New clinical practice guideline on enteral feeding in very low birth weight infants: second part

Introduction: The nutrition of very low birth weight (VLBW) infants is aimed at promoting a similar growth to that occurring in the uterus. However, in practice this is difficult to achieve and extrauterine growth restriction is frequent. The current tendency is to avoid this restriction by means of early parenteral and enteral nutrition. Nonetheless, uncertainty about many of the practices related with nutrition has resulted in a great variation in the way it is undertaken. In 2009 and 2011 in our hospital there was an unexpected increase in necrotizing enterocolitis. To check to see wether our nutrition policy was involved, we underlook a systematic review and drewup clinical practice guidelines (CPG) about enteral feeding in VLBW infants. New considerations about the duration of the fortification and the use of probiotics have led to an update of these CPG. Methods: A total of 21 clinical questions were designed dealing with the type of milk, starting age, mode of administration, rate and volume of the increments, fortification, use of probiotics and protocol. Afete conducting a systematic search of the available evidence, the information was contrasted and summarized in order to draw up the recommendations. The quality of the evidence and the strength of the recommendations were determined from the SIGN scale. Comment: These CPG aim to help physicians in their decision making. The protocolized application of well-proven measurements reduces the variation in clinical practice and improves results.

Anthropometric indicators of nutritional status and growth in very low birth-weight premature infants hospitalized in a neonatal intensive care unit

Background: Anthropometric indicators are difficult to interpret in very low birth weight (VLBW) premature infants, including both appropriate for gestational age (AGA) and small for gestational age (SGA) infants. Therefore, the purpose was to describe the anthropometric indicators of growth and nutritional status in VLBW premature infants AGA and SGA, hospitalized in a neonatal intensive care unit (NICU). Study design: The descriptive and prospective study design included 114 preterm infants, adequate for gestational age/small for gestational age hospitalized in the intensive care unit. Head, thigh, mid upper arm circumference, skin-fold measurements and weight/age, length/ age, and weight/length indices were obtained. Correlations were made among the anthropometric indices, and a multivariate regression analysis with weight/age as dependent variable was performed. Results: Weight/age in AGA premature infants had high number of significant anthropometric correlations. The SGA premature infants had few and weak correlations. The regression analysis showed that anthropometric indices better explain changes in the weight/age index in adequate for gestational age premature infants. Conclusion: Weight/age in the VLBW/AGA premature infants could reflect growth, nutritional status and energy stored as fat, but in the VLBW/SGA premature infants, thigh circumference and mid arm circumference would be better indicators just of nutritional status.

Antibiotic Therapy for Very Low BirthWeigh Newborns in NICU

Background: Prolonged empiric antibiotics therapy in neonates results in several adverse consequences including widespread antibiotic resistance, late onset sepsis (LOS), necrotizing enterocolitis (NEC), prolonged hospital course (HC) and increase in mortality rates. Objectives: To assess the risk factors and the outcome of prolonged empiric antibiotic therapy in very low birth weight (VLBW) newborns. Materials and Methods: Prospective study in VLBW neonates admitted to NICU and survived > 2 W, from July 2011 - June 2012. All relevant perinatal and postnatal data including duration of antibiotics therapy (Group I < 2W vs Group II > 2W) and outcome up to the time of discharge or death were documented and compared. Results: Out of 145 newborns included in the study, 62 were in group I, and 83 in Group II. Average duration of antibiotic therapy was 14 days (range 3 - 62 days); duration in Group I and Group II was 102.3 vs 25.510.5 days. Hospital stay was 22.311.5 vs 44.3 14.7 days, respectively. Multiple regression analysis revealed following risk factors as significant for prolonged empiric antibiotic therapy: VLBW especially < 1000 g, (P < 0.001), maternal Illness (P = 0.003), chorioamnionitis (P = 0.048), multiple pregnancy (P = 0.03), non-invasive ventilation (P < 0.001) and mechanical ventilation (P < 0.001). Seventy (48.3%) infants developed LOS; 5 with NEC > stage II, 12 (8.3%) newborns died. Infant mortality alone and with LOS/NEC was higher in group II as compared to group I (P < 0.002 and < 0.001 respectively). Conclusions: Prolonged empiric antibiotic therapy caused increasing rates of LOS, NEC, HC and infant mortality

Very low risk ST-segment elevation myocardial infarction? It exists and may be easily identified

Early discharge protocols have been proposed for ST-segment elevation myocardial infarction (STEMI) low risk patients despite the existence of few but significant cardiovascular events during mid-term follow-up. We aimed to identify a subgroup of patients among those considered low-risk in which prognosis would be particularly good. We analyzed 30-day outcomes and long-term follow-up among 1.111 STEMI patients treated with reperfusion therapy. Multivariate analysis identified seven variables as predictors of 30-day outcomes: Femoral approach; age > 65; systolic dysfunction; postprocedural TIMI flow < 3; elevated creatinine level > 1.5 mg/dL; stenosis of left-main coronary artery; and two or higher Killip class (FASTEST). A total of 228 patients (20.5%), defined as very low-risk (VLR), had none of these variables on admission. VLR group of patients compared to non-VLR patients had lower in-hospital (0% vs. 5.9%; p < 0.001) and 30-day mortality (0% vs. 6.25%: p < 0.001). They also presented fewer in-hospital complications (6.6% vs. 39.7%; p < 0.001) and 30-day major adverse events (0.9% vs. 4.5%; p = 0.01). Significant mortality differences during a mean follow-up of 23.8 ± 19.4 months were also observed (2.2% vs. 15.2%; p < 0.001). The first VLR subject died 11 months after hospital discharge. No cardiovascular deaths were identified in this subgroup of patients during follow-up. About a fifth of STEMI patients have VLR and can be easily identified. They have an excellent prognosis suggesting that 24–48 h in-hospital stay could be a feasible alternative in these patients.

Graphene as a sensor

Graphene has emerged as one of the strongest candidates for post-silicon technologies. One of the most important applications of graphene in the foreseeable future is sensing of particles of gas molecules, biomolecules or different chemicals or sensing of radiation of particles like alpha, gamma or cosmic particles. Several unique properties of graphene such as its extremely small thickness, very low mass, large surface to volume ratio, very high absorption coefficient, high mobility of charge carriers, high mechanical strength and high Young's modulus make it exceptionally suitable for making sensors. In this article we review the state-of-the-art in the application of graphene as a material and radiation detector, focusing on the current experimental status, challenges and the excitement ahead.

An Approximate Method For Calculation Of Fluid Force And Response Of A Circular Cylinder At Lock-In

In this paper, equations calculating lift force of a rigid circular cyclinder at lock-in uniform flow are deduced in detail. Besides, equations calculating the lift force on a long flexible circular cyclinder at lock-in are deduced based on mode analysis of a multi-degree freedom system. The simplified forms of these equations are also given. Furthermore, an approximate method to predict the forces and response of rigid circular cyclinders and long flexible circular cyclinders at lock-in is introduced in the case of low mass-damping ratio. A method to eliminate one deficiency of these equations is introduced. Comparison with experimental results show the effectiveness of this approximate method.

Physical Modeling And Parametric Study On Two-Degree-Of-Freedom Viv Of A Cylinder Near Rigid Wall

Unlike most previous studies on the transverse vortex-induced vibration(VIV) of a cylinder mainly under the wallfree condition (Williamson & Govardhan,2004),this paper experimentally investigates the vortex-induced vibration of a cylinder with two degrees of freedom near a rigid wall exposed to steady flow.The amplitude and frequency responses of the cylinder are discussed.The lee wake flow patterns of the cylinder undergoing VIV were visualized by employing the hydrogen bubble technique.The effects of the gap-to-diameter ratio (e0/D) and the mass ratio on the vibration amplitude and frequency are analyzed.Comparisons of VIV response of the cylinder are made between one degree (only transverse) and two degrees of freedom (streamwise and transverse) and those between the present study and previous ones.The experimental observation indicates that there are two types of streamwise vibration,i.e.the first streamwise vibration (FSV) with small amplitude and the second streamwise vibration (SSV) which coexists with transverse vibration.The vortex shedding pattem for the FSV is approximately symmetric and that for the SSV is alternate.The first streamwise vibration tends to disappear with the decrease of e0/D.For the case of large gap-to-diameter ratios (e.g.e0/D = 0.54～1.58),the maximum amplitudes of the second streamwise vibration and transverse one increase with the increasing gapto-diameter ratio.But for the case of small gap-to-diameter ratios (e.g.e0/D = 0.16,0.23),the vibration amplitude of the cylinder increases slowly at the initial stage (i.e.at small reduced velocity V,),and across the maximum amplitude it decreases quickly at the last stage (i.e.at large Vr).Within the range ofthe examined small mass ratio (m＜4),both streamwise and transverse vibration amplitude of the cylinder decrease with the increase of mass ratio for the fixed value of V,.The vibration range (in terms of Vr ) tends to widen with the decrease of the mass ratio.In the second streamwise vibration region,the vibration frequency of the cylinder with a small mass ratio (e.g.mx = 1.44) undergoes a jump at a certain Vr,.The maximum amplitudes of the transverse vibration for two-degree-of-freedom case is larger than that for one-degree-of-freedom case,but the transverse vibration frequency of the cylinder with two degrees of freedom is lower than that with one degree of freedom (transverse).

Experimental Study Of Vortex-Induced Vibrations Of A Cylinder Near A Rigid Plane Boundary In Steady Flow

In this study, the vortex-induced vibrations of a cylinder near a rigid plane boundary in a steady flow are studied experimentally. The phenomenon of vortex-induced vibrations of the cylinder near the rigid plane boundary is reproduced in the flume. The vortex shedding frequency and mode are also measured by the methods of hot film velocimeter and hydrogen bubbles. A parametric study is carried out to investigate the influences of reduced velocity, gap-to-diameter ratio, stability parameter and mass ratio on the amplitude and frequency responses of the cylinder. Experimental results indicate: (1) the Strouhal number (St) is around 0.2 for the stationary cylinder near a plane boundary in the sub-critical flow regime; (2) with increasing gap-to-diameter ratio (e (0)/D), the amplitude ratio (A/D) gets larger but frequency ratio (f/f (n) ) has a slight variation for the case of larger values of e (0)/D (e (0)/D > 0.66 in this study); (3) there is a clear difference of amplitude and frequency responses of the cylinder between the larger gap-to-diameter ratios (e (0)/D > 0.66) and the smaller ones (e (0)/D < 0.3); (4) the vibration of the cylinder is easier to occur and the range of vibration in terms of V (r) number becomes more extensive with decrease of the stability parameter, but the frequency response is affected slightly by the stability parameter; (5) with decreasing mass ratio, the width of the lock-in ranges in terms of V (r) and the frequency ratio (f/f (n) ) become larger.

EL CVn-type binaries - Discovery of 17 helium white dwarf precursors in bright eclipsing binary star systems

The star 1SWASP J024743.37-251549.2 was recently discovered to be a binary star in which an A-type dwarf star eclipses the remnant of a disrupted red giant star (WASP 0247-25 B). The remnant is in a rarely observed state evolving to higher effective temperatures at nearly constant luminosity prior to becoming a very low mass white dwarf composed almost entirely of helium, i.e. it is a pre-helium white dwarf (pre-He-WD). We have used the photometric database from theWide Angle Search for Planets (WASP) to find 17 eclipsing binary stars with orbital periods P = 0.7-2.2 d with similar light curves to 1SWASP J024743.37-251549.2. The only star in this group previously identified as a variable star is the brightest one, EL CVn, which we adopt as the prototype for this class of eclipsing binary star. The characteristic light curves of EL CVn-type stars show a total eclipse by an A-type dwarf star of a smaller, hotter star and a secondary eclipse of comparable depth to the primary eclipse. We have used new spectroscopic observations for six of these systems to confirm that the companions to the A-type stars in these binaries have very low masses (≈0.2M⊙). This includes the companion to EL CVn which was not previously known to be a pre-He-WD. EL CVn-type binary star systems will enable us to study the formation of very low mass white dwarfs in great detail, particularly in those cases where the pre-He-WD star shows non-radial pulsations similar to those recently discovered in WASP0247-25 B. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

Quiescent and flaring X-ray emission from the nearby M/T dwarf binary SCR 1845-6357

Aims: X-ray emission is an important diagnostics to study magnetic activity in very low mass stars that are presumably fully convective and have an effectively neutral photosphere. Methods: We investigate an XMM-Newton observation of SCR 1845-6357, a nearby, ultracool M 8.5 / T 5.5 dwarf binary. The binary is unresolved in the XMM detectors, but the X-ray emission is very likely from the M 8.5 dwarf. We compare its flaring emission to those of similar very low mass stars and additionally present an XMM observation of the M 8 dwarf VB 10. Results: We detect quasi-quiescent X-ray emission from SCR 1845-6357 at soft X-ray energies in the 0.2-2.0 keV band, as well as a strong flare with a count rate increase of a factor of 30 and a duration of only 10 min. The quasi-quiescent X-ray luminosity of log LX = 26.2 erg/s and the corresponding activity level of log LX/Lbol = -3.8 point to a fairly active star. Coronal temperatures of up to 5 MK and frequent minor variability support this picture. During the flare, which is accompanied by a significant brightening in the near-UV, plasma temperatures of 25-30 MK are observed and an X-ray luminosity of LX = 8 × 1027 erg/s is reached. Conclusions: The source SCR 1845-6357 is a nearby, very low mass star that emits X-rays at detectable levels in quasi-quiescence, implying the existence of a corona. The high activity level, coronal temperatures and the observed large flare point to a rather active star, despite its estimated age of a few Gyr.

Where are the mid-sized flares of ultracool M dwarfs?

We propose to observe the M8.5 dwarf SCR J1845-6357 with XMM-Newton EPIC for 60 ks. Very low-mass M dwarfs show a distinct drop in X-ray luminosity compared to slightly more massive M dwarfs. Surprisingly, this does not happen at the mass threshold where M dwarfs become fully convective (M4), but at significantly lower masses (M8). These very low mass stars seem to have a flaring behaviour different from earlier type stars: they display either occasional large flares or a very low-level "flickering" in their X-ray light curves, but not the canonical power-law flare-energy distribution observed for the Sun and other cool stars. Our aim is to collect a long-duration light curve for one of the most nearby ultracool dwarfs to quantify how its flare-energy distribution differs from earlier type stars.

Recherche et caractérisation de systèmes binaires dont l'une des composantes est de faible masse

Nous présentons la découverte de quatorze nouveaux systèmes binaires ayant une séparation supérieure à 250 UA et dont au moins l'une des composantes est une naine M ou une naine L. Ces systèmes ont d'abord été identifiés en cherchant des objets ayant un mouvement propre commun autour d'étoiles connues possédant un mouvement propre élevé, grâce à une corrélation croisée de grands relevés du ciel dans l'infrarouge proche (2MASS, SDSS et SIMP). Un suivi astrométrique, afin de confirmer le mouvement propre commun, a été réalisé sur toutes les cibles avec la caméra SIMON et/ou la caméra CPAPIR à l'Observatoire du Mont-Mégatic (OMM) ou à l'Observatoire interaméricain du Cerro Tololo (CTIO). Un suivi spectroscopique a aussi été effectué sur la plupart des compagnons avec GMOS ou GNIRS à Gemini afin de déterminer leurs types spectraux. La probabilité que deux objets forment un système binaire par hasard a été évaluée afin de s'assurer que les couples candidats que nous présentons soient réellement liés.Un de nos nouveaux systèmes a un compagnon de masse sous-stellaire : 2M1259+1001 (L4.5). L'étude des systèmes que nous avons découverts pourra, entre autre, nous aider à mieux comprendre les mécanismes de formation des étoiles de très faible masse et des naines brunes.

La recherche de naines brunes et étoiles de faible masse dans les associations cinématiques jeunes du voisinage solaire

L’objectif principal de cette thèse est d’identifier les étoiles de faible masse et naines brunes membres d’associations cinématiques jeunes du voisinage solaire. Ces associations sont typiquement âgées de moins de 200 millions d’années et regroupent chacune un ensemble d’étoiles s’étant formées au même moment et dans un même environnement. La majorité de leurs membres d'environ plus de 0.3 fois la masse du Soleil sont déjà connus, cependant les membres moins massifs (et moins brillants) nous échappent encore. Leur identification permettra de lever le voile sur plusieurs questions fondamentales en astrophysique. En particulier, le fait de cibler des objets jeunes, encore chauds et lumineux par leur formation récente, permettra d’atteindre un régime de masses encore peu exploré, jusqu'à seulement quelques fois la masse de Jupiter. Elles nous permettront entre autres de contraindre la fonction de masse initiale et d'explorer la connection entre naines brunes et exoplanètes, étant donné que les moins massives des naines brunes jeunes auront des propriétés physiques très semblables aux exoplanètes géantes gazeuses. Pour mener à bien ce projet, nous avons adapté l'outil statistique BANYAN I pour qu'il soit applicable aux objets de très faibles masses en plus de lui apporter plusieurs améliorations. Nous avons entre autres inclus l'utilisation de deux diagrammes couleur-magnitude permettant de différencier les étoiles de faible masse et naines brunes jeunes à celles plus vieilles, ajouté l'utilisation de probabilités a priori pour rendre les résultats plus réalistes, adapté les modèles spatiaux et cinématiques des associations jeunes en utilisant des ellipsoïdes gaussiennes tridimensionnelles dont l'alignement des axes est libre, effectué une analyse Monte Carlo pour caractériser le taux de faux-positifs et faux-négatifs, puis revu la structure du code informatique pour le rendre plus efficace. Dans un premier temps, nous avons utilisé ce nouvel algorithme, BANYAN II, pour identifier 25 nouvelles candidates membres d'associations jeunes parmi un échantillon de 158 étoiles de faible masse (de types spectraux > M4) et naines brunes jeunes déjà connues. Nous avons ensuite effectué la corrélation croisée de deux catalogues couvrant tout le ciel en lumière proche-infrarouge et contenant ~ 500 millions d’objets célestes pour identifier environ 100 000 candidates naines brunes et étoiles de faible masse du voisinage solaire. À l'aide de l'outil BANYAN II, nous avons alors identifié quelques centaines d'objets appartenant fort probablement à une association jeune parmi cet échantillon et effectué un suivi spectroscopique en lumière proche-infrarouge pour les caractériser. Les travaux présentés ici ont mené à l'identification de 79 candidates naines brunes jeunes ainsi que 150 candidates étoiles de faible masse jeunes, puis un suivi spectroscopique nous a permis de confirmer le jeune âge de 49 de ces naines brunes et 62 de ces étoiles de faible masse. Nous avons ainsi approximativement doublé le nombre de naines brunes jeunes connues, ce qui a ouvert la porte à une caractérisation statistique de leur population. Ces nouvelles naines brunes jeunes représentent un laboratoire idéal pour mieux comprendre l'atmosphère des exoplanètes géantes gazeuses. Nous avons identifié les premiers signes d’une remontée dans la fonction de masse initiale des naines brunes aux très faibles masses dans l'association jeune Tucana-Horologium, ce qui pourrait indiquer que l’éjection d’exoplanètes joue un rôle important dans la composition de leur population. Les résultats du suivi spectroscopique nous ont permis de construire une séquence empirique complète pour les types spectraux M5-L5 à l'âge du champ, à faible (β) et très faible (γ) gravité de surface. Nous avons effectué une comparaison de ces données aux modèles d'évolution et d'atmosphère, puis nous avons construit un ensemble de séquences empiriques de couleur-magnitude et types spectraux-magnitude pour les naines brunes jeunes. Finalement, nous avons découvert deux nouvelles exoplanètes par un suivi en imagerie directe des étoiles jeunes de faible masse identifiées dans ce projet. La future mission GAIA et le suivi spectroscopique complet des candidates présentées dans cette thèse permettront de confirmer leur appartenance aux associations jeunes et de contraindre la fonction de masse initiale dans le régime sous-stellaire.

Exoplanet discoveries with the CoRoT space observatory

The CoRoT space observatory is a project which is led by the French space agency CNES and leading space research institutes in Austria, Brazil, Belgium, Germany and Spain and also the European Space Agency ESA. CoRoT observed since its launch in December 27, 2006 about 100 000 stars for the exoplanet channel, during 150 days uninterrupted high-precision photometry. Since the The CoRoT-team has several exoplanet candidates which are currently analyzed under its study, we report here the discoveries of nine exoplanets which were observed by CoRoT. Discovered exoplanets such as CoRoT-3b populate the brown dwarf desert and close the gap of measured physical properties between usual gas giants and very low mass stars. CoRoT discoveries extended the known range of planet masses down to about 4.8 Earth-masses (CoRoT-7b) and up to 21 Jupiter masses (CoRoT-3b), the radii to about 1.68 x 0.09 R (Earth) (CoRoT-7b) and up to the most inflated hot Jupiter with 1.49 x 0.09 R (Earth) found so far (CoRoT-1b), and the transiting exoplanet with the longest period of 95.274 days (CoRoT-9b). Giant exoplanets have been detected at low metallicity, rapidly rotating and active, spotted stars. Two CoRoT planets have host stars with the lowest content of heavy elements known to show a transit hinting towards a different planethost-star-metallicity relation then the one found by radial-velocity search programs. Finally the properties of the CoRoT-7b prove that rocky planets with a density close to Earth exist outside the Solar System. Finally the detection of the secondary transit of CoRoT-1b at a sensitivity level of 10(-5) and the very clear detection of the ""super-Earth"" CoRoT-7b at 3.5 x 10(-4) relative flux are promising evidence that the space observatory is being able to detect even smaller exoplanets with the size of the Earth.

Germanane: a Low Effective Mass and High Bandgap 2-D Channel Material for Future FETs

We investigate the electronic properties of Germanane and analyze its importance as 2-D channel material in switching devices. Considering two types of morphologies, namely, chair and boat, we study the real band structure, the effective mass variation, and the complex band structure of unstrained Germanane by density-functional theory. The chair morphology turns out to be a more effective channel material for switching devices than the boat morphology. Furthermore, we study the effect of elastic strain, van der Waals force, and vertical electric field on these band structure properties. Due to its very low effective mass with relatively high-energy bandgap, in comparison with the other 2-D materials, Germanane appears to provide superior performance in switching device applications.