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The KATRIN experiment aims to measure the effective electron antineutrino mass \\[m_{\\overline{\\nu }_e}\\] with a sensitivity of \\[{0.2}\\,{\\hbox {eV}/\\hbox {c}^2}\\] using a gaseous tritium source combined with the MAC-E filter technique. A low background rate is crucial to achieving the proposed sensitivity, and dedicated measurements have been performed to study possible sources of background electrons. In this work, we test the hypothesis that gamma radiation from external radioactive sources significantly increases the rate of background events created in the main spectrometer (MS) and observed in the focal-plane detector. Using detailed simulations of the gamma flux in the experimental hall, combined with a series of experimental tests that artificially increased or decreased the local gamma flux to the MS, we set an upper limit of \\[{0.006}\\,{\\hbox {count}/\\hbox {s}}\\] (90% C.L.) from this mechanism. Our results indicate the effectiveness of the electrostatic and magnetic shielding used to block secondary electrons emitted from the inner surface of the MS.

The KATRIN experiment aims to determine the effective electron neutrino mass with a sensitivity of \\[{0.2}{\\hbox { eV/c}^{2}}\\] (%90 CL) by precision measurement of the shape of the tritium \\[\\upbeta \\]-spectrum in the endpoint region. The energy analysis of the decay electrons is achieved by a MAC-E filter spectrometer. A common background source in this setup is the decay of short-lived isotopes, such as \\[{}^{\\text {219}}\\text {Rn}\\] and \\[{}^{\\text {220}}\\text {Rn}\\], in the spectrometer volume. Active and passive countermeasures have been implemented and tested at the KATRIN main spectrometer. One of these is the magnetic pulse method, which employs the existing air coil system to reduce the magnetic guiding field in the spectrometer on a short timescale in order to remove low- and high-energy stored electrons. Here we describe the working principle of this method and present results from commissioning measurements at the main spectrometer. Simulations with the particle-tracking software Kassiopeia were carried out to gain a detailed understanding of the electron storage conditions and removal processes.

Despite recommendations for rapidly initiating HIV treatment, many persons in sub-Saharan Africa present to care with advanced HIV disease. Baseline survey and clinical data were collected on 1799 adults newly enrolling at 32 district hospitals and local health HIV clinics in rural Ethiopia. Among those with complete HIV disease information, advanced HIV disease (defined as CD4 count <200 cells/mm3 or World Health Organization [WHO] HIV clinical stage III or IV disease) was present in 66% of males and 56% of females (P < .001). Males (compared to females) had lower CD4 counts (287 cells/mm3 versus 345 cells/mm3), lower body mass index (19.3 kg/m2 versus 20.2 kg/m2), and more WHO stage III or IV disease (46% versus 37%), (P < .001). Men reported more chronic diarrhea, fevers, cough, pain, fatigue, and weight loss (P < .05). Most initiating care in this resource-limited setting had advanced HIV disease. Men had poorer health status, supporting the importance of earlier diagnosis, linkage to care, and initiation of antiretroviral therapy.

The role of teacher intervention in preschoolers' peer conflicts is controversial, with one view suggesting that children should resolve conflicts on their own, and another that socialization accounts for conflict resolution's development. This study strives to clarify this issue using a short-term longitudinal, observational design to examine teacher intervention and 91 preschoolers aggressive competitive conflict. By delimiting the form of conflict, the study examines whether the role of teacher intervention varied by conflict behavior (e.g., physical and verbal aggression) and the form of conflict resolution. Results support the view that teacher intervention disrupts the conflict resolution cycle, especially in terms of preschoolers' on-going interaction and using alternatives to temporary separation. Implications for theory and practice are discussed.