Thermodynamic evidence for valley-dependent density of states in bulk bismuth

Electron-like carriers in bismuth are described by the Dirac Hamiltonian, with a band mass becoming a thousandth of the bare electron mass along one crystalline axis. The existence of three anisotropic valleys offers electrons an additional degree of freedom, a subject of recent attention. Here, we map the Landau spectrum by angle-resolved magnetostriction, and quantify the carrier number in each valley: while the electron valleys keep identical spectra, they substantially differ in their density of states at the Fermi level. Thus, the electron fluid does not keep the rotational symmetry of the lattice at low temperature and high magnetic field, even in the absence of internal strain. This effect, reminiscent of the Coulomb pseudo-gap in localized electronic states, affects only electrons in the immediate vicinity of the Fermi level. It presents the most striking departure from the non-interacting picture of electrons in bulk bismuth.Comment: 6 pages, 3 Figure

Wiedemann-Franz law and non-vanishing temperature scale across the field-tuned quantum critical point of YbRh2Si2

The in-plane thermal conductivity kappa(T) and electrical resistivity rho(T) of the heavy-fermion metal YbRh2Si2 were measured down to 50 mK for magnetic fields H parallel and perpendicular to the tetragonal c axis, through the field-tuned quantum critical point, Hc, at which antiferromagnetic order ends. The thermal and electrical resistivities, w(T) and rho(T), show a linear temperature dependence below 1 K, typical of the non-Fermi liquid behavior found near antiferromagnetic quantum critical points, but this dependence does not persist down to T = 0. Below a characteristic temperature T* ~ 0.35 K, which depends weakly on H, w(T) and rho(T) both deviate downward and converge in the T = 0 limit. We propose that T* marks the onset of short-range magnetic correlations, persisting beyond Hc. By comparing samples of different purity, we conclude that the Wiedemann-Franz law holds in YbRh2Si2, even at Hc, implying that no fundamental breakdown of quasiparticle behavior occurs in this material. The overall phenomenology of heat and charge transport in YbRh2Si2 is similar to that observed in the heavy-fermion metal CeCoIn5, near its own field-tuned quantum critical point.Comment: 8 figures, 8 page

University Image and its Relationship to Student Satisfaction: Case of the Holy Spirit University of Kaslik, Lebanon

This work focuses on the study of the university’s image with the aim of explaining the components of image and attributes of student satisfaction. Our study investigates the relationships between the different components of the university image and to what extent they may affect the students’ satisfaction. Hypotheses were drawn setting the relationships between the affective, cognitive and overall image in relation with satisfaction. The results of the empirical work carried out on a representative sample of 200 students studying at Holy Spirit University of Kaslik (USEK) demonstrate that the cognitive component of image is an antecedent of the affective component. In turn, both of these components influence the formation of the overall image of a university. However, the affective and overall images statistically and significantly affect the overall satisfaction of students with their university. The research could also be extended to cover the area of the Middle East and study the process of formation of the university image by various public universities

Premixed edge-flames under transverse enthalpy gradients

We describe flame propagation between two opposed reactive streams which may differ in their composition and temperature. A two-dimensional counterflow configuration and an irreversible Arrhenius reaction are adopted, along with the constant density approximation. Attention is focused on the influence of two nondimensional parameters. The first one, denoted by γ, represents the difference in the enthalpy of the feed streams. The second one, ε, quantifies the ratio between the characteristic chemical time and the strain time. After a general formulation of the problem, we begin by an analysis of the one-dimensional case consisting of two parallel planar flames of unequal strength. The flames behavior is described analytically and numerically. In particular, two extinction regimes are identified: for values of γ smaller than a critical value γ*, the flames extinguish by quenching against each other at the stagnation plane; for γ > γ* they extinguish while at a finite distance from each other which increases with γ. These behaviors are similar to those, known in the literature, associated with the influence of Lewis numbers on the extinction of twin-flames. We then describe the propagation of two-dimensional flame fronts along the stagnation line, in a direction perpendicular to the plane of strain. The flame front is thus curved under the combined effects of the flow field and the transverse enthalpy gradient in the frozen mixture ahead of it; far behind the state of the gas is that of the pair of flat flames introduced above. The problem is studied numerically and complemented by an analytical description of the fast-chemistry situations corresponding to small values of ε. In particular we describe, for different fixed values of γ, the evolution of ignition fronts, characterized by a positive propagation speed, to extinction fronts, characterized by negative speeds, as ε is increased. In addition to the marked change in the flame shape, the most noticeable effect of an increase in γ is the decrease in the propagation speed of the flame front. These effects are associated with the increased front curvature for higher values of γ, along with a shift of the front leading edge towards the stream with higher enthalpy

Syndrome D’aniridie Associé À La Dermatite Atopique: À Propos D’un Cas

Aniridia syndrome is a genetic anomaly affecting all ocular structures; it is transmitted by an autosomal dominant mode. In its isolated form aniridia is characterized by a hypoplasia of the iris frequently associated with other ocular anomalies. It the syndromic form it is associated to other systemic abnormalities. Authors are here reporting a case of aniridia associating: a corneal pannus, total aniridia, lens ectopia, and cataract found in a 14 years old girl. She also presented an atopic background with a positive family history of atopia. She is issued from a first degree consanguineous marriage. The management was multidisciplinary. In ophthalmology she underwent an intra-capsular extraction of the lens in both eyes with no intra-ocular lens implantation. Dermatological management was treatment of cuteanous lesions with emollients, corticoids and antihistamines drugs and ointments

Atteintes Oculaires Au Cours Du Syndrome De Wolfram À Propos De Deux Cas Et Revue De La Littérature

Introduction: Wolfram syndrome is an autosomal recessive neurodegenerative disorder. Diabetes mellitus and juvenile bilateral optic atrophy are its major signs. It is recognized that this association, which started in childhood or during adolescence, is sufficient to diagnose Wolfram syndrome. Optic atrophy occurs in 98% to 100% of cases with an average age of onset of 11 years. We reported a study of two confirmed cases referred by the internal medicine department. Observations: Case 1: A 23- year-old woman, deaf and dumb by birth, went through a diabetic ketosis test. Ophthalmologic examination showed reduced visual acuity in the fingers at 5 meters P2 in both eyes. Also, the fundus of the eye showed bilateral atrophic papillary palpation with no signs of retinopathy. She had deafness of deep perception and hypogonadotropic hypogonadism. Deafness, diabetes, optic atrophy, and hypogonadism led to the diagnosis. Case 2: A 21-year-old man born from a first-degree consanguineous marriage serves as a supplement to the management of diabetes. The visual acuity was at counting fingers at 1m to the right eye and sees the hand move to 0.5 m to the left eye. On examination at the slit lamp, it had a bilateral dense cataract. After phacoexeresis, the base revealed bilateral optic atrophy. Ultrasound of the urinary tree showed hypotonia of the renal cavities and a neurogenic bladder. Also, audiometry showed mild sensory deafness. The diagnosis of Wolfram syndrome was made in front of the tetrad: diabetes, optic atrophy, deafness, and urinary signs. Discussion: Wolfram syndrome may be familial or sporadic. The gene however is located on the short arm of chromosome 4. Optic atrophy is secondary to the involvement of pre-genetic fibers, and it is characterized initially by temporal palpation of the papilla. The evolution towards diffuse whitish discoloration occurs in a few months or years with the gradual establishment of a blindness around the age of 17 to 30 years. Conclusion: Wolfram syndrome is a clinical entity characterized by clinical and genetic polymorphism. This diagnosis should be considered in the presence of any type I diabetes associated with optic atrophy in childre

Cascade of magnetic field induced Lifshitz transitions in the ferromagnetic Kondo lattice material YbNi4P2

A ferromagnetic quantum critical point is thought not to exist in two and three-dimensional metallic systems yet is realized in the Kondo lattice compound YbNi4(P,As)2, possibly due to its one-dimensionality. It is crucial to investigate the dimensionality of the Fermi surface of YbNi4P2 experimentally but common probes such as ARPES and quantum oscillation measurements are lacking. Here, we studied the magnetic field dependence of transport and thermodynamic properties of YbNi4P2. The Kondo effect is continuously suppressed and additionally we identify nine Lifshitz transitions between 0.4 and 18 T. We analyze the transport coefficients in detail and identify the type of Lifshitz transitions as neck or void type to gain information on the Fermi surface of YbNi4P2. The large number of Lifshitz transitions observed within this small energy window is unprecedented and results from the particular flat renormalized band structure with strong 4f-electron character shaped by the Kondo lattice effect.Comment: 6 pages, 4 figure

Lymphome Cérébral Primitif (LCP) du Sujet Immunocompétent: A Propos d’Un cas à l’Hôpital National de Niamey (HNN)

Le Lymphome Cérébral Primitif (LCP) du sujet immunocompétent est une entité rare des lymphomes Non Hodgkiniens en général et des tumeurs cérébrales en particulier. Il est caractérisé par sa sévérité clinique, mais aussi son mauvais pronostic. Nous rapportons un cas de LCP chez un sujet immunocompétent diagnostiqué au service de neurologie et pris en charge au service d’Onco-hématologie de l’Hôpital National de Niamey.   Primary Cerebral Lymphoma (PCL) of the immunocompetent subject is a rare feature of non-Hodgkin's lymphoma in general and brain tumors in particular. It is characterized by its clinical severity, but also its poor prognosis. We report a case of LCP in an immunocompetent subject diagnosed in the neurology department and managed by Onco-hematology at the National Hospital of Niamey

Geriatric in Patient Profile at the Department of Internal Medicine at Niamey National Hospital, Niger

Background: The ageing population in developing countries has brought a demographic and an epidemiological transition, with the impact of chronic diseases resulting from life style changes on the health status of the population. Objective: To describ a profile geriatrics patient, specifically to identify epidemiologic, clinical, etiologic and outcome of this group at the department of internal medicine to NNH Patients and method: Medical records of all geriatric patients aged ≥65 years admitted at the department of NNH Between January 2012 and December 2015 were retrieved and reviewed retrospectively. Results: A total of 6074 admissions at the internal medicine department of NNH over three years were reported and 1130 (18, 6%) were geriatrics patients, the average age was 75, 95 years and more than half were men (50,7%). 80 % of patients were in the young old group (65-74 years), 13% in the old group (75-84 years) and 7% in the oldest old group (≥85 years). High blood pressure was the frequent comorbidity (12, 3%) and the most symptoms caused hospitalization were stroke (17, 6%), fevers (16, 5%) and worst health (13, 1%). Frequent illnesses were cardiovascular diseases (38.4%), infections, (19.2%) and endocrine diseases (11%). The average length of hospital stays was 8, 7 days. The mortality rate was 18, 2% and the worst outcomes factors were female sex, frail elderly group in 75 to 84 years and high blood pressure. Conclusion: Chronic diseases were responsible of morbidity and mortality for the majority elderly’s patient