N-point functions in rolling tachyon background

We study n-point boundary correlation functions in Timelike Boundary Liouville theory, relevant for open string multiproduction by a decaying unstable D-brane. We give an exact result for the one-point function of the tachyon vertex operator and show that it is consistent with a previously proposed relation to a conserved charge in string theory. We also discuss when the one-point amplitude vanishes. Using a straightforward perturbative expansion, we find an explicit expression for a tachyon n-point amplitude for all n, however the result is still a toy model. The calculation uses a new asymptotic approximation for Toeplitz determinants, derived by relating the system to a Dyson gas at finite temperature.Comment: 30 pages, 2 figures. v2: minor corrections, comments and reference added. v3: revised version, added spatial momentum dependence and references, to appear in PR

On Superstring Disk Amplitudes in a Rolling Tachyon Background

We study the tree level scattering or emission of n closed superstrings from a decaying non-BPS brane in Type II superstring theory. We attempt to calculate generic n-point superstring disk amplitudes in the rolling tachyon background. We show that these can be written as infinite power series of Toeplitz determinants, related to expectation values of a periodic function in Circular Unitary Ensembles. Further analytical progress is possible in the special case of bulk-boundary disk amplitudes. These are interpreted as probability amplitudes for emission of a closed string with initial conditions perturbed by the addition of an open string vertex operator. This calculation has been performed previously in bosonic string theory, here we extend the analysis for superstrings. We obtain a result for the average energy of closed superstrings produced in the perturbed background.Comment: 15 pages, LaTeX2e; uses latexsym, amssymb, amsmath, slashed macros; (v2): references added, some typo fixes; (v3): reference adde

Magnetic effects in a holographic Fermi-like liquid

We explore the magnetic properties of the Fermi-like liquid represented by the D3-D7' system. The system exhibits interesting magnetic properties such as ferromagnetism and an anomalous Hall effect, which are due to the Chern-Simons term in the effective gravitational action. We investigate the spectrum of quasi-normal modes in the presence of a magnetic field and show that the magnetic field mitigates the instability towards a striped phase. In addition, we find a critical magnetic field above which the zero sound mode becomes massive.Comment: 18 pages, 15 figure

Examining the Long-Term Association of Personality With Cause-Specific Mortality in London: Four Decades of Mortality Surveillance in the Original Whitehall Smoking Cessation Trial

The personality domains of extraversion and neuroticism are regarded as being stable individual psychological characteristics, yet it remains unclear whether they are associated with chronic disease over an extended period of time. In a randomized controlled trial of smoking cessation nested within the original prospective Whitehall Study (1967–2012), the Eysenck Personality Questionnaire was administered to 832 male self-declared smokers who had undergone a medical examination during which their levels of extraversion and neuroticism were quantified. In the 42-year follow-up period, there were 781 deaths. In analyses in which participants from both trial arms were pooled, there was little evidence of a robust relation of either personality domain with death from all causes, coronary heart disease, stroke, respiratory disease, or cancer in any of our analyses. We therefore found no support for a role of either extraversion or neuroticism as determinants of long-term mortality risk

Striped instability of a holographic Fermi-like liquid

We consider a holographic description of a system of strongly-coupled fermions in 2+1 dimensions based on a D7-brane probe in the background of D3-branes. The black hole embedding represents a Fermi-like liquid. We study the excitations of the Fermi liquid system. Above a critical density which depends on the temperature, the system becomes unstable towards an inhomogeneous modulated phase which is similar to a charge density and spin wave state. The essence of this instability can be effectively described by a Maxwell-axion theory with a background electric field. We also consider the fate of zero sound at non-zero temperature.Comment: 16 pages, 9 figures; v2: added discussion and one figure. Typos correcte

Association of inflammation with specific symptoms of depression in a general population of older people: The English Longitudinal Study of Ageing

Elevated levels of inflammatory markers, such as C-reactive protein, are well documented in people with depression. Few studies have examined whether the association between inflammation and depression is symptom specific, and differs according to antidepressant treatment. Using data from the English Longitudinal Study of Ageing (N=5909), cross-sectional analyses revealed a significant dose-response association between C-reactive protein and the symptoms of fatigue (P<0.001), restless sleep (P=0.03), low energy (P=0.02) and feeling depressed (P=0.04), but not other symptoms. These associations were absent in users of anti-depressant medication. Our findings suggest the C-reactive protein-depression association is symptom-specific and modified by antidepressant treatment

Hidden Biodiversity in an Ecologically Important Freshwater Amphipod: Differences in Genetic Structure between Two Cryptic Species

Cryptic species, i.e. species that are morphologically hard to distinguish, have been detected repeatedly in various taxa and ecosystems. In order to evaluate the importance of this finding, we have to know in how far cryptic species differ in various aspects of their biology. The amphipod Gammarus fossarum is a key invertebrate in freshwater streams and contains several cryptic species. We examined the population genetic structure, genetic diversity and demographic history of two of them (type A and type B) using microsatellite markers and asked whether they show significant differences. We present results of population genetic analyses based on a total of 37 populations from the headwaters of two major European drainages, Rhine and Rhone. We found that, in both species, genetic diversity was geographically structured among and within drainages. For type A in the Rhine and type B in the Rhone, we detected significant patterns of isolation by distance. The increase of genetic differentiation with geographical distance, however, was much higher in type A than in type B. This result indicates substantial interspecific differences in population history and/or the extent of current gene flow between populations. In the Rhine, type B does not show evidence of isolation by distance, and population differentiation is relatively low across hundreds of kilometres. The majority of these populations also show signatures of recent bottlenecks. These patterns are consistent with a recent expansion of type B into the Rhine drainage. In summary, our results suggest considerable and previously unrecognized interspecific differences in the genetic structure of these cryptic keystone species

Inhomogeneous tachyon dynamics and the zipper

We study the process of inhomogeneous tachyon condensation in an intersecting D1- and anti-D1-brane system using an effective tachyon DBI action. By switching to the Hamiltonian formalism, we numerically solve for the dynamical evolution of the system at a small intersection angle. We find that the decay proceeds indefinitely and resembles the action of two zippers moving away from the intersection point at the speed of light, zipping the branes together and leaving inhomogeneous tachyon matter behind. We also discuss the range of validity of our analysis and discuss the relation of the D1-anti-D1 description of the system to one in terms of an intersecting D1-D1-brane pair.Comment: 23 pages, 12 figures. v2: added references; v3: more references, published versio

Obesity and common mental disorders: Examination of the association using alternative longitudinal models in the Whitehall II prospective cohort study

This thesis examined the bidirectional association between obesity and common mental disorders (CMDs) using alternative longitudinal models. Although previous evidence from different studies suggests that obesity increases the risk of CMDs and CMDs increase the risk of obesity, a more detailed longitudinal analysis is needed in order to better understand the temporal patterns. The participants were from the Whitehall II prospective cohort study with 5 data collection waves between 1985 and 2009 (n=10,265 participants in total contributing 35,880 person-observations over the follow-up), aged 35 to 55 at baseline. Body mass index (BMI) was determined on the basis of height and weight measured in medical examinations, and CMDs were assessed with the self-reported General Health Questionnaire (GHQ). In addition, several covariates (occupational status, sleep duration, bodily pain, alcohol consumption, smoking, physical activity, longstanding illnesses) were included. Associations were examined using multilevel regression. Obesity increased and the level of CMDs decreased with age. The development of both obesity and CMDs were characterized by cumulative developmental patterns, that is, the risk of future obesity (or CMDs) increased progressively with the number of times the person had been obese (or had CMDs) in previous study phases. Standard longitudinal regression models suggested that obesity was prospectively associated with future CMDs, whereas CMDs did not predict future risk of obesity. However, chronic CMDs increased the risk of obesity, so that only individuals with CMDs in several study phases over the follow-up phase had elevated risk of future obesity. Such cumulative pattern was not observed for chronic obesity in predicting future CMDs. Analysis of changes of BMI and CMDs over time indicated that a decrease in BMI was associated with a future decrease in CMDs, and an increase of CMDs was associated with future increase in BMI. An increase in BMI, however, was not associated with future change in CMDs, and a decrease in CMDs was not associated with a decrease in BMI, suggesting that the associations between changes in BMI and CMDs are dependent on the direction of change in the exposure. Except for bodily pain, the covariates had little if any effect on the associations between obesity and CMDs, and only age showed a consistent moderating effect such that the cross-sectional association and the association between CMDs and the future risk of obesity increased in magnitude with age. The results from several alternative longitudinal models suggest that the bidirectional association between obesity and CMDs is likely to represent the effects of multiple mechanisms that exert their influence over different time periods. Standard longitudinal regression models with only two measurement times are not sufficient to capture such complicated temporal patterns

The varying burden of depressive symptoms across adulthood : Results from six NHANES cohorts

Background: Depressive symptoms differ from each other in the degree of functional impairment they cause. The incidence of depression varies across the adult lifespan. We examined whether age moderates the impairment caused by depressive symptoms. Methods: The study sample (n = 21,056) was adults drawn from six multistage probability samples from the National Health and Nutrition Examination Survey series (NHANES, years 2005-2016) conducted in the United States using cross-sectional, representative cohorts. Depressive symptoms were assessed with the nine-item Patient Health Questionnaire (PHQ-9). We used regression models to predict high functional impairment, while controlling for sociodemographic variables and physical disorders. Results: Age moderated the association between depressive symptoms and functional impairment: middle-aged adults perceived moderate and severe symptoms as more impairing than did others. Older adults reported slightly higher impairment due to mild symptoms. The individual symptoms of low mood, feelings of worthlessness and guilt, and concentration difficulties were more strongly related to high impairment in mid-adulthood as compared to early and late adulthood. Limitations: Cross-sectional data allows only between-person comparisons. The PHQ-9 is brief and joins compound symptoms into single items. There was no information available concerning comorbid mental disorders. Co-occurring physical disorders were self-reported. Conclusions: Symptoms of depression may imply varying levels of impairment at different ages. The results suggest a need for age adjustments when estimating the functional impact of depression in the general population. Additionally, they show a need for more accurate assessments of depression-related impairment at older ages. Evidence-based programs may generally benefit from symptom- and age-specific findings.Peer reviewe