Influence of the wall on the heat transfer process in rotary kiln

Magdeburg, Univ., Fak. für Verfahrens- und Systemtechnik, Diss., 2010

Aspectos interessantes observados na meiose de alguns hemípteros

Particular aspects of the meiosis of two species of Hemiptera, namely Megalotomus pallescens (Stal) (Coriscidae) and Jadera sanguinolenta (Fabr.); (Corizidae) are described and discussed in this paper. Megalotomus pallescens This species has primary spermatocytes provided with 7 autosomal tetrads plus a single sex chromosome. The X is smaller than the autosomes and may be found either in the periphery of the circle formed by the autosomal tetrads or in the center together with the m-tetrad which always occupies this position. The X chromosome - In the primary spermatocytes this element, which is tetradiform, orients itself parallelly to the spindle axis and divides transversely by its median constriction. In the secondary spermatocytes it passes undivided to one pole. The m-chromosomes - These chromosomes have been frequently found in close association with the sex chromosome in nuclei wich have passed the diffuse stage, a fact which was considered as affording some evidence in support of the idea /developed by the present writer in another paper with regard to the origin of the m-chromosomes from the sex chromosome. Formation of tetrads - Tetrads appear at first as irregular areas of reticular structure, becoming later more and more distinct. Then, two chromosomal strands very loose and irregular in outline, connected whit each other by several transverse filaments, begin to develop in each area. Growing progressively shorter, thicker and denser, these strands soon give origin to typical Hemiptera tetrads. Jadera sanguinolenta Spermatogonia of this species have 13 chromosomes, that is, 10 autosomes, 2 m-chromosomes and one sex chromosome, one pair of autosomes being much larger than the rest. Chromosomes move toward the poles with both ends looking to them. Primary spermatocytes show 6 tetrads and a single X. The sex chromossome in the first division of the spermatocytes divides as if it was a tetrad, passing undivided to one pole in the second division. In the latter it does not orient, being found anywhere in the cells. Its most common situation in anaphase corresponds therefore to precession. Tetrads are formed here in an entirely different way : the bivalents as they become distinct in the nuclei which came out. of the diffuse stage they appear in form of two thin threads united only at the extremities, an aspect which may better be analized in the larger bivalent. Up from this stage the formation of the tetrads is a mere process of shortening and thickening of both members of the pair. Due to the fact that the paired chromosomes are well separated from each other throughout their entire lenght, the author concluded that chiasmata, if present, are accumulated at the very ends of the bivalents. If no chiasmata have been at all formed, then, what holds together the corresponding extremities must be a strong attraction developed by the kinetochores. If one interprets the bivalents represented in the figures 17-21 as formed by four chromatids paired by one of the ends and united by the opposite one, then the question of the diffuse attachment becomes entirely disproved since it is exactly by the distal extremities that the tetrads later will be connected with the poles. In the opinion of the present writer the facts referred to above are one of the best demonstration at hand of the continuity of the paired threads and at the same time of the dicentricity of Hemiptera chromosomes. In view of the data hitherto collected by the author the behavior of the sex chromosome of the Hemiptera whose males are of the XO type may be summarized as follows: a) The sex chromosome in the primary metaphase appears longitudinally divided, without transverse constriction. It is oriented with the extremities in the plane of the equator and its chromatids separate by the plane of division. (Euryophthalmus, Protenor). In the second division the sex chromosome, provided as it is with an active kinetochore at each end, orients itself with its lenght parallelly to the spindle axis and passes undivided to one pole (Protenor?), or loses to the other pole a centric end (Euryophthalmus) In the latter case it has to become dicentric by means of a longitudinal spliting beginning at the kinetochore. b) The sex chromosome in the primary metaphase is tetradiform, that is, it is provided with a longitudinal split and a median transverse constriction. Orients with its length paral lelly to the spindle axis (what is probably due to the kinetochores being not yet divided) and divides transversely. (Corizas hyalinus, Megalotomus pallescens). in the secondary metaphase the sex chromosome which turned to be dicentric in consequence of a longitudinal spliting initiated in the kineto chore, orients perpendicularly to the equatorial plane and without losing anyone of its extremities passes undivided to one pole (Megalotomus). Or, distending between both poles passes to one side, in which case it loses one of its ends to the other side. (Corizas hyalinus). c) The very short sex chromosome in the first division of the spermatocytes orients in the same manner aa the tetrads and divides transversely. In the second division, due to the inactivity o the inetochore, it remains monocentric and motionless anywhere in the cell, finishing by being enclosed in the nearer nucleus. In the secondary telophase it recuperates its dicentricity at the same time as the autosomal chromatids. (Jadera sanguinolenta, Diactor bilineatus). d) The sex chromosome in the first division orients in the equador with its longitudinal axis parallelly to the spindle axis passing integrally to one pole or, distending itself between the anaphase plates, loses one of its ends to the opposite pole. In this case it becomes dicentric in the prometaphase of the second division, behaving in this division as the autossomes. It thus divides longitudnally. (Pachylis laticomis, Pachylis pharaonis).

novel reactive distillation process for the production of cyclohexanol from cyclohexene

Magdeburg, Univ., Fak. für Verfahrens- und Systemtechnik, Diss., 2010

Influence of water quality and kind of metal in the secondary cooling zone of casting process

Magdeburg, Univ., Fak. für Verfahrens- und Systemtechnik, Diss., 2012

Collaboration process design for ideation in distributed environments : approaches to support collaborative ideation in global virtual groups using technological support

Magdeburg, Univ., Fak. für Informatik, Diss., 2012

Algorithmic assistance to the optimization process in vehicle routing problems

Magdeburg, Univ., Fak. für Maschinenbau, Diss., 2013

Issues of information support for the process of scientific enterprise's management in the universities and research organizations

This article describes the problem of commercializing of scientific researches in universities. Management tasks are reduced to subtasks and combined formal algorithm. The overall control problem is reduced to a set of formal subtasks combined into a single algorithm. Here the necessity of joint control of all commercialization projects as well as the use of information systems for the successful implementation of the existing commercialpotential is shown.

Electron Beam Welding In-Process Control and Monitoring

This work presents the results of an investigation of processes in the melting zone during Electron Beam Welding(EBW) through analysis of the secondary current in the plasma.The studies show that the spectrum of the secondary emission signal during steel welding has a pronounced periodic component at a frequency of around 15–25 kHz. The signal contains quasi-periodic sharp peaks (impulses). These impulses have stochastically varying amplitude and follow each other inseries, at random intervals between series. The impulses have a considerable current (up to 0.5 A). It was established that during electron-beam welding with the focal spot scanning these impulses follow each other almost periodically. It was shown that the probability of occurrence of these high-frequency perturbation increases with the concentration of energy in the interaction zone. The paper also presents hypotheses for the mechanism of the formation of the high-frequency oscillations in the secondary current signal in the plasma.

Wa(h)re Lust - Sex Toys im Wandel der Zeit : mit besonderem Fokus auf die sexualpädagogische Praxis

[s.c.]

Process design based on CO 2-expanded liquids as solvents

Magdeburg, Univ., Fak. für Verfahrens- und Systemtechnik, Diss., 2014

Evaluation of process concepts for liquid-liquid systems exemplified for the indirect hydration of cyclohexene to cyclohexanol

Magdeburg, Univ., Fak. für Verfahrens- und Systemtechnik, Diss., 2014

Process of fixation, imobilization and mineralization of ammonium in soil using N-15

The organic and inorganic forms of soil nitrogen and how they participate in the process of fixation, immobilization and mineralization of ammonium in soils were evaluated, after different periods of incubaton, utilizing two soils, a Lithic Haplustoll and a Typic Eutrorthox. The results obtained permit to suggest that : 1) The method for determination of the ammonium fixing capacity based on the extraction with 2N KC1, is considered to be subject to interferences of other soil fractions capable of retaining ammonium. 2) The increase in exchangeable ammonium content is related to the decrease in amino acids and hydrolyzable ammonium. 3) The immobilization and mineralization processes are still held under mil microbial. The forms more affected by this condition are amino acids and hydrolyzable ammonium.

Secondary sex characters of Chinese frogs and toads.

v.22:no.2(1936)

Sex ratio and morphological characteristics of rufous gnateaters, Conopophaga lineata (Aves, Passeriformes) in Atlantic forest fragments

Unequal sex ratios lead to the loss of genetic variability, decreasing the viability of populations in the long term. Anthropogenic activities often disturb the natural habitats and can cause alterations in sex ratio and morphological characteristics of several species. Forest fragmentation is a major conservation concern, so that understanding its effects in natural populations is essential. In this study, we evaluated the sex ratio and the morphological characteristics of Rufous Gnateaters (Conopophaga lineata (Wied, 1831)) in small and large forest fragments in Minas Gerais, Brazil. Birds (n = 89) were sexed by plumage characteristics and molecular markers. The molecular analysis showed that plumage is not a totally reliable method for sexing Rufous Gnateaters. We observed that sex ratio did not differ between large and small forest fragments, but birds in small fragments had larger wings and tarsus. Wing and tarsus changes may affect the movement ability of individuals within and among forest fragments. In conclusion, Rufous Gnateaters have been able to survive in both small and large Atlantic rain forest fragments without altering their sex ratio, but morphological changes can be prejudicial to their long term survival.