PLANNING TO PLEASE CUSTOMERS

Abstract- The achievable rate of a coherent coded modulation (CM) digital communication system with data-aided channel estimation and a discrete, equiprobable symbol alphabet is derived under the assumption that the system operates on a flat fading MIMO channel and uses an interleaver to combat the bursty nature of the chan-nel. It is shown that linear minimum mean square er-ror (LMMSE) channel estimation directly follows from the derivation, and links average mutual information to the channel dynamics. Based on the assumption that known training symbols are transmitted, the achievable rate of the system is optimized with respect to the amount of training information needed. I

Colloquium: Atomic spin chains on surfaces

In the present Colloquium, we focus on the properties of 1-D magnetic systems on solid surfaces. From the emulation of 1-D quantum phases to the potential realization of Majorana edge states, spin chains are unique systems to study. The advent of scanning tunnelling microscope (STM) based techniques has permitted us to engineer spin chains in an atom-by-atom fashion via atom manipulation and to access their spin states on the ultimate atomic scale. Here, we present the current state of research on spin correlations and dynamics of atomic spin chains as studied by the STM. After a brief review of the main properties of spin chains on solid surfaces, we classify spin chains according to the coupling of their magnetic moments with the holding substrate. This classification scheme takes into account that the nature and lifetimes of the spin-chain excitation intrinsically depend on the holding substrate. We first show the interest of using insulating layers on metals, which generally results in an increase in the spin state's lifetimes such that their quantized nature gets evident and they are individually accessible. Next, we show that the use of semiconductor substrates promises additional control through the tunable electron density via doping. When the coupling to the substrate is increased for spin chains on metals, the substrate conduction electron mediated interactions can lead to emergent exotic phases of the coupled spin chain-substrate conduction electron system. A particularly interesting example is furnished by superconductors. Magnetic impurities induce states in the superconducting gap. Due to the extended nature of the spin chain, the in-gap states develop into bands that can lead to the emergence of 1-D topological superconductivity and, consequently to the appearance of Majorana edge states

Neue Erkenntnisse zur Ermüdungsfestigkeit und Prognose der Lebensdauer von einbetonierten Spannstählen bei sehr hohen Lastwechselzahlen

Für den Nachweis gegen Ermüdung von älteren bestehenden Spannbetonbrücken oder Neubauten werden Bemessungswöhlerlinien für Spannstahl im einbetonierten Zustand benötigt. Die bisherigen Versuche mit gekrümmten Spanngliedern im nachträglichen Verbund decken die Wöhlerlinie im Wesentlichen im Zeitfestigkeitsbereich ab. Nur sehr wenige Versuche weisen Lastspielzahlen über 10 Mio. auf, wobei keine echte Dauerfestigkeit erkennbar ist. Daher ist der Verlauf der Wöhlerlinie im Dauerfestigkeitsbereich im Wesentlichen hypothetisch festgelegt worden. Im Rahmen eines Teilprojektes im SFB 823 „Statistik nichtlinearer dynamischer Prozesse“ an der TU Dortmund wird die Ermüdungsfestigkeit einbetonierter Spannstähle im Bereich bis etwa 10^8 Lastzyklen experimentell untersucht. Des Weiteren wurden auf Grundlage der sehr umfangreichen Datenbasis verschiedener gemessener physikalischer Größen mit mathematisch statistischen Methoden mehrere Prognoseverfahren entwickelt. Diese ermöglichen bei vorgegebener Aussagewahrscheinlichkeit die Abschätzung eines Prognoseintervalls mit Mittelwert- und Quantilkurven für den Schädigungsverlauf

Prediction intervals for the failure time of prestressed concrete beams

The aim is the prediction of the failure time of prestressed concrete beams under low cyclic load. Since the experiments last long for low load, accelerated failure tests with higher load are conducted. However, the accelerated tests are expensive so that only few tests are available. To obtain a more precise failure time prediction, the additional information of time points of breakage of tension wires is used. These breakage time points are modeled by a nonlinear birth process. This allows not only point prediction of a critical number of broken tension wires but also prediction intervals which express the uncertainty of the prediction

Resistance to fatigue and prediction of lifetime of wire tendons cast into concrete up to 10^8 cycles

Usually for verification of compliance, the fatigue resistance of prestressing steel is determined from tests of naked specimens at 2 million cycles. However, for design the fatigue resistance of tendons cast into concrete, is substantially lower. To verify the resistance of existing older prestressed concrete bridges and for the design of new bridges, S-N curves of prestressing steel in curved steel ducts embedded into concrete are needed. In bridges, the load cycles due to heavy vehicles may rise up to about 10E8 cycles or even more. Previous tests with curved tendons in steel ducts primarily cover a range of up to about 20 million cycles. Thereby no real endurance strength has been estimated jet. Hence the S-N curves given in Eurocode 2 and Model Code 2010 are defined hypothetically for a range from 10^6 up to 10^8 and are not based on test results. The reason is that experimental investigations in a range up to 10 8 cycles are very expensive and also demand a very long duration. Essential progress results from the development of an optimized test setup that allows a frequency of 10Hz for the applied load cycles. Therewith, the experimental investigations up to 10^8 cycles have been done by means of prestressed concrete beams with embedded curved tendons in steel ducts. Furthermore, procedures to also forecast the lifetime in the case of very low stress ranges respectively the remaining lifetime of a running test had been developed in conjunction with an interdisciplinary research project. The procedures are based on refined statistical analysis of the extensively measured data including increase of crack width, strains, sound emission etc. Additionally the analysis of the latter leads to some interesting new perceptions

Radiotherapy in langerhans cell histiocytosis : a rare indication in a rare disease

Introduction: Langerhans Cell Histiocytosis (LCH) represents a rare benign disorder, previously designated as "Histiocytosis X", "Type II Histiocytosis" or "Langerhans Cell Granulomatosis". Clinical presentation includes osteolysis, ulcerations of skin and soft tissues but also involvement of the CNS is described.Because treatment concepts are not well defined the German Cooperative Group on Radiotherapy for Benign Diseases performed a retrospective analysis. Methods and material: Eight closely cooperating centres collected patients' data of the past 45 years. As study endpoints disease free survival, recurrent disease, death and therapy related side effects were defined. Results: A total of 80 patients with histologically proven LCH were irradiated within the past 45 years. According to the LCH classification of Greenberger et al. 37 patients had stage Ia, 21 patients stage Ib, 13 patients stage II and 9 patients stage IIIb and the median age was 29 years. The median Follow up was 54 months (range 9-134 months). A total of 39 patients had a surgical intervention and 23 patients a chemotherapy regimen.Radiation treatment was carried out with a median total dose of 15 Gy (range 3-50.4 Gy). The median single fraction was 2 Gy (range 1.8-3 Gy).Overall, 77% patients achieved a complete remission and 12.5% achieved a partial remission. The long-term control rate reached 80%. Within an actuarial overall 5-year survival of 90% no radiogenic side and late effects ≥EORTC/RTOG II° were observed. Conclusion: In the present study a large collective of irradiated patients was analysed. Radiotherapy (RT) is a very effective and safe treatment option and even low RT doses show sufficient local control

Search for charged stable massive particles with the ATLAS detector

A search for charged stable massive particles in 36.1 fb−1 of proton–proton collisions at √ s = 13 TeV with the ATLAS detector is presented. Since stable massive particles are not absorbed in the calorimeters their signature is equivalent to muons that propagate much slower than the speed of light due to their large mass and are highly ionising. The ionisation energy losses are measured in pixel clusters of the innermost tracking chambers, the propagation velocity β is determined by performing time-of-flight measurements. An in-depth timing calibration of the muon system is presented which significantly improves previous results and achieves the best ATLAS β resolution to-date. This involves the correction of temporal effects and determination of calibration constants for about 700 000 detector elements individually. The expected background is estimated in a purely data-driven manner. No statistically significant excess of events was observed in any signal region. The results are interpreted in various supersymmetric models predicting the existence of long-lived particles. Long-lived gluinos, originating from Split SUSY models, and long-lived bottom and top squarks that hadronise into R-hadrons were excluded at 95% CL up to masses of m(g˜) = 2015 GeV, m(b˜) = 1240 GeV and m(g˜) = 1325 GeV. Directly pair-produced long-lived staus from GMSB models are excluded to masses up to m(τ˜) = 420 GeV. Detector-stable charginos originating from mAMSB models can be ruled out up to masses of m(χ˜1±) = 1100 GeV. All limits are the most stringent constraints on stable SUSY particles and are a significant improvement over previously reported ATLAS and CMS results. To account for shorter lifetimes, model independence and possible charge-flip reactions the R-hadron analysis is also done disregarding all signals stemming from the muon system including triggering. No excess of events is observed and 95% CL exclusion limits are set resulting in the limits m(g˜) = 1950 GeV, m(b˜) = 1170 GeV and m(g˜) = 1220 GeV for gluinos, bottom and top squarks, respectively. Lastly, a novel trigger is introduced that is dedicated to slow-particle searches by considering two consecutive collision events thereby recovering muon-trigger efficiency for particles arriving out-of-time in the muon system