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  • 21
    Electronic Resource
    Electronic Resource
    Estimation of a Product of Two Regression Lines (1996)
    New York : Cambridge University Press
    Econometric theory 12 (1996), S. 589-590 
    Details
    ISSN: 0266-4666
    Source: Cambridge Journals Digital Archives
    Topics: Economics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1017/S0266466600006915
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  • 22
    Electronic Resource
    Electronic Resource
    Low Environmental Temperatures or Pharmacologic Agents That Produce Hypothermia Decrease Methamphetamine Neurotoxicity in Mice (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 765 (1995), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1995.tb16610.x
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  • 23
    Electronic Resource
    Electronic Resource
    Investigation of actinomycete diversity in the tropical rainforests of Singapore (1999)
    Springer
    Journal of industrial microbiology and biotechnology 23 (1999), S. 178-187 
    Details
    ISSN: 1476-5535
    Keywords: Keywords: actinomycete diversity; phylogeny; rRNA; tropical rainforest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Five thousand actinomycetes were isolated from soil samples collected from rainforests in Singapore and the generic identities of these isolates were determined by using a procedure that combined morphological, chemotaxonomic and 16S rDNA sequence-based phylogenetic analyses. Actinomycetes belonging to a total of 36 genera were identified. The most abundant isolates are members of Streptomyces, Micromonospora, Actinoplanes, Actinomadura, Nonomuria, Nocardia and Streptosporangium. By phylogenetic analysis of 16S rDNA sequences of our isolates together with those of known actinomycete species, we also evaluated the species diversity of several genera including Streptomyces, Micromonospora, Nonomuria, and Actinomadura. We found that: first, the tropical isolates are present in most clades represented by known species; and second, many tropical isolates form new clades distant from the known species, indicating the presence of unidentified taxa at both species and genus levels. Based on these results, we conclude that actinomycete diversity in the tropical rainforest is very great and should represent an excellent source for discovery of novel bioactive compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/sj.jim.2900723
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  • 24
    Electronic Resource
    Electronic Resource
    Rescheduling on a single machine with part-type dependent setup times and deadlines (1997)
    Springer
    Annals of operations research 70 (1997), S. 93-113 
    Details
    ISSN: 1572-9338
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract We consider the problem of rescheduling a facility modeled as a single machine in the face of newly arrived jobs with part-type dependent setup times. The facility contains a number of jobs that have been assigned due dates and scheduled so as to meet them. We wish to insert the new jobs into the existing schedule in a manner that will minimize the disruption of the jobs in the system and minimize the total weighted completion time or the maximum completion time of the new jobs. We provide a polynomial-time algorithm for the maximum completion time problem, prove that the total weighted completion time problem is NP-hard in the strong sense and study several of its special cases. In particular, we show that the case with reverse-agreeable weights (of which the unit weight problem is a special case) can be solved in polynomial time when the number of part types is fixed. We also present two heuristics for the problem with arbitrary weights and develop data-dependent worst-case error bounds. Extensive computational experiments show that the heuristics consistently obtain near-optimal solutions in very reasonable CPU times.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018955111939
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  • 25
    Electronic Resource
    Electronic Resource
    Morphometric Analysis of Type I Collagen Fibrils in the Osteoid of Osteogenesis Imperfecta (1999)
    Springer
    Calcified tissue international 65 (1999), S. 390-395 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Osteogenesis imperfecta — Morphometry — Type I collagen — Collagen diameter.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Electron microscopy and morphometric measurements of bone osteoid collagen diameter from 42 osteogenesis imperfecta (OI) patients and 25 age- and site-matched controls were carried out. Although the mean diameter did not correlate well with the severity of the disease, it related well with the clinical types and revealed collagen fibrils of reduced diameter in the osteoid of all OI types. Thus, OI type II (the severest type) demonstrated the smallest diameter (45 nm), followed by OI type I (the mildest form) with a mean diameter of 57 nm. The diameter obtained for type III (67 nm) and type IV (64 nm) was lower than the normal control mean diameter (73 nm) but did not show a statistical difference. The thinner fibrils observed in OI bone may be unable to provide nucleating and scaffolding sites for mineral propagation and may play a role in the fragility of bone in this disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900719
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  • 26
    Electronic Resource
    Electronic Resource
    Aminoguanidine does not inhibit the initial phase of experimental diabetic retinopathy in rats (1995)
    Springer
    Diabetologia 38 (1995), S. 269-273 
    Details
    ISSN: 1432-0428
    Keywords: Key words Diabetic retinopathy ; rat model ; aminoguanidine ; glycation ; retinal basement membrane.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have previously shown that long-term administration of aminoguanidine, an inhibitor of advanced glycosylation product formation, reduces the extent of experimental diabetic retinopathy in the rat by 85 %. In order to determine whether the residual retinopathy that developed despite aminoguanidine was attributable to advanced glycation endproduct formation, a time-course study was performed in three different groups of male Wistar rats: non-diabetic controls (NC), streptozotocin-diabetic controls (DC) and streptozotocin-diabetic rats treated with aminoguanidine HCL, 50 mg/100 ml drinking water (D-AG). Eyes were obtained at 24, 32, 44 and 56 weeks of diabetes/treatment duration and morphologic evaluation was done on retinal digest preparations. At 56 weeks, retinal basement membrane thickness was additionally measured. After 24 weeks of diabetes, the number of acellular capillaries was significantly elevated in DC (44.6 ± 5.7/mm2 of retinal area, NC 19.6 ± 4.9; p 〈 0.001) and increased continuously over time (DC 56 weeks 87.4 ± 15.1; p 〈 0.001 vs DC 24 weeks). In contrast, acellular capillaries in D-AG increased over the first 24 weeks and then remained constant for the rest of the study (D-AG 24 weeks 35.7 ± 5.18; p 〈 0.01 vs NC 24 weeks and NS vs DC 24 weeks; D-AG 56 weeks 42.0 ± 6.20; p NS vs D-AG 24 weeks). Diabetes-associated pericyte loss (DC 24 weeks 2310 ± 170/mm2 of capillary area; NC 24 weeks 3120 ± 190; p 〈 0.001; DC 56 weeks 1570 ± 230; NC 56 weeks 2960 ± 50; p 〈 0.001) was significantly prevented by aminoguanidine after diabetic-like changes over the initial 24 weeks (D-AG 24 weeks 2450 ± 75; p NS vs DC 24 weeks; D-AG 56 weeks 2350 ± 90; p 〈 0.001 vs DC 56 weeks). At 56 weeks, aminoguanidine treatment was associated with a 67.4 % reduction in retinal basement membrane thickening. This time-course study demonstrates that aminoguanidine prevents the progression of experimental diabetic retinopathy, and suggests that non AG-inhibitable mechanisms are involved in the initial phase of diabetic retinopathy. [Diabetologia (1995) 38: 269–273]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400629
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  • 27
    Electronic Resource
    Electronic Resource
    Aminoguanidine does not inhibit the initial phase of experimental diabetic retinopathy in rats (1995)
    Springer
    Diabetologia 38 (1995), S. 269-273 
    Details
    ISSN: 1432-0428
    Keywords: Diabetic retinopathy ; rat model ; aminoguanidine ; glycation ; retinal basement membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have previously shown that long-term administration of aminoguanidine, an inhibitor of advanced glycosylation product formation, reduces the extent of experimental diabetic retinopathy in the rat by 85%. In order to determine whether the residual retinopathy that developed despite aminoguanidine was attributable to advanced glycation endproduct formation, a time-course study was performed in three different groups of male Wistar rats: non-diabetic controls (NC), streptozotocin-diabetic controls (DC) and streptozotocin-diabetic rats treated with aminoguanidine HCL, 50 mg/100 ml drinking water (D-AG). Eyes were obtained at 24, 32, 44 and 56 weeks of diabetes/treatment duration and morphologic evaluation was done on retinal digest preparations. At 56 weeks, retinal basement membrane thickness was additionally measured. After 24 weeks of diabetes, the number of acellular capillaries was significantly elevated in DC (44.6±5.7/mm2 of retinal area, NC 19.6±4.9; p〈0.001) and increased continuously over time (DC 56 weeks 87.4±15.1; p〈0.001 vs DC 24 weeks). In contrast, acellular capillaries in D-AG increased over the first 24 weeks and then remained constant for the rest of the study (D-AG 24 weeks 35.7±5.18; p〈0.01 vs NC 24 weeks and NS vs DC 24 weeks; D-AG 56 weeks 42.0±6.20; p NS vs D-AG 24 weeks). Diabetes-associated pericyte loss (DC 24 weeks 2310±170/mm2 of capillary area; NC 24 weeks 3120±190; p〈0.001; DC 56 weeks 1570±230; NC 56 weeks 2960±50; p〈0.001) was significantly prevented by aminoguanidine after diabetic-like changes over the initial 24 weeks (D-AG 24 weeks 2450±75; p NS vs DC 24 weeks; D-AG 56 weeks 2350±90; p〈0.001 vs DC 56 weeks). At 56 weeks, aminoguanidine treatment was associated with a 67.4% reduction in retinal basement membrane thickening. This time-course study demonstrates that aminoguanidine prevents the progression of experimental diabetic retinopathy, and suggests that non AG-inhibitable mechanisms are involved in the initial phase of diabetic retinopathy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400629
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  • 28
    Electronic Resource
    Electronic Resource
    Learning and Updating of Uncertainty in Dirichlet Models (1997)
    Springer
    Machine learning 26 (1997), S. 43-63 
    Details
    ISSN: 0885-6125
    Keywords: Beta distribution ; Dirichlet distribution ; Dirichlet conjugate priors ; evidence propagation ; parameter estimation ; prior assessment of hyperparameters ; time series.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In this paper we analyze the problem of learning and updating of uncertainty in Dirichlet models, where updating refers to determining the conditional distribution of a single variable when some evidence is known. We first obtain the most general family of prior-posterior distributions which is conjugate to a Dirichlet likelihood and we identify those hyperparameters that are influenced by data values. Next, we describe some methods to assess the prior hyperparameters and we give a numerical method to estimate the Dirichlet parameters in a Bayesian context, based on the posterior mode. We also give formulas for updating uncertainty by determining the conditional probabilities of single variables when the values of other variables are known. A time series approach is presented for dealing with the cases in which samples are not identically distributed, that is, the Dirichlet parameters change from sample to sample. This typically occurs when the population is observed at different times. Finally, two examples are given that illustrate the learning and updating processes and the time series approach.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007372016040
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  • 29
    Electronic Resource
    Electronic Resource
    An electron probe X-ray microanalytical study of bone mineral in osteogenesis imperfecta (1995)
    Springer
    Calcified tissue international 56 (1995), S. 118-122 
    Details
    ISSN: 1432-0827
    Keywords: Osteogenesis imperfecta ; Mineral ; Composition ; Microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract A semiquantitative electron probe X-ray microan-alytical (XRMA) technique, in conjunction with transmission electron microscopy, was used to compare the calcium to phosphorus (Ca/P) molar ratios in calcium phosphate standards of known composition, in normal bone and in bone from patients with osteogenesis imperfecta (OI). Using a modified routine processing and resin embedding schedule, the measured Ca/P molar ratio of calcium phosphates standards of known composition were found to correlate well with the Ca/P molar ratio based on their respective chemical formulae. This technique was then used to compare the Ca/P molar ratio in normal human bone and in OI bone. The Ca/P ratio values for normal bone (Ca/P=1.631) correlated well with those for chemically prepared hydroxyapatite (Ca/P=1.602), but in bone from OI patients, the Ca/P molar ratio was significantly lower (Ca/P=1.488). This study has shown that there is a lower Ca/P molar ratio in OI bone compared with normal, matched bone. This suggests that the mineral deviates from the carbanoapatite usually found in bone. Isomorphous substitutions in the carbanoapatite lattice could account for this although this study has neither proved nor disproved this. The altered bone mineral is an-other factor that could contribute to the increased fracture rate observed in OI.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296342
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  • 30
    Electronic Resource
    Electronic Resource
    Abnormal Mineral Composition of Osteogenesis Imperfecta Bone as Determined by Electron Probe X-ray Microanalysis on Conventional and Cryosections (1999)
    Springer
    Calcified tissue international 65 (1999), S. 11-15 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Osteogenesis imperfecta — Abnormal mineral composition — Cryosections — Electron probe X-ray microanalysis.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Osteogenesis imperfecta (OI) is a genetic disorder of the connective tissue characterized by frequent bone fractures. The cause of bone fragility is still unknown even though substantial work on collagen has been done. We measured the calcium to phosphorus ratio (Ca/P) of bone mineral from 35 OI bone samples and 25 age- and site-matched control specimens, using electron probe X-ray microanalysis in the transmission electron microscope. Ultra-thin cryosections and conventionally prepared resin sections were used. Cryo-ultramicrotomy avoids any possible artifactual demineralization that may occur in conventional aqueous media. The Ca/P ratio obtained by these two methods was compared and there was no statistical difference between them. The results were differentiated according to the clinical types of OI for the first time. The Ca/P ratio of OI bone mineral was lower than normal in both resin and cryosections, and mirrored the severity of the disease. OI type II had the lowest ratio (Ca/P = 1.49) compared with normal age- and site-matched controls (Ca/P = 1.69). This abnormal mineral composition in OI type II could be a contributory factor to bone fragility in OI bone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00005829
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