A model for research on cochlear hypoxia

The vessels emerging from one side of the basilar artery are supplied exclusively by the homolateral vertebral artery. Since blood flow is laminar through the vertebrobasilar system, mixing between two sides does not normally occur. Based on this fact, an experimental model for research on cochlear hypoxia is proposed and described. The animal's own blood flow in the vertebral artery is completely replaced by a stream of poorly oxygenated blood injected retrogradely through the ipsilateral axillary artery. In this way, the territory supplied by the vessels emerging from this side of the basilar artery, including the ear, is rendered hypoxic. The changes in the cochlear action potentials induced by the reduced oxygen supply are recorded by a chronically implanted electrode and analyzed.     

Liposome accumulation in ischaemic intestine following experimental mesenteric occlusion

Chromosome complements of murine thymic lymphomas induced by an alkylating agent N-methyl-N-nitrosourea (MNUA) were analyzed microscopically and karyotypically using the Q-banding technique. The chemical carcinogen was injected intraperitoneally into either neonatal or 7-week-old CFW/D mice. In addition, thymic lymphomas induced in 7-week-old AKR mice and thymic lymphomas developed spontaneously in this strain were also examined. All six lymphomas induced in neonatal CFW/D had hyperdiploid cell lines that accounted for 90% of the cells analyzed. Chromosome analysis of lymphomas induced in adult DFW/D mice showed that only out of nine lymphomas had predominantly hyperdiploid cell lines. The remaining five lymphomas had diploid modal chromosome number although they also carried a variant line characterized by 41 chromosomes. All eight lymphomas induced in adult AKR mice and six out of seven spontaneous AKR lymphomas showed predominantly diploid modal line. The remaining spontaneous lymphoma had a hyperdiploid stem line of 41 chromosomes. Microscopic and karyotypic analysis further identified trisomy 15 as the regular chromosome abnormality in the hyperdiploid cells in lymphomas of each group, whereas cells with diploid chromosome number had no detectable chromosome abnormality. Additional trisomies were also found, but their appearance was restricted to individual tumors. Thus, the incidence of trisomy 15 in lymphomas induced by MNUA in adult CFW/D and AKR mice, as well as in the spontaneous AKR lymphomas, is significantly lower than that in lymphomas induced in neonatal mice by the same carcinogen.     

Lighting controls: Survey of market potential

This study describes the impact of lighting management systems that dynamically control lights in accordance with the needs of occupants. Various control strategies are described: scheduling, tuning, lumen depreciation, and daylighting. From initial experimental results, the energy savings provided by each of the above strategies are estimated to be 26, 12, 14, and 15%, respectively.Based upon a cost of $0.05–0.10 per kWh for electric energy and a 2-, 3-, or 4-yr payback, target costs for a simple and a sophisticated lighting management system are found to be $0.24 and 1.89 per ft², respectively, for a cost-effective investment.A growth model, based upon an extrapolation of the increase in building stock since 1975, indicates that the commercial and industrial (C & I) building stock will grow from 40 × 10⁹ ft² in 1980 to about 67 × 10⁹ ft² by the year 2000. Even with the use of more efficient lighting components, the energy required for this additional C & I stock will be 307 × 10⁹ kWh compared to the 230 × 10⁹ kWh used today. Adopting controls would reduce this requirement to 243 × 10⁹ kWh, an increase of only 13 × 10⁹ kWh above current use.The specified information is used to analyze the economic impacts that using these systems will have on the lighting industry, end users, utility companies, and the nation's economy. A $1–4 × 10⁹ annual lighting control industry can be generated, creating many jobs. The estimated return on investment (ROI) for controls for end users would be between 19 and 38%. Utilities will be able to make smaller additions to capacity and invest less captial at 7–10% ROI. Finally, the annual energy savings, up to $3.4 × 10⁹ for end users and about $5 × 10⁹ for utilities, representing unneeded generating capacity, will be available to capitalize other areas of our economy.     

Blind deblurring of spiral CT images

To discriminate fine anatomical features in the inner ear, it has been desirable that spiral computed tomography (CT) may perform beyond their current resolution limits with the aid of digital image processing techniques. In this paper, we develop a blind deblurring approach to enhance image resolution retrospectively without complete knowledge of the underlying point spread function (PSF). An oblique CT image can be approximated as the convolution of an isotropic Gaussian PSF and the actual cross section. Practically, the parameter of the PSF is often unavailable. Hence, estimation of the parameter for the underlying PSF is crucially important for blind image deblurring. Based on the iterative deblurring theory, we formulate an edge-to-noise ratio (ENR) to characterize the image quality change due to deblurring. Our blind deblurring algorithm estimates the parameter of the PSF by maximizing the ENR, and deblurs images. In the phantom studies, the blind deblurring algorithm reduces image blurring by about 24%, according to our blurring residual measure. Also, the blind deblurring algorithm works well in patient studies. After fully automatic blind deblurring, the conspicuity of the submillimeter features of the cochlea is substantially improved.     

Macrocrack interaction with semi-infinite microcrack array

The collinear periodical array of microcracks ahead of a semi-infinite crack (macrocrack) is considered. A close form solution in terms of complex stress potentials is given, assuming that a remote, macroscale, stress intensity factor is given. The exact solution of the interaction of a macrocrack with a single microcrack is given.Results demonstrate that for relatively close location (with respect to crack length) of microcracks to the macrocrack tip, the microcrack spacing becomes important. For microcrack spacing (period) greater than 10 crack lengths the interaction can be taken as for a single microcrack, and, for distance greater than two microcrack lengths, the local stress intensity factor can be taken as equal to that remotely applied (for cases with crack spacing greater than two crack lengths).In other cases the macro-microcrack interaction is significant.

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Résumé On prend en considération le cas d'une rangée de fissures périodiques et colinéaires qui se forment en avant d'une fissure macroscopique semi-infinie. On propose une solution de forme fermée, exprimée en potentiels complexes de contraintes, et qui suppose l'existence d'un facteur d'intensité de contrainte s'exerçant à une échelle macroscopique. On fournit la solution exacte à l'interaction entre une macro-fissure et une simple microfissure.Les résultats présentés démontrent que, pour les micro-fissures relativement proches de l'extrémité de la macro-fissure, c'est leur espacement qui est important. Lorsque la période caractérisant l'espacement entre deux micro-fissures est supérieure ou égale à dix fois la longueur de la microfissure, l'interaction peut être assimilée à celle d'une micro-fissure simple. Lorsque la distance qui sépare la première micro-fissure de l'extrémité de la fissure est supérieure à deux fois la longueur de cette micro-fissure, et que la période entre deux micro-fissures successives excède deux fois leur longueur, l'interaction entre micro et macro-fissure peut être négligée pour le calcul du facteur d'intensité de contrainte à extrémité de la macro-fissure.Dans les autres configurations, l'interaction devient significative et ne peut être négligée.

     

Further evidence for the increased power of LOD scores compared with nonparametric methods

Platelet-derived growth factor (PDGF), a mitogen and chemoattractant for mesenchymal cells, occurs as cell-associated or released isoforms. To investigate their in vivo role, human keratinocytes, which normally synthesize both types of PDGF, were genetically modified to overexpress either wild-type PDGF-B (cell-associated) or the truncation mutant PDGF-B211 (released). Cells expressing the mutant isoform released 20 times more PDGF (145 ng/hour/10(7) cells) than cells expressing the wild-type isoform (6 ng/ hour/10(7) cells). When grafted as epithelial sheets onto athymic mice, modified cells formed a stratified epithelium and induced a connective tissue response that differed depending on the PDGF isoform expressed. Expression of PDGF-B211 induced a thick connective tissue with increased numbers of fibroblasts, mononuclear cells, and blood vessels evenly distributed throughout the connective tissue layer, whereas expression of PDGF-B induced a zone of fibroblasts and mononuclear cells localized to the interface of the epidermis and connective tissue, which often disrupted the continuity of the basement membrane. Immunostaining revealed that wild-type PDGF protein was deposited in the basement membrane region. These data suggest that the different binding properties of PDGF isoforms control the spatial organization of cellular events in regenerating mesenchymal tissue in vivo.     

Electrodeposited Quantum Dots. 6. Epitaxial Size Control in Cd(Se,Te) Nanocrystals on {111} Gold

Size control in epitaxial Cd(Se, Te) quantum dots (QDs) electrochemically deposited on {111} textured Au is achieved by mismatch tuning. The formation of QDs as a form of relaxation of heteroepitaxial strain energy is demonstrated. The increased lattice parameter resulting from incorporation of small amounts of Te in the CdSe lattice leads to reduced mismatch-induced strain energy and therefore larger QD size. While the QD interatomic spacings at the interface are shown to be unchanged due to the heteroepitaxy with the Au substrate, the perpendicular QD d-spacings (along the c-axis) strongly increase with increasing Te content due to strain relaxation.