264 resultados para Long-Term Potentiation
Resumo:
Abstract Objective To determine if high umbilical artery Doppler (UAD) pulsatility index (PI) is associated with cardio-vascular (CV) risk-factors in children at age 12 years. Methods We studied 195 children at age 12 years who had had in-utero UAD studies performed at 28 weeks gestation. The children were grouped according to whether their umbilical Doppler PI was high (indicating poor feto-placental circulation) or normal. At age 12 years we assessed CV risk factors, including anthropometric measures, blood pressure, pulse wave velocity (a measure of arterial compliance), cardio-respiratory fitness and homocysteine and cholesterol serum levels. Results Compared with children with a normal UAD PI (N=88), the children (N=107) with high UAD PI had higher resting pulse rate (p=0.04), higher pulse wave velocity (p=0.046), higher serum homocysteine levels (p=0.032) and reduced arterial compliance (7.58 v 8.50 m/sec, p=0.029) using univariate analysis. These differences were not present when adjusting for cofounders was modelled. Conclusion High PI on UAD testing in-utero may be associated with increased likelihood of some cardio-vascular risk factors at age 12-years but confounding variables may be as important. Our study raises possible long-term benefits of in-utero UAD measurements.
Resumo:
In this paper, we use qualitative research techniques to examine the role of general practitioners in the management of the long-term sickness absence. In order to uncover the perspectives of all the main agents affected by the actions of general practitioners, a case study approach focussing on one particular employment sector, the public health service, is adopted. The role of family physicians is viewed from the perspectives of health service managers, occupational health physicians, employees / patients, and general practitioners. Our argument is theoretically framed by Talcott Parsons’s model of the medical contribution to the sick role, along with subsequent conceptualisations of the social role and position of physicians. Sixty one semi-structured interviews and three focus group interviews were conducted in three Health and Social Care Trusts in Northern Ireland between 2010 and 2012. There was a consensus among respondents that general practitioners put far more weight on the preferences and needs of their patients than they did on the requirements of employing organisations. This was explained by respondents in terms of the propinquity and longevity of relationships between doctors and their patients, and by the ideology of holistic care and patient advocacy that general practitioners viewed as providing the foundations of their approach to patients. The approach of general practitioners was viewed negatively by managers and occupational health physicians, and more positively by general practitioners and patients. However, there is some evidence that general practitioners would be prepared to forfeit their role as validators of sick leave. Given the imperatives of both state and capital to reduce the financial burden of long-term sickness, this preparedness puts into doubt the continued role of general practitioners as gatekeepers to legitimate long-term sickness absence.
Resumo:
Hundsalm ice cave located at 1520 m altitude in a karst region of western Austria contains up to 7-m-thick deposits of snow, firn and congelation ice. Wood fragments exposed in the lower parts of an ice and firn wall were radiocarbon accelerator mass spectrometry (AMS) dated. Although the local stratigraphy is complex, the 19 individual dates - the largest currently available radiocarbon dataset for an Alpine ice cave - allow to place constraints on the accumulation and ablation history of the cave ice. Most of the cave was either ice free or contained only a small firn and ice body during the 'Roman Warm Period'; dates of three wood fragments mark the onset of firn and ice build-up in the 6th and 7th century ad. In the central part of the cave, the oldest samples date back to the 13th century and record ice growth coeval with the onset of the 'Little Ice Age'. The majority of the ice and firn deposit, albeit compromised by a disturbed stratigraphy, appears to have been formed during the subsequent centuries, supported by wood samples from the 15th to the 17th century. The oldest wood remains found so far inside the ice is from the end of the Bronze Age and implies that local relics of prehistoric ice may be preserved in this cave. The wood record from Hundsalm ice cave shows parallels to the Alpine glacier history of the last three millennia, for example, the lack of preserved wood remains during periods of known glacier minima, and underscores the potential of firn and ice in karst cavities as a long-term palaeoclimate archive, which has been degrading at an alarming rate in recent years. © The Author(s) 2013.
Resumo:
This paper presents the finite element (FE) analysis of the consolidation of the foundation of an embankment constructed over soft clay deposit which shows significant time dependent behaviour and was improved with prefabricated vertical drains. To assess the capability of a simple elastic viscoplastic (EVP) model to predict the long term performance of a geotechnical structure constructed on soft soils, a well documented (Leneghans) embankment was analyzed to predict its long term behaviour characteristics. Two fully coupled two dimensional (2D) plane strain FE analyses have been carried out. In one of these, the foundation of the embankment was modelled with a relatively simpler time dependent EVP model and in the other one, for comparison purposes, the foundation soil was modelled with elasto-plastic Modified Cam-clay (MCC) model. Details of the analyses and the results are discussed in comparison with the field performance. Predictions from the creep (EVP) model were found to be better than those from Elasto-plastic (MCC) analysis. However, the creep analysis requires an additional parameter and additional computational time and resources. © 2011 Taylor & Francis.
Resumo:
Geo-synthetic reinforcements are often used to enhance the stability of geotechnical structures such as embankments. These geosynthetic polymers often show significant creep deformational behaviour. In the short-term performance of a geotechnical structure, it may not play a significant role. However, while dealing with the long term behaviour, it is necessary to investigate its effect. In this paper two plane strain fully coupled finite element analysis have been conducted; one with and the other without taking into account of the creep behaviour of geosynthetics. A well documented field case of Leneghans embankment (Geogrid improved wide embankment constructed near Sydney, Australia in 1990s) have been used for this purpose. It is evident from the analyses that though the geosynthetic reinforcements may play a vital role in the performance/stability of an embankment in the early days (during and after construction), its contribution may become insignificant with time and the creep of geo-synthetic may not play a significant role in the long term stability. © 2012 American Society of Civil Engineers.