Orbital frustration at the origin of the magnetic behavior in LiNiO2

We report on the ESR, magnetization and magnetic susceptibility measurements performed over a large temperature range, from 1.5 to 750 K, on high-quality stoichiometric LiNiO2. We find that this compound displays two distinct temperature regions where its magnetic behavior is anomalous. With the help of a statistical model based on the Kugel'-Khomskii Hamiltonian, we show that below T_of ~ 400 K, an orbitally-frustrated state characteristic of the triangular lattice is established. This then gives a solution to the long-standing controversial problem of the magnetic behavior in LiNiO2.Comment: 5 pages, 5 figures, RevTex, accepted in PR

Planar spin exchange in LiNiO_2

We study the planar spin exchange couplings in LiNiO2 using a perturbative approach. We show that the inclusion of the trigonal crystal field splitting at the Oxygen sites leads to the appearance of antiferromagnetic exchange integrals in deviation from the Goodenough-Kanamori-Anderson rules for this 90 degree bond. That gives a microscopic foundation for the recently observed coexistence of ferromagnetic and antiferromagnetic couplings in the orbitally-frustrated state of LiNiO2. (F. Reynaud et al, Phys. Rev. Lett. 86, 3638 (2001))Comment: latex, revtex4, 6 pages, 3 figure

Rev and Rex proteins of human complex retroviruses function with the MMTV Rem-responsive element

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How much money can be saved by applying intravenous antibiotics once instead of several times a day?

Background: The preparation, administration and monitoring of intravenous (IV) applications are time consuming and require human resources. We estimated the potential time and cost savings by replacing antibiotics given 3-4 times daily with antibiotics with similar spectrum and efficacy given once daily. Methods: The savings of indirect costs were estimated based on the antibiotic consumption data of a two-year period (i.e. 2007 and 2008), a nurse's mean workload per application and the average nurse's salary in Switzerland. Results: The consumption of IV antibiotics in 2007 and 2008 at the University Hospital of Basel was 29.0 and 32.2 defined daily doses (DDD) per 100 patient days, respectively. Nurses spent an estimated 13,786h on the application of the estimated 82,715 does of IV antibiotics. A total of 56,404 applications or nursing staff time costs of 338,436 Swiss Francs (CHF; 236,669 €), equal to 16% of the overall costs spent on purchasing antibiotics in the year 2008, may have been saved by switching multiple-dose antibiotics to a hypothetical once-daily antibiotic. Including disposable materials, 21% or 456,884 CHF (319,499 €) could be saved annually (purchase costs not taken into account). Conclusion: We found a potential cost saving of 21% of the purchase costs in a 750-bed institution. Hence, indirect costs should be included in the calculation of the total cost for the application of broad-spectrum IV antibiotics. Switching from a 3-4 times daily application to a once-daily antibiotic should be considered if a once-daily antibiotic is deemed equally effective and has a similar spectru

Stronger correlation between antibiotic use and the incidence of Clostridium difficile determined by culture results instead of faecal toxin detection only

The detection of Clostridium difficile in previous studies evaluating antibiotic use as a risk factor was limited to toxin assay tests. The reported associations may have been misleading due to the low sensitivity of toxin assay tests compared to culture results. Antibiotic use and the incidence of C. difficile of 19 units (wards) over 5years were analysed. Stool samples were tested for toxin A/B and cultured. The correlation of antibiotic use with the incidence of C. difficile determined by culture results was compared to the correlation determined by toxin assay results. Additionally, single antibiotics were analysed as risk factors. Of 5,772 faecal samples tested for C. difficile, 154 single-first cases were detected by the toxin assay and 251 additional single-first cases by culture. Antibiotic use was a significantly stronger risk factor in the correlation based on the culture results (R 2 = 0.63) versus toxin assay results (R 2 = 0.40). Multivariate analysis did not improve the correlation significantly and only the group of broad-spectrum beta-lactams was identified as an independent risk factor. The correlation between antibiotic use and C. difficile incidence rates significantly improves if detection is not limited to faecal toxin assays. Therefore, antibiotic pressure was previously underestimated as a risk facto

Clinical Disease Severity of Respiratory Viral Co-Infection versus Single Viral Infection: A Systematic Review and Meta-Analysis.

BACKGROUND: Results from cohort studies evaluating the severity of respiratory viral co-infections are conflicting. We conducted a systematic review and meta-analysis to assess the clinical severity of viral co-infections as compared to single viral respiratory infections. METHODS: We searched electronic databases and other sources for studies published up to January 28, 2013. We included observational studies on inpatients with respiratory illnesses comparing the clinical severity of viral co-infections to single viral infections as detected by molecular assays. The primary outcome reflecting clinical disease severity was length of hospital stay (LOS). A random-effects model was used to conduct the meta-analyses. RESULTS: Twenty-one studies involving 4,280 patients were included. The overall quality of evidence applying the GRADE approach ranged from moderate for oxygen requirements to low for all other outcomes. No significant differences in length of hospital stay (LOS) (mean difference (MD) -0.20 days, 95% CI -0.94, 0.53, p = 0.59), or mortality (RR 2.44, 95% CI 0.86, 6.91, p = 0.09) were documented in subjects with viral co-infections compared to those with a single viral infection. There was no evidence for differences in effects across age subgroups in post hoc analyses with the exception of the higher mortality in preschool children (RR 9.82, 95% CI 3.09, 31.20, p<0.001) with viral co-infection as compared to other age groups (I2 for subgroup analysis 64%, p = 0.04). CONCLUSIONS: No differences in clinical disease severity between viral co-infections and single respiratory infections were documented. The suggested increased risk of mortality observed amongst children with viral co-infections requires further investigation

Polyol synthesis, functionalisation, and biocompatibility studies of superparamagnetic iron oxide nanoparticles as potential MRI contrast agents

Iron oxide nanoparticles (IONPs) of low polydispersity were obtained through a simple polyol synthesis in high pressure and high temperature conditions. The control of the size and morphology of the nanoparticles was studied by varying the solvent used, the amount of iron precursor and the reaction time. Compared with conventional synthesis methods such as thermal decomposition or co-precipitation, this process yields nanoparticles with a narrow particle size distribution in a simple, reproducible and cost effective manner without the need for an inert atmosphere. For example, IONPs with a diameter of ca. 8 nm could be made in a reproducible manner and with good crystallinity as evidenced by X-ray diffraction analysis and high saturation magnetization value (84.5 emu g(-1)). The surface of the IONPs could be tailored post synthesis with two different ligands which provided functionality and stability in water and phosphate buffer saline (PBS). Their potential as a magnetic resonance imaging (MRI) contrast agent was confirmed as they exhibited high r1 and r2 relaxivities of 7.95 mM(-1) s(-1) and 185.58 mM(-1) s(-1) respectively at 1.4 T. Biocompatibility and viability of IONPs in primary human mesenchymal stem cells (hMSCs) was studied and confirmed

Quantum interference of ultrastable twin optical beams

We report the first measurement of the quantum phase-difference noise of an ultrastable nondegenerate optical parametric oscillator that emits twin beams classically phase-locked at exact frequency degeneracy. The measurement illustrates the property of a lossless balanced beam-splitter to convert number-difference squeezing into phase-difference squeezing and, thus, provides indirect evidence for Heisenberg-limited interferometry using twin beams. This experiment is a generalization of the Hong-Ou-Mandel interference effect for continuous variables and constitutes a milestone towards continuous-variable entanglement of bright, ultrastable nondegenerate beams.Comment: 4 pages, 4 figs, accepted by Phys. Rev. Let

Cooling of a mirror by radiation pressure

We describe an experiment in which a mirror is cooled by the radiation pressure of light. A high-finesse optical cavity with a mirror coated on a mechanical resonator is used as an optomechanical sensor of the Brownian motion of the mirror. A feedback mechanism controls this motion via the radiation pressure of a laser beam reflected on the mirror. We have observed either a cooling or a heating of the mirror, depending on the gain of the feedback loop.Comment: 4 pages, 6 figures, RevTe