Nuclear Masses in Astrophysics

Among all nuclear ground-state properties, atomic masses are highly specific for each particular combination of N and Z and the data obtained apply to a variety of physics topics. One of the most crucial questions to be addressed in mass spectrometry of unstable radionuclides is the one of understanding the processes of element formation in the Universe. To this end, accurate atomic mass values of a large number of exotic nuclei participating in nucleosynthesis are among the key input data in large-scale reaction network calculations. In this paper, a review on the latest achievements in mass spectrometry for nuclear astrophysics is given.Comment: Proceedings of the 10th Symposium on Nuclei in the Cosmos, NIC X - Mackinac Island, Michigan, USA (10 pages, 4 figures

Complement-mediated neuronal loss by sialic acid glycocalyx alterations

Every neuronal cell is covered with a dense structure of glycoconjugates, the glycocalyx. Sialic acids form the terminal ends of the glycocalyx and thus, are more accessible for the cellular environment. Microglia, the brain macrophages constantly survey the brain parenchyma and can sense small alterations in the glycocalyx. Recently, it was demonstrated in murine and human neuron-microglia/macrophage co-cultures that healthy neurons with reduced surface-bound sialic acids were removed by microglia/macrophages in a complement-dependent manner. Although microglial phagocytosis is considered as beneficial, the role of microglia in recognizing sialic acids in neurodegenerative and neuroinflammatory processes is still not fully understood. In this study, the situation of a desialylated glycocalyx in vivo was mimicked by using a mouse heterozygous for the bifunctional enzyme glucosamine-2-epimerase/N-acetylmannosamine kinase (GNE; GNE+/-- mice). It was shown that gne transcription was reduced in the brain of young and old GNE+/-- mice and a reduced sialylation status was confirmed. In accordance with the in vitro data, an increased age-dependent neuronal loss was found in different brain regions of GNE+/-- mice compared to their wildtype littermates. Histological staining indicated morphological changes in microglia but not in astrocytes. Furthermore, only very minor inflammatory changes were observed in the transcriptome data of the brain pointing towards a homeostatic removal of neurons in GNE+/-- mice by microglia. Based on the in vitro studies, the GNE+/-- mice were crossbred with mice deficient for the complement component 3 (C3), the central player of the complement cascade, to confirm the involvement of the complement system. The C3-deficiency was able to rescue the neuronal loss in the GNE+/-- mice. Thus, this study successfully showed that the complement system is involved in microglial removal of neurons in vivo. The in vivo data demonstrate the importance of microglial sensing of small alterations in the glycocalyx. Sialic acids seem to play an essential role in maintaining brain homeostasis and might also be in involved in synaptic plasticity. However, oxidative stress or aging can lead to a decrease of sialic acids that then might lead to unwanted reactivation of developmental synaptic pruning and consequently to the loss of neurons in the brain. Thus, targeting the neuronal glycocalyx could be a beneficial therapy in age-dependent neuronal loss and neurodegenerative diseases.Komplement-vermittelter Verlust der Nervenzellen durch Sialinsäure-Veränderungen der GlykokalyxIm Alter nimmt die Häufigkeit an neurodegenerativen Erkrankungen zu, die mit einem generellen oder zelltypspezifischen Abbau von Nervenzellen einhergehen. Mikroglia, die Gehirnmakrophagen, stehen im ständigen Kontakt mit Nervenzellen, um kleinste Veränderungen wahrnehmen zu können. Dies geschieht über die zelluläre Glykokalyx, ein Geflecht aus verschiedenen Zuckern mit Sialinsäuren als terminaler Zucker. In der vorliegenden Studie wurde der Einfluss einer veränderten Glykokalyx im Gehirn in vivo untersucht. In vitro-Experimente zeigten bereits, dass die Entfernung der Sialinsäuren von der neuronalen Glykokalyx zur Komplementrezeptor 3-vermittelten Phagozytose der Nervenzellen durch Mikroglia/Makrophagen führt. Dieser Mechanismus wurde nun erfolgreich in ein Mausmodell übertragen. Als Modell wurde eine Maus verwendet, die heterozygot für das bifunktionelle Enzym UDP-N-Acetylglucosamin-2-Epimerase/N-Acetylmannosaminkinase (GNE+/--Maus) ist und dadurch eine niedrigere Sialylierung aufweist. Diese Mäuse zeigten einen Verlust von Nervenzellen in verschiedenen Gehirnregionen, der sich mit dem Alter weiter verstärkte. Parallel dazu wurde gezeigt, dass vor allem die langkettigen Polysialinsäuren reduziert waren. Trotz kontinuierlichem Nervenzellabbau konnten keine Entzündungsreaktionen im Gehirn festgestellt werden. Sowohl eine Transkriptom-Analyse, als auch eine Astrozyten- und Mikrogliaanalyse im Gehirn zeigten keine großen Auffälligkeiten. Lediglich die stärkere Exprimierung eines Mikroglia-/Makrophagenmarkers deutete auf eine erhöhte Mikroglia-Aktivität hin und lässt auf eine homöostatische Phagozytose schließen. Wichtige Erkenntnisse brachte die Kreuzung der GNE+/--Maus mit einer Komplementfaktor C3-defizienten Maus. Durch die vollständige Inhibierung des Komplementsystems konnte der Nervenzellabbau selbst bei alten GNE+/--Mäusen verhindert und dadurch die Involvierung des Komplementsystems auch in vivo nachgewiesen werden. Somit zeigt die vorliegende Arbeit, dass Sialinsäuren auch im komplexen Organismus eine zentrale Funktion in der Mikroglia-Nervenzell-Kommunikation einnehmen. Eine reduzierte Sialylierung führt zu einer Komplement-vermittelten Phagozytose der Nervenzellen durch Mikroglia. Das untersuchte Mausmodell, sowie die daraus gewonnenen Erkenntnisse bilden eine sehr gute Grundlage um den altersabhängigen Nervenzellverlust weiter zu untersuchen und geeignete Therapieansätze zur Vermeidung von neurodegenerativen Erkrankungen zu entwickeln

Cavity Quantum Electrodynamics with a Rydberg blocked atomic ensemble

We propose to implement the Jaynes-Cummings model by coupling a few-micrometer large atomic ensemble to a quantized cavity mode and classical laser fields. A two-photon transition resonantly couples the single-atom ground state |g> to a Rydberg state |e> via a non-resonant intermediate state |i>, but due to the interaction between Rydberg atoms only a single atom can be resonantly excited in the ensemble. This restricts the state space of the ensemble to the collective ground state |G> and the collectively excited state |E> with a single Rydberg excitation distributed evenly on all atoms. The collectively enhanced coupling of all atoms to the cavity field with coherent coupling strengths which are much larger than the decay rates in the system leads to the strong coupling regime of the resulting effective Jaynes-Cummings model. We use numerical simulations to show that the cavity transmission can be used to reveal detailed properties of the Jaynes-Cummings ladder of excited states, and that the atomic nonlinearity gives rise to highly non-trivial photon emission from the cavity. Finally, we suggest that the absence of interactions between remote Rydberg atoms may, due to a combinatorial effect, induce a cavity-assisted excitation blockade whose range is larger than the typical Rydberg dipole-dipole interaction length.Comment: 9 pages, 6 figure

The Effects of Mergers: An International Comparison

This paper analyzes the effects of mergers around the world over the past 15 years. We utilize a large panel of data on mergers to test several hypotheses about mergers. The effects of the mergers are examined by comparing the performance of the merging firms with control groups of nonmerging firms. The comparisons are made on profitability and sales. The results show that mergers on average do result in significant increases in profits, but reduce the sales of the merging firms. Interestingly, these post merger patterns look similar across countries. We also did not find dramatic differences between mergers in the manufacturing and the service sectors, and between domestic and cross-border mergers. Conglomerate mergers decrease sales more than horizontal mergers. By separating mergers into those that increase profits and those that reduce them and by then examining the patterns of sales changes following the mergers, we determine the effects of mergers on efficiency and market power. Our results suggest that those mergers that decrease profits and efficiency account for a large proportion. However, we can also identify mergers that increase profits by either increasing market power or by increasing efficiency. The first conclusion seems to be a more likely explanation for large companies, whereas the latter is likely to be true for small firms. ZUSAMMENFASSUNG - (Die Effekte von Fusionen: Ein internationaler Vergleich) Dieser Artikel analysiert die Effekte von Fusionen, die weltweit über die letzten 15 Jahre stattgefunden haben. Wir vergleichen die Gewinn- und Umsatzentwicklung von fusionierenden Firmen mit der Entwicklung von nicht-fusionierenden Firmen. Die Resultate zeigen, dass Fusionen im Durchschnitt zu signifikant höheren Profiten führen, aber dass die Umsätze im Vergleich zur Kontrollgruppe zurückbleiben. Interessanterweise sind diese Effekte bei Vergleichen zwischen den verschiedenen Ländern, bei einem Vergleich zwischen Industriesektor und Dienstleistungssektor bzw. zwischen nationalen und grenzüberschreitenden Fusionen ziemlich ähnlich. Konglomerate Fusionen reduzieren die Umsätze mehr als horizontale Fusionen. Um die Effekte der Fusionen auf die Marktmacht bzw. die Effizienz zu analysieren, teilen wir zuerst die Fusionen in gewinnsteigernde und gewinnreduzierende Fusionen, um dann die Umsatzentwicklung zu betrachten. Unsere Resultate zeigen, dass ein großer Prozentsatz der Fusionen die Gewinne und die Effizienz reduzieren. Wir können jedoch auch Fusionen identifizieren, die die Gewinne entweder durch Marktmacht- oder Effizienzsteigerungen erhöhen. Die erste Erklärung ist wahrscheinlicher für große Firmen, die zweite für kleine Firmen.Mergers, Acquisitions, International Comparison

A Flattening Approach for Attributed Type Graphs with Inheritance in Algebraic Graph Transformation

The algebraic graph transformation approach was initiated in 1973 and supports the rule-based modification of graphs based on pushout constructions. The vertex and edge types used within the rules (or productions) as well as possible inheritance relationships defined between them are specified in the type graph. However, the termination proof can only be accomplished for graph transformation systems without inheritance relationships. Thus, all graph transformation systems with inheritance relationships in the type graph must be flattened. To this end, the algebraic graph transformation approach provides a formal description for how to flatten the type graph as well as a definition of abstract and concrete productions. In this paper, we will extend the definitions to also consider vertices in negative application conditions with finer node types and positive application conditions. Furthermore, we will prove the semantic equivalence of the original and the flattened graph transformation system. The whole flattening algorithm is then implemented in a prototype which supports an abstract or concrete flattening of a given graph transformation system. The prototype is finally evaluated within a case study

Flowcytometric assessment of fetomaternal hemorrhage during external cephalic version at term

External cephalic version (ECV) at term is a safe procedure and reduces the incidence of cesarean sections for breech presentation. One of the known complications, however, is an ECV-related disruption of the placental barrier and a subsequent transfusion of fetal blood into maternal circulation. While the incidence of ECV-related fetomaternal hemorrhage (FMH) has been determined recently in a large trial using a manual Kleihauer-Betke test (KBT), questions remain on the amount of ECV-related FMH. KBT, which detects fetal red blood cells (RBC) on the basis of acidic resistance of fetal hemoglobin (HbF), is known to be a sensitive test, yet prone to procedural errors limiting its accuracy in quantifying FMH. In this study we investigated 50 patients for FMH before and after ECV, using a dual-color flow cytometric test kit with a lower limit of quantification of 0.05% fetal RBC in maternal peripheral blood. Three patients had a quantifiable increase of fetal RBC detected after ECV (0.06%; 0.08%; 0.1%). None of these subtle increments was predictable by ECV-related clinical parameters or translated into fetal compromise. Using a sensitive and accurate flow cytometric test method, our data provide further assurance to mothers on the safety of ECV at term

Competition in the economic crisis: Analysis of procurement auctions

We study the effects of the recent economic crisis on firms' bidding behavior and markups in sealed bid auctions. Using data from Austrian construction procurements, we estimate bidders' construction costs within a private value auction model. We find that markups of all bids submitted decrease by 1.5 percentage points in the recent economic crisis, markups of winning bids decrease by 3.3 percentage points. We also find that without the government stimulus package this decrease would have been larger. These two pieces of evidence point to pro-cyclical markups. (authors' abstract

Behaviour of adipose-derived canine mesenchymal stem cells after superparamagnetic iron oxide nanoparticles labelling for magnetic resonance imaging

Background: Therapy with mesenchymal stem cells (MSCs) has been reported to provide beneficial effects in the treatment of neurological and orthopaedic disorders in dogs. The exact mechanism of action is poorly understood. Magnetic resonance imaging (MRI) gives the opportunity to observe MSCs after clinical administration. To visualise MSCs with the help of MRI, labelling with an MRI contrast agent is necessary. However, it must be clarified whether there is any negative influence on cell function and viability after labelling prior to clinical administration. Results: For the purpose of the study, seven samples with canine adipose-derived stem cells were incubated with superparamagnetic iron oxide nanoparticles (SPIO: 319.2 µg/mL Fe) for 24 h. The internalisation of the iron particles occurred via endocytosis. SPIO particles were localized as free clusters in the cytoplasm or within lysosomes depending on the time of investigation. The efficiency of the labelling was investigated using Prussian blue staining and MACS assay. After 3 weeks the percentage of SPIO labelled canine stem cells decreased. Phalloidin staining showed no negative effect on the cytoskeleton. Labelled cells underwent osteogenic and adipogenic differentiation. Chondrogenic differentiation occurred to a lesser extent compared with a control sample. MTT-Test and wound healing assay showed no influence of labelling on the proliferation. The duration of SPIO labelling was assessed using a 1 Tesla clinical MRI scanner and T2 weighted turbo spin echo and T2 weighted gradient echo MRI sequences 1, 2 and 3 weeks after labelling. The hypointensity caused by SPIO lasted for 3 weeks in both sequences. Conclusions: An Endorem labelling concentration of 319.2 µg/mL Fe (448 µg/mL SPIO) had no adverse effects on the viability of canine ASCs. Therefore, this contrast agent could be used as a model for iron oxide labelling agents. However, the tracking ability in vivo has to be evaluated in further studies

Nitrogen Budgets and Soil Nitrogen Stocks of Organic and Conventional Cropping Systems: Trade-Off between Efficiency and Sustainability of Nitrogen Use

Organic and conventional cropping systems differ in the nature and amounts of nitrogen (N) inputs, which may affect efficiency and sustainability of N use. In the DOK (bio-Dynamic, bio-Organic, Konventionell) field experiment, organic and conventional cropping systems have been compared since 1978 at two fertilization levels. Nitrogen inputs via manure and/or mineral fertilizers, and N exports from plots with harvested products have throughout been recorded. For all treatments, N outputs with harvests have exceeded the inputs with fertilizers. Over the past years, symbiotic N2 fixation by soybean and clover grown in the trial has additionally been assessed, indicating average annual inputs of about 100 kg ha-1 yr-1 of N fixed from the atmosphere. Soil surface budgets opposing N inputs via fertilization, symbiotic fixation, seeds and deposition to N outputs via harvested products have been computed at the plot level for the duration from 1985 to 2012. The resulting balances range from negative values of about -20 kg N ha-1 yr-1 (where outputs exceed the sum of said N inputs) to surpluses of about +50 kg N ha-1 yr-1. The budget based N use efficiency (NUE; N output via harvested products divided by sum of N inputs) in the case of negative balances suggests irrationally high NUE (>100%), while positive balances are related to lower NUE for treatments with inputs exceeding outputs. Negative balances, however, indicate soil N mining, while surpluses point to a risk of N losses, and/or N accumulation in the soil. Estimation of soil N stock changes based on yearly total N concentration measurements in the topsoil layer is currently ongoing. Preliminary results suggest that soil N stocks in the topsoil decreased under all treatments more than expected from the N balance, and that positive N balances are needed to maintain topsoil N stocks. An increase in soil N concentration was observed in none of the treatments. In conclusion, the results indicate an efficiency-sustainability trade-off. Treatments with a higher NUE lose more soil stock N than those with a lower NUE. Treatments with lower NUE indicate higher N losses from the studied crop-topsoil system. Sustainable soil N management in addition to organic fertilizer inputs might at this site require reduced soil tillage. The significance of N contained in deeper soil layers, and deep rooting crops in recovering leached N should as well be investigated