Measuring the W-t-b Interaction at the ILC

The large top quark mass suggests that the top plays a pivotal role in Electroweak symmetry-breaking dynamics and, as a result, may have modified couplings to Electroweak bosons. Hadron colliders can provide measurements of these couplings at the ~10% level, and one of the early expected triumphs of the International Linear Collider is to reduce these uncertainties to the per cent level. In this article, we propose the first direct measurement of the Standard Model W-t-b coupling at the ILC, from measurements of t tbar-like signals below the t tbar production threshold. We estimate that the ILC with 100 fb^{-1} can measure a combination of the coupling and top width to high precision, and when combined with a direct measurement of the top width from the above-threshold scan, results in a model-independent measurement of the W-t-b interaction of the order of ~ 3%

Plasticity in the Echolocation Inventory of Mormopterus minutus (Chiroptera, Molossidae)

We recorded the echolocation behavior of the molossid bat Mormopterus minutus, a species that uses a plastic call inventory. During its foraging activity, M. minutus searches for insects emitting rather long and narrow-band echolocation calls. Search call design however, can vary noticeably even in a continuous foraging pass. While echolocating in different flying conditions M. minutus uses several other call designs such as short CF, QCF, FM/QCF, FM and multi-harmonic FM, with or without harmonic overlap, and QCF/FM. Call plasticity characterizes most echolocation sequences, particularly in bats flying in open spaces. Call variation was also influenced by the presence of conspecifics. In those sequences containing echolocation calls from more than one bat, signals from different individuals were reliably identified. In contrast to other small molossids, the call designs in the echolocation inventory of M. minutus show a high level of plasticity. Our results suggest that M. minutus has combined the advantages of emitting several call designs, as shown by molossids, with the advantages of manipulating one signal design as shown by vespertilionids within the same sonar inventory.Peer reviewe

The generation of student engagement as a cognition-affect-behaviour process in a Twitter learning experience

Twitter is a microblog that allows users to interact about a topic in online discussion. This makes it an interesting interactive tool with possibilities to increase student engagement and learning performance through active collaboration in an informal learning environment. However, few articles take a quantitative approach to investigate the creation of student engagement using this social networking site. To address this gap, we propose a series of activities conducted through Twitter to analyse the engagement generation process in a sample of 110 students in the first year of a business and administration degree at a large Spanish university. The results show that the engagement process is created through active collaborative learning and enjoyment, and that engaged students are more satisfied with the activity and perceive greater learning performance. This leads us to recommend teachers to encourage active and collaborative activities to make students more engaged and satisfied, and improve their performance.es consisting of applying the concepts studied in class to practical environments, and activities where students browse for online information and take part in a debate, are more enjoyable

Measuring the top Yukawa coupling at the ILC at sqrt(s) = 500 GeV

We report on the feasibility of the direct measurement of the top Yukawa coupling g_t at the International Linear Collider (ILC) during its first phase of operation with a center-of-mass energy of 500 GeV. The signal and background models incorporate the non-relativistic QCD corrections which enhance the production cross section near the t-tbar threshold. The e+e- -> t tbar H signal is reconstructed in the 6-jet + lepton and the 8-jet modes. The results from the two channels are combined. The background processes considered are e+e- -> t bbar W- / tbar b W+ (which includes e+e- -> t tbar), e+e- -> t tbar Z, and e+e- -> t tbar g* -> t tbar b bar. We use a realistic fast Monte-Carlo detector simulation. Signal events are selected using event shape variables, through jet clustering, and by identifying heavy flavor jets. Assuming a Higgs mass of 120 GeV, polarized electron and positron beams with (Pe-,Pe+) = (-0.8,+0.3), and an integrated luminosity of 1 ab-1, we estimate that the e+e- -> t tbar H events can be seen with a statistical significance of 5.2 sigma, corresponding to the relative top Yukawa coupling measurement accuracy of |Delta g_t / g_t| = 10%.Comment: 9 pages, 6 figures, to be submitted to Phys. Rev.

Spectral analysis methods for improved resolution and sensitivity: enhancing SPR and LSPR optical fiber sensing

Biochemical–chemical sensing with plasmonic sensors is widely performed by tracking the responses of surface plasmonic resonance peaks to changes in the medium. Interestingly, consistent sensitivity and resolution improvements have been demonstrated for gold nanoparticles by analyzing other spectral features, such as spectral inflection points or peak curvatures. Nevertheless, such studies were only conducted on planar platforms and were restricted to gold nanoparticles. In this work, such methodologies are explored and expanded to plasmonic optical fibers. Thus, we study—experimentally and theoretically—the optical responses of optical fiber-doped gold or silver nanospheres and optical fibers coated with continuous gold or silver thin films. Both experimental and numerical results are analyzed with differentiation methods, using total variation regularization to effectively minimize noise amplification propagation. Consistent resolution improvements of up to 2.2× for both types of plasmonic fibers are found, demonstrating that deploying such analysis with any plasmonic optical fiber sensors can lead to sensing resolution improvements.Fundação para a Ciência e Tecnologia | Ref. UIDB/50014/2020Fundação para a Ciência e Tecnologia | Ref. SFRH/BD/130674/2017Fundação para a Ciência e Tecnologia | Ref. CEECIND/00471/2017Xunta de Galicia | Ref. GRC ED431C 2020/09Fundação para a Ciência e Tecnologia | Ref. SFRH/BD/146784/201

LHC Discovery Potential for Non-Standard Higgs Bosons in the 3b Channel

In a variety of well motivated models, such as two Higgs Doublet Models (2HDMs) and the Minimal Supersymmetric Standard Model (MSSM), there are neutral Higgs bosons that have significantly enhanced couplings to b-quarks and tau leptons in comparison to those of the SM Higgs. These so called non-standard Higgs bosons could be copiously produced at the LHC in association with b quarks, and subsequently decay into b-quark pairs. However, this production channel suffers from large irreducible QCD backgrounds. We propose a new search strategy for non-standard neutral Higgs bosons at the 7 TeV LHC in the 3b's final state topology. We perform a simulation of the signal and backgrounds, using state of the art tools and methods for different sets of selection cuts, and conclude that neutral Higgs bosons with couplings to b-quarks of about 0.3 or larger, and masses up to 400 GeV, could be seen with a luminosity of 30 fb^{-1}. In the case of the MSSM we also discuss the complementarity between the 3b channel and the inclusive tau pair channel in exploring the supersymmetric parameter space.Comment: 14 pages, 3 figures, 4 tables, references added, published versio

Sistemas de manejo del suelo y sus efectos sobre el cultivo de agrios

En esta comunicación se plantean varios sistemas de manejo del suelo: laboreo mecánico con diferentes aperos (fresadora, cavadora y cultivador), técnicas de no laboreo y laboreo mixto. De cada sistema se ha determinado por un lado los consumos de energía, rendimientos y costes que supone; por otro, se ha seguido la evolución de ciertas propiedades físicas del suelo (densidad aparente, infiltración y compactación) y en especial las que se relacionan con el almacenamiento y contenido de agua. Finalmente se analiza los efectos que en la calidad y producción de frutos hayan podido tener cada uno de los diversos sistemas de manejo del suelo estudiados. Los resultados obtenidos corresponden a una experiencia realizada en la Comunidad Valenciana durante los tres últimos años

Growth and Branching of Gold nanoparticles Through MesoporousSilica Thin Films

Composite materials made of mesoporous oxide thin films containing metallic nanoparticles are of high interest in various fields, including catalysis, biosensing and non-linear optics. We demonstrate in this work the fabrication of such composite materials containing a sub-monolayer of gold nanoparticles (GNPs) of various shapes covered with mesoporous silica thin films. Additionally, the shape of the GNPs (and thus their optical properties) can be modified in situ through seeded growth and branching. Such growth proceeds upon wetting with HAuCl 4 solution, a surfactant (cetyltrimethylammonium bromide, CTAB) and a mild reducing agent (ascorbic acid, AA). The effect of varying several reaction parameters (time and CTAB and AA concentrations) was evaluated, showing that more anisotropic particles are obtained at longer reaction times, lower CTAB concentration and higher AA concentration. The final shape of the GNPs was also found to depend on their initial shape and size, as well as the pore size of the mesoporous film covering them. Because the growth proceeds through the pores of the film, it may lead to shapes that are not easily obtained in solution, such as particles with branches on one side only. Finally, we have confirmed that no damage was induced to the mesoporous silica structure during the growth process and thus the final particles remain well covered by the thin film, which can eventually be used as a filter between the GNPs and the outer medium.Fil: Angelomé, Paula C.. Universidad de Vigo; EspañaFil: Pastoriza Santos, Isabel. Universidad de Vigo; EspañaFil: Pérez Juste, Jorge. Universidad de Vigo; EspañaFil: Rodríguez-González, Benito. Universidad de Vigo; EspañaFil: Zelcer, Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; ArgentinaFil: Soler Illia, Galo Juan de Avila Arturo. Universidad de Buenos Aires; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Liz Marzán, Luis M.. Universidad de Vigo; Españ

Detection of rhabdovirus viral RNA in oropharyngeal swabs and ectoparasites of spanish bats

Rhabdoviruses infect a variety of hosts, including mammals, birds, reptiles, fish, insects and plants. As bats are the natural host for most members of the genus Lyssavirus, the specificity of the amplification methods used for active surveillance is usually restricted to lyssaviruses. However, the presence of other rhabdoviruses in bats has also been reported. In order to broaden the scope of such methods, a new RT-PCR, able to detect a diverse range of rhabdoviruses, was designed. The method detected 81 of 86 different rhabdoviruses. In total, 1488 oropharyngeal bat swabs and 38 nycteribiid samples were analysed, and 17 unique rhabdovirus-related sequences were detected. Phylogenetic analysis suggested that those sequences detected in bats did not constitute a monophyletic group, even when originating from the same bat species. However, all of the sequences detected in nycteribiids and one sequence obtained from a bat did constitute a monophyletic group with Drosophila melanogaster sigma rhabdovirus. © 2013 Crown.Peer Reviewe