The Puzzle of Environmental Politics

In this report we study estimation of time-delays in linear dynamical systems with additive noise. Estimating time-delays is a common engineering problem, e.g. in automatic control, system identification and signal processing. The purpose with this work is to test and evaluate a certain class of methods for time-delay estimation, especially with automatic control applications in mind. Particularly interesting it is to determine the best method. Is one method best in all situations or should different methods be used for different situations? The tested class of methods consists essentially of thresholding the cross correlation between the output and input signals. This is a very common method for time-delay estimation. The methods are tested and evaluated experimentally with the aid of simulations and plots of RMS error, bias and confidence intervals. The results are: The methods often miss to detect because the threshold is too high. The threshold has nevertheless been selected to give the best result. All methods over-estimate the time-delay. Nearly the whole RMS error is due to the bias. None of the tested methods is always best. Which method is best depends on the system and what is done when missing detections. Some form of averaging of the cross correlation, e.g. integration to step response or CUSUM, is advantageous. Fast systems are easiest. White noise input signal is easiest and steps is hardest. The RMS-errors are high in average (approximately greater than 6 sampling intervals). The error is lower for fast system or for high SNR

Geofysisch onderzoek binnen het \u27Nieuwerck\u27 van de kathedraal van Antwerpen (Antwerpen, provincie Antwerpen)

Van 11 tot en met 15 februari 2013 werd door ADEDE bvba in de tuin van het Nieuwerck te Antwerpen een non-destructieve geofysische prospectie uitgevoerd. Deze tuin bevindt zich ten oosten van de Onze-Lieve-Vrouwekathedraal, tussen de Groenplaats, de Melkmarkt en de Lijnwaadmarkt. De totale toegankelijke oppervlakte van het onderzoeksterrein (i. e. vrij van vegetatie) bedroeg 415m². Ondanks een verstoorde (puin)bodem en het versnipperde onderzoeksgebied (bomen, struiken en een vijver) was de inzet van geofysische detectiemethoden zinvol. De grondradar met 200MHz antenne leverde daarbij wel betere resultaten op dan de conductiviteits- en de magnetische susceptibiliteitmetingen met behulp van de EM31-MK2. Binnen het dossier van het Nieuwerck hebben de gekozen geofysische methodes aangetoond dat er een groot aantal structuren in de bodem kunnen geregistreerd worden, ook al is er een hoge graad van verstoring (door heterogene grond met puin). Na uitvoering van de detectie en terugkoppeling met bestaande boorgegevens konden met zekerheid drie en waarschijnlijk twaalf structuren herkend worden, alsook werd er een beeld gevormd van hoe de opbouw van de opvulling van het Nieuwerck in elkaar zit. Door de dikte van de opvulling konden dieperliggende structuren niet vastgesteld worden

Functional connectivity network between terrestrial and aquatic habitats by a generalist waterbird, and implications for biovectoring

Birds are vectors of dispersal of propagules of plants and other organisms including pathogens, as well as nutrients and contaminants. Thus, through their movements they create functional connectivity between habitat patches. Most studies on connectivity provided by animals to date have focused on movements within similar habitat types. However, some waterbirds regularly switch between terrestrial, coastal and freshwater habitats throughout their daily routines. Lesser black-backed gulls that overwinter in Andalusia use different habitat types for roosting and foraging. In order to reveal their potential role in biovectoring among habitats, we created an inter-habitat connectivity network based on GPS tracking data. We applied connectivity measures by considering frequently visited sites as nodes, and flights as links, to determine the strength of connections in the network between habitats, and identify functional units where connections are more likely to happen. We acquired data for 42 tagged individuals (from five breeding colonies), and identified 5676 direct flights that connected 37 nodes. These 37 sites were classified into seven habitat types: reservoirs, natural lakes, ports, coastal marshes, fish ponds, rubbish dumps and ricefields. The Donana ricefields acted as the central node in the network based on centrality measures. Furthermore, during the first half of winter when rice was harvested, ricefields were the most important habitat type in terms of total time spent. Overall, 90% of all direct flights between nodes were between rubbish dumps (for foraging) and roosts in other habitats, thereby connecting terrestrial and various wetland habitats. The strength of connections decreased between nodes as the distance between them increased, and was concentrated within ten independent spatial and functional units, especially between December and February. The pivotal role for ricefields and rubbish dumps in the network, and their high connectivity with aquatic habitats in general, have important implications for biovectoring into their surroundings. (C) 2019 The Authors. Published by Elsevier B.V

Anisotropic vortex pinning in superconductors with a square array of rectangular submicron holes

We investigate vortex pinning in thin superconducting films with a square array of rectangular submicron holes ("antidots"). Two types of antidots are considered: antidots fully perforating the superconducting film, and "blind antidots", holes that perforate the film only up to a certain depth. In both systems, we observe a distinct anisotropy in the pinning properties, reflected in the critical current Ic, depending on the direction of the applied electrical current: parallel to the long side of the antidots or perpendicular to it. Although the mechanism responsible for the effect is very different in the two systems, they both show a higher critical current and a sharper IV-transition when the current is applied along the long side of the rectangular antidots

Vortex Structure Around a Magnetic Dot in Planar Superconductors

The problem of the giant vortex state around a magnetic dot which is embedded in a superconducting film is investigated. The full non-linear, self-consistent Ginzburg-Landau equations are solved numerically in order to calculate the free energy, the order parameter of the host superconductor, the internal magnetic field due to the supercurrents, the corresponding current density, the magnetization probed in the vicinity of the dot, and the normal electron density as a function of the various parameters of the system. We find that, as we increase the magnetic moment of the dot, higher flux quanta vortex states become energetically more favorable, as they can better compete with the external magnetic field via the Meissner effect. In addition to that, they progressively become closer to each other in energy with direct experimental consequences, i.e. physical quantities like magnetization may fluctuate when measured, for example, as a function of a uniform external magnetic field.Comment: text 21 pages (REVTEX), 8 figures available upon reques

Hatano-Nelson model with a periodic potential

We study a generalisation of the Hatano-Nelson Hamiltonian in which a periodic modulation of the site energies is present in addition to the usual random distribution. The system can then become localized by disorder or develop a band gap, and the eigenspectrum shows a wide variety of topologies. We determine the phase diagram, and perform a finite size scaling analysis of the localization transition.Comment: 7 pages, 10 figure

Asymmetric Field Profile in Bose Glass Phase of Irradiated YBa2Cu3O7-d: Loss of Interlayer Coherence around 1/3 of Matching Field

Magneto-optical imaging in YBa2Cu3O7-d with tilted columnar defects (CD's) shows an asymmetric critical-state field profile. The observed hysteretic shift of the profile ridge (trough) from the center of the sample is explained by in-plane magnetization originated from vortex alignment along CD's. The extracted ratio of the in-plane to out-of-plane magnetization component has a maximum at 1/5 of matching field ($B_\Phi$) and disappears above $B_\Phi/3$, suggesting a reduction of interlayer coherence well bellow $B_\Phi$ in the Bose glass phase. Implications are discussed in comparison with the vortex liquid recoupling observed in irradiated Bi2Sr2CaCu2O8+y.Comment: Revtex, 4 pages, 5 figures, also see a movie at (http://www.ap6.t.u-tokyo.ac.jp/kitaka/Research/d-line/index_e.htm). This manuscript will appear in Phys. Rev. Let

Magnetic Pinning of Vortices in a Superconducting Film: The (anti)vortex-magnetic dipole interaction energy in the London approximation

The interaction between a superconducting vortex or antivortex in a superconducting film and a magnetic dipole with in- or out-of-plane magnetization is investigated within the London approximation. The dependence of the interaction energy on the dipole-vortex distance and the film thickness is studied and analytical results are obtained in limiting cases. We show how the short range interaction with the magnetic dipole makes the co-existence of vortices and antivortices possible. Different configurations with vortices and antivortices are investigated.Comment: 12 pages, 12 figures. Submitted to Phys. Rev.

Small heat shock proteins are induced during multiple sclerosis lesion development in white but not grey matter

INTRODUCTION: The important protective role of small heat-shock proteins (HSPs) in regulating cellular survival and migration, counteracting protein aggregation, preventing apoptosis, and regulating inflammation in the central nervous system is now well-recognized. Yet, their role in the neuroinflammatory disorder multiple sclerosis (MS) is largely undocumented. With the exception of alpha B-crystallin (HSPB5), little is known about the roles of small HSPs in disease. RESULTS: Here, we examined the expression of four small HSPs during lesion development in MS, focussing on their cellular distribution, and regional differences between white matter (WM) and grey matter (GM). It is well known that MS lesions in these areas differ markedly in their pathology, with substantially more intense blood-brain barrier damage, leukocyte infiltration and microglial activation typifying WM but not GM lesions. We analysed transcript levels and protein distribution profiles for HSPB1, HSPB6, HSPB8 and HSPB11 in MS lesions at different stages, comparing them with normal-appearing brain tissue from MS patients and non-neurological controls. During active stages of demyelination in WM, and especially the centre of chronic active MS lesions, we found significantly increased expression of HSPB1, HSPB6 and HSPB8, but not HSPB11. When induced, small HSPs were exclusively found in astrocytes but not in oligodendrocytes, microglia or neurons. Surprisingly, while the numbers of astrocytes displaying high expression of small HSPs were markedly increased in actively demyelinating lesions in WM, no such induction was observed in GM lesions. This difference was particularly obvious in leukocortical lesions covering both WM and GM areas. CONCLUSIONS: Since induction of small HSPs in astrocytes is apparently a secondary response to damage, their differential expression between WM and GM likely reflects differences in mediators that accompany demyelination in either WM or GM during MS. Our findings also suggest that during MS, cortical structures fail to benefit from the protective actions of small HSPs. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s40478-015-0267-2) contains supplementary material, which is available to authorized users