Electron Diagnostics for Extreme High Brightness Nano-Blade Field Emission Cathodes

Electron beams are essential tools in modern science. They are ubiquitous in fields ranging from microscopy to the creation of coherent ultra-fast X-rays to lithography. To keep pace with demand, electron beam brightness must be continually increased. One of the main strategic aims of the Center for Bright Beams (CBB), a National Science Foundation Science and Technology Center, is to increase brightness from photocathodes by two orders of magnitude. Improving the state-of-the-art for photoemission-based cathodes is one possibility. Several factors have led to an alternative design becoming an increasing necessity; the nanoscale structure. Field emission sources from nano-tips would be an ideal candidate were it not for their low current and damage threshold. A 1-dimensional extended nano-fabricated blade, i.e., a projected tip, can solve the problems inherent in both designs. The novel geometry has been demonstrated to produce extremely high brightness electron beam bunches and is significantly more robust and easier to manufacture than traditional photocathodes. Theory indicates electron emission up to keV energies. We thus present a system of diagnostics capable of analyzing the cathodes and assessing their viability. The diagnostics are designed to measure the electron spectrum up to keV energies, with sub meV resolution at <100 eV, mean transverse energy (MTE), emission uniformity, and cathode lifetime. We also report preliminary data on total extracted charge and maximum detectable electron energy with a simplified retarding field spectrometer

Verbatim Theater: Prompting Reflection and Discussion about Healthcare Culture as a Means of Promoting Culture Change

Problem: The mistreatment of medical and nursing students and junior health professionals has been reported internationally in research and the media. Mistreatment can be embedded and normalized in hierarchical healthcare workplaces, limiting the effectiveness of policies and reporting tools to generate change; as a result, some of those who experience mistreatment later perpetuate it. We used a novel, creative approach, verbatim theater, to highlight the complexity of healthcare workplaces, encourage critical reflection, and support long-term culture change. Intervention: Verbatim theater is a theater-for-change documentary genre in which a playscript is devised using only the words spoken by informants. In 2017, 30 healthcare students and health professionals were recruited and interviewed about their experience of work and training by the multidisciplinary Sydney Arts and Health Collective using semi-structured interviews. Interview transcripts became the primary material from which the script for the verbatim theater play ‘Grace Under Pressure’ was developed. The performing arts have previously been used to develop the communication skills of health professional students; this esthetic expression of the real-life effects of healthcare workplace culture on trainees and students was implemented to stimulate consciousness of, and dialogue about, workplace mistreatment in healthcare work and training. Context: The play premiered at a major Sydney theater in October 2017, attended by the lay public and student and practicing health professionals. In November 2017, three focus groups were held with a sample of audience members comprising healthcare professionals and students. These focus groups explored the impact of the play on reflection and discussion of healthcare culture and/or promoting culture change in the health workplace. We analyzed the focus group data using theoretical thematic analysis, informed by Turner’s theory of the relation between ‘social’ and ‘esthetic’ drama to understand the impact of the play on its audience. Impact: Focus group members recognized aspects of their personal experience of professionalism, training, and workplace culture in the play, Grace Under Pressure. They reported that the play’s use of real-life stories and authentic language facilitated their critical reflection. Participants constructed some learning as ‘revelation,’ in which the play enabled them to gain significant new insight into the culture of health care and opened up discussions with colleagues. As a result, participants suggested possible remedies for unhealthy aspects of the culture, including systemic issues of bullying and harassment. A small number of participants critiqued aspects of the play they believed did not adequately reflect their experience, with some believing that the play over-emphasized workplace mistreatment. Lessons Learned: Verbatim theater is a potent method for making personal experiences of healthcare workplace and training culture more visible to lay and health professional audiences. In line with Turner’s theory, the play’s use of real-life stories and authentic language enabled recognition of systemic challenges in healthcare workplaces by training and practicing health professionals in the audience. Verbatim theater provides a means to promote awareness and discussion of difficult social issues and potential means of addressing them

Analyses of SRS waste glass buried in granite in Sweden and salt in the United States

Simulated Savannah River Site (SRS) waste glass forms have been buried in the granite geology of the Stirpa mine in Sweden for two years. Analyses of glass surfaces provided a measure of the performance of the waste glasses as a function of time. Similar SRS waste glass compositions have also been buried in salt at the WIPP facility in Carlsbad, New Mexico for a similar time period. Analyses of the SRS waste glasses buried in-situ in granite will be presented and compared to the performance of these same compositions buried in salt at WIPP

SARS-CoV-2 surveillance in households with and without asthmatic/allergic children: The Human Epidemiology and Response to SARS-CoV-2 study (HEROS)

Rationale: Whether children and people with asthma and allergic diseases are at increased risk for SARS-CoV-2 infection is not known. Neither is their role in household transmission. Methods: Biweekly nasal sample collections and weekly surveys were conducted to identify incident SARS-CoV-2 infections among children (\u3c13 \u3eyears) and teenagers (13-21 years) enrolled in asthma/allergic disease focused cohorts, and their household members, from May 2020-February 2021. Probability of subject/household infections and household transmissions were calculated using time-to-event analyses, and factors associated with infection and transmission risk using regression analyses. Results: Household (N=1,394) and subject (N=4,142) SARS-CoV-2 infection probability was 25.8% and 14.0%, respectively, and was similar for children (14.0%,CI:8.0-19.6%), teenagers (12.1%,CI:8.2-15.9%), and adults (14.0%,CI:9.5-18.4%). Infections were symptomatic in 24.5% of children, 41.2% of teenagers, and 62.5% of adults. Exposure to both symptomatic (aHR=87.39,CI:58.02-131.63) and asymptomatic (aHR=27.80,CI:17.16–45.03) infected household members was a risk factor for infection. Food allergy was associated with decreased infection risk (aHR=0.50,CI:0.32-0.81), but asthma was not (aHR=1.04,CI:0.73-1.46). Household infection risk was associated with attending in-person school (aHR=1.67,CI:1.09-2.57). Household secondary attack rate was 57.7%. Decreased risk of household transmission was associated with teen age, lower BMI, and lower viral load. Conclusions: Asthma does not increase risk of SARS-CoV-2 infection, while food allergy is protective. SARS-CoV-2 infection risk in children is similar to that of teenagers and adults. SARS-CoV-2 transmission risk and secondary attack rate is much higher than previously estimated in households with children, likely driven by the high frequency of asymptomatic childhood infections

River bank burrowing by invasive crayfish: Spatial distribution, biophysical controls and biogeomorphic significance

Invasive species generate significant global environmental and economic costs and represent a particularly potent threat to freshwater systems. The biogeomorphic impacts of invasive aquatic and riparian species on river processes and landforms remain largely unquantified, but have the potential to generate significant sediment management issues within invaded catchments. Several species of invasive (non-native) crayfish are known to burrow into river banks and visual evidence of river bank damage is generating public concern and media attention. Despite this, there is a paucity of understanding of burrow distribution, biophysical controls and the potential significance of this problem beyond a small number of local studies at heavily impacted sites. This paper presents the first multi-catchment analysis of this phenomenon, combining existing data on biophysical river properties and invasive crayfish observations with purpose-designed field surveys across 103 river reaches to derive key trends. Crayfish burrows were observed on the majority of reaches, but burrowing tended to be patchy in spatial distribution, concentrated in a small proportion (< 10%) of the length of rivers surveyed. Burrow distribution was better explained by local bank biophysical properties than by reach-scale properties, and burrowed banks were more likely to be characterised by cohesive bank material, steeper bank profiles with large areas of bare bank face, often on outer bend locations. Burrow excavation alone has delivered a considerable amount of sediment to invaded river systems in the surveyed sites (3 t km− 1 impacted bank) and this represents a minimum contribution and certainly an underestimate of the absolute yield (submerged burrows were not recorded). Furthermore, burrowing was associated with bank profiles that were either actively eroding or exposed to fluvial action and/or mass failure processes, providing the first quantitative evidence that invasive crayfish may cause or accelerate river bank instability and erosion in invaded catchments beyond the scale of individual burro

Measurement of the jet mass in highly boosted t(t)over-bar events from pp collisions at root s=8TeV

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