CEP-stable Tunable THz-Emission Originating from Laser-Waveform-Controlled Sub-Cycle Plasma-Electron Bursts

We study THz-emission from a plasma driven by an incommensurate-frequency two-colour laser field. A semi-classical transient electron current model is derived from a fully quantum-mechanical description of the emission process in terms of sub-cycle field-ionization followed by continuum-continuum electron transitions. For the experiment, a CEP-locked laser and a near-degenerate optical parametric amplifier are used to produce two-colour pulses that consist of the fundamental and its near-half frequency. By choosing two incommensurate frequencies, the frequency of the CEP-stable THz-emission can be continuously tuned into the mid-IR range. This measured frequency dependence of the THz-emission is found to be consistent with the semi-classical transient electron current model, similar to the Brunel mechanism of harmonic generation

Sex‑Specific Changes in Physical Performance Following Military Training: A Systematic Review

This is the final version of the article. Available from Springer Verlag via the DOI in this record.Introduction Men and women joining the military undergo the same training, often in mixed-sex platoons. Given the inherent physiological and physical performance differences between men and women, it is reasonable to question whether sex differences exist in the adaptation to military training and, therefore, whether sex-specific training should be employed to optimise training adaptations. Objective To systematically review the literature evaluating changes in the physical performance of men and women following military training. Methods Six database sources were searched in addition to extensive secondary searching. Primary prospective intervention studies (all designs) evaluating physical training interventions in military populations, reporting pre- to post-training changes in physical fitness outcomes for both women and men, were included. Results We screened 3966 unique records. Twenty-nine studies (n = 37 study reports) were included, most of which were conducted in the USA and evaluated initial training for military recruits. Positive changes were more consistently observed in aerobic fitness and muscle strength (whole body and upper body) outcomes than lower body strength, muscle power or muscle endurance outcomes, following physical training. Relative pre- to post-training changes for all outcome measures tended to be greater in women than men although few statistically significant sex by outcome/time interactions were observed. Conclusion Improvements in some, but not all, performance components were observed following a period of military training. Largely, these improvements were not significantly different between sexes. Further prospective research is needed to evaluate sex-specific differences in the response to physical training in controlled conditions to improve military physical training outcomes for both sexes.This work was commissioned through the Defence Human Capability Science and Technology Centre (DHCSTC, Grant number TIN 3.199). DHCSTC had no role in the design, analysis or writing of this article

A non-linear optimal estimation inverse method for radio occultation measurements of temperature, humidity and surface pressure

An optimal estimation inverse method is presented which can be used to retrieve simultaneously vertical profiles of temperature and specific humidity, in addition to surface pressure, from satellite-to-satellite radio occultation observations of the Earth's atmosphere. The method is a non-linear, maximum {\it a posteriori} technique which can accommodate most aspects of the real radio occultation problem and is found to be stable and to converge rapidly in most cases. The optimal estimation inverse method has two distinct advantages over the analytic inverse method in that it accounts for some of the effects of horizontal gradients and is able to retrieve optimally temperature and humidity simultaneously from the observations. It is also able to account for observation noise and other sources of error. Combined, these advantages ensure a realistic retrieval of atmospheric quantities. A complete error analysis emerges naturally from the optimal estimation theory, allowing a full characterisation of the solution. Using this analysis a quality control scheme is implemented which allows anomalous retrieval conditions to be recognised and removed, thus preventing gross retrieval errors. The inverse method presented in this paper has been implemented for bending angle measurements derived from GPS/MET radio occultation observations of the Earth. Preliminary results from simulated data suggest that these observations have the potential to improve NWP model analyses significantly throughout their vertical range.Comment: 18 (jgr journal) pages, 7 figure

Little groups of irreps of O(3), SO(3), and the infinite axial subgroups

Little groups are enumerated for the irreps and their components in any basis of O(3) and SO(3) up to rank 9, and for all irreps of C$_{\infty}$, C$_{\infty h}$, C$_{\infty v}$, D$_{\infty}$ and D$_{\infty h}$. The results are obtained by a new chain criterion, which distinguishes massive (rotationally inequivalent) irrep basis functions and allows for multiple branching paths, and are verified by inspection. These results are relevant to the determination of the symmetry of a material from its linear and nonlinear optical properties and to the choices of order parameters for symmetry breaking in liquid crystals.Comment: 28 pages and 3 figure

What helps to support people affected by Adverse Childhood Experiences? A review of evidence

Adverse Childhood Experiences (ACEs) include physical, sexual or emotional abuse; neglect; domestic violence in the home; homelessness or living in care; parental mental health problems or substance abuse; and parents who are absent through imprisonment, separation or death. We sought to understand how people affected by ACEs can best be supported by conducting a review of evidence. The review involved three components: a qualitative synthesis of UK views studies; a systematic review of reviews which measured the effectiveness of interventions to support people affected by ACEs; and a stakeholder workshop with young people with lived experience of ACEs. The review was commissioned by the Department of Health and Social Care

Precision public health – A critical review of the opportunities and obstacles

The term ‘precision public health’ (PPH) refers to a new approach in public health which involves the use of novel data sources and/or computer science-driven methods of data analysis to predict risk or outcomes, in order to improve how interventions are targeted or tailored, with the aim of making them more individualised and therefore more effective and cost-effective than methods currently in use. These data may include, for example, information from social media or devices, genomic or clinical data, and information from healthcare services. In this critical review, which was conducted between March and October 2019, we outline key assumptions underpinning the PPH approach and identify potential challenges in its application. We adopted a pragmatic, non-systematic review methodology to examine: (i) the general principles underlying PPH; (ii) the validity of claims made about PPH in empirical studies and commentaries; and (iii) the potential opportunities and challenges of adopting a PPH approach through examining two case studies: health checks and community-based interventions. Non-empirical studies (commentaries and think-pieces) were included in this review because PPH represents an emerging approach and many of the ideas around the potential of PPH are only described in such studies Commentary studies emphasise that precision can be achieved in targeting interventions towards narrow social profiles of people through the incorporation of data reflecting micro-level day-to-day insights into the lives of individuals. Structured analysis of commentary studies shows that (i) the PPH field may be highly influenced by commentary and non-systematic review pieces that lack transparent methods but make claims about the potential of PPH; (ii) commentators on PPH often attempt to provide evidence for claims but the link between the evidence and the claim is often unsubstantiated when critically examined; and (iii) many of the assumptions underlying PPH are not supported by empirical evidence suggesting that there needs to be a measured approach to adopting PPH approaches. Claims around the effectiveness of PPH and around PPH being an advance on current public health approaches tended not to be supported by empirical evidence. As a relatively new concept therefore, there is limited direct empirical evidence showing PPH to be effective, and the theoretical arguments in its favour are often not well supported by evidence. The more ambitious claims made for PPH in the literature often rest on questionable readings of the evidence – for example, citing the possibility of identifying subgroups of the population through better targeting as though this automatically promises greater effectiveness among interventions targeting those subgroups. In practice, it seems that PPH is less a radically new paradigm and more a range of incremental improvements to public health interventions. Hypothetical case studies outlining the potential of a PPH approach applied to health checks and community-based interventions indicate several ways in which new data or tools could be productively used to inform the design and implementation of public health interventions. Current evidence suggests the impact of these is likely to be fairly modest, although further focused research (e.g. exploring the utility of strategies for targeting or involving communities using PPH) may merit further exploration and evaluation. Defining PPH is contentious and our findings reflect the difficulty in assessing and operationalising the broad ambition of using emerging data and technologies to better understand profiles, predict risk and outcomes, and act upon this evidence. Future work in this area should seek to introduce more focus around the concept of PPH, including being clearer about the goals and breaking down the concept into a series of components that can each be evaluated. The bulk of the work presented here took place between March and October 2019. There is scope for further analysis to understand the potential of PPH in the future, as the number of studies adopting a PPH approach grows. This larger pool of studies may also lend itself to more systematic approaches to reviewing the evidence, particularly if there is an interest in evaluating a particular component or principle of PPH. In addition, the evidence examined in this report predates the COVID-19 global pandemic, and many of the measures taken to mitigate the spread of the pandemic may provide a further source of evidence and data to understand the potential role of PPH in public health decision-making

Biomechanics of predator–prey arms race in lion, zebra, cheetah and impala

The fastest and most manoeuvrable terrestrial animals are found in savannah habitats, where predators chase and capture running prey. Hunt outcome and success rate are critical to survival, so both predator and prey should evolve to be faster and/or more manoeuvrable. Here we compare locomotor characteristics in two pursuit predator–prey pairs, lion–zebra and cheetah–impala, in their natural savannah habitat in Botswana. We show that although cheetahs and impalas were universally more athletic than lions and zebras in terms of speed, acceleration and turning, within each predator–prey pair, the predators had 20% higher muscle fibre power than prey, 37% greater acceleration and 72% greater deceleration capacity than their prey. We simulated hunt dynamics with these data and showed that hunts at lower speeds enable prey to use their maximum manoeuvring capacity and favour prey survival, and that the predator needs to be more athletic than its prey to sustain a viable success rate