Design consideration of a multi-function otoacoustic emission measurement system

A new approach for recording otoacoustic emissions (OAEs) is described in the paper. The system is based on a personal computer equipped with INTEL Pentium CPU. A single chip microcomputer INTEL 8096 is developed to be a stimulus generator. Some critical problems and circuit parameters in the design of this system are presented in the paper. The main advantages of the system are (1) it can record three kinds of OAEs which have many clinical applications; (2) it can save raw data for further analysis, as most researchers need; (3) plenty of analysis functions can be developed in this system. With the use of the newly developed system, SOAEs, TEOAEs, and DPOAEs have been successfully measured.published_or_final_versio

Multi-resolution decomposition applied to crackle detection

Crackles, heard over the lungs in a variety of diseases, are one of the most important physical signs in clinical medicine. They have an explosive pattern in the time domain, with a rapid onset and short duration. The timing, repeatability and shape of crackles are important parameters for diagnosis. Therefore, automatic detection of crackles and their classification as fine and coarse crackles have important clinical value. Since the multi-resolution decomposition technique can give high resolution in both time and frequency, it can be exploited to detect crackles and to classify them according to the information in each scale. In this paper, we present a new method for crackle detection based on the continuous wavelet transform. The theory, methods and experimental results are given in detail in this paper.published_or_final_versio

Crackle detection and classification based on matched waveletanalysis

Crackles have an explosive pattern in the time domain, with a rapid onset and a short duration. The timing, repeatability and shape of crackles are important parameters for diagnosis. Therefore, automatic detection of crackles and their classification have important clinical value. Since crackles have a general characteristic shape, it is obvious that wavelet analysis can be exploited to detect crackles and to classify them. In this paper, we present a new method for crackle detection which is based on a `matched' wavelet transform. We first model crackles as a mathematical function. Then we design a matched wavelet based on this model. Applying a soft threshold to the results of the continuous wavelet transform to suppress noise further, the optimal scale can be obtained. Crackles can be detected based on the envelope of the signal at an optimal scale, and can be classified based on the energy distribution with scale. Theory, methods and experimental results are given in detail in this paper.published_or_final_versio

Effective preconditioning methods for in vitro propagation of Uapaca kirkiana Müell Arg. tree species

The objective of the study was to determine efficient preconditioning methods for in vitro multiplication of Uapaca kirkiana plant materials from mature stock plants. The efficacy of sodium hypochlorite(NaOCl), calcium hypochlorite {Ca(OCl2)2} or mercuric chloride (HgCl2) as surface sterilant was evaluated in decontaminating explants excised from grafted and field-collected U. kirkiana trees.Different Murashige and Skoog (MS) medium supplements were evaluated for shoot multiplication and root regeneration. Results indicated that preconditioning grafted U. kirkiana trees before excisingexplants and decontaminating explants in 0.1% w/v HgCl2 were effective methods in establishing aseptic cultures (80%). Lateral shoots (new shoots) responded positively to shoot multiplication on ¾strength MS medium supplemented with a combination of 0.1 mg/L benzylaminopurine, 0.04 mg/L naphthaleneacetic acid and 0.3 mg/L casein hydrolysate. High concentrations of thidiazuron (>0.1 mg/L)suppressed bud break. Rooting (36%) was achieved with ½ MS medium supplemented with 2.5 mg/L indole-3-butyric acid. Plantlets were successfully hardened off. In vitro multiplication of mature U.kirkiana plant materials was achieved using lateral shoots excised from grafted U. kirkiana trees after preconditioning with fungicides

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

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

Improved Adaptive Group Testing Algorithms with Applications to Multiple Access Channels and Dead Sensor Diagnosis

We study group-testing algorithms for resolving broadcast conflicts on a multiple access channel (MAC) and for identifying the dead sensors in a mobile ad hoc wireless network. In group-testing algorithms, we are asked to identify all the defective items in a set of items when we can test arbitrary subsets of items. In the standard group-testing problem, the result of a test is binary--the tested subset either contains defective items or not. In the more generalized versions we study in this paper, the result of each test is non-binary. For example, it may indicate whether the number of defective items contained in the tested subset is zero, one, or at least two. We give adaptive algorithms that are provably more efficient than previous group testing algorithms. We also show how our algorithms can be applied to solve conflict resolution on a MAC and dead sensor diagnosis. Dead sensor diagnosis poses an interesting challenge compared to MAC resolution, because dead sensors are not locally detectable, nor are they themselves active participants.Comment: Expanded version of a paper appearing in ACM Symposium on Parallelism in Algorithms and Architectures (SPAA), and preliminary version of paper appearing in Journal of Combinatorial Optimizatio

Observation of an unexpected third receptor molecule in the crystal structure of human interferon-γ receptor complex

AbstractBackground: Molecular interactions among cytokines and cytokine receptors form the basis of many cell-signaling pathways relevant to immune function. Interferon-γ (IFN-γ) signals through a multimeric receptor complex consisting of two different but structurally related transmembrane chains: the high-affinity receptor-binding subunit (IFN-γRα) and a species-specific accessory factor (AF-1 or IFN-γRβ). In the signaling complex, the two receptors probably interact with one another through their extracellular domains. Understanding the atomic interactions of signaling complexes enhances the ability to control and alter cell signaling and also provides a greater understanding of basic biochemical processes.Results: The crystal structure of the complex of human IFN-γ with the soluble, glycosylated extracellular part of IFN-γRα has been determined at 2.9 Å resolution using multiwavelength anomalous diffraction methods. In addition to the expected 2:1 complex, the crystal structure reveals the presence of a third receptor molecule not directly associated with the IFN-γ dimer. Two distinct intermolecular contacts, involving the edge strands of the C-terminal domains, are observed between this extra receptor and the 2:1 receptor–ligand complex thereby forming a 3:1 complex.Conclusions: The observed interactions in the 2:1 complex of the high-affinity cell-surface receptor with the IFN-γ cytokine are similar to those seen in a previously reported structure where the receptor chains were not glycosylated. The formation of β-sheet packing interactions between pairs of IFN-γRα receptors in these crystals suggests a possible model for receptor oligomerization of Rα and the structurally homologous Rβ receptors in the fully active IFN-γ signaling complex

The influence of initial xylose concentration, agitation, and aeration on ethanol production by Pichia stipitis from rice straw hemicellulosic hydrolysate

Rice straw hemicellulosic hydrolysate was used as fermentation medium for ethanol production by Pichia stipitis NRRL Y-7124. Shaking bath experiments were initially performed aiming to establish the best initial xylose concentration to be used in this bioconversion process. In the sequence, assays were carried out under different agitation (100 to 200 rpm) and aeration (V flask/V medium ratio varying from 2.5 to 5.0) conditions, and the influence of these variables on the fermentative parameters values (ethanol yield factor, Y P/S; cell yield factor, Y X/S; and ethanol volumetric productivity, Q P) was investigated through a 22 full-factorial design. Initial xylose concentration of about 50 g/l was the most suitable for the development of this process, since the yeast was able to convert substrate in product with high efficiency. The factorial design assays showed a strong influence of both process variables in all the evaluated responses. The agitation and aeration increase caused a deviation in the yeast metabolism from ethanol to biomass production. The best results (Y P/S = 0.37 g/g and Q P = 0.39 g/l.h) were found when the lowest aeration (2.5 V flask/V medium ratio) and highest agitation (200 rpm) levels were employed. Under this condition, a process efficiency of 72.5% was achieved. These results demonstrated that the establishment of adequate conditions of aeration is of great relevance to improve the ethanol production from xylose by Pichia stipitis, using rice straw hemicellulosic hydrolysate as fermentation medium.The financial support from Fapesp (Brazil) is gratefully acknowledged

Random UV-C mutagenesis of Scheffersomyces (formerly Pichia) stipitis NRRL Y-7124 to improve anaerobic growth on lignocellulosic sugars

Scheffersomyces (formerly Pichia) stipitis NRRL Y-7124 was mutagenized using UV-C irradiation to produce yeast strains for anaerobic conversion of lignocellulosic sugars to ethanol. UV-C irradiation potentially produces large numbers of random mutations broadly and uniformly over the whole genome to generate unique strains. Wild-type cultures of S. stipitis NRRL Y-7124 were subjected to UV-C (234 nm) irradiation targeted at approximately 40% cell survival. When surviving cells were selected in sufficient numbers via automated plating strategies and cultured anaerobically on xylose medium for 5 months at 28°C, five novel mutagenized S. stipitis strains were obtained. Variable number tandem repeat analysis revealed that mutations had occurred in the genome, which may have produced genes that allowed the anaerobic utilization of xylose. The mutagenized strains were capable of growing anaerobically on xylose/glucose substrate with higher ethanol production during 250- to 500-h growth than a Saccharomyces cerevisiae yeast strain that is the standard for industrial fuel ethanol production. The S. stipitis strains resulting from this intense multigene mutagenesis strategy have potential application in industrial fuel ethanol production from lignocellulosic hydrolysates