The role of the sound of tapping for nonvisual judgment of gap crossability.

The author investigated the possibility that nonvisual locomotion with a cane depends on the sound of the cane tapping. Blindfolded participants were asked to judge whether a gap in front of them could be crossed by walking. An acoustic analysis suggested that sound could, in theory, distinguish the gaps. Blindfolded sighted participants in Experiments 1 and 2 judged crossability under conditions in which only the sound of tapping was available and in which the sound was minimized; the third and fourth experiments included experienced cane users. Both inexperienced observers and experienced cane users were unaffected by sound reduction and were less able to discriminate gaps when using sound only than when using reduced sound. A fifth experiment indicated that active-passive differences were not responsible for these effects. Results indicate that sound is not necessary or sufficient for judging nonvisible crossability with a probe. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

When room size matters: Acoustic influences on emotional responses to sounds.

When people hear a sound (a “sound object” or a “sound event”) the perceived auditory space around them might modulate their emotional responses to it. Spaces can affect both the acoustic properties of the sound event itself and may also impose boundaries to the actions one can take with respect to this event. Virtual acoustic rooms of different sizes were used in a subjective and psychophysiological experiment that evaluated the influence of the auditory space perception on emotional responses to various sound sources. Participants (N = 20) were exposed to acoustic spaces with sound source positions and room acoustic properties varying across the experimental conditions. The results suggest that, overall, small rooms were considered more pleasant, calmer, and safer than big rooms, although this effect of size seems to disappear when listening to threatening sound sources. Sounds heard behind the listeners tended to be more arousing, and elicited larger physiological changes than sources in front of the listeners. These effects were more pronounced for natural, compared to artificial, sound sources, as confirmed by subjective and physiological measures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of two indicators of perceived egocentric distance under full-cue and reduced-cue conditions.

It has not been established that walking without vision to previewed targets is indeed controlled by perceived distance. To this end, we compared walking and verbal report as distance indicators, looking for a tight covariation in responses that would indicate control by a common variable. Targets from 79–500 cm away were presented under dark and well-lit conditions. Both verbal reports and walking indicated overestimation of near targets and underestimation of far targets under dark viewing conditions. Moreover, the finding that verbally reported distance plotted essentially as a single-valued function of walked distance and vice versa is evidence that both indicators were responding to the same internal variable, ostensibly perceived distance. In addition, binocular parallax, absolute motion parallax, and angular elevation were evaluated as distance cues, and only angular elevation exerted a large influence on perceived distance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

When and how are spatial perceptions scaled?

This research was designed to test the predictions of 2 approaches to perception. By most traditional accounts, people are thought to derive general-purpose spatial perceptions that are scaled in arbitrary, unspecified units. In contrast, action-specific approaches propose that the angular information inherent in optic flow and ocular–motor adjustments is rescaled and transformed into units related to intended actions. A number of studies have shown, for example, that the apparent distance to targets is scaled by the effort required to walk the extent. Such studies can be accommodated by the traditional account by asserting that the experimental manipulations of walking effort influenced not perception itself, but rather postperceptual response processes. The current studies were designed to assess when and how action-specific influences on distance perception have their effects. The results supported the action-specific account. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A botanical compound, Padma 28, increases walking distance in stable intermittent claudication

Thirty-six patients with a median age of sixty-seven years and a median duration of intermittent claudication of five years were randomized to either active treatment with Padma 28 or placebo. The effect of treatment was quantified by measurements of systemic and peripheral systolic blood pressures and by measurements of the pain-free and the maximal walking distance on a treadmill. The ankle pressure index (ankle systolic pressure/arm systolic pressure) was calculated. The group randomized to active treatment received two tablets bid containing 340 mg of a dried herbal mixture composed according to an ancient lamaistic preparation (Padma 28). After active treatments, administered over a period of four months in a double-blinded, randomized design, the patients allocated to this group attained a significant increase in the pain-free walking distance from 52 m (20-106) to 86 m (24-164; P < 0.05) and in the maximal walking distance from 115 m (72-218) to 227 m (73- > 1,000; P < 0.05). The patient-group receiving placebo treatments did not show any significant changes in either the painfree or the maximal walking distance. The authors could not demonstrate any significant changes in the ankle pressure index either during active or during placebo treatment. In conclusion, this study has shown that treatment with Padma 28 over a period of four months significantly increased the walking distance in patients with stable, intermittent claudication of long duration.     

Effect of Arousal on Internal Clock Speed in Real Action and Mental Imagery.

The possible implication of an internal clock as a mechanism accounting for the temporal homology between actual and mental walking is studied. To observe this phenomenon, stressful sound stimuli were used to increase arousal, which is known to activate the internal clock. Seventeen participants performed three tasks: (1) a time production task, used as a reference task reflecting the internal clock speed; (2) an actual walking task; and (3) a mental walking task, all three in two sound conditions (no noise and noise). The results showed a significant effect of arousal on time in each task. The effect of noise, increasing the arousal level, was greater in time production and mental imagery tasks than in real action. In addition, the percentages of change between the two sound conditions for actual and mental walking time were not statistically different. These findings are further evidence of the existence of a timing process common to actual and mental walking. The data are consistent with the implication of an internal clock in both actual and mental walking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An analysis of cues to auditory depth perception in free space.

Physical acoustics reveals a number of stimulus correlates of sound source distance. Quantitative estimates of these stimulus correlates are compared with appropriate psychophysical thesholds. Such comparisons show that most of these stimulus correlates can, with various restrictions, provide distance information detectable by the ear(s). The stimulus correlates dealt with at greatest length are: intensity, frequency spectrum at near and far distances, binaural intensity ratio, and interaural phase (or time) differences. Problems relating to the use of some of these stimulus correlates as cues are discussed. Other possible distance cues are briefly mentioned. The possible use of much of the available physical information in making distance judgments has not yet been adequately evaluated in psychophysical studies. (48 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Management of intermittent claudication with pentoxifylline: meta-analysis of randomized controlled trials

OBJECTIVE: To evaluate the efficacy of pentoxifylline therapy in improving the walking capacity of patients with moderate intermittent claudication. DATA SOURCES: A search of MEDLINE for trials published between 1976 and 1994 inclusive, and a bibliographic review of all articles retrieved. STUDY SELECTION: Randomized, placebo-controlled, double-blind clinical trials were selected that evaluated the pain-free walking distance (the distanced walked on a treadmill before the onset of calf pain) and the absolute claudication distance (the maximum distance walked on a treadmill) among patients with moderate intermittent claudication. Twelve study groups in 11 trials were included in the analysis. DATA EXTRACTION: In addition to information regarding the trial design, patient characteristics, dosages and treatment periods, the means and standard deviations were collected for both the pain-free walking and absolute claudication distances. Trial quality was also assessed. DATA SYNTHESIS: Overall, there was a statistically significant improvement in the pain-free walking distance after pentoxifylline therapy (weighted mean difference 29.4 m [95% confidence interval (CI) 13.0 to 45.9 m]); this finding was based on a total sample of 612 patients (308 in the treatment groups and 304 in the control groups). A significant improvement was also noted in the absolute claudication distance (weighted mean difference 48.4 m [95% CI 18.3 to 78.6 m]); this was based on a total sample of 511 patients (258 in the treatment group and 253 in the control group). In a sensitivity analysis of the pain-free walking distance, significant treatment effects and no statistically significant heterogeneity were found when only trials were included that were "medically eligible" (involved patients with stage II disease and a pain-free walking distance of 50 to 200 m). In a similar sensitivity analysis of the absolute claudication distance, the two conditions resulting in a significant treatment effect and no significant heterogeneity were the inclusion of "medically eligible" trials and those with a shorter treatment duration (13 weeks or less). CONCLUSION: Pentoxifylline therapy may be efficacious in improving the walking capacity of patients with moderate intermittent claudication. However, properly conducted clinical trials are required to provide a true estimate of the benefit.     

Tufted capuchin monkeys (Cebus apella) spontaneously use visual but not acoustic information to find hidden food items.

Foraging choices in tufted capuchins monkeys are guided by perceptual, cognitive, and motivational factors, but little is known about how these factors might interact. The present study investigates how different types of sensory information affect capuchins' ability to locate hidden food. In two experiments, capuchins were presented with two cups, one baited and one empty. Monkeys were given visual, acoustic, or acoustic-visual information related to the baited cup, the empty cup, or both baited and empty cup. Results show that capuchins spontaneously used visual information to locate food, and that information indicating presence and absence of food led to higher success rates than information indicating only absence of food. In contrast, acoustic information did not lead to success rates above chance levels and failed to enhance performance in combination with visual information. Capuchins spontaneously avoided a visually empty cup, but they did not appear to associate sounds with either the presence or absence of food. Being able to locate food items with the aid of acoustic cues might be a learned process that requires interactive experiences with the task's contingencies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Coupling of head and body movement with motion of the audible environment.

The authors asked whether standing posture could be controlled relative to audible oscillation of the environment. Blindfolded sighted adults were exposed to acoustic flow in a moving room, and were asked to move so as to maintain a constant distance between their head and the room. Acoustic flow had direct (source) and indirect (reflected) components. Participants exhibited strong coupling of postural motion with room motion, even when direct information about room motion was masked and was available only in reflected sound. Patterns of hip–ankle coordination closely resembled patterns observed in previous research involving coupling of sway with a visible moving room. The results demonstrate that blindfolded adults can control the dynamics of stance relative to motion of the audible environment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive load of navigating without vision when guided by virtual sound versus spatial language.

A vibrotactile N-back task was used to generate cognitive load while participants were guided along virtual paths without vision. As participants stepped in place, they moved along a virtual path of linear segments. Information was provided en route about the direction of the next turning point, by spatial language ("left," "right," or "straight") or virtual sound (i.e., the perceived azimuth of the sound indicated the target direction). The authors hypothesized that virtual sound, being processed at direct perceptual levels, would have lower load than even simple language commands, which require cognitive mediation. As predicted, whereas the guidance modes did not differ significantly in the no-load condition, participants showed shorter distance traveled and less time to complete a path when performing the N-back task while navigating with virtual sound as guidance. Virtual sound also produced better N-back performance than spatial language. By indicating the superiority of virtual sound for guidance when cognitive load is present, as is characteristic of everyday navigation, these results have implications for guidance systems for the visually impaired and others. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Quantitative analysis of human walking trajectory on a circular path in darkness

Thirteen normal (eight young and five older) subjects and a patient who was removed left sided acoustic neurinoma were tested to walk blindfolded along circular paths. They were asked to walk completing two revolutions and to stop when they judged they had returned to the initial position with their head faced to the initial directions. Movements of two markers on the subjects head were recorded by three dimensional motion analyzing system (ELITE system) at 50 Hz which allowed us to measure (a) total walked distance, (b) average radius of the trajectory, and (c) cumulative angle of rotation. Eight young subjects were tested on three circles with radii 0.5, 0.9, and 1.15 m, in two conditions (control, and with mental arythmetic), only to clockwise direction. Five older subjects and a patient were tested on a circle of 0.9 m radius in two conditions, but to both directions, counterclockwise and clockwise. Walked trajectories of young subjects were smooth, whereas those of older subjects tended to be polygonal. Young subjects overshot the ideal distance (6.6%) and ideal radius (9.5%), whereas they undershot the ideal angle (5.1%). There was no effect of circle size or condition on these variables. On the other hand, there was a significant effect of condition on average radius in the older group. The performance of older subjects seemed to be affected by the concurrent mental task. Comparing the counterclockwise walk, the older subjects undershot the turning angle much more than the young subjects which suggest deficits in the vestibular function with aging. The patient showed larger radius and smaller angle while she turned to the healthy side (clockwise) than to the affected side (counterclockwise). Lack of unilateral vestibular information seemed to have affected the circular walking trajectory.     

Cleavage of rat prolactin occurs within rat mammary tissue, and the cleaved form is present in serum but not in milk

A biofeedback gait training system for step length is proposed, adapted to the correction of spatial walking asymmetries by means of a simple, quick and reliable method for daily clinical use. The system is composed of a walkway and a gait analysis device (locometer) measuring the main temporal and distance factors of gait. The step length is imposed on the subject by lighted targets appearing on the walkway, alternately on the right and left side; the subject is asked to place a swinging foot on the lighted target. Feedback to the subject is supplied by direct visual information (the subject looking at the movement and the position of the foot with respect to the lighted target) and an acoustic signal delivered in real time when the length step error is greater than an allowed value. The method is validated on a population of hemiparetic patients who have suffered from a stroke and who have been reeducated with traditional rehabilitation methods. The patients were divided into two groups; one group following a gait training with biofeedback (BFB group) and one group following a gait training without biofeedback (reference group). Preliminary results are presented, showing a significant beneficial effect of the biofeedback method in increasing the step length of paretic limbs and in correcting step-length asymmetry.     

Is intermittent claudication improved by percutaneous transluminal angioplasty? A randomized controlled trial

PURPOSE: Percutaneous transluminal angioplasty (PTA) is an increasingly popular invasive treatment for peripheral arterial disease, but there have been very few controlled trials to justify its use. This randomized controlled clinical trial was performed to determine in patients with mild and moderate intermittent claudication differences in outcome between PTA and conventional medical treatment after 2 years. METHODS: Six hundred patients with claudication were screened at the Peripheral Vascular Clinic, Royal Infirmary of Edinburgh. Sixty-two patients with short femoral artery stenoses or occlusions (47 patients) and iliac stenoses (15 patients) were randomized to either PTA plus medical treatment (PTA group, 30 patients) or to medical treatment alone (control group, 32 patients). Medical treatment consisted of daily low-dose aspirin and advice on smoking and exercise. Outcome measures studied were patient-reported maximum walking distance, exercise treadmill distance until onset of claudication, treadmill maximum walking distance, ankle-brachial pressure index (ABPI), quality of life (Nottingham Health Profile), and duplex ultrasound-measured extent of occlusive disease. RESULTS: At 2 years of follow-up, the PTA group and control subjects did not differ significantly in patient-reported maximum walking, treadmill onset to claudication, treadmill maximum walking distances, or ABPI (p > 0.05). However, the PTA group had significantly fewer occluded arteries (p = 0.003) and a lesser degree of stenosis (expressed in terms of the velocity ratio; p = 0.004) in patent arteries. Quality of life was not demonstrably different between the two groups (p > 0.05). CONCLUSIONS: Two years after PTA, patients had less extensive disease than medically treated patients, but this did not translate into a significant advantage in terms of improved walking or quality of life. There are important implications for patient management and future clinical research.     

Production and characterisation of monoclonal antibodies specific for bovine interleukin-4

This study assessed physical activity patterns in a sample of urban African Americans, whose participation in physical activity has not previously been well-described. From questions administered by interviewers during health fair screenings in 19 churches in East Baltimore, information regarding participation in regular, leisure-time activity (defined as 30 minutes of activity, 5 days per week), time spent walking on the job, and distance walked to and from work was assessed from 365 adults (69% women). Regular, leisure-time activity participation was 18% for men and 16% for women. When the definition of physical activity participation was broadened to include: (1) spending over half the day walking at work; (2) walking at least 10 blocks to and from work; as well as (3) regular, leisure-time activity, 41% of men and 38% of women were active. These data suggest that, while a small percentage of African Americans participate in regular physical activity, a substantial percentage are regularly active when non-leisure-time activity is assessed. To accurately characterize overall participation, physical activity derived from a variety of sources, including transportation and work-related activity, should be assessed.     

Behavioral studies of sound localization in the cat

Using the magnetic search coil technique to measure eye and ear movements, we trained cats by operant conditioning to look in the direction of light and sound sources with their heads fixed. Cats were able to localize noise bursts, single clicks, or click trains presented from sources located on the horizontal and vertical meridians within their oculomotor range. Saccades to auditory targets were less accurate and more variable than saccades to visual targets at the same spatial positions. Localization accuracy of single clicks was diminished compared with the long-duration stimuli presented from the same sources. Control experiments with novel auditory targets, never associated with visual targets, demonstrated that the cats localized the sound sources using acoustic cues and not from memory. The role of spectral features imposed by the pinna for vertical sound localization was shown by the breakdown in localization of narrow-band (one-sixth of an octave) noise bursts presented from sources along the midsagittal plane. In addition, we show that cats experience summing localization, an illusion associated with the precedence effect. Pairs of clicks presented from speakers at (+/-18 degrees,0 degrees ) with interclick delays of +/-300 microsec were perceived by the cat as originating from phantom sources extending from the midline to approximately +/-10 degrees.     

Haptic perception of the distance walked when blindfolded.

The ability to detect the distance walked when blindfolded using only haptic information generated by the walking activity was investigated. Participants walked a straight path until told to stop, turned, and attempted to return to their starting point. The path was completely featureless. Counting was prevented. Blindfolded, sighted participants traveled with a long cane or a trained sighted guide. Gait was varied or distorted In all experiments the return distance was a linear function of the set distance, with some participants giving and some conditions resulting in remarkably sensitive performances. The magnitude of errors was a linear function of step length. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ultrasonic nondestructive evaluation of matrix structures and nodularity in cast irons

The primary purpose of this research was to investigate the nondestructive ultrasonic wave response, in terms of acoustic velocities and attenuation of sound energy, in cast irons with different nodularities and matrix structures and its correlation with mechanical properties. The results indicated that the influences of matrix structures on the acoustic velocities were not apparent in the cast irons investigated. As to the nodularity, when graphites were largely spheroidal in shape (i. e., nodularity over 80 pct), the velocity of longitudinal waves propagation was about 5300 to 5500 m/s. The velocities seemed to decrease linearly down to nodularity of 25 pct, where velocity was approximately 4800 m/s. Below 25 pct nodularity, the values of acoustic velocity dropped rapidly to about 4000 to 4200 m/s. This represented the velocity of longitudinal waves propagation in gray cast iron, in which the graphites appeared in flake form. The analysis of the attenuation of ultrasonic amplitude indicated that when the nodularity of cast irons is low, the echo sound amplitude will decay more rapidly with respect to distance of echo sound travel. As to the matrix structures, ferritic, bainitic, ferritic-pearlitic (low pearlite content) and tempered martensitic matrix structures were found to have similar ultrasonic attenuation characteristics at the testing frequency of 2 MHz. A higher amount of pearlite (over 90 pct) or fresh martensite in the matrix of cast irons has resulted in faster attenuation of ultrasonic energy, with the fresh martensitic matrix being the fastest. At a testing frequency of 4 MHz, the attenuation of the ultrasonic amplitude in pearlitic and fresh martensitic matrices was found to be even greater than that of 2 MHz. However, other matrices exhibited similar attenuation behavior at both 2 and 4 MHz frequencies. The relationship between the mechanical properties of various cast irons and ultrasonic characteristics was also examined. JIA-MING SUEN, formerly Graduate Student, Department of Materials Engineering, Tatung Institute of Technology     

Neural computations for sound pattern recognition: evidence for summation of an array of frequency filters in an echolocating bat

Microchiropteran bats use an auditory sonar system for orientation and prey capture. Many bats use highly structured constant-frequency (CF) and frequency-modulated (FM) sonar orientation signals. Mechanisms for sound pattern recognition are important for the perception of these and other types of auditory signals. The processing and recognition of FM sound components appears to be important for certain complex perceptual tasks, including target distance perception. I have conducted behavioral studies using artificial echoes to simulate the conditions of a bat flying toward a target. An innate vocalization response of the bat to the simulated approaching target was used to assess the ability of the bat to analyze the structure of and extract distance information from different types of synthetic FM sound patterns. The bat's performance depended on the structure of the artificial echo. The pattern recognition performance of the bats was similar when they were presented with either a naturally structured artificial CF/FM echo or an artificial CF/FM echo containing an FM component consisting of a series of pure tone steps. The ability of the bats to recognize appropriately the structure of an FM signal constructed from a sequence of pure tones depended on the number of pure tone steps in the series. Noctilio was able to recognize FM sound patterns containing 99 or greater pure tone steps. The minimum required number of pure tone steps could be distributed over different frequency ranges. The bats were able to resolve individual tone steps in the series that were separated by at least 100 Hz.(ABSTRACT TRUNCATED AT 250 WORDS)