Number of results to display per page
Search Results
67672. The discovery of male Caligus brevicaudatus Scott, 1901 (Copepoda: Caligidae) parasitic on tub gurnard, Chelidonichthys lucerna (Linnaeus) from the eastern Mediterranean
- Creator:
- Demirkale, İbrahim, Özak, Argun Akif, and Geoffrey Allan Boxshall
- Format:
- electronic, počítač, and online zdroj
- Type:
- model:article and TEXT
- Subject:
- korýši, mořské ryby, Crustacea, marine fishes, ectoparasite, redescription, Mediterranean Sea, 2, and 59
- Language:
- English
- Description:
- Caligus brevicaudatus Scott, 1901, a common but poorly known species of parasitic copepod, is redescribed from newly collected specimens of both sexes. The new material was collected from the body surface of tub gurnards, Chelidonichthys lucerna (Linnaeus), caught in eastern Mediterranean waters off the Turkish coast. Inadequately described female structures from earlier descriptions are redescribed and illustrated in detail and the male of C. brevicaudatus is described for the first time. The new material of C. brevicaudatus is compared with material collected by A. Scott and stored in the collections of the Natural History Museum, London. In addition, a voucher specimen of Caligus uranoscopi Vaissière, 1955, stored in the collections of the Muséum National d'Histoire Naturelle in Paris is re-examined. Caligus uranoscopi is recognised as a junior subjective synonym of C. brevicaudatus since it does not differ in any substantive characters., İbrahim Demirkale, Argun Akif Özak, Geoffrey Allan Boxshall., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
67673. The dispersal ability of wood cricket (Nemobius sylvestris) (Orthoptera: Gryllidae) in a wooded landscape
- Creator:
- Brouwers, Niels C., Newton, Adrian C., and Bailey, Sallie
- Type:
- article, články, model:article, and TEXT
- Subject:
- Zoologie, entomologie, Gryllidae, Nemobius sylvestris, dispersal ability, woodland, forest, population spread, landscape, habitat network, 2, and 59
- Language:
- English
- Description:
- Information on the dispersal ability of flightless insect species associated with woodlands is severely lacking. Therefore, a study was conducted examining the dispersal ability of wood cricket (Nemobius sylvestris) juveniles (nymphs) and adults in a wooded landscape on the Isle of Wight, UK, to further our understanding of the ecology and management of this and other flightless insects. A series of experiments were conducted where nymphs and adults were released and observed at a range of spatial-temporal scales within different habitat environments. The results of this investigation indicated no difference in the dispersal ability of wood cricket nymphs and adults. However, adult females moved less than adult males. Adult males were found to spread twice as fast as females, and males were found capable of traversing up to 55 m away from woodland habitat through semi-natural and grazed grassland. Additionally, rates of population spread of both wood cricket nymphs and adults (males and females) were found to be accurately described by the inverse-power function, predicting only few individuals dispersing over time. Together this indicates that overall colonization success and rate of population spread, being female dependent, is likely to be low for this species. Wood crickets were found to live in and able to move along mature woodland edges directly bordering agricultural land. This indicates that conservation initiatives focusing on creating woodland corridors and developing woodland habitat networks have the potential to facilitate the spread and population viability of wood crickets, if the woodland edges are given enough time to develop. However, long-term monitoring is needed to evaluate the overall effectiveness of such approaches. and Niels C. BROUWERS, Adrian C. NEWTON, Sallie BAILEY.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
67674. The dispersal of meteoroid streams by radiative effects
- Creator:
- Olsson-Steel, Duncan
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- meteor astronomy, meteoroid streams, and stream dispersion
- Language:
- Czech
- Description:
- A major problém in meteor astronomy is why the orbits of meteoroids within particular streams are so dispersed. For streams with aphelia well within Jupiter (such as the Geminids) planetary perturbations cause insignificant dispersion but can accommodate the required motion of the nodal heliocentric distance to explain why the Geminids were not observed prior to the 1860's. The spread in the orbits wouid also require unreasonably large ejection velocities from the parent. Another dispersal mechanism is therefore required. By incorporating perturbations due to the Yarkovsky-Radzievskii effect into the model the Geminid dispersal can be understood; by including also the effects of the radiation pressure and Poynting- Robertson forces the main observed characteristics of the stream (shower duration variation with magnitude; skew rate profile; changes in mass distribution and radiant diffuseness as the shower progresses) are explicable. The necessary spin rates (about 3000 rev/sec for 1 mm and 1000 rev/sec for 1 cm radius meteoroids) wouid be attained within a thousand years of release from the parent body, due to spin-up under solar radiation pressure. It therefore appears that the Yarkovsky- Radzievskii effect is an important source of stream dispersion which has been hitherto neglected, but should be included in future models.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
67675. The dissident and the spectre: reading Havel with Derrida
- Creator:
- Björk, Ulrika
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Havel, Derrida, dissident, spectre, ideology, post-democracy, and messianism
- Language:
- Czech
- Description:
- In this paper I argue that there is an affinity between the ‘dissident’ in Havel’s essay “The Power of the Powerless” and the ‘spectre’ in Derrida’s readings of Marx. Both are manifestations of a specific modern temporality that Derrida calls “disjointed”, because it is haunted by a revolutionary force and claim for justice. Both also evoke the weak messianic power inherent in Walter Benjamin’s historiography and the spectral responsibility recognised by this power, that is, our responsibility for past and future generations. In post-totalitarian Czechoslovakia, the “nonpolitical” dissident community prefigured the renewal of moral experiences of responsibility and solidarity. In contemporary discussions of democracy, the figure of the spectre is a reminder of the significance of the Marxist legacy beyond its ideological doctrine.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
67676. The distance between fixed points of some pairs of maps in Banach spaces and applications to differential systems
- Creator:
- Mortici, Cristinel
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- contraction principle and Cauchy problem
- Language:
- English
- Description:
- Let $T$ be a $\gamma $-contraction on a Banach space $Y$ and let $S$ be an almost $\gamma $-contraction, i.e. sum of an $\left( \varepsilon ,\gamma \right) $-contraction with a continuous, bounded function which is less than $\varepsilon $ in norm. According to the contraction principle, there is a unique element $u$ in $Y$ for which $u=Tu.$ If moreover there exists $v$ in $Y$ with $v=Sv$, then we will give estimates for $\Vert u-v\Vert .$ Finally, we establish some inequalities related to the Cauchy problem.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
67677. The distinctive pattern of photosystem 2 activity, photosynthetic pigment accumulation, and ribulose-1,5-bisphosphate carboxylase/oxygenase content of chloroplasts along the axis of primary wheat leaf lamina
- Creator:
- Dilnawaz, F., Mohapatra, P., Misra, M., Ramaswamy, N. K., and Misra, A. N.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carotenoids, chlorophyll, CO2 fication ability, photosystem 2, protein, thylakoid, and Triticum aestivum
- Language:
- Multiple languages
- Description:
- Wheat (Triticum aestivum L. cv. Sonalika) seedlings were grown in Hoagland solution. Primary leaves were harvested at 8, 12, and 15 d and cut into five equal segments. Contents of photosynthetic pigments and proteins, and photosystem 2 (PS2) activity increased from base to apex of these leaves. Chlorophyll (Chl) content was maximum at 12 d in all the leaf segments, but PS2 activity showed a gradual decline from 8 to 15 d in all leaf segments. In sharp contrast, the CO2 fixation ability of chloroplasts increased from 8 to 15 d. CO2 fixation ability of chloroplasts started to decline from base to apex of 15-d-old seedlings, where the content of ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (RuBPCO-LSU) increased acropetally. RuBPCO-LSU content was maximum in all the leaf segments in 12-d-old seedlings. This shows a distinctive pattern of PS2, Chl, CO2 fixation ability of chloroplasts, and RuBPCO-LSU content along the axis of leaf lamina during development and senescence. RuBPCO-LSU (54 kDa) degraded to fragments of 45, 42, 37, 19, and 16 kDa products which accumulated along the leaf axis during ageing of chloroplasts. Thus the CO2 fixation ability of chloroplasts declines earlier than PS2 activity and photosynthetic pigment contents along the leaf lamina. and F. Dilnawaz ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
67678. The distinctive rationality of intentions
- Creator:
- Botting, David
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Broome, cognitivism, krasia, and practical rationality
- Language:
- Slovak
- Description:
- In this paper I intend to defend Broome’s cognitivist view that reduces practical normativity to theoretical normativity, but argue that this leaves unaccounted for distinctively practical norms that I seek to capture as a system of local obligations to have particular intentions. The krasia requirement dictates what obligations we have relative to the normative beliefs that we have but does not tell us what intentions it is rational to have all-things-considered., V této práci zamýšlím obhájit Broomeův kognitivistický pohled, který redukuje praktickou normativnost na teoretickou normativitu, ale argumentuje tím, že tyto listy nezohledňují výrazně praktické normy, které se snažím zachytit jako systém místních povinností, které mají konkrétní záměry. Požadavek krasia diktuje, jaké povinnosti máme ve vztahu k normativním názorům, které máme, ale neříká nám, jaké úmysly je racionální mít všechny věci., and David Botting
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
67679. The distribution and abundance of the nematode Anguillicola australiensis in eels Anguilla reinhardtii in Queensland, Australia
- Creator:
- Kennedy, C.R.
- Format:
- Type:
- model:internalpart and TEXT
- Subject:
- Anguillicola australiensis, Anguilla reinhardtii, ecology, distribution, population biology, transmission, pathology, and Australia
- Language:
- English
- Description:
- Anguillicola australiensis (Johnston et Mawson, 1940) is widespread and common in Anguilla reinhardtii Steidachner in rivers and dams of eastern Queensland, Australia, having been found in nine out of ten localities. Overall prevalence was 50% and maximum local prevalence reached 77.7%. The parasite never attained high levels of abundance and maximum adult abundance never exceeded 3.22 or intensity 10. Adults were overdispersed throughout the eel populations and abundance was unrelated to eel or swimbladder size. The greater part of the adult population was composed of immature parasites. The occurrence of larvae in the swimbladder wall was erratic and unrelated to the size of the adult population. Larvae were never abundant and the great majority were damaged by a host response. It appears that parasites either pass through the swimbladder wall rapidly and moult to adults or if delayed are destroyed. There was no indication that a paratenic host was involved in the life cycle. There was no evidence that adult parasites had any local pathogenic effects on their hosts. The population biology of Anguillicola australiensis in its natural host Anguilla reinhardtii appears to be far more similar to those of other Pacific species of Anguillicola in Anguilla japonica in China and Japan than to A. crassus in Anguilla anguilla in Europe or Japan. This latter host-parasite combination appears to be the exception not the rule. It is suggested that the lack of pathogenicity of A. australiensis may reflect a long period of host-parasite co-evolution and/or lower transmission rates resulting in lower parasite population densities.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
67680. The distribution and genetic diversity of the common hamster Cricetus cricetus in Central and Western Romania
- Creator:
- Hegyeli, Zsolt, Kecskés, Attila, Korbut, Zofia, and Banaszek, Agata
- Type:
- article, model:article, and TEXT
- Subject:
- conservation, endangered species, mtDNA, phylogeography, and species range
- Language:
- English
- Description:
- The existing literature, museum records, personal reports of field biologists and our own field results were compiled to assess the present distribution of the common hamster within Transylvania and the Pannonian Plain of Romania. Combining available distribution data and the existence of natural barriers we were able to designate five, possibly separate, populations: the Pannonian Plain, the Transylvanian Plateau, the Olt Valley, the Braşov Depression and the Ciuc Depression population. The Pannonian Plain and the Transylvanian Plateau populations showed mass outbreaks in recent years. Twenty three individuals were available for the genetic analyses. The populations belonged to the Pannonia lineage, based on the sequences of 16SrRNA, cytb and ctr of mtDNA. In general we found very high diversity in mtDNA and 16 microsatellite loci. Moreover the most common ctr haplotypes for the Transylvanian Plateau were also present in the Pannonian Plain population and in populations from Hungary and Slovakia, which indicates recent or even current exchange of individuals. Summing up, recent mass outbreaks and high levels of genetic diversity, with some indication of current or very recent gene flow, showed that Romanian populations are in good state, at least compared to many other European countries. As such, these populations should be of particular interest and placed under protection, as they could serve as the reservoir of the genetic variability for the European Pannonia lineage of the common hamster.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public