4,379 research outputs found
Constructing two-sided simultaneous confidence intervals for multinomial proportions for small counts in a large number of cells
Confidence intervals for multinomial proportions are often constructed using large-sample methods that rely on expected cell counts of 5 or greater. In situations that give rise to a large number of categories, the cell counts may not be of adequate size to ensure the appropriate overall coverage probability and alternative methods of construction have been proposed. Sison and Glaz (1995) developed a method of constructing two-sided confidence intervals for multinomial proportions that is based on the doubly truncated Poisson distribution and their method performs well when the cell counts are fairly equally dispersed over a large number of categories. In fact, the Sison and Glaz (1995) intervals appear to outperform other methods of simultaneous construction in terms of coverage probabilities and interval length in these situations. To make the method available to researchers, we have developed a SAS macro to construct the intervals proposed by Sison and Glaz (1995).
Jewish Persecutions and Weather Shocks: 1100–1800
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137319/1/ecoj12331_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137319/2/ecoj12331-sup-0001-AppendixA-D.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137319/3/ecoj12331.pd
A Field Comparison of Fresnel Zone and Ray-Based GPR Attenuation-Difference Tomography for Time-Lapse Imaging of Electrically Anomalous Tracer or Contaminant Plumes
Ground-penetrating radar (GPR) attenuation-difference tomography is a useful tool for imaging the migration of electrically anomalous tracer or contaminant plumes. Attenuation-difference tomography uses the difference in the trace amplitudes of tomographic data sets collected at different times to image the distribution of bulk-conductivity changes within the medium. The most common approach for computing the tomographic sensitivities uses ray theory, which is well understood and leads to efficient computations. However, ray theory requires the assumption that waves propagate at infinite frequency, and thus sensitivities are distributed along a line between the source and receiver. The infinite-frequency assumption in ray theory leads to a significant loss of resolution (both spatially and in terms of amplitude) of the recovered image. We use scattering theory to approximate the sensitivity of electromagnetic (EM) wave amplitude to changes in bulk conductivity within the medium. These sensitivities occupy the first Fresnel zone, account for the finite frequency nature of propagating EM waves, and are valid when velocity variations within the medium do not cause significant ray bending. We evaluate the scattering theory sensitivities by imaging a bromide tracer plume as it migrates through a coarse alluvial aquifer over two successive days. The scattering theory tomograms display a significant improvement in resolution over the ray-based counterparts, as shown by a direct comparison of the tomograms and also by a comparison of the vertical fluid conductivity distribution measured in a monitoring well, located within the tomographic plane. By improving resolution, the scattering theory sensitivities increase the utility of GPR attenuation- difference tomography for monitoring the movement of electrically anomalous plumes. In addition, the improved accuracy of information gathered through attenuation-difference tomography using scattering theory is a positive step toward future developments in using GPR data to help characterize the distribution of hydrogeologic propertie
Applied Remote Sensing Program (ARSP)
There are no author-identified significant results in this report
Hearing and dementia: from ears to brain
The association between hearing impairment and dementia has emerged as a major public health challenge, with significant opportunities for earlier diagnosis, treatment and prevention. However, the nature of this association has not been defined. We hear with
our brains, particularly within the complex soundscapes of everyday life: neurodegenerative pathologies target the auditory brain,
and are therefore predicted to damage hearing function early and profoundly. Here we present evidence for this proposition, based
on structural and functional features of auditory brain organization that confer vulnerability to neurodegeneration, the extensive,
reciprocal interplay between ‘peripheral’ and ‘central’ hearing dysfunction, and recently characterized auditory signatures of canonical neurodegenerative dementias (Alzheimer’s disease, Lewy body disease and frontotemporal dementia). Moving beyond any simple dichotomy of ear and brain, we argue for a reappraisal of the role of auditory cognitive dysfunction and the critical coupling of
brain to peripheral organs of hearing in the dementias. We call for a clinical assessment of real-world hearing in these diseases that
moves beyond pure tone perception to the development of novel auditory ‘cognitive stress tests’ and proximity markers for the
early diagnosis of dementia and management strategies that harness retained auditory plasticit
Borehole Radar Attenuation-Difference Tomography During the Tracer/Time-Lapse Test at the Boise Hydrogeophysical Research Site
A tracer test and time-lapse radar imaging experiment was conducted at the Boise Hydrogeophysical Research Site to investigate the utility of crosswell radar in imaging an electrically conductive tracer plume. A multilevel water sampling system down gradient from the tracer injection well and in the radar imaging plane was used to collect detailed, 1-dimensional, fluid electrical conductivity data during the tracer test. We compare the spatial and temporal position and concentration variations of the plume as indicated by the fluid conductivity data to those suggested by radar level run attenuation differences, shot-receiver attenuation difference crossplots, and an attenuation-difference tomogram. We find that attenuation differences generally correlate well with changes in fluid conductivity. Where correlations are not so strong, the discrepancies can be explained by the difference in support volumes for the radar and chemistry measurements, and also by regularization of the radar tomogram. Our results indicate that crosswell radar imaging coupled with hydrologic tracer testing can provide useful information about subsurface fluid flow and mass transport in complex fluvial aquifers
From the Persecuting to the Protective State? Jewish Expulsions and Weather Shocks from 1100 to 1800
What factors caused the persecution of minorities in medieval and early modern Europe? We build a model that predicts that minority communities were more likely to be expropriated in the wake of negative income shocks. We then use panel data consisting of 785 city-level expulsions of Jews from 933 European cities between 1100 and 1800 to test the implications of the model. We use the variation in city-level temperature to test whether expulsions were associated with colder growing seasons. We find that a one standard deviation decrease in average growing season temperature in the fifteenth and sixteenth centuries was associated with a one to two percentage point increase in the likelihood that a Jewish community would be expelled. Drawing on our model and on additional historical evidence we argue that the rise of state capacity was one reason why this relationship between negative income shocks and expulsions weakened after 1600
From the Persecuting to the Protective State? Jewish Expulsions and Weather Shocks from 1100 to 1800
What factors caused the persecution of minorities in medieval and early modern Europe? We build a model that predicts that minority communities were more likely to be expropriated in the wake of negative income shocks. We then use panel data consisting of 785 city-level expulsions of Jews from 933 European cities between 1100 and 1800 to test the implications of the model. We use the variation in city-level temperature to test whether expulsions were associated with colder growing seasons. We find that a one standard deviation decrease in average growing season temperature in the fifteenth and sixteenth centuries was associated with a one to two percentage point increase in the likelihood that a Jewish community would be expelled. Drawing on our model and on additional historical evidence we argue that the rise of state capacity was one reason why this relationship between negative income shocks and expulsions weakened after 1600
Universal screening of Tanzanian HIV-infected adult inpatients with the serum cryptococcal antigen to improve diagnosis and reduce mortality: an operational study
Cryptococcal meningitis is a leading cause of death among HIV-infected individuals in sub-Saharan Africa. Recent developments include the availability of intravenous fluconazole, cryptococcal antigen assays and new data to support fluconazole pre-emptive treatment. In this study, we describe the impact of screening HIV-positive adult inpatients with serum cryptococcal antigen (CRAG) at a Tanzanian referral hospital. All adults admitted to the medical ward of Bugando Medical Centre are counseled and tested for HIV. In this prospective cohort study, we consecutively enrolled HIV-positive patients admitted between September 2009 and January 2010. All patients were interviewed, examined and screened with serum CRAG. Patients with positive serum CRAG or signs of meningitis underwent lumbar puncture. Patients were managed according to standard World Health Organization treatment guidelines. Discharge diagnoses and in-hospital mortality were recorded.\ud
Of 333 HIV-infected adults enrolled in our study, 15 (4.4%) had confirmed cryptococcal meningitis and 10 of these 15 (66%) died. All patients with cryptococcal meningitis had at least two of four classic symptoms and signs of meningitis: fever, headache, neck stiffness and altered mental status. Cryptococcal meningitis accounted for a quarter of all in-hospital deaths. Despite screening of all HIV-positive adult inpatients with the serum CRAG at the time of admission and prompt treatment with high-dose intravenous fluconazole in those with confirmed cryptococcal meningitis, the in-hospital mortality rate remained unacceptably high. Improved strategies for earlier diagnosis and treatment of HIV, implementation of fluconazole pre-emptive treatment for high-risk patients and acquisition of better resources for treatment of cryptococcal meningitis are needed
FAD binding, cobinamide binding and active site communication in the corrin reductase (CobR)
Adenosylcobalamin, the coenzyme form of vitamin B12, is one Nature's most complex coenzyme whose de novo biogenesis proceeds along either an anaerobic or aerobic metabolic pathway. The aerobic synthesis involves reduction of the centrally chelated cobalt metal ion of the corrin ring from Co(II) to Co(I) before adenosylation can take place. A corrin reductase (CobR) enzyme has been identified as the likely agent to catalyse this reduction of the metal ion. Herein, we reveal how Brucella melitensis CobR binds its coenzyme FAD (flavin dinucleotide) and we also show that the enzyme can bind a corrin substrate consistent with its role in reduction of the cobalt of the corrin ring. Stopped-flow kinetics and EPR reveal a mechanistic asymmetry in CobR dimer that provides a potential link between the two electron reduction by NADH to the single electron reduction of Co(II) to Co(I)
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