53,742 research outputs found
What's new in the diagnosis and management of food allergy in children?
This article reviews the recent advances in the diagnosis and management of IgE mediated food allergy in children. It will encompass the emerging technology of component testing; moves to standardization of the allergy food challenge; permissive diets which allow for inclusion of extensively heated food allergens with allergen avoidance; and strategies for accelerating tolerance and food desensitization including the use of adjuvants for specific tolerance induction
Teaching Peirce to Undergraduates
Fourteen philosophers share their experience teaching Peirce to undergraduates in a
variety of settings and a variety of courses. The latter include introductory philosophy
courses as well as upper-level courses in American philosophy, philosophy of religion,
logic, philosophy of science, medieval philosophy, semiotics, metaphysics, etc., and even an upper-level course devoted entirely to Peirce. The project originates in a session devoted to teaching Peirce held at the 2007 annual meeting of the Society for the Advancement of American Philosophy. The session, organized by James Campbell and Richard Hart, was co-sponsored by the American Association of Philosophy Teachers
Equilibration and nonclassicality of a double-well potential
A double well loaded with bosonic atoms represents an ideal candidate to
simulate some of the most interesting aspects in the phenomenology of
thermalisation and equilibration. Here we report an exhaustive analysis of the
dynamics and steady state properties of such a system locally in contact with
different temperature reservoirs. We show that thermalisation only occurs
'accidentally'. We further examine the nonclassical features and energy fluxes
implied by the dynamics of the double-well system, thus exploring its
finite-time thermodynamics in relation to the settlement of nonclassical
correlations between the wells.Comment: 10 pages, 7 figures, Close to published versio
Global and local thermometry schemes in coupled quantum systems
We study the ultimate bounds on the estimation of temperature for an
interacting quantum system. We consider two coupled bosonic modes that are
assumed to be thermal and using quantum estimation theory establish the role
the Hamiltonian parameters play in thermometry. We show that in the case of a
conserved particle number the interaction between the modes leads to a decrease
in the overall sensitivity to temperature, while interestingly, if particle
exchange is allowed with the thermal bath the converse is true. We explain this
dichotomy by examining the energy spectra. Finally, we devise experimentally
implementable thermometry schemes that rely only on locally accessible
information from the total system, showing that almost Heisenberg limited
precision can still be achieved, and we address the (im)possibility for
multiparameter estimation in the system.Comment: 16 pages, 5 figures. Close to published versio
A conversation with 590 nascent entrepreneurs
This paper summarizes interviews from 1998 with 590 individuals trying to create a business centered around five questions: “Who are you?”, “What are you trying to accomplish?”, “What have you and others put into the business?”, “What have you accomplished?”, “What remains to be done?” There is a great deal of heterogeneity across these Nascent entrepreneurs, but they tend to have more education than the general population. Growing up in a family in which one or both parents had a business does not seem to be an important determinant of entry into entrepreneurship for males, while it seems to be of some importance for females. Most of the nascent businesses are in retail and consumer services, and about 50 percent of nascent entrepreneurs expect to become employers within five years of the business’s birth. Most nascent entrepreneurs have already made personally-significant investments of time and money in their firms; and nearly all of them are saving for their firms out of non-business income. For about half of the sample, these investments have yielded a fully-specified product; and the remainder are still in the product development stage. Family and friends are an importance source of seed money for many Nascent Entrepreneurs. Formal credit markets have been requested for funds only by a minority of Nascent Entrepreneurs, and almost half of these applicants have been denied loans. About 40% of the Nascent Entrepreneurs believe that their businesses require significantly greater equity before they can attract external funds.Business ; Business enterprises
Cost of counterdiabatic driving and work output
Unitary processes allow for the transfer of work to and from Hamiltonian
systems. However, to achieve nonzero power for the practical extraction of
work, these processes must be performed within a finite time, which inevitably
induces excitations in the system. We show that depending on the time scale of
the process and the physical realization of the external driving employed, the
use of counterdiabatic quantum driving to extract more work is not always
effective. We also show that by virtue of the two-time energy measurement
definition of quantum work, the cost of counterdiabatic driving can be
significantly reduced by selecting a restricted form of the driving Hamiltonian
that depends on the outcome of the first energy measurement. Lastly, we
introduce a measure, the exigency, that quantifies the need for an external
driving to preserve quantum adiabaticity which does not require knowledge of
the explicit form of the counterdiabatic drivings, and can thus always be
computed. We apply our analysis to systems ranging from a two-level
Landau-Zener problem to many-body problems, namely, the quantum Ising and
Lipkin-Meshkov-Glick models.Comment: 9 pages, 4 figure
Dynamics and Asymptotics of Correlations in a Many-Body Localized System
We examine the dynamics of nearest-neighbor bipartite concurrence and total
correlations in the spin-1/2 model with random fields. We show, starting
from factorized random initial states, that the concurrence can suffer
entanglement sudden death in the long time limit and therefore may not be a
useful indicator of the properties of the system. In contrast, we show that the
total correlations capture the dynamics more succinctly, and further reveal a
fundamental difference in the dynamics governed by the ergodic versus many-body
localized phases, with the latter exhibiting dynamical oscillations. Finally,
we consider an initial state composed of several singlet pairs and show that by
fixing the correlation properties, while the dynamics do not reveal noticeable
differences between the phases, the long-time values of the correlation
measures appear to indicate the critical region.Comment: 5 pages, 5 figures. Close to published versio
Dynamics in the Sherrington-Kirkpatrick Ising spin glass at and above Tg
A detailed numerical study is made of relaxation at equilibrium in the
Sherrington-Kirkpatrick Ising spin glass model, at and above the critical
temperature Tg. The data show a long time stretched exponential relaxation q(t)
~ exp[-(t/tau(T))^beta(T)] with an exponent beta(T) tending to ~ 1/3 at Tg. The
results are compared to those which were observed by Ogielski in the 3d ISG
model, and are discussed in terms of a phase space percolation transition
scenario.Comment: 6 pages, 7 figure
W, Z and photon production in CMS
The production of electroweak bosons (photons, W and Z particles) in PbPb and
pp collisions at sqrt(s) = 2.76 TeV per interacting nucleon pair has been
measured with the CMS detector at the LHC. Direct photon production is studied
using samples of isolated photons. W and Z bosons are reconstructed through
their leptonic decay into muons. Their production rate in PbPb data is studied
as a function of the centrality of the collision and compared to that in pp
interactions, once normalized by the number of binary nucleon-nucleon
interactions. The results are also compared to next-to-leading-order
perturbative QCD calculations.Comment: Proceedings from Plenary Talk at 5th International Conference on Hard
and Electromagnetic Probes of High-Energy Nuclear Collisions (Hard Probes
2012) at Cagliari (Italia
Nonclassicality and criticality in symmetry-protected magnetic phases
Quantum and global discord in a spin-1 Heisenberg chain subject to single-ion
anisotropy (uniaxial field) are studied using exact diagonalisation and the
density matrix renormalisation group (DMRG). We find that these measures of
quantum nonclassicality are able to detect the quantum phase transitions
confining the symmetry protected Haldane phase and show critical scaling with
universal exponents. Moreover, in the case of thermal states, we find that
quantum discord can increase with increasing temperature.Comment: 7 pages, 6 figures, Close to published version. Includes a link to
data used for the figure
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