4,604 research outputs found
Nonomuraea monospora sp. nov., an actinomycete isolated from cave soil in Thailand, and emended description of the genus Nonomuraea
A novel actinomycete, designated strain PT708T, was isolated from cave soil collected in Pha Tup Cave Forest Park, Nan province, Thailand. It produced compounds with antimicrobial and anticancer activities. Its chemotaxonomic properties were consistent with those of members of the genus Nonomuraea . The major menaquinone was MK-9(H4), with minor amounts of MK-9(H6), MK-9(H2), MK-10(H2) and MK-8(H4). The polar lipid profile contained phosphatidylmonomethylethanolamine, diphosphatidylglycerol, hydroxy-phosphatidylmonomethylethanolamine, hydroxy-phosphatidylethanolamine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol mannoside and phosphatidylinositol. The major fatty acids were iso-C16 : 0, 10-methyl C17 : 0, C16 : 0 and C17 : 1ω6c. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain PT708T belonged to the genus Nonomuraea and was most closely related to Nonomuraea rhizophila YIM 67092T (98.50 % sequence similarity) and Nonomuraea rosea GW 12687T (98.30 %). The genomic DNA G+C content of strain PT708T was 73.3 mol%. Unlike the recognized members of the genus Nonomuraea , the novel strain formed single spores at the tips of aerial hyphae. Based on the phenotypic, phylogenetic and genotypic evidence, strain PT708T represents a novel species of the genus Nonomuraea , for which the name Nonomuraea monospora sp. nov. is proposed. The type strain is PT708T ( = TISTR 1910T = JCM 16114T)
A Tuned and Scalable Fast Multipole Method as a Preeminent Algorithm for Exascale Systems
Among the algorithms that are likely to play a major role in future exascale
computing, the fast multipole method (FMM) appears as a rising star. Our
previous recent work showed scaling of an FMM on GPU clusters, with problem
sizes in the order of billions of unknowns. That work led to an extremely
parallel FMM, scaling to thousands of GPUs or tens of thousands of CPUs. This
paper reports on a a campaign of performance tuning and scalability studies
using multi-core CPUs, on the Kraken supercomputer. All kernels in the FMM were
parallelized using OpenMP, and a test using 10^7 particles randomly distributed
in a cube showed 78% efficiency on 8 threads. Tuning of the
particle-to-particle kernel using SIMD instructions resulted in 4x speed-up of
the overall algorithm on single-core tests with 10^3 - 10^7 particles. Parallel
scalability was studied in both strong and weak scaling. The strong scaling
test used 10^8 particles and resulted in 93% parallel efficiency on 2048
processes for the non-SIMD code and 54% for the SIMD-optimized code (which was
still 2x faster). The weak scaling test used 10^6 particles per process, and
resulted in 72% efficiency on 32,768 processes, with the largest calculation
taking about 40 seconds to evaluate more than 32 billion unknowns. This work
builds up evidence for our view that FMM is poised to play a leading role in
exascale computing, and we end the paper with a discussion of the features that
make it a particularly favorable algorithm for the emerging heterogeneous and
massively parallel architectural landscape
Iwasawa N=8 Attractors
Starting from the symplectic construction of the Lie algebra e_7(7) due to
Adams, we consider an Iwasawa parametrization of the coset E_7(7)/SU(8), which
is the scalar manifold of N=8, d=4 supergravity. Our approach, and the manifest
off-shell symmetry of the resulting symplectic frame, is determined by a
non-compact Cartan subalgebra of the maximal subgroup SL(8,R) of E_7(7). In
absence of gauging, we utilize the explicit expression of the Lie algebra to
study the origin of E_7(7)/SU(8) as scalar configuration of a 1/8-BPS extremal
black hole attractor. In such a framework, we highlight the action of a U(1)
symmetry spanning the dyonic 1/8-BPS attractors. Within a suitable
supersymmetry truncation allowing for the embedding of the Reissner-Nordstrom
black hole, this U(1) is interpreted as nothing but the global R-symmetry of
pure N=2 supergravity. Moreover, we find that the above mentioned U(1) symmetry
is broken down to a discrete subgroup Z_4, implying that all 1/8-BPS Iwasawa
attractors are non-dyonic near the origin of the scalar manifold. We can trace
this phenomenon back to the fact that the Cartan subalgebra of SL(8,R) used in
our construction endows the symplectic frame with a manifest off-shell
covariance which is smaller than SL(8,R) itself. Thus, the consistence of the
Adams-Iwasawa symplectic basis with the action of the U(1) symmetry gives rise
to the observed Z_4 residual non-dyonic symmetry.Comment: 1+26 page
Fast multipole networks
Two prerequisites for robotic multiagent systems are mobility and
communication. Fast multipole networks (FMNs) enable both ends within a unified
framework. FMNs can be organized very efficiently in a distributed way from
local information and are ideally suited for motion planning using artificial
potentials. We compare FMNs to conventional communication topologies, and find
that FMNs offer competitive communication performance (including higher network
efficiency per edge at marginal energy cost) in addition to advantages for
mobility
Complex joint probabilities as expressions of determinism in quantum mechanics
The density operator of a quantum state can be represented as a complex joint
probability of any two observables whose eigenstates have non-zero mutual
overlap. Transformations to a new basis set are then expressed in terms of
complex conditional probabilities that describe the fundamental relation
between precise statements about the three different observables. Since such
transformations merely change the representation of the quantum state, these
conditional probabilities provide a state-independent definition of the
deterministic relation between the outcomes of different quantum measurements.
In this paper, it is shown how classical reality emerges as an approximation to
the fundamental laws of quantum determinism expressed by complex conditional
probabilities. The quantum mechanical origin of phase spaces and trajectories
is identified and implications for the interpretation of quantum measurements
are considered. It is argued that the transformation laws of quantum
determinism provide a fundamental description of the measurement dependence of
empirical reality.Comment: 12 pages, including 1 figure, updated introduction includes
references to the historical background of complex joint probabilities and to
related work by Lars M. Johanse
Estimation of the sea surface drag coefficient based on wave data
The sea surface drag coefficient, an important parameter for the energy transfer process in wave prediction model, is generally expressed by a linear function of wind speed. However, it seems inadequate to apply these equations for strong wind conditions because these equations were deduced from the observational or the\ud
experimental data under wind speed of lower than 25m/s at fastest. To solve this problem, a wave prediction model ADWAM which includes a data assimilation method seems effective. For the purpose of clarifying the appropriate values of the sea surface drag coefficient in high wind speed, the ADWAM was modified to estimate the sea surface drag coefficients as its control variables of the model. In this study, the sea surface drag coefficient was deduced from the actual wave observation data. As a results, the sea surface drag coefficient, unknown parameter, was confirmed to\ud
be modified from arbitrary initial value to an appropriate value. Also, it was confirmed that the sea surface drag coefficient under stormy condition can be estimated based on the wave data observed outside the storm if the waves propagated from the storm were observed
Irradiation-induced Ag nanocluster nucleation in silicate glasses: analogy with photography
The synthesis of Ag nanoclusters in sodalime silicate glasses and silica was
studied by optical absorption (OA) and electron spin resonance (ESR)
experiments under both low (gamma-ray) and high (MeV ion) deposited energy
density irradiation conditions. Both types of irradiation create electrons and
holes whose density and thermal evolution - notably via their interaction with
defects - are shown to determine the clustering and growth rates of Ag
nanocrystals. We thus establish the influence of redox interactions of defects
and silver (poly)ions. The mechanisms are similar to the latent image formation
in photography: irradiation-induced photoelectrons are trapped within the glass
matrix, notably on dissolved noble metal ions and defects, which are thus
neutralized (reverse oxidation reactions are also shown to exist). Annealing
promotes metal atom diffusion, which in turn leads to cluster nuclei formation.
The cluster density depends not only on the irradiation fluence, but also - and
primarily - on the density of deposited energy and the redox properties of the
glass. Ion irradiation (i.e., large deposited energy density) is far more
effective in cluster formation, despite its lower neutralization efficiency
(from Ag+ to Ag0) as compared to gamma photon irradiation.Comment: 48 pages, 18 figures, revised version publ. in Phys. Rev. B, pdf fil
On the positive mass theorem for manifolds with corners
We study the positive mass theorem for certain non-smooth metrics following
P. Miao's work. Our approach is to smooth the metric using the Ricci flow. As
well as improving some previous results on the behaviour of the ADM mass under
the Ricci flow, we extend the analysis of the zero mass case to higher
dimensions.Comment: 21 pages, incorporated referee's comment
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