San Diego State University

About: San Diego State University is a education organization based out in San Diego, California, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 12418 authors who have published 27950 publications receiving 1192375 citations. The organization is also known as: SDSU & San Diego State College.

197 candidates and 104 validated planets in K2's first five fields

Abstract: We present 197 planet candidates discovered using data from the first year of the NASA K2 mission (Campaigns 0-4), along with the results of an intensive program of photometric analyses, stellar spectroscopy, high-resolution imaging, and statistical validation. We distill these candidates into sets of 104 validated planets (57 in multi-planet systems), false positives, and 63 remaining candidates. Our validated systems span a range of properties, with median values of RP= 2.3 R⊕, P = 8.6 days, Teff = 5300 K, and Kp = 12.7mag. Stellar spectroscopy provides precise stellar and planetary parameters for most of these systems. We show that K2 has increased by 30% the number of small planets known to orbit moderately bright stars (1-4 R R⊕, Kp = 9-13 mag). Of particular interest are planets smaller than 2 R⊕, orbiting stars brighter than Kp = 11.5 mag, 5 receiving Earth-like irradiation levels, and several multi-planet systems - including 4 planets orbiting the M dwarf K2-72 near mean-motion resonances. By quantifying the likelihood that each candidate is a planet we demonstrate that our candidate sample has an overall false positive rate of 15%-30%, with rates substantially lower for small candidates ( 8 R⊕ and/or with P<3 days. Extrapolation of the current planetary yield suggests that K2 will discover between 500 and 1000 planets in its planned four-year mission, assuming sufficient follow-up resources are available. Efficient observing and analysis, together with an organized and coherent follow-up strategy, are essential for maximizing the efficacy of planet-validation efforts for K2, TESS, and future large-scale surveys.

Reliability and validity of the instrument used in BRFSS to assess physical activity.

Abstract: Introduction: State-level statistics of adherence to the physical activity objectives in Healthy People 2010 are derived from the Behavioral Risk Factor Surveillance System (BRFSS) data. BRFSS physical activity questions were updated in 2001 to include domains of leisure time, household, and transportation-related activity of moderate- and vigorous intensity, and walking questions. This article reports the reliability and validity of these questions. Methods: The BRFSS Physical Activity Study (BPAS) was conducted from September 2000 to May 2001 in Columbia, SC. Sixty participants were followed for 22 d; they answered the physical activity questions three times via telephone, wore a pedometer and accelerometer, and completed a daily physical activity log for 1 wk. Measures for moderate, vigorous, recommended (i.e., met the criteria for moderate or vigorous), and strengthening activities were created according to Healthy People 2010 operational definitions. Reliability and validity were assessed using Cohen's kappa ([kappa]) and Pearson correlation coefficients. Results: Seventy-three percent of participants met the recommended activity criteria compared with 45% in the total U.S. population. Test-retest reliability ([kappa]) was 0.35-0.53 for moderate activity, 0.80-0.86 for vigorous activity, 0.67-0.84 for recommended activity, and 0.85-0.92 for strengthening. Validity ([kappa]) of the survey (using the accelerometer as the standard) was 0.17-0.22 for recommended activity. Validity ([kappa]) of the survey (using the physical activity log as the standard) was 0.40-0.52 for recommended activity. Conclusions: The validity and reliability of the BRFSS physical activity questions suggests that this instrument can classify groups of adults into the levels of recommended and vigorous activity as defined by Healthy People 2010. Repeated administration of these questions over time will help to identify trends in physical activity.

Processing and properties of titanium–titanium boride (TiBw) matrix composites—a review

Abstract: Although titanium (Ti) alloys possess desirable properties such as specific strength, corrosion resistance and low density, their low specific stiffness and wear resistance have restricted their widespread application. Recently, composite strategies have provided means for overcoming these limitations. Titanium boride (TiBw) in-situ whisker reinforcements are currently recognized as one of the most compatible and effective reinforcements for Ti. This paper provides an overview of recent activities in this evolving area of Ti–TiB composites, covering processing, properties and potential applications.

Math Anxiety in Second and Third Graders and Its Relation to Mathematics Achievement

Abstract: Although the detrimental effects of math anxiety in adults are well understood, few studies have examined how it affects younger children who are beginning to learn math in a formal academic setting. Here, we examine the relationship between math anxiety and math achievement in 2nd and 3rd graders. In response to the need for a grade-appropriate measure of assessing math anxiety in this group we first describe the development of Scale for Early Mathematics Anxiety (SEMA), a new measure for assessing math anxiety in 2nd and 3rd graders that is based on the Math Anxiety Rating Scale. We demonstrate the construct validity and reliability of the SEMA and use it to characterize the effect of math anxiety on standardized measures of math abilities, as assessed using the Wechsler Individual Achievement Test (WIAT-II). Math achievement, as measured by the WIAT-II Math Composite score, was significantly and negatively correlated with SEMA but not with trait anxiety scores. Additional analyses showed that SEMA scores were significantly correlated with scores on the Math Reasoning subtest, which involves more complex verbal problem solving, but not with the Numerical Operations subtest which assesses basic computation skills. Our results suggest that math anxiety has a pronounced effect on more demanding calculations. Our results further suggest that math anxiety has an equally detrimental impact on math achievement regardless of whether children have an anxiety related to numbers or to the situational and social experience of doing math. Critically, these effects were unrelated to trait anxiety, providing the first evidence that the specific effects of math anxiety can be detected in the earliest stages of formal math learning in school. Our findings provide new insights into the developmental origins of math anxiety, and further underscore the need to remediate math anxiety and its deleterious effects on math achievement in young children.

Long-Term Effects of a Physical Education Curriculum and Staff Development Program: SPARK

Abstract: This 4-year study, conducted in seven elementary schools assigned to three conditions—Physical Education Specialists (PES), Trained Classroom Teachers (TT), and Controls (CO)—had two parts. The first investigated effects of a health-related physical education program on quantity and quality of lessons. Specialists produced the best outcomes, and TT were significantly better than nontrained peers. Part Two assessed maintenance effects approximately 1.5 years after intervention termination. Withdrawal of specialists significantly reduced the quantity and quality of physical education. TT maintained PES frequency but with a loss in lesson quality and a decline in student activity to 88% of intervention levels. Results support employing specialists and demonstrate the need for extensive professional development for classroom teachers responsible for physical education.