Breaks in interstellar spectra of positrons and electrons derived from time-dependent AMS data

Until fairly recently, it was widely accepted that local cosmic ray spectra were largely featureless power laws, containing limited information on their acceleration and transport. This viewpoint is currently being revised in the light of evidence for a variety of spectral breaks in the fluxes of cosmic ray nuclei. Here, we focus on cosmic ray electrons and positrons which at the highest energies must be of local origin due to strong radiative losses. We consider a pure diffusion model for their Galactic transport and determine its free parameters by fitting data in a wide energy range: measurements of the interstellar spectrum by Voyager at MeV energies, radio synchrotron data (sensitive to GeV electrons and positrons) and local observations by AMS up to ~ 1 TeV. For the first time, we also model the time-dependent fluxes of cosmic ray electrons and positrons at GeV energies recently presented by AMS, treating solar modulation in a simple extension of the widely used force-field approximation. We are able to reproduce all the available measurements to date. Our model of the interstellar spectrum of cosmic ray electrons and positrons requires the presence of a number of spectral breaks, both in the source spectra and the diffusion coefficients. While we remain agnostic as to the origin of these spectral breaks, their presence will inform future models of the microphysics of cosmic ray acceleration and transport.Comment: 19 pages, 9 figures; submitted to PR

The Description of the Evolution of Deuterated Water in a Multi-Stage Model of the Solar Nebula

Die Entstehung von Leben ist eng mit dem Vorhandensein von Wasser und präbiotischen Molekülen verknüpft. Da solche Verbindungen schon in den frühesten Phasen der Sternentstehung nachgewiesen wurden, stellt sich sofort die Frage nach der Historie dieser Vorkommen und deren Verfügbarkeit während der Entstehung der terrestrischen Planeten. Wird von der Solaren Nebel Hypothese ausgegangen, bilden sich Planetensysteme aus den Protoplanetaren Scheiben, die beim Kollaps von metastabilen, hydrostatischen Wolkenkernen entstehen können. Da insbesondere der relative Anteil von deuteriertem Wasser Hinweise auf die Historie des Wassertransports geben kann, wird dessen Verteilung im Rahmen der vorliegenden Arbeit über die zeitliche Entwicklung der Phasen des Solaren Nebels untersucht, und die Ergebnisse anschließend mit Messungen an Kometen und Sternentstehungsregionen verglichen. Die einzelnen Modelle basieren auf einem Kernmodell mit Bonnor-Ebert Profil, einem semi-analytischen, adiabatischen Kollapsmodell und einem Modell für die optisch dichte T-Tauri Scheibenphase. Dabei liegt der Fokus auf der Integration der einzelnen Modelle hin zu einem Ab-initio-Modell, in dem jede Phase von der vorherigen initialisiert wird. Es zeigt sich, dass die Entstehung von Wasser während der Wolkenphase nur sehr wenig von externen Parametern wie Strahlung und Staubbewegung in der Einhüllenden beeinflusst wird, und es relativ gleichmäßig in Form von eisummanteltem Staub über den Wolkenkern verteilt ist. Die Deuterierung des Wassers ist zu dieser Zeit in den inneren Regionen des Kerns höher und weist ein D/H Verhältnis von maximal 2,2% auf. Am Ende des Kollaps bildet sich bei ca. 1,4 AU eine sog. "Hot Corino" Zone aus, in der die Evaporation des Wassereises vom Staubmantel einsetzt. Aufgrund des rein adiabatischen Ansatzes für den Kollaps liegt zu Beginn der Scheibenphase ein sehr geringer Temperaturgradient vor, wodurch es zu Abweichungen von der erwarteten MMSN Scheibenstruktur kommt. Die einsetzenden Neutral-Neutral Reaktionen können das D/H Verhältnis daher noch nicht signifikant reduzieren, sodass am Ende des Kollaps im Bereich der sich bildenden Scheibe ein konstantes D/H Verhältnis von 2,5% vorliegt. Die kontinuierliche Initialisierung der chemischen Konzentrationen führt beim Übergang zur Scheibe zu starken Einschwingvorgängen und erfordert zukünftig die Einbindung eines zwischengeschalteten Modells für den Aufbau der vertikalen Struktur.Many definitions of habitability rest on the availability of liquid water, but it is still an open question where planetary water actually comes from. Recently it has been confirmed that it already exists within grand molecular clouds, which are nurseries for stellar formations, along with certain prebiotic molecules. Within the Solar Nebula hypothesis the metastable hydrostatic cores of these clouds collapse while building up a disk around their equatorial plane of rotation to redistribute their angular momentum. Based on this temporal evolution this work seeks to model the transport and chemical evolution of the matter accreted by the protostar during the three stages of the Solar Nebula in an ab-initio approach, so that every stage is initialized by the physical and chemical parameters of the former. The individual models are a hydrostatic cloud core, a semianalytic adiabatic collapse and a disk model, including detailed dust convection. The chemistry is treated in a Lagrangian approach by combining the before mentioned models with a gas-grain chemistry model. The main focus is on the distribution of water and its deuterated counterparts since the D/H ratio can give important clues about the origin and history of cometary and planetary water reservoirs. The results suggest that water is a robust phenomenon within the cloud stage and is relatively insensitive to variations in the external radiation and dust migration in its envelope. The highest fraction of deuterated water is located in the deeply embedded core region with a D/H value of at most 2,2%. Meanwhile, the overall water concentration is found to be almost constant along the radial extent of the core, mainly carried by ice coated grains. Towards the end of the collapse of the cloud core a "hot corino" zone builds up with a diameter of less than 1,4 astronomical units. The beginning neutral-neutral reactions in this zone can not jet change the deuteration significantly, leading to a radially constant value of D/H approx. 2,5% in the disk build up region. Due to the adiabatic nature of the collapse, the resulting disk has a very low temperature gradient which also leads to other deviations from the expected MMSN structure. The continuous initialization of the chemical disk composition has been hindered by the absence of a vertical representation in the collapse phase. In the future this can be improved by adding an intermediate thick disk model

Height Simulation in a Virtual Reality CAVE System: Validity of Fear Responses and Effects of an Immersion Manipulation

Acrophobia is characterized by intense fear in height situations. Virtual reality (VR) can be used to trigger such phobic fear, and VR exposure therapy (VRET) has proven effective for treatment of phobias, although it remains important to further elucidate factors that modulate and mediate the fear responses triggered in VR. The present study assessed verbal and behavioral fear responses triggered by a height simulation in a 5-sided cave automatic virtual environment (CAVE) with visual and acoustic simulation and further investigated how fear responses are modulated by immersion, i.e., an additional wind simulation, and presence, i.e., the feeling to be present in the VE. Results revealed a high validity for the CAVE and VE in provoking height related self-reported fear and avoidance behavior in accordance with a trait measure of acrophobic fear. Increasing immersion significantly increased fear responses in high height anxious (HHA) participants, but did not affect presence. Nevertheless, presence was found to be an important predictor of fear responses. We conclude that a CAVE system can be used to elicit valid fear responses, which might be further enhanced by immersion manipulations independent from presence. These results may help to improve VRET efficacy and its transfer to real situations

Comparison between B·R·A·H·M·S PCT direct, a new sensitive point-of-care testing device for rapid quantification of procalcitonin in emergency department patients and established reference methods - a prospective multinational trial

Background: Procalcitonin (PCT) is increasingly being used for the diagnostic and prognostic work up of patients with suspected infections in the emergency department (ED). Recently, B·R·A·H·M·S PCT direct, the first high sensitive point-of-care test (POCT), has been developed for fast PCT measurement on capillary or venous blood samples. Methods: This is a prospective, international comparison study conducted in three European EDs. Consecutive patients with suspicion of bacterial infection were included. Duplicate determination of PCT was performed in capillary (fingertip) and venous whole blood (EDTA), and compared to the reference method. The diagnostic accuracy was evaluated by correlation and concordance analyses. Results: Three hundred and three patients were included over a 6-month period (60.4% male, median age 65.2 years). The correlation between capillary or venous whole blood and the reference method was excellent: r2=0.96 and 0.97, sensitivity 88.1% and 93.0%, specificity 96.5% and 96.8%, concordance 93% and 95%, respectively at a 0.25 μg/L threshold. No significant bias was observed (-0.04 and -0.02 for capillary and venous whole blood) although there were 6.8% and 5.1% outliers, respectively. B·R·A·H·M·S PCT direct had a shorter time to result as compared to the reference method (25 vs. 144 min, difference 119 min, 95% CI 110-134 min, p<0.0001). Conclusions: This study found a high diagnostic accuracy and a faster time to result of B·R·A·H·M·S PCT direct in the ED setting, allowing shortening time to therapy and a more wide-spread use of PCT

Molecular mechanisms of cell death: recommendations of the Nomenclature Committee on Cell Death 2018.

Over the past decade, the Nomenclature Committee on Cell Death (NCCD) has formulated guidelines for the definition and interpretation of cell death from morphological, biochemical, and functional perspectives. Since the field continues to expand and novel mechanisms that orchestrate multiple cell death pathways are unveiled, we propose an updated classification of cell death subroutines focusing on mechanistic and essential (as opposed to correlative and dispensable) aspects of the process. As we provide molecularly oriented definitions of terms including intrinsic apoptosis, extrinsic apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, parthanatos, entotic cell death, NETotic cell death, lysosome-dependent cell death, autophagy-dependent cell death, immunogenic cell death, cellular senescence, and mitotic catastrophe, we discuss the utility of neologisms that refer to highly specialized instances of these processes. The mission of the NCCD is to provide a widely accepted nomenclature on cell death in support of the continued development of the field

Die Beschreibung der Entwicklung von deuteriertem Wasser mithilfe eines Multi-Zustandsmodells des Solaren Nebels

Many definitions of habitability rest on the availability of liquid water, but it is still an open question where planetary water actually comes from. Recently it has been con- firmed that it already exists within grand molecular clouds, which are nurseries for stellar formations, along with certain prebiotic molecules. Within the Solar Nebula hypothesis the metastable hydrostatic cores of these clouds collapse while building up a disk around their equatorial plane of rotation to redistribute their angular momentum. Based on this temporal evolution this work seeks to model the transport and chemical evolution of the matter accreted by the protostar during the three stages of the Solar Nebula in an ab-initio approach, so that every stage is initialized by the physical and chemical Parameters of the former. The individual models are a hydrostatic cloud core, a semianalytic adiabatic collapse and a disk model, including detailed dust convection. The chemistry is treated in a Lagrangian approach by combining the before mentioned models with a gas-grain chemistry model. The main focus is on the distribution of water and ist deuterated counterparts since the D=H ratio can give important clues about the origin and history of cometary and planetary water reservoirs. The results suggest that water is a robust phenomenon within the cloud stage and is relatively insensitive to variations in the external radiation and dust migration in its envelope. The highest fraction of deuterated water is located in the deeply embedded core region with a D/H value of at most 2.2%. Meanwhile, the overall water concentration is found to be almost constant along the radial extent of the core, mainly carried by ice coated grains. Towards the end of the collapse of the cloud core a \hot corino" zone builds up with a diameter of less than 1.4 astronomical units. The beginning neutral-neutral reactions in this Zone can not jet change the deuteration significantly, leading to a radially constant value of D/H ~ 2.5% in the disk build up region. Due to the adiabatic nature of the collapse, the resulting disk has a very low temperature gradient which also leads to other deviations from the expected MMSN structure. The continuous initialization of the chemical disk composition has been hindered by the absence of a vertical representation in the collapse phase. In the future this can be improved by adding an intermediate thick disk model

Simulating the D/H ratio of water formed in the early solar nebula

Our solar system originated from a protoplanetary disk about 4.6 billion years ago. We simulate the formation of this disk by a three-stage model of the solar nebula (SN) which describes the hydrodynamic and chemical evolution of a cold cloud core consisting of gas and one mass percent dust. Considering the first two stages of this SN-model we have studied the formation and deuteration of water, which is an important precondition of life. During the quasi-stationary stage of the cloud core, corresponding to the first SN stage, water has been formed on the surface of dust grains by the hydrogenation of oxygen. The gas and dust temperatures, which differ at the outer boundary of the core, are nearly 14 K and reach 9 K in its center. Therefore an icy mantle forms on the dust grains in less than 105 years and changes slowly afterwards. Because of the large abundance of hydrogen and a carbon to oxygen (C/O) ratio of 0.44 the major component of this mantle is water ice. We found that the water produced in the gas phase amounts to less than 20 ppm of the water formed on dust grains. In both phases, the deuterium enrichment δD (‰) relative to the Standard Mean Ocean Water varies at 1 AU from 15,050 to 63,100‰ (or a D/H ratio from 2 to 0.5%) and indicates the low formation temperature of water molecules. In the second stage of our SN-model, the collapse of the cold cloud core is simulated using a semi-analytical solution of the magneto-hydrodynamic equations. Due to relatively high temperatures around the center (10^(2-3) K), this range is identified with the hot corino observed in regions of low mass star formation in our galaxy. There, the icy mantles of the grains vanish due to desorption of water molecules from their surfaces. As a result the water to hydrogen ratio in the gas phase increases to 10^(-5)-10^(-4). Since this water was formed in a cold region and a collision related destruction of water molecules (occurring at ~10^5 K) can be neglected everywhere except for the protostellar source in the core center (< 10^(-2) AU), the deuterium enrichment in the outer hot corino (1 AU) reaches δD of 2,210‰ (or D/H of 0.1%) at the end of the main collapse phase. Different reasons for this relatively high value are discussed

Two Different Sources of Water for the Early Solar Nebula

Water is essential for life. This is a trivial fact but has profound implications since the forming of life on the early Earth required water. The sources of water and the related amount of delivery depend not only on the conditions on the early Earth itself but also on the evolutionary history of the solar system. Thus we ask where and when water formed in the solar nebula—the precursor of the solar system. In this paper we explore the chemical mechanics for water formation and its expected abundance. This is achieved by studying the parental cloud core of the solar nebula and its gravitational collapse. We have identified two different sources of water for the region of Earth’s accretion. The first being the sublimation of the icy mantles of dust grains formed in the parental cloud. The second source is located in the inner region of the collapsing cloud core - the so-called hot corino with a temperature of several hundred Kelvin. There, water is produced efficiently in the gas phase by reactions between neutral molecules. Additionally, we analyse the dependence of the production of water on the initial abundance ratio between carbon and oxygen

Two Different Sources of Water in Earth’s Accretion Zone of the Solar Nebula

The origin of water and the related significance for the early Earth depend on the conditions in the different stages of the solar nebula and the later solar system. With our model we simulate the chemical and hydrodynamic processes of the solar nebula. For that purpose we explicitly consider the evolution of the parental cloud core, its gravitational collapse, and the resulting turbulent disk. As a consequence of the low temperature ( 8 K) in the center of the cloud core thick ice layers are formed on the dust grains. The collapse is simulated using a new semi-analytic multi-zone solution of the hydrodynamic equations which is valid for spherical symmetry. Initially, the density distribution of the inner zone represents a central clump from which the proto-sun and later the T Tauri Sun form. The two outer zones evolve into a disk and a thin but spatially extended envelope. The disk stage is described by a stationary model and considers a weakly coupled gas and dust phase. We have identified two different sources of water for the region of Earth’s accretion. The first source is located in the inner region of the collapsing cloud core where the temperature could reach about 500 K. There, water was produced efficiently by gas phase reactions between neutral molecules. The second source is related to icy mantles of dust grains formed in the cloud core and disk stage. In the course of disk evolution cooling caused an enrichment of the dust phase with water ice beyond the snowline which moved inwards, i.e. into the Earth accretion zone. In addition we present results how water formation is related to the initial abundance ratio between carbon and oxygen in the cloud. This research has been supported by the Helmholtz Association through the research alliance “Planetary Evolution and Life“