7,373 research outputs found
Probing strongly interacting atomic gases with energetic atoms
We investigate properties of an energetic atom propagating through strongly
interacting atomic gases. The operator product expansion is used to
systematically compute a quasiparticle energy and its scattering rate both in a
spin-1/2 Fermi gas and in a spinless Bose gas. Reasonable agreement with recent
quantum Monte Carlo simulations even at a relatively small momentum k/kF>1.5
indicates that our large-momentum expansions are valid in a wide range of
momentum. We also study a differential scattering rate when a probe atom is
shot into atomic gases. Because the number density and current density of the
target atomic gas contribute to the forward scattering only, its contact
density (measure of short-range pair correlation) gives the leading
contribution to the backward scattering. Therefore, such an experiment can be
used to measure the contact density and thus provides a new local probe of
strongly interacting atomic gases.Comment: 35 pages, 11 figures; (v4) published with the new titl
Verifying procedural programs via constrained rewriting induction
This paper aims to develop a verification method for procedural programs via a transformation into Logically Constrained Term Rewriting Systems (LCTRSs). To this end, we extend transformation methods based on integer TRSs to handle arbitrary data types, global variables, function calls and arrays, as well as encode safety checks. Then we adapt existing rewriting induction methods to LCTRSs and propose a simple yet effective method to generalize equations. We show that we can automatically verify memory safety and prove correctness of realistic functions. Our approach proves equivalence between two implementations, so in contrast to other works, we do not require an explicit specification in a separate specification language
Single crystal MgB2 with anisotropic superconducting properties
The discovery of superconductor in magnesium diboride MgB2 with high Tc (39
K) has raised some challenging issues; whether this new superconductor
resembles a high temperature cuprate superconductor(HTS) or a low temperature
metallic superconductor; which superconducting mechanism, a phonon- mediated
BCS or a hole superconducting mechanism or other new exotic mechanism may
account for this superconductivity; and how about its future for applications.
In order to clarify the above questions, experiments using the single crystal
sample are urgently required. Here we have first succeeded in obtaining the
single crystal of this new MgB2 superconductivity, and performed its electrical
resistance and magnetization measurements. Their experiments show that the
electronic and magnetic properties depend on the crystallographic direction.
Our results indicate that the single crystal MgB2 superconductor shows
anisotropic superconducting properties and thus can provide scientific basis
for the research of its superconducting mechanism and its applications.Comment: 7 pages pdf fil
On the experiments of Surfatron concept with use of capillary plasma.
In the middle of 1980th, the VpxB concept for accelerating electrons are found by Nishida et
al, with the use of plasma wave excited by high power microwave in the interaction with weakly
magnetized plasma. This acceleration concept was called “Surfatron effect” in the relativistic regime.
However, there is no experimental evidence so far in the relativistic regime, although the acceleration
efficiency is highest in all of the concepts based on the plasma wave acceleration scheme, and we are
now under experiments. In order to make longer the acceleration distances, there are several ideas
including 1)ducting of the electromagnetic waves (EM wave) in the preformed plasma, 2)selfchanneling
of the EM waves, and others. In this paper, the experimental results are shown on the
ducting phenomena by using strong microwave for simulating the laser ducting, and on the capillary
plasma scheme
Clinical impact of enhanced cytokine clearance with sustained high-efficiency daily diafiltration using a mediator-adsorbing membrane (SHEDD-fA) in patients with severe sepsis
Concept drift detection based on anomaly analysis
© Springer International Publishing Switzerland 2014. In online machine learning, the ability to adapt to new concept quickly is highly desired. In this paper, we propose a novel concept drift detection method, which is called Anomaly Analysis Drift Detection (AADD), to improve the performance of machine learning algorithms under non-stationary environment. The proposed AADD method is based on an anomaly analysis of learner’s accuracy associate with the similarity between learners’ training domain and test data. This method first identifies whether there are conflicts between current concept and new coming data. Then the learner will incrementally learn the non conflict data, which will not decrease the accuracy of the learner on previous trained data, for concept extension. Otherwise, a new learner will be created based on the new data. Experiments illustrate that this AADD method can detect new concept quickly and learn extensional drift incrementally
A case study for reversible computing: Reversible debugging of concurrent programs
Reversible computing allows one to run programs not only in the usual forward direction, but also backward. A main application area for reversible computing is debugging, where one can use reversibility to go backward from a visible misbehaviour towards the bug causing it. While reversible debugging of sequential systems is well understood, reversible debugging of concurrent and distributed systems is less settled. We present here two approaches for debugging concurrent programs, one based on backtracking, which undoes actions in reverse order of execution, and one based on causal consistency, which allows one to undo any action provided that its consequences, if any, are undone beforehand. The first approach tackles an imperative language with shared memory, while the second one considers a core of the functional message-passing language Erlang. Both the approaches are based on solid formal foundations
Electromechanical acoustic liner
A multi-resonator-based system responsive to acoustic waves includes at least two resonators, each including a bottom plate, side walls secured to the bottom plate, and a top plate disposed on top of the side walls. The top plate includes an orifice so that a portion of an incident acoustical wave compresses gas in the resonators. The bottom plate or the side walls include at least one compliant portion. A reciprocal electromechanical transducer coupled to the compliant portion of each of the resonators forms a first and second transducer/compliant composite. An electrical network is disposed between the reciprocal electromechanical transducer of the first and second resonator
Resummation of fermionic in-medium ladder diagrams to all orders
A system of fermions with a short-range interaction proportional to the
scattering length is studied at finite density. At any order , we
evaluate the complete contributions to the energy per particle
arising from combined (multiple) particle-particle and hole-hole rescatterings
in the medium. This novel result is achieved by simply decomposing the
particle-hole propagator into the vacuum propagator plus a medium-insertion and
correcting for certain symmetry factors in the -th power of the
in-medium loop. Known results for the low-density expansion up to and including
order are accurately reproduced. The emerging series in can be
summed to all orders in the form of a double-integral over an arctangent
function. In that representation the unitary limit can be taken
and one obtains the value for the universal Bertsch parameter. We
discuss also applications to the equation of state of neutron matter at low
densities and mention further extensions of the resummation method.Comment: 12 pages, 7 figures, submitted to Nuclear Physics
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