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Human decision-making is prone to biases and the use of heuristics that can result in making logical errors and erroneous causal connections, which were evident during COVID-19 policy developments and potentially contributed to the inadequate and costly responses to COVID-19. There are decision-making frameworks and tools that can improve organisational decision-making. It is currently unknown as to what extent public health administrations have been using these structured organisational-level decision-making processes to counter decision-making biases. Current reviews of COVID-19 policies could examine not just the content of policy decisions but also how decisions were made. We recommend that understanding whether these decision-making processes have been used in public health administration is key to policy reform and learning from the COVID-19 pandemic. This is a research and practice gap that has significant implications for a wide range of public health policy areas and potentially could have made a profound difference in COVID-19-related policy responses.

Background: Previous research on employee well-being for those who have experienced social and economic disadvantage and those with previous or existing mental health conditions has focused mainly on programmatic interventions. The purpose of this research was to examine how organisational structures and processes (such as policies and culture) influence well-being of employees from these types of backgrounds., Methods: A case study ethnographic approach which included in-depth qualitative analysis of 93 semi-structured interviews of employees, staff, and managers, together with participant observation of four social enterprises employing young people., Results: The data revealed that young people were provided a combination of training, varied work tasks, psychosocial support, and encouragement to cultivate relationships among peers and management staff. This was enabled through the following elements: structure and space; funding, finance and industry orientation; organisational culture; policy and process; and fostering local service networks.. The findings further illustrate how organisational structures at these workplaces promoted an inclusive workplace environment in which participants self-reported a decrease in anxiety and depression, increased self-esteem, increased self-confidence and increased physical activity., Conclusions: Replicating these types of organisational structures, processes, and culture requires consideration of complex systems perspectives on implementation fidelity which has implications for policy, practice and future research., (© 2022. The Author(s).)

Introduction: Fighter aircraft pilots are exposed to repetitive headward acceleration (+Gz) during air combat maneuvering. The objective of this study was to compare physiologic responses and the calculated +Gz tolerances of multiple successive +Gz exposures with the responses of the first +Gz exposure., Methods: There were 13 subjects who performed simulated air combat maneuvering (SACM) profiles composed of 10 rapid-onset rate +Gz cycles with different combinations of short- or long-duration +Gz plateaus (8 or 20 s) and +Gz pauses (1 or 15 s). +Gz, plateaus were individually set at levels inducing strong physiologic responses while the +Gz pause was set at 1.4 Gz. Head-level systolic pressure, ear opacity, and vision quality were measured., Results: The nadirs of head-level systolic pressure, ear opacity, and visual quality during each +Gz plateau were higher in subsequent cycles compared to the first +Gz cycle. There was an average increase in calculated +Gz tolerance of 0.35 +/- 0.21 Gz following the first +Gz cycle. SACMs with short +Gz pauses produced greater increases in +Gz tolerance than SACMs with long +Gz pauses., Discussion: Cardiovascular and visual responses were improved over the course of successive +Gz cycles, indicating that the risk of +Gz-induced loss of consciousness was not increased beyond the first +Gz cycle. The increase in +Gz tolerance beginning with the second cycle is attributed to a carryover of compensatory responses, primarily vasoconstriction, with possible contribution from greater venous return and baroreflex enhancement.

Introduction: The Canadian Forces has initiated a multiple study project to optimize circadian phase changes using appropriately timed phototherapy and/or ingestion of melatonin for those personnel on long-range deployments and shift workers. The work reported here compared four phototherapeutic devices for efficacy in effecting circadian phase delays., Methods: In a partially counterbalanced treatment order, 14 subjects (7 men and 7 women), ages 18-51 yr, participated in 5 weekly experimental sessions of phototherapy with 4 different phototherapy devices (light tower, light visor, Litebook, LED spectacles) and a no-phototherapy control. Phototherapy was applied from 24:00 to 02:00 on night. (1) Dim light melatonin onset (DLMO) was assessed on night 1 and night. (2) Subjects were tested for psychomotor performance (serial reaction time, logical reasoning, and serial subtraction tasks) and completed the Stanford Sleepiness Scale on night 1 at 19:00, 23:00, 01:00, 02:00, and 03:00. After phototherapy, subjects completed a phototherapy side-effects questionnaire., Results: All phototherapy devices produced melatonin suppression and significant phase delays. Sleepiness was significantly decreased with the light tower, the light visor, and the Litebook. Task performance was only slightly improved with phototherapy. The LED spectacles and light visor caused greater subjective performance impairment, more difficulty viewing the computer monitor and reading printed text than the light tower or the Litebook. The light visor, the Litebook, and the LED spectacles caused more eye discomfort than the light tower., Conclusions: The light tower was the best device, producing melatonin suppression and circadian phase change while relatively free of side effects.

Introduction: Although Canadian Forces (CF) efforts directed at developing new G-protection strategies have often raised the question of potential benefits of physical conditioning (PC) on G tolerance (GT), a fatality in a CF fighter aircraft accident, in which it was suggested the pilot may have had 'sub-optimal GT,' sparked renewed interest in this topic., Methods: A two-part review was conducted: 1) a survey of the literature on the effects of PC on GT; and 2) a determination of further research required to resolve uncertainties on the subject., Results: Five key themes surfaced: 1) GT as a concept is complex, and has different connotations for different users; 2) the term 'PC' likewise has a variety of meanings, and precise definitions are necessary to compare research results; 3) in examining the relationship between PC and GT, the roles of strength training, muscle fatigue, and aerobic fitness are not as clear as some studies seem to suggest; 4) in designing PC programs to enhance GT, issues such as palatability, efficacy, and intended target population must be addressed for the program to be operationally useful; and 5) there is a requirement for investigations that have controlled important influences such as intercurrent +Gz-stress exposure, proficiency in performing the anti-G straining maneuver, and the wide inter- and intra-individual variation for PC and GT measurements., Discussion: The effects of PC on GT are not well established. Further research with more robust experimental designs and/or analyses than those used to date must be conducted (on new or existing data) to clarify this relationship. Conducting such work with sound experimental design and controls is more complex and time-consuming than some may appreciate.

Hypothesis: This study tested the hypothesis that respiratory muscle fatigue occurs during a simulated air combat maneuver (SACM) centrifuge profile., Methods: Six subjects (four males, two females) were exposed to a SACM consisting of alternating +4 Gz to +7 Gz plateaus until volitional fatigue. Electrical activities of the diaphragm, scalene, intercostal and external oblique muscles were monitored along with esophageal pressure and ventilation., Results: SACM times averaged 358 +/- 115 s. The mean frequency of the electromyographic signal of the diaphragm and scalenes during inspiration, and the intercostals during the static expiratory portion of the anti-G straining maneuver (AGSM), decreased significantly (p < 0.05) over the course of the SACM by about 9%, 10% and 4%, respectively, indicating muscle fatigue. Esophageal pressure (PES) during the straining portion of the AGSM decreased significantly from 72 +/- 20 to 66 +/- 21 mmHg (mean +/- SD). Ventilation increased significantly both at +4 Gz and +7 Gz (32 +/- 16 L.min-1 to 56 +/- 19 L.min-1 at +4 Gz and 27 +/- 5 to 35 +/- 9 L.min-1 at +7 Gz) over time. PES during a maximal AGSM at +1.4 Gz (baseline) was decreased post- vs. pre-SACM (p = 0.0575). PES exerted during a maximal static inspiratory maneuver at residual lung volume was not changed after the SACM. Inspiratory work increased significantly during the SACM. The elastance of the respiratory system did not change during the SACM, but it was significantly increased when tested after the SACM., Conclusion: Increased inspiratory work, decreased pressure generation during a maximal AGSM and EMG frequency shifts suggest respiratory muscle fatigue coincides with the termination of SACM.

Electronic control of the G-valve and pressure breathing regulator is being implemented in some advanced life support systems used in aircrew protection. This technological improvement, however, has not reached its full potential in the research environment. A computer-controlled life support system interface providing programmable schedules for G-suit inflation and positive pressure breathing during +Gz (PBG) was developed. Output pressures from a G-valve and pressure breathing regulator (Carleton Technologies) were controlled by a Macintosh computer running LabVIEW software. Required pressures were determined as functions of single or multiple control inputs (i.e. +Gz level, a pressure signal, time, etc.). Subject safety was ensured via hardware limitations and status checks incorporated into the software. Experiments conducted at +1 Gz and at various +Gz levels evaluated the computer software-life support hardware interface. Open-loop algorithms allowed independent control of multiple regulators using simple (single input) and complex (multiple input with adaptive loop) control structures. The system provided accurate and reproducible G-suit and mask pressures. Time of inflation, peak pressure attained, and deflation rate were effectively controlled at all +Gz levels. The ability to alter the pressure schedules independent of +Gz or time allowed comprehensive control over all parameters necessary to conduct acceleration research involving advanced life support systems.

This study tested the hypothesis that repeated exposure to high levels of +Gz acceleration, in conjunction with repeated execution of an Anti-G Straining Maneuver (AGSM), causes central fatigue, presumably by impairing central nervous system (CNS) function. We speculated that central fatigue would impair the ability to recruit sufficient musculature at the intensity required to perform an adequate anti-G straining maneuver. Central fatigue was evaluated by measuring maximal force generation and surface electromyographic activity of leg extensor muscles before, during, and immediately upon termination of an SACM, and comparing these values to those obtained when the muscles were electrically stimulated during maximal voluntary contractions (MVCs). We assumed that any observed increase in force generation during the MVCs, caused by the stimulation, would indicate central fatigue. G-tolerance time was 230 +/- 172 s. Hypoxia was induced by the SACM as the arterial oxygen saturation decreased significantly from 97% to 90%. In spite of this hypoxia, there was no significant change in MVC force when the pre- and post-SACM values were compared. Electrical stimulation during the MVC's did not cause an increase in force generation. The average forces generated during the +7 Gz phase of the SACM were only about 35% of MVC force. This force value did not change significantly during the SACM. The results indicate that the inability to continue to perform the AGSM during an SACM is not likely due to central fatigue or to fatigue of the large skeletal muscle groups we have examined.(ABSTRACT TRUNCATED AT 250 WORDS)

Pilots exposed to high levels of headward (+Gz) acceleration must perform voluntary muscle contractions in order to maintain head-level arterial pressure. To study the possibility that muscular fatigue can limit human +Gz duration tolerance, electromyographic (EMG) activity and EMG indices of muscular fatigue were measured during a simulated air combat maneuvering (SACM) centrifuge profile. Eight experienced male volunteers were exposed to a +4-7 Gz centrifuge profile until volitional fatigue. Electrical activity (EMG) was recorded from 7 muscles: biceps brachii (BB), latissimus dorsi (LD), pectoralis major (PM), rectus abdominis (RA), vastus lateralis (VL), biceps femoris (BF) and gastrocnemius (GN). EMG and force during isometric contractions of the same muscles were also recorded at 1 G. Root mean square (RMS) and mean power frequency (MPF) were calculated for each second of EMG data. G-tolerance time averaged 256 +/- 33 s (mean +/- SD). RMS activity was expressed relative to activity during a maximal muscle contraction. The mean values (%) for each muscle during the 7 Gz plateaux were: RA, 30.8; BB, 26.4; LD, 44.0; PM, 48.5; VL, 43.4; BF, 31.4; GN, 39.3. The estimated level of contraction relative to a MVC (%) was: RA, 36.6; BB, 30.5; LD, 43.9 and PM, 61.4. There was no significant difference between contraction levels for any of the muscles studied. RMS activity did not increase over time and MPF decreased significantly only in BF and LD, however, these decreases were small. EMG activity and estimated contraction intensities were considered to be low to moderate. These results suggest that it is unlikely that fatigue in the muscles studied would limit G-tolerance time.

The increase in blood pressure provided by the standard AGSM is caused by both the contraction of the muscles of the lower body and by an increased intrathoracic pressure due to a respiratory straining (Valsalva) maneuver. This study examined the relative effectiveness and fatigability of the two components at +1 Gz and during +Gz acceleration in a human centrifuge. Brachial arterial pressure was recorded from a pressure-tip transducer in six subjects performing isometric leg presses only and on a separate occasion while performing respiratory straining only. Measurements were made over a range of intensities for the leg press contractions and Valsalva maneuvers and were conducted at +1 Gz and during slow and rapid onset runs up to +5 Gz in a human centrifuge. Blood pressure was also recorded during pulsing or intermittent contractions of the legs. We found it difficult to completely separate the blood pressure response to the leg press component from that of the respiratory straining alone component, since a moderate respiratory straining maneuver usually accompanied forceful contractions of the legs. We conclude, however, that a major portion of the elevation in blood pressure caused by the AGSM can be attributed to contraction of the muscles of the lower body and that this component is less fatiguing than the respiratory straining component. At +1 Gz a pulsing isometric contraction of the legs was no more effective in elevating blood pressure than a constant isometric contraction over the same duration.

Positive pressure breathing during +Gz (PBG) and anti-G straining maneuvers (AGSM) each improve +Gz tolerance by increasing blood pressure through increases in intra-thoracic pressure, but the maximal intra-thoracic pressure from their combined effect is not known. Six subjects performed the following: 1) maximal AGSM at +1 Gz; 2) assisted PBG (constant 60 mm Hg) at +Gz; 3) submaximal AGSM at +Gz (enough to maintain peripheral vision); 4) maximal AGSM at +Gz; and 5) combined PBG and maximal AGSM at +Gz. They wore TLSS mask/helmet ensemble, CSU-15/P G-suit, and TLSS-style jerkin. Intra-thoracic pressure was measured with a catheter-tip pressure transducer in the esophagus (Pes). The change in gastric pressure was also measured (delta Pga). For both Pes and delta Pga, there were no significant differences among experimental conditions (1), (4) and (5), as above. Group mean Pes and delta Pga in these three conditions were 139 and 197 mm Hg, respectively. The similar results between maximal AGSM, and maximal AGSM and PBG are explained by limited support from the thoracic counter-pressure garment, and the characteristics of the respiratory system.

A base of empirical data for developing optimal pressure breathing during +Gz (PBG) schedules is lacking. Relaxed +Gz-intensity tolerance with PBG was measured during gradual +Gz-onset rate centrifuge profiles using standard lightbar criteria. Constant PBG levels ranging from 18-73 mm Hg were randomly assigned. G-suit pressure followed the standard or an increased inflation schedule. Nine subjects wore a jerkin, CSU-15/P G-suit, and TLSS helmet and mask. With mean mask cavity pressures of 0, 18, 38, 60, and 73 mm Hg, corresponding +Gz-tolerances (mean +/- S.E.M.) were: 5.3 +/- 0.2, 5.8 +/- 0.1, 6.6 +/- 0.2, 7.3 +/- 0.3, and 7.5 +/- 0.3 Gz (linear correlation, r = 0.994). Increased G-suit pressure did not change the +Gz-tolerance improvement with PBG. The inverse of individual subject regression slopes ranged from 22.6 to 58.1 mm Hg/+Gz. Considering additional factors and adequate +Gz protection for all subjects while relaxed, the proposed schedule would apply 42 mm Hg PBG/+Gz beginning at +3.3 Gz with a maximum pressure of at least 73 mm Hg.

Muscle glycogen and muscle and blood lactate were evaluated before and after a +4.0/7.0 Gz simulated air combat maneuvering (SACM) protocol in the human centrifuge. The subjects were eight healthy males, ages 25-43 years. Muscle glycogen and lactate were determined from biopsies of m. vastus lateralis in six subjects and whole blood lactate was analyzed in finger-tip blood samples from eight subjects. G-tolerance time was 256 +/- 33 s (Mean +/- S.E.M.). The decrease in glycogen concentration averaged 81 +/- 36 mmol.kg-1 dry wt (p = 0.07). The rate of glycogen utilization was low, averaging 0.4 +/- 0.1 mmol.kg-1.s-1. Muscle lactate increased significantly from 28 +/- 2 mmol.kg-1 dry wt pre-SACM to 51 +/- 4 mmol.kg-1 post-SACM. Post-SACM blood lactate was 4.2 +/- 0.3 mmol.L-1. Neither final blood nor muscle lactate values nor the difference between pre- and post-SACM muscle lactate concentrations were related to G-tolerance time. It was concluded that glycogen availability in m. vastus lateralis is not a limiting factor during exposure to headward acceleration of this type and duration. The lactate values, while high, cannot fully explain the muscular fatigue occurring during centrifuge exposures of the type used here. Therefore, the suggestion by others that anaerobic energy metabolism in skeletal muscles is the crucial factor limiting the ability to resist fatigue during exposure SACM is not supported and is likely an oversimplification of a much more complex problem.

This investigation studied oxyhemoglobin saturation (SaO2) and cardiovascular indices after rapid decompression (RD). Before RD, fractional inspired O2 concentration (FIO2) simulated the range of product gas from molecular sieve O2 generating systems (MSOGS). Four subjects breathed 1.0-0.80 FIO2 at 6,858 m. After decompression to 18,288 m, the subject received 1.0 FIO2 at a positive pressure of 70 mm Hg for 3 min. There were no incidents of severe hypoxia. The mean SaO2 was 98.0% before RD. After RD, SaO2 was maintained at the pre-RD level for 8 s, decreased rapidly over the next 10 s, and over the rest of the 1st min decreased more gradually to reach approximately 82%. Varying FIO2 before RD had no effect on the alteration in SaO2, heart rate, stroke index, and blood pressure after RD. The MSOGS O2 product range offers adequate protection against hypoxia during RD to 18,288 m.