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  • Articles  (56)
  • Articles: DFG German National Licenses  (56)
  • Springer  (56)
  • National Academy of Sciences
  • 1990-1994  (56)
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  • Articles  (56)
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  • 1
    Electronic Resource
    Electronic Resource
    The role of memory and concepts in learning (1992)
    Springer
    Minds and machines 2 (1992), S. 239-265 
    Details
    ISSN: 1572-8641
    Keywords: Representation ; cognitive architecture ; concepts ; machine learning ; game playing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Philosophy
    Notes: Abstract The extent to which concepts, memory, and planning are necessary to the simulation of intelligent behavior is a fundamental philosophical issue in Artificial Intelligence. An active and productive segement of the AI community has taken the position that multiple low-level agents, properly organized, can account for high-level behavior. Empirical research on these questions with fully operational systems has been restricted to mobile robots that do simple tasks. This paper recounts experiments with Hoyle, a system in a cerebral, rather than a physical, domain. The program learns to perform well and quickly, often outpacing its human creators at two-person, perfect information board games. Hoyle demonstrates that a surprising amount of intelligent behavior can be treated as if it were situation-determined, that often planning is unnecessary, and that the memory required to support this learning is minimal. Concepts, however, are crucial to this reactive program's ability to learn and perform.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02454222
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  • 2
    Electronic Resource
    Electronic Resource
    X-ray laser experiments using double foil nickel targets (1990)
    Springer
    Applied physics 50 (1990), S. 165-172 
    Details
    ISSN: 1432-0649
    Keywords: 42.60.By ; 42.60.Eb ; 52.25.Nr
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract New target geometries for collisional excitation X-ray laser experiments (in nickel) were proposed, analyzed, and experimentally studied on the Glass Development Laser (GDL). Experiments using a short line focus lens with new target geometries showed general agreement with predictions. The new geometries are designed to yield a higher gain and reduced refraction due to: (1) a higher plasma density, (2) a wider lateral density profile, and (3) a concave lateral density profile. These new geometries were: (1) two parallel exploding (thin) foils, irradiated from one side only, (2) two ablating (thick) foils, one of which is irradiated on its inner face, and (3) an exploding foil in front of an ablating foil, irradiated by a single laser beam incident on the thin foil. New experiments with a long line focus are in progress. The intensity ratio of Ne-like and F-like Ni lines is used to deduce the temperature, and these results together with the absolute intensity, yield the density profile. The results show improvement achieved with the new target geometries: the density is higher (leading to a higher gain), and the concave density profile results in collimation rather than divergence of the X-ray laser beam. Theoretical developments included: (1) prediction of high gain on new type transitions in neon like ions involving the excitation of an inner (2s) electron, and (2) development of a ray tracing code for an amplifying medium of varying (e.g., collimating) lateral density profile. Results using this code are shown for concave lateral density profiles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00357279
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  • 3
    Electronic Resource
    Electronic Resource
    The effect of a new vitamin D analog, 22-oxa-1α,25(OH)2D3, on bone mineral metabolism in normal male rats (1992)
    Springer
    Calcified tissue international 50 (1992), S. 521-523 
    Details
    ISSN: 1432-0827
    Keywords: 22-oxa-1α, 25 Dihydroxyvitamin D3 ; 1,25(OH)2D3 ; Bone histomorphometry ; Bone Gla protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Thein vivo effects of 22-oxa-1α, 25 dihydroxyvitamin D3 (OCT), on bone mineral metabolism were investigated in normal male Sprague-Dawley rats. The rats were administered either vehicle (control), low-dose OCT (25 ng/100 g body weight), or high-dose OCT (250 ng/100 g body wt). High-dose OCT increased serum ionized calcium (P〈0.05) and decreased serum parathyroid hormone (PTH) (P〈0.05) at all time points and increased serum bone Gla protein on days 7 and 28 (P〈0.05) compared with controls. Lowdose OCT decreased serum PTH at all the time points (P〈0.05) compared with controls. Tibial bone histomorphometry showed no significant differences between the two doses of OCT and controls. We found that OCT has minimal direct effects on bone metabolism in normal male rats in contrast to 1,25 dihydroxyvitamin D3. This property may be advantageous in the treatment with OCT of cell-proliferative diseases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582166
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  • 4
    Electronic Resource
    Electronic Resource
    A workbench for computational geometry (1994)
    Springer
    Algorithmica 11 (1994), S. 404-428 
    Details
    ISSN: 1432-0541
    Keywords: Algorithms ; Computational geometry ; Implementation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We describe the design and implementation of a workbench for computational geometry. We discuss issues arising from this implementation, including comparisons of different algorithms for constant factors, code size, and ease of implementation. The workbench is not just a library of computational geometry algorithms and data structures, but is designed as a geometrical programming environment, providing tools for: creating, editing, and manipulating geometric objects; demonstrating and animating geometric algorithms; and, most importantly, for implementing and maintaining complex geometric algorithms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01187021
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  • 5
    Electronic Resource
    Electronic Resource
    The projective independence axiom (1994)
    Springer
    Economic theory 4 (1994), S. 189-215 
    Details
    ISSN: 1432-0479
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Summary A new axiom for preference orderings over lotteries, called the projective independence axiom, is formulated. Given suitable continuity and monotonicity assumptions, the axiom implies that utility is either in the weighted utility class or is quadratic in probabilities. The betweenness axiom is used to distinguish between these two classes of functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01221200
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  • 6
    Electronic Resource
    Electronic Resource
    An improved noninfections murine skin model of organized granulomatous inflammation (1991)
    Springer
    Cellular and molecular life sciences 47 (1991), S. 273-277 
    Details
    ISSN: 1420-9071
    Keywords: Skin granuloma model ; granulomatous inflammation ; T-cell independent ; granuloma ; angiotensin-converting enzyme ; proline-specific endopeptidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An improved model of granulomatous inflammation in skin was developed by second passage skin grafting of isolated, lyophilized skin granulomas, originally elicited in naive mice by inoculations of lyophilized hepatic schistosome egg granulomas. The tissue reaction is caused by a single exposure to a noninfectious, acellular granulomagenic stimulus and occurs in healthy mice free of systemic disease. The model should prove useful for isolation of granuloma initiation factor(s). Furthermore, because there is a time lag before new granuloma formation begins, a window exists for analytical dissection of the initiation process. In this study we described the responses of host cells by autoradiography, and light and electron microscopy. The activity of angiotensin-converting enzyme and proline-specific endopeptidase showed a modulation during granuloma formation. In addition we found that severe immunosuppression with high dose cyclosporine therapy did not alter granuloma formation, supporting the idea that initiation of organized granulomas is T-cell independent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01958158
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  • 7
    Electronic Resource
    Electronic Resource
    Toward an Ideal Trainer (1994)
    Springer
    Machine learning 15 (1994), S. 251-277 
    Details
    ISSN: 0885-6125
    Keywords: training ; competition ; game playing ; reliability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This paper demonstrates how the nature of the opposition during training affects learning to play two-person, perfect information board games. It considers different kinds of competitive training, the impact of trainer error, appropriate metrics for post-training performance measurement, and the ways those metrics can be applied. The results suggest that teaching a program by leading it repeatedly through the same restricted paths, albeit high quality ones, is overly narrow preparation for the variations that appear in real-world experience. The results also demonstrate that variety introduced into training by random choice is unreliable preparation, and that a program that directs its own training may overlook important situations. The results argue for a broad variety of training experience with play at many levels. This variety may either be inherent in the game or introduced deliberately into the training. Lesson and practice training, a blend of expert guidance and knowledge-based, self-directed elaboration, is shown to be particularly effective for learning during competition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022637925775
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  • 8
    Electronic Resource
    Electronic Resource
    Toward an ideal trainer (1994)
    Springer
    Machine learning 15 (1994), S. 251-277 
    Details
    ISSN: 0885-6125
    Keywords: training ; competition ; game playing ; reliability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This paper demonstrates how the nature of the opposition during training affects learning to play two-person, perfect information board games. It considers different kinds of competitive training, the impact of trainer error, appropriate metrics for post-training performance measurement, and the ways those metrics can be applied. The results suggest that teaching a program by leading it repeatedly through the same restricted paths, albeit high quality ones, is overly narrow preparation for the variations that appear in real-world experience. The results also demonstrate that variety introduced into training by random choice is unreliable preparation, and that a program that directs its own training may overlook important situations. The results argue for a broad variety of training experience with play at many levels. This variety may either be inherent in the game or introduced deliberately into the training. Lesson and practice training, a blend of expert guidance and knowledge-based, self-directed elaboration, is shown to be particularly effective for learning during competition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00993346
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  • 9
    Electronic Resource
    Electronic Resource
    Lack of change of cancellous bone volume with short-term use of the new immunosuppressant rapamycin in rats (1993)
    Springer
    Calcified tissue international 53 (1993), S. 45-52 
    Details
    ISSN: 1432-0827
    Keywords: Rapamycin ; Bone mineral metabolism ; Bone Gla protein ; Immunosuppressants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Immunosuppressants have adverse effects on bone mineral metabolism in animal and human studies, with corticosteroids producing low-turnover osteopenia, and cyclosporin-A (CsA) producing high-turnover osteopenia. Rapamycin (RAPA) is a new immunosuppressant reported to be at least 10 times more potent than CsA, and acts via a different pathway to CsA and the other new immunosuppressant FK506. This study investigated the effects of RAPA on bone mineral metabolism in the rat. Forty-two, 10-week-old, male Sprague Dawley rats were divided into three groups, and treated according to the following protocol: group A (control) received RAPA vehicle by daily gavage for 14 days (n = 12); group B (high dose RAPA) received RAPA 2.5 mg/kg/day by daily gavage for 14 days (n = 15); group C (low dose RAPA) received RAPA 1.25 mg/kg/day by daily gavage for 14 days (n = 15). Rats were weighed and bled on days 0, 7, and 14 for measurement of blood ionized calcium, bone Gla protein (BGP), parathyroid hormone (PTH), and 1,25(OH)2D. Tibial bone histomorphometry was determined on day 14 after double-calcein labeling. Weight gain was similar in the two groups treated with RAPA compared with control animals. High-dose RAPA (group B) transiently depressed serum BGP levels on day 7, with elevated blood ionized calcium levels on day 7, and lowered 1,25(OH)2D levels on day 14. Serum PTH levels were unchanged. Low dose RAPA (group C) did not affect calciotropic hormones. Histomorphometric analyses of tibial metaphyses revealed that parameters of bone formation and resorption were not significantly different in the groups treated with RAPA (group B and C) compared with control animals (group A). Trabecular bone volume (BV/TV) in group B (high-dose RAPA) (15.39 ± 1.01%) and C (low-dose RAPA) (15.38 ±0.57%) was not significantly altered compared with group A (control) (16.42 ± 0.86%). Short-term treatment with RAPA, unlike CsA, does not result in excess resorption and loss of bone volume. The depressed serum 1,25(OH)2D levels seen with high-dose RAPA therapy may adversely effect bone mineral metabolism in the long term.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01352014
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  • 10
    Electronic Resource
    Electronic Resource
    Ability of vertebral dimensions from a single radiograph to identify fractures (1992)
    Springer
    Calcified tissue international 51 (1992), S. 95-99 
    Details
    ISSN: 1432-0827
    Keywords: Epidemiology ; Vertebral fractures ; Morphology ; Prospective studies ; Fracture prevalence, incidence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary It has been proposed that vertebral dimensions be used to objectively identify vertebral fractures, permitting standardization of methodology for comparisons between studies. In this report, we evaluate the ability of various vertebral dimensions and ratios to identify “abnormal” vertebrae. As no “gold standard” exists for prevalent vertebral fractures, we examined the ability of cross-sectional dimensions (at a single point in time) to detect fractured vertebrae that had been identified from changes in dimensions compared with previous radiographs. Theoretically, a cutoff of 3 SD below the mean will rarely misclassify normal vertebrae as fractured (specificity=99.9%). However, we found that this cutoff correctly identified only about 70% of the incident fractures. A less stringent criterion (2 SD below the mean; theoretical specificity=97.7%) identified about 85–90% of true fractures. Dividing by stature or other vertebral heights sometimes yielded marginal improvements in the ability of the anterior or posterior height dimensions to diagnose fractures. The results suggest that the true fracture prevalence may sometimes be substantially higher than suggested by cross-sectional vertebral measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298495
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