Precise nondivergent analytic formulas for the radiative corrections to the beta energy spectrum in hyperon semileptonic decays over the entire Dalitz plot

Very accurate analytical expressions for the radiative corrections of unpolarized hyperons semileptonic decays of charged and neutral baryons have been obtained in the recent past. Some of these formulas contain logarithmic singularities at the edges of the Dalitz plot for the three- and four-body decays. These singularities are analyzed and integrated analytically to obtain new divergentless formulas for the energy spectrum of the produced beta particle. The new equations contain terms of the order alpha times the momentum transfer, are applicable to any beta decay process and are suitable for a model-independent experimental analysis.Comment: 22 pages, 4 figure

Precise bounds on the Higgs boson mass

We study the renormalization group evolution of the Higgs quartic coupling $\lambda_{H}$ and the Higgs mass $m_{H}$ in the Standard Model. The one loop equation for $\lambda_{H}$ is non linear and it is of the Riccati type which we numerically and analytically solve in the energy range $[m_{t},E_{GU}]$ where $m_{t}$ is the mass of the top quark and $E_{GU}=10^{14}$ GeV. We find that depending on the value of $\lambda_{H}(m_{t})$ the solution for $\lambda_{H}(E)$ may have singularities or zeros and become negative in the former energy range so the ultra violet cut off of the standard model should be below the energy where the zero or singularity of $\lambda_{H}$ occurs. We find that for $0.369\leq\lambda_{H}(m_{t})\leq0.613$ the Standard Model is valid in the whole range $[m_{t},E_{GU}]$. We consider two cases of the Higgs mass relation to the parameters of the standard model: (a) the effective potential method and (b) the tree level mass relations. The limits for $\lambda_{H}(m_{t})$ correspond to the following Higgs mass relation $150\leq m_{H}\lessapprox 193$ GeV. We also plot the dependence of the ultra violet cut off on the value of the Higgs mass. We analyze the evolution of the vacuum expectation value of the Higgs field and show that it depends on the value of the Higgs mass. The pattern of the energy behavior of the VEV is different for the cases (a) and (b). The behavior of $\lambda_{H}(E)$, $m_{H}(E)$ and $v(E)$ indicates the existence of a phase transition in the standard model. For the effective potential this phase transition occurs at the mass range $m_{H}\approx 180$ GeV and for the tree level mass relations at $m_{H}\approx 168$ GeV.Comment: 14 pages, 7 figures. Expanded the discussion of the Higgs mass relation between the parameters of the Standard Model. Included the method of the Higgs effective potentia

Scale dependence of the quark masses and mixings: leading order

We consider the Renormalization Group Equations (RGE) for the couplings of the Standard Model and its extensions. Using the hierarchy of the quark masses and of the Cabibbo-Kobayashi-Maskawa (CKM) matrix our argument is that a consistent approximation for the RGE should be based on the parameter $\lambda= |\hat{V}_{ud}| \approx0.22$. We consider the RGE in the approximation where we neglect all the relative terms of the order $\sim\lambda^{4}$ and higher. Within this approximation we find the exact solution of the evolution equations of the quark Yukawa couplings and of the vacuum expectation value of the Higgs field. Then we derive the evolution of the observables: quark masses, CKM matrix, Jarlskog invariant, Wolfenstein parameters of the CKM matrix and the unitarity triangle. We show that the angles of the unitarity triangle remain constant. This property may restrict the possibility of new symmetries or textures at the grand unification scale.Comment: 15 pages, 4 figures, author of one reference adde

Use of Individual-Level Covariates to Improve Latent Class Analysis of Trypanosoma Cruzi Diagnostic Tests

Statistical methods such as latent class analysis can estimate the sensitivity and specificity of diagnostic tests when no perfect reference test exists. Traditional latent class methods assume a constant disease prevalence in one or more tested populations. When the risk of disease varies in a known way, these models fail to take advantage of additional information that can be obtained by measuring risk factors at the level of the individual. We show that by incorporating complex field-based epidemiologic data, in which the disease prevalence varies as a continuous function of individual-level covariates, our model produces more accurate sensitivity and specificity estimates than previous methods. We apply this technique to several simulated populations and to actual Chagas disease test data from a community near Arequipa, Peru. Results from our model estimate that the first-line enzyme-linked immunosorbent assay has a sensitivity of 78% (95% CI: 62-100%) and a specificity of 100% (95% CI: 99-100%). The confirmatory immunofluorescence assay is estimated to be 73% sensitive (95% CI: 65-81%) and 99% specific (95% CI: 96-100%)

Control of Pyrethroid-Resistant Chagas Disease Vectors with Entomopathogenic Fungi

Chagas disease, also known as American Trypanosomiasis, is the most relevant parasitic disease in Latin America, being a major burden that affects mostly poor human populations living in rural areas. The kissing-bugs of the Triatominae family transmit the parasite Trypanosoma cruzi by infectious blood-sucking; Triatoma infestans is the vector of major relevance in the southern Cone of South America. Current control strategies, heavily based on residual insecticide spraying, are threatened by the emergence of pyrethroid-resistant bug populations. Furthermore, ensuring the long-term and sustainable control of this overwhelming disease remains a major challenge. Here we show the utility of a simple, low-cost, biological control methodology against T. infestans bugs, regardless of their susceptibility to pyrethroid insecticides. It is based on the understanding of the initial contact interactions between a mycoinsecticide agent—the fungus Beauveria bassiana—and the host defense barrier, the bug cuticle. The proposed methodology is also supported by present data showing a relationship between the triatomine cuticle width and its hydrocarbon surface components, with insecticide resistance. These results will help to provide a safe and efficient alternative to overcome pyrethroid-resilience of these noxious bugs. A high transfer potential to immediate application in rural communities located in remote areas inaccessible to sanitary control teams, and to the control of other Chagas disease vectors as well, is also envisaged

Robust Estimators in Generalized Pareto Models

This paper deals with optimally-robust parameter estimation in generalized Pareto distributions (GPDs). These arise naturally in many situations where one is interested in the behavior of extreme events as motivated by the Pickands-Balkema-de Haan extreme value theorem (PBHT). The application we have in mind is calculation of the regulatory capital required by Basel II for a bank to cover operational risk. In this context the tail behavior of the underlying distribution is crucial. This is where extreme value theory enters, suggesting to estimate these high quantiles parameterically using, e.g. GPDs. Robust statistics in this context offers procedures bounding the influence of single observations, so provides reliable inference in the presence of moderate deviations from the distributional model assumptions, respectively from the mechanisms underlying the PBHT.Comment: 26pages, 6 figure

3D characterization of CdSe nanoparticles attached to carbon nanotubes

The crystallographic structure of CdSe nanoparticles attached to carbon nanotubes has been elucidated by means of high resolution transmission electron microscopy and high angle annular dark field scanning transmission electron microscopy tomography. CdSe rod-like nanoparticles, grown in solution together with carbon nanotubes, undergo a morphological transformation and become attached to the carbon surface. Electron tomography reveals that the nanoparticles are hexagonal-based with the (001) planes epitaxially matched to the outer graphene layer.Comment: 7 pages, 8 figure

Generally covariant dynamical reduction models and the Hadamard condition

We recall and review earlier work on dynamical reduction models, both non-relativistic and relativistic, and discuss how they may relate to suggestions which have been made (including the matter-gravity entanglement hypothesis of one of us) for how quantum gravity could be connected to the resolution of the quantum-mechanical measurement problem. We then provide general guidelines for generalizing dynamical reduction models to curved spacetimes and propose a class of generally covariant relativistic versions of the GRW model. We anticipate that the collapse operators of our class of models may play a r\^ole in a yet-to-be-formulated theory of semiclassical gravity with collapses. We show explicitly that the collapse operators map a dense domain of states that are initially Hadamard to final Hadamard states -- a property that we expect will be needed for the construction of such a semiclassical theory. Finally, we provide a simple example in which we explicitly compute the violations in energy-momentum due to the state reduction process and conclude that this violation is of the order of a parameter of the model -- supposed to be small. We briefly discuss how this work may, upon further development of a suitable semiclassical gravity theory with collapses, enable further progress to be made on earlier work one of us and collaborators on the explanation of structure-formation in a homogeneous and isotropic quantum universe and on a possible resolution of the black hole information loss puzzle

Multiple glass transitions in star polymer mixtures: Insights from theory and simulations

The glass transition in binary mixtures of star polymers is studied by mode coupling theory and extensive molecular dynamics computer simulations. In particular, we have explored vitrification in the parameter space of size asymmetry $\delta$ and concentration $\rho_2$ of the small star polymers at fixed concentration of the large ones. Depending on the choice of parameters, three different glassy states are identified: a single glass of big polymers at low $\delta$ and low $\rho_2$, a double glass at high $\delta$ and low $\rho_2$, and a novel double glass at high $\rho_2$ and high $\delta$ which is characterized by a strong localization of the small particles. At low $\delta$ and high $\rho_2$ there is a competition between vitrification and phase separation. Centered in the $(\delta, \rho_2)$-plane, a liquid lake shows up revealing reentrant glass formation. We compare the behavior of the dynamical density correlators with the predictions of the theory and find remarkable agreement between the two.Comment: 15 figures, to be published in Macromolecule