Search results for "structures"
showing 10 items of 4815 documents
Maternal antibody transmission and breeding densities in the Black-headed Gull Larus ridibundus
2004
1. The offspring of avian species, especially those of colonial breeders, are exposed to a number of pathogens immediately after birth. The chick's immune system is, at that early stage still immature and inefficient. As a consequence, diseases can have a strong impact on chick survival.2. The ability of mothers to transmit passive immunity in terms of antibodies of their own acquired immunity to their chicks is probably an essential pathway to enhance the chick survival. Since the production of antibodies is costly, females are expected to adjust the transmission of passive immunity to the local disease environment.3. We found that in Black-headed Gulls (Larus ridibundus L.) yolk antibody …
Teschoviruses and sapeloviruses in faecal samples from wild boar in Spain
2013
Teschovirus and Sapelovirus are two genera of the Picornaviridae family, comprising highly variable and heterogeneous enteric viruses, commonly found in faecal samples from domestic pigs. Although both of them are also known to infect wild boar, studies on their presence in these wild suids are scarce. The present study aimed at determining the presence of porcine teschovirus (PTV) and sapelovirus (PSV) in free-living wild boar populations, as well as to study their relationships with similar viruses present in pigs. Fresh faecal samples (n = 63) from wild boar were collected in Doñana Biological Reserve (SW Spain) during 2007 and 2011, and analysed using multiplex RT-PCR for the simultaneo…
Transgenerational immunity in a bird-ectoparasite system: do maternally transferred antibodies affect parasite fecundity or the offspring's susceptib…
2009
During egg formation, female birds deposit antibodies against parasites and pathogens they were exposed to before egg laying into the yolk. In captive bird species, it has been shown that these maternal immunoglobulins (maternal yolk IgGs) can protect newly hatched offspring against infection. However, direct evidence for such benefits in wild birds is hitherto lacking. We investigated (1) if nestling Great Tits Parus major originating from eggs with naturally high levels of maternal yolk IgG are less susceptible to a common, nest-based ectoparasite, (2) if maternal yolk IgGs influence nestling development and in particular, their own immune defence, and (3) if there is a negative correlati…
Primo ricerche sulla ultrastruttura dell'uovo delle Ascidie
1959
Summary The cytoplasmic constituents of the unfertilized eggs of Ciona intestinalis were separated by centrifugation and studied at the electron microscope, with the following results. Lipid droplets collect at the centripetal pole; they are boundered by a thin membrane. The yolk granules are homogeneous in appearance; a few have a granular structure. Mitochondria contain numerous cristae; they accumulate in two different layers centripetally and centrifugally to the yolk granules layer respectively. Basophilic material collects at both poles of the egg in two hyaline caps: a centripetal one constituted by small Vesicles and a centrifugal represented by dense clumps. The latter, as well as …
A morphometric comparison of dissimilar early development in sibling species of Platynereis (Annelida, Polychaeta)
1992
Early development of Platynereis massiliensis was studied in serial sections of fixed embryos and in living or fixed embryos whose nuclei had been made visible with a fluorescent label. The unfertilized egg is an ellipsoid with three axes of differing length. The longest axis corresponds to the dorsoventral axis of the developing embryo. Egg volume is ten times that in the sibling species, P. dumerilii, mainly due to increased yolk content. The timing and spatial pattern of cleavage were observed from first cleavage to the 62-cell stage. Volumes of the blastomeres, their nuclei, their yolk-free cytoplasm and their yolk were determined from serial sections up to the 29-cell stage. In the P. …
SOME COMPARATIVE REMARKS ON THE TRANSIENT CHANGE IN LACTIC ACID CONTENT IN SEA URCHIN EGGS FOLLOWING FERTILIZATION.
1964
Abstract During the first few minutes following fertilization a transient increase in the concentration of lactic acid occurs in the eggs of Arbacia lixula , whereas no change at all is observed in the eggs of Paracentrotus liuidus . In the eggs of Psammechinus miliaris there is a transient decrease, soon followed by a recovery so that the level of the unfertilized egg is again reached.
Food colour additives of natural origin
2015
Abstract Colour is an often overlooked sensory character that certainly influences flavour perception. Pigments colouring food are generally unstable and are modified during processing. To maintain or restore product colour uniformity, colouring agents, considered worldwide as food additives, are intentionally added to food products. The natural food additives market has been growing extensively since the last century due to the potential hazards of artificial food additives and the potential benefits of biologically active compounds. In this chapter, a fairly compressed overview of the most important colours of natural origin as well as information about less common or/and promising colour…
Dix ans d'archéologie forestière dans le Châtillonnais (Côte-d'Or) : enclos, habitats, parcellaires
2010
National audience; Ces recherches sur les ensembles de structures de pierre sous forêt sont mises en œuvre depuis dix ans et sont inté- grées depuis 2003 dans le P.C.R. ‘Vix et son Environnement', dirigé par C. Mordant, S. Wirth et B. Chaume. Les vestiges étudiés sont implantés dans deux milieux géographiques distincts mais contigus : le plateau calcaire recouvert par la forêt domaniale de Châtillon, et les rebords de la Digeanne et du Brevon qui entaillent ce plateau à l'est et au sud. La prospection présente ici des caractères particuliers liés au couvert forestier. Les relevés G.P.S. sont intégrés dans un S.I.G. et constituent la base de cette étude, dans un va et vient…
Typologie des enclos dans les forêts du Châtillonnais (Côte d'Or)
2014
Alors que de nombreux parcellaires sous forêts sont révélés par le Lidar et le plus souvent attribués à la période gallo-romaine, les parcellaires du Châtillonnais étudiés à travers les habitats par différents moyens ( relevés GPS, indices Lidar et prospections pédestres) donnent des indices d'une occupation plus ancienne. Ces habitats appréhendés par les structures externes en élévation se répartissent en groupes distincts par la forme de l'enclos qui les entourent, la présence ou non d'une construction en pierres. Pour une partie des enclos de forme quadrangulaire, la spécificité du matériel recueilli oriente vers une fonction cultuelle.
Design and simulation of efficient combinational circuits based on a new XOR structure in QCA technology
2021
AbstractQuantum-dot cellular automata (QCA), due to its unique characteristics like low power consumption, nanoscale design, and high computing speed is considered as an emerging technology, and it can be used as an alternative for CMOS technology in circuit design for quantum computers in the near future. XOR gate has many applications in the design of digital circuits in QCA. In this paper, an efficient novel structure of XOR gate is proposed in QCA. Also, a novel 1-bit comparator circuit, 1-bit full adder, binary to gray and gray to binary convertor code based on the proposed XOR is designed and simulated using QCADesigner 2.0.3. The simulation results demonstrated that the proposed stru…