958 research outputs found
Ecology and conservation of Alseuosmia quercifolia (Alseuosmiaceae) in the Waikato region, New Zealand
The ecology of Alseuosmia quercifolia, a small endemic shrub, was investigated, focussing on its habitat requirements, population dynamics, phenology and reproductive biology, and conservation status. This species occurs most commonly in lowland native forests of the Waikato region of the North Island (north of latitude 38°05'S), but is also found in scattered populations to North Cape. In the Waikato region it typically occupies shady, well-drained, south or south-east facing lower slopes of hills and ranges at altitudes below 400 m. Population structures show considerable variation amongst seven study sites in the Waikato region, with disjunct size classes a reflection of the presence and abundance of introduced browsing mammals. It is a relatively short-lived (less than 50 years), slow-growing species with a fleshy fruit adapted to bird dispersal, but seed dispersal now appears to be primarily by gravity. Flowering occurs early in spring and is synchronous at both individual and population levels, occurring over a 5-week period, with peak flowering during the second and third weeks. While all populations set seed, reproductive output can be negatively affected by persistent browse and by rain during peak flowering. This species is vulnerable because it is highly palatable to introduced mammals and all plants in a population are within browse height. It has relatively narrow habitat specificity, localised distribution, and limited potential to extend its range. We suggest it fulfils the requirements of the category "declining", using the most recent classification of threatened and uncommon plants of New Zealand
Granulomatous meningoencephalomyelitis in dogs: A review
<p/> <p>Granulomatous meningoencephalomyelitis (GME) is an inflammatory disease of the central nervous system in dogs that is characterised by focal or disseminated granulomatous lesions within the brain and/or spinal cord, non-suppurative meningitis and perivascular mononuclear cuffing. The aetiology of the disease remains unknown, although an immune-mediated cause is suspected. This article reviewed the typical history, clinical signs and pathology of the condition along with current opinions on pathogenesis. The potential differential diagnoses for the disease were discussed along with current treatment options.</p
Investigating the Andromeda Stream: II. Orbital Fits and Properties of the Progenitor
We construct test-particle orbits and simple N-body models that match the
properties of the giant stellar stream observed to the south of M31, using the
model of M31's potential derived in the companion paper by Geehan et al.
(2006). We introduce a simple approximation to account for the difference in
position between the stream and the orbit of the progenitor; this significantly
affects the best-fitting orbits. The progenitor orbits we derive have orbital
apocenter \sim 60 \kpc and pericenter \sim 3 \kpc, though these quantities
vary somewhat with the current orbital phase of the progenitor which is as yet
unknown. Our best combined fit to the stream and galaxy properties implies a
mass within 125 kpc of M31 of (7.4 \pm 1.2) \times 10^{11} \Msun. Based on
its length, width, luminosity, and velocity dispersion, we conclude that the
stream originates from a progenitor satellite with mass M_s \sim 10^9 \Msun,
and at most modest amounts of dark matter; the estimate of is again
correlated with the phase of the progenitor. M31 displays a large number of
faint features in its inner halo which may be progenitors or continuations of
the stream. While the orbital fits are not constrained enough for us to
conclusively identify the progenitor, we can identify several plausible
candidates, of which a feature in the planetary nebula distribution found by
Merrett et al. is the most plausible, and rule out several others. We make
predictions for the kinematic properties of the successful candidates. These
may aid in observational identification of the progenitor object, which would
greatly constrain the allowed models of the stream.Comment: 17 pages, 10 color figures, 4 tables. Accepted by Monthly Notices;
some minor revisions and corrected typo
Graded junction termination extensions for electronic devices
A graded junction termination extension in a silicon carbide (SiC) semiconductor device and method of its fabrication using ion implementation techniques is provided for high power devices. The properties of silicon carbide (SiC) make this wide band gap semiconductor a promising material for high power devices. This potential is demonstrated in various devices such as p-n diodes, Schottky diodes, bipolar junction transistors, thyristors, etc. These devices require adequate and affordable termination techniques to reduce leakage current and increase breakdown voltage in order to maximize power handling capabilities. The graded junction termination extension disclosed is effective, self-aligned, and simplifies the implementation process
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