On Modeling of the Spectral Line Shape of Heavy Neutral Nonhydrogen-Like Emitters

A method of simulating the contour of the asymmetric spectral lines of neutral nonhydrogen-like atoms in a plasma is suggested. The methods of nonlinear regression are used to approximate the experimental data by a model function. The method has been checked on the spectral lines emitted by the electric arc stabilized by the walls. The method makes it possible to evaluate the Stark parameters directly from the experimentally obtained shapes of isolated or overlapping spectral lines.     

Brillouin spectra of liquid mixtures of phytol in carbontetrachloride and toluene

Measurements of Ar ion laser excited Rayleigh-Brillouin spectra of liquid phytol-carbontetrachloride and phytoltoluene mixtures were performed and used to calculate the hypersonic velocities. Therefrom it seems that the behaviour of the solutions is close to “ideal”.     

Mytilus galloprovincialis as a bioindicator of environmental conditions: the case of the eastern coast of the Adriatic Sea

The marine mussel Mytilus galloprovincialis lives attached to the surface of hard substrata, where its exposure and relative immobility allow it to record changes in ambient seawater. It is also found along the eastern coast of the Adriatic Sea. Oxygen and carbon isotopes were analysed for calcite and aragonite in separate shell layers, while major, minor and trace elements in the bulk shell were analysed to evaluate environmental conditions such as the temperature of carbonate deposition, freshwater influence and locations of anthropogenic pollution. We found that, on average, aragonite is enriched by 1.1‰ in (13)C and by 0.2‰ in (18)O compared with calcite. The calculated temperatures for M. galloprovincialis shell growth from the investigated area range from 13.4 to 20.9 °C for calcite and from 16.6 to 23.1 °C for aragonite. According to the δ(18)O and δ(13)C values of shell layers, we can separate the investigated area into three locations: those with more influence of freshwater, those with less influence of freshwater and those with marine environments. The highest concentrations of manganese, barium, boron, arsenic, nickel and chromium were observed in shells from Omis, Bacvice and Zablace (Central Adriatic) and Sv. Ivan (South Adriatic), where chemical and heavy industries are located and where sewage is known to be discharged into coastal areas. The highest concentrations of zinc, lead and copper were measured in samples from Pula, Rijeka and Gruz, where there are also ports in addition to industry.     

Search for sub-eV mass solar axions by the CERN Axion Solar Telescope with 3He buffer gas

The CERN Axion Solar Telescope (CAST) has extended its search for solar axions by using (3)He as a buffer gas. At T=1.8 K this allows for larger pressure settings and hence sensitivity to higher axion masses than our previous measurements with (4)He. With about 1 h of data taking at each of 252 different pressure settings we have scanned the axion mass range 0.39 eV?m(a)?0.64 eV. From the absence of excess x rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of g(aγ)?2.3×10(-10) GeV(-1) at 95% C.L., the exact value depending on the pressure setting. Kim-Shifman-Vainshtein-Zakharov axions are excluded at the upper end of our mass range, the first time ever for any solar axion search. In the future we will extend our search to m(a)?1.15 eV, comfortably overlapping with cosmological hot dark matter bounds.     

Bidirectional clear speech perception benefit for native and high-proficiency non-native talkers and listeners: intelligibility and accentedness

This study investigated how native language background interacts with speaking style adaptations in determining levels of speech intelligibility. The aim was to explore whether native and high proficiency non-native listeners benefit similarly from native and non-native clear speech adjustments. The sentence-in-noise perception results revealed that fluent non-native listeners gained a large clear speech benefit from native clear speech modifications. Furthermore, proficient non-native talkers in this study implemented conversational-to-clear speaking style modifications in their second language (L2) that resulted in significant intelligibility gain for both native and non-native listeners. The results of the accentedness ratings obtained for native and non-native conversational and clear speech sentences showed that while intelligibility was improved, the presence of foreign accent remained constant in both speaking styles. This suggests that objective intelligibility and subjective accentedness are two independent dimensions of non-native speech. Overall, these results provide strong evidence that greater experience in L2 processing leads to improved intelligibility in both production and perception domains. These results also demonstrated that speaking style adaptations along with less signal distortion can contribute significantly towards successful native and non-native interactions.     

Radiation hardness of gas discharge tubes and avalanche diodes used for transient voltage suppression

The widespread use of gas discharge tubes (GDTs) and avalanche diodes for transient voltage suppression (TVS) in many cases results in their exposure to ionizing radiation. The aim of this paper is to investigate the influence of irradiation on these TVS devices’ characteristics, by exposing them to a combined neutron/gamma radiation field. Experimental results show that irradiation of TVS diodes causes a lasting degradation of their protective characteristics. On the other hand, GDTs exhibit a temporary change of performance. The observed effects are presented with the accompanying theoretical interpretations, based on the interaction of radiation with materials constituting the investigated devices.     

Trapped-ion quantum simulator: experimental application to nonlinear interferometers

We show how an experimentally realized set of operations on a single trapped ion is sufficient to simulate a wide class of Hamiltonians of a spin-1/2 particle in an external potential. This system is also able to simulate other physical dynamics. As a demonstration, we simulate the action of two nth order nonlinear optical beam splitters comprising an interferometer sensitive to phase shift in one of the interferometer beam paths. The sensitivity in determining these phase shifts increases linearly with n, and the simulation demonstrates that the use of nonlinear beam splitters (n=2,3) enhances this sensitivity compared to the standard quantum limit imposed by a linear beam splitter (n=1).     

Ising quantum Hall ferromagnet in magnetically doped quantum wells

We report on the observation of the Ising quantum Hall ferromagnet with Curie temperature T(C) as high as 2 K in a modulation-doped (Cd,Mn)Te heterostructure. In this system field-induced crossing of Landau levels occurs due to the giant spin-splitting effect. Magnetoresistance data, collected over a wide range of temperatures, magnetic fields, tilt angles, and electron densities, are discussed taking into account both Coulomb electron-electron interactions and s-d coupling to Mn spin fluctuations. The critical behavior of the resistance "spikes" at T-->T(C) corroborates theoretical suggestions that the ferromagnet is destroyed by domain excitations.     

Observation and theoretical description of periodic geometric rearrangement in electronically excited nonstoichiometric sodium-fluoride clusters

We present two-color fs pump-probe spectra of Na2F which were recorded by employing excitation wavelengths around 1208 nm (pump) and ionization wavelengths around 405 nm (probe). The observed oscillatory structure of the signal with a period of 185 fs shows an excellent agreement with our simulated spectra. The employed ab initio Wigner distribution approach provides clear evidence that this observation is caused by photoinduced metal bond breaking followed by a butterfly-type periodic geometric rearrangement.     

IR finite one-loop box scalar integral with massless internal lines

The IR finite one-loop box scalar integral with massless internal lines has been recalculated. The result is very compact, simple and valid for arbitrary values of the relevant kinematic variables. It is given in terms of only two dilogarithms and a few logarithms, all of very simple arguments. Received: 31 January 2002 / Published online: 26 April 2002