Search results for "Active [Galaxies]"

Organocatalysts Fold to Generate an Active Site Pocket for the Mannich Reaction

2017

Catalysts containing urea, thiourea and tertiary amine groups fold into a three-dimensional organized structure in solution both in the absence as well as in the presence of substrates or substrate analogues, as indicated by solution NMR and computational studies. These foldamer catalysts promote Mannich reactions with both aliphatic and aromatic imines and malonate esters. Hammett plot and secondary kinetic isotope effects provide evidence for the C-C bond forming event as the turnoverlimiting step of the Mannich reaction. Computational studies suggest two viable pathways for the C-C bond formation step, differing in the activation modes of the malonate and imine substrates. The results sh…

Pratica didattica e caratteristiche dei docenti universitari che utilizzano Flipped Classroom

2020

La ricerca affronta il tema della pratica della Flipped Classroom (FC o classe capovolta) all’università, con un’attenzione particolare alla figura del docente e mira a definire le caratteristiche che accomunano i docenti che utilizzano questo metodo e come costoro percepiscono il loro ruolo. La metodologia di ricerca utilizzata è il metodo misto dello studio esploratorio sequenziale. Nella prima fase sono state condotte 20 interviste online in profondità con docenti italiani, spagnoli e britannici. Nella seconda fase è stato somministrato un questionario strutturato a 311 docenti dell’Università di Palermo, costruito partendo dai risultati ottenuti al termine della prima fase. I risultati …

Octave Spanning Supercontinuum in Titanium Dioxide Waveguides

2018

International audience; We report on the experimental generation of an octave-spanning supercontinuum in a 2.2 cm-long titanium dioxide optical waveguide with two zero dispersion wavelengths. The resulting on-chip supercontinuum reaches the visible wavelength range as well as the mid-infrared region by using a femtosecond fiber laser pump at 1.64 µm.

Hybrid evolutionary multi-objective optimization with enhanced convergence and diversity

2011

""Flora Italiana Digitale": an interactive identification tool for the Flora of Italy

2010

The digital facilities of the second edition of Pignatti's "Flora d'Italia" are presented. A software, called FID (i.e. "Flora Italiana Digitale") will link together a random-access interactive identification tool, a thesaurus, synoptic tables and one template for each single species, including a distribution map (referred to the Italian regions), "ecograms", a text-box and up to 24 high-resolution colour images. The FID follows a "shareware phylosophy". All contents and images can be integrated and/or replaced over time, in order to continuously improve the diagnostic and qualitative performance of the utilities provided. Ideally, the community of users should interact on the web, so that …

An ACT-R Based Humanoid Social Robot to Manage Storytelling Activities

2020

This paper describes an interactive storytelling system, accessible through the SoftBank robotic platforms NAO and Pepper. The main contribution consists of the interpretation of the story characters by humanoid robots, obtained through the definition of appropriate cognitive models, relying on the ACT-R cognitive architecture. The reasoning processes leading to the story evolution are based on the represented knowledge and the suggestions of the listener in critical points of the story. They are disclosed during the narration, to make clear the dynamics of the story and the feelings of the characters. We analyzed the impact of such externalization of the internal status of the characters t…

15GHz and jet properties of MOJAVE blazars

2013

We investigate the Fermi Large Area Telescope {gamma}-ray and 15GHz Very Long Baseline Array radio properties of a joint {gamma}-ray and radio-selected sample of active galactic nuclei (AGNs) obtained during the first 11 months of the Fermi mission (2008 August 4-2009 July 5). Our sample contains the brightest 173 AGNs in these bands above declination -30{deg} during this period, and thus probes the full range of {gamma}-ray loudness ({gamma}-ray to radio band luminosity ratio) in the bright blazar population. The latter quantity spans at least 4 orders of magnitude, reflecting a wide range of spectral energy distribution (SED) parameters in the bright blazar population. The BL Lac objects,…

1.5Jy MOJAVE AGN sample and 3FGL data

2016

We use the complete MOJAVE 1.5Jy sample of active galactic nuclei (AGNs) to examine the gamma-ray detection statistics of the brightest radio-loud blazars in the northern sky. We find that 23% of these AGNs were not detected above 0.1GeV by the Fermi-LAT during the four-year 3FGL catalog period partly because of an instrumental selection effect and partly due to their lower Doppler boosting factors. Blazars with synchrotron peaks in their spectral energy distributions located below 10^13.4^Hz also tend to have high-energy peaks that lie below the 0.1GeV threshold of the LAT, and are thus less likely to be detected by Fermi. The non-detected AGNs in the 1.5Jy sample also have significantly l…

MOJAVE VII. Blazar jet acceleration

2012

We discuss acceleration measurements for a large sample of extragalactic radio jets from the Monitoring Of Jets in Active Galactic Nuclei with VLBA Experiments (MOJAVE) program, which studies the parsec-scale jet structure and kinematics of a complete, flux-density-limited sample of active galactic nuclei (AGNs). Accelerations are measured from the apparent motion of individual jet features or "components" which may represent patterns in the jet flow. We find that significant accelerations are common both parallel and perpendicular to the observed component velocities. Cone search capability for table J/ApJ/706/1253/agn (Positions for AGN sources)

MOJAVE. XII. Acceleration of blazar jets

2015

We report on the acceleration properties of 329 features in 95 blazar jets from the MOJAVE Very Long Baseline Array program. Nearly half the features and three-quarters of the jets show significant changes in speed and/or direction. In general, apparent speed changes are distinctly larger than changes in direction, indicating that changes in the Lorentz factors of jet features dominate the observed speed changes rather than bends along the line of sight. Observed accelerations tend to increase the speed of features near the jet base, <~10-20pc projected, and decrease their speed at longer distances. The range of apparent speeds at a fixed distance in an individual jet can span a factor of a…