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- Abraham, N G, et al.
(författare)
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Metabolic syndrome : psychosocial, neuroendocrine, and classical risk factors in type 2 diabetes
- 2007
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Ingår i: Annals of the New York Academy of Sciences. - : Wiley. - 0077-8923 .- 1749-6632. ; 1113, s. 256-275
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Tidskriftsartikel (refereegranskat)abstract
- This article summarizes some aspects of stress in the metabolic syndrome at the psychosocial, tissue, and cellular levels. The metabolic syndrome is a valuable research concept for studying population health and social-biological translation. The cluster of cardiovascular risk factors labeled the metabolic syndrome is linked with low socioeconomic status. Systematic differences in diet and physical activity contribute to social patterning of the syndrome. In addition, psychosocial factors including chronic work stress are linked with its development. Psychosocial factors could lead to metabolic perturbations and increase cardiovascular risk via activation of neuroendocrine responses, for example, in the autonomic nervous system and in several hormonal pathways. High glucocorticoid levels will promote lipid storage in visceral rather than subcutaneous adipose tissue. Adipocytes secrete several proinflammatory cytokines, which considered major contributors to increase in oxidants and cell injury. Upregulation of heme oxygenase 1 (HO-1) and peroxidase in the early development of diabetes produces a decrease in oxidative-mediated injury. Increased HO activity is associated with a significant decrease in superoxide, endothelial cell shedding and blood pressure. Finally, it is proposed that overexpression of glutathione peroxidase in beta cells may protect beta cell deterioration from oxidative stress during development of diabetes and hyperglycemia and this may result in attenuation of beta cell failure. If this proves to be the case, then the scene will be set to develop glutathione peroxidase mimetics for use in preclinical and clinical trials.
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| 2. |
- Chapman, Henry N, et al.
(författare)
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Femtosecond time-delay X-ray holography
- 2007
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 448:7154, s. 676-679
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Tidskriftsartikel (refereegranskat)abstract
- Extremely intense and ultrafast X-ray pulses from free-electron lasers offer unique opportunities to study fundamental aspects of complex transient phenomena in materials. Ultrafast time-resolved methods usually require highly synchronized pulses to initiate a transition and then probe it after a precisely defined time delay. In the X-ray regime, these methods are challenging because they require complex optical systems and diagnostics. Here we propose and apply a simple holographic measurement scheme, inspired by Newton's 'dusty mirror' experiment1, to monitor the X-ray-induced explosion of microscopic objects. The sample is placed near an X-ray mirror; after the pulse traverses the sample, triggering the reaction, it is reflected back onto the sample by the mirror to probe this reaction. The delay is encoded in the resulting diffraction pattern to an accuracy of one femtosecond, and the structural change is holographically recorded with high resolution. We apply the technique to monitor the dynamics of polystyrene spheres in intense free-electron-laser pulses, and observe an explosion occurring well after the initial pulse. Our results support the notion that X-ray flash imaging2, 3 can be used to achieve high resolution, beyond radiation damage limits for biological samples4. With upcoming ultrafast X-ray sources we will be able to explore the three-dimensional dynamics of materials at the timescale of atomic motion.
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| 3. |
- Cruz, Paulo J. S., et al.
(författare)
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Crack sensor with embedded optical fibre : Sustainable Bridges. Background document 5.3
- 2007
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Rapport (refereegranskat)abstract
- This document reports the development of a distributed optical fibre crack sensor. This sensor can be employed for detection of cracks and measurement of crack widths in concrete structures. The basic principle of operation for the crack sensor is based on intensity variation of the optical power within the optical fibre due to the initiation and opening of cracks.The present report summarizes the improvements introduced in the sensor to make it appropriate for crack monitoring in bridges, performed by researchers of the University of Minho, in Portugal. The primary objectives of the work were:1) To select the proper polymeric material for making the plate;2) To optimize the manufacture process;3) To assure the bonding between the plate sensor and concrete members;4) To determine the corresponding calibration curves of intensity losses versus the crack aperture;5) The application of the plate sensor to the monitoring of single crack RC beams and masonry slabs and the monitoring of multiple cracks on RC beams;6) The field implementation of the plate sensor.The field implementation of the plate sensor in the destructive test carried out in the ÖvikBridge, in the north of Sweden, is also included. The main purpose of this test was to demonstratethe capability of the sensor plate to detect cracks and measure the crack opening in concrete railway bridges. This report provides the description of the bridge and gives an overview of the procedures for wiring and installing the sensor plate.
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