269 research outputs found

    High speed protocols for dual bus and dual ring network architectures

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    In this dissertation, two channel access mechanisms providing fair and bandwidth efficient transmission on dual bus and dual ring networks with high bandwidth-latency product are proposed. In addition, two effective priority mechanisms are introduced to meet the throughput and delay requirements of the diverse arrays of applications that future high speed networks must support. For dual bus architectures, the Buffer Insertion Bandwidth Balancing (BI_BWB) mechanism and the Preemptive priority Bandwidth Balancing (P_BI_BWB) mechanism are proposed. BI_BWB can significantly improve the delay performance of remote stations. It achieves that by providing each station with a shift register into which the station can temporarily store the upstream stations\u27 transmitted packets and replace these packets with its own transmissions. P_BI_BWB, an enhancement of BI_BWB, is designed to introduce effective preemptive priorities. This mechanism eliminates the effect of low priority on high priority by buffering the low priority traffic into a shift register until the transmission of the high priority traffic is complete. For dual ring architectures, the Fair Bandwidth Allocation Mechanism (FBAM) and the Effective Priority Bandwidth Balancing (EP_BWB) mechanism are introduced. FBAM allows stations to reserve channel bandwidth on a continuous basis rather than wait until bandwidth starvation is observed. Consequently, FBAM does not have to deal with the difficult issue of identifying starvation, a serious drawback of other access mechanisms such as the Local and Global Fairness Algorithms (LFA and GFA, respectively). In addition, its operation requires a significantly smaller number of control bits in the access control field of the slot and its performance is less sensitive to system parameters. Moreover, FBAM demonstrates Max-Min flow control properties with respect to the allocation of bandwidth among competing traffic streams, which is a significant advantage of FBAM over all the previously proposed channel access mechanisms. EP_BWB, an enhancement of FBAM to support preemptive priorities, minimizes the effect of low priority on high priority and supports delay-sensitive traffic by enabling higher priority classes to preempt the transmissions of lower priority classes. Finally, the great potential of EP_BWB to support the interconnection of base stations on a distributed control wireless PCN carrying voice and data traffic is demonstrated

    Transcatheter Closure vs Surgical Closure of Ventricular Septal Defect in China: A Meta-Analysis

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    Objective: To compare the curative effect, safety and medical cost of transcatheter closure and surgical closure in ventricular septal defect in China,so as to provide references for treatment plans of ventricular septal defect in clinic medicine. Methods: Chinese literature databases such as CBM, VIP, CNKI, Wan Fang and English literature databases such as PubMed, Ovid and EBSCO were searched from the date of their establishment to June 2015 for collecting the related articles, the collected articles were screened, extracted, evaluated, and analyzed by using Revman5. 3 software. Results: 23 articles (16 Chinese articles, 7 English articles) met the inclusion criteria,transcatheter closure (TC) group included 2801 cases,surgical closure (SC) group included 3,086 cases. Meta-analysis results showed as following:(a) operation success rate:TC group was lower than SC group (RR=0.98, 95% CI=0.96~0.99, P = 0.008);(b) operation complication rate:TC group was lower than SC group (RR=0.62, 95% CI=0.46~0.84, P=0.002);(c) operation immediate residual shunt rate:TC group was lower than SC group (RR=0.69, 95% CI = 0.51~ 0.95, P=0.02);(d) operation time:TC group was shorter than SC group (SMD= -2.87, 95% CI = -3.60 ~ -2.13, P<0.00001);(e) length of hospital stay:TC group was shorter than SC group (SMD= -1.55, 95% CI=-2.14 ~ -0.95, P<0.00001);(6) hospitalization expenses:TC group was higher than SC group (SMD=1.02, 95% CI=0.12~1.93, P=0.03). Conclusion: TC is lower than SC in operation success rate,operation complication rate and operation immediate residual shunt rate; and TC is shorter than SC in operation time and length of hospital stay;but TC is higher than SC in the hospitalization expenses. Thus, transcatheter closure can be used as an alternative to surgical treatment in the range of indication

    Interleukin-4 suppresses the expression of macrophage NADPH oxidase heavy chain subunit (gp91-phox)

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    AbstractThe production of superoxide anion by NADPH oxidase is a principal nonspecific bactericidal activity of macrophages and neutrophils in host defense. However, exuberant production of superoxide anion also damages host tissues. Cloning and DNA sequencing of the 91 kDa subunit (gp91-phox) open reading frame indicated a high degree of sequence conservation, greater than 90% in nucleotide and amino acid sequences, between the porcine and human cDNAs. We show in pigs that interleukin-4 (IL-4), a T lymphocyte cytokine which plays a major role in mediating antibody responses to pathogens, suppresses superoxide anion production in macrophages by specifically reducing the level of mRNA encoding gp91-phox. Messenger RNA levels are suppressed approx. 70% within 4 h and persist for 24 h without any change in the rate of mRNA turnover. Nuclear run-on analysis showed that IL-4 did not alter the rate of gp91-phox gene transcription under conditions in which IL-1β transcription was inhibited. These results indicate that IL-4 suppresses the inflammatory response of macrophages by mechanisms that include post-transcriptional regulation of the 91 kDa catalytic subunit of NADPH oxidase, and transcriptional regulation of inflammatory cytokine expression

    Winner versus Loser: Time-Varying Performance And Dynamic Conditional Correlation

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    Using multi-factor models in OLS and GARCH-M methodology, this paper provides a cross-sectional and time-series investigation of conditional and unconditional expected returns of real REITs index momentum portfolios against real estate property, large-cap stock small-cap stock, and bond index in USA. The expected returns and dynamic conditional correlations between REITs and those of other financial and tangible assets vary in period 1989-2010. REITs returns exhibit a higher correlation with up move of financial market, but a lower correlation in market downturns. REITs may possibly provide diversification benefits to multi-asset investment portfolio. We find that the performances of momentum returns are different from the NAREIT index, and display asymmetric volatility as well. Additionally, we find evidence that REITs momentum returns are varying between winner and loser by Wald test. The results of regressions also indicate that REITs return exhibits the greater sensitivity to large- and small-cap stock index, and less closely with those of bond and real estate index. The results also suggest that REITs not be viewed as a complete substitute for investment in tangible property of real estate

    Performance of solar-induced chlorophyll fluorescence in estimating water-use efficiency in a temperate forest

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    © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Remote Sensing 10 (2018): 796, doi:10.3390/rs10050796.Water-use efficiency (WUE) is a critical variable describing the interrelationship between carbon uptake and water loss in land ecosystems. Different WUE formulations (WUEs) including intrinsic water use efficiency (WUEi), inherent water use efficiency (IWUE), and underlying water use efficiency (uWUE) have been proposed. Based on continuous measurements of carbon and water fluxes and solar-induced chlorophyll fluorescence (SIF) at a temperate forest, we analyze the correlations between SIF emission and the different WUEs at the canopy level by using linear regression (LR) and Gaussian processes regression (GPR) models. Overall, we find that SIF emission has a good potential to estimate IWUE and uWUE, especially when a combination of different SIF bands and a GPR model is used. At an hourly time step, canopy-level SIF emission can explain as high as 65% and 61% of the variances in IWUE and uWUE. Specifically, we find that (1) a daily time step by averaging hourly values during daytime can enhance the SIF-IWUE correlations, (2) the SIF-IWUE correlations decrease when photosynthetically active radiation and air temperature exceed their optimal biological thresholds, (3) a low Leaf Area Index (LAI) has a negative effect on the SIF-IWUE correlations due to large evaporation fluxes, (4) a high LAI in summer also reduces the SIF-IWUE correlations most likely due to increasing scattering and (re)absorption of the SIF signal, and (5) the observation time during the day has a strong impact on the SIF-IWUE correlations and SIF measurements in the early morning have the lowest power to estimate IWUE due to the large evaporation of dew. This study provides a new way to evaluate the stomatal regulation of plant-gas exchange without complex parameterizations.This research was supported by U.S. Department of Energy Office of Biological and Environmental Research Grant DE-SC0006951, National Science Foundation Grants DBI 959333 and AGS-1005663, and the University of Chicago and the MBL Lillie Research Innovation Award to Jianwu Tang. This study was also supported by the open project grant (LBKF201701) of Key Laboratory of Land Surface Pattern and Simulation, Chinese Academy of Sciences

    A large-scale methane model by incorporating the surface water transport

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    Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Biogeosciences 121 (2016): 1657–1674, doi:10.1002/2016JG003321.The effect of surface water movement on methane emissions is not explicitly considered in most of the current methane models. In this study, a surface water routing was coupled into our previously developed large-scale methane model. The revised methane model was then used to simulate global methane emissions during 2006–2010. From our simulations, the global mean annual maximum inundation extent is 10.6 ± 1.9 km2 and the methane emission is 297 ± 11 Tg C/yr in the study period. In comparison to the currently used TOPMODEL-based approach, we found that the incorporation of surface water routing leads to 24.7% increase in the annual maximum inundation extent and 30.8% increase in the methane emissions at the global scale for the study period, respectively. The effect of surface water transport on methane emissions varies in different regions: (1) the largest difference occurs in flat and moist regions, such as Eastern China; (2) high-latitude regions, hot spots in methane emissions, show a small increase in both inundation extent and methane emissions with the consideration of surface water movement; and (3) in arid regions, the new model yields significantly larger maximum flooded areas and a relatively small increase in the methane emissions. Although surface water is a small component in the terrestrial water balance, it plays an important role in determining inundation extent and methane emissions, especially in flat regions. This study indicates that future quantification of methane emissions shall consider the effects of surface water transport.The finacial support for this work is from the Open Fund of State Key Laboratory of Remote Sensing Science of China (OFSLRSS201501); 2 Supported by the Fundamental Research Funds for the Central Universities (20720160109).2016-12-2

    Comparison of phenology estimated from reflectance-based indices and solar-induced chlorophyll fluorescence (SIF) observations in a temperate forest using GPP-based phenology as the standard

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    © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Remote Sensing 10 (2018): 932, doi:10.3390/rs10060932.We assessed the performance of reflectance-based vegetation indices and solar-induced chlorophyll fluorescence (SIF) datasets with various spatial and temporal resolutions in monitoring the Gross Primary Production (GPP)-based phenology in a temperate deciduous forest. The reflectance-based indices include the green chromatic coordinate (GCC), field measured and satellite remotely sensed Normalized Difference Vegetation Index (NDVI); and the SIF datasets include ground-based measurement and satellite-based products. We found that, if negative impacts due to coarse spatial and temporal resolutions are effectively reduced, all these data can serve as good indicators of phenological metrics for spring. However, the autumn phenological metrics derived from all reflectance-based datasets are later than the those derived from ground-based GPP estimates (flux sites). This is because the reflectance-based observations estimate phenology by tracking physiological properties including leaf area index (LAI) and leaf chlorophyll content (Chl), which does not reflect instantaneous changes in phenophase transitions, and thus the estimated fall phenological events may be later than GPP-based phenology. In contrast, we found that SIF has a good potential to track seasonal transition of photosynthetic activities in both spring and fall seasons. The advantage of SIF in estimating the GPP-based phenology lies in its inherent link to photosynthesis activities such that SIF can respond quickly to all factors regulating phenological events. Despite uncertainties in phenological metrics estimated from current spaceborne SIF observations due to their coarse spatial and temporal resolutions, dates in middle spring and autumn—the two most important metrics—can still be reasonably estimated from satellite SIF. Our study reveals that SIF provides a better way to monitor GPP-based phenological metrics.This research was supported by U. S. Department of Energy Office of Biological and Environmental Research Grant DE-SC0006951, National Science Foundation Grants DBI 959333 and AGS-1005663, and the University of Chicago and the MBL Lillie Research Innovation Award to Jianwu Tang and China Scholarship Council No. 201506190095 to Z. Liu. Xiaoliang Lu was also supported by the open project grant (LBKF201701) of Key Laboratory of Land Surface Pattern and Simulation, Chinese Academy of Sciences

    Application progress of machine vision technology in the field of modern agricultural equipment

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    With the rapid progress of image processing algorithms and computer equipment, the development of machine vision technology in the field of modern agricultural equipment is in the ascendant, and major application results have been obtained in many production links to improve the efficiency and automation of agricultural production. In the face of China, the world's largest agricultural market, agricultural machine vision equipment undoubtedly has tremendous development potential and market prospects. This paper introduces the research and application of machine vision technology in agricultural equipment in the fields of agricultural product sorting, production automation, pest control, picking machinery and navigation and positioning, analyzes and summarizes the current problems, and looks forward to the future development trend

    Acoustofluidic Engineering Functional Vessel-on-a-Chip

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    Construction of in vitro vascular models is of great significance to various biomedical research, such as pharmacokinetics and hemodynamics, thus is an important direction in tissue engineering. In this work, a standing surface acoustic wave field was constructed to spatially arrange suspended endothelial cells into a designated patterning. The cell patterning was maintained after the acoustic field was withdrawn by the solidified hydrogel. Then, interstitial flow was provided to activate vessel tube formation. Thus, a functional vessel-on-a-chip was engineered with specific vessel geometry. Vascular function, including perfusability and vascular barrier function, was characterized by beads loading and dextran diffusion, respectively. A computational atomistic simulation model was proposed to illustrate how solutes cross vascular lipid bilayer. The reported acoustofluidic methodology is capable of facile and reproducible fabrication of functional vessel network with specific geometry. It is promising to facilitate the development of both fundamental research and regenerative therapy
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