753 research outputs found
Parallel Nonbinary LDPC Decoding on GPU
Nonbinary Low-Density Parity-Check (LDPC) codes
are a class of error-correcting codes constructed over the Galois
field GF(q) for q > 2. As extensions of binary LDPC codes,
nonbinary LDPC codes can provide better error-correcting
performance when the code length is short or moderate, but
at a cost of higher decoding complexity. This paper proposes a
massively parallel implementation of a nonbinary LDPC decoding
accelerator based on a graphics processing unit (GPU) to
achieve both great flexibility and scalability. The implementation
maps the Min-Max decoding algorithm to GPUâs massively
parallel architecture. We highlight the methodology to partition
the decoding task to a heterogeneous platform consisting of the
CPU and GPU. The experimental results show that our GPUbased
implementation can achieve high throughput while still
providing great flexibility and scalability.National Science Foundation (NSF
Live and Dead Nodes
In this paper, we explore the consequences of a distinction between `live'
and `dead' network nodes; `live' nodes are able to acquire new links whereas
`dead' nodes are static. We develop an analytically soluble growing network
model incorporating this distinction and show that it can provide a
quantitative description of the empirical network composed of citations and
references (in- and out-links) between papers (nodes) in the SPIRES database of
scientific papers in high energy physics. We also demonstrate that the death
mechanism alone can result in power law degree distributions for the resulting
network.Comment: 12 pages, 3 figures. To be published in Computational and
Mathematical Organization Theor
General Static Solutions of 2-dimensional Einstein-Dilaton-Maxwell-Scalar Theories
General static solutions of effectively 2-dimensional
Einstein-Dilaton-Maxwell-Scalar theories are obtained. Our model action
includes a class of 2-d dilaton gravity theories coupled with a gauge
field and a massless scalar field. Therefore it also describes the spherically
symmetric reduction of -dimensional Einstein-Scalar-Maxwell theories. The
properties of the analytic solutions are briefly discussed.Comment: 16 pages, Latex fil
Displaying the Heterogeneity of the SN 2002cx-like Subclass of Type Ia Supernovae with Observations of the Pan-STARRS-1 Discovered SN2009ku
SN2009ku, discovered by Pan-STARRS-1, is a Type Ia supernova (SNIa), and a
member of the distinct SN2002cx-like class of SNeIa. Its light curves are
similar to the prototypical SN2002cx, but are slightly broader and have a later
rise to maximum in g. SN2009ku is brighter (~0.6 mag) than other SN2002cx-like
objects, peaking at M_V = -18.4 mag - which is still significantly fainter than
typical SNeIa. SN2009ku, which had an ejecta velocity of ~2000 kms^-1 at 18
days after maximum brightness is spectroscopically most similar to SN2008ha,
which also had extremely low-velocity ejecta. However, SN2008ha had an
exceedingly low luminosity, peaking at M_V = -14.2 mag, ~4 mag fainter than
SN2009ku. The contrast of high luminosity and low ejecta velocity for SN2009ku
is contrary to an emerging trend seen for the SN2002cx class. SN2009ku is a
counter-example of a previously held belief that the class was more homogeneous
than typical SNeIa, indicating that the class has a diverse progenitor
population and/or complicated explosion physics. As the first example of a
member of this class of objects from the new generation of transient surveys,
SN2009ku is an indication of the potential for these surveys to find rare and
interesting objects.Comment: 7 pages, 3 figure
Finite-time fluctuations in the degree statistics of growing networks
This paper presents a comprehensive analysis of the degree statistics in
models for growing networks where new nodes enter one at a time and attach to
one earlier node according to a stochastic rule. The models with uniform
attachment, linear attachment (the Barab\'asi-Albert model), and generalized
preferential attachment with initial attractiveness are successively
considered. The main emphasis is on finite-size (i.e., finite-time) effects,
which are shown to exhibit different behaviors in three regimes of the
size-degree plane: stationary, finite-size scaling, large deviations.Comment: 33 pages, 7 figures, 1 tabl
Spin-parity dependent tunneling of magnetization in single-molecule magnets
Single-molecule magnets facilitate the study of quantum tunneling of
magnetization at the mesoscopic level. The spin-parity effect is among the
fundamental predictions that have yet to be clearly observed. It is predicted
that quantum tunneling is suppressed at zero transverse field if the total spin
of the magnetic system is half-integer (Kramers degeneracy) but is allowed in
integer spin systems. The Landau-Zener method is used to measure the tunnel
splitting as a function of transverse field. Spin-parity dependent tunneling is
established by comparing the transverse field dependence of the tunnel
splitting of integer and half-integer spin systems.Comment: 4 pages, 6 figure
Portfolio Vol. II N 3
Jeffers, Robinson. From \u27The Beaks of Eagles\u27 . Poem. 6.
Clement, Harry. Mr. Bigger Tries Faith . Prose. 7.
Shaw, A.A. Students of Denison . Prose. 9
Deweerd, H.A. New German War Prophets . Prose. 11.
West, Bill C. Reproach . Poem. 14.
West, Bill C. Dilemma . Poem. 14.
Manship, Paul. Dancer and Gazelles . Picture. 14.
Saunders, Paul. Review of New Books . Prose. 15.
Smith, Bob. Review of New Records . Prose. 15.
Picasso, Pablo. Nude (Pink) . Picture. 16.
Korbel, Mario. The Andante . Picture. 16.
Bethune, Don. Review of \u27Susan and God\u27 . Prose. 17.
Baily, Bernard. Thornton Wilder\u27s \u27Out Town Reviewed . 17.
Maxwell, Robert. Reflections . Poem. 18.
Carter, Clarence Holbrook. July . Picture. 18.
Browne, Phil. The Drag . Picture. 2.
Browne, Phil. A Faithful Servant . Prose. 19.
Hanna, Stanley. Jazz . Poem. 20.
Hanna, Stanley. M.A. . Poem. 20.
Whistler, James McNeill. Rotherhithe .
Wager, Dick. Black . Poem. 22.
Wager, Dick. Ruthless . Poem. 22.
Wager, Dick. Train . Poem. 22.
Martindale, Virginia. Song of a Cynic . Poem. 22.
Blazys, Alexander. Russian Dancers . Picture. 22.
Price II, Ira. The Rains Fell . Prose. 5
Pan-STARRS Pixel Analysis: Source Detection and Characterization
Over 3 billion astronomical sources have been detected in the more than 22 million orthogonal transfer CCD images obtained as part of the Pan-STARRS1 3Ď survey. Over 85 billion instances of those sources have been automatically detected and characterized by the Pan-STARRS Image Processing Pipeline photometry software, psphot. This fast, automatic, and reliable software was developed for the Pan-STARRS project but is easily adaptable to images from other telescopes. We describe the analysis of the astronomical sources by psphot in general as well as for the specific case of the third processing version used for the first two public releases of the Pan-STARRS 3Ď Survey data
Stratification of COPD patients by previous admission for targeting of preventative care
SummaryBackgroundHospital admissions for exacerbations of chronic obstructive pulmonary disease (COPD) impact considerably on disease evolution and healthcare provision. Building on previous studies, this study postulated that COPD patients could be stratified by risk of admission to determine which groups provide the greatest burden on resources, and how interventions should be targeted to prevent admissions.MethodsCOPD admissions during 1997â2003 in three Strategic Health Authorities in England were analysed (n=80,291). Patients admitted during winter (1 Novemberâ31 March) were stratified into three groups according to the number of admissions during the previous year: 0 (NIL), 1â2 (MOD) or âĽ3 (FRQ). Winter weeks were classified as âaverageâ, âabove averageâ, âhighâ, or âvery highâ risk, compared with the long-term mean.ResultsThe risk of admission during winter for FRQ and MOD patients was 40% and 12% respectively. NIL patients contributed to 70% of winter admissions, and 90% of the variation between âaverageâ and âvery highâ weeks, versus 9% and 1% for MOD and FRQ.ConclusionsPatients with no previous admissions have lower individual risk, but contribute to a high overall utilisation of health care resources and should be targeted to prevent admissions. Focusing upon high-risk patients (frequent attenders or more severe) may only reduce a small proportion of admissions, and therefore clinicians should ensure that all COPD patients receive appropriate therapy to reduce risk of exacerbations
Hamiltonian Description of Composite Fermions: Magnetoexciton Dispersions
A microscopic Hamiltonian theory of the FQHE, developed by Shankar and myself
based on the fermionic Chern-Simons approach, has recently been quite
successful in calculating gaps in Fractional Quantum Hall states, and in
predicting approximate scaling relations between the gaps of different
fractions. I now apply this formalism towards computing magnetoexciton
dispersions (including spin-flip dispersions) in the , 2/5, and 3/7
gapped fractions, and find approximate agreement with numerical results. I also
analyse the evolution of these dispersions with increasing sample thickness,
modelled by a potential soft at high momenta. New results are obtained for
instabilities as a function of thickness for 2/5 and 3/7, and it is shown that
the spin-polarized 2/5 state, in contrast to the spin-polarized 1/3 state,
cannot be described as a simple quantum ferromagnet.Comment: 18 pages, 18 encapsulated ps figure
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