A study of chemistry, dynamics and dust in nova outflows

Since the celebrated outburst of nova DQ Herculis (1936), observations of which suggested that dust grains were being formed with high efficiency, research into the chemical processes leading to dust nucleation has flourished. Observations show that dust formation is not only highly efficient but a common occurrence in nova outbursts, yet the chemical pathways leading to dust are poorly understood. A study of chemical processes within outflowing ejectum material through closely linked, quasi self-consistent chemical models from just a few days post-outburst until the formation of dust nucleation sites is presented. Chemical modelling, incorporating new and updated chemistry within a realistic radiation field, is followed by a study of dynamics with a now fluid dynamic model incorporating chemistry explicitly within the conservation equations. In contrast to previous studies, we find that a rich chemistry of small molecules develops within a few days after outburst. This leads to the formation of a large abundance of nucleation sites from many model configurations. We find also that CO does not saturate within these chemical scenarios; this negates previous assumptions and helps to explain observations not only in novae, but also in objects such as planetary nebulae. Constraints are placed on physical conditions within the ejecta. Two outflow configurations are modelled with a simplified chemistry embedded in a fluid dynamic code. We suggest an explanation for the time-dependent behaviour of CO molecular lines observed in nova V705 Cas, and further constrain the physical parameters for this nova. It is found that, as a result of the dynamics, a rich chemistry may occur only within localised regions of the principal ejectum and that the results are consistent with observation. It is suggested that further development of this model, particularly with respect to the radiation field, will lead to a deeper understanding of both physical and chemical processes within nova outflows

Impact Craters as Habitats for Life: Endolithic Colonization of Shocked Gneiss from the Haughton Impact Structure, Devon Island, Canada

Meteorite impacts are ubiquitous throughout our solar system and are a fundamental geological process on rocky and icy planetary bodies. Though initially detrimental to biology, an impact event can favourably change the availability and habitability of a substrate for endolithic organisms, which are then able to (re)colonize micro-fractures and pore spaces created during the impact. The colonization of rocks by endolithic communities is an advantageous trait, especially in environments such as hot or cold deserts, where temperature shifts, low water availability and high UV indices pose a significant problem. On Mars, similar conditions – albeit, more extreme – prevail. In these instances, impact structures could provide refuge to endolithic organisms. Previous work has shown the increase of microbial biomass with shock level in sedimentary rocks, related to increases in porosity. However, sedimentary rocks experience a collapse of pore spaces at pressures over ~35 GPa and, thus, do not support endolithic colonization at pressures higher than this. In contrast, the porosity of crystalline rocks such as gneisses increases proportionally until vapourization. This study considers shocked gneisses from the 39 Ma, 23 km diameter Haughton impact structure, Devon Island, Canada, and investigates the relationship between shock metamorphism and microbial colonization. Utilizing a variety of microscopy techniques, the subsurface community was visualized and the biomass levels calculated with increasing shock metamorphism. Average cell abundance was found to increase with shock level, with a maximum of 108 cells/g. It was found that microbial biomass did increase with increasing porosity, and was not affected by reductions in trace element concentrations of the rock, likely being more dependent on exogenous nutrients within meteoric waters or supplied aerially. It can be concluded that crystalline substrates can become habitats for endolithic organisms through the process of impact metamorphism, providing an excellent refuge in extreme environments. On Mars where the substrate is largely basaltic, it is suggested that impact craters would be an excellent target for life detection due to extensive deposits of shocked basalt. These more mafic rocks, coupled with the presence of hydrothermal activity, would have potentially provided significant colonization potential on early Mars and may continue to provide refuge today

The impact of computerised physician order entry with integrated clinical decision support on pharmacist-physician communication in the hospital setting

An analysis of over 34,000 free-text messages assigned by pharmacists to prescription orders over a 12-month period showed a sub-optimal exchange of information with the physician. Focus groups and observational research were conducted to provide a more in-depth understanding of the factors involved. The use of CPOE did not reduce opportunities for personal interaction. The capability to communicate electronically facilitated a non-interruptive workflow, beneficial for staff time and for limiting distractions. It also improved clinical documentation, which helped coordinate care of patients between members of the pharmacy team. However, the research identified several barriers to the effectiveness of communication via the CPOE system, including: the increased frequency of messages sent; poor display characteristics of the message; poor access to information to inform decision-making; one-way communication; and no assigned responsibility to respond. These factors need to be considered in the design of systems and supported by interprofessional training to optimise communication between the professionals

Role of Meteorite Impacts in the Origin of Life

The conditions, timing, and setting for the origin of life on Earth and whether life exists elsewhere in our solar system and beyond represent some of the most fundamental scientific questions of our time. Although the bombardment of planets and satellites by asteroids and comets has long been viewed as a destructive process that would have presented a barrier to the emergence of life and frustrated or extinguished life, we provide a comprehensive synthesis of data and observations on the beneficial role of impacts in a wide range of prebiotic and biological processes. In the context of previously proposed environments for the origin of life on Earth, we discuss how meteorite impacts can generate both subaerial and submarine hydrothermal vents, abundant hydrothermal–sedimentary settings, and impact analogues for volcanic pumice rafts and splash pools. Impact events can also deliver and/or generate many of the necessary chemical ingredients for life and catalytic substrates such as clays as well. The role that impact cratering plays in fracturing planetary crusts and its effects on deep subsurface habitats for life are also discussed. In summary, we propose that meteorite impact events are a fundamental geobiological process in planetary evolution that played an important role in the origin of life on Earth. We conclude with the recommendation that impact craters should be considered prime sites in the search for evidence of past life on Mars. Furthermore, unlike other geological processes such as volcanism or plate tectonics, impact cratering is ubiquitous on planetary bodies throughout the Universe and is independent of size, composition, and distance from the host star. Impact events thus provide a mechanism with the potential to generate habitable planets, moons, and asteroids throughout the Solar System and beyond

Evaluation of uncomplicated acute respiratory tract infection management in veterans: A national utilization review.

BackgroundAntibiotics are overprescribed for acute respiratory tract infections (ARIs). Guidelines provide criteria to determine which patients should receive antibiotics. We assessed congruence between documentation of ARI diagnostic and treatment practices with guideline recommendations, treatment appropriateness, and outcomes.MethodsA multicenter quality improvement evaluation was conducted in 28 Veterans Affairs facilities. We included visits for pharyngitis, rhinosinusitis, bronchitis, and upper respiratory tract infections (URI-NOS) that occurred during the 2015-2016 winter season. A manual record review identified complicated cases, which were excluded. Data were extracted for visits meeting criteria, followed by analysis of practice patterns, guideline congruence, and outcomes.ResultsOf 5,740 visits, 4,305 met our inclusion criteria: pharyngitis (n = 558), rhinosinusitis (n = 715), bronchitis (n = 1,155), URI-NOS (n = 1,475), or mixed diagnoses (>1 ARI diagnosis) (n = 402). Antibiotics were prescribed in 68% of visits: pharyngitis (69%), rhinosinusitis (89%), bronchitis (86%), URI-NOS (37%), and mixed diagnosis (86%). Streptococcal diagnostic testing was performed in 33% of pharyngitis visits; group A Streptococcus was identified in 3% of visits. Streptococcal tests were ordered less frequently for patients who received antibiotics (28%) than those who did not receive antibiotics 44%; P < .01). Although 68% of visits for rhinosinusitis had documentation of symptoms, only 32% met diagnostic criteria for antibiotics. Overall, 39% of patients with uncomplicated ARIs received appropriate antibiotic management. The proportion of 30-day return visits for ARI care was similar for appropriate (11%) or inappropriate (10%) antibiotic management (P = .22).ConclusionsAntibiotics were prescribed in most uncomplicated ARI visits, indicating substantial overuse. Practice was frequently discordant with guideline diagnostic and treatment recommendations