A language and a system for program optimization

Hardware complexity has increased over time, and as architectures evolve and new ones are adopted, programs must often be altered by numerous optimizations to attain maximum computing power on each target environment. As a result, the code becomes unrecognizable over time, hard to maintain, and challenging to modify. Furthermore, as the code evolves, it is hard to keep the optimizations up to date. The need to develop and maintain separate versions of the application for each target platform is an immense undertaking, especially for the large and long-lived applications commonly found in the high-performance computing (HPC) community. This dissertation presents Locus, a new system, and a language for optimizing complex, long-lived applications for different platforms. We describe the requirements that we believe are necessary for making automatic performance tuning widely adopted. We present the design and implementation of a system that fulfills these requirements. It includes a domain-specific language that can represent complex collections of transformations, an interface to integrate external modules, and a database to manage platform-specific efficient code. The database allows the system’s users to access optimized code without having to install the code generation toolset. The Locus language allows the definition of a search space combined with the programming of optimization sequences separated from the application’s reference code. After all, we present an approach for performance portability. Our thesis is that we can ameliorate the difficulty of optimizing applications using a methodology based on optimization programming and automated empirical search. Our system automatically selects, generates, and executes candidate implementations to find the one with the best performance. We present examples to illustrate the power and simplicity of the language. The experimental evaluation shows that exploring the space of candidate implementations typically leads to better performing codes than those produced by conventional compiler optimizations that are based solely on heuristics. Locus was able to generate a matrix-matrix multiplication code that outperformed the IBM XLC internal hand-optimized version by 2× on the Power 9 processors. On Intel E5, Locus generates code with performance comparable to Intel MKL’s. We also improve performance relative to the reference implementation of up to 4× on stencil computations. Locus ability to integrate complex search spaces with optimization sequences can result in very complicated optimization programs. Locus compiler applies optimizations to remove from the optimization sequences unnecessary search statements making the exploration for faster implementations more accessible. We optimize matrix transpose, matrix-matrix multiplication, fast Fourier transform, symmetric eigenproblem, and sparse matrix-vector multiplication through divide and conquer. We implement three strategies using the Locus language to create search spaces to find the best shapes of the base case and the best ways of subdividing the problem. The search space representation for the divide-and-conquer strategy uses a combination of recursion and OR blocks. The Locus compiler automatically expands the recursion and ensures that the search space is correctly represented. The results showed that the empirical search was important to improve performance by generating faster base cases and finding the best splitting. We also use Locus to optimize large, complex applications. We match the performance of hand-optimized kernels of the Kripke transport code for different input data layouts. The Plascom2 multi-physics application is optimized to find the best way to use a multi-core CPU and GPU. The use of Tangram, Hydra, and OpenMP provided an interesting search space that improved performance by approximately 4.3× on ZAXPY and ZXDOTY kernels. Lastly, in a similar fashion to how a compiler works, we applied a search space representing a collection of optimization sequences to 856 loops extracted from 16 benchmarks that resulted in good performance improvements

A Model-Predictive Motion Planner for the IARA Autonomous Car

We present the Model-Predictive Motion Planner (MPMP) of the Intelligent Autonomous Robotic Automobile (IARA). IARA is a fully autonomous car that uses a path planner to compute a path from its current position to the desired destination. Using this path, the current position, a goal in the path and a map, IARA's MPMP is able to compute smooth trajectories from its current position to the goal in less than 50 ms. MPMP computes the poses of these trajectories so that they follow the path closely and, at the same time, are at a safe distance of eventual obstacles. Our experiments have shown that MPMP is able to compute trajectories that precisely follow a path produced by a Human driver (distance of 0.15 m in average) while smoothly driving IARA at speeds of up to 32.4 km/h (9 m/s).Comment: This is a preprint. Accepted by 2017 IEEE International Conference on Robotics and Automation (ICRA

Isolation and characterization of Faecalibacterium prausnitzii from calves and piglets.

The goal of our study was to isolate and characterize Faecalibacterium prausnitzii from fecal samples of healthy calves and piglets, in order to develop a novel probiotic for livestock animals. We identified 203 isolates of Faecalibacterium sp., which were clustered in 40 genetically distinct groups. One representative isolate from each cluster was selected for further characterization. The concentrations of the short chain fatty acids (SCFA) acetate, butyrate, propionate and isobutyrate in the culture media were measured by gas chromatography. We observed reduction in the concentration of acetate followed by concomitant increase in the concentration of butyrate, suggesting that the isolates were consuming acetate present in the media and producing butyrate. Butyrate production correlated positively with bacterial growth. Since butyrate has many benefits to the colonic epithelial cells, the selection of strains that produce higher amounts of butyrate is extremely important for the development of this potential probiotic. The effect of pH and concentration of bile salts on bacterial growth was also evaluated in order to mimic the conditions encountered by F. prausnitzii in vivo. The optimal pH for growth ranged between 5.5 and 6.7, while most isolates were inhibited by of the lowest concentration of bile salts tested (0.1%). Antimicrobial resistance profile showed that most isolates of Faecalibacterium sp. were resistant against ciprofloxacin and sulfamethoxazole-trimethoprim. More than 50% of the isolates were resistant to tetracycline, amikacin, cefepime and cefoxitin. A total of 19 different combinations of multidrug resistance were observed among the isolates. Our results provide new insights into the cultural and physiological characteristics of Faecalibacterium prausnitzii illustrating large variability in short chain fatty acid production, in vitro growth, sensitivity to bile salts, and antibiotic resistance and suggesting that future probiotic candidates should be carefully studied before elected for in vivo studies

Militarização das escolas públicas do distrito federal: uma análise sobre a violência

O artigo analisa o Projeto Piloto Escola de Gestão Compartilhada, que alterou quatro escolas públicas para colégios da Polícia Militar do Distrito Federal, no ano de 2019. São objetivos do trabalho: identificar os elementos legitimadores da instauração da gestão compartilhada, investigar se a violência é um fenômeno pertinente na eleição do projeto e detectar os medos da comunidade escolar. A estratégia de pesquisa utilizada foi o estudo de caso de um Colégio da Polícia Militar do Distrito Federal, e incita o debate sobre a violência escolar e a militarização das escolas públicas

Avaliação da via noradrenérgica e dos receptores alfa-2 e beta na modulação da analgesia induzida pela estimulação elétrica nervosa transcutânea de alta e de baixa frequência

Transcutaneous electric nerve stimulation is a noninvasive method used in clinical Physiotherapy to control acute or chronic pain. Different theories have been proposed to explain the mechanism of the analgesic action of transcutaneous electric nerve stimulation, as the participation of central and peripheral neurotransmitters. The aim of this study was to evaluate the involvement of noradrenergic pathway and of the receptors alfa-2 and beta in the modulation of analgesia produced by transcutaneous electric nerve stimulation of high and low frequency in Wistar rats after chronic treatment with propranolol or yohimbine intraperitoneally. Animals weighing 200 to 300 g were divided into 9 groups (n=8), which were obtained nociceptive thresholds through the Tail Flick before and after application of TENS for comparing the change of pain. The administration of yohimbine or propranolol at a dose of 3 mg/kg was effective in antagonizing the analgesia induced by high (150 Hz) and low (10 Hz) frequency transcutaneous electric nerve stimulation according to ANOVA test followed by Duncan post hoc test (pLa estimulación eléctrica nerviosa transcutánea es un método no invasivo utilizado en la clínica de Fisioterapia para controlar el dolor agudo y crónico. Diversas teorías son propuestas para explanar el mecanismo de acción analgésico de la estimulación eléctrica nerviosa transcutánea, como la participación de neurotransmisores centrales y periféricos. El objetivo del presente estudio fue evaluar la participación de la vía noradrenérgica y de los receptores alfa-2 y beta en la modulación de analgesia inducida por la estimulación eléctrica nerviosa transcutánea con alta y baja frecuencia en ratos del tipo Wistar, después del tratamiento crónico con yohimbina o propranolol por la vía intraperitoneal. Animales que pesaban 200 y 300 g fueron divididos en nueve grupos (n=8), por los cuales fueron obtenidos los umbrales nociceptivos por medio del Tail Flick, antes y después de la aplicación de la estimulación eléctrica nerviosa transcutánea con el intuito de comparar la alteración del cuadro álgico. La administración de yohimbina o propranolol en el dosis de 3 mg/kg fue eficaz en resultar en una antagonización de analgesia inducida por la estimulación eléctrica nerviosa transcutánea con alta (150 Hz) y baja (10 Hz) frecuencia, de acuerdo al test de ANOVA seguido del test post-hoc de Duncan (p>;0,05). Por lo tanto, se sugiere el envolvimiento de los receptores noradrenergicos alfa-2 y beta en la modulación de analgesia inducida por la estimulación eléctrica nerviosa transcutánea.Estimulação elétrica nervosa transcutânea é um método não invasivo utilizado na clínica de Fisioterapia para controlar dores aguda ou crônica. Diferentes teorias são propostas para explicar o mecanismo de ação analgésica da estimulação elétrica nervosa transcutânea, como a participação de neurotransmissores centrais e periféricos. O objetivo do presente estudo foi avaliar a participação da via noradrenérgica e dos receptores alfa-2 e beta na modulação da analgesia induzida pela estimulação elétrica nervosa transcutânea de alta e baixa frequência em ratos Wistar, após tratamento crônico com ioimbina ou propranolol por via intraperitoneal. Animais pesando entre 200 e 300 g foram divididos em 9 grupos (n=8), dos quais se obteve os limiares nociceptivos por meio do Tail Flick antes e após a aplicação da estimulação elétrica nervosa transcutânea para comparação de mudança do quadro álgico. A administração de ioimbina ou de propranolol na dose de 3 mg/kg foi efetiva em causar uma antagonização da analgesia induzida pela estimulação elétrica nervosa transcutânea de alta (150 Hz) e baixa frequência (10 Hz) segundo teste ANOVA seguido do teste post hoc Duncan (

Gestão do Capital de Giro em Micro e Pequenas Empresas

Este estudo tem como objetivo principal identificar como a gestão do capital de giro contribui para a manutenção das atividades das micro e pequenas empresas. Especificamente identificou as fontes de capital de giro das micro e pequenas empresas, como ocorre o fluxo desse recurso, os fatores que contribuem para a necessidade de capital de giro e os problemas enfrentados pela gestão do capital de giro nessas empresas. Para melhor análise do tema abordado e das suas implicações no contexto das micro e pequenas empresas, utilizou-se o método de estudo de casos múltiplos. Foram estudados os casos de duas empresas de porte diferente, uma microempresa e uma empresa de pequeno porte. As entrevistas foram baseadas em um roteiro, com questões abertas, elaborado a partir das categorias analíticas definidas para o estudo. Nos dois casos estudados, verificou-se que, apesar de as empresas serem de porte e setores distintos, os problemas enfrentados pela administração de capital de giro são muito semelhantes e que as ações adotadas para combatê-los são praticamente as mesmas. Identificou-se que as duas empresas apontam a inadimplência e o descasamento entre prazos de pagamento e de recebimento como os principais fatores que dificultam o processo de gestão do capital de giro. Palavras-chave: Capital de Giro. Gestão de Capital de Giro. Micro e Pequenas Empresas

Lack of effect of cell-wall targeted antibacterials on biofilm formation and antifungal susceptibility of Candida species

The use of central venous catheters (CVC) and broad-spectrum antibacterials are among the main risk factors for the development of candidemia in patients admitted to intensive care units (ICU). It is known that some antibacterials increase the resistance of these yeasts to azole antifungals. Thus, the aim of this research was to determine whether yeast present in CVC colonizations previously exposed to cell-wall targeted antibacterials benefit from a reduction in susceptibility to fluconazole and voriconazole, facilitating their ability to form biofilms. Candida albicans, C. tropicalis, C. glabrata, C. parapsilosis and C. guilhermondii were seeded into antibacterial (cefepime, meropenem, vancomycin, and piperacillin-tazobactam) gradient plates produced in Mueller-Hinton Agar. The susceptibility to fluconazole and voriconazole and the biofilm formation of the yeasts were tested before and after exposure to the antibacterials. None of the antibacterials exerted a significant effect on the in vitro susceptibility of the yeasts to the antifungal agents or on their ability to form biofilms. These results suggest that increased candidemia in ICU patients is not attributable to possible alterations in the yeasts, but is more likely caused by a weakening of the patient's general condition after long exposure to infection.O uso de cateter venoso central (CVC) e antibióticos de amplo espectro estão entre os principais fatores de risco para o desenvolvimento da candidemia em pacientes internados em unidades de terapia intensiva (UTI). É conhecido que alguns antibióticos aumentam a resistência das leveduras aos antifúngicos azólicos. Assim, o objetivo deste estudo foi avaliar se leveduras presentes em colonização de CVC expostas a antibióticos que atuam em parede celular se beneficiam de uma redução na suscetibilidade ao fluconazol e voriconazol e se obtêm maior capacidade de formar biofilme. Candida albicans, C. tropicalis, C. glabrata,C. parapsilosis e C. guilhermondii foram semeadas em placas de Mueller-Hinton Agar, com gradientes de antibióticos (cefepima, meropenem, vancomicina e piperacilina-tazobactam). A suscetibilidade e a formação de biofilme das leveduras foram testadas antes e após a exposição aos antibióticos. Nenhum dos antibióticos provocou alterações detectáveis in vitro sobre a suscetibilidade das leveduras aos antifúngicos ou à capacidade de formar biofilme. Estes resultados sugerem que o aumento da candidemia na UTI não seria atribuído a possíveis alterações provocadas nas leveduras e sim pelo enfraquecimento da condição geral do paciente após longa exposição à infecção

Phosphatidylserine Exposure by Toxoplasma gondii Is Fundamental to Balance the Immune Response Granting Survival of the Parasite and of the Host

Phosphatidylserine (PS) exposure on the cell surface indicates apoptosis, but has also been related to evasion mechanisms of parasites, a concept known as apoptotic mimicry. Toxoplasma gondii mimics apoptotic cells by exposing PS, inducing secretion of TGF-beta1 by infected activated macrophages leading to degradation of inducible nitric oxide (NO) synthase, NO production inhibition and consequently persisting in these cells. Here PS+ and PS− subpopulation of tachyzoites were separated and the entrance mechanism, growth and NO inhibition in murine macrophages, and mice survival and pathology were analyzed. Infection index in resident macrophages was similar for both PS subpopulations but lower when compared to the total T. gondii population. Growth in resident macrophages was higher for the total T. gondii population, intermediate for the PS+ and lower for the PS− subpopulation. Production of NO by activated macrophages was inhibited after infection with the PS+ subpopulation and the total populations of tachyzoites. However, the PS− subpopulation was not able to inhibit NO production. PS+ subpopulation invaded macrophages by active penetration as indicated by tight-fitting vacuoles, but the PS− subpopulation entered macrophages by phagocytosis as suggested by loose-fitting vacuoles containing these tachyzoites. The entrance mechanism of both subpopulations was confirmed in a non-professional phagocytic cell line where only the PS+ tachyzoites were found inside these cells in tight-fitting vacuoles. Both subpopulations of T. gondii killed mice faster than the total population. Clear signs of inflammation and no tachyzoites were seen in the peritoneal cavity of mice infected with the PS− subpopulation. Moreover, mice infected with the PS+ subpopulation had no sign of inflammation and the parasite burden was intense. These results show that PS+ and PS− subpopulations of T. gondii are necessary for a successful toxoplasma infection indicating that both subpopulations are required to maintain the balance between inflammation and parasite growth