Asteroids and Comets: U.S. and International Law and the Lowest-Probability, Highest Consequence Risk

Asteroids and comets pose unique policy problems. They are the ultimate example of a low probability, high consequence event: no one in recorded human history is confirmed to have ever died from an asteroid or a comet, but the odds are that at some time in the next several centuries (and conceivably next year) an asteroid or a comet will cause mass localized destruction and that at some time in the coming half million years (and conceivably next year), an asteroid or a comet will kill several billion people. The sudden extinction of the dinosaurs, and most other species 65 million years ago, is now generally attributed to the impact of a 10-kilometer-wide comet or asteroid at Chicxulub in Mexico\u27s Yucatan Peninsula that left a 110-mile-wide crater. Even our own century has seen smaller-scale impacts. On June 30, 1908, hundreds of square miles of trees were burned and herds of reindeer may have been incinerated in the Tunguska region of Siberia by an explosion with the force of 1,000 Hiroshima bombs, apparently caused by a 60-meter asteroid. Airborne blasts in the kiloton to megaton range were observed in 1930 at the Curuca River in Brazil; in 1947 at Sikhote-Alin, Siberia; in 1965 over Revelstoke, Canada; and over Ontario in 1966 and Alaska in 1969. Most recently, on November 22, 1996, a meteorite crashed into a coffee field in Honduras, leaving a 165-footwide crater

Mechanisms for Stable Sonoluminescence

A gas bubble trapped in water by an oscillating acoustic field is expected to either shrink or grow on a diffusive timescale, depending on the forcing strength and the bubble size. At high ambient gas concentration this has long been observed in experiments. However, recent sonoluminescence experiments show that in certain circumstances when the ambient gas concentration is low the bubble can be stable for days. This paper presents mechanisms leading to stability which predict parameter dependences in agreement with the sonoluminescence experiments.Comment: 4 pages, 3 figures on request (2 as .ps files

Assessing the invertebrate fauna trajectories in remediation sites of Winstone Aggregates Hunua quarry in Auckland

This study monitored the invertebrates in restoration plantings in the Winstone Aggregates Hunua Quarry. This was to assess the re-establishment of invertebrates in the restoration planting sites and compare them with unplanted control and mature sites. This study follows on from a baseline study carried out in 2014-2015 measuring the restoration trajectory of invertebrates in the Winstone Aggregate Hunua quarry site. A range of entomological monitoring techniques were used and found that dung beetles, millipedes, foliage moths, leaf litter moths and some mite species increased in numbers from the control sites through to the mature sites, while ants, rove beetles, grass moths, some carabid beetles, and worms showed a downwards trend from the mature sites to the control sites. Further monitoring of invertebrates in the restoration area should be carried out

Sonoluminescing air bubbles rectify argon

The dynamics of single bubble sonoluminescence (SBSL) strongly depends on the percentage of inert gas within the bubble. We propose a theory for this dependence, based on a combination of principles from sonochemistry and hydrodynamic stability. The nitrogen and oxygen dissociation and subsequent reaction to water soluble gases implies that strongly forced air bubbles eventually consist of pure argon. Thus it is the partial argon (or any other inert gas) pressure which is relevant for stability. The theory provides quantitative explanations for many aspects of SBSL.Comment: 4 page

The Role of Pressure in Inverse Design for Assembly

Isotropic pairwise interactions that promote the self assembly of complex particle morphologies have been discovered by inverse design strategies derived from the molecular coarse-graining literature. While such approaches provide an avenue to reproduce structural correlations, thermodynamic quantities such as the pressure have typically not been considered in self-assembly applications. In this work, we demonstrate that relative entropy optimization can be used to discover potentials that self-assemble into targeted cluster morphologies with a prescribed pressure when the iterative simulations are performed in the isothermal-isobaric ensemble. By tuning the pressure in the optimization, we generate a family of simple pair potentials that all self-assemble the same structure. Selecting an appropriate simulation ensemble to control the thermodynamic properties of interest is a general design strategy that could also be used to discover interaction potentials that self-assemble structures having, for example, a specified chemical potential.Comment: 29 pages, 8 figure

Asymmetric Fluid Criticality I: Scaling with Pressure Mixing

The thermodynamic behavior of a fluid near a vapor-liquid and, hence, asymmetric critical point is discussed within a general ``complete'' scaling theory incorporating pressure mixing in the nonlinear scaling fields as well as corrections to scaling. This theory allows for a Yang-Yang anomaly in which \mu_{\sigma}^{\prime\prime}(T), the second temperature derivative of the chemical potential along the phase boundary, diverges like the specific heat when T\to T_{\scriptsize c}; it also generates a leading singular term, |t|^{2\beta}, in the coexistence curve diameter, where t\equiv (T-T_{\scriptsize c}) /T_{\scriptsize c}. The behavior of various special loci, such as the critical isochore, the critical isotherm, the k-inflection loci, on which \chi^{(k)}\equiv \chi(\rho,T)/\rho^{k} (with \chi = \rho^{2} k_{\scriptsize B}TK_{T}) and C_{V}^{(k)}\equiv C_{V}(\rho,T)/\rho^{k} are maximal at fixed T, is carefully elucidated. These results are useful for analyzing simulations and experiments, since particular, nonuniversal values of k specify loci that approach the critical density most rapidly and reflect the pressure-mixing coefficient. Concrete illustrations are presented for the hard-core square-well fluid and for the restricted primitive model electrolyte. For comparison, a discussion of the classical (or Landau) theory is presented briefly and various interesting loci are determined explicitly and illustrated quantitatively for a van der Waals fluid.Comment: 21 pages in two-column format including 8 figure

Usefulness of Current Patient-Reported Outcome Scales for ACL Injury: A Mixed-Methods Evaluation of Stakeholder-Perceived Utility of Specific Constructs and Items Across the Rehabilitation Timeline

BACKGROUND: Numerous patient-reported outcome measures (PROMs) have been used in patients with anterior cruciate ligament reconstruction (ACLR), often with overlapping constructs of interest and limited content validity. Inefficient scale application increases burden and diminishes overall usefulness for both the patient and practitioner. PURPOSE: To isolate specific PROM items across a diverse set of constructs that patients and practitioners perceive as having the greatest value at various stages of recovery and return to sport (RTS) in patients after ACLR. STUDY DESIGN: Cross-sectional study. METHODS: A combined 77 stakeholders participated in this 2-phase mixed-methods investigation. In phase 1, a total of 27 patients and 21 practitioners selected individual PROM items from various constructs that had the greatest utility or importance. In phase 2, the highest rated items were further tested in a head-to-head comparison with 29 stakeholders who attended the 2022 ACL Injury Research Retreat. In addition to the utility assessment, practitioners answered other questions related to importance and timing of PROM assessments. RESULTS: In phase 1, both patients and practitioners shared the same top item in 6 of the 8 (75%) constructs assessed. In phase 2, the construct of psychological burden was rated as extremely important by 59% of respondents, followed by physical function (54%), symptoms (35%), and donor site issues (10%). The PROM items of confidence, perceived likelihood of reinjury, and difficulty stopping quickly were rated by a respective 93%, 89%, and 86% of the sample as either very useful or extremely useful. All constructs except donor site issues were rated by most stakeholders to be absolutely necessary to evaluate treatment progress and RTS readiness at the 6-month postoperative time and at RTS. CONCLUSION: Overall, psychological burden, with specific items related to confidence and reinjury likelihood, were rated as most important and useful by both patients and practitioners. The second most important and useful PROM item was related to higher intensity function (eg, decelerating or jumping/landing activities during sports)