Sampling-based Approximations with Quantitative Performance for the Probabilistic Reach-Avoid Problem over General Markov Processes

This article deals with stochastic processes endowed with the Markov (memoryless) property and evolving over general (uncountable) state spaces. The models further depend on a non-deterministic quantity in the form of a control input, which can be selected to affect the probabilistic dynamics. We address the computation of maximal reach-avoid specifications, together with the synthesis of the corresponding optimal controllers. The reach-avoid specification deals with assessing the likelihood that any finite-horizon trajectory of the model enters a given goal set, while avoiding a given set of undesired states. This article newly provides an approximate computational scheme for the reach-avoid specification based on the Fitted Value Iteration algorithm, which hinges on random sample extractions, and gives a-priori computable formal probabilistic bounds on the error made by the approximation algorithm: as such, the output of the numerical scheme is quantitatively assessed and thus meaningful for safety-critical applications. Furthermore, we provide tighter probabilistic error bounds that are sample-based. The overall computational scheme is put in relationship with alternative approximation algorithms in the literature, and finally its performance is practically assessed over a benchmark case study

Differential sensitivity of locally naturalized Panicum species to HPPD- and ALS-inhibiting herbicides

Panicum schinzii (Transvaal millet), P. dichotomiflorum (Fall panicum) and P. capillare (Witchgrass) are alien panicoid grasses that have gradually spread and are now locally naturalized in corn fields in Belgium. One of the possible reasons for their expansion in corn fields might be a lower sensitivity to post-emergence herbicides acting against panicoid grasses, in particular those inhibiting 4-hydroxyphenyl pyruvate dioxygenase (HPPD) and acetolactate synthase (ALS). Dose-response pot experiments were conducted in the greenhouse to evaluate the effectiveness of five HP-PD-inhibiting herbicides (sulcotrione, mesotrione, isoxaflutole, topramezone, tembotrione) and two AILS-inhibiting herbicides (nicosulfuron, foramsulfuron) for controlling populations of P. schinzii, P. dichotomiflorum and P. capillare (all naturalized Belgian populations except for P. capillare). In another dose-response pot experiment, sensitivity of five local P. dichotomiflorum populations to HPPD-inhibitors and nicosulfuron was investigated. Finally, the influence of growth stage at time of herbicide application on efficacy of topramezone and nicosulfuron for Panicum control was evaluated. Large interspecific differences in sensitivity to HPPD-inhibiting herbicides were observed. Panicum schinzii was sensitive to tembotrione but moderately sensitive to topramezone and poorly sensitive to mesotrione and sulcotrione. However, P. dichotomiflorum was sensitive to mesotrione and topramezone but moderately sensitive to tembotrione. All Panicum species were sensitive to low doses of nicosulfuron and foramsulfuron. Naturalized P. dichotomiflorum populations exhibited differential herbicide sensitivity profiles. All species tested showed a progressive decrease in sensitivity to topramezone and nicosulfuron with seedling age. A satisfactory post-emergence control of Panicum species in the field will require appropriate choice of herbicide and dose, as well as a more timely application (i.e. before weeds reach the four leaves stage)

Vector-borne diseases in a warmer world: Will they stay or will they go?

Not available

Owner Occupied Housing in the CPI and its Impact on Monetary Policy during Housing Booms and Busts

The treatment of owner-occupied housing (OOH) is probably the most important unresolved issue in inflation measurement. How -- and whether -- it is included in the Consumer Price Index (CPI) affects inflation expectations, the measured level of real interest rates, and the behavior of governments, central banks and market participants. We show that none of the existing treatments of OOH are fit for purpose. Hence we propose a new simplified user cost method with better properties. Using a micro-level dataset, we then compare the empirical behavior of eight different treatments of OOH. Our preferred user cost approach pushes up the CPI during housing booms (by 2 percentage points or more). Our findings relate to the following important debates in macroeconomics: the behavior of the Phillips curve in the US during the global financial crisis, and the response of monetary policy to housing booms, secular stagnation, and globalization.Series: Department of Economics Working Paper Serie

Eine sinnvolle Ergänzung für die Ökokontrolle

Wie eine aktuelle Studie zeigt, reichen analytische und optische Verfahren nicht aus, um biologische und konventionelle Lebensmittel zweifelsfrei zu unterscheiden. Wohl aber können sie als Verifikationsinstrument dienen und so wichtige Hinweise für die Ökokontrolle liefern

Differential sensitivity of locally naturalized Panicum species to 4-hydroxyphenyl pyruvate dioxygenase and acetolactate synthase-inhibiting herbicides

One of the possible reasons for the expansion of the alien panicoid grasses Panicum schinzii (Transvaal millet), Panicum dichotomiflorum (Fall panicum) and Panicum capillare (Witchgrass) in maize fields in Belgium might be a lower sensitivity to post-emergence herbicides acting against panicoid grasses, in particular those inhibiting 4-hydroxyphenyl pyruvate dioxygenase (HPPD) and acetolactate synthase (ALS). Dose-response pot experiments were conducted in the greenhouse to evaluate the effectiveness of five HPPD-inhibiting herbicides (sulcotrione, mesotrione, isoxaflutole, topramezone, tembotrione) and two ALS-inhibiting herbicides (nicosulfuron, foramsulfuron) for controlling naturalized Belgian populations of P. schinzii, P. dichotomiflorum and P. capillare. In another dose-response pot experiment, sensitivity of five local P. dichotomiflorum populations to HPPD-inhibitors and nicosulfuron was investigated. Finally, the influence of growth stage at time of herbicide application on efficacy of topramezone and nicosulfuron for Panicum control was evaluated. Large interspecific differences in sensitivity to HPPD-inhibiting herbicides were observed. Panicum schinzii was sensitive (i.e., required a three-fold lower dose than maximum authorized field dose to achieve 90% reduction in biomass) to tembotrione but moderately sensitive (i.e. required maximum field dose) to topramezone and poorly sensitive (i.e. required three-fold higher dose than maximum field dose) to mesotrione and sulcotrione. However, P. dichotomiflorum, a species that morphologically closely resembles P. schinzii, was sensitive to mesotrione and topramezone but moderately sensitive to tembotrione. Panicum capillare was sensitive to sulcotrione and topramezone, moderately sensitive to tembotrione and poorly sensitive to mesotrione. All Panicum species were sensitive to low doses of nicosulfuron and foramsulfuron. Naturalized Panicum dichotomiflorum populations exhibited differential herbicide sensitivity profiles. All species tested showed a progressive decrease in sensitivity to topramezone and nicosulfuron with seedling age. A satisfactory post-emergence control of Panicum species in the field will require appropriate choice of herbicide and dose, as well as a more timely application (i.e. before weeds reach the four leaves stage).Keywords: Bioassay, herbicide sensitivity, leaf stage, nicosulfuron, panicoid grasses, triketoneDifferentielle Sensitivität von lokal naturalisierten Panicum-Arten gegenüber 4-Hydroxyphenylpyruvat-Dioxygenase und Acetolactat- Synthase hemmenden HerbizidenZusammenfassungEiner der möglichen Gründe für die rasche Ausbreitung der standortfremden Unkrauthirsen Panicum schinzii (Glattblättrige Hirse), Panicum dichotomiflorum (Gabelästige Rispenhirse) und Panicum capillare (Haarästige Rispenhirse) in Maisfeldern in Belgien könnte eine geringere Empfindlichkeit gegenüber Nachauflaufherbiziden sein, insbesondere 4-Hydroxyphenylpyruvat-Dioxygenase (HPPD)- und Acetolactat-Synthase (ALS)-Hemmer. Dosis-Wirkungs-Experimente wurden im Gefäßversuch im Gewächshaus durchgeführt, um die Wirksamkeit von fünf HPPD-inhibierenden Herbizidwirkstoffen (Sulcotrione, Mesotrione, Isoxaflutole, Topramezone, Tembotrione) und zwei ALS-inhibierenden Herbizidwirkstoffen (Nicosulfuron, Foramsulfuron) gegen naturalisierte belgische Populationen von P. schinzii, P. dichotomiflorum und P. capillare zu beurteilen. In einem weiteren Dosis-Wirkungs-Topf Experiment wurde die Empfindlichkeit von fünf lokal eingewanderten P. dichotomiflorum-Populationen gegenüber HPPD-Inhibitoren und Nicosulfuron untersucht. Schließlich wurde der Einfluss des Blattstadiums zum Zeitpunkt der Herbizid-Anwendung auf Wirksamkeit von Topramezone und Nicosulfuron für Panicum-Bekämpfung ausgewertet. Große interspezifische Unterschiede in der Empfindlichkeit gegenüber HPPD-inhibierenden Herbiziden wurden beobachtet. Panicum schinzii war empfindlich gegenüber Tembotrione aber mäßig empfindlich gegenüber Topramezone und leicht empfindlich gegenüber Mesotrione und Sulcotrione. Dagegen war P. dichotomiflorum empfindlich gegenüber Mesotrione und Topramezone aber mäßig empfindlich gegenüber Tembotrione. Panicum capillare war empfindlich gegenüber Sulcotrione und Topramezone, mäßig empfindlich gegenüber Tembotrione und leicht empfindlich gegenüber Mesotrione. Alle Panicum-Arten waren empfindlich gegenüber niedrigen Dosen von Nicosulfuron und Foramsulfuron. Eingebürgerte Panicum dichotomiflorum-Populationen zeigten differentielle Herbizid-Empfindlichkeitsprofile. Alle untersuchten Arten zeigten eine fortschreitende Abnahme der Empfindlichkeit gegenüber Topramezone und Nicosulfuron mit zunehmendem Blattstadium. Eine befriedigende Nachauflaufbekämpfung von Panicum-Arten in Maisäckern benötigt eine angemessene Wahl von Herbizid und Dosis sowie eine rechtzeitige Anwendung (das heißt vor dem Vierblattstadium).Stichwörter: Biotest, Blattstadium, Herbizidempfindlichkeit, Nicosulfuron, Triketone, Unkrauthirse

Lipidation effect on surface adsorption and associated fibrillation of the model protein insulin

Lipidation of proteins is used in the pharma- ceutical field to increase the therapeutic efficacy of proteins. In this study, we investigate the effect of a 14-carbon fatty acid modification on the adsorption behavior of human insulin to a hydrophobic solid surface and the subsequent fibrillation development under highly acidic conditions and elevated temperature by comparing to the fibrillation of human insulin. At these stressed conditions, the lipid modification accelerates the rate of fibrillation in bulk solution. With the use of several complementary surface-sensitive techniques, including quartz crystal microbalance with dissipation monitoring (QCM-D), atomic force microscopy (AFM), and neutron reflectivity (NR), we show that there are two levels of structurally different protein organization at a hydrophobic surface for both human insulin and the lipidated analogue: a dense protein layer formed within minutes on the surface and a diffuse outer layer of fibrillar structures which took hours to form. The two layers may only be weakly connected, and proteins from both layers are able to desorb from the surface. The lipid modification increases the protein surface coverage and the thickness of both layer organizations. Upon lipidation not only the fibrillation extent but also the morphology of the fibrillar structures changes from fibril clusters on the surface to a more homogeneous network of fibrils covering the entire hydrophobic surface