Stationary relativistic jets

In this paper we describe a simple numerical approach which allows to study the structure of steady-state axisymmetric relativistic jets using one-dimensional time-dependent simulations. It is based on the fact that for narrow jets with vz≈cvz≈c the steady-state equations of relativistic magnetohydrodynamics can be accurately approximated by the one-dimensional time-dependent equations after the substitution z=ctz=ct. Since only the time-dependent codes are now publicly available this is a valuable and efficient alternative to the development of a high-specialised code for the time-independent equations. The approach is also much cheaper and more robust compared to the relaxation method. We tested this technique against numerical and analytical solutions found in literature as well as solutions we obtained using the relaxation method and found it sufficiently accurate. In the process, we discovered the reason for the failure of the self-similar analytical model of the jet reconfinement in relatively flat atmospheres and elucidated the nature of radial oscillations of steady-state jets

High-performance continuous-wave operation of superlattice terahertz quantum-cascade lasers

The cw operation of chirped-superlattice quantum-cascade lasers emitting at lambdasimilar to67 mum (4.4 THz) is analyzed. Collected (min. 33% efficiency) output powers of 4 mW per facet are measured at liquid helium temperatures and a maximum operating temperature of 48 K is reached. Under pulsed excitation at duty cycles of 0.5%-1%, slightly higher (10%) peak powers are reached, and the device can be operated up to 67 K. Low threshold current densities of 165 and 185 A cm(-2) are observed in pulsed and cw operation, respectively. The operation of the laser is examined using the Hakki-Paoli technique to estimate the net gain of the structure. (C) 2003 American Institute of Physics

ZnO@ZIF-8: Gas sensitive core-shell hetero-structures show reduced cross-sensitivity to humidity

A ‘lawn-like’ distribution of interconnected zinc oxide nanorods, coated with a metal-organic compound based on zeolitic imidazolate frameworks – ZIF-8 was prepared on microstructured thin-film interdigitated Pt-electrodes forming ZnO@ZIF-8 core-shell heterostructures and investigated as gas sensor material in relation to the identical, but uncovered pure ZnO-layer. This composite combines the gas sensing properties of the metal oxide ZnO with the specific properties of the metal-organic framework material which result in a distinct change of the conditions of gas sensing at the ZnO/ZIF-8-interface. Herein, for the first time it is reported that as prepared ZnO@ZIF-8 composite material is an attractive choice to reduce the cross-sensitivity to water vapour (humidity) in the gas sensing response towards propene and ethene. The observed change of sensitivity in relation to uncovered ZnO is discussed to be due to (i) the specific interaction of the ZIF-8 at the interface with the ZnO taking influence on the gas reaction processes, (ii) the diffusivity of ZIF-8 for the different gas components, and (iii) the sorption behaviour of the used gases at the ZnO interface and inside the ZIF-8 material

Instrumental Music Influences Recognition of Emotional Body Language

In everyday life, emotional events are perceived by multiple sensory systems. Research has shown that recognition of emotions in one modality is biased towards the emotion expressed in a simultaneously presented but task irrelevant modality. In the present study, we combine visual and auditory stimuli that convey similar affective meaning but have a low probability of co-occurrence in everyday life. Dynamic face-blurred whole body expressions of a person grasping an object while expressing happiness or sadness are presented in combination with fragments of happy or sad instrumental classical music. Participants were instructed to categorize the emotion expressed by the visual stimulus. The results show that recognition of body language is influenced by the auditory stimuli. These findings indicate that crossmodal influences as previously observed for audiovisual speech can also be obtained from the ignored auditory to the attended visual modality in audiovisual stimuli that consist of whole bodies and music

Proactive and politically skilled professionals: What is the relationship with affective occupational commitment?

The aim of this study is to extend research on employee affective commitment in three ways: (1) instead of organizational commitment the focus is on occupational commitment; (2) the role of proactive personality on affective occupational commitment is examined; and (3) occupational satisfaction is examined as a mediator and political skills as moderator in the relationship between proactive personality and affective occupational commitment. Two connected studies, one in a hospital located in the private sector and one in a university located in the public sector, are carried out in Pakistan, drawing on a total sample of over 400 employees. The results show that proactive personality is positively related to affective occupational commitment, and that occupational satisfaction partly mediates the relationship between proactive personality and affective occupational commitment. No effect is found for a moderator effect of political skills in the relationship between proactive personality and affective occupational commitment. Political skills however moderate the relationship between proactive personality and affective organizational commitment

The identification of bacteria associated with periodontal disease and dental caries by enzymatic methods

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73856/1/j.1399-302X.1986.tb00322.x.pd

Concordance of sibling's recall of measures of childhood socioeconomic position

<p>Abstract</p> <p>Background</p> <p>Studies of socioeconomic determinants of health often rely on recalled information on childhood socioeconomic position, despite limited evidence of the validity of this information. This study examined concordance between siblings of recalled measures of childhood socioeconomic position.</p> <p>Methods</p> <p>This cross-sectional study examined reports by 1280 adult sibling pairs in the National Survey of Midlife Development in the United States of seven measures of childhood socioeconomic position: father's occupation (in 9 categories), father having a professional occupation, father being a supervisor at work, father's education level, mother's education level, receipt of welfare payments, and subjective appraisal of being better or worse off financially than others.</p> <p>Results</p> <p>Concordance was high for father's professional occupation (0.97; 95% confidence interval (CI) 0.96, 0.98), father's occupation in 9 categories (0.76; 95% CI 0.73, 0.80), and receipt of welfare payments (0.95; 95% CI 0.93, 0.97). Concordance was lower for father's and mother's education level, and lowest for subjective appraisal of socioeconomic position (0.60; 95% CI 0.57, 0.64). Concordance of parental education was lower for sibling pairs with high school educations or less.</p> <p>Conclusion</p> <p>Concordance of recalled measures of childhood socioeconomic position by siblings is generally but not uniformly high.</p

Potential drug interactions and duplicate prescriptions among ambulatory cancer patients: a prevalence study using an advanced screening method

<p>Abstract</p> <p>Background</p> <p>The pharmacotherapeutic treatment of patients with cancer is generally associated with multiple side-effects. Drug interactions and duplicate prescriptions between anti-cancer drugs or interactions with medication to treat comorbidity can reinforce or intensify side-effects.</p> <p>The aim of the present study is to gain more insight into the prevalence of drug interactions and duplicate prescriptions among patients being treated in the outpatient day care departments for oncology and hematological illnesses. For the first time the prevalence of drug interactions with OTC-drugs in cancer patients will be studied. Possible risk factors for the occurrence of these drug-related problems will also be studied.</p> <p>Methods/Design</p> <p>A multicenter cross-sectional observational study of the epidemiology of drug interactions and duplicate prescriptions is performed among all oncology and hemato-oncology patients treated with systemic anti-cancer drugs at the oncology and hematology outpatient day care department of the VU University medical center and the Zaans Medical Center.</p> <p>Discussion</p> <p>In this article the prevalence of potential drug interactions in outpatient day-care patients treated with anti-cancer agents is studied using a novel more extensive screening method. If this study shows a high prevalence of drug interactions clinical pharmacists and oncologists must collaborate to develop a pharmaceutical screening programme, including an automated electronic warning system, to support drug prescribing for ambulatory cancer patient. This programme could minimize the occurrence of drug related problems such as drug interactions and duplicate prescriptions, thereby increasing quality of life.</p> <p>Trial registration</p> <p>This study is registered, number NTR2238.</p

Selective amplification of Brucella melitensis mRNA from a mixed host-pathogen total RNA

<p>Abstract</p> <p>Background</p> <p>Brucellosis is a worldwide anthropozoonotic disease caused by an in vivo intracellular pathogen belonging to genus <it>Brucella</it>. The characterization of brucelae transcriptome's during host-pathogen interaction has been limited due to the difficulty of obtaining an adequate quantity of good quality eukaryotic RNA-free pathogen RNA for downstream applications.</p> <p>Findings</p> <p>Here, we describe a combined protocol to prepare RNA from intracellular <it>B. melitensis </it>in a quantity and quality suitable for pathogen gene expression analysis. Initially, <it>B. melitensis </it>total RNA was enriched from a host:pathogen mixed RNA sample by reducing the eukaryotic RNA..Then, to increase the <it>Brucella </it>RNA concentration and simultaneously minimize the contaminated host RNA in the mixed sample, a specific primer set designed to anneal to all <it>B. melitensis </it>ORF allows the selective linear amplification of sense-strand prokaryotic transcripts in a previously enriched RNA sample.</p> <p>Conclusion</p> <p>The novelty of the method we present here allows analysis of the gene expression profile of <it>B. melitensis </it>when limited amounts of pathogen RNA are present, and is potentially applicable to both <it>in vivo </it>and <it>in vitro </it>models of infection, even at early infection time points.</p

Quantum dynamics in strong fluctuating fields

A large number of multifaceted quantum transport processes in molecular systems and physical nanosystems can be treated in terms of quantum relaxation processes which couple to one or several fluctuating environments. A thermal equilibrium environment can conveniently be modelled by a thermal bath of harmonic oscillators. An archetype situation provides a two-state dissipative quantum dynamics, commonly known under the label of a spin-boson dynamics. An interesting and nontrivial physical situation emerges, however, when the quantum dynamics evolves far away from thermal equilibrium. This occurs, for example, when a charge transferring medium possesses nonequilibrium degrees of freedom, or when a strong time-dependent control field is applied externally. Accordingly, certain parameters of underlying quantum subsystem acquire stochastic character. Herein, we review the general theoretical framework which is based on the method of projector operators, yielding the quantum master equations for systems that are exposed to strong external fields. This allows one to investigate on a common basis the influence of nonequilibrium fluctuations and periodic electrical fields on quantum transport processes. Most importantly, such strong fluctuating fields induce a whole variety of nonlinear and nonequilibrium phenomena. A characteristic feature of such dynamics is the absence of thermal (quantum) detailed balance.Comment: review article, Advances in Physics (2005), in pres