Magnetic order in the quasi-one-dimensional spin 1/2 chain, copper pyrazine dinitrate

We present the first evidence of magnetic order in the quasi-one-dimensional spin 1/2 molecular chain compound, copper pyrazine dinitrate Cu(C4H4N2)(NO3)2}. Zero field muon-spin relaxation measurements made at dilution refrigerator temperatures show oscillations in the measured asymmetry, characteristic of a quasistatic magnetic field at the muon sites. Our measurements provide convincing evidence for long range magnetic order below a temperature T_N=107(1) mK. This leads to an estimate of the interchain coupling constant of |J'|/k_B=0.046 K and to a ratio |J'/J| = 4.4 x 10^-3.Comment: 4 pages, 3 figures. Submitted to Physical Review Letter

Empirical wind model for the middle and lower atmosphere. Part 1: Local time average

The HWM90 thermospheric wind model was revised in the lower thermosphere and extended into the mesosphere and lower atmosphere to provide a single analytic model for calculating zonal and meridional wind profiles representative of the climatological average for various geophysical conditions. Gradient winds from CIRA-86 plus rocket soundings, incoherent scatter radar, MF radar, and meteor radar provide the data base and are supplemented by previous data driven model summaries. Low-order spherical harmonics and Fourier series are used to describe the major variations throughout the atmosphere including latitude, annual, semiannual, and longitude (stationary wave 1). The model represents a smoothed compromise between the data sources. Although agreement between various data sources is generally good, some systematic differences are noted, particularly near the mesopause. Root mean square differences between data and model are on the order of 15 m/s in the mesosphere and 10 m/s in the stratosphere for zonal wind, and 10 m/s and 4 m/s, respectively, for meridional wind

Muon-fluorine entangled states in molecular magnets

The information accessible from a muon-spin relaxation experiment is often limited since we lack knowledge of the precise muon stopping site. We demonstrate here the possibility of localizing a spin polarized muon in a known stopping state in a molecular material containing fluorine. The muon-spin precession that results from the entangled nature of the muon-spin and surrounding nuclear spins is sensitive to the nature of the stopping site and we use this property to identify three classes of site. We are also able to describe the extent to which the muon distorts its surroundings.Comment: 4 pages, 3 figure

Relationship between adiposity and admixture in African-American and Hispanic-American women.

ObjectiveThe objective of this study was to investigate whether differences in admixture in African-American (AFA) and Hispanic-American (HA) adult women are associated with adiposity and adipose distribution.DesignThe proportion of European, sub-Saharan African and Amerindian admixture was estimated for AFA and HA women in the Women's Heath Initiative using 92 ancestry informative markers. Analyses assessed the relationship between admixture and adiposity indices.SubjectsThe subjects included 11 712 AFA and 5088 HA self-identified post-menopausal women.ResultsThere was a significant positive association between body mass index (BMI) and African admixture when BMI was considered as a continuous variable, and age, education, physical activity, parity, family income and smoking were included covariates (P<10(-4)). A dichotomous model (upper and lower BMI quartiles) showed that African admixture was associated with a high odds ratio (OR=3.27 (for 100% admixture compared with 0% admixture), 95% confidence interval 2.08-5.15). For HA, there was no association between BMI and admixture. In contrast, when waist-to-hip ratio (WHR) was used as a measure of adipose distribution, there was no significant association between WHR and admixture in AFA but there was a strong association in HA (P<10(-4); OR Amerindian admixture=5.93, confidence interval=3.52-9.97).ConclusionThese studies show that: (1) African admixture is associated with BMI in AFA women; (2) Amerindian admixture is associated with WHR but not BMI in HA women; and (3) it may be important to consider different measurements of adiposity and adipose distribution in different ethnic population groups

The Pharmacokinetics of The Biliary Excretion of Ciprofloxacin

The pharmacokinetics of ciprofloxacin excretion have been studied in 54 patients undergoing biliary and pancreatic operations with and without obstruction of the common bile duct. High concentrations were achieved in common duct bile within 20 minutes of intravenous injection and persisted for over 3 hours after 100 mg and for over 8 hours after 200 mg. The concentration of ciprofloxacin in the bile of functioning gall bladders was much greater than that in the common duct bile. Remarkably, it was identified in therapeutic concentrations in the bile of obstructed ducts. This and the rapid fall from initially high venous concentrations probably reflect diffusion from the circulation as a result of the exceptional tissue penetration. A unique feature of this study was the finding of clinically significant concentrations in the bile of obstructed ducts

Spin-flip and spin-conserving optical transitions of the nitrogen-vacancy centre in diamond

We map out the first excited state sublevel structure of single nitrogen-vacancy (NV) colour centres in diamond. The excited state is an orbital doublet where one branch supports an efficient cycling transition, while the other can simultaneously support fully allowed optical Raman spin-flip transitions. This is crucial for the success of many recently proposed quantum information applications of the NV defects. We further find that an external electric field can be used to completely control the optical properties of a single centre. Finally, a group theoretical model is developed that explains the observations and provides good physical understanding of the excited state structure