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At least 19 recordsLinked to original sources

PubMed2000

Optimal stopover decisions under wind influence: the effects of correlated winds.

Wind speed and direction have a significant effect on a flying bird's ground speed. Migrants are therefore expected to be sensitive to wind conditions and this should have consequences for optimal strategies of stopover and refuelling. Based on an earlier model of time-minimizing migration which includes wind condition, we investigate the consequences of the temporal correlation of wind conditions. Day-to-day changes in wind conditions are modelled with a two-state Markov process and an expression for the expected speed of migration is derived. The policy of the migrants is described by two parameters: a day t(g) when the birds start to leave whenever favourable conditions occur and a later day t(b)when they leave even in unfavourable winds. The model predicts that in most cases departures should be close to the date which is predicted by a wind-free deterministic model and that the birds should never leave without wind assistance. Only if the probability that the condition remains the same on the following day is close to 1 should the birds leave even in unfavourable conditions shortly after the deterministic optimal date. If the transition matrix is highly asymmetrical, i.e. if it is very probable that unfavourable conditions remain and that favourable conditions will change into unfavourable, then the birds are predicted to start using good winds several days before the deterministic optimal date. An analysis of six years of wind data from two sites in Sweden shows that wind directions on successive days are in fact correlated in all years.

Animals↗

PubMed2002

Spontaneous "second wind" and glucose-induced second "second wind" in McArdle disease: oxidative mechanisms.

BACKGROUND: Blocked glycogen breakdown in McArdle disease impairs oxidative as well as anaerobic metabolism, but the contribution of impaired oxidative phosphorylation to everyday symptoms of McArdle disease remains poorly defined. OBJECTIVE: To evaluate the oxidative implications of the spontaneous second wind and variables that influence the development of this typical feature of McArdle disease. DESIGN: Assessment of exercise and oxidative capacity (.VO(2)) before and after the spontaneous "second wind" and with a glucose infusion after a spontaneous second wind. PATIENTS: Eight patients with complete myophosphorylase deficiency and 1 unique patient with 3% of normal myophosphorylase activity. MAIN OUTCOME MEASURES: Work capacity,.VO(2), heart rate, cardiac output. RESULTS: All patients with complete myophosphorylase deficiency (1) had low peak.VO(2) (mean +/- SD, 13.0 +/- 2.0 mL. kg(-1). min(-1)) in the first 6 to 8 minutes of exercise; (2) achieved a spontaneous second wind with increased exercise capacity between 8 and 12 minutes of exercise due to a more than 25% increase in peak.VO(2) (16.5 +/- 3.1 mL. kg(-1). min(-1)); and (3) with glucose infusion after a spontaneous second wind, experienced a further more than 20% increase in oxidative capacity (.VO(2), 19.9 +/- 3.9 mL. kg(-1). min(-1)). In the patient with residual myophosphorylase,.VO(2) (22.2 mL. kg(-1). min(-1)) in the first 6 to 8 minutes of exercise was approximately 2-fold higher than the mean of patients lacking myophosphorylase, and no significant improvement in exercise and oxidative capacity accompanied prolonged exercise or glucose infusion. CONCLUSIONS: First, the spontaneous second wind and the glucose-induced second second wind in McArdle disease are due to substrate-dependent increases in muscle oxidative capacity. Second, by providing glycogen-derived pyruvate, a small amount of residual myophosphorylase activity normalizes the oxidative deficit of complete myophosphorylase deficiency and virtually eliminates the spontaneous second wind and glucose-induced second second wind.

Adult↗

PubMed1988

Wind-activated thoracic interneurons of the cockroach: I. Responses to controlled wind stimulation.

The cockroach escape response begins with a turn away from a wind puff such as that generated by an approaching predator. The presence and direction of that wind is detected by hairs on the animal's cerci, and this information is conducted to the thoracic ganglia via two populations of giant interneurons. In the thoracic ganglia, the giant interneurons excite a number of interneurons, at least some of which in turn excite motor neurons that control leg movement. In this paper we examine response properties of various thoracic neurons to wind stimuli originating from different directions. Three sets of thoracic neurons were distinguished on the basis of latency. Type A interneurons had short latencies to wind stimuli (1.3-2.25 ms). Type B interneurons had longer latencies (4-6 ms), and motor neurons had the longest latencies (5.6-17.0 ms). Individual type A interneurons either responded equally to wind from all directions or were biased in their response. Directionality was related to the presence of ventral branches near one or both sides of the midline of the ganglion. Cells with ventral median (VM) branches on either side tended to be omnidirectional or front-rear biased, whereas cells with VM branches on only one side were biased to that side. Although several type B interneurons had strong wind responses and were directionally sensitive, they did not have VM branches. We hypothesize that the presence of VM branches in type A interneurons permits connection with ventral giant interneurons, and this connection accounts for their short latency and directional properties. This hypothesis will be tested in the companion paper.

Action Potentials↗

PubMed2006

Predicting the pathway to wind pollination: heritabilities and genetic correlations of inflorescence traits associated with wind pollination in Schiedea salicaria (Caryophyllaceae).

The transition from biotic to abiotic pollination was investigated using Schiedea, a genus exhibiting a remarkable diversity of inflorescence architecture associated with pollination biology. Heritabilities and genetic correlations of inflorescence traits were estimated in gynodioecious Schiedea salicaria (Caryophyllaceae), a species that has likely undergone a recent transition to wind-pollination. Using a partial diallel crossing design, significant narrow-sense heritabilities were detected for inflorescence condensation (h2 = 0.56 to 0.68 in the two sexes) and other traits related to the extent of wind pollination in Schiedea species. Heritabilities were generally higher in hermaphrodites than in females. Strong genetic correlations may constrain the evolution of some inflorescence traits that facilitate wind pollination, such as simultaneous shortening of inflorescence length and elongation of the subtending internode. The presence of significant narrow-sense heritabilities for traits associated with wind pollination suggests, however, that selection for more effective wind pollination in the windy, pollinator-limited environments where S. salicaria grows could lead to the evolution of the highly condensed inflorescences characteristic of other wind-pollinated species of Schiedea.

Biological Evolution↗

PubMed2006

Atmospheric pollutants study of particles and metallic elements during high wind speed (wind speed >6 m/s) near Taiwan Strait around central Taiwan.

The purpose of this study was to characterize metallic elements associated with atmospheric particulate matter in total suspended particulate (TSP), fine particles (particle matter with an aerodynamic diameter of <2.5 microm, PM2.5) and coarse particles (particle matter with an aerodynamic diameter of 2.5-10 microm, PM2.5-10), at high wind speed (wind speed >6 m/s) at Taichung Harbor (TH) and Wuci traffic (WT) in central Taiwan from March to December 2004. The correlation coefficient (R2) between TSP, coarse, fine particulate concentrations versus wind speed at the TH and WT sampling site during high wind speed (>6 m/s) are shown in this study. In addition, the correlation coefficients between TSP, coarse and fine particles of metallic species versus high wind speed were also observed. The results indicated that the correlation coefficient order was TSP> coarse>fine for particles at both sampling sites during high wind speed (>6 m/s) near central Taiwan. In addition, the concentrations of Fe, Zn, Mn, Cu, Pb, Cr, Mg for TSP, coarse and fine particulates were also analysed in this study.

Air Pollutants↗

PubMed2005

[Treatment of 120 cases of pseudobulbar palsy of wind-phlegm type with needling method for dispelling wind and expelling phlegm].

OBJECTIVE: To observe clinical therapeutic effects of needling method for dispelling wind and expelling phlegm on pseudobulbar palsy of wind-phlegm type. METHODS: Two hundred and forty cases of pseudobulbar palsy of wind-phlegm type were randomly divided into an observation group and a control group, 120 cases in each group, and they were treated by needling method for dispelling wind and expelling phlegm, and intravenous dripping of cytidine diphosphate choline injection plus blank needling method, respectively. One month later, main symptoms and signs were systematically compared and assessed. RESULTS: The cured rate and the total effective rate were 40.7% and 89.0% in the observation group respectively, which were superior to 7.6% and 37.0% in the control group (P < 0.01). CONCLUSION: The needling method for dispelling wind and expelling phlegm has obvious therapeutic effect on pseudobulbar palsy of wind-phlegm type.

Acupuncture Points↗

PubMed2005

Floral sex ratio strategy in wind-pollinated monoecious species subject to wind-pollination efficiency and competitive sharing among male flowers as a game.

To explain the floral sex ratio strategy in wind-pollinated monoecious species, we developed four models with special reference to wind-pollination efficiency (WPE) and competitive sharing among male flowers (CSM). WPE is a function that follows a Poisson distribution and explains the frequency of seeds fertilized by an individual via wind-pollination, whereas CSM is defined by the sharing of female flowers among male flowers within the local breeding population. We argued the applicability of the results to the actual tendencies observed in wind-pollinated monoecious species and found that a game model with WPE and CSM was the most applicable. The model predicted that individuals should change their gender expression in the following order: female phase (female flowers only), male phase (male flowers only), and constant male phase (individuals constantly allocate reproductive resources to male flowers, and remaining resources to female flowers), with increasing reproductive resources. However, the trend is likely to be influenced by the variation in the reproductive investment among individuals and the degree of WPE. Thus, large variation and low pollination efficiency enable three phases to co-occur within a population. Actual trends in real populations correspond to our prediction.

Flowers↗

PubMed2000

[Wind tunnel experiment on canopy structural parameters of isolated tree and wind velocity field characters nearby].

The canopy structural parameters(porosity beta and permeability alpha) of isolated tree, and the wind velocity field character nearby were analyzed by wind tunnel experiment. The results show that alpha and beta fitted the function of alpha = beta 0.6, and the wind velocity nearby decreased in ellipsoid contour. The contour increased with increasing tree height and canopy width, and decreased with increasing permeability (or porosity). The isotach became the shape of ellipses or elliptic segments in horizontal and vertical plans.

Trees↗

PubMed2003

Intermittency, scaling, and the Fokker-Planck approach to fluctuations of the solar wind bulk plasma parameters as seen by the WIND spacecraft.

The solar wind provides a natural laboratory for observations of magnetohydrodynamic (MHD) turbulence over extended temporal scales. Here, we apply a model independent method of differencing and rescaling to identify self-similarity in the probability density functions (PDF) of fluctuations in solar wind bulk plasma parameters as seen by the WIND spacecraft. Whereas the fluctuations of speed v and interplanetary magnetic field (IMF) magnitude B are multifractal, we find that the fluctuations in the ion density rho, energy densities B2 and rhov(2) as well as MHD-approximated Poynting flux vB(2) are monoscaling on the time scales up to 26 hr. The single curve, which we find to describe the fluctuations PDF of all these quantities up to this time scale, is non-Gaussian. We model this PDF with two approaches--Fokker-Planck, for which we derive the transport coefficients and associated Langevin equation, and the Castaing distribution that arises from a model for the intermittent turbulent cascade.

Journal Article↗

PubMed1952