682 research outputs found

    Determination of the Quasi-Geoid of Xinjiang and Tibet Areas and the Normal Height of Mt. Everest Based on EGM2008

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    The normal height H* is the height above the quasi-geoid, which coincides with the geoid in the ocean but slightly deviates from the geoid in terrestrial areas. In Mainland China, the height datum system is based on the quasi-geoid. The GPS technique provides the geodetic coordinates of an arbitrary point P on the ground with an accuracy of better than 1 cm. Hence, if the quasi-geoid is given, the normal height can subsequently be determined. In this study, we focus on the determination of the quasi-geoid of the Xinjiang and Tibet areas with a spatial resolution of 5' ¡_ 5' as well as the normal height of Mt. Everest based on a newly released gravity field model EGM2008, which is complete to a degree and order of 2159. We determine the quasi-geoid of Xinjiang and Tibet areas using the digital elevation model of the Shuttle Radar Topography Mission (SRTM), and determine the normal height of Mt. Everest using its geodetic coordinates provided by the Chinese State Bureau of Surveying and Mapping. Based upon the framework of Molodensky theory and EGM2008, we determined the 5' ¡_ 5' quasi-geoid of the Xinjiang and Tibet areas and the normal height of Mt. Everest. Our results show that: (1) the accuracy of the determined 5' ¡_ 5' quasi-geoid of Xinjiang and Tibet areas is around 0.2 m compared with 21 GPS leveling points distributed quite separately in the Xinjiang area (in the Tibet area the GPS/leveling data are not available except for the point at Mt. Everest); (2) the normal height of Mt. Everest is 8847.20 m, which is very close to the value provided by the fourth geodetic surveying campaign on Mt. Everest by the Chinese State Bureau of Surveying and Mapping (the difference is 0.1 m)

    TRPC4 and GIRK channels underlie neuronal coding of firing patterns that reflect Gq/11-Gi/o coincidence signals of variable strengths

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    Transient receptor potential canonical 4 (TRPC4) is a receptor-operated cation channel codependent on both the Gq/11-phospholipase C signaling pathway and Gi/o proteins for activation. This makes TRPC4 an excellent coincidence sensor of neurotransmission through Gq/11- and Gi/o-coupled receptors. In whole-cell slice recordings of lateral septal neurons, TRPC4 mediates a strong depolarizing plateau that shuts down action potential firing, which may or may not be followed by a hyperpolarization that extends the firing pause to varying durations depending on the strength of Gi/o stimulation. We show that the depolarizing plateau is codependent on Gq/11-coupled group I metabotropic glutamate receptors and on Gi/o-coupled γ-aminobutyric acid type B receptors. The hyperpolarization is mediated by Gi/o activation of G protein-activated inwardly rectifying K+ (GIRK) channels. Moreover, the firing patterns, elicited by either electrical stimulation or receptor agonists, encode information about the relative strengths of Gq/11 and Gi/o inputs in the following fashion. Pure Gq/11 input produces weak depolarization accompanied by firing acceleration, whereas pure Gi/o input causes hyperpolarization that pauses firing. Although coincident Gq/11-Gi/o inputs also pause firing, the pause is preceded by a burst, and both the pause duration and firing recovery patterns reflect the relative strengths of Gq/11 versus Gi/o inputs. Computer simulations demonstrate that different combinations of TRPC4 and GIRK conductances are sufficient to produce the range of firing patterns observed experimentally. Thus, concurrent neurotransmission through the Gq/11 and Gi/o pathways is converted to discernible electrical responses by the joint actions of TRPC4 and GIRK for communication to downstream neurons.Fil: Tian, Jin Bin. University of Texas; Estados UnidosFil: Yang, Jane. University Of Toronto. Hospital For Sick Children; CanadáFil: Joslin, William C.. University of Texas; Estados UnidosFil: Flockerzi, Veit. Universitat Saarland; AlemaniaFil: Prescott, Steven A.. University Of Toronto. Hospital For Sick Children; CanadáFil: Birnbaumer, Lutz. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Zhu, Michael X.. University of Texas; Estados Unido

    Repeated 100 Hz TENS for the Treatment of Chronic Inflammatory Hyperalgesia and Suppression of Spinal Release of Substance P in Monoarthritic Rats

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    Transcutaneous electrical nerve stimulation (TENS) has been shown to be an effective measure for pain relief. The aim of the present study was to determine the optimal intensity and interval of repeated 100 Hz TENS for the treatment of chronic inflammatory hyperalgesia in a monoarthritic pain model of the rat, and to assess the changes of the spinal substance P (SP) release in response to TENS treatment. A reliable, reproducible chronic monoarthritic pain model was produced by intra-articular injection of complete Freund's adjuvant (CFA) at single ankle joint. The efficacy of 100 Hz TENS treatments with different frequencies and intensities was compared. In the acute period (within 3 weeks) of monoarthritis, twice-a-week schedule of TENS reduced the swelling of the inflamed ankle significantly. In the stable period (4–9 weeks), however, once-a-week schedule produced a significantly better therapeutic effect on both inflammation and arthritic hyperalgesia than that of twice- or five-times-a-week schedule. Using three levels of intensity of TENS, we found that the weaker (1-1-2 mA) stimulation produced significantly better therapeutic effects. Repeated TENS produced a reduction of SP content in spinal perfusate in parallel with the progressive reduction of the arthritic pain scores. Our results suggest that (i) consecutive TENS treatments produced cumulative effect for chronic hyperalgesia, (ii) for chronic inflammatory hyperalgesia, a weaker intensity and more sparsely arranged treatment schedule may produce better therapeutic effect and (iii) a decrease in SP release may serve as one of the possible neurochemical mechanisms underlying the therapeutic effects of multiple TENS treatments on chronic inflammatory hyperalgesia

    Experimental Free-Space Distribution of Entangled Photon Pairs over a Noisy Ground Atmosphere of 13km

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    We report free-space distribution of entangled photon pairs over a noisy ground atmosphere of 13km. It is shown that the desired entanglement can still survive after the two entangled photons have passed through the noisy ground atmosphere. This is confirmed by observing a space-like separated violation of Bell inequality of 2.45±0.092.45 \pm 0.09. On this basis, we exploit the distributed entangled photon source to demonstrate the BB84 quantum cryptography scheme. The distribution distance of entangled photon pairs achieved in the experiment is for the first time well beyond the effective thickness of the aerosphere, hence presenting a significant step towards satellite-based global quantum communication.Comment: 4 pages, 3 figure

    Aboveground net primary productivity of vegetation along a climate-related gradient in a Eurasian temperate grassland: spatiotemporal patterns and their relationships with climate factors

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    Accurate assessments of spatiotemporal patterns in net primary productivity and their links to climate are important to obtain a deeper understanding of the function, stability and sustainability of grassland ecosystems. We combined a satellite-derived NDVI time-series dataset and field-based samples to investigate spatiotemporal patterns in aboveground net primary productivity (ANPP), and we examined the effect of growing season air temperate (GST) and precipitation (GSP) on these patterns along a climaterelated gradient in an eastern Eurasian grassland. Our results indicated that the ANPP fluctuated with no significant trend during 2001-2012. The spatial distribution of ANPP was heterogeneous and decreased from northeast to southwest. The interannual changes in ANPP were mainly controlled by year-to-year GSP; a strong correlation of interannual variability between ANPP and GSP was observed. Similarly, GSP strongly influenced spatial variations in ANPP, and the slopes of fitted linear functions of the GSP-ANPP relationship increased from arid temperate desert grassland to humid meadow grassland. An exponential function could be used to fit the GSP-ANPP relationship for the entire region. An improved moisture index that combines the effects of GST and GSP better explained the variations in ANPP compared with GSP alone. In comparisons with the previous studies, we found that the relationships between spatiotemporal variations in ANPP and climate factors were probably scale dependent. We imply that the quantity and spatial range of analyzed samples contribute to these different results. Multi-scale studies are necessary to improve our knowledge of the response of grassland ANPP to climate change.ArticleENVIRONMENTAL EARTH SCIENCES.76(1):56(2017)journal articl
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