545 research outputs found

    Social Work Perceptions of Job Satisfaction in Host and Primary Settings: A Comparative Analysis

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    Job satisfaction can have personal and professional effects on social workers as well as the quality of service provided to clients. Structural variables such as supervision or role ambiguity may effect job satisfaction, but the intensity to which it effects the social worker may be different from setting to setting. The purpose of this research is to demonstrate the contribution of selected factors associated with job satisfaction in two different settings. The research design for this exploratory study, is a cross-sectional mailed survey. A random sample of 75 social workers in host settings and primary settings were sent surveys. A comparative analysis of the data was completed utilizing non-parametric statistics. The majority of social workers in both settings were satisfied with their job, however, specific factors were found to effect job satisfaction differently in host and primary settings

    The effect of Fermi surface curvature on low-energy properties of fermions with singular interactions

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    We discuss the effect of Fermi surface curvature on long-distance/time asymptotic behaviors of two-dimensional fermions interacting via a gapless mode described by an effective gauge field-like propagator. By comparing the predictions based on the idea of multi-dimensional bosonization with those of the strong- coupling Eliashberg approach, we demonstrate that an agreement between the two requires a further extension of the former technique.Comment: Latex, 4+ pages. Phys. Rev. Lett., to appea

    Monitoring the Petermann Ice Island with TanDEM-X

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    This paper presents the processing of TanDEM-X acquisitions for the monitoring of the topography of the Petermann ice island. In this particular case the area under study is continuously moving and the acquisition geometry is changing, so the processing of the iceberg’s DEMs is challenging and additional effects are to be considered. The SAR processing chain used is presented and the results obtained summarized, showing the effects and limitations observed during the process

    Hybrid Amperometric and Potentiometric Sensing Based on a CMOS ISFET Array

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    Potentiometry and amperometry are some of the most important techniques for electroanalytical applications. Integrating these two techniques on a single chip using CMOS technology paves the way for more analysis and measurement of chemical solutions. In this paper, we describe the integration of electrode transducers (amperometry) on an ion imager based on an ISFET array (potentiometry). In particular, this integration enables the spatial representation of the potential distribution of active electrodes in a chemical solution under investigation

    A 16 x 16 CMOS amperometric microelectrode array for simultaneous electrochemical measurements

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    There is a requirement for an electrochemical sensor technology capable of making multivariate measurements in environmental, healthcare, and manufacturing applications. Here, we present a new device that is highly parallelized with an excellent bandwidth. For the first time, electrochemical cross-talk for a chip-based sensor is defined and characterized. The new CMOS electrochemical sensor chip is capable of simultaneously taking multiple, independent electroanalytical measurements. The chip is structured as an electrochemical cell microarray, comprised of a microelectrode array connected to embedded self-contained potentiostats. Speed and sensitivity are essential in dynamic variable electrochemical systems. Owing to the parallel function of the system, rapid data collection is possible while maintaining an appropriately low-scan rate. By performing multiple, simultaneous cyclic voltammetry scans in each of the electrochemical cells on the chip surface, we are able to show (with a cell-to-cell pitch of 456 ÎĽm) that the signal cross-talk is only 12% between nearest neighbors in a ferrocene rich solution. The system opens up the possibility to use multiple independently controlled electrochemical sensors on a single chip for applications in DNA sensing, medical diagnostics, environmental sensing, the food industry, neuronal sensing, and drug discovery

    Composite SUVR: a new method for boosting Alzheimer's disease monitoring and diagnostic performance, applied to tau PET

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    Background: Abnormal brain tau protein accumulation is strongly linked to multiple neurodegenerative disorders. Currently, brain tau pathology is quantified in vivo using tau PET by calculating the Standardized Uptake Value Ratio (SUVR) of target and reference regions of interest (ROIs). Recent work (Schwarz et al., 2021) in Alzheimer’s Disease (AD) explored various target and reference ROIs to report performance of SUVR as a biomarker for diagnosis, disease monitoring, and clinical trial efficacy/eligibility (sample size estimate, SSE). Here we introduce a new method and biomarker: Composite SUVR (CUVR). / Methods: We analyzed longitudinal SUV data from ADNI in the available 103 participants having three or more tau PET scans ([18F]AV-1451): 58 cognitively normal (CN); 21 mild cognitive impairment; 24 probable AD. In the spirit of SUVR and statistical ROIs (Chen, et al., NeuroImage 2010), we calculate CUVR as the SUV ratio of two composite regions. Our novel method is that the composite regions are determined by a genetic algorithm that searches the possible 3^96 combinations of regions from FreeSurfer’s default atlas. We compare performance of SUVR with CUVR. Performance metrics follow Schwarz et al.: a linear mixed-effects model quantifies longitudinal group separation by tau accumulation rate (t statistic between fixed effects for CN and AD) and longitudinal precision (model residuals’ standard deviation). CUVR and SUVR values were log-transformed before model fitting. We calculated SSE for a hypothetical clinical trial designed for 80% power to reduce tau PET accumulation by 20% (vs. placebo) in non-CN individuals. / Results: Our method identified a CUVR biomarker involving 60 regions. Figure-1 shows the vast performance improvement of CUVR versus the best-performing SUVR (inferior-temporal target; eroded subcortical white matter reference). Group separation improved by 2.9x (t = 9.57 vs 3.32); longitudinal precision by 6.5x (residual std = 0.331% vs 2.14%); and CUVR required a smaller sample size by 3.9x (83 vs 318). / Conclusions: Our simple data-driven approach discovered a new tau PET biomarker called CUVR. Experimental results show state-of-the-art longitudinal group separation, longitudinal precision, and clinical trial enrichment. The remarkable performance improvements provide compelling evidence for using CUVR for both eligibility and efficacy in Alzheimer’s disease clinical trials, particularly of anti-tau therapies

    Untersuchung von Veränderungen cerebraler Metaboliten bei depressiven Patienten im Laufe einer EKT-Serie mittels 1 H-Magnetresonanzspektroskopie

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    14 Patienten mit Indikation zur Elektrokrampftherapie (EKT) bei einer schweren depressiven Episode wurden vor EKT, nach 6 EKT und am Ende der EKT-Serie untersucht. Mittels Magnetresonanzspektroskopie wurde N-Acetyl-Aspartat, Cholin, Creatin, Glutamin/Glutamat (Glx) und myo-Inositol in Hippocampus und linkem Cingulum gemessen. Erfolgreiche EKT führt im Cingulum zu einem Anstieg von Cholin, erklärbar durch vermehrten Membranumsatz. Die Zunahme von Creatin im Hippocampus zeigt einen Zusammenhang zwischen Stimmung und Energieversorgung. Der gemessene Glx-Anstieg könnte mitverantwortlich für die Gedächtnisstörung nach EKT sein. Die vorliegende Arbeit zeigt, dass im Hippocampus und Cingulum metabolische Veränderungen unter EKT auftreten, die sowohl klinische Effizienz als auch Nebenwirkungen erklären können. Weitere Untersuchungen von Cholin, Creatin und Glx an großen Patientenzahlen können zum tieferen Verständnis der depressiven Störungen sowie der Wirkungsweise der EKT beitragen

    An experimental approach for investigating many-body phenomena in Rydberg-interacting quantum systems

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    Recent developments in the study of ultracold Rydberg gases demand an advanced level of experimental sophistication, in which high atomic and optical densities must be combined with excellent control of external fields and sensitive Rydberg atom detection. We describe a tailored experimental system used to produce and study Rydberg-interacting atoms excited from dense ultracold atomic gases. The experiment has been optimized for fast duty cycles using a high flux cold atom source and a three beam optical dipole trap. The latter enables tuning of the atomic density and temperature over several orders of magnitude, all the way to the Bose-Einstein condensation transition. An electrode structure surrounding the atoms allows for precise control over electric fields and single-particle sensitive field ionization detection of Rydberg atoms. We review two experiments which highlight the influence of strong Rydberg--Rydberg interactions on different many-body systems. First, the Rydberg blockade effect is used to pre-structure an atomic gas prior to its spontaneous evolution into an ultracold plasma. Second, hybrid states of photons and atoms called dark-state polaritons are studied. By looking at the statistical distribution of Rydberg excited atoms we reveal correlations between dark-state polaritons. These experiments will ultimately provide a deeper understanding of many-body phenomena in strongly-interacting regimes, including the study of strongly-coupled plasmas and interfaces between atoms and light at the quantum level.Comment: 14 pages, 11 figures; submitted to a special issue of 'Frontiers of Physics' dedicated to 'Quantum Foundation and Technology: Frontiers and Future

    Dynamic scaling in the vicinity of the Luttinger liquid fixed point

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    We calculate the single-particle spectral function A (k, omega) of a one-dimensional Luttinger liquid by means of a functional renormalization group (RG) approach. Given an infrared energy cutoff Lambda = Lambda_0 e^{- l}, our approach yields the spectral function in the scaling form, A_{\Lambda} (k_F + p, omega) = tau Z_l tilde{A}_l (p xi, omega tau), where k_F is the Fermi momentum, Z_l is the wave-function renormalization factor, tau = 1 / \Lambda is the time scale and xi = v_F / \Lambda is the length scale associated with Lambda. At the Luttinger liquid fixed point (l rightarrow infty) our RG result for A (k, omega) exhibits the correct anomalous scaling properties, and for k = \pm k_F agrees exactly with the well-known bosonization result at weak coupling. Our calculation demonstrates that the field rescaling is essential for obtaining the crossover from Fermi liquid behavior to Luttinger liquid behavior from a truncation of the hierarchy of exact RG flow equations as the infrared cutoff is reduced.Comment: 15 pages, 5 figure

    Radiative Transfer in Obliquely Illuminated Accretion Disks

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    The illumination of an accretion disk around a black hole or neutron star by the central compact object or the disk itself often determines its spectrum, stability, and dynamics. The transport of radiation within the disk is in general a multi-dimensional, non-axisymmetric problem, which is challenging to solve. Here, I present a method of decomposing the radiative transfer equation that describes absorption, emission, and Compton scattering in an obliquely illuminated disk into a set of four one-dimensional transfer equations. I show that the exact calculation of the ionization balance and radiation heating of the accretion disk requires the solution of only one of the one-dimensional equations, which can be solved using existing numerical methods. I present a variant of the Feautrier method for solving the full set of equations, which accounts for the fact that the scattering kernels in the individual transfer equations are not forward-backward symmetric. I then apply this method in calculating the albedo of a cold, geometrically thin accretion disk.Comment: 16 pages, 3 figures; to appear in The Astrophysical Journa
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