Exact density oscillations in the Tonks-Girardeau gas and their optical detection.

We construct the exact time dependent density profile for a superposition of the ground and singly excited states of a harmonically trapped one dimensional Bose gas in the limit of strongly interacting particles, the Tonks-Girardeau gas. We obtain analytic results that allows one to determine the number of particles in the gas, as well as the quantum amplitudes in the superposition, from measurement results in an off-resonant light scattering experiment.

Magnetic-order-induced crystal symmetry lowering in ACr2O4 ferrimagnetic spinels.

We demonstrate that the onset of complex spin orders in ACr2O4 spinels with magnetic and Jahn-Teller active A=Fe and Cu ions lowers the lattice symmetry. This is clearly indicated by the emergence of anisotropic lattice dynamics-i.e., by the pronounced phonon splittings-even when experiments probing static distortions fail. The crystal symmetry in the magnetic phase is reduced from tetragonal to orthorhombic for both compounds. The conical spin ordering in FeCr2O4 is also manifested in the hardening of the phonon frequencies. In contrast, the multiferroic CoCr2O4 with no orbital degrees of freedom shows tiny deviations from cubic structure even in its ground state.

Multicritical end point of the first-order ferromagnetic transition in colossal magnetoresistive manganites.

We have studied the bandwidth-temperature-magnetic-field phase diagram of RE0.55Sr0.45MnO3 colossal magnetoresistance manganites with ferromagnetic metal (FM) ground state. The bandwidth was controlled both via chemical substitution and hydrostatic pressure with a focus on the vicinity of the critical pressure p;{*} where the character of the zero-field FM transition changes from first to second order. Below p;{*} the first-order FM transition extends up to a critical magnetic field. It approaches zero on the larger bandwidth side where the surface of the first-order FM phase boundary is terminated by a multicritical end point. The change in the character of the transition and the decrease of the colossal magnetoresistance effect is attributed to the reduced charge-order and orbital-order fluctuations.

Networks of quantum nanorings: programmable spintronic devices.

An array of quantum rings with local (ring by ring) modulation of the spin orbit interaction (SOI) can lead to novel effects in spin state transformation of electrons. It is shown that already small (3 x 3, 5 x 5) networks are remarkably versatile from this point of view: Working in a given network geometry, the input current can be directed to any of the output ports, simply by changing the SOI strengths by external gate voltages. Additionally, the same network with different SOI strengths can be completely analogous to the Stern-Gerlach device, exhibiting spatial-spin entanglement.

Anomalous hall effect in the (in,mn)sb dilute magnetic semiconductor.

High magnetic field study of Hall resistivity in the ferromagnetic phase of (In,Mn)Sb allows one to separate its normal and anomalous components. We show that the anomalous Hall term is not proportional to the magnetization, and that it even changes sign as a function of magnetic field. We also show that the application of pressure modifies the scattering process, but does not influence the Hall effect. These observations suggest that the anomalous Hall effect in (In,Mn)Sb is an intrinsic property and supports the application of the Berry phase theory for (III,Mn)V semiconductors. We propose a phenomenological description of the anomalous Hall conductivity, based on a field-dependent relative shift of the heavy- and light-hole valence bands and the split-off band.

Separation of orbital contributions to the optical conductivity of BaVS(3).

The correlation-driven metal-insulator transition (MIT) of BaVS(3) was studied by polarized infrared spectroscopy. In the metallic state two types of electrons coexist at the Fermi energy: the quasi-1D metallic transport of A(1g) electrons is superimposed on the isotropic hopping conduction of localized E(g) electrons. The "bad-metal" character and the weak anisotropy are the consequences of the large effective mass m(eff) approximately 7 m(e) and scattering rate Gamma > or = 160 meV of the quasiparticles in the A(1g) band. There is a pseudogap above T(MI) = 69 K, and in the insulating phase the gap follows the BCS-like temperature dependence of the structural order parameter with Delta(ch) approximately 42 meV in the ground state. The MIT is described in terms of a weakly coupled two-band model.

Magnetic scattering of spin polarized carriers in (In, Mn)Sb dilute magnetic semiconductor.

Magnetoresistance measurements on the magnetic semiconductor (In, Mn)Sb suggest that magnetic scattering in this material is dominated by isolated Mn2+ ions located outside the ferromagnetically ordered regions when the system is below T(c). A model is proposed, based on the p-d exchange between spin-polarized charge carriers and localized Mn2+ ions, which accounts for the observed behavior both below and above the ferromagnetic phase transition. The suggested picture is further verified by high-pressure experiments, in which the degree of magnetic interaction can be varied in a controlled way.

Pressure-induced ferromagnetism in (In,Mn)Sb dilute magnetic semiconductor.

Recent advances in III(1-x)Mn(x)V ferromagnetic semiconductors (for example in Ga(1-x)Mn(x)As) have demonstrated that electrical control of their spin properties can be used for manipulation and detection of magnetic signals. The Mn(2+) ions in these alloys provide magnetic moments, and at the same time act as a source of valence-band holes that mediate the Mn(2+)-Mn(2+) interactions. This coupling results in the ferromagnetic phase. In earlier workit was shown that the ferromagnetic state can be enhanced or suppressed by varying the carrier density. Here we demonstrate that, by using hydrostatic pressure to continuously tune the wavefunction overlap, one can control the strength of ferromagnetic coupling without any change in the carrier concentration. Tuning the exchange coupling by this process increases the magnetization spectacularly, and can even induce the ferromagnetic phase in an initially paramagnetic alloy. These results may open new directions for strain-engineering of nanodevices.

Fractional conductance in hydrogen-embedded gold nanowires.

Interaction of the physically adsorbed molecular hydrogen with a breaking gold nanowire results in additional stable atomic configurations in few atom contacts and appearance of fractional peaks in the conductance histogram. This effect is explained by peculiar dynamic evolution of the hydrogen-embedded nanoconstriction due to competition between tensile and capillary forces. Dimerization within the atomic wire and hydrogen-assisted stabilization of gold dimers results in preferable atomic arrangements with conductivity close to 0.5 and 1.5 of quantum conductance unit G(0)=2e(2)/h.

Hall effect and conduction anisotropy in the organic conductor (TMTSF)2PF6

Both the Hall effect and the ab(')-plane conduction anisotropy are directly addressing the unconventional normal phase properties of the Bechgaard salt (TMTSF)2PF6. We found that the dramatic reduction of the carrier density deduced from recent optical data is not reflected in an enhanced Hall resistance. The pressure and temperature dependence of the b(')-direction resistivity reveal isotropic relaxation time and do not require explanations beyond the Fermi liquid theory. Our results allow a coherent-diffusive transition in the interchain carrier propagation, however the possible crossover to Luttinger liquid behavior is placed at an energy scale above room temperature.

Pressure induced quantum critical point and non-fermi-liquid behavior in BaVS3

The phase diagram of BaVS3 is studied under pressure using resistivity measurements. The temperature of the metal to nonmagnetic Mott insulator transition decreases under pressure, and vanishes at the quantum critical point p(cr) = 20 kbar. We find two kinds of anomalous conducting states. The high-pressure metallic phase is a non-Fermi liquid described by Deltarho approximately T(n) where n = 1.2-1.3 at 1

Comparative study of the pharmacokinetics and toxicity of high-dose epirubicin with or without dexrazoxane in patients with advanced malignancy.

PURPOSE: We evaluated the toxicity and pharmacokinetics of the combination of dexrazoxane with epirubicin at dexrazoxane/epirubicin dose ratios of 5 to 9:1 in a controlled, crossover phase I study in patients with advanced malignancy. PATIENTS AND METHODS: Thirty-eight patients with a variety of malignancies were enrolled. Assessable patients received two cycles of chemotherapy consisting of epirubicin alone and in combination with dexrazoxane. Comparisons were made between the toxicity and pharmacokinetics of epirubicin in the two treatment arms, using each patient as his or her own control. Dexrazoxane and epirubicin were delivered at dose levels of 600/120 mg/m2, 900/120 mg/m2, 900/135 mg/m2, 900/150 mg/m2, and 1,200/135 mg/m2, respectively. Twenty-six patients completed two cycles of chemotherapy and were therefore assessable. RESULTS: The maximum-tolerated doses (MTDs) of dexrazoxane/epirubicin were 1,200/135 mg/m2, with the dose-limiting toxicities being neutropenia, infection, and stomatitis. There was no difference in the nadir neutrophil or platelet counts between single-agent and combination treatment at any of the dose levels. Severe vomiting and stomatitis occurred less frequently following administration of epirubicin and dexrazoxane when compared with epirubicin alone (P = .01 and .02, respectively). Prior administration of higher doses (900 mg/m2 and 1,200 mg/m2) of dexrazoxane increased the systemic clearance of epirubicin, resulting in a decrease in the area under the curve (AUC). Elimination half-life, maximum plasma concentration (Cmax), and apparent volume of distribution of epirubicin were not significantly affected by dexrazoxane. Left ventricular ejection fraction (LVEF) decreased by greater than 10% in two patients, but neither developed clinical or radiologic evidence of cardiac failure. CONCLUSION: This study demonstrates that dexrazoxane can be safely combined with escalating doses of epirubicin at dose ratios of 5 to 9:1 without having an adverse impact on toxicity. Studies are need to determine the optimal dose ratio for cardioprotection and to explore further the pharmacokinetic interactions of the two drugs at increasing doses of epirubicin supported by hematopoietic growth factors.

Intracellular binding is an important determinant of the avid hepatic uptake of the high clearance drug omeprazole.

The contribution of intracellular storage to hepatic uptake of the high clearance drug, omeprazole, was examined in the recirculating isolated perfused rat liver preparation. Following injection of [3H]omeprazole (7.5 microCi, 5 mg) into the portal vein over 1 min, livers were perfused for 5 min (N = 3) or 30 min (N = 3) and then homogenized at 4 degrees and fractionated by differential centrifugation. Radiolabelled omeprazole and metabolites were determined by scintillation counting of fractions of eluant from HPLC. Seventy per cent of drug had been taken up by the liver at 5 min and 85% at 30 min, with unchanged drug representing 43 and 7.4%, respectively, of drug taken up. At both times, 70-75% of intracellular unchanged drug and the major metabolites were located in the cytosol, and the cytosol:perfusate concentration ratio was approximately 10:1. Mitochondrial, lysosomal and microsomal fractions contained relatively little drug. Extensive cytosolic binding of omeprazole therefore contributes substantially to the initial avid hepatic first-pass uptake of this drug.

Quinine impairs quinidine clearance in rat perfused liver.

We have examined the disposition of the cinchona alkaloids quinine and quinidine in the rat recirculating isolated perfused liver preparation. When administered as separate 1 mg doses, the hepatic clearances of quinine and quinidine were similar to the hepatic perfusate rate of 10 mL min-1. When 1 mg of each was administered simultaneously, mean hepatic clearance of quinine was unchanged (9.00 +/- 2.20 mL min-1 separate dosage, n = 7; 6.87 +/- 1.77 mL min-1 simultaneous dosage, n = 7; P > 0.05). By contrast, mean hepatic clearance of quinidine was reduced significantly by concomitant quinine (10.6 +/- 1.72 mL min-1 separate dosage, n = 7; 4.82 +/- 1.25 mL min-1 simultaneous dosage, n = 7; P < 0.05). There was no significant difference in volumes of distribution when each alkaloid was administered separately (131 +/- 46 mL quinine, 129 +/- 21 mL quinidine; P > 0.05) but concomitant quinine administration increased quinidine volume of distribution to 169 +/- 30 mL (P < 0.05). Four further experiments with simultaneous dosages of 0.5 mg of each alkaloid produced similar findings, indicating that the interactions did not derive from nonlinear drug disposition.