Disk formation in the collapse of supramassive neutron stars

Short gamma-ray bursts (sGRBs) show a large diversity in their properties. This suggests that the observed phenomenon can be caused by different "central engines" or that the engine produces a variety of outcomes depending on its parameters, or possibly both. The most popular engine scenario, the merger of two neutron stars, has received support from the recent Fermi and INTEGRAL detection of a burst of gamma rays (GRB170817A) following the neutron star merger GW170817, but at the moment it is not clear how peculiar this event potentially was. Several sGRBs engine models involve the collapse of a supramassive neutron star that produces a black hole plus an accretion disk. We study this scenario for a variety of equations of states both via angular momentum considerations based on equilibrium models and via fully dynamical Numerical Relativity simulations. We obtain a broader range of disk forming configurations than earlier studies but we agree with the latter that none of these configurations is likely to produce a phenomenon that would be classified as an sGRB.Comment: accepted by MNRA

Very cold and massive cores near ISOSS J18364-0221: Implications for the initial conditions of high-mass star-formation

We report the discovery of two very cold and massive molecular cloud cores in the region ISOSS J18364-0221. The object has been identified by a systematic search for very early evolutionary stages of high-mass stars using the 170 micron ISOPHOT Serendipity Survey (ISOSS). Submm continuum and molecular line measurements reveal two compact cores within this region. The first core has a temperature of 16.5 K, shows signs of ongoing infall and outflows, has no NIR or MIR counterpart and is massive enough (M ~ 75 M_sun) to form at least one O star with an associated cluster. It is therefore considered a candidate for a genuine high-mass protostar and a high-mass analog to the Class 0 objects. The second core has an average gas and dust temperature of only ~ 12 K and a mass of M ~ 280 M_sun. Its temperature and level of turbulence are below the values found for massive cores so far and are suggested to represent the initial conditions from which high-mass star formation occurs.Comment: 9 pages, 6 figures, accepted for publication in the Astrophysical Journa

Molecular signatures defining proprioceptor muscle-type identity

Proprioception, the sense of body position in space, is critical for generating coordinated movements and reflexive actions. Proprioceptive sensory neurons (pSN) reside in the dorsal root ganglia and constantly monitor muscle stretch and tension with their mechanoreceptive organs (muscle spindles and Golgi-tendon organs) and relay this information to central circuits that generate coordinated motor actions. In particular, group Ia pSN afferents (muscle spindle) provide direct sensory feedback to motor neurons controlling the activity of the same muscle while avoiding motor neurons of antagonistic muscle groups. This precise connectivity pattern represents the basis of the stretch reflex arc and suggests the existence of proprioceptor subtypes defined by the muscle they innervate. However, molecular programs controlling critical aspects of pSN subtype identities, such as the central and peripheral connectivity, are mainly unknown. In this study, we devised a single-cell transcriptomic approach that takes advantage of the topographic organization of the pSN system to reveal molecular features of cardinal proprioceptor subtypes defined by their connectivity to limb, back, and abdominal muscles. First, we identified and validated molecular signatures for each pSN muscle-type population. Second, we found that molecular programs defining these identities are acquired early in development and maintained until early postnatal stages. Last, we discovered distinct expression patterns of axon guidance molecules of the ephrin-A/EphA family that distingush axial- and limb-pSN. In particular, we found that the absence of ephrin-A5 affects the peripheral connectivity of limb-pSN with specific hindlimb muscles, thus implying an important role for ephrin-A signaling in controlling the assembly of sensorimotor circuits. Altogether, this work reveals the molecular foundation of pSN muscle-type identity and paves the way for studying the development and function of muscle-specific sensory feedback circuits

Influence of Internal Climate Variability on Estuarine Sediment Dynamics

Mini-Symposium: Impacts of Climate Chang

The potential of dust detection by means of µXRF scanning in Eifel maar lake sediments

Mittels kontinuierlicher und hochauflösender μXRF-Geochemieanalysen wird die Variabilität äolischer Sedimente der letzten 60.000 Jahre rekonstruiert. Dazu werden zwei Sedimentbohrkerne jeweils aus einem Maarsee und einem Trockenenmaar (Eifel, Deutschland) untersucht. Beide Kerne umfassen das letzte Glazial, einschließlich des MIS-3, des LGM und MIS-2, Transition I als auch das Holozän. Die energiedispersive RFA-Messungen der Eagle III μXRF wird direkt an Harz imprägnierten Proben angewendet. Diese sogenannten Tränklinge bilden die Grundlage für die Herstellung von petrographischen Dünnschliffen und somit können die Messergebnisse direkt mit einer Mikrofaziesanalyse verglichen werden. Anhand eines Sedimentkerns wird gezeigt, dass eine Quantifizierung der μXRF-Ergebnisse mittels der undamentalparametermethode geeignete ist. Eine Überprüfung der Ergebnisse findet dabei mit wellenlängen-dispersiven RFA-Messungen an diskreten Proben statt. Die Ergebnisse zeigen, dass sich jedes einzelne Maar in der lithologischen Zusammensetzung und damit auch geochemisch unterscheidet. Deshalb wird auf die grundlegenden Prozesse der Elementdeposition in die Seen eingegangen, die mit der Ablagerung von Sedimenten, der Variabilität der chemischen Verwitterung oder der Wasserzirkulation in Zusammenhang stehen. Mittels Hauptkomponentenanalysen standardisierter Variablen ist darüber hinaus die objektive Ableitung eines äolischen Sedimentsignals möglich. Es wird gezeigt, dass dieser Ansatz verlässliche Ergebnisse für alle untersuchten Zeitabschnitte liefert, solange für die Interpretation weitere Kenntnisse über die Lithologie und Paläoökologie zur Verfügung stehen. Das auffälligste Element zur Charakterisierung von Staub ist in beiden untersuchten Kernen Kalzium. Die höchsten Werte (>5 Gew.-%) werden während vollglazialer Bedingungen erreicht. Kalzium hat einen wesentlichen Einfluss auf den Staubfaktor der Hauptkomponentenanalyse. Eine zusätzliche Kombination der Kalziumgehalte mit dem Staubfaktor der Hauptkomponentenanalyse sowie Grauwertmessungen verbessert den Nachweis äolischen Staubs in laminierten Seesedimenten zusätzlich. In beiden Kernen konnten Sedimente mit erhöhten Staubkonzentrationen geochemisch nachgewiesen werden: Während des MIS-3 sind das vor allem das größte Heinrich-Ereignis H4 sowie der Anstieg des atmosphärischen Staubgehalts während der Wiedervereisung der Inlandsgletscher. Weiterhin ist das gesamte MIS-2 einschließlich LGM und der Jüngeren Dryas von starker Staubdeposition charakterisiert. Eine erhöhte Staubkonzentration ist ebenfalls ab dem Subboreal nachgewiesen und wird als anthropogene Aktivität gedeutet.researc

Influence of fermentation temperature and duration on survival and biocontrol efficacy of Pseudomonas fluorescens Pf153 freeze‐dried cells

Aim: The aim of this paper was to determine whether the quality of formulated Pseudomonas fluorescens Pf153 can be influenced by changes in fermentation conditions. In this study, the influence of the fermentation temperature on the growth and its consequence on shelf life, viability and biocontrol efficacy of freeze-dried cells of P. fluorescens Pf153 was investigated. Methods and Results: Cells of P. fluorescens Pf153 were grown at 20 and 28°C in flasks and fermenter and harvested in the mid-log and the beginning of the stationary phase. The survival during storage of freeze-dried cells was tested at 25°C. Cells fermented at 20°C survived in storage better than those grown at 28°C, irrespective of the harvesting time. Compared to the untreated control, in in vitro tests Pf153 was in all production temperature/duration combinations significantly effective against all tested Botrytis cinerea strains. But no differences between temperature/duration combinations were found. In bioassay on detached Vicia faba leaves, it was found that young cells, when fermented at 28°C had a significant positive influence on the biocontrol efficacy. Conclusions: These results demonstrate that fermentation parameters have an influence on the performance and quality of a formulated product. Significance and Impact of the Study: Only limited numbers of biocontrol products based on antagonistic pseudomonads are on the market. This can be attributed to the lack of suitable formulated products with high numbers of viable cells and a good shelf life. Currently, only limited information on the influence of the fermentation on subsequent downstreaming process is available. Within this study, we focused on the influence of the two important parameters fermentation temperature and harvest time on survival, shelf life and biocontrol efficacy of P. fluorescens Pf153.Lincoln University http://dx.doi.org/10.13039/100007032Peer Reviewe