Theoretical prediction of multiferroicity in double perovskite Y2_2NiMnO6_6

We put forward double perovskites of the R$_2$NiMnO$_6$ family (with $R$ a rare-earth atom) as a new class of multiferroics on the basis of {\it ab initio} density functional calculations. We show that changing $R$ from La to Y drives the ground-state from ferromagnetic to antiferromagnetic with $\uparrow\uparrow\downarrow\downarrow$ spin patterns. This E$^*$-type ordering breaks inversion symmetry and generates a ferroelectric polarization of few $\mu C/cm^2$. By analyzing a model Hamiltonian we understand the microscopic origin of this transition and show that an external electric field can be used to tune the transition, thus allowing electrical control of the magnetization.Comment: 4 pages, 3 figure

Temperature independent diffuse scattering and elastic lattice deformations in relaxor PbMg1/3Nb2/3O3

The results of diffuse neutron scattering experiment on PbMg1/3Nb2/3O3 single crystal above the Burns temperature are reported. It is shown that the high temperature elastic diffuse component is highly anisotropic in low-symmetry Brillouin zones and this anisotropy can be described using Huang scattering formalism assuming that the scattering originates from mesoscopic lattice deformations due to elastic defects. The qualitative agreement between this model and the experimental data is achieved with simple isotropic defects. It is demonstrated that weak satellite maxima near the Bragg reflections can be interpreted as the finite resolution effect.Comment: 7 pages, 7 figure

Ground-water Quality in the Bethpage-Hicksville-Levittown Area, Long Island, New York, with Emphasis on Volatile Organic Compounds

A plume of contaminated ground water has been delineated within an 11.4-square-mile area in east-central Nassau County, where residential neighborhoods surround an area zoned for industrial use. The industrial zone contains several firms that, in the past, have discharged effluent containing volatile organic compounds into the upper glacial aquifer through onsite recharge basins. The upper glacial aquifer is in direct hydraulic connection with the underlying Magothy aquifer; the first continuous formation that impedes downward movement of ground water is the Raritan confining unit, which is more than 500 feet below sea level. The chemicals in ground water·and their distribution were identified through analysis of water samples collected from 56 monitoring wells and 11 industrial wells in the spring and fall of 1986 and 1987. Trichloroethylene and tetrachloroethylene were found near the water table at concentrations greater than 1,000 micrograms per liter and were detected more than 5,000 feet downgradient of the industrial zone. The distribution of several other volatile organic compounds indicates more than one contaminant source in the industrial area. The plume of contaminated ground water in 1987 was 12,000 feet long, 5,700 feet wide, and more than 500 feet thick. In 1987, water was pumped from 14 industrial wells, completed in the Magothy aquifer, at an average rate of 8.05 million gallons per day, mainly for cooling purposes. The water was returned chemically unaltered to recharge basins from which it could percolate to the water table. Water-table mounding beneath basins and drawdowns near the pumped wells greatly increase the vertical component of ground-water flow beneath the industrial zone, which has increased the rate of advective movement of contaminated ground water downward toward the screened zones of pumped wells, which are 370 to 560 feet deep in the Magothy aquifer. The concentration of tetrachloroethylene decreases much more rapidly than that of trichloroethylene downgradient of the industrial zone, which indicates that sorption and (or) biodegradation may be occurring. The major effect of industrial activity on inorganic constituents is to decrease the concentration of constituents near the water table in the vicinity of the recharge basins by the addition of water from the Magothy aquifer, where the concentration of inorganic constituents is lower

Dual structures in PZN-xPT ferroelectric relaxors

We performed x-ray diffraction studies on a series of (1-$x$)Pb(Zn$_{1/3}$Nb$_{2/3}$)O$_3$-$x$PbTiO$_3$ (PZN-$x$PT) single crystals with different incident photon energies, and therefore different penetration depths. Our results show that outer-layers of $\sim 10$ to 50 $\mu$m thick are present in all samples. The structure of those outer-layers is different from that of the inside of the crystals, by having much greater (rhombohedral) distortions. With increasing $x$, rhombohedral-type lattice distortions develop, both in the outer-layer and the inside.Comment: submitted to Appl. Phys. Let

Acquired long QT interval in athletes

Long QT syndrome (LQTS) is a common disorder that leads to dramatic patient outcomes, chief among which is sudden cardiac death. This review provides detailed data on the diagnosis, prevalence, classification, etiology. The variety of causes leading to LQTS creates difficulties in the differential diagnosis of this condition and, as a result, LQTS often remains outside the attention of physicians who monitor the health of athletes. Particular attention is paid to the acquired forms of LQTS, particularly, the drug-induced form. The results of studies aimed at studying the prevalence of LQTS and the effect of drugs on the QT interval are presented. The influence of non-steroidal anti-inflammatory drugs on the QT interval is discussed in detail because they are often used by athletes. The purpose of this review is to expand understanding of the etiology of LQTS and justify the need for careful ECG screening and pharmacological monitoring in athletes

High frequency polarization switching of a thin ferroelectric film

We consider both experimentally and analytically the transient oscillatory process that arises when a rapid change in voltage is applied to a $Ba_xSr_{1-x}TiO_3$ ferroelectric thin film deposited on an $Mg0$ substrate. High frequency ($\approx 10^{8} rad/s$) polarization oscillations are observed in the ferroelectric sample. These can be understood using a simple field-polarization model. In particular we obtain analytic expressions for the oscillation frequency and the decay time of the polarization fluctuation in terms of the material parameters. These estimations agree well with the experimental results

Geometric representations for minimalist grammars

We reformulate minimalist grammars as partial functions on term algebras for strings and trees. Using filler/role bindings and tensor product representations, we construct homomorphisms for these data structures into geometric vector spaces. We prove that the structure-building functions as well as simple processors for minimalist languages can be realized by piecewise linear operators in representation space. We also propose harmony, i.e. the distance of an intermediate processing step from the final well-formed state in representation space, as a measure of processing complexity. Finally, we illustrate our findings by means of two particular arithmetic and fractal representations.Comment: 43 pages, 4 figure

The effect of high-intensity interval training on hypertrophy, strength and oxidative capacity of active muscles in power sports athletes: a cross-sectional study

Objective: the purpose of the study was to evaluate how high-intensity interval training affects strength, oxidative capacity and hypertrophy of working muscles in power sports athletes. Materials and methods: the study included 35 male power sports athletes (powerlifting), the average age was 30 ± 5,4 years. Metabolic exhaled gas analysis (determination of the anaerobic threshold and heart rate, maximum oxygen consumption and pedaling power at the maximum oxygen consumption, oxygen consumption at the anaerobic threshold and maximum oxygen consumption), ultrasonographic measurements of the anatomical cross-sectional area of the quadriceps femoris, the assessment of the maximum strength of the quadriceps femoris and methods of mathematical statistics were utilized. Athletes were subject to bicycle ergometry testing 3 times a week during 120 days according to the following protocol: 7 intervals with pedaling power of 100% of the maximum oxygen consumption for 2 min, and intervals with a heart rate of 85% of the anaerobic threshold for 2 min. Results: after 120 days of training, power athletes significantly increased the anaerobic threshold, power and oxygen consumption by 22,7 and 14,5%, respectively, as well as power and oxygen consumption at the level of maximum oxygen consumption by 18,5 and 13,6%, respectively. Regular high-intensity training on a bicycle ergometer causes muscle-specific hypertrophy, which leads to regional changes in the quadriceps femoris muscle and an increase in its strength by 6,5%. Conclusions: the aerobic workout training protocol that we developed allows athletes to effectively and safely increase the oxidizing capacities of active muscles, while not losing their main strength indicators