Temperature dependence of spin resonance in cobalt substituted NiZnCu ferrites

Cobalt substitutions were investigated in Ni0.4Zn0.4Cu0.2Fe2O4 ferrites, initial complex permeability was then measured from 1 MHz to 1 GHz. It appears that cobalt substitution led to a decrease in the permeability and an increase in the \mus\timesfr factor. As well, it gave to the permeability spectrum a sharp resonance character. We also observed a spin reorientation occurring at a temperature depending on the cobalt content. Study of the complex permeability versus temperature highlighted that the most resonant character was obtained at this temperature. This shows that cobalt contribution to second order magnetocrystalline anisotropy plays a leading role at this temperature

Temperature dependence of core loss in cobalt substituted Ni-Zn-Cu ferrites

The temperature dependence of core loss in cobalt substituted Ni-Zn-Cu ferrites was investigated. Co2+ ions are known to lead to a compensation of the magneto-crystalline anisotropy in Ni-Zn ferrites, at a temperature depending on the cobalt content and the Ni/Zn ratio. We observed similar behaviour in Ni-Zn-Cu and it was found that the core loss goes through a minimum around this magneto-crystalline anisotropy compensation. Moreover, the anisotropy induced by the cobalt allowed a strong decrease of core loss, a ferrite having a core loss of 350 mW/cm3 at 80 ^\circ C was then developed (measured at 1.5 MHz and 25 mT). This result represents an improvement of a factor 4 compared to the state of art Ni-Zn ferrites

Quality engineering of a traction alternator by robust design

Robust design is an engineering methodology for improving productivity during research and development so that high-quality products can be developed and produced quickly and at low cost. A large electrical company was developing traction alternators for a diesel electrical engine. Customer requirement was to obtain very high efficiency which, in turn, was influenced by several design parameters. The usual approach of the 'design-build-test' cycle was considered time-consuming and costly; it used to take anywhere from 4 months to 1 year before finalizing the product design parameters as it involved physical assembly and also testing. Instead, the authors used Taguchi's parameter design approach. This approach took about 8 weeks to arrive at optimum design parameter values; clearly demonstrating the cutting edge of this methodology over the traditional design-build-test approach. The prototype built and tested accordingly gave satisfactory overall performance, meeting and even exceeding customer requirements

Evidence of nitrification associated with globally distributed pelagic jellyfish

Often considered detrimental to the environment and human activities, jellyfish blooms are increasing in several coastal regions worldwide. Yet, the overall effect of these outbreaks on ecosystem productivity and structure are not fully understood. Here we provide evidence for a so far unanticipated role of jellyfish in marine nitrogen cycling. Pelagic jellyfish release nitrogen as a metabolic waste product in form of ammonium. Yet, we observed high rates of nitrification (NH4+ → NO3−, 5.7–40.8 nM gWW−1 [wet weight] h−1) associated with the scyphomedusae Aurelia aurita, Chrysaora hysoscella, and Chrysaora pacifica and low rates of incomplete nitrification (NH4+ → NO2−, 1.0–2.8 nM gWW−1 h−1) associated with Chrysaora fulgida, C. hysoscella, and C. pacifica. These observations indicate that microbes living in association with these jellyfish thrive by oxidizing the readily available ammonia to nitrite and nitrate. The four studied species have a large geographic distribution and exhibit frequent population outbreaks. We show that, during such outbreaks, jellyfish‐associated release of nitrogen can provide more than 100% of the nitrogen required for primary production. These findings reveal a so far overlooked pathway when assessing pelagic nitrification rates that might be of particular relevance in nitrogen depleted surface waters and at high jellyfish population densities

Seedlings production and initial growth in fields of Enterolobium contortisiliquum produced in different containers

O objetivo deste trabalho foi verificar a qualidade de mudas de Enterolobium contortisiliquum produzidas em sacos plásticos de 1.248 cm³, tubetes de 280 cm³ e tubetes de 180 cm³, e posteriormente avaliar a sobrevivência e o crescimento pós-plantio. Na fase de viveiro, todos os recipientes produziram mudas de qualidade, com destaque para as produzidas nos sacos plásticos. Na fase de campo, as plantas oriundas de saco plástico e de tubete 280 cm³ apresentaram 100% de sobrevivência, enquanto as de tubete de 180 cm³ apresentaram apenas 58%. Apesar de as mudas produzidas em sacos plásticos apresentarem maiores medidas na época de plantio, constatou-se que essa diferença tende a diminuir ou desaparecer com o tempo, pois as mudas produzidas nos tubetes apresentaram maior crescimento relativo. Para produção de mudas de Enterolobium contortisiliquum, podem-se utilizar sacos plásticos com capacidade 1.248 cm³ ou tubetes de 280 cm3.Palavras-chave: Tubetes; sacos plásticos; orelha-de-negro. AbstractSeedlings production and initial growth in fields of Enterolobium contortisiliquum produced in different containers. This research aims to verify the quality of Enterolobium contortisiliquum seedlings produced in plastic bags of 1.248 cm³, tubes of 280 cm³, and tubes of 180 cm³, as well as evaluate their survival and growth after planting. In nursery stage, all containers resulted in quality seedlings, especially those produced in plastic bags. In field phase, plants from plastic bag and tubes 280 cm³ had 100% survival, while to the ones from tube of 180 cm ³ survival was only 58%. Despite seedlings produced in plastic bags present greatest measures in planting season, such difference tends to disappear in time, because the seedlings grown in tubes had higher relative growth. We recommend plastic bags of 1.248 cm³ and tubes of 280 cm³.Keywords: Tubes; plastic bags; orelha-de-negro.AbstractThis research aims to verify the quality of Enterolobium contortisiliquum seedlings produced in plastic bags of 1.248 cm³, tubes of 280 cm³, and tubes of 180 cm³, as well as evaluate their survival and growth after planting. In nursery stage, all containers resulted in quality seedlings, especially those produced in plastic bags. In field phase, plants from plastic bag and tubes 280 cm³ had 100% survival, while to the ones from tube of 180 cm ³ survival was only 58%. Despite seedlings produced in plastic bags present greatest measures in planting season, such difference tends to disappear in time, because the seedlings grown in tubes had higher relative growth. We recommend plastic bags of 1.248 cm³ and tubes of 280 cm³.Keywords: Tubes; plastic bags; orelha-de-negro

Paradigms in multiple sclerosis: time for a change, time for a unifying concept

It has recently been suggested that, rather than being an autoimmune disease, multiple sclerosis (MS) is an example of a neurocristopathy, a pathological process resulting from a faulty development of the neural crest. Whilst several characteristics of the disease suggest a neurocristopathy, other aetiological factors require consideration, including hygiene-related factors that alter the immune responses to common pathogens resulting in an eclipse of immune reactivity that could protect against MS, the possible role of human endogenous retroviruses (HERVs) in pathogenesis and autoimmune phenomena, HLA polymorphism, vitamin D levels before and after birth and immune repair mechanisms. A postulated aetiological factor in MS, associated with altered vitamin D metabolism and abnormal HERV expression, is a long-lasting disturbed redox regulation in the biosynthesis of a melanoma-like melanin pigment. Although intensive further studies on melanin pigments in nerve tissue in MS are required, the known properties of a pathological form of such pigments in melanoma could explain a number of observations in MS, including the impact of light, UV-light, and vitamin D, and could explain the clinical manifestations of MS on the basis of an oscillating process of oxidative charge and discharge of the pigments and a threshold phenomenon with a change of the quasi-catalytic function of the pigment from destroying reactive oxygen radicals or species to transforming them to more harmful long-persisting highly reactive species. Taken together with the consequences of an adaptive process in partly demyelinated neurons, resulting in an increase in number of mitochondria, and the impact of stressful life events, these conditions are necessary and sufficient to explain the disease process of MS with its spatial (plaques) and temporal (attacks and remissions) characteristics. This suggested unifying concept of the pathogenesis of MS may open perspectives for prevention, diagnosis and therapy. In particular, prevention may be achieved by vaccinating against Epstein-Barr virus in early childhood

Periodization and self-regulation in action sports: Coping with the emotional load

Action sports usually include some danger and personal challenge. The levels of both are often further increased when the sport is placed in a competitive environment. In this paper, we consider the Olympic disciplines of freeskiing and snowboarding in park and pipe. We consider some pertinent theoretical perspectives, then offer some insights on their operation using a range of data from ongoing research and support work. Finally, we offer a number of practical steps which can be taken to optimize performance, both in learning and practicing new tricks and in executing them under the pressures of competition

Market ecologies: The effect of information on the interaction and profitability of technical trading strategies

Technical trading strategies make profits by identifying and exploiting patterns in market prices—patterns generated by the interaction of market participants. Using a model market populated by individuals using a range of trading rules we show that the presence of technical traders may be beneficial, in some cases reducing volatility and increasing price efficiency. In particular, contrarian traders who base their decisions on high frequency data have the largest positive effect. It is also found that if technical traders condition their actions using ‘real time’ information, they partially emulate arbitrageurs and make positive profits

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

Bioprospecção de Fungos de um Fragmento de Cerrado no Brasil Central para Aplicações Biotecnológicas

Considering the importance of bio-prospection studies involving species from threatened environments that are of great biological richness and endemism, this work aimed to investigate the biotechnological potential of fungi from different habitats in a fragment of Cerrado. The fungi were isolated in culture, and some were selected for the prospection of enzymes that are of industrial interest, for antimicrobial activity and preliminary toxicity. Carboxymethyl cellulose and peroxidase activity was detected in all isolates evaluated. In the tests for antimicrobial activity, the fungal metabolites did not show growth inhibition for the bacterial strains analyzed, and in the toxicity assays these metabolites were shown to be innocuous for Artemia salina larvae. Although the toxicity evaluation still requires complementary assays, these results justify the continuation of bio-prospection studies on the biotechnological potential of these fungi, showing them to be promising candidates for use in processes applied directly to humans or to the environment.Considerando a importância dos estudos de bioprospecção de espécies de ambientes ameaçados, de grande riqueza biológica e endemismo, esse trabalho visou investigar o potencial biotecnológico de espécies fúngicas de diferentes hábitats de um fragmento de Cerrado. Os fungos foram isolados em cultura, algumas das quais selecionadas para a prospecção de enzimas de interesse industrial, atividade antimicrobiana e toxicidade preliminar. Foi detectada atividade de carboximetilcelulase e peroxidase em todos os isolados avaliados. Nos testes para atividade antimicrobiana, os metabólitos fúngicos não mostraram inibição do crescimento para as cepas bacterianas analisadas, da mesma forma que nos ensaios de toxicidade, esses metabólitos se mostraram inócuos para larvas de Artemia salina. Ainda que a avaliação da toxicidade requeira ensaios complementares, esses resultados estimulam a continuidade dos estudos para a bioprospecção do potencial biotecnológico destes fungos, apontando-os como candidatos promissores para serem empregados em processos de aplicação direta ao homem ou ao meio ambiente