The human melanocyte and melanoblast populations per unit area of epidermis in the rete ridge are greater than in the inter‐rete ridge

Author(s):  
Tomohisa Hirobe ◽  
Hisao Enami ◽  
Ai Nakayama
Author(s):  
Robert M. Glaeser

It is well known that a large flux of electrons must pass through a specimen in order to obtain a high resolution image while a smaller particle flux is satisfactory for a low resolution image. The minimum particle flux that is required depends upon the contrast in the image and the signal-to-noise (S/N) ratio at which the data are considered acceptable. For a given S/N associated with statistical fluxtuations, the relationship between contrast and “counting statistics” is s131_eqn1, where C = contrast; r2 is the area of a picture element corresponding to the resolution, r; N is the number of electrons incident per unit area of the specimen; f is the fraction of electrons that contribute to formation of the image, relative to the total number of electrons incident upon the object.


Author(s):  
Elrnar Zeitler

Considering any finite three-dimensional object, a “projection” is here defined as a two-dimensional representation of the object's mass per unit area on a plane normal to a given projection axis, here taken as they-axis. Since the object can be seen as being built from parallel, thin slices, the relation between object structure and its projection can be reduced by one dimension. It is assumed that an electron microscope equipped with a tilting stage records the projectionWhere the object has a spatial density distribution p(r,ϕ) within a limiting radius taken to be unity, and the stage is tilted by an angle 9 with respect to the x-axis of the recording plane.


Author(s):  
J. Curtis ◽  
K. S. Schwartz ◽  
R. P. Apkarian

A scanning electron microscope (SEM) study was made of the effect of adrenocorticotropic hormone (ACTH) on the size and numbers of fenestrae/unit area in the capillary endothelium of the zona fasciculata (ZF) of the rat adrenal. The stimulatory effect of ACTH on cholesterol uptake via high density lipoproteins in the rat and evidence for the secretion of glucocorticoids by exocytosis of lipid droplets described by Rhodin suggest that endothelial change may accompany these transport phenomena.Twelve rats received two Dexamethasone (DEX) ip injections (25 μg DEX/100 g body wt.), the first at 8 PM and the second at 8 AM the next day, to inhibit the release of endogenous ACTH by the anterior pituitary. The animals were then divided into two groups. Six animals received only saline vehicle and six rats received ACTH (100 ng/100 g body wt.).


Author(s):  
George H. Herbener ◽  
Antonio Nanci ◽  
Moise Bendayan

Protein A-gold immunocytochemistry is a two-step, post-embedding labeling procedure which may be applied to tissue sections to localize intra- and extracellular proteins. The key requisite for immunocytochemistry is the availability of the appropriate antibody to react in an immune response with the antigenic sites on the protein of interest. During the second step, protein A-gold complex is reacted with the antibody. This is a non- specific reaction in that protein A will combine with most IgG antibodies. The ‘label’ visualized in the electron microscope is colloidal gold. Since labeling is restricted to the surface of the tissue section and since colloidal gold is particulate, labeling density, i.e., the number of gold particles per unit area of tissue section, may be quantitated with ease and accuracy.


1997 ◽  
Vol 40 (2) ◽  
pp. 400-404 ◽  
Author(s):  
Virginia A. Hinton ◽  
Winston M. C. Arokiasamy

It has been hypothesized that typical speech movements do not involve large muscular forces and that normal speakers use less than 20% of the maximum orofacial muscle contractile forces that are available (e.g., Amerman, 1993; Barlow & Abbs, 1984; Barlow & Netsell, 1986; DePaul & Brooks, 1993). However, no direct evidence for this hypothesis has been provided. This study investigated the percentage of maximum interlabial contact pressures (force per unit area) typically used during speech production. The primary conclusion of this study is that normal speakers typically use less than 20% of the available interlabial contact pressure, whether or not the jaw contributes to bilabial closure. Production of the phone [p] at conversational rate and intensity generated an average of 10.56% of maximum available interlabial pressure (MILP) when jaw movement was not restricted and 14.62% when jaw movement was eliminated.


1970 ◽  
Vol 09 (01) ◽  
pp. 84-94
Author(s):  
G. Muehllehner

SummaryThe diverging collimator makes it possible to increase the field of view of a radioisotope imaging camera. The larger field of view is obtained by sacrificing efficiency per unit area of the field of view while preserving the resolution of the system. This situation is analogous to that of the scanner, where the efficiency per unit area is inversely proportional to the total area scanned.Efficiency and resolution of diverging collimators can be calculated quite accurately as is evidenced by the good agreement between calculated and measured values. The problem of septum penetration, however, needs to be further investigated for both parallel-hole as well as diverging collimators, so that the influence of the shape and arrangement of the holes upon septum penetration is taken into account.


Author(s):  
A.V. Konstantinovich ◽  
◽  
A.S. Kuracheva ◽  
E.D. Binkevich

In conditions of climate change, when temperature and precipitation fluctuations occur more and more frequently during the growing season, it is necessary to obtain high quality seedlings with "immunity" to various stress factors, including high weediness, the damage from which is associated with a decrease in yield (by 25 -35%) and with a deterioration in the quality of agricultural products. Due to the imbalance in production technology, seedlings are often weakened, overgrown, with a low yield per unit area and survival rate in the field. One of the solutions to this problem is the use of PP for pre-sowing seed treatment to increase the competitiveness of seedlings in the field.


Author(s):  
А. I. Grabovets ◽  
V. P. Kadushkina ◽  
S. А. Kovalenko

With the growing aridity of the climate on the Don, it became necessary to improve the methodology for conducting the  breeding of spring durum wheat. The main method of obtaining the source material remains intraspecific step hybridization. Crossings were performed between genetically distant forms, differing in origin and required traits and properties. The use of chemical mutagenesis was a productive way to change the heredity of genotypes in terms of drought tolerance. When breeding for productivity, both in dry years of research and in favorable years, the most objective markers were identified — the size of the aerial mass, the mass of grain per plant, spike, and harvest index. The magnitude of the correlation coefficients between the yield per unit area and the elements of its structure is established. It was most closely associated with them in dry years, while in wet years it decreased. Power the correlation of the characteristics of the pair - the grain yield per square meter - the aboveground biomass averaged r = 0.73, and in dry years it was higher (0.91) than in favorable ones (0.61 - 0.70) , between the harvest and the harvest index - r = 0.81 (on average). In dry years, the correlation coefficient increased to 0.92. Research data confirms the greatest importance of the mass of grain from one ear and the plant in the formation of grain yield per unit area in both dry and wet years. In dry years, the correlation coefficient between yield and grain mass per plant was on average r = 0.80; in favorable years, r = 0.69. The relationship between yield and grain mass from the ear was greater — r = 0.84 and r = 0.82, respectively. Consequently, the breeding significance of the aboveground mass and the productivity of the ear, as a criterion for the selection of the crop, especially increases in the dry years. They were basic in the selection.


Author(s):  
A. A. Torop ◽  
V. V. Chaykin ◽  
E. A. Torop ◽  
I. S. Brailova ◽  
S. A. Kuzmenko

We compared peculiarities of the production process of the older and modern(created 80 years after) sorts of winter rye. It is determined that the specific coenotic productivity of a modern sort is 60.6% higher.This increase is due to higher number of productive sprouts per unit area and higher sprout weight. The coenosis of modern sorts is highly resistant to lodging. The modern sort has a 33.5% higher leaf surface index and a 17.7% higher share of the leaves in the upper tier, differing in their erectile orientation in space. As for the content of total chlorophyll in the dry matter of leaves and vagina, the modern sort is inferior to the older by 30.2%during theearing period, and by 17.5%during the milky-wax ripeness period.As for the content of total chlorophyll in the sowing area, the compared sorts were practically the same, but the ratio between chlorophyll a and c was noticeably different. As for the chlorophyll content in stems, in dry matter and in the area of ​​sowing, the modern sort is inferior by1.5 times and more to the older in both observation terms. The sorts differed in the biomass accumulation and its distribution between the parts during the vegetation period. To establish the ear productivity, the older sort used only the current photosynthesis products.In conditions of an unfavorable growth year, the modern sort used previously accumulated by leaves and re-utilized assimilates. The actual and potential productivity of an ear in a modern sort is higher by 77.4 and 68.0%, respectively, but the degree of its vegetative mass supply is lower by 48.6%.Only due to the higher, by 77.4%, utilization of the mass of the sprout, the modern sort binds a greater number of grains in the ear with a higherseparate mass.Since the sharp increase in the ear productivity potential was not accompanied by the same growth of the sprout vegetative mass, the modern sort, in unfavorable conditions for growth, has tensions in the relation system between the sprout vegetative mass and pouring grain. This may be the reason of the unstable achievedyield level.


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