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We take a simple time-series approach to modeling and forecasting daily average temperature in U.S. cities, and we inquire systematically as to whether it may prove useful from the vantage point of participants in the weather derivatives market. The answer is, perhaps surprisingly, yes. Time-series modeling reveals conditional mean dynamics, and crucially, strong conditional variance dynamics, in daily average temperature, and it reveals sharp differences between the distribution of temperature and the distribution of temperature surprises. As we argue, it also holds promise for producing the long-horizon predictive densities crucial for pricing weather derivatives, so that additional inquiry into time-series weather forecasting methods will likely prove useful in weather derivatives contexts.
Unmasking a temperature-dependent effect of the P. anserina i-AAA protease on aging and development
(2011)
Different molecular pathways involved in maintaining mitochondrial function are of fundamental importance to control cellular homeostasis. Mitochondrial i-AAA protease is part of such a surveillance system, and PaIAP is the putative ortholog in the fungal aging model Podospora anserina. Here, we investigate the role of PaIAP in aging and development. Deletion of the gene encoding PaIAP resulted in a specific phenotype. When incubated at 27°C, spore germination and fruiting body formation are not different from that of the corresponding wild-type strain. Unexpectedly, the lifespan of the deletion strain is strongly increased. In contrast, cultivation at an elevated temperature of 37°C leads to impairments in spore germination and fruiting body formation and to a reduced lifespan. The higher PaIAP abundance in wild-type strains of the fungus grown at elevated temperature and the phenotype of the deletion strain unmasks a temperature-related role of the protein. The protease appears to be part of a molecular system that has evolved to allow survival under changing temperatures, as they characteristically occur in nature.
The rapidity distribution of thermal photons produced in Pb+Pb collisions at CERN-SPS energies is calculated within scaling and three- fluid hydrodynamics. It is shown that these scenarios lead to very different rapidity spectra. A measurement of the rapidity dependence of photon radiation can give cleaner insight into the reaction dynamics than pion spectra, especially into the rapidity dependence of the temperature.
In the literature, various environmental factors are described as being capable of influencing the reproductive output of insect females irrespective of their body size. Still, female body size or weight is widely used as a proxy for fecundity. In the present study, a seven-year data set on the autumnal moth, Epirrita autumnata (Borkhausen) (Lepidoptera: Geometridae), was used to analyze whether the body weight-fecundity relationship in this capital breeding, cyclic forest defoliating lepidopteran is constant across years. Ambient temperature conditions and density of conspecifics during larval development, the length of the pupal period, as well as moth densities in the parent generation were examined as factors capable of modifying the body weight-fecundity relationship. While the regression slope of potential fecundity (total egg numbers per female) on pupal mass was constant across years, the mean total egg number per given body weight (the regression intercept) was significantly different between years. This residual variance in egg numbers after controlling for the effect of pupal mass was best explained by the pooled geometrid density (autumnal and winter moths) in the parent generation. The total egg number per given body weight decreased with increasing density of geometrid moths in the parent generation. Thus, maternal density effects on offspring fecundity were found in this system. Their rather weak nature suggests, however, that this maternal effect alone does not have the potential of causing cyclic population dynamics in the autumnal moth.
This work is dedicated to the investigation of nuclear matter at non-zero temperatures within an effective hadronic model based on the Walecka model. It includes fermions as well as a vector omega meson and a scalar sigma meson where for the latter a quartic self-interaction has been considered. The coupling constants have been adapted to the saturation properties of infinite nuclear matter. A set of self-consistent Schwinger-Dyson equations has been set up for all included particles within the Cornwall-Jackiw-Tomboulis formalism. This has been expanded to non-zero temperatures via the imaginary time formalism. Beside tree-level two different stages of approximations have been considered: the Hartree approximation which takes into account the double-bubble diagram for the scalar meson, and an improved approximation where in addition two-particle irreducible sunset diagrams for all fields were included. In the Hartree-approximation the Schwinger-Dyson equations can be solved by quasi-particle ansaetze, while in the improved approximation spectral functions with non-zero widths have to be introduced. The Schwinger-Dyson equations are solved by the fully dressed propagators. Comparing the two levels of approximation shows the influence of finite widths on the temperature dependence of the particle properties. The consideration of finite widths in fact has a significant influence on the transition from a phase of heavy nucleons to a transition of light nucleons, observed in the Walecka-model. The temperature dependence is weakend when finte widths are taken into account.
The modification of the width of the rho meson due to in-medium decays and collisions is evaluated. In high temperature and/or high density hadronic matter, the collision width is much larger than the one-loop decay width. The large width of the meson in matter seems to be consistent with some current interpretations of the e+e mass spectra measured at the CERN/SPS.
The aim of this study was to assess the invasion risk of freshwater habitats and determine the environmental variables that are most favorable for the establishment of alien amphipods, isopods, gastropods, and bivalves. A total of 981 sites located in streams and rivers in Germany. Therefore we analyzed presence-absence data of alien and indigenous amphipods, isopods, gastropods, and bivalves from 981 sites located in small to large rivers in Germany with regard to eight environmental variables: chloride, ammonium, nitrate, oxygen, orthophosphate, distance to the next navigable waterway, and maximum and minimum temperature. Degraded sites close to navigable waters were exposed to an increased invasion risk by all major groups of alien species. Moreover, invaded sites by all four groups of alien species were similar, whereas the sites where indigenous members of the four groups occurred were more variable. Increased temperature and chloride concentration as well as decreased oxygen concentration were identified as major factors for the invasibility of a site. Species-specific analyses showed that chloride was among the three most predictive environmental variables determining species assemblage in all four taxonomic groups. Also distance to the next navigable waterways was similarly important. Additionally, the minimum temperature was among the most important variables for amphipods, isopods, and bivalves. The bias in the occurrence patterns of alien species toward similarly degraded habitats suggests that the members of all four major groups of freshwater alien species are a non-random, more tolerant set of species. Their common tolerance to salinity, high temperature, and oxygen depletion may reflect that most alien species were spread in ballast water tanks, where strong selective pressures, particularly temperature fluctuations, oxygen depletion, and increased salinity may create a bottleneck for successful invasion. Knowledge on the major factors that influence the invasion risk of a habitat is needed to develop strategies to limit the spread of invasive species.
Momilactones A and B (MA and MB, respectively) are phytoalexins and plant growth inhibitors available in rice husks. However, to date, the isolation and purification of the two compounds have been complicated, laborious, and less effective. The present study was conducted to establish a protocol to simplify and optimize quantities of MA and MB by combinations of ethyl acetate (EtOAc), distilled water, methanol (MeOH), temperature, and pressure for extractions. At a temperature of 100 °C, combined with EtOAc and MeOH 100%, MA and MB were enriched in greater quantities than non-treated rice husks, of which MB was much augmented than MA. The EtOAc extract obtained from samples dried at 100 °C for 1 h, then placed in MeOH 100% for 1 week, provided maximum yields of MA [58.76 µg/g dry weight (DW)] and MB (104.43 µg/g DW). The use of pressure effectively enhanced yields of MA (17.90–26.26 µg/g DW) and MB (40.78–71.0 µg/g DW). The actual purified amounts of MA and MB increased by 5 and 15 folds, respectively. The use of either sole distilled water or MeOH ≤ 50% at any temperature did not successfully isolate both MA and MB. The yield optimization aids to easier and more productive purification of the two compounds, and thus extends researches on biological activities of MA and MB, including pharmaceutical and medicinal properties.
In dieser Arbeit wurden die neuronalen Glutamattransporter EAAT4 (Excitatory Amino Acid Transporter) und EAAT3 in einem HEK (Human Embryonic Kidney) Zellsystem untersucht, in dem die Transporter transient exprimiert wurden. Diese Proteine katalysieren den Transport von Glutamat entgegen des Konzentrationsgradienten aus dem Extrazellulärraum in das Zytosol. Die Energie des Transports, stammt aus dem Kotransport von Natriumionen und Protonen und dem Gegentransport von Kaliumionen. Für EAAT3 ist bekannt, dass das Verhältnis 3 Na+:1 H+:1 Glutamat:1 K+ beträgt, wodurch 2 positive Ladungen pro Transportzyklus verschoben werden. Das führt zu einem messbaren positiven Einwärtststrom. Dieser Strom ist für EAAT4 wesentlich schwächer und die Stöchiometrie ist unbekannt. Beide Proteine besitzen eine Anionenkanaleigenschaft, die bei der Bindung von Na+ und der Bindung von Glutamat voll aktiviert wird. Diese Eigenschaft ist bei EAAT4 besonders ausgeprägt. Die Transporter wurden in Abhängigkeit von verschiedenen intra- und extrazellulären Ionen- und Substratkompositionen, sowie bestimmter Potentialen und der Temperatur elektrophysiologisch charakterisiert. Die Charakterisierung der stationären Eigenschaften des wenig bekannten Transporters EAAT4 brachten Erkenntnisse zu Tage, die 1) Klarheit über die apparenteAffinitäten der Substrate, insbesondere Glutamat und Na+ bringen 2) neu in Bezug auf die Spannungsabhängigkeit der apparenten Affinität von Glutamat sind. Die Untersuchung der vorstationären Ableitungen waren fruchtbar in Bezug auf a) die Ähnlichkeit des Transports, der durch EAAT4 katalysiert wird, zu anderen Glutamattransporter b) spezifische Parameter des Transports, wie den Unterschied in der Transportgeschwindigkeit c) die neuartige Kinetik der Anionenleitfähigkeit. Aus den Daten ergibt sich folgendes Bild über den Mechanismus des Transports. Die Substrate binden an EAAT4, im Vergleich zu den anderen Transportern, mit wesentlich höheren Km [ (0,6 ± 0,1)µM für Glutamat und (42,3 ± 5,2)mM für Na+]. Die Bindung von Glutamat, die schnell verläuft, ist, wie bei EAAT3, stark Na+ abhängig, genau wie die Leckleitfähigkeit, die ebenfalls durch Na+ aktiviert wird. Die folgenden glutamatabhängigen, vorstationären Reaktionen, inklusive der Translokation der Substrate verläuft wesentlich langsamer, als in anderen Transportersubtypen. Die Folge ist eine geringe Umsatzrate (<3 1/s) und daher ein geringer Transportstrom [(-3,6 ± 2,8)pA]. Die Daten zeigen, dass EAAT4 trotzallem denselben prinzipiellen Mechanismus, wie die anderen Subtypen folgt. Das Verhalten der Anionenleitfähigkeit zeigt allerdings erhebliche Unterschiede zu anderen Subtypen, da die Anionenleitfähigkeit durch negative Membranpotentiale inhibiert wird. Dies wird durch die Inhibierung der K+-Relokationsreaktion des Transporters erklärt. Zusammengenommen spricht die geringe Umsatzrate und die hohe apparente Affinität für Glutamat dafür, dass EAAT4 ein hochspezialisierter Transporter für die schnelle Pufferung von Glutamat und den langfristigen Transport von Glutamat bei niedrigen Konzentrationen ist. Im zweiten Teil dieser Arbeit wurde die Temperaturabhängigkeit des Glutamattransports durch EAAT3 untersucht. Die Temperaturabhängigkeit des Transports unter stationären Bedingungen zeigte interessante neue Ergebnisse. Die Ergebnisse lassen Aussagen zu bezüglich 1) der Thermodynamik der Bindung der Substrate und 2) der molekularen Natur bestimmter Teilreaktionen im Zyklus Die Bindung eines nicht-transportierbaren Glutamatanalogons zeigt, dass die Inhibitorbindung exotherm ist (H = 30,0 ± 3,3)kJ/mol. Die Bindung von Na+ an den unbeladenen Transporter ist im Gegensatz dazu nicht signifikant von der Temperatur abhängig mit H = (20,8 ± 21,5)kJ/mol. Es ist ebenfalls interessant, dass die Freie Enthalpie des Gesamtzyklus beiEAAT4 signifikant grösser ist als bei EAAT3, was in Übereinstimmung mit der höheren, apparenten Glutamataffinität ist [GEAAT4 = (35 ± 1)kJ/mol vs. .GEAAT3 = (30 ±1)kJ/mol]. Die Temperaturabhängigkeit der vorstationären Kinetik von EAAT3 enthüllt gleichfalls neue Ergebnisse. Zum einen ist die Bindung des Na+ Ions and den unbeladenen Transporter mit einer Konformationsänderung begleitet. Im Gegensatz dazu hat die Reaktion, die der Glutamatbindung zugeordnet wurde, nur eine moderate Aktivierungsenthalpie [H‡ = (39 ± 23 )kJ/mol], wie für eine diffusionskontrollierte Reaktion erwartet wird. Die nachfolgenden zwei langsameren Phasen des Transportstroms, die in der Literatur der Aktivierung der Anionenleitfähigkeit und der Glutamattranslokation zugeordnet wurden, sind mit hohen Aktivierungsenthalpien verbunden [H‡ = (121 ± 12)kJ/mol bzw. (94 ± 4)kJ/mol]. Dies bedeutet zum einen, dass zur Öffnung des Anionenkanals und der Translokation von Glutamat eine grössere Umstrukturierung des Transporters notwendig ist. Durch die hier gefundenen, neuen Daten für die Translokationsgeschwindigkeit bei physiologischen Temperaturen kann die Hypothese in Frage gestellt werden, die besagt, dass Glutamattransporter nicht schnell genug seien, um zur schnellen Entfernung des Glutamats nach der synaptischen Transmission beizutragen. Es scheint vielmehr so, dass bei physiologischen Temperaturen und Membranpotentialen, die Translokation von Glutamat hinreichend schnell verläuft.
Previous studies detected an influence of urban characteristics on song traits in passerine birds, that is, song adjustments to ambient noise in urban areas. Several studies already described the effect of weather conditions on the behavior of birds, but not the effect on song traits. We investigate, if song trait variability changes along a continuous urbanity gradient in Frankfurt am Main, Germany. We examined, for the first time on a larger scale, the influence of weather on song parameters. We made song recordings of three common passerine species: the blue and great tit (Cyanistes caeruleus (Linnaeus, 1758) and Parus major Linnaeus, 1758) and the European blackbird (Turdus merula Linnaeus, 1758). We measured different song traits and performed statistical analyses and modeling on a variety of variables—among them urbanity and weather parameters. Remarkably, we found only few cases of a significant influence of urbanity parameters on song traits. The influence of weather parameters (air pressure, atmospheric humidity, air and soil temperatures) on song traits was highly significant. Birds in Frankfurt face high noise pollution and might show different adaptations to high noise levels. The song trait variability of the investigated species is affected more by weather conditions than by urban characteristics in Frankfurt. However, the three species react differently to specific weather parameters. Smaller species seem to be more affected by weather than larger species.