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Search Results: 1 - 10 of 209322 matches for " George N. Jimmy "
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Preliminary Geophysical Investigation to Delineate the Groundwater Conductive Zones in the Coastal Region of Akwa Ibom State, Southern Nigeria, around the Gulf of Guinea  [PDF]
George N. Jimmy, Akpan A. Otu, Umoh A. Asuquo
International Journal of Geosciences (IJG) , 2013, DOI: 10.4236/ijg.2013.41011

This paper presents the first work of its kind within the confines of the study area. It unravels the distribution of the layers of conductive sand and their depths of interaction between freshwater from fresh sands and saltwater within the conductive layers in the coastal region of Akwa Ibom State (Nigeria) around the Gulf of Guinea. Vertical electrical sounding (VES) data whose fidelity was achieved by constraining the data by the available nearby logged borehole information during interpretation was the method applied. In the western region of the study area, the ferruginized and saline water layer is found within the depth range of 22 to 75 m deep. In the northern zone, conductive sandy layer is found within 50 to 210 m and in the eastern zone, the saline and ferruginized sandy layer is found within the depth of 88.5 m and above. Generally, the horizontal and vertical cross sections of the subsoil and the flow regime from water table depths have been delineated. With these information, water can be tapped in the area with caution and the flow direction determined can be used as input parameter in detailed contamination study.

Split Dimensional Regularization for the Coulomb Gauge
George Leibbrandt,Jimmy Williams
Physics , 1996, DOI: 10.1016/0550-3213(96)00299-4
Abstract: A new procedure for regularizing Feynman integrals in the noncovariant Coulomb gauge is proposed for Yang-Mills theory. The procedure is based on a variant of dimensional regularization, called split dimensional regularization, which leads to internally consistent, ambiguity-free integrals. It is demonstrated that split dimensional regularization yields a one-loop Yang-Mills self-energy that is nontransverse, but local. Despite the noncovariant nature of the Coulomb gauge, ghosts are necessary in order to satisfy the appropriate Ward/BRS identity. The computed Coulomb-gauge Feynman integrals are applicable to both Abelian and non-Abelian gauge models. PACS: 11.15, 12.38.C
Two-Loop Quark Self-Energy in a New Formalism: (I) Overlapping Divergences
George Leibbrandt,Jimmy Williams
Physics , 1994, DOI: 10.1016/0550-3213(94)00599-A
Abstract: A new integration technique for multi-loop Feynman integrals, called the matrix method, is developed and then applied to the divergent part of the overlapping two-loop quark self-energy function $\,i\Sigma\,$ in the light- cone gauge. It is shown that the coefficient of the double-pole term is strictly local, even off mass-shell, while the coefficient of the single-pole term contains local as well as nonlocal parts. On mass-shell, the single-pole part is local, of course. It is worth noting that the original overlapping self-energy integral reduces eventually to 10 covariant and 38 noncovariant- gauge integrals. We were able to verify explicitly that the divergent parts of the 10 double covariant-gauge integrals agreed precisely with those currently used to calculate radiative corrections in the Standard Model. Our new technique is amazingly powerful, being applicable to massive and massless integrals alike, and capable of handling both covariant-gauge integrals and the more difficult noncovariant-gauge integrals. Perhaps the most important feature of the matrix method is the ability to execute the $4\omega$-dimensional momentum integrations in a single operation, exactly and in analytic form. The method works equally well for other axial-type gauges, notably the temporal gauge ($n^2>0$) and the pure axial gauge ($n^2<0$).
Determination of Instantaneous Frequencies of Low Plasma Waves in the Magnetosheath Using Empirical Mode Decomposition (EMD) and Hilbert Transform (HT)  [PDF]
Ekong Ufot Nathaniel, Nyakno Jimmy George, Sunday Edet Etuk
Atmospheric and Climate Sciences (ACS) , 2013, DOI: 10.4236/acs.2013.34060

The observations of in-situ spacecraft mission in the magnetosheath and a region of thermalized subsonic plasma behind the bow shock reveal a non-linear behaviour of plasma waves. The study of waves and optics in Physics has given the understanding of the effect of many waves coming together to form a wave field or wave packet. The common aspect of such study shows that two or more waves can superimpose constructively or destructively. The sudden high magnetic field data in the magnetosheath displays such possibility of superposition of waves. In this paper, we use the empirical mode decomposition (EMD) and Hilbert transform (HT) techniques to determine the instantaneous frequencies of low frequency plasma waves in the magnetosheath. Our analysis has shown that the turbulent behavior of magnetic field in the magnetosheath within the selected period is due to superposition of waves.

Allowable Bearing Capacity for Shallow Foundation in Eket Local Government Area, Akwa Ibom State, Southern Nigeria  [PDF]
Joseph Gordian Atat, Idara Okon Akpabio, Nyakno Jimmy George
International Journal of Geosciences (IJG) , 2013, DOI: 10.4236/ijg.2013.410146

P-wave and S-wave velocities were obtained from seismic refraction survey in the foundation layer of Eket, the study area. The Tezcan’s approach discussed extensively in the work was used in conjunction with the existing mathematical relations between elastic parameters and seismic refraction velocities for the study of foundation layers in the study area. Based on the results, the elastic constants, allowable bearing pressure/capacity, ultimate bearing capacity and other parameters in Table 1 were determined. The result shows that allowable bearing pressure increases with increase in shear modulus and shear wave velocity. The empirical relation between allowable bearing capacity and shear modulus shows that the allowable bearing capacity increases with depth. Comparing our findings with some ranges of safe allowable bearing capacities of similar non cohesive/granular soils in literatures, the second layer with allowable bearing capacity range of 72.56 - 206.63 kN·m-2 (average = 154.78 kN·m-2) has been considered to be the safe shallow engineering foundation in the study area. The empirical relations between allowable bearing capacities shear modulus and shear wave velocity, in conjunction with the inferred maps, which serve as our findings, will be used as guide in the location of foundations. The inferred ultimate and allowable capacities correlate maximally for the two shallow foundations penetrated by the seismic waves. This perfect correlation reflects the uniqueness of the method.

Two-Loop Quark Self-Energy in a New Formalism (II): Renormalization of the Quark Propagator in the Light-Cone Gauge
George Leibbrandt,Jimmy D. Williams
Physics , 1999, DOI: 10.1016/S0550-3213(99)00666-5
Abstract: The complete two-loop correction to the quark propagator, consisting of the spider, rainbow, gluon bubble and quark bubble diagrams, is evaluated in the noncovariant light-cone gauge (lcg). (The overlapping self-energy diagram had already been computed.) The chief technical tools include the powerful matrix integration technique, the n^*-prescription for the spurious poles of 1/qn, and the detailed analysis of the boundary singularities in five- and six-dimensional parameter space. It is shown that the total divergent contribution to the two-loop correction Sigma_2 contains both covariant and noncovariant components, and is a local function of the external momentum p, even off the mass-shell, as all nonlocal divergent terms cancel exactly. Consequently, both the quark mass and field renormalizations are local. The structure of Sigma_2 implies a quark mass counterterm of the form $\delta m (lcg) = m\tilde\alpha_s C_F(3+\tilde\alpha_sW) + {\rm O} (\tilde\alpha_s^3)$, $\tilde\alpha_s = g^2\Gamma(\eps)(4\pi)^{\eps -2}$, with W depending only on the dimensional regulator epsilon, and on the numbers of colors and flavors. It turns out that \delta m(lcg) is identical to the mass counterterm in the general linear covariant gauge. Our results are in agreement with the Bassetto-Dalbosco-Soldati renormalization scheme.
Enhancement of Critical Temperature of a Striped Holographic Superconductor
Suman Ganguli,Jimmy A. Hutasoit,George Siopsis
Physics , 2012, DOI: 10.1103/PhysRevD.86.125005
Abstract: We study the interplay between the stripe order and the superconducting order in a strongly coupled striped superconductor using gauge/gravity duality. In particular, we study the effects of inhomogeneity introduced by the stripe order on the superconducting transition temperature beyond the mean field level by including the effects of backreaction onto the spacetime geometry in the dual gravitational picture. We find that inhomogeneity \emph{enhances} the critical temperature relative to its value for the uniform system.
Superconducting Dome from Holography
Suman Ganguli,Jimmy A. Hutasoit,George Siopsis
Physics , 2013, DOI: 10.1103/PhysRevD.87.126003
Abstract: We find a regime in which a strongly coupled striped superconductor features a superconducting dome. This regime is signified by i) a modulating chemical potential that averages to zero, and ii) a superconducting order parameter that has a scaling dimension larger than 3/2 but less than or equal to 3. We also find that in this regime, the order parameter exhibits a mild dependence on the modulation wavelength of the stripe.
Conductivity of Strongly Coupled Striped Superconductor
Jimmy A. Hutasoit,George Siopsis,Jason Therrien
Physics , 2012, DOI: 10.1007/JHEP01(2014)132
Abstract: We study the conductivity of a strongly coupled striped superconductor using gauge/gravity duality (holography). The study is done analytically, in the large modulation regime. We show that the optical conductivity is inhomogeneous but isotropic at low temperatures. Near but below the critical temperature, we calculate the conductivity analytically at small frequency \omega, and find it to be both inhomogeneous and anisotropic. The anisotropy is imaginary and scales like 1/\omega. We also calculate analytically the speed of the second sound and the thermodynamic susceptibility.
Metropolising forward particle filtering backward sampling and Rao-Blackwellisation of Metropolised particle smoothers
Jimmy Olsson,Tobias Rydén
Statistics , 2010,
Abstract: Smoothing in state-space models amounts to computing the conditional distribution of the latent state trajectory, given observations, or expectations of functionals of the state trajectory with respect to this distributions. For models that are not linear Gaussian or possess finite state space, smoothing distributions are in general infeasible to compute as they involve intergrals over a space of dimensionality at least equal to the number of observations. Recent years have seen an increased interest in Monte Carlo-based methods for smoothing, often involving particle filters. One such method is to approximate filter distributions with a particle filter, and then to simulate backwards on the trellis of particles using a backward kernel. We show that by supplementing this procedure with a Metropolis-Hastings step deciding whether to accept a proposed trajectory or not, one obtains a Markov chain Monte Carlo scheme whose stationary distribution is the exact smoothing distribution. We also show that in this procedure, backward sampling can be replaced by backward smoothing, which effectively means averaging over all possible trajectories. In an example we compare these approaches to a similar one recently proposed by Andrieu, Doucet and Holenstein, and show that the new methods can be more efficient in terms of precision (inverse variance) per computation time.
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