measuring the thermal correction are elaborated upon.Comment: one figure, five pages, to be submitted to Phys Rev

    Creating the Back Ward: The Triumph of Custodialism and the Uses of Therapeutic Failure in Nineteenth Century Idiot Asylums

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    My focus in this chapter is on the origin of the back ward rather than its demise. Where did the “back wards” that [Burton] Blatt and [Senator Robert] Kennedy witnessed come from in the first place? What 3 exactly were those “antecedents of the problems observed” that Blatt cited? This chapter reviews that history and argues that, in fact, there is a specific narrative to the evolution of the institutional “back ward” as an identifiable place where people with the most significant intellectual disabilities were to be incarcerated and largely forgotten.https://digitalcommons.chapman.edu/education_books/1006/thumbnail.jp

    Microvascular cerebral hemodynamics in pediatric sickle cell disease with Diffuse Correlation Spectroscopy

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    Sickle cell disease is a genetic blood disorder that has profound effects on the brain. Chronic anemia combined with both macro- and micro-vascular perfusion abnormalities that arise from stenosis or occlusion of blood vessels, increased blood viscosity, adherence of red blood cells to the vascular endothelium, and impaired autoregulatory mechanisms in sickle cell disease patients all culminate in susceptibility to cerebral infarction. Indeed, the risk of stroke is 250 times higher in children with sickle cell disease than in the general population. Unfortunately, while transcranial Doppler ultrasound (TCD) has been widely clinically adopted to longitudinally monitor macrovascular perfusion in these patients, routine clinical screening of microvascular perfusion abnormalities is challenging with current modalities (e.g., positron emission tomography, magnetic resonance imaging) given their high-cost, requirement for sedation in children \u3c 6y, and need for trained personnel. In this pilot study, we first assess the feasibility of a low-cost, noninvasive optical technique known as Diffuse Correlation Spectroscopy (DCS) to quantify an index of resting-state cortical cerebral blood flow in 11 children with SCD along with 11 sex- and age-matched healthy controls. As expected, blood flow index was significantly higher in sickle subjects compared to healthy controls (p \u3c 0.001). Within sickle subjects, blood flow index was inversely proportional to resting-state arterial hemoglobin levels (p = 0.012), consistent with expected anemia-induced compensatory vasodilation that aims to maintain adequate oxygen delivery to the tissue. Further, in a subset of patients measured with transcranial Doppler ultrasound, DCS-measured blood flow was correlated with TCD-measured blood flow velocity in middle cerebral artery (Rs = 0.68), although the trend was not statistically significant (p=0.11). These results are consistent with those of several previous studies using traditional neuroimaging techniques to quantify cerebral blood flow, suggesting that DCS may be a promising low-cost tool for assessment of tissue-level cerebral blood flow in pediatric sickle cell disease. Finally, given that sickle cell disease is often associated with severe anemia, we next assessed the potentially confounding effects of hematocrit on the DCS-measured blood flow index using a microfluidic tissue-simulating phantom. For a fixed flow rate in the microfluidic channels, we show that blood flow index is inversely correlated with hematocrit, and we present a means to correct the measured blood flow index for hematocrit in anemic conditions

    How to Get the Most out of Your Curation Effort

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    Large-scale annotation efforts typically involve several experts who may disagree with each other. We propose an approach for modeling disagreements among experts that allows providing each annotation with a confidence value (i.e., the posterior probability that it is correct). Our approach allows computing certainty-level for individual annotations, given annotator-specific parameters estimated from data. We developed two probabilistic models for performing this analysis, compared these models using computer simulation, and tested each model's actual performance, based on a large data set generated by human annotators specifically for this study. We show that even in the worst-case scenario, when all annotators disagree, our approach allows us to significantly increase the probability of choosing the correct annotation. Along with this publication we make publicly available a corpus of 10,000 sentences annotated according to several cardinal dimensions that we have introduced in earlier work. The 10,000 sentences were all 3-fold annotated by a group of eight experts, while a 1,000-sentence subset was further 5-fold annotated by five new experts. While the presented data represent a specialized curation task, our modeling approach is general; most data annotation studies could benefit from our methodology

    Engineering tyrosine-based electron flow pathways in proteins: The case of aplysia myoglobin

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    Tyrosine residues can act as redox cofactors that provide an electron transfer ("hole-hopping") route that enhances the rate of ferryl heme iron reduction by externally added reductants, for example, ascorbate. Aplysia fasciata myoglobin, having no naturally occurring tyrosines but 15 phenylalanines that can be selectively mutated to tyrosine residues, provides an ideal protein with which to study such through-protein electron transfer pathways and ways to manipulate them. Two surface exposed phenylalanines that are close to the heme have been mutated to tyrosines (F42Y, F98Y). In both of these, the rate of ferryl heme reduction increased by up to 3 orders of magnitude. This result cannot be explained in terms of distance or redox potential change between donor and acceptor but indicates that tyrosines, by virtue of their ability to form radicals, act as redox cofactors in a new pathway. The mechanism is discussed in terms of the Marcus theory and the specific protonation/deprotonation states of the oxoferryl iron and tyrosine. Tyrosine radicals have been observed and quantified by EPR spectroscopy in both mutants, consistent with the proposed mechanism. The location of each radical is unambiguous and allows us to validate theoretical methods that assign radical location on the basis of EPR hyperfine structure. Mutation to tyrosine decreases the lipid peroxidase activity of this myoglobin in the presence of low concentrations of reductant, and the possibility of decreasing the intrinsic toxicity of hemoglobin by introduction of these pathways is discussed. © 2012 American Chemical Society
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