Firm Size Distribution and Returns to Scale. Non-Parametric Frontier Estimates from Italian Manufacturing

This paper explores the relationship between firm size distribution and technology. We analyse firm technology across selected manufacturing industries by means of a non-parametric production analysis, the Free Disposal Hull approach (Deprins et al., 1984; Kerstens and Vanden Eeckaut, 1999) and appraise the links between size and scale elasticity, finding a clear inverse relationship. Building on this result, we inquire whether the shape of the firm size distribution is related to a particular pattern of scale elasticities. We rely on the Zipf Plot (Stanley et al., 1995) of the Pareto IV distribution, which is concave up to a given threshold, and then approximately linear. Firms in the concave part of the plot are overwhelmingly found to experience increasing returns to scale. On the contrary, firms in the linear part are mainly characterised by constant returns to scale.

Stochastic modeling of a serial killer

We analyze the time pattern of the activity of a serial killer, who during twelve years had murdered 53 people. The plot of the cumulative number of murders as a function of time is of "Devil's staircase" type. The distribution of the intervals between murders (step length) follows a power law with the exponent of 1.4. We propose a model according to which the serial killer commits murders when neuronal excitation in his brain exceeds certain threshold. We model this neural activity as a branching process, which in turn is approximated by a random walk. As the distribution of the random walk return times is a power law with the exponent 1.5, the distribution of the inter-murder intervals is thus explained. We illustrate analytical results by numerical simulation. Time pattern activity data from two other serial killers further substantiate our analysis

Analisis Sebaran Vegetasi Pasak Bumi (Eurycoma Longifolia Jack.) Di Hutan Larangan Adat Kenegerian Rumbio Kabupaten Kampar Analysis of Distribution of Vegetation

The Forest Reserve of Kenegerian Rumbio Kampar District is one that holds a lot of conservation of germplasm one Eurycoma longifolia Jack, information regarding the distribution pattern of the forest Eurycoma longifolia Jack in the Forest Reserve of Kenegerian Rumbio was limited. This study aims to determine the analysis of vegetation and distribution patterns of Eurycoma longifolia Jack in Panoghan zone, Naghao Koto zone, and Sialang Layang zone from Forest Reserve of Kenegerian Rumbio. This study using purposive sampling method.The observation plot is made in square plot which plot size was 20 x 20 m for tree level and 10 x 10 m for the poles. The results of this study indicate that the analysis of vegetation reaches its maximum value outcome important value index is 300%. Distribution pattern of Eurycoma longifolia Jack were clumped with Morisita Index value > 1. Eurycoma longifolia Jack clumped distribution petterns caused by Eurycoma longifolia Jack seeds grow not far from the mother tree, Eurycoma longifolia Jack tolerant shade tree canopies, and by factors of edafik

Correlation methods for the analysis of X-ray polarimetric signals

X-ray polarimetric measurements are based on studying the distribution of the directions of scattered photons or photoelectrons and on the search of a sinusoidal modulation with a period of {\pi}. We developed two tools for investigating these angular distributions based on the correlations between counts in phase bins separated by fixed phase distances. In one case we use the correlation between data separated by half of the bin number (one period) which is expected to give a linear pattern. In the other case, the scatter plot obtained by shifting by 1/8 of the bin number (1/4 of period) transforms the sinusoid in a circular pattern whose radius is equal to the amplitude of the modulation. For unpolarized radiation these plots are reduced to a random point distribution centred at the mean count level. This new methods provide direct visual and simple statistical tools for evaluating the quality of polarization measurements and for estimating the polarization parameters. Furthermore they are useful for investigating distortions due to systematic effects

Numerical Simulation of Vortex Crystals and Merging in N-Point Vortex Systems with Circular Boundary

In two-dimensional (2D) inviscid incompressible flow, low background vorticity distribution accelerates intense vortices (clumps) to merge each other and to array in the symmetric pattern which is called ``vortex crystals''; they are observed in the experiments on pure electron plasma and the simulations of Euler fluid. Vortex merger is thought to be a result of negative ``temperature'' introduced by L. Onsager. Slight difference in the initial distribution from this leads to ``vortex crystals''. We study these phenomena by examining N-point vortex systems governed by the Hamilton equations of motion. First, we study a three-point vortex system without background distribution. It is known that a N-point vortex system with boundary exhibits chaotic behavior for N\geq 3. In order to investigate the properties of the phase space structure of this three-point vortex system with circular boundary, we examine the Poincar\'e plot of this system. Then we show that topology of the Poincar\'e plot of this system drastically changes when the parameters, which are concerned with the sign of ``temperature'', are varied. Next, we introduce a formula for energy spectrum of a N-point vortex system with circular boundary. Further, carrying out numerical computation, we reproduce a vortex crystal and a vortex merger in a few hundred point vortices system. We confirm that the energy of vortices is transferred from the clumps to the background in the course of vortex crystallization. In the vortex merging process, we numerically calculate the energy spectrum introduced above and confirm that it behaves as k^{-\alpha},(\alpha\approx 2.2-2.8) at the region 10^0<k<10^1 after the merging.Comment: 30 pages, 11 figures. to be published in Journal of Physical Society of Japan Vol.74 No.

Kepadatan Dan Distribusi Keong Mas (Pomacea Canaliculata) Di Saluran Irigasi Bendungan Batang Samo Desa Suka Maju Kabupaten Rokan Hulu

Study about density and distribution pattern of golden snail (Pomacea canaliculata) at irigation Batang Samo Suka Maju Village Rokan Hulu Regency has been conducted in August to December 2014 with survey method and purposiv random sampling tecniques by used 1x1 meters squared plot and thrown at three observation stations as much as 50 hurl times. The results shown that density P.canaliculata subsequently in three station is 12,72 individuals/m2 in station 1, followed 4,92 individuals/m2 in station 2 and followed 8,4 individuals /m2 in station 3. Distribution pattern of P. canaliculata in three observation was grouped

Gas Dynamics in the Milky Way: Second Pattern Speed and Large-Scale Morphology

We present new gas flow models for the Milky Way inside the solar circle. To this end we use SPH simulations in gravitational potentials determined from the NIR luminosity distribution (including spiral arms) which are based on the COBE/DIRBE maps. Gas flows in models which include massive spiral arms clearly match the observed 12CO lvplot better than if the potential does not include spiral structure. Besides single pattern speed models we investigate models with separate pattern speeds for the bar and spiral arms. The most important difference is that in the latter case the gas spiral arms go through the bar corotation region, keeping the gas aligned with the arms there. In the (l,v) plot this results in characteristic regions which appear to be nearly void of gas.In single pattern speed models these regions are filled with gas because the spiral arms dissolve in the bar corotation region. Comparing with the 12CO data we find evidence for separate pattern speeds in the Milky Way.From a series of models the preferred range for the bar pattern speed is Om_p=60\pm5 /Gyr, corresponding to corotation at 3.4\pm0.3kpc. The spiral pattern speed is less well constrained, but our preferred value is Om_sp\approx 20 /Gyr. A further series of gas models is computed for different bar angles, using separately determined luminosity models and gravitational potentials in each case. We find acceptable gas models for 20<=\phibar<=25. The model with (\phibar=20, Om_p=60 /Gyr, Om_sp=20 /Gyr) gives an excellent fit to the spiral arm ridges in the observed (l,v) plot.Comment: Paper accepted for publication in MNRAS. The paper contains many figures. These are not included in the version available here to save download time. A full version can be downloaded from http://latour.stochastik.math.uni-goettingen.de/~downloads/sphpaper.ps.g

Beta-diversity of Central European forests decreases along an elevational gradient due to the variation in local community assembly processes

Beta-diversity has been repeatedly shown to decline with increasing elevation, but the causes of this pattern remain unclear, partly because they are confounded by coincident variation in alpha- and gamma-diversity. We used 8,795 forest vegetation-plot records from the Czech National Phytosociological Database to compare the observed patterns of beta diversity to null-model expectations (beta-deviation) controlling for the effects of alpha- and gamma-diversity. We tested whether \b{eta}-diversity patterns along a 1,200 m elevation gradient exclusively depend on the effect of varying species pool size, or also on the variation of the magnitude of community assembly mechanisms determining the distribution of species across communities (e.g., environmental filtering, dispersal limitation). The null model we used is a novel extension of an existing null-model designed for presence/absence data and was specifically designed to disrupt the effect of community assembly mechanisms, while retaining some key features of observed communities such as average species richness and species abundance distribution. Analyses were replicated in ten subregions with comparable elevation ranges. Beta-diversity declined along the elevation gradient due to a decrease in gamma-diversity, which was steeper than the decrease in alpha-diversity. This pattern persisted after controlling for alpha- and gamma-diversity variation, and the results were robust when different resampling schemes and diversity metrics were used. We conclude that in temperate forests the pattern of decreasing beta-diversity with elevation does not exclusively depend on variation in species pool size, as has been hypothesized, but also on variation in community assembly mechanisms. The results were consistent across resampling schemes and diversity measures, thus supporting the use of vegetation plot databases for understanding...Comment: Accepted version 25 pages, 5 figures, 1 tabl

Technology and Firm Size Distribution:Evidence from Italian Manufacturing

This paper explores the relationship between firm size distribution and technology. Similarly to Crosato and Ganugi (2006), we focus on six industries from the Micro1 survey by the Italian Statistical National Office (ISTAT). Firm technology is analysed across selected industries by means of a non-parametric production analysis, the Free Disposal Hull approach (Deprins et al., 1984; Kerstens and Vanden Eeckaut, 1999). The existence of a link between technical efficiency and size on the one hand, and between scale elasticity and size on the other is investigated. Graphical analyses show the absence of a clear-cut relation in the first case, while an inverse relation is found in the second one. Building on this relation, we inquire whether the shape of the firm size-distribution is related to a particular pattern of returns to scale. This problem is studied through the Zipf Plot (Stanley et al., 1995) of the Pareto IV distribution, which is concave for firms up to a given threshold, and then becomes linear. Results show that firms in the concave part of the plot experience increasing returns to scale. On the contrary, firms in the linear part are mainly characterised by constant returns to scale.Italian manufacturing; Free Disposal Hull; Pareto distributions; Returns to scale;