2,168 research outputs found
Storing Tender Bulbs and Bulblike Structures
FS-1117-A Revised 1998Meyer, Mary H.. (1998). Storing Tender Bulbs and Bulblike Structures. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/219503
Water Quality Characteristics of Three Rain Gardens Located Within the Twin Cities Metropolitan Area, Minnesota
A study was conducted by the United States Geological Survey (USGS) at three locations in the Twin Cities Metropolitan Area in Minnesota to assess the effect that bioretention areas, or rain gardens, have on water quality. The rain gardens are located at the University of Minnesota Landscape Arboretum (MLA), City of Hugo, and City of Woodbury. These sites were chosen because of their similar ages, differences in design, surrounding land use, precipitation patterns, and geology. This article reports the statistical analysis of six years of data obtained from these three sites. The data characterizes the water quality of the inflow, overflow, vadose zone, and groundwater of each rain garden. Nutrients analyzed included chloride, total suspended solids, ammonia, organic nitrogen, nitrate, and phosphorus. Lysimeters and wells had significantly lower nutrient concentrations compared to inflow for most nutrients. Increased nitrate occurred in the vadose zone at Woodbury and Hugo, suggesting some production of nitrate within the soil profile; however, groundwater beneath the rain gardens contained significantly lower concentrations of nitrate compared to the inflow, providing evidence of nitrate removal at deeper depths. Phosphorus concentrations were reduced in overflow and groundwater, with the exception of dissolved phosphorus at MLA. Rain garden and background wells often contained similar nutrient concentrations, suggesting that the rain gardens had little impact on the local ground water supplies. This unique six year study provides consistent evidence of the ability of these three rain gardens to reduce nutrient concentrations from urban stormwater
Systems Modeling Identifies Divergent Receptor Tyrosine Kinase Reprogramming to MAPK Pathway Inhibition
Introduction - Targeted cancer therapeutics have demonstrated more limited clinical efficacy than anticipated, due to both intrinsic and acquired drug resistance. Underlying mechanisms have been largely attributed to genetic changes, but a substantial proportion of resistance observations remain unexplained by genomic properties. Emerging evidence shows that receptor tyrosine kinase (RTK) reprogramming is a major alternative process causing targeted drug resistance, separate from genetic alterations. Hence, the contributions of mechanisms leading to this process need to be more rigorously assessed.National Institutes of Health (U.S.) (Grant R01-CA96504)National Institutes of Health (U.S.) (Grant U54-CA217377)United States. Army Research Office (grant W911NF-09-0001
Investigating Hydrologic Alteration as a Mechanism of Fish Assemblage Shifts in Urbanizing Streams
Stream biota in urban and suburban settings are thought to be impaired by altered hydrology; however, it is unknown what aspects of the hydrograph alter fish assemblage structure and which fishes are most vulnerable to hydrologic alterations in small streams. We quantified hydrologic variables and fish assemblages in 30 small streams and their subcatchments (area 8-20 km 2) in the Etowah River Catchment (Georgia, USA). We stratified streams and their subcatchments into 3 landcover categories based on imperviousness (20% of subcatchment), and then estimated the degree of hydrologic alteration based on synoptic measurements of baseflow yield. We derived hydrologic variables from stage gauges at each study site for 1 y (January 2003-2004). Increased imperviousness was positively correlated with the frequency of storm events and rates of the rising and falling limb of the hydrograph (i.e, storm flashiness ) during most seasons. Increased duration of low flows associated with imperviousness only occurred during the autumn low-flow period, and this measure corresponded with increased richness of lentic tolerant species. Altered storm flows in summer and autumn were related to decreased richness of endemic, cosmopolitan, and sensitive fish species, and decreased abundance of lentic tolerant species. Species predicted to be sensitive to urbanization, based on specific life-history or habitat requirements, also were related to stormflow variables and % fine bed sediment in riffles. Overall, hydrologic variables explained 22 to 66% of the variation in fish assemblage richness and abundance Linkages between hydrologic alteration and fish assemblages were potentially complicated by contrasting effects of elevated flows on sediment delivery and scour, and mediating effects of high stream gradient on sediment delivery from elevated flows. However, stormwater management practices promoting natural hydrologic regimes are likely to reduce the impacts of catchment imperviousness on stream fish assemblages. ?? 2005 by The North American Benthological Societ
Rigid linkages and partial zero forcing
Connections between vital linkages and zero forcing are established.
Specifically, the notion of a rigid linkage is introduced as a special kind of
unique linkage and it is shown that spanning forcing paths of a zero forcing
process form a spanning rigid linkage and thus a vital linkage. A related
generalization of zero forcing that produces a rigid linkage via a coloring
process is developed. One of the motivations for introducing zero forcing is to
provide an upper bound on the maximum multiplicity of an eigenvalue among the
real symmetric matrices described by a graph. Rigid linkages and a related
notion of rigid shortest linkages are utilized to obtain bounds on the
multiplicities of eigenvalues of this family of matrices.Comment: 23 page
University of Minnesota Extension Master Gardener CenUSA Biochar Demonstration Gardens 2012-2015
Soil serves as the foundation of all gardens, and thus incorporating beneficial amendments before planting is of the utmost importance to a healthy, roductive crop. Increased interest and research in biomass and biofuels has promoted the use of biochar, a coproduct of the pyrolysis process, as one
amendment to improve soil health. Urban soils, the site of many home and community gardens, can be carbon-poor, so we wondered if biochar would benefit home gardeners and grow more productive plants. Soils at four demonstration sites in Minnesota were amended with hardwood biochar. With the
help of Extension Master Gardener volunteers, we grew, harvested and measured common garden crops over four years to see if those grown in biochar-amended soils were more productive. Variables in weather, crops and volunteer interpretation of data did not provide conclusive results. However, the poorer soils amended with biochar showed some increase in soil pH and percent organic matter, and clay loam soils were less compacted. Most crop yields showed improvement over the four years; however, we believe these increased yields were likely affected by a combination of factors (rainfall, air
temperatures) and cannot be directly attributed to the addition of biochar.AFRI-CAP Competitive Grant No. 2011-68005-30411 from NIFADavenport-Hagen, Lynne; Weisenhorn, Julie; Meyer, Mary H.; Sui, Luna Xiaoye. (2017). University of Minnesota Extension Master Gardener CenUSA Biochar Demonstration Gardens 2012-2015. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/189778
Quiescent Radio Emission from Southern Late-type M Dwarfs and a Spectacular Radio Flare from the M8 Dwarf DENIS 1048-3956
We report the results of a radio monitoring program conducted at the
Australia Telescope Compact Array to search for quiescent and flaring emission
from seven nearby Southern late-type M and L dwarfs. Two late-type M dwarfs,
the M7 V LHS 3003 and the M8 V DENIS 1048-3956, were detected in quiescent
emission at 4.80 GHz. The observed emission is consistent with optically thin
gyrosynchrotron emission from mildly relativistic (~1-10 keV) electrons with
source densities n_e ~ 10 G magnetic fields. DENIS
1048-3956 was also detected in two spectacular, short-lived flares, one at 4.80
GHz (peak f_nu = 6.0+/-0.8 mJy) and one at 8.64 GHz (peak f_nu = 29.6+/-1.0
mJy) approximately 10 minutes later. The high brightness temperature (T_B >~
10^13 K), short emission period (~4-5 minutes), high circular polarization
(~100%), and apparently narrow spectral bandwidth of these events imply a
coherent emission process in a region of high electron density (n_e ~
10^11-10^12 cm^-3) and magnetic field strength (B ~ 1 kG). If the two flare
events are related, the apparent frequency drift in the emission suggests that
the emitting source either moved into regions of higher electron or magnetic
flux density; or was compressed, e.g., by twisting field lines or gas motions.
The quiescent fluxes from the radio-emitting M dwarfs violate the Gudel-Benz
empirical radio/X-ray relations, confirming a trend previously noted by Berger
et al. (abridged)Comment: 28 pages, 8 figures, accepted for publication in Ap
Muscle-specific knockout of general control of amino acid synthesis 5 (GCN5) does not enhance basal or endurance exercise-induced mitochondrial adaptation
Objective Lysine acetylation is an important post-translational modification that regulates metabolic function in skeletal muscle. The acetyltransferase, general control of amino acid synthesis 5 (GCN5), has been proposed as a regulator of mitochondrial biogenesis via its inhibitory action on peroxisome proliferator activated receptor-γ coactivator-1α (PGC-1α). However, the specific contribution of GCN5 to skeletal muscle metabolism and mitochondrial adaptations to endurance exercise in vivo remain to be defined. We aimed to determine whether loss of GCN5 in skeletal muscle enhances mitochondrial density and function, and the adaptive response to endurance exercise training. Methods We used Cre-LoxP methodology to generate mice with muscle-specific knockout of GCN5 (mKO) and floxed, wildtype (WT) littermates. We measured whole-body energy expenditure, as well as markers of mitochondrial density, biogenesis, and function in skeletal muscle from sedentary mice, and mice that performed 20 days of voluntary endurance exercise training. Results Despite successful knockdown of GCN5 activity in skeletal muscle of mKO mice, whole-body energy expenditure as well as skeletal muscle mitochondrial abundance and maximal respiratory capacity were comparable between mKO and WT mice. Further, there were no genotype differences in endurance exercise-mediated mitochondrial biogenesis or increases in PGC-1α protein content. Conclusion These results demonstrate that loss of GCN5 in vivo does not promote metabolic remodeling in mouse skeletal muscle
Delays in Leniency Application: Is There Really a Race to the Enforcer's Door?
This paper studies cartelsâ strategic behavior in delaying leniency applications, a take-up decision that has been ignored in the previous literature. Using European Commission decisions issued over a 16-year span, we show, contrary to common beliefs and the existing literature, that conspirators
often apply for leniency long after a cartel collapses. We estimate hazard and probit models to study the determinants of leniency-application delays. Statistical tests find that delays are symmetrically affected by antitrust policies and macroeconomic fluctuations. Our results shed light on the design of
enforcement programs against cartels and other forms of conspiracy
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