6,179 research outputs found

    On geometric aspects of diffuse groups

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    Bowditch introduced the notion of diffuse groups as a geometric variation of the unique product property. We elaborate on various examples and non-examples, keeping the geometric point of view from Bowditch's paper. In particular, we discuss fundamental groups of flat and hyperbolic manifolds. The appendix settles an open question by providing an example of a group which is diffuse but not left-orderable.Comment: 37 pages, main text by Kionke and Raimbault, appendix by Dunfield. v2 : updated ancillary files and added url to the reference

    Check cashers: moving from the fringes to the financial mainstream

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    Once relegated to the margins of the financial services industry, check cashing outlets (CCO's) are now more visible parts of the urban landscape. Check cashers offer convenient check clearing and bill payment services, mostly tailored to meet the needs of the "unbanked" in low-and moderate income communities. The industry has grown dramatically over the years and is generating new products and services to meet the needs of its niche clientele. While some argue that check cashers are offering marginalized lower income Americans more responsive products than those available from banks, consumer advocates and community groups disagree. They argue that CCO customers pay too much for basic payment services, and that a reliance on check cashers keeps these lower-income individuals form being integrated into the financial mainstream. Lesly Jean-Paul and Luxman Nathan examine industry trends and the reach of check cashers here in New England.Checks ; Unbanked

    Music enrichment for gifted children in the first grade

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    Thesis (Ed.M.)--Boston Universit

    The Automobile Exception: A Contradiction in Fourth Amendment Principles

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    This Comment discusses the automobile exception to the Fourth Amendment warrant requirement. After reviewing the historical development of the exception, the author suggests that warrantless searches of vehicles are inconsistent with the values underlying the Fourth Amendment. The author concludes that, in the absence of a true exigency, warrantless searches of a vehicle should be prohibited, and that vehicles should instead be temporarily seized until a search warrant is secured

    Early contingentnegative variation of the EEG and attentional flexibility are reduced in hypotension

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    This study explored the question as to whether hypotension is related to decreased attentional performance and reduced cortical activation. A total of 50 females aged 19 44 years participated in the study. Attentional performance was assessed using three subtests of the Attentional and Cognitive Efficiency (ACE) battery. Contingent negative variation (CNV) as a measure of cortical activation was registered during a constant fore-period reaction time paradigm: two conditions were defined using tones as S1 (80 or 60 dB) and S2 (70 dB). The following results were obtained. Hypotensive patients performed significantly more poorly on one subtest of the ACE, which indicates a reduced speed for switching from a routine to a controlled response (quantifying attentional flexibility). They also had longer reaction times and revealed a significantly smaller amplitude of the early CNV component. In addition, a significant correlation was observed between systolic blood pressure and the amplitude of the early CNV component. The data support previous findings that hypotension can be related to lowered cortical activation and indicate that specific aspects of attentional performance might be negatively affected by hypotension

    Quadratic Hamiltonians in Fermionic Fock Spaces

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    Quadratic Hamiltonians are important in quantum field theory and quantum statistical mechanics. Their general studies, which go back to the sixties, are relatively incomplete for the fermionic case studied here. Following Berezin, they are quadratic in the fermionic field and in this way well-defined self-adjoint operators acting on the fermionic Fock space. We analyze their diagonalization by applying a novel elliptic operator-valued differential equations studied in a companion paper. This allows for their (N\mathrm{N}-) diagonalization under much weaker assumptions than before. Last but not least, in 1994 Bach, Lieb and Solovej defined them to be generators of strongly continuous unitary groups of Bogoliubov transformations. This is shown to be an equivalent definition, as soon as the vacuum state belongs to the domain of definition of these Hamiltonians. This second outcome is demonstrated to be reminiscent to the celebrated Shale-Stinespring condition on Bogoliubov transformations.Comment: 58 page
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