31 research outputs found

    Estimation of technical efficiency in Greek livestock farms

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    In this present paper we use a panel data set during the period 1989-1992 to explore the distribution of productive efficiency among small sheep-breeding farmers operating in Greece. The results show that the average technical efficiency of the stock farmers was quite low (73.80%) and suggest the need for an advanced development strategy to improve their economic performance. Finally, the farmer's age and formal education, the credit access, the lack of successors and the farm's location are important factors explaining efficiency variation among farmers.L'efficacité technique des exploitations d'élevage en Grèce. Cette étude traite du rendement technique des exploitations d'élevage en Grèce en 1989-1992, afin d'évaluer l'éventuelle croissance ou diminution du cheptel en termes de productivité. Nous utilisons une enquête effectuée de 1989 à 1992 sur la répartition des gains de productivité dans les petites exploitations d'élevage en Grèce. Selon les résultats, le rendement technique moyen de ces exploitations est assez bas (75,80%) ; d'où la nécessité de mettre en place une stratégie de développement dynamique afin d'améliorer les résultats économiques. En fin de compte, l'âge de l'exploitant, le niveau de formation, l'accession au crédit, l'absence de successeurs ainsi que la localisation de l'exploitation sont autant de facteurs pouvant jouer sur les variations de rendement entre exploitations.Andreakos Ioannis, Tzouvelekas Vangelis, Mattas Konstantinos, Papanagiotou Evangelos. Estimation of technical efficiency in Greek livestock farms. In: Cahiers d'Economie et sociologie rurales, N°42-43, 1er et 2e trimestres 1997. économie du développement. Education ; pauvreté ; commerce international. pp. 93-107

    Direct Quantitation of Phytocannabinoids by One-Dimensional 1H qNMR and Two-Dimensional 1H-1H COSY qNMR in Complex Natural Mixtures

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    The widespread use of phytocannabinoids or cannabis extracts as ingredients in numerous types of products, in combination with the legal restrictions on THC content, has created a need for the development of new, rapid, and universal analytical methods for their quantitation that ideally could be applied without separation and standards. Based on previously described qNMR studies, we developed an expanded 1H qNMR method and a novel 2D-COSY qNMR method for the rapid quantitation of ten major phytocannabinoids in cannabis plant extracts and cannabis-based products. The 1H qNMR method was successfully developed for the quantitation of cannabidiol (CBD), cannabidiolic acid (CBDA), cannabinol (CBN), cannabichromene (CBC), cannabichromenic acid (CBCA), cannabigerol (CBG), cannabigerolic acid (CBGA), Δ9-tetrahydrocannabinol (Δ9-THC), Δ9-tetrahydrocannabinolic acid (Δ9-THCA), Δ8-tetrahydrocannabinol (Δ8-THC), cannabielsoin (CBE), and cannabidivarin (CBDV). Moreover, cannabidivarinic acid (CBDVA) and Δ9-tetrahydrocannabivarinic acid (Δ9-THCVA) can be distinguished from CBDA and Δ9-THCA respectively, while cannabigerovarin (CBGV) and Δ8-tetrahydrocannabivarin (Δ8-THCV) present the same 1H-spectra as CBG and Δ8-THC, respectively. The COSY qNMR method was applied for the quantitation of CBD, CBDA, CBN, CBG/CBGA, and THC/THCA. The two methods were applied for the analysis of hemp plants; cannabis extracts; edible cannabis medium-chain triglycerides (MCT); and hemp seed oils and cosmetic products with cannabinoids. The 1H-NMR method does not require the use of reference compounds, and it requires only a short time for analysis. However, complex extracts in 1H-NMR may have a lot of signals, and quantitation with this method is often hampered by peak overlap, with 2D NMR providing a solution to this obstacle. The most important advantage of the COSY NMR quantitation method was the determination of the legality of cannabis plants, extracts, and edible oils based on their THC/THCA content, particularly in the cases of some samples for which the determination of THC/THCA content by 1H qNMR was not feasible

    Clinical implications of chromosomal abnormalities in multiple myeloma

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    The adverse prognostic role of cytogenetic abnormalities has recently been established in plasma cell dyscrasias. Modern techniques such as fluorescence in situ hybridization and comparative genomic hybridization have revealed a higher incidence of cytogenetic abnormalities in patients with multiple myeloma (MM) compared to conventional cytogenetics. Hypodiploidy and chromosome 13 abnormalities are found in more than 50% of myeloma patients, representing well known factors with adverse prognosis. Rearrangements involving the switch regions of immunoglobulin heavy chain (IgH) gene at 14q32 with various partner genes represent the most common structural abnormalities, having an incidence of 70% in MM. Structural abnormalities of chromosomes 17 and 8 involving the p53 and c-myc genes are considered to be less frequent events, but carry a poor prognosis. New therapeutic approaches such as non-myeloablative allotransplantation and modern therapeutic agents (thalidomide, lenalidomide, and bortezomib) and their combinations give promise for an improved therapeutic management of patients with MM. The detection of t(4; 14), t(14; 16), deletion of chromosome 13 on metaphase analysis, or deletion of p53 by FISH will define high-risk prognostic groups that are not generally controlled with high-dose melphalan and autologous stem cell transplantation (ASCT), and should therefore be treated with more investigational therapies. Alternatively, eligible patients who do not have these poor risk factors are more likely to benefit from a high-dose, melphalan-based, regimen followed by ASCT

    Biotechnological Approaches on Two High CBD and CBG Cannabis sativa L. (Cannabaceae) Varieties: In Vitro Regeneration and Phytochemical Consistency Evaluation of Micropropagated Plants Using Quantitative 1H-NMR

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    High cannabidiol (CBD) and cannabigerol (CBG) varieties of Cannabis sativa L., a species with medicinal properties, were regenerated in vitro. Explants of nodal segments including healthy axillary bud, after sterilization, were placed in Murashige-Skoog (MS) culture medium. The shoots formed after 30 days were subcultured in full- or half-strength MS medium supplemented with several concentrations of 6-benzyl-amino-purine (BA) or thidiazuron (TDZ). The highest average number and length of shoots was achieved when both full and half-strength MS media were supplemented with 4.0 μM BA. The presence of 4.0 μM TDZ showed also comparable results. BA and TDZ at concentrations of 4.0, 8.0 μM and 2.0, 4.0 μM respectively, displayed the maximum shooting frequency. The new shoots were transferred on the same media and were either self-rooted or after being enhanced with different concentrations of indole-3-butyric acid (IBA) or α-naphthalene acetic acid (NAA). Presence of 2.0 or 4.0 μM IBA or 4.0 μM NAA resulted to the optimum rooting rates. The maximum average number and length of roots per shoot was observed when the culture media was supplemented with 4.0 μM IBA or NAA. Approximately 92% of the plantlets were successfully established and acclimatized in field. The consistency of the chemical profile of the acclimatized in vitro propagated clones was assessed using quantitative 1H-NMR high throughput screening. In each variety, analysis of the micropropagated plant in comparison with the mother plant showed no statistically significant differences (p ≤ 0.05) in CBD+ cannabidiolic acid (CBDA) and CBG+ cannabigerolic acid (CBGA) content respectively, thus indicating stability of their chemical profile

    Estimating the Energy Savings of Energy Efficiency Actions with Ensemble Machine Learning Models

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    Energy efficiency financing is considered among the top priorities in the energy sector among several stakeholders. In this context, accurately estimating the energy savings achieved by energy efficiency actions before being approved and implemented is of major importance to ensure the optimal allocation of the available financial resources. This study aims to provide a machine-learningbased methodological framework for a priori predicting the energy savings of energy efficiency renovation actions. The proposed solution consists of three tree-based algorithms that exploit bagging and boosting as well as an additional ensembling level that further mitigates prediction uncertainty. The proposed models are empirically evaluated using a database of various, diverse energy efficiency renovation investments. Results indicate that the ensemble model outperforms the three individual models in terms of forecasting accuracy. Also, the generated predictions are relatively accurate for all the examined project categories, a finding that supports the robustness of the proposed approach

    A Multi-Criteria Approach for Optimizing the Placement of Electric Vehicle Charging Stations in Highways

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    The electric vehicle (EV) industry has made significant progress but, in many markets, there are still barriers holding back its advancement. A key issue is the anxiety caused to the drivers by the limited range of current EV models and the inadequate access to charging stations in long-distance trips, as is the case on highways. We propose an intuitive multi-criteria approach that optimally places EV charging stations on highways that (partially) lack such points. The approach, which is applied in an iterative fashion to dynamically evaluate the alternatives, considers a set of practical criteria related to the traffic intensity and the relative location of the charging stations with interchanges, major cities, and existing stations, thus supporting decisions in a pragmatic way. The optimal locations are determined by taking into consideration constraints about the EV driving range and installation preferences to improve the operation of the highway while ensuring reasonable cost of investment. The proposed approach is showcased in the Egnatia Motorway, the longest highway in Greece that runs a total of 670 km but currently involves a single EV charging point. Our findings illustrate the utility of the proposed approach and highlight its merits as a decision-support tool
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