Acridine photocatalysis enables tricomponent direct decarboxylative amine construction.

Amines are centrally important motifs in medicinal chemistry and biochemistry, and indispensable intermediates and linchpins in organic synthesis. Despite their cross-disciplinary prominence, synthetic access to amine continues to rely on two-electron approaches based on reductions and additions of organometallic reagents, limiting their accessible chemical space and necessitating stepwise preassembly of synthetic precursors. We report herein a homogeneous photocatalytic tricomponent decarboxylative radical-mediated amine construction that enables modular access to α-branched secondary amines directly from the broad and structurally diverse chemical space of carboxylic acids in a tricomponent reaction with aldehydes and aromatic amines. Our studies reveal the key role of acridine photocatalysis acting in concert with copper and Brønsted acid catalytic processes in facilitating the previously inaccessible homogeneous photocatalytic reaction and provide a streamlined segue to a wide range of amines and nonproteinogenic α-amino acids.

Kinetically-driven reactivity of sulfinylamines enables direct conversion of carboxylic acids to sulfinamides.

Sulfinamides are some of the most centrally important four-valent sulfur compounds that serve as critical entry points to an array of emergent medicinal functional groups, molecular tools for bioconjugation, and synthetic intermediates including sulfoximines, sulfonimidamides, and sulfonimidoyl halides, as well as a wide range of other S(iv) and S(vi) functionalities. Yet, the accessible chemical space of sulfinamides remains limited, and the approaches to sulfinamides are largely confined to two-electron nucleophilic substitution reactions. We report herein a direct radical-mediated decarboxylative sulfinamidation that for the first time enables access to sulfinamides from the broad and structurally diverse chemical space of carboxylic acids. Our studies show that the formation of sulfinamides prevails despite the inherent thermodynamic preference for the radical addition to the nitrogen atom, while a machine learning-derived model facilitates prediction of the reaction efficiency based on computationally generated descriptors of the underlying radical reactivity.

Panic disorder in military aviators: a retrospective study of prevalence.

INTRODUCTION: The occurrence of panic disorder (PD) among military pilots and navigators poses questions with respect to medical care and waiver policy, but the prevalence of such disorders is unclear. We studied the epidemiology of PD in a USAF aircrew population. METHODS: Occurrence of PD during the period 2001-2008 was determined using the USAF Aeromedical Information Management Waiver Tracking System, a database containing medical disqualifications and waivers for the entire population of both qualified and disqualified (grounded) USAF aviators. RESULTS: The mean annual USAF pilot and navigator population averaged 17,727 during the study period. The database yielded nine cases labeled as PD. After records review by two experienced aeromedical psychiatrists, only three of the nine cases met diagnostic criteria for PD. Estimated annual PD prevalence was 0.002% (2/100,000) in USAF pilots and navigators. Annual prevalence of PD was 2.7% in the general U.S. population 18 yrS. of age and older and 2.4% in a group of manager/professionals. Odds ratios were 1228 (55/27,269) and 1089 (49/24,175) for the general population and manager/professionals, respectively. DISCUSSION: One of three individuals with PD received a waiver to resume flying after successful treatment. Five of the six cases not meeting criteria for PD (but suffering from varying degrees of situational and/or stress related anxiety) were flying with waivers. The negligible annual PD prevalence in USAF pilots and navigators likely reflects lower aircrew vulnerability to PD because of selection and training processes and does not pose a disease burden upon force strength.

Optical filter effects on night vision goggle acuity and preservation of dark adaptation.

INTRODUCTION: The high output of night vision goggles (NVGs) can cause a loss of dark adaptation, resulting in suboptimal unaided vision. Optical filters have been designed to mitigate this problem by changing the overall output characteristics of the NVGs. METHODS: Several aspects of visual performance related to NVG use were studied in a repeated measures design, filters versus no filters. NVG acuity was assessed using a 25% contrast chart, while preservation of dark adaptation after NVG use was measured with a scotopic sensitivity tester (SST) and a low luminance acuity chart. Testing was accomplished at two light levels, roughly corresponding to starlight and quarter moon conditions. RESULTS: Use of the filters resulted in a statistically significant loss of acuity of about a 1/2 line (approximately 2.5 letters) at both light levels. The second part of the study identified a 47% improvement in preservation of dark adaptation under simulated starlight conditions and a 31% improvement under simulated quarter moon conditions with filter use; however, only the starlight finding was statistically significant. No significant differences in performance were seen with the low luminance chart. DISCUSSION: Despite a small loss of visual acuity with filter use, the improvement in retention of dark adaptation may be beneficial in certain operational environments. Aviators, airmen, and commanders should evaluate how the potential for slightly poorer visual acuity and improved recovery of dark adapted vision relates to their mission specific requirements prior to implementing use of NVG filters.

Major depressive disorder in military aviators: a retrospective study of prevalence.

INTRODUCTION: The occurrence of major depressive disorder (MDD) among military pilots and navigators poses questions with respect to medical care and waiver policy, but the prevalence of such disorders is unclear. We studied the epidemiology of MDD in a USAF aircrew population. METHODS: The occurrence of MDD was determined for the period 2001-2006 using the USAF Aeromedical Information Management Waiver Tracking System, which records medical disqualifications and waivers for the entire population of both qualified and disqualified (grounded) USAF aviators. RESULTS: The mean annual population of USAF pilots and navigators averaged 17,781 during the study period. The database yielded 51 cases of MDD, of which 8 were recurrent and 43 were single episodes. All of the recurrent cases were disqualified, while 18 of the single-episode cases (42%) received a flying waiver after being asymptomatic without medications for at least 6 mo. Estimated annual MDD prevalence was 0.06% for the study population. In comparison, the annual prevalence of MDD is 6.7% in the general U.S. population, 2.8% among groups of executives and 4.1% among professionals. Odds ratios were 128 (68,238), 51 (27,96), and 76 (41,142) for the general population, executives, and professionals, respectively. DISCUSSION: Annual MDD prevalence among USAF pilots and navigators was significantly lower than that of the general U.S. population. The difference may reflect lower aircrew vulnerability to depression because of selection and training processes or lower rates of self-report and treatment due to feared aeromedical and/or career consequences.

Recurrent error pathways in HFACS data: analysis of 95 mishaps with remotely piloted aircraft.

BACKGROUND: According to Reason's model of accident causation, mishaps tend to fall into recurrent patterns. This model is the foundation for the Human Factors Analysis and Classification System (HFACS), which is now widely used in aviation accident analysis. The purpose of this study was to determine if it was possible to use HFACS to identify recurrent error pathways within an existing mishap database. METHODS: All MQ-1 Predator remotely piloted aircraft (RPA) mishaps and safety incidents reported to the Air Force Safety Center during fiscal years 1997-2005 were evaluated and entered into a mishap database (N = 95). An exploratory principal component analysis (PCA) was used to assess the factorial structure within the set of crewmember-related mishaps (N = 48). The results of the PCA were used to define recurrent pathways from latent to active failure and hence mishaps. A tree diagram was subsequently created to quantitatively assess the associations identified in the PCA. RESULTS: Four factors were identified, each consisting of one of the HFACS categories of active failure and one or more categories of latent failure. Two additional factors were identified, consisting of fatigue and motivational latent failures. Based on analysis of the tree diagram, the majority of mishaps were caused by latent failures involving organizational factors and the technological environment. CONCLUSIONS: It was possible to identify four recurrent error pathways associated with the four types of HFACS active failures within this sample of RPA mishaps. Two of these error pathways, accounting for 57% of crewmember-related mishaps, were consistent with situation awareness errors associated with perception of the environment.

Post-Traumatic Stress Symptoms in United States Air Force Aeromedical Evacuation Nurses and Technicians.

Critical Care Air Transport Teams (CCATT) are specialized military medical personnel who provide high-acuity care in an aeromedical environment. The rate of post-traumatic stress disorder (PTSD) symptoms was assessed in CCATT personnel and their rates were compared to general aeromedical evacuation (AE) personnel. As part of a computer-based occupational stress survey, 188 crew members (138 AE nurses and technicians, 50 CCATT nurses and respiratory therapists) completed the PTSD Checklist - Military Version. A categorical MEET/DOES NOT MEET CRITERIA variable was created, and a Fisher's exact test was computed to identify differences between groups. Contingency table analyses were used to assess associations between demographic and occupational variables with meeting criteria. χ2 or Fisher's exact test results, relative risks, and 95% confidence intervals were obtained, with 4.35% of AE and 14.00% of CCATT crew members meeting PTSD symptom criteria. The CCATT crew members were 3.22 times (95% confidence interval = 1.14-9.12) more likely to meet symptom criteria than AE, and for CCATT meeting criteria, the most commonly endorsed symptoms were arousal and avoidance. The demographic and occupational factors assessed in this study were not associated with meeting PTSD symptom criteria. Current findings are discussed in relation to current research on post-traumatic stress in ground-based critical care personnel.

Fatigue in military aviation shift workers: survey results for selected occupational groups.

BACKGROUND: Shift workers are particularly vulnerable to increased sleepiness, chronic fatigue, and decreased performance, which can adversely impact productivity and safety in military flight operations. This study examined the association of specific risk factors including work context and shift system details (squadron: remotely piloted aircraft [RPAI vs. manned aircraft [MA]), work/rest guidelines (career field: crewmember vs. maintainer), and participation in deployed operations (environment: home base vs. deployed) on subjective fatigue using standardized and validated fatigue questionnaires. METHODS: A cross-sectional survey of 172 U.S. Air Force (USAF) personnel was conducted from October 2004 to May 2005. The study sample was recruited from four different USAF occupational groups involved in some form of shift work to include irregular, rotational, or fixed shifts. RESULTS: Participants reported a mean (SD) of 6.6 (1.8) hours of sleep per day with no differences by squadron, career field, or environment. Mean daily sleep did not correlate with scores on the fatigue questionnaires. Mean scores on the fatigue questionnaires were associated with squadron (mean fatigue score: RPA > MA), but not with career field or environment. There were no significant interaction effects, nor were there significant effects based on the covariates age, gender, and rank. CONCLUSION: Work context, shift system details, or both appeared to best explain the observed differences in fatigue between USAF shift worker populations. Crewmember work/rest guidelines did not appear to be useful for mitigating fatigue associated with shift work. Shift work is intrinsically fatiguing, regardless of whether the shift worker is at home base or deployed.

Human factors in remotely piloted aircraft operations: HFACS analysis of 221 mishaps over 10 years.

BACKGROUND: A primary tool for evaluating fielded systems is to review mishaps. This study is a 10-yr cross-sectional quantitative analysis of the distribution and determinants of operator error in remotely piloted aircraft (RPA) mishaps within the U.S. military services using a standardized human factors taxonomy and a hierarchical model of human error. METHODS: Data on RPA mishaps during fiscal years 1994-2003 were obtained from the Air Force, Army, and Navy/Marines safety centers. Mishap reports were reviewed and human factors coded using the Department of Defense's Human Factors Analysis and Classification System (HFACS). Binary logistic regression was used to create models predicting operator error. RESULTS: A total of 221 mishaps were identified, of which 60.2% involved operations-related human causal factors. The frequency of human factors mishaps was 79.1%, 39.2%, and 62.2% for the Air Force, Army, and Navy/Marines, respectively. Latent failures at the organizational level were most prevalent and were associated with both operator error and mechanical failures. Predictors of operator error were technological environment and cognitive factors in the Air Force; organizational processes, psycho-behavioral factors, and crew resource management in the Army; and organizational processes, inadequate supervision, planned inappropriate operations, physical and technological environments, and cognitive and psycho-behavioral factors in the Navy. The frequency of specific types of errors differed between the services with skill-based errors more common in the Air Force and violations in the Army. CONCLUSION: Recurring human factors failure at the organizational, supervision, preconditions, and operator levels have contributed to more than half of RPA mishaps.

Evaluation of extended training for general practice in Northern Ireland: qualitative study.

OBJECTIVE: To evaluate participants' perceptions of the impact on them of an additional six months' training beyond the standard 12 month general practice vocational training scheme. DESIGN: Qualitative study using focus groups. SETTING: General practice vocational training in Northern Ireland. PARTICIPANTS: 13 general practitioner registrars, six of whom participated in the additional six months' training, and four trainers involved in the additional six months' training. MAIN OUTCOME MEASURES: : Participants' views about their experiences in 18 month and 12 month courses. RESULTS: Participants reported that the 12 month course was generally positive but was too pressurised and focused on examinations, and also that it had a negative impact on self care. The nature of the learning and assessment was reported to have left participants feeling averse to further continuing education and lacking in confidence. In contrast, the extended six month component was reported to have restimulated learning by focusing more on patient care and promoting self directed learning. It developed confidence, promoted teamwork, and gave experience of two practice contexts, and was reported as valuable by both ex-registrars and trainers. However, both the 12 and 18 month courses left participants feeling underprepared for practice management and self care. CONCLUSIONS: 12 months' training in general practice does not provide doctors with the necessary competencies and confidence to enter independent practice. The extended period was reported to promote greater professional development, critical evaluation skills, and orientation to lifelong learning but does not fill all the gaps.

Using the Freiburg Acuity and Contrast Test to measure visual performance in USAF personnel after PRK.

PURPOSE: Photorefractive keratectomy (PRK) may be an alternative to spectacle and contact lens wear for United States Air Force (USAF) aircrew and may offer some distinct advantages in operational situations. However, any residual corneal haze or scar formation from PRK could exacerbate the disabling effects of a bright glare source on a complex visual task. The USAF recently completed a longitudinal clinical evaluation of the long-term effects of PRK on visual performance, including the experiment described herein. METHODS: After baseline data were collected, 20 nonflying active duty USAF personnel underwent PRK. Visual performance was then measured at 6, 12, and 24 months after PRK. Visual acuity (VA) and contrast sensitivity (CS) data were collected by using the Freiburg Acuity and Contrast Test (FrACT), with the subject viewing half of the runs through a polycarbonate windscreen. Experimental runs were completed under 3 glare conditions: no glare source and with either a broadband or a green laser (532-nm) glare annulus (luminance approximately 6090 cd/m) surrounding the Landolt C stimulus. RESULTS: Systematic effects of PRK on VA relative to baseline were not identified. However, VA was almost 2 full Snellen lines worse with the laser glare source in place versus the broadband glare source. A significant drop-off was observed in CS performance after PRK under conditions of no glare and broadband glare; this was the case both with and without the windscreen. As with VA, laser glare disrupted CS performance significantly and more than broadband glare did. CONCLUSIONS: PRK does not appear to have affected VA, but the changes in CS might represent a true decline in visual performance. The greater disruptive effects from laser versus broadband glare may be a result of increased masking from coherent spatial noise (speckle) surrounding the laser stimulus.