Research accomplished at the Knowledge Based Systems Lab: IDEF3, version 1.0

An overview is presented of the foundations and content of the evolving IDEF3 process flow and object state description capture method. This method is currently in beta test. Ongoing efforts in the formulation of formal semantics models for descriptions captured in the outlined form and in the actual application of this method can be expected to cause an evolution in the method language. A language is described for the representation of process and object state centered system description. IDEF3 is a scenario driven process flow modeling methodology created specifically for these types of descriptive activities

Observable Dependent Quasi-Equilibrium in Slow Dynamics

We present examples demonstrating that quasi-equilibrium fluctuation-dissipation behavior at short time differences is not a generic feature of systems with slow non-equilibrium dynamics. We analyze in detail the non-equilibrium fluctuation-dissipation ratio X(t,tw) associated with a defect-pair observable in the Glauber-Ising spin chain. It turns out that $X \neq 1$ throughout the short-time regime and in particular X(tw,tw) = 3/4 for $tw \to \infty$. The analysis is extended to observables detecting defects at a finite distance from each other, where similar violations of quasi-equilibrium behaviour are found. We discuss our results in the context of metastable states, which suggests that a violation of short-time quasi-equilibrium behavior could occur in general glassy systems for appropriately chosen observables.Comment: 17 pages, 5 figures; substantially improved version of cond-mat/040571

Dynamic heterogeneities in critical coarsening: Exact results for correlation and response fluctuations in finite-sized spherical models

We study dynamic heterogeneities in the out-of-equilibrium coarsening dynamics of the spherical ferromagnet after a quench from infinite temperature to its critical point. A standard way of probing such heterogeneities is by monitoring the fluctuations of correlation and susceptibility, coarse-grained over mesoscopic regions. We discuss how to define fluctuating coarse-grained correlations (C) and susceptibilities (Chi) in models where no quenched disorder is present. Our focus for the spherical model is on coarse-graining over the whole volume of $N$ spins, which requires accounting for N^{-1/2} non-Gaussian fluctuations of the spin. The latter are treated as a perturbation about the leading order Gaussian statistics. We obtain exact results for these quantities, which enable us to characterise the joint distribution of C and Chi fluctuations. We find that this distribution is qualitatively different, even for equilibrium above criticality, from the spin-glass scenario where C and Chi fluctuations are linked in a manner akin to the fluctuation-dissipation relation between the average C and Chi. Our results show that coarsening at criticality is clearly heterogeneous for d>4 and suggest that, as in other glassy systems, there is a well-defined timescale on which fluctuations across thermal histories are largest. Surprisingly, however, neither this timescale nor the amplitude of the heterogeneities increase with the age of the system, as would be expected from the growing correlation length. For d<4, the strength of the fluctuations varies on a timescale proportional to the age of the system; the corresponding amplitude also grows with age, but does not scale with the correlation volume as might have been expected naively.Comment: 39 pages, 9 figures, version for publication in J. Stat. Mech. Shortened by cutting all technical details in section 6, with minor corrections elsewher

Rapid Formation of Supermassive Black Hole Binaries in Galaxy Mergers with Gas

Supermassive black holes (SMBHs) are a ubiquitous component of the nuclei of galaxies. It is normally assumed that, following the merger of two massive galaxies, a SMBH binary will form, shrink due to stellar or gas dynamical processes and ultimately coalesce by emitting a burst of gravitational waves. However, so far it has not been possible to show how two SMBHs bind during a galaxy merger with gas due to the difficulty of modeling a wide range of spatial scales. Here we report hydrodynamical simulations that track the formation of a SMBH binary down to scales of a few light years following the collision between two spiral galaxies. A massive, turbulent nuclear gaseous disk arises as a result of the galaxy merger. The black holes form an eccentric binary in the disk in less than a million years as a result of the gravitational drag from the gas rather than from the stars.Comment: Accepted for publication in Science, 40 pages, 7 figures, Supplementary Information include

Experimental constraints on the γ\gamma-ray strength function in 90^{90}Zr using partial cross sections of the 89^{89}Y(p,γ\gamma)90^{90}Zr reaction

Partial cross sections of the $^{89}$Y(p,$\gamma$)$^{90}$Zr reaction have been measured to investigate the $\gamma$-ray strength function in the neutron-magic nucleus $^{90}$Zr. For five proton energies between $E_p=3.65$ MeV and $E_p=4.70$ MeV, partial cross sections for the population of seven discrete states in $^{90}$Zr have been determined by means of in-beam $\gamma$-ray spectroscopy. Since these $\gamma$-ray transitions are dominantly of $E1$ character, the present measurement allows an access to the low-lying dipole strength in $^{90}$Zr. A $\gamma$-ray strength function based on the experimental data could be extracted, which is used to describe the total and partial cross sections of this reaction by Hauser-Feshbach calculations successfully. Significant differences with respect to previously measured strength functions from photoabsorption data point towards deviations from the Brink-Axel hypothesis relating the photo-excitation and de-excitation strength functions.Comment: 5 pages, 5 figure

Aging in One-Dimensional Coagulation-Diffusion Processes and the Fredrickson-Andersen Model

We analyse the aging dynamics of the one-dimensional Fredrickson-Andersen (FA) model in the nonequilibrium regime following a low temperature quench. Relaxation then effectively proceeds via diffusion limited pair coagulation (DLPC) of mobility excitations. By employing a familiar stochastic similarity transformation, we map exact results from the free fermion case of diffusion limited pair annihilation to DLPC. Crucially, we are able to adapt the mapping technique to averages involving multiple time quantities. This relies on knowledge of the explicit form of the evolution operators involved. Exact results are obtained for two-time correlation and response functions in the free fermion DLPC process. The corresponding long-time scaling forms apply to a wider class of DLPC processes, including the FA model. We are thus able to exactly characterise the violations of the fluctuation-dissipation theorem (FDT) in the aging regime of the FA model. We find nontrivial scaling forms for the fluctuation-dissipation ratio (FDR) X = X(tw/t), but with a negative asymptotic value X = -3*pi/(6*pi - 16) = -3.307. While this prevents a thermodynamic interpretation in terms of an effective temperature, it is a direct consequence of probing FDT with observables that couple to activated dynamics. The existence of negative FDRs should therefore be a widespread feature in non mean-field systems.Comment: 39 pages, 4 figure

Venture Capital in Japan: A Financial Instrument Supporting the Innovativeness of the Japanese Economy

Two factors: First, the relatively small number of new companies as well as the number of companies subject to liquidation over the year ("firm turnover") in Japan, and second, the insignificant prestige associated with the profession of entrepreneur do not foster growth in the dynamics of this form of financing ventures. The cited indicator for Japan in among the lowest in comparison with other highly developed countries1, while the profession of entrepreneur is not the foremost dream of college graduates. They would much rather prefer realizing their professional careers as members of the government bureaucracy or employees of a major corporation2. However, this mindset is slowly changing, if for no other reason then, in spite of popular conviction, because most small companies are not established during periods of prosperity, but near the end of the downward phase of the economic cycle. That is exactly the phase Japan has been dealing with for several years now. Young, creative people, recruited from the unemployed, are seeking self-employment, using all possible opportunities embedded in the "again starting up" machinery of the economy.Dwa czynniki: pierwszy - stosunkowo mała liczba nowych firm, a także firm likwidowanych w skali roku ("firm turnover") w Japonii oraz drugi - niewielki prestiż, jakim cieszy się zawód przedsiębiorcy, nie sprzyjają dynamizacji omawianej formy finansowania przedsięwzięć. Cytowany wskaźnik, dla Japonii należy do najniższych w porównaniu z innymi krajami wysoko rozwiniętymi (Grabowiecki 2000), zaś profesja przedsiębiorcy nie jest szczytem marzeń ludzi po studiach. Znacznie bardziej chcieliby oni swoją karierę zawodową realizować jako członkowie rządowej biurokracji lub pracownicy dużej korporacji (Corver 2008, s. 2). Ta świadomość ulega jednak stopniowej zmianie, chociażby dlatego, że wbrew popularnym przekonaniom, większość niewielkich przedsiębiorstw, powstaje nie w okresie prosperity, lecz pod koniec spadkowej fazy cyklu koniunkturalnego. Z taką fazą mamy do czynienia w Japonii od paru lat. Młodzi, kreatywni ludzie, rekrutujący się z bezrobotnych, poszukują samozatrudnienia, wykorzystują wszelakie szanse, tkwiące w "ruszającej na powrót" maszynerii gospodark (Yonekura, Lynskey 2003, s. 11)

Hybrid confinement of optical and mechanical modes in a bullseye optomechanical resonator

Optomechanical cavities have proven to be an exceptional tool to explore fundamental and technological aspects of the interaction between mechanical and optical waves. Such interactions strongly benefit from cavities with large optomechanical coupling, high mechanical and optical quality factors, and mechanical frequencies larger than the optical mode linewidth, the so called resolved sideband limit. Here we demonstrate a novel optomechanical cavity based on a disk with a radial mechanical bandgap. This design confines light and mechanical waves through distinct physical mechanisms which allows for independent control of the mechanical and optical properties. Our device design is not limited by unique material properties and could be easily adapted to allow large optomechanical coupling and high mechanical quality factors with other promising materials. Finally, our demonstration is based on devices fabricated on a commercial silicon photonics facility, demonstrating that our approach can be easily scalable.Comment: 16 pages, 11 figure

Observability of Forming Planets and their Circumplanetary Disks I. -- Parameter Study for ALMA

We present mock observations of forming planets with ALMA. The possible detections of circumplanetary disks (CPDs) were investigated around planets of Saturn, 1, 3, 5, and 10 Jupiter-masses that are placed at 5.2 AU from their star. The radiative, three dimensional hydrodynamic simulations were then post-processed with RADMC3D and the ALMA Observation Simulator. We found that even though the CPDs are too small to be resolved, they are hot due to the accreting planet in the optically thick limit, therefore the best chance to detect them with continuum observations in this case is at the shortest ALMA wavelengths, such as Band 9 (440 microns). Similar fluxes were found in the case of Saturn and Jupiter-mass planets, as for the 10 $\mathrm{M_{Jup}}$ gas-giant, due to temperature weighted optical depth effects: when no deep gap is carved, the planet region is blanketed by the optically thick circumstellar disk leading to a less efficient cooling there. A test was made for a 52 AU orbital separation, showed that optically thin CPDs are also detectable in band 7 but they need longer integration times ($>$5hrs). Comparing the gap profiles of the same simulation at various ALMA bands and the hydro simulation confirmed that they change significantly, first because the gap is wider at longer wavelengths due to decreasing optical depth; second, the beam convolution makes the gap shallower and at least 25% narrower. Therefore, caution has to be made when estimating planet masses based on ALMA continuum observations of gaps.Comment: Accepted for publication at MNRAS. Typos are corrected since previous version. 11 pages, 5 tables, 4 figure