5,163 research outputs found
Thermodynamics of nano-spheres encapsulated in virus capsids
We investigate the thermodynamics of complexation of functionalized charged
nano-spheres with viral proteins. The physics of this problem is governed by
electrostatic interaction between the proteins and the nano-sphere cores
(screened by salt ions), but also by configurational degrees of freedom of the
charged protein N-tails. We approach the problem by constructing an appropriate
complexation free energy functional. On the basis of both numerical and
analytical studies of this functional we construct the phase diagram for the
assembly which contains the information on the assembled structures that appear
in the thermodynamical equilibrium, depending on the size and surface charge
density of the nano-sphere cores. We show that both the nano-sphere core charge
as well as its radius determine the size of the capsid that forms around the
core.Comment: Submitte
Kinetics of viral self-assembly: the role of ss RNA antenna
A big class of viruses self-assemble from a large number of identical capsid
proteins with long flexible N-terminal tails and ss RNA. We study the role of
the strong Coulomb interaction of positive N-terminal tails with ss RNA in the
kinetics of the in vitro virus self-assembly. Capsid proteins stick to
unassembled chain of ss RNA (which we call "antenna") and slide on it towards
the assembly site. We show that at excess of capsid proteins such
one-dimensional diffusion accelerates self-assembly more than ten times. On the
other hand at excess of ss RNA, antenna slows self-assembly down. Several
experiments are proposed to verify the role of ss RNA antenna.Comment: 4 pages, 3 figures, several experiments are proposed, a new idea of
experiment is adde
Understanding exercise behavior and drop-out through metamotivational dominance, exercise identity and motives
Despite literature exploring interventions and strategies to encourage exercise adoption and maintenance, the dropout rate of irregular exercisers, particularly within the first six months of adoption, continues to reduce the effectiveness of such interventions. Whilst a body of literature exists exploring the dropout profile of clinical patients, less is known about the psychological and theoretical differences that discriminate exercise behavior and that could be indicative of susceptibility to dropout in the general population. Our study examines whether the metamotivational constructs of reversal theory (Apter, 1989), exercise motives, and exercise identity can discriminate between males’ and females’ exercise behavior, defined in relation to length of exercise participation, consistency (frequency of previous dropout) and the main type of exercise engaged in. We created an online survey to which 973 participants responded. We used MANOVA to determine whether exercise length, consistency, or type resulted in significant differences in levels of outcome variables. Where we identified significant effects, we employed discriminant function analysis to determine whether and how the dependent variables were able to discriminate between groupings. Results indicated that differing profiles of exercise identity, metamotivational dominance, and motives for exercise could discriminate between females and males who had been exercising for different lengths of time, with different levels of exercise consistency and differing types of main exercise. Our findings indicate that specific groupings may highlight individuals who are vulnerable to dropout so that strategies can be tailored more effectively for these individuals and support more appropriate strategies to develop internalized motivation
Notorious places: image, reputation, stigma: the role of newspapers in area reputations for social housing estates
This paper reviews work in several disciplines to distinguish between image, reputation and stigma. It also shows that there has been little research on the process by which area reputations are established and sustained through transmission processes. This paper reports on research into the portrayal of two social housing estates in the printed media over an extended period of time (14 years). It was found that negative and mixed coverage of the estates dominated, with the amount of positive coverage being very small. By examining the way in which dominant themes were used by newspapers in respect of each estate, questions are raised about the mode of operation of the press and the communities' collective right to challenge this. By identifying the way regeneration stories are covered and the nature of the content of positive stories, lessons are drawn for programmes of area transformation. The need for social regeneration activities is identified as an important ingredient for changing deprived-area reputations
A method for achieving prolonged nutrient limited growth of Neurospora mycelium.
A method for achieving prolonged nutrient-limited growth of Neurospora mycelium
Density waves theory of the capsid structure of small icosahedral viruses
We apply Landau theory of crystallization to explain and to classify the
capsid structures of small viruses with spherical topology and icosahedral
symmetry. We develop an explicit method which predicts the positions of centers
of mass for the proteins constituting viral capsid shell. Corresponding density
distribution function which generates the positions has universal form without
any fitting parameter. The theory describes in a uniform way both the
structures satisfying the well-known Caspar and Klug geometrical model for
capsid construction and those violating it. The quasiequivalence of protein
environments in viral capsid and peculiarities of the assembly thermodynamics
are also discussed.Comment: 8 pages, 3 figur
Strong interaction between electrons and collective excitations in multiband superconductor MgB2
We use a tunable laser ARPES to study the electronic properties of the
prototypical multiband BCS superconductor MgB2. Our data reveal a strong
renormalization of the dispersion (kink) at ~65 meV, which is caused by
coupling of electrons to the E2g phonon mode. In contrast to cuprates, the 65
meV kink in MgB2 does not change significantly across Tc. More interestingly,
we observe strong coupling to a second, lower energy collective mode at binding
energy of 10 meV. This excitation vanishes above Tc and is likely a signature
of the elusive Leggett mode.Comment: 10 fig
Homophilic binding of PTP mu, a receptor-type protein tyrosine phosphatase, can mediate cell-cell aggregation
The receptor-like protein tyrosine phosphatase, PTPmu, displays structural similarity to cell-cell adhesion molecules of the immunoglobulin superfamily. We have investigated the ability of human PTPmu to function in such a capacity. Expression of PTPmu, with or without the PTPase domains, by recombinant baculovirus infection of Sf9 cells induced their aggregation. However, neither a chimeric form of PTPmu, containing the extracellular and transmembrane segments of the EGF receptor and the intracellular segment of PTPmu, nor the intracellular segment of PTPmu expressed as a soluble protein induced aggregation. PTPmu mediates aggregation via a homophilic mechanism, as judged by lack of incorporation of uninfected Sf9 cells into aggregates of PTPmu-expressing cells. Homophilic binding has been demonstrated between PTPmu-coated fluorescent beads (Covaspheres) and endogenously expressed PTPmu on MvLu cells. Additionally the PTPmu-coated beads specifically bound to a bacterially expressed glutathione-S-transferase fusion protein containing the extracellular segment of PTPmu (GST/PTPmu) adsorbed to petri dishes. Covaspheres coated with the GST/PTPmu fusion protein aggregated in vitro and also bound to PTPmu expressed endogenously on MvLu cells. These results suggest that the ligand for this transmembrane PTPase is another PTPmu molecule on an adjacent cell. Thus homophilic binding interactions may be an important component of the function of PTPmu in vivo
Recommended from our members
A study protocol for a randomised crossover study evaluating the effect of diets differing in carbohydrate quality on ileal content and appetite regulation in healthy humans
A major component of the digesta reaching the colon from the distal ileum is carbohydrate. This carbohydrate is subject to microbial fermentation and can radically change bacterial populations in the colon and the metabolites they produce, particularly short-chain fatty acids (SCFA). However, very little is currently known about the forms and levels of carbohydrate in the ileum and the composition of the ileal microbiota in humans. Most of our current understanding of carbohydrate that is not absorbed by the small intestine comes from ileostomy models, which may not reflect the physiology of an intact gastrointestinal tract. We will investigate how ileal content changes depending on diet using a randomised crossover study in healthy humans. Participants will be inpatients at the research facility for three separate 4-day visits. During each visit, participants will consume one of three diets, which differ in carbohydrate quality: 1) low-fibre refined diet; 2) high-fibre diet with intact cellular structures; 3) high-fibre diet where the cellular structures have been disrupted (e.g. milling, blending). On day 1, a nasoenteric tube will be placed into the distal ileum and its position confirmed under fluoroscopy. Ileal samples will be collected via the nasoenteric tube and metabolically profiled, which will determine the amount and type of carbohydrate present, and the composition of the ileal microbiota will be measured. Blood samples will be collected to assess circulating hormones and metabolites. Stool samples will be collected to assess faecal microbiota composition. Subjective appetite measures will be collected using visual analogue scales. Breath hydrogen will be measured in real-time as a marker of intestinal fermentation. Finally, an continuous fermentation model will be inoculated with ileal fluid in order to understand the shift in microbial composition and SCFA produced in the colon following the different diets. ISRCTN11327221. [Abstract copyright: Copyright: © 2019 Byrne CS et al.
Damned if they do, damned if they don't: negotiating the tricky context of anti-social behaviour and keeping safe in disadvantaged urban neighbourhoods
Young people's relationship with anti-social behaviour (ASB) is complicated. While their behaviours are often stereotyped as anti-social (e.g. ‘hanging about’), they also experience ASB in their neighbourhood. In this study, we explore young people's own perspectives on ASB, comparing results from ‘go-along’ interviews and focus groups conducted in disadvantaged neighbourhoods in Glasgow, Scotland. This article discusses how young people's everyday experience of ASB was contextualised by social factors such as cultural stereotyping of marginalised groups, poor social connectivity and spatial marginalisation within their neighbourhood. Furthermore, we found that these social factors were mutually reinforcing and interacted in a way that appeared to leave young people in a ‘no-win’ situation regarding their association with ASB. Participation in ASB and attempts to avoid such involvement were seen to involve negative consequences: participation could entail violence and spatial restrictions linked to territoriality, but avoidance could lead to being ostracised from their peer group. Regardless of involvement, young people felt that adults stereotyped them as anti-social. Our findings therefore provide support for policies and interventions aimed at reducing ASB (perpetrated by residents of all ages); in part by better ensuring that young people have a clear incentive for avoiding such behaviours
- …