scholarly journals Morphological Studies on the Epididymal Duct of the One-Humped Camel (Camelus Dromedaries)

2012 ◽  
Vol 02 (04) ◽  
pp. 245-254
Author(s):  
Ahmed E. Zayed ◽  
Khaled Aly ◽  
Ismail A. Ibrahim ◽  
Fatma M. Abd El-Maksoud
Keyword(s):  
Morphological Studies ◽  
The One ◽  
Epididymal Duct

scholarly journals Morphological studies on the seasonal changes in the epididymal duct of the one-humped camel (camelus dromedarius)

2012 ◽  
Vol 2 (1) ◽  
pp. 3 ◽  
Author(s):  
Ahmed El-Zuhry Zayed ◽  
Khaled Hamdy Aly ◽  
Ismael Abdel-Aziz Ibrahim ◽  
Fatma Mohammed Abd El-maksoud
Keyword(s):  
Morphological Changes ◽  
Reproductive Activity ◽  
Terminal Segment ◽  
Elastic Fibers ◽  
Muscular Coat ◽  
Morphological Studies ◽  
Different Seasons ◽  
Electron Microscopical ◽  
The One ◽  
Epididymal Duct

The present work was carried out on 20 testes and epididymis of sexually mature camels to elucidate the gross anatomical, morphometerical, light microscopical and scanning electron microscopical features of the epididymis in different seasons. Anatomically, the epididymal duct of a camel consists of three parts head, body and tail. Histomorphologically, the epididymal duct is subdivided into initial, middle and terminal segments, of which the middle segment is further subdivided into proximal, intermediate and distal parts. There is a gradual decrease in the epithelial height of the epididymal duct from the initial to the terminal segments. This mechanically facilities passage of the sperms toward the terminal segment. High epithelium in the initial segment may indicate a more absorptive power of the epithelium in this segment. The seasonal reproductivety of the epididymal duct in the camel expressed by variations in the weight and volume of the epididymis, total diameter of the epididymal duct, epithelial height, length of the stereocilia, thickness of the muscular coat and cellular distributions in different segments. The spring months offer ideal circumstances for maximal reproductive activity in this species. The cellular components of the epididymal duct epithelium of the camel displays important morphological changes from season to another showing signs of increasing activity during spring in comparison to decreasing activity in other seasons. PAS positive granules are demonstrated in different segments of the epididymal duct and intraepithelial glands in different seasons. These granules are relatively more numerous in spring. The lamina propria surrounding the epididymal duct contains a layer of the elastic fibers which is very thick in winter, thick in spring and thin in other seasons. This increase in thickness of the elastic fibers predisposes for the increase in the total diameter of the epididymal duct in spring. It was conclude that the muscular coat of the middle and terminal segments is the thickest in spring that may be helpful for powerful ejaculation.

The taxonomic value of floral characters in tribe Trigonelleae (Leguminosae), with special reference to Medicago

1981 ◽  
Vol 59 (9) ◽  
pp. 1578-1598 ◽  
Author(s):  
Ernest Small ◽  
C. W. Crompton ◽  
Brenda S. Brookes
Keyword(s):  
Monotypic Genus ◽  
Agglomerative Clustering ◽  
Generic Delimitation ◽  
Taxonomic Analysis ◽  
Morphological Studies ◽  
Medicago Arborea ◽  
The One ◽  
Floral Characters ◽  
Wing Petal ◽  
Floral Syndrome

The legume tribe Trigonelleae comprises Medicago (with M. arborea sometimes segregated as the monotypic genus Rhodusia), Melilotus, Trigonella, and the monotypic Factorovskya. The wisdom of segregating the two monotypic genera may be questioned, and many species have been claimed to represent intergrading variation between Medicago and either Melilotus or Trigonella, or between the latter pair. Previous morphological studies have not provided a satisfactory means of resolving generic delimitation in the Trigonelleae. In the present investigation numerical taxonomic analysis (agglomerative clustering and ordination) of floral characters indicated that Medicago, Melilotus, and Trigonella could be distinguished on the basis of combinations of floral attributes, although no single characteristic was capable of separating them completely. Trigonella section Bucerates proved to be quite distinctive from the remaining species of Trigonella examined. Limited evidence was found for segregating Medicago arborea as a monotypic genus. Factorovskya aschersoniana proved distinctive, but its relationships remain enigmatic. Discriminant analysis was employed to test the affinities of "problematical" species allegedly intermediate between Medicago, Trigonella, and Melilotus. Most of the putatively intermediate species proved to be much closer to one of the genera than to the others. A syndrome of morphological features was discovered to separate the Trigonelleae into two classes of plants, the one group including Medicago, Factorovskya, and Trigonella section Bucerates, and the other comprising Melilotus and the remaining examined species of Trigonella. The former group contrasts with the latter by possessing interlocking wing and keel petals, relatively less apical fusion of the keel petals, and relatively well-developed wing petal horns; and by having a greater frequency of species with dilated filaments, with staminal tubes which are conical at the apex rather than blunt, and with standard petals having more than three clusters of veins. The latter three differences, however, are less frequent between the two groups than the first three. The floral syndrome could reflect adaptation of the former group of plants to outcrossing (perhaps relictual adaptation in the inbreeding species) by means of the "tripping" mechanism which is well-known in Medicago. If so, the taxonomic significance of the syndrome is difficult to ascertain, as it may have developed independently in the different genera in which it occurs.

scholarly journals Resistance & Permanence of Green Urban Systems in the Globalization Age

2017 ◽  
Author(s):  
Rita Occhiuto
Keyword(s):  
New York ◽  
Public Space ◽  
Spatial Coherence ◽  
Space Structure ◽  
Urban Environments ◽  
The Other ◽  
Urban Systems ◽  
Morphological Studies ◽  
Other Hand ◽  
The One

Rita Occhiuto Faculté d’Architecture. Université de Liège, ULG. 1, Rue Courtois 4000 Liège (BE) Tél. +3242217900   e-mail : [email protected] Keywords: public space, park system, green and water infrastructure, morphological green writings, landscape memory The rapid transformation and the trivialization of landscapes in Wallonia (BE), require reformulating tools and objectives of morphological studies. Built fabrics and landscapes show the effects of abandoning or losing interest in the interrelations between natural and human actions. This contribution focuses on studies of cities and territories that have ceased to be the object of spatial policies attentive to the relationship between the need to live, maintain or care for green or natural spaces. After the systematic reduction of urban environments to simple green covers, morphological reading allows the recognition of traces of park systems or green infrastructures, whose communities often do not remember. The research's focus has shifted from the building to the green space structure. This displacement of interest makes it possible to find commons cultures that have acted on the territory of Liège (industrial city) on the one hand, through the building’s extension and on the other hand, through the project of forests, walks, squares, parks and public gardens. Now, these fragmented places become the main resource for reorganizing natural and human systems in order to offer new - social and spatial - coherence for tomorrow. Thus the historical green systems become a strong structuring link which serves to seek new dialectics of balance between existing fabrics and green systems. This system’s regeneration stands, on the one hand, to the hybridization of materials - water, green and buildings - and, on the other hand, to the physical and mental memory of the inhabited environments that populations keep. Green systems impose themselves as powerful vectors for the construction of new socio-spatial balances of cities and territories of globalization, as in the study case for the landscape systems in Liège and for the water and landscapes infrastructure in Chaudfontaine.References Foxley, A. (2010), Distance & engagement. Walking, thinking and making landscape. Vogt landscape architects, Lars Müller Publishers Cronon,W., Coll., Uncommon ground. Rethinking the Human Place in Nature. W.W.Norton & Company New York/London McHarg, I.(1969), Design with Nature, 1th, New York Spirn, A.W. (1994), The granite garden. Urban Nature and Human Design, ed. Basic Book Ravagnati, C. (2012), L’invenzione del Territorio. L’atlante inedito di Saverio Muratori, ed. Franco Angeli, Milano 

Note on Selection of Coordinate Systems for Geodynamics

1975 ◽  
Vol 26 ◽  
pp. 395-407
Author(s):  
S. Henriksen
Keyword(s):  
Sea Level ◽  
The Other ◽  
Coordinate Systems ◽  
Mean Sea Level ◽  
The Earth ◽  
The One ◽  
Static Systems ◽  
Selection Of

The first question to be answered, in seeking coordinate systems for geodynamics, is: what is geodynamics? The answer is, of course, that geodynamics is that part of geophysics which is concerned with movements of the Earth, as opposed to geostatics which is the physics of the stationary Earth. But as far as we know, there is no stationary Earth – epur sic monere. So geodynamics is actually coextensive with geophysics, and coordinate systems suitable for the one should be suitable for the other. At the present time, there are not many coordinate systems, if any, that can be identified with a static Earth. Certainly the only coordinate of aeronomic (atmospheric) interest is the height, and this is usually either as geodynamic height or as pressure. In oceanology, the most important coordinate is depth, and this, like heights in the atmosphere, is expressed as metric depth from mean sea level, as geodynamic depth, or as pressure. Only for the earth do we find “static” systems in use, ana even here there is real question as to whether the systems are dynamic or static. So it would seem that our answer to the question, of what kind, of coordinate systems are we seeking, must be that we are looking for the same systems as are used in geophysics, and these systems are dynamic in nature already – that is, their definition involvestime.

Fine Structural Localization of Acyltransferases Involved in Lipid Synthesis in Intestinal Mucosa.

1970 ◽  
Vol 28 ◽  
pp. 54-55
Author(s):  
R. J. Barrnett ◽  
J. A. Higgins
Keyword(s):  
Smooth Endoplasmic Reticulum ◽  
Lipid Synthesis ◽  
Mucosal Cell ◽  
Structural Localization ◽  
Morphological Studies ◽  
Mucosal Cells ◽  
Initial Appearance ◽  
Sh Group ◽  
Hydrolysis Of ◽  
Intestinal Mucosal Cells

The main products of intestinal hydrolysis of dietary triglycerides are free fatty acids and monoglycerides. These form micelles from which the lipids are absorbed across the mucosal cell brush border. Biochemical studies have indicated that intestinal mucosal cells possess a triglyceride synthesising system, which uses monoglyceride directly as an acylacceptor as well as the system found in other tissues in which alphaglycerophosphate is the acylacceptor. The former pathway is used preferentially for the resynthesis of triglyceride from absorbed lipid, while the latter is used mainly for phospholipid synthesis. Both lipids are incorporated into chylomicrons. Morphological studies have shown that during fat absorption there is an initial appearance of fat droplets within the cisternae of the smooth endoplasmic reticulum and that these subsequently accumulate in the golgi elements from which they are released at the lateral borders of the cell as chylomicrons.We have recently developed several methods for the fine structural localization of acyltransferases dependent on the precipitation, in an electron dense form, of CoA released during the transfer of the acyl group to an acceptor, and have now applied these methods to a study of the fine structural localization of the enzymes involved in chylomicron lipid biosynthesis. These methods are based on the reduction of ferricyanide ions by the free SH group of CoA.

Chromic Acid Etching of Polyethylene

1973 ◽  
Vol 31 ◽  
pp. 72-73
Author(s):  
J. D. Muzzy ◽  
R. D. Hester ◽  
J. L. Hubbard
Keyword(s):  
Chromic Acid ◽  
Low Cost ◽  
Acid Etching ◽  
Crystalline Morphology ◽  
Bulk Specimen ◽  
Morphological Studies ◽  
Perfect Form ◽  
Molecular Length ◽  
Lamellar Texture ◽  
Cost Studies

Polyethylene is one of the most important plastics produced today because of its good physical properties, ease of fabrication and low cost. Studies to improve the properties of polyethylene are leading to an understanding of its crystalline morphology. Polyethylene crystallized by evaporation from dilute solutions consists of thin crystals called lamellae. The polyethylene molecules are parallel to the thickness of the lamellae and are folded since the thickness of the lamellae is much less than the molecular length. This lamellar texture persists in less perfect form in polyethylene crystallized from the melt.Morphological studies of melt crystallized polyethylene have been limited due to the difficulty of isolating the microstructure from the bulk specimen without destroying or deforming it.

Nucleation of Disorder in Fe3Al Alloys

1967 ◽  
Vol 25 ◽  
pp. 312-313
Author(s):  
P. R. Swann ◽  
W. R. Duff ◽  
R. M. Fisher
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Annealing Temperature ◽  
Antiphase Domain ◽  
Effect Of Temperature ◽  
Domain Structures ◽  
Transmission Electron ◽  
Domain Boundaries ◽  
Higher Temperature ◽  
The One

Recently we have investigated the phase equilibria and antiphase domain structures of Fe-Al alloys containing from 18 to 50 at.% Al by transmission electron microscopy and Mössbauer techniques. This study has revealed that none of the published phase diagrams are correct, although the one proposed by Rimlinger agrees most closely with our results to be published separately. In this paper observations by transmission electron microscopy relating to the nucleation of disorder in Fe-24% Al will be described. Figure 1 shows the structure after heating this alloy to 776.6°C and quenching. The white areas are B2 micro-domains corresponding to regions of disorder which form at the annealing temperature and re-order during the quench. By examining specimens heated in a temperature gradient of 2°C/cm it is possible to determine the effect of temperature on the disordering reaction very precisely. It was found that disorder begins at existing antiphase domain boundaries but that at a slightly higher temperature (1°C) it also occurs by homogeneous nucleation within the domains. A small (∼ .01°C) further increase in temperature caused these micro-domains to completely fill the specimen.

Fundamental Research into Thin Films in a Developing Country

1972 ◽  
Vol 30 ◽  
pp. 500-501
Author(s):  
J.A. Eades ◽  
E. Grünbaum
Keyword(s):  
Thin Films ◽  
Growth Process ◽  
Empirical Process ◽  
Nucleation And Growth ◽  
Research Groups ◽  
Film Research ◽  
Fundamental Research ◽  
Controlled Deposition ◽  
The One ◽  
The University

In the last decade and a half, thin film research, particularly research into problems associated with epitaxy, has developed from a simple empirical process of determining the conditions for epitaxy into a complex analytical and experimental study of the nucleation and growth process on the one hand and a technology of very great importance on the other. During this period the thin films group of the University of Chile has studied the epitaxy of metals on metal and insulating substrates. The development of the group, one of the first research groups in physics to be established in the country, has parallelled the increasing complexity of the field.The elaborate techniques and equipment now needed for research into thin films may be illustrated by considering the plant and facilities of this group as characteristic of a good system for the controlled deposition and study of thin films.

STM studies of crystal growth

1991 ◽  
Vol 49 ◽  
pp. 374-375
Author(s):  
M. G. Lagally
Keyword(s):  
Crystal Growth ◽  
Molecular Beam ◽  
Chemical Vapor ◽  
Sputter Deposition ◽  
Field Of View ◽  
Scanning Tunneling ◽  
Wide Field ◽  
Tunneling Microscopy ◽  
Wide Field Of View ◽  
The One

It has been recognized since the earliest days of crystal growth that kinetic processes of all Kinds control the nature of the growth. As the technology of crystal growth has become ever more refined, with the advent of such atomistic processes as molecular beam epitaxy, chemical vapor deposition, sputter deposition, and plasma enhanced techniques for the creation of “crystals” as little as one or a few atomic layers thick, multilayer structures, and novel materials combinations, the need to understand the mechanisms controlling the growth process is becoming more critical. Unfortunately, available techniques have not lent themselves well to obtaining a truly microscopic picture of such processes. Because of its atomic resolution on the one hand, and the achievable wide field of view on the other (of the order of micrometers) scanning tunneling microscopy (STM) gives us this opportunity. In this talk, we briefly review the types of growth kinetics measurements that can be made using STM. The use of STM for studies of kinetics is one of the more recent applications of what is itself still a very young field.

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