66 research outputs found
Armillaria Root Rot in Eucalypt Forests: Aggravated Endemic Disease
Species of the woody root rot fungus Armillaria are indigenous
in cool temperate rain forest, mixed forest, and wet and dry sclerophyll
eucalypt forests in Australia. Four species have been described or identified
from southeastern Australia: A. luteobubalina Watling and Kile, A. fumosa
Kile and Watling, A. hinnulea Kile and Watling, and A. novae-zelandiae
(Stevenson) Boesewinkel. The latter species was first described from New
Zealand, and A. hinnulea also occurs in that country. Armillaria novae-zelandiae
and A. hinnulea occur in wet forests (rain forest, mixed forest, and wet sclerophyll
communities), while A. luteobubalina and A. fumosa are found mainly in
dry sclerophyll forests.
Armillaria luteobubalina is so far the only species known to behave as a
primary pathogen in native forests. While the fungus has an extensive geographical
distribution in southeastern Australia, damage is most severe in
selectively logged forests in the central highlands of Victoria, where it is
estimated that approximately 3-5% of the forest area is moderately to severely
affect~. The fungus kills all species of eucalypts and a wide range of the under-
story trees and shrubs present in the forests. Most infections occur in small
(0.1-1.0 ha), well-defined patches, but larger (up to 20-30 ha), more diffuse
infections also occur. Evidence of primary pathogenicity includes (a) constant
association of the fungus with disease; (b) the pattern of disease development
within stands (the fungus spreads by root contact from infected food bases);
(c) correlation between root infection and symptom development in large trees;
(d) evidence of host resistance to infection; and (e) pathogenicity in pot and
field trials. There is no evidence that climatic stress or other pests or pathogens
initiate disease.
Within the forest, the fungus has a discontinuous distribution. Studies of
genotypes of the fungus (identified by analyses of mating alleles, since Armillaria
sp. are bifactorial heterothallic, or intraspecific antagonism), suggest that A.
luteobubalina consists of a community of genetically distinct mycelia. Individual
genotypes may contract, expand, or coalesce, depending on circumstance. The
development and status of the community depends on the two processes of
new basidiospore infection and local spread by vegetative growth through root
systems. Similar patterns of genotype distribution and clonal development were
evident in logged and unlogged forest. It is concluded that root rot caused by
the fungus is endemic in these forests but that logging has aggravated the disease
Search for the glueball candidates f0(1500) and fJ(1710) in gamma gamma collisions
Data taken with the ALEPH detector at LEP1 have been used to search for gamma
gamma production of the glueball candidates f0(1500) and fJ(1710) via their
decay to pi+pi-. No signal is observed and upper limits to the product of gamma
gamma width and pi+pi- branching ratio of the f0(1500) and the fJ(1710) have
been measured to be Gamma_(gamma gamma -> f0(1500)). BR(f0(1500)->pi+pi-) <
0.31 keV and Gamma_(gamma gamma -> fJ(1710)). BR(fJ(1710)->pi+pi-) < 0.55 keV
at 95% confidence level.Comment: 10 pages, 3 figure
Constraints on anomalous QGC's in interactions from 183 to 209 GeV
The acoplanar photon pairs produced in the reaction e(+) e(-) - → vvyy are analysed in the 700 pb(-1) of data collected by the ALEPH detector at centre-of-mass energies between 183 and 209 GeV. No deviation from the Standard Model predictions is seen in any of the distributions examined. The resulting 95% C.L. limits set on anomalous QGCs, a(0)(Z), a(c)(Z), a(0)(W) and a(c)(W), are -0.012 lt a(0)(Z)/Lambda(2) lt +0.019 GeV-2, -0.041 lt a(c)(Z)/Lambda(2) lt +0.044 GeV-2, -0.060 lt a(0)(W)/Lambda(2) lt +0.055 GeV-2, -0.099 lt a(c)(W)/Lambda(2) lt +0.093 GeV-2, where Lambda is the energy scale of the new physics responsible for the anomalous couplings
Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures
Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo
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