3,938 research outputs found
Sub-computable Boundedness Randomness
This paper defines a new notion of bounded computable randomness for certain
classes of sub-computable functions which lack a universal machine. In
particular, we define such versions of randomness for primitive recursive
functions and for PSPACE functions. These new notions are robust in that there
are equivalent formulations in terms of (1) Martin-L\"of tests, (2) Kolmogorov
complexity, and (3) martingales. We show these notions can be equivalently
defined with prefix-free Kolmogorov complexity. We prove that one direction of
van Lambalgen's theorem holds for relative computability, but the other
direction fails. We discuss statistical properties of these notions of
randomness
Towards Verifying Nonlinear Integer Arithmetic
We eliminate a key roadblock to efficient verification of nonlinear integer
arithmetic using CDCL SAT solvers, by showing how to construct short resolution
proofs for many properties of the most widely used multiplier circuits. Such
short proofs were conjectured not to exist. More precisely, we give n^{O(1)}
size regular resolution proofs for arbitrary degree 2 identities on array,
diagonal, and Booth multipliers and quasipolynomial- n^{O(\log n)} size proofs
for these identities on Wallace tree multipliers.Comment: Expanded and simplified with improved result
Pion induced double charge exchange reactions in the Delta resonance region
We have applied the Giessen BUU (GiBUU) transport model to the description of
the double charge exchange (DCX) reaction of pions with different nuclear
targets at incident kinetic energies of 120-180 MeV . The DCX process is highly
sensitive to details of the interactions of pions with the nuclear medium and,
therefore, represents a major benchmark for any model of pion scattering off
nuclei at low and intermediate energies. The impact of surface effects, such as
the neutron skins of heavy nuclei, is investigated. The dependence of the total
cross section on the nuclear mass number is also discussed. We achieve a good
quantitative agreement with the extensive data set obtained at LAMPF.
Furthermore, we compare the solutions of the transport equations obtained in
the test-particle ansatz using two different schemes - the full and the
parallel ensemble method.Comment: 14 pages,9 figure
Non-Hausdorff Symmetries of C*-algebras
Symmetry groups or groupoids of C*-algebras associated to non-Hausdorff
spaces are often non-Hausdorff as well. We describe such symmetries using
crossed modules of groupoids. We define actions of crossed modules on
C*-algebras and crossed products for such actions, and justify these
definitions with some basic general results and examples.Comment: very minor changes. To appear in Math. An
Detection of Lyme disease and anaplasmosis pathogens via PCR in Pennsylvania deer ked
Borrelia burgdorferi and Anaplasma phagocytophilum are obligate intracellular parasites that maintain their life cycles in enzoonotic vector‐host cycles with Ixodes scapularis as a vector. In addition to ticks, the hosts are commonly infested with insects from the Hippoboscidae family. This study confirms the presence of B. burgdorferi and A. phagocytophilum in deer keds (Lipoptena cervi) removed from white‐tailed deer using PCR. Detection of these pathogens in deer ked represents a potential novel susceptibility of wildlife and also suggests the risk of transmission of these pathogens to humans and animals alike through the bite of an infected ectoparasite. This study represents the first instance in the U.S. of detection of tick‐borne pathogens in a member of the Hippoboscid family
Three-body collisions in Boltzmann-Uehling-Uhlenbeck theory
Aiming at a microscopic description of heavy ion collisions in the beam
energy region of about 10 A GeV, we extend the Giessen
Boltzmann-Uehling-Uhlenbeck (GiBUU) transport model by including a relativistic
mean field, in-medium baryon-baryon cross sections and three-body collisions.
The model is then compared with experimental data for central Au+Au collisions
at 2-10 A GeV and central Pb+Pb collisions at 30 and 40 A GeV on the proton
rapidity spectra, the midrapidity yields of , and
, and the transverse mass spectra of and .
The three-body collisions increase the inverse slope parameters of the hadron
-spectra to a good agreement with the data.Comment: 26 pages, 9 figures, figures added, discussion extended, results not
changed, version accepted in Phys. Rev.
Analysis of a jet stream induced gravity wave associated with an observed ice cloud over Greenland
International audienceA polar stratospheric ice cloud (PSC type II) was observed by airborne lidar above Greenland on 14 January 2000. It was the unique observation of an ice cloud over Greenland during the SOLVE/THESEO 2000 campaign. Mesoscale simulations with the hydrostatic HRM model are presented which, in contrast to global analyses, are capable to produce a vertically propagating gravity wave that induces the low temperatures at the level of the PSC afforded for the ice formation. The simulated minimum temperature is ~8 K below the driving analyses and ~4.5 K below the frost point, exactly coinciding with the location of the observed ice cloud. Despite the high elevations of the Greenland orography the simulated gravity wave is not a mountain wave. Analyses of the horizontal wind divergence, of the background wind profiles, of backward gravity wave ray-tracing trajectories, of HRM experiments with reduced Greenland topography and of several diagnostics near the tropopause level provide evidence that the wave is emitted from an intense, rapidly evolving, anticyclonically curved jet stream. The precise physical process responsible for the wave emission could not be identified definitely, but geostrophic adjustment and shear instability are likely candidates. In order to evaluate the potential frequency of such non-orographic polar stratospheric cloud events, the non-linear balance equation diagnostic is performed for the winter 1999/2000. It indicates that ice-PSCs are only occasionally generated by gravity waves emanating from spontaneous adjustment
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