5,492 research outputs found
Resource efficient redundancy using quorum-based cycle routing in optical networks
In this paper we propose a cycle redundancy technique that provides optical
networks almost fault-tolerant point-to-point and multipoint-to-multipoint
communications. The technique more importantly is shown to approximately halve
the necessary light-trail resources in the network while maintaining the
fault-tolerance and dependability expected from cycle-based routing. For
efficiency and distributed control, it is common in distributed systems and
algorithms to group nodes into intersecting sets referred to as quorum sets.
Optimal communication quorum sets forming optical cycles based on light-trails
have been shown to flexibly and efficiently route both point-to-point and
multipoint-to-multipoint traffic requests. Commonly cycle routing techniques
will use pairs of cycles to achieve both routing and fault-tolerance, which
uses substantial resources and creates the potential for underutilization.
Instead, we intentionally utilize redundancy within the quorum cycles for
fault-tolerance such that almost every point-to-point communication occurs in
more than one cycle. The result is a set of cycles with 96.60% - 99.37% fault
coverage, while using 42.9% - 47.18% fewer resources.Comment: 17th International Conference on Transparent Optical Networks
(ICTON), 5-9 July 2015. arXiv admin note: substantial text overlap with
arXiv:1608.05172, arXiv:1608.0516
Unidirectional Quorum-based Cycle Planning for Efficient Resource Utilization and Fault-Tolerance
In this paper, we propose a greedy cycle direction heuristic to improve the
generalized redundancy quorum cycle technique. When applied using
only single cycles rather than the standard paired cycles, the generalized
redundancy technique has been shown to almost halve the necessary
light-trail resources in the network. Our greedy heuristic improves this
cycle-based routing technique's fault-tolerance and dependability.
For efficiency and distributed control, it is common in distributed systems
and algorithms to group nodes into intersecting sets referred to as quorum
sets. Optimal communication quorum sets forming optical cycles based on
light-trails have been shown to flexibly and efficiently route both
point-to-point and multipoint-to-multipoint traffic requests. Commonly cycle
routing techniques will use pairs of cycles to achieve both routing and
fault-tolerance, which uses substantial resources and creates the potential for
underutilization. Instead, we use a single cycle and intentionally utilize
redundancy within the quorum cycles such that every point-to-point
communication pairs occur in at least cycles. Without the paired
cycles the direction of the quorum cycles becomes critical to the fault
tolerance performance. For this we developed a greedy cycle direction heuristic
and our single fault network simulations show a reduction of missing pairs by
greater than 30%, which translates to significant improvements in fault
coverage.Comment: Computer Communication and Networks (ICCCN), 2016 25th International
Conference on. arXiv admin note: substantial text overlap with
arXiv:1608.05172, arXiv:1608.05168, arXiv:1608.0517
Generic bounds on dipolar gravitational radiation from inspiralling compact binaries
Various alternative theories of gravity predict dipolar gravitational
radiation in addition to quadrupolar radiation. We show that gravitational wave
(GW) observations of inspiralling compact binaries can put interesting
constraints on the strengths of the dipole modes of GW polarizations. We put
forward a physically motivated gravitational waveform for dipole modes, in the
Fourier domain, in terms of two parameters: one which captures the relative
amplitude of the dipole mode with respect to the quadrupole mode () and
the other a dipole term in the phase (). We then use this two parameter
representation to discuss typical bounds on their values using GW measurements.
We obtain the expected bounds on the amplitude parameter and the phase
parameter for Advanced LIGO (AdvLIGO) and Einstein Telescope (ET) noise
power spectral densities using Fisher information matrix. AdvLIGO and ET may at
best bound to an accuracy of and and
to an accuracy of and respectively.Comment: Matches with the published versio
Testing post-Newtonian theory with gravitational wave observations
The Laser Interferometric Space Antenna (LISA) will observe supermassive
black hole binary mergers with amplitude signal-to-noise ratio of several
thousands. We investigate the extent to which such observations afford
high-precision tests of Einstein's gravity. We show that LISA provides a unique
opportunity to probe the non-linear structure of post-Newtonian theory both in
the context of general relativity and its alternatives.Comment: 9 pages, 2 figure
EVALUATION OF ANTIDIABETIC ACTIVITY OF ZANTHOXYLUM OVALIFOLIUM LEAF EXTRACTS
Objective: The present study was aimed to investigate the antidiabetic activity of ethanolic and aqueous extract of Zanthoxylum ovalifolium on alloxan induced diabetic rat model in rats.
Methods: The leaves of Zanthoxylum ovalifolium were evaluated for antidiabetic activity by using alloxan induced diabetic model in diabetic rats. Diabetes was induced by single intraperitoneal injection of alloxan (100 mg/kg) and rats were treated orally with test extracts, standard drug (glibenclamide 5 mg/kg) and vehicle for 21 d. The hypoglycemic effects and lipid profile of diabetic rats were assessed using diagnostic kits. Finally, histopathological studies were carried out for pancreas.
Results: The acute toxicity studies revealed at the dose of 2000 mg/kg (b. w) of Zanthoxylum ovalifolium for ethanol and aqueous extract were found to be safe. A significant reduction (p<0.001) in blood glucose was observed in diabetic rats treated with different doses of extracts compared to untreated diabetic rats. The drug possesses a good hyperlipidemic effect by normalizing the lipid parameters. This was evidenced by histopathological studies; both glibenclamide and 400 mg/kg of Ethanolic extract does appear to be regulated diabetes at the cellular level, resulting in the restoration of near normal architecture pancreatic islet of langerhans.
Conclusion: It can be concluded from our research findings that ethanolic and aqueous extract of Zanthoxylum ovalifoliumat high dose (400 mg/kg) exhibited significant antihyperglycemic activity than extract at low dose (200 mg/kg) in alloxan induced diabetic rats. These extracts also showed improvement in parameters like lipid profile as well as regeneration β-cells in the pancreas and so might be of value in diabetes treatment
Spacecraft Attitude Determination Using Ground Based Photometry: A Comparison of Estimation Algorithms
The time history of ground-based photometry measurements, called lightcurves, can be used to determine the attitude of a spacecraft. The extraction of information about the satellite’s attitude is realized through what is called lightcurve inversion. Lightcurve inversion utilizes a filter or an optimization method to extract the information on the desired parameters. The accuracy of the lightcurve inversion performance of three filters is compared. These filters are the bootstrap particle filter, the extended Kalman filter and the unscented Kalman filter. The attitude modes of a controlled spacecraft maintaining an inertially fixed attitude and spinning at constant rates are simulated. When the spacecraft is maintaining its inertial attitude, none of the filters are able to accurately estimate the satellite attitude. However, when the spacecraft was rotating the filterswere able to estimate the attitude for varying degrees of initial conditions. The extended Kalman filter performs as well as the other two filters when the initial attitude uncertainty is low. When the initial attitude uncertainty increases to high levels, the bootstrap particle filter is the only filter able to accurately determine the spacecraft attitude
Inspiralling compact binaries in quasi-elliptical orbits: The complete third post-Newtonian energy flux
The instantaneous contributions to the 3PN gravitational wave luminosity from
the inspiral phase of a binary system of compact objects moving in a quasi
elliptical orbit is computed using the multipolar post-Minkowskian wave
generation formalism. The necessary inputs for this calculation include the 3PN
accurate mass quadrupole moment for general orbits and the mass octupole and
current quadrupole moments at 2PN. Using the recently obtained 3PN
quasi-Keplerian representation of elliptical orbits the flux is averaged over
the binary's orbit. Supplementing this by the important hereditary
contributions arising from tails, tails-of-tails and tails squared terms
calculated in a previous paper, the complete 3PN energy flux is obtained. The
final result presented in this paper would be needed for the construction of
ready-to-use templates for binaries moving on non-circular orbits, a plausible
class of sources not only for the space based detectors like LISA but also for
the ground based ones.Comment: 40 pages. Minor changes in text throughout. Minor typos in Eqs.
(3.3b), (7.7f), (8.19d) and (8.20) corrected. Matches the published versio
MDR1 siRNA loaded hyaluronic acid-based CD44 targeted nanoparticle systems circumvent paclitaxel resistance in ovarian cancer.
Development of multidrug resistance (MDR) is an almost universal phenomenon in patients with ovarian cancer, and this severely limits the ultimate success of chemotherapy in the clinic. Overexpression of the MDR1 gene and corresponding P-glycoprotein (Pgp) is one of the best known MDR mechanisms. MDR1 siRNA based strategies were proposed to circumvent MDR, however, systemic, safe, and effective targeted delivery is still a major challenge. Cluster of differentiation 44 (CD44) targeted hyaluronic acid (HA) based nanoparticle has been shown to successfully deliver chemotherapy agents or siRNAs into tumor cells. The goal of this study is to evaluate the ability of HA-PEI/HA-PEG to deliver MDR1 siRNA and the efficacy of the combination of HA-PEI/HA-PEG/MDR1 siRNA with paclitaxel to suppress growth of ovarian cancer. We observed that HA-PEI/HA-PEG nanoparticles can efficiently deliver MDR1 siRNA into MDR ovarian cancer cells, resulting in down-regulation of MDR1 and Pgp expression. Administration of HA-PEI/HA-PEG/MDR1 siRNA nanoparticles followed by paclitaxel treatment induced a significant inhibitory effect on the tumor growth, decreased Pgp expression and increased apoptosis in MDR ovarian cancer mice model. Our findings suggest that CD44 targeted HA-PEI/HA-PEG/MDR1 siRNA nanoparticles can serve as a therapeutic tool with great potentials to circumvent MDR in ovarian cancer
Progress Toward National Aeronautics Goals
NASA has made definitive progress towards achieving several bold U.S. goals in aeronautics related to air breathing engines. The advanced technologies developed towards these goals span applications from general aviation to large subsonic and supersonic aircraft. The proof of successful technology development is demonstrated through successful technology transfer to U.S. industry and projected fleet impact. Specific examples of progress are discussed that quantifies the achievement towards these goals. In addition, a more detailed vision for NASA aeronautics is defined and key strategic issues are explored which invite international and national debate and involvement especially in reduced environmental impact for subsonic and supersonic aircraft, dramatic new capabilities in general aviation engines, and reduced development cycle time and costs
Role of immunoturbidimetric plasma fibrin D-dimer test in patients with coronary artery disease as well as ischemic heart disease in emergency medicine
The aim of the present was to assess the value of the ELISA D-dimer (hemostatic marker) assay in patients with coronary artery disease as well as ischemic heart disease presenting to the emergency department with chest pain syndrome. Methods: We measured levels of D-dimers (µg/ml by immunoturbidimetric assay) in 120 patients with angiographically proved CAD, consecutive outpatients with chest pain, arterial fibrillation, acute coronary syndromes and 240 age and sex matched healthy controls. Demographic characteristics were assessed by a standardized questionnaire, and a complete lipid profile was performed for all subjects. In addition to this inflammatory marker C- reactive protein was also measured. Result: The distribution of D-dimer levels skewed to the right, and plasma mean levels were higher in cases than in control (mean: 2.51±3.60 vs .41±.59 µg/ml; p<0.001). In contrast, correlation of D-dimer was found with C-reactive protein (p<0.001) and is higher in cases than controls. Conclusion: Plasma D-dimer levels are strongly and independently associated with the presence of CAD in patients with stable angina. These results support the concept of a contribution of intravascular fibrin to atherothrombogenesis
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