Observational Constraints on Silent Quartessence

We derive new constraints set by SNIa experiments (`gold' data sample of Riess et al.), X-ray galaxy cluster data (Allen et al. Chandra measurements of the X-ray gas mass fraction in 26 clusters), large scale structure (Sloan Digital Sky Survey spectrum) and cosmic microwave background (WMAP) on the quartessence Chaplygin model. We consider both adiabatic perturbations and intrinsic non-adiabatic perturbations such that the effective sound speed vanishes (Silent Chaplygin). We show that for the adiabatic case, only models with equation of state parameter $|\alpha |\lesssim 10^{-2}$ are allowed: this means that the allowed models are very close to \LambdaCDM. In the Silent case, however, the results are consistent with observations in a much broader range, -0.3<\alpha<0.7.Comment: 7 pages, 12 figures, to be submitted to JCA

Porous bioactive composites from marine origin based in chitosan and hydroxylapatite particles

An optimal carrier for bone tissue engineering should be both a controlled release system and a scaffold. In the former role, the carrier must prevent rapid factor clearance and ideally meter out the growth factor in a predictable manner, allowing therapeutic doses to stimulate target cells for the appropriate duration. In the latter role, the material should act as a permissive environment into which bone cells would be attracted to migrate and begin the process of depositing bone matrix. Therefore the direct incorporation of growth factor in porous scaffolds should be a desirable goal. The inclusion of a bioactive ceramic on the scaffold design will confer to the systems a bone bonding behaviour that will guide bone formation. This work reports the development of composite chitosan/HA (from algal origin) porous structures produced by means of freeze-drying processing routes that can be further loaded with a biologically active agent. The developed bioactive 3D structures (completely from marine origin) have potential application as tissue engineering scaffolds and drug delivery systems due to their morphological and bioactive properties.(undefined

Tratamiento de reflujo vesicoureteral

Abstract OBJECTIVES: Vesicoureteral reflux (VUR) is a frequent pathology, with an incidence of 29/50% in children studied for urinary tract infection (UTI) and 20% of newborns with the diagnosis of prenatal hydronephrosis. Over the years, the treatment has been the subject of many meetings, many research studies, and continues being a topic under discussion. The number of candidates for surgical treatment increased with the development of minimally invasive endoscopic techniques by subureteral injection of bulking agents. We present the results of the surgical treatment of VUR between 2001 and 2006. METHODS: We performed a retrospective study of the endoscopic treatment of VUR by subureteral injection of Dextranomer and hyaluronic acid copolymer (Copol-Dx/AH). All children undergoing treatment between July 1st 2001 and December 30th 2006 were included in this study. Treatment was performed in children with VUR grade II or greater. All patients presenting no reflux or grade I VUR on control VCUG were considered cured; stopping antibiotic prophylaxis was proposed in these cases. RESULTS: 661 children underwent treatment, 607 endoscopic and 54 with the Cohen technique. Among children treated endoscopically, 437 where females and 170 males. VUR was bilateral in 37.7% of the cases, with grade II being the most frequent (40% in males and 57% in females). Overall success rate was 70% after first treatment, 75% after second treatment and increased to 78% after the third. CONCLUSIONS: Subureteral injection of dextranomer and hyaluronic acid copolymer is on effective treatment in children with VUR, independently of the grade. It is a simple, safe, well tolerated procedure with low associated morbidity. Currently, it is the surgical treatment of choice in most patients with VUR

Universal velocity distributions in an experimental granular fluid

We present experimental results on the velocity statistics of a uniformly heated granular fluid, in a quasi-2D configuration. We find the base state, as measured by the single particle velocity distribution $f(c)$, to be universal over a wide range of filling fractions and only weakly dependent on all other system parameters. There is a consistent overpopulation in the distribution's tails, which scale as $f\propto\exp(\mathrm{const.}\times c^{-3/2})$. More importantly, the high probability central region of $f(c)$, at low velocities, deviates from a Maxwell-Boltzmann by a second order Sonine polynomial with a single adjustable parameter, in agreement with recent theoretical analysis of inelastic hard spheres driven by a stochastic thermostat. To our knowledge, this is the first time that Sonine deviations have been measured in an experimental system.Comment: 13 pages, 15 figures, with minor corrections, submitted to Phys. Rev.

Impactos do fenômeno ENOS sobre a temperatura no Brasil.

Neste trabalho, a variabilidade das temperaturas máximas e mínimas mensais de 265 estações convencionais, componentes do Banco de Dados Meteorológicos para Ensino e Pesquisa (BDMEP do INMET), nos últimos 50 anos, foi relacionada com as variações do Oceanic Niño Index do NOAA Climate Prediction Center através do treinamento de uma rede neural artificial. Os resultados da pesquisa mostram a relação quase que direta entre ENOS (El Niño-Oscilação Sul) e as temperaturas máximas e mínimas mensais no Brasil. Foram escolhidas algumas localidades para demonstrar os resultados da pesquisa: Manaus, Recife, Cuiabá, Brasília, São Paulo e Porto Alegre. Os eventos de El Niño contribuem para o aumento das temperaturas máximas e mínimas enquanto o inverso ocorre em eventos de La Niña, exceto para a região Amazônica. Em anos de La Niña ocorrem diminuição das temperaturas do ar em quase todas as regiões do Brasil. O impacto do fenômeno ENOS no país se faz mais presente nos meses de inverno e primavera.bitstream/item/76849/1/Impactos-fenomeno.pd

Bilayered chitosan-based scaffolds for osteochondral tissue engineering : influence of hydroxyapatite on in vitro cytotoxicity and dynamic bioactivity studies in a specific double-chamber bioreactor

Osteochondral tissue engineering presents a current research challenge due to the necessity of combining both bone and cartilage tissue engineering principles. In the present study, bilayered chitosan-based scaffolds are developed based on the optimization of both polymeric and composite scaffolds. A particle aggregation methodology is proposed in order to achieve an improved integrative bone–cartilage interface needed for this application, since any discontinuity is likely to cause long-term device failure. Cytotoxicity was evaluated by the MTS assay with the L929 fibroblast cell line for different conditions. Surprisingly, in composite scaffolds using unsintered hydroxyapatite, cytotoxicity was observed in vitro. This work reports the investigation that was conducted to overcome and explain this behaviour. It is suggest that the uptake of divalent cations may induce the cytotoxic behaviour. Sintered hydroxyapatite was consequently used and showed no cytotoxicity when compared to the controls. Microcomputed tomography (micro-CT) was carried out to accurately quantify porosity, interconnectivity, ceramic content, particle and pore sizes. The results showed that the developed scaffolds are highly interconnected and present the ideal pore size range to be morphometrically suitable for the proposed applications. Dynamical mechanical analysis (DMA) demonstrated that the scaffolds are mechanically stable in the wet state even under dynamic compression. The obtained elastic modulus was, respectively, 4.21 ± 1.04, 7.98 ± 1.77 and 6.26 ± 1.04 MPa at 1 Hz frequency for polymeric, composite and bilayered scaffolds. Bioactivity studies using both a simulated body fluid (SBF) and a simulated synovial fluid (SSF) were conducted in order to assure that the polymeric component for chondrogenic part would not mineralize, as confirmed by scanning electron microscopy (SEM), inductively coupled plasma-optical emission spectroscopy (ICP) and energy-dispersive spectroscopy (EDS) for different immersion periods. The assays were carried out also under dynamic conditions using, for this purpose, a specifically designed double-chamber bioreactor, aiming at a future osteochondral application. It was concluded that chitosan-based bilayered scaffolds produced by particle aggregation overcome any risk of delamination of both polymeric and composite parts designed, respectively, for chondrogenic and osteogenic components that are mechanically stable. Moreover, the proposed bilayered scaffolds could serve as alternative, biocompatible and safe biodegradable scaffolds for osteochondral tissue engineering applications

Optimization of chitosan-based composite and bi-layered scaffolds produced by particles aggregation for osteochondral tissue engineering: Influence of hydroxylapatite

[Excerpt] Osteochondral tissue engineering presents a challenge to the present research due to requirements’ combination of both bone and cartilage tissue engineering. In the present study, bilayered chitosan scaffolds are proposed based in the optimization of polymeric and composite scaffolds. µ-CT was carried out for accurate morphometric characterization quantifying porosity, interconnectivity, ceramic content, particles and pores size. The results showed that the developed scaffolds are highly interconnected and present ideal pore size range, being morphometrically adequate for the proposed applications. [...]info:eu-repo/semantics/publishedVersio

Caging dynamics in a granular fluid

We report an experimental investigation of the caging motion in a uniformly heated granular fluid, for a wide range of filling fractions, $\phi$. At low $\phi$ the classic diffusive behavior of a fluid is observed. However, as $\phi$ is increased, temporary cages develop and particles become increasingly trapped by their neighbors. We statistically analyze particle trajectories and observe a number of robust features typically associated with dense molecular liquids and colloids. Even though our monodisperse and quasi-2D system is known to not exhibit a glass transition, we still observe many of the precursors usually associated with glassy dynamics. We speculate that this is due to a process of structural arrest provided, in our case, by the presence of crystallization.Comment: 4 pages, 5 figures, submitted to Phys. Rev. Let