425 research outputs found
La incierta transición de Afganistán: del caos a la normalidad
Este documento de trabajo es una traducción, realizada por el Real Instituto Elcano, del publicado originalmente en inglés por el Council on Foreign Relations (CFR), organismo sin afiliación política, con sedes en Washington y Nueva York, dedicado a la publicación y difusión de ideas para facilitar la comprensión de la situación mundial y de las medidas de política exterior adoptadas en los Estados Unidos y otros Estados
Entanglement and visibility at the output of a Mach-Zehnder interferometer
We study the entanglement between the two beams exiting a Mach-Zehnder
interferometer fed by a couple of squeezed-coherent states with arbitrary
squeezing parameter. The quantum correlations at the output are function of the
internal phase-shift of the interferometer, with the output state ranging from
a totally disentangled state to a state whose degree of entanglement is an
increasing function of the input squeezing parameter. A couple of squeezed
vacuum at the input leads to maximum entangled state at the output. The fringes
visibilities resulting from measuring the coincidence counting rate or the
squared difference photocurrent are evaluated and compared each other.
Homodyne-like detection turns out to be preferable in almost all situations,
with the exception of the very low signals regime.Comment: 6 figs, accepted for publication on PRA, see also
http://enterprise.pv.infn.it/~pari
‘Teachers’ to ‘academics’: the implementation of a modernisation project at one UK post-92 university
Among the many external forces that have impacted upon institutions, league tables have been the dynamic to which universities across the world are now responding. Following the appointment of a new vice-chancellor at one post-92 UK university, a modernisation project was introduced aimed at maximising the institutions’ research standing. For the institutional actors, the university’s lecturers, this modernisation project demanded a change in their working practices from one which had focused on teaching related activities to a situation where an emphasis was to be placed upon research. This study examines how university teachers at this institution understood and responded to the modernisation project to acquire research skills and provides an insight into a path-breaking strategic plan that was enacted within an historically dependent setting. It muses on the dialectics of institutional path dependency and the path breaking effect of a modernisation project that was stimulated by new managerialism
The Paired Availability Design for Historical Controls
BACKGROUND: Although a randomized trial represents the most rigorous method of evaluating a medical intervention, some interventions would be extremely difficult to evaluate using this study design. One alternative, an observational cohort study, can give biased results if it is not possible to adjust for all relevant risk factors. METHODS: A recently developed and less well-known alternative is the paired availability design for historical controls. The paired availability design requires at least 10 hospitals or medical centers in which there is a change in the availability of the medical intervention. The statistical analysis involves a weighted average of a simple "before" versus "after" comparison from each hospital or medical center that adjusts for the change in availability. RESULTS: We expanded requirements for the paired availability design to yield valid inference. (1) The hospitals or medical centers serve a stable population. (2) Other aspects of patient management remain constant over time. (3) Criteria for outcome evaluation are constant over time. (4) Patient preferences for the medical intervention are constant over time. (5) For hospitals where the intervention was available in the "before" group, a change in availability in the "after group" does not change the effect of the intervention on outcome. CONCLUSION: The paired availability design has promise for evaluating medical versus surgical interventions, in which it is difficult to recruit patients to a randomized trial
Further Search for the Two-Photon Production of the Glueball Candidate
The CLEOII detector at the Cornell e+ e- storage ring CESR has been used to
search for the two-photon production of the decaying into pi+ pi-.
No evidence for a signal is found in data corresponding to an integrated
luminosity of 4.77/fb and a 95% CL upper limit on of 2.5 eV is set. If this result is combined with the BES Collaboration's
measurement of in radiative decay, a 95% CL
lower limit on the stickiness of the of 73 is obtained. If the
recent CLEO result for \Gamma_{two-photon} * BR{\K_S K_S} is combined with
the present result, the stickiness of the is found to be larger
than 102 at the 95% CL. These results for the stickiness (the ratio of the
probabilities for two-gluon coupling and two-photon coupling) provide further
support for a substantial neutral parton content in the .Comment: 8 pages, postscript file also available through
http://w4.lns.cornell.edu/public/CLN
Limit on the Two-Photon Production of the Glueball Candidate at CLEO
We use the CLEO detector at the Cornell electron-positron storage ring, CESR,
to search for the two-photon production of the glueball candidate f_J(2220) in
its decay to K_s K_s. We present a restrictive upper limit on the product of
the two-photon partial width and the K_s K_s branching fraction. We use this
limit to calculate a lower limit on the stickiness, which is a measure of the
two-gluon coupling relative to the two-photon coupling. This limit on
stickiness indicates that the f_J(2220) has substantial glueball content.Comment: 9 page postscript file, postscript file also available through
http://w4.lns.cornell.edu/public/CLN
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