916 research outputs found
Effects of Co substitution on thermodynamic and transport properties and anisotropic in Ba(FeCo)As single crystals
Single crystalline samples of Ba(FeCo)As with
have been grown and characterized via microscopic, thermodynamic and transport
measurements. With increasing Co substitution, the thermodynamic and transport
signatures of the structural (high temperature tetragonal to low temperature
orthorhombic) and magnetic (high temperature non magnetic to low temperature
antiferromagnetic) transitions are suppressed at a rate of roughly 15 K per
percent Co. In addition, for superconductivity is stabilized,
rising to a maximum of approximately 23 K for and
decreasing for higher values. The phase diagram for
Ba(FeCo)As indicates that either superconductivity can
exist in both low temperature crystallographic phases or that there is a
structural phase separation. Anisotropic, superconducting, upper critical field
data () show a significant and clear change in anisotropy between
samples that have higher temperature structural phase transitions and those
that do not. These data show that the superconductivity is sensitive to the
suppression of the higher temperature phase transition
Thermal expansion and magnetostriction of pure and doped RAgSb2 (R = Y, Sm, La) single crystals
Data on temperature-dependent, anisotropic thermal expansion in pure and
doped RAgSb2 (R = Y, Sm, La) single crystals are presented. Using the Ehrenfest
relation and heat capacity measurements, uniaxial pressure derivatives for long
range magnetic ordering and charge density wave transition temperatures are
evaluated and compared with the results of the direct measurements under
hydrostatic pressure. In-plane and c-axis pressure have opposite effect on the
phase transitions in these materials, with in-plane effects being significantly
weaker. Quantum oscillations in magnetostriction were observed for the three
pure compounds, with the possible detection of new frequencies in SmAgSb2 and
LaAgSb2. The uniaxial (along the c-axis) pressure derivatives of the dominant
extreme orbits (beta) were evaluated for YAgSb2 and LaAgSb2
Flexible provisioning of Web service workflows
Web services promise to revolutionise the way computational resources and business processes are offered and invoked in open, distributed systems, such as the Internet. These services are described using machine-readable meta-data, which enables consumer applications to automatically discover and provision suitable services for their workflows at run-time. However, current approaches have typically assumed service descriptions are accurate and deterministic, and so have neglected to account for the fact that services in these open systems are inherently unreliable and uncertain. Specifically, network failures, software bugs and competition for services may regularly lead to execution delays or even service failures. To address this problem, the process of provisioning services needs to be performed in a more flexible manner than has so far been considered, in order to proactively deal with failures and to recover workflows that have partially failed. To this end, we devise and present a heuristic strategy that varies the provisioning of services according to their predicted performance. Using simulation, we then benchmark our algorithm and show that it leads to a 700% improvement in average utility, while successfully completing up to eight times as many workflows as approaches that do not consider service failures
Flux pinning in (1111) iron-pnictide superconducting crystals
Local magnetic measurements are used to quantitatively characterize
heterogeneity and flux line pinning in PrFeAsO_1-y and NdFeAs(O,F)
superconducting single crystals. In spite of spatial fluctuations of the
critical current density on the macroscopic scale, it is shown that the major
contribution comes from collective pinning of vortex lines by microscopic
defects by the mean-free path fluctuation mechanism. The defect density
extracted from experiment corresponds to the dopant atom density, which means
that dopant atoms play an important role both in vortex pinning and in
quasiparticle scattering. In the studied underdoped PrFeAsO_1-y and NdFeAs(O,F)
crystals, there is a background of strong pinning, which we attribute to
spatial variations of the dopant atom density on the scale of a few dozen to
one hundred nm. These variations do not go beyond 5% - we therefore do not find
any evidence for coexistence of the superconducting and the antiferromagnetic
phase. The critical current density in sub-T fields is characterized by the
presence of a peak effect, the location of which in the (B,T)-plane is
consistent with an order-disorder transition of the vortex lattice.Comment: 12 pages, submitted to Phys Rev.
Comparison of Perioperative Outcomes Between Holmium Laser Enucleation of the Prostate and Robot-Assisted Simple Prostatectomy
Objectives: To compare perioperative outcomes for patients undergoing holmium laser enucleation of the prostate (HoLEP) and robotic-assisted simple prostatectomy (RSP) for benign prostatic hypertrophy (BPH).Methods: Patient demographics and perioperative outcomes were compared between 600 patients undergoing HoLEP and 32 patients undergoing RSP at two separate academic institutions between 2008 and 2015.Results: Patients undergoing HoLEP and RSP had comparable ages (71 vs 71, p = 0.96) and baseline American Urological Association Symptom Scores (20 vs 24, p = 0.21). There was no difference in mean specimen weight (96 g vs 110 g, p = 0.15). Mean operative time was reduced in the HoLEP cohort (103 minutes vs 274 minutes, p < 0.001). Patients undergoing HoLEP had lesser decreases in hemoglobin, decreased transfusions rates, shorter hospital stays, and decreased mean duration of catheterization. There was no difference in the rate of complications Clavien grade 3 or greater (p = 0.33).Conclusions: HoLEP and RSP are both efficacious treatments for large gland BPH. In expert hands, HoLEP appears to have a favorable perioperative profile. Further studies are necessary to compare long-term efficacy, cost, and learning curve influences, especially as minimally invasive approaches become more widespread
Non-exponential London penetration depth in RFeAsOF (R=La,Nd) single crystals
The superconducting penetration depth, , has been measured in
RFeAsOF (R=La,Nd) single crystals (R-1111). In Nd-1111, we find
an upturn in upon cooling and attribute it to the paramagnetism of
the Nd ions, similar to the case of the electron-doped cuprate Nd-Ce-Cu-O.
After the correction for paramagnetism, the London penetration depth variation
is found to follow a power-law behavior, at
low temperatures. The same variation of was found in
non-magnetic La-1111 crystals. Analysis of the superfluid density and of
penetration depth anisotropy over the full temperature range is consistent with
two-gap superconductivity. Based on this and on our previous work, we conclude
that both the RFeAsO (1111) and BaFeAs (122) families of pnictide
superconductors exhibit unconventional two-gap superconductivity.Comment: v2 is the same as v1 - error in the arxiv submissio
CD40-targeted adenoviral GM-CSF gene transfer enhances and prolongs the maturation of human CML-derived dendritic cells upon cytokine deprivation
Vaccination with autologous leukaemia-derived dendritic cells (DC) presents an adjuvant treatment option for chronic myeloid leukaemia (CML). Here, we show that high-efficiency CD40-targeted adenoviral gene transfer of GM-CSF to CML-derived DC induces long-lived maturation in the absence of exogenous cytokines and may thus ensure protracted stimulation of CML-specific T cells upon vaccination
Home parenteral nutrition with an omega-3-fatty-acid-enriched MCT/LCT lipid emulsion in patients with chronic intestinal failure (the HOME study):study protocol for a randomized, controlled, multicenter, international clinical trial
BACKGROUND: Home parenteral nutrition (HPN) is a life-preserving therapy for patients with chronic intestinal failure (CIF) indicated for patients who cannot achieve their nutritional requirements by enteral intake. Intravenously administered lipid emulsions (ILEs) are an essential component of HPN, providing energy and essential fatty acids, but can become a risk factor for intestinal-failure-associated liver disease (IFALD). In HPN patients, major effort is taken in the prevention of IFALD. Novel ILEs containing a proportion of omega-3 polyunsaturated fatty acids (n-3 PUFA) could be of benefit, but the data on the use of n-3 PUFA in HPN patients are still limited. METHODS/DESIGN: The HOME study is a prospective, randomized, controlled, double-blind, multicenter, international clinical trial conducted in European hospitals that treat HPN patients. A total of 160 patients (80 per group) will be randomly assigned to receive the n-3 PUFA-enriched medium/long-chain triglyceride (MCT/LCT) ILE (Lipidem/Lipoplus® 200 mg/ml, B. Braun Melsungen AG) or the MCT/LCT ILE (Lipofundin® MCT/LCT/Medialipide® 20%, B. Braun Melsungen AG) for a projected period of 8 weeks. The primary endpoint is the combined change of liver function parameters (total bilirubin, aspartate transaminase and alanine transaminase) from baseline to final visit. Secondary objectives are the further evaluation of the safety and tolerability as well as the efficacy of the ILEs. DISCUSSION: Currently, there are only very few randomized controlled trials (RCTs) investigating the use of ILEs in HPN, and there are very few data at all on the use of n-3 PUFAs. The working hypothesis is that n-3 PUFA-enriched ILE is safe and well-tolerated especially with regard to liver function in patients requiring HPN. The expected outcome is to provide reliable data to support this thesis thanks to a considerable number of CIF patients, consequently to broaden the present evidence on the use of ILEs in HPN. TRIAL REGISTRATION: ClinicalTrials.gov, ID: NCT03282955. Registered on 14 September 2017
Pairing symmetry and properties of iron-based high temperature superconductors
Pairing symmetry is important to indentify the pairing mechanism. The
analysis becomes particularly timely and important for the newly discovered
iron-based multi-orbital superconductors. From group theory point of view we
classified all pairing matrices (in the orbital space) that carry irreducible
representations of the system. The quasiparticle gap falls into three
categories: full, nodal and gapless. The nodal-gap states show conventional
Volovik effect even for on-site pairing. The gapless states are odd in orbital
space, have a negative superfluid density and are therefore unstable. In
connection to experiments we proposed possible pairing states and implications
for the pairing mechanism.Comment: 4 pages, 1 table, 2 figures, polished versio
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