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  • 1
    Electronic Resource
    Electronic Resource
    The spatial patterns of β/A4 deposit subtypes in Alzheimer's disease (1993)
    Springer
    Acta neuropathologica 86 (1993), S. 36-41 
    Details
    ISSN: 1432-0533
    Keywords: Alzheimer's disease ; β/A4 deposits ; Morphological types ; Spatial pattern ; Clustering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The spatial patterns of diffuse, primitive, classic (cored) and compact (burnt-out) subtypes of β/A4 deposits were studied in coronal sections of the frontal lobe and hippocampus, including the adjacent gyri, in nine cases of Alzheimer's disease (AD). If the more mature deposits were derived from the diffuse deposits then there should be a close association between their spatial patterns in a brain region. In the majority of tissues examined, all deposit subtypes occurred in clusters which varied in dimension from 200 to 6400 μm. In many tissues, the clusters appeared to be regularly spaced parallel to the pia or alveus. The mean dimension of the primitive deposit clusters was greater than those of the diffuse, classic and compact types. In about 60% of cortical tissues examined, the clusters of primitive and diffuse deposits were not in phase, i.e. they alternated along the cortical strip. Clusters of classic deposits appeared to be distributed independently of the diffuse deposit clusters. Cluster size of the primitive deposits was positively correlated with the density of the primitive deposits in a tissue but no such relationship could be detected for the diffuse deposits. This study suggested that there was a complex relationship between the clusters of the different subtypes of β/A4 deposits. If the diffuse deposits do give rise to the primitive and classic varieties then factors unrelated to the initial deposition of β/A4 in the form of diffuse plaques were important in the formation of the mature deposits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00454896
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  • 2
    Electronic Resource
    Electronic Resource
    The identification of pathological subtypes of Alzheimer's disease using cluster analysis (1994)
    Springer
    Acta neuropathologica 88 (1994), S. 60-66 
    Details
    ISSN: 1432-0533
    Keywords: Alzheimer's disease ; Neuropathological criteria ; Clustering analysis ; Disease subtypes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A culster analysis was performed on 78 cases of Alzheimer's disease (AD) to identify possible pathological subtypes of the disease. Data on 47 neuropathological variables, inculding features of the gross brain and the density and distribution of senile plaques (SP) and neurofibrillary tangles (NFT) were used to describe each case. Cluster analysis is a multivariate statistical method which combines together in groups, AD cases with the most similar neuropathological characteristics. The majority of cases (83%) were clustered into five such groups. The analysis suggested that an initial division of the 78 cases could be made into two major groups: (1) a large group (68%) in which the distribution of SP and NFT was restricted to a relatively small number of brain regions, and (2) a smaller group (15%) in which the lesions were more widely disseminated throughout the neocortex. Each of these groups could be subdivided on the degree of capillary amyloid angiopathy (CAA) present. In addition, those cases with a restricted development of SP/NFT and CAA could be divided further into an early and a late onset form. Familial AD cases did not cluster as a separate group but were either distributed between four of the five groups or were cases with unique combinations of pathological features not closely related to any of the groups. It was concluded that multivariate statistical methods may be of value in the classification of AD into subtypes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00294360
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  • 3
    Electronic Resource
    Electronic Resource
    The spatial patterns of b/A4 deposit subtypes in Down's syndrome (1994)
    Springer
    Acta neuropathologica 88 (1994), S. 353-358 
    Details
    ISSN: 1432-0533
    Keywords: Key words Alzheimer's disease ; Down's syndrome ; β/A4 deposits ; Spatial pattern ; Clustering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The spatial patterns of diffuse, primitive and classic β/A4 deposits were studied in coronal sections of the hippocampus and adjacent gyri in 11 cases of Down's syndrome (DS) varying in age from 38 to 67 years. The objectives of the study were first, to compare the spatial patterns of β/A4 deposits revealed in DS with those reported in cases of Alzheimer's disease (AD) and second, to study how the spatial patterns of β/A4 deposits may develop in the tissue. The spatial patterns revealed in DS exhibited a number of similarities with those reported in AD: (1) the range and frequency of the different types of spatial pattern revealed were similar, (2) β/A4 deposits occurred in clusters and in many cortical tissues, the clusters were distributed in a regular pattern parallel to the pia, (3) the clusters of diffuse and primitive β/A4 deposits occurred in an alternating pattern along the cortex, and (4) the clusters of classic β/A4 deposits were not correlated with the clusters of the diffuse and primitive deposits. Primitive deposits may develop from the diffuse deposits in regions of the cortex where extracellular paired helical filaments were formed. However, clusters of the classic β/A4 deposits, which are formed in older cases, appear to develop independently of the diffuse and primitive deposits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310379
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  • 4
    Electronic Resource
    Electronic Resource
    Dynamics of vibrationally excited ozone formed by three-body recombination. I. Spectroscopy (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 5202-5208 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Spectrally resolved infrared fluorescence near 10 μm from vibrationally excited O3(ν3) has been observed in a cryogenic reactor facility at low pressure. The excited O3(v) is formed principally by three-body recombination of O and O2 in flowing, microwave-discharged O2/Ar mixtures at 1 Torr and 80 K. The spectral resolution is sufficient to permit identification and assignment of band centers for up to five quanta of stretching excitation. The observed transition frequencies are consistent with those predicted from a Darling–Dennison perturbation treatment. The spectra, which sample the recombination/deactivation sequence in its early to middle stages, indicate surprisingly little intermode coupling, being predominantly ν3 in character. There is also evidence of O3(v) excitation by near-resonant V–V coupling between O3 and O2(v=2). The spectroscopic analysis of the data is described, and considerations for scaling the spontaneous transition probabilities with vibrational level are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453688
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  • 5
    Electronic Resource
    Electronic Resource
    Dynamics of vibrationally excited ozone formed by three-body recombination. II. Kinetics and mechanism (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 5209-5221 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Spectrally resolved infrared chemiluminescence from vibrationally excited ozone, O3(v), has been used to study the reaction kinetics of O3(v) in discharged O2/Ar mixtures at ∼1 Torr and 80–150 K. Dependences of the excited state number densities on temperature and O2 mole fraction indicate O3(v) is formed primarily by three-body recombination of O with O2 and is destroyed by rapid chemical reaction with O. Several secondary excitation reactions involving vibrationally and electronically excited O2 are also indicated. The data are treated with a detailed steady-state analysis of the discharge kinetics, to extract estimates for rate coefficients of the key elementary reactions. The effective "quasinascent'' state distribution in recombination is also inferred; this distribution shows selective recombination into the asymmetric stretching mode, but an apparently statistical (i.e., collisionally scrambled) behavior among the vibrational states within that mode. The results are discussed in terms of the detailed dynamics of three-body recombination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453689
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  • 6
    Electronic Resource
    Electronic Resource
    Infrared spectra (2–16 μm) of ArI Rydberg emission from a microwave discharge plasma (1985)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 82 (1985), S. 681-692 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Infrared (2–16 μm) emission from Ar Rydberg atoms, excited in a conventional low-pressure microwave discharge plasma, has been observed in the cryogenic COCHISE reactor/spectrometer facility. The observed spectrum is very complex but is identifiable using the detailed energy level structure and optical selection rules for ArI. Detailed transition probabilities for dipole-allowed transitions between 2 and 16 μm were computed using the Coulomb approximation. Comparisons of observed and predicted spectra show that substantial long wavelength infrared (LWIR) emission (∼12 μm) arises from Rydberg states near the ionization limit; these states must have kinetically enhanced populations in order to account for the observed emission intensities. The results are interpreted in terms of a radiative/collisional cascade sequence initiated by dissociative recombination of Ar+2 with energetic electrons in the active discharge.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.448545
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  • 7
    Electronic Resource
    Electronic Resource
    Quantifying the pathology of neurodegenerative disorders: quantitative measurements, sampling strategies and data analysis (2003)
    Oxford, UK : Blackwell Science Ltd
    Histopathology 42 (2003), S. 0 
    Details
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The use of quantitative methods has become increasingly important in the study of neurodegenerative disease. Disorders such as Alzheimer's disease (AD) are characterized by the formation of discrete, microscopic, pathological lesions which play an important role in pathological diagnosis. This article reviews the advantages and limitations of the different methods of quantifying the abundance of pathological lesions in histological sections, including estimates of density, frequency, coverage, and the use of semiquantitative scores. The major sampling methods by which these quantitative measures can be obtained from histological sections, including plot or quadrat sampling, transect sampling, and point-quarter sampling, are also described. In addition, the data analysis methods commonly used to analyse quantitative data in neuropathology, including analyses of variance (anova) and principal components analysis (PCA), are discussed. These methods are illustrated with reference to particular problems in the pathological diagnosis of AD and dementia with Lewy bodies (DLB).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2559.2003.01601.x
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  • 8
    Electronic Resource
    Electronic Resource
    Characterisation of Aeromonas strains and species by pulsed field gel electrophoresis and principal components analysis (1999)
    Oxford, UK : Blackwell Science Ltd
    Journal of fish diseases 22 (1999), S. 0 
    Details
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Aeromonas genomes were investigated by restriction digesting chromosomal DNA with the endonuclease XbaI, separation of restriction fragments by pulsed field gel electrophoresis (PFGE) and principal components analysis (PCA) of resulting separation patterns. A. salmonicida salmonicida were unique amongst the isolates investigated. Separation profiles of these isolates were similar and all characterised by a distinct absence of bands in the 250kb region. Principal components analysis represented these strains as a clearly defined homogeneous group separated by insignificant Euclidian distances. However, A. salmonicida achromogenes isolates in common with those of A. hydrophila and A. sobria were shown by principal components analysis to be more heterogeneous in nature. Fragments from these isolates were more uniform in size distribution but as demonstrated by the Euclidian distances attained through PCA potentially characteristic of each strain. Furthermore passaging of Aeromonas isolates through an appropriate host did not greatly modify fragment separation profiles, indicative of the genomic stability of test aeromonads and the potential of restriction digesting/PFGE/PCA in Aeromonas typing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2761.1999.00186.x
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  • 9
    Electronic Resource
    Electronic Resource
    A STUDY OF PHYSICAL ADSORPTION AT VERY LOW PRESSURES USING ULTRAHIGH VACUUM TECHNIQUES (1963)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 67 (1963), S. 2000-2007 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100804a012
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  • 10
    Electronic Resource
    Electronic Resource
    An electrostatic analyzer for surface structure measurements by low-energy-ion-scattering (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 3273-3279 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A cylindrical electrode electrostatic analyzer has been designed for surface structure measurements which has sufficient sensitivity that shadowing/blocking data can be obtained without significantly damaging the surface structure. A modification to the standard π/(square root of)2 design compensates for that part of the spread in the ion energies due to elastic scattering kinematics. The analyzer is small enough to fit inside a standard 25 cm diameter UHV chamber on a turntable, allowing angular distribution measurements over a wide range of scattering angles. An example of a shadowing/blocking angular scan of a clean Si(100) surface is shown. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145493
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