7,150 research outputs found
Sequential comparison of tiotropium to high-dose ipratropium in patients with chronic obstructive pulmonary disease in a practice setting
Umair Gauhar, Mark Dransfield, J Allen D CooperPulmonary Section, Birmingham Veterans Affairs Medical Center and Division of Allergy, Pulmonary and Critical Medicine University of Alabama at Birmingham, AL, USAObjective: To determine the effect of changing anticholinergic therapy in patients with COPD from ipratropium to tiotropium on pulmonary function.Methods: We examined records of patients prescribed high-dose ipratropium, who were subsequently converted to tiotropium. Spirometric values were obtained within 2 days of the change in medication and after 56 to 224 days of the switch to tiotropium.Results: 15 subjects were documented to have filled a prescription for ipratropium-containing medications the month prior to the change. Medication compliance over the 6 months prior to the switch in these patients was 72% ± 31% (mean ± SD) for ipratropium compared to 87% ± 14% for tiotropium over the 6-month period after the switch (P = 0.1). FEV1 improved from 1.12 ± 0.39 L at baseline to 1.37 ± 0.49 L after the change to tiotropium (P = 0.01). FVC also improved from 2.45 ± 0.73 L at baseline to 2.72 ± 0.69 L after the change (P = 0.04). Maximal voluntary ventilation was also increased from 39.67 ± 10.7 L/min to 45.13 ± 15.8 L/min (P = 0.045).Conclusions: We conclude that replacing high-dose ipratropium with tiotropium therapy significantly improves pulmonary function in a clinical setting.Keywords: ipratropium, tiotropium, COPD, pulmonary function, exacerbation rat
Isotope Effect in the Superfluid Density of HTS Cuprates: Stripes, Pseudogap and Impurities
Underdoped cuprates exhibit a normal-state pseudogap, and their spins and
doped carriers tend to spatially separate into 1- or 2-D stripes. Some view
these as central to superconductivity, others as peripheral and merely
competing. Using LaSrCuZnO we show that an oxygen
isotope effect in and in the superfluid density can be used to
distinguish between the roles of stripes and pseudogap and also to detect the
presence of impurity scattering. We conclude that stripes and pseudogap are
distinct, and both compete and coexist with superconductivity.Comment: Revised submission to PRL with added appendix on a possible isotope
effect in the effective mass, 4 pages, 3 figure
Tachyon Effective Dynamics and de Sitter Vacua
We show that the DBI action for the singlet sector of the tachyon in
two-dimensional string theory has a SL(2,R) symmetry, a real-time counterpart
of the ground ring. The action can be rewritten as that of point particles
moving in a de Sitter space, whose coordinates are given by the value of the
eigenvalue and time. The symmetry then manifests as the isometry group of de
Sitter space in two dimensions. We use this fact to write the collective field
theory for a large number of branes, which has a natural interpretation as a
fermion field in this de Sitter space. After spending some time building
geometrical insight on facts about the condensation process, the state
corresponding to a sD-brane is identified and standard results in quantum field
theory in curved space-time are used to compute the backreaction of the thermal
background.Comment: 28 pages, 1 eps figure. Uses graphicx, setspace. v2:corrected typos,
added references, clarified discussion on backreactio
Thermodynamic functions within the van Hove BCS model: Symmetry mixing effects
All the new layer perovskite superconductors seem to show a phenomenon of
symmetry mixing with repect to the order parameter. An analysis of the
different alternative of mixing and how far could them be presented is carried
out. For the particular case of s+id symmetry of the gap, the temperature
dependence of the specific heat () and the thermodynamic critical
magnetic field () are calculated. A double peak transition is observed
on in the mixed regime while the single peak behavior is recovered
for a purely symmetric state (s or d). presents a quadratic law at low
tempeartures for a d-wave gap and for the s-wave one the typical exponential
attenuation. The temperature dependence of shows a clear phase
transition of second order at temperatures where the d-wave component becomes
negligible. A comparison with other results and experiments is done.Comment: Revised version and accepted to be published in Physica
Learning to prescribe - pharmacists' experiences of supplementary prescribing training in England
Background: The introduction of non-medical prescribing for professions such as pharmacy and nursing in
recent years offers additional responsibilities and opportunities but attendant training issues. In the UK and in contrast to some international models, becoming a non-medical prescriber involves the completion of an
accredited training course offered by many higher education institutions, where the skills and knowledge
necessary for prescribing are learnt.
Aims: to explore pharmacists' perceptions and experiences of learning to prescribe on supplementary prescribing (SP) courses, particularly in relation to inter-professional learning, course content and subsequent use of prescribing in practice.
Methods: A postal questionnaire survey was sent to all 808 SP registered pharmacists in England in April 2007,
exploring demographic, training, prescribing, safety culture and general perceptions of SP.
Results: After one follow-up, 411 (51%) of pharmacists responded. 82% agreed SP training was useful, 58%
agreed courses provided appropriate knowledge and 62% agreed that the necessary prescribing skills were gained.
Clinical examination, consultation skills training and practical experience with doctors were valued highly;
pharmacology training and some aspects of course delivery were criticised. Mixed views on inter-professional
learning were reported – insights into other professions being valued but knowledge and skills differences
considered problematic. 67% believed SP and recent independent prescribing (IP) should be taught together, with more diagnostic training wanted; few pharmacists trained in IP, but many were training or intending to train. There was no association between pharmacists' attitudes towards prescribing training and when they undertook training between 2004 and 2007 but earlier cohorts were more likely to be using supplementary prescribing in practice.
Conclusion: Pharmacists appeared to value their SP training and suggested improvements that could inform
future courses. The benefits of inter-professional learning, however, may conflict with providing professionspecific training. SP training may be perceived to be an instrumental 'stepping stone' in pharmacists' professional project of gaining full IP status
Attractor states and infrared scaling in de Sitter space
The renormalized expectation value of the energy-momentum tensor for a scalar
field with any mass m and curvature coupling xi is studied for an arbitrary
homogeneous and isotropic physical initial state in de Sitter spacetime. We
prove quite generally that has a fixed point attractor behavior at
late times, which depends only on m and xi, for any fourth order adiabatic
state that is infrared finite. Specifically, when m^2 + xi R > 0,
approaches the Bunch-Davies de Sitter invariant value at late times,
independently of the initial state. When m = xi = 0, it approaches instead the
de Sitter invariant Allen-Folacci value. When m = 0 and xi \ge 0 we show that
this state independent asymptotic value of the energy-momentum tensor is
proportional to the conserved geometrical tensor (3)H_{ab}, which is related to
the behavior of the quantum effective action of the scalar field under global
Weyl rescaling. This relationship serves to generalize the definition of the
trace anomaly in the infrared for massless, non-conformal fields. In the case
m^2 + xi R = 0, but m and xi separately different from zero, grows
linearly with cosmic time at late times. For most values of m and xi in the
tachyonic cases, m^2 + xi R grows exponentially at late cosmic
times for all physically admissable initial states.Comment: 30 pages, 6 figures, 46 kB tar.gz fil
Strong electron-phonon coupling in delta-phase stabilized Pu
Heat capacity measurements of the delta-phase stabilized alloy Pu-Al suggest
that strong electron-phonon coupling is required to explain the moderate
renormalization of the electronic density of states near the Fermi energy. We
calculate the heat capacity contributions from the lattice and electronic
degrees of freedom as well as from the electron-lattice coupling term and find
good overall agreement between experiment and theory assuming a dimensionless
electron-phonon coupling parameter of order unity, lambda ~ 0.8. This large
electron-phonon coupling parameter is comparable to reported values in other
superconducting metals with face-centered cubic crystal structure, for example,
Pd (lambda ~ 0.7) and Pb (lambda ~ 1.5). Further, our analysis shows evidence
of a sizable residual low-temperature entropy contribution, S_{res} ~ 0.4 k_B
(per atom). We can fit the residual specific heat to a two-level system.
Therefore, we speculate that the observed residual entropy originates from
crystal-electric field effects of the Pu atoms or from self-irradiation induced
defects frozen in at low temperatures.Comment: 9 pages, 11 figures, to appear in Phys. Rev.
Plaquette-singlet solid state and topological hidden order in spin-1 antiferromagnetic Heisenberg ladder
Ground-state properties of the spin-1 two-leg antiferromagnetic ladder are
investigated precisely by means of the quantum Monte Carlo method. It is found
that the correlation length along the chains and the spin gap both remain
finite regardless of the strength of interchain coupling, i.e., the Haldane
state and the spin-1 dimer state are connected smoothly without any quantum
phase transitions between them. We propose a plaquette-singlet solid state,
which qualitatively describes the ground state of the spin-1 ladder quite well,
and also a corresponding topological hidden order parameter. It is shown
numerically that the new hidden order parameter remains finite up to the dimer
limit, though the conventional string order defined on each chain vanishes
immediately when infinitesimal interchain coupling is introduced.Comment: RevTeX, 10 pages, 9 figure
Non-Perturbative Quantum Dynamics of a New Inflation Model
We consider an O(N) model coupled self-consistently to gravity in the
semiclassical approximation, where the field is subject to `new inflation' type
initial conditions. We study the dynamics self-consistently and
non-perturbatively with non-equilibrium field theory methods in the large N
limit. We find that spinodal instabilities drive the growth of
non-perturbatively large quantum fluctuations which shut off the inflationary
growth of the scale factor. We find that a very specific combination of these
large fluctuations plus the inflaton zero mode assemble into a new effective
field. This new field behaves classically and it is the object which actually
rolls down. We show how this reinterpretation saves the standard picture of how
metric perturbations are generated during inflation and that the spinodal
growth of fluctuations dominates the time dependence of the Bardeen variable
for superhorizon modes during inflation. We compute the amplitude and index for
the spectrum of scalar density and tensor perturbations and argue that in all
models of this type the spinodal instabilities are responsible for a `red'
spectrum of primordial scalar density perturbations. A criterion for the
validity of these models is provided and contact with the reconstruction
program is established validating some of the results within a non-perturbative
framework. The decoherence aspects and the quantum to classical transition
through inflation are studied in detail by following the full evolution of the
density matrix and relating the classicality of cosmological perturbations to
that of long-wavelength matter fluctuations.Comment: 39 pages, 12 epsf figure
Charge transfer fluctuation, wave superconductivity, and the Raman phonon in the Cuprates: A detailed analysis
The Raman spectrum of the phonon in the superconducting cuprate
materials is investigated theoretically in detail in both the normal and
superconducting phases, and is contrasted with that of the phonon. A
mechanism involving the charge transfer fluctuation between the two oxygen ions
in the CuO plane coupled to the crystal field perpendicular to the plane is
discussed and the resulting electron-phonon coupling is evaluated. Depending on
the symmetry of the phonon the weight of different parts of the Fermi surface
in the coupling is different. This provides the opportunity to obtain
information on the superconducting gap function at certain parts of the Fermi
surface. The lineshape of the phonon is then analyzed in detail both in the
normal and superconducting states. The Fano lineshape is calculated in the
normal state and the change of the linewidth with temperature below T is
investigated for a pairing symmetry. Excellent agreement is
obtained for the phonon lineshape in YBaCuO. These
experiments, however, can not distinguish between and a
highly anisotropic -wave pairing.Comment: Revtex, 21 pages + 4 postscript figures appended, tp
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