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The paper presents laboratory investigations of the response of a scaled down model of the Cassini spacecraft to impacts of submicron iron grains accelerated to velocities 5–25 km/s. The aim of the study is to help in a detailed analysis and interpretation of signals provided by the RPWS (Radio Wave Plasma Science) instrument that were attributed to dust impacts onto RPWS antennas or spacecraft body. The paper describes the experimental set-up, discusses its limitations, and presents the first results. Both monopole and dipole antenna configurations are investigated. We demonstrate that the amplitude and polarity of the impulse signals recorded by antenna amplifiers depend on the voltages applied onto the antennas or the spacecraft body and briefly introduce the mechanism leading to the signal generation. The experimental results support the recent suggestion by Ye et al. (2016) that antennas operated in a dipole mode are greatly insensitive to dust impacts on the spacecraft body. The pre-peak phenomenon, commonly observed in space, is also reproduced in the measurements and explained as the induced charge on the antenna from the impact plasma cloud that is becoming non-neutral due to the escape of the faster electrons. [ABSTRACT FROM AUTHOR]

Impact ionization of high-velocity cosmic dust particles has been used as a basic principle for dust detectors in space for many decades. It has provided optimum means to gain insight into the dust environment in the solar system. The Ulysses Dust Detector System provided for the first time impact ionization-based detection of interstellar dust (ISD) in the solar system and discovered surprisingly heavy ISD particles with sizes up to a few microns. Studies based on astronomical observations of the local interstellar medium, on the other hand, suggested a much smaller upper limit of around 0.25 ​μm (silica) or 1 ​μm (graphite) for the size distribution of ISD particles. Therefore, it has been suggested that low-density fluffy dust particles may mimic the impact signals of heavier compact particles. In this work, we discuss a series of impact experiments that have been performed at the Heidelberg dust accelerator facility with the Cosmic Dust Analyzer flight spare unit, to compare the high-velocity impact ionization properties of compact and hollow silicate particles, and carbon aerogel particles with each other and with literature data. The experiments indicate differences in the collected total amount of impact charges and how quickly the charges are collected, between impacts from compact particles and their non-compact counterparts. The results of this first study suggest that fluffy particles generate less ions upon impact than their compact counterparts, opposite to the suggested explanation for the heavy ISD particles. Data from the performed impact experiments indicate that a secondary process (e.g. secondary impacts from ejecta or more target material ionization) could be the main cause for the observed differences. These results imply that the previously detected heavy ISD particles may be real. We identify the key problems with the performed dust experiments and advise that future impact ionization instruments should additionally be calibrated with improved low-density fluffy dust particles that better represent the properties of cosmic dust particles. • Shows new results for impact ionization experiments with non-compact dust particles. • Secondary ionization processes may depend on particle structure and density. • Impact ejecta and target ionization are candidates for relevant secondary processes. • Large and porous in situ interstellar dust particles might likely be real. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Schizophrenia affects men more than women, but this may not be true at all ages. This study examines the incidence of first hospitalization for treatment of schizophrenia in each sex over different ages. Methods: We compared the incidence of first admission for treatment in a cohort of 46,388 males and 43,680 females followed from birth until ages 29–41, using life tables and proportional hazards methods. Results: Life table estimates of cumulative incidence by age 40 were 1.44% in males and 0.86% in females. For over all ages the relative risk (RR) in males was 1.6 (95% confidence limits=1.4–1.8) compared with females. Before age 17 there was no significant difference between the sexes (RR=0.86, 0.56–1.3). Excess risk in males was observed only from age 17 (RR=1.7, 1.4–1.9). There was no evidence of the incidence in females catching up with that in males, during the 30s. Conclusion: In this population, there was a significant change, over age, in the relative incidence of first hospitalization for schizophrenia between the sexes; the excess incidence in males first developed at age 17. [ABSTRACT FROM AUTHOR]

Objective: To investigate whether incidence of twin deliveries is related to father's age, independently of mother's age, and whether it differs for same-sex or opposite-sex twin sets.Study Design: In a program of research on effects of paternal age, this study used data from a prospective cohort of 92,408 offspring born in Jerusalem from 1964 to 1976. Of the 91,253 deliveries in the Jerusalem Perinatal Study, 1115 were twin deliveries. The data were analyzed with General Estimate Equations to inform unconditional logistic regression.Results: After controlling for maternal age, odds ratios (ORs) and 95% confidence intervals (95% CI) associated with father's ages 25-34 and 35+ were 1.3 (1.1, 1.7) and 1.5 (1.2, 2.1) respectively, compared with fathers <25 years old. The effect of maternal age was partly explained by paternal age. The ORs for opposite-sex twin sets and male-male twin sets increased slightly with paternal age, while the OR for same-sex and female-female twin decreased.Conclusion: Studies of twins are used to estimate effects of genes and environment in a variety of diseases. Our findings highlight the need to consider paternal as well as maternal age when analyzing data on twins to explore etiology of diseases. [ABSTRACT FROM AUTHOR]

We study the dynamics of radiation belt electrons during a 10-day quiet period perturbed by substorm activity and preceding a high-speed stream (HSS), aiming at a global description of the radiation belts in L-shell, L in [2, 6], and energy [0.1, 10] MeV. We combine Van Allen Probes observations and Fokker-Planck numerical simulations of pitch-angle diffusion. The Fokker-Planck model uses event-driven pitch angle diffusion coefficients from whistler-mode waves, built from the wave properties and the ambient plasma density measurements from the Van Allen Probes. We first find this event has some similar characteristics to regular quiet times previously studied; a widely extended plasmasphere within which we observe strong and varying whistler-mode waves. These ambient conditions lead to strong pitch-angle scattering, which contributes to the creation of a wide slot region as well as a significant decay of the outer radiation belts, which are observed and qualitatively well simulated. In addition, we find the substorm activity causes short duration (within ± 4h) decay of the plasma density and a lowering amplitude of the whistler-mode waves within the plasmasphere, both causing opposite effects in terms of pitch angle diffusion. This leads to a diminution of pitch-angle diffusion at the time of the main substorm activity. Conversely, whistler-mode waves become enhanced in the time periods between the substorm injections. All effects cumulated, we find an enhancement of pitch angle diffusion by whistler-mode waves above L~4.7 during the 10-day period. This directly relates to the combination of quietness and substorm activity which allows pitch angle diffusing of up to 1 MeV electrons in the outer belt. Relativistic electrons of 1–2 MeV remain trapped in the outer belt, from L~4.7 to L~5.2, forming, in both the observations and the simulations, a distinct pocket of remnant electrons. • Substorm injections cause a decay of the plasma density and whistler-mode hiss waves • Event-driven pitch-angle diffusion decreases at the time of substorm injections • Whistler-mode waves are enhanced in the time periods between the substorm injections • Over 10 days, mean pitch angle diffusion is enhanced by whistler-mode waves at L > 4.7 • Quiet and substorm times cause pitch angle-diffusion of outer belt electrons (<1 MeV) [ABSTRACT FROM AUTHOR]