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

Unitarity Triangle Analysis in the Standard Model and Sensitivity to New Physics

By using the most recent determinations of the several theoretical and experimental input parameters, we update the Unitarity Triangle analysis in the Standard Model and discuss the sensitivity to New Physics effects. We investigate the interest of measuring with a better precision the various physical quantities entering the Unitarity Triangle analysis and study in a model independent way whether, despite the undoubted success of the CKM mechanism in the Standard Model, the Unitarity Triangle analysis still allows the presence of New Physics.Comment: Invited talk at the Workshop on the CKM Unitarity Triangle, IPPP Durham, April 2003 (eConf C0304052). 9 pages LaTeX, 15 eps figures. Misprint corrected and references adde

Hemoglobin life-threatening value (1.9 g/dl) in good general condition: a pediatric case-report

Abstract Background We report a pediatric patient presenting in good general condition despite a hemoglobin value of 1,9 g/dL, which is normally regarded as life-threatening. Case presentation An African 5 years-old girl presented to our Emergency Department (ED) for worsening asthenia, within a clinical picture of good general condition. The hemoglobin value at admission was 1,9 g/dL. The subsequent diagnostic-therapeutic pathway highlighted the presence of two different causes, both well known to be responsible for chronic anemia (with slow reduction of hemoglobin values): iron deficiency anemia (IDA) due to a very low dietary intake of iron-rich foods, and homozygous sickle cell disease (HbSS). She received transfusions of packed red blood cells (overall 15 ml/kg) and subsequently intravenous iron preparations (total amount 200 mg) followed by oral iron supplements. The Hb value at discharge, 10 days after the admission, was 9.8 g/dL. Conclusions When approaching a picture of severe anemia, we suggest pediatricians take into consideration clinical conditions rather than laboratory values and to take advantage of detailed anamnestic data in order to make the diagnosis

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XPS characterization of niobium for RF cavities

none4A. Daccà; G. Gemme; L. Mattera; R. ParodiA., Daccà; G., Gemme; Mattera, Lorenzo; R., Parod

Assessing uncertainty in radar measurements on simplified meteorological scenarios

A three-dimensional radar simulator model (RSM) developed by Haase (1998) is coupled with the nonhydrostatic mesoscale weather forecast model Lokal-Modell (LM). The radar simulator is able to model reflectivity measurements by using the following meteorological fields, generated by Lokal Modell, as inputs: temperature, pressure, water vapour content, cloud water content, cloud ice content, rain sedimentation flux and snow sedimentation flux. This work focuses on the assessment of some uncertainty sources associated with radar measurements: </p><ol> <li>absorption by the atmospheric gases, e.g., molecular oxygen, water vapour, and nitrogen; </li> <li>attenuation due to the presence of a highly reflecting structure between the radar and a &quot;target structure&quot;. </li> </ol> RSM results for a simplified meteorological scenario, consisting of a humid updraft on a flat surface and four cells placed around it, are presented

A probabilistic framework to define the design stress and acceptable defects under combined-cycle fatigue conditions

Abstract Probabilistic routines are necessary to determine the permissible design stress when the operational conditions of traditional gas turbines are further challenged to reach higher performances in terms of flexibility. This paper focuses on the definition of a probabilistic tool aimed to simulate the damage development under combined high and low cycle fatigue conditions considering the stochastic nature of some of the variables introduced in the model. The variables considered in the present study are the long crack threshold Δ K th , LC and the slope of the crack growth law C in the so-called Paris region, the endurance limit Δ σ w 0 and the variability of the applied stress as it cannot be considered a fixed variable in the complex loading scenario of gas turbines. A broad experimental campaign was performed to characterize the material properties in terms of short and long crack resistance under constant and combined cyclic conditions. The data were used to define the average and variance of the materials parameters to feed Montecarlo simulations and, at a target probability of failure, establish the design stress. This work points to determine safety margins which strictly depend on the natural variability of the variables that govern the damage accumulation in the mechanical component