Auditory-phonetic projection and lexical structure in the recognition of sine-wave words.

Speech remains intelligible despite the elimination of canonical acoustic correlates of phonemes from the spectrum. A portion of this perceptual flexibility can be attributed to modulation sensitivity in the auditory-to-phonetic projection, although signal-independent properties of lexical neighborhoods also affect intelligibility in utterances composed of words. Three tests were conducted to estimate the effects of exposure to natural and sine-wave samples of speech in this kind of perceptual versatility. First, sine-wave versions of the easy and hard word sets were created, modeled on the speech samples of a single talker. The performance difference in recognition of easy and hard words was used to index the perceptual reliance on signal-independent properties of lexical contrasts. Second, several kinds of exposure produced familiarity with an aspect of sine-wave speech: (a) sine-wave sentences modeled on the same talker; (b) sine-wave sentences modeled on a different talker, to create familiarity with a sine-wave carrier; and (c) natural sentences spoken by the same talker, to create familiarity with the idiolect expressed in the sine-wave words. Recognition performance with both easy and hard sine-wave words improved after exposure only to sine-wave sentences modeled on the same talker. Third, a control test showed that signal-independent uncertainty is a plausible cause of differences in recognition of easy and hard sine-wave words. The conditions of beneficial exposure reveal the specificity of attention underlying versatility in speech perception. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A pilot study of recombinant interleukin-2 for treatment of chronic hepatitis C

The optimal and safer interleukin-2 (IL-2) dose for treatment of chronic hepatitis C virus (HCV) infection has been studied in 33 HCV-RNA positive patients with chronic hepatitis C. Patients were randomly allocated to receive 5 days per week during 12 weeks IL-2 doses of: 0.9 MIU (n = 10), 1.8 MIU (n = 10), or 3.6 MIU (n = 13). After 12 weeks, responder patients stopped treatment, whereas nonresponders received 12 additional weeks of IL-2 at the next higher dose: 1.8, 3.6, or 5.4 MIU. As a whole, after the first 12 weeks of IL-2 alanine aminotransferase (ALT) levels significantly decreased (P < .001) with respect to the baseline values (140 +/- 63 vs. 70 +/- 30 IU/L). At the end of treatment (24 weeks), the mean ALT level (80 +/- 50 IU/L) continued significantly lower (P < .001) than the baseline one, and 24% of patients normalized ALT levels; according to dosage, ALT normalization was: 0% for 0.9 MIU, 25% for 1.8 MIU, 5% for 3.6 MIU, and 18% for 5.4 MIU. HCV-RNA levels decreased during treatment, but in none of the patients became undetectable. All patients had a local reaction at the injection site with induration, erythema, and swelling, which was dose-related. The dose of 5.4 MIU was poorly tolerated and was reduced to 3.6 MIU in 4 of 11 patients. No changes in hematological parameters were observed. At the end of follow-up (6 months) four of eight responder patients continued with normal ALT. In conclusion, IL-2 treatment for chronic hepatitis C induced a biochemical response in 8 of 33 (24%) patients at the end of therapy while at the end of follow-up, 4 of 33 (8%) patients remained with normal ALT. The dose of 1.8 MIU is well tolerated and seems to be the most efficacious.     

Demagnetizing factors for square bars

Using a finite-element method, we have calculated fluxmetric and magnetometric demagnetizing factors N/sub f/ and N/sub m/ for square cross-section bars as functions of susceptibility /spl chi/ and length-to-width ratio c/a over the range /spl chi/=-1 to /spl infin/ and c/a=0.01 to 100. We present the results in figures and tables and compare them with those for cylinders. We give an approximate conjugate relation for N/sub m/(/spl chi/) of a cube.     

Experimental and theoretical study of ultrafast optical switching using guided mode excitation in silicon on sapphire

A silicon film sandwiched between a sapphire substrate and a silver layer is used as nonlinear optical waveguide. Light is coupled in the guide by a grating coupler which has been optimized. This device presents fast switchings under a nonlinear regime. A theoretical analysis taking into account both electronic and thermal refractive index variations in silicon well describes the experimental results.     

Prediction of weld pool and reinforcement dimensions of GMA welds using a finite-element model

Mathematical models of the gas metal arc (GMA) welding process may be used to study the influence of various welding parameters on weld dimensions, to assist in the development of welding procedures, and to aid in the generation of process control algorithms for automated applications. In this work, a three-dimensional (3-D), steady-state thermal model of the GMA welding process has been formulated for a moving coordinate framework and solved using the finite-element method. The model includes temperature-dependent material properties, a new finite-element formulation for the inclusion of latent heat of fusion, a Gaussian distribution of heat flux from the arc, plus the effects of mass convection into the weld pool from the melted filler wire. The influence of weld pool convection on the pool shape was approximated using anisotropically enhanced thermal conductivity for the liquid phase. Weld bead width and reinforcement height were predicted using a unique iterative technique developed for this purpose. In this paper, the numerical model is shown to be capable of predicting GMA weld dimensions for individual welds, including those with finger penetration. Also, good agreement is demonstrated between predicted weld dimensions and experimentally derived relations that describe the effects of process variables and their influence on average weld dimensions for bead-onplate GMA welds on steel plate. E. PARDO, formerly Postdoctoral Fellow, Department of Mechanical Engineering, University of Waterloo, Waterloo, ON, Canada N2L 3G1,     

Urinary excretion of free and acetylated polyamines in hepatocellular carcinoma

Bone mineral density (BMD), and associated biochemical and endocrine markers were compared in a group of runners with menstrual dysfunction (IR, n=13), and a group of performance matched eumenorrheic runners (R, n=15). All subjects claimed to have normal eating habits. Body height and weight, body mass index, and amount of body fat were similar. The IR group consisted of 5 presently oligomenorrheic (O) and 8 presently amenorrheic (A) runners. The BMD values of the athletes were additionally compared with corresponding values in a reference group (C) of healthy age matched controls (n=54). BMD values were significantly lower in IR compared with R on all measuring sites: Total body (-9%, p=0.03), femoral neck (-11%, p=0.01), lumbar spine (-12%, p=0.001), lower leg (-6.5%, p=0.03) and arms (-7%, p=0.01). In addition, IR athletes had lower total body (-5%, p=0.01), and lumbar spine BMD (-10%, p=0.001) than C. No differences were observed in serum IGF-1, SHBG, testosterone and cortisol, or in the biochemical marker of bone formation (osteocalcin) and bone resorption (1 CTP). Values of serum E2, FSH and LH were low in IR and normal in R. TSH was in the normal range in both groups, but f-T4 was significantly lower in IR than in R. The athletes were furthermore grouped according to past and present menstrual dysfunction severity. At all measuring sites, with the exception of the lower leg, increasing menstrual dysfunction severity was linearly associated with declining BMD values (p<0.05). In conclusion, even highly conditioned cortical bone tissue seems to be negatively related to menstrual disorders, which may serve to explain the high incidence of stress fractures in athletes with menstrual disorders. Single measurements of biochemical markers of bone resorption and formation may not reflect the current bone status.     

Altered ligand dissociation rates in thyrotropin-releasing hormone receptors mutated in glutamine 105 of transmembrane helix III

Glutamine 105 in the third transmembrane helix of the thyrotropin-releasing hormone receptor (TRH-R) occupies a position equivalent to a conserved negatively charged residue in receptors for biogenic amines where it acts as counterion interacting with the cationic amine moiety of the ligand. Maximum levels of response to TRH in oocytes expressing wild-type TRH-Rs were indistinguishable from those of oocytes expressing receptors mutated to Glu, Asn, or Asp in position 105. However, the EC50 values for activation of oocyte responses increased more than 500 times in oocytes expressing mutant Glu105 receptors, in which the amido group of Gln105 has been removed by site-directed mutagenesis. Charge effects do not seem to be involved in the huge effect of mutating Gln105 to Glu, since mutation of Gln105 to Asp induces only a 15-fold increase in EC50. Furthermore, no change in EC50 is observed after mutation of Asn110 to Asp. The affinity shift (identified by changes in EC50 values for systems of comparable efficacy) in Glu105 mutant receptors was partially recovered in oocytes expressing Asn105 mutant receptors. These results and those obtained after substitution of Lys, Leu, Tyr, and Ser for Gln105 suggest that the presence and the correct position of the Gln hydrogen bond-donor amido group are important for normal functionality of the receptor. In wild type or Asp105 mutant receptors showing the same maximal responses, decreases in affinity with TRH and methyl-histidyl-TRH correlated with increased dissociation rates of hormone from the receptor. Rapid dilution experiments following subsecond stimulation indicate that the TRH-R is converted rapidly from a form showing fast dissociation kinetics to a form from which the hormone dissociates slowly. Mutation of residue 105 impairs the receptor shift between these two forms. This effect was demonstrated in a direct way by comparing [3H]methyl-histidyl-TRH dissociation rates in COS-7 cells transfected with either wild type or Asp105 mutant TRH-Rs. Thus, residues located in transmembrane helix III positions equivalent to those of the counterions for biogenic amines, regulate hormone-receptor interactions in the TRH receptor (and perhaps other receptors). Furthermore, the nature of the amino acid in these positions may also play a role, directly or indirectly, in conformational changes leading to receptor activation, and hence to signal transduction.     

Ferropiezoelectricity of calcium modified lead titanate ceramics

When a ceramic with grain Boundaries rich in OPb is poled Beyond 4O kV cm^–1 at ferroelectric phase, the highest anisotropy of electromechanical coupling factor is obtained. An attempt to explain this Behaviour is made in terms of domain switching and the strains and cracks generated during cooling down poling. Apart from composition, two more factors are revealed as contributing to the disappearance of radial coupling in Ca-modified lead titanate ceramics: microtexture and electric poling strategy.     

Binocular mechanisms mediating crossed and uncrossed stereopsis.

Discusses empirical evidence in support of the notion that the encoding of stereoscopic information may be based on the differential output of disparity detectors that are tuned to different disparity directions (i.e., crossed and uncrossed). Findings demonstrate that the direction of retinal disparity (whether a stimulus carries a crossed or uncrossed disparity) seems to be critical to the manner in which stereoscopic information is processed by the visual system. Data also suggest that crossed disparities are processed more readily and perhaps more efficiently than uncrossed disparities. Data further suggest that information about crossed and uncrossed disparity may be organized into separate pools or classes of cells that have different sensitivities, different spatial properties, and different temporal constants. (87 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)