Constraints on the parameters of the CKM matrix by End 1998

A review of the current status of the Cabibbo-Kobayashi-Maskawa matrix (CKM) is presented. This paper is an update of the results published in [1]. The experimental constraints imposed by the measurements of \epsilon_K, V_{ub}/V_{cb}, \Delta m_d and from the limit on \Delta m_d are used. Values of the constraints and of the parameters entering into the constraints, which restrict the range of the \bar{\rho} and \bar{\eta} parameters, include recent measurements presented at 1998 Summer Conferences and progress obtained by lattice QCD collaborations. The results are: \bar{\rho}=0.202 ^{+0.053}_{-0.059},\bar{\eta}=0.340 \pm 0.035, from which the angles \alpha, \beta and \gamma of the unitarity triangle are inferred : \sin 2 \alpha = -0.26 ^{+ 0.29}_{-0.28} ,\sin 2 \beta = 0.725 ^{+0.050}_{-0.060} ,\gamma= (59.5^{+8.5}_{-7.5})^{\circ}. Without using the constraint from \epsilon_K, \sin 2 \beta has been obtained: \sin 2 \beta = 0.72 ^{+0.07}_{-0.11}. Several external measurements or theoretical inputs have been removed, in turn, from the constraints and their respective probability density functions have been obtained. Central values and uncertainties on these quantities have been compared with actual measurements or theoretical evaluations. In this way it is possible to quantify the importance of the different measurements and the coherence of the Standard Model scenario for CP violation. An important result is that \Delta m_s is expected to be between [12.0-17.6] ps^{-1} with 68% C.L. and <20 ps^{-1} at 95% C.L. Finally relations between the CKM parameters and the quark masses are examined within a given model.Comment: 26 page

Strong gravitational field light deflection in binary systems containing a collapsed star

Large light deflection angles are produced in the strong gravitational field regions around neutron stars and black holes. In the case of binary systems, part of the photons emitted from the companion star towards the collapsed object are expected to be deflected in the direction of the earth. Based on a semi-classical approach we calculate the characteristic time delays and frequency shifts of these photons as a function of the binary orbital phase. The intensity of the strongly deflected light rays is reduced by many orders of magnitude, therefore making the observations of this phenomenon extremely difficult. Relativistic binary systems containing a radio pulsar and a collapsed object are the best available candidates for the detection of the strongly deflected photons. Based on the accurate knowledge of their orbital parameters, these systems allow to predict accurately the delays of the pulses along the highly deflected path, such that the sensitivity to very weak signals can be substantially improved through coherent summation over long time intervals. We discuss in detail the cases of PSR 1913+16 and PSR 1534+12 and find that the system geometry is far more promising for the latter. The observation of the highly deflected photons can provide a test of general relativity in an unprecedented strong field regime as well as a tight constraint on the radius of the collapsed object.Comment: 7 pages, uuencoded, gzip'ed, postscript file with figures included. Accepted for pubblication in MNRA

A detector of gravitational waves based on coupled microwave cavities

Since 1978 superconducting coupled cavities have been proposed as sensitive detector of gravitational waves. The interaction of the gravitational wave with the cavity walls, and the resulting motion, induces the transition of some electromagnetic energy from an initially excited cavity mode to an empty one. The energy transfer is maximum when the frequency of the wave is equal to the frequency difference of the two cavity modes. In this paper the basic principles of the detector are discussed. The interaction of a gravitational wave with the cavity walls is studied in the proper reference frame of the detector, and the coupling between two electromagnetic normal modes induced by the wall motion is analyzed in detail. Noise sources are also considered; in particular the noise coming from the brownian motion of the cavity walls is analyzed. Some ideas for the developement of a realistic detector of gravitational waves are discussed; the outline of a possible detector design and its expected sensitivity are also shown.Comment: 29 pages, 12 eps figures. Typeset by REVTe

Parametric gravity wave detector

Since 1978 superconducting coupled cavities have been proposed as a sensitive detector of gravitational waves. The interaction of the gravitational wave with the cavity walls, and the esulting motion, induces the transition of some energy from an initially excited cavity mode to an empty one. The energy transfer is maximum when the frequency of the wave is equal to the frequency difference of the two cavity modes. In 1984 Reece, Reiner and Melissinos built a detector of the type proposed, and used it as a transducer of harmonic mechanical motion, achieving a sensitivity to fractional deformations of the order dx/x ~ 10^(-18). In this paper the working principles of the detector are discussed and the last experimental results summarized. New ideas for the development of a realistic gravitational waves detector are considered; the outline of a possible detector design and its expected sensitivity are also shown.Comment: 9 pages, 6 figures. Talk given at the Workshop on Electromagnetic Probes of Fundamentals Physics, Erice (Italy), October 200

The Endoplasmic Reticulum Glucosyltransferase Recognizes Nearly Native Glycoprotein Folding Intermediates

The UDP-Glc:glycoprotein glucosyltransferase (GT), a key player in the endoplasmic reticulum (ER) quality control of glycoprotein folding, only glucosylates glycoproteins displaying non-native conformations. To determine whether GT recognizes folding intermediates or irreparably misfolded species with nearly native structures, we generated and tested as GT substrates neoglycoprotein fragments derived from chymotrypsin inhibitor 2 (GCI2) bearing from 53 to 64 (full-length) amino acids. Fragment conformations mimicked the last stage-folding structures adopted by a glycoprotein entering the ER lumen. GT catalytic efficiency (V(max)/K(m)) remained constant from GCI2-(1-53) to GCI2-(1-58) and then steadily declined to reach a minimal value with GCI2-(1-64). The same parameter showed a direct hyperbolic relationship with solvent accessibility of the single Trp residue but only in fragments exposing hydrophobic amino acid patches. Mutations introduced (GCI2-(1-63)V63S and GCI2-(1-64)V63S) produced slight structural destabilizations but increased GT catalytic efficiency. This parameter presented an inverse exponential relationship with the free energy of unfolding of canonical and mutant fragments. Moreover, the catalytic efficiency showed a linear relationship with the fraction of unfolded species in water. It was concluded that the GT-derived quality control may be operative with nearly native conformers and that no alternative ER-retaining mechanisms are required when glycoproteins approach their proper folding.Fil: Caramelo, Julio Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Castro, Olga Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: de Prat Gay, Gonzalo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Parodi, Armando José A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentin

Dynamics of intense convective rain cells

International audienceIntense precipitation events are often convective in nature. A deeper understanding of the properties and the dynamics of convective rain cells is, therefore, necessary both from a physical and operational point of view. The aim of this work is to study the spatial-temporal properties of convective rain cells by using a fully parameterized nonhydrostatic code (Lokal Model) in simplified model configurations. High resolution simulations are performed and it is expected that the deep moist convection and the feedback mechanisms affecting larger scales of motion can then be resolved explicitly and some of the critical constraints of parameterization schemes can be relaxed. The sensitivity of the spatio-temporal properties of simulated cells to spatial resolution and microphysics schemes is investigated and discussed through a direct comparison with typical intense convective cells measured by radars

An operational flash-flood forecasting chain applied to the test cases of the EU project HYDROPTIMET

International audience The application of a flash-flood prediction chain, developed by CIMA, to some testcases for the Tanaro river basin in the framework of the EU project HYDROPTIMET is presented here. The components of the CIMA chain are: forecast rainfall depths, a stochastic downscaling procedure and a hydrological model. Different meteorological Limited Area Models (LAMs) provide the rainfall input to the hydrological component. The flash-flood prediction chain is run both in a deterministic and in a probabilistic configuration. The sensitivity of forecasting chain performances to different LAMs providing rainfall forecasts is discussed. The results of the application show how the probabilistic forecasting system can give, especially in the case of convective events, a valuable contribution in addressing the uncertainty at different spatio-temporal scales involved in the flash flood forecasting problem in small and medium basins with complex orography

Effect of Vapor-Liquid Equilibrium Data on the Design of Separation Sequences by Distillation

An evaluation of the effect of vapor-liquid equilibrium experimental data on the design of separation sequences by distillation was done using computer simulation. Separation of a mixture of ace-tone-chloroform-benzene was chosen as an example problem. Two sequences were compared. To quantify the thermodynamic data uncertainties for each se-quence two sets of binary vapor-liquid equilibrium data were chosen. These two sets of data were used to generate simulation cases as in classical two-level fac-torial design of experiments. A third set of binary va-por-liquid experimental data allows comparing phase liquid models. For the two-column sequence, analysis done to each column alone or to the whole sequence gave the same results. In the three-column sequence, results were different and simulation of the whole se-quence gave a complete different account that simula-tion of each column alone.Fil: Parodi, C. A.. Universidad Nacional del Litoral; ArgentinaFil: Campanella, Enrique Angel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin