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K J Kurtz

Publications and source records attributed to K J Kurtz.

11 recordsLinked to original sources
PubMed1992

The role of central and peripheral vision in perceiving the direction of self-motion.

Three experiments were performed to examine the role that central and peripheral vision play in the perception of the direction of translational self-motion, or heading, from optical flow. When the focus of radial outflow was in central vision, heading accuracy was slightly higher with central circular displays (10 degrees-25 degrees diameter) than with peripheral annular displays (40 degrees diameter), indicating that central vision is somewhat more sensitive to this information. Performance dropped rapidly as the eccentricity of the focus of outflow increased, indicating that the periphery does not accurately extract radial flow patterns. Together with recent research on vection and postural adjustments, these results contradict the peripheral dominance hypothesis that peripheral vision is specialized for perception of self-motion. We propose a functional sensitivity hypothesis--that self-motion is perceived on the basis of optical information rather than the retinal locus of stimulation, but that central and peripheral vision are differentially sensitive to the information characteristic of each retinal region.

Adult↗
PubMed1991

On the sufficiency of the velocity field for perception of heading.

All models of self-motion from optical flow assume the instantaneous velocity field as input. We tested this assumption for human observers using random-dot displays that simulated translational and circular paths of movement by manipulating the lifetime and displacement of individual dots. For translational movement, observers were equally accurate in judging direction of heading from a "velocity field" with a two-frame dot life and a "direction field" in which the magnitudes of displacement were randomized while the radial pattern of directions was preserved, but at chance with a "speed field" in which the directions were randomized, preserving only magnitude. Accuracy declined with increasing noise in vector directions, but remained below 2.6 degrees with a 90 degrees noise envelope. Thus, the visual system uses the radial morphology of vector directions to determine translational heading and can tolerate large amounts of noise in this pattern. For circular movement, observers were equally accurate with a 2-frame "velocity field", 3-frame "acceleration" displays, and 2-frame and 3-frame "direction fields", consistent with the use of the pattern of vector directions to locate the center of rotation. The results indicate that successive independent velocity fields are sufficient for perception of translational and circular heading.

Humans↗
PubMed1985

Serum creatine kinase BB isoenzyme as a diagnostic aid in occult small cell lung cancer.

Four patients with metastatic small cell carcinoma of the lung who had initial chest x-rays that did not reveal the cancer showed striking elevations of serum creatine kinase BB isoenzyme, which suggested the diagnosis and directed the subsequent evaluation. Creatine kinase BB isoenzyme elevation with widespread small cell carcinoma of the lung is probably more common than currently recognized, and is a useful diagnostic indicator for extensive stage small cell lung cancer, even in the absence of central nervous system metastases.

Aged↗
PubMed1985

Severe exposure hypothermia: a resuscitation protocol.

Although hypothermia has been described as an emergency in suspended animation, severe degrees of hypothermia mandate appropriate aggressive intervention. Because of cardiac instability with core temperature below 28 C, aggressive invasive rewarming by F-F partial bypass is often ideal in this setting. In contrast, a gentle approach in other therapeutic maneuvers is equally important to prevent iatrogenic induction of VF in nonarrested victims. If the only definite criterion for diagnosis of death in hypothermia is failure to respond to resuscitation and rewarming, successful resuscitation must carefully balance aggressive and gentle interventions. Because CPR protocols involve legal as well as medical questions, additional prospective data are especially critical for resolving controversies in the initial management of profound exposure hypothermia.

Arrhythmias, Cardiac↗
PubMed1985

Medical recommendations for wilderness travel. 3. Medical supplies and drug regimens.

Even if the wilderness traveler is fit and up-to-date on management of the many illnesses and injuries that may occur on an outing, proper care cannot be given unless the appropriate supplies are available. Thus, the contents of a medical travel kit should be carefully chosen, using the type of trip, duration of travel, and distance from medical care as criteria.

Anti-Bacterial Agents↗
PubMed1984

Dynamic vascular auscultation.

Dynamic auscultation, defined as physiologic or pharmacologic maneuvers that alter cardiovascular sounds in predictable ways, is increasingly practiced in cardiac physical diagnosis. Dynamic maneuvers applicable to peripheral arterial sounds have also been described and deserve wider application since arterial occlusive disease is encountered frequently. These little-known maneuvers alter blood flow into and away from a critical stenosis, as well as flow through side branch arteries, thus allowing the examiner to accentuate and localize arterial bruits by modifying their intensity and duration. In this review, the pathophysiology of bruit production is applied to a description of specific bruit manipulations useful in the neck, chest, abdomen, and extremities. Application of these dynamic maneuvers during vascular auscultation should allow more discriminating use of subsequent expensive or invasive diagnostic procedures.

Abdomen↗
PubMed1982

Training the internist for primary care: a view from Nevada.

The recent establishment of primary care residencies at the University of Nevada School of Medicine has raised important questions about local priorities in the training of physicians to provide primary care for adults. Because the amount of money available for health care training is decreasing, these questions also have national importance. Primary care internal medicine, not synonymous with general internal medicine, offers distinct advantages to patients over family practice adult care and primary care offered by internist subspecialists. The University of Nevada has a singular opportunity to organize a strong primary care internal medicine residency, but national problems of internal medicine emphasis exist. Nationwide changes in internal medicine residency programs (ongoing) and American Board of Internal Medicine nationalization of the fledgling primary care internal medicine fellowship movement are suggested. Specifically proposed is an extra year for primary care training with a single examination after four years, producing general internists with a primary care "minor." Alternately, and ideally, there would be a full two-year primary care fellowship with a separate internal medicine primary care subspecialty board examination. Either of the above options would provide necessary training and academic credibility for primary care internists, and would redirect internal medicine certification and training.

Fellowships and Scholarships↗