1,735 research outputs found

    Renormalization Group Equations for the CKM matrix

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    We derive the one loop renormalization group equations for the Cabibbo-Kobayashi-Maskawa matrix for the Standard Model, its two Higgs extension and the minimal supersymmetric extension in a novel way. The derived equations depend only on a subset of the model parameters of the renormalization group equations for the quark Yukawa couplings so the CKM matrix evolution cannot fully test the renormalization group evolution of the quark Yukawa couplings. From the derived equations we obtain the invariant of the renormalization group evolution for three models which is the angle α\alpha of the unitarity triangle. For the special case of the Standard Model and its extensions with v1v2v_{1}\approx v_{2} we demonstrate that also the shape of the unitarity triangle and the Buras-Wolfenstein parameters ρˉ=(11/2λ2)ρ\bar{\rho}=(1-{1/2}\lambda^{2})\rho and ηˉ=(11/2λ2)η\bar{\eta}=(1-{1/2}\lambda^{2})\eta are conserved. The invariance of the angles of the unitarity triangle means that it is not possible to find a model in which the CKM matrix might have a simple, special form at asymptotic energies.Comment: 9 page

    PDB71 CHARACTERISTICS OF EARLY ADOPTERS OF EXPENSIVE MEDICATIONS

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    Digging in the megaproject's graveyard: Why do megaprojects die, and how to check their health?

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    The pressure to complete Infrastructure Megaprojects (IMs) is enormous; once started, IMs are commonly considered too costly to be stopped. Still, despite this widespread belief, several IMs are terminated during delivery/construction. Notwithstanding its empirical and theoretical relevance, few studies investigate IMs termination during delivery/construction. This paper aims to develop further the “reverse escalation of commitment” theory which sense-makes the termination of IMs. We take a critical confrontation of the existing literature addressing two questions: (1) Why are IMs terminated during delivery/construction? and (2) How does the project termination process occur in IMs? By analysing 30 unfinished IMs, we identified the six determinants for IMs termination, contributing to the development of reverse-escalation of commitment theory by providing a processual perspective of the four most common patterns leading to IMs termination. Finally, we provide a checklist for identifying key elements leading to IMs termination

    Sperm mobility: mechanisms of fertilizing efficiency, genetic variation and phenotypic relationship with male status in the domestic fowl, Gallus gallus domesticus

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    When females are sexually promiscuous, sexual selection continues after insemination through sperm competition and cryptic female choice, and male traits conveying an advantage in competitive fertilization are selected for. Although individual male and ejaculate traits are known to influence paternity in a competitive scenario, multiple mechanisms co-occur and interact to determine paternity. The way in which different traits interact with each other and the mechanisms through which their heritability is maintained despite selection remain unresolved. In the promiscuous fowl, paternity is determined by the number of sperm inseminated into a female, which is mediated by male social dominance, and by the quality of the sperm inseminated, measured as sperm mobility. Here we show that: (i) the number of sperm inseminated determines how many sperm reach the female sperm-storage sites, and that sperm mobility mediates the fertilizing efficiency of inseminated sperm, mainly by determining the rate at which sperm are released from the female storage sites, (ii) like social status, sperm mobility is heritable, and (iii) subdominant males are significantly more likely to have higher sperm mobility than dominant males. This study indicates that although the functions of social status and sperm mobility are highly interdependent, the lack of phenotypic integration of these traits may maintain the variability of male fitness and heritability of fertilizing efficiency

    Motility of small nematodes in disordered wet granular media

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    The motility of the worm nematode \textit{Caenorhabditis elegans} is investigated in shallow, wet granular media as a function of particle size dispersity and area density (ϕ\phi). Surprisingly, we find that the nematode's propulsion speed is enhanced by the presence of particles in a fluid and is nearly independent of area density. The undulation speed, often used to differentiate locomotion gaits, is significantly affected by the bulk material properties of wet mono- and polydisperse granular media for ϕ0.55\phi \geq 0.55. This difference is characterized by a change in the nematode's waveform from swimming to crawling in dense polydisperse media \textit{only}. This change highlights the organism's adaptability to subtle differences in local structure and response between monodisperse and polydisperse media

    From cheating to teaching: a path for conversion of illegal gambling machines

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    Video poker machines, a former symbol of fraud and gambling in Brazil, are now being converted into computer-based educational tools for Brazilian public primary schools and also for governmental and non-governmental institutions dealing with communities of poverty and social exclusion, in an attempt to reduce poverty risks (decrease money spent on gambling) and promote social inclusion (increase access and motivation to education). Thousands of illegal gambling machines are seized by federal authorities, in Brazil, every year, and usually destroyed at the end of the criminal apprehension process. This paper describes a project developed by the University of Southern Santa Catarina, Brazil, responsible for the conversion process of gambling machines, and the social inclusion opportunities derived from it. All project members worked on a volunteer basis, seeking to promote social inclusion of Brazilian young boys and girls, namely through digital inclusion. So far, the project has been able to convert over 200 gambling machines and install them in over 40 public primary schools, thus directly benefiting more than 12,000 schoolchildren. The initial motivation behind this project was technology based, however the different options arising from the conversion process of the gambling machines have also motivated a rather innovative and unique experience in allowing schoolchildren and young people with special (educational) needs to access to computer-based pedagogical applications. The availability of these converted machines also helps to place Information and Communication Technologies (ICT) in the very daily educational environment of these children and youngsters, thus serving social and cultural inclusion aspects, by establishing a dialogue with the community and their technological expectations, and also directly contributing to their digital literacy

    Understanding the Clean Interface between Covalent Si and Ionic Al2O3

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    The atomic and electronic structures of the (001)-Si/(001)-gamma-Al2O3 heterointerface are investigated by first principles total energy calculations combined with a newly developed "modified basin-hopping" method. It is found that all interface Si atoms are fourfold coordinated due to the formation of Si-O and unexpected covalent Si-Al bonds in the new abrupt interface model. And the interface has perfect electronic properties in that the unpassivated interface has a large LDA band gap and no gap levels. These results show that it is possible to have clean semiconductor-oxide interfaces

    Remote experimentation: integrating research, education, and industrial application

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    This paper presents a low-cost scaled model of a silo for drying and airing cereal grains. It allows the control and monitor of several parameters associated to the silo's operation, through a remote accessible infrastructure. The scaled model consists of a 2.50 m wide × 2.10 m long plant with all control and monitor capacities provided by micro-Web servers. An application running on the micro-Web servers enables storing all parameters in a data basis for later analysis. The implemented model aims to support a remote experimentation facility for technological education, research-oriented tutorials, and industrial applications. Given the low-cost requirement, this remote facility can be easily replicated in other institutions to support a network of remote labs, which encompasses the concurrent access of several users (e.g. students)

    Study of process parameters on aluminium foam formation in the Al-6Si-3Mg alloy

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    The aim of this research was to study the process parameters that promote foam formation by injecting N2 into Al-6Si-3Mg wt % molten alloy with silicon carbide particles additions (SiC). An experimental design was proposed, in which the contents of SiC particles were 0, 10, 30 and 50 wt %, and the overheating was defined as ΔT= TF - TL , where TL is the liquidus temperature and was determined by the cooling curve method and the foaming temperatures were selected as TF at 630, 610, 580 and 570 °C. Flow and pressure of air blow were constant, 2,0 lt/min and 4,0 atm, respectively. The foam formation was possible only under two experimental conditions, 10 wt % SiC at ΔT > 12 °C and 30 wt % SiC at ΔT > 10 °C. The foams obtained under these conditions were stable, while with other conditions of experiments, bubble coallesence occurred. Finally, it was concluded that the foam formation occurred by SiC contents lower than 30 wt % SiC and temperatures slightly above the liquidus
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