Spin waves interference from rising and falling edges of electrical pulses

The authors have investigated the effect of the electrical pulse width of input excitations on the generated spin waves in a NiFe strip using pulse inductive time domain measurements. The authors have shown that the spin waves resulting from the rising- and the falling-edges of input excitation pulses interfere either constructively or destructively, and have provided conditions for obtaining spin wave packets with maximum intensity at different bias conditions

Dispersion and re-aggregation phenomena in carbon nanotube polymer composites

The preparation of polymer nanocomposites is usually carried out in twin-screw extruders or internal batch mixers. Previous studies have extensively shown that the resulting filler dispersion is strongly dependent on the characteristics of the melt mixing equipment. It is also known that the dispersion level of nanofillers strongly affects the final nanocomposite properties. The present work focuses on the study of the dispersion of carbon nanotubes (CNT) in polypropylene using a prototype mixer that develop high thermomechanical stress. The distribution and dispersion of the CNT was evaluated by optical and electron microscopy. The level of dispersion achieved was analysed, and the electrical resistivity of the composite, along the mixing cycles, was measured. The enhancement of the CNT dispersion along the mixing process correlated with a large decrease in electrical resistivity of the composite. A “percolation time”, defined as the time, or number of mixing cycles, required to achieve electrical conductivity, was measured, and correlated with mixing conditions. The composite formed was re-heated and reprocessed using the same mixing system. Re-agglomeration and loss of electrical conductivity was observed, and the final dispersion level varied with the mixing conditions imposed. Agglomerate size and electrical resistivity increased when reprocessing was performed at lower shear rate, as compared to the first processing cycle

Surface coupling effects on the capacitance of thin insulating films

A general form for the surface roughness effects on the capacitance of a capacitor is proposed. We state that a capacitor with two uncoupled rough surfaces could be treated as two capacitors in series which have been divided from the mother capacitor by a slit. This is in contrast to the case where the two rough surfaces are coupled. When the rough surfaces are coupled, the type of coupling decides the modification of the capacitance in comparison to the uncoupled case. It is shown that if the coupling between the two surfaces of the capacitor is positive (negative), the capacitance is less (higher) than the case of two uncoupled rough plates. Also, we state that when the correlation length and the roughness exponent are small, the coupling effect is not negligible

Short photoperiod-induced decrease of histamine H3 receptors facilitates activation of hypothalamic neurons in the Siberian Hamster

Nonhibernating seasonal mammals have adapted to temporal changes in food availability through behavioral and physiological mechanisms to store food and energy during times of predictable plenty and conserve energy during predicted shortage. Little is known, however, of the hypothalamic neuronal events that lead to a change in behavior or physiology. Here we show for the first time that a shift from long summer-like to short inter-like photoperiod, which induces physiological adaptation to winter in the Siberian hamster, including a body weight decrease of up to 30%, increases neuronal activity in the dorsomedial region of the arcuate nucleus (dmpARC) assessed by electro physiological patch-clamping recording. Increased neuronal activity in short days is dependent on a photoperiod-driven down-regulation of H3 receptor expression and can be mimicked in long-day dmpARC neurons by the application of the H3 receptor antagonist, clobenproprit. Short-day activation of dmpARC neurons results in increased c-Fos expression. Tract tracing with the trans-synaptic retrograde tracer, pseudorabies virus, delivered into adipose tissue reveals a multisynaptic neuronal sympathetic outflow from dmpARC to white adipose tissue. These data strongly suggest that increased activity of dmpARC neurons, as a consequence of down-regulation of the histamine H3 receptor, contributes to the physiological adaptation of body weight regulation in seasonal photoperiod

The prevalence of hepatitis B surface antigen and anti-hepatitis B core antibody in Iran: A population-based study

Background: Hepatitis B virus infection is a very common cause of chronic liver disease worldwide. It is estimated that 3 of Iranians are chronically infected with hepatitis B virus. Current population-based studies on both rural and urban prevalence of hepatitis B virus infection in Iran are sparse with results that do not always agree. We performed this study to find the prevalence of hepatitis B surface antigen, anti-hepatitis B core antibody, and associated factors in the general population of three provinces of Iran. Methods: We randomly selected 6,583 subjects from three provinces in Iran, namely Tehran, Golestan, and Hormozgan. The subjects were aged between 18 and 65 years. Serum samples were tested for hepatitis B surface antigen and anti-hepatitis B core antibody. Various risk factors were recorded and multivariate analysis was performed. Results: The prevalence of hepatitis B surface antigen and anti-hepatitis B core antibody in Iran was 2.6 and 16.4, respectively. Predictors of hepatitis B surface antigen or anti-hepatitis B core antibody in multivariate analysis included older age, not having high-school diploma, living in a rural area, and liver disease in a family member. We did not find any significant differences between males and females. Conclusion: In spite of nationwide vaccination of newborns against hepatitis B virus since 1992, hepatitis B virus infection remains a very common cause of chronic liver disease in Iran which should be dealt with for at least the next 30-50 years

Factors Affecting Minor Psychiatric Disorder in Southern Iranian Nurses: A Latent Class Regression Analysis

Background: Mental health is one of the most important dimensions of life and its quality. Minor Psychiatric Disorder as a type of mental health problem is prevalent among health workers. Nursing is considered to be one of the most stressful occupations. Objectives: This study aimed to evaluate the prevalence of minor psychiatric disorder and its associated factors among nurses in southern Iran. Patients and Methods: A cross-sectional study was carried out on 771 nurses working in 20 cities of Bushehr and Fars provinces in southern Iran. Participants were recruited through multi-stage sampling during 2014. The General Health Questionnaire (GHQ-12) was used for screening of minor psychiatric disorder in nurses. Latent Class Regression was used to analyze the data. Results: The prevalence of minor psychiatric disorder among nurses was estimated to be 27.5%. Gender and sleep disorders were significant factors in determining the level of minor psychiatric disorder (P Values of 0.04 and < 0.001, respectively). Female nurses were 20% more likely than males to be classified into the minor psychiatric disorder group. Conclusions: The results of this study provide information about the prevalence of minor psychiatric disorder among nurses, and factors, which affect the prevalence of such disorders. These findings can be used in strategic planning processes to improve nurses’ mental health