A new algorithm for time-frequency spread coders using multirate filters

Filter banks have been shown to be efficient in several emerging signal communication applications. A new class of time-frequency spread coders for transmultiplexer systems using multirate filter banks is presented. As compared with conventional filter banks designed with stopband attenuation and passband flatness criteria, the user coders with the new algorithms are designed with time and frequency spread criteria. In new the algorithms, the filters are achieved through a cascade of lattice structures and delay chains. Along with the time-frequency property and the reconstruction property, the intercode/intracode correlation property are included in the design algorithms to be optimized. The designed coders are used in the application of digital watermarking of images and demonstrate good performance in JPEG encoding at different qualities.published_or_final_versio

A new synthesis procedure for linear-phase paraunitary digital filter banks

In this paper, a new design algorithm is presented for a family of linear phase paraunitary filter banks with generalized filter length and symmetric polarity. A number of new constraints on the distributions of filter length and symmetry polarity among the channels are derived. In the algorithm, the lengths of the filters are gradually reduced through a cascade of lattice structures. The derivations for filter banks with even and odd number of channels are formulated in a unified form.published_or_final_versio

Structure and Transport in Coatings from Multiscale Computed Tomography of Coatings-New Perspectives for Eelectrochemical Impedance Spectroscopy Modeling?

Computed Tomography (CT) is an approach that has been extensively applied in many areas of science from understanding structures in living organisms to materials science. In materials science, the study of structures within coatings presents challenges on at least two different levels. First, the structure of the coatings needs to be understood from the atomic scale, where dissolution reactions begin, up to length scales which cover the aggregation of inhibitors and other additives, which take place at ∼10−5 m, i.e. 4 to 5 orders of magnitude. CT is a favourable imaging technique since it allows multiscale information to be obtained non-destructively down to tens of nanometres. In this study X-ray absorption contrast imaging has been used to examine structures created using strontium chromate (SrCrO4) particles embedded in an epoxy film. It has been found that SrCrO4 particles can form clusters that extend a few hundred microns in the plane of the film, span the thickness of the film and have fractal characteristics. There are also volumes of low density epoxy of similar sizes and characteristics to the SrCrO4 clusters. The SrCrO4 clusters have a strong influence on the leaching behaviour since the release changes with time. Initially, leaching is controlled by direct dissolution but, as the clusters dissolve, the release is dominated by the fractal dimension of the cluster. The dissolved clusters leave behind voids filled with electrolyte that provide alternative transport pathways for corrosive ions through the polymer. In this paper, the nature of these clusters will be reviewed and the implication for transport properties and electrochemical assessment will be explored

Investigation of the cerebral hemodynamic response function in single blood vessels by functional photoacoustic microscopy

The specificity of the hemodynamic response function (HRF) is determined spatially by the vascular architecture and temporally by the evolution of hemodynamic changes. Here, we used functional photoacoustic microscopy (fPAM) to investigate single cerebral blood vessels of rats after left forepaw stimulation. In this system, we analyzed the spatiotemporal evolution of the HRFs of the total hemoglobin concentration (HbT), cerebral blood volume (CBV), and hemoglobin oxygen saturation (SO2). Changes in specific cerebral vessels corresponding to various electrical stimulation intensities and durations were bilaterally imaged with 36 × 65-μm2 spatial resolution. Stimulation intensities of 1, 2, 6, and 10 mA were applied for periods of 5 or 15 s. Our results show that the relative functional changes in HbT, CBV, and SO2 are highly dependent not only on the intensity of the stimulation, but also on its duration. Additionally, the duration of the stimulation has a strong influence on the spatiotemporal characteristics of the HRF as shorter stimuli elicit responses only in the local vasculature (smaller arterioles), whereas longer stimuli lead to greater vascular supply and drainage. This study suggests that the current fPAM system is reliable for studying relative cerebral hemodynamic changes, as well as for offering new insights into the dynamics of functional cerebral hemodynamic changes in small animals. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE)

The Effect of a Hip Strengthening Program on Mechanics during Running and Single Leg Squatting

STUDY DESIGN: Block randomized controlled trial. OBJECTIVES: To investigate whether a strengthening and movement education program, targeting the hip abductors and hip external rotators, alters hip mechanics during running and during a single-leg squat. BACKGROUND: Abnormal movement patterns during running and single-leg squatting have been associated with a number of running-related injuries in females. Therapeutic interventions for these aberrant movement patterns typically include hip strengthening. While these strengthening programs have been shown to improve symptoms, it is unknown if the underlying mechanics during functional movements is altered. METHODS: Twenty healthy females with excessive hip adduction during running, as determined by instrumented gait analysis, were recruited. The runners were matched by age and running distance, and randomized to either a training group or a control group. The training group completed a hip strengthening and movement education program 3 times per week for 6 weeks in addition to single-leg squat training with neuromuscular reeducation consisting of mirror and verbal feedback on proper mechanics. The control group did not receive an intervention but maintained the current running distance. Using a handheld dynamometer and standard motion capture procedures, hip strength and running and single-leg squat mechanics were compared before and after the strengthening and movement education program. RESULTS: While hip abductor and external rotation strength increased significantly (P<.005) in the training group, there were no significant changes in hip or knee mechanics during running. However, during the single-leg squat, hip adduction, hip internal rotation, and contralateral pelvic drop all decreased significantly (P = .006, P = .006, and P = .02, respectively). The control group exhibited no changes in hip strength, nor in the single-leg squat or running mechanics at the conclusion of the 6-week study. CONCLUSION: A training program that included hip strengthening and movement training specific to single-leg squatting did not alter running mechanics but did improve single-leg squat mechanics. These results suggest that hip strengthening and movement training, when not specific to running, do not alter abnormal running mechanics. LEVEL OF EVIDENCE: Therapy, level 2b. NOTE: This is not the final published version. The final version was published in the Journal of Orthopaedic and Sports Physical Therapy. 2011 Sep; 41(9): 625-32. doi: 10.2519/jospt.2011.347

Effect of influenza on cardiorespiratory and all-cause mortality in Hong Kong, Singapore and Guangzhou.

1. Using a common modelling approach, mortality attributable to influenza was higher in the two subtropical cities Guangzhou and Hong Kong than in the tropical city Singapore. 2. The virus activity appeared more synchronised in subtropical cities, whereas seasonality of influenza tended to be less marked in the tropical city. 3. High temperature was associated with increased mortality after influenza infection in Hong Kong, whereas relative humidity was an effect modifier for influenza in Guangzhou. No effect modification was found for Singapore. 4. Seasonal and environmental factors probably play a more important role than socioeconomic factors in regulating seasonality and disease burden of influenza. Further studies are needed in identifying the mechanism behind the regulatory role of environmental factors.published_or_final_versio

A new multi-anticipative car-following model with consideration of the desired following distance

We propose in this paper an extension of the multi-anticipative optimal velocity car-following model to consider explicitly the desired following distance. The model on the following vehicle’s acceleration is formulated as a linear function of the optimal velocity and the desired distance, with reaction-time delay in elements. The linear stability condition of the model is derived. The results demonstrate that the stability of traffic flow is improved by introducing the desired following distance, increasing the time gap in the desired following distance or decreasing the reaction-time delay. The simulation results show that by taking into account the desired following distance as well as the optimal velocity, the multi-anticipative model allows longer reaction-time delay in achieving stable traffic flows