NuSTAR observation of the Arches cluster: X-ray spectrum extraction from a 2D image

The NuSTAR mission performed a long (200 ks) observation of the Arches stellar cluster in 2015. The emission from the cluster represents a mixture of bright thermal (kT~2 keV) X-rays and the extended non-thermal radiation of the molecular cloud around the cluster. In this work we describe the method used to decouple spatially confused emission of the stellar cluster and the molecular cloud in the NuSTAR data.Comment: 5 pages, 4 figures, accepted contribution to the 11th INTEGRAL Conference, "Gamma-Ray Astrophysics in Multi-Wavelength Perspective", 10-14 October 2016, Amsterdam, The Netherlands (<a href="https://pos.sissa.it/285/">HTTP link

The W(sl(N+3),sl(3)) algebras and their contractions to W3

We construct the nonlinear $W(sl(N+3),sl(3))$ algebras and find the spectrum of values of the central charge that gives rise, by contracting the $W(sl(N+3),sl(3))$ algebras, to a $W_3$ algebra belonging to the coset $W((sl(N+3),sl(3))/(u(1)\oplus sl(N))$. Part of the spectrum was conjectured before, but part of it is given here for the first time. Using the tool of embedding the $W(sl(N+3),sl(3))$ algebras into linearizing algebras, we construct new realizations of $W_3$ modulo null fields. The possibility to predict, within the conformal linearization framework, the central charge spectrum for minimal models of the nonlinear $W(sl(N+3),sl(3))$ algebras is discussed at the end.Comment: 12 pages, 2 tables, LaTeX, minor typos corrected on pages 4 and

The impact of coffee market reforms on producer prices and price transmission

This paper evaluates the impact of coffee sector reforms during late 1980s and early 1990s on coffee growers in the main coffee producing countries. Earlier evidence suggests that the reforms increased the share of producer prices in the world price of coffee. This hypothesis is tested in the paper with the help of cointegration analysis, and the results show that in most countries the longterm producer price share has indeed increased substantially after the liberalization. Moreover, the results suggest that the reforms induced a closer cointegrating relationship between grower prices and world market prices. Finally, estimation of an error-correction model reveals that short-run transmission of price signals from the world market to domestic producers has improved, such that domestic prices adjust faster today to world price fluctuations than they did prior to the reforms. However, there is some evidence of asymmetries in the way positive and negative world price changes are transmitted to domestic markets.Payment Systems&Infrastructure,Markets and Market Access,Insurance&Risk Mitigation,Environmental Economics&Policies,Economic Theory&Research,Access to Markets,Markets and Market Access,Crops&Crop Management Systems,Environmental Economics&Policies,Economic Theory&Research

The impact of coffee market reforms on producer prices and price transmission

This paper evaluates the impact of coffee sector reforms during late 1980s and early 1990s on coffee growers in the main coffee producing countries. Earlier evidence suggests that the reforms increased the share of producer prices in the world price of coffee. This hypothesis is tested in the paper with the help of cointegration analysis, and the results show that in most countries the long-term producer price share has indeed increased substantially after the liberalization. Moreover, the results suggest that the reforms induced a closer cointegrating relationship between grower prices and world market prices. Finally, estimation of an error-correction model reveals that short-run transmission of price signals from the world market to domestic producers has improved, such that domestic prices adjust faster today to world price fluctuations than they did prior to the reforms. However, there is some evidence of asymmetries in the way positive and negative world price changes are transmitted to domestic markets.International Relations/Trade,

Hamiltonian structure and coset construction of the supersymmetric extensions of N=2 KdV hierarchy

A manifestly N=2 supersymmetric coset formalism is applied to analyse the "fermionic" extensions of N=2 $a=4$ and $a=-2$ KdV hierarchies. Both these hierarchies can be obtained from a manifest N=2 coset construction. This coset is defined as the quotient of some local but non-linear superalgebra by a $\hat{U(1)}$ subalgebra. Three superextensions of N=2 KdV hierarchy are proposed, among which one seems to be entirely new.Comment: 11 pages, Latex, a few modifications in the tex

Null Fields Realizations of W3W_3 from W(sl(4),sl(3))W(sl(4),sl(3)) and W(sl(3∣1),sl(3))W(sl(3|1),sl(3)) Algebras

We consider the nonlinear algebras $W(sl(4),sl(3))$ and $W(sl(3|1),sl(3))$ and find their realizations in terms of currents spanning conformal linearizing algebras. The specific structure of these algebras, allows us to construct realizations modulo null fields of the $W_3$ algebra that lies in the cosets $W(sl(4),sl(3))/u(1)$ and $W(sl(3|1),sl(3))/u(1)$. Such realizations exist for the following values of the $W_3$ algebra central charge: $c_W=-30,-40/7,-98/5,-2$. The first two values are listed for the first time, whereas for the remaining values we get the new realizations in terms of an arbitrary stress tensor and $u(1)\times sl(2)$ affine currents.Comment: Submitted to Phys. Lett. B; PACS-no 11.30.L