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We use a 3-year panel from two poor provinces in Southern China to examine the nature of risks to which rural households are exposed and their ability to insure calorie consumption and spending of total consumption against idiosyncratic shocks to their income. We find that idiosyncratic risks are indeed the main source of income variation in the sample, consumption is better insured than total spending. Unlike total spending where full insurance is rejected in most cases, calorie intake is completely insured for both land-rich and land-poor households in both provinces. Access to even modest amounts of land significantly enhances households' ability to guard against total spending. Land-rich households are much better insured against total spending than land-poor households. The results are robust across model specifications although Generalized Method of Moments (GMM) estimations increase the magnitude of difference in total spending between the land-rich and the land-poor. Policies targeting poverty reduction and improving land use rights and land access to the poor could potentially improve the overall risk sharing ability of the rural poor.

Accurately forecasting the scope of coal mining subsidence area is of great significance to the protection of surface structures. Due to the peculiarities of the unconsolidated layers rock formation, the surface movement of the thick unconsolidated layers mining area converges slowly at the boundary of the basin, and the boundary of the subsidence basin is larger than under conventional conditions. It is found that the existing models have a poor prediction effect at the boundary, and the predicted subsidence basin range is smaller than the actual basin range. To solve this problem, a new surface deformation prediction model based on Boltzmann function (IB) is proposed in this paper. Aiming at the problem that the model function is highly nonlinear and difficult to obtain parameters, the multi-population genetic algorithm (MPGA) is introduced into the parameter solution of the prediction model, and the parameter calculation model based on multi-population genetic algorithm (MPGAIB) is constructed. The simulation experiment and engineering example analysis show that both the overall fitting effect and the fitting effect at the boundary of IB model are closer to the actual situation, The MPGAIB model has good ability to anti-random error and gross error, and the result is stable. INDEX TERMSmining subsidence, parameter calculation, Probability integral method, prediction model, thick unconsolidated layers List of abbreviations IB-Improved Boltzmann function MPGA-Multi-population genetic algorithm MPGAIB -Multi-population genetic algorithm parameter model PIM-Probability integral method SIE-Semi-infinitive Extraction FE-Finite Extraction FEAS-Finite extraction along strike FEAD-Finite extraction along dip NUM-The number of populations LNUM-The number of individuals in each population GGAP-The generation gap NVAR-The dimension of the variable Pc-The crossover probability Pm-The mutation probability MAXGEN -The optimal individual maintains the least algebra RMSE-Root Mean

On February 12, 2014, a large Mw7. 3 earthquake occurred in Yutian of Xijiang Province, China.We processed the global ionosphere maps provided by CODE (the Center for Orbit Determination in Europe ) and the foF2 (the critical frequency of F2-layer) data of Chongqing ionosonde station to analyze the preearthquake ionospheric anomalies. Solar activities and magnetic storm were checked by the sliding inter quartile range method to remove their effects on the ionosphere. A positive ionospheric anomaly with the large amplitude of 20 TECU was observed near the epicenter on February 3 ( lOth day before the earthquake). In addition, the foF2 at Chongqing station had an unusual increase of more than 40% on the day, which was consistent with the TEC (Total Electron Content) anomaly. The global disturbance represents that the peak of TEC anomaly didn't coincide with the vertical projection of epicenter. The TEC anomalous area was closer to the equator, and it mainly occurred from local time 16 : 00 to 20 : 00. An enhancement of TEC with the small amplitude also appeared in the magnetically conjugated region.