Coherent radar reflections from an electron-beam induced particle cascade

Experiment T-576 ran at SLAC in 2018, in development of a new radar-based detection scheme for ultra-high energy neutrinos. In this experiment, the electron beam (N∼109e− at ∼10 GeV) was directed into a plastic target to simulate a 1019 eV neutrino-induced shower in ice. This shower was interrogated with radio frequency (RF) radiation, in an attempt to measure a radar-like reflection from the ionization produced in the target during the particle shower. This technique could be employed to detect the rare interactions of ultra-high-energy neutrinos in dense material, such as polar ice sheets, extending the extant energy range of detected neutrinos up to EeV and beyond. In this proceeding, we detail the experiment and present results from the analysis and the observation of a signal consistent with a radar signal

The Radar Echo Telescope for Neutrinos (RET-N)

We present the Radar Echo Telescope for Neutrinos (RET-N). RET-N focuses on the detection of the cosmic neutrino flux above PeV energies by means of the radar detection technique. This method aims to bridge the energy gap between the diffuse neutrino flux detected by IceCube up to a few PeV and the sought for cosmogenic neutrinos at EeV energies by the in-ice Askaryan detectors, as well as the air-shower radio detectors. The radar echo method is based on the detection the ionization trail in the wake of a high-energy neutrino-induced particle cascade in ice. This technique, recently validated in a beam test (T576 at SLAC) is also the basis for the RET-N pathfinder experiment, RET-CR, which is currently under development. Based on the T-576 results, we show that the radar echo method leads to very promising sensitivities to detect cosmic neutrinos in the PeV-EeV region and above. We present the RET-N project and the results of our sensitivity studies

Simulation and Optimisation for the Radar Echo Telescope for Cosmic Rays

The SLAC T-576 beam test experiment showed the feasibility of the radar detection technique to probe high-energy particle cascades in dense media. Corresponding particle-level simulations indicate that the radar method has very promising sensitivity to probe the > PeV cosmic neutrino flux. As such, it is crucial to demonstrate the in-situ feasibility of the radar echo method, which is the main goal of the current RET-CR experiment. Although the final goal of the Radar Echo Telescope is to detect cosmic neutrinos, we seek a proof of principle using cosmic-ray air showers penetrating the (high-altitude) Antarctic ice sheet. When an UHECR particle cascade propagates into a high-elevation ice sheet, it produces a dense in-ice cascade of charged particles which can reflect incoming radio waves. Using a surface cosmic-ray detector, the energy and direction of the UHECR can be reconstructed, and as such this constitutes a nearly ideal in-situ test beam to provide the proof of principle for the radar echo technique. RET-CR will consist of a transmitter array, receiver antennas and a surface scintillator plate array. Here we present the simulation efforts for RET-CR performed to optimise the surface array layout and triggering system, which affords an estimate of the expected event rate

Investigating signal properties of UHE particles using in-ice radar for the RET experiment

The Radar Echo Telescope (RET) experiment plans to use the radar technique to detect Ultra-High Energy (UHE) cosmic rays and neutrinos in the polar ice sheets. Whenever an UHE particle collides with an ice molecule, it produces a shower of relativistic particles, which leaves behind an ionization trail. Radio waves can be reflected off this trail and be detected in antennas. It is critical to understand such a radar signal's key properties as that will allow us to do vertex, angular and energy reconstruction of the primary UHE particle. We will discuss various simulation methods, which will fundamentally rely on ray tracing, to recreate the radar signal and test our reconstruction methods

Toward High Energy Neutrino Detection with the Radar Echo Telescope for Cosmic Rays (RET-CR)

The Radar Echo Telescope for Cosmic Rays (RET-CR) is a pathfinder experiment for the Radar Echo Telescope for Neutrinos (RET-N), a next-generation in-ice detection experiment for ultra high energy neutrinos. RET-CR will serve as the testbed for the radar echo method to probe high-energy particle cascades in nature, whereby a transmitted radio signal is reflected from the ionization left in its wake. This method, recently validated at SLAC experiment T576, shows promising preliminary sensitivity to neutrino-induced cascades above the energy range of optical detectors like IceCube. RET-CR intends to use an in-nature test beam: the dense, in-ice cascade produced when the air shower of an ultra high energy cosmic ray impacts a high-elevation ice sheet. This in-ice cascade, orders of magnitude more dense than the in-air shower that preceded it, is similar in profile and density to the expected cascade from a neutrino-induced cascade deep in the ice. RET-CR will be triggered using surface scintillator technology and will be used to develop, test, and deploy the hardware, firmware, and software needed for the eventual RET-N. We present the strategy, status, and design sensitivity of RET-CR, and discuss its application to eventual neutrino detection

Application of parabolic equation methods to in-ice radiowave propagation for ultra high energy neutrino detection experiments

Many ultra-high-energy neutrino-detection experiments seek radio wave signals from neutrino interactions deep within the polar ice, and an understanding of in-ice radio wave propagation is therefore of critical importance. The parabolic equation (PE) method for modeling the propagation of radio waves is a suitable intermediate between ray tracing and finite-difference time domain (FDTD) methods in terms of accuracy and computation time. The RET collaboration has developed the first modification of the PE method for use in modeling in-ice radio wave propagation for ultra high energy cosmic ray and neutrino detection experiments. In this proceeding we will detail the motivation for the development of this technique, the process by which it was modified for in-ice use, and showcase the accuracy of its results by comparing to FDTD and ray tracing

Modeling in-ice radio propagation with parabolic equation methods

We investigate the use of parabolic equation (PE) methods for solving radio-wave propagation in polar ice. PE methods provide an approximate solution to Maxwell's equations, in contrast to full-field solutions such as finite-difference-time-domain (FDTD) methods, yet provide a more complete model of propagation than simple geometric ray-tracing (RT) methods that are the current state of the art for simulating in-ice radio detection of neutrino-induced cascades. PE are more computationally efficient than FDTD methods, and more flexible than RT methods, allowing for the inclusion of diffractive effects, and modeling of propagation in regions that cannot be modeled with geometric methods. We present a new PE approximation suited to the in-ice case. We conclude that current ray-tracing methods may be too simplistic in their treatment of ice properties, and their continued use could overestimate experimental sensitivity for in-ice neutrino detection experiments. We discuss the implications for current in-ice Askaryan-type detectors and for the upcoming Radar Echo Telescope; two families of experiments for which these results are most relevant. We suggest that PE methods be investigated further for in-ice radio applications

Health, not weight loss, focused programmes versus conventional weight loss programmes for cardiovascular risk factors:A systematic review and meta-analysis

© 2019 The Authors. Published by BMC. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website:Background: Obesity is a cardiovascular disease risk factor. Conventional weight loss (CWL) programmes focus on weight loss, however 'health, not weight loss, focused' (HNWL) programmes concentrate on improved health and well-being, irrespective of weight loss. What are the differences in CVD risk outcomes between these programmes? Aim: To conduct a systematic review and meta-analysis to compare the effects of HNWL with CWL programmes on cardiovascular disease risk factors. Methods: We searched CENTRAL, MEDLINE, EMBASE, PsycINFO, CINAHL, ASSIA, clinical trial registers, commercial websites and reference lists for randomised controlled trials comparing the two programmes (initially searched up to August 2015 and searched updated to 5 April 2019). We used the Mantel-Haneszel fixed-effect model to pool results. Sub-group and sensitivity analyses that accounted for variations in length of follow-up, enhanced programmes and risk of bias dealt with heterogeneity. Results: Eight randomised controlled trials of 20,242 potential studies were included. Improvements in total cholesterol-HDL ratio (mean difference-0.21 mmol/L, 95% confidence interval [-3.91, 3.50]) and weight loss (-0.28 kg [-2.00, 1.44]) favoured HNWL compared to CWL programmes in the long term (53-104 week follow-up), whereas improvements in systolic (-1.14 mmHg, [-5.84, 3.56]) and diastolic (-0.15 mmHg, [-3.64, 3.34]) blood pressure favoured CWL programmes. These differences did not reach statistical significance. Statistically significant improvements in body satisfaction (-4.30 [-8.32,-0.28]) and restrained eating behaviour (-4.30 [-6.77,-1.83]) favoured HNWL over CWL programmes. Conclusions: We found no long-term significant differences in improved CVD risk factors; however, body satisfaction and restrained eating behaviour improved more with HNWL compared to CWL programmes. Yet firm conclusions cannot be drawn from small studies with high losses to follow-up and data sometimes arising from a single small study.Published versio

Automatic and Deliberate Affective Associations with Sexual Stimuli in Women with Superficial Dyspareunia

Current views suggest that in women with superficial dyspareunia the prospect of penile–vaginal intercourse automatically activates fear-related associations. The automatic activation of negative associations is assumed to interfere with the development of sexual arousal. In turn, this may further aggravate the dyspareunia-related complaints. To assess whether automatic negative associations are involved in this sexual pain disorder, women with superficial dyspareunia (n = 35) and a control group (n = 35) completed a modified pictorial Affective Simon Task (AST). Questioning the role of dysfunctional automatic associations in superficial dyspareunia, the AST indicated that symptomatic women displayed relatively positive rather than negative automatic associations with sexual stimuli. At the self-report level, however, affective associations with sex cues were significantly more negative for women with dyspareunia than for controls. This discrepancy between “reflective” and “reflexive” affective associations with sexual stimuli in women with dyspareunia points to the relevance of conscious appraisal and deliberate rather than automatic processes in the onset and maintenance of dyspareunia

Multi-model seascape genomics identifies distinct environmental drivers of selection among sympatric marine species

Background As global change and anthropogenic pressures continue to increase, conservation and management increasingly needs to consider species’ potential to adapt to novel environmental conditions. Therefore, it is imperative to characterise the main selective forces acting on ecosystems, and how these may influence the evolutionary potential of populations and species. Using a multi-model seascape genomics approach, we compare putative environmental drivers of selection in three sympatric southern African marine invertebrates with contrasting ecology and life histories: Cape urchin (Parechinus angulosus), Common shore crab (Cyclograpsus punctatus), and Granular limpet (Scutellastra granularis). Results Using pooled (Pool-seq), restriction-site associated DNA sequencing (RAD-seq), and seven outlier detection methods, we characterise genomic variation between populations along a strong biogeographical gradient. Of the three species, only S. granularis showed significant isolation-by-distance, and isolation-by-environment driven by sea surface temperatures (SST). In contrast, sea surface salinity (SSS) and range in air temperature correlated more strongly with genomic variation in C. punctatus and P. angulosus. Differences were also found in genomic structuring between the three species, with outlier loci contributing to two clusters in the East and West Coasts for S. granularis and P. angulosus, but not for C. punctatus. Conclusion The findings illustrate distinct evolutionary potential across species, suggesting that species-specific habitat requirements and responses to environmental stresses may be better predictors of evolutionary patterns than the strong environmental gradients within the region. We also found large discrepancies between outlier detection methodologies, and thus offer a novel multi-model approach to identifying the principal environmental selection forces acting on species. Overall, this work highlights how adding a comparative approach to seascape genomics (both with multiple models and species) can elucidate the intricate evolutionary responses of ecosystems to global change