Neuronal protection by intraischemic brain perfusion: an electron microscopy study in the rat

Organ perfusion with bloodless solutions is an established clinical method for protecting the heart against ischemic damage. In our study, we evaluated the effects of intraischemic bloodless brain perfusion on postischemic ultrastructural neuronal changes in a model of severe incomplete forebrain ischemia produced by hemorrhagic hypotension combined with temporary carotid occlusion in the rat. Four groups of rats were compared. During an ischemic insult of 30 min, the brains of two groups were perfused via both external carotids with either a normosmolar normothermic magnesium-enriched perfusate (MgSO4, 30 mM; NaCl, 37 mM; mannitol, 180 mM; n = 10) or a normothermic normal saline solution (n = 9) at a rate of 6 ml/h. Two other groups (ischemia without perfusion, n = 8; no ischemia and no perfusion, n = 7) served as controls. After 30 min of ischemia, withdrawn blood for hemorrhagic hypotension was reinfused, the carotid arteries reopened, and the brains reperfused for 2 h. After perfusion-fixation, qualitative and quantitative evaluation of postischemic cell changes of hippocampal CA1 neurons was performed by electron microscopy. Brain perfusion with the magnesium-containing solution significantly protected neurons against ischemic cell changes and provided an ultrastructural pattern similar to that seen in the nonischemic control group. In contrast, brain perfusion with normal saline solution did not result in neuronal protection. We conclude that intraischemic intracarotid brain perfusion with magnesium-enriched perfusate protects hippocampal neurons significantly against ischemic cell changes in the early reperfusion period after transient severe forebrain ischemia.     

Detection of human papillomavirus DNA in CaSki and HeLa cells by fluorescent in situ hybridization. Analysis by flow cytometry and confocal laser scanning microscopy

CaSki and HeLa cell lines, isolated from human uterine carcinomas and containing integrated human papillomavirus (HPV) DNA type 16 and 18, respectively were used to evaluate the sensitivity of HPV-DNA detection on suspended cells by fluorescent in situ hybridization using flow cytometry and on corresponding cell deposits using confocal laser scanning microscopy (CLSM). HPV DNAs were detected in cell suspensions with biotinylated DNA probes and revealed with a three-step technique: a rabbit antibiotin antibody, a biotinylated goat anti-rabbit antibody and a streptavidin-fluorescein isothiocyanate complex. By flow cytometry, HPV DNA was detectable only in CaSki cells which contained about 600 copies of HPV DNA per cell. In HeLa cells, with only 20-50 copies of HPV DNA, flow cytometry could not detect HPV DNA, whereas CLSM permitted visualization of fluorescent labelling of HPV DNA hybrids. Furthermore, CLSM showed good preservation of cellular morphology and the nucleus was clearly recognizable after fluorescent in situ hybridization and counterstaining with propidium iodide. Moreover, this examination confirmed that the fluorescent foci were specifically confined to the cell nuclei.     

Infinite-horizon models for inventory control under yield uncertainty and disruptions

We consider a firm facing supply chain risk in two forms: disruptions and yield uncertainty. We demonstrate the importance of analyzing a sufficiently long time horizon when modeling inventory systems subject to supply disruptions. Several previous papers have used single-period newsboy-style models to study supply disruptions, and we show that such models underestimate the risk of supply disruptions and generate sub-optimal solutions. We consider one case where a firm's only sourcing option is an unreliable supplier subject to disruptions and yield uncertainty, and a second case where a second, reliable (but more expensive) supplier is available. We develop models for both cases to determine the optimal order and reserve quantities. We then compare these results to those found when a single-period approximation is used. We demonstrate that a single-period approximation causes increases in cost, under-utilizes the unreliable supplier, and distorts the order quantities that should be placed with the reliable supplier in the two-supplier case. Moreover, using a single-period model can lead to selecting the wrong strategy for mitigating supply risk.     

Photodegradation of poly(ethyleneoxide)/montmorillonite composite films

Poly(ethyleneoxide) (PEO) composites with SWy‐1 montmorillonite were prepared by mixing the polymer and the clay in aqueous colloidal solutions. Thin films of the composites were obtained by solvent evaporation and exposed to 254‐nm UV‐irradiation. The photodegradation was monitored by FTIR and the chain scission reaction was confirmed by measurement of average molecular weights using size exclusion chromatography. The rate of oxidation of pure PEO was much faster than that of the composites (SWy‐1/PEO). The SWy‐1 clay stabilizes the polymer against UV irradiation. This stabilization is due to two factors: on one side, the absorption of UV radiation by the clay, and on the other the scattering of the incident radiation by the particles; both contributing to minimize the degradation rate of the PEO present in the composites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Cortical visual impairment following bacterial meningitis: magnetic resonance imaging and visual evoked potentials findings in two cases

Cortical visual impairment (CVI) following bacterial meningitis is a very uncommon complication. Two children with CVI following bacterial meningitis are reported. Bacterial agents were Haemophilus influenzae type B in one and meningococci in the other child. Both children showed only insufficient recovery from CVI, mental retardation and residual neurological symptoms. Flash visual evoked potentials (VEP) showed preserved cortical response at onset of CVI. Re-evaluations several months later showed significantly reduced amplitudes, but normal latencies for P100. Thus, flash VEP does not allow prediction of visual outcome. MRI results have not been reported before. MRI at onset of diagnosis showed occipital parenchymal irregularities with enlarged sulci and subarachnoid spaces. Follow up MRI 15 months after onset of CVI in one patient showed marked atrophy of the occipital cortex, hyperintensities of the cortical white matter and no visible optic radiation. The MRI findings indicate hypoxic-ischaemic lesions in the border zone between the distribution of the great cerebral arteries.     

Microwave plasma oxidation of silicon

The stringent requirements of the next generation of VLSI will force the temperature of IC processing to a lower regime. One of the most important areas is the formation of gate and field dielectrics. Dopant re-distribution, stacking fault and dislocation generation as well as bird's-beak problems can be eliminated or minimized by low temperature oxygen microwave plasma anodization. This paper describes our investigation in the low pressure, low temperature oxidation of silicon using this technique. Oxidation rate dependence on anodization current, time, orientation, plasma power and temperature are measured. Properties of the plasma oxide was characteristized by thickness uniformity, refractive index, infrared absorption and C-V measurement. Discussion on the species responsible for the oxidation, the transport mechanisms and the factors that could affect the kinetics of the growth are presented. We conclude that the technique looks promising for the future.     

UV radiation exposure effects on the rain erosion resistance of coated monolithic poly(carbonate) transparencies

The results of a test program designed to evaluate the effects of accelerated UV radiation exposure on the rain erosion resistance of coated monolithic poly(carbonate) transparency materials are documented. Three different coatings for transparent poly(carbonate) were tested and examined. All materials were uniformly subjected to a velocity of 500 mile h^?1 and exposed to a simulated rainfall of 1 in h^?1 for specific time intervals. Selected specimens were exposed to accelerated UV radiation exposure prior to testing. Accelerated UV exposure resulted in increased coating removal as a function of rainfield exposure time and embrittlement of the poly(carbonate) substrate for two of the coatings examined. One coating apparently offered rain erosion protection as well as UV exposure protection. Data acquisition included visual observation of coating damage and removal, scanning electron microscopy examinations of the coatings and poly(carbonate) substrates and hazemeter measurements. The discussion includes rain erosion kinetics and rain erosion initiation and propagation processes.     

simVar: A Similarity-Influenced Question Selection Criterion for e-Sales Dialogs

Even though AI technologies like CBR have proved their strengths for intelligent sales support in EC applications, on-line customers often encounter e-sales systems that are hard to use. Before a search process is started, they either have to answer many annoying or irrelevant questions or they are faced with technical jargon of manufacturers they are not able to understand. On-line customers want personalised advice and adequate product offerings. Gaining sufficient information from the customer but also providing her with information at the right place is the key. Resulting from this fact, an automated communication process is needed that simulates the sales dialog between customers and human sales persons. This article proposes a method for question selection in e-sales dialogs based on the variance of the CBR system's inherent similarities. The method uses a similarity-influenced measure to reduce the number of questions required to find satisfactory products. Additionally, it is shown how questions can be selected on the level of abstraction appropriate to the customer's knowledge.     

Multilevel representation and transmission of real objects with progressive octree particles

We present a multilevel representation scheme adapted to storage, progressive transmission, and rendering of dense data sampled on the surface of real objects. Geometry and object attributes, such as color and normal, are encoded in terms of surface particles associated to a hierarchical space partitioning based on an octree. Appropriate ordering of surface particles results in a compact multilevel representation without increasing the size of the uniresolution model corresponding to the highest level of detail. This compact representation can progressively be decoded by the viewer and transformed by a fast direct triangulation technique into a sequence of triangle meshes with increasing levels of detail. The representation requires approximately 5 bits per particle (2.5 bits per triangle) to encode the basic geometrical structure. The vertex positions can then be refined by means of additional precision bits, resulting in 5 to 9 bits per triangle for representing a 12-bit quantized geometry. The proposed representation scheme is demonstrated with the surface data of various real objects.     

Quotients of Markov chains and asymptotic properties of the stationary distribution of the Markov chain associated to an evolutionary algorithm

In this work, a method is presented for analysis of Markov chains modeling evolutionary algorithms through use of a suitable quotient construction. Such a notion of quotient of a Markov chain is frequently referred to as “coarse graining” in the evolutionary computation literature. We shall discuss the construction of a quotient of an irreducible Markov chain with respect to an arbitrary equivalence relation on the state space. The stationary distribution of the quotient chain is “coherent” with the stationary distribution of the original chain. Although the transition probabilities of the quotient chain depend on the stationary distribution of the original chain, we can still exploit the quotient construction to deduce some relevant properties of the stationary distribution of the original chain. As one application, we shall establish inequalities that describe how fast the stationary distribution of Markov chains modeling evolutionary algorithms concentrates on the uniform populations as the mutation rate converges to 0. Further applications are discussed. One of the results related to the quotient construction method is a significant improvement of the corresponding result of the authors’ previous conference paper [Mitavskiy et al. (2006) In: Simulated Evolution and Learning, Proceedings of SEAL 2006, Lecture Notes in Computer Science v. 4247, Springer Verlag, pp 726–733]. This papers implications are all strengthened accordingly.