Connections on modules over quasi-homogeneous plane curves

Let k be an algebraically closed field of characteristic 0, and let $A = k[x,y]/(f)$ be a quasi-homogeneous plane curve. We show that for any graded torsion free A-module M, there exists a natural graded integrable connection, i.e. a graded A-linear homomorphism $\nabla: \operatorname{Der}_k(A) \to \operatorname{End}_k(M)$ that satisfy the derivation property and preserves the Lie product. In particular, a torsion free module N over the complete local ring $B = \hat A$ admits a natural integrable connection if A is a simple curve singularity, or if A is irreducible and N is a gradable module.Comment: AMS-LaTeX, 12 pages, minor changes. To appear in Comm. Algebr

The two-and three-point correlation functions of the polarized five-year WMAP sky maps

We present the two- and three-point real space correlation functions of the five-year WMAP sky maps, and compare the observed functions to simulated LCDM concordance model ensembles. In agreement with previously published results, we find that the temperature correlation functions are consistent with expectations. However, the pure polarization correlation functions are acceptable only for the 33GHz band map; the 41, 61, and 94 GHz band correlation functions all exhibit significant large-scale excess structures. Further, these excess structures very closely match the correlation functions of the two (synchrotron and dust) foreground templates used to correct the WMAP data for galactic contamination, with a cross-correlation statistically significant at the 2sigma-3sigma confidence level. The correlation is slightly stronger with respect to the thermal dust template than with the synchrotron template.Comment: 10 pages, 5 figures, published in ApJ. v2: New title, minor changes to appendix, and fixed some typos. v3: Matches version published in Ap

The fields of uniformly accelerated charges in de Sitter spacetime

The scalar and electromagnetic fields of charges uniformly accelerated in de Sitter spacetime are constructed. They represent the generalization of the Born solutions describing fields of two particles with hyperbolic motion in flat spacetime. In the limit Lambda -> 0, the Born solutions are retrieved. Since in the de Sitter universe the infinities I^+- are spacelike, the radiative properties of the fields depend on the way in which a given point of I^+- is approached. The fields must involve both retarded and advanced effects: Purely retarded fields do not satisfy the constraints at the past infinity I^-.Comment: 5 pages, 3 figures, RevTeX; Slightly expanded version of the paper published in Physical Review Letters. (The published version can be generated from the same TeX source.); problem with the postscript fixe

CMB likelihood approximation by a Gaussianized Blackwell-Rao estimator

We introduce a new CMB temperature likelihood approximation called the Gaussianized Blackwell-Rao (GBR) estimator. This estimator is derived by transforming the observed marginal power spectrum distributions obtained by the CMB Gibbs sampler into standard univariate Gaussians, and then approximate their joint transformed distribution by a multivariate Gaussian. The method is exact for full-sky coverage and uniform noise, and an excellent approximation for sky cuts and scanning patterns relevant for modern satellite experiments such as WMAP and Planck. A single evaluation of this estimator between l=2 and 200 takes ~0.2 CPU milliseconds, while for comparison, a single pixel space likelihood evaluation between l=2 and 30 for a map with ~2500 pixels requires ~20 seconds. We apply this tool to the 5-year WMAP temperature data, and re-estimate the angular temperature power spectrum, $C_{\ell}$, and likelihood, L(C_l), for l<=200, and derive new cosmological parameters for the standard six-parameter LambdaCDM model. Our spectrum is in excellent agreement with the official WMAP spectrum, but we find slight differences in the derived cosmological parameters. Most importantly, the spectral index of scalar perturbations is n_s=0.973 +/- 0.014, 1.9 sigma away from unity and 0.6 sigma higher than the official WMAP result, n_s = 0.965 +/- 0.014. This suggests that an exact likelihood treatment is required to higher l's than previously believed, reinforcing and extending our conclusions from the 3-year WMAP analysis. In that case, we found that the sub-optimal likelihood approximation adopted between l=12 and 30 by the WMAP team biased n_s low by 0.4 sigma, while here we find that the same approximation between l=30 and 200 introduces a bias of 0.6 sigma in n_s.Comment: 10 pages, 7 figures, submitted to Ap

Keynesian economics and the Oslo School

The economic crisis of the 1930’s hit Norway when Ragnar Frisch returned from the US to accept a professorship at University of Oslo. On his return he wrote newspaper articles proposing tax relief and monetary policies to fight the economic crisis. Frisch abandoned his monetary policies and developed his Oslo School emphasising mathematical models, econometrics, national accounts, and detailed state governance. For the next four decades this School dominated economic policy in Norway where market forces had been substituted with administrative decision making. Keynes, with his General Theory, pointed out that a market economy with an active government can secure full employment. When the ideas of the Oslo School were challenged at the end of the 1970’s, by academics and through the poor performance of the economy, it collapsed. A decentralised market economy was reintroduced and The Keynesian paradigm emerged as the preferred theory compared to the approach of the Oslo School.

Full or partial outdoor rearing of slaughter pigs – effects on performance, carcass quality and nutrient load

An experiment with slaughter pigs from weaning to slaughter including five treatments and five replicates was carried out at the Danish organic experimental station, Rugballegård. Treatments included full or partial outdoor rearing of the pigs, and the replicates covered the seasonal effects. Pigs fed ad libitum indoors had a significantly lower feed consumption (5 MJ ME /kg gain), a lower lean percentage (2.3% points), and a higher backfat depth (1.1 mm, P < 0.05) than pigs fed ad libitum outdoors. Compared with outdoor pigs fed ad libitum, restricted feeding outdoors resulted in a significantly lower daily gain (107 g), a lower feed consumption (6.3 MJ ME/kg gain), higher lean percentage (2.1% points), and a reduced backfat (1.8 mm) (P <0.001). The content of soil nitrogen was considerably higher than for the soil outside the paddocks. Despite a considerable variation within the paddocks, N was distributed throughout the paddock. The present investigation highlights the fact that outdoor rearing of organic finishers may be a competitive option even in a temperate climate and all year round

In field N transfer, build-up, and leaching in ryegrass-clover mixtures

Two field experiments investigating dynamics in grass-clover mixtures were conducted, using 15N- and 14C-labelling to trace carbon (C) and nitrogen (N) from grass (Lolium perenne L.) and clover (Trifolium repens L. and Trifolium pratense L.). The leaching of dissolved inorganic nitrogen (DIN), as measured in pore water sampled by suction cups, increased during the autumn and winter, whereas the leaching of dissolved organic nitrogen (DON) was fairly constant during this period. Leaching of 15N from the sward indicated that ryegrass was the direct source of less than 1-2 percent of the total N leaching measured, whereas N dynamics pointed to clover as an important contributor to N leaching. Sampling of roots indicates that the dynamics in smaller roots were responsible for N and C build-up in the sward, and that N became available for transfer among species and leaching from the root zone. The bi-directional transfer of N between ryegrass and clover could however not be explained only by root turnover. Other processes like direct uptake of organic N compounds, may have contributed

Tournaments with prize-setting agents

In many tournaments it is the contestants themselves who determine reward allocation. Labor-union members bargain over wage distribution, and many firms allow self-managed teams to freely determine internal resource allocation, incentive structure, and division of labour. We analyze, and test experimentally, a rank-order tournament where heterogenous agents determine the spread between winner prize and looser prize. We investigate the relationship between prize spread, uncertainty (i.e. noise between e¤ort and performance), heterogeneity and effort. The paper challenges well-known results from tournament theory. We find that a large prize spread is associated with low degree of uncertainty and high degree of heterogeneity, and that heterogeneity triggers effort. By and large, our real-effort experiment supports the theoretical predictions.Rank-order tournament; prize spread; ability-difference

The Rise and Fall of the Oslo School

In 1931 Ragnar Frisch became professor at the University of Oslo. By way of his research, a new study programme and new staff he created the ”Oslo School”, characterised by mathematical modelling, econometrics, economic planning and scepticism towards the market economy. Consequently, detailed state economic planning and governance dominated Norwegian economic policy for three decades after WWII. In the 1970s the School’s dominance came to an end when the belief in competitive markets gained a foothold and the economy had poor performance. As a result a decentralized market economy was reintroduced. However, mathematical modelling and econometrics remain in the core of most economic programmes.