Description: In this article, the authors analyze RR heartbeat sequences with a dynamic model that satisfactorily reproduces both the long- and the short-time statistical properties of heart beating. These properties are expressed quantitatively by means of two significant parameters, the scaling δ concerning the asymptotic effects of long-range correlation, and the quantity 1 - π establishing the amount of uncorrelated fluctuations. The authors find a correlation between the position in the phase space (δ,π) of patients with congestive heart failure and their mortality risk.

Description: In this article, the authors present a theoretical study of long-range surface plasmons propagating in a thin metallic film clad between two identical uniaxial anisotropic dielectric crystals. The authors show that the proper orientation of the optical axis of the crystal with respect to the metal surface enhances the propagation length in a wide range of frequencies, including the telecommunication region. To increase the role of anisotropy than the natural optical crystals. The authors propose Kronig-Penney model for plasmonic crystal where the substrate is a periodic sequence of dielectric delta peaks. In this model the dispersion relation for surface plasmon has a band structure where the band width tends to zero when the frequency approaches the resonant frequency.

Description: This article discusses low coordinate, monomeric molybdenum and tungsten(III) complexes. Treatment of (silox)3MCI (M = Mo, 1-CI; W, 2-CI; silox = tBu3SiO) with PMe3 and Na/Hg led to formation of monomeric, d3 phosphine adducts, (silox)3MPMe3 (M = Mo, 1-PMe3; W, 2-PMe3) via (silox)3CIMPMe3 (M = Mo, 1-CIPMe3; W, 2-CIPMe3). Structural studies show 1-PMe3 and 2-PMe3 to be highly distorted; calculations on full chemical models corroborate experimentally determined S = ½ ground states and their structural features. The compounds contain a bent M-P bond that is characteristic of significant σ/π-mixing. PMe3 may be thermally removed from 1-PMe3 in vacuo to produce 4A2´ (silox)3Mo (1), which was derivatized with CO, NO, and 1/4 P4 to form (silox)3Mo (1-CO), (silox)3MoNo (1-NO), and (silox)3MoP (1-P), respectively. Calculations revealed (silox)3W (2´) to have as S = ½ ground state, which may render it too reactive to be isolated. Treatment of 2-PMe3 with CO, NO, and 1/4 P4 formed (silox)3WCO (2-CO), (silox)3WNO (2-NO), and (silox)3WP (2-P), respectively. 2-CO and 2-NO are more conveniently prepared from Na/Hg reductions of 2-CI in the presence of CO and NO, respectively. Calculations reveal subtle effects of ndz2/(n+1)s mixing in differentiating the chemistry of Mo and W and in rationalizing the ...

Description: This article discusses low-level copper concentration measurements in silicon wafers using trace-element accelerator mass spectrometry. Accelerator mass spectrometry (AMS) is now widely used in over 30 laboratories throughout the world to measure ratios of the abundances of long-lived radioisotopes such as ¹⁰Be, ¹⁴C, ³⁶Cl, and ¹²⁷I to their stable isotopes at levels as low as 10(-16). Trace-element AMS (TEAMS) is an application of AMS to the measurement of very low levels of stable isotope impurities. Copper concentrations as low as 1 part per billion have been measured in silicon wafers. In this letter, the authors demonstrate the use of TEAMS to measure previously unknown copper concentration depth profiles in As-implanted Si wafers at a few parts per billion. To verify the TEAMS technique, the samples from the same wafer were measured with secondary ion mass spectrometry, which showed the same profiles, albeit plateauing out at a concentration level six times higher than the TEAMS measurement. The ability to measure at these levels is especially significant in light of the recent moves towards the use of copper interconnects in place of aluminum in integrated circuits.

Description: In this article, M-shell x-ray-production cross sections are reported for ₁¹H+ and ₂⁴He+ ions incident on thin targets of ₇₉Au, ₈₂Pb, ₈₃Bi, and ₉₂U. The energy of the ions ranged from 0.3 to 2.6 MeV in increments of 0.1 MeV. The first Born calculations overpredict the data at all energies studied. The perturbed-stationary-state calculations with energy loss, Coulomb deflection, and relativistic effects agree with the present data for both ₁¹H+ and ₂⁴He+ ions at ~0.35 MeV/u, overpredict the data at higher E₁/A₁, and underpredict the data at lower E₁/A₁. The electron-capture contribution to the target ionization is calculated to be less than 3.4% for the targets, projectiles, and energies reported in this work.