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Wood M.,SLAC | Jogler T.,SLAC | Dumm J.,The Oskar Klein Center | Funk S.,SLAC | Funk S.,Friedrich Alexander University Erlangen Nurnberg
Astroparticle Physics | Year: 2016

We present studies for optimizing the next generation of ground-based imaging atmospheric Cherenkov telescopes (IACTs). Results focus on mid-sized telescopes (MSTs) for CTA, detecting very high energy gamma rays in the energy range from a few hundred GeV to a few tens of TeV. We describe a novel, flexible detector Monte Carlo package, FAST (FAst Simulation for imaging air cherenkov Telescopes), that we use to simulate different array and telescope designs. The simulation is somewhat simplified to allow for efficient exploration over a large telescope design parameter space. We investigate a wide range of telescope performance parameters including optical resolution, camera pixel size, and light collection area. In order to ensure a comparison of the arrays at their maximum sensitivity, we analyze the simulations with the most sensitive techniques used in the field, such as maximum likelihood template reconstruction and boosted decision trees for background rejection. Choosing telescope design parameters representative of the proposed Davies-Cotton (DC) and Schwarzchild-Couder (SC) MST designs, we compare the performance of the arrays by examining the gamma-ray angular resolution and differential point-source sensitivity. We further investigate the array performance under a wide range of conditions, determining the impact of the number of telescopes, telescope separation, night sky background, and geomagnetic field. We find a 30-40% improvement in the gamma-ray angular resolution at all energies when comparing arrays with an equal number of SC and DC telescopes, significantly enhancing point-source sensitivity in the MST energy range. We attribute the increase in point-source sensitivity to the improved optical point-spread function and smaller pixel size of the SC telescope design. © 2015 Elsevier B.V. All rights reserved.


PubMed | A Private Research Facility and Friedrich Alexander University Erlangen Nurnberg
Type: Journal Article | Journal: Chemistry & biodiversity | Year: 2016

In this second part of the investigation of volatiles and semivolatiles in Boswellia gum resins, an additional five less common species were analyzed by (SPME-)GC/MS, namely B.ameero, B.elongata, B.neglecta, B.popoviana, and B.rivae. Moreover, the results of hybridization experiments are reported in combination with the volatile composition of their gum resins. Our study shows that B.sacra benefits from an intraspecific cross-pollination, as the resulting hybrid B.sacra var. supersacra has a far higher seed germination rate and viability.


Trammell B.,ETH Zurich | Casas P.,FTW | Rossi D.,University Pierre and Marie Curie | Bar A.,Friedrich Alexander University Erlangen Nurnberg | And 4 more authors.
IEEE Communications Magazine | Year: 2014

The Internet¿s universality is based on its decentralization and diversity. However, its distributed nature leads to operational brittleness and difficulty in identifying the root causes of performance and availability issues, especially when the involved systems span multiple administrative domains. The first step to address this fragmentation is coordinated measurement: we propose to complement the current Internet¿s data and control planes with a measurement plane, or mPlane for short. mPlane¿s distributed measurement infrastructure collects and analyzes traffic measurements at a wide variety of scales to monitor the network status. Its architecture is centered on a flexible control interface, allowing the incorporation of existing measurement tools through lightweight mPlane proxy components, and offering dynamic support for new capabilities. A focus on automated, iterative measurement makes the platform well-suited to troubleshooting support. This is supported by a reasoning system, which applies machine learning algorithms to learn from success and failure in drilling down to the root cause of a problem. This article describes the mPlane architecture and shows its applicability to several distributed measurement problems involving content delivery networks and Internet service roviders. A first case study presents the tracking and iterative analysis of cache selection policies in Akamai, while a second example focuses on the cooperation between Internet service providers and content delivery networks to better orchestrate their traffic engineering decisions and jointly improve their performance. © 2014 IEEE.


Alberti M.,Friedrich Alexander University Erlangen Nurnberg | Fursich F.T.,Friedrich Alexander University Erlangen Nurnberg | Pandey D.K.,University of Rajasthan
Sedimentology | Year: 2013

In large parts of the Kachchh Basin, a Mesozoic rift basin situated in western India, the Oxfordian succession is characterized by strong condensation and several depositional gaps. The top layer of the Early to Middle Oxfordian Dhosa Oolite member, for which the term 'Dhosa Conglomerate Bed' is proposed, is an excellent marker horizon. Despite being mostly less than 1m thick, this unit can be followed for more than 100km throughout the Kachchh Mainland. A detailed sedimentological analysis has led to a complex model for its formation. Signs of subaerial weathering, including palaeokarst features, suggest at least two phases of emersion of the area. Metre-sized concretionary slabs floating in a fine-grained matrix, together with signs of synsedimentary tectonics, point to a highly active fault system causing recurrent earthquakes in the basin. The model takes into account information from outcrops outside the Kachchh Mainland and thereby considerably refines the current understanding of the basin history during the Late Jurassic. Large fault systems and possibly the so-called Median High uplift separated the basin into several sub-basins. The main reason for condensation in the Oxfordian succession is an inversion that affected large parts of the basin by cutting them off from the sediment supply. The Dhosa Conglomerate Bed is an excellent example, demonstrating the potential of condensed units in reconstructing depositional environments and events that took place during phases of non-deposition. Although condensed sequences occur frequently throughout the sedimentary record, they are particularly common around the Callovian to Oxfordian transition. A series of models has been proposed to explain these almost worldwide occurrences, ranging from eustatic sea-level highstands to glacial phases connected with regressions. The succession of the Kachchh Basin shows almost stable conditions across this boundary with only a slight fall in relative sea-level, reaching its minimum not before the late Early Oxfordian. © 2012 The Authors. Journal compilation © 2012 International Association of Sedimentologists.


Zlatanov N.,University of British Columbia | Ikhlef A.,Toshiba Corporation | Islam T.,University of British Columbia | Schober R.,Friedrich Alexander University Erlangen Nurnberg
IEEE Communications Magazine | Year: 2014

Cooperative communication can increase the throughput and/or extend the coverage of wireless networks. However, in conventional cooperative networks, half-duplex relays transmit and receive under a prefixed schedule, which does not allow them to exploit the best receiving and transmitting channels, thus limiting performance. Recently, new protocols have been proposed that circumvent this problem by making use of the additional flexibility offered by relays with buffers. Compared to conventional relaying protocols, these buffer-aided protocols provide significant gains in terms of throughput, diversity, and signal-to-noise ratio. This article outlines several buffer-aided relaying protocols for different network topologies, including one-way single- and multi-relay networks as well as two-way single-relay networks. Moreover, some practical challenges inherent to buffer-aided relaying, such as increased delay and complexity, and topics for future research are discussed. Copyright © 2014 IEEE.


Witzgall C.,Friedrich Alexander University Erlangen Nurnberg | Wartzack S.,Friedrich Alexander University Erlangen Nurnberg
DFX 2015: Proceedings of the 26th Symposium Design for X | Year: 2015

A simplified approach towards a simplified integrative simulation for short fibre reinforced polymers (SFRP) has been proposed by Gruber and Wartzack. It uses orientation information from injection moulding simulation directly inside a structural or crash simulation. For describing the complex material behavior of SFRP, a layerwise stacking of simple material models is used. Thus, only standard material models which can be computed efficiently have to be used. Within the present paper, the simulative approach is to be verified and validated, i.e. the physical plausibility and the usability for loadcases with elevated strain rates are examined.


Pattinson D.,Australian National University | Schroder L.,Friedrich Alexander University Erlangen Nurnberg
Electronic Notes in Theoretical Computer Science | Year: 2015

Comodels of Lawvere theories, i.e. models in Setop, model state spaces with algebraic access operations. Standard equational reasoning is known to be sound but incomplete for comodels. We give two sound and complete calculi for equational reasoning over comodels: an inductive calculus for equality-on-the-nose, and a coinductive/inductive calculus for equality modulo bisimulation which captures bisimulations syntactically through non-wellfounded proofs. © 2015 Published by Elsevier B.V.


Kestel P.,Friedrich Alexander University Erlangen Nurnberg | Wartzack S.,Friedrich Alexander University Erlangen Nurnberg
DFX 2015: Proceedings of the 26th Symposium Design for X | Year: 2015

Computer-based simulation techniques such as finite element analysis gain huge attention in engineering design practice. However, an efficient use of simulation requires an early application in the product development process. Furthermore, extensive specialist knowledge is a crucial prerequisite to perform reliable and meaningful simulations. Due to time constraints, design accompanying simulations are performed only rarely by experienced simulation engineers or, if they are performed by less experienced users, are not sufficiently accurate. Hence, this paper presents a concept for a knowledge based FEA assistance system for designers to efficiently capture and provide necessary knowledge of simulation experts in early development phases.


PubMed | Friedrich - Alexander - University, Erlangen - Nuremberg and Friedrich Alexander University Erlangen Nurnberg
Type: | Journal: Journal of visualized experiments : JoVE | Year: 2017

The aim of this study was to establish a standardized protocol for drug-induced sleep endoscopy (DISE) to differentiate obstruction patterns in obstructive sleep apnea (OSA). Target-controlled infusion (TCI) of the sedative propofol was combined with real-time monitoring of the depth of sedation using bispectral analysis. In an observational study 57 patients (mean age 44.8 years, SD 10.5; mean apnea hypopnea Index (AHI) 30.8/hr, SD 21.6, mean BMI 28.2 kg/m


PubMed | Friedrich Alexander University Erlangen Nurnberg
Type: Journal Article | Journal: Chemistry & biodiversity | Year: 2016

The genus Boswellia comprises many species which are famous for their production of frankincense, a fragrant gum resin. In the published literature, manifold studies on the volatiles and semivolatiles in individual samples of these gum resins exist, yet very few studies have investigated multiple samples. Contradictory results with regard to the volatile composition exist in literature. In this first part of the study, a large sample set (n=46) of mostly commercially obtained gum resins and essential oils was investigated by solid-phase microextraction gas chromatography/mass spectrometry. A total of 216 compounds were identified or tentatively identified from the four commercially relevant species, namely B.sacra, B.serrata, B.papyrifera, and B.frereana, and the statistical evaluation of the resulting chemical profiles allowed a clear distinction between the species by their volatile profile. With only few exceptions, the designated species was found to be in accordance with the composition reported in reliable literature sources and detected in botanically identified samples. Chemotaxonomic marker substances were suggested to facilitate the differentiation of commercial gum resins or essential oils based on their volatile profile.

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