Suchergebnisse

Abstract. Wet snow icing accretion on power lines is a real problem in Italy, causing failures on high and medium voltage power supplies during the cold season. The phenomenon is a process in which many large and local scale variables contribute in a complex way and not completely understood. A numerical weather forecast can be used to select areas where wet snow accretion has an high probability of occurring, but a specific accretion model must also be used to estimate the load of an ice sleeve and its hazard. All the information must be carefully selected and shown to the electric grid operator in order to warn him promptly. The authors describe a prototype of forecast and alert system, WOLF (Wet snow Overload aLert and Forecast), developed and applied in Italy. The prototype elaborates the output of a numerical weather prediction model, as temperature, precipitation, wind intensity and direction, to determine the areas of potential risk for the power lines. Then an accretion model computes the ice sleeves' load for different conductor diameters. The highest values are selected and displayed on a WEB-GIS application principally devoted to the electric operator, but also to more expert users. Some experimental field campaigns have been conducted to better parameterize the accretion model. Comparisons between real accidents and forecasted icing conditions are presented and discussed.

We present new probabilistic forecasts of the timing of the world's population reaching 8 billion, the world's peak population, and the date at which one‐third or more of the world's population would be 60+ years old. The timing of these milestones, as well as the timing of the Day of 7 Billion, is uncertain. We compute that the 60 percent prediction interval for the Day of 8 Billion is between 2024 and 2033. Our figures show that there is around a 60 percent chance that one‐third of the world's population would be 60+ years old in 2100. In the UN 2010 medium variant, that proportion never reaches one‐third. As in our past forecasts (Lutz et al. 2001, 2008), we find the chance that the world's population will peak in this century to be around 84 percent and the timing of that peak to be highly uncertain. Focal days, like the Day of 7 Billion, play a role in raising public awareness of population issues, but they give a false sense of the certainty of our knowledge. The uncertainty of the timing of demographic milestones is not a constant of nature. Understanding the true extent of our demographic uncertainty can help motivate governments and other agencies to make the investments necessary to reduce it.

PurposeThe purpose of this paper is to study the impact of the 2007 Italian severance payment reform on the cost and the access to credit for small‐ and medium‐sized enterprises (SMEs).Design/methodology/approachThe authors study the implications of the reform adapting the theoretical credit‐rationing model of Holmstrom and Tirole, then estimate the capital outflows due to the reform and, using the theoretical prediction, assess its impact using mathematical simulations.FindingsThe authors predict that the reform may cause severe credit constraints to SMEs which cannot pledge enough collateral in order to obtain credit. The most direct consequences are to reduce in the long run the amount of liquid assets available to Italian firms, and to reduce their aggregate investment in a more than proportional way, due to access to credit restrictions. However, it will not increase the cost of intermediated finance, ceteris paribus.Practical implicationsThe fact that the reform restricts access to credit, but does not increase the cost of debt, has important policy consequences, as public interventions subsidizing credit through a constant cost of debt may be ineffective.Originality/valueWhile the topic has been analyzed in several respects (e.g. workers' participation to the reform, cost of an access to credit subsidy, etc.), no other study proposed an integrated view of these effects with a rigorous micro‐economic approach.

Abstract. We examined (peak-to-background flux ratio p/b > 20) energetic electron bursts in the presence of VLF activity, as observed from the DEMETER satellite at low altitudes (~700 km). Our statistical analysis of measurements during two 6-month periods suggests that: (a) the powerful transmitter NWC causes the strongest effects on the inner radiation belts in comparison with other ground-based VLF transmitters, (b) the NWC transmitter was responsible for only ~1.5 % of total electron bursts examined during the 6-month period (1 July 2008 to 31 December 2008), (c) VLF transmitter-related electron bursts are accompanied by the presence of a narrow band emission centered at the radiating frequency emission, whereas the earthquake-related electron bursts are accompanied by the presence of broadband emissions from a few kHz to >20 KHz, (d) daytime events are less preferable than nighttime events, but this asymmetry was found to be less evident when the powerful transmitter NWC was turned off and (d) seismic activity most probably dominated the electromagnetic interactions producing the electron precipitation at middle latitudes. The results of this study support the proposal that the detection of radiation belt electron precipitation, besides other kinds of studies, is a useful tool for earthquake prediction research.

Objective: The study focuses on potential compatibility relationships when simple lever tools are used. Background: Spatial compatibility between stimuli and responses determines performance. However, many tasks require the use of simple tools, such as levers that transform hand movements into tool movements. We explore with such a tool whether and how the correspondence or noncorrespondence between stimulus-side and hand movement (stimulus-response compatibility), between stimulus-side and tool-effect movement (stimulus-effect compatibility), and/or between hand movement and tool-effect movement (response-effect compatibility) affects performance. Method:U-shaped and inverted-U-shaped levers were used as tools, allowing us to examine the contribution of each compatibility relationship to response times and errors without any confounds and omissions. Results: Responding was delayed and error prone when the hand movement and the movement of the effect point of the tool did not correspond. Effects of stimulus-response compatibility and stimulus-effect compatibility were observed only when the hand movement direction remained untransformed in the tool-effect movement. Conclusion: The results point out that the inversion or noninversion of tool-effect movements plays an underlying role when handling a tool. Application: Potential applications of this research include the prediction and possibly manipulation of unwanted behavioral tendencies in laparoscopic surgery and other lever movements.

PurposeThis study aims to investigate self‐monitoring as a moderator of the relationship between organizational position and perceptions of individual effort.Design/methodology/approach.A total of 133 students were randomly assigned to organizations of 12‐15 members. Each organization completed three projects in 14 weeks. Each student served in one position: management or non‐management. Participants also rated the effort of organizational members and then responded to items on the Self‐monitoring Scale.FindingsPersons in management were rated as giving more effort than persons in non‐management. Self‐monitoring moderated the relationship between organizational position and perceptions of effort. Organizational members perceived high self‐monitors (HSMs) in management as giving more effort than HSMs in non‐management. In contrast, there was no difference in perceived effort of low self‐monitors (LSMs) across positions.Research limitations/implicationsBy using students instead of actual employees working in project teams, the results may not generalize to all organizations. Because job performance is a multidimensional construct, findings may have limited application to very specific aspects of contextual performance.Originality/valueThese findings provide support for self‐monitoring as a moderator of organizational position and performance. This helps to reconcile debate about predicting behavior for cross‐situationally consistent LSMs and cross‐situationally variable HSMs. Implications for performance appraisals and differential prediction of criteria are discussed.

This paper formalizes in a fully-rational model the popular idea that politicians perceive an electoral cost in adopting costly reforms with future benefits and reconciles it with the evidence that reformist governments are not punished by voters. To do so, it proposes a model of elections where political ability is ex-ante unknown and investment in reforms is unobservable. On the one hand, elections improve accountability and allow to keep well-performing incumbents. On the other, politicians make too little reforms in an attempt to signal high ability and increase their reappointment probability. Although in a rational expectation equilibrium voters cannot be fooled and hence reelection does not depend on reforms, the strategy of underinvesting in reforms is nonetheless sustained by out-of-equilibrium beliefs. Contrary to the conventional wisdom, uncertainty makes reforms more politically viable and may, under some conditions, increase social welfare. The model is then used to study how political rewards can be set so as to maximize social welfare and the desirability of imposing a one-term limit to governments. The predictions of this theory are consistent with a number of empirical regularities on the determinants of reforms and reelection. They are also consistent with a new stylized fact documented in this paper: economic uncertainty is associated to more reforms in a panel of 20 OECD countries.

JEL classification: Z1; D03; L82. ; This paper develops a model of cultural transmission where television plays a central role for socialization. Parents split their free time between educating their children which is costly and watching TV which though entertaining might socialize the children to the wrong trait. The free to air television industry maximizes advertisement revenue. We show that TV watching is increasing in cultural coverage, cost of education, TV's entertainment value and decreasing in the perceived cultural distance between the two traits. A monopolistic television industry captures all TV watching by both groups if the perceived cultural distance between groups is small relative to the TV's entertainment value. Otherwise, more coverage will be given to the most profitable group where profitability increases in group size, advertisement sensitivity and perceived cultural distance. This leads to two possible steady states where one group is larger but both groups survive in the long run. Competition in the media industry might lead to cultural extinction but only if one group is very insensitive to advertisement and not radical enough not to watch TV. We briefly discuss the existing evidence for the empirical predictions of the model. ; Financial support from CICYT project number ECO2009-12695 and from the government of Catalonia. ; Peer reviewed

The current regulations governing production of biofuels in the European Union require that they have to mitigate climate change, by producing >35% less greenhouse gases (GHG) than fossil fuels. There is a risk that this may not be achievable, since land use for crop production inevitably emits the potent GHG nitrous oxide (N2O), due to nitrogen fertilisation and cycling in the environment. We analyse first-generation biofuel production on agricultural land and conclude that efficient agricultural crop production resulting in a good harvest and low N2O emission can fulfil the EU standard, and is possible under certain conditions for the Swedish agricultural and bioethanol production systems. However, in years having low crop yields, and where cropping is on organic soils, total GHG emissions per unit of fuel produced can be even higher than those released by burning of fossil fuels. In general, the N2O emission size in Sweden and elsewhere in northern Europe is such that there is a >50% chance that the 35% saving requirement will not be met. Thus ecosystem N2O emissions have to be convincingly assessed. Here we compare Swedish emission data with values estimated by means of statistical models and by a global, top-down, approach; the measurements and the predictions often show higher values that would fail to meet the EU standard and thus prevent biofuel production development.

Objectives: Mainstream environmental assessment (EA) methodologies often inadequately address health, social and cultural impacts of concern for Canadian indigenous communities affected by industrialization. Our objective is to present a holistic, culturally-appropriate framework for the selection of indigenous health indicators for baseline health assessment, impact prediction, or monitoring of impacts over time. Methods: We used a critical population health approach to explore the determinants of health and health inequities in indigenous communities and conceptualize the pathways by which industrialization affects these determinants. We integrated and extended key elements from three indigenous health frameworks into a new holistic model for the selection of indigenous EA indicators. Results: The holistic model conceptualizes individual and community determinants of health within external social, economic and political contexts and thus provides a comprehensive framework for selecting indicators of indigenous health. Indigenous health is the product of interactions among multiple determinants of health and contexts. Potential applications are discussed using case study examples involving indigenous communities affected by industrialization. Conclusion: Industrialization can worsen indigenous health inequities by perpetuating the health, social and cultural impacts of historic environmental dispossession. To mitigate impacts, EA should explicitly recognize linkages between environmental dispossession and the determinants of health and health inequities and meaningfully involve indigenous communities in the process.

Zoonotic disease surveillance is typically triggered after animal pathogens have already infected humans. Are there ways to identify high-risk viruses before they emerge in humans? If so, then how and where can identifications be made and by what methods? These were the fundamental questions driving a workshop to examine the future of predictive surveillance for viruses that might jump from animals to infect humans. Virologists, ecologists and computational biologists from academia, federal government and non-governmental organizations discussed opportunities as well as obstacles to the prediction of species jumps using genetic and ecological data from viruses and their hosts, vectors and reservoirs. This workshop marked an important first step towards envisioning both scientific and organizational frameworks for this future capability. Canine parvoviruses as well as seasonal H3N2 and pandemic H1N1 influenza viruses are discussed as exemplars that suggest what to look for in anticipating species jumps. To answer the question of where to look, prospects for discovering emerging viruses among wildlife, bats, rodents, arthropod vectors and occupationally exposed humans are discussed. Finally, opportunities and obstacles are identified and accompanied by suggestions for how to look for species jumps. Taken together, these findings constitute the beginnings of a conceptual framework for achieving a virus surveillance capability that could predict future species jumps.

A cross-sectional study was conducted at Sungai Lembing (SL) and Bukit Ubi (BU), Kuantan, Malaysia. The main objectives of this epidemiological study were to determine the aluminum concentration in drinking water, to compare with the government standard and to perform health risk assessment prediction among respondents from these two residential areas. A total of 100 respondents were selected from the study areas based on a few inclusive and exclusive criteria. Two duplicates of treated water samples were taken from each respondent's house using a 200 mL high-density polyethylene (HDPE) bottle and 0.4 mL (69%) pure concentrated nitric acid added as preservative. Aluminum concentrations were analyzed using Lambda 25 UV/V spectrophotometer. The result showed that the mean concentration of aluminum in drinking water from SL was 0.11 ± 0.0634 mg/L and 0.12 ± 0.0462 mg/L for BU. The mean value of Chronic Daily Intake (CDI) in SL (0.0035 ± 0.0028 mg/kg/day) was lower compared to BU (0.0037 ± 0.0021 mg/kg/day). The Hazard Index (HI) calculation showed all respondents had HI less than 1. In conclusion, there was unlikely potential for adverse health effects from aluminum intake in drinking water. However, it was necessary for some action to be taken in order to reduce aluminum levels found in drinking water in both locations.

International audience We devise an experiment to explore the effect of different degrees of bargaining power on the design and the selection of contracts in a hidden-information context. In our benchmark case, each principal is matched with one agent of unknown type. In our second treatment, a principal can select one of three agents, while in a third treatment an agent may choose between the contract menus offered by two principals. We first show theoretically how different ratios of principals and agents affect outcomes and efficiency. Informational asymmetries generate inefficiency. In an environment where principals compete against each other to hire agents, these inefficiencies may disappear, but they are insensitive to the number of principals. In contrast, when agents compete to be hired, efficiency improves dramatically, and it increases in the relative number of agents because competition reduces the agents' informational monopoly power. However, this environment also generates a high inequality level and is characterized by multiple equilibria. In general, there is a fairly high degree of correspondence between the theoretical predictions and the contract menus actually chosen in each treatment. There is, however, a tendency to choose more 'generous' (and more efficient) contract menus over time. We find that competition leads to a substantially higher probability of trade, and that, overall, competition between agents generates the most efficient outcomes.

This paper offers new insights on the price setting behaviour of German retail firms using a novel dataset that consists of a large panel of monthly business surveys from 1991-2006. The firm-level data allows matching changes in firms' prices to several other firm-characteristics. Moreover, information on price expectations allow analyzing the determinants of price updating. Using univariate and bivariate ordered probit specifications, empirical menu cost models are estimated relating the probability of price adjustment and price updating, respectively, to both time- and state- dependent variables. First, results suggest an important role for state-dependence; changes in the macroeconomic and institutional environment as well as firm-specific factors are significantly related to the timing of price adjustment. These findings imply that price setting models should endogenize the timing of price adjustment in order to generate realistic predictions concerning the transmission of monetary policy. Second, an analysis of price expectations yields similar results providing evidence in favour of state-dependent sticky plan models. Third, intermediate input cost changes are among the most important determinants of price adjustment suggesting that pricing models should explicitly incorporate price setting at different production stages. However, the results show that adjustment to input cost changes takes time indicating "additional stickiness" at the last stage of processing.