Numerical solution of the two-dimensional time-dependent multigroup equations

Also issued as a Ph. D. thesis in the Dept. of Nuclear Engineering, MIT, 1969"MIT-3903-1."Includes bibliographical references (leaves 60-61)Contract AT(30-1)-390

Why Are Students Not Majoring in Information Systems?

The purpose of this study was to examine some of the factors that influence and impact business students when they select their major and, more particularly, to examine why students are not majoring in information systems. Students in an entry level business class responded that they were more knowledgeable about careers in management, marketing, accounting, and finance than they were about careers in information systems. These business students indicated that they are looking for majors that will be interesting, provide them with job security initially and over their careers, and pay them well. The most important information sources used by these students in their major selection decision were information on college/department websites, brochures about the major, and information on the Internet. When asked why they were not majoring in information systems, the top two reasons given were not what I wanted to do and subject not of interest

Environmental Analysis of the Caddo River and its Tributaries: Comparison of Water Quality During 1992 with 1974-75

Environmental data related to water quality of the Caddo River and its tributaries were collected from March - October, 1992, and compared with data from August, 1974 - May, 1975. Bacterial, chemical and physical parameters were investigated at six river locations and thirteen tributary sites. Ammonia, nitrates, soluble phosphorus, turbidity and fecal coliform were significantly lower, and sodium and potassium were significantly higher in 1992 than during the previous study. Bacterial loading exceeded EPA criteria at some locations during both studies

Crossover between Thermally Assisted and Pure Quantum Tunneling in Molecular Magnet Mn12-Acetate

The crossover between thermally assisted and pure quantum tunneling has been studied in single crystals of high spin (S=10) uniaxial molecular magnet Mn12 using micro-Hall-effect magnetometry. Magnetic hysteresis and relaxation experiments have been used to investigate the energy levels that determine the magnetization reversal as a function of magnetic field and temperature. These experiments demonstrate that the crossover occurs in a narrow (0.1 K) or broad (1 K) temperature interval depending on the magnitude of the field transverse to the anisotropy axis.Comment: 5 pages, 4 figure

Morphologically distinct microtubule ends in the mitotic centrosome of Caenorhabditis elegans

During mitosis, the connections of microtubules (MTs) to centrosomes and kinetochores are dynamic. From in vitro studies, it is known that the dynamic behavior of MTs is related to the structure of their ends, but we know little about the structure of MT ends in spindles. Here, we use high-voltage electron tomography to study the centrosome- and kinetochore-associated ends of spindle MTs in embryonic cells of the nematode, Caenorhabditis elegans. Centrosome-associated MT ends are either closed or open. Closed MT ends are more numerous and are uniformly distributed around the centrosome, but open ends are found preferentially on kinetochore-attached MTs. These results have structural implications for models of MT interactions with centrosomes

Kochen-Specker Theorem for Finite Precision Spin One Measurements

Unsharp spin 1 observables arise from the fact that a residual uncertainty about the actual orientation of the measurement device remains. If the uncertainty is below a certain level, and if the distribution of measurement errors is covariant under rotations, a Kochen-Specker theorem for the unsharp spin observables follows: There are finite sets of directions such that not all the unsharp spin observables in these directions can consistently be assigned approximate truth-values in a non-contextual way.Comment: 4 page

MRI-based visual and haptic catheter feedback: simulating a novel system's contribution to efficient and safe MRI-guided cardiac electrophysiology procedures

Oral Presentationpublished_or_final_versio

An in vitro study of osteoblast vitality influenced by the vitamins C and E

Vitamin C and vitamin E are known as important cellular antioxidants and are involved in several other non-antioxidant processes. Generally vitamin C and vitamin E are not synthesized by humans and therefore have to be applied by nutrition. The absence or deficiency of the vitamins can lead to several dysfunctions and even diseases (e.g. scurvy). The main interest in this study is that vitamin C and E are known to influence bone formation, e.g. vitamin C plays the key role in the synthesis of collagen, the major component of the extracellular bone matrix. In the present study we evaluate the effect of ascorbic acid (vitamin C) and α-tocopherol (vitamin E) on the proliferation and differentiation of primary bovine osteoblasts in vitro. Starting from standard growth medium we minimized the foetal calf serum to reduce their stimulatory effect on proliferation. An improved growth and an increased synthesis of the extracellular matrix proteins collagen type I, osteonectin and osteocalcin was observed while increasing the ascorbic acid concentration up to 200 μg/ml. Furthermore the effects of α-tocopherol on cell growth and cell differentiation were examined, whereby neither improved growth nor increased synthesis of the extracellular matrix proteins collagen type I, osteonectin and osteocalcin were detected. Further investigations are necessary to target at better supportive effect of vitamins on bone regeneration, and healing