1,239 research outputs found
Effect of Grazing-Mediated Dimethyl Sulfide (DMS) Production on the Swimming Behavior of the Copepod Calanus helgolandicus
Chemical interactions play a fundamental role in the ecology of marine foodwebs. Dimethyl sulfide (DMS) is a ubiquitous marine trace gas that acts as a bioactive compound by eliciting foraging behavior in a range of marine taxa including the copepod Temora longicornis. Production of DMS can rapidly increase following microzooplankton grazing on phytoplankton. Here, we investigated whether grazing-induced DMS elicits an increase in foraging behavior in the copepod Calanus helgolandicus. We developed a semi-Automated method to quantify the effect of grazing-mediated DMS on the proportion of the time budget tethered females allocate towards slow swimming, typically associated with feeding. The pooled data showed no differences in the proportion of the 25 min time budget allocated towards slow swimming between high (23.6 ± 9.74%) and low (29.1 ± 18.33%) DMS treatments. However, there was a high degree of variability between behavioral responses of individual copepods. We discuss the need for more detailed species-specific studies of individual level responses of copepods to chemical signals at different spatial scales to improve our understanding of chemical interactions between copepods and their prey. © 1996-2013 MDPI AG
On the self-similarity of line segments in decaying homogeneous isotropic turbulence
The self-similarity of a passive scalar in homogeneous isotropic decaying
turbulence is investigated by the method of line segments (M. Gauding et al.,
Physics of Fluids 27.9 (2015): 095102). The analysis is based on a highly
resolved direct numerical simulation of decaying turbulence. The method of line
segments is used to perform a decomposition of the scalar field into smaller
sub-units based on the extremal points of the scalar along a straight line.
These sub-units (the so-called line segments) are parameterized by their length
and the difference of the scalar field between the ending
points. Line segments can be understood as thin local convective-diffusive
structures in which diffusive processes are enhanced by compressive strain.
From DNS, it is shown that the marginal distribution function of the
length~ assumes complete self-similarity when re-scaled by the mean
length . The joint statistics of and , from which
the local gradient can be defined, play an important role
in understanding the turbulence mixing and flow structure. Large values of
occur at a small but finite length scale. Statistics of are characterized
by rare but strong deviations that exceed the standard deviation by more than
one order of magnitude. It is shown that these events break complete
self-similarity of line segments, which confirms the standard paradigm of
turbulence that intense events (which are known as internal intermittency) are
not self-similar
The multifrequency behaviour of the recurrent nova RS Ophiuchi
This review concentrates on the multifrequency behaviour of RS Ophiuchi and
in particular during its latest outburst. Confirmation of the 1945 outburst,
bipolar outflows and its possible fate as a Type Ia Supernova are discussed.Comment: 5 pages, 5 figures, in The Golden Age of Cataclysmic Variables and
Related Objects, F. Giovannelli & L. Sabau-Graziati (eds.), Mem. SAIt. 83 N.2
(in press
A combined deficiency of tissue factor and PAR-4 is associated with fatal pulmonary hemorrhage in mice
Mice with a complete absence of tissue factor (TF) die during embryonic development whereas mice with low levels of TF (Low-TF mice) survive to adulthood. Low-TF mice exhibit spontaneous hemorrhage in various organs, including the lung. In contrast, mice can survive without protease-activated receptor (PAR)-4, which is the major thrombin receptor on mouse platelets. We determined the effect of combining a deficiency PAR-4 (primary hemostasis) with a deficiency in TF (secondary hemostasis) on embryonic development and survival of adult mice
Old finds-new insights: remarks on two Roman lead ingots from Minas de Riotinto (Huelva, España)
The authors analyze two Roman lead ingots found at Minas de Riotinto and only known by old photographs. Both ingots can be attributed to an entrepreneur involved in the mining business of st century BCLos autores analizan dos lingotes de plomo romanas encontradas en Minas de Riotinto y sólo conocen por fotos antiguas. Ambos lingotes se pueden atribuir a un empresario involucrado en el negocio minero de Cartagena en la primera mitad del siglo primero a.C
Das Erneuerbare-Energien-Gesetz und die Industriestrompreise
Die herrschende Meinung geht davon aus, dass durch die Umlage der Förderung nach dem Erneuerbare-Energien-Gesetz (EEG) auf die Letztverbraucher die Strombezugskosten der Unternehmen steigen und ihre Wettbewerbsfähigkeit sinkt. Wie setzt sich der Strompreis zusammen und wovon ist die Strompreisbildung abhängig? Welche Wirkung hat das EEG auf den Großhandelsstrompreis? --
Costs are not necessarily correlated with threats in conservation landscapes
The priority of an area for conservation is determined by three primary factors: its biodiversity value, the level of threat it is facing, and its cost. Although much attention has been paid to the spatial relationship between biodiversity value and threats, and between biodiversity value and costs, little is known about how costs and threats are spatially correlated. The orthodox assumption in conservation science is that costs and threats are positively correlated. Here, we adapt a classic economic theory of land use to explain how conservation scientists came to expect a positive correlation between costs and threats. We then use high‐resolution, ground‐truthed datasets of land sales and habitat clearance to show that this assumption is false in the state of Queensland, Australia. Our results provide an empirical counterargument to a widespread assumption in conservation science, and illustrate why spatial prioritization needs to include independent measures of costs and threats
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