659 research outputs found
Keynote Address: Why Are There so Many Injuries to Our Young Athletes? Professionalization and Specialization in Youth Sport
Keynote address at the Amateur Sports Symposium: Death of Amateurism: Implications for Sport and Health, delivered at the University of Baltimore School of Law on Thursday, October 28, 201
Changing medicine and building community: Maine’s Adverse Childhood Experiences momentum
Physicians are instrumental in community education, prevention, and intervention for adverse childhood experiences. In Maine, a statewide effort is focusing on education about adverse childhood experiences and ways that communities and physicians can approach childhood adversity. This article describes how education about adversity and resilience can positively change the practice of medicine and related fields. The Maine Resilience Building Network brings together ongoing programs, supports new ventures, and builds on existing resources to increase its impact. It exemplifies the collective impact model by increasing community knowledge, affecting medical practice, and improving lives.https://digitalcommons.library.umaine.edu/extension_family/1000/thumbnail.jp
Interference of a Tonks-Girardeau Gas on a Ring
We study the quantum dynamics of a one-dimensional gas of impenetrable bosons
on a ring, and investigate the interference that results when an initially
trapped gas localized on one side of the ring is released, split via an
optical-dipole grating, and recombined on the other side of the ring. Large
visibility interference fringes arise when the wavevector of the optical dipole
grating is larger than the effective Fermi wavevector of the initial gas.Comment: 7 pages, 3 figure
q-Newton binomial: from Euler to Gauss
A counter-intuitive result of Gauss (formulae (1.6), (1.7) below) is made
less mysterious by virtue of being generalized through the introduction of an
additional parameter
Solar Flares and Coronal Mass Ejections: A Statistically Determined Flare Flux-CME Mass Correlation
In an effort to examine the relationship between flare flux and corresponding
CME mass, we temporally and spatially correlate all X-ray flares and CMEs in
the LASCO and GOES archives from 1996 to 2006. We cross-reference 6,733 CMEs
having well-measured masses against 12,050 X-ray flares having position
information as determined from their optical counterparts. For a given flare,
we search in time for CMEs which occur 10-80 minutes afterward, and we further
require the flare and CME to occur within +/-45 degrees in position angle on
the solar disk. There are 826 CME/flare pairs which fit these criteria.
Comparing the flare fluxes with CME masses of these paired events, we find CME
mass increases with flare flux, following an approximately log-linear, broken
relationship: in the limit of lower flare fluxes, log(CME mass)~0.68*log(flare
flux), and in the limit of higher flare fluxes, log(CME mass)~0.33*log(flare
flux). We show that this broken power-law, and in particular the flatter slope
at higher flare fluxes, may be due to an observational bias against CMEs
associated with the most energetic flares: halo CMEs. Correcting for this bias
yields a single power-law relationship of the form log(CME mass)~0.70*log(flare
flux). This function describes the relationship between CME mass and flare flux
over at least 3 dex in flare flux, from ~10^-7 to 10^-4 W m^-2.Comment: 28 pages, 16 figures, accepted to Solar Physic
The Bogoliubov Theory of a BEC in Particle Representation
In the number-conserving Bogoliubov theory of BEC the Bogoliubov
transformation between quasiparticles and particles is nonlinear. We invert
this nonlinear transformation and give general expression for eigenstates of
the Bogoliubov Hamiltonian in particle representation. The particle
representation unveils structure of a condensate multiparticle wavefunction. We
give several examples to illustrate the general formalism.Comment: 10 pages, 9 figures, version accepted for publication in Phys. Rev.
The Social Climbing Game
The structure of a society depends, to some extent, on the incentives of the
individuals they are composed of. We study a stylized model of this interplay,
that suggests that the more individuals aim at climbing the social hierarchy,
the more society's hierarchy gets strong. Such a dependence is sharp, in the
sense that a persistent hierarchical order emerges abruptly when the preference
for social status gets larger than a threshold. This phase transition has its
origin in the fact that the presence of a well defined hierarchy allows agents
to climb it, thus reinforcing it, whereas in a "disordered" society it is
harder for agents to find out whom they should connect to in order to become
more central. Interestingly, a social order emerges when agents strive harder
to climb society and it results in a state of reduced social mobility, as a
consequence of ergodicity breaking, where climbing is more difficult.Comment: 14 pages, 9 figure
Collective excitations of trapped Bose condensates in the energy and time domains
A time-dependent method for calculating the collective excitation frequencies
and densities of a trapped, inhomogeneous Bose-Einstein condensate with
circulation is presented. The results are compared with time-independent
solutions of the Bogoliubov-deGennes equations. The method is based on
time-dependent linear-response theory combined with spectral analysis of
moments of the excitation modes of interest. The technique is straightforward
to apply, is extremely efficient in our implementation with parallel FFT
methods, and produces highly accurate results. The method is suitable for
general trap geometries, condensate flows and condensates permeated with vortex
structures.Comment: 6 pages, 3 figures small typos fixe
Instant luminescence chronologies? High resolution luminescence profiles using a portable luminescence reader
Establishing a robust chronology is fundamental to most palaeoenvironmental studies. However, the number and positioning of dated points is critical. Using a portable luminescence reader, it is possible to rapidly generate high resolution down core relative age profiles. Profiles of portable luminescence data from two coastal dunes were evaluated and compared with the results of particle size analysis, stratigraphy, and an independent historical chronology. Results show that, even in young samples, portable luminescence data is dominated by an age related signal which in homogeneous sediment need not be corrected for moisture, feldspar content changes or grain size. Profiles therefore provide relative chronologies from which accumulation phases can be established, and from which better targeted sampling and comparison to other sites could be undertaken. Even though they do not provide instant absolute chronologies, field-based portable luminescence profiling of Late Quaternary sites hold much potential to improve the resultant chronologies
Adiabatic Output Coupling of a Bose Gas at Finite Temperatures
We develop a general theory of adiabatic output coupling from trapped atomic
Bose-Einstein Condensates at finite temperatures. For weak coupling, the output
rate from the condensate, and the excited levels in the trap, settles in a time
proportional to the inverse of the spectral width of the coupling to the output
modes. We discuss the properties of the output atoms in the quasi-steady-state
where the population in the trap is not appreciably depleted. We show how the
composition of the output beam, containing condensate and thermal component,
may be controlled by changing the frequency of the output coupler. This
composition determines the first and second order coherence of the output beam.
We discuss the changes in the composition of the bose gas left in the trap and
show how nonresonant output coupling can stimulate either the evaporation of
thermal excitations in the trap or the growth of non-thermal excitations, when
pairs of correlated atoms leave the condensate.Comment: 22 pages, 6 Figs. To appear in Physical Review A All the typos from
the previous submission have been fixe
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