1,809 research outputs found
On the one-loop correction of "phi^4" theory in higher dimensions
We have considered phi^4 theory in higher dimensions. Using functional
diagrammatic approach, we computed the one-loop correction to effective
potential of the scalar field in five dimensions. It is shown that phi^4 theory
can be regularised in five dimensions. Temperature dependent one-loop
correction and critical temperature T_c are computed and T_c depends on the
fundamental scale M of the theory. A brief discussion of symmetry restoration
is also presented. The nature of phase transitions is examined and is of second
orderComment: 8 pages, 5 figures. To appear in IJMP
Bulk scalar field in DGP braneworld cosmology
We investigated the effects of bulk scalar field in the braneworld
cosmological scenario. The Friedmann equations and acceleration condition in
presence of the bulk scalar field for a zero tension brane and cosmological
constant are studied. In DGP model the effective Einstein equation on the brane
is obtained with bulk scalar field. The rescaled bulk scalar field on the brane
in the DGP model behaves as an effective four dimensional field, thus standard
type cosmology is recovered. In present study of the DGP model, the late-time
accelerating phase of the universe can be explained .Comment: 10 pages, to appear in JCA
Dvali-Gabadadze-Porrati Cosmology in Bianchi I brane
The dynamics of Dvali-Gabadadze-Porrati Cosmology (DGP) braneworld with an
anisotropic brane is studied. The Friedmann equations and their solutions are
obtained for two branches of anisotropic DGP model. The late time behavior in
DGP cosmology is examined in the presence of anisotropy which shows that
universe enters a self-accelerating phase much later compared to the isotropic
case. The acceleration conditions and slow-roll conditions for inflation are
obtained
A New Approach to Time Domain Classification of Broadband Noise in Gravitational Wave Data
Broadband noise in gravitational wave (GW) detectors, also known as triggers,
can often be a deterrant to the efficiency with which astrophysical search
pipelines detect sources. It is important to understand their instrumental or
environmental origin so that they could be eliminated or accounted for in the
data. Since the number of triggers is large, data mining approaches such as
clustering and classification are useful tools for this task. Classification of
triggers based on a handful of discrete properties has been done in the past. A
rich information content is available in the waveform or 'shape' of the
triggers that has had a rather restricted exploration so far. This paper
presents a new way to classify triggers deriving information from both trigger
waveforms as well as their discrete physical properties using a sequential
combination of the Longest Common Sub-Sequence (LCSS) and LCSS coupled with
Fast Time Series Evaluation (FTSE) for waveform classification and the
multidimensional hierarchical classification (MHC) analysis for the grouping
based on physical properties. A generalized k-means algorithm is used with the
LCSS (and LCSS+FTSE) for clustering the triggers using a validity measure to
determine the correct number of clusters in absence of any prior knowledge. The
results have been demonstrated by simulations and by application to a segment
of real LIGO data from the sixth science run.Comment: 16 pages, 16 figure
Sediment Distribution Analysis in Balohan Bay, Sabang
We investigated the sediment properties and distribution in Balohan Bay, which is located in southern Weh Island, Aceh Province. The aim of this research was to clarify the sediment distribution mechanism in the Balohan Bay using a statistical approach. Samples were collected on January 2016 using coring method. Sediment grain-size distribution from 14 stations was obtained using wet sieve analysis. A large amount of fine sand and very fine sand were found in Balohan Bay, as a result of several tributaries discharged in those areas. The sediment distribution in eastern stations showed an indication as a coarser size and a poorer sorted area, as they were adjacent to the steep cliff
Verification and Validation of the General Mission Analysis Tool (GMAT)
This paper describes the processes and results of Verification and Validation (V&V) efforts for the General Mission Analysis Tool (GMAT). We describe the test program and environments, the tools used for independent test data, and comparison results. The V&V effort produced approximately 13,000 test scripts that are run as part of the nightly buildtest process. In addition, we created approximately 3000 automated GUI tests that are run every two weeks. Presenting all test results are beyond the scope of a single paper. Here we present high-level test results in most areas, and detailed test results for key areas. The final product of the V&V effort presented in this paper was GMAT version R2013a, the first Gold release of the software with completely updated documentation and greatly improved quality. Release R2013a was the staging release for flight qualification performed at Goddard Space Flight Center (GSFC) ultimately resulting in GMAT version R2013b
The effect of laser repetition rate on the LASiS synthesis of biocompatible silver nanoparticles in aqueous starch solution.
Laser ablation-based nanoparticle synthesis in solution is rapidly becoming popular, particularly for potential biomedical and life science applications. This method promises one pot synthesis and concomitant bio-functionalization, is devoid of toxic chemicals, does not require complicated apparatus, can be combined with natural stabilizers, is directly biocompatible, and has high particle size uniformity. Size control and reduction is generally determined by the laser settings; that the size and size distribution scales with laser fluence is well described. Conversely, the effect of the laser repetition rate on the final nanoparticle product in laser ablation is less well-documented, especially in the presence of stabilizers. Here, the influence of the laser repetition rate during laser ablation synthesis of silver nanoparticles in the presence of starch as a stabilizer was investigated. The increment of the repetition rate does not negatively influence the ablation efficiency, but rather shows increased productivity, causes a red-shift in the plasmon resonance peak of the silver-starch nanoparticles, an increase in mean particle size and size distribution, and a distinct lack of agglomerate formation. Optimal results were achieved at 10 Hz repetition rate, with a mean particle size of ~10 nm and a bandwidth of ~6 nm 'full width at half maximum' (FWHM). Stability measurements showed no significant changes in mean particle size or agglomeration or even flocculation. However, zeta potential measurements showed that optimal double layer charge is achieved at 30 Hz. Consequently, Ag-NP synthesis via the laser ablation synthesis in solution (LASiS) method in starch solution seems to be a trade-off between small size and narrow size distributions and inherent and long-term stability
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