Thermal simulation of magnetization reversals for size-distributed assemblies of core-shell exchange biased nanoparticles

A temperature dependent coherent magnetization reversal model is proposed for size-distributed assemblies of ferromagnetic nanoparticles and ferromagnetic-antiferromagnetic core-shell nanoparticles. The nanoparticles are assumed to be of uniaxial anisotropy and all aligned along their easy axis. The thermal dependence is included by considering thermal fluctuations, implemented via the N\'eel-Arrhenius theory. Thermal and angular dependence of magnetization reversal loops, coercive field and exchange-bias field are obtained, showing that F-AF size-distributed exchange-coupled nanoparticles exhibit temperature-dependent asymmetric magnetization reversal. Also, non-monotonic evolutions of He and Hc with T are demonstrated. The angular dependence of Hc with T exhibits a complex behavior, with the presence of an apex, whose position and amplitude are strongly T dependent. The angular dependence of He with T exhibits complex behaviors, which depends on the AF anisotropy and exchange coupling. The resulting angular behavior demonstrates the key role of the size distribution and temperature in the magnetic response of nanoparticles.Comment: Revised arguments in Introduction and last sectio

Topological signature of deterministic chaos in short nonstationary signals from an optical parametric oscillator

Although deterministic chaos has been predicted to occur in the triply resonant optical parametric oscillator (TROPO) fifteen years ago, experimental evidence of chaotic behavior in this system has been lacking so far, in marked contrast with most nonlinear systems, where chaos has been actively tracked and found. This situation is probably linked to the high sensitivity of the TROPO to perturbations, which adversely affects stationary operation at high power. We report the experimental observation in this system of a burst of irregular behavior of duration 80 microseconds. Although the system is highly nonstationary over this time interval, a topological analysis allows us to extract a clearcut signature of deterministic chaos from a time series segment of only 9 base cycles (3 microseconds). This result suggests that nonstationarity is not necessarily an obstacle to the characterization of chaos

Frequency selection by soliton excitation in nondegenerate intracavity downconversion

We show that soliton excitation in intracavity downconversion naturally selects a strictly defined frequency difference between the signal and idler fields. In particular, this phenomenon implies that if the signal has smaller losses than the idler then its frequency is pulled away from the cavity resonance and the idler frequency is pulled towards the resonance and {\em vice versa}. The frequency selection is shown to be closely linked with the relative energy balance between the idler and signal fields.Comment: 5 pages, 3 figures. To appear in Phys Rev Let

Optimal Use of Vitamin D When Treating Osteoporosis

Inadequate serum 25-hydroxyvitamin D (25[OH]D) concentrations are associated with muscle weakness, decreased physical performance, and increased propensity in falls and fractures. This paper discusses several aspects with regard to vitamin D status and supplementation when treating patients with osteoporosis in relation to risks and prevention of falls and fractures. Based on evidence from literature, adequate supplementation with at least 700 IU of vitamin D, preferably cholecalciferol, is required for improving physical function and prevention of falls and fractures. Additional calcium supplementation may be considered when dietary calcium intake is below 700 mg/day. For optimal bone mineral density response in patients treated with antiresorptive or anabolic therapy, adequate vitamin D and calcium supplementation is also necessary. Monitoring of 25(OH)D levels during follow-up and adjustment of vitamin D supplementation should be considered to reach and maintain adequate serum 25(OH)D levels of at least 50 nmol/L, preferably greater than 75 nmol/L in all patients

Efficacy and safety of piroxicam revisited. A global meta-analysis of randomised clinical trials.

BACKGROUND: The relative efficacy/safety profiles of traditional (non-selective) NSAIDs (t-NSAIDs) have been repeatedly challenged. To better understand the efficacy and safety profile of piroxicam, a widely used NSAID, a meta-analysis of comparative RCTs was carried out according to the QUOROM guidance. METHODS: A systematic comprehensive research (years 1980-2006) of any comparative randomised controlled trial (of over 7-day duration) with piroxicam for the treatment of osteoarticular conditions was conducted. Conservative analyses were stratified by comparator, outcome, indication, duration, and doses. Publication bias and robustness were exhaustively investigated. RESULTS: Seventy-five comparative trials were ultimately included for analyses. Regarding global efficacy, piroxicam was more effective than naproxen [OR=1.37 (1.05; 1.77)] and nabumetone [OR=1.72 (1.26; 2.34)], while equivalent to other NSAIDS [OR=1.06 (0.96; 1.18)]. For pain and articular swelling, piroxicam was statistically equivalent to all other NSAIDs. For mobility, piroxicam appeared to be more effective than indomethacin, while equivalent to all other NSAIDs. Piroxicam was globally safer than other NSAIDs OR=0.84 [0.73; 0.96], notably indomethacin [OR=0.53 (0.43; 0.64], naproxen [OR=0.75 (0.65; 0.85)] and salicylates [OR=0.36 (0.17; 0.75)]. From a global GI safety point of view, piroxicam was better tolerated than indomethacin [OR=0.46 (0.36; 0.58)], naproxen [OR=0.66 (0.53; 0.83)] and salicylates [OR=0.45 (0.27; 0.78)] while less tolerated when compared to meloxicam [OR=1.49 (1.05; 2.13)]. Major GI effects were comparable among piroxicam users as in comparator drugs users [OR=1.33 (0.96; 1.84)], except for meloxicam [OR=2.37 (1.13; 4.97)]. The skin safety of piroxicam was statistically comparable to those of comparators [OR=1.01 (0.68; 1.51)]. CONCLUSION: This meta-analysis of RCTs support a similar to more favourable efficacy/safety profile of piroxicam as compared to other t-NSAIDs