Conformations of dendrimers in dilute solution

Conformations of isolated homo- dendrimers of G=1-7 generations with D=1-6 spacers have been studied in the good and poor solvents, as well as across the coil-to-globule transition, by means of a version of the Gaussian self-consistent (GSC) method and Monte Carlo (MC) simulation in continuous space based on the same coarse-grained model. The latter includes harmonic springs between connected monomers and the pair-wise Lennard-Jones potential with a hard core repulsion. The scaling law for the dendrimer size, the degrees of bond stretching and steric congestion, as well as the radial density, static structure factor, and asphericity have been analysed. It is also confirmed that while smaller dendrimers have a dense core, larger ones develop a hollow domain at some separation from the centre.Comment: RevTeX, 14 pages, 19 PS figures, Accepted for publication in J. Chem. Phy

Monte Carlo simulations of infinitely dilute solutions of amphiphilic diblock star copolymers

Single-chain Monte Carlo simulations of amphiphilic diblock star copolymers were carried out in continuous space using implicit solvents. Two distinct architectures were studied: stars with the hydrophobic blocks attached to the core, and stars with the polar blocks attached to the core, with all arms being of equal length. The ratio of the lengths of the hydrophobic block to the length of the polar block was varied from 0 to 1. Stars with 3, 6, 9 or 12 arms, each of length 10, 15, 25, 50, 75 and 100 Kuhn segments were analysed. Four distinct types of conformations were observed for these systems. These, apart from studying the snapshots from the simulations, have been quantitatively characterised in terms of the mean-squared radii of gyration, mean-squared distances of monomers from the centre-of-mass, asphericity indices, static scattering form factors in the Kratky representation as well as the intra-chain monomer-monomer radial distribution functions.Comment: 12 pages, 11 ps figures. Accepted for publication in J. Chem. Phy

Unintended Consequences of COVID-19 Non-Pharmaceutical Interventions (NPIs) for Population Health and Health Inequalities

Since the start of the COVID-19 pandemic in early 2020, governments around the world have adopted an array of measures intended to control the transmission of the SARS-CoV-2 virus, using both pharmaceutical and non-pharmaceutical interventions (NPIs). NPIs are public health interventions that do not rely on vaccines or medicines and include policies such as lockdowns, stay-at-home orders, school closures, and travel restrictions. Although the intention was to slow viral transmission, emerging research indicates that these NPIs have also had unintended consequences for other aspects of public health. Hence, we conducted a narrative review of studies investigating these unintended consequences of NPIs, with a particular emphasis on mental health and on lifestyle risk factors for non-communicable diseases (NCD): physical activity (PA), overweight and obesity, alcohol consumption, and tobacco smoking. We reviewed the scientific literature using combinations of search terms such as ‘COVID-190 , ‘pandemic’, ‘lockdowns’, ‘mental health’, ‘physical activity’, and ‘obesity’. NPIs were found to have considerable adverse consequences for mental health, physical activity, and overweight and obesity. The impacts on alcohol and tobacco consumption varied greatly within and between studies. The variability in consequences for different groups implies increased health inequalities by age, sex/gender, socioeconomic status, pre-existing lifestyle, and place of residence. In conclusion, a proper assessment of the use of NPIs in attempts to control the spread of the pandemic should be weighed against the potential adverse impacts on other aspects of public health. Our findings should also be of relevance for future pandemic preparedness and pandemic response teams

Intra-chain correlation functions and shapes of homopolymers with different architectures in dilute solution

We present results of Monte Carlo study of the monomer-monomer correlation functions, static structure factor and asphericity characteristics of a single homopolymer in the coil and globular states for three distinct architectures of the chain: ring, open and star. To rationalise the results we introduce the dimensionless correlation functions rescaled via the corresponding mean-squared distances between monomers. For flexible chains with some architectures these functions exhibit a large degree of universality by falling onto a single or several distinct master curves. In the repulsive regime, where a stretched exponential times a power law form (de Cloizeaux scaling) can be applied, the corresponding exponents $\delta$ and $\theta$ have been obtained. The exponent $\delta=1/\nu$ is found to be universal for flexible strongly repulsive coils and in agreement with the theoretical prediction from improved higher-order Borel-resummed renormalisation group calculations. The short-distance exponents $\theta_{\upsilon}$ of an open flexible chain are in a good agreement with the theoretical predictions in the strongly repulsive regime also. However, increasing the Kuhn length in relation to the monomer size leads to their fast cross-over towards the Gaussian behaviour. Likewise, a strong sensitivity of various exponents $\theta_{ij}$ on the stiffness of the chain, or on the number of arms in star polymers, is observed. The correlation functions in the globular state are found to have a more complicated oscillating behaviour and their degree of universality has been reviewed. Average shapes of the polymers in terms of the asphericity characteristics, as well as the universal behaviour in the static structure factors, have been also investigated.Comment: RevTeX 12 pages, 10 PS figures. Accepted by J. Chem. Phy

Designing an Educational Program to Promote Diversity and Student Engagement in Professional Advocacy (SEPA)

Little is understood about best educational strategies to engage diverse occupational therapy students in professional advocacy. The purpose of this research was to use design-based research (DBR) methods to design a novel educational intervention to promote professional engagement of diverse students over three subsequent years. This study used a pre/post design to design, implement, evaluate, and revise an educational program entitled “Student Engagement in Professional Advocacy” (SEPA). This manuscript reports on the first year of that study. The participants (N=27) were entry-level Master of Science occupational therapy students. The outcome measure was a survey measuring student knowledge, attitude, and participation specific to professional advocacy. All participants completed the pre and post surveys and participated in four SEPA educational modules. Significant differences were observed in pre and post scores in knowledge (p \u3c 0.0001), action (p= 0.004), and attitude (p=0.012). This suggests that SEPA was effective at increasing student knowledge of, attitudes toward, and participation in professional advocacy. Pearson correlation of domains revealed a strong positive association between knowledge and attitude (p= 0.0003), actions and attitude (p = 0.0018), and action and knowledge (p=0.0262). This indicates that educational programs promoting professional engagement should address knowledge and attitudes and provide opportunities for participation. Qualitative data provided additional information on how students integrated professional engagement into their identity as students, and practical feedback on how to improve the program. Study findings supported the use of SEPA to promote student professional engagement. Further research is indicated, including conducting additional iterations of the project to continue to refine SEPA

Ecological constraint mapping: understanding uutcome-limiting bottlenecks for improved environmental decision-making in marine and coastal environments

Despite genuine attempts, the history of marine and coastal ecosystem management is littered with examples of poor environmental, social and financial outcomes. Marine ecosystems are largely populated by species with open populations, and feature ecological processes that are driven by multiple, interwoven, dynamic causes and effects. This complexity limits the acquisition of relevant knowledge of habitat characteristics, species utilisation and ecosystem dynamics. The consequence of this lack of knowledge is uncertainty about the link between action taken and outcome achieved. Such uncertainty risks misdirected human and financial investment, and sometimes may even lead to perverse outcomes. Technological advances offer new data acquisition opportunities, but the diversity and complexity of the biological and ecological information needed to reduce uncertainty means the increase in knowledge will be slow unless it is undertaken in a structured and focussed way. We introduce “Ecological Constraint Mapping” – an approach that takes a “supply chain” point of view and focusses on identifying the principal factors that constrain life-history outcomes (success/productivity/resilience/fitness) for marine and coastal species, and ultimately the quality and resilience of the ecosystems they are components of, and the life-history supporting processes and values ecosystems provide. By providing a framework for the efficient development of actionable knowledge, Ecological Constraint Mapping can facilitate a move from paradigm-based to knowledge-informed decision-making on ecological issues. It is suitable for developing optimal solutions to a wide range of conservation and management problems, providing an organised framework that aligns with current perspectives on the complex nature of marine and coastal systems

Gene expression profiling reveals differential effects of sodium selenite, selenomethionine, and yeast-derived selenium in the mouse

The essential trace mineral selenium is an important determinant of oxidative stress susceptibility, with several studies showing an inverse relationship between selenium intake and cancer. Because different chemical forms of selenium have been reported to have varying bioactivity, there is a need for nutrigenomic studies that can comprehensively assess whether there are divergent effects at the molecular level. We examined the gene expression profiles associated with selenomethionine (SM), sodium selenite (SS), and yeast-derived selenium (YS) in the intestine, gastrocnemius, cerebral cortex, and liver of mice. Weanling mice were fed either a selenium-deficient (SD) diet (<0.01 mg/kg diet) or a diet supplemented with one of three selenium sources (1 mg/kg diet, as either SM, SS or YS) for 100 days. All forms of selenium were equally effective in activating standard measures of selenium status, including tissue selenium levels, expression of genes encoding selenoproteins (Gpx1 and Txnrd2), and increasing GPX1 enzyme activity. However, gene expression profiling revealed that SS and YS were similar (and distinct from SM) in both the expression pattern of individual genes and gene functional categories. Furthermore, only YS significantly reduced the expression of Gadd45b in all four tissues and also reduced GADD45B protein levels in liver. Taken together, these results show that gene expression profiling is a powerful technique capable of elucidating differences in the bioactivity of different forms of selenium