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2004

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Articles 3361 - 3390 of 3408

Full-Text Articles in Life Sciences

Crop And Soil Productivity Response To Corn Residue Removal: A Literature Review, Wallace Wilhelm, J.M.F. Johnson, J. L. Hatfield, W.B. Voorhees, D.R. Linden Jan 2004

Crop And Soil Productivity Response To Corn Residue Removal: A Literature Review, Wallace Wilhelm, J.M.F. Johnson, J. L. Hatfield, W.B. Voorhees, D.R. Linden

Agronomy & Horticulture -- Faculty Publications

Society is facing three related issues: over-reliance on imported fuel, increasing levels of greenhouse gases in the atmosphere, and producing sufficient food for a growing world population. The U.S. Department of Energy and private enterprise are developing technology necessary to use high-cellulose feedstock, such as crop residues, for ethanol production. Corn (Zea mays L.) residue can provide about 1.7 times more C than barley (Hordeum vulgare L.), oat (Avena sativa L.), sorghum [Sorghum bicolor (L.) Moench], soybean [Glycine max L.) Merr.], sunflower (Helianthus annuus L.), and wheat (Triticum aestivum L.) residues based on production levels. Removal of crop ...


Changes In Nitrogen Use Efficiency And Soil Quality After Five Years Of Managing For High Yield Corn And Soybean, Timothy J. Arkebauer, Achim R. Dobermann, Kenneth G. Cassman, Rhae A. Drijber, J. Lindquist, James E. Specht, Daniel T. Walters, Haishun Yang Jan 2004

Changes In Nitrogen Use Efficiency And Soil Quality After Five Years Of Managing For High Yield Corn And Soybean, Timothy J. Arkebauer, Achim R. Dobermann, Kenneth G. Cassman, Rhae A. Drijber, J. Lindquist, James E. Specht, Daniel T. Walters, Haishun Yang

Agronomy & Horticulture -- Faculty Publications

Average corn grain yields in the USA have increased linearly at a rate of 1.7 bu/acre over the past 35 years with a national yield average of 140 bu/acre. Corn yield contest winners and simulation models, however, indicate there is ~100 bu/a in exploitable corn yield gap. Four years (1999-2002) of plant development, grain yield and nutrient uptake were compared in intensive irrigated maize systems representing (a) recommended best management practices for a yield goal of 200 bu/acre (M1) and (b) intensive management aiming at a yield goal of 300 bu/acre (M2). For each ...


Factors Affecting The Realized Niche Of Common Sunflower (Helianthus Annuus) In Ridge-Tillage Corn, Michael G. Burton, David A. Mortensen, David B. Marx, John L. Lindquist Jan 2004

Factors Affecting The Realized Niche Of Common Sunflower (Helianthus Annuus) In Ridge-Tillage Corn, Michael G. Burton, David A. Mortensen, David B. Marx, John L. Lindquist

Agronomy & Horticulture -- Faculty Publications

Because soil characteristics and weed densities vary within agricultural landscapes, determining which subfield areas are most favorable to weed species may aid in their management. Field and greenhouse studies were conducted to determine whether subfield environments characterized by higher soil organic carbon (SOC), or ridge vs. furrow microsites, affect common sunflower seed germination after winter burial, seedling emergence, or the control afforded by a preemergence herbicide in a ridge-tillage corn production system. Among seeds buried in situ during winter months and germinated in the laboratory, no differences in common sunflower seed germination or mortality were detected between high-SOC (1.8 ...


Glyphosate Efficacy On Velvetleaf Varies With Application Time Of Day, Aaron L. Waltz, Alex R. Martin, Fred W. Roeth, John L. Lindquist Jan 2004

Glyphosate Efficacy On Velvetleaf Varies With Application Time Of Day, Aaron L. Waltz, Alex R. Martin, Fred W. Roeth, John L. Lindquist

Agronomy & Horticulture -- Faculty Publications

Field and growth chamber experiments determined the efficacy of temporal glyphosate applications on velvetleaf. Glyphosate was applied post-emergence to velvetleaf periodically before and during light and after dark. In 1999, glyphosate at 840 g ae/ha applied before sunrise and after midday provided 54 and 100% velvetleaf control, respectively. In 2000, glyphosate at 840 g/ha applied before sunrise, midday, and after sunset provided 69, 100, and 37% velvetleaf control, respectively. In the growth chamber, glyphosate at 840 g/ha applied before or after light reduced velvetleaf biomass 15 to 20% or 32 to 47%, respectively, and reduced velvetleaf height ...


Windbreaks, Robert J. Rouse, Laurie Hodges Jan 2004

Windbreaks, Robert J. Rouse, Laurie Hodges

Agronomy & Horticulture -- Faculty Publications

Windbreaks are an important and often overlooked component of a plasticulture system. They provide benefits regardless of where you farm or what crops you are raising. When wind protection is included in a plasticulture production system, crops benefit from less wind stress and an improved microclimate for growth and development. There is less crop injury due to soil abrasion or wind-whipping of plants, less extreme soil temperature fluctuations, and improved soil warming. Wind protection often results in earlier yields of higher-quality crops.


Cytokinin-Induced Metabolic Redirection, Uyen Bao, Gautam Sarath Jan 2004

Cytokinin-Induced Metabolic Redirection, Uyen Bao, Gautam Sarath

Publications from USDA-ARS / UNL Faculty

Cytokinins are key triggers for the growth and differentiation of plant cells. We have generated a transgenic line of Arabidopsis that carries a rice hemoglobin promoter fused to GUS. Earlier research has indicated that this promoter is very responsive to cytokinins. We are utilizing this line to understand the global and local responses of gene-expression to exogenously applied cytokinins. In addition, we have cloned and have started to characterize two gene products of as yet unknown functions that are dramatically up-regulated or down-regulated in response to cytokinins. Data from microarray analyses will be discussed in relation to potential metabolic redirection ...


Carbon Dioxide Dynamics During A Growing Season In Midwestern Cropping Systems, J. H. Prueger, J. L. Hatfield, T. B. Parkin, W.P. Kustas, T. C. Kaspar Jan 2004

Carbon Dioxide Dynamics During A Growing Season In Midwestern Cropping Systems, J. H. Prueger, J. L. Hatfield, T. B. Parkin, W.P. Kustas, T. C. Kaspar

Publications from USDA-ARS / UNL Faculty

Daily and seasonal CO2-exchange dynamics between the boundary layer and biosphere is important to understanding Net Ecosystem Exchange of terrestrial ecosystems. Spatial and temporal variations of CO2 fluxes across midwestern cropping systems have not been well documented. This study was designed to monitor and evaluate spatial and temporal dynamics of CO2 exchange across a watershed region for typical production fields of corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] in the Midwest by quantifying the above-canopy, within-canopy, and soil components of C balance for this cropping system. An energy-balance approach using eddy covariance was ...


Water Quality And The Grazing Animal, R. K. Hubbard, G. L. Newton, G. M. Hill Jan 2004

Water Quality And The Grazing Animal, R. K. Hubbard, G. L. Newton, G. M. Hill

Publications from USDA-ARS / UNL Faculty

Grazing animals and pasture production can affect water quality both positively and negatively. Good management practices for forage production protect the soil surface from erosion compared with conventionally produced crops. Grazing animals and pasture production can negatively affect water quality through erosion and sediment transport into surface waters, through nutrients from urine and feces dropped by the animals and fertility practices associated with production of high-quality pasture, and through pathogens from the wastes. Erosion and sediment transport is primarily associated with high-density stocking and/ or poor forage stands. The two nutrients of primary concern relating to animal production are N ...


Neuroplasticity And Functional Recovery: Training Models And Compensatory Strategies In Music Therapy, Felicity Baker, Edward A. Roth Jan 2004

Neuroplasticity And Functional Recovery: Training Models And Compensatory Strategies In Music Therapy, Felicity Baker, Edward A. Roth

BRAIN Lab Research

New research developments in the recovery of function following neurological trauma as well as basic and applied research relevant to music perception and production, seem to point to the suggestion that specific music therapy interventions that directly address the restoration of function as opposed to developing compensatory mechanisms, in certain circumstances, may now be a more appropriate treatment approach. We will address the issue of appropriate timing for the introduction of each strategy and discuss potential outcomes of each approach. As one might imagine, much of this research is published in the neurological journals, which music therapists may not regularly ...


Openness In The Face Of Systemic Constraints On Science, Public Participation, And The Western Australian Regional Forest Agreement, Martin Brueckner Jan 2004

Openness In The Face Of Systemic Constraints On Science, Public Participation, And The Western Australian Regional Forest Agreement, Martin Brueckner

Theses: Doctorates and Masters

The aim of this thesis is to explore the role of science and public participation in environmental policy-making processes in Australia. To this end, I analyse the Western Australian Regional Forest Agreement (RFA) process, a recent Australian Federal Government initiative designed to resolve a longstanding dispute over native forest use and management. Theoretically underpinned by an open systems approach, the thesis employs a case study method for the analysis of the RFA process, using data from three distinct sources; interviews, RFA-related literature, and media content. The analysis of the RFA occurs against the historical background to this policy process and ...


Terrestrial Isopods (Crustacea: Oniscidea) And Biogeographical Patterns From South-Western Australia, Simon L. Judd Jan 2004

Terrestrial Isopods (Crustacea: Oniscidea) And Biogeographical Patterns From South-Western Australia, Simon L. Judd

Theses: Doctorates and Masters

This thesis examines terrestrial isopod (Crustacea: Oniscidea) diversity and biogeography from south-western Australia, a region already recognised for the exceptional high biodiversity and concentrations of endemic species. A taxonomic investigation of isopods in the Western Australian Museum and material collected systematically as part of this study revealed seventy taxa, sixty of which were considered native species. The thesis provides a comprehensive review of regional taxonomic history and includes a key, complete with a set of forty characters states and taxa, illustrated by a number of photographic plates that are designed for use by specialists and non-specialists alike. Prior to this ...


In Vitro Propagation Of Some Western Australian Seagrasses, Julia Wilson Jan 2004

In Vitro Propagation Of Some Western Australian Seagrasses, Julia Wilson

Theses: Doctorates and Masters

The development of a successful protocol for micropropagating seagrass provides a valuable tool for seagrass-restoration programs and a facility to study their biology (especially their physiology). This work reports on some of the culture requirements of some seagrasses that are commonly found in Western Australia: Posidonia coriacea, P. sinuosa, P. australis and Halophila ovalis. The protocol developed for H. ovalis allows very rapid multiplication and sustainable growth of cultures while the protocol developed for Posidonia requires further development. The culture of Posidonia cariacea proved to be problematic however experimental media that provided insights into its culture conditions. The carbohydrate source ...


The Use Of Proline To Determine Salt Tolerance In Eucalyptus Species And Clones, Andrew J. Woodward Jan 2004

The Use Of Proline To Determine Salt Tolerance In Eucalyptus Species And Clones, Andrew J. Woodward

Theses: Doctorates and Masters

There have been a number of studies that have examined the Eucalyptus spp. for their salt and waterlogging tolerance: but they have done so using conventional methods. A wide range of plants are known to produce greater amounts of proline when stressed, be it salt, temperature, 'drought or several other types of stress. This study looked at production of proline in salt stressed eucalypts to determine whether it can be used to differentiate between individuals andspecies. A range of Eucalyptus species and salt tolerant clones of E. camaldulensis were grown to investigate their proline response to salt stress.


The Role Of Farm Dams As Refugia For Aquatic Invertebrates In A Salinised Landscape, South Western Australia, Jean-Michel Benier Jan 2004

The Role Of Farm Dams As Refugia For Aquatic Invertebrates In A Salinised Landscape, South Western Australia, Jean-Michel Benier

Theses: Doctorates and Masters

In a salinised landscape farm dams may represent the last truly freshwater surface resource, and therefore provide refuge habitats for the biota of wetlands affected by increasing salinity. One wetland threatened by increased salinity in south-west Western Australia is Lake Toolibin. It is listed as a Wetland of International Importance under the Ramsar Convention in recognition of its high conservation value, and remediation actions to halt (and possibly reverse) further increases in salinity are being undertaken at this wetland. Farm dams act as aquatic refugia if they convey resistance and/or resilience to the biotic communities of a disturbed habitat ...


Environmental Correlates And Associations Of Tuart (Eucalyptus Gomphocephala) Decline, Todd A. Edwards Jan 2004

Environmental Correlates And Associations Of Tuart (Eucalyptus Gomphocephala) Decline, Todd A. Edwards

Theses: Doctorates and Masters

Tuart (Eucalyptus gomphocephala DC.) is an ecologically and culturally important tree species that grows across a narrow 400 km long coastal belt, from the Sabrina River south of Perth, to Jurien Bay in the north. Unfortunately, Tuart is also a species under considerable threat due to clearing, lack of recruitment and canopy decline. Canopy decline is of particular concern, being increasingly reported throughout the Tuart distribution. Despite this, previous studies of Tuart have generally been limited to localised canopy decline events. This two-phased study firstly involved an assessment of Tuart canopy condition at 46 sites across the species distribution. At ...


Investigation Of The Replacement Of Margaret River Hairy Marron Cherax Tenuimanus (Smith) By Smooth Marron C. Cainii Austin, John J. Bunn Jan 2004

Investigation Of The Replacement Of Margaret River Hairy Marron Cherax Tenuimanus (Smith) By Smooth Marron C. Cainii Austin, John J. Bunn

Theses: Doctorates and Masters

The Margaret River hairy marron, Cherax tenuimanus (Smith, 1912) (Decapoda: Parastacidae) is critically endangered due to the introduction of the widespread marron, C. cainii Austin, 2002. This project investigates the rapid replacement of C. tenuimanus with studies important to its conservation. The ability to identify correctly in the field C. tenuimanuss, C. cainii and hybrids was investigated by linking morphology and marker allozyme loci. C. tenuimanus was readily identified in the field and errors were conservative; no genetically identified hybrids or C. cainii were field identified as C. tenuimauus during tissue samples collection. A prototype field identification guide has been ...


Conserving Reptiles And Frogs In The Forests Of New South Wales, David A. Newell, Ross L. Goldingay Jan 2004

Conserving Reptiles And Frogs In The Forests Of New South Wales, David A. Newell, Ross L. Goldingay

School of Environment, Science and Engineering Papers

No abstract provided.


Heavy Metals In Mangroves: Methodology, Monitoring And Management, Peter Saenger, David Mcconchie Jan 2004

Heavy Metals In Mangroves: Methodology, Monitoring And Management, Peter Saenger, David Mcconchie

School of Environment, Science and Engineering Papers

Mangroves occur widely throughout Australia and, at some sites, are exposed to elevated heavy metal loads. The value of mangrove communities, and particularly of mangrove forest sediments, as a buffer between potential sources of metalliferous pollutants and marine ecosystems has been noted previously (Harbison, 1981, 1986; Saenger et al., 1991). How mangroves respond to the metal load in their environment remains largely unknown. Some work on the response of mangrove seedlings to heavy metal exposure (Montgomery and Price, 1979; Peterson et al., 1979; Walsh et al., 1979; Thomas and Ong, 1984; Chiu et al., 1995; Chen et al., 1995; Wong ...


Plant Surrogacy: An Evaluation Of Its Use And Application In The Effort To Conserve Ground Dwelling Invertebrates, Kerry Leigh Ironside Jan 2004

Plant Surrogacy: An Evaluation Of Its Use And Application In The Effort To Conserve Ground Dwelling Invertebrates, Kerry Leigh Ironside

Theses : Honours

A study conducted in the Ridges State Forest, Yanchep was designed to investigate the relationship between plant species richness, vegetation association and ground dwelling invertebrate species richness. Four plant communities were sampled at two scales of measurement. Two treatments were located in woodland and two in heath. Within each vegetation association, plant communities that were representative of both high and low species richness were selected. Three invertebrate orders, Araneae, Coleoptera and Araneae were sorted to morphospecies level. Ordinal richness was also investigated. Two-way ANOVAs indicated that there was no relationship between plant species richness, vegetation association· or the interaction between ...


Banksia Woodland Resilience To Groundwater Drawdown On The Gnangara Mound, Llewellyn Broun Jan 2004

Banksia Woodland Resilience To Groundwater Drawdown On The Gnangara Mound, Llewellyn Broun

Theses : Honours

Water is considered to be the major limiting resource to plant growth and survival in regions with a Mediterranean-type climate, particularly during dry summer periods when low water potentials develop (Poole et al., 1981; Miller et al., 1983-84; Mooney and Miller, 1985; Stock et al., 1992). The Swan Coastal Plain is situated within this climatic region and interactions between the climate, soil and geology has an important bearing on the water requirements of the associated Banksia woodlands (Dodd and Heddle, 1989). The assessment of the condition of any vegetative community and in this case, the resilience of Banksia woodlands to ...


Seasonal Effects On Diet Of Two Arid Zone Dasyurids, Dasycercus Cristicauda And Ningaui Ridei (Dasyuridae, Marsupialia), Leisa Turner Jan 2004

Seasonal Effects On Diet Of Two Arid Zone Dasyurids, Dasycercus Cristicauda And Ningaui Ridei (Dasyuridae, Marsupialia), Leisa Turner

Theses : Honours

Seasonal fluctuations in rainfall and food availability are thought to change populations of arid zone mammals dramatically over time. Competition between similar species for limited food resources is believed to be a major factor in the evolution and maintenance of population assemblages. Animals foraging in arid regions must be responsive to the unreliable distribution of nutrients and food resources to ensure the survival of viable populations. Adaptive physiological traits and behavioural mechanisms of arid zone animals allow them to survive extreme conditions and the ability to switch between prey species in adverse conditions is an advantageous strategy. This study was ...


Effects Of Temporary Par Reduction On The Seagrass Amphibolis Griffithii (Black) Den Hartog, Paul R. Mackey Jan 2004

Effects Of Temporary Par Reduction On The Seagrass Amphibolis Griffithii (Black) Den Hartog, Paul R. Mackey

Theses : Honours

Declines in seagrass health and distribution are commonly caused through human induced reductions in the availability of photosynthetically active radiation (PAR). These reductions can result from a variety of human-induced perturbations, including channel dredging. The impetus for the research was driven by the broad-scale degradation of the ecologically important southern-Australian endemic seagrass Amphibolis griffithii (Black) den Hartog in Champion Bay, Geraldton, Western Australia. The study investigated the affects of reduced PAR on A. griffithii and identified responses that may be useful in developing management triggers to minimise the impact of PAR limitation events. The study was carried out during late ...


Imagery In Sentence Comprehension: An Fmri Study, Marcel Just, Sharlene Newman, Timothy Keller, Alice Mceleney, Patricia Carpenter Dec 2003

Imagery In Sentence Comprehension: An Fmri Study, Marcel Just, Sharlene Newman, Timothy Keller, Alice Mceleney, Patricia Carpenter

Marcel Adam Just

No abstract provided.


How The Brain Processes Causal Inferences In Text: A Theoretical Account Of Generation And Integration Component Processes Utilizing Both Cerebral Hemispheres, Robert Mason, Marcel Just Dec 2003

How The Brain Processes Causal Inferences In Text: A Theoretical Account Of Generation And Integration Component Processes Utilizing Both Cerebral Hemispheres, Robert Mason, Marcel Just

Marcel Adam Just

No abstract provided.


Human Genetic Variation And Health: New Assessment Approaches Based On Ethnogenetic Layering, Fatimah Linda Collier Jackson Dec 2003

Human Genetic Variation And Health: New Assessment Approaches Based On Ethnogenetic Layering, Fatimah Linda Collier Jackson

Fatimah Linda Collier Jackson

Human genetic variation is often biologically relevant, particularly when it influences (or is influenced by) health outcomes. For example, human genetic variation can modulate disease aetiology as in the case of
homozygous beta sickle gene (βS/βS or sickle cell) pathology. Conversely, health outcomes, such as the frequency and duration of homozygous sickle cell pathology, can change affected group gene frequencies by selectively targeting and culling specific genotypes in a group, such as clinically more severe βS Bantu/βS Bantu versions of the βS gene, thereby changing future patterns of genetic variation in this gene.



Insects Raise Some Galling Questions, Warren G. Abrahamson Ii Dec 2003

Insects Raise Some Galling Questions, Warren G. Abrahamson Ii

Warren G. Abrahamson, II

No abstract provided.


Learning To Decode Cognitive States From Brain Images, Tom M. Mitchell, Rebecca Hutchinson, Radu S. Niculescu, Francisco Pereira, Xuerui Wang, Marcel Adam Just, Sharlene D. Newman Dec 2003

Learning To Decode Cognitive States From Brain Images, Tom M. Mitchell, Rebecca Hutchinson, Radu S. Niculescu, Francisco Pereira, Xuerui Wang, Marcel Adam Just, Sharlene D. Newman

Marcel Adam Just

No abstract provided.


Neurosteroids: Endogenous Modulators Of Seizure Susceptibility, Michael A. Rogawski, Doodipala S. Reddy Dec 2003

Neurosteroids: Endogenous Modulators Of Seizure Susceptibility, Michael A. Rogawski, Doodipala S. Reddy

Michael A. Rogawski

No abstract provided.


Classification And Successional Changes Of Mixed-Oak Forests At The Mohn Mill Area, Pennsylvania, Warren G. Abrahamson Ii, A.C. Gohn Dec 2003

Classification And Successional Changes Of Mixed-Oak Forests At The Mohn Mill Area, Pennsylvania, Warren G. Abrahamson Ii, A.C. Gohn

Warren G. Abrahamson, II

No abstract provided.


Further Additions To The Bibliography Of Alfred Russel Wallace (1823-1913), Charles H. Smith Dec 2003

Further Additions To The Bibliography Of Alfred Russel Wallace (1823-1913), Charles H. Smith

Charles Kay Smith

No abstract provided.