Stochastic Acceleration of Low Energy Electrons in Cold Plasmas

We investigate the possibility of stochastic acceleration of background low-energy electrons by turbulent plasma waves. We consider the resonant interaction of the charged particles with all branches of the transverse plasma waves propagating parallel to a uniform magnetic field. Numerical results and asymptotic analytic solutions valid at non-relativistic and ultra-relativistic energies are obtained for the acceleration and scattering times of electrons. These times have a strong dependence on plasma parameter alpha = Omega_pe / Omega_e (the ratio of electron plasma frequency to electron gyrofrequency) and on the spectral index of plasma turbulence. It is shown that particles with energies above certain critical value may interact with higher frequency electromagnetic plasma waves and this interaction is allowed only in plasmas with alpha < 1. We show that for non-relativistic and semi-relativistic electrons in low-alpha plasmas the ratio of the acceleration time to the scattering time can be less than unity for a wide range of energies. From this we conclude that the transport equation derived for cosmic rays which requires this ratio to be much larger than one is not applicable at these energies. An approximate "critical" value of particle energy above which the dynamics of charged particles may be described by this transport equation is determined as a function of plasma parameters. We propose new transport equation for the opposite limit (energies less than this critical value) when the acceleration rate is much faster than the pitch angle scattering rate. This equation is needed to describe the electron dynamics in plasmas with alpha <= 0.1.Comment: 22 pages, 13 figures, Latex, submitted to Astrophysical Journa

BICEPS: An improved characterization model for low- and intermediate-mass exoplanets

Context. The number of exoplanets with precise mass and radius measurements is constantly increasing thanks to novel ground- and space-based facilities such as HARPS, ESPRESSO, CHEOPS, and TESS. The accuracy and robustness of the planetary characterization largely depends on the quality of the data, but also requires a planetary structure model, capable of accurately modeling the interior and atmospheres of exoplanets over a large range of boundary conditions. Aims. Our goal is to provide an improved characterization model for planets with masses between 0.5 and 30 Earth masses, equilibrium temperatures below <2000 K, and a wide range of planetary compositions and physical phases. Methods. In this work, we present the Bayesian Interior Characterization of ExoPlanetS (BICEPS) model, which combines an adaptive Markov chain Monte Carlo sampling method with a state-of-the-art planetary structure model. BICEPS incorporates many recently developed equations of state suited for large ranges of pressures and temperatures, a description for solid and molten planetary cores and mantles, a gaseous envelope composed of hydrogen, helium, and water (with compositional gradients), and a non-gray atmospheric model. Results. We find that the usage of updated equations of state has a significant impact on the interior structure prediction. The impact varies, depending on the planetary composition. For dense rocky planets, BICEPS predicts radii a few percent different to prior internal structure models. For volatile rich planets, we find differences of 10% or even larger. When applying BICEPS to a particular exoplanet, TOI-130 b, we inferred a 25% larger water mass fraction and a 15% smaller core than previous models. Conclusions. The presented exoplanet characterization model is a robust method applicable over a large range of planetary masses, compositions, and thermal boundary conditions. We show the importance of implementing state-of-the-art equations of state for the encountered thermodynamic conditions of exoplanets. Hence, using BICEPS improves the predictive strength of the characterization process compared to previous methods.ISSN:0004-6361ISSN:1432-074

The formation of Jupiter by hybrid pebble-planetesimal accretion

The standard model for giant planet formation is based on the accretion of solids by a growing planetary embryo, followed by rapid gas accretion once the planet exceeds a so-called critical mass. The dominant size of the accreted solids (cm-size particles named pebbles or km to hundred km-size bodies named planetesimals) is, however, unknown. Recently, high-precision measurements of isotopes in meteorites provided evidence for the existence of two reservoirs in the early Solar System. These reservoirs remained separated from ~1 until ~ 3 Myr after the beginning of the Solar System's formation. This separation is interpreted as resulting from Jupiter growing and becoming a barrier for material transport. In this framework, Jupiter reached ~20 Earth masses within ~1 Myr and slowly grew to ~50 Earth masses in the subsequent 2 Myr before reaching its present-day mass. The evidence that Jupiter slowed down its growth after reaching 20 Earth masses for at least 2 Myr is puzzling because a planet of this mass is expected to trigger fast runaway gas accretion. Here, we use theoretical models to describe the conditions allowing for such a slow accretion and show that Jupiter grew in three distinct phases. First, rapid pebble accretion brought the major part of Jupiter's core mass. Second, slow planetesimal accretion provided the energy required to hinder runaway gas accretion during 2 Myr. Third, runaway gas accretion proceeded. Both pebbles and planetesimals therefore have an important role in Jupiter's formation.Comment: Published in Nature Astronomy on August 27, 201

Late Pleistocene human genome suggests a local origin for the first farmers of central Anatolia

Anatolia was home to some of the earliest farming communities. It has been long debated whether a migration of farming groups introduced agriculture to central Anatolia. Here, we report the first genome-wide data from a 15,000-year-old Anatolian hunter-gatherer and from seven Anatolian and Levantine early farmers. We find high genetic continuity (~80–90%) between the hunter-gatherers and early farmers of Anatolia and detect two distinct incoming ancestries: an early Iranian/Caucasus related one and a later one linked to the ancient Levant. Finally, we observe a genetic link between southern Europe and the Near East predating 15,000 years ago. Our results suggest a limited role of human migration in the emergence of agriculture in central Anatolia

Regionaler Klimaschutz in Zeiten der Krise? Eine vergleichende Untersuchung von zehn Landkreisen in vier Bundesländern

Das novellierte Klimaschutzgesetz von 2021 gilt als ein wesentlicher Schritt zur Erfüllung der nationalen Klimaschutzziele und als Zeichen einer stärkeren Verankerung des Klimaschutzes in der deutschen Politik. Auf regionaler Ebene, auf der viele Klimaschutzmaßnahmen umgesetzt werden, zeigt sich jedoch eine starke Fragmentierung hinsichtlich der Prioritäten, Politikinstrumente, Akteurkonstellationen und Ressourcen. Darüber hinaus gerät die Umsetzung von Klimaschutzmaßnahmen angesichts von Krisen - wie der Bewältigung der Covid-19-Pandemie oder der Energiekrise - zunehmend unter Druck. Es stellt sich daher die Frage: Unter welchen Bedingungen gelingt regionaler Klimaschutz in Krisenzeiten? Auf der Basis des Regional-Governance-Konzeptes und einer vergleichenden Analyse von zehn Landkreisen erklären wir Unterschiede in der subnationalen Klima-Governance. Für die Untersuchung der Landkreise wurden unterschiedliche ländlich geprägte Regionen ausgewählt, da diese bei Untersuchungen zu lokaler Klimapolitik häufig vernachlässigt werden. Basierend auf einer qualitativen Dokumentenanalyse in Verbindung mit Beobachtungen und Interviews mit Klimaschutzmanagerinnen und -managern identifizieren wir Faktoren für das Gelingen von Klimaschutzaktivität in Zeiten multipler Krisen. Wir argumentieren, dass strukturelle Faktoren in Krisenzeiten zentral für den Erfolg regionaler Klimaschutzmaßnahmen sind, da sie die Rahmenbedingungen für das Handeln von Akteuren bilden.The amended German Climate Protection Act of 2021 is seen as an essential step towards fulfilment national climate protection targets and as a sign of mainstreaming climate protection in German politics. However, at the regional level, where many climate protection measures are implemented, there is a strong fragmentation in terms of priorities, policy instruments, actor constellations and resources. Moreover, the implementation of climate protection measures is under increasing pressure in the face of crises, such as the management of the Covid 19 pandemic or the energy crisis. We therefore ask: Under what conditions does regional climate protection succeed in times of crisis? Drawing on the regional governance concept and a comparative analysis of ten German counties, we explain differences in subnational climate governance. For our study, very different, but always rural districts were selected, as the importance of rural regions is often neglected in the study of local climate policy. Based on a qualitative document analysis in combination with observations and interviews with climate protection managers, we identify factors for the success of climate protection activities in times of multiple crises. We argue that structural factors are central to the success of regional climate protection measures in times of crisis, as they provide the framework conditions for the actions of actors

Burying power: New insights into incipient leadership in the Late Pre-Pottery Neolithic from an outstanding burial at Baʻja, southern Jordan

In 2016, an extraordinary burial of a young adult individual was discovered at the Late Pre-Pottery Neolithic B (LPPNB, 7,500–6,900 BCE) settlement of Baʻja in southern Jordan. This burial has exceptional grave goods and an elaborate grave construction. It suggests discussing anew reconstructions of early Neolithic social structures. In this article, we will summarize former theories on the emergence of leadership and hierarchies and present a multivariate model according to which anthropological and archaeological data of the burial will be analyzed. In conclusion, we surmise that early Neolithic hierarchization in southern Jordan was based on corporate pathways to power rather than self-interested aggrandizers. However, some aspects of the burial point to regional exchange networks of prestige goods, a trait considered characteristic of network based leadership. In line with anthropological and sociological research, we argue that pathways to power should be considered as relational processes that can be understood only when comparing traits of the outstanding person to her/his social environment

Isotopic and DNA analyses reveal multiscale PPNB mobility and migration across Southeastern Anatolia and the Southern Levant

Growing reliance on animal and plant domestication in the Near East and beyond during the Pre-Pottery Neolithic B (PPNB) (the ninth to eighth millennium BC) has often been associated with a “revolutionary” social transformation from mobility toward more sedentary lifestyles. We are able to yield nuanced insights into the process of the Neolithization in the Near East based on a bioarchaeological approach integrating isotopic and archaeogenetic analyses on the bone remains recovered from Nevalı Çori, a site occupied from the early PPNB in Turkey where some of the earliest evidence of animal and plant domestication emerged, and from Ba'ja, a typical late PPNB site in Jordan. In addition, we present the archaeological sequence of Nevalı Çori together with newly generated radiocarbon dates. Our results are based on strontium (87Sr/86Sr), carbon, and oxygen (δ18O and δ13Ccarb) isotopic analyses conducted on 28 human and 29 animal individuals from the site of Nevalı Çori. 87Sr/86Sr results indicate mobility and connection with the contemporaneous surrounding sites during the earlier PPNB prior to an apparent decline in this mobility at a time of growing reliance on domesticates. Genome-wide data from six human individuals from Nevalı Çori and Ba'ja demonstrate a diverse gene pool at Nevalı Çori that supports connectedness within the Fertile Crescent during the earlier phases of Neolithization and evidence of consanguineous union in the PPNB Ba'ja and the Iron Age Nevalı Çori

Threads of memory: Reviving the ornament of a dead child at the Neolithic village of Ba`ja (Jordan)

In 2018, a well-constructed cist-type grave was discovered at Ba`ja, a Neolithic village (7,400–6,800 BCE) in Southern Jordan. Underneath multiple grave layers, an 8-year-old child was buried in a fetal position. Over 2,500 beads were found on the chest and neck, along with a double perforated stone pendant and a delicately engraved mother-of-pearl ring discovered among the concentration of beads. The first was found behind the neck, and the second on the chest. The meticulous documentation of the bead distribution indicated that the assemblage was a composite ornament that had gradually collapsed, partly due to the burying position. Our aim was to challenge time degradation and to reimagine the initial composition in order to best explore the significance of this symbolic category of material culture, not as mere group of beads, but as an ornamental creation with further aesthetic, artisanal and socioeconomic implications. The reconstruction results exceeded our expectations as it revealed an imposing multi-row necklace of complex structure and attractive design. Through multiple lines of evidence, we suggest that the necklace was created at Ba`ja, although significant parts of beads were made from exotic shells and stones, including fossil amber, an unprecedented material never attested before for this period. The retrieval of such an ornament from life and its attribution to a young dead child highlights the significant social status of this individual. Beyond the symbolic functions related to identity, the necklace is believed to have played a key role in performing the inhumation rituals, understood as a public event gathering families, relatives, and people from other villages. In this sense, the necklace is not seen as belonging completely to the realm of death but rather to the world of the living, materializing a collective memory and shared moments of emotions and social cohesion