37 research outputs found

    Unexpected high-energy γ emission from decaying exotic nuclei

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    Abstract The N = 52 Ga 83 β decay was studied at ALTO. The radioactive 83Ga beam was produced through the ISOL photofission technique and collected on a movable tape for the measurement of γ-ray emission following β decay. While β-delayed neutron emission has been measured to be 56–85% of the decay path, in this experiment an unexpected high-energy 5–9 MeV γ-ray yield of 16(4)% was observed, coming from states several MeVs above the neutron separation threshold. This result is compared with cutting-edge QRPA calculations, which show that when neutrons deeply bound in the core of the nucleus decay into protons via a Gamow–Teller transition, they give rise to a dipolar oscillation of nuclear matter in the nucleus. This leads to large electromagnetic transition probabilities which can compete with neutron emission, thus affecting the β-decay path. This process is enhanced by an excess of neutrons on the nuclear surface and may thus be a common feature for very neutron-rich isotopes, challenging the present understanding of decay properties of exotic nuclei

    A year of genomic surveillance reveals how the SARS-CoV-2 pandemic unfolded in Africa.

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    The progression of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic in Africa has so far been heterogeneous, and the full impact is not yet well understood. In this study, we describe the genomic epidemiology using a dataset of 8746 genomes from 33 African countries and two overseas territories. We show that the epidemics in most countries were initiated by importations predominantly from Europe, which diminished after the early introduction of international travel restrictions. As the pandemic progressed, ongoing transmission in many countries and increasing mobility led to the emergence and spread within the continent of many variants of concern and interest, such as B.1.351, B.1.525, A.23.1, and C.1.1. Although distorted by low sampling numbers and blind spots, the findings highlight that Africa must not be left behind in the global pandemic response, otherwise it could become a source for new variants

    The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance.

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    Investment in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing in Africa over the past year has led to a major increase in the number of sequences that have been generated and used to track the pandemic on the continent, a number that now exceeds 100,000 genomes. Our results show an increase in the number of African countries that are able to sequence domestically and highlight that local sequencing enables faster turnaround times and more-regular routine surveillance. Despite limitations of low testing proportions, findings from this genomic surveillance study underscore the heterogeneous nature of the pandemic and illuminate the distinct dispersal dynamics of variants of concern-particularly Alpha, Beta, Delta, and Omicron-on the continent. Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve while the continent faces many emerging and reemerging infectious disease threats. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

    The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

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    INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

    Est-ce que les variations de l'état de santé affectent la consommation de tabac ? Une étude sur données de panel britanniques

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    International audienceLes auteurs utilisent sept vagues d'un panel de ménages anglais (BHPS) pour étudier le lien entre variations passées de l'état de santé (à la fois celles du fumeur et celles des autres fumeurs de son ménage) et la consommation de cigarettes. On trouve que les fumeurs dont la santé se détériore ont une consommation moyenne moins élevée et une probabilité plus importante d'arrêter. Cette corrélation peut s'expliquer soit en faisant appel à un modèle de demande de santé classique de Grossman, soit à une hypothèse d'apprentissage du risque-santé du tabac en univers incertain. Les variations de santé des autres membres (fumeurs ou non) du ménage affectent peu les comportements. Par conséquent, une information impersonnelle sur les dangers du tabac devrait avoir moins d'effet sur le tabagisme qu'une prévention personnalisée menée, par exemple, par les professionnels de la santé

    Happy House: Spousal weight and individual well-being

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    We use life satisfaction and Body Mass Index (BMI) information from three waves of the GSOEP to test for social interactions in BMI between spouses. Semi-parametric regressions show that partner’s BMI is, beyond a certain level, negatively correlated with own satisfaction. Own BMI is positively correlated with satisfaction in thin men, and negatively correlated with satisfaction after some threshold. Critically, this latter threshold increases with partner’s BMI when the individual is overweight. The negative well-being impact of own BMI is thus lower when the individual’s partner is heavier. This is consistent with social contagion effects in weight. However, this cross-partial effect is insignificant in instrumental variable regressions, suggesting that the uninstrumented relationship reflects selection on the marriage market or omitted variables, rather than contagion.Obesity; subjective well-being; BMI; social interactions

    Modelling Heterogeneity in the Resilience to Major Socioeconomic Life Events

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    Using a novel, dynamic finite mixture model applied to 12 years of nationally representative panel data, we explore individual heterogeneity in the total psychological response (our measure of resilience) to ten major adverse life events, including serious illness, redundancy and crime victimisation. Importantly, this model takes into account that individuals are not randomly selected into adverse events, that some events are anticipated in advance of their occurrence, and that the immediate psychological response and the speed of adaptation may differ across individuals.Additionally, we generate a ‘standardised event’ in order to document the distribution of general resilience in the population. We find considerable heterogeneity in the response to adverse events, with the total psychological loss of people with low resilience being several times larger than the average loss. We also find that resilience is strongly correlated with clinical measures of mental health, but only weakly correlated with cognitive and non-cognitive traits. Finally, we find that resilience in adulthood to some extent is predictable by childhood socioeconomic circumstances; the strongest predictor we identify is good childhood health

    Measuring resilience to major life events

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    There is great interest in understanding who in the population is resilient in the face of major life events, and who is not. In this paper we construct a revealed measure of adulthood psychological resilience by modelling individuals’ responses to ten adverse life events using a dynamic finite mixture regression model applied to 17 years of panel data. Our methodology accounts for non-random selection into events, and differences between individuals in anticipation, immediate response, and speed of adaptation. We find considerable heterogeneity in individuals’ responses to events such as major financial shocks, redundancy and bereavement. We also find that our measure of resilience is correlated with clinical measures of mental health, and that it significantly predicts the psychological response to out-of-sample events. The strongest predictor of our measure of resilience is internal locus of control, which is an individual's belief that life outcomes are under their control
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