78 research outputs found
The cranking formula and the spurious behaviour of the mass parameters
We discuss some aspects of the approach of the mass parameters by means of
the simple cranking model. In particular, it is well known that the numerical
application of this formula is often subject to ambiguities or contradictions.
It is found that these problems are induced by the presence of two derivatives
in the formula. To overcome these problems, we state a useful ansatz and we
develop a number of simple arguments which tend to justify the removal of these
terms. As soon as this is done, the formula becomes simpler and easier to
interpret. In this respect, it is shown how the shell effects affect the mass
parameters. A number of numerical tests help us in our conclusions.Comment: version 3 corrigendum of the ansatz of section V, corrigendum of the
legend of Fig3. Submission = text file + 5 figure
Single particle calculations for a Woods-Saxon potential with triaxial deformations, and large Cartesian oscillator basis
We present a computer program which solves the Schrodinger equation of the
stationary states for an average nuclear potential of Woods-Saxon type. In this
work, we take specifically into account triaxial (i.e. ellipsoidal) nuclear
surfaces. The deformation is specified by the usual Bohr parameters. The
calculations are carried out in two stages. In the first, one calculates the
representative matrix of the Hamiltonian in the cartesian oscillator basis. In
the second stage one diagonalizes this matrix with the help of subroutines of
the EISPACK library. If it is wished, one can calculate all eigenvalues, or
only the part of the eigenvalues that are contained in a fixed interval defined
in advance. In this latter case the eigenvectors are given conjointly. The
program is very rapid, and the run-time is mainly used for the diagonalization.
Thus, it is possible to use a significant number of the basis states in order
to insure a best convergence of the results.Comment: no figures, but tbles in separate pdf file
Low-lying quadrupole collective states of the light and medium Xenon isotopes
Collective low lying levels of light and medium Xenon isotopes are deduced
from the Generalized Bohr Hamiltonian (GBH). The microscopic seven functions
entering into the GBH are built from a deformed mean field of the Woods-Saxon
type. Theoretical spectra are found to be close to the ones of the experimental
data taking into account that the calculations are completely microscopic, that
is to say, without any fitting of parameters.Comment: 8 pages, 4 figures, 1 tabl
Connection between the "Strutinsky level density" and the semiclassical level density (published version)
We establish an analytical link between the level density obtained by means
of the Strutinsky averaging method, and the semiclassical level density. This
link occurs only in the so-called "asymptotic limit". It turns out that the
Strutinsky method amounts to an approximation to the semiclassical method. This
approximation contains an unavoidable remainder which constitutes an intrinsic
noise in comparison to the semiclassical method. Thus, the "old" problem of the
dependency of the Strutinsky procedure on the two free smoothing parameters of
the averaging is intimately connected to this noise. On the other hand, we
demonstrate that the noise of the method is small in the average density of
states and in the average energy, whereas it might be non-negligible in the
shell correction itself. In order to improve this method, we give a "rule"
which consists simply of minimizing the relative error made on the average
energy.Comment: 6 figure
The unfinished agenda of communicable diseases among children and adolescents before the COVID-19 pandemic, 1990-2019: a systematic analysis of the Global Burden of Disease Study 2019
BACKGROUND: Communicable disease control has long been a focus of global health policy. There have been substantial reductions in the burden and mortality of communicable diseases among children younger than 5 years, but we know less about this burden in older children and adolescents, and it is unclear whether current programmes and policies remain aligned with targets for intervention. This knowledge is especially important for policy and programmes in the context of the COVID-19 pandemic. We aimed to use the Global Burden of Disease (GBD) Study 2019 to systematically characterise the burden of communicable diseases across childhood and adolescence. METHODS: In this systematic analysis of the GBD study from 1990 to 2019, all communicable diseases and their manifestations as modelled within GBD 2019 were included, categorised as 16 subgroups of common diseases or presentations. Data were reported for absolute count, prevalence, and incidence across measures of cause-specific mortality (deaths and years of life lost), disability (years lived with disability [YLDs]), and disease burden (disability-adjusted life-years [DALYs]) for children and adolescents aged 0-24 years. Data were reported across the Socio-demographic Index (SDI) and across time (1990-2019), and for 204 countries and territories. For HIV, we reported the mortality-to-incidence ratio (MIR) as a measure of health system performance. FINDINGS: In 2019, there were 3·0 million deaths and 30·0 million years of healthy life lost to disability (as measured by YLDs), corresponding to 288·4 million DALYs from communicable diseases among children and adolescents globally (57·3% of total communicable disease burden across all ages). Over time, there has been a shift in communicable disease burden from young children to older children and adolescents (largely driven by the considerable reductions in children younger than 5 years and slower progress elsewhere), although children younger than 5 years still accounted for most of the communicable disease burden in 2019. Disease burden and mortality were predominantly in low-SDI settings, with high and high-middle SDI settings also having an appreciable burden of communicable disease morbidity (4·0 million YLDs in 2019 alone). Three cause groups (enteric infections, lower-respiratory-tract infections, and malaria) accounted for 59·8% of the global communicable disease burden in children and adolescents, with tuberculosis and HIV both emerging as important causes during adolescence. HIV was the only cause for which disease burden increased over time, particularly in children and adolescents older than 5 years, and especially in females. Excess MIRs for HIV were observed for males aged 15-19 years in low-SDI settings. INTERPRETATION: Our analysis supports continued policy focus on enteric infections and lower-respiratory-tract infections, with orientation to children younger than 5 years in settings of low socioeconomic development. However, efforts should also be targeted to other conditions, particularly HIV, given its increased burden in older children and adolescents. Older children and adolescents also experience a large burden of communicable disease, further highlighting the need for efforts to extend beyond the first 5 years of life. Our analysis also identified substantial morbidity caused by communicable diseases affecting child and adolescent health across the world. FUNDING: The Australian National Health and Medical Research Council Centre for Research Excellence for Driving Investment in Global Adolescent Health and the Bill & Melinda Gates Foundation
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