5,055 research outputs found

    Proposal for a Supersymmetric Standard Model

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    The fact that neutrinos are massive suggests that the minimal supersymmetric standard model (MSSM) might be extended in order to include three gauge-singlet neutrino superfields with Yukawa couplings of the type H2LνcH_2 L \nu^c. We propose to use these superfields to solve the μ\mu problem of the MSSM without having to introduce an extra singlet superfield as in the case of the next-to-MSSM (NMSSM). In particular, terms of the type νcH1H2\nu^c H_1 H_2 in the superpotential may carry out this task spontaneously through sneutrino vacuum expectation values. In addition, terms of the type (νc)3(\nu^c)^3 avoid the presence of axions and generate effective Majorana masses for neutrinos at the electroweak scale. On the other hand, these terms break lepton number and R-parity explicitly implying that the phenomenology of this model is very different from the one of the MSSM or NMSSM. For example, the usual neutralinos are now mixed with the neutrinos. For Dirac masses of the latter of order 10410^{-4} GeV, eigenvalues reproducing the correct scale of neutrino masses are obtained.Comment: 9 pages, latex, title modified. Final version published in PR

    Anatomical pathways for auditory memory II: information from rostral superior temporal gyrus to dorsolateral temporal pole and medial temporal cortex

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    Auditory recognition memory in non-human primates differs from recognition memory in other sensory systems. Monkeys learn the rule for visual and tactile delayed matching-to-sample within a few sessions, and then show one-trial recognition memory lasting 10–20 min. In contrast, monkeys require hundreds of sessions to master the rule for auditory recognition, and then show retention lasting no longer than 30–40 s. Moreover, unlike the severe effects of rhinal lesions on visual memory, such lesions have no effect on the monkeys' auditory memory performance. The anatomical pathways for auditory memory may differ from those in vision. Long-term visual recognition memory requires anatomical connections from the visual association area TE with areas 35 and 36 of the perirhinal cortex (PRC). We examined whether there is a similar anatomical route for auditory processing, or that poor auditory recognition memory may reflect the lack of such a pathway. Our hypothesis is that an auditory pathway for recognition memory originates in the higher order processing areas of the rostral superior temporal gyrus (rSTG), and then connects via the dorsolateral temporal pole to access the rhinal cortex of the medial temporal lobe. To test this, we placed retrograde (3% FB and 2% DY) and anterograde (10% BDA 10,000 mW) tracer injections in rSTG and the dorsolateral area 38DL of the temporal pole. Results showed that area 38DL receives dense projections from auditory association areas Ts1, TAa, TPO of the rSTG, from the rostral parabelt and, to a lesser extent, from areas Ts2-3 and PGa. In turn, area 38DL projects densely to area 35 of PRC, entorhinal cortex (EC), and to areas TH/TF of the posterior parahippocampal cortex. Significantly, this projection avoids most of area 36r/c of PRC. This anatomical arrangement may contribute to our understanding of the poor auditory memory of rhesus monkeys

    Isoscaling and the high Temperature limit

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    This study shows that isoscaling, usually studied in nuclear reactions, is a phenomenon common to all cases of fair sampling. Exact expressions for the yield ratio R21R_{21} and approximate expressions for the isoscaling parameters α\alpha and β\beta are obtained and compared to experimental results. It is concluded that nuclear isoscaling is bound to contain a component due to sampling and, thus, a words of caution is issued to those interested in extracting information about the nuclear equation of state from isoscaling.Comment: 7 pages, 1 figur

    3D photonic crystals from highly monodisperse FRET-based red luminescent PMMA spheres

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    Red-luminescent PMMA spheres containing a Förster resonance energy transfer (FRET) pair were synthesized via a two-step polymerization method. Two reaction parameters, time and monomer volume, are scanned in order to tune the sphere diameter in the 250-500 nm range. Further the polydispersity of the spheres is kept low, at ca. 3%, regardless of sphere diameter or dye concentration. A thorough optical characterization via spectroscopy and time resolved measurements shows a FRET efficiency of over 40% before concentration quenching effects take place, allowing for a precise tuning of their emission in the red region of the visible spectrum. The high quality of these spheres makes them suitable to fabricate self-assembled 3D photonic crystals which act as photonic environment to modify the spectral properties of the FRET pair via Bragg diffraction.España Mineco MAT2012-31659Comunidad de Madrid S2013/MIT-274

    Pragmática de la desinformación. Un estudio del leak de Prism a través de las reacciones de los gobiernos de Estados Unidos, Alemania y Venezuela

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    En este trabajo se exponen las técnicas de desinformación más comunes que se evidencian en el leak sobre el proyecto Prism de la NSA y sus inmediatas reacciones por parte de los gobiernos de Estados Unidos, Alemania y Venezuela. Para lograr este objetivo, se ha realizado un análisis cualitativo de base interpretativa al discurso de los mandatarios de los tres países, a través de las informaciones recogidas en medios digitales, mediante la localización, criba especializada, métodos de criterio de fuentes y selección aleatoria por metodología de semana construida. Los resultados evidencian el uso de al menos 11 estra- tagemas de desinformación

    Genetic algorithm optimization of entanglement

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    We present an application of a genetic algorithmic computational method to the optimization of the concurrence measure of entanglement for the cases of one dimensional chains, as well as square and triangular lattices in a simple tight-binding approach in which the hopping of electrons is much stronger than the phonon dissipationComment: 26 pages with 13 figures, based on Chapter 3 of the Master thesis of the first author defended at IPICyT, San Luis Potosi, Mx, on 22nd of February 2006, similar to the published version [Fig. 5 left out but contains the Appendix figure

    Development of the determination of melatonin in blueberries using LC-MS/MS

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    Melatonin (MLT) is an indolamine that presents a functional activity with a broad spectrum of action, highlighting its antioxidant, anti-inflammatory and immunomodulatory and anti-apoptotic capacity. It is a widely distributed hormone, found in most of the foods that make up a normal diet. There are many studies that analyze the MLT content in different foods and using different techniques. However, very little research has focused on analyzing MLT concentration in blueberries. Therefore, the aim of this study was the development of a method for the extraction and determination of MLT in blueberries (Vaccinium corymbosum), using liquid chromatography-tandem mass spectrometry (LC-MS/MS), which has been shown to be one of the most reliable and precise techniques for this type of analysis. It was determined that using methanol as an extraction solvent obtained greater efficiency than using acetonitrile. Likewise, the highest recovery percentages were achieved with the BOND ELUT PLEXA solid phase extraction (SPE) cartridges. With the optimization of the extraction process and subsequent analysis, it was determined that the blueberries used in this study had an MLT concentration of 0.173 ± 0.028 ng/g

    Recommendations for the Management of Construction and Demolition Waste in Treatment Plants

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    Construction and demolition waste consists approximately of one third waste generated in the European Union. The recycling of this stream waste will provide ecological and sustainable benefits. Recycled aggregates from construction and demolition waste are clearing a path into civil constructions, as substitutes for natural aggregates. The possible applications of recycled aggregates on infrastructure construction projects will depend on the quality of the recycled aggregates mainly. This will be determined by the nature and the origin of the construction and demolition waste, and the treatment system undergone. Hence, this work proposes recommendations for the handling of construction and demolition waste in treatment plants
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