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The subject of this thesis is the experimental investigation of the neutron-capture cross sections of the neutron-rich, short-lived boron isotopes 13B and 14B, as they are thought to influence the rapid neutron-capture process (r process) nucleosynthesis in a neutrino-driven wind scenario.
The 13;14B(n,g)14;15B reactions were studied in inverse kinematics via Coulomb dissociation at the LAND/R3B setup (Reactions with Relativistic Radioactive Beams). A radioactive beam of 14;15B was produced via in-flight fragmentation and directed onto a lead-target at about 500 AMeV. The neutron breakup of the projectile within the electromagnetic field of the target nucleus was investigated in a kinematically complete measurement. All outgoing reaction products were detected and analyzed in order to reconstruct the excitation energy.
The differential Coulomb dissociation cross sections as a function of the excitation energy were obtained and first experimental constraints on the photoabsorption and the neutron-capture cross sections were deduced. The results were compared to theoretical approximations of the cross sections in question. The Coulomb dissociation cross section of 15B into 14B(g.s.) + n was determined to be s(15B;14B(g:s:)+n) CD = 81(8stat)(10syst) mb ; while the Coulomb dissociation cross section of 14B into a neutron and 13B in its ground state was found to be s(14B;13B(g:s:)+n) CD = 281(25stat)(43syst) mb: Furthermore, new information on the nuclear structure of 14B were achieved, as the spectral shape of the differential Coulomb dissociation cross section indicates a halolike structure of the nucleus.
Additionally, the Coulomb dissociation of 11Be was investigated and compared to previous measurements in order to verify the present analysis. The corresponding Coulomb dissociation cross section of 11Be into 10Be(g.s.) + n was found to be 450(40stat)(54syst ) mb, which is in good agreement with the results of Palit et al.
1D-3D hybrid modeling : from multi-compartment models to full resolution models in space and time
(2014)
Investigation of cellular and network dynamics in the brain by means of modeling and simulation has evolved into a highly interdisciplinary field, that uses sophisticated modeling and simulation approaches to understand distinct areas of brain function. Depending on the underlying complexity, these models vary in their level of detail, in order to cope with the attached computational cost. Hence for large network simulations, single neurons are typically reduced to time-dependent signal processors, dismissing the spatial aspect of each cell. For single cell or networks with relatively small numbers of neurons, general purpose simulators allow for space and time-dependent simulations of electrical signal processing, based on the cable equation theory. An emerging field in Computational Neuroscience encompasses a new level of detail by incorporating the full three-dimensional morphology of cells and organelles into three-dimensional, space and time-dependent, simulations. While every approach has its advantages and limitations, such as computational cost, integrated and methods-spanning simulation approaches, depending on the network size could establish new ways to investigate the brain. In this paper we present a hybrid simulation approach, that makes use of reduced 1D-models using e.g., the NEURON simulator—which couples to fully resolved models for simulating cellular and sub-cellular dynamics, including the detailed three-dimensional morphology of neurons and organelles. In order to couple 1D- and 3D-simulations, we present a geometry-, membrane potential- and intracellular concentration mapping framework, with which graph- based morphologies, e.g., in the swc- or hoc-format, are mapped to full surface and volume representations of the neuron and computational data from 1D-simulations can be used as boundary conditions for full 3D simulations and vice versa. Thus, established models and data, based on general purpose 1D-simulators, can be directly coupled to the emerging field of fully resolved, highly detailed 3D-modeling approaches. We present the developed general framework for 1D/3D hybrid modeling and apply it to investigate electrically active neurons and their intracellular spatio-temporal calcium dynamics.
In the title solvate, C14H12N2O·0.5C6H6, the complete benzene molecule is generated by a crystallographic inversion centre. The dihedral angle between the planes of the benzimidazole moiety and the phenol substituent is 75.28 (3)°. In the crystal, O—H⋯N hydrogen bonds link the molecules into parallel chains propagating along [100]. The molecules are further connected by C—H⋯π interactions.
The radiative capture cross section of 238U is very important for the developing of new reactor technologies and the safety of existing ones. Here the preliminary results of the 238U(n,γ) cross section measurement performed at n_TOF with C6D6 scintillation detectors are presented, paying particular attention to data reduction and background subtraction.
In the title compound, C19H24N2O2, a di-Mannich base derived from 2-methylphenol and 1,3,6,8-tetraazatricyclo[4.4.1.13,8]dodecane, the imidazolidine ring adopts a twist conformation, with a twist about the ring N—C bond [C—N—C—C torsion angle = −44.34 (14)°]. The two 2-hydroxy-3-methylbenzyl groups are located in trans positions with respect to the imidazolidine fragment. The structure displays two intramolecular O—H⋯N hydrogen bonds, which each form an S(6) ring motif. In the crystal, the molecules are linked by weak C—H⋯O interactions with a bifurcated acceptor, forming a three-dimensional network.
For faunistic research on a certain animal group, knowledge of the situation in surrounding countries is a necessity. The presence of certain species in neighbouring regions, together with notes on their distribution and trends, offers valuable information for the interpretation of the status of these species in one’s own study area. Changes in the national fauna – e.g. the discovery of a new species – can often better be explained when integrating information on the status of species in nearby countries. Distribution atlases are therefore not only valuable publications for the country of concern, but also for other countries in the same region.
Andreas Fahrmeir’s history of the first half of the "long nineteenth century" begins with a disdainful Arthur Young travelling through France at the beginning of 1790 and ends with London’s Great Exhibition of 1851. The contrasting fortunes of France and Great Britain exemplify the contrasting concepts of the title. While the former experienced at least eleven contested regime changes – 1789, 1792, 1793, 1794, 1799, 1814, 1815 (twice), 1830, 1848 and 1850 – the British political system endured, albeit modified by reforms. Moreover, revolutionary-Napoleonic France was responsible for numerous revolutions from above elsewhere, uprooting old regimes and creating satellite states right across the continent, from the Batavian Republic to the Grand Duchy of Warsaw. Old Europe was not restored in 1815. With the Holy Roman Empire gone for good, the Low Countries combined in a single kingdom, Poland expunged from the map once again and the Habsburg Empire much more of an Italian and Balkan power than in the past, quite a new order had emerged. The shallow roots of the new creations ensured their future fragility. ...
Published in good time for the 2014 "Karlsjahr", marking 1200 years since the emperor’s death, Johannes Fried’s latest book is intended to make specialist scholarship on Charlemagne accessible to a broad audience. Judging by the impressive sales figures, it has admirably fulfilled that purpose. That is not however to say that it is an anodyne synthesis of current research. The picture of the Frankish ruler it provides is very much the author’s own, as he himself emphasises, so there is little danger that it might be lost to sight amongst the many other biographies currently available. ...
The volume under review contains the published proceedings of a conference held in 2009 with the challenging title, "Merowingische Monetarmünzen und der Beginn des Mittelalters". These Merovingian "Monetarmünzen" are a distinctive group of coins of which less than 10 000 are currently known. Quite suddenly, in the late sixth century, this type of gold coinage appears, with the name of a moneyer ( monetarius ) on the obverse and the place name on the reverse (presumably, but not necessarily in all instances, the mint). Thus, over a thousand moneyers and 722 place names are recorded, many only attested once or twice. In the late 7 th c. these coins slowly give way to a system based on the silver penny/denier, no longer showing names of moneyers. Who were these moneyers? What was their relationship with the court and the kings? To what ends were those coins produced, and how were they used in daily commerce? Why are so many different mints attested? These questions have occupied scholars for several generations now. However, Jarnut and Strothmann have added a new perspective: in how far are these coinages and the associated monetary policy a continuation of late Roman practices, or do they represent something altogether different and can, therefore, be understood as an expression of a fundamentally altered society that could be termed medieval? ...