Intermediate Growth Stages Research Articles

Follicular growth and atresia in the ovaries of hens (Gallus domesticus) with diminished egg production rates.

Diets containing 3.5, 1.0 and 0.1% calcium were fed from the age of 42 weeks to individually caged laying hens. Ovaries were examined at 46-49 and 70 weeks of age for changes in the follicular population corresponding to the lowered egg production rates of birds given calcium-deficient diets (1.0% and 0.1%) and older birds given a normal diet (3.5%). Growth rates of follicles from 3.5 mm diameter to ovulation were not changed by the level of dietary calcium in 46-49-week-old birds. The number of atretic small follicles (less than or equal to 8 mm diam.) increased in old and calcium-deprived birds, resulting in lower numbers of viable follicles in the intermediate stages of growth (3-8 mm diam.). There was also an increase in the number of small follicles (1-2 mm diam.) starting to grow in 70-week-old birds which may have partly compensated for the increased loss by atresia. Birds of all ages on all diets were able to produce large follicles up to ovulable size. The main feature of poor laying birds was a reduction in the ovulation rate due to the loss of large follicles (greater than 8 mm diam.) by atresia, an event seen rarely in the birds with good laying performance. As atresia is the normal fate of most of the small follicles, the mechanisms controlling atresia in the small follicles and the large follicles appear to be independent.

The simulation of thin film growth

The simulation of the intermediate stage of thin film growth is described. The change in the condensation coefficient on the free surface and the randomness of the initial distribution of nuclei (shown by the effects on the capture area) were studied. The time dependences of the coverage and of the integral condensation coefficient, the histograms of the island radii and of the distances to nearest neighbours etc. were obtained. The results derived show that the Monte Carlo method could be successfully used for this type of physical problem.

Characterization of spherulite boundaries and general observations of solvent action on crystallized polypropylene and polybutene

As part of a general study of the electrical properties of thin polymer films swollen by dielectric liquids, the crystallization dynamics, final morphology and the intermediate stages of spherulitic growth in polypropylene and polybutene have been studied, along with the optical effects of solvent action. These studies have helped to clarify the action of an impregnant on a polymer film and to visualize which regions are dissolved by the solvent and hence where it resides after impregnation is completed.

The effect of time of initial defoliation and height of defoliation on the productivity of perennial ryegrass swards

AbstractOver a 3‐year period the productivity of perennial ryegrass (Lolium perenne L., cv. S24) swards as influenced by variations in the time of initial defoliation and close (2·5 cm) and lax (8 cm) defoliation was studied. Treatments with initial defoliations in the early vegetative stage, stem elongation and flowering stages of growth gave higher annual yields than treatments in which the initial defoliation was taken at an intermediate stage of growth when the majority of the stem apices had just been elevated above the height of defoliation. Initial defoliation treatments which removed a high proportion of apical meristems while the yield at the initial defoliation was still low produced the lowest annual yield. Consistent lax defoliation reduced yield by 14·5% compared with continual close defoliation. However, taking an initial lax defoliation followed by subsequent close defoliations produced a slight yield advantage of 4·8% over consistent close defoliation. The results are discussed in relation to other research findings and the practical implications commented upon.

Method for determination of coefficient of surface self-diffusion and adhesion energy of evaporated material

A simple model of the intermediate stage of thin film growth was established for the case of the three-dimensional growth. In this stage, the film growth is strongly influenced by the growth and the coalescence of islands, often occurring via the so-called liquid-like manner; this process is controlled by the surface self-diffusion of evaporated material. Thus, the characteristic of thin film in this stage measured experimentally, can be employed for the determination of some parameters: the coefficient of surface self-diffusion Ds = D0 exp (-Qs/kT), especially activation energy Qs and pre-exponential factor D0 of the evaporated material and adhesion energyβ for the system film/substrate.

Bubble nucleation; static forces in hollow-half-bubbles

It is suggested that the nucleation of bubbles may proceed through an intermediate stage of formation and growth of hollow-half-bubbles. The hollow-half-bubble can be formed by a simple, continuous deformation of the magnetization in the film. The inner wall repels the outer wall and facilitates its expansion. The inner wall is not stable, but the contractive driving force is relatively small. Hence, particularly in the presence of coercivity, the inner wall may survive sufficiently long to stabilize the outer wall. A transparent graphical analysis of the stability conditions of each wall is given.

Temperature-sensitive developmental mutants of Caenorhabditis elegans

About 200 temperature-sensitive mutants of the nematode Caenorhabditis elegans have been isolated. At restrictive temperature, the mutants are blocked in the reproductive life cycle. They have been placed into six broad categories based on their defective phenotypes. The six categories are: (1) mutants blocked in embryogenesis; (2) mutants defective in gonadogenesis; (3) mutants defective in spermatogenesis; (4) mutants that accumulate at an intermediate growth stage; (5) mutants that produce sterile adult progeny; (6) mutants that have a temperature-sensitive morphological defect that interrupts the reproductive life cycle. The critical times of temperature sensitivity have been measured using temperature-shift experiments. Most of the gonadogenesis and spermatogenesis mutants are temperature sensitive during the period of cellular differentiation rather than proliferation. The temperature responses of the gonadogenesis and zygote-defective mutants indicate a common association between functions in gonadogenesis and early embryogenesis. Many of the mutants placed in different categories share other temperature-sensitive phenotypes upon close examination. This implies that many of the functions required for development are general metabolic reactions under increased demand during differentiation and embryogenesis.

ONTOGENETIC REORGANIZATION OF THE ROOT MERISTEM IN THE COMPOSITAE

The organization of the root meristem in selected Compositae was investigated to determine whether changes in the pattern of cell arrangement occurred during root growth in species other than Helianthus annuus. Embryonic, short, and long primary roots of one species of each of twelve genera were prepared for microscopic examination. Additional intermediate growth stages were prepared for Echinacea pallida. The meristem of embryonic roots showed layers of initials typical for dicotyledons. The meristem in many of the short roots of eight species was reorganized by the development of a secondary columella. The long roots showed patterns similar to the embryonic roots. In three species which maintained closed meristems, two layers of cortical initials were common in the embryonic root, and as a general trend, a single layer of cortical initials became more common during root elongation. The cellular changes that resulted in the initiation of a secondary columella are characterized by the conversion of cortical initials to secondary columella initials by a shift in their plane of cell division. It is proposed that the size and shape of the quiescent center changes as the conversion takes place. No intermediate stages were observed which could account for the reduction of two layers of cortical initials to one layer.

Ontogenetic Reorganization of the Root Meristem in the Compositae

The organization of the root meristem in selected Compositae was investigated to determine whether changes in the pattern of cell arrangement occurred during root growth in species other than Helianthus annuus. Embryonic, short, and long primary roots of one species of each of twelve genera were prepared for microscopic examination. Additional intermediate growth stages were prepared for Echinacea pallida. The meristem of embryonic roots showed layers of initials typical for dicotyledons. The meristem in many of the short roots of eight species was reorganized by the development of a secondary columella. The long roots showed patterns similar to the embryonic roots. In three species which maintained closed meristems, two layers of cortical initials were common in the embryonic root, and as a general trend, a single layer of cortical initials became more common during root elongation. The cellular changes that resulted in the initiation of a secondary columella are characterized by the conversion of cortical initials to secondary columella initials by a shift in their plane of cell division. It is proposed that the size and shape of the quiescent center changes as the conversion takes place. No intermediate stages were observed which could account for the reduction of two layers of cortical initials to one layer.

Theoretical Aspects of the Peltier Effect on the Temperature Distribution in Crystal Grown by the Czochralski Technique

A theoretical treatment is given for the temperature distribution in a Czochralski system with and without the presence of the Peltier effect. The effect of Peltier heating on the crystal diameter during growth is also considered. The results indicate that the Peltier current necessary to control a given diameter of a crystal during intermediate stages of growth is dependent on , the crucible temperature, and , the height of crucible above the melt.

Pathogenicity of Pythium spp. And Phytopththora drechsleri to Eucalyptus spp

A number of Pythium spp, and Phytophthora drechsleri have been associated with Phytophthora cinnamomi in the die-back disease of eucalypts in forests of southern and eastern Australia. Although P. cinnamomi is generally considered to be the most important pathogen causing root rot and die-back, there is some uncertainty whether it is the only pathogen. The pathogenicity of Pythium ultimum, P. irregulare, P. debaryanum, P. vexans, P. mamillatum, three unidentified Pythium species from eucalypt forest soil and Phytophthora drechsleri was compared with that of Phytophthora cinnamomi on juvenile and intermediate-aged seedlings of Eucalyptus sieberi and juvenile seedlings of other eucalypt species. Of the Pythiums, only P. ultimum, P. irregulare and P. debaryanum could kill small juvenile seedlings at the two-leaf stage of development. Neither any of the Pythiums nor Phytophthora drechsleri could kill E. sieberi at the intermediate growth stage. In marked contrast, Phytophthora cinnamomi showed considerable pathogenicity, killing seedlings and saplings with rapidity. The unidentified Pythium spp, from native forests were completely innocuous.

Physical mechanisms in carbon formation in flames

A molecular beam-sampling system, combined with electrical deflection of the beam andelectron microscope analysis of beam deposits, was used to measure the size, size distribution, number concentration, and fraction charged of carbon particles down to about 15diam in a flat acetylene-oxygen flame at 20 mm Hg. Coagulation of carbon particles occurs at all positions sampled in the flame, which process combines with surface growth to form particle clusters that gradually change from roughly spherical, at early and intermediate stages of growth, to chainlike in the flame tail. Particle-diameter distributions, in which chainlike clusters are assigned the volume-equivalent sphere diameter, progress from being mainly Gaussian in the early stages of carbon formation to mainly lognormal in the later stages. The particle number concentration increases rapidly to a peak value at an early stage, and decreases thereafter. The rate of nucleation and coagulation each exhibit a maximum approximately 6 msec after the onset of carbon formation and, using the same time reference, the rate of surface growth decreases approximately linearly from about 20 /sec at the first sampling point (1.67 msec) to zero at about 10 msec. In the early stages of carbon formation, nucleation is fast relative to coagulation and the rate of increase of mean particle radius is considerably less than the surface growth rate. This is later reversed when coagulation rules. The number fraction of charged particles is 10% to 40%. The measured coagulation rate constant agrees with the theoretical value if the increase due to Van der Waals and electrical forces is a factor of about 30. Electrostatic interaction between particles is responsible for the formation of particle clusters in chains instead of more-compact shapes.

Light intensity and the growth of Eucalyptus seedlings. I. Ontogenetic variation in E. fastigata

Morphological and physiological variation associated with ontogenetic development is described for E. fastigata and their significance in ecology is discussed. Juvenile, intermediate, and adult leaf stages are identified. These differ in such morphological characteristics as leaf orientation, shape, thickness, chlorophyll content, and anatomical structure (including size, abundance, and distribution of stomata), all details which, in juvenile and intermediate leaves at least, are modified by the light climate under which the plants are grown. There are also significant physiological differences between juvenile and intermediate growth stages, particularly as concern apical dominance and rates of apparent photosynthesis, and modification of these by light climate. A comparison of juvenile and intermediate leaves shows that the former possess a number of features which should permit them to function better in conditions of low light intensity but, contrary to such expectations, rates of apparent photosynthesis are higher in intermediate leaves. That this is so is, it is suggested, due to differences in photosynthetic enzyme activity, an hypothesis which has not been investigated.

Histology of the oviduct of the leopard frog, Rana pipiens.

AbstractThe first one to three mm of each of the paired female oviducts in Rana pipiensconsists of a folded mucosa lacking tubular glands and enclosed by a serosa. Most of the remainder of the oviduct is lined by a folded mucosa richly endowed with simple tubular, jelly‐secreting glands. The final one to two cm of the uterine portion of the oviduct, however, has a smooth mucosal lining which lacks tubular glands. Jelly‐secreting glands penetrate to the base of the mucosa and open to the lumen between ridges capped with ciliated or mucous secreting epithelial cells. As cells of the jelly‐secreting glands grow and differentiate during the summer, they accumulate a granular secretory product which exhibits basohpilia in hematoxylinstained specimens. This is the essential change in the histological structure of the gland throughout the growing season.The adult male oviduct is a solid cord of cells for about one‐third of its length. The inferior two‐thirds, however, is like the female oviduct at an intermediate stage of seasonal growth with gland cells containing secretory granules which exhibit basophilia.

Morphology and growth of extended chain crystals of polyethylene

AbstractThe morphology and growth of extended chain crystals of polyethylene is discussed on the basis of optical and electron microscopy. The spherulitic habit is shown to be caused by nucleation of new lamellae on the (001) surface of lamellae, branching of lamellae on their growth face, and thickening of lamellae. Spherulite centers have been identified down to the primary lamella. Analysis of intersections of lamellae during crystallization allowed the identification of intermediate stages of crystal growth. Fracture surfaces parallel to the growth face and the (001) face are discussed. “Ripple decoration” by surface recrystallization is developed as a tool for fracture surface study. Kink bands are described as growth defects. Bending of lamellae is shown to go by slip parallel to the polymer chains. Ripple and drawn out fiber annealing is analyzed. All observations on extended chain crystals are used to propose a mechanism of extended chain crystal growth of polyethylene under elevated pressur.

軟鋼の溶着部,熱影響部における疲れ強さに関する研究

It is well known that the fatigue strength of welded part reduces to almost half that of base metal of a mild steel. The conceivable factors to reduce the fatigue strength of welded part are the metallugical discontinuity and the stress concentration at the toe, the undercut of reinforcement etc.In this study, basic experiments were carried out with small notched plate specimens subjected to plane bending in order to determine whether the metallugical discontinuity or the stress concentration at welded joint plays more important parts on their fatigue strength. The notch was located respectively at the base metal, the weld metal and the heat-affected zone (fine-grained zone, spheroidized pearlite zone and embrittled zone) of butt welded joint, the reinforcement cut off by machine.From the test results, it is clear that the fatigue strengths of weld metal and heat-affected zone are larger than that of base metal unless they contain defects like a notch (Fig. 8). The weld metal and heat affected zone are more notch-sensitive than the base metal, especially the spheroidized pearlite zone (Fig.10). The rate of crack propagation on respective zones is less in the intermediate stage of stationary crack growth because of work hardening, while it is large at the initial stage of crack and the prior stage to fracture. The fatigue strength of welded parts depends on the rate of crack propagation in the stationary stage and the crack propagation rate is largest in the spheroidized pearlite zone of welded part (Figs.14, 15). This fact corresponds to the lowest fatigue strength of this structure. It is observed by microscope that the cracks in the heat-affected zone propagate along grain boundary more remarkably than those on base metal.

THE EFFECTS OF SUB‐LETHAL DOSES OF MCPA ON THE MORPHOLOGY AND YIELD OF VEGETABLE CROPS

Summary. The effect of sub‐lethal doses of MCPA‐sodium on the growth, yield and marketability of summer cabbage lettuce was studied in seventeen replicated field experiments.Initial epinasty was produced by doses as low as 0.002 lb/ac a.e., and formative effects of the leaves developed at doses below 0.01 lb/ac. In plants treated at early or intermediate growth stages, two distinct types of formative effects occurred, With doses in the range 0.0025‐0.03 lb/ac, a zone of characteristic abnormal leaves developed. This reduced the marketability of the crop and the maturity was delayed, but the weight per plant at harvest was not affected. At higher doses these a abnormal leaves were not evident but the whole plant became distorted, growth was suppressed and few marketable plants were produced. In plants treated at the hearting stage, plant weight and maturity were not affected, but the marketability was reduced at doses of 0.01 lb/ac and above. The effects produced by MCPA in cos and curly crisp lettuce were compared with those produced in cabbage lettuce.

Immunity to Challenging Infections of Litomosoides carinii Produced by Transfer of Developing Worms

Previous experiments with Litomosoides carinii, the filarial worm of the cotton rat, have shown that worms of an infection produced by subcutaneous introduction of infective larvae are retarded in growth and development when the infection is superimposed on an existing infection produced by the same means (Macdonald and Scott, 1953). Other experiments have shown that when the primary infection is produced by surgical transfer of fourth-stage larvae or young adult worms, the retardation of growth of a subsequent infection produced by subcutaneous introduction of infective larvae is vary mucnl less than in the previous case (Scott et al, 1956). The present experim nts were undertaken to determine the effect of primary infections produced by transfer of worms in an intermediate growth stage, namely those in the late third larval stage. A preliminary account of these experiments has been presented by Scott and Macdonald (1956). For purposes of discussion, we are calling this retardation of growth and developmen. an expression of immunity. In this paper the words immune and immunize will be used only in this sense.

Effect of Soil Type, Fertilization, and Stage of Growth on Yield, Chemical Composition, and Biological Value of Ladino Clover (Trifolium repens L.) and Alfalfa (Medicago sativa)1

SynopsisIn a 4‐year Wisconsin study, greatest yields resulted on Miami silt loam and from cutting at intermediate growth stage. Yield increases from fertilization were greatest on soil types of lower productivity field rating. Highest contents of P, K and N resulted in forage harvested on soil types of medium to high ratings, and from pasture stage harvests. Contents of P and K were increased, Ca decreased, and N unchanged by fertilization. Forage nutritive value measured in guinea pig feeding trials compared closely to field ratings of the soil types.