37,598 research outputs found
Labor Rights in the Generalized System of Preferences: A 20-Year Review
[Excerpt]In the fall of 1982, a small group of labor, religious, and human rights activists began charting a new course for human rights and workers\u27 rights in American trade policy. The principles of these labor rights advocates were straightforward:
1. No country should attract investment or gain an edge in international trade by violating workers\u27 rights;
2. No company operating in global trade should gain a competitive edge by violating workers\u27 rights; and,
3. Workers have a right to demand protection for labor rights in the international trade system, and to have laws to accomplish it.
The coalition that took shape 20 years ago made a labor rights amendment to the Generalized System of Preferences (GSP), the chief policy vehicle in U.S. law to promote these principles. This article reviews 20 years\u27 experience with the GSP labor rights clause
Two-Locus Likelihoods under Variable Population Size and Fine-Scale Recombination Rate Estimation
Two-locus sampling probabilities have played a central role in devising an
efficient composite likelihood method for estimating fine-scale recombination
rates. Due to mathematical and computational challenges, these sampling
probabilities are typically computed under the unrealistic assumption of a
constant population size, and simulation studies have shown that resulting
recombination rate estimates can be severely biased in certain cases of
historical population size changes. To alleviate this problem, we develop here
new methods to compute the sampling probability for variable population size
functions that are piecewise constant. Our main theoretical result, implemented
in a new software package called LDpop, is a novel formula for the sampling
probability that can be evaluated by numerically exponentiating a large but
sparse matrix. This formula can handle moderate sample sizes () and
demographic size histories with a large number of epochs (). In addition, LDpop implements an approximate formula for the sampling
probability that is reasonably accurate and scales to hundreds in sample size
(). Finally, LDpop includes an importance sampler for the posterior
distribution of two-locus genealogies, based on a new result for the optimal
proposal distribution in the variable-size setting. Using our methods, we study
how a sharp population bottleneck followed by rapid growth affects the
correlation between partially linked sites. Then, through an extensive
simulation study, we show that accounting for population size changes under
such a demographic model leads to substantial improvements in fine-scale
recombination rate estimation. LDpop is freely available for download at
https://github.com/popgenmethods/ldpopComment: 32 pages, 13 figure
Proceedings for the ICASE Workshop on Heterogeneous Boundary Conditions
Domain Decomposition is a complex problem with many interesting aspects. The choice of decomposition can be made based on many different criteria, and the choice of interface of internal boundary conditions are numerous. The various regions under study may have different dynamical balances, indicating that different physical processes are dominating the flow in these regions. This conference was called in recognition of the need to more clearly define the nature of these complex problems. This proceedings is a collection of the presentations and the discussion groups
Cosmological baryon and lepton number in the presence of electroweak fermion-number violation
In the presence of rapid fermion-number violation due to nonperturbative electroweak effects certain relations between the baryon number of the Universe and the lepton numbers of the Universe are predicted. In some cases the electron-neutrino asymmetry is exactly specified in terms of the baryon asymmetry. Without introducing new particles, beyond the usual quarks and leptons, it is necessary that the Universe possess a nonzero value of B - L prior to the epoch of fermion-number violation if baryon and lepton asymmetries are to survive. Contrary to intuition, even though electroweak processes violate B + L, a nonzero value of B + L persists after the epoch of rapid fermion-number violation. If the standard model is extended to include lepton-number violation, for example through Majorana neutrino masses, then electroweak processes will reduce the baryon number to zero even in the presence of an initial B - L unless 20 M(sub L) approximately greater than the square root of (T(sub B - L) m(sub P1)) where M(sub L) sets the scale of lepton number violation and T(sub B - L) is the temperature at which a B - L asymmetry is produced. In many models this implies that neutrinos must be so light that they cannot contribute appreciably to the mass density of the Universe
A Likelihood-Free Inference Framework for Population Genetic Data using Exchangeable Neural Networks
An explosion of high-throughput DNA sequencing in the past decade has led to
a surge of interest in population-scale inference with whole-genome data.
Recent work in population genetics has centered on designing inference methods
for relatively simple model classes, and few scalable general-purpose inference
techniques exist for more realistic, complex models. To achieve this, two
inferential challenges need to be addressed: (1) population data are
exchangeable, calling for methods that efficiently exploit the symmetries of
the data, and (2) computing likelihoods is intractable as it requires
integrating over a set of correlated, extremely high-dimensional latent
variables. These challenges are traditionally tackled by likelihood-free
methods that use scientific simulators to generate datasets and reduce them to
hand-designed, permutation-invariant summary statistics, often leading to
inaccurate inference. In this work, we develop an exchangeable neural network
that performs summary statistic-free, likelihood-free inference. Our framework
can be applied in a black-box fashion across a variety of simulation-based
tasks, both within and outside biology. We demonstrate the power of our
approach on the recombination hotspot testing problem, outperforming the
state-of-the-art.Comment: 9 pages, 8 figure
Effect of inelasticity on the phase transitions of a thin vibrated granular layer
We describe an experimental and computational investigation of the ordered
and disordered phases of a vibrating thin, dense granular layer composed of
identical metal spheres. We compare the results from spheres with different
amounts of inelasticity and show that inelasticity has a strong effect on the
phase diagram. We also report the melting of an ordered phase to a homogeneous
disordered liquid phase at high vibration amplitude or at large inelasticities.
Our results show that dissipation has a strong effect on ordering and that in
this system ordered phases are absent entirely in highly inelastic materials.Comment: 5 pages, 5 figures, published in Physical Review E. Title of first
version slightly change
Using Wave-Packet Interferometry to Monitor the External Vibrational Control of Electronic Excitation Transfer
We investigate the control of electronic energy transfer in molecular dimers
through the preparation of specific vibrational coherences prior to electronic
excitation, and its observation by nonlinear wave-packet interferometry.
Laser-driven coherent nuclear motion can affect the instantaneous resonance
between site-excited electronic states and thereby influence short-time
electronic excitation transfer (EET). We first illustrate this control
mechanism with calculations on a dimer whose constituent monomers undergo
harmonic vibrations. We then consider the use of nonlinear wave-packet
interferometry (nl-WPI) experiments to monitor the nuclear dynamics
accompanying EET in general dimer complexes following impulsive vibrational
excitation by a sub-resonant control pulse (or control pulse sequence). In
measurements of this kind, two pairs of polarized phase-related femtosecond
pulses following the control pulse generate superpositions of coherent nuclear
wave packets in optically accessible electronic states. Interference
contributions to the time- and frequency-integrated fluorescence signal due to
overlaps among the superposed wave packets provide amplitude-level information
on the nuclear and electronic dynamics. We derive the basic expression for a
control-pulse-dependent nl-WPI signal. The electronic transition moments of the
constituent monomers are assumed to have a fixed relative orientation, while
the overall orientation of the complex is distributed isotropically. We include
the limiting case of coincident arrival by pulses within each phase-related
pair in which control-influenced nl-WPI reduces to a fluorescence-detected
pump-probe difference experiment. Numerical calculations of pump-probe signals
based on these theoretical expressions are presented in the following paper
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