Prehospital central venous catheters.

The use of whole blood in the prehospital setting is increasing. Currently available intraosseous and peripheral venous catheters limit the flow of blood products and fluid during resuscitation. Central venous catheters can be effectively placed in the prehospital environment. Rapid, high-volume infusion of blood products can be lifesaving.

Wilderness Medical Society Clinical Practice Guidelines for the Treatment of Acute Pain in Austere Environments: 2024 Update.

The Wilderness Medical Society (WMS) convened an expert panel to develop evidence-based guidelines for the management of pain in austere environments. Recommendations are graded based on the quality of supporting evidence as defined by criteria put forth by the American College of Chest Physicians. This is an update of the 2014 version of the "WMS Practice Guidelines for the Treatment of Acute Pain in Remote Environments" published in Wilderness & Environmental Medicine 2014; 25:41-49.

The Ethics of Risk Prediction for Psychosis and Suicide Attempt in Youth Mental Health.

OBJECTIVE: To identify potential clinical utility of polygenic risk scores (PRS) and exposomic risk scores (ERS) for psychosis and suicide attempt in youth and assess the ethical implications of these tools. STUDY DESIGN: We conducted a narrative literature review of emerging findings on PRS and ERS for suicide and psychosis as well as a literature review on the ethics of PRS. We discuss the ethical implications of the emerging findings for the clinical potential of PRS and ERS. RESULTS: Emerging evidence suggests that PRS and ERS may offer clinical utility in the relatively near future but that this utility will be limited to specific, narrow clinical questions, in contrast to the suggestion that population-level screening will have sweeping impact. Combining PRS and ERS might optimize prediction. This clinical utility would change the risk-benefit balance of PRS, and further empirical assessment of proposed risks would be necessary. Some concerns for PRS, such as those about counseling, privacy, and inequities, apply to ERS. ERS raise distinct ethical challenges as well, including some that involve informed consent and direct-to-consumer advertising. Both raise questions about the ethics of machine-learning/artificial intelligence approaches. CONCLUSIONS: Predictive analytics using PRS and ERS may soon play a role in youth mental health settings. Our findings help educate clinicians about potential capabilities, limitations, and ethical implications of these tools. We suggest that a broader discussion with the public is needed to avoid overenthusiasm and determine regulations and guidelines for use of predictive scores.

Moral expertise without moral elitism.

Skepticism about ethical expertise has grown common, raising concerns that bioethicists' roles are inappropriate or depend on something other than expertise in ethics. While these roles may depend on skills other than those of expertise, overlooking the role of expertise in ethics distorts our conception of moral advising. This paper argues that motivations to reject ethical expertise often stem from concerns about elitism: either an intellectualist elitism, where some privileged elite have supposedly special access in virtue of expertise in moral theory; or an authoritarian elitism, where our reliance on experts in ethics risks violation of autonomy and democracy. The paper sketches an anti-elitist conception of ethics expertise in bioethics as continuous with an anti-elitist conception of ethics expertise in common moral practice, undercutting the intellectualism, and then uses this anti-elitist conception to reject arguments that ethical expertise violates autonomy or democracy. An anti-elitist picture of ethical expertise both renders it consistent with our general moral practice and allows us to resist skeptical concerns.

Religious pluralism and the ethics of healthcare.

Democratic societies that separate church and state face major challenges in accommodating religious convictions. This applies especially to determining healthcare policies. Building on our prior work on the demands and limits of religious accommodation in democratic societies, we propose a set of ethical standards that can guide societies in meeting this challenge. In applying and defending these standards, we explore three topics: vaccine resistance, abortion, and concerns about rights to healthcare. We clarify these and other issues of religious accommodation and propose ethical standards for approaching these and other problems.

Atomistic simulation framework for molten salt vapor-liquid equilibrium prediction and its application to NaCl.

Knowledge of the vapor-liquid equilibrium (VLE) properties of molten salts is important in the design of thermal energy storage systems for solar power and nuclear energy production applications. The high temperatures involved make their experimental determination problematic, and the development of both macroscopic thermodynamic correlations and predictive molecular-based methodologies are complicated by the requirement to appropriately incorporate the chemically reacting vapor-phase species. We derive a general thermodynamic-based atomistic simulation framework for molten salt VLE prediction and show its application to NaCl. Its input quantities are temperature-dependent ideal-gas free energy data for the vapor phase reactions and density and residual chemical potential data for the liquid. If these are not available experimentally, the former may be predicted using standard electronic structure software, and the latter may be predicted by means of classical atomistic simulation methodology. The framework predicts the temperature dependence of vapor pressure, coexisting phase densities, vapor phase composition, and vaporization enthalpy. It also predicts the concentrations of vapor phase species present in minor amounts (such as the free ions), quantities that are extremely difficult to measure experimentally. We furthermore use the results to obtain an approximation to the complete VLE binodal dome and the critical properties. We verify the framework for molten NaCl, for which experimentally based density and chemical potential data are available in the literature. We then apply it to the analysis of NaCl simulation data for two commonly used atomistic force fields. The framework can be readily extended to molten salt mixtures and to ionic liquids.

Force-Field-Based Computational Study of the Thermodynamics of a Large Set of Aqueous Alkanolamine Solvents for Post-Combustion CO2 Capture.

The ability to predict the thermodynamic properties of amine species in CO2-loaded aqueous solutions, including their deprotonation (pKa) and carbamate to bicarbonate reversion (pKc) equilibrium constants and their corresponding standard reaction enthalpies, is of critical importance for the design of improved carbon capture solvents. In this study, we used isocoulombic forms of both reactions to determine these quantities for a large set of aqueous alkanolamine solvent systems. Our hybrid approach involves using classical molecular dynamics simulations with the general amber force field (GAFF) and semi-empirical AM1-BCC charges (GAFF/AM1-BCC) in the solution phase, combined with high-level composite quantum chemical ideal-gas calculations. We first determined a new force field (FF) for the hydronium ion (H3O+) by matching to the single experimental pKa data point for the well-known monoethanolamine system at 298.15 K. We then used this FF to predict the pKa values for 76 other amines at 298.15 K and for all 77 amines at elevated temperatures. Additionally, we indirectly relate the H3O+ hydration free energy to that of H+ and provide expressions for intrinsic hydration free energy and enthalpy of the proton. Using the derived H3O+ FF, we predicted the pKa values of a diverse set of alkanolamines with an overall average absolute deviation of less than 0.72 pKa units. Furthermore, the derived H3O+ FF is able to predict the protonation enthalpy of these amines when used with the GAFF. We also predicted the carbamate reversion constants of the primary and secondary amine species in the data set and their corresponding standard heats of reaction, which we compared with the scarcely available experimental data, which are often subject to significant uncertainty. Finally, we also described the influence of electronic and steric effects of different molecular fragments/groups on the stabilities of the carbamates.

Religious Accommodation in Bioethics and the Practice of Medicine.

Debates about the ethics of health care and medical research in contemporary pluralistic democracies often arise partly from competing religious and secular values. Such disagreements raise challenges of balancing claims of religious liberty with claims to equal treatment in health care. This paper proposes several mid-level principles to help in framing sound policies for resolving such disputes. We develop and illustrate these principles, exploring their application to conscientious objection by religious providers and religious institutions, accommodation of religious priorities in biomedical research, and treatment of patients' religious views in doctor-patient encounters. Given that no sound set of guiding principles yields precise solutions for every policy dispute, we explore how morally sound democracies might deliberatively resolve such policy issues, following our proposed principles. Taken together and carefully interpreted, these principles may help in guiding difficult decision making in the indefinitely large realm where government, medical providers, and patients encounter problems concerning religion and medicine.

Uterotonic agents for first-line treatment of postpartum haemorrhage: a network meta-analysis.

BACKGROUND: Postpartum haemorrhage (PPH), defined as a blood loss of 500 mL or more after birth, is the leading cause of maternal death worldwide. The World Health Organization (WHO) recommends that all women giving birth should receive a prophylactic uterotonic agent. Despite the routine administration of a uterotonic agent for prevention, PPH remains a common complication causing one-quarter of all maternal deaths globally. When prevention fails and PPH occurs, further administration of uterotonic agents as 'first-line' treatment is recommended. However, there is uncertainty about which uterotonic agent is best for the 'first-line' treatment of PPH. OBJECTIVES: To identify the most effective uterotonic agent(s) with the least side-effects for PPH treatment, and generate a meaningful ranking among all available agents according to their relative effectiveness and side-effect profile. SEARCH METHODS: We searched the Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (5 May 2020), and the reference lists of all retrieved studies. SELECTION CRITERIA: All randomised controlled trials or cluster-randomised trials comparing the effectiveness and safety of uterotonic agents with other uterotonic agents for the treatment of PPH were eligible for inclusion. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed all trials for inclusion, extracted data and assessed each trial for risk of bias. Our primary outcomes were additional blood loss of 500 mL or more after recruitment to the trial until cessation of active bleeding and the composite outcome of maternal death or severe morbidity. Secondary outcomes included blood loss-related outcomes, morbidity outcomes, and patient-reported outcomes. We performed pairwise meta-analyses and indirect comparisons, where possible, but due to the limited number of included studies, we were unable to conduct the planned network meta-analysis. We used the GRADE approach to assess the certainty of evidence. MAIN RESULTS: Seven trials, involving 3738 women in 10 countries, were included in this review. All trials were conducted in hospital settings. Randomised women gave birth vaginally, except in one small trial, where women gave birth either vaginally or by caesarean section. Across the seven trials (14 trial arms) the following agents were used: six trial arms used oxytocin alone; four trial arms used misoprostol plus oxytocin; three trial arms used misoprostol; one trial arm used Syntometrine® (oxytocin and ergometrine fixed-dose combination) plus oxytocin infusion. Pairwise meta-analysis of two trials (1787 participants), suggests that misoprostol, as first-line treatment uterotonic agent, probably increases the risk of blood transfusion (risk ratio (RR) 1.47, 95% confidence interval (CI) 1.02 to 2.14, moderate-certainty) compared with oxytocin. Low-certainty evidence suggests that misoprostol administration may increase the incidence of additional blood loss of 1000 mL or more (RR 2.57, 95% CI 1.00 to 6.64). The data comparing misoprostol with oxytocin is imprecise, with a wide range of treatment effects for the additional blood loss of 500 mL or more (RR 1.66, 95% CI 0.69 to 4.02, low-certainty), maternal death or severe morbidity (RR 1.98, 95% CI 0.36 to 10.72, low-certainty, based on one study n = 809 participants, as the second study had zero events), and the use of additional uterotonics (RR 1.30, 95% CI 0.57 to 2.94, low-certainty). The risk of side-effects may be increased with the use of misoprostol compared with oxytocin: vomiting (2 trials, 1787 participants, RR 2.47, 95% CI 1.37 to 4.47, high-certainty) and fever (2 trials, 1787 participants, RR 3.43, 95% CI 0.65 to 18.18, low-certainty). According to pairwise meta-analysis of four trials (1881 participants) generating high-certainty evidence, misoprostol plus oxytocin makes little or no difference to the use of additional uterotonics (RR 0.99, 95% CI 0.94 to 1.05) and to blood transfusion (RR 0.95, 95% CI 0.77 to 1.17) compared with oxytocin. We cannot rule out an important benefit of using the misoprostol plus oxytocin combination over oxytocin alone, for additional blood loss of 500 mL or more (RR 0.84, 95% CI 0.66 to 1.06, moderate-certainty). We also cannot rule out important benefits or harms for additional blood loss of 1000 mL or more (RR 0.76, 95% CI 0.43 to 1.34, moderate-certainty, 3 trials, 1814 participants, one study reported zero events), and maternal mortality or severe morbidity (RR 1.09, 95% CI 0.35 to 3.39, moderate-certainty). Misoprostol plus oxytocin increases the incidence of fever (4 trials, 1866 participants, RR 3.07, 95% CI 2.62 to 3.61, high-certainty), and vomiting (2 trials, 1482 participants, RR 1.85, 95% CI 1.16 to 2.95, high-certainty) compared with oxytocin alone. For all outcomes of interest, the available evidence on the misoprostol versus Syntometrine® plus oxytocin combination was of very low-certainty and these effects remain unclear. Although network meta-analysis was not performed, we were able to compare the misoprostol plus oxytocin combination with misoprostol alone through the common comparator of oxytocin. This indirect comparison suggests that the misoprostol plus oxytocin combination probably reduces the risk of blood transfusion (RR 0.65, 95% CI 0.42 to 0.99, moderate-certainty) and may reduce the risk of additional blood loss of 1000 mL or more (RR 0.30, 95% CI 0.10 to 0.89, low-certainty) compared with misoprostol alone. The combination makes little or no difference to vomiting (RR 0.75, 95% CI 0.35 to 1.59, high-certainty) compared with misoprostol alone. Misoprostol plus oxytocin compared to misoprostol alone are compatible with a wide range of treatment effects for additional blood loss of 500 mL or more (RR 0.51, 95% CI 0.20 to 1.26, low-certainty), maternal mortality or severe morbidity (RR 0.55, 95% CI 0.07 to 4.24, low-certainty), use of additional uterotonics (RR 0.76, 95% CI 0.33 to 1.73, low-certainty), and fever (RR 0.90, 95% CI 0.17 to 4.77, low-certainty). AUTHORS' CONCLUSIONS: The available evidence suggests that oxytocin used as first-line treatment of PPH probably is more effective than misoprostol with less side-effects. Adding misoprostol to the conventional treatment of oxytocin probably makes little or no difference to effectiveness outcomes, and is also associated with more side-effects. The evidence for most uterotonic agents used as first-line treatment of PPH is limited, with no evidence found for commonly used agents, such as injectable prostaglandins, ergometrine, and Syntometrine®.

Ethics and ego dissolution: the case of psilocybin.

Despite the fact that psychedelics were proscribed from medical research half a century ago, recent, early-phase trials on psychedelics have suggested that they bring novel benefits to patients in the treatment of several mental and substance use disorders. When beneficial, the psychedelic experience is characterized by features unlike those of other psychiatric and medical treatments. These include senses of losing self-importance, ineffable knowledge, feelings of unity and connection with others and encountering 'deep' reality or God. In addition to symptom relief, psychedelic experiences often lead to significant changes in a patient's personality and worldview. Focusing on the case of psilocybin, we argue that the peculiar features of psychedelics pose certain novel risks, which warrant an enhanced informed consent process-one that is more comprehensive than what may be typical for other psychiatric medications. We highlight key issues that should be focused on during the consent process and suggest discussion prompts for enhanced consent in psychedelic psychiatry. Finally, we respond to potential objections before concluding with a discussion of ethical considerations that will arise as psychedelics proceed from highly controlled research environments into mainstream clinical psychiatry.

An Efficient Molecular Simulation Methodology for Chemical Reaction Equilibria in Electrolyte Solutions: Application to CO2 Reactive Absorption.

We develop a computationally efficient molecular-based simulation algorithm for chemical reaction equilibria in liquids containing neutral and ionic species, which is based on the combination of classical force field and ab initio calculations and permits calculations involving very small species concentrations. We show its application to the reactive absorption of CO2 in aqueous monoethanolamine (MEA) solvent as a benchmark case, the first time that a quantitatively accurate predictive approach requiring no experimental data has been successfully applied to calculate all solution species concentrations for this system, including the partial pressure of CO2 above the solution. The Reaction Ensemble Monte Carlo (REMC) algorithm, the only other generally applicable approach, requires special system-dependent Monte Carlo enhancements for its implementation, and to detect species with very small concentrations requires long simulation times and/or large system sizes. In contrast, the proposed algorithm can be straightforwardly implemented for systems of any molecular complexity using a standard Molecular Dynamics (MD) simulation package capable of calculating free energy changes and can calculate small species concentrations with normal simulation times and system sizes. In addition, the inherent parallelization capability of MD (which is problematic for MC-based approaches) enables the algorithm's computationally efficient implementation. The H2O-MEA-CO2 benchmark system has been the subject of many previous studies based on macroscopic thermodynamic modeling, which primarily involves fitting their parameters (of which reaction p K values are the most important) to experimental data measurements. To make contact with such approaches, we show the translation of the molecular-based quantities to the direct prediction of these parameters and calculate reaction equilibrium in the framework of a Henry Law-based chemical potential model. We consider both the ideal solution form and its extension using the Davies equation for the species activity coefficients. We study a range of temperatures and CO2 solution loadings in a 30 wt % MEA solution and incorporate an uncertainty analysis in our methodology. We find that the uncertainties of the simulated solution species compositions are comparable to those of the available experimental data. We report predictions of minor species compositions of very small magnitude, for which experimental measurements are typically extremely challenging.

Notes on substantance in orthodox theory: a reply to Badano.

Gabriele Badano offers three criticisms of my challenge to the orthodox family of theories of legitimacy in bioethics. First, I assumed an 'oversimplified version of the orthodoxy'. Second, I failed to appreciate its domain of application. Third, I only addressed the ways in which orthodox theorists incorporate substance as an 'afterthought'-and, even then, only by rehashing Gopal Sreenivasan's argument. Here, I respond to each, taking up the first and third before ending with reflections on the second. The first underestimates the insight that criticism of the simplified version provides to that of the more complex relatives. The third misunderstands the relationship between my view and Sreenivasan's and neglects an entire argument of my paper. The second fails in light of these two, but raises interesting questions about how the method I suggest might be extended to other domains.

Double Versus Single Tendon Transfers to Improve Shoulder Function in Brachial Plexus Birth Palsy.

BACKGROUND: In children with brachial plexus birth palsy (BPBP) undergoing tendon transfers to augment shoulder external rotation, it is unclear whether transfer of the latissimus dorsi with its combined latissimus dorsi and teres major (cLT) versus isolated teres major (iTM) tendon transfer yield different outcomes. METHODS: Records of patients with BPBP who underwent shoulder tendon transfers to augment external rotation were retrospectively reviewed. Transfer type (cLT or iTM) was considered indiscriminate by virtue of surgeon preference. Modified Mallet Scale (mMS) and Active Movement Scale scores were recorded. Patients with <12 months' follow-up, C7 or lower palsy, humeral osteotomy, shoulder procedure(s) within 8 months, microsurgery within 1 year, or recurrent glenohumeral subluxation confirmed by postoperative imaging were excluded. Matched cohorts were identified within each tendon transfer group to yield similar preoperative shoulder function and glenohumeral alignment status. Outcomes for all tendon transfers as well as differences between cLT and iTM cohorts were analyzed. RESULTS: Among 121 cLT and 34 iTM transfers, 49 cLT and 14 iTM met the inclusion criteria. Subsequent matching of cohorts yielded 28 patients (14 cLT and 14 iTM). Average age at time of transfer was 3.0±1.4 years. Follow-up averaged 4.1±3.1 years. There were no statistically significant preoperative differences between cohorts, thus matching criteria were validated. Regardless of tendon(s) transferred, mMS external rotation improved (2.2 to 3.5, P<0.001), whereas mMS internal rotation decreased (3.8 to 3.2, P<0.001). When comparing matched cohorts, cLT transfer produced a greater mMS external rotation improvement than iTM (2.1 vs. 1.5, respectively; P=0.025). Loss of midline function (defined as mMS external rotation <3) occurred in 5 (35.7%) cLT and 2 (14.3%) iTM patients. CONCLUSIONS: Both cLT or iTM transfer are effective at augmenting shoulder external rotation in children with C5-C6 BPBP. Furthermore, cLT transfers may yield a larger improvement in external rotation in certain patients. However, both techniques slightly decrease shoulder internal rotation. Given that more total cLT patients lost midline function among matched cohorts, iTM transfer may still be considered when limited midline function is a concern. LEVEL OF EVIDENCE: Level III.

Chemical potentials of alkaline earth metal halide aqueous electrolytes and solubility of their hydrates by molecular simulation: Application to CaCl2, antarcticite, and sinjarite.

We present a molecular-level simulation study of CaCl2 in water and crystalline hydrates formed by CaCl2 at ambient (298.15 K, 1 bar) conditions and at a high-temperature high-pressure state (365 K, 275 bars) typical of hydraulic fracturing conditions in natural-gas extraction, at which experimental properties are poorly characterized. We focus on simulations of chemical potentials in both solution and crystalline phases and on the salt solubility, the first time to our knowledge that such properties have been investigated by molecular simulation for divalent aqueous electrolytes. We first extend our osmotic ensemble Monte Carlo simulation technique [F. Moucka et al., J. Phys. Chem. B 115, 7849-7861 (2011)] to such solutions. We then describe and apply new methodology for the simulation of the chemical potentials of the experimentally observed crystalline hydrates at ambient conditions (antarcticite, CaCl2·6H2O) and at high-temperature conditions (sinjarite, CaCl2·2H2O). We implement our methodologies using for both phases the CaCl2 transferable force field (FF) based on simple point charge-extended water developed by Mamatkulov et al. [J. Chem. Phys. 138, 024505 (2013)], based on training sets involving single-ion and ion-pair low-concentration solution properties at near-ambient conditions. We find that simulations of the solution chemical potentials at high concentrations are somewhat problematic, exhibiting densities diverging from experimental values and accompanied by dramatically decreasing particle mobility. For the solid phases, the sinjarite crystalline lattice differs from experiment only slightly, whereas the simulations of antarcticite completely fail, due to instability of the crystalline lattice. The FF thus only successfully yields the sinjarite solubility, but its value m = 8.0(7) mol kg-1H2O lies well below the experimentally observed solubility range at 1 bar pressure of (12m, 15m) in the temperature interval (320 K, 400 K). We conclude that the used FF does not provide a good description of the experimental properties considered and suggest that improvement must take into account the crystalline properties.

NaCl nucleation from brine in seeded simulations: Sources of uncertainty in rate estimates.

This work reexamines seeded simulation results for NaCl nucleation from a supersaturated aqueous solution at 298.15 K and 1 bar pressure. We present a linear regression approach for analyzing seeded simulation data that provides both nucleation rates and uncertainty estimates. Our results show that rates obtained from seeded simulations rely critically on a precise driving force for the model system. The driving force vs. solute concentration curve need not exactly reproduce that of the real system, but it should accurately describe the thermodynamic properties of the model system. We also show that rate estimates depend strongly on the nucleus size metric. We show that the rate estimates systematically increase as more stringent local order parameters are used to count members of a cluster and provide tentative suggestions for appropriate clustering criteria.

Legitimacy in bioethics: challenging the orthodoxy.

Several prominent writers including Norman Daniels, James Sabin, Amy Gutmann, Dennis Thompson and Leonard Fleck advance a view of legitimacy according to which, roughly, policies are legitimate if and only if they result from democratic deliberation, which employs only public reasons that are publicised to stakeholders. Yet, the process described by this view contrasts with the actual processes involved in creating the Affordable Care Act (ACA) and in attempting to pass the Health Securities Act (HSA). Since the ACA seems to be legitimate, as the HSA would have been had it passed, there seem to be counterexamples to this view. In this essay, I clarify the concept of legitimacy as employed in bioethics discourse. I then use that clarification to develop these examples into a criticism of the orthodox view-that it implies that legitimacy requires counterintuitively large sacrifices of justice in cases where important advancement of healthcare rights depends on violations of publicity. Finally, I reply to three responses to this challenge: (1) that some revision to the orthodox view salvages its core commitments, (2) that its views of publicity and substantive considerations do not have the implications that I claim and (3) that arguments for it are strong enough to support even counterintuitive results. My arguments suggest a greater role for substantive considerations than the orthodox view allows.

Avalanche Safety Practices Among Backcountry Skiers and Snowboarders in Jackson Hole in 2016.

INTRODUCTION: Carrying standard safety gear (beacon, probe, and shovel), planning a route of descent, and recreating with companions can help to mitigate the risk of injury or death resulting from avalanches in the backcountry. The goal of this study was to identify factors associated with performance of these safety practices. METHODS: A convenience sample of backcountry skiers and snowboarders was surveyed in 2016 at the backcountry gates of Jackson Hole Mountain Resort. Each participant was surveyed on characteristics including skill level, sex, age, prior avalanche education, and residency in the Jackson Hole area. Safety practices were also measured against avalanche hazard forecasts. Correlations were assessed using Fisher's exact testing. RESULTS: A total of 334 participants were surveyed. Factors associated with carrying avalanche safety gear included higher expertise, being a resident of the Jackson Hole area, and prior avalanche education. Factors associated with having a planned route of descent included higher expertise and being a resident of the Jackson Hole area. Factors associated with recreating with companions included younger age and lower expertise. Sex had no association with any of the surveyed safety practices. Participants were less likely to carry avalanche safety gear on low avalanche hazard days. CONCLUSIONS: Certain individual characteristics of backcountry skiers and snowboarders are associated with increased frequency of adherence to recommended safety practices. These findings suggest that particular categories of backcountry recreationists may benefit from further avalanche safety education. The results of this study could help direct future educational efforts among backcountry recreationists.

Molecular simulation of caloric properties of fluids modelled by force fields with intramolecular contributions: Application to heat capacities.

The calculation of caloric properties such as heat capacity, Joule-Thomson coefficients, and the speed of sound by classical force-field-based molecular simulation methodology has received scant attention in the literature, particularly for systems composed of complex molecules whose force fields (FFs) are characterized by a combination of intramolecular and intermolecular terms. The calculation of a thermodynamic property for a system whose molecules are described by such a FF involves the calculation of the residual property prior to its addition to the corresponding ideal-gas property, the latter of which is separately calculated, either using thermochemical compilations or nowadays accurate quantum mechanical calculations. Although the simulation of a volumetric residual property proceeds by simply replacing the intermolecular FF in the rigid molecule case by the total (intramolecular plus intermolecular) FF, this is not the case for a caloric property. We describe the correct methodology required to perform such calculations and illustrate it in this paper for the case of the internal energy and the enthalpy and their corresponding molar heat capacities. We provide numerical results for cP, one of the most important caloric properties. We also consider approximations to the correct calculation procedure previously used in the literature and illustrate their consequences for the examples of the relatively simple molecule 2-propanol, CH3CH(OH)CH3, and for the more complex molecule monoethanolamine, HO(CH2)2NH2, an important fluid used in carbon capture.