Nostalgia and heritage in Korsten, Port Elizabeth, 1956 to 1990

This study centres on interdisciplinary notions of 'place’ (and its structures), the attachment to place, their ordinary and everyday potential heritage resources and the value of nostalgia as a method for engaging with these marginal heritages. The case is a set of values of a group of past users of a series of entertainment structures in Korsten, Port Elizabeth, from 1956 to 1990. Their everyday experience of living in Korsten, together with the trauma of displacement (as a consequence of forced removals) and the nostalgia associated with the joy of an 'era of entertainment’ they experienced as young adults in new structures such as grand cinemas and dance halls, is central to addressing the argument of this study. Three themes were explored through interviews with eight people. These were: the user experience, responses to nostalgia and the nature of the potential heritage resource. The interviews were initiated by open-ended questions that allowed for diversion and storytelling

Signal recognition particle binds to translating ribosomes before emergence of a signal anchor sequence.

The bacterial signal recognition particle (SRP) is part of the machinery that targets ribosomes synthesizing membrane proteins to membrane-embedded translocons co-translationally. Recognition of nascent membrane proteins occurs by virtue of a hydrophobic signal-anchor sequence (SAS) contained in the nascent chain, usually at the N terminus. Here we use fluorescence-based stopped-flow to monitor SRP-ribosome interactions with actively translating ribosomes while an SRP substrate is synthesized and emerges from the peptide exit tunnel. The kinetic analysis reveals that, at cellular concentrations of ribosomes and SRP, SRP rapidly binds to translating ribosomes prior to the emergence of an SAS and forms an initial complex that rapidly rearranges to a more stable engaged complex. When the growing peptide reaches a length of ∼50 amino acids and the SAS is partially exposed, SRP undergoes another conformational change which further stabilizes the complex and initiates targeting of the translating ribosome to the translocon. These results provide a reconciled view on the timing of high-affinity targeting complex formation, while emphasizing the existence of preceding SRP recruitment steps under conditions of ongoing translation

An entropy stable discontinuous Galerkin method for the shallow water equations on curvilinear meshes with wet/dry fronts accelerated by GPUs

We extend the entropy stable high order nodal discontinuous Galerkin spectral element approximation for the non-linear two dimensional shallow water equations presented by Wintermeyer et al. [N. Wintermeyer, A. R. Winters, G. J. Gassner, and D. A. Kopriva. An entropy stable nodal discontinuous Galerkin method for the two dimensional shallow water equations on unstructured curvilinear meshes with discontinuous bathymetry. Journal of Computational Physics, 340:200-242, 2017] with a shock capturing technique and a positivity preservation capability to handle dry areas. The scheme preserves the entropy inequality, is well-balanced and works on unstructured, possibly curved, quadrilateral meshes. For the shock capturing, we introduce an artificial viscosity to the equations and prove that the numerical scheme remains entropy stable. We add a positivity preserving limiter to guarantee non-negative water heights as long as the mean water height is non-negative. We prove that non-negative mean water heights are guaranteed under a certain additional time step restriction for the entropy stable numerical interface flux. We implement the method on GPU architectures using the abstract language OCCA, a unified approach to multi-threading languages. We show that the entropy stable scheme is well suited to GPUs as the necessary extra calculations do not negatively impact the runtime up to reasonably high polynomial degrees (around $N=7$). We provide numerical examples that challenge the shock capturing and positivity properties of our scheme to verify our theoretical findings

An Entropy Stable Nodal Discontinuous Galerkin Method for the Two Dimensional Shallow Water Equations on Unstructured Curvilinear Meshes with Discontinuous Bathymetry

We design an arbitrary high-order accurate nodal discontinuous Galerkin spectral element approximation for the nonlinear two dimensional shallow water equations with non-constant, possibly discontinuous, bathymetry on unstructured, possibly curved, quadrilateral meshes. The scheme is derived from an equivalent flux differencing formulation of the split form of the equations. We prove that this discretisation exactly preserves the local mass and momentum. Furthermore, combined with a special numerical interface flux function, the method exactly preserves the mathematical entropy, which is the total energy for the shallow water equations. By adding a specific form of interface dissipation to the baseline entropy conserving scheme we create a provably entropy stable scheme. That is, the numerical scheme discretely satisfies the second law of thermodynamics. Finally, with a particular discretisation of the bathymetry source term we prove that the numerical approximation is well-balanced. We provide numerical examples that verify the theoretical findings and furthermore provide an application of the scheme for a partial break of a curved dam test problem

Human Frailty, Unbreakable Victims and Asylum

This article analyzes the asylum decisions of immigration agencies and federal appellate courts and demonstrates that the case law driven standard for persecution is out of step with the original meaning of the term, international law standards, and contemporary understanding of how human beings experience physical and mental harm. Medical and psychological evidence establishes that even trauma at the lower end of the spectrum of severity can inflict lasting and debilitating effects on people\u27s health. Yet over the last three decades, virtually no court decisions have decreased the showing of harm needed to establish persecution. To the contrary, courts have generally ratcheted up what is required. Today, most judicial decisions rest on the unwarranted assumption of an unbreakable asylum applicant who must show systematic and escalating physical mistreatment over a sustained period or a single instance of extraordinary harm that results in a scar, disability, or other lasting physical injury. Although mental harm can qualify as persecution, courts rarely find persecution based solely on mental mistreatment. And courts routinely fail to consider the longstanding mental effects of physical trauma. Court decisions on persecution are consistent with troubling studies suggesting people have difficulty empathizing with, and understanding, the situations of others when there is a lack of immediacy, and that decision makers and authority figures are prone to making racialized attributions of pain on the baseless assumption that people of color can withstand more pain than white people. Decision makers should seek to minimize the tendency to downplay the pain of others in asylum adjudications and adopt a human rights approach, which tags the concept of persecution to the violation of a human right and better tracks the prevailing understanding of how humans experience both physical and mental mistreatment, which grows more encompassing over time

Development of acoustically lined ejector technology for multitube jet noise suppressor nozzles by model and engine tests over a wide range of jet pressure ratios and temperatures

An experimental program comprising model nozzle and full-scale engine tests was undertaken to acquire parametric data for acoustically lined ejectors applied to primary jet noise suppression. Ejector lining design technology and acoustical scaling of lined ejector configurations were the major objectives. Ground static tests were run with a J-75 turbojet engine fitted with a 37-tube, area ratio 3.3 suppressor nozzle and two lengths of ejector shroud (L/D = 1 and 2). Seven ejector lining configurations were tested over the engine pressure ratio range of 1.40 to 2.40 with corresponding jet velocities between 305 and 610 M/sec. One-fourth scale model nozzles were tested over a pressure ratio range of 1.40 to 4.0 with jet total temperatures between ambient and 1088 K. Scaling of multielement nozzle ejector configurations was also studied using a single element of the nozzle array with identical ejector lengths and lining materials. Acoustic far field and near field data together with nozzle thrust performance and jet aerodynamic flow profiles are presented