6,997 research outputs found

    Social Memory as Festive Therapy and Village Politics

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    The capacity of memory to heal has recently been of particular interest in both anthropology and psychology. Creating a narrative from fragmentary memories makes sense of past pain by giving it shape and meaning. The villagers of Rocca Sinibalda in central Italy had such an opportunity in 1556, after suffering sack and destruction, harsh forced labour, oppressive fines and taxes, and severe punishments. During the festive atmosphere of Carnival villagers both told their stories to a commissario sent from Rome to investigate and listened to those of others. Like a modern patient, a sixteenth-century village could perhaps rebuild its past in a festival of memory that was both curative and political.Le pouvoir de guĂ©rison de la mĂ©moire a rĂ©cemment suscitĂ© un intĂ©rĂȘt particulier dans les champs de l’anthropologie et de la psychologie. Faire le rĂ©cit des Ă©vĂ©nements Ă  partir de souvenirs fragmentaires permet de comprendre la douleur passĂ©e en lui confĂ©rant sens et forme. Les villageois de Rocca Sinibalda, au centre de l’Italie, ont eu une telle occasion en 1556, aprĂšs avoir vu leur village pillĂ© et dĂ©truit, Ă©tĂ© contraints Ă  de durs travaux forcĂ©s et s’ĂȘtre vu infliger des amendes et des taxes oppressives ainsi que de lourdes punitions. Durant l’atmosphĂšre de fĂȘte du carnaval, les villageois racontaient leur histoire Ă  un commissario dĂ©pĂȘchĂ© de Rome pour faire enquĂȘte et ils Ă©coutaient celle des autres. Tel un patient moderne, un village du seiziĂšme siĂšcle pouvait peut-ĂȘtre rebĂątir son passĂ© Ă  l’occasion d’un festival de la mĂ©moire Ă  la fois curatif et politique

    Doubly heavy hadrons and the domain of validity of doubly heavy diquark--anti-quark symmetry

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    In the limit of heavy quark masses going to infinity, a symmetry is known to emerge in QCD relating properties of hadrons with two heavy quarks to analogous states with one heavy anti-quark. A key question is whether the charm mass is heavy enough so that this symmetry is manifest in at least an approximate manner. The issue is crucial in attempting to understand the recent reports by the SELEX Collaboration of doubly charmed baryons. We argue on very general grounds that the charm quark mass is substantially too light for the symmetry to emerge automatically via colour coulombic interactions. However, the symmetry could emerge approximately depending on the dynamical details.Comment: 9 page

    On the Existence of Heavy Pentaquarks: The large Nc and Heavy Quark Limits and Beyond

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    We present a very general argument that the analogue of a heavy pentaquark (a state with the quantum numbers of a baryon combined with an additional light quark and a heavy antiquark) must exist as a particle stable under strong interactions in the combined heavy quark and large Nc limits of QCD. Moreover, in the combined limit these heavy pentaquark states fill multiplets of SU(4)xO(8)xSU(2). We explore the question of whether corrections in the combined 1/Nc and 1/mQ expansions are sufficiently small to maintain this qualitative result. Since no model-independent way is known to answer this question, we use a class of ``realistic'' hadronic models in which a pentaquark can be formed via nucleon-heavy meson binding through a pion-exchange potential. These models have the virtue that they necessarily yield the correct behavior in the combined limit, and the long-distance parts of the interactions are model independent. If the long-distance attraction in these models were to predict bound states in a robust way (i.e., largely insensitive to the details of the short-range interaction), then one could safely conclude that heavy pentaquarks do exist. However, in practice the binding does depend very strongly on the details of the short-distance physics, suggesting that the real world is not sufficiently near the combined large Nc, mQ limit to use it as a reliable guide. Whether stable heavy pentaquarks exist remains an open question.Comment: 11 pages; references adde

    Oral Appliance Therapy for the Management of Obstructive Sleep Apnea

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    In recent years, the medical profession has begun to recognize the role of sleep hygiene as it pertains to patient health. Types of sleep disordered breathing (SDB) include snoring, obstructive sleep apnea (OSA), central sleep apnea and a mix of obstructive and central apnea. OSA is the most common category of SDB. The apneas are now known affect cardiovascular health and neuro-behavioral issues. In recent years, the dental profession has become involved in managing snoring and certain OSA problems using oral appliance therapy (OAT). This treatment by dentists is now well accepted by the medical profession. This paper will review the basics of OSA, and how the dentist may be involved in providing OAT for these patients

    Pion Photoproduction Amplitude Relations in the 1/N_c Expansion

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    We derive expressions for pion photoproduction amplitudes in the 1/N_c expansion of QCD, and obtain linear relations directly from this expansion that relate electromagnetic multipole amplitudes at all energies. The leading-order relations in 1/N_c compare favorably with available data, while the next-to-leading order relations seem to provide only a small improvement. However, when resonance parameters are compared directly, the agreement at O(1/N_c) or O(1/N_c^2) is impressive.Comment: 19 pages, ReVTeX, 50 eps files combine into 5 compound figure

    Resolving the Large-N Nuclear Potential Puzzle

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    The large NcN_c nuclear potential puzzle arose because three- and higher-meson exchange contributions to the nucleon-nucleon potential did not automatically yield cancellations that make these contributions consistent with the general large NcN_c scaling rules for the potential. Here it is proposed that the resolution to this puzzle is that the scaling rules only apply for energy-independent potentials while all of the cases with apparent inconsistencies were for energy-dependent potentials. It is shown explicitly how energy-dependent potentials can have radically different large N behavior than an equivalent energy-independent one. One class of three-meson graphs is computed in which the contribution to the energy-independent potential is consistent with the general large N rules even though the energy-dependent potential is not.Comment: Corrections to the toy mode

    The collective quantization of three-flavored Skyrmions revisited

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    A self-consistent large NcN_c approach is developed for the collective quantization of SU(3) flavor hedgehog solitons, such as the Skyrmion. The key to this analysis is the determination of all of the zero modes associated with small fluctuations around the hedgehog. These are used in the conventional way to construct collective coordinates. This approach differs from previous work in that it does not implicitly assume that each static zero mode is associated with a dynamical zero mode. It is demonstrated explicitly in the context of the Skyrmion that there are fewer dynamical zero modes than static ones due to the Witten-Wess-Zumino term in the action. Group-theoretic methods are employed to identify the physical states resulting from canonical quantization of the collectively rotating soliton. The collective states fall into representations of SU(3) flavor labeled by (p,q)(p,q) and are given by (2J,Nc2−J)(2J, \frac{Nc}{2} -J) where J=1/2,3/2,...J={1/2},{3/2},... is the spin of the collective state. States with strangeness S>0S > 0 do not arise as collective states from this procedure; thus the ξ+\theta^{+} (pentaquark) resonance does not arise as a collective excitation in models of this type.Comment: 12 pages; uses package "youngtab

    Lasing and cooling in a hot cavity

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    We present a microscopic laser model for many atoms coupled to a single cavity mode, including the light forces resulting from atom-field momentum exchange. Within a semiclassical description, we solve the equations for atomic motion and internal dynamics to obtain analytic expressions for the optical potential and friction force seen by each atom. When optical gain is maximum at frequencies where the light field extracts kinetic energy from the atomic motion, the dynamics combines optical lasing and motional cooling. From the corresponding momentum diffusion coefficient we predict sub-Doppler temperatures in the stationary state. This generalizes the theory of cavity enhanced laser cooling to active cavity systems. We identify the gain induced reduction of the effective resonator linewidth as key origin for the faster cooling and lower temperatures, which implys that a bad cavity with a gain medium can replace a high-Q cavity. In addition, this shows the importance of light forces for gas lasers in the low-temperature limit, where atoms can arrange in a periodic pattern maximizing gain and counteracting spatial hole burning. Ultimately, in the low temperature limit, such a setup should allow to combine optical lasing and atom lasing in single device.Comment: 11 pages, 6 figure
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