21 research outputs found

    The neutron and its role in cosmology and particle physics

    Full text link
    Experiments with cold and ultracold neutrons have reached a level of precision such that problems far beyond the scale of the present Standard Model of particle physics become accessible to experimental investigation. Due to the close links between particle physics and cosmology, these studies also permit a deep look into the very first instances of our universe. First addressed in this article, both in theory and experiment, is the problem of baryogenesis ... The question how baryogenesis could have happened is open to experimental tests, and it turns out that this problem can be curbed by the very stringent limits on an electric dipole moment of the neutron, a quantity that also has deep implications for particle physics. Then we discuss the recent spectacular observation of neutron quantization in the earth's gravitational field and of resonance transitions between such gravitational energy states. These measurements, together with new evaluations of neutron scattering data, set new constraints on deviations from Newton's gravitational law at the picometer scale. Such deviations are predicted in modern theories with extra-dimensions that propose unification of the Planck scale with the scale of the Standard Model ... Another main topic is the weak-interaction parameters in various fields of physics and astrophysics that must all be derived from measured neutron decay data. Up to now, about 10 different neutron decay observables have been measured, much more than needed in the electroweak Standard Model. This allows various precise tests for new physics beyond the Standard Model, competing with or surpassing similar tests at high-energy. The review ends with a discussion of neutron and nuclear data required in the synthesis of the elements during the "first three minutes" and later on in stellar nucleosynthesis.Comment: 91 pages, 30 figures, accepted by Reviews of Modern Physic

    COVID-19 Working Paper: Food Insecurity During the First Year of the COVID-19 Pandemic in Four African Countries

    No full text
    This report analyzes trends in food security up to one year after the onset of the Coronavirus (COVID-19) pandemic in four African countries. Using household-level data collected by the World Bank, this report shows differences in food security over time during the pandemic between rural and urban areas as well as between female- and male-headed households in Burkina Faso, Ethiopia, Malawi, and Nigeria. Analysis of data collected during the pandemic shows a sharp increase in food insecurity in the early months of the pandemic with a subsequent gradual decline. Additionally, this report finds that a larger increase in food insecurity occurred in rural areas relative to urban areas within each of these countries. Finally, the authors found no systemic difference in food insecurity between female-headed and male-headed households. These trends, documented amid the first year of the COVID-19 pandemic, complement previous microeconomic analyses studying short-term changes in food security associated with the pandemic and macroeconomic projections based on expected changes to income, prices, and food supply

    COVID-19 Working Paper: Food Insecurity During the First Year of the COVID-19 Pandemic in Four African Countries

    No full text
    This report analyzes food security in the year after the onset of the Coronavirus (COVID-19) pandemic in four African countries. Using household-level data collected by the World Bank, this report describes differences in food security over time during the pandemic between rural and urban areas as well as between female- and male-headed households in Burkina Faso, Ethiopia, Malawi, and Nigeria. A sharp increase in food insecurity is observed during the early months of the pandemic before a gradual decline. Additionally, findings show a larger increase in food insecurity in rural areas relative to urban areas within each of these countries. Finally, no systemic difference in food insecurity is found between female-headed and male-headed households

    Food insecurity during the first year of the COVID-19 pandemic in four African countries

    No full text
    We document trends in food security up to one full year after the onset of the COVID-19 pandemic in four African countries. Using household-level data collected by the World Bank, we highlight differences over time amid the pandemic, between rural and urban areas, and between female-headed and male-headed households within Burkina Faso, Ethiopia, Malawi, and Nigeria. We first observe a sharp increase in food insecurity during the early months of the pandemic with a subsequent gradual decline. Next, we find that food insecurity has increased more in rural areas than in urban areas relative to pre-pandemic data within each of these countries. Finally, we do not find a systematic difference in changes in food insecurity between female-headed and male-headed households. These trends complement previous microeconomic analysis studying short-term changes in food security associated with the pandemic and existing macroeconomic projections.Economic Research ServiceNo embargo COVID-19This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

    Route of inoculation and mosquito vector exposure modulate dengue virus replication kinetics and immune responses in rhesus macaques

    No full text
    © Public Library of Science. All rights reserved. Dengue virus (DENV) is transmitted by infectious mosquitoes during blood-feeding via saliva containing biologically-active proteins. Here, we examined the effect of varying DENV infection modality in rhesus macaques in order to improve the DENV nonhuman primate (NHP) challenge model. NHPs were exposed to DENV-1 via subcutaneous or intradermal inoculation of virus only, intradermal inoculation of virus and salivary gland extract, or infectious mosquito feeding. The infectious mosquito feeding group exhibited delayed onset of viremia, greater viral loads, and altered clinical and immune responses compared to other groups. After 15 months, NHPs in the subcutaneous and infectious mosquito feeding groups were re-exposed to either DENV-1 or DENV-2. Viral replication and neutralizing antibody following homologous challenge were suggestive of sterilizing immunity, whereas heterologous challenge resulted in productive, yet reduced, DENV-2 replication and boosted neutralizing antibody. These results show that a more transmission-relevant exposure modality resulted in viral replication closer to that observed in humans
    corecore