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Laser-wakefield accelerators (LWFAs) are high acceleration-gradient plasma-based particle accelerators capable of producing ultra-relativistic electron beams. Within the strong focusing fields of the wakefield, accelerated electrons undergo betatron oscillations, emitting a bright pulse of X-rays with a micrometer-scale source size that may be used for imaging applications. Non-destructive X-ray phase contrast imaging and tomography of heterogeneous materials can provide insight into their processing, structure, and performance. To demonstrate the imaging capability of X-rays from an LWFA we have examined an irregular eutectic in the aluminum-silicon (Al-Si) system. The lamellar spacing of the Al-Si eutectic microstructure is on the order of a few micrometers, thus requiring high spatial resolution. We present comparisons between the sharpness and spatial resolution in phase contrast images of this eutectic alloy obtained v ia X-ray phase contrast imaging at the Swiss Light Source (SLS) synchrotron and X-ray projection microscopy via an LWFA source. An upper bound on the resolving power of 2.7 ± 0.3  μ m of the LWFA source in this experiment was measured. These results indicate that betatron X-rays from laser wakefield acceleration can provide an alternative to conventional synchrotron sources for high resolution imaging of eutectics and, more broadly, complex microstructures.

Laser wakefield accelerators commonly produce on-axis, low-divergence, high-energy electron beams. However, a high charge, annular shaped beam can be trapped outside the bubble and accelerated to high energies. Here we present a parametric study on the production of low-energy-spread, ultra-relativistic electron ring beams in a two-stage gas cell. Ring-shaped beams with energies higher than 750 MeV are observed simultaneously with on axis, continuously injected electrons. Often multiple ring shaped beams with different energies are produced and parametric studies to control the generation and properties of these structures were conducted. Particle tracking and particle-in-cell simulations are used to determine properties of these beams and investigate how they are formed and trapped outside the bubble by the wake produced by on-axis injected electrons. These unusual femtosecond duration, high-charge, high-energy, ring electron beams may find use in beam driven plasma wakefield accelerators and radiation sources.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.An amendment to this paper has been published and can be accessed via a link at the top of the paper.

In 1998, the U.S. poultry industry generated almost 12 million Mg of broiler (Gallus gallus domesticus) litter, most of which was applied to grasslands as fertilizer. This litter contains appreciable concentrations of estradiol and testosterone, sex hormones of environmental concern. We measured estradiol and testosterone concentrations in soil and runoff water from large (0.8 ha) grazed and ungrazed grasslands amended with broiler litter. Samples were analyzed by enzyme immunoassay. In runoff, background concentrations were 50 to 150 ng estradiol L−1 and 15 to 125 ng testosterone L−1. No significant differences were observed in runoff concentrations between hayed and grazed plots (p = 0.1). Therefore, grazing animals did not contribute hormones to runoff. When litter was applied, runoff concentrations were 20 to 2530 ng estradiol L−1 and 10 to 1830 ng testosterone L−1, depending on litter application rate and time between application and runoff. In soil, the background concentration for estradiol was 55 ng kg−1. Depending on litter application rate and time from application, the estradiol concentration in soil increased up to 675 ng kg−1. Testosterone followed a similar trend; however, concentrations of testosterone were significantly higher in grazed than in hayed plots (p = 0.1). These results show sizable edge‐of‐field losses of estradiol and testosterone from broiler litter‐amended grasslands, and are the first studies to measure estradiol and testosterone in soil. Future research needs to examine the persistence and degradation of estradiol and testosterone in broiler litter, soil, and runoff.

It is widely recommended that infant boys with undescended testes (UDT) should be referred for surgical opinion before the age of 18 months. To attempt to identify the reasons why the mean age at orchidopexy in our institution was as high as 5.5 years, a retrospective review of the screening history, examinations, and management of boys over the age of 3 years at the time of orchidopexy was undertaken by reference to community, general practitioner, and hospital records. In 36 children where hospital and community records giving information prior to referral were available, the UDT had previously been documented on at least one occasion as descended in 24 children or retractile in 10. In 1 child there was delayed referral, and in another, there was operative delay. It is concluded that there is either frequent failure of the Child Health Surveillance screening programme, or that late ascent of a testis previously sited in the scrotum is a common occurrence. We recommend further prospective studies to clarify this latter phenomenon.

Strontium-89 and samarium-153 are radioisotopes that are approved in the USA and Europe for the palliation of pain from metastatic bone cancer, whereas rhenium-186 and rhenium-188 are investigational. Radioisotopes are effective in providing pain relief with response rates of between 40% and 95%. Pain relief starts 1–4 weeks after the initiation of treatment, continues for up to 18 months, and is associated with a reduction in analgesic use in many patients. Thrombocytopenia and neutropenia are the most common toxic effects, but they are generally mild and reversible. Repeat doses are effective in providing pain relief in many patients. The effectiveness of radioisotopes can be greater when they are combined with chemotherapeutic agents such as cisplatin. Some studies with 89Sr and 153Sm indicate a reduction of hot spots on bone scans in up to 70% of patients, and suggest a possible tumoricidal action. Further studies are needed to address the questions of which isotope to use, what dose and schedule to use, and which patients will respond.

The value of the latex agglutination test in meningitis was assessed. This was positive in 60% cases of Streptococcus pneumoniae, 93% of Haemophilus influenzae type b, and 39% of Neisseria meningitidis infections. We cannot support the view that this test was more valuable than Gram staining in partially treated meningitis and cannot recommend its routine use. It may, however, be valuable if Gram staining does not identify an organism or if it suggests meningococcal infection.

An 11-year-old male patient presents for an annual wellness examination. Medical history is significant for frequent ear infections as a toddler that resolved after tube placement. His review of systems is otherwise negative. Physical examination reveals normal height and weight for age with a body mass index in the 75th percentile.

In 1998, the U.S. poultry industry generated almost 12 million Mg of broiler (Gallus gallus domesticus) litter, most of which was applied to grasslands as fertilizer. This litter contains appreciable concentrations of estradiol and testosterone, sex hormones of environmental concern. We measured estradiol and testosterone concentrations in soil and runoff water from large (0.8 ha) grazed and ungrazed grasslands amended with broiler litter. Samples were analyzed by enzyme immunoassay. In runoff, background concentrations were 50 to 150 ng estradiol L super(-1) and 15 to 125 ng testosterone L super(-1). No significant differences were observed in runoff concentrations between hayed and grazed plots (p = 0.1). Therefore, grazing animals did not contribute hormones to runoff. When litter was applied, runoff concentrations were 20 to 2530 ng estradiol L super(-1) and 10 to 1830 ng testosterone L super(-1), depending on litter application rate and time between application and runoff. In soil, the background concentration for estradiol was 55 ng kg super(-1). Depending on litter application rate and time from application, the estradiol concentration in soil increased up to 675 ng kg super(-1). Testosterone followed a similar trend; however, concentrations of testosterone were significantly higher in grazed than in hayed plots (p = 0.1). These results show sizable edge-of-field losses of estradiol and testosterone from broiler litter-amended grasslands, and are the first studies to measure estradiol and testosterone in soil. Future research needs to examine the persistence and degradation of estradiol and testosterone in broiler litter, soil, and runoff.