Missing energy in black hole production and decay at the Large Hadron Collider

Black holes could be produced at the Large Hadron Collider in TeV-scale gravity scenarios. We discuss missing energy mechanisms in black hole production and decay in large extra-dimensional models. In particular, we examine how graviton emission into the bulk could give the black hole enough recoil to leave the brane. Such a perturbation would cause an abrupt termination in Hawking emission and result in large missing-energy signatures.Comment: addressed reviewer comments and updated reference

British Society of Paediatric Dentistry: a policy document on dental neglect in children

The British Society of Paediatric Dentistry's (BSPD) first policy document on dental neglect was published online in 2009. It proposed a new original definition of dental neglect, discussed the identification of dental neglect and recommended adopting a tiered response, with three stages of intervention according to level of concern. Furthermore, it detailed how the dental team should both contribute to the child protection process and implement wider measures to safeguard and promote children's welfare. Since 2009, these concepts have been widely adopted in the UK and beyond. Furthermore, there have been significant advances in both research and practice. Policy documents produced by the BSPD represent a majority view, based on the consideration of currently available evidence, and are tailored to a UK working environment. Although this updated document's recommendations remain broadly unchanged, this version reflects the professions' progress in understanding dental neglect and minor updates to terminology and, following a consultation process, has been amended to address the needs of two main audiences—dental professionals and nondental health and social care professionals—in order to enhance interdisciplinary working

Absolutely continuous spectrum for multi-type Galton Watson trees

We consider multi-type Galton Watson trees that are close to a tree of finite cone type in distribution. Moreover, we impose that each vertex has at least one forward neighbor. Then, we show that the spectrum of the Laplace operator exhibits almost surely a purely absolutely continuous component which is included in the absolutely continuous spectrum of the tree of finite cone type.Comment: to appear in Annales Henri Poincar\'

A Gravitational Aharonov-Bohm Effect, and its Connection to Parametric Oscillators and Gravitational Radiation

A thought experiment is proposed to demonstrate the existence of a gravitational, vector Aharonov-Bohm effect. A connection is made between the gravitational, vector Aharonov-Bohm effect and the principle of local gauge invariance for nonrelativistic quantum matter interacting with weak gravitational fields. The compensating vector fields that are necessitated by this local gauge principle are shown to be incorporated by the DeWitt minimal coupling rule. The nonrelativistic Hamiltonian for weak, time-independent fields interacting with quantum matter is then extended to time-dependent fields, and applied to problem of the interaction of radiation with macroscopically coherent quantum systems, including the problem of gravitational radiation interacting with superconductors. But first we examine the interaction of EM radiation with superconductors in a parametric oscillator consisting of a superconducting wire placed at the center of a high Q superconducting cavity driven by pump microwaves. We find that the threshold for parametric oscillation for EM microwave generation is much lower for the separated configuration than the unseparated one, which then leads to an observable dynamical Casimir effect. We speculate that a separated parametric oscillator for generating coherent GR microwaves could also be built.Comment: 25 pages, 5 figures, YA80 conference (Chapman University, 2012

Arc-continent collision: The making of an orogen

Peer Reviewe

Evaluating the productivity, environmental sustainability and wider impacts of agroecological compared to conventional farming systems [Evidence project final report]

•Context, aim and objectives: Existing agriculture systems in the UK are effective at producing safe and relatively cheap food, but they are a cause of greenhouse gas emissions, biodiversity loss, and soil degradation. It has been proposed that greater use of agroecological and regenerative farming would lead to more positive effects. The aim of this project was to evaluate the productivity, environmental sustainability and wider impacts of agroecological compared to conventional farming, by addressing three objectives: 1. to undertake an evidence review of regenerative/agroecological farming systems, 2. to assess the risks, barriers and opportunities, and identifying gaps in the knowledge, and 3. to characterise agroecological farming research capability in the UK, explore gaps and priorities, and explore the potential role of a new “living lab” trial network. •The research has been presented in three separate reports (Burgess et al. 2023, Hurley et al. 2023, and Staley et al. 2023), which are attached as appendices. The main results are summarised here. •Method: Objective 1 was addressed using a desk-based rapid evidence review, and the level of confidence in the analysis was determined using the IPBES four-box model (IPBES 2017, 2018). Objective 2 was addressed by in-depth semi-structured interviews with 23 respondents including farmers in late 2022. The interviews were used to explore definitions of agroecological and regenerative farming, barriers to the adoption, and views towards the concept of ‘living labs’. Objective 3 was addressed through an online survey with 22 respondents from 20 organisations in January and February 2023, an online workshop with 34 participants in January 2023, and informed by the findings of work to address Objectives 1 and 2. •Results and discussion: 1.1 Defining and characterising agroecological farming systems. A review of definitions highlighted, in brief, that organic farming places strong restrictions on inputs, agroecological analyses often focus on principles, and regenerative farming typically emphasises the enhancement of soil health and biodiversity at a farm scale. The stakeholder interviews demonstrated that the terms regenerative agriculture and agroecology are employed interchangeably by some, sequentially by others (with regenerative practices seen as steps towards a bigger whole-farm agroecological system), and viewed by some as discrete (who recognise the social justice, economic and political aspects of agroecology). Within these different interpretations, regenerative practices are often assumed to be those that minimise tillage and bare soil, foster plant diversity, and reduce the use of pesticides and synthetic fertilizers. We noted that the impact of organic, agroecological or regenerative systems on greenhouse gas emissions was implicit rather than explicit. We identified 16 agroecological practices that could be used in the UK: crop rotations, conservation agriculture, cover crops, organic crop production, integrated pest management, the integration of livestock to crop systems, the integration of crops to livestock systems, field margin practices, pasture-fed livestock, multi-paddock grazing, organic livestock systems, tree crops, tree-intercropping, multistrata agroforestry and permaculture, silvopasture, and rewilding. 1.2. Impact of agroecological practices at farm-scale Our detailed review (see Burgess et al. 2023) highlighted that the 16 agroecological practices tended to increase soil and biomass carbon and biodiversity at a field- or farm scale relative to a stated baseline. The soil carbon benefits were due to increased crop cover, the introduction of grass into arable systems, reduced cultivation, and/or the addition of soil amendments. The biodiversity benefits were derived from an increased diversity of crops and habitats, introducing plants that attract pollinators, reduced grazing pressure, and/or reduced use of pesticides and herbicides. Gaps in knowledge were highlighted particularly in terms of greenhouse gas emissions and biodiversity. The analysed effect on yields, product values, and input costs varied according to the practice and the baseline comparison. Hence in most cases, a farmer will need to balance trade-offs, perhaps guided by tools such as financial, economic, or life cycle analyses. In some cases, such as organic farming, a reduction in profitability due to a reduction in yield and certification costs may be compensated by an increase in product price. 1.3 Modelling agroecological systems in a UK context Our review highlighted existing modelling frameworks such as ASSET, ERAMMP IMP, EVAST and NEVO that could be repurposed to model agroecological systems across the UK. However we identified three barriers to their successful use. Firstly, modellers need to quantify the links between agroecological scenarios, spatial contexts and selected parameters within the underlying models. Secondly, the lack of readily available experimental data on the effect of agroecological practices and their change over time means that parameterising models remains challenging, and the alternative use of expert-based scoring or benefits transfer approaches can result in very large levels of uncertainty. Thirdly, a validated assessment of the aggregated impact of agroecological practices at a national scale will require effective national monitoring approaches that can assess the level of implementation of agroecological practices. 2. Opportunities from and barriers to a transition to agroecological systems: The uptake of agroecological practices by farm businesses depends on the balance between the opportunities offered and the barriers to implementation. As indicated in 1.2, the opportunities include increased biomass carbon, increased soil carbon in surface layers, and increased on-farm biodiversity. Supermarkets could support environmentally-positive practices, but there is also a strong drive for low food prices. The barriers to some agroecological practices will be geographical or incompatibility with management objectives at the farm-level. However, where these are not constraints, the major barriers are often related to uncertainty in the effect of the practices on yields and costs, and the need to finance the initial investment and certification costs. Enablers to overcome those barriers include knowledge exchange (particularly as the promotion of agroecological practices is not driven by organisations wanting to sell a product) and financial incentives (with a focus on market mechanisms that differentiate between desired and undesired societal outcomes). Evidence from other countries, particularly France, show that agroecological transitions can succeed where the right combination of policy instruments (e.g. grants, support for advice and collaboration, cultural support) are sustained by long-term political will. 3.1 Existing agroecological farming research capability and infrastructure in the UK: The online survey results indicate that most agroecological farming research initiatives and networks were funded by charities, NGOs, or funded by themselves, with some receiving UK or EU government funding. The initiatives ranged from single sites to networks of 50-100 sites, and with agroecological practices applied from one to over 20 years. Farmer participation in such research may be biased to those who can afford the time and money. Five case studies are examined in the main report (Staley et al. 2023) including an ongoing living lab network, three research projects, and a long-term demonstration farm. Only about 60% of respondents were collecting data from their network, often focused on biodiversity. About three-quarters of those not collecting data, would collect data given more funding, knowledge, or support. Face-to-face and email communication was most frequently used between farms in a network. Around two-thirds of respondents held farm demonstration days as a means of knowledge exchange, and further knowledge exchange was a common future aspiration. 3.2 Research gaps and priorities: The survey and workshop supported the observation from 1.2 that many of the impacts of agroecology practices, especially in relation to greenhouse gas emissions and biodiversity, remain poorly understood. Although 1.2 focused on farm-level effects, the consequential effects of, for example, reduced yields with agroecological practices remains a pertinent area for research. The variation in responses between soil types or regions would also be useful to improve the understanding of scaling-up opportunities. The need to support research over a sustained time period was also highlighted as several years are often needed for effects to become apparent. The transition to agroecological farming across different types of business requires the need for farmer support and changes in agricultural education. The role of economic drivers and supply chain structures in supporting agroecological practices also requires more research. Standardisation of data quality and formats, in particular for regulatory data, could help reduce some barriers, but it could also constrain innovation. National assessments of agroecological practices are also constrained by a lack of uptake data. 3.3 Informing a potential UK living labs trial network Living labs have been defined as “user-centred, open innovation ecosystems based on a systematic user co-creation approach, integrating research and innovation processes in real life communities and settings” (Malmberg et al. 2017). Important roles for a living labs network include providing robust locally-relevant evidence of the productivity and financial viability of agroecological farming, improving data standardisation, and encouraging collaboration between farmers, organisations, and researchers for data collection, sharing, and use. The role of Defra in a living labs network should be negotiated carefully with existing stakeholders involved in agroecological/regenerative transitions. Such a network should be sufficiently resourced in order to fund research and knowledge exchange and in order to build capacity among farmers and organisational stakeholders. Building on the response of the survey, case studies, and workshops, the benefits and disadvantages of four options were examined: 1) Develop a standardised methodology or protocol to support consistency of farm measurements. Soil carbon and farm carbon accounting were particularly highlighted. 2) To maximise synergies within existing agroecological farm networks with standardised data collection. 3) A new research network set up to apply agroecological practices on commercial farms, co-designed between farmers and researchers, with standardised data collection on impacts and trade-offs. 4) A long-term living lab UK network set up, with funded facilitation roles and research projects. Some of the above options could be applied in combination. The optimal option will depend on the ambition of Defra and the available funding and timescales

Bell-inequality violation with "thermal" radiation

The model of a quantum-optical device for a conditional preparation of entangled states from input mixed states is presented. It is demonstrated that even thermal or pseudo-thermal radiation can be entangled in such a way, that Bell-inequalities are violated

Reassessing changes in diurnal temperature range: Intercomparison and evaluation of existing global data set estimates

Changes in diurnal temperature range (DTR) over global land areas are compared from a broad range of independent data sets. All data sets agree that global-mean DTR has decreased significantly since 1950, with most of that decrease occurring over 1960–1980. The since-1979 trends are not significant, with inter-data set disagreement even over the sign of global changes. Inter-data set spread becomes greater regionally and in particular at the grid box level. Despite this, there is general agreement that DTR decreased in North America, Europe, and Australia since 1951, with this decrease being partially reversed over Australia and Europe since the early 1980s. There is substantive disagreement between data sets prior to the middle of the twentieth century, particularly over Europe, which precludes making any meaningful conclusions about DTR changes prior to 1950, either globally or regionally. Several variants that undertake a broad range of approaches to postprocessing steps of gridding and interpolation were analyzed for two of the data sets. These choices have a substantial influence in data sparse regions or periods. The potential of further insights is therefore inextricably linked with the efficacy of data rescue and digitization for maximum and minimum temperature series prior to 1950 everywhere and in data sparse regions throughout the period of record. Over North America, station selection and homogeneity assessment is the primary determinant. Over Europe, where the basic station data are similar, the postprocessing choices are dominant. We assess that globally averaged DTR has decreased since the middle twentieth century but that this decrease has not been linear

The Planetary Nebula Luminosity Function at the Dawn of Gaia

The [O III] 5007 Planetary Nebula Luminosity Function (PNLF) is an excellent extragalactic standard candle. In theory, the PNLF method should not work at all, since the luminosities of the brightest planetary nebulae (PNe) should be highly sensitive to the age of their host stellar population. Yet the method appears robust, as it consistently produces < 10% distances to galaxies of all Hubble types, from the earliest ellipticals to the latest-type spirals and irregulars. It is therefore uniquely suited for cross-checking the results of other techniques and finding small offsets between the Population I and Population II distance ladders. We review the calibration of the method and show that the zero points provided by Cepheids and the Tip of the Red Giant Branch are in excellent agreement. We then compare the results of the PNLF with those from Surface Brightness Fluctuation measurements, and show that, although both techniques agree in a relative sense, the latter method yields distances that are ~15% larger than those from the PNLF. We trace this discrepancy back to the calibration galaxies and argue that, due to a small systematic error associated with internal reddening, the true distance scale likely falls between the extremes of the two methods. We also demonstrate how PNLF measurements in the early-type galaxies that have hosted Type Ia supernovae can help calibrate the SN Ia maximum magnitude-rate of decline relation. Finally, we discuss how the results from space missions such as Kepler and Gaia can help our understanding of the PNLF phenomenon and improve our knowledge of the physics of local planetary nebulae.Comment: 12 pages, invited review at the conference "The Fundamental Cosmic Distance Scale: State of the Art and Gaia Perspective", to appear in Astrophysics and Space Scienc