Light-particle emission from the fissioning nuclei 126Ba, 188Pt and (266,272,278)/110: theoretical predictions and experimental results

We present a comparison of our model treating fission dynamics in conjunction with light-particle (n, p, alpha) evaporation with the available experimental data for the nuclei 126Ba, 188Pt and three isotopes of the element Z=110. The dynamics of the symmetric fission process is described through the solution of a classical Langevin equation for a single collective variable characterizing the nuclear deformation along the fission path. A microscopic approach is used to evaluate the emission rates for pre-fission light particles. Entrance-channel effects are taken into account by generating an initial spin distribution of the compound nucleus formed by the fusion of two deformed nuclei with different relative orientations

Precipitation-elevation relationship: Non-linearity and space–time variability prevail in the Swiss Alps

International audienceThe relationship between mean daily precipitation and elevation is often regarded as linear and positive, resulting in simple "precipitation lapse rate" equations frequently employed to extrapolate daily rainfall from a single weather station over a large area. We examine the precipitation-elevation relationship in the Swiss Alps using a combination of weather radar and rain gauge data to test this common assumption, challenging it by fitting a two-segment piecewise linear model with a mid-slope break-point as an alternative. By examining data stratified by catchment, season, and weather type, we assess the space-time variability of the precipitation-elevation relationship. We conclude that a non-linear and non-stationary model seems necessary to capture the variability of the observed precipitationelevation relationship. Based on our findings, we suggest that the simplified precipitation lapse rate concept is misleading and should be reconsidered in hydrological applications, emphasizing the need for a more realistic representation of precipitation variability over time and space

Defining Knowledge Management System Risk

Knowledge Management Systems are becoming widely used in organizations. Early successes are encouraging but these systems entail their own set of challenges. This paper proposes a measure of risk exposure for knowledge management system use. Five undesirable outcomes and thirty two risk factors were identified. These elements were extracted from the literature and from cases, and validated using a Delphi exercise. This measure enables knowledge managers to assess the level of risk supported by their organization and to take the appropriate action to manage their risk exposure

Essays on the Economics of Happiness.

The first chapter demonstrates that although it is possible to design utility functions that behave like empirical well-being, the functional forms relying on income adaptation and social comparisons put forward in the happiness literature fail to receive empirical validation. Under the income adaptation conjecture, utility functions that can convert the kind of economic expansion experienced in the US in a non-growing happiness flow exhibit extremely high levels of adaptation that are not observed in individual level regressions. Functions that represent the preferences of agents who compare their income with the income in their region fail to explain why richer countries tend to be happier. The second chapter of this dissertation shows that the lack of growth in average well-being, despite substantial GDP per capita growth, in the US is not a paradox. It can be explained by changes in the income distribution and the concavity of the happiness function. Since 1975 in the United-States practically all of the income gains have accrued to the richest 20% households. During that time, happiness has stagnated for the rich and fallen for the poor which is interpreted has rising happiness inequality. This pattern of spreading well-being between the income groups is also observed in Europe. These phenomena reflect the fact that although ``money buys happiness'', the relationship between the two is concave. The primary objective of the third chapter is to document how men and women happiness differ. The secondary objective of the paper is to test whether gender specific factors can explain the decline in happiness of American women since the mid-seventies. The paper finds that well-being follows very different trajectory for men and women. Women tend to be happier when they are young; their happiness falls when they enter the labor force and declines onward. Men's happiness rises until they enter the labor market. Unlike women, men tend to get happier after retirement. Somewhat surprisingly, the analysis finds that weekly work hours are positively associated with happiness. Gender differences are identified and the results are consistent with the idea that labor force participation takes time away from women's production of happiness.Ph.D.EconomicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/64721/1/jbgrou_1.pd

Critical Mass in Inter-Organizational Platforms

This paper examines how the critical mass challenge manifests itself during inter-organizational platform development. In previous research, critical mass is treated as an issue that occurs after platform launch. Strategies proposed, such as tactful pricing, opening the platform, user onboarding, and side-switching assume the platform to have already been launched. They may not work well in conditions where the platform is still under development. Over a two-and-a-half-year time period, this study traced the development of a data platform in a revelatory case within the New Zealand tourism sector. It revealed five critical mass issues faced by the platform sponsor in phases of development that occur before platform launch: (i) attracting initial interest, (ii) aligning heterogenous goals, (iii) sustaining commitment to the project (iv), negotiating architecture design, and (v) sustaining commitment to implementation. These findings provide a foundation for problematizing critical mass theory and its boundary conditions in inter-organizational platform development

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

ARTEFACTS: How do we want to deal with the future of our one and only planet?

The European Commission’s Science and Knowledge Service, the Joint Research Centre (JRC), decided to try working hand-in-hand with leading European science centres and museums. Behind this decision was the idea that the JRC could better support EU Institutions in engaging with the European public. The fact that European Union policies are firmly based on scientific evidence is a strong message which the JRC is uniquely able to illustrate. Such a collaboration would not only provide a platform to explain the benefits of EU policies to our daily lives but also provide an opportunity for European citizens to engage by taking a more active part in the EU policy making process for the future. A PILOT PROGRAMME To test the idea, the JRC launched an experimental programme to work with science museums: a perfect partner for three compelling reasons. Firstly, they attract a large and growing number of visitors. Leading science museums in Europe have typically 500 000 visitors per year. Furthermore, they are based in large European cities and attract local visitors as well as tourists from across Europe and beyond. The second reason for working with museums is that they have mastered the art of how to communicate key elements of sophisticated arguments across to the public and making complex topics of public interest readily accessible. That is a high-value added skill and a crucial part of the valorisation of public-funded research, never to be underestimated. Finally museums are, at present, undergoing something of a renaissance. Museums today are vibrant environments offering new techniques and technologies to both inform and entertain, and attract visitors of all demographics.JRC.H.2-Knowledge Management Methodologies, Communities and Disseminatio

Between but not within species variation in the distribution of fitness effects

New mutations provide the raw material for evolution and adaptation. The distribution of fitness effects (DFE) describes the spectrum of effects of new mutations that can occur along a genome, and is therefore of vital interest in evolutionary biology. Recent work has uncovered striking similarities in the DFE between closely related species, prompting us to ask whether there is variation in the DFE among populations of the same species, or among species with different degrees of divergence, i.e., whether there is variation in the DFE at different levels of evolution. Using exome capture data from six tree species sampled across Europe we characterised the DFE for multiple species, and for each species, multiple populations, and investigated the factors potentially influencing the DFE, such as demography, population divergence and genetic background. We find statistical support for there being variation in the DFE at the species level, even among relatively closely related species. However, we find very little difference at the population level, suggesting that differences in the DFE are primarily driven by deep features of species biology, and that evolutionarily recent events, such as demographic changes and local adaptation, have little impact

Accounting for rain type non-stationarity in sub-daily stochastic weather generators

Abstract. At sub-daily resolution, rain intensity exhibits a strong variability in space and time, which is favorably modelled using stochastic approaches. This strong variability is further enhanced because of the diversity of processes that produce rain (e.g. frontal storms, mesoscale convective systems, local convection), which results in a multiplicity of space-time patterns embedded into rain fields, and in turn leads to non-stationarity of rain statistics. To account for this non-stationarity in the context of stochastic weather generators, and therefore preserve the climatological coherence of rain simulations, we propose to resort to rain types simulation. We explore two methods to simulate rain type time series conditional to meteorological covariates: a parametric approach based on a non-homogeneous semi-Markov chain, and a non-parametric approach based on multiple-point statistics. Both methods are tested by cross-validation using a 17-year long rain type time series defined over central Germany. Evaluation results indicate that the non-parametric approach better simulates the relationships between rain types and meteorological covariates. Indeed, the inherent simplifications in the parametric model do not allow fully resolving complex and non-linear interactions between the rainfall statistics and meteorological covariates. The proposed approach is applied to generate rain type time series conditional to meteorological covariates simulated by a Regional Climate Model under an RCP8.5 emission scenario. Results indicate that, by the end of the century, the distribution of rain types could be modified over the area of interest, with an increased frequency of convective- and frontal-like rains at the expense of more stratiform events. </jats:p