4,390 research outputs found
Strong color fields and heavy flavor production
The clustering of color sources provides a natural framework for soft
partonic interactions producing strong color fields. We study the consequences
of these color fields in the production of heavy flavor and the behavior of the
nuclear modification factor.Comment: 11 pages, 7 figures, to appear in Physical Review
NLTE analysis of Sr lines in spectra of late-type stars with new R-matrix atomic data
We investigate statistical equilibrium of neutral and singly-ionized
strontium in late-type stellar atmospheres. Particular attention is given to
the completeness of the model atom, which includes new energy levels,
transition probabilities, photoionization and electron-impact excitation
cross-sections computed with the R-matrix method. The NLTE model is applied to
the analysis of Sr I and Sr II lines in the spectra of the Sun, Procyon,
Arcturus, and HD 122563, showing a significant improvement in the ionization
balance compared to LTE line formation calculations, which predict abundance
discrepancies of up to 0.5 dex. The solar Sr abundance is log A = 2.93 \pm 0.04
dex, in agreement with the meteorites. A grid of NLTE abundance corrections for
Sr I and Sr II lines covering a large range of stellar parameters is presented.Comment: 11 pages, 7 figures, accepted for publication in Astronomy &
Astrophysic
Electron-Ion Recombination Rate Coefficients and Photoionization Cross Sections for Astrophysically Abundant Elements VI. Ni II
We present the first detailed ab initio quantum mechanical calculations for
total and state-specific recombination rate coefficients for e + Ni III --> Ni
II. These rates are obtained using a unified treatment for total electron-ion
recombination that treats the nonresonant radiative recombination and the
resonant dielectronic recombination in a self-consistent unified manner in the
close coupling approximation. Large-scale calculations are carried out using a
49-state wavefunction expansion from core configurations 3d^8, 3d^74s, and
3d^64p that permits the inclusion of prominent dipole allowed core transitions.
These extensive calculations for the recombination rates of Ni II required
hundreds of CPU hours on the Cray T90. The total recombination rate
coefficients are provided for a wide range of temperature. The state-specific
recombination rates for 532 bound states of doublet and quartet symmetries, and
the corresponding photoionization cross sections for leaving the core in the
ground state, are presented. Present total recombination rate coefficients
differ considerably from the currently used data in astrophysical models.Comment: ApJ Suppl. (submitted), 4 figure
The Reciprocal determinism of online scaffolding in sustaining a community of inquiry in physics
This study investigated the learning impact of online scafolding in sustaining a community of inquiry in Physics
instruction. The students’ a-priori e-learning activities in online discussion were used in leveraging the learning
behaviors of the students. Online learning segments were included in the process of developing classroom
tasks vis-Ă -vis with the course intended learning outcomes. This was done in a collegial, constructive and
democratic learning towards classroom efcacy through online scafolding techniques. Two sections of 34
students enrolled in NATSC1D (University Physics 1) were used in this study. A questionnaire was adopted in
determining the perceived relative magnitude of advantages of the online discussion. Pearson-r correlation
results showed a very-highly positive correlation between the students’ a-priori e-learning experiences in
online discussion and their success in online scafolding, and a highly to very-highly positive correlation to their
performance in classroom interaction, formative assessment and summative evaluations.Peer Reviewe
The students’ procedural fluency and written-mathematical explanation on constructed response tasks in physics
Peer Reviewe
Reconstructing Classroom Routines through On-line Instructional Delivery Technique
This study investigated the impact of leveraging and harnessing students’ a-priori experiences in on-line discussion as basis of integrating new ideas and information in constructing a body of knowledge cognizant to enhancing the over-all students learning. This was done in a collegial, constructive and democratic learning towards classroom efficacy through on-line instruction delivery technique. A total of 34 students enrolled in Fundamentals of Statistics was used in this study. Learning segments through virtual instruction were included in the process of developing classroom tasks vis-à -vis with the lessons’ goals and objectives. A questionnaire was adopted in determining the perceived relative magnitude of advantages of the on-line instructional delivery technique. Using Pearson-r correlation, a very-strong positive relationship was found between the students’ a-priori experiences in on-line discussion and their success in OIDT; a moderate to strong positive correlation were established between OIDT and students’ performance in formative evaluations, classroom interaction and academic performance. Key Terms: A-priori On-line Learning Experiences, Academic Performance, On-line Discussion, On-line Instructional Delivery Technique, Virtual Learning Environment
The Convergence of Mayer’s Model and Constructivist Model towards Problem solving in Physics
This study investigated the convergence of the Mayer’s model and constructivist model towards problem solving in Physics. Twenty six students in Physics 1 (University Physics 1) enrolled in the third trimester, SY 2011 – 2012, were used as subjects of the study. An analysis of the students’ learning history in College Algebra and Trigonometry was conducted as basis of determining their mathematical abilities. A pre-test was conducted to determine the initial learning schema of the respondents. The examination used as pre-test was formulated by the author as his output in his dissertation and was field tested to a group of students majoring in Science at Quirino State College, Philippines. The Mayer’s model was used as a default procedure followed by the four-stage constructivist model in problem solving. Students were engaged in active learning through direct instruction using the Mayer’s model from the teacher, small group discussion, peer mentoring and follow-up session/s by the teacher vis-à -vis with the four-stage constructivist model in problem solving. Analysis of transcripts was done to determine the extent of learning of the respondents and the remediation to be implemented. After the execution of the lessons, the students were given a post-test. It was found out that the students who were exposed to the convergence of the Mayer’s model with the constructivist model developed better attitudes and performance in problem solving. A significant effect and a moderately high impact model of variability on the attitude and academic performance of the students: 85.2 % on the students’ attitude towards problem solving and 80.00 % on the students’ academic performance. Keywords: Constructivist Model for Teaching Word Problem, Learning Attitudes, Learning Ability, Mathematical Discourse, Mayer’s Model in Problem Solvin
The Convergence of Mastery Learning Approach and Self-Regulated Learning Strategy in Teaching Biology
This study investigated the convergence of Bloom’s Mastery Learning Approach (MLA) and Bandura’s Social Cognitive Theory in Zimmerman’s Self-Regulated Learning (SRL) Strategy in increasing students’ academic performance in Biology. Fifty-two students in Biological Science enrolled in the second semester, SY 2007 – 2008, were used as subjects of the study. The Quasi-Experimental Design was used in the study: a pre-test was conducted, scored and analyzed which served as the basis in determining the initial learning schema of the respondents. After the execution of the lessons using the converging models of MLA and SRL Strategy, the students were given a post-test. It was found out that the students who were exposed to the converging teaching modalities developed better performance in Biology. ANCOVA results on the post-test mean scores of the respondents were utilized in establishing the causal-effect of the converging models to the academic performance of the students in Biology. A highly significant effect on their academic performance and significant interaction of the models to the experimental grouping and mental abilities of the respondents are concluded in the study. Keywords: Academic Performance, Bandura’s Social Cognitive Theory, Mastery Learning Approach, Self-Regulated Learning, Students’ Motivation in Science Learnin
Determinants and policy implications of drug utilization in the Philippines
The drug question has emerged as the central issue from which current health concerns in the
Philippines are hinged on. With the formulation of the National Drug Policy and the legislation
on the Generics Act, the supply of appropriate drugs --those of the right kind, quality and
quantity which can be sold at reasonable prices--has been a key strategy of the government's
health program. The highly charged discussions that accompanied the passage of the Generics
Act into law indicate that the reorganization of the drug supply system to meet the people's needs
is by no means an easy task.
Much of the arguments have focused on the gap between the health needs of Filipinos and
existing systems of pharmaceutical development, promotion, marketing and distribution. Yet,
while much is known about the latter in the works of Gabunada (1983), Sepulveda and Meneses
(1980), and Kintanar and Chanco (1979), discussions on household utilization of pharmaceuticals
have received scant attention (Hardon 1987). Studies on pharmaceuticals have concentrated on the
supply side or the industry level and little is known about the demand side. A study on drug
consumption behavior is necessary to anticipate the likely effects of policies on the users. While
policies are seen as regulations on the industry and the prescriber, it is private or household
consumption patterns that are of interest in terms of welfare. The decision algorithm of
households in relation to pharmaceuticals provides insights into general household healthseeking
behavior
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