722 research outputs found
High Body Mass Index in Adolescent Girls Precedes Psoriasis Hospitalization
Psoriasis is associated with being overweight, but the temporal relationship is not known. This historical cohort study tested whether severe psoriasis resulting in hospitalization in adulthood was preceded by excess increase in age-adjusted body mass index, a known risk factor in childhood for being overweight in adulthood. The study cohort was based on the Copenhagen School Health Records Register, birth years 1930 to 1984 (309,152 schoolchildren). Cases were found through the Danish National Patient Register for the period 1977 to 2001. A total of 1074 (0.36%) of the schoolchildren were identified as having psoriasis, with at least one hospital admission. Multivariate analysis demonstrated an association between excess increase in body mass index and psoriasis in females only. Being overweight in adolescence was the main factor behind this observation. The female group showed a significant association between psoriasis and body mass index at ages 12 (p=0.028) and 13 years (p=0.010). This was not the case for males or for body mass index measured at ages 11 years and below
Founding quantum theory on the basis of consciousness
In the present work, quantum theory is founded on the framework of
consciousness, in contrast to earlier suggestions that consciousness might be
understood starting from quantum theory. The notion of streams of
consciousness, usually restricted to conscious beings, is extended to the
notion of a Universal/Global stream of conscious flow of ordered events. The
streams of conscious events which we experience constitute sub-streams of the
Universal stream. Our postulated ontological character of consciousness also
consists of an operator which acts on a state of potential consciousness to
create or modify the likelihoods for later events to occur and become part of
the Universal conscious flow. A generalized process of measurement-perception
is introduced, where the operation of consciousness brings into existence, from
a state of potentiality, the event in consciousness. This is mathematically
represented by (a) an operator acting on the state of potential-consciousness
before an actual event arises in consciousness and (b) the reflecting of the
result of this operation back onto the state of potential-consciousness for
comparison in order for the event to arise in consciousness. Beginning from our
postulated ontology that consciousness is primary and from the most elementary
conscious contents, such as perception of periodic change and motion, quantum
theory follows naturally as the description of the conscious experience.Comment: 41 pages, 3 figures. To be published in Foundations of Physics, Vol
36 (6) (June 2006), published online at
http://dx.doi.org/10.1007/s10701-006-9049-
Comparing initial-data sets for binary black holes
We compare the results of constructing binary black hole initial data with
three different decompositions of the constraint equations of general
relativity. For each decomposition we compute the initial data using a
superposition of two Kerr-Schild black holes to fix the freely specifiable
data. We find that these initial-data sets differ significantly, with the ADM
energy varying by as much as 5% of the total mass. We find that all
initial-data sets currently used for evolutions might contain unphysical
gravitational radiation of the order of several percent of the total mass. This
is comparable to the amount of gravitational-wave energy observed during the
evolved collision. More astrophysically realistic initial data will require
more careful choices of the freely specifiable data and boundary conditions for
both the metric and extrinsic curvature. However, we find that the choice of
extrinsic curvature affects the resulting data sets more strongly than the
choice of conformal metric.Comment: 18 pages, 12 figures, accepted for publication in Phys. Rev.
Manganese-Enhanced Magnetic Resonance Imaging in Takotsubo Syndrome
Acknowledgments The authors thank the Edinburgh Imaging Facility. Sources of Funding This work and T. Singh, S. Joshi, and Drs Dweck and Newby are supported by the British Heart Foundation (grants FS/17/19/32641, CS/17/1/32445, RG/16/10/32375, RE/18/5/34216, FS/ICRF/20/26002, and FS/SCRF/21/32010). T. Singh is supported by the Medical Research Council (grant MR/T029153/1). Dr Newby is the recipient of a Wellcome Trust Senior Investigator Award (WT103782AIA). Dr McCann is supported by an NIHR Research Professorship (08-2017-ST2-007). The Edinburgh Clinical Research Facilities and Edinburgh Imaging Facility are supported by the National Health Service Research Scotland through the National Health Service Lothian Health Board.Peer reviewe
LABORATORY INVESTIGATIONS IN SUPPORT OF FLUID BED FLUORIDE VOLATILITY PROCESSES. PART I. THE FLUORINATION OF URANIUM DIOXIDE-PLUTONIUM DIOXIDE SOLID SOLUTIONS
Work in the development of fluid-bed fluoride volatility processes is described. In these processes, uranium and plutonium in spent nuclear fuels are converted into hexafluoride compounds in a fluid-bed reactor. The uranium and plutonium hexafluorides are volatile and can be separated from fission products, cladding, and alloying materials by techniques such as vaporization and distillation. The experimental work was directed toward devising a fluorination procedure for uranium and plutonium dioxides which would result in a high degree of removal of uranium and plutonium as hexafluorides. In these experiments synthetic mixtures made up to simulate a charge for a fluidized bed reactor (100 kg U, 0.4 kg Pu, approximates 1 kg F.P., and 30 kg inert solids) were used. High-purity recrystallized alumina was found to be a suitable material for use as the fluidized inert solid. After a 10-hr fluorination period at 450 deg C, the concentrations of residual uranium and plutonium on the alumina were 0.01 and 0.03 wt%, respectively. A reaction temperature of 450 deg C was found to be optimum, since experiments at 500 and 550 deg C resulted in plutonium retentions on the alumina of 0.060 and 0.090 wt%, respectively. At all these temperatures, the residual uranium content of the residue was less than 0.01 wt%. When fission product element oxides, in quantities that would be expected in a Dresden-type fuel after 100,000 Mwd/ton burnup and 30 days of cooling, were added to the uranium dioxide-plutonium dioxide-- alumina and the mixture was fluorinated at 450 deg C for 10 hr, the concentration of plutonium on the alumina increased to a value of 0.065 U%. Additional recovery of the plutonium retained on the alumina was obtained by either pyrohydrolysis followed by refluorination at 450 deg C for 10 hr, or by refluorination alone at 550 deg C for 10 hr. These procedures reduced the residual plutonium content of the alumina to less than 0.02 wt%. Experiments were also performed to determine the feasibility of using the same batch of alumina as the inert solid for the fluorinations of five batches of the urania--plutonia solid solution. Experiments were performed in which the solid solution of plutonium dioxide in uranium dioxide was oxidized prior to fluorination. The oxidation resulted in a powdered mixture of uranosic oxide and plutonium dioxide. Fluorination of this oxide mixture in alumina resulted in the removal of essentially all of the uranium in a reaction time of 2 hr at 450 deg C when 10 vol% fluorine was used. When this fluorination was followed by a second fluorination period of 5 hr at 550 deg C with 75 vol% fluorine, the plutonium content of the alumina was 0.011 wt%. When both fluorination periods were extended to 10 hr each, the retention of plutonium was 0.007 wt%, which corresponded to a removal of 99.5% of the plutonium contained in the solid mixture. During the first part of the fluorination period, in which the major portion of the uranium is removed from the mixture of uranium dioxide, plutonium dioxide, alumina, and representative fission product element oxides, a low ternperature (450 deg C) and a low concentration of fluorine (10 vol% fluorine in nitrogen) are desirable. However, in order to remove the plutonium efficiently during the last portion of the fluorination period, it is desirable to use a higher temperature (550 deg C) and a higher fluorine content of the gas mixture (75 vol% fluorine in nitrogen). (auth
Circular orbits of corotating binary black holes: comparison between analytical and numerical results
We compare recent numerical results, obtained within a ``helical Killing
vector'' (HKV) approach, on circular orbits of corotating binary black holes to
the analytical predictions made by the effective one body (EOB) method (which
has been recently extended to the case of spinning bodies). On the scale of the
differences between the results obtained by different numerical methods, we
find good agreement between numerical data and analytical predictions for
several invariant functions describing the dynamical properties of circular
orbits. This agreement is robust against the post-Newtonian accuracy used for
the analytical estimates, as well as under choices of resummation method for
the EOB ``effective potential'', and gets better as one uses a higher
post-Newtonian accuracy. These findings open the way to a significant
``merging'' of analytical and numerical methods, i.e. to matching an EOB-based
analytical description of the (early and late) inspiral, up to the beginning of
the plunge, to a numerical description of the plunge and merger. We illustrate
also the ``flexibility'' of the EOB approach, i.e. the possibility of
determining some ``best fit'' values for the analytical parameters by
comparison with numerical data.Comment: Minor revisions, accepted for publication in Phys. Rev. D, 19 pages,
6 figure
Time-symmetric initial data for binary black holes in numerical relativity
We look for physically realistic initial data in numerical relativity which
are in agreement with post-Newtonian approximations. We propose a particular
solution of the time-symmetric constraint equation, appropriate to two
momentarily static black holes, in the form of a conformal decomposition of the
spatial metric. This solution is isometric to the post-Newtonian metric up to
the 2PN order. It represents a non-linear deformation of the solution of Brill
and Lindquist, i.e. an asymptotically flat region is connected to two
asymptotically flat (in a certain weak sense) sheets, that are the images of
the two singularities through appropriate inversion transformations. The total
ADM mass M as well as the individual masses m_1 and m_2 (when they exist) are
computed by surface integrals performed at infinity. Using second order
perturbation theory on the Brill-Lindquist background, we prove that the
binary's interacting mass-energy M-m_1-m_2 is well-defined at the 2PN order and
in agreement with the known post-Newtonian result.Comment: 27 pages, to appear in Phys. Rev.
Fusion of secretory vesicles isolated from rat liver
Secretory vesicles isolated from rat liver were found to fuse after exposure to Ca2+. Vescle fusion is characterized by the occurrence of twinned vesicles with a continuous cleavage plane between two vesicles in freeze-fracture electron microscopy. The number of fused vesicles increases with increasing Ca2+-concentrations and is half maximal around 10â6 m. Other divalent cations (Ba2+, Sr2+, and Mg2+) were ineffective. Mg2+ inhibits Ca2+-induced fusion. Therefore, the fusion of secretory vesiclesin vitro is Ca2+ specific and exhibits properties similar to the exocytotic process of various secretory cells.
Various substances affecting secretionin vivo (microtubular inhibitors, local anethetics, ionophores) were tested for their effect on membrane fusion in our system.
The fusion of isolated secretory vesicles from liver was found to differ from that of pure phospholipid membranes in its temperature dependence, in its much lower requirement for Ca2+, and in its Ca2+-specificity. Chemical and enzymatic modifications of the vesicle membrane indicate that glycoproteins may account for these differences
Menus for Feeding Black Holes
Black holes are the ultimate prisons of the Universe, regions of spacetime
where the enormous gravity prohibits matter or even light to escape to
infinity. Yet, matter falling toward the black holes may shine spectacularly,
generating the strongest source of radiation. These sources provide us with
astrophysical laboratories of extreme physical conditions that cannot be
realized on Earth. This chapter offers a review of the basic menus for feeding
matter onto black holes and discusses their observational implications.Comment: 27 pages. Accepted for publication in Space Science Reviews. Also to
appear in hard cover in the Space Sciences Series of ISSI "The Physics of
Accretion onto Black Holes" (Springer Publisher
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