O uso de videogames, jogos de computador e internet por uma amostra de universitários da Universidade de São Paulo

OBJETIVO: Avaliar uso de jogos eletrônicos (videogames, jogos de computador e internet) em uma amostra de universitários. MÉTODO: Um questionário a respeito de comportamentos relacionados ao uso de jogos eletrônicos, contendo a escala Problem Videogame Playing (PVP), foi aplicado em 100 alunos da Universidade de São Paulo (USP). RESULTADOS: A maioria (83%) relatou ter jogado no último ano, dentre a qual 81,9% eram homens, 51,8% jogavam de 1 a 2 horas por sessão; 74,4% afirmaram que jogar não interfere em seus relacionamentos sociais e 60,5%, que o uso de jogos violentos não influencia sua agressividade. Os estudantes dividiram-se entre jogadores ocasionais e frequentes, diferenciando-se por duração de cada sessão, jogo preferido, motivação para jogar, e influência do jogo na vida social. Cerca de 5% relataram só parar de jogar quando interrompidos, normalmente jogar mais de 4 horas por sessão e se relacionar mais com amigos virtuais, sugerindo maior envolvimento com a atividade. Na escala PVP, 15,8% da amostra preencheu mais da metade dos itens, indicando consequências adversas associadas ao uso dos jogos eletrônicos. CONCLUSÃO: Observou-se que o uso de jogos eletrônicos é comum entre os estudantes da USP e que uma parcela apresenta problemas relacionados ao excesso de jogo.

Estudo do mecanismo de corrosão por pites em água do mar de aços inoxidáveis supermartensíticos microligados com Nb e Ti

Os aços inoxidáveis supermartensíticos (SMSS) são usados em ambientes agressivos devido à sua boa soldabilidade, boas propriedades mecânicas em temperaturas elevadas e superior resistência à corrosão sob tensão. Aplicações na exploração de petróleo demandam superior combinação de propriedades e os aços inoxidáveis duplex e superduplex têm sido aplicados nessa área, a despeito de seus custos elevados. Os SMSS consistem numa alternativa técnica e econômica ao uso daqueles aços. Nesse trabalho, adições de Nb e Ti foram realizadas com o intuito de minimizar o efeito de sensitização, promover o refino de grãos e foram estudados os aspectos microestruturais e a resistência à corrosão por pites em água do mar. A formação e a evolução dos pites foram acompanhadas por ensaios de corrosão, microscopia óptica e eletrônica, focalizando suas morfologias. O aço com Ti apresentou o melhor desempenho quanto à corrosão, com o maior potencial de corrosão e menor potencial de pite entre os aços em estudo. O aço com Nb, apesar de apresentar potencial de corrosão superior ao do aço sem adição, teve um potencial de pite inferior ao do mesmo.

The effect of using mixed initiator systems on the efficiency of photopolymerization of dental resins

A study was performed in order to determine the efficiency of the simultaneous use of the photoinitiators phenylpropanedione (PPD) and camphorquinone (CQ) in the polymerization of acrylic polymers and evaluate possible mechanisms leading to synergism or antagonism. It was found that efficiencies of both initiators taken individually are higher than that of their mixture, indicating that when both dyes are used simultaneously there will be an energy transfer from the more efficient initiator (CQ) to the less efficient one (PPD). Also, there was no proof of any reaction between the amine present in the CQ formulation and the PPD excited state.

Effect of temperature on the electro-oxidation of ethanol on platinum

We present in this work an experimental investigation of the effect of temperature (from 25 to 180 ºC) in the electro-oxidation of ethanol on platinum in two different phosphoric acid concentrations. We observed that the onset potential for ethanol electro-oxidation shifts to lower values and the reaction rates increase as temperature is increased for both electrolytes. The results were rationalized in terms of the effect of temperature on the adsorption of reaction intermediates, poisons, and anions. The formation of oxygenated species at high potentials, mainly in the more diluted electrolyte, also contributes to increase the electro-oxidation reaction rate.

Electronic conduction and electrocatalysis by supramolecular tetraruthenated copper porphyrazine films

A new tetraruthenated copper(II)-tetra(3,4-pyridyl)porphyrazine species, [CuTRPyPz]4+, has been synthesized and fully characterized by means of analytical, spectroscopic and electrochemical techniques. This À-conjugated system contrasts with the related meso-tetrapyridylporphyrins by exhibiting strong electronic interaction between the coordinated peripheral complexes and the central ring. Based on favorable À-stacking and electrostatic interactions, layer-by-layer assembled films were successfully generated from the appropriate combination of [CuTRPyPz]4+ with copper(II)-tetrasulfonated phtalocyanine, [CuTSPc]4-. Their conducting and electrocatalytic properties were investigated by means of impedance spectroscopy and rotating disc voltammetry, exhibiting metallic behavior near the Ru(III/II) redox potential, as well as enhanced catalytic activity for the oxidation of nitrite and sulphite ions.

Effect of experimental heat treatment on mechanical properties of resin composites

The aim of this study was to verify the influence of an experimental heat treatment (170ºC/10 min) using a casting furnace on the mechanical properties (hardness and flexural strength) of 2 commercial direct resin composites (TPH Spectrum and Filtek P60) compared to a commercial indirect resin system (BelleGlass). Heat treatment temperature was determined after thermal characterization by thermogravimetry (TG) and differential scanning calorimetry (DSC). Data was analyzed by ANOVA and Tukey's test at 5% significance level. There was statistical significance for the main factor heat treatment (p=0.03) and composite (p=0.02), for flexural strength. For Knoop hardness, only the main factor composite was statistically significant (p=0.00). P60 presented higher hardness than TPH. No statistically significant correlation between mechanical properties tested was detected. Based on these results, it was possible to conclude that heat treatment influenced flexural strength of direct composites, while it was not observed for hardness. The association of direct composites with a simple post-cure heat treatment may be an alternative for current indirect composite systems, although more studies are needed to verify other properties of the composites for this application.

Effect of cold fronts on the benthic macrofauna of exposed sandy beaches with contrasting morphodynamics

The aim of this study was to determine the short-term environmental changes caused by the simultaneous passage of a high energy event on two sandy beaches with different morphodynamic states and their influence on the richness, abundance and distribution of the benthic macrofauna. Two microtidal exposed sandy beaches with contrasting morphodynamics were simultaneously sampled before, during and after the passage of two cold fronts in Santa Catarina. The reflective beach showed a higher susceptibility to the increase in wave energy produced by the passage of cold fronts and was characterized by rapid and intense erosive processes in addition to a capacity for rapid restoration of the beach profile. As regards the dissipative beach, erosive processes operated more slowly and progressively, and it was characterized further by a reduced capacity for the recovery of its sub-aerial profile. Although the intensity of the environmental changes was distinct as between the morphodynamic extremes, changes in the composition, richness and abundance of macrobenthos induced by cold fronts were not evident for either of the beaches studied. On the other hand, alterations in the distribution pattern of the macrofauna were observed on the two beaches and were related to variations in sea level, position of the swash zone and moisture gradient, suggesting that short-term accommodations in the spatial structure of the macrobenthos occur in response to changes in environmental conditions in accordance with the temporal dynamics characteristic of each morphodynamic state.

Effect of morphodynamics on annual average zonation pattern of benthic macrofauna of exposed sandy beaches in Santa Catarina, Brazil

This study investigated the effect of environmental factors on the annual average zonation pattern of benthic macrofauna of sub-aerial profile of three exposed sandy beaches of Santa Catarina with different morphodynamic characteristics. Sampling was carried out between March 2000 and March 2001, with monthly frequency on reflective and dissipative morphodynamic extremes and bimonthly frequency on the intermediate state. Results showed that macrobenthic zonation presented marked differences across the morphodynamic spectrum. The main differences observed from reflective to dissipative conditions were: a) increase in the number of species in lower zones of the beach; b) expansion of zones characterized by high water content of sediment and c) increase in the overlapping of zones, mainly on lower levels of the beach. Canonical Correspondence Analysis related these differences to distinctive cross-shore gradients in sediment moisture levels, sediment reworking and mean grain size that exist across the morphodynamic spectrum, showing that it is important to analyze these environmental factors in studies conducted to investigate zonation on microtidal exposed sandy beaches.

Effect of CO2 and 1-octen-3-ol attractants for estimating species richness and the abundance of diurnal mosquitoes in the southeastern Atlantic forest, Brazil

Studies have shown that both carbon dioxide (CO2) and octenol (1-octen-3-ol) are effective attractants for mosquitoes. The objective of the present study was to evaluate the attractiveness of 1-octen-3-ol and CO2 for diurnal mosquitoes in the southeastern Atlantic forest. A Latin square experimental design was employed with four treatments: CDC-light trap (CDC-LT), CDC-LT and 1-octen-3-ol, CDC-LT and CO2 and CDC-LT with 1-octen-3-ol and CO2. Results demonstrated that both CDC-CO2 and CDC-CO2-1-octen-3-ol captured a greater number of mosquito species and specimens compared to CDC-1-octen-3-ol; CDC-LT was used as the control. Interestingly, Anopheles (Kerteszia) sp. was generally attracted to 1-octen-3-ol, whereas Aedes serratus was the most abundant species in all Latin square collections. This species was recently shown to be competent to transmit the yellow fever virus and may therefore play a role as a disease vector in rural areas of Brazil.

Condições socioeconômicas e câncer de cabeça e pescoço: uma revisão sistemática de literatura

O presente estudo teve como objetivo descrever as principais características dos estudos epidemiológicos que investigaram a associação entre condições socioeconômicas e câncer de cabeça e pescoço. Foram pesquisadas as bases de dados Medline (Literatura Internacional em Ciências), Lilacs (Literatura Latino-Americana e do Caribe em Ciências da Saúde) e Scielo (Scientific Electronic Library Online), além de referências citadas nos artigos obtidos a partir da busca primária nessas bases. O período de publicação considerado englobou 38 anos (1970-2007) e a análise restringiu-se aos artigos em espanhol, inglês ou português. Foram selecionados 25 estudos, 15 com delineamento caso-controle, quatro ecológicos e seis que mesclaram informações de bases de dados oficiais, como censos e registros de câncer ou de óbitos. A maior parte das pesquisas reportou associação entre piores condições socioeconômicas e câncer de cabeça e pescoço. Os indicadores mais empregados foram a ocupação e a escolaridade. Poucos estudos investigaram mediação, procurando evidenciar quais os fatores proximais operam na associação investigada. Pesquisas adicionais, com critérios uniformes para proceder aos ajustes nos modelos de regressão e amostra suficiente, são necessárias para investigar essa dimensão.

Effect of an energy-deficient diet on populations of ciliate protozoans in bovine rumen

Ten young rumen-cannulated crossbred steers were randomly divided into two groups: a control group (C; n=4), which was fed a balanced diet for daily weight gain of 900g; and a pronounced energy-deprived group (PED; n=6), receiving 30% less of the required energy for maintenance. After 140 days of these alimentary regimes, rumen fluid and urine samples were collected for biochemical and functional tests, before feeding and at 1, 3, 6, and 9 hours after feeding. The energy-deprivation diet caused a significant reduction in the number of Entodinium, Eodinium, Isotricha, Dasytricha, Eremoplastron, Eudiplodinium, Metadinium, Charonina, Ostracodinium, and Epidinium protozoa. There was no effect of the time of sampling in both groups on the total number of ciliates in rumen fluid. A higher number of protozoan forms in binary division were recorded in the control group, at the 6th and 9th hours after feeding (P<0.019). There was a high positive correlation between the total count of protozoans in rumen fluid and glucose fermentation, ammonia, and urinary allantoin excretion index; and a negative correlation between the total count of protozoa and metilene blue reduction, and a medium correlation between the total count of protozoa and total volatile fatty acids concentration. The determination of the protozoa populations does not imply in the use of complex and hard-to-execute techniques, although it is time consuming and needs practice. This exam particularly helps in clinical expected diagnosis.

Effect of the kappa-casein gene polymorphism, breed and seasonality on physicochemical characteristics, composition and stability of bovine milk

The objective of this study was to evaluate the effect of genetic polymorphism of kappa-casein, breed and seasonality on the physicochemical characteristics, composition and stability of milk in commercial dairy herds. A total of 879 milk and blood samples were collected from 603 Holstein and 276 Girolando cows, obtained during rainy and dry seasons. Milk samples were analyzed to determine the physicochemical characteristics, composition and ethanol stability, while blood samples were subjected to polymerase chain reaction to identify the kappa-casein genotype. The frequencies of genotypes AA, AB and BB of k-casein were respectively, 66.83, 31.84 and 1.33% for Holstein, and 71.38, 27.90 and 0.72% for the Girolando cows, respectively. The A allele was more frequent than the B allele, both for Holstein (0.827 and 0.173) and Girolando cows (0.853 and 0.147), respectively. Cows of AB and BB genotypes showed a higher milk fat content compared to the AA genotype. There was an interaction between breed and seasonality on the concentration of milk urea with higher values for Holstein and Girolando cows in the rainy and dry season, respectively. The levels of lactose, total solids, crude protein, true protein, casein and the casein:true protein ratio were higher during the dry season, while during the rainy season, the somatic cell count and milk urea concentration were higher. There was no association between milk stability and k-casein genotypes, but Holstein cows showed higher milk stability than Girolando cows, and milk was more stable during the rainy season than during the dry season.

Effect of cyhalothrin on Ehrlich tumor growth and macrophage activity in mice

Cyhalothrin, a pyrethroid insecticide, induces stress-like symptoms, increases c-fos immunoreactivity in the paraventricular nucleus of the hypothalamus, and decreases innate immune responses in laboratory animals. Macrophages are key elements in cellular immune responses and operate at the tumor-host interface. This study investigated the relationship among cyhalothrin effects on Ehrlich tumor growth, serum corticosterone levels and peritoneal macrophage activity in mice. Three experiments were done with 10 experimental (single gavage administration of 3.0 mg/kg cyhalothrin daily for 7 days) and 10 control (single gavage administration of 1.0 mL/kg vehicle of cyhalothrin preparation daily for 7 days) isogenic BALB/c mice in each experiment. Cyhalothrin i) increased Ehrlich ascitic tumor growth after ip administration of 5.0 x 106 tumor cells, i.e., ascitic fluid volume (control = 1.97 ± 0.39 mL and experimental = 2.71 ± 0.92 mL; P < 0.05), concentration of tumor cells/mL in the ascitic fluid (control = 111.95 ± 16.73 x 106 and experimental = 144.60 ± 33.18 x 106; P < 0.05), and total number of tumor cells in the ascitic fluid (control = 226.91 ± 43.22 x 106 and experimental = 349.40 ± 106.38 x 106; P < 0.05); ii) increased serum corticosterone levels (control = 200.0 ± 48.3 ng/mL and experimental = 420.0 ± 75.5 ng/mL; P < 0.05), and iii) decreased the intensity of macrophage phagocytosis (control = 132.3 ± 19.7 and experimental = 116.2 ± 4.6; P < 0.05) and oxidative burst (control = 173.7 ± 40.8 and experimental= 99.58 ± 41.7; P < 0.05) in vitro in the presence of Staphylococcus aureus. These data provide evidence that cyhalothrin simultaneously alters host resistance to Ehrlich tumor growth, hypothalamic-pituitary-adrenocortical (HPA) axis function, and peritoneal macrophage activity. The results are discussed in terms of data suggesting a link between stress, HPA axis activation and resistance to tumor growth.

Storage effect on the acceptability of snacks made of pure amaranth and blends of amaranth and corn or chickpea

Snacks made by extrusion cooking of pure amaranth flour or mixtures of 80 per cent amaranth flour and 20 per centcorn grits or chickpea flour were developed to replace the traditional commercial ones with improved nutritional and functional quality. Pure amaranth snacks and the blended ones were flavored with salty and sweet flavors and evaluated for acceptability using a 9-point hedonic scale. The good acceptance observed for either salty or sweet flavored snacks indicated that they have characteristics to compete with similar commercial products. Acceptability of salty snacks increased with storage time at room temperature in BOPP (polypropylene bi-guided) packs whereas slightly decreased for the sweet ones. This type of storage proved to be very efficient for the conservation of the salty product and also suitable for the sweet ones

Effect of fructans-based fat replacer on chemical composition, starch digestibility and sensory acceptability of corn snacks

To develop a convenience healthy food snack the partially hydrogenated vegetable fat, used as the flavour fixative agent, was replaced by a non-fat-flavouring solution enriched with inulin and oligofructose. The effects of this replacement on chemical composition, in vitro rate of starch digestion and sensory acceptability were assessed. The new snack presented low-fat levels (0.1 per cent) and around a sevenfold increase in dietary fibre (15.3 per cent of dietary fibre, being 13.3 per cent of fructans) when compared with the traditional ones. The enrichment with fructans reduced the predicted Glycaemic Index by 25 per cent, thus indicating that this dietary fibre contributes effectively towards delaying the in vitro glycaemic response. Fructans-enriched snack presented overall acceptability score (6.6 ± 1.7) similar to the traditional one, flavoured with fatty fixative agent (7.4 ± 1.4). The healthy low-fat fibre-enriched snack produced presented the high sensory acceptability typical for this food product type