Biomedical subjects

Andrea Bubka

Publications and source records attributed to Andrea Bubka.

6 recordsLinked to original sources

PubMed2006

Chromaticity, spatial complexity, and self-motion perception.

The effects of visual field color and spatial complexity on self-motion perception were investigated by placing observers inside a large rotating cylinder (optokinetic drum). Under optokinetic-drum conditions visually induced self-motion (vection) is typically perceived within 30 s, even though all forms of sensory input (eg vestibular, proprioceptive, auditory), except vision, indicate that the observer is stationary. It was hypothesized that vection would be hastened and vection magnitude increased by adding chromatic colors and spatial complexity to the lining of an optokinetic drum. Addition of these visual-field characteristics results in an array that shares more visual-field characteristics with our typical environment that usually serves as a stable frame of reference regarding self-motion perception. In the color experiment, participants viewed vertical stripes that were: (i) black and white, (ii) various gray shades, or (iii) chromatic. In the spatial complexity experiment, participants were presented with: (i) black-and-white vertical stripes, or (ii) a black-and-white checkerboard pattern. Drum rotation velocity was 5 rev. min(-1) (30 degrees s(-1)), and both vection onset and magnitude were measured for 60 s trials. Results indicate that chromaticity and spatial complexity hasten the onset of vection and increase its perceived magnitude. Chromaticity and spatial complexity are common characteristics of the environments in which our visual system evolved. The presence of these visual-field features in an optic flow pattern may be treated as an indicator that the scene being viewed is stationary and that the observer is moving.

Adult↗

PubMed2006

Rotation velocity change and motion sickness in an optokinetic drum.

BACKGROUND: Stationary subjects who view the interior of an optokinetic drum often experience motion sickness (MS) symptoms, perhaps because visual and vestibular sensory inputs are in conflict. It was predicted that intermittently changing drum rotation velocity would cause an increase in sensory conflict, and subsequently lead to more MS. Visual input indicating frequent changes in self-motion would not be consistent with vestibular input indicating no self-motion. When drum rotation is steady, visual and vestibular inputs are more likely to agree given that the vestibular organs only respond to change. METHODS: There were 12 individuals who participated in the experiment (7 men, 5 women, mean age = 24.0 yr). In two conditions subjects viewed the interior of an optokinetic drum that steadily rotated at either 5 RPM or 10 RPM. In a third condition drum velocity alternated every 30 s between 5 RPM and 10 RPM (5/10 RPM condition). In all conditions the subject's head was immobilized in the center of the drum that rotated on an Earth-vertical axis. Subjects completed the Simulator Sickness Questionnaire (SSQ) designed by Kennedy and colleagues both before a trial and after 4 min of drum viewing. A total SSQ score and three SSQ sub-scores (nausea, oculomotor, and disorientation) were obtained. RESULTS: Mean post-treatment total SSQ scores (mean = 41) were significantly the highest in the 5/10 RPM condition followed by the conditions of steady rotation velocity at 10 RPM (mean = 36) and 5 RPM (mean = 24). Likewise, mean nausea sub-scores were also the highest (mean = 24) in the 5/10 RPM condition followed by the 10 RPM condition (mean = 19) and the 5 RPM condition (mean = 11). CONCLUSIONS: These results support the hypothesis that a conflict between sensed and expected effects of self-motion alone can lead to MS. Changing rotation velocity increases sensory conflict that in turn leads to more MS.

Adult↗

PubMed2005

Rotation direction change hastens motion sickness onset in an optokinetic drum.

BACKGROUND: Many stationary subjects who view the patterned interior of a rotating cylinder (optokinetic drum) experience motion sickness (MS) symptoms. An experiment was conducted to investigate the effects of rotation direction change on MS onset and severity. It was predicted that intermittently changing rotation direction would hasten MS onset due to an increased degree of visual/vestibular sensory conflict. METHODS: There were 12 individuals who participated in the experiment (4 men, 8 women, mean age = 24.4 yr). Subjects viewed the interior of an optokinetic drum that rotated at 5 rpm (30 degrees x s(-1)). Drum rotation was either consistently in the same direction or rotation direction changed every 30 s. Eight MS symptoms were assessed at 2-min intervals using a subjective scale (0 = none, 1 = slight, 2 = moderate, 3 = severe). RESULTS: Overall, MS onset was fastest when drum rotation direction changed. Specific MS symptoms significantly affected were dizziness, stomach awareness, and nausea. CONCLUSIONS: These results suggest that a lack of correlation between the sensed and expected effects of motion alone can lead to MS. These results cannot be accounted for by a lack of correlation between sensed and expected gravitational vertical given that these were held constant across conditions.

Adult↗

PubMed2004

Infertility practice management. I. Leadership and management style: results from the 2002 survey of 374 Society for Assisted Reproductive Technology member centers.

OBJECTIVES: To identify current trends in management and leadership styles in Society for Assisted Reproductive Technology (SART) member infertility centers; and to understand the similarities and disparities that exist in physicians', administrators', and staff perceptions of management and leadership styles in these centers. MATERIALS AND METHODS: Questionnaires were developed to collect information on the leadership and management styles in place in SART member infertility centers. Survey instruments were distributed to the 374 SART centers. Survey instruments for one physician, the center administrator, and six staff members (two each in nursing, laboratory, and administration) were issued to the SART liaison in each of the SART member centers. Respondents included physicians, practice administrators, nurses, technicians, patient services, billing, and support staff. RESULTS AND DISCUSSION: Analysis of respondents' answers revealed that surveyed staff members reported a fairly high degree of job satisfaction. Physician and administrator management styles seemed to fall between interactive and directive styles; however, physicians and administrators perceived themselves as being more interactive than other staff members viewed them. Overall, extreme differences were unlikely, given the reported high degree of job satisfaction. Finally, survey outcome data were compared with responding centers' ART outcome rates as published by the Centers for Disease Control and Prevention (CDC). CONCLUSIONS: Overall, although employee job satisfaction seemed to be high, there were statistical differences between groups for several questions; the disparities in responses for these questions are indicators for potential management and leadership consideration. In addition, statistical correlations were found between the responses for several questions and the centers' respective CDC-published ART outcome rates.

Adult↗

PubMed2004

Display color affects motion sickness symptoms in an optokinetic drum.

BACKGROUND: Many stationary participants who view the patterned interior of a rotating cylinder (optokinetic drum) experience motion sickness (MS) symptoms. Most drum interiors have consisted of black and white patterns. An experiment was conducted to investigate the effects of chromaticity on MS onset and severity. METHODS: There were 12 individuals who participated in the experiment (4 men, 8 women, mean age = 25). Keeping rotation speed constant (5 RPM), the color of vertical stripes in an optokinetic drum was manipulated. There were three conditions used: 1) alternating black and white stripes; 2) gray stripes having different luminance values; and 3) chromatic stripes (white, red, yellow, black, green, and blue) that approximately matched the luminance values of the stripes in the gray condition. Every 2 min, eight motion sickness symptoms were assessed (for up to 16 min) using a subjective scale (0 = none, 1 = slight, 2 = moderate, 3 = severe). RESULTS: Overall, MS onset was fastest, and symptoms the most severe, in the chromatic condition. The two major MS symptoms that were significantly affected were headache and dizziness. CONCLUSIONS: Chromaticity may affect how much an observer's visual environment appears to be stationary, perhaps because chromaticity is such a common feature of the stationary environment in which our visual system evolved. In an optokinetic drum, the addition of chromaticity may increase the disparity between visual and vestibular inputs, a factor thought by many to contribute to MS onset and severity.

Adult↗

PubMed2003

Optokinetic drum tilt hastens the onset of vection-induced motion sickness.

BACKGROUND: Under optokinetic drum conditions, a stationary participant views the patterned interior of a rotating drum. Quickly, most participants perceive illusory self-rotation in the direction opposite to the drum's true rotation (vection). It has been documented that up to 60% of participants experience motion sickness-like symptoms under optokinetic conditions perhaps because of conflicting sensory information from the visual and vestibular systems. METHODS: Keeping rotation speed constant (10 RPM), drum tilt relative to the axis of rotation was systematically manipulated (0 degrees, 5 degrees, 10 degrees), producing a wobble effect. Overall well-being and eight motion sickness symptoms were assessed every 2 min using subjective scales. RESULTS: Participants reported 1) a complex type of circular vection that included a "wobble" or "sway" component and 2) a quicker onset of motion sickness-like symptoms as tilt increased. CONCLUSION: In a tilted drum, the vestibular system correctly indicates that the participant is stationary while the visual system indicates a complex type of self-rotation. This type of sensory conflict is more severe than what takes place under typical optokinetic drum conditions (no tilt). Results suggest that as visual/vestibular sensory conflict increases, so does the speed at which motion sickness symptoms occur.

Humans↗