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  • gamma scintigraphy  (5)
  • gastrointestinal transit  (4)
  • Behavior  (3)
  • geostatistics
  • Springer  (14)
  • 1990-1994  (9)
  • 1985-1989  (5)
  • 1955-1959
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Keywords
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  • Springer  (14)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical geology 22 (1990), S. 573-588 
    ISSN: 1573-8868
    Keywords: classification ; regionalization ; Bayes' theorem ; geostatistics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract The concept of multivariate classification of “geological objects” can be combined with the concept of regionalized variables to yield a procedure for typification of geological objects, such as rock units, well records, or samples. Numerical classification is followed by subdivision of the area of investigation, and culminates in a regionalization or mapping of the classification onto the plane. Regions are subdivisions of the map area which are spatially contiguous and relatively homogeneous in their geological properties. The probability of correct classification of each point within a region as being part of that region can be assessed in terms of Bayesian probability as a space-dependent function. The procedure is applied to subsurface data from western Kansas. The geologic properties used are quantitative variables, and relationships are expressed by Mahalanobis' distances. These functions could be replaced by other metrics if qualitative or binary data derived from geological descriptions or appraisals were included in the analysis.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical geology 19 (1987), S. 91-98 
    ISSN: 1573-8868
    Keywords: geostatistics ; kriging ; conditional simulation ; fast Fourier transform
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract This paper reviews the turning band method and fast Fourier transform method of producing a nonconditional simulation of a multinormal random function with a given covariance structure. A review of the two common methods of conditioning the simulation to honor the data shows that they are formally equivalent. Another method for directly pondering a conditional simulation based on the LU triangular decomposition of the covariance matrix is presented. Computational and implementation difficulties are discussed.
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  • 3
    ISSN: 1573-904X
    Keywords: gastrocolonic response ; gamma scintigraphy ; drug delivery to the colon ; tablets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The response of the colon to eating, the gastrocolonic response (GCR), may have important implications for the design of drug dosage forms for selective delivery to the colon. Therefore, the effect of meal composition on the GCR and its relation to the transit of non-disintegrating tablets has been investigated. Eight healthy male volunteers each received 5 × 6-mm radiolabeled nondisintegrating tablets, and the transit was followed using a gamma camera. When the tablets reached the ileocolonic region, each volunteer received a test meal (1000 kcal) containing 70% carbohydrate, 15% fat, and 15% protein. The subsequent movement of the tablets was then monitored. The study was repeated using a 70% fat meal and a 70% protein meal, so that the effects of a high-carbohydrate, a high-fat, and a high-protein meal on the GCR could be compared. The incidence of GCRs was similar after all meals. Thus, there appeared to be no effect of meal composition on the movement of the tablets into the colon. This implies that the ingestion of food may not necessarily stimulate the passage of material across the ileocecal junction and that other factors may also be involved.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical geology 19 (1987), S. 99-107 
    ISSN: 1573-8868
    Keywords: geostatistics ; simulation ; Toeplitz matrices ; block Toeplitz matrices ; matrix polynomial approximation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract An algorithm for producing a nonconditional simulation by multiplying the square root of the covariance matrix by a random vector is described. First, the square root of a matrix (or a function of a matrix in general) is defined. The square root of the matrix can be approximated by a minimax matrix polynomial. The block Toeplitz structure of the covariance matrix is used to minimize storage. Finally, multiplication of the block Toeplitz matrix by the random vector can be evaluated as a convolution using the fast Fourier transform. This results in an algorithm which is not only efficient in terms of storage and computation but also easy to implement.
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  • 5
    ISSN: 1573-904X
    Keywords: gastrointestinal transit ; pellet density ; floating formulations, gastric emptying
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The gastric emptying of pellets and single units of different densities has been followed in healthy subjects using the technique of gamma scintigraphy. The gastric emptying of the light pellets was affected by their buoyancy in the upper part of the stomach. However, the mean gastric emptying rates of pellets and single units were not significantly affected by density. Floating or buoyant delivery systems may have little advantage over conventional systems. The presence of food in the stomach was found to be the major factor in determining the gastric emptying of single units.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-5133
    Keywords: Behavior ; Buoyancy ; Orientation ; Resting ; Swimming ; Yolksac larvae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The behavioral capability of walleye pollock,Theragra chalcogramma free embryos and larvae to control vertical distribution was assessed by examining buoyancy during resting and swimming orientation and activity as they developed in complete darkness from hatching to first feeding readiness (1 to 7 d post hatching at 6° C). Free embryos exhibited positive geotaxis 1 d post hatching, actively swimming through a density gradient to remain in the lower water column. Activity increased with free embryo development and by 7 d post hatching, feeding-ready larvae reversed their vertical orientation, now exhibiting negative geotaxis as they migrated to the upper water column. The results indicate that even at the earliest developmental stages, walleye pollock possess the capability to control vertical distribution. Laboratory results are compared with patterns of vertical distribution observed in the sea.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Environmental biology of fishes 34 (1992), S. 421-424 
    ISSN: 1573-5133
    Keywords: Behavior ; Chum salmon ; Growth variation ; Oncorhynchus keta ; Sensory input ; Visual contact
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis This study tested the hypothesis that visual contact between fish may result in enhanced rates of growth in a schooling fish. Juvenile chum salmon, Oncorhynchus keta, were held singly and reared in isolation or in visual contact with conspecifics. Fish were fed at either a low (6% body weight d−1) or high (20% body weight d−1) ration for 42d. Specific rates of weight gain were 18% greater at low ration and 38% greater at high ration for fish in visual contract with conspecifics than for those held in isolation. The results demonstrate a selective advantage of visual cues associated with schooling behavior and suggest that the efficacy of growth models for schooling fishes may be enhanced by the consideration of social interactions which may facilitate growth.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Environmental biology of fishes 35 (1992), S. 105-108 
    ISSN: 1573-5133
    Keywords: Behavior ; Bioassay ; Light ; Starvation ; Swimming ; Survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The capability of unfed walleye pollock, Theragra chalcogramma, larvae to swim horizontally towards light was used as a sensitive, sublethal measure of larval condition. At 9°C, positive phototaxis and swimming ability of larvae was fully developed by 4–6 d after hatching, then decreased steadily until death by 12 d after hatching. This measure of larval condition corresponded closely with previously established benchmarks of larval condition, including first feeding, yolksac absorption, point of no return and death by starvation. The presence and timing of behavioral deficits associated with starvation, such as decreased ability to swim, feed and avoid predators, may have significant effects on the ability of larvae to vertically migrate, avoid predators and find and capture food.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-904X
    Keywords: gamma scintigraphy ; radiotelemetry, gastric emptying ; pharmaceutical dosage forms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The aim of the present study was to correlate the gastric emptying (GE) of nondisintegrating tablets with changes in gastrointestinal (GI) motility. Eight, healthy, male subjects each received 5 × 7-mm radiolabeled tablets, a radiolabeled meal, and a radiotelemetry capsule (RTC). Transit of the radiolabeled formulations was followed by gamma scintigraphy and the RTC detected contractile activity in the GI tract. The study demonstrated that 7-mm tablets can empty from the fed stomach, prior to the onset of interdigestive activity. Those tablets that were not emptied during fed activity were retained through the period of quiescence associated with the onset of the migrating myoelectric complex (MMC) and left the stomach during contractions associated with phase 2 and 3 activity. The RTC was retained in the stomach and was emptied only by large phase 3 contractions commonly termed the “housekeeper” wave. However, in one subject, the RTC was retained in the stomach for over 12 hr, during which time three distinct phase 3 complexes were monitored.
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  • 10
    ISSN: 1573-904X
    Keywords: bioavailability ; scintigraphy ; gastrointestinal transit ; controlled release ; phenylpropanolamine ; hydroxypropylmethylcellulose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two controlled-release hydroxypropylmethylcellulose (HPMC) matrix formulations, a single-unit and a multiple-unit system, have been evaluated in human volunteers. Both formulations contained the sympathomimetic drug phenylpropanolamine hydrochloride and each was radiolabeled with 111Inbound Amberlite IR 120 ion-exchange resin. The formulations were administered to each of six healthy male volunteers and gastrointestinal (GI) transit was monitored using a gamma camera. Serum samples were taken at set time intervals and assayed for phenylpropanolamine content, thus allowing blood drug levels to be correlated with the position of the dosage form in the GI tract. The multiple-unit system emptied from the stomach gradually over a period of about 180 min, when administered after a light breakfast, whereas the single-unit dosage forms had extremely variable gastric emptying times (range, 60 to 〉570 min). However, both formulations provided prolonged phenylpropanolamine blood levels. The differences in the blood profiles obtained with the two formulations were attributed to variations in their in vitro release rates and not to any differences in their GI transit times.
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