3,481 research outputs found
Using flow gauges to determine stem and root conductance in hybrid poplars.
Non-Peer ReviewedA study was conducted using sap flow gauges to determine stem and root conductance in hybrid poplars at two sites near Swift Current, Saskatchewan. At the Rushlake site, sap flow rates were compared between CanAm and Walker poplars using Dynamax (Model SGA-10) stem flow gauges. The primary objective was to determine if the difference in susceptibility to midsummer terminal shoot dieback in Walker and CanAm poplar clones could be attributed to leaf-specific conductance. Walker poplars appear to be well-suited to mesic sites and, under good soil moisture conditions, perform better than CanAm . However, they are susceptible to mid-season terminal shoot dieback, while CanAm poplars do not seem to be as susceptible. We suspect that this is primarily attributable to a greater leaf-specific conductance (LSC) of CanAm poplars. As a tertiary cause, perhaps CanAm poplars achieve a more complete stomatal closure during periods of extended vapor pressure deficits. The gauges were mounted at the distal ends (where the shoot diameter is about 10 mm) of actively growing branches near the crown of each tree. For a period of 14 days, the sap flow rates of each tree were measured. Preliminary results indicate that CanAms did indeed have a greater LSC and showed higher stem flow rates than Walker poplars. Under the study conditions at the Rushlake site, air temperatures were not of sufficient magnitude to determine differences in leaf stomatal closure between the CanAm and Walker trees. The LSC characteristics, however, would have benefited the CanAm poplars in functioning under extended vapor pressure deficits. A secondary objective was to determine if
differences in root conductances of poplars subjected to varying saline conditions were possible to measure using sap flow gauges. Although great care must be taken during gauge installation on tree roots, we found it is possible to measure root sap conductance on trees subjected to varying levels of salinity
Using flow gauges to determine leaf specific conductance in hybrid poplars under mesic and xeric conditions
Non-Peer ReviewedA study was conducted using sap flow gauges to determine leaf specific conductance (LSC) in hybrid poplars in an environmentally-controlled greenhouse at Swift Current, Saskatchewan. Sap flow rates were compared between CanAm and Walker poplar clones using stem flow gauges. The primary objectives were to verify differences in LSC observed between the clones under moist field conditions in a previous study and to compare the responses in sap flow and LSC within these trees as imposed soil conditions changed from moist to dry. Walker poplars appear to be well-suited to mesic sites, and, under ample soil moisture, perform better than CanAms. However, they are susceptible to mid-season terminal shoot dieback, while
CanAm poplars do not seem to be as susceptible. We suspect that this is primarily attributable to a greater LSC of CanAm poplars and possibly achieving better stomatal responses during periods of extended vapor pressure deficits. The gauges were mounted near the base of each tree. Following gauge installation, the trees were watered to field capacity. No additional water was added during the course of the test. Sap flow, leaf water potentials and tree conditions were monitored for 17 days as the soil conditions evolved from moist to dry. Results indicate that the CanAms displayed a greater LSC under moist as well as dry conditions compared to the Walkers. Throughout the testing period, CanAm mid-day leaf water potentials were slightly more negative than for the Walker poplars. Although CanAm poplars appear to be less water efficient than Walkers, they are better able to function and survive during periods of extended vapour pressure deficits
26Mg target for nuclear astrophysics measurements
Two nuclear reactions of astrophysical interest, 26Mg(3He,d)27Al and 26Mg(d,p)27Mg, were measured for extraction of the Asymptotic Normalization Coefficients. Investigation of the target composition is presented, as well as the effects that showed up during analysis of the in-beam data obtained on CANAM accelerators in the Nuclear Physics Institute of the Czech Academy of Sciences (NPI CAS)
Seasonality of global and Arctic black carbon processes in the Arctic Monitoring and Assessment Programme models
This study quantifies black carbon (BC) processes in three global climate models and one chemistry transport model, with focus on the seasonality of BC transport, emissions, wet and dry deposition in the Arctic. In the models, transport of BC to the Arctic from lower latitudes is the major BC source for this region. Arctic emissions are very small. All models simulated a similar annual cycle of BC transport from lower latitudes to the Arctic, with maximum transport occurring in July. Substantial differences were found in simulated BC burdens and vertical distributions, with Canadian Atmospheric Global Climate Model (CanAM) (Norwegian Earth System Model, NorESM) producing the strongest (weakest) seasonal cycle. CanAM also has the shortest annual mean residence time for BC in the Arctic followed by Swedish Meteorological and Hydrological Institute Multiscale Atmospheric Transport and Chemistry model, Community Earth System Model, and NorESM. Overall, considerable differences in wet deposition efficiencies in the models exist and are a leading cause of differences in simulated BC burdens. Results from model sensitivity experiments indicate that convective scavenging outside the Arctic reduces the mean altitude of BC residing in the Arctic, making it more susceptible to scavenging by stratiform (layer) clouds in the Arctic. Consequently, scavenging of BC in convective clouds outside the Arctic acts to substantially increase the overall efficiency of BC wet deposition in the Arctic, which leads to low BC burdens and a more pronounced seasonal cycle compared to simulations without convective BC scavenging. In contrast, the simulated seasonality of BC concentrations in the upper troposphere is only weakly influenced by wet deposition in stratiform clouds, whereas lower tropospheric concentrations are highly sensitive.Key PointsSeasonal variations of black carbon (BC) mass budgets in the Arctic are simulatedGood agreement in simulated annual mean transport of BC to the Arctic in modelsConvective wet removal is important for differences in modeled BC concentrationPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/133539/1/jgrd53064-sup-0001-SI.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/133539/2/jgrd53064.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/133539/3/jgrd53064_am.pd
White-Rot Fungi as Pretreatment Agents for Wood Destined for Biofuel Applications
Efficient and economical conversion of lignocellulosic biomass to biofuels is often hampered by the chemical recalcitrance of the material. Inexpensive and environmentally-friendly pretreatment processes are therefore desirable in order to lower the cost of biofuel production and minimize negative environmental impacts. To that end, we have explored the use of a naturally occurring white-rot fungus, Trametes versicolor, as a direct pretreatment agent for hardwood destined for biofuel applications. Specifically, we examined the pretreatment effects on the hardwood mixture after treatment with the wild-type strain of T. versicolor (52J) compared with those from a cellobiose dehydrogenase (CDH)-deficient strain (m4D) , to examine how a lack of CDH affects wood pretreatment. The effects of each strain of T. versicolor on the lignocellulose chemistry within the wood were examined after 12 weeks of incubation, as well as the physicochemical properties (pellet strength and energy content). At the laboratory scale, pretreatment with the mutant strain showed altered lignin structure and improved sugar yields, while the wild-type strain led to substantially increased pellet strength without impeding the overall energy content of the pellets. However, at the demonstration scale (150 L), the wild-type strain did not alter pellet strength, despite similar lignin extraction characteristics, glucose content, and energy content when compared to the laboratory scale. Therefore, further research will need to be conducted at the laboratory and demonstration scales to investigate how this fungus alters the structure of lignocellulose at the biochemical level (e.g., transcriptomic analysis), and how fungal pretreatment may affect other biofuel technologies, such as biomass gasification
Technological discontinuities, outsiders and social capital: a case study from Formula 1
Purpose â The purpose of this paper is to examine how and why outsiders, rather than incumbents, are able to take advantage of technological discontinuities. Design/ methodology/approach â The paper employs a case study of a single innovation that transformed the technology of Formula 1 motor racing. Findings â The findings show how social capital made up of âweak tiesâ in the form of informal personal networks, enabled an outsider to successfully make the leap to a new technological regime. Practical implications â The findings show that where new product development involves a shift to new technologies, social capital can have an important part to play. Originality/value â It is widely accepted that radical innovations are often competence destroying, making it difficult for incumbents to make the transition to a new technology. The findings show how the social capital of outsiders can place them at a particular advantage in utilizing new technologies
Carnivore Diet Identification Through Scat and Genetic Analysis in Namibia, Africa
Worldwide the cheetah population is declining making them Africaâs most endangered large cat. Namibia, Africa currently has the largest population of cheetahs in the world. During the summer of 2014, I did scat analysis of carnivores on the property of the Cheetah Conservation Fund (CCF) in Namibia in order to better understand the predators that compete with the cheetah and how the ecosystem works as a whole. I worked at CCF for nine weeks to analyze the diets of carnivores in the area through genetic and scat analysis. Analyzing carnivore feces would ultimately identify the diet of various carnivores in the area. One hundred and eight carnivore scat samples were analyzed including jackal, hyena, genet, serval, leopard, african wildcat, caracal, civet, aardwolf and cheetah samples. This information would help CCF understand how the entire ecosystem interacts and aid them in their efforts to manage and protect the wild cheetah. DNA was extracted from each scat sample to determine the species each sample came from. The DNA was then amplified using polymerase chain reaction. Ultimately, the sequences were compared to a genome reference database and the species were determined by sequence similarity. The scat samples were then washed and the contents were analyzed microscopically and macroscopically. Microscopic analysis involved burning hairs to create imprints and looking at the patterns underneath a microscope. My results revealed that the cheetahs are primarily competing with leopards for their prey. When CCF releases cheetahs back into the wild they will now be able to take my findings into consideration to locate the best release site
An Assessment of Transformation Protocols of Trametes versicolor: A Possible Biological Pretreatment for Biomass
Lignin is an obstacle in large-scale biofuel production. This can be overcome by the use of fungal pretreatment. This experiment assessed two transformation assays, based on the protocols of Laccaria bicolor and Phanerochaete chrysosporium, and applied them to Trametes versicolor. In order to determine a successful transformation, T. versicolor was transformed with green fluorescence protein (GFP) using the two assays, followed by detection of transformed mycelia under UV light. The two protocols were assessed based on timeliness, ease, and effectiveness. Based on the quantity of viable transformants and ease, the membrane assay described for Laccaria is successful when the antibiotic concentration, specifically, is optimized and applied to T. versicolor. This work is also the first to show that the plant-based promoter, cauliflower mosaic virus (CaMV) 35S, is effective for expression of any gene in T. versicolor, a white-rot fungus
White-Rot Fungi as Pretreatment Agents for Wood Destined for Biofuel Applications
Efficient and economical conversion of lignocellulosic biomass to biofuels is often hampered by the chemical recalcitrance of the material. Inexpensive and environmentally-friendly pretreatment processes are therefore desirable in order to lower the cost of biofuel production and minimize negative environmental impacts. To that end, we have explored the use of a naturally occurring white-rot fungus, Trametes versicolor, as a direct pretreatment agent for hardwood destined for biofuel applications. Specifically, we examined the pretreatment effects on the hardwood mixture after treatment with the wild-type strain of T. versicolor (52J) compared with those from a cellobiose dehydrogenase (CDH)-deficient strain (m4D) , to examine how a lack of CDH affects wood pretreatment. The effects of each strain of T. versicolor on the lignocellulose chemistry within the wood were examined after 12 weeks of incubation, as well as the physicochemical properties (pellet strength and energy content). At the laboratory scale, pretreatment with the mutant strain showed altered lignin structure and improved sugar yields, while the wild-type strain led to substantially increased pellet strength without impeding the overall energy content of the pellets. However, at the demonstration scale (150 L), the wild-type strain did not alter pellet strength, despite similar lignin extraction characteristics, glucose content, and energy content when compared to the laboratory scale. Therefore, further research will need to be conducted at the laboratory and demonstration scales to investigate how this fungus alters the structure of lignocellulose at the biochemical level (e.g., transcriptomic analysis), and how fungal pretreatment may affect other biofuel technologies, such as biomass gasification
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