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101.
Whereas the use of discrete pitch intervals is characteristic of most musical traditions, the size of the intervals and the way in which they are used is culturally specific. Here we examine the hypothesis that these differences arise because of a link between the tonal characteristics of a culture's music and its speech. We tested this idea by comparing pitch intervals in the traditional music of three tone language cultures (Chinese, Thai and Vietnamese) and three non-tone language cultures (American, French and German) with pitch intervals between voiced speech segments. Changes in pitch direction occur more frequently and pitch intervals are larger in the music of tone compared to non-tone language cultures. More frequent changes in pitch direction and larger pitch intervals are also apparent in the speech of tone compared to non-tone language cultures. These observations suggest that the different tonal preferences apparent in music across cultures are closely related to the differences in the tonal characteristics of voiced speech.  相似文献   
102.
Gene frequencies at 20 blood group and protein polymorphism loci ( A, C, D, K, P, Q, U, Al, Tf, Pi, Xk, Es, Gc, PGD, CA, Cat, PGM, AP, Hb and PHI ) are given for seven horse breeds in the United States (Thoroughbred, Arabian, Standard bred, Morgan, Quarter Horse, Paso Fino and Peruvian Paso). These data are used to calculate that the battery of tests is at least 96% effective for recognizing incorrect paternity in these breeds. In addition to paternity testing, these tests can be applied to studies of breed relationships.  相似文献   
103.
A survey of injuries to dancers was commissioned by the National Organisation of Dance and Mime. Questionnaires asking about chronic and recent injuries were sent to 188 dancers and completed by 141 dancers from seven professional ballet and modern dance companies in the United Kingdom (75% response rate). It was found that of the 141 dancers, 67 (47%) had experienced a chronic injury and 59 (42%) an injury in the previous six months that had affected their dancing. A high proportion of injuries to the soft tissues had not responded to treatment. With correct treatment such injuries should usually heal completely. Dancers are aware of the high rate of injuries and also of procedures that might help to prevent injury--for example, dancing on floors that are sprung and in warmer studios; teachers'' and choreographers'' awareness of a dancer''s limitations and the need for rest and adequate treatment when an injury occurs.  相似文献   
104.
The cytoplasmic domain of the rosette terminal complex has been imaged in situ in patches of plasma membrane isolated from tobacco BY-2 protoplasts. By partially extracting the plasma membrane lipids, cellulose microfibrils were observed through the plasma membrane. Rosette terminal complexes were identified on the basis of their association with the ends of these cellulose microfibrils. The cytoplasmic domain of the rosette terminal complex has been shown to be hexagonal in shape and has been measured to be 45-50 nm in diameter and 30-35 nm tall. These findings demonstrate that the terminal complex does indeed have a substantial cytoplasmic component, and that the hexagonal array observed in the lipid bilayer by freeze fracture is actually only a small part of the overall complex. These findings will allow better modeling of the terminal complex and may facilitate predictions of how many proteins are associated with the rosette terminal complex in vivo.  相似文献   
105.
106.
Global‐scale studies suggest that dryland ecosystems dominate an increasing trend in the magnitude and interannual variability of the land CO2 sink. However, such analyses are poorly constrained by measured CO2 exchange in drylands. Here we address this observation gap with eddy covariance data from 25 sites in the water‐limited Southwest region of North America with observed ranges in annual precipitation of 100–1000 mm, annual temperatures of 2–25°C, and records of 3–10 years (150 site‐years in total). Annual fluxes were integrated using site‐specific ecohydrologic years to group precipitation with resulting ecosystem exchanges. We found a wide range of carbon sink/source function, with mean annual net ecosystem production (NEP) varying from ‐350 to +330 gCm?2 across sites with diverse vegetation types, contrasting with the more constant sink typically measured in mesic ecosystems. In this region, only forest‐dominated sites were consistent carbon sinks. Interannual variability of NEP, gross ecosystem production (GEP), and ecosystem respiration (Reco) was larger than for mesic regions, and half the sites switched between functioning as C sinks/C sources in wet/dry years. The sites demonstrated coherent responses of GEP and NEP to anomalies in annual evapotranspiration (ET), used here as a proxy for annually available water after hydrologic losses. Notably, GEP and Reco were negatively related to temperature, both interannually within site and spatially across sites, in contrast to positive temperature effects commonly reported for mesic ecosystems. Models based on MODIS satellite observations matched the cross‐site spatial pattern in mean annual GEP but consistently underestimated mean annual ET by ~50%. Importantly, the MODIS‐based models captured only 20–30% of interannual variation magnitude. These results suggest the contribution of this dryland region to variability of regional to global CO2 exchange may be up to 3–5 times larger than current estimates.  相似文献   
107.
We integrated soil models with an established ecosystem process model (SIPNET, simplified photosynthesis and evapotranspiration model) to investigate the influence of soil processes on modelled values of soil CO2 fluxes (R Soil). Model parameters were determined from literature values and a data assimilation routine that used a 7-year record of the net ecosystem exchange of CO2 and environmental variables collected at a high-elevation subalpine forest (the Niwot Ridge AmeriFlux site). These soil models were subsequently evaluated in how they estimated the seasonal contribution of R Soil to total ecosystem respiration (TER) and the seasonal contribution of root respiration (R Root) to R Soil. Additionally, these soil models were compared to data assimilation output of linear models of soil heterotrophic respiration. Explicit modelling of root dynamics led to better agreement with literature values of the contribution of R Soil to TER. Estimates of R Soil/TER when root dynamics were considered ranged from 0.3 to 0.6; without modelling root biomass dynamics these values were 0.1–0.3. Hence, we conclude that modelling of root biomass dynamics is critically important to model the R Soil/TER ratio correctly. When soil heterotrophic respiration was dependent on linear functions of temperature and moisture independent of soil carbon pool size, worse model-data fits were produced. Adding additional complexity to the soil pool marginally improved the model-data fit from the base model, but issues remained. The soil models were not successful in modelling R Root/R Soil. This is partially attributable to estimated turnover parameters of soil carbon pools not agreeing with expected values from literature and being poorly constrained by the parameter estimation routine. We conclude that net ecosystem exchange of CO2 alone cannot constrain specific rhizospheric and microbial components of soil respiration. Reasons for this include inability of the data assimilation routine to constrain soil parameters using ecosystem CO2 flux measurements and not considering the effect of other resource limitations (for example, nitrogen) on the microbe biomass. Future data assimilation studies with these models should include ecosystem-scale measurements of R Soil in the parameter estimation routine and experimentally determine soil model parameters not constrained by the parameter estimation routine.  相似文献   
108.

Background  

Nitric oxide and prostaglandin E2 (PGE2play pivotal roles in both the pathogenesis of osteoarthritis and catabolic processes in articular cartilage. These mediators are influenced by both IL-1β and mechanical loading, and involve alterations in the inducible nitric oxide synthase (iNOS) and cyclo-oxygenase (COX)-2 enzymes. To identify the specific interactions that are activated by both types of stimuli, we examined the effects of dynamic compression on levels of expression of iNOS and COX-2 and involvement of the p38 mitogen-activated protein kinase (MAPK) pathway.  相似文献   
109.
Carbon isotopes in terrestrial ecosystem pools and CO2 fluxes   总被引:3,自引:1,他引:2  
Stable carbon isotopes are used extensively to examine physiological, ecological, and biogeochemical processes related to ecosystem, regional, and global carbon cycles and provide information at a variety of temporal and spatial scales. Much is known about the processes that regulate the carbon isotopic composition (delta(13)C) of leaf, plant, and ecosystem carbon pools and of photosynthetic and respiratory carbon dioxide (CO(2)) fluxes. In this review, systematic patterns and mechanisms underlying variation in delta(13)C of plant and ecosystem carbon pools and fluxes are described. We examine the hypothesis that the delta(13)C of leaf biomass can be used as a reference point for other carbon pools and fluxes, which differ from the leaf in delta(13)C in a systematic fashion. Plant organs are typically enriched in (13)C relative to leaves, and most ecosystem pools and respiratory fluxes are enriched relative to sun leaves of dominant plants, with the notable exception of root respiration. Analysis of the chemical and isotopic composition of leaves and leaf respiration suggests that growth respiration has the potential to contribute substantially to the observed offset between the delta(13)C values of ecosystem respiration and the bulk leaf. We discuss the implications of systematic variations in delta(13)C of ecosystem pools and CO(2) fluxes for studies of carbon cycling within ecosystems, as well as for studies that use the delta(13)C of atmospheric CO(2) to diagnose changes in the terrestrial biosphere over annual to millennial time scales.  相似文献   
110.
Bowling AJ  Vaughn KC 《Protoplasma》2008,232(3-4):153-163
Summary. The tendrils of Virginia creeper (Parthenocissus quinquefolia) do not coil around their supports. Rather, they adhere to supporting objects by flattening against the support surface and secreting an adhesive compound which firmly glues the tendril to the support. In this study, microscopic and immunocytochemical techniques were utilized to determine the nature of this adhesive. Following touch stimulation, epidermal cells of the tendril elongate toward the support substrate, becoming papillate in morphology. Following contact with the support surface, an adhesive is produced at the base of the papillate cells. The adhesive appears as a highly heterogeneous, raftlike structure and consists of pectinaceous, rhamnogalacturonan (RG) I-reactive components surrounding a callosic core. In addition, more mobile components, composed of arabinogalactans and mucilaginous pectins, intercalate both the support and the tendril, penetrating the tendril to the proximal ends of the papillate cells. Following adherence to the support, the anticlinal walls of the papillate cells are devoid of RG I side-chain reactivity, indicating that extensive debranching of RG I molecules has taken place. Furthermore, a large amount of RG I backbone reactivity was observed in the contact area. These results may indicate that the debranched RG I molecules diffuse into and permeate the contact region, forming an integral part of the adhesive compound. These results indicate that Virginia creeper adheres to objects by a composite adhesive structure consisting of debranched RG I, callose, and other, less-well characterized mucilaginous pectins and that this structure subsequently becomes lignified and very weather-resistant upon the ultimate senescence of the tendril. Correspondence: Kevin C. Vaughn, USDA-ARS-SWSRU, P.O. Box 350, Stoneville, MS 38776, U.S.A.  相似文献   
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