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Thermoregulation is the pits: use of thermal radiation for retreat site selection by rattlesnakes
Aaron R. Krochmal, George S. Bakken
Journal of Experimental Biology 2003 206: 2539-2545; doi: 10.1242/jeb.00471
Aaron R. Krochmal
George S. Bakken
Pitvipers (Viperidae: Crotalinae) possess unique sensory organs, the facial pits, capable of sensing subtle fluctuations in thermal radiation. Prey acquisition has long been regarded as the sole function of the facial pits. However, the ability to sense thermal radiation could also direct thermoregulatory behavior by remotely sensing nearby surface temperatures. Using a series of behavioral arenas of varying spatial complexity and ecological relevance, we surveyed the ability of the western diamondback rattlesnake Crotalus atrox to direct successful thermoregulatory movements with either functional or disabled facial pits. We found that western diamondback rattlesnakes could base thermoregulatory decisions on thermal radiation cues when their pits were functional, but not when blocked. Our results indicate that the facial pit is part of a generalized sense, and suggest thermoregulation as an alternative hypothesis to prey acquisition for the origin of facial pits.
Crotalus atrox
facial pit
behavioral thermoregulation
prey acquisition
thermal detection
Like many other ectotherms, pitvipers regulate their body temperature by adjusting activity patterns to utilize the heterogeneity of the thermal environment. Behavioral thermoregulation optimizes temperature-dependent physiological processes (Huey, 1982; Angilletta et al., 2002) but limits the time and place of activity and thus constrains other essential behaviors, including courtship (e.g. Navas and Bevier, 2001), foraging (e.g. Gvozdik, 2002), and predator avoidance (e.g. Mori and Burghardt, 2001). The ability to locate favorable microsites efficiently minimizes these constraints while maximizing time spent at optimal body temperatures (Huey, 1991). For example, the thermoregulatory precision of lizards exposed to a novel environment can improve after a learning period (Heath, 1965).
Little work has been devoted to investigating the sensory information by which ectotherms locate favorable microsites from a distance. As sunlight is the common cause of both visual illumination and solar heating, a few studies have tested the use of light intensity as a visual cue to the temperature of a microsite (e.g. Hertz et al., 1994; Sievert and Hutchinson, 1988). Under many circumstances, this may be adequate for successful thermoregulation (e.g. Hertz et al., 1994). However, visual illumination gives no direct information about temperature and can be misleading during the day (e.g. a dark rock in the sun would be hot though visually dark). Further, visual illumination is a largely ineffective cue at night, when residual temperature variations caused by solar heating are no longer associated with illumination cues.
In contrast, emitted thermal radiation is a direct cue that gives reliable information about nearby surface temperatures. Natural surfaces emit thermal radiation in direct proportion to their surface temperatures. Accordingly, emitted thermal radiation is a reliable and efficient means for distinguishing among microsites of varying thermal quality.
The pitvipers (Viperidae: Crotalinae) are named for their paired, thermally sensitive facial pits located midway between the eye and nostril on either side of the head. These organs are responsive to emitted thermal radiation and can detect variations in surrounding surface temperature (Bullock and Diecke, 1956; Cock Buning, 1983). Facial pits have been repeatedly shown to aid in orienting and striking towards prey (Noble and Schmidt, 1937; Bullock and Diecke, 1956; Cock Buning, 1983; Kardong and Mackessy, 1991; Kardong and Berkhoudt, 1999). Although no other behavioral roles have been demonstrated for facial pits, they could, in principle, be a part of a generalized sense used to examine any temperature variations in the local environment (Goris and Nomoto, 1967; Greene, 1997). For example, this ability to sense thermal radiation could be used to cue behavioral thermoregulation. This possibility has been summarily dismissed on neurological grounds (Bullock and Barrett, 1968; Barrett et al., 1970; Newman and Hartline, 1982) but has never been empirically tested in behavioral studies.
Neuroanatomical and behavioral evidence suggest that the eyes and facial pits are functionally integrated into a generalized multispectral visual sense. Neural output from the facial pits is combined with visual information in the optic tectum (e.g. Hartline et al., 1978). Behaviorally, one sense can compensate for deficiencies in the other. Kardong and Berkhoudt (1999) report that the predatory performance of rattlesnakes deprived of either visual or thermal stimuli did not differ from each other or from that of unimpaired animals, while animals deprived of both visual and thermal stimuli exhibited drastically hampered performances. Furthermore, Kardong and Mackessy (1991) report that the predatory performance of a congenitally blind rattlesnake did not differ from that of healthy conspecifics.
As the ability to sense temperature from a distance could greatly improve behavioral thermoregulation, it provides a good test of whether facial pits function as a generalized sense. The hypothesis that the facial pits aid thermoregulation makes two testable predictions. (1) Pitvipers can locate thermally favorable microhabitats in the absence of obvious cues (e.g. difference in visual illumination, temperature gradients and landmarks). (2) Pitvipers will subsequently lose this ability when their facial pits are temporarily disabled.
We tested these predictions by performing a series of behavioral experiments on western diamondback rattlesnakes Crotalus atrox, in which we presented snakes with a sequentially smaller target under conditions of increasing spatial complexity and ecological relevance. The western diamondback rattlesnake is a representative North American pitviper that inhabits desert and grassland areas. There, it escapes extreme temperatures by locating and moving towards thermal refugia (e.g. rodent burrows, rock crevices). We exploited this natural escape behavior to compare the ability of rattlesnakes with either functional or disabled facial pits to locate a thermal refuge within a stressful environment.
Experimental animals
We obtained 18 wild-caught western diamondback rattlesnakes Crotalus atrox Baird and Givaud 1853 (mean snout–vent length 77 cm) from a commercial supplier (Glades Herp, Inc., Fort Myers, FL, USA). Snakes were individually housed in 50 cm×27 cm×30 cm aquaria with newspaper substrates and supplied with water and shelter. All snakes were in captivity for a minimum of 1 year on a 12 h:12 h L:D cycle and 30°C:23.5°C temperature cycle before testing began.
Experimental temperatures
Snakes are not easily trained (e.g. Wolfle and Brown, 1940; Holtzman et al., 1999), and consequently the experiments were designed to exploit innate responses. We encouraged active behavioral thermoregulation in our study animals by subjecting them to a high, but sublethal, heat stress and providing a thermal refuge that they had to identify from a distance. Different temperatures thus provided both the motivation and the reward.
We held all thermal refugia at 30°C. Western diamondbacks regularly select a body temperature near 30°C under natural conditions (e.g. Cowles and Bogert, 1944; Beck, 1995, 1996). The appropriate ambient heat stress temperature to motivate escape behavior was less obvious, however. Few, if any, reliable data exist regarding upper temperature tolerance in C. atrox (Cowles and Bogert, 1944). We therefore conducted preliminary experiments in which we placed snakes in an arena held at a temperature typical of the upper selected limits for desert reptiles, 40-42°C. We used a thermal imager (ThermaCam® PM575, FLIR, North Billerica, MA, USA) to monitor body temperature (Jones and Avery, 1989) and observed behavior using closed-circuit video. When held at 40°C, animals displayed normal behavioral patterns for up to 1 h, and though body temperature approached 40°C, we never observed gaping, immobility, loss of righting responses, escape behavior or other indication of potentially injurious heat stress. Accordingly, we selected 40°C as the stressful environmental temperature.
Facial pit blocking
We temporarily disabled facial pits by first lightly anesthetizing snakes with isoflurane (Abbott Laboratories, North Chicago, IL, USA). When the snake was immobile, we placed a small polystyrene foam ball inside the facial pit cavity and glued a piece of aluminum foil over the facial pit opening using a latex adhesive (Skin Bond®, Smith-Nephew Inc., Fort Largo, FL, USA). The aluminum foil served to reflect incoming thermal radiation and retain the polystyrene foam ball, which acted as a piece of physical insulation against pit membrane heating by the aluminum. This modification of an existing technique (Kardong, 1992; Haverly and Kardong, 1996) provided a semi-permanent, reliable blockage that could easily be removed with mineral oil. Snakes received a sham procedure when dictated by experimental design. This consisted of anesthetizing snakes, inserting and removing a polystyrene foam ball from the facial pit cavity, and holding a glue-laden aluminum patch ca. 1 mm from the facial pit for 20 s.
Experimental arenas
The overall design consisted of three experiments, in which we presented snakes with sequentially smaller infrared targets (Fig. 1) in increasingly complex and ecologically relevant experimental arenas. The details of each arena are described below.
Thermal images of the refuges in the Y-maze (A), hide-box (B) and artificial burrow (C) experiments. All images were taken at a distance of 1 m from the radiating surface. The horizontal field of view subtended at an angle of 80°.
Experiment I
We first tested the ability of rattlesnakes to locate a favorable microsite in a simple Y-maze experiment. We constructed Y-mazes using transparent polycarbonate tube (8.9 cm o.d., 8.2 cm i.d.) and polyvinylchloride (PVC) plumbing components. The maze consisted of four main parts. The center section was a three-branch PVC Y shape with the base and two side branches fitted with open-ended 35 cm sections of polycarbonate tube. An acrylic window in the center branch allowed behavior to be videotaped as the snake emerged from the base and went down either of the branches. The base of the Y consisted of a removable snake carrier composed of a 45 cm long polycarbonate tube with a PVC cap on the distal end. The proximal end was fitted with a PVC coupling slotted to accommodate a sliding door. The two terminal ends of the maze branch (the `goals') consisted of similar carriers wrapped with copper heat exchange coils and covered with insulation. We attached the carrier and goals to the maze by slipping the coupling over the open-end tubes and tightening a nylon set screw.
To regulate the main part of the maze at a uniform and stressful level, the entire maze was placed in a walk-in environmental chamber (model 08083, Hotpack Corporation, Philadelphia, PA) set at 40°C. We regulated one goal at the same 40°C and the other (the `refuge') at 30°C by circulating water from two temperature-controlled water baths through the copper coils. During trials, water lines from the baths were attached to the goals using quick-connects.
To minimize unintentional cues, we randomized the association between a particular goal and its temperature, and we circulated water around both goals at the same rate. Also, we randomized refuge location (right- or left-maze branch) and the overall maze orientation within the environmental chamber (three-way rotational symmetry of Y-maze); this resulted in six unique maze configurations under which each snake was tested twice, once with functional and once with disabled facial pits. We thoroughly cleaned the maze with bleach solution between trials to remove odor trails. We verified the absence of air and surface temperature gradients near the branch point of the assembly using fine thermocouples in the air space and glued to the substrate, as well as thermography imaging of external maze surface temperature. Note that the appearance of a temperature gradient in Fig. 1A is an artifact caused by small-angle reflection of thermal radiation from the polished tubing surface. It is not seen when the maze is imaged at right angles to the surface.
At the start of each experiment, the carrier was covered with a black cloth and attached to a fitting on the side of a plastic tub. We moved each snake from its cage to the tub with a snake hook, whereupon the snake would attempt to hide by entering the carrier, which resembled a dark burrow. When it did, we closed the sliding door, removed the carrier, and attached it to the base of the maze. We began the experiment by raising the sliding door on the carrier and leaving the environmental chamber. All behavioral data were recorded with normal room illumination using closed-circuit video cameras. At the end of the experiment, we closed the sliding door in the goal containing the snake, removed the goal, and returned the snake to its cage.
We tested 12 wild-caught C. atrox (mean snout–vent length 68 cm) under a control–treatment–control design. First, all 12 snakes were tested with functional facial pits. These snakes then had their facial pits blocked and were retested. Finally, the same snakes had the blockages removed and were once again tested with functional pits. This experimental design enabled us to investigate the role of facial pits in thermoregulatory behavior while simultaneously detecting any learning or temporal (e.g. seasonal) effects or any lasting effects of facial pit blocking. The null hypothesis was that each snake would initially move toward the refuge in 50% of the trials. We scored each snake as having selected a branch when its head was 5 cm from the branch point and 60 cm from the opening of the refuge.
Experiment II
For this experiment, we presented snakes with a more complex thermoregulatory decision. We tested N=16 snakes (12 from the previous experiment; mean snout–vent length=74 cm) in a 1.8 m diameter circular metal stock tank painted flat gray (to prevent thermal radiation reflections and thus provide a uniform thermal radiation background) and filled with sand to a depth of 10 cm. The arena was housed in a walk-in environmental chamber held at 40°C. We placed four 18 cm×18 cm×18 cm hide boxes about the perimeter at 90° intervals. The inside of all hide boxes was painted flat black to provide a uniform visual signal contrasting with the gray background. The temperature of the back wall of each box was regulated by water circulated in copper coils soldered to the copper back wall. One of the four boxes was held 30°C, while the other hide boxes were regulated at 40°C. This arrangement allowed us to test snakes under conditions of greater spatial complexity using a more statistically powerful design.
We randomized the location of the 30°C refuge across the four possible locations, generating four orthogonal arena configurations. Snakes were tested twice under each configuration, once when facial pits were functional and once when they were blocked. We removed association between temperature and a specific hide box, and we used the same rate of water flow through the coils on all hide boxes. We mixed the sand thoroughly between trials to eliminate directional odor trails, and we verified the absence of air and surface temperature gradients with thermocouples and thermal imaging.
Snakes were initially held in a circular wire cage that allowed them to view and approach within 69 cm of the hide boxes. The upper part of the cage was covered with a black cloth so that the snakes could not observe the investigator leaving the environmental chamber. Otherwise, the snakes would assume a defensive coil and face the door indefinitely. After a pre-determined amount of time based on individual heating curve data (A. R. Krochmal and G. S. Bakken, unpublished data; mean time=4 min), we released the snakes by remotely lifting the cage a few cm. We scored the snake as having selected a particular refuge when it was moving toward a hide box and its head crossed a circle 64 cm from the hide boxes.
Analysis of experiment 1 did not demonstrate any lasting effects of blocking facial pits. Therefore, we simplified our experimental design. At the start of experimentation, half of the experimental animals had their facial pits blocked, while the other half underwent a sham procedure and maintained functional pits. Midway through experimentation, those with functional pits had their pits blocked, while those with blocked pits had the blockages removed. The null hypothesis was that each snake would initially move toward the refuge in 25% of the trials.
Experiment III
For the third experiment, we surveyed the ability of the same 16 snakes to distinguish among quasi-natural retreat sites of varying thermal quality. We simulated natural retreat sites by burying four temperature-controlled artificial burrows beneath the sand substrate of the same circular arena used in the previous experiment. The artificial burrows were polycarbonate tube assemblies similar to those used as Y-maze goals. Each was wrapped with copper tubing and insulation, inserted into a 20.3 cm diameter PVC sleeve, and buried in the sand with the opening facing the arena center. We regulated the arena at 40°C, and we maintained one burrow at 30°C and the others at the ambient 40°C by circulating water from regulated water baths through the copper coils. All other procedures, randomizations and parameters followed those used in the hide box trials.
During each of our three experiments, we tested snakes multiple times, corresponding to the number of orthogonal experimental configurations used to randomize potential confounding variables. For each snake and treatment we divided the number of initial movements toward the thermal refuge by the total number of trials to obtain a proportion of success. We arcsine transformed these proportions, calculated the mean proportion of success for each snake-treatment combination, and pooled means across snakes within a treatment (functional or disabled pits). In each experiment, the null hypothesis proportion of success was taken as (number of favorable refuges)/(number of potential refuges). We compared the observed result (mean for all snakes within each treatment group) to the null hypothesis using one-sample t-tests. To be conservative, we report two-tailed P values, even though the hypothesis is strictly one-tailed.
The presence of functional pits clearly allowed snakes to identify the cool refuge from a distance (Fig. 2A). When initially tested with functional pits, snakes located the thermally favorable (30°C) side of the maze far more often than predicted by chance (t=3.89, d.f.=11, P=0.003). When retested with blocked pits, the same individuals subsequently lost this ability (t=0.42, d.f.=11, P=0.68) but regained it when again tested with functional pits (t=4.00, d.f.=11, P=0.002).
Western diamondback rattlesnakes can rely on their facial pits to mediate thermoregulatory behavior. The plot compares means and 95% confidence intervals for rattlesnakes with either open or blocked facial pits in (A) the Y-maze, (B) the circular arena with hide boxes or (C) the circular arena fitted with artificial burrows. The dashed lines represent the experiment-specific null-hypothesis prediction.
We gathered no evidence for any detrimental impact of the facial pit blocking procedure, as snakes with open pits performed equally well whether or not the facial pit had been blocked and unblocked previously (two-sample t-test, t=–0.097, d.f.=1,10 P=0.92). Experimental snakes showed no side preference after removing the effect of temperature difference (χ2=1.39, P>0.1).
Functional pits allowed snakes to identify the cool refuge from a distance, even given the greater spatial complexity (Fig. 2B). Snakes with functional pits moved toward the thermal refuge significantly more often than predicted by chance (t=4.82, d.f.=15, P<0.001). Temporarily disabling the facial pits eliminated this ability (t=–0.085, d.f.=15, P>0.9). Pooled across all trials, snakes showed no preference for physical hide box locations (χ2=0.80, d.f.=3, P>0.75). In the trials where animals with functional pits did not move toward the refuge, movements were distributed evenly among the remaining hide boxes (χ2=0.35, d.f.=2, P>0.75).
When presented with a natural thermoregulatory target signal, experimental snakes relied on information from their facial pits to direct thermoregulatory movements (Fig. 2C).Animals with functional pits chose the 30°C burrow (t=4.0641, d.f.=5, P=0.002), while those with disabled pits selected burrows at random (t=–0.078, d.f.=15, P=0.951). Overall, snakes did not favor any physical burrow position (χ2=0.99, d.f.=3, P>0.75). In the trials where animals with functional pits did not move toward the refuge, movements were distributed evenly among the remaining burrows (χ2=2.05, d.f.=2, P>0.1).
Our experimental results clearly demonstrate that C. atrox can and do use their facial pits to direct thermoregulatory behavior, contradicting published assertions to the contrary, which were based on extrapolations from neurological data (Bullock and Barrett, 1968; Barrett et al., 1970). This previously undocumented behavior might be a significant component of behavioral thermoregulation in this species. This seems especially likely considering that experimental animals performed well under spatially complex and ecologically relevant conditions.
Though snakes with functional pits performed significantly better than predicted by chance, they did not perform perfectly. We conclude that performance was limited by motivation rather than by ability. This is, at least in part, a consequence of factors inherent in the experimental designs. First, the 40°C ambient temperature, while stressful, allowed snakes to explore the arenas indefinitely rather than seek immediate shelter. Indeed, several individuals displayed normal exploratory behavior in the arenas for as long as 60 min, and for much of this time the snakes had a thermographic body temperature near 40°C. Second, average performance in locating the cool refuge was unaffected by increased spatial complexity, while we would expect that performance would have been degraded if snakes had difficulty using thermal radiation cues.
We conclude that thermal radiation was the only cue available to the snakes to direct their movement toward the refuge. By eliminating or randomizing all non-thermal cues within our arenas (e.g. fluctuations in ambient light intensity, features of the physical environment), we potentially removed additional key sensory information with which snakes might mediate natural behavior. While minute thermal gradients existed very close to the cool refuge, we scored behavior on the basis of the direction of movement well before snakes would have encountered such gradients.
Our results give further support to the hypothesis that facial pits are general sense organs used to survey the environment, and that information derived from visual and thermal radiation is well integrated, perhaps even functioning as a single multispectral sense. Neuroanatomically, the neural output from the facial pits is integrated with visual information in the optic tectum, the area of the brain in which spatiotopic maps of the senses are formed (Hartline et al., 1978; Newman and Hartline, 1981). Moreover, more than half of the receptive units within the optic tectum exhibit cross-modality interactions (i.e. respond better to both facial pit and visual stimuli than to either stimulus alone), further emphasizing the functional integration of visual and thermal signals (Newman and Hartline, 1981). Behaviorally, the compensatory nature of visual and thermal information has already been established. For example, Kardong and Mackessy (1991) and Kardong and Berkhoudt (1999) showed that rattlesnakes strike as well when using only thermal or visual information as when using both senses, demonstrating parallel behavioral uses of these two senses.
Previously, prey acquisition was the sole documented role of facial pits and was therefore considered the adaptive function that drove their evolution (e.g. Greene, 1997). Other proposed uses of the facial pit included predator detection, den site selection and behavioral thermoregulation (e.g. Greene, 1997). While all these hypotheses are plausible, behavioral thermoregulation currently stands as the only documented role of facial pits aside from prey acquisition, and therefore suggests a viable alternative hypothesis for explaining their evolution.
The merits of three possible scenarios must be considered when pondering the adaptive forces that drove the evolution of facial pits. (1) Facial pits might have initially evolved as an aid in behavioral thermoregulation and were then recruited to assist in prey acquisition; (2) facial pits could have arisen as prey acquisition aids, with the ability to direct thermoregulatory movements arising later; (3) some as-yet-undocumented behavioral role (e.g. predator detection) was the adaptive force that drove the evolution of facial pits, with the currently demonstrated roles evolving subsequently. While other uses of the facial pit are likely to exist, they do not currently represent functional alternative hypotheses for comparative analysis, as they have not undergone empirical testing. The relative merits of the remaining two scenarios can be determined by considering the possible behavioral uses of the progenitor to the facial pit.
The precursor of the facial pit was probably relatively insensitive to emitted thermal radiation. Prey items at ecologically relevant distances give off weak thermal signals. Alternatively, environmental features subtend far larger solid angles and possess relatively larger temperature differences than do prey items, and they would therefore present a larger total thermal signal than would prey items. This would make environmental features more easily sensed than prey items by animals with a limited form of thermal detection. An ancestral, comparatively limited, ability to sense thermal radiation might therefore have been more useful for thermoregulation than for prey acquisition. Accordingly, we propose that the facial pit might have arisen as a thermoregulatory aid and was subsequently co-opted to acquire prey. Once established, the persistence of specialized thermal detection in pitvipers can be maintained by a variety of functions, including enhanced thermoregulation, prey acquisition and other proposed, but currently undocumented, behaviors.
Whether predation or thermoregulation was the original utility function driving the evolution of facial pits might be clarified by a combination of ecological and phylogenetic studies. First, the ability to direct thermoregulatory movement via the facial pits has only been documented in C. atrox subjected to high heat stress, and therefore might reflect recent ecological history. C. atrox is a xeric-adapted denizen of the American Southwest, where high daytime surface temperatures (50°C or higher) and high daily fluctuations in temperature make behavioral thermoregulation a constant care. Such habitats present both strong thermal infrared signals and clear and immediate benefits from efficient thermoregulatory decisions. Consequently, thermoregulatory use of the facial pit might be a recent ecological adaptation. It is less clear whether similar signals and selective pressures would be present in more stable, benign situations. A survey of the presence or absence of this behavior in pitvipers found in a variety of thermal regimes is a possible test of this hypothesis. Should only animals from thermally stressful environments use facial pits to mediate behavioral thermoregulation, it would appear to be a response to recent selection by local conditions. Thermoregulation is then less likely to be the original selective force that drove facial pit evolution. If, however, thermoregulatory use of the facial pits is found in species occupying a range of habitat types, then the case for a thermoregulatory origin is strengthened.
Further insight could come from a broad phylogenetic survey of the presence or absence of thermoregulatory behavior cued by thermal radiation across ophidian taxa. For example, true vipers, a closely related subfamiliy within the family Viperidae, possess supranasal sacs. These organs neurologically and histologically resemble a thermal detector (York et al., 1998). Additionally, some true viper species (Russell's viper Daboia russelli and puff adder Bitis arietans) are reportedly able to incorporate thermal information into their behavioral patterns (Breidenbach, 1990), further supporting the notion that they possess a thermal sensor. While quantitative neurophysiological data comparing the thermal sensitivity of true vipers and pitvipers are lacking, the structure of the facial pits suggests that they are likely to be more sensitive to emitted thermal radiation than supranasal sacs. Therefore, whether homologous with the facial pit or not, the supranasal sac might provide a model for the early radiation sensor.
The ability of the western diamondback rattlesnakes to mediate thermoregulatory decisions via the facial pit may play a substantial role in their natural thermoregulation, as animals exhibited this behavior under spatially complex and ecologically relevant conditions. Investigating the ability of snakes to rely on radiative cues to mediate thermoregulatory decisions within an ecological and phylogenetic framework will allow for tests of key functional and adaptive hypotheses regarding the use and evolution of the organ. Together, such studies may identify the phylogenetic root of this behavior and perhaps clarify the origins of this novel sense organ.
We thank T. Roth, A. Lynott, D. Sparks, W. Franklin, C. Oufiero and V. Quinn for assisting with the facial pit blocking procedures, and the reviewers for helpful comments on presentation. This research was supported by grants from Sigma Xi and The Indiana Academy of Science to A.R.K. and by NSF grant BSR 99-70209 to G.S.B. All experimental procedures were approved by the Indiana State University Institutional Animal Care and Use Committee (Protocol # 99-6:AKB, #01-03:AK/GB).
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Angilletta, M. J., Jr, Niewiarowski, P. H. and Navas, C. A. (2002). The evolution of thermal physiology in ectotherms. J. Therm. Biol. 27,249 -268.
Barrett, R., Maderson, P. F. A. and Meszler, R. M. (1970). The pit organs of snakes. In Biology of the Reptilia, vol. 2 (ed. C. Gans and T. S. Parsons), pp. 277-300. London: Academic Press.
Beck, D. D. (1995). Ecology and energetics of three sympatric rattlesnake species in the Sonoran Desert. J. Herpetol. 29,211 -223.
Beck, D. D. (1996). Effects of feeding on body temperatures of rattlesnakes: a field experiment. Physiol. Zool. 69,1442 -1455.
Breidenbach, C. H. (1990). Thermal cues influence strikes in pitless vipers. J. Herpetol. 24,448 -450.
Bullock, T. H. and Barrett, R. (1968). Radiant heat receptors in snakes. Commun. Behav. Biol. A 1, 19-29.
Bullock, T. H. and Diecke, F. P. J. (1956). Properties of an infra-red receptor. J. Physiol. (Lond.) 134,47 -87.
Cowles, R. B. and Bogert, C. M. (1944). A preliminary study of the thermal requirements of desert reptiles. Bull. Am. Museum Nat. Hist. 83,265 -296.
de Cock Buning, T. (1983). Thermal sensitivity as a specialization for prey capture and feeding in snakes. Amer. Zool. 23,363 -375.
Goris, R. C. and Nomoto, M. (1967). Infrared reception in oriental crotaline snakes. Comp. Biochem. Physiol. 23,879 -892.
Greene, H. W. (1997). Snakes: The Evolution of Mystery in Nature. Princeton, NJ: Princeton University Press.
Gvozdik, L. (2002). To heat or save time? Thermoregulation in the lizard Zootoca vivipara (Sqaumata: Lacertidae) in different thermal environments along an altitudinal gradient. Can. J. Zool. 80,479 -492.
Hartline, P. H., Kass, L. and Loop, M. S. (1978). Merging of modalities in the optic tectum: infrared and visual integration in rattlesnakes. Science 199,1225 -1229.
Haverly, J. E. and Kardong, K. V. (1996). Sensory deprivation effects on the predatory behavior of the rattlesnake, Crotalus viridis oreganus. Copeia 1996,419 -428.
Heath, J. E. (1965). Temperature regulation and diurnal activity in horned lizards. Univ. Calif. Pub. Zool. 64,97 -136.
Hertz, P. E., Fleishman, L. J. and Armsby, C. (1994). The influence of light intensity and temperature on microhabitat selection in two Anolis lizards. Func. Ecol. 8,720 -729.
Holtzman, D. A., Harris, T. W., Aranguren, G. and Bostock, E. (1999). Spatial learning of an escape task by young corn snakes, Elaphe guttata guttata. Anim. Behav. 57, 51-60.
Huey, R. B. (1991). Physiological consequences of habitat selection. Amer. Nat. 137,S91 -S115.
Huey, R. B. (1982). Temperature, physiology, and the ecology of reptiles. In Biology of the Reptilia, vol. 12 (ed. C. Gans and F. H. Pough), pp. 25-91. London: Academic Press.
Jones, S. M. and Avery, R. A. (1989). The use of a pyroelectric vidicon infrared camera to monitor the body temperatures of small terrestrial vertebrates. Func. Ecol. 3, 373-377.
Kardong, K. V. (1992). Proximate factors affecting guidance of the rattlesnake strike. Zool. Jb. Anat. 122,233 -244.
Kardong, K. V. and Berkhoudt, H. (1999). Rattlesnake hunting behavior: correlations between plasticity of predatory performance and neuroanatomy. Brain Behav. Evol. 53, 20-28.
Kardong, K. V. and Mackessy, S. P. (1991). The strike behavior of a congenitally blind rattlesnake. J. Herpetol. 25,208 -211.
Mori, A. and Burghardt, G. M. (2001). Temperature effects on anti-predator behavior in Rhabdophis tigrinus, a snake with toxic nuchal glands. Ethology 107,795 -811.
Navas, C. A. and Bevier, C. R. (2001). Thermal dependency of calling performance in the eurythermic frog Colostethus subpunctatus. Herpetologica. 57,384 -395.
Newman, E. A. and Hartline, P. H. (1981). Integration of visual and infrared information in bimodal neurons of the rattlesnake optic tectum. Science 213,789 -791.
Newman, E. A. and Hartline, P. H. (1982). The infrared `vision' of snakes. Sci. Amer. 246,116 -127.
Noble, G. K. and Schmidt, A. (1937). The structure and function of the facial and labial pits of snakes. Proc. Am. Phil. Soc. 77,263 -288.
Sievert, L. M. and Hutchison, V. H. (1988). Light versus heat: Thermoregulatory behavior in nocturnal lizard (Gekko gecko). Herpetologica 44,266 -273.
Wolfle, D. L. and Brown, C. S. (1940). A learning experiment with snakes. Copeia 1940, 134.
York, D. S., Silver, T. M., and Smith, A. A. (1998). Innervation of the supranasal sac of the puff adder. Anat. Rec. 251,221 -225.
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Despite 2020's challenges, we were able to bring a number of long-term projects and new ventures to fruition. As we enter a new year, join us as we reflect on the triumphs of the last 12 months.
Critical temperature window sends migratory black-headed buntings on their travels
The spring rise in temperature at black-headed bunting overwintering sites is essential for triggering the physical changes that they undergo before embarking on their spring migration – read more.
Developmental and reproductive physiology of small mammals at high altitude
Cayleih Robertson and Kathryn Wilsterman focus on high-altitude populations of the North American deer mouse in their review of the challenges and evolutionary innovations of pregnant and nursing small mammals at high altitude.
"Being able to publish Open Access articles free of charge means that my article gets maximum exposure and has maximum impact, and that all my peers can read it regardless of the agreements that their universities have with publishers."
Professor Roi Holzman (Tel Aviv University) shares his experience of publishing Open Access as part of our growing Read & Publish initiative. We now have over 60 institutions in 12 countries taking part – find out more and view our full list of participating institutions.


Hollis Watkins was born in Lincoln County, Mississippi, as the twelfth child of a sharecropping family. He became the first Mississippi student to join SNCC as a voting rights organizer at the age of nineteen. He is the co-founder and current president of Southern Echo, Inc., a "leadership development, education, training, and technical assistance organization dedicated to empowering local residents throughout Mississippi and the Southern region to make political, economic, educational, and environmental systems accountable to the needs and interests of the African-American community.


PREWAR MEAD RANGER BICYCLE DROP STAND KICKSTAND SCHWINN B6 DX VINTAGE ELGIN B10E. Here is a cool "drop stand" kickstand which was removed from a prewar Schwinn balloon tire tire bicycle with 26 wheels. This fits many vintage bikes such as Schwinn, DX, B6, Liberty, Henderson, Motorbike, Excelsior, Admiral, Monark, Silver King, Elgin, Hawthorne, Hiawatha, Harley, Indian, etc. Restore it for show or leave it in its "rat rod" type patina for fun.
A cool item for display as well. Dropstands ALWAYS seem to be missing from old bikes! A great item for display or to use. Includes the clip and the dropstand with the correct ears shown. Has some silver paint as shown.
The links move but it could use a good cleaning and lubrication! They are all available right now!
I try my very best to describe as accurately as possible. The item "PREWAR MEAD RANGER BICYCLE DROP STAND KICKSTAND SCHWINN B6 DX VINTAGE ELGIN B10E" is in sale since Thursday, August 16, 2018.


MacroPoint is a supply chain visibility platform that helps shippers, brokers and logistics service providers see their freight in transit in real time – offering predictive analytics to keep supply chains running efficiently.
While we're incredibly proud of how far we've come, we've only scratched the surface. SGE's ability to rapidly understand the business opportunity in front of us and move quickly to capture it, provided us with tremendous value within the funding process. SGE is a group of extraordinary people that bring their own expertise, finances, and relationships to the table in a way that is truly unique and impactful. Their cerebral and creative approach to working with us in a very agile way has created a refreshing dynamic allowing our business to grow very quickly.


Five Unconventional Knowledge About Painting That You Can't Learn From Books.
Five Unconventional Knowledge About Painting That You Can't Learn From Books.
Stay clear of these common Five Unconventional Knowledge About Painting That You Can't Learn From Books. challenges with these skilled painting tips, and also everybody will certainly assume you employed a professional.
There's absolutely nothing like a brand new coat of paint to entirely change a room. With an overwhelming choice of paint alternatives out there and also so numerous methods to make a little mistake, also the most ready painter is bound to make a mistake. Fortunately, we've discovered some straightforward services to common painting blunders so you can discover to paint like a pro.
Applying water-based latex paint with a natural-bristle brush will certainly result in bristles that are limp from taking in the water in the paint, making the paint almost difficult to spread. Synthetic brushes, made from nylon and polyester, are the perfect match for water-based latex paint.
Taping ensures professional-looking outcomes, however when left on for an extended amount of time, can cause peeling off paint upon elimination. If you've allow it rest for also long and the paint begins coming up, you're not out of luck. You can additionally attempt utilizing a strike clothes dryer to warmth up as well as loosen up the sticky, using your fingers to roll it away from the wall.
Paint does not manage extreme temperatures really well, so if you're starting a paint job make sure you're conscious of the weather. Extreme warmth will make paint bubble or will certainly dry paint as well swiftly, leaving you with an irregular surface. If your paint isn't applying effectively, check with the manufacturer to see what the optimum temperature is for the paint.
When going from a dark paint shade to a lighter one, guide becomes important in preventing the old color from bleeding with. You can fix this issue by securing the timber with a tannin-blocking guide prior to painting.
The area where the wall satisfies the ceiling does not leave much area for inaccuracy. When tackling this limited space, it's very easy to bump the ceiling with the roller, creating a difficult touch-up work. Quickly spray some home window cleaner on the area as well as clean away if the paint is still wet. The most effective method to stop this issue is by taping off the ceiling and brushing on a straight strip of paint to cover the top 5 approximately inches of the wall. This will give you a charitable buffer zone, allowing you to avoid the ceiling.
Typically selected for its durability, shiny paint has exceptional resistance to dirt and also grease. The same thing that protects glossy surface areas from fingerprints as well as spots additionally maintains brand-new paint from adhering effectively to them.
Painting over wallpaper is no more difficult than painting any other wall, however there is one caution. Water-based paints as well as primers might reactivate wallpaper adhesive, creating it to bubble up or remove. Instead, utilize an oil-based primer to prevent any type of issues with correct attachment.
With an overwhelming selection of paint options out there as well as so several ways to make a little bad move, even the most prepared painter is bound to make a blunder. Applying water-based latex paint with a natural-bristle brush will certainly result in bristles that are limp from absorbing the water in the paint, making the paint almost difficult to spread out. Paint does not deal with extreme temperatures really well, so if you're beginning a paint task make sure you're conscious of the climate. Extreme heat will make paint bubble or will dry out paint as well quickly, leaving you with an irregular coating. If your paint isn't using properly, check with the manufacturer to see what the optimum temperature level is for the paint.
At Alex Trend Painters, we complete all type of house painting, wallpapering, commercial painting, interior and exterior painting and 3d wall panels work in Dublin and Five Unconventional Knowledge About Painting That You Can't Learn From Books. for businesses large and small, creating usable vibrant spaces that help you get the best out of your team. Get in touch to discuss your requirements or request your free quote today.


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MUSIC FAVORITES OF THE YEAR
Music News 12/9/2020
To buy any of these titles e-mail András Goldinger agoldinger@politics-prose.com or call the store: (202) 364-1919
BLACK SWANS (Parnassus, $13.98) – Black Swan and Broome Records were the first Black-owned record labels, and the first to record Black artists singing classical concert music, including opera arias and spirituals, in the years 1917 – 1922.
Black Swans is an important new collection of some of these recordings, most never reissued before.
Artists include baritones Harry Burleigh and Edward H.S. Boatner, sopranos Florence Cole Talbert and Antoinette Garnes, pianist R Nathaniel Dett, contralto Hattie King Reavis, and violinist Clarence Cameron White. Perhaps the most famous artist of the period was tenor Roland Hayes, who produced, recorded and distributed his own records.
NPR had a story on Black Swans in December, and the Parnassus label features a fascinating hour-long presentation on the background, and the making of this collection.
Barry Gibb & Friends, GREENFIELDS: The Gibb Brothers' Songbook Vol. 1 (Capitol, $14.98) – To say that the songs of the Bee Gees have been influential is an understatement. But the influence on the Gibbs Brothers growing up in Australia of country music has not been written about much until now. With Greenfields, some of the best country and "Americana" artists pay tribute on duets with Barry Gibb, the sole surviving member of the Bee Gees. Artists on Greenfield include Dolly Parton, Alison Krauss, Jason Isbell, Gillian Welch & David Rawlings, Little Big Town, and Brandi Carlile. Aussies Keith Urban, Tommy Emmanuel and Olivia Newton-John are also featured.
BEETHOVEN: SYMPHONIES 1 – 9 (Concertgebouw Orchestra Live, 5 CDs, $55.98) – This is another fascinating release to celebrate Beethoven's 250th anniversary, and shows the many different approaches a conductor can take with the Symphonies. Each of Beethoven's nine Symphonies are conducted by a different conductor, all recorded live with the Concertgebouw Orchestra. Nos. 1 through 9 are conducted by, respectively, David Zinman, Leonard Bernstein, Nikolaus Harnoncourt, Herbert Blomstedt, Mariss Jansons, Roger Norrington, Carlos Kleiber, Philippe Herreweghe, and Antal Doráti.

redpajama_set_name: RedPajamaCommonCrawl


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Harvey L. Neiman Health Policy Institute and Georgia Institute of Technology to Establish Health Economics and Analytics Lab (HEAL)
The American College of Radiology's Neiman Institute and the Georgia Institute of Technology announced a new five-year, $3 million research partnership to establish the Health Economics and Analytics Lab (HEAL) within Georgia Tech's Ivan Allen College of Liberal Arts. HEAL will focus on applying big data analytics and artificial intelligence to large-scale medical claims databases — with a focus on medical imaging — to better understand how evolving health care delivery and payment models affect patients and providers.
"The HEAL will provide needed research to inform the national medical imaging policy debate and develop new approaches for improving population health," said Danny R. Hughes, executive director of the Neiman Institute and Georgia Tech professor of economics, who will lead the lab. "Drawing on Georgia Tech's unparalleled strength in interdisciplinary research, the HEAL is uniquely positioned to exploit the vast stores of medical data now available to ensure we move toward a sustainable health care system."
The center aligns well with Georgia Tech's core research areas, said President G.P. "Bud" Peterson.
"At Georgia Tech, one of our fundamental missions is help solve society's most challenging questions," Peterson said. "Issues of population health, cost, and access to health care are certainly among the most complicated we face. I am certain Georgia Tech's strong emphasis on data engineering and public policy will provide a firm foundation for Dr. Hughes and the HEAL team."
The lab will support full-time post-doctorate researchers, graduate research assistants, and affiliated Georgia Tech faculty to produce both methodological and policy-oriented research. A secondary aim of HEAL is to provide training and mentorship to radiologists interested in performing research into health economics and health policy.
Jacqueline Royster, dean of the Ivan Allen College of Liberal Arts, said the center will bring new possibilities for research and collaboration to Georgia Tech and the Neiman Institute.
"We are excited by the opportunities HEAL will bring to both organizations," she said. "This new lab will benefit from the enormous breadth of top-notch interdisciplinary expertise across Georgia Tech and in the Ivan Allen College of Liberal Arts, from economics, public, policy, and data analysis to artificial intelligence, engineering, and computer science."
In addition to financial support, the Neiman Institute will provide HEAL researchers access to their extensive data resources, to include large-scale medical claims databases covering millions of U.S. residents.
"This partnership provides a tremendous opportunity to leverage the Neiman Institute's policy expertise with the analytical capabilities of a world-class engineering institution to address the pressing problems of improving population health, increasing access to medical care, and reducing medical costs." said Geraldine McGinty, Chair of the American College of Radiology's Board of Chancellors.
To arrange an interview with a Neiman Institute spokesperson, contact Nichole Gay at (703) 648-1665 or ngay@neimanhpi.org.
The Harvey L. Neiman Health Policy Institute is one of the nation's leading medical imaging socioeconomic research organizations. The Neiman Institute studies the role and value of radiology and radiologists in evolving health care delivery and payment systems and the impact of medical imaging on the cost, quality, safety and efficiency of health care. Visit us at www.neimanhpi.org and follow us on Twitter, LinkedIn and Facebook.
About the Ivan Allen College of Liberal Arts
Georgia Tech's Ivan Allen College of Liberal Arts is recognized nationally and internationally for teaching and research examining the human context of engineering, science, and technology. The College is comprised of six schools – Economics; History, Technology, and Society; The Sam Nunn School of International Affairs; Literature, Communication, and Culture; Modern Languages; Public Policy; and Georgia Tech's Army, Air Force, and Navy ROTC units. It offers ten bachelor of science degrees, seven master's degrees, and six doctoral degrees. Students are prepared for professional leadership in government, business, public policy, international affairs, law, medicine, technology, and new media. Founded in 1990, the College is named in honor of former Atlanta Mayor Ivan Allen Jr. (1911 – 2003).
About the Georgia Institute of Technology
The Georgia Institute of Technology, also known as Georgia Tech, is one of the nation's leading research universities — a university that embraces change while continually creating the next. The next generation of leaders. The next breakthrough startup company. The next life-saving medical treatment. Georgia Tech provides a focused, technologically based education to more than 25,000 undergraduate and graduate students. Georgia Tech has many nationally recognized programs, all top-ranked by peers and publications alike, and is ranked in the nation's top 10 public universities by U.S. News and World Report. It offers degrees through the Colleges of Computing, Design, Engineering, Sciences, the Scheller College of Business, and the Ivan Allen College of Liberal Arts. As a leading technological university, Georgia Tech has more than 100 centers focused on interdisciplinary research that consistently contribute vital research and innovation to American government, industry, and business.
The HEAL will provide needed research to inform the national medical imaging policy debate and develop new approaches for improving population health


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Figure 1. Decision Model for Automated External Defibrillators (AEDs)
The square node represents the choice of AED deployment strategy. Circles are chance nodes. The plus sign indicates that the subtrees at all chance nodes numbered 1 are the same as for strategy A. A patient who survives to hospital discharge enters a Markov process (represented by the rectangle containing 2 circles and an arrow), which models the possibility of death occurring on an annual basis, and continues until death.
Figure 2. One-Way Sensitivity Analyses of the Cost-effectiveness of Automated External Defibrillator (AED) Deployment (Strategy E)
The bars indicate the variability of the cost-effectiveness ratio (x-axis) caused by changes in the value of the indicated variable, all other variables being held constant. Labels on the horizontal bars indicate the range of each 1-way sensitivity analysis. QALY indicates quality-adjusted life-year.
Figure 3. Automated External Defibrillators (AEDs) Deployment Strategies
The slope of the line of optimality indicates incremental cost-effectiveness. Strategies below and to the right of the line of optimality are dominated (more expensive and/or less effective). QALY indicates quality-adjusted life-year; BLS, basic life support.
Table 1. Cost-effectiveness Analysis of Automated External Defibrillators (AEDs)*
Table 2. Model Variables, Base-Case Values, and Ranges
Table 3. Results of Cost-effectiveness Analysis*
Gillum RF. Sudden coronary death in the United States: 1980-1985. Circulation.1989;79:756-765.Google Scholar
National Center for Health Statistics. Health United States 2000. Hyattsville, Md: Centers for Disease Control and Prevention; 2000.
Marenco JP, Wang PJ, Link MS. et al. Improving survival from sudden cardiac arrest. JAMA.2001;285:1193-1200.Google Scholar
Vukov LF, White RD, Bachman JW, O'Brien PC. New perspectives on rural EMT defibrillation. Ann Emerg Med.1988;17:318-321.Google Scholar
Auble TE, Menegazzi JJ, Paris PM. Effect of out-of-hospital defibrillation by basic life support providers on cardiac arrest mortality: a meta-analysis. Ann Emerg Med.1995;25:642-648.Google Scholar
Eisenberg MS, Hallstrom AP, Copass MK. et al. Treatment of ventricular fibrillation. JAMA.1984;251:1723-1726.Google Scholar
Weaver WD, Hill D, Fahrenbruch CE. et al. Use of the automatic external defibrillator in the management of out-of-hospital cardiac arrest. N Engl J Med.1988;319:661-666.Google Scholar
Kellermann AL, Hackman BB, Somes G, Kreth TK, Nail L, Dobyns P. Impact of first-responder defibrillation in an urban emergency medical services system. JAMA.1993;270:1708-1713.Google Scholar
Stults KR, Brown DD, Schug VL, Bean JA. Prehospital defibrillation performed by emergency medical technicians in rural communities. N Engl J Med.1984;310:219-223.Google Scholar
Valenzuela TD, Roe DJ, Nichol G. et al. Outcomes of rapid defibrillation by security officers after cardiac arrest in casinos. N Engl J Med.2000;343:1206-1209.Google Scholar
Page RL, Joglar JA, Kowal RC. et al. Use of automated external defibrillators by a US airline. N Engl J Med.2000;343:1210-1216.Google Scholar
Nichol G, Stiell IG, Laupacis A, Pham B, De Maio VJ, Wells GA. A cumulative meta-analysis of the effectiveness of defibrillator-capable emergency medical services for victims of out-of-hospital cardiac arrest. Ann Emerg Med.1999;34:517-525.Google Scholar
Ewy GA, Ornato JP. 31st Bethesda Conference. J Am Coll Cardiol.2000;35:832-846.Google Scholar
Zipes DP, Wellens HJ. Sudden cardiac death. Circulation.1998;98:2334-2351.Google Scholar
Gratton M, Lindholm DJ, Campbell JP. Public-access defibrillation. Prehosp Emerg Care.1999;3:303-305.Google Scholar
Crewdson J. Code blue: survival in the sky. Chicago Tribune.June 30, 1996;section 2:1-10.Google Scholar
Page RL, Hamdan MH, McKenas DK. Defibrillation aboard a commercial aircraft. Circulation.1998;97:1429-1430.Google Scholar
O'Rourke MF, Donaldson E, Geddes JS. An airline cardiac arrest program. Circulation.1997;96:2849-2853.Google Scholar
House Subcommittee on Aviation: Hearing on FAA implementation of the Aviation Medical Assistance Act of 1998 , 106th Cong, 2nd Sess (2000). Available at: http://www.house.gov/transportation/aviation/06-20-00/06-20-00memo.html. Accessed November 15, 2000.
Federal Aviation Administration. Emergency medical equipment, 66 Federal Register.19028 (2001).Google Scholar
Sapp F. Final Regulatory Evaluation, Final Regulatory Flexibility Determination, Final Unfunded Mandate Assessment, Final Trade Impact Assessment. Washington, DC: Federal Aviation Administration, Office of Aviation Policy, Plans, and Management Analysis; 2001. Publication FAA-2000-7119-395.
Flint P. Uneasy seatmates. Presented at: International Air Transport Association's Aircraft Maintenance '98 Conference and Exhibition; November 3, 1998; Dubai, United Arab Emirates.
Nichol G, Hallstrom AP, Ornato JP. et al. Potential cost-effectiveness of public access defibrillation in the United States. Circulation.1998;97:1315-1320.Google Scholar
Jermyn BD. Cost-effectiveness analysis of a rural/urban first-responder defibrillation program. Prehosp Emerg Care.2000;4:43-47.Google Scholar
Foutz R, Sayre M. Automated external defibrillators in long-term care facilities are cost-effective. Prehosp Emerg Care.2000;4:314-317.Google Scholar
Gold MR, Siegel JE, Russell LB, Weinstein MC. Cost-effectiveness in Health and Medicine. New York, NY: Oxford University Press; 1996.
Hofer S, Berardino F, Smith J, Rubin S. Economic Values for Evaluation of Federal Aviation Administration Investment and Regulatory Decisions. Washington, DC: Federal Aviation Administration, Office of Aviation Policy and Plans; 1998. Publication FAA-APO-98-8.
Rayman RB, Davis JR. Aviation medicine. JAMA.1994;271:1657-1658.Google Scholar
Valenzuela TD, Roe DJ, Cretin S, Spaite DW, Larsen MP. Estimating effectiveness of cardiac arrest interventions. Circulation.1997;96:3308-3313.Google Scholar
Berek K, Schinnerl A, Traweger C. et al. The prognostic significance of coma-rating, duration of anoxia and cardiopulmonary resuscitation in out-of-hospital cardiac arrest. J Neurol.1997;244:556-561.Google Scholar
Thompson RJ, McCullough PA, Kahn JK, O'Neill WW. Prediction of death and neurologic outcome in the emergency department in out-of-hospital cardiac arrest survivors. Am J Cardiol.1998;81:17-21.Google Scholar
Sedgwick ML, Dalziel K, Watson J. et al. Performance of an established system of first responder out-of-hospital defibrillation. Resuscitation.1993;26:75-88.Google Scholar
Weiss JP, Saynina O, McClellan MB, Hlatky MA. Outcomes and costs associated with implantable cardioverter defibrillator use in Medicare patients with life-threatening ventricular arrhythmia. Circulation.2000;102:395.Google Scholar
Nichol G, Stiell IG, Hebert P. et al. What is the quality of life for survivors of cardiac arrest? Acad Emerg Med.1999;6:95-102.Google Scholar
Torrance GW, Furlong W, Feeny D, Boyle M. Multi-attribute preference functions: Health Utilities Index. Pharmacoeconomics.1995;7:503-520.Google Scholar
Gage BF, Cardinalli AB, Owens DK. The effect of stroke and stroke prophylaxis with aspirin or warfarin on quality of life. Arch Intern Med.1996;156:1829-1836.Google Scholar
Pasta DJ, Taylor JL, Henning JM. Probabilistic sensitivity analysis incorporating the bootstrap. Med Decis Making.1999;19:353-363.Google Scholar
Doubilet P, Begg CB, Weinstein MC. et al. Probabilistic sensitivity analysis using Monte Carlo simulation. Med Decis Making.1985;5:157-177.Google Scholar
Skogvoll E, Lindqvist BH. Modeling the occurrence of cardiac arrest as a Poisson process. Ann Emerg Med.1999;33:409-417.Google Scholar
Owens DK, Sanders GD, Harris RA. et al. Cost-effectiveness of implantable cardioverter defibrillators relative to amiodarone for prevention of sudden cardiac death. Ann Intern Med.1997;126:1-12.Google Scholar
Antiarrhythmics versus Implantable Defibrillators (AVID) Investigators. A comparison of antiarrhythmic-drug therapy with implantable defibrillators in patients resuscitated from near-fatal ventricular arrhythmias. N Engl J Med.1997;337:1576-1583.Google Scholar
Graham JD, Thompson KM, Goldie SJ. et al. The cost-effectiveness of air bags by seating position. JAMA.1997;278:1418-1425.Google Scholar
Bureau of Labor Statistics. Occupational Outlook Handbook. Washington, DC: US Dept of Labor, Bureau of Labor Statistics; 2000.
de Vos R, de Haes HC, Koster RW, de Haan RJ. Quality of survival after cardiopulmonary resuscitation. Arch Intern Med.1999;159:249-254.Google Scholar
Eisenberg MS, Bergner L, Hallstrom A. Survivors of out-of-hospital cardiac arrest: morbidity and long-term survival. Am J Emerg Med.1984;2:189-192.Google Scholar
Freeman KD, Isaacs ED, Isaacs SM. Quality of life in survivors one to five years after cardiac arrest. Acad Emerg Med.2001;8:431-432.Google Scholar
Graves JR, Herlitz J, Bang A. et al. Survivors of out of hospital cardiac arrest. Resuscitation.1997;35:117-121.Google Scholar
Roine RO, Kajaste S, Kaste M. Neuropsychological sequelae of cardiac arrest. JAMA.1993;269:237-242.Google Scholar
International Air Transport Association. Corporate Air Travel Survey 1999. London, England: International Air Transport Association; 2000.
SoRelle R. States set to pass laws limiting liability for lay users of automated external defibrillators. Circulation.1999;99:2606-2607.Google Scholar
Pinski SL, Yao Q, Epstein AE. et al. Determinants of outcome in patients with sustained ventricular tachyarrhythmias. Am Heart J.2000;139:804-813.Google Scholar
Kim SG, Hallstrom A, Love JC. et al. Comparison of clinical characteristics and frequency of implantable defibrillator use between randomized patients in the Antiarrhythmics vs Implantable Defibrillators (AVID) trial and nonrandomized registry patients. Am J Cardiol.1997;80:454-457.Google Scholar
Banta HD, Thacker SB. The case for reassessment of health care technology. JAMA.1990;264:235-240.Google Scholar
National Heart, Lung, and Blood Institute. Study launched to test public access defibrillation [press release]. Available at: http://www.nhlbi.nih.gov/new/press/aug22-00.htm. Accessed June 29, 2001.
Air Transport Association of America, Inc. Industry Annual Report 2000. Available at: http://www.air-transport.org/public/2000ap/. Accessed February 20, 2001.
Every N, Weaver W. AEDs: Automatic and advisory trans-chest defibrillation. In: Tacker W, ed. Defibrillation of the Heart ICDs, AEDs, and Manual. St Louis, Mo: Mosby-Year Book Inc; 1994:182-195.
Riegel B. Training nontraditional responders to use automated external defibrillators. Am J Crit Care.1998;7:402-410.Google Scholar
Varon J, Sternbach GL, Marik PE. et al. Automatic external defibrillators. Resuscitation.1999;41:219-223.Google Scholar
Eisenberg MS, Copass MK, Hallstrom AP. et al. Treatment of out-of-hospital cardiac arrests with rapid defibrillation by emergency medical technicians. N Engl J Med.1980;302:1379-1383.Google Scholar
Nichol G, Laupacis A, Stiell IG. et al. Cost-effectiveness analysis of potential improvements to emergency medical services for victims of out-of-hospital cardiac arrest. Ann Emerg Med.1996;27:711-720.Google Scholar
Cardiology Medical Devices and Equipment Violence Health Care Economics, Insurance, Payment Rhythm Disorders War
Groeneveld PW, Kwong JL, Liu Y, et al. Cost-effectiveness of Automated External Defibrillators on Airlines. JAMA. 2001;286(12):1482–1489. doi:10.1001/jama.286.12.1482
Peter W. Groeneveld, MD; Jeanne L. Kwong, MBA; Yueyi Liu, MS; et al Adam J. Rodriguez, MBA; Michael P. Jones, MBA; Gillian D. Sanders, PhD; Alan M. Garber, MD, PhD
Author Affiliations: Center for Primary Care and Outcomes Research (Drs Groeneveld, Sanders, and Garber), Graduate School of Business (Ms Kwong and Mr Rodriguez), and Stanford Biomedical Informatics (Ms Liu), Stanford University, Stanford, Calif; Front Line Strategic Management Consulting, Foster City, Calif (Mr Jones); and Veterans Affairs Palo Alto Health Care System, Palo Alto, Calif (Dr Garber).
Context Installation of automated external defibrillators (AEDs) on passenger aircraft has been shown to improve survival of cardiac arrest in that setting, but the cost-effectiveness of such measures has not been proven.
Objective To examine the costs and effectiveness of several different options for AED deployment in the US commercial air transportation system.
Design, Setting, and Subjects Decision and cost-effectiveness analysis of a strategy of full deployment on all aircraft as well as several strategies of partial deployment only on larger aircraft, compared with a baseline strategy of no AEDs on aircraft (but training flight attendants in basic life support) for a hypothetical cohort of persons experiencing cardiac arrest aboard US commercial aircraft. Estimates for costs and outcomes were obtained from the medical literature, the Federal Aviation Administration, the Air Transport Association of America, a population-based cohort of Medicare patients, AED manufacturers, and the Bureau of Labor Statistics.
Main Outcome Measures Quality-adjusted survival after cardiac arrest; costs of AED deployment on aircraft and of medical care for cardiac arrest survivors.
Results Adding AEDs on passenger aircraft with more than 200 passengers would cost $35 300 per quality-adjusted life-year (QALY) gained. Additional AEDs on aircraft with capacities between 100 and 200 persons would cost an additional $40 800 per added QALY compared with deployment on large-capacity aircraft only, and full deployment on all passenger aircraft would cost an additional $94 700 per QALY gained compared with limited deployment on aircraft with capacity greater than 100. Sensitivity analyses indicated that the quality of life, annual mortality rate, and the effectiveness of AEDs in improving survival were the most influential factors in the model. In 85% of Monte Carlo simulations, AED placement on large-capacity aircraft produced cost-effectiveness ratios of less than $50 000 per QALY.
Conclusion The cost-effectiveness of placing AEDs on commercial aircraft compares favorably with the cost-effectiveness of widely accepted medical interventions and health policy regulations, but is critically dependent on the passenger capacity of the aircraft. Placing AEDs on most US commercial aircraft would meet conventional standards of cost-effectiveness.
Out-of-hospital cardiac arrest claims the lives of approximately 275 000 persons each year in the United States.1,2 Automated external defibrillators (AEDs) improve the low-survival rates from cardiac arrest when operated by trained emergency personnel.3-9 Recent studies10,11 have emphasized the effectiveness of AEDs in improving survival when used by trained laypersons in casinos and commercial aircraft, with survival rates substantially higher than those achieved by emergency responders.12 However, AEDs are costly, in terms of equipment, maintenance, and training, so it is unclear whether they represent an efficient use of health care resources.13,14 Cost-effectiveness analysis can lend insight into which settings are the most strategic for AED deployment.15
Cardiac arrest onboard a passenger aircraft is almost always fatal due to delays in emergency medical care.16 In the hope of improving survival, various airlines have installed AEDs on aircraft since the early 1990s. Deployment of AEDs on Quantas and American Airlines has demonstrated the ability of flight attendants to resuscitate persons who experienced cardiac arrest aboard aircraft.11,17,18 Prompted by initial reports of AED effectiveness, the US Congress passed the Aviation Medical Assistance Act (1998), which directed the Federal Aviation Administration (FAA) to consider requiring AEDs on all passenger aircraft.19 In April 2001, the FAA issued a rule requiring all commercial aircraft with at least 1 flight attendant to carry AEDs by 2004.20 An FAA cost evaluation projected this regulation would cost the airline industry $300 000 per life saved.21 Some industry observers have questioned the appropriateness of this regulatory action.22
We searched the MEDLINE database (1966-2001) using keywords defibrillation, defibrillator, cost, or economic, and found 311 titles, of which 3 were cost-effectiveness analyses of AEDs. Two of these studies, which focused on residential communities,23,24 may contribute to decision making about AED deployment in municipalities and rural areas but do not apply to the diverse settings for which AEDs are now being considered. The only analysis that addressed deployment in a specialized site was by Foutz and Sayre,25 who examined AED cost-effectiveness in chronic-care facilities. To our knowledge, we are the first to report a cost-effectiveness analysis of AED deployment on passenger aircraft.
The purpose of our study was to evaluate the cost-effectiveness of AEDs on US passenger aircraft. We designed a model that captured airline industry and health care costs as well as the improved survival and quality-of-life benefits of AEDs, to estimate the cost per quality-adjusted life-year (QALY) gained by widespread AED deployment on commercial aircraft.
Decision Model
We developed a decision-analytic model to compare several different strategies for AED placement on aircraft. Our model used Markov processes to capture both the immediate costs and benefits of the AED as well as the costs and benefits in the years following cardiac arrest (Figure 1). Following the recommendations of the Panel on Cost-effectiveness in Health and Medicine,26 we took a societal perspective for costs and benefits, discounted at 3% annually. Our study was restricted to costs derived from the US airline industry and health care system. The model was designed to capture all costs and benefits accrued by aircraft cardiac arrest patients until the death of the entire cohort.
We hypothesized that placing AEDs on larger aircraft would be more efficient than deployment on smaller aircraft, because larger aircraft carry a disproportionate number of passenger-hours in the US air transportation system.27 For our base-case, we compared 7 different strategies for AED deployment (Table 1). Because most US flight attendants are trained in basic life support (BLS),21 we assumed that airlines would continue BLS training for flight attendants even if no AEDs were deployed. Thus, for the initial comparison, the lowest cost option A was BLS training for all flight attendants without AED installation. Deployment strategies B and C placed AEDs only on large-capacity (>200 passengers) aircraft. Strategy B assumed that airlines with at least 1 AED-equipped aircraft would train all flight attendants in AED use, while strategy C assumed that airlines could selectively train some flight attendants to use AEDs and designate them to staff AED-equipped aircraft. Strategies D and E had AEDs placed on large-capacity and medium-capacity (>100 passengers) aircraft, while strategy F was full AED deployment on all aircraft with trained flight attendants. Analogous to the training schemes of alternatives B and C, under strategy D all flight attendants would receive AED training, while under strategy E selective training would be used. All flight attendants were trained to operate AEDs in strategy F. As the probability is high of at least 1 health professional onboard any passenger aircraft,28 strategy G assumed full AED deployment with no flight attendant training and relied on physician-passengers to provide treatment in an emergency.
Base-Case Assumptions
Our model followed a hypothetical cohort of patients experiencing cardiac arrest onboard US commercial aircraft during a 12-month period. We assumed aircraft cardiac arrest patients were similar to those in the general population.2 No published data exist on the actual number of cardiac arrests occurring on aircraft. We therefore based the event rate on 627 956 American Airlines flights in 1997-1999.11 This represented a 15% sample of US passenger-hours spent aboard aircraft in the year 2001, according to the FAA's estimates for annual growth.27 The cardiac arrest event rate incorporated both domestic and international flights with US points of origin (Table 2). The cost to passengers not experiencing cardiac arrest was captured elsewhere in the model, either by accounting for program costs to the airlines or for medical care costs to society.
The ability of AEDs to improve survival was estimated from the survival rate measured on American Airlines for 36 cases of cardiac arrest (29 aboard aircraft) treated with AEDs.11 As the baseline rate of survival in the absence of defibrillators is unknown, we estimated it using the logistic regression model of Valenzuela et al,29 with predictor values (eg, time to defibrillation) derived from rural emergency medical systems that have transport times longer than 20 minutes.4,9 The hospital survival rate in the absence of AEDs, assuming a delay in delivery of care, was also abstracted from these rural studies. In our model, AEDs increased both the initial resuscitation rate and the hospital discharge rate after cardiac arrest. Rapid defibrillation can improve hospital survival by preventing the adverse effects of prolonged cessation of circulation that contribute to mortality after initial resuscitation.12,30,31
We assumed that cardiac arrest patients who survived to hospital discharge would be in 1 of 3 health categories: cerebral performance category (CPC)-1: able to function at prearrest level; CPC-2: some cognitive or functional difficulties but able to live independently; or CPC-3/CPC-4: severely impaired, requiring institutional care. These outcomes were obtained from the Heartstart Scotland Project,32 which examined outcomes in 174 survivors of cardiac arrest. The annual mortality of survivors was estimated from the age-adjusted rate observed in 15 152 Medicare patients who had survived to hospital discharge after cardiac arrest or ventricular arrhythmia.33
Airline costs were obtained from the FAA and the Air Transport Association of America. Wages for flight attendants were estimated from Bureau of Labor Statistics data. We assumed that flight attendants would receive BLS and AED instruction following American Heart Association guidelines for duration and frequency of training. Training costs were approximated by calculating the opportunity cost of employee time and airline resources devoted to BLS and AED training.26 Medical costs were derived from published estimates of hospital and medical expenditures after cardiac arrest and from Medicare reimbursement claims33 for 15 152 survivors of cardiac arrest or ventricular arrhythmia (J. P. Weiss, written communication, April 4, 2001). Manufacturers of AEDs provided device costs and maintenance estimates in a telephone survey. We used FAA estimations for volume discounts.21
The quality of life for unimpaired (CPC-1) survivors of cardiac arrest was abstracted from published measures of health care utilities (quality weights) derived from the Health Utilities Index Mark-3 questionnaire, administered a mean (SD) of 9.9 (3.5) months after cardiac arrest.34,35 The utilities for moderate (CPC-2) and severe (CPC-3/CPC-4) impairment after cardiac arrest were estimated from published measurements of similar levels of impairment in stroke survivors.36
We calculated the base-case incremental cost-effectiveness. One-way sensitivity analyses were performed on all variables over specified ranges (Table 2). Pairs of variables that appeared influential and correlated were selected for 2-way sensitivity analyses. Monte Carlo analyses were performed in which every parameter was varied simultaneously over a specified probability distribution. Costs and time variables were assigned log-normal distributions,37 probabilities were assigned logistic distributions,38 and the incidence of cardiac arrest was modeled by the Poisson distribution.39 Variables without a definitive distributional form were assigned the normal distribution, which was subsequently tested in sensitivity analysis. Ten thousand simulations were performed to approximate confidence intervals for the primary results. Models were created and analyses were performed using DATA 3.5 (TreeAge Software Inc, Williamstown, Mass) and Excel 2000 (Microsoft Inc, Redmond, Wash).
Base-Case Analysis
The benefit of AEDs was proportional to the number of person-years covered by each strategy (Table 3). Deploying AEDs on all aircraft (strategy F) would save approximately 33 lives per year (essentially the 17% survival rate found by Page et al11). The average survivor would experience 5.1 QALYs at an incremental cost per QALY of $94 700. Limiting AED deployment to larger aircraft (strategy C) would save fewer lives but would cost only $35 300 per QALY gained.
Sensitivity Analyses
One-way sensitivity analyses identified several influential variables (Figure 2). Among these variables were AED effectiveness in improving resuscitation and hospital survival. A 2-way sensitivity analysis of these factors indicated that if the AED resuscitation rate were less than 30% (base-case value [BCV] = 36%) and hospital survival were less than 45% (BCV = 46%), extending AED coverage to small-capacity aircraft would improve outcomes at a cost exceeding $100 000 per QALY. Conversely, to have a cost of less than $50 000 per QALY regardless of passenger capacity, AEDs would need to resuscitate 50% of persons experiencing cardiac arrest, with 63% of resuscitated patients surviving to hospital discharge. In comparison, AEDs deployed solely on large-capacity aircraft could resuscitate as few as 25% of patients, with an overall survival rate of only 10%, and still yield a cost of less than $50 000 per QALY. A separate 2-way sensitivity analysis indicated that if utility for an unimpaired survivor were greater than 0.9 (BCV = 0.78) and the annual mortality were less than 5% (BCV = 12%), the cost-effectiveness of AEDs would be less than $50 000 per QALY for all types of aircraft. The rate of cardiac arrest on aircraft is also critical to cost-effectiveness—if 300 aircraft cardiac arrests occurred annually instead of the baseline estimate of 200, the incremental cost-effectiveness would be reduced to $26 700, $30 100, and $66 000 per QALY for AEDs on large-capacity, medium-capacity, and small-capacity aircraft, respectively.
Monte Carlo Analyses
Monte Carlo simulation is a method by which the uncertainty of a model's input variables can be used to generate confidence intervals for the model's output.38 Monte Carlo analyses suggested that 95% of simulated cost-effectiveness ratios for AED installation on large-capacity aircraft would be between $11 400 and $74 800 per QALY. Only 14.9% of simulations had incremental cost-effectiveness ratios greater than $50 000 per QALY. The interval for extending deployment to medium-capacity aircraft was $23 000 to $72 100, with 22.3% of the simulations having cost-effectiveness ratios greater than $50 000 per QALY. Finally, the 95% confidence interval for further expanding AED coverage to cover all passenger aircraft was $58 300 to $166 500. Most (99.8%) of these trials had values greater than $50 000 per QALY while 44.2% of trials had values in excess of $100 000 per QALY. None of these boundaries was affected by the choice of modeling distribution (<$5000 per QALY difference) for variables with indeterminate functional form.
Alternative Analyses
A factor not included among our original strategies was the potential elimination of BLS training for flight attendants who staff non–AED-equipped aircraft (strategies A, C, and E) or when physician-passengers would be rescuers (strategy G). When this factor was included via new strategies H, I, J, and K (Table 1), we found that strategy J (placing AEDs on aircraft for use by physician-passengers, but training no flight attendants in BLS or defibrillation) became a viable option at a cost of $45 600 per QALY. The incremental cost-effectiveness for AED deployment on large-capacity and medium-capacity aircraft (with flight attendants trained to perform defibrillation) compared with the physician-passenger strategy was $94 400 per additional QALY. Further expansion of deployment to all aircraft, compared with limiting deployment to large-capacity and medium-capacity aircraft, cost $106 700 per QALY gained. All other strategies were dominated (more costly and less effective) (Figure 3). Additionally, a constraint that was not incorporated in our original strategies was the possibility that airlines would be compelled to offer a single training program to all flight attendants regardless of how many aircraft were equipped with defibrillators. When our model was analyzed with all partial-training strategies removed (C, E, H, and I), the cost-effectiveness of AED deployment on medium-capacity and large-capacity aircraft was $40 800 per QALY, and extending deployment to small-capacity aircraft cost $78 600 per QALY. Finally, when cost and outcome data derived from the Antiarrhythmics Versus Implantable Defibrillator (AVID) trial40,41 were used instead of the community-based Medicare data, the cost-effectiveness of large-capacity aircraft deployment was $52 600 per QALY, extending deployment to medium-capacity aircraft cost $60 300 per QALY, and deployment on small-capacity aircraft cost $135 700 per QALY.
The incremental cost-effectiveness of full AED deployment on commercial aircraft ranges from $35 300 to $94 700 per QALY. The values for deployment on larger aircraft compare favorably with other health care interventions and transportation safety items. For example, a recent study demonstrated that driver-side airbags have a cost-effectiveness of $30 000 per QALY compared with no airbags, and adding passenger-side airbags saves lives at a cost of $76 500 per QALY compared with driver-side airbags alone (values adjusted from published estimates to 2001 dollars).42
Key Variables
The cost-effectiveness of AEDs depends on the rate at which they save lives. However, only a few, small studies have assessed the effectiveness of AEDs in specialized settings such as commercial aircraft. In addition to the work of Page et al,11 O'Rourke et al18 reported the 5-year experience of Quantas Airlines, in which 2 of 27 patients who experienced cardiac arrest eventually survived to hospital discharge. (The American Airlines study may be more representative of AED efficacy on domestic flights, since some Quantas patients were not recognized to be in cardiac arrest but were assumed to be sleeping during long trans-Pacific flights.) Additionally, little is known about survival rates from cardiac arrest in comparable settings prior to AED deployment. The assumption that most patients experiencing cardiac arrest aboard aircraft would not survive in the absence of AEDs is plausible, but it may not hold in other settings. Two-way sensitivity and Monte Carlo analyses of our model demonstrated that even if our assumption of AED effectiveness were overly optimistic or baseline survival overly pessimistic, the cost-effectiveness of AED deployment on large-capacity and medium-capacity aircraft is still likely to cost less than $50 000 per QALY gained.
The incidence of cardiac arrest on aircraft also plays an important role in AED cost-effectiveness. There is a paucity of data on the true incidence rate of cardiac arrest during flight. The Aviation Medical Assistance Act of 1998 required major air carriers to report in-flight deaths over a 1-year period (108 deaths were recorded),19 yet some have speculated that airlines may be reluctant to report deaths.16 The frequency measured by Page et al11 was derived from a 1997-1999 sample representing only 15% of US aircraft passenger-hours flown in the year 2001. Our analysis suggests that a higher event rate would improve the cost-effectiveness of AED deployment.
If airlines could not limit AED training when only a fraction of aircraft were AED-equipped, deployment on large-capacity aircraft only would become an unacceptable (dominated) strategy. Large-capacity aircraft deployment would also be dominated if airlines were able to eliminate AED and BLS training entirely for flight attendants who would not staff AED-equipped aircraft. Currently most airlines have a single health-and-safety training program for flight attendants.43 Creating different tiers of training may not be feasible or may introduce additional costs (eg, staffing shortages or pay differentials) that were not incorporated into this model.
Our analysis has important limitations in quantifying effectiveness. First, the outcomes of rural emergency services may be an imperfect proxy for cardiac arrest outcomes on non–AED-equipped aircraft. However, we found in sensitivity analysis that varying the baseline resuscitation rate from 1% to 10% had no substantial effect on the results. Second, there is incomplete understanding of quality of life after cardiac arrest. Among the studies of quality of life in cardiac arrest survivors,30,31,44-48 only 1 reported preference-based measures (utilities).34 This study may have favored patients who were able to return a survey, and thus may have produced biased estimates. We supplemented these data with utilities derived from patients (stroke survivors) for whom comprehensive data exist on health-related utility with differing degrees of neurological impairment. Further follow-up studies of patients who experienced cardiac arrest on aircraft are needed to better determine whether these patients have better or worse outcomes than cardiac arrest survivors in the general population. Finally, we did not account for the potential benefit that AEDs may provide to the millions of passengers who will not experience a cardiac arrest on an aircraft but who enjoy the intangible benefit of greater security. Nevertheless, this value is likely negligible—a recent passenger survey indicated that the small differences in the flight safety records of major carriers do not influence the choice of airline for the vast majority of US travelers.49
We also note limitations in the measurement of costs. We did not account for additional costs of diverting an aircraft in mid flight to transport a person experiencing cardiac arrest to the nearest hospital. It is possible that onboard AEDs may increase as well as decrease the frequency of emergency medical diversions. Additionally, attorney and court costs or savings from increased or decreased litigation were excluded. However, Good Samaritan legislation may protect users of AEDs from legal liability.50 Finally, the use of Medicare data for costs and outcomes potentially biased the results, as this older population may have higher health costs and worse outcomes.51 We age-adjusted our mortality rate; the values we obtained were comparable with those observed in the community-based Heartstart Scotland Project.32 An alternative source of economic and outcomes data is the AVID trial—using these data increases the cost per QALY of all AED deployment options. Nevertheless, this result may also be biased, as the use of expensive medical technologies by cardiac arrest patients in the AVID trial was higher than in the general population.52
Implications and Recommendations
This study suggests that widespread deployment of AEDs on commercial aircraft is cost-effective when compared with many other health or safety interventions that are generally acceptable. This assessment of cost-effectiveness is robust, particularly for AED installation on large-capacity aircraft—even simultaneous changes in many of the key parameters do not raise the cost above $50 000 per QALY for AED placement. Conversely, BLS training of flight attendants in the absence of AEDs is not cost-effective. The economic benefit of extending AED deployment to small-capacity aircraft is less certain. Our results suggest that careful monitoring of the costs and effectiveness of AEDs is warranted as these devices are deployed on small-capacity aircraft over the next 3 years. Eventual reevaluation of the economic consequences of current policy compared with other safety-related programs would be appropriate.53
Determining optimal device deployment locations and identifying AED training candidates are significant challenges for public access defibrillation programs. Cost will be an essential factor in these decisions due to sizeable device and training expenses as well as the infrequency and unpredictability of cardiac arrests. Policymakers will face multiple decisions regarding AED deployment in diverse settings. The ongoing Public Access Defibrillation Trial may address some of the uncertainties in community deployment.54 However, other settings have special characteristics that substantially influence the costs and likelihood of survival. Our analysis, while not directly applicable beyond passenger aircraft, can guide the construction of similar economic analyses.
A program of placing AEDs on large-capacity passenger aircraft readily meets conventional standards of cost-effectiveness. Even deployment on medium-capacity passenger aircraft attains generally accepted levels of cost-effectiveness. The cost-effectiveness of deployment on smaller aircraft is less certain. Careful monitoring of the costs and consequences of total aircraft AED deployment is warranted to ensure efficient use of safety-related resources in the airline industry.


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Rønø är en ö i Danmark.   Den ligger i Region Själland, i den östra delen av landet,  km väster om Köpenhamn.

Källor

Öar i Region Själland
Holbæks kommun

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text:
Q: Grouping with in minute SQL This is a very typical requirement, I tried to code the group by but isn't working
RegDate                    signupdate           channel ID      product
09/05/2016 23:52:34 09/05/2016 23:55:06 Mobile     1            apple
09/05/2016 23:52:32 09/05/2016 23:52:45 Mobile     2            mango
09/05/2016 23:52:16                     Mobile     3            mango
09/05/2016 23:52:49                     Mobile     4            banana
09/05/2016 23:52:50                     Mobile     5            banana
09/05/2016 23:52:50 09/05/2016 15:52:45 Mobile     5            Kiwi

Output
Regdate       min     No.of Regs   No.of Signups  channel Product
09/05/2016   23:52      1           1              mobile  apple
09/05/2016   23:52      2           1              mobile  mango
09/05/2016   23:52      2                          mobile  banana
09/05/2016   23:52      1                          mobile  Kiwi

My current query:
select  SUBSTR(TO_CHAR(regdate, 'HH24:MI:SS'),1,5),count(distinct ID),
       channel, product
from glance_REG_act_Prod_samp
group by SUBSTR(TO_CHAR(regdate, 'HH24:MI:SS'),1,5), source, reg_product

A: I think you need the date in the group by, but not the seconds.  Does this do what you want?
select TO_CHAR(regdate, 'YYYY-MM-DD HH24:MI'), source, reg_product,
       count(distinct ID)
from glance_REG_act_Prod_samp
group by TO_CHAR(regdate, 'YYYY-MM-DD HH24:MI'), source, reg_product;

Note:  You should use COUNT(*) unless duplicates of ID really exist.

A: I think this is what you're after:
with sample_data as (select to_date('09/05/2016 23:52:34', 'dd/mm/yyyy hh24:mi:ss') regdate, to_date('09/05/2016 23:55:06', 'dd/mm/yyyy hh24:mi:ss') signupdate, 'Mobile' channel, 1 id, 'apple' product from dual union all
                     select to_date('09/05/2016 23:52:32', 'dd/mm/yyyy hh24:mi:ss') regdate, to_date('09/05/2016 23:52:45', 'dd/mm/yyyy hh24:mi:ss') signupdate, 'Mobile' channel, 2 id, 'mango' product from dual union all
                     select to_date('09/05/2016 23:52:16', 'dd/mm/yyyy hh24:mi:ss') regdate, null signupdate, 'Mobile' channel, 3 id, 'mango' product from dual union all
                     select to_date('09/05/2016 23:52:49', 'dd/mm/yyyy hh24:mi:ss') regdate, null signupdate, 'Mobile' channel, 4 id, 'banana' product from dual union all
                     select to_date('09/05/2016 23:52:50', 'dd/mm/yyyy hh24:mi:ss') regdate, null signupdate, 'Mobile' channel, 5 id, 'banana' product from dual union all
                     select to_date('09/05/2016 23:52:50', 'dd/mm/yyyy hh24:mi:ss') regdate, to_date('09/05/2016 15:52:45', 'dd/mm/yyyy hh24:mi:ss') signupdate, 'Mobile' channel, 6 id, 'kiwi' product from dual)
select   to_char(regdate, 'dd/mm/yyyy') regdate,
         to_char(regdate, 'hh24:mi') min,
         count(*) num_of_regs,
         count(case when signupdate >= regdate then 1 end) num_signups,
         channel,
         product
from     sample_data
group by to_char(regdate, 'dd/mm/yyyy'),
         to_char(regdate, 'hh24:mi'),
         channel,
         product
order by product;

REGDATE    MIN   NUM_OF_REGS NUM_SIGNUPS CHANNEL PRODUCT
---------- ----- ----------- ----------- ------- -------
09/05/2016 23:52           1           1 Mobile  apple
09/05/2016 23:52           2           0 Mobile  banana
09/05/2016 23:52           1           0 Mobile  kiwi
09/05/2016 23:52           2           1 Mobile  mango

Note that I've assumed that the id column is unique and that the fact your last row had id = 5 was a typo.
I have also assumed that the reason why the output for the kiwi product didn't have a signup count available is because the signup date was before the registration date. You didn't explain the logic behind that, so I don't know if that was a typo in your expected output or not. You should be able to amend my query to output whichever results you require, though (for example case when signupdate is not null then 1 end perhaps?).
Also, if you want to display blanks instead of 0, that's a simple CASE / DECODE to change the output to put null instead of 0; your choice.
As a complete aside, you're doing: SUBSTR(TO_CHAR(regdate, 'HH24:MI:SS'),1,5) ... why? You're creating a string from the date and then shortening it. Why wouldn't you just create the string from the date in the format you desire? E.g. to_char(regdate, 'hh24:mi')

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DRS Technologies has introduced new rugged tablet namely the Armor X10gx that ideal for mobile worker. The tablet is made in magnesium alloy chassis that meet MIL-STD-810G standard, rated IP67, and certified for use in rail and port facilities, transportation, public safety, and other areas. The Armor X10gx tablet is water resistant that capable of up to 1 meter, dust-proof, and shock-proof. The DRS Armor X10gx mobile machine is boasts a 1.2GHz Intel Core 2 Duo SU9300 processor, 2GB of memory (up to 4GB), a 64/80/160GB solid state drive, and an SD card reader. Rugged Armor X10gx is sports a 10.4-inch LCD display with resolution of 1024 x 768 pixels and support for resistive touch input and digitizer pen, HDMI, Wi-Fi 802.11a/b/g/n, Bluetooth 2.0 + EDR, a fingerprint reader, and optional 3G and GPS module. Dimensions of Armor X10gx rugged tablet are 290 x 218 x 45 mm with weight about 2.2 kg. No word on pricing but it will be start shipping on September 15.


text:
Q: Unable to start ws02 application server on Windows - error "The system cannot find the batch label specified - commandLifecycle" I downloaded wso2 application server 5.0.0.  I placed it on my windows server and attempted to execute wso2server.bat --run.  When I do that, I receive this error:
The system cannot find the batch label specified - commandLifecycle
If I look in the wso2server.bat file, I see that the commandLifecycle label doesn't exist.
Has anyone else run into this same issue?
Edit: I just tried running 4.1.2 and I did not have the same problem.

A: I just run the shell: wso2server.bat without the parameter [--run] and it start ok.


text:
WASHINGTON, DC - DECEMBER 05: Speaker of the House Nancy Pelosi (D-CA) announced that the House will proceed with articles of impeachment against President Donald Trump at the Speaker's Balcony in the U.S. Capitol December 05, 2019 in Washington, DC. (Photo: Getty)
House Passes Police Reform Bill Amid Partisan Deadlock After Sen. Tim Scott's Senate GOP Bill Fails
by Dongyoon ShinJune 28, 2020, 6:34 pmJune 28, 2020, 6:34 pmJune 28, 2020, 6:34 pmCongress, Daily Digest, News, News Feed >
House of Representatives passed a police reform bill led by Democrats on Thursday by 236-181, month after George Floyd's death.
A day earlier, Senate Democrats had successfully prevented Republicans' police reform bill, led by Sen. Tim Scott (R-South Carolina), which failed to gain 60 votes it needed to advance for an open debate.
Key differences between the two parties' respective proposals were evident.
Democratic bill has a strong emphasis on amending standards on the federal level, requiring officers to wear body cameras and prohibiting chokeholds.
"We don't paint all police with the same brush," Speaker Nancy Pelosi (D-California) said. "But, for those who need to be painted with that brush, we need to take the action contained in this bill."
Although seemingly aligning with Democrats' plan, the Republican bill doesn't make as big changes Democrats call for.
The Republican bill would incentivize states and local governments to implement changes, instead of raising a national standard. It also doesn't include an outright prohibition on officers using chokeholds.
"Tim Scott's bill is a half-assed bill that doesn't do what we should be doing, which is doing honest police reform," Sen. Mazie Hirono (D-Hawaii) commented.
Following the news of Republican's plan failing in the Senate, President Donald Trump was philosphical.
"If nothing happens with it, it's one of those things," Trump said. "We have different philosophies."
Democrats Donald Trump George Floyd GOP Nancy Pelosi Police Reform
Article by Dongyoon Shin


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The Compact 3.8 Baby Hi-Capa pistol features a metal frame, and adjustable hop-up. Also, included is a TSD 30-day Warranty.