105 research outputs found
Self-consistent quantal treatment of decay rates within the perturbed static path approximation
The framework of the Perturbed Static Path Approximation (PSPA) is used to
calculate the partition function of a finite Fermi system from a Hamiltonian
with a separable two body interaction. Therein, the collective degree of
freedom is introduced in self-consistent fashion through a Hubbard-Stratonovich
transformation. In this way all transport coefficients which dominate the decay
of a meta-stable system are defined and calculated microscopically. Otherwise
the same formalism is applied as in the Caldeira-Leggett model to deduce the
decay rate from the free energy above the so called crossover temperature
.Comment: 17 pages, LaTex, no figures; final version, accepted for publication
in PRE; e-mail: [email protected]
Electronic entropy, shell structure, and size-evolutionary patterns of metal clusters
We show that electronic-entropy effects in the size-evolutionary patterns of
relatively small (as small as 20 atoms), simple-metal clusters become prominent
already at moderate temperatures. Detailed agreement between our
finite-temperature-shell-correction-method calculations and experimental
results is obtained for certain temperatures. This agreement includes a
size-dependent smearing out of fine-structure features, accompanied by a
measurable reduction of the heights of the steps marking major-shell and
subshell closings, thus allowing for a quantitative analysis of cluster
temperatures.Comment: Latex/Revtex, 4 pages with 3 Postscript figure
Bloom dynamics of an exceptional red tide of the toxigenic dinoflagellate
The toxic dinoflagellate Alexandrium minutum generally proliferates in semi-enclosed sites such as estuaries, harbours and lagoons, where stratification, restricted circulation and accumulation of resting cysts set suitable conditions for its development. In the Galician RĂas (NW Iberian Peninsula), its blooms follow also this pattern. They are recurrent in small, shallow estuarine bays inside the RĂas, but rarely detected, and if so in minor amount, out of these areas. However, a massive proliferation of A. minutum from June to July 2018 in the RĂas Baixas (Vigo and Pontevedra) changed this picture. The bloom initiated in semi-enclosed waters, as previously described for this species, but thereafter spread to the whole embayments where persisted more than one month. It generated a noticeable red tide with disperse patches that became heavily concentrated inside the port of Vigo. During that period shellfish harvesting closures and paralytic shellfish toxins in certain marine invertebrates and fish were reported for the first time in Spain. Meteorological conditions (higher than usual rains/runoff, sustained temperature increment and oscillating wind pattern promoting a series of upwelling-relaxation cycles) fostered optimal circumstances for the outbreak of A. minutum: strong vertical stratification and the alternation of retention and dispersion processes. Simulations from a particle tracking model portrayed the observed bloom development phases: onset, transport within the surface layer towards the interior parts of the RĂa of Vigo, and dispersion all over the embayment. High concentrations of resting cysts were detected several months after the bloom, which may have favoured flourish of A. minutum in the following years, markedly in 2020
HABs in coastal upwelling systems: Insights from an exceptional red tide of the toxigenic dinoflagellate Alexandrium minutum
Alexandrium minutum blooms generally occur in semi-enclosed sites such as estuaries, harbours and lagoons, where enhanced stratification, restricted circulation and accumulation of resting cysts in the sediment set suitable habitat conditions for the proliferation of this paralytic shellfish poisoning toxigenic species. In the Galician RĂas Baixas (NW Iberian Peninsula), according to weekly time-series between 1994 and 2020, blooms of A. minutum were recurrent in small, shallow estuarine bays inside the RĂas de Vigo and Pontevedra, but rarely detected, and if so at low concentrations, out of these environments. However, from May to July 2018 it developed as usual in the small inner bays but then spread over both RĂas (Vigo and Pontevedra) causing discoloured waters during one month and prolonged harvesting closures. Meteorological conditions during that period (rains / runoff higher than climatological averages, sustained temperature increment and oscillating wind pattern –i.e., series of upwelling-relaxation cycles), fostered optimal circumstances for the development of that extensive and massive proliferation: strong vertical stratification and the alternation of retention and dispersion processes. Simulations from a particle tracking model portrayed the observed bloom development phases: onset and development inside a small inner bay; transport within the surface layer, from these sites towards the interior parts of the RĂa; and dispersion all over the embayment. Seedbeds with high concentrations of resting cysts were detected several months after the bloom, which may have favoured flourishment of A. minutum in the following two years, markedly in 2020. The present work contributes to the general understanding of the dynamics of harmful algal blooms (HABs), from which surveillance indicators of the state of marine ecosystems and their evolution can be derived. We hypothesize that the intensity and frequency of A. minutum proliferations in the Galician RĂas could increase under projected climate trends.Postprint2,69
Reliability of infrared thermography in skin temperature evaluation of wheelchair users
To examine the reliability of infrared thermography (IRT) in wheelchair users (WCUs), as a noninvasive and risk-free
technique to detect the natural thermal radiation emitted by human skin and to allow subsequent interpretations of temperature distributions
Avaliação sensorial do café cereja descascado, armazenado sob atmosfera artificial e convencional
International Alliance Strategies: A Case Study of the Indonesian Medical Device Industry
This study aims to investigate how the multinational corporations form
alliance strategies with local businesses under the dynamic institutional environment in the Indonesian context. We used a qualitative approach with a case study of the medical device industry to examine how the institutional environment affects the choice of the strategic alliance. By collecting the qualitative data, including interviews, observations and archival data, the interpretive approach was adopted to understand social worlds from the point of view of participants. We identified five types of alliance strategies: the wholly owned subsidiary with contractual collaboration, the wholly owned subsidiary with the licence agreement, the international trade with the licence agreement, joint venture and outsourcing. There are also two main issues of the institutional environments that determine the choice of alliance strategic: the restriction for foreign companies to carry out direct selling and the new policy that introduces the electronic procurement system. This study provides evidence of the role of the institutional environment on collaboration strategies between the multinational enterprises from the developed countries and the local distributors from Indonesia. The results extend the concept of international business in the Asian context
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