1,788 research outputs found

    Reduction of Some 2-Thiazoline Benzamide and Carbamate Derivatives with Lithium Aluminum Hydride

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    This paper r eports the reduction with litMum aluminum hydride of 2-benzamido-5-methyl-2-thiazoline (Va) and 2-benzamido- 5,5-dimethyl-2-thiazo1\u27ine (Vb) to give the corresponding 2-benzyfamino-2-thiazolines (Via, b), and of ethyl N-(5-methyl-2- -thiazoline-2-yl)-carbamate (Ila) and ethyl N-(5,5-dimethyl-2-thiazoline- 2-yl)-carbamate (Ilb) to give the corresponding 2-methylamino- 2-thiazolines (Illa, b). No evidence of ring reduction or cleavage was observed either at room temperature or in refluxing ether or tetrahydrofuran. The structure of the products was confirmed by independent syntheses. Characteristic infrared bands ar e described

    Learning to mentalize: a mediational approach for caregivers and therapists

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    Mentalization-based therapies (MBTs) are rigorous, theoretically grounded, and evidence-based interventions. However, dissemination of this psychodynamically informed intervention lags behind that of more skills-based therapies because of a lack of concrete operationalization of its key components. In this proof-of-concept paper, we describe how the learning (mediational) components of an educational intervention, the Mediational Intervention for Sensitizing Caregivers (MISC), can operationalize key components of MBTs in behaviorally anchored ways. We suggest that the process of the recovery of mentalizing can be operationalized through five learning components: focusing, affecting, expanding, rewarding, and regulating. In operationalizing the process of rebuilding mentalizing using these observable, behaviorally anchored concepts focusing on creating epistemic trust, we hope to increase the accessibility of MBTs to a wider audience

    Power-Based Droop Control in DC Microgrids Enabling Seamless Disconnection From Upstream Grids

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    This paper proposes a local power-based droop controller for distributed energy resource converters in dc microgrids that are connected to upstream grids by grid-interface converters. During normal operation, the grid-interface converter imposes the microgrid bus voltage, and the proposed controller allows power flow regulation at distributed energy resource converters\u2019 output. On the other hand, during abnormal operation of the grid-interface converter (e.g., due to faults in the upstream grid), the proposed controller allows bus voltage regulation by droop control. Notably, the controller can autonomously convert from power flow control to droop control, without any need of bus voltage variation detection schemes or communication with other microgrid components, which enables seamless transitions between these two modes of operation. Considering distributed energy resource converters employing the power-based droop control, the operation modes of a single converter and of the whole microgrid are defined and investigated herein. The controller design is also introduced. Furthermore, the power sharing performance of this control approach is analyzed and compared with that of classical droop control. The experimental results from a laboratory-scale dc microgrid prototype are reported to show the final performances of the proposed power-based droop control

    Glassy Random Matrix Models

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    This paper discusses Random Matrix Models which exhibit the unusual phenomena of having multiple solutions at the same point in phase space. These matrix models have gaps in their spectrum or density of eigenvalues. The free energy and certain correlation functions of these models show differences for the different solutions. Here I present evidence for the presence of multiple solutions both analytically and numerically. As an example I discuss the double well matrix model with potential V(M)=μ2M2+g4M4V(M)= -{\mu \over 2}M^2+{g \over 4}M^4 where MM is a random N×NN\times N matrix (the M4M^4 matrix model) as well as the Gaussian Penner model with V(M)=μ2M2tlnMV(M)={\mu\over 2}M^2-t \ln M. First I study what these multiple solutions are in the large NN limit using the recurrence coefficient of the orthogonal polynomials. Second I discuss these solutions at the non-perturbative level to bring out some differences between the multiple solutions. I also present the two-point density-density correlation functions which further characterizes these models in a new university class. A motivation for this work is that variants of these models have been conjectured to be models of certain structural glasses in the high temperature phase.Comment: 25 pages, Latex, 7 Figures, to appear in PR

    A unified fluctuation formula for one-cut β\beta-ensembles of random matrices

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    Using a Coulomb gas approach, we compute the generating function of the covariances of power traces for one-cut β\beta-ensembles of random matrices in the limit of large matrix size. This formula depends only on the support of the spectral density, and is therefore universal for a large class of models. This allows us to derive a closed-form expression for the limiting covariances of an arbitrary one-cut β\beta-ensemble. As particular cases of the main result we consider the classical β\beta-Gaussian, β\beta-Wishart and β\beta-Jacobi ensembles, for which we derive previously available results as well as new ones within a unified simple framework. We also discuss the connections between the problem of trace fluctuations for the Gaussian Unitary Ensemble and the enumeration of planar maps.Comment: 16 pages, 4 figures, 3 tables. Revised version where references have been added and typos correcte

    Ice-lens formation and geometrical supercooling in soils and other colloidal materials

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    We present a new, physically-intuitive model of ice-lens formation and growth during the freezing of soils and other dense, particulate suspensions. Motivated by experimental evidence, we consider the growth of an ice-filled crack in a freezing soil. At low temperatures, ice in the crack exerts large pressures on the crack walls that will eventually cause the crack to split open. We show that the crack will then propagate across the soil to form a new lens. The process is controlled by two factors: the cohesion of the soil, and the geometrical supercooling of the water in the soil; a new concept introduced to measure the energy available to form a new ice lens. When the supercooling exceeds a critical amount (proportional to the cohesive strength of the soil) a new ice lens forms. This condition for ice-lens formation and growth does not appeal to any ad hoc, empirical assumptions, and explains how periodic ice lenses can form with or without the presence of a frozen fringe. The proposed mechanism is in good agreement with experiments, in particular explaining ice-lens pattern formation, and surges in heave rate associated with the growth of new lenses. Importantly for systems with no frozen fringe, ice-lens formation and frost heave can be predicted given only the unfrozen properties of the soil. We use our theory to estimate ice-lens growth temperatures obtaining quantitative agreement with the limited experimental data that is currently available. Finally we suggest experiments that might be performed in order to verify this theory in more detail. The theory is generalizable to complex natural-soil scenarios, and should therefore be useful in the prediction of macroscopic frost heave rates.Comment: Submitted to PR
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