Hierarchical Crossover and Probability Landscapes of Genetic Operators

The time evolution of a simple model for crossover is discussed. A variant of this model with an improved exploration behavior in phase space is derived as a subset of standard one- and multi-point crossover operations. This model is solved analytically in the flat fitness case. Numerical simulations compare the way of phase space exploration of different genetic operators. In the case of a non-flat fitness landscape, numerical solutions of the evolution equations point out ways to estimate premature convergence.Comment: 11 pages, uuencoded postcript fil

Does Benford's law hold in economic research and forecasting?

First and higher order digits in data sets of natural and socio-economic processes often follow a distribution called Benford's law. This phenomenon has been used in many business and scientific applications, especially in fraud detection for financial data. In this paper, we analyse whether Benford's law holds in economic research and forecasting. First, we examine the distribution of leading digits of regression coefficients and standard errors in research papers, published in Empirica and Applied Economics Letters. Second, we analyse forecasts of GDP growth and CPI inflation in Germany, published in Consensus Forecasts. There are two main findings: The relative frequencies of the first and second digits in economic research are broadly consistent with Benford's law. In sharp contrast, the second digits of Consensus Forecasts exhibit a massive excess of zeros and fives, raising doubts on their information content. --Benford's Law,fraud detection,regression coefficients and standard errors,growth and inflation forecasts

Forecast quality and simple instrument rules: a real-time data approach

We start from the assertion that a useful monetary policy design should be founded on more realistic assumptions about what policymakers can know at the time when policy decisions have to be made. Since the Taylor rule – if used as an operational device - implies a forward looking behaviour, we analyze the reliability of the input information. We investigate the forecasting performance of OECD projections for GDP growth rates and inflation. We diagnose a much better forecasting record for inflation rates compared to GDP growth rates, which for most countries are almost uninformative at the time a Taylor rule should sensibly be applied. Using this data set, we find significant differences between Taylor rules estimated over revised data compared to real-time data. There is evidence that monetary policy seems to react more actively in real time than rules estimated over revised data suggest. Given the evidence of systematic errors in OECD forecasts, in a next step we attempt to correct for these forecast biases and check to which extent this can lower the errors in interest rate policy setting. An ex-ante simulation for the years 1991 to 2001 supports the proposal that correcting for forecast errors and biases based on an error model can lower the resulting policy error in interest rate setting for most countries under consideration. In addition we investigate to what extent structural changes in the policy reaction behaviour can be handled with moving instead of expanding samples. Our results point out that the information set available needs a careful examination when applied to instrument rules like those of the Taylor type. Limited forecast quality and significant data revisions recommend a more sophisticated handling of the dated information, for which we present an operational procedure that has the potential of reducing the risk of severe policy errors. --Monetary policy rules,economic forecasting,OECD,real-time data

Orbital frequencies in the carbonate sedimentary record: distorted by diagenesis?

The most important archive of Earth’s climate change through geologic history is the sedimentary rock record. Rhythmic sedimentary alternations are usually interpreted as a consequence of periodic variations in the orbital parameters of the Earth. This interpretation enables the application of cyclostratigraphy as a very precise chronometer, when based on the assumption that orbital frequencies are faithfully recorded in the sedimentary archive. However, there are numerous uncertainties with the application of this concept. Particularly in carbonates, sediment properties such as mineralogical composition and fossil associations are severely altered during post-depositional alteration (diagenesis). We here point out that the assumption of a 1:1 recording of orbital signals in many cases is questionable for carbonate rhythmites. We use computer simulations to show the effect of diagenetic overprint on records of orbital signals in the carbonate record. Such orbital signals may be distorted in terms of frequency, amplitude, and phase by diagenetic processes, and cycles not present in the insolation record may emerge. This questions the routine use of carbonate rhythmites for chronostratigraphic datin

A Large Along-Track Baseline Approach for Ground Moving Target Indication Using TanDEM-X

In the paper a new method for ground moving target indication (GMTI) using two satellites (i.e. the TerraSAR-X and the TanDEM-X satellite) together is presented. The along-track baseline between the satellites is chosen to be in the order of several kilometres, so that each satellite observes the same moving vehicles at different times in the order of one to several seconds. The proposed method allows the estimation of the ground velocity of the moving targets as well as the estimation of the broadside positions without the need of complex bistatic processing techniques

Role of the tetraquark in the chiral phase transition

We investigate the implications of a tetraquark field on chiral symmetry restoration at nonzero temperature. In order for the chiral phase transition to be cross-over, as shown by lattice QCD studies, a strong mixing between scalar quarkonium and tetraquark fields is required. This leads to a light ($\sim0.4$ GeV), predominantly tetraquark state, and a heavy ($\sim1.2$ GeV), predominantly quarkonium state in the vacuum, in accordance with recently advocated interpretations of spectroscopy data. The mixing even increases with temperature and leads to an interchange of the roles of the originally heavy, predominantly quarkonium state and the originally light, predominantly tetraquark state. Then, as expected, the scalar quarkonium is a light state when becoming degenerate in mass with the pion as chiral symmetry is restored at nonzero temperature.Comment: 4 pages, 2 figure

Wahrnehmung von Wirtsdüften durch Forstschädlinge : Vergleich zwischen einem Holzbrüter und einem Rindenbrüter

The blue pine wood borer (Phaenops cyanea) and the black pine sawyer beetle (Monochamus galloprovincialis) (Fig. 1) both are pests of the white pine (Pinus silvestris) and other Pinus species. Both insects have nearly the same demands regarding their breeding site. Larval development requires a fresh, unwilted inner bark. An infestation occurs on freshly cut trees or on trees suffering from stress (e.g. after dry seasons, loss of needles caused by feeding caterpillars or damage by forest fires). Phaenops cyanea detects susceptible pines by their volatile emissions (SCHÜTZ et al. 2004) and is able to infest the trees already at a low stress level. During feeding the larvae avoid the resin ducts of the tree and thus evade the oleoresin defence. The beetle is endemic in Europe and – under favourable climatic conditions – can cause substantial damage to pine forests. It is the most significant bark-breeding beetle of white pine in the lowlands of north-eastern Germany. Monochamus galloprovincialis is found in Europe and northern Africa. The larvae tend to a more copious feeding which makes them more susceptible to the oleoresin defence of the tree. Thus, M. galloprovincialis prefers trees that are weakened by a higher degree of stress. The economic damage caused by feeding of thebeetle is low. However, the beetle has gained a special attention of forest scientists because of its association with the nematode Bursaphelenchus xylophilus which is causing the pine wilt disease (PWD) in Pinus. The only outbreak of the PWD within Europe is limited to an area of 258.000 ha in Portugal. (MOTA et al. 1999).Die Forstschädlinge Phaenops cyanea (Coleoptera: Buprestidae) und Monochamus galloprovincialis (Coleoptera: Cerambycidae) befallen beide Kiefern (Pinus sylvestris), die geschwächt sind, z.B. durch Wasser-Stress. Die Larven von P. cyanea entwickeln sich in oder unter der Rinde, während Larven von M. galloprovincialis nach einem Fraß im Kambium des befallenen Baumes auch tief in das Holz eindringen. P. cyanea befällt bereits Bäume, die nur einem geringen Stress ausgesetzt waren, während M. galloprovincialis Bäume bevorzugt, die erheblich geschwächt oder bereits tot sind. Die vorliegende Studie soll anhand elektrophysiologischer Experimente untersuchen, welchen olfaktorischen Hinweisen die beiden Insekten bei ihrer Suche nach einem geeigneten Eiablageplatz folgen. Duftstoffe von Pinus sylvestris wurden auf Aktivkohle gesammelt und mit Gaschromatographie, Massenspektroskopie und Elektroantennographie untersucht (GC-MS/ EAD). Die stärksten Signale von P. cyanea traten im Retentionsindex-Bereich von 936 (α-Pinen) bis 1200 auf, wobei insbesondere bizyklische Terpene und Terpenoide wie α-Pinen, β-Pinen, 1,8-Cineol und trans- Verbenol detektiert wurden. M. galloprovincialis reagierte auf einen weiteren Bereich von Stoffen, ebenfalls beginnend mit α-Pinen, bis hin zu Stoffen mit einem Retentionsindex von ca. 1300. Es scheint eine spezifische Empfindlichkeit für monozyklische und azyklische Terpene und Terpenoide vorzuliegen, insbesondere für γ-Terpinen, Terpinolen, β-Myrcen und p-Cymen