The H II Region/PDR Connection: Self-Consistent Calculations of Physical Conditions in Star-Forming Regions

We have performed a series of calculations designed to reproduce infrared diagnostics used to determine physical conditions in star forming regions. We self-consistently calculate the thermal and chemical structure of an H II region and photodissociation region (PDR) that are in pressure equilibrium. This differs from previous work, which used separate calculations for each gas phase. Our calculations span a wide range of stellar temperatures, gas densities, and ionization parameters. We describe improvements made to the spectral synthesis code Cloudy that made these calculations possible. These include the addition of a molecular network with ~1000 reactions involving 68 molecular species and improved treatment of the grain physics. Data from the Spitzer First Look Survey, along with other archives, are used to derive important physical characteristics of the H II region and PDR. These include stellar temperatures, electron densities, ionization parameters, UV radiation flux, and PDR density. Finally, we calculate the contribution of the H II region to PDR emission line diagnostics, which allows for a more accurate determination of physical conditions in the PDR.Comment: 60 pages, 35 figures, to be published in the Astrophysical Journal. Version with full resolution is available at http://www.pa.uky.edu/~nicholas/hii_pdr_high_res.pd

Reaction bonded silicon nitride prepared from wet attrition-milled silicon

Silicon powder wet milled in heptane was dried, compacted into test bar shape, helium-sintered, and then reaction bonded in nitrogen-4 volume percent hydrogen. As-nitrided bend strengths averaged approximately 290 MPa at both room temperature and 1400 C. Fracture initiation appeared to be associated with subsurface flaws in high strength specimens and both subsurface and surface flaws in low strength specimens

Assessing the barriers and enablers to the implementation of the diagnostic radiographer musculoskeletal X‑ray reporting service within the NHS in England: a systematic literature review

Introduction The United Kingdom (UK) government’s healthcare policy in the early 1990s paved the way adoption of the skills mix development and implementation of diagnostic radiographers’ X-ray reporting service. Current clinical practice within the public UK healthcare system reflects the same pressures of increased demand in patient imaging and limited capacity of the reporting workforce (radiographers and radiologists) as in the 1990s. This study aimed to identify, define and assess the longitudinal macro, meso, and micro barriers and enablers to the implementation of the diagnostic radiographer musculoskeletal X-ray reporting service in the National Healthcare System (NHS) in England. Methods Multiple independent databases were searched, including PubMed, Ovid MEDLINE; Embase; CINAHL, and Google Scholar, as well as journal databases (Scopus, Wiley), healthcare databases (NHS Evidence Database; Cochrane Library) and grey literature databases (OpenGrey, GreyNet International, and the British Library EthOS depository) and recorded in a PRISMA flow chart. A combination of keywords, Boolean logic, truncation, parentheses and wildcards with inclusion/exclusion criteria and a time frame of 1995–2022 was applied. The literature was assessed against Joanna Briggs Institute’s critical appraisal checklists. With meta-aggregation to synthesize each paper, and coded using NVivo, with context grouped into macro, meso, and micro-level sources and categorised into subgroups of enablers and barriers. Results The wide and diverse range of data (n = 241 papers) identified barriers and enablers of implementation, which were categorised into measures of macro, meso, and micro levels, and thematic categories of context, culture, environment, and leadership. Conclusion The literature since 1995 has reframed the debates on implementation of the radiographer reporting role and has been instrumental in shaping clinical practice. There has been clear influence upon both meso (professional body) and macro-level (governmental/health service) policies and guidance, that have shaped change at micro-level NHS Trust organisations. There is evidence of a shift in culturally intrenched legacy perspectives within and between different meso-level professional bodies around skills mix acceptance and role boundaries. This has helped shape capacity building of the reporting workforce. All of which have contributed to conceptual understandings of the skills mix workforce within modern radiology services

A survey of the NHS reporting radiographer workforce in England

Introduction: At present there is no national register of the population size and scope of reporting radiographers in England. This makes operational workforce and succession planning for sustainable healthcare services in the National Health Service England (NHSE) difficult, affecting implementing NHSE policies and priorities such as 50% of X-rays reported by reporting radiographers and decreasing reporting Turnaround Times (TATs). This survey aimed to establish the workforce population employed as reporting radiographers in NHSE. Methods: An online anonymous seven question survey was distributed on social media and at the UK Imaging and Oncology Congress. Participant criteria included NHSE radiology staff (diagnostic radiographer, reporting radiographer, radiology manager, imaging superintendent modality lead, consultant radiologist, etc.) or a student diagnostic radiographer working within an NHSE trust. The survey recorded the participant's NHSE region (North Western, North Eastern and Yorkshire, Midlands, East of England, London, South Eastern and South Western regions), Integrated Care Systems (ICS), NHSE Trust, hospital, the amount of reporting radiographers and trainees employed, the Agenda for Change (AfC) job banding and imaging modality reported (X-ray, CT, MRI, NM, PET, DEXA). The data analysis applied descriptive statistics for estimating patterns and trends in the distribution of data (English region, AfC banding and imaging modality). Results: Responses were received from all seven of the NHSE regions (n=36/43 ICSs). The data demonstrated a larger workforce in the north of England than in the south, with employment at a range of AfC bandings from 5-8. The imaging modalities reported by radiographers in England demonstrated X-ray (n=34), the most reported imaging examination by region, and Nuclear Medicine (n=3) the least, with evidence of clinical reporting for CT (n=20), MRI (n=18), DEXA (n=16), Mammography (n=13) and fluoroscopy (n=12) being completed by radiographers in England. Conclusion: The findings for England (n=704 reporters; n=142 trainees) provide an estimate based on the response rate of the current reporting radiographer workforce across the NHSE regions, and their contribution to the skills mix radiology reporting service delivery. It is hoped future surveys will provide ongoing workforce estimates for the diagnostic radiographer reporting workforce in NHSE to support workforce transformation and sustainability plans for the radiography profession and to meet government healthcare targets and priorities

Accurate Realizations of the Ionized Gas in Galaxy Clusters: Calibrating Feedback

Using the full, three-dimensional potential of galaxy cluster halos (drawn from an N-body simulation of the current, most favored cosmology), the distribution of the X-ray emitting gas is found by assuming a polytropic equation of state and hydrostatic equilibrium, with constraints from conservation of energy and pressure balance at the cluster boundary. The resulting properties of the gas for these simulated redshift zero clusters (the temperature distribution, mass-temperature and luminosity-temperature relations, and the gas fraction) are compared with observations in the X-ray of nearby clusters. The observed properties are reproduced only under the assumption that substantial energy injection from non-gravitational sources has occurred. Our model does not specify the source, but star formation and AGN may be capable of providing this energy, which amounts to 3 to 5 x10^{-5} of the rest mass in stars (assuming ten percent of the gas initially in the cluster forms stars). With the method described here it is possible to generate realistic X-ray and Sunyaev-Zel'dovich cluster maps and catalogs from N-body simulations, with the distributions of internal halo properties (and their trends with mass, location, and time) taken into account.Comment: Matches ApJ published version; 30 pages, 7 figure

Epidemic spreading in evolving networks

A model for epidemic spreading on rewiring networks is introduced and analyzed for the case of scale free steady state networks. It is found that contrary to what one would have naively expected, the rewiring process typically tends to suppress epidemic spreading. In particular it is found that as in static networks, rewiring networks with degree distribution exponent $\gamma >3$ exhibit a threshold in the infection rate below which epidemics die out in the steady state. However the threshold is higher in the rewiring case. For $2<\gamma \leq 3$ no such threshold exists, but for small infection rate the steady state density of infected nodes (prevalence) is smaller for rewiring networks.Comment: 7 pages, 7 figure

CSF protein biomarkers predicting longitudinal reduction of CSF β-amyloid42 in cognitively healthy elders.

β-amyloid (Aβ) plaque accumulation is a hallmark of Alzheimer's disease (AD). It is believed to start many years prior to symptoms and is reflected by reduced cerebrospinal fluid (CSF) levels of the peptide Aβ1-42 (Aβ42). Here we tested the hypothesis that baseline levels of CSF proteins involved in microglia activity, synaptic function and Aβ metabolism predict the development of Aβ plaques, assessed by longitudinal CSF Aβ42 decrease in cognitively healthy people. Forty-six healthy people with three to four serial CSF samples were included (mean follow-up 3 years, range 2-4 years). There was an overall reduction in Aβ42 from a mean concentration of 211-195 pg ml(-1) after 4 years. Linear mixed-effects models using longitudinal Aβ42 as the response variable, and baseline proteins as explanatory variables (n=69 proteins potentially relevant for Aβ metabolism, microglia or synaptic/neuronal function), identified 10 proteins with significant effects on longitudinal Aβ42. The most significant proteins were angiotensin-converting enzyme (ACE, P=0.009), Chromogranin A (CgA, P=0.009) and Axl receptor tyrosine kinase (AXL, P=0.009). Receiver-operating characteristic analysis identified 11 proteins with significant effects on longitudinal Aβ42 (largely overlapping with the proteins identified by linear mixed-effects models). Several proteins (including ACE, CgA and AXL) were associated with Aβ42 reduction only in subjects with normal baseline Aβ42, and not in subjects with reduced baseline Aβ42. We conclude that baseline CSF proteins related to Aβ metabolism, microglia activity or synapses predict longitudinal Aβ42 reduction in cognitively healthy elders. The finding that some proteins only predict Aβ42 reduction in subjects with normal baseline Aβ42 suggest that they predict future development of the brain Aβ pathology at the earliest stages of AD, prior to widespread development of Aβ plaques