BACKGROUND:Amyotrophic lateral sclerosis (ALS) is the most common of all the motor neuron diseases and the absence of a biologic marker has made both diagnosis and tracking evolution of the disease difficult, Elect...BACKGROUND:Amyotrophic lateral sclerosis (ALS) is the most common of all the motor neuron diseases and the absence of a biologic marker has made both diagnosis and tracking evolution of the disease difficult, Electrodiagnostic tests play a fundamental role in quantifying pathological changes in the motor unit pool.OBJECTIVE:We assessed distal-proximal Motor Unit (MU) loss and changes using the method of motor unit number estimation (MUNE).DESIGN, TIME AND SETTING:A case-control study was performed at the Department of Neuroscience, Pisa University Medical School, Italy from December 1999 to November 2009. PARTICIPANTS:A total of 50 ALS patients were recruited, 30 males:mean age (59.6 ± 13.3) years; 20 females:mean age (63.9 ± 11.7) years; range (30-82) years; all patients had probable or definite ALS. Thirty healthy volunteers were recruited from department staffs, including 20 males and 10 females; mean age (57.7 ± 13.8) years served as controls.METHODS:MUNE was performed for both the biceps brachii and abductor digiti minimi muscles of the same side. The technique used relayed substantially on manual incremental stimulation of the motor nerve, known as the McComas technique (50 ms sweep duration, a gain of 2 mV/Div for M wave, 0.5 mV/Div for each step; filters 10-20 kHz).MAIN OUTCOME MEASURES:MUNE results were measured.RESULTS:Functioning MU numbers, measured by MUNE, decreased in the biceps brachii and abductor digiti minimi muscles over the entire one-year follow-up period (one assessment every three months) compared with baseline determination, the rate of MU decrease was similar in both muscles, but steeper distally.CONCLUSION:MUNE is a feasible method for ALS patients both proximally and distally to track changes over time in muscle MUs during the disease's evolution.展开更多
Saudi Arabian subtropical high pressure is a major system affecting general circulation of the atmosphere of west Asia. Its annual relocation affects the relocation of other systems in the area, such as Mediterranean ...Saudi Arabian subtropical high pressure is a major system affecting general circulation of the atmosphere of west Asia. Its annual relocation affects the relocation of other systems in the area, such as Mediterranean cyclones, Sudanese low pressure areas, and west wind waves. This system is known to relocate to the south and north in response to outward solar relocation, but the reasons behind its eastern and western relocation have not been studied thoroughly. The present study examined 1000 and 850 HPa levels over the course of 66 years (1948-2015) to determine a pattern of latitudinal and longitudinal relocation of the system using synoptic maps. The research showed that, after 2008, high pressure latitudinal and longitudinal swings were larger than in previous years and the annual high pressure relocation was not in concord with the apparent motion of the sun. At the onset of autumnal moderation, the high pressure core was positioned to the north of Saudi Arabia (22° - 30° north latitude and 42° - 50° south longitude). Southern movement continued until the end of March, when the core again relocated to the north. These relocations first occurred slowly, but the northern relocation occurred very quickly from May to June, such that the core moved northward 22° to 30°. After June, the core did not relocate much until the end of September. After September, it relocated strongly south in all time periods. It was noted that high pressure over Saudi Arabia had two cores from June to September in some years;in others the high pressure core was in southwestern Iran and Iraq. In still others, a southwest to northeast high pressure tab entered Iran from the southwest (Khuzestan) and continued northward with a core forming in the northern Caspian Sea.展开更多
To study the seismogeny process or the precursory behavior of the 1976 MS=7.0 Lijiang earthquake, we analyze the repeat gravity data with high precision from the Western Yunnan Earthquake Prediction Experiment Area (W...To study the seismogeny process or the precursory behavior of the 1976 MS=7.0 Lijiang earthquake, we analyze the repeat gravity data with high precision from the Western Yunnan Earthquake Prediction Experiment Area (WYEPEA) and the related results of geology and geophysics survey in this paper. Considering the gross errors caused by observation data and model difference, we have firstly inverted the slip distribution of the main active faults with time based on the robust Bayesian least squares estimation and multi-fault dislocation model. The re-sults show that the slip changes of the faults with time from 1990 to 1997 obviously reflect the preparation process of the Lijiang earthquake. The images of main precursor mode have the characteristic of main shock-after shock type, which is agreement to the model of coupling movement between crust density and crust deformation (DD mode of coupling movement).展开更多
The present work uses the Thermosphere Ionosphere Electrodynamics General Circulation Model(TIEGCM),under geomagnetically disturbed conditions that are closely related to the southward interplanetary magnetic field(IM...The present work uses the Thermosphere Ionosphere Electrodynamics General Circulation Model(TIEGCM),under geomagnetically disturbed conditions that are closely related to the southward interplanetary magnetic field(IMF),to investigate how the nighttime poleward wind(30°–50°magnetic latitude and 19–22 magnetic local time)responds to subauroral polarization streams(SAPS)that commence at different universal times(UTs).The SAPS effects on the poleward winds show a remarkable UT variation,with weaker magnitudes at 00 and 12 UT than at 06 and 18 UT.The strongest poleward wind emerges when SAPS commence at 06 UT,and the weakest poleward wind develops when SAPS occur at 00 UT.A diagnostic analysis of model results shows that the pressure gradient is more prominent for the developing of the poleward wind at 00 and 12 UT.Meanwhile,the effect of ion drag is important in the modulation of the poleward wind velocity at 06 and 18 UT.This is caused by the misalignment of the geomagnetic and geographic coordinate systems,resulting in a large component of ion drag in the geographically northward(southward)direction due to channel orientation of the SAPS at 06 and 18 UT(00 and 12 UT).The Coriolis force effect induced by westward winds maximizes(minimizes)when SAPS commence at 12 UT(00 UT).The centrifugal force due to the accelerated westward winds shows similar UT variations as the Coriolis force,but with an opposite effect.展开更多
Using a set of numerical experiments from 39 CMIP5 climate models, we project the emergence time for 4?C global warming with respect to pre-industrial levels and associated climate changes under the RCP8.5 greenhouse...Using a set of numerical experiments from 39 CMIP5 climate models, we project the emergence time for 4?C global warming with respect to pre-industrial levels and associated climate changes under the RCP8.5 greenhouse gas concentration scenario. Results show that, according to the 39 models, the median year in which 4?C global warming will occur is 2084.Based on the median results of models that project a 4?C global warming by 2100, land areas will generally exhibit stronger warming than the oceans annually and seasonally, and the strongest enhancement occurs in the Arctic, with the exception of the summer season. Change signals for temperature go outside its natural internal variabilities globally, and the signal-tonoise ratio averages 9.6 for the annual mean and ranges from 6.3 to 7.2 for the seasonal mean over the globe, with the greatest values appearing at low latitudes because of low noise. Decreased precipitation generally occurs in the subtropics, whilst increased precipitation mainly appears at high latitudes. The precipitation changes in most of the high latitudes are greater than the background variability, and the global mean signal-to-noise ratio is 0.5 and ranges from 0.2 to 0.4 for the annual and seasonal means, respectively. Attention should be paid to limiting global warming to 1.5?C, in which case temperature and precipitation will experience a far more moderate change than the natural internal variability. Large inter-model disagreement appears at high latitudes for temperature changes and at mid and low latitudes for precipitation changes. Overall, the intermodel consistency is better for temperature than for precipitation.展开更多
The main aim of soil monitoring system is to obtain the knowledge of the most current state and development of soil properties according to concrete threats to soil. To determine the significant changes of soil proper...The main aim of soil monitoring system is to obtain the knowledge of the most current state and development of soil properties according to concrete threats to soil. To determine the significant changes of soil properties in time, it is important to know spatial variability of concrete soil parameter for concrete site. Only those time changes of the soil parameter are significant, which exceed its spatial variability at the site. The main aim of the study has been focused on the evaluation of small-scale site heterogeneity of equilibrium soil bulk density and the integration of impact of this heterogeneity in evaluation of degradation process of soil compaction in time. As site variation coefficients have considerably varied at standard sampling with five repetitions during monitoring period, one-time detail spatial variability mapping of soil bulk density was realized at 17 repetitions on five selected monitoring sites with different soil type, texture and use. This increase in the number of sampling points helped us to specify and stabilize the values of variation coefficients (between minimum and maximum by standard sampling) as well as the extent of confidence intervals. Standard deviations at the chosen monitoring sites moved from 0.039 to 0.118 g·cm<sup><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"="">-</span>3</span></sup><span style="font-family:Verdana;"> in topsoil and from 0.031 to 0.067 g·cm</span><sup><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"="">-</span>3</span></sup><span style="font-family:Verdana;"> in subsoil and expressed as variation coefficient 2.9% - 9.2% and 2.0% - 4.9%, respectively. The intervals of significant time changes of soil bulk density for the sites and depths were determined on the base of its site confidence interval (95%) and uncertainty rate of its measure methodology. The time changes of bulk density values between single year-to-year sampling were overlapped by this interval of significant changes to obtain significant bulk density changes in time. This method allowed us to distinguish significant time changes in soil bulk density from insignificant ones. The bulk density value changes on the monitoring sites were significant in the range of six to nine years within observed period 2002-2014 in both depths.</span>展开更多
Based on the three-order Lagrangian equations, Hamilton's function of acceleration H^* and generalized acceleration momentum P^*α are defined, and pseudo-Hamilton canonical equations corresponding to three-order L...Based on the three-order Lagrangian equations, Hamilton's function of acceleration H^* and generalized acceleration momentum P^*α are defined, and pseudo-Hamilton canonical equations corresponding to three-order Lagrangian equations are obtained. The equations are similar to Hamilton's canonical equations of analytical mechanics in form.展开更多
A resurgent China contributes to the world. General Secretary Xi Jinping attaches great importance to the issues of the times and analyzes the development direction of humankind from the perspective and method of Marx...A resurgent China contributes to the world. General Secretary Xi Jinping attaches great importance to the issues of the times and analyzes the development direction of humankind from the perspective and method of Marxism. Further, he indicates that we must base ourselves on the overall strategy of the great rejuvenation of the Chinese nation and the significant changes occurring in the world that have not been seen in a century and makes a major judgment that the timing and international situation are favorable to China. Inevitably, Chinese now view themselves as equals of any other in the world, reflecting a historic change in the relations between China and the remaining world. In other words, no country can dictate terms to China. Building a powerful modern socialist country is a great goal set by the Communist Party of China(CPC). To build a great country and achieve a great cause, we must go through enormous struggle. Xi Jinping Thought on Diplomacy reflects on the issues of our times. Answering the questions and guiding the changes of our times, Xi Jinping Thought on Diplomacy is of great significance. Moreover, the CPC has remained true to socialism, and socialism has proved its worth to China.展开更多
Snow data collection systems in the western United States were originally designed to forecast water supply and may be subject to several sources of bias. In addition to climate change and weather modification effects...Snow data collection systems in the western United States were originally designed to forecast water supply and may be subject to several sources of bias. In addition to climate change and weather modification effects, site-specific effects may be introduced from vegetation changes, site physical changes, measurement technique, and sensor changes. This paper examines changes in Utah's snowpack conditions over the past decade compared with all previous measurement years, focusing on the 15 snow courses with the longest observational record within the state of Utah. Although patterns in snowpack data consistent with those that would be expected due to temperature h as greater declines at lower elevations and latitudes--were not identified, snow water equivalent decreased at sites with significant increases in vegetation coverage. Additionally, we provide a list of 22 snow courses in Utah that are best-suited for long-term climate analysis.展开更多
Based on the Gauss linear frequency modulated wavelet transform, a new characteristic index is presented, namely time frequency energy attenuation factor which can reflect the difference features of waveform in earthq...Based on the Gauss linear frequency modulated wavelet transform, a new characteristic index is presented, namely time frequency energy attenuation factor which can reflect the difference features of waveform in earthquake focus mechanism, wave traveling path and its attenuation characteristics in focal area or near field. In order to test its validity, we select the natural earthquakes and explosion or collapse events whose focus mechanisms vary obviously,and some natural earthquakes located at the same site or in a very small area. The study indicates that the time frequency energy attenuation factors of the natural earthquakes are obviously different with that of explosion or collapse events, and the change of the time frequency energy attenuation factors is relatively stable for the earthquakes under the normal seismicity background. Using the above mentioned method, it is expected to offer a useful criterion for strong earthquake prediction by continuous earthquake observation.展开更多
Based on a synthetic geological study of drilling, well logging and core observations, two main genetic types of Chang 9sand body in Odors Basin were recognized, which included two effects, that is, delta environment ...Based on a synthetic geological study of drilling, well logging and core observations, two main genetic types of Chang 9sand body in Odors Basin were recognized, which included two effects, that is, delta environment and tractive current effects that lead to the development of mouth bar, distal bar, sheet sand and other sand bodies of subaerial and subaqueous distributary channel,natural levee, flood fan and delta front, and shore-shallow lake environment and lake flow transformation effects that result in the development of sandy beach bar, sheet sand and other sand bodies. Chang 9 sand body mainly developed five basic vertical structures, namely box shape, campaniform, infundibuliform, finger and dentoid. The vertical stacking patterns of multilayer sand body was complex, and the common shapes included box shape + box shape, campaniform + campaniform, campaniform + box shape, infundibuliform + infundibuliform, campaniform + infundibuliform, box shape + campaniform, box shape + infundibuliform,and finger + finger. Based on the analysis on major dominating factors of vertical structure of sand body, sedimentary environment,sedimentary facies and rise, fall and cycle of base level are identified as the major geological factors that control the vertical structure of single sand body as well as vertical stacking patterns and distribution of multistory sand bodies.展开更多
Currently, most visual servoing system must be calibrated, while it is impossible to calibrate cameras and robot models precisely in industrial practice, so a novel dynamic uncalibrated eye-in-hand visual servoing sys...Currently, most visual servoing system must be calibrated, while it is impossible to calibrate cameras and robot models precisely in industrial practice, so a novel dynamic uncalibrated eye-in-hand visual servoing system of tracking a moving target is proposed. The method does not require calibration of camera and robot kinematic models. Vision guided algorithm for tracking dynamic image is developed through minimizing nonlinear objective function. For the large residual has not been approximated in dynamic environment and the change of composite image Jacobian with time increment has not been computed in visual servoing system now,large residuals are dynamic approximated and the change of composite image Jacobian at each iterative step is computed. Simulation results demonstrate the validity of these approaches.展开更多
From November 28 to December 9,the 17th Conference of the Parties(COP17) to the United Nations Framework Convention on Climate Change takes place in Durban,South Africa.Discussions will center on what the internationa...From November 28 to December 9,the 17th Conference of the Parties(COP17) to the United Nations Framework Convention on Climate Change takes place in Durban,South Africa.Discussions will center on what the international community can do to cope with the increasingly serious climate change.In an article for China Today,Xie Zhenhua, Vice Chairman of National Development and Reform Commission,explained China’s efforts in carbon emission reduction and its stance at the upcoming conference.His edited views follow:展开更多
Based on TIMESAT 3.2 platform, MODIS NDVI data(2000–2015) of Qaidam Basin are fitted, and three main phenological parameters are extracted with the method of dynamic threshold, including the start of growth season(SG...Based on TIMESAT 3.2 platform, MODIS NDVI data(2000–2015) of Qaidam Basin are fitted, and three main phenological parameters are extracted with the method of dynamic threshold, including the start of growth season(SGS), the end of growth season(EGS) and the length of growth season(LGS). The spatial and temporal variation of vegetation phenology and its response to climate changes are analyzed respectively. The conclusions are as follows:(1) SGS is mainly delayed as a whole. Areas delayed are more than the advanced in EGS, and EGS is a little delayed as a whole. LGS is generally shortened.(2) With the altitude rising, SGS is delayed, EGS is advanced, and LGS is shortened and phenophase appears a big variation below 3000 m and above 5000 m.(3) From 2000 to 2015, the temperature appears a slight increase along with a big fluctuation, and the precipitation increases evidently.(4) Response of phenophase to precipitation is not obvious in the low elevation humid regions, where SGS arrives early and EGS delays; while, in the upper part of the mountain regions, SGS delays and EGS advances with temperature rising, SGS arrives early and EGS delays with precipitation increasing.展开更多
爱美之心,人皆有之,但研究人员发现:Individual and social attitudes to-ward what’s acceptable,and what’s beautiful,change over time,因此尽管有Survival of the Prettiest(靓者生存)的说法,在目前轰轰烈烈的“人造”美女与帅...爱美之心,人皆有之,但研究人员发现:Individual and social attitudes to-ward what’s acceptable,and what’s beautiful,change over time,因此尽管有Survival of the Prettiest(靓者生存)的说法,在目前轰轰烈烈的“人造”美女与帅哥的潮流中,是否选择plastic-surgery(整形手术)最好还是三思而行。展开更多
We survey some recent progress in the study of stability of elliptic Harnack inequalities under form-bounded perturbations for strongly local Dirichlet forms on complete locally compact separable metric spaces.
In this paper,we propose a novel model for pricing double barrier options,where the asset price is modeled as a threshold geometric Brownian motion time changed by an integrated activity rate process,which is driven b...In this paper,we propose a novel model for pricing double barrier options,where the asset price is modeled as a threshold geometric Brownian motion time changed by an integrated activity rate process,which is driven by the convolution of a fractional kernel with the CIR process.The new model both captures the leverage effect and produces rough paths for the volatility process.The model also nests the threshold diffusion,Heston and rough Heston models.We can derive analytical formulas for the double barrier option prices based on the eigenfunction expansion method.We also implement the model and numerically investigate the sensitivities of option prices with respect to the parameters of the model.展开更多
Large areas in the Czech Republic were used for open casts of brown coal mining.Many of them have been already closed.Reclamation of them and of their dumps is the next step intheir development.It is possible to divid...Large areas in the Czech Republic were used for open casts of brown coal mining.Many of them have been already closed.Reclamation of them and of their dumps is the next step intheir development.It is possible to divide used reclamations into the forest,hydrologic,agricultural and other onesroads,etc.Their age varies from 45 years to as yet unfinished.Reclaimed areas are documented in reclamation projects.Information about age and land use determined groups of these areas to be evaluated by vegetation indices.100 areas with forest type were evaluated.Eight vegetation indices(NDVI,DVI,RVI,PVI,SAVI,MSAVI,TSAVI and EVI)were calculated and their average value in each area in 1988,1992 and 1998 Thematic Mapper data were compared.Changes over years showed close relation to precipitations of previous periods.This relation was confirmed by evaluation of forest areas situated near reclamation areas.Positive/negative changes of vegetation indices were different for different groups and different vegetation indices.An overview of results of vegetation indices is presented for individual areas whose land use comprised at least partly forest stand.Results in a 4-year period(19881992)were in many areas by many indices negative,changes in 10 years were in most areas by most vegetation indices positive.Changes,minimum values and maximum values in groups were compared.Evaluation of vegetation indices brought again various results.One vegetation index is not sufficient to prove improvement/deterioration of vegetation changes.Precipitation state before measurement should be controlled.Temporary shortage of precipitation can cause vegetation cover deterioration,which is also only temporary.The best development derived from vegetation indices evaluation was found at forest reclamation with mixed tree stand that was 1020 years old.The method was derived as a tool for post-finishing control of vegetation development of reclamations performed in several year periods.展开更多
In present work studied the new boundary value problem for semi linear(Power-type nonlinearities)system equations of mixed hyperbolic-elliptic Keldysh type in the multivariate dimension with the changing time directio...In present work studied the new boundary value problem for semi linear(Power-type nonlinearities)system equations of mixed hyperbolic-elliptic Keldysh type in the multivariate dimension with the changing time direction.Considered problem and equation belongs to the modern level partial differential equations.Applying methods of functional analysis,topological methods,“ε”-regularizing.and continuation by the parameter at the same time with aid of a prior estimates,under assumptions conditions on coefficients of equations of system,the existence and uniqueness of generalized and regular solutions of a boundary problem are established in a weighted Sobolev's space.In this work one of main idea consists of show that the new boundary value problem which investigated in case of linear system equations can be well-posed when added nonlinear terms to this linear system equations,moreover in this case constructed new weithged spaces,the identity between of strong and weak solutions is established.展开更多
In this paper, we shall study how energy functionals and Revuz measures change under time change of Markov processes and provide an intuitive and direct approach to the computation of the Levy system and jumping measu...In this paper, we shall study how energy functionals and Revuz measures change under time change of Markov processes and provide an intuitive and direct approach to the computation of the Levy system and jumping measure of time changed process.展开更多
基金Supported by the Italian MIUR PRIN Grant year 2006,# 2006062332_002
文摘BACKGROUND:Amyotrophic lateral sclerosis (ALS) is the most common of all the motor neuron diseases and the absence of a biologic marker has made both diagnosis and tracking evolution of the disease difficult, Electrodiagnostic tests play a fundamental role in quantifying pathological changes in the motor unit pool.OBJECTIVE:We assessed distal-proximal Motor Unit (MU) loss and changes using the method of motor unit number estimation (MUNE).DESIGN, TIME AND SETTING:A case-control study was performed at the Department of Neuroscience, Pisa University Medical School, Italy from December 1999 to November 2009. PARTICIPANTS:A total of 50 ALS patients were recruited, 30 males:mean age (59.6 ± 13.3) years; 20 females:mean age (63.9 ± 11.7) years; range (30-82) years; all patients had probable or definite ALS. Thirty healthy volunteers were recruited from department staffs, including 20 males and 10 females; mean age (57.7 ± 13.8) years served as controls.METHODS:MUNE was performed for both the biceps brachii and abductor digiti minimi muscles of the same side. The technique used relayed substantially on manual incremental stimulation of the motor nerve, known as the McComas technique (50 ms sweep duration, a gain of 2 mV/Div for M wave, 0.5 mV/Div for each step; filters 10-20 kHz).MAIN OUTCOME MEASURES:MUNE results were measured.RESULTS:Functioning MU numbers, measured by MUNE, decreased in the biceps brachii and abductor digiti minimi muscles over the entire one-year follow-up period (one assessment every three months) compared with baseline determination, the rate of MU decrease was similar in both muscles, but steeper distally.CONCLUSION:MUNE is a feasible method for ALS patients both proximally and distally to track changes over time in muscle MUs during the disease's evolution.
文摘Saudi Arabian subtropical high pressure is a major system affecting general circulation of the atmosphere of west Asia. Its annual relocation affects the relocation of other systems in the area, such as Mediterranean cyclones, Sudanese low pressure areas, and west wind waves. This system is known to relocate to the south and north in response to outward solar relocation, but the reasons behind its eastern and western relocation have not been studied thoroughly. The present study examined 1000 and 850 HPa levels over the course of 66 years (1948-2015) to determine a pattern of latitudinal and longitudinal relocation of the system using synoptic maps. The research showed that, after 2008, high pressure latitudinal and longitudinal swings were larger than in previous years and the annual high pressure relocation was not in concord with the apparent motion of the sun. At the onset of autumnal moderation, the high pressure core was positioned to the north of Saudi Arabia (22° - 30° north latitude and 42° - 50° south longitude). Southern movement continued until the end of March, when the core again relocated to the north. These relocations first occurred slowly, but the northern relocation occurred very quickly from May to June, such that the core moved northward 22° to 30°. After June, the core did not relocate much until the end of September. After September, it relocated strongly south in all time periods. It was noted that high pressure over Saudi Arabia had two cores from June to September in some years;in others the high pressure core was in southwestern Iran and Iraq. In still others, a southwest to northeast high pressure tab entered Iran from the southwest (Khuzestan) and continued northward with a core forming in the northern Caspian Sea.
基金Joint Seismological Science Foundation of China (101005) and the State Key Basic Research Project (G1998040703).
文摘To study the seismogeny process or the precursory behavior of the 1976 MS=7.0 Lijiang earthquake, we analyze the repeat gravity data with high precision from the Western Yunnan Earthquake Prediction Experiment Area (WYEPEA) and the related results of geology and geophysics survey in this paper. Considering the gross errors caused by observation data and model difference, we have firstly inverted the slip distribution of the main active faults with time based on the robust Bayesian least squares estimation and multi-fault dislocation model. The re-sults show that the slip changes of the faults with time from 1990 to 1997 obviously reflect the preparation process of the Lijiang earthquake. The images of main precursor mode have the characteristic of main shock-after shock type, which is agreement to the model of coupling movement between crust density and crust deformation (DD mode of coupling movement).
基金the National Science Foundation.The work is supported by the National Nature Science Foundation of China(No.s 41974182,41674153,41521063,41431073,41521062 and 42004135)the US NSF award AGS-1762141 and the US AFOSR MURI award FA9559-16-1-0364+1 种基金the NSF grant AGS-1452309The Spark Project at Wuhan University(2042020gf0024)also sponsors this work.
文摘The present work uses the Thermosphere Ionosphere Electrodynamics General Circulation Model(TIEGCM),under geomagnetically disturbed conditions that are closely related to the southward interplanetary magnetic field(IMF),to investigate how the nighttime poleward wind(30°–50°magnetic latitude and 19–22 magnetic local time)responds to subauroral polarization streams(SAPS)that commence at different universal times(UTs).The SAPS effects on the poleward winds show a remarkable UT variation,with weaker magnitudes at 00 and 12 UT than at 06 and 18 UT.The strongest poleward wind emerges when SAPS commence at 06 UT,and the weakest poleward wind develops when SAPS occur at 00 UT.A diagnostic analysis of model results shows that the pressure gradient is more prominent for the developing of the poleward wind at 00 and 12 UT.Meanwhile,the effect of ion drag is important in the modulation of the poleward wind velocity at 06 and 18 UT.This is caused by the misalignment of the geomagnetic and geographic coordinate systems,resulting in a large component of ion drag in the geographically northward(southward)direction due to channel orientation of the SAPS at 06 and 18 UT(00 and 12 UT).The Coriolis force effect induced by westward winds maximizes(minimizes)when SAPS commence at 12 UT(00 UT).The centrifugal force due to the accelerated westward winds shows similar UT variations as the Coriolis force,but with an opposite effect.
基金supported by the National Basic Research Program of China (Grant No. 2016YFA0602401)the National Natural Science Foundation of China (Grant No. 41421004)
文摘Using a set of numerical experiments from 39 CMIP5 climate models, we project the emergence time for 4?C global warming with respect to pre-industrial levels and associated climate changes under the RCP8.5 greenhouse gas concentration scenario. Results show that, according to the 39 models, the median year in which 4?C global warming will occur is 2084.Based on the median results of models that project a 4?C global warming by 2100, land areas will generally exhibit stronger warming than the oceans annually and seasonally, and the strongest enhancement occurs in the Arctic, with the exception of the summer season. Change signals for temperature go outside its natural internal variabilities globally, and the signal-tonoise ratio averages 9.6 for the annual mean and ranges from 6.3 to 7.2 for the seasonal mean over the globe, with the greatest values appearing at low latitudes because of low noise. Decreased precipitation generally occurs in the subtropics, whilst increased precipitation mainly appears at high latitudes. The precipitation changes in most of the high latitudes are greater than the background variability, and the global mean signal-to-noise ratio is 0.5 and ranges from 0.2 to 0.4 for the annual and seasonal means, respectively. Attention should be paid to limiting global warming to 1.5?C, in which case temperature and precipitation will experience a far more moderate change than the natural internal variability. Large inter-model disagreement appears at high latitudes for temperature changes and at mid and low latitudes for precipitation changes. Overall, the intermodel consistency is better for temperature than for precipitation.
文摘The main aim of soil monitoring system is to obtain the knowledge of the most current state and development of soil properties according to concrete threats to soil. To determine the significant changes of soil properties in time, it is important to know spatial variability of concrete soil parameter for concrete site. Only those time changes of the soil parameter are significant, which exceed its spatial variability at the site. The main aim of the study has been focused on the evaluation of small-scale site heterogeneity of equilibrium soil bulk density and the integration of impact of this heterogeneity in evaluation of degradation process of soil compaction in time. As site variation coefficients have considerably varied at standard sampling with five repetitions during monitoring period, one-time detail spatial variability mapping of soil bulk density was realized at 17 repetitions on five selected monitoring sites with different soil type, texture and use. This increase in the number of sampling points helped us to specify and stabilize the values of variation coefficients (between minimum and maximum by standard sampling) as well as the extent of confidence intervals. Standard deviations at the chosen monitoring sites moved from 0.039 to 0.118 g·cm<sup><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"="">-</span>3</span></sup><span style="font-family:Verdana;"> in topsoil and from 0.031 to 0.067 g·cm</span><sup><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"="">-</span>3</span></sup><span style="font-family:Verdana;"> in subsoil and expressed as variation coefficient 2.9% - 9.2% and 2.0% - 4.9%, respectively. The intervals of significant time changes of soil bulk density for the sites and depths were determined on the base of its site confidence interval (95%) and uncertainty rate of its measure methodology. The time changes of bulk density values between single year-to-year sampling were overlapped by this interval of significant changes to obtain significant bulk density changes in time. This method allowed us to distinguish significant time changes in soil bulk density from insignificant ones. The bulk density value changes on the monitoring sites were significant in the range of six to nine years within observed period 2002-2014 in both depths.</span>
文摘Based on the three-order Lagrangian equations, Hamilton's function of acceleration H^* and generalized acceleration momentum P^*α are defined, and pseudo-Hamilton canonical equations corresponding to three-order Lagrangian equations are obtained. The equations are similar to Hamilton's canonical equations of analytical mechanics in form.
文摘A resurgent China contributes to the world. General Secretary Xi Jinping attaches great importance to the issues of the times and analyzes the development direction of humankind from the perspective and method of Marxism. Further, he indicates that we must base ourselves on the overall strategy of the great rejuvenation of the Chinese nation and the significant changes occurring in the world that have not been seen in a century and makes a major judgment that the timing and international situation are favorable to China. Inevitably, Chinese now view themselves as equals of any other in the world, reflecting a historic change in the relations between China and the remaining world. In other words, no country can dictate terms to China. Building a powerful modern socialist country is a great goal set by the Communist Party of China(CPC). To build a great country and achieve a great cause, we must go through enormous struggle. Xi Jinping Thought on Diplomacy reflects on the issues of our times. Answering the questions and guiding the changes of our times, Xi Jinping Thought on Diplomacy is of great significance. Moreover, the CPC has remained true to socialism, and socialism has proved its worth to China.
文摘Snow data collection systems in the western United States were originally designed to forecast water supply and may be subject to several sources of bias. In addition to climate change and weather modification effects, site-specific effects may be introduced from vegetation changes, site physical changes, measurement technique, and sensor changes. This paper examines changes in Utah's snowpack conditions over the past decade compared with all previous measurement years, focusing on the 15 snow courses with the longest observational record within the state of Utah. Although patterns in snowpack data consistent with those that would be expected due to temperature h as greater declines at lower elevations and latitudes--were not identified, snow water equivalent decreased at sites with significant increases in vegetation coverage. Additionally, we provide a list of 22 snow courses in Utah that are best-suited for long-term climate analysis.
文摘Based on the Gauss linear frequency modulated wavelet transform, a new characteristic index is presented, namely time frequency energy attenuation factor which can reflect the difference features of waveform in earthquake focus mechanism, wave traveling path and its attenuation characteristics in focal area or near field. In order to test its validity, we select the natural earthquakes and explosion or collapse events whose focus mechanisms vary obviously,and some natural earthquakes located at the same site or in a very small area. The study indicates that the time frequency energy attenuation factors of the natural earthquakes are obviously different with that of explosion or collapse events, and the change of the time frequency energy attenuation factors is relatively stable for the earthquakes under the normal seismicity background. Using the above mentioned method, it is expected to offer a useful criterion for strong earthquake prediction by continuous earthquake observation.
基金Project(2011D-5006-0105)supported by the Technology Innovation Foundation of CNPC,ChinaProject(SZD0414)supported by the Key Discipline of Mineral Prospecting and Exploration of Sichuan Province,China
文摘Based on a synthetic geological study of drilling, well logging and core observations, two main genetic types of Chang 9sand body in Odors Basin were recognized, which included two effects, that is, delta environment and tractive current effects that lead to the development of mouth bar, distal bar, sheet sand and other sand bodies of subaerial and subaqueous distributary channel,natural levee, flood fan and delta front, and shore-shallow lake environment and lake flow transformation effects that result in the development of sandy beach bar, sheet sand and other sand bodies. Chang 9 sand body mainly developed five basic vertical structures, namely box shape, campaniform, infundibuliform, finger and dentoid. The vertical stacking patterns of multilayer sand body was complex, and the common shapes included box shape + box shape, campaniform + campaniform, campaniform + box shape, infundibuliform + infundibuliform, campaniform + infundibuliform, box shape + campaniform, box shape + infundibuliform,and finger + finger. Based on the analysis on major dominating factors of vertical structure of sand body, sedimentary environment,sedimentary facies and rise, fall and cycle of base level are identified as the major geological factors that control the vertical structure of single sand body as well as vertical stacking patterns and distribution of multistory sand bodies.
文摘Currently, most visual servoing system must be calibrated, while it is impossible to calibrate cameras and robot models precisely in industrial practice, so a novel dynamic uncalibrated eye-in-hand visual servoing system of tracking a moving target is proposed. The method does not require calibration of camera and robot kinematic models. Vision guided algorithm for tracking dynamic image is developed through minimizing nonlinear objective function. For the large residual has not been approximated in dynamic environment and the change of composite image Jacobian with time increment has not been computed in visual servoing system now,large residuals are dynamic approximated and the change of composite image Jacobian at each iterative step is computed. Simulation results demonstrate the validity of these approaches.
文摘From November 28 to December 9,the 17th Conference of the Parties(COP17) to the United Nations Framework Convention on Climate Change takes place in Durban,South Africa.Discussions will center on what the international community can do to cope with the increasingly serious climate change.In an article for China Today,Xie Zhenhua, Vice Chairman of National Development and Reform Commission,explained China’s efforts in carbon emission reduction and its stance at the upcoming conference.His edited views follow:
基金National Natural Science Foundation of China,No.40971118Physical Geography Key Disciplines Construction Subjects of Hebei Province
文摘Based on TIMESAT 3.2 platform, MODIS NDVI data(2000–2015) of Qaidam Basin are fitted, and three main phenological parameters are extracted with the method of dynamic threshold, including the start of growth season(SGS), the end of growth season(EGS) and the length of growth season(LGS). The spatial and temporal variation of vegetation phenology and its response to climate changes are analyzed respectively. The conclusions are as follows:(1) SGS is mainly delayed as a whole. Areas delayed are more than the advanced in EGS, and EGS is a little delayed as a whole. LGS is generally shortened.(2) With the altitude rising, SGS is delayed, EGS is advanced, and LGS is shortened and phenophase appears a big variation below 3000 m and above 5000 m.(3) From 2000 to 2015, the temperature appears a slight increase along with a big fluctuation, and the precipitation increases evidently.(4) Response of phenophase to precipitation is not obvious in the low elevation humid regions, where SGS arrives early and EGS delays; while, in the upper part of the mountain regions, SGS delays and EGS advances with temperature rising, SGS arrives early and EGS delays with precipitation increasing.
文摘爱美之心,人皆有之,但研究人员发现:Individual and social attitudes to-ward what’s acceptable,and what’s beautiful,change over time,因此尽管有Survival of the Prettiest(靓者生存)的说法,在目前轰轰烈烈的“人造”美女与帅哥的潮流中,是否选择plastic-surgery(整形手术)最好还是三思而行。
文摘We survey some recent progress in the study of stability of elliptic Harnack inequalities under form-bounded perturbations for strongly local Dirichlet forms on complete locally compact separable metric spaces.
文摘In this paper,we propose a novel model for pricing double barrier options,where the asset price is modeled as a threshold geometric Brownian motion time changed by an integrated activity rate process,which is driven by the convolution of a fractional kernel with the CIR process.The new model both captures the leverage effect and produces rough paths for the volatility process.The model also nests the threshold diffusion,Heston and rough Heston models.We can derive analytical formulas for the double barrier option prices based on the eigenfunction expansion method.We also implement the model and numerically investigate the sensitivities of option prices with respect to the parameters of the model.
基金The project was financially supported by grant of the Czech Grant Agency GA 205/06/1037 Application of Geoinformation Technologies for Improvement of Rainfall-Runoff Relation-ships.
文摘Large areas in the Czech Republic were used for open casts of brown coal mining.Many of them have been already closed.Reclamation of them and of their dumps is the next step intheir development.It is possible to divide used reclamations into the forest,hydrologic,agricultural and other onesroads,etc.Their age varies from 45 years to as yet unfinished.Reclaimed areas are documented in reclamation projects.Information about age and land use determined groups of these areas to be evaluated by vegetation indices.100 areas with forest type were evaluated.Eight vegetation indices(NDVI,DVI,RVI,PVI,SAVI,MSAVI,TSAVI and EVI)were calculated and their average value in each area in 1988,1992 and 1998 Thematic Mapper data were compared.Changes over years showed close relation to precipitations of previous periods.This relation was confirmed by evaluation of forest areas situated near reclamation areas.Positive/negative changes of vegetation indices were different for different groups and different vegetation indices.An overview of results of vegetation indices is presented for individual areas whose land use comprised at least partly forest stand.Results in a 4-year period(19881992)were in many areas by many indices negative,changes in 10 years were in most areas by most vegetation indices positive.Changes,minimum values and maximum values in groups were compared.Evaluation of vegetation indices brought again various results.One vegetation index is not sufficient to prove improvement/deterioration of vegetation changes.Precipitation state before measurement should be controlled.Temporary shortage of precipitation can cause vegetation cover deterioration,which is also only temporary.The best development derived from vegetation indices evaluation was found at forest reclamation with mixed tree stand that was 1020 years old.The method was derived as a tool for post-finishing control of vegetation development of reclamations performed in several year periods.
文摘In present work studied the new boundary value problem for semi linear(Power-type nonlinearities)system equations of mixed hyperbolic-elliptic Keldysh type in the multivariate dimension with the changing time direction.Considered problem and equation belongs to the modern level partial differential equations.Applying methods of functional analysis,topological methods,“ε”-regularizing.and continuation by the parameter at the same time with aid of a prior estimates,under assumptions conditions on coefficients of equations of system,the existence and uniqueness of generalized and regular solutions of a boundary problem are established in a weighted Sobolev's space.In this work one of main idea consists of show that the new boundary value problem which investigated in case of linear system equations can be well-posed when added nonlinear terms to this linear system equations,moreover in this case constructed new weithged spaces,the identity between of strong and weak solutions is established.
基金the National Natural Science Foundation of China (Grant No. 10771131)the National Basic Research Program of China (973 Program) (Grant No. 2007CB814904)
文摘In this paper, we shall study how energy functionals and Revuz measures change under time change of Markov processes and provide an intuitive and direct approach to the computation of the Levy system and jumping measure of time changed process.