281 research outputs found

    ADAPTATION OF MEDITERRANEAN CROPS TO WATER PRESSURE IN THE EBRO BASIN: A WATER EFFICIENCY INDEX

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    In this paper, we assess the output-oriented technical efficiency of agricultural production functions in order to compare, over time, economic and environmental production processes in the different regions of the Spanish Ebro basin, in a climate change context. The measurement of technical efficiency in agriculture can provide useful information about the competitiveness of farms and their potential to increase its productivity moreover can help in the crops adaptation to water pressure by improving the management of scarce resources. Here, we generate an agricultural water efficiency index to evaluate the adaptation of some Mediterranean crops to the water pressures in this area. We estimate frontier production functions and technical efficiency measures, using panel data models. This will allow us to observe changes in production due to individual specific effects and those that are time specific. To characterize our model, we use historical data, about crop yields, water requirements and climate as well as socio-economic and geographical aspects of the most representative crops in the provinces of the Ebro basin during 1976-2007. Then we generate a ranking of the most efficient crops across geographical areas, given their water use and other inputs, to evaluate policy scenarios with adjustments in water supply.water efficiency index in agriculture, Ebro basin, climate change adaptation, Crop Production/Industries, Resource /Energy Economics and Policy,

    Fragility of the antichiral edge states under disorder

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    Chiral edge states are the fingerprint of the bulk-edge correspondence in a Chern insulator. Co-propagating edge modes, known as antichiral edge states, have been predicted to occur in the so-called modified Haldane model describing a two-dimensional semi-metal with broken time reversal symmetry. These counterintuitive edge modes are argued to be immune to backscattering and extremely robust against disorder. Here, we investigate the robustness of the antichiral edge states in the presence of Anderson disorder. By analysing different localization parameters, we show that, contrary to the general belief, these edge modes are fragile against disorder, and can be easily localized. Our work provides insights to improve the transport efficiency in the burgeoning fields of antichiral topological photonics and acoustics.Comment: 9 pages, 6 figure

    Twisted bilayer graphene reveals its flat bands under spin pumping

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    The salient property of the electronic band structure of twisted bilayer graphene (TBG), at the so-called magic angle (MA), is the emergence of flat bands around the charge neutrality point. These bands are associated with the observed superconducting phases and the correlated insulating states. Scanning tunneling microscopy combined with angle resolved photoemission spectroscopy are usually used to visualize the flatness of the band structure of TBG at the MA. Here, we theoretically argue that spin pumping (SP) provides a direct probe of the flat bands of TBG and an accurate determination of the MA. We consider a junction separating a ferromagnetic insulator and a heterostructure of TBG adjacent to a monolayer of a transition metal dichalcogenide. We show that the Gilbert damping of the ferromagnetic resonance experiment, through this junction, depends on the twist angle of TBG, and exhibits a sharp drop at the MA. We discuss the experimental realization of our results which open the way to a twist switchable spintronics in twisted van der Waals heterostructures.Comment: 8 pages + supplemental material (revised version

    Crop yields response to water pressures in the Ebro basin in Spain: risk and water policy implications

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    he increasing pressure on water systems in the Mediterranean enhances existing water conflicts and threatens water supply for agriculture. In this context, one of the main priorities for agricultural research and public policy is the adaptation of crop yields to water pressures. This paper focuses on the evaluation of hydrological risk and water policy implications for food production. Our methodological approach includes four steps. For the first step, we estimate the impacts of rainfall and irrigation water on crop yields. However, this study is not limited to general crop production functions since it also considers the linkages between those economic and biophysical aspects which may have an important effect on crop productivity. We use statistical models of yield response to address how hydrological variables affect the yield of the main Mediterranean crops in the Ebro river basin. In the second step, this study takes into consideration the effects of those interactions and analyzes gross value added sensitivity to crop production changes. We then use Montecarlo simulations to characterize crop yield risk to water variability. Finally we evaluate some policy scenarios with irrigated area adjustments that could cope in a context of increased water scarcity. A substantial decrease in irrigated land, of up to 30% of total, results in only moderate losses of crop productivity. The response is crop and region specific and may serve to prioritise adaptation strategies

    Risk of water scarcity and water policy implications for crop production in the Ebro basin in Spain

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    The increasing pressure on water systems in the Mediterranean enhances existing water conflicts and threatens water supply for agriculture. In this context, one of the main priorities for agricultural research and public policy is the adaptation of crop yields to water pressures. This paper focuses on the evaluation of hydrological risk and water policy implications for food production. Our methodological approach includes four steps. For the first step, we estimate the impacts of rainfall and irrigation water on crop yields. However, this study is not limited to general crop production functions since it also considers the linkages between those economic and biophysical aspects which may have an important effect on crop productivity. We use statistical models of yield response to address how hydrological variables affect the yield of the main Mediterranean crops in the Ebro River Basin. In the second step, this study takes into consideration the effects of those interactions and analyzes gross value added sensitivity to crop production changes. We then use Montecarlo simulations to characterize crop yield risk to water variability. Finally we evaluate some policy scenarios with irrigated area adjustments that could cope in a context of increased water scarcity. A substantial decrease in irrigated land, of up to 30% of total, results in only moderate losses of crop productivity. The response is crop and region specific and may serve to prioritise adaptation strategies

    Breast diseases in women over the age of 65 in Monastir, Tunisia

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    As life expectancy is on the rise, it is predicted that a growing number of people will live beyond the age of 65 and therefore a higher number of elderly women will have breast diseases requiring significant health care and services. This study is aimed at investigating the characteristics, the treatment and outcomes of women older than 65 years old treated for breast diseases at our institution. This was a retrospective study covering the period from January 2003 to December 2011. It involved 92 patients aged over 65 and treated for breast disease in the Maternity Center of Monastir, Tunisia. The data included characteristics of patients and tumors, treatment and outcomes that were obtained through data extraction sheets. We reported a study of 92 women over the age of 65 of whom 77 women had malignant breast disease (83.6%) and 15 benign breast diseases (16.4%). Breast cancer was discovered at a mean age of 72.5 ± 6.6 years. Distant metastases were found in 5.3% of cases and infiltrative ductal carcinoma was detected in 85.7% of patients. Hormonal receptors were positive for estrogens in 64.7% of cases. Surgical treatment was performed in 73 patients and adjuvant treatment was prescribed for 67 women (86%). The complication rate was 16.6% among the 73 patients who underwent surgery. Benign breast diseases represented 16.3% of the mammary pathologies. Abscesses and fibrocystic mastopathy were the most frequent histological diagnoses. Despite great interest in geriatric gynecological pathology worldwide, many questions related to how optimally treat this patient population remain unanswered. In this study, a surgical treatment was performed in 94.8% of breast cancer patients and the complication rate was 16.6%

    SLEEP QUALITY OF OBESE WORKERS OF A TEACHING HOSPITAL: ACUPUNCTURE AS A COMPLEMENTARY THERAPY

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    The objective of this study was to verify the effect of acupuncture on the sleep quality of obese workers in a teaching hospital. Data were collected from July to October 2009, focusing on 37 workers who attended eight weekly acupuncture sessions. The Pittsburgh Sleep Quality Index was used to assess their sleep quality before and after the intervention. Results show that before the intervention, five (13.5%) people experienced good quality of sleep whereas at the end of the study 14 (37.8%) showed this condition. Statistic significance (p=0.0001) was found in comparing the mean scores obtained before and after acupuncture. Acupuncture had effects on the quality of sleep in the studied sample, presenting itself as a complementary technique for treating sleep disorders and consequently improving the quality of life in this population
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