Experimental Observation of Proton Bunch Modulation in a Plasma at Varying Plasma Densities.

We give direct experimental evidence for the observation of the full transverse self-modulation of a long, relativistic proton bunch propagating through a dense plasma. The bunch exits the plasma with a periodic density modulation resulting from radial wakefield effects. We show that the modulation is seeded by a relativistic ionization front created using an intense laser pulse copropagating with the proton bunch. The modulation extends over the length of the proton bunch following the seed point. By varying the plasma density over one order of magnitude, we show that the modulation frequency scales with the expected dependence on the plasma density, i.e., it is equal to the plasma frequency, as expected from theory.

Experimental Observation of Plasma Wakefield Growth Driven by the Seeded Self-Modulation of a Proton Bunch.

We measure the effects of transverse wakefields driven by a relativistic proton bunch in plasma with densities of 2.1×10^{14} and 7.7×10^{14} electrons/cm^{3}. We show that these wakefields periodically defocus the proton bunch itself, consistently with the development of the seeded self-modulation process. We show that the defocusing increases both along the bunch and along the plasma by using time resolved and time-integrated measurements of the proton bunch transverse distribution. We evaluate the transverse wakefield amplitudes and show that they exceed their seed value (<15 MV/m) and reach over 300 MV/m. All these results confirm the development of the seeded self-modulation process, a necessary condition for external injection of low energy and acceleration of electrons to multi-GeV energy levels.

'Loneliness in the city': examining socio-economics, loneliness and poor health in the North East of England.

OBJECTIVES: The aim of this study was to discover whether lower socio-economic status is associated with increased experiences of loneliness and isolation. The research subsequently determined whether this relationship impacted health inequalities. STUDY DESIGN: The study used a cross-sectional, self-reported survey collecting information on loneliness, isolation and poor health (n = 680). The survey was administered through Sunderland District Council in 2016-2017, and data were analysed at The University of Sunderland. METHODS: The study used a quantitative approach, and data were analysed using descriptive statistics, engaging in univariate, bivariate and multivariate levels of analysis. RESULTS: A number of significant findings emerged from the data analysis, linking lower socio-economic status to experiences of loneliness (P = 0.000) and social isolation (P = 0.000). When determining if social isolation and socio-economics had a detrimental impact on a person's health, no statistical association was discovered (P = 0.098). Yet, there was a significant relationship concerning socio-economic status, loneliness and poor health (P = 0.026). CONCLUSIONS: The authors have identified a number of associations within the data with reference to isolation, loneliness and poor health. Therefore, participants from a lower socio-economic group experienced disproportionately high levels of social isolation and emotional loneliness when compared with other socio-economic groups. The data also demonstrate that participants who experienced loneliness, and who were from a lower socio-economic background, were consistently more likely to report poor health than those from other socio-economic backgrounds.

Acceleration of electrons in the plasma wakefield of a proton bunch.

High-energy particle accelerators have been crucial in providing a deeper understanding of fundamental particles and the forces that govern their interactions. To increase the energy of the particles or to reduce the size of the accelerator, new acceleration schemes need to be developed. Plasma wakefield acceleration1-5, in which the electrons in a plasma are excited, leading to strong electric fields (so called 'wakefields'), is one such promising acceleration technique. Experiments have shown that an intense laser pulse6-9 or electron bunch10,11 traversing a plasma can drive electric fields of tens of gigavolts per metre and above-well beyond those achieved in conventional radio-frequency accelerators (about 0.1 gigavolt per metre). However, the low stored energy of laser pulses and electron bunches means that multiple acceleration stages are needed to reach very high particle energies5,12. The use of proton bunches is compelling because they have the potential to drive wakefields and to accelerate electrons to high energy in a single acceleration stage13. Long, thin proton bunches can be used because they undergo a process called self-modulation14-16, a particle-plasma interaction that splits the bunch longitudinally into a series of high-density microbunches, which then act resonantly to create large wakefields. The Advanced Wakefield (AWAKE) experiment at CERN17-19 uses high-intensity proton bunches-in which each proton has an energy of 400 gigaelectronvolts, resulting in a total bunch energy of 19 kilojoules-to drive a wakefield in a ten-metre-long plasma. Electron bunches are then injected into this wakefield. Here we present measurements of electrons accelerated up to two gigaelectronvolts at the AWAKE experiment, in a demonstration of proton-driven plasma wakefield acceleration. Measurements were conducted under various plasma conditions and the acceleration was found to be consistent and reliable. The potential for this scheme to produce very high-energy electron bunches in a single accelerating stage20 means that our results are an important step towards the development of future high-energy particle accelerators21,22.

Spatial variations in airborne microorganism and endotoxin concentrations at green waste composting facilities.

The emission and dispersal of bioaerosols from open-air commercial composting facilities continues to be contentious. A meta-dataset enumerating cultivable microorganism emission and downwind concentrations is not yet available. A dataset derived from repeated and replicated field studies over a period of two years at two commercial composting facilities is presented. The data characterises patterns in Aspergillus fumigatus, actinomycetes, Gram-negative bacteria and endotoxin emission and downwind concentrations. For all bioaerosols, compost agitation activities had a significant impact on concentrations; levels were variable up to 600 m downwind from site. Bioaerosols declined rapidly from source and exhibited a secondary peak 100-150 m from site boundary. All bioaerosols were found downwind from site in elevated concentrations. Compared to those found 100 m upwind, levels were significantly higher at 180 m downwind for A. fumigatus; at 300-400 m for actinomycetes and Gram negative bacteria, and at 100 m for endotoxins. Periodically, elevated concentrations could be found for all bioaerosols at distances further downwind. The evidence provided by this data set provides operators and regulators of facilities with reliable data to inform the location, risk assessment and bioaerosol sampling strategies of commercial composting facilities.

Rosiglitazone taken once daily provides effective glycaemic control in patients with Type 2 diabetes mellitus.

AIMS: To evaluate the clinical efficacy and safety of rosiglitazone as a once daily treatment for Type 2 diabetes mellitus (DM). METHODS: Three hundred and sixty-nine patients with Type 2 DM (mean age 63 years; mean body mass index (BMI) 29.4 kg/m2) were enrolled in a double-blind, parallel group, placebo-controlled, dose-ranging study. Patients were randomly assigned to receive placebo or rosiglitazone at doses of 4, 8, or 12 mg daily for 8 weeks. RESULTS: At 8 weeks, fasting plasma glucose (FPG) decreased significantly in the rosiglitazone 4 mg, 8 mg, and 12 mg groups (-0.9, -2.0 and -1.7 mmol/l; P = 0.0003, < 0.0001, and < 0.0001, respectively) compared with placebo (+0.4 mmol/l). The improvements in FPG were dose ordered for 4 and 8 mg/ day. The 12 mg/day dose produced no additional improvement. There were small decreases in haemoglobin and haematocrit in the rosiglitazone treatment groups. The overall incidence of adverse experiences was similar in all treatment groups, including placebo with no evidence of hypoglycaemia or hepatotoxicity. CONCLUSIONS: Rosiglitazone improves glycaemic control when given once daily to treat Type 2 diabetes mellitus and is well tolerated at doses up to and including 12 mg.