5,972 research outputs found

    The Auslander-Gorenstein property for Z-algebras

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    We provide a framework for part of the homological theory of Z-algebras and their generalizations, directed towards analogues of the Auslander-Gorenstein condition and the associated double Ext spectral sequence that are useful for enveloping algebras of Lie algebras and related rings. As an application, we prove the equidimensionality of the characteristic variety of an irreducible representation of the Z-algebra, and for related representations over quantum symplectic resolutions. In the special case of Cherednik algebras of type A, this answers a question raised by the authors.Comment: 31 page

    Comment on "Density Functional Simulation of a Breaking Nanowire"

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    In a recent Letter, Nakamura et al. [Phys. Rev. Lett. 82, 1538 (1999)] described first principles calculations for a breaking Na nanocontact. Their system consists of a periodic one-dimensional array of supercells, each of which contains 39 Na atoms, originally forming a straight, crystalline wire with a length of 6 atoms. The system is elongated by increasing the length of the unit cell. At each step, the atomic configuration is relaxed to a new local equilibrium, and the tensile force is evaluated from the change of the total energy with elongation. Aside from a discontinuity of the force occuring at the transition from a crytalline to an amorphous configuration during the early stages of elongation, they were unable to identify any simple correlations between the force and the number of electronic modes transmitted through the contact. An important question is whether their model is realistic, i.e., whether it can be compared to experimental results obtained for a single nanocontact between two macroscopic pieces of metal. In this Comment, we demonstrate that with such a small unit cell, the interference effects between neighboring contacts are of the same size as the force oscillations in a single nanocontact.Comment: 1 pag

    Employee Retention in Insurance Claim Adjusting: A Growing Problem with Few Solutions

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    This paper defines and documents the growing problem of employee turnover and the failure by insurance and by claim adjusting companies to increase employee retention. According to industry sources, insurance is in the industry with the highest rate of employee turnover. This comes at a significant financial loss and what is called “contagious dissatisfaction,” resulting in a toxic work culture. Further, the growing problem of employee turnover in insurance claim adjusting comes at a time when nearly half of employee talent recruiters report that it is getting harder to find skilled candidates in a number of functional areas, including claims. The problem can be traced to promises upon hire which do not match the reality of the working position, overworking claim adjusters in general, hiring claim adjusters as managers rather than managers of people who know claims, as well as a failure to mitigate the “aggregate of incoming,” which is defined in this paper as the total amount of daily emails, letters, attachments, calls, and all other claim-related items adjusters receive. If companies address these areas and work with adjusters to manage a reasonable claim pending, they will experience less turnover, higher employee retention, decrease financial losses, and improve their work culture

    Correlated charge polarization in a chain of coupled quantum dots

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    Coherent charge transfer in a linear array of tunnel-coupled quantum dots, electrostatically coupled to external gates, is investigated using the Bethe ansatz for a symmetrically biased Hubbard chain. Charge polarization in this correlated system is shown to proceed via two distinct processes: formation of bound states in the metallic phase, and charge transfer processes corresponding to a superposition of antibound states at opposite ends of the chain in the Mott-insulating phase. The polarizability in the insulating phase of the chain exhibits a universal scaling behavior, while the polarization charge in the metallic phase of the model is shown to be quantized in units of e/2e/2.Comment: 9 pages, 3 figures, 1 tabl

    The Seminary of Treguier in the Seventeenth Century

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    The Congregation directed the seminary of Tréguier in Brittany from its beginning. The seminary was chiefly concerned with the proper formation of the local clergy, although it also gave numerous retreats and missions. The details of the seminary’s establishment, finances, demographics, community life, and accomplishments are reported as far as is possible from the records that remain. The seminary’s many difficulties are recounted, which make its successes all the more remarkable

    Predicting gene expression in the human malaria parasite Plasmodium falciparum using histone modification, nucleosome positioning, and 3D localization features.

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    Empirical evidence suggests that the malaria parasite Plasmodium falciparum employs a broad range of mechanisms to regulate gene transcription throughout the organism's complex life cycle. To better understand this regulatory machinery, we assembled a rich collection of genomic and epigenomic data sets, including information about transcription factor (TF) binding motifs, patterns of covalent histone modifications, nucleosome occupancy, GC content, and global 3D genome architecture. We used these data to train machine learning models to discriminate between high-expression and low-expression genes, focusing on three distinct stages of the red blood cell phase of the Plasmodium life cycle. Our results highlight the importance of histone modifications and 3D chromatin architecture in Plasmodium transcriptional regulation and suggest that AP2 transcription factors may play a limited regulatory role, perhaps operating in conjunction with epigenetic factors

    Many-body theory of electronic transport in single-molecule heterojunctions

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    A many-body theory of molecular junction transport based on nonequilibrium Green's functions is developed, which treats coherent quantum effects and Coulomb interactions on an equal footing. The central quantity of the many-body theory is the Coulomb self-energy matrix ΣC\Sigma_{\rm C} of the junction. ΣC\Sigma_{\rm C} is evaluated exactly in the sequential tunneling limit, and the correction due to finite tunneling width is evaluated self-consistently using a conserving approximation based on diagrammatic perturbation theory on the Keldysh contour. Our approach reproduces the key features of both the Coulomb blockade and coherent transport regimes simultaneously in a single unified transport theory. As a first application of our theory, we have calculated the thermoelectric power and differential conductance spectrum of a benzenedithiol-gold junction using a semi-empirical π\pi-electron Hamiltonian that accurately describes the full spectrum of electronic excitations of the molecule up to 8--10eV.Comment: 13 pages, 7 figure

    A review of the characteristics and treatment progress of 45 pregnant opiate addicts attending the Irish National Drug Advisory and Treatment Centre over a two year period.

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    The increase in the number of patients presenting to the National Drug Advisory and Treatment Centre addicted to opiates has been accompanied by an increase in the number of pregnant opiate addicts attending for treatment. Studies published in January 1982 referred to the emergence of maternal addiction as a serious problem in Ireland. Since then the escalation of this specific problem has continued and a programme designed to meet the needs of the pregnant addict was initiated at the clinic. This paper reviews the characteristics and treatment progress of 45 opiate addicts who were referred to the clinic over a two year period
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