3,972 research outputs found

    On sequence spaces for Fr\'echet frames

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    We analyze the construction of a sequence space Θ~\widetilde{\Theta}, resp. a sequence of sequence spaces, in order to have {gi}\{g_i\} as a Θ~\widetilde{\Theta}-frame or Banach frame for a Banach space XX, resp. pre-FF-frame or FF-frame for a Fr\'echet space XF=∩s∈N0XsX_F=\cap_{s\in {\mathbb N}_0} X_s, where {Xs}s∈N0\{X_s\}_{s\in {\mathbb N}_0} is a sequence of Banach spaces

    Funding Shortfall for Housing Vouchers Could Have Serious Health Consequences for Children

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    In the fourth brief in its Policy Action series, Children's HealthWatch finds that unaffordable housing endangers the health and development of young children. Due to a federal funding shortfall, state and local housing agencies will be forced to reduce or eliminate rental assitance to thousands of families starting this month. Voucher cuts will push more families into the ranks of the "hidden homeless" -- families that move frequently, crowd into apartments that are too small, or live doubled up with other households when they cannot find affordable housing. Children in hidden homeless families are at increased risk for poor health, nutrition, and growth, as well as developmental delays. Timely Congressional action to protect the Housing Choice Voucher Program will ensure that families have stable, affordable housing essential to children's health

    Invasive Pathogen Threatens Bird-Pine Mutualism: Implications for Sustaining a High-Elevation Ecosystem

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    Human-caused disruptions to seed-dispersal mutualisms increase the extinction risk for both plant and animal species. Large-seeded plants can be particularly vulnerable due to highly specialized dispersal systems and no compensatory regeneration mechanisms. Whitebark pine ( Pinus albicaulis), a keystone subalpine species, obligately depends upon the Clark\u27s Nutcracker (Nucifraga columbiana) for dispersal of its large, wingless seeds. Clark\u27s Nutcracker, a facultative mutualist with whitebark pine, is sensitive to rates of energy gain, and emigrates from subalpine forests during periods of cone shortages. The invasive fungal pathogen Cronartium ribicola, which causes white pine blister rust, reduces whitebark pine cone production by killing cone-bearing branches and trees. Mortality from blister rust reaches 90% or higher in some whitebark pine forests in the Northern Rocky Mountains, USA, and the rust now occurs nearly rangewide in whitebark pine. Our objectives were to identify the minimum level of cone production necessary to elicit seed dispersal by nutcrackers and to determine how cone production is influenced by forest structure and health. We quantified forest conditions and ecological interactions between nutcrackers and whitebark pine in three Rocky Mountain ecosystems that differ in levels of rust infection and mortality. Both the frequency of nutcracker occurrence and probability of seed dispersal were strongly related to annual whitebark pine cone production, which had a positive linear association with live whitebark pine basal area, and negative linear association with whitebark pine tree mortality and rust infection. From our data, we estimated that a threshold level of similar to 1000 cones/ha is needed for a high likelihood of seed dispersal by nutcrackers ( probability \u3e= 0.7), and that this level of cone production can be met by forests with live whitebark pine basal area \u3e5.0 m(2)/ha. The risk of mutualism disruption is greatest in northernmost Montana ( USA), where three-year mean cone production and live basal area fell below predicted threshold levels. There, nutcracker occurrence, seed dispersal, and whitebark pine regeneration were the lowest of the three ecosystems. Managers can use these threshold values to differentiate between restoration sites requiring planting of rust-resistant seedlings and sites where nutcracker seed dispersal can be expected

    Modeling comminution processes in ball mills as a canonical ensemble

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    A new approach to describe comminution processes in general ball mills as a macroscopic canonical ensemble is proposed. Using hamiltonian method, the model is able to take simultaneously into account the internal dynamics from mechanical motions inside the vial and external effects like electromagnetic and gravitational forces. Relevant physical observables are extracted using statistical mechanics approach through partition function at finite temperature. The method enables numerical calculation using Monte Carlo technique to obtain, for instance particle number evolution in term of system temperature. It is argued that the method is experimentally more verifiable than the conventional approaches based on geometrical displacements. An example of simulation for typical spex mill is also given.Comment: 16 pages, 7 figure

    NLO vector boson production with light jets

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    In this contribution we present recent progress in the computation of next-to-leading order (NLO) QCD corrections for the production of an electroweak vector boson in association with jets at hadron colliders. We focus on results obtained using the virtual matrix element library BLACKHAT in conjunction with SHERPA, focusing on results relevant to understanding the background to top production.Comment: 4+2 epsilon pages, Submitted for the proceedings of TOP2011 - 4th International Workshop on Top Quark Physics, 25-30th September 2011, Sant Feliu de Guixols, Spai

    Dose-finding study of a 90-day contraceptive vaginal ring releasing estradiol and segesterone acetate.

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    ObjectiveTo evaluate serum estradiol (E2) concentrations during use of 90-day contraceptive vaginal rings releasing E2 75, 100, or 200 mcg/day and segesterone acetate (SA) 200 mcg/day to identify a dose that avoids hypoestrogenism.Study designWe conducted a multicenter dose-finding study in healthy, reproductive-aged women with regular cycles with sequential enrollment to increasing E2 dose groups. We evaluated serum E2 concentrations twice weekly for the primary outcome of median E2 concentrations throughout initial 30-day use (target ≥40 pg/mL). In an optional 2-cycle extension substudy, we randomized participants to 2- or 4-day ring-free intervals per 30-day cycle to evaluate bleeding and spotting based on daily diary information.ResultsSixty-five participants enrolled in E2 75 (n = 22), 100 (n = 21), and 200 (n = 22) mcg/day groups; 35 participated in the substudy. Median serum E2 concentrations in 75 and 100 mcg/day groups were <40 pg/mL. In the 200 mcg/day group, median E2 concentrations peaked on days 4-5 of CVR use at 194 pg/mL (range 114-312 pg/mL) and remained >40 pg/mL throughout 30 days; E2 concentrations were 37 pg/mL (range 28-62 pg/mL) on days 88-90 (n = 11). Among the E2 200 mcg/day substudy participants, all had withdrawal bleeding following ring removal. The 2-day ring-free interval group reported zero median unscheduled bleeding and two (range 0-16) and three (range 0-19) unscheduled spotting days in extension cycles 1 and 2, respectively. The 4-day ring-free interval group reported zero median unscheduled bleeding or spotting days.ConclusionsEstradiol concentrations with rings releasing E2 200 mcg/day and SA 200 mcg/day avoid hypoestrogenism over 30-day use.ImplicationsA 90-day contraceptive vaginal ring releasing estradiol 200 mcg/day and segesterone acetate 200 mcg/day achieves estradiol concentrations that should avoid hypoestrogenism and effectively suppresses ovulation

    Critical Thinking in Accounting Textbooks

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    A textbook is the main source of learning in many universities, yet there are only a few studies which specifically evaluate accounting textbook. This research aimed to evaluate the accounting textbooks used in some Indonesian universities and is expected to provide recommendations of accounting textbooks which are potential to develop students' critical thinking ability. This study was a content analysis. The analysis was based on the Bloom's taxonomy as well as the indicators of contextual representation intensity level. The results demonstrated that critical thinking receives little attention, either in the components of learning objectives, practice exercises or the materials/main content. Accounting textbook written by foreign authors seems to have higher quality than those written by local authors. It is suggested that the accounting academicians in Indonesia collaborate with accounting practitioners to develop a better quality textbook by adapting the superiorities of textbooks written by foreign authors and eliminating the weakness

    Valoración analítica de opciones asiáticas aritméticas continuas mediante transformadas de Fourier

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    The second-order partial differential equation associated with the problem of pricing continuous arithmetic Asian options is presented, together with the application of the Fourier transform on the terms of the resulting equation after a series of variable changes. An analytical solution is obtained for the value of this type of options.En este artículo se presenta la deducción de la ecuación diferencial parcial de segundo orden asociada al problema de valoración de opciones asiáticas aritméticas continuas, junto con la aplicación de la transformada de Fourier sobre los términos de la ecuación resultante después de una serie de cambios de variable. Se obtiene una solución analítica para el valor de este tipo de opciones

    Quantum effects after decoherence in a quenched phase transition

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    We study a quantum mechanical toy model that mimics some features of a quenched phase transition. Both by virtue of a time-dependent Hamiltonian or by changing the temperature of the bath we are able to show that even after classicalization has been reached, the system may display quantum behaviour again. We explain this behaviour in terms of simple non-linear analysis and estimate relevant time scales that match the results of numerical simulations of the master-equation. This opens new possibilities both in the study of quantum effects in non-equilibrium phase transitions and in general time-dependent problems where quantum effects may be relevant even after decoherence has been completed.Comment: 7 pages, 7 figures, revtex, important revisions made. To be published in Phys. Rev.
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