Search results for "Rome"

First M87 Event Horizon Telescope Results. VI. The Shadow and Mass of the Central Black Hole

2019

We present measurements of the properties of the central radio source in M87 using Event Horizon Telescope data obtained during the 2017 campaign. We develop and fit geometric crescent models (asymmetric rings with interior brightness depressions) using two independent sampling algorithms that consider distinct representations of the visibility data. We show that the crescent family of models is statistically preferred over other comparably complex geometric models that we explore. We calibrate the geometric model parameters using general relativistic magnetohydrodynamic (GRMHD) models of the emission region and estimate physical properties of the source. We further fit images generated fro…

Characterization of a Newly Developed Aircraft-Based Laser Ablation Aerosol Mass Spectrometer (ALABAMA) and First Field Deployment in Urban Pollution…

2011

We present here the development and first field deployment of a novel Aircraft-based Laser ABlation Aerosol MAss spectrometer (ALABAMA), which is capable of measuring the chemical composition and size of individual ambient aerosol particles in the size range between 150 and 900 nm. The instrument uses a continuous wave 532 nm laser to size and detect the particles, a pulsed 266 nm laser to ablate and ionize the particles, and a bipolar, Z-shaped time-of-flight mass spectrometer to detect positive and negative ions. The ALABAMA fits into a 19"-aircraft rack of 150 cm height and has a total weight of 140 kg, thus currently being one of the smallest and lightest-weight instruments of its type.…

Time domain astronomy with the THESEUS satellite

2021

THESEUS is a medium size space mission of the European Space Agency, currently under evaluation for a possible launch in 2032. Its main objectives are to investigate the early Universe through the observation of gamma-ray bursts and to study the gravitational waves electromagnetic counterparts and neutrino events. On the other hand, its instruments, which include a wide field of view X-ray (0.3-5 keV) telescope based on lobster-eye focussing optics and a gamma-ray spectrometer with imaging capabilities in the 2-150 keV range, are also ideal for carrying out unprecedented studies in time domain astrophysics. In addition, the presence onboard of a 70 cm near infrared telescope will allow simu…

Evidence for marine biogenic influence on summertime Arctic aerosol

2017

International audience; We present vertically-resolved observations of aerosol composition during pristine summertime Arctic background conditions. The methansulfonic acid (MSA)-to-sulfate ratio peaked near the surface (mean 0.10), indicating a contribution from ocean-derived biogenic sulfur. Similarly, the organic aerosol (OA)-to-sulfate ratio increased towards the surface (mean 2.0). Both MSA-to-sulfate and OA-to-sulfate ratios were significantly correlated with FLEXPART-WRF-predicted airmass residence time over open water, indicating marine influenced OA. External mixing of sea salt aerosol from a larger number fraction of organic, sulfate and amine-containing particles, together with lo…

Modelling soil moisture at SMOS scale by use of a SVAT model over the Valencia Anchor Station

2010

16 páginas, 9 figuras, 5 tablas.

Chemical and mineralogical analyses on stones from Sagunto Castle (Spain)

2019

Abstract For the first time, an archaeometric study was carried out on the carbonate rock ashlars of the Sagunto Castle. The studied site is one of the most important and best preserved Spanish archaeological and architectural monuments, characterized by different construction phases from the Roman period to Modern Ages. Forty samples collected from thirteen different structures of Sagunto Castle and two quarries, located in the Sagunto's hill were used for comparative purposes. The samples were analyzed by X-ray diffraction, X-ray fluorescence and inductively coupled plasma mass spectrometry to determine their mineralogical and elemental composition. The obtained data show similar chemical…

A new method for the identification of archaeological soils by their spectral signatures in the vis-NIR region

2020

Abstract This paper introduces a statistical method to identify spectral signatures of buried archaeological remains and distinguish them from spectra of the background soil in the visible to near infrared region. The proposed method is based on the Principal Component Analysis (PCA). The difference between an archaeological spectrum and non-archaeological soil spectra is quantified by a so-called R value. R values larger than 1 indicate that the spectrum represents an archaeological material. The method is successfully applied to samples from five study sites in Italy and Hungary with special conditions. The reflection spectra are taken in a time-efficient way with a field spectrometer. Th…

2017

We present a new multi-analytical approach to the characterization of black pigments in Spanish Levantine rock art. This new protocol seeks to identify the raw materials that were used, as well as reconstruct the different technical gestures and decision-making processes involved in the obtaining of these black pigments. For the first of these goals, the pictorial matter of the black figurative motifs documented at the Les Dogues rock art shelter (Ares del Maestre, Castellon, Spain) was characterized through the combination of physicochemical and archeobotanical analyses. During the first stage of our research protocol, in situ and non-destructive analyses were carried out by means of porta…

Pace-of-life in a social insect: behavioral syndromes in ants shift along a climatic gradient

2017

Lay SummaryLinks between behavioral traits can shift with the local climate. We show that behavioral associations with temperature not only occur across, but also within populations. At warmer sites ant colonies increased their exploration and foraging activity, but were less aggressive. Moreover, at these warmer sites, more positive links were found between behaviors within populations compared to colder sites, where more negative links prevailed. Our study suggests that associations between behaviors shift along climatic gradients.

Floral scent in a sexually deceptive Ophrys orchid: from headspace collections to solvent extractions

2018

Sexually deceptive orchid flowers use visual, tactile and olfactory cues of female insects in order to attract males of one or a few closely related species as pollinators. Ophrys L. is the most species-rich genus of sexually deceptive orchids in the Mediterranean Basin. Despite Ophrys pollinated by Andrena male bees use alkanes and mainly alkenes with specific double-bond positions as key signals that trigger pseudocopulatory behavior, some volatile organic compounds (VOCs) with low molecular weight were found as long-range attractants non-eliciting copulatory behavior. Since floral scents in Ophrys have been extensively studied by solvent extractions here we aimed to understand which flor…