3,135 research outputs found
Angular reduction in multiparticle matrix elements
A general method for the reduction of coupled spherical harmonic products is
presented. When the total angular coupling is zero, the reduction leads to an
explicitly real expression in the scalar products within the unit vector
arguments of the spherical harmonics. For non-scalar couplings, the reduction
gives Cartesian tensor forms for the spherical harmonic products, with tensors
built from the physical vectors in the original expression. The reduction for
arbitrary couplings is given in closed form, making it amenable to symbolic
manipulation on a computer. The final expressions do not depend on a special
choice of coordinate axes, nor do they contain azimuthal quantum number
summations, nor do they have complex tensor terms for couplings to a scalar.
Consequently, they are easily interpretable from the properties of the physical
vectors they contain.Comment: This version contains added comments and typographical corrections to
the original article. Now 27 pages, 0 figure
Calculation of lactate disappearance with isotopic tracers using tissue lactate specific radioactivity
On Hilberg's Law and Its Links with Guiraud's Law
Hilberg (1990) supposed that finite-order excess entropy of a random human
text is proportional to the square root of the text length. Assuming that
Hilberg's hypothesis is true, we derive Guiraud's law, which states that the
number of word types in a text is greater than proportional to the square root
of the text length. Our derivation is based on some mathematical conjecture in
coding theory and on several experiments suggesting that words can be defined
approximately as the nonterminals of the shortest context-free grammar for the
text. Such operational definition of words can be applied even to texts
deprived of spaces, which do not allow for Mandelbrot's ``intermittent
silence'' explanation of Zipf's and Guiraud's laws. In contrast to
Mandelbrot's, our model assumes some probabilistic long-memory effects in human
narration and might be capable of explaining Menzerath's law.Comment: To appear in Journal of Quantitative Linguistic
Luteinizing Hormone-Releasing Hormone in the Vomeronasal System and Terminal Nerve of the Hamster a
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74742/1/j.1749-6632.1987.tb36300.x.pd
Population coding by globally coupled phase oscillators
A system of globally coupled phase oscillators subject to an external input
is considered as a simple model of neural circuits coding external stimulus.
The information coding efficiency of the system in its asynchronous state is
quantified using Fisher information. The effect of coupling and noise on the
information coding efficiency in the stationary state is analyzed. The
relaxation process of the system after the presentation of an external input is
also studied. It is found that the information coding efficiency exhibits a
large transient increase before the system relaxes to the final stationary
state.Comment: 7 pages, 9 figures, revised version, new figures added, to appear in
JPSJ Vol 75, No.
Model Calculations for the Two-Fragment Electro-Disintegration of He
Differential cross sections for the electro-disintegration process are calculated, using a model in which
the final state interaction is included by means of a nucleon-nucleus (3+1)
potential constructed via Marchenko inversion. The required bound-state wave
functions are calculated within the integrodifferential equation approach
(IDEA). In our model the important condition that the initial bound state and
the final scattering state are orthogonal is fulfilled. The sensitivity of the
cross section to the input interaction in certain kinematical regions
is investigated. The approach adopted could be useful in reactions involving
few cluster systems where effective interactions are not well known and exact
methods are presently unavailable. Although, our Plane-Wave Impulse
Approximation results exhibit, similarly to other calculations, a dip in the
five-fold differential cross-section around a missing momentum of , it is argued that this is an artifact of the omission of re-scattering
four-nucleon processes.Comment: 16 pages, 6 figures, accepted for publication by Phys.Rev.
Risk of cardiovascular disease and total mortality in adults with type 1 diabetes: Scottish registry linkage study
<p>Background: Randomized controlled trials have shown the importance of tight glucose control in type 1 diabetes (T1DM), but few recent studies have evaluated the risk of cardiovascular disease (CVD) and all-cause mortality among adults with T1DM. We evaluated these risks in adults with T1DM compared with the non-diabetic population in a nationwide study from Scotland and examined control of CVD risk factors in those with T1DM.</p>
<p>Methods and Findings: The Scottish Care Information-Diabetes Collaboration database was used to identify all people registered with T1DM and aged â„20 years in 2005â2007 and to provide risk factor data. Major CVD events and deaths were obtained from the national hospital admissions database and death register. The age-adjusted incidence rate ratio (IRR) for CVD and mortality in T1DM (n = 21,789) versus the non-diabetic population (3.96 million) was estimated using Poisson regression. The age-adjusted IRR for first CVD event associated with T1DM versus the non-diabetic population was higher in women (3.0: 95% CI 2.4â3.8, p<0.001) than men (2.3: 2.0â2.7, p<0.001) while the IRR for all-cause mortality associated with T1DM was comparable at 2.6 (2.2â3.0, p<0.001) in men and 2.7 (2.2â3.4, p<0.001) in women. Between 2005â2007, among individuals with T1DM, 34 of 123 deaths among 10,173 who were <40 years and 37 of 907 deaths among 12,739 who were â„40 years had an underlying cause of death of coma or diabetic ketoacidosis. Among individuals 60â69 years, approximately three extra deaths per 100 per year occurred among men with T1DM (28.51/1,000 person years at risk), and two per 100 per year for women (17.99/1,000 person years at risk). 28% of those with T1DM were current smokers, 13% achieved target HbA1c of <7% and 37% had very poor (â„9%) glycaemic control. Among those aged â„40, 37% had blood pressures above even conservative targets (â„140/90 mmHg) and 39% of those â„40 years were not on a statin. Although many of these risk factors were comparable to those previously reported in other developed countries, CVD and mortality rates may not be generalizable to other countries. Limitations included lack of information on the specific insulin therapy used.</p>
<p>Conclusions: Although the relative risks for CVD and total mortality associated with T1DM in this population have declined relative to earlier studies, T1DM continues to be associated with higher CVD and death rates than the non-diabetic population. Risk factor management should be improved to further reduce risk but better treatment approaches for achieving good glycaemic control are badly needed.</p>
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