825 research outputs found

    Annual Report for Gravity Collection Lysimeter Monitoring in ERDF Cells 5, 6, 7, an 8, CY 2009

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    The purpose of this annual report is to evaluate the conditions and identify trends to develop Hanford Site specific data on the performance of the lysimeter systems related to the vadose zone monitoring and potential future use of lysimeter systems

    Entropy and the variational principle for actions of sofic groups

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    Recently Lewis Bowen introduced a notion of entropy for measure-preserving actions of a countable sofic group on a standard probability space admitting a generating partition with finite entropy. By applying an operator algebra perspective we develop a more general approach to sofic entropy which produces both measure and topological dynamical invariants, and we establish the variational principle in this context. In the case of residually finite groups we use the variational principle to compute the topological entropy of principal algebraic actions whose defining group ring element is invertible in the full group C*-algebra.Comment: 44 pages; minor changes; to appear in Invent. Mat

    The effect of age and font size on reading text on handheld computers

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    Though there have been many studies of computer based text reading, only a few have considered the small screens of handheld computers. This paper presents an investigation into the effect of varying font size between 2 and 16 point on reading text on a handheld computer. By using both older and younger participants the possible effects of age were examined. Reading speed and accuracy were measured and subjective views of participants recorded. Objective results showed that there was little difference in reading performance above 6 point, but subjective comments from participants showed a preference for sizes in the middle range. We therefore suggest, for reading tasks, that designers of interfaces for mobile computers provide fonts in the range of 8-12 point to maximize readability for the widest range of users

    Edge magnetoplasmons in periodically modulated structures

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    We present a microscopic treatment of edge magnetoplasmons (EMP's) within the random-phase approximation for strong magnetic fields, low temperatures, and filling factor ν=1(2)\nu =1(2), when a weak short-period superlattice potential is imposed along the Hall bar. The modulation potential modifies both the spatial structure and the dispersion relation of the fundamental EMP and leads to the appearance of a novel gapless mode of the fundamental EMP. For sufficiently weak modulation strengths the phase velocity of this novel mode is almost the same as the group velocity of the edge states but it should be quite smaller for stronger modulation. We discuss in detail the spatial structure of the charge density of the renormalized and the novel fundamental EMP's.Comment: 8 pages, 4 figure

    Transversity distributions in the nucleon in the large-N_c limit

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    We compute the quark and antiquark transversity distributions in the nucleon at a low normalization point of 600 MeV in the large-NcN_c limit, where the nucleon can be described as a soliton of an effective chiral theory (chiral quark-soliton model). The flavor-nonsinglet distributions, δu(x)δd(x)\delta u(x) - \delta d(x) and δuˉ(x)δdˉ(x)\delta\bar u(x) - \delta\bar d(x), appear in leading order of the 1/Nc1/N_c-expansion, while the flavor-singlet distributions, δu(x)+δd(x)\delta u(x) + \delta d(x) and δuˉ(x)+δdˉ(x)\delta\bar u(x) + \delta\bar d(x), are non-zero only in next-to-leading order. The transversity quark and antiquark distributions are found to be significantly different from the longitudinally polarized distributions Δu(x)±Δd(x)\Delta u (x) \pm \Delta d (x) and Δuˉ(x)±Δdˉ(x)\Delta\bar u (x) \pm \Delta\bar d (x), respectively, in contrast to the prediction of the naive non-relativistic quark model. We show that this affects the predictions for the spin asymmetries in Drell-Yan pair production in transversely polarized pp and ppbar collisions.Comment: 45 pages, 16 figure

    Nano-Immunodetection and Quantification of Mycobacteria in Metalworking Fluids

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    The accurate detection and enumeration of mycobacteria in metalworking fluids (MWFs) is imperative from an environmental protection and occupational health perspective. We report here on a comparison of the labeling efficiency of nano-immunomagnetic particles (NIMP) and free antibody (FAb) to detect mycobacteria in semisynthetic MWF by using both traditional visualization analysis and cluster analysis aided visualization analysis (CAAVA). The NIMP labeling method involved coating nanometer-scale magnetic particles with Protein A, and oriented conjugation of polyclonal antibodies specific to Mycobacterium spp. The FAb labeling method is modified from the traditional immunofluorescence (IF) method for more efficient detection of mycobacteria in a model MWF. The labeling efficiency of NIMP and FAb were 7.2 ± 4.6 and 16.3 ± 5.5%, and the specificity 85.0 ± 6.1 and 88.1 ± 10.5%, respectively, based on traditional visualization analysis. Based on CAAVA analysis, the labeling efficiency of NIMP and FAb increased to 12.4 ± 1.6 and 20.5 ± 3.9%, and the specificity to 97.8 ± 3.2 and 98.5 ± 2.5%, respectively. A linear relationship of FCM counts and seeded concentrations was observed over four orders of magnitude (R 2 ≤ 0.99) in pure and ternary cultures. The results strongly support the applicability of either FAb or NIMP coupled with CAAVA and flow cytometry for rapid detection and enumeration of mycobacteria in complex matrices.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63114/1/ees.2007.24.58.pd

    Low-field magnetoresistance in GaAs 2D holes

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    We report low-field magnetotransport data in two-dimensional hole systems in GaAs/AlGaAs heterostructures and quantum wells, in a large density range, 2.5×1010p4.0×10112.5 \times 10^{10} \leq p \leq 4.0 \times 10^{11} cm2^{-2}, with primary focus on samples grown on (311)A GaAs substrates. At high densities, p1×1011p \gtrsim 1 \times 10^{11} cm2^{-2}, we observe a remarkably strong positive magnetoresistance. It appears in samples with an anisotropic in-plane mobility and predominantly along the low-mobility direction, and is strongly dependent on the perpendicular electric field and the resulting spin-orbit interaction induced spin-subband population difference. A careful examination of the data reveals that the magnetoresistance must result from a combination of factors including the presence of two spin-subbands, a corrugated quantum well interface which leads to the mobility anisotropy, and possibly weak anti-localization. None of these factors can alone account for the observed positive magnetoresistance. We also present the evolution of the data with density: the magnitude of the positive magnetoresistance decreases with decreasing density until, at the lowest density studied (p=2.5×1010p = 2.5 \times 10^{10} cm2^{-2}), it vanishes and is replaced by a weak negative magnetoresistance.Comment: 8 pages, 8 figure

    Repeating the Errors of Our Parents? Family-of-Origin Spouse Violence and Observed Conflict Management in Engaged Couples

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    Based on a developmental social learning analysis, it was hypothesized that observing parental violence predisposes partners to difficulties in managing couple conflict. Seventy-one engaged couples were assessed on their observation of parental violence in their family of origin. All couples were videotaped discussing two areas of current relationship conflict, and their cognitions during the interactions were assessed using a video-mediated recall procedure. Couples in which the male partner reported observing parental violence (male-exposed couples) showed more negative affect and communication during conflict discussions than couples in which neither partner reported observing parental violence (unexposed couples). Couples in which only the female partner reported observing parental violence (female- exposed couples) did not differ from unexposed couples in their affect or behavior. Female-exposed couples reported more negative cognitions than unexposed couples, but male-exposed couples did not differ from unexposed couples in their reported cognitions

    Self-consistent quantal treatment of decay rates within the perturbed static path approximation

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    The framework of the Perturbed Static Path Approximation (PSPA) is used to calculate the partition function of a finite Fermi system from a Hamiltonian with a separable two body interaction. Therein, the collective degree of freedom is introduced in self-consistent fashion through a Hubbard-Stratonovich transformation. In this way all transport coefficients which dominate the decay of a meta-stable system are defined and calculated microscopically. Otherwise the same formalism is applied as in the Caldeira-Leggett model to deduce the decay rate from the free energy above the so called crossover temperature T0T_0.Comment: 17 pages, LaTex, no figures; final version, accepted for publication in PRE; e-mail: [email protected]

    The Intentional Use of Service Recovery Strategies to Influence Consumer Emotion, Cognition and Behaviour

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    Service recovery strategies have been identified as a critical factor in the success of. service organizations. This study develops a conceptual frame work to investigate how specific service recovery strategies influence the emotional, cognitive and negative behavioural responses of . consumers., as well as how emotion and cognition influence negative behavior. Understanding the impact of specific service recovery strategies will allow service providers' to more deliberately and intentionally engage in strategies that result in positive organizational outcomes. This study was conducted using a 2 x 2 between-subjects quasi-experimental design. The results suggest that service recovery has a significant impact on emotion, cognition and negative behavior. Similarly, satisfaction, negative emotion and positive emotion all influence negative behavior but distributive justice has no effect
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