Helping patients travel by air.

Although safe and rapid, air travel may present problems for people with certain medical conditions. Most medical emergencies that occur during a flight are preventable by judicious screening and preparation. We provide guidelines for physicians who are consulted about the wisdom of undertaking a journey by air. Potential stresses before, during and after the flight are outlined, including decreased atmospheric pressure, low humidity, turbulence, inactivity and time changes. We recommend precautionary measures for passengers with certain medical conditions, such as recent myocardial infarction, pulmonary disorders, pneumothorax, cerebrovascular accidents and diabetes and for those who have recently had surgery. The policy regarding air travel for pregnant women varies with each airline, but for certain conditions associated with pregnancy supplemental oxygen should be ordered before the trip. The special equipment and care that most airlines offer to ill or disabled people are described.     

Dietary and pharmacological intervention to mitigate the cardiopulmonary effects of air pollution toxicity

BackgroundExposure to air pollution contributes importantly to excess morbidity and mortality. And while regulatory actions under the “Clean Air Act” have saved millions of lives by improving air quality, there are still millions of people in the U.S. who live in areas where particulate air pollution (PM) levels exceed the U.S. Environmental Protection Agency's National Ambient Air Quality Standards. Therefore, apart from such localities working to attain such standards the protection of the health of public and in particular those at high risk might benefit from interventional strategies that would ameliorate air pollution's adverse health effects. Because inflammation and oxidative stress appear to mediate the health effects of air pollution, one interventional approach to consider is the use of dietary supplementation or medication with anti-inflammatory or antioxidant properties to block the biological responses that initiate the pathophysiological process that culminates in adverse health effects.Scope of reviewThis article reviews the capability of dietary supplementation, such as antioxidant vitamins, polyunsaturated fatty acids, and medications as a strategy to mitigate air pollution-induced subclinical cardiopulmonary effects.Major conclusionsAntioxidant vitamins C and E protect the lungs against short-term ozone and PM exposure. Polyunsaturated fatty acids, such as fish oil and olive oil appear to offer protection against short-term air pollution-induced adverse cardiovascular responses.General significanceTaking dietary supplements or medications with antioxidant or anti-inflammatory properties has the potential to provide at least partial protection against air pollution-induced adverse health effects in those individuals who are known to be most susceptible, namely those with pre-existing respiratory and cardiovascular diseases. This article is part of a Special Issue entitled Air Pollution, edited by Wenjun Ding, Andrew J. Ghio and Weidong Wu.     

Move that fatty acid: fuel selection and transport in migratory birds and bats

The metaphor of marathon running is inadequate to fully capture the magnitude of long-distance migratory flight of birds. In some respects a journey to the moon seems more appropriate. Birds have no access to supplementary water or nutrition during a multi-day flight, and they must carefully budget their body fat and protein stores to provide both fuel and life support. Fatty acid transport is crucial to successful non-stop migratory flight in birds. Although fat is the most energy-dense metabolic fuel, the insolubility of its component fatty acids makes them difficult to transport to working muscles fast enough to support the highly aerobic exercise required to fly. Recent evidence indicates that migratory birds compensate for this by expressing large amounts of fatty acid transport proteins on the membranes of the muscles (FAT/CD36 and FABPpm) and in the cytosol (H-FABP). Through endogenous mechanisms and/or diet, migratory birds may alter the fatty acid composition of the fat stores and muscle membranes to improve endurance during flight. Fatty acid chain length, degree of unsaturation, and placement of double bonds can affect the rate of mobilization of fatty acids from adipose tissue, utilization of fatty acids by muscles, and whole-animal performance. However, there is great uncertainty about how important fatty acid composition is to the success of migration or whether particular types of fatty acids (e.g., omega-3 or omega-6) are most beneficial. Migratory bats provide an interesting example of evolutionary convergence with birds, which may provide evidence for the generality of the bird model to the evolution of migration by flight in vertebrates. Yet only recently have attempts been made to study bat migration physiology. Many aspects of their fuel metabolism are predicted to be more similar to those of migrant birds than to those of non-flying mammals. Bats may be distinct from most birds in their potential to conserve energy by using torpor between flights, and in the behavioral and physiological trade-offs they may make between migration and reproduction, which often overlap.     

Collision avoidance in commercial aircraft Free Flight via neural networks and non-linear programming

In recent years there has been a great effort to convert the existing Air Traffic Control system into a novel system known as Free Flight. Free Flight is based on the concept that increasing international airspace capacity will grant more freedom to individual pilots during the enroute flight phase, thereby giving them the opportunity to alter flight paths in real time. Under the current system, pilots must request, then receive permission from air traffic controllers to alter flight paths. Understandably the new system allows pilots to gain the upper hand in air traffic. At the same time, however, this freedom increase pilot responsibility. Pilots face a new challenge in avoiding the traffic shares congested air space. In order to ensure safety, an accurate system, able to predict and prevent conflict among aircraft is essential. There are certain flight maneuvers that exist in order to prevent flight disturbances or collision and these are graded in the following categories: vertical, lateral and airspeed. This work focuses on airspeed maneuvers and tries to introduce a new idea for the control of Free Flight, in three dimensions, using neural networks trained with examples prepared through non-linear programming.     

Air Space Proportion in Pterosaur Limb Bones Using Computed Tomography and Its Implications for Previous Estimates of Pneumaticity

Air Space Proportion (ASP) is a measure of how much air is present within a bone, which allows for a quantifiable comparison of pneumaticity between specimens and species. Measured from zero to one, higher ASP means more air and less bone. Conventionally, it is estimated from measurements of the internal and external bone diameter, or by analyzing cross-sections. To date, the only pterosaur ASP study has been carried out by visual inspection of sectioned bones within matrix. Here, computed tomography (CT) scans are used to calculate ASP in a small sample of pterosaur wing bones (mainly phalanges) and to assess how the values change throughout the bone. These results show higher ASPs than previous pterosaur pneumaticity studies, and more significantly, higher ASP values in the heads of wing bones than the shaft. This suggests that pneumaticity has been underestimated previously in pterosaurs, birds, and other archosaurs when shaft cross-sections are used to estimate ASP. Furthermore, ASP in pterosaurs is higher than those found in birds and most sauropod dinosaurs, giving them among the highest ASP values of animals studied so far, supporting the view that pterosaurs were some of the most pneumatized animals to have lived. The high degree of pneumaticity found in pterosaurs is proposed to be a response to the wing bone bending stiffness requirements of flight rather than a means to reduce mass, as is often suggested. Mass reduction may be a secondary result of pneumaticity that subsequently aids flight.     

Caring for Older People. Public transport.

Most older people are mobile and able to use public transport without any problems. Those who are hard of hearing or have poor vision and those with mobility problems need not be deterred from using public transport. Though the design and provision of suitable buses, taxis, and trains is not always optimum, many now have imaginative features to help older passengers. Travel by air and sea needs extra planning for disabled elderly people, but helpful advice is available and much can be done to enable even the most disabled traveller to make long journeys confidently and in comfort.     

Emergency transport by aeromedical blimp.

Recently there has been an explosive growth in the use of helicopters and fixed wing aircraft for the transportation of patients who are ill and injured. Although using such methods of transport may result in faster access to health care centres, their ultimate role for the civilian population is unclear. Unfortunately, there are many problems associated with aeromedical transport, particularly with rotary wing aircraft, which have shown an alarming tendency to crash. The use of lighter than air vehicles (blimps, hot air balloons) might offer most of the advantages of conventional aieromedical transport, with an appreciable improvement in safety.     

Diagnostic Tools for Integrated In Situ Air Sparging Pilot Tests

In situ air sparging (IAS) pilot test procedures have been developed that provide rapid, on-site information about IAS performance. The standard pilot test consists of six activities conducted to look for indicators of infeasibility and to characterize the air distribution to the extent necessary to make design decisions about IAS well placement. In addition, safety hazards that need to be addressed prior to full-scale design are identified. Two additional pilot test activities are described in those cases where air distribution must be more precisely defined. The test activities include both chemical tests (tracking contaminant concentrations, dissolved oxygen and tracers) and physical tests (air flow rate and injection pressure, groundwater pressure response). Pilot test data from Eielson Air Force Base, Alaska illustrates implementation of the pilot test and interpretation of the data.     

Characteristics of a Beetle's Free Flight and a Flapping-Wing System that Mimics Beetle Flight

In this work, we first present a method to experimentally capture the free flight of a beetle (Allomyrina dichotoma), which is not an active flyer. The beetle is suspended in the air by a hanger to induce the free flight. This flight is filmed using two high-speed cameras. The high speed images are then examined to obtain flapping angle, flapping frequency, and wing rotation of the hind wing. The acquired data of beetle free flight are used to design a motor-driven flapper that can approximately mimic the beetle in terms of size, flapping frequency and wing kinematics. The flapper can create a large flapping angle over 140° with a large passive wing rotation angle. Even though the flapping frequency of the flapper is not high enough compared to that of a real beetle due to the limited motor torque, the flapper could produce positive average vertical force. This work will provide important experience for future development of a beetle-mimicking Flapping-Wing Micro Air Vehicle (FWMAV).     

Localization of the receptors that initiate and maintain flight in the cockroach, Periplaneta americana

Using local air streams, screening and surgical removal of the cerci and antennae, studies have been made on the receptors which provide for initiation and maintenance of the flight in the cockroach. It was shown that in suspended insect which lacks any contacts of legs with the base, the flight may be initiated by direct air currents either on the cerci, or antennae. Receptors which maintain the flight are located on the antennae and wings, the prolonged flight being provided mainly by antennae receptors.     

Amino acid metabolism during flight in tsetse flies.

Experiments carried out using teneral Glossina pallidipes indicate that flight can continue for at least 4 to 7 min after the thoracic proline reserves have fallen to low levels, suggesting that some other energy source is available. Earlier work suggests that alanine formed during flight is transported from the thorax to the abdomen where proline is resynthesized. Injection experiments using ¹⁴C alanine confirm that the transport mechanism does occur, that it is enhanced by flight, and that alanine is more rapidly incorporated into glutamate and proline in the abdomen than in the thorax. An analysis of published work shows that there is evidence for the involvement of residual blood meal amino acids even in the early stages of flight and supports the suggestion that they are of importance in prolonging flight. A decline in amino nitrogen during the early stages of flight is consistent with the action of glutamate dehydrogenase at this time. The poor flight durations in teneral flies may be due both to the low proline levels and to the absence of the residual blood meal. Very high energy consumptions are noted and appear to be related to the abnormally large musculature necessary for the fly's haematophagous and viviparous habits.     

Aeromedical evacuation of the seriously ill.

Almost any patient may be carried by air, but air transport introduces some special problems owing to the effects of altitude, noise, turbulence, and the special environment. Because of these factors it is important to know when considering a patient''s suitability for air transport the type of aircraft to be used, the flight profile--its duration and expected cabin altitudes--and the facilities available on board. It is essential to carry all equipment (as simple and as portable as possible), drugs, and diets that may be needed, and to be sure that all the skills and nursing help needed to deal with any possible problems are available.     

A combined hand- or power-operated sprayer for fly and mosquito control

A new sprayer is described which was designed in 1945 for the control of adult flies and mosquitoes with insecticides having a kerosene base. This sprayer has been shown in laboratory tests against houseflies, Musca domestica L., and yellow fever mosquitoes, Aedes aegypti L., to be highly efficient for both kill and knockdown and to achieve a particularly rapid knock-down of mosquitoes.
The sprayer can be operated with a hand pump or connected to a supply of compressed air. Air consumption is very low and when the sprayer is power-operated, optimum biological efficiency is obtained at 20 lb./sq.in. air pressure. There is no spitting or dribbling from the nozzle and the mist does not settle so rapidly as to cause any appreciable staining of the floor. Although robust it is light, easily manipulated and can be dismantled into component parts for cleaning. It has no adjustments; but the nozzle, which must be machined with precision, is automatically set in its most effective spraying position when screwed home tightly.     

Congestion Transition in Air Traffic Networks

Air Transportation represents a very interesting example of a complex techno-social system whose importance has considerably grown in time and whose management requires a careful understanding of the subtle interplay between technological infrastructure and human behavior. Despite the competition with other transportation systems, a growth of air traffic is still foreseen in Europe for the next years. The increase of traffic load could bring the current Air Traffic Network above its capacity limits so that safety standards and performances might not be guaranteed anymore. Lacking the possibility of a direct investigation of this scenario, we resort to computer simulations in order to quantify the disruptive potential of an increase in traffic load. To this end we model the Air Transportation system as a complex dynamical network of flights controlled by humans who have to solve potentially dangerous conflicts by redirecting aircraft trajectories. The model is driven and validated through historical data of flight schedules in a European national airspace. While correctly reproducing actual statistics of the Air Transportation system, e.g., the distribution of delays, the model allows for theoretical predictions. Upon an increase of the traffic load injected in the system, the model predicts a transition from a phase in which all conflicts can be successfully resolved, to a phase in which many conflicts cannot be resolved anymore. We highlight how the current flight density of the Air Transportation system is well below the transition, provided that controllers make use of a special re-routing procedure. While the congestion transition displays a universal scaling behavior, its threshold depends on the conflict solving strategy adopted. Finally, the generality of the modeling scheme introduced makes it a flexible general tool to simulate and control Air Transportation systems in realistic and synthetic scenarios.     

Steady-state pleural fluid flow and pressure and the effects of lung buoyancy

Both theoretical and experimental studies of pleural fluid dynamics and lung buoyancy during steady-state, apneic conditions are presented. The theory shows that steady-state, top-to-bottom pleural-liquid flow creates a pressure distribution that opposes lung buoyancy. These two forces may balance, permitting dynamic lung floating, but when they do not, pleural-pleural contact is required. The animal experiments examine pleural-liquid pressure distributions in response to simulated reduced gravity, achieved by lung inflation with perfluorocarbon liquid as compared to air. The resulting decrease in lung buoyancy modifies the force balance in the pleural fluid, which is reflected in its vertical pressure gradient. The data and model show that the decrease in buoyancy with perfluorocarbon inflation causes the vertical pressure gradient to approach hydrostatic. In the microgravity analogue, the pleural pressures would be toward a more uniform distribution, consistent with ventilation studies during space flight. The pleural liquid turnover predicted by the model is computed and found to be comparable to experimental values from the literature. The model provides the flow field, which can be used to develop a full transport theory for molecular and cellular constituents that are found in pleural fluid.     

Obligate vertebrate scavengers must be large soaring fliers

Among extant vertebrates, only the 23 species of vulture are obligate scavengers. We use an energetic modelling approach to explore the constraints imposed by an obligate scavenging lifestyle, and to ask whether obligate scavengers must always be avian and generally large-bodied users of soaring flight. Our model found that aerial scavengers always out-competed postulated terrestrial ones, mainly because flight allows area to be searched much more rapidly for carrion. Soaring was favoured over flapping flight because the reduction in flight speed (and so rate of area search) was more than compensated for by the decrease in the costs of transport. Large individual size is selected for if carrion is available in large packages, when obligate scavenger feed only infrequently, and so must be able to survive on body reserves in the periods between discovering food falls. In the absence of avian radiation, an obligate terrestrial scavenger seems energetically feasible, but we argue that such a beast is unlikely to have evolved. In birds, in order to become exclusive scavengers, vultures have needed to specialize for efficient soaring flight as a low energy form of travel, and as a consequence they have lost the agility needed to kill prey. In mammals, however, no comparable trade-off occurs. So for terrestrial carnivores there is probably no strong selection pressure towards being an exclusive scavenger. Indeed it will perhaps always be more advantageous to retain the flexibility of obtaining food by either predation or scavenging.     

The physiology and biomechanics of avian flight at high altitude

Many birds fly at high altitude, either during long-distanceflights or by virtue of residence in high-elevation habitats.Among the many environmental features that vary systematicallywith altitude, five have significant consequences for avianflight performance: ambient wind speeds, air temperature, humidity,oxygen availability, and air density. During migratory flights,birds select flight altitudes that minimize energy expenditurevia selection of advantageous tail- and cross-winds. Oxygenpartial pressure decreases substantially to as little as 26%of sea-level values for the highest altitudes at which birdsmigrate, whereas many taxa reside above 3000 meters in hypoxicair. Birds exhibit numerous adaptations in pulmonary, cardiovascular,and muscular systems to alleviate such hypoxia. The systematicdecrease in air density with altitude can lead to a benefitfor forward flight through reduced drag but imposes an increasedaerodynamic demand for hovering by degrading lift productionand simultaneously elevating the induced power requirementsof flight. This effect has been well-studied in the hoveringflight of hummingbirds, which occur throughout high-elevationhabitats in the western hemisphere. Phylogenetically controlledstudies have shown that hummingbirds compensate morphologicallyfor such hypodense air through relative increases in wing size,and kinematically via increased stroke amplitude during thewingbeat. Such compensatory mechanisms result in fairly constantpower requirements for hovering at different elevations, butdecrease the margin of excess power available for other flightbehaviors.