Discrimination of Velocity and Spectral Composition of a Sound Stimulus during Its Movement in the Vertical Plane

Differential sensitivity to the velocity of a sound source image in the vertical plane was studied by using two signals with different spectral bandwidths: 0.25–4 kHz (signal 1) and 4–12.5 kHz (signal 2). Five subjects were tested. Sequential switching of loudspeakers with similar frequency characteristics simulated movement of a sound source. Differential velocity thresholds were determined for two reference velocities: 58 and 115°/s. Significant differences in the absolute values of these thresholds were found for signals with different spectral compositions. The threshold for signal 1 (0.25–4.0 kHz) exceeded that for signal 2 (4.0–12.5 kHz) twofold at 58°/s and 1.6-fold at 115°/s.     

Reliability of Phase Velocity Measurements of Flexural Acoustic Waves in the Human Tibia In-Vivo

Purpose

Axial-transmission acoustics have shown to be a promising technique to measure individual bone properties and detect bone pathologies. With the ultimate goal being the in-vivo application of such systems, quantification of the key aspects governing the reliability is crucial to bring this method towards clinical use.

Materials and Methods

This work presents a systematic reliability study quantifying the sources of variability and their magnitudes of in-vivo measurements using axial-transmission acoustics. 42 healthy subjects were measured by an experienced operator twice per week, over a four-month period, resulting in over 150000 wave measurements. In a complementary study to assess the influence of different operators performing the measurements, 10 novice operators were trained, and each measured 5 subjects on a single occasion, using the same measurement protocol as in the first part of the study.

Results

The estimated standard error for the measurement protocol used to collect the study data was ∼ 17 m/s (∼ 4% of the grand mean) and the index of dependability, as a measure of reliability, was Φ = 0.81. It was shown that the method is suitable for multi-operator use and that the reliability can be improved efficiently by additional measurements with device repositioning, while additional measurements without repositioning cannot improve the reliability substantially. Phase velocity values were found to be significantly higher in males than in females (p < 10⁻⁵) and an intra-class correlation coefficient of r = 0.70 was found between the legs of each subject.

Conclusions

The high reliability of this non-invasive approach and its intrinsic sensitivity to mechanical properties opens perspectives for the rapid and inexpensive clinical assessment of bone pathologies, as well as for monitoring programmes without any radiation exposure for the patient.     

Keratocyte Fragments and Cells Utilize Competing Pathways to Move in Opposite Directions in an Electric Field

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Highlights? A cell fragment is the simplest motile electric-field-sensing unit ? Keratocyte cells and fragments migrate in opposite directions in an electric field ? Competition of two signal transduction pathways underlies keratocyte galvanotaxis ? Protrusive and contractile actin networks are steered by the electric field     

Functional Asymmetry at Evaluation of Movement Trajectory of the Solid Sound Image in Human

At studying localization by human of moving solid sound image (SSI) under conditions of dichotic stimulation, an asymmetry has been revealed in evaluation of a shift of the initial and final points of the opposite SSI movement under mirror-symmetry conditions of stimulation. The shift to the right in all cases exceeds that to the left (by 3.4–32.1 degrees). The most pronounced asymmetry is observed at the initial moment of the SSI movement at the synergism of interaural differences in stimulation by its time and intensity; under these conditions, the trajectory of the SSI movement to the left turns out to be about 1.8 times longer than the movement to the right. Possible neurophysiological mechanisms of the obtained results are considered.     

Acoustic Features Used in Song Discrimination by the Veery

To investigate which song features are used for discrimination by the veery (Catharus fuscescens), we synthesized songs by computer and manipulated or deleted various features. These songs were then played to territorial males in their natural habitat. Differences in response to these stimuli indicated the relative importance of the manipulated song components. We found that certain features must be maintained in order to elicit a territorial response similar to that elicited by the natural song. These features were the frequency changes between and within syllables, the dominant higher frequency band (or voice), the intra-syllable syntax, and the rapid repetitive amplitude and frequency modulations. Manipulations of inter-syllable syntax independent of frequency changes between syllables, broad changes in amplitude, and the lower frequency band, did not have a significant effect on response. We thus concluded that they are not essential as cues for discrimination or species identification. Re-recordings of songs broadcast along transects indicate that song components used in encoding species identity are those which transmit well across veery territories.     

Subjective Acoustic Field of Patients with Cortical Temporal Lobe Epilepsy as Revealed Using Signals Simulating Various Directions of Sound Movement

Perception of signals simulating directional movement of a sound source was studied in two groups of patients with cortical temporal lobe epilepsy and epileptic activity foci in the right or left temporal area of the cortex. On dichotic stimulation, the character and length of the trajectories of subjective auditory images (SAIs) were determined as dependent on the direction of SAI movement and the initial interaural delay (700, 400, and 200 s). For any delay or direction examined, SAI trajectories were shorter in the patients of both groups than in healthy subjects. Regardless of the side of an epileptic focus, the shortest trajectories were detected in the hemisphere where SAI movement ended, especially at an interaural delay of 200 s. The narrowest subjective acoustic field was observed in patients with epileptic foci in the right temporal cortex. Possible mechanisms of the changes in spatial hearing are discussed. The changes in SAI perception are assumed to result from distorted binaural interactions, which manifest themselves in functional asymmetry of the two auditory centers and may be caused by a convulsive activity focus present in one temporal lobe.     

Short-Term Fidelity,Habitat Use and Vertical Movement Behavior of the Black Rockfish Sebastes schlegelii as Determined by Acoustic Telemetry

The recent miniaturization of acoustic tracking devices has allowed fishery managers and scientists to collect spatial and temporal data for sustainable fishery management. The spatial and temporal dimensions of fish behavior (movement and/or vertical migrations) are particularly relevant for rockfishes (Sebastes spp.) because most rockfish species are long-lived and have high site fidelity, increasing their vulnerability to overexploitation. In this study, we describe the short-term (with a tracking period of up to 46 d) spatial behavior, as determined by acoustic tracking, of the black rockfish Sebastes schlegelii, a species subject to overexploitation in the Yellow Sea of China. The average residence index (the ratio of detected days to the total period from release to the last detection) in the study area was 0.92 ± 0.13, and most of the tagged fish were detected by only one region of the acoustic receiver array, suggesting relatively high site fidelity to the study area. Acoustic tracking also suggested that this species is more frequently detected during the day than at night in our study area. However, the diel detection periodicity (24 h) was only evident for certain periods of the tracking time, as revealed by a continuous wavelet transform. The habitat selection index of tagged S. schlegelii suggested that S. schlegelii preferred natural reefs, mixed sand/artificial reef bottoms and mixed bottoms of boulder, cobble, gravel and artificial reefs. The preference of this species for the artificial reefs that were recently deployed in the study area suggests that artificial seascapes may be effective management tools to attract individuals. The vertical movement of tagged S. schlegelii was mostly characterized by bottom dwelling behavior, and there was high individual variability in the vertical migration pattern. Our results have important implications for S. schlegelii catchability, the implementation of marine protected areas, and the identification of key species habitats, and our study provides novel information for future studies on the sustainability of this important marine resource in eastern China.     

Differential Vertical Movement of Nonvolatile Nematicides in Soil

When incorporated in the top 5-cm of Tifton sandy loam at 11.2 kg/ha in the field, B-68138 [ethyl 4-(methylthio)-m-tolyl isopropyl phosphoramidate] prevented galling of tomato roots by Meloidogyne sp. down to 20 cm. A similar application of 16.8 kg/ha of V-C 9-104 [0-ethyl S,S-dipropyl phosphorodithioate] was 99% effective down to 20 cm. Aldicarb [2-methyl-2-(methylthio) propionaldehyde 0-(methylcarbamoyl) oxime], B-25141 [0,0-diethyl 0-{p-(methylsulfinyl) phenyl}phosphorothioate], and carbofuran [2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate] prevented galling only in the zone of incorporation (top 5-cm of soil). When aldicarb (11.2 kg/ha) was applied to the surface of Ontario fine sandy loam contained in clay pots in the greenhouse, it prevented galling of tomato roots down to 20 cm deep. V-C 9-104 and B-68138, applied similarly, were 100% effective to a depth of 5 cm. B-25141 was 100% effective in the zone of incorporation only. D-1410 [S-methyl-l-(dimethylcarbamoyl)-N-l(methylcarbamoyl)oxy] thioformimidatel did not control 100% of the root-knot nematodes at any depth.     

Discrimination of Image Orientation in the Presence of Distractors

We studied the influence of additional images (distractors) on the recognition of test objects, which included low-contrast Landolt circles with sizes of 1.1, 1.5, and 2.2 angular degrees and were presented eccentrically at 13.2 degrees from fixation. The distractors were either Landolt Cs or full circles with the same spatial characteristics. The distance between the test objects and the distractors varied from 2.2 to 24.2 angular degrees. The subjects were required to report the orientation of the tests (simple task) or to report the orientation of the tests and the shape of the distractor (dual task). The first group of subjects performed both simple and dual tasks, while the second group only performed the simple task. A significant deterioration of performance was recorded at all tested separations in both tasks; it was more pronounced in the dual task. The percent of correct responses was lower when Landolt circles were distractors as compared with full circles. The subjects tended to report the orientation of the distractors instead of tests in the cases of small and large separations. The recognition of distractors was also performed at a lower level in the cases of small and large distances. The data show that attention contributes to the task performance in two ways: the features of tests and distractors are integrated, or the tests are substituted by distractors.     

Study of Human RIG-I Polymorphisms Identifies Two Variants with an Opposite Impact on the Antiviral Immune Response

Background

RIG-I is a pivotal receptor that detects numerous RNA and DNA viruses. Thus, its defectiveness may strongly impair the host antiviral immunity. Remarkably, very little information is available on RIG-I single-nucleotide polymorphisms (SNPs) presenting a functional impact on the host response.

Methodology/Principal Findings

Here, we studied all non-synonymous SNPs of RIG-I using biochemical and structural modeling approaches. We identified two important variants: (i) a frameshift mutation (P₂₂₉fs) that generates a truncated, constitutively active receptor and (ii) a serine to isoleucine mutation (S₁₈₃I), which drastically inhibits antiviral signaling and exerts a down-regulatory effect, due to unintended stable complexes of RIG-I with itself and with MAVS, a key downstream adapter protein.

Conclusions/Significance

Hence, this study characterized P₂₂₉fs and S₁₈₃I SNPs as major functional RIG-I variants and potential genetic determinants of viral susceptibility. This work also demonstrated that serine 183 is a residue that critically regulates RIG-I-induced antiviral signaling.     

Measurement of Horizontal and Vertical Movement of Ralstonia solanacearum in Soil

Two model systems were constructed to measure horizontal and vertical movement of bacteria in soil. These systems were applied to measuring movement of Ralstonia solanacearum (race 1, biovar 3), a causal agent of bacterial wilt of tomato, in andosol and sand at 28°C. The first system was used to measure horizontal movement of the bacteria in soil packed in a narrow horizontal frame. Suspension of the pathogen was applied to soil at one end of the frame, and bacterial number per gram of soil was measured over distance from the inoculation point after 4 days. Horizontal movement of R. solanacearum in supersaturated soil, but without flow, was possibly due to diffusion and the front advanced at 2.2 cm/day in andosol, and at 8.1 cm/day in sand. Using the same experimental system, but applying water inflow to one end of the frame only, the bacterium was detected at the front of water in andosol and sand. The front of the distribution advanced at 20.4 cm/h in andosol and 66.3 cm/h in sand. In the second experimental system, a cylinder of soil packed in a short tube was soaked with water, and soil at the top of the tube was inoculated with bacterial suspension. Immediately, soil cylinders were turned upward, and the bacterial number per gram of soil was measured along vertical distance from the inoculation point after 7 days. Using the system with andosol, the capillary water front rose to 32.5 cm over 7 days after inoculation, and R. solanacearum reached to 18.8 cm height. In sand, capillary water rose to 20.0 cm and the bacteria reached to 16.3 cm height.     

Efficiency of the Human Visual System in Discrimination of Dynamic Images

The efficiency of the human visual system during the observation of motionless test objects with additive dynamic Gaussian quasi-white noise was studied. It was found that the relationship between the duration of presentation of the object and the efficiency in presence of dynamic noise has a maximum at 20 ms. The presence of this maximum is explained by the simultaneous effects of two factors: (1) the limited duration of accumulation of visual memory and (2) the time necessary to develop decision-making thresholds during recognition. It was also shown that absence of prior information about the position of the target object reduces the efficiency more than absence of prior information about the time of its appearance.     

Differences in Velocity of Auxin Movement Obtained by Intercept and Peak Arrival Methods

Velocity of IAA movement was determined by noting the time of arrival of an ether-soluble auxin wave, at a fixed distance, after presentation of an auxin pulse to bean (Phaseolus vulgaris L. cv. Pinto) hypocotyl segments. The effects of IAA adsorption on wave symmetry were reduced by monitoring the arrival of ether-soluble auxin molecules. Velocity of auxin movement, as estimated by wave arrival, was slower than velocity estimated by the intercept method in controls and in both iodoacetate (IOAA) and 2,3,5-triiodobenzoic acid (TIBA) treated tissue. Velocity of wave migration was reduced by both treatments but intercept velocity was reduced only by TIBA treatment. Velocity of IAA migration was faster in segments (independent of method of measurement) than from segments into agar by a factor of 4 to 8. The rate limiting step of auxin migration in the traditional agar-plant sandwich is the partitioning of IAA between the tissue and agar. It was suggested that arrival curves for pulsed auxin migration are analogous to elution profiles of chromatographic columns and that at least two populations of mobile molecules with different velocities exist. It was also suggested that the two velocities represent migration of auxin on two different pathways: the faster velocity representing auxin movement of water films which coast highly crosslinked polymers in the segment and the slower component representing a population which moves primarily within the matrices of crosslinked polymers. Velocity of both populations may be a function of tissue hydration and charge interactions of mobile molecules and matrix polymers.     

Human Assessment of Signals Modeling Different Directions of the Motion of Sound Images

The characteristics of a subjective sound field formed under conditions of dichotic stimulation were studied in healthy subjects (six females and seven males) with normal auditory sensitivity upon movement of a sound image (SI) in different directions. The character and the trajectory values of the emerging subjective sound image (SSI) were determined depending on the direction of its motion and the initial interaural delay (700, 400, and 200 s). Certain differences in the assessment of the parameters of moving sound images between the groups of male and female subjects were revealed. In female subjects, the averaged trajectory values in the right and left hemispheres were the same when the SSI moved in both directions and shortened uniformly with a decrease in the initial interaural delay. With a 700-s delay, the trajectory values of the male subjects for all directions of motion of the SSI were the same as those of female subjects. With initial 400- and 200-s delays, the trajectory values were significantly greater in the group of male subjects if a SI moved from the right or left ear to the median line of the head. With the method used, no interhemispheric asymmetry was revealed in the process of lateralization of moving sound images, which, under certain conditions, may be of importance for increasing the accuracy of localization of sound sources in the environment.     

Structure and Regulation of the Movement of Human Myosin VIIA

Human myosin VIIA (HM7A) is responsible for human Usher syndrome type 1B, which causes hearing and visual loss in humans. Here we studied the regulation of HM7A. The actin-activated ATPase activity of full-length HM7A (HM7AFull) was lower than that of tail-truncated HM7A (HM7AΔTail). Deletion of the C-terminal 40 amino acids and mutation of the basic residues in this region (R2176A or K2179A) abolished the inhibition. Electron microscopy revealed that HM7AFull is a monomer in which the tail domain bends back toward the head-neck domain to form a compact structure. This compact structure is extended at high ionic strength or in the presence of Ca²⁺. Although myosin VIIA has five isoleucine-glutamine (IQ) motifs, the neck length seems to be shorter than the expected length of five bound calmodulins. Supporting this observation, the IQ domain bound only three calmodulins in Ca²⁺, and the first IQ motif failed to bind calmodulin in EGTA. These results suggest that the unique IQ domain of HM7A is important for the tail-neck interaction and, therefore, regulation. Cellular studies revealed that dimer formation of HM7A is critical for its translocation to filopodial tips and that the tail domain (HM7ATail) markedly reduced the filopodial tip localization of the HM7AΔTail dimer, suggesting that the tail-inhibition mechanism is operating in vivo. The translocation of the HM7AFull dimer was significantly less than that of the HM7AΔTail dimer, and R2176A/R2179A mutation rescued the filopodial tip translocation. These results suggest that HM7A can transport its cargo molecules, such as USH1 proteins, upon release of the tail-dependent inhibition.     

Subjective Estimation of the Trajectory Length of Fused Auditory Image Movement

The perceived trajectory length of the movement of a fused auditory image (FAI) against the background of interaural intensity differences was estimated in eight subjects upon dichotic stimulation through headphones. FAI movement was created by gradually changing the interaural delay (ΔT) between clicks in binaurally presented series of clicks from 0 to ±630 μs. When the FAI moved from the left to the right, an increase in interaural intensity difference (ΔI) from 0 to +13 dB (in the right channel of stimulation) significantly shortened the FAI trajectory because of a greater lateralization of the start point of FAI movement as compared to its end point. In the case of an oppositely directed movement (from the right to the left), the movement trajectory significantly decreased when ΔI increased from 0 to −13 dB (i.e., in the left stimulation channel), which was also explained by the greater lateralization of the start point of FAI movement as compared to its end point.__________Translated from Fiziologiya Cheloveka, Vol. 31, No. 3, 2005, pp. 32–38.Original Russian Text Copyright © 2005 by Varyagina.