1,684 research outputs found
Drumlins des Drenthe-Stadiums am Nordostrand der Westfälischen Bucht
Am Rande der Westfälischen Bucht liegen bei Versmold und Gütersloh zwei Drumlinfelder. Die zusammen über 60 Rücken, die aus Sand und Geschiebelehm bestehen, wurden durch einen Gletscher des Inlandeises geformt, der aus der Westfälischen Bucht gegen die Randhöhen des Teutoburger Waldes vordrang. Es handelt sich um die Erstbeschreibung von Drumlins im Altmoränengebiet Nordwestdeutschlands.At the border of the Westphalian lowland-bay you can find two drumlin-areas northeast of Versmold and Gütersloh respectively. There are all together more than sixty ridges consisting of sand and moralne, and formed by a glacier of the inland ice coming from the Westphalian lowland-bay and proceeding towards the bordering chain of the Teutoburger Wald hills. This is the first time that drumlins are described in the Saalian old moraines of Northwest Germany
Grobgeschiebestatistik als Hilfsmittel bei der Kartierung eiszeitlicher Halte
Zu den Zielen der Eiszeitforschung gehört das Erfassen der Stillstandslagen des nordischen Inlandeises. Im Tiefland haben sich dabei Morphologie und Leitgeschiebestatistik bewährt. In mittelgebirgigen Landschaften setzen erosive Abtragung der Moränen und fluviatile Umlagerung von Geschieben der Anwendung dieser Methoden oft enge Grenzen. Hier bietet sich als zusätzliche Methode die Grobgeschiebestatistik an. Danach lassen sich glaziale Halte auch aus der Ansammlung von fluviatil nicht transportablen groben nordischen Blöcken in schmalen Streifen im Gelände ablesen. Der Beitrag befaßt sich weiterhin mit den kritischen Einschränkungen des Aussagewertes der Methode, vor allem in Relation zu den herkömmlichen Verfahren. Einige Hinweise sollen der praktischen Arbeit mit der Grobgeschiebestatistik im Gelände dienen.researc
Eine saaleeiszeitliche Mittelmoräne zwischen Teutoburger Wald und Wiehengebirge
In der Arbeit wird erstmals für den nordwestdeutschen Raum eine saaleeiszeitliche Mittelmoräne beschrieben. Ihre Bildung ist eine Folge des Einflusses des Reliefs, besonders der Pässe des Wiehengebirges, auf das von Norden in die Herforder Liasmulde vordringende Inlandeis.researc
Velocity Tails for Inelastic Maxwell Models
We study the velocity distribution function for inelastic Maxwell models,
characterized by a Boltzmann equation with constant collision rate, independent
of the energy of the colliding particles. By means of a nonlinear analysis of
the Boltzmann equation, we find that the velocity distribution function decays
algebraically for large velocities, with exponents that are analytically
calculated.Comment: 4 pages, 2 figure
Bath generated work extraction and inversion-free gain in two-level systems
The spin-boson model, often used in NMR and ESR physics, quantum optics and
spintronics, is considered in a solvable limit to model a spin one-half
particle interacting with a bosonic thermal bath. By applying external pulses
to a non-equilibrium initial state of the spin, work can be extracted from the
thermalized bath. It occurs on the timescale \T_2 inherent to transversal
(`quantum') fluctuations. The work (partly) arises from heat given off by the
surrounding bath, while the spin entropy remains constant during a pulse. This
presents a violation of the Clausius inequality and the Thomson formulation of
the second law (cycles cost work) for the two-level system.
Starting from a fully disordered state, coherence can be induced by employing
the bath. Due to this, a gain from a positive-temperature (inversion-free)
two-level system is shown to be possible.Comment: 4 pages revte
Social Preferences and the Efficiency of Bilateral Exchange
Under what conditions do social preferences, such as altruism or a concern for fair outcomes, generate efficient trade? I analyze theoretically a simple bilateral exchange game: Each player sequentially takes an action that reduces his own material payoff but increases the other player’s. Each player’s preferences may depend on both his/her own material payoff and the other player’s. I identify necessary conditions and sufficient conditions on the players’ preferences for the outcome of their interaction to be Pareto efficient. The results have implications for interpreting the rotten kid theorem, gift exchange in the laboratory, and gift exchange in the field
Towards automatic pulmonary nodule management in lung cancer screening with deep learning
The introduction of lung cancer screening programs will produce an
unprecedented amount of chest CT scans in the near future, which radiologists
will have to read in order to decide on a patient follow-up strategy. According
to the current guidelines, the workup of screen-detected nodules strongly
relies on nodule size and nodule type. In this paper, we present a deep
learning system based on multi-stream multi-scale convolutional networks, which
automatically classifies all nodule types relevant for nodule workup. The
system processes raw CT data containing a nodule without the need for any
additional information such as nodule segmentation or nodule size and learns a
representation of 3D data by analyzing an arbitrary number of 2D views of a
given nodule. The deep learning system was trained with data from the Italian
MILD screening trial and validated on an independent set of data from the
Danish DLCST screening trial. We analyze the advantage of processing nodules at
multiple scales with a multi-stream convolutional network architecture, and we
show that the proposed deep learning system achieves performance at classifying
nodule type that surpasses the one of classical machine learning approaches and
is within the inter-observer variability among four experienced human
observers.Comment: Published on Scientific Report
Spin Motion in Electron Transmission through Ultrathin Ferromagnetic Films Accessed by Photoelectron Spectroscopy
Ab initio and model calculations demonstrate that the spin motion of
electrons transmitted through ferromagnetic films can be analyzed in detail by
means of angle- and spin-resolved core-level photoelectron spectroscopy. The
spin motion appears as precession of the photoelectron spin polarization around
and as relaxation towards the magnetization direction. In a systematic study
for ultrathin Fe films on Pd(001) we elucidate its dependence on the Fe film
thickness and on the Fe electronic structure. In addition to elastic and
inelastic scattering, the effect of band gaps on the spin motion is addressed
in particular.Comment: 4 pages, 5 figure
Work extraction in the spin-boson model
We show that work can be extracted from a two-level system (spin) coupled to
a bosonic thermal bath. This is possible due to different initial temperatures
of the spin and the bath, both positive (no spin population inversion) and is
realized by means of a suitable sequence of sharp pulses applied to the spin.
The extracted work can be of the order of the response energy of the bath,
therefore much larger than the energy of the spin. Moreover, the efficiency of
extraction can be very close to its maximum, given by the Carnot bound, at the
same time the overall amount of the extracted work is maximal. Therefore, we
get a finite power at efficiency close to the Carnot bound.
The effect comes from the backreaction of the spin on the bath, and it
survives for a strongly disordered (inhomogeneously broadened) ensemble of
spins. It is connected with generation of coherences during the work-extraction
process, and we derived it in an exactly solvable model. All the necessary
general thermodynamical relations are derived from the first principles of
quantum mechanics and connections are made with processes of lasing without
inversion and with quantum heat engines.Comment: 30 pages, 6 figure
Analysis of host responses to Mycobacterium tuberculosis antigens in a multi-site study of subjects with different TB and HIV infection states in sub-Saharan Africa.
BACKGROUND: Tuberculosis (TB) remains a global health threat with 9 million new cases and 1.4 million deaths per year. In order to develop a protective vaccine, we need to define the antigens expressed by Mycobacterium tuberculosis (Mtb), which are relevant to protective immunity in high-endemic areas. METHODS: We analysed responses to 23 Mtb antigens in a total of 1247 subjects with different HIV and TB status across 5 geographically diverse sites in Africa (South Africa, The Gambia, Ethiopia, Malawi and Uganda). We used a 7-day whole blood assay followed by IFN-Îł ELISA on the supernatants. Antigens included PPD, ESAT-6 and Ag85B (dominant antigens) together with novel resuscitation-promoting factors (rpf), reactivation proteins, latency (Mtb DosR regulon-encoded) antigens, starvation-induced antigens and secreted antigens. RESULTS: There was variation between sites in responses to the antigens, presumably due to underlying genetic and environmental differences. When results from all sites were combined, HIV- subjects with active TB showed significantly lower responses compared to both TST(-) and TST(+) contacts to latency antigens (Rv0569, Rv1733, Rv1735, Rv1737) and the rpf Rv0867; whilst responses to ESAT-6/CFP-10 fusion protein (EC), PPD, Rv2029, TB10.3, and TB10.4 were significantly higher in TST(+) contacts (LTBI) compared to TB and TST(-) contacts fewer differences were seen in subjects with HIV co-infection, with responses to the mitogen PHA significantly lower in subjects with active TB compared to those with LTBI and no difference with any antigen. CONCLUSIONS: Our multi-site study design for testing novel Mtb antigens revealed promising antigens for future vaccine development. The IFN-Îł ELISA is a cheap and useful tool for screening potential antigenicity in subjects with different ethnic backgrounds and across a spectrum of TB and HIV infection states. Analysis of cytokines other than IFN-Îł is currently on-going to determine correlates of protection, which may be useful for vaccine efficacy trials
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