Land issues and poverty reduction: Requirements for lasting peace in Sudan and Afghanistan

Poverty reduction, Hunger, Poverty, Underdevelopment, Agricultural growth, War and peace,

Quantum error correction may delay, but also cause, entanglement sudden death

Dissipation may cause two initially entangled qubits to evolve into a separable state in a finite time. This behavior is called entanglement sudden death (ESD). We study to what extent quantum error correction can combat ESD. We find that in some cases quantum error correction can delay entanglement sudden death but in other cases quantum error correction may cause ESD for states that otherwise do not suffer from it. Our analysis also shows that fidelity may not be the best measure to compare the efficiency of different error correction codes since the fidelity is not directly coupled to a state's remaining entanglement.Comment: 3 figure

Social differentials in speed-premium effects in childbearing in Sweden

In Sweden, parents receive a parental-leave allowance of a high percentage of their pre-birth salary for about a year in connection with any birth. (The percentage has changed over time, as has the period for which it is paid. For a birth that appears in 2005, parents get 80% of the salary for thirteen months.) If they space their births sufficiently closely, they avoid a reduction in the allowance caused by any reduced income earned between the births. The gain is popularly called a “speed premium”. After some precursors in legal practice, this rule was made statutory in 1980 and the “eligibility interval” was then set to 24 months. In 1986, it was extended to more attainable thirty months. In previous work we have displayed a corresponding speed-up effect in childbearing for Swedish-born women. This change in behavior is of general interest since it is clear evidence of a causal effect of a policy change on childbearing behavior. In the present paper, we study how this change in behavior was adopted in different social strata of the Swedish population. We examine whether the speed-up of childbearing differed by educational attainment and by country of origin, to see whether some social groups reacted faster or more strongly to the policy change than others. We cannot find any important difference in the reaction to the introduction of the “speed premium” between educational groups of Swedish-born parents. Similarly, we find no important difference in the mode of reaction between Swedish-born women and Nordic immigrants to the country. By contrast, immigrants from non-Nordic countries hardly seem to have reacted to the “speed premium”.Sweden, childbearing

UTILIZATION OF THE ICELANDIC COD STOCK IN A MULTISPECIES CONTEXT

The purpose of this paper is to discuss rules for deciding Total Allowable Catch (TAC) for Icelandic cod. For this purpose, a bioeconomic model describing harvesting and processing of cod, capelin, and shrimp in the Icelandic marine ecosystem is constructed and estimated. The model is used to analyze the probable effects of harvesting strategies on biomass, catch, and economic benefits from the exploitation of these species. Simulations are used to investigate probability profiles of biological and economic variables, taking into account inaccuracies in assessments and uncertainties in predictions. Optimal harvesting strategies are also investigated using a deterministic version of the model and taking into account problems of unemployment, overcapacity, and aversion to fluctuations in consumption. The analysis shows that it is beneficial to reduce fishing from the cod stock in order to allow the stock to recover to its optimum size. This increase in the cod stock will result in big decreases in the catch of capelin and shrimp.Resource /Energy Economics and Policy,

Borel Degenerations of Arithmetically Cohen-Macaulay curves in P^3

We investigate Borel ideals on the Hilbert scheme components of arithmetically Cohen-Macaulay (ACM) codimension two schemes in P^n. We give a basic necessary criterion for a Borel ideal to be on such a component. Then considering ACM curves in P^3 on a quadric we compute in several examples all the Borel ideals on their Hilbert scheme component. Based on this we conjecture which Borel ideals are on such a component, and for a range of Borel ideals we prove that they are on the component.Comment: 20 pages, shorter and more effective versio

Entanglement invariant for the double Jaynes-Cummings model

We study entanglement dynamics between four qubits interacting through two isolated Jaynes-Cummings hamiltonians, via the entanglement measure based on the wedge product. We compare the results with similar results obtained using bipartite concurrence resulting in what is referred to as "entanglement sudden death". We find a natural entanglement invariant under evolution demonstrating that entanglement sudden death is caused by ignoring (tracing over) some of the system's degrees of freedom that become entangled through the interaction.Comment: Sec. V has largely been rewritten. An error pertaining to the entanglement invariant has been corrected and a correct invariant valid for a much larger set of states have been found, Eq. (25

Peacebuilding in post-war situations: Lessons for Sudan

This report examines lessons from peacebuilding efforts during the last decade or so that are relevant to the current challenges in Sudan. While there is an emphasis on governance interventions, it is argued more generally that three factors will be crucial for building peace in Sudan. First, the peace agreement between the Government of Sudan and the Sudan People's Liberation Movement must be transformed into a deal that can be "owned" not only be the parties that signed the agreement, but also by those who did not take part in the talks, including civil society and the Sudanese population at large. Second, sustained and focused international attention will be critical to maintain the momentum of the peace process. As the reality of peacebuilding lies in power and politics, interventions by outsiders must also be sensitive to the overall politics of the process. Third, regional conflict in the Horn of Africa has more often than not been the by-product of internal conflict. To sustain the framework of peace in Sudan, regional states must be convinced that peace in Sudan is a collective good that can reduce cross-border problems, ranging from ideologies and refugees to the export of arms and violence. A main determinant will be the approaches by the Sudanese parties themselves towards neighbouring states

Quantum theory of light and noise polarization in nonlinear optics

We present a consistent quantum theory of the electromagnetic field in nonlinearly responding causal media, with special emphasis on $\chi^{(2)}$ media. Starting from QED in linearly responding causal media, we develop a method to construct the nonlinear Hamiltonian expressed in terms of the complex nonlinear susceptibility in a quantum mechanically consistent way. In particular we show that the method yields the nonlinear noise polarization, which together with the linear one is responsible for intrinsic quantum decoherence.Comment: 4 pages, no figure

Results of REXUS12's Suaineadh Experiment : Deployment of a spinning space web in micro gravity conditions

On the 19th of March 2012, the Suaineadh experiment was launched onboard the sounding rocket REXUS12 (Rocket Experiments for University Students) from the Swedish launch base ESRANGE in Kiruna. The Suaineadh experiment served as a technology demonstrator for a space web deployed by a spinning assembly. The deployment of this web is a stepping stone for the development of ever larger structures in space. Such a structure could serve as a substructure for solar arrays, transmitters and/or antennas. The team was comprised of students from the University of Strathclyde (Glasgow, UK), the University of Glasgow (Glasgow, UK) and the Royal Institute of Technology (Stockholm, Sweden), designing, manufacturing and testing the experiment over the past 24 months. Following launch, the experiment was ejected from the ejection barrel located within the nosecone of the rocket. Centrifugal forces acting upon the space webs spinning assembly were used to stabilise the experiment’s platform. A specifically designed spinning reaction wheel, with an active control method, was used. Once the experiment’s motion was controlled, a 2 m by 2 m space web is released. Four daughter sections situated in the corners of the square web served as masses to stabilise the web due to the centrifugal forces acting on them. The four daughter sections contained inertial measurement units (IMUs). Each IMU provided acceleration and velocity measurements in all three directions. Through this, the positions of the four corners could be found through integration with respect to known time of the accelerations and rotations. Furthermore, four cameras mounted on the central hub section captured high resolution imagery of the deployment process. After the launch of REXUS12, the recovery helicopter was unable to locate the ejected experiment, but 22 pictures were received over the wireless connection between the experiment and the rocket. The last received picture was taken at the commencement of web deployment. Inspection of these pictures allowed the assumption that the experiment was fully functional after ejection, but perhaps through tumbling of either the experiment or the rocket, the wireless connection was interrupted. A recovery mission in the middle of August was only able to find the REXUS12 motor and the payload impact location

Sparse Nerves in Practice

Topological data analysis combines machine learning with methods from algebraic topology. Persistent homology, a method to characterize topological features occurring in data at multiple scales is of particular interest. A major obstacle to the wide-spread use of persistent homology is its computational complexity. In order to be able to calculate persistent homology of large datasets, a number of approximations can be applied in order to reduce its complexity. We propose algorithms for calculation of approximate sparse nerves for classes of Dowker dissimilarities including all finite Dowker dissimilarities and Dowker dissimilarities whose homology is Cech persistent homology. All other sparsification methods and software packages that we are aware of calculate persistent homology with either an additive or a multiplicative interleaving. In dowker_homology, we allow for any non-decreasing interleaving function $\alpha$. We analyze the computational complexity of the algorithms and present some benchmarks. For Euclidean data in dimensions larger than three, the sizes of simplicial complexes we create are in general smaller than the ones created by SimBa. Especially when calculating persistent homology in higher homology dimensions, the differences can become substantial