Random Feature Maps via a Layered Random Projection (LaRP) Framework for Object Classification

The approximation of nonlinear kernels via linear feature maps has recently gained interest due to their applications in reducing the training and testing time of kernel-based learning algorithms. Current random projection methods avoid the curse of dimensionality by embedding the nonlinear feature space into a low dimensional Euclidean space to create nonlinear kernels. We introduce a Layered Random Projection (LaRP) framework, where we model the linear kernels and nonlinearity separately for increased training efficiency. The proposed LaRP framework was assessed using the MNIST hand-written digits database and the COIL-100 object database, and showed notable improvement in object classification performance relative to other state-of-the-art random projection methods.Comment: 5 page

Bajos niveles de variación isoenzimática en las poblaciones sureñas del arbusto endémico de Corea Sophora koreensis (Fabaceae): implicaciones para su conservación

We investigated allozyme variation of the rare shrub Sophora koreensis in Yanggu County (South Korea), at the southern margin of the species range. To gain insights into ecological processes at the landscape level, we studied two or three populations from four localities (in total, 10 populations) in a range of ca. 6 km. We found low levels of within-population genetic variation (%P = 13.6, A = 1.14, and He = 0.026) and a moderate degree of among-population genetic differentiation (FST = 0.203). The analysis of molecular variance (AMOVA) revealed a substantially higher percentage of variation among populations within localities (17%) than among localities (5%). There was no significant relationship between pairwise genetic divergence and logarithm of pairwise geographic distance (r = 0.032, P = 0.842). These results suggest limited gene flow between populations within localities, while indicating that the optimal strategy for the preservation of the genetic variation of S. koreensis is to conserve as many populations as possible.Se investigó la variación isoenzimática del arbusto raro Sophora koreensis en el condado de Yanggu (Corea del Sur), en el extremo sur de su área de distribución. Para obtener información sobre los procesos ecológicos a nivel del paisaje, se estudiaron dos o tres poblaciones para cada una de las cuatro localidades (en total, 10 poblaciones) en un radio de unos 6 km. Se encontraron bajos niveles de variación genética intra-poblacional (%P = 13,6, A = 1,14 y He = 0,026) y un grado moderado de diferenciación genética entre poblaciones (FST = 0,203). El análisis de la varianza molecular (AMOVA) reveló un porcentaje sustancialmente mayor de variación entre poblaciones dentro cada una de las localidades (17%) que entre localidades (5%). No hubo una relación significativa entre la divergencia genética y el logaritmo de la distancia geográfica entre pares de poblaciones (r = 0,032, P = 0,842). Estos resultados sugieren un flujo genético limitado entre poblaciones dentro de las localidades, además de indicar que la mejor estrategia para la preservación de la diversidad genética de S. koreensis es la conservación del máximo número de poblaciones posible

Aerodynamic stability analysis of NASA J85-13/planar pressure pulse generator installation

A digital computer simulation model for the J85-13/Planar Pressure Pulse Generator (P3 G) test installation was developed by modifying an existing General Electric compression system model. This modification included the incorporation of a novel method for describing the unsteady blade lift force. This approach significantly enhanced the capability of the model to handle unsteady flows. In addition, the frequency response characteristics of the J85-13/P3G test installation were analyzed in support of selecting instrumentation locations to avoid standing wave nodes within the test apparatus and thus, low signal levels. The feasibility of employing explicit analytical expression for surge prediction was also studied

Non-equilibrium spatial distribution of Rashba spin torque in ferromagnetic metal layer

We study the spatial distribution of spin torque induced by a strong Rashba spin-orbit coupling (RSOC) in a ferromagnetic (FM) metal layer, using the Keldysh non-equilibrium Green's function method. In the presence of the s-d interaction between the non-equilibrium conduction electrons and the local magnetic moments, the RSOC effect induces a torque on the moments, which we term as the Rashba spin torque. A correlation between the Rashba spin torque and the spatial spin current is presented in this work, clearly mapping the spatial distribution of Rashba Spin torque in a nano-sized ferromagnetic device. When local magnetism is turned on, the out-of-plane (Sz) Spin Hall effect (SHE) is disrupted, but rather unexpectedly an in-plane (Sy) SHE is detected. We also study the effect of Rashba strength (\alpha_R) and splitting exchange (\Delta) on the non-equilibrium Rashba spin torque averaged over the device. Rashba spin torque allows an efficient transfer of spin momentum such that a typical switching field of 20 mT can be attained with a low current density of less than 10^6 A/cm^2

Calculation of a Class of Three-Loop Vacuum Diagrams with Two Different Mass Values

We calculate analytically a class of three-loop vacuum diagrams with two different mass values, one of which is one-third as large as the other, using the method of Chetyrkin, Misiak, and M\"{u}nz in the dimensional regularization scheme. All pole terms in \epsilon=4-D (D being the space-time dimensions in a dimensional regularization scheme) plus finite terms containing the logarithm of mass are kept in our calculation of each diagram. It is shown that three-loop effective potential calculated using three-loop integrals obtained in this paper agrees, in the large-N limit, with the overlap part of leading-order (in the large-N limit) calculation of Coleman, Jackiw, and Politzer [Phys. Rev. D {\bf 10}, 2491 (1974)].Comment: RevTex, 15 pages, 4 postscript figures, minor corrections in K(c), Appendix B removed, typos corrected, acknowledgements change

Induced Lorentz- and CPT-violating Chern-Simons term in QED: Fock-Schwinger proper time method

Using the Fock-Schwinger proper time method, we calculate the induced Chern-Simons term arising from the Lorentz- and CPT-violating sector of quantum electrodynamics with a $b_\mu \bar{\psi}\gamma^\mu \gamma_5 \psi$ term. Our result to all orders in $b$ coincides with a recent linear-in-$b$ calculation by Chaichian et al. [hep-th/0010129 v2]. The coincidence was pointed out by Chung [Phys. Lett. {\bf B461} (1999) 138] and P\'{e}rez-Victoria [Phys. Rev. Lett. {\bf 83} (1999) 2518] in the standard Feynman diagram calculation with the nonperturbative-in-$b$ propagator.Comment: 11 pages, no figur

Random Vibrational Networks and Renormalization Group

We consider the properties of vibrational dynamics on random networks, with random masses and spring constants. The localization properties of the eigenstates contrast greatly with the Laplacian case on these networks. We introduce several real-space renormalization techniques which can be used to describe this dynamics on general networks, drawing on strong disorder techniques developed for regular lattices. The renormalization group is capable of elucidating the localization properties, and provides, even for specific network instances, a fast approximation technique for determining the spectra which compares well with exact results.Comment: 4 pages, 3 figure

Thermoelectric and thermal rectification properties of quantum dot junctions

The electrical conductance, thermal conductance, thermal power and figure of merit (ZT) of semiconductor quantum dots (QDs) embedded into an insulator matrix connected with metallic electrodes are theoretically investigated in the Coulomb blockade regime. The multilevel Anderson model is used to simulate the multiple QDs junction system. The charge and heat currents in the sequential tunneling process are calculated by the Keldysh Green function technique. In the linear response regime the ZT values are still very impressive in the small tunneling rates case, although the effect of electron Coulomb interaction on ZT is significant. In the nonlinear response regime, we have demonstrated that the thermal rectification behavior can be observed for the coupled QDs system, where the very strong asymmetrical coupling between the dots and electrodes, large energy level separation between dots and strong interdot Coulomb interactions are required.Comment: 8 page and 14 figure