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PubMed1970

Temperature and transpiration resistances of xanthium leaves as affected by air temperature, humidity, and wind speed.

Transpiration and temperatures of single, attached leaves of Xanthium strumarium L. were measured in high intensity white light (1.2 calories per square centimeter per minute on a surface normal to the radiation), with abundant water supply, at wind speeds of 90, 225, and 450 centimeters per second, and during exposure to moist and dry air. Partitioning of absorbed radiation between transpiration and convection was determined, and transpiration resistances were computed.Leaf resistances decreased with increasing temperature (down to a minimum of 0.36 seconds per centimeter). Silicone rubber replicas of leaf surfaces proved that the decrease was due to increased stomatal apertures. At constant air temperature, leaf resistances were higher in dry than in moist air with the result that transpiration varied less than would have been predicted on the basis of the water-vapor pressure difference between leaf and air.The dependence of stomatal conductance on temperature and moisture content of the air caused the following effects. At air temperatures below 35 C, average leaf temperatures were above air temperature by an amount dependent on wind velocity; increasing wind diminished transpiration. At air temperatures above 35 C, leaf temperatures were below air temperatures, and increasing wind markedly increased transpiration. Leaf temperatures equaled air temperature near 35 C at all wind speeds and in moist as well as in dry air.

Journal Article↗

PubMed2001

Acoustic sounding of wind velocity profiles in a stratified moving atmosphere.

The paper deals with analytical and numerical studies of the effects of atmospheric stratification on acoustic remote sensing of wind velocity profiles by sodars. Both bistatic and monostatic schemes are considered. Formulas for the Doppler shift of an acoustic echo signal scattered by atmospheric turbulence advected with the mean wind in a stratified moving atmosphere are derived. Numerical studies of these formulas show that errors in retrieving wind velocity can be of the order of 1 m/s if atmospheric stratification is ignored. Formulas for the height at which wind velocity is retrieved are also derived. Approaches are proposed which allow one to take into account the effects of atmospheric stratification when restoring the wind velocity profile from measured values of the Doppler shift and the time interval of acoustic impulse propagation from a sodar to the scattering volume and back to the ground.

Journal Article↗

PubMed2000

The solar wind-magnetosphere-ionosphere system

The solar wind, magnetosphere, and ionosphere form a single system driven by the transfer of energy and momentum from the solar wind to the magnetosphere and ionosphere. Variations in the solar wind can lead to disruptions of space- and ground-based systems caused by enhanced currents flowing into the ionosphere and increased radiation in the near-Earth environment. The coupling between the solar wind and the magnetosphere is mediated and controlled by the magnetic field in the solar wind through the process of magnetic reconnection. Understanding of the global behavior of this system has improved markedly in the recent past from coordinated observations with a constellation of satellite and ground instruments.

Journal Article↗

PubMed2000

Effect of wind and solar radiation on metabolic heat production in a small desert rodent, Spermophilus tereticaudus.

To understand better how complex interactions between environmental variables affect the energy balance of small diurnal animals, we studied the effects of the absence and presence of 950 W m(-)(2) simulated solar radiation combined with wind speeds ranging from 0. 25 to 1.00 m s(-)(1) on the metabolic rate and body temperature of the round-tailed ground squirrel Spermophilus tereticaudus. As wind speed increased from 0.25 to 1.00 m s(-)(1), metabolic heat production increased by 0.94 W in the absence of solar radiation and by 0.98 W in the presence of 950 W m(-)(2) simulated solar radiation. Exposure to simulated solar radiation reduced metabolic heat production by 0.68 W at a wind speed of 0.25 m s(-)(1), by 0.64 W at 0.50 m s(-)(1) and by 0.64 W at 1.00 m s(-)(1). Body temperature was significantly affected by environmental conditions, ranging from 32. 5 degrees C at a wind speed of 1.0 m s(-)(1) and no irradiance to 35. 6 degrees C at a wind speed of 0.50 m s(-)(1) with 950 W m(-)(2 )short-wave irradiance. In addition, several unusual findings resulted from this study. The coat of S. tereticaudus is very sparse, and the observed heat transfer of 5.68+/-0.37 W m(-)(2 ) degrees C(-)(1) (mean +/- s.e.m., N=11) is much higher than expected from either allometric equations or comparative studies with other rodents of similar mass. Solar heat gain was remarkably low, equalling only 10 % of intercepted radiation and suggesting a remarkably high regional thermal resistance at the tissue level. Animals remained normally active and alert at body temperatures as low as 32.5 degrees C. These findings suggest a unique combination of adaptations that allow S. tereticaudus to exploit a harsh desert environment.

Animals↗

PubMed2004

Model of image degradation due to wind buffeting on an extremely large telescope.

A parametric model of wind buffeting on an extremely large telescope with a multipod secondary support is described. The model estimates wave-front errors that are due to wind buffeting on a segmented primary, wind-induced secondary figure and position errors, and primary-mirror deformations caused by wind forces on the secondary support. The approach is based on a Zernike expansion of pressure fluctuations, with simple models of stiffness, resonance, and control. The model shows that wind buffeting on a multipod attached to the primary mirror cell significantly degrades the image quality in a large telescope with a slow primary.

Journal Article↗

PubMed2006

Wind loads on ground-based telescopes.

One of the factors that can influence the performance of large optical telescopes is the vibration of the telescope structure due to unsteady wind inside the telescope enclosure. Estimating the resulting degradation in image quality has been difficult because of the relatively poor understanding of the flow characteristics. Significant progress has recently been made, informed by measurements in existing observatories, wind-tunnel tests, and computational fluid dynamic analyses. We combine the information from these sources to summarize the relevant wind characteristics and enable a model of the dynamic wind loads on a telescope structure within an enclosure. The amplitude, temporal spectrum, and spatial distribution of wind disturbances are defined as a function of relevant design parameters, providing a significant improvement in our understanding of an important design issue.

Journal Article↗

PubMed1976

Relation of musical wind instruments to malocclusion.

Eighty-four seventh graders of both sexes, not undergoing orthodontic treatment, participated in a double-blind study to determine the effect on the anterior teeth of playing a musical wind instrument. The instrument players were just beginning their studies. Seventh graders not playing a musical wind instrument served as the control group. Impressions and plaster casts were made of each mouth at the beginning and conclusion of the study. The plaster casts were marked with the same numerical code assigned to each student. Overjet and overbite measurements of the anterior teeth were taken from the plaster casts and recorded. Findings indicate that, on an individual basis, the effect on the anterior teeth of playing a musical wind instrument is unpredictable. Only on a group basis can a class of musical wind instruments be theorized to have a certain effect on the anterior teeth. The playing of a musical wind instrument should not be used as a substitute for orthodontic treatment.

Adolescent↗

PubMed1992

Inhibition of T4 DNA ligase activity by (+)-CC-1065: demonstration of the importance of the stiffening and winding effects of (+)-CC-1065 on DNA.

Non-denaturing gel electrophoresis analysis demonstrates that the stiffening and winding effects of (+)-CC-1065 produce unusual proximal and distal inhibition of T4 DNA ligase-catalysed ligation of covalently modified DNA. (+)-CC-1065 is a potent antitumor antibiotic produced by Streptomyces zelensis. This drug selectively bonds through N3 of adenine in DNA and lies in the minor groove of DNA, reacting in a highly sequence-selective manner. Previous studies (Lee et al., 1991) have shown that (+)-CC-1065 produces bending and winding of DNA. The DNA bending and sequence specificity is mediated by the alkylating 'A' subunit of (+)-CC-1065, while the close van der Waals contacts between the non-alkylating B and C subunits of (+)-CC-1065 and the floor of the minor groove of DNA are responsible for the winding of DNA. Covalent modification of oligomers with (+)-CC-1065 and structurally related drugs leads to preferential inhibition of T4 DNA ligase on the non-covalently modified strand to the 5' side of the covalent adduct site, but enhanced ligation of the covalently modified strand. We speculate that the differential effect on proximal strand ligation is due to a drug-induced winding and helix-stabilizing effect which occurs predominantly to the 5' side of the adduct. In addition to the proximal inhibition of ligation, we also describe a distal inhibition of T4 DNA ligase activity which occurs exclusively with drug-modified oligomers and that, if successful, would result in 180 degrees out-of-phase bent DNA following ligation. In this case, two 25 mers or a 21 plus a 29 mer are inhibited from ligation when modified with (+)-CC-1065. This distal ligation is unique to (+)-CC-1065 and its analogs that cause stiffening of the DNA helix. The (+)-CC-1065-induced stiffening effect was demonstrated using a circularization assay and was found to be associated with the close van der Waals contacts between the inside edge of (+)-CC-1065 and the floor of the minor groove, and also to the benzofuran moiety of (+)-ABC" (Adozelesin), a (+)-CC-1065 analog. We conclude from these studies that the DNA-winding and helix-stabilizing effects of these drug molecules can dramatically affect the efficiency of proximal ligation mediated by T4 DNA ligase, and the unusual helix-stiffening effect of (+)-CC-1065, (+)-AB'C' and (+)-ABC" can stabilize the structure of bent DNA formed by drug modification, which results in distal ligase inhibition.

Antibiotics, Antineoplastic↗

PubMed1980

The effect of a "wind-up" on forearm rotational velocity.

Subjects performed supination and pronation of the forearm against an inertial load with maximal voluntary effort, from either rest or when arresting the opposite motion of the load (a wind-up). The angular velocities produced at the mid-range of forearm movement were significantly greater with wind-up than without. The angle from which the movement began was significantly increased by wind-up. Isometric contractions produced torques which varied a great deal through the range of motion. While it was not possible to identify the physiology effects of wind-up, consideration was given to techniques which would achieve this aim. Wind-up was discussed in the context of skilled activity where sustained maximal contractions are unlikely throughout the activity.

Biomechanical Phenomena↗

PubMed1991

Wind and orientation of migrating birds: a review.

Migratory flights are strongly affected by wind, and birds have developed many adaptations to cope with wind effects. By day, overland migrants at high altitudes may often allow crosswinds to drift their tracks laterally from the preferred heading. In contrast, many birds at low altitude adjust their headings to compensate for drift, and may overcompensate to allow for previous drift. The relative motion of landscape features is probably used to sense drift, at least by day. By night, some overland migrants compensate fully for drift, but others do not. Compensation may be more common where there are prominent topographic features. Over the sea, compensation is rarely if ever total; wave patterns may allow partial compensation. Other adaptations can include reduction of drift by flying at times and/or altitudes without strong crosswinds. Some birds recognize the need to change course to allow for previous wind displacement, and reorient at least roughly toward the original route or destination. Some juveniles en route to previously unvisited wintering grounds seem to have this ability, but corroboration is needed. Such reorientation may not require a true navigation ability. However, some birds have unexplained abilities to sense the wind while aloft.

Altitude↗

PubMed1991

White noise analysis of graded response in a wind-sensitive, nonspiking interneuron of the cockroach.

1. A novel approach using a Gaussian white noise as stimulus is described which allowed quantitative analysis of neuronal responses in the cercal system of the cockroach, Periplaneta americana. Cerci were stimulated by air displacement which was modulated by a sinusoidal and a white noise signal. During the stimulation, intracellular recordings were made from a uniquely identifiable, nonspiking, local interneuron which locates within the terminal abdominal ganglion. The white noise stimulation was cross-correlated with the evoked response to compute first- and second-order kernels that could define the cell's response dynamics. 2. The interneuron, cell 101, has an exceptionally large transverse neurite that connects two asymmetrical dendritic arborizations located on both sides of the ganglion. 3. The first-order Wiener kernels in cell 101 were biphasic (differentiating). The waveforms of the kernels produced by the ipsilateral and contralateral stimulations were roughly mirror images of each other: the kernels produced by wind stimuli on the side ipsilateral to the cell body of the interneuron are initially depolarized and then hyperpolarized, whereas those on the other side are initially hyperpolarized. The polarity reversal occurred along the midline of the animal's body, and no well-defined kernel was produced by a stimulus directed head on or from the tail. 4. Mean square error (MSE) between the actual response and the model prediction suggests that the linear component in cell 101 comprises half of the cell's total response (MSEs for the linear models were about 50% at preferred directions), whereas the second-order, non-linear component is insignificant. The linear component of the wind-evoked response was bandpass with the preferred frequency of 70-90 Hz. 5. Accounting for a noise, we reasonably assumed that at high frequencies the graded response in cell 101 is linearly related to a modulation of the air displacement and sensitive to the rate of change of the signal (i.e., wind velocity) and the direction of its source. It is suggested that the dynamics of the first-order kernel simply reflect the dynamics of sensory receptors that respond linearly to wind stimulation.

Acoustic Stimulation↗

PubMed1996

Neural circuitry underlying linear representation of wind information in a nonspiking local interneuron of the cockroach.

In the cercal system of the cockroach Periplaneta americana, primary sensory interneurons exhibiting a sharp directional sensitivity respond to wind in a linear manner whereas those exhibiting an omnidirectional sensitivity respond nonlinearly. For example, the wind-evoked response in an identifiable, nonspiking local interneuron, 101, which responds preferentially to wind from the left versus the right, is characterized exclusively by a differential first-order (linear) kernel. However, the slow potential response in a cercal giant interneuron, GI-1, is omnidirectional, and characterized by a second-order (nonlinear) kernel with an elongated depolarizing peak on the diagonal with two off-diagonal valleys. We here examined the neural circuitry underlying the linear and nonlinear representations of wind information by the deprivation of inputs from particular sets of cercal hair afferents. Electrical stimulation of the ipsilateral (related to the soma) cercal nerve elicited a depolarizing potential in 101, which was followed by delayed hyperpolarization. A continuous flow of 10(-4) M picrotoxin, which selectively blocked this delayed hyperpolarization, resulted in a significant change in the 101 response from linear to nonlinear. Because no frequency-doubling response was observed, the nonlinearity is due to signal compression (or rectification) that reflects the mechanical property of cercal afferents. This is consistent with the hypothesis that the linear representation in 101 is based on a subtraction process between two subsets of particular column hairs, whose best optimal directions are opposite to each other.

Animals↗

PubMed1993

Excitatory influence of wind-sensitive local interneurons on an ascending interneuron in the cricket cercal sensory system.

This study examined the effects of a set of identified wind-sensitive local interneurons (9DL interneurons) on the wind-evoked spike output and directional sensitivity of an ascending interneuron (10-3) in the cricket (Acheta domesticus) cercal sensory system. Comparison of the directional sensitivities of the 9DL interneurons and 10-3 revealed that 3 of the 9DL interneurons have a large degree of overlap in their excitatory receptive fields with that of 10-3. Photoinactivation of any one of these 3 9DL interneurons resulted in a significant decrease in the spike output of 10-3 at its optimal excitatory wind stimulus positions. However, the overall directional sensitivity of 10-3 remained essentially unchanged. Photoinactivation of the one 9DL interneuron which had no overlap in its excitatory receptive field with 10-3 did not affect 10-3's responsiveness to wind stimuli. Results from simultaneous intracellular recordings of 10-3 and one of the 9DL interneurons which had an excitatory influence on 10-3 showed that depolarization of the local interneuron produced an epsp in 10-3, and could elicit several action potentials. Comparison of the morphologies of the 9DL interneurons and 10-3 revealed that the 3 9DL interneurons which had an excitatory influence on 10-3 all had regions of dendritic overlap with this ascending interneuron.

Action Potentials↗

PubMed2003

Wind spectra and the response of the cercal system in the cockroach.

Experiments on the cercal wind-sensing system of the American cockroach, Periplaneta americana, showed that the firing rate of the interneurons coding wind information depends on the bandwidth of random noise wind stimuli. The firing rate was shown to increase with decreases in the stimulus bandwidth, and be independent of changes in the total power of the stimulus with constant spectral composition. A detailed analysis of ethologically relevant stimulus parameters is presented. A phenomenological model of these relationships and their relevance to wind-mediated cockroach behavior is proposed.

Action Potentials↗

PubMed2000

Face temperature and cardiorespiratory responses to wind in thermoneutral and cool subjects exposed to -10 degrees C.

The effects of the thermal state of the body (slightly cool and neutral) and moderate wind speeds on face temperature, blood pressure, respiratory function and pain sensation during cold exposure were studied on eight healthy male subjects. They were dressed in cold-protective clothing and preconditioned at + 20 degrees C (TN) and -5 degrees C (CO) for 60 min, then exposed to -10 degrees C and 0 m x s(-1) (NoW), 1 (W1) and 5 (W5) m x s(-1) wind for 30 min. Thus, each individual was exposed six times. The exposure to wind entailed a combination of strong cooling of the bare face and mild body cooling. The forehead, cheek and nose temperatures decreased during cold exposure, and the decrease was greater at higher air velocities (P < 0.0001). All subjects reported pain sensations at 5 m x s(-1). At the end of exposure only the nose temperature was significantly lower in CO than in TN subjects; it was about 2 degrees C and reached 0 degrees C in two experiments. The systolic and diastolic blood pressure (SBP and DBP, respectively) increased significantly by 7.7 and 5.9 mmHg, respectively, during preconditioning at -5 degrees C, but did not change at + 20 degrees C. SBP and DBP increased during exposure to -10 degrees C in TN by approximately 9 mmHg. However, the total average increase of blood pressure (1-90 min) was similar in TN and CO (SBP 15 mmHg and DBP 13 mmHg). SBP and DBP increased more during exposure to 5 m x s(-1) at -10 degrees C than NoW. Blood pressure responses as observed in this study (SBP and DBP up to 51 and 45 mmHg, respectively) are potential health risks for hypertensive individuals and angina patients. Respiratory functions (FVC, FEV1) were reduced by about 3% by the cold (-5 and -10 degrees C) compared to pre-experiment values. Furthermore, the Wind Chill Index seems to underestimate the cooling power of 5 m x s(-1) at -10 degrees C of bare skin (e.g. face). Therefore it needs to be revised and we suggest that it is expanded to include risk levels for pain sensation.

Adult↗

PubMed1998

Physiological significance of hydrophilic and hydrophobic textile materials during intermittent exercise in humans under the influence of warm ambient temperature with and without wind.

The purpose of this present study was to compare the physiological effects of the hydrophilic and hydrophobic properties of the fabrics investigated in exercising and resting subjects at an ambient temperature of 30 degrees C and a relative humidity of 50% with and without wind. Three kinds of clothing ensemble were tested: wool and cotton blend with high moisture regain (A), 100% cotton with intermediate moisture regain (B), 100% polyester clothing with low moisture regain (C). The experiments were performed using seven young adult women as subjects. They comprised six repeated periods of 10-min exercise on a cycle ergometer at an intensity of 40% maximal oxygen uptake followed by 5 min of rest (20 min for the last rest). The experiments comprised two sessions. During session I (first three repetitions of exercise and rest) the subjects were exposed to an indifferent wind velocity and during session II (last three repetitions of exercise and rest) they were exposed to a wind velocity of 1.5 m x s(-1). Rectal temperature and skin temperatures at eight sites, pulse rate and clothing microclimate were recorded throughout the whole period. The main findings can be summarized as follows: rectal temperature during session II was kept at a significantly lower level in A than in B and C. Clothing microclimate humidity at the chest was significantly lower in A than in B and C during session II. Skin and clothing microclimate temperatures at the chest were significantly lower in A than in B and C during session II. Pulse rate was significantly higher in C than in A and B during sessions I and II. It was concluded that the hydrophilic properties of the fabrics studied were of physiological significance for reducing heat strain during exercise and rest especially when influenced by wind.

Adult↗

PubMed2000

Influence of wind direction on pollen concentration in the atmosphere.

The daily pollen concentration in the atmosphere of Badajoz (SW Spain) was analysed over a 6-year period (1993-1998) using a volumetric aerobiological trap. The results for the main pollination period are compared with the number of hours of wind each day in the four quadrants: 1 (NE), 2 (SE), 3 (SW) and 4 (NW). The pollen source distribution allowed 16 pollen types to be analysed as a function of their distribution in the four quadrants with respect to the location of the trap. Four of them correspond to species growing in an irrigated farmland environment (Amaranthaceae-Chenopodiaceae, Plantago, Scirpus, and Typha), five to riparian and woodland species (Salix, Fraxinus, Alnus, Populus, and Eucalyptus), four to urban ornamentals (Ulmus, Arecaceae, Cupressaceae, and Casuarina), and three which include the most frequent pollen grains of widely distributed species (Poaceae, Quercus, and Olea). The results show that the distribution of the sources and the wind direction play a very major role in determining the pollen concentration in the atmosphere when these sources are located in certain quadrants, and that the widely distributed pollen sources show no relationship with wind direction. In some years the values of the correlations were not maintained, which leads one to presume that, in order to draw significant conclusions and establish clear patterns of the influence of wind direction, a continuous and more prolonged study will be required.

Atmosphere↗

PubMed2006

Atmosphic pollutants study of particles ionic species during high wind speed (>7 m s(-1)) near Taiwan strait in central Taiwan from 2004 to 2005.

This study monitored atmospheric pollutants during high wind speed (> 7 m s(-1)) at two sampling sites: Taichung Harbor (TH) and Wuci traffic (WT) during March 2004 to January 2005 in central Taiwan. The correlation coefficient (R (2)) between TSP, PM(2.5), PM(2.5-10) particle concentration vs. wind speed at the TH and WT sampling site during high wind speed (< 7 m s(-1)) were also displayed in this study. In addition, the correlation coefficients between TSP, PM(2.5) and PM(2.5-10) of ionic species vs. high wind speed were also observed. The results indicated that the correlation coefficient order was TSP > PM(2.5-10) > PM(2.5) for particle at both sampling sites near Taiwan strait. In addition, the concentration of Cl(-), NO(3) (-), SO(4) (2-), NH(4) (+), Mg(2+), Ca(2+) and Na(+) were also analyzed in this study.

Air Pollutants↗