4,523 research outputs found
Bendito Amor: Religion and Relationships among Married and Unmarried Latinos in Urban America
The family arrangements of Latinos in the U.S. are increasingly diverse, with growing numbers of Latino children living in households headed by married and unmarried parents. Latinos also tend to be more religious than the population at large. Yet no research has examined the associations between religion and relationship quality among married and unmarried Latinos. Using data from the Fragile Families and Child Wellbeing Study, which focuses on new parents in urban America, we find that the religious attendance of Latino fathers promotes higher-quality relationships among both fathers and mothers; by contrast, the effect of maternal attendance on relationship quality is insignificant or negative.
Fast Mesh Refinement in Pseudospectral Optimal Control
Mesh refinement in pseudospectral (PS) optimal control is embarrassingly easy
--- simply increase the order of the Lagrange interpolating polynomial and
the mathematics of convergence automates the distribution of the grid points.
Unfortunately, as increases, the condition number of the resulting linear
algebra increases as ; hence, spectral efficiency and accuracy are lost in
practice. In this paper, we advance Birkhoff interpolation concepts over an
arbitrary grid to generate well-conditioned PS optimal control discretizations.
We show that the condition number increases only as in general, but
is independent of for the special case of one of the boundary points being
fixed. Hence, spectral accuracy and efficiency are maintained as increases.
The effectiveness of the resulting fast mesh refinement strategy is
demonstrated by using \underline{polynomials of over a thousandth order} to
solve a low-thrust, long-duration orbit transfer problem.Comment: 27 pages, 12 figures, JGCD April 201
Development of high-emittance scales on thoriated nickel-chromium-aluminum-base alloys
The surface regions of a DSNiCrAl alloy have been doped, by a pack diffusion process, with small amounts of Mn, Fe, or Co, and the effect of these dopants on the total normal emissivity of the scales produced by subsequent high temperature oxidation has been measured. While all three elements lead to a modest increase in emissivity, (up to 23% greater than the undoped alloy) only the change caused by manganese is thermally stable. However, this increased emissivity is within 85 percent of that of TDNiCr oxidized to form a chromia scale. The maganese-doped alloy is some 50 percent weaker than undoped DSNiCrAl after the doping treatment, and approximately 30 percent weaker after oxidation
Characterizing Entanglement via Uncertainty Relations
We derive a family of necessary separability criteria for finite-dimensional
systems based on inequalities for variances of observables. We show that every
pure bipartite entangled state violates some of these inequalities.
Furthermore, a family of bound entangled states and true multipartite entangled
states can be detected. The inequalities also allow to distinguish between
different classes of true tripartite entanglement for qubits. We formulate an
equivalent criterion in terms of covariance matrices. This allows us to apply
criteria known from the regime of continuous variables to finite-dimensional
systems.Comment: 4 pages, no figures. v2: Some discussion added, main results
unchange
Antibodies to acetylcholine receptor in parous women with myasthenia: evidence for immunization by fetal antigen
The weakness in myasthenia gravis (MG) is mediated by autoantibodies against adult muscle acetylcholine receptors (AChR) at the neuromuscular junction; most of these antibodies also bind to fetal AChR, which is present in the thymus. In rare cases, babies of mothers with MG, or even of asymptomatic mothers, develop a severe developmental condition, arthrogryposis multiplex congenita, caused by antibodies that inhibit the ion channel function of the fetal AChR while not affecting the adult AChR. Here we show that these fetal AChR inhibitory antibodies are significantly more common in females sampled after pregnancy than in those who present before pregnancy, suggesting that they may be induced by the fetus. Moreover, we were able to clone high-affinity combinatorial Fab antibodies from thymic cells of two mothers with MG who had babies with arthrogryposis multiplex congenita. These Fabs were highly specific for fetal AChR and did not bind the main immunogenic region that is common to fetal and adult AChR. The Fabs show strong biases to VH3 heavy chains and to a single Vk1 light chain in one mother. Nevertheless, they each show extensive intraclonal diversification from a highly mutated consensus sequence, consistent with antigen-driven selection in successive steps. Collectively, our results suggest that, in some cases of MG, initial immunization against fetal AChR is followed by diversification and expansion of B cells in the thymus; maternal autoimmunity will result if the immune response spreads to the main immunogenic region and other epitopes common to fetal and adult AChR
Programming and Proving with Distributed Protocols
Distributed systems play a crucial role in modern infrastructure, but are notoriously difficult to
implement correctly. This difficulty arises from two main challenges: (a) correctly implementing
core system components (e.g., two-phase commit), so all their internal invariants hold, and (b)
correctly composing standalone system components into functioning trustworthy applications (e.g.,
persistent storage built on top of a two-phase commit instance). Recent work has developed several
approaches for addressing (a) by means of mechanically verifying implementations of core distributed
components, but no methodology exists to address (b) by composing such verified components into
larger verified applications. As a result, expensive verification efforts for key system components are
not easily reusable, which hinders further verification efforts.
In this paper, we present Disel, the first framework for implementation and compositional
verification of distributed systems and their clients, all within the mechanized, foundational context
of the Coq proof assistant. In Disel, users implement distributed systems using a domain specific
language shallowly embedded in Coq and providing both high-level programming constructs as well
as low-level communication primitives. Components of composite systems are specified in Disel as
protocols, which capture system-specific logic and disentangle system definitions from implementation
details. By virtue of Disel’s dependent type system, well-typed implementations always satisfy
their protocols’ invariants and never go wrong, allowing users to verify system implementations
interactively using Disel’s Hoare-style program logic, which extends state-of-the-art techniques for
concurrency verification to the distributed setting. By virtue of the substitution principle and frame
rule provided by Disel’s logic, system components can be composed leading to modular, reusable
verified distributed systems.
We describe Disel, illustrate its use with a series of examples, outline its logic and metatheory,
and report on our experience using it as a framework for implementing, specifying, and verifying
distributed systems
Cannabis through the looking glass: chemo- and enantio-selective separation of phytocannabinoids by enantioselective ultra high performance supercritical fluid chromatography
By using the Inverted Chirality Columns Approach (ICCA) we have developed an enantioselective UHPSFC method to determine the enantiomeric excess (ee) of (-)-Δ(9)-THC in medicinal marijuana (Bedrocan®). The ee was high (99.73%), but the concentration of the (+)-enantiomer (0.135%) was not negligible, and it is worth a systematic evaluation of bioactivity
A Review of the Effects of Globalization on Nigeria Economic Development
This study suggests that Nigeria political leaders develop the political will to break away from depending on the International Capitalist system whose interest is to perpetuate the country’s peripheral states. Since independence, Nigeria has unsuccessfully tried various models aimed at achieving sustainable development. Nigerians however still pursue policies aimed at improvement of Nigerians standard of living. One of such policy is globalization which she has pursued vigorously in keeping with the demands of the International Financial Institution of the World Bank and International Monetary Fund (IMF). This work critically examines the effects of globalization on Nigeria’s economy especially within the democratic dispensation. The main feature of the current economic situations in the contemporary world system is globalization which is led by a New Age of Information Technology (IT) which is contrary to the history of human kind. Countries have continually intensified various efforts towards engaging in business across country’s borders and distributing networks and production on a global scale. Therefore, with these trends of political, economic, social and technological forces, the world is becoming a ‘global village’. Based on the above, this study recognizes the existence of a global environment that is deeply embedded in interdependency and the necessity for Nigeria to minimize the negative effects of globalization while exploring its benefits for national development and economic growth. Keywords: Globalization, Economic Development, Nigeri
Job Design Theory: School Structure, Teachers\u27 Job Characteristics and Microeconomic Resource Allocation in Classrooms
The results of this exploratory study of job design in education are encouraging
Moving system with speeded-up evolution
In the classical (non-quantum) relativity theory the course of the moving
clock is dilated as compared to the course of the clock at rest (the Einstein
dilation). Any unstable system may be regarded as a clock. The time evolution
(e.g., the decay) of a uniformly moving physical system is considered using the
relativistic quantum theory. The example of a moving system is given whose
evolution turns out to be speeded-up instead of being dilated. A discussion of
this paradoxical result is presented.Comment: 10 pages, LaTe
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