978 resultados para Ma Twan Lin.
Resumo:
This paper evaluates the current status of global modeling of the organic aerosol (OA) in the troposphere and analyzes the differences between models as well as between models and observations. Thirty-one global chemistry transport models (CTMs) and general circulation models (GCMs) have participated in this intercomparison, in the framework of AeroCom phase II. The simulation of OA varies greatly between models in terms of the magnitude of primary emissions, secondary OA (SOA) formation, the number of OA species used (2 to 62), the complexity of OA parameterizations (gas-particle partitioning, chemical aging, multiphase chemistry, aerosol microphysics), and the OA physical, chemical and optical properties. The diversity of the global OA simulation results has increased since earlier AeroCom experiments, mainly due to the increasing complexity of the SOA parameterization in models, and the implementation of new, highly uncertain, OA sources. Diversity of over one order of magnitude exists in the modeled vertical distribution of OA concentrations that deserves a dedicated future study. Furthermore, although the OA / OC ratio depends on OA sources and atmospheric processing, and is important for model evaluation against OA and OC observations, it is resolved only by a few global models. The median global primary OA (POA) source strength is 56 Tg a−1 (range 34–144 Tg a−1) and the median SOA source strength (natural and anthropogenic) is 19 Tg a−1 (range 13–121 Tg a−1). Among the models that take into account the semi-volatile SOA nature, the median source is calculated to be 51 Tg a−1 (range 16–121 Tg a−1), much larger than the median value of the models that calculate SOA in a more simplistic way (19 Tg a−1; range 13–20 Tg a−1, with one model at 37 Tg a−1). The median atmospheric burden of OA is 1.4 Tg (24 models in the range of 0.6–2.0 Tg and 4 between 2.0 and 3.8 Tg), with a median OA lifetime of 5.4 days (range 3.8–9.6 days). In models that reported both OA and sulfate burdens, the median value of the OA/sulfate burden ratio is calculated to be 0.77; 13 models calculate a ratio lower than 1, and 9 models higher than 1. For 26 models that reported OA deposition fluxes, the median wet removal is 70 Tg a−1 (range 28–209 Tg a−1), which is on average 85% of the total OA deposition. Fine aerosol organic carbon (OC) and OA observations from continuous monitoring networks and individual field campaigns have been used for model evaluation. At urban locations, the model–observation comparison indicates missing knowledge on anthropogenic OA sources, both strength and seasonality. The combined model–measurements analysis suggests the existence of increased OA levels during summer due to biogenic SOA formation over large areas of the USA that can be of the same order of magnitude as the POA, even at urban locations, and contribute to the measured urban seasonal pattern. Global models are able to simulate the high secondary character of OA observed in the atmosphere as a result of SOA formation and POA aging, although the amount of OA present in the atmosphere remains largely underestimated, with a mean normalized bias (MNB) equal to −0.62 (−0.51) based on the comparison against OC (OA) urban data of all models at the surface, −0.15 (+0.51) when compared with remote measurements, and −0.30 for marine locations with OC data. The mean temporal correlations across all stations are low when compared with OC (OA) measurements: 0.47 (0.52) for urban stations, 0.39 (0.37) for remote stations, and 0.25 for marine stations with OC data. The combination of high (negative) MNB and higher correlation at urban stations when compared with the low MNB and lower correlation at remote sites suggests that knowledge about the processes that govern aerosol processing, transport and removal, on top of their sources, is important at the remote stations. There is no clear change in model skill with increasing model complexity with regard to OC or OA mass concentration. However, the complexity is needed in models in order to distinguish between anthropogenic and natural OA as needed for climate mitigation, and to calculate the impact of OA on climate accurately.
Resumo:
This chapter is a modest attempt to investigate how MA TEFL programmes in Iran are changing in a globalised world. Our previous research in this area (Hasrati & Tavakoli, in print; Tavakoli & Hasrati, in preparation) has shown how MAs in English Language Teaching programmes are developing in Anglophone countries, but little or no research has been conducted to study changes in MA TEFL programmes in Iran. In what follows, we will first introduce MA TEFL programmes in Iran, before presenting and discussing different definitions of globalisation. We will then explain how we collected the data for this study and report our findings, making comparisons with the other contexts when appropriate. We will conclude by elaborating on possible extensions of this study in similar contexts.
Resumo:
Aimed at reducing deficiencies in representing the Madden-Julian oscillation (MJO) in general circulation models (GCMs), a global model evaluation project on vertical structure and physical processes of the MJO was coordinated. In this paper, results from the climate simulation component of this project are reported. It is shown that the MJO remains a great challenge in these latest generation GCMs. The systematic eastward propagation of the MJO is only well simulated in about one-fourth of the total participating models. The observed vertical westward tilt with altitude of the MJO is well simulated in good MJO models, but not in the poor ones. Damped Kelvin wave responses to the east of convection in the lower troposphere could be responsible for the missing MJO preconditioning process in these poor MJO models. Several process-oriented diagnostics were conducted to discriminate key processes for realistic MJO simulations. While large-scale rainfall partition and low-level mean zonal winds over the Indo-Pacific in a model are not found to be closely associated with its MJO skill, two metrics, including the low-level relative humidity difference between high and low rain events and seasonal mean gross moist stability, exhibit statistically significant correlations with the MJO performance. It is further indicated that increased cloud-radiative feedback tends to be associated with reduced amplitude of intraseasonal variability, which is incompatible with the radiative instability theory previously proposed for the MJO. Results in this study confirm that inclusion of air-sea interaction can lead to significant improvement in simulating the MJO.
Resumo:
In an attempt to improve our understanding of the Paleoproterozoic geodynamic evolution, a paleomagnetic study was performed on 10 sites of acid volcanic rocks of the Colider Suite, southwestern Amazonian Craton. These rocks have a well-dated zircon U-Pb mean age of 1789 +/- 7 Ma. Alternating field and thermal demagnetization revealed northern (southern) directions with moderate to high upward (downward) inclinations. Rock magnetism experiments and magnetic mineralogy show that this characteristic magnetization is carried by Ti-poor magnetite or by hematite that replaces magnetite by late-magmatic cleuteric alteration. Both magnetite and hematite carry the same characteristic component. The mean direction (Dm = 183.0 degrees, Im = 53.5 degrees, N = 10, alpha(95) = 9.8 degrees, K = 25.2) yielded a paleomagnetic pole located at 298.8 degrees E, 63.3 degrees S (alpha(95) = 10.2 degrees, K = 23.6), which is classified with a quality factor Q = 5. Paleogeographic reconstructions using this pole and other reliable Paleoproterozoic poles suggest that Laurentia, Baltica, North China Craton and Amazonian Craton were located in laterally contiguous positions forming a large continental mass at 1790 Ma ago. This is reinforced by geological evidence which support the existence of the supercontinent Columbia in Paleoproterozoic times. (C) 2008 Elsevier B.V. All rights reserved.
Resumo:
We present measurements of the charge balance function, from the charged particles, for diverse pseudorapidity and transverse momentum ranges in Au + Au collisions at root S(NN) = 200 GeV using the STAR detector at RHIC. We observe that the balance function is boost-invariant within the pseudorapidity coverage vertical bar-1.3, 1.3 vertical bar. The balance function properly scaled by the width of the observed pseudorapidity window does not depend on the position or size of the pseudorapidity window. This scaling property also holds for particles in different transverse momentum ranges. In addition, we find that the width of the balance function decreases monotonically with increasing transverse momentum for all centrality classes. (c) 2010 Elsevier B.V. All rights reserved.
Resumo:
Nuclear collisions recreate conditions in the universe microseconds after the Big Bang. Only a very small fraction of the emitted fragments are light nuclei, but these states are of fundamental interest. We report the observation of antihypertritons-comprising an antiproton, an antineutron, and an antilambda hyperon-produced by colliding gold nuclei at high energy. Our analysis yields 70 +/- 17 antihypertritons (3/Lambda(H) over bar) and 157 +/- 30 hypertritons ((3)(Lambda)H). The measured yields of (3)(Lambda)H (3/Lambda(H) over bar) and (3)He ((3)(He) over bar) are similar, suggesting an equilibrium in coordinate and momentum space populations of up, down, and strange quarks and antiquarks, unlike the pattern observed at lower collision energies. The production and properties of antinuclei, and of nuclei containing strange quarks, have implications spanning nuclear and particle physics, astrophysics, and cosmology.
Resumo:
We present results on the system size dependence of high transverse momentum di-hadron correlations at root s(NN) = 200 GeV as measured by STAR at RHIC. Measurements in d + Au, Cu + Cu and Au + Au collisions reveal similar jet-like near-side correlation yields (correlations at small angular separation Delta phi similar to 0, Delta eta similar to 0) for all systems and centralities. Previous measurements have shown Chat the away-side (Delta phi similar to pi) yield is suppressed in heavy-ion collisions. We present measurements of the away-side Suppression as a function of transverse momentum and centrality in Cu + Cu and Au + Au collisions. The suppression is found to be similar in Cu + Cu and An + An collisions at a similar number of participants. The results are compared to theoretical calculations based on the patron quenching model and the modified fragmentation model. The observed differences between data and theory indicate that the correlated yields presented here will further constrain dynamic energy loss models and provide information about the dynamic density profile in heavy-ion collisions. (C) 2009 Elsevier B.V. All rights reserved.
Resumo:
We present the multiplicity and pseudorapidity distributions of photons produced in Au + Au and Cu + Cu collisions at root(s)NN = 62.4 and 200 GeV. The photons are measured in the region -3.7 < eta < -2.3 using the photon Multiplicity detector in the STAR experiment at RHIC. The number of photons produced per average number of participating nucleon pairs increases with the beam energy and is independent of (lie collision centrality. For collisions with similar average numbers of participating nucleons the photon multiplicities are observed to be similar for An + Au and Cu + Cu collisions at a given beam energy. The ratios of the number of charged particles to photons in the measured pseudorapidity range are found to be 1.4 +/- 0.1 and 1.2 +/- 0.1 for root(s)NN = 62.4 and 200 GeV, respectively. The energy dependence of this ratio could reflect varying contributions from baryons to charged particles, while mesons are the dominant contributors to photon production in the given kinematic region. The photon pseudorapidity distributions normalized by average number of participating nucleon pairs, when plotted as a function of eta-Y(beam), are found to follow a longitudinal scaling independent of centrality and colliding ion species at both beam energies. (C) 2009 Elsevier B.V. All rights reserved.
Resumo:
We study the beam-energy and system-size dependence of phi meson production (using the hadronic decay mode phi -> K(+) K(-)) by comparing the new results from Cu + Cu collisions and previously reported Au + Au collisions at root s(NN) = 62.4 and 200 GeV measured in the STAR experiment at RHIC. Data presented in this Letter are from mid-rapidity (vertical bar y vertical bar < 0.5) for 0.4 < p(T) < 5 GeV/c. At a given beam energy, the transverse momentum distributions for phi mesons are observed to be similar in yield and shape for Cu + Cu and Au + Au colliding systems with similar average numbers of participating nucleons. The phi meson yields in nucleus-nucleus collisions, normalized by the average number of participating nucleons, are found to be enhanced relative to those from p + p collisions. The enhancement for phi mesons lies between strange hadrons having net strangeness = 1 (K(-) and <(A)over bar>) and net strangeness = 2 (Xi). The enhancement for phi mesons is observed to be higher at root s(NN) = 200 GeV compared to 62.4 GeV. These observations for the produced phi(s (s) over bar) mesons clearly suggest that, at these collision energies, the source of enhancement of strange hadrons is related to the formation of a dense partonic medium in high energy nucleus-nucleus collisions and cannot be alone due to canonical suppression of their production in smaller systems. (C) 2009 Elsevier B.V. All rights reserved.
Resumo:
The Araes gold deposit, located in eastern Mato Grosso State, central Brazil, is hosted in Neoproterozoic volcanosedimentary rocks of the Paraguay belt, which formed during collision of the Amazonian craton and the Rio Apa block. Ar-40/Ar-39 geochronology and Pb and S isotopic analyses constrain the timing and sources of mineralization. Three biotite flakes from two samples of metavolcanic host rock yield Ar-40/Ar-39 plateau ages between 5941 and 531 Ma, interpreted as cooling ages following regional metamorphism. Clay minerals from a hydrothermal alteration zone yield an Ar-40/Ar-39 integrated age of 503 +/- 3 Ma. Galena grains from ore-bearing veins yield values of Pb-206/(204)pb from 17.952 to 18.383, Pb-207/Pb-204 from 15.156 to 15.811, and Pb-208/Pb-204 from 38.072 to 39.681. Pyrite grains from ore-bearing veins yield values of Pb-206/Pb-204 from 18.037 to 18.202, Pb-207/Pb-204 from 15.744 to 15.901., and Pb-208/(204)pb from 38.338 to 38.800. Pb isotope variations may be explained in terms of mixing a less radiogenic lead component (mu similar to 8.4) from mafic and ultramafic basement host-rocks (Nova Xavantina metavolcanosedimentary rocks) and a more radiogenic lead component (mu similar to 9.2) probably derived from supracrustal rocks (Cuiaba sedimentary groups). Sulfur isotope compositions are homogeneous, with delta S-34 values ranging from -1.1 parts per thousand to 0.9 parts per thousand (galena) and -0.7 parts per thousand to 0.9 parts per thousand (pyrite), suggesting a mantle-derived reservoir for the mineralizing solutions. Based on the Ar, Pb, and S isotope data, we suggest that the precious metals were remobilized from metavolcanic host rocks by hydrothermal solutions during Brasilide-Panafrican regional metamorphism. The Arabs gold deposit probably formed during a late stage of the orogeny, coeval with other mineralization events in the Paraguay Belt.
Resumo:
A sequence of actions in the world have influenced the information science, one of these actions is the lateral movement in how companies use their IT-systems. IT-systems today, in comparison to before, are used by companies to improve their relationship with their customers. Every year a big amount of money is spent on developing and improving IT-systems. That is why it is important to develop and create IT-systems that are clear, and which encourage, enable and simplify a user’s action. There are criteria to use in actability and “eTjänstetydlighet”. I have in this thesis used acknowledged criteria for actability and “eTjänstetydlighet” to analyze two IT-systems that are equal to each other. This is to show how companies can develop and adjust their IT-system so that they will match today’s point of view. I have also in this thesis chosen to evaluate the usage of criteria for “eTjänstetydlighet” and that is because no one has done that before. The result of this thesis gave Monster and Proffice measures for how to develop their IT-systems. The result of this thesis also gave indications of fuzziness when using criteria for “eTjänstetydlighet”, however, I was able to use the criteria the way they were supposed to be used to fulfill their purpose.
Resumo:
The association in a form of cooperative can become a guarantee factor to the activities of the small and medium producers of the apple culture in the region of Vacaria-RS, Brazil. The study shows the problems the small and medium producers that grow apples in the city have. After an overview of the literature, the thesis presents a project of a hypothetical structure with the objective of evaluating the financial and economic viability of a cooperative. In this stage the utilized methodology was the collected data available between representatives of the sector and local companies that operate on this activity. The available data was used to construct a cash flow ¿ projecting costs and expenses to an alleged project; utilizing on the sequence to the evaluation the Net Present Value Method ( NPV / Valor Presente Líquido ), the Internal Rate of Return ( IRR / Taxa Interna de Retorno ) and Pay Back ( Período de Recuperação do Investimento ¿ PRI ). The results of the economic and financial evaluation obtained reveal the acceptance of the proposed project. However, on the exemplification phase of the cooperatives that work in other regions, the social, institutional and organizational aspects showed as important as the financial aspects of the project.
Resumo:
The objective of this study is to identify how a health institution can minimize the emotional impacts caused by the change of a style of classic management for a participative administration, that the workers and controllers can see the institution as a dynamic organization, that must be faced as an alive system, mobile and adaptable, where they is beings that have the right to react and to answer to the stimulatons. For that, the institution can handle motivator¿s instruments that develop in the people the potential to react of adequate way to the changes proposals, as well as increasing the perspective of possible technological improvements and interpersonal relationship between the internal and external customers. To change the style to manage, to hear the staff of support and user, are not part of the routine of the heads that develop classic management. This decision demands adaptation and flexibility, study, update and psychological preparation, to face common feelings to the new. It fits to the new directors, to visualize these feelings and work to minimize, avoiding future upheavals and the confrontation of situations that can harm the production of the company, as well as the quality of the communication between the diverse dimensions of the organization people. In this study case, based in phenomenological methodology, was possible to verify, through half-open interviews and comments, how was faced the feelings caused at the old direction time, composed for military who withheld the power and determined the actions of the hospital in study, was replaced by health professionals, that saw in the work team the best option to solve the problems and the potential to carry through an administration based in adequate strategies the reality of the moment, with the objective of reaching the satisfaction of the customer. Through this work, is possible to prove the theory that the changes cause impacts that affect the behavior of the people involved and cause stress, as well as conclude that despite the new direction show themselves, during the change, much made use to make right and involve all the workers, didn¿t have traced strategies to minimize the emotional impacts caused by the changes, what made all face their feelings of doubts and anxiety without no special care. Many obtained, by themselves, to face and to adapt the new proposals, but some could not assimilate the new administrative methodology and had been moved away definitively from the institution.
Resumo:
Este estudo partiu da necessidade de aprofundar o conhecimento sobre a prática da Assistência Farmacêutica no contexto geral e no cotidiano do serviço de saúde do município de São Luis (Maranhão). Trata-se de um estudo exploratório, de caráter descritivo, empregando métodos quali-quantitativos, onde a coleta de dados constituiu-se da aplicação de formulário semi-estruturado aos gestores e profissionais de saúde, durante entrevista realizada em seus ambientes de trabalho. Os resultados obtidos foram sistematizados e discutidos em quatro categorias: (a) visão dos gestores e profissionais de saúde sobre a Assistência Farmacêutica; (b) percepção desses /atores sobre o papel da Assistência Farmacêutica no sistema de saúde; (c) identificação de como eles percebem a Assistência Farmacêutica disponibilizada no serviço de saúde, no que se refere ao acesso a medicamentos, orientações de uso e acompanhamento terapêutico; (d) descrição dos avanços e dificuldades no desenvolvimento da Assistência Farmacêutica municipal. As percepções referidas por estes atores delimitam a Assistência Farmacêutica disponibilizada no serviço público do município de São Luís como apresentando dificuldades em todas as suas etapas, o que repercute diretamente na deficiência da prestação de serviços e na falta de acesso da população aos medicamentos essenciais . situação que reforça a necessidade de mudanças que alterem a prática desses serviços e promova a implementação de uma política de Assistência Farmacêutica mais resolutiva, capaz de contribuir para a efetivação das ações de saúde.