CR-relatives Kähler manifolds

In this paper we show that two Kähler manifolds which do not share a Kähler submanifold, do not share either a Levi degenerate CR–submanifold with constant dimension Levi kernel. In particular, they do not share a CR–product. Further, we obtain that a Levi degenerate CR-submanifold of C^n cannot be isometrically immersed into a flag manifold

Non equilibrium optical properties in semiconductors from first--principles: a combined theoretical and experimental study of bulk silicon

The calculation of the equilibrium optical properties of bulk silicon by using the Bethe--Salpeter equation solved in the Kohn--Sham basis represents a cornerstone in the development of an ab--initio approach to the optical and electronic properties of materials. Nevertheless calculations of the {\em transient} optical spectrum using the same efficient and successful scheme are scarce. We report, here, a joint theoretical and experimental study of the transient reflectivity spectrum of bulk silicon. Femtosecond transient reflectivity is compared to a parameter--free calculation based on the non--equilibrium Bethe--Salpeter equation. By providing an accurate description of the experimental results we disclose the different phenomena that determine the transient optical response of a semiconductor. We give a parameter--free interpretation of concepts like bleaching, photo--induced absorption and stimulated emission, beyond the Fermi golden rule. We also introduce the concept of optical gap renormalization, as a generalization of the known mechanism of band gap renormalization. The present scheme successfully describes the case of bulk silicon, showing its universality and accuracy.Comment: 14 pages, 13 figure

Gradient estimates under integral Ricci bounds

In this paper we study $W^{1,p}$ global regularity estimates for solutions of $\Delta u = f$ on Riemannian manifolds. Under integral (lower) bounds on the Ricci tensor we prove the validity of $L^p$-gradient estimates of the form $|| \nabla u ||_{L^p} \le C (|| u ||_{L^p} + || \Delta u||_{L^p})$. We also construct a counterexample which proves that the previously known constant lower bounds on the Ricci curvature are optimal in the pointwise sense. The relation between $L^p$-gradient estimates and different notions of Sobolev spaces is also investigated.Comment: 9 pages, comments are welcome

Optical simulation of neutrino oscillations in binary waveguide arrays

We theoretically propose and investigate an optical analogue of neutrino oscillations in a pair of vertically displaced binary waveguide arrays with longitudinally modulated effective refractive index. Optical propagation is modeled through coupled-mode equations, which in the continuous limit converge to two coupled Dirac equations for fermionic particles with different mass states, analogously to neutrinos. In addition to simulating neutrino oscillation in the noninteracting regime, our optical setting enables us to explore neutrino interactions in extreme regimes that are expected to play an important role in massive supernova stars. In particular, we predict the quenching of neutrino oscillations and the existence of topological defects, i.e., neutrino solitons, which in our photonic simulator should be observable as excitation of optical gap solitons propagating along the binary arrays at high excitation intensities

Birth registration and child undernutrition in sub-saharan Africa

Objective: In many countries of the world millions of people are not registered at birth. However, in order to assess children’s nutritional status it is necessary to have an exact knowledge of their age. In the present paper we discuss the effects of insufficient or imprecise age data on estimates of undernutrition prevalence. Design: Birth registration rates and levels of stunting, underweight and wasting were retrieved from Multiple Indicator Cluster Surveys and Demographic and Health Surveys of thirty-seven sub-Saharan African countries, considering the subdivision in wealth quintiles. The composition of the cross-sectional sample used for nutritional evaluation was analysed using a permutation test. Logistic regression was applied to analyse the relationship between birth registration and undernutrition. The 95 % probability intervals and Student’s t test were used to evaluate the effect of age bias and error. Results: Heterogeneous sampling designs were detected among countries, with different percentages of children selected for anthropometry. Further, registered children were slightly more represented within samples used for nutritional analysis than in the total sample. A negative relationship between birth registration and undernutrition was recognized, with registered children showing a better nutritional status than unregistered ones, even within each wealth quintile. The over- or underestimation of undernutrition in the case of systematic over- or underestimation of age, respectively, the latter being more probable, was quantified up to 28 %. Age imprecision was shown to slightly overestimate undernutrition. Conclusions: Selection bias towards registered children and underestimation of children’s age can lead to an underestimation of the prevalence of undernutrition

embolization of iliac metastasis during lenvatinib treatment in patient with advanced hurthle cell thyroid carcinoma

Lenvatinib is a tyrosine kinase inhibitor (TKI) with antiproliferative and antiangiogenic effects indicated for the treatment of progressive, locally advanced or metastatic progressive thyroid carcinoma, refractory to radioactive iodine therapy. Antiangiogenic therapies induce ischemic necrosis of tumor tissue, with increased risk of hemorrhagic complications. The management of hemorrhagic risk is based on precautionary measures and for any surgical procedure, it is advised to interrupt the treatment in order to avoid complications. 'Flare-up' of tumor activity may follow TKI interruption. However, it is not known if continuing TKIs during minimally invasive interventions is safe. We report here the first case in which an embolization of metastasis is performed without interrupting lenvatinib treatment. The procedure was successful and free of complications

Embolization of iliac metastasis during lenvatinib treatment in patient with advanced Hürthle cell thyroid carcinoma

Lenvatinib is a tyrosine kinase inhibitor (TKI) with antiproliferative and antiangiogenic effects indicated for the treatment of progressive, locally advanced or metastatic progressive thyroid carcinoma, refractory to radioactive iodine therapy. Antiangiogenic therapies induce ischemic necrosis of tumor tissue, with increased risk of hemorrhagic complications. The management of hemorrhagic risk is based on precautionary measures and for any surgical procedure, it is advised to interrupt the treatment in order to avoid complications. 'Flare-up' of tumor activity may follow TKI interruption. However, it is not known if continuing TKIs during minimally invasive interventions is safe. We report here the first case in which an embolization of metastasis is performed without interrupting lenvatinib treatment. The procedure was successful and free of complications

Patterns of Hand Variation – New Data on a Sardinian Sample

This study is an analysis of the patterns of variation of the human hand, particularly the metric characters of palm, fingers and distal phalanges. Anthropometric measurements were performed on 146 Sardinian men and women, aged 21 to 31 years. The data were analyzed by inferential statistics (paired Student’s t test, analysis of variance), and Principal Components Analysis. The results indicate that size factors are the principal source of variation. A residual adimensional component of variability is related to diversification between the fingers as a whole and the distal phalanges, and between the thumb and the other fingers. Sexual dimorphism is evident. Men present greater dimensions and greater relative length of the thumb with respect to the other fingers than women

Effect of influenza-induced fever on human bioimpedance values

BACKGROUND AND AIMS: Bioelectrical impedance analysis (BIA) is a widely used technique to assess body composition and nutritional status. While bioelectrical values are affected by diverse variables, there has been little research on validation of BIA in acute illness, especially to understand prognostic significance. Here we report the use of BIA in acute febrile states induced by influenza. METHODS: Bioimpedance studies were conducted during an H1N1 influenza A outbreak in Venezuelan Amerindian villages from the Amazonas. Measurements were performed on 52 subjects between 1 and 40 years of age, and 7 children were re-examined after starting Oseltamivir treatment. Bioelectrical Impedance Vector Analysis (BIVA) and permutation tests were applied. RESULTS: For the entire sample, febrile individuals showed a tendency toward greater reactance (p=0.058) and phase angle (p=0.037) than afebrile individuals, while resistance and impedance were similar in the two groups. Individuals with repeated measurements showed significant differences in bioimpedance values associated with fever, including increased reactance (p<0.001) and phase angle (p=0.007), and decreased resistance (p=0.007) and impedance (p<0.001). CONCLUSIONS: There are bioelectrical variations induced by influenza that can be related to dehydration, with lower extracellular to intracellular water ratio in febrile individuals, or a direct thermal effect. Caution is recommended when interpreting bioimpedance results in febrile states