State-to-state dynamics of elementary chemical reactions using Rydberg H-atom translational spectroscopy

In this review, a few examples of state-to-state dynamics studies of both unimolecular and bimolecular reactions using the H-atom Rydberg tagging TOF technique were presented. From the H2O photodissociation at 157 nm, a direction dissociation example is provided, while photodissociation of H2O at 121.6 has provided an excellent dynamical case of complicated, yet direct dissociation process through conical intersections. The studies of the O(D-1) + H-2 --> OH+H reaction has also been reviewed here. A prototype example of state-to-state dynamics of pure insertion chemical reaction is provided. Effect of the reagent rotational excitation and the isotope effect on the dynamics of this reaction have also been investigated. The detailed mechanism for abstraction channel in this reaction has also been closely studied. The experimental investigations of the simplest chemical reaction, the H-3 system, have also been described here. Through extensive collaborations between theory and experiment, the mechanism for forward scattering product at high collision energies for the H+HD reaction was clarified, which is attributed to a slow down mechanism on the top of a quantized barrier transition state. Oscillations in the product quantum state resolved different cross sections have also been observed in the H+D-2 reaction, and were attributed to the interference of adiabatic transition state pathways from detailed theoretical analysis. The results reviewed here clearly show the significant advances we have made in the studies of the state-to-state molecular reaction dynamics.

Theoretical study on the mechanisms of some elementary reactions catalyzed by modified carbonyl cobalt

All structural geometries of intermediates, transition states and product are, optimized at HF/ LANL2DZ level under the effective core potential approximation. The potential energy profile for some elementary reactions of hydroformylation catalyzed by Co-2(CO)(6)(PH3)(2), consisting of carbonyl insertion, H-2 oxidative addition and aldehyde reductive elimination, are calculated, The transition states are further confirmed by having one and only one imaginary vibrational frequency, The activation energies of carbonyl insertion, H-2 oxidative addition and aldehyde reductive elimination are 54, 02, 134, 02 and 43. 44 kJ/mol, respectively.

High resolution time-of-flight spectrometer for crossed molecular beam study of elementary chemical reactions

In this article, we describe an apparatus in our laboratory for investigating elementary chemical reactions using the high resolution time-of-flight Rydberg tagging method. In this apparatus, we have adopted a rotating source design so that collision energy can be changed for crossed beam studies of chemical reactions. Preliminary results on the HI photodissociation and the F atom reaction with H-2 are reported here. These results suggest that the experimental apparatus is potentially a powerful tool for investigating state-to-state dynamics of elementary chemical reactions. (c) 2005 American Institute of Physics.

Sleep Patterns in Elementary School Children (Grades 2-5) and Adolescents (Grade 10)

Background: To date, there is limited research examining sleep patterns in elementary school children. Previous researchers focused on parental responses rather than student responses to determine factors that affect sleep. The presented study surveyed sleep patterns and examined external factors affecting total sleep time among elementary school children and adolescents. Methods: Students in grades 2-5 (n=885) and grade 10 (n=190) enrolled in a public school system in the Northeast, completed a district administered survey that included questions on sleep duration and hygiene. Results. Average reported sleep duration decreased with increasing grade level. Children in grades 2-5 woke up earlier (31.7-72.4%) and on their own in comparison to adolescents in grade 10 (6.8%). Significantly shorter sleep durations were associated with having a television (grades 2, 4, 5, p< 0.01) or a cell phone in the room (grades 3, 4; p < 0.05), playing on the computer or video games (grades 3, 4, p<.001) before going to bed. In contrast, students in grade 2, 3, & 4 who reported reading a book before going to bed slept on average 21 minutes more per night (p=.029, .007, .009, respectively). For tenth graders, only consumption of energy drinks led to significant reduction in sleep duration (p<.0001). Conclusion. Sleep is a fundamental aspect in maintaining a healthy and adequate life style. Understanding sleep patterns will assist parents, health care providers, and educators in promoting quality sleep hygiene in school-aged children.

Elementary Principals' Perceptions of a Leadership Development Training Program

Research indicates that school leaders are crucial to improving instruction and raising student achievement (Council of Chief State School Officers, 2008). As such, educational reforms such as the No Child Left Behind Act (2001) and Race to the Top (2009) have sparked an accountability movement where principals are being held accountable for students' academic achievement and educational outcomes. The shift towards greater accountability has placed new attention on the ways principals are trained. Researchers have noted that organized professional development programs have not adequately prepared school principals to meet the priority demands of the 21st century (Hale & Moorman, 2003; Murphy, 1994). Murphy (1994) stated, "Traditional preparation programs - usually pre-service programs based in colleges or universities, that awarded certification and advanced degrees - rarely concentrated on the leadership challenges that principals actually face in real schools" (p. 4). As a result, many school districts are seeking ways to develop leadership development training programs that will prepare principals for their job responsibilities as a school leader. In spite of the additional training principals receive, researchers suggests that there is an obvious gap between the readiness of administrators to be instructional leaders and the demands for accountability that school administrators face (Hale & Moorman, 2003). This quantitative study examined elementary school principals' perceptions of their leadership development training program. Guided by four research questions, the study examined principals' perceptions of their overall training and how well their training prepared them to deal with school and classroom practices that contribute to student achievement; to work with teachers and others to design and implement a system for continuous student achievement; and to provide necessary support to carry out sound school, curriculum, and instructional practices. Data for this study was collected by way of survey responses from a total of 46 elementary school principals. The results from the study revealed that more than half (58.7%) of participants perceived their training as excellent. While principals' perceived that their training adequately prepared them to work collaboratively in teams, set clear visions and goals, and to use data to improve students achievement, many respondents reported a lack of training in being informed and focused on student achievement. Principals also suggested that they were not effectively trained in finding effective ways to obtain support from central office or community members.

Preservice Elementary Teachers’ Beliefs toward Mathematics and Mathematics Teaching

As they began their one-year teacher education program 138 elementary school teacher candidates completed a questionnaire designed to measure their beliefs concerning the nature of mathematics, measured on a scale from absolutist to fallibilist, and their beliefs concerning effective mathematics instruction, measured on a scale from traditional to constructivist. Interviews were conducted with volunteer questionnaire participants, with selection based on the questionnaire results and using two sets of criteria. Study 1. involved 8 teacher candidates showing distinct absolutist or fallibilist views of mathematics and individual interviews explored participants' beliefs concerning the use of information and communication technology, particularly interactive whiteboards (IWB), in the teaching and learning of mathematics. Participants with absolutist beliefs about the nature of mathematics tended to focus on the IWB as a presentation tool, while those with fallibilist beliefs appreciated the use of the IWB to support student exploration. Study 2. involved 8 teacher candidates with apparently misaligning absolutist beliefs concerning the nature of mathematics and constructivist beliefs concerning teaching. Interviews exploring participants' favoured instructional approaches, particularly those involving the use of manipulatives, showed that constructivist views involved essentially surface beliefs and that in fact manipulatives would be employed to support traditional direct instruction.

Ca(2+)-sparks constitute elementary building blocks for global Ca(2+)-signals in myocytes of retinal arterioles.

Spontaneous Ca2+-events were imaged in myocytes within intact retinal arterioles (diameter < 40 mu m) freshly isolated from rat eyes. Ca2+-sparks were often observed to spread across the width of these small cells, and could summate to produce prolonged Ca2+-oscillations and contraction. Application of cyclopiazonic acid (20 mu M) transiently increased spark frequency and oscillation amplitude, but inhibited both sparks and oscillations within 60 s. Both ryanodine (100 mu M) and tetracaine (100 mu M) reduced the frequency of sparks and oscillations, while tetracaine also reduced oscillation amplitude. None of these interventions affected spark amplitude. Nifedipine, which blocks store filling independently of any action on L-type Ca2+-channels in these cells, reduced the frequency and amplitude of both sparks and oscillations. Removal of external [Ca2+] (1 mM EGTA) also reduced the frequency of sparks and oscillations but these reductions were slower in onset than those in the presence of tetracaine or cyclopiazonic acid. Cyclopiazonic acid, nifedipine and low external [Ca2+] all reduced SR loading, as indicated by the amplitude of caffeine evoked Ca2+-transients. This study demonstrates for the first time that spontaneous Ca2+-events in small arterioles of the eye result from activation of ryanodine receptors in the SR and suggests that this activation is not tightly coupled to Ca2+-influx. The data also supports a model in which Ca2+-sparks act as building blocks for more prolonged, global Ca2+-signals. (c) 2006 Elsevier Ltd. All rights reserved.