Systematic trends in beta-delayed particle emitting nuclei: The case of beta-p-alpha emission from 21Mg

We have observed beta+-delayed alpha and p-alpha emission from the proton-rich nucleus 21Mg produced at the ISOLDE facility at CERN. The assignments were cross-checked with a time distribution analysis. This is the third identified case of beta-p-alpha emission. We discuss the systematic of beta-delayed particle emission decays, show that our observed decays fit naturally into the existing pattern, and argue that the patterns are to a large extent caused by odd-even effects.Comment: 6 pages, 5 figure

Rational sequences for the conductance in quantum wires from affine Toda field theories

We analyse the expression for the conductance of a quantum wire which is decribed by an integrable quantum field theory. In the high temperature regime we derive a simple formula for the filling fraction. This expression involves only the inverse of a matrix which contains the information of the asymptotic phases of the scattering matrix and the solutions of the constant thermodynamic Bethe ansatz equations. Evaluating these expressions for minimal affine Toda field theory we recover several sequences of rational numbers, which are multiples of the famous Jain sequence for the filling fraction occurring in the context of the fractional quantum Hall effect. For instance we obtain $\nu= 4 m/(2m +1)$ for $A_{4m-1}$-minimal affine Toda field theory. The matrices involved have in general non-rational entries and are not part of previous classification schemes based on integral lattices.Comment: 9 pages Latex, version to appear in Journal of Physics

Customer Focused Price Optimisation

Tesco want to better understand how to set online prices for their general merchandise (i.e. not groceries or clothes) in the UK. Because customers can easily compare prices from different retailers we expect they will be very sensitive to price, so it is important to get it right. There are four aspects of the problem. • Forecasting: Estimating the customer demand as a function of the price chosen (especially hard for products with no sales history or infrequent sales). • Objective function: What exactly should Tesco aim to optimise? Sales volume? Profit? Profit margin? Conversion rates? • Optimisation: How to choose prices for many related products to optimise the chosen objective function. • Evalution: How to demonstrate that the chosen prices are optimal, especially to people without a mathematical background. Aggregate sales data was provided for about 400 products over about 2 years so that quantitive approaches could be tested. For some products competitors’ prices were also provided

Team i kommunal sektor

Tema for prosjektoppgaven er teamorganisering i kommunal sektor. I oppgaven har vi tatt for oss en teammodell i en kommunal enhet som både er demokratisk og kostnadseffektiv. Ved å se nærmere på hvilke suksesskriterier som ligger til grunn for teammodellen, har målet vært å finne ut om den kan overføres til andre kommunale enheter. Resultatene viser at teammodellen krever gode rammebetingelser for at den skal fungere optimalt. Særlig strukturell myndiggjøring er av stor betydning, det vil si en flatere organisering som gir medbestemmelse og ansvar til teamene. Av resultatene ser vi at teamlederen har en sentral rolle i teammodellen. Teamlederen er operativ, det vil si at han både har personalansvar og deltar i produksjonen på linje med øvrige teammedlemmer. Økt motivasjon, trivsel og læring er effekter av teammodellen, i tillegg til høy kvalitet på tjenesteproduksjonen. Sammen med relevant teori har informasjon fra ni dybdeintervju gitt svar på vår problemstilling. Prosjektoppgaven konkluderer med at teammodellen er veien å gå for flere kommunale enheter

Approximating k-Forest with Resource Augmentation: A Primal-Dual Approach

In this paper, we study the $k$-forest problem in the model of resource augmentation. In the $k$-forest problem, given an edge-weighted graph $G(V,E)$, a parameter $k$, and a set of $m$ demand pairs $\subseteq V \times V$, the objective is to construct a minimum-cost subgraph that connects at least $k$ demands. The problem is hard to approximate---the best-known approximation ratio is $O(\min\{\sqrt{n}, \sqrt{k}\})$. Furthermore, $k$-forest is as hard to approximate as the notoriously-hard densest $k$-subgraph problem. While the $k$-forest problem is hard to approximate in the worst-case, we show that with the use of resource augmentation, we can efficiently approximate it up to a constant factor. First, we restate the problem in terms of the number of demands that are {\em not} connected. In particular, the objective of the $k$-forest problem can be viewed as to remove at most $m-k$ demands and find a minimum-cost subgraph that connects the remaining demands. We use this perspective of the problem to explain the performance of our algorithm (in terms of the augmentation) in a more intuitive way. Specifically, we present a polynomial-time algorithm for the $k$-forest problem that, for every $\epsilon>0$, removes at most $m-k$ demands and has cost no more than $O(1/\epsilon^{2})$ times the cost of an optimal algorithm that removes at most $(1-\epsilon)(m-k)$ demands

Deltagardriven forskning – Växtodlingsgruppen, resultat och utvärdering av arbetet under 1998 till 2001

Då arbetet i växtodlingsgruppen påbörjades var förväntningarna på deltagardriven forskning att den sammanlagda erfarenheten hos lantbrukare, forskare och rådgivare skulle bidra till utförandet av relevanta gårdsförsök. Lantbrukarna önskade dessutom sträva efter att öka och vidarebefordra den kunskap som fanns i gruppen, samt att få etablerade forskare att undersöka områden som praktikerna upplever som viktiga och svåra. Redan i initialskedet slog växtodlingsgruppen fast att arbeta för att gemensamt identifiera problem och använda relevanta forskningsmetoder på gårdsnivå. Syftet var att genom olika odlingsåtgärder kunna förbättra förutsättningarna för ekologisk växtodling. Ett mål var att finna effektiva metoder för optimal växtnäringstillförsel i ekologisk produktion på lerjordar i Mälardalen. För närvarande saknas bra underlag för hur kväveleveransen varierar under säsongen framförallt till stråsäd. Detta påverkar i sin tur både skördeutfall, proteinhalt, miljöbelastning och ekonomi. Ett annat mål var att kunna reglera ogräsförekomsten, främst kvickrot och tistel, på ett effektivt sätt i växtföljden. Motivationen för lantbrukarna har under projektets gång varit att främja det ekologiska lantbruket som helhet. Detta har möjliggjorts genom erfarenhetsutbyte på gruppträffar kombinerat med gårdsbesök där lantbrukarnas intressen och frågeställningar har varit drivande. Växtodlingsgruppen har på så vis initialt bidragit till ett lokalt utvecklingsarbete och en uppbyggnad av ökat kunnande inom ekologiskt växtodling

Plasma cell-free DNA methylation marks for episodic memory impairment : a pilot twin study

Decline in episodic memory performance usually causes the first clinical symptoms of Alzheimer's disease. At present, Alzheimer's disease can only be diagnosed at a very late stage when neurodegeneration and cognitive impairment is already irreversible. New early disease markers are needed for earlier and more efficient Alzheimer's disease intervention. To identify early disease markers, we implemented a genome-wide bisulphite sequencing method for the analysis of plasma cell-free DNA methylation profiles and compared differences associated with episodic memory performance in Finnish twin pairs. A noticeable amount of cell-free DNA was present in plasma, however, the amounts as well as the genomic coverage of these fragments varied substantially between individuals. We found no significant markers associated with episodic memory performance in the twins' plasma cell-free DNA methylation profiles. Furthermore, our results indicate that due to the low genomic coverage of cell-free DNA fragments and the variety in these fragments between individuals, the implemented genome-wide bisulphite sequencing method is not optimal for comparing cell-free DNA methylation differences between large groups of individuals.Peer reviewe

(Total) Vector Domination for Graphs with Bounded Branchwidth

Given a graph $G=(V,E)$ of order $n$ and an $n$-dimensional non-negative vector $d=(d(1),d(2),\ldots,d(n))$, called demand vector, the vector domination (resp., total vector domination) is the problem of finding a minimum $S\subseteq V$ such that every vertex $v$ in $V\setminus S$ (resp., in $V$) has at least $d(v)$ neighbors in $S$. The (total) vector domination is a generalization of many dominating set type problems, e.g., the dominating set problem, the $k$-tuple dominating set problem (this $k$ is different from the solution size), and so on, and its approximability and inapproximability have been studied under this general framework. In this paper, we show that a (total) vector domination of graphs with bounded branchwidth can be solved in polynomial time. This implies that the problem is polynomially solvable also for graphs with bounded treewidth. Consequently, the (total) vector domination problem for a planar graph is subexponential fixed-parameter tractable with respectto $k$, where $k$ is the size of solution.Comment: 16 page

Development of an analogue optical link for the front-end read-out of the ATLAS electromagnetic calorimeter

We have developed an analogue optical data transmission system intended to meet the read-out requirements of the ATLAS liquid argon electromagnetic calorimeter. Eight-way demonstrators have been built and tested. The link uses arrays of VCSEL diodes as the optical emitters, coupled to a 70 m long fibre ribbon to simulate the distance between the detector and the control room. The receiver is based around a custom-designed PIN photodiode array. We describe here the final results of laboratory tests on a demonstrator, laying stress on the VCSEL-to-fibre coupling issues, and the overall performance of the full link. A 9-bit dynamic range is achieved, with a 5on-linearity