Weak inter-band coupling in Mg10^{10}B2_{2}: a specific heat analysis

The superconducting state of Mg$^{10}$B$_{2}$ is investigated by specific heat measurements in detail. The specific heat in the normal state is analyzed using a recently developed computer code. This allows for an extraction of the electronic specific heat in the superconducting state with high accuracy and a fair determination of the main lattice features. One of the two investigated samples shows a hump in the specific heat at low temperatures within the superconducting state, accompanied by an unusual low value of the small gap, $\Delta_{\pi}(0)=1.32 meV$, pointing to a very weak inter-band coupling. This sample allows for a detailed analysis of the contribution from the $\pi$-band to the electronic specific heat in the superconducting state. Therefore the usual analysis method is modified, to include the individual conservation of entropy of both bands. From analyzing the deviation function $D(t)$ of MgB$_{2}$, the theoretically predicted weak inter-band coupling scenario is confirmed.Comment: major revision

A disrupted circumstellar torus inside eta Carinae's Homunculus Nebula

We present thermal infrared images of the bipolar nebula surrounding eta Carinae at six wavelengths from 4.8 to 24.5 microns. These were obtained with the MIRAC3 camera system at the Magellan Observatory. Our images reveal new intricate structure in the bright core of the nebula, allowing us to re-evaluate interpretations of morphology seen in images with lower resolution. Complex structures in the core might not arise from a pair of overlapping rings or a cool (110 K) and very massive dust torus, as has been suggested recently. Instead, it seems more likely that the arcs and compact knots comprise a warm (350 K) disrupted torus at the intersection of the larger polar lobes. Some of the arcs appear to break out of the inner core region, and may be associated with equatorial features seen in optical images. The torus could have been disrupted by a post-eruption stellar wind, or by ejecta from the Great Eruption itself if the torus existed before that event. Kinematic data are required to rule out either possibility.Comment: 8 pages, 3 figures (Fig. 1 in color); to appear in ApJ Letter

Concept to analyze the displacement time series of individual persistent scatterers

Persistent Scatterer Interferometry (PSInSAR) exploits a time series of Synthetic Aperture Radar (SAR) images to estimate the mean velocity with which the surface of the earth is deforming. However, most PSInSAR algorithms estimate the mean velocities using a linear regression model. Since some deformation phenomena can exhibit a more complex behavior over time, using a linear regression model leads to potentially wrong estimations for the mean velocity. For example, the velocity of a landslide moving down a steep slope can change depending on the water content of the material of the landslide, or an inactive landslide can reactivate due to an earthquake. Both scenarios would not result in a time series with a constant linear slope but in a piecewise linear time series. This paper presents a Matlab-based tool to analyze an individual Persistent Scatterer (PS) time series. The Persistent Scatterer Deformation Pattern Analysis Tool (PSDefoPAT) aims to build a mathematical model that sufficiently describes the time series trend and seasonal and noise components. The trend component is estimated using polynomial regression and piecewise linear models, while a sine function approximates the seasonal component. The goal is to identify the best fitting model for the displacement time series of a PS. PSDefoPAT is introduced by examine the time series of three different PS located in the region surrounding Patras, Greece. Based on the derived models, we discuss the nature of their deformation patterns

Spitzer Observations of Cold Dust Galaxies

We combine new Spitzer Space Telescope observations in the mid- and far-infrared with SCUBA 850 micron observations to improve the measurement of dust temperatures, masses and luminosities for 11 galaxies of the SCUBA Local Universe Galaxy Survey (SLUGS). By fitting dust models we measure typical dust masses of 10E7.9 M_sol and dust luminosities of ~ 10E10 L_sol, for galaxies with modest star formation rates. The data presented in this paper combined with previous observations show that cold dust is present in all types of spiral galaxies and is a major contributor to their total luminosity. Because of the lower dust temperature of the SCUBA sources measured in this paper, they have flatter Far-IR nu F_nu(160um)/nu F_nu(850um) slopes than the larger Spitzer Nearby Galaxies Survey (SINGS), the sample that provides the best measurements of the dust properties of galaxies in the nearby universe. The new data presented here added to SINGS extend the parameter space that is well covered by local galaxies, providing a comprehensive set of templates that can be used to interpret the observations of nearby and distant galaxies.Comment: Accepted by A.J. 16 pages, 10 figures, 7 tables. High resolution version at http://mips.as.arizona.edu/~cnaw/slugs_hires.pd

Differences in decision-making behavior between elite and amateur team-handball players in a near-game test situation

Athletic features distinguishing experts from non-experts in team sports are relevant for performance analyses, talent identification and successful training. In this respect, perceptual-cognitive factors like decision making have been proposed to be important predictor of talent but, however, assessing decision making in team sports remains a challenging endeavor. In particular, it is now known that decisions expressed by verbal reports or micro-movements in the laboratory differ from those actually made in on-field situations in play. To address this point, our study compared elite and amateur players' decision-making behavior in a near-game test environment including sport-specific sensorimotor responses. Team-handball players (N = 44) were asked to respond as quickly as possible to representative, temporally occluded attack sequences in a team-handball specific defense environment on a contact plate system. Specifically, participants had to choose and perform the most appropriate out of four prespecified, defense response actions. The frequency of responses and decision time were used as dependent variables representing decision-making behavior. We found that elite players responded significantly more often with offensive responses (p < 0.05, odds ratios: 2.76-3.00) in left-handed attack sequences. Decision time decreased with increasing visual information, but no expertise effect was found. We suppose that expertise-related knowledge and processing of kinematic information led to distinct decision-making behavior between elite and amateur players, evoked in a domain-specific and near-game test setting. Results also indicate that the quality of a decision might be of higher relevance than the required time to decide. Findings illustrate application opportunities in the context of performance analyses and talent identification processes

Absolute physical calibration in the infrared

We determine an absolute calibration for the Multiband Imaging Photometer for Spitzer 24 μm band and recommend adjustments to the published calibrations for Two Micron All Sky Survey (2MASS), Infrared Array Camera (IRAC), and IRAS photometry to put them on the same scale. We show that consistent results are obtained by basing the calibration on either an average A0V star spectral energy distribution (SED), or by using the absolutely calibrated SED of the Sun in comparison with solar-type stellar photometry (the solar analog method). After the rejection of a small number of stars with anomalous SEDs (or bad measurements), upper limits of ~1.5% root mean square (rms) are placed on the intrinsic infrared (IR) SED variations in both A-dwarf and solar-type stars. These types of stars are therefore suitable as general-purpose standard stars in the IR. We provide absolutely calibrated SEDs for a standard zero magnitude A star and for the Sun to allow extending this work to any other IR photometric system. They allow the recommended calibration to be applied from 1 to 25 μm with an accuracy of ~2%, and with even higher accuracy at specific wavelengths such as 2.2, 10.6, and 24 μm, near which there are direct measurements. However, we confirm earlier indications that Vega does not behave as a typical A0V star between the visible and the IR, making it problematic as the defining star for photometric systems. The integration of measurements of the Sun with those of solar-type stars also provides an accurate estimate of the solar SED from 1 through 30 μm, which we show agrees with theoretical models

Measuring the Stellar Masses of z~7 Galaxies with Spitzer Ultrafaint Survey Program (SURFS UP)

We present Spitzer/IRAC observations of nine $z'$-band dropouts highly magnified (2<mu<12) by the Bullet Cluster. We combine archival imaging with our Exploratory program (SURFS UP), which results in a total integration time of ~30 hr per IRAC band. We detect (>3sigma) in both IRAC bands the brightest of these high-redshift galaxies, with [3.6]=23.80+-0.28 mag, [4.5]=23.78+-0.25 mag, and (H-[3.6])=1.17+-0.32 mag. The remaining eight galaxies are undetected to [3.6]~26.4 mag and [4.5]~26.0 mag with stellar masses of ~5x10^7 M_sol. The detected galaxy has an estimated magnification of mu=12+-4, which implies this galaxy has an ultraviolet luminosity of L_1500~0.3 L*_{z=7} --- the lowest luminosity individual source detected in IRAC at z>7. By modeling the broadband photometry, we estimate the galaxy has an intrinsic star-formation rate of SFR~1.3 M_sol/yr and stellar mass of M~2x10^9 M_sol, which gives a specific star-formation rate of sSFR~0.7 Gyr^-1. If this galaxy had sustained this star-formation rate since z~20, it could have formed the observed stellar mass (to within a factor of ~2), we also discuss alternate star-formation histories and argue the exponentially-increasing model is unlikely. Finally, based on the intrinsic star-formation rate, we estimate this galaxy has a likely [C II] flux of = 10^{-17} erg/s/cm2.Comment: Accepted to ApJL. 6 pages, 3 figures, 2 table