Search results for " forma"
showing 10 items of 3304 documents
The effect of low frequency noise on the behaviour of juvenile Sparus aurata.
2020
[EN] Anthropogenic activities are causing increased noise levels in the marine environment. To date, few studies have been undertaken to investigate the effects of different noise frequencies on the behaviour of juvenile fish. In this study, the behavioural changes of juvenile gilthead seabream (Sparus aurata) are evaluated when exposed to white noise filtered in third-octave bands centred at 63, 125, 500, and 1000 Hz (sound pressure level, 140-150 dB re 1 mu& x3a1;a) for 7 h. The group dispersion, motility, and swimming height of the fish were analysed before and during the acoustic emission. Dispersion of the fish was found to reduce immediately upon application of low frequency sound (63…
Free Radicals Mediate Systemic Acquired Resistance
2014
Summary: Systemic acquired resistance (SAR) is a form of resistance that protects plants against a broad spectrum of secondary infections. However, exploiting SAR for the protection of agriculturally important plants warrants a thorough investigation of the mutual interrelationships among the various signals that mediate SAR. Here, we show that nitric oxide (NO) and reactive oxygen species (ROS) serve as inducers of SAR in a concentration-dependent manner. Thus, genetic mutations that either inhibit NO/ROS production or increase NO accumulation (e.g., a mutation in S-nitrosoglutathione reductase [GSNOR]) abrogate SAR. Different ROS function additively to generate the fatty-acid-derived azel…
Influence of female moulting status on pairing decisions and size‐assortative mating in amphipods
2012
8 pages; International audience; Precopulatory mate guarding is a common strategy, which has evolved in species where the female receptivity (and thus egg fertilization) is predictable, but also limited to a short period. Although males are larger than females in many amphipods, the largest males pair with the largest females, leading to a positive sizeassortative pairing. Size-assortative pairing has received much attention but how moulting physiology could affect pairing decisions has rarely been studied. Here, we tested the hypothesis that the size-assortative pairing in the freshwater amphipod Gammarus pulex is closely related to the female moult cycle. We characterized moulting status …
Direct exposure to solar radiation causes radial growth eccentricity at the beginning of the growing season in Robinia pseudoacacia
2020
Abstract Our study investigated the effect of stem temperature increase on xylem formation in Robinia pseudoacacia tree-trunks, caused by direct exposure to solar radiation. It is important to determine factors which may improve the concentricity of deposited wood tissue and intensify xylogenesis because a strong irregularity of wood tissue deposited in the radial direction in mature trees of R. pseudoacacia reduces the commercial value of the wood. Samples of vascular cambium along with adjacent tissues were collected from the southern (illuminated) and northern (shaded) side of tree-trunks growing in the inner and peripheral (thus exposed to direct sunlight) zones of the research plot. Sa…
Water temperature, not fish morph, determines parasite infections of sympatric Icelandic threespine sticklebacks (Gasterosteus aculeatus)
2013
Parasite communities of fishes are known to respond directly to the abiotic environment of the host, for example, to water quality and water temperature. Biotic factors are also important as they affect the exposure profile through heterogeneities in parasite distribution in the environment. Parasites in a particular environment may pose a strong selection on fish. For example, ecological differences in selection by parasites have been hypothesized to facilitate evolutionary differentiation of freshwater fish morphs specializing on different food types. However, as parasites may also respond directly to abiotic environment the parasite risk does not depend only on biotic features of the hos…
Assortative mating by size without a size-based preference: the female-sooner norm as a mate-guarding criterion.
2013
7 pages; International audience; The study of size-assortative mating, or homogamy, is of great importance in speciation and sexual selection. However, the proximate mechanisms that lead to such patterns are poorly understood. Homogamy is often thought to come from a directional preference for larger mates. However, many constraints affect mating preferences and understanding the causes of size assortment requires a precise evaluation of the pair formation mechanism. Mate-guarding crustaceans are a model group for the study of homogamy. Males guard females until moult and reproduction. They are also unable to hold a female during their own moult and tend to pair with females closer to moult…
Giant, unconventional anomalous Hall effect in the metallic frustrated magnet candidate, KV 3 Sb 5
2020
The anomalous Hall effect soars when Dirac quasiparticles meet frustrated magnetism.
Single point incremental forming: An assessment of the progress and technology trends from 2005 to 2015
2017
The last decade has seen considerable interest in flexible forming processes. Among the upcoming flexible forming techniques, one that has captured a lot of interest is single point incremental forming (SPIF), where a flat sheet is incrementally deformed into a desired shape by the action of a tool that follows a defined toolpath conforming to the final part geometry. Research on SPIF in the last ten years has focused on defining the limits of this process, understanding the deformation mechanics and material behaviour and extending the process limits using various strategies. This paper captures the developments that have taken place over the last decade in academia and industry to highlig…
State effects and the effects of state building: institution building and the formation of state-centred societies
2016
AbstractThis article discusses the assumptions underlying state-building efforts and the effects of these efforts. It addresses two main questions: why has state building not led to the establishment of effective states? And what are the effects of statebuilding? It is argued that these efforts have been based on an institutionalist model of the state derived from a Weberian framework, and that the basic reason why state building has failed is that the creation of effective states requires the creation of state-centred societies, where both material and symbolic resources are concentrated in the state. This is very difficult to achieve for external actors. But, although state building has n…
Positive Controls in Adults and Children Support That Very Few, If Any, New Neurons Are Born in the Adult Human Hippocampus.
2020
Adult hippocampal neurogenesis was originally discovered in rodents. Subsequent studies identified the adult neural stem cells and found important links between adult neurogenesis and plasticity, behavior, and disease. However, whether new neurons are produced in the human dentate gyrus (DG) during healthy aging is still debated. We and others readily observe proliferating neural progenitors in the infant hippocampus near immature cells expressing doublecortin (DCX), but the number of such cells decreases in children and few, if any, are present in adults. Recent investigations using dual antigen retrieval find many cells stained by DCX antibodies in adult human DG. This has been interprete…