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Work-related behavior and experience patterns of entrepreneurs compared to teachers and physicians
(2011)
Purpose This study examined the status of health-related behavior and experience patterns of entrepreneurs in comparison with teachers and physicians to identify specific health risks and resources.
Methods Entrepreneurs (n = 632), teachers (n = 5,196), and physicians (n = 549) were surveyed in a cross-sectional design. The questionnaire Work-related Behavior and Experience Patterns (AVEM) was used for all professions and, in addition, two scales (health prevention and self-confidence) from the Checklist for Entrepreneurs in the sample of entrepreneurs.
Results The largest proportion of the entrepreneurs (45%) presented with a healthy pattern (compared with 18.4% teachers and 18.3% physicians). Thirty-eight percent of entrepreneurs showed a risk pattern of overexertion and stress, followed by teachers (28.9%) and physicians (20.6%). Unambitious or burnout patterns were seen in only 9.3/8.2% of entrepreneurs, respectively, and 25.3/27.3% of teachers, and 39.6/21.5% of physicians. While the distribution of patterns in teachers and physicians differed significantly between genders, a gender difference was not found among entrepreneurs. Entrepreneurs with the risk pattern of overexertion scored significantly (P < 0.01) lower in self-confidence and health care than those with the healthy pattern.
Conclusions The development of a successful enterprise depends, in part, on the health of the entrepreneur. The large proportion of entrepreneurs with the healthy pattern irrespective of gender may support the notion that self-selection effects of healthy individuals in this special career might be important. At the same time, a large proportion was at risk for overexertion and might benefit from measures to cope with professional demands and stress and promote a healthy behavior pattern.
Working memory maintenance of grasp-target information in the human posterior parietal cortex
(2011)
Event-related functional magnetic resonance imaging was applied to identify cortical areas involved in maintaining target information in working memory used for an upcoming grasping action. Participants had to grasp with their thumb and index finger of the dominant right hand three-dimensional objects of different size and orientation. Reaching-to-grasp movements were performed without visual feedback either immediately after object presentation or after a variable delay of 2-12 s. The right inferior parietal cortex demonstrated sustained neural activity throughout the delay, which overlapped with activity observed during encoding of the grasp target. Immediate and delayed grasping activated similar motor-related brain areas and showed no differential activity. The results suggest that the right inferior parietal cortex plays an important functional role in working memory maintenance of grasp-related information. Moreover, our findings confirm the assumption that brain areas engaged in maintaining information are also involved in encoding the same information, and thus extend previous findings on working memory function of the posterior parietal cortex in saccadic behavior to reach-to-grasp movements.
We investigate the connections between the magnetic fields and the X-ray emission from massive stars. Our study shows that the X-ray properties of known strongly magnetic stars are diverse: while some comply to the predictions of the magnetically confined wind model, others do not. We conclude that strong, hard, and variable X-ray emission may be a sufficient attribute of magnetic massive stars, but it is not a necessary one. We address the general properties of X-ray emission from "normal" massive stars, especially the long standing mystery about the correlations between the parameters of X-ray emission and fundamental stellar properties. The recent development in stellar structure modeling shows that small-scale surface magnetic fields may be common. We suggest a "hybrid" scenario which could explain the X-ray emission from massive stars by a combination of magnetic mechanisms on the surface and shocks in the stellar wind. The magnetic mechanisms and the wind shocks are triggered by convective motions in sub-photospheric layers. This scenario opens the door for a natural explanation of the well established correlation between bolometric and X-ray luminosities.
X-ray observations of the double-binary OB-star system QZ Car (HD 93206) obtained with the Chandra X-ray Observatory over a period of roughly 2 years are presented. The respective orbits of systems A (O9.7 I+b2 v, P-A = 21 days) and B (O8 III+o9 v, P-B = 6 days) are reasonably well sampled by the observations, allowing the origin of the X-ray emission to be examined in detail. The X-ray spectra can be well fitted by an attenuated three-temperature thermal plasma model, characterized by cool, moderate, and hot plasma components at kT similar or equal to 0.2, 0.7, and 2 keV, respectively, and a circumstellar absorption of similar or equal to 0.2 x 10(22) cm(-2). Although the hot plasma component could be indicating the presence of wind-wind collision shocks in the system, the model fluxes calculated from spectral fits, with an average value of similar or equal to 7x10(-13) erg s(-1) cm(-2), do not show a clear correlation with the orbits of the two constituent binaries. A semi-analytical model of QZ Car reveals that a stable momentum balance may not be established in either system A or B. Yet, despite this, system B is expected to produce an observed X-ray flux well in excess of the observations. If one considers the wind of the O8 III star to be disrupted by mass transfer, the model and observations are in far better agreement, which lends support to the previous suggestion of mass transfer in the O8 III+o9 v binary. We conclude that the X-ray emission from QZ Car can be reasonably well accounted for by a combination of contributions mainly from the single stars and the mutual wind-wind collision between systems A and B.
We have used x-ray waveguides as highly confining optical elements for nanoscale imaging of unstained biological cells using the simple geometry of in-line holography. The well-known twin-image problem is effectively circumvented by a simple and fast iterative reconstruction. The algorithm which combines elements of the classical Gerchberg-Saxton scheme and the hybrid-input-output algorithm is optimized for phase-contrast samples, well-justified for imaging of cells at multi-keV photon energies. The experimental scheme allows for a quantitative phase reconstruction from a single holographic image without detailed knowledge of the complex illumination function incident on the sample, as demonstrated for freeze-dried cells of the eukaryotic amoeba Dictyostelium discoideum. The accessible resolution range is explored by simulations, indicating that resolutions on the order of 20 nm are within reach applying illumination times on the order of minutes at present synchrotron sources.
The enzyme xanthine dehydrogenase (XDH) from the purple photosynthetic bacterium Rhodobacter capsulatus catalyzes the oxidation of hypoxanthine to xanthine and xanthine to uric acid as part of purine metabolism. The native electron acceptor is NAD(+) but herein we show that uric acid in its 2-electron oxidized form is able to act as an artificial electron acceptor from XDH in an electrochemically driven catalytic system. Hypoxanthine oxidation is also observed with the novel production of uric acid in a series of two consecutive 2-electron oxidation reactions via xanthine. XDH exhibits native activity in terms of its pH optimum and inhibition by allopurinol.
The TorD family of specific chaperones is divided into four subfamilies dedicated to molybdoenzyme biogenesis and a fifth one, exemplified by YcdY of Escherichia coli, for which no defined partner has been identified so far. We propose that YcdY is the chaperone of YcdX, a zinc protein involved in the swarming motility process of E. coli, since YcdY interacts with YcdX and increases its activity in vitro.
Yeast hexokinase isoenzyme ScHxk2 : stability of a two-domain protein with discontinuous domains
(2011)
The hexokinase isoenzyme 2 of Saccharomyces cerevisiae (ScHxk2) represents an archetype of a two-domain protein with the active site located in a cleft between the two domains. Binding of the substrate glucose results in a rigid body movement of the two domains leading to a cleft closure of the active site. Both domains of this enzyme are composed of discontinuous peptide sequences. This structural feature is reflected in the stability and folding of the ScHxk2 protein. Structural transitions induced by urea treatment resulted in the population of a thermodynamically stable folding intermediate, which, however, does not correspond to a molecule with one domain folded and the other unfolded. As demonstrated by different spectroscopic techniques, both domains are structurally affected by the partial denaturation. The intermediate possesses only 40% of the native secondary structural content and a substantial increase in the Stokes radius as judged by circular dichroism and dynamic light scattering analyses. One-dimensional 1H NMR data prove that all tryptophan residues are in a non-native environment in the intermediate, indicating substantial changes in the tertiary structure. Still, the intermediate possesses quite a high stability for a transition intermediate of about ;G = ;22 kJ mol;1.
Yeast hexokinase isoenzyme ScHxk2 stability of a two-domain protein with discontinuous domains
(2011)
The hexokinase isoenzyme 2 of Saccharomyces cerevisiae (ScHxk2) represents an archetype of a two-domain protein with the active site located in a cleft between the two domains. Binding of the substrate glucose results in a rigid body movement of the two domains leading to a cleft closure of the active site. Both domains of this enzyme are composed of discontinuous peptide sequences. This structural feature is reflected in the stability and folding of the ScHxk2 protein. Structural transitions induced by urea treatment resulted in the population of a thermodynamically stable folding intermediate, which, however, does not correspond to a molecule with one domain folded and the other unfolded. As demonstrated by different spectroscopic techniques, both domains are structurally affected by the partial denaturation. The intermediate possesses only 40% of the native secondary structural content and a substantial increase in the Stokes radius as judged by circular dichroism and dynamic light scattering analyses. One-dimensional H-1 NMR data prove that all tryptophan residues are in a non-native environment in the intermediate, indicating substantial changes in the tertiary structure. Still, the intermediate possesses quite a high stability for a transition intermediate of about Delta G = -22 kJ mol(-1).
Zenralamerika
(2011)
Zentralamerika
(2011)
Der Beitrag untersucht Kleists Dramentexte vor allem im Hinblick auf den "Skandal" des Koerpers und versucht dafuer eine Erklaerung zu finden. Diese besteht zunaechst im Herausfall aus dem Paradigma des aesthetischem Koerpers als einem schoenen Koerper. Zum zweiten aber auch darin, das Kleist mit seinen literarischen Mitteln eine drastische Performation des Koerpers fuer das Buehnenstueck vornahm ohne dafuer eine theatralische Praxis zu haben. Der Einsatz des Koerpers als ein Zeichen im Buehnenspiel ist daher strategisch vom Autor Kleist zu einer Aussage performiert worden, die neben den Aussagen des sprachlichen Textes eine weitere koerpersprachliche Textur konstruiert.
Zur Ektoparasitenfauna der Fledermäuse in Sachsen Anhalt : Ectoparasites of bats in Saxony-Anhalt
(2011)
During the summer 2010 several mist nettings for the monitoring of bat species were performed in Saxony-Anhalt. Captured individuals were tested for ectoparasitic infestation. The aim was to update the fauna of ectoparasites of this state and to collect data on the distribution of individual species. Regarding this, results of previous surveys are summarised. In the present study nine out of thirteen bat species were found to be infested with a total of one flea species, one species of bat flies and eight species of mites. The infestation with fleas was below the expectations. Six spinturnicid mite species out of those occurring in Germany could be ascertained for Saxony-Anhalt. These are Spinturnix acuminatus (Koch, 1836), S. andegavinus (Kolenati, 1857), S. helvetiae Deunff, Keller & Aellen, 1986, S. mystacinus (Kolenati, 1857), S. plecotinus (Koch, 1839) and S. puncata (Sundevall, 1833). Details about the infestation with parasites (abundances) of the respective bat species are presented. Further information on the biology of spinturnicid mites are given and infestation characteristics are compared with those of other surveys. Keywords: ectoparasites, bats, Chiroptera, gamasine mite, Acari, Spinturnix, Ischnopsyllidae, Nycteribiidae, Saxony-Anhalt, Germany