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29642. The life and work of professor Martin Gavalec (11.11.1942 - 23.3.2021)
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Language:
- English
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
29643. The life cycle of Dichelyne (Cucullanellus) minutus (Nematoda: Cucullanidae)
- Creator:
- Køie, Marianne
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Nematoda, Cucullanidae, Dichelyne (Cucullanellus) minutus, life cycle, flatfish, goby, and Nereis diversicolor
- Language:
- English
- Description:
- Mature specimens of the nematode Dichelyne (Cucullanellus) minutus (Rudolphi, 1819) (Ascaridida, Cucullanidae, Seuratoidea) were obtained from the intestine of flounder Platichthys flesus (L.) caught in the Øresund, Denmark. Plaice Pleuronectes platessa L. and common goby Pomatoschistus microps (Kröyer) also harbour this species. The eggs embryonate on the seabottom. Larvae about 440 µm long, and believed to be in their third stage, hatch from the eggs. These larvae are not directly infective to flounders or gobies. The polychaete Nereis diversicolor O.F. Müller acts as obligatory intermediate host. Experimental infections showed that larvae >600 µm long and provided with a chitinous tooth survived in flounder and common goby. The third-stage larvae moult to fourth-stage larvae in the fish gut wall. Mature worms occur in the lumen of the anterior part of the intestine. All developmental stages may be transferred from one flounder to another; thus the flounder may acquire the parasite also by devouring infected gobies.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
29644. The life cycle of Haemogregarina bigemina (Adeleina: Haemogregarinidae) in South African hosts
- Creator:
- Davies, Angela J. and Smit, Nico J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Adeleina, Haemogregarinidae, Haemogregarina bigemina, Gnathia africana, fish parasites, blood parasites, transmission, and life cycle
- Language:
- English
- Description:
- Haemogregarina bigemina Laveran et Mesnil, 1901 was examined in marine fishes and the gnathiid isopod, Gnathia africana Barnard, 1914 in South Africa. Its development in fishes was similar to that described previously for this species. Gnathiids taken from fishes with H. bigemina, and prepared sequentially over 28 days post feeding (d.p.f.), contained stages of syzygy, immature and mature oocysts, sporozoites and merozoites of at least three types. Sporozoites, often five in number, formed from each oocyst from 9 d.p.f. First-generation merozoites appeared in small numbers at 11 d.p.f., arising from small, rounded meronts. Mature, second-generation merozoites appeared in large clusters within gut tissue at 18 d.p.f. They were presumed to arise from fan-shaped meronts, first observed at 11 d.p.f. Third-generation merozoites were the shortest, and resulted from binary fission of meronts, derived from second-generation merozoites. Gnathiids taken from sponges within rock pools contained only gamonts and immature oocysts. It is concluded that the development of H. bigemina in its arthropod host illustrates an affinity with Hemolivia and one species of Hepatozoon. However, the absence of sporokinetes and sporocysts also distances it from these genera, and from Karyolysus. Furthermore, H. bigemina produces fewer sporozoites than Cyrilia and Desseria, although, as in Desseria, Haemogregarina (sensu stricto) and Babesiosoma, post-sporogonic production of merozoites occurs in the invertebrate host. The presence of intraerythrocytic binary fission in its fish host means that H. bigemina is not a Desseria. Overall it most closely resembles Haemogregarina (sensu stricto) in its development, although the match is not exact.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
29645. The life cycle of Myxobolus lentisuturalis (Myxozoa: Myxobolidae), from goldfish (Carassius auratus auratus), involves a Raabeia-type actinospore
- Creator:
- Caffara, Monica, Raimondi, Elena, Florio, Daniela, Marcer, Federica, Quaglio, Francesco, and Fioravanti, Maria Letizia
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Myxosporea, Myxobolus lentisuturalis, actinospore, Raabeia-type, life cycle, Carassius auratus auratus, Branchiura sowerbyi, and Italy
- Language:
- English
- Description:
- We studied a natural infection of the oligochaete Branchiura sowerbyi Beddard, 1892 with the Raabeia-type actinosporean stage of Myxobolus lentisuturalis Dyková, Fiala et Nie, 2002 which infected goldfish Carassius auratus auratus (L.) in Italy, using molecular analysis of the SSU rRNA gene. The existence of intraoligochaete development shows that this parasite follows the life-cycle pattern described by Wolf and Markiw (1984) for Myxobolus cerebralis. Histological examinations of the goldfish infected by M. lentisuturalis showed at low magnification the presence of two bilateral crescent-shaped masses in the dorsal epaxial muscle. These lesions were not circumscribed, presented irregular edges and infiltrated the underlying bundles of skeletal muscle and interstitial tissue. At higher magnification, disappearance of muscle fibres and substitution of the muscle tissue with Myxobolus spores and plasmodia were observed.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
29646. The life cycle of Paracardicoloides yamagutii Martin, 1974 (Digenea: Sanguinicolidae)
- Creator:
- Nolan, Matthew J. and Cribb, Thomas H.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Paracardicoloides yamagutii, Sanguinicolidae, Anguilla reinhardtii, Anguillidae, Posticobia brazieri, Hydrobiidae, and ITS2 rDNA
- Language:
- English
- Description:
- The sanguinicolids Paracardicoloides yamagutii Martin, 1974 and Plethorchis acanthus Martin, 1975 were obtained from their definitive hosts, Anguilla reinhardtii Steindachner and Mugil cephalus Linnaeus (respectively) in the tributaries of the Brisbane River, Queensland, Australia. Two putative sanguinicolid cercariae were collected from a hydrobiid gastropod, Posticobia brazieri Smith, in the same waters. The two cercariae differ markedly in size and the form of their sporocysts. Both putative cercariae develop in the digestive gland of Po. brazieri. The ITS2 rDNA region from these sanguinicolids and a Clinostomum species (utilised as an outgroup due to the close morphological similarities between the cercarial stages of the Clinostomidae and the Sanguinicolidae) were sequenced and aligned. Comparison of the ITS2 sequences showed one cercaria to be that of P. yamagutii. This is the first sanguinicolid life history determined by a molecular method. P. yamagutii is the fourth sanguinicolid known to utilise a freshwater hydrobiid gastropod as its intermediate host. ITS2 rDNA is effective in distinguishing sanguinicolids at the species level.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
29647. The light-dependent and light-independent reduction of protochlorophyllide a to chlorophyllide a
- Creator:
- Schoefs, B.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- bacteriochlorophyll, bacteriochlorophyllide, cysteine, chlorophyll, greening, lysine, methionine, valine, and tyrosine
- Language:
- Multiple languages
- Description:
- Two different pathways for protochlorophyllide a (Pchlide) reduction in photosynthetic organisms have been proved: one is strictly light-dependent whereas the second is light-independent. Both pathways occur in all photosynthetic cells except in angiosperms which form chlorophyll only through the light-dependent pathway. Most cells belonging to Eubacteria (i.e., the anoxygenic photosynthetic bacteria) synthesize bacteriochlorophyll through the light-independent pathway. This review deals with the physiological, biochemical, and molecular biological features of molecules involved in both pathways of Pchlide reduction.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
29648. The Limit Deposit Velocity model, a new approach
- Creator:
- Miedema, Sape A. and Ramsdell, Robert C.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- critical velocity, Limit Deposit Velocity, slurry transport, and Newtonian fluid
- Language:
- Slovak
- Description:
- In slurry transport of settling slurries in Newtonian fluids, it is often stated that one should apply a line speed above a critical velocity, because blow this critical velocity there is the danger of plugging the line. There are many definitions and names for this critical velocity. It is referred to as the velocity where a bed starts sliding or the velocity above which there is no stationary bed or sliding bed. Others use the velocity where the hydraulic gradient is at a minimum, because of the minimum energy consumption. Most models from literature are one term one equation models, based on the idea that the critical velocity can be explained that way. Here the following definition is used: The critical velocity is the line speed below which there may be either a stationary bed or a sliding bed, depending on the particle diameter and the pipe diameter, but above which no bed (stationary or sliding) exists, the Limit Deposit Velocity (LDV). The way of determining the LDV depends on the particle size, where 5 regions are distinguished. These regions for sand and gravel are roughly; very small particles up to 0.014-0.040 mm (d < δv), small particles from δv-0.2 mm, medium particles in a transition region from 0.2-2.00 mm, large particles > 2 mm and very large particles > 0.015·Dp. The lower limit of the LDV is the transition between a sliding bed and heterogeneous transport. The new model is partly based on physics and correlates well with experiments from literature.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
29649. The limits of legitimation: preconditions for conflict resolution by majority rule in the European Union
- Creator:
- Vobruba, Georg
- Format:
- Type:
- model:internalpart and TEXT
- Subject:
- European integration, European Constitution, majority rule, European identity, and legitimation problems
- Language:
- Czech
- Description:
- Expanding the domain of majority rule is widely seen as desirable for the European Union. But the functioning of majority rule depends on preconditions that are seldom taken into account. The basic precondition is that overruled minorities accept majority decisions instead of exiting the voting unit. The specific problem of applying majority rule in the European Union is that overruled minorities at the European level are majorities at the nation-state level. By distinguishing between three dimensions of conflicts - content, time and space - the article analyses under what conditions it is possible to expect minorities to accept majority decisions, thus enabling the resolution of conflict by majority rule at the European level.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
29650. The limits of the beam sag under influence of static magnetic and electric force
- Creator:
- Stein, George Juraj, Darula, Radoslav, and Chmúrny, Rudolf
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- clamped beam sag, electromagnetic actuator, sag approximation, thresh-old current, sag limit, and electrostatic case
- Language:
- English
- Description:
- Utilization of a magnetic force can be found in many mechatronic applications, where e.g. a slender beam or plate is subjected to static magnetic force generated by an electromagnetic actuator consisting of a solenoid wound on a ferromagnetic core and a ferromagnetic armature, fixed to the beam. The static magnetic force, acting perpendicularly onto the beam, causes sag (downwards bending) of the beam. If the magnitude of the magnetic force surpasses some threshold value the armature and hence the beam is completely attracted to the core of the solenoid. For small detections the mathematical expression of the magnetic force can be linearised and approximated by a polynomial dependence on the distance to the electromagnet. In practical application, it is important to analyse the nature of the sag and to determine the limits of the linear approxmation, as well as the limits leading to the full attraction to the electromagnet. The mathematical generalisation of the sag is valid for electrostatic force between planar electrodes, too. and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public