Formation of the First Stars by Accretion

The process of star formation from metal-free gas is investigated by following the evolution of accreting protostars with emphasis on the properties of massive objects. The main aim is to establish the physical processes that determine the upper mass limit of the first stars. Although the consensus is that massive stars were commonly formed in the first cosmic structures, our calculations show that their actual formation depends sensitively on the mass accretion rate and its time variation. Even in the rather idealized case in which star formation is mainly determined by dot{M}acc, the characteristic mass scale of the first stars is rather uncertain. We find that there is a critical mass accretion rate dot{M}crit = 4 10^{-3} Msun/yr that separates solutions with dot{M}acc> 100 Msun can form, provided there is sufficient matter in the parent clouds, from others (dot{M}acc > dot{M}crit) where the maximum mass limit decreases as dot{M}acc increases. In the latter case, the protostellar luminosity reaches the Eddington limit before the onset of hydrogen burning at the center via the CN-cycle. This phase is followed by a rapid and dramatic expansion of the radius, possibly leading to reversal of the accretion flow when the stellar mass is about 100Msun. (abridged)Comment: 34 pages, 12 figures. ApJ, in pres

Vestibular neuritis: Vertigo and the high-acceleration vestibulo-ocular reflex

Abstract : Patients after vestibular neuritis (VN) often report persistent dizziness and disequilibrium. We correlated persistent symptoms with sustained impairment of the high-acceleration horizontal vestibulo-ocular reflex as determined by quantitative searchcoil head-impulse testing (qHIT). In 47 patients, qHIT was recorded 0-60 months and symptoms assessed with the Yardley Vertigo Symptom Scale short form ≥ 18 months after VN onset. No correlation between the magnitude of high-acceleration vestibular impairment and the severity of vertigo symptoms was observed. The lack of a symptom-qHIT correlation suggests that defective compensation at a more rostral level in the central nervous system may be responsible for protracted symptoms in VN patient

A case of labial fusion and urinary pseudo-incontinence in an elderly woman. A surgical treatment and a review

Labial fusion is defined as either partial or complete adherence of the labia minora (1), and also called vulvar fusion, adhesions of the labia minor or conglutination of the labia minora and sinechia of the vulva. The complete and severe labial fusion is a rare pathology with a small number of cases reported in the literature in adults. We present a case report of a postmenopausal woman who presented with voiding difficulty and incontinence and was treated by surgical division of the adhesions and immediate resolution of the urinary incontinence confirmed by multichannel urodynamic test postoperatively

A birth-death process for feature allocation

We propose a Bayesian nonparametric prior over feature allocations for sequential data, the birth-death feature allocation process (BDFP). The BDFP models the evolution of the feature allocation of a set of N objects across a covariate (e.g. time) by creating and deleting features. A BDFP is exchangeable, projective, stationary and reversible, and its equilibrium distribution is given by the Indian buffet process (IBP). We show that the Beta process on an extended space is the de Finetti mixing distribution underlying the BDFP. Finally, we present the finite approximation of the BDFP, the Beta Event Process (BEP), that permits simplified inference. The utility of the BDFP as a prior is demonstrated on real world dynamic genomics and social network dat

Elastic properties of hydrogenated graphene

There exist three conformers of hydrogenated graphene, referred to as chair-, boat-, or washboard-graphane. These systems have a perfect two-dimensional periodicity mapped onto the graphene scaffold, but they are characterized by a $sp^3$ orbital hybridization, have different crystal symmetry, and otherwise behave upon loading. By first principles calculations we determine their structural and phonon properties, as well as we establish their relative stability. Through continuum elasticity we define a simulation protocol addressed to measure by a computer experiment their linear and nonlinear elastic moduli and we actually compute them by first principles. We argue that all graphane conformers respond to any arbitrarily-oriented extention with a much smaller lateral contraction than the one calculated for graphene. Furthermore, we provide evidence that boat-graphane has a small and negative Poisson ratio along the armchair and zigzag principal directions of the carbon honeycomb lattice (axially auxetic elastic behavior). Moreover, we show that chair-graphane admits both softening and hardening hyperelasticity, depending on the direction of applied load.Comment: submitted on Phys.Rev.

A case of labial fusion and urinary pseudo-incontinence in an elderly woman. A surgical treatment and a review

Labial fusion is defined as either partial or complete adherence of the labia minora (1), and also called vulvar fusion, adhesions of the labia minor or conglutination of the labia minora and sinechia of the vulva. The complete and severe labial fusion is a rare pathology with a small number of cases reported in the literature in adults. We present a case report of a postmenopausal woman who presented with voiding difficulty and incontinence and was treated by surgical division of the adhesions and immediate resolution of the urinary incontinence confirmed by multichannel urodynamic test postoperatively

A multi-color optical survey of the orion nebula cluster. II. The H-R diagram

We present a new analysis of the stellar population of the Orion Nebula Cluster (ONC) based on multi-band optical photometry and spectroscopy.We study the color–color diagrams in BVI, plus a narrowband filter centered at 6200 Å, finding evidence that intrinsic color scales valid for main-sequence dwarfs are incompatible with the ONC in the M spectral-type range, while a better agreement is found employing intrinsic colors derived from synthetic photometry, constraining the surface gravity value as predicted by a pre-main-sequence isochrone.We refine these model colors even further, empirically, by comparison with a selected sample of ONC stars with no accretion and no extinction. We consider the stars with known spectral types from the literature, and extend this sample with the addition of 65 newly classified stars from slit spectroscopy and 182 M-type from narrowband photometry; in this way, we isolate a sample of about 1000 stars with known spectral type. We introduce a new method to self-consistently derive the stellar reddening and the optical excess due to accretion from the location of each star in the BVI color–color diagram. This enables us to accurately determine the extinction of the ONC members, together with an estimate of their accretion luminosities. We adopt a lower distance for the Orion Nebula than previously assumed, based on recent parallax measurements. With a careful choice of also the spectral-type–temperature transformation, we produce the new Hertzsprung–Russell diagram of the ONC population, more populated than previous works. With respect to previous works, we find higher luminosity for late-type stars and a slightly lower luminosity for early types. We determine the age distribution of the population, peaking from ~2 to ~3 Myr depending on the model. We study the distribution of the members in the mass–age plane and find that taking into account selection effects due to incompleteness, removes an apparent correlation between mass and age.We derive the initial mass function for low- and intermediate mass members of the ONC, which turns out to be model dependent and shows a turnover at M ≲ 0.2 M_⊙

Vestibular and auditory deficits in Fabry disease and their response to enzyme replacement therapy

Progressive hearing (pHL) and vestibular (pVL) loss are frequent deficits in Fabry disease (FD). Recently, enzyme replacement therapy (ERT) with human α-galactosidase A has become available. Here, we investigate the association between pHL and pVL in FD and their ERT responses. Pure tone audiometry (PTA) and head impulse testing (HIT) were administered at baseline in 47 patients (25 male, 18-0 y; 22 female, 17-4 y), of whom 24 also received caloric irrigation (CI). Of the 47 patients, 38 (24 male) were tested both before and during ERT (follow- up ≤60 months). ERT consisted of agalsidase alfa infusions. At baseline, pHL was present in 88% of males and 86% of females. Over all tested frequencies (range: 0.5- kHz), pHL was significantly (two-way ANOVA: p 0.05). We conclude that pHL and pVL prevalences are similar in FD. To detect pVL, HIT is more sensitive than CI. We speculate that pHL and pVL emerge from lesions within the vestibulocochlear labyrinth, because no specific patterns of vestibulo-cochlear deficits were observed, as expected if lesions were more proximal along the inferior or superior branch of the vestibulo-cochlear nerve or labyrinthine artery. Finally, ERT stabilizes auditory and even improves vestibular functio

Ambulatory Care Skills: Do Residents Feel Prepared?

Abstract: Objective: To determine resident comfort and skill in performing ambulatory care skills. Methods: Descriptive survey of common ambulatory care skills administered to internal medicine faculty and residents at one academic medical center. Respondents were asked to rate their ability to perform 12 physical exam skills and 6 procedures, and their comfort in performing 7 types of counseling, and obtaining 6 types of patient history (4 point Likert scale for each). Self-rated ability or comfort was compared by gender, status (year of residency, faculty), and future predicted frequency of use of the skill. Results: Residents reported high ability levels for physical exam skills common to both the ambulatory and hospital setting. Fewer felt able to perform musculoskeletal, neurologic or eye exams easily alone. Procedures generally received low ability ratings. Similarly, residents’ comfort in performing common outpatient counseling was also low. More residents reported feeling very comfortable in obtaining history from patients. We found little variation by gender, year of training, or predicted frequency of use. Conclusion: Self-reported ability and comfort for many common ambulatory care skills is low. Further evaluation of this finding in other training programs is warranted