Marks of French influence in Goethe's works.

Thesis (M.A.)--Boston Universit

Mercury in Fish from Northeastern Minnesota Lakes: Historical Trends, Environmental Correlates, and Potential Sources

ABSTRACT-High mercury concentrations in fish of some Minnesota lakes and rivers were first noted in 1971. Major anthropogenic sources of mercury to Minnesota rivers generally have been identified and controlled, but it has been difficult to identify mercury sources to remote northeastern Minnesota lakes containing fish with elevated mercury levels. Analysis of sediments from these lakes suggests that mercury deposition has increased by a factor of about 3.5 since white settlement in the state. Because the increase is spatially constant across northeastern Minnesota, atmospheric pollution appears to be responsible for the increase. Given that fish mercury varies considerably among lakes, local environmental processes apparently control the conversion of inorganic mercury into the methylmercury found in fish. Mercury levels in Minnesota fish are related to wa~er chemistry, which in turn is influenced by watershed geology. Fish from lakes in limestonerich watersheds are less likely to have high mercury levels than lakes in low-alkalinity regions. lakes with colored water are more likely to contain fish with high mercury levels. Trend analysis shows that mercury levels in fish increased significantly between the 1930s and 1980s (comparison between museum specimens and recent samples) and between the 1970s and 1980s. Rates of increase are highest in low-alkalinity lakes

Arousal Responses to Specific Structured Classroom Activities and Events as Determined by Cardiac Telemetry

The purposes of this study were (1) to determine the effects of specific structured classroom activities and events on the cardiac rates of students in the classroom, (2) to determine whether or not there was a detectable difference in the cardiac rates of students involved in structured classroom activities and events and cardiac rates of students not so involved, and (3) to determine the effects on the cardiac rates of students involved in two techniques of attaining student involvement and attention to a classroom discussion or topic

Fatigue-Life Prediction Methodology Using Small-Crack Theory

This paper reviews the capabilities of a plasticity-induced crack-closure model to predict fatigue lives of metallic materials using 'small-crack theory' for various materials and loading conditions. Crack-tip constraint factors, to account for three-dimensional state-of-stress effects, were selected to correlate large-crack growth rate data as a function of the effective-stress-intensity factor range (delta K(eff)) under constant-amplitude loading. Some modifications to the delta k(eff)-rate relations were needed in the near-threshold regime to fit measured small-crack growth rate behavior and fatigue endurance limits. The model was then used to calculate small- and large-crack growth rates, and to predict total fatigue lives, for notched and un-notched specimens made of two aluminum alloys and a steel under constant-amplitude and spectrum loading. Fatigue lives were calculated using the crack-growth relations and microstructural features like those that initiated cracks for the aluminum alloys and steel for edge-notched specimens. An equivalent-initial-flaw-size concept was used to calculate fatigue lives in other cases. Results from the tests and analyses agreed well

Spatial and Temporal Patterns of Mercury Accumulation in Lacustrine Sediments across the Laurentian Great Lakes Region

Data from 104 sediment cores from the Great Lakes and “inland lakes” in the region were compiled to assess historical and recent changes in mercury (Hg) deposition. The lower Great Lakes showed sharp increases in Hg loading c. 1850-1950 from point-source water dischargers, with marked decreases during the past half century associated with effluent controls and decreases in the industrial use of Hg. In contrast, Lake Superior and inland lakes exhibited a pattern of Hg loading consistent with an atmospheric source - gradual increases followed by recent (post-1980) decreases. Variation in sedimentary Hg flux among inland lakes was primarily attributed to the ratio of watershed area: lake area, and secondarily to a lake’s proximity to emission sources. A consistent region-wide decrease (~20%) of sediment Hg flux suggests that controls on local and regional atmospheric Hg emissions have been effective in decreasing the supply of Hg to Lake Superior and inland lakes

Using the Chinese version of Memorial Delirium Assessment Scale to describe postoperative delirium after hip surgery

Objective:: Memorial Delirium Assessment Scale (MDAS) assesses severity of delirium. However, whether the MDAS can be used in a Chinese population is unknown. Moreover, the optimal postoperative MDAS cutoff point for describing postoperative delirium in Chinese remains largely to be determined. We therefore performed a pilot study to validate MDAS in the Chinese language and to determine the optimal postoperative MDAS cutoff point for delirium. Methods:: Eighty-two patients (80 ± 6 years, 21.9% male), who had hip surgery under general anesthesia, were enrolled. The Confusion Assessment Method (CAM) and Mini-Mental State Examination (MMSE) were administered to the patients before surgery. The CAM and MDAS were performed on the patients on the first, second and fourth postoperative days. The reliability and validity of the MDAS were determined. A receiver operating characteristic (ROC) curve was used to determine the optimal Chinese version MDAS cutoff point for the identification of delirium. Results:: The Chinese version of the MDAS had satisfactory internal consistency (α = 0.910). ROC analysis obtained an average optimal MDAS cutoff point of 7.5 in describing the CAM-defined postoperative delirium, with an area under the ROC of 0.990 (95% CI 0.977–1.000, P < 0.001). Conclusions:: The Chinese version of the MDAS had good reliability and validity. The patients whose postoperative Chinese version MDAS cutoff point score was 7.5 would likely have postoperative delirium. These results have established a system for a larger scale study in the future

Enhancing Acceleration Radiation from Ground-State Atoms via Cavity Quantum Electrodynamics

When ground state atoms are accelerated through a high Q microwave cavity, radiation is produced with an intensity which can exceed the intensity of Unruh acceleration radiation in free space by many orders of magnitude. The cavity field at steady state is described by a thermal density matrix under most conditions. However, under some conditions gain is possible, and when the atoms are injected in a regular fashion, the radiation can be produced in a squeezed state

Preoperative cerebrospinal fluid β-Amyloid/Tau ratio and postoperative delirium

Objective: The neuropathogenesis of postoperative delirium remains unknown. Low cerebrospinal fluid (CSF) β-amyloid protein (Aβ) and high CSF Tau levels are associated with Alzheimer's disease. We, therefore, assessed whether lower preoperative CSF Aβ/Tau ratio was associated with higher incidence and greater severity of postoperative delirium. Methods: One hundred and fifty-three participants (71 ± 5 years, 53% men) who had total hip/knee replacement under spinal anesthesia were enrolled. CSF was obtained during initiation of spinal anesthesia. The incidence and severity of postoperative delirium were determined by Confusion Assessment Method (CAM) and Memorial Delirium Assessment Scale (MDAS) on postoperative day 1 and 2. Aβ40, Aβ42, and Tau levels in the CSF were measured by enzyme-linked immunosorbent assay. The relationships among these variables were determined, adjusting for age and gender. Results: Participants in the lowest quartile of preoperative CSF Aβ40/Tau and Aβ42/Tau ratio had higher incidence (32% vs. 17%, P = 0.0482) and greater symptom severity of postoperative delirium (Aβ40/Tau ratio: 4 vs. 3, P = 0.034; Aβ42/Tau ratio: 4 vs. 3, P = 0.062, the median of the highest MDAS score) as compared to the combination of the rest of the quartiles. The preoperative CSF Aβ40/Tau or Aβ42/Tau ratio was inversely associated with MDAS score (Aβ40/Tau ratio: −0.12 ± 0.05, P = 0.014, adj. −0.12 ± 0.05, P = 0.018; Aβ42/Tau ratio: −0.65 ± 0.26, P = 0.013, adj. −0.62 ± 0.27, P = 0.022). Interpretation Lower CSF Aβ/Tau ratio could be associated with postoperative delirium, pending confirmation of our preliminary results in further studies. These findings suggest potential roles of Aβ and/or Tau in postoperative delirium neuropathogenesis