Interferometric interrogation of in-fiber Bragg grating sensorswithout mechanical path length scanning

We report the interrogation of a fiber Bragg grating (FBG) using an interferometer with a tilted mirror such that the optical path difference is a function of position on an array detector. Absolute measurements of mean resonant wavelength from the phase of the analytic signal of the spatial interferogram are determined, and a technique based on using a reference laser to compensate for performance degrading effects otherwise associated with spatially scanned interferometers is introduced. These measurements are not critically dependent on the accurate location of zero phase position. We have applied the technique to the absolute measurement of temperature-induced shifts in the grating resonant wavelength. A resolution of 0.025 nm for a spatially scanned optical path delay of only 200 μm was achieved. The technique has the potential for higher resolutions and for multiplexing     

A method for the selection of algorithms for form characterization of nominally spherical surfaces

This paper presents a method for the selection of algorithms for the form characterization of nominally spherical surfaces. The form characterization is applied to discrete data obtained from a three-dimensional (3-D) high-precision measurement system. In this paper, five sphere-fitting algorithms are outlined and compared. The fitting algorithms under investigation are: linear and nonlinear least-squares sphere fit, minimum zone sphere fit, four-point sphere fit, and sphere fit by error curve analysis. A method for selection of the best-fit algorithm, based on a spectral analysis of the surface irregularity is suggested and applied to the surface measurement of worn electrical switching contacts.     

Salivary fluoride levels in overdenture wearers after topical fluoride gel application

This study describes salivary fluoride levels after topical fluoride gel application on overdenture abutments. Fluoride levels were evaluated separately for the subjects with normal unstimulated salivary flow rate (n = 16) and for those with a low flow rate (n = 8). One drop of fluoride gel (Karigel-N, Lorvic) was placed in two abutment depressions of the duplicated overdenture, after which unstimulated whole saliva was collected for 30 minutes. Samples for fluoride analysis were taken at 5-minute intervals. Two additional samples were taken at 45 and 60 minutes. Fluoride concentration at the abutment-denture interface (remaining fluoride concentration) was measured at the end of the study. Salivary fluoride concentrations decreased gradually in both groups of subjects, but after 1 hour they remained at a higher level in subjects with low flow rates. Subjects' salivary flow rates correlated negatively with remaining fluoride concentration at the denture-tissue interface. Consequently, mean remaining fluoride concentration was significantly higher in subjects with low flow rate than in their normal counterparts.     

Effects of a permanent magnetic field on 45Ca2+ ion influx in excitable and inexcitable cells and proliferative activity of rat spleen cells

When experimental animals were exposed to Permanent Magnetic Fields with magnetic induction (B = 0.2 T), the influx of 45Ca2+ ions into brain cells was activated, but the influx of 45Ca2+ ions into spleen cells was depressed. Similar effect was observed upon incubation of brain and spleen tissues in magnetized physiological solution. Incorporation of 3H-thymidine into spleen cells increased upon direct exposition to magnetic field and upon exposition of the spleen in magnetized physiological solution as well.     

SIDS cases have increased levels of interleukin-6 in cerebrospinal fluid

Cerebrospinal fluid (CSF) from 20 infants who died of sudden infant death syndrome (SIDS), 7 cases of infectious death and 5 cases of violent death were examined with respect to concentrations of interleukin-6 (IL-6). The measurements were performed by ELISA. IL-6 levels in SIDS were significantly lower than in infectious death (p < 0.02), but significantly higher than in violent death (p < 0.02). Since IL-6 plays an important role in immune responses and may induce fever, the findings may suggest that immune activation plays a role in SIDS. The presence of cytokines in the central nervous system (CNS) may cause respiratory depression, especially in vulnerable infants.     

Why do adults with mucoviscidosis refuse a medically recommended course of intravenous antibiotic therapy?

OBJECTIVE: To better understand the needs of spouses who provide care to spinal cord injury (SCI) survivors, by comparing their self-perceptions and complaints with those of their partners with disabilities and with those of spouses who do not provide care. DESIGN: Survey, including demographics, health concerns questionnaire, and administration of the Center for Epidemiologic Studies Depression Scale (CES-D), the Perceived Stress Scale (PSS), the Life Satisfaction Index (LSI-Z), and the Quality of Life and Individual Needs Questionnaire. SETTING: Two British SCI treatment centers, serving a defined population-based catchment area. PARTICIPANTS: One hundred twenty-four spouses of a longitudinally followed sample of SCI survivors, all of whom had been injured 23 or more years when the study was conducted in 1993. OUTCOME MEASURES: Scores on the above standardized tests, and responses to survey questions. RESULTS: Spouses had more depressive affect (p < .001) than their partners with disabilities, as measured by the CES-D. On the PSS, they exhibited no significant differences. Compared with spouses who were not caregivers, the caregiving spouses reported more physical stress (p = .005), emotional stress (p = .011), burnout (p = .007), fatigue (p = .002), and anger and resentment (p = .029). On the CES-D, they had more symptoms of depressive affect (p = .004) and somatic depression (p = .005). CONCLUSIONS: Spouses of long-term SCI survivors who fulfill a caregiving role report more symptoms of stress and depression than their partners with disabilities and other spouses who are not caregivers.     

Application of a mechanistic model to study competitive inhibition of amino acid uptake by the lactating bovine mammary gland

A mathematical model is used to describe uptake by a countertransport system and subsequent flow of three amino acids (AA), Phe, Val, and Met, from arterial blood to milk protein in the mammary gland of a lactating cow. The model suggests that total uptake of all AA is higher than net uptake and that a large proportion of the incoming AA is released from the cell directly back to blood. The model is used to predict which of the three AA is limiting the rate of milk protein synthesis and the response to increased arterial concentration of the first-limiting AA. Simulations are performed to predict possible outcomes of several experimental protocols to AA infusion, which might be used to test in vivo the responsiveness of the bovine mammary gland to an altered arterial concentration of AA. Of the three AA considered, arterial Met concentration appears to be first-limiting. The infusion profile that gives the greatest response in milk protein synthesis rate alters the arterial profile of AA such that it is identical to that of proteins originating in the mammary gland. Model construction can be simplified by acknowledging normal biological constraints.     

Mitral valve replacement: randomized trial of St. Jude and Medtronic Hall prostheses

BACKGROUND: This study was designed to better define the merits of the bileaflet and tilting-disc valves. METHODS: We prospectively randomized 156 patients (mean age, 59 years) to receive either the St. Jude (n = 80) or the Medtronic Hall (n = 76) mitral valve prosthesis between September 1986 and December 1997. The two groups were not significantly different with respect to preoperative New York Heart Association class, left ventricular ejection fraction, incidence of mitral stenosis or insufficiency, extent of coronary artery disease, completeness of revascularization, or cross-clamp or bypass time. RESULTS: The operative mortality (11.2% versus 13.1%, St. Jude versus Medtronic Hall, respectively) and late mortality (27% versus 22%, St. Jude versus Medtronic Hall, respectively) were not significantly different. Follow-up was complete in all hospital survivors with a mean of 60.7 months (range, 1 to 133 months). The analysis of 10-year actuarial survival and freedom from valve-related events demonstrated no significant differences between the cohorts. Freedom from reoperation was higher in the St. Jude group (p < 0.01). Comparisons of patient functional status and echocardiographic hemodynamic parameters obtained at the time of follow-up demonstrated no significant differences between the two prostheses. CONCLUSIONS: This study suggests that there is no difference between the St. Jude and Medtronic Hall prostheses with respect to late clinical performance or hemodynamic results and therefore does not support the preferential selection of either prosthesis.