954 resultados para Social structure and change


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In Duchenne muscular dystrophy, the absence of dystrophin causes progressive muscle wasting and premature death. Excessive calcium influx is thought to initiate the pathogenic cascade, resulting in muscle cell death. Urocortins (Ucns) have protected muscle in several experimental paradigms. Herein, we demonstrate that daily s.c. injections of either Ucn 1 or Ucn 2 to 3-week-old dystrophic mdx(5Cv) mice for 2 weeks increased skeletal muscle mass and normalized plasma creatine kinase activity. Histological examination showed that Ucns remarkably reduced necrosis in the diaphragm and slow- and fast-twitch muscles. Ucns improved muscle resistance to mechanical stress provoked by repetitive tetanizations. Ucn 2 treatment resulted in faster kinetics of contraction and relaxation and a rightward shift of the force-frequency curve, suggesting improved calcium homeostasis. Ucn 2 decreased calcium influx into freshly isolated dystrophic muscles. Pharmacological manipulation demonstrated that the mechanism involved the corticotropin-releasing factor type 2 receptor, cAMP elevation, and activation of both protein kinase A and the cAMP-binding protein Epac. Moreover, both STIM1, the calcium sensor that initiates the assembly of store-operated channels, and the calcium-independent phospholipase A(2) that activates these channels were reduced in dystrophic muscle by Ucn 2. Altogether, our results demonstrate the high potency of Ucns for improving dystrophic muscle structure and function, suggesting that these peptides may be considered for treatment of Duchenne muscular dystrophy.

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This work focuses on the study of the relationship between ownership and control structure of the company and its innovative activity. Its aim consists of analysing the role that may be played by determinants within the company related to ownership structure when the decision to incur research and development activities is taken as well as on the output of this innovate process. Among these determinants we may think of issues such as who owns the firm and how the control of decision-making is distributed, the nature of this control and the level of concentration of ownership, among others. The study is carried out for the year 2001 using a representative sample of Spanish manufacturing industries.

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Nanocrystalline silicon layers have been obtained by thermal annealing of films sputtered in various hydrogen partial pressures. The as-deposited and crystallized films were investigated by infrared, Raman, x-ray diffraction, electron microscopy, and optical absorption techniques. The obtained data show evidence of a close correlation between the microstructure and properties of the processed material, and the hydrogen content in the as-grown deposit. The minimum stress deduced from Raman was found to correspond to the widest band gap and to a maximum hydrogen content in the basic unannealed sample. Such a structure relaxation seems to originate from the so-called "chemical annealing" thought to be due to Si-H2 species, as identified by infrared spectroscopy. The variation of the band gap has been interpreted in terms of the changes in the band tails associated with the disorder which would be induced by stress. Finally, the layers originally deposited with the highest hydrogen pressure show a lowest stress-which does not correlate with the hydrogen content and the optical band gap¿and some texturing. These features are likely related to the presence in these layers of a significant crystalline fraction already before annealing.

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OBJECTIVES: The present study examines whether depressed mood and external control mediate or moderate the relationship between the number of social roles and alcohol use. PARTICIPANTS: The analysis was based on a national representative sample of 25- to 45-year-old male and female drinkers in Switzerland. METHOD: The influence of depressed mood and external control on the relationship between the number of social roles (parenthood, partnership, employment) and alcohol use was examined in linear structural equation models (mediation) and in multiple regressions (moderation) stratified by gender. All analyses were adjusted for age and education level. RESULTS: Holding more roles was associated with lower alcohol use, lower external control and lower depressed mood. The study did not find evidence of depressed mood or external control mediating the social roles-alcohol relationship. A moderation effect was identified among women only, whereby a protective effect of having more roles could not be found among those who scored high on external control. In general, a stronger link was observed between roles and alcohol use, while depressed mood and external control acted independently on drinking. With the exception of women with high external control, the study found no link between a higher number of social roles and greater alcohol use. CONCLUSION: Our results indicate that drinking behaviours are more strongly linked to external control and depressed mood than they are to the number of social roles. The study also demonstrates that in any effective alcohol prevention policy, societal actions that enable individuals to combine more social roles play a central role.

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Different management systems tend to modify soil structure and porosity over the years. The aim of this study was to study modifications in the morphostructure and porosity of dystroferric Red Latosol (Oxisol) under conventional tillage and no-tillage over a 31- year period. The study began with the description of soil profiles based on the cropping profile method, to identify the most compact structures, define sample collection points for physical and chemical analysis, and determine the water retention curve. A forest soil profile was described and used as reference. The results showed that, under conventional tillage, the microaggregate structure of the Oxisol was fragmented between 0 and 0.20 m, and compact (bulk density = 1.52 Mg m-3) in the sub-surface layer between 0.20 and 0.50 m. Under no-tillage, the structure became compacted (bulk density = 1.40 Mg m-3) between 0 and 0.60 m, but contained fissures and biopores. The volume of the class with a pore diameter of > 100 µm under no-tillage was limited, but practically non-existent in the conventional management system. On the other hand, the classes with a pore diameter of < 100 µm were not affected by the type of soil management system.

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This work focuses on the study of the relationship between ownership and control structure of the company and its innovative activity. Its aim consists of analysing the role that may be played by determinants within the company related to ownership structure when the decision to incur research and development activities is taken as well as on the output of this innovate process. Among these determinants we may think of issues such as who owns the firm and how the control of decision-making is distributed, the nature of this control and the level of concentration of ownership, among others. The study is carried out for the year 2001 using a representative sample of Spanish manufacturing industries.

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Using a finite-range density functional, we have investigated the energetics and structural features of mixed helium clusters. The possibility of doping the cluster with a molecule of sulfur hexafluoride is also considered. It is seen that the repulsion introduced by the impurity strongly modifies the properties of the smallest drops. Although only a qualitative comparison is possible, the gross features displayed by our calculations are in agreement with recent experimental findings.

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We have investigated edge modes of different multipolarity sustained by quantum antidots at zero magnetic field. The ground state of the antidot is described within a local-density-functional formalism. Two sum rules, which are exact within this formalism, have been derived and used to evaluate the energy of edge collective modes as a function of the surface density and the size of the antidot.

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Although there is significant interest in the social role of sport in fostering civil society from both policymakers and academics, there is a lack of evidence of the specific role of sport federations in this system. This book critically presents the mechanisms and structures in a selection of sport federations within a variety of European countries that illuminate the varied relationships between not-for-profit sport federations, their members, governments and the citizens they represent. The contributors explore the contrasts and synergies between core social capital theoretical perspectives, and how these may be informed by and/or shape the realities of governance from different perspectives within the sport system.

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The introduction and intensification of no-tillage systems in Brazilian agriculture in recent decades have created a new scenario, increasing concerns about soil physical properties. The objective of this study was to assess the effects of different tillage systems on some physical properties of an Ultisol previously under native grassland. Five tillage methods were tested: no-tillage (NT), chiseling (Ch), no-tillage with chiseling every two years (NTCh2), chiseling using an equipment with a clod-breaking roller (ChR) and chiseling followed by disking (ChD). The bulk density, macroporosity, microporosity and total porosity, mechanical resistance to penetration, water infiltration into the soil and crop yields were evaluated. The values of soil bulk density, mechanical resistance to penetration and microporosity increased as macroporosity decreased. Soil bulk density was lower in tillage systems with higher levels of tillage/soil mobilization; highest values were observed in NT and the lowest in the ChD system. The water infiltration rate was highest in the ChR system, followed by the systems ChD, NT and NTCh2, while crop yields were higher in systems with less soil mobilization.