57 research outputs found
Robust extraction of text from camera images using colour and spatial information simultaneously
The importance and use of text extraction from camera based coloured scene images is rapidly increasing with time. Text within a camera grabbed image can contain a huge amount of meta data about that scene. Such meta data can be useful for identification, indexing and retrieval purposes. While the segmentation and recognition of text from document images is quite successful, detection of coloured scene text is a new challenge for all camera based images. Common problems for text extraction from camera based images are the lack of prior knowledge of any kind of text features such as colour, font, size and orientation as well as the location of the probable text regions. In this paper, we document the development of a fully automatic and extremely robust text segmentation technique that can be used for any type of camera grabbed frame be it single image or video. A new algorithm is proposed which can overcome the current problems of text segmentation. The algorithm exploits text appearance in terms of colour and spatial distribution. When the new text extraction technique was tested on a variety of camera based images it was found to out perform existing techniques (or something similar). The proposed technique also overcomes any problems that can arise due to an unconstraint complex background. The novelty in the works arises from the fact that this is the first time that colour and spatial information are used simultaneously for the purpose of text extraction
Formulation and evaluation of enteric coated microcapsules of diclofenac sodium for modified release by combination of wet granulation and thermal change method
The purpose of the present work was to develop optimized novel enteric microcapsules containing diclofenac sodium, a non steroidal anti inflammatory drug (NSAID) used for rheumatoid arthritis, for improved delivery and to diminish its adverse effect after oral administration. The microcapsule was prepared by using different polymers and the enteric coating was provided by using an innovative technique combining wet granulation method and thermal change method. This work also investigated different levels of enteric polymers like cellulose acetate phthalate (CAP) (X1) and ethyl cellulose (EC) (X2) and the stirring speed during coating ethyl cellulose (X3), by using 23 full factorial design. The dependent variables assessed were % yield (Y1), Q8 (% drug released after 8 hour) (Y2), n (Diffusion coefficient) (Y3), DEE (Drug entrapment efficiency) (Y4). The main effect and interaction terms were quantitatively evaluated using a mathematical model. The prepared microcapsules were evaluated for percentage drug dissolved, scanning electron microscopy, drug excipient interaction, angle of repose, particle size. Mean dissolution time (MDT) was used to compare dissolution patterns obtained. The results showed that X1 and X2 significantly affected the release properties
Formulation and Evaluation of Glipizide Tablets Utilizing Hibiscus Rosasinensis Leaves Mucilage
This research work aims to develop glipizide tablets using Hibiscus rosasinensis leaves mucilage. The mucilage was extracted by using double distilled water and precipitated with ethanol. The precipitated mucilage was dried and grounded into powder. The tablet utilizing the mucilage as excipient was prepared by wet granulation method. The tablets were subjected to various tests. The evaluatory parameters of tablets were found to be within the limits as per United States Pharmacopoeia NF 24/19. FTIR spectrum reveals that there is no incompatibility between the ingredients used. Diabetes was induced in wistar albino rats using streptozotocin and effect of formulation on blood glucose level was determined. It was observed that the formulation could not sustain the release of glipizide. However, the glipizide release was retarded as the amount of mucilage was increased. It was observed that on the completion of antidiabetic study, the formulation could bring the blood glucose level to normal in group rats. However, the blood glucose level was still elevated in group administered with pure gliplizide. It can be concluded that HRM can be used to formulate glipizide tablets. The formulations with HRM shows better hypoglycemic activity and this may be attributed to antidiabetic activity of Hibiscus rosasinensis.
To freeze or not to: Quantum correlations under local decoherence
We provide necessary and sufficient conditions for freezing of quantum
correlations as measured by quantum discord and quantum work deficit in the
case of bipartite as well as multipartite states subjected to local noisy
channels. We recognize that inhomogeneity of the magnetizations of the shared
quantum states plays an important role in the freezing phenomena. We show that
the frozen value of the quantum correlation and the time interval for freezing
follow a complementarity relation. For states which do not exhibit "exact"
freezing, but can be frozen "effectively", by having a very slow decay rate
with suitable tuning of the state parameters, we introduce an index -- the
freezing index -- to quantify the goodness of freezing. We find that the
freezing index can be used to detect quantum phase transitions and discuss the
corresponding scaling behavior.Comment: 14 pages, 9 figures, close to published version, title changed by
Phys. Rev. A. to 'Freezing of quantum correlations under local decoherence
Scale-invariant freezing of entanglement
We show that bipartite entanglement in a one-dimensional quantum spin model
undergoing time-evolution under local Markovian environments can be frozen over
time. We demonstrate this by using a number of paradigmatic quantum spin models
in one dimension, including the anisotropic XY model in the presence of a
uniform and an alternating transverse magnetic field (ATXY), the XXZ model, the
XYZ model, and the model involving the next-nearest-neighbor
interactions. We show that the length of the freezing interval, for a chosen
pair of nearest-neighbor spins, may remain independent of the length of the
spin-chain, for example, in paramagnetic phases of the ATXY model, indicating a
scale-invariance. Such freezing of entanglement is found to be robust against a
change in the environment temperature, presence of disorder in the system, and
whether the noise is dissipative, or not dissipative. Moreover, we connect the
freezing of entanglement with the propagation of information through a quantum
many-body system, as considered in the Lieb-Robinson theorem. We demonstrate
that the variation of the freezing duration exhibits a quadratic behavior
against the distance of the nearest-neighbor spin-pair from the noise-source,
obtained from exact numerical simulations, in contrast to the linear one as
predicted by the Lieb-Robinson theorem.Comment: 13 pages, 6 figures, close to published versio
Emergence of entanglement with temperature and time in factorization-surface states
There exist zero-temperature states in quantum many-body systems that are
fully factorized, thereby possessing vanishing entanglement, and hence being of
no use as resource in quantum information processing tasks. Such states can
become useful for quantum protocols when the temperature of the system is
increased, and when the system is allowed to evolve under either the influence
of an external environment, or a closed unitary evolution driven by its own
Hamiltonian due to a sudden change in the system parameters. Using the
one-dimensional anisotropic XY model in a uniform and an alternating transverse
magnetic field, we show that entanglement of the thermal states, corresponding
to the factorization points in the space of the system parameters, revives once
or twice with increasing temperature. We also study the closed unitary
evolution of the quantum spin chain driven out of equilibrium when the external
magnetic fields are turned off, and show that considerable entanglement is
generated during the dynamics, when the initial state has vanishing
entanglement. Interestingly, we find that creation of entanglement for a pair
of spins is possible when the system is made open to an external heat bath,
interacting through that spin-pair having a repetitive quantum interaction.Comment: 10 pages, 6 figures, close to published versio
Static and dynamical quantum correlations in phases of an alternating field XY model
We investigate the static and dynamical patterns of entanglement in an
anisotropic XY model with an alternating transverse magnetic field, which is
equivalent to a two-component one-dimensional Fermi gas on a lattice, a system
realizable with current technology. Apart from the antiferromagnetic and
paramagnetic phases, the model possesses a dimer phase which is not present in
the transverse XY model. At zero temperature, we find that the first derivative
of bipartite entanglement can detect all the three phases. We analytically show
that the model has a "factorization line" on the plane of system parameters, in
which the zero temperature state is separable. Along with investigating the
effect of temperature on entanglement in a phase plane, we also report a
non-monotonic behavior of entanglement with respect to temperature in the
anti-ferromagnetic and paramagnetic phases, which is surprisingly absent in the
dimer phase. Since the time dynamics of entanglement in a realizable physical
system plays an important role in quantum information processing tasks, the
evolutions of entanglement at small as well as large time are examined.
Consideration of large time behavior of entanglement helps us to prove that in
this model, entanglement is always ergodic. We observe that other quantum
correlation measures can qualitatively show similar features in zero and finite
temperatures. However, unlike nearest-neighbor entanglement, the
nearest-neighbor information theoretic measures can be both ergodic as well as
non-ergodic, depending on the system parameters.Comment: 20 Pages, 13 Figures, 2 Tables, Published versio
Reducing Computational Complexity of Quantum Correlations
We address the issue of reducing the resource required to compute
information-theoretic quantum correlation measures like quantum discord and
quantum work deficit in two qubits and higher dimensional systems. We show that
determination of the quantum correlation measure is possible even if we utilize
a restricted set of local measurements. We find that the determination allows
us to obtain a closed form of quantum discord and quantum work deficit for
several classes of states, with a low error. We show that the computational
error caused by the constraint over the complete set of local measurements
reduces fast with an increase in the size of the restricted set, implying
usefulness of constrained optimization, especially with the increase of
dimensions. We perform quantitative analysis to investigate how the error
scales with the system size, taking into account a set of plausible
constructions of the constrained set. Carrying out a comparative study, we show
that the resource required to optimize quantum work deficit is usually higher
than that required for quantum discord. We also demonstrate that minimization
of quantum discord and quantum work deficit is easier in the case of two-qubit
mixed states of fixed ranks and with positive partial transpose in comparison
to the corresponding states having non-positive partial transpose. Applying the
methodology to quantum spin models, we show that the constrained optimization
can be used with advantage in analyzing such systems in quantum
information-theoretic language. For bound entangled states, we show that the
error is significantly low when the measurements correspond to the spin
observables along the three Cartesian coordinates, and thereby we obtain
expressions of quantum discord and quantum work deficit for these bound
entangled states.Comment: 19 pages, 14 figures, 3 table
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