The Co-Ni distribution in decagonal Al69.7(4)Co10.0(4)Ni20.3(4)

The Co-Ni distribution in d-Al69.7(4)Co10.0(4)Ni20.3(4) was investigatedbased on X-ray and neutron diffraction data. The structure was modelledin higher dimensional space using the ‘charge-flipping’ and ‘low-densityelimination’ methods and it was quantitatively refined inthree-dimensional space employing a pseudo-approximant approach. Inhigher-dimensional description, the Co atoms are found at the centre ofone of the two symmetry independent occupation domains, enclosed byregions mainly occupied by Ni. The other occupation domain is mostlyoccupied by Al. In physical space Co atoms are located in the centres ofsmall Al pentagons and form pentagonal units, which are arranged indecagonal rings. On these sites Co is partly substituted by Ni, whileall other transition metal sites are occupied by Ni and to a minordegree by Al. The fraction of Co found on transition metal sitesdecreases with decreasing Co-Co distances, whereby Co is replaced by Ni

The anomaly-induced effective action and natural inflation

The anomaly-induced inflation (modified Starobinsky model) is based on the application of the effective quantum field theory approach to the Early Universe. We present a brief general review of the model and show that it does not require a fine-tuning for the parameters of the theory or initial data, gives a real chance to meet a graceful exit to the FRW phase and also has positive features with respect to the metric perturbations.Comment: Invited talk at the International Workshop on Astroparticle and High Energy Physics, October 14 - 18, 2003, Valencia, Spai

Anomalous Hall effect in NiPt thin films

We study Hall effect in sputtered NixPt1-x thin films with different Ni concentrations. Temperature, magnetic field and angular dependencies are analyzed and the phase diagram of NiPt thin films is obtained. It is found that films with sub-critical Ni concentration exhibit cluster-glass behavior at low temperatures with a perpendicular magnetic anisotropy below the freezing temperature. Films with over-critical Ni concentration are ferromagnetic with parallel anisotropy. At the critical concentration the state of the film is strongly frustrated. Such films demonstrate canted magnetization with the easy axis rotating as a function of temperature. The magnetism appears via consecutive paramagnetic - cluster glass - ferromagnetic transitions, rather than a single second-order phase transition. But most remarkably, the extraordinary Hall effect changes sign at the critical concentration. We suggest that this is associated with a reconstruction of the electronic structure of the alloy at the normal metal - ferromagnet quantum phase transition.Comment: 12 pages, 17 figure

Continuous measurement of heart rate variability following carbon dioxide pneumoperitoneum during nitrous oxide/sevoflurane anaesthesia

Background: Previous studies of autonomic nervous system activity through analysis of heart rate variability (HRV) have demonstrated increased sympathetic activity during positive-pressure pneumoperitoneum. We employed an online, continuous method for rapid HRV analysis (MemCalc™, Tarawa, Suwa Trust, Tokyo, Japan) to demonstrate rapid changes in autonomic nervous system during pneumoperitoneum for laparoscopy. Method: The powers of low-frequency (LF) (0.04-0.15 Hz) and high-frequency (HF) (0.15-0.4 Hz) components of HRV in 20 healthy adult patients were monitored under sevoflurane anaesthesia for 10 minutes after the initiation of carbon dioxide pneumoperitoneum at 10 mmHg. Results: Heart rate increased promptly, but transiently, just after peritoneal insufflation. At that time, the ratio between the LF and HF components increased on HRV. Similar, but small, changes occurred following head-up positioning. Conclusion: By monitoring HRV continuously, we have demonstrated that the change in autonomic nervous system balance induced by peritoneal insufflation was prompt and transient. The change in autonomic nervous system activity could have been due to increased sympathetic activity, reduced vagal activity, or both.Keywords: heart rate variability; positive pressure pneumoperitoneum; continuous monitorin

First Detection of Ar-K Line Emission from the Cygnus Loop

We observed the Cygnus Loop with XMM-Newton (9 pointings) and Suzaku (32 pointings) between 2002 and 2008. The total effective exposure time is 670.2 ks. By using all of the available data, we intended to improve a signal-to-noise ratio of the spectrum. Accordingly, the accumulated spectra obtained by the XIS and the EPIC show some line features around 3 keV that are attributed to the S He$\beta$ and Ar He$\alpha$ lines, respectively. Since the Cygnus Loop is an evolved ($\sim$10,000 yr) supernova remnant whose temperature is relatively low ($<$1 keV) compared with other young remnants, its spectrum is generally faint above 3.0 keV, no emission lines, such as the Ar-K line have ever been detected. The detection of the Ar-K line is the first time and we found that its abundance is significantly higher than that of the solar value; 9.0$^{+4.0}_{-3.8}$ and 8.4$^{+2.5}_{-2.7}$ (in units of solar), estimated from the XIS and the EPIC spectra, respectively. We conclude that the Ar-K line originated from the ejecta of the Cygnus Loop. Follow-up X-ray observations to tightly constrain the abundances of Ar-rich ejecta will be useful to accurately estimate the progenitor's mass.Comment: 12 pages, 9 figures, accepted for publication in PAS

Combined energy -- diffraction data refinement of decagonal AlNiCo

We incorporate realistic pair potential energies directly into a non-linear least-square fit of diffraction data to quantitatively compare structure models with experiment for the Ni-rich $d$(AlNiCo) quasicrystal. The initial structure models are derived from a few {\it a priori} assumptions (gross features of the Patterson function) and the pair potentials. In place of the common hyperspace approach to the structure refinement of quasicrystals, we use a real-space tile decoration scheme, which does not rely on strict quasiperiodicity, and makes it easy to enforce sensible local arrangements of the atoms. Inclusion of the energies provides information complementary to the diffraction data and protects the fit procedure from converging on spurious solutions. The method pinpoints sites which are likely to break the symmetry of their local environment.Comment: 7 pages, 5 figures, proceedings of the Internation Conference on Quasicrystals, Bangalore, India, August 200

Rapid spectral and flux time variations in a solar burst observed at various dm-mm wavelengths and at hard X-rays

A solar burst was observed with high sensitivity and time resolution at cm-mm wavelengths by two different radio observatories (Itapetinga and Algonquin), with high spectral time resolution at dm-mm wavelengths by patrol instruments (Sagamore Hill), and at hard X-rays (HXM Hinotori). At the onset of the major burst time structure there was a rapid rise in the spectral turnover frequency (from 5 to 15 GHz), in about 10s, coincident to a reduction of the spectral index in the optically thin part of the spectrum. The burst maxima were not time coincident at the optically thin radio frequencies and at the different hard X-ray energy ranges. The profiles at higher radio frequencies exhibited better time coincidence to the high energy X-rays. The hardest X-ray spectrum (-3) coincided with peak radio emission at the higher frequency (44 GHz). The event appeared to be built up by a first major injection of softer particles followed by other injections of harder particles. Ultrafast time structures were identified as superimposed on the burst emission at the cm-mm high sensitivity data at X-rays, with predominant repetition rates ranging from 2.0 to 3.5 Hz