The mass of the black hole in LMC X-3

New high resolution, optical spectroscopy of the high mass X-ray binary LMC X-3, shows the spectral type of the donor star changes with phase due to irradition by the X-ray source. We find the spectral type is likely to be B5V, and only appears as B3V when viewing the heated side of the donor. Combining our measurements with those previously published, and taking into account the effects of X-ray irradiation, results in a value for the donor star radial velocity semi-amplitude of $K_{o} = 256.7 \pm 4.9$~km~s$^{-1}$. We find the mass of the black hole lies in the range $9.5M_{\odot} \leq M_{\rm x} \leq 13.6M_{\odot}$

Characteristics of Magnetohydrodynamic Oscillations Observed with Michelson Doppler Imager

We report on the spatial distribution of magnetogram oscillatory power and phase angles between velocity and magnetogram signals as observed with the Michelson Doppler Imager. The dataset is 151.25 arcsec times 151.25 arcsec containing sunspot from Dec 2, 1997 with a temporal sampling interval of 60 seconds and spatial sampling of 0.605 arcsec. Simultaneously observed continuum intensity and surface velocity accompany the magnetic information. We focus on three frequency regimes: 0.5-1.0, 3.0-3.5 and 5.5-6.0 mHz corresponding roughly to timescales of magnetic evolution, p-modes and the 3 minute resonant sunspot oscillation. Significant low frequency magnetogram power is found in lower flux pixels, 100-300 Gauss, in a striking ring with filamentary structure surrounding sunspot. Five minute magnetogram power peaks in extended regions of flux 600-800 Gauss. The 3 minute oscillation is observed in sunspot umbra in pixels whose flux measures 1300-1500 Gauss. Phase angles of approximately -90 degrees between velocity and magnetic flux in the 3.0-3.5 and 5.5-6.0 mHz regimes are found in regions of significant cross amplitude.Comment: 4 Pages, 4 Figures -- For better Figure files see: http://www.astro.ucla.edu/~norton/pub_list.htm

High mass X-ray binaries in the NIRorbital solutions of two highly obscured systems

The maximum mass of a neutron star (NS) is poorly defined. Theoretical attempts to define this mass have thus far been unsuccessful. Observational results currently provide the only means of narrowing this mass range down. Eclipsing X-ray binary (XRB) pulsar systems are the only interacting binaries in which the mass of the NS may be measured directly. Only 10 such systems are known to exist, 6 of which have yielded NS masses in the range 1.06 - 1.86 M$_{\odot}$.We present the first orbital solutions of two further eclipsing systems, OAO 1657-415 and EXO 1722-363, whose donor stars have only recently been identified. Using observations obtained using the VLT/ISAAC NIR spectrograph, our initial work was concerned with providing an accurate spectral classification of the two counterpart stars, leading to a consistent explanation of the mechanism for spin period evolution of OAO 1657-415. Calculating radial velocities allowed orbital solutions for both systems to be computed. These are the first accurate determinations of the NS and counterpart masses in XRB pulsar systems to be made employing NIR spectroscopy.Comment: 5 pages, 3 figures, contribution to the proceedings of "The multi-wavelength view of hot, massive stars", 39th Li`ege Int. Astroph. Coll., 12-16 July 201

A Structural Equation Model of the Influence of Personal, Behavioral, and Environmental Factors on the Writing Performance of First-year Students at a Selected Michigan Community College

Problem. While previous writing performance studies have examined a range of motivational variables such as self-efficacy or writing apprehension, certain contextual variables and variables related to current writing pedagogy and practice have not been included, which has resulted in gaps in the research literature. Method. A non-experimental, correlational, cross-sectional, ex post facto, survey research design was used to examine the personal, behavioral, and environmental factors that had been identified as being of potential influence to students’ writing performance. A census was conducted among the 233 students enrolled in English Composition on the two campuses of a small two-year college in Michigan. The final sample consisted of 125 participants enrolled in 14 sections of a first-semester Freshman English course. Instrumentation for this study consisted of three questionnaires: The Writing Survey (TWS), the Writing Tasks Scale (WTS), and three researcher-developed measures, The Student Information Form (SIF), and two survey record reviews, the Previous Writing Achievement Spreadsheet (PWAS), and the Writing Performance Spreadsheet (WPS). The Statistical Package for the Social Sciences (SPSS) was used to store and organize the data, and generate descriptive statistics. The research hypothesis was tested using structural equation modeling (SEM) with IBM SPSS Amos 21 (Arbuckle, 2012). Results. Structural equation modeling hypothesis-testing procedures indicated an acceptable fit between the theoretical covariance matrix and the observed covariance matrix. The chi-square test of the model was not statistically significant χ2 (33, N = 125) = 41.11, p = .157, which in SEM indicates that the model fits the data. The model yielded acceptable fit indices for all indices except one. The other fit measures attained the recommended target values. The value of the GFI was .94, which indicates a good fit. The NFI was .80, which is below the target value of .95. The CFI was .95, and the RMSEA was .045. The null hypothesis was therefore retained, indicating empirical support for the theoretical model. Non-significant correlations were found between Personal Factors (PF) and Environmental Factors (EF), r = .29, p = .359, Behavioral Factors (BF) and Environmental Factors (EF), r = .29, p = .325, and Personal Factors (PF) and Behavioral Factors (BF), r = .19, p = .105. Personal Factors (PF) was the only significant predictor of writing performance. The path coefficient of .26 indicated a large effect size (\u3e .25, Kieth, 2006). Writing performance was influenced by the direct effect of Personal Factors (PF), which accounted for approximately 7% of the variance in writing performance. Conclusions. The theoretical model of writing performance was supported by the findings. In addition, the causal contribution of Personal Factors, consisting of previous writing achievement, self-regulatory efficacy, and self-efficacy for writing tasks to first-year composition students’ writing performance was validated, achieving both statistical and practical significance. Overall, the findings point to the important predictive role of personal factors in students’ writing performance. The findings of this exploratory study hold implications for classroom practice, and point to the necessity of continued interdisciplinary writing research

Can Carbon Find a Home on the Range?

Resource /Energy Economics and Policy,

Feeling Good about Giving: The Benefits (and Costs) of Self-Interested Charitable Behavior

In knowledge-intensive settings such as product or software development, fluid teams of individuals with different sets of experience are tasked with projects that are critical to the success of their organizations. Although building teams from individuals with diverse prior experience is increasingly necessary, prior work examining the relationship between experience and performance fails to find a consistent effect of diversity in experience on performance. The problem is that diversity in experience improves a team's information processing capacity and knowledge base, but also creates coordination challenges. We hypothesize that team familiarity - team members' prior experience working with one another - is one mechanism that helps teams leverage the benefits of diversity in team member experience by alleviating coordination problems that diversity creates. We use detailed project- and individual-level data from an Indian software services firm to examine the effects of team familiarity and diversity in experience on performance for software development projects. We find the interaction of team familiarity and diversity in experience has a complementary effect on a project being delivered on time and on budget. In team familiarity, we identify one mechanism for capturing the performance benefits of diversity in experience and provide insight into how the management of experience accumulation affects team performance.Diversity, Experience, Knowledge, Software, Team Familiarity

Changes in Physical Activity Behaviour and Health Risk Factors Following a Randomised Controlled Pilot Workplace Exercise Intervention

Background: Declining physical activity (PA) and associated health risk factors are well established. Workplace strategies to increase PA may be beneficial to ameliorate extensive sedentary behavior. This study assessed the effectiveness of two PA interventions in workplace settings. Methods: Interventions were conducted over 40 days targeting insufficiently active (<150 min/wk PA) and/or obese (BMI ≥ 30 kg/m2) adults; participants were randomly allocated to instructor-led exercise sessions either after-work (n = 25) or in-work (n = 23) with a 60 minPA/day common goal, or a wait-listed control group (n = 23). The programme commenced with low-moderate physical activities and progressed to high intensity game style activities by week six. Adherence and compliance were determined using both objective measures of daily PA time from HR monitors and self-report responses to PA questionnaires. Cardiovascular and metabolic risk factors were measured pre- and post-intervention. Changes across the study were analysed using Chi square and repeat-measures ANOVA. Results: Adherence rates (completed pre and post-testing) were not different between groups (76.0 vs 65.2%). Compliance for the instructor-led sessions was higher for the after-work group (70.4% vs 26.4%, respectively). Increased total PA and aerobic fitness, and decreased weight in both intervention groups were found relative to controls. The after-work group undertook more vigorous PA, and had greater weight loss and fasting blood glucose improvement, relative to in-work participants and controls. Conclusions: These workplace interventions resulted in rapid and dramatic increases in PA behaviour and important health benefits. Short, in-work PA sessions were less efficacious than longer after-work sessions

Newtonian Counterparts of Spin 2 Massless Discontinuities

Massive spin 2 theories in flat or cosmological ($\Lambda \ne 0$) backgrounds are subject to discontinuities as the masses tend to zero. We show and explain physically why their Newtonian limits do not inherit this behaviour. On the other hand, conventional ``Newtonian cosmology'', where $\Lambda$ is a constant source of the potential, displays discontinuities: e.g. for any finite range, $\Lambda$ can be totally removed.Comment: 6 pages, amplifies the ``Newtonian cosmology'' analysis. To appear as a Class. Quantum Grav. Lette