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Die Frage, ob das Klima extremer wird, beschäftigt Wissenschaft und Öffentlichkeit mit zunehmender Intensität. Daher ist hier eine extremwertstatistische Untersuchung hinsichtlich Niederschlag und Temperatur durchgeführt worden. Dabei werden, entsprechend IPCCEmpfehlungen, für die untersuchten Zeitreihen obere und untere Schwellenwerte festgelegt. Durch Auszählen kann dann ermittelt werden, wie oft die entsprechende Schranke über- oder unterschritten wurde (relativer Extremwert). Das Verhältnis der Anzahl der relativen Extremwerte zu den Gesamtwerten nennt man empirische Extremwerthäufigkeit. Darüber hinaus wurden Häufigkeitsverteilungen an die Datensätze angepasst, aus denen vorher der Jahresgang eliminiert wurde. Über diese Häufigkeitsverteilungen bestimmt man die theoretische Über- oder Unterschreitungswahrscheinlichkeit der jeweiligen Schranke, und vergleicht diese mit der empirischen. Diese Daten bieten auch die Möglichkeit, weitere wahrscheinlichkeitstheoretische Größen (Risiko, Wartezeitverteilung, Wiederkehrzeit) zu bestimmen. Das Verfahren wird auf 78 100-jährige Zeitreihen des Niederschlags und 10 100-jährige Zeitreihen der Temperatur in Deutschland angewendet. Dabei ist zu beachten, dass eine Übereinstimmung von empirischen und theoretischen Ergebnissen nur im statistischen Mittel zu erwarten ist. Die Untersuchungen zeigen, dass die ersten 10 bis 15 Jahre des letzten Jahrhunderts, sowohl bei den Niederschlägen als auch bei der Temperatur, nicht so extrem gewesen sind wie der Rest des Jahrhunderts. Bei den Niederschlagsdaten zeigt sich darüber hinaus um die Jahrhundertmitte ein etwa 10-jähriger Zeitraum mit hoher Niederschlagsvariabilität. Für die Abschätzung der Wahrscheinlichkeit des Überschreitens von Schranken bei Niederschlagsdaten ist die angepasste Gumbelverteilung am besten geeignet. Der Unterschied zu den anderen angepassten Verteilungen ist um so klarer, je höher die Schranke gewählt wird. Für die Abschätzung der Wahrscheinlichkeit des Unterschreitens von Schranken bei Temperaturdaten ist die angepasste Weibullverteilung am besten geeignet. Kein klares Bild ergibt sich bei den Kombinationen untere Schranke und Niederschlagsdaten sowie obere Schranke und Temperaturdaten. Die Abschätzung der Eintrittswahrscheinlichkeit und damit verbunden die Bestimmung der Wiederkehrzeit und des Risikos ist in allen Fällen um so besser, je geringer der Jahresgang der Variabilität der untersuchten Größe ist. Beim Trend der Wiederkehrzeit zeigt sich bei den Niederschlagsdaten und der unteren Schranke im äußersten Westen Deutschlands ein Rückgang trockener Ereignisse. Ansonsten erkennt man nur schwache Änderungen. Für obere Schranken zeigt sich im Westen Deutschlands ein Rückgang der Wiederkehrzeit, also ein Trend zu häufigeren extremen Niederschlägen, mit einem Maximum im östlichen Nordrhein-Westfalen. Im Osten dagegen ermittelt man einen Rückgang extremer Niederschläge und damit einen Trend zu trockenerer Witterung, am stärksten ausgeprägt im westlichen Erzgebirge. Für die Temperaturdaten zeigt sich in fast ganz Deutschland für untere Schranken ein Anstieg der Wiederkehrzeit. Extrem niedrige Temperaturen treten also tendenziell seltener auf. Die Ausnahme bilden hier nur, je nach zugrunde liegender Verteilung, der (äußerste) Norden und Osten Deutschlands. Die gleiche geographische Unterteilung, jedoch mit umgekehrtem Trend, zeigt sich bei den oberen Schranken. Extrem warme Ereignisse treten, mit Ausnahme des Nordostens, tendenziell häufiger auf. Die stärkste Zunahme im Trend der warmen Ereignisse zeigt sich dabei im Südwesten Deutschlands.
Background: Interferon and ribavirin therapy for chronic hepatitis C virus (HCV) infection yields sustained virological response (SVR) rates of 50–80%. Several factors such as non-1 genotype, beneficial IL28B genetic variants, low baseline IP-10, and the functionality of HCV-specific T cells predict SVR. With the pending introduction of new therapies for HCV entailing very rapid clearance of plasma HCV RNA, the importance of baseline biomarkers likely will increase in order to tailor therapy. CD26 (DPPIV) truncates the chemokine IP-10 into a shorter antagonistic form, and this truncation of IP-10 has been suggested to influence treatment outcome in patients with chronic HCV infection patients. In addition, previous reports have shown CD26 to be a co-stimulator for T cells. The aim of the present study was to assess the utility of CD26 as a biomarker for treatment outcome in chronic hepatitis C and to define its association with HCV-specific T cells.
Methods: Baseline plasma from 153 genotype 1 and 58 genotype 2/3 infected patients enrolled in an international multicenter phase III trial (DITTO-HCV) and 36 genotype 1 infected patients participating in a Swedish trial (TTG1) were evaluated regarding baseline soluble CD26 (sCD26) and the functionality of HCV-specific CD8+ T cells.
Results: Genotype 1 infected patients achieving SVR in the DITTO (P = 0.002) and the TTG1 (P = 0.02) studies had lower pretreatment sCD26 concentrations compared with non-SVR patients. Sixty-five percent of patients with sCD26 concentrations below 600 ng/mL achieved SVR compared with 39% of the patients with sCD26 exceeding 600 ng/mL (P = 0.01). Patients with sCD26 concentrations below 600 ng/mL had significantly higher frequencies of HCV-specific CD8+ T cells (P = 0.02).
Conclusions: Low baseline systemic concentrations of sCD26 predict favorable treatment outcome in chronic HCV infection and may be associated with higher blood counts of HCV-specific CD8+ T cells.
Mosquitoes and other arthropods may transmit medically important pathogens, in particular viruses such as West Nile virus. The presence of suitable hosts and competent vectors for those zoonotic viruses is essential for an enzootic transmission, which is a prerequisite for epidemics. To establish reliable risk projections, it is an urgent need for an exact identification of mosquito species, which is especially challenging in the case of sibling species, such as Culex. pipiens pipiens biotypes pipiens and molestus. To facilitate detection of different Culex pipiens forms and their hybrids we established a multiplex real-time PCR. Culex pipiens samples were obtained by egg raft collection and rearing until imago stage or adult sampling using CO2 baited traps and gravid traps. In total, we tested more than 16,500 samples collected all over Germany in the years 2011 and 2012. The predominant species in Germany are Culex pipiens pipiens biotype pipiens and Culex. torrentium, but we also detected Culex pipiens pipiens biotype molestus and hybrids of the two pipiens biotypes at sites where both species occur sympatrically. This report of a potentially important bridge vector for West Nile virus might have major impact in the risk projections for West Nile virus in Germany.
Small-scale phenotypic differentiation along complex stream gradients in a non-native amphipod
(2019)
Background: Selective landscapes in rivers are made up by an array of selective forces that vary from source to downstream regions or between seasons, and local/temporal variation in fitness maxima can result in gradual spatio-temporal variation of phenotypic traits. This study aimed at establishing freshwater amphipods as future model organisms to study adaptive phenotypic diversification (evolutionary divergence and/or adaptive plasticity) along stream gradients.
Methods: We collected Gammarus roeselii from 16 sampling sites in the Rhine catchment during two consecutive seasons (summer and winter). Altogether, we dissected n = 1648 individuals and quantified key parameters related to morphological and life-history diversification, including naturally selected (e.g., gill surface areas) as well as primarily sexually selected traits (e.g., male antennae). Acknowledging the complexity of selective regimes in streams and the interrelated nature of selection factors, we assessed several abiotic (e.g., temperature, flow velocity) and biotic ecological parameters (e.g., conspecific densities, sex ratios) and condensed them into four principal components (PCs).
Results: Generalized least squares models revealed pronounced phenotypic differentiation in most of the traits investigated herein, and components of the stream gradient (PCs) explained parts of the observed differences. Depending on the trait under investigation, phenotypic differentiation could be ascribed to variation in abiotic conditions, anthropogenic disturbance (influx of thermally polluted water), or population parameters. For example, female fecundity showed altitudinal variation and decreased with increasing conspecific densities, while sexual dimorphism in the length of male antennae—used for mate finding and assessment—increased with increasing population densities and towards female-biased sex ratios.
Conclusions: We provide a comprehensive protocol for comparative analyses of intraspecific variation in life history traits in amphipods. Whether the observed phenotypic differentiation over small geographical distances reflects evolutionary divergence or plasticity (or both) remains to be investigated in future studies. Independent of the mechanisms involved, variation in several traits is likely to have consequences for ecosystem functions. For example, leaf-shredding in G. roeselii strongly depends on body size, which varied in dependence of several ecological parameters.
Pathologic data indicate that human cytomegalovirus (HCMV) infection might be associated with the pathogenesis of several human malignancies. However, no definitive evidence of a causal link between HCMV infection and cancer dissemination has been established to date. This study describes the modulation of the invasive behavior of NCAM-expressing tumor cell lines by HCMV. Neuroblastoma (NB) cells, persistently infected with the HCMV strain AD169 (UKF-NB-4AD169 and MHH-NB-11AD169), were added to endothelial cell monolayers and adhesion and penetration kinetics were measured. The 140- and 180-kDa isoforms of the adhesion receptor NCAM were evaluated by flow cytometry, Western blot, and reverse transcriptionpolymerase chain reaction (RT-PCR). The relevance of NCAM for tumor cell binding was proven by treating NB with NCAM antisense oligonucleotides or NCAM transfection. HCMV infection profoundly increased the number of adherent and penetrated NB, compared to controls. Surface expression of NCAM was significantly lower on UKF-NB-4AD169 and MHH-NB-11AD169, compared to mock-infected cells. Western-blot and RT-PCR demonstrated reduced protein and RNA levels of the 140- and 180-kDa isoform. An inverse correlation between NCAM expression and adhesion capacity of NB has been shown by antisense and transfection experiments. We conclude that HCMV infection leads to downregulation of NCAM receptors, which is associated with enhanced tumor cell invasiveness.
Chirality is omnipresent in living nature. On the single molecule level, the response of a chiral species to a chiral probe depends on their respective handedness. A prominent example is the difference in the interaction of a chiral molecule with left or right circularly polarized light. In the present study, we show by Coulomb explosion imaging that circularly polarized light can also induce a chiral fragmentation of a planar and thus achiral molecule. The observed enantiomer strongly depends on the orientation of the molecule with respect to the light propagation direction and the helicity of the ionizing light. This finding might trigger new approaches to improve laser-driven enantioselective chemical synthesis.
Since its founding in 1993 the International Long-term Ecological Research Network (ILTER) has gone through pronounced development phases. The current network comprises 44 active member LTER networks representing 700 LTER Sites and ~ 80 LTSER Platforms across all continents, active in the fields of ecosystem, critical zone and socio-ecological research. The critical challenges and most important achievements of the initial phase have now become state-of-the-art in networking for excellent science. At the same time increasing integration, accelerating technology, networking of resources and a strong pull for more socially relevant scientific information have been modifying the mission and goals of ILTER. This article provides a critical review of ILTER's mission, goals, development and impacts. Major characteristics, tools, services, partnerships and selected examples of relative strengths relevant for advancing ILTER are presented. We elaborate on the tradeoffs between the needs of the scientific community and stakeholder expectations. The embedding of ILTER in an increasingly collaborative landscape of global environmental observation and ecological research networks and infrastructures is also reflected by developments of pioneering regional and national LTER networks such as SAEON in South Africa, CERN/CEOBEX in China, TERN in Australia or eLTER RI in Europe. The primary role of ILTER is currently seen as a mechanism to investigate ecosystem structure, function, and services in response to a wide range of environmental forcings using long-term, place-based research. We suggest four main fields of activities and advancements for the next decade through development/delivery of a: (1) Global multi-disciplinary community of researchers and research institutes; (2) Strategic global framework and strong partnerships in ecosystem observation and research; (3) Global Research Infrastructure (GRI); and (4) a scientific knowledge factory for societally relevant information on sustainable use of natural resources.
Chatbots become human(like): the influence of gender on cooperative interactions with chatbots
(2019)
CURRENT TECHNOLOGICAL ADVANCEMENTS OF CONVERSATIONAL AGENTS (CAs) PROMISE NEW POTENTIALS FOR HUMAN-COMPUTER COLLABORATIONS. YET, BOTH PRACTITIONERS AND RESEARCHERS FACE CHALLENGES IN DESIGNING THESE INFORMATION SYSTEMS, SUCH THAT CAs NOT ONLY INCREASE IN INTELLIGENCE BUT ALSO IN EFFECTIVENESS. THROUGH OUR RESEARCH ENDEAVOUR, WE PROVIDE NEW AND COUNTERINTUITIVE INSIGHTS THAT ARE CRUCIAL FOR THE EFFECTIVE DESIGN OF COOPERATIVE CAs.
The genome, antigens of human cytomegalovirus (HCMV) are frequently found in prostatic carcinoma. However, whether this infection is causative or is an epiphenomenon is not clear. We therefore investigated the ability of HCMV to promote metastatic processes, defined by tumor cell adhesion to the endothelium, extracellular matrix proteins. Experiments were based on the human prostate tumor cell line PC3, either infected with the HCMV strain Hi (HCMVHi) or transfected with cDNA encoding the HCMV-specific immediate early protein IEA1 (UL123) or IEA2 (UL122). HCMVHi upregulated PC3 adhesion to the endothelium, to the extracellular matrix proteins collagen, laminin, fibronectin. The process was accompanied by enhancement of β1-integrin surface expression, elevated levels of integrin-linked kinase, phosphorylation of focal adhesion kinase. IEA1 or IEA2 did not modulate PC3 adhesion or β1-integrin expression. Based on this in vitro model, we postulate a direct association between HCMV infection, prostate tumor transmigration, which is not dependent on IEA proteins. Integrin overexpression, combined with the modulation of integrin-dependent signalling, seems to be, at least in part, responsible for a more invasive PC3Hi tumor cell phenotype. Elevated levels of c-myc found in IEA1-transfected or IEA2-transfected PC3 cell populations might promote further carcinogenic processes through accelerated cell proliferation.