Alexander representation of tangles

A tangle is an oriented 1-submanifold of the cylinder whose endpoints lie on the two disks in the boundary of the cylinder. Using an algebraic tool developed by Lescop, we extend the Burau representation of braids to a functor from the category of oriented tangles to the category of Z[t,t^{-1}]-modules. For (1,1)-tangles (i.e., tangles with one endpoint on each disk) this invariant coincides with the Alexander polynomial of the link obtained by taking the closure of the tangle. We use the notion of plat position of a tangle to give a constructive proof of invariance in this case.Comment: 13 pages, 5 figure

Efficacy of an intensive outpatient rehabilitation program in alcoholism: Predictors of outcome 6 months after treatment

Treatment of alcohol-dependent patients was primarily focused on inpatient settings in the past decades. The efficacy of these treatment programs has been evaluated in several studies and proven to be sufficient. However, with regard to the increasing costs in public healthcare systems, questions about alternative treatment strategies have been raised. Meanwhile, there is growing evidence that outpatient treatment might be comparably effective as inpatient treatment, at least for subgroups of alcohol dependents. On that background, the present study aimed to evaluate the efficacy of a high-structured outpatient treatment program in 103 alcohol-dependent patients. 74 patients (72%) terminated the outpatient treatment regularly. At 6 months' follow-up, 95% patients were successfully located and personally re-interviewed. Analyses revealed that 65 patients (64%) were abstinent at the 6-month follow-up evaluation and 37 patients ( 36%) were judged to be non-abstinent. Pretreatment variables which were found to have a negative impact (non-abstinence) on the 6-month outcome after treatment were a higher severity of alcohol dependence measured by a longer duration of alcohol dependence, a higher number of prior treatments and a stronger alcohol craving (measured by the Obsessive Compulsive Drinking Scale). Further patients with a higher degree of psychopathology measured by the Beck Depression Inventory (depression) and State-Trait Anxiety Inventory (anxiety) relapsed more often. In summary, results of this study indicate a favorable outcome of socially stable alcohol-dependent patients and patients with a lower degree of depression, anxiety and craving in an intensive outpatient rehabilitation program

Neural correlates of enhanced visual short-term memory for angry faces: An fMRI study

Copyright: © 2008 Jackson et al.Background: Fluid and effective social communication requires that both face identity and emotional expression information are encoded and maintained in visual short-term memory (VSTM) to enable a coherent, ongoing picture of the world and its players. This appears to be of particular evolutionary importance when confronted with potentially threatening displays of emotion - previous research has shown better VSTM for angry versus happy or neutral face identities.Methodology/Principal Findings: Using functional magnetic resonance imaging, here we investigated the neural correlates of this angry face benefit in VSTM. Participants were shown between one and four to-be-remembered angry, happy, or neutral faces, and after a short retention delay they stated whether a single probe face had been present or not in the previous display. All faces in any one display expressed the same emotion, and the task required memory for face identity. We find enhanced VSTM for angry face identities and describe the right hemisphere brain network underpinning this effect, which involves the globus pallidus, superior temporal sulcus, and frontal lobe. Increased activity in the globus pallidus was significantly correlated with the angry benefit in VSTM. Areas modulated by emotion were distinct from those modulated by memory load.Conclusions/Significance: Our results provide evidence for a key role of the basal ganglia as an interface between emotion and cognition, supported by a frontal, temporal, and occipital network.The authors were supported by a Wellcome Trust grant (grant number 077185/Z/05/Z) and by BBSRC (UK) grant BBS/B/16178

Error and attack tolerance of complex networks

Many complex systems, such as communication networks, display a surprising degree of robustness: while key components regularly malfunction, local failures rarely lead to the loss of the global information-carrying ability of the network. The stability of these complex systems is often attributed to the redundant wiring of the functional web defined by the systems' components. In this paper we demonstrate that error tolerance is not shared by all redundant systems, but it is displayed only by a class of inhomogeneously wired networks, called scale-free networks. We find that scale-free networks, describing a number of systems, such as the World Wide Web, Internet, social networks or a cell, display an unexpected degree of robustness, the ability of their nodes to communicate being unaffected by even unrealistically high failure rates. However, error tolerance comes at a high price: these networks are extremely vulnerable to attacks, i.e. to the selection and removal of a few nodes that play the most important role in assuring the network's connectivity.Comment: 14 pages, 4 figures, Late

Negative emotions in informal feedback: The benefits of disappointment and drawbacks of anger

Using the emotions as social information (EASI) model, this study investigated the emotional, attitudinal and behavioral reactions to failure feedback by manipulating negative emotional displays (angry, disappointed or none) and the position level and relational distance of the feedback source. Undergraduate students (N = 260) responded to an organizational failure feedback vignette and completed a subsequent performance task. Results demonstrated that guilt was the complementary emotional experience following displays of disappointment, while reciprocal anger followed displays of anger. These emotional reactions served as important mediators between the emotional displays paired with the feedback message and participant responses of social behaviors, creative task performance and perceptions of the feedback source. In addition, our findings indicated that negative emotions can have positive organizational and interpersonal outcomes. Guilt in response to disappointed displays resulted in beneficial behaviors and attitudes, while anger in response to angry displays was socially detrimental. The emotion displayed during feedback provision also served as a consistent contextual factor that did not interact with the position level or relational distance of the feedback source to impact behavioral and attitudinal reactions. Overall, this study indicates that discrete negative emotions have unique social-functional properties that require further investigation.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

Mindfulness based interventions in multiple sclerosis: a systematic review

<b>Background</b> Multiple sclerosis (MS) is a stressful condition; depression, anxiety, pain and fatigue are all common problems. Mindfulness based interventions (MBIs) mitigate stress and prevent relapse in depression and are increasingly being used in healthcare. However, there are currently no systematic reviews of MBIs in people with MS. This review aims to evaluate the effectiveness of MBIs in people with MS.<p></p> <b>Methods</b> Systematic searches were carried out in seven major databases, using both subject headings and key words. Papers were screened, data extracted, quality appraised, and analysed by two reviewers independently, using predefined criteria. Study quality was assessed using the Cochrane Collaboration risk of bias tool. Perceived stress was the primary outcome. Secondary outcomes include mental health, physical health, quality of life, and health service utilisation. Statistical meta-analysis was not possible. Disagreements were adjudicated by a third party reviewer.<p></p> <b>Results</b> Three studies (n = 183 participants) were included in the final analysis. The studies were undertaken in Wales (n = 16, randomised controlled trial - (RCT)), Switzerland (n = 150, RCT), and the United States (n = 17, controlled trial). 146 (80%) participants were female; mean age (SD) was 48.6 (9.4) years. Relapsing remitting MS was the main diagnostic category (n = 123, 67%); 43 (26%) had secondary progressive disease; and the remainder were unspecified. MBIs lasted 6–8 weeks; attrition rates were variable (5-43%); all employed pre- post- measures; two had longer follow up; one at 3, and one at 6 months. Socio-economic status of participants was not made explicit; health service utilisation and costs were not reported. No study reported on perceived stress. All studies reported quality of life (QOL), mental health (anxiety and depression), physical (fatigue, standing balance, pain), and psychosocial measures. Statistically significant beneficial effects relating to QOL, mental health, and selected physical health measures were sustained at 3- and 6- month follow up.<p></p> <b>Conclusion</b> From the limited data available, MBIs may benefit some MS patients in terms of QOL, mental health, and some physical health measures. Further studies are needed to clarify how MBIs might best serve the MS population.<p></p&gt

RNA:protein ratio of the unicellular organism as a characteristic of phosphorous and nitrogen stoichiometry and of the cellular requirement of ribosomes for protein synthesis

Background Mean phosphorous:nitrogen (P:N) ratios and relationships of P:N ratios with the growth rate of organisms indicate a surprising similarity among and within microbial species, plants, and insect herbivores. To reveal the cellular mechanisms underling this similarity, the macromolecular composition of seven microorganisms and the effect of specific growth rate (SGR) on RNA:protein ratio, the number of ribosomes, and peptide elongation rate (PER) were analyzed under different conditions of exponential growth. Results It was found that P:N ratios calculated from RNA and protein contents in these particular organisms were in the same range as the mean ratios reported for diverse organisms and had similar positive relationships with growth rate, consistent with the growth-rate hypothesis. The efficiency of protein synthesis in microorganisms is estimated as the number of active ribosomes required for the incorporation of one amino acid into the synthesized protein. This parameter is calculated as the SGR:PER ratio. Experimental and theoretical evidence indicated that the requirement of ribosomes for protein synthesis is proportional to the RNA:protein ratio. The constant of proportionality had the same values for all organisms, and was derived mechanistically from the characteristics of the protein-synthesis machinery of the cell (the number of nucleotides per ribosome, the average masses of nucleotides and amino acids, the fraction of ribosomal RNA in the total RNA, and the fraction of active ribosomes). Impairment of the growth conditions decreased the RNA:protein ratio and increased the overall efficiency of protein synthesis in the microorganisms. Conclusion Our results suggest that the decrease in RNA:protein and estimated P:N ratios with decrease in the growth rate of the microorganism is a consequence of an increased overall efficiency of protein synthesis in the cell resulting from activation of the general stress response and increased transcription of cellular maintenance genes at the expense of growth related genes. The strong link between P:N stoichiometry, RNA:protein ratio, ribosomal requirement for protein synthesis, and growth rate of microorganisms indicated by the study could be used to characterize the N and P economy of complex ecosystems such as soils and the oceans

On Semiclassical Limits of String States

We explore the relation between classical and quantum states in both open and closed (super)strings discussing the relevance of coherent states as a semiclassical approximation. For the closed string sector a gauge-fixing of the residual world-sheet rigid translation symmetry of the light-cone gauge is needed for the construction to be possible. The circular target-space loop example is worked out explicitly.Comment: 12 page