369 research outputs found
Interdependencies between fossil fuel and renewable energy markets: the German biodiesel market
With this paper, we provide the first quantitative investigation of vertical price transmission in the biodiesel supply chain in Germany with the focus on the developments during the food crisis and the impact of subsidized US biodiesel exports. With the strong promotion of the production and use of biodiesel during the first half of the past decade, the German biodiesel market became the largest national biodiesel market worldwide. This analysis utilizes prices of rapeseed oil, soya oil, biodiesel and crude oil over a sample period covering the rapid growth of the German demand in 2002 until its decline in 2009. The effects of both the market development and different policies on price transmission are analyzed in detail. Due to the numerous changes in the market, a regime-dependent Markov-switching vector error correction model is applied. The results indicate that regimes with differing error-correction behavior govern the transmission process among the various prices. Evidence was found for a strong impact of crude oil price on biodiesel prices, and of biodiesel prices on rapeseed oil prices. However, in both cases, the price adjustment behavior is found to be regime dependent, and the regime occurrence in both market segments shows similar patterns. In relation to crude oil a weak adjustment of biodiesel prices is found to be dominating in the phase of market expansion. This changed from 2007 on when stronger error-correction is found, reflected by a stronger role of the crude oil price developments. In the relationship of biodiesel to the vegetable oils, most of the growth period was dominated by a regime characterized by weak price adjustments. From 2007 on, past own price changes and past changes in soya oil prices had a strong impact particularly on rapeseed oil prices. The biodiesel price development was less important. Reasons for this are substantial changes in the market structure. The biodiesel market developed as an insulated market; biodiesel was mainly produced from rapeseed oil until 2006. Thereafter, biodiesel was increasingly used for blends and sales decreased during the food crisis when agricultural commodity prices rose sharply. At the same time, strong import competition arose from subsidized US B99. The superiority of rapeseed oil for biodiesel production diminished. The uncertainty prevailing in the market from 2007 onwards is reflected by frequent regime changes. --biodiesel,cointegration,nonlinear vector error correction model,regimedependent model,Markov-switching
INVESTIGATING RAPESEED PRICE VOLATILITIES IN THE COURSE OF THE FOOD CRISIS
Multivariate GARCH, MATIF, rapeseed, crude oil, volatilities, food crisis, Demand and Price Analysis, Research Methods/ Statistical Methods, C32, E44, G1, Q11, Q13, Q49,
Attention to the Color of a Moving Stimulus Modulates Motion-Signal Processing in Macaque Area MT: Evidence for a Unified Attentional System
Directing visual attention to spatial locations or to non-spatial stimulus features can strongly modulate responses of individual cortical sensory neurons. Effects of attention typically vary in magnitude, not only between visual cortical areas but also between individual neurons from the same area. Here, we investigate whether the size of attentional effects depends on the match between the tuning properties of the recorded neuron and the perceptual task at hand. We recorded extracellular responses from individual direction-selective neurons in the middle temporal area (MT) of rhesus monkeys trained to attend either to the color or the motion signal of a moving stimulus. We found that effects of spatial and feature-based attention in MT, which are typically observed in tasks allocating attention to motion, were very similar even when attention was directed to the color of the stimulus. We conclude that attentional modulation can occur in extrastriate cortex, even under conditions without a match between the tuning properties of the recorded neuron and the perceptual task at hand. Our data are consistent with theories of object-based attention describing a transfer of attention from relevant to irrelevant features, within the attended object and across the visual field. These results argue for a unified attentional system that modulates responses to a stimulus across cortical areas, even if a given area is specialized for processing task-irrelevant aspects of that stimulus
Bestimmung der Determinanten der Rapspreisentwicklung in der Hochpreisphase auf Basis von Markovzeitreihenmodellen
Der Einfluss der Entwicklungen auf verschiedenen Agrarmärkten auf den deutschen Rapsmarkt wird im vorliegenden Beitrag anhand von multivariaten Zeitreihenmodellen für die Produktpreise untersucht. Da sich in Hochpreisphasen die Preisanpassungsprozesse möglicherweise im Vergleich zu Phasen niedriger Preise ändern, wird auf ein nichtlineares Vektor-Fehlerkorrektur-Modell (VFKM) zurückgegriffen, das regimeabhängige Anpassungen zulässt. Die Spezifikation des Modells als Markovsprung-VFKM (MS-VFKM) erweist sich hier als vorteilhaft, da es keiner a priori Regimespezifizierung und -abgrenzung bedarf. Die Analyse zeigt, dass in den Jahren 2007/08 signifikante Änderungen in den Anpassungsprozessen der Rapspreise im Verhältnis zu anderen Agrargütern auftraten, wobei sowohl Weizen- als auch Sojapreise einen signifikanten Einfluss ausübten. Als entscheidend für das Ausmaß und die Nachhaltigkeit des Rapspreisanstiegs kann hingegen der Abbau von Abweichungen vom langfristigen Gleichgewicht zwischen Rapsöl- und Rapsschrotpreis determiniert werden.Markovsprung-Vektor-Fehlerkorrektur-Modell, regimeabhängiges Verhalten, Rapsmarkt, Hochpreisphase, Research Methods/ Statistical Methods,
Die Beharrlichkeit der Deutungsmuster oder "Warum ist Frau Kludt nicht flexibel?"
Im Rahmen von kritischen Anmerkungen zu einem Beitrag von U. L. Fischer, C. Großer und S. Liebermann über den Einfluss der deutschen Wiedervereinigung auf die subjektiven erwerbsbezogenen Deutungsmuster Ostdeutscher (im gleichen Heft) wird eine Reihe von Einwänden gegen implizite Unterstellungen und zentrale Argumentationen vorgebracht. Fischer und Mitarbeiter können belegen, dass sich entgegen der modernisierungstheoretisch zu erwartenden Flexibilisierung der Subjekte empirisch die subkjektiven Deutungsmuster und Handlungsroutinen nicht verändert haben. Dass dies für erstaunlich gehalten wird, wird allerdings auf eine Reihe theoretischer Missverständnisse der Moderne und der Sozialisation sowie auf die Verkennung konstanter und weniger flexibilitätsfördernder Anforderungen im System von Erwerbsarbeit zurückgeführt. Die unterstellte Beharrlichkeit der Deutungsmuster eines exemplarischen Falls wird zudem in generalisierender Weise den zum Teil einseitig interpretierten realsozialistischen Sozialisationsbedingungen in der DDR zugeschlagen. Dies verweist eher auf die Beharrlichkeit der Deutungsmuster von Fischer und Mitarbeitern im Umgang mit diesem Teil deutscher Geschichte.This paper raises some objections to the argumentation and implicit allegations in the paper of Fischer, Großer and Liebermann in this number. In contrary to the anticipation of flexibility of the subjects following the theory of modernization, the authors notice the empirical evidence of the perseverance of subjective patterns of interpretation and routines of action. In their perspective this is an astonishing result. But this astonishment is based on theoretical misunderstanding of the modem age and socialisation. The authors also don't recognise constant demands in the employment system. The allegation of the "perseverance of pattern of interpretation" in the case of "Frau Kludt" is based on generalised and one-sided interpretations of the socialisation in the former GDR. This shows more likely a "perseverance of pattern of interpretation" in the way the authors cope with this part of German history
A fast and simple assay to quantify bacterial leukotoxin activity
Citation: Oppermann T, S Schwarz, N Busse, P Czermak: A fast and simple assay to quantify bacterial leukotoxin activity, Electronic Journal of Biotechnology, (2016). Vol. 24
http://dx.doi.org/10.1016/j.ejbt.2016.10.001Background: Mannheimia haemolytica is the primary bacterial pathogen in causing bovine respiratory disease with tremendous annual losses in the cattle industry. The leukotoxin from M. haemolytica is the predominant virulence factor. Several leukotoxin activity assays are available but not standardized regarding sample preparation and cell line. Furthermore, these assays suffer from a high standard error, a prolonged time consumption and often complex sample pretreatments, which is important from the bioprocess engineering point of view.
Results: Within this study, an activity assay based on the continuous cell line BL3.1 combined with a commercial available adenosine triphosphate viability assay kit was established. The leukotoxin activity was found to be strongly dependent on the sample preparation. Furthermore, the interfering effect of lipopolysaccharides in the sample could be successfully suppressed by adding polymyxin B. We reached a maximum relative P95 value of 14%, which is more than seven times lower compared to current available assays as well as a time reduction up to 88%.
Conclusion: Ultimately, the established leukotoxin activity assay is simple, fast and has a high reproducibility. Critical parameters regarding the sample preparation were characterized and optimized making complex sample purification superfluous
Proposal of \u3cem\u3eVibrionimonas magnilacihabitans\u3c/em\u3e gen. nov., sp. nov., a Curved Gram Negative Bacterium Isolated From Lake Michigan Water
A mesophilic bacterium appearing as curved rod-shaped cells was isolated from Lake Michigan water. It exhibited highest similarities with Sediminibacterium ginsengisoli DCY13T (94.4 %); Sediminibacterium salmoneum NJ-44T (93.6 %) and Hydrotalea flava CCUG 51397 T (93.1 %) while similarities with other recognized species were sym-homospermidine was the primary polyamine. The major cellular fatty acids were iso-C15 : 1G, iso-C15 : 0, iso-C16 : 0 3-OH and iso-C17 : 0 3-OH, with moderate amounts of iso-C16 : 0. The presence of glycolipids differentiated the novel strains from related genera. The DNA mol% G+C content of the type strain MU-2T was 45.2. Results for other phenotypic and molecular analyses indicated that strain MU-2T is a representative of a novel genus and species for which the name Vibrionimonas magnilacihabitans is proposed. The type strain is MU-2T ( = NRRL B-59231 = DSM 22423)
Comparative Study of Impedance Eduction Methods
The absorption efficiency of acoustic liners used in aircraft engines is characterized by the acoustic impedance. World wide, many grazing ow test rigs and eduction methods are available that provide values for that impedance. However, a direct comparison and assessment of the data of the di erent rigs and methods is often not possible because test objects and test conditions are quite di erent. Only a few papers provide a direct comparison. Therefore, this paper together with a companion paper, present data measured with a reference test object under similar conditions in the DLR and NASA grazing ow test rigs. Additionally, by applying the in-house methods Liner Impedance Non-Uniform ow Solving algorithm (LINUS, DLR) and Convected Helmhholtz Equation approach (CHE, NASA) on the data sets, similarities and differences due to underlying theory are identi ed and discussed
Time domain impedance modelling and applications
AbstractToday, there is a high, often not fully evolved potential of noise attenuation by passive acoustic treatments. Current numerical methods are able to help developing optimal treatments. Thus, the simulation of acoustic lining in aeroengines is one of the core objectives for the development of modern CAA solvers. Here, the opportunities of the Extended Helmholtz Resonator (EHR) model of Rienstra in the time domain in this design and optimisation process are demonstrated. The optimization of a lining for a specific application as the obvious objective is still out of reach for many cases with current numerical resources. However, the model allows the optimisation towards the dissipation characteristics in an impedance flow tube measurement with a physical liner sample, which provides the numerical parameters of the liner for high fidelity CAA simulations. Moreover, the model parameters are related to the cell geometry and face sheet of the liner panel. An example is provided for the purely numerical prediction of the attenuation in the complex flow of an aeroengine duct. This is demonstrated by considering the resulting parameters in modal axisymmetric and three dimensional simulations of the rearward sound radiation from a lined bypass duct. The example demonstrates, that the optimisation of the liner properties is not achievable in a justifiable time, even if simplified two dimensional conditions are considered. A possible solution to this problem is to use the computational power of a graphics processing unit (GPU). The development of pixel shaders which implement a large number of parallel processors into the GPU, shows a much more agile growth than any CPU based system does. As an outlook, a platform independent implementation of a GPU based CAA solver with impedance boundary condition and the capability to handle axisymmetric duct geometries is presented. It demonstrates a speed up by a factor > 100
Feature-based attentional integration of color and visual motion
In four variants of a speeded target detection task, we investigated the processing of color and motion signals in the human visual system. Participants were required to attend to both a particular color and direction of motion in moving random dot patterns (RDPs) and to report the appearance of the designated targets. Throughout, reaction times (RTs) to simultaneous presentations of color and direction targets were too fast to be reconciled with models proposing separate and independent processing of such stimulus dimensions. Thus, the data provide behavioral evidence for an integration of color and motion signals. This integration occurred even across superimposed surfaces in a transparent motion stimulus and also across spatial locations, arguing against object-and location-based accounts of attentional selection in such a task. Overall, the pattern of results can be best explained by feature-based mechanisms of visual attention
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