Güneş IŞIKSEL et Emmanuel SZUREK [dir.], Turcs et Français. Une histoire culturelle, 1860-1960

Issu d’un colloque international qui s’est tenu en mars 2010 à l’École normale supérieure, ce volume préfacé par François Georgeon recueille les contributions d’historiens sur les relations entre Français et Turcs sur un siècle (1860-1960), mettant l’accent davantage sur le XXe que sur le XIXe siècle. L’ouvrage s’ancre dans une historiographie culturelle de la Turquie déjà riche dans les domaines de l’histoire du livre et de la presse, de l’enseignement et des missions, des sciences et des te..

The Effect of the 6-Minute Walk Test on Vertical Leap

The vertical jump test is a test often used to assess lower body power (Haff and Triplett, 2016). The six-minute walk test (6MWT) has been useful in assessing for a variety of respiratory or cardiac diseases (Olsson, 2005). The 6MWT requires participants to walk as far as they can in the six minutes, which is physically taxing on the body (Olsson, 2005). Studies have found that a gradual, progressive warmup can improve performance whereas static stretching can negatively impact performance (Vetter, 2007). The purpose of this study was to assess the effects of a 6MWT, and a 6-minute treadmill walk test on vertical jump. It was hypothesized that the six-minute treadmill test would produce a higher vertical jump than the 6MWT because of the oxidative work the 6MWT requires.https://digitalcommons.gardner-webb.edu/exercise-science-research-proposal-posters/1150/thumbnail.jp

Güneş IŞIKSEL et Emmanuel SZUREK [dir.], Turcs et Français. Une histoire culturelle, 1860-1960

Issu d’un colloque international qui s’est tenu en mars 2010 à l’École normale supérieure, ce volume préfacé par François Georgeon recueille les contributions d’historiens sur les relations entre Français et Turcs sur un siècle (1860-1960), mettant l’accent davantage sur le XXe que sur le XIXe siècle. L’ouvrage s’ancre dans une historiographie culturelle de la Turquie déjà riche dans les domaines de l’histoire du livre et de la presse, de l’enseignement et des missions, des sciences et des te..

Weather on Other Worlds. II. Survey Results: Spots Are Ubiquitous on L and T Dwarfs

We present results from the "Weather on Other Worlds" Spitzer Exploration Science program to investigate photometric variability in L and T dwarfs, usually attributed to patchy clouds. We surveyed 44 L3-T8 dwarfs, spanning a range of $J-K_s$ colors and surface gravities. We find that 14/23 (61%; 95% confidence interval: 41%-78%) of our single L3-L9.5 dwarfs are variable with peak-to-peak amplitudes between 0.2% and 1.5%, and 5/16 (31%; 95% confidence interval: 14%-56%) of our single T0-T8 dwarfs are variable with amplitudes between 0.8% and 4.6%. After correcting for sensitivity, we find that 80% (95% confidence interval: 53%-100%) of L dwarfs vary by >0.2%, and 36% (95% confidence interval: 19%-52%) of T dwarfs vary by >0.4%. Given viewing geometry considerations, we conclude that photospheric heterogeneities causing >0.2% 3-5-micron flux variations are present on virtually all L dwarfs, and probably on most T dwarfs. A third of L dwarf variables show irregular light curves, indicating that L dwarfs may have multiple spots that evolve over a single rotation. Also, approximately a third of the periodicities are on time scales >10 h, suggesting that slowly-rotating brown dwarfs may be common. We observe an increase in the maximum amplitudes over the entire spectral type range, revealing a potential for greater temperature contrasts in T dwarfs than in L dwarfs. We find a tentative association (92% confidence) between low surface gravity and high-amplitude variability among L3-L5.5 dwarfs. Although we can not confirm whether lower gravity is also correlated with a higher incidence of variables, the result is promising for the characterization of directly imaged young extrasolar planets through variability.Comment: 42 pages, 11 figures, 2 tables, accepted by Ap

Vertical Atmospheric Structure in a Variable Brown Dwarf: Pressure-dependent Phase Shifts in Simultaneous Hubble Space Telescope-Spitzer Light Curves

Heterogeneous clouds or temperature perturbations in rotating brown dwarfs produce variability in the observed flux. We report time-resolved simultaneous observations of the variable T6.5 brown dwarf 2MASSJ22282889-431026 over the wavelength ranges 1.1-1.7 microns and broadband 4.5 microns. Spectroscopic observations were taken with Wide Field Camera 3 on board the Hubble Space Telescope and photometry with the Spitzer Space Telescope. The object shows sinusoidal infrared variability with a period of 1.4 hr at most wavelengths with peak-to-peak amplitudes between 1.45% and 5.3% of the mean flux. While the light curve shapes are similar at all wavelengths, their phases differ from wavelength to wavelength with a maximum difference of more than half of a rotational period. We compare the spectra with atmospheric models of different cloud prescriptions, from which we determine the pressure levels probed at different wavelengths. We find that the phase lag increases with decreasing pressure level, or higher altitude. We discuss a number of plausible scenarios that could cause this trend of light curve phase with probed pressure level. These observations are the first to probe heterogeneity in an ultracool atmosphere in both horizontal and vertical directions, and thus are an ideal test case for realistic three dimensional simulations of the atmospheric structure with clouds in brown dwarfs and extrasolar planets.Comment: Accepted to ApJL, 6 pages, 3 figures. Minor language updates from v1 to match published versio

Stabilization of a Failed Highway Slope: A Multi-Phased Approach

A county road department in Southeastern Michigan was faced with the problem of stabilizing a slope along the Clinton River supporting a heavily trafficked roadway. The roadway and supporting slope had performed satisfactorily for over 50 years. However, a reinforced concrete seawall that had partially supported the slope deteriorated over time, contributing to progressive failure of the slope and resulting damage to the roadway. The site is situated within the glacial lake plain district of Southeastern Michigan. The site geology consists of approximately 7 feet of over-consolidated clays underlain by approximately 17 feet of normally consolidated glacial-lacustrine clays. Below the normally consolidated clay, highly over-consolidated sandy clay till and dense fine to medium sands are present. The sands contain a confined aquifer with a hydrostatic head on the order of 20 feet. The 14-foot high, 35 degree slope has experienced progressive, creep type movement since approximately the year 2000 resulting in settlement and cracking of the roadway shoulder and pavement. Maintenance procedures to maintain serviceability of the roadway created increased surcharge loads that appear to have precipitated further creep movement. Our analyses indicated the unreinforced slope possessed a factor of safety of approximately one or less with respect to global and direct sliding failure mechanisms under both drained and undrained conditions. A number of alternatives were considered to obtain the desired factory of safety values. Upon analysis, these alternatives were not considered satisfactory due to failure to meet the project objectives, typically cost and/or failure to obtain the desired factor of safety against slope failure. A multi-phased approach was selected that was aimed at both reducing the destabilization forces as well as increasing the resisting forces by replacing the upper portion of the slope with geogrid-reinforced lightweight, angular blast furnace slag, and intercepting the slope failure surface with passive piles extending into the highly over-consolidated sandy clay till and/or dense sands. This approach allowed the project objective to be met with the work being accomplished on schedule and within budget. A cost savings of approximately $400,000 was realized with respect to other stabilization alternatives

Extrasolar StormsExtrasolar~Storms: Pressure-dependent Changes In Light Curve Phase In Brown Dwarfs From Simultaneous HubbleHubble and SpitzerSpitzer Observations

We present $Spitzer$/IRAC Ch1 and Ch2 monitoring of six brown dwarfs during 8 different epochs over the course of 20 months. For four brown dwarfs, we also obtained simulataneous $HST$/WFC3 G141 Grism spectra during two epochs and derived light curves in five narrow-band filters. Probing different pressure levels in the atmospheres, the multi-wavelength light curves of our six targets all exhibit variations, and the shape of the light curves evolves over the timescale of a rotation period, ranging from 1.4 h to 13 h. We compare the shapes of the light curves and estimate the phase shifts between the light curves observed at different wavelengths by comparing the phase of the primary Fourier components. We use state-of-the-art atmosphere models to determine the flux contribution of different pressure layers to the observed flux in each filter. We find that the light curves that probe higher pressures are similar and in phase, but are offset and often different from the light curves that probe lower pressures. The phase differences between the two groups of light curves suggest that the modulations seen at lower and higher pressures may be introduced by different cloud layers.Comment: 34 pages, 22 figures, accepted for publication in Ap

Weather on Other Worlds. I. Detection of Periodic Variability in the L3 Dwarf DENIS-P J1058.7-1548 with Precise Multi-wavelength Photometry

Photometric monitoring from warm Spitzer reveals that the L3 dwarf DENIS-P J1058.7-1548 varies sinusoidally in brightness with a period of 4.25^(+0.26)_(-0.16) hr and an amplitude of 0.388% ± 0.043% (peak-to-valley) in the 3.6 μm band, confirming the reality of a 4.31 ± 0.31 hr periodicity detected in J-band photometry from the SOAR telescope. The J-band variations are a factor of 2.17 ± 0.35 larger in amplitude than those at 3.6 μm, while 4.5 μm Spitzer observations yield a 4.5 μm/3.6 μm amplitude ratio of only 0.23 ± 0.15, consistent with zero 4.5 μm variability. This wide range in amplitudes indicates rotationally modulated variability due to magnetic phenomena and/or inhomogeneous cloud cover. Weak Hα emission indicates some magnetic activity, but it is difficult to explain the observed amplitudes by magnetic phenomena unless they are combined with cloud inhomogeneities (which might have a magnetic cause). However, inhomogeneous cloud cover alone can explain all our observations, and our data align with theory in requiring that the regions with the thickest clouds also have the lowest effective temperature. Combined with published vsin (i) results, our rotation period yields a 95% confidence lower limit of R_* ≥ 0.111 R_☉, suggesting upper limits of 320 Myr and 0.055 M_☉ on the age and mass. These limits should be regarded cautiously because of ~3σ inconsistencies with other data; however, a lower limit of 45° on the inclination is more secure. DENIS-P J1058.7-1548 is only the first of nearly two dozen low-amplitude variables discovered and analyzed by the Weather on Other Worlds project