3,478 research outputs found
Do You Always Need a Textbook to Teach Astro 101?
The increasing use of interactive learning strategies in Astro 101 classrooms
has led some instructors to consider the usefulness of a textbook in such
classes. These strategies provide students a learning modality very different
from the traditional lecture supplemented by reading a textbook and homework,
and raises the question of whether the learning that takes place during such
interactive activities is enough by itself to teach students what we wish them
to know about astronomy. To address this question, assessment data is presented
from an interactive class, which was first taught with a required textbook, and
then with the textbook being optional. Comparison of test scores before and
after this change shows no statistical difference in student achievement
whether a textbook is required or not. In addition, comparison of test scores
of students who purchased the textbook to those who did not, after the textbook
became optional, also show no statistical difference between the two groups.
The Light and Spectroscopy Concept Inventory (LSCI), a research-validated
assessment tool, was given pre- and post-instruction to three classes that had
a required textbook, and one for which the textbook was optional, and the
results demonstrate that the student learning gains on this central topic were
statistically indistinguishable between the two groups. Finally, the Star
Properties Concept Inventory (SPCI), another research-validated assessment
tool, was administered to a class for which the textbook was optional, and the
class performance was higher than that of a group of classes in a national
study
Introduction of interactive learning into French university physics classrooms
We report on a project to introduce interactive learning strategies (ILS) to
physics classes at the Universit\'e Pierre et Marie Curie (UPMC), one of the
leading science universities in France. In Spring 2012, instructors in two
large introductory classes, first-year, second-semester mechanics, and
second-year introductory E&M, enrolling approximately 500 and 250 students
respectively, introduced ILS into some sections of each class. The specific ILS
utilized were Think-Pair-Share questions and Peer Instruction in the main
lecture classrooms, and UW Tutorials for Introductory Physics in recitation
sections. Pre- and post-instruction assessments (FCI and CSEM respectively)
were given, along with a series of demographics questions. We were able to
compare the results of the FCI and CSEM between interactive and non-interactive
classes taught simultaneously with the same curriculum. We also analyzed final
exam results, as well as the results of student and instructor attitude surveys
between classes. In our analysis, we argue that Multiple Linear Regression
modeling is superior to other common analysis tools, including normalized gain.
Our results show that ILS are effective at improving student learning by all
measures used: research-validated concept inventories and final exam scores, on
both conceptual and traditional problem-solving questions. Multiple Linear
Regression analysis reveals that interactivity in the classroom is a
significant predictor of student learning, showing a similar or stronger
relationship with student learning than such ascribed characteristics as
parents' education, and achieved characteristics such as GPA and hours studied
per week. Analysis of student and instructors attitudes shows that both groups
believe that ILS improve student learning in the physics classroom, and
increases student engagement and motivation
Gauge Orbit Types for Theories with Classical Compact Gauge Group
We determine the orbit types of the action of the group of local gauge
transformations on the space of connections in a principal bundle with
structure group O(n), SO(n) or over a closed, simply connected manifold
of dimension 4. Complemented with earlier results on U(n) and SU(n) this
completes the classification of the orbit types for all classical compact gauge
groups over such space-time manifolds. On the way we derive the classification
of principal bundles with structure group SO(n) over these manifolds and the
Howe subgroups of SO(n).Comment: 57 page
A model of mentorship for students from historically underrepresented groups in STEM
Mentorship is critical to student academic success and persistence,
especially for students from historically underrepresented (HU) groups. In a
program designed to support the academic success of HU undergraduates in STEM
who wish to pursue a PhD in those fields, students experience comprehensive
support including financial aid, highly-engaged mentoring, dual faculty
mentorship, professional development workshops, and summer research
experiences. Scholars in this program, the Cal-Bridge program, consistently
report that faculty mentorship is the most impactful feature. While mentorship
was rated highly, preliminary evaluation indicated an early deficit in a sense
of community among scholars. In response, faculty professional development and
support for peer networking were implemented to expand and enhance the
relationships that support scholar success. Here we present a promising
multifaceted model of mentorship that can support the academic success of HU
undergraduates.Comment: Submitted to Understanding Interventions. 23 pages. 4 figures.
Comments welcome
Extended Red Objects and Stellar Wind Bow Shocks in the Carina Nebula
We report the results of infrared photometry on 39 extended red objects
(EROs) in the Carina Nebula, observed with the Spitzer Space Telescope. Most
EROs are identified by bright, extended 8.0 um emission, which ranges from 10''
to 40'' in size, but our sample also includes 4 EROs identified by extended 24
um emission. Of particular interest are nine EROs associated with late O or
early B-type stars and characterized by arc-shaped morphology, suggesting
dusty, stellar-wind bow shocks. These objects are preferentially oriented
towards the central regions of the Carina Nebula, suggesting that these bow
shocks are generally produced by the interactions of OB winds with the bulk
expansion of the H II region rather than high proper motion. We identify
preferred regions of mid-infrared color space occupied by our bow shock
candidates, which also contain bow shock candidates in M17 and RCW 49 but are
well-separated from polycyclic aromatic hydrocarbon emission or circumstellar
discs. Color cuts identify an additional 12 marginally-resolved bow shock
candidates, 10 of which are also associated with known late O or early B stars.
H II region expansion velocities derived from bow shock candidate standoff
distances are ~10 km/s, assuming typical H II region gas densities, comparable
to expansion velocities derived from bow shocks in M17 and RCW 49. One
candidate bow shock provides direct evidence of physical interaction between
the massive stellar winds originating in the Trumpler 15 and Trumpler 14
clusters, supporting the conclusion that both clusters are at similar
heliocentric distances.Comment: 15 pages, 7 figures, MNRAS accepted (2014 October 10
Qualitative evaluation of a physical activity-based chronic disease prevention program in a low-income, rural South African setting
Introduction: Chronic diseases, an increasing global concern, are prevalent in the low-income communities of South Africa, where rural health systems bear the double burden of infectious and chronic diseases. The Discovery Healthy Lifestyle Programme (DHLP) is a physical activity-based chronic disease prevention program that has been implemented in a low-income, rural setting in South Africa. The DHLP consists of both school- and primary healthcare clinic-based interventions for learners (Healthnutz) and adults (Live it Up), facilitated by teachers, nurses and community volunteers. The aim of this evaluation was to qualitatively assess the process by which the DHLP was implemented, identifying enabling factors and barriers.
Methods: Data were collected in target communities at schools and clinics from semi-structured focus groups of program leaders and members, teachers and community members (n=45), situational analyses of the school physical activity environment, informal community observations and informal interviews with program coordinators.
Results: The target communities faced socioeconomic and health inequalities and remained under-resourced and under-served. In spite of these and other challenges, the DHLP was well received by community members and stakeholders. It was valued by respondents for its health and psychosocial outcomes, evidenced by increased knowledge and awareness of the importance of physical activity and healthy lifestyles, and positively altered perceptions of physical activity. Program implementers believed the Live it Up component was growing, and this suggested the sustainability of the program. There were, however, some concerns about the fidelity of the Healthnutz intervention, due to timetabling difficulties. Despite this, teachers were positive about the
program and its value for their learners, staff and school. The community characteristics of being under-resourced and underserved appeared to positively influence DHLP implementation. Local government involvement in the DHLP resulted in greater ownership of the program, which enabled successful implementation.
Conclusions: This study presents a unique opportunity to assess the implementation and sustainability requirements of programs in environments of limited resources, considerable burden of infectious and chronic diseases and extensive socioeconomic challenges. The findings suggest that through enhancement of knowledge, transfer of appropriate skills and the provision of an enabling environment, participation in physical activity can be effectively promoted in a low-income, rural setting. Physical activity interventions that promote the participation and empowerment of rural communities can be feasible and accessible, thereby assisting in addressing the growing burden of chronic diseases in low-income
Contractile force is enhanced in Aortas from pendrin null mice due to stimulation of angiotensin II-dependent signaling.
Pendrin is a Cl-/HCO3- exchanger expressed in the apical regions of renal intercalated cells. Following pendrin gene ablation, blood pressure falls, in part, from reduced renal NaCl absorption. We asked if pendrin is expressed in vascular tissue and if the lower blood pressure observed in pendrin null mice is accompanied by reduced vascular reactivity. Thus, the contractile responses to KCl and phenylephrine (PE) were examined in isometrically mounted thoracic aortas from wild-type and pendrin null mice. Although pendrin expression was not detected in the aorta, pendrin gene ablation changed contractile protein abundance and increased the maximal contractile response to PE when normalized to cross sectional area (CSA). However, the contractile sensitivity to this agent was unchanged. The increase in contractile force/cross sectional area observed in pendrin null mice was due to reduced cross sectional area of the aorta and not from increased contractile force per vessel. The pendrin-dependent increase in maximal contractile response was endothelium- and nitric oxide-independent and did not occur from changes in Ca2+ sensitivity or chronic changes in catecholamine production. However, application of 100 nM angiotensin II increased force/CSA more in aortas from pendrin null than from wild type mice. Moreover, angiotensin type 1 receptor inhibitor (candesartan) treatment in vivo eliminated the pendrin-dependent changes contractile protein abundance and changes in the contractile force/cross sectional area in response to PE. In conclusion, pendrin gene ablation increases aorta contractile force per cross sectional area in response to angiotensin II and PE due to stimulation of angiotensin type 1 receptor-dependent signaling. The angiotensin type 1 receptor-dependent increase in vascular reactivity may mitigate the fall in blood pressure observed with pendrin gene ablation
A Distance-Limited Imaging Survey of Sub-Stellar Companions to Solar Neighborhood Stars
We report techniques and results of a Palomar 200-inch (5 m) adaptive optics
imaging survey of sub-stellar companions to solar-type stars. The survey
consists of Ks coronagraphic observations of 21 FGK dwarfs out to 20 pc (median
distance about 17 pc). At 1-arcsec separation (17 projected AU) from a typical
target system, the survey achieves median sensitivities 7 mag fainter than the
parent star. In terms of companion mass, that corresponds to sensitivities of
50MJ (1 Gyr), 70MJ (solar age), and 75MJ (10 Gyr), using the evolutionary
models of Baraffe and colleagues. Using common proper motion to distinguish
companions from field stars, we find that no system shows positive evidence of
a previously unknown substellar companion (searchable separation about 20-250
projected AU at the median target distance).Comment: 29 pages, 5 figures. Carson et al. 2008, AJ, in pres
Evaluation of a school-based physical activity intervention in Alexandra Township
Objectives. Non-communicable diseases and limited participation in school physical education have become increasing concerns in South Africa. In response to these concerns, a schoolbased physical activity intervention, Healthnutz, was implemented in three primary schools in Alexandra Township, Johannesburg. Evaluation of Healthnutz included assessing its feasibility and acceptability, and short-term changes in learners’ physical fitness, knowledge and attitudes. Methods. To assess feasibility and acceptability, a situational analysis and focus groups with teachers and programme monitors were conducted. Pre-post fitness testing (3-month interval) was conducted with learners, and a questionnaire assessed changes in learners’ knowledge, attitudes, self-efficacy, and perceived barriers to physical activity, in control and intervention schools. Results. At implementation, teachers identified the need for more physical activity in the school environment and were positive about Healthnutz. Follow-up focus group discussions suggested that it was positively impacting teachers, learners and the school in general. Scores for sit and reach (p<0.001), sit ups (p<0.02) and shuttle run (p<0.0001) improved significantly in intervention but not control schools. A significant decrease was observed in learners’ perceived external barriers to physical activity (p<0.0001) along with a positive change in learners’ self-efficacy for physical activity (p<0.05). Conclusions. Healthnutz raised awareness of the importance of physical activity in intervention schools. Findings indicate that even limited exposure to a physical activity intervention can lead to a significant improvement in aspects of learners’ fitness, knowledge, attitudes and perceptions regarding physical activity. Furthermore, training and support of teachers needs to be nonjudgemental and empowering
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