1,274 research outputs found
The Stabilization and Structural Adjustment Procedures of the International Monetary Fund and the World Bank
The IMF and the World Bank began to attach structural adjustment restrictions to many of their loans to developing countries in the early 1980s. Some of these restrictions are not based on solid economic ground and are, in many cases not effective in improving the economic standing of the countries that receive loans. In addition, there was also a misdiagnosis of the problems that occurred in the underdeveloped countries of the world. Under the IMF/World Bank paradigm, the difficulties that most underdeveloped countries experienced were due to internal distortions and non-effective development strategies. Evidence to the contrary shows that many of the problems that these underdeveloped nations experienced in the 1970s and early 1980s were mainly exogenous and out of the control of the individual countries, such as: Two severe oil shocks, a world wide recession, and increased real interest rates
Lower bounds for polynomials using geometric programming
We make use of a result of Hurwitz and Reznick, and a consequence of this
result due to Fidalgo and Kovacec, to determine a new sufficient condition for
a polynomial of even degree to be a sum of
squares. This result generalizes a result of Lasserre and a result of Fidalgo
and Kovacec, and it also generalizes the improvements of these results given in
[6]. We apply this result to obtain a new lower bound for , and we
explain how can be computed using geometric programming. The lower
bound is generally not as good as the lower bound introduced
by Lasserre and Parrilo and Sturmfels, which is computed using semidefinite
programming, but a run time comparison shows that, in practice, the computation
of is much faster. The computation is simplest when the highest degree
term of has the form , , . The
lower bounds for established in [6] are obtained by evaluating the
objective function of the geometric program at the appropriate feasible points
Constraints on Adaptive Evolution: The functional trade-off between reproduction and fast-start swimming performance in the Trinidadian guppy (Poecilia reticulata)
The empirical study of natural selection reveals that adaptations often involve trade-offs between competing functions. Because natural selection acts on whole organisms rather than isolated traits, adaptive evolution may be constrained by the interaction between traits that are functionally integrated. Yet, few attempts have been made to characterize how and when such constraints are manifested or whether they limit the adaptive divergence of populations. Here we examine the consequences of adaptive life-history evolution on locomotor performance in the live-bearing guppy. In response to increased predation from piscivorous fish, Trinidadian guppies evolve an increased allocation of resources toward reproduction. These populations are also under strong selection for rapid fast-start swimming performance to evade predators. Because embryo development increases a female\u27s wet mass as she approaches parturition, an increased investment in reproductive allocation should impede fast-start performance. We find evidence for adaptive but constrained evolution of fast-start swimming performance in laboratory trials conducted on second-generation lab-reared fish. Female guppies from high-predation localities attain a faster acceleration and velocity and travel a greater distance during fast-start swimming trials. However, velocity and distance traveled decline more rapidly over the course of pregnancy in these same females, thus reducing the magnitude of divergence in swimming performance between high- and low-predation populations. This functional trade-off between reproduction and swimming performance reveals how different aspects of the phenotype are integrated and highlights the complexity of adaptation at the whole-organism level
Metabolic rate evolves rapidly and in parallel with the pace of life history
Metabolic rates and life history strategies are both thought to set the "pace of life", but whether they evolve in tandem is not well understood. Here, using a common garden experiment that compares replicate paired populations, we show that Trinidadian guppy (Poecilia reticulata) populations that evolved a fast-paced life history in high-predation environments have consistently higher metabolic rates than guppies that evolved a slow-paced life history in low-predation environments. Furthermore, by transplanting guppies from high- to low-predation environments, we show that metabolic rate evolves in parallel with the pace of life history, at a rapid rate, and in the same direction as found for naturally occurring populations. Together, these multiple lines of inference provide evidence for a tight evolutionary coupling between metabolism and the pace of life history
Distinguishing separable and entangled states
We show how to design families of operational criteria that distinguish
entangled from separable quantum states. The simplest of these tests
corresponds to the well-known Peres-Horodecki positive partial transpose (PPT)
criterion, and the more complicated tests are strictly stronger. The new
criteria are tractable due to powerful computational and theoretical methods
for the class of convex optimization problems known as semidefinite programs.
We successfully applied the results to many low-dimensional states from the
literature where the PPT test fails. As a byproduct of the criteria, we provide
an explicit construction of the corresponding entanglement witnesses.Comment: 4 pages, Latex2e. Expanded discussion of numerical procedures.
Accepted for publication in Physical Review Letter
On the Generation of Positivstellensatz Witnesses in Degenerate Cases
One can reduce the problem of proving that a polynomial is nonnegative, or
more generally of proving that a system of polynomial inequalities has no
solutions, to finding polynomials that are sums of squares of polynomials and
satisfy some linear equality (Positivstellensatz). This produces a witness for
the desired property, from which it is reasonably easy to obtain a formal proof
of the property suitable for a proof assistant such as Coq. The problem of
finding a witness reduces to a feasibility problem in semidefinite programming,
for which there exist numerical solvers. Unfortunately, this problem is in
general not strictly feasible, meaning the solution can be a convex set with
empty interior, in which case the numerical optimization method fails.
Previously published methods thus assumed strict feasibility; we propose a
workaround for this difficulty. We implemented our method and illustrate its
use with examples, including extractions of proofs to Coq.Comment: To appear in ITP 201
Examining Pregnant Women's Hostile Attributions About Infants as a Predictor of Offspring Maltreatment
Child maltreatment is a serious public health problem that disproportionately affects infants and toddlers. In the interest of informing prevention and intervention efforts, this study examined pregnant women’s attributions about infants as a risk factor for child maltreatment and harsh parenting during their children’s first and second years. We also provide specific methods for practitioners to assess hostile attributions
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