537 research outputs found
Mass number and excitation energy dependence of the parameter of the spin cut-off factor in the formation of an isomeric pair
The parameter of the spin distribution of the
level density was determined for 61 nuclei covering the mass range of 44 to
200. The experimental isomeric cross-section ratios for 25 isomeric pairs were
compared with the model calculation to find the best fit to the experimental
data. The model calculations were carried out with the TALYS code using the
BSFG model for the level density. The reduced values were calculated
to describe the deviation of the experimental data from the model calculation.
An was introduced calculating the value
from the low energy discrete levels of the nucleus. The values
seem to be independent of the mass number, their average value near to one. The
values also seem to be independent of the average excitation
energy in the continuum, indicating that is independent of the
excitation energy. The mass number and (N-Z) dependence of the values
were studied. The values for the nuclei with odd mass number show an
exponential decrease as a function of A or (N-Z). The values for the
odd-odd type of nuclei appear to be constant, near one, up to the mass number
110 or (N-Z) of 13. Above these values, the values show exponential
decrease. The values for even-even type nuclei decrease exponentially
up to A equal to 142 or (N-Z) equal to 20. The values are lower than those for
the nearby odd-odd type nuclei. The values increase for nuclei with A
between 142 and 156 and (N-Z) between 20 and 28, and they finally reach the
value of odd-odd type systematics.Comment: 67+3 pages, 52+2 figures. Calculations with EMPIRE have been added to
Section IV.
Development of Cyclotron Radionuclides for Medical Applications: From fundamental nuclear data to sophisticated production technology
Soon after the discovery of radioactivity it was shown that radionuclides can be used both for diagnostic and therapeutic studies, depending on the characteristic radiations emitted by them. By 1960ās the radionuclide production technology using nuclear reactors was well established. In early 1970ās a renaissance of the cyclotrons occurred because many of the neutron deficient radionuclides could only be produced using irradiations with charged particles, like protons, deuterons, Ī±-particles, etc. Initially, interest was directed towards radioactive gases for inhalation studies and other radionuclides for scintigraphy. Later, with the advent of emission tomography, i.e. Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET), the emphasis shifted to 123I and positron emitters [cf. 1ā3], and tremendous progress ensued. In order to keep abreast of the fast developments, a Symposium was organized at the Brookhaven National Laboratory (BNL), USA, in 1976, with the title āRadiopharmaceutical Chemistryā. This became a biennial event, with alternate meetings in North America and Europe. It included all aspects of radionuclide and radiopharmaceutical research. About a decade later, however, it was realized that for discussion of technical aspects, a separate forum would be more appropriate. A group of experts therefore convened the first Targetry Workshop in Heidelberg in 1985. Thereafter it was established as a recurring Workshop, with its scope enlargened to include also nuclear and radiochemical problems. Today, the major conference on Radiopharmaceutical Sciences and the specialist International Workshop on Target-ry and Target Chemistry are held in alternate years. The present Workshop is No. 15 in the series and it is being jointly held by the research groups in Dresden and Prague, both of which have a long tradition of cyclotron production of radionuclides. In this talk, some personal reminiscences and impressions of the historical de-velopments in the field over the last 40 years will be briefly described
GM crops and gender issues
Correspondence in the December issue by Jonathan Gressel not only states that gender issues in rural settings have not been adequately addressed with respect to weed control biotech but also asserts that such technology can increase the quality of life of rural women in developing countries. Improved weed control is a labor-saving technology that can result in less employment in a labor surplus rural economy. Often in rural areas, wage income is the main source of income and an important determinant of the quality of life, particularly where employment opportunities are generally limited. Apart from soil preparation, planting and weeding, harvesting is also 'femanual' work that can generate more employment if yields are higher. Biotech can enhance the quality of life of women but only if the technology is associated with overall generation of rural employment
Experimental studies and nuclear model calculations on (p,xn) and (p,pxn) reactions on 85Rb from their threshold up to 100 MeV
Excitation functions were measured by the stacked-foil technique for the reactions Rb-85(p, pxn)Rb-89m,Rb-g83,Rb-82m.81 from their thresholds up to 100MeV. Nuclear model calculations were performed using the code ALICE-IPPE both on (p, xn) reactions reported earlier and (p, pxn) reactions described here. The experimental excitation curves and the results of nuclear model calculations were found to be qualitatively in agreement. With the exception of the (p, n) reaction above 40MeV, the theory appears to reproduce all the experimental data within deviations of about 50%. The cross section ratios for the isomeric pairs Sr-85m,Sr-g and Rb-84m,Rb-g are discussed qualitatively in terms of the spins of the states involved and the increasing projectile energy
Supermarket purchase contributes to nutrition-related non-communicable diseases in urban Kenya
Background While undernutrition and related infectious diseases are still pervasive in many developing countries, the prevalence of non-communicable diseases (NCD), typically associated with high body mass index (BMI), is rapidly rising. The fast spread of supermarkets and related shifts in diets were identified as possible factors contributing to overweight and obesity in developing countries. Potential effects of supermarkets on peopleās health have not been analyzed up till now. Objective This study investigates the effects of purchasing food in supermarkets on peopleās BMI, as well as on health indicators such as fasting blood glucose (FBG), blood pressure (BP), and the metabolic syndrome. Design This study uses cross-section observational data from urban Kenya. Demographic, anthropometric, and bio-medical data were collected from 550 randomly selected adults. Purchasing food in supermarkets is defined as a binary variable that takes a value of one if any food was purchased in supermarkets during the last 30 days. In a robustness check, the share of food purchased in supermarkets is defined as a continuous variable. Instrumental variable regressions are applied to control for confounding factors and establish causality. Results Purchasing food in supermarkets contributes to higher BMI (+ 1.8 kg/m2 ) (P<0.01) and an increased probability (+ 20 percentage points) of being overweight or obese (P<0.01). Purchasing food in supermarkets also contributes to higher levels of FBG (+ 0.3 mmol/L) (P<0.01) and a higher likelihood (+ 16 percentage points) of suffering from pre-diabetes (P<0.01) and the metabolic syndrome (+ 7 percentage points) (P<0.01). Effects on BP could not be observed. Conclusions Supermarkets and their food sales strategies seem to have direct effects on peopleās health. In addition to increasing overweight and obesity, supermarkets contribute to nutrition-related NCDs. Effects of supermarkets on nutrition and health can mainly be ascribed to changes in the composition of peopleās food choices
Recommended from our members
Excitation functions and isomeric cross-section ratios of (d,xn) reactions on 86Sr
Excitation functions of the 86Sr(d,n)87m,87gY, 86Sr(d,2n)86m,86gY and 86Sr(d,3n)85m,85gY reactions on enriched 86Sr target were measured by the activation technique up to deuteron energies of 49 MeV. The isomeric cross-section ratios as a function of projectile energy were deduced from the measured data for 87mY, 87gY(cum), 86mY, 86gY(cum), 85mY and 85gY pairs for the same energy range. All measurements are reported for the first time. The experimental data were compared with the data from the TENDL library which is based on TALYS calculation with default parameters. No satisfactory agreement was observed. Nuclear model calculations were then performed using the codes TALYS and EMPIRE with some parameter adjustments, and compared with the experimental data. The quality of the agreement between experimental data and model calculations was numerically quantified. In general, the data as well as the isomeric cross-section ratios are partially reproduced by the model calculations, provided the input model parameters are properly chosen and the level structure of the product nucleus is thoughtfully considered
Options to Reform the European Union Legislation on GMOs: Scope and Definitions
We discuss options to reform the EU genetically modified organisms (GMO) regulatory framework, make risk assessment and decision-making more consistent with scientific principles, and lay the groundwork for international coherence. The first in a three-part series, this article focuses on reform options related to the scope of the legislation and the GMO definition
Sustainable food security in IndiaāDomestic production and macronutrient availability
<div><p>India has been perceived as a development enigma: Recent rates of economic growth have not been matched by similar rates in health and nutritional improvements. To meet the second Sustainable Development Goal (SDG2) of achieving zero hunger by 2030, India faces a substantial challenge in meeting basic nutritional needs in addition to addressing population, environmental and dietary pressures. Here we have mappedāfor the first timeāthe Indian food system from crop production to household-level availability across three key macronutrients categories of ācaloriesā, ādigestible proteinā and āfatā. To better understand the potential of reduced food chain losses and improved crop yields to close future food deficits, scenario analysis was conducted to 2030 and 2050. Under Indiaās current self-sufficiency model, our analysis indicates severe shortfalls in availability of all macronutrients across a large proportion (>60%) of the Indian population. The extent of projected shortfalls continues to grow such that, even in ambitious waste reduction and yield scenarios, enhanced domestic production alone will be inadequate in closing the nutrition supply gap. We suggest that to meet SDG2 India will need to take a combined approach of optimising domestic production and increasing its participation in global trade.</p></div
- ā¦