Exact exchange optimized effective potential and self-compression of stabilized jellium clusters

In this work, we have used the exchange-only optimized effective potential in the self-consistent calculations of the density functional Kohn-Sham equations for simple metal clusters in stabilized jellium model with self-compression. The results for the closed-shell clusters of Al, Li, Na, K, and Cs with $N=$2, 8, 18, 20, 34, and 40 show that the clusters are 3% more compressed here than in the local spin density approximation. On the other hand, in the LSDA, neglecting the correlation results in a contraction by 1.4%.Comment: 7 pages, RevTex, 5 eps figures, 2 table

Ciradian dysrhythmias in the EEG of children with clonazepam treatment

The effects of different anticonvulsants on the system of cir-cadian and ultradian rhythms in the EEG of children was investigated in ten 24*-h recordings of children with different forms of epilepsy. Circadian dysrhythmias could be found in children with Clonazepam treatment

Disorder Induced Stripes in d-Wave Superconductors

Stripe phases are observed experimentally in several copper-based high-Tc superconductors near 1/8 hole doping. However, the specific characteristics may vary depending on the degree of dopant disorder and the presence or absence of a low- temperature tetragonal phase. On the basis of a Hartree-Fock decoupling scheme for the t-J model we discuss the diverse behavior of stripe phases. In particular the effect of inhomogeneities is investigated in two distinctly different parameter regimes which are characterized by the strength of the interaction. We observe that small concen- trations of impurities or vortices pin the unidirectional density waves, and dopant disorder is capable to stabilize a stripe phase in parameter regimes where homogeneous phases are typically favored in clean systems. The momentum-space results exhibit universal features for all coexisting density-wave solutions, nearly unchanged even in strongly disordered systems. These coexisting solutions feature generically a full energy gap and a particle-hole asymmetry in the density of states.Comment: 28 pages, 8 figure

Raman Scattered He II λ\lambda 6545 Line in the Symbiotic Star V1016 Cygni

We present a spectrum of the symbiotic star V1016 Cyg observed with the 3.6 m Canada-France-Hawaii Telescope, in order to illustrate a method to measure the covering factor of the neutral scattering region around the giant component with respect to the hot emission region around the white dwarf component. In the spectrum, we find broad wings around H$\alpha$ and a broad emission feature around 6545${\rm \AA}$ that is blended with the [N II]$\lambda$ 6548 line. These two features are proposed to be formed by Raman scattering by atomic hydrogen, where the incident radiation is proposed to be UV continuum radiation around Ly$\beta$ in the former case and He II $\lambda$ 1025 emission line arising from $n=6\to n=2$ transitions for the latter feature. We remove the H$\alpha$ wings by a template Raman scattering wing profile and subtract the [N II] $\lambda$ 6548 line using the 3 times stronger [N II] $\lambda$ 6583 feature in order to isolate the He II Raman scattered 6545 \AA line. We obtain the flux ratio $F_{6545}/F_{6560}=0.24$ of the He II $\lambda$ 6560 emission line and the 6545 \AA feature for V1016 Cyg. Under the assumption that the He II emission from this object is isotropic, this ratio is converted to the ratio $\Phi_{6545}/\Phi_{1025}=0.17$ of the number of the incident photons and that of the scattered photons. This implies that the scattering region with H I column density $N_{HI}\ge 10^{20}{\rm cm^{-2}}$ covers 17 per cent of the emission region. By combining the presumed binary period $\sim 100$ yrs of this system we infer that a significant fraction of the slow stellar wind from the Mira component is ionized and that the scattering region around the Mira extends a few tens of AU, which is closely associated with the mass loss process of the Mira component.Comment: 12 pages, 6 figures, accepted for publication in Ap

Characteristics of an Electric/Magnetic Quadrupole Detector for Low Voltage Scanning Electron Microscopy

The electric/magnetic quadrupole detector allow\u27s efficient detection of secondary electrons in low voltage scanning electron microscopy without introducing disturbing aberrations. The original detector of this type was built in 1986; it has now been equipped with scintillator-photomultiplier assemblies on both positive electrodes. Their signals, A and B, can be combined to A+B or A-B, thus enhancing or suppressing different types of contrast. The aberration disc produced by the present design of detector was estimated to have a diameter of 10 nm. Experimentally, no deterioration of image resolution was observed. The collection efficiency was predicted to be 26% and can be better than 65% with an optimized collector size. For experimental determination, the detector was first calibrated by reflecting the primary beam of known current towards the scintillators. The detected proportion of secondary electrons was subsequently determined from the detected signal. The efficiency was found to be 20% which is in agreement with the theoretical value

Discovery of kilogauss magnetic fields in three DA white dwarfs

We have detected longitudinal magnetic fields between 2 and 4 kG in three (WD 0446$-$790, WD 1105$-$048, WD 2359$-$434) out of a sample of 12 normal DA white dwarfs by using optical spectropolarimetry done with the VLT Antu 8 m telescope equipped with FORS1. With the exception of 40 Eri B (4 kG) these are the first positive detections of magnetic fields in white dwarfs below 30 kG. Although suspected, it was not clear whether a significant fraction of white dwarfs contain magnetic fields at this level. These fields may be explained as fossil relics from magnetic fields in the main-sequence progenitors considerably enhanced by magnetic flux conservation during the shrinkage of the core. A detection rate of 25 % (3/12) may indicate now for the first time that a substantial fraction of white dwarfs have a weak magnetic field. This result, if confirmed by future observations, would form a cornerstone for our understanding on the evolution of stellar magnetic fields. Keywords: stars: white dwarfs - stars: magnetic fields - stars: individual: WD0446-790, WD1105-048, WD2359-434Comment: 15 pages, 7 figures, Astronomy and Astrophysics, in pres

Charging Effects in Low-Voltage Scanning Electron Microscope Metrology

Low voltage operation of the scanning electron microscope is being increasingly used to avoid negative charging in e-beam inspection and metrology. Positive charging effects, however, may still disturb the measurement accuracy even with low primary beam energies. Current investigations have revealed that no errors due to positive charging occur on resist structures on semiconductor substrates. But samples with metal structures on insulating substrates do involve disturbing effects due to positive charging. The difference in behavior between these groups of samples is attributed to the fundamental difference between insulator and conductor charging. This difference is due to different field geometries on the respective surfaces