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Biomedical subjects

L Green

Publications and source records attributed to L Green.

At least 325 records · Page 18Linked to original sources
PubMed1967

Energy needs versus environmental pollution: a reconciliation?

In this article I have presented, for discussion, a proposed system for energy generation by which the principal sources of environmental pollution by power plants could be eliminated. For stationary power plants the concept appears feasible technically and, according to my " horseback estimates," perhaps economically as well, depending upon the economic value of the by-products of sulfur, CO(2), water, and possibly nitrogen, and upon the price we are willing to pay for a clean environment .Thus, a more thorough engineering and economic analysis to explore these and other factors in greater depth seems warranted. In the case of turbine-driven vehicles, the technical and economic feasibility of widespread distribution and handling of the fuel constitutes a serious question, but one which deserves equally serious consideration before the possibility is discounted. The reports of the cited study panels notwithstanding, the technology required for the proposed system exists today, with one exception. This exception (which is not essential for trial of the system but will be required for its complete fruition) is the development of a nuclear reactor for the prime purpose of delivering process heat for the steam reforming of natural gas and, ultimately, for gas production from coal in a continuous process, such as those discussed by Pieroni et al. (16). Today's intermittent processes of coking and gas production are both archaic and themselves large sources of atmospheric pollution, and a development program aimed at advancing the technology of the coal industry in this regard would seem long overdue. The report of the PSAC Environmental Pollution Panel recommended "demonstration of the feasibility and economy of new developments for abating or controlling pollution through their use at Federal installations" and suggested the coalburning TVA power plants as a likely place for such demonstration. This suggestion is doubly appropriate since the TVA is in a region of subnormal " atmospheric ventilation" (8). By design these plants are adjacent to the AEC's Oak Ridge National Laboratory, and such a location would seem ideal for an experiment on the wedding of nuclear and fossil sources of energy. In comments on a preliminary draft of this article, proponents of "conventional " nuclear power pointed out that such power is hard to beat on the basis of cost, and that dissipation of heat to the air by way of cooling towers can also be accomplished in conventional plants (17). These observations are individually correct but not compatible: the low power costs cited are for very large plants [of the order of 1000 mega-watts lectrical) and larger], and the costs of cooling towers and associated equipment needed to dissipate such large amounts of heat [of the order of 2000 megawatts (thermal)] to air from a closed cycle would offset the power cost advantage of the large plant. In regard to the proposed use of nuclear process heat, Weinberg (20) has expressed doubt that much advantage can be derived from this approach because the temperatures involved are too high for low-cost reactors, and heat transfer from surfaces could involve materials problems. In the case of gas production, this is indeed an anticipated problem-not a technologically insuperable one, but a problem of reducing the cost of the materials required (16). Indeed, Weinberg himself has mentioned this possible use of nuclear heat in a recent publication discussing the steam reforming of coal to liquid fuel(21). Also, an improved process for synthesizing methane from lignitec has recently been reported (22). Since the earlier studies date back a decade, a new look at the problems and costs involved relative to the benefits to be derived (not the least of which could be new vigor for the coal industry) would seem to be in order. In the case of steam reforming of natural gas, the temperature level (about 1500 degrees F) is such that the technology is available today, and a process-heat-reactor design study could be initiated without awaiting further developments.

Air Pollution↗
PubMedDate not supplied

Fears and phobias in people with diabetes.

Phobic disorders are more common in people with diabetes than in the general population. The management of phobic disorders in patients with diabetes, particularly when associated with a fear of hypoglycaemia, is especially challenging and requires close collaboration between psychological medicine and diabetes teams. Difficulty in distinguishing symptoms of anxiety from those of hypoglycaemia, and the real dangers associated with hypoglycaemia, complicate the delivery of psychological interventions that are used routinely in the treatment of phobias. Avoidance of hypoglycaemia can lead to deterioration in diabetes control. This case report describes a man with Type 1 diabetes who developed agoraphobia with panic disorder, associated with fear of hypoglycaemia and deterioration in glycaemic control. The management of patients with diabetes and phobic disorders, with particular reference to those associated with fear of hypoglycaemia, is discussed.

Adult↗
PubMedDate not supplied

Are there two classes of classically-conditioned responses?

It is proposed that two response classes interact during classical conditioning: (1) a specific effect which directs responding towards or away from the CS, depending upon whether a positive or negative outcome is signaled, and (2) a general, emotional effect which interferes with responding. The interaction between these two response classes can account for the varied results obtained under CER and autoshaping procedures, and must be considered in any analysis which attempts to account for the complex nature of the conditioned response.

Animals↗
PubMedDate not supplied

CT of isolated elbow in evaluation of trauma: a modified technique.

Described is a modified technique to study the elbow joint in isolation. Modifications include use of a stretcher and a rigid cross-board across the scanning table and the stretcher. High resolution studies, with additional reconstruction images, were obtained.

Adult↗
PubMedDate not supplied

Outcome after laparoscopic fundoplication is not dependent on a structurally defective lower esophageal sphincter.

With the advent of laparoscopic surgery and the recognition that gastroesophageal reflux disease often requires lifelong medication, patients with normal resting sphincter characteristics are now being considered for surgery. The outcome of these patients after fundoplication is unknown and formed the basis of this study. The study population consisted of 123 patients undergoing laparoscopic Nissen fundoplication between 1992 and 1996. All patients had increased esophageal acid exposure on 24-hour esophageal pH monitoring. Patients were divided into those with a normal (n = 36) and those with a structurally defective (n = 87) lower esophageal sphincter (LES), based on LES resting pressure (normal >6 mm Hg), overall length (normal >2 cm), and abdominal length (normal >1 cm), and their outcomes were assessed. Each group was subsequently divided into patients presenting with a primary symptom that was "typical" (heartburn, regurgitation, or dysphagia) or "atypical" (gastric, respiratory, or chest pain) of gastro-esophageal reflux, and outcome was assessed. Median duration of follow-up was 18 months after surgery. Overall, laparoscopic fundoplication was successful in relieving symptoms of gastroesophageal reflux in 90% of patients. Patients with a typical primary symptom had an excellent outcome irrespective of the resting status of the LES (95% and 97%, respectively). Atypical primary symptoms were significantly more common in patients with a normal LES (29%) than in those with a structurally defective LES (10%; P <0.05), and these symptoms were less likely (50%) to be relieved by antireflux surgery. Laparoscopic antireflux surgery is highly successful and not dependent on the status of the resting LES in patients with increased esophageal acid exposure and primary symptoms "typical" of gastroesophageal reflux. Antireflux surgery should be applied cautiously in patients with atypical primary symptoms.

Adult↗
PubMedDate not supplied

Squamous cell carcinoma of the pancreas.

Squamous cell carcinoma of the pancreas is a controversial entity. Although some reports show that it is metastatic from another source, others demonstrate that it is a primary tumor. Between 1988 and 1997, fourteen cases of pancreatic squamous cell carcinoma were identified in the records of our pathology department. In seven instances the features were consistent with squamous cell carcinoma with no adenomatous component. The records of six of these patients were available for review and constitute the basis for this report. Five patients were diagnosed by means of percutaneous CT-guided fine-needle aspiration, whereas the sixth patient was diagnosed using a transduodenal core needle biopsy. At the time of diagnosis four patients had lung lesions, three patients had liver lesions, and two patients had lytic bone lesions. One patient had a 6 cm esophageal lesion. Surgical intervention had no impact on treatment or palliation in one of the patients. Chemotherapy and radiation therapy, alone or in combination, were ineffective in all patients. Median survival from the time of diagnosis was 2 months. We conclude that in cases of squamous cell carcinoma of the pancreas, every effort should be made to exclude adenomatous components histologically within the tumor and to exclude another primary source of squamous cell carcinoma. This will allow a better understanding of this entity and a refinement of therapy.

Adult↗