Approval voting ion dichotomous preferences

The aim of this paper is to find normative foundations of Approval Voting. In order to show that Approval Voting is the only social choice function that satisfies anonymity, neutrality, strategy-proofness and strict monotonicity we rely on an intermediate result which relates strategy-proofness of a social choice function to the properties of Independence of Irrelevant Alternatives and monotonicity of the corresponding social welfare function. Afterwards we characterize Approval Voting by means of strict symmetry, neutrality and strict monotonicity and relate this result to May's Theorem. Finally, we show that it is possible to substitute the property of strict monotonicity by the one efficiency of in the second characterization.

Passes fins a futurs canvis legislatius a l’àmbit penal en material de conducció de vehicles. Estudi quantitatiu de cocaïna i heroïna en saliva de conductors

Estudi de la presència de cocaïna i opiacis en saliva, en subjectes sospitosos de conduir sota els efectes de les drogues. Aplicació d’un test d’immunoassaig (Cozart). Confirmació i quantificació dels resultats positius (CG-EM). Comparació amb alteracions clíniques en els subjectes. No hi ha diferències entre concentracions de droga i signes clínics avaluades

Execució penal de sancions a conductors sota els efectes de drogues d’abús basats en estudi de saliva: ingerència i repercussió futura en el Codi penal

El consum de drogues no institucionalitzades té una important dimensió epidemiològica. En l'actualitat augmenta el consum de cocaïna i de cànnabis i s'estabilitza o disminueix el de opiacis. En la majoria dels països hi ha una relació entre la drogoaddicció i el delicte. Objectius: 1) Obtenir dades sociodemogràfiques en una població detinguda en els jutjats de guàrdia que passen a disposició judicial; 2) Obtenir dades sanitàries referents a infecció per VIH, VHC I VHB; 3) Obtenir dades de consums de cocaïna, haxis, heroïna, benzodiazepines i drogues de síntesis; 4) Conèixer la correlació o concordança clínico-analítica i, 5) Valorar la relació de l'addicció a drogues amb la delictologia. Subjectes i Mètodes: Estudi realitzat en una població de 151 subjectes consumidors de drogues il·legals detinguts a disposició judicial al Jutjat de guàrdia de la ciutat de Barcelona. Temps de l'estudi: 1,5 anys. Mètodes: Administració d'un qüestionari amb dades sociodemogràfiques, sanitàries i de consums de tòxics. Obtenció d'una mostra d'orina que es va analitzar per immunoassaig en l'analitzador AsXym (*Abbot). Els resultats es van interpretar com positius o negatius segons el punt de tall establert per al mètode. Resultats: El perfil de la mostra és un home solter, edat mitjana de 31.4 anys, amb estudis primaris i sense professió qualificada. La droga il·legal més consumida és la cocaïna, 77,5%, seguida dels opiacis 62,9%, del cànnabis 60,3% i benzodiazepines 61.6% (auto-medicades 40,9%). La prevalença de HIV va ser del 16,7%, VHC 37,9% i VHB 19,1%. La via intravenosa és utilitzada pel 46% dels cocainòmans i pel 53.8% del heroinòmans. Un 45.5% tenen signes compatibles amb UDVP. Només un 14.2% presentava signes de deteriorament físic i un 23.1% una clara síndrome d’abstinència. Existeix un 74.3% de correlació o concordança clínico-analítica. El delicte més relacionat amb el consum de drogues va ser els delictes contra la propietat. Conclusions i Discusió: Es detecta un alt consum de cocaïna i disminució de l'heroïna. El consum de cànnabis i benzodiazepines és elevat. Els delictes contra la propietat estan associats al consum de drogues il·legals. Propostes: L'estudi té aplicabilitat en medicina forense. El screening rutinari d'orina en població detinguda és una mesura d'utilitat. Permet obtenir dades objectives quan se sol·liciten informes de drogoaddicció als perits. Els detinguts poden beneficiar-se de circumstàncies modificadores de la responsabilitat criminal en cas de ser consumidors de tòxics, d’acord amb la legislació actual. Els lletrats i l'autoritat judicial tindran una prova objectiva en les seves actuacions per poder resoldre amb més coneixement els procediments on es troben implicats els consumidors de drogues d'abús.

Metallic and nonmetallic shine in luster: An elastic ion backscattering study

Luster is a metal glass nanocomposite layer first produced in the Middle East in early Islamic times ( 9th AD) made of metal copper or silver nanoparticles embedded in a silica-based glassy matrix. These nanoparticles are produced by ion exchange between Cu+ and Ag+ and alkaline ions from the glassy matrix and further growth in a reducing atmosphere. The most striking property of luster is its capability of reflecting light like a continuous metal layer and it was unexpectedly found to be linked to one single production parameter: the presence of lead in the glassy matrix composition. The purpose of this article is to describe the characteristics and differences of the nanoparticle layers developed on lead rich and lead free glasses. Copper luster layers obtained using the ancient recipes and methods are analyzed by means of elastic ion backscattering spectroscopy associated with other analytical techniques. The depth profile of the different elements is determined, showing that the luster layer formed in lead rich glasses is 5–6 times thinner and 3–4 times Cu richer. Therefore, the metal nanoparticles are more densely packed in the layer and this fact is related to its higher reflectivity. It is shown that lead influences the structure of the metal nanoparticle layer through the change of the precipitation kinetics

Vacancy and interstitial depth profiles in ion-implanted silicon

An experimental method of studying shifts between concentration-versus-depth profiles of vacancy- and interstitial-type defects in ion-implanted silicon is demonstrated. The concept is based on deep level transient spectroscopy measurements utilizing the filling pulse variation technique. The vacancy profile, represented by the vacancy¿oxygen center, and the interstitial profile, represented by the interstitial carbon¿substitutional carbon pair, are obtained at the same sample temperature by varying the duration of the filling pulse. The effect of the capture in the Debye tail has been extensively studied and taken into account. Thus, the two profiles can be recorded with a high relative depth resolution. Using low doses, point defects have been introduced in lightly doped float zone n-type silicon by implantation with 6.8 MeV boron ions and 680 keV and 1.3 MeV protons at room temperature. The effect of the angle of ion incidence has also been investigated. For all implantation conditions the peak of the interstitial profile is displaced towards larger depths compared to that of the vacancy profile. The amplitude of this displacement increases as the width of the initial point defect distribution increases. This behavior is explained by a simple model where the preferential forward momentum of recoiling silicon atoms and the highly efficient direct recombination of primary point defects are taken into account.

White luminescence from Si+ and C+ ion-implanted SiO2 films

The microstructural and optical analysis of SiO2 layers emitting white luminescence is reported. These structures have been synthesized by sequential Si+ and C+ ion implantation and high-temperature annealing. Their white emission results from the presence of up to three bands in the photoluminescence (PL) spectra, covering the whole visible spectral range. The microstructural characterization reveals the presence of a complex multilayer structure: Si nanocrystals are only observed outside the main C-implanted peak region, with a lower density closer to the surface, being also smaller in size. This lack of uniformity in their density has been related to the inhibiting role of C in their growth dynamics. These nanocrystals are responsible for the band appearing in the red region of the PL spectrum. The analysis of the thermal evolution of the red PL band and its behavior after hydrogenation shows that carbon implantation also prevents the formation of well passivated Si/SiO2 interfaces. On the other hand, the PL bands appearing at higher energies show the existence of two different characteristics as a function of the implanted dose. For excess atomic concentrations below or equal to 10%, the spectra show a PL band in the blue region. At higher doses, two bands dominate the green¿blue spectral region. The evolution of these bands with the implanted dose and annealing time suggests that they are related to the formation of carbon-rich precipitates in the implanted region. Moreover, PL versus depth measurements provide a direct correlation of the green band with the carbon-implanted profile. These PL bands have been assigned to two distinct amorphous phases, with a composition close to elemental graphitic carbon or stoichiometric SiC.

Modifications in the Si valence band after ion-beam-induced oxidation

The changes undergone by the Si surface after oxygen bombardment have special interest for acquiring a good understanding of the Si+-ion emission during secondary ion mass spectrometry (SIMS) analysis. For this reason a detailed investigation on the stoichiometry of the builtup surface oxides has been carried out using in situ x-ray photoemission spectroscopy (XPS). The XPS analysis of the Si 2p core level indicates a strong presence of suboxide chemical states when bombarding at angles of incidence larger than 30°. In this work a special emphasis on the analysis and interpretation of the valence band region was made. Since the surface stoichiometry or degree of oxidation varies with the angle of incidence, the respective valence band structures also differ. A comparison with experimentally measured and theoretically derived Si valence band and SiO2 valence band suggests that the new valence bands are formed by a combination of these two. This arises from the fact that Si¿Si bonds are present on the Si¿suboxide molecules, and therefore the corresponding 3p-3p Si-like subband, which extends towards the Si Fermi level, forms the top of the respective new valence bands. Small variations in intensity and energy position for this subband have drastic implications on the intensity of the Si+-ion emission during sputtering in SIMS measurements. A model combining chemically enhanced emission and resonant tunneling effects is suggested for the variations observed in ion emission during O+2 bombardment for Si targets.

Configurational statistical model for the damaged structure of silicon oxide after ion implantation

A configurational model for silicon oxide damaged after a high-dose ion implantation of a nonreactive species is presented. Based on statistics of silicon-centered tetrahedra, the model takes into account not only the closest environment of a given silicon atom, but also the second neighborhood, so it is specified whether the oxygen attached to one given silicon is bridging two tetrahedra or not. The frequencies and intensities of infrared vibrational bands have been calculated by averaging over the distributions and these results are in agreement with the ones obtained from infrared experimental spectra. Likewise, the chemical shifts obtained from x-ray photoelectron spectroscopy (XPS) analysis are similar to the reported values for the charge-transfer model of SiOx compounds.

Anomalous crossover between thermal and shot noise in macroscopic diffusive conductors

We predict the existence of an anomalous crossover between thermal and shot noise in macroscopic diffusive conductors. We first show that, besides thermal noise, these systems may also exhibit shot noise due to fluctuations of the total number of carriers in the system. Then we show that at increasing currents the crossover between the two noise behaviors is anomalous, in the sense that the low-frequency current spectral density displays a region with a superlinear dependence on the current up to a cubic law. The anomaly is due to the nontrivial coupling in the presence of the long-range Coulomb interaction among the three time scales relevant to the phenomenon, namely, diffusion, transit, and dielectric relaxation time.

Shot noise anomalies in elastic nondegenerate diffusive conductors

We present a theoretical investigation of shot-noise properties in nondegenerate elastic diffusive conductors. Both Monte Carlo simulations and analytical approaches are used. Two interesting phenomena are found: (i) the display of enhanced shot noise for given energy dependences of the scattering time, and (ii) the recovery of full shot noise for asymptotic high applied bias. The first phenomenon is associated with the onset of negative differential conductivity in energy space that drives the system towards a dynamical electrical instability in excellent agreement with analytical predictions. The enhancement is found to be strongly amplified when the dimensionality in momentum space is lowered from three to two dimensions. The second phenomenon is due to the suppression of the effects of long-range Coulomb correlations that takes place when the transit time becomes the shortest time scale in the system, and is common to both elastic and inelastic nondegenerate diffusive conductors. These phenomena shed different light in the understanding of the anomalous behavior of shot noise in mesoscopic conductors, which is a signature of correlations among different current pulses.

The role of energy correlations on Coulomb suppression in ballistic conductors contacted to degenerate reservoirs

Coulomb suppression of shot noise in a ballistic diode connected to degenerate ideal contacts is analyzed in terms of the correlations taking place between current fluctuations due to carriers injected with different energies. By using Monte Carlo simulations we show that at low frequencies the origin of Coulomb suppression can be traced back to the negative correlations existing between electrons injected with an energy close to that of the potential barrier present in the diode active region and all other carriers injected with higher energies. Correlations between electrons with energy above the potential barrier with the rest of electrons are found to influence significantly the spectra at high frequency in the cutoff region.