1,562 research outputs found
Providing True Opportunity for Opportunity Youth: Promising Practices and Principles for Helping Youth Facing Barriers to Employment
Many "opportunity youth" -- youth who are not working or in school -- would benefit substantially from gaining work experience but need help overcoming barriers to employment and accessing the labor market.Those opportunity youth facing the most significant challenges, such as extreme poverty, homelessness, and justice system involvement, often need even more intensive assistance in entering and keeping employment, and are at risk of being left behind even by employment programs that are specifically designed to serve opportunity youth.This paper builds on the research literature with extensive interviews with employment program providers who have had success in helping the most vulnerable opportunity youth succeed in the workforce. Six principles for effectively serving these youth are identified
Timing of the 2008 Outburst of SAX J1808.4-3658 with XMM-Newton: A Stable Orbital Period Derivative over Ten Years
We report on a timing analysis performed on a 62-ks long XMM-Newton
observation of the accreting millisecond pulsar SAX J1808.4-3658 during the
latest X-ray outburst that started on September 21, 2008. By connecting the
time of arrivals of the pulses observed during the XMM observation, we derived
the best-fit orbital solution and a best-fit value of the spin period for the
2008 outburst. Comparing this new set of orbital parameters and, in particular,
the value of the time of ascending-node passage with the orbital parameters
derived for the previous four X-ray outbursts of SAX J1808.4-3658 observed by
the PCA on board RXTE, we find an updated value of the orbital period
derivative, which turns out to be s/s. This new value of the orbital period derivative agrees with the
previously reported value, demonstrating that the orbital period derivative in
this source has remained stable over the past ten years. Although this timespan
is not sufficient yet for confirming the secular evolution of the system, we
again propose an explanation of this behavior in terms of a highly
non-conservative mass transfer in this system, where the accreted mass (as
derived from the X-ray luminosity during outbursts) accounts for a mere 1% of
the mass lost by the companion.Comment: 4 pages, 3 figures. Final version, including editing corrections, to
appear on A&A Letter
Neutrinos and Big-Bang Nucleosynthesis
Observations of clusters and super clusters of galaxies have indicated that
the Universe is more dominated by baryons than ever estimated in the
homogeneous cosmological model for primordial nucleosynthesis. Recent
detections of possibly low deuterium abundance in Lyman- clouds along
the line of sight to high red-shift quasars have raised another potential
difficulty that \he4 is overproduced in any cosmological models which satisfy
the low deuterium abundance constraint. We show that the inhomogeneous
cosmological model with degenerate electron-neutrino can resolve these two
difficulties.Comment: 7 pages, latex, 3 figures. To appear in Nucl. Phys. A62
Public Opinion about Punishment and Corrections
Get tough control policies in the United States are often portrayed as the reflection of the public\u27s will: Americans are punitive and want offenders locked up. Research from the past decade both reinforces and challenges this assessment. The public clearly accepts, if not prefers, a range of punitive policies (e.g., capital punishment, three-strikes-and-you\u27re-out laws, imprisonment). But support for get-tough policies is mushy. Thus citizens may be willing to substitute a sentence of life imprisonment without parole for the death penalty. Especially when nonviolent offenders are involved, there is substantial support for intermediate sanctions and for restorative justice. Despite three decades of criticism, rehabilitation-particularly for the young-remains an integral part of Americans\u27 correctional philosophy. There is also widespread support for early intervention programs. In the end, the public shows a tendency to be punitive and progressive, wishing the correctional system to achieve the diverse missions of doing justice, protecting public safety, and reforming the wayward
Packing While Traveling: Mixed Integer Programming for a Class of Nonlinear Knapsack Problems
Packing and vehicle routing problems play an important role in the area of
supply chain management. In this paper, we introduce a non-linear knapsack
problem that occurs when packing items along a fixed route and taking into
account travel time. We investigate constrained and unconstrained versions of
the problem and show that both are NP-hard. In order to solve the problems, we
provide a pre-processing scheme as well as exact and approximate mixed integer
programming (MIP) solutions. Our experimental results show the effectiveness of
the MIP solutions and in particular point out that the approximate MIP approach
often leads to near optimal results within far less computation time than the
exact approach
Effect of Amino Acid Formulation and Dietary Direct-Fed Microbial Supplementation on Egg Production and Egg Characteristics in Laying Hens
An experiment was conducted to determine whether direct-fed microbial supplementation could alleviate a marginal amino acid (AA) deficiency in Hyline 36 laying hens from 33 to 44 wk of age. The experiment was a 2 × 4 factorial design with or without a commercial directfed microbial (Primilac; 1.36 kg/1,000 kg) and 4 levels of AA formulation. Egg characteristics (yolk, albumen, or shell proportions and yolk or albumen solids) were not affected by diet. Primilac supplementation had no effect on egg production or egg mass. However, Primilac supplementation reduced feed intake-to-egg mass ratio by 2.4 and 3.4% from 33 to 36 wk and 41 to 44 wk, respectively. Total eggs laid and egg mass were greatest when at least 14.4 g of CP, 804 mg of Lys, 382 mg of Met, 601 mg of TSAA, 502 mg of Thr, and 609 mg of Ile were consumed per hen per day from 33 to 44 wk of age. In conclusion, Primilac supplementation was not able to completely alleviate a marginal AA deficiency in laying hens but did improve feed intake-to-egg mass ratios during 8 wk of the 12-wk study
Detection of a period decrease in NN Ser with ULTRACAM: evidence for strong magnetic braking or an unseen companion?
We present results of high time resolution photometry of the eclipsing
pre-cataclysmic variable NN Ser. We observed 13 primary eclipses of NN Ser
using the high-speed CCD camera ULTRACAM and derived times of mid-eclipse, from
fitting of light curve models, with uncertainties as low as 0.06 s. The
observed rates of period change appear difficult to reconcile with any models
of orbital period change. If the observed period change reflects an angular
momentum loss, the average loss rate is consistent with the loss rates (via
magnetic stellar wind braking) used in standard models of close binary
evolution, which were derived from observations of much more massive cool
stars. Observations of low-mass stars such as NN Ser's secondary predict rates
of ~100 times lower than we observe. We show that magnetic activity-driven
changes in the quadrupole moment of the secondary star (Applegate, 1992) fail
to explain the period change by an order of magnitude on energetic grounds, but
that a light travel time effect caused by the presence of a third body in a
long (~ decades) orbit around the binary could account for the observed changes
in the timings of NN Ser's mid-eclipses. We conclude that we have either
observed a genuine angular momentum loss for NN Ser, in which case our
observations pose serious difficulties for the theory of close binary
evolution, or we have detected a previously unseen low-mass companion to the
binary.Comment: 10 pages, 6 figures. Accepted for publication in MNRA
- …