398 research outputs found
Intense slow beams of bosonic potassium isotopes
We report on an experimental realization of a two-dimensional magneto-optical
trap (2D-MOT) that allows the generation of cold atomic beams of 39K and 41K
bosonic potassium isotopes. The high measured fluxes up to 1.0x10^11 atoms/s
and low atomic velocities around 33 m/s are well suited for a fast and reliable
3D-MOT loading, a basilar feature for new generation experiments on
Bose-Einstein condensation of dilute atomic samples. We also present a simple
multilevel theoretical model for the calculation of the light-induced force
acting on an atom moving in a MOT. The model gives a good agreement between
predicted and measured flux and velocity values for our 2D-MOT.Comment: Updated references, 1 figure added, 10 pages, 9 figure
Collisional properties of sympathetically cooled K
We report the experimental evidence of the sympathetic cooling of K
with Rb down to 1 K, obtained in a novel tight confining magnetic
trap. This allowed us to perform the first direct measurement of the elastic
cross section of K below 50 K. The result obtained for the triplet
scattering length, Bohr radii, agrees with previous results
derived from photoassociation spectra and from Feshbach spectroscopy of
K.Comment: 7 pages, 4 figures, submitted to Phys. Rev.
Risk-Informed design process of the IRIS reactor
Westinghouse is currently conducting the pre-application licensing of the International Reactor Innovative and
Secure (IRIS). The design philosophy of the IRIS has been based on the concept of Safety-by-DesignTM and within this
framework the PSA is being used as an integral part of the design process. The basis for the PSA contribution to the design
phase of the reactor is the close iteration between the PSA team and the design and safety analysis team. In this process the
design team is not only involved in the initial phase of providing system information to the PSA team, allowing in this way the
identification of the high risk scenarios, but it is also receiving feedback from the PSA team that suggests design modification
aimed at reaching risk-related goals.
During the first iteration of this process, the design modifications proposed by the PSA team allowed reducing the initial
estimate of Core Damage Frequency (CDF) due to internal events from 2E-6/ry to 2E-8/ry. Since the IRIS design is still in a
development phase, a number of assumptions have to be confirmed when the design is finalized.
Among key assumptions are the success criteria for both the accident sequences analyzed and the systems involved in the
mitigation strategies. The PSA team developed the initial accident sequence event trees according to the information from
the preliminary analysis and feasibility studies. A recent coupling between the RELAP and GOTHIC codes made possible the
actual simulation of all LOCA sequences identified in the first draft of the Event Trees. Working in close coordination, the
PSA and the safety analysis teams developed a matrix case of sequences not only with the purpose of testing the assumed
success criteria, but also with the perspective of identifying alternative sequences developed mainly by relaxing the extremely
conservative assumptions previously made.
The results of these simulations, bounded themselves with conservative assumptions on the Core Damage definition,
suggested two new versions of the LOCA Event Tree with two possible configurations of the Automatic Depressurization
System. The new CDF has been evaluated for both configurations and the design team has been provided with an additional
and risk-related perspective that will help choosing the design alternative to be implemented
Adapting to Crisis
This article draws on our experiences of carrying out PhD research on migration during the COVID-19 pandemic. We are all involved with the University College London Migration Research Unit (MRU), and our PhD research explores the lived experiences of migrants and people affected by migration. This is the first of two articles in this issue of Migration and Society addressing the implications of COVID-19 on migration research from the perspective of postgraduate researchers. In this article, we firstly reflect on how “crises,” including the COVID-19 pandemic, inevitably shape contexts of migration research. We then share how COVID-19 has shaped our relationship to “the field” and our formal research institutions. Finally, we share how we have adapted our methodologies in response to COVID-19 and, considering the complex ethical and practical challenges posed by this context, reflect on what it means to make methodological “adaptations” in times of overlapping crises
Prediction of functional recovery in patients with chronic coronary artery disease and left ventricular dysfunction combining the evaluation of myocardial perfusion and contractile reserve using nitrate-enhanced technetium-99m Sestamibi gated single-photon emission computed tomography and dobutamine stress.
O conceito de conflitos ambientais na revista de direito ambiental no ano de 2010
Em continuidade à pesquisa sobre conflitos ambientais, realizada no ano de 2010, busca-se verificar a visão de articulistas de uma revista especializada em direito ambiental dos conflitos atuais, categorizando seus conceitos e perspectivas. No presente estudo, ainda em andamento, foram selecionados 08 artigos publicados no ano de 2010 na Revista de Direito Ambiental da Editora Revista dos Tribunais, referência na área, detentora de avaliação B2 no sistema Qualis, pertencente ao acervo da Biblioteca Central do UniFOA. Está sendo realizado, a partir da leitura dos referidos artigos, a identificação do que consiste, em cada caso, na perspectiva do autor, o conflito ambiental. Estão sendo avaliados a conceituação de conflito, identificando o bem ambiental violado, os atores envolvidos e seus papéis. O objetivo foi o de identificar os conflitos ambientais abordados nos artigos publicados, categorizar conceitos de conflitos ambientais, relacionar os argumentos utilizados e estabelecer uma relação entre os conflitos e os fundamentos utilizados para a sua solução
Evaluation of the Uro-Quick system for antibiotic susceptibility tests of strains collected from intensive care units
During the period January–June 2004, 525 pathogens isolated from intensive care units were examined with the new rapid Uro-Quick method for antibiotic susceptibility tests. The results were compared with those obtained by the reference NCCLS methods (disk diffusion or dilution). Antibiotic (in appropriate concentration) was introduced in a vial containing 2 ml of Mueller-Hin ton broth, then 0.5 ml of 5×10 or 106 cells/ml of the strain culture were added. After 3–6 h of incubation, depending on the microorganism studied, the instrument printed the results: no growth and a growth curve similar to that of the untreated control are representative of a susceptible and resistant strain respectively. The following drugs were tested: ciprofloxacin, ampicillin, aztreonam, co-clavulanate, piperacillin/tazobactam, ceftazidime, cefotaxime, cefuroxime, ceftriaxone, imipenem, amikacin, gentamicin, trimethoprim-sulfamethoxazole, clindamycin, erythromycin, linezolid, penicillin, tetracycline, vancomycin, oxacillin. Gram-negative strains tested were 252 and Gram-positive 273: agreement between the two methods ranged from 85.6% (piperacillin/tazobactam) to 98.5% (ciprofloxact) in Gram-negative pathogens, from 90 to 100% in Gram-positive, with the exception of erythromycin (84.2%) against enterococci. On the basis of the present findings the Uro-Quick system appears to be very useful for the rapid detection of antibiotic susceptibility in pathogens collected from intensive care units
International migration of unaccompanied minors: trends, health risks, and legal protection
The global population of unaccompanied minors—children and adolescents younger than 18 years who migrate without their legal guardians—is increasing. However, as data are not systematically collected in any region, if collected at all, little is known about this diverse group of young people. Compared with adult migrants, unaccompanied minors are at greater risk of harm to their health and integrity because they do not have the protection provided by a family, which can affect their short-term and long-term health. This Review summarises evidence regarding the international migration and health of unaccompanied minors. Unaccompanied minors are entitled to protection that should follow their best interests as a primary consideration; however, detention, sometimes under the guise of protection, is a widespread practice. If these minors are provided with appropriate forms of protection, including health and psychosocial care, they can thrive and have good long-term outcomes. Instead, hostile immigration practices persist, which are not in the best interests of the child
Conflitos ambientais a luz dos pressupostos procedimentais de democracia
Os conflitos ambientais, em especial na Região Sul-Fluminense, representam uma parcela significativa das questões de tensão entre sociedade, empresariado e Poder Público, gerando atritos na relação entre estes atores. A aplicação de técnicas de mediação, por meio do seu potencial racionalizador do debate, torna-se um instrumento teórico importante para a resolução dos conflitos ambientais. Isto porque, enquanto os ecossistemas sofrem alterações lentas e continuas devido às leis físicas, a história demonstra uma aceleração progressiva da evolução pela qual passa o homem, que, para satisfazer suas necessidades ilimitadas, disputa os bens da natureza, que são limitados, acentuando o desequilíbrio ecológico e, consequentemente, gerando conflitos na comunidade, pois se utilizam recursos pertencentes às gerações futuras. A criação de medidas alternativas como o desenvolvimento sustentável, cuja característica principal consiste na possível e desejável conciliação entre o desenvolvimento, a preservação do meio ambiente e a melhoria da qualidade de vida, seria uma forma de resolução do problema. O desenvolvimento sustentável é um processo de mudança no qual o uso de recursos, as políticas econômicas, a dinâmica populacional e as estruturas institucionais estão em harmonia e reforçam o potencial atual e futuro para o progresso humano. Apesar de reconhecer que as atividades econômicas devem caber à iniciativa privada, a busca do desenvolvimento sustentável exigirá, sempre que necessário, a interação dos atores envolvidos nos campos social, ambiental, econômico, judicial e de ordem pública, de modo a garantir democraticamente um mínimo de qualidade devida para todos. E tal objetivo será concretizado a partir da utilização da mediação como instrumento de resolução dos conflitos mencionados.
One-Dimensional Discrete Stark Hamiltonian and Resonance Scattering by Impurities
A one-dimensional discrete Stark Hamiltonian with a continuous electric field
is constructed by extension theory methods. In absence of the impurities the
model is proved to be exactly solvable, the spectrum is shown to be simple,
continuous, filling the real axis; the eigenfunctions, the resolvent and the
spectral measure are constructed explicitly. For this (unperturbed) system the
resonance spectrum is shown to be empty. The model considering impurity in a
single node is also constructed using the operator extension theory methods.
The spectral analysis is performed and the dispersion equation for the
resolvent singularities is obtained. The resonance spectrum is shown to contain
infinite discrete set of resonances. One-to-one correspondence of the
constructed Hamiltonian to some Lee-Friedrichs model is established.Comment: 20 pages, Latex, no figure
- …