One n Remains to Settle the Tree Conjecture

In the famous network creation game of Fabrikant et al. a set of agents play a game to build a connected graph. The $n$ agents form the vertex set $V$ of the graph and each vertex $v\in V$ buys a set $E_v$ of edges inducing a graph $G=(V,\bigcup\limits_{v\in V} E_v)$. The private objective of each vertex is to minimize the sum of its building cost (the cost of the edges it buys) plus its connection cost (the total distance from itself to every other vertex). Given a cost of $\alpha$ for each individual edge, a long-standing conjecture, called the tree conjecture, states that if $\alpha > n$ then every Nash equilibrium graph in the game is a spanning tree. After a plethora of work, it is known that the conjecture holds for any $\alpha>3n-3$. In this paper we prove the tree conjecture holds for $\alpha>2n$. This reduces by half the open range for $\alpha$ with only $[n, 2n)$ remaining in order to settle the conjecture

Accelerated longitudinal designs: An overview of modelling, power, costs and handling missing data.

Longitudinal studies are often used to investigate age-related developmental change. Whereas a single cohort design takes a group of individuals at the same initial age and follows them over time, an accelerated longitudinal design takes multiple single cohorts, each one starting at a different age. The main advantage of an accelerated longitudinal design is its ability to span the age range of interest in a shorter period of time than would be possible with a single cohort longitudinal design. This paper considers design issues for accelerated longitudinal studies. A linear mixed effect model is considered to describe the responses over age with random effects for intercept and slope parameters. Random and fixed cohort effects are used to cope with the potential bias accelerated longitudinal designs have due to multiple cohorts. The impact of other factors such as costs and the impact of dropouts on the power of testing or the precision of estimating parameters are examined. As duration-related costs increase relative to recruitment costs the best designs shift towards shorter duration and eventually cross-sectional design being best. For designs with the same duration but differing interval between measurements, we found there was a cutoff point for measurement costs relative to recruitment costs relating to frequency of measurements. Under our model of 30% dropout there was a maximum power loss of 7%.This work was supported by the Medical Research Council (G0800860

Animals and Medicine

Animals and Medicine: The Contribution of Animal Experiments to the Control of Disease offers a detailed, scholarly historical review of the critical role animal experiments have played in advancing medical knowledge. Laboratory animals have been essential to this progress, and the knowledge gained has saved countless lives—both human and animal. Unfortunately, those opposed to using animals in research have often employed doctored evidence to suggest that the practice has impeded medical progress. This volume presents the articles Jack Botting wrote for the Research Defence Society News from 1991 to 1996, papers which provided scientists with the information needed to rebut such claims. Collected, they can now reach a wider readership interested in understanding the part of animal experiments in the history of medicine—from the discovery of key vaccines to the advancement of research on a range of diseases, among them hypertension, kidney failure and cancer. This book is essential reading for anyone curious about the role of animal experimentation in the history of science from the nineteenth century to the present

Probing a spin transfer controlled magnetic nanowire with a single nitrogen-vacancy spin in bulk diamond

The point-like nature and exquisite magnetic field sensitivity of the nitrogen vacancy (NV) center in diamond can provide information about the inner workings of magnetic nanocircuits in complement with traditional transport techniques. Here we use a single NV in bulk diamond to probe the stray field of a ferromagnetic nanowire controlled by spin transfer (ST) torques. We first report an unambiguous measurement of ST tuned, parametrically driven, large-amplitude magnetic oscillations. At the same time, we demonstrate that such magnetic oscillations alone can directly drive NV spin transitions, providing a potential new means of control. Finally, we use the NV as a local noise thermometer, observing strong ST damping of the stray field noise, consistent with magnetic cooling from room temperature to $\sim$150 K.Comment: 6 pages, 5 figures, plus supplementary informatio

Continuous and scalable polymer capsule processing for inertial fusion energy target shell fabrication using droplet microfluidics

High specification, polymer capsules, to produce inertial fusion energy targets, were continuously fabricated using surfactant-free, inertial centralisation, and ultrafast polymerisation, in a scalable flow reactor. Laser-driven, inertial confinement fusion depends upon the interaction of high-energy lasers and hydrogen isotopes, contained within small, spherical and concentric target shells, causing a nuclear fusion reaction at ~150 M°C. Potentially, targets will be consumed at ~1 M per day per reactor, demanding a 5000x unit cost reduction to ~$0.20, and is a critical, key challenge. Experimentally, double emulsions were used as templates for capsule-shells, and were formed at 20 Hz, on a fluidic chip. Droplets were centralised in a dynamic flow, and their shapes both evaluated, and mathematically modeled, before subsequent shell solidification. The shells were photo-cured individually, on-the-fly, with precisely-actuated, millisecond-length (70 ms), uniform-intensity UV pulses, delivered through eight, radially orchestrated light-pipes. The near 100% yield rate of uniform shells had a minimum 99.0% concentricity and sphericity, and the solidification processing period was significantly reduced, over conventional batch methods. The data suggest the new possibility of a continuous, on-the-fly, IFE target fabrication process, employing sequential processing operations within a continuous enclosed duct system, which may include cryogenic fuel-filling, and shell curing, to produce ready-to-use IFE targets

Factors Influencing Stored Oat Insect Populations in Eastern South Dakota

South Dakota has been one of the top two states in oat production over the past five years. During this time South Dakota’s average production was 12,914,036 quintals (88,784,000) bushels. The eastern one-fourth of the state and western Minnesota as well are known for the production of good quality and high test weight oats. Because of the high production in this region, much of the oats is marketed for a premium to millers and racehorse feed packers. It is estimated 10-15% of the total production in South Dakota is used for these two industries. Oats delivered to the elevator containing live insects can lose this premium because of their mere presence, The Food and Drug Administration ruled that grain is unfit for human consumption if it contains two percent insect damaged kernels. Oats can be graded weevily if it contains (a) two or more live weevils per representative lot, (b) 15 or more other live insects injurious to stored grain, including Angoumois moths (Grain Inspection Handbook 1980). In a survey of 360 elevators, 75% of the elevators are now applying a 0.2-2.9¢/quintal (1-20¢/bushel) discount for insect presence in all grains. The average discount was 0,8¢/quintal (5.2¢/ bushel) (Grain Quality Newsletter 1982). This agrees with a 100-elevator unpublished survey done by myself prior to the sampling of the oat bins. Seventy-seven percent of the elevators discounted for insects specifically in oats with a range of 0.2-3.6¢/quintal (1-25¢/bushel) and an average discount of 0.6¢/quintal (3.8¢/bushel). Milling premiums for the elevator operator were 0.4¢-.3.6¢/quintal (3-25¢/bushel) and an average of 1.7¢ (11.6¢). It has been also estimated that the farmer premium could be as high as 1.5¢/quintal (10¢/bushel), Most buyers of premium oats have indicated they refuse any oats containing live insects. The objectives of this research project were to (1) identify the major stored grain insects that infest stored oats in South Dakota, (2) to calculate insect densities over the main storage period, (3) to identify the factors that contribute to insect infestations in stored oats, and (4) to gather information that would provide for better recommendations on how to reduce insect infestations

C–F bond activation of perfluorinated arenes by a bioxazoline-derived N-heterocyclic carbene

The N-heterocyclic carbene IBioxMe4 enacts selective single and double C–F bond activation of octafluorotoluene and hexafluorobenzene, respectively. The formation of the fluoroarene substituted, zwitterionic imidazoliumolate products is consistent with a mechanism involving nucleophilic aromatic substitution and subsequent oxazoline ring opening by liberated fluoride

Type I error control in biomarker-stratified clinical trials

Biomarker-stratified clinical trials assess the biomarker signature of subjects and split them into subgroups so that treatment is of benefit to those who are likely to respond. Since multiple hypotheses are tested, it becomes important to control the type I error. Current methods control the false positive rate where one rejects the null hypothesis while in reality that was true. For two subgroups, the false positive rate is controlled across the two hypotheses as a Family Wise Error Rate (FWER) to an overall predetermined significance level