1,625 research outputs found

    Nutrient Geochemistry in North Central Ohio Lakes

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    Eight lakes in north central Ohio have been sampled to review their nutrient chemistry. Analysis was also done to compare the variation in nutrient concentration at primary locations of recharge and discharge. Five of the lakes have primary inlet and outlet stations which have also been sampled. The three reservoirs only have lake sampling measurements. The samples were collected starting in December of 2010 and continued through September of 2012. The lakes would be classified as small and the largest of them is 1350 acres. All of the water samples collected were run through a Skalar nutrient analyzer and tested for PO43- , NH4- , and NO3-+NO2-. Once the data was compiled, graphs showed all eight lakes/reservoirs with the variations in chemistry of the three nutrients. Based on the average nutrient concentrations of the lakes studied, they are considered to be in poor biological condition. The data also shows that the lakes are acting as a sink for nitrogen based on the variation of inlet and outlet concentrations. Cyanobacteria decomposition was an important factor in the concentration of ammonium concentrations at various locations sampled in the lakes.No embarg

    Electron-magnon coupling and nonlinear tunneling transport in magnetic nanoparticles

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    We present a theory of single-electron tunneling transport through a ferromagnetic nanoparticle in which particle-hole excitations are coupled to spin collective modes. The model employed to describe the interaction between quasiparticles and collective excitations captures the salient features of a recent microscopic study. Our analysis of nonlinear quantum transport in the regime of weak coupling to the external electrodes is based on a rate-equation formalism for the nonequilibrium occupation probability of the nanoparticle many-body states. For strong electron-boson coupling, we find that the tunneling conductance as a function of bias voltage is characterized by a large and dense set of resonances. Their magnetic field dependence in the large-field regime is linear, with slopes of the same sign. Both features are in agreement with recent tunneling experiments.Comment: 4 pages, 2 figure

    Large Magnetoresistance in Co/Ni/Co Ferromagnetic Single Electron Transistors

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    We report on magnetotransport investigations of nano-scaled ferromagnetic Co/Ni/Co single electron transistors. As a result of reduced size, the devices exhibit single electron transistor characteristics at 4.2K. Magnetotransport measurements carried out at 1.8K reveal tunneling magnetoresistance (TMR) traces with negative coercive fields, which we interpret in terms of a switching mechanism driven by the shape anisotropy of the central wire-like Ni island. A large TMR of about 18% is observed within a finite source-drain bias regime. The TMR decreases rapidly with increasing bias, which we tentatively attribute to excitation of magnons in the central island.Comment: 12 pages (including 4 figures). Accepted for publishing on AP

    General method for extracting the quantum efficiency of dispersive qubit readout in circuit QED

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    We present and demonstrate a general three-step method for extracting the quantum efficiency of dispersive qubit readout in circuit QED. We use active depletion of post-measurement photons and optimal integration weight functions on two quadratures to maximize the signal-to-noise ratio of the non-steady-state homodyne measurement. We derive analytically and demonstrate experimentally that the method robustly extracts the quantum efficiency for arbitrary readout conditions in the linear regime. We use the proven method to optimally bias a Josephson traveling-wave parametric amplifier and to quantify different noise contributions in the readout amplification chain.Comment: 10 pages, 6 figure

    Theory of Tunneling Spectroscopy in a Mn12_{12} Single-Electron Transistor by Density-Functional Theory Methods

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    We consider tunneling transport through a Mn12_{12} molecular magnet using spin density functional theory. A tractable methodology for constructing many-body wavefunctions from Kohn-Sham orbitals allows for the determination of spin-dependent matrix elements for use in transport calculations. The tunneling conductance at finite bias is characterized by peaks representing transitions between spin multiplets, separated by an energy on the order of the magnetic anisotropy. The energy splitting of the spin multiplets and the spatial part of their many-body wave functions, describing the orbital degrees of freedom of the excess charge, strongly affect the electronic transport, and can lead to negative differential conductance.Comment: 4 pages, 3 figures, a revised version with minor change

    Phosphine Functionalization of GaAs(111)A Surfaces

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    Phosphorus-functionalized GaAs surfaces have been prepared by exposure of Cl-terminated GaAs(111)A surfaces to triethylphosphine (PEt3) or trichlorophosphine (PCl3), or by the direct functionalization of the native-oxide terminated GaAs(111)A surface with PCl3. The presence of phosphorus on each functionalized surface was confirmed by X-ray photoelectron spectroscopy. High-resolution, soft X-ray photoelectron spectroscopy was used to evaluate the As and Ga 3d regions of such surfaces. On PEt3 treated surfaces, the Ga 3d spectra exhibited a bulk Ga peak as well as peaks that were shifted to 0.35, 0.92 and 1.86 eV higher binding energy. These peaks were assigned to residual Cl-terminated Ga surface sites, surficial Ga2O and surficial Ga2O3, respectively. For PCl3-treated surfaces, the Ga 3d spectra displayed peaks ascribable to bulk Ga(As), Ga2O, and Ga2O3, as well as a peak shifted 0.30 eV to higher binding energy relative to the bulk signal. A peak corresponding to Ga(OH)3, observed on the Cl-terminated surface, was absent from all of the phosphine-functionalized surfaces. After reaction of the Cl-terminated GaAs(111)A surface with PCl3 or PEt3, the As 3d spectral region was free of As oxides and As0. Although native oxide-terminated GaAs surfaces were free of As oxides after reaction with PCl3, such surfaces contained detectable amounts of As0. Photoluminescence measurements indicted that phosphine-functionalized surfaces prepared from Cl-terminated GaAs(111)A surfaces had better electrical properties than the native-oxide capped GaAs(111)A surface, while the native-oxide covered surface treated with PCl3 showed no enhancement in PL intensity

    Building Community, Fostering Collaboration, and Engaging Bridge Program Students with a college’s historical archives

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    Similar to smaller archives, this college’s archives have not been traditionally accessible online. Two instructors sought to teach summer bridge program (Boot Camp) students basic archival practices and quantitatively measure their information literacy skills through using the Information Literacy Skills (ILA) and Students’ Perceptions of their Information Skills-Questionnaire (SPIL-Q) instruments (cite). Boot Camp students’ average perceived confidence with IL skills as assessed by the SPIL-Q instrument increased from 4.00 to 4.77 (+19.2%) on the post-training SPIL-Q. By adding the ILA and SPIL-Q instruments to the course curriculum, combined with end of course reflection questions, the instructors were able to quantitatively determine if the students’ comprehension of evaluating information improved after handling, processing, and digitizing primary source documents. This study demonstrates the opportunities for community building and collaboration afforded by archivists and librarians engaging faculty and students with primary source exploration through college archives

    Lipid Disturbances in Psoriasis: An Update

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    Psoriasis is a common disease with the population prevalence ranging from 2% to 3%. Its prevalence in the population is affected by genetic, environmental, viral, infectious, immunological, biochemical, endocrinological, and psychological factors, as well as alcohol and drug abuse. In the recent years, psoriasis has been recognised as a systemic disease associated with numerous multiorgan abnormalities and complications. Dyslipidemia is one of comorbidities in psoriatic patients. Lipid metabolism studies in psoriasis have been started at the beginning of the 20th century and are concentrated on skin surface lipids, stratum corneum lipids and epidermal phospholipids, serum lipids, dermal low-density lipoproteins in the psoriatic skin, lipid metabolism, oxidative stress and correlations between inflammatory parameters, lipid parameters and clinical symptoms of the disease. On the basis of the literature data, psoriasis can be described as an immunometabolic disease
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