47 research outputs found
Physical Conditions in the Foreground Gas of Reflection Nebulae: NGC 2023, vdB 102, and NGC 7023
High resolution optical spectra of HD 37903 and HD 147009, which illuminate
the reflection nebulae, NGC 2023 and vdB 102, were obtained for comparison with
our results for HD 200775 and NGC 7023. Ground-based measurements of the
molecules, CH, C, and CN, and the atoms, Na I and K I, were analyzed to
extract physical conditions in the foreground cloud. Estimates of the gas
density, gas temperature and flux of ultraviolet radiation were derived and
were compared with the results from infrared and radio studies of the main
molecular cloud. The conditions are similar to those found in studies of
diffuse clouds. The foreground material is less dense than the gas in the
molecular cloud behind the star(s). The gas temperature was set at 40 K, the
temperature determined for the foreground gas in NGC 7023. The flux of
ultraviolet radiation was found to be less intense than in the molecular
material behind the star(s). The column densities of Na I and K I were
reproduced reasonably well when the extinction curve for the specific line of
sight was adopted. We obtained NEWSIPS data from the IUE archive for HD 37903
and HD 200775. The ultraviolet data on C I and CO allow extraction of the
physical conditions by alternate methods. General agreement among the various
diagnostics was found, leading to self-consistent pictures of the foreground
photodissociation regions. An Appendix describes checks on the usefulness of
IUE NEWSIPS data for interstellar studies. (Abridged)Comment: 65 pages, 18 tables, 14 figures, Accepted for publication in ApJ
Overview of recent TJ-II stellarator results
The main results obtained in the TJ-II stellarator in the last two years are reported. The most important topics investigated have been modelling and validation of impurity transport, validation of gyrokinetic simulations, turbulence characterisation, effect of magnetic configuration on transport, fuelling with pellet injection, fast particles and liquid metal plasma facing components. As regards impurity transport research, a number of working lines exploring several recently discovered effects have been developed: the effect of tangential drifts on stellarator neoclassical transport, the impurity flux driven by electric fields tangent to magnetic surfaces and attempts of experimental validation with Doppler reflectometry of the variation of the radial electric field on the flux surface. Concerning gyrokinetic simulations, two validation activities have been performed, the comparison with measurements of zonal flow relaxation in pellet-induced fast transients and the comparison with experimental poloidal variation of fluctuations amplitude. The impact of radial electric fields on turbulence spreading in the edge and scrape-off layer has been also experimentally characterized using a 2D Langmuir probe array. Another remarkable piece of work has been the investigation of the radial propagation of small temperature perturbations using transfer entropy. Research on the physics and modelling of plasma core fuelling with pellet and tracer-encapsulated solid-pellet injection has produced also relevant results. Neutral beam injection driven Alfvénic activity and its possible control by electron cyclotron current drive has been examined as well in TJ-II. Finally, recent results on alternative plasma facing components based on liquid metals are also presentedThis work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 under Grant Agreement No. 633053. It has been partially funded by the Ministerio de Ciencia, Inovación y Universidades of Spain under projects ENE2013-48109-P, ENE2015-70142-P and FIS2017-88892-P. It has also received funds from the Spanish Government via mobility grant PRX17/00425. The authors thankfully acknowledge the computer resources at MareNostrum and the technical support provided by the Barcelona S.C. It has been supported as well by The Science and Technology Center in Ukraine (STCU), Project P-507F
Diversity of Trypanosoma cruzi stocks and clones derived from Chagas disease patients: I-Behavioral characterization in vitro
ARGO-YBJ constraints on very high energy emission from GRBs
The ARGO-YBJ (Astrophysical Radiation Ground-based Observatory at YangBaJing)
experiment is designed for very high energy -astronomy and cosmic ray
researches. Due to the full coverage of a large area () with
resistive plate chambers at a very high altitude (4300 m a.s.l.), the ARGO-YBJ
detector is used to search for transient phenomena, such as Gamma-ray bursts
(GRBs). Because the ARGO-YBJ detector has a large field of view (2 sr)
and is operated with a high duty cycle (90%), it is well suited for GRB
surveying and can be operated in searches for high energy GRBs following alarms
set by satellite-borne observations at lower energies. In this paper, the
sensitivity of the ARGO-YBJ detector for GRB detection is estimated. Upper
limits to fluence with 99% confidence level for 26 GRBs inside the field of
view from June 2006 to January 2009 are set in the two energy ranges 10100
GeV and 10 GeV1 TeV.Comment: accepted for publication in Astroparticle Physic
Cognitive Neuropsychology of HIV-Associated Neurocognitive Disorders
Advances in the treatment of the human immunodeficiency virus (HIV) have dramatically improved survival rates over the past 10 years, but HIV-associated neurocognitive disorders (HAND) remain highly prevalent and continue to represent a significant public health problem. This review provides an update on the nature, extent, and diagnosis of HAND. Particular emphasis is placed on critically evaluating research within the realm of cognitive neuropsychology that aims to elucidate the component processes of HAND across the domains of executive functions, motor skills, speeded information processing, episodic memory, attention/working memory, language, and visuoperception. In addition to clarifying the cognitive mechanisms of HAND (e.g., impaired cognitive control), the cognitive neuropsychology approach may enhance the ecological validity of neuroAIDS research and inform the development of much needed novel, targeted cognitive and behavioral therapies