454 research outputs found
Riparian forests with and without grass filters as buffers of concentrated flow from crop fields
Paper presented at the 11th North American Agroforesty Conference, which was held May 31-June 3, 2009 in Columbia, Missouri.In Gold, M.A. and M.M. Hall, eds. Agroforestry Comes of Age: Putting Science into Practice. Proceedings, 11th North American Agroforestry Conference, Columbia, Mo., May 31-June 3, 2009.A vegetation inventory within naturally occurring forested riparian buffers (natural forest buffers) and a survey comparing buffering of concentrated flow paths (CFPs) by natural forest buffers with and without planted grass filters was conducted along first and second order streams in three northeast Missouri watersheds. Seven natural forest buffers without grass filters were inventoried and found to be composed of dense stands of mixed tree species with a forest floor cover comprised largely of unrooted woody plant debris, which does not adequately buffer concentrated runoff. Seventy-four CFPs were found in row crop fields along 10 natural forest buffers with or without grass filters established using USDA conservation practice standards. Natural forest buffers without grass filters dispersed 80 [percent] of CFPs before they reached the stream, while those with grass filters dispersed 100 [percent]. We estimated 473 metric tons of sediment moved to the buffers/filters via CFPs since last tillage. Nine of the 74 CFPs passed completely through natural forest buffers without grass filters, and accounted for 97 metric tons of the total estimated 473 metric tons. The average width of breached forest buffers without grass filters was 12.8 m, while the width of those not breached was 17.9 m. Average width of cool-season grass filters (CSGF) adjacent to forest buffers was 17.6 m, while average width of warm season grass filters (WSGF) was 22.1 m. These data, along with previous research, suggest that adding a grass filter along narrow natural forest buffers would improve water quality by reducing sediment loss to streams.K.W. Knight (1), R.C. Schultz (2), C.M. Mabry (2), T.M. Isenhart (2), and L. Long (2) ; 1. The Nature Conservancy, Skagit River Office, 410 N. 4th St., Mt. Vernon, WA 98273. 2. Dept. of Natural Resource Ecology and Management, Iowa State University, 339 Science II, Ames, Iowa 50011-3221.Includes bibliographical references
Self-assembly of magnetic biofunctional nanoparticles
Spherical, ferromagnetic FePt nanoparticles with a particle size of 3 nm were prepared by the simultaneous polyol reduction of Fe(acac)3Fe(acac)3 and Pt(acac)2Pt(acac)2 in phenyl ether in the presence of oleic acid and oleylamine. The oleic acid ligands can be replaced with 11-mercaptoundecanoic acid, giving particles that can be dispersed in water. Both x-ray diffraction and transmission electron microscopy indicated that FePt particles were not affected by ligands replacement. Dispersions of the FePt particles with 11-mercaptoundecanoic acid ligands and ammonium counter ions gave self-assembled films consisting of highly ordered hexagonal arrays of particles.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87511/2/10Q901_1.pd
Light noble gas composition of different solar wind regimes: results from genesis
The Genesis mission provided samples of solar wind
(SW) from different regions on the Sun. These SW regime samples are
important in understanding fractionation processes upon formation and
acceleration of the SW to ultimately deduce solar composition from SW
values. We present He and Ne isotopic and elemental compositions of the
bulk SW (SW of entire collection period) and the 3 major SW regimes: slow
(from the ecliptic plane, emanating from above streamers), fast (emanating
from coronal holes), and coronal mass ejections (CME). At the conference
we will also present Ar data
Mass-fractionation induced by the Genesis solar wind concentrator: Analysis of neon isotopes by UV laser ablation
The solar wind (SW) concentrator, a key instrument onboard the
Genesis mission, was designed to provide larger fluences of implanted SW
for precise isotope analyses of oxygen and nitrogen [1]. SW ions in the mass
range 4–28 amu were accelerated and focused on a “concentrator target” by
an electrostatic mirror. This concentration process caused some instrumental
mass fractionation of the implanted SW ions as function of the radial position
on the target. Correction of this fractionation will be based on a combination
of the measured radial fractionation of Ne isotopes with results of simulations
of the implantation process using the actual performance of the concentrator
and the SW conditions during exposure. Here we present He and Ne
abundance and Ne isotopic composition data along one arm of the gold cross
that framed the 4 concentrator subtargets
School librarians as literacy educators within a complex role
Librarians in schools are expected to play an important role as literacy educators, and have a positive impact on young people’s literacy learning. However in the context of their diverse workload, relatively little is known about how this aspect of their role sits within its competing demands, and the exact scope of the literacy educator requirements. Using a hybrid approach to content analysis, this article analyses 40 recent job description documents to identify the nature and prevalence of different aspects of the role, and to explore the literacy educator aspect of this profession. Findings suggest that while the literacy educator aspect is one of the most common role requirements, it sits within a complex workload, and the literacy educator aspect is itself multi-faceted and demanding
Preliminary studies of Xe and Kr from the Genesis polished aluminium collector
Low solar wind (SW) abundances of Xe and Kr require
a large collector area to provide measurable quantities of these rare gases.
Originally we planned to use large areas of Al on Sapphire (AloS) collectors,
but the hard landing of Genesis fractured these collectors, changing our initial
plans. The only large, relatively intact, surface exposed to SW was the
kidney-shaped polished aluminum T6-6061 alloy (AlK) designed to serve as
a thermal shield rather than a SW collector. Here we describe what has been
done and the problems remaining to be solved for optimized Xe and Kr
abundances and isotopic compositions from the AlK
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Carbon stable isotope analysis of cereal remains as a way to reconstruct water availability: preliminary results
Reconstructing past water availability, both as rainfall and irrigation, is important to answer questions about the way society reacts to climate and its changes and the role of irrigation in the development of social complexity. Carbon stable isotope analysis of archaeobotanical remains is a potentially valuable method for reconstructing water availability. To further define the relationship between water availability and plant carbon isotope composition and to set up baseline values for the Southern Levant, grains of experimentally grown barley and sorghum were studied. The cereal crops were grown at three stations under five different irrigation regimes in Jordan. Results indicate that a positive but weak relationship exists between irrigation regime and total water input of barley grains, but no relationship was found for sorghum. The relationship for barley is site-specific and inter-annual variation was present at Deir ‘Alla, but not at Ramtha and Khirbet as-Samra
Solar neon released from Genesis aluminum collector duriung stepped uv-laser extraction and step-wise pyrolysis
Earlier this year we reported results of UV-laser stepped raster extractions of Ne and He from Genesis' Al-collector [l]. Since then, using pyrolysis of a 0.005 cm^2 fragment of this material left from the earlier study, we have estimated the efficiency of the UV-laser extraction to be at least 95%. We also analyzed Ne released from the Al-collector by means of stepped pyrolysis. Here we compare these new data with stepped UV-laser extraction and the CSSE results [2]. Figure 1 shows the ^(20)Ne/^(22)Ne ratio extracted from Genesis collectors using these three techniques
Argon and neon in Genesis aluminum-coated sapphire collectors from regime arrays
Here we report Ar results from the aluminum on sapphire (AloS) bulk regime samples, from which Ne results were obtained [1]. Ar measurements from other regimes are in progress
Psychomotor impairments and therapeutic implications revealed by a mutation associated with infantile Parkinsonism-Dystonia
Parkinson disease (PD) is a progressive, neurodegenerative disorder affecting over 6.1 million people worldwide. Although the cause of PD remains unclear, studies of highly penetrant mutations identified in early-onset familial parkinsonism have contributed to our understanding of the molecular mechanisms underlying disease pathology. Dopamine (DA) transporter (DAT) deficiency syndrome (DTDS) is a distinct type of infantile parkinsonism-dystonia that shares key clinical features with PD, including motor deficits (progressive bradykinesia, tremor, hypomimia) and altered DA neurotransmission. Here, we define structural, functional, and behavioral consequences of a Cys substitution at R445 in human DAT (hDAT R445C), identified in a patient with DTDS. We found that this R445 substitution disrupts a phylogenetically conserved intracellular (IC) network of interactions that compromise the hDAT IC gate. This is demonstrated by both Rosetta molecular modeling and fine-grained simulations using hDAT R445C, as well as EPR analysis and X-ray crystallography of the bacterial homolog leucine transporter. Notably, the disruption of this IC network of interactions supported a channel-like intermediate of hDAT and compromised hDAT function. We demonstrate that Drosophila melanogaster expressing hDAT R445C show impaired hDAT activity, which is associated with DA dysfunction in isolated brains and with abnormal behaviors monitored at high-speed time resolution. We show that hDAT R445C Drosophila exhibit motor deficits, lack of motor coordination (i.e. flight coordination) and phenotypic heterogeneity in these behaviors that is typically associated with DTDS and PD. These behaviors are linked with altered dopaminergic signaling stemming from loss of DA neurons and decreased DA availability. We rescued flight coordination with chloroquine, a lysosomal inhibitor that enhanced DAT expression in a heterologous expression system. Together, these studies shed some light on how a DTDS-linked DAT mutation underlies DA dysfunction and, possibly, clinical phenotypes shared by DTDS and PD
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