Electrodynamics of quasi-two-dimensional BEDT-TTF charge transfer salts

We consider the millimeter-wave electrodynamics specific to quasi-two-dimensional conductors and superconductors based on the organic donor molecule BEDT-TTF. Using realistic physical parameters, we examine the current polarizations that result for different oscillating (GHz) electric and magnetic field polarizations. We show that, in general, it is possible to discriminate between effects (dissipation and dispersion) due to in-plane and interlayer ac currents. However, we also show that it is not possible to selectively probe any single component of the in-plane conductivity tensor, and that excitation of interlayer currents is strongly influenced by the sample geometry and the electromagnetic field polarization.Comment: 5 pages including 3 figures Minor correction to figure

Complex Response Function of Magnetic Resonance Spectrometers

A vectorial analysis of magnetic resonance spectrometers, based on traveling wave resonators and including the reference arm and the automatic control of frequency, has been developed. The proposed model, valid also for stationary wave resonators, gives the response function of the spectrometer for any working condition, including scalar detectors with arbitrary response law and arbitrary excitation frequency. The purely dispersive and purely absorptive linear responses are discussed in detail for different scalar detectors. The developed approach allows for optimizing the performances of the spectrometer and for obtaining the intrinsic lineshape of the sample in a very broad range of working conditions. More complex setups can be modeled following the proposed scheme.Comment: PDF Acrobat 4.0 file, 15 pages, 2 figures, revised version with added reference and corrected typo

Threshold-based Naïve Bayes classifier

The Threshold-based Naive Bayes (Tb-NB) classifier is introduced as a (simple) improved version of the original Naive Bayes classifier. Tb-NB extracts the sentiment from a Natural Language text corpus and allows the user not only to predict how much a sentence is positive (negative) but also to quantify a sentiment with a numeric value. It is based on the estimation of a single threshold value that concurs to define a decision rule that classifies a text into a positive (negative) opinion based on its content. One of the main advantage deriving from Tb-NB is the possibility to utilize its results as the input of post-hoc analysis aimed at observing how the quality associated to the different dimensions of a product or a service or, in a mirrored fashion, the different dimensions of customer satisfaction evolve in time or change with respect to different locations. The effectiveness of Tb-NB is evaluated analyzing data concerning the tourism industry and, specifically, hotel guests' reviews from all hotels located in the Sardinian region and available on Booking.com. Moreover, Tb-NB is compared with other popular classifiers used in sentiment analysis in terms of model accuracy, resistance to noise and computational efficiency

Preliminary Results of the Use of Sowing Time and Variety Choice as Techniques of Adaptability of Durum Wheat (Triticum durum Desf.) to Temperature Increases

In the 21st century, global climate change is a key concern for countries all over the world as, in the future, crops will face several extreme events, including an increase of 2–4◦C in the mean temperature with a possible consequent reduction in yield. Wheat (Triticum durum Desf) is one of the most important foods as it provides 20% of the protein for the world population. Since temperature is one of the most limiting factors of crop development, the aim of this trial was to verify the agronomic response of durum wheat to a temperature increase of about 1.5–2.0◦C through the use of short-time adjustment techniques, such as sowing time and variety choice. The experiment foresaw the comparison between two different temperature conditions (ordinary, OT—in the open field, and high, HT—under a polyethylene tunnel), two sowing times (ordinary—OS, and delayed—DS), and three varieties (Ofanto, modern variety; Cappelli, traditional variety; and a mix of the two). HT conditions caused a decline in the wheat yield (−52.5%), but without differences between the two sowing times. The grain quality resulted positively when affected by late sowing times with an increase in 1000 seeds weight and protein percentages and a decrease in shrunken grains. Therefore, it seems that in areas characterized by high temperatures, delayed sowing can improve grain quality without reducing yield quantity compared to ordinary sowing times

E-commerce and e-procurement: an outsourcing perspective

The make or buy dilemma has been largely analyzed in the field of Information Systems. The main reason for this type of literature thriving so much is that the Information Systems function was one of the first enterprise areas to be externalized. If traditionally only few activities, distant from the core business of the enterprises, have been externalized with the sole objective of gaining efficiency, in the late Nineties externalization of real company functions has started to be considered again, in some instances concerning activities that have always been considered core business. The role played by the management of organizational interdependencies was stressed and the fact that outsourcing was perceived according to solutions of organizational engineering was highlighted, steering enterprises towards new organizational design criteria. In fact, make or buy decisions require more and more that organizational variables be structured by processes and not by functions, precisely to ease the management of organizational interdependencies and make externalization decisions more transparent and objectively measurable. The research question of this paper aims at understanding how much can a particular form of electronic commerce, such as e-procurement, be categorized as a special form of outsourcing, intending this phenomenon as a hybrid organizational form, halfway between hierarchy and market. In order to categorize the outsourcing phenomenon from a theoretical standpoint, the Transaction Cost Theory (TCT) has been used, while the research method consists of a case study. In this paper the attention will be focused on a particular process only, i.e., procurement, in relation to the activities involved in the externalization process. The paper will analyze an outsourcing case applied to the entire macro-process of procurement. The conclusions will highlight the evolving trends in this research field, which appears to be affected by substantial changes and to be increasingly more volatile and influenced by multiple factors that are not always easily recognizable and measurable. The purpose of this paper in fact is to give a contribution to the formalization of an application subject, namely, externalization of procurement, largely diffused in practice although scarcely developed from a theoretical standpoint

Quantum melting of the quasi-two-dimensional vortex lattice in kappa-(ET)2Cu(NCS)2

We report torque magnetization measurements in regions of the mixed state phase diagram (${\bf B}\sim\mu_o{\bf H}_{c2}$ and T$_c$/$10^3$) of the organic superconductor $\kappa-$(ET)$_2$Cu(NCS)$_2$ where quantum fluctuations are expected to dominate thermal effects. Over most of the field range below the irreversibility line (${\bf B}_{irr}$), magneto-thermal instabilities are observed in the form of flux jumps. The abrupt cessation of these instabilities just below ${\bf B}_{irr}$ indicates a quantum melting transition from a quasi-two-dimensional vortex lattice phase to a quantum liquid phase.Comment: 8 pages (inc. Figs), accepted for publication in Phys. Rev. Let