1,107 research outputs found
Proton Decay from Excited States in Spherical Nuclei
Based on a single particle model which describes the time evolution of the
wave function during tunneling across a one dimensional potential barrier we
study the proton decay of Pb from excited states with non-vanishing
angular momentum . Several quantities of interest in this process like
the decay rate , the period of oscillation , the transient
time , the tunneling time and the average value of the proton
packet position are computed and compared with the WKB results.Comment: 12 pages, 4 figure
Energy averages and fluctuations in the decay out of superdeformed bands
We derive analytic formulae for the energy average (including the energy
average of the fluctuation contribution) and variance of the intraband decay
intensity of a superdeformed band. Our results may be expressed in terms of
three dimensionless variables: , ,
and . Here is
the spreading width for the mixing of a superdeformed (SD) state with the
normally deformed (ND) states whose spin is the same as 's. The
have mean level spacing and mean electromagnetic decay width
whilst has electromagnetic decay width .
The average decay intensity may be expressed solely in terms of the variables
and or, analogously to statistical
nuclear reaction theory, in terms of the transmission coefficients and
describing transmission from the to the SD band via and
to lower ND states.
The variance of the decay intensity, in analogy with Ericson's theory of
cross section fluctuations depends on an additional variable, the correlation
length
\Gamma_N/(\Gamma_S+\Gamma^{\downarrow})=\frac{d}{2\pi}T_N/(\Gamma_S+\Gamma^{\d
ownarrow}). This suggests that analysis of an experimentally obtained variance
could yield the mean level spacing as does analysis of the cross section
autocorrelation function in compound nuclear reactions.
We compare our results with those of Gu and Weidenm\"uller.Comment: revtex4, 14 pages, 4 figures, to appear in Physical Review
Diagnosis of the neuronal ceroid lipofuscinoses: An update
AbstractFor the majority of families affected by one of the neuronal ceroid lipofuscinoses (NCLs), a biochemical and/or genetic diagnosis can be achieved. In an individual case this information not only increases understanding of the condition but also may influence treatment choices and options. The presenting clinical features prompt initial investigation and also guide clinical care. The clinical labels “infantile NCL”, “late infantile NCL” and “juvenile NCL”, therefore remain useful in practice. In unusual or atypical cases ultra-structural analysis of white blood cells or other tissue samples enables planning and prioritisation of biochemical and genetic tests.This review describes current methods available to achieve clinical, pathological, biochemical and genetic diagnosis in children presenting with symptoms suggestive of one of the NCLs
A measure of majorisation emerging from single-shot statistical mechanics
The use of the von Neumann entropy in formulating the laws of thermodynamics
has recently been challenged. It is associated with the average work whereas
the work guaranteed to be extracted in any single run of an experiment is the
more interesting quantity in general. We show that an expression that
quantifies majorisation determines the optimal guaranteed work. We argue it
should therefore be the central quantity of statistical mechanics, rather than
the von Neumann entropy. In the limit of many identical and independent
subsystems (asymptotic i.i.d) the von Neumann entropy expressions are recovered
but in the non-equilbrium regime the optimal guaranteed work can be radically
different to the optimal average. Moreover our measure of majorisation governs
which evolutions can be realized via thermal interactions, whereas the
nondecrease of the von Neumann entropy is not sufficiently restrictive. Our
results are inspired by single-shot information theory.Comment: 54 pages (15+39), 9 figures. Changed title / changed presentation,
same main results / added minor result on pure bipartite state entanglement
(appendix G) / near to published versio
Calculation of the photoionization with de-excitation cross sections of He and helium-like ions
We discuss the results of the calculation of the photoionization with
de-excitation of excited He and helium-like ions Li and B at high
but non-relativistic photon energies . Several lower and
states are considered. We present and analyze the ratios
of the cross sections of photoionization with de-excitation,
, and of the photo-ionization with excitation,
. The dependence of on the excitation
of the target object and the charge of its nucleus is presented. Apart to
theoretical interest, results obtained can be verified using such long living
excited state as of He.Comment: 10 pages, 6 table
Local Spectral Density for a Periodically Driven System of Coupled Quantum States with Strong Imperfection in Unperturbed Energies
A random matrix theory approach is applied in order to analyze the
localization properties of local spectral density for a generic system of
coupled quantum states with strong static imperfection in the unperturbed
energy levels. The system is excited by an external periodic field, the
temporal profile of which is close to monochromatic one. The shape of local
spectral density is shown to be well described by the contour obtained from a
relevant model of periodically driven two-states system with irreversible
losses to an external thermal bath. The shape width and the inverse
participation ratio are determined as functions both of the Rabi frequency and
of parameters specifying the localization effect for our system in the absence
of external field.Comment: 6 pages, 5 figures, submitted to Optics and Spectroscop
Age and sex differences in cause-specific excess mortality and years of life lost associated with COVID-19 infection in the Swedish population
Background Estimating excess mortality and years of life lost (YLL) attributed to coronavirus disease 19 (COVID-19) infection provides a comprehensive picture of the mortality burden on society. We aimed to estimate the impact of the COVID-19 pandemic on age- and sex-specific excess mortality and YLL in Sweden during the first 17 months of the pandemic. Methods In this population-based observational study, we calculated age- and sex-specific excess all-cause mortality and excess YLL during 2020 and the first 5 months of 2021 and cause-specific death [deaths from cardiovascular disease (CVD), cancer, other causes and deaths excluding COVID-19] in 2020 compared with an average baseline for 2017-19 in the whole Swedish population. Results COVID-19 deaths contributed 9.9% of total deaths (98 441 deaths, 960 305 YLL) in 2020, accounting for 75 151 YLL (7.7 YLL/death). There were 2672 (5.7%) and 1408 (3.0%) excess deaths, and 19 141 (3.8%) and 3596 (0.8%) excess YLL in men and women, respectively. Men aged 65-110 years and women aged 75-110 years were the greatest contributors. Fewer deaths and YLL from CVD, cancer and other causes were observed in 2020 compared with the baseline adjusted to the population size in 2020. Conclusions Compared with the baseline, excess mortality and YLL from all causes were experienced in Sweden during 2020, with a higher excess observed in men than in women, indicating that more men died at a younger age while more women died at older ages than expected. A notable reduction in deaths and YLL due to CVD suggests a displacement effect from CVD to COVID-19
Suggestive Linkage Detected for Blood Pressure Related Traits on 2q and 22q in the Population on the Samoan Islands
Background
High blood pressure or hypertension is a major risk factor involved in the development of cardiovascular diseases. We conducted genome-wide variance component linkage analyses to search for loci influencing five blood pressure related traits including the quantitative traits systolic blood pressure (SBP), diastolic blood pressure (DBP) and pulse pressure (PP), the dichotomous trait hypertension (HT) and the bivariate quantitative trait SBP-DBP in families residing in American Samoa and Samoa, as well as in the combined sample from the two polities. We adjusted the traits for a number of environmental covariates such as smoking, alcohol consumption, physical activity and material life style. Results
We found suggestive univariate linkage for SBP on chromosome 2q35-q37 (LOD 2.4) and for PP on chromosome 22q13 (LOD 2.2), two chromosomal regions that recently have been associated with SBP and PP, respectively. Conclusion
We have detected additional evidence for a recently reported locus associated with SBP on chromosome 2q and a susceptibility locus for PP on chromosome 22q. However, differences observed between the results from our three partly overlapping genetically homogenous study samples from the Samoan islands suggest that additional studies should be performed in order to verify these results
Metabolic effects of darunavir/ritonavir versus atazanavir/ritonavir in treatment-naive, HIV Type 1-infected subjects over 48 weeks
We assessed metabolic changes for darunavir/ritonavir (DRV/r) once daily (qd) versus atazanavir/ritonavir (ATV/r) qd with fixed-dose tenofovir/emtricitabine. This was a phase 4, multicenter, open-label, randomized exploratory study. Treatment-naive, HIV-1-infected adults received DRV/r 800/100 mg qd or ATV/r 300/100 mg qd, both with emtricitabine/tenofovir 200/300 mg qd. Primary end point: change in triglyceride levels from baseline to week 12. Secondary end points: week 12 and week 48 changes in lipid parameters, insulin sensitivity, inflammatory/coagulation/bacterial translocation biomarkers, viral load, CD4(+) cell count, and week 48 changes in adipose tissue distribution and subjects' perceptions of body changes. In the DRV/r arm, 32/34 and 29/34 subjects completed weeks 12 and 48, respectively; in the ATV/r arm, 30/31 and 25/31 subjects completed weeks 12 and 48, respectively. Small changes in lipid parameters from baseline to weeks 12 and 48 were observed in both arms. Differences were noted between arms in mean changes in total cholesterol (DRV/r, 20.3 mg/dl; ATV/r, 4.6 mg/dl) and apolipoprotein A1 (DRV/r, 10.7 mg/dl; ATV/r, –0.7 mg/dl) at week 12. At week 48, no clinically relevant differences between arms were noted for changes in any lipid parameter, fasting glucose, or insulin sensitivity. Biomarkers generally decreased and efficacy parameters improved in both arms over 48 weeks. Changes in adipose tissue were small and comparable between arms. Subjects' perceptions of body changes generally improved in both study arms. This first pilot comparison in HIV-1-infected subjects suggests that DRV/r has a metabolic profile similar to ATV/r over 48 weeks of treatment. Further randomized studies are warranted
Macroscopic brain architecture changes and white matter pathology in acromegaly: a clinicoradiological study
Although long-term exposure of the brain to increased GH/IGF-1 likely influences cerebral functions, no in vivo studies have been directed towards changes of the brain structure in acromegaly. Here, we used high resolution magnetic resonance images to compare volumes of gray matter (GM), white matter (WM) and cerebrospinal fluid (CSF) of forty-four patients with acromegaly to an age and gender matched, healthy control group (n = 44). In addition, white matter lesions (WMLs) were quantified and graded. Patients exhibited larger GM (+3.7% compared with controls, P = 0.018) and WM volumes (+5.1%, P = 0.035) at the expense of CSF. Differences of WML counts between patients and controls were subtle, however, showing more patients in the 21–40 lesions category (P = 0.044). In conclusion, this MRI study provides first evidence that acromegalic patients exhibit disturbances of the macroscopic brain tissue architecture. Furthermore, acromegalic patients may have an increased risk of neurovascular pathology, likely due to secondary metabolic and vascular comorbidities
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