Effects of vertical confinement on gelation and sedimentation of colloids

We consider the sedimentation of a colloidal gel under confinement in the direction of gravity. The confinement allows us to compare directly experiments and computer simulations, for the same system size in the vertical direction. The confinement also leads to qualitatively different behaviour compared to bulk systems: in large systems gelation suppresses sedimentation, but for small systems sedimentation is enhanced relative to non-gelling suspensions, although the rate of sedimentation is reduced when the strength of the attraction between the colloids is strong. We map interaction parameters between a model experimental system (observed in real space) and computer simulations. Remarkably, we find that when simulating the system using Brownian dynamics in which hydrodynamic interactions between the particles are neglected, we find that sedimentation occurs on the same timescale as the experiments, however the thickness of the "arms" of the gel is rather larger in the experiments, compared with the simulations. An analysis of local structure in the simulations showed similar behaviour to gelation in the absence of gravity

Optimising self-assembly through time-dependent interactions

We demonstrate a simple method by which time-dependent interactions can be exploited to improve self-assembly in colloidal systems. We apply this method to two systems: a model colloid with short-ranged attractive potentials that undergoes crystallisation, and a schematic model of cluster growth. The method is based on initially strong bonds between particles, to accelerate nucleation, followed by a stage with weaker bonds, to promote growth of high-quality assembled structures. We track the growth of clusters during assembly, which reveals insight into effects of multiple nucleation events, and of competition between the growth of clusters with different properties.Comment: 13 page

Group-based exercise for Parkinson’s: a qualitative study of participants and partners’ perceptions of an exercise class delivered through a community-university collaboration

Background Community-based exercise programmes (CBEPs) offer a practical and viable approach to providing people with Parkinson's disease (PwP) the opportunity to exercise as an ancillary therapeutic benefit to pharmacological management. This study explores the perceptions of exercising participants (PwP) and non-participating partners involved in an exercise class delivered through a community-university partnership. Methods Two separate focus group discussions were conducted: one with class participants (PwP: n = 7, H&Y scale I to III), and the other with non-participating partners of PwP (n = 4). Results Thematic analysis of the data identified that a range of physical, psychological and social factors were perceived to influence engagement: (1) actively taking control, (2) exercise is medicine for the mind and body, and (3) a community working together to promote exercise for parkinson's. Participants and partners felt that the support from the group, including the instructors and student volunteers, empowered and supported PwP to proactively self-manage their health, enjoy exercise in an inclusive group setting, and develop strong social connections with others in the local Parkinson's community. Support to exercise from healthcare professionals was identified as both an enabler and barrier to participation. Conclusions This study underscores the significance of a community-university partnership as a complementary therapeutic approach for PwP. It also provides critical reflections on its sustainability, including implications for how exercise is considered as medicine for PwP. Additionally, it offers practical recommendations to galvanise community participation and provide inclusive and viable exercise opportunities for PwP

Group-based exercise for Parkinson’s: a qualitative study of participants and partners’ perceptions of an exercise class delivered through a community-university collaboration

Background Community-based exercise programmes (CBEPs) offer a practical and viable approach to providing people with Parkinson's disease (PwP) the opportunity to exercise as an ancillary therapeutic benefit to pharmacological management. This study explores the perceptions of exercising participants (PwP) and non-participating partners involved in an exercise class delivered through a community-university partnership. Methods Two separate focus group discussions were conducted: one with class participants (PwP: n = 7, H&Y scale I to III), and the other with non-participating partners of PwP (n = 4). Results Thematic analysis of the data identified that a range of physical, psychological and social factors were perceived to influence engagement: (1) actively taking control, (2) exercise is medicine for the mind and body, and (3) a community working together to promote exercise for parkinson's. Participants and partners felt that the support from the group, including the instructors and student volunteers, empowered and supported PwP to proactively self-manage their health, enjoy exercise in an inclusive group setting, and develop strong social connections with others in the local Parkinson's community. Support to exercise from healthcare professionals was identified as both an enabler and barrier to participation. Conclusions This study underscores the significance of a community-university partnership as a complementary therapeutic approach for PwP. It also provides critical reflections on its sustainability, including implications for how exercise is considered as medicine for PwP. Additionally, it offers practical recommendations to galvanise community participation and provide inclusive and viable exercise opportunities for PwP

Test-retest reliability of a 30-minute fixed perceived effort cycling exercise

Purpose: Using exercise protocols at a fixed rating of perceived effort (RPE) is a useful method for exploring the psychophysical influences on exercise performance. However, studies that have employed this protocol have arbitrarily selected RPE values without considering how these values correspond to exercise intensity thresholds and domains. Therefore, aligning RPE intensities with established physiological thresholds seems more appropriate, although the reliability of this method has not been assessed. Methods: Eight recreationally active cyclists completed two identical ramped incremental trials on a cycle ergometer to identify gas exchange threshold (GET). A linear regression model plotted RPE responses during this test alongside gas parameters to establish an RPE corresponding to GET (RPEGET) and 15% above GET (RPE+15%GET). Participants then completed three trials at each intensity, in which performance, physiological, and psychological measures were averaged into five-minute time zone (TZ) intervals and 30-minute ‘overall’ averages. Data were assessed for reliability using intraclass correlation coefficients (ICC) and accompanying standard error measurements (SEM), 95% confidence intervals, and coefficient of variations (CoV). Results: All performance and gas parameters showed excellent levels of test-retest reliability (ICCs = >.900) across both intensities. Performance, gas-related measures, and heart rate averaged over the entire 30-minute exercise demonstrated good intra-individual reliability (CoV = <5%). Conclusion: Recreationally active cyclists can reliably replicate fixed perceived effort exercise across multiple visits when RPE is aligned to physiological thresholds. Some evidence suggests that exercise at RPE+15%GET is more reliable than RPEGET

Radiological and clinical features of vein of Galen malformations.

BackgroundVein of Galen malformations (VOGMs) are rare and complex congenital arteriovenous fistulas. The clinical and radiological features of VOGMs and their relation to clinical outcomes are not fully characterized.ObjectiveTo examine the clinical and radiological features of VOGMs and the predictors of outcome in patients.MethodsWe retrospectively reviewed the available imaging and medical records of all patients with VOGMs treated at the University of California, San Francisco between 1986 and 2013. Radiological and clinical features were identified. We applied the modified Rankin Scale to determine functional outcome by chart review. Predictors of outcome were assessed by χ(2) analyses.ResultsForty-one cases were confirmed as VOGM. Most patients (78%) had been diagnosed with VOGM in the first year of life. Age at treatment was bimodally distributed, with predominantly urgent embolization at &lt;10 days of age and elective embolization after 1 year of age. Patients commonly presented with hydrocephalus (65.9%) and congestive heart failure (61.0%). Mixed-type (31.7%) VOGM was more common in our cohort than purely mural (29.3%) or choroidal (26.8%) types. The most common feeding arteries were the choroidal and posterior cerebral arteries. Transarterial embolization with coils was the most common technique used to treat VOGMs at our institution. Functional outcome was normal or only mildly disabled in 50% of the cases at last follow-up (median=3 years, range=0-23 years). Younger age at first diagnosis, congestive heart failure, and seizures were predictive of adverse clinical outcome. The survival rate in our sample was 78.0% and complete thrombosis of the VOGM was achieved in 62.5% of patients.ConclusionsVOGMs continue to be challenging to treat and manage. Nonetheless, endovascular approaches to treatment are continuing to be refined and improved, with increasing success. The neurodevelopmental outcomes of affected children whose VOGMs are treated may be good in many cases

Analysis of western lowland gorilla (Gorilla gorilla gorilla) specific Alu repeats

Background: Research into great ape genomes has revealed widely divergent activity levels over time for Alu elements. However, the diversity of this mobile element family in the genome of the western lowland gorilla has previously been uncharacterized. Alu elements are primate-specific short interspersed elements that have been used as phylogenetic and population genetic markers for more than two decades. Alu elements are present at high copy number in the genomes of all primates surveyed thus far. The AluY subfamily and its derivatives have been recognized as the evolutionarily youngest Alu subfamily in the Old World primate lineage. Results: Here we use a combination of computational and wet-bench laboratory methods to assess and catalog AluY subfamily activity level and composition in the western lowland gorilla genome (gorGor3.1). A total of 1,075 independent AluY insertions were identified and computationally divided into 10 subfamilies, with the largest number of gorilla-specific elements assigned to the canonical AluY subfamily. Conclusions: The retrotransposition activity level appears to be significantly lower than that seen in the human and chimpanzee lineages, while higher than that seen in orangutan genomes, indicative of differential Alu amplification in the western lowland gorilla lineage as compared to other Homininae. © 2013 McLain et al.; licensee BioMed Central Ltd