4,573 research outputs found
Radiation content of Conformally flat initial data
We study the radiation of energy and linear momentum emitted to infinity by
the headon collision of binary black holes, starting from rest at a finite
initial separation, in the extreme mass ratio limit. For these configurations
we identify the radiation produced by the initially conformally flat choice of
the three geometry. This identification suggests that the radiated energy and
momentum of headon collisions will not be dominated by the details of the
initial data for evolution of holes from initial proper separations
. For non-headon orbits, where the amount of radiation is orders of
magnitude larger, the conformally flat initial data may provide a relative even
better approximation.Comment: 4 pages, 4 figure
Capillary-Wave Model for the Solidification of Dilute Binary Alloys
Starting from a phase-field description of the isothermal solidification of a
dilute binary alloy, we establish a model where capillary waves of the
solidification front interact with the diffusive concentration field of the
solute. The model does not rely on the sharp-interface assumption, and includes
non-equilibrium effects, relevant in the rapid-growth regime. In many
applications it can be evaluated analytically, culminating in the appearance of
an instability which, interfering with the Mullins-Sekerka instability, is
similar to that, found by Cahn in grain-boundary motion.Comment: 17 pages, 12 figure
Impact of polymorphic variants on the molecular pharmacology of the two-agonist conformations of the human β1-adrenoceptor
β-blockers are widely used to improve symptoms and prolong life in heart disease primarily by inhibiting the actions of endogenous catecholamines at the β1-adrenoceptor. There are two common naturally occurring polymorphisms within the human β1-adrenoceptor sequence: Ser or Gly at position 49 in the N-terminus and Gly or Arg at position 389 in the C-terminus and some clinical studies have suggested that expression of certain variants may be associated with disease and affect response to treatment with β-blockers. The β1-adrenoceptor also exists in two agonist conformations - a high affinity catecholamine conformation and a low affinity secondary agonist conformation. Receptor-effector coupling and intracellular signalling from the different conformations may be affected by the polymorphic variants.
Here, we examine in detail the molecular pharmacology of the β1-adrenoceptor polymorphic variants with respect to ligand affinity, efficacy, activation of the different agonist conformations and signal transduction and determine whether the polymorphic variants do indeed affect this secondary conformation. Stable cell lines expressing the wildtype and polymorphic variants were constructed and receptor pharmacology examined using whole cell binding and intracellular secondary messenger techniques.
There was no difference in affinity for agonists and antagonists at the human wildtype β1-adrenoceptor (Ser49/Gly389) and the polymorphic variants Gly49/Gly389 and Ser49/Arg389. Furthermore, the polymorphic variant receptors both have two active agonist conformations with pharmacological properties similar to the wildtype receptor. Although the polymorphism at position 389 is thought to occur in an intracellular domain important for Gs-coupling, the two agonist conformations of the polymorphic variants stimulate intracellular signalling pathways, including Gs-cAMP intracellular signalling, in a manner very similar to that of the wildtype receptor
Nonexistence of conformally flat slices of the Kerr spacetime
Initial data for black hole collisions are commonly generated using the
Bowen-York approach based on conformally flat 3-geometries. The standard
(constant Boyer-Lindquist time) spatial slices of the Kerr spacetime are not
conformally flat, so that use of the Bowen-York approach is limited in dealing
with rotating holes. We investigate here whether there exist foliations of the
Kerr spacetime that are conformally flat. We limit our considerations to
foliations that are axisymmetric and that smoothly reduce in the Schwarzschild
limit to slices of constant Schwarzschild time. With these restrictions, we
show that no conformally flat slices can exist.Comment: 5 LaTeX pages; no figures; to be submitted to Phys. Rev.
An integrated care pathway for menorrhagia across the primaryâsecondary interface : patients' experience, clinical outcomes, and service utilisation
Background: ââReferralââ characterises a significant area of interaction between primary and secondary care.
Despite advantages, it can be inflexible, and may lead to duplication.
Objective: To examine the outcomes of an integrated model that lends weight to general practitioner (GP)-led
evidence based care.
Design: A prospective, non-random comparison of two services: women attending the new (Bridges) pathway
compared with those attending a consultant-led one-stop menstrual clinic (OSMC). Patientsâ views were
examined using patient career diaries, health and clinical outcomes, and resource utilisation. Follow-up was
for 8 months.
Setting: A large teaching hospital and general practices within one primary care trust (PCT).
Results: Between March 2002 and June 2004, 99 women in the Bridges pathway were compared with 94
women referred to the OSMC by GPs from non-participating PCTs. The patient career diary demonstrated a
significant improvement in the Bridges group for patient information, fitting in at the point of arrangements
made for the patient to attend hospital (ease of access) (p,0.001), choice of doctor (p = 0.020), waiting time
for an appointment (p,0.001), and less ââlimboââ (patient experience of non-coordination between primary
and secondary care) (p,0.001). At 8 months there were no significant differences between the two groups in
surgical and medical treatment rates or in the use of GP clinic appointments. Significantly fewer (traditional)
hospital outpatient appointments were made in the Bridges group than in the OSMC group (p,0.001).
Conclusion: A general practice-led model of integrated care can significantly reduce outpatient attendance
while improving patient experience, and maintaining the quality of care
Acetylene hydrogenation over structured Au-Pd catalysts
Acknowledgements We thank the University of Aberdeen for financial support and Dr K. McManus (University of Aberdeen) for performing preliminary experiments with these samples. Electron microscopy and EDS were performed by RTB at the Electron Microscopy Facility, University of St Andrews.Peer reviewedPostprin
1993 Accounting Hall of Fame induction : Richard T. Baker Accounting Hall of Fame membership [1993]
1993 Accounting Hall of Fame Induction: Richard T. Baker with introduction by Ray J. Groves (Chairman, Ernst & Young); Induction citation by Thomas J. Burns (Deloitte and Touche Professor, The Ohio State University); Response by Richard T. Baker (Chairman Emeritus, Ernst & Whinney
Tattoo ink nanoparticles in skin tissue and fibroblasts
YesTattooing has long been practised in various societies all around the world and is becoming increasingly common and widespread
in the West. Tattoo ink suspensions unquestionably contain pigments composed of nanoparticles, i.e., particles of sub-100 nm
dimensions. It is widely acknowledged that nanoparticles have higher levels of chemical activity than their larger particle equivalents.
However, assessment of the toxicity of tattoo inks has been the subject of little research and ink manufacturers are not obliged
to disclose the exact composition of their products. This study examines tattoo ink particles in two fundamental skin components at
the nanometre level. We use atomic force microscopy and light microscopy to examine cryosections of tattooed skin, exploring the
collagen fibril networks in the dermis that contain ink nanoparticles. Further, we culture fibroblasts in diluted tattoo ink to explore
both the immediate impact of ink pigment on cell viability and also to observe the interaction between particles and the cells
C4: The New Hampshire Spherulitic Rhyolites: Rocks of Importance to Prehistoric Native Americans
Guidebook for field trips in Western Maine and Northern New Hampshire: New England Intercollegiate Geological Conference, p. 305-316
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