Particle-level pileup subtraction for jets and jet shapes

We present an extension to the jet area-based pileup subtraction for both jet kinematics and jet shapes. A particle-level approach is explored whereby the jet constituents are corrected or removed using an extension of the methods currently being employed by the LHC experiments. Several jet shapes and nominal jet radii are used to assess the performance in simulated events with pileup levels equivalent to approximately 30 and 100 interactions per bunch crossing, which are characteristic of both the LHC Run I and Run II conditions. An improved performance in removing the pileup contributions is found when using the new subtraction method. The performance of the new procedure is also compared to other existing methods

Regional determinants of new business formation in China: Prefecture-level evidence

Using a panel data model, we study the effects of regional and industry-level traits on new business formation (NBF) for 164 industries across 266 Chinese prefectures between 1998 and 2007. The objective is to provide empirical estimates on effects of prefecture traits on entry rates, and in particular on effects of prefecture knowledge capital stocks on R&D-intensive new business formation. In line with literature on knowledge spillovers, we find extensive evidence of a positive prefecture knowledge capital stock effect on R&D-intensive NBF rates, whereas knowledge capital stocks do not predict non R&D-intensive entry rates. Among regional and industry-level characteristics, we find that prefecture supplier and customer market strength are strongly linked to higher business entry rates. Our results for China contrast with recent findings on the effects of regional traits on firm entry rates in India and the US, indicating distinct regional patterns of Chinese entrepreneurship

A new Approach to Identification of Critical Elements in Railway Infrastructure

The paper contains a presentation of new approaches to solving the problem of identifying critical infrastructure elements in the railway sub-sector. The research objective was to analyse the procedures which are used to identify the potential elements of critical infrastructure in the transportation sector. Specific attention is paid to criteria of methods developed in Germany, the Czech Republic and Slovakia. The objective of the work is based on the analysis of the current state of art. The research also attempted to design an effective methodology which allows assessing the significance of rail infrastructure elements. The developed methodology should help to set a group of potential elements of critical infrastructure in the railway sub-sector. © 2017 The Authors.Grant Agency of Slovak Republic [1/0240/15]; Ministry of the Interior of the Czech Republic, project "RESILIENCE - Dynamic Resilience Evaluation of Interrelated Critical Infrastructure Subsystems

Untangling perceptual memory: hysteresis and adaptation map into separate cortical networks

Perception is an active inferential process in which prior knowledge is combined with sensory input, the result of which determines the contents of awareness. Accordingly, previous experience is known to help the brain “decide” what to perceive. However, a critical aspect that has not been addressed is that previous experience can exert 2 opposing effects on perception: An attractive effect, sensitizing the brain to perceive the same again (hysteresis), or a repulsive effect, making it more likely to perceive something else (adaptation). We used functional magnetic resonance imaging and modeling to elucidate how the brain entertains these 2 opposing processes, and what determines the direction of such experience-dependent perceptual effects. We found that although affecting our perception concurrently, hysteresis and adaptation map into distinct cortical networks: a widespread network of higher-order visual and fronto-parietal areas was involved in perceptual stabilization, while adaptation was confined to early visual areas. This areal and hierarchical segregation may explain how the brain maintains the balance between exploiting redundancies and staying sensitive to new information. We provide a Bayesian model that accounts for the coexistence of hysteresis and adaptation by separating their causes into 2 distinct terms: Hysteresis alters the prior, whereas adaptation changes the sensory evidence (the likelihood function)

Accidental Father-to-Son HIV-1 Transmission During the Seroconversion Period

A 4-year-old child born to an HIV-1 seronegative mother was diagnosed with HIV-1, the main risk factor being transmission from the child's father who was seroconverting at the time of the child's birth. In the context of a forensic investigation, we aimed to identify the source of infection of the child and date of the transmission event. Samples were collected from the father and child at two time points about 4 years after the child's birth. Partial segments of three HIV-1 genes (gag, pol, and env) were sequenced and maximum likelihood (ML) and Bayesian methods were used to determine direction and estimate date of transmission. Neutralizing antibodies were determined using a single cycle assay. Bayesian trees displayed a paraphyletic-monophyletic topology in all three genomic regions, with the father's host label at the root, which is consistent with father-to-son transmission. ML trees found similar topologies in gag and pol and a monophyletic-monophyletic topology in env. Analysis of the time of the most recent common ancestor of each HIV-1 gene population indicated that the child was infected shortly after the father. Consistent with the infection history, both father and son developed broad and potent HIV-specific neutralizing antibody responses. In conclusion, the direction of transmission implicated the father as the source of transmission. Transmission occurred during the seroconversion period when the father was unaware of the infection and was likely accidental. This case shows how genetic, phylogenetic, and serological data can contribute for the forensic investigation of HIV transmission.info:eu-repo/semantics/publishedVersio

Kinetische Monte-Carlo-Simulation mit variabler Barrierenhöhe an L12 <<[L 1 tief 2]>>-geordnetem Ni3Al <<[Ni tief 3 Al]>>

Im Rahmen dieser Diplomarbeit wird ein neues Modell zur Berechnung von Übergangsraten bei Atomsprungprozessen vorgestellt. Dieser realistischere Ansatz basiert hauptsächlich auf der Analyse von Sprungprofilen, die mit Hilfe von ab initio-Berechnungen erstellt wurden. Das neue Modell berücksichtigt die variable Barrierenhöhe bei Sprungprozessen und stellt somit eine Änderung der in der Literatur vorherrschenden Berechnungsart der Übergangsraten mit Hilfe konstanter Barrierenhöhe dar. Grundlegend hierfür ist der Einfluss des sogenannten '4-Atom-Fensters', das in der kubisch-flächenzentrierten Struktur auftritt, auf die Höhe der Barriere. Dieser neue Ansatz wird mit Hilfe von Monte-Carlo-Simulationen getestet und die ersten Ergebnisse präsentiert

Variable jump barriers in Monte-Carlo simulations of atom configuration changes in alloys

Kinetische Monte-Carlo (KMC) Simulationen sind ein wertvolles Hilfsmittel für das Studium der detaillierten Kinetik von Atomkonfigurationen in Legierungen. Diese Art von Simulation ist aber stark von den bereitgestellten Atomsprungfrequenzen abhängig. Basierend auf der Transition State Theorie werden diese durch eine zu überwindende Energiebarriere berechnet, die die Differenz zwischen einem Ausgangs- und einem Sattelpunktszustand darstellt. Während die Konfigurationsabhängigkeit des Ausgangszustandes normalerweise explizit berücksichtigt wird, wurde die Energie des Sattelpunktes üblicherweise auf einen fixen Wert gesetzt oder von der springenden Atomspezies abhängig gemacht. In dieser Arbeit wird ein verbesserter KMC Algorithmus mit variablen, also konfigurationsabhängigen, Sattelpunktslagen vorgestellt und für das L12 geordnete Modellsystem Ni3Al angewendet. Diese technologisch interessante intermetallische Verbindung dient als Beispiel für eine grosse Klasse an Materialen, bei denen ihr hochgeordneter Zustand zu günstigen Eigenschaften führt (Widerstand gegen Korrusion, ...). In diesem System muss ein Atom das seinen Platz mit einer Leerstelle tauscht durch ein 4-Atom-Fenster, gebildet von gemeinsamen Nachbarn, springen. Es stellt sich heraus, dass die Konfiguration dieses Fensters für die Höhe der Sprungbarriere ausschlaggebend ist. Aus diesem Grund wurde vollständiges Set von Energieprofilen aller möglichen Sprung- und Fenstertypen mit Hilfe des VASP Softwarepakets durch ab initio Berechnungen erstellt. Aus diesen Profilen wurden Energiebarrieren errechnet, die als Input für KMC Simulationen dienten. Damit wurde der Einfluss von variablen Barrierenhöhen auf die Kinetik studiert und mit der üblichen Formulierung mit konstantem Sattelpunkt verglichen. Es stellt sich heraus, dass konfigurationsabhängige Sattelpunktsenergien einen beträchtlichen Unterschied ausmachen, sowohl in der gesamten Kinetik, als auch in einer detailierten Sprungstatistik.Kinetic Monte-Carlo (KMC) simulation is a valuable tool for studying detailed atom configuration kinetics in alloys. This kind of simulation is, however, only as good as the single atom jump frequencies provided. Generally, invoking transition state theory, they are determined by an energy barrier to be surmounted, which is the difference between an initial state and a saddle point. While the configuration dependence of the initial state energy is usually treated explicitly, the saddle point energy was mostly set constant or made dependent on the atomic species in traditional treatments. In this thesis an improved KMC algorithm with variable, configuration dependent saddle point heights is introduced and demonstrated for the L12 ordered model system Ni3Al. This technologically interesting intermetallic compound acts as a role model for a wide class of materials where the highly ordered state leads to favorable properties (corrosion resistance, high-temperature strength,...). In this system an atom in order to exchange its position with a vacancy has to pass through a 4-atom window of common nearest neighbors. It turns out that the occupation of this window by either atom type is decisive for the height of the related barrier. Therefore a complete set of energy profiles for all possible jump types and window occupations was calculated ab inito employing the VASP code. Energy barriers derived from these profiles were used as an input for KMC simulations with the intention to test the influence of the variable saddle point formulation against the traditional fixed saddle point assumption. It is shown that configuration dependent saddle point energies make a considerable difference in both overall kinetics and detailed jump statistics

A Probabilistic Fatigue Strength Assessment in AlSi-Cast Material by a Layer-Based Approach

An advanced lightweight design in cast aluminium alloys features complexly shaped geometries with strongly varying local casting process conditions. This affects the local microstructure in terms of porosity grade and secondary dendrite arm spacing distribution. Moreover, complex service loads imply changing local load stress vectors within these components, evoking a wide range of highly stressed volumes within different microstructural properties per load sequence. To superimpose the effects of bulk and surface fatigue strength in relation to the operating load sequence for the aluminium alloy EN AC 46200, a layer-based fatigue assessment concept is applied in this paper considering a non-homogeneous distribution of defects within the investigated samples. The bulk fatigue property is now obtained by a probabilistic evaluation of computed tomography results per investigated layer. Moreover, the effect of clustering defects of computed tomography is studied according to recommendations from the literature, leading to a significant impact in sponge-like porosity layers. The highly stressed volume fatigue model is applied to computed tomography results. The validation procedure leads to a scattering of mean fatigue life from &minus;2.6% to 12.9% for the investigated layers, inheriting strongly varying local casting process conditions

Set-up of a Generalized Dataset for Crack-Closure-Mechanisms of Cast Steel

In components, crack propagation is subjected to crack-closure-mechanisms which affect the build-up of the relevant threshold stress intensity factor range during cyclic loading. As structural parts are exposed to service loads incorporating a variety of load ratios, a significant change of the long-crack threshold value occurs, leading to a severe stress ratio dependency of crack-closure-mechanisms. Thus, an extensive number of crack propagation experiments is required to gain statistically proven fracture mechanical parameters describing the build-up of closure effects as crack growth resistance curves.The article presents a generalized dataset to assess the formation of crack-closure-mechanisms of cast steel G21Mn5+N. Numerous crack propagation experiments utilizing single edge notched bending (SENB) sample geometries are conducted, incorporating alternate to tumescent stress ratios. The statistically derived, generalized crack growth resistance curve features the impact of closure effects on the crack propagation rate in a uniform manner. To extend the dataset to arbitrary load ratios, the long-crack threshold approach according to Newman is invoked. The generalized dataset for the cast steel G21Mn5+N is validated by analytical fracture mechanical calculations for the utilized SENB-sample geometries. Incorporating a modified NASGRO equation, a sound correlation of analytical and experimental crack propagation rates is observed. Moreover, the derived master crack propagation resistance curve is implemented as a user-defined script into a numerical crack growth calculation tool and supports a local, node--based numerical crack propagation study as demonstrated for a representative SENB-sample. Concluding, the derived dataset facilitates the calculation of fatigue life of crack-affected cast steel components subjected to arbitrary stress ratios