Evidence for environmental determination of uredinia and telia production in Chrysomyxa pirolata (inland spruce cone rust)

2000 ◽  
Vol 78 (5) ◽  
pp. 660-667 ◽  
Author(s):  
Patricia E Crane ◽  
Yasuyuki Hiratsuka
Keyword(s):  
Relative Humidity ◽  
Field Experiment ◽  
Sexual Reproduction ◽  
Cross Sections ◽  
Environmental Conditions ◽  
Seed Orchard ◽  
High Humidity ◽  
Light Conditions ◽  
Growing Seasons

Chrysomyxa pirolata Wint., the cause of inland spruce cone rust, is a serious pathogen in natural spruce forests and seed orchards. Cone infection is caused by basidiospores produced by telia on alternate hosts in the genera Pyrola, Moneses, and Orthilia. The disease cycle of this rust and the influence of moisture on the differentiation of telia on Pyrola asarifolia Michx. were studied over two growing seasons at a wet site adjacent to a spruce seed orchard and a drier site adjacent to another orchard at Smoky Lake, Alberta, and at Edmonton and Hinton, Alberta. The proportion of uredinia to telia varied with microsite conditions, with more frequent production of telia in moist sites. The effect of moisture on formation of telia was tested by subjecting infected plants with immature sori to 90-100% relative humidity under various temperature and light conditions. Plants under high humidity, regardless of other conditions, formed mainly telia from immature sori, even if uredinia had already formed on parts of the leaves before the experiments. Telia formation, however, was much slower at 4-6°C than at 22°C. Cross-sections of sori showed that young uredinia could sometimes convert to telia. Results of a field experiment also suggested that increasing moisture increases the percentage of telia produced on plants. The production of undifferentiated sori that can become either uredinia or telia in response to environmental conditions may allow the fungus to maximize vegetative proliferation when conditions are unfavorable for sexual reproduction. It might also explain the large variation in cone rust levels from year to year in a given location.Key words: Picea, Pyrola, telia induction, seed orchard, Uredinales.

Corrosion Analysis of a Fiber-Optic Transceiver Housing

2001 ◽  
Author(s):  
J. H. Lau ◽  
C. L. Jiaa ◽  
S. J. Erasmus
Keyword(s):  
Relative Humidity ◽  
Corrosion Rate ◽  
Cross Sections ◽  
Weight Change ◽  
Fiber Optic ◽  
Die Casting ◽  
Extinction Ratio ◽  
Optical Power ◽  
Zinc Alloy

Abstract The corrosion responses of a fiber-optic transceiver’s housing with zinc alloy die casting material are investigated in this study. Emphasis is placed on the determination of the weight change and corrosion rate of the housing when it is subjected to a 85% relative humidity and 85°C temperature (85%RH/85°C) test condition. Also, the average light optical power, receiver sensitivity, extinction ratio, and mask margin of transceiver modules subjected to 85%RH/85°C and 3.47V at 500, 1000, 1500, and 1600 hours are provided. Furthermore, metallography is performed on the surfaces and cross sections of the housing. Finally, measurements are made of the thickness of the oxide layer on the surfaces of the fiber-optic transceiver housing.

scholarly journals Development of MILIONCAST, an Improved Model for Predicting Downy Mildew Sporulation on Onions

Plant Disease ◽  
2004 ◽  
Vol 88 (7) ◽  
pp. 695-702 ◽  
Author(s):  
Tijs Gilles ◽  
Kath Phelps ◽  
John P. Clarkson ◽  
Roy Kennedy
Keyword(s):  
Relative Humidity ◽  
Environmental Conditions ◽  
Temporal Pattern ◽  
Random Model ◽  
Controlled Environment ◽  
High Humidity ◽  
Potted Plants ◽  
Effects Of Temperature ◽  
Improved Model ◽  
Accuracy Of Prediction

The effects of temperature and relative humidity on Peronospora destructor sporulation on onion (Allium cepa) leaves were studied under controlled environmental conditions. Sporangia were produced most rapidly at 8 to 12°C after 5 h of high humidity during dark periods. The greatest number of sporangia was produced at 100% relative humidity (RH), and sporulation decreased to almost nil when humidity decreased to 93% RH. A model, named MILIONCAST (an acronym for MILdew on onION foreCAST), was developed based on the data from these controlled environment studies to predict the rate of sporulation in relation to temperature and relative humidity. The accuracy of prediction of sporulation was evaluated by comparing predictions with observations of sporulation on infected plants in pots outdoors. The accuracy of MILIONCAST was compared with the accuracy of existing models based on DOWNCAST. MILIONCAST gave more correct predictions of sporulation than the DOWNCAST models and a random model. All models based on DOWNCAST were more accurate than the random model when compared on the basis of all predictions (including positive and negative predictions), but they gave fewer correct predictions of sporulation than the random model. De Visser's DOWNCAST and ONIMIL improved their accuracy of prediction of sporulation events when the threshold humidity for sporulation was reduced to 92% RH. The temporal pattern of predicted sporulation by MILIONCAST generally corresponded well to the pattern of sporulation observed on the outdoor potted plants at Wellesbourne, UK.

scholarly journals PRINCIPAL COMPONENTS OF THE INTENSITY OF SQUAMOUS ROT ON PRICKLY PEAR PLANTATIONS IN THE SEMIARID REGION OF THE STATE OF PARAÍBA, BRAZIL

2017 ◽  
Vol 30 (2) ◽  
pp. 370-376 ◽  
Author(s):  
ANNE EVELYNE FRANCO DE SOUZA ◽  
LUCIANA CORDEIRO DO NASCIMENTO ◽  
BRENO OLIVEIRA DE SOUZA
Keyword(s):  
Relative Humidity ◽  
Fungal Pathogens ◽  
The State ◽  
Prickly Pear ◽  
Semiarid Region ◽  
High Humidity ◽  
High Incidence ◽  
Severity Of The Disease ◽  
Main Components

ABSTRACT The aim of the present study was to identify fungal pathogens associated with prickly pear rot and the main components of squamous rot on plantations in the semiarid region of the state of Paraíba, Brazil. Pathogens were identified morphologically. The determination of the main components of squamous rot intensity was based on the incidence and severity of the disease. Fifteen genera of fungi were associated with rot, including Scytalidium sp., which was found on all plantations. The analyses indicated that relative humidity and rainfall favored the intensity of rot more than temperature. At least three pathogens were found to be associated with a high incidence of rot in prickly pear species in the semiarid region of the state of Paraíba, Brazil, but Scytalidium sp. was the most widely distributed. Moreover, the disease caused by this fungus intensifies and progresses under conditions of high humidity at moderate temperatures.

Corrosion Analysis of a Fiber-Optic Transceiver Housing

2002 ◽  
Vol 124 (4) ◽  
pp. 379-384
Author(s):  
J. H. Lau ◽  
C. L. Jiaa ◽  
S. J. Erasmus
Keyword(s):  
Relative Humidity ◽  
Corrosion Rate ◽  
Cross Sections ◽  
Weight Change ◽  
Fiber Optic ◽  
Die Casting ◽  
Extinction Ratio ◽  
Optical Power ◽  
Zinc Alloy

The corrosion responses of a fiber-optic transceiver’s housing with zinc alloy die casting material are investigated in this study. Emphasis is placed on the determination of the weight change and corrosion rate of the housing when it is subjected to a 85% relative humidity and 85°C temperature (85%RH/85°C) test condition. Also, the average light optical power, receiver sensitivity, extinction ratio, and mask margin of transceiver modules subjected to 85%RH/85°C and 3.47V at 500, 1000, 1500, and 1600 h are provided. Furthermore, metallography is performed on the surfaces and cross sections of the housing. Finally, measurements are made of the thickness of the oxide layer on the surfaces of the fiber-optic transceiver housing.

Analysis of STEM micrographs of thick objects

1978 ◽  
Vol 36 (2) ◽  
pp. 106-107
Author(s):  
S. Golladay
Keyword(s):  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Mass Distribution ◽  
Cross Sections ◽  
Phase Contrast ◽  
Image Point ◽  
Contrast Effects ◽  
Total Cross Sections ◽  
Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

A quantitative approach to inner shell losses

1978 ◽  
Vol 36 (1) ◽  
pp. 526-527 ◽  
Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Background Intensity ◽  
Core Excitation ◽  
Quantitative Basis ◽  
Cross Section Differential ◽  
Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

Preparation And elemental analysis of ancient fibers

1987 ◽  
Vol 45 ◽  
pp. 410-411
Author(s):  
Allen Angel ◽  
Kathryn A. Jakes
Keyword(s):  
Cross Sections ◽  
Physical Structure ◽  
Energy Dispersive ◽  
Archaeological Sites ◽  
X Ray ◽  
Long Term Storage ◽  
Backscattered Electron ◽  
Electron Imaging

Fabrics recovered from archaeological sites often are so badly degraded that fiber identification based on physical morphology is difficult. Although diagenetic changes may be viewed as destructive to factors necessary for the discernment of fiber information, changes occurring during any stage of a fiber's lifetime leave a record within the fiber's chemical and physical structure. These alterations may offer valuable clues to understanding the conditions of the fiber's growth, fiber preparation and fabric processing technology and conditions of burial or long term storage (1).Energy dispersive spectrometry has been reported to be suitable for determination of mordant treatment on historic fibers (2,3) and has been used to characterize metal wrapping of combination yarns (4,5). In this study, a technique is developed which provides fractured cross sections of fibers for x-ray analysis and elemental mapping. In addition, backscattered electron imaging (BSI) and energy dispersive x-ray microanalysis (EDS) are utilized to correlate elements to their distribution in fibers.

Gender determination of caucasoid hair using image analysis

1993 ◽  
Vol 51 ◽  
pp. 216-217
Author(s):  
T.B. Ball ◽  
W.M. Hess
Keyword(s):  
Image Analysis ◽  
Cross Sections ◽  
Scalp Hair ◽  
The Body ◽  
Equivalent Diameter ◽  
Cross Sectional ◽  
Hair Samples ◽  
Length Width ◽  
Morphological Differences

It has been demonstrated that cross sections of bundles of hair can be effectively studied using image analysis. These studies can help to elucidate morphological differences of hair from one region of the body to another. The purpose of the present investigation was to use image analysis to determine whether morphological differences could be demonstrated between male and female human Caucasian terminal scalp hair.Hair samples were taken from the back of the head from 18 caucasoid males and 13 caucasoid females (Figs. 1-2). Bundles of 50 hairs were processed for cross-sectional examination and then analyzed using Prism Image Analysis software on a Macintosh llci computer. Twenty morphological parameters of size and shape were evaluated for each hair cross-section. The size parameters evaluated were area, convex area, perimeter, convex perimeter, length, breadth, fiber length, width, equivalent diameter, and inscribed radius. The shape parameters considered were formfactor, roundness, convexity, solidity, compactness, aspect ratio, elongation, curl, and fractal dimension.

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