6,997 research outputs found
Social Memory as Festive Therapy and Village Politics
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 lâanthropologie et de la psychologie. Faire le rĂ©cit des Ă©vĂ©nements
à partir de souvenirs fragmentaires permet de comprendre la douleur passée
en lui conférant sens et forme. Les villageois de Rocca Sinibalda, au centre de
lâItalie, 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 sâĂȘtre vu infliger des amendes et
des taxes oppressives ainsi que de lourdes punitions. Durant lâatmosphĂšre 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 lâoccasion dâun
festival de la mémoire à la fois curatif et politique
Pascal Brioist, HervĂ© DrĂ©villon et Pierre Serna â Croiser le fer : violence et culture de l'Ă©pĂ©e dans la France moderne (XVIe-XVIIIe siĂšcle)
Doubly heavy hadrons and the domain of validity of doubly heavy diquark--anti-quark symmetry
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
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
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
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
The large 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 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
A self-consistent large 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 and are given by
where is the spin of the collective state. States with
strangeness do not arise as collective states from this procedure; thus
the (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
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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