Showing papers by "Texas Christian University published in 2017"

Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies and the Distant Universe

Abstract: We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median $z\sim 0.03$). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between $z\sim 0.6$ and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July.

The Apache Point Observatory Galactic Evolution Experiment (APOGEE)

Abstract: National Science Foundation [AST-1109178, AST-1616636]; Gemini Observatory; Spanish Ministry of Economy and Competitiveness [AYA-2011-27754]; NASA [NNX12AE17G]; Hungarian Academy of Sciences; Hungarian NKFI of the Hungarian National Research, Development and Innovation Office [K-119517]; Alfred P. Sloan Foundation; National Science Foundation; U.S. Department of Energy Office of Science

The 13th Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies at Apache Point Observatory

Abstract: The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in 2014 July. It pursues three core programs: the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2), Mapping Nearby Galaxies at APO (MaNGA), and the Extended Baryon Oscillation Spectroscopic Survey (eBOSS). As well as its core program, eBOSS contains two major subprograms: the Time Domain Spectroscopic Survey (TDSS) and the SPectroscopic IDentification of ERosita Sources (SPIDERS). This paper describes the first data release from SDSS-IV, Data Release 13 (DR13). DR13 makes publicly available the first 1390 spatially resolved integral field unit observations of nearby galaxies from MaNGA. It includes new observations from eBOSS, completing the Sloan Extended QUasar, Emission-line galaxy, Luminous red galaxy Survey (SEQUELS), which also targeted variability-selected objects and X-ray-selected objects. DR13 includes new reductions of the SDSS-III BOSS data, improving the spectrophotometric calibration and redshift classification, and new reductions of the SDSS-III APOGEE-1 data, improving stellar parameters for dwarf stars and cooler stars. DR13 provides more robust and precise photometric calibrations. Value-added target catalogs relevant for eBOSS, TDSS, and SPIDERS and an updated red-clump catalog for APOGEE are also available. This paper describes the location and format of the data and provides references to important technical papers. The SDSS web site, http://www.sdss.org, provides links to the data, tutorials, examples of data access, and extensive documentation of the reduction and analysis procedures. DR13 is the first of a scheduled set that will contain new data and analyses from the planned ∼6 yr operations of SDSS-IV.

Persistence images: a stable vector representation of persistent homology

Abstract: Many data sets can be viewed as a noisy sampling of an underlying space, and tools from topological data analysis can characterize this structure for the purpose of knowledge discovery. One such tool is persistent homology, which provides a multiscale description of the homological features within a data set. A useful representation of this homological information is a persistence diagram (PD). Efforts have been made to map PDs into spaces with additional structure valuable to machine learning tasks. We convert a PD to a finite-dimensional vector representation which we call a persistence image (PI), and prove the stability of this transformation with respect to small perturbations in the inputs. The discriminatory power of PIs is compared against existing methods, showing significant performance gains. We explore the use of PIs with vector-based machine learning tools, such as linear sparse support vector machines, which identify features containing discriminating topological information. Finally, high accuracy inference of parameter values from the dynamic output of a discrete dynamical system (the linked twist map) and a partial differential equation (the anisotropic Kuramoto-Sivashinsky equation) provide a novel application of the discriminatory power of PIs.

Why is Family Firms’ Internationalization Unique? A Meta–Analysis:

Abstract: Despite its importance, there is no clear understanding of the uniqueness of family firms' internationalization. This article sheds new light on this issue with a meta-analysis of 76 studies covering 41 countries. We show that the considerable study and cross-country differences in the relationship between family firm and internationalization are explained by the roles of family control, internationalization types, and home countries' institutional contexts (i.e., minority shareholders protection and generalized trust of people from other countries). Therefore, we examine the existing divergent results using theories that reconcile some of these mixed findings and shed light on family firms' specific internationalization challenges.

Chemical tagging with APOGEE: Discovery of a large population of N-rich stars in the inner Galaxy

Abstract: Alfred P. Sloan Foundation; National Science Foundation; US Department of Energy Office of Science; University of Arizona; Brazilian Participation Group; Brookhaven National Laboratory; University of Cambridge; Carnegie Mellon University; University of Florida; French Participation Group; German Participation Group; Harvard University; Instituto de Astrofisica de Canarias; Michigan State/Notre Dame/JINA Participation Group; Johns Hopkins University; Lawrence Berkeley National Laboratory; Max Planck Institute for Astrophysics; New Mexico State University; New York University; Ohio State University; Pennsylvania State University; University of Portsmouth; Princeton University; Spanish Participation Group; University of Tokyo; University of Utah; Vanderbilt University; University of Virginia; University of Washington; Yale University; Physics Frontier Center/Joint Institute or Nuclear Astrophysics (JINA) [PHY 14-30152]; Physics Frontier Center/JINA Center for the Evolution of the Elements (JINA-CEE) by the US National Science Foundation; US National Science Foundation; Spanish Ministry of Economy and Competitiveness [AYA2010-16717, AYA2013-42781P]; Spanish Ministry of Economy and Competitiveness (MINECO) [AYA2014-56359-P]; Australian Research Council through DECRA Fellowship [DE140100598]; Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences; Ramon y Cajal fellowship [RYC-2013-14182]; MINECO [AYA-2014-58082-P]

The age–metallicity structure of the Milky Way disc using APOGEE

Abstract: The measurement of the structure of stellar populations in the Milky Way disc places fundamental constraints on models of galaxy formation and evolution. Previously, the disc’s structure has been studied in terms of populations defined geometrically and/or chemically, but a decomposition based on stellar ages provides a more direct connection to the history of the disc, and stronger constraint on theory. Here, we use positions, abundances and ages for 31 244 red giant branch stars from the Sloan Digital Sky Survey (SDSS)-APOGEE survey, spanning 3 < Rgc < 15 kpc, to dissect the disc into mono-age and mono-[Fe/H] populations at low and high [α/Fe]. For each population, with age < 2 Gyr and [Fe/H] < 0.1 dex, we measure the structure and surface-mass density contribution. We find that low [α/Fe] mono-age populations are fit well by a broken exponential, which increases to a peak radius and decreases thereafter. We show that this profile becomes broader with age, interpreted here as a new signal of disc heating and radial migration. High [α/Fe] populations are well fit as single exponentials within the radial range considered, with an average scalelength of 1.9 ± 0.1 kpc. We find that the relative contribution of high to low [α/Fe] populations at R0 is f� = 18 per cent ± 5 per cent; high [α/Fe] contributes most of the mass at old ages, and low [α/Fe] at young ages. The low and high [α/Fe] populations overlap in age at intermediate [Fe/H], although both contribute mass at R0 across the full range of [Fe/H]. The mass-weighted scaleheight hZ distribution is a smoothly declining exponential function. High [α/Fe] populations are thicker than low [α/Fe], and the average hZ increases steadily with age, between 200 and 600 pc.

A Positive Vestibular/Ocular Motor Screening (VOMS) Is Associated With Increased Recovery Time After Sports-Related Concussion in Youth and Adolescent Athletes:

Abstract: Background Vestibular and ocular motor impairments are routinely reported in patients with sports-related concussion (SRC) and may result in delayed return to play (RTP) The Vestibular/Ocular Motor Screening (VOMS) assessment has been shown to be consistent and sensitive in identifying concussion when used as part of a comprehensive examination To what extent these impairments or symptoms are associated with length of recovery is unknown Purpose To examine whether symptom provocation or clinical abnormality in specific domains of the VOMS results in protracted recovery (time from SRC to commencement of RTP protocol) Study design Cohort study (prognosis); Level of evidence, 2 Methods A retrospective chart review was conducted of 167 patients (69 girls, 98 boys; mean ± SD age, 15 ± 2 years [range, 11-19 years]) presenting with SRC in 2014 During the initial visit, VOMS was performed in which symptom provocation or clinical abnormality (eg, unsmooth eye movements) was documented by use of a dichotomous scale (0 = not present, 1 = present) The VOMS used in this clinic consisted of smooth pursuits (SMO_PUR), horizontal and vertical saccades (HOR_SAC and VER_SAC), horizontal and vertical vestibular ocular reflex (HOR_VOR and VER_VOR), near point of convergence (NPC), and accommodation (ACCOM) Domains were also categorized into ocular motor (SMO_PUR, HOR_SAC, VER_SAC, NPC, ACCOM) and vestibular (HOR_VOR, VER_VOR) Cox proportional hazard models were used to explore the relationship between the domains and recovery Alpha was set at P ≤ 05 Results Symptom provocation and/or clinical abnormality in all domains except NPC ( P = 107) and ACCOM ( P = 234) delayed recovery (domain, hazard ratio [95% CI]: SMO_PUR, 065 [047-090], P = 009; HOR_SAC, 068 [050-094], P = 018; VER_SAC, 055 [040-075], P Conclusion These data suggest that symptom provocation/clinical abnormality associated with all domains except NPC and ACCOM can delay recovery after SRC in youth and adolescents Thus, the VOMS not only may augment current diagnostic tools but also may serve as a predictor of recovery time in patients with SRC The findings of this study may lead to more effective prognosis of concussion in youth and adolescents

Understanding “It Depends” in Organizational Research: A Theory-Based Taxonomy, Review, and Future Research Agenda Concerning Interactive and Quadratic Relationships

Abstract: The study of interaction effects is critical for creating, extending, and bounding theory in organizational research Integrating and extending prior work, we present a taxonomy of two-way interact

Helicopter Parenting, Autonomy Support, and College Students' Mental Health and Well-being: The Moderating Role of Sex and Ethnicity

Abstract: Whereas parental involvement is consistently linked with positive child outcomes throughout development, parental involvement that is not developmentally appropriate and intrusive—a style of parenting called helicopter parenting—can be problematic for their child’s adjustment and well-being. Helicopter parenting can be particularly harmful during emerging adulthood when young adults are working toward developmental goals of self-reliance and autonomy. The purpose of this study was to examine sex differences in the relation between helicopter parenting and autonomy support on college students’ mental health and well-being. A secondary aim was to explore the extent to which there were ethnic differences (non-Hispanic White vs. Hispanic) in associations between parenting and college students’ outcomes. We examined several domains of mental health, including dysphoria symptoms, social anxiety, and general well-being. A sample of 118 undergraduate students (Mage = 19.82 years, SD = 1.38; 83.1 % female; 57 % European American) completed measures of parenting and mental health and well-being. The results showed that higher levels of helicopter parenting predicted lower levels of well-being for females, whereas higher levels of autonomy support predicted lower levels of dysphoria symptoms and social anxiety among males. No ethnic differences were found. The findings highlight that parents’ behavior continues to predict their child’s well-being even in emerging adulthood, and that parenting may differentially predict male and female college students’ mental health outcomes.

Effects of Road Density and Pattern on the Conservation of Species and Biodiversity

Abstract: The development and presence of roads can reduce landscape permeability, lead to habitat loss, and increase habitat fragmentation. It is these fundamental changes in landscape structure that can have both direct and indirect impacts on the conservation of species and biodiversity. In this review, I examine 215 research studies conducted between 2011 and 2015 that explore the impacts of roads and road networks on a wide range of species. I divided these studies into four main categories: 1) the direct effects of roads on wildlife, 2) the indirect effects of roads on wildlife, 3) the consequences of road networks on wildlife populations, and 4) survey design and mitigation including both innovations and evaluations. I found that the majority of studies (38%) explored the indirect effects of roads on wildlife, including displacement, fitness consequences, and road crossing ability of wildlife. Nevertheless, despite there being a pressing need to understand how existing road networks impact wildlife and how increasing road density may influence local and regional population persistence, only 10% of the studies considered the implications of road networks on wildlife. However, there is an increasing trend towards the development of predictive models that can be used for a better understanding of road network impacts, assess landscape connectivity, and devise mitigation. This review also highlighted the continued need to devise and evaluate mitigation measures so transportation authorities and conservation practitioners may be better equipped to address the ecological implications of roads and proposed road development.

Efficacy of a randomized trial examining commercial weight loss programs and exercise on metabolic syndrome in overweight and obese women.

Abstract: While commercial dietary weight-loss programs typically advise exercise, few provide actual programing. The goal of this study was to compare the Curves Complete 90-day Challenge (CC, n = 29), which incorporates exercising and diet, to programs advocating exercise (Weight Watchers Points Plus (WW, n = 29), Jenny Craig At Home (JC, n = 27), and Nutrisystem Advance Select (NS, n = 28)) or control (n = 20) on metabolic syndrome (MetS) and weight loss. We randomized 133 sedentary, overweight women (age, 47 ± 11 years; body mass, 86 ± 14 kg; body mass index, 35 ± 6 kg/m2) into respective treatment groups for 12 weeks. Data were analyzed using chi square and general linear models adjusted for age and respective baseline measures. Data are means ± SD or mean change ± 95% confidence intervals (CIs). We observed a significant trend for a reduction in energy intake for all treatment groups and significant weight loss for all groups except control: CC (−4.32 kg; 95% CI, −5.75, −2.88), WW (−4.31 kg; 95% CI, −5.82, −2...

APOGEE Chemical Abundances of the Sagittarius Dwarf Galaxy

Abstract: The Apache Point Observatory Galactic Evolution Experiment (APOGEE) provides the opportunity to measure elemental abundances for C, N, O, Na, Mg, Al, Si, P, K, Ca, V, Cr, Mn, Fe, Co, and Ni in vast numbers of stars. We analyze the chemical abundance patterns of these elements for 158 red giant stars belonging to the Sagittarius dwarf galaxy (Sgr). This is the largest sample of Sgr stars with detailed chemical abundances and the first time C, N, P, K, V, Cr, Co, and Ni have been studied at high-resolution in this galaxy. We find that the Sgr stars with [Fe/H] $\gtrsim$ -0.8 are deficient in all elemental abundance ratios (expressed as [X/Fe]) relative to the Milky Way, suggesting that Sgr stars observed today were formed from gas that was less enriched by Type II SNe than stars formed in the Milky Way. By examining the relative deficiencies of the hydrostatic (O, Na, Mg, and Al) and explosive (Si, P, K, and Mn) elements, our analysis supports the argument that previous generations of Sgr stars were formed with a top-light IMF, one lacking the most massive stars that would normally pollute the ISM with the hydrostatic elements. We use a simple chemical evolution model, flexCE to further backup our claim and conclude that recent stellar generations of Fornax and the LMC could also have formed according to a top-light IMF.

APOGEE chemical abundances of globular cluster giants in the inner Galaxy

Abstract: We report chemical abundances obtained by Sloan Digital Sky Survey (SDSS)-III/Apache Point Observatory Galactic Evolution Experiment for giant stars in five globular clusters located within 2.2 kpc of the Galactic Centre. We detect the presence of multiple stellar populations in four of those clusters (NGC 6553, NGC 6528, Terzan 5 and Palomar 6) and find strong evidence for their presence in NGC 6522. All clusters with a large enough sample present a significant spread in the abundances of N, C, Na and Al, with the usual correlations and anticorrelations between various abundances seen in other globular clusters. Our results provide important quantitative constraints on theoretical models for self-enrichment of globular clusters, by testing their predictions for the dependence of yields of elements such as Na, N, C and Al on metallicity. They also confirm that, under the assumption that field N-rich stars originate from globular cluster destruction, they can be used as tracers of their parental systems in the high-metallicity regime.

Leading to Stimulate Employees' Ideas: A Quantitative Review of Leader–Member Exchange, Employee Voice, Creativity, and Innovative Behavior

Abstract: Through social exchange, leaders can offer relational support or resources to facilitate employees' proactive attempts to bring positive change (voice) or novel ideas (creativity) and behaviors (innovative behavior) to their work. We consider these three outcomes under the same nomological network as they all represent employees' idea contribution to the organisation. The present paper thus meta-analytically reviews the findings of research relating leader–member exchange (LMX) to voice (37 samples), creativity (53 samples), and innovative behavior (29 samples). Results show that LMX positively predicts voice, creativity, and innovative behavior. Moreover, LMX is more strongly related with creativity than with voice or innovative behavior, a significant difference maintained even after controlling for study characteristics that may act as confounding variables. Implications of our findings and directions for future research are also discussed.

Adding the s-Process Element Cerium to the APOGEE Survey : Identification and Characterization of Ce II Lines in the H-band Spectral Window

Abstract: National Science Foundation [AST1109888]; Ramon y Cajal fellowship [RYC201314182]; Spanish Ministry of Economy and Competitiveness (MINECO) [AYA201458082-P]; Premium Postdoctoral Research Program of the Hungarian Academy of Sciences; Hungarian NKFI Grants of the Hungarian National Research, Development and Innovation Office [K-119517]; National Aeronautics and Space Administration; National Science Foundation; Spanish MINECO [AYA2014-56359-P]; Birgit and Hellmuth Hertz' Foundation; Royal Physiographic Society of Lund, Sweden; Alfred P. Sloan Foundation; U.S. Department of Energy Office of Science; High-Performance Computing at the University of Utah

A Service Perspective for Human Capital Resources: A Critical Base for Strategy Implementation

Abstract: Although strategy formulation has received the lion’s share of attention in strategic management research, strategy implementation is widely considered to provide the greatest challenges for top ex...

Examining the contributions of syntactic awareness and syntactic knowledge to reading comprehension

Abstract: Purpose The purpose of this study was to examine the effect(s) of syntactic knowledge and syntactic awareness on adolescents' reading comprehension. Method One hundred and seventy-nine, 9th and 10th grade students' syntactic awareness, syntactic knowledge and reading comprehension skills were assessed. In addition, other known contributors to reading comprehension were assessed including word level reading, short-term memory and vocabulary knowledge skills. Results Path analysis was used to analyse the direct and indirect effects of syntactic awareness and syntactic knowledge on reading comprehension. Students' syntactic knowledge directly accounted for significant variance in reading comprehension. Syntactic awareness indirectly accounted for significant variance in reading comprehension through syntactic knowledge. Conclusions This study confirmed the significant effects of syntactic knowledge and syntactic awareness on reading comprehension among adolescent students. This is one of the very few studies to examine both knowledge and awareness of syntax simultaneously and to determine that syntactic knowledge mediates the contribution of syntactic awareness to adolescent students' reading comprehension.