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

The Effect of the German Renewable Energy Act (EEG) on "the Electricity Price"

Many technologies that produce electricity from renewable energy sources are currently not competitive. This is due to the fact that their generation cost is higher than that of conventional thermal power plants. Nevertheless, since using renewable energies has a number of positive effects, these installations have been supported by German public policy for many years. This support is currently demonstrated very successfully by the German Renewable Energy Act (EEG), which provides for fixed feed-in tariffs (FITs). The costs of this support scheme are distributed to the electricity consumers. Due to the so-called EEG levy, electricity costs of industry are increased and as a result their competitiveness is decreased. Consequently, electricity intensive enterprises have protested against the levy on a regular basis and finally achieved a reduction of the levy. However, the potential effect of the EEG on the wholesale price for ele ctricity has not yet been considered. Against this background, we analyze the effect of the EEG on electricity prices in a perfect market. We will show that the support of electricity production from renewable energy decreases the wholesale price of electricity. Consequently, electricity costs of companies that are subject to the reduced EEG levy may decrease too

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 $\ell$ and the difference $\Delta\phi$ 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~$\ell$ assumes complete self-similarity when re-scaled by the mean length $\ell_m$. The joint statistics of $\Delta\phi$ and $\ell$, from which the local gradient $g=\Delta\phi/\ell$ can be defined, play an important role in understanding the turbulence mixing and flow structure. Large values of $g$ occur at a small but finite length scale. Statistics of $g$ 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

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

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? --

The Radio Light Curve of the Gamma-Ray Nova in V407 Cyg: Thermal Emission from the Ionized Symbiotic Envelope, Devoured from Within by the Nova Blast

We present multi-frequency radio observations of the 2010 nova event in the symbiotic binary V407 Cygni, obtained with the Karl G. Jansky Very Large Array and spanning 1-45 GHz and 17-770 days following discovery. This nova---the first ever detected in gamma rays---shows a radio light curve dominated by the wind of the Mira giant companion, rather than the nova ejecta themselves. The radio luminosity grew as the wind became increasingly ionized by the nova outburst, and faded as the wind was violently heated from within by the nova shock. This study marks the first time that this physical mechanism has been shown to dominate the radio light curve of an astrophysical transient. We do not observe a thermal signature from the nova ejecta or synchrotron emission from the shock, due to the fact that these components were hidden behind the absorbing screen of the Mira wind. We estimate a mass loss rate for the Mira wind of Mdot_w ~ 10^-6 M_sun/yr. We also present the only radio detection of V407 Cyg before the 2010 nova, gleaned from unpublished 1993 archival VLA data, which shows that the radio luminosity of the Mira wind varies by a factor of >~20 even in quiescence. Although V407 Cyg likely hosts a massive accreting white dwarf, making it a candidate progenitor system for a Type Ia supernova, the dense and radially continuous circumbinary material surrounding V407 Cyg is inconsistent with observational constraints on the environments of most Type Ia supernovae.Comment: Resubmitted to ApJ after incorporating referee's comment