1,310 research outputs found
The spectroscopic evolution of the -ray emitting classical nova Nova Mon 2012. I. Implications for the ONe subclass of classical novae
Nova Mon 2012 was the first classical nova to be detected as a high energy
-ray transient, by Fermi-LAT, before its optical discovery. We study a
time sequence of high resolution optical echelle spectra (Nordic Optical
Telescope) and contemporaneous NOT, STIS UV, and CHIRON echelle spectra (Nov
20/21/22). We use [O III] and H line fluxs to constrain the properties
of the ejecta. We derive the structure from the optical and UV line profiles
and compare our measured line fluxes for with predictions using Cloudy with
abundances from other ONe novae. Mon 2012 is confirmed as an ONe nova. We find
E(B-V)=0.850.05 and hydrogen column density
cm. The corrected continuum luminosity is nearly the same in the entire
observed energy range as V1974 Cyg, V382 Mon, and Nova LMC 2000 at the same
epoch after outburst. The distance, about 3.6 kpc, is quite similar to V1974
Cyg. The line profiles can be modeled using an axisymmetric bipolar geometry
for the ejecta with various inclinations of the axis to the line of sight, 60
\le i \le 80 degrees, an opening angle of \approx\Delta
R/R(t)\approx 0.4f\approx 0.1-0.3\leq 6\times
10^{-5}_\odot\gamma$-ray emission may be a generic phenomenon, common to all ONe novae,
possibly to all classical novae, and connected with acceleration and emission
processes within the ejecta (abstract severely truncated).Comment: Submitted to A&A 9/1/2013; Accepted 27/2/2013 (in press
The spectroscopic evolution of the recurrent nova T Pyxidis during its 2011 outburst. II.The optically thin phase and the structure of the ejecta in recurrent novae
We continue our study of the physical properties of the recurrent nova T Pyx,
focussing on the structure of the ejecta in the nebular stage of expansion
during the 2011 outburst. The nova was observed contemporaneously with the
Nordic Optical Telescope (NOT), at high resolution spectroscopic resolution (R
~ 65000) on 2011 Oct. 11 and 2012 Apr. 8 (without absolute flux calibration),
and with the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble
Space Telescope, at high resolution (R ~ 30000) on 2011 Oct. 10 and 2012 Mar.
28 (absolute fluxes). We use standard plasma diagnostics (e.g. [O III] and [N
II] line ratios and the H line fluxes) to constrain electron densities
and temperatures. Using Monte Carlo modeling of the ejecta, we derive the
structure and filling factor from comparisons to the optical and ultraviolet
line profiles. The ejecta can be modeled using an axisymmetric conical --
bipolar -- geometry with a low inclination of the axis to the line of sight,
i=15+/-5 degrees, compatible with published results from high angular
resolution optical spectro-interferometry. The structure is similar to that
observed in the other short orbital period recurrent novae during their nebular
stages. We show that the electron density scales as as expected from a
ballistically ejected constant mass shell; there is no need to invoke a
continuing mass outflow following the eruption. The derived mass for the ejecta
with filling factor f ~ 3%, M_ej ~ 2E-6$M_sun is similar to that obtained for
other recurrent nova ejecta but inconsistent with the previously reported
extended optically thick epoch of the explosion. We suggest that the system
underwent a common envelope phase following the explosion that produced the
recombination event. Implications for the dynamics of the recurrent novae are
discussed. (truncated)Comment: accepted for publication in A&A (10 Nov. 2012), 10 pgs, 16 fig
Light gravitino production in association with gluinos at the LHC
We study the jets plus missing energy signature at the LHC in a scenario
where the gravitino is very light and the gluino is the next-to-lightest
supersymmetric particle and promptly decays into a gluon and a gravitino. We
consider both associated gravitino production with a gluino and gluino pair
production. By merging matrix elements with parton showers, we generate
inclusive signal and background samples and show how information on the gluino
and gravitino masses can be obtained by simple final state observables.Comment: 18 pages, 8 figures, 1 table; v2: typos corrected, version to appear
in JHE
TRANSMIT: Training Research and Applications Network to Support the Mitigation of Ionospheric Threats
TRANSMIT is an initiative funded by the European Commission through a Marie Curie Initial Training Network (ITN). Main aim of such networks is to improve the career perspectives of researchers who are in the first five years of their research career in both public and private sectors. In particular TRANSMIT will provide a coordinated program of academic and industrial training, focused on atmospheric phenomena that can significantly impair a wide range of systems and applications that are at the core of several activities embedded in our daily life. TRANSMIT deals with the harmful effects of the ionosphere on these systems, which will become increasingly significant as we approach the next solar maximum, predicted for 2013. Main aim of the project is to develop real time integrated state of the art tools to mitigate ionospheric threats to Global Navigation Satellite Systems (GNSS) and several related applications, such as civil aviation, marine navigation and land transportation. The project will provide Europe with the next generation of researchers in this field, equipping them with skills developed through a comprehensive and coordinated training program. Theirs research projects will develop real time integrated state of the art tools to mitigate these ionospheric threats to GNSS and several applications that rely on these systems. The main threat to the reliable and safe operation of GNSS is the variable propagation conditions encountered by GNSS signals as they pass through the ionosphere. At a COST 296 MIERS (Mitigation of Ionospheric Effects on Radio Systems) workshop held at the University of Nottingham in 2008, the establishment of a sophisticated Ionospheric Perturbation Detection and Monitoring (IPDM) network (http://ipdm.nottingham.ac.uk/) was proposed by European experts and supported by the European Space Agency (ESA) as the way forward to deliver the state of the art to protect the range of essential systems vulnerable to these ionospheric threats. Through a set of carefully designed research work packages TRANSMIT will be the enabler of the IPDM network. The goal of TRANSMIT is therefore to provide a concerted training programme including taught courses, research training projects, secondments at the leading European institutions, and a set of network wide events, with summer schools, workshops and a conference, which will arm the researchers of tomorrow with the necessary skills and knowledge to set up and run the proposed service. TRANSMIT will count on an exceptional set of partners, encompassing both academia and end users, including the aerospace and satellite communications sectors, as well as GNSS system designers and service providers, major user operators and receiver manufacturers. TRANSMIT's objectives are: A. Develop new techniques to detect and monitor ionospheric threats, with the introduction of new prediction and forecasting models, mitigation tools and improved system design; B. Advance the physical modeling of the underlying processes associated with the ionospheric plasma environment and the knowledge of its influences on human activity; C. Establish a prototype of a real time system to monitor the ionosphere, capable of providing useful assistance to users, which exploits all available resources and adds value for European services and products; D. Incorporate solutions to this system that respond to all end user needs and that are applicable in all geographical regions of European interest (polar, high and mid-latitudes, equatorial region). TRANSMIT will pave the way to establish in Europe a system capable of mitigating ionospheric threats on GNSS signals in real tim
Exploring the adoption of precision agriculture for irrigation in the context of agriculture 4.0: The key role of internet of things
In recent years, the concept of Agriculture 4.0 has emerged as an evolution of precision agriculture (PA) through the diffusion of the Internet of things (IoT). There is a perception that the PA adoption is occurring at a slower pace than expected. Little research has been carried out about Agriculture 4.0, as well as to farmer behavior and operations management. This work explores what drives the adoption of PA in the Agriculture 4.0 context, focusing on farmer behavior and operations management. As a result of a multimethod approach, the factors explaining the PA adoption in the Agriculture 4.0 context and a model of irrigation operations management are proposed. Six simulation scenarios are performed to study the relationships among the factors involved in irrigation planning. Empirical findings contribute to a better understanding of what Agriculture 4.0 is and to expand the possibilities of IoT in the PA domain. This work also contributes to the discussion on Agriculture 4.0, thanks to multidisciplinary research bringing together the different perspectives of PA, IoT and operations management. Moreover, this research highlights the key role of IoT, considering the farmer’s possible choice to adopt several IoT sensing technologies for data collection
Levantamento de plantas daninhas na cultura do cajueiro nos baixoes agricolas piauienses.
Levantamento de plantas daninhas na cultura do cajueiro nos baixoes agricolas piauienses.bitstream/CNPAT/7855/1/ct_89.pd
Eficácia de endectocidas em infestações naturais por Cochliomyia hominivorax (Mosca-varejeira) em bezerros no Pantanal
Todos os endectocidas injetáveis testados reduzem significativamente a ocorrência de miÃases umbilicais. Entretanto, por sua maior eficácia, o uso de produtos à base de doramectina é recomendável no manejo extensivo de bezerros recém-nascidos no Pantanal.bitstream/item/37464/1/CT90.pd
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