Direct Detection of the Close Companion of Polaris with the Hubble Space Telescope

Polaris, the nearest and brightest classical Cepheid, is a single-lined spectroscopic binary with an orbital period of 30 years. Using the High Resolution Channel of the Advanced Camera for Surveys onboard the Hubble Space Telescope (HST) at a wavelength of ~2255\AA, we have directly detected the faint companion at a separation of 0\farcs17. A second HST observation 1.04 yr later confirms orbital motion in a retrograde direction. By combining our two measures with the spectroscopic orbit of Kamper and an analysis of the Hipparcos and FK5 proper motions by Wielen et al., we find a mass for Polaris Aa of 4.5^{+2.2}_{-1.4} M_\odot--the first purely dynamical mass determined for any Cepheid. For the faint companion Polaris Ab we find a dynamical mass of 1.26^{+0.14}_{-0.07} M_\odot, consistent with an inferred spectral type of F6 V and with the flux difference of 5.4 mag observed at 2255\AA. The magnitude difference at the V band is estimated to be 7.2 mag. Continued HST observations will significantly reduce the mass errors, which are presently still too large to provide critical constraints on the roles of convective overshoot, mass loss, rotation, and opacities in the evolution of intermediate-mass stars. Our astrometry, combined with two centuries of archival measurements, also confirms that the well-known, more distant (18") visual companion, Polaris B, has a nearly common proper motion with that of the Aa,Ab pair. This is consistent with orbital motion in a long-period bound system. The ultraviolet brightness of Polaris B is in accordance with its known F3 V spectral type if it has the same distance as Polaris Aa,Ab.Comment: 31 pages, 12 figures, 6 tables; accepted for publication in the Astronomical Journa

Retinoic acid as a modulator of T cell immunity

Indexación: Scopus. DOAJ.Vitamin A, a generic designation for an array of organic molecules that includes retinal, retinol and retinoic acid, is an essential nutrient needed in a wide array of aspects including the proper functioning of the visual system, maintenance of cell function and differentiation, epithelial surface integrity, erythrocyte production, reproduction, and normal immune function. Vitamin A deficiency is one of the most common micronutrient deficiencies worldwide and is associated with defects in adaptive immunity. Reports from epidemiological studies, clinical trials and experimental studies have clearly demonstrated that vitamin A plays a central role in immunity and that its deficiency is the cause of broad immune alterations including decreased humoral and cellular responses, inadequate immune regulation, weak response to vaccines and poor lymphoid organ development. In this review, we will examine the role of vitamin A in immunity and focus on several aspects of T cell biology such as T helper cell differentiation, function and homing, as well as lymphoid organ development. Further, we will provide an overview of the effects of vitamin A deficiency in the adaptive immune responses and how retinoic acid, through its effect on T cells can fine-tune the balance between tolerance and immunity.http://www.mdpi.com/2072-6643/8/6/34

The Effect of a Voice Treatment on Facial Expression in Parkinson’s Disease: Clinical and Demographic Predictors

Parkinson’s disease (PD) is a neurodegenerative disease associated with a wide range of motoric, cognitive, and behavioral symptoms. Impairments in facial mobility and emotional expressivity are common and can impair communication, in turn, affecting daily functioning and quality of life. Previous research suggests that the Lee Silverman Voice Treatment © (LSVT LOUD; Ramig et al., 2001, 2011) increases vocal loudness and facial expressivity in individuals with PD compared to PD and healthy controls. This study extends the literature by examining the effects of LSVT and an articulation-based control treatment (i.e., ARTIC) on multiple aspects of facial expressivity (i.e., emotional frequency [EF], emotional variability [EV], emotional intensity [EI], and social engagement [SE]) as well as non-emotional facial mobility (FM). Further, we examined whether demographic, clinical, cognitive, and affective variables predict facial expressivity and mobility improvement via LSVT. Participants included 40 individuals with idiopathic PD (67.5% male) and 14 demographically-matched healthy controls (60% male). The PD participants were randomly assigned to one of the following conditions: the LSVT LOUD treatment group (n = 13), a control therapy (Articulation Treatment [ARTIC]; n = 14), or an Untreated Control Condition (n = 13). All posers (PDs & HCs) were video-taped, before and after treatment (for the LSVT & ARTIC PD groups) or at baseline and after a 4-5 week waiting period for (for the Untreated PDs [UPDs] & HCs), while producing emotional (Happy, Sad, & Angry) monologues from the New York Emotion Battery (Borod et al., 1998; Borod, Welkowitz, & Obler, 1992). The monologues were randomized and divided into 15-second segments, and evaluated by 18 naïve raters for 4 different aspects of facial emotional expression and facial mobility. Separate training sessions were held for each of the five facial rating variables (i.e., FM, EF, EV, EI, & SE), and interrater reliability was largely in the high range. Findings revealed that PD posers displayed lower facial expressivity than HCs on three out of five variables, however, these effects were moderated by gender and emotion. In terms of gender, women were more expressive than men on all facial expression variables. Treatment results showed that individuals in the LSVT group showed significant improvements from pre- to post-treatment in facial expressivity for four out of the five variables examined (i.e., FM, EF, EV, & EI), however, for EV, this interaction was moderated by Gender, with significant increases from pre- to post-treatment for men but not for women in the LSVT group. There were no significant differences observed pre- to post-treatment for ARTIC or from baseline to 4-5 weeks later for the UPD and HC groups. In terms of predictive findings, demographic, clinical, cognitive, and affective variables did not predict facial improvement in LSVT participants, likely due to low power. This study has multiple clinical and research implications. First, we examined facial expression through a multifactorial approach, involving mobility, expressivity, and social judgment of others, which has not been done in other studies with PD and which may provide a better understanding of the specific facial impairments in PD. Clinically, our treatment findings for LSVT are important to the rehabilitation therapy literature, because there are very few empirically-validated treatments targeting facial emotional expressivity and facial mobility in individuals with PD

mRNA localization in metazoans: A structural perspective

This is the final version. Available on open access from Taylor & Francis via the DOI in this recordAsymmetric localization of mRNAs is a widespread gene regulatory mechanism that is crucial for many cellular processes. The localization of a transcript involves multiple steps and requires several protein factors to mediate transport, anchoring and translational repression of the mRNA. Specific recognition of the localizing transcript is a key step that depends on linear or structured localization signals, which are bound by RNA-binding proteins. Genetic studies have identified many components involved in mRNA localization. However, mechanistic aspects of the pathway are still poorly understood. Here we provide an overview of structural studies that contributed to our understanding of the mechanisms underlying mRNA localization, highlighting open questions and future challenges.The authors are funded by the Max Planck Gesellshaft, the European Research Council under the European Union's Seventh Framework Program (FP7/2007-2013), ERC grant agreement no. 310957 and the Deutsche Forschungsgemeinschaft (BO3588/2-1 to F.B.)

Galactic Cepheids with Spitzer: I. Leavitt Law and Colors

Classical Cepheid variable stars have been important indicators of extragalactic distance and Galactic evolution for over a century. The Spitzer Space Telescope has opened the possibility of extending the study of Cepheids into the mid- and far-infrared, where interstellar extinction is reduced. We have obtained photometry from images of a sample of Galactic Cepheids with the IRAC and MIPS instruments on Spitzer. Here we present the first mid-infrared period-luminosity relations for Classical Cepheids in the Galaxy, and the first ever Cepheid period-luminosity relations at 24 and 70 um. We compare these relations with theoretical predictions, and with period-luminosity relations obtained in recent studies of the Large Magellanic Cloud. We find a significant period-color relation for the [3.6]-[8.0] IRAC color. Other mid-infrared colors for both Cepheids and non-variable supergiants are strongly affected by variable molecular spectral features, in particular deep CO absorption bands. We do not find strong evidence for mid-infrared excess caused by warm (~500 K) circumstellar dust. We discuss the possibility that recent detections with near-infrared interferometers of circumstellar shells around delta Cep, l Car, Polaris, Y Oph and RS Pup may be a signature of shocked gas emission in a dust-poor wind associated to pulsation-driven mass loss.Comment: Accepted by The Astrophysical Journal on Nov 11, 200

Theoretical fits of the \delta Cephei light, radius and radial velocity curves

We present a theoretical investigation of the light, radius and radial velocity variations of the prototype $\delta$ Cephei. We find that the best fit model accounts for luminosity and velocity amplitudes with an accuracy better than $0.8\sigma$, and for the radius amplitude with an accuracy of $1.7\sigma$. The chemical composition of this model suggests a decrease in both helium (0.26 vs 0.28) and metal (0.01 vs 0.02) content in the solar neighborhood. Moreover, distance determinations based on the fit of light curves agree at the $0.8\sigma$ level with the trigonometric parallax measured by the Hubble Space Telescope (HST). On the other hand, distance determinations based on angular diameter variations, that are independent of interstellar extinction and of the $p$-factor value, indicate an increase of the order of 5% in the HST parallax.Comment: accepted for publication on ApJ Letter

Smoking behaviour and individual well-being: a fresh look at the effects of the 2005 public smoking ban in Italy

This paper investigates the impact of the public smoking ban which came into effect in Italy in January 2005 on individual smoking behaviour. Current empirical evidence supports the existence of a negative effect of the Italian ban on smoking prevalence and consumption in the general population. Our analysis shows that the apparent success of the ban is due to the fact that existing results do not take into account seasonal differences in smoking behaviour. Using quarterly data from the 1999/2000 and 2004/2005 Italian Health Surveys and adopting a difference-in-difference approach that nets out monthly variation in smoking rates, we show that the Italian smoking ban had no impact on smoking behaviour for the population as a whole but only on some subgroups. This result notwithstanding, we find that the smoking ban increased the overall well-being of non-smokers

New Evidence for Mass Loss from delta Cephei from HI 21-cm Line Observations

Recently published Spitzer observations of the classical Cepheid archetype delta Cephei revealed an extended dusty nebula surrounding this star and its hot companion. The infrared emission resembles a bow shock aligned with the direction of space motion of the star, indicating that delta Cep is undergoing mass-loss through a stellar wind. Here we report HI 21-cm line observations with the VLA to search for neutral atomic hydrogen associated with this wind. Our VLA data reveal a spatially extended HI nebula (~13' or 1 pc across) surrounding the position of delta Cep. The nebula has a head-tail morphology, consistent with circumstellar ejecta shaped by the interaction between a stellar wind and the ISM. We directly measure a mass of circumstellar hydrogen M_HI\approx0.07M_odot, although the total HI mass may be larger. The HI data imply a stellar wind with an outflow velocity V_o=35.6\pm1.2 km/s and a mass-loss rate of M_dot=(1.0\pm0.8)x10**-6 M_dot/yr. We have computed theoretical evolutionary tracks that include mass loss across the instability strip and show that a mass-loss rate of this magnitude, sustained over the preceding Cepheid lifetime of delta Cep, could be sufficient to resolve a significant fraction of the discrepancy between the pulsation and evolutionary masses for this star. (abridged)Comment: ApJ, in press (January 1, 2012). Version with full resolution figures available at http://www.haystack.mit.edu/hay/staff/lmatthew/matthews_deltaCep.pd

On the binarity of the classical Cepheid X Sgr from interferometric observations

Optical-infrared interferometry can provide direct geometrical measurements of the radii of Cepheids and/or reveal unknown binary companions of these stars. Such information is of great importance for a proper calibration of Period-Luminosity relations and for determining binary fraction among Cepheids. We observed the Cepheid X Sgr with VLTI/AMBER in order to confirm or disprove the presence of the hypothesized binary companion and to directly measure the mean stellar radius, possibly detecting its variation along the pulsation cycle. From AMBER observations in MR mode we performed a binary model fitting on the closure phase and a limb-darkened model fitting on the visibility. Our analysis indicates the presence of a point-like companion at a separation of 10.7 mas and 5.6 magK fainter than the primary, whose flux and position are sharply constrained by the data. The radius pulsation is not detected, whereas the average limb-darkened diameter results to be 1.48+/-0.08 mas, corresponding to 53+/-3 R_sun at a distance of 333.3 pc.Comment: 5 pages, 3 figures, research not

Statistical advances in epidemiology and public health

The key role of statistical modeling in epidemiology and public health is unquestionable [...]