Causality in Time-Neutral Cosmologies

Gell-Mann and Hartle (GMH) have recently considered time-neutral cosmological models in which the initial and final conditions are independently specified, and several authors have investigated experimental tests of such models. We point out here that GMH time-neutral models can allow superluminal signalling, in the sense that it can be possible for observers in those cosmologies, by detecting and exploiting regularities in the final state, to construct devices which send and receive signals between space-like separated points. In suitable cosmologies, any single superluminal message can be transmitted with probability arbitrarily close to one by the use of redundant signals. However, the outcome probabilities of quantum measurements generally depend on precisely which past {\it and future} measurements take place. As the transmission of any signal relies on quantum measurements, its transmission probability is similarly context-dependent. As a result, the standard superluminal signalling paradoxes do not apply. Despite their unusual features, the models are internally consistent. These results illustrate an interesting conceptual point. The standard view of Minkowski causality is not an absolutely indispensable part of the mathematical formalism of relativistic quantum theory. It is contingent on the empirical observation that naturally occurring ensembles can be naturally pre-selected but not post-selected.Comment: 5 pages, RevTeX. Published version -- minor typos correcte

Impact of an integrated community-based model of care for older people with complex conditions on hospital emergency presentations and admissions: a step-wedged cluster randomized trial

Background: Health systems must reorient towards preventative and co-ordinated care to reduce hospital demand and achieve positive and fiscally responsible outcomes for older persons with complex needs. Integrated care models can improve outcomes by aligning primary practice with the specialist health and social services required to manage complex needs. This paper describes the impact of a community-facing program that integrates care at the primary-secondary interface on the rate of Emergency Department (ED) presentation and hospital admissions among older people with complex needs. Methods: The Older Persons Enablement and Rehabilitation for Complex Health Conditions (OPEN ARCH) study is a multicentre randomised controlled trial with a stepped wedge cluster design. General practitioners (GPs; n = 14) in primary practice within the Cairns region are considered ‘clusters’ each comprising a mixed number of participants. 80 community-dwelling persons over 70 years of age if non-Indigenous and over 50 years of age if Indigenous were included at baseline with no new participants added during the study. Clusters were randomly assigned to one of three steps that represent the time at which they would commence the OPEN ARCH intervention, and the subsequent intervention duration (3, 6, or 9 months). Each participant was its own control. GPs and participants were not blinded. The primary outcomes were ED presentations and hospital admissions. Data were collected from Queensland Health Casemix data and analysed with multilevel mixed-effects Poisson regression modelling to estimate the effectiveness of the OPEN ARCH intervention. Data were analysed at the cluster and participant levels. Results: Five clusters were randomised to steps 1 and 2, and 4 clusters randomised to step 3. All clusters (n = 14) completed the trial accounting for 80 participants. An effect size of 9% in service use (95% CI) was expected. The OPEN ARCH intervention was found to not make a statistically significant difference to ED presentations or admissions. However, a stabilising of ED presentations and a trend toward lower hospitalisation rates over time was observed. Conclusions: While this study detected no statistically significant change in ED presentations or hospital admissions, a plateauing of ED presentation and admission rates is a clinically significant finding for older persons with complex needs. Multi-sectoral integrated programs of care require an adequate preparation period and sufficient duration of intervention for effectiveness to be measured

Airfoil Tip Leakage Aeroacoustics Predictions using a Lattice Boltzmann Based Method

International audienceThe noise produced by rotating systems such as fans and turbo machines is of growing importance in the academic and engineering communities. The prediction and understanding of the physical mechanisms associated with noise generation are required in order to develop innovative solutions able to efficiently reduce radiated acoustics levels. The flow-induced noise generation mechanisms related to rotating devices are various and complex, and one of them is related to the blade tip flow. The tip flow noise, or tip leakage noise, is particularly important for free-tip configurations, for which the tip flow induced by the pressure gradient between the suction and pressure sides can be particularly intense. The experimental investigation of this mechanism is practically challenging. Consequently, a simplified non-rotating representative configuration has been proposed, and has been previously investigated experimentally. In this paper, transient, compressible, and time-explicit Computational Fluid Dynamics/Computational Aero-Acoustics (CFD/CAA) simulations of an airfoil tip leakage flow for this simplified geometry are performed using a Lattice Boltzmann Method (LBM) based approach. The studied configuration is a NACA 5510 airfoil profile at high Reynolds number flow conditions, for which a variable size gap is introduced between the airfoil and one of the end plates, modeling the tip gap encountered in free-tip fans. First, the simulation results are compared with experimental results to validate the numerical approach. Further investigation of the numerical results underlines the connection between the tip vortex structures and noise radiation, including a parametric study on the Angle of Attack (AoA) and the tip gap width

Genetic cancer risk assessment in general practice: systematic review of tools available, clinician attitudes, and patient outcomes

Background A growing demand for cancer genetic services has led to suggestions for the involvement of GPs. How, and in which conditions, they can be involved, and whether there are important barriers to implementation should be ascertained. Aim To review the tools available, clinician attitudes and experiences, and the effects on patients of genetic cancer risk assessment in general practice. Design and setting Systematic review of papers published worldwide between 1996 and 2017. Method The MEDLINE (via Ovid), EMBASE, Cochrane Library, CINAHL, and PsycINFO databases and grey literature were searched for entries dating from January 1996 to December 2017. Study quality was assessed with relevant Critical Appraisal Skills Programme tool checklists and a narrative synthesis of findings was conducted. Results In total, 40 studies were included in the review. A variety of testing and screening tools were available for genetic cancer risk assessment in general practice, principally for breast, breast–ovarian, and colorectal cancer risk. GPs often reported low knowledge and confidence to engage with genetic cancer risk assessment; however, despite time pressures and concerns about confidentiality and the impact of results on family members, some recognised the potential importance relating to such a development of the GP’s role. Studies found few reported benefits for patients. Concerns about negative impacts on patient anxiety and cancer worries were largely not borne out. Conclusion GPs may have a potential role in identifying patients at risk of hereditary cancer that can be facilitated by family-history tools. There is currently insufficient evidence to support the implementation of population-wide screening for genetic cancer risk, especially given the competing demands of general practice

For wind turbines in complex terrain, the devil is in the detail

Abstract The cost of energy produced by onshore wind turbines is among the lowest available; however, onshore wind turbines are often positioned in a complex terrain, where the wind resources and wind conditions are quite uncertain due to the surrounding topography and/or vegetation. In this study, we use a scale model in a three-dimensional wind-testing chamber to show how minor changes in the terrain can result in significant differences in the flow at turbine height. These differences affect not only the power performance but also the life-time and maintenance costs of wind turbines, and hence, the economy and feasibility of wind turbine projects. We find that the mean wind, wind shear and turbulence level are extremely sensitive to the exact details of the terrain: a small modification of the edge of our scale model, results in a reduction of the estimated annual energy production by at least 50% and an increase in the turbulence level by a factor of five in the worst-case scenario with the most unfavorable wind direction. Wind farm developers should be aware that near escarpments destructive flows can occur and their extent is uncertain thus warranting on-site field measurements.</jats:p

Spontaneous assembly of chemically encoded two-dimensional coacervate droplet arrays by acoustic wave patterning

The spontaneous assembly of chemically encoded, molecularly crowded, water-rich micro-droplets into periodic defect-free two-dimensional arrays is achieved in aqueous media by a combination of an acoustic standing wave pressure field and in situ complex coacervation. Acoustically mediated coalescence of primary droplets generates single-droplet per node micro-arrays that exhibit variable surface-attachment properties, spontaneously uptake dyes, enzymes and particles, and display spatial and time-dependent fluorescence outputs when exposed to a reactant diffusion gradient. In addition, coacervate droplet arrays exhibiting dynamical behaviour and exchange of matter are prepared by inhibiting coalescence to produce acoustically trapped lattices of droplet clusters that display fast and reversible changes in shape and spatial configuration in direct response to modulations in the acoustic frequencies and fields. Our results offer a novel route to the design and construction of ‘water-in-water' micro-droplet arrays with controllable spatial organization, programmable signalling pathways and higher order collective behaviour

Different iron storage strategies among bloom-forming diatoms

Author Posting. © The Author(s), 2018. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America 115(52), (2018): E12275-E12284. doi: 10.1073/pnas.1805243115.Diatoms are prominent eukaryotic phytoplankton despite being limited by the micronutrient iron in vast expanses of the ocean. As iron inputs are often sporadic, diatoms have evolved mechanisms such as the ability to store iron that enable them to bloom when iron is resupplied and then persist when low iron levels are reinstated. Two iron storage mechanisms have been previously described: the protein ferritin and vacuolar storage. To investigate the ecological role of these mechanisms among diatoms, iron addition and removal incubations were conducted using natural phytoplankton communities from varying iron environments. We show that among the predominant diatoms, Pseudo-nitzschia were favored by iron removal and displayed unique ferritin expression consistent with a long-term storage function. Meanwhile, Chaetoceros and Thalassiosira gene expression aligned with vacuolar storage mechanisms. Pseudo-nitzschia also showed exceptionally high iron storage under steady-state high and low iron conditions, as well as following iron resupply to iron-limited cells. We propose that bloom-forming diatoms use different iron storage mechanisms and that ferritin utilization may provide an advantage in areas of prolonged iron limitation with pulsed iron inputs. As iron distributions and availability change, this speculated ferritin-linked advantage may result in shifts in diatom community composition that can alter marine ecosystems and biogeochemical cycles.We thank the captain and crew of the R/V Melville and the CCGS J. P. Tully as well as the participants of the IRNBRU (MV1405) cruise for the California-based data, particularly K. Ellis [University of North Carolina (UNC)], T. Coale (University of California, San Diego), F. Kuzminov (Rutgers), H. McNair [University of California, Santa Barbara (UCSB)], and J. Jones (UCSB). W. Burns (UNC), S. Haines (UNC), and S. Bargu (Louisiana State University) assisted with sample processing and analysis. This work was funded by the National Science Foundation Grants OCE-1334935 (to A.M.), OCE-1334632 (to B.S.T.), OCE-1333929 (to K.T.), OCE-1334387 (to M.A.B.), OCE-1259776 (to K.W.B), and DGE-1650116 (Graduate Research Fellowship to R.H.L).2019-06-1

Density inhomogeneities in heavy ion collisions around the critical point

We study the hydrodynamical expansion of a hot and baryon-dense quark fluid coupled to classical real-time evolution of the long wavelength modes of the chiral field. Significant density inhomogeneities develop dynamically when the transition to the symmetry-broken state occurs. We find that the amplitude of the density inhomogeneities is larger for expansion trajectories crossing the line of first-order transitions than for crossovers, which could provide some information on the location of a critical point. A few possible experimental signatures for inhomogeneous decoupling surfaces are mentioned briefly.Comment: 6 pages, 4 figures, accepted for publication in PL

Impoundment increases methane emissions in Phragmites‐invaded coastal wetlands

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Sanders‐DeMott, R., Eagle, M., Kroeger, K., Wang, F., Brooks, T., Suttles, J., Nick, S., Mann, A., & Tang, J. Impoundment increases methane emissions in Phragmites‐invaded coastal wetlands. Global Change Biology, 28(15), (2022): 4539– 4557. https://doi.org/10.1111/gcb.16217.Saline tidal wetlands are important sites of carbon sequestration and produce negligible methane (CH4) emissions due to regular inundation with sulfate-rich seawater. Yet, widespread management of coastal hydrology has restricted tidal exchange in vast areas of coastal wetlands. These ecosystems often undergo impoundment and freshening, which in turn cause vegetation shifts like invasion by Phragmites, that affect ecosystem carbon balance. Understanding controls and scaling of carbon exchange in these understudied ecosystems is critical for informing climate consequences of blue carbon restoration and/or management interventions. Here, we (1) examine how carbon fluxes vary across a salinity gradient (4–25 psu) in impounded and natural, tidally unrestricted Phragmites wetlands using static chambers and (2) probe drivers of carbon fluxes within an impounded coastal wetland using eddy covariance at the Herring River in Wellfleet, MA, United States. Freshening across the salinity gradient led to a 50-fold increase in CH4 emissions, but effects on carbon dioxide (CO2) were less pronounced with uptake generally enhanced in the fresher, impounded sites. The impounded wetland experienced little variation in water-table depth or salinity during the growing season and was a strong CO2 sink of −352 g CO2-C m−2 year−1 offset by CH4 emission of 11.4 g CH4-C m−2 year−1. Growing season CH4 flux was driven primarily by temperature. Methane flux exhibited a diurnal cycle with a night-time minimum that was not reflected in opaque chamber measurements. Therefore, we suggest accounting for the diurnal cycle of CH4 in Phragmites, for example by applying a scaling factor developed here of ~0.6 to mid-day chamber measurements. Taken together, these results suggest that although freshened, impounded wetlands can be strong carbon sinks, enhanced CH4 emission with freshening reduces net radiative balance. Restoration of tidal flow to impounded ecosystems could limit CH4 production and enhance their climate regulating benefits.This project was supported by USGS-NPS Natural Resources Preservation Program #2021-07, U.S. Geological Survey Coastal & Marine Hazards and Resources Program and the USGS Land Change Science Program's LandCarbon program, and NOAA National Estuarine Research Reserve Science Collaborative NA14NOS4190145. R Sanders-DeMott was supported by a USGS Mendenhall Fellowship and partnership with Restore America's Estuaries