bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling of CO2-Hydrate Formation in Geological Reservoirs by Injection of CO2 Gas
Authors: Uddin M. , Coombe D. , Wright F.
Published: August 2008

Continuing concern about the impacts of atmospheric carbon dioxide (CO2) on the global climate system provides an impetus for the development of methods for long-term disposal of CO2 produced by industrial and other activities. Investigations of the CO2-hydrate properties indicate the feasibility of geologic sequestration CO2 as gas hydrate and the possibility of coincident CO2 sequestration/CH4 production from natural gas hydrate reservoirs. Numerical studies can provide an integrated understanding of the process mechanisms in predicting the potential and economic viability of CO2 gas sequestration, especially when utilizing realistic geological reservoir characteristics in the models. This study numerically investigates possible sequestration of CO2 as a stable gas hydrate in various reservoir geological formations. As such, this paper extends the applicability of a previously developed model to more realistic and relevant reservoir scenarios. A unified gas hydrate model coupled with a thermal reservoir simulator (CMG STARS) was applied to simulate CO2-hydrate formation in four reservoir geological formations. These reservoirs can be described as follows. The first reservoir (Reservoir I) is similar to tight gas reservoir with mean porosity 0.25 and mean absolute permeability 10mD. The second reservoir (Reservoir II) is similar to a conventional sandstone reservoir with mean porosity 0.25 and mean permeability 20mD. The third reservoir (Reservoir III) is similar to hydrate-free Mallik silt with mean porosity 0.30 and mean permeability 100mD. The fourth reservoir (Reservoir IV) is similar to hydrate-free Mallik sand with mean porosity 0.35 and mean permeability 1000mD. The Mallik gas hydrate bearing formation itself can be described as several layers of variable thickness with permeability variations from 1mDto1000mD, and is addressed as a separate part of this study. This paper describes numerical methodology, model input data selection, and reservoir simulation results, including an enhancement to model the effects of ice formation and decay. The numerical investigation shows that the gas hydrate model effectively captures the spatial and temporal dynamics of CO2-hydrate formation in geological reservoirs by injection of CO2 gas. Practical limitations to CO2-hydrate formation by gas injection are identified and potential improvements to the process are suggested.
An Explicit Analytic Solution of Steady Three-Dimensional Stagnation Point Flow of Second Grade Fluid Toward a Heated Plate
Authors: Mehmood Ahmer , Ali Asif
Published: August 2008

We present a purely analytic solution to the steady three-dimensional viscous stagnation point flow of second grade fluid over a heated flat plate moving with some constant speed. The analytic solution is obtained by a newly developed analytic technique, namely, homotopy analysis method. By giving a comparison with the existing results, it is shown that the obtained analytic solutions are highly accurate and are in good agreement with the results already present in literature. Also, the present analytic solution is uniformly valid for all values of the dimensionless second grade parameter α. The effects of α and the Prandtl number Pr on velocity and temperature profiles are discussed through graphs.
Stochastic Morphological Modeling of Random Multiphase Materials
Authors: Graham-Brady Lori , Xu X. Frank
Published: August 2008

A short-range-correlation (SRC) model is introduced in the framework of Markov/Gibbs random field theory to characterize and simulate random media. The Metropolis spin-flip algorithm is applied to build a robust simulator for multiphase random materials. Through development of the SRC model, several crucial conceptual ambiguities are clarified, and higher-order statistical simulation of random materials becomes computationally feasible. In the numerical examples, second- and third-order statistical simulations are demonstrated for biphase random materials, which shed light on the relationship between nth-order correlation functions and morphological features. Based on the observations, further conjectures are made concerning some fundamental morphological questions, particularly for future investigation of physical behavior of random media. It is expected that the SRC model can also be extended to third- and higher-order simulations of non-Gaussian stochastic processes such as wind pressure, ocean waves, and earthquake accelerations, which is an important research direction for high fidelity simulation of physical processes.
Modeling Helicopter Blade Sailing: Dynamic Formulation and Validation
Authors: Wall A. S. , Afagh F. F. , Langlois R. G. , Zan S. J.
Published: August 2008

Rotor blade sailing, which is characterized by excessive deflection of rotor blades, can be experienced by shipboard helicopters during rotor start-up and shut-down. In an attempt to model the complete ship-helicopter-rotor system in a way that is geometrically representative and computationally efficient, the system was represented as a discrete-property rigid-body and flexible-element system capable of simulating many important dynamic effects that contribute to the motion of rotor blades. This paper describes the model in detail and discusses validation cases. While both dynamic effects and aerodynamic effects are believed to be important components of blade sailing, this paper focuses exclusively on the dynamics. The validation cases discussed herein suggest that the modeling approach presented offers excellent potential for efficiently modeling blade sailing and other blade motion phenomena.
Constructing
Multilayer Feedforward Neural Networks to Approximate Nonlinear Functions in Engineering Mechanics
Applications
Authors: Pei Jin-Song , Mai Eric
C.
Published: August 2008

This paper presents a major step in the development and validation of a systematic prototype-based methodology for designing multilayer feedforward neural networks to model nonlinearities common in engineering mechanics. The applications of this work include (but are not limited to) system identification of nonlinear dynamic systems and neural-network-based damage detection. In this and previous studies (Pei, J. S., 2001, “Parametric and Nonparametric Identification of Nonlinear Systems,” Ph.D. thesis, Columbia University; Pei, J. S., and Smyth, A. W., 2006, “A New Approach to Design Multilayer Feedforward Neural Network Architecture in Modeling Nonlinear Restoring Forces. Part I: Formulation,” J. Eng. Mech., 132(12), pp. 1290–1300; Pei, J. S., and Smyth, A. W., 2006, “A New Approach to Design Multilayer Feedforward Neural Network Architecture in Modeling Nonlinear Restoring Forces. Part II: Applications,” J. Eng. Mech., 132(12), pp. 1301–1312; Pei, J. S., Wright, J. P., and Smyth, A. W., 2005, “Mapping Polynomial Fitting Into Feedforward Neural Networks for Modeling Nonlinear Dynamic Systems and Beyond,” Comput. Methods Appl. Mech. Eng., 194(42–44), pp. 4481–4505), the authors do not presume to provide a universal method to approximate any arbitrary function. Rather the focus is given to the development of a procedure which will consistently lead to successful approximations of nonlinear functions within the specified field. This is done by examining the dominant features of the function to be approximated and exploiting the strength of the sigmoidal basis function. As a result, a greater efficiency and understanding of both neural network architecture (e.g., the number of hidden nodes) as well as weight and bias values is achieved. Through the use of illuminating mathematical insights and a large number of training examples, this study demonstrates the simplicity, power, and versatility of the proposed prototype-based initialization methodology. A clear procedure for initializing neural networks to model various nonlinear functions commonly seen in engineering mechanics is provided. The proposed methodology is compared with the widely used Nguyen–Widrow initialization to demonstrate its robustness and efficiency in the specified applications. Future work is also identified.
A Finite-Deformation Shell Theory for Carbon Nanotubes Based on the Interatomic Potential—Part I: Basic Theory
Authors: Wu J. , Hwang K. C. , Huang Y. , Song J.
Published: August 2008

A finite-deformation shell theory for carbon nanotubes (CNTs) is established directly from the interatomic potential for carbon to account for the effect of bending and curvature. Its constitutive relation accounts for the nonlinear multibody atomistic interactions and therefore can model the important effect of CNT chirality and radius. The equilibrium equations and boundary conditions are obtained for the symmetric stresses and bending moments, which are different from many existing shell theories that involve asymmetric stress and bending moments. The theory is used in Part II of this paper to study the instability of carbon nanotubes subjected to different loadings.
Impact of Viscoplastic Bodies: Dissipation and Restitution
Authors: Ismail K. A. , Stronge W. J.
Published: August 2008

A viscoplastic coefficient of restitution (COR) that accounts for nonfrictional sources of energy dissipation is determined for direct collision between hard compliant bodies. This COR incorporates effects of both irreversible elastic-plastic material (rate-independent) and viscoelastic (rate-dependent) behaviors. The COR is calculated based on a modified Maxwell model for compliance of the bodies in the small deforming region around the initial contact point. Modifications to the Maxwell model incorporate the effects of plasticity and viscoelasticity, so the calculated COR gives a value that considers both hysteresis due to the plastic deformation and viscoelastic (rate-dependent) sources of energy dissipation during collision.
Dynamics of Mechanical Systems and the Generalized Free-Body Diagram—Part II: Imposition of Constraints
Authors: Kövecses József
Published: August 2008

In this part of the work we present some applications of the formulation developed in Part I (Kövecses, 2008, “Dynamics of Mechanical Systems and the Generalized Free-Body Diagram—Part I: General Formulation,” ASME J. Appl. Mech., 75(6), p. 061012) for the generalized free-body diagram in configuration space. This involves the specification and imposition of constraint conditions, which were identified as Step 2 of the analysis of a mechanical system in Part I. We will particularly consider bilaterally and unilaterally constrained systems, where constraints are realized via ideal or nonideal interfaces. We also look at the general case where the constraint configuration is possibly redundant. The results represent novel forms of dynamics models for mechanical systems, and can offer the possibility to gain more insight for simulation, design, and control.
Mechanics of Microtubule Buckling Supported by Cytoplasm
Authors: Jiang Hanqing , Zhang Jiaping
Published: August 2008

The cytoskeleton provides the mechanical scaffold and maintains the integrity of cells. It is usually believed that one type of cytoskeleton biopolymer, microtubules, bears compressive force. In vitro experiments found that isolated microtubules may form an Euler buckling pattern with a long-wavelength for very small compressive force. This, however, does not agree with in vivo experiments where microtubules buckle with a short-wavelength. In order to understand the structural role of microtubules in vivo, we developed mechanics models that study microtubule buckling supported by cytoplasm. The microtubule is modeled as a linearly elastic cylindrical tube while the cytoplasm is characterized by different types of materials, namely, viscous, elastic, or viscoelastic. The dynamic evolution equations, the fastest growth rate, the critical wavelength, and compressive force, as well as equilibrium buckling configurations are obtained. The ability for a cell to sustain compressive force does not solely rely on microtubules but is also supported by the elasticity of cytoplasm. With the support of the cytoplasm, an individual microtubule can sustain a compressive force on the order of 100pN. The relatively stiff microtubules and compliant cytoplasm are combined to provide a scaffold for compressive force.
A Materials Selection Protocol for Lightweight Actively Cooled Panels
Authors: Valdevit Lorenzo , Vermaak Natasha , Zok Frank W. , Evans Anthony G.
Published: August 2008

This article provides a materials selection methodology applicable to lightweight actively cooled panels, particularly suitable for the most demanding aerospace applications. The key ingredient is the development of a code that can be used to establish the capabilities and deficiencies of existing panel designs and direct the development of advanced materials. The code is illustrated for a fuel-cooled combustor liner of a hypersonic vehicle, optimized for minimum weight subject to four primary design constraints (on stress, temperatures, and pressure drop). Failure maps are presented for a number of candidate high-temperature metallic alloys and ceramic composites, allowing direct comparison of their thermostructural performance. Results for a Mach 7 vehicle under steady-state flight conditions and stoichiometric fuel combustion reveal that, while C–SiC satisfies the design requirements at minimum weight, the Nb alloy Cb752 and the Ni alloy Inconel X-750 are also viable candidates, albeit at about twice the weight. Under the most severe heat loads (arising from heat spikes in the combustor), only Cb752 remains viable. This result, combined with robustness benefits and fabrication facility, emphasizes the potential of this alloy for scramjets.
Reliability of Strongly Nonlinear Single Degree of Freedom Dynamic Systems by the Path Integration Method
Authors: Iourtchenko Daniil , Mo Eirik , Naess Arvid
Published: August 2008

This paper presents a first passage type reliability analysis of strongly nonlinear stochastic single-degree-of-freedom systems. Specifically, the systems considered are a dry friction system, a stiffness controlled system, an inertia controlled system, and a swing. These systems appear as a result of implementation of the quasioptimal bounded in magnitude control law. The path integration method is used to obtain the reliability function and the first passage time.
Numerical Analysis of Double Contacts of Similar Elastic Materials
Authors: Sundaram N. , Farris T. N.
Published: August 2008

A fast numerical method based on the Cauchy singular integral equations is presented to determine the contact pressure and extents for the contact of two-dimensional similar isotropic bodies when the contact area consists of two separate regions. The partial-slip problem is then solved to determine shear tractions using an equivalence principle. The extents of the contact are not all independent but related to a compatibility equation constraining the displacements of an elastic body in contact with an equivalent rigid body. A similar equation is found for the extents of the stick zones in partial-slip problems. The effects of load history are incorporated into the shear solution. The method is applicable to a wide range of profiles and it provides significant gains in computational efficiency over the finite element method (FEM) for both the pressure and partial-slip problems. The numerical results obtained are compared with that from the FEM for a biquadratic indenter with a single concavity and showed good agreement. Lastly, the transition behavior from double to single contacts in biquadratic profiles is investigated.
Chemokine Signaling Controls Endodermal Migration During Zebrafish Gastrulation
Authors: Nair Sreelaja , Schilling Thomas F.
Published: August 2008

Directed cell movements during gastrulation establish the germ layers of the vertebrate embryo and coordinate their contributions to different tissues and organs. Anterior migration of the mesoderm and endoderm has largely been interpreted to result from epiboly and convergent-extension movements that drive body elongation. We show that the chemokine Cxcl12b and its receptor Cxcr4a restrict anterior migration of the endoderm during zebrafish gastrulation, thereby coordinating its movements with those of the mesoderm. Depletion of either gene product causes disruption of integrin-dependent cell adhesion, resulting in separation of the endoderm from the mesoderm; the endoderm then migrates farther anteriorly than it normally would, resulting in bilateral duplication of endodermal organs. This process may have relevance to human gastrointestinal bifurcations and other organ defects.
A 12-month prospective cohort study of injury in international rowers
Authors: Wilson F , Gissane C , Gormley J , Simms C
Published: August 2008

Objective

In this study, the injury incidence and association with type and volume of training in international rowers were described.

Design

A prospective cohort design was used over a 12-month period.

Patients

20 international rowers who were competing as part of the Irish Amateur Rowing Union squad system.

Methods

The rowers were interviewed monthly, and data were collected regarding their training and competition exposure as well as their injury experience.

Results

A mean injury rate of 3.67 per 1000 exposure hours was reported with a total of 44 injuries reported in a 12-month period. The mean number of injuries sustained per athlete was 2.2 (1.24) over the 12-month period. The area where the greatest number of injuries were reported was the lumbar spine (31.82% of total injuries, 95% CI 20 to 50) (fig 2) followed by the knee (15.91% of total injuries, 95% CI 10 to 30) and the cervical spine (11.36% of total injuries, 95% CI 5 to 24). Half of the injuries (22 injuries, 50% of total reported injuries) were to the spine (χ2= 30.8, df = 9, p = 0.0003). Ergometer training load was the most significantly associated with injury risk (r = 0.68, p = 0.01).

Conclusion

International rowers are at higher risk of injury than most non-contact sports and some contact sports. The high risk of lumbar spine injury and the significant association of high volume of ergometer training merit further research to reduce time and competition lost to injury.
Antibiotic treatment in patients with low-back pain associated with Modic changes Type 1 (bone oedema): a pilot study
Authors: Albert H B , Manniche C , Sorensen J S , Deleuran B W
Published: August 2008

Objective:

The aim of this study was to assess the clinical effect of antibiotic treatment in a cohort of patients with low-back pain (LBP) and Modic changes Type 1 (bone oedema) following a lumbar herniated disc.

Design:

This was a prospective uncontrolled trial of 32 LBP patients who had Modic changes and were treated withAmoxicillin-clavulanate(500 mg/125 mg) 3 × day for 90 days. All patients had previously participated in a randomised controlled trial (RCT) that investigated active conservative treatment for a lumbar herniated disc (n = 166). All patients in that RCT who had Modic changes and LBP at 14 months follow-up (n = 37) were invited to participate in this subsequent antibiotic trial but five did not meet the inclusion criteria.

Results:

29 patients completed the treatment, as three patients dropped out due to severe diarrhoea. At the end of treatment and at long-term follow-up (mean 10.8 months) there was both clinically important and statistically significant (p⩽0.001) improvement in all outcome measures: LBP intensity, number of days with pain, disease-specific and patient-specific function, and global perceived effect.

Conclusions:

In this uncontrolled trial, the clinical effect of antibiotic treatment was large in a group of patients with Modic changes suffering from persistent LBP following a disc herniation. These results provide tentative support for a hypothesis that bacterial infection may play a role in LBP with Modic changes and indicate the need for randomised controlled trials to test this hypothesis.
Extracorporeal shockwave therapy for patellar tendinopathy: a review of the literature
Authors: van Leeuwen M T , Zwerver J , van den Akker-Scheek I
Published: August 2008

Background and purpose:

Extracorporeal shockwave therapy (EWST) has become a popular treatment for patellar tendinopathy. The purpose of this review was to study the effectiveness of ESWT treatment for patellar tendinopathy; to draft guidelines for an effective treatment protocol of ESWT treatment; and to identify topics for further research.

Methods:

A computerised search of the Medline and Embase databases was conducted on 1 August 2007, to identify studies dealing with the effectiveness of ESWT for patellar tendinopathy.

Results:

Seven articles describing the effectiveness of ESWT on patellar tendinopathy, all published after 2000, were included. These studies included a total of 283 patients (298 tendons), 204 of whom (215 tendons) were assigned to ESWT treatment. The treatment results were positive but most studies had methodological deficiencies, small numbers and/or short follow-up periods. Method of application and shockwave generation, energy level, number and frequency of treatments, use of (local) anaesthesia and method of localisation were variable.

Conclusion:

ESWT seems to be a safe and promising treatment for patellar tendinopathy with a positive effect on pain and function. Based on current knowledge it is impossible to recommend a specific treatment protocol. Further basic and clinical research into the working mechanism and effectiveness of ESWT for patellar tendinopathy are necessary.
THE USE OF A PERCOLATION TECHNIQUE IN STUDYING ANTIBIOTIC PRODUCTION IN SOIL
Authors: Stevenson I. L. , Lochhead A. G.
Published: August 2008

The adaptation of a percolation technique to the study of the production of antibiotics in soil is described. Antibiotic activity is determined by assays of a continuously circulating soil solution without disturbing the soil sample itself. The advantages of this technique over existing methods of study are discussed. Results are presented illustrating the production of antibiotics in sterile soil by a Penicillium sp. and two unidentified Streptomyces spp.
A FURTHER SURVEY OF PLANTS FOR ANTIBACTERIAL SUBSTANCES
Authors: MacDonald R. E. , Bishop C. J.
Published: August 2008

One hundred and seventy-seven Nova Scotian plants were tested for antibacterial activity using S. aureus and E. coli as test organisms. Of the plants tested, 33.3% were active, 32.2% against S. aureus and 5.1% against E. coli. No relationship was found between the activity of the extracts and their pH. The plants tested are listed together with their degree of activity. Among those with the most active extracts were Alnus crispa, Drosera intermedia, Erigeron canadensis, Hypericum spp., and Agrimonia spp.
PRELIMINARY STUDIES OF ROOT AND BASAL STALK ROT OF MATURING CORN IN ONTARIO
Authors: McKeen W. E.
Published: August 2008

In Ontario, basal stalk rot of corn occurs in the autumn and is of major importance, whereas bacterial stalk rot is of no economic significance. The latter disease, which results from stomatal penetration by Erwinia dissolvens, may occur on a few susceptible corn plants in early July during extremely hot humid weather, although ordinarily temperatures are sufficiently low in the province to limit its development. Common basal stalk rot of corn is usually initiated by the spread of organisms from diseased corn roots up into the stalks; rotting may begin also in tunnels produced by corn borers. Diplodia zeae and Gibberella zeae, the two pathogens that are responsible for most of the stalk rotting in the central part of the American corn belt, were of no practical importance during the last two years. Bacteria, Pythium arrhenomanes, and Fusarium moniliforme were commonly found in the necrotic part of the corn stalk. Diseased plants begin to appear in mid-August and daily become more numerous until the first killing frost occurs or the plants become senescent. The leaves suddenly droop and wither, and are dead within four or five days after the first symptoms appear. By this time, the basal part of the stalk is necrotic and at least some of the roots are decayed. Pith tissues are destroyed and the stalk frequently breaks over near the ground level. All stalk rot pathogens finally produce the same syndrome. P. arrhenomanes causes a root necrosis at first which later spreads up into the stalk and, in Ontario, is of major importance in the corn stalk rot disease. Pratylenchus pratensis has been found in corn roots but its importance is unknown.
NUTRITIONAL REQUIREMENTS OF ARTHROBACTER TERREGENS
Authors: Burton Margaret O. , Lochhead A. G.
Published: August 2008

Vitamin and amino acid requirements have been established for Arthrobacter terregens n. sp., an organism found to require an unknown growth factor present in soil extract, liver extract, and culture filtrates of Arthobacter pascens n. sp. Apart from this unknown factor, concentrates of which promote growth at less than 0.1 μgm. per ml., biotin, thiamine, and pantothenic acid were found to be essential. With adequate mineral supplement the nitrogen requirements could be fulfilled by l-glutamic acid, though the latter could be replaced by combinations of other amino acids.
PHYLOGENY OF CAREX IN THE LIGHT OF PARASITISM BY THE SMUT FUNGI
Authors: Savile D. B. O. , Calder J. A.
Published: August 2008

By using evidence derived from the relationships with smut fungi (Cintractia and Planetella) that attack its members, new light has been shed on the phylogeny of Carex. The genus is believed to be essentially monophyletic and derived from Kobresia. It has been found necessary to erect a new subgenus, Kuekenthalia, composed principally of those sections with persistent styles and bladdery perigynia that were formerly placed in Eucarex. Uncinia is shown to be an offshoot of the evolutionary line that gave rise to Kuekenthalia.
ISOLATION OF BACTERIOPHAGES FOR THE DETECTION AND IDENTIFICATION OF SOME SEED-BORNE PATHOGENIC BACTERIA
Authors: Sutton M. D. , Katznelson H.
Published: August 2008

A strain-specific and polyvirulent phage for Pseudomonas pisi Sackett have been isolated from peas. The latter phage lyses also strains of P. glycinea Coerper, P. lachrymans (Smith and Bryan) Carsner, and P. phaseolicola (Burk-holder) Dowson. The polyvirulent phage has been used successfully in detecting the presence of bacterial blight (P. pisi) in pea seed and plant tissue from infected fields. Specific phages for P. atrofaciens (McCullouch) Stevens and P. coronafaciens (Elliott) Stapp have been obtained, respectively, from wheat and oat seeds. Phages specific for Xanthomonas translucens f. sp. hordei, secalis, and hordei-avenae were isolated from barley and oat seed. Attempts to isolate viruses for X. translucens f. sp. cerealis and undulosa were not successful.
FOREST COMMUNITIES IN NORTHWESTERN ALBERTA
Authors: Moss E. H.
Published: August 2008

Spruce, tamarack (larch), balsam fir, pine, and poplar communities of the region are described in terms of floristic composition and ecological relationships. The white spruce (Picea glauca) association is regarded as the climax type of the region. Of four phases or faciations presented by the white spruce association, the feather moss faciation appears to be the climax to which the other faciations tend to develop. Two black spruce (Picea mariana) communities are recognized, the black spruce – feather moss association and the black spruce–peat moss association. Of these, the former is characterized by "feather mosses" such as Hylocomium splendens and has developed on relatively level terrain without much peat formation, whereas the latter has a Sphagnum floor and has arisen in definite depressions through acid bog stages with the production of considerable peat. The black spruce – bog moss community is interpreted as subclimax, with natural succession to the black spruce – feather moss association. The tamarack (Larix laricina) community has many features in common with the black spruce – peat moss association but differs markedly, not only in its dominant species, but because of its development from a Drepano-cladus–Carex–Betula bog under persisting wet conditions. Succession to black spruce commonly occurs. Balsam fir (Abies balsamea) is relatively rare in the region and usually grows in mixed stands with white spruce, paper birch, aspen, and balsam poplar. Two divisions of the pine association are recognized, the jack pine (Pinus banksiana) and the lodgepole pine (P. contorta var. latifolia) consociations. For each of these, two phases are described, the pine – feather moss faciation on the more shaded sites and the pine–heath faciation on the more open and drier areas. Knowledge of the ranges of these two pines in northern Alberta and concerning hybrids between the species is extended. The poplar association, classified as aspen (Populus tremuloides) and balsam poplar (P. balsamifera) consociations, is considered in relation to other vegetation, especially prairie grassland and white spruce. Encroachment of aspen poplar upon native grassland is counteracted by various factors, notably burning. Natural succession of poplar and pine to white spruce is impeded chiefly by forest fires. Some attention is given to phytogeographical problems of this transition region.
STUDIES ON THE ANAEROBIC DISSIMILATION OF GLUCOSE BY BACILLUS SUBTILIS (FORD'S TYPE)
Authors: Neish A. C.
Published: August 2008

Bacillus subtilis (Ford's type) was able to fix only 3% of the NaHC14O3 added during anaerobic dissimilation of glucose, under conditions where Serratia marcescens and Aerobacter aerogenes fixed 38% and 54% respectively. The carbon-14 was found mainly in succinic acid, lactic acid carboxyl, and formic acid, in decreasing order of specific activity. Similar experiments with labelled formate showed it to be relatively inert, most of it being recovered unchanged. Acetate was readily metabolized by B. subtilis during the fermentation of glucose with a marked increase in the amount of 2,3-butanediol and ethanol formed, while the amount of glycerol was decreased to less than one-tenth of the normal value. Experiments with CH3C14OONa proved that the acetate was reduced to ethanol, only traces of acetate carbon being found in 2,3-butanediol or lactic acid. Fermentation of glucose-1-C14 gave 2,3-butanediol and lactic acid labelled in the methyl groups and glycerol labelled mainly in the primary alcohol groups; only a small part of the carbon-14 being found in carbon dioxide.
AIR-BORNE FUNGI IN THE ARCTIC AND OTHER PARTS OF CANADA
Authors: Pady S. M. , Kapica L.
Published: August 2008

Quantitative and qualitative studies were made of the fungi in the air over various parts of Canada and Alaska, continuing studies in arctic aerobiology. In winter, arctic air is apparently sterile: in summer, at Ft. Churchill, Man., ground level samples varied from 0.5 to 4.4 per cu. ft. Cladosporium was the commonest fungus (average 0.5 per cu. ft.), followed by yeasts (0.16), Penicillium (0.06), and Stemphylium (0.03 per cu. ft.). Other fungi present were Pullularia, Botrytis, Aspergillus, Verticillium, Pyrenochaete, Helminthosporium, Phyllosticta, Papularia, Cunninghamella, and Sporormia. Of 3711 colonies 57% failed to sporulate. Silicone slide readings as high as 114.9 fungus spores per cu. ft. were obtained and included the following: yeasts (8.6), Cladosporium (3.8), smuts (2.5), Fusarium (0.6), Alternaria (0.06 per cu. ft.), Venturia, Cercospora, Septoria, rusts, Leptosphaeria, Sordaria, and Pleospora and many hyaline one-celled spores. In two flights to Resolute Bay, N.W.T., the flora was found to be similar to that at Ft. Churchill but numbers did not exceed 1 per cu. ft., although readings up to 78 fungus spores per cu. ft. were recorded on slides in warm air over Hudson Bay. Most of the fungi are considered to be soil types originating in agricultural areas and carried northward by southerly winds. The majority are no longer viable when they reach the arctic. There is evidence that the numbers of fungi are correlated with air masses, not only in the arctic but also in air over other parts of Canada.
MOVEMENT OF RADIOACTIVE ISOTOPES IN YELLOW BIRCH AND WHITE PINE AS DETECTED WITH A PORTABLE SCINTILLATION COUNTER
Authors: Fraser D. A. , Mawson C. A.
Published: August 2008

Movement of rubidium86 and calcium45 injected into the trunks of yellow birch and white pine was followed with a newly-developed portable scintillation counter. Maximum rate of upward movement of the rubidium86 in the xylem of yellow birch approximates one foot per minute along a narrow channel spiralling upward (usually dextrally) from the point where the isotope was first introduced. Movement in decadent yellow birch was very slow with an apparent increase of permeability of the bark tissue as indicated by lateral diffusion of the isotope. In October no upward movement was discerned in healthy trees but rather an active downward translocation in the phloem.
EFFECTS OF EXPOSURE TO DIRECT SUNLIGHT UPON THE DEVELOPMENT OF LEAF STRUCTURE OF TWO DECIDUOUS SHRUB SPECIES
Authors: Cormack R. G. H. , Gorham Anne L.
Published: August 2008

The present anatomical study of sun and shade leaves of two shrub species Menziesia glabella and Lonicera glaucescens is an outgrowth of interest in the response of ground cover plants to increased sunlight as the result of logging operations. Leaves of both shrub species developed on plants fully exposed to the sun are smaller, thicker, more compact, with longer palisade cells, less spongy mesophyll, and thicker cuticle than comparable leaves from plants growing normally in deep shade. Evidence is given for the views that (1) differences in leaf expression are not predetermined by the environment of the bud during its formation the previous season, and (2) structural modifications that result when typical shade buds are suddenly exposed to full sunlight are merely an indication of the plasticity of leaves to light.
SURVIVAL AND PATHOGENICITY OFALTERNARIA RAPHANIAFTER FIVE YEARS IN DRIED SOIL CULTURES
Authors: Atkinson R. G.
Published: August 2008

Soil cultures of Alternaria raphani, a seed-borne pathogen of radish, that had become dry when four to six weeks old, were still viable after five years. The incidence of residual viable centers in cultures of four of the five wild types studied was much higher than in those of their respective variants, on the basis of colony counts from platings of 5-gm. samples diluted one-fifth. The reverse of this was true for the remaining wild type and its variant. This pair was also unique in that the wild type had been shown to possess little infectivity, whereas its variant had proved to be highly virulent. The fungus showed no change in cultural characteristics after its five-year period in dry soil, nor any loss of virulence when plants of radish, stock, and wallflower were inoculated.
FURTHER STUDIES OF BIRCH DIEBACK IN NOVA SCOTIA
Authors: Greenidge K. N. H.
Published: August 2008

Well-marked differences, involving both the patterns of moisture movement and storage, have been found to separate the water relationships of yellow birch, Betula lutea Michx., in various stages of deterioration. The cumulative results of injection studies, root excavations, and an extended survey of the trends in moisture distribution in the species over a prolonged period, suggest that the locus of action of the disease is, in the first instance, in the roots, and that excessive rootlet mortalities in apparently healthy trees constitute the initial indication of a diseased condition in the species.
CONIDIOPHORES, CONIDIA, AND CLASSIFICATION
Authors: Hughes S. J.
Published: August 2008

Characters of conidiophore and conidium development are used for the separation of some common temperate and a few tropical Hyphomycetes into eight Sections. The need for further studies on the precise method of conidium development is stressed because this promises to provide the most stable character for the classification of Fungi Imperfecti as a whole. Conidiophores and conidia of a large number of Hyphomycetes are figured to illustrate the various characters common to each Section.
PRELIMINARY STUDIES ON THE SEXUAL STAGE OF RHIZOCTONIA SOLANI KÜHN
Authors: Hawn E. J. , Vanterpool T. C.
Published: August 2008

The perfect stage of a flax strain of Rhizoctonia solani Kühn was obtained fairly consistently on artificial media. In growth characters and morphological dimensions, it agreed closely with those of Pellicularia filamentosa (Pat.) Rogers, except that its sterigmata averaged three times as long (26 μ). This latter character suggests close relationship to Corticium praticola Kotila. Single-basidiospore cultures differed among themselves and from the parent strain in morphology, cultural characters, growth rates, and pathogenicity on Royal flax. Some single-spore cultures produced the perfect stage, although preliminary pairings of sterile single-spore cultures remained sterile. This isolate is thus heterozygous and homothallic. There appear to be 12 chromosomes in the diploid nucleus in the basidium. The mature basidiospore is predominantly uninucleate; occasionally a binucleate basidiospore is observed. Germination is by repetition on plain agar, or by germ tubes on rich media. Those basidiospores which germinate by repetition are commonly uninucleate and give rise to uninucleate secondary basidiospores. Basidiospore discharge is by the drop excretion mechanism. To determine the identity of the flax strain, it will be necessary to produce the perfect stage of the flax strain on natural substrates or the perfect stage of P. filamentosa on artificial media.
A SLIDE TECHNIQUE FOR THE STUDY OF FUNGI AND ACTINOMYCETES IN SOIL WITH SPECIAL REFERENCE TO HELMINTHOSPORIUM SATIVUM
Authors: Chinn S. H. F.
Published: August 2008

A slide technique suitable for studying the behavior of fungi and actinomycetes both qualitatively and quantitatively in soil is described. Besides Helminthosporium sativum, eight other fungi and one actinomycete were used to demonstrate the applicability of the method which was used for both natural and soybean meal amended soils. In the natural soil spores of Penicillium notatum, Stachybotrys atra, and the actinomycete only germinated. However, lysis or disintegration of the germ tubes of the two fungi was observed on the fourth day. Growth of the actinomycete was continuous to at least the seventh day. In the amended soil only one fungus failed to germinate. Of those that germinated, only Fusarium culmorum and the actinomycete were capable of continued growth and sporulation. Lysis or disintegration of the germ tubes of the others was noticed on the fourth day.
STUDIES IN WOOD-INHABITING HYMENOMYCETES: I. ODONTIA BICOLOR
Authors: Nobles Mildred K.
Published: August 2008

It has been found by cultural methods that Odontia bicolor (Alb. & Schw. ex Fries) Bres. is the cause of an important butt rot in various species of coniferous and broad-leaved trees in Canada. A description of the cultural characters of the fungus and the decay from which it has been isolated is presented.
EFFECT OF AGE OF POTATO FOLIAGE ON EXPRESSION OF LEAF-ROLL SYMPTOMS
Authors: Davidson T. R. , Sanford G. B.
Published: August 2008

In an extensive experiment conducted under field conditions during four successive years, the symptoms of leaf roll of potatoes, as expressed by potato plants of various ages, were studied. Healthy plants of the varieties Netted Gem, Carter's Early Favorite, and Canus were graft-inoculated with infected scions from Canus at 10-day intervals from June 10 to September 15 and protected from viruliferous aphids by a lethal spray applied frequently. Infection of the plants was verified by the tuber-index method. On young plants leaf-roll symptoms were regularly severe and a high percentage of plants became infected. However, the severity of foliage symptoms and also the percentage of plants infected gradually decreased until about August 15. After this date the infected plants were healthy in appearance but the percentage of them actually infected continued to decline sharply. The data presented show that potato plants infected by the leaf-roll virus after midseason normally do not develop definite foliage symptoms of the leaf-roll disease and, therefore, cannot be detected by ordinary field inspection.
EFFECT OF GASEOUS ENVIRONMENT AND TEMPERATURE ON ASCOSPORE FORMATION IN SACCHAROMYCES CEREVISIAE HANSEN
Authors: Adams A. M. , Miller J. J.
Published: August 2008

The effect on ascospore formation in bakers' yeast of varying degrees of aeration and of oxygen, carbon dioxide, and nitrogen individually and in mixtures was studied. In the absence of carbon dioxide, ascospore formation was stimulated by concentrations of oxygen up to 12.0% but was depressed slightly at 41.1% and more so at 68.8% and at 100%. Carbon dioxide inhibited ascospore formation; very few were found when the carbon dioxide concentration was 25% or greater. Oxygen did not overcome the inhibitory effect of carbon dioxide. Ethyl alcohol vapor so markedly inhibited sporulation that ascospores were rarely observed in cultures exposed to the vapor from a 5% solution of ethyl alcohol. Ascospore formation was observed at. temperatures from 3.0 to 33.3 °C. Of two strains studied in one experiment, one showed highest sporulation at 24.0 °C. and the other at 27.5 °C. Cells exposed for 14 days to temperatures of 2.5, −3.5, and −18.0 °C, and cells multiplied at 37.5 °C, showed reduced sporulation at room temperature.
SYNTHESIS OF RADIOACTIVE SUCROSE BY TOBACCO LEAVES FROM C14 UNIFORMLY LABELLED GLUCOSE AND GLUCOSE-1-PHOSPHATE
Authors: Vittorio P. V. , Krotkov G. , Reed G. B.
Published: August 2008

Detached tobacco leaves were placed for six hours on solutions of C14 labelled glucose and glucose-1-phosphate. At the end of this time leaves were extracted with boiling 80% ethanol and the activities of their various carbohydrate fractions were determined. The specific activities of both glucose and fructose moieties of sucrose were found to be high and very close one to another, while that of the free fructose was low. From this it has been concluded that the fructose component of sucrose is derived from the glucose introduced and not from the free fructose present in leaves. Low activity in starch observed in photosynthesizing leaves indicates preferential transformation of the glucose introduced into sucrose and not into starch. Moreover, respiration of labelled glucose ought to produce labelled carbon dioxide, and after a period of photosynthesis, labelled starch. The isolated starch contained only a small amount of activity indicating that, in light, sugars were not utilized in respiration to any great extent. Moreover, they did in darkness, as the carbon dioxide evolved was very radioactive.
RESISTANCE OF COMMON BARBERRY (BERBERIS VULGARIS L.) TO RACE 15B OF WHEAT STEM RUST
Authors: Johnson T. , Green G. J.
Published: August 2008

Twenty-four plants of barberry, Berberis vulgaris L., were inoculated with sporidia derived from several collections of race 15B of Puccinia graminis var. tritici Erikss. & Henn. Only five small pustules of aecia were produced on these plants; all other infections were limited to small necrotic spots or very small pustules of pycnia.
OXYGEN UPTAKE BY RHIZOBIA IN SOIL
Authors: Spencer J. F. T.
Published: August 2008

Plant residues were mixed with moistened soils and the mixtures incubated at room temperature. Samples were taken at intervals of several days, steam sterilized, and used as substrates in the Lees respirometer for measurements of oxygen uptake by Rhizobium meliloti. Rhizobia were active in the soils and their activity was stimulated by addition of ordinary plant residues. It was found that the shorter the incubation period of the soil – plant residues mixture, the greater was the increase in oxygen uptake over that obtained when the soil alone was used as substrate. The Lees respirometer was found to be a convenient apparatus for measurements of oxygen uptake by soil microflora.
PHOTOPERIODIC ECOTYPES OF TREES
Authors: Vaartaja Olli
Published: August 2008

Seedlings of Pinus sylvestris L. and Alnus incana (L.) Moench. from two widely different latitudes were grown under two different photoperiods, but otherwise under optimum conditions. Under continuous light the seedlings from a far northern latitude grew better than those from a more southern latitude. This situation was reversed under short photoperiods. Since the days of the growing season at the northern latitude are extremely long and those at the southern latitude relatively short, the difference in growth of the seedlings is explained as being the result of heritable adaptation of the trees. The experimental results thus support the theory that within tree species there are "photoperiodic ecotypes" which during evolution have adapted themselves to the photoclimate of their environment.
TAXONOMY, PHYLOGENY, HOST RELATIONSHIP, AND PHYTOGEOGRAPHY OF THE MICROCYCLIC RUSTS OF SAXIFRAGACEAE
Authors: Savile D. B. O.
Published: August 2008

The microcyclic species of Puccinia on Saxifragaceae are revised in the light of abundant recent collections. Recombinations or new varieties include: P. asiatica var. tiarellae, P. heucherae var. chrysosplenii, P. h. var. austroberingiana, P. h. var. saxifragae, P. h. var. lithophragmae, P. pazschkei var. heterisiae, P. p. var. tricuspidatae, P. p. var. huteri, P. p. var. jueliana, P. p. var. oppositifoliae. The basic species appears to be P. tottoriensis, whence three evolutionary lines have given rise to: (i) P. asiatica, P. saxifragae–ciliatae, and P. laurentiana; (ii) P. heucherae and P. pazschkei; (iii) P. fischeri and P. joerstadii. The complex originated in, probably, eastern Asia. P. heucherae vars. developed in Cordilleran North America concurrently with the development of Saxifragaceae in that region. Some varieties of P. heucherae occur on several host genera, providing clues to the comparative ages of species in these genera. Since the varieties of P. heucherae and P. pazschkei can be arranged in an evolutionary sequence, clues are available as to the relative ages of various sections of Saxifraga.
THE ORGANISM CAUSING DWARF BUNT OF WHEAT
Authors: Conners I. L.
Published: August 2008

When Fischer described Tilletia brevifaciens as the organism causing dwarf bunt of winter wheat, he showed that it was specifically distinct from T. caries (Fr.) Tul. However, he failed to indicate how his new species was separated from other species of Tilletia already described. Some of these species were restudied. It has been found that Tilletia brevifaciens is not specifically distinct from T. contraversa Kühn originally described on Agropyron repens, but also known on other species of Agropyron. Wheat probably first contracted dwarf bunt in the mountainous areas of Europe, where native species of Agropyron are found naturally infected by T. contraversa. The pathogen has been introduced into North America.
STUDIES OF WESTERN TREE RUSTS: I. A NEW CONE RUST ON SITKA SPRUCE
Authors: Ziller W. G.
Published: August 2008

Local damage on the Queen Charlotte Islands to seed of Sitka spruce, Picea sitchensis, has led to the discovery of the causal agent, a new cone rust. At the same time a new Chrysomyxa on the one-flowered pyrola, Moneses uniflora, was discovered in the same area. Evidence from observations in the field, from controlled inoculations, and from the similarity of markings on aeciospores and urediniospores has led to the conclusion that the cone rust is the aecial stage of an undescribed Chrysomyxa. The rust has been described and named Chrysomyxa monesis. It is feared that the rust may cause serious damage to spruce seed abroad unless its spread is prevented. Surface sterilization of spruce seed before export is therefore recommended.
A CYTOLOGICAL STUDY OF ASCUS DEVELOPMENT IN PYRONEMA CONFLUENS TUL.
Authors: McIntosh D. L.
Published: August 2008

A cytological study of Pyronema confluens has revealed that only one meiosis occurs in the ascus, and that the haploid chromosome complement is probably 12. Differences in size and staining properties were noted between nuclei of the ascogenous hyphae and paraphyses. Diplotene chromosomes are linearly differentiated into heterochromatic knobs and achromatic intercalary segments that could not be differentiated from the cytoplasm with either basic fuchsin or propiono-carmine.