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Biomedical subjects

J D Allan

Publications and source records attributed to J D Allan.

59 records · Page 4Linked to original sources

Chemical and microphysical characterization of ambient aerosols with the aerodyne aerosol mass spectrometer.

The application of mass spectrometric techniques to the real-time measurement and characterization of aerosols represents a significant advance in the field of atmospheric science. This review focuses on the aerosol mass spectrometer (AMS), an instrument designed and developed at Aerodyne Research, Inc. (ARI) that is the most widely used thermal vaporization AMS. The AMS uses aerodynamic lens inlet technology together with thermal vaporization and electron-impact mass spectrometry to measure the real-time non-refractory (NR) chemical speciation and mass loading as a function of particle size of fine aerosol particles with aerodynamic diameters between approximately 50 and 1,000 nm. The original AMS utilizes a quadrupole mass spectrometer (Q) with electron impact (EI) ionization and produces ensemble average data of particle properties. Later versions employ time-of-flight (ToF) mass spectrometers and can produce full mass spectral data for single particles. This manuscript presents a detailed discussion of the strengths and limitations of the AMS measurement approach and reviews how the measurements are used to characterize particle properties. Results from selected laboratory experiments and field measurement campaigns are also presented to highlight the different applications of this instrument. Recent instrumental developments, such as the incorporation of softer ionization techniques (vacuum ultraviolet (VUV) photo-ionization, Li+ ion, and electron attachment) and high-resolution ToF mass spectrometers, that yield more detailed information about the organic aerosol component are also described.

Journal Article↗

Self in relation: a prolegomenon for holistic nursing.

We have outlined some of the characteristics of holistic nursing and have named and explored the concepts that we believe are important to holistic practice. We have outlined assumptions that offer to nursing a more caring and connected way of interacting with clients than currently exists in nursing practice. We do not have answers to the questions of how to implement this practice within the structure of current nursing practice. Occasionally when we discuss these ideas with other nurses, they tell us that nursing as currently practiced in hospitals and community agencies is just the "real world," as though we had better get used to it. Maybe the world that we have presented is the "unreal world," for the moment at least. We are proud to live and learn in this unreal world and in a community of folks who make their living in holistic practice. If we had to make our living working in the "real world" of health care, could we do something to change it before the conflicts drove us away? The concluding question is, "Will nurses use their joint power to build therapeutic environments within nursing, or must they defect from nursing to practice holistic care?"

Acquired Immunodeficiency Syndrome↗

To lose, to maintain, to ignore: weight management among women.

The purpose of this study was to describe the process of weight management and the factors that influence this process in a sample of 37 middle-class and working-class white women of varied body size. A naturalistic study design, with a cultural-ecological theoretical orientation and ethnographic interviewing techniques, was used. The findings indicated that there were five stages through which women moved, repeatedly, as they managed weight: appraising, deemphasizing, mobilizing, enacting, and maintaining. Each stage consisted of multiple processes characterized by the use of personally developed tactics and strategies. Concern about appearance rather than health was a more salient factor in the initiation of weight-loss efforts. Progression through the five-stage pathway for weight management was influenced by time and informants' weight. Implications for practice include helping clients reduce the difficulty of altering cultural routines of eating and exercise and eliciting clients' own norms for body size.

Adaptation, Psychological↗

Management of infections caused by gram-negative bacilli: the role of antimicrobial combinations.

Treatment with antimicrobial combinations is generally used to provide broad-spectrum coverage and/or to enhance antimicrobial activity (synergism). Extensive in vitro documentation of synergism exists for many such combinations, but an obvious benefit has been difficult to demonstrate clinically. Several types of therapeutically useful combinations often result in synergism; these combinations include a cell wall-active agent with an aminoglycosidic aminocyclitol, a beta-lactamase inhibitor with a beta-lactam antibiotic, and agents that inhibit sequential steps in a metabolic pathway. Combinations of beta-lactam antibiotics may be synergistic by means of several mechanisms, but such combinations have significant potential for antagonism when used against gram-negative bacilli and, thus, must be evaluated closely before clinical use.

Aminoglycosides↗