1,672 research outputs found

    Trends in Antiparkinsonian Medication Use in New Zealand: 1995–2011

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    Prescribing trends for medications are influenced by development of new drugs, changes in knowledge about efficacy and side effects, and priorities set by funding agencies. Changes in the utilization of antiparkinsonian agents in the outpatient community in New Zealand were investigated by using the national prescription database for the period 1995–2011. The dispensed volumes of antiparkinsonian agents were converted into number of defined daily doses per 1000 inhabitants per day for analysis. Increases in the dispensed volumes of levodopa (77%), amantadine (350%), and catechol-o-methyl transferase inhibitors (326%) occurred during the study period. Conversely, decreases in the dispensed volumes of anticholinergics (48%), selegiline (82%), and dopamine agonists (6.2%) were observed. New Zealand has seen a substantial increase of the amount of levodopa dispensed in the past 17 years. This increase appears to be related to an increase in the number of people taking the medication. We are unable to extrapolate this change to an increase in the prevalence of PD, given levodopa is used in the treatment of a number of medical conditions. The changes in other antiparkinsonian medications largely reflect changes in availability (increases in entacapone and ropinirole) and best practice treatment (declines in anticholinergics, selegiline, and tolcapone)

    Determination of characteristic muon precession and relaxation signals in FeAs and FeAs2, possible impurity phases in pnictide superconductors

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    We report muon-spin relaxation measurements of highly homogeneous samples of FeAs and FeAs2, both previously found as impurity phases in some samples of recently synthesized pnictide superconductors. We observe well defined muon precession in the FeAs sample with two precession frequencies of 38.2(3) and 22.7(9) MHz at 7.5 K, with the majority of the amplitude corresponding to the lower frequency component. In FeAs2 we confirm previous measurements showing that no long-ranged magnetic order occurs above 2 K and measure the muon spin relaxation rate, which increases on cooling. Our results exclude the possibility that previous muon-spin relaxation measurements of pnictide superconductors have been measuring the effect of these possible impurities.Comment: 4 pages, 3 figures, corrected Figure

    Enhancement of Superfluid Stiffness, Suppression of Superconducting T_c and Field-induced Magnetism in the Pnictide Superconductor LiFeAs

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    Transverse-field muon-spin rotation measurements performed on two samples of LiFeAs demonstrate that the superfluid stiffness of the superconducting condensate in relation to its superconducting transition temperature is enhanced compared to other pnictide superconductors. Evidence is seen for a field-induced magnetic state in a sample with a significantly suppressed superconducting transition temperature. The results in this system highlight the role of direct Fe-Fe interactions in frustrating pairing mediated by antiferromagnetic fluctuations and suggest that, in common with other pnictide superconductors, the system is close to a magnetic instability.Comment: 4 pages, 5 figure

    Charge carrier localization induced by excess Fe in the Fe1+y(Te,Se) superconductor system

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    We have investigated the effect of Fe nonstoichiometry on properties of the Fe1+y(Te, Se) superconductor system by means of resistivity, Hall coefficient, magnetic susceptibility, and specific heat measurements. We find that the excess Fe at interstitial sites of the (Te, Se) layers not only suppresses superconductivity, but also results in a weakly localized electronic state. We argue that these effects originate from the magnetic coupling between the excess Fe and the adjacent Fe square planar sheets, which favors a short-range magnetic order.Comment: 15 pages, 6 figures accepted for publication in PR

    Superconductivity up to 30 K in the vicinity of quantum critical point in BaFe2_{2}(As1−x_{1-x}Px_{x})2_{2}

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    We report bulk superconductivity induced by an isovalent doping of phosphorus in BaFe2_{2}(As1−x_{1-x}Px_{x})2_{2}. The P-for-As substitution results in shrinkage of lattice, especially for the FeAs block layers. The resistivity anomaly associated with the spin-density-wave (SDW) transition in the undoped compound is gradually suppressed by the P doping. Superconductivity with the maximum TcT_c of 30 K emerges at xx=0.32, coinciding with a magnetic quantum critical point (QCP) which is evidenced by the disappearance of SDW order and the linear temperature-dependent resistivity in the normal state. The TcT_c values were found to decrease with further P doping, and no superconductivity was observed down to 2 K for x≄x\geq 0.77. The appearance of superconductivity in the vicinity of QCP hints to the superconductivity mechanism in iron-based arsenides.Comment: 9 pages, 4 figures; more data; to appear in Journal of Physics: Condensed Matte

    Contrasting Pressure Effects in Sr2VFeAsO3 and Sr2ScFePO3

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    We report the resistivity measurements under pressure of two Fe-based superconductors with a thick perovskite oxide layer, Sr2VFeAsO3 and Sr2ScFePO3. The superconducting transition temperature Tc of Sr2VFeAsO3 markedly increases with increasing pressure. Its onset value, which was Tc{onset}=36.4 K at ambient pressure, increases to Tc{onset}=46.0 K at ~4 GPa, ensuring the potential of the "21113" system as a high-Tc material. However, the superconductivity of Sr2ScFePO3 is strongly suppressed under pressure. The Tc{onset} of ~16 K decreases to ~5 K at ~4 GPa, and the zero-resistance state is almost lost. We discuss the factor that induces this contrasting pressure effect.Comment: 5 pages, 4 figures, to be published in J. Phys. Soc. Jpn. No.12 (2009

    Whistler mode startup in the Michigan Mirror Machine

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    Results of investigations of whistler mode ECRH plasma startup in the Michigan Mirror Machine are presented. Electron‐velocity‐distribution and plasma‐spatial‐distribution time evolution are characterized by measurements from axially and radially moveable Langmuir probes, an endloss current detector, an electron cyclotron emission radiometer, a foil‐filtered X‐ray detector, and a diamagnetic loop at the mirror midplane. Measurements of the buildup of both electron density and perpendicular pressure (nkT⟂) are compared to predictions from various numerical models. Both modeling and data suggest the creation of a highly anisotropic electron velocity distribution function with a ‘‘sloshing electron’’ axial density profile.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87352/2/204_1.pd

    Temporal variations in river water surface elevation and slope captured by AirSWOT

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    The Surface Water and Ocean Topography (SWOT) satellite mission aims to improve the frequency and accuracy of global observations of river water surface elevations (WSEs) and slopes. As part of the SWOT mission, an airborne analog, AirSWOT, provides spatially-distributed measurements of WSEs for river reaches tens to hundreds of kilometers in length. For the first time, we demonstrate the ability of AirSWOT to consistently measure temporal dynamics in river WSE and slope. We evaluate data from six AirSWOT flights conducted between June 7–22, 2015 along a ~90 km reach of the Tanana River, AK. To validate AirSWOT measurements, we compare AirSWOT WSEs and slopes against an in situ network of 12 pressure transducers (PTs). Assuming error-free in situ data, AirSWOT measurements of river WSEs have an overall root mean square difference (RMSD) of 11.8 cm when averaged over 1 km2 areas while measurements of river surface slope have an RMSD of 1.6 cm/km for reach lengths >5 km. AirSWOT is also capable of recording accurate river WSE changes between flight dates, with an RMSD of 9.8 cm. Regrettably, observed in situ slope changes that transpired between the six flights are well below AirSWOT's accuracy, limiting the evaluation of AirSWOT's ability to capture temporal changes in slope. In addition to validating the direct AirSWOT measurements, we compare discharge values calculated via Manning's equation using AirSWOT WSEs and slopes to discharge values calculated using PT WSEs and slopes. We define or calibrate the remaining discharge parameters using a combination of in situ and remotely sensed observations, and we hold these remaining parameters constant between the two types of calculations to evaluate the impact of using AirSWOT versus the PT observations of WSE and slope. Results indicate that AirSWOT-derived discharge estimates are similar to the PT-derived discharge estimates, with an RMSD of 13.8%. Additionally, 42% of the AirSWOT-based discharge estimates fall within the PT discharge estimates' uncertainty bounds. We conclude that AirSWOT can measure multitemporal variations in river WSE and spatial variations in slope with both high accuracy and spatial sampling, providing a compelling alternative to in situ measurements of regional-scale, spatiotemporal fluvial dynamics

    Efficacy of miniaturized imacor trans-esophageal echocardiografm (TEE) prove in mechanical circulatory support.

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    Application of the miniaturized ImaCor Trans-Esophageal Echocardiogram (TEE) probe in Heart Transplant/Mechanical Cardiac Support Patients In the surgical cardiac care unit (SCCU), therapeutic interventions often need to be done at the bedside, necessitating the need for a rapidly employable diagnostic tool for the cardiac intensivist. We report the clinical utility of the miniature ImaCor TEE-probe in guiding management of post heart transplant (H-Txp) and mechanical cardiac support patients (MCS) and describe the economic benefit of such a device. This is an IRB approved retrospective review of MCS/H-Txp patients who had ImaCor TEE monitoring in the SCCU of our institution in 2011. The effect on management was stratified into 3 categories; Major (tamponade/device selection/RV failure), Moderate (weaning support device guidance/ inotrope management/fluid management/hemodynamic instability) and Minor (line placement/useful data). The ImaCor TEE-Probe was utilized in a total of 34 patients, of which 21 were either supported by MCS or were post H-Txp. Of these, 13 were on ECMO, 9 were post-VAD, 3 supported by the Impella device and 4 were post-H-Txp. 6 patients were placed on more than 1 method of MCS and 1 patient was supported by ECMO after a H-Txp. The device had a Major effect on management in 4 patients (19%), Moderate effect in 13 (62%) and a Minor effect in 4 (19%). The cost difference between this new device and the traditional TEE is also significant (900 USD vs 4000 USD). Our institution saved in excess of 150,000 USD with the use of this device instead of traditional TEE. This figure did not include the ability of this probe to be used repeatedly within a 72-hour time frame, and the potential cost of going to the operating theatre for further management. This device has proven to be an invaluable new adjunct in the SCCU by allowing previously unobtainable continuous real time monitoring of the MCS/H-Txp patient. Use of the ImaCor TEE-probe provides the cardiac intensivist with timely important clinical data that improves patient care and is economically advantageous
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