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Ymittos Athens, Greece

The Agricultural University of Athens is the third oldest university in Greece. Since 1920, it has been making valuable contributions to Greek agricultural and economic development, by conducting basic and applied research in the agricultural science.The University is situated at the neighborhood of Votanikos, on a 25-hectare green campus that straddles both sides of the historic Iera Odos , close to the Acropolis, at the heart of the ancient Olive Grove. Its sixteen buildings comprise: auditoriums, 41 fully equipped laboratories, a modern library, computer rooms, extensive agricultural facilities , museums, student center, indoor gym, and sports fields. Wikipedia.

Valiantzas J.D.,Agricultural University of Athens
Journal of Irrigation and Drainage Engineering

In this paper, new algebraic expressions are derived for estimating reference evapotranspiration (ET0) from limited meteorological data. Reference evapotranspiration is commonly computed from readily available measured data at weather stations; e.g., solar radiation, RS (MJ/m2/d); relative humidity, RH (%); wind speed, u (m/s); and average temperature, T (°C). Recently, a simple algebraic formula, equivalent in accuracy to the Penman equation, was derived by Valiantzas for computing ET0 from readily available measured data. The derivation of the formula is based on simplifications made to the standardized form of the Penman equation. In a first place, an improved and more simplified form of Penman's equation is proposed, requiring a full set of data. The new full set of data formula is obtained by calibration using meteorological data obtained from the CLIMWAT global database. For many places where reliable wind speed data are not available, an expression is also suggested that does not require wind data. Further simplifications were applied in the proposed formula to derive the following new formula based on RS and T measurements alone: ET0 ≈ 0.0393RS √T+9.5-0.19R0.6 S φ0.15+0.0061(T + 20)(1.12T - Tmin - 2)0.7 where Tmin = minimum temperature; and φ (rad) = latitude of the station. The proposed formula, which requires limited data, can be also applied when taking the local long-term average wind speed value into account. Evaluation of the formulas and comparisons with other methods using daily meteorological data are given in the companion paper. © 2013 American Society of Civil Engineers. Source

Valiantzas J.D.,Agricultural University of Athens
Journal of Irrigation and Drainage Engineering

In the companion paper, a set of simplified formulas was derived to approximate the Penman equation for estimating reference evapotranspiration (ET0) from limited data. The first suggested formula is explicit for routinely measured data: air temperature, solar radiation, relative humidity, and wind velocity. Simplifications of this formula were made for places where wind speed and/or relative humidity data are not available. The performance of the new derived formulas was tested under various climatic conditions using highquality daily weather data from 17 agricultural weather stations across California obtained from the California Irrigation Management Information System (CIMIS) database. The daily CIMIS-Penman estimations, obtained by summing hourly computations over 24 h periods and by using the standardized FAO-56 Penman Monteith scheme applied on a daily basis, were used as the basis for comparisons at the 17 stations in California. The performance of the formula with a full set of data is excellent. The formula without wind data was compared with other common empirical methods (reduced-set FAO procedure not requiring wind data, Turk, and radiation-based Hargreaves), whereas the formula without wind and humidity data was compared with the radiation-based Hargreaves and the reduced-set FAO procedure that does not require wind and humidity. Comparisons of the methods indicated that the proposed formulas is a better option than the other empirical methods for estimating ET0 when wind and/or relative humidity data are missing. © 2013 American Society of Civil Engineers. Source

Politis I.,Agricultural University of Athens
Animal

Although vitamin E has been known as an essential nutrient for almost 80 years, we are far from a complete understanding of all the aspects related to bioavailability and its effects on health and milk quality in dairy cows. Vitamin E is a generic descriptor for two families of lipid-soluble compounds, the tocopherols and the tocotrienols, of which α-tocopherol has the highest biological activity. Commercially available α-tocopherol supplements for dairy cows contain either the natural RRR form or the synthetic (all-rac) form, which contains all the eight possible stereoisomers (four possessing the 2R and four possessing the 2S configuration) in equimolar amounts. Recent data clearly suggest that an almost complete discrimination against the 2S isomers occurs in dairy cows. Thus, 1 g of the all-rac form is essentially equivalent to 0.5 g of the RRR form. With respect to the effect of vitamin E supplementation of dairy cows on health and milk quality, the majority of published studies suggests that vitamin E supplementation at the level 1000 to 4000 IU/cow per day during the dry period reduces both the frequency of intramammary infection and that of clinical mastitis and improves milk quality, as shown by a reduction in the levels of somatic cell count (SCC)/ml in milk, decreased plasmin activity and increased oxidative stability of milk. However, a recent study from the Netherlands suggested that vitamin E supplementation at the 3000 IU/cow per day level during the dry period when combined with high levels of plasma vitamin E at dry-off (>14.5 μmol/l) increases the incidence of mastitis. Data from previously unpublished survey studies and those from published vitamin E feeding trials, in which high levels of blood vitamin E were observed, were reanalyzed. All farms selected for the analysis implemented oral administration of vitamin E at the 3000 IU/cow per day level throughout or during the late dry period (4 weeks before the expected day of parturition). Dairy cows were divided into three groups, depending on blood α-tocopherol levels at dry-off: high (>6.25 μg/ml), medium (between 6.25 and 4.25 μg/ml) and low (<4.25 μg/ml). Data indicate that there were no differences in the incidence of mastitis and in the level of SCC/ml of milk between the three groups. Thus, supplementation of 3000 IU vitamin E/cow per day in the late dry period remains recommended because it is generally associated with decreased risk of mastitis. Conditional or opposite effects have not been repeated and require further research before changing recommendations for vitamin E supplementation. © The Animal Consortium 2011. Source

Labrou N.E.,Agricultural University of Athens
Current Protein and Peptide Science

Random mutagenesis is a powerful tool for generating enzymes, proteins, entire metabolic pathways, or even entire genomes with desired or improved properties. This technology is used to evolve genes in vitro through an iterative process consisting of recombinant generation. Coupled with the development of powerful high-throughput screening or selection methods, this technique has been successfully used to solve problems in protein engineering. There are many methods to generate genetic diversity by random mutagenesis and to create combinatorial libraries. This can be achieved by treating DNA or whole bacteria with various chemical mutagens, by passing cloned genes through mutator strains, by "error-prone" PCR mutagenesis, by rolling circle error-prone PCR, or by saturation mutagenesis. The next sections of this review article focus on recent advances in techniques and methods used for in vitro directed evolution of enzymes using random mutagenesis. Selected examples, highlighting successful applications of these methods, are also presented and discussed. © 2010 Bentham Science Publishers Ltd. Source

Markou G.,Agricultural University of Athens
Bioresource Technology

In this study the biomass composition alteration of the cyanobacterium Arthrospira (Spirulina) platensis under various amounts of limited phosphorus is studied. It was observed that the alteration of the compounds of the biomass occurred gradually as the phosphorus became limited. Carbohydrates and lipids increased from about 9% up to 65% and from about 4.9% up to 7.5%, respectively, while proteins decreased from about 46.5% to 25% as the phosphorus became limited. The increasing of carbohydrates and lipids in addition to the decrease of proteins resulted to an increase of the carbon to nitrogen (C/. N) ratio from about 4.6 to 12.2. © 2012 Elsevier Ltd. Source

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