Building an Open Social Learning Community Around a DSpace Repository on Statistics

4th International Conference on Open RepositoriesThis presentation was part of the session : Conference PostersIn this paper we describe a project which aims to build an open social learning community around a learning object repository (LOR) based on DSpace containing learning resources about Statistics. We combine the preservation capabilities of DSpace with the facilities of a tagging mechanism such as Delicious. On top of this ensemble we intend to build a new browsing interface for improving users' learning experience when using the LOR. We also intend to gather and analyze usage data in order to better understand the real learning process in virtual learning environments.Spanish Government Grant under Refs. TIN2006-15107-C06 and EA2008-015

A Metafrontier Analysis of Technical Efficiency of Selected European Agricultures

Technical efficiency refers to the situation where it is impossible for a firm to produce, with the given know-how, (1) a larger output from the same inputs or (2) the same output with less of one or more inputs without increasing the amount of other inputs. In practice, the interest is on the relative position in terms of efficiency of a particular firm with respect to others. Therefore, technical efficiency is characterised by the relationship between observed production and some ideal or potential production (Greene, 1993). Although the beginning of the efficiency work can be traced to the 1950s (Farrell, 1957), there have been a growing interest on its use in benchmarking performance, predominantly as a means of identifying best practice and improving the efficiency of resource use within the agricultural industry (e.g., Defra 2004, SAC 2009). This paper deals with the estimation of technical efficiency for the agricultural sectors in several European countries and moreover, it aims to compare the efficiency amongst them using a metafrontier analysis. The use of this type of analysis is justified because a frontier, which represents the best available technology within a particular region/country cannot be strictly compared across other regions/countries, unless they operate under the same production set. The metafrontier analysis has been developed in a number of studies (Battese and Rao, 2002; Nkamleu et al., 2006; Chen and Song, 2006; O‟Donnell et al., 2008.) The metafrontier analysis in this paper, which uses data from the Farm Accountancy data Network (FADN), was focused on four farm types: two specialised farming types (i.e., specialist cereals, oilseed and protein crops and specialist dairying) and two more mixed farming sets (i.e., general field cropping and mixed farms), and was applied to a total of 11 countries namely Belgium, Denmark, France, Germany, Hungary, Ireland, Italy, Netherlands, Poland, Spain and the UK. For most of the countries the information was available from 1995 until 2007, excepting Hungary and Poland, for which it was available only since 2004. Also note that not all the farm types were available for all the countries. The structure of the paper is as follows: it starts presenting an overview of the metafrontier analysis used to compare technical efficiency amongst the European countries. It is followed by the empirical work, which comprises a description of the data used, the estimation and discussion of the results. Finally we present conclusions.Research and Development/Tech Change/Emerging Technologies,

Anomalous temperature dependence of the band-gap in Black Phosphorus

Black Phosphorus (BP) has gained renewed attention due to its singular anisotropic electronic and optical properties that might be exploited for a wide range of technological applications. In this respect, the thermal properties are particularly important both to predict its room temperature operation and to determine its thermoelectric potential. From this point of view, one of the most spectacular and poorly understood phenomena is, indeed, the BP temperature-induced band-gap opening: when temperature is increased the fundamental band-gap increases instead of decreasing. This anomalous thermal dependence has also been observed, recently, in its monolayer counterpart. In this work, based on \textit{ab-initio} calculations, we present an explanation for this long known, and yet not fully explained, effect. We show that it arises from a combination of harmonic and lattice thermal expansion contributions, which are, in fact, highly interwined. We clearly narrow down the mechanisms that cause this gap opening by identifying the peculiar atomic vibrations that drive the anomaly. The final picture we give explains both the BP anomalous band-gap opening and the frequency increase with increasing volume (tension effect).Comment: Published in Nano Letter

The Suyama-Yamaguchi consistency relation in the presence of vector fields

We consider inflationary models in which vector fields are responsible for part or eventually all of the primordial curvature perturbation \zeta. Such models are phenomenologically interesting since they naturally introduce anisotropies in the probability distribution function of the primordial fluctuations that can leave a measurable imprint in the cosmic microwave background. Assuming that non-Gaussianity is generated due to the superhorizon evolution, we use the \delta N formalism to do a complete tree level calculation of the non-Gaussianity parameters f_{NL} and \tau_{NL} in the presence of vector fields. We isolate the isotropic pieces of the non-Gaussianity parameters, which anyway have contributions from the vector fields, and show that they obey the Suyama-Yamaguchi consistency relation \tau^{iso}_{NL}>=(6/5f^{iso}_{NL})^2. Other ways of defining the non-Gaussianity parameters, which could be observationally relevant, are stated and the respective Suyama-Yamaguchi-like consistency relations are obtained.Comment: LaTeX file, 11 pages. v2: a few minor changes, references added and updated. v3: version to be published in Modern Physics Letters

A metafrontier approach to measuring technical efficiencies across the UK dairy sector

A regional approach is applied to measure technical efficiencies on dairy farms which employs the deterministic metafrontier approach. We construct six super regions for the UK, i.e. Eastern, Western, Northern England, Wales, Scotland and Northern Ireland. Data are collected through three different administrative systems, all be it under the same FADN guidance. We find for dairy farming comparative indicators of performance in all three data sets. The stochastic frontier approach is applied to construct 6 regional frontiers and a pooled (UK) dataset for comparison. A likelihood ratio test rejects the null hypothesis that these regions operate under a common frontier which may indicate bias in previous attempts to measure dairying efficiency at the country level. Mean technical efficiencies are high for the period 2005 to 2008, though there is some indication that little technical progress has occurred since decoupling of CAP payments from production in all regions. The metafrontier presents estimates against a common technology and mean scores range from below 0.50 for the English regions and Northern Ireland, 0.52 for Wales and 0.56 for Scotland. This paper promotes the application of the deterministic metafrontier approach for similar sub-country studies.Stochastic Production Frontiers, Metafrontiers, UK Farm Account Data, Dairy farming., Agricultural and Food Policy, Q12, D24, C23, C51,

Antimicrobial and antioxidant potentials of essential oil and acetone extract of Myristica fragrans Houtt. (aril part)

The antifungal, antibacterial, and antioxidant potentials of essential oil and acetone extract were carried out by different techniques. In poison food medium method, the essential oil showed complete zones of inhibition against Fusarium graminearum at the all tested doses. For other tested fungi and bacteria, they gave good to moderate zone inhibition. The antioxidant activity was evaluated by measuring peroxide, thiobarbituric acid and total carbonyl values of rapeseed oil at fixed time intervals. Both the extract and essential oil showed strong antioxidant activity in comparison with butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). In addition, their inhibitory action in linoleic acid system was studied by monitoring peroxide concentration in emulsion during incubation. The results were well correlated with above values. Their radical scavenging capacity was carried out on 2,2′-diphenyl-1-picrylhydracyl (DPPH) radicalm, and they showed strong scavenging activity in comparison with synthetic antioxidants. Their reducing power was also determined, which also proved strong antioxidant capacity of essential oil and extract. Gas chromatographic-mass spectroscopy studies on essential oil resulted in the identification of 49 components representing 96.49% of the total amount, and the major component was sabinene (20.22%), followed by terpinen-4-ol (12.08%), safrole (10.32%), α-pinene (9.7%), β-phellandrene (6.56%), and γ-terpinene (5.93%). The acetone extract showed the presence of 23 components representing 71.66% of the total amount. The major components were isocroweacin (18.92%), elemicin (17.68%), methoxyeugenol (8.13%), linoleic acid (4.12%), dehydrodiisoeugenol (4.06%), palmitic acid (2.8%), and trans-isoeugenol (2.76%). © 2005 Institute of Food Technologists.Fil: Singh, Gurdip. Deen Dayal Upadhyay Gorakhpur University India; IndiaFil: Marimuthu, P.. Deen Dayal Upadhyay Gorakhpur University India; IndiaFil: De Heluani, Carola S.. Universidad Nacional de Tucumán; ArgentinaFil: Catalan, Cesar Atilio Nazareno. Universidad Nacional de Tucumán; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentin

Topology and Dynamics in Complex Networks: The Role of Edge Reciprocity

A key issue in complex systems regards the relationship between topology and dynamics. In this work, we use a recently introduced network property known as steering coefficient as a means to approach this issue with respect to different directed complex network systems under varying dynamics. Theoretical and real-world networks are considered, and the influences of reciprocity and average degree on the steering coefficient are quantified. A number of interesting results are reported that can assist the design of complex systems exhibiting larger or smaller relationships between topology and dynamics

Gravitational Wave Signatures of Highly Magnetized Neutron Stars

Motivated by the recent gravitational wave detection by the LIGO-VIRGO observatories, we study the Love number and dimensionless tidal polarizability of highly magnetized stars. We also investigate the fundamental quasi-normal mode of neutron stars subject to high magnetic fields. To perform our calculations we use the chaotic field approximation and consider both nucleonic and hyperonic stars. As far as the fundamental mode is concerned, we conclude that the role played by the constitution of the stars is far more relevant than the intensity of the magnetic field and if massive stars are considered, the ones constituted by nucleons only present frequencies somewhat lower than the ones with hyperonic cores, a feature that can be used to point out the real internal structure of neutron stars. Moreover, our studies clearly indicate that strong magnetic fields play a crucial role in the deformability of low mass neutron stars, with possible consequences on the interpretation of the detected gravitational waves signatures.Comment: 24 pages, 4 figures, 6 table