1,863 research outputs found
Day-Night and Energy Dependence of MSW Solar Neutrinos for Maximal Mixing
It has been stated in the literature that the case of maximal mixing angle
for \nu_e leads to no day-night effect for solar neutrinos and an energy
independent flux suppression of 1/2. While the case of maximal mixing angle and
\Delta m^2 in the MSW range does lead to suppression of the electron neutrinos
reaching the earth from the sun by P_S=1/2, the situation is different for
neutrinos that have passed through the earth. We make the pedagogical point
that, just as with smaller mixing angles, the earth regenerates the |\nu_1>
state from the predominantly |\nu_2 > state reaching the earth, leading to
coherent interference effects. This regeneration can lead to a day-night effect
and an energy dependence of the suppression of solar electron neutrinos, even
for the case of maximal mixing. For large mixing angles, the energy dependence
of the day-night asymmetry depends heavily on Delta m^2. With a sufficiently
sensitive measurement of the day-night effect, this energy dependence could be
used to distinguish among the large mixing angle solutions of the solar
neutrino problem.Comment: JHEP style, 22 pages, 7 figures. References added, and minor
rewordin
How Can Increased Parental Involvement Facilitate Greater Student Engagement and Academic Success Within One RGV Middle School
The purpose of this study is to explore how can increased parental involvement be encouraged in the K-12 school in the Rio Grande Valley in order to facilitate greater student engagement and academic success. An action research project will be done to explore middle school teachers’ perspectives on parental involvement and the effect it has on student academics. Research will take place in Sunview Middle School were interviews, observations will be conducted to teachers, parental involvement assistant and administrator. Data will assist to improve and promote the parental involvement program to assist all stakeholders and better assist our students
The Midpoint Rule as a Variational--Symplectic Integrator. I. Hamiltonian Systems
Numerical algorithms based on variational and symplectic integrators exhibit
special features that make them promising candidates for application to general
relativity and other constrained Hamiltonian systems. This paper lays part of
the foundation for such applications. The midpoint rule for Hamilton's
equations is examined from the perspectives of variational and symplectic
integrators. It is shown that the midpoint rule preserves the symplectic form,
conserves Noether charges, and exhibits excellent long--term energy behavior.
The energy behavior is explained by the result, shown here, that the midpoint
rule exactly conserves a phase space function that is close to the Hamiltonian.
The presentation includes several examples.Comment: 11 pages, 8 figures, REVTe
Subclustering and Luminous-Dark Matter Segregation in Galaxy Clusters
We have performed a series of N-body experiments on Connection Machine-5 in
order to simulate the formation of galaxy clusters gravitationally dominated by
a massive dark background. In accordance with previous authors we find an
extremely inhomogeneous evolution where subcondensations are continually formed
and merged. The final distribution of galaxies is more centrally condensed than
that of dark matter particles. We have analyzed the origin of this galaxy-dark
matter segregation and also the origin of subclustering leading to this effect.
We have then analysed, analytically and numerically, the dependence of final
segregation on the physical parameters characterizing the model of
protocluster. We also find that such a segregation persists even when inelastic
encounters of dark halos around galaxies are taken into account. We conclude
that this effect cannot be in general avoided in any hierarchical clustering
scenario.Comment: 26 pages plus 13 figures (4 of which, not included, available upon
request to [email protected]), postscript, Preprint OP-9303
Experience of Anti-VEGF Treatment and Clinical Levels of Depression and Anxiety in Patients With Wet Age-Related Macular Degeneration
PURPOSE: To investigate detailed patient experiences specific to receiving vascular endothelial growth factor inhibitors (anti-VEGF) for wet age-related macular degeneration (wAMD), and to acquire a snapshot of the frequency of clinically significant levels of depression, anxiety, and posttraumatic stress among patients and levels of burden in patients’ carers. DESIGN: Observational cross-sectional mixed-methods study. METHODS: Three hundred patients with wAMD receiving anti-VEGF treatment and 100 patient carers were recruited. Qualitative data on patients’ experience of treatment were collected using a structured survey. Standardized validated questionnaires were used to quantify clinically significant levels of anxiety, depression, and posttraumatic stress, as well as cognitive function and carers’ burden. RESULTS: Qualitative data showed that 56% of patients (n =132) reported anxiety related to antiVEGF treatment. The main sources of anxiety were fear of going blind owing to intravitreal injections and concerns about treatment effectiveness, rather than around pain. From validated questionnaires, 17% of patients (n= 52) showed clinical levels of anxiety and 12% (n =36) showed clinical levels of depression. Depression levels, but not anxiety, were significantly higher in patients who received up to 3 injections compared with patients who received from 4 to 12 injections (analysis of variance [ANOVA] P = .027) and compared with patients who received more than 12 injections (ANOVA P = .001). CONCLUSIONS: Anti-VEGF treatment is often experienced with some anxiety related to treatment, regardless of the number of injections received. Clinical levels of depression seem to be more frequent in patients at early stages of anti-VEGF treatment. Strategies to improve patient experience of treatment and minimize morbidity are suggested
Higher Order Force Gradient Symplectic Algorithms
We show that a recently discovered fourth order symplectic algorithm, which
requires one evaluation of force gradient in addition to three evaluations of
the force, when iterated to higher order, yielded algorithms that are far
superior to similarly iterated higher order algorithms based on the standard
Forest-Ruth algorithm. We gauge the accuracy of each algorithm by comparing the
step-size independent error functions associated with energy conservation and
the rotation of the Laplace-Runge-Lenz vector when solving a highly eccentric
Kepler problem. For orders 6, 8, 10 and 12, the new algorithms are
approximately a factor of , , and better.Comment: 23 pages, 10 figure
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