United States Air Research Articles

An empirical study of the resilience of the US and European air transportation networks

Air travel connects people and goods across vast geographical regions. However, operational inter-dependencies in the air transportation system due to factors such as aircraft, crew, and passenger connectivity also result in the spread of disruptions in the system. Our work uses tools from network science and control theory to characterize the relation between the inter-connectivity (i.e., network structure, both in terms of flights and delays) and the robustness of the air transportation system. These methods are applied to characterize the resilience of the air transportation networks in the United States (US) and Europe by considering the flight and delay network structures and delay dynamics. Our study reveals that stronger inter-connectivity in the US makes the system more susceptible to disruptions that spread rapidly. However, we also find that this higher connectivity enables greater flexibility and controllability while recovering from disruptions.

Understanding the influence of COVID-19 induced lockdown on urban thermal environment of Ranchi city, India

ABSTRACT The objective of the study is to understand the pattern of land surface temperature (LST) and normalized difference vegetation index (NDVI) developed in Ranchi city during Covid-19-induced lockdown (2020) and its comparison with previous years. The study incorporated Landsat 8 (Operational land imager) data from United States Geological Survey and air temperature and relative humidity data from power.larc.nasa.gov for the years 2017, 2019 and 2020. The results exposed a drastic change in the LST and NDVI pattern of the city. The mean LST of the city during April has declined from 39.80°C in 2017 to 32.38°C in 2020. Similarly, the mean LST of May also declined from 38.41°C in 2017 to 34.84°C in 2020. On the contrary, the city experienced an ascending growth of NDVI from 0.24 to 0.26 in April and May 2017 to 0.349 and 0.37 in 2020, respectively. Additionally, the city portrays declining air temperature with enhanced relative humidity. Ranchi city also exhibited relatively maximum area under ecologically excellent category in the year 2020 and reduced area under ecologically the worst category based on urban thermal field variance index. Thus, reduced temperature with augmented humidity and NDVI developed a healthy urban environment.

Curious Changes in Association of Complex Sunspot Groups with X-Ray Flares (≥M1) in Solar Cycles 22–24

Abstract We investigate the variations in the probabilities of complex sunspot groups (SGs)—large, asymmetric, or δ-type SGs—producing X-ray flares (≥M 1) in solar cycles (SCs) 22, 23, and 24 based on the SG data collected by the United States Air Force/Mount Wilson Observatory and the flare data recorded by Geostationary Operational Environmental Satellites. The following are the main findings. (1) For complex SGs in the whole disk as well as the northern and southern hemispheres during SC 22, their numbers and probabilities of producing flares change almost synchronously. (2) For complex SGs during SC 23, probabilities of producing flares during the early declining phase in the whole disk do not decrease with decreasing complex SG number; in the northern hemisphere, the probability of producing flares during the declining phase is significantly higher than that during the maximum phase; in the southern hemisphere, there is no definite variation trend in the probabilities of producing flares during the maximum and declining phases. (3) For complex SGs during SC 24, the probabilities of producing flares during the later rising and early declining phases are significantly higher than or comparable to those during the maximum phase no matter how their numbers change; in the northern hemisphere, the probability of producing flares during the rising phase is significantly higher than or at least comparable to that during the maximum phase; in the southern hemisphere, there is no definite variation trend in the probabilities of producing flares during the maximum and declining phases.

Phase Relation Between Large and Simple Sunspot Groups in Solar Cycles 22 – 24

In order to investigate the phase relation between the temporal variations of sunspot groups of various classes, firstly we use the separation scheme that was introduced by Kilcik et al. (Solar Phys.289, 4365, 2014b) to separate sunspot groups into large sunspot groups (D, E, and F classes in the modified Zurich classification) and simple sunspot groups (A and B classes) in Solar Cycles 22 – 24 collected by the United States Air Force/Mount Wilson Observatory (USAF/MWL). Then, using lagged-cross-correlation analysis and the block-bootstrap method, we calculate the correlation coefficients against time lags and determine the statistical significance of phase relation between large and simple sunspot groups in Solar Cycles 22 – 24, respectively. The main results that we obtained are summarized as follows: i) During Solar Cycles 22 and 24, the results – large sunspot groups lead or lag simple sunspot groups – are statistically insignificant and large sunspot groups should be in phase with simple sunspot groups. ii) During Solar Cycle 23, large sunspot groups statistically significantly lag simple sunspot groups in temporal phase.

Curriculum Evaluation and Transformation: Policies, Perspectives and Challenges

To date, the vast majority of developmental programs have had to be satisfied with assessing students’ learning within the confines of their programs. Although there were opportunities for indirect assessments, with graduate surveys or surveys of supervisors/employers, response rates tended to be low. Even when responses were received, they often came from people with little expertise in learning, making it difficult for educators to translate the feedback into actionable program improvements. The United States (US) Air Force has, however, decided to attempt what other learning institutions have not – arguably cannot. It is attempting to leverage its competency-based approach to performance assessment to enhance program evaluation. Because of the closed nature of this learning environment, where students graduate from US Air Force programs and go on to work in US Air Force jobs, there is a unique opportunity to assess learning as it is actually being applied in the workplace. Leveraging a competency-based force-development paradigm, the US Air Force has constructed a “foundational competencies” model for common knowledge, skills and abilities, complemented by occupational competencies specific to individual jobs, positions and specialties. These competencies are mapped to performance descriptions that determine levels of mastery. These performance descriptions are, in turn, mapped to rubrics that guide performance evaluations. Shortcomings in performance can be identified, quantified, and fed back to the developmental program for potential program modification or, for special updates to the force, to ensure Airmen perform their duties properly and achieve desired levels of mastery. This approach has been approved but is not yet fully implemented. The new Foundational Competencies Model has been developed and validated through a criterion-sampling methodology. In addition, many technical careers have created “occupational competencies” models delineated the specific knowledge, skills and abilities specific to their jobs. The full range of supporting assessment mechanisms, however, are still in the process of being designed and dispatched to facilitate ease of use and centralize data-gathering. This article overviews the US Air Force’s approach and its progress to date.

African American Veterans Career Transition Using the Transition Goals, Plans, Success (GPS) Program as a Model for Success

Increased deployments to combat operation areas have resulted in veterans transitioning from the military in more significant numbers. Likewise, African American veterans are also leaving the military in higher numbers. Transition assistance training is necessary to prepare these veterans for higher education and civilian employment since these are the most likely destinations for the successful transition of this population of veterans. Transition Goals, Plans, Success Program (Transition GPS) prepares military personnel for the transition back to civilian life. Transition GPS focuses on helping military personnel to become career-ready through mandatory curriculum-based training in a classroom setting before departing the military for civilian life. This study aims to understand better the transition experiences of African American veterans, their participation in the Transition GPS program, and the challenges they face obtaining employment and higher education after military service. Moreover, higher education is vital for the self-improvement and economic stability of African American veterans. The participants for this study were six African American veterans who served in the United States Army, Navy, Air Force, and Army National Guard. Each participant served in their respective branch of the military for 20 years or more. Veterans in this study highlighted the challenges they faced during their transition from the military to civilian life and acknowledged the importance of higher education. The themes that emerged are representative of the participants’ life experiences, military transition experiences, and demonstrates higher education’s role in a successful transition. The participants expressed the importance of family during their transitions, but they need help to better understand civilian careers and employment before leaving the military. Furthermore, African American veterans need career counseling to help them understand their transition experiences and help to prepare an adequate resume that translates their military skills into a civilian job match.

Long-Term Fate of Agent Orange and Dioxin TCDD Contaminated Soils and Sediments in Vietnam Hotspots

The soils, tropical climate, and network of canals and rivers of southern Vietnam have created one of the most diverse tropical jungles and intensely cultivated landscapes of Southeast Asia. This paradise has a long history of numerous wars, foreign occupations, and most recently the Second Indochina War (aka the Vietnam War 1965-1972) which defoliated rain forests and ancient wetland mangroves and left behind contaminated soil and sediment hotspots. During this war, the United States (US) military sprayed 80 million liters of Agent Orange contaminated with the dioxin TCDD in a guerrilla war against communist insurgents. Agent Orange was a synthetic plant growth regulator comprised of equal amounts of two herbicides 2,4-dichloro phenoxyacetic acid C8H6Cl2O3 (2,4-D) and 2,4,5-trichlorophenoxyacetic acid C8H5Cl3O3 (2,4,5-T). TCDD, the dioxin, 2,3,7,8-tetrachlorodibenzodioxin (C12H4Cl4O2) was an unintended byproduct of the accelerated combustion process used in the manufacture of herbicides containing 2,4,5-T. Agent Orange has frequently been blamed for soil and sediment contamination and long-term human health problems; however, the true source of harm is the dioxin TCDD. Agent Orange has a short half-life of days and weeks after application to vegetation, and has not been found to persist, after 50 years, in the water or soils of southern Vietnam. However, the half-life of dioxin TCDD depends on where it is deposited and varies from 1 to 3 years on soil surfaces that have been fully exposed to sunlight, to as long as 20 to 50 years or more when buried in tropical subsoils, and more than 100 years in river and sea sediments. Dioxin TCDD was heavily concentrated in the US Air Force bases in Vietnam where the herbicides were stored, loaded on planes and helicopters for aerial spraying, and used extensively around military base perimeter fences as a security measure to prevent surprise attacks. Bien Hoa Air Force base, 40 km northeast of Ho Chi Minh City, continues to be one of the mega-hotspots where after 48 years the dioxin TCDD levels in fish and shrimp are still high and fishing is banned in ponds and lakes adjacent to the airbase. Although expensive, one of the most effective remediation to dioxin TCDD contaminated soils is incineration which is the recommended method of dioxin TCDD disposal.

Deployment and Smokeless Tobacco Use Among Active Duty Service Members in the U.S. Military.

The prevalence of smokeless tobacco use among U.S. active duty service members has been much higher than in the U.S. general population. The association between deployment and smokeless tobacco use has not been well studied. We investigated the association between deployment and smokeless tobacco use among U.S. active duty service members. We also evaluated the modification effects from other factors related to smokeless tobacco use on the deployment-smokeless tobacco use association. Eligible active duty service members stationed at two military installations (Fort Bragg, NC, USA and Lackland Air Force Base, TX, USA) were recruited from July 2015 to May 2016. Each participant completed a self-administered questionnaire. Multivariable logistic regression was used to assess the association between deployment and smokeless tobacco use and estimated odds ratio (OR) and 95% confidence interval (CI). Stratified analysis was performed to evaluate modification effects from other commonly known factors related to smokeless tobacco use in military, specifically, cigarette smoking status, use among family members (family history of use), perception of harm, and use among military peers. Out of 2,465 study participants who completed the questionnaire, 548 were smokeless tobacco users. Service members who had been deployed to a combat zone had 1.39 fold (95% CI = 1.03-1.87) increased odds of using smokeless tobacco than those who never deployed to a combat zone. The odds of smokeless tobacco use among those who had been deployed once, twice, three times and four or more times to a combat zone were 1.27 (95% CI = 0.91-1.78), 1.30 (95% CI = 0.85-1.99), 2.49 (95% CI = 1.45-4.28), and 2.88 (95% CI = 1.71-4.86), respectively, with a significant dose-response trend (p for trend <0.0001). Further, subjects who served in combat units during deployment exhibited more than two-fold increased odds of use as compared with those who had never been deployed (OR = 2.03, 95% CI = 1.41-2.93). In stratified analysis, the association between deployment and smokeless tobacco use was only present among subjects who never smoked cigarettes, those without family history of smokeless tobacco use, and those who had low perception of harm of use. Military deployment was associated with smokeless tobacco use among active service members. However, the influence of military deployment on smokeless tobacco use was not equally strong on all service members. Subjects who never smoked cigarettes, who had no family history of use and who had low perception of harm were the most susceptible subgroups to deployment-related smokeless tobacco use. This study has implications to identify high-risk subgroups to reduce smokeless tobacco use in the U.S. military.

Distribution of American Houses Around the USA Air Force Soon after the Second World War in Fukuoka, Japan

Distribution of American Houses Around the USA Air Force Soon after the Second World War in Fukuoka, Japan

Use of multiple tools including lead isotopes to decipher sources of ozone and reactive mercury to urban and rural locations in Nevada, USA

Ambient air particulate matter (<2.5μm in diameter) samples were collected on two different filter types in 2014 and 2015 over 24h periods and analyzed for reactive mercury (gaseous oxidized mercury+particulate bound mercury) concentrations and lead isotopes to determine sources of pollution to three sites in Nevada, USA. Two sites were located on the western edge of Nevada (Reno, urban, 1370m and Peavine Peak, rural, high elevation, 2515m); the third location was ~485km east in rural Great Basin National Park, NV (2061m). Reactive mercury samples were collected on cation exchange membranes simultaneously with lead samples, collected on Teflon membranes.Lead isotopic ratios have previously identified trans-Pacific lead sources based on the 206/207 and 208/207 lead ratios. Influence from trans-Pacific air masses was higher from March to June associated with long-range transport of pollutants. Spring months are well known for increased transport across the Pacific; however, fall months were also influenced by trans-Pacific air masses in this study.Western North American background ozone concentrations have been measured and modeled at 50 to 55ppbv. Median ozone concentrations at both rural sites in Nevada were within this range. Sources leading to enhancements in ozone of 2 to 18ppbv above monthly medians in Nevada included emissions from Eurasia, regional urban centers, and global and regional wildfires, resulting in concentrations close to the USA air quality standard. At the high elevation locations, ozone was derived from pollutants being transported in the free troposphere that originate around the globe; however, Eurasia and Asia were dominant sources to the Western USA.Negative correlations between reactive mercury and percent Asian lead, Northern Eurasia and East Asia trajectories indicated reactive mercury concentrations at the two high elevation sites were produced by oxidants from local, regional, and marine boundary layer sources.

A Comparison of Avionics Open System Architectures

Building high-integrity, safety-critical systems is one of the primary activities of the projects within the United States (US) Department of Defense (DoD). Recognizing the need for affordable and effective solutions, the DoD calls for the use of Open System Architecture (OSA) solutions in Better Buying Power (BBP) 3.0 [1], Department of Defense Instruction 5000.02 [2], and the Defense Acquisition Guidebook section 4.3.18.15 [3]. The objectives of these documents are to avoid vendor lock, enable affordable capability evolution, and promote innovation. There are several activities underway to define standards that support the development of these systems. In the Unmanned Aerial Systems (UAS), the Unmanned Aerospace Systems (UAS) Command and Control (C2) Standard Initiative (UCI) standard has been defined to address the needs of providing an open architecture specification for unmanned aerial vehicles [4]. The Open Mission Systems (OMS) standard [5] developed by the US Air Force utilizes commercially developed Service Oriented Architecture (SOA) concepts and middleware in its definition along with the UCI standard. The Air Force is looking to extend the capabilities of the OMS standard to facilitate the rapid evolution of avionics systems. The Open Group has constructed a consortium of government, industry, and academia experts to develop the Future Airborne Capability Environment (FACE™) [6]. FACE is an open architecture effort that is intended to standardize the development of aviation components. The paper will present the basic definition of open systems architecture followed by a description of three of the OSA standard activities that are being conducted to address the direction from the DoD. The paper will then examine the similarities and differences between each of these initiatives. Finally, the paper will discuss the usability of OSA.

Letter to the editor: Regarding the editorial by Penttinen and Friede

To the editor: In the editorial by Penttinen and Friede, the authors summarised data from 2015 to 2016 on live attenuated influenza vaccine (LAIV) effectiveness in a Table and used the data in the Table to make several conclusions [1]. Unfortunately, the Table has several errors and, therefore, misrepresents the available data and studies. On 26 June 2016, the United States (US) Advisory Committee for Immunization Practices (ACIP) recommended that LAIV not be used during the 2016/17 season in the US [2]. Among all studies using a test-negative case–control design (TNCCD), the study from the US Centers for Disease Control and Prevention (CDC) (US Influenza Vaccine Effectiveness (VE) network) and the US Department of Defence (DoD) study (US Air Force School of Aerospace Medicine (USAFSAM) Sentinel Provider network) had the largest number of influenza A(H1N1)pdm09-infected children aged 2–17 years and larger or comparable numbers of children who received LAIV; these numbers were not correctly shown in the Table in the editorial. The US CDC study included 133 children aged 2–17 years who received LAIV (23 LAIV-vaccinated children had influenza A(H1N1)pdm09 infection) and 1,078 children who were unvaccinated. The US DoD study included 93 children vaccinated with LAIV (23 LAIV-vaccinated children had influenza A(H1N1)pdm09 infection) and 338 unvaccinated children (personal communication September 2016, Susan Federinko, USAFSAM). The youngest age for which LAIV is licensed for use in the US is two years; the US CDC VE estimates refer to children aged 2–17 years. The sample sizes for the other studies in the Table should also be consistently reported so that the same numerical comparisons are available for each study.

Implementing the US air quality standard for PM2.5 worldwide can prevent millions of premature deaths per year.

BackgroundAir pollution by fine aerosol particles is among the leading causes of poor health and premature mortality worldwide. The growing awareness of this issue has led several countries to implement air pollution legislation. However, populations in large parts of the world are still exposed to high levels of ambient particulate pollution. The main aim of this work is to evaluate the potential impact of implementing current air quality standards for fine particulate matter (PM2.5) in the European Union (EU), United States (US) and other countries where PM2.5 levels are high.MethodsWe use a high-resolution global atmospheric chemistry model combined with epidemiological concentration response functions to investigate premature mortality attributable to PM2.5 in adults ≥30 years and children <5 years. We perform sensitivity studies to estimate the reductions in mortality that could be achieved if the PM2.5 air quality standards of the EU and US and other national standards would be implemented worldwide.ResultsWe estimate the global premature mortality by PM2.5 at 3.15 million/year in 2010. China is the leading country with about 1.33 million, followed by India with 575 thousand and Pakistan with 105 thousand per year. For the 28 EU member states we estimate 173 thousand and for the United States 52 thousand premature deaths in 2010. Based on sensitivity analysis, applying worldwide the EU annual mean standard of 25 μg/m3 for PM2.5 could reduce global premature mortality due to PM2.5 exposure by 17 %; while within the EU the effect is negligible. With the 2012 revised US standard of 12 μg/m3 premature mortality by PM2.5 could drop by 46 % worldwide; 4 % in the US and 20 % in the EU, 69 % in China, 49 % in India and 36 % in Pakistan. These estimates take into consideration that about 22 % of the global PM2.5 related mortality cannot be avoided due to the contribution of natural PM2.5 sources, mainly airborne desert dust and PM2.5 from wild fires.ConclusionsOur results reflect the need to adopt stricter limits for annual mean PM2.5 levels globally, like the US standard of 12 μg/m3 or an even lower limit to substantially reduce premature mortality in most of the world.Electronic supplementary materialThe online version of this article (doi:10.1186/s12940-016-0170-8) contains supplementary material, which is available to authorized users.

Automatic Recognition of Sunspots in HSOS Full-Disk Solar Images

AbstractA procedure is introduced to recognise sunspots automatically in solar full-disk photosphere images obtained from Huairou Solar Observing Station, National Astronomical Observatories of China. The images are first pre-processed through Gaussian algorithm. Sunspots are then recognised by the morphological Bot-hat operation and Otsu threshold. Wrong selection of sunspots is eliminated by a criterion of sunspot properties. Besides, in order to calculate the sunspots areas and the solar centre, the solar limb is extracted by a procedure using morphological closing and erosion operations and setting an adaptive threshold. Results of sunspot recognition reveal that the number of the sunspots detected by our procedure has a quite good agreement with the manual method. The sunspot recognition rate is 95% and error rate is 1.2%. The sunspot areas calculated by our method have high correlation (95%) with the area data from the United States Air Force/National Oceanic and Atmospheric Administration (USAF/NOAA).

The effects of global change upon United States air quality

Abstract. To understand more fully the effects of global changes on ambient concentrations of ozone and particulate matter with aerodynamic diameter smaller than 2.5 μm (PM2.5) in the United States (US), we conducted a comprehensive modeling effort to evaluate explicitly the effects of changes in climate, biogenic emissions, land use and global/regional anthropogenic emissions on ozone and PM2.5 concentrations and composition. Results from the ECHAM5 global climate model driven with the A1B emission scenario from the Intergovernmental Panel on Climate Change (IPCC) were downscaled using the Weather Research and Forecasting (WRF) model to provide regional meteorological fields. We developed air quality simulations using the Community Multiscale Air Quality Model (CMAQ) chemical transport model for two nested domains with 220 and 36 km horizontal grid cell resolution for a semi-hemispheric domain and a continental United States (US) domain, respectively. The semi-hemispheric domain was used to evaluate the impact of projected global emissions changes on US air quality. WRF meteorological fields were used to calculate current (2000s) and future (2050s) biogenic emissions using the Model of Emissions of Gases and Aerosols from Nature (MEGAN). For the semi-hemispheric domain CMAQ simulations, present-day global emissions inventories were used and projected to the 2050s based on the IPCC A1B scenario. Regional anthropogenic emissions were obtained from the US Environmental Protection Agency National Emission Inventory 2002 (EPA NEI2002) and projected to the future using the MARKet ALlocation (MARKAL) energy system model assuming a business as usual scenario that extends current decade emission regulations through 2050. Our results suggest that daily maximum 8 h average ozone (DM8O) concentrations will increase in a range between 2 to 12 parts per billion (ppb) across most of the continental US. The highest increase occurs in the South, Central and Midwest regions of the US due to increases in temperature, enhanced biogenic emissions and changes in land use. The model predicts an average increase of 1–6 ppb in DM8O due to projected increase in global emissions of ozone precursors. The effects of these factors are only partially offset by reductions in DM8O associated with decreasing US anthropogenic emissions. Increases in PM2.5 levels between 4 and 10 μg m−3 in the Northeast, Southeast, Midwest and South regions are mostly a result of increase in primary anthropogenic particulate matter (PM), enhanced biogenic emissions and land use changes. Changes in boundary conditions shift the composition but do not alter overall simulated PM2.5 mass concentrations.

Liberalization of China–US air transport market: Assessing the impacts of the 2004 and 2007 protocols

This paper examines China's considerations in reaching the 2004 and 2007 Air Service Agreement Protocols with the United States (US) and the impacts of such policy on the China–US market from the perspective of China. Analysis shows that the 2004 and 2007 protocols have profound impacts on the China–US market. The two protocols have been associated with phenomenal traffic growth and intensified competition. Passengers also benefit from much more choice in terms of both airlines and routing. Over time, Chinese carriers' operating performance and financial performance have gradually improved after the liberalization expressed in the protocols. However, the industry's hub-building initiatives are still seriously challenged by competing hubs in Seoul and Tokyo which have diverted substantial number of passengers moving between the China and US markets. Such issues have to be addressed in order to create a win–win outcome for both countries.

Visualities of strategic vision: Lookout Mountain Laboratory and the deterrent state from nuclear tests to Vietnam

This article considers two visual cultures of America’s deterrent state in the Cold War, the cinematic and cybernetic, by following the history of the 600th Photographic Squadron of the United States (US) Air Force in Vietnam and its 1950s progenitor, the 1352nd Motion Picture Squadron, or Lookout Mountain Laboratory. We argue that cinematic and cybernetic visual cultures were at the heart of a Cold War visual alliance that was also a Cold War visual contest, and cameras were situated at the centre of the contest. Specifically, the cinematic and the cybernetic represent two distinct visualities of vision, as the Cold War cameras of the Air Force assumed either transcendental or transcendent positions. The former, in keeping with a cinematic visuality, was oriented towards casting America as a sight to see in the context of its war on communism, with cameras operating as a condition of possibility for the construction of the ‘image’, whereas the latter, in keeping with a cybernetic visuality, was oriented towards the American appetite to see, to monitor and survey the world over, with cameras operating as processors of ‘information’. The history of the 600th Photographic Squadron and its progenitor, Lookout Mountain Laboratory, suggests that the transition from cinematic to cybernetic visualities of vision was part of a broader transformation in the US Cold War state from a nuclear deterrent state to a supra-nuclear deterrent state.

9.1.2 Two‐stage Multi‐objective Analysis in the Assignment of Federal Air Marshals

AbstractThe United States Federal Air Marshal Service (FAMS) plays a critical role in ensuring safe travel aboard United States (US) air carriers. Federal Air Marshall agents, who operate out of field offices throughout the US, are assigned to accompany flights in order to deter and respond to hostile acts. In an era of limited resources, the FAMS is interested in optimally locating its field offices and agents to minimize the overall risk to the US air transportation system. This represents a highly constrained and complex optimization problem that resists standard techniques. In this paper, we demonstrate an approach that leverages the value‐focused thinking to model risk and optimize risk mitigation. Our approach uses a novel two‐stage approach to risk analysis that reduces the optimization burden and provides a solution to the FAMS.

Changing air mass frequencies in Canada: potential links and implications for human health

Many individual variables have been studied to understand climate change, yet an overall weather situation involves the consideration of many meteorological variables simultaneously at various times diurnally, seasonally, and yearly. The current study identifies a full weather situation as an air mass type using synoptic scale classification, in 30 population centres throughout Canada. Investigative analysis of long-term air mass frequency trends was completed, drawing comparisons between seasons and climate zones. We find that the changing air mass trends are highly dependent on the season and climate zone being studied, with an overall increase of moderate ('warm') air masses and decrease of polar ('cold') air masses. In the summertime, general increased moisture content is present throughout Canada, consistent with the warming air masses. The moist tropical air mass, containing the most hot and humid air, is found to increase in a statistically significant fashion in the summertime in 46% of the areas studied, which encompass six of Canada's ten largest population centres. This emphasises the need for heat adaptation and acclimatisation for a large proportion of the Canadian population. In addition, strong and significant decreases of transition/frontal passage days were found throughout Canada. This result is one of the most remarkable transition frequency results published to date due to its consistency in identifying declining trends, coinciding with research completed in the United States (US). We discuss relative results and implications to similar US air mass trend analyses, and draw upon research studies involving large-scale upper-level air flow and vortex connections to air mass changes, to small-scale meteorological and air pollution interactions. Further research is warranted to better understand such connections, and how these air masses relate to the overall and city-specific health of Canadians.

Needs and workflow assessment prior to implementation of a digital pathology infrastructure for the US Air Force Medical Service

Background: Advances in digital pathology are accelerating integration of this technology into anatomic pathology (AP). To optimize implementation and adoption of digital pathology systems within a large healthcare organization, initial assessment of both end user (pathologist) needs and organizational infrastructure are required. Contextual inquiry is a qualitative, user-centered tool for collecting, interpreting, and aggregating such detailed data about work practices that can be employed to help identify specific needs and requirements. Aim: Using contextual inquiry, the objective of this study was to identify the unique work practices and requirements in AP for the United States (US) Air Force Medical Service (AFMS) that had to be targeted in order to support their transition to digital pathology. Subjects and Methods: A pathology-centered observer team conducted 1.5 h interviews with a total of 24 AFMS pathologists and histology lab personnel at three large regional centers and one smaller peripheral AFMS pathology center using contextual inquiry guidelines. Findings were documented as notes and arranged into a hierarchal organization of common themes based on user-provided data, defined as an affinity diagram. These data were also organized into consolidated graphic models that characterized AFMS pathology work practices, structure, and requirements. Results: Over 1,200 recorded notes were grouped into an affinity diagram composed of 27 third-level, 10 second-level, and five main-level (workflow and workload distribution, quality, communication, military culture, and technology) categories. When combined with workflow and cultural models, the findings revealed that AFMS pathologists had needs that were unique to their military setting, when compared to civilian pathologists. These unique needs included having to serve a globally distributed patient population, transient staff, but a uniform information technology (IT) structure. Conclusions: The contextual inquiry method helped reveal similarities and key differences with civilian pathologists. Such an analysis helped identify specific instances that would benefit from implementing digital pathology in a military environment. Employing digital pathology to facilitate workload distribution, secondary consultations, and quality assurance (over-reads) could help the AFMS deliver more accurate, efficient, and timely AP services at a global level.