Opposite Branches Research Articles

AGE STRUCTURE DYNAMICS OF EUPATORIUM ADENOPHORUM POPULATIONS AND ITS IMPLICATIONS FOR CONTROL

The invasion of Eupatorium adenophorum has caused serious damage to natural ecosystems by suppressing native species populations in disturbed forests and pastures in southwest China. In this study, the age structure dynamics of E. adenophorum populations were examined in 20 plots (10 m × 10 m) using the Greig-Smith grid method, in Panzhihua Prefecture, Sichuan Province of China. There is no standard method for identifying the age of an E. adenophorum plants, but through careful observations of the growth characteristics of E. adenophorum over several years in Panzhihua, we found a reliable method for aging individual plants. During the coldest season of every year, the apical half of branches grown in the current year wither and die, and a pair of opposite branches expand out from the lignified half that is below the wilted top. Although it can turn out clone genet alone once the branch touches the ground. At the same time sexual propagation and vegetative reproduction of radicicolous branches carry through from year to year. That is to say, the most number of branching ranks of the same branch is likely to indicate the real age of the plant. We dug out the entire plant in each grid and counted the grade rank of each branch to determine the age of each individual plant. The results showed that the age structure of the 4 populations were similar with most individuals in the infancy (92.3%) and youth (6.4%) periods. The analysis of life tables and survival curves showed that chronological sequence of an E. adenophorum invasion was as follows: first, invasion occurred along roadside fields, followed by invasion into the margins of broad-leaved forest, then deep into broad-leaved forest, and finally into Pinus yunnanensis forest. Even under different environmental conditions, survival curves of all E. adenophorum populations belonged to the Deevey type Ⅲ pattern, and mortality of all populations showed a peak in 1-2 years old with mortality rates of 97.3%. The degree to which a population deviated from a typical curve related to the intensity of human disturbance. In general, mortality during infancy period and mature period were high (93.1% and 92.0%). The invasion time-sequence model predicts that young and mature individuals will dominate the populations at 3 and 5 years from the present. Therefore, in the Panzhihua Prefecture, we predict that E. adenophorum will become a serious problem in 3 to 5 years. Compared with populations of other invasive plants, the population of E. adenophorum has a similar break out pattern among populations. Traits promoting weediness included the ability to reproduce sexually and asexually, rapid growth from seedling to sexual maturity, and, most importantly, adaptation to environmental stress (phenotypic plasticity) and high tolerance to environmental heterogeneity.

Quantized adiabatic charge pumping and resonant transmission

Adiabatically pumped charge, carried by non-interacting electrons through a quantum dot in a turnstile geometry, is studied as function of the strength of the two modulating potentials (related to the conductances of the two point-contacts to the leads) and of the phase shift between them. It is shown that the magnitude and sign of the pumped charge are determined by the relative position and orientation of the closed contour traversed by the system in the parameter plane, and the transmission peaks (or resonances) in that plane. Integer values (in units of the electronic charge $e$) of the pumped charge (per modulation period) are achieved when a transmission peak falls inside the pumping contour. The integer value is given by the winding number of the pumping contour: double winding in the same direction gives a charge of 2, while winding around two opposite branches of the transmission peaks or winding in opposite directions can give a charge close to zero.

IDENTIFICATION OF VOLTAGE-CURRENT OPERATORS SATISFYING TELLEGEN'S THEOREM

Let [Formula: see text] be a directed nonseparable network composed of a finite set ℬ of branches and F(u,i), an operator defined on the set of all ordered pairs of voltages and currents. It is proved that, if [Formula: see text] is neither a cutset nor a loop, and contains both a loop and a cutset with unequal numbers of opposite directed branches, and [Formula: see text] for all branch voltages [Formula: see text] and currents [Formula: see text] satisfying Kirchhoff's voltage and current laws respectively in every loop and cutset of [Formula: see text], then F is biadditive. This substantially strengthens an old theorem of Kishi and Kida in which, [Formula: see text] was allowed to vary over the set of all networks and physically reveals that the power is essentially the only continuous voltage-current operator which, when associated with a branch, yields Tellegen's famous theorem. It is also proved that, conversely, if F is biadditive, then the above sum is zero for an arbitrary network [Formula: see text]. The topological assumptions imposed on [Formula: see text] are thoroughly examined and shown to be necessary. Finally, similar analytic characterizations of eulerian and bipartite networks, respectively in terms of voltage and current operators with zero sums of values over all network branches are given.

Morphology, anatomy and reproduction of the eastern Mediterranean coralline Tenarea tortuosa and its relationship to members of the Lithophylloideae and Mastophoroideae (Rhodophyta, Corallinales)

One of the most characteristic organisms of the Mediterranean flora, the endemic coralline Tenarea tortuosa, has been collected along the Cretan coast and its vegetative and reproductive structures are reassessed. Gametophytes are described for the first time and are rare, observed only in one locality on the south coast. Reproductive structures suggest that the sexual life history is triphasic, but the present collections indicate unequal representation of males, carposporophytes and tetrasporophytes, and a dominance of bisporophytes suggesting that the alga is reproducing mainly asexually. The frond of Tenarea is formed by the coordinated growth of two elements (branches), growing back‐to‐back, each showing a simple Titanodema‐type of organization; i.e. a monostromatic hypothallium of sinuous cells and a single layer of obliquely borne epithallial cells. Contiguous cells of the two opposite branches are not connected by secondary pit‐plugs, and easily glide apart if decalcified. Natural splitting of the lamellae into its two branches may also occur, and single branches may fold regenerating the back‐to‐back organization. Analogous back‐to‐back growths occur in species of the distantly related genera Goniolithon (Lithophylloideae) and Leptophytum (Melobe‐sioideae) and apparently represent cases of convergence. The affinities of Tenarea to related genera are discussed.

Surface-profile dependence of photon-plasmon-polariton coupling at a corrugated silver surface

The influence of the surface-profile Fourier decomposition on photon–surface-plasmon-polariton (SPP) coupling at a corrugated silver surface, as probed by changes in diffraction-order intensities, line shapes, and peak positions, is explored. The effect of higher spatial harmonics on diffraction orders is considered for coupling to the SPP in the vicinity of a grating-induced minigap as well as away from the minigap region. Numerical results are obtained with the reduced Rayleigh equations, which are accurate in the range of corrugation strengths that optimize photon–SPP coupling for silver. Under first-order-coupling conditions away from the minigap region the presence of a particular spatial harmonic in the surface profile enhances a specific diffraction order in an easily predictable way. The selectivity, sensitivity, and associated line-shape changes for enhancement are examined as a function of harmonic amplitude for several higher harmonics. In connection with recent experiments [ J. Opt. Soc. Am. B8, 1348 ( 1991)] we investigate the influence of the second and the third spatial harmonics on the propagating orders in the vicinity of the (+ 1, −2) minigap region of an 870-nm grating at 633 nm. The interaction between first- and second-order couplings to the opposite branches of the SPP dispersion relation is tuned by variation of the corrugation depth. It is found that changes in the profile Fourier decomposition with corrugation depth, which arise in the holographic fabrication of diffraction gratings, can explain the observed momentum gap in the −1 diffraction order in this case.

Nonlocal theory of collective excitations in quantum-dot arrays.

We present a nonlocal theory of collective excitations in quantum-dot arrays. Selection rules, oscillator strengths, and Coulomb interactions inside a dot and between dots are discussed. The collective excitation energy is found to ``saturate'' for ${\mathit{n}}_{0}$ (the number of electrons per dot) greater than 3. The depolarization energy shift in a quantum-dot array is found to be predominantly due to interdot coupling. We explain qualitatively the multiple branches and anticrossings recently observed in far-infrared experiments. We predict that anticrossings can occur only if ${\mathit{n}}_{0}$>2. If ${\mathit{n}}_{0}$\ensuremath{\le}2, there should be only one branch with positive B dispersion, and one branch with negative B dispersion, where B represents a perpendicular magnetic field. Multiple branches with positive (negative) B dispersions occur for larger ${\mathit{n}}_{0}$. The use of left (right) -circularly-polarized light should result in signals predominantly from positive (negative) B dispersion branches, while signals from the opposite polarization branches should provide information on the coupling between positive and negative B dispersion branches.

Geoid anomalies over two South Atlantic fracture zones

Seasat altimetry profiles across the Falkland-Agulhas fracture zone (FZ) and the Ascension FZ in the South Atlantic were examined for evidence of step-like geoid offsets predicted from thermal modeling of the lithosphere. The geoid profiles exhibit much short-wavelength power and the step-like offsets are often small, making reliable estimation of the heights of the observed geoid offsets difficult. The offsets were estimated by the least-squares fitting of quadratic curves incorporating a step function to the altimetry profiles. A preferred offset value was determined for each profile by taking the average of step heights computed with various distances around the fracture zone excluded from the fit. The age of the crust surrounding the fracture zones, necessary for computing a theoretical geoid offset, was determined from surface ship magnetic anomaly data and from existing ocean floor age maps. Observed variations in geoid step height with age of the lithosphere are not consistent with those predicted from standard thermal plate models. For ages less than ∼ 30 Ma, the step offsets across both fracture zones decrease in a manner appropriate for an unusually thin plate with a thickness of 50–75 km. At greater ages, the offsets show complex behavior that may be due to bathymetric features adjacent to the fracture zones. Similar geoid patterns on opposite branches of the Falkland-Agulhas FZ are indicative of processes that act symmetrically on both sides of the Mid-Atlantic Ridge. This behavior of the geoid is consistent both with small-scale convection occurring beneath the lithosphere and with bathymetric features originally produced along the ridge crest and now located symmetrically on opposite sides of the ridge. The west flank of the Ascension FZ displays a regrowth in step height at about 40 Ma consistent with small-scale convection and in agreement with other studies of Pacific and South Atlantic fracture zones.

A New Filmy Fern from Puerto Rico

and margins of the blade. Blades oblong-lanceolate, 6-15 cm long, 2.5-3.5(5) cm broad, pinnate-pinnatifid, acuminate at the apex, subtruncate at the base; rhachis alate (wings 0.3-0.7 mm wide on either side); pinnae ascending, alternate, 7-13 on a side below the pinnatifid apex, 1.5-2.5 cm long, short-stalked (the stalks winged like the rhachis), the expanded portion rhombic-acuminate, 1-1.5 cm broad below the middle, deeply pinnatifid, the segments oblique, the largest ones narrowly oblong, obtuse, with lobed margins; costules of basal segments arising oppositely from costa, in turn with opposite or subopposite simple branches, each vein extending to the apex of a lobe. Sori numerous, apical on the lobes or smaller segments; involucres immersed, oblong-turbinate or turbinate, 1.7-2 mm long, the apex subtruncate to slightly flaring; receptacle becoming long-exserted.

The particle scattering factor of branched macromolecules: computer simulation

Theoretical prediction of the particle scattering factor I (ϑ) is possible for a limited number of molecular shapes (random coils, spheres, cylinders), which can be described in terms of distances only. Given the importance of branched macromolecules, where angles also play a role, we have devised a computer procedure for calculating the particle scattering factor. Scattering was simulated for trees with alternate and with opposite branches, with straight branches and with broken branches, 2-dimensional as well as 3-dimensional, and also for systems consisting of two trees acting as a single scatterer. To elucidate various factors affecting I (ϑ), several parameters were varied, including angles between trunks and branches, angles between two linear fragments of a broken branch, and densities of linear fragments. Light scattering by generalized trees consisting of unconnected segments has been discussed. For normal trees representing real molecules, procedures enabling considerable savings in computing times have been devised.

Some Effects of Ringing Branches on the Distribution of Dry Matter in Young Apple Trees

Young apple trees, variety Sunset/M.7, were prepared with two similar branches. Rings of bark and blossoms were removed from selected branches at full bloom to give the 10 possible combinations of ringed and unringed, deblossomed and cropping branches. Ringing led to improved fruit set and some reduction in vegetative growth above the ring. The best crops and least reduction of vegetative growth on ringed branches occurred where the second branch was unringed. Dry matter was deposited in the branches in proportion to the leaf area and was virtually independent of treatment. Additional dry matter was deposited as fruit, trunk thickening, and root growth. Dry matter production per unit area of associated leaf was increased on ringed branches by enhanced fruit set and on unringed branches by the isolation of leaves on opposite ringed branches from the leaves supplying the rootstock. Differences could not be detected in the carbohydrate composition of the growing regions as a result of treatment although alterations in demand could cause a three-fold difference in dry matter production per unit leaf area. This indicates an ability on the part of apple leaves to increase dry matter production in support of enhanced growth.

Species of the Subtribe Sevadinae (Chenopodiaceae)

Subtrib. Sevadinae Botsch. (Chenopodiaceae trib. Salsoleae C. A. Mey.) in Bot. Zhourn. 52: 8oo (x967). Low glabrous shrubs with alternate or opposite branches and leaves. Young branches smooth or sometimes papillous. Leaves smooth or sometimes papillous, fleshy, semiterete, clavate and obtuse or linear and acuminate, sometimes shortly pointed at the apex, slightly contracted above the base, at the base somewhat extended and decurrent, in the axil with a bundle of straight or flexuous hairs. Flowers in the axil of the bract with bracteoles, sessile, in clusters or solitary, forming an interrupted spike. Bracteoles shorter than perianth, herbaceous, with membranous margin, without hairs in the axil. Perianth connate in the lower part, in the upper part 5-dentate, in fruit slightly accrescent, at the base spongy and annular, without wings or with longitudinal membranous crests or transversal membranous wings, either I wing, ringlike, enclosing the perianth, or 5 incumbent wings. Stamens 5; filaments gradually tapering upwards, the bases of the filaments attached to the margin of the hypogynous disc; anthers elliptical or ovate, divided to the middle, with a compact minute appendage at the apex. Hypogynous disc patelliform with 5 thickened semicircular lobes. Stigmas 2, linear or lanceolate, acute, papillose on inner side, with short or rather long style. Seeds horizontal or vertical; pericarp membranous or indurated; embryo spiral.

Magnetic Fields in Polar Prominences

The results of longitudinal magnetic field measurements in polar prominences (PP), obtained by Rust during 1964–1965 and by the author during 1966, 1969 and 1970, are considered. The magnetic field configuration in PP is similar to that of an arc. In opposite branches of such an arc the magnetic field has different polarities that do not coincide with the magnetic field polarity in current cycle BMR's. The magnetic field value increases as the angle between the line of sight and filament long axis grows. PP's reflect the behaviour of the border line between the magnetic fields of preceding and current cycles.

CAROTID COMPRESSION DEVICE FOR THE PREVENTION OF RADIATION HAZARD.

For the comprehensive investigation of cerebrovascular diseases with the aid of angiography it has become increasingly necessary to demonstrate cerebral vessels in their entirety. This is achieved by a puncture of the internal or common carotid artery. Before and during the injection of the contrast medium the contralateral common carotid is usually compressed in the cervical region with the palpating hand. Diminished vascular pressure of the cerebral vessels is thereby produced at the compressed side and thus the injected contrast substance may fill the opposite arterial branches via the anterior communicating artery. In this particular procedure the examiner's hand performing the compression is exposed to the primary x-ray beam (Fig. 1). If in one examination an average of 6 exposures are made for the anteroposterior and half-axial view, and many times more in a seriogram, it is evident that in several examinations per day the radiation dose to the hand will accumulate considerably. Because of this a device has been developed which prevents primary radiation to the hand while compressing the carotid artery. Description and Operation of Device The existing compression device is based on the principle of sphygmomanometry. A rubber diaphragm (D1) is brought into contact with the patient, and a second diaphragm (D2) with a larger area provides sufficient displacement of air to utilize the full range of a manometer of the aneroid type (Fig. 3). The rubber membrane of the first diaphragm serves to pick up the pulsations of the carotid artery. The pulse is then transmitted to the second diaphragm whose pressure will be registered on the aneroid dial by a slight flicker of the indicator. With complete obliteration of the artery the flicker movement will cease, thereby indicating the systolic pressure. The instrument, attached to a removable metallic rod (Fig. 4), may be manually applied to the neck, with the hand holding the rod of the instrument behind the drawn lead curtain which is in front of the x-ray tube. The examiner's hand is thus removed from the primary x-ray beam (Fig. 2). Application of the Instrument The obliteration of the carotid artery occurs at the first diaphragm which has a steel ring frame 2 cm. in diameter. Pulsations are recorded on the dial by applying the instrument at random in the neck region. When the greatest amplitude is found on the dial the investigator knows that the diaphragm is directly positioned over the desired artery. The search for the best location of arterial compression may be facilitated by digital palpation; when the area of maximal pulsation is found, the palpating finger is then replaced by the instrument. With the diaphragm over the artery and increased manual pressure applied to the instrument the ring around the diaphragm will occlude the artery. It is important to ascertain that the artery is well fixed.

Genética de Coffea: XIX - Mutação somática afetando a côr das fôlhas em café

SUMMARY Somatic mutations usually found in Coffea arabica L. result in most cases from doubling or reduction in chromosome number. Gene instability in somatic tissues was reported for the na na and xc xc alleles which control, respectively, habit of growth and leaf size, and the color of the ripened fruits. No case of somatic instability of genes res­ponsible for the color of leaves has been reported previously. Young leaves of coffee plants are usually green or of a dark or light bronze color ; mature leaves are green. Leaves of plants of the variety purpurascens ( Coffea arabica L. var. purpurascens Cramer), however, present dark purple young leaves and slightly purple mature leaves. Purpurascens behaves as recessive to green. Among the progeny of a backcross (green x purpurascens) x purpurascens, a seedling was found that possessed normal green leaves except for two opposite branches arising from the same node. One of the branches was entirely purpurascens ; normal green and purpurascens areas could be seen in the mature leaves of the other. Since this plant had originally a non purpurascens phenotype, it should be a heterozygous