1,078 research outputs found
Calculation of conventional and prompt lepton fluxes at very high energy
An efficient method for calculating inclusive conventional and prompt
atmospheric leptons fluxes is presented. The coupled cascade equations are
solved numerically by formulating them as matrix equation. The presented
approach is very flexible and allows the use of different hadronic interaction
models, realistic parametrizations of the primary cosmic-ray flux and the
Earth's atmosphere, and a detailed treatment of particle interactions and
decays. The power of the developed method is illustrated by calculating lepton
flux predictions for a number of different scenarios.Comment: 8 pages, 10 figures, for Proceedings of the International Symposium
for Very-High Energy Cosmic-Ray Interactions (ISVHECRI 2014
Sibyll: ad-hoc modifications for an improved description of muon data in extensive air showers
Current simulations of air showers produced by ultra-high energy cosmic rays
(UHECRs) do not satisfactorily describe recent experimental data, particularly
when looking at the muonic shower component relative to the electromagnetic
one. Discrepancies can be seen in both average values and on an individual
shower-by-shower basis. It is thought that the muonic part of the air showers
isn't accurately represented in simulations, despite various attempts to boost
the number of muons within standard hadronic interaction physics. In this
study, we investigate whether modifying the final state of events created with
Sibyll~2.3d in air shower simulations can achieve a more consistent description
of the muon content observed in experimental data. We create several scenarios
where we separately increase the production of baryons, , and strange
particles to examine their impact on realistic air shower simulations. Our
results suggest that these ad-hoc modifications can improve the simulations,
providing a closer match to the observed muon content in air showers. One
side-effect of the increased muon production in the considered model versions
is a smaller difference in the predicted total muon numbers for proton and iron
showers. However, more research is needed to find out whether any of these
adjustments offers a realistic solution to the mismatches seen in data, and to
identify the precise physical process causing these changes in the model. We
hope that these modified model versions will also help to develop improved
machine-learning analyses of air shower data and to estimate sys.{}
uncertainties related to shortcomings of hadronic interaction models
The hadronic interaction model SIBYLL 2.3c and Feynman scaling
The Monte Carlo model Sibyll has been designed for efficient simulation of
hadronic multiparticle production up to the highest energies as needed for
interpreting cosmic ray measurements. For more than 15 years, version 2.1 of
Sibyll has been one of the standard models for air shower simulation. Motivated
by data of LHC and fixed-target experiments and a better understanding of the
phenomenology of hadronic interactions, we have developed an improved version
of this model, version 2.3, which has been released in 2016. In this
contribution we present a revised version of this model, called Sibyll 2.3c,
that is further improved by adjusting particle production spectra to match the
expectation of Feynman scaling in the fragmentation region. After a brief
introduction to the changes implemented in Sibyll 2.3 and 2.3c with respect to
Sibyll 2.1, the current predictions of the model for the depth of shower
maximum, the number of muons at ground, and the energy spectrum of muons in
extensive air showers are presented.Comment: 35th International Cosmic Ray Conferenc
Sibyll: ad-hoc modifications for an improved description of muon data in extensive air showers
Folding and unfolding of a triple-branch DNA molecule with four conformational states
Single-molecule experiments provide new insights into biological processes
hitherto not accessible by measurements performed on bulk systems. We report on
a study of the kinetics of a triple-branch DNA molecule with four
conformational states by pulling experiments with optical tweezers and
theoretical modelling. Three distinct force rips associated with different
transitions between the conformational states are observed in the folding and
unfolding trajectories. By applying transition rate theory to a free energy
model of the molecule, probability distributions for the first rupture forces
of the different transitions are calculated. Good agreement of the theoretical
predictions with the experimental findings is achieved. Furthermore, due to our
specific design of the molecule, we found a useful method to identify
permanently frayed molecules by estimating the number of opened basepairs from
the measured force jump values.Comment: 17 pages, 12 figure
The multiple signaling modalities of adhesion G protein-coupled receptor GPR126 in development
The G protein-coupled receptor (GPCR) superfamily is the largest known receptor family in the human genome. Although the family of adhesion GPCRs comprises the second largest sub-family, their function is poorly understood. Here, we review the current knowledge about the adhesion GPCR family member GPR126. GPR126 possesses a signal peptide, a 7TM domain homologous to secretin-like GPCRs, a GPS motif and an extended N-terminus containing a CUB (Complement, Uegf, Bmp1) domain, a PTX (Pentraxin) domain, a hormone binding domain and 27 putative N-glycosylation sites. Knockdown and knockout experiments in zebrafish and mice have demonstrated that Gpr126 plays an essential role in neural, cardiac and ear development. In addition, genome-wide association studies have implicated variations at the GPR126 locus in obstructive pulmonary dysfunction, in scoliosis and as a determinant of trunk length and body height. Gpr126 appears to exert its function depending on the organ system via G protein- and/or N-terminus-dependent signaling. Here, we review the current knowledge about Gpr126, which, due to the variety of its functions and its multiple signaling modalities, provides a model adhesion GPCR to understand general functional concepts utilized by adhesion GPCRs
The multiple signaling modalities of adhesion G protein-coupled receptor GPR126 in development
The G protein-coupled receptor (GPCR) superfamily is the largest known receptor family in the human genome. Although the family of adhesion GPCRs comprises the second largest sub-family, their function is poorly understood. Here, we review the current knowledge about the adhesion GPCR family member GPR126. GPR126 possesses a signal peptide, a 7TM domain homologous to secretin-like GPCRs, a GPS motif and an extended N-terminus containing a CUB (Complement, Uegf, Bmp1) domain, a PTX (Pentraxin) domain, a hormone binding domain and 27 putative N-glycosylation sites. Knockdown and knockout experiments in zebrafish and mice have demonstrated that Gpr126 plays an essential role in neural, cardiac and ear development. In addition, genome-wide association studies have implicated variations at the GPR126 locus in obstructive pulmonary dysfunction, in scoliosis and as a determinant of trunk length and body height. Gpr126 appears to exert its function depending on the organ system via G-protein- and/or N-terminus-dependent signaling. Here, we review the current knowledge about Gpr126, which, due to the variety of its functions and its multiple signaling modalities, provides a model adhesion GPCR to understand general functional concepts utilized by adhesion GPCRs
The Threat of Capital Drain: A Rationale for Public Banks?
This paper yields a rationale for why subsidized public banks may be desirable from a regional perspective in a financially integrated economy. We present a model with credit rationing and heterogeneous regions in which public banks prevent a capital drain from poorer to richer regions by subsidizing local depositors, for example, through a public guarantee. Under some conditions, cooperative banks can perform the same function without any subsidization; however, they may be crowded out by public banks. We also discuss the impact of the political structure on the emergence of public banks in a political-economy setting and the role of interregional mobility
Optical inter-site spin transfer probed by energy and spin-resolved transient absorption spectroscopy
Optically driven spin transport is the fastest and most efficient process to manipulate macroscopic magnetization as it does not rely on secondary mechanisms to dissipate angular momentum. In the present work, we show that such an optical inter-site spin transfer (OISTR) from Pt to Co emerges as a dominant mechanism governing the ultrafast magnetization dynamics of a CoPt alloy. To demonstrate this, we perform a joint theoretical and experimental investigation to determine the transient changes of the helicity dependent absorption in the extreme ultraviolet spectral range. We show that the helicity dependent absorption is directly related to changes of the transient spin-split density of states, allowing us to link the origin of OISTR to the available minority states above the Fermi level. This makes OISTR a general phenomenon in optical manipulation of multi-component magnetic systems. Optically driven spin transfer is the fastest process to manipulate magnetism. Here, the authors show that this process emerges as the dominant mechanism in femtosecond spin dynamics enabling to the engineering of functional magnetic systems for future all optical technologies
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