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-à-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 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

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

Customized Wireless Mesh Routing Metric for Swarm of Drones Applications

With the proliferation of drones applications, there is an increasing need for handling their numerous challenges. One of such challenges arises when a swarm-of-drones is deployed to accomplish a specific task which requires coordination and communication. While this swarm-of-drones is essentially a special form of mobile ad hoc networks (MANETs) which has been studied for many years, there are still some unique requirements of drone applications that necessitates re-visiting MANET approaches. These challenges stem from 3-D environments the drones are deployed in, and their specific way of mobility which adds to the wireless link management challenges. In this thesis, we consider the existing 802.11s wireless mesh standard and adopt its routing capabilities for swarm-of-drones. Specifically, we propose two link quality routing metrics called SrFTime and CRP metrics as an improvement to the 802.11s default Airtime routing metric, to enable better network throughput for drone applications. SrFTime improve network performance of stationary and mobile Wireless Mesh Networks, while CRP is designed to fit the link characteristics of drones and enable more efficient routes from these to their gateway. The evaluations in the actual 802.11s standard indicate that our proposed metrics outperforms the existing one consistently under various conditions