4,623 research outputs found
Advances in Modeling of Scanning Charged-Particle-Microscopy Images
Modeling artificial scanning electron microscope (SEM) and scanning ion
microscope images has recently become important. This is because of the need to
provide repeatable images with a priori determined parameters. Modeled
artificial images are highly useful in the evaluation of new imaging and
metrological techniques, like image-sharpness calculation, or drift-corrected
image composition (DCIC). Originally, the NIST-developed artificial image
generator was designed only to produce the SEM images of gold-on-carbon
resolution sample for image-sharpness evaluation. Since then, the new improved
version of the software was written in C++ programming language and is in the
Public Domain. The current version of the software can generate arbitrary
samples, any drift function, and many other features. This work describes
scanning in charged-particle microscopes, which is applied both in the
artificial image generator and the DCIC technique. As an example, the
performance of the DCIC technique is demonstrated.Comment: 9 pages, 6 figure
Multicritical Symmetry Breaking and Naturalness of Slow Nambu-Goldstone Bosons
We investigate spontaneous global symmetry breaking in the absence of Lorentz
invariance, and study technical Naturalness of Nambu-Goldstone (NG) modes whose
dispersion relation exhibits a hierarchy of multicritical phenomena with
Lifshitz scaling and dynamical exponents . For example, we find NG modes
with a technically natural quadratic dispersion relation which do not break
time reversal symmetry and are associated with a single broken symmetry
generator, not a pair. The mechanism is protected by an enhanced `polynomial
shift' symmetry in the free-field limit.Comment: 5 pages, 1 figure; v2: minor typos corrected, references adde
Food preferences of the commercial fishes of the Volta lake
The food of fish of the Volta in Ghana during the first two years of its existance has been described briefly by Petr(1967)detailed food analyses are being prepared for pu blicatio
Orbits and masses in the young triple system TWA 5
We aim to improve the orbital elements and determine the individual masses of
the components in the triple system TWA 5.
Five new relative astrometric positions in the H band were recorded with the
adaptive optics system at the Very Large Telescope (VLT). We combine them with
data from the literature and a measurement in the Ks band. We derive an
improved fit for the orbit of TWA 5Aa-b around each other. Furthermore, we use
the third component, TWA 5B, as an astrometric reference to determine the
motion of Aa and Ab around their center of mass and compute their mass ratio.
We find an orbital period of 6.03+/-0.01 years and a semi-major axis of
63.7+/-0.2 mas (3.2+/-0.1 AU). With the trigonometric distance of 50.1+/-1.8
pc, this yields a system mass of 0.9+/-0.1 Msun, where the error is dominated
by the error of the distance. The dynamical mass agrees with the system mass
predicted by a number of theoretical models if we assume that TWA5 is at the
young end of the age range of the TW Hydrae association.
We find a mass ratio of M_Ab / M_Aa = 1.3 +0.6/-0.4, where the less luminous
component Ab is more massive. This result is likely to be a consequence of the
large uncertainties due to the limited orbital coverage of the observations.Comment: 9 pages, 8 figures, accepted by Astronomy and Astrophysic
Hadwiger number of graphs with small chordality
The Hadwiger number of a graph G is the largest integer h such that G has the
complete graph K_h as a minor. We show that the problem of determining the
Hadwiger number of a graph is NP-hard on co-bipartite graphs, but can be solved
in polynomial time on cographs and on bipartite permutation graphs. We also
consider a natural generalization of this problem that asks for the largest
integer h such that G has a minor with h vertices and diameter at most . We
show that this problem can be solved in polynomial time on AT-free graphs when
s>=2, but is NP-hard on chordal graphs for every fixed s>=2
Anatomy of nuclear matrix elements for neutrinoless double-beta decay
We show that, within the Quasiparticle Random Phase Approximation (QRPA) and
the renormalized QRPA (RQRPA) based on the Bonn CD nucleon-nucleon interaction,
the competition between the pairing and the neutron-proton particle-particle
and particle-hole interactions causes contributions to the neutrinoless
double-beta decay matrix element to nearly vanish at internucleon distances of
more than 2 or 3 fermis. As a result, the matrix element is more sensitive to
short-range/high-momentum physics than one naively expects. We analyze various
ways of treating that physics and quantify the uncertainty it produces in the
matrix elements, with three different treatments of short-range correlations.Comment: Version to appear in Phys. Rev.
Group Care of Children and Adolescents
This literature review sought the answers to three questions regarding group care for children and adolescents:
Question 1: Is there empirical literature that supports the "best practices" idea that family foster care is better than group home care? According to the review, the answer to this question is a "strong yes." The empirical base found family foster care significantly more effective on a number of outcomes with a variety of groups of children.
Question 2: Is there empirical literature that says certain types of children do better in group homes than in family foster homes? No well-designed studies were located to answer this question conclusively. However, the author discussed studies conducted with high risk chronic juvenile offenders and reasoned that if chronic juvenile offenders can be better served in family foster care than in group care, it stands to reason that the same is true of other high-risk children with similar problems.
Question 3: If group homes might be better for some children, or if we are always going to have group homes due to "nowhere else to go," which types of group homes programs (treatment models) have shown to be effective for which types of children? Few outcome studies were found that used a rigorous research method to show program curriculums that were effective. The author cites 5 models of group home programming; 4 models show promise and include the Teaching Family Model (Kirigan, 2001); Father Flanagan's Boy's Home Model (Thompson, Smith, Oswood Dowd, Friman, & Daly, 1996); The REPARE model (Landsman, Groza, Tyler, & Molone, 2001); and "Schema" (Bass, Dosser, & Powerll, 2000). "Positive Peer Culture" was identified as an ineffective approach by former recipients in the juvenile correctional system (Kapp, 2000).
References:
1.Bass, L., Dosser, D., Powerll, J. (2000). Celebrating change: A schema for family-centered practice in residential settings. Residential Treatment for Children & Youth, 17, 123-137.
2. Landsman, M., Groza, V., Tyler, M., and Malone, K. (2001). Outcomes of family centered residential treatment. Child Welfare League of America, 50, 351-378.
3. Kapp, S. (2000). Positive Peer Culture: The viewpoint of former clients. Journal of Adolescent Group Therapy, 10, 175-189.
4.Kirigin, K. (2001). The teaching family model: A replicable system of care. Residential Treatment for Children & Youth, 18, 99-110.
5.Thompson, R., Smith G., Oswood D., Dowd T., Friman P., & Daly D. (1996). Residential care: A study of short and long-term educational effects. Children and Youth Services, 18, 221-241.c. 2002 State of Kansas Department of Social and Rehabilitation Services
May be reproduced in original
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Inpatient Treatment of Children and Adolescents
The report reviews the literature from 1975 to 2001. Conclusions from the report indicate that parental involvement is highly correlated with successful outcomes. Length of stay is not correlated with successful outcomes. Generally, extended hospitalizations provide little added benefit over shorter inpatient programs. Follow-up with community mental health is highly correlated with successful outcomes and is an integral part of maintaining goals. The therapeutic alliance is positively correlated with successful outcomes. Placement may exacerbate the sense of failure and anger, and create a sense of loss of connectedness to the family. Inpatient and residential treatment does not seem any more effective than day treatment, multi-systemic treatment, or community mental health services and is more costly. Inpatient care is generally thought of as a part of a comprehensive treatment program that includes continued treatment as an outpatient following discharge from the inpatient facility. Programs should include a focus on family involvement and establishing good therapeutic alliances. Extended hospitalization should be avoided in favor of intense community-based support and treatment, supported by brief inpatient hospitalizations with coordinated aftercare.c. 2001 State of Kansas Department of Social and Rehabilitation Services May be
reproduced in original for
One-loop counterterms for the dimensional regularization of arbitrary Lagrangians
We present master formulas for the divergent part of the one-loop effective
action for an arbitrary (both minimal and nonminimal) operators of any order in
the 4-dimensional curved space. They can be considered as computer algorithms,
because the one-loop calculations are then reduced to the simplest algebraic
operations. Some test applications are considered by REDUCE analytical
calculation system.Comment: 39 pages, Latex, 3 PS figures, replaced with published versio
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