9,232 research outputs found
Pluri-Canonical Models of Supersymmetric Curves
This paper is about pluri-canonical models of supersymmetric (susy) curves.
Susy curves are generalisations of Riemann surfaces in the realm of super
geometry. Their moduli space is a key object in supersymmetric string theory.
We study the pluri-canonical models of a susy curve, and we make some
considerations about Hilbert schemes and moduli spaces of susy curves.Comment: To appear in the proceedings of the intensive period "Perspectives in
Lie Algebras", held at the CRM Ennio De Giorgi, Pisa, Italy, 201
Prognostic value of troponins in acute coronary syndrome depends upon patient age
Peer reviewedPostprin
The Submillimeter Array
The Submillimeter Array (SMA), a collaborative project of the Smithsonian
Astrophysical Observatory (SAO) and the Academia Sinica Institute of Astronomy
and Astrophysics (ASIAA), has begun operation on Mauna Kea in Hawaii. A total
of eight 6-m telescopes comprise the array, which will cover the frequency
range of 180-900 GHz. All eight telescopes have been deployed and are
operational. First scientific results utilizing the three receiver bands at
230, 345, and 690 GHz have been obtained and are presented in the accompanying
papers.Comment: 10 pages, 4 figure
From pre- to young Planetary Nebulae: radio continuum variability
Searching for variability, we have observed a sample of hot post-AGB stars
and young Planetary Nebulae candidates with the Very Large Array at 4.8, 8.4,
and 22.4 GHz. The sources had been previously detected in the radio continuum,
which is a proof that the central stars have started ionising their
circumstellar envelopes and an increase in radio flux with time can be expected
as a result of the progression of the ionisation front. Such a behaviour has
been found in IRAS 18062+2410, whose radio modelling has allowed us to
determine that its ionised mass has increased from 10^{-4} to 3.3 10^{-4} M_sun
in 8 years and its envelope has become optically thin at lower frequencies.
Different temporal behaviours have been found for three other sources. IRAS
17423-1755 has shown a possibly periodic pattern and an inversion of its radio
spectral index, as expected from a varying stellar wind. We estimate that the
radio flux arises from a very compact region around the central star (10^{15}
cm) with an electron density of 2 10^6 cm^{-3}. IRAS 22568+6141 and 17516-2525
have decreased their radio flux densities of about 10% per year over 4 years.
While a linear increase of the flux density with time points out to the
progression of the ionisation front in the envelope, decreases as well as
quasi-periodic patterns may indicate the presence of unstable stellar
winds/jets or thick dusty envelopes absorbing ionising photons.Comment: 9 pages, 5 figures, accepted for publication on MNRA
Observation of a HI leaving group following ultraviolet photolysis of CH 2I 2 in water and an ab initio investigation of the O-H insertion/HI elimination reactions of the CH 2I-I isopolyhalomethane species with H 2O and 2H 2O
Ultraviolet/visible absorption and pH measurements that indicate significant production of H + and I - product following ultraviolet photolysis of CH 2I 2 in liquid water are presented. As such, the chemical reactivity of isodiiodomethane (CH 2I-I) with H 2O and 2H 2O is explored using ab initio calculations and compared to previous results. The CH 2I-I isopolyhalomethane species is found to react with water by an O-H insertion/HI elimination reaction mechanism that forms a HI leaving group.published_or_final_versio
Fokker-Planck equation with variable diffusion coefficient in the Stratonovich approach
We consider the Langevin equation with multiplicative noise term which
depends on time and space. The corresponding Fokker-Planck equation in
Stratonovich approach is investigated. Its formal solution is obtained for an
arbitrary multiplicative noise term given by , and the
behaviors of probability distributions, for some specific functions of %
, are analyzed. In particular, for , the physical
solutions for the probability distribution in the Ito, Stratonovich and
postpoint discretization approaches can be obtained and analyzed.Comment: 6 pages in LATEX cod
Disorder raises the critical temperature of a cuprate superconductor
With the discovery of charge density waves (CDW) in most members of the
cuprate high temperature superconductors, the interplay between
superconductivity and CDW has become a key point in the debate on the origin of
high temperature superconductivity. Some experiments in cuprates point toward a
CDW state competing with superconductivity, but others raise the possibility of
a CDW-superconductivity intertwined order, or more elusive pair-density wave
(PDW). Here we have used proton irradiation to induce disorder in crystals of
LaBaCuO and observed a striking 50% increase of
accompanied by a suppression of the CDW. This is in clear
contradiction with the behaviour expected of a d-wave superconductor for which
both magnetic and non-magnetic defects should suppress . Our
results thus make an unambiguous case for the strong detrimental effect of the
CDW on bulk superconductivity in LaBaCuO. Using tunnel
diode oscillator (TDO) measurements, we find evidence for dynamic layer
decoupling in PDW phase. Our results establish irradiation-induced disorder as
a particularly relevant tuning parameter for the many families of
superconductors with coexisting density waves, which we demonstrate on
superconductors such as the dichalcogenides and LuIrSi.Comment: 10 pages, 7 figure
The EGRET high energy gamma ray telescope
The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (GRO) is sensitive in the energy range from about 20 MeV to about 30,000 MeV. Electron-positron pair production by incident gamma photons is utilized as the detection mechanism. The pair production occurs in tantalum foils interleaved with the layers of a digital spark chamber system; the spark chamber records the tracks of the electron and positron, allowing the reconstruction of the arrival direction of the gamma ray. If there is no signal from the charged particle anticoincidence detector which surrounds the upper part of the detector, the spark chamber array is triggered by two hodoscopes of plastic scintillators. A time of flight requirement is included to reject events moving backward through the telescope. The energy of the gamma ray is primarily determined by absorption of the energies of the electron and positron in a 20 cm deep NaI(Tl) scintillator
The EGRET data products
We describe the Energetic Gamma Ray Experiment Telescope (EGRET) data products which we anticipate will suffice for virtually all guest and archival investigations. The production process, content, availability, format, and the associated software of each product is described. Supplied here is sufficient detail for each researcher to do analysis which is not supported by extant software
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