3,561 research outputs found

    {BOAO Photometric Survey of Galactic Open Clusters. II. Physical Parameters of 12 Open Clusters

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    We have initiated a long-term project, the BOAO photometric survey of open clusters, to enlarge our understanding of galactic structure using UBVI CCD photometry of open clusters which have been little studied before. This is the second paper of the project in which we present the photometry of 12 open clusters. We have determined the cluster parameters by fitting the Padova isochrones to the color-magnitude diagrams of the clusters. All the clusters except for Be 0 and NGC 1348 are found to be intermediate-age to old (0.2 - 4.0 Gyrs) open clusters with a mean metallicity of [Fe/H] = 0.0.Comment: 11 page

    Geometry, thermodynamics, and finite-size corrections in the critical Potts model

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    We establish an intriguing connection between geometry and thermodynamics in the critical q-state Potts model on two-dimensional lattices, using the q-state bond-correlated percolation model (QBCPM) representation. We find that the number of clusters of the QBCPM has an energy-like singularity for q different from 1, which is reached and supported by exact results, numerical simulation, and scaling arguments. We also establish that the finite-size correction to the number of bonds, has no constant term and explains the divergence of related quantities as q --> 4, the multicritical point. Similar analyses are applicable to a variety of other systems.Comment: 12 pages, 6 figure

    Patient-reported reasons for declining or discontinuing statin therapy: Insights from the PALM registry

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    Background: Many adults eligible for statin therapy for cardiovascular disease prevention are untreated. Our objective was to investigate patient‐reported reasons for statin underutilization, including noninitiation, refusal, and discontinuation.Methods and Results: This study included the 5693 adults recommended for statin therapy in the PALM (Patient and Provider Assessment of Lipid Management) registry. Patient surveys evaluated statin experience, reasons for declining or discontinuing statins, and beliefs about statins and cardiovascular disease risk. Overall, 1511 of 5693 adults (26.5%) were not on treatment. Of those not on a statin, 894 (59.2%) reported never being offered a statin, 153 (10.1%) declined a statin, and 464 (30.7%) had discontinued therapy. Women (relative risk: 1.22), black adults (relative risk: 1.48), and those without insurance (relative risk: 1.38) were most likely to report never being offered a statin. Fear of side effects and perceived side effects were the most common reasons cited for declining or discontinuing a statin. Compared with statin users, those who declined or discontinued statins were less likely to believe statins are safe (70.4% of current users vs. 36.9% of those who declined and 37.4% of those who discontinued) or effective (86.3%, 67.4%, and 69.1%, respectively). Willingness to take a statin was high; 67.7% of those never offered and 59.7% of patients who discontinued a statin would consider initiating or retrying a statin.Conclusions: More than half of patients eligible for statin therapy but not on treatment reported never being offered one by their doctor. Concern about side effects was the leading reason for statin refusal or discontinuation. Many patients were willing to reconsider statin therapy if offered

    Black Hole and Neutron Star Transients in Quiescence

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    We consider the X-ray luminosity difference between neutron star and black hole soft X-ray transients (NS and BH SXTs) in quiescence. The current observational data suggest that BH SXTs are significantly fainter than NS SXTs. The luminosities of quiescent BH SXTs are consistent with the predictions of binary evolution models for the mass transfer rate if (1) accretion occurs via an ADAF in these systems and (2) the accreting compact objects have event horizons. The luminosities of quiescent NS SXTs are not consistent with the predictions of ADAF models when combined with binary evolution models, unless most of the mass accreted in the ADAF is prevented from reaching the neutron star surface. We consider the possibility that mass accretion is reduced in quiescent NS SXTs because of an efficient propeller and develop a model of the propeller effect that accounts for the observed luminosities. We argue that modest winds from ADAFs are consistent with the observations while strong winds are probably not.Comment: LateX, 37 pages, 7 figures; Accepted for publication in The Astrophysical Journa

    Sum rules for e+eW+We^+e^- \to W^+W^- helicity amplitudes from BRS invariance

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    The BRS invariance of the electroweak gauge theory leads to relationships between amplitudes with external massive gauge bosons and amplitudes where some of these gauge bosons are replaced with their corresponding Nambu-Goldstone bosons. Unlike the equivalence theorem, these identities are exact at all energies. In this paper we discuss such identities which relate the process e+eW+We^+e^- \to W^+W^- to W±χW^\pm\chi^\mp and χ+χ\chi^+\chi^- production. By using a general form-factor decomposition for e+eW+We^+e^- \to W^+W^-, e+eW±χe^+e^- \to W^\pm \chi^\mp and e+eχ+χe^+e^- \to \chi^+\chi^- amplitudes, these identities are expressed as sum rules among scalar form factors. Because these sum rules may be applied order by order in perturbation theory, they provide a powerful test of higher order calculations. By using additional Ward-Takahashi identities we find that the various contributions are divided into separately gauge-invariant subsets, the sum rules applying independently to each subset. After a general discussion of the application of the sum rules we consider the one-loop contributions of scalar-fermions in the Minimal Supersymmetric Standard Model as an illustration.Comment: 37 pages, including 16 figure

    Impacts of programmable manufacturing technology: A review of recent studies and contingency formulation

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    This paper reviews the literature on the social impacts of programmable manufacturing technology (PMT). Several perspectives on the social impact of technology are identified ranging from simple additive models that view technology as having a set of individual and independent causal impacts to a contingency perspective which views the impact of technology as dependent on technical and organizational characteristics. The paper statistically summarizes 30 empirical studies within the 1986-1990 period and finds common trends in findings as well as contradictory evidence. The common trends are that PMT tends to lead to more organic organizations, but also meets with negative employee attitudes, stress, and perceptions of reduced job security and mobility. The contradictory evidence is that most studies report simple, additive effects, while a substantial portion find that the impacts depend on a wide range of contingency variables. The authors argue that simplistic views of PMT as being a homogeneous set of technologies with uni-directional non-contingent social impacts is neither realistic nor useful. A number of future research directions in this area are suggested.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30599/1/0000236.pd

    Boundary Effects on Spectral Properties of Interacting Electrons in One Dimension

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    The single electron Green's function of the one-dimensional Tomonaga-Luttinger model in the presence of open boundaries is calculated with bosonization methods. We show that the critical exponents of the local spectral density and of the momentum distribution change in the presence of a boundary. The well understood universal bulk behavior always crosses over to a boundary dominated regime for small energies or small momenta. We show this crossover explicitly for the large-U Hubbard model in the low-temperature limit. Consequences for photoemission experiments are discussed.Comment: revised and reformatted paper to appear in Phys. Rev. Lett. (Feb. 1996). 5 pages (revtex) and 3 embedded figures (macro included). A complete postscript file is available from http://FY.CHALMERS.SE/~eggert/luttinger.ps or by request from [email protected]

    Environmental Justice and Community-Based Participatory Research in Texas Borderland Colonias

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    Objective An innovative academic-community partnership studied daily decisions in communities of mostly Spanish-speaking, low-income residents of colonias in Hidalgo County, TX, about risk of exposure to fish contaminated by PCBs at an Environment Protection Agency (EPA) Superfund site. Design and Sample The team used focus group interviews with colonia residents and content analysis to assess knowledge of risk related to the Superfund site, the Donna Reservoir and Canal System. Results (1) many lacked knowledge of the Superfund site contamination; (2) a few participants fished at the lake, knew people who did so, and consumed the catch, but most participants feared going there; (3) some participants remember receiving messages saying not to fish at the site, although they recalled nothing about contamination, but most participants knew of no such messages; (4) many use cell phones to get local information through personal networks and several Spanish-language news sources, but they have no consistent, culturally tailored local information source. Conclusions The findings indicate the need for further efforts to design culturally tailored means of communication and messages to inform local communities widely about the dangers related to the Superfund site and thus decrease health disparities resulting from consuming fish from the site
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