12,866 research outputs found
On Some Inverse Eigenvalue Problems of Quadratic Palindromic Systems
This paper concerns some inverse eigenvalue problems of the quadratic
-(anti)-palindromic system , where , ,
, is nonsingular, and the symbol is
used as an abbreviation for transpose for real matrices and either transpose or
conjugate transpose for complex matrices. By using the spectral decomposition
of the quadratic -(anti)-palindromic system, the inverse eigenvalue
problems with entire/partial eigenpairs given, and the model updating problems
with no-spillover are considered. Some conditions on the solvabilities of these
problems are given, and algorithms are proposed to find these solutions. These
algorithms are illustrated by some numerical examples
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Syntheses and characterizations of the in vivo replicative bypass and mutagenic properties of the minor-groove O2-alkylthymidine lesions.
Endogenous metabolism, environmental exposure, and treatment with some chemotherapeutic agents can all give rise to DNA alkylation, which can occur on the phosphate backbone as well as the ring nitrogen or exocyclic nitrogen and oxygen atoms of nucleobases. Previous studies showed that the minor-groove O(2)-alkylated thymidine (O(2)-alkyldT) lesions are poorly repaired and persist in mammalian tissues. In the present study, we synthesized oligodeoxyribonucleotides harboring seven O(2)-alkyldT lesions, with the alkyl group being a Me, Et, nPr, iPr, nBu, iBu or sBu, at a defined site and examined the impact of these lesions on DNA replication in Escherichia coli cells. Our results demonstrated that the replication bypass efficiencies of the O(2)-alkyldT lesions decreased with the chain length of the alkyl group, and these lesions directed promiscuous nucleotide misincorporation in E. coli cells. We also found that deficiency in Pol V, but not Pol II or Pol IV, led to a marked drop in bypass efficiencies for most O(2)-alkyldT lesions. We further showed that both Pol IV and Pol V were essential for the misincorporation of dCMP opposite these minor-groove DNA lesions, whereas only Pol V was indispensable for the T→A transversion introduced by these lesions. Depletion of Pol II, however, did not lead to any detectable alterations in mutation frequencies for any of the O(2)-alkyldT lesions. Thus, our study provided important new knowledge about the cytotoxic and mutagenic properties of the O(2)-alkyldT lesions and revealed the roles of the SOS-induced DNA polymerases in bypassing these lesions in E. coli cells
A New Counterexample to Nguyen's Conjecture on Surface Fibration
Suppose is a surface fibration of genus with
singular fibers and two of the fibers are semistable. In 1998, K. V. Nguyen
conjectured that such kind of fibration does not exist for . But in
2013, C. Gong, X. Lu, and S.-L. Tan found a counterexample to Nguyen's
conjecture for . Note that such kind of fibration shows strong arithmetic
properties, and as such the counterexamples are important, but rare in fact. In
this paper, a new counterexample to Nguyen's conjecture for is
constructed.Comment: To appear in Journal of Huzhou Universit
Abnormal Synchronizing Path of Delay-coupled Chaotic Oscillators on the Edge of Stability
In this paper, the transition of synchronizing path of delay-coupled chaotic
oscillators in a scale-free network is highlighted. Mainly, through the
critical transmission delay makes chaotic oscillators be coupled on the edge of
stability, we find that the transition of synchronizing path is
\emph{abnormal}, which is characterized by the following evidences: (a)
synchronization process starts with low-degree rather than high-degree ones;
(b) the high-degree nodes don't undertake the role of hub; (c) the synchronized
subnetworks show a poor small-world property as a result of hubs absence; (d)
the clustering synchronization behavior emerges even community structure is
absent in the scale-free network. This abnormal synchronizing path suggests
that the diverse synchronization behaviors occur in the same topology, which
implies that the relationship between dynamics and structure of network is much
more complicated than the common sense that the structure is the foundation of
dynamics. Moreover, it also reveals the potential connection from the
transition of synchronization behavior to disorder in real complex networks,
e.g. Alzheimer disease.Comment: 12 pages, 4 figure
Convolutional Low-Resolution Fine-Grained Classification
Successful fine-grained image classification methods learn subtle details
between visually similar (sub-)classes, but the problem becomes significantly
more challenging if the details are missing due to low resolution. Encouraged
by the recent success of Convolutional Neural Network (CNN) architectures in
image classification, we propose a novel resolution-aware deep model which
combines convolutional image super-resolution and convolutional fine-grained
classification into a single model in an end-to-end manner. Extensive
experiments on the Stanford Cars and Caltech-UCSD Birds 200-2011 benchmarks
demonstrate that the proposed model consistently performs better than
conventional convolutional net on classifying fine-grained object classes in
low-resolution images
Magnetogenesis in bouncing cosmology
We consider the process of magnetogenesis in the context of nonsingular
bounce cosmology. We show that large primordial magnetic fields can be
generated during contraction without encountering strong coupling and
backreaction issues. The fields may seed large-scale magnetic fields with
observationally interesting strengths. This result leads to a theoretical
constraint on the relation of the energy scale of the bounce cosmology to the
number of effective e-folding of the contracting phase in the case of scale
invariance for the power spectrum of primordial magnetic fields. We show that
this constraint can be satisfied in a sizable region of the parameter space for
the nonsingular bounce cosmology
SiMon: Simulation Monitor for Computational Astrophysics
Scientific discovery via numerical simulations is important in modern
astrophysics. This relatively new branch of astrophysics has become possible
due to the development of reliable numerical algorithms and the high
performance of modern computing technologies. These enable the analysis of
large collections of observational data and the acquisition of new data via
simulations at unprecedented accuracy and resolution. Ideally, simulations run
until they reach some pre-determined termination condition, but often other
factors cause extensive numerical approaches to break down at an earlier stage.
In those cases, processes tend to be interrupted due to unexpected events in
the software or the hardware. In those cases, the scientist handles the
interrupt manually, which is time-consuming and prone to errors. We present the
Simulation Monitor (SiMon) to automatize the farming of large and extensive
simulation processes. Our method is light-weight, it fully automates the entire
workflow management, operates concurrently across multiple platforms and can be
installed in user space. Inspired by the process of crop farming, we perceive
each simulation as a crop in the field and running simulation becomes analogous
to growing crops. With the development of SiMon we relax the technical aspects
of simulation management. The initial package was developed for extensive
parameter searchers in numerical simulations, but it turns out to work equally
well for automating the computational processing and reduction of observational
data reduction.Comment: 13 pages, 6 figures, Accepted for publication in Publications of the
Astronomical Society of the Pacific (PASP
Anomalous Magnetic Susceptibility and Hall Effect from Valley Degrees of Freedom
We study the magnetic and transport properties of epitaxial graphene films in
this letter. We predict enhanced signal of magnetic susceptibility and relate
it to the intrinsic valley magnetic moments. There is also an anomalous
contribution to the ordinary Hall effect, which is due to the valley dependent
Berry phase or valley-orbit coupling.Comment: 12 pages, 5 figure
Whether Information Network Supplements Friendship Network
Homophily is a significant mechanism for link prediction in complex network,
of which principle describes that people with similar profiles or experiences
tend to tie with each other. In a multi-relationship network, friendship among
people has been utilized to reinforce similarity of taste for recommendation
system whose basic idea is similar to homophily, yet how the taste inversely
affects friendship prediction is little discussed. This paper contributes to
address the issue by analyzing two benchmark datasets both including user's
behavioral information of taste and friendship based on the principle of
homophily. It can be found that the creation of friendship tightly associates
with personal taste. Especially, the behavioral information of taste involving
with popular objects is much more effective to improve the performance of
friendship prediction. However, this result seems to be contradictory to the
finding in [Q.M. Zhang, et al., PLoS ONE 8(2013)e62624] that the behavior
information of taste involving with popular objects is redundant in
recommendation system. We thus discuss this inconformity to comprehensively
understand the correlation between them.Comment: 8 pages, 5 figure
Community structure revealed by phase locking
Community structure can naturally emerge in paths to synchronization, and
scratching it from the paths is a tough issue that accounts for the diverse
dynamics of synchronization. In this paper, with assumption that the
synchronization on complex networks is made up of local and collective
processes, we proposed a scheme to lock the local synchronization (phase
locking) at a stable state meanwhile suppress the collective synchronization
based on Kuramoto model. Through this scheme, the network dynamics only
contains the local synchronization, which suggests that the nodes in the same
community synchronize together and these synchronization clusters well reveal
the community structure of network. Furthermore, by analyzing the paths to
synchronization, the relations or overlaps among different communities are also
obtained. Thus, the community detection based on the scheme is performed on
five real networks and the observed community structures are much more apparent
than modularity-based fast algorithm. Our results not only provide a deep
insight to understand the synchronization dynamics on complex network but also
enlarge the research scope of community detection.Comment: 8 pages, 5 figures, 2 table
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