Effects of ground movements on realistic guide models for the European Spallation Source

We model the effect of ground movement, based on empirical experience, on the transport properties of long neutron guides by ray-tracing simulations. Our results reproduce the large losses found by an earlier study for a simple model, while for a more realistic engineering model of guide mounting, we find the losses to be significantly smaller than earlier predicted. A detailed study of the guide for the cold neutron spectrometer BIFROST at the European Spallation Source shows that the loss is 7.0(5) % for wavelengths of 2.3-4.0 {\AA}; the typical operational wavelength range of the instrument. This amount of loss does not call for mitigation by overillumination as suggested in the previous work. Our work serves to quantify the robustness of the transport properties of long neutron guides, in construction or planning at neutron facilities worldwide.Comment: 8 pages, 12 figure

Petroleum production in symbiosis with fisheries? The Norwegian experience

Fisheries and offshore Oil and Gas (O&G) industries have a long history of co-existence. Both industries leave an impact on the marine environment, and are subject to regulations in order to ensure sustainable use of resources. Offshore O&G exploration, drilling and production activities may impact fisheries through seismic activities, discharge of hazardous waste and presence of physical structures. Historically, cuttings from drilling sub-surface wells have been deposited directly from the platform to the seabed. However, environmental laws and regulations for the Norwegian offshore sector prohibit such practice when the oil on cutting exceeds 1% by weight. Re-injection of cuttings as a slurry into subsurface formations is still practiced. Due to migration, leaks, re-entering of slurry onto the seabed, and collapsing formations this disposal method is on a decline. Transport of oily cuttings to shore for final treatment is the preferred Norwegian practice. However, cutting treatment on platforms is also continuously evaluated. For logistics and cost reasons, as well as health, safety and environmental (HSE) and working environment reasons, emphasis is put on offshore waste minimization, reuse and recycle.Les pêches et les industries Pétrolières et Gazières (P&G) offshore ont une longue histoire de coexistence. Les deux industries laissent un impact sur le milieu marin et sont soumises à des règlements afin de garantir une utilisation durable des ressources. Les activités d’exploration offshore, forage et production de P&G peuvent affecter les pêches à travers des activités sismiques, le déversement de déchets dangereux et la présence de structures physiques. Historiquement, les déblais provenant de puits de forage sous la surface ont été déposés directement à partir de la plateforme au fond marin. Cependant, les lois et règlements environnementaux pour le secteur offshore norvégien interdisent une telle pratique lorsque l’huile de la coupe dépasse 1% en poids. La réinjection de déblais sous forme de boue dans des formations souterraines est encore pratiquée. À cause de la migration, les fuites, la boue rentrant sur le fond marin et l’effondrement des formations, cette méthode d’élimination est sur le déclin. Le transport des déblais huileux à terre pour le traitement final c’est la pratique que privilégient les norvégiens. Toutefois, le traitement des déblais sur les plateformes est également évalué en permanence. Pour des raisons de logistique et de coût, ainsi que pour des raisons de santé, de sécurité et d’environnement (HSE) et de milieu de travail, l’accent est mis sur la réduction des déchets en mer, la réutilisation et le recyclage

Urban meadows – maintenance, construction and difficulties : a literature study of urban green spaces

Det här arbetet undersöker vilken problematik man kan stöta på vid anläggning och skötsel av urbana ängar. Arbetet undersöker och diskuterar även olika förslag av lösningar på dessa problem. Genom en litteraturstudie undersöks först gräsytor och olika sorters ängar, såsom traditionella och måleriska ängar. Vidare undersöks olika metoder för anläggning och skötsel vid varje ängsyta. Kring anläggningen diskuteras erfarenheten som krävs, detta i anledning av att varje ängsyta kräver en unik anläggning beroende på miljöförhållanden. Det redovisas olika ängstyper och var dessa bör anläggas samt vilka fördelar och nackdelar de olika ängarna kan ha. Det undersöks vad en målerisk äng kan ha för fördelar framför en perenn äng i urbana sammanhang. Diskussionen kring skötseln problematiserar mycket runt slåttern då det är en skötselaspekt som de flesta ängar har. Kommuner, bostadsbolag och entreprenörer har höga deponeringsavgifter då de ofta inte har egna komposter. I samband med detta diskuteras olika lösningar för slåttern, såsom biogas eller kompostering.This paper examines different problems with constructing and maintaining urban meadows, it also examines and discusses different propositions for solutions of these problems. Through a literature study, grass surfaces are first examined and thereafter different kinds of meadows such as traditional meadows and ephemeral meadows. With every type of meadow different methods of construction and maintainance are investigated aswell. On the subject of construction, the need of experience is discussed since every construction is unique due to the difference of every site’s environment. Different types of meadows are shown, with their pros and cons including most logical area for construction. It explores the pros an ephemeral meadow can have in comparison to a perennial urban meadow. In the argumentation about maintenance, it is problematized a lot around the subject of mowing, since it is an aspect most meadows have to deal with, the municipality, housing companies and entrepreneurs often have high costs associated with the mowing due to the lack of being able to compost. Adjacent to this, different solutions for the mowing are reviewed, such as turning it into biogas or composting

Microbiota composition of simultaneously colonized mice housed under either a gnotobiotic isolator or individually ventilated cage regime

Germ-free rodents colonized with microbiotas of interest are used for host-microbiota investigations and for testing microbiota-targeted therapeutic candidates. Traditionally, isolators are used for housing such gnotobiotic rodents due to optimal protection from the environment, but research groups focused on the microbiome are increasingly combining or substituting isolator housing with individually ventilated cage (IVC) systems. We compared the effect of housing systems on the gut microbiota composition of germ-free mice colonized with a complex microbiota and housed in either multiple IVC cages in an IVC facility or in multiple open-top cages in an isolator during three generations and five months. No increase in bacterial diversity as assessed by 16S rRNA gene sequencing was observed in the IVC cages, despite not applying completely aseptic cage changes. The donor bacterial community was equally represented in both housing systems. Time-dependent clustering between generations was observed in both systems, but was strongest in the IVC cages. Different relative abundance of a Rikenellaceae genus contributed to separate clustering of the isolator and IVC communities. Our data suggest that complex microbiotas are protected in IVC systems, but challenges related to temporal dynamics should be addressed

METAMOC: Modular Execution Time Analysis using Model Checking

Safe and tight worst-case execution times (WCETs) are important when scheduling hard real-time systems. This paper presents METAMOC, a path-based, modular method, based on model checking and static analysis, that determines safe and tight WCETs for programs running on platforms fea-turing caching and pipelining. The method works by constructing a UPPAAL model of the program being analysed and annotating the model with information from an inter-procedural value analysis. The program model is then combined with a model of the hardware platform, and model checked for the WCET. Through support for the platforms ARM7, ARM9 and ATMEL AVR 8-bit the modularity and retargetability of the method is demonstrated, as only the pipeline needs to be remodelled. Mod-elling the hardware is performed in a state-of-the-art graphical modeling environment. Experiments on the Mälardalen WCET benchmark programs show that taking caching into account yields much tighter WCETs, and that METAMOC is a fast and versatile approach for WCET analysis. 1

Coloring Graphs with Forbidden Minors

Hadwiger's conjecture from 1943 states that for every integer $t\ge1$, every graph either can be $t$-colored or has a subgraph that can be contracted to the complete graph on $t+1$ vertices. As pointed out by Paul Seymour in his recent survey on Hadwiger's conjecture, proving that graphs with no $K_7$ minor are $6$-colorable is the first case of Hadwiger's conjecture that is still open. It is not known yet whether graphs with no $K_7$ minor are $7$-colorable. Using a Kempe-chain argument along with the fact that an induced path on three vertices is dominating in a graph with independence number two, we first give a very short and computer-free proof of a recent result of Albar and Gon\c{c}alves and generalize it to the next step by showing that every graph with no $K_t$ minor is $(2t-6)$-colorable, where $t\in\{7,8,9\}$. We then prove that graphs with no $K_8^-$ minor are $9$-colorable and graphs with no $K_8^=$ minor are $8$-colorable. Finally we prove that if Mader's bound for the extremal function for $K_p$ minors is true, then every graph with no $K_p$ minor is $(2t-6)$-colorable for all $p\ge5$. This implies our first result. We believe that the Kempe-chain method we have developed in this paper is of independent interest