Need, Greed and Noise: Competing Strategies in a Trading Model

We study an economic model where agents trade a variety of products by using one of three competing rules: "need", "greed" and "noise". We find that the optimal strategy for any agent depends on both product composition in the overall market and composition of strategies in the market. In particular, a strategy that does best on pairwise competition may easily do much worse when all are present, leading, in some cases, to a "paper, stone, scissors" circular hierarchy.Comment: 10 pages, 6 figure

The onset of the North Atlantic Igneous Province in a rifting perspective

The processes that led to the onset and evolution of the North Atlantic Igneous Province IN A I P) have been a theme of debate ill the past decades. A popular theory has been that the impingement on the lower lithosphere of a hot mantle plume (the 'Ancestral Iceland' plume) initiated the first voluminous outbursts of lava and initiated rifling in the North Atlantic area in Early Palaeogene times. Here we review previous studies in order to set the NAIP magmatism in a time-space context. We suggest that global plate reorganizations and lithospheric extension across old orogenic fronts and/or suture zones, aided by other processes in the mantle (e.g. local or regional scale upwellings prior to and during the final Early Eocene rifting), played a role in the generation of the igneous products recorded ill the NAIP for this period. These events gave rise to the extensive Paleocene and Eocene igneous rocks in W Greenland, NW Britain and at the conjugate E Greenland-NW European margins. Many of the relatively large magmatic centres of the NAIP were associated with transient and geographically confined doming in Early Paleocene times prior to the final break-up of the North Atlantic area

Physics of Fashion Fluctuations

We consider a market where many agents trade many different types of products with each other. We model development of collective modes in this market, and quantify these by fluctuations that scale with time with a Hurst exponent of about 0.7. We demonstrate that individual products in the model occationally become globally accepted means of exchange, and simultaneously become very actively traded. Thus collective features similar to money spontaneously emerge, without any a priori reason.Comment: 9 pages RevTeX, 5 Postscript figure

Scaling in Fracture and Refreezing of Sea Ice

Sea ice breaks up and regenerates rapidly during winter conditions in the Arctic. Analyzing satellite data from the Kara Sea, we find that the average ice floe size depends on weather conditions. Nevertheless, the frequency of floes of size $A$ is a power law, $N\sim A^{-\tau}$, where $\tau=1.6\pm 0.2$, for $A$ less than approximately 100 $km^2$. This scale-invariant behaviour suggests a competition between fracture due to strains in the ice field and refreezing of the fractures. A cellular model for this process gives results consistent with observations.Comment: Physica A (in press

Exploiting Evolution for an Adaptive Drift-Robust Classifier in Chemical Sensing

Gas chemical sensors are strongly affected by drift, i.e., changes in sensors' response with time, that may turn statistical models commonly used for classification completely useless after a period of time. This paper presents a new classifier that embeds an adaptive stage able to reduce drift effects. The proposed system exploits a state-of-the-art evolutionary strategy to iteratively tweak the coefficients of a linear transformation able to transparently transform raw measures in order to mitigate the negative effects of the drift. The system operates continuously. The optimal correction strategy is learnt without a-priori models or other hypothesis on the behavior of physical-chemical sensors. Experimental results demonstrate the efficacy of the approach on a real problem

Redefining hypoglycemia in clinical trials: validation of definitions recently adopted by the American Diabetes Association/European Association for the study of diabetes

OBJECTIVE The purpose of this study was to determine if the International Hypoglycemia Study Group (IHSG) level 2 low glucose definition could identify clinically relevant hypoglycemia in clinical trials and offer value as an end point for future trials. RESEARCH DESIGN AND METHODS A post hoc analysis of the SWITCH (SWITCH 1: n = 501, type 1 diabetes; SWITCH 2: n = 721, type 2 diabetes) and the Trial Comparing Cardiovascular Safety of Insulin Degludec versus Insulin Glargine in Patients with Type 2 Diabetes at High Risk of Cardiovascular Events (DEVOTE; n = 7,637, type 2 diabetes) using the IHSG low glucose definitions. Patients in all trials were randomized to either insulin degludec or insulin glargine 100 units/mL. In the main analysis, the following definitions were compared: 1) American Diabetes Association (ADA) 2005 (plasma glucose [PG] confirmed ≤3.9 mmol/L with symptoms); and 2) IHSG level 2 (glucose confirmed <3.0 mmol/L). RESULTS In SWITCH 2, the estimated rate ratios of hypoglycemic events indicated increasing differences between treatments with decreasing PG levels until 3.0 mmol/L, following which no additional treatment differences were observed. In SWITCH 2, the IHSG level 2 definition produced a rate ratio that was lower than the ADA 2005 definition. Similar results were observed for the SWITCH 1 trial. CONCLUSIONS The IHSG level 2 definition was validated in a series of clinical trials, demonstrating its ability to discriminate between basal insulins. This definition is therefore recommended to be uniformly adopted by regulatory bodies and used in future clinical trials

Lower rates of hypoglycaemia in older individuals with type 2 diabetes using insulin degludec versus insulin glargine U100 : results from SWITCH 2

Aim This study aimed to investigate the safety of insulin degludec (degludec) in relation to age and risk of hypoglycaemia post hoc in individuals with type 2 diabetes (T2D) (SWITCH 2 trial). Methods In this crossover study, individuals with T2D who were at risk of hypoglycaemia were randomized to double‐blind treatment with degludec or insulin glargine 100 units/mL (glargine U100) ± oral antidiabetic drugs. After 32 weeks, patients crossed over to the other treatment. Primary endpoint was number of overall severe (positively adjudicated) or glucose‐confirmed (plasma glucose <56 mg/dL; 3.1 mmol/L) symptomatic hypoglycaemia events during the two 16‐week maintenance periods. Results For individuals ≤65 (n = 450) and >65 (n = 270) years, baseline median (range) duration of diabetes was 12 (1–40) vs 15 (1–54) years, mean HbA1c was 7.7% vs 7.4% and mean estimated glomerular filtration rate was 87.0 vs 63.7 mL/min/1.73 m2, respectively. No significant differences in HbA1c reduction were seen in individuals ≤65 or >65 years. During both maintenance periods, treatment with degludec lowered rates of hypoglycaemia (overall/nocturnal symptomatic) vs those with glargine U100 in individuals ≤65 (31% vs 43%) and >65 (30% vs 41%) years. With degludec and glargine U100, respectively, six vs nine severe hypoglycaemic events occurred in individuals ≤65 years and four vs eight events occurred in those >65 years. Adverse event rates were 3.2 and 3.3 events/patient‐year for individuals ≤65 years and were 3.5 and 4.1 events/patient‐year for individuals >65 years with degludec and glargine U100, respectively. Conclusion Treatment with degludec was safe and effective, with a frequency of hypoglycaemia lower than that with glargine U100 in both younger and older individuals (>65 years) with T2D

Neutron scattering and molecular correlations in a supercooled liquid

We show that the intermediate scattering function $S_n(q,t)$ for neutron scattering (ns) can be expanded naturely with respect to a set of molecular correlation functions that give a complete description of the translational and orientational two-point correlations in the liquid. The general properties of this expansion are discussed with special focus on the $q$-dependence and hints for a (partial) determination of the molecular correlation functions from neutron scattering results are given. The resulting representation of the static structure factor $S_n(q)$ is studied in detail for a model system using data from a molecular dynamics simulation of a supercooled liquid of rigid diatomic molecules. The comparison between the exact result for $S_n(q)$ and different approximations that result from a truncation of the series representation demonstrates its good convergence for the given model system. On the other hand it shows explicitly that the coupling between translational (TDOF) and orientational degrees of freedom (ODOF) of each molecule and rotational motion of different molecules can not be neglected in the supercooled regime.Further we report the existence of a prepeak in the ns-static structure factor of the examined fragile glassformer, demonstrating that prepeaks can occur even in the most simple molecular liquids. Besides examining the dependence of the prepeak on the scattering length and the temperature we use the expansion of $S_n(q)$ into molecular correlation functions to point out intermediate range orientational order as its principle origin.Comment: 13 pages, 7 figure

Cardiovascular risk estimation and eligibility for statins in primary prevention comparing different strategies.

Recommendations for statin use for primary prevention of coronary heart disease (CHD) are based on estimation of the 10-year CHD risk. It is unclear which risk algorithm and guidelines should be used in European populations. Using data from a population-based study in Switzerland, we first assessed 10-year CHD risk and eligibility for statins in 5,683 women and men 35 to 75 years of age without cardiovascular disease by comparing recommendations by the European Society of Cardiology without and with extrapolation of risk to age 60 years, the International Atherosclerosis Society, and the US Adult Treatment Panel III. The proportions of participants classified as high-risk for CHD were 12.5% (15.4% with extrapolation), 3.0%, and 5.8%, respectively. Proportions of participants eligible for statins were 9.2% (11.6% with extrapolation), 13.7%, and 16.7%, respectively. Assuming full compliance to each guideline, expected relative decreases in CHD deaths in Switzerland over a 10-year period would be 16.4% (17.5% with extrapolation), 18.7%, and 19.3%, respectively; the corresponding numbers needed to treat to prevent 1 CHD death would be 285 (340 with extrapolation), 380, and 440, respectively. In conclusion, the proportion of subjects classified as high risk for CHD varied over a fivefold range across recommendations. Following the International Atherosclerosis Society and the Adult Treatment Panel III recommendations might prevent more CHD deaths at the cost of higher numbers needed to treat compared with European Society of Cardiology guidelines

Channel diffusion of sodium in a silicate glass

We use classical molecular dynamics simulations to study the dynamics of sodium atoms in amorphous Na$_2$O-4SiO$_2$. We find that the sodium trajectories form a well connected network of pockets and channels. Inside these channels the motion of the atoms is not cooperative but rather given by independent thermally activated hops of individual atoms between the pockets. By determining the probability that an atom returns to a given starting site, we show that such events are not important for the dynamics of this system.Comment: 10 pages of Latex, 5 figures, one figure added, text expande