Periodic boxcar deconvolution and diophantine approximation

We consider the nonparametric estimation of a periodic function that is observed in additive Gaussian white noise after convolution with a ``boxcar,'' the indicator function of an interval. This is an idealized model for the problem of recovery of noisy signals and images observed with ``motion blur.'' If the length of the boxcar is rational, then certain frequencies are irretreviably lost in the periodic model. We consider the rate of convergence of estimators when the length of the boxcar is irrational, using classical results on approximation of irrationals by continued fractions. A basic question of interest is whether the minimax rate of convergence is slower than for nonperiodic problems with 1/f-like convolution filters. The answer turns out to depend on the type and smoothness of functions being estimated in a manner not seen with ``homogeneous'' filters.Comment: Published at http://dx.doi.org/10.1214/009053604000000391 in the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Surface Brightness Fluctuations: a theoretical point of view

We present new theoretical evaluations of optical and near-IR Surface Brightness Fluctuations (SBF) magnitudes for single-burst stellar populations in the age range t=5-15 Gyr and metallicity from Z_{\sun}/200 to 2Z_{\sun}. Our theoretical predictions can be successfully used to derive reliable distance evaluations. They also appear to be a new and valuable tool to trace the properties of unresolved stellar populations.Comment: 2 pages, incl. 1 figure, uses newpasp.sty, to be published in ``New Horizons in Globular Cluster Astronomy'', ASP Conference Series, 2002; Eds.: G. Piotto, G. Meylan, G. Djorgowski and M. Riello, in pres

New floristic data of alien vascular plants from Sicily

New records of Commelina communis, Euphorbia hypericifolia, Melia azedarach, Nicotiana tabacum, and Xanthoceras sorbifolium are reported for the Sicilian flora

Predicted HST FOC and broad band colours for young and intermediate Simple Stellar Populations

This paper presents theoretical HST and broad band colours from population synthesis models based on an homogeneous set of stellar evolutionary tracks as computed under canonical (no overshooting) assumptions, covering the range of cluster ages from t=8 Myr to t=5 Gyr for three different metallicities (Z=0.02, 0.006, and 0.001). Statistical fluctuations in the cluster population have been investigated, assessing the predicted fluctuations of the various colours as a function of the cluster integrated absolute magnitude. We show that the red leak in HST UV filters deeply affects the predicted fluxes and colours. However, we find that for F152M-F307M < 0.5 and for F170M-F278M < 0.5 (which means ages lower than 1 Gyr) the HST UV colours can still be used to infer reliable indications on the age of distant clusters. Moreover, one finds that the age calibration of these colours is scarcely affected by the amount of original helium or by the assumed IMF. On this basis, we present a calibration of the HST UV two-colours (F152M-F307M vs F170M-F278M) in terms of cluster ages for the three above quoted metallicities. We suggest the combined use of HST UV colours and IR colours (V-K in particular) to disentangle the metallicity-age effect in integrated colours of young stellar populations (t< 1 Gyr).Comment: Latex 18 pages, 16 encapsulated figures, 6 tables, A&ASS accepte

Incomplete markets with no Hart points

We provide a geometric test of whether a general equilibrium incomplete markets (GEI) economy has Hart points---points at which the rank of the securities payoff matrix drops. Condition (H) says that, at each nonterminal node, there is an affine set (of appropriate dimension) that intersects all of a well-specified set of convex polyhedra. If the economy has Hart points, then Condition (H) is satisfied; consequently, if condition (H) fails, the economy has no Hart points. The shapes of the convex polyhedra are determined by the number of physical goods and the dividends of the securities, but are independent of the endowments and preferences of the agents. Condition (H) fails, and thus there are no Hart points, in interesting classes of economies with only short-lived securities, including economies obtained by discretizing an economy with a continuum of states and sufficiently diverse payoffs.Incomplete Markets, GEI model, Hart points

On the impact of Helium abundance on the Cepheid Period-Luminosity and Wesenheit relations and the Distance Ladder

This work analyses the effect of the Helium content on synthetic Period-Luminosity Relations (PLRs) and Period-Wesenheit Relations (PWRs) of Cepheids and the systematic uncertainties on the derived distances that a hidden population of He-enhanced Cepheids may generate. We use new stellar and pulsation models to build a homogeneous and consistent framework to derive the Cepheid features. The Cepheid populations expected in synthetic color-magnitude diagrams of young stellar systems (from 20 Myr to 250 Myr) are computed in several photometric bands for Y = 0.25 and Y = 0.35, at a fixed metallicity (Z = 0.008). The PLRs appear to be very similar in the two cases, with negligible effects (few %) on distances, while PWRs differ somewhat, with systematic uncertainties in deriving distances as high as about 7% at log P < 1.5. Statistical effects due to the number of variables used to determine the relations contribute to a distance systematic error of the order of few percent, with values decreasing from optical to near-infrared bands. The empirical PWRs derived from multi-wavelength datasets for the Large Magellanic Cloud (LMC) is in a very good agreement with our theoretical PWRs obtained with a standard He content, supporting the evidence that LMC Cepheids do not show any He effect

Natura e architettura nel giardino di Villa Florio-Pignatelli (Palermo, Sicilia).

ABSTRACT.\u2013 Amongst the Sicilian historical gardens it is merited to remember the ornamental garden design of Villa Florio- Pignatelli, situated in the western periphery of Palermo. The building, and probably the garden too, are from the second half of the 18. century. This article contains the result of a cognitive study of its history, architecture and vegetal composition, based on field studies in the garden itself, on bibliographical and archival work. In 1838 it was sold by the Duke of Cumia to Vincenzo Florio, who in following conceded it to his son Ignazio. Already at this time, there was a garden with a "flora all\u2019Italiana" behind the Villa, which had circular vials in radial order, demarcated with a box-hedge (Buxus sempervirens), much like a small reproduction of the more famous and celebrated Villa Giulia (1777), the first public garden in the town.The elegance of the garden's proportions is based on at least four geometric orders interacting with each other. They reveal evi- dence of important fixed points or "topoi" of the garden; these affirm that the apparent simplicity contains complicated arith- metic and geometric relations in an exceptional union of architectural and botanical significance

Multipopulation aftereffects on the color-magnitude diagram and Cepheid variables of young stellar systems

Context: The evidence of a multipopulation scenario in Galactic globular clusters raises several questions about the formation and evolution of the two (or more) generations of stars. These populations show differences in their age and chemical composition. These differences are found in old- and intermediate- age stellar clusters in the Local Group. The observations of young stellar systems are expected to present footprints of multiple stellar populations. Aims: This theoretical work intends to be a specific step in exploring the space of the observational indicators of multipopulations, without covering all the combinations of parameters that may contribute to the formation of multiple generations of stars in a cluster or in galaxy. The goal is to shed light on the possible observational features expected by core He-burning stars that belong to two stellar populations with different original He content and ages. Methods: The tool adopted was the stellar population synthesis. We used new stellar and pulsation models to construct a homogeneous and consistent framework. Synthetic color-magnitude diagrams (CMDs) of young- and intermediate-age stellar systems (from 20 Myr up to 1 Gyr) were computed in several photometric bands to derive possible indicators of double populations both in the observed CMDs and in the pulsation properties of the Cepheids. Results: We predict that the morphology of the red/blue clump in VIK bands can be used to photometrically indicate the two stellar populations in a rich assembly of stars if there is a significant difference in their original He content. Moreover, the period distribution of the Cepheids appears to be widely affected by the coeval multiple generations of stars within stellar systems. We show that the Wesenheit relations may be affected by the helium content of the Cepheids.Comment: in press on A&

Global Sensitivity Methods for Design of Experiments in Lithium-ion Battery Context

Battery management systems may rely on mathematical models to provide higher performance than standard charging protocols. Electrochemical models allow us to capture the phenomena occurring inside a lithium-ion cell and therefore, could be the best model choice. However, to be of practical value, they require reliable model parameters. Uncertainty quantification and optimal experimental design concepts are essential tools for identifying systems and estimating parameters precisely. Approximation errors in uncertainty quantification result in sub-optimal experimental designs and consequently, less-informative data, and higher parameter unreliability. In this work, we propose a highly efficient design of experiment method based on global parameter sensitivities. This novel concept is applied to the single-particle model with electrolyte and thermal dynamics (SPMeT), a well-known electrochemical model for lithium-ion cells. The proposed method avoids the simplifying assumption of output-parameter linearization (i.e., local parameter sensitivities) used in conventional Fisher information matrix-based experimental design strategies. Thus, the optimized current input profile results in experimental data of higher information content and in turn, in more precise parameter estimates.Comment: Accepted for 21st IFAC World Congres