Membrane Cholesterol Regulates Smooth Muscle Phasic Contraction

The regulation of contractile activity in smooth muscle cells involves rapid discrimination and processing of a multitude of simultaneous signals impinging on the membrane before an integrated functional response can be generated. The sarcolemma of smooth muscle cells is segregated into caveolar regions-largely identical with cholesterol-rich membrane rafts—and actin-attachment sites, localized in non-raft, glycerophospholipid regions. Here we demonstrate that selective extraction of cholesterol abolishes membrane segregation and disassembles caveolae. Simultaneous measurements of force and [Ca2+]i in rat ureters demonstrated that extraction of cholesterol resulted in inhibition of both force and intracellular Ca2+ signals. Considering the major structural reorganization of cholesterol-depleted sarcolemma, it is intriguing to note that decreased levels of membrane cholesterol are accompanied by a highly specific inhibition of phasic, but not tonic contractions. This implies that signalling cascades that ultimately lead to either phasic or tonic response may be spatially segregated in the plane of the sarcolemma. Replenishment of cholesterol restores normal contractile behavior. In addition, the tissue function is re-established by inhibiting the large-conductance K+-channel. Sucrose gradient ultracentrifugation in combination with Western blotting analysis demonstrates that its α-subunit is associated with detergent-resistant membranes, suggesting that the channel might be localized within the membrane rafts in vivo. These findings are important in understanding the complex signalling pathways in smooth muscle and conditions such as premature labor and hypertensio

Using Participatory Scenarios to Stimulate Social Learning for Collaborative Sustainable Development

Interdependent human and biophysical systems are highly complex and behave in unpredictable and uncontrollable ways. Social and ecological challenges that emerge from this complexity often defy straightforward solutions, and efforts to address these problems will require not only scientific and technological capabilities but also learning and adaptation. Scenarios are a useful tool for grappling with the uncertainty and complexity of social-ecological challenges because they enable participants to build adaptive capacity through the contemplation of multiple future possibilities. Furthermore, scenarios provide a platform for social learning, which is critical to acting in the face of uncertain, complex, and conflict-laden problems. We studied the Minnesota 2050 project, a collaborative project through which citizens collectively imagined future scenarios and contemplated the implications of these possibilities for the adaptability of their social and environmental communities. Survey and interview data indicate that these participatory scenario workshops built and strengthened relationships, enhanced participants’ understanding of other perspectives, and triggered systemic thinking, all of which is relevant to collective efforts to respond to social-ecological challenges through sustainable development activities. Our analysis shows that participatory scenarios can stimulate social learning by enabling participants to engage and to discuss options for coping with uncertainty through collaborative actions. Such learning can be of value to participants and to the organizations and decisions in which they are engaged, and scenario processes can be effective tools for supporting collaborative sustainable development efforts

A multispectral photographic experiment based on a statistical analysis of spectrometric data Final report

Multispectral photographic experiment based on statistical analysis of spectrometric data - spectral reflectance for terrain, optimum film- filter combinations, and terrain tone signature

Pharmacokinetics of a Single Feeding of Pelleted Cannabidiol in Horses

Claims about cannabidiol (CBD) supplementation improving health and behavior are extensive, but research is lacking. Some studies have shown decreased anxiety behavior in rats, and increased activity in osteoarthritic dogs supplemented with CBD, but even less research exists on horses. This study monitored pharmacokinetics and short-term safety for 3 CBD dosages. Eighteen Quarter Horse geldings were randomly assigned to 3 treatment groups: 50 mg (TXT1), 100 mg (TXT2), and 250 mg (TXT3). Dosage was derived from manufacturer recommendations and existing literature on other species. Horses were fed a single dose of CBD pellets. Blood was collected pre- and post-treatment at 0.5, 1, 2, 4 and 12 hr. Serum was analyzed for CBD and serum chemistry, and plasma was analyzed for a complete blood chemistry (CBC) evaluation. Statistics were completed on serum chemistry using PROC MIXED procedure of SAS. Serum chemistry and CBC results were within normal parameters; however, treatment differences were observed for BUN (TXT1=15.50, TXT2=16.52, TXT3=18.61; P≤0.03) and creatinine (TXT1=1.41, TXT2=1.22, TXT3=1.49; P≤0.01). In other species, peak CBD concentrations occur approximately 2 hr post treatment. Peak serum concentrations were detected in 1 of 6 TXT2 horses and 5 of 6 TXT3 horses at 2 hr post treatment. This data can be used to support further research to determine correct and safe doses of CBD in horses

Estudo do aproveitamento de quatro resíduos agroindustriais para produção de carvão vegetal.

Resumo. Disponível online. MIPE

Bose-Einstein Condensation at a Helium Surface

Path Integral Monte Carlo was used to calculate the Bose-Einstein condensate fraction at the surface of a helium film at $T=0.77 K$, as a function of density. Moving from the center of the slab to the surface, the condensate fraction was found to initially increase with decreasing density to a maximum value of 0.9 before decreasing. Long wavelength density correlations were observed in the static structure factor at the surface of the slab. Finally, a surface dispersion relation was calculated from imaginary-time density-density correlations.Comment: 8 pages, 5 figure

Elastic Constants of Quantum Solids by Path Integral Simulations

Two methods are proposed to evaluate the second-order elastic constants of quantum mechanically treated solids. One method is based on path-integral simulations in the (NVT) ensemble using an estimator for elastic constants. The other method is based on simulations in the (NpT) ensemble exploiting the relationship between strain fluctuations and elastic constants. The strengths and weaknesses of the methods are discussed thoroughly. We show how one can reduce statistical and systematic errors associated with so-called primitive estimators. The methods are then applied to solid argon at atmospheric pressures and solid helium 3 (hcp, fcc, and bcc) under varying pressures. Good agreement with available experimental data on elastic constants is found for helium 3. Predictions are made for the thermal expectation value of the kinetic energy of solid helium 3.Comment: 9 pages doublecolumn, 6 figures, submitted to PR

Path integral Monte Carlo simulation of charged particles in traps

This chapter is devoted to the computation of equilibrium (thermodynamic) properties of quantum systems. In particular, we will be interested in the situation where the interaction between particles is so strong that it cannot be treated as a small perturbation. For weakly coupled systems many efficient theoretical and computational techniques do exist. However, for strongly interacting systems such as nonideal gases or plasmas, strongly correlated electrons and so on, perturbation methods fail and alternative approaches are needed. Among them, an extremely successful one is the Monte Carlo (MC) method which we are going to consider in this chapter.Comment: 18 pages, based on talks on Hareaus school on computational methods, Greifswald, September 200