Pressure dependence of diffusion in simple glasses and supercooled liquids

Using molecular dynamics simulation, we have calculated the pressure dependence of the diffusion constant in a binary Lennard-Jones Glass. We observe four temperature regimes. The apparent activation volume drops from high values in the hot liquid to a plateau value. Near the critical temperature of the mode coupling theory it rises steeply, but in the glassy state we find again small values, similar to the ones in the liquid. The peak of the activation volume at the critical temperature is in agreement with the prediction of mode coupling theory

Increasing chromosome 1 copy number parallels histological progression in breast carcinogenesis

Chromosome 1 copy number in the benign breast lesions hyperplasia and atypical duct hyperplasia (ADH) was investigated using fluorescence in situ hybridization on paraffin sections. Progression of chromosome 1 changes occurring in parallel with histological progression from normal through hyperplasia and ADH to ductal carcinoma in situ (DCIS) and invasive carcinoma was also assessed, both overall and within individual patients. The mean signal number for normal cells was 1.14, while that for hyperplasia was 1.56 and ADH was 1.5, while values for DCIS of 1.95 and invasive duct carcinoma of 1.79, were higher (P< 0.001). Six of the seven cases also showed a significant trend towards an increasing proportion of cells with greater than 2 signals per nucleus occurring with histological progression (P< 0.001). These results support the concept that benign proliferative breast disease is a biological precursor of in-situ and invasive ductal carcinoma, the early histological changes possibly indicating a field effect with further genetic changes required for the development of a malignant phenotype. © 2000 Cancer Research Campaig

Prevalence and severity of mental disorders in military personnel: a standardised comparison with civilians

Aims. Provision and need for mental health services among military personnel are a major concern across nations. Two recent comparisons suggest higher rates of mental disorders in US and UK military personnel compared with civilians. However, these findings may not apply to other nations. Previous studies have focused on the overall effects of military service rather than the separate effects of military service and deployment. This study compared German military personnel with and without a history of deployment to sociodemographically matched civilians regarding prevalence and severity of 12-month DSM-IV mental disorders. Method. 1439 deployed soldiers (DS), 779 never deployed soldiers (NS) and 1023 civilians were assessed with an adapted version of the Munich Composite International Diagnostic interview across the same timeframe. Data were weighted using propensity score methodology to assure comparability of the three samples. Results. Compared with adjusted civilians, the prevalence of any 12-month disorder was lower in NS (OR: 0.7, 95% CI: 0.5–0.99) and did not differ in DS. Significant differences between military personnel and civilians regarding prevalence and severity of individual diagnoses were only apparent for alcohol (DS: OR: 0.3, 95% CI: 0.1–0.6; NS: OR: 0.2, 95% CI: 0.1–0.6) and nicotine dependence (DS: OR: 0.5, 95% CI: 0.3–0.6; NS: OR: 0.5, 95% CI: 0.3–0.7) with lower values in both military samples. Elevated rates of panic/agoraphobia (OR: 2.7, 95% CI: 1.4–5.3) and posttraumatic stress disorder (OR: 3.2, 95% CI: 1.3–8.0) were observed in DS with high combat exposure compared with civilians. Conclusions. Rates and severity of mental disorders in the German military are comparable with civilians for internalising and lower for substance use disorders. A higher risk of some disorders is reduced to DS with high combat exposure. This finding has implications for mental health service provision and the need for targeted interventions. Differences to previous US and UK studies that suggest an overall higher prevalence in military personnel might result from divergent study methods, deployment characteristics, military structures and occupational factors. Some of these factors might yield valuable targets to improve military mental health

Coherent instabilities in a semiconductor laser with fast gain recovery

We report the observation of a coherent multimode instability in quantum cascade lasers (QCLs), which is driven by the same fundamental mechanism of Rabi oscillations as the elusive Risken-Nummedal-Graham-Haken (RNGH) instability predicted 40 years ago for ring lasers. The threshold of the observed instability is significantly lower than in the original RNGH instability, which we attribute to saturable-absorption nonlinearity in the laser. Coherent effects, which cannot be reproduced by standard laser rate equations, can play therefore a key role in the multimode dynamics of QCLs, and in lasers with fast gain recovery in general.Comment: 5 pages, 4 figure

The role of mental disorders in the risk and speed of transition to alcohol use disorders among community youth

Background Among adolescents and young adults with DSM-IV alcohol use disorders (AUDs), there are inter-individual differences in the speed of transition from initial alcohol use (AU) to AUD. AUDs are highly co-morbid with other mental disorders. The factors associated with rapid transition from first AU to AUD remain unknown and the role of mental disorders in rapid transitions is unclear. Given this background we examined (1) whether prior anxiety, mood, externalizing and non-alcohol substance use disorders are related to the risk and speed of transition from first AU to DSM-IV alcohol abuse (AA) and alcohol dependence (AD) and (2) whether early age of onset of prior mental disorders (PMDs) is a promoter of rapid transition. Method A total of 3021 community subjects (97.7% lifetime AU) aged 14-24 years at baseline were followed up prospectively for up to 10 years. AU and mental disorders were assessed with the DSM-IV/M-CIDI. Results Among subjects with lifetime AU, several PMDs, such as specific phobia, bipolar disorder and nicotine dependence, were associated with an increased risk of AUD independent of externalizing disorders. Associations of PMDs with the speed of transition to AUDs were mostly weak and inconsistent. Only social phobia and externalizing disorders were associated with faster transitions to AD even after adjustment for other PMDs. Earlier age of onset of PMD was not associated with rapid transition. Conclusions Mental disorders are associated with the risk of AUD. With the possible exception of social phobia and externalizing disorders, they do not promote rapid transition, even if they occur particularly early. Future research needs to identify factors relevant to rapid transition to AU

Fast-forwarding evolution—Accelerated adaptation in a proofreading-deficient hypermutator herpesvirus

Evolution relies on the availability of genetic diversity for fitness-based selection. However, most deoxyribonucleic acid (DNA) viruses employ DNA polymerases (Pol) capable of exonucleolytic proofreading to limit mutation rates during DNA replication. The relative genetic stability produced by high-fidelity genome replication can make studying DNA virus adaptation and evolution an intensive endeavor, especially in slowly replicating viruses. Here, we present a proofreading-impaired Pol mutant (Y547S) of Marek’s disease virus that exhibits a hypermutator phenotype while maintaining unimpaired growth in vitro and wild-type (WT)-like pathogenicity in vivo. At the same time, mutation frequencies observed in Y547S virus populations are 2–5-fold higher compared to the parental WT virus. We find that Y547S adapts faster to growth in originally non-permissive cells, evades pressure conferred by antiviral inhibitors more efficiently, and is more easily attenuated by serial passage in cultured cells compared to WT. Our results suggest that hypermutator viruses can serve as a tool to accelerate evolutionary processes and help identify key genetic changes required for adaptation to novel host cells and resistance to antiviral therapy. Similarly, the rapid attenuation achieved through adaptation of hypermutators to growth in cell culture enables identification of genetic changes underlying attenuation and virulence, knowledge that could practically exploited, e.g. in the rational design of vaccines

Danger and loss events and the incidence of anxiety and depressive disorders: a prospective-longitudinal community study of adolescents and young adults

Background There are inconclusive findings regarding whether danger and loss events differentially predict the onset of anxiety and depression. Method A community sample of adolescents and young adults (n=2304, age 14-24 years at baseline) was prospectively followed up in up to four assessments over 10 years. Incident anxiety and depressive disorders were assessed at each wave using the DSM-IV/M-CIDI. Life events (including danger, loss and respectively mixed events) were assessed at baseline using the Munich Event List (MEL). Logistic regressions were used to reveal associations between event types at baseline and incident disorders at follow-up. Results Loss events merely predicted incident ‘pure' depression [odds ratio (OR) 2.4 per standard deviation, 95% confidence interval (CI) 1.5-3.9, p<0.001] whereas danger events predicted incident ‘pure' anxiety (OR 2.3, 95% CI 1.1-4.6, p=0.023) and ‘pure' depression (OR 2.5, 95% CI 1.7-3.5, p<0.001). Mixed events predicted incident ‘pure' anxiety (OR 2.9, 95% CI 1.5-5.7, p=0.002), ‘pure' depression (OR 2.4, 95% CI 1.6-3.4, p<0.001) and their co-morbidity (OR 3.6, 95% CI 1.8-7.0, p<0.001). Conclusions Our results provide further evidence for differential effects of danger, loss and respectively mixed events on incident anxiety, depression and their co-morbidity. Since most loss events referred to death/separation from significant others, particularly interpersonal loss appears to be highly specific in predicting depressio

Multi-Particle Collision Dynamics -- a Particle-Based Mesoscale Simulation Approach to the Hydrodynamics of Complex Fluids

In this review, we describe and analyze a mesoscale simulation method for fluid flow, which was introduced by Malevanets and Kapral in 1999, and is now called multi-particle collision dynamics (MPC) or stochastic rotation dynamics (SRD). The method consists of alternating streaming and collision steps in an ensemble of point particles. The multi-particle collisions are performed by grouping particles in collision cells, and mass, momentum, and energy are locally conserved. This simulation technique captures both full hydrodynamic interactions and thermal fluctuations. The first part of the review begins with a description of several widely used MPC algorithms and then discusses important features of the original SRD algorithm and frequently used variations. Two complementary approaches for deriving the hydrodynamic equations and evaluating the transport coefficients are reviewed. It is then shown how MPC algorithms can be generalized to model non-ideal fluids, and binary mixtures with a consolute point. The importance of angular-momentum conservation for systems like phase-separated liquids with different viscosities is discussed. The second part of the review describes a number of recent applications of MPC algorithms to study colloid and polymer dynamics, the behavior of vesicles and cells in hydrodynamic flows, and the dynamics of viscoelastic fluids

The role of mental disorders in the risk and speed of transition to alcohol use disorders among community youth

Background Among adolescents and young adults with DSM-IV alcohol use disorders (AUDs), there are inter-individual differences in the speed of transition from initial alcohol use (AU) to AUD. AUDs are highly co-morbid with other mental disorders. The factors associated with rapid transition from first AU to AUD remain unknown and the role of mental disorders in rapid transitions is unclear. Given this background we examined (1) whether prior anxiety, mood, externalizing and non-alcohol substance use disorders are related to the risk and speed of transition from first AU to DSM-IV alcohol abuse (AA) and alcohol dependence (AD) and (2) whether early age of onset of prior mental disorders (PMDs) is a promoter of rapid transition. Method A total of 3021 community subjects (97.7% lifetime AU) aged 14–24 years at baseline were followed up prospectively for up to 10 years. AU and mental disorders were assessed with the DSM-IV/M-CIDI. Results Among subjects with lifetime AU, several PMDs, such as specific phobia, bipolar disorder and nicotine dependence, were associated with an increased risk of AUD independent of externalizing disorders. Associations of PMDs with the speed of transition to AUDs were mostly weak and inconsistent. Only social phobia and externalizing disorders were associated with faster transitions to AD even after adjustment for other PMDs. Earlier age of onset of PMD was not associated with rapid transition. Conclusions Mental disorders are associated with the risk of AUD. With the possible exception of social phobia and externalizing disorders, they do not promote rapid transition, even if they occur particularly early. Future research needs to identify factors relevant to rapid transition to AUD