The Stellar Haloes of Massive Elliptical Galaxies III: Kinematics at Large Radius

We present a 2D kinematic analysis out to ~2-5 effective radii (Re) of 33 massive elliptical galaxies with stellar velocity dispersions larger than 150 km/s. Our observations were taken using the Mitchell Spectrograph (formerly VIRUS-P), a spectrograph with a large 107 x 107 square arcsecond field-of-view that allows us to construct robust, spatially resolved kinematic maps of the mean velocity and velocity dispersion for each galaxy extending to at least 2 Re. Using these maps we study the radial dependence of the stellar angular momentum and other kinematic properties. We see the familiar division between slow and fast rotators persisting out to large radius in our sample. Centrally slow rotating galaxies, which are almost universally characterised by some form of kinematic decoupling or misalignment, remain slowly rotating in their halos. The majority of fast rotating galaxies show either increases in specific angular momentum outwards or no change beyond $R_e$. The generally triaxial nature of the slow rotators suggests that they formed through mergers, consistent with a "two-phase" picture of elliptical galaxy formation. However, we do not observe the sharp transitions in kinematics proposed in the literature as a signpost of moving from central dissipationally-formed components to outer accretion-dominated haloes.Comment: 19 pages, 13 figures. 17 Appendix pages, 19 Appendix figure

The Rising Stellar Velocity Dispersion of M87 from Integrated Starlight

We have measured the line-of-sight velocity distribution from integrated stellar light at two points in the outer halo of M87 (NGC 4486), the second-rank galaxy in the Virgo Cluster. The data were taken at R = 480" ($\sim 41.5$ kpc) and R = 526" ($\sim 45.5$ kpc) along the SE major axis. The second moment for a non-parametric estimate of the full velocity distribution is $420 \pm 23$ km/s and $577 \pm 35$ km/s respectively. There is intriguing evidence in the velocity profiles for two kinematically distinct stellar components at the position of our pointing. Under this assumption we employ a two-Gaussian decomposition and find the primary Gaussian having rest velocities equal to M87 (consistent with zero rotation) and second moments of $383 \pm 32$ km/s and $446 \pm 43$ km/s respectively. The asymmetry seen in the velocity profiles suggests that the stellar halo of M87 is not in a relaxed state and confuses a clean dynamical interpretation. That said, either measurement (full or two component model) shows a rising velocity dispersion at large radii, consistent with previous integrated light measurements, yet significantly higher than globular cluster measurements at comparable radial positions. These integrated light measurements at large radii, and the stark contrast they make to the measurements of other kinematic tracers, highlight the rich kinematic complexity of environments like the center of the Virgo Cluster and the need for caution when interpreting kinematic measurements from various dynamical tracers.Comment: 16 pages, 5 figures; accepted for publication in The Astrophysical Journa

Galaxy Kinematics With Virus-P: The Dark Matter Halo Of M87

We present two-dimensional stellar kinematics of M87 out to R = 238 '' taken with the integral field spectrograph VIRUS-P. We run a large set of axisymmetric, orbit-based dynamical models and find clear evidence for a massive dark matter halo. While a logarithmic parameterization for the dark matter halo is preferred, we do not constrain the dark matter scale radius for a Navarro-Frenk-White (NFW) profile and therefore cannot rule it out. Our best-fit logarithmic models return an enclosed dark matter fraction of 17.2(-5.0)(+5.0)% within one effective radius (R-e congruent to 100 ''), rising to 49.4(-8.8)(+7.2)% within 2 R-e. Existing SAURON data (R <= 13 ''), and globular cluster (GC) kinematic data covering 145 '' <= R <= 554 '' complete the kinematic coverage to R = 47 kpc (similar to 5R(e)). At this radial distance, the logarithmic dark halo comprises 85.3(-2.4)(+2.5)% of the total enclosed mass of 5.7(-0.9)(+1.3) x 10(12) M-circle dot making M87 one of the most massive galaxies in the local universe. Our best-fit logarithmic dynamical models return a stellar mass-to-light ratio (M/L) of 9.1(-0.2)(+0.2) (V band), a dark halo circular velocity of 800(-25)(+75) km s(-1), and a dark halo scale radius of 36(-3)(+7) kpc. The stellar M/L, assuming an NFW dark halo, is well constrained to 8.20(-0.10)(+0.05) (V band). The stars in M87 are found to be radially anisotropic out to R congruent to 0.5 R-e, then isotropic or slightly tangentially anisotropic to our last stellar data point at R = 2.4 R-e where the anisotropy of the stars and GCs are in excellent agreement. The GCs then become radially anisotropic in the last two modeling bins at R = 3.4 R-e and R = 4.8 R-e. As one of the most massive galaxies in the local universe, constraints on both the mass distribution of M87 and anisotropy of its kinematic components strongly inform our theories of early-type galaxy formation and evolution in dense environments.Astronom

The neurophysiology of intersensory selective attention and task switching

Our ability to selectively attend to certain aspects of the world and ignore others is fundamental to our day-to-day lives. The need for selective attention stems from capacity limitations inherent in our perceptual and cognitive processing architecture. Because not every elemental piece of our environment can be fully processed in parallel, the nervous system must prioritize processing. This prioritization is generally referred to as selective attention. Meanwhile, we are faced with a world that is constantly in flux, such that we have to frequently shift our attention from one piece of the environment to another and from one task to another. This process is generally referred to as task-switching. Neural oscillations in the alpha band (~8-14 Hz) have been shown to index the distribution of selective attention, and there is increasing evidence that oscillations in this band are in fact utilized by the nervous system to suppress distracting, task-irrelevant information. In order to elaborate on what is known of the function of alpha oscillations as well as current models of both intersensory selective attention and task switching, I investigated the dynamics of alpha amplitude modulations within the context of intersenory selective attention and task switching in neurologically typical young adults. Participants were alternately cued to attend to either the visual or auditory aspect of a compound audio-visual stimulus while high-density electroencephalography was recorded. It is typically found that alpha power increases over parieto-occipital cortices when attention is directed away from the visual modality and to the auditory modality. I report evidence that alpha oscillations play a role in task-switching (e.g., when switching from attending the visual task versus repeating this task), specifically as biasing signals, that may operate to re-weight competition among two tasks-sets. I further investigated the development of these same processes in school-aged children and adolescents. While exhibiting typical patterns of alpha modulations relevant to selective attention, Young school-aged children (8-12 years), compared to older participants, did not demonstrate specific task switching modulation of alpha oscillations, suggesting that this process does not fully develop until late adolescence. Finally, children and adolescents on the autism spectrum failed altogether to exhibit differentiation of alpha power between attend-visual and attend-auditory conditions--an effect present in age and IQ matched controls--suggesting that ASD individuals may have a deficit in the overall top-down deployment of alpha oscillatory biasing signals. This could result in an inability to ignore distracting information in the environment, leading to an overwhelming, disordered experience of the world, resulting in profound effects on the both social interaction and cognitive development. Altogether, these findings add to growing evidence that alpha oscillations serve as domain general biasing signals and are integral to our flexible goal-oriented behavior. Furthermore, the flexible use of these biasing signals in selective attention and task switching develops over a protracted period, and appears to be aberrant in autism spectrum disorder

Managing the matrix: decadal responses of eucalypt-dominated savanna to ambient fire regimes

Much of our understanding of the response of savanna systems to fire disturbance relies on observations derived from manipulative fire plot studies. Equivocal findings from both recent Australian and African savanna fire plot assessments have significant implications for informing conservation management and reliable estimation of biomass stocks and dynamics. Influential northern Australian replicated fire plot studies include the 24-year plot-scale Munmarlary and the five-year catchment-scale Kapalga, mesic savanna ( . 1000 mm/yr of rainfall) experiments in present-day Kakadu National Park. At Munmarlary, under low-to-moderate-intensity fire treatments, woody vegetation dominated by mature eucalypts was found to be structurally stable. At Kapalga, substantial declines in woody biomass were observed under more intense fire treatments, and modeling assessments implicate early-season fires as having adverse effects on longer-term tree recruitment. Given these contrasting perspectives, here we take advantage of a landscape-scale fire response monitoring program established on three major northern Australian conservation reserves (Kakadu, Litchfield, and Nitmiluk National Parks). Using statistical modeling we assess the decadal effects of ambient fire regime parameters (fire frequency, severity, seasonality, time since fire) on 32 vegetation structure components and abundance of 21 tree and 16 grass species from 122 monitoring plots. Over the study period the mean annual frequency of burning of plots was 0.53, comprising mostly early-dry-season, low-severity fires. Structural and species responses were variable but often substantial, notably resulting in stem recruitment and declines in juveniles, but only weakly explained by fire regime and habitat variables. Modeling of these observations under three realistic scenarios (increased fire severity under projected worsening climate change; modest and significant reductions in fire frequency to meet conservation criteria) indicates that all scenarios have positive and negative structural implications. Effecting significant regional fire regime change (e.g., reduction in frequency and size of severe fires) is demonstrably feasible, but it incurs risks and potentially some undesirable structural consequences. Given recent Australian and African experience, the generality and application of landscape-scale implications derived from manipulative fire assessments (including variable grazing and browsing regimes) in savanna require more critical assessment

Barefoot Training: Effects on EMG Activity of Gluteus Medius and Tensor Fascia Latae in Habitually Shod Runners

Purpose/Hypothesis: Running has been a common practice in humans since the species’ dawn. Due to its relative ease and low cost, running continues to be one of the most popular forms of exercise today. Although running provides many benefits such as disease prevention, injury prevalence in running is high. The trend of minimalist shoes and barefoot training has gained popularity over the decade as a return to a more natural form of running. Some researcher hypothesize that barefoot running can reduce injury rate by changing the biomechanics of the runner. In this study we propose a different hypothesis: barefoot running changes activity of musculature of the hip, increasing activation in muscles that are commonly weak in injured runners. Research investigating the hip muscle activity and movement with barefoot running is lacking in literature; thus, giving rise to the purpose of this study. This multifactorial study was performed to explore the effect of barefoot training on the muscular activity of the gluteus medius (GM) and tensor fascia latae (TFL). The hypothesis being tested was that barefoot training period would increase the muscle activity of GM and decrease the muscle activity of TFL. Materials/Methods: Twenty-two subjects, 14 females and 8 males, with a mean age of 22.8 completed the pre-testing electromyography (EMG) analyses. EMG muscle activity of TFL and GM was recorded during a maximal isometric contraction, a barefoot running and walking trial and a shod running and walking trial. Subjects were randomly assigned to a barefoot running group (N=13) and shod running group (N=9). Participants completed a 6-week training program consisting of running twice a week. The first week of training consisted of 10 minutes of running (either barefoot or shod) with a 2- minute increase each week, reaching a maximum running period of 20 minutes during the final week. Following the training program, post-test EMG was performed and analyzed. Results: No significant differences in change of EMG activity of the GM and TFL was found between the barefoot and shod training groups from pre-testing to post-testing data collection. Conclusions: Due to no statistically significant differences in change of EMG activity of the GM and TFL between the training groups from pre- to post-test trials, further research is recommended to explore the impact of a barefoot training protocol on GM and TFL muscle activity. Clinical Relevance: This study provides insight to the muscle activity occurring at the hip when foot attire is altered during training. No statistically significant change was found between barefoot or shod training groups in regard to change in muscle activity from pre-test to post-test. This lack of statistical significance may have been due to lack of statistical power, as the number of subjects was low. The training period also may have not provided enough volume to create a stimulus to significantly change muscle activity. While there were no statistically significant findings, trends in the data pointed towards a greater change in GM activity for the barefoot group from pre-test to post-test. Replicating the study with a higher number of subjects or a larger training volume may yield significant results in future research. In addition, collecting other data such as V02 max, running economy or foot strike pattern also may reveal other physiological changes that can occur with barefoot training

ATK Launch Vehicle (ALV-X1) Liftoff Acoustic Environments: Prediction vs. Measurement

The ATK Launch Vehicle (ALV-X1) provided an opportunity to measure liftoff acoustic noise data. NASA Marshall Space Flight Center (MSFC) engineers were interested in the ALV-X1 launch because the First Stage motor and launch pad conditions, including a relativity short deflector ducting, provide a potential analogue to future Ares I launches. This paper presents the measured liftoff acoustics on the vehicle and tower. Those measured results are compared to predictions based upon the method described in NASA SP-8072 "Acoustic Loads Generated by the Propulsion System" and the Vehicle Acoustic Environment Prediction Program (VAEPP) which was developed by MSFC acoustics engineers. One-third octave band sound pressure levels will be presented. This data is useful for the ALV-X1 in validating the pre-launch environments and loads predictions. Additionally, the ALV-X1 liftoff data can be scaled to define liftoff environments for the NASA Constellation program Ares vehicles. Vehicle liftoff noise is caused by the supersonic jet flow interaction with surrounding atmosphere or more simply, jet noise. As the vehicle's First Stage motor is ignited, an acoustic noise field is generated by the exhaust. This noise field persists due to the supersonic jet noise and reflections from the launch pad and tower, then changes as the vehicle begins to liftoff from the launch pad. Depending on launch pad and adjacent tower configurations, the liftoff noise is generally very high near the nozzle exit and decreases rapidly away from the nozzle. The liftoff acoustic time range of interest is typically 0 to 20 seconds after ignition. The exhaust plume thermo-fluid mechanics generates sound at approx.10 Hz to 20 kHz. Liftoff acoustic noise is usually the most severe dynamic environment for a launch vehicle or payload in the mid to high frequency range (approx.50 to 2000 Hz). This noise environment can induce high-level vibrations along the external surfaces of the vehicle and surrounding launch facility structures. The acoustic pressure fluctuations will induce severe vibrations in relatively large lightweight structures. Consequently, there is the potential for failure of the structure or attached electrical components. Due to these potential failures, the liftoff acoustic noise is one of the noise source inputs used to determine the vibro-acoustic qualification environment for a launch vehicle and its components

The Effects of Completing PREP Academy: A University-Based Transition Project for Students with Disabilities (Practice Brief)

This practice brief provides an overview of a project designed to support students with disabilities considering postsecondary education. Postsecondary Rewarding Education is Possible (PREP) Academy was developed by individuals from a state vocational rehabilitation agency and a public research university. PREP Academy is a campus-based, weeklong experience in which students participate in activities designed to mirror the “college experience.” In an evaluation of the project’s second year, a total of 23 students and six parents/guardians completed a pre- and post-survey to examine how attending the project affected students’ perceptions related to students attending college. Interview data from three student and parent/guardian pairs were collected to further explore students’ perceptions and to learn what components of the project were most beneficial. Results provided evidence both students and parents/guardians believe students are better prepared to attend college after participating. An emerging theme related to increasing the project’s emphasis on mirroring aspects of college was identified

The MASSIVE Survey II: Stellar Population Trends Out to Large Radius in Massive Early Type Galaxies

We examine stellar population gradients in ~100 massive early type galaxies spanning 180 < sigma* < 370 km/s and M_K of -22.5 to -26.5 mag, observed as part of the MASSIVE survey (Ma et al. 2014). Using integral-field spectroscopy from the Mitchell Spectrograph on the 2.7m telescope at McDonald Observatory, we create stacked spectra as a function of radius for galaxies binned by their stellar velocity dispersion, stellar mass, and group richness. With excellent sampling at the highest stellar mass, we examine radial trends in stellar population properties extending to beyond twice the effective radius (~2.5 R_e). Specifically, we examine trends in age, metallicity, and abundance ratios of Mg, C, N, and Ca, and discuss the implications for star formation histories and elemental yields. At a fixed physical radius of 3-6 kpc (the likely size of the galaxy cores formed at high redshift) stellar age and [alpha/Fe] increase with increasing sigma* and depend only weakly on stellar mass, as we might expect if denser galaxies form their central cores earlier and faster. If we instead focus on 1-1.5 R_e, the trends in abundance and abundance ratio are washed out, as might be expected if the stars at large radius were accreted by smaller galaxies. Finally, we show that when controlling for \sigmastar, there are only very subtle differences in stellar population properties or gradients as a function of group richness; even at large radius internal properties matter more than environment in determining star formation history.Comment: 17 pages, 9 figures, accepted by ApJ; resubmitted with updated reference