Space-borne global astrometric surveys: the hunt for extra-solar planets

The proposed global astrometry mission {\it GAIA}, recently recommended within the context of ESA's Horizon 2000 Plus long-term scientific program, appears capable of surveying the solar neighborhood within $\sim$ 200 pc for the astrometric signatures of planets around stars down to the magnitude limit of $V$=17 mag, which includes late M dwarfs at 100 pc. Realistic end-to-end simulations of the GAIA global astrometric measurements have yielded first quantitative estimates of the sensitivity to planetary perturbations and of the ability to measure their orbital parameters. Single Jupiter-mass planets around normal solar-type stars appear detectable up to 150 pc ($V\le$12 mag) with probabilities $\ge$ 50 per cent for orbital periods between $\sim$2.5 and $\sim$8 years, and their orbital parameters measured with better than 30 per cent accuracy to about 100 pc. Jupiter-like objects (same mass and period as our giant planet) are found with similar probabilities up to 100 pc.These first experiments indicate that the {\it GAIA} results would constitute an important addition to those which will come from the other ongoing and planned planet-search programs. These data combined would provide a formidable testing ground on which to confront theories of planetary formation and evolution.Comment: 13 pages, 10 figures, uses mn.sty, accepted by MNRA

Error analysis of null space algorithm for linear equality constrained least squares problems

The numerical stability of the null space method for linear least-squares problems with linear equality constraints is studied using a backward error analysis. A class of test problems is also considered in order to show experimentally the behaviour of the method

Surface fitting for extremely large scattered data sets

Given N pairwise distinct and arbitrarily spaced points V_i in a domain of the x-y plane and N real numbers z_i, consider the problem of computing a C1 bivariate function F(x,y) whose values in V_i are exactly z_i. In this paper we present a method for solving the above problem, which is designed for extremely large data sets. A step of this method requires to minimize a quadratic functional; we prove that the hessian matrix is positive definite and is leading a P-regular splitting

The proceedings of the workshop "Numerical Methods in Optimization"

This special issue of Rendiconti del Circolo Matematico di Palermo consists of the lectures presented at the international workshop “Numerical Methods in Oprimization” held at Cortona during June 9-12, 1997.The workshop was organized by INdAM (Istituto Nazionale di Alta Matematica “Francesco Severi”) and partially supported by GNIM (Gruppo Nazionale per l’Informatica Matematica – CNR), CPS (Research Center on Parallel Computing and Supercomputers) and by EEC (HCMR Grant n. ERBCHECCT940253).The purpose of the workshop was to bring together mathematicians working in areas of Optimization where numerical methods play a basic role, so that they could not only present formal lectures, but also exchange ideas informally.The papers in this issue are arranged in alphabetic order of their authors’ name.Some papers deal with the solution to particular problems while others are devoted primarily to theoretical and numerical aspects of optimization. However, these latter papers also contain some problems of practical interest.This special issue of the journal Rendiconti del Circolo Matematico di Palermo allows a scientific continuity with the issue Serie II, Suppl. Volume 48, 1997 (edited by F. Giannessi, A. Maugeri and M. De Luca) containing the proceedings of the international worksop “Equilibrium Problems with Side Constraints, Lagrangean Theory and Duality II” held in Scilla, May 17-18, 1996

Upper limb disability in hemodialysis patients: evaluation of contributing factors aside from amyloidosis.

This cross-sectional case-control study evaluated upper limb muscle strength and shoulder mobility in hemodialysis (HD) patients with arteriovenous fistula or graft. Twenty-five adult patients on thrice-a-week HD treatment for 6 months at least, were selected for the study. In all the patients and control subjects, handgrip tests and tests of range of motion in the upper extremities were evaluated by physiotherapy tests. Patients on HD showed lower muscle strength than age and sex matched subjects without severe chronic kidney disease (right: 30.1 ± 11.6 vs 40.5 ± 15.1 kg, P < 0.001; left 29.1 ± 12.9 vs 40.7 ± 11.1 kg, P < 0.01), and a reduced range of shoulder mobility. The presence of fistula or graft was associated with a greater limitation of both active (74.0 ± 18.3 vs 85.2 ± 8.8 °, P < 0.01) and passive (82.2 ± 9.9 vs 87.2 ± 6.6 °, P < 0.05) extra-rotation than the contralateral limb, with a higher prevalence of impingement (72 vs 36%, P < 0.05). Muscle strength was related to albumin and inversely to age; whereas β(2) -microglobulin and CRP serum levels were associated with impairment of passive and active extra-rotation of the shoulder that was free from the fistula or graft. In summary, patients on HD have a reduced range of shoulder mobility and marked reduction of muscle strength. The abnormalities are more prevalent in upper limbs with fistula or grafts. The arteriovenous fistula or graft may worsen the disability of the patient's upper limbs presumably due to the obligate position required during the HD sessions. Proper pre- and post-dialysis exercise programs should be implemented to maintain mobility and strength of the upper limbs

Further characterisation of differences between TL and AB zebrafish (Danio rerio): gene expression, physiology and behaviour at day 5 of the larval stage

Contains fulltext : 175469.pdf (publisher's version ) (Open Access)15 p

Su e di Ludovico Quaroni. 7 interviste su 7 libri

Video realizzato in occasione della mostra su Ludovico Quaroni che si è tenuta al Museo Laboratorio d'Arte Contemporanea dell'Università di Roma La Sapienza il 29/30/31 ottobre 2003. La mostra accompagnava il convegno La Città Meravigliosa di Ludovico Quaroni, coordinatore Antonino Terranov