A path analysis of the cultivated land change in Hubei Province,China

Hubei Province is one of the critical grain production regions in China with the quantitative cultivated landand good natural condition; it plays an important role in grain security in China. However, owing to rapid economicgrowth, population pressures, anthropogenic activities, and natural disasters, the quality of the cultivated land hassignificantly decreased in recent years and environmental resources are under increasing stress. In order to research onthe mechanism of the change of the cultivated land, this paper analyzes qualitatively the influencing factors of thecultivated land change in Hubei Province from 1978 to 2004, and distinguishes the direct factors from indirect influentones by means of the approach of the path analysis. The result shows that the area of the rent land in the total non-agricultural land, the total population growth and the fixed asset investment are the main factors deciding the change ofthe cultivated land. Meanwhile, the density of the transportation network, the proportion of per capita income of ruralcitizens to that of urban citizens, non-agricultural gross domestic production’s share of the total GDP has a less directeffect but a more indirect influence on the decrease of the cultivated land in Hubei Province. The result means that whilesome factors have less direct influence on the change of the cultivated land, its indirect influence are significant, viceversa. Thus it’s necessary to adopt a comprehensive measurement to protect the cultivated land.

RECENT DEVELOPMENT OF RESEARCH ON ENVIRONMENTAL EVOLUTION IN CHINA

Recent achievements of the research on Chinese environmental evolution are brieny summarized in this paper. Following aspects are touched upon: relationship between Chinese environmental evolution and global change, the influence of the swift uplift of the Qinghai-Xizang Plateau, time sequence and the reconstruction of environment in characteristic stages, trend towards dryness in north and northwestern China, sea level change and regional studies.

Enhancement of proton collimation and acceleration by an ultra-intense laser interacting with a cone target followed by a beam collimator

A special method is proposed of a laser-induced cavity pressure acceleration scheme for collimating,accelerating and guiding protons,using a single-cone target with a beam collimator through a target normal sheath acceleration mechanism.In addition,the problems involved are studied by using two-dimensional particle-in-cell simulations.The results show that the proton beam can be collimated,accelerated and guided effectively through this type of target.Theoretically,a formula is derived for the combined electric field of accelerating protons.Compared with a proton beam without a beam collimator,the proton beam density and cut-off energy of protons in the type II are increased by 3.3 times and 10%respectively.Detailed analysis shows that the enhancement is mainly due to the compact and strong sheath electrostatic field,and that the beam collimator plays a role in focusing energy.In addition,the simulation results show that the divergence angle of the proton beam in type II is less than 1.67 times that of type I.The more prominent point is that the proton number of type II is 2.2 times higher than that of type I.This kind of target has important applications in many fields,such as fast ion ignition in inertial fusion,high energy physics and proton therapy.

Hawking effect of Dirac particles in non-stationary Kerr space-time

In the process of dealing with the Hawking effect of Dirac particles in the non-stationary Kerr space-time, a new universal method to define the generalized Tortoise coordinate transformation is given. By means of this coordinate transformation, one can discuss the properties of the dynamical equation of particles near event horizons, and get automatically the temperature of Hawking radiation using the method suggested by Damour and others, and thereby dodge the difficulties in calculating the renormalised energy-momentum tensor.

Reconsidering the efficiency of grazing exclusion using fences on the Tibetan Plateau

Grazing exclusion using fences is a key policy being applied by the Chinese government to rehabilitate degraded grasslands on the Tibetan Plateau(TP)and elsewhere.However,there is a limited understanding of the effects of grazing exclusion on alpine ecosystem functions and services and its impacts on herders’livelihoods.Our meta-analyses and questionnaire-based surveys revealed that grazing exclusion with fences was effective in promoting aboveground vegetation growth for up to four years in degraded alpine meadows and for up to eight years in the alpine steppes of the TP.Longer-term fencing did not bring any ecological and economic benefits.We also found that fencing hindered wildlife movement,increased grazing pressure in unfenced areas,lowered the satisfaction of herders,and rendered substantial financial costs to both regional and national governments.We recommend that traditional free grazing should be encouraged if applicable,short-term fencing(for 4-8 years)should be adopted in severely degraded grasslands,and fencing should be avoided in key wildlife habitat areas,especially the protected large mammal species.

A Global Analysis of the Relationship Between Urbanization and Fatalities in Earthquake-Prone Areas

Urbanization can be a challenge and an opportunity for earthquake risk mitigation.However,little is known about the changes in exposure(for example,population and urban land)to earthquakes in the context of global urbanization,and their impacts on fatalities in earthquake-prone areas.We present a global analysis of the changes in population size and urban land area in earthquake-prone areas from 1990 to 2015,and their impacts on earthquake-related fatalities.We found that more than two thirds of population growth(or 70%of total population in 2015)and nearly three quarters of earthquake-related deaths(or 307,918 deaths)in global earthquake-prone areas occurred in developing countries with an urbanization ratio(percentage of urban population to total population)between 20 and 60%.Holding other factors constant,population size was significantly and positively associated with earthquake fatalities,while the area of urban land was negatively related.The results suggest that fatalities increase for areas where the urbanization ratio is low,but after a ratio between 40 and 50%occurs,earthquake fatalities decline.This finding suggests that the resistance of building and infrastructure is greater in countries with higher urbanization ratios and highlights the need for further investigation.Our quantitative analysis is extended into the future using Shared Socioeconomic Pathways to reveal that by 2050,more than 50%of the population increase in global earthquake-prone areas will take place in a few developing countries(Pakistan,India,Afghanistan,and Bangladesh)that are particularly vulnerable to earthquakes.To reduce earthquake-induced fatalities,enhanced resilience of buildings and urban infrastructure generally in these few countries should be a priority.

Theoretical Study on Photodecarboxylation Reaction of Acrylic Acid in Gas Phase

1 Introduction Nowadays. theoretical studies on mechanism of reaction at electronic excited state are mainly about the small molecules, among which formaldehyde has been the subject of numerous investigations. This is due to the fact that the mechanisms of photochemical reactions are rather complex and for reaction pathway at excited state, optimization

New characterizations of Musielak-Orlicz-Sobolev spaces via sharp ball averaging functions

We establish a new characterization of the Musielak-Orlicz-Sobolev space on ?n, which includes the classical Orlicz-Sobolev space, the weighted Sobolev space, and the variable exponent Sobolev space as special cases, in terms of sharp ball averaging functions. Even in a special case, namely, the variable exponent Sobolev space, the obtained result in this article improves the corresponding result obtained by P. H?st? and A. M. Ribeiro [Commun. Contemp. Math., 2017, 19: 1650022] via weakening the assumption f ∈ L^1(R^n) into f ∈ L^1loc(R^n), which was conjectured to be true by Hosto and Ribeiro in the aforementioned same article.

The properties of high-pressure treated Eu-iodides

As is known, the compounds containing Eu2+ ions under ambient pressure are sosensitive to moisture and oxygen that they cause great diffculty in sample handling andmeasurement. In order to improve the Eu2+ stability to a certain extent, we report in thisletter the stability, structure and fluorescence properties of EuI2,RbEuI3,RbEu2I5 andRb3Eul5 compounds under 20 kbar pressure.