743 research outputs found
The Fractionary Schr\"{o}dinger Equation, Green Functions and Ultradistributions
In this work, we generalize previous results about the Fractionary
Schr\"{o}dinger Equation within the formalism of the theory of Tempered
Ultradistributions. Several examples of the use of this theory are given. In
particular we evaluate the Green's function for a free particle in the general
case, for an arbitrary order of the derivative index.Comment: 32 pages. No figure
Low field vortex matter in YBCO: an atomic beam magnetic resonance study
We report measurements of the low field structure of the magnetic vortex
lattice in an untwinned YBCO single-crystal platelet. Measurements were carried
out using a novel atomic beam magnetic resonance (ABMR) technique. For a 10.7 G
field applied parallel to the c-axis of the sample, we find a triangular
lattice with orientational order extending across the entire sample. We find
the triangular lattice to be weakly distorted by the a-b anisotropy of the
material and measure a distortion factor, f = 1.16. Model-experiment
comparisons determine a penetration depth, lambda_ab = 140 (+-20) nm. The paper
includes the first detailed description of the ABMR technique. We discuss both
technical details of the experiment and the modeling used to interpret the
measurements.Comment: 44 pages, 13 figures, submitted to Phys. Rev. B Revision includes
Postscript wrapped figures + minor typo
Governance of Offshore IT Outsourcing at Shell Global Functions IT-BAM Development and Application of a Governance Framework to Improve Outsourcing Relationships
The lack of effective IT governance is widely recognized as a key inhibitor to successful global IT outsourcing relationships. In this study we present the development and application of a governance framework to improve outsourcing relationships. The approach used to developing an IT governance framework includes a meta model and a customization process to fit the framework to the target organization. The IT governance framework consists of four different elements (1) organisational structures, (2) joint processes between in- and outsourcer, (3) responsibilities that link roles to processes and (4) a diverse set of control indicators to measure the success of the relationship. The IT governance framework is put in practice in Shell GFIT BAM, a part of Shell that concluded to have a lack of management control over at least one of their outsourcing relationships. In a workshop the governance framework was used to perform a gap analysis between the current and desired governance. Several gaps were identified in the way roles and responsibilities are assigned and joint processes are set-up. Moreover, this workshop also showed the usefulness and usability of the IT governance framework in structuring, providing input and managing stakeholders in the discussions around IT governance
Potential energy threshold for nano-hillock formation by impact of slow highly charged ions on a CaF(111) surface
We investigate the formation of nano-sized hillocks on the (111) surface of
CaF single crystals by impact of slow highly charged ions. Atomic force
microscopy reveals a surprisingly sharp and well-defined threshold of potential
energy carried into the collision of about 14 keV for hillock formation.
Estimates of the energy density deposited suggest that the threshold is linked
to a solid-liquid phase transition (``melting'') on the nanoscale. With
increasing potential energy, both the basal diameter and the height of the
hillocks increase. The present results reveal a remarkable similarity between
the present predominantly potential-energy driven process and track formation
by the thermal spike of swift ( GeV) heavy ions.Comment: 10 pages, 2 figure
Extragalactic jets on subpc and large scales
Jets can be probed in their innermost regions (d~0.1 pc) through the study of
the relativistically-boosted emission of blazars. On the other extreme of
spatial scales, the study of structure and dynamics of extragalactic
relativistic jets received renewed impulse after the discovery, made by
Chandra, of bright X-ray emission from regions at distances larger than
hundreds of kpc from the central engine. At both scales it is thus possible to
infer some of the basic parameters of the flow (speed, density, magnetic field
intensity, power). After a brief review of the available observational
evidence, I discuss how the comparison between the physical quantities
independently derived at the two scales can be used to shed light on the global
dynamics of the jet, from the innermost regions to the hundreds of kpc scale.Comment: Proceedings of the 5th Stromlo Symposium: Disks, Winds, and Jets -
from Planets to Quasars. Accepted, to be published in Astrophysics & Space
Scienc
Improvement of non-invasive tests of liver steatosis and fibrosis as indicators for non-alcoholic fatty liver disease in type 2 diabetes mellitus patients with elevated cardiovascular risk profile using the PPAR-alpha/gamma agonist aleglitazar
Background: Peroxisome proliferator-activated receptor (PPAR) agonists may have favorable outcomes on non-alcoholic fatty liver disease. This study serves as proof of concept to evaluate whether dual PPAR-alpha/gamma agonists improve non-invasive tests of liver steatosis and fibrosis. Methods: This is a post-hoc analysis of a randomized, double-blind, placebo-controlled, multi-center trial comprising 7226 patients with type 2 diabetes mellitus and recent coronary artery disease randomized to receive aleglitazar, a PPAR-alpha/gamma agonists, or placebo for two years. Main outcomes were change in non-invasive tests for liver steatosis and fibrosis: Liver Fat Score (LFS), Liver Accumulation Product (LAP), Fibrosis-4 (FIB-4), and NAFLD Fibrosis Score (NFS). Results: LFS, LAP and FIB-4 decreased upon treatment, whereas scores in the placebo group remained the same or increased (PCellular mechanisms in basic and clinical gastroenterology and hepatolog
Inversion of Tsallis' q-Fourier Transform and the complex-plane generalization
We introduce a complex q-Fourier transform as a generalization of the (real)
one analyzed in [Milan J. Math. {\bf 76} (2008) 307]. By recourse to tempered
ultradistributions we show that this complex plane-generalization overcomes all
troubles that afflict its real counterpart.Comment: 23 pages, no figure
Critical exponents and equation of state of the three-dimensional Heisenberg universality class
We improve the theoretical estimates of the critical exponents for the
three-dimensional Heisenberg universality class. We find gamma=1.3960(9),
nu=0.7112(5), eta=0.0375(5), alpha=-0.1336(15), beta=0.3689(3), and
delta=4.783(3). We consider an improved lattice phi^4 Hamiltonian with
suppressed leading scaling corrections. Our results are obtained by combining
Monte Carlo simulations based on finite-size scaling methods and
high-temperature expansions. The critical exponents are computed from
high-temperature expansions specialized to the phi^4 improved model. By the
same technique we determine the coefficients of the small-magnetization
expansion of the equation of state. This expansion is extended analytically by
means of approximate parametric representations, obtaining the equation of
state in the whole critical region. We also determine a number of universal
amplitude ratios.Comment: 40 pages, final version. In publication in Phys. Rev.
Pharmacokinetic-pharmacodynamic correlation of imipenem in pediatric burn patients using a bioanalytical liquid chromatographic method
A bioanalytical method was developed and applied to quantify the free imipenem concentrations for pharmacokinetics and PK/PD correlation studies of the dose adjustments required to maintain antimicrobial effectiveness in pediatric burn patients. A reverse-phase Supelcosil LC18 column (250 x 4.6 mm 5 micra), binary mobile phase consisting of 0.01 M, pH 7.0 phosphate buffer and acetonitrile (99:1, v/v), flow rate of 0.8 mL/min, was applied. The method showed good absolute recovery (above 90%), good linearity (0.25-100.0 ”g/mL, r2=0.999), good sensitivity (LLOQ: 0.25 ”g/mL; LLOD: 0.12 ”g/mL) and acceptable stability. Inter/intraday precision values were 7.3/5.9%, and mean accuracy was 92.9%. A bioanalytical method was applied to quantify free drug concentrations in children with burns. Six pediatric burn patients (median 7.0 years old, 27.5 kg), normal renal function, and 33% total burn surface area were prospectively investigated; inhalation injuries were present in 4/6 (67%) of the patients. Plasma monitoring and PK assessments were performed using a serial blood sample collection for each set, totaling 10 sets. The PK/PD target attained (40%T>MIC) for each minimum inhibitory concentration (MIC: 0.5, 1.0, 2.0, 4.0 mg/L) occurred at a percentage higher than 80% of the sets investigated and 100% after dose adjustment. In conclusion, the purification of plasma samples using an ultrafiltration technique followed by quantification of imipenem plasma measurements using the LC method is quite simple, useful, and requires small volumes for blood sampling. In addition, a small amount of plasma (0.25 mL) is needed to guarantee drug effectiveness in pediatric burn patients. There is also a low risk of neurotoxicity, which is important because pharmacokinetics are unpredictable in these critical patients with severe hospital infection. Finally, the PK/PD target was attained for imipenem in the control of sepsis in pediatric patients with burns.</p
- âŠ