bluuebunny/crossref_metadata_2025 huggingface dataset:
Breakdown of a Locally Heated Liquid Film Shear-Driven in a Minichannel
Authors: Zaitsev D. V. , Kabov O. A.
Published: September 2008

The paper focuses upon shear-driven liquid film evaporative cooling of high-speed computer chips. Thin liquid films may provide very high heat transfer rates, however development of cooling system based on thin film technology requires significant advances in fundamental research. The paper presents new experimental data on flow and breakdown of a liquid film driven by the action of a forced gas flow in a horizontal minichannel (2 mm high), heated from a 22×6.55 mm heater. A map of isothermal flow regimes is plotted and the lengths of smooth region and region of 2D/3D wave occurrence are measured. The scenario of liquid film breakdown under heating is found to differ widely for different flow regimes. It is revealed that the critical heat flux at which film breakdown occurs for a shear-driven liquid film can be several times higher than that for a gravitationally-driven liquid film. This fact makes shear-driven liquid films very promising in high heat flux cooling applications.
Lattice Boltzmann Simulation of Surface Tension Dominated Vortices Behaviour in Two-Phase Mixing Layer
Authors: Yan Y. Y. , Zu Y. Q.
Published: September 2008

Surface tension dominating mixings and interfacial interactions are major phenomena of multiphase flow in microchannels and a variety of micro mixers. Such phenomena are concerned with interfacial interactions not only at fluid-solid interface but also at different fluids/phases interfaces. In this paper, vortices behaviours in a mixing layer of two immiscible fluids are studied numerically. The lattice Boltzmann method (LBM) is employed to simulat surface tension dominated mixing process. As a mesoscopic numerical method, the LBM has many advantages, which include the ability of incorporating microscopic interactions, the simplicity of programming and the nature of parallel algorithm and is therefore ideal for simulating multiphase flow. In this article, the index function methodology of the LBM is employed to simulate surface tension dominated vertices behaviour in a two-dimensional immiscible two-phase mixing layer. The initial interface between two-fluids is evenly distributed around the midpoint in vertical direction. Different velocity perturbations which consist of a basic wave and a series of sub-harmonic waves are forced at the entrance of a rectangular mixing layer of the flow field. By changing the strength of surface tension and the combinations of perturbation waves, the effects of the surface tension and the velocity perturbation on vortices merging are investigated. The vortices contours and frequency spectrums are used to analyse the mechanism of vortices merging. Some interesting phenomena, which do not take place in a single-phase mixing layer, are observed and the corresponding mechanism is discussed in details.
A Natural Convection DNA Amplifier
Authors: Daly John , Davies Mark
Published: September 2008

Natural convection is the driver of innumerable natural world phenomena. Within the laboratory, it offers simplified geometries and flow structures without the need for auxiliary flow inducement, thereby greatly reducing the risk of external contamination within biomedical applications. Outlined in this paper is a polymerase chain reaction (PCR) device which takes advantage of these distinct qualities. PCR has become synonymous with DNA amplification in molecular biology laboratories throughout the world, and at the heart of PCR is thermal cycling. Commonly PCR is accomplished utilising a three stage thermal cycle, however, the device presented employs an alternative two stage cycle which facilitates a simplified natural convection flow structure. The device is, in its fundamental design format, a well-based thermocycler with fast reaction times of 15 minutes. Through the use of Particle Image Velocimetry (PIV) and flow visualisation techniques, a better understanding of the flow structures and their effect on PCR is attained within a device of dimensions of 1 mm depth by 10mm width and 10mm height. This device may present an opportunity for the development of a practical and inexpensive single gene diagnostic tool. Presented here are the findings of the amplification of an 86-bp fragment of the pGEM®-T vector (Promega) within the convective flow loop.
Analysis of Microchannel Heat Sink Performance for Electronics Cooling Based on Thermodynamics
Authors: Abbassi Hessamoddin , Saidi Mohammad H. , Kazemi Pouya Zageneh
Published: September 2008

Present investigation analyzes the issue of entropy generation in a uniformly heated microchannel heat sink (MCHS). Analytical approach used to solve forced convection problem across MCHS, is porous medium model based on modified Darcy equation for fluid flow and two-equation model for heat transfer between solid and fluid phases. Furthermore, closed form solution of velocity distribution is employed to capture z-direction velocity gradient of flow, which plays a salient role on entropy generation through fluid flow. Analytical expressions for total and thermal entropy generation number (stems from heat transfer), and Bejan number are derived and cast into dimensionless form using velocity and temperature distributions. Besides, entropy generation characteristics in MCHS and the impact of various influential parameters on entropy production have been investigated. Finally, In order to examine the accuracy of analysis, the results of thermal evaluation are compared to one of the previous investigations conducted for thermal optimization of MCHS.
Deformation and Oscillations of a Single Gas Bubble Rising in a Narrow Vertical Tube
Authors: Wang Zhaoyuan , Tong Albert Y.
Published: September 2008

A single gas bubble rising in a narrow vertical tube is investigated via a numerical model on a 3-D axisymmetric computational domain. The transient governing equations are solved by a finite volume scheme with a two-step projection method. The interface between the liquid and gas phase is tracked by a coupled level set and volume-of-fluid (CLSVOF) method. A surface tension modeling method, which preserves the jump discontinuity of pressure at the interface, is employed. The flow structure and terminal velocity obtained in the numerical simulation are in excellent agreement with experimental measurements. Special attention is paid to the bubble oscillations during the initial stage of ascent. It has been found that the bubble bottom undergoes severe oscillations while the nose maintains a stable shape. A parametric study is performed to identify the factors controlling the oscillations at the bubble bottom.
Investigation of Fouling in Microchannels
Authors: Perry Jeffrey L. , Kandlikar Satish G.
Published: September 2008

Particulate fouling in microchannels is a subject that is largely unexplored. It does, however, have significant implications for all microchannel flows since the hydraulic diameters are very small and consequently are susceptible to excessively large pressure drops. The significant forces for dilute solutions of silica particles ranging from 3 to 10 μm are studied in rectangular microchannels made in silicon with a hydraulic diameter of 106 μm. The effects of zeta potential which is pH driven, lift force on the particulates and their fouling characteristics are evaluated by measuring the pressure drop across the microchannel test section.
Analysis of non-Newtonian power-law liquids with a weight-controlled capillary viscometer
Authors: Digilov Rafael M. , Gurfinkel B. , Reiner M.
Published: September 2008

We analyze the non-Newtonian behavior of a liquid draining under gravity from a tank through a capillary discharge tube and obtain an expression for the time variation of the weight of the liquid in the tank. As a result, a previously proposed weight-controlled capillary viscometer can be applied to both Newtonian and non-Newtonian liquids.
An audible demonstration of the speed of sound in bubbly liquids
Authors: Wilson Preston S. , Roy Ronald A.
Published: September 2008

The speed of sound in a bubbly liquid is strongly dependent upon the volume fraction of the gas phase, the bubble size distribution, and the frequency of the acoustic excitation. At sufficiently low frequencies, the speed of sound depends primarily on the gas volume fraction. This effect can be audibly demonstrated using a one-dimensional acoustic waveguide, in which the flow rate of air bubbles injected into a water-filled tube is varied by the user. The normal modes of the waveguide are excited by the sound of the bubbles being injected into the tube. As the flow rate is varied, the speed of sound varies as well, and hence, the resonance frequencies shift. This can be clearly heard through the use of an amplified hydrophone and the user can create aesthetically pleasing and even musical sounds. In addition, the apparatus can be used to verify a simple mathematical model known as Wood’s equation that relates the speed of sound of a bubbly liquid to its void fraction.
The conversion of phase to amplitude fluctuations of a light beam by an optical cavity
Authors: Villar Alessandro S.
Published: September 2008

Very low intensity and phase fluctuations are present in a bright light field such as a laser beam. These subtle quantum fluctuations may be used to encode quantum information. Although intensity is easily measured with common photodetectors, accessing the phase information requires interference experiments. We introduce one such technique, the rotation of the noise ellipse of light, which employs an optical cavity to achieve the conversion of phase to intensity fluctuations. We describe the quantum noise of light and how it can be manipulated by employing an optical resonance technique and compare it to similar techniques, such as Pound–Drever–Hall laser stabilization and homodyne detection.
The transverse traceless gauge and quadrupole sources
Authors: Price Richard H. , Wang Yan
Published: September 2008

A gravitational wave propagating in the +z direction is usually described by the transverse spatial components hxx, hyy, hxy in the transverse traceless gauge in which hxx+hyy=0. The transverse components are not changed by a gauge transformation, which implies that the traceless condition must be automatically met. We analyze how this comes about in the calculation of the waves in an explicit example, a circular binary orbit of equal mass points. This calculation is a useful exercise in linearized general relativity and gravitational waves, and a model of an important astrophysical source of detectable waves. We also demonstrate automatic transverse tracelessness for the general case of a slow motion source.
Differences between bouncing balls, springs, and rods
Authors: Cross Rod
Published: September 2008

When one hard steel ball collides with another, kinetic energy is conserved, even if the balls have different diameters. Why is kinetic energy conserved in such a collision, given that kinetic energy is not conserved when two unequal length steel springs or rods collide? Experimental results with bouncing balls, springs, and rods are presented, which reveal the answer. For colliding springs and rods a significant fraction of the initial kinetic energy is retained after the collision as vibrational energy in the longer spring and rod. When two hard balls collide, a negligible fraction of the initial energy is converted to vibrational energy because the collision time is much longer than the transit time of an acoustic wave across each ball due to the fact that the contact region of a hard spherical ball is much softer than the rest of the ball.
Statistical consequences of the zero-point energy of the harmonic oscillator
Authors: de la Peña Luis , Valdés-Hernández Andrea , Cetto Ana María
Published: September 2008

In a recent thermodynamic analysis of the harmonic oscillator Boyer has shown, using an interpolation procedure, that the existence of a zero-point energy leads to Planck’s law. We avoid the interpolation procedure by adding a statistical argument to arrive at Planck’s law as a consequence of the existence of the zero-point energy. As in Boyer’s argument, no explicit assumption of quantum mechanics is introduced. We discuss the relation of our results to the analysis of Planck and Einstein which led to the notion of the quantized radiation field. We then inquire into the discrete or continuous behavior of the energy and pinpoint the origin and meaning of the discontinuities. To include zero-point fluctuations (which are neglected in the thermodynamic analysis), we discuss the statistical (in contrast to the purely thermodynamic) description of the oscillator, which accounts for both the thermal and temperature-independent contributions to the dispersion of the energy.
A laboratory experiment to demonstrate Gauss’s law for electric fields
Authors: Donohoe J. Patrick
Published: September 2008

This paper describes an experiment that demonstrates Gauss’s law for electric fields. The experiment utilizes easily obtained equipment and requires simple electrostatic field measurements. The field measurements are obtained for azimuthally symmetric electrodes located over a conducting ground plane. The measurements are shown to be consistent with the image theory solution for a spherical electrode over a ground plane. The relation between Gauss’s law and the concept of capacitance is also demonstrated.
Making optical vortices with computer-generated holograms
Authors: Carpentier Alicia V. , Michinel Humberto , Salgueiro José R. , Olivieri David
Published: September 2008

An optical vortex is a screw dislocation in a light field that carries quantized orbital angular momentum and, due to cancellations of the twisting along the propagation axis, experiences zero intensity at its center. When viewed in a perpendicular plane along the propagation axis, the vortex appears as a dark region in the center surrounded by a bright concentric ring of light. We give detailed instructions for generating optical vortices and optical vortex structures by computer-generated holograms and describe various methods for manipulating the resulting structures.
Wigner functions and Weyl transforms for pedestrians
Authors: Case William B.
Published: September 2008

Wigner functions and Weyl transforms of operators offer a formulation of quantum mechanics that is equivalent to the standard approach given by the Schrödinger equation. We give a short introduction and emphasize features that give insight into the nature of quantum mechanics and its relation to classical physics. A careful discussion of the classical limit and its difficulties is also given. The discussion is self-contained and includes complete derivations of the results presented.
Studies on sunflower rust. VII. Effect of light and temperature during spore formation on the germinability of fresh and stored urediospores of Puccinia helianthi
Authors: Sood Praim N. , Sackston W. E.
Published: September 2008

Light intensity from 2200 to 43 000 lux during production of urediospores of Puccinia helianthi had little influence on germinability of fresh spores. The higher light intensities had an adverse effect on germinability of spores stored at −16 °C for 2 months. Daylength had little consistent effect on germinability of fresh or stored spores. Spores produced at day temperatures of 16, 21, and 27 °C showed no effect of temperature on germinability when fresh. After 2 months storage at −16 °C germination was highest for spores produced at 21°. Spores of races 1 and 3 germinated well after 1218 days of storage at −16°, and a small percentage germinated after storage at 4 °C. Races 2 and 4 germinated well after 1136 days storage at −16 and 4 °C. Races 2 and 4 survived longer than races 1 and 3 at 30° and at 23 °C, but not at 13 °C. Race 3 appeared more susceptible than race 1 to effects of light, temperature, and storage.
Budding and fine structure of Tremella mesenterica haplonts
Authors: Bandoni R. J. , Bisalputra A. A.
Published: September 2008

Budding and fine structure were examined in two compatible haploid strains of Tremella mesenterica. Budding is initiated at one pole; successive buds are developed at the initial site and at any subsequently formed sites. The budding process appears to combine features found in apiculate and non-apiculate ascosporogenous yeasts, and in Sporobolomyces and Rhodotorula. The fine structure observed suggests that new wall material might be deposited within cells as each successive bud is formed. No differences were observed in either structure or budding of the two mating strains examined.
Probable sites for passive movement of ions across the endodermis
Authors: Dumbroff E. B. , Peirson D. R.
Published: September 2008

The endodermis, with its associated Casparian strip, is generally believed to act as an effective barrier to the passive movement of ions from the cortex to the xylem in young roots. However, several workers have suggested that the functional integrity of the endodermis might be somewhat impaired with the emergence of branch roots from the pericycle, thus providing pathways for the mass flow of water and ions into the stele. The present work was undertaken to examine the validity of this hypothesis.Sections of lateral roots embedded in glycol methacrylate were stained and examined by fluorescence microscopy, and a general picture of the relationship between branch root development and concomitant changes in the endodermis emerged. The endodermal cells of the parent root were found to maintain a continuous, unbroken, suberized layer over the surface of a very young lateral root, but with continued elongation there is a period when formation of the Casparian strip lags behind division of endodermal cells. It appears likely that, at this stage, water and ions can enter the stele of the parent root by mass flow.
The origin of the ascogenous hyphae from pseudoparaphyses in Platyspora pentamera
Authors: Corlett Michael
Published: September 2008

The ascogenous hyphae and asci of Platyspora pentamera (Karst.) Wehm. arise from the lower cells of the pseudoparaphyses at the bottom of the ascocarp centrum. Ascospore development, showing the sequence of septation, is described and illustrated.
Response of cabbage root hairs to infection by Plasmodiophora brassicae
Authors: Williams P. H. , Aist Sheila J. , Aist J. R.
Published: September 2008

Cabbage root hairs provide a useful system for studying responses to infection by Plasmodiophora brassicae at the cellular level. Roots of cabbage seedlings grown in liquid culture were inoculated with zoospores of P. brassicae, and the effects of infection on host nucleolar development and root hair cell extension were studied. Within 18 h after the root hairs emerged from the trichoblasts the nucleoli of noninfected cells declined in diameter from 5 μ to less than 1 μ. Root hairs which became infected, whether 6 h old or 24 hold, had a nucleolar diameter ranging between 1.5 and 3 μ. The diameter of the nucleolus did not increase above 1.5–3 μ regardless of the age and number of Plasmodia within the cell. In addition to nucleolar enlargement, parasitized cells became stunted and often enlarged at their tips. Growth of Plasmodia within hair cells occurred with synchronous division of their nuclei. After penetration by the parasite there was an 18 h lag before the first nuclear division within the Plasmodia after which synchronous nuclear division occurred at about 4-h intervals.
Buds on the roots of Hieracium florentinum (hawkweed)
Authors: Peterson R. L. , Thomas A. G.
Published: September 2008

Hieracium florentinum All. reproduces vegetatively by adventitious buds which have been shown by anatomical studies to arise from roots. Culture experiments indicate that undamaged roots and isolated root tips have the capacity for bud initiation. Vegetative propagation by means of root-borne buds is important in the expansion of existing populations of H. florentinum.
In vitro germination and pollen tube growth of maize (Zea mays) pollen. IV. Effects of the fertility restoring Rf1 locus
Authors: Pfahler P. L.
Published: September 2008

Pollen grains from the near-isogenic inbreds, Oh 43 Rf1Rf1, Oh 43 rf1rf1, 106 Rf1Rf1, and 106 rf1rf1 were cultured on an artificial medium containing 15% sucrose and 0.6% bacto-agar supplemented with all possible combinations of two levels (0.00 and 0.03%) of calcium nitrate (Ca) and two levels (0.00 and 0.01%) of boric acid (B). At certain combinations of Ca and B, significant differences between the Rf1Rf1 and rf1rf1 genotypes were obtained for germination percentage, rupturing percentage, and pollen tube length. However, the effect of the Rf1 and rf1 alleles was not consistent in magnitude for both inbreds. Apparently, the Rf1 and rf1 alleles can alter certain in vitro germination characteristics but genetic background is also involved.
Effect of picloram on 14CO2-fixation and translocation of 14C-assimilates in Canada thistle, soybean, and corn
Authors: Sharma M. P. , Born W. H. Vanden
Published: September 2008

Photosynthetic 14CO2-fixation by excised leaves of Canada thistle (Cirsium arvense (L.) Scop.) and soybean (Glycine max (L.) Merr., cultivar Harosoy 63) was reduced significantly by prior exposure of the roots of source plants to 4-amino-3,5,6-trichloropicolinic acid (picloram) at 1, 10, or 20 ppm. At 10 ppm (0.036 mM) fixation was about half of that in corresponding controls. In corn (Zea mays L., cultivar Morden 77) no inhibition occurred at 10 ppm picloram but at 20 ppm the reduction in fixation (13%) was significant. The treatments had no marked effect on 14CO2-fixation in the dark. Treatments which caused 50% or more inhibition of fixation resulted in nearly 50% reduction in labeled sucrose and alanine in the leaves. Relative amounts of labeled malic acid, aspartic acid, glutamic acid, asparagine, and serine, on the other hand, increased. Translocation of 14C-assimilates from leaves to roots in intact Canada thistle and soybean plants was inhibited if roots were treated with 1 or 10 ppm picloram for 24 h before exposure to 14CO2. Young leaves of plants so treated, especially soybeans, accumulated very little assimilated 14C compared with similar leaves in control plants. Transport of 14C-assimilates in corn plants was not significantly affected by picloram treatment. Our results suggest that the inhibitory effects of picloram on photosynthetic 14CO2-fixation and on translocation of labeled assimilates in sensitive and resistant species are indirect and are a result of disturbances of other physiological processes.
The ecology of Chytridium deltanum and other fungus parasites on Oocystis spp.
Authors: Masters Margaret J.
Published: September 2008

Consideration of the population curves of Oocystis crassa and O. lacustris in Lake Manitoba during the summers of 1966 and 1967, and July 1968, indicated that the aquatic fungus Chytridium deltanum was able in two instances to attack growing populations of these algae. This strongly suggested that the fungus was a parasite. However, in July 1965, in Cadham Bay, the fungus bloomed as the host population stopped growing and began to decline. Probably the host cells were slightly senescent at that time and thus more susceptible to fungus attack. Consideration of the composition of the fungus population showed that during one epidemic at least, large numbers of zoospores were released every 7 to 9 days. This suggested a nearly synchronous development of the fungus population. It was also observed that zoospores, able to encyst and successfully infect one host, were sometimes unable to attack another potential host present at the same time. In 1966 and 1967 the fungus appeared a few days after the water had reached 25C. Comparison of culture data for the algae and field studies indicated that Chytridium deltanum most commonly grew on the algae at temperatures above the optimum for the algae.
Cytotaxonomic studies of the closely allied Draba cana, D. cinerea, and D. groenlandica in Canada and Alaska
Authors: Mulligan Gerald A.
Published: September 2008

The cytotaxonomy of three closely related species of Draba is discussed and a key is given: D. cana Rydberg (2n = 32), D. cinerea Adams (2n = 48 and 64), and D. groenlandica E. Ekman (2n = 64). Evidence is presented to show that the name D. lanceolata Royle has been misapplied to plants that should be called D. cana.Scanning electron microscope examinations were made of hairs on leaves and silicles and the value of the different types of hairs as morphological characters in the taxonomy of Draba species is stressed.
A method for extraction of extracellular fluid: use in development of a physiological saline for Venus's-flytrap
Authors: Jacobson Stuart L.
Published: September 2008

Extracellular fluid was extracted by centrifugation from the tissue of the traps of the plant Venus's-flytrap. The extracted fluid was subjected to an extensive physicochemical analysis and the results were compared to a similar analysis of exudation sap. The results of the analysis of the extracted fluid served as a basis for the formulation of a physiological perfusion fluid which was compatible with the tissue of the flytrap. The methods used in the extraction and analysis of the fluid are described. The efficacy of the extraction method is discussed.
Histological studies on the genus Fucus. V. An autoradiographic and electron microscopic study of the early stages of regeneration
Authors: Fulcher R. Gary , McCully Margaret E.
Published: September 2008

Early stages of regeneration in Fucus vesiculosus L. have been studied using segments of vegetative tissue from mature plants cultured in natural seawater. Changes in the production of sulfated polysaccharide at the wound surfaces of the segments were traced by light microscope autoradiography of applied 35SO4− at various intervals after the plants were wounded. Within 6 h after wounding, newly synthesized sulfated polysaccharide is deposited at the extensively pitted cross walls which separate wounded and unwounded filament cells. As regeneration continues, this deposition is no longer confined to the cross walls but occurs throughout the extracellular matrix adjacent to the wound surface.Thin sections of regenerating segments were prepared for electron microscopy at intervals of up to 30 days of culture. Within 24 h after wounding, a layer of microfibrils probably composed of alginic acid is deposited asymmetrically within the existing cell walls of filament cells adjacent to wounded cells. About 2 weeks after wounding, the ends of filament cells adjacent to the wound surface expand laterally in the regions of cells where the newly deposited wall penetrates the original wall. Subsequent division and growth of these cells produces a ‘plate’ of cells at the wound surface which differentiates into new epidermis and cortex.
Translocation of 14C in ponderosa pine seedlings
Authors: Ziemer Robert R.
Published: September 2008

The movement of 14C from the old needles to the roots, and later to the new needles, was measured in 2-year-old ponderosa pine seedlings. The seedlings were in one of three growth stages at the time of the feeding of 14CO2: 9 days before spring bud break with no root activity; 7 days before spring bud break with high root activity; and 7 days after spring bud break with moderate root activity. The form of the curves of count rate plotted against time are similar for a given plant part. Immediately after being fed 14CO2, year-old needles had high 14C count rates which dropped rapidly, leveled out within 7 to 10 days, and reached a steady state residual count rate after 10 to 20 days. The decrease in count rate from the old needles was followed by an increase in count rate by the root tip and (or) the new needles. The count rate of the root tips increased from background to a peak within 3 to 7 days, then decreased for the duration of the study. The details and timing of movement of 14C to and from plant parts was a function of the growth state at the time of 14CO2 feeding.
Loss of photosystem II during ontogeny of sorghum bundle sheath chloroplasts
Authors: Downton W. J. S. , Pyliotis N. A.
Published: September 2008

The bundle sheath chloroplasts of Sorghum bicolor lose their grana during ontogeny. Their ability to reduce the Hill reagent tetranitro blue tetrazolium chloride is also lost. Grana appear necessary for non-cyclic photosynthetic electron flow.
Verticillium wilt of chrysanthemum: colonization of leaves in relation to symptom development
Authors: Hall R. , Busch L. V.
Published: September 2008

The vascular system of leaves of chrysanthemum plants inoculated with Verticillium dahliae was invaded by mycelium before the appearance of visible wilt symptoms. After flower buds appeared a rapid rise in the number of propagules of fungus in the leaf was followed by a rise in severity of visible wilt symptom expression and conductivity of leaf exudate. Those portions of the leaf with the most advanced stages of wilt contained the greatest amounts of fungus. It is suggested that the mycelium within the leaf makes a significant contribution to the development of symptoms of wilt.
Two races of Cladosporium fulvum new to Ontario and further studies of Cf1 resistance in tomato cultivars
Authors: Patrick Z. A. , Kerr E. A. , Bailey D. L.
Published: September 2008

Two races of Cladosporium fulvum, hitherto not encountered from the Niagara Peninsula or adjacent areas of Ontario, Canada, are reported as races 11 and 12. They are described in terms of their infection capabilities on differential tomato hosts carrying the Cf1, Cf2, Cf3, or Cf4 resistance genes. A tabular summary compares the infection capabilities of races 11 and 12 with those of four other presently available C. fulvum races on the differential hosts used for their characterization. Of the four resistance genes which have been incorporated in the various tomato cultivars only Cf1 and Cf4 appear to condition resistance to race 11 and only Cf1 to race 12. Results of inoculation studies with C. fulvum under controlled conditions of light, temperature, and relative humidity are discussed. Comparative studies of their reaction to races 1 and 12 indicate that certain tomato cultivars reported to carry the Stirling Castle, or Cf1, resistance no longer possess it and that additional resistance genes may be present in others.
Studies on marine algae of Newfoundland. II. On the occurrence of Tilopteris mertensii
Authors: South G. R. , Hill R. D.
Published: September 2008

Tilopteris mertensii (Turn. in Sm.) Kütz. (order Tilopteridales, family Tilopteridaceae) is reported for the first time from Newfoundland. The record represents the third known locality for the species in North America. Newfoundland plants bore uninucleate monospores and plurilocular sporangia. Preliminary observations indicate that reproduction in Newfoundland is asexual, by direct germination of the monospores, with no apparent function of the motile spores.
Interaction between clover phyllody and celery-infecting aster yellows causal agents in plants
Authors: Chiykowski L. N.
Published: September 2008

Interaction tests, using aster (Callistephus chinensis Nees) as the host plant and Macrosteles fascifrons (Stål) as the vector, showed that infection with clover phyllody causal agent (CPCA) did not protect the plant against subsequent infection with a celery-infecting strain of aster yellows causal agent (AYCA), although symptom development was delayed. However, infection with AYCA prevented subsequent infection with CPCA. These interactions indicate that CPCA and AYCA are related. Both causal agents could be recovered from some dually infected plants.
On the identification of native auxins in citrus tissues
Authors: Goldschmidt E. E. , Monselise S. P. , Goren R.
Published: September 2008

Attempts were made to characterize the native auxins of citrus tissues. Paper chromatography with eight solvent systems and copartition followed by cochromatography with IAA-2-14C suggest that the auxin of citrus shoots is identical with IAA. This evidence is discussed and compared with other studies of auxin identification reported in the literature.
A chromatographic and cytological study of Dryopteris dilatata in North America and eastern Asia
Authors: Widén Carl-Johan , Britton Donald M.
Published: September 2008

A chromatographic analysis of the phloroglucinol derivatives of 123 collections of Dryopteris intermedia Gray (2x), D. assimilis S. Walker (2x) from western North America, D. "dilatata" from eastern North America (2x), D. "austriaca" from Japan and Kamchatka, "Aspidium dilatatum" from Siberia, D. campyloptera Clarkson (4x) from eastern North America, D. spinulosa Watt (4x) from North America, the hybrids D. "dilatata" × campyloptera (3x) and D. intermedia × spinulosa (3x) is presented. D. "dilatata" from eastern North America has an extremely variable phloroglucinol content, which limits the utility of the analysis for taxonomy. The chromatographic and cytological results are discussed in connection with the evolution of the two tetraploid taxa, D. campyloptera and D. spinulosa. The intra-specific variability of each taxon is discussed and compared with the extensive European studies. The material investigated may be considered to belong to the following species: D. intermedia Gray (2x), D. assimilis S. Walker (2x), D. campyloptera Clarkson (4x), and D. spinulosa Watt (4x). Only two different ancestral genomes are considered to be present in these four species, one in the first three species, and two in D. spinulosa.
The catabolic fission of the aromatic ring of phenylalanine by marine planktonic algae
Authors: Vose J. R. , Cheng J. Y. , Antia N. J. , Towers G. H. N.
Published: September 2008

Twenty-two unicellular marine species belonging to seven algal divisions were tested for their ability to cleave the aromatic ring of phenylalanine. Nine species showed production of 14CO2 after incubation with 14C-ring labeled DL-phenylalanine. This catabolic activity was randomly distributed among the algal classes, although it appeared to be particularly common in pennate diatoms and absent in centric diatoms.
Respiration of developing castorbean seeds
Authors: Agrawal P. K. , Canvin D. T.
Published: September 2008

The rate of oil synthesis in the developing castor oil seed increased from 0.02 mg oil.day−1.100 mg−1 (dry weight) at 6 days after fertilization to 3.84 mg.day−1.100 mg−1 30 days after fertilization. Thereafter, it decreased with no oil synthesis occurring in seed 54 days after pollination. The rate of respiration of the seed was generally correlated with the rate of oil synthesis and peak respiratory rates of 71 μl O2 and 125 μl CO2.h−1.100 mg−1 (fresh weight) were observed in seeds 27 days after fertilization. The respiratory quotient increased from 1.2 in seed 12 days after fertilization to 1.7 to 1.9 during the period of most rapid oil synthesis. The C6/C1 ratio was always less than 0.5 and indicated that the pentose phosphate pathway was operative at all stages of castor oil seed development.
Media for growth of flax tissue culture
Authors: Ibrahim R. K.
Published: September 2008

A callus tissue culture from flax cotyledons reached maximum growth on a medium rich in mineral salts and supplemented with 2 mg/l α-naphthalene acetic acid, 0.05 mg/l kinetin, 15% coconut milk, and 3% sucrose. While tissue differentiation was evident and root formation was induced with increasing auxin concentrations, higher kinetin levels or the addition of L-tyrosine failed to promote shoot formation.
Metabolism of glycolic acid-1-14C in barley leaves with or without added CO2
Authors: Tamàs Imre A. , Bidwell R. G. S.
Published: September 2008

Detached primary leaves of barley (Hordeum vulgare L. var. Dayton) were supplied with glycolate-1 -14C in light or darkness with or without CO2, and the radioactivity of soluble metabolites and evolved CO2 was measured at intervals. The results of these experiments suggest that exogenously supplied glycolate is metabolized by two distinct pathways in illuminated leaves. It may be converted to sucrose outside the chloroplasts, presumably via the glycolate pathway. Alternatively glycolate carbon, through some product of its metabolism, enters the chloroplasts and becomes incorporated into intermediates of the Calvin cycle, from which photorespired CO2 is derived. Endogenous glycolate, originating from Calvin cycle intermediates, may leave the chloroplasts and become a substrate for sucrose synthesis. Exchange of carbon therefore appears to take place between the Calvin cycle inside and the glycolate pathway outside the chloroplasts. This exchange gives a net flow of carbon out of the chloroplasts during photosynthetic CO2 fixation. However, at low external CO2 concentration the flow of carbon from the glycolate pathway into the Calvin cycle in chloroplasts is greatly enhanced, providing substrate for CO2 production. Exogenous glycolate apparently does not directly enter the site of CO2 production in light. However, it is converted to CO2 in darkness, without the participation of the Calvin cycle.
Transfer of 35S from wheat to the powdery mildew fungus with compatible and incompatible parasite/host genotypes
Authors: Slesinski R. S. , Ellingboe A. H.
Published: September 2008

Development of Erysiphe graminis f.sp. tritici on wheat, Triticum aestivum, was studied with compatible and incompatible parasite/host genotypes by measuring the rates of transfer of a radioactive tracer from host to parasite during primary infection. Inoculated wheat plants were fed 35SO4− for various 5-h periods beginning 1 to 21 h after inoculation. Rates of 35S transfer were determined by removing the portion of the fungus on the surface of the leaf with a parlodion film and measuring the amount of radioactivity transferred to the parasite during each 5-h period. Four different parasite/host genotypes which specify incompatibility of the relationship, i.e. P1/Pm1, P2/Pm2, P3a/pm3a, and P4/pm4, differed in the inhibition of 35S transfer according to the time and extent of the incompatible interaction specified by each genotype. With the four genotypes P1/Pm1, P1/pm1, p1/pm1, and p1/Pm1 representing alternative combinations of corresponding genes in the parasite and the host, low rates of transfer were observed with the P1/Pm1 incompatible genotype while similar high rates of transfer were observed with each of the remaining compatible genotypes except p1/Pm1. Rates of 35S transfer were lower for the p1/Pm1 genotype than observed with p1/pm1 even though all three genotypes specify compatibility between parasite and host as evaluated by morphological development of the parasite during primary infection and by infection type at 7 days after inoculation.
The presence and role of phosphopyruvate carboxylase in etiolated coleoptiles of Avena sativa
Authors: Bown A. W. , Lampman W. W.
Published: September 2008

Phosphopyruvate carboxylase and malic enzyme were detected in etiolated coleoptiles of Avena sativa, and it was concluded that the incorporation of 14C-labeled bicarbonate into aspartate and glutamate involved the activity of the former enzyme. IAA stimulated the fixation of labeled bicarbonate, and the incorporation of labeled leucine into protein was increased in the presence of carbon dioxide. It is suggested that the carbon dioxide stimulated growth of Avena coleoptiles is due to an increased rate of protein synthesis which is dependent on carbon dioxide fixation.
Plantlet formation from flowers of Trifolium repens
Authors: Vasil Vimla , West Sherlie H.
Published: September 2008

In Trifolium repens L., plantlets arose from the axil of the five petals when the flower was still in the bud. These plantlets were produced on virus-free plants which had been grown under controlled environmental regimes and appeared similar to the plantlets produced when plants were virus infected.
Resistant response of lodgepole pine to inoculation with Europhium clavigerum in different months and at different heights on stem
Authors: Reid R. W. , Shrimpton D. M.
Published: September 2008

Lodgepole pines were inoculated in groups of 100 trees with Europhium clavigerum at monthly intervals between May and October. The number of trees showing a fully resistant response to this inoculation reached a maximum in early July and then gradually declined. When resistant lodgepole pine trees were inoculated at intervals of 6 ft up the stem, the extent of the resistant response was at a maximum in the lower 20 ft of the stem.Des Pins de Murray furent, par groupes de 100, inoculés d'Europhium clavigerum chaque mois entre mai et octobre. Le nombre d'arbres présentant une résistance absolue à cette inoculation atteignit un maximum au début de juillet, puis décrut progressivement.La réaction de résistance était maximale dans les 20 pieds de base chez les sujets résistants inoculés à tous les 6 pieds le long de leurs tiges.
Occurrence and distribution of zoosporic fungi from Devon Island, Canadian Eastern Arctic
Authors: Booth Tom , Barrett Paul
Published: September 2008

Zoosporic fungi, mainly Chytridiales, are recorded from 61 sites in 10 different Base Camp Lowland habitats. Of the eight genera and 19 species recovered Catenophlyctis (Phlyctorhiza) variabilis, Hyphochytrium catenoides, Nowakowskiella elegans, Olpidium pendulum, Rhizophydium pollinis-pini, R. sphaerotheca, Rhizophydium sp. (utricularae?), and Pythium irregularae have been reported from the Arctic before. Chytriomyces annulatus, C. poculatus, Nowakowskiella macrospora, N. ramosa, Rhizidium verrucosum, Rhizophydium angulosum, R. coronum, R. eleyensis, R. karlingii, Rhizophydium sp. (nodulosum?), and Rhizophydium sp. (patellarium?) are reported for the first time from the Arctic.
Phleospora idahoensis on native Festuca spp. in the northwestern Great Plains
Authors: Smith J. Drew
Published: September 2008

Cultural characters, spore morphology, and size indicated that a fungus consistently associated with culm and inflorescence lesions on the native fescues Festuca scabrella Torr., F. idahoensis Elmer, and F. ovina L. in Western Canada and northwestern United States was Phleospora idahoensis Sprague. The fungus was morphologically and culturally identical with P. idahoensis, which recently caused severe out-breaks of a stem eyespot disease in crops of the introduced creeping red fescue, F. rubra L. subsp. rubra, in northern Alberta and on the ‘Olds’ cultivar in central Alberta. The widespread occurrence of P. idahoensis in Western Canada and northwestern Great Plains suggests that it is endemic. The epidemiological implications for crops of introduced fescues of the occurrence of the pathogen on native species are considered.
Taxonomy of Trifolium (Leguminosae). III. T. eriocephalum
Authors: Gillett John M.
Published: September 2008

The taxonomy of the Trifolium eriocephalum Nutt. complex is reviewed. Trifolium arcuatum Piper and its variety cusickii Piper are transferred to the subspecific level, and two new subspecies, cascadense and martinii are described. The name arcuatum is restored over piperi employed by Martin. The species, in the broad sense, has been found to be consistently diploid, n = 8. The distribution of individual morphological characters frequently cuts across subspecific lines indicating closeness of relationship. Keys to subspecies, synonymy, distributional records and maps, and chromosome numbers are presented.
Vitamin requirements of the fungal endophytes of Arundina chinensis
Authors: Stephen R. C. , Fung K. K.
Published: September 2008

The vitamin requirements of two Rhizoctonia fungus endophytes of the orchid Arundina chinensis are reported. Addition of a mixture of nine vitamins to a basal medium supplemented by five amino acids increased the growth of one isolate (R29) but not the other (R14). The inclusion of proline and methionine in the medium inhibited the response of R14 to the vitamins present. Both isolates were partially deficient in, if not completely heterotrophic for, thiamin and p-aminobenzoic acid, and R14 required added biotin for optimum growth under the conditions of the experiment.
The annual occurrence and effects of semimature-tissue needle blight on white pine
Authors: Linzon S. N.
Published: September 2008

The occurrence of semimature-tissue needle blight (SNB) on eastern white pine (pinus strobus L.) was closely followed for 7 years, 1957 to 1963. White pines susceptible to SNB displayed recurrent foliar symptoms in some years. Annual fluctuations in the incidence of SNB occurred in a similar pattern on widely separated sample plots in a localized area. Major outbreaks of SNB were infrequent and were often found to occur during a continuous sunny period following a period of excess rainfall. The adverse effects of the disease on foliage were reflected in reduced growth in other parts of affected trees and in premature death of perennially blighted trees.
The effect of imbibition and vernalization on the uptake and distribution of 32P-orthophosphate in the grains and grain parts of a spring and winter wheat
Authors: Jones R. A. D. , Kates M. , Weinberger Pearl
Published: September 2008

32P-orthophosphate was taken up by both Marquis and Rideau wheat grains during imbibition at 24 °C and converted mainly into water-soluble organic phosphates and to a much smaller extent into the nucleic acid, phospholipid, and phosphoprotein components of both the whole grains and grain parts. Whereas the 32P incorporation into the nucleic acids and phospholipids of Rideau grains increased during the chilling period (0–5 weeks), the incorporation of 32P into these fractions was relatively low in Marquis grains and only slightly affected by cold treatment. The results suggest that the cold treatment results in overall stimulation of turnover or synthesis of nucleic acids, phosphoproteins, and membrane phospholipids in Rideau grains. The 32P incorporation data also indicate that the scutellum of both varieties acts as a "sink" for the phosphate metabolites from the other grain parts.
Chytridium deltanum n. sp. and other Phycomycetes on Oocystis spp. in the Delta Marsh, Manitoba
Authors: Masters Margaret J.
Published: September 2008

A new Chytridium species, C. deltanum, is described growing on Oocystis crassa, O. lacustris, O. submarina, and O. parva. A sexual process is involved in the formation of the endobiotic resting spores. The occurrence of Chytridium oocystidis Huber-Pestalozzi on O. lacustris and O. crassa is briefly described. Three other fungi as yet not completely identified, but evidently new to science, are described on Oocystis spp. One of these appears to be a Lagenidium species.
Polygalacturonate trans-eliminase and cellulase production by virulent and avirulent isolates of Sclerotium bataticola in culture and in sunflowers
Authors: Chan Yu-Ho , Sackston W. E.
Published: September 2008

Polygalacturonate trans-eliminase (PGTE) activity was found in dialyzed filtrates from cultures of three virulent (M, N, D) and one moderately virulent (G) isolates of Sclerotium bataticola, but not from two avirulent isolates (E and R). Activity of PGTE, presumably exo-PGTE, was found in dialyzed extracts from sunflower plants 42 h after unwounded stem base inoculation (USBI) with the two most virulent isolates (M and N). None was found in extracts from plants inoculated by the toothpick method (TPI). Cellulase activity was present in dialyzed filtrates from cultures of all six isolates. Dialyzed extracts from plants showed cellulase activity 42 h after USBI with isolates N, M, and D, but not G, E, and R. Extracts from plants in the TPI series showed cellulase activity 18 h and higher activity 36 h after inoculation with isolates N, D, and G, but not M, E, and R. No pectin trans-eliminase activity was found either in culture filtrates or in extracts from inoculated sunflower stems. None of the enzymes was detected in extracts from uninoculated stems.