Effects of human activities of southern giant petrels and skuas in the Antarctic

In der vorliegenden Dissertation wurde die erste umfassende Bewertung aktueller anthropogener Stressoren in Brutgebieten von drei antarktischen Seevogelarten (King George Island, Südshetland Inseln) vorgenommen. Der Südliche Riesensturmvogel Macronectes giganteus gilt als hoch sensible Art im Bezug auf menschliche Aktivitäten (eingestuft als "gefährdet" in der Rote Liste der IUCN). Dagegen sind die Braune Skua Catharacta antarctica lonnbergi und die Südpolarskua C. maccormicki teilweise mit antarktischen Stationen assoziiert und werden daher als weniger sensibel angesehen. Unter Benutzung nicht-invasiver Methoden wurden ethologische und physiologische Stressantworten (Herzschlagrate und Glukokortikoide im Kot) von Brütern, Nichtbrütern und Küken untersucht und dabei Individuen entsprechend ihrer Erfahrung mit Menschen (Gebiete mit hohen, mittleren und niedrigen menschlichen Aktivitäten) verglichen. Diese Ergebnisse und die Analyse anthropogener Effekte auf Reproduktionsparameter führten zu einer Abschätzung des Gefährdungsgrades der Vogelarten und zu spezifischen Managementvorschlägen in ihren Lebensräumen

Diverse MHC IIB allele repertoire increases parasite resistance and body condition in the Long-tailed giant rat (Leopoldamys sabanus)

<p>Abstract</p> <p>Background</p> <p>Genes of the major histocompatibility complex (MHC) code for key functions in the adaptive immune response of vertebrates and most of them show exceptionally high polymorphism. This polymorphism has been associated with the selection by diverse and changing parasite communities. We analysed MHC class IIB diversity, gastrointestinal parasite load and body condition in the wild ranging tropical rat <it>Leopoldamys sabanus </it>(Thomas, 1887) under natural selection conditions in a highly variable rainforest environment in Borneo to explore the mechanisms that maintain these high levels of genetic polymorphism.</p> <p>Results</p> <p>Allelic diversity was determined via SSCP and sequencing, and parasite screening was done through non-invasive faecal egg count. The detected alleles showed expected high levels of polymorphism and balancing selection. Besides a clear advantage for more diverse MHC genotypes in terms of number of alleles, reflected in better body condition and resistance against helminth infection, our data also suggested a positive effect of MHC allele divergence within an individual on these parameters.</p> <p>Conclusion</p> <p>In accordance with the heterozygote advantage hypothesis, this study provides evidence for an advantage of more diverse MHC genotypes. More specifically, the potential negative relation between individual allele divergence and number of parasite species is in line with the '<it>divergent allele advantage</it>' hypothesis.</p

Umstrittene Freihandelsabkommen mit der EU: Afrika unter (Handels-)Druck

In der mitunter emotional aufgeheizten und mit harten Bandagen geführten Debatte um die Freihandelsabkommen zwischen der Europäischen Union (EU) und fünf Ländergruppen Subsahara-Afrikas (SSA) bleiben die Auswirkungen einer wechselseitigen Handelsöffnung heftig umstritten. Klar ist, dass die Abkommen sowohl Chancen als auch Risiken bergen. Fraglich ist, ob der Nutzen den Schaden überwiegen kann. Bislang wurde nur das Wirtschaftspartnerschaftsabkommen (EPA) mit dem Südlichen Afrika ratifiziert und ist am 10. Oktober 2016 in Kraft getreten. Übergangsabkommen mit einzelnen Ländern wurden von Côte d’Ivoire, Ghana, Kamerun, Mauritius, Madagaskar, Simbabwe und den Seychellen ratifiziert. Nach langwierigen Verhandlungen und einer erneuten Verlängerungsfrist bis Anfang des Jahres 2017 ist die Ostafrikanische Gruppe die nächste, deren Unterzeichnung eines regionalen EPAs bevorsteht. Viele der afrikanischen Länder sehen die EPAs als Ausdruck der Vorherrschaft europäischer Wirtschaftsinteressen und Einschränkung ihres politischen Handlungsspielraums. Durch die Öffnung für europäische Importe wird der Druck auf die Landwirtschaft und die wenig entwickelte verarbeitende Industrie in Afrika deutlich steigen. Angesichts der geringen Wettbewerbsfähigkeit der afrikanischen Wirtschaften erscheint die geplante Übergangsphase von 15 bis 20 Jahren utopisch, um internationale Standards zu erreichen. Eine brachiale Umsetzung der EPAs ohne eine beidseitig gestützte massive Anpassungs- und Kompensationsstrategie kann die verletzlichen Ökonomien vieler afrikanischer Länder deutlich schwächen. Fazit: Die afrikanischen Länder sind gefordert, ihre Exportsektoren zu diversifizieren sowie kapazitätsbezogene und infrastrukturelle Probleme anzugehen. Die EU hingegen sollte ihr vages Versprechen einer gleichsamen Handels- und Entwicklungsförderung in klare Unterstützungsmaßnahmen übertragen. Nur dann kann es gelingen, von der wechselseitigen Handelsöffnung zu profitieren und negative Auswirkungen abzufedern

X-ray phase-contrast tomography with a compact laser-driven synchrotron source.

Between X-ray tubes and large-scale synchrotron sources, a large gap in performance exists with respect to the monochromaticity and brilliance of the X-ray beam. However, due to their size and cost, large-scale synchrotrons are not available for more routine applications in small and medium-sized academic or industrial laboratories. This gap could be closed by laser-driven compact synchrotron light sources (CLS), which use an infrared (IR) laser cavity in combination with a small electron storage ring. Hard X-rays are produced through the process of inverse Compton scattering upon the intersection of the electron bunch with the focused laser beam. The produced X-ray beam is intrinsically monochromatic and highly collimated. This makes a CLS well-suited for applications of more advanced--and more challenging--X-ray imaging approaches, such as X-ray multimodal tomography. Here we present, to our knowledge, the first results of a first successful demonstration experiment in which a monochromatic X-ray beam from a CLS was used for multimodal, i.e., phase-, dark-field, and attenuation-contrast, X-ray tomography. We show results from a fluid phantom with different liquids and a biomedical application example in the form of a multimodal CT scan of a small animal (mouse, ex vivo). The results highlight particularly that quantitative multimodal CT has become feasible with laser-driven CLS, and that the results outperform more conventional approaches

Diagnosing and mapping pulmonary emphysema on X-ray projection images

To assess whether grating-based X-ray dark-field imaging can increase the sensitivity of X-ray projection images in the diagnosis of pulmonary emphysema and allow for a more accurate assessment of emphysema distribution. Lungs from three mice with pulmonary emphysema and three healthy mice were imaged ex vivo using a laser-driven compact synchrotron X-ray source. Median signal intensities of transmission (T), dark-field (V) and a combined parameter (normalized scatter) were compared between emphysema and control group. To determine the diagnostic value of each parameter in differentiating between healthy and emphysematous lung tissue, a receiver-operating-characteristic (ROC) curve analysis was performed both on a per-pixel and a per-individual basis. Parametric maps of emphysema distribution were generated using transmission, dark-field and normalized scatter signal and correlated with histopathology. Transmission values relative to water were higher for emphysematous lungs than for control lungs (1.11 vs. 1.06, p<0.001). There was no difference in median dark-field signal intensities between both groups (0.66 vs. 0.66). Median normalized scatter was significantly lower in the emphysematous lungs compared to controls (4.9 vs. 10.8, p<0.001), and was the best parameter for differentiation of healthy vs. emphysematous lung tissue. In a per-pixel analysis, the area under the ROC curve (AUC) for the normalized scatter value was significantly higher than for transmission (0.86 vs. 0.78, p<0.001) and dark-field value (0.86 vs. 0.52, p<0.001) alone. Normalized scatter showed very high sensitivity for a wide range of specificity values (94% sensitivity at 75% specificity). Using the normalized scatter signal to display the regional distribution of emphysema provides color-coded parametric maps, which show the best correlation with histopathology. In a murine model, the complementary information provided by X-ray transmission and dark-field images adds incremental diagnostic value in detecting pulmonary emphysema and visualizing its regional distribution as compared to conventional X-ray projections

Experimental validation of image contrast correlation between ultra-small-angle X-ray scattering and grating-based dark-field imaging using a laser-driven compact X-ray source: Experimentelle Verifizierung des Zusammenhangs zwischen Röntgen-Kleinwinkelstreuung und gitter-basierter Röntgen-Dunkelfeldbildgebung unter Verwendung eines laser-getriebenen Kompaktsynchrotrons

X-ray phase and dark-field contrast have recently been the source of much attention in the field of X-ray imaging, as they both contribute new imaging signals based on physical principles that differ from conventional X-ray imaging. With a so-called Talbot grating interferometer, both phase-contrast and dark-field images are obtained simultaneously with the conventional attenuation-based X-ray image, providing three complementary image modalities that are intrinsically registered. Whereas the physical contrast mechanisms behind attenuation and phase contrast are well understood, a formalism to describe the dark-field signal is still in progress. In this article, we report on correlative experimental results obtained with a grating interferometer and with small-angle X-ray scattering. Furthermore, we use a proposed model to quantitatively describe the results, which could be of great importance for future clinical and biomedical applications of grating-based X-ray imagin

Heterogeneous cavitation from atomically smooth liquid-liquid interfaces

Pressure reduction in liquids may result in vaporization and bubble formation. This thermodynamic process is termed cavitation. It is commonly observed in hydraulic machinery, ship propellers, and even in medical therapy within the human body. While cavitation may be beneficial for the removal of malign tissue, yet in many cases it is unwanted due to its ability to erode nearly any material in close contact. Current understanding is that the origin of heterogeneous cavitation are nucleation sites where stable gas cavities reside, e.g., on contaminant particles, submerged surfaces or shell stabilized microscopic bubbles. Here, we present the finding of a so far unreported nucleation site, namely the atomically smooth interface between two immiscible liquids. The non-polar liquid of the two has a higher gas solubility and acts upon pressure reduction as a gas reservoir that accumulates at the interface. We describe experiments that clearly reveal the formation of cavitation on non-polar droplets in contact with water and elucidate the working mechanism that leads to the nucleation of gas pockets through simulations.Comment: This preprint has not undergone peer review or any post-submission improvements or corrections. The Version of Record of this article is published in Nature Physics, and is available online at https://doi.org/10.1038/s41567-022-01764-

The role of blockchain technologies in digital assessment

Once information is stored on the Blockchain, it cannot be altered retroactively. This immutability makes Blockchain technology an ideal candidate to secure learning achievements and educational credentials. Keeping data trustworthy, secure and manipulation-proof has become an increasing issue in education due to the rise of digital learning environments, which often combine learning experiences, testing procedures and educational credential management. Currently, most digital learning environments safeguard their data using traditional safety systems (e.g. password protection), which in turn are not Blockchain-based, but controlled by a centralized authority. While these centralized systems provide a certain level of security against unauthorized access from outside the system, manipulation from within the system cannot be excluded. Users with high enough access rights (teachers, administrators, system managers) can still add, change or delete entries. This becomes an even greater problem when learning achievements are to be reflected in fair and transparent credit systems, and especially when these educational credits are to be valid across different institutions or even countries. Due to their ability to store data in a decentralized, transparent and manipulation-proof way, Blockchain-based technologies can provide solutions to this problem. The aim of this paper is to describe the status quo of Blockchain technologies in the educational sector, including the expected merits and drawbacks.peer-reviewe

Blockchain technologies as data storage for test results and certificates - the human factor

In the educational sector even the most sophisticated digital environments will not make human interaction obsolete, as learning and education are inherently social processes. This also means that any application that involves learning and assessment must deal with problems resulting from human error. Some of these problems can effectively be countered or excluded by Blockchain-based technologies. Especially in the case of retroactive manipulation of data, non-Blockchain systems are prone to manipulation, as even the most advanced safeguards cannot prohibit users with high enough access rights to manipulate existing data entries (this may be a mere annoyance when a well-meaning teacher edits a student’s attendance, but it can quickly become a large-scale problem when the recognition of diplomas is tampered with on an institutional level). As data stored on the Blockchain cannot be altered retroactively, the problem of tampering with existing data is to be ruled out. This conference paper looks at the role of humans in the use of state-of-the-art systems that store grades from exams and certificates on Blockchain, and aims at initiating a broad discussion whilst providing guidance for future developments.peer-reviewe

Isoforms of Retinol binding protein 4 (RBP4) are increased in chronic diseases of the kidney but not of the liver

<p>Abstract</p> <p>Background</p> <p>The levels of retinol-binding protein 4 (RBP4) – the carrier protein for Vitamin A in plasma – are tightly regulated under healthy circumstances. The kidney, the main site of RBP4 catabolism, contributes to an elevation of RBP4 levels during chronic kidney disease (CKD) whereas during chronic liver disease (CLD) RBP4 levels decrease. Little is known about RBP4 isoforms including apo-RBP4, holo-RBP4 as well as RBP4 truncated at the C-terminus (RBP4-L and RBP4-LL) except that RBP4 isoforms have been reported to be increased in hemodialysis patients. Since it is not known whether CLD influence RBP4 isoforms, we investigated RBP4 levels, apo- and holo-RBP4 as well as RBP4-L and RBP4-LL in plasma of 36 patients suffering from CKD, in 55 CLD patients and in 50 control subjects. RBP4 was determined by ELISA and apo- and holo-RBP4 by native polyacrylamide gel electrophoresis (PAGE). RBP4-L and RBP4-LL were analyzed after immunoprecipitation by mass spectrometry (MALDI-TOF-MS).</p> <p>Results</p> <p>RBP4 isoforms and levels were highly increased in CKD patients compared to controls (P < 0.05) whereas in CLD patients RBP4 isoforms were not different from controls. In addition, in hepatic dysfunction RBP4 levels were decreased whereas the amount of isoforms was not affected.</p> <p>Conclusion</p> <p>The occurrence of RBP4 isoforms is not influenced by liver function but seems to be strongly related to kidney function and may therefore be important in investigating kidney function and related disorders.</p