Degeneracy between mass and spin in black-hole-binary waveforms

We explore the degeneracy between mass and spin in gravitational waveforms emitted by black-hole binary coalescences. We focus on spin-aligned waveforms and obtain our results using phenomenological models that were tuned to numerical-relativity simulations. A degeneracy is known for low-mass binaries (particularly neutron-star binaries), where gravitational-wave detectors are sensitive to only the inspiral phase, and the waveform can be modelled by post-Newtonian theory. Here, we consider black-hole binaries, where detectors will also be sensitive to the merger and ringdown, and demonstrate that the degeneracy persists across a broad mass range. At low masses, the degeneracy is between mass ratio and total spin, with chirp mass accurately determined. At higher masses, the degeneracy persists but is not so clearly characterised by constant chirp mass as the merger and ringdown become more significant. We consider the importance of this degeneracy both for performing searches (including searches where only non-spinning templates are used) and in parameter extraction from observed systems. We compare observational capabilities between the early (~2015) and final (2018 onwards) versions of the Advanced LIGO detector.Comment: 11 pages, 9 figure

Impact of the Equation of State in Core-Collapse Supernovae

One of the key ingredients to the core collapse supernova mechanism is the physics of matter at or near nuclear density. Included in simulations as part of the Equation of State (EoS), nuclear repulsion experienced at high densities is responsible for the bounce shock, which initially causes the outer envelope of the supernova to expand, as well as determining the structure of the newly formed proto-neutron star. Recent years have seen renewed interest in this fundamental piece of supernova physics, resulting in several promising candidate EoS parameterizations. We will present the impact of several of their variations in the nuclear EoS using spherically symmetric, General Relativistic multi group Boltzmann neutrino transport simulations of stellar core bounce and shock propagation

Essay – Finding the Error in Daubert

The Supreme Court in Daubert v. Merrell Dow Pharmaceuticals, Inc. laid down the standard for admissibility of expert testimony. We believe the best standard is simpler than the one chosen by the Court: The Daubert standard really is about discerning the trustworthiness of expert, and trustworthiness is best determined through an expert’s accounting of the error within his testimony. Lower courts have struggled with the Daubert standard. We offer evidence of the problem and propose a new standard that would capture the essence of Daubert but significantly simplify its application

Towards a verified mechanistic model of plankton population dynamics

Plankton are a signicant component of the biogeochemical cycles that impact on the global climate. Plankton ecosystems constitute around 40 % of the annual global primary productivity, and the sinking of plankton to the deep ocean (the so-called biological pump) is the largest permanent loss of carbon from the coupled atmosphere-surface ocean-land system. The biological pump need only increase by 25 % to cancel the anthropogenically-released ux of CO2 into the atmosphere. Mechanistic models of atmosphere-ocean dynamics have proved to have superior predictive capabilities on climate phenomena, such as the El Ni~no, than empirical models. Mechanistic models are based on fundamental laws describing the underlying processes controlling a particular system. Existing plankton population models are primarily empirical, raising doubts to their ability to forecast the behaviour of the plankton system, especially in an altered global climate. This thesis works towards a mechanistic model of plankton population dynamics based primarily on physical laws, and using laboratory-determined parameters. The processes modelled include: diusion and convection to the cell surface, light capture by photosynthetic pigments, sinking and encounter rates of predators and prey. The growth of phytoplankton cells is modelled by analogy to chemical kinetics. The equations describing each process are veried by comparison to existing laboratory experiments. Process-based model verication is proposed as a superior diagnostic tool for model validation than verication based on the changing state of the system over time. To increase our ability to undertake process-based verication, a model of stable isotope fractionation during phytoplankton growth is developed and tested. The developed model has been written to complement other process-based models of biogeochemical cycles. A suite of process-based, biogeochemical models, coupled to an atmosphere-ocean circulation model, will have superior predictive capabilities compared with present global climate models

Ergonomic redesign using quality improvement for pre-hospital care of acute myocardial infarction

Context: Frontline emergency ambulance clinicians collaborated in a national quality improvement (QI) initiative to improve pre-hospital care for patients with acute myocardial infarction (AMI). Problem: The National Ambulance Clinical Performance Indicator (CPI) care bundle for AMI (consisting of aspirin, GTN, pain assessment and administration of analgesia) highlighted a consistent shortfall in patient pain assessment and inadequate provision of analgesia. Ineffective pain management in AMI has negative physiological and psychological effects that can be detrimental to patient outcomes. The aim is to increase the delivery of the entire AMI care bundle to 90% by March 2012 Assessment of problem and analysis of its causes: We explored barriers to effective pain management using process maps, cause-and-effect diagrams and thematic analysis of audio recordings from QI collaborative workshops and semi-structured interviews. We found that ergonomic factors (interaction between human and system factors), which included ineffective and inefficient pain assessment methods, ineffective feedback processes and poor access to analgesia were root causes for suboptimal pain management in AMI. Intervention: Through collaboration with frontline ambulance clinicians, solutions were found to overcome these root causes. These included: •Provider prompts (e.g. aide memoires and checklists) to prompt care bundle delivery. •Modified pain assessment tools (integrating Wong-baker faces, numerical verbal scores from 0 to 10 and descriptive intensity scales). •Individual clinical feedback by a clinical leader. •The introduction of small nitrous oxide canisters to increase availability and administration of analgesia earlier in the care pathway. Strategy for change: We used Plan-Do-Study-Act (PDSA) cycles to improve processes of care in AMI. Once improvements developed through PDSA cycles were identified, these were spread to county divisions and then trust-wide. Results were shared through QI workshops, face-to-face dialogue, e-forums, bulletins, newsletters and magazines locally and nationally. Measurement of improvement: Statistical Process Control (SPC) control methods were used to evaluate the effects of changes implemented. Improvements in the delivery of analgesia and the entire care bundle were achieved through initial awareness raising and implementation of system changes; e.g. provider prompts and revised pain assessment tool etc. We have already seen improvements in performance in the delivery of analgesia and also the care bundle as a whole. Effects of changes: An increase in pain assessment and the delivery of analgesia for patients experiencing AMI will help improve patient outcomes. The preliminary results of this study show improvement in the pain management in AMI. The sustainability of improvements recognised so far, and any variations that may occur as a consequence of subsequent interventions, continue to be monitored. Lessons learnt: A deeper understanding of the current system of care has been achieved by adopting a collaborative approach using QI methods focusing on ergonomics. Greater efforts earlier in the project to nurture a culture for improvement and to foster ownership and support from senior executives could have been an additional facilitator for these activities. Message for others: Systems of care can be ergonomically designed using QI methods to foster an environment that minimises opportunities for mistakes, accidental slips, lapses as well as routine (i.e. purposeful) and exceptional (i.e. unavoidable) violations in pre-hospital pain management

Effects of Defects on Armatures within Helical Flux-Compression Generators

Tubes of aluminum and copper filled with C-4 high-explosive were tested during this study of the effects of explosive flaws and voids, their sizes and locations, and of the effects of armature machining tolerances on the expansion characteristics of armatures within helical flux-compression generators. Flaws and voids were introduced into the explosive fill of 6061-T6 aluminum armatures during assembly. The defects were located along the major axis of the fill, midway between the major axis and the explosive/armature interface, and at the interface. The resulting effects on armature expansion were recorded by high-speed framing camera, intensified charge-coupled display (ICCD) photography and by flash X-ray. Outer and inner surface defects were introduced into OFHC copper and 6061-T6 aluminum armatures via machining. The resulting effects during armature expansion were recorded by framing camera and by ICCD