Psychological, physical, and heat stress indicators prior to and after a 15-minute structural firefighting task

SIMPLE SUMMARY: Firefighters must endure extreme environments. Such exposure increases their body temperature, which can induce fatigue, reduce motivation, and impair their decision-making. This study set out to investigate the relationship between these factors. Nine firefighters were required to complete simulated firefighting tasks in a controlled structural fire for 15 min. Logical reasoning, speed and accuracy, memory recall, general motivation and fatigue, and physical and mental effort were recorded prior to, immediately after, and 20 min after the simulation. Results of this study identified that alongside a significant increase in firefighter tympanic membrane temperature post-task; (1) body weight loss was poorly correlated with post-task motivation and fatigue scores; (2) pre-task logical reasoning scores were predictive of change in tympanic membrane temperature. ABSTRACT: Firefighters work in strenuous conditions for prolonged periods wearing up to 20 kg of personal protective equipment. This often contributes to significant heat and cardiovascular strain. This study examined the relationships between psychological and physical measures taken prior to undertaking a 15 min firefighting task, and the occurrence of heat stress and high levels of fatigue following the task. Nine qualified firefighters completed a 15 min “live burn” scenario designed to mimic a fire started by a two-seater couch in a lounge room and completed simulated tasks throughout the duration. Logical reasoning, speed and accuracy, general motivation and fatigue, and physical and mental effort were recorded pre-scenario, and at 0- and 20-min post-scenario. General motivation and fatigue scores at 0- and 20-min post-scenario were highly correlated with each other (r(s) = 0.90; p = 0.001). The general motivation and fatigue scores, at 0- and 20-min post-scenario, were also strongly related to pre-task logic/reasoning test scores (Post 0 r(s) = −0.77, p = 0.016; Post 20 r(s) = −0.87, p = 0.002). Firefighters with lower logical reasoning and speed and accuracy scores were more susceptible to fatigue and impaired cognition when exposed to rises in core temperature and heat stress

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

Pool -boiling enhancement and liquid choking limits within and above a modulated porous -layer coating.

Modulated (periodically non-uniform thickness) porous-layer coatings, as an example of capillary artery-evaporator systems, are experimentally shown to enhance the pool-boiling critical heat flux nearly three times over that of a plain surface, while maintaining low surface superheats. This enhancement is examined experimentally and discussed theoretically. This work marks the first such study on the effect of modulation of a porous-layer coating on pool boiling. The fabrication of the modulated porous-layer coating consisting of sintered, monosized, spherical copper particles is described. Measurements of the heat flux versus surface superheat, during the wetted-surface regime and up to the critical heat flux, are presented for plain surfaces and surfaces with uniform and modulated porous-layer coating. The modulation separates the liquid and vapor phases, thus reducing the liquid-vapor counterflow resistance adjacent to the surface. Theories are suggested for two independent mechanisms that are capable of causing the liquid-choking that leads to the critical heat flux. The liquid-choking limit predicted to occur first, with increasing surface heat flux, is considered to correspond to the critical heat flux experienced by the surface. The Zuber hydrodynamic theory for the critical heat flux is modified to account for the effect of the coating modulation-wavelength on the development of a stable vapor layer above the coated surface, effectively choking the liquid down-flow towards the surface (above the coating). The resulting hydrodynamic model relates this second liquid-choking limit to the inverse of the square root of the modulation wavelength. A finite-volume model of the transport in the porous-layer coating is used to predict the heat flux versus surface superheat. The second liquid-choking limit is predicted by this model and occurs within the porous-layer coating when the viscous drag surpasses the available capillary pumping. The predicted wetted-surface regime and the two liquid-choking limits are compared with the measurements and good agreement is found. All of the tested surfaces are predicted to have hydrodynamically determined heat fluxes. The theories are then used to discuss the optimization of the enhancement and suggest that completely separated liquid and vapor flow paths can result in substantial further enhancement.Ph.D.Applied SciencesMechanical engineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/132824/2/9990927.pd

The Character Strengths of Australian Army Personnel

The overarching aim of this dissertation was to delineate the character strengths of Australian Army personnel. Using a short-form survey incorporating Peterson and Seligman's (2004) taxonomy of 24 character strengths, four empirical studies were conducted containing samples of Australian Army officers, Special Forces (SF) personnel, and enlisted soldiers. Across all studies, respondents self-ranked the strengths of team worker, integrity, and to a lesser extent, good judgment as characteristic of themselves and/or good leaders. In two prospective studies, enlisted soldiers who applied for the SF (Ns = 115, 95) ranked themselves on 24 character strengths at the start of the selection process. In Study One, successful applicants gave a top-four rank to the strengths of team worker, integrity, and persistence significantly more often than unsuccessful applicants. Unsuccessful applicants who did not include any of these three strengths in their top four ranks all failed to complete the selection process. In Study Two, successful applicants assigned team worker a top-four rank significantly more often than unsuccessful applicants. In Study Three, experienced SF operators (N = 214) assigned team worker a top-four rank significantly more often than support troops in the same unit (N = 123). In contrast, the SF operators gave a top-four rank to integrity significantly less often than the support troops. In Study Four, Australian Army officers (N = 171) were asked to self-rank their character strengths, nominate strengths of effective leaders, and nominate strengths desirable in team members. Officers significantly self-ranked the strengths of integrity, leadership, good judgment, trustworthiness, and team worker. Additional strengths, especially wisdom, were associated with effective leaders, while officers desired the strengths of humour, initiative, and enthusiasm in team members. Findings are discussed in regards to individual, team, and organisational performance in and beyond the military

Re-examining the Home Disadvantage in Professional Ice Hockey

Occurrence of the home disadvantage in professional ice hockey was examined by analyzing shootout data from 2005 through 2008. Results indicated that teams involved in shootouts playing at their home arenas did not lose significantly more games at home than on the road. Results did not support the hypotheses that emphasize the roles of physical contact and diffusion of responsibility in accounting for past failures to find the home disadvantage in professional ice hockey