Single Flight Research Articles

Reduced-Risk Management ofRhagoletis cerasiFlies (Host RacePrunus) in Combination with a Preliminary Phenological Model

Seasonal flight activity of Rhagoletis cerasi (L.) (Diptera: Tephritidae) adults was monitored using yellow sticky traps at sweet cherry orchards under different management regimes in Bursa, northwestern Turkey, during 1997–1998. In the reduced-risk backyard orchards, soil ploughing in the fall or spring to destroy the pupae was combined with a single application of an insecticide, while conventionally managed orchards received six to seven insecticide applications for controlling adults. Traps in commercial orchards caught significantly fewer adults than those in reduced-risk backyard orchards. Levels of cherry fruit fly fruit damage were very low (0.1%) in commercial orchards, whereas infestation rates averaged 2.2% in reduced-risk orchards. A preliminary phenology model was developed for optimal timing of insecticide applications based on air temperature summations since 1 February. In the reduced-risk backyard orchards, the first flies were captured between 25 May and 2 June, corresponding to an average degree-day (DD) accumulation of 582.50 ± 10.50 DD at an altitude of 150 m. However, first adult emergence at 1170 m was recorded between 6 and 14 June, averaging 667.50 ± 14.50 DD. Adult emergence exhibited bimodal peaks in a single flight at low altitude but there was a single peak at high altitude sites. Total adult flight period averaged 459 ± 29.50 and 649 ± 25.50 DD at low and high altitude sites, respectively. Our prediction model suggests that the optimum spray-window for a single insecticide application occurs between 577.70 and 639.40 DD at 150 m and between 780.90 and 848.60 DD at 1170 m.

Nocturnal migration of dragonflies over the Bohai Sea in northern China

Abstract 1. A sudden increase and subsequent sharp decrease of catches of dragonflies in a searchlight trap, with Pantala flavescens Fabricius (Odonata: Libellulidae) predominating, observed at Beihuang Island in the centre of the Bohai Gulf, in 2003 and 2004, indicated a seasonal migration of these insects over the sea during the night in China. The movements were associated with the onset of fog.2. Simultaneous radar observations indicated that the nocturnally migrating dragonflies generally flew at altitudes of up to 1000 m above sea level, with high density concentrations at about 200–300 or 500 m; these concentrations were coincident with the temperature inversion.3. During early summer, the dragonflies oriented in a downwind direction, so that the displacement direction varied between different altitudes. In contrast, during late summer, the dragonflies were able to compensate for wind drift, even headwind drift, so as to orient south‐westward no matter how the wind changed, and thus the displacement direction was towards the south‐west.4. The duration of flight, estimated from the variation of area density derived from radar data and hourly catches in the searchlight trap through the night, was about 9–10 h. The displacement speed detected using radar was ≈5–11 m s−1. Therefore, the dragonflies might migrate 150–400 km in a single flight.5. The dragonflies were thought to originate in Jiangsu province and they migrated into north‐east China to exploit the temporary environment of paddy fields in early summer. Their offspring probably migrated back south during late summer and autumn.

An experimental investigation of wave measurements using a dual‐beam interferometer: Gulf Stream as a surface wave guide

A dual‐beam interferometric synthetic aperture radar measures remotely two radial components of the ocean surface current from a single flight pass. Combining two passes over the same area, all three orthogonal components of the surface velocity can be retrieved. An experiment is conducted near the Gulf Stream (GS) boundary. A sharp change of the surface velocity of about 1 m/s over a 500 m lateral distance is measured. The wind and wave condition is dominated by a 14‐s swell system and low wind velocity. The wave variance inside GS is about twice the wave variance outside the GS in the present data set. The difference in the wave variance is considerably higher than that can be expected from wave‐current interaction. An ocean current system with strong shears such as the GS is a wave guide and can trap waves with the right combinations of wavelengths and propagation directions. Numerical calculations suggest that the wave properties of the data set may satisfy the conditions of wave trapping by the GS. The standing wave pattern on the GS side of the sharp velocity front, indicative of the long swell bouncing off the current front, also offers support for the wave guide hypothesis. In this respect, the Gulf Stream can be considered the nature's hydraulic breakwater that can attenuate about 50% of the incident wave energy generated by storms. Its role in protecting the U.S. coastlines in the Atlantic Ocean cannot be overstated.

Post-buckled precompressed piezoelectric flight control actuator design, development anddemonstration

This paper describes a new class of flight control actuators using post-buckledprecompressed (PBP) piezoelectric elements. These actuators are designed to producesignificantly higher deflection and force levels than conventional piezoelectric actuatorelements. Classical laminate plate theory (CLPT) models are shown to workvery well in capturing the behavior of the free, unloaded elements. A new hightransverse deflection model which employs nonlinear structural relations is shown tosuccessfully predict the performance of the PBP actuators as they are exposed tohigher and higher levels of axial force, which induces post-buckling deflections. Aproof-of-concept empennage assembly and actuator were fabricated using theprinciples of PBP actuation. A single grid-fin flight control effector was driven by a3.5′′ (88.9 mm) long piezoceramic bimorph PBP actuator. By using the PBP configuration,deflections were controllably magnified 4.5-fold with excellent correlation between theoryand experiment. Quasi-static bench testing showed deflection levels in excess of ± 6° at rates exceeding 15 Hz. The new solid state PBP actuator was shown to reduce the partcount with respect to conventional servoactuators by an order of magnitude. Powerconsumption dropped from 24 W to 100 mW, weight was cut from 108 to 14 g, slop went from1.6° to0.02° and current draw went from 5 A to 1.4 mA. The result was that the XQ-138 subscale UAVfamily experienced nearly a 4% reduction in operating empty weight via the switch fromconventional to PBP actuators, while in every other measure gross performance wassignificantly enhanced.

Flight‐oogenesis syndrome in a blood‐sucking bug: Biochemical aspects of lipid metabolism

Lipophorin (Lp), either labeled in diacylglycerol moiety with [(3)H]-Palmitic acid or in phospholipid moiety with (32)Pi, was injected into Rhodnius prolixus females. Insects were induced to flight for different times. In just a few minutes of flight, the transfer of radioactivity to ovaries decreased, accompanied by its increase to flight muscles. After one hour of flight, Lp density was higher (1.132 g/mL) than before flight (1.116 g/mL). Lp purified from insects after flight was analyzed by gel filtration chromatography and a polyacrylamide gel pore limit electrophoresis. Both analyses demonstrated a decrease in Lp molecular mass after flight but no changes in apoLp-III amounts were observed. Time-course experiments showed that only 30 min of flight are required for the detection of changes in Lp density and molecular mass. About the same time of rest is necessary for Lp density and molecular mass to return to the baseline value. The lipid content from Lp particles, determined by high-performance thin-layer chromatography (HPTLC), showed a decrease in total lipids after flight. At the same time, an increase of many classes of lipids was observed in flight muscles except for triacylglycerol, which was reduced. The increase of flight muscle lipids was accompanied by a decrease of the ovaries lipid content. The insects subjected to daily exhaustive flight showed a significant decrease in total number of eggs produced. But insects subjected to a single exhaustive flight showed only a small reduction in total number of eggs. Lp density variation during the flight activity of Rhodnius prolixus females is discussed in association with physiological events such as oogenesis.

Nutritional value of floral nectar sources for flight in the parasitoid wasp, Cotesia glomerata

Abstract. This study investigates the feeding of the parasitoid Cotesia glomerata on the floral nectar of Anethum graveolens and Origanum vulgare and evaluates the nutritional value of these food sources for increasing flight capacity. A significantly higher proportion of females are observed feeding on A. graveolens immediately after being released onto the floral nectar plants compared with those of the group released onto O. vulgare, although female wasps from both groups spent a similar period of time feeding on both nectar sources and there is no significant difference in their body weight increase. Laboratory tests on computer‐linked flight mills demonstrate that adult feeding significantly influences flight capacity, as defined by the number of flights, the longest single flight and the total distance flown during a given period of time, in female wasps but not in males, albeit the extent of influence varying with the type of food sources. After ad libitum feeding on the floral nectar of A. graveolens, female wasps perform flight activity as well as those feeding on honey, which is superior to those feeding on sucrose, in all the measured parameters. Feeding on the floral nectar of O. vulgare has a similar effect to feeding on the extrafloral nectar of Vicia faba and significantly increases the total distance flown but not the number of flights or the longest single flight. Feeding on sucrose does not increase flight capacity in the parasitoids beyond those having access to water only. The findings of this study suggest that judicious selection of floral nectar plants and habitat manipulation might play a key role in the biological control of pest insects.

Ancient trans-Atlantic flight explains locust biogeography: molecular phylogenetics ofSchistocerca

The desert locust (Schistocerca gregaria) has been an important agricultural pest at least since biblical times. Although the ecology, physiology and behaviour of this insect species have been well characterized, its biogeographical origins and evolutionary history are more obscure. Schistocerca gregaria occurs throughout Africa, the Middle East and Western Asia, but all other species in the genus Schistocerca are found in the New World. Because S. gregaria has the capacity for extreme long-distance movement associated with swarming behaviour, dispersal may have played an important role in determining current distribution patterns. Some authors have argued that S. gregaria is the product of an eastward trans-Atlantic dispersal from North America to Africa; others consider it more likely that the New World taxa are the product of westward dispersal from Africa. Here, we present a mitochondrial DNA phylogeny of Schistocerca species that supports the monophyly of New World species (including the Galapagos endemic Halmenus) relative to S. gregaria. In concert with observed patterns of molecular divergence, and in contrast to previous morphological studies, our analysis indicates a single trans-Atlantic flight from Africa to South America, followed by extensive speciation and ecological divergence in the New World.

3-D microphysical model studies of Arctic denitrification: comparison with observations

Abstract. Simulations of Arctic denitrification using a 3-D chemistry-microphysics transport model are compared with observations for the winters 1994/95, 1996/97 and 1999/2000. The model of Denitrification by Lagrangian Particle Sedimentation (DLAPSE) couples the full chemical scheme of the 3-D chemical transport model, SLIMCAT, with a nitric acid trihydrate (NAT) growth and sedimentation scheme. We use observations from the Microwave Limb Sounder (MLS) and Improved Limb Atmospheric Sounder (ILAS) satellite instruments, the balloon-borne Michelsen Interferometer for Passive Atmospheric Sounding (MIPAS-B), and the in situ NOy instrument on-board the ER-2. As well as directly comparing model results with observations, we also assess the extent to which these observations are able to validate the modelling approach taken. For instance, in 1999/2000 the model captures the temporal development of denitrification observed by the ER-2 from late January into March. However, in this winter the vortex was already highly denitrified by late January so the observations do not provide a strong constraint on the modelled rate of denitrification. The model also reproduces the MLS observations of denitrification in early February 2000. In 1996/97 the model captures the timing and magnitude of denitrification as observed by ILAS, although the lack of observations north of ~67° N in the beginning of February make it difficult to constrain the actual timing of onset. The comparison for this winter does not support previous conclusions that denitrification must be caused by an ice-mediated process. In 1994/95 the model notably underestimates the magnitude of denitrification observed during a single balloon flight of the MIPAS-B instrument. Agreement between model and MLS HNO3 at 68 hPa in mid-February 1995 is significantly better. Sensitivity tests show that a 1.5 K overall decrease in vortex temperatures, or a factor 4 increase in assumed NAT nucleation rates, produce the best statistical fit to MLS observations. Both adjustments would be required to bring the model into agreement with the MIPAS-B observations. The agreement between the model and observations suggests that a NAT-only denitrification scheme (without ice), which was discounted by previous studies, must now be considered as one mechanism for the observed Arctic denitrification. The timing of onset and the rate of denitrification remain poorly constrained by the available observations.

Cause of winter gravity wave spectrum saturation

This paper utilizes horizontal velocity measurements observed from 19 chaff rockets and nearly simultaneous temperature measurements collected from 19 falling sphere rockets to study the cause of winter gravity wave spectrum saturation. Results suggest that strong horizontal velocity shears larger than 0.04 s −1 are observed to be present at various heights near the winter mesopause. On one single chaff rocket flight, an extremely strong horizontal velocity shear as high as 0.33 s −1 is observed at 87.4 km and is believed to be the strongest value ever measured in the mesosphere. These strong horizontal velocity shears, together with Brunt-Vaisala frequency squared obtained from the temperature profile, act collectively to yield two dynamical instability regions of Richardson number smaller than 1/4, suggesting that the saturated gravity wave spectrum observed by the chaff rockets in winter is a result of dynamical instability.

Calculation of odour emissions from aircraft engines at Copenhagen Airport

In a new approach the odour emissions from aircraft engines at Copenhagen Airport are calculated using actual fuel flow and emission measurements (one main engine and one APU: Auxiliary Power Unit), odour panel results, engine specific data and aircraft operational data for seven busy days. The calculation principle assumes a linear relation between odour and HC emissions. Using a digitalisation of the aircraft movements in the airport area, the results are depicted on grid maps, clearly reflecting aircraft operational statistics as single flights or total activity during a whole day. The results clearly reflect the short-term temporal fluctuations of the emissions of odour (and exhaust gases). Aircraft operating at low engine thrust (taxiing, queuing and landing) have a total odour emission share of almost 98%, whereas the shares for the take off/climb out phases (2%) and APU usage (0.5%) are only marginal. In most hours of the day, the largest odour emissions occur, when the total amount of fuel burned during idle is high. However, significantly higher HC emissions for one specific engine cause considerable amounts of odour emissions during limited time periods. The experimentally derived odour emission factor of 57 OU/mg HC is within the range of 23 and 110 OU/mg HC used in other airport odour studies. The distribution of odour emission results between aircraft operational phases also correspond very well with the results for these other studies. The present study uses measurement data for a representative engine. However, the uncertainties become large when the experimental data is used to estimate the odour emissions for all aircraft engines. More experimental data is needed to increase inventory accuracy, and in terms of completeness it is recommended to make odour emission estimates also for engine start and the fuelling of aircraft at Copenhagen Airport in the future.

Multiple nuptial flights, sperm transfer and the evolution of extreme polyandry in honeybee queens

The honeybee, Apis mellifera , has an extremely polyandrous mating system, which often involves multiple nuptial flights by its queens. To understand the evolution of extreme polyandry, we investigated the cost of multiple nuptial flights in relation to potential benefits. We analysed, with eight DNA microsatellite loci, the paternity of worker offspring of naturally mated queens. Queens that were restricted to one nuptial flight, but may have taken additional nuptial flights if allowed to do so, had significantly fewer matings than queens that started oviposition after a single nuptial flight. Furthermore, the number of sperm stored in a spermatheca increased significantly with the number of matings. We suggest that queens adjust their nuptial flight frequencies according to their mating success in their previous nuptial flights. The number of copulations seems to serve as a signal for the initiation of oviposition. In the light of these findings, we reconsider and discuss the significance of the sperm limitation hypothesis for the evolution of extreme polyandry in A. mellifera .

CROSSING THE ULTIMATE ECOLOGICAL BARRIER: EVIDENCE FOR AN 11 000-KM-LONG NONSTOP FLIGHT FROM ALASKA TO NEW ZEALAND AND EASTERN AUSTRALIA BY BAR-TAILED GODWITS

Populations of the Bar-tailed Godwit (Limosa lapponica; Scolopacidae) embark on some of the longest migrations known among birds. The baueri race breeds in western Alaska and spends the nonbreeding season a hemisphere away in New Zealand and eastern Australia; the menzbieri race breeds in Siberia and migrates to western and northern Australia. Although the Siberian birds are known to follow the coast of Asia during both migrations, the southern pathway followed by the Alaska breeders has remained unknown. Two questions have particular ecological importance: (1) do Alaska godwits migrate directly across the Pacific, a distance of 11 000 km? and (2) are they capable of doing this in a single flight without stopping to rest or refuel? We explored six lines of evidence to answer these questions. The distribution of resightings of marked birds of the baueri and menzbieri races was significantly different between northward and southward flights with virtually no marked baueri resighted along the Asian mainland during southward migration. The timing of southward migration of the two races further indicates the absence of a coastal Asia route by baueri with peak passage of godwits in general occurring there a month prior to the departure of most birds from Alaska. The use of a direct route across the Pacific is also supported by significantly more records of godwits reported from within a direct migration corridor than elsewhere in Oceania, and during the September to November period than at other times of the year. The annual but rare occurrence of Hudsonian Godwits (L. haemastica) in New Zealand and the absence of their records along the Asian mainland also support a direct flight and are best explained by Hudsonian Godwits accompanying Bar-tailed Godwits from known communal staging areas in Alaska. Flight simulation models, extreme fat loads, and the apparent evolution of a wind-selected migration from Alaska further support a direct, nonstop flight. Atravesando la Barrera Ecológica Final: Evidencia de un Vuelo sin Escala de 11 000 km de Longitud desde Alaska a Nueva Zelanda y el Este de Australia por Limosa lapponica Resumen. Las poblaciones de Limosa lapponica (Scolopacidae) se embarcan en una de las migraciones más largas conocidas para aves. La raza baueri cría en el oeste de Alaska y pasa la estación no reproductiva a un hemisferio de distancia en Nueva Zelanda y el este de Australia; la raza menzbieri cría en Siberia y migra hacia el oeste y el norte de Australia. Aunque se sabe que las aves de Siberia siguen la costa de Asia durante ambas migraciones, la ruta meridional que siguen las aves reproductivas de Alaska ha permanecido desconocida. Dos preguntas tienen particular importancia ecológica: (1) ¿las aves de Alaska migran directamente a través de Pacífico, a lo largo de 11 000 km? y (2) ¿son capaces de hacerlo en un único vuelo sin parar a descansar y reabastecerse? Exploramos seis líneas de evidencia para responder a estas preguntas. La distribución de avistamientos de aves marcadas de las razas baueri y menzbieri fue significativamente diferente entre vuelos hacia el norte y el sur, sin que hubiera prácticamente un solo avistamiento de individuos marcados de baueri a lo largo del continente asiático durante la migración hacia el sur. El período de la migración hacia el sur de ambas razas indica la ausencia de una ruta costera asiática para baueri, con un pico en el paso de las aves ocurriendo allí un mes antes de la partida de la mayoría de las aves desde Alaska. El uso de una ruta directa a través del Pacífico también está avalado por un número significativamente mayor de aves reportadas para un corredor migratorio directo que para cualquier otro lugar de Oceanía, y para el período entre septiembre y noviembre que para otros momentos del año. La presencia anual, aunque rara, de L. haemastica en Nueva Zelanda y la ausencia de registros a lo largo del continente asiático también avalan la posibilidad de un vuelo directo y se explican mejor por el hecho de que L. haemastica acompaña a L. lapponica desde áreas de escala comunes en Alaska. Evidencia complementaria de un vuelo directo sin escalas está dada por modelos de simulación de vuelo, la gran acumulación de grasa en las aves y la aparente evolución de una migración seleccionada por el viento.

FLIGHT SPEEDS OF NORTHERN PINTAILS DURING MIGRATION DETERMINED USING SATELLITE TELEMETRY

Speed (km/hr) during flight is one of several factors determining the rate of migration (km/ day) and flight range of birds. We attached 26-g, back-mounted satellite-received radio tags (platform transmitting terminals; PTTs) to adult female Northern Pintails (Anas acuta) during (1) midwinter 2000-2003 in the northern Central Valley of California, (2) fall and winter 2002-2003 in the Playa Lakes Region and Gulf Coast of Texas, and (3) early fall 2002-2003 in south-central New Mexico. We tracked tagged birds after release and, in several instances, obtained multiple locations during single migratory flights (flight paths). We used data from 17 PTT- tagged hens along 21 migratory flight paths to estimate groundspeeds during spring ( n 5 19 flights) and fall ( n 5 2 flights). Pintails migrated at an average groundspeed of 77 6 4 (SE) km/hr (range for individual flight paths 5 40-122 km/hr), which was within the range of estimates reported in the literature for migratory and local flights of waterfowl (42-116 km/hr); further, groundspeed averaged 53 6 6 km/hr in headwinds and 82 6 4 km/hr in tailwinds. At a typical, but hypothetical, flight altitude of 1,460 m (850 millibars standard pressure), 17 of the 21 flight paths occurred in tailwinds with an average airspeed of 55 6 4 km/hr, and 4 occurred in headwinds with an average airspeed of 71 6 4 km/hr. These adjustments in airspeed and groundspeed in response to wind suggest that pintails migrated at airspeeds that on average maximized range and conserved energy, and fell within the range of expectations based on aerodynamic and energetic theory. Received 19 November 2004, accepted 6 September 2005.

Genotoxicity testing on the international space station: Preparatory work on the SOS-LUX test as part of the space experiment TRIPLE-LUX

Harmful environmental factors – namely ionizing radiation – will continue to influence future manned space missions. The Radiation Biology Unit at the German Aerospace Center (DLR) develops cellular monitoring systems, which include bacterial and mammalian cell systems capable of recognizing DNA damage as a consequence of the presence of genotoxic conditions. Such a bioassay is the SOS-LUX test, which represents the radiobiological part of the German space experiment “Gene, immune and cellular responses to single and combined space flight conditions (TRIPLE-LUX)” which has been selected by the IDI/USRA Peer Review Panel for NASA/ESA to be performed on the International Space Station (ISS). It will supply basic information on the genotoxic response to radiation applied in microgravity. The biological end-point under investigation will depend on the bacterial SOS response brought about by genetically modified bacteria that are transformed with the pSWITCH plasmid (constructed from the plasmids pPLS-1 and pGFPuv). The luminescent/fluorescent bioassay SWITCH (SWITCH: Salmonella Weighting of Induced Toxicity Cyto/GenoTox for Human Health) as successor of the SOS-LUX test for rapid toxicity (genotoxicity and cytotoxicity) testing, makes use of two sensing and reporting systems for the two biological endpoints under investigation: the SOS-LUX test and the LAC- Fluoro test. The SWITCH plasmid carries the promoterless lux operon of Photobacterium leiognathi as reporter element under the control of the DNA-damage-dependent SOS promoter of ColD as sensor element (for genotoxicity testing) and the sequences for a hybrid protein consisting of β-galactosidase and GFPuv of Aequorea victoria as reporter element under the control of the (in Salmonella constitutively active) LAC promoter of Escherichia coli as sensor element (for cytotoxicity testing). The system has worked properly for terrestrial applications during the first experiments. Experiments using X-rays and UV radiation of various qualities (from UVC to UVA) have given insights into cellular mechanisms relevant for estimation of health risks, resulting from exposure of astronauts to the extraordinary radiation environment of space.

An Axial-Flow Cyclone for Aircraft-Based Cloud Water Sampling

Abstract A new aircraft-based cloud water collection system has been developed to provide samples of cloud water for chemical analysis. The collection system makes use of centrifugal separation in an axial-flow cyclone to remove cloud drops from the airstream. An automated sample storage system allows up to seven independent samples to be obtained during a single research flight. The entire collection system is housed in a Particle Measurement Systems (PMS) canister to permit the collector to be used on a range of research aircraft without extensive modification to the collector or the aircraft structure. Computational fluid dynamics (CFD) analysis was used extensively throughout the development of the new collector for component design and to predict internal flow dynamics. CFD-based cloud drop trajectory simulations provided an estimate of collection efficiency as a function of drop size. Based on the numerical modeling, the 50% cut diameter was predicted to be 8 μm. Through a quantitative laboratory calibration using fluorescein-tagged monodisperse drops, CFD predictions of drop deposition patterns in the interior of the axial-flow cyclone were verified. The numerical and experimental evaluations were performed to ensure that the population of collected cloud drops is well characterized. Initial flight testing of the system occurred during the Dynamics and Chemistry of Marine Stratocumulus, Phase II (DYCOMS-II) field project in July 2001. Although the major components of the prototype collection system operated as expected during flight testing, sample collection rates were lower than expected because of the inefficient removal and storage of cloud water collected in the axial-flow cyclone. Actual sample collection rates ranged between 0.1 and 1.2 mL min−1.

Microlocal Analysis of Synthetic Aperture Radar Imaging

We consider Synthetic Aperture Radar (SAR) in which backscattered waves are measured from locations along a single flight path of an aircraft. Emphasis is on the case where it is not possible to form a beam with the radar. The article uses a scalar linearized mathematical model of scattering, based on the wave equation. This leads to a forward (scattering) operator, which maps singularities in the coefficient of the wave equation (viewed as a singular perturbation about a constant coefficient) to singularities in the scattered wave field. The goal of SAR is to recover a picture of the singular support of the coefficient, i.e., an a image of the underlying terrain. Traditionally, images are produced by “backprojecting the data.” This is done by applying the adjoint of the scattering operator to the data. This backprojected image is equivalent to that obtained by applying to the perturbed coefficient the composition of the scattering operator followed by its adjoint. We analyze this composite operator, and show that it is a paired Lagrangian operator. The properties of such operators explain the origin of certain artifacts in the backprojected image.

Aerial activity of linyphiid spiders: modelling dispersal distances from meteorology and behaviour

Summary Dispersal parameters are critical for modelling spatially dynamic populations yet remain among the most difficult to quantify. Linyphiid spider aerial dispersal by ‘ballooning’ on silk threads is dependent on meteorological factors and amenable to analysis and quantification. Spider aerial activity was measured during consecutive 10‐min periods for up to 11 h a day. Aerial density was measured at four heights using sticky traps. The time intervals between successive flights were measured by observing spiders landing and taking‐off. Meteorological measurements (wind speeds and temperatures) were taken simultaneously with the collection of airborne spiders, and used to calculate Richardson numbers to estimate atmospheric turbulence. Numbers of airborne spiders on any given day, and their vertical density profile on different days, were significantly correlated with Richardson numbers. Single flight distances were modelled using estimates of ascent and descent rates, the vertical density profile of airborne spiders and the wind speeds they experience aloft. The distributions of single flight distances and the time spent between successive flights were combined in an alternating renewal process to model the number of flights and the total daily dispersal distances of ballooning spiders as a function of available dispersal time. On a day with, for example, 6 h of suitable weather, linyphiid spiders can potentially disperse a mean distance of approximately 30 km downwind. Synthesis and applications. We have developed a dispersal model of linyphiid spiders that is central to the further development of spatially dynamic population models of these spiders in agricultural landscapes. It could also be adapted for application to other wind‐borne organisms. Such models have a key role in the future management of sustainable agricultural systems where natural predators are seen as major components of pest control.

Physical activity and resting metabolic rate.

The direct effects of physical activity interventions on energy expenditure are relatively small when placed in the context of total daily energy demands. Hence, the suggestion has been made that exercise produces energetic benefits in other components of the daily energy budget, thus generating a net effect on energy balance much greater than the direct energy cost of the exercise alone. Resting metabolic rate (RMR) is the largest component of the daily energy budget in most human societies and, therefore, any increases in RMR in response to exercise interventions are potentially of great importance. Animal studies have generally shown that single exercise events and longer-term training produce increases in RMR. This effect is observed in longer-term interventions despite parallel decreases in body mass and fat mass. Flight is an exception, as both single flights and long-term flight training induce reductions in RMR. Studies in animals that measure the effect of voluntary exercise regimens on RMR are less commonly performed and do not show the same response as that to forced exercise. In particular, they indicate that exercise does not induce elevations in RMR. Many studies of human subjects indicate a short-term elevation in RMR in response to single exercise events (generally termed the excess post-exercise O2 consumption; EPOC). This EPOC appears to have two phases, one lasting < 2 h and a smaller much more prolonged effect lasting up to 48 h. Many studies have shown that long-term training increases RMR, but many other studies have failed to find such effects. Data concerning long-term effects of training are potentially confounded by some studies not leaving sufficient time after the last exercise bout for the termination of the long-term EPOC. Long-term effects of training include increases in RMR due to increases in lean muscle mass. Extreme interventions, however, may induce reductions in RMR, in spite of the increased lean tissue mass, similar to the changes observed in animals in response to flight.

Short-duration space flight and hearing loss

The study goal was to determine whether a single Space Shuttle mission can induce decrements in astronaut hearing. Study design We retrospectively compared audiogram information obtained from Space Shuttle astronauts at 10 days preflight, day of return (R + 0), 3 days after landing return (R + 3), and at a mean delayed postflight follow-up of 8 months. Temporary threshold shift (mean, 4.6 dB) was noted in R + 0 versus preflight conditions (P < 0.01). Small permanent threshold shifts (mean, 0.83 dB) were found at R + 3 and postflight follow-up compared with preflight in the lower frequencies (500 to 2000 Hz), and corresponding pure tone average (P < 0.001). Conclusions and significance The data indicate that a single Shuttle flight can induce a substantial temporary threshold shift and a small but statistically significant permanent threshold shift, particularly in the frequencies involved in speech reception. Although single-mission effects are small, cumulative effects over several missions may ultimately produce clinically significant hearing loss.

Meridional distributions of aerosol particle number concentrations in the upper troposphere and lower stratosphere obtained by Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container (CARIBIC) flights

Number concentrations of submicrometer aerosol particles at altitudes of 8.5–11.3 km were measured along a single flight route between Germany (∼50°N, ∼10°E) and the Indic (∼5°N, ∼80°E) over 3 years using a commercial aircraft platform (project Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container (CARIBIC)). During 41 intercontinental flights (∼380 flight hours), more than one million individual particle concentration measurements were made, yielding a comprehensive and unique aerosol data set. Using these data, the first meridional and seasonal probability distributions for ultrafine particles and for Aitken mode plus accumulation mode particles in the upper troposphere (UT) and lower stratosphere (LS) were derived. High particle number concentrations were observed in summer at tropical latitudes over the Arabian Sea and at midlatitudes over Europe, in contrast to lower values in the subtropics over the Middle East. This distribution primarily reflects the vertical transport pattern of the atmosphere. In winter, number concentrations were generally lower. The Intertropical Convergence Zone (ITCZ) was identified as a region of pronounced particle formation, but particle nucleation also occurred in the upper troposphere at midlatitudes. At tropical latitudes, convective transport and photochemistry appear to be the main driving forces for particle formation in the free troposphere. Consistent with these observations, integral length scales calculated from the aerosol data ranged from 6 to 12 km. Compared to particle concentrations in the midlatitudinal upper troposphere, those in the lowermost stratosphere were lower in winter, but equal or higher in summer. This seasonality is likely caused by stronger in‐mixing of upper tropospheric air in summer.