709 research outputs found

    Prenatal diagnosis of facial clefts: evaluation of a specialised counselling.

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    Prenatal diagnosis of cleft lip and palate has raised many questions concerning the best way to inform the parents and offer appropriate support during the remaining pregnancy to help prepare a positive birth experience. Prenatal counselling differs according to who is responsible, and to that person's knowledge of the practical aspects of care and the impact of the malformation on the child's quality of life. The aim of the study was to evaluate our current techniques and modify them when appropriate. 29 couples having experienced prenatal diagnosis were asked to respond retrospectively to a questionnaire. Personal obstetric and family history, timing and quality of information provided and their impressions at birth were considered. The parents used several sources of information: the obstetrician, the counsel by the cleft team surgeon, the parents support groups and the Internet. 93% of the parents felt well prepared psychologically for the birth of their child and concerning the practical aspects of care. 54% felt relieved that their child was less affected than imagined. 96% considered prenatal diagnosis a benefit. Basic information should be provided soon after ultrasound confirmation, followed by progressively more detailed technical discussions over the remaining pregnancy

    Intersubband transitions in nonpolar GaN/Al(Ga)N heterostructures in the short and mid-wavelength infrared regions

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    This paper assesses nonpolar m- and a-plane GaN/Al(Ga)N multi-quantum-wells grown on bulk GaN for intersubband optoelectronics in the short- and mid-wavelength infrared ranges. The characterization results are compared to those for reference samples grown on the polar c-plane, and are verified by self-consistent Schr\"odinger-Poisson calculations. The best results in terms of mosaicity, surface roughness, photoluminescence linewidth and intensity, as well as intersubband absorption are obtained from m-plane structures, which display room-temperature intersubband absorption in the range from 1.5 to 2.9 um. Based on these results, a series of m-plane GaN/AlGaN multi-quantum-wells were designed to determine the accessible spectral range in the mid-infrared. These samples exhibit tunable room-temperature intersubband absorption from 4.0 to 5.8 um, the long-wavelength limit being set by the absorption associated with the second order of the Reststrahlen band in the GaN substrates

    An Extension of the Fluctuation Theorem

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    Heat fluctuations are studied in a dissipative system with both mechanical and stochastic components for a simple model: a Brownian particle dragged through water by a moving potential. An extended stationary state fluctuation theorem is derived. For infinite time, this reduces to the conventional fluctuation theorem only for small fluctuations; for large fluctuations, it gives a much larger ratio of the probabilities of the particle to absorb rather than supply heat. This persists for finite times and should be observable in experiments similar to a recent one of Wang et al.Comment: 12 pages, 1 eps figure in color (though intelligible in black and white

    Historical flash floods retromodelling in the Ondara River in Tàrrega (NE Iberian Peninsula)

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    Flash floods in the Ondara River have caused many fatalities and damages in the town of Tàrrega in the last 400 yr. Unfortunately, no flow records are available. <br><br> However, floods can sometimes be reconstructed thanks to available historical information: limnimarks, written accounts and archaeological surveys. Indeed, from these data and using the retromodelling method on three different scenarios to take into account morphology changes, the peak flows of the seven greatest floods occurred in Tàrrega since the 17th century were estimated. <br><br> The results showed that the heaviest flood's specific peak flow (10.7 m<sup>3</sup> s<sup>−1</sup> km<sup>−2</sup>) ranks among the highest ever modelled or measured in similar-sized catchments in the Western Mediterranean region. The results pointed out, as well, that the changes in channel's morphology (mainly, the disappearance of a mediaeval bridge under sediment) caused by one of the floods increased the hydraulic capacity of a crucial cross-section. All this resulted in modest floods invading the town less often, but with much faster and, thus, more destructive flows. <br><br> A preliminary estimation of the results' uncertainty was 4% for great floods and 18% for modest floods. <br><br> The reconstructed peak flows will be introduced in a database for a future use in climatic and hydrological studies

    Phimosis et corticostéroïdes topiques : une alternative au traitement chirurgical? : revue Cochrane pour le praticien

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    Question clinique: Une mère vous consulte avec son fils âgé de 6 ans, en bonne santé habituelle mais connu pour un phimosis. Il ne présente pas de troubles mictionnels, ni d'antécédents de balanite ou de paraphimosis. Sa mère est inquiète de voir le phimosis persister et vous demande s'il existe une alternative au traitement chirurgical. Contexte: Présent dès la naissance, le phimosis physiologique se résout spontanément dans la majorité des cas. Alors que 10% des garçons présentent un phimosis à l'âge de 3 ans, cette prévalence diminue à 6-8% à l'âge de 7 ans, pour atteindre 1% à l'âge de 16 ans. On parle de phimosis pathologique lorsque le prépuce présente des cicatrices fibreuses suite à des inflammations répétées ou des décalottages forcés. Cependant, la distinction clinique entre un phimosis pathologique et physiologique est difficile et le traitement chirurgical reste fréquent. Un traitement par corticostéroïdes topiques est utilisé depuis de nombreuses années pour son action anti-inflammatoire et immunosuppressive (diminution de la production de collagène). Pourtant, il n'existe pas de preuve quant à l'efficacité et la sécurité de ce traitement

    A new improved optimization of perturbation theory: applications to the oscillator energy levels and Bose-Einstein critical temperature

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    Improving perturbation theory via a variational optimization has generally produced in higher orders an embarrassingly large set of solutions, most of them unphysical (complex). We introduce an extension of the optimized perturbation method which leads to a drastic reduction of the number of acceptable solutions. The properties of this new method are studied and it is then applied to the calculation of relevant quantities in different ϕ4\phi^4 models, such as the anharmonic oscillator energy levels and the critical Bose-Einstein Condensation temperature shift ΔTc\Delta T_c recently investigated by various authors. Our present estimates of ΔTc\Delta T_c, incorporating the most recently available six and seven loop perturbative information, are in excellent agreement with all the available lattice numerical simulations. This represents a very substantial improvement over previous treatments.Comment: 9 pages, no figures. v2: minor wording changes in title/abstract, to appear in Phys.Rev.

    Signatures of two-dimensionalisation of 3D turbulence in presence of rotation

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    A reason has been given for the inverse energy cascade in the two-dimensionalised rapidly rotating 3D incompressible turbulence. For such system, literature shows a possibility of the exponent of wavenumber in the energy spectrum's relation to lie between -2 and -3. We argue the existence of a more strict range of -2 to -7/3 for the exponent in the case of rapidly rotating turbulence which is in accordance with the recent experiments. Also, a rigorous derivation for the two point third order structure function has been provided helping one to argue that even with slow rotation one gets, though dominated, a spectrum with the exponent -2.87, thereby hinting at the initiation of the two-dimensionalisation effect with rotation.Comment: An extended and typos-corrected version of the earlier submissio

    Transport Properties of a Chain of Anharmonic Oscillators with random flip of velocities

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    We consider the stationary states of a chain of nn anharmonic coupled oscillators, whose deterministic hamiltonian dynamics is perturbed by random independent sign change of the velocities (a random mechanism that conserve energy). The extremities are coupled to thermostats at different temperature TT_\ell and TrT_r and subject to constant forces τ\tau_\ell and τr\tau_r. If the forces differ ττr\tau_\ell \neq \tau_r the center of mass of the system will move of a speed VsV_s inducing a tension gradient inside the system. Our aim is to see the influence of the tension gradient on the thermal conductivity. We investigate the entropy production properties of the stationary states, and we prove the existence of the Onsager matrix defined by Green-kubo formulas (linear response). We also prove some explicit bounds on the thermal conductivity, depending on the temperature.Comment: Published version: J Stat Phys (2011) 145:1224-1255 DOI 10.1007/s10955-011-0385-
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