569 research outputs found
Precautionary Regulation in Europe and the United States: A Quantitative Comparison
Much attention has been addressed to the question of whether Europe or the United States adopts a more precautionary stance to the regulation of potential environmental, health, and safety risks. Some commentators suggest that Europe is more risk-averse and precautionary, whereas the US is seen as more risk-taking and optimistic about the prospects for new technology. Others suggest that the US is more precautionary because its regulatory process is more legalistic and adversarial, while Europe is more lax and corporatist in its regulations. The flip-flop hypothesis claims that the US was more precautionary than Europe in the 1970s and early 1980s, and that Europe has become more precautionary since then. We examine the levels and trends in regulation of environmental, health, and safety risks since 1970. Unlike previous research, which has studied only a small set of prominent cases selected non-randomly, we develop a comprehensive list of almost 3,000 risks and code the relative stringency of regulation in Europe and the US for each of 100 risks randomly selected from that list for each year from 1970 through 2004. Our results suggest that: (a) averaging over risks, there is no significant difference in relative precaution over the period, (b) weakly consistent with the flip-flop hypothesis, there is some evidence of a modest shift toward greater relative precaution of European regulation since about 1990, although (c) there is a diversity of trends across risks, of which the most common is no change in relative precaution (including cases where Europe and the US are equally precautionary and where Europe or the US has been consistently more precautionary). The overall finding is of a mixed and diverse pattern of relative transatlantic precaution over the period
Whispering gallery modes in open quantum billiards
The poles of the S-matrix and the wave functions of open 2D quantum billiards
with convex boundary of different shape are calculated by the method of complex
scaling. Two leads are attached to the cavities. The conductance of the
cavities is calculated at energies with one, two and three open channels in
each lead. Bands of overlapping resonance states appear which are localized
along the convex boundary of the cavities and contribute coherently to the
conductance. These bands correspond to the whispering gallery modes appearing
in the classical calculations.Comment: 9 pages, 3 figures in jpg and gif forma
Time-resolved dynamics of electron wave packets in chaotic and regular quantum billiards with leads
We perform numerical studies of the wave packet propagation through open
quantum billiards whose classical counterparts exhibit regular and chaotic
dynamics. We show that for t less or similar to tau (tau being the Heisenberg
time), the features in the transmitted and reflected currents are directly
related to specific classical trajectories connecting the billiard leads. In
contrast, the long-time asymptotics of the wave packet dynamics is
qualitatively different for classical and quantum billiards. In particularly,
the decay of the quantum system obeys a power law that depends on the number of
decay channels, and is not sensitive to the nature of classical dynamics
(chaotic or regular).Comment: 5 pages, 4 figure
Atmospheric sulfur cycling in the southeastern Pacific – longitudinal distribution, vertical profile, and diel variability observed during VOCALS-REx
Dimethylsulfide (DMS) emitted from the ocean is a biogenic precursor gas for sulfur dioxide (SO<sub>2</sub>) and non-sea-salt sulfate aerosols (SO<sub>4</sub><sup>2&minus;</sup>). During the VAMOS-Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) in 2008, multiple instrumented platforms were deployed in the Southeastern Pacific (SEP) off the coast of Chile and Peru to study the linkage between aerosols and stratocumulus clouds. We present here observations from the NOAA Ship <i>Ronald H. Brown</i> and the NSF/NCAR C-130 aircraft along ~20° S from the coast (70° W) to a remote marine atmosphere (85° W). While SO<sub>4</sub><sup>2&minus;</sup> and SO<sub>2</sub> concentrations were distinctly elevated above background levels in the coastal marine boundary layer (MBL) due to anthropogenic influence (~800 and 80 pptv, respectively), their concentrations rapidly decreased west of 78° W (~100 and 25 pptv). In the remote region, entrainment from the free troposphere (FT) increased MBL SO<sub>2</sub> burden at a rate of 0.05 &plusmn; 0.02 μmoles m<sup>&minus;2</sup> day<sup>&minus;1</sup> and diluted MBL SO<sub>4</sub><sup>2</sup> burden at a rate of 0.5 &plusmn; 0.3 μmoles m<sup>&minus;2</sup> day<sup>&minus;1</sup>, while the sea-to-air DMS flux (3.8 &plusmn; 0.4 μmoles m<sup>&minus;2</sup> day<sup>&minus;1</sup>) remained the predominant source of sulfur mass to the MBL. In-cloud oxidation was found to be the most important mechanism for SO<sub>2</sub> removal and in situ SO<sub>4</sub><sup>2&minus;</sup> production. Surface SO<sub>4</sub><sup>2&minus;</sup> concentration in the remote MBL displayed pronounced diel variability, increasing rapidly in the first few hours after sunset and decaying for the rest of the day. We theorize that the increase in SO<sub>4</sub><sup>2&minus;</sup> was due to nighttime recoupling of the MBL that mixed down cloud-processed air, while decoupling and sporadic precipitation scavenging were responsible for the daytime decline in SO<sub>4</sub><sup>2&minus;</sup>
Conductance of Open Quantum Billiards and Classical Trajectories
We analyse the transport phenomena of 2D quantum billiards with convex
boundary of different shape. The quantum mechanical analysis is performed by
means of the poles of the S-matrix while the classical analysis is based on the
motion of a free particle inside the cavity along trajectories with a different
number of bounces at the boundary. The value of the conductance depends on the
manner the leads are attached to the cavity. The Fourier transform of the
transmission amplitudes is compared with the length of the classical paths.
There is good agreement between classical and quantum mechanical results when
the conductance is achieved mainly by special short-lived states such as
whispering gallery modes (WGM) and bouncing ball modes (BBM). In these cases,
also the localization of the wave functions agrees with the picture of the
classical paths. The S-matrix is calculated classically and compared with the
transmission coefficients of the quantum mechanical calculations for five modes
in each lead. The number of modes coupled to the special states is effectively
reduced.Comment: 19 pages, 6 figures (jpg), 2 table
Mapping an atlas of tissue-specific drosophila melanogaster metabolomes by high resolution mass spectrometry
Metabolomics can provide exciting insights into organismal function, but most work on simple models has focussed on the whole organism metabolome, so missing the contributions of individual tissues. Comprehensive metabolite profiles for ten tissues from adult Drosophila melanogaster were obtained here by two chromatographic methods, a hydrophilic interaction (HILIC) method for polar metabolites and a lipid profiling method also based on HILIC, in combination with an Orbitrap Exactive instrument. Two hundred and forty two polar metabolites were putatively identified in the various tissues, and 251 lipids were observed in positive ion mode and 61 in negative ion mode. Although many metabolites were detected in all tissues, every tissue showed characteristically abundant metabolites which could be rationalised against specific tissue functions. For example, the cuticle contained high levels of glutathione, reflecting a role in oxidative defence; the alimentary canal (like vertebrate gut) had high levels of acylcarnitines for fatty acid metabolism, and the head contained high levels of ether lipids. The male accessory gland uniquely contained decarboxylated S-adenosylmethionine. These data thus both provide valuable insights into tissue function, and a reference baseline, compatible with the FlyAtlas.org transcriptomic resource, for further metabolomic analysis of this important model organism, for example in the modelling of human inborn errors of metabolism, aging or metabolic imbalances such as diabetes
Possible changes to arable crop yields by 2050
By 2050, the world population is likely to be 9.1 billion, the CO2 concentration 550 ppm, the ozone concentration 60 ppb and the climate warmer by ca 2°C. In these conditions, what contribution can increased crop yield make to feeding the world
Punctuated equilibrium theory in Brazilian public policy: the case of Ceará
Este artigo faz uma análise do processo de decisão orçamental dos municípios do Estado do Ceará. Através deste estudo, procura-se perceber em que medida a distribuição dos orçamentos aos governos locais sofrem (ou não) variações. Já em um segundo momento, tenta-se depreender quais as receitas de cada um dos municípios (as variáveis independentes) que melhor descrevem e auxiliam a opção política de investimento local (esta será a variável dependente). Considerando o período de 2006 a 2010 e fazendo uso de um desenho de pesquisa de tipo transversal, conclui-se que nos governos locais do Ceará o investimento público apresenta períodos de estabilidade seguido por períodos de grande alteração dos orçamentos – confirmando a hipótese de pesquisa. Estas conclusões confirmam os pressupostos da teoria do equilíbrio pontuado. Conclui-se igualmente que o investimento público que vem sendo realizado é dependente das transferências que a União faz para os governos locais do Estado do Ceará e das receitas de capital. Face a estas condições, é pertinente equacionar até que nível e grau o endividamento pode ocorrer em virtude da escassez cada vez maior do financiamento público.This research aims to analyze the budget decision process in
Ceará municipalities in order to understand in which
way budget distributions change (or not) during the research period under consideration. This research also aims
to understand which revenues (the independent variables) of each municipality better expla
in the political choices
for local government investments (the dependent variable). Making use of data from 2006 to 2010 and using a
cross
-
sectional research design, the study concludes a stability in local government investments periods of stress
where su
ch investments have both positive and negative significant fluctuations
–
confirming our working
hypothesis. These results confirm punctuated Equilibrium Theory assumptions and also find that local government
public investment is dependent on money transfe
rs from the central government and also from capital revenues.
Thus, it is important to question to what degree public indebtedness should be allowed, due to a scarcity of public
fundsinfo:eu-repo/semantics/publishedVersio
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ENDF/B-VII.0 Data Testing for Three Fast Critical Assemblies
In this report we consider three fast critical assemblies, each assembly is dominated by a different nuclear fuel: Godiva (U235), Jezebel (Pu239) and Jezebel23 (U233) [1]. We first show the improvement in results when using the new ENDF/B-VII.0 data [2], rather than the older, now frozen, ENDF/B-VI.8 data [3]. We do this using what we call a one code/ multiple library approach, where results from one code (MCNP) are compared using two different data libraries (ENDF/B-VII.0 and VI.8). Next we show that MCNP results are not specific to this one code by using what we call a one data library/multiple code approach; for this purpose we invited many codes to submit results using the ENDF/B-VII.0 data; the most detailed results presented in this report compare MCNP and TART. The bottom line is that we have shown that using the new ENDF/B-VII.0 data library with a variety of transport codes, for the first time we are able to reproduce the expected K-eff values for all three assemblies to within the quoted accuracy of the models, namely 1.0 +/- 0.001. This is a BIG improvement compared to the results obtained using the older ENDF/B-VI.8 data library. Another important result of this study is that we have demonstrated that currently there are many computer codes that can accurately use the new ENDF/B-VII.0 data
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