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Biomedical subjects

R G Baker

Publications and source records attributed to R G Baker.

At least 19 recordsLinked to original sources
PubMed1996

Dendritic morphology of projection neurons in the cat pretectum.

The distribution and dendritic morphology of neurons in the cat pretectal nuclear complex were analyzed with respect to their projection to the ipsilateral dorsal lateral geniculate nucleus (LGNd) and the ipsilateral inferior olive (IO). Single and double retrograde tracing techniques were combined with intracellular injections of either horseradish peroxidase into electrophysiologically identified pretectal neurons or Lucifer Yellow into retrogradely labeled somata. Pretectal cells afferent to the LGNd were located in the nucleus of the optic tract (NOT), adjacent dorsal terminal nucleus of the accessory optic system (DTN), and posterior pretectal nucleus (NPP). Cells projecting to the IO were also distributed throughout the NOT-DTN and dorsal part of the NPP. Separate tracer injections (fluorogold and horseradish peroxidase [HRP] or granular blue) into the LGNd and the IO showed considerable overlap of labeled neurons in the NOT and dorsal NPP. Double-labeled neurons, however, were not observed after double tracer injections into LGNd and IO. Partial topographical segregation of the two populations was observed along the dorsoventral axis because LGNd-projecting neurons exhibited maximum density ventral to that of IO neurons. Pretectal cells to the LGNd had cell body diameters between 16 and 48 microns. Somatic shapes varied between fusiform and multipolar with considerable overlap between these two morphological appearances. Neurons projecting to the IO exhibited similar cell body sizes and their morphology also varied from fusiform to multipolar. Quantitative analysis of dendritic field size and orientation, number and order of dendritic arborizations, and symmetry of the dendritic tree revealed no statistically significant difference between the two neuronal populations. Hence, neurons of the two populations cannot be unequivocally identified just from the dendritic morphology. By contrast, dendritic morphology was correlated with the topographical location of either cell type within the pretectal nuclei rather than projection. Thus, the morphological appearance of neurons located dorsally predominantly was fusiform while neurons located ventrally mostly were multipolar.

Animals↗
PubMed1986

A central venous temperature sensing lead.

Pacemaker rate responsiveness derived from changing central venous blood temperature requires the development of sensor leads that are stable and reliable. The relevant characteristics of one such design are described. Temperature response time, data acquisition time, temperature sensitivity, and long-term sensor shunt impedance have been studied both in vitro and in vivo. These parameters are analyzed with respect to the intrinsic temperature signal and to pacemaker implementation problems.

Blood↗
PubMed1986

Television and video technology in the education of deaf children.

This paper describes a survey into the use of television and related visual media in the education of hearing-impaired children in the UK. The main purpose of the survey was to furnish background information for the development of a low-cost video subtitling system for use in special schools and in units for hearing-impaired children in ordinary schools. An effective method of reducing cost is to base the system on equipment that schools and units already have. The survey indicates that domestic-type video recorders are becoming almost universal. Suitable microcomputers for running subtitling software are also widespread. Other results of the survey reveal: (i) widespread and fairly heavy usage of schools television programmes; (ii) the need for various visual aids and for considerable effort on the part of teachers in making the programmes accessible to hearing-impaired children; (iii) a significant demand for subtitling equipment; (iv) higher incidence of more sophisticated television equipment (video cameras, teletext receivers) and of human technical support in special schools than in hearing-impaired units.

Adolescent↗
PubMed1984

Bipolar versus unipolar issues in DDD pacing.

The relative merits of unipolar and bipolar systems are reviewed in the context of DDD pacing. In order to allow reliable atrial sensing in the presence of myopotentials and exogenous noise, bipolar atrial sensing is desirable. Bipolar ventricular sensing will reduce the incidence of myopotential sensing and may reduce susceptibility to cross-talk. Unipolar systems, however, generally offer better stimulation characteristics. Considerations have led to the development of a new DDD pacemaker with bipolar sensing and unipolar pacing characteristics. The bipolar-sense/unipolar-pace pulse generator is simple to implement based upon a unipolar design and retains the simplicity, convenience, and reliability inherent in that mode.

Cardiac Pacing, Artificial↗
PubMed1979

Management of primary bladder cancer by a multidisciplinary team.

Results of management of a closed series of primary bladder carcinoma over a 20-year period by a multidisciplinary team are presented. Patients were classified by the TNM method before treatment. These experiences indicate that stage and grade are relevant to prognosis and treatment. The TNM classification can be precise and practical when used diligently by a treatment team. Although no new methods of treatment are offered, the treatment now available may be utilized to better effect if programmed to allow care of the patients by a team, especially if the team explores the limits of radiation and surgery in their hands.

Adenocarcinoma↗
PubMed1975

Human volunteer and anthropomorphic dummy tests of driver air cushion system.

The dynamic impact tests at Southwest Research Institute for the first time exposed human volunteers to production-like driver air cushion system depolyments at impact levels equivalent to a 30 mph barrier crash (48 kph). No significant injury was produced. At no time was it necessary for the secondary restraint systems to be utilized and the entire program schedule was carried out as planned. All tests were conducted under the most safe and controlled conditions possible, and typify only what the air cushions might accomplish in direct, head-on impacts up to 30 mph (48 kph). In comparing the test results, the anthropomorphic dummies' response to impact was conservative compared to the human volunteers. These and other human volunteer tests were run to help understand what might be expected in real world driving conditions. To further understand the value of this new safety system, 1000 1973 Chevrolets were built and places in a high mileage fleet across the couhtry. They now have accumulated 41 millions miles of experience and have had 15 accidents of sufficient severity that the air cushion depolyed. This fleet was followed with 1974 vehicles with air cushions sold to the general public as an option. These cars, combined with the test fleet, have accumulated approximately 60 million miles and have a total of 25 depolyments with 34 occupants in the front seat. There has been one fatality in accidents involving these vehicles, a seven week old baby boy. The child was not restrained in any protective carrier. All other injuries have been classified AIS-1 except for three AIS-2. Facial injuries have been very minimal and there have been no known hearing impairments as a result of these accident situations. To date, the results have been encouraging but caution must be taken in their interpretation. The population of drivers is not to be considered normal. The 60 million miles may appear to be a large number, but only represents 25 minutes of driving time of the total U.S. car population in 1 year.

Accidents, Traffic↗