1,784 research outputs found
Comment on "Fermionic entanglement ambiguity in noninertial frames"
In this comment we show that the ambiguity of entropic quantities calculated
in Physical Review A 83, 062323 (2011) for fermionic fields in the context of
Unruh effect is not related to the properties of anticommuting fields, as
claimed in Physical Review A 83, 062323 (2011), but rather to wrong
mathematical manipulations with them and not taking into account a fundamental
superselection rule of quantum field theory.Comment: To appear in Physical Review A. Some of the problems discussed in
this comment can also be found in other previously published papers studying
the Unruh effect for fermions (in the context of quantum information theory).
An extended version of the comment can be found here
http://arxiv.org/abs/1108.555
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UPC++ v1.0 Programmer’s Guide, Revision 2020.3.0
UPC++ is a C++11 library that provides Partitioned Global Address Space (PGAS) programming. It is designed for writing parallel programs that run efficiently and scale well on distributed-memory parallel computers. The PGAS model is single program, multiple-data (SPMD), with each separate constituent process having access to local memory as it would in C++. However, PGAS also provides access to a global address space, which is allocated in shared segments that are distributed over the processes. UPC++ provides numerous methods for accessing and using global memory. In UPC++, all operations that access remote memory are explicit, which encourages programmers to be aware of the cost of communication and data movement. Moreover, all remote-memory access operations are by default asynchronous, to enable programmers to write code that scales well even on hundreds of thousands of cores
Computational and experimental analyses of retrotransposon-associated minisatellite DNAs in the soybean genome
BACKGROUND:
Retrotransposons are mobile DNA elements that spread through genomes via the action of element-encoded reverse transcriptases. They are ubiquitous constituents of most eukaryotic genomes, especially those of higher plants. The pericentromeric regions of soybean (Glycine max) chromosomes contain \u3e3,200 intact copies of the Gmr9/GmOgre retrotransposon. Between the 3\u27 end of the coding region and the long terminal repeat, this retrotransposon family contains a polymorphic minisatellite region composed of five distinct, interleaved minisatellite families. To better understand the possible role and origin of retrotransposon-associated minisatellites, a computational project to map and physically characterize all members of these families in the G. max genome, irrespective of their association with Gmr9, was undertaken. METHODS:
A computational pipeline was developed to map and analyze the organization and distribution of five Gmr9-associated minisatellites throughout the soybean genome. Polymerase chain reaction amplifications were used to experimentally assess the computational outputs. RESULTS:
A total of 63,841 copies of Gmr9-associated minisatellites were recovered from the assembled G. max genome. Ninety percent were associated with Gmr9, an additional 9% with other annotated retrotransposons, and 1% with uncharacterized repetitive DNAs. Monomers were tandemly interleaved and repeated up to 149 times per locus. CONCLUSIONS:
The computational pipeline enabled a fast, accurate, and detailed characterization of known minisatellites in a large, downloaded DNA database, and PCR amplification supported the general organization of these arrays
Regular and chaotic states in a local map description of sheared nematic liquid crystals
We propose and study a local map capable of describing the full variety of dynamical states, ranging from regular to chaotic, obtained when a nematic liquid crystal is subjected to a steady shear flow. The map is formulated in terms of a quaternion parametrization of rotations of the local frame described by the axes of the nematic director, subdirector, and the joint normal to these, with two additional scalars describing the strength of ordering. Our model yields kayaking, wagging, tumbling, aligned, and coexistence states, accommodated in a phase diagram which closely resembles phase diagrams obtained using representations of the dynamics which are based on ordinary differential equations. We also study the behavior of the map under periodic perturbations of the shear rate. Such a map can serve as a building block for the construction of lattice models of the complex spatiotemporal states predicted for sheared nematics
A Coupled Map Lattice Model for Rheological Chaos in Sheared Nematic Liquid Crystals
A variety of complex fluids under shear exhibit complex spatio-temporal
behaviour, including what is now termed rheological chaos, at moderate values
of the shear rate. Such chaos associated with rheological response occurs in
regimes where the Reynolds number is very small. It must thus arise as a
consequence of the coupling of the flow to internal structural variables
describing the local state of the fluid. We propose a coupled map lattice (CML)
model for such complex spatio-temporal behaviour in a passively sheared nematic
liquid crystal, using local maps constructed so as to accurately describe the
spatially homogeneous case. Such local maps are coupled diffusively to nearest
and next nearest neighbours to mimic the effects of spatial gradients in the
underlying equations of motion. We investigate the dynamical steady states
obtained as parameters in the map and the strength of the spatial coupling are
varied, studying local temporal properties at a single site as well as
spatio-temporal features of the extended system. Our methods reproduce the full
range of spatio-temporal behaviour seen in earlier one-dimensional studies
based on partial differential equations. We report results for both the one and
two-dimensional cases, showing that spatial coupling favours uniform or
periodically time-varying states, as intuitively expected. We demonstrate and
characterize regimes of spatio-temporal intermittency out of which chaos
develops. Our work suggests that such simplified lattice representations of the
spatio-temporal dynamics of complex fluids under shear may provide useful
insights as well as fast and numerically tractable alternatives to continuum
representations.Comment: 32 pages, single column, 20 figure
Capacities of Grassmann channels
A new class of quantum channels called Grassmann channels is introduced and
their classical and quantum capacity is calculated. The channel class appears
in a study of the two-mode squeezing operator constructed from operators
satisfying the fermionic algebra. We compare Grassmann channels with the
channels induced by the bosonic two-mode squeezing operator. Among other
results, we challenge the relevance of calculating entanglement measures to
assess or compare the ability of bosonic and fermionic states to send quantum
information to uniformly accelerated frames.Comment: 33 pages, Accepted in Journal of Mathematical Physics; The role of
the (fermionic) braided tensor product for quantum Shannon theory, namely
capacity formulas, elucidated; The conclusion on the equivalence of Unruh
effect for bosons and fermions for quantum communication purposes made clear
and even more precis
Dephasing of a Qubit due to Quantum and Classical Noise
The qubit (or a system of two quantum dots) has become a standard paradigm
for studying quantum information processes. Our focus is Decoherence due to
interaction of the qubit with its environment, leading to noise. We consider
quantum noise generated by a dissipative quantum bath. A detailed comparative
study with the results for a classical noise source such as generated by a
telegraph process, enables us to set limits on the applicability of this
process vis a vis its quantum counterpart, as well as lend handle on the
parameters that can be tuned for analyzing decoherence. Both Ohmic and
non-Ohmic dissipations are treated and appropriate limits are analyzed for
facilitating comparison with the telegraph process.Comment: 12 pages, 8 figure
Continuous variable private quantum channel
In this paper we introduce the concept of quantum private channel within the
continuous variables framework (CVPQC) and investigate its properties. In terms
of CVPQC we naturally define a "maximally" mixed state in phase space together
with its explicit construction and show that for increasing number of
encryption operations (which sets the length of a shared key between Alice and
Bob) the encrypted state is arbitrarily close to the maximally mixed state in
the sense of the Hilbert-Schmidt distance. We bring the exact solution for the
distance dependence and give also a rough estimate of the necessary number of
bits of the shared secret key (i.e. how much classical resources are needed for
an approximate encryption of a generally unknown continuous-variable state).
The definition of the CVPQC is analyzed from the Holevo bound point of view
which determines an upper bound of information about an incoming state an
eavesdropper is able to get from his optimal measurement.Comment: upper bound on information Eve can get was revised and substantially
lowered (chapter IV), part of chapter III rewritten, several typos correcte
Exploratory Study of Visual Enhancement to Display Smart Apps on Android Phones for Selasar Imaji Library
The attractive appearance of the system applications on the Android phone is quite important. There is an initial premise that the "Imaji Library" application that the Selasar Imaji Library owns is less attractive to users because it is not attractive. This study aims to explore an attractive appearance based on studies that are filtered to application users. Through Research and Development (R&D) activities, by 1) capturing questionnaire results from users to find out what is less attractive from the application display; 2) study of the search for the preferred visual appearance; 3) designing applications; and 4) application testing to librarians. The results of the exploration activities are in the form of (1) a new prototype design of the "Imaji Library" application display, (2) the development of application features in terms of procurement, processing, tracking, and member and circulation management activities. The implication of this research is helpful for librarians' convenience in managing libraries
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