Verbindingen tussen agrarische ondernemers en burgers. Verkennend onderzoek naar verschillende typen verbindingen

Agrarische ondernemers en burgers zijn in de loop der jaren van elkaar verwijderd geraakt. Veel burgers komen nog maar weinig op het platteland, kennen geen boeren meer en het voedsel dat ze kopen komt niet meer van de boer om de hoek. Deze ontwikkelingen kunnen ertoe leiden dat het maatschappelijk draagvlak voor de land- en tuinbouw afneemt. Tegelijkertijd is er ook een andere trend waarneembaar; een trend waarin steeds meer ondernemers burgers bij hun bedrijf betrekken, ze uitnodigen op het bedrijf of producten en diensten aanbieden die de burger naar het bedrijf trekken. Ook veel burgers zijn actief op zoek naar een nieuwe relatie met de beheerder van het platteland en de producent van zijn voedsel. Daardoor ontstaan (nieuwe) verbindingen tussen boeren en burgers. Hierbij is niet alleen sprake van een economische relatie maar ook van een proces van opgaan in de maatschappij, van vermaatschappelijken. Onderwerp van dit onderzoek zijn de (nieuwe) verbindingen tussen agrarisch ondernemer en burger

Taal en beelden verbinden in Agropark Flevoland

Het project Agropark Flevoland bouwt voort op de cradle-to-cradlegedachte. Het streven is regionale kringlopen te sluiten en de economische duurzaamheid te versterken. Cruciaal daarbij is hoe zo’n globale ambitie zich verbindt met de dynamiek in bestaande netwerken van ondernemers, overheden en burgers. In dit project hebben onderzoekers een rol hebben gespeeld in het maken van deze verbinding

High precision frequency measurement of the 423 nm Ca I line

We have performed an accurate frequency calibration of the 4s2 1

Kolmogorov-Sinai entropy from recurrence times

Observing how long a dynamical system takes to return to some state is one of the most simple ways to model and quantify its dynamics from data series. This work proposes two formulas to estimate the KS entropy and a lower bound of it, a sort of Shannon's entropy per unit of time, from the recurrence times of chaotic systems. One formula provides the KS entropy and is more theoretically oriented since one has to measure also the low probable very long returns. The other provides a lower bound for the KS entropy and is more experimentally oriented since one has to measure only the high probable short returns. These formulas are a consequence of the fact that the series of returns do contain the same information of the trajectory that generated it. That suggests that recurrence times might be valuable when making models of complex systems

Matrix Models and D-branes in Twistor String Theory

We construct two matrix models from twistor string theory: one by dimensional reduction onto a rational curve and another one by introducing noncommutative coordinates on the fibres of the supertwistor space P^(3|4)->CP^1. We comment on the interpretation of our matrix models in terms of topological D-branes and relate them to a recently proposed string field theory. By extending one of the models, we can carry over all the ingredients of the super ADHM construction to a D-brane configuration in the supertwistor space P^(3|4). Eventually, we present the analogue picture for the (super) Nahm construction.Comment: 1+37 pages, reference added, JHEP style, published versio

Improved Laboratory Values of the H-2 Lyman and Werner Lines for Constraining Time Variation of the Proton-to-Electron Mass Ratio

Two distinct high-accuracy laboratory spectroscopic investigations of the H-2 molecule are reported. Anchor lines in the EF1 Sigma(+)(g)-X-1 Sigma(+)(g) system are calibrated by two-photon deep-UV Doppler-free spectroscopy, while independent Fourier-transform spectroscopic measurements are performed that yield accurate spacings in the B-1 Sigma(+)(u)-EF1 Sigma(+)(g) and I-1 Pi(g)-C-1 Pi(u) systems. From combination differences accurate transition wavelengths for the B-X Lyman and the C-X Werner lines can be determined with accuracies better than similar to 5x10(-9), representing a major improvement over existing values. This metrology provides a practically exact database to extract a possible variation of the proton-to-electron mass ratio based on H-2 lines in high-redshift objects. Moreover, it forms a rationale for equipping a future class of telescopes, carrying 30-40 m dishes, with novel spectrometers of higher resolving powers

Bailing Out the Milky Way: Variation in the Properties of Massive Dwarfs Among Galaxy-Sized Systems

Recent kinematical constraints on the internal densities of the Milky Way's dwarf satellites have revealed a discrepancy with the subhalo populations of simulated Galaxy-scale halos in the standard CDM model of hierarchical structure formation. This has been dubbed the "too big to fail" problem, with reference to the improbability of large and invisible companions existing in the Galactic environment. In this paper, we argue that both the Milky Way observations and simulated subhalos are consistent with the predictions of the standard model for structure formation. Specifically, we show that there is significant variation in the properties of subhalos among distinct host halos of fixed mass and suggest that this can reasonably account for the deficit of dense satellites in the Milky Way. We exploit well-tested analytic techniques to predict the properties in a large sample of distinct host halos with a variety of masses spanning the range expected of the Galactic halo. The analytic model produces subhalo populations consistent with both Via Lactea II and Aquarius, and our results suggest that natural variation in subhalo properties suffices to explain the discrepancy between Milky Way satellite kinematics and these numerical simulations. At least ~10% of Milky Way-sized halos host subhalo populations for which there is no "too big to fail" problem, even when the host halo mass is as large as M_host = 10^12.2 h^-1 M_sun. Follow-up studies consisting of high-resolution simulations of a large number of Milky Way-sized hosts are necessary to confirm our predictions. In the absence of such efforts, the "too big to fail" problem does not appear to be a significant challenge to the standard model of hierarchical formation. [abridged]Comment: 12 pages, 3 figures; accepted by JCAP. Replaced with published versio

Exponential distribution of long heart beat intervals during atrial fibrillation and their relevance for white noise behaviour in power spectrum

The statistical properties of heart beat intervals of 130 long-term surface electrocardiogram recordings during atrial fibrillation (AF) are investigated. We find that the distribution of interbeat intervals exhibits a characteristic exponential tail, which is absent during sinus rhythm, as tested in a corresponding control study with 72 healthy persons. The rate of the exponential decay lies in the range 3-12 Hz and shows diurnal variations. It equals, up to statistical uncertainties, the level of the previously uncovered white noise part in the power spectrum, which is also characteristic for AF. The overall statistical features can be described by decomposing the intervals into two statistically independent times, where the first one is associated with a correlated process with 1/f noise characteristics, while the second one belongs to an uncorrelated process and is responsible for the exponential tail. It is suggested to use the rate of the exponential decay as a further parameter for a better classification of AF and for the medical diagnosis. The relevance of the findings with respect to a general understanding of AF is pointed out