Neutron scattering and polymer dynamics

4 páginas, 4 figuras.-- El pdf del artículo es la versión post-print.Nowadays polymers are ubiquitous in our daily life because they are durable, cheap to produce, easy to process and exhibit very versatile and favorable mechanical properties. For example, depending on temperature or time the same polymer may be viscous, rubber elastic, very tough with high impact strength or even brittle. Polymers are composed of macromolecules which are built up by a large number monomer units linked together by covalent bonds. Due to this connectivity, the relevant processes driving the dynamics in polymers depend on the length scale of observation. While at typical inter- and intra-macromolecular length scales (≈ 10 Å and below) polymer dynamics display the universal features of glass-forming systems, at larger distances the macromolecular character of the polymer chains prevails –there, entropy and topological constraints (‘entanglements’) play the major role. Carbon and Hydrogen are in most cases the main constituents of polymers. Therefore, neutron scattering combined with isotopic substitution (H/D labeling) is an extremely well-suited technique to study the dynamical processes of polymeric materials at a molecular level. Motions of particular molecular groups or given polymer chains, e. g. in a polymer blend, can be selectively investigated by neutron scattering. However, the restricted dynamic window offered by this technique prevents a complete characterization of the complex polymer dynamics, including several multi-scale processes the characteristic times of which span over many orders of magnitude. The combination with other experimental techniques is, in most cases, essential to fully characterize the processes; in addition, the use of complementary MD-simulations has proved to be crucial for the interpretation of the neutron-scattering results.Peer reviewe

Health Behavior and Associated Factors in Young Adult Cancer Patients

Objectives: Having cancer in young adulthood increases the risk of adverse long-term health effects. These risks can be influenced by one’s health behavior (HB). The aim of this study is therefore to investigate the presence of health behavior in adolescents and young adults (AYAs) and to identify associated factors. Design: Young cancer patients (18–39 years old at time of diagnosis) were surveyed at baseline and 12 months later via online or as a paper-pencil version. Methods: A spectrum of indicators for HB was assessed via seven items from the Questionnaire of Multiple Health Behavior (MHB). Multiple linear regression analyses were conducted to determine factors associated with patients’ HB indicators. Results: Five-hundred and fourteen AYAs (75% women) reported the highest level of health-conscious behavior for “avoidance of consumption of nicotine,” “follow medical recommendations,” and “being considerate in road traffic.” Less health-conscious behavior was reported for “keeping an appropriate and balanced diet” and “physical activity.” Significant improvements from baseline to the follow-up were observed for “regularly attending health screening” (Hedges’ g = 0.44). The analyzed factors explained up to 10% of the HB indicators. Women reported significantly more healthconscious behavior than men in four out of seven HB indicators. Higher quality of life (QoL) was associated with more health behavior in three out of seven HB indicators. Conclusion: Findings show a predominantly health-conscious lifestyle in AYA cancer patients, though we also found harmful behavior which needs to be better approached—e.g., through improving AYAs’ health education. AYA men should be particularly targeted in specific prevention and health promotion measures. Future work should identify other factors associated with HB to evaluate targets for intervention

Non-invasive vagus nerve stimulation in epilepsy patients enhances cooperative behavior in the prisoner's dilemma task

The vagus nerve constitutes a key link between the autonomic and the central nervous system. Previous studies provide evidence for the impact of vagal activity on distinct cognitive processes including functions related to social cognition. Recent studies in animals and humans show that vagus nerve stimulation is associated with enhanced reward-seeking and dopamine-release in the brain. Social interaction recruits similar brain circuits to reward processing. We hypothesize that vagus nerve stimulation (VNS) boosts rewarding aspects of social behavior and compare the impact of transcutaneous VNS (tVNS) and sham stimulation on social interaction in 19 epilepsy patients in a double-blind pseudo-randomized study with cross-over design. Using a well-established paradigm, i.e., the prisoner's dilemma, we investigate effects of stimulation on cooperative behavior, as well as interactions of stimulation effects with patient characteristics. A repeated-measures ANOVA and a linear mixed-effects model provide converging evidence that tVNS boosts cooperation. Post-hoc correlations reveal that this effect varies as a function of neuroticism, a personality trait linked to the dopaminergic system. Behavioral modeling indicates that tVNS induces a behavioral starting bias towards cooperation, which is independent of the decision process. This study provides evidence for the causal influence of vagus nerve activity on social interaction

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Health Behavior and Associated Factors in Young Adult Cancer Patients

Objectives: Having cancer in young adulthood increases the risk of adverse long-term health effects. These risks can be influenced by one’s health behavior (HB). The aim of this study is therefore to investigate the presence of health behavior in adolescents and young adults (AYAs) and to identify associated factors. Design: Young cancer patients (18–39 years old at time of diagnosis) were surveyed at baseline and 12 months later via online or as a paper-pencil version. Methods: A spectrum of indicators for HB was assessed via seven items from the Questionnaire of Multiple Health Behavior (MHB). Multiple linear regression analyses were conducted to determine factors associated with patients’ HB indicators. Results: Five-hundred and fourteen AYAs (75% women) reported the highest level of health-conscious behavior for “avoidance of consumption of nicotine,” “follow medical recommendations,” and “being considerate in road traffic.” Less health-conscious behavior was reported for “keeping an appropriate and balanced diet” and “physical activity.” Significant improvements from baseline to the follow-up were observed for “regularly attending health screening” (Hedges’ g = 0.44). The analyzed factors explained up to 10% of the HB indicators. Women reported significantly more healthconscious behavior than men in four out of seven HB indicators. Higher quality of life (QoL) was associated with more health behavior in three out of seven HB indicators. Conclusion: Findings show a predominantly health-conscious lifestyle in AYA cancer patients, though we also found harmful behavior which needs to be better approached—e.g., through improving AYAs’ health education. AYA men should be particularly targeted in specific prevention and health promotion measures. Future work should identify other factors associated with HB to evaluate targets for intervention

Health Behavior and Associated Factors in Young Adult Cancer Patients

Objectives: Having cancer in young adulthood increases the risk of adverse long-term health effects. These risks can be influenced by one’s health behavior (HB). The aim of this study is therefore to investigate the presence of health behavior in adolescents and young adults (AYAs) and to identify associated factors. Design: Young cancer patients (18–39 years old at time of diagnosis) were surveyed at baseline and 12 months later via online or as a paper-pencil version. Methods: A spectrum of indicators for HB was assessed via seven items from the Questionnaire of Multiple Health Behavior (MHB). Multiple linear regression analyses were conducted to determine factors associated with patients’ HB indicators. Results: Five-hundred and fourteen AYAs (75% women) reported the highest level of health-conscious behavior for “avoidance of consumption of nicotine,” “follow medical recommendations,” and “being considerate in road traffic.” Less health-conscious behavior was reported for “keeping an appropriate and balanced diet” and “physical activity.” Significant improvements from baseline to the follow-up were observed for “regularly attending health screening” (Hedges’ g = 0.44). The analyzed factors explained up to 10% of the HB indicators. Women reported significantly more healthconscious behavior than men in four out of seven HB indicators. Higher quality of life (QoL) was associated with more health behavior in three out of seven HB indicators. Conclusion: Findings show a predominantly health-conscious lifestyle in AYA cancer patients, though we also found harmful behavior which needs to be better approached—e.g., through improving AYAs’ health education. AYA men should be particularly targeted in specific prevention and health promotion measures. Future work should identify other factors associated with HB to evaluate targets for intervention