Radar
Animal Migration
Saturn
Spacecraft
Extraterrestrial Environment
Topography of the lunar poles from radar interferometry: a survey of cold trap locations. (1/71)
Detailed topographic maps of the lunar poles have been obtained by Earth-based radar interferometry with the 3.5-centimeter wavelength Goldstone Solar System Radar. The interferometer provided maps 300 kilometers by 1000 kilometers of both polar regions at 150-meter spatial resolution and 50-meter height resolution. Using ray tracing, these digital elevation models were used to locate regions that are in permanent shadow from solar illumination and may harbor ice deposits. Estimates of the total extent of shadowed areas poleward of 87.5 degrees latitude are 1030 and 2550 square kilometers for the north and south poles, respectively. (+info)Harmonic oscillatory orientation relative to the wind in nocturnal roosting flights of the swift Apus apus. (2/71)
Swifts regularly spend the night flying at high altitude. From previous studies based on tracking radar observations, we know that they stay airborne during the night and prefer to orient themselves into the wind direction with an increased angular concentration with increasing wind speed. In this study, we investigated the orientation relative to the wind of individual swifts by frequency (discrete Fourier transform) and autocorrelation analysis based on time series (10s intervals) of the angle between the swifts' heading and the wind direction for radar trackings of long duration (9-60 min). The swifts often showed a significant harmonic oscillation of their heading direction relative to the wind, with a frequency mostly in the range 1-17 mHz, corresponding to cycle periods of 1-16 min. The swifts also sometimes performed circling flights at low wind speeds. Wind speed ranged from 1.3 to 14.8 m s(-1), and we expected to find different patterns of orientation at different wind speeds, assuming that the swifts adapt their orientation to avoid substantial displacement during their nocturnal flights. However, oscillatory orientation was found at all wind speeds with variable frequencies/periods that did not show any consistent relationship with wind speed. It remains to be shown whether cyclic heading changes are a regular feature of bird orientation. (+info)Instrumental methods for studies of structure and function of root systems of large trees. (3/71)
New methods using different physical principles have been successfully applied in studies of root systems of large trees. The ground-penetrating radar technique provides 3D images of coarse roots (starting with a diameter of about 20 mm) from the soil surface down to a depth of several metres. This can even be done under layers of undisturbed materials such as concrete, asphalt and water. Fine roots cannot be visualized by this method, but the total rooted volume of soil can be determined. The differential electric conductance method has been used for fast measurement of conducting (absorbing) root surfaces. However, more testing is needed. Both these methods are non-invasive. The results can be verified by an almost harmless excavation of whole root systems, including fine roots, using the ultrasonic air-stream (air-spade) method. This method is suitable for all studies, as well as practical operations on roots or objects in their vicinity, where a gentle approach is required. Sap flow measurements on their own or in tandem with soil moisture monitoring play a leading role in studying root function and hydraulic redistribution of flow in the soil. The water absorption function of roots can be studied by measuring sap flow on individual root branches directly (as on crown branches) and also indirectly, by measuring the radial pattern of sap flow in different sapwood depths at the base of a stem. Root zone architecture can also be estimated indirectly by studying its functionality. The heat field deformation method with multi-point sensors has been found to be very convenient for this purpose. A combination of several such methods is recommended whenever possible, in order to obtain detailed information about the root systems of trees. (+info)Radar evidence for liquid surfaces on Titan. (4/71)
Arecibo radar observations of Titan at 13-centimeter wavelength indicate that most of the echo power is in a diffusely scattered component but that a small specular component is present for about 75% of the subearth locations observed. These specular echoes have properties consistent with those expected for areas of liquid hydrocarbons. Knowledge of the areal extent and depth of any deposits of liquid hydrocarbons could strongly constrain the history of Titan's atmosphere and surface. (+info)Tracking butterfly flight paths across the landscape with harmonic radar. (5/71)
For the first time, the flight paths of five butterfly species were successfully tracked using harmonic radar within an agricultural landscape. Until now, butterfly mobility has been predominantly studied using visual observations and mark-recapture experiments. Attachment of a light-weight radar transponder to the butterfly's thorax did not significantly affect behaviour or mobility. Tracks were analysed for straightness, duration, displacement, ground speed, foraging and the influence of linear landscape features on flight direction. Two main styles of track were identified: (A) fast linear flight and (B) slower nonlinear flights involving a period of foraging and/or looped sections of flight. These loops potentially perform an orientation function, and were often associated with areas of forage. In the absence of forage, linear features did not provide a guiding effect on flight direction, and only dense treelines were perceived as barriers. The results provide tentative support for non-random dispersal and a perceptual range of 100-200 m for these species. This study has demonstrated a methodology of significant value for future investigation of butterfly mobility and dispersal. (+info)Cassini radar views the surface of Titan. (6/71)
The Cassini Titan Radar Mapper imaged about 1% of Titan's surface at a resolution of approximately 0.5 kilometer, and larger areas of the globe in lower resolution modes. The images reveal a complex surface, with areas of low relief and a variety of geologic features suggestive of dome-like volcanic constructs, flows, and sinuous channels. The surface appears to be young, with few impact craters. Scattering and dielectric properties are consistent with porous ice or organics. Dark patches in the radar images show high brightness temperatures and high emissivity and are consistent with frozen hydrocarbons. (+info)The sand seas of Titan: Cassini RADAR observations of longitudinal dunes. (7/71)
The most recent Cassini RADAR images of Titan show widespread regions (up to 1500 kilometers by 200 kilometers) of near-parallel radar-dark linear features that appear to be seas of longitudinal dunes similar to those seen in the Namib desert on Earth. The Ku-band (2.17-centimeter wavelength) images show approximately 100-meter ridges consistent with duneforms and reveal flow interactions with underlying hills. The distribution and orientation of the dunes support a model of fluctuating surface winds of approximately 0.5 meter per second resulting from the combination of an eastward flow with a variable tidal wind. The existence of dunes also requires geological processes that create sand-sized (100- to 300-micrometer) particulates and a lack of persistent equatorial surface liquids to act as sand traps. (+info)Energetic influence on gull flight strategy selection. (8/71)
During non-migratory flight, gulls (Larids) use a wide variety of flight strategies. We investigate the extent to which the energy balance of a bird explains flight strategy selection. We develop a model based on optimal foraging and aerodynamic theories, to calculate the ground speeds and airspeeds at which a gull is expected to flap or soar during foraging flight. The model results are compared with observed flight speeds, directions, and flight strategies of two species of gulls, the black-headed gull Larus ridibundus and the lesser black-backed gull Larus fuscus. The observations were made using a tracking radar over land in The Netherlands. The model suggests that, especially at combinations of low ground speed (approximately 5-10 m s(-1)), high air speed (approximately 20-25 m s(-1)) and low ground and air speed, gulls should favor soaring flight. At intermediate ground and air speeds the predicted net energy gain is similar for soaring and flapping. Hence the ratio of flapping to soaring may be higher than for other air and ground speed combinations. This range of speeds is broadest for black-headed gulls. The model results are supported by the observations. For example, flapping is more prevalent at speeds where the predicted net energy gain is similar for both strategies. Interestingly, combinations of air speed and flight speed that, according to the model, would result in a loss of net energy gain, were not observed. Additional factors that may influence flight strategy selection are also briefly discussed. (+info)I'm sorry for any confusion, but "Radar" is not a medical term. Radar is an acronym that stands for Radio Detection and Ranging, which is a technology used in detecting the range, angle, or velocity of objects using radio waves. It is commonly used in various fields such as aviation, navigation, meteorology, and defense. If you have any medical terms you would like me to define, please let me know!
In medical terms, "wind" is not a widely used or recognized term. It might be used informally to describe symptoms such as abdominal bloating, rumbling, or the sensation of gas moving within the intestines. However, these sensations are more accurately described as related to bowel function and gas in the digestive tract. If you're experiencing persistent or severe symptoms that you're describing as "wind," it would be best to consult with a healthcare professional for a proper evaluation.
Animal migration is a seasonal movement of animals from one place to another, typically over long distances, to find food, reproduce, or escape harsh conditions. This phenomenon is observed in various species, including birds, mammals, fish, and insects. The routes and destinations of these migrations are often genetically programmed and can be quite complex. Animal migration has important ecological consequences and is influenced by factors such as climate change, habitat loss, and human activities.
I'm sorry for any confusion, but the term "Saturn" is not a medical term. In general, it refers to the sixth planet from the sun in our solar system. If you have any medical concerns or questions, I would be happy to try and help answer those for you.
I'm sorry for any confusion, but "spacecraft" is not a term typically used in medical definitions. A spacecraft is a vehicle or machine designed to fly in outer space. It may be used to transport humans or cargo to and from space stations, conduct scientific research, or explore other celestial bodies such as the moon, planets, and asteroids. If you have any questions related to medical terminology, I'd be happy to help!
"Animal Flight" is not a medical term per se, but it is a concept that is studied in the field of comparative physiology and biomechanics, which are disciplines related to medicine. Animal flight refers to the ability of certain animal species to move through the air by flapping their wings or other appendages. This mode of locomotion is most commonly associated with birds, bats, and insects, but some mammals such as flying squirrels and sugar gliders are also capable of gliding through the air.
The study of animal flight involves understanding the biomechanics of how animals generate lift and propulsion, as well as the physiological adaptations that allow them to sustain flight. For example, birds have lightweight skeletons and powerful chest muscles that enable them to flap their wings rapidly and generate lift. Bats, on the other hand, use a more complex system of membranes and joints to manipulate their wings and achieve maneuverability in flight.
Understanding animal flight has important implications for the design of aircraft and other engineering systems, as well as for our broader understanding of how animals have evolved to adapt to their environments.
The term "extraterrestrial environment" is not typically used in a medical context, but rather in the fields of astronomy and astrobiology. It generally refers to any physical environment outside of Earth, including the surfaces and atmospheres of other planets, moons, asteroids, comets, and interstellar space.
In a broader sense, one might use the term "extraterrestrial environment" to refer to any physical conditions that are not found naturally on Earth, such as extreme temperatures, radiation levels, or atmospheric compositions. However, this is not a standard medical definition.
It's worth noting that there may be potential health implications for humans who travel to extraterrestrial environments, as they would be exposed to new and potentially hazardous conditions. As such, space medicine is a growing field of research that aims to understand and mitigate the health risks associated with space travel.
"Ice" is a slang term that is commonly used to refer to crystal methamphetamine, which is a powerful and highly addictive stimulant drug. It gets its name from its crystalline appearance. Medically, methamphetamine is used in the treatment of attention deficit hyperactivity disorder (ADHD) and obesity, but only under strict medical supervision due to its potential for abuse and serious side effects.
Crystal methamphetamine, on the other hand, is an illegal drug that is produced and sold on the black market. It can be smoked, injected, snorted or swallowed, and it produces a euphoric rush followed by a long-lasting high. Long-term use of crystal methamphetamine can lead to serious health consequences, including addiction, psychosis, dental problems (meth mouth), memory loss, aggression, and cardiovascular damage.