27,480 research outputs found

    D-XY Critical Behavior in Cuprate Superconductors

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    We outline the universal and finite temperature critical properties of the 3D-XY model, extended to anisotropic extreme type-II superconductors, as well as the universal quantum critical properties in 2D. On this basis we review: (i) the mounting evidence for 3D-XY behavior in optimally doped cuprate superconductors and the 3D to 2D crossover in the underdoped regime; (ii) the finite size limitations imposed by inhomogeneities; (iii) the experimental evidence for a 2D-XY quantum critical point in the underdoped limit, where the superconductor to insulator transition occurs; (iv) the emerging implications and constraints for microscopic models.Comment: 5 pages, 6 figure

    Children’s episodic and generic reports of alleged abuse

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    With the present data, we explored the relations between the language of interviewer questions, children’s reports, and case and child characteristics in forensic interviews. Results clearly indicated that the type of questions posed by interviewers – either probing generic or episodic features of an event – was related to the specificity of information reported by children. Further, interviewers appeared to adjust their questioning strategies based on the frequency of the alleged abuse. Children alleging single instances of abuse were asked more episodic questions than those alleging multiple abuses. In contrast, children alleging multiple incidents of abuse were asked a greater proportion of generic questions. Given that investigators often seek forensically-relevant episodic information, it is recommended that training for investigators focus on recognition of prompt selection tendencies and developing strategies for posing non-suggestive, episodically focused questions

    Relationship between and implications of the isotope and pressure effects on transition temperature, penetration depths and conductivities

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    It is shown that the empirical relations between transition temperature, normal state conductivity linearly extrapolated to the value at the transition temperature, zero temperature penetration depths, etc., as observed in a rich variety of cuprate superconductors, are remarkably consistent with the universal critical properties of anisotropic systems which fall into the 3D-XY universality class and undergo a crossover to a quantum critical point in 2D. The variety includes n- and p-type cuprates, comprises the underdoped and overdoped regimes and the consistency extends up to six decades in the scaling variables. The resulting scaling relations for the oxygen isotope and hydrostatic pressure effects agree with the experimental data and reveal that these effects originate from local lattice distortions preserving the volume of the unit cell. These observations single out 3D and anisotropic microscopic models which incorporate local lattice distortions, fall in the experimentally accessible regime into the 3D-XY universality class, and incorporate the crossover to 2D quantum criticality where superconductivity disappears.Comment: 19 pages, 17 figure

    Soil P Status and Nitrogen Fixation on Organic Dairy Farms in Ontario and Nova Scotia

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    Legumes are a key source of nitrogen (N) in organic production systems. However, there is evidence that reduced inputs may be leading to deficient soil phosphorus (P) on some organic dairy farms (Roberts et. al. 2008). This may affect crop performance and N fixation in forage legumes. This study aims to gauge the relationship between soil P dynamics in organic dairy systems and legume biological nitrogen fixation (BNF). The study has two main sub-projects: 1. A field survey of soil-test P and legume forage productivity and N fixation on dairy farms in Ontario and Nova Scotia, Canada. 2. Growth chamber and greenhouse studies examining: a) The role of P nutrition in legume growth and N fixation, and b) The P-supplying power of composts, struvite, and a rock P source. Field data was commenced in the 2008 season, and was completed in 2009. Growth chamber and greenhouse studies were conducted in 2009. Analyses of 2009 samples are not complete at the report date

    Dimensional effects on magnetic properties of Fe-Si steels due to laser and mechanical cutting

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    Microstructural deterioration near the cut line and presence of residual stresses both affect the magnetic properties of cut parts. In this paper, the differences between microstructural deterioration resulting from mechanical and laser cutting as well as the sample size effects observed upon hysteresis will be discussed. It will be shown that the underlying mechanism for changes in magnetic properties due to mechanical cutting is distinct from that of laser cutting

    Correlation between microstructure, texture, and magnetic induction in nonoriented electrical steels

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    Although it is well known that the magnetic induction of electrical steels at a given applied field critically depends on the microstructure and on the present crystallographic texture, there is still no quantitative model to describe this relation in the whole range of inductions. In this paper, the existing different models for the dependence of B-8, B-25, and B-50 on the texture intensities will be evaluated in detail. Finally, a more general model is proposed for the dependence of the magnetic induction at a given applied field as a function of the mean grain size, a texture related parameter and the Si content of the material

    Strangeness in the Scalar Form Factor of the Nucleon

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    The scalar form factor of the nucleon and related physical quantities are investigated in the framework of the semibosonized SU(3) Nambu-Jona-Lasinio soliton model. We take into account the rotational 1/Nc1/N_c corrections and linear msm_s corrections. The strangeness content of the nucleon in the scalar form factor is discussed in detail. In particular, it is found that the msm_s corrections play an essential role of reducing the ⟨N∣sˉs∣N⟩\langle N | \bar{s} s | N \rangle arising from the leading order and rotational 1/Nc1/N_c contributions. We obtain the \sigma_{\pi N} (0)=40.80\;\mbox{MeV}, \Delta \sigma = \sigma_{\pi N} (2m^{2}_{\pi})-\sigma_{\pi N} (0) = 18.18\;\mbox{MeV} and \langle r^2\rangle^{S}_{N} = 1.50\;\mbox{fm}^2. The results are in a remarkable agreement with empirical data analyzed by Gasser, Leutwyler, and Sainio~\cite{gls}.Comment: 13 pages, RevTex is used. 3 figures as uufiles are include

    Experimental and analytical comparison of flowfields in a 110 N (25 lbf) H2/O2 rocket

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    A gaseous hydrogen/gaseous oxygen 110 N (25 lbf) rocket was examined through the RPLUS code using the full Navier-Stokes equations with finite rate chemistry. Performance tests were conducted on the rocket in an altitude test facility. Preliminary parametric analyses were performed for a range of mixture ratios and fuel film cooling pcts. It is shown that the computed values of specific impulse and characteristic exhaust velocity follow the trend of the experimental data. Specific impulse computed by the code is lower than the comparable test values by about two to three percent. The computed characteristic exhaust velocity values are lower than the comparable test values by three to four pct. Thrust coefficients computed by the code are found to be within two pct. of the measured values. It is concluded that the discrepancy between computed and experimental performance values could not be attributed to experimental uncertainty
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