579 research outputs found
Kaon and production vs Participants in Nuclear Collisions
Data on kaon and production in nuclear collisions as a function of
centrality are analysed both at AGS and SPS energy range. We compare the
results of several experiments, looking for common trend in `participant
scaling' of production yields. We find a smooth description of scaled kaon and
yields as a function of participant density. We also show a participant
density dependence of kaons and produced in the forward hemisphere for
proton-nucleus collisions.Comment: Proceedings of the International Conference on Strangeness in Quark
Matter, 20-25 July 2000, Berkeley, CA. To appear in Journal of Physics G:
Nuclear and Particle Physic
Charm quenching in heavy-ion collisions at the LHC
D-meson suppression in Pb-Pb collisions at the LHC due to charm quark
in-medium energy loss is estimated within a model that describes the available
quenching measurements at RHIC. The result is compared to that previously
published by the author. The expected sensitivity of the ALICE experiment for
studying charm energy loss via fully-reconstructed D^0-meson decays is also
presented.Comment: 8 pages, 3 figures. To appear in the proceedings of Hot Quarks 2004:
Workshop for Young Scientists on the Physics of Ultrarelativistic
Nucleus-Nucleus Collisions, Taos Valley, New Mexico, 18-24 July 2004.
Submitted to J. Phys.
Complementarity in the adoption of traceability of beef cattle in Brazil.
Complementarity is an interesting approach to explain technology adoption. Taking account the other activities the farm performs in its production strategy can help understanding the decision on the adoption of new agricultural technology. This paper aims to evidence the existence of synergic effect resulting from the joint adoption of feedlot and traceability certification of beef cattle in Brazil. A sample of 84 beef cattle farms provided data to test hypotheses by using an OLS regression model. A measure of performance ? revenue ? is regressed on variables representing both isolated and joint adoption of capital-intensive production system and traceability. The results suggest the existence of synergic effect when joint adoption takes place. Joint adoption is influenced by a set of management practices, such as forward contracts, training of employees and zootechnical performance control, which are shared by both capital-intensive production systems and traceability
Hard probes in heavy ion collisions at the LHC: heavy flavour physics
We present the results from the heavy quarks and quarkonia working group.
This report gives benchmark heavy quark and quarkonium cross sections for
and collisions at the LHC against which the rates can be compared in
the study of the quark-gluon plasma. We also provide an assessment of the
theoretical uncertainties in these benchmarks. We then discuss some of the cold
matter effects on quarkonia production, including nuclear absorption,
scattering by produced hadrons, and energy loss in the medium. Hot matter
effects that could reduce the observed quarkonium rates such as color screening
and thermal activation are then discussed. Possible quarkonium enhancement
through coalescence of uncorrelated heavy quarks and antiquarks is also
described. Finally, we discuss the capabilities of the LHC detectors to measure
heavy quarks and quarkonia as well as the Monte Carlo generators used in the
data analysis.Comment: 126 pages Latex; 96 figures included. Subgroup report, to appear in
the CERN Yellow Book of the workshop: Hard Probes in Heavy Ion Collisions at
the LHC. See also http://a.home.cern.ch/f/frixione/www/hvq.html for a version
with better quality for a few plot
Correlations of Heavy Quarks Produced at Large Hadron Collider
We study the correlations of heavy quarks produced in relativistic heavy ion
collisions and find them to be quite sensitive to the effects of the medium and
the production mechanisms. In order to put this on a quantitative footing, as a
first step, we analyze the azimuthal, transverse momentum, and rapidity
correlations of heavy quark-anti quark () pairs in
collisions at (). This sets the stage for the
identification and study of medium modification of similar correlations in
relativistic collision of heavy nuclei at the Large Hadron Collider. Next we
study the additional production of charm quarks in heavy ion collisions due to
multiple scatterings, {\it viz.}, jet-jet collisions, jet-thermal collisions,
and thermal interactions. We find that these give rise to azimuthal
correlations which are quite different from those arising from prompt initial
production at leading order and at next to leading order.Comment: 26 pages, 15 figures. Three new figures added, comparison to
experimental data included, abstract and discussion expande
On the Development of Health-Based Ventilation Guidelines : Principles and Framework
This paper summarizes the results of HealthVent project. It had an aim to develop health-based ventilation guidelines and through this process contribute to advance indoor air quality (IAQ) policies and guidelines. A framework that allows determining ventilation requirements in public and residential buildings based on the health requirements is proposed. The framework is based on three principles: 1. Criteria for permissible concentrations of specific air pollutants set by health authorities have to be respected; 2. Ventilation must be preceded by source control strategies that have been duly adopted to improve IAQ; 3. Base ventilation must always be secured to remove occupant emissions (bio-effluents). The air quality guidelines defined by the World Health Organization (WHO) outside air are used as the reference for determining permissible levels of the indoor air pollutants based on the principle that there is only one air. It is proposed that base ventilation should be set at 4 L/s per person; higher rates are to be used only if WHO guidelines are not followed. Implementation of the framework requires technical guidelines, directives and other legislation. Studies are also needed to examine the effectiveness of the approach and to validate its use. It is estimated that implementing the framework would bring considerable reduction in the burden of disease associated with inadequate IAQ
A Comment on Conical Flow Induced by Heavy-Quark Jets
The suppression of high transverse momentum particles, recently discovered at
RHIC, is commonly interpreted as due to parton energy loss. In high energy
nuclear collisions, QCD jets would deposit a large fraction of their energy and
into the produced matter. The question of how this energy is degraded and
whether we can use this phenomenon to probe the properties of the produced
matter is now under active discussion. It has been proposed that if this
matter, which is now being referred to as a {\em strongly coupled Quark-Gluon
Plasma} (sQGP), may behave as a liquid with a very small viscosity.
In this case, a very specific collective excitation should be produced,
called the ``conical flow'', similar e.g. to the sonic booms generated by the
shock waves produced by supersonic planes. The RHIC experiments seem indeed to
be obtaining some indication that the production of particles emitted opposite
to a high- jet may actually be peaked away from the quenched jet
direction, at an angle roughly consistent with the direction expected in case a
shock wave is produced (i.e. orthogonal to the Mach cone). In this note we
speculate that for tagged heavy-quark jets one may observe a shrinkage of the
Mach cone at moderate . The experimental observation of such an effect
would be a very good test for the validity of the whole picture currently
emerging from the study of partonic matter in nuclear collisions
Preditores da adoção de sistemas de integração lavoura-pecuária em São Paulo e o papel dos intermediários da inovação.
Este artigo tem como objetivo propor um modelo analítico para identificar preditores de regiões propensas à difusão de tecnologia de processo, bem como identificar e descrever funções de apoio à inovação. Utilizou-se as abordagens teóricas de difusão de inovações e de intermediários da inovação. Analisou-se a adoção de sistemas de integração lavoura-pecuária (ILP) no estado de São Paulo. O método proposto consistiu de (i) revisão da literatura sobre adoção e difusão de inovações e intermediários da inovação, (ii) um survey para identificar fatores que influenciam a adoção de ILP e (iii) a comparação de dois municípios com elevada difusão de ILP com sua região de desenvolvimento rural (EDR). Foram utilizados dados censitários sobre aspectos organizacionais e institucionais da região e características das propriedades rurais. Demonstrou-se que os preditores são: tamanho da propriedade; atividade pecuária e tipo de manejo predominantes; participação em cooperativa, sindicato rural e associação de produtores; além do acesso a serviços de extensão, seguro e crédito rural. Identificou-se que instituições e organizações atuam como intermediários da inovação, facilitando a interação e conexão entre os atores e promovendo serviços essenciais de apoio à adoção de tecnologias agrícolas
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