Hook-shaped opal phytoliths in the epidermal cells of oats

1960 ◽  
Vol 8 (1) ◽  
pp. 69 ◽  
Author(s):  
G Baker
Keyword(s):  
Avena Sativa ◽  
Epidermal Cells ◽  
Solid Core ◽  
Growth Season ◽  
Opal Phytoliths ◽  
Central Victoria ◽  
The Core ◽  
South Central ◽  
Accumulator Plant ◽  
Shape And Size

Among several species of the Gramineae, Avena sativa L. (oats) is an important opal-accumulator plant in Victoria. In it, amorphous silica has been precipitated as very abundant microscopic opal phytoliths of various shapes, among which hook-shaped forms are common in alternating rows of epidermal cells. Examples studied in detail were observed within and isolatd from oats grown on basaltic soil on "Barewood Farm", approximately 2 miles north of Clarkefield in the Romsey district of South Central Victoria. They are variable in shape and size, and in their relationships to adjacent rod-like opal phytoliths that infill the lumen of several of the subepidermal cells. Each hook-shaped opal phytolith consists typically of a solid core of opal enveloped distally by a more delicate cone-like sheath of opal. The opal of the sheath is hyaline and transparent compared with the thicker, generally translucent core. Refractive index variations reveal differences between core and sheath, and between the several growth layers of slightly different composition in the sheath. These differences reflect variable ratios of silica to water in the opal of the core, the sheath, and its several layers. The hook-shaped opal phytoliths, like all other shape types secreted in short-lived plants, must have developed rapidly, because processes of opal precipitation and solidification were completed within the compass of one growth season.

Anatomy of two species of Plumbago : a traditional medicinal plant and its relevance for taxonomy

2021 ◽  
Vol 27 (2) ◽  
Author(s):  
Smita Chaudhari
Keyword(s):  
Medicinal Plant ◽  
Anatomical Study ◽  
Diagnostic Value ◽  
Epidermal Cells ◽  
Vascular Bundles ◽  
Taxonomic Significance ◽  
Anatomical Features ◽  
Leaf Petiole ◽  
Abundance And Distribution ◽  
Shape And Size

Plumbago is a traditional medicinal plant in Ayurveda. The paper presents anatomical study of leaf, petiole, stem and root of two species of Plumbago namely P. zeylanica, P. auriculata and, its relevance in discrimination of these two species. Anatomical features of leaf which are of diagnostic value in delimitation of both taxa are outline of T. S.,shape and size of epidermal cells, presence of sclerenchyma surrounding the vascular bundles, number of tannins cells. Characters of taxonomic significance in petiole anatomy are outline of T. S, presence of trichomes, shape and size of epidermal cells, abundance of collenchyma, arrangement and number of vascular bundles, presence of sclerenchyma surrounding vascular bundles, number of tannin cells. The diagnostically useful anatomical features of stem to discriminate both taxa of Plumbago are degree of elevation of stem ridges, occurrence of double layered epidermis, size of epidermal cells, distinctness of endodermis, abundance and distribution of pericyclicsclerenchyama, number of vascular bundles. Anatomical features of taxonomic significance in root are width of cortex and abundance of starch grains in cortex cells, abundance and distribution of pericyclics clerenchyama, amount of vascularization, distribution, diameter and density of vessels, width of medullary ray.

Evolution of the Slocan Syncline in south-central British Columbia

1968 ◽  
Vol 5 (4) ◽  
pp. 851-872 ◽  
Author(s):  
John V. Ross ◽  
P. Kellerhals
Keyword(s):  
British Columbia ◽  
Phase 1 ◽  
Granite Gneiss ◽  
Phase 2 ◽  
Phase 3 ◽  
The Core ◽  
South Central ◽  
Deformation Phase ◽  
Facies Metamorphism ◽  
The One

The Slocan Syncline, located in the center of the Kootenay Arc, south-central British Columbia, is outlined in its core by deformed Triassic sediments—the Slocan Group. These deformed sediments were originally deposited unconformably into a synform developed on the upward-facing limb of a recumbent, eastward-closing anticline, comprising Paleozoic and older rocks.The first phase of deformation resulted in the development of a recumbent anticline closing to the east. This anticline involved a sequence of rocks ranging in age from Windermere (late Precambrian—Horsethief Creek Group) up to Permian (Milford Group) and was originally developed along almost horizontal axes contained in an axial-plane having a shallow westerly dip. The core of this anticline contains granite gneiss, having a history pre-dating the deposition of the Horsethief Creek Group, which is in imbricate relation with the gneiss.Later, phase 2 deformation refolded this recumbent anticline into a synform and a westerly complementary antiform along shallow southeasterly axes contained within axial planes dipping southwesterly at about 45 degrees. Amphibolite-facies metamorphism (the "Shuswap Metamorphism") accompanied these phases of deformation and culminated in phase 2 time. Phase 1 and phase 2 deformation and metamorphism ate dated at post-Milford Group (Permian) and pre-Slocan Group (Triassic).Slocan Group (Triassic) sediments were deposited into the phase 2 synform, whose limbs consist of variable older rocks. A later non-metamorphic deformation, phase 3, along southeasterly striking axial planes dipping steeply to the northeast tightened the earlier phase 1 anticline and the phase 2 synform, and produced the Slocan Syncline. The Triassic sediments exhibit only phase 3 structures and are cut by the Nelson batholith dated at 171 × 106 years (Early Jurassic). Phase 3 deformation is then dated at post-Triassic and pre-Early Jurassic.Structural and stratigraphic evidence suggests that the phase 1 recumbent anticline herein described is but one of a set of nappes disposed structurally above and below the one presently described, and that the Kootenay Arc is an old structure perhaps resulting from interference of phase 1 and phase 2 deformations.

scholarly journals Quantum Crystals in Neutron Stars

1974 ◽  
Vol 53 ◽  
pp. 133-150 ◽  
Author(s):  
V. Canuto ◽  
S. M. Chitre
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Solid Core ◽  
Many Body ◽  
The Core ◽  
Deep Interior ◽  
Body Techniques ◽  
Quantum Crystals ◽  
The Many ◽  
Orderly Arrangement

Using the many-body techniques appropriate for quantum crystals it is shown that the deep interior of a neutron star is most likely an orderly arrangement of neutrons, protons and hyperons forming a solid. It is shown that a liquid or gas arrangement would produce higher energy. If so, a neutron star can be viewed as two solids (crust and core) permeated by a layer of ordinary or (perhaps) superfluid liquid. Astronomical evidence is in favor of such a structure: the sudden jumps in the periods of the Crab and Vela pulsars that differ by a factor of ∼ 102 can be easily explained by the star-quake model. If the Crab is less massive than Vela (i.e., if it is not dense enough to have a solid core), the star-quakes take place in the crust whereas for Vela they occur in the core.

THE SOLIDITY AND NONSOLIDITY OF INITIAL SEGMENTS OF THE CORE MODEL

2018 ◽  
Vol 83 (3) ◽  
pp. 920-938
Author(s):  
GUNTER FUCHS ◽  
RALF SCHINDLER
Keyword(s):  
Core Model ◽  
Solid Core ◽  
The Core ◽  
Inner Model ◽  
Cohen Real ◽  
Image Position ◽  
Woodin Cardinal

AbstractIt is shown that $K|{\omega _1}$ need not be solid in the sense previously introduced by the authors: it is consistent that there is no inner model with a Woodin cardinal yet there is an inner model W and a Cohen real x over W such that $K|{\omega _1}\,\, \in \,\,W[x] \setminus W$. However, if ${0^{\rm{\P}}}$ does not exist and $\kappa \ge {\omega _2}$ is a cardinal, then $K|\kappa$ is solid. We draw the conclusion that solidity is not forcing absolute in general, and that under the assumption of $\neg {0^{\rm{\P}}}$, the core model is contained in the solid core, previously introduced by the authors.It is also shown, assuming ${0^{\rm{\P}}}$ does not exist, that if there is a forcing that preserves ${\omega _1}$, forces that every real has a sharp, and increases $\delta _2^1$, then ${\omega _1}$ is measurable in K.

scholarly journals The fate of planetary cores in giant and ice-giant planets

2019 ◽  
Vol 631 ◽  
pp. L4 ◽  
Author(s):  
S. Mazevet ◽  
R. Musella ◽  
F. Guyot
Keyword(s):  
High Pressure ◽  
Ab Initio ◽  
Inner Core ◽  
Giant Planets ◽  
Ab Initio Molecular Dynamics ◽  
Solid Core ◽  
Potential Core ◽  
Melting Temperatures ◽  
The Core ◽  
Pressure Melting

Context. The Juno probe that currently orbits Jupiter measures its gravitational moments with great accuracy. Preliminary results suggest that the core of the planet may be eroded. While great attention has been paid to the material properties of elements constituting the envelope, little is known about those that constitute the core. This situation clutters our interpretation the Juno data and modeling of giant planets and exoplanets in general. Aims. We calculate the high-pressure melting temperatures of three potential components of the cores of giant planets, water, iron, and a simple silicate, MgSiO3, to investigate the state of the deep inner core. Methods. We used ab initio molecular dynamics simulations to calculate the high-pressure melting temperatures of the three potential core components. The planetary adiabats were obtained by solving the hydrostatic equations in a three-layer model adjusted to reproduce the measured gravitational moments. Recently developed ab initio equations of state were used for the envelope and the core. Results. We find that the cores of the giant and ice-giant planets of the solar system differ because the pressure–temperature conditions encountered in each object correspond to different regions of the phase diagrams. For Jupiter and Saturn, the results are compatible with a diffuse core and mixing of a significant fraction of metallic elements in the envelope, leading to a convective and/or a double-diffusion regime. We also find that their solid cores vary in nature and size throughout the lifetimes of these planets. The solid cores of the two giant planets are not primordial and nucleate and grow as the planets cool. We estimate that the solid core of Jupiter is 3 Gyr old and that of Saturn is 1.5 Gyr old. The situation is less extreme for Uranus and Neptune, whose cores are only partially melted. Conclusions. To model Jupiter, the time evolution of the interior structure of the giant planets and exoplanets in general, their luminosity, and the evolution of the tidal effects over their lifetimes, the core should be considered as crystallizing and growing rather than gradually mixing into the envelope due to the solubility of its components.

Geographical Elements in the Flora of Victoria

1976 ◽  
Vol 24 (2) ◽  
pp. 249 ◽  
Author(s):  
PB Bridgewater
Keyword(s):  
Plant Communities ◽  
Vascular Plants ◽  
Distribution Data ◽  
Inverse Association ◽  
Central Victoria ◽  
South Central ◽  
Southern Half ◽  
Species Groups ◽  
Geographical Elements ◽  
Very High

Distribution data for vascular plants in Victoria were recorded on grid squares of 1° latitude by 1.5° longitude. Data for six angiosperm families (Cyperaceae, Liliaceae, Chenopodiaceae, Rhamnaceae, Rutaceae and Myrtaceae) were analysed by the techniques of normal and inverse association analysis. Analyses of the data produced a series of species groups with similar geographical ranges (elements). These elements may be broadly divided into eastern and western groups, with two exceptions-one extending over the southern half of the State and the other occupying the coastal fringe. Geographical elements are helpful in defining the range of plant communities, as well as suggesting hypotheses as to the origins of floras. South central Victoria is seen to be a junction for species of both the eastern and western groups of elements, which may explain the very high number of species recorded from the Melbourne region.

High Birefringence Photonic Crystal Fibers

2010 ◽  
Vol 663-665 ◽  
pp. 713-716
Author(s):  
Shu Qin Guo ◽  
Min Ge ◽  
Pan Zhuang ◽  
Li Ping Chang
Keyword(s):  
Photonic Crystal ◽  
Solid Core ◽  
Crystal Fiber ◽  
The Core ◽  
Crystal Fibers ◽  
Section Structure ◽  
General Section ◽  
Birefringence Effect ◽  
Modal Field ◽  
Air Hole

Photonic crystal fiber (PCFs) offer new possibilities of realizing highly birefringence fibers due to a higher intrinsic index contrast compared to conventional fibers. Here, based on general section structure of PCFs, we take some mend in the core configuration, and achieve highly birefringence effect. A elliptic air hole and its inscribed circular high refractive material form the core of PCFs together. Especially to mention, they are being tangent at two points. By optimally selecting parameters, the effective refractive index difference between two orthogonal directions neff can reach the magnitude of 10-2. After numerical calculation, we find that increase the size of circular solid core, or long axe size of elliptic air hole, birefringence parameter of modal field can become more highly. Moreover, by matching structure parameters appropriately, the modal field diameters can be equivalent in the two orthogonal directions. A Gaussian modal field with highly birefringence character can be acquired.

scholarly journals Dynamical stability of giant planets: the critical adiabatic index in the presence of a solid core

2021 ◽  
Vol 507 (4) ◽  
pp. 6215-6224
Author(s):  
Suman Kumar Kundu ◽  
Eric R Coughlin ◽  
Andrew N Youdin ◽  
Philip J Armitage
Keyword(s):  
Incompressible Fluid ◽  
Giant Planets ◽  
Adiabatic Index ◽  
Dynamical Instability ◽  
Solid Core ◽  
Dominant Effect ◽  
Instability Strip ◽  
The Core ◽  
Core Accretion ◽  
Upper Boundary

ABSTRACT The dissociation and ionization of hydrogen, during the formation of giant planets via core accretion, reduce the effective adiabatic index γ of the gas and could trigger dynamical instability. We generalize the analysis of Chandrasekhar, who determined that the threshold for instability of a self-gravitating hydrostatic body lies at γ = 4/3, to account for the presence of a planetary core, which we model as an incompressible fluid. We show that the dominant effect of the core is to stabilize the envelope to radial perturbations, in some cases completely (i.e. for all γ > 1). When instability is possible, unstable planetary configurations occupy a strip of γ values whose upper boundary falls below γ = 4/3. Fiducial evolutionary tracks of giant planets forming through core accretion appear unlikely to cross the dynamical instability strip that we define.

scholarly journals Adapting a solid accretion scenario for migrating planets in fargo3d

2019 ◽  
Vol 490 (2) ◽  
pp. 2336-2346
Author(s):  
L A DePaula ◽  
T A Michtchenko ◽  
P A Sousa-Silva
Keyword(s):  
Time Scale ◽  
Accretion Rate ◽  
Critical Mass ◽  
Numerical Approach ◽  
Solid Core ◽  
Planetary Formation ◽  
Stellar Envelope ◽  
The Core ◽  
Planetary Migration ◽  
Gas Accretion

ABSTRACT In this work, we adapt a module for planetary formation within the hydrodynamic code fargo3d. Planetary formation is modelled by a solid core accretion scenario, with the core growing in oligarchic regime. The initial superficial density of planetesimals is proportional to the initial superficial density of gas in the disc. We include a numerical approach to describe the evolution of the eccentricity and the inclination of planetesimals during the formation. This approach impacts directly on the accretion rate of solids. When the core reaches a critical mass, gas accretion begins, following the original fargo scheme adapted to the fargo3d code. To exemplify how the module for planetary formation can be used, we investigate the migration of a planet in a 2D, locally isothermal gas disc with a prescribed accretion rate, analysing the time-scale involved in the planetary migration process along with the time-scale for planetary formation. The analysis reveals that the mass of the nucleus must be close to its critical value when crossing the ice line to avoid the planet’s fall into the stellar envelope. This will allow enough time for the planet to initiate runaway gas accretion, leading to a rapid mass increase and entering type II planetary migration.

The Litoria ewingi Complex (Anura:Hylidae) in South-Eastern Australia VIII.* Hybridization between L. ewingi and L. verreauxi alpina in the Mount Baw Baw Area, South Central Victoria

1985 ◽  
Vol 33 (2) ◽  
pp. 143 ◽  
Author(s):  
GF Watson ◽  
MJ Littlejohn ◽  
DF Gartside ◽  
JJ Loftus-Hills
Keyword(s):  
Northern Slope ◽  
Blood Proteins ◽  
Genetic Compatibility ◽  
Hybrid Swarm ◽  
Geographic Ranges ◽  
Central Victoria ◽  
South Central ◽  
Eastern Australia ◽  
High Level

Contacts between the geographic ranges of the widely distributed species, Litoria ewingi, and the montane-adapted taxon, L. verreauxi alpina, occur at about 1200 m on the Great Dividing Range in south central Victoria. Data for adult morphology, genetic compatibility, blood proteins (haemoglobins and transferrins), and structure of male advertisement calls, were obtained from seven populations at altitudes between 640 m and 1450 m in the region of the Mount Baw Baw Plateau. The results indicate that hybrids are present at intermediate altitudes (1140-1270 m), but that the nature of the interaction differs between overlap of parental taxa together with recombination products on the south-westem slope (the Baw Baw transect), and a hybrid swarm on the northern slope of the Mount Baw Baw plateau. Results of in vitro crosses (female L, ewingi by male L. v. alpina) indicate that there is a high level of genetic compatibility between the taxa. Estimates of the width of the hybrid zone on the Baw Baw transect vary from less than 4 km for morphology and calls, to between 10 and 24 km for blood proteins.

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