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At least 235 records · Page 13Linked to original sources
PubMed1996

Galileo Doppler Measurements of the Deep Zonal Winds at Jupiter

Changes in the speed of the Galileo probe caused by zonal winds created a small but measurable Doppler effect in the probe relay carrier frequency. Analysis of the probe relay link frequency allows direct measurements of the speed of Jupiter's zonal winds beneath the cloud tops. The deep winds were prograde and strong, reaching a sustained 190 to 200 meters per second at an altitude marked by a pressure of 24 bars. The depth and strength of the zonal winds severely constrain dynamic modeling of the deeper layers and begin to rule out many shallow weather theories.

Journal Article↗
PubMed1997

Earth-Based Radio Tracking of the Galileo Probe for Jupiter Wind Estimation

Although the Galileo probe was designed to communicate only to the orbiter, the probe radio signal was detected at two Earth-based radio observatories where the signal was a billion times weaker. The measured signal frequency was used to derive a vertical profile of the jovian zonal wind speed. Due to the mission geometry, the Earth-based wind estimates are less sensitive to descent trajectory errors than estimates based on probe-orbiter Doppler measurements. The two estimates of wind profiles agree qualitatively; both show high wind speeds at all depths sampled.

Journal Article↗
PubMed1995

Physiological properties of wind-sensitive and tactile trichoid sensilla on the ovipositor and their role during oviposition in the locust

The physiological properties of the ovipositor hair sensilla of the desert locust and their responses to wind and to direct mechanical displacement are described. The hairs on the external surfaces of the ventral and dorsal ovipositor valves respond to wind stimulation, whereas the hairs on the inner surfaces of the dorsal valves are not wind-sensitive. All ovipositor hairs, however, respond to tactile displacement. Imposed tactile stimulation reveals two physiologically distinct types of ovipositor tactile hairs: the hairs on the inner surface of the dorsal valves are high-threshold hairs (threshold angular deflection of 26­67 ° at 1 Hz) that respond phasically, whereas the hairs on the lateral and ventral areas of the ventral valves and the lateral areas of the dorsal valves are low-threshold hairs (threshold angular deflection of 6­20 ° at 1 Hz) that respond phasotonically. There is no apparent difference in the length of the two physiologically distinct types of hairs. Both high- and low-threshold hairs are directionally sensitive, with maximal responses to proximal deflection, towards the abdomen, and are also velocity-sensitive. High-threshold hairs have velocity thresholds of 40­50 ° s-1 for some hairs and 110­140 ° s-1 for others for a deflection angle of 35 °, whereas low-threshold hairs have lower velocity thresholds of less than 5 ° s-1 for the same deflection. High-threshold hairs adapt rapidly to repetitive stimulation after as few as four cycles of stimulation at 0.5 Hz. Low-threshold hairs continue to respond after 40 cycles of stimulation at 0.5 Hz and show little adaptation to repetitive stimulation at frequencies ranging from 0.1 to 5 Hz. Low-threshold hairs respond with bursts of spikes at frequencies that reflect both the velocity and the duration of the stimulus. Furthermore, low-threshold hairs show little adaptation after 30 min of stimulation that simulates oviposition digging. It is suggested (a) that low- and high-threshold ovipositor hairs detect phasic wind and/or tactile stimuli in non-ovipositing locusts and (b) that low-threshold hairs can also signal rhythmic tactile inputs during oviposition digging.

Journal Article↗
PubMed1997

A new low-turbulence wind tunnel for bird flight experiments at Lund University, Sweden

A new wind tunnel for experiments on bird flight was completed at Lund University, Sweden, in September 1994. It is a closed-circuit design, with a settling section containing five screens and a contraction ratio of 12.25. The test section is octagonal, 1.20 m wide by 1.08 m high. The first 1.2 m of its length is enclosed by acrylic walls, and the last 0.5 m is open, giving unrestricted access. Experiments can be carried out in both the open and closed parts, and comparison between them can potentially be used to measure the lift effect correction. The fan is driven by an a.c. motor with a variable-frequency power supply, allowing the wind speed to be varied continuously from 0 to 38 m s-1. The whole machine can be tilted to give up to 8 ° descent and 6 ° climb. A pitot-static survey in the test section showed that the air speed was within ±1.3 % of the mean at 116 out of 119 sample points, exceeding this deviation at only three points at the edges. A hot-wire anemometer survey showed that the turbulence level in the closed part of the test section was below 0.04 % of the wind speed throughout most of the closed part of the test section, rising to approximately 0.06 % in the middle of the open part. No residual rotation from the fan could be detected in the test section. No decrease in wind speed was detectable beyond 3 cm from the side walls of the closed part, and turbulence was minimal beyond 10 cm from the walls. The installation of a safety net at the entrance to the test section increased the turbulence level by a factor of at least 30, to 1.2 % longitudinally and 1.0 % transversely.

Journal Article↗
PubMed2002

Wingbeat frequency of barn swallows and house martins: a comparison between free flight and wind tunnel experiments.

The flight paths and wingbeat patterns of 39 barn swallows (Hirundo rustica) and 26 house martins (Delichon urbica) were recorded by tracking radar during the spring migration. Depending mostly on flight angle, hirundines performed anything from continuous flapping flight during climbing to single pulse-like wing beats during descent. Unlike most other passerines, hirundines rarely showed regular flapping and rest phases, allowing them to be distinguished from other bird migrants by radar echo signatures. Effective wingbeat frequency (F(eff)) was calculated as the mean number of wing beats per second, including non-flapping phases. Under comparable flight conditions, F(eff) was higher in house martins than in barn swallows. Within species, F(eff) values were higher during climbing and slow flying than during descent. Of the variance in F(eff), 71% could be explained by climb rate, air speed and species; similar results were obtained in the wind tunnel. Under comparable flight conditions, barn swallows and house martins in free flight had significantly lower values of F(eff) than individuals in wind tunnel experiments (by 40% and 32%, respectively). This difference may at least partly be due to the shorter wings of the juveniles tested in the wind tunnel during autumn. However, it seems unlikely that this can account for all of the large difference. It is suggested that wind tunnel experiments might overestimate birds' flight costs compared with free flight.

Animals↗
PubMed2005

Enhanced wind-up of the C-fiber-mediated nociceptive flexor reflex movement following painful diabetic neuropathy in mice.

We examined wind-up of the nociceptive flexor withdrawal responses in diabetic mice that had developed tactile allodynia after treatment with streptozotocin (STZ). In control and STZ-treated mice, simultaneous activation of Adelta- and C-fibers by electrical stimuli at C-fiber intensity delivered to the ventral aspect of the toe elicited a biphasic withdrawal reflex composed of short- and long-latency movements of the ipsilateral hind paw that were respectively mediated by activation of Adelta- and C-fibers. There were no significant differences between control and diabetic mice in the activation threshold of each reflex movement or the amplitude of reflexes elicited by various stimulus intensities. However, a repetitive conditioning stimulus (CS) elicited significantly greater wind-up of the C-fiber-mediated movement and early saturation of wind-up in diabetic mice. In both control and diabetic mice, the CS elicited no or occasionally slight wind-up of the A delta-fiber-mediated movement. Moreover, post-CS facilitation, which reflects the prolonged excitability increase, was observed in both Adelta-fiber- and C-fiber-mediated movements of control mice, whereas significant post-CS facilitation was only obtained in the C-fiber-mediated movement of diabetic mice, which may reflect supraspinal descending influences. Such changes in the excitability of spinal neurons in diabetic mice may represent some aspect of painful diabetic neuropathy.

Animals↗
PubMed2004

Wind-flow measurement over the Subaru Telescope.

Wind flows over the 8.2-m Subaru Telescope at Mauna Kea in Hawaii were analyzed with a correlation method. Three or four wind flows were detected from our measurements. Spatial and temporal resolution of the wind-flow analysis across the 8.2 m pupil were investigated experimentally. A three-dimensional spatiotemporal-frequency analysis was also applied to the wind-flow data.

Journal Article↗
PubMed2005

First retrieval of vertical profiles of turbulence characteristics and horizontal wind velocity from solar transmission measurements at 212 and 405 GHz.

We report on the investigation and successful application of vertical profiling of the structure parameter C2m and of the outer scale L0 of absorption fluctuations and of the horizontal wind velocity (vector) during daytime by the analysis of solar transmission measurements. The method is relatively simple and straightforward so that the presented (or a similar) technique could be used in the routine remote sensing of daytime C2m, L0, and wind profiles. It requires multiple beams pointing in different directions at the Sun. The retrieved profiles are consistent with the current knowledge of atmospheric physics. Simultaneous in situ wind velocity measurements agree with the retrieved wind velocity in the lowest 100 m above ground within the measurement uncertainties of less than +/-2 m/s. The derived values of C2m at 200 m above ground are in good agreement (within a factor of 1.5) with the findings of an earlier investigation at the same test site. Finally, it is shown that irradiance fluctuations of millimeter and submillimeter waves are dominantly affected by humidity fluctuations, even at a dry and elevated site.

Journal Article↗
PubMed1990

[Myofunction in players of wind instruments].

Within the framework of a longitudinal study, tongue function was examined for maximum pressure, force/time ratio and motility with the aid of a force, pressure and impulse transducer in 181 pupils playing wind instruments and 120 control persons. The methods designed for this purpose provided a reproduction of tongue performance during the act of blowing a wind instrument. The results of this study show statistically significant differences between persons who play wind instruments and those who do not and players of other types of instruments. The data derived from these results permit statements about the degree of muscular malfunction among players of wind instruments. Furthermore, they are helpful in the assessment of therapeutic success or failure.

Facial Muscles↗
PubMed1989

[A case report of ventricular septal defect accompanied by winded and elongated malformation of the aortic arch].

A three-year-old boy, surgically treated for a ventricular septal defect, had a winded and elongated aortic arch between the left common carotid artery and the left subclavian artery. Angiography revealed that the arch was positioned more caudalward than normally, and that it was in contact with the left pulmonary artery at a point near the central portion of the arch (i.e., near the position of the ductus arteriosus). The embryological cause of this malformation was speculated. It seemed unlikely that malformations was caused by involution, abnormal growth, etc., of the components of the great vessels in the coursed of embryonic development, but rather to have been caused by an abnormal elongation of the artery at the fourth arch and of the ventral artery between the 6th and 7th intersegmental artery, which had occurred after normal embryonic development. Under extracorporeal circulation, where blood was returned to the patient via the femoral artery, the patient underwent open heart surgery to close the ventricular septal defect. Pressure monitoring during the operation revealed no pressure loss in the winded and elongated portion of the artery; hence, the malformation seemed to cause no hemodynamic problems at present. Considering that the patient is only three years old and that the aorta will continue to grow, we have decided to refrain from any surgical treatment of the winded and alongated part of the aorta for the time being. However, the patient might develop aortic aneurysm in the future because of the relative coactation of the aorta and the insufficient mechanical strength of the winded and elongated area.(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta, Thoracic↗
PubMed1989

Wind-chill equations predicting whole-body heat loss for a range of typical civilian outdoor clothing ensembles.

A thermal manikin with constant skin temperature and a wind-chill tunnel with constant air temperatures and wind speeds were used to measure whole-body heat loss for seven ensembles chosen to represent the full range of civilian outdoor clothing in use for everyday, nonsporting wear. Equations fitting the data with correlation coefficients exceeding 0.99 were derived for each ensemble, and diagrams were produced with these equations to interpolate and extend the range of conditions. The conditions studied were those resulting in total heat loss from 50 to 250 W.m-2, so very little extrapolation was required. The wind-chill equivalent temperature (with reference to 2 m.s-1), based on the average value for all seven ensembles, showed good agreement on this measure. The values predicted on the basis of whole-body heat loss through clothing were shown to be much lower than those predicted from the Siple wind-chill index for unprotected skin.

Air Movements↗
PubMed1996

The role of N-methyl-D-aspartate (NMDA) receptors in wind-up: a mathematical model.

We present a mathematical model for the phenomenon of wind-up (Mendell, 1966, Exper. Neur. 16,316-22) which occurs in many neurons. We concentrate on its occurrence in the substantia gelatinosa of the dorsal horns of the spinal cord, where it is connected with certain pathological and nonpathological pain states. The model is a development of the model by Britton & Skevington (1989, J. Theor. Biol. 137, 91-105) for Melzack & Wall's gate control theory of pain (1965, Science, New York, 150, 971-9; 1982, The Challenge of Pain, Penguin: Harmondsworth), modified to take account of more recent information. Its variables are the electric potentials of various cells in the midbrain and the spinal cord. Britton & Skevington's original model simulated many of the phenomena observed in acute pain in humans, but not the wind-up mechanism. This is not surprising, since this model did not include the N-methyl-D-aspartate (NMDA) receptors that are now recognized as being crucial to the phenomenon. Here we rectify this omission, and obtain good agreement between the model and experimental data on wind-up. The positive feedback that NMDA receptors exhibit is shown to be the essential feature in producing wind-up. As an independent test of the model we simulate a completely different experimental set-up, and obtain good qualitative agreement with data there. Finally, we present a prediction of the model that has yet to be tested experimentally.

Animals↗
PubMed1998

Breathing difficulties in wind instrument players.

Performance of a wind instrument requires appreciable lung volume and diaphragmatic mechanical force, skilled breath control, adequate patency and humidity of air passages, and precise coordination of the oropharyngeal cavity. Depending on the instrument class, variable rates of air flow, pressure, and duration are necessary to produce optimal tone quality. Wind players may be seriously impaired by respiratory diseases that, comparatively, might appear trivial to the nonperformer. The workplace environment should be assessed for occupational hazards when managing these patients, and smoking should be particularly discouraged. Controversy exists implicating wind instrument use in the exacerbation of respiratory disease, including bronchial, laryngeal, pharyngeal, and oral anatomic changes--a result of the constant barotrauma of performance. Asthma is the most common chronic pulmonary disorder among wind players, and therapeutic programs that include breath training and physical exercise improve symptoms, endurance, and general well-being.

Air Pressure↗
PubMed2004

Correction of clothing insulation for movement and wind effects, a meta-analysis.

A meta-analysis of the effect of body and air movement on the insulation provided by workwear and cold-weather clothing [1.22 clo (0.189 m2 degrees C W(-1)) < I(T)<4.14 clo (0.642 m2 degrees C W(-1))] using data from different sources was performed. For the effect of walking, datasets could be merged and a single prediction equation produced (r2=0.91). For the effect of wind, and interaction of movement and wind, separate equations were required for regular workwear (r2 = 0.93) and cold-weather clothing (r2 = 0.97). Differences were mainly due to the different amounts of nude surface area. An interaction between wind and walking effects was present (the size of the combined effects is less than the sum of the separate effects), and for cold-weather clothing an effect of clothing air permeability (p) was present (high p --> bigger effect). The resulting prediction equations will be proposed for inclusion in European and ISO standards on protective clothing to assist the user in determining the real-life clothing insulation value.

Humans↗
PubMed2002

Seed dispersal by wind, birds, and bats between Philippine montane rainforest and successional vegetation.

In the moist Neotropics, vertebrate frugivores have a much greater role in the dispersal of forest and successional woody plants than wind, and bats rather than birds play the dominant role in dispersing early successional species. I investigated whether these patterns also occurred in a Philippine montane rainforest and adjacent successional vegetation. I also asked whether seed mass was related to probability of dispersal between habitats. A greater number of woody species and stems in the forest produced vertebrate-dispersed seeds than wind-dispersed seeds. Although input of forest seeds into the successional area was dominated by vertebrate-dispersed seeds in terms of species richness, wind-dispersed seeds landed in densities 15 times higher. Frugivorous birds dispersed more forest seeds and species into the successional area than bats, and more successional seeds and species into the forest. As expected, seed input declined with distance from source habitat. Low input of forest seeds into the successional area at the farthest distance sampled, 40 m from forest edge, particularly for vertebrate-dispersed seeds, suggests very limited dispersal out of forest even into a habitat in which woody successional vegetation provides perches and fruit resources. For species of vertebrate-dispersed successional seeds, probability of dispersal into forest declined significantly with seed mass.

Altitude↗
PubMed1999

Aerobiology of Artemisia airborne pollen in Murcia (SE Spain) and its relationship with weather variables: annual and intradiurnal variations for three different species. Wind vectors as a tool in determining pollen origin.

Detailed results from a 2-year survey of airborne pollen concentrations of Artemisia in Murcia are presented. Three consecutive pollen seasons of Artemisia occurring each year, related to three different species (A. campestris, A. herba-alba and A. barrelieri), were observed. A winter blooming of Artemisia could explain the incidence of subsequent pollinosis in the Murcia area. With regard to meteorological parameters, mathematical analyses showed relationships between daily pollen concentrations of Artemisia in summer-autumn and precipitations that occurred 6-8 weeks before. The cumulative percentage of insolation from 1 March seemed to be related to blooming onsets. Once pollination has begun, meteorological factors do not seem to influence pollen concentrations significantly. Intradiurnal patterns of pollen concentrations were similar for late summer and winter species (A. campestris and A. barrelieri). During autumn blooming (A. herba-alba), the intradiurnal pattern was particularly erratic. Theoretical values of wind run were obtained for each pollen season by the graphical sum of hourly wind vectors. When theoretical wind run was mapped onto the vegetation pattern, supposed pollen source locations were obtained for each hour. By comparing supposed hourly pollen origins with the intradiurnal patterns of pollen concentrations, it can be seen that this simple model explains variations in mean pollen concentrations throughout the day.

Allergens↗
PubMed1992

Wind-induced accidents of road vehicles.

This paper describes the results of a project that collected and collated data for wind-induced vehicle accidents that occurred in the United Kingdom during the major storm of 25 January 1990. The results of this data analysis are used to determine which vehicles are most at risk during windy periods, the nature of the accidents that were caused, and the likely values of accident wind speeds. Also the adequacy of a computer program that can predict such wind speeds (the program BLOWOVER) is assessed as far as the available data allows.

Accidents, Traffic↗
PubMed1994

Impaired cardiovascular responsiveness to an acute cold wind stress in streptozotocin-diabetic rats.

In vivo cardiovascular responses were measured using modified impedance cardiographic techniques in urethane-anesthetized (1.5 g/kg) streptozotocin-diabetic (STZ; 65 mg/kg) rats during acute (30 min) cold wind (0 degree C, 1 m/s) exposure. Both control (CON) and diabetic (STZ) groups experienced significant decreases (P < 0.05) in colonic temperature (Tcol) over time with the STZ rats exhibiting greater decrements (P < 0.05) throughout the later stages of cooling. Similar increases (P < 0.05) in cardiac output (Q) and mean arterial pressure (MAP) were observed in both groups during the initial 10 min of cold exposure. Heart rate (HR) accounted for the major portion of the rise in Q since stroke volume remained relatively constant throughout the experimental period. During the later stages of cold wind exposure, Q and MAP were significantly lower (P < 0.05) in STZ compared to CON. In fact, Q and MAP continued to rise during the entire cold period in CON whereas the STZ group failed to respond to the continued decline in Tcol. The results indicate that STZ rats are more vulnerable to cold wind stress as evidenced by the impaired responsiveness of the cardiovascular system to hypothermia. The pattern of responses for both the thermoregulatory and cardiovascular systems could be partially explained by beta-receptor insensitivity to catecholamine stimulation.

Acute Disease↗