Qualitative and quantitative investigation of the propagation noise in various reactor systems

The space-dependent neutron noise, induced by propagating perturbations (propagation noise for short) is investigated in a one-dimensional homogeneous model of various reactor systems. By using two-group theory, the noise in both the fast and the thermal group is calculated. The purpose is to investigate the dependence of the properties of the space-dependent fast and thermal propagation noise on the static neutron spectrum as well as on the presence of the fluctuations of several cross sections. The motivation for this study arose in connection with recent work on neutron noise in molten salt reactors (MSR) with propagating fuel of various compositions. Some new features of the induced noise were observed, but it was not clear whether these were due to the propagating perturbation alone, or to the propagation of the fuel and hence that of the delayed neutron precursors. The present study serves to clarify the significance of the spectral properties of the different cores through calculating the propagation noise in four different reactor systems, as well as considering the influence of the perturbation of the various cross sections. By comparing the results with those obtained in MSR, the effect of the moving fuel on the propagation noise is clarified. It is shown that in fast systems the noise in the fast group is much larger than in the thermal group and hence can gain diagnostic importance. It is also shown that the coexistence of several cross section fluctuations leads to qualitatively and quantitatively new characteristics of the noise, hence it is important to model the effect of e.g. temperature fluctuations of the coolant in a proper way. (C) 2013 Elsevier Ltd. All rights reserved

Attitudes, norms and barriers of livestock trading : how does its use affect quality, competitiveness and added value in the beef industry?

I svensk nötköttsproduktion råder stor diversitet i avelsmaterial och produktionsformer. Diversitet gör att det finns en rad olika kvalitetsegenskaper och mervärden för livdjur i ett förmedlingsstadie. Majoriteten av förmedlingen sker genom de två största slakterierna i Sverige, HK Scan och KLS Ugglarps. Slakterierna har i regel åtaganderättförbehåll på de djur de förmedlar, vilket påverkar lantbrukarnas förhandlingsutrymme. I länder som Storbritannien, Kanada och USA har, man istället för förmedling genom slakterier, fysiska auktioner där slutproducenterna får buda mot varandra om högsta pris. I takt med digitaliseringens frammarsch har användandet av digitala auktionsplattformar ökat i en rad olika branscher. Exempel på digitala auktionsplattformar i nöttköttsbranschen är Svensk köttrasprövnings tjurauktioner och Boskapstorget, som riktar in sig på förmedling av avelsdjur och livdjur. Intresse för digitala auktionsplattformar, så som Boskapstorget, finns bland livdjursproducenter. Dock har den faktiska användningen genom sajten varit svag. Undersökningens syfte var att, med teorin om planerat beteende, identifiera vilka attityder, normer och hinder som påverkar användningen av förmedlingsavtal och digitala auktionsplattformar. Studien har också att berört hur alternativen påverkar arbetet med kvalité, konkurrenskraft och främjandet av mervärden i nötköttsbranschen. Detta för att det finns en uppfattning bland producenter att det finns möjlighet till förbättring inom dessa tre områden. Studien innefattade 13 st. telefonintervjuer med ett standardiserat frågeformulär. Studien har konstaterat att återleveranskrav och ett litet förhandlingsutrymme är de två största hindren för producenter att använda förmedlingsavtal. Dock gör bristen på alternativ, den uppleva ekonomiska tryggheten och tryggheten i att alltid kunna sälja eller köpa djur att de allra flesta producenter ändå väljer förmedlingsavtal. Om förmedlingsavtalen ska stimulera kvalité, konkurrenskraft och mervärden behöver avtalen utvecklas så att mervärden och kvalité premierar uppfödaren ekonomiskt. Vilket i förlängningen kommer underlätta producenternas konkurrentsituation. Intentionen med digital livdjursförmedling är att den fria prissättningen kommer underlätta förmedling av mervärden och stimulera producenter att producera djur av god kvalité. Det kommer i sin tur förbättra konkurrenssituationen för de producenter som satsar på mervärden och kvalité. Avgörande faktorer för en utbred användning är säkerställandet av en säker betallösning och smittuppföljning. Skulle varumärket skadas i ett tidigt stadium skulle det bli förödande för fortsatt användning och utveckling. Dock går det inte att utesluta att det kan finnas andra oanade och oönskade konsekvenser av digitala auktionsplattformar för livdjur. Konsekvenser som upptäcks vid en omfattande användning.Swedish beef production contains a big diversity when it comes to breeding materials and types of production systems. Due to the diversity there is different quality and added value in the livestock trading. The majority of the livestock trading appears through the two biggest stakeholders of Sweden (HK Scan and KLS-Ugglarps). The stakeholders have the right to slaughter the cattle that they have sold to the farmer though their livestock trading service. In countries like Great Britten, Canada and USA is the norm to buy or sell the livestock though livestock auctioneers. Where the byers compete against each other about having the highest offer. In times of the digital evolution has the use of digital auctions increased in different industries. Examples of digital auction platforms in the beef industry is Svensk köttrasprövning and Boskapstorget. There is interest of using digital auction platforms among the beef producers rather than using the traditional livestock trading by the stakeholders. Despite the interest, the actual use of the digital auction platforms has been low. The purpose of the study was to identify which attitudes, norms and barriers which effects the use of traditional livestock trading and the possible use of a digital auction platform. The study has also identified how the alternatives affects the work whit quality, competitiveness and added value in the beef industry. The study included thirteen respondents who participated through telephone interview. The conclusions of the study were that the reservation of the slaughter and the small space of negotiation are the two biggest barriers of using traditional livestock trading. However, the lack of alternative ways of trading livestock, the sense of economical trustiness and ability to always trade animals makes the livestock trading through the stakeholders attractive. If the livestock trading through the stakeholders should simulate quality, competitiveness and added value the system needs to develop so the added value and quality makes a financial difference for the calf producer. The financial difference will stimulate the competitiveness of producers. The intention of digital auction platforms is that the market-based pricing of cattle will stimulate added value and stimulate producers to breed cattle of good quality. It will improve the competitiveness for the producers that invests in added value and quality. The main factor of using is the ensuring of a safe financial transaction and infection control. If the trademark harms in an early stage, it will be devastating for a continues use and develop. However, the study cannot exclude the fact that it can be other unwanted consequences with the use of digital auction platforms for trading livestock

Why are CSPs Based on Partition Schemes Computationally Hard?

Many computational problems arising in, for instance, artificial intelligence can be realized as infinite-domain constraint satisfaction problems (CSPs) based on partition schemes: a set of pairwise disjoint binary relations (containing the equality relation) whose union spans the underlying domain and which is closed under converse. We first consider partition schemes that contain a strict partial order and where the constraint language contains all unions of the basic relations; such CSPs are frequently occurring in e.g. temporal and spatial reasoning. We identify three properties of such orders which, when combined, are sufficient to establish NP-hardness of the CSP. This result explains, in a uniform way, many existing hardness results from the literature. More importantly, this result enables us to prove that CSPs of this kind are not solvable in subexponential time unless the exponential-time hypothesis (ETH) fails. We continue by studying constraint languages based on partition schemes but where relations are built using disjunctions instead of unions; such CSPs appear naturally when analysing first-order definable constraint languages. We prove that such CSPs are NP-hard even in very restricted settings and that they are not solvable in subexponential time under the randomised ETH. In certain cases, we can additionally show that they cannot be solved in O(c^n) time for any c >= 0

Autonomous Drug Design with Reinforcement Learning

The drug design process is currently one of manual trial and error, where potential drug candidates are proposed by chemists, synthesized in laboratories, and then tested and analyzed for properties and efficacy. This process, also called the Design- Make-Test-Analyze (DMTA) cycle, is repeated until a satisfying drug candidate is reached. Statistical models to sample the chemical space and generate potential molecules, combined with automated laboratories and machine learning allows for the automatization of the DMTA-cycle. However, there is still a need for improvement and this is where our project comes in. One way to improve the automatization of the DMTA-cycle is to reduce the number of cycles needed, and our aim was to achieve this by improving the selection of compounds. To do this, we developed two deep reinforcement learning algorithms, Deep-Q Network (DQN) and Double Deep-Q Network (DDQN), and compared these to two baseline selection algorithms. This approach was chosen as it translates well into the drug development field. Reinforcement learning in drug discovery works by exploring the proposed molecules to find potential candidates and selecting the most promising ones based on molecular similarity to some predetermined properties. Ultimately, the project was unsuccessful. The baseline selection algorithms using random and greedy selection approaches proved more efficient and accurate than the two algorithms we developed. The involvement of reinforcement learning agents when selecting compounds seemed to cloud the generative model’s understanding of what constitutes a good molecule, and thereby reduced the quality of proposed molecules for both the implemented selection algorithms. However, we found that the DQN algorithm shows some signs of promise and can, with some fine-tuning, potentially be brought up to par with the baseline selection algorithms, and perhaps even surpass them

CSPs with Few Alien Constraints

The constraint satisfaction problem asks to decide if a set of constraints over a relational structure is satisfiable (CSP()). We consider CSP( ∪ ℬ) where is a structure and ℬ is an alien structure, and analyse its (parameterized) complexity when at most k alien constraints are allowed. We establish connections and obtain transferable complexity results to several well-studied problems that previously escaped classification attempts. Our novel approach, utilizing logical and algebraic methods, yields an FPT versus pNP dichotomy for arbitrary finite structures and sharper dichotomies for Boolean structures and first-order reducts of (ℕ, =) (equality CSPs), together with many partial results for general ω-categorical structures

Different reprogramming propensities in plants and mammals: Are small variations in the core network wirings responsible?

Although the plant and animal kingdoms were separated more than 1,6 billion years ago, multicellular development is for both guided by similar transcriptional, epigenetic and posttranscriptional machinery. One may ask to what extent there are similarities and differences in the gene regulation circuits and their dynamics when it comes to important processes like stem cell regulation. The key players in mouse embryonic stem cells governing pluripotency versus differentiation are Oct4, Sox2 and Nanog. Correspondingly, the WUSCHEL and CLAVATA3 genes represent a core in the Shoot Apical Meristem regulation for plants. In addition, both systems have designated genes that turn on differentiation. There is very little molecular homology between mammals and plants for these core regulators. Here, we focus on functional homologies by performing a comparison between the circuitry connecting these players in plants and animals and find striking similarities, suggesting that comparable regulatory logics have been evolved for stem cell regulation in both kingdoms. From in silico simulations we find similar differentiation dynamics. Further when in the differentiated state, the cells are capable of regaining the stem cell state. We find that the propensity for this is higher for plants as compared to mammalians. Our investigation suggests that, despite similarity in core regulatory networks, the dynamics of these can contribute to plant cells being more plastic than mammalian cells, i.e. capable to reorganize from single differentiated cells to whole plants-reprogramming. The presence of an incoherent feed-forward loop in the mammalian core circuitry could be the origin of the different reprogramming behaviour

From eruption to construction - Part B: Investigating the feasibility of volcanic material as partial replacement for cement in concrete

This study investigates to what extent supplementary cementitious materials, (SCMs) of volcanic material (VM) together with limestone (LS) can replace ordinary Portland cement, (OPC) in concrete through an experimental study. The study is done in collaboration with a partner group named Part A. They are conducting a similar study in which part SCM is replaced only with VM. The project is thus divided into two parts, with this study being part B. Nine mortar mixtures were tested for compressive strength, with an accompanying X-ray diffraction (XRD) analysis of pastes, to assess chemical properties over time. Out of the nine mixtures, one contains 100% OPC and is referred to as the reference mix (REF). Additionally, there are four mixtures with varying proportions of VM and LS, and four filler mixtures with corresponding amounts of filler to the VM-LS mixtures. Furthermore, a thorough explanation of key materials and concepts is done to provide enough information for sufficient understanding. A detailed description of methods is provided and specific information on each material used, such as Icelandic hyaloclastite from Grindavik and limestone from Cementa, Sweden. Compressive strength tests were performed to evaluate the strength properties of each mixture relative to a reference mix (REF). Through these results, the optimal ratio of VM and LS to OPC can be concluded. This study showed that the mixture substituted with 40% SCM composed of 30% VM and 10% LS provided the highest strength properties and was comparable to the reference mixture of 100 percent OPC. Therefore, this study concluded that hyaloclastite and limestone can replace 40% of OPC in concrete

Effects of Greenhouse Gases Like Carbon Dioxide Can Be Spotted Earlier in the Middle Atmosphere

Understanding and dealing with climate change requires us to look at the atmosphere as a whole, not just the lowest portion near the surface. Analyzing the effects of greenhouse gases on the middle atmosphere helps to identify and understand the effects of climate change early on.York's Knowledge Mobilization Unit provides services and funding for faculty, graduate students, and community organizations seeking to maximize the impact of academic research and expertise on public policy, social programming, and professional practice. It is supported by SSHRC and CIHR grants, and by the Office of the Vice-President Research & Innovation. [email protected] www.researchimpact.c

Measurements of differential cross sections of Z/gamma*+jets+X events in proton anti-proton collisions at sqrt{s}=1.96 TeV

We present cross section measurements for Z/gamma*+jets+X production, differential in the transverse momenta of the three leading jets. The data sample was collected with the D0 detector at the Fermilab Tevatron proton anti-proton collider at a center-of-mass energy of 1.96 TeV and corresponds to an integrated luminosity of 1 fb-1. Leading and next-to-leading order perturbative QCD predictions are compared with the measurements, and agreement is found within the theoretical and experimental uncertainties. We also make comparisons with the predictions of four event generators. Two parton-shower-based generators show significant shape and normalization differences with respect to the data. In contrast, two generators combining tree-level matrix elements with a parton shower give a reasonable description of the the shapes observed in data, but the predicted normalizations show significant differences with respect to the data, reflecting large scale uncertainties. For specific choices of scales, the normalizations for either generator can be made to agree with the measurements.Comment: Published in PLB. 11 pages, 3 figure

Analys av kringtidens inverkan på hemtjänsten i Östra Göinge kommun

Hemtjänsten i Sverige har problem med höga kostnader. Detta stämmer även överens med Östra Göinge kommuns hemtjänst där kostnaderna nästintill dubblerats på några år. En bidragande orsak är att alltför stor del av vårdpersonalens tid inte utförs hos brukarna, utan utgörs av så kallad kringtid. Syftet med rapporten är att kartlägga kringtiden i Östra Göinges hemtjänst och ge förslag för att reducera den, på ett hållbart sätt, för att ge mer tid hos brukaren och minska verksamhetens ekonomiska underskott. För att reducera kringtiden har tre potentiella förändringsområden valts ut: ruttoptimering, tillitsbaserad styrning och mobil dokumentation. Ruttoptimering handlar om att ta fram den mest optimala rutten genom en uppsättning noder med avseende på en vald parameter som exempelvis tid eller sträcka. Tillitsbaserad styrning ämnar att genom mindre detaljstyrning effektivisera och utveckla verksamheten. Onödig administration och andra tidstjuvar ska elimineras genom att det etableras tillit mellan aktörer i hierakikedjan. Det sista förändringsområdet handlar om att dokumentera händelser och uppgifter som avviker från genomförandeplanen direkt hos brukaren via en applikation. För att besvara frågeställningarna har två studier som grundar sig på kvalitativ metodik utförts. Den ena kartlägger kringtiden och förutsättningar i Östra Göinge och den andra analyserar de tre förändringsområdena. Kartläggningen av kringtiden och dess påverkan på ekonomin utfördes genom intervjuer med tjänstemän inom hemtjänsten och en enkäntundersökningen bland vårdpersonalen. För att förklara och förstå de tre förändringsområdena gjordes en litteraturgenomgång som kompletterades med intervjuer. I kartläggningen framkom det att kringtiden utgör en stor del av all tid, där de fem största posterna är planering, körtid, förberedelser, möten och dokumentation. Det kunde även konstateras att kringtiden påverkar ekonomin i stor utsträckning. Ruttoptimering, tillitsbaserad styrning och mobil dokumentation har alla potential att reducera kringtiden. Reduktionen från förändringsområdena är dock olika stor och med varierande osäkerhet