79 research outputs found
Selected Physical Characteristics of Medical Students
The purpose of this study was to measure selected anthropometrical characteris-tics, motor abilities and cardiorespiratory functions of medical students. Eighty-seven students were involved in this investigation. The students were categorized into five groups: (1) recreational, doing sport activities irregularly, (2) basketball and (3) handball players, having training at least two times per week, as well as men (4) and women (5) students entering medical school. In all groups the mean body mass index and waist-to-hip ratio were at the upper level of the normal range, while body fat percentage was similar to standards for sedentary subjects. Better motor per-formances were obtained from the basketball and handball players than from the other groups. Static strength for the sample was somewhat above the normal sedentary level. The resting blood pressure and heart rate for most subjects were in the normal. Cardiovascular risk factors were found in six students. Their systolic blood pressure was above 140 mm Hg. There were no sub-jects identified with low blood pressure. The heart rate was elevated for three students from the recreational group, and in the women. Bradycardia did not occur. The vital capacity and the ability to hold one’s breath was at the upper level of the normal range. The present results emphasis the need to improve the students` prevention oriented life style through participation in exercising
Van der Waals forces in density functional theory: perturbational long-range electron interaction corrections
Long-range exchange and correlation effects, responsible for the failure of
currently used approximate density functionals in describing van der Waals
forces, are taken into account explicitly after a separation of the
electron-electron interaction in the Hamiltonian into short- and long-range
components. We propose a "range-separated hybrid" functional based on a local
density approximation for the short-range exchange-correlation energy, combined
with a long-range exact exchange energy. Long-range correlation effects are
added by a second-order perturbational treatment. The resulting scheme is
general and is particularly well-adapted to describe van der Waals complexes,
like rare gas dimers.Comment: 8 pages, 1 figure, submitted to Phys. Rev.
Random-phase approximation and its applications in computational chemistry and materials science
The random-phase approximation (RPA) as an approach for computing the
electronic correlation energy is reviewed. After a brief account of its basic
concept and historical development, the paper is devoted to the theoretical
formulations of RPA, and its applications to realistic systems. With several
illustrating applications, we discuss the implications of RPA for computational
chemistry and materials science. The computational cost of RPA is also
addressed which is critical for its widespread use in future applications. In
addition, current correction schemes going beyond RPA and directions of further
development will be discussed.Comment: 25 pages, 11 figures, published online in J. Mater. Sci. (2012
Polymorphic Signature of the Anti-inflammatory Activity of 2,2′- {[1,2-Phenylenebis(methylene)]bis(sulfanediyl)}bis(4,6- dimethylnicotinonitrile)
Weak noncovalent interactions are the basic forces in crystal engineering. Polymorphism in flexible molecules is very common, leading to the development of the crystals of same organic compounds with different medicinal and material properties. Crystallization of 2,2′- {[1,2-phenylenebis(methylene)]bis(sulfanediyl)}bis(4,6-dimethylnicotinonitrile)
by evaporation at room temperature from ethyl acetate and hexane and from methanol and ethyl acetate gave stable polymorphs 4a and 4b, respectively, while in acetic acid, it gave metastable polymorph 4c. The polymorphic behavior of the compound has been visualized through singlecrystal X-ray and Hirshfeld analysis. These polymorphs are
tested for anti-inflammatory activity via the complete Freund’s adjuvant-induced rat paw model, and compounds have exhibited moderate activities. Studies of docking in the catalytic site of cyclooxygenase-2 were used to identify potential anti-inflammatory lead compounds. These results suggest that the supramolecular aggregate structure, which is formed in solution, influences the solid state structure and the biological activity obtained upon crystallization
van der Waals Interactions in Material Modelling
Van der Waals (vdW) interactions stem from electronic zero-point fluctuations and are often critical for the correct description of structure, stability, and response properties of molecules and materials, including biomolecules, nanomaterials, and material interfaces. Here, we give a conceptual as well as mathematical overview of the current state of modeling vdW interactions,focusing in particular on the consequences of different approximations for practical applications. We present a systematic classification of approximate first-principles models based on the adiabatic-connection fluctuation-dissipation theorem, namely the nonlocal density functionals, interatomic methods, and methods based on the random-phase approximation. The applicability of these methods to different types of materials and material properties is discussed in connection with availability of theoretical and experimental benchmarks. We conclude with a roadmap of the open problems that remain to be solved to construct a universal, efficient, and accurate vdW model for realistic material modeling
Fragment-Localized Kohn−Sham Orbitals via a Singles Configuration-Interaction Procedure and Application to Local Properties and Intermolecular Energy Decomposition Analysis
Differential blood pressure and heart rate responses to supramedullary brain stimulation in cats
The purpose of this study was to compare the cardiovascular responses to electrical stimulation of
different supramedullary brain regions. Arterial blood pressure (BP) and heart rate (HR) effects were
elicited by electrical stimulation of the lateral hypothalamus (LH), mammillary bodies (Mm),
substantia nigra (SN), globus pallidus (GP), and the subthalamic nucleus (Sub) in conscious, freely
moving cats. Pressor responses were obtained from all of these regions. The higher intensity of
stimulation the higher increase in BP and HR was obtained. However, clear-cut differences occurred in
the effects both during and after the termination of stimulations. Namely, a continuous increase in BP
and HR was obtained from the LH and SN. In contrast, the initial increase in BP and HR was followed
by a reduction compared to the peak value of the effects of stimulation in the GP and the Sub.
However, the BP and HR never reduced to the pre-stimulation level during the stimulation. Also the
changes following the cessation of stimulation at the different brain loci were dissimilar. The BP and
HR either returned gradually to the pre-stimulation level, or long-lasting oscillation occurred. The
electrical activity of the nucleus of the solitary tract (NTS) and the vagus nerve
co-varied with the
changes in BP and HR. It is concluded that the supramedullary stimulations produce differential
cardiovascular effects, and these effects are modified by the baroreflexes that are activated by the
electrically elicited rise in blood pressure
Promoting physical activity in medical education. Mini-review
The challenges in public health associated with sedentary lifestyle underline the need to prepare physicians to give appropriate medical counselling and exercise prescription. In addition, the medical students' lifestyle and physical fitness suggest changes in medical education. Physical education as a criterion subject in our medical school curriculum serves to direct students' attitude toward regular physical activity. The knowledge of exercise counselling is promoted by a credit course of human movement sciences
Changes in the amplitude and direction of goal-directed hand movements in the lack of visual information
The goal of the present investigation was to determine the precision of goal-directed hand movements in the lack of visual information. The movement amplitude and direction was examined under different experimental conditions. Subjects were ten female and ten male university students. The motor test was drawing 10 cm long straight line and 24 cm long zigzag line in four different experimental conditions. 1) The drawing with open eyes was followed immediately with drawing with closed eyes. 2) The drawing was executed from memory in the lack of visual information. 3) Drawing with restricted amplitude or direction. 4) Drawing with verbal feedback. The errors of the target distance and the lateral deviations from the target were different under the different experimental conditions. The largest errors and underestimation of the target distance occurred in drawing horizontal straight line with closed eyes. No statistically significant gender differences were found. It is concluded that the practice, adjustment of single movement parameter to the target, and the verbal feedback assist better the accuracy of unseen goal-directed hand movement than the recent visual memory
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