Diferenciação de Fluxos Sem Manutenção de Estados em Roteadores

O tráfego da Internet é dominado por transações de curta duração. Todavia, apesar da grande quantidade, os fluxos curtos são responsáveis por uma pequena porção da carga total dos enlaces e ainda disputam, injustamente, recursos com conexões que transportam grandes volumes de dados. O desempenho de sessões TCP (Transmission Control Protocol) operando em fase de slow-start ou em regime de pequenas janelas sofre de forma significativa ao com- partilhar buffers e capacidade dos enlaces com grandes rajadas oriundas de sessões na fase de controle de congestionamento. Uma forma de amenizar essa desigualdade é tratar diferencia- damente fluxos curtos e longos. Neste trabalho estudamos, desenvolvemos e implementamos técnicas sem manutenção de estados (stateless) de forma a atingirmos um bom compromisso entre eficiência e complexidade na diferenciação de serviço entre fluxos curtos e longos. Do ponto de vista metodológico, optamos pela implementação experimental sobre roteadores fí- sicos e utilizando tráfego real. Esta escolha trouxe maior confiabilidade aos resultados, uma vez que eles não ficaram atrelados à qualidade dos modelos de simuladores, os quais são fre- quentemente simplórios demais para corresponder ao real comportamento de uma rede. Para a implementação de roteadores que viabilizassem a alteração dos esquemas de tratamento de pacotes utilizou-se a plataforma Click. Em relação à metodologia de testes, propomos um ambi- ente controlado que possibilita comparações entre diferentes técnicas sob tráfego real, oriundo de um backup de um hard-disk via FTP (File Transfer Protocol). Dentre as técnicas de diferen- ciação de fluxos, apresentamos, no conhecimento dos autores, a primeira implementação física de um roteador com o mecanismo RuN2C (Running Number 2 Class). Trazemos ainda a con- tribuição da investigação de seu desempenho quando diferentes técnicas de escalonamento são aplicadas. Propomos ainda um novo método de diferenciação de fluxos, denominado RAFLE (Random Assorter of Flow LEngths), que não exige nenhuma alteração de protocolos hoje exis- tentes, o que facilitaria sua implantação em ambiente em operação. A classificação de pacotes pertencentes a fluxos longos e curtos é inferida a partir de uma pequena tabela com as informa- ções de identificação dos últimos pacotes encaminhados, não sendo necessário manter estados dos fluxos ativos. Como resultados relevantes podemos destacar que o desempenho do RAFLE supera o RUN2C e aproxima-se bastante do desempenho da diferenciação com conhecimento completo dos fluxos (full-state) em diferentes cenários de tráfego

Electron-phonon interaction in the solid form of the smallest fullerene C20_{20}

The electron-phonon coupling of a theoretically devised carbon phase made by assembling the smallest fullerenes C$_{20}$ is calculated from first principles. The structure consists of C$_{20}$ cages in an {\it fcc} lattice interlinked by two bridging carbon atoms in the interstitial tetrahedral sites ({\it fcc}-C$_{22}$). The crystal is insulating but can be made metallic by doping with interstitial alkali atoms. In the compound NaC$_{22}$ the calculated coupling constant $\lambda/N(0)$ is 0.28 eV, a value much larger than in C$_{60}$, as expected from the larger curvature of C$_{20}$. On the basis of the McMillan's formula, the calculated $\lambda$=1.12 and a $\mu^*$ assumed in the range 0.3-0.1 a superconducting T$_c$ in the range 15-55 K is predicted.Comment: 7 page

Association of Body Mass Index of HIV-1-Infected Pregnant Women and Infant Weight, Body Mass Index, Length, and Head Circumference: The NISDI Perinatal Study.

This study assessed the relationship between the body mass index (BMI) of HIV-1-infected women and their infants' perinatal outcomes. The study population consisted of women enrolled in the NICHD International Site Development Initiative (NISDI) Perinatal Study with data allowing calculation of the BMI adjusted for length of gestation (adjBMI), who delivered singleton infants. Outcome variables included infant growth parameters at birth (weight, BMI, length and head circumference) and gestational age. Of 697 women from Argentina, the Bahamas, Brazil and Mexico who were included in the analysis, the adjBMI was classified as underweight for 109 (15.6%), normal for 418 (60.0%), overweight for 88 (12.6%) and obese for 82 (11.8%). Median infant birth weight, BMI, birth length and head circumference differed significantly according to maternal adjBMI (P</=0.0002). Underweight mothers gave birth to infants with lower weight, lower BMI, shorter length and smaller head circumference, while infants born to normal, overweight and obese mothers were of similar size

EVALUATION OF THE CYTOTOXICITY OF PULP FLOOR PERFORATION FILLING MATERIALS BY USING IN PARALLEL 2D AND 3D CULTURE MODELS

Oral Communication presented at the ";Forum des Jeunes Chercheurs";, Brest (France) 2011

Influence of bulla volume on postbullectomy outcome

Objective: To quantify the contribution of the resected volume and the presence of associated, functionally significant emphysema to the postoperative improvement of pulmonary function after resection of giant lung bullae. Design: Patients undergoing elective surgery for giant bullae who had complete pulmonary function and radiographic studies performed were reviewed retrospectively. Setting: All 25 patients underwent surgery at the thoracic surgery unit of the University of Pisa, Pisa, Italy. Methods: Pulmonary function was assessed before and 12 months after surgery. On the chest radiograph, the location of bullae, and the signs of compression and emphysema were evaluated. The radiographic total lung capacity (TLCX-ray) and the volume of bullae were measured according to the ellipse method. Postoperatively, functional and radiographic changes were analyzed. The percentage change in forced expiratory volume in 1 s(ΔFEV1%) after surgery was the main outcome measure. The influence of factors related to emphysema and bulla volume on the functional improvement postbullectomy was assessed by stepwise multiple regression. Results: Before surgery, the TLCx-ray overestimated the TLC measured by nitrogen washout, with a mean difference between the two measurements of 1.095 L. A close relationship was found between the TLCx-ray and the plethysmographic TLC (n=6; r=0.95). After surgery, dyspnea lessened (P<0.05) and FEV1 increased (P<0.01). Statistically, the radiographic bulla volume was the single most important factor determining the ΔFEV1% (r=0.80, P<0.0001). Conclusions: These findings suggest that the preoperative size of bullae is the most important contributor to the improvement in ventilatory capacity after bullectomy, and that it is possible to predict the expected increase of postoperative FEV1 from preoperative bulla volume

label free discrimination of cells undergoing apoptosis by hyperspectral confocual reflectance imaging

Among the optical techniques used for exploring the properties of cells and tissues, those based on hyperspectral label-free analysis are particularly interesting due to their non-invasive character and their ability to fast collect a huge number of information on the different sample constituents and their spatial distribution. Here we present results obtained with a novel hyperspectral reflectance confocal microscope of label-free discrimination of cells undergoing apoptosis. Our data, analyzed by means of a powerful statistical method, enable to obtain information on the biological status at a single cell level through the local measurement of reflectivity. Furthermore, an optical model of the local dielectric response gives an additional insight of the parameters linking the optical responsivity to the biological status

Chemical control of guava rust (Puccinia psidii) in the Northern Region of Rio de Janeiro State, Brazil.

Fungicides were evaluated under field conditions for their efficacy in the control of guava rust (Puccinia psidii); five systemic fungicides (azoxystrobin, pyraclostrobin, cyproconazole, tebuconazole, triadimenol) and the protectant mancozeb. In a first trial, the fungicides were applied at two-week intervals intercalated with bi-weekly sprays of copper oxychloride. The initial incidence of rust on flower buds before treatment was 47%. Triadimenol and azoxystrobin were most effective in reducing the incidence of rust on fruit. The minimum rust incidence achieved with triadimenol was 12% compared to 84% in the control treatment (water). The initial level of rust on flower buds was particularly high for the tebuconazole treatment, which may have contributed to the ineffective control by this fungicide in the first trial. In the second trial, copper oxychloride sprays were applied when disease incidence on flower buds was low (7%). Azoxystrobin, tebuconazole, triadimenol and mancozeb treatments were started nine days after a second application of copper oxychloride. The fungicides were then applied at bi-weekly intervals and at the same concentrations as in the first trial. Triadimenol was again most effective in controlling rust, although its effect did not greatly differ from that of tebuconazole. The maximum disease incidence in all fungicide treatments was significantly lower than that observed in the control treatment