Determination of the chiral pion-pion scattering parameters: a proposal

An explicitly crossing-symmetric decomposition of the pion-pion scattering amplitudes into low- and high-energy components is established. The high-energy components are entirely determined by absorptive parts at high energies. With the exception of the two leading-order parameters, all the parameters appearing in the one- and two-loop chiral amplitudes are determined by the high-energy components of the exact amplitudes.Comment: 14 pages plain latex, 2 figures, uuencoded, tarred and compresse

Pay-as-you-go data integration for bio-informatics

Scientific research in bio-informatics is often data-driven and supported by numerous biological databases. A biological database contains factual information collected from scientific experiments and computational analyses about areas including genomics, proteomics, metabolomics, microarray gene expression and phylogenetics. Information contained in biological databases includes gene function, structure, localization (both cellular and chromosomal), clinical effects of mutations as well as similarities of biological sequences and structures. In a growing number of research projects, bio-informatics researchers like to ask combined ques- tions, i.e., questions that require the combination of information from more than one database. We have observed that most bio-informatics papers do not go into detail on the integration of different databases. It has been observed that roughly 30% of all tasks in bio-informatics workflows are data transformation tasks, a lot of time is used to integrate these databases (shown by [1]). As data sources are created and evolve, many design decisions made by their creators. Not all of these choices are documented. Some of such choices are made implicitly based on experience or preference of the creator. Other choices are mandated by the purpose of the data source, as well as inherent data quality issues such as imprecision in measurements, or ongoing scientific debates. Integrating multiple data sources can be difficult. We propose to approach the time-consuming problem of integrating multiple biological databases through the principles of ‘pay-as-you-go’ and ‘good-is-good-enough’. By assisting the user in defin- ing a knowledge base of data mapping rules, schema alignment, trust information and other evidence we allow the user to focus on the work, and put in as little effort as is necessary for the integration to serve the purposes of the user. By using user feedback on query results and trust assessments, the integration can be improved upon over time. The research will be guided by a set of use cases. As the research is in its early stages, we have determined three use cases: Homologues, the representation and integration of groupings. Homology is the relationship between two characteristics that have descended, usually with divergence, from a common ancestral characteristic. A characteristic can be any genic, structural or behavioural feature of an organism Metabolomics integration, with a focus on the TCA cycle. The TCA cycle (also known as the citric acid cycle, or Krebs cycle) is used by aerobic organism to generate energy from the oxidation of carbohydrates, fats and proteins. Bibliography integration and improvement, the correction and expansion of citation databases. [1] I. Wassink. Work flows in life science. PhD thesis, University of Twente, Enschede, January 2010

No WIMP Mini-Spikes in Dwarf Spheroidal Galaxies

The formation of black holes inevitably affects the distribution of dark and baryonic matter in their vicinity, leading to an enhancement of the dark matter density, called spike, and if dark matter is made of WIMPs, to a strong enhancement of the dark matter annihilation rate. Spikes at the center of galaxies like the Milky Way are efficiently disrupted by baryonic processes, but mini-spikes can form and survive undisturbed at the center of dwarf spheroidal galaxies. We show that Fermi LAT satellite data allow to set very stringent limits on the existence of mini-spikes in dwarf galaxies: for thermal WIMPs with mass between 100 GeV and 1 TeV, we obtain a maximum black hole mass between 100 and 1000 $M_\odot$, ruling out black holes masses extrapolated from the M-{\sigma} relationship in a large region of the parameter space. We also performed Monte Carlo simulations of merger histories of black holes in dwarf spheroidals in a scenario where black holes form from the direct collapse of primordial gas in early halos, and found that this specific formation scenario is incompatible at the 84% CL with dark matter being in the form of thermal WIMPs.Comment: 23 pages, 6 figures, 2 tables; typos corrected and references added; version submitted to JCA

Thecomposition of semi finished inventories at a solid board plant

A solid board factory produces rectangular sheets of cardboard in two different formats, namely large formats and small formats. The production process consists of two stages separated by an inventory point. In the first stage a cardboard machine produces the large formats. In the second stage a part of the large formats is cut into small formats by a separate rotary cut machine. Due to very large setup times, technical restrictions, and trim losses, the cardboard machine is not able to produce these small formats. The company follows two policies to satisfy customer demands for rotary cut format orders. When the company applies the first policy, then for each customer order an ‘optimal’ large format (with respect to trim loss) is determined and produced on the cardboard machine. In case of the second policy, a stock of a restricted number of large formats is determined in such a way that the expected trim loss is minimal. The rotary cut format order then uses the most suitable standard large format from the stock. Currently, the dimensions of the standard large formats in the semi finished inventory are based on intuitive motives, with an accent on minimizing trim losses. From the trim loss perspective it is most efficient to produce each rotary cut format from a specific large format. On the other hand, if there is only one large format in each caliper, the variety is minimal, but the trim loss might be inacceptably high. On average, the first policy results in a lower trim loss. In order to make efficiently use of the two machines and to meet customer’s due times the company applies both policies. In this paper we concentrate on the second policy, taking into account the various objectives and restrictions of the company. The purpose of the company is to have not too many different types of large formats and an acceptable amount of trim loss. The problem is formulated as a minimum clique covering problem with alternatives (MCCA), which is presumed to be NP-hard. We solve the problem by using an appropriate heuristic, which is built into a decision support system. Based on a set of real data, the actual composition of semi finished inventories is determined. The paper concludes with computational experiments.

Optical Continuum and Emission-Line Variability of Seyfert 1 Galaxies

We present the light curves obtained during an eight-year program of optical spectroscopic monitoring of nine Seyfert 1 galaxies: 3C 120, Akn 120, Mrk 79, Mrk 110, Mrk 335, Mrk 509, Mrk 590, Mrk 704, and Mrk 817. All objects show significant variability in both the continuum and emission-line fluxes. We use cross-correlation analysis to derive the sizes of the broad Hbeta-emitting regions based on emission-line time delays, or lags. We successfully measure time delays for eight of the nine sources, and find values ranging from about two weeks to a little over two months. Combining the measured lags and widths of the variable parts of the emission lines allows us to make virial mass estimates for the active nucleus in each galaxy. The virial masses are in the range 10^{7-8} solar masses.Comment: 24 pages, 16 figures. Accepted for publication in Ap

Chiral two-loop pion-pion scattering parameters from crossing-symmetric constraints

Constraints on the parameters in the one- and two-loop pion-pion scattering amplitudes of standard chiral perturbation theory are obtained from explicitly crossing-symmetric sum rules. These constraints are based on a matching of the chiral amplitudes and the physical amplitudes at the symmetry point of the Mandelstam plane. The integrals over absorptive parts appearing in the sum rules are decomposed into crossing-symmetric low- and high-energy components and the chiral parameters are finally related to high-energy absorptive parts. A first application uses a simple model of these absorptive parts. The sensitivity of the results to the choice of the energy separating high and low energies is examined with care. Weak dependence on this energy is obtained as long as it stays below ~560 MeV. Reliable predictions are obtained for three two-loop parameters.Comment: 23 pages, 4 figures in .eps files, Latex (RevTex), our version of RevTex runs under Latex2.09, submitted to Phys. Rev. D,minor typographical corrections including the number at the end of the abstract, two sentences added at the end of Section 5 in answer to a referee's remar

PayDIBI: Pay-as-you-go data integration for bioinformatics

Background: Scientific research in bio-informatics is often data-driven and supported by biolog- ical databases. In a growing number of research projects, researchers like to ask questions that require the combination of information from more than one database. Most bio-informatics papers do not detail the integration of different databases. As roughly 30% of all tasks in workflows are data transformation tasks, database integration is an important issue. Integrating multiple data sources can be difficult. As data sources are created, many design decisions are made by their creators. Methods: Our research is guided by two use cases: homologues, the representation and integration of groupings; metabolomics integration, with a focus on the TCA cycle. Results: We propose to approach the time consuming problem of integrating multiple biological databases through the principles of ‘pay-as-you-go’ and ‘good-is-good-enough’. By assisting the user in defining a knowledge base of data mapping rules, trust information and other evidence we allow the user to focus on the work, and put in as little effort as is necessary for the integration. Through user feedback on query results and trust assessments, the integration can be improved upon over time. Conclusions: We conclude that this direction of research is worthy of further exploration