bluuebunny/crossref_metadata_2025 huggingface dataset:
Soy‐Derived Immunoglobulin Production Stimulating Factor Enhances IgM Production of Mouse Spleen Lymphocytes
Authors: Maeda N. , Yoshimi K. , Tachibana H. , Yamada K.
Published: September 2006

ABSTRACT:  We have reported previously that some proteins such as lactoferrin and lysozyme control the immune system via immunoglobulin (Ig) production. In the course of the study about the function of dietary proteins and peptides, Ig production‐stimulating activity of an unknown protein contained in soybean trypsin inhibitor (STI) preparation was found. Thus, we examined the activity of the unknown activator and the mechanism of the activity. The factor significantly elevated IgM production by mouse spleen lymphocytes in a dose‐dependent manner. In addition, the unknown activator up‐regulated the expression of interleukin (IL)‐6 and IL‐10 mRNA. And IgM production enhancing activity of STI was significantly suppressed by neutralization of IL‐6. Then, to clarify whether STI itself is the active compound or not, STI was fractionized by gel filtration chromatography. We found that the activity the content of STI did not correlate with and the active fractions contained some proteins whose molecular weight is more than 20 kDa. These suggest that an unknown activator exists in STI preparation.
Fractionating Soybean Storage Proteins Using Ca2+ and NaHSO3
Authors: Deak N.A. , Murphy P.A. , Johnson L.A.
Published: September 2006

ABSTRACT:  Individual soybean storage proteins have been identified as having nutraceutical properties, especially β‐conglycinin. Several methods to fractionate soy proteins on industrial scales have been published, but there are no commercial products of fractionated soy proteins. The present study addresses this problem by using calcium salts to achieve glycinin‐rich and β‐conglycinin‐rich fractions in high yields and purities. A well‐known 3‐step fractionation procedure that uses SO2, NaCl, and pH adjustments was evaluated with CaCl2 as a substitute for NaCl. Calcium was effective in precipitating residual glycinin, after precipitating a glycinin‐rich fraction, into an intermediate fraction at 5 to 10 mM CaCl2 and pH 6.4, eliminating the contaminant glycinin from the β‐conglycinin‐rich fraction. Purities of 100%β‐conglycinin with unique subunit compositions were obtained after prior precipitation of the glycinin‐rich and intermediate fractions. The use of 5 mM SO2 in combination with 5 mM CaCl2 in a 2‐step fractionation procedure produced the highest purities in the glycinin‐rich (85.2%) and β‐conglycinin‐rich (80.9%) fractions. The glycinin in the glycinin‐rich fraction had a unique acidic (62.6%) to basic (37.4%) subunit distribution. The β‐conglycinin‐rich fraction was approximately evenly distributed among the β‐conglycinin subunits (30.9%, 35.8%, and 33.3%, for α', α, and β subunits, respectively). Solids yields and protein yields, as well as purities and subunit compositions, were highly affected by pH and SO2 and CaCl2 concentrations.
Impact of Thermal Treatment and Storage on Color of Yellow‐Orange Cactus Pear (Opuntia ficus‐indica[L.] Mill. cv. ‘Gialla’) Juices
Authors: Moßhammer M.R. , Maier C. , Stintzing F.C. , Carle R.
Published: September 2006

ABSTRACT:  The impact of heating at 75, 85, and 95 °C during 60 min on overall color and betalain retention of yellow‐orange cactus pear (Opuntia ficus‐indica[L.] Mill. cv. ‘Gialla’) juice after a 24‐h color regeneration period was investigated. The addition of 0.1% isoascorbic acid prior to heating minimized color alteration as well as betalain degradation to a significant level. A correlation between the total betaxanthin retention and the indicaxanthin/isoindicaxanthin ratio was detected in heated juice samples, thus proving the indicaxanthin/isoindicaxanthin ratio as a valuable indicator of thermally treated cactus pear juices. Notably, the same ratio was instrumental for retrospectively calculating the initial betaxanthin content. Additionally, storage experiments over a period of 6 mo were conducted. Samples kept in the dark exhibited notably better color and pigment retentions as compared to illuminated samples. A significantly stabilizing effect was also observed in samples with isoascorbic acid fortification. While indicaxanthin and betanin were predominantly degraded through hydrolytic cleavage upon both heat exposure and storage, isomerization was only marginal for betanin. In contrast, 2‐decarboxy‐betanin formation was exclusively found for nonfortified heated samples while decarboxylated indicaxanthin could not be detected.
Effect of Gamma Radiation on Furan Formation in Ready‐to‐Eat Products and their Ingredients
Authors: Fan Xuetong , Sommers Christopher H.
Published: September 2006

ABSTRACT:  Besides meat as the major component, ready‐to‐eat (RTE) meat and poultry products often contain ingredients such as Na‐ascorbate, Na‐erythorbate, glucose, honey, corn syrup, and Na‐nitrite. Furan is a potential carcinogen and information is needed on its formation in irradiated RTE products. In the present study, we investigated the generation of irradiation‐induced furan in aqueous solutions of those ingredients, and in 9 RTE food products (8 meat and poultry‐based and 1 vegetable burger). Irradiation at doses up to 4.5 kGy induced formation of furan in aqueous solutions of Na‐ascorbate, Na‐erythorbate, glucose, honey, and corn syrup. Addition of Na‐nitrite into these solutions prior to irradiation completely eliminated, or significantly reduced, furan formation. Most of the nonirradiated RTE products contained less than 1 ng/g of furan, except for beef and turkey frankfurters which contained 6 to 8 ng/g furan. Exposure of RTE food products to 4.5 kGy radiation in the nonfrozen state (5 °C) or to 10 kGy radiation in the frozen state (−18 °C) did not significantly increase furan levels in most of the samples. Furthermore, the irradiation treatments reduced furan levels in samples (that is, frankfurters) that contained more than 3 ng/g of furan. Our results suggested that irradiation induces furan formation in solutions of many RTE food ingredients, but not in RTE meat and poultry products themselves.
Extraction of Lignan Compounds from Roasted Sesame Oil and their Effects on the Autoxidation of Methyl Linoleate
Authors: Lee Jinyoung , Choe Eunok
Published: September 2006

ABSTRACT:  Lignan compounds were extracted from roasted sesame oil and their effects on the autoxidation of methyl linoleate (ML) were studied. Lignan compounds extracted from roasted sesame oil, sesamol, sesamin, and sesamolin, were added to ML, which was then oxidized at 60 oC for 18 h in the dark. Alpha‐tocopherol was separately added to ML for a reference antioxidant. Degree of ML oxidation was monitored by conjugated dienoic acid (CDA) contents and p‐anisidine value (PAV) by AOCS methods, and ML retention by gas chromatography. CDA contents and PAV of samples increased with the oxidation time at 60 oC in the dark, and ML decreased. Sesamol‐, sesamin‐, or sesamolin‐added samples showed lower CDA contents, PAV, and ML loss than the samples without lignans during oxidation in the dark, which indicated that lignan compounds lowered the ML autoxidation. The antioxidant activity of sesamol was significantly higher (P < 0.05) than that of sesamin, sesamolin, or α‐tocopherol. Lignan compounds added to ML were degraded during the autoxidation of ML, and the degradation rate was higher in sesamol‐ than in sesamin‐, or sesamolin‐added ML, but was lower than in tocopherol‐added samples. As the lignan compounds concentration in ML increased, the degradation rate of lignans decreased, and the inhibition of the ML autoxidation by lignan compounds increased. The results strongly suggested that the autoxidative stability of ML could be improved by the addition of sesamol, sesamin, or sesamolin extracted from the roasted sesame oil.
Frequency and pattern dependence of adrenergic and purinergic vasoconstriction in rat skeletal muscle arteries
Authors: Kluess Heidi A. , Buckwalter John B. , Hamann Jason J. , DeLorey Darren S. , Clifford Philip S.
Published: September 2006

Sympathetic nerves fire in bursts followed by brief periods of quiescence. Periods of quiescence may be a valuable part of coding for different neurotransmitters. We compared adrenergic‐ and non‐adrenergic‐mediated vasoconstriction with repeating burst patternsversusconstant frequency stimulation. Seventeen rats were killed, and the femoral arteries dissected out and mounted in organ tissue baths at 37°C and pH 7.4. Field stimulation was applied to artery rings from five rats at constant frequencies of 2–6 Hz for 144 impulses. In 12 rats, artery rings were stimulated with two burst pattern protocols consisting of repeating pairs, triplets, quadruplets or sextuplets performed using either 8 or 30 Hz as the instantaneous frequency for a total of 144 impulses. All protocols were repeated with the P2 purinergic antagonist pyridoxal‐phosphate‐6‐azophenyl‐2′4′‐disulphonic acid (PPADs; 0.42m) or the α1‐antagonist prazosin (1.59 μm). Tension was decreased by the addition of the P2 antagonist PPADs (P< 0.05). Prazosin abolished tension at all constant frequencies (P< 0.05). P2 and α1‐antagonism decreased tension with 8 and 30 Hz burst pattern field stimulation. However, the magnitude of decrease in tension with prazosin was less with burst patterns compared to the same average constant frequencies (P< 0.05). It appears that P2X receptors and α1‐receptors in the femoral artery are sensitive to frequency and patterns of electrical stimulation.
β‐Adrenergic receptor desensitization in man: insight into post‐exercise attenuation of cardiac function
Authors: Hart Emma , Dawson Ellen , Rasmussen Peter , George Keith , Secher Niels H. , Whyte Greg , Shave Rob
Published: September 2006

Desensitization of the β‐adrenoreceptors (β‐AR) may contribute to a post‐exercise reduction in left ventricular (LV) function. However, attenuation of the chronotropic and inotropic responses to a β‐AR agonist may depend upon alterations in parasympathetic tone. Furthermore, changes in cardiac outputand LV diastolic function in response to a β‐AR agonist, pre‐ to post‐prolonged exercise, remain unclear. Seven trained males (mean ±s.d., age 27 ± 6 years) performed 4 h of ergometer rowing. Peak heart rate (HR) and LV systolic and diastolic functional responses to incremental isoproterenol (isoprenaline) infusion (2, 4 and 6 μg kg min−1) were assessed after vagal blockade (glycopyrrolate, 1.2 mg). LV systolic function was assessed by the pressure/volume ratio (systolic blood pressure/end systolic volume) and, whilst diastolic function was evaluated as peak early and late transmitral filling velocities. Following exercise, the pressure/volume ratio decreased by 25% (P< 0.05), whereaswas unchanged (P> 0.05). The early/late filling ratio was reduced by 36% after exercise, due to an elevation in late LV filling (P< 0.01). The increase in HR response to isoproterenol infusion was blunted post‐exercise at both 4 and 6 μg kg min−1(127 ± 7 and 132 ± 6 beats min−1) compared with pre‐exercise (138 ± 8 and 141 ± 12 beats min−1,P< 0.05). Additionally, the pressure/volume ratio andwere blunted post‐exercise in response to isoproterenol (P< 0.05). In contrast, diastolic function was similar before and after exercise during isoproterenol infusion (P> 0.05). Desensitization of the β‐AR contributes to an attenuated left ventricular systolic but not diastolic function following prolonged exercise.
Fast forward to new genes in mammalian reproduction
Authors: Furnes Bjarte , Schimenti John
Published: September 2006

The study of reproductive genetics in mammals has lagged behind that of simpler and more tractable model organisms, such as D. melanogaster, C. elegans and various yeast models. Although much valuable information has been generated using these organisms, they do not model the genetic and biological complexity of mammalian reproduction. Thus, the majority of genes required for gametogenesis in mammals remain unidentified. To expand on the existing knowledge of mammalian reproductive genetics, we have carried out forward genetic screens in mice to identify infertility mutants and the underlying mutant genes. Two different approaches were used: mutagenesis of the germline in whole mice, and mutagenesis of embryonic stem cells. This was followed by two‐ or three‐generation breeding schemes to identify pedigrees segregating infertility mutations, which were then phenotypically characterized, genetically mapped, and in some cases, positionally cloned. This whole‐genome approach has generated a wide collection of mutants with defects ranging from problems with germ cell development to abnormal sperm morphology. These models have allowed us to study the genetics, as well as the physiology, of reproduction in mammals. This review focuses on describing some of the genes identified in these screens and the ongoing effort to characterize additional mutants.
Optical properties of amorphous GaAs1−xNx film sputtering with different N2 partial pressures
Authors: Teng X. M. , Fan H. T , Pan S. S. , Ye C. , Li G. H.
Published: September 2006

We study the optical properties of amorphous GaAs1−xNx films grown by radio frequency magnetron sputtering method with different N2 partial pressures. The surface morphology, the optical absorption, the Raman spectra, and optical constants of the films with different N2 partial pressures are reported. The appearance of the Raman peak at 245cm−1 of “GaAslike” and a shoulder at about 750cm−1 related to GaN indicates the formation of GaN clusters in GaAs matrix. The roughness decreases and the optical band gap of amorphous GaAs1−xNx films moves to short wavelength with increasing N2 partial pressure. The refractive index and the extinction coefficient of the films decrease with increasing N2 partial pressure, and it has been found that the amorphous GaAs1−xNx films with nonzero N2 partial pressure are transparent in red and near infrared wavelength regions.
Silicon dioxide etching process for fabrication of micro-optics employing pulse-modulated electron-beam-excited plasma
Authors: Takeda Keigo , Ohta Takayuki , Ito Masafumi , Hori Masaru
Published: September 2006

Silicon dioxide etching process employing a pulse-modulated electron-beam-excited plasma (EBEP) has been developed for a fabrication process of optical micro-electro-mechanical systems (MEMSs). Nonplanar dielectric materials were etched by using self-bias induced by the electron beam generating the plasma. In order to investigate the effect of pulse modulation on electron beam, plasma diagnostics were carried out in the EBEP employing C4F8 gas diluted with Ar gas by using a Langmuir single probe and time resolved optical emission spectroscopy. It was found that the pulse-modulated EBEP has an excellent potential to reduce the plasma-induced thermal damage on a photoresist film on a substrate to get the uniform etching and the anisotropic SiO2 etching in comparison with the conventional EBEP. The pulse-modulated EBEP enabled us to get the high etch rate of SiO2 of 375nm∕min without any additional bias power supply. Furthermore, the microfabrication on the core area of optical fiber was realized. These results indicate that the pulse-modulated EBEP will be a powerful tool for the application to optical MEMS process.
Zinc oxide-based transparent conductive oxide films prepared by pulsed magnetron sputtering from powder targets: Process features and film properties
Authors: Kelly P. J. , Zhou Y.
Published: September 2006

The pulsed magnetron sputtering of transparent conductive oxide (TCO) films from powder targets is a promising technique, which produces films with dense columnar, defect-free structures and optical and electrical properties comparable to other deposition techniques. The targets are formed from loosely packed oxide powder blends, and no additional processes, such as sintering, are required. This preparation method allows target composition and, therefore, film composition (a key parameter in TCO coatings) to be readily varied. The flexibility of this approach was exploited to produce a series of doped zinc oxide coatings, in which both the dopant level (1–5at.%) and the dopant material (Al, Sn, In, Sb, or Ga) were varied systematically. The structures and properties of these coatings were analyzed and measured using a range of techniques, including electron microscopy, spectrophotometry, x-ray diffraction, four-point probe, and Van der Pauw’s method. The TCO coatings were deposited in a rig specially designed for this purpose, and the impact of specific design features on the coating structures and properties are also considered.
Continuous emission of O− ions into a vacuum from a bare surface of yttria-stabilized zirconia at elevated temperatures
Authors: Fujiwara Yukio , Sakai Takaaki , Kaimai Atsushi , Yashiro Keiji , Kawada Tatsuya , Mizusaki Junichiro
Published: September 2006

Emission of oxygen negative ions O− from a bare surface of yttria-stabilized zirconia (YSZ) was studied at 925°C with a quadrupole mass spectrometer capable of detecting negative ions. The use of the mass spectrometer allowed one to identify O− ions, thereby enabling the investigation of emission stability of O− ions. Experimental results demonstrated that O− ions were emitted from the surface of YSZ continuously over 120h. Although emission rate of O− ions decreased gradually with time, the emission rate of O− ions was confirmed to be temporarily restored after intervals. It was found that time constant of decay curve of O− ions was different from that of emission current. An analysis of the decay curves indicated that the difference in the time constants would be due to emission of electrons. Further, the analysis indicated that the number of emitted electrons would decrease with time more rapidly than O− ions, suggesting that it would be attributed to a variation in surface density of chemisorbed oxygen species on emission surface.
Prediction of speech intelligibility in spatial noise and reverberation for normal-hearing and hearing-impaired listeners
Authors: Beutelmann Rainer , Brand Thomas
Published: September 2006

Binaural speech intelligibility of individual listeners under realistic conditions was predicted using a model consisting of a gammatone filter bank, an independent equalization-cancellation (EC) process in each frequency band, a gammatone resynthesis, and the speech intelligibility index (SII). Hearing loss was simulated by adding uncorrelated masking noises (according to the pure-tone audiogram) to the ear channels. Speech intelligibility measurements were carried out with 8 normal-hearing and 15 hearing-impaired listeners, collecting speech reception threshold (SRT) data for three different room acoustic conditions (anechoic, office room, cafeteria hall) and eight directions of a single noise source (speech in front). Artificial EC processing errors derived from binaural masking level difference data using pure tones were incorporated into the model. Except for an adjustment of the SII-to-intelligibility mapping function, no model parameter was fitted to the SRT data of this study. The overall correlation coefficient between predicted and observed SRTs was 0.95. The dependence of the SRT of an individual listener on the noise direction and on room acoustics was predicted with a median correlation coefficient of 0.91. The effect of individual hearing impairment was predicted with a median correlation coefficient of 0.95. However, for mild hearing losses the release from masking was overestimated.
Rytov approximation of tomographic receptions in weakly range-dependent ocean environments
Authors: Piperakis G. S. , Skarsoulis E. K. , Makrakis G. N.
Published: September 2006

An approximation method based on the Born and Rytov approximation is presented for the wave-theoretic prediction of acoustic arrival patterns associated with long-range pulse propagation in weakly range-dependent ocean environments. The environment is considered as a perturbation of a range-independent background state, and normal-mode theory is used, for the representation of the background Green’s function. Using the Born and Rytov approximations, the perturbed Green’s function corresponding to the range-dependent environment is expressed for each frequency within the source bandwidth in terms of the background Green’s function and the medium (sound-speed) perturbation. The actual arrival pattern in the time domain is then computed through the inverse Fourier transform. Using the normal-mode representation, closed-form expressions for the first and second Born and Rytov approximations are derived, generalizing previous range-independent results, and indicating that the effect of range dependence on the acoustic field in the case of adiabatic perturbations is of second order. To cope with the multimodal nature of ocean acoustic propagation, a variation of the standard Rytov method is applied, proposed by Keller, according to which each modal component must be treated independently. A number of numerical examples demonstrate an advantage of the Rytov approximation (over the Born approximation) for time-domain calculations.
A stable boundary element method for modeling transient acoustic radiation
Authors: Chappell D. J. , Harris P. J. , Henwood D. , Chakrabarti R.
Published: September 2006

Transient acoustic radiation from a closed axisymmetric three-dimensional object is modeled using the time domain boundary element method. The widely reported instability problems are overcome by reformulating the integral equation to obtain a Burton and Miller type equation in the time domain. The stability of such an approach is mathematically justified and supported by subsequent numerical results. The hypersingular integrals which arise are evaluated using a method valid for any surface discretization. Numerical results for the radiation of a spherical wave are presented and compared with an exact solution. The accuracy and stability of the results are verified for several geometrically different radiating objects.
Generalized perceptual linear prediction features for animal vocalization analysis
Authors: Clemins Patrick J. , Johnson Michael T.
Published: September 2006

A new feature extraction model, generalized perceptual linear prediction (gPLP), is developed to calculate a set of perceptually relevant features for digital signal analysis of animal vocalizations. The gPLP model is a generalized adaptation of the perceptual linear prediction model, popular in human speech processing, which incorporates perceptual information such as frequency warping and equal loudness normalization into the feature extraction process. Since such perceptual information is available for a number of animal species, this new approach integrates that information into a generalized model to extract perceptually relevant features for a particular species. To illustrate, qualitative and quantitative comparisons are made between the species-specific model, generalized perceptual linear prediction (gPLP), and the original PLP model using a set of vocalizations collected from captive African elephants (Loxodonta africana) and wild beluga whales (Delphinapterus leucas). The models that incorporate perceptional information outperform the original human-based models in both visualization and classification tasks.
Point-to-point underwater acoustic communications using spread-spectrum passive phase conjugation
Authors: Hursky Paul , Porter Michael B. , Siderius Martin , McDonald Vincent K.
Published: September 2006

The ocean is often a complex multipath channel and progress has been made in developing equalization algorithms to overcome this. Unfortunately, many of these algorithms are computationally demanding and not as power-efficient as one would like; in many applications it may be better to trade bit rate for longer operational life. In 2000 the U.S. Navy was developing an underwater wireless acoustic network called Seaweb, for which a number of modulation schemes were being tested in a series of SignalEx experiments. This paper discusses two modulation schemes and associated receiver algorithms that were developed and tested for Seaweb applications. These receiver designs take advantage of time reversal (phase conjugation) and properties of spread spectrum sequences known as Gold sequences. Furthermore, they are much less complex than receivers using adaptive equalizers. This paper will present results of testing these signaling and receiver concepts during two experiments at sea.
Low-level otoacoustic emissions may predict susceptibility to noise-induced hearing loss
Authors: Lapsley Miller Judi A. , Marshall Lynne , Heller Laurie M. , Hughes Linda M.
Published: September 2006

In a longitudinal study with 338 volunteers, audiometric thresholds and otoacoustic emissions were measured before and after 6 months of noise exposure on an aircraft carrier. While the average amplitudes of the otoacoustic emissions decreased significantly, the average audiometric thresholds did not change. Furthermore, there were no significant correlations between changes in audiometric thresholds and changes in otoacoustic emissions. Changes in transient-evoked otoacoustic emissions and distortion-product otoacoustic emissions were moderately correlated. Eighteen ears acquired permanent audiometric threshold shifts. Only one-third of those ears showed significant otoacoustic emission shifts that mirrored their permanent threshold shifts. A Bayesian analysis indicated that permanent threshold shift status following a deployment was predicted by baseline low-level or absent otoacoustic emissions. The best predictor was transient-evoked otoacoustic emission amplitude in the 4-kHz half-octave frequency band, with risk increasing more than sixfold from approximately 3% to 20% as the emission amplitude decreased. It is possible that the otoacoustic emissions indicated noise-induced changes in the inner ear, undetected by audiometric tests. Otoacoustic emissions may therefore be a diagnostic predictor for noise-induced-hearing-loss risk.
Temporal onset-order discrimination through the tactual sense: Effects of frequency and site of stimulation
Authors: Yuan Hanfeng , Reed Charlotte M. , Durlach Nathaniel I.
Published: September 2006

This research extends the study of temporal resolution of the tactual sensory system through measurements of temporal-onset order discrimination for continuous tonal signals addressing (a) the effects of frequency separation of the two stimuli whose onset orders are to be discriminated and (b) the effects of redundant coding of frequency and site of stimulation on performance. Sinusoidal signals were presented either at two separate digits (thumb and index finger of the left hand) or at a single site of stimulation (left index finger) using a multifinger tactual stimulation system. Measurements were obtained using a one-interval two-alternative forced choice procedure in which each interval consisted of the random-order presentation of two different stimuli with roving values of amplitude and duration. Thresholds were estimated from psychometric functions of d′ as a function of stimulus-onset asynchrony (SOA). On average, temporal onset-order thresholds were larger for one-finger conditions (mean SOA of 74.8ms) than for two-finger conditions (mean SOA of 48.5ms) and decreased as frequency separation increased, particularly for single-site presentation. Redundant coding of frequency and site of stimulation resulted in higher resolution by a factor of 1.5 compared to frequency alone and by a factor of 1.2 compared to site alone.
Pitch-based monaural segregation of reverberant speech
Authors: Roman Nicoleta , Wang DeLiang
Published: September 2006

In everyday listening, both background noise and reverberation degrade the speech signal. Psychoacoustic evidence suggests that human speech perception under reverberant conditions relies mostly on monaural processing. While speech segregation based on periodicity has achieved considerable progress in handling additive noise, little research in monaural segregation has been devoted to reverberant scenarios. Reverberation smears the harmonic structure of speech signals, and our evaluations using a pitch-based segregation algorithm show that an increase in the room reverberation time causes degraded performance due to weakened periodicity in the target signal. We propose a two-stage monaural separation system that combines the inverse filtering of the room impulse response corresponding to target location and a pitch-based speech segregation method. As a result of the first stage, the harmonicity of a signal arriving from target direction is partially restored while signals arriving from other directions are further smeared, and this leads to improved segregation. A systematic evaluation of the system shows that the proposed system results in considerable signal-to-noise ratio gains across different conditions. Potential applications of this system include robust automatic speech recognition and hearing aid design.
High intensity focused ultrasound-induced gene activation in solid tumors
Authors: Liu Yunbo , Kon Takashi , Li Chuanyuan , Zhong Pei
Published: September 2006

In this work, the activation of heat-sensitive trans-gene by high-intensity focused ultrasound (HIFU) in a tumor model was investigated. 4T1 cancer cells (2×106) were inoculated subcutaneously in the hind limbs of Balb/C mice. The tumors were subsequently transducted on day 10 by intratumoral injection of a heat-sensitive adenovirus vector (Adeno-hsp70B-Luc at 2×108pfu/tumor). On day 11, the tumors were heated to a peak temperature of 55, 65, 75, or 85°C within 10–30s at multiple sites around the center of the tumor by a 1.1- or 3.3-MHz HIFU transducer. Inducible luciferase gene expression was increased from 15-fold to 120-fold of the control group following 1.1-MHz HIFU exposure. Maximum gene activation (120-fold) was produced at a peak temperature of 65–75°C one day following HIFU exposure and decayed to baseline within 7 days. HIFU-induced gene activation (75°C-10s) could be further improved by using a 3.3-MHz transducer and a dense scan strategy to 170-fold. Thermal stress, rather than nonthermal mechanical stress, was identified as the primary physical mechanism for HIFU-induced gene activation in vivo. Overall, these observations open up the possibility for combining HIFU thermal ablation with heat-regulated gene therapy for cancer treatment.
Speech feature extraction method using subband-based periodicity and nonperiodicity decomposition
Authors: Ishizuka Kentaro , Nakatani Tomohiro , Minami Yasuhiro , Miyazaki Noboru
Published: September 2006

This paper proposes a speech feature extraction method that utilizes periodicity and nonperiodicity for robust automatic speech recognition. The method was motivated by the auditory comb filtering hypothesis proposed in speech perception research. The method divides input signals into subband signals, which it then decomposes into their periodic and nonperiodic components using comb filters independently designed in each subband. Both features are used as feature parameters. This representation exploits the robustness of periodicity measurements as regards noise while preserving the overall speech information content. In addition, periodicity is estimated independently in each subband, providing robustness as regards noise spectrum bias. The framework is similar to that of a previous study [Jackson et al., Proc. of Eurospeech. (2003), pp. 2321–2324], which is based on cascade processing motivated by speech production. However, the proposed method differs in its design philosophy, which is based on parallel distributed processing motivated by speech perception. Continuous digit speech recognition experiments in the presence of noise confirmed that the proposed method performs better than conventional methods when the noise in the training and test data sets differs.
On the sound field of a resilient disk in an infinite baffle
Authors: Mellow Tim
Published: September 2006

The Rayleigh integral describing the near-field pressure of an axisymmetric planar monopole source with an arbitrary velocity distribution is solved with a method similar to that used by Mast and Yu [J. Acoust. Soc. Am. 118(6), 3457–3464 (2005)] for a rigid disk in an infinite baffle. The closed-form solution is in the form of a double expansion, which is valid for distances from the observation point to the center of the source that are greater than its radius. However, for the remaining immediate near field, the King integral is solved using a combination of Gegenbauer’s summation theorem and the Lommel expansion, resulting in a solution which is in the form of a triple expansion, reducing to a double expansion along the source’s axis of symmetry. These relatively compact solutions in analytic form do not require numerical integration and therefore present no numerical difficulties except for a singularity at the rim. As an example of a monopole source with an arbitrary velocity distribution, equations describing the radiation characteristics of a resilient disk in an infinite baffle are derived. Using Babinet’s principle, the pressure field of a plane wave passing through the complementary hole in an infinite rigid screen is calculated.
A scanning laser Doppler vibrometer acoustic array
Authors: Cray Benjamin A. , Forsythe Stephen E. , Hull Andrew J. , Estes Lee E.
Published: September 2006

Experiments confirm that a laser Doppler vibrometer can be used to detect acoustic particle velocity on a fluid-loaded acoustically compliant, optically reflective surface. In these experiments, which were completed at the Acoustic Test Facility of the Naval Undersea Warfare Center, Scotchgard™ reflective tape was affixed to the interior surface of a standard acoustic window. The polyurethane array window had a thickness of 0.9525cm (0.375in.) and a material density of 1000kg∕m3. The surface velocity measured, using a commercial scanning laser vibrometer system (SLVS), was beamformed conventionally and flawlessly detected and localized acoustic signals. However, the laser Doppler vibrometer used in the experiments had relatively poor acoustic sensitivity, presumably due to high electronic noise in the photodetector, speckle noise, standoff distance, and drifting laser focus. An improved laser Doppler vibrometer, the simplified Michelson interferometer laser vibrometer sensor (SMIV), is described in brief. The SMIV achieves sensitivity of 61dB∕μPa in a 1-Hz band at 11.2kHz, which represents a 39-dB acoustic sensitivity improvement.
The violin bridge as filter
Authors: Bissinger George
Published: September 2006

The violin bridge filter role was investigated using modal and acoustic measurements on 12 quality-rated violins combined with systematic bridge rocking frequency frock and wing mass decrements Δm on four bridges for two other violins. No isolated bridge resonances were observed; bridge motions were complex (including a “squat” mode near 0.8kHz) except for low frequency rigid body pivot motions, all more or less resembling rocking motion at higher frequencies. A conspicuous broad peak near 2.3kHz in bridge driving point mobility (labeled BH) was seen for good and bad violins. Similar structure was seen in averaged bridge, bridge feet, corpus mobilities and averaged radiativity. No correlation between violin quality and BH driving point, averaged corpus mobility magnitude, or radiativity was found. Increasing averaged-over-frockΔm(g) from 0 to 0.12 generally increased radiativity across the spectrum. Decreasing averaged-over-Δm frock from 3.6 to 2.6kHz produced consistent decreases in radiativity between 3 and 4.2kHz, but only few-percent decreases in BH frequency. The lowest frock values were accompanied by significantly reduced radiation from the Helmholtz A0 mode near 280Hz; this, combined with reduced high frequency output, created overall radiativity profiles quite similar to “bad” violins among the quality-rated violins.
Dual-electrode pitch discrimination with sequential interleaved stimulation by cochlear implant users
Authors: Kwon Bom Jun , van den Honert Chris
Published: September 2006

Cochlear implant users may perceive intermediate place-pitches between those elicited by the individual electrodes when two electrodes are stimulated simultaneously or sequentially. This study examined pitch discrimination between adjacent electrodes using sequential dual-electrode stimulation in terms of the sensitivity index, d′, which was obtained by adding d′s from intermediate dual-electrode stimuli. Loudness was balanced for each tested pair and the intensities were roved. Twelve ears with the Nucleus® 24 or Freedom implants demonstrated a wide range of d′, from 0.7 to 9.6. “Virtual channels” can be implemented through nonsimultaneous stimulation, with comparable pitch discrimination to that observed with simultaneous stimulation.
An effective cluster-based model for robust speech detection and speech recognition in noisy environments
Authors: Górriz J. M. , Ramírez J. , Segura J. C. , Puntonet C. G.
Published: September 2006

This paper shows an accurate speech detection algorithm for improving the performance of speech recognition systems working in noisy environments. The proposed method is based on a hard decision clustering approach where a set of prototypes is used to characterize the noisy channel. Detecting the presence of speech is enabled by a decision rule formulated in terms of an averaged distance between the observation vector and a cluster-based noise model. The algorithm benefits from using contextual information, a strategy that considers not only a single speech frame but also a neighborhood of data in order to smooth the decision function and improve speech detection robustness. The proposed scheme exhibits reduced computational cost making it adequate for real time applications, i.e., automated speech recognition systems. An exhaustive analysis is conducted on the AURORA 2 and AURORA 3 databases in order to assess the performance of the algorithm and to compare it to existing standard voice activity detection (VAD) methods. The results show significant improvements in detection accuracy and speech recognition rate over standard VADs such as ITU-T G.729, ETSI GSM AMR, and ETSI AFE for distributed speech recognition and a representative set of recently reported VAD algorithms.
Effects of vocal loudness variation on spectrum balance as reflected by the alpha measure of long-term-average spectra of speech
Authors: Sundberg Johan , Nordenberg Maria
Published: September 2006

The overall slope of long-term-average spectrum (LTAS) decreases if vocal loudness increases. Therefore, changes of vocal loudness also affects the α measure, defined as the ratio of spectrum intensity above and below 1000Hz. The effect on α of loudness variation was analyzed in 15 male and 16 female voices reading a text at different degrees of vocal loudness. The mean range of equivalent sound level (Leq) amounted to about 28dB and the mean range of α to 19.0 and 11.7dB for the female and male subjects. The Leq vs. α relationship could be approximated with a quadratic function, or by a linear equation, if softest phonation was excluded. Using such equations α was computed for all values of Leq observed for each subject and compared with observed values. The maximum and the mean absolute errors were 2.4dB and between 0.1 and 0.6dB. When softest phonation was disregarded and linear equations were used, the maximum error was less than 2dB and the mean absolute errors were between 0.2 and 0.7dB. The strong correlation between Leq and α indicates that for a voice Leq can be used for predicting α.
Consistency and reliability of geoacoustic inversions with a horizontal line array
Authors: Fialkowski Laurie T. , Yang T. C. , Yoo Kwang , Kim Elisabeth , Dacol Dalcio K.
Published: September 2006

Geoacoustic inversions with a towed horizontal array are of interest for rapidly characterizing sediment properties over changing regions. To be of practical value, inversions must yield consistent and reliable results for consecutive or neighboring data. A method of determining inversion reliability a priori is delineated using an empirical approach and confirmed with inversion results in terms of consistency. Geoacoustic parameter hierarchy and resolvability are empirically analyzed using two different methods: one requires knowledge of the source function and the other does not. Inversion results using the two methods are compared using both synthetic data and experimental data from MAPEX2000. The inversions employ a global optimization technique which navigates the parameter space in directions aligned with valleys of the cost function, increasing inversion algorithm efficiency and disclosing parameter correlations and hierarchy.
Design and performance of a microprobe attachment for a 12-in. microphone
Authors: Daigle Gilles A. , Stinson Michael R.
Published: September 2006

It is often necessary to measure sound fields in confined spaces where minimum disturbance of the sound field is important. In applications where the confinement of the space is extreme such as very small cavities, existing probe microphones are too large. In this paper the probe section of a Brüel and Kjær probe microphone type 4170 is redesigned using smaller diameter probe tubes. New designs (microprobes) are first considered through simulations in the case of probe tubes having inside diameters ranging from 1.25 down to 0.1mm. Several microprobes were constructed and their performance measured and compared to the simulated results. Good agreement was found between the measured and simulated frequency response and sensitivity. Measurements show that a sensitivity of about 0.02mV∕Pa could be obtained from a probe tube with 0.2mm o.d. and 0.1mm i.d. if the length is less than 1cm. The input impedance of the probe orifice is estimated to be greater than 3×1010kgs−1m−4. Viscous resistance and thermal conduction due to the small diameter provides a well-behaved frequency response that is flat within 5dB between 200 and 6000Hz and to within 12dB up to 10000Hz.
Comparative Genomic Evidence for a Close Relationship between the Dimorphic Prosthecate Bacteria
Hyphomonas neptunium
and
Caulobacter crescentus
Authors: Badger Jonathan H. , Hoover Timothy R. , Brun Yves V. , Weiner Ronald M. , Laub Michael T. , Alexandre Gladys , Mrázek Jan , Ren Qinghu , Paulsen Ian T. , Nelson Karen E. , Khouri Hoda M. , Radune Diana , Sosa Julia , Dodson Robert J. , Sullivan Steven A. , Rosovitz M. J. , Madupu Ramana , Brinkac Lauren M. , Durkin A. Scott , Daugherty Sean C. , Kothari Sagar P. , Giglio Michelle Gwinn , Zhou Liwei , Haft Daniel H. , Selengut Jeremy D. , Davidsen Tanja M. , Yang Qi , Zafar Nikhat , Ward Naomi L.
Published: September 2006

The dimorphic prosthecate bacteria (DPB) are α-proteobacteria that reproduce in an asymmetric manner rather than by binary fission and are of interest as simple models of development. Prior to this work, the only member of this group for which genome sequence was available was the model freshwater organism
Caulobacter crescentus
. Here we describe the genome sequence of
Hyphomonas neptunium
, a marine member of the DPB that differs from
C. crescentus
in that
H. neptunium
uses its stalk as a reproductive structure. Genome analysis indicates that this organism shares more genes with
C. crescentus
than it does with
Silicibacter pomeroyi
(a closer relative according to 16S rRNA phylogeny), that it relies upon a heterotrophic strategy utilizing a wide range of substrates, that its cell cycle is likely to be regulated in a similar manner to that of
C. crescentus
, and that the outer membrane complements of
H. neptunium
and
C. crescentus
are remarkably similar.
H. neptunium
swarmer cells are highly motile via a single polar flagellum. With the exception of
cheY
and
cheR
, genes required for chemotaxis were absent in the
H. neptunium
genome. Consistent with this observation,
H. neptunium
swarmer cells did not respond to any chemotactic stimuli that were tested, which suggests that
H. neptunium
motility is a random dispersal mechanism for swarmer cells rather than a stimulus-controlled navigation system for locating specific environments. In addition to providing insights into bacterial development, the
H. neptunium
genome will provide an important resource for the study of other interesting biological processes including chromosome segregation, polar growth, and cell aging.
Whole-Genome Transcriptional Analysis of Chemolithoautotrophic Thiosulfate Oxidation byThiobacillus denitrificansunder Aerobic versus Denitrifying Conditions
Authors: Beller Harry R. , Letain Tracy E. , Chakicherla Anu , Kane Staci R. , Legler Tina C. , Coleman Matthew A.
Published: September 2006

Thiobacillus denitrificansis one of the few known obligate chemolithoautotrophic bacteria capable of energetically coupling thiosulfate oxidation to denitrification as well as aerobic respiration. As very little is known about the differential expression of genes associated with key chemolithoautotrophic functions (such as sulfur compound oxidation and CO2fixation) under aerobic versus denitrifying conditions, we conducted whole-genome, cDNA microarray studies to explore this topic systematically. The microarrays identified 277 genes (approximately 10% of the genome) as differentially expressed using RMA (robust multiarray average) statistical analysis and a twofold cutoff. Genes upregulated (ca. 6- to 150-fold) under aerobic conditions included a cluster of genes associated with iron acquisition (e.g., siderophore-related genes), a cluster of cytochromecbb3oxidase genes,cbbLandcbbS(encoding the large and small subunits of form I ribulose 1,5-bisphosphate carboxylase/oxygenase, or RubisCO), and multiple molecular chaperone genes. Genes upregulated (ca. 4- to 95-fold) under denitrifying conditions includednar,nir, andnorgenes (associated, respectively, with nitrate reductase, nitrite reductase, and nitric oxide reductase, which catalyze successive steps of denitrification),cbbM(encoding form II RubisCO), and genes involved with sulfur compound oxidation (including two physically separated but highly similar copies of sulfide:quinone oxidoreductase and ofdsrC, associated with dissimilatory sulfite reductase). Among genes associated with denitrification, relative expression levels (i.e., degree of upregulation with nitrate) tended to decrease in the ordernar>nir>nor>nos. Reverse transcription-quantitative PCR analysis was used to validate these trends.
Lipoprotein PssN of
Rhizobium leguminosarum
bv. trifolii: Subcellular Localization and Possible Involvement in Exopolysaccharide Export
Authors: Marczak Małgorzata , Mazur Andrzej , Król Jarosław E. , Gruszecki Wiesław I. , Skorupska Anna
Published: September 2006

Surface expression of exopolysaccharides (EPS) in gram-negative bacteria depends on the activity of proteins found in the cytoplasmic membrane, the periplasmic space, and the outer membrane.
pssTNOP
genes identified in
Rhizobium leguminosarum
bv. trifolii strain TA1 encode proteins that might be components of the EPS polymerization and secretion system. In this study, we have characterized PssN protein. Employing
pssN
-
phoA
and
pssN
-
lacZ
gene fusions and in vivo acylation with [
3
H]palmitate, we demonstrated that PssN is a 43-kDa lipoprotein directed to the periplasm by an N-terminal signal sequence. Membrane detergent fractionation followed by sucrose gradient centrifugation showed that PssN is an outer membrane-associated protein. Indirect immunofluorescence with anti-PssN and fluorescein isothiocyanate-conjugated antibodies and protease digestion of spheroplasts and intact cells of TA1 provided evidence that PssN is oriented towards the periplasmic space. Chemical cross-linking of TA1 and
E. coli
cells overproducing PssN-His
6
protein showed that PssN might exist as a homo-oligomer of at least two monomers. Investigation of the secondary structure of purified PssN-His
6
protein by Fourier transform infrared spectroscopy revealed the predominant presence of β-structure; however, α-helices were also detected. Influence of an increased amount of PssN protein on the TA1 phenotype was assessed and correlated with a moderate enhancement of EPS production.