Multivariate side-band subtraction using probabilistic event weights

A common situation in experimental physics is to have a signal which can not be separated from a non-interfering background through the use of any cut. In this paper, we describe a procedure for determining, on an event-by-event basis, a quality factor ($Q$-factor) that a given event originated from the signal distribution. This procedure generalizes the "side-band" subtraction method to higher dimensions without requiring the data to be divided into bins. The $Q$-factors can then be used as event weights in subsequent analysis procedures, allowing one to more directly access the true spectrum of the signal.Comment: 17 pages, 9 figure

Acceptance conditions in automated negotiation

In every negotiation with a deadline, one of the negotiating parties has to accept an offer to avoid a break off. A break off is usually an undesirable outcome for both parties, therefore it is important that a negotiator employs a proficient mechanism to decide under which conditions to accept. When designing such conditions one is faced with the acceptance dilemma: accepting the current offer may be suboptimal, as better offers may still be presented. On the other hand, accepting too late may prevent an agreement from being reached, resulting in a break off with no gain for either party. Motivated by the challenges of bilateral negotiations between automated agents and by the results and insights of the automated negotiating agents competition (ANAC), we classify and compare state-of-the-art generic acceptance conditions. We focus on decoupled acceptance conditions, i.e. conditions that do not depend on the bidding strategy that is used. We performed extensive experiments to compare the performance of acceptance conditions in combination with a broad range of bidding strategies and negotiation domains. Furthermore we propose new acceptance conditions and we demonstrate that they outperform the other conditions that we study. In particular, it is shown that they outperform the standard acceptance condition of comparing the current offer with the offer the agent is ready to send out. We also provide insight in to why some conditions work better than others and investigate correlations between the properties of the negotiation environment and the efficacy of acceptance condition

Microstructural and environmental effects on stress corrosion and corrosion fatigue of 7075 aluminum alloy

The design and development of high performance structural materials requires a thorough understanding of the relationship between environment, mechanical stresses, microstructure, and properties. The corrosion and fatigue behavior of aluminum alloys is greatly influenced by environment and precipitate structure. A comprehensive, mechanistic understanding of the role of environment on cyclic fatigue of Al alloys is needed. The relationship between environmental and mechanical effects is not well understood. The driving force at the crack tip is clearly a combination of chemical and mechanical processes operating together. A synergy between these processes is also present. In this talk, the role of moisture on stress corrosion and corrosion-fatigue of 7075 Al alloy will be presented. Rolled 7075 Al alloy was heat-treated to underaged, peak-aged, and overaged conditions. To investigate the effects of corrosion and fatigue on peak-aged 7075 aluminum alloy, corroded samples were tested via in situ x-Ray tomography. The samples were mechanically polished, then soaked in covered 3.5 wt.% NaCl for fifteen days to allow for significant corrosion to occur. Then, they were fatigue tested in situ in 3.5 wt.% NaCl using synchrotron x-ray tomography to analyze the fatigue crack initiation and growth characteristics. Hydrogen bubbles were observed between the sample and the fluid upon crack initiation, indicating chemical changes in the sample during in situ corrosion fatigue. The effect of oxide layers forming during corrosion and 2nd phase inclusions, on fatigue initiation and propagation, will be discussed. The microstructure and morphology of the fracture surfaces were examined by scanning electron microscopy (SEM) and correlated with the crack growth behavior. The crack initiation, growth, and damage were also quantified by sophisticated three dimensional (3D) in situ x-ray synchrotron tomography technique. This technique provided interesting insights into the onset of crack initiation and growt

The causal relationship between sexual selection and sexual size dimorphism in marine gastropods

Sexual size dimorphism is widespread among dioecious species, but its underlying driving forces are often complex. A review of sexual size dimorphism in marine gastropods revealed two common patterns: first, sexual size dimorphism, with females being larger than males, and, second, females being larger than males in mating pairs. Both patterns suggest sexual selection and sexual size dimorphism are causally related. To test this hypothesis, we investigated, first, mechanisms driving sexual selection on size in three congeneric marine gastropods with different degrees of sexual size dimorphism, and, second, the correlation between male/female sexual selection and sexual size dimorphism across several marine gastropod species. Male mate choice via mucus trail following (as evidence of sexual selection) was found during the mating process in all three congeneric species, even though not all species showed sexual size dimorphism. There was also a significant and strong negative correlation between female sexual selection and sexual size dimorphism across 16 cases from seven marine gastropod species. These results suggest that sexual selection does not drive sexual size dimorphism. There was, however, evidence of males utilizing a similar mechanism to choose mates (i.e. selecting a female slightly larger than their own size) which may be widespread among gastropods, and, in tandem with sexual size dimorphism varying between species, provides a plausible explanation of the mating patterns observed in marine gastropods

Young star clusters in M31

In our study of M31's globular cluster system with MMT/Hectospec, we have obtained high-quality spectra of 85 clusters with ages less than 1 Gyr. With the exception of Hubble V, the young cluster in NGC 205, we find that these young clusters have kinematics and spatial distribution consistent with membership in M31's young disk. Preliminary estimates of the cluster masses and structural parameters, using spectroscopically derived ages and HST imaging, confirms earlier suggestions that M31 has clusters similar to the LMC's young populous clusters.Comment: 4 pages, 1 figure, contributed talk at "Galaxies in the Local Volume" conference in Sydney, July 200

In situ three-dimensional study of corrosion fatigue crack initiation and growth of corroded 7075 aluminum alloys

Corrosion fatigue crack initiation in aluminum alloys can have significant effects on part life. An improved understanding of the mechanisms governing corrosion and corrosion fatigue damage of Al alloys is necessary. Alloy design and environmental chemistry have significant effects on corrosion fatigue crack initiation and growth. Influential alloy design features include alloy chemistry, precipitate structure, and grain structure. Environmental factors such as environmental chemistry and preexisting corrosion damage can also effect the corrosion fatigue behavior of the alloys. To investigate the effects of environment and precipitate size on corrosion fatigue of aluminum alloys, the in situ corrosion fatigue testing of corroded peak-aged and overaged 7075 Al alloys in 3.5 wt% NaCl solution will be presented. For this study, rolled 7075 Al alloy was heat-treated to peak-aged, overaged, and highly overaged conditions. The samples were machined, mechanically polished, masked, and then soaked in 3.5 wt.% NaCl solution for fifteen days to yield significant corrosion damage in a region of interest. The corroded specimens were fatigue tested in situ in 3.5 wt.% NaCl using synchrotron X-ray tomography to gain three dimensional information regarding fatigue crack initiation and growth characteristics. Hydrogen bubbles were observed within the crack during propagation, indicating chemical changes in the sample during corrosion fatigue. The crack initiation, growth, and bubble evolution were quantified and discussed. A relationship was observed between the bubble volume and crack surface area as the test progressed, which suggested an effect from stress at the crack tip. Ultimately, this in situ study provided new insights regarding the localized processes occurring during the corrosion fatigue cracking of aluminum alloys which previous post-mortem and two dimensional studies were unable to discover

Waste-derived activated carbons for control of nitrogen oxides

Activated carbons were produced from waste and investigated for their efficiency for the removal of mono-nitrogen oxides (NOx) in simulated flue gases at a low temperature. The wastes used were waste biomass (date seeds), processed municipal solid waste in the form of refuse-derived fuel and waste tyres. The morphology, porous texture and surface chemistry of the prepared activated carbons were evaluated by scanning electron microscopy, energy-dispersive X-ray spectrometry, nitrogen adsorption and Boehm titration, and were compared with several commercial activated carbons. The carbons were then investigated in terms of their use in adsorbing NOx at a low temperature. The waste-derived activated carbons had NOx adsorption efficiencies at 50°C which were between 50 and 70% of those achieved for the commercial activated carbons. Increasing the adsorption temperature from 25 to 100°C significantly reduced nitrogen oxide (NO) adsorption. It was also shown that the NO adsorption efficiency depends on the porous structure, particularly the presence of micropores in the activated carbon, but to a lesser extent on the surface area of the carbons and acid–base surface groups on the carbon surface

Gravitation and inertia; a rearrangement of vacuum in gravity

We address the gravitation and inertia in the framework of 'general gauge principle', which accounts for 'gravitation gauge group' generated by hidden local internal symmetry implemented on the flat space. We connect this group to nonlinear realization of the Lie group of 'distortion' of local internal properties of six-dimensional flat space, which is assumed as a toy model underlying four-dimensional Minkowski space. The agreement between proposed gravitational theory and available observational verifications is satisfactory. We construct relativistic field theory of inertia and derive the relativistic law of inertia. This theory furnishes justification for introduction of the Principle of Equivalence. We address the rearrangement of vacuum state in gravity resulting from these ideas.Comment: 17 pages, no figures, revtex4, Accepted for publication in Astrophys. Space Sc

Research of Gravitation in Flat Minkowski Space

In this paper it is introduced and studied an alternative theory of gravitation in flat Minkowski space. Using an antisymmetric tensor, which is analogous to the tensor of electromagnetic field, a non-linear connection is introduced. It is very convenient for studying the perihelion/periastron shift, deflection of the light rays near the Sun and the frame dragging together with geodetic precession, i.e. effects where angles are involved. Although the corresponding results are obtained in rather different way, they are the same as in the General Relativity. The results about the barycenter of two bodies are also the same as in the General Relativity. Comparing the derived equations of motion for the $n$-body problem with the Einstein-Infeld-Hoffmann equations, it is found that they differ from the EIH equations by Lorentz invariant terms of order $c^{-2}$.Comment: 28 page