990 resultados para Environment stability


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Solid-phase extraction (SPE) in tandem with dispersive liquid-liquid microextraction (DLLME) has been developed for the determination of mononitrotoluenes (MNTs) in several aquatic samples using gas chromatography-flame ionization (GC-FID) detection system. In the hyphenated SPE-DLLME, initially MNTs were extracted from a large volume of aqueous samples (100 mL) into a 500-mg octadecyl silane (C(18) ) sorbent. After the elution of analytes from the sorbent with acetonitrile, the obtained solution was put under the DLLME procedure, so that the extra preconcentration factors could be achieved. The parameters influencing the extraction efficiency such as breakthrough volume, type and volume of the elution solvent (disperser solvent) and extracting solvent, as well as the salt addition, were studied and optimized. The calibration curves were linear in the range of 0.5-500 μg/L and the limit of detection for all analytes was found to be 0.2 μg/L. The relative standard deviations (for 0.75 μg/L of MNTs) without internal standard varied from 2.0 to 6.4% (n=5). The relative recoveries of the well, river and sea water samples, spiked at the concentration level of 0.75 μg/L of the analytes, were in the range of 85-118%.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In a biophysical approach to the study of swimming performance (blending biomechanics and bioenergetics), inter-limb coordination is typically considered and analysed to improve propulsion and propelling efficiency. In this approach, 'opposition' or 'continuous' patterns of inter-limb coordination, where continuity between propulsive actions occurs, are promoted in the acquisition of expertise. Indeed a 'continuous' pattern theoretically minimizes intra-cyclic speed variations of the centre of mass. Consequently, it may also minimize the energy cost of locomotion. However, in skilled swimming performance there is a need to strike a delicate balance between inter-limb coordination pattern stability and variability, suggesting the absence of an 'ideal' pattern of coordination toward which all swimmers must converge or seek to imitate. Instead, an ecological dynamics framework advocates that there is an intertwined relationship between the specific intentions, perceptions and actions of individual swimmers, which constrains this relationship between coordination pattern stability and variability. This perspective explains how behaviours emerge from a set of interacting constraints, which each swimmer has to satisfy in order to achieve specific task performance goals and produce particular task outcomes. This overview updates understanding on inter-limb coordination in swimming to analyse the relationship between coordination variability and stability in relation to interacting constraints (related to task, environment and organism) that swimmers may encounter during training and performance.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Mass wasting at continental margins on a global scale during the Middle Ordovician has recently been related to high meteorite influx. Although a high meteorite influx during the Ordovician should not be neglected, we challenge the idea that mass wasting was mainly produced by meteorite impacts over a period of almost 10 Ma. Having strong arguments against the impact-related hypothesis, we propose an alternative explanation, which is based on a re-evaluation of the mass wasting sites, considering their plate-tectonic distribution and the global sea level curve. A striking and important feature is the distribution of most of the mass wasting sites along continental margins characterised by periods of magmatism, terrane accretion and continental or back-arc rifting, respectively, related to subduction of oceanic lithosphere. Such processes are commonly connected with seismic activity causing earthquakes, which can cause downslope movement of sediment and rock. Considering all that, it seems more likely that most of this mass wasting was triggered by earthquakes related to plate-tectonic processes, which caused destabilisation of continental margins resulting in megabreccias and debris flows. Moreover, the period of mass wasting coincides with sea level drops during global sea level lowstand. In some cases, sea level drops can release pore-water overpressure reducing sediment strength and hence promoting instability of sediment at continental margins. Reduced pore-water overpressure can also destabilise gas hydrate-bearing sediment, causing slope failure, and thus resulting in submarine mass wasting. Overall, the global mass wasting during the Middle Ordovician does not need meteoritic trigger. (C) 2010 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The purpose of the study is: (1) to describe how nursing students' experienced their clinical learning environment and the supervision given by staff nurses working in hospital settings; and (2) to develop and test an evaluation scale of Clinical Learning Environment and Supervision (CLES). The study has been carried out in different phases. The pilot study (n=163) explored the association between the characteristics of a ward and its evaluation as a learning environment by students. The second version of research instrument (which was developed by the results of this pilot study) were tested by an expert panel (n=9 nurse teachers) and test-retest group formed by student nurses (n=38). After this evaluative phase, the CLES was formed as the basic research instrument for this study and it was tested with the Finnish main sample (n=416). In this phase, a concurrent validity instrument (Dunn & Burnett 1995) was used to confirm the validation process of CLES. The international comparative study was made by comparing the Finnish main sample with a British sample (n=142). The international comparative study was necessary for two reasons. In the instrument developing process, there is a need to test the new instrument in some other nursing culture. Other reason for comparative international study is the reflecting the impact of open employment markets in the European Union (EU) on the need to evaluate and to integrate EU health care educational systems. The results showed that the individualised supervision system is the most used supervision model and the supervisory relationship with personal mentor is the most meaningful single element of supervision evaluated by nursing students. The ward atmosphere and the management style of ward manager are the most important environmental factors of the clinical ward. The study integrates two theoretical elements - learning environment and supervision - in developing a preliminary theoretical model. The comparative international study showed that, Finnish students were more satisfied and evaluated their clinical placements and supervision with higher scores than students in the United Kingdom (UK). The difference between groups was statistical highly significant (p= 0.000). In the UK, clinical placements were longer but students met their nurse teachers less frequently than students in Finland. Arrangements for supervision were similar. This research process has produced the evaluation scale (CLES), which can be used in research and quality assessments of clinical learning environment and supervision in Finland and in the UK. CLES consists of 27 items and it is sub-divided into five sub-dimensions. Cronbach's alpha coefficient varied from high 0.94 to marginal 0.73. CLES is a compact evaluation scale and user-friendliness makes it suitable for continuing evaluation.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This paper retakes previous work of the authors, about the relationship between non-quasi-competitiveness (the increase in price caused by an increase in the number of oligopolists) and stability of the equilibrium in the classical Cournot oligopoly model. Though it has been widely accepted in the literature that the loss of quasi-competitiveness is linked, in the long run as new firms entered the market, to instability of the model, the authors in their previous work put forward a model in which a situation of monopoly changed to duopoly losing quasi-competitiveness but maintaining the stability of the equilibrium. That model could not, at the time, be extended to any number of oligopolists. The present paper exhibits such an extension. An oligopoly model is shown in which the loss of quasi-competitiveness resists the presence in the market of as many firms as one wishes and where the successive Cournot's equilibrium points are unique and asymptotically stable. In this way, for the first time, the conjecture that non-quasi- competitiveness and instability were equivalent in the long run, is proved false.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

BACKGROUND: Complex foot and ankle fractures, such as calcaneum fractures or Lisfranc dislocations, are often associated with a poor outcome, especially in terms of gait capacity. Indeed, degenerative changes often lead to chronic pain and chronic functional limitations. Prescription footwear represents an important therapeutic tool during the rehabilitation process. Local Dynamic Stability (LDS) is the ability of locomotor system to maintain continuous walking by accommodating small perturbations that occur naturally during walking. Because it reflects the degree of control over the gait, LDS has been advocated as a relevant indicator for evaluating different conditions and pathologies. The aim of this study was to analyze changes in LDS induced by orthopaedic shoes in patients with persistent foot and ankle injuries. We hypothesised that footwear adaptation might help patients to improve gait control, which could lead to higher LDS: METHODS: Twenty-five middle-aged inpatients (5 females, 20 males) participated in the study. They were treated for chronic post-traumatic disabilities following ankle and/or foot fractures in a Swiss rehabilitation clinic. During their stay, included inpatients received orthopaedic shoes with custom-made orthoses (insoles). They performed two 30s walking trials with standard shoes and two 30s trials with orthopaedic shoes. A triaxial motion sensor recorded 3D accelerations at the lower back level. LDS was assessed by computing divergence exponents in the acceleration signals (maximal Lyapunov exponents). Pain was evaluated with Visual Analogue Scale (VAS). LDS and pain differences between the trials with standard shoes and the trials with orthopaedic shoes were assessed. RESULTS: Orthopaedic shoes significantly improved LDS in the three axes (medio-lateral: 10% relative change, paired t-test p < 0.001; vertical: 9%, p = 0.03; antero-posterior: 7%, p = 0.04). A significant decrease in pain level (VAS score -29%) was observed. CONCLUSIONS: Footwear adaptation led to pain relief and to improved foot & ankle proprioception. It is likely that that enhancement allows patients to better control foot placement. As a result, higher dynamic stability has been observed. LDS seems therefore a valuable index that could be used in early evaluation of footwear outcome in clinical settings.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Craniopharyngiomas (CP) are benign epithelial tumors of the sellar region and can be clinicopathologically distinguished into adamantinomatous (adaCP) and papillary (papCP) variants. Both subtypes are classified according to the World Health Organization grade I, but their irregular digitate brain infiltration makes any complete surgical resection difficult to obtain. Herein, we characterized the cellular interface between the tumor and the surrounding brain tissue in 48 CP (41 adaCP and seven papCP) compared to non-neuroepithelial tumors, i.e., 12 cavernous hemangiomas, 10 meningiomas, and 14 metastases using antibodies directed against glial fibrillary acid protein (GFAP), vimentin, nestin, microtubule-associated protein 2 (MAP2) splice variants, and tenascin-C. We identified a specific cell population characterized by the coexpression of nestin, MAP2, and GFAP within the invasion niche of the adamantinomatous subtype. This was especially prominent along the finger-like protrusions. A similar population of presumably astroglial precursors was not visible in other lesions under study, which characterize them as distinct histopathological feature of adaCP. Furthermore, the outer tumor cell layer of adaCP showed a distinct expression of MAP2, a novel finding helpful in the differential diagnosis of epithelial tumors in the sellar region. Our data support the hypothesis that adaCP, unlike other non-neuroepithelial tumors of the central nervous system, create a tumor-specific cellular environment at the tumor-brain junction. Whether this facilitates the characteristic infiltrative growth pattern or is the consequence of an activated Wnt signaling pathway, detectable in 90% of these tumors, will need further consideration.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Os fluxos gerados pela economia de Cabo Verde, desde sempre, foram insuficientes para financiar o seu desenvolvimento, devido aos constrangimentos relativas à falta de recursos naturais, ao défice da balança comercial e à dimensão e fragmentação do território. Neste sentido, o capital estrangeiro surge como um recurso estratégico no desenvolvimento de CV, sendo um instrumento chave para colmatar alguns défices da economia cabo-verdiana. Logo a relevância do estudo proposto, que parte da questão: “Os incentivos e o ambiente oferecidos por CV têm sido suficientemente eficientes para atrair o IDE ou os números poderiam estar melhores?” Na sequência da revisão teórica e da literatura, a fim de obter a resposta à pergunta da pesquisa, analisamos os incentivos e o ambiente oferecidos aos investidores externos, através de instrumentos empreendidos pelo Governo de CV e analisamos a evolução dos fluxos do IDE no país, com especial atenção ao período 2000-2006, a partir de dados estatísticos. A análise posterior – percepção dos investidores externos em CV – deu lugar a um estudo qualitativo, a partir de um inquérito efectuado à uma amostragem probabilística de dez investidores externos, elegidos a partir de critérios fundamentados. Como resultado, observamos que os instrumentos empreendidos pelo Governo na atracção do IDE têm mais de dez anos de existência, não coincidindo com os maiores picos de IDE em CV ocorridos nos dois últimos anos. Observamos, ainda, que, de uma forma geral, os investidores externos privilegiam o mercado cabo-verdiano pela estabilidade política e económica. Por outro lado, apontam grandes constrangimentos a nível de infra-estrutura, ligações marítimas internas e aéreo para o exterior. As formalidades administrativas foram, também, objecto de avaliação negativa por parte dos investidores inquiridos. Posto isto, concluímos que, de uma forma geral, os instrumentos de atracção ao IDE em CV não são suficientemente eficazes para atender às necessidades dos investidores externos. Isto demonstra que há um interessante terreno a ser explorado. The cash flows generated Cape Verde’s economy, so far, have been insufficient to finance its development, due to constraints concerning the lack of natural resources, the trade balance deficit and the geographical distribution and dimension of the territory. In this context, foreign capital appears as a strategic resource for Cape Verde’s development. Foreign investment is a significant instrument to overcome some shortfalls of the cape-verdean economy. Therefore the relevance of this study which is based on the question: "The incentives offered by CV and the environment have been effective enough to attract FDI or the numbers could be better?" Following the literature and theoretical review, in order to get the answer to the research question, we have analyzed the stimulus and environment provided to foreign investors through instruments launched by the Government. We have analysed the evolution of FDI´s flows into the country, with particular focus on the period 2000 - 2006, from statistical data. The subsequent analysis - the perception of foreign investors in CV - produced a qualitative survey study, conduced on a sampling of ten foreign investors, selected from founded criterions. As a result, we observed that the instruments undertaken by the Government in attracting FDI are over than ten years old and the higher FDI peak took place during the two last years. It was noticed that foreign investors choose the cape-verdean market because of its politic and economic stability. On the other hand, foreign investors show great constraints in terms of infrastructure, internal maritime connection and international flight connections. The administrative formalities are also subject of a negative evaluation by the investors surveyed. We have eventually figured out that the attraction instruments for FDI in CV are not effective enough for the needs of foreign investors. This demonstrates that there is a interesting ground to be explored.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Objective: To identify and analyze the production of knowledge about the strategies that health care institutions have implemented to humanize care of hospitalized children. Method: This is a systematic review conducted in the Virtual Health Library - Nursing and SciELO, using the seven steps proposed by the Cochrane Handbook. Results: 15 studies were selected, and strategies that involved relationship exchanges were used between the health professional, the hospitalized child and their families, which may be mediated by leisure activities, music and by reading fairy tales. We also include the use of the architecture itself as a way of providing welfare to the child and his/her family, as well as facilitating the development of the work process of health professionals. Conclusion: Investments in research and publications about the topic are necessary, so that, the National Humanization Policy does not disappear and that the identified strategies in this study do not configure as isolated and disjointed actions of health policy.


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Objective: Testing the psychometric properties of the Portuguese version of the Practice Environment Scale of the Nursing Work Index. Method: A descriptive, analytical and cross-sectional study, for the cross-cultural adaptation and validation of the psychometric properties of the scale. The study participants were 236 nurses from two hospitals in the regions of Lisbon and Vale do Tejo. Results: The 0.92 Cronbach’s alpha was obtained for overall reliability and support of a five-dimension structure. Conclusion: The excellent quality of adjustment of analysis confirms the validity of the adapted version to hospital care settings, although there was no total coincidence of items in the five dimensions


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Objective: Presenting a Virtual Environment (VE) based on the Protocol of Treatment of Hypertension and Diabetes Mellitus type 2, used in Primary Care for evaluation of dietary habits in nursing consultations. Method: An experimental study applied by two nurses and a nurse manager, in a sample of 30 deaf patients aged between 30 and 60 years. The environment was built in Visual Basic NET and offered eight screens about feeding containing food pictures, videos in Libras (Brazilian sign language) and audio. The analysis of the VE was done through questionnaires applied to patients and professionals by the Poisson statistical test. Results: The VE shows the possible diagnostics in red, yellow, green and blue colors, depending on the degree of patients’ need. Conclusion: The environment obtained excellent acceptance by patients and nurses, allowing great interaction between them, even without an interpreter. The time in consultation was reduced to 15 minutes, with the preservation of patient privacy.