High-temperature slow crack growth of silicon carbide determined by constant-stress-rate and constant-stress testing

High-temperature slow-crack-growth behaviour of hot-pressed silicon carbide was determined using both constant-stress-rate (dynamic fatigue) and constant-stress (static fatigue) testing in flexure at 1300 °C in air. Slow crack growth was found to be a governing mechanism associated with failure of the material. Four estimation methods such as the individual data, the Weibull median, the arithmetic mean and the median deviation methods were used to determine the slow crack growth parameters. The four estimation methods were in good agreement for the constant-stress-rate testing with a small variation in the slow-crack-growth parameter, n, ranging from 28 to 36. By contrast, the variation in n between the four estimation methods was significant in the constant-stress testing with a somewhat wide range of n=16 to 32. © 1998 Chapman & Hall     

Lost in menuspace: user interactions with complex medical devices

The advent of fast-acting drugs has made the infusion pump the most pervasive electronic medical device in the acute care (hospital) environment. Despite the importance of its correct operation, incident reports in the US Food and Drug Administration (FDA) database implicate interface programming as a significant aspect of adverse outcomes. This article describes a study of infusion pump-programming performance by experienced healthcare professionals in a major urban teaching hospital. Early findings indicate that practitioner experience with device programming does not increase proficiency. This suggests that a complex menu structure ("menuspace") makes programming difficult and inefficient in ways that impede practitioner development of mental models that are sufficient for reliable device operation. This causes operators to become disoriented in the interface structure, or "lost in menuspace." We relate these findings to the current study of the USFDA adverse events reports and indicate directions for further research.     

Rubber particle agglomeration phenomena in acrylonitrile-butadiene-styrene (ABS) polymers. I. Structure-property relationships study on rubber particle agglomeration and molded surface appearance

The effects of molecular structures of ABS fabricated under a severe molding condition on rubber particle agglomeration and molded specular gloss were studied. An agglomeration index (N_P) obtained by measuring particle size was used to determine the degree of rubber particle agglomeration. It was found that as graft level decreased, agglomeration increased. The rubber particle agglomeration also increased when graft molecular weight was increased. Lowering the particle size also led to a higher degree of agglomeration. Furthermore, increasing the compositional acrylonitrile mismatch between the grafted and matrix styrene-acrylonitrile copolymers increased the rubber particle agglomeration. Molecular structures that increased rubber particle agglomeration decreased the molded gloss. © 1996 John Wiley & Sons, Inc.     

Redefining security in public space: the case of LOVE park

By controlling the public spaces in which true human interaction occurs, planners and policymakers are challenging the fundamental desires of groups to forge social bonds and enhance their own sense familiarity with the environment. Security is not merely achieved through an understanding of territory but through acknowledgement and confrontation with individuals or groups maintaining diverse perspectives on the world.     

Adapting to change and uncertainty

Understanding how people adapt to change and uncertainty is critical to system design, and good system design expands the ability of people to adapt. Cognitive systems engineering (CSE) enables us to understand work domains, reveal expertise, and derive essential features for systems. This is valuable because the demand for rapidly evolving systems such as information and communication technology does not allow for long-term deliberation by system developers. The publication of work by Norman, Hollnagel and Woods, and Rasmussen in the early 1980s provides an opportunity to consider where CSE stands nearly 30?years since its inception. The papers in this special issue of Cognition, Technology and Work convey insights from authors who have substantial firsthand experience with the use of CSE to study human adaptation to changing, uncertain work settings. Their research demonstrates the current state of CSE, the potential for CSE to reveal how people adapt to change and uncertainty, and implications for the design of complex adaptive systems.     

Basic slit lamp techniques

Get the patient comfortable in the chin rest by manipulating the machine distance, elevation of the chair, and correct angling of the machine to the patient. Elderly patients need time and assistance to get positioned. Make sure they are elevated enough to get their foreheads against the headrest with comfort, or they will tend to easily drift backward during the exam, and your focusing power will be inaccurate. A little time taken positioning the patient can mean a more expedient and efficient exam. Align the eye marker on the headrest to the lateral canthus of the eye. Always speak calmly and logically to your patient. As soon as you have positioned the patient's chin on the rest, tell the patient to look at your right ear when examining the patient's right eye, and vice versa. The patient needs something to concentrate on as soon as positioned. Practice makes perfect. If you can visualize the three main components that make up the slit lamp--the head and chin rest for the patient, the microscope, and a housing for the illumination and the diaphragm controls--the machine becomes less overwhelming and better understood. Utilizing the biomicroscope effectively can allow great views of the dynamics in ocular anatomy and physiology.     

Changes in canine bladder perfusion with distension

Using a radioisotope-labeled microsphere technique, canine bladder perfusion was investigated. Blood flow was measured in in flaccid and distended conditions. A slight decrease in total bladder blood flow was recorded. There was a relative decrease in bladder mucosal flow with distension. There was no difference in perfusion of dome versus trigone.     

Methyl-Donors Can Induce Apoptosis and Attenuate Both the Akt and the Erk1/2 Mediated Proliferation Pathways in Breast and Lung Cancer Cell Lines

Dietary methyl-donors play important roles in physiological processes catalyzed by B vitamins as coenzymes, and are used for complementary support in oncotherapy. Our hypothesis was that methyl-donors can not only assist in tolerating cancer treatment but may also directly interfere with tumor growth and proliferation. Therefore, we investigated the proposed cancer inhibitory effects of methyl-donors (in a mixture of L-methionine, choline chloride, folic acid, and vitamin B12) on MCF7 and T47D breast cancer as well as A549 and H1650 lung cancer cell lines. Indeed, methyl-donor treatment significantly reduced the proliferation in all cell lines, possibly through the downregulation of MAPK/ERK and AKT signaling. These were accompanied by the upregulation of the pro-apoptotic Bak and Bax, both in MCF7 and H1650 cells, at reduced anti-apoptotic Mcl-1 and Bcl-2 levels in MCF7 and H1650 cells, respectively. The treatment-induced downregulation of p-p53(Thr55) was likely to contribute to protecting the nuclear localization and apoptosis inducing functions of p53. The presented features are known to improve the sensitivity of cancer therapy. Therefore, these data support the hypothesis, i.e., that methyl-donors may promote apoptotic signaling by protecting p53 functions through downregulating both the MAPK/ERK and the AKT pathways both in breast and lung adenocarcinoma cell lines. Our results can emphasize the importance and benefits of the appropriate dietary supports in cancer treatments. However, further studies are required to confirm these effects without any adverse outcome in clinical settings.