Biomedical subjects

J Sager

Publications and source records attributed to J Sager.

5 recordsLinked to original sources

PubMed1994

Object-oriented model-driven control.

A monitoring and control subsystem architecture has been developed that capitalizes on the use of model-driven monitoring and predictive control, knowledge-based data representation, and artificial reasoning in an operator support mode. We have developed an object-oriented model of a Controlled Ecological Life Support System (CELSS). The model, based on the NASA Kennedy Space Center CELSS breadboard data, tracks carbon, hydrogen, and oxygen, carbon dioxide, and water. It estimates and tracks resource-related parameters such as mass, energy, and manpower measurements such as growing area required for balance. We are developing an interface with the breadboard systems that is compatible with artificial reasoning. Initial work is being done on use of expert systems and user interface development. This paper presents our approach to defining universally applicable CELSS monitor and control issues, and implementing appropriate monitor and control capability for a particular instance: the KSC CELSS Breadboard Facility.

Animals↗

PubMed1993

Diversity in the Chlamydia trachomatis histone homologue Hc2.

Chlamydia trachomatis elementary bodies contain two developmentally expressed histone H1 homologues. An 18-kDa histone homologue, Hc1, is conserved among C. trachomatis serovars and C. psittaci. The other histone homologue, Hc2 (encoded by hctB), varies in size between C. trachomatis serovars but is present in reduced amounts or absent from C. psittaci. The variation in Hc2 size among C. trachomatis serovars was found to be due to internal deletions from a region of the hctB gene encoding lysine- and alanine-rich pentameric repeats.

Amino Acid Sequence↗

PubMed1993

Accuracy of quantum sensors measuring yield photon flux and photosynthetic photon flux.

Photosynthesis is fundamentally driven by photon flux rather than energy flux, but not all absorbed photons yield equal amounts of photosynthesis. Thus, two measures of photosynthetically active radiation have emerged: photosynthetic photon flux (PPF), which values all photons from 400 to 700 nm equally, and yield photon flux (YPF), which weights photons in the range from 360 to 760 nm according to plant photosynthetic response. We selected seven common radiation sources and measured YPF and PPF from each source with a spectroradiometer. We then compared these measurements with measurements from three quantum sensors designed to measure YPF, and from six quantum sensors designed to measure PPF. There were few differences among sensors within a group (usually <5%), but YPF values from sensors were consistently lower (3% to 20%) than YPF values calculated from spectroradiometric measurements. Quantum sensor measurements of PPF also were consistently lower than PPF values calculated from spectroradiometric measurements, but the differences were <7% for all sources, except red-light-emitting diodes. The sensors were most accurate for broad-band sources and least accurate for narrow-band sources. According to spectroradiometric measurements, YPF sensors were significantly less accurate (>9% difference) than PPF sensors under metal halide, high-pressure sodium, and low-pressure sodium lamps. Both sensor types were inaccurate (>18% error) under red-light-emitting diodes. Because both YPF and PPF sensors are imperfect integrators, and because spectroradiometers can measure photosynthetically active radiation much more accurately, researchers should consider developing calibration factors from spectroradiometric data for some specific radiation sources to improve the accuracy of integrating sensors.

Evaluation Studies as Topic↗

PubMed1988

Pericardial pseudotumor. Echocardiographic observation of juxtacardiac pulmonary collapse.

Despite its value in the diagnosis of pericardial disease, two-dimensional echocardiography also is known to produce confounding results. Ten patients had juxtacardiac masses simulating pericardial tumor implants on echocardiographic examination ("pericardial pseudotumor") caused by juxtacardiac pulmonary atelectasis or lobar collapse. The atelectatic nature of these masses was based on echocardiographic delineation of pericardial and pleural anatomy, combined with ancillary radiographic and CT studies. Drainage of pleural fluid also led to disappearance of the masses on echocardiographic examination, suggesting that the masses were an ultrasonic manifestation of pulmonary atelectasis resulting from surrounding compressive effusive fluid. Finally, clinical follow-up failed to show development of malignant disease in any patient. The possibility of pericardial pseudotumor should be considered when ultrasound studies show juxtacardiac masses within large collections of pleural fluid, especially in the clinical absence of malignant disease.

Adult↗

PubMed1986

Therapeutic goals: quality and quantity of life.

The elderly population is projected to increase from the present 11 per cent of the overall population to 20 per cent by the year 2020. The efforts of the medical community are directed toward extending the quantity of life. However, economic necessity and technologic advance in medicine will dictate the health care delivery to the elderly, as quality of life becomes a major factor in therapeutic decision making.

Adrenergic beta-Antagonists↗