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Taxonomy and ecology of Mentzelia mollis Peck and related species
A study was made to clarify the relationships of Mentzelia mollis
Peck and two poorly understood taxa of Mentzelia (Loasaceae) to the
other members of the genus, its sections, and its subsections, and
to describe the general ecology of each taxon.
Within the genus, the section Trachyphytum is characterized by
pendulous seeds, an annual habit, and placentae that do not expand
as the seeds mature. The section is further divided into three subsections
on the basis of width of filaments and shape and surface
texture of the seeds.
Seven populations of M. mollis were found, all growing in a
floristically depauperate community on greenish clay derived from the
Sucker Creek Formation and all within the Succor Creek drainage of
Malheur County, Oregon and Owyhee County, Idaho. The Leslie
Gulch Mentzelia occurs only in Leslie Gulch, west of Succor Creek,
at the base of talus slopes of the same Sucker Creek Formation.
The Colorado Mentzelia has been found only in Colorado and Utah,
near the border between the two states.
Morphological and cytological comparisons of M. mollis and
the Leslie Gulch Mentzelia show differences in floral structure,
branching pattern, leaf shape, seed size and shape, and ploidy level.
Mentzelia mollis is a tetraploid (n=18) and the Leslie Gulch Mentzelia
is an octoploid (n=36). Both have narrow filaments, pendulous seeds,
and placentae which do not expand as the seeds mature. Comparison
of the Colorado Mentzelia with M. mollis shows similar branching
pattern and seed size, but differences in the seed surface detail and
in floral structure. The scanning electron microscope was utilized
to compare seed shape and surface detail of these three taxa with
that of three other species of section Trachyphytum.
Both M. mollis and the Leslie Gulch Mentzelia have flowers
which open about 2:30 p.m. and close after dark, and both are visited
by the same Bombyliid-type insects in early evening. Both tolerate
extraordinarily high concentrations of potassium, sodium, and
calcium, as well as high soil surface and air temperatures.
Placement of all three taxa in section Trachyphytum was made
on the basis of relative placental growth and annual habit. Seed shape
and surface detail justified their placement in subsection Trachyphyta.
Morphological considerations and ploidy level seemed sufficient evidence to describe the Leslie Gulch Mentzelia as a new species,
Mentzelia packardiae Glad; and morphological differences and geographical
separation indicated that the Colorado Mentzelia should be
similarly handled. It was described as Mentzelia thompsonii Glad.
An existing key was adapted to include all three species.
Speculation concerning possible origins of M. mollis and M.
packardiae leads to the hypothesis that M. mollis is a relic which
survived the climatic and geological fluctuations of the past. Its
origin is considered in relation to its being a member of a mature
polyploid complex. It is also considered possible that there may be
some relationship between M. mollis and the possibly younger M
packardiae. Both species are edaphic endemics, and their evolution
is briefly considered in that respect
Meandering river deposits in sediment cores, the Middle Jurassic Alma Field, Southern Danish Central Graben
Episodes of aeolian sand movement on a large spit system (Skagen Odde, Denmark) and North Atlantic storminess during the Little Ice Age
Optometric extension program: 1991 bibliography of near lenses and vision training research
Optometric extension program: 1991 bibliography of near lenses and vision training researc
Chaotic Observer-based Synchronization Under Information Constraints
Limit possibilities of observer-based synchronization systems under
information constraints (limited information capacity of the coupling channel)
are evaluated. We give theoretical analysis for multi-dimensional
drive-response systems represented in the Lurie form (linear part plus
nonlinearity depending only on measurable outputs). It is shown that the upper
bound of the limit synchronization error (LSE) is proportional to the upper
bound of the transmission error. As a consequence, the upper and lower bounds
of LSE are proportional to the maximum rate of the coupling signal and
inversely proportional to the information transmission rate (channel capacity).
Optimality of the binary coding for coders with one-step memory is established.
The results are applied to synchronization of two chaotic Chua systems coupled
via a channel with limited capacity.Comment: 7 pages, 6 figures, 27 reference
Treatment of intracerebral haemorrhage with tranexamic acid : A review of current evidence and ongoing trials
Peer reviewe
Thomas Decomposition and Nonlinear Control Systems
This paper applies the Thomas decomposition technique to nonlinear control
systems, in particular to the study of the dependence of the system behavior on
parameters. Thomas' algorithm is a symbolic method which splits a given system
of nonlinear partial differential equations into a finite family of so-called
simple systems which are formally integrable and define a partition of the
solution set of the original differential system. Different simple systems of a
Thomas decomposition describe different structural behavior of the control
system in general. The paper gives an introduction to the Thomas decomposition
method and shows how notions such as invertibility, observability and flat
outputs can be studied. A Maple implementation of Thomas' algorithm is used to
illustrate the techniques on explicit examples
Characterisation of CART-containing neurons and cells in the porcine pancreas, gastro-intestinal tract, adrenal and thyroid glands
<p>Abstract</p> <p>Background</p> <p>The peptide CART is widely expressed in central and peripheral neurons, as well as in endocrine cells. Known peripheral sites of expression include the gastrointestinal (GI) tract, the pancreas, and the adrenal glands. In rodent pancreas CART is expressed both in islet endocrine cells and in nerve fibers, some of which innervate the islets. Recent data show that CART is a regulator of islet hormone secretion, and that CART null mutant mice have islet dysfunction. CART also effects GI motility, mainly via central routes. In addition, CART participates in the regulation of the hypothalamus-pituitary-adrenal-axis. We investigated CART expression in porcine pancreas, GI-tract, adrenal glands, and thyroid gland using immunocytochemistry.</p> <p>Results</p> <p>CART immunoreactive (IR) nerve cell bodies and fibers were numerous in pancreatic and enteric ganglia. The majority of these were also VIP IR. The finding of intrinsic CART containing neurons indicates that pancreatic and GI CART IR nerve fibers have an intrinsic origin. No CART IR endocrine cells were detected in the pancreas or in the GI tract. The adrenal medulla harboured numerous CART IR endocrine cells, most of which were adrenaline producing. In addition CART IR fibers were frequently seen in the adrenal cortex and capsule. The capsule also contained CART IR nerve cell bodies. The majority of the adrenal CART IR neuronal elements were also VIP IR. CART IR was also seen in a substantial proportion of the C-cells in the thyroid gland. The majority of these cells were also somatostatin IR, and/or 5-HT IR, and/or VIP IR.</p> <p>Conclusion</p> <p>CART is a major neuropeptide in intrinsic neurons of the porcine GI-tract and pancreas, a major constituent of adrenaline producing adrenomedullary cells, and a novel peptide of the thyroid C-cells. CART is suggested to be a regulatory peptide in the porcine pancreas, GI-tract, adrenal gland and thyroid.</p
A sonographic spectrum of psoriatic arthritis: âthe five targetsâ
Ultrasound is a rapidly evolving technique that is gaining an increasing success in the assessment of psoriatic arthritis. Most of the studies have been aimed at investigating its ability in the assessment of joints, tendons, and entheses in psoriatic arthritis patients. Less attention has been paid to demonstrate the potential of ultrasound in the evaluation of skin and nail. The aim of this pictorial essay was to show the main high-frequency grayscale and power Doppler ultrasound findings in patients with psoriatic arthritis at joint, tendon, enthesis, skin, and nail level
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