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  • 1
    Electronic Resource
    Electronic Resource
    Gaining light from silicon (2000)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 408 (2000), S. 411-412 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Silicon technology is so powerful that it pervades our everyday lives. Silicon chips are in our homes, our cars and even in some people's bodies. These microcircuits help us wake up on time, surf the Internet, and keep elderly hearts beating in a rhythmic fashion. Indeed, the scientific ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35044156
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  • 2
    Electronic Resource
    Electronic Resource
    Size-controlled percolation pathways for electrical conduction in porous silicon (1998)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 393 (1998), S. 443-445 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Silicon shows photo- and electroluminescence at visible wavelengths when chemically etched into a microporous network of ‘wires’ several nanometres thick. This raises the possibility of a silicon-based optoelectronic technology. The luminescence properties may be understood on the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/30924
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  • 3
    Electronic Resource
    Electronic Resource
    Recognition and Grading of Severely Distorted Geometric Shapes from within a Complex Figure (2000)
    Springer
    Pattern analysis and applications 3 (2000), S. 335-347 
    Details
    ISSN: 1433-755X
    Keywords: Keywords:Attributed-relational-graph; Freehand-line-drawings; Fuzzy-logic; Geometric-shapes; Pattern-recognition; Perceptual-organisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract. A novel method is presented for the location of highly distorted geometric shapes from within a complex free hand line drawing, such as those generated in neuropsychological figure copying tests. With such high levels of distortion, a shape can no longer be crisply categorised as either present or not, and so a grade of perceptual distortion is generated. Candidate shapes are located from within a graph representation of the pre-processed line drawing. These are then rated by a set of fuzzy rules based upon Gestalt principles of human visual perception. This produces a very flexible process that can be adapted to the required application. Test data was acquired from patient attempts at a specific neuropsychological test (the Rey Osterrieth Complex Figure), with the aim of locating certain rectangular, triangular and diamond components. These are the first steps of the automation of the traditional, clinical scoring of the test. Of the 140 test shapes used to evaluate the system, all but one was successfully located from within patient drawings of figure and of these only two were graded with an error greater than 10% of manually generated grades by independent raters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100440070005
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  • 4
    Electronic Resource
    Electronic Resource
    Interspecific and intraspecific variation in tree seedling survival: effects of allocation to roots versus carbohydrate reserves (1999)
    Springer
    Oecologia 121 (1999), S. 1-11 
    Details
    ISSN: 1432-1939
    Keywords: Key words Carbohydrate reserves ; Root allocation ; Tree seedling survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examined interspecific and intraspecific variation in tree seedling survival as a function of allocation to carbohydrate reserves and structural root biomass. We predicted that allocation to carbohydrate reserves would vary as a function of the phenology of shoot growth, because of a hypothesized tradeoff between aboveground growth and carbohydrate storage. Intraspecific variation in levels of carbohydrate reserves was induced through experimental defoliation of naturally occurring, 2-year-old seedlings of four northeastern tree species –Acer rubrum, A. saccharum, Quercus rubra, and Prunus serotina– with shoot growth strategies that ranged from highly determinate to indeterminate. Allocation to root structural biomass varied among species and as a function of light, but did not respond to the defoliation treatments. Allocation to carbohydrate reserves varied among species, and the two species with the most determinate shoot growth patterns had the highest total mass of carbohydrate reserves, but not the highest concentrations. Both the total mass and concentrations of carbohydrate reserves were significantly reduced by defoliation. Seedling survival during the year following the defoliation treatments did not vary among species, but did vary dramatically in response to defoliation. In general, there was an approximately linear relationship between carbohydrate reserves and subsequent survival, but no clear relationship between allocation to root structural biomass and subsequent survival. Because of the disproportionate amounts of reserves stored in roots, we would have erroneously concluded that allocation to roots was significantly and positively related to seedling survival if we had failed to distinguish between reserves and structural biomass in roots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050900
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  • 5
    Electronic Resource
    Electronic Resource
    Porosified Silicon Wafer Structures Impregnated With Platinum Anti-Tumor Compounds: Fabrication, Characterization, and Diffusion Studies (2000)
    Springer
    Biomedical microdevices 2 (2000), S. 265-272 
    Details
    ISSN: 1572-8781
    Keywords: porous silicon ; cis-platin ; drug delivery ; calcium phosphate ; carbo-platin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract In this work, the incorporation and characterization of cis-platin (cis-diammine dichloroplatinum(II)), carbo-platin [cis-diammine(cyclobutane-1,1-dicarboxylato] platinum(II)), and Pt(en)Cl2 (ethylenediamminedichloro platinum(II)) within layers of calcium phosphate on porous Si/Si substrates are described. These materials have been characterized by scanning electron microscopy, secondary ion mass spectrometry, and X-ray energy dispersive spectroscopy. The diffusion of platinum species from the doped calcium phosphate layers has also been investigated by UV-visible absorption spectrometry and inductively-coupled plasma spectroscopy. The influence of initial platinum concentration, the impact of thermal annealing of the calcium phosphate/porous Si/Si matrix, as well as the effect of varying the ligand coordination sphere of the Pt complex on its ability to be delivered to the surroundings have also been analyzed. For the case of cis-platin, it is found that increasing the concentration of platinum complex in the electrolyte during cathodic growth of calcium phosphate results in a relatively greater concentration of Pt incorporated into the calcium phosphate layers and a larger amount of Pt which subsequently can be delivered to the surrounding medium upon exposure to solvent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009951121205
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  • 6
    Electronic Resource
    Electronic Resource
    Responses of a small mammal community to heterogeneity along forest-old-field edges (1999)
    Springer
    Landscape ecology 14 (1999), S. 355-367 
    Details
    ISSN: 1572-9761
    Keywords: Blarina brevicauda ; competition ; ecological model system ; ecotones edge effects ; forest edge ; macrohabitat ; microhabitat ; Microtus pennsylvanicus ; old-field ; Peromyscus leucopus ; predation ; seed predation ; seedling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Despite the importance of edges effects in ecological systems, the causes and consequences of animal responses to habitat edges are largely unknown. We used three years of live-trapping and measures of the plant community around trap stations to explore the responses of white-footed mice (Peromyscus leucopus), meadow voles (Microtus pennsylvanicus), and short-tailed shrews (Blarina brevicauda) to forest-field edges in upstate New York. We found that capture probabilities of voles were highest in grass- and forb-dominated micro-habitats and in old-field zones distant from the forest edge. In contrast, capture probabilities of white-footed mice were highest in shrub-dominated microhabitats and in zones near the forest edge. Short-tailed shrews did not show strong micro- or macrohabitat associations. The responses by voles, the competitive dominant in our system, to variation along forest-field edges were more consistent across years than were those of the competitively inferior, white-footed mouse. Mice were less likely to use the old-field interiors when vole density was high than when it was low, suggesting competitive displacement of mice by voles. Finally, we found good agreement between the spatial activity patterns of mice and voles in old-fields and their impacts on patterns of survival of tree seeds and seedlings in concurrent studies. These results suggest that a dynamic interaction exists between the plant and animal communities along forest edges.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008093823391
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  • 7
    Electronic Resource
    Electronic Resource
    Structure, Mechanical Properties, and Mechanics of Intracranial Saccular Aneurysms (2000)
    Springer
    Journal of elasticity 61 (2000), S. 49-81 
    Details
    ISSN: 1573-2681
    Keywords: collagen structure ; stability ; rupture criterion ; growth mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Intracranial saccular aneurysms remain an enigma; it is not known why they form, why they enlarge, or why only some of them rupture. Nonetheless, there is general agreement that mechanics plays an essential role in each aspect of the natural history of these potentially deadly lesions. In this paper, we review recent findings that discount limit point instabilities under quasi-static increases in pressure and resonance under dynamic loading as possible mechanisms of enlargement of saccular aneurysms. Indeed, recent histopathological data suggest that aneurysms enlarge due to a stress-mediated process of growth and remodeling of collagen, the primary load-bearing constituent within the wall. We submit that advanced theoretical, experimental, and numerical studies of this process are essential to further progress in treating this class of pathologies. The purpose of this review is to provide background and direction that encourages elasticians to contribute to this important area of research.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010989418250
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  • 8
    Electronic Resource
    Electronic Resource
    Directional Wall Strength in Saccular Brain Aneurysms from Polarized Light Microscopy (2000)
    Springer
    Annals of biomedical engineering 28 (2000), S. 533-542 
    Details
    ISSN: 1573-9686
    Keywords: Cerebral aneurysms ; Birefringence ; Collagen organization ; Tissue mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The aneurysm wall, which must withstand arterial blood pressure, is composed of layered collagen. Wall strength is related to both collagen fiber strength and orientation. When the aneurysm enlarges, the amount and organization of the collagen fibers change, potentially increasing the risk of rupture. We studied the directional organization and molecular strength of the collagen fibers layer by layer across the walls of four aneurysms in order to measure their mechanical integrity. The technique incorporates the birefringent properties of collagen, enabling us to use linearly polarized light for measuring the orientation of the fibers, and the Sénarmont compensator to measure the birefringence and thus mechanical strength. Intact aneurysms were obtained at autopsy, fixed at physiological pressure, sectioned at 4 μm, and stained with 0.05% picrosirius red. By combining birefringence and orientation data we estimated tensile strength as a function of direction on the aneurysmal wall. The average breaking strength of the wall ranged from 0.73 to 1.9 MPa. Comparing the weakest to the strongest direction, the breaking strength varied by a factor of up to 2×, implying a significant degree of mechanical anisotropy. © 2000 Biomedical Engineering Society. PAC00: 8719Rr, 8719Uv, 8764Rr
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1114/1.292
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  • 9
    Electronic Resource
    Electronic Resource
    Light Emission from Highly Reflective Porous Silicon Multilayer Structures (2000)
    Springer
    Journal of porous materials 7 (2000), S. 209-213 
    Details
    ISSN: 1573-4854
    Keywords: porous silicon ; superlattices ; photoluminescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Porous silicon photoluminescence and electroluminescence can be controlled by periodically modulating the material porosity to form high quality multilayer stacks and microcavities. Important issues not yet fully addressed are (a) the precise role played by this microstructuring, given that the luminescence is distributed throughout the entire structure and that the low porosity layers are highly absorbing at short wavelengths, and (b) whether the quality of such microcavities could be sufficient to support lasing. Using both experimental and theoretical techniques, the emission and reflection properties of different porous silicon single and multilayer structures have been investigated in order to understand further and exploit the nature of light propagation within them.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009694906324
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  • 10
    Electronic Resource
    Electronic Resource
    Probing Carrier Transport in Porous Silicon with Synchrotron Radiation (2000)
    Springer
    Journal of porous materials 7 (2000), S. 115-118 
    Details
    ISSN: 1573-4854
    Keywords: porous silicon ; synchrotron radiation ; coulomb blocade
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In this paper we demonstrate that photo-electron emission excited by X-UV synchrotron radiation can be used as a “contactless” probe of the gross conduction processes in porous silicon. Moreover we demonstrate that this approach reveals the underlying conduction geometry. We show that conduction in porous silicon is to some degree controlled by percolation phenomena and finally present data which support the notion that the fundamental blocking process may be Coulomb Blockade [P.A. Lee, Physica B 189, 1–5 (1993); D. Ali and H. Ahmed, Appl. Phys. Lett. 64, 2119–2120 (1994)].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009667627705
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