116 research outputs found

    Academic freedom: in justification of a universal ideal

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    This paper examines the justification for, and benefits of, academic freedom to academics, students, universities and the world at large. The paper surveys the development of the concept of academic freedom within Europe, more especially the impact of the reforms at the University of Berlin instigated by Wilhelm von Humboldt. Following from this, the paper examines the reasons why the various facets of academic freedom are important and why the principle should continue to be supported

    Production and Decay of D_1(2420)^0 and D_2^*(2460)^0

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    We have investigated D+π−D^{+}\pi^{-} and D∗+π−D^{*+}\pi^{-} final states and observed the two established L=1L=1 charmed mesons, the D1(2420)0D_1(2420)^0 with mass 2421−2−2+1+22421^{+1+2}_{-2-2} MeV/c2^{2} and width 20−5−3+6+320^{+6+3}_{-5-3} MeV/c2^{2} and the D2∗(2460)0D_2^*(2460)^0 with mass 2465±3±32465 \pm 3 \pm 3 MeV/c2^{2} and width 28−7−6+8+628^{+8+6}_{-7-6} MeV/c2^{2}. Properties of these final states, including their decay angular distributions and spin-parity assignments, have been studied. We identify these two mesons as the jlight=3/2j_{light}=3/2 doublet predicted by HQET. We also obtain constraints on {\footnotesize ΓS/(ΓS+ΓD)\Gamma_S/(\Gamma_S + \Gamma_D)} as a function of the cosine of the relative phase of the two amplitudes in the D1(2420)0D_1(2420)^0 decay.Comment: 15 pages in REVTEX format. hardcopies with figures can be obtained by sending mail to: [email protected]

    Measurement of the branching fraction for ΄(1S)→τ+τ−\Upsilon (1S) \to \tau^+ \tau^-

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    We have studied the leptonic decay of the ΄(1S)\Upsilon (1S) resonance into tau pairs using the CLEO II detector. A clean sample of tau pair events is identified via events containing two charged particles where exactly one of the particles is an identified electron. We find B(΄(1S)→τ+τ−)=(2.61 ± 0.12 +0.09−0.13)B(\Upsilon(1S) \to \tau^+ \tau^-) = (2.61~\pm~0.12~{+0.09\atop{-0.13}})%. The result is consistent with expectations from lepton universality.Comment: 9 pages, RevTeX, two Postscript figures available upon request, CLNS 94/1297, CLEO 94-20 (submitted to Physics Letters B

    Measurement of the Decay Asymmetry Parameters in Λc+→Λπ+\Lambda_c^+ \to \Lambda\pi^+ and Λc+→Σ+π0\Lambda_c^+ \to \Sigma^+\pi^0

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    We have measured the weak decay asymmetry parameters (\aLC ) for two \LC\ decay modes. Our measurements are \aLC = -0.94^{+0.21+0.12}_{-0.06-0.06} for the decay mode Λc+→Λπ+\Lambda_c^+ \to \Lambda\pi^+ and \aLC = -0.45\pm 0.31 \pm 0.06 for the decay mode Λc→Σ+π0\Lambda_c \to \Sigma^+\pi^0 . By combining these measurements with the previously measured decay rates, we have extracted the parity-violating and parity-conserving amplitudes. These amplitudes are used to test models of nonleptonic charmed baryon decay.Comment: 11 pages including the figures. Uses REVTEX and psfig macros. Figures as uuencoded postscript. Also available as http://w4.lns.cornell.edu/public/CLNS/1995/CLNS95-1319.p

    Observation of the Ξc+\Xi_c^+ Charmed Baryon Decays to ÎŁ+K−π+\Sigma^+ K^-\pi^+, ÎŁ+Kˉ∗0\Sigma^+ \bar{K}^{*0}, and ΛK−π+π+\Lambda K^-\pi^+\pi^+

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    We have observed two new decay modes of the charmed baryon Ξc+\Xi_c^+ into ÎŁ+K−π+\Sigma^+ K^-\pi^+ and ÎŁ+Kˉ∗0\Sigma^+ \bar{K}^{*0} using data collected with the CLEO II detector. We also present the first measurement of the branching fraction for the previously observed decay mode Ξc+→ΛK−π+π+\Xi_c^+\to\Lambda K^-\pi^+\pi^+. The branching fractions for these three modes relative to Ξc+→Ξ−π+π+\Xi_c^+\to\Xi^-\pi^+\pi^+ are measured to be 1.18±0.26±0.171.18 \pm 0.26 \pm 0.17, 0.92±0.27±0.140.92 \pm 0.27 \pm 0.14, and 0.58±0.16±0.070.58 \pm 0.16 \pm 0.07, respectively.Comment: 12 page uuencoded postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

    Search for CP Violation in D^0--> K_S^0 pi^+pi^-

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    We report on a search for CP violation in the decay of D0 and D0B to Kshort pi+pi-. The data come from an integrated luminosity of 9.0 1/fb of e+e- collisions at sqrt(s) ~ 10 GeV recorded with the CLEO II.V detector. The resonance substructure of this decay is well described by ten quasi-two-body decay channels (K*-pi+, K*0(1430)-pi+, K*2(1430)-pi+, K*(1680)-pi+, Kshort rho, Kshort omega, Kshort f0(980), Kshort f2(1270), Kshort f0(1370), and the ``wrong sign'' K*+ pi-) plus a small non-resonant component. We observe no evidence for CP violation in the amplitudes and phases that describe the decay D0 to K_S^0 pi+pi-.Comment: 10 pages, 3 figures, also available at http://w4.lns.cornell.edu/public/CLNS/, submitted to PR

    Multiple drivers of decline in the global status of freshwater crayfish (Decapoda: Astacidea)

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    International audienceRates of biodiversity loss are higher in freshwater ecosystems than in most terrestrial or marine ecosystems, making freshwater conservation a priority. However, prioritization methods are impeded by insufficient knowledge on the distribution and conservation status of freshwater taxa, particularly invertebrates. We evaluated the extinction risk of the world's 590 freshwater crayfish species using the IUCN Categories and Criteria and found 32% of all species are threatened with extinction. The level of extinction risk differed between families, with proportionally more threatened species in the Parastacidae and Astacidae than in the Cambaridae. Four described species were Extinct and 21% were assessed as Data Deficient. There was geographical variation in the dominant threats affecting the main centres of crayfish diversity. The majority of threatened US and Mexican species face threats associated with urban development, pollution, damming and water management. Conversely, the majority of Australian threatened species are affected by climate change, harvesting, agriculture and invasive species. Only a small proportion of crayfish are found within the boundaries of protected areas, suggesting that alternative means of long-term protection will be required. Our study highlights many of the significant challenges yet to come for freshwater biodiversity unless conservation planning shifts from a reactive to proactive approach

    Toward a 21st-century health care system: Recommendations for health care reform

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    The coverage, cost, and quality problems of the U.S. health care system are evident. Sustainable health care reform must go beyond financing expanded access to care to substantially changing the organization and delivery of care. The FRESH-Thinking Project (www.fresh-thinking.org) held a series of workshops during which physicians, health policy experts, health insurance executives, business leaders, hospital administrators, economists, and others who represent diverse perspectives came together. This group agreed that the following 8 recommendations are fundamental to successful reform: 1. Replace the current fee-for-service payment system with a payment system that encourages and rewards innovation in the efficient delivery of quality care. The new payment system should invest in the development of outcome measures to guide payment. 2. Establish a securely funded, independent agency to sponsor and evaluate research on the comparative effectiveness of drugs, devices, and other medical interventions. 3. Simplify and rationalize federal and state laws and regulations to facilitate organizational innovation, support care coordination, and streamline financial and administrative functions. 4. Develop a health information technology infrastructure with national standards of interoperability to promote data exchange. 5. Create a national health database with the participation of all payers, delivery systems, and others who own health care data. Agree on methods to make de-identified information from this database on clinical interventions, patient outcomes, and costs available to researchers. 6. Identify revenue sources, including a cap on the tax exclusion of employer-based health insurance, to subsidize health care coverage with the goal of insuring all Americans. 7. Create state or regional insurance exchanges to pool risk, so that Americans without access to employer-based or other group insurance could obtain a standard benefits package through these exchanges. Employers should also be allowed to participate in these exchanges for their employees' coverage. 8. Create a health coverage board with broad stakeholder representation to determine and periodically update the affordable standard benefit package available through state or regional insurance exchanges

    Statistical mechanics of two-dimensional vortices and stellar systems

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    The formation of large-scale vortices is an intriguing phenomenon in two-dimensional turbulence. Such organization is observed in large-scale oceanic or atmospheric flows, and can be reproduced in laboratory experiments and numerical simulations. A general explanation of this organization was first proposed by Onsager (1949) by considering the statistical mechanics for a set of point vortices in two-dimensional hydrodynamics. Similarly, the structure and the organization of stellar systems (globular clusters, elliptical galaxies,...) in astrophysics can be understood by developing a statistical mechanics for a system of particles in gravitational interaction as initiated by Chandrasekhar (1942). These statistical mechanics turn out to be relatively similar and present the same difficulties due to the unshielded long-range nature of the interaction. This analogy concerns not only the equilibrium states, i.e. the formation of large-scale structures, but also the relaxation towards equilibrium and the statistics of fluctuations. We will discuss these analogies in detail and also point out the specificities of each system.Comment: Chapter of the forthcoming "Lecture Notes in Physics" volume: ``Dynamics and Thermodynamics of Systems with Long Range Interactions'', T. Dauxois, S. Ruffo, E. Arimondo, M. Wilkens Eds., Lecture Notes in Physics Vol. 602, Springer (2002
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