70 research outputs found
Second T = 3/2 state in B and the isobaric multiplet mass equation
Recent high-precision mass measurements and shell model calculations~[Phys.
Rev. Lett. {\bf 108}, 212501 (2012)] have challenged a longstanding explanation
for the requirement of a cubic isobaric multiplet mass equation for the lowest
isospin quartet. The conclusions relied upon the choice of the
excitation energy for the second state in B, which had two
conflicting measurements prior to this work. We remeasured the energy of the
state using the reaction and significantly disagree
with the most recent measurement. Our result supports the contention that
continuum coupling in the most proton-rich member of the quartet is not the
predominant reason for the large cubic term required for nuclei
Isoscalar giant monopole strength in Ni, Zr, Sn and Pb
Inelastic -particle scattering at energies of a few hundred MeV and
very-forward scattering angles including has been established as a
tool for the study of the isoscalar giant monopole (IS0) strength distributions
in nuclei. An independent investigation of the IS0 strength in nuclei across a
wide mass range was performed using the facility at iThemba
Laboratory for Accelerator Based Sciences (iThemba LABS), South Africa, to
understand differences observed between IS0 strength distributions in previous
experiments performed at the Texas A\&M University (TAMU) Cyclotron Institute,
USA and the Research Center for Nuclear Physics (RCNP), Japan. The isoscalar
giant monopole resonance (ISGMR) was excited in Ni, Zr,
Sn and Pb using -particle inelastic scattering with
MeV beam and scattering angles
and . The K magnetic spectrometer at iThemba LABS was used to
detect and momentum analyze the inelastically scattered particles. The
IS0 strength distributions in the nuclei studied were deduced with the
difference-of-spectra (DoS) technique including a correction factor for the
data based on the decomposition of cross sections in previous
experiments. IS0 strength distributions for Ni, Zr, Sn
and Pb are extracted in the excitation-energy region MeV.Using correction factors extracted from the RCNP experiments, there is
a fair agreement with their published IS0 results. Good agreement for IS0
strength in Ni is also obtained with correction factors deduced from the
TAMU results, while marked differences are found for Zr and Pb.Comment: 12 pages, 10 figures, regular article submitted to PR
Fine structure of the isoscalar giant monopole resonance in Ni, Zr, Sn and Pb
Over the past two decades high energy-resolution inelastic proton scattering
studies were used to gain an understanding of the origin of fine structure
observed in the isoscalar giant quadrupole resonance (ISGQR) and the isovector
giant dipole resonance (IVGDR). Recently, the isoscalar giant monopole
resonance (ISGMR) in Ni, Zr, Sn and Pb was
studied at the iThemba Laboratory for Accelerator Based Sciences (iThemba LABS)
by means of inelastic -particle scattering at very forward scattering
angles (including ). The good energy resolution of the measurement
revealed significant fine structure of the ISGMR.~To extract scales by means of
wavelet analysis characterizing the observed fine structure of the ISGMR in
order to investigate the role of different mechanisms contributing to its decay
width. Characteristic energy scales are extracted from the fine structure using
continuous wavelet transforms. The experimental energy scales are compared to
different theoretical approaches performed in the framework of quasiparticle
random phase approximation (QRPA) and beyond-QRPA including complex
configurations using both non-relativistic and relativistic density functional
theory. All models highlight the role of Landau fragmentation for the damping
of the ISGMR especially in the medium-mass region. Models which include the
coupling between one particle-one hole (1p-1h) and two particle-two hole
(2p-2h) configurations modify the strength distributions and wavelet scales
indicating the importance of the spreading width. The effect becomes more
pronounced with increasing mass number. Wavelet scales remain a sensitive
measure of the interplay between Landau fragmentation and the spreading width
in the description of the fine structure of giant resonances.Comment: 13 pages,7 figures, regular articl
Sulphadoxine/pyrimethamine versus amodiaquine for treating uncomplicated childhood malaria in Gabon: A randomized trial to guide national policy
<p>Abstract</p> <p>Background</p> <p>In Gabon, following the adoption of amodiaquine/artesunate combination (AQ/AS) as first-line treatment of malaria and of sulphadoxine/pyrimethamine (SP) for preventive intermittent treatment of pregnant women, a clinical trial of SP versus AQ was conducted in a sub-urban area. This is the first study carried out in Gabon following the WHO guidelines.</p> <p>Methods</p> <p>A random comparison of the efficacy of AQ (10 mg/kg/day × 3 d) and a single dose of SP (25 mg/kg of sulphadoxine/1.25 mg/kg of pyrimethamine) was performed in children under five years of age, with uncomplicated falciparum malaria, using the 28-day WHO therapeutic efficacy test. In addition, molecular genotyping was performed to distinguish recrudescence from reinfection and to determine the frequency of the <it>dhps </it>K540E mutation, as a molecular marker to predict SP-treatment failure.</p> <p>Results</p> <p>The day-28 PCR-adjusted treatment failures for SP and AQ were 11.6% (8/69; 95% IC: 5.5–22.1) and 28.2% (20/71; 95% CI: 17.7–38.7), respectively This indicated that SP was significantly superior to AQ (<it>P </it>= 0.019) in the treatment of uncomplicated childhood malaria and for preventing recurrent infections. Both treatments were safe and well-tolerated, with no serious adverse reactions recorded. The <it>dhps </it>K540E mutation was not found among the 76 parasite isolates tested.</p> <p>Conclusion</p> <p>The level of AQ-resistance observed in the present study may compromise efficacy and duration of use of the AQ/AS combination, the new first-line malaria treatment. Gabonese policy-makers need to plan country-wide and close surveillance of AQ/AS efficacy to determine whether, and for how long, these new recommendations for the treatment of uncomplicated malaria remain valid.</p
Evidence of decline of malaria in the general hospital of Libreville, Gabon from 2000 to 2008
BACKGROUND: Substantial decline in malaria transmission, morbidity and mortality has been reported in several countries where new malaria control strategies have been implemented. In Gabon, the national malaria policy changed in 2003, according to the WHO recommendations. The trend in malaria morbidity was evaluated among febrile children before and after their implementation in Libreville, the capital city of Gabon.
METHODS: From August 2000 to December 2008, febrile paediatric outpatients and inpatients, under 11 years of age, were screened for malaria by microscopic examination at the Malaria Clinical Research Unit (MCRU) located in the largest public hospital in Gabon. Climatic data were also collected.
RESULTS: In total, 28,092 febrile children were examined; those under five years always represented more than 70%. The proportion of malaria-positive slides was 45% in 2000, and declined to 15% in 2008. The median age of children with a positive blood smear increased from 24(15-48) to 41(21-72) months over the study period (p < 0.01). Rainfall patterns had no impact on the decline observed throughout the study period.
CONCLUSION: The decrease of malaria prevalence among febrile children during the last nine years is observed following the introduction of new strategies of malaria cases management, and may announce epidemiological changes. Moreover, preventive measures must be extended to children older than five years
Awareness and knowledge regarding of cervical cancer, Pap smear screening and human papillomavirus infection in Gabonese women
Population and fertility by age and sex for 195 countries and territories, 1950–2017: a systematic analysis for the Global Burden of Disease Study 2017
Background:
Population estimates underpin demographic and epidemiological research and are used to track progress on numerous international indicators of health and development. To date, internationally available estimates of population and fertility, although useful, have not been produced with transparent and replicable methods and do not use standardised estimates of mortality. We present single-calendar year and single-year of age estimates of fertility and population by sex with standardised and replicable methods.
Methods:
We estimated population in 195 locations by single year of age and single calendar year from 1950 to 2017 with standardised and replicable methods. We based the estimates on the demographic balancing equation, with inputs of fertility, mortality, population, and migration data. Fertility data came from 7817 location-years of vital registration data, 429 surveys reporting complete birth histories, and 977 surveys and censuses reporting summary birth histories. We estimated age-specific fertility rates (ASFRs; the annual number of livebirths to women of a specified age group per 1000 women in that age group) by use of spatiotemporal Gaussian process regression and used the ASFRs to estimate total fertility rates (TFRs; the average number of children a woman would bear if she survived through the end of the reproductive age span [age 10–54 years] and experienced at each age a particular set of ASFRs observed in the year of interest). Because of sparse data, fertility at ages 10–14 years and 50–54 years was estimated from data on fertility in women aged 15–19 years and 45–49 years, through use of linear regression. Age-specific mortality data came from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017 estimates. Data on population came from 1257 censuses and 761 population registry location-years and were adjusted for underenumeration and age misreporting with standard demographic methods. Migration was estimated with the GBD Bayesian demographic balancing model, after incorporating information about refugee migration into the model prior. Final population estimates used the cohort-component method of population projection, with inputs of fertility, mortality, and migration data. Population uncertainty was estimated by use of out-of-sample predictive validity testing. With these data, we estimated the trends in population by age and sex and in fertility by age between 1950 and 2017 in 195 countries and territories.
Findings:
From 1950 to 2017, TFRs decreased by 49·4% (95% uncertainty interval [UI] 46·4–52·0). The TFR decreased from 4·7 livebirths (4·5–4·9) to 2·4 livebirths (2·2–2·5), and the ASFR of mothers aged 10–19 years decreased from 37 livebirths (34–40) to 22 livebirths (19–24) per 1000 women. Despite reductions in the TFR, the global population has been increasing by an average of 83·8 million people per year since 1985. The global population increased by 197·2% (193·3–200·8) since 1950, from 2·6 billion (2·5–2·6) to 7·6 billion (7·4–7·9) people in 2017; much of this increase was in the proportion of the global population in south Asia and sub-Saharan Africa. The global annual rate of population growth increased between 1950 and 1964, when it peaked at 2·0%; this rate then remained nearly constant until 1970 and then decreased to 1·1% in 2017. Population growth rates in the southeast Asia, east Asia, and Oceania GBD super-region decreased from 2·5% in 1963 to 0·7% in 2017, whereas in sub-Saharan Africa, population growth rates were almost at the highest reported levels ever in 2017, when they were at 2·7%. The global average age increased from 26·6 years in 1950 to 32·1 years in 2017, and the proportion of the population that is of working age (age 15–64 years) increased from 59·9% to 65·3%. At the national level, the TFR decreased in all countries and territories between 1950 and 2017; in 2017, TFRs ranged from a low of 1·0 livebirths (95% UI 0·9–1·2) in Cyprus to a high of 7·1 livebirths (6·8–7·4) in Niger. The TFR under age 25 years (TFU25; number of livebirths expected by age 25 years for a hypothetical woman who survived the age group and was exposed to current ASFRs) in 2017 ranged from 0·08 livebirths (0·07–0·09) in South Korea to 2·4 livebirths (2·2–2·6) in Niger, and the TFR over age 30 years (TFO30; number of livebirths expected for a hypothetical woman ageing from 30 to 54 years who survived the age group and was exposed to current ASFRs) ranged from a low of 0·3 livebirths (0·3–0·4) in Puerto Rico to a high of 3·1 livebirths (3·0–3·2) in Niger. TFO30 was higher than TFU25 in 145 countries and territories in 2017. 33 countries had a negative population growth rate from 2010 to 2017, most of which were located in central, eastern, and western Europe, whereas population growth rates of more than 2·0% were seen in 33 of 46 countries in sub-Saharan Africa. In 2017, less than 65% of the national population was of working age in 12 of 34 high-income countries, and less than 50% of the national population was of working age in Mali, Chad, and Niger.
Interpretation:
Population trends create demographic dividends and headwinds (ie, economic benefits and detriments) that affect national economies and determine national planning needs. Although TFRs are decreasing, the global population continues to grow as mortality declines, with diverse patterns at the national level and across age groups. To our knowledge, this is the first study to provide transparent and replicable estimates of population and fertility, which can be used to inform decision making and to monitor progress
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