Limits on discrete modulated signals

We develop theorems of a general nature that apply to the analysis of AM-FM signals of the form a(m)exp [jφ(m)] or a(m) cos [φ(m)] and to their behavior both in linear systems and in simple nonlinear systems comprised of products of linear elements. Such product-systems include interesting nonlinear demodulation operators, such as the Teager-Kaiser (1990) operator. Expressions for the approximate system responses to AM-FM signals are derived by making an analogy to the eigenfunction interpretation of sinusoids in linear systems; for the case of sinusoidal signals, the approximations are exact. These expressions are collectively called quasieigenfunction approximations (QEAs). For nonsinusoidal AM-FM signals, the approximations have errors that are tightly bounded by functionals that express the smoothness of the AM and FM information signals and the durations of the involved system impulse responses. The bounds are independent of the bandwidths of the AM and FM functions. Two general applications are considered. First, the approximations are found to be useful for analyzing discrete-time nonlinear energy operators, including the Teager-Kaiser operator. Next, the approximation theorems lead to the selection of an optimal class of bandpass filters for use in a discrete multiband AM-FM demodulation system. The filter class selected is optimal in the sense of achieving the lower bound of a novel discrete uncertainty principle     

Multicomponent Multidimensional Signals

In this brief paper, we extend the notion of multicomponent signal into multiple dimensions. A definition for multidimensional instantaneous bandwidth is presented and used to develop criteria for determining the multicomponent nature of a signal. We demonstrate application of the criteria by testing the validity of a multicomponent interpretation for a complicated nonstationary texture image.     

Manufacturing system engineering ontology for semantic interoperability across extended project teams

Communication, knowledge sharing and awareness of available expertise are complex issues for any multidiscipline team. Complexity increases substantially in extended enterprise environments. The concepts of an MSE Moderator have previously been considered in environments with shared information models and vocabularies. These concepts are now translated to the realm of extended enterprises, where inevitably, individual partners will have their own terminology and information sources. An MSE Ontology is proposed to enable the operation of an extended enterprise MSE Moderator to provide common understanding of manufacturing-related terms, and therefore to enhance the semantic interoperability and reuse of knowledge resources within globally extended manufacturing teams.     

Wide temperature (-20°C-95°C) operation of an uncooled2.5-Gb/s 1300-nm DFB laser

This letter describes a 2.5-Gb/s 1300-nm distributed feedback laser that can operate in a wide temperature range of -20°C to 95°C. We present RF and DC characteristics of the device and the statistical distribution of threshold current and slope efficiency at high temperature. Finally, we demonstrate the device performance in a 2.5-Gb/s small-form-factor module up to 85°C     

Sequence and analysis of the genome of a baculovirus pathogenic for Lymantria dispar

Cyclic nucleotide-gated channels are composed of a core transmembrane domain, structurally homologous to the voltage-gated K+ channels, and a cytoplasmic ligand-binding domain. These two modules are joined by approximately 90 conserved amino acids, the C-linker, whose precise role in the mechanism of channel activation by cyclic nucleotides is poorly understood. We examined cyclic nucleotide-gated channels from bovine photoreceptors and Caenorhabditis elegans sensory neurons that show marked differences in cyclic nucleotide efficacy and sensitivity. By constructing chimeras from these two channels, we identified a region of 30 amino acids in the C-linker (the L2 region) as an important determinant of activation properties. An increase in both the efficacy of gating and apparent affinity for cGMP and cAMP can be conferred onto the photoreceptor channel by the replacement of its L2 region with that of the C. elegans channel. Three residues within this region largely account for this effect. Despite the profound effect of the C-linker region on ligand gating, the identity of the C-linker does not affect the spontaneous, ligand-independent open probability. Based on a cyclic allosteric model of activation, we propose that the C-linker couples the opening reaction in the transmembrane core region to the enhancement of the affinity of the open channel for agonist, which underlies ligand gating.     

Genomic-sequence comparison of two unrelated isolates of the human gastric pathogen Helicobacter pylori

Helicobacter pylori, one of the most common bacterial pathogens of humans, colonizes the gastric mucosa, where it appears to persist throughout the host's life unless the patient is treated. Colonization induces chronic gastric inflammation which can progress to a variety of diseases, ranging in severity from superficial gastritis and peptic ulcer to gastric cancer and mucosal-associated lymphoma. Strain-specific genetic diversity has been proposed to be involved in the organism's ability to cause different diseases or even be beneficial to the infected host and to participate in the lifelong chronicity of infection. Here we compare the complete genomic sequences of two unrelated H. pylori isolates. This is, to our knowledge, the first such genomic comparison. H. pylori was believed to exhibit a large degree of genomic and allelic diversity, but we find that the overall genomic organization, gene order and predicted proteomes (sets of proteins encoded by the genomes) of the two strains are quite similar. Between 6 to 7% of the genes are specific to each strain, with almost half of these genes being clustered in a single hypervariable region.     

Second order components of moving plaids activate extrastriate cortex: a positron emission tomography study

A moving plaid is a composite pattern produced by superimposing two sinusoidal gratings which differ in orientation and motion direction. The perceived drift direction of a plaid appears to be determined partly by a binocular mechanism, which follows intersection of constraint rules (Burke and Wenderoth, 1993b), and partly by a monocular mechanism, which tracks the dark and bright intersects of the plaid, the contrast envelopes. The first neurones that respond to plaids as patterns rather than component gratings are found in area V5, also known as MT, which is exclusively binocular. Therefore, the psychophysical evidence suggesting that the contrast envelope tracking mechanism is monocular is surprising but has been obtained consistently. We aimed to localize the contrast envelope tracking mechanism by undertaking a positron emission tomography (PET) activation experiment in which the subjects were presented with alternating plaid components during the control scan and with the moving plaid resulting from the superposition of these components as the activation scan. The results showed differential activation in area V3. Recent results from macaque single cell recordings have also demonstrated increased sensitivity to moving plaid stimuli compared to the plaid component gratings in V3 neurones.     

Clinical decision-making: How prepared are we?

The importance of decision-making skills for clinical psychologists has been established. This study investigates the amount of academic instruction received by graduate students in this subject area. Courses from American Psychological Association accredited clinical psychology programs were examined, along with surveys completed by academic training directors (DCTs). Findings indicate limited formal academic instruction within the area of clinical decision-making, despite DCT importance ratings. Coverage of decision-making topics rarely occurs in stand-alone courses. Fewer than 50% of programs cover decision theory or decision improvement strategies. Suggestions are offered to address the discrepancy between essential clinical judgment capacities and amount of provided instruction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mask estimation for missing data speech recognition based on statistics of binaural interaction

This paper describes a perceptually motivated computational auditory scene analysis (CASA) system that combines sound separation according to spatial location with the "missing data" approach for robust speech recognition in noise. Missing data time-frequency masks are created using probability distributions based on estimates of interaural time and level differences (ITD and ILD) for mixed utterances in reverberated conditions; these masks indicate which regions of the spectrum constitute reliable evidence of the target speech signal. A number of experiments compare the relative efficacy of the binaural cues when used individually and in combination. We also investigate the ability of the system to generalize to acoustic conditions not encountered during training. Performance on a continuous digit recognition task using this method is found to be good, even in a particularly challenging environment with three concurrent male talkers.     

Contaminants and levels of occurrence in washed and shredded poly(ethylene terephthalate) from curbside collection. Part 1: Extraction conditions

The aim was to determine which contaminants were present in washed and dried shredded poly(ethylene terephthalate) (PET, flake) obtained from curbside collection and whether the concentrations were above the US FDA threshold of 215 ppb. Thirty-two semi-volatile contaminants were extracted from the treated flake by Soxhlet extraction using dichloromethane as a PET swelling solvent and gas chromatography-mass spectrometry (GC-MS) was used for identification and quantification. Soxhlet extraction of flake ground to 0-300 pm was effectively completed in 24 h, whereas sonication reduced the extraction time to 3 h. In contrast, Soxhlet extractions of flake ground to a larger particle size range (300-425 pm) were completed in 4 h, possibly due to less aggregation in the extraction thimble. The levels of 26 contaminants were below 215 ppb, but six were not. Dodecanoic acid was present at about 1200 ppb, 2-butoxyethanol was approximately 1000 ppb, limonene, benzophenone and methyl salicylate were above 800 ppb, and 2-methyl-naphthalene near 215 ppb.