260 research outputs found
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Vegetation classification for the badger allotment, Mt. Hood National Forest
More than 200 sites between 500 and 2000 meters elevation
were examined utilizing a reconnaissance sampling technique for a
portion of the eastern slopes of the northern Oregon Cascade Mountains.
Twelve different forested plant communities were described
with data on vegetation, soils and topography. A map of their distribution
and a key for their identification were presented.
The communities were grouped into four different series based
on climax tree species. The Pinus ponderosa-Quercus garryana
series dominated elevations between 600 and 850 meters and included
four community types. The Quercus garryana/Purshia tridentata/
Agropyron spicatum type was an open Quercus garryana woodland
found on upper southerly slopes with relatively shallow soils. The
Pinus ponderosa-Quercus garryana/Purshia tridentata/Festuca
idahoensis type was the most widespread member of the series and
was found on gentle slopes with east to south aspects. The Pinus/
ponderosa/Purshia tridentata/Lupinus leucophyllus type was found
on gentle east to south facing slopes on flat or convex microrelief.
The Pinus ponderosa/Purshia tridentata Lupinus caudata type was on
gentle east to south facing slopes having concave microrelief.
The Abies grandis series dominated elevations between 850 and
1500 meters and included four community types. The Abies grandis/
Carex geyeri type occupied the lowest elevations within the series and
was found on all aspects and slope positions. The Abies grandis/
Pyrola secunda type was found at the upper elevations on midslopes
with northerly aspects between 1360 and 1415 meters.
The Thuja plicata series was found in stream bottoms and
valleys between 1100 and 1325 meters elevation and included two
community types. The Tsuga plicata/Linnaea borealis var. longiflora
type was found on flat to concave microrelief with soils that had a high
ground water table. The Tsuga heterophylla/Linnaea borealis var.
longiflora type was found on lower sheltered valleys and side slopes.
The Abies amabilis series dominated the upper elevations of
the study area between 1500 and 1960 meters and included two community
types. Tsuga mertensiana was a conspicuous associate with
Abies amabilis. The understory vegetation was often depauperate
and poorly developed. Low shrubs were usually the most dominant
understory species. The Abies amabilis /Rubus lasiococcus type was
found at the lower elevations within the series on a variety of slopes,
aspects and topography. The Abies amabilis/Vaccinium scoparium
type occupied the highest elevations within the study area and subalpine
meadows and openings were commonly interspersed with it.
It occurred on north to east aspects on a variety of slopes and
topography.
Non-forested areas within the study area were not classified but
were briefly described. Some implications for management by community
were also given
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Forested plant associations of the Colville National Forest
A classification of forest vegetation is presented for the Colville National Forest in northeastern
Washington State. It is based on potential vegetation with the plant association as the basic unit. The
classification is based on a sample of approximately 229 intensive plots and 282 reconnaisance plots
distributed across the forest from 1980 to 1983. The hierarchical classification includes 5 forest tree
series and 39 plant associations or community types. Diagnostic keys are presented for each tree
series and plant association or community type. Descriptions include information about plant
association or community species composition, occurrences, distribution, environment, soils, forest
productivity, management implications and relations to other vegetation classifications. Background
information is also presented on the ecology, geology, soils, climate, and fire history of the Colville
National Forest.Keywords: Vegetation classification, climax plant communities, potential vegetation, plant
association, vegetation series, forest ecology, fire, wildife, range, northeastern Washington
The response of perennial and temporary headwater stream invertebrate communities to hydrological extremes
The headwaters of karst rivers experience considerable hydrological variability, including spates and streambed drying. Extreme summer flooding on the River Lathkill (Derbyshire, UK) provided the opportunity to examine the invertebrate community response to unseasonal spate flows, flow recession and, at temporary sites, streambed drying. Invertebrates were sampled at sites with differing flow permanence regimes during and after the spates. Following streambed drying at temporary sites, dewatered surface sediments were investigated as a refugium for aquatic invertebrates. Experimental rehydration of these dewatered sediments was conducted to promote development of desiccation-tolerant life stages. At perennial sites, spate flows reduced invertebrate abundance and diversity, whilst at temporary sites, flow reactivation facilitated rapid colonisation of the surface channel by a limited number of invertebrate taxa. Following streambed drying, 38 taxa were recorded from the dewatered and rehydrated sediments, with Oligochaeta being the most abundant taxon and Chironomidae (Diptera) the most diverse. Experimental rehydration of dewatered sediments revealed the presence of additional taxa, including Stenophylax sp. (Trichoptera: Limnephilidae) and Nemoura sp. (Plecoptera: Nemouridae). The influence of flow permanence on invertebrate community composition was apparent despite the aseasonal high-magnitude flood events
HIV Treatment as Prevention: Debate and Commentary-Will Early Infection Compromise Treatment-as-Prevention Strategies?
Universal HIV testing and immediate antiretroviral therapy for infected individuals has been proposed as a way of reducing the transmission of HIV and thereby bringing the HIV epidemic under control. It is unclear whether transmission during early HIV infectionâbefore individuals are likely to have been diagnosed with HIV and started on antiretroviral therapyâwill compromise the effectiveness of treatment as prevention. This article presents two opposing viewpoints by Powers, Miller, and Cohen, and Williams and Dye, followed by a commentary by Fraser
Search for pentaquark in high statistics measurement of at CLAS
The exclusive reaction was studied in the
photon energy range between 1.6-3.8 GeV searching for evidence of the exotic
baryon . The decay to requires the assignment of
strangeness to any observed resonance. Data were collected with the CLAS
detector at the Thomas Jefferson National Accelerator Facility corresponding to
an integrated luminosity of 70 . No evidence for the
pentaquark was found. Upper limits were set on the production cross section as
function of center-of-mass angle and mass. The 95% CL upper limit on the
total cross section for a narrow resonance at 1540 MeV was found to be 0.8 nb.Comment: Submitted to Physical Review Letter
First measurement of direct photoproduction on the proton
We report on the results of the first measurement of exclusive
meson photoproduction on protons for GeV and GeV. Data were collected with the CLAS detector at the Thomas
Jefferson National Accelerator Facility. The resonance was detected via its
decay in the channel by performing a partial wave analysis of the
reaction . Clear evidence of the meson
was found in the interference between and waves at GeV. The -wave differential cross section integrated in the mass range of
the was found to be a factor of 50 smaller than the cross section
for the meson. This is the first time the meson has been
measured in a photoproduction experiment
Retail sector distribution chains for malaria treatment in the developing world: a review of the literature
BACKGROUND: In many low-income countries, the retail sector plays an important role in the treatment of malaria and is increasingly being considered as a channel for improving medicine availability. Retailers are the last link in a distribution chain and their supply sources are likely to have an important influence on the availability, quality and price of malaria treatment. This article presents the findings of a systematic literature review on the retail sector distribution chain for malaria treatment in low and middle-income countries. METHODS: Publication databases were searched using key terms relevant to the distribution chain serving all types of anti-malarial retailers. Organizations involved in malaria treatment and distribution chain related activities were contacted to identify unpublished studies. RESULTS: A total of 32 references distributed across 12 developing countries were identified. The distribution chain had a pyramid shape with numerous suppliers at the bottom and fewer at the top. The chain supplying rural and less-formal outlets was made of more levels than that serving urban and more formal outlets. Wholesale markets tended to be relatively concentrated, especially at the top of the chain where few importers accounted for most of the anti-malarial volumes sold. Wholesale price mark-ups varied across chain levels, ranging from 27% to 99% at the top of the chain, 8% at intermediate level (one study only) and 2% to 67% at the level supplying retailers directly. Retail mark-ups tended to be higher, and varied across outlet types, ranging from 3% to 566% in pharmacies, 29% to 669% in drug shops and 100% to 233% in general shops. Information on pricing determinants was very limited. CONCLUSIONS: Evidence on the distribution chain for retail sector malaria treatment was mainly descriptive and lacked representative data on a national scale. These are important limitations in the advent of the Affordable Medicine Facility for Malaria, which aims to increase consumer access to artemisinin-based combination therapy (ACT), through a subsidy introduced at the top of the distribution chain. This review calls for rigorous distribution chain analysis, notably on the factors that influence ACT availability and prices in order to contribute to efforts towards improved access to effective malaria treatment
Macrophages retain hematopoietic stem cells in the spleen via VCAM-1
Splenic myelopoiesis provides a steady flow of leukocytes to inflamed tissues, and leukocytosis correlates with cardiovascular mortality. Yet regulation of hematopoietic stem cell (HSC) activity in the spleen is incompletely understood. Here, we show that red pulp vascular cell adhesion molecule 1 (VCAM-1)[superscript +] macrophages are essential to extramedullary myelopoiesis because these macrophages use the adhesion molecule VCAM-1 to retain HSCs in the spleen. Nanoparticle-enabled in vivo RNAi silencing of the receptor for macrophage colony stimulation factor (M-CSFR) blocked splenic macrophage maturation, reduced splenic VCAM-1 expression and compromised splenic HSC retention. Both, depleting macrophages in CD169 iDTR mice or silencing VCAM-1 in macrophages released HSCs from the spleen. When we silenced either VCAM-1 or M-CSFR in mice with myocardial infarction or in ApoE[superscript â/â] mice with atherosclerosis, nanoparticle-enabled in vivo RNAi mitigated blood leukocytosis, limited inflammation in the ischemic heart, and reduced myeloid cell numbers in atherosclerotic plaques
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