Moment-based fast discrete sine transforms

This paper presents a novel approach to compute discrete sine transforms (DSTs). By using a modular mapping, DSTs are approximated by the sum of a finite sequence of discrete moments. Hence, by extending our earlier technique in computing moments with an adder network only, DSTs can also be implemented easily by a systolic array primarily involving additions. The method can be applied to multidimensional DSTs as well as their inverses.published_or_final_versio

A novel approach to fast discrete Hartley transform

The Discrete Hartley transform (DHT) is an important tool in digital signal processing. We propose a novel approach to perform DHT. We transform DHT into a form expressed in discrete moments via a modular mapping and truncating Taylor series expansion and present a completely new formula for computing DHT. We extend the use of our systolic array for fast computation of moments without any multiplications, to one that computes DHT with only a few multiplications and without any evaluations of triangular functions. The multiplication number used in our method is O(Nlog2N/log2log2N) superior to O(Nlog 2N) in the conventional FDT. The execution time of the systolic array is only O(Nlog2N/log2log2N) for 1-D DHT and O(N k) for k-D DHT (k⩾2). The systolic array consists of very simple processing elements and hence it implies an easy and potential hardware/VLSI implementation. The approach is also applicable to DHT inverses.published_or_final_versio

Fast tracking of evoked potential variations using correlated scale function designed by multiresolution analysis

Fast tracking of evoked potential variations is of great importance in clinical operation. The paper describes a method whereby an ensemble averaged signal is used as the prototype of the scale function and designs a correlated scale function based on multiresolution analysis. Hence, an effective low pass digital filter having powerful tracking capability is obtained. Results show that the filter designed filters out the noise more effectively than that using general wavelet filtering, and the tracking of the peak of evoked potential is easily obtained.published_or_final_versio

Estimating black hole masses of blazars

Estimating black hole masses of blazars is still a big challenge. Because of the contamination of jets, using the previously suggested size -- continuum luminosity relation can overestimate the broad line region (BLR) size and black hole mass for radio-loud AGNs, including blazars. We propose a new relation between the BLR size and $H_{\beta}$ emission line luminosity and present evidences for using it to get more accurate black hole masses of radio-loud AGNs. For extremely radio-loud AGNs such as blazars with weak/absent emission lines, we suggest to use the fundamental plane relation of their elliptical host galaxies to estimate the central velocity dispersions and black hole masses, if their velocity dispersions are not known but the host galaxies can be mapped. The black hole masses of some well-known blazars, such as OJ 287, AO 0235+164 and 3C 66B, are obtained using these two methods and the M - $\sigma$ relation. The implications of their black hole masses on other related studies are also discussed.Comment: 7 pages, invited talk presented in the workshop on Multiwavelength Variability of Blazars (Guangzhou, China, Sept. 22-24, 2010). To be published in the Journal of Astrophysics and Astronom

Adaptive neural network filter for visual evoked potential estimation

The authors describe a new approach to enhance the signal-to-noise-ratio (SNR) of visual evoked potential (VEP) based on an adaptive neural network filter. Neural networks are usually used in an nonadaptive way. The weights in the neural network are adjusted during training but remain constant in actual use. Here, the authors use an adaptive neural network filter with adaptation capabilities similar to those of the traditional linear adaptive filter and suitable training scheme is also examined. In contrast with linear adaptive filters, adaptive neural network filters possess nonlinear characteristics which can better match the nonlinear behaviour of evoked potential signals. Simulations employing VEP signals obtained experimentally confirm the superior performance of the adaptive neural network filter against traditional linear adaptive filter.published_or_final_versio

Estimation of Evoked Potentials Using Wavelet Transform Based Time-Frequency Adaptive Filtering

A time-frequency domain adaptive filtering method is presented to estimate evoked potentials. The wavelet transform is used to represent the original responses in the time-frequency domain with a discrete set of wavelet coefficients. Each coefficient, which is related to the time extent and the frequency extent in the time-frequency plane, is processed by an adaptive signal enhancer (ASE) to enhance the signal components. The processed coefficients are then used to reconstruct the evoked potential signals with the inverse wavelet transform. Visual evoked potentials (VEPs) from human subjects are estimated, and good results are obtained by this method,published_or_final_versio

Fast measurement of SEP for monitoring spinal cord during scoliosis

Recently there has been considerable interest in the use of somatosensory evoked potential (SEP) for monitoring the functional integrity of the spinal cord during surgery such as scoliosis. This paper describes a monitoring system and signal processing algorithms, which consist of an artificial neural network filter and a wavelet signal enhancer developed to enhance the signal-to-noise ratio (SNR) of surface recorded SEP. Our system allows fast detection of change in SEP's peak latency, amplitude and signal waveform, which are the main parameters of interest during intra-operative procedures.published_or_final_versionThe 20th IEEE Engineering in Medicine and Biology Society Conference Proceedings, Hong Kong, China, 29 October - 1 November 1998, v. 4, p. 2239-224

Hidden charm and bottom molecular states

We investigate heavy quark symmetries for heavy light meson-antimeson systems in a contact-range effective field theory. In the SU(3) light flavor limit, the leading order Lagrangian respecting heavy quark spin symmetry contains four independent counter-terms. Neglecting 1/mQ corrections, three of these low energy constants can be determ1ined by theorizing a molecular description of the X(3872) and Zb(10610) states. Thus, we can predict new hadronic molecules, in particular the isovector charmonium partners of the Zb(10610) and the Zb(10650) states. We also discuss hadron molecules composed of a heavy meson and a doubly-heavy baryon, which would be related to the heavy meson-antimeson molecules thanks to the heavy antiquark-diquark symmetry. Finally, we also study the X(3872)→D0D¯0π0 decay, which is not only sensitive to the short distance part of the X(3872) molecular wave function, as the J/ψππ and J/ψ3π X(3872) decay modes are, but it is also affected by the long-distance structure of the resonance. Furthermore, this decay might provide some information on the interaction between the DD¯ charm mesons

Differential Regulation of the Period Genes in Striatal Regions following Cocaine Exposure

Several studies have suggested that disruptions in circadian rhythms contribute to the pathophysiology of multiple psychiatric diseases, including drug addiction. In fact, a number of the genes involved in the regulation of circadian rhythms are also involved in modulating the reward value for drugs of abuse, like cocaine. Thus, we wanted to determine the effects of chronic cocaine on the expression of several circadian genes in the Nucleus Accumbens (NAc) and Caudate Putamen (CP), regions of the brain known to be involved in the behavioral responses to drugs of abuse. Moreover, we wanted to explore the mechanism by which these genes are regulated following cocaine exposure. Here we find that after repeated cocaine exposure, expression of the Period (Per) genes and Neuronal PAS Domain Protein 2 (Npas2) are elevated, in a somewhat regionally selective fashion. Moreover, NPAS2 (but not CLOCK (Circadian Locomotor Output Cycles Kaput)) protein binding at Per gene promoters was enhanced following cocaine treatment. Mice lacking a functional Npas2 gene failed to exhibit any induction of Per gene expression after cocaine, suggesting that NPAS2 is necessary for this cocaine-induced regulation. Examination of Per gene and Npas2 expression over twenty-four hours identified changes in diurnal rhythmicity of these genes following chronic cocaine, which were regionally specific. Taken together, these studies point to selective disruptions in Per gene rhythmicity in striatial regions following chronic cocaine treatment, which are mediated primarily by NPAS2. © 2013 Falcon et al

Three-dimensional jamming and flows of soft glassy materials

Various disordered dense systems such as foams, gels, emulsions and colloidal suspensions, exhibit a jamming transition from a liquid state (they flow) to a solid state below a yield stress. Their structure, thoroughly studied with powerful means of 3D characterization, exhibits some analogy with that of glasses which led to call them soft glassy materials. However, despite its importance for geophysical and industrial applications, their rheological behavior, and its microscopic origin, is still poorly known, in particular because of its nonlinear nature. Here we show from two original experiments that a simple 3D continuum description of the behaviour of soft glassy materials can be built. We first show that when a flow is imposed in some direction there is no yield resistance to a secondary flow: these systems are always unjammed simultaneously in all directions of space. The 3D jamming criterion appears to be the plasticity criterion encountered in most solids. We also find that they behave as simple liquids in the direction orthogonal to that of the main flow; their viscosity is inversely proportional to the main flow shear rate, as a signature of shear-induced structural relaxation, in close similarity with the structural relaxations driven by temperature and density in other glassy systems.Comment: http://www.nature.com/nmat/journal/v9/n2/abs/nmat2615.htm