5,771 research outputs found

    Student Veterans/Service Members' Engagement in College and University Life and Education

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    Since the passage of the Post-9/11 Veterans Educational Assistance Act of 2008, also known as the Post-9/11 GI Bill, the enrollment of active-duty service members and veterans in American colleges and universities has increased substantially. According to the Department of Veterans Affairs, more than three-quarters of a million veterans have used their earned benefit to enroll in postsecondary courses. In response to the influx of veteran student enrollment, a group of higher education associations and veterans' organizations collaborated in 2009 and 2012 on a study that asked college and university administrators whether their institutions had geared up campus programs and services specifically designed to support the unique needs of veterans.1 The results indicated that administrators had indeed increased support levels, sometimes by quite significant margins.But how do student veterans/service members perceive their experiences at higher education institutions? To date, there is little or no information to assess whether the efforts by institutions to provide targeted programs and services are helpful to the veterans and service members enrolled in colleges and universities. Similarly, not much is known about the transition to postsecondary education from military service experienced by student veterans/service members, or whether these students are engaged in both academic programs and college and university life to their fullest potential. In this context, this issue brief explores student veteran/service member engagement in postsecondary education. The brief utilizes data from the 2012 National Survey of Student Engagement (NSSE), an annual survey of students enrolled in four-year universities, to assess how student veterans/service members perceive their integration on campus.A key finding is that student veterans/servicemembers are selective about the campus life and academic activities in which they invest their time. Student veterans/service members are morelikely to be first-generation students -- the first in their families to attend a college or university -- and older than nonveteran/civilian students; they therefore tend to have responsibilities outside of higher education that put constraints on their time.Student veterans/service members report placing greater emphasis on academic areas that they find essential for academic progress than on college and university life and activities -- academic or otherwise -- that are not essential for success in the courses in which they are enrolled. Student veterans/ service members are less likely to participate in co curricular activities, and they dedicate less time to relaxing and socializing than nonveteran/ civilian students

    The Phase-Space Density Profiles of Cold Dark Matter Halos

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    We examine the coarse-grained phase-space density profiles of a set of recent, high-resolution simulations of galaxy-sized Cold Dark Matter (CDM) halos. Over two and a half decades in radius the phase-space density closely follows a power-law, ρ/σ3rα\rho/\sigma^3 \propto r^{-\alpha}, with α=1.875\alpha = 1.875. This behaviour matches the self-similar solution obtained by Bertschinger for secondary infall in a uniformly expanding universe. On the other hand, the density profile corresponding to Bertschinger's solution (a power-law of slope r2α6r^{2\alpha-6}) differs significantly from the density profiles of CDM halos. We show that isotropic mass distributions with power-law phase-space density profiles form a one-parameter family of structures controlled by κ\kappa, the ratio of the velocity dispersion to the peak circular velocity. For κ=α=1.875\kappa=\alpha=1.875 one recovers the power-law solution ρr2α6\rho \propto r^{2\alpha-6}. For κ\kappa larger than some critical value, κcr\kappa_{cr}, solutions become non-physical, leading to negative densities near the center. The critical solution, κ=κcr\kappa =\kappa_{cr}, has the narrowest phase-space density distribution compatible with the power-law phase-space density stratification constraint. Over three decades in radius the critical solution is indistinguishable from an NFW profile. Our results thus suggest that the NFW profile is the result of a hierarchical assembly process that preserves the phase-space stratification of Bertschinger's infall model but which ``mixes'' the system maximally, perhaps as a result of repeated merging.Comment: 16 pages, 4 figures; submitted to The Astrophysical Journa

    Tobacco Research and Development

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    A book chapter on Zimbabwe tobacco research and its development.Zimbabwe became the third largest exporter of high quality tobacco in the world, although the tobacco industry originated from modest beginnings. The production of tobacco was started by the indigenous population before the arrival of white settlers. Later, a small group of white farmers planted it as a potentially profitable venture before the end of the nineteenth century. In 1905,100 farmers were growing the crop and by 1910 about 90,000kgs of flue-cured tobacco were being exported annually to Britain (Haviland, 1952). Sustainable production of any product hinges on its research and development. In the many changes of fortune that occurred during the ensuing years it became obvious that the internationally orientated export industry required specialized and up-to-date research support to solve the problems that were increasingly besetting growers

    Motivation to do well on low-stakes tests

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    The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Title from title screen of research.pdf file (viewed on September 20, 2007)Vita.Thesis (Ph. D.) University of Missouri-Columbia 2007.According to the self-determination theory, students provided with choice, a rationale, and acknowledgement should report higher levels of motivation and test performance on a low-stakes exam compared to other students. However, there is also some evidence that financial, performance-contingent incentives may facilitate students' test-taking motivation and performance. This experimental study investigated differences in test-taking motivation and test score on a math achievement test due to three interventions: autonomy-support, lottery, or control. The autonomy support group received instructions that included a meaningful rationale, acknowledgment that the task might not be interesting, and avoidance of controlling language. The lottery group received 0, 1, or 2 chances in the lottery, depending on their test scores. For the autonomy and control groups, test taking effort had a significant impact on test performance. However, students who received autonomy support reported higher levels of test effort, but scored significantly lower than students in the lottery group. The performance-based lottery system improved test scores, but only for male test-takers. Based on the results it appears that the two interventions activate different relationships of key variables during a testing situation. The lottery intervention significantly favored males during the math exam. On the other hand, the autonomy intervention minimized gender differences, and facilitated the role of interest and effort during the exam.Includes bibliographical reference

    The Velocity Function of Galaxies

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    We present a galaxy circular velocity function, Psi(log v), derived from existing luminosity functions and luminosity-velocity relations. Such a velocity function is desirable for several reasons. First, it enables an objective comparison of luminosity functions obtained in different bands and for different galaxy morphologies, with a statistical correction for dust extinction. In addition, the velocity function simplifies comparison of observations with predictions from high-resolution cosmological N-body simulations. We derive velocity functions from five different data sets and find rough agreement among them, but about a factor of 2 variation in amplitude. These velocity functions are then compared with N-body simulations of a LCDM model (corrected for baryonic infall) in order to demonstrate both the utility and current limitations of this approach. The number density of dark matter halos and the slope of the velocity function near v_*, the circular velocity corresponding to an ~L_* spiral galaxy, are found to be comparable to that of observed galaxies. The primary sources of uncertainty in construction of Psi(log v) from observations and N-body simulations are discussed and explanations are suggected to account for these discrepancies.Comment: Latex. 28 pages, 4 figures. Accepted by Ap

    Morphology of the Acromion and Scapular Spine with Special Interest in the Strength & Failure Prediction after Reverse Total Shoulder Replacement

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    Scapular spine fractures following a reverse arthroplasty are a significant clinical concern. This ongoing study looks at the morphology of the acromion and scapular spine with an interest in the strength and failure prediction of the bone. Digital 3D models of the scapular spine were created from cadaver CTs, then bone density and distribution data was obtained. It was found that the cortical bone was most dense just medial of the lateral angle. The cross-sectional area here was also the largest and decreased medially. This has important implications for implant fixation hardware as cortical bone --compared to cancellous bone-- is stronger, denser, and therefore a better option for fixation hardware

    Dark Matter and Stellar Mass in the Luminous Regions of Disk Galaxies

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    We investigate the correlations among stellar mass (M_*), disk scale length (R_d), and rotation velocity at 2.2 disk scale lengths (V_2.2) for a sample of 81 disk-dominated galaxies (disk/total >= 0.9) selected from the SDSS. We measure V_2.2 from long-slit H-alpha rotation curves and infer M_* from galaxy i-band luminosities (L_i) and g-r colors. We find logarithmic slopes of 2.60+/-0.13 and 3.05+/-0.12 for the L_i-V_2.2 and M_*-V_2.2 relations, somewhat shallower than most previous studies, with intrinsic scatter of 0.13 dex and 0.16 dex. Our direct estimates of the total-to-stellar mass ratio within 2.2R_d, assuming a Kroupa IMF, yield a median ratio of 2.4 for M_*>10^10 Msun and 4.4 for M_*=10^9-10^10 Msun, with large scatter at a given M_* and R_d. The typical ratio of the rotation speed predicted for the stellar disk alone to the observed rotation speed at 2.2R_d is ~0.65. The distribution of R_d at fixed M_* is broad, but we find no correlation between disk size and the residual from the M_*-V_2.2 relation, implying that this relation is an approximately edge-on view of the disk galaxy fundamental plane. Independent of the assumed IMF, this result implies that stellar disks do not, on average, dominate the mass within 2.2R_d. We discuss our results in the context of infall models of disk formation in cold dark matter halos. A model with a disk-to-halo mass ratio m_d=0.05 provides a reasonable match to the R_d-M_* distribution for spin parameters \lambda ranging from ~0.04-0.08, and it yields a reasonable match to the mean M_*-V_2.2 relation. A model with m_d=0.1 predicts overly strong correlations between disk size and M_*-V_2.2 residual. Explaining the wide range of halo-to-disk mass ratios within 2.2R_d requires significant scatter in m_d values, with systematically lower m_d for galaxies with lower MM_*.Comment: 18 pages, 2 tables, 7 figures, Accepted to ApJ, Table 1 updated, otherwise minor change

    Halo Substructure and the Power Spectrum

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    In this proceeding, we present the results of a semi-analytic study of CDM substructure as a function of the primordial power spectrum. We apply our method to several tilted models in the LCDM framework with n=0.85-1.1, sigma_8=0.65-1.2 when COBE normalized. We also study a more extreme, warm dark matter-like spectrum that is sharply truncated below a scale of 10^10 h^-1 Msun. We show that the mass fraction of halo substructure is not a strong function of spectral slope, so it likely will be difficult to constrain tilt using flux ratios of gravitationally lensed quasars. On the positive side, all of our CDM-type models yield projected mass fractions in good agreement with strong lensing estimates: f \sim 1.5% at M \sim 10^8 Msun. The truncated model produces a significantly smaller fraction, f \lsim 0.3%, suggesting that warm dark matter-like spectra may be distinguished from CDM spectra using lensing. We also discuss the issue of dwarf satellite abundances, with emphasis on the cosmological dependence of the map between the observed central velocity dispersion of Milky Way satellites and the maximum circular velocities of their host halos. In agreement with earlier work, we find that standard LCDM over-predicts the estimated count of Milky Way satellites at fixed Vmax by an order of magnitude, but tilted models do better because subhalos are less concentrated. Interestingly, under the assumption that dwarfs have isotropic velocity dispersion tensors, models with significantly tilted spectra (n \lsim 0.85, sigma_8 \lsim 0.7) may under-predict the number of large Milky Way satellites with Vmax \gsim 40 km/s.Comment: 5 pages, 2 figures. Poster contribution to the 13th Annual Astrophysics Conference in Maryland, The Emergence of Cosmic Structur
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