227 research outputs found

    Land Distributional and Income Effects of the Chinese Land Rental Market

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    Using panel data of 450 farm households for the period of 1996-2001 in Zhejiang, China, we measured land distributional effect and income effect of the land rental market. It is found that the rental market had contributed for a less equal land distribution among the households, and for the concentration of land to households with higher efficiency. With a land rental market in a dynamic economic development process, improvements in overall production efficiency of the households, however, mainly come from the reduction of land abandonment and the contribution from land changing hands is very limited.Land rental market, distribution, efficiency, land abandonment, Land Economics/Use, Q12, O1, Q15,

    System Frequency Support of Permanent Magnet Synchronous Generator-Based Wind Power Plant

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    With ever-increasing penetration of wind power into modern electric grids all over the world, a trending replacement of conventional synchronous generators by large wind power plants will likely result in the poor overall frequency regulation performance. On the other hand, permanent magnet synchronous generator wind Turbine System (PMSG-WTG) with full power back to back converters tends to become one of the most promising wind turbine technologies thanks to various advantages. It possesses a significant amount of kinetic energy stored in the rotating mass of turbine blades, which can be utilized to enhance the total inertia of power system. Additionally, the deloaded operation and decoupled control of active and reactive power make it possible for PMSG-WTG to provide a fast frequency regulation through full-power converter. First of all, a comprehensive and in-depth survey is conducted to analyze the motivations for incorporating the inertial response and frequency regulation of VSWT into the system frequency regulation. Besides, control classifications, fundamental control concepts and advanced control schemes implemented for auxiliary frequency support of individual WT or wind power plant are elaborated along with a comparison of the potential frequency regulation capabilities of four major types of WTs. Secondly, a Controls Advanced Research Turbine2-Permanent Magnet Synchronous Generator wind turbine (CART2-PMSG) integrated model representing the typical configuration and operation characteristics of PMSG-WT is established in Matlab/Simulink,. Meanwhile, two different rotor-side converter control schemes, including rotor speed-based control and active power-based control, are integrated into this CART2-PMSG integrated model to perform Maximum Power Point Tracking (MPPT) operation over a wide range of wind speeds, respectively. Thirdly, a novel comprehensive frequency regulation (CFR) control scheme is developed and implemented into the CART2-PMSG model based on rotor speed control. The proposed control scheme is achieved through the coordinated control between rotor speed and modified pitch angle in accordance with different specified wind speed modes. Fourth, an improved inertial control method based on the maximum power point tracking operation curve is introduced to boost the overall frequency support capability of PMSG-WTGs based on rotor speed control. Fifth, a novel control method based on the torque limit (TLC) is proposed for the purpose of maximizing the wind turbine (WT)\u27s inertial response. To avoid the SFD caused by the deloaded operation of WT, a small-scale battery energy storage system (BESS) model is established and implemented to eliminate this impact and meanwhile assist the restoration of wind turbine to MPPT mode by means of coordinated control strategy between BESS and PMSG-WTG. Last but not the least, all three types of control strategies are implemented in the CART2-PMSG integrated model based on rotor speed control or active power control respectively to evaluate their impacts on the wind turbine\u27s structural loads during the frequency regulation process. Simulation results demonstrate that all the proposed methods can enhance the overall frequency regulation performance while imposing very slight negative impact on the major mechanical components of the wind turbine

    Do Chinese stock markets share common information arrival processes?

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    According to the Mixture of Distributions Hypothesis (MDH), returns volatility and trading volume are driven by a common news arrival variable. Consequently, these two variables should be correlated. This paper extends, and to some extent, globalises the concept of a common information arrival process by hypothesising that this variable drives daily price (returns) volatility and trading volume changes in different financial markets. An implication is that returns volatility in one stock market should show positive and contemporaneous correlation with returns volatility in another stock market. This paper tests this implication using data from three separate, but geographically close, stock markets (Shenzhen, Shanghai and Hong Kong). A problem in the usual testing procedure is the likelihood that the news arrival process has long memory. This means that both volatility and volume (or external volatility) will have long memory and consequently, contemporaneous correlation between these variables is likely to be incorrectly rejected in cases where the test equation does not account for long memory. This paper uses fractionally integrated GARCH (FIGARCH) to test and account for long memory. The analysis finds that there is contemporaneous correlation between returns volatility in these stock markets and confirms the presence of long memory effects.mixture of distributions hypothesis, news arrival process, FIGARCH, volatility, long memory

    The Long-run Impact of Different Exchange Rates on the Projected Agricultural Income of an Export Dependent Region of the UK.

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    This paper evaluates the effects of different exchange rate scenarios on projections for agricultural incomes and prices in a small highly export dependent region, NI. The modelling system used in the analysis is designed to capture the complexities of the relationship between exchange rates and agricultural prices and incomes. The system models not only the main agricultural sectors in NI but also the demand for and supply of agricultural commodities in the EU and beyond. This is important, given that NI is a price taker and the EU is the main export destination for its agricultural production. The analysis serves to underline the importance of exchange rates for the NI agricultural economy. When the euro is weak against sterling then agricultural sector incomes are substantially lower than when the euro is strong against sterling. Approximately, a one per cent weakening/strengthening of the euro against sterling is projected to reduce/increase aggregate net receipts in the dairy, beef and sheep sectors by one per cent. This means that exchange rate movements, which are outside the control of the agricultural community, have a dramatic affect on agricultural incomes in NI. This conclusion should be considered against the backdrop of a 28% drop (approx.) in the value of the euro against the pound that has occurred since 1995. The impact of exchange rate movements on producer prices appears to be less pronounced.

    Do EU direct payments to beef producers belong in the ‘blue box’?

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    In the Uruguay Round Agreement on Agriculture, so-called ‘blue box’ support measures were exempted from reduction commitments, provided they were delivered under ‘production-limiting’ programs. Although classified as ‘blue box’, the EU system of direct payments (DP) to beef farmers imposes ‘claim-limiting’ restrictions rather than ‘production-limiting’ restrictions, allowing farmers to keep additional animals over and above the number upon which they are eligible to claim DP. The present paper provides empirical evidence that EU direct payments capitalise into the market prices of male calves and young steers in Ireland. It is also likely that DP capitalises into the prices of beef cows and heifers. Given this capitalisation process, some farmers can obtain ‘capitalised’ DP on animals produced over and above the ‘claim-limiting’ restrictions, by selling these animals through auction markets. Thus, ‘capitalised’ DP probably encourages production over and above the limiting measures.Agricultural and Food Policy, Livestock Production/Industries,

    Meteorological Change and Impacts on Air Pollution: Results From North China

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    There have been speculations that the severe air pollution experienced in North China was the act of meteorological change in general and a decreasing northerly wind in particular. We conduct a retrospective analysis on 1979–2016 reanalysis data from ERA‐Interim of European Centre for Medium‐Range Weather Forecasts over a region in North China to detect meteorological changes over the 38 years. No significant reduction in the northerly wind within the mixing layer is detected. Statistically significant increases are detected in the surface temperature, boundary layer height and dissipation, and significant decreases in relative humidity in the region between the first and second 19‐year periods from 1979 to 2016. We build regression models of PM2.5 on the meteorological variables using data in 2014, 2015, and 2016 to quantify effects of the meteorological changes between the two 19‐year periods on PM2.5 under the emission scenarios of 2014–2016. It is found that despite the warming, dew point temperature had been largely kept under control as the region had gotten dryer. This made the effects of temperature warming largely favorable to PM2.5 reduction as it enhances boundary layer height and dissipation. It is found that the meteorological changes would lead to 1.29% to 2.76% reduction in annual PM2.5 averages with January, March, and December having more than 4% reduction in the 3 years. Thus, the meteorological change in North China had helped alleviate PM2.5 to certain extent and should not be held responsible for the regional air pollution problem.Key PointsMeteorological changes led to 1.9% to 2.7 percent% reduction in annual PM2.5 averages over North China 2014 to 2016 driven by temperature warmingSignificant increases are detected in the surface temperature, boundary layer height, and dissipation and decreases in relative humidityThe meteorological change should not be held responsible for the regional air pollution problem in North ChinaPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156450/3/jgrd56226_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156450/2/jgrd56226.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156450/1/jgrd56226-sup-0001-Figure_SI-S01.pd

    Measuring the Sensitivity of the Northern Ireland Protocol on the All-Ireland Agri-Food Supply Chain

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    Publication history: Published - 29 March 2023The agri-food sectors in Northern Ireland (NI) and Ireland (IRL) have become more integrated with more investments from IRL in the north and advances in all Ireland cooperation on animal health and welfare, and disease control. However, as both jurisdictions are considered structurally similar and both have a large dairy and beef sector, they are competing in the Great Britain (GB) market for agrifood products. When considering the island of Ireland agri-food sectors in the context of Brexit and the NI Protocol, there will be clear winners and losers under different Brexit and NI protocol scenarios. What constitutes a relatively “good” economic outcome for NI farmers may come at the expense of IRL farmers, while relatively “good” economic outcomes for IRL farmers may amplify negative outcomes for NI farmers. This paper analyses the impacts of the NI Protocol in terms of what it means for the agri-food sectors in IRL, NI, but also for the island of Ireland (ISL) as a whole

    The sea lamprey Petromyzon marinus genome reveals the early origin of several chemosensory receptor families in the vertebrate lineage

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    <p>Abstract</p> <p>Background</p> <p>In gnathostomes, chemosensory receptors (CR) expressed in olfactory epithelia are encoded by evolutionarily dynamic gene families encoding odorant receptors (OR), trace amine-associated receptors (TAAR), V1Rs and V2Rs. A limited number of OR-like sequences have been found in invertebrate chordate genomes. Whether these gene families arose in basal or advanced vertebrates has not been resolved because these families have not been examined systematically in agnathan genomes.</p> <p>Results</p> <p><it>Petromyzon </it>is the only extant jawless vertebrate whose genome has been sequenced. Known to be exquisitely sensitive to several classes of odorants, lampreys detect fewer amino acids and steroids than teleosts. This reduced number of detectable odorants is indicative of reduced numbers of CR gene families or a reduced number of genes within CR families, or both, in the sea lamprey. In the lamprey genome we identified a repertoire of 59 intact single-exon CR genes, including 27 OR, 28 TAAR, and four V1R-like genes. These three CR families were expressed in the olfactory organ of both parasitic and adult life stages.</p> <p>Conclusion</p> <p>An extensive search in the lamprey genome failed to identify potential orthologs or pseudogenes of the multi-exon V2R family that is greatly expanded in teleost genomes, but did find intact calcium-sensing receptors (CASR) and intact metabotropic glutamate receptors (MGR). We conclude that OR and V1R arose in chordates after the cephalochordate-urochordate split, but before the diversification of jawed and jawless vertebrates. The advent and diversification of V2R genes from glutamate receptor-family G protein-coupled receptors, most likely the CASR, occurred after the agnathan-gnathostome divergence.</p

    Effect of aging on acute pancreatitis through gut microbiota

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    BackgroundCompared to younger people, older people have a higher risk and poorer prognosis of acute pancreatitis, but the effect of gut microbiota on acute pancreatitis is still unknown. We aim to investigate the effect of aging gut microbiota on acute pancreatitis and explore the potential mechanism of this phenomenon.MethodsEighteen fecal samples from healthy adult participants, including nine older and nine younger adults were collected. C57BL/6 mice were treated with antibiotics for fecal microbiota transplantation from older and younger participants. Acute pancreatitis was induced by cerulein and lipopolysaccharide in these mice. The effect of the aged gut microbiota was further tested via antibiotic treatment before or after acute pancreatitis induction.ResultsThe gut microbiota of older and younger adults differed greatly. Aged gut microbiota exacerbated acute pancreatitis during both the early and recovery stages. At the same time, the mRNA expression of multiple antimicrobial peptides in the pancreas and ileum declined in the older group. Antibiotic treatment before acute pancreatitis could remove the effect of aging gut microbiota, but antibiotic treatment after acute pancreatitis could not.ConclusionAging can affect acute pancreatitis through gut microbiota which characterizes the deletion of multiple types of non-dominant species. This change in gut microbiota may potentially regulate antimicrobial peptides in the early and recovery stages. The level of antimicrobial peptides has negative correlations with a more severe phenotype

    Glutamine in suppression of lipopolysaccharide-induced piglet intestinal inflammation: The crosstalk between AMPK activation and mitochondrial function

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    Publication history: Accepted - 18 March 2022; Published online - 26 March 2022.The study was conducted to investigate the regulatory mechanism of glutamine (Gln) on intestinal inflammation in an Escherichia coli lipopolysaccharide (E. coli LPS)-induced in vivo and in vitro models. Piglets (n = 8) weaned at 21 d of age were fed a basal diet (control and LPS groups) or 1% Gln diet (Gln + LPS group) ad libitum for 4 weeks. On d 22, 24, 26 and 28, piglets in the LPS and Gln + LPS groups were intraperitoneally injected with E. coli LPS. Intestinal porcine epithelial cells (IPEC-J2) (n = 6) induced by LPS were used to assess related mechanisms and compound C was used to inhibit adenosine 5â€Č-monophosphate-activated protein kinase (AMPK) activity. Our current results showed that compared with the LPS treatment, the Gln + LPS treatment had better growth performance and greater villus height (P < 0.05), and the Gln + LPS treatment reduced the rate of diarrhea by 6.4% (P < 0.05); the Gln + LPS treatment decreased serum tumor necrosis factor (TNF-ɑ), interleukin-6 (IL-6), K+, cortisol and insulin levels, whereas increased (P < 0.05) serum immunoglobulin M and epidermal growth factor levels; the Gln + LPS treatment increased (P < 0.05) the expression of aquaporins and AMPK pathway-associated targets in the jejunum and ileum of piglets, whereas decreased the expression of ion transporters (P < 0.05). The in vitro results showed that 4 mmol/L Gln administration could inhibit (P < 0.05) cell apoptosis and interleukin-1ÎČ (IL-1ÎČ), IL-6 and TNF-ɑ secretion in LPS-induced IPEC-J2 cells, promote (P < 0.05) mitochondrial respiratory metabolism and increase (P < 0.05) the number of mitochondria and mitochondrial membrane potential. The activity of AMPK was elevated by 70% to 300% in Gln-treated IPEC-J2 cells under LPS challenge or normal conditions. Our results indicate that pre-administration of Gln to piglets suppresses intestinal inflammation by modulating the crosstalk between AMPK activation and mitochondrial function.This work was supported by Huxiang Young Talent Support Program (2020RC3052), Natural Science Foundation of China (31902168, 31872371), Hunan Key Research and Development Plan (2020NK2059), State Key Laboratory of Animal Nutrition (2004DA125184F1907), Special Funds for Construction of Innovative Provinces in Hunan Province (2019RS3022), Guangxi Key Research and Development Plan (Guike AB19259012), and Guangxi Guilin Science and Technology Planning Project (2020010901)
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