This paper considers an exponential cost optimality problem for finite horizon semi-Markov decision processes (SMDPs). The objective is to calculate an optimal policy with minimal exponential costs over the full set of policies in a finite horizon. First, under the standard regular and compact-continuity conditions, we establish the optimality equation, prove that the value function is the unique solution of the optimality equation and the existence of an optimal policy by using the minimum nonnegative solution approach. Second, we establish a new value iteration algorithm to calculate both the value function and the ϵ-optimal policy. Finally, we give a computable machine maintenance system to illustrate the convergence of the algorithm.
The host immune response to parasitic infections plays an important role in controlling multiplication of the parasite and reducing clinical symptoms and life-threatening complications. Nitric oxide (NO), an important innate immune factor and classic Th1 immune effector, may play a role in inhibiting plasmodium infection. In this study, we used two different approaches (L-Arginine [precursor of NO] and NOC5 [short-time NO donor]) to prove the roles of NO in malaria infection. We used 6-8 week-old female BALB/c mice infected with the rodent malaria Plasmodium yoelii Landau, Michel et Adam, 1968 - strain 17XL (P.y17XL) - as a model. For L-Arg treatment, mice were administered with an oral dose of 1.5 mg/g L-Arg daily for seven consecutive days prior to infection with P.y17XL. L-Arg pretreatment resulted in the decrease of the mRNA level of the apical membrane antigen 1 (AMA1) gene, which encodes a protein involved in host invasion. For NOC5 treatment, NOC5 was injected intraperitoneally into the P.y17XL infected mice on day 5 post-infection or incubated in vitro with purified P.y17XL schizonts. Both in vivo and in vitro treatments with NOC5 led to down-regulation of the transcript and protein levels of invasion-related molecules (AMA1, merozoites surface protein 1 and Py235). Our results confirmed the protective role of NO in the asexual blood stage of parasitic infection, which may be partially due to reduced expression of parasite invasion molecules.
Two new species of feather mites are described from nightjars (Caprimulgiformes: Caprimulgidae) of Brazil: Hartingiella neotropica sp. n. (Xolalgidae) described from Hydropsalis parvula (Gould) and Paragabucinia brasiliensis sp. n. (Gabuciniidae) from H. albicollis (Gmelin). The former differs from the type species by having, in males, the anterior projections on epimerites III towards setae 3b and the adanal shield bearing setae ps3 present; in both sexes, a pair of small sclerites situated posterior to setae se have flat suprategumental processes. Paragabucinia brasiliensis sp. n. differs from P. petitoti (Gaud et Mouchet, 1959) by the smaller size of the incisions in the internal margins of opisthosomal lobes of males. These mites are the first representatives of corresponding genera described from the Neotropical region. The genus Hartingiella Gaud, 1980 was previously known solely from its type species. Keys to males and females of the genus Paragabucinia Gaud et Atyeo, 1975 are presented. In addition, all previous records of feather mites associated with birds of the order Caprimulgiformes of the world are summarised.
Soricimyxum fegati gen. et sp. n. is a new myxosporean (Myxozoa) species discovered in the liver of shrews, Sorex araneus L., collected in the Bialowieza primeval forest (Poland). Both developmental stages and mature spores were found during a histological study. The infection had about 40% prevalence at the investigated locality. Plasmodia were polysporic. Elongated plasmodia with an average size of 30 by 8 µm occupied bile ducts and larger rounded plasmodia up to 80 µm in diameter were found in liver parenchyma where they most probably entered after the ducts had been destructed. Plasmodia in both locations elicited a vigorous inflammatory reaction. Spores were of an ovoid shape, 7 µm long, 5.4 µm wide and about 3.5 µm thick. They had two shell valves and two equal polar capsules, located in opposite ends of the spore.
Toxoplasma gondii Nicolle et Manceaux, 1908 is an apicomplexan parasite with a worldwide distribution. It is of great medical and veterinary importance because it may cause abortion or congenital disease in its intermediate hosts, including man. The European bison, the largest herbivorous animal in Europe, is a species that has been saved from extinction. Twenty-four of 95 examined sera of the European bison (Bison bonasus bonasus) from the Białowieża Forest, Poland collected from 2008 to 2011 were found to be positive for the presence of T. gondii-specific IgG antibodies using a direct agglutination test, with the antibody titre in positive animals ranging from 40 to 18000. Statistically significant differences were observed only between years of sample collection. This is the first report on T. gondii in lowland European bison living in the natural environment.
The phylum Microsporidia is a large group of parasitic unicellular eukaryotes that infect a wide range of invertebrate and vertebrate taxa. These organisms are significant human and veterinary pathogens with impacts on medicine, agriculture and aquaculture. Scientists working on these pathogens represent diverse disciplines that have had limited opportunities for detailed interactions. A NATO Advanced Research Workshop 'Emergent Pathogens in the 21st Century: First United Workshop on Microsporidia from Invertebrate and Vertebrate Hosts' was held July 12-15, 2004 at the Institute of Parasitology of the Academy of Sciences of the Czech Republic to bring together experts in insect, fish, veterinary and human microsporidiosis for the exchange of information on these pathogens. At this meeting, discussions were held on issues related to taxonomy and phylogeny. It was recognized that microsporidia are related to fungi, but the strong opinion of the participants was that the International Code of Zoological Nomenclature should continue to be applied for taxonomic descriptions of the Microsporidia and that they be treated as an independent group emerging from a paraphyletic fungi. There continues to be exponential growth in the pace and volume of research on these ubiquitous intracellular protists. The small genomes of these organisms and the reduction in the size of many of their genes are of interest to many disciplines. Many microsporidia are dimorphic and the mechanisms underlying these morphologic changes remain to be elucidated. Epidemiologic studies to clarify the source of human microsporidiosis and ecologic studies to understand the multifaceted relationship of the Microsporidia and their hosts are important avenues of investigation. Studies on the Microsporidia should prove useful to many fields of biologic investigation.
Chaos is present in many aspect of life. It is very difficult to detect and control chaotic behavior in nonlinear engineering dynamical systems. This contribution deals about some devices for generation of chaotic signals, for example about Chua's circuit, chaos module and analog chaotic oscillators. and Obsahuje seznam literatury
Four new species of the genus Hatschekia Poche, 1902 (Copepoda: Siphonostomatoida: Hatschekiidae) are described based on female specimens collected from pufferfishes (Tetraodontiformes: Tetraodontidae) caught in coastal waters off the Ryukyu Islands, Japan: H. longiabdominalis sp. n. on Arothron hispidus (Linnaeus), H. geniculata sp. n. on A. hispidus (type host) and A. stellatus (Bloch et Schneider), H. ellipsocorpa sp. n. on A. mappa (Lesson), and H. boonah sp. n. on A. nigropunctatus (Bloch et Schneider) (type host) and A. meleagris (Schneider). Hatschekia longiabdominalis sp. n. and H. boonah sp. n. differ from all other congeners by sharing an unusual, projected abdomen and a fusiform trunk with posterior lobes; these two species are differentiated from each other by the shape of the dorsal chitinous frame on the cephalothorax. Hatschekia geniculata sp. n. can be distinguished by the combination of the following morphological characters: a rhomboidal cephalothorax with a pair of lateral conical protrusions, a cylindrical trunk with posterior lobes and a bent abdomen with a dorsal protrusion. Hatschekia ellipsocorpa sp. n. resembles H. pholas (Wilson, 1906) but can be distinguished from the latter by the possession of one distal and one inner setae on the terminal endopodal segment of legs 1 and 2. Hatschekia pholas is also redescribed based on female specimens from the tetraodontid A. stellatus. At present, 44 nominal species of the genus have been reported from Japan, including four new species described in this paper; 38 of them have been described originally from Japan.
In respect of its morphology, biology and epidemiology, Hyalomma (Euhyalomma) impressum Koch, 1844 is one of the more poorly studied ticks of the genus Hyalomma Koch, 1844. No comprehensive morphological study has been done to date, and the nymph has not been described. Here the adults and larva are redescribed, and the nymph is described for the first time. Data on hosts, geographical distribution and disease relationships are provided.