A D-moduli problem?

We point out a generic problem in string-inspired supergravity models with an anomalous $U(1)_X$. A large number of matter multiplets charged under $U(1)_X$ remain massless above the supersymmetry-breaking scale because of degeneracy of vacua solving the D-flatness conditions. A toy model is analyzed as an illustration of the mechanism; we find the surprising result that many scalars remain massless after supersymmetry-breaking in a hidden sector.Comment: 11 pages, full postscript also available from http://phyweb.lbl.gov/theorygroup/papers/44856.p

Developing useful early warning and prognostic scores for COVID-19

Abstract Early recognition of high-risk or deteriorating patients with COVID-19 allows timely treatment escalation and optimises allocation of scarce resources across overstretched healthcare systems. Since the late 1990s, physiological scoring systems have been used in hospital settings to provide an objective signal of clinical deterioration prompting urgent clinical review. Several early warning scores (EWS) accurately predict the need for intensive care unit admission and survival in hospitalised patients with sepsis and other acute illnesses, and their routine use is now recommended in secondary care settings in high and low income countries alike. However, there are widespread concerns that existing EWS, which place a premium on the cardiovascular instability seen in severe sepsis, may fail to identify the deteriorating COVID-19 patient. Dozens of research groups have now assessed the predictive value of existing EWS in hospitalised adults with COVID-19, and used sophisticated statistical methods to develop novel early warning and prognostic scores incorporating vital signs, laboratory tests and imaging results. However, many of these novel scores are at high risk of bias and few have been adopted in routine clinical practice. In this education and learning article, we will discuss key pitfalls of existing prognostic and EWS in hospitalised adults with COVID-19; outline promising novel scores for this patient group; and describe the ideal properties of scoring systems suitable for use in low and middle income settings

“Step by step”: high frequency short-distance epizoochorous dispersal of aquatic macrophytes

Aquatic macrophytes can successfully colonise and re-colonise areas separated by space and time. The mechanisms underlying such “mobility” are not well understood, but it has often been hypothesised that epizoochory (external dispersal) plays an important role. Yet, there is only limited, and mostly anecdotal, evidence concerning successful epizoochorous dispersal of aquatic macrophytes, particularly in the case of short-distance dispersal. Here we examine in situ and ex situ dispersal of aquatic macrophytes, including three invasive alien species. A high frequency of Lemna minor Linnaeus dispersal was observed in situ, and this was linked to bird-mediated epizoochory. We concluded that wind had no effect on dispersal. Similarly, in an ex situ examination Lemna minuta Kunth and Azolla filiculoides Lamarck, were found to be dispersed with a high frequency by mallard ducks (Anas platyrhynchos). No dispersal was measured for Elodea nuttalli (Planchon) H. St. John. It is concluded that short-distance or “stepping-stone” dispersal via bird-mediated epizoochory can occur with high frequencies, and therefore can play an important role in facilitating colonisation, range expansion and biological invasion of macrophytes

Scoping report on the potential impact of on-board desulphurisation on the water quality in SOx emission control areas

The input of acid substances (like SO2) into the sea has been recognized as an environmental issue that needs to be considered in terms of ocean acidification; acid inputs and techniques to deal with them have implications for member states' obligations under the Water Framework Directive and Marine Strategy Framework Directive. This study provides an initial assessment on the potential impact of on-board desulphurisation equipment (open loop scrubbers) on the seawater quality with focus on SOx Emission Control Areas (SECAs). The study focuses on the potential impact of shipborne SO2 on acidification (pH) of seawater in comparison to the impact from climate change. The report comprises a literature study and a dedicated modelling exercise covering the North Sea region. Most available studies and the peer reviewed literature found only a small additional impact from SO2 emissions on acidification in the various investigated parts of the world ocean. However these studies generally assessed spatially averaged effects and regional and coastal oriented studies are mostly lacking from the literature, which means that potential effects to vulnerable ecosystems in such areas have not previously been considered. A coupled hydrodynamic-chemistry model was employed to assess the impact of adding SO2 and CO2 on the complex carbonate system in sea water. The impact on the pH decrease in the open North Sea region from discharging the acid wash water into the seawater was found to be small, but not insignificant, and regionally varying. The calculated annual mean decrease of pH due to SO2 injection for the North Sea total water column is 0.00011; when considering only the change in the surface layer (0-20m), the annual decrease is 0.00024. The total annual impact from increasing atmospheric CO2 concentrations on the acidification of the North Sea surface area is about 8 times stronger (0.001) than the impact from wash water injection. However because of the pronounced spatial variations the mean impact does not reflect the overall situation well. Consequently we find critical regions with high ship traffic intensity, for example along the shipping lanes and in the larger Rotterdam port area. Here, the contribution from SO2 injection can be double the impact from increasing CO2 concentrations and 20 times larger than the North Sea mean value. These critical regions indicate potential problems related to the surface water quality in ports, estuaries and coastal waters that are subject to regulation under the Water Framework Directive (WFD). In addition, the problem of decreasing pH caused by SO2 input from ship exhaust gases in regional seas (North Sea) is relevant to the obligation of the Member States to assess the environmental state of their marine areas and to establish a Good Environmental Status (GES) under the Marine Strategy Framework Directive (MFSD), as pH value is one of the GES criteria

A Model of Direct Gauge Mediation

We present a simple model of gauge mediation (GM) which does not have a messenger sector or gauge singlet fields. The standard model gauge groups couple directly to the sector which breaks supersymmetry dynamically. This is the first phenomenologically viable example of this type in the literature. Despite the direct coupling, the model can preserve perturbative gauge unification. This is achieved by the inverted hierarchy mechanism which generates a large scalar expectation value compared to the size of supersymmetry breaking. There is no dangerous negative contribution to the squark, slepton masses due to two-loop renormalization group equation. The potentially non-universal supergravity contribution to the scalar masses can be suppressed enough to maintain the virtue of the gauge mediation. The model is completely chiral, and one does not need to forbid mass terms for the messenger fields by hand. Beyond the simplicity of the model, it possesses cosmologically desirable features compared to the original models of GM: an improved gravitino and string moduli cosmology. The Polonyi problem is back unlike in the original GM models, but is still much less serious than in hidden sector models.Comment: LaTeX, 12 page

The impact of a training intervention with spatial occlusion goggles on controlling and passing a football

Introduction: The current study analysed the impact of spatial occlusion training on control and pass accuracy in football. Occlusion was achieved using goggles that removed the sight of the lower limbs and football as it was projected towards the participants. Methods: Fifteen skilled male football players were randomly assigned to one of three groups; Occlusion, Practice and Control. Participants were required to control a projected football, before passing it to one of two designated targets, while concurrently identifying a series of randomly generated numbers. Pass direction was determined by a directional arrow that accompanied each number, which coincided with the football release. The study design consisted of a pre-test, training intervention (400 trials), post-test and 2-day retention test. The performance was evaluated via three variables: outcome error, control error and number call error. Results: The results demonstrated a significant decrease in outcome error (p \u3c 0.05) and number call error (p \u3c 0.05) for the Occlusion group from pre-test to post and retention test. No significant decrease was experienced from post-test to retention test (p\u3e 0.05), demonstrating a learning effect. Conclusion: This suggests that reducing visual information during training may have a positive impact on performance once full visual conditions are restored

The impact of a spatial occlusion training intervention on pass accuracy across a continuum of representative experimental design in football

Introduction: The ability to successfully complete a pass in football can positively impact the result of the game. While previous work has identified the importance of perceptual behaviours before and during passing action, there is a paucity of research analysing the impact of training interventions on pass performance. Methods: A tri-phasic approach was employed to assess the impact of training with spatial occlusion goggles. Each phase was designed to assess participants’ ability to control and pass a football during a representative experimental task. The study design consisted of a pre-test, 2-week training intervention, post-test and 2-week retention test. Results: Significant improvements in response accuracy (ppp Conclusion: Findings suggest that guiding the visual system away from the lower limbs while receiving a football and towards relevant information, the movement of a particular participant, within the environment can improve pass accuracy and speed of pass following a training intervention with occlusion goggles

Skill transfer, expertise and talent development: An ecological dynamics perspective

In this paper, we propose an ecological dynamics perspective on expertise and talent development, with a focus on the role of skill transfer. The ecological dynamics theoretical framework provides an integrated explanation for human behaviour in sport, predicated on a conceptualisation including constraints on dynamical systems, ecological psychology and a complex systems approach in neurobiology. Three main pillars are presented, individual-environment coupling as the smallest unit of analysis; adaptation of a complex dynamical system to interacting constraints; and the regulation of action with perception) in order to discuss the functional role of behavioural variability, the usefulness of perceptual-motor exploration and the importance of general and specific skill transfer in the development of talent and expertise in athletes. In addition, practical implications for coaches and instructors are discussed, notably regarding early diversification and unstructured play and activities in talent development programs, but also through variable practice and constraints manipulation

The Impact of Spatial Occlusion Goggles on the Basketball Crossover Dribble

Spatial occlusion involves removing specific sources of visual information such as an object, limb or other information from the visuomotor workspace. In the sports context, limiting an athlete’s visual system to sub-optimal conditions during complex motor skills such as the basketball dribble may be detrimental to performance. However, when normal visual conditions are returned performance may rise above its previous threshold, as athletes then rely less on visual information. In this study, we randomly assigned skilled basketball players into three groups; spatial occlusion (SPO), practice (PRA) and control (CON) and asked participants to execute a basketball crossover dribble task in a motion analysis laboratory. SPO and PRA groups underwent a pre-test, an acquisition phase, a post-test and retention test, while the CON group underwent no acquisition phase. During the acquisition phase, participants in the SPO group wore goggles that occluded vision of the limbs used during the basketball dribble., and the PRA group completed the same acquisition phase without occlusion goggles. Kinematic data during the crossover dribble task revealed a significant SPO group change in the height of the dribble at the third metacarpal (

Cosmological Constraints on Late-time Entropy Production

We investigate cosmological effects concerning the late-time entropy production due to the decay of non-relativistic massive particles. The thermalization process of neutrinos after the entropy production is properly solved by using the Boltzmann equation. If a large entropy production takes place at late time t$\simeq$ 1 sec, it is found that a large fraction of neutrinos cannot be thermalized. This fact loosens the tight constraint on the reheating temperature T_R from the big bang nucleosynthesis and T_R could be as low as 0.5 MeV. The influence on the large scale structure formation and cosmic microwave background anisotropies is also discussed.Comment: 4 pages, using RevTeX and five postscript figures, comments added, to appear in Phys. Rev. Let