1,251 research outputs found
Fractional smoothness and applications in finance
This overview article concerns the notion of fractional smoothness of random
variables of the form , where is a certain
diffusion process. We review the connection to the real interpolation theory,
give examples and applications of this concept. The applications in stochastic
finance mainly concern the analysis of discrete time hedging errors. We close
the review by indicating some further developments.Comment: Chapter of AMAMEF book. 20 pages
Charmonium Suppression with cc~ Dissociation by Strings
We study the production of cc~ pairs in nuclear reactions at SPS energies
within the covariant transport approach HSD. The production of cc~ is treated
perturbatively employing experimental cross sections while the interactions of
cc~ pairs with baryons are included by conventional cascade-type two-body
collisions. Adopting 6 mb for the cc~-baryon cross sections the data on J/\Psi
suppression in p+A reactions are reproduced in line with calculations based on
the Glauber model. Additionally the dissociation of the cc~ pairs by strings is
included in a purely geometrical way. We find good agreement with experimental
data from the NA38 and NA50 collaboration with an estimate for the string
radius of ~0.2-0.3 fm.Comment: 9 pages (LaTeX), 5 PS figure
Can Galactic Cosmic Rays Account for Solar 6Li Without Overproducing Gamma Rays?
Cosmic-ray interactions with interstellar gas produces both 6Li, which
accumulates in the interstellar medium (ISM), and mesons, which decay
to gamma-rays which propagate throughout the cosmos. Local 6Li abundances and
extragalactic gamma-rays thus have a common origin which tightly links them. We
exploit this connection to use gamma-ray observations to infer the contribution
to 6Li nucleosynthesis by standard Galactic cosmic-ray (GCR) interactions with
the ISM. Our calculation uses a carefully propagated cosmic-ray spectrum and
accounts for 6Li production from both fusion reactions () as well as from spallation channels ({p,\alpha+CNO \to ^6Li). We find
that although extreme assumptions yield a consistent picture, more realistic
ones indicate that solar 6Li cannot be produced by standard GCRs alone without
overproducing the hadronic gamma rays. Implications for the primordial 6Li
production by decaying dark matter and cosmic rays from cosmological structure
formation are discussed. Upcoming gamma-ray observations by GLAST will be
crucial for determining the resolution of this problem.Comment: 4 pages, 1 figure To be published in ApJ
Interpretation of the ion mass spectra in the mass range 25-35 obtained in the inner coma of Halley's comet by the HIS-sensor of the Giotto IMS Experiment
The IMS-HIS double-focussing mass spectrometer that flew on the Giotto spacecraft covered the mass per charge range from 12 to 56 (AMU/e). By comparing flight data, calibration data, and results of model calculations of the ion population in the inner coma, the absolute mass scale is established, and ions in the mass range 25 to 35 are identified. Ions resulting from protonation of molecules with high proton affinity are relatively abundant, enabling us to estimate relative source strengths for H2CO, CH3OH, HCN, and H2S, providing for the first time a positive in situ measurement of methanol. Also, upper limits for NO and some hydrocarbons are derived
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Spot Joining of Si3N4 and SIC Ceramics using Selective Area Laser Deposition (SALD) Technique
Mechanical Engineerin
Grasping the Links in the Chain: Understanding the Unintended Consequences of International Counter-Narcotics Measures for the EU
No abstract available
High Resolution Spectroscopy of the high galactic latitude RV Tauri star CE Virginis
Analysis of the surface composition of the suspected cool RV Tauri star CE
Vir shows no systematic trend in depletions of elements with respect to
condensation temperature. However, there is a significant depletion of the
elements with respect to the first ionization potential of the element. The
derived Li abundance of log (Li) = 1.50.2 indicates production
of Li in the star. Near infrared colours indicate sporadic dust formation close
to the photosphere.Comment: 12 pages, including 8 pages: Accepted for publication in MNRA
Recombination-ready Sindbis replicon expression vectors for transgene expression
<p>Abstract</p> <p>Background</p> <p>Sindbis viruses have been widely used as tools to study gene function in cells. Despite the utility of these systems, the construction and production of alphavirus replicons is time consuming and inefficient due to potential additional restriction sites within the insert region and lack of directionality for insert ligation. In this report, we present a system useful for producing recombinant Sindbis replicons that uses lambda phage recombination technology to rapidly and specifically construct replicon expression plasmids that contain insert regions in the desired orientation.</p> <p>Results</p> <p>Recombination of the gene of interest with the replicon plasmid resulted in nearly 100% recombinants, each of which contained a correctly orientated insert. Replicons were easily produced in cell culture and packaged into pseudo-infectious viral particles. Insect and mammalian cells infected with pseudo-infectious viral particles expressed various transgenes at high levels. Finally, inserts from persistently replicating replicon RNA were easily isolated and recombined back into entry plasmids for sequencing and subsequent analysis.</p> <p>Conclusion</p> <p>Replication-ready replicon expression plasmids make the use of alphavirus replicons fast and easy as compared to traditional replicon production methods. This system represents a significant step forward in the utility and ease of use of alphavirus replicons in the study of gene function.</p
Cluster structures on quantum coordinate rings
We show that the quantum coordinate ring of the unipotent subgroup N(w) of a
symmetric Kac-Moody group G associated with a Weyl group element w has the
structure of a quantum cluster algebra. This quantum cluster structure arises
naturally from a subcategory C_w of the module category of the corresponding
preprojective algebra. An important ingredient of the proof is a system of
quantum determinantal identities which can be viewed as a q-analogue of a
T-system. In case G is a simple algebraic group of type A, D, E, we deduce from
these results that the quantum coordinate ring of an open cell of a partial
flag variety attached to G also has a cluster structure.Comment: v2: minor corrections. v3: references updated, final version to
appear in Selecta Mathematic
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