Photonic band gaps analysis of Thue-Morse multilayers made of porous silicon

Dielectric aperiodic Thue-Morse structures up to 128 layers have been fabricated by using porous silicon technology. The photonic band gap properties of Thue-Morse multilayers have been theoretically investigated by means of the transfer matrix method and the integrated density of states. The theoretical approach has been compared and discussed with the reflectivity measurements at variable angles for both the transverse electric and transverse magnetic polarizations of light. The photonic band gap regions, wide 70 nm and 90 nm, included between 0 and 30°, have been observed for the sixth and seventh orders, respectively

KDSource: desarrollo de una herramienta computacional para calculo de blindajes

El presente proyecto consistió en el desarrollo de una herramienta computacional de modelado de fuentes distribucionales, denominada KDSource. La misma se orienta principalmente a aplicaciones en cálculos de blindajes y/o haces de partículas, y permite la comunicación con varios códigos Monte Carlo, con particular enfoque en McStas y TRIPOLI. Se desarrolló un paquete de herramientas para el modelado general de fuentes de partículas por el método Kernel Density Estimation, método superador de la técnica de histogramas empleada anteriormente. Dichas fuentes se basan en listas de tracks capturadas en simulaciones Monte Carlo, y permiten la generación ilimitada de nuevas partículas respetando la distribución estimada, sin repeticiones. El paquete se compone de una librería en Python, a través de la cual se realiza el análisis y optimización de la fuente, y una librería en C, mediante la cual se generan nuevas partículas. Además cuenta con una aplicación de línea de comando y un conjunto de archivos auxiliares que facilitan la utilización de las fuentes. Los principales beneficios de la herramienta, en simulaciones Monte Carlo, son la reducción de varianza y el acople entre códigos. Se demostró el funcionamiento y la utilidad de la herramienta en un cálculo de blindajes sobre un diseño conceptual de guía neutrónica, basado en el haz GF1 del reactor RA10. El cálculo incluyó un acople entre óptica y transporte de radiación, y permitió obtener mapas de dosis por neutrones, fotones prompt, fotones de fuente y fotones de activación en posiciones lejanas al núcleo

Evolution of the electronic structure across the filling-control and bandwidth-control metal-insulator transitions in pyrochlore-type Ru oxides

We have performed photoemission and soft x-ray absorption studies of pyrochlore-type Ru oxides, namely, the filling-control system Sm$_{2-x}$Ca$_x$Ru$_2$O$_7$ and the bandwidth-control system Sm$_{2-x}$Bi$_x$Ru$_2$O$_7$, which show insulator-to-metal transition with increasing Ca and Bi concentration, respectively. Core levels and the O 2$p$ valence band in Sm$_{2-x}$Ca$_x$Ru$_2$O$_7$ show almost the same amount of monotonous upward energy shifts with Ca concentration, which indicates that the chemical potential is shifted downward due to hole doping. The Ru 4$d$ band in Sm$_{2-x}$Ca$_x$Ru$_2$O$_7$ is also shifted toward the Fermi level ($E_F$) with hole doping and the density of states (DOS) at $E_F$ increases. The core levels in Sm$_{2-x}$Bi$_x$Ru$_2$O$_7$, on the other hand, do not show clear energy shifts except for the Ru 3$d$ core level, whose line shape change also reflects the increase of metallic screening with Bi concentration. We observe pronounced spectral weight transfer from the incoherent to the coherent parts of the Ru 4d $t_{2g}$ band with Bi concentration, which is expected for a bandwidth-control Mott-Hubbard system. The increase of the DOS at $E_F$ is more abrupt in the bandwidth-control Sm$_{2-x}$Bi$_x$Ru$_2$O$_7$ than in the filling-control Sm$_{2-x}$Ca$_x$Ru$_2$O$_7$, in accordance with a recent theoretical prediction. Effects of charge transfer between the Bi 6$sp$ band and the Ru 4$d$ band are also discussed.Comment: 11 pages, 6 figure

Current driven rotating kink mode in a plasma column with a non-line-tied free end

First experimental measurements are presented for the kink instability in a linear plasma column which is insulated from an axial boundary by finite sheath resistivity. Instability threshold below the classical Kruskal-Shafranov threshold, axially asymmetric mode structure and rotation are observed. These are accurately reproduced by a recent kink theory, which includes axial plasma flow and one end of the plasma column that is free to move due to a non-line-tied boundary condition.Comment: 4 pages, 6 figure

Six Sigma Approach for a First Evaluation of a Pharmacological Therapy in Tongue Cancer

Tongue cancers are among the most frequent malignancies in the population and their influence can be affected by many risk factors. Patients undergoing tongue surgery face different complications and can experience a long length of hospital stay (LOS). The aim of this paper is to compare two pharmacological therapies in order to understand which one decreases the LOS. At the University hospital of Naples “Federico II” two antibiotics were employed: Cefazolin plus Clindamycin and Ceftriaxone. Six Sigma methodology was employed to analyse two group of patients treated with these two different antibiotics: 55 patients treated with the antibiotic Cefazolin plus Clindamycin and 66 patients with the antibiotic Ceftriaxone. This is the first time that this methodology is used in order to compare two antibiotics in the oncology field. The results obtained show clearly and with a statistical evidence that patients treated with Ceftriaxone experienced a lower LOS (−28.6% in terms of percentage between medians). Reducing the LOS for patients means limiting the number of complications and, therefore, reducing the hospitalization costs. It would be valuable for both hospital and patients: the former would save money that they could invest in other important care activities; the latter would experience a higher quality of care with fewer complications

Expression of Werner and Bloom syndrome genes is differentially regulated by in vitro HIV-1 infection of peripheral blood mononuclear cells

In HIV infection, continuous immune activation leads to accelerated ageing of the adaptive immune system, similar to that observed in elderly people. We investigated the expression of WRN and BLM (genes involved in disorders characterized by premature ageing, genomic instability and cancer predisposition) in peripheral blood mononuclear cells (PBMC) activated in vitro with phytohaemagglutinin (PHA) and infected with different HIV-1 strains. The steady state levels of mRNA were analysed by reverse transcription-polymerase chain reaction (RT-PCR), and protein expression was assayed using immunocytochemistry and Western blot techniques. In uninfected PBMC, PHA stimulation induced an increase in BLM mRNA and protein expression, while WRN expression remained virtually unchanged. When PBMC were infected in vitro with a lymphotropic HIV-1 strain, the level of BLM mRNA showed a peak at 24 h of infection, followed by a decline to uninfected culture levels. A similar result failed to be seen using an R5-tropic HIV-1 strain. In accordance with mRNA expression, in HIV-infected cultures PBMC were stained more frequently and more intensely by a BLM-specific antibody as compared to uninfected cultures, staining peaking at 24. Conversely, WRN expression was not modulated by HIV-1. The proportion of cells showing BLM up-regulation, established by immunocytochemical staining, was much greater than the proportion of productively infected PBMC, as established by proviral DNA measurement. This result indicates that BLM up-regulation is probably a result of an indirect bystander cell effect. Activation of the BLM gene in infected PBMC suggests that premature ageing could be a further immunopathogenetic mechanism involved in HIV-induced immunodeficiency, and points to a possible new candidate target for innovative therapeutic intervention

Structural and functional characterization of (110)-oriented epitaxial La2/3Ca1/3MnO3 electrodes and SrTiO3 tunnel barriers

La2/3Ca1/3MnO3 (LCMO) films have been deposited on (110)-oriented SrTiO3 (STO) substrates. X-ray diffraction and high-resolution electron microscopy reveal that the (110) LCMO films are epitaxial and anisotropically in-plane strained, with higher relaxation along the [1¿10] direction than along the [001] direction; x-ray absorption spectroscopy data signaled the existence of a single intermediate Mn3+/4+ 3d-state at the film surface. Their magnetic properties are compared to those of (001) LCMO films grown simultaneously on (001) STO substrates It is found that (110) LCMO films present a higher Curie temperature (TC) and a weaker decay of magnetization when approaching TC than their (001) LCMO counterparts. These improved films have been subsequently covered by nanometric STO layers. Conducting atomic-force experiments have shown that STO layers, as thin as 0.8 nm, grown on top of the (110) LCMO electrode, display good insulating properties. We will show that the electric conductance across (110) STO layers, exponentially depending on the barrier thickness, is tunnel-like. The barrier height in STO (110) is found to be similar to that of STO (001). These results show that the (110) LCMO electrodes can be better electrodes than (001) LCMO for magnetic tunnel junctions, and that (110) STO are suitable insulating barriers

Alterations in the Interleukin-1/Interleukin-1 Receptor Antagonist Balance Modulate Cardiac Remodeling following Myocardial Infarction in the Mouse

Background Healing after acute myocardial infarction (AMI) is characterized by an intense inflammatory response and increased Interleukin-1 (IL-1) tissue activity. Genetically engineered mice lacking the IL-1 receptor (IL-1R1-/-, not responsive to IL-1) or the IL-1 receptor antagonist (IL-1Ra, enhanced response to IL-1) have an altered IL-1/IL-1Ra balance that we hypothesize modulates infarct healing and cardiac remodeling after AMI. Methods IL-1R1-/- and IL-1Ra-/- male mice and their correspondent wild-types (WT) were subjected to permanent coronary artery ligation or sham surgery. Infarct size (trichrome scar size), apoptotic cell death (TUNEL) and left ventricular (LV) dimensions and function (echocardiography) were measured prior to and 7 days after surgery. Results When compared with the corresponding WT, IL-1R1-/- mice had significantly smaller infarcts (−25%), less cardiomyocyte apoptosis (−50%), and reduced LV enlargement (LV end-diastolic diameter increase [LVEDD], −20%) and dysfunction (LV ejection fraction [LVEF] decrease, −50%), whereas IL-1Ra-/- mice had significantly larger infarcts (+75%), more apoptosis (5-fold increase), and more severe LV enlargement (LVEDD increase,+30%) and dysfunction (LVEF decrease, +70%)(all P values \u3c0.05). Conclusions An imbalance in IL-1/IL-1Ra signaling at the IL-1R1 level modulates the severity of cardiac remodeling after AMI in the mouse, with reduced IL-1R1 signaling providing protection and unopposed IL-1R1 signaling providing harm