457 research outputs found

    The structure and phase stability of CO adsorbates on Rh(110)

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    The structure of CO adsorbates on the Rh(110) surface is studied at full coverage using first-principles techniques. The relative energies of different adsorbate geometries are determined by means of accurate structure optimizations. In agreement with experiments, we find that a p2mg(2x1) 2CO structure is the most stable. The CO molecules sit on the short-bridge site (carbon below) with the molecular axis slightly tilted off the surface normal, along the (001) direction. Configurations corresponding to different distributions of tilt angles are mapped onto an anisotropic 2D Ising model whose parameters are extracted from our ab-initio calculations. We find that an order-disorder phase-transition occurs at a temperature T_c=350 K.Comment: 4 pages, latex file, 2 figures include

    Beyond Logic and Norms: A Figurational Critique of Institutional Theory in Organisation Studies

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    This paper provides a figurational critique of one of the most dominant theoretical frames within organisation studies - institutional theory. Despite its status as the leading theoretical lens for explaining organisational change, institutional theorists continue to struggle with the so called agency-structure issue and remain divided in how to overcome it. Our primary criticisms concern the propensity to invoke or generate dualisms, the reliance on the sociological frames which sustain this, and the failure to engage in any comprehensive way with Elias’s writings on this subject

    Leydig Cell Hyperplasia Mimicking a Testicular Tumour in a Patient with Klinefelter Syndrome

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    Background: Klinefelter syndrome (KS) is the most common sex-chromosomal disorder in males. Frequently under-recognized, it occurs in 1 in 500–600 male births. It is caused by the inheritance of at least one additional X chromosome from either parent. Patients often have uncommon or atypical malignancies. Patient: We describe the case of a 35-year-old man with 47XXY KS and previous cryptorchidism, presenting with a painful testicular mass. Histology confirmed Leydig cell hyperplasia. Discussion: Cryptorchidism is an established risk factor for testicular tumours and occurs six times more commonly in KS than in the general population. Despite this, large epidemiological studies have shown a reduced burden of testicular cancer in these patients. The presentation of a hypoechoic lesion on ultrasound will prompt consideration of testicular tumours, however orchalgia represents an atypical presentation. In patients with KS, Leydig cell hyperplasia is a much more common entity and should be considered early in the differential diagnosis

    Prehension movements in a patient (AC) with posterior parietal cortex damage and posterior callosal section

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    Prehension movements of the right hand were recorded in a right-handed man (AC), with an injury to the left posterior parietal cortex (PPC) and with a section of the left half of the splenium. The kinematic analysis of AC’s grasping movements in direct and perturbed con- ditions was compared to that of Wve control subjects. A novel eVect in prehension was revealed—a hemispace eVect—in healthy controls only. Movements to the left hemispace were faster, longer, and with a smaller grasp aperture; perturbation of both object position and distance resulted in the attenuation of the direction eVect on movement time and the time to velocity peak, with a reverse pattern in the time to maximum grip aperture. Nevertheless, the correlation between transport velocity amplitude and grasp aperture remained stable in both perturbed and non-perturbed movements, reXecting the coordination between reaching and grasping in control subjects. In contrast, transport and grasp, as well as their coordination in both direct and perturbed conditions, were negatively aVected by the PPC and sple- nium lesion in AC, suggesting that transport and grasp rely on two functionally identiWable subsystems

    Principal component analysis of IUE galaxy spectra

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    We analyse the UV spectral energy distribution of a sample of normal galaxies listed in the IUE-INES Guide No. 2-Normal Galaxies (Formiggini & Brosch, 2000) using a Principal Component Analysis. The sample consists of the IUE-SW spectra of the central regions of 118 galaxies, where the IUE aperture included more than 1 per cent of the galaxy size. The principal components are associated with the main components observed in the UV spectra of galaxies. The first component, accounting for the largest source of diversity, can be associated with the UV continuum emission. The second component represents the UV contribution of an underlying evolved stellar population. The third component is sensitive to the amount of activity in the central regions of galaxies and measures the strength of star formation events. In all the samples analysed here the principal component representative of star-forming activity accounts for a significant percentage of the variance. The fractional contribution to the SED by the evolved stars and by the young population are similar. Projecting the SEDs onto their eigenspectra, we find that none of the coefficients of the principal components can outline an internal correlation or can correlate with the optical morphological types. In a sub-sample of 43 galaxies, consisting of almost only compact and BCD galaxies, the third principal component defines a sequence related to the degree of starburst activity of the galaxy.Comment: 13 pages, incl. 14 figures. Accepted by MNRA

    Host Galaxies of Gamma-ray Bursts: Spectral Energy Distributions and Internal Extinction

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    We present BVRcIc broad-band flux spectra for the host galaxies of GRB970508, GRB980613, GRB980703, GRB990123 and GRB991208 obtained with the 6-m telescope of SAO RAS. The BVRcIc of these hosts are best fitted by the spectral properties of template SEDs of starburst galaxies and that there is a significant internal extinction in these host galaxies. We derived the absolute magnitudes of the GRB host galaxies making use of SEDs for the starburst galaxies. We performed the population synthesis modeling of the continuum spectral energy distribution of the host galaxies of GRB970508 and GRB980703 using different extinction laws and assuming burst and exponential scenarios of star formation. The comparison of BVRcIc broad-band flux spectra with the local starburst galaxies templates and theoretical templates as well as direct estimates (using Balmer emission lines) of the internal extinction shows that it is likely to be of great importance to take into account effects of the internal extinction in the host galaxies. From the SED of the host galaxy of GRB991208 and from the intensity of their spectral lines it follows that this is a GRB galaxy with the highest massive star-formation rate of all known GRB galaxies. The reduced luminosity of these dusty galaxies (e.g. for the host of GRB970508 A_V\sim 2 mag, for the host of GRB980703 A_V\sim 0.6 mag and for the host of GRB991208 A_V\sim 2 mag) could explain the observational fact: none of the observed GRB host galaxies with known distances is brighter than the local galaxies with the luminosity L_*.Comment: Added acknowledgement

    False Heart Rate Feedback and the Perception of Heart Symptoms in Patients with Congenital Heart Disease and Anxiety

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    Background Little is known about the mechanisms explaining an increased perception of heart symptoms in congenital heart disease (ConHD). In the present study, it was suggested that a combination of high trait anxiety and disease history increases the perception of heart symptoms. Purpose It was tested whether false heart cues will result in an increased perception of heart symptoms in patients with ConHD and anxiety. Method Thirty-six patients with ConHD and 44 healthy controls performed two exercise tasks. During one of the exercise tasks, participants were exposed to a false heart cue consisting of false heart rate feedback (regular or irregular). Perceived heart symptoms were assessed and heart rate, arterial partial pressure of CO2, and respirator rate were monitored continuously. Results In line with the predictions, false heart rate feedback resulted in an increased perception of heart symptoms in high trait anxious patients with ConHD that could not be explained by acute heart dysfunction. However, unexpectedly, this effect was not observed immediately after the false heart rate feedback task but after a second exercise task without false feedback. Conclusion The results suggest that not the sole presence of ConHD but ConHD in combination with high trait anxiety results in a vulnerability to overperceive heart symptom
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