4,940 research outputs found
Research Progress Report, No. 17
Legumes are notable for their ability to convert atmospheric dinitrogen into forms of
nitrogen which are usable by plants. This is done in association with bacteria (called
Rhizobium) which inhabit nodules of the plant roots. This process is called nitrogen-fixation. Legumes are important as forage and food crops due to their high protein content. Some are also useful for soil conservation purposes. There was no information on nitrogen fixation by legume crops in Alaska. This research was initiated to determine how much nitrogen different types of legumes can fix in interior Alaska
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Annular variability and eddy-zonal flow interactions in a simplified atmospheric GCM. Part 1: Characterization of high and low frequency behaviour
Experiments have been performed using a simplified, Newtonian forced, global circulation model to investigate how variability of the tropospheric jet can be characterized by examining the combined fluctuations of the two leading modes of annular variability. Eddy forcing of this variability is analyzed in the phase space of the leading modes using the vertically integrated momentum budget. The nature of the annular variability and eddy forcing depends on the time scale. At low frequencies the zonal flow and baroclinic eddies are in quasi equilibrium and anomalies propagate poleward. The eddies are shown primarily to reinforce the anomalous state and are closely balanced by the linear damping, leaving slow evolution as a residual. At high frequencies the flow is strongly evolving and anomalies are initiated on the poleward side of the tropospheric jet and propagate equatorward. The eddies are shown to drive this evolution strongly: eddy location and amplitude reflect the past baroclinicity, while eddy feedback on the zonal flow may be interpreted in terms of wave breaking associated with baroclinic life cycles in lateral shear
MP 2012-02
Final report to BP.The Prudhoe Bay oil fields, Alaska were discovered in 1968,
and commercial production commenced in 1977 with the
completion of the Trans-Alaska Pipeline. Oil production has
been declining since 1989, although additional exploratory
drilling continues. Support facilities for oil production are
built on permafrost soils that surface-thaw in summer to form
extensive wetlands composed of moist meadows, sedge marshes,
moist sedge-dwarf shrub tundra, grass marshes, small ponds
and lakes (Walker and Acevedo 1987). To prevent thawing and
subsidence of subsurface, ice-rich soils, gravel pads, 2m (6 ft) or
more thickness have been built to support drilling sites as well as
roads, airstrips and building pads (Kidd et al. 2006). As well sites
are decommissioned, the gravel is wholly or partially removed
resulting in the need for site rehabilitation and/or restoration to
support wetland plants and, in some instances, enhance wildlife
habitat (McKendrick 1991, Jorgenson and Joyce 1994, Kidd et
al. 2004, 2006). Since the 1970s, methods to revegetate arctic wetlands have
included a variety of planting techniques, seed treatments,
seeding with native and non-native species (mostly grasses),
and fertilizer applications (Chapin and Chapin 1980; Bishop
and Chapin 1989, Jorgenson 1988, Kidd and Rossow 1998,
Kidd et al. 2004, 2006, Maslen and Kershaw 1989, McKendrick
1987, 1991, 2000, McKendrick et al. 1980, McKendrick and
Mitchell 1978, Mitchell et al. 1974). Treatments also have
included sprigging and plug transplantation (Kidd et al. 2004,
2006), surface manipulation (Streever et al. 2003), as well as
natural re-colonization (Ebersole 1987, Schwarzenbach 1996).
These methods have been partially successful. The gravelly soils
often are dry, nutrient-poor, and have a higher pH and lower
organic matter content than surrounding soils, so natural recolonization
does not occur readily (Bishop and Chapin 1989,
Jorgenson and Joyce 1994). Methods such as sprigging and plug
transplanting are slow, labor intensive and expensive compared
to direct seeding. Fertilization, especially with phosphorus, is
recommended for long-term survival of plants grown on gravelly
sandy soils (BP Exploration and McKendrick 2004).
Two common species in the arctic coastal wetlands are water
sedge, Carex aquatilis Wahlenb. and cotton sedge, Eriophorum
angustifolium Honck. Carex aquatilis in particular forms large
populations that spread vegetatively by rhizomes and often
dominate these wetland environments (Shaver and Billings
1975). Despite their abundance, these species have not been
considered for revegetation because of poor seed germination
and inadequate information on seed development and viability
(Dr. William Streever, BP Alaska, pers. comm.). Both Carex and
Eriophorum in arctic environments produce abundant seeds, but
seed viability and germination often is low and highly variable
among years and locations (Archibold 1984, Billings and
Mooney 1968, Ebersole 1989, Gartner et al. 1983).
Germination recommendations for both species vary by
location and have included an array of pretreatments such as light, alternating temperatures, cold stratification, scarification,
and high and low temperature dry storage (Amen 1966, Billings
and Mooney 1960, Bliss 1958, Hunt and Moore 2003, Johnson
et al. 1965, Phillips 1954 and Steinfeld 2001). The purpose
of this project was to explore methods of seed germination of
Carex aquatilis and Eriophorum angustifolium, to learn the
conditions for germination and dormancy control mechanisms,
and identify seed treatments that might enhance germination
for eventual use in direct-seeding or plug production for arctic
wetland revegetation
MP 2009-09
As the price of traditional fossil fuels escalates, there is
increasing interest in using renewable resources, such as
biomass, to meet our energy needs. Biomass resources are of
particular interest to communities in interior Alaska, where
they are abundant (Fresco, 2006). Biomass has the potential
to partially replace heating oil, in addition to being a possible source for electric power generation (Crimp and Adamian, 2000;
Nicholls and Crimp, 2002; Fresco, 2006). The communities of
Tanana and Dot Lake have already installed small Garn boilers to
provide space heating for homes and businesses (Alaska Energy
Authority, 2009). A village-sized combined heat and power
(CHP) demonstration project has been proposed in North Pole.
In addition, several Fairbanks area organizations are interested in
using biomass as a fuel source. For example, the Fairbanks North
Star Borough is interested in using biomass to supplement coal
in a proposed coal-to-liquids project, the Cold Climate Housing
Research Center is planning to test a small biomass fired CHP
unit, and the University of Alaska is planning an upgrade to
its existing coal-fired power plant that could permit co-firing
with biomass fuels. The challenge for all of these projects is in
ensuring that biomass can be harvested on both an economically
and ecologically sustainable basis
No-till Forage Establishment in Alaska
We assessed the effectiveness of no-till forage establishment at six Alaska locations: Anchor Point, Sterling, Point MacKenzie, Palmer, Delta Junction, and Fairbanks. Directly seeding grass into established grass stands generally did not improve forage yields or quality. Seeding rate had little effect on establishment of newly seeded forages in no-till. Grass yields were depressed when companion crop yields were high, and they typically did not recover in subsequent years. Red clover established well, producing high yields of good quality forage under no-till at Point MacKenzie, but established poorly at Anchor Point and Delta Junction. These results indicated that no-till seeding of most forage crops into declining grass stands is not likely to be successful in Alaska with current available technology
Progression from ocular hypertension to visual field loss in the English hospital eye service
Background There are more than one million National Health Service visits in England and Wales each year for patients with glaucoma or ocular hypertension (OHT). With the ageing population and an increase in optometric testing, the economic burden of glaucoma-related visits is predicted to increase. We examined the conversion rates of OHT to primary open-angle glaucoma (POAG) in England and assessed factors associated with risk of conversion.
Methods Electronic medical records of 45â309 patients from five regionally different glaucoma clinics in England were retrospectively examined. Conversion to POAG from OHT was defined by deterioration in visual field (two consecutive tests classified as stage 1 or worse as per the glaucoma staging system 2). Cox proportional hazards models were used to examine factors (age, sex, treatment status and baseline intraocular pressure (IOP)) associated with conversion.
Results The cumulative risk of conversion to POAG was 17.5% (95% CI 15.4% to 19.6%) at 5 years. Older age (HR 1.35 per decade, 95%âCI 1.22 to 1.50, p<0.001) was associated with a higher risk of conversion. IOP-lowering therapy (HR 0.45, 95%âCI 0.35 to 0.57, p<0.001) was associated with a lower risk of conversion. Predicted 5-year conversion rates for treated and untreated groups were 14.0% and 26.9%, respectively.
Conclusion Less than one-fifth of OHT patients managed in glaucoma clinics in the UK converted to POAG over a 5-year period, suggesting many patients may require less intensive follow-up. Our study provides real-world evidence for the efficacy of current management (including IOP-lowering treatment) at reducing risk of conversion
Social Health Insurance for the Poor: Targeting and Impact of Indonesia\u27s Askeskin Program
A first step towards meeting Indonesia\u27s ambition for universal health insurance was made in 2005 with the introduction of the health insurance for the poor (askeskin) program, a subsidized social health insurance targeted on the poor and the informal sector. this scheme covered basic healthcare in public health clinics and hospital inpatient care. in this paper we investigate targeting and impact of the askeskin program using household panel data. we find that the program is indeed targeted on the poor and those most vulnerable to catastrophic out-of-pocket health payments. the public health insurance improves access to healthcare in that it increases utilization of outpatient healthcare among the poor, while out-of-pocket spending seems to have increased for askeskin insured in urban areas.
keywords: social health insurance, healthcare utilization, out-of-pocket health payments, targeting, impact evaluation, Indonesia
jel classification: g22, h55, i1
Electron Emission From Foils Induced By Energetic Heavy-ion Impact
Doubly differential cross sections have been measured and calculated for the electron emission produced by collisions of 3.5 MeV uâ1 U38+ on thin carbon foils. The electron emission is observed in both forward and backward directions. Calculations are in reasonable agreement with the experimental results in both shape and absolute magnitude. At intermediate foil thicknesses, a double binary peak structure is observed that is due to 0° binary electrons being elastically scattered to angle Ξ along with those that are produced at Ξ and suffer no large-angle scattering events in the foil. Absolute electron yields show that several hundred electrons are released per ion impact. The computed time evolution of the forwardly emitted electrons indicates that the electrons tend to follow the ion for thin foils, but precede the ion in thick foils. © 1992 IOP Publishing Ltd
The Mobility Enterprise - Improving Auto Productivity
The Mobility Enterprise is a particular version of a shared vehicle fleet, aimed at solving the problem of low automobile productivity. The automobile consumes a large portion of Americaâs transportation energy supply. It also operates much of the time with unused capacity: vacant seats and empty cargo space. Since programs to fill those vacant seats âride sharing and high occupancy vehicle incentives âhave fallen so far short of their objectives, a new approach is warranted. The enterpriseâs central concept is matching vehicle attributes to travel needs. Generally, a household purchases vehicles for those few trips that require a large capacity, rather than for the majority of trips (usually to work) that have minimal vehicular needs. If a household could tailor its âimmediate accessâ fleet to these frequent trips and still retain reasonable access to larger-capacity special purpose vehicles (SPVâs), considerable economies could be achieved. The household is relieved of owning seldom-used excess capacity, and automobile productivity and efficiency are greatly improved. Having easy access to a shared fleet of SPVâs also affords a household an increase in the quality and economy of its travel experiences. This paper describes a research project recently begun at Purdue that involves a comprehensive investigation of the Mobility Enterprise concept. Questions of institutional barriers, consumer response, and organization and management are discussed here as keys to the fate of the enterprise in the transportation climate of the foreseeable future
Plasma As A High-charge-state Projectile Stripping Medium
The classical trajectory Monte Carlo model has been used to computationally study the charge-state distributions that result from interactions between a high-energy, multielectron projectile and neutral and fully ionized targets. These studies are designed to determine the properties of a plasma for producing highly stripped ions as a possible alternative to gas and foil strippers that are commonly used to enhance the charge states of energetic ion beams. The results of these studies clearly show that a low-atomic-number, highly ionized plasma can yield higher charge states than a neutral target of the same density. The effect is principally attributable to the reduction in the number of available electron-capture channels. In this article, we compare the charge-state distributions that result during passage of a 20-MeV Pb projectile through neutral gas and fully ionized (singly charged) plasma strippers and estimate the effects of multiple scattering on the quality of the beam. © 1992 The American Physical Society
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