130 research outputs found
QCD Effects in the Decays of TeV Black Holes
In models with ``large'' and/or warped extra dimensions, the
higher-dimensional Planck scale may be as low as a TeV. In that case black
holes with masses of a few TeV are expected to be produced copiously in
multi-TeV collisions, in particular at the LHC. These black holes decay through
Hawking radiation into typically O(20) Standard Model particles. Most of these
particles would be strongly interacting. Naively this would lead to a final
state containing 10 or so hadronic jets. However, it has been argued that the
density of strongly interacting particles would be so large that they
thermalize, forming a ``chromosphere'' rather than well-defined jets. In order
to investigate this, we perform a QCD simulation which includes parton-parton
scattering in addition to parton showering. We find the effects of parton
scattering to remain small for all cases we studied, leading to the conclusion
that the decays of black holes with masses within the reach of the LHC will not
lead to the formation of chromospheres.Comment: LaTeX with equation.sty (included), 26 pages, 4 figures. Added a few
references and one footnot
GESTÃO AMBIENTAL EMPRESARIAL E COMPETITIVIDADE DE SISTEMAS AGROINDUSTRIAIS
A preocupação com o meio ambiente por parte da sociedade mundial vem ganhando força a cada dia, levando as empresas a dar uma maior atenção à dimensão ambiental de suas atividades econômicas. Cada vez mais a classe empresarial visualiza a importância da gestão ambiental como fator de competitividade e sustentabilidade de seus negócios. Procurando avançar nesse sentido, objetiva-se nesse trabalho analisar, através de uma revisão teórica, como estratégias de gestão ambiental, através de seus benefÃcios, podem se conformar como um fator de competitividade para empresas inseridas no agronegócio e para sistemas agroindustriais. O trabalho de revisão aborda a idéia do enfoque sistêmico, necessária para estudos referentes ao agronegócio, conceitos e definições de competitividade e suas especificidades para uma cadeia ou um sistema agroindustrial, e tipos de estratégias ambientais e os seus potenciais benefÃcios para as empresas. Por fim, procura-se caracterizar as particularidades de aplicação da gestão ambiental para um sistema ou cadeia agroindustrial. Como resultados são apontadas as evidências teóricas que levam à convergência dos potenciais benefÃcios da gestão ambiental empresarial com alguns conceitos e pontos de vista sobre a competitividade no agronegócio.----------------------------------------------The concern with the environment on the part of the world society is winning force every day, taking the companies to give larger attention to the environmental dimension of their economical activities. More and more the business class visualizes the importance of the environmental management as factor of competitiveness and sustainability of their businesses. Trying to move forward in that sense, aimed in this work to analyze, through a theoretical revision, as strategies of environmental management and their benefits can conform as a factor of competitiveness for companies inserted in the agribusiness and for agrifood systems. The revision work involves the idea of the systems approach, necessary for studies regarding the agribusiness, concepts and definitions of competitiveness and their specificities for a chain or an agrifood system, concepts of environmental management, types of environmental strategies and their potentials benefits for the companies. As results are pointed the theoretical evidences that take the convergence of the potentials benefits of the environmental management with some concepts and point of view about the competitiveness in the agibusiness.Gestão Ambiental, competitividade, agronegócio, Environmental management, competitiveness, agribusiness, Agribusiness,
Tillage-induced spatial distribution of surface crusts on a sandy paleustult from Togo
The spatial distribution of crusts in coarse-textured soils and the processes affecting it are poorly documented, despite the potential impact of crusts on water infiltration. This study addresses the influence of tillage-induced microrelief on the morphology and spatial distribution of surface crusts in an oxic paleustult from southern Togo (West Africa). Replicate 1 m2 plots were exposed to 217 mm of natural rainfall during a 6-wk period, during which the surface topography was measured three times. Subsequently, 24 undisturbed crust samples were used for micromorphological analysis. The crusts exhibited a range of morphologies but were nevertheless adequately mapped and characterized according to two main types. Type 1 crusts (= runoff crusts) showed several superposed clay bands, 100 to 500 mm thick, buried within a micromass-depleted sand layer lesser or equal to 12 mm thick. Type 2 crusts (= erosion crusts) had an exposed clay band a few tenths of a millimeter thick. The spatial distribution of crusts at the time of sampling appeared better correlated with the initial than with the final microtopography of the plots. These findings suggest that crust distribution should be regarded as history dependent and that erosion and deposition processes largely governed the development of the crusts. This latter aspect is in agreement with the recent crust genesis model of Valentin and Bresson, as is the fact that clay bands in our plots were laterally continuous at all observational scales lesser or equal to 0.1 m. Other mechanisms proposed in the literature for the developement of clay bands did not seem able to account adequately for the observed pattern. (Résumé d'auteur
Konsum, ökonomische Ungleichheit und sozialer Status
Zwischen der Würde eines Menschen und seinem sozialen Status besteht ein
enger Zusammenhang, der sich über Armut und Reichtum vermittelt. So lautet
unsere Grundthese in diesem Aufsatz, die wir in drei Schritten darlegen. In
einem ersten Schritt klären wir die Begriffe der Würde, der Armut, des Reichtums
und des sozialen Status. In einem zweiten Schritt zeigen wir auf phänomenologische
Weise, wie stark Konsumverhalten von den ökonomischen
Verhältnissen abhängt und wie wichtig Konsum für den sozialen Status ist. In
einem dritten Schritt führen wir die beiden ersten Teile zusammen und argumentieren
für den Zusammenhang von Würde, Ungleichheit und Status
Calculating the mass fraction of primordial black holes
We reinspect the calculation for the mass fraction of primordial black holes (PBHs) which are formed from primordial perturbations, finding that performing the calculation using the comoving curvature perturbation c in the standard way vastly overestimates the number of PBHs, by many orders of magnitude. This is because PBHs form shortly after horizon entry, meaning modes significantly larger than the PBH are unobservable and should not affect whether a PBH forms or not - this important effect is not taken into account by smoothing the distribution in the standard fashion. We discuss alternative methods and argue that the density contrast, Δ, should be used instead as super-horizon modes are damped by a factor k2. We make a comparison between using a Press-Schechter approach and peaks theory, finding that the two are in close agreement in the region of interest. We also investigate the effect of varying the spectral index, and the running of the spectral index, on the abundance of primordial black holes
Open Science and the Library – Fields of Action and Occupational Profile
Eine durch die Digitalisierung veränderte und auf Open Science ausgerichtete Wissenschaftspraxis benötigt angepasste Infrastrukturen und Services. Daraus ergeben sich verschiedene neue oder veränderte Aktionsfelder für wissenschaftliche Bibliotheken und Infrastruktureinrichtungen. Zu nennen sind zum Beispiel die nicht-textuellen Materialien wie Forschungsdaten, AV-Medien oder Software und die Umsetzung der FAIR-Prinzipien. Hinzu kommen neue Aufgaben im Bereich der Forschungsinformationen, zum Beispiel in der Unterstützung institutioneller Forschungsinformationssysteme, die Gestaltung von Open Access, die Unterstützung kollaborativen wissenschaftlichen Arbeitens sowie die Schaffung von offenen Infrastrukturen. In diesem Artikel werden diese Felder kurz vorgestellt und sich daraus abzeichnende Anforderungen an das bibliothekarische Berufsbild skizziert.A scientific practice that has been changed by digitalisation and is oriented towards open science requires adapted infrastructures and services. This results in various new or changed fields of action for scientific libraries and infrastructure facilities. Examples include non-textual materials such as research data, audiovisual media or software, and the implementation of FAIR principles. In addition, there are new tasks in the field of research information, for example supporting institutional research information systems, shaping Open Access activities, the support of collaborative scientific work and the creation of open infrastructures. This article briefly presents these fields and outlines the resulting requirements for the library profession
Tracer Survey in the Cape Verde Region Traceraufnahme in der Kapverdenregion Cruise No. 10, Leg 1 October 31 – December 06, 2008 Ponta Delgada (Portugal) – Mindelo (Cape Verde Islands)
The research cruise MSM10/1 was extremely successful. All programs were able to collect high quality data and the anticipated goals of the expedition were fully met. We have been able to carry out the first comprehensive survey of a tracer release in the Guinea Upwelling region (GUTRE) roughly seven month after the tracer was released at 8°N 23°W in April 2008. We have estimated that a total of 40% of the tracer was found during this cruise. While the horizontal spreading and mixing was larger than anticipated, the vertical extent of the tracer found was small. The low vertical tracer spreading rate estimates are supported by the micro structure profile data. The extensive survey of the upper 1000m of the oxygen minimum zone (OMZ) allowed comparing our sections with several previous surveys. We found that the lowest oxygen values in the core of the OMZ have dropped at record low values below 40 μmol/kg. The preliminary findings from the trace metal work focused on Fe ligand measurements shows a slight higher excess ligand concentration in the surface (50m) for three stations. The two other stations show a slight decrease at this depth. A large number of biochemical samples were taken and were analyzed in Kiel for DNA and RNA diversity. The tracer release experiment provided an ideal environment for repeated biochemical sampling in the same water mass
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