362 research outputs found
Epidemiological Insights of Foot and Mouth Disease Virus Infection among Cattle and Buffaloes in Sharkia Governorate, Egypt
Foot-and-mouth disease (FMD) is endemic in Egypt and in most parts of Africa causing huge economic losses. Control of FMD using vaccination requires information on the occurrence of various FMDV serotypes. This study aimed to determine the prevalence of FMDV serotypes in Sharkia Governorate, Egypt. A total number of 643 different samples, within ten different localities, were collected from both cattle and buffaloes (n = 283) of different, age, sex, immune status against FMD, and health status. Field samples (n = 360) have been screened for FMDV by RT-PCR using universal primers and were further subtyped using serotype-specific primers. Additionally, serum samples (n = 283) have been analyzed by applying FMDV serotype-specific antibody ELISA. The RT-PCR screening revealed that a total number of 39/283 (13.8%), 61/283 (21.6%) and 17/38 (44.7%) animals were positive for FMDV serotype O, A and SAT2, respectively. While, by ELISA, neutralizing antibodies directed against FMDV serotype O, A, and SAT2, were found in 177/283 (62.5%), 171/283 (60.4%) and 27/38 (71.1%) serum samples, respectively. These results indicated the endemic status of the FMDV serotypes O, A and SAT2 in Sharkia Governorate despite routine FMD vaccination programs. Although many variations of disease prevalence were recorded between animals of different, age, sex and immune and health status but it was obvious that FMD was more prominent and prevalent in buffaloes (47.1%) than in cattle (34.1%). Therefore, control efforts should focus on reducing the circulation of FMDV among susceptible livestock with special attention towards water buffaloes. Continuous surveillance, at molecular and immunological levels, of FMDV serotypes is needed for the effectiveness of any adopted control strategy targeting FMD including vaccination
Quantum Holography
We propose to make use of quantum entanglement for extracting holographic
information about a remote 3-D object in a confined space which light enters,
but from which it cannot escape. Light scattered from the object is detected in
this confined space entirely without the benefit of spatial resolution. Quantum
holography offers this possibility by virtue of the fourth-order quantum
coherence inherent in entangled beams.Comment: 7 pages, submitted to Optics Expres
Synthesis and Analysis of Entangled Photonic Qubits in Spatial-Parity Space
We present the novel embodiment of a photonic qubit that makes use of one
continuous spatial degree of freedom of a single photon and relies on the the
parity of the photon's transverse spatial distribution. Using optical
spontaneous parametric downconversion to produce photon pairs, we demonstrate
the controlled generation of entangled-photon states in this new space.
Specifically, two Bell states, and a continuum of their superpositions, are
generated by simple manipulation of a classical parameter, the optical-pump
spatial parity, and not by manipulation of the entangled photons themselves. An
interferometric device, isomorphic in action to a polarizing beam splitter,
projects the spatial-parity states onto an even--odd basis. This new physical
realization of photonic qubits could be used as a foundation for future
experiments in quantum information processing.Comment: 6 pages, 5 figures, submitted to PR
Interferometric control of the photon-number distribution
We demonstrate deterministic control over the photon-number distribution by
interfering two coherent beams within a disordered photonic lattice. By
sweeping a relative phase between two equal-amplitude coherent fields with
Poissonian statistics that excite adjacent sites in a lattice endowed with
disorder-immune chiral symmetry, we measure an output photon-number
distribution that changes periodically between super-thermal and sub-thermal
photon statistics upon ensemble averaging. Thus, the photon-bunching level is
controlled interferometrically at a fixed mean photon-number by gradually
activating the excitation symmetry of the chiral-mode pairs with structured
coherent illumination and without modifying the disorder level of the random
system itself
Experimental Violation of Bell's Inequality in Spatial-Parity Space
We report the first experimental violation of Bell's inequality in the
spatial domain using the Einstein--Podolsky--Rosen state. Two-photon states
generated via optical spontaneous parametric downconversion are shown to be
entangled in the parity of their one-dimensional transverse spatial profile.
Superpositions of Bell states are prepared by manipulation of the optical
pump's transverse spatial parity--a classical parameter. The Bell-operator
measurements are made possible by devising simple optical arrangements that
perform rotations in the one-dimensional spatial-parity space of each photon of
an entangled pair and projective measurements onto a basis of even--odd
functions. A Bell-operator value of 2.389 +- 0.016 is recorded, a violation of
the inequality by more than 24 standard deviations.Comment: 10 pages, 3 figures, 1 Tabl
Ellipsometric measurements by use of photon pairs generated by spontaneous parametric down-conversion
We present a novel interferometric technique for performing ellipsometric
measurements. This technique relies on the use of a non-classical optical
source, namely, polarization-entangled twin photons generated by spontaneous
parametric down-conversion from a nonlinear crystal, in conjunction with a
coincidence-detection scheme. Ellipsometric measurements acquired with this
scheme are absolute; i.e., they do not require source and detector calibration.Comment: 10 pages, accepted for publication in Optics Letter
Fair resource allocation with interference mitigation and resource reuse for LTE/LTE-A femtocell networks
Joint consideration of interference, resource utilization, fairness, and complexity issues is generally lacking in existing resource allocation schemes for Long-Term Evolution (LTE)/LTE-Advanced femtocell networks. To tackle this, we employ a hybrid spectrum allocation approach whereby the spectrum is split between the macrocell and its nearby interfering femtocells based on their resource demands, whereas the distant femtocells share the entire spectrum. A multiobjective problem is formulated for resource allocation between femtocells and is decomposed using a lexicographic optimization approach into two subproblems. A greedy algorithm of reasonably low complexity is proposed to solve these subproblems sequentially. Simulation results show that the proposed scheme achieves substantial throughput and packet loss improvements in low-density femtocell deployment scenarios while performing satisfactorily in high-density femtocell deployment scenarios with substantial complexity and overhead reduction. The proposed scheme also performs nearly as well as the optimal solution obtained by exhaustive search
Multi-objective resource allocation for LTE/LTE-A femtocell/HeNB networks using ant colony optimization
Existing femtocell resource allocation schemes for Long Term Evolution or LTE-Advanced femtocell networks do not jointly achieve efficient resource utilization, fairness guarantee, interference mitigation and reduced complexity in a satisfactory manner. In this paper, a multi-objective resource allocation scheme is proposed to achieve these desired features simultaneously. We first formulate three objective functions to respectively maximize resource utilization efficiency, guarantee a high degree of fairness and minimize interference. A weighted sum approach is then used to combine these objective functions to form a single multi-objective optimization problem. An ant colony optimization algorithm is employed to find the Pareto-optimal solution to this problem. Simulation results demonstrate that the proposed scheme performs jointly well in all aspects, namely resource utilization, fairness and interference mitigation. Additionally, it maintains satisfactory performance in the handover process and has a reasonably low complexity compared to the existing schemes
Single-photon three-qubit quantum logic using spatial light modulators
The information-carrying capacity of a single photon can be vastly expanded by exploiting its multiple degrees of freedom: spatial, temporal, and polarization. Although multiple qubits can be encoded per photon, to date only two-qubit single-photon quantum operations have been realized. Here, we report an experimental demonstration of three-qubit single-photon, linear, deterministic quantum gates that exploit photon polarization and the two-dimensional spatial-parity-symmetry of the transverse single-photon field. These gates are implemented using a polarization-sensitive spatial light modulator that provides a robust, non-interferometric, versatile platform for implementing controlled unitary gates. Polarization here represents the control qubit for either separable or entangling unitary operations on the two spatial-parity target qubits. Such gates help generate maximally entangled three-qubit Greenberger–Horne–Zeilinger and W states, which is confirmed by tomographical reconstruction of single-photon density matrices. This strategy provides access to a wide range of three-qubit states and operations for use in few-qubit quantum information processing protocols
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