Prosecuting the main perpetrators of international crimes in Eritrea: Possibilities under international law

A growing international consensus has emerged in the last few decades on the need to prosecute egregious violations of international law. In this regard, the establishment of the International Criminal Court (ICC) is seen as a landmark development in the global protection of international human rights and humanitarian law standards. Since its independence in 1991, Eritrea has experienced heinous violations of international law. The violations amount to international core crimes, as defined by the ICC Statute and customary international law. These include crimes against humanity, war crimes and the crime of aggression. There are consistent reports, as well as documentary and testimonial evidence from reliable sources on this. Accordingly, a number of high-ranking government officials may be reasonably suspected of involvement in the perpetration of international crimes in Eritrea. However, Eritrea is not a state party to the ICC Statute and this means that many of the international crimes perpetrated in the country may not fall under the jurisdiction of the ICC. On the other hand, violations are continuing with impunity, as there are no effective domestic remedies to rectify the problem, giving rise to the need for immediate intervention by the international community. The article discusses the legal implications of the ICC Statute with regard to international crimes committed in Eritrea before and after the coming into effect of the Statute. Drawing on the latest developments of international criminal law, it explores possible options for the prosecution of the main perpetrators of international crimes pursuant to Security Council referral as stipulated under article 13(b) of the ICC Statute

Ninja data analysis with a detection pipeline based on the Hilbert-Huang Transform

The Ninja data analysis challenge allowed the study of the sensitivity of data analysis pipelines to binary black hole numerical relativity waveforms in simulated Gaussian noise at the design level of the LIGO observatory and the VIRGO observatory. We analyzed NINJA data with a pipeline based on the Hilbert Huang Transform, utilizing a detection stage and a characterization stage: detection is performed by triggering on excess instantaneous power, characterization is performed by displaying the kernel density enhanced (KD) time-frequency trace of the signal. Using the simulated data based on the two LIGO detectors, we were able to detect 77 signals out of 126 above SNR 5 in coincidence, with 43 missed events characterized by signal to noise ratio SNR less than 10. Characterization of the detected signals revealed the merger part of the waveform in high time and frequency resolution, free from time-frequency uncertainty. We estimated the timelag of the signals between the detectors based on the optimal overlap of the individual KD time-frequency maps, yielding estimates accurate within a fraction of a millisecond for half of the events. A coherent addition of the data sets according to the estimated timelag eventually was used in a characterization of the event.Comment: Accepted for publication in CQG, special issue NRDA proceedings 200

Black Hole Mergers and Unstable Circular Orbits

We describe recent numerical simulations of the merger of a class of equal mass, non-spinning, eccentric binary black hole systems in general relativity. We show that with appropriate fine-tuning of the initial conditions to a region of parameter space we denote the threshold of immediate merger, the binary enters a phase of close interaction in a near-circular orbit, stays there for an amount of time proportional to logarithmic distance from the threshold in parameter space, then either separates or merges to form a single Kerr black hole. To gain a better understanding of this phenomena we study an analogous problem in the evolution of equatorial geodesics about a central Kerr black hole. A similar threshold of capture exists for appropriate classes of initial conditions, and tuning to threshold the geodesics approach one of the unstable circular geodesics of the Kerr spacetime. Remarkably, with a natural mapping of the parameters of the geodesic to that of the equal mass system, the scaling exponent describing the whirl phase of each system turns out to be quite similar. Armed with this lone piece of evidence that an approximate correspondence might exist between near-threshold evolution of geodesics and generic binary mergers, we illustrate how this information can be used to estimate the cross section and energy emitted in the ultra relativistic black hole scattering problem. This could eventually be of use in providing estimates for the related problem of parton collisions at the Large Hadron Collider in extra dimension scenarios where black holes are produced.Comment: 16 pages, 12 figures; updated to coincide with journal versio

Ecology and Management of Pemphigus betae (Hemiptera: Aphididae) in Sugar Beet

Published ArticlePemphigus betae Doane (Hemiptera: Aphididae), is a sporadic pest of sugar beet (Beta vulgaris L. var. vulgaris) in all major sugar beet production regions of North America. These oval-shaped, pale-yellowish insects, with a body length ranging from 1.9–2.4mm, secrete a waxy material, giving their subterranean colonies a moldy appearance. Poplars in the genus Populus L. are the preferred primary hosts, while sugar beet and certain weed species, such as common lambsquarters (Chenopodium album L.) and kochia (Kochia scoparia (L.)), are among the secondary hosts. Pemphigus betae has a complex and varied life cycle and is usually heteroecious and holocyclic, although anholocyclic apterae are known to overwinter in the soil. Heavy infestations of this aphid can induce significant reductions in yield, sugar content, and recoverable sugar. Under conditions of extreme stress and heavy infestations, the alienicolae can induce stunting, chlorosis, wilting, and even death of sugar beet plants. Accurately establishing population densities for sugarbeet root aphids presents a challenge, because the economic important stage of this insect is subterranean. However, use of a fall root rating index aids in estimating relative population densities. Furthermore, root aphids are especially difficult to control by means of conventional insecticides. For this reason, integrated pest management tactics, including the use of host plant resistance, cultural control techniques, and the use of natural enemies, should take precedence

Simulation of Binary Black Hole Spacetimes with a Harmonic Evolution Scheme

A numerical solution scheme for the Einstein field equations based on generalized harmonic coordinates is described, focusing on details not provided before in the literature and that are of particular relevance to the binary black hole problem. This includes demonstrations of the effectiveness of constraint damping, and how the time slicing can be controlled through the use of a source function evolution equation. In addition, some results from an ongoing study of binary black hole coalescence, where the black holes are formed via scalar field collapse, are shown. Scalar fields offer a convenient route to exploring certain aspects of black hole interactions, and one interesting, though tentative suggestion from this early study is that behavior reminiscent of "zoom-whirl" orbits in particle trajectories is also present in the merger of equal mass, non-spinning binaries, with appropriately fine-tuned initial conditions.Comment: 16 pages, 14 figures; replaced with published versio

Radiation from low-momentum zoom-whirl orbits

We study zoom-whirl behaviour of equal mass, non-spinning black hole binaries in full general relativity. The magnitude of the linear momentum of the initial data is fixed to that of a quasi-circular orbit, and its direction is varied. We find a global maximum in radiated energy for a configuration which completes roughly one orbit. The radiated energy in this case exceeds the value of a quasi-circular binary with the same momentum by 15%. The direction parameter only requires minor tuning for the localization of the maximum. There is non-trivial dependence of the energy radiated on eccentricity (several local maxima and minima). Correlations with orbital dynamics shortly before merger are discussed. While being strongly gauge dependent, these findings are intuitive from a physical point of view and support basic ideas about the efficiency of gravitational radiation from a binary system.Comment: 9 pages, 6 figures, Amaldi8 conference proceedings as publishe

Axial flow fan performance in a forced draught air-cooled heat exchanger for a sCO2 Brayton cycle

An axial flow cooling fan has been designed for use in a concentrated solar power plant. The plant is based on a supercritical carbon dioxide (sCO2) Brayton cycle, and uses a forced draft air-cooled heat exchanger (ACHE) for cooling. The fan performance has been investigated using both computational fluid dynamics (CFD) and scaled fan tests. This paper presents a CFD model that integrates the fan with the heat exchanger. The objective is to establish a foundation for similar models and to contribute to the development of efficient ACHE units designed for sCO2 power cycles. The finned-tube bundle is simplified, with a Porous Media Model representing the pressure drop through the bundle. Pressure inlet and -outlet boundary conditions are used, meaning the air flow rate is solved based on the fan and tube bundle interaction. The flow rate predicted by the CFD model is 0.5% higher than the analytical prediction, and 3.6% lower than the design value, demonstrating that the assumptions used in the design procedure are reasonable. The plenum height is also found to affect the flow rate, with shorter plenums resulting in higher flow rates and fan efficiencies, and longer plenums resulting in more uniform cooling air flow

Learning about compact binary merger: the interplay between numerical relativity and gravitational-wave astronomy

Activities in data analysis and numerical simulation of gravitational waves have to date largely proceeded independently. In this work we study how waveforms obtained from numerical simulations could be effectively used within the data analysis effort to search for gravitational waves from black hole binaries. We propose measures to quantify the accuracy of numerical waveforms for the purpose of data analysis and study how sensitive the analysis is to errors in the waveforms. We estimate that ~100 templates (and ~10 simulations with different mass ratios) are needed to detect waves from non-spinning binary black holes with total masses in the range 100 Msun < M < 400 Msun using initial LIGO. Of course, many more simulation runs will be needed to confirm that the correct physics is captured in the numerical evolutions. From this perspective, we also discuss sources of systematic errors in numerical waveform extraction and provide order of magnitude estimates for the computational cost of simulations that could be used to estimate the cost of parameter space surveys. Finally, we discuss what information from near-future numerical simulations of compact binary systems would be most useful for enhancing the detectability of such events with contemporary gravitational wave detectors and emphasize the role of numerical simulations for the interpretation of eventual gravitational-wave observations.Comment: 19 pages, 12 figure

Simulation of Asymptotically AdS5 Spacetimes with a Generalized Harmonic Evolution Scheme

Motivated by the gauge/gravity duality, we introduce a numerical scheme based on generalized harmonic evolution to solve the Einstein field equations on asymptotically anti-de Sitter (AdS) spacetimes. We work in global AdS5, which can be described by the (t,r,\chi,\theta,\phi) spherical coordinates adapted to the R{\times}S3 boundary. We focus on solutions that preserve an SO(3) symmetry that acts to rotate the 2-spheres parametrized by \theta,\phi. In the boundary conformal field theory (CFT), the way in which this symmetry manifests itself hinges on the way we choose to embed Minkowski space in R{\times}S3. We present results from an ongoing study of prompt black hole formation via scalar field collapse, and explore the subsequent quasi-normal ringdown. Beginning with initial data characterized by highly distorted apparent horizon geometries, the metrics quickly evolve, via quasi-normal ringdown, to equilibrium static black hole solutions at late times. The lowest angular number quasi-normal modes are consistent with the linear modes previously found in perturbative studies, whereas the higher angular modes are a combination of linear modes and of harmonics arising from non-linear mode-coupling. We extract the stress energy tensor of the dual CFT on the boundary, and find that despite being highly inhomogeneous initially, it nevertheless evolves from the outset in a manner that is consistent with a thermalized N=4 SYM fluid. As a first step towards closer contact with relativistic heavy ion collision physics, we map this solution to a Minkowski piece of the R{\times}S3 boundary, and obtain a corresponding fluid flow in Minkowski space