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  • Springer  (89)
  • Wiley  (73)
  • 1990-1994  (162)
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  • 1
    Electronic Resource
    Electronic Resource
    Reproduction by virgin queen fire ants in queenless colonies: Comparative study of three taxa (Solenopsis richteri, hybridS. invicta/richteri, S. geminata) (Hymenoptera: Formicidae) (1993)
    Springer
    Insectes sociaux 40 (1993), S. 283-293 
    Details
    ISSN: 1420-9098
    Keywords: Fire ants ; virgin queens ; reproduction ; execution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the fire ant,Solenopsis invicta, some winged virgin queens are known to shed their wings (dealate) upon removal of the mated mother queen. These virgin queens then develop their ovaries and begin to lay eggs, thereby foregoing the option of leaving on mating flights and attempting to found their own colonies. Such a response of virgin queens to queenlessness has not been reported for other ants. In order to determine if virgin queens of some other fire ants (subgenusSolenopsis) would respond in the same way, experiments were conducted onS. richteri, hybridS. invicta/richteri andS. geminata, a member of a species complex different from that of the other taxa. Just as inS. invicta, virgin queens ofS. richteri and the hybrid dealated and began to lay eggs within days of the removal of the queen. In addition, workers executed many of the reproductively active virgin queens, a phenomenon also found inS. invicta. In contrast, virgin queens ofS. geminata did not dealate or quickly begin to lay eggs upon separation from the queen. Reasons for the variability in the response of virgin queens of the different species may be 1) higher probability of reproductive success for unmated dealated queens compared to normal claustral founding inS. invicta andS. richteri linked to relatively frequent loss of the mother queen; or 2) phylogenetic constraint.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01242364
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  • 2
    Electronic Resource
    Electronic Resource
    An experimental examination into the design of decentralized methods to solve the assignment problem with and without money (1994)
    Springer
    Economic theory 4 (1994), S. 11-40 
    Details
    ISSN: 1432-0479
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Summary An experimental examination of the assignment problem, matching individuals to positions or slots, is conducted in which various assignment mechanisms are analyzed. Generalized versions of both the Vickrey and English auctions are designed to solve the assignment problem along with oridinal ranking mechanisms (serial dictator and “funny” money system). The generalized auctions result in efficient allocations. In contrast, the ordinal ranking mechanisms, which require no monetary transfers, are significantly less efficient in their assignments. However, the efficient allocations obtained from the competitive bidding processes are at the expense of consumers' surplus since demanders retain significantly larger profits with the ordinal ranking mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01211117
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  • 3
    Electronic Resource
    Electronic Resource
    Relative nutritional value of ciliate protozoa and algae as food forDaphnia (1990)
    Springer
    Microbial ecology 19 (1990), S. 199-210 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relative importance of autotrophic flagellates, desmids, cyanobacteria, and ciliates as food forDaphnia magna was examined using cohort life tables. Each cohort was fed a single food type at a given concentration, and comparisons among each type were made. Algal feeding treatments included three levels of young (7 to 14 days old)Chlamydomonas reinhardi (Chlorophyta, Chlamydomonadacae), two levels of senescent (〉 14 days old)C. reinhardi, two levels ofCryptomonas sp. (Chlorophyta, Cryptomonadacae), two levels ofStaurastrum sp. (Chlorophyta, Desmidacae), four levels of young (7 to 15 days old) or senescent (〉 15 days old)Microcystis aeruginosa (Cyanophyta, Chlorococcacae), and a no-food treatment. The ciliatesCyclidium sp. andParamecium caudatum were also presented at concentrations of 1 or 102 cells/ml, as well as mixtures ofC. reinhardi (103/ml) andCyclidium (1/ml) orP. caudatum (1/ml).Daphnia growth, reproduction, and survivorship were highest whenC. reinhardi orCryptomonas were the food source, while those starved or fedM. aeruginosa had shorter survivorship and lower growth and reproduction.Daphnia grew and had high survivorship when fedP. caudatum, but even though eggs were produced, most were aborted after 2 or 3 days.Staurastrum andCyclidium produced intermediate growth and survivorship, but reproduction was seen only in the 103 Staurastrum/ml treatment. Carbon and nitrogen content were general indicators of nutritional value. However, growth, reproduction, and survivorship were higher in some cohorts fed treatments containing relatively low levels of carbon and nitrogen. Other cohorts were short-lived and did not reproduce, despite being fed much higher levels of carbon and nitrogen. The results also suggest that green algae are nutritionally valuable forDaphnia, whereas cyanobacteria are not. As measured by life-table parameters, the nutritional value of ciliates was variable, with some being poor food sources. Thus, the potential of ciliates as a trophic link between microbial production and higher trophic levels may vary with the ciliate community structure. Our results suggest that ciliates alone were insufficient as a food source to supportDaphnia population growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02012100
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  • 4
    Electronic Resource
    Electronic Resource
    Relationship between phototrophy and phagotrophy in the mixotrophic chrysophytePoterioochromonas malhamensis (1990)
    Springer
    Microbial ecology 19 (1990), S. 97-109 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The time scales involved in the transition between phototrophic and phagotrophic modes of nutrition were examined in the mixotrophic chrysophytePoterioochromonas malhamensis. Phagotrophy began almost immediately when bacteria were added to phototrophically growing cultures of the alga, and chlorophylla concentration per cell in these cultures decreased over a 24-hour period. Chlorophyll concentrations per cell began to increase when bacteria were grazed to a density of approximately 106 ml−1, but after more than 24 hours they had not returned to the higher chlorophyll concentrations observed in the phototrophically grown cultures. Bacterivory was the dominant mode of nutrition in all cultures containing heat-killed bacteria. Photosynthesis did not contribute more than ≈7% of the total carbon budget of the alga when in the presence of abundant heat-killed bacteria. Bacterial density was the primary factor influencing the ability ofP. malhamensis to feed phagotrophically, while light intensity, pH, and the presence of dissolved organic matter had no effect on phagotrophy. We conclude thatP. malhamensis is capable of phagotrophy at all times. In contrast, phototrophy is inducible in the light during starvation and is a long-term survival strategy for this mixotrophic alga (i.e., it operates on time scales greater than a diel cycle).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02015056
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  • 5
    Electronic Resource
    Electronic Resource
    Absorption of theophylline from a new theophylline controlled-release capsule (1991)
    Springer
    European journal of clinical pharmacology 40 (1991), S. 319-320 
    Details
    ISSN: 1432-1041
    Keywords: Theophylline ; controlled-release formulation ; absorption ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315219
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  • 6
    Electronic Resource
    Electronic Resource
    On a bottleneck bipartition conjecture of Erdős (1992)
    Springer
    Combinatorica 12 (1992), S. 317-321 
    Details
    ISSN: 1439-6912
    Keywords: 05 C 35
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract For a graphG, let γ(U,V)=max{e(U), e(V)} for a bipartition (U, V) ofV(G) withUυV=V(G),UφV=Ø. Define γ(G)=min(U,V ){γ(U,V)}. Paul Erdős conjectures $$\gamma (G)/e(G) \leqslant {1 \mathord{\left/ {\vphantom {1 4}} \right. \kern-\nulldelimiterspace} 4} + O\left( {1/\sqrt {e(G)} } \right)$$ . This paper verifies the conjecture and shows $$\gamma (G)/e(G) \leqslant {1 \mathord{\left/ {\vphantom {1 4}} \right. \kern-\nulldelimiterspace} 4}\left( {1 + \sqrt {2/e(G)} } \right)$$ .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01285820
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  • 7
    Electronic Resource
    Electronic Resource
    Book reviews (1993)
    Springer
    Public choice 75 (1993), S. 379-401 
    Details
    ISSN: 1573-7101
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01053447
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  • 8
    Electronic Resource
    Electronic Resource
    Broadband ultrasound attenuation and dual energy X-ray absorptiometry in patients with hip fractures: Which technique discriminates fracture risk (1994)
    Springer
    Calcified tissue international 54 (1994), S. 466-469 
    Details
    ISSN: 1432-0827
    Keywords: Osteoporosis ; Ultrasound ; Hip fractures ; Bone density ; DXA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract There is considerable interest in predicting risk of hip fracture in order to allow targeting of preventive care. This study aimed to determine which of two methods best discriminates a hip fracture population from controls. Fifty women with fractured neck of femur, and 50 control subjects were scanned using dual energy X-ray absorptiometry (DXA) of the spine and hip and broadband ultrasound attenuation (BUA) of the os calcis. Significant differences between the two populations could be found for both DXA and BUA, with BUA showing the largest percentage difference (27%). The mean z-scores showed that BUA had the lowest, with the exception of DXA trochanter. However, no significant difference between BUA and DXA trochanter Z-scores was found. A receiver operator characteristic (ROC) analysis showed that BUA has a superior sensitivity and specificity compared with DXA measurements, with DXA of the hip being better than the spine. This retrospective study shows that BUA is a better discriminator of hip fracture than DXA lumbar spine of DXA hip, which may have important implications for predicting those at risk of future hip fracture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334324
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  • 9
    Electronic Resource
    Electronic Resource
    Social organization in deer: Implications for localized management (1991)
    Springer
    Environmental management 15 (1991), S. 809-814 
    Details
    ISSN: 1432-1009
    Keywords: White-tailed deer ; Odocoileus virginianus ; Behavior ; Philopatry ; Population management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Populations of white-tailed deer (Odocoileus virginianus) inhabiting many state and national parks and suburban areas have grown to the point that they conflict with human activities. Conflicts range from destruction of vegetation through browsing to public perception that diseases carried by deer pose threats to human health. Traditional modes of hunting to control populations are inappropriate in many of these areas because of intense human development and activity. This article explores an alternative approach for population reduction based on deer social organization. Female white-tailed deer are highly philopatric and female offspring remain near their dams for life. This suggests that a population expands slowly as a series of overlapping home ranges in a form analogous to the petals on a rose. Incorporating the rose petal concept into a model of population growth shows that removal of deer by family unit can potentially alleviate conflicts in localized areas for as many as 10–15 yr.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02394818
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  • 10
    Electronic Resource
    Electronic Resource
    Aqueous Ethylcellulose Dispersion of Ethylcellulose. I. Evaluation of Coating Process Variables (1993)
    Springer
    Pharmaceutical research 10 (1993), S. 525-534 
    Details
    ISSN: 1573-904X
    Keywords: factorial experimental design ; response surface methodology (RSM) ; ethylcellulose ; Surelease ; ibuprofen ; fluid-bed coating ; latex film ; microindentation hardness ; zero-order drug release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Formulation and process variables play an important role in the film-forming properties of coating polymers. Three selected independent coating process variables, namely, percent solids content in the coating polymeric dispersion, inlet-air temperature, and spray rate of the polymeric dispersion, were investigated in this study to determine their effect on the performance characteristics of tablets coated with a plasticized aqueous ethylcellulose dispersion (Surelease) in a fluid-bed equipment. Response surface methodology (RSM) was utilized to study the complex relationship between these process variables and selected response variables. Three response variables were considered, namely, rate of drug release from the “untreated” coated tablets and the “thermal-treated” coated tablets and microindentation hardness of the untreated coated tablets. A 12-point factorial experimental design was utilized, and three-dimensional (3-D) response surface plots were generated using a second-order polynomial model. The model provided information needed to predict optimal process conditions. Drug release from the coated tablets followed zero-order kinetics. Inlet-air temperature was found to be the most critical process variable for all the three response variables studied. A correlation was observed between the drug release rate and the microindentation hardness of the applied polymeric coat in the case of untreated coated tablets. The 3-D response surface plots indicated that lower rates of drug release from the coated tablets may be obtained by using high inlet-air temperature and low spray rate of the polymeric dispersion during coating.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018989717297
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