7,132 research outputs found
A New Channel for the Detection of Planetary Systems Through Microlensing: II. Repeating Events
In the companion paper we began the task of systematically studying the
detection of planets in wide orbits () via microlensing surveys.
In this paper we continue, focusing on repeating events. We find that, if all
planetary systems are similar to our own Solar System, reasonable extensions of
the present observing strategies would allow us to detect 3-6 repeating events
per year along the direction to the Bulge. Indeed, if planetary systems with
multiple planets are common, then future monitoring programs which lead to the
discovery of thousands of stellar-lens events will likely discover events in
which several different planets within a single system serve as lenses, with
light curves exhibiting multiple repetitions. In this paper we discuss
observing strategies to maximize the discovery of all wide-orbit planet-lens
events. We also compare the likely detection rates of planets in wide orbits to
those of planets located in the zone for resonant lensing. We find that,
depending on the values of the planet masses and stellar radii of the lensed
sources (which determine whether or not finite source size is important), and
also on the sensitivity of the photometry used by observers, the detection of
planets in wide orbits may be the primary route to the discovery of planets via
microlensing. We also discuss how the combination of resonant and wide-orbit
events can help us to learn about the distribution of planetary system
properties (S 6.1). In addition, by determining the fraction of short-duration
events due to planets, we indirectly derive information about the fraction of
all short-duration events that may be due to low-mass MACHOs (S 6.2).Comment: 51 pages, 7 figures. To be published in the Astrophysical Journal, 20
February 1999. This completes the introduction to the discovery of planets in
wide orbits begun in astro-ph/9808075, also to appear in ApJ on 20 February
199
Evidence of positive tectonic inversion in the north-central sector of the Sicily Channel (Central Mediterranean)
In order to unravel the tectonic evolution of the north-central sector of the Sicily Channel (Central Mediterranean), a seismo-stratigraphic analysis of single- and multi-channel seismic reflection profiles has been carried out. This allowed to identify, between 20 and 50 km offshore the central-southern coast of Sicily, a ~80-km-long deformation belt, characterized by a set of WNW\u2013ESE to NW\u2013SE fault segments showing a poly-phasic activity. Within this belt, we observed: i) Miocene normal faults reactivated during Zanclean\u2013Piacenzian time by dextral strike-slip motion, as a consequence of the Africa\u2013Europe convergence; ii) releasing and restraining bend geometries forming well-developed pull-apart basins and compressive structures. In the central and western sectors of the belt, we identified local transpressional reactivations of Piacenzian time, attested by well-defined compressive features like push-up structures and fault-bend anticlines. The reconstruction of timing and style of tectonic deformation suggest a strike-slip reactivation of inherited normal faults and the local subsequent positive tectonic inversion, often documented along oblique thrust ramps. This pattern represents a key for an improved knowledge of the structural style of foreland fold-and-thrust belts propagating in a preexisting extensional domain. With regard to active tectonics and seismic hazards, recent GPS data and local seismicity events suggest that this deformation process could be still active and accomplished through deep-buried structures; moreover, several normal faults showing moderate displacements have been identified on top of the Madrepore Bank and Malta High, offsetting the Late Quaternary deposits. Finally, inside the northern part of the Gela Basin, multiple slope failures, originated during Pleistocene by the further advancing of the Gela Nappe, reveal tectonically induced potential instability processes
Dimensional Analysis and Stage-Discharge Relationships for Vegetated Weirs
The deduction of the weir flow stage-discharge relationship is a hydraulic problem generally solved by energy considerations and using the discharge coefficient to correct the gap between theoretical results and experimental measurements. In this context, the dimensional analysis represents an alternative to find simple and reliable equations to obtain the rating curve. In this study, the outflow process of vegetated weirs is investigated applying the pi-Theorem of dimensional analysis and the incomplete self-similarity theory. The aim of this paper is to propose a new theoretically-based stage-discharge relationship, and test its applicability by measurements recently published in the literature. The results showed that the errors in discharge estimate obtained by the proposed stage-discharge relationship are always less than or equal to +/- 10% and less than or equal to +/- 5% for 97-100% of cases. The main advantage of the proposed relationships is providing a single stage-discharge relationship, which has better performances than the equations reported in the literature and excludes the use of discharge coefficient
The Discovery of an X-ray/UV Stellar Flare from the Late-K/Early-M Dwarf LMC 335
We report the discovery of an X-ray/UV stellar flare from the source LMC 335,
captured by XMM-Newton in the field of the Large Magellanic Cloud. The flare
event was recorded continuously in X-ray for its first 10 hours from the
precursor to the late decay phases. The observed fluxes increased by more than
two orders of magnitude at its peak in X-ray and at least one in the UV as
compared to quiescence. The peak 0.1-7.0 keV X-ray flux is derived from the
two-temperature APEC model to be ~(8.4 +/- 0.6) x 10^-12 erg cm-2 s-1.
Combining astrometric information from multiple X-ray observations in the
quiescent and flare states, we identify the NIR counterpart of LMC 335 as the
2MASS source J05414534-6921512. The NIR color relations and spectroscopic
parallax characterize the source as a Galactic K7-M4 dwarf at a foreground
distance of (100 - 264) pc, implying a total energy output of the entire event
of ~(0.4 - 2.9) x 10^35 erg. This report comprises detailed analyses of this
late-K / early-M dwarf flare event that has the longest time coverage yet
reported in the literature. The flare decay can be modeled with two exponential
components with timescales of ~28 min and ~4 hours, with a single component
decay firmly ruled out. The X-ray spectra during flare can be described by two
components, a dominant high temperature component of ~40-60MK and a low
temperature component of ~10MK, with a flare loop length of about 1.1-1.3
stellar radius.Comment: 35 pages, 6 figures, 5 tables, accepted for publication in Ap
The IkB kinase inhibitor nuclear factor-kB essential modulator–binding domain peptide for inhibition of balloon injury-induced neointimal formation
Objective—The activation of nuclear factor-kB (NF-kB) is a crucial step in the arterial wall’s response to injury. The
identification and characterization of the NF-kB essential modulator– binding domain (NBD) peptide, which can block
the activation of the IkB kinase complex, have provided an opportunity to selectively abrogate the inflammation-induced
activation of NF-kB. The aim of the present study was to evaluate the effect of the NBD peptide on neointimal
formation.<br></br>
Methods and Results—In the rat carotid artery balloon angioplasty model, local treatment with the NBD peptide (300
microg/site) significantly reduced the number of proliferating cells at day 7 (by 40%; P<0.01) and reduced injury-induced neointimal formation (by 50%; P<0.001) at day 14. These effects were associated with a significant reduction of NF-kB activation and monocyte chemotactic protein-1 expression in the carotid arteries of rats treated with the peptide. In addition, the NBD peptide (0.01 to 1 micromol/L) reduced rat smooth muscle cell proliferation, migration, and invasion in
vitro. Similar results were observed in apolipoprotein E-/-, mice in which the NBD peptide (150 microg/site) reduced wire-induced neointimal formation at day 28 (by 47%; P<0.01).<br></br>
Conclusion—The NBD peptide reduces neointimal formation and smooth muscle cell proliferation/migration, both effects
associated with the inhibition of NF-kB activation
A New Channel for the Detection of Planetary Systems Through Microlensing: I. Isolated Events Due to Planet Lenses
We propose and evaluate the feasibility of a new strategy to search for
planets via microlensing. This new strategy is designed to detect planets in
"wide" orbits, i.e., with orbital separation, greater than .
Planets in wide orbits may provide the dominant channel for the microlensing
discovery of planets, particularly low-mass (e.g., Earth-mass) planets. This
paper concentrates on events in which a single planet serves as a lens, leading
to an isolated event of short duration. We point out that a distribution of
events due to lensing by stars with wide-orbit planets is necessarily
accompanied by a distribution of shorter- duration events. The fraction of
events in the latter distribution is proportional to the average value of
, where is the ratio between \pl and stellar masses. The position
of the peak or peaks also provides a measure of the mass ratios typical of
planetary systems. We study detection strategies that can optimize our ability
to discover isolated short-duration events due to lensing by planets, and find
that monitoring employing sensitive photometry is particularly useful. If
planetary systems similar to our own are common, even modest changes in
detection strategy should lead to the discovery of a few isolated events of
short duration every year. We therefore also address the issue of the
contamination due to stellar populations of any microlensing signal due to
low-mass MACHOs. We describe how, even for isolated events of short duration,
it will be possible to test the hypothesis that the lens was a planet instead
of a low-mass MACHO, if the central star of the planetary system contributes a
measurable fraction of the baseline flux.Comment: 37 pages, 6 figure. To be published in the Astrophysical Journal.
This is part one of a series of papers on microlensing by planetary systems
containing wide-orbit planets; the series represents a reorganization and
extension of astro-ph/971101
The diagnostic accuracy of the small fiber neuropathy symptoms inventory questionnaire (SFN-SIQ) for identifying pure small fiber neuropathy
A definite diagnosis of pure small fiber neuropathy (SFN) relies on specific diagnostic testing, such as skin biopsy, quantitative sensory testing (QST), and nociceptive evoked potentials, which require considerable resources that may not be widely available. Accordingly, diagnostic tools with easy implementation in non-specialist centers are warranted to identify patients who require second-level diagnostic tests. In this study, we aimed to test the accuracy of the Small Fiber Neuropathy Symptoms Inventory Questionnaire (SFN-SIQ) in diagnosing pure SFN. We enrolled 86 patients with suspected pure SFN. In these patients, we calculated the diagnostic accuracy of the SFN-SIQ using a combination of clinical examination, QST, and skin biopsy as a reference standard. We found that the SFN-SIQ showed an excellent ability to discriminate between patients with and without pure SFN, with 86% sensitivity and 70% specificity in the diagnosis of pure SFN. Our study providing the diagnostic yield of the SFN-SIQ for pure SFN diagnosis suggests that this questionnaire might be used to screen patients with suspected SFN and identify those requiring second-level diagnostic tests such as QST, skin biopsy, or nociceptive evoked potentials
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