Modellazione Geometrica con MD-Spline

Le curve B-spline comunemente usate in modellazione geometrica sono costituite da segmenti polinomiali aventi tutti lo stesso grado. Nella pratica, è spesso necessario modellare curve composte da segmenti polinomiali di grado differente. In questi casi l’utilizzo delle curve B-spline classiche complica inutilmente la modellazione ed necessita di informazioni superflue alla descrizione matematica della curva. Le curve MD-Spline (Multi Degree Spline) sono una generalizzazione delle curve B-spline costituite da segmenti polinomiali di gradi differenti. Con le MD-Spline un progettista CAD ha la possibilità di gestire il grado di ogni segmento in maniera indipendente dagli altri e può rappresentare una determinata forma specificando solo le informazioni strettamente necessarie a definirla. La conseguenza è che modellare con curve MD-Spline si rivela più semplice e rapido rispetto a quanto possibile con curve B-spline. La tesi tratta le MD-Spline descrivendone gli aspetti teorici alla base ed i principali algoritmi di modellazione. In particolare il lavoro di tesi ha prodotto il primo software di modellazione con curve MD-Spline

Supernova Classes and Subclasses

The discovery of many objects with unprecedented, amazing observational characteristics caused the last decade to be the most prolific period for the supernova research. Many of these new supernovae are transitional objects between existing classes, others well enter within the defined classes, but still show unique properties. This makes the traditional classification scheme inadequate to take into account the overall SN variety and, consequently, requires the introduction of new subclasses.Comment: 10 pages, 2 figure, review for "Supernova 1987A: 20 Years After: Supernovae and Gamma-Ray Bursters" AIP, New York, eds. S. Immler, K.W. Weiler, and R. McCra

Dark Matter in Fractional Gravity I: Astrophysical Tests on Galactic Scales

[abridged] We explore the possibility that the dark matter (DM) component in galaxies may originate fractional gravity. In such a framework, the standard law of inertia continues to hold, but the gravitational potential associated to a given DM density distribution is determined by a modified Poisson equation including fractional derivatives (i.e., derivatives of non-integer type), that are meant to describe non-local effects. We derive analytically the expression of the potential that in fractional gravity corresponds to various spherically symmetric density profiles, including the Navarro-Frenk-White (NFW) distribution that is usually exploited to describe virialized halos of collisionless DM as extracted from $N-$body cosmological simulations. We show that in fractional gravity the dynamics of a test particle moving in a cuspy NFW density distribution is substantially altered with respect to the Newtonian case (i.e., basing on the standard Poisson equation), mirroring what in Newtonian gravity would instead be sourced by a density profile with an inner core. We test the fractional gravity framework on galactic scales, showing that: (i) it can provide accurate fits to the stacked rotation curves of galaxies with different properties; (ii) it can reproduce to reasonable accuracy the observed shape and scatter of the radial acceleration relation (RAR); (iii) it can properly account for the universal surface density and the core radius vs. disk scale-length scaling relations. Finally, we discuss the possible origin of the fractional gravity behavior as a fundamental or emerging property of the elusive DM component.Comment: 30 pages, 11 figures, Accepted by Ap

Pulmonary adenocarcinomas presenting as ground-glass opacities on multidetector CT: three-dimensional computer-assisted analysis of growth pattern and doubling time

We aimed to evaluate the growth pattern and doubling time (DT) of pulmonary adenocarcinomas exhibiting ground-glass opacities (GGOs) on multidetector computed tomography (CT). METHODS The growth pattern and DT of 22 pulmonary adenocarcinomas exhibiting GGOs were retrospectively analyzed using three-dimensional semiautomatic software. Analysis of each lesion was based on calculations of volume and mass changes and their respective DTs throughout CT follow- up. Three-dimensional segmentation was performed by a single radiologist on each CT scan. The same observer and another radiologist independently repeated the segmentation at the baseline and the last CT scan to determine the variability of the measurements. The relationships among DTs, histopathology, and initial CT features of the lesions were also analyzed. RESULTS Pulmonary adenocarcinomas presenting as GGOs exhibited different growth patterns: some lesions grew rapidly and some grew slowly, whereas others alternated between periods of growth, stability, or shrinkage. A significant increase in volume and mass that exceeded the coefficient of repeatability of interobserver variability was observed in 72.7% and 84.2% of GGOs, respectively. The volume-DTs and mass-DTs were heterogeneous throughout the follow-up CT scan (range, -4293 to 21928 and -3113 to 17020 days, respectively), and their intra- and interobserver variabilities were moderately high. The volume-DTs and mass-DTs were not correlated with the initial CT features of GGOs; however, they were significantly shorter in invasive adenocarcinomas (P = 0.002 and P = 0.001, respectively). CONCLUSION Pulmonary adenocarcinomas exhibiting GGOs show heterogeneous growth patterns with a trend toward a progressive increase in size. DTs may be useful for predicting tumor aggressiveness

Ampliação do Canal do Panamá

Após dez anos de jurisdição e administração panamenha no Canal do Panamá debate‐se hoje sobre sua ampliação. Palavras‐chave: Panamá; Canal do Panamá; Ampliação; Histórico

Mother and infant body mass index, breast milk leptin and their serum leptin values

Purpose: This study investigates correlations between mother and infant Body Mass Index (BMI), their serum leptin values and breast milk leptin concentration in early infancy. Subjects and Methods: We determined serum leptin values in 58 healthy infants and leptin values in their mothers’ breast milk, using radioimmunoassay (RIA). Infant and maternal anthropometrics were measured. Results: Median leptin concentration was 3.9 ng/mL (interquartile range (IQR): 2.75) in infant serum, 4.27 ng/mL (IQR: 5.62) in maternal serum and 0.89 ng/mL (IQR: 1.32) in breast milk. Median maternal BMI and weight were 24 kg/m2 (IQR: 4.41) and 64 kg (IQR: 15). Median infant BMI was 15.80 kg/cm2 (IQR: 4.02), while average weight was 5.130 kg (IQR: 1.627). Infants serum leptin values positively correlated with infants’ BMI (p = 0.001; r = 0.213) and breast milk leptin (p = 0.03; r = 0.285). Maternal serum leptin values positively correlated with maternal BMI (p = 0.000, r = 0.449) and breast milk leptin ones (p = 0.026; r = 0.322). Conclusion: Breast milk leptin and maternal BMI could influence infant serum leptin values. Further studies are needed to better elucidate the role of genetics and environment on infant leptin production and risk of obesity later in life

Signatures of an eruptive phase before the explosion of the peculiar core-collapse SN 2013gc

We present photometric and spectroscopic analysis of the peculiar core-collapse SN 2013gc, spanning seven years of observations. The light curve shows an early maximum followed by a fast decline and a phase of almost constant luminosity. At +200 days from maximum, a brightening of 1 mag is observed in all bands, followed by a steep linear luminosity decline after +300 d. In archival images taken between 1.5 and 2.5 years before the explosion, a weak source is visible at the supernova location, with mag$\approx$20. The early supernova spectra show Balmer lines, with a narrow ($\sim$560 km s$^{-1}$) P-Cygni absorption superimposed on a broad ($\sim$3400 km s$^{-1}$) component, typical of type IIn events. Through a comparison of colour curves, absolute light curves and spectra of SN 2013gc with a sample of supernovae IIn, we conclude that SN 2013gc is a member of the so-called type IId subgroup. The complex profile of the H$\alpha$ line suggests a composite circumstellar medium geometry, with a combination of lower velocity, spherically symmetric gas and a more rapidly expanding bilobed feature. This circumstellar medium distribution has been likely formed through major mass-loss events, that we directly observed from 3 years before the explosion. The modest luminosity ($M_I\sim-16.5$ near maximum) of SN 2013gc at all phases, the very small amount of ejected $^{56}$Ni (of the order of $10^{-3}$ M$_\odot$), the major pre-supernova stellar activity and the lack of prominent [O I] lines in late-time spectra support a fall-back core-collapse scenario for the massive progenitor of SN~2013gc.Comment: 20 pages, 11 figures, 8 tables, accepted by MNRA

The spectacular evolution of Supernova 1996al over 15 years: a low energy explosion of a stripped massive star in a highly structured environment

Spectrophotometry of SN 1996al carried out throughout 15 years is presented. The early photometry suggests that SN 1996al is a Linear type-II supernova, with an absolute peak of Mv ~ -18.2 mag. Early spectra present broad, asymmetric Balmer emissions, with super-imposed narrow lines with P-Cygni profile, and He I features with asymmetric, broad emission components. The analysis of the line profiles shows that the H and He broad components form in the same region of the ejecta. By day +142, the Halpha profile dramatically changes: the narrow P-Cygni profile disappears, and the Halpha is fitted by three emission components, that will be detected over the remaining 15 yrs of the SN monitoring campaign. Instead, the He I emissions become progressively narrower and symmetric. A sudden increase in flux of all He I lines is observed between 300 and 600 days. Models show that the supernova luminosity is sustained by the interaction of low mass (~1.15 Msun) ejecta, expelled in a low kinetic energy (~ 1.6 x 10^50 erg) explosion, with highly asymmetric circumstellar medium. The detection of Halpha emission in pre-explosion archive images suggests that the progenitor was most likely a massive star (~25 Msun ZAMS) that had lost a large fraction of its hydrogen envelope before explosion, and was hence embedded in a H-rich cocoon. The low-mass ejecta and modest kinetic energy of the explosion are explained with massive fallback of material into the compact remnant, a 7-8 Msun black hole.Comment: 27 pages, 23 figures, Accepted for publication in MNRA

Distributive/Integrative Negotiation Strategies in Cross-Cultural Contexts: A Comparative Study of the USA and Italy

Integrative and distributive negotiation strategies are a key paradigm of practice, teaching, and research. Are these US-formulated negotiation prototypes valid in the rest of the world? Adopting a cross-cultural view, we analyze a sample of 214 foreigners who detailed the negotiation behavior they faced in Italy (134) and in the United States (80). Implementing latent class analysis, we identify three clusters of negotiation prototypes. Our findings show how the Country is clearly a predictor for cluster membership, and peculiar cultural traits of the two groups contribute to explain the differences in negotiation strategies. Three prototypes emerged: a typically distributive, an emotional integrative (mostly Italian), and an impersonal integrative (mostly American). Results show how the handling of emotions is a crucial part of the interaction for Italian negotiators, regardless of their orientation towards negotiation strategies, implying a cultural influence toward emotions in negotiations