Effects of wall compliance on the laminar–turbulent transition of torsional Couette flow

Torsional Couette flow between a rotating disk and a stationary wall is studied experimentally. The surface of the disk is either rigid or covered with a compliant coating. The influence of wall compliance on characteristic flow instabilities and on the laminar–turbulent flow transition is investigated. Data obtained from analysing flow visualizations are discussed. It is found that wall compliance favours two of the three characteristic wave patterns associated with the transition process and broadens the parameter regime in which these patterns are observed. The results for the effects of wall compliance on the third pattern are inconclusive. However, the experiments indicate that the third pattern is not a primary constituent of the laminar–turbulent transition process of torsional Couette flow

Interacting Adaptive Processes with Different Timescales Underlie Short-Term Motor Learning

Multiple processes may contribute to motor skill acquisition, but it is thought that many of these processes require sleep or the passage of long periods of time ranging from several hours to many days or weeks. Here we demonstrate that within a timescale of minutes, two distinct fast-acting processes drive motor adaptation. One process responds weakly to error but retains information well, whereas the other responds strongly but has poor retention. This two-state learning system makes the surprising prediction of spontaneous recovery (or adaptation rebound) if error feedback is clamped at zero following an adaptation-extinction training episode. We used a novel paradigm to experimentally confirm this prediction in human motor learning of reaching, and we show that the interaction between the learning processes in this simple two-state system provides a unifying explanation for several different, apparently unrelated, phenomena in motor adaptation including savings, anterograde interference, spontaneous recovery, and rapid unlearning. Our results suggest that motor adaptation depends on at least two distinct neural systems that have different sensitivity to error and retain information at different rates

How to restore the Tropical Peat Swamp Forest in Aceh Province, Indonesia

This study aims to describe the condition of Tripa Peat Swamp Forest (TPSF) in the Province of Aceh Indonesia that has been converted from forest to oil palm plantation and mixed farms. The results showed that the degradation of the peat soil and the environment have occurred in the TPSF. Degradation of peat is characterized by the occurrence of changes in water holding capacity and changes in chemical and physical properties of soil. Environmental degradation is characterized by changes in groundwater levels and land subsidence. TPSF restoration efforts can be carried out in accordance with the directives of land use and land conservation and water managemen

A coupled drug kinetics-cell cycle model to analyse the response of human cells to intervention by topotecan

A model describing the response of the growth of single human cells in the absence and presence of the anti-cancer agent topotecan (TPT) is presented. The model includes a novel coupling of both the kinetics of TPT and cell cycle responses to the agent. By linking the models in this way, rather than using separate (disjoint) approaches, it is possible to illustrate how the drug perturbs the cell cycle. The model is compared to experimental in vitro cell cycle response data (comprising single cell descriptors for molecular and behavioural events), showing good qualitative agreement for a range of TPT dose levels

Association of an ACE Gene Polymorphism with Cardiovascular Determinants of Physical Performance in Healthy Iranian Men

Background: Physical performance phenotypes are formed by the interaction of genetic and environmental factors, and gene polymorphisms can influence physical and athletic abilities. An ACE gene insertion/deletion (I/D) polymorphism has been reported to influence physical performance, but its mechanism remains controversial.Methods: The frequency of this polymorphism in 146 healthy Iranian males was determined. Then, the associations between different ACE genotypes with physical performance factors were investigated for 43 of the 146 participants.Results: The frequencies of DD, ID and II genotypes were 38.5%, 41.5%, and 20%, respectively. Although there were no significant associations between the ACE polymorphisms and physical performance factors, the pulse pressure amplification, post-exercise heart rate, and resting heart rate were significantly different between variants with and without the I allele (P=0.02, 0.04, and 0.05, respectively). Furthermore, the ACE polymorphism was a significant predictor of exercise endurance and ventricular function in multivariate analyses (P<0.05).Conclusions: The ACE polymorphism correlated with cardiovascular determinants of physical performance, rather than musculoskeletal factors. Therefore, the ACE I/D polymorphism could not be utilized as a singular genetic biomarker for the assessment of physical performance in the Iranian population. However, a combination of genetic and cardiovascular biomarkers may determine physical performance capacities

Association of an ACE Gene Polymorphism with Cardiovascular Determinants of Physical Performance in Healthy Iranian Men

Background: Physical performance phenotypes are formed by the interaction of genetic and environmental factors, and gene polymorphisms can influence physical and athletic abilities. An ACE gene insertion/deletion (I/D) polymorphism has been reported to influence physical performance, but its mechanism remains controversial.Methods: The frequency of this polymorphism in 146 healthy Iranian males was determined. Then, the associations between different ACE genotypes with physical performance factors were investigated for 43 of the 146 participants.Results: The frequencies of DD, ID and II genotypes were 38.5%, 41.5%, and 20%, respectively. Although there were no significant associations between the ACE polymorphisms and physical performance factors, the pulse pressure amplification, post-exercise heart rate, and resting heart rate were significantly different between variants with and without the I allele (P=0.02, 0.04, and 0.05, respectively). Furthermore, the ACE polymorphism was a significant predictor of exercise endurance and ventricular function in multivariate analyses (P<0.05).Conclusions: The ACE polymorphism correlated with cardiovascular determinants of physical performance, rather than musculoskeletal factors. Therefore, the ACE I/D polymorphism could not be utilized as a singular genetic biomarker for the assessment of physical performance in the Iranian population. However, a combination of genetic and cardiovascular biomarkers may determine physical performance capacities

Self-organization of an optomagnetic CoFe2O4-ZnS nanocomposite : preparation and characterization

We report an advanced method for the self-organization of an optomagnetic nanocomposite composed of both fluorescent clusters (ZnS quantum dots, QDs) and magnetic nanoparticles (CoFe2O4). ZnS nanocrystals were prepared via an aqueous method at different temperatures (25, 50, 75, and 100 degrees C). Their structural, optical and chemical properties were comprehensively characterized by X-ray diffraction (XRD), UV-vis, photoluminescence (PL) spectroscopy, scanning electron microscopy (SEM), dynamic light scattering (DLS), transmission electron microscopy (TEM), and infrared spectroscopy (FT-IR). The highest PL intensity was observed for the cubic ZnS nanoparticles synthesized at 75 degrees C which were then stabilized electrosterically using thioglycolic acid. The photophysical analysis of the capped QDs with a particle size in the range 9-25 nm revealed that the emission intensity and the optical band gap increases compared to uncapped nanocrystals (3.88 to 4.02 eV). These band gaps are wider than that of bulk ZnS resulting from the quantum confinement effect. Magnetic nanoparticles were synthesized via a co-precipitation route and a sol-gel process was used to form the functionalized, silica-coated CoFe2O4. Finally, thiol coordination was used for binding the QDs to the surface of the magnetic nanoparticles. The fluorescence intensity and magnetic properties of the nanocomposites are related to the ratio of ZnS and CoFe2O4. An optomagnetic nanocomposite with small size (12-45 nm), acceptable saturation magnetization (about 6.7 emu g(-1)), and satisfactory luminescence characteristics was successfully synthesized. These systems are promising candidates for biological and photocatalytic applications

The prevalence of metabolic syndrome increases with serum hs-CRP concentration in individuals without a history of cardiovascular disease: a report from a large Persian cohort

BACKGROUND: Metabolic syndrome (MetS) is defined by a clustering of cardiovascular (CV) risk factors and is associated with a heightened inflammatory state. A raised serum high-sensitivity C-reactive protein (hs-CRP), a marker of inflammation, is also known to associate with CV risk. We have investigated the relationship between the presence of MetS and serum hs-CRP concentration in a large representative Persian population cohort without a history of cardiovascular disease (CVD). METHODS: The MASHAD study population cohort comprised 9 778 subjects, who were recruited from the city of Mashhad, Iran, between 2007 and 2008. Several cardiovascular risk factors were measured in this population without CVD. Individuals were categorized into quartiles of serum hs-CRP concentration: 1st quartile - 0.72 (0.59-0.85) [median (range)] mg/L, 2nd quartile - 1.30 (1.14-1.4) mg/L, 3rd quartile - 2.29 (1.92-2.81) mg/L and 4th quartile - 6.63 (4.61-11.95) mg/L respectively. The prevalence of MetS in each quartile was determined using either International Diabetes Federation (IDF) or Adult Treatment Panel III (ATPIII) criteria. RESULTS: The prevalence of MetS was highest in the 4th quartile for serum hs-CRP [1220 subjects (50.0%)], and significantly higher than that in the 1st quartile (reference group) [634 subjects (25.9%)] (p<0.001). A positive smoking habit [OR, 1.47 (1.26-1.70), p<0.001] and the presence of either MetS-IDF [OR, 1.35 (1.18-1.55), p<0.001] or Mets-ATPIII [OR, 1.40 (1.18-1.50), p<0.001] were strong predictors of a 4th quartile for serum hs-CRP concentration. CONCLUSIONS: There was a significant association between high levels of serum hs-CRP and the presence of MetS among individuals without a history of CVD in our Persian cohort