Documentation for the token ring network simulation system

A manual is presented which describes the language features of the Token Ring Network Simulation System. The simulation system is a powerful simulation tool for token ring networks which allows the specification of various Medium Access Control (MAC) layer protocols as well as the specification of various features of upper layer ISO protocols. In addition to these features, it also allows the user to specify message and station classes virtually to any degree of detail desired. The choice of a language instead of an interactive system to specify network parameters was dictated by both flexibility and time considerations. The language was developed specifically for the simulation system, and is very simple. It is also user friendly in that language elements which do not apply to the case at hand are ignored rather than treated as errors

Anomalous Behavior of Ru for Catalytic Oxidation: A Theoretical Study of the Catalytic Reaction CO + 1/2 O_2 --> CO_2

Recent experiments revealed an anomalous dependence of carbon monoxide oxidation at Ru(0001) on oxygen pressure and a particularly high reaction rate. Below we report density functional theory calculations of the energetics and reaction pathways of the speculated mechanism. We will show that the exceptionally high rate is actuated by a weakly but nevertheless well bound (1x1) oxygen adsorbate layer. Furthermore it is found that reactions via scattering of gas-phase CO at the oxygen covered surface may play an important role. Our analysis reveals, however, that reactions via adsorbed CO molecules (the so-called Langmuir-Hinshelwood mechanism) dominate.Comment: 5 pages, 4 figures, Phys. Rev. Letters, Feb. 1997, in prin

The steady-state of heterogeneous catalysis, studied by first-principles statistical mechanics

The turn-over frequency of the catalytic oxidation of CO at RuO2(110) was calculated as function of temperature and partial pressures using ab initio statistical mechanics. The underlying energetics of the gas-phase molecules, dissociation, adsorption, surface diffusion, surface chemical reactions, and desorption were obtained by all-electron density-functional theory. The resulting CO2 formation rate [in the full (T, p_CO, p_O2)-space], the movies displaying the atomic motion and reactions over times scales from picoseconds to seconds, and the statistical analyses provide insights into the concerted actions ruling heterogeneous catalysis and open thermodynamic systems in general.Comment: 4 pages including 3 figures, Related publications can be found at http://www.fhi-berlin.mpg.de/th/paper.htm

First-principles, atomistic thermodynamics for oxidation catalysis

Present knowledge of the function of materials is largely based on studies (experimental and theoretical) that are performed at low temperatures and ultra-low pressures. However, the majority of everyday applications, like e.g. catalysis, operate at atmospheric pressures and temperatures at or higher than 300 K. Here we employ ab initio, atomistic thermodynamics to construct a phase diagram of surface structures in the (T,p)-space from ultra-high vacuum to technically-relevant pressures and temperatures. We emphasize the value of such phase diagrams as well as the importance of the reaction kinetics that may be crucial e.g. close to phase boundaries.Comment: 4 pages including 2 figure files. Submitted to Phys. Rev. Lett. Related publications can be found at http://www.fhi-berlin.mpg.de/th/paper.htm

Pre-Existing Medical Conditions: A Systematic Literature Review of a Silent Contributor to Adult Drowning

Abstract: Medical conditions can increase drowning risk. No prior study has systematically reviewed the published evidence globally regarding medical conditions and drowning risk for adults. MEDLINE (Ovid), PubMed, EMBASE, Scopus, PsycINFO (ProQuest) and SPORTDiscus databases were searched for original research published between 1 January 2005 and 31 October 2021 that reported adult (>=15 years) fatal or non-fatal drowning of all intents and pre-existing medical conditions. Conditions were grouped into the relevant International Classifications of Diseases (ICD) codes. Eighty-three studies were included (85.5% high-income countries; 38.6% East Asia and Pacific region; 75.9% evidence level III-3). Diseases of the nervous system (n = 32 studies; 38.6%), mental and behavioural conditions (n = 31; 37.3%) and diseases of the circulatory system (n = 25; 30.1%) were the most common categories of conditions. Epilepsy was found to increase the relative risk of drowning by 3.8 to 82 times, with suggested preventive approaches regarding supervised bathing or showering. Drowning is a common suicide method for those with schizophrenia, psychotic disorders and dementia. Review findings indicate people with pre-existing medical conditions drown, yet relatively few studies have documented the risk. There is a need for further population-level research to more accurately quantify drowning risk for pre-existing medical conditions in adults, as well as implementing and evaluating population-level attributable risk and prevention strategies

Aquatic competencies and drowning prevention in children 2–4 years: a systematic review

Aquatic competencies have been proposed as a prevention strategy for children aged 2–4 years who are over-represented in drowning statistics. For this recommendation to be made, exploration of the connection between aquatic competencies and drowning is required. This review critically analyzed studies exploring aquatic competencies and their effect on drowning and/or injury severity in children 2–4 years. English language peer-reviewed literature up to 31 July 2019 was searched and the PRISMA process utilized. Data were extracted from twelve studies that fulfilled the inclusion criteria. Findings from this study included that aquatic competencies were not found to increase risk of drowning and demonstrated children aged 2–4 years are capable of developing age-appropriate aquatic competencies. Age-appropriate aquatic competencies extracted were propulsion/locomotion, flotation/buoyancy, water familiarization, submersion and water exits. The acquisition of these competencies holds benefit for the prevention of drowning. No evidence was found relating to injury severity. There was limited exploration of the relationship between aquatic competencies attainment and age-related developmental readiness. The review highlights the need for consistent measures of exposure, clarity around skills acquisition, better age-specific data (2 years vs. 3 years vs. 4 years), studies with larger sample sizes, further exploration of the dose–response relationship and consistent skill level testing across age groups. Further investigation is required to establish the efficacy of aquatic competencies as a drowning prevention intervention, as well as exploring the relationship between aquatic competencies and age-related developmental readiness. In conclusion, early evidence suggests aquatic competencies can help to reduce drowning

Disadvantaged by More Than Distance: A Systematic Literature Review of Injury in Rural Australia

Rural populations experience injury-related mortality and morbidity rates 1.5 times greater than metropolitan residents. Motivated by a call for stronger epidemiological evidence around rural injuries to inform prevention, a systematic review of peer-reviewed literature published between January 2010 and March 2021 was undertaken to explore the epidemiology of rural injury and associated risk factors in Australia. A subsequent aim was to explore definitions of rurality used in injury prevention studies. There were 151 papers included in the review, utilizing 23 unique definitions to describe rurality. People living in rural areas were more likely to be injured, for injuries to be more severe, and for injuries to have greater resulting morbidity than people in metropolitan areas. The increase in severity reflects the mechanism of rural injury, with rural injury events more likely to involve a higher energy exchange. Risk-taking behavior and alcohol consumption were significant risk factors for rural injury, along with rural cluster demographics such as age, sex, high socio-economic disadvantage, and health-related comorbidities. As injury in rural populations is multifactorial and nonhomogeneous, a wide variety of evidence-based strategies are needed. This requires funding, political leadership for policy formation and development, and implementation of evidence-based prevention interventions

Hypoxic Blackout: Diagnosis, Risks, and Prevention

Hypoxic blackout, also called underwater blackout syndrome, is a distinct and preventable cause of drowning. The sudden and unexpected death of a young, fit swimmer or diver, almost always male, necessitates the consideration of a differential diagnosis which includes four syndromes—preexistent cardiac disease, electrical conduction abnormalities, epilepsy, and hypoxic blackout. The pathophysiology of hypoxic blackout (overriding the carbon dioxide sensor by presubmersion hyperventilation) may be induced by autonomic conflict between cold shock diving reflexes in certain predisposed individuals. Death occurs in both public and private swimming pools and in the sea, and case series include those training for underwater hockey, synchronized swimming, free diving, and playful submersion endurance challenges. The sole preventive stratagem is advocacy for awareness of risks, suitably targeted to “at risk” groups

Theoretical study of O adlayers on Ru(0001)

Recent experiments performed at high pressures indicate that ruthenium can support unusually high concentrations of oxygen at the surface. To investigate the structure and stability of high coverage oxygen structures, we performed density functional theory calculations, within the generalized gradient approximation, for O adlayers on Ru(0001) from low coverage up to a full monolayer. We achieve quantitative agreement with previous low energy electron diffraction intensity analyses for the (2x2) and (2x1) phases and predict that an O adlayer with a (1x1) periodicity and coverage of 1 monolayer can form on Ru(0001), where the O adatoms occupy hcp-hollow sites.Comment: RevTeX, 6 pages, 4 figure

Fatal, unintentional drowning in older people: an assessment of the role of preexisting medical conditions

Background: The number of older people (aged 65 y and over) is increasing in Australia and chronic medical conditions are common. Aquatic activities provide physical and social benefits; however, understanding the risks related to aquatic activity is important for ongoing health and wellbeing. We explore the impact of preexisting medical conditions on unintentional fatal drowning among older people in Australia. Methods: Using coronial, forensic, and medical histories from the Australian National Coronial Information System, all cases of unintentional death by drowning (or where drowning was a factor) among older people in Australia between July 1, 2002 and June 30, 2012 were investigated. Preexisting medical conditions were reviewed to determine whether they were contributory to drowning. Results: Of the 506 older people who drowned, 69.0% had a preexisting medical condition. The leading contributory medical condition was cardiovascular disease, followed by dementia, depression, epilepsy, and Parkinson disease. All conditions except cardiovascular disease and depression were overrepresented compared with the proportion of the disease in the population. Falling into water was the most common activity immediately before drowning, especially among those with dementia, whereas those with cardiovascular disease were most likely to drown while swimming. Conclusions: Preexisting medical conditions contribute to drowning in older people but with unequal contributions. With the prevalence of medical conditions expected to increase as the population ages, targeted education for older people will be important. Risk management will enable older people to safely participate in aquatic activities