457 research outputs found
The structure and phase stability of CO adsorbates on Rh(110)
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
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
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
Effect of packed red blood cell transfusion on cerebral oxygenation and metabolism after subarachnoid hemorrhage
Prehension movements in a patient (AC) with posterior parietal cortex damage and posterior callosal section
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
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
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
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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