536 research outputs found

    Mass number and excitation energy dependence of the Θeff/Θrig\Theta_{eff}/\Theta_{rig} parameter of the spin cut-off factor in the formation of an isomeric pair

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    The Θeff/Θrig\Theta_{eff}/\Theta_{rig} 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 χ2\chi ^2 values were calculated to describe the deviation of the experimental data from the model calculation. An ηd\eta_d was introduced calculating the Θeff/Θrig\Theta_{eff}/\Theta_{rig} value from the low energy discrete levels of the nucleus. The η/ηd\eta /\eta_d values seem to be independent of the mass number, their average value near to one. The η/ηd\eta /\eta_d values also seem to be independent of the average excitation energy in the continuum, indicating that η\eta is independent of the excitation energy. The mass number and (N-Z) dependence of the η\eta values were studied. The η\eta values for the nuclei with odd mass number show an exponential decrease as a function of A or (N-Z). The η\eta 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 η\eta values show exponential decrease. The η\eta 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 η\eta 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

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    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 1960’s the radionuclide production technology using nuclear reactors was well established. In early 1970’s 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, α-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. 1–3], 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 “Radiopharmaceutical Chemistry”. 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

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    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

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    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

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    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 people’s health have not been analyzed up till now. Objective This study investigates the effects of purchasing food in supermarkets on people’s 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 people’s 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 people’s food choices

    Options to Reform the European Union Legislation on GMOs: Scope and Definitions

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    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 India—Domestic production and macronutrient availability

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    <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 mapped—for the first time—the Indian food system from crop production to household-level availability across three key macronutrients categories of ‘calories’, ‘digestible protein’ and ‘fat’. 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 India’s 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

    A Built-In Mechanism to Mitigate the Spread of Insect-Resistance and Herbicide-Tolerance Transgenes into Weedy Rice Populations

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    BACKGROUND: The major challenge of cultivating genetically modified (GM) rice (Oryza sativa) at the commercial scale is to prevent the spread of transgenes from GM cultivated rice to its coexisting weedy rice (O. sativa f. spontanea). The strategic development of GM rice with a built-in control mechanism can mitigate transgene spread in weedy rice populations. METHODOLOGY/PRINCIPAL FINDINGS: An RNAi cassette suppressing the expression of the bentazon detoxifying enzyme CYP81A6 was constructed into the T-DNA which contained two tightly linked transgenes expressing the Bt insecticidal protein Cry1Ab and the glyphosate tolerant 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), respectively. GM rice plants developed from this T-DNA were resistant to lepidopteran pests and tolerant to glyphosate, but sensitive to bentazon. The application of bentazon of 2000 mg/L at the rate of 40 mL/m(2), which is approximately the recommended dose for the field application to control common rice weeds, killed all F(2) plants containing the transgenes generated from the Crop-weed hybrids between a GM rice line (CGH-13) and two weedy rice strains (PI-63 and PI-1401). CONCLUSIONS/SIGNIFICANCE: Weedy rice plants containing transgenes from GM rice through gene flow can be selectively killed by the spray of bentazon when a non-GM rice variety is cultivated alternately in a few-year interval. The built-in control mechanism in combination of cropping management is likely to mitigate the spread of transgenes into weedy rice populations
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