High-pressure phase transition and properties of spinel ZnMn2O4

X-ray photoelectron spectroscopy, magnetic measurements, and a single-crystal x-ray structure determination at normal pressure have shown that Jahn-Teller active manganese ions in ZnMn2O4 are present in one valence state (III) on the octahedral sites of the spinel structure. The high-pressure behavior of ZnMn2O4 was investigated up to 52 GPa using the energy-dispersive x-ray diffraction technique and synchrotron radiation. The structural first-order phase transition from the body-centered to primitive-tetragonal cell takes place at Pc=23GPa. The high-pressure phase is metastable down to normal pressure. The c/a ratio reduces from 1.62 to 1.10 above Pc and remains nearly pressure independent in the high-pressure phase. The transition is attributed to the changes in electron configuration of the Mn3+ ions. According to the crystal field theory, the eg electron of octahedrally coordinated Mn3+ is either in the d2z orbital or in the dx2−y2. In the first configuration the MnO6octahedron will be elongated and this is the case at normal pressure, while the second configuration gives the flattened octahedron. In the high-pressure phase some proportion of the eg electrons of the Mn3+ ions is moved to the dx2−y2 level, which is revealed as an abrupt fall of observed magnitude of the distortion of the bulk crystal above Pc

STUDIES ON ACUTE TOXICITY OF NICOTINE AND AGING

The mechanisms in the brain for acute toxicity of nicotine were investigated in rats. Age-related changes in acute toxicity of nicotine were also studied. An acute intraperitoneal (i. p.) or intracerebroventricular (i. c. v.) injection of nicotine intensified convulsions and death dose-dependently. But those convulsive responses induced by nicotine (i. c. v.) were more rapid and shorter than those induced by nicotine (i. p.). Acute toxic effects of nicotine were dose-dependently antagonized by mecamylamine (i. p. or i. c. v.), but not by hexamethonium (i. p.). Nicotine (10 or 24.5 mg/kg, i. p.) significantly increased dopamine, 3, 4-dihydroxyphenylacetic acid and homovanillic acid in striatum. Furthermore, electrical lesion of striatum suppressed acute toxicities of nicotine. Pretreatment of SCH-23390, but not of haloperidol or sulpiride, blocked nicotine-induced convulsions and death. Pretreatment of phenobarbioal, diazepam or MK-801 also prevented acute toxicity of nicotine. Nicotine levels in the blood and cortex after an acute i. p. injection of nicotine (24.5 mg/kg) were significantly higher in old rats than in young rats. Hepatic metabolisms of nicotine decreased age-relatedly. Also, nicotine (24.5 mg/kg, i. p.)-induced lethality tended to increase in old rats. On the other hand, nicotine (24.5 mg/kg, i. p.) did not change monoamine levels in any brain regions in old rats. These results indicate that acute toxic effects of nicotine can be attributed to a central site. Acute toxicity of nicotine may be related to dopaminergic neurons, especially in the nigrostriatal system, as well as GABAergic and glutamatergic neurons. Furthermore, stimulation of D1 receptors in the central dopaminergic system may be concerned with the propagation of acute toxic effects of nicotine. Also, acute toxicity of nicotine in old rats may be involved in two significant decreases, in hepatic metabolism of nicotine and in brain sensitivity to nicotine

Three-slit experiments and quantum nonlocality

An interesting link between two very different physical aspects of quantum mechanics is revealed; these are the absence of third-order interference and Tsirelson's bound for the nonlocal correlations. Considering multiple-slit experiments - not only the traditional configuration with two slits, but also configurations with three and more slits - Sorkin detected that third-order (and higher-order) interference is not possible in quantum mechanics. The EPR experiments show that quantum mechanics involves nonlocal correlations which are demonstrated in a violation of the Bell or CHSH inequality, but are still limited by a bound discovered by Tsirelson. It now turns out that Tsirelson's bound holds in a broad class of probabilistic theories provided that they rule out third-order interference. A major characteristic of this class is the existence of a reasonable calculus of conditional probability or, phrased more physically, of a reasonable model for the quantum measurement process.Comment: 9 pages, no figur

Soliton ratchets

The mechanism underlying the soliton ratchet, both in absence and in presence of noise, is investigated. We show the existence of an asymmetric internal mode on the soliton profile which couples, trough the damping in the system, to the soliton translational mode. Effective soliton transport is achieved when the internal mode and the external force are phase locked. We use as working model a generalized double sine-Gordon equation. The phenomenon is expected to be valid for generic soliton systems.Comment: 4 pages, 4 figure

Adolescent Experiences of Violence Victimizations Among Minors Who Exchange Sex/Experience Minor Sex Trafficking

This work investigates the associations between experiences of domestic minor sex trafficking and adolescent interpersonal violence victimizations, including intimate partner violence (IPV) and community violence. Abuse and violence in childhood are commonly proposed as risk factors for domestic minor sex trafficking. However, less is known about how interpersonal violence victimizations in adolescence connect to domestic minor sex trafficking experiences. The poly-victimization framework provides a means to understand domestic minor sex trafficking as a type of violence amid a web of additional interconnected violence victimizations. Efforts to better understand the interpersonal violence experienced by survivors of domestic minor sex trafficking are valuable in contextualizing trafficking experiences for adolescents. Data from The National Longitudinal Study of Adolescent to Adult Health, a population-based sample of adolescents in the United States (n = 12,605) were used to examine experiences of domestic minor sex trafficking for minor respondents, as measured through questions about exchanging sex for money or drugs. A multivariable logistic regression model was used to estimate the associations between domestic minor sex trafficking and IPV or community violence, while controlling for demographic variables and adolescent risk behaviors. Minors who experience community violence had significantly greater odds of having exchanged sex (aOR: 1.86; 95% CI: 1.32 -2.64). However, IPV was not significantly associated with minors’ experiences of sex exchange (aOR: 1.14; 95% CI: 0.85 -1.54). Alcohol or drug use (aOR: 1.87; 95% CI: 1.32 -2.65) and having run away (aOR: 2.04; 95% CI: 1.53 -2.72) were also significantly associated with minor sex exchange. As experiences of domestic minor sex trafficking were significantly associated with community violence victimizations, prevention and intervention efforts targeting youth at high risk for or survivors of domestic minor sex trafficking should consider how community violence victimizations impact these adolescent populations, and programming/messaging should be adjusted to account for these additional violence victimizations

Modeling the actinides with disordered local moments

A first-principles disordered local moment (DLM) picture within the local-spin-density and coherent potential approximations (LSDA+CPA) of the actinides is presented. The parameter free theory gives an accurate description of bond lengths and bulk modulus. The case of $\delta$-Pu is studied in particular and the calculated density of states is compared to data from photo-electron spectroscopy. The relation between the DLM description, the dynamical mean field approach and spin-polarized magnetically ordered modeling is discussed.Comment: 6 pages, 4 figure

Measurement of the near-threshold e+e−→DDˉe^+e^- \to D \bar D cross section using initial-state radiation

We report measurements of the exclusive cross section for $e^+e^- \to D \bar D$, where $D=D^0$ or $D^+$, in the center-of-mass energy range from the $D \bar D$ threshold to $5\mathrm{GeV}/c^2$ with initial-state radiation. The analysis is based on a data sample collected with the Belle detector with an integrated luminosity of 673 $\mathrm{fb}^{-1}$.Comment: Presented at EPS07 and LP07 conferences, published in PRD(RC

Search for the Electric Dipole Moment of the tau Lepton

We have searched for a CP violation signature arising from an electric dipole moment (d_tau) of the tau lepton in the e+e- -> tau+tau- reaction. Using an optimal observable method and 29.5 fb^{-1} of data collected with the Belle detector at the KEKB collider at sqrt{s} = 10.58 GeV, we find Re(d_tau) = (1.15 +- 1.70) x 10^{-17} ecm and Im(d_tau) = (-0.83 +- 0.86) x 10^{-17} ecm and set the 95% confidence level limits -2.2 < Re(d_tau) < 4.5 (10^{-17}ecm) and -2.5 < Im(d_tau) < 0.8 (10^{-17}ecm).Comment: 15 pages, LaTeX, 21 figures, submitted to Phys. Lett.