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Articles 21781 - 21810 of 24568
Full-Text Articles in Social and Behavioral Sciences
Contribution To The Theory Of Scarpland Development From Observations In Central Queensland, Australia, R. W. Young, R. A. Wray
Contribution To The Theory Of Scarpland Development From Observations In Central Queensland, Australia, R. W. Young, R. A. Wray
Faculty of Science - Papers (Archive)
Theories of scarpland geomorphology developed over the past century have been characterised by divergent conceptual frameworks and have been hindered by language barriers. Here, we review the main theories and assess them with reference to field evidence from central Queensland, Australia.
Thyroid Hormones And Their Effects: A New Perspective, A. J. Hulbert
Thyroid Hormones And Their Effects: A New Perspective, A. J. Hulbert
Faculty of Science - Papers (Archive)
The thyroid hormones are very hydrophobic and those that exhibit biological activity are 3',5',3,5-ltetraiodothyronine (T4), 3',5,3-l-triiodothyronine (T3), 3',5',3-l-triiodothyronine (rT3) and 3,5,-ldiiodothyronine (3,5-T2). At physiological pH, dissociation of the phenolic -OH group of these iodothyronines is an important determinant of their physical chemistry that impacts on their biological effects. When non-ionized these iodothyronines are strongly amphipathic. It is proposed that iodothyronines are normal constituents of biological membranes in vertebrates. In plasma of adult vertebrates, unbound T4 and T3 are regulated in the picomolar range whilst protein-bound T4 and T3 are maintained in the nanomolar range. The function of thyroid-hormone-binding plasma proteins …
Desiccation Tolerance Of Three Moss Species From Continental Antarctica, Sharon A. Robinson, J. Wasley, M. Popp, C. E. Lovelock
Desiccation Tolerance Of Three Moss Species From Continental Antarctica, Sharon A. Robinson, J. Wasley, M. Popp, C. E. Lovelock
Faculty of Science - Papers (Archive)
Tolerance of desiccation was examined in three species of moss, Grimmia antarctici Card., Ceratodon purpureus (Hedw.) Brid. and Bryum pseudotriquetrum (Hedw.) Gaertn., Meyer et Scherb. collected from two sites of contrasting water availability in the Windmill Islands, continental Antarctica. Physiological tolerance to desiccation was measured using chlorophyll fluorescence in plugs of moss during natural drying in the laboratory. Differences in relative water contents, rates of drying and the response of photosynthesis to desiccation were observed among the three species and between sites. Of the three species studied, G. antarctici showed the lowest capacity to sustain photosynthetic processes during desiccation, B. …
Tracing Beach Sand Provenance And Transport Using Foraminifera: Preliminary Examples From Northwest Europe And Southeast Australia, S. K. Haslett, Edward A. Bryant, R. H. Curr
Tracing Beach Sand Provenance And Transport Using Foraminifera: Preliminary Examples From Northwest Europe And Southeast Australia, S. K. Haslett, Edward A. Bryant, R. H. Curr
Faculty of Science - Papers (Archive)
Foraminifera are marine Sarcodine Protozoa that possess tests (shells) that are preservable in the fossil record. These tests may either be constructed using organically cemented detritus (agglutinating or arenaceous forms), or secreted using calcium carbonate (calcareous forms). Their ecology embraces planktonic and benthonic modes, although planktonic forms generally inhabit the open ocean and seldom live in coastal waters in any abundance, while benthonic foraminifera exist on substrates from abyssal plains to high intertidal areas. There are many species of foraminifera that are niche-specific, making them ideal for palaeoenvironmental analysis (Boersma, 1978; Brasier, 1980; Murray, 1991; Culver, 1993).
Comparing Species Of Bees For Controlled Pollination Of Helianthus Petiolaris In Field Cages, R. L. Wilson, C. A. Abel, M. E. Brothers
Comparing Species Of Bees For Controlled Pollination Of Helianthus Petiolaris In Field Cages, R. L. Wilson, C. A. Abel, M. E. Brothers
Journal of the Iowa Academy of Science: JIAS
Honey bees, Apis mellifera, have been used for several years to pollinate caged plant species maintained at the USDA-ARS North Central Regional Plant Introduction Station (NCRPIS), Ames, Iowa. Because maintaining large numbers of honey bees is expensive and time consuming, we began looking in 1995 for other pollinator species that can be easily managed and less expensive to maintain than A. mellifera. One species we tested was the hornfaced bee, Osmia cornifrons, a solitary bee imported from Japan in the late 1970s. We also tested a mixture of native bumblebees, Bombus bimaculatus and B. impatiens, which are native to the …
The Status Of The Blacknose Shiner (Notropis Heterolepis) Tn Iowa: A Preliminary Survey, Neil P. Bernstein, Michael Getting, Timothy Kamp, Stevenson Christain, Ryan Smith, Joseph Steele, Steven Steele
The Status Of The Blacknose Shiner (Notropis Heterolepis) Tn Iowa: A Preliminary Survey, Neil P. Bernstein, Michael Getting, Timothy Kamp, Stevenson Christain, Ryan Smith, Joseph Steele, Steven Steele
Journal of the Iowa Academy of Science: JIAS
During the last 45 years, the blacknose shiner (Notropis heterolepis) has been restricted to a three county area in northwestern Iowa. We surveyed locations where this siltation-intolerant species had been captured to update the status of the fish in the state. Streams were blocked with nets on both the upstream and downstream ends of sample areas, and fish were collected with a backpack electrofisher and seines. Lakes where the blacknose shiner had been found were also sampled. No blacknose shiners were found and several possible explanations are offered for their absence from historical sites.
Editorial Board & Iowa Academy Of Science Officers And Directors
Editorial Board & Iowa Academy Of Science Officers And Directors
Journal of the Iowa Academy of Science: JIAS
No abstract provided.
Distribution And Abundance Of Three Freshwater Mussel Species (B1valv1a: U Ntontdae) Correlated With Physical Habitat Characteristics In An Iowa Reservoir, J. R. Straka, J. A. Downing
Distribution And Abundance Of Three Freshwater Mussel Species (B1valv1a: U Ntontdae) Correlated With Physical Habitat Characteristics In An Iowa Reservoir, J. R. Straka, J. A. Downing
Journal of the Iowa Academy of Science: JIAS
A rapid drawdown (weeks) of a reservoir allowed us to determine the combined influence of water depth, maximum effective fetch, bottom slope, and substrate characteristics on abundance of three species of freshwater mussels. The three principal mussel species were significantly (PPyganodon grandis(Say) was most abundant on deeper shelves (ca. 3 m depth, slope 1 km), and sediment organic matter content was moderate (Lampsilis siliquoidea(Barnes), however, was most abundant in shallow water (Potamilus alatus(Say) had a more cosmopolitan depth distribution, but was found only on bottoms with low slope (Pyganodon grandiswas found to be negatively affected by increasing substrate organic matter …
Population Size Estimates For The Endangered Iowa Pleistocene Snail, Discus Macclintocki Baker, Tama K. Anderson
Population Size Estimates For The Endangered Iowa Pleistocene Snail, Discus Macclintocki Baker, Tama K. Anderson
Journal of the Iowa Academy of Science: JIAS
Discus macclintocki Baker, the Iowa Pleistocene snail, is a federally endangered species found only on algific talus slopes in northeastern Iowa and northwestern Illinois. Population size estimates for fourteen D. macclintocki populations in Iowa and Illinois ranged from 182 to 22,125 individuals. Estimates from the program CAPTURE as well as Bayesian estimation procedures gave similar results, although the Bayesian method allowed estimation of populations that could not be estimated with CAPTURE due to small sample sizes. A comparison of two methods of sampling, visual counts of quadrats and cover boards, showed that using cover boards resulted in much higher probabilities …
Editorial Board & Iowa Academy Of Science Officers And Directors
Editorial Board & Iowa Academy Of Science Officers And Directors
Journal of the Iowa Academy of Science: JIAS
No abstract provided.
Morphological Abnormalities In Illinois Cricket Frogs, Acris Crepitans, 1968-71, Robert H. Gray
Morphological Abnormalities In Illinois Cricket Frogs, Acris Crepitans, 1968-71, Robert H. Gray
Journal of the Iowa Academy of Science: JIAS
Reports of malformed amphibians have been increasing, including external deformities such as missing or extra arms and legs, missing eyes and mandibles, and internal abnormalities involving the bladder, digestive system, and testes. Natural phenomena such as limb amputations during predation attempts by other animals, parasitism, xenobiotic chemicals (herbicides, insecticides, fertilizers and others), and UV-B or other radiation (either directly or indirectly by triggering production of toxicants from nontoxic chemicals) have all been linked to amphibian abnormalities. From 1968-71, I studied the natural history, effective breeding size, and seasonal, annual, and geographic variation in color morph frequencies of cricket frogs (Acris …
Field Investigations Of Malformed Frogs In Minnesota 1993-97, Judy C. Helgen, Mark C. Gernes, Susan M. Kersten, Joel W. Chirhart, Jeff T. Canfield, Dorothy Bowers, Jon Haferman, Robert G. Mckinnell, David M. Hoppe
Field Investigations Of Malformed Frogs In Minnesota 1993-97, Judy C. Helgen, Mark C. Gernes, Susan M. Kersten, Joel W. Chirhart, Jeff T. Canfield, Dorothy Bowers, Jon Haferman, Robert G. Mckinnell, David M. Hoppe
Journal of the Iowa Academy of Science: JIAS
Reports of malformed frogs were made to the Minnesota Pollution Control Agency (MPCA) from different parts of Minnesota in 1993, 1995, 1996, and 1997 and one, nine, 190, and 172 reports were received, respectively. MPCA field crews and Drs. Hoppe and McKinnell documented malformed frog locations starting in 1993. By 1997, MPCA field crews documented malformed frogs at 62 locations in Minnesota, in 29 of 87 counties. Most malformations were in young metamorphs of Rana pipiens but they were observed also in R. clamitans, R. septentrionalis, R. sylvatica, Bufo americanus, and Hyla spp. Frequencies of malformations varied by time of …
Effects Of Pcb 126 And Ammonia, Alone And In Combination, On Green Frog (Rana Clamitans) And Leopard Frog (R. Pipiens) Hatching Success, Development, And Metamorphosis, Mariana Beatriz Jofre, Michele L. Rosenshield, William H. Karasov
Effects Of Pcb 126 And Ammonia, Alone And In Combination, On Green Frog (Rana Clamitans) And Leopard Frog (R. Pipiens) Hatching Success, Development, And Metamorphosis, Mariana Beatriz Jofre, Michele L. Rosenshield, William H. Karasov
Journal of the Iowa Academy of Science: JIAS
The Green Bay watershed in Wisconsin is polluted with polychlorinated biphenyls (PCBs), dioxin, heavy metals, ammonia, and over 100 organic contaminants. In this study we exposed embryos and larvae of two ranid species commonly occurring in the Green Bay ecosystem, the green frog (Rana clamitans) and the leopard frog (R. pipiens), to PCB 126 (3,3', 4,4', 5-Pentachlorobyphenil, nominal concentrations 0-50 μg/l, two control treatments: water plus 0.08% acetone as carrier for the PCB, water alone), unionized ammonia (0-2 mg/I), and mixtures of both contaminants. Exposure to PCB 126 did not cause significant mortality of embryos before hatching. However, exposure to …
The North American Reporting Center For Amphibian Malformations, Douglas H. Johnson, Suzanne C. Fowle, Jeffrey A. Jundt
The North American Reporting Center For Amphibian Malformations, Douglas H. Johnson, Suzanne C. Fowle, Jeffrey A. Jundt
Journal of the Iowa Academy of Science: JIAS
The North American Reporting Center for Amphibian Malformations was established to provide a conduit of information about, and a systematic data base on, malformed amphibians. This article describes the Reporting Center and the variety of features available at its Web site, presents an example of a summary analysis that can be conducted with its data, discusses caveats about the data, and makes recommendations about systematic surveys to better understand patterns and trends in the incidence of malformed amphibians.
Demographic And Reproductive Characteristics Of A Southern Illinois Population Of The Crayfish Frog, Rana Areolata, Michael Redmer
Demographic And Reproductive Characteristics Of A Southern Illinois Population Of The Crayfish Frog, Rana Areolata, Michael Redmer
Journal of the Iowa Academy of Science: JIAS
Demographic (snout-vent length, skeletochronologically estimated age) and reproductive (fecundity, ova size) characteristics were examined in Riina areolata from Williamson County, Illinois. Fifty-nine frogs (36 males, 23 females) were sampled from breeding choruses in March 1996. Hematoxylinophilic annular lines of arrested growth (LAG) were detected in the diaphyses of cross-sectioned phalanges of all sampled frogs. t-tests revealed that male age (mean = 3.53 yr) and female age (mean = 3.83 yr) were not significantly different, but male SVL (mean = 82.78 mm) was significantly smaller than that of females (mean = 89.61 mm). There were positive correlations between SVL and age …
Density-Dependent Effects On Microhabitat Selection And Activity Of Two Species Of Larval Ambystoma Salamanders, Jeanette M. Jaskula, Robert Brodman
Density-Dependent Effects On Microhabitat Selection And Activity Of Two Species Of Larval Ambystoma Salamanders, Jeanette M. Jaskula, Robert Brodman
Journal of the Iowa Academy of Science: JIAS
To be able to distinguish unnatural amphibian declines from natural population fluctuations we need a better understanding of the mechanisms that affect amphibian community structure. Larval pond-breeding salamanders exhibit density-dependent effects on population parameters, but little is known of the effect of density on behaviors that mediate interactions. Two species, Amby1toma tigrinum (tiger salamander) and A. laterale (blue-spotted salamander), were evaluated in laboratory aquaria for intraspecific and interspecific interactions that affect microhabitat selection and activity. Microhabitat selection was studied by partitioning containers into microhabitats that either contained or lacked refuges, and movement was recorded over a hexagonal grid to determine …
Frog And Toad Population Monitoring In Michigan, Lori G. Sargent
Frog And Toad Population Monitoring In Michigan, Lori G. Sargent
Journal of the Iowa Academy of Science: JIAS
A volunteer-based monitoring project for frog and toad populations in Michigan was initiated in 1996. The survey protocols developed by the North American Amphibian Monitoring Program (NAAMP) were used and modified to suit the needs of the Michigan project and because of the highly variable Michigan spring weather. The modifications include route establishment, recommended dates during which surveys are conducted, and a more specific definition of population indices. Development of the project included training workshops for volunteers.
Herpetofaunal Abundance And Distribution In Northern Minnesota: Contributions Of Ecological Land Units And Assessment Of Sampling Methodology, Gabrielle Yaunches, S. R. Winterstein, H. Campa Iii, B. J. Kernohan, J. B. Haufler
Herpetofaunal Abundance And Distribution In Northern Minnesota: Contributions Of Ecological Land Units And Assessment Of Sampling Methodology, Gabrielle Yaunches, S. R. Winterstein, H. Campa Iii, B. J. Kernohan, J. B. Haufler
Journal of the Iowa Academy of Science: JIAS
Herpetofaunal species distributions need to be understood and mapped using landscape descriptions that incorporate important habitat features and ecological processes. An ecosystem management effort in northern Minnesota is characterizing a landscape as a coarse filter for ecological communities. The coarse filter approach involves looking at communities in different successional stages and habitat types in a region (Haufler et al. 1996). Documenting distributions and abundances of herpetofauna using this coarse filter approach will allow data about these species to be incorporated in landscape planning efforts.
Conclusions Drawn From The Malformity And Disease Session, Midwest Declining Amphibians Conference, 1998, Michael J. Lannoo
Conclusions Drawn From The Malformity And Disease Session, Midwest Declining Amphibians Conference, 1998, Michael J. Lannoo
Journal of the Iowa Academy of Science: JIAS
While the general problem of amphibian declines is well known, no issue recently has engendered as much concern by the public as amphibian malformities (Ouellet et al. 1996, Tietge 1996, Gray 1998, Helgen et al. 1998a and 1998b, D. Johnson 1998, T. Johnson 1998, Meteyer and Converse 1998). As a result, Gary Casper, Chris Phillips and I decided to assemble this symposium. The session was open to anyone who wished to participate. Nineteen papers were presented (there was one cancellation) and a panel discussion followed. I will organize this summary of, and conclusions drawn from, our symposium into two sections: …
Book Review: Iowa's Geological Past: Three Billion Years Of Change, Raymond R. Anderson
Book Review: Iowa's Geological Past: Three Billion Years Of Change, Raymond R. Anderson
Journal of the Iowa Academy of Science: JIAS
Iowa's Geological Past: Three Billion Years of Change. Wayne Anderson, 1998. University of Iowa Press, Iowa City IA. xii + 424 pages. ISBN 0-87745-639-9, ISBN 0-87745-640-2 (pbk.).
Wayne Anderson, born in geode country in southeast Iowa, earned his Bachelors, Masters, and Ph.D. at the University of Iowa (writing a thesis and dissertation on Iowa geologic topics). He will complete a 37-year career teaching geology at the University of Northern Iowa with his retirement in the Spring of 2000. His research activities and the work of his students have added greatly to our understanding of the geology of eastern Iowa. In …
Cover - Table Of Contents
Journal of the Iowa Academy of Science: JIAS
No abstract provided.
Corn (Zea Mays L.) Yield Response To Nitrogen Fertilizer In Conventional And Alternative Rotations, M. M. Harbur, M. Ghaffarzadeh, R. M. Cruse
Corn (Zea Mays L.) Yield Response To Nitrogen Fertilizer In Conventional And Alternative Rotations, M. M. Harbur, M. Ghaffarzadeh, R. M. Cruse
Journal of the Iowa Academy of Science: JIAS
Nitrogen (N) fertilization recommendations are not available for corn in rotation with small grains or forages despite the possibility that the N response may differ from that of more conventional corn-soybean rotations. Rotations of corn with soybean (CS), corn with soybean and oat (CSO) and corn with soybean and an oat/berseem clover intercrop (CSOB) were established in 1991 and studied from 1993 through 1998 to determine the optimal N fertilization level for corn produced in each rotation. Corn in each rotation received NH4N03 applied at the rates of 0, 56, 112, or 168 kg N ha-1. Significant differences …
Checklist Of Instructions For Authors
Checklist Of Instructions For Authors
Journal of the Iowa Academy of Science: JIAS
No abstract provided.
Limits To Ice Thickness In Iowa During The Late Wisconsinan, Eric C. Brevik
Limits To Ice Thickness In Iowa During The Late Wisconsinan, Eric C. Brevik
Journal of the Iowa Academy of Science: JIAS
Minimum and maximum limits to Des Moines Lobe ice thickness in Iowa during the Late Wisconsinan glaciation are calculated. These limits are based on minimum and maximum ice thickness calculations for the Des Moines Lobe in eastern North Dakota using crustal depression indicated by Lake Agassiz strandlines. Minimum and maximum basal shear stresses for the Des Moines Lobe are calculated by projecting a flow line from the terminus of the Des Moines Lobe back up-ice to the study site in northeastern North Dakota. Ice thickness in Iowa is then calculated with a method that uses the basal shear stress values. …
Cover - Investigating Amphibian Declines: Proceedings Of The 1998 Declining Amphibians Conference
Cover - Investigating Amphibian Declines: Proceedings Of The 1998 Declining Amphibians Conference
Journal of the Iowa Academy of Science: JIAS
No abstract provided.
Interactive Effects Of Anthropogenic, Environmental, And Biotic Stressors On Multiple Endpoints In Hyla Chrysoscelis, Carol A. Britson, Stephen T. Threlkeld
Interactive Effects Of Anthropogenic, Environmental, And Biotic Stressors On Multiple Endpoints In Hyla Chrysoscelis, Carol A. Britson, Stephen T. Threlkeld
Journal of the Iowa Academy of Science: JIAS
Multiple stressors have been proposed as causative agents for declining populations and increased incidence of malformations in amphibians although few studies have examined possible interactions among these stressors. We measured interactive effects of UV radiation, three chemicals, and interspecific competition (with Rana 1phenocephala) on multiple endpoints in Hyla chrysoscelis using a center point- and chemical-free control-enhanced 24 factorial design. UV radiation was transmitted or filtered using OP-4 or OP-3 acrylite filters installed above 72, 500-liter mesocosms on 16 May 1997. Methyl mercury, chlorpyrifos, and atrazine were applied at levels of 0, 10, 50, and 100 % of 400 ppb, …