242 research outputs found
Multiple shells around G79.29+0.46 revealed from near-IR to millimeter data
Aiming to perform a study of the warm dust and gas in the luminous blue
variable star G79.29+0.46 and its associated nebula, we present infrared
Spitzer imaging and spectroscopy, and new CO J=2-->1 and 4-->3 maps obtained
with the IRAM 30m radio telescope and with the Submillimeter Telescope,
respectively. We have analyzed the nebula detecting multiple shells of dust and
gas connected to the star. Using Infrared Spectrograph-Spitzer spectra, we have
compared the properties of the central object, the nebula, and their
surroundings. These spectra show a rich variety of solid-state features
(amorphous silicates, polycyclic aromatic hydrocarbons, and CO2 ices) and
narrow emission lines, superimposed on a thermal continuum. We have also
analyzed the physical conditions of the nebula, which point to the existence of
a photo-dissociation region.Comment: Received by ApJ 2009 November 20, accepted for publication 2010
February 25, Published 2010 March 2
Pierre Mendès France et la recherche scientifique et technique
« La République a besoin de savants ; leurs découvertes, le rayonnement qui s'y attache et leurs applications contribuent à la grandeur d'un pays. Or, les crédits de la recherche sont dérisoires... », ainsi s'exprime Pierre Mendès France, député de l'Eure, le 3 juin 1953 devant l'Assemblée nationale en sollicitant l'investiture de président du Conseil. Ces quelques lignes, noyées dans un discours de plusieurs pages, ne sont pourtant pas passées inaperçues à l'époque car l'orateur apparaît com..
Useful Field of View Impairment in Partial Epilepsy
Patients with epilepsy are at elevated risk for automobile crashes.Most collisions in drivers with epilepsy are not seizure-related, but may insteadresult from cognitive effects of epilepsy and antiepileptic drugs (AEDs) upondriving performance. The Useful Field of View (UFOV) score has demonstratedgood sensitivity and specificity for predicting automobile crashes. The goal in thispilot study was to assess impairments in the UFOV in subjects with partialepilepsy. Participants included 20 subjects with partial epilepsy. Neurologicallynormal control subjects of comparable age also participated. UFOV was assessedin all participants using the Visual Attention Analyzer, Model 3000 (VisualResources, Inc.). UFOV Task scores were added to calculate a UFOV Total scorefor each subject. UFOV scores were higher on all UFOV tasks in subjects withpartial epilepsy compared to neurologically normal individuals of similar age (p\u3c0.05, Wilcoxon Rank Sum Test), suggesting a greater crash risk in individualswith partial epilepsy, even in the absence of an epileptic seizure. Causes ofimpaired UFOV scores include processing speed reduction, divided and selectiveattention impairments, and mild postoperative visual field deficits. Our ongoingstudies in drivers with epilepsy are aimed at further differentiating potentialeffects of seizures, antiepileptic drugs, and surgical lesions upon cognitiveabilities that are critical to safe automobile driving
Shocked gas layers surrounding the WR nebula NGC 2359
NGC 2359 is a Wolf-Rayet (W-R) nebula partially bound by a rather dense and
warm molecular cloud. We present the results derived from CO and CO
fully sampled maps of the molecular material with angular resolutions up to
12". We have detected three different velocity components, and determined their
spatial distribution and physical properties. The kinematics, morphology, mass
and density are clearly stratified with respect to the W-R star. These features
allow us to learn about the recent evolutionary history of HD 56925, because
the multiple layers could be associated to several energetic events which have
acted upon the surrounding circumstellar medium. Hence, a careful study of the
different shockfronts contain clues in determining the present and past
interaction of this evolved massive star with its surroundings. From the
analysis of the mass-loss history in massive stars like HD 56925, we suggest
that the multiple layers of shocked molecular gas are likely to be produced
during the earlier LBV phase and/or the actual W-R stage of HD 56925.Comment: Accepted by A&A. 12 pages, 7 figure
Neutrino Masses and Lepton Flavour Violation in Thick Brane Scenarios
We address the issue of lepton flavour violation and neutrino masses in the
``fat-brane'' paradigm, where flavour changing processes are suppressed by
localising different fermion field wave-functions at different positions (in
the extra dimensions) in a thick brane. We study the consequences of
suppressing lepton number violating charged lepton decays within this scenario
for lepton masses and mixing angles. In particular, we find that charged lepton
mass matrices are constrained to be quasi-diagonal. We further consider whether
the same paradigm can be used to naturally explain small Dirac neutrino masses
by considering the existence of three right-handed neutrinos in the brane, and
discuss the requirements to obtain phenomenologically viable neutrino masses
and mixing angles. Finally, we examine models where neutrinos obtain a small
Majorana mass by breaking lepton number in a far away brane and show that, if
the fat-brane paradigm is the solution to the absence of lepton number
violating charged lepton decays, such models predict, in the absence of flavour
symmetries, that charged lepton flavour violation will be observed in the next
round of rare muon/tau decay experiments.Comment: 33 pages, 9 eps figure
A Full Suite of Histone and Histone Modifying Genes Are Transcribed in the Dinoflagellate Lingulodinium
BACKGROUND: Dinoflagellates typically lack histones and nucleosomes are not observed in DNA spreads. However, recent studies have shown the presence of core histone mRNA sequences scattered among different dinoflagellate species. To date, the presence of all components required for manufacturing and modifying nucleosomes in a single dinoflagellate species has not been confirmed. METHODOLOGY AND RESULTS: Analysis of a Lingulodinium transcriptome obtained by Illumina sequencing of mRNA shows several different copies of each of the four core histones as well as a suite of histone modifying enzymes and histone chaperone proteins. Phylogenetic analysis shows one of each Lingulodinium histone copies belongs to the dinoflagellate clade while the second is more divergent and does not share a common ancestor. All histone mRNAs are in low abundance (roughly 25 times lower than higher plants) and transcript levels do not vary over the cell cycle. We also tested Lingulodinium extracts for histone proteins using immunoblotting and LC-MS/MS, but were unable to confirm histone expression at the protein level. CONCLUSION: We show that all core histone sequences are present in the Lingulodinium transcriptome. The conservation of these sequences, even though histone protein accumulation remains below currently detectable levels, strongly suggests dinoflagellates possess histones
The relationship between the perception of distributed leadership in secondary schools and teachers' and teacher leaders' job satisfaction and organizational commitment
This study investigates the relation between distributed leadership, the cohesion of the leadership team, participative decision-making, context variables, and the organizational commitment and job satisfaction of teachers and teacher leaders. A questionnaire was administered to teachers and teacher leaders (n=1770) from 46 large secondary schools. Multiple regression analyses and path analyses revealed that the study variables explained significant variance in organizational commitment. The degree of explained variance for job satisfaction was considerably lower compared to organizational commitment. Most striking was that the cohesion of the leadership team and the amount of leadership support was strongly related to organizational commitment, and indirectly to job satisfaction. Decentralization of leadership functions was weakly related to organizational commitment and job satisfaction
Transport Infrastructure Surveillance and Monitoring by Electromagnetic Sensing: The ISTIMES Project
The ISTIMES project, funded by the European Commission in the frame of a joint Call “ICT and Security” of the Seventh Framework Programme, is presented and preliminary research results are discussed. The main objective of the ISTIMES project is to design, assess and promote an Information and Communication Technologies (ICT)-based system, exploiting distributed and local sensors, for non-destructive electromagnetic monitoring of critical transport infrastructures. The integration of electromagnetic technologies with new ICT information and telecommunications systems enables remotely controlled monitoring and surveillance and real time data imaging of the critical transport infrastructures. The project exploits different non-invasive imaging technologies based on electromagnetic sensing (optic fiber sensors, Synthetic Aperture Radar satellite platform based, hyperspectral spectroscopy, Infrared thermography, Ground Penetrating Radar-, low-frequency geophysical techniques, Ground based systems for displacement monitoring). In this paper, we show the preliminary results arising from the GPR and infrared thermographic measurements carried out on the Musmeci bridge in Potenza, located in a highly seismic area of the Apennine chain (Southern Italy) and representing one of the test beds of the project
US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report
This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in
Dark Matter" held at University of Maryland on March 23-25, 2017.Comment: 102 pages + reference
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