Fractional differential constitutive relationships are introduced to depict the history of dynamic stress inten- sity factors （DSIFs） for a semi-infinite crack in infinite viscoelastic material subjected to anti-pla...Fractional differential constitutive relationships are introduced to depict the history of dynamic stress inten- sity factors （DSIFs） for a semi-infinite crack in infinite viscoelastic material subjected to anti-plane shear impact load. The basic equations which govern the anti-plane deformation behavior are converted to a fractional wave-like equation. By utilizing Laplace and Fourier integral transforms, the fractional wave-like equation is cast into an ordinary differential equation （ODE）. The unknown function in the solution of ODE is obtained by applying Fourier transform directly to the boundary conditions of fractional wave-like equation in Laplace domain instead of solving dual integral equations. Analytical solutions of DSIFs in Laplace domain are derived by Wiener-Hopf technique and the numerical solutions of DSIFs in time domain are obtained by Talbot algorithm. The effects of four parameters α, β, b1, b2 of the fractional dif- ferential constitutive model on DSIFs are discussed. The numerical results show that the present fractional differential constitutive model can well describe the behavior of DSIFs of anti-plane fracture in viscoelastic materials, and the model is also compatible with solutions of DSIFs of anti-plane fracture in elastic materials.展开更多
Isotopic fractionation is the basis of tracing the water cycle using hydrogen and oxygen isotopes. Isotopic fractionation factors in water evaporating from free water bodies are mainly affected by temperature and rela...Isotopic fractionation is the basis of tracing the water cycle using hydrogen and oxygen isotopes. Isotopic fractionation factors in water evaporating from free water bodies are mainly affected by temperature and relative humidity, and vary significantly with these atmospheric factors over the course of a day. The evaporation rate （E） can reveal the effects of atmospheric factors. Therefore, there should be a certain functional relationship between isotopic fractionation factors and E. An average isotopic fractionation factor （ t~＊ ） was defined to describe isotopic differences between vapor and liquid phases in evaporation with time intervals of days. The relationship between or＊ and E based on the isotopic mass balance was investigated through an evaporation pan experiment with no inflow. The experimental results showed that the isotopic compositions of residual water were more enriched with time; tr＊ was affected by air temperature, relative humidity, and other atmospheric factors, and had a strong functional relation with E. The values of 0~＊ can be easily calculated with the known values of E, the initial volume of water in the pan, and isotopic compositions of residual water.展开更多
Several important equilibrium Si isotope fractionation factors among minerals,organic molecules and the H_4SiO_4 solution are complemented to facilitate the explanation of the distributions of Si isotopes in Earth'...Several important equilibrium Si isotope fractionation factors among minerals,organic molecules and the H_4SiO_4 solution are complemented to facilitate the explanation of the distributions of Si isotopes in Earth's surface environments.The results reveal that,in comparison to aqueous H_4SiO_4,heavy Si isotopes will be significantly enriched in secondary silicate minerals.On the contrary,quadra-coordinated organosilicon complexes are enriched in light silicon isotope relative to the solution.The extent of ^(28)Si-enrichment in hyper-coordinated organosilicon complexes was found to be the largest.In addition,the large kinetic isotope effect associated with the polymerization of monosilicic acid and dimer was calculated,and the results support the previous statement that highly ^(28)Sienrichment in the formation of amorphous quartz precursor contributes to the discrepancy between theoretical calculations and field observations.With the equilibrium Si isotope fractionation factors provided here,Si isotope distributions in many of Earth's surface systems can be explained.For example,the change of bulk soil δ^(30)Si can be predicted as a concave pattern with respect to the weathering degree,with the minimum value where allophane completely dissolves and the total amount of sesquioxides and poorly crystalline minerals reaches their maximum.When,under equilibrium conditions,the well-crystallized clays start to precipitate from the pore solutions,the bulk soil δ^(30)Si will increase again and reach a constant value.Similarly,the precipitation of crystalline smectite and the dissolution of poorly crystalline kaolinite may explain the δ^(30)Si variations in the ground water profile.The equilibrium Si isotope fractionations among the quadracoordinated organosilicon complexes and the H_4SiO_4solution may also shed light on the Si isotope distributions in the Si-accumulating plants.展开更多
This paper presents a new proof of a charaterization of fractional (g, f)-factors of a graph in which multiple edges are allowed. From the proof a polynomial algorithm for finding the fractional (g, f)-factor can be i...This paper presents a new proof of a charaterization of fractional (g, f)-factors of a graph in which multiple edges are allowed. From the proof a polynomial algorithm for finding the fractional (g, f)-factor can be induced.展开更多
There are many accelerating convergence factors (ACFs) for limit periodic continued fraction K(an/1)(an→a≠0). In this paper, some characteristics and comparative theorems are ob tained on ACFs. Two results are given...There are many accelerating convergence factors (ACFs) for limit periodic continued fraction K(an/1)(an→a≠0). In this paper, some characteristics and comparative theorems are ob tained on ACFs. Two results are given for most frequently used ACFs.展开更多
Objective Despite the fact that the bioavailability of trace metals indicated by their speciation has been an indispensable parameter in the assessment and treatment of the environmental pollution of trace metals, ma...Objective Despite the fact that the bioavailability of trace metals indicated by their speciation has been an indispensable parameter in the assessment and treatment of the environmental pollution of trace metals, many studies have suggested that the bioavailability of trace metals may change according to the conditions of the environment, and the speciation of trace metals can also transform between some fractions. These transformations are related with these factors such as the compositions, microorganism, time, and other physical-chemical conditions of the system. Our work aims to systematically investigate and probe the factors to affect the transformation aside from analysis at certain time-place. The results of these understanding and investigations can be used for reasonably determining the allocation of financial and technical resources in natural and engineered processes, with bringing about inspirations from the evolution of the speciation of the trace metals on environmental impacts.展开更多
In this paper, we introduce a new definition of fractional derivative which contains a fractional factor, and its physical meanings are given. When studying the fractional Schrdinger equation(FSE) with this form of fr...In this paper, we introduce a new definition of fractional derivative which contains a fractional factor, and its physical meanings are given. When studying the fractional Schrdinger equation(FSE) with this form of fractional derivative, the result shows that under the description of time FSE with fractional factor, the probability of finding a particle in the whole space is still conserved. By using this new definition to construct space FSE, we achieve a continuous transition from standard Schrdinger equation to the fractional one. When applying this form of Schrdinger equation to a particle in an infinite symmetrical square potential well, we find that the probability density distribution loses spatial symmetry and shows a kind of attenuation property. For the situation of a one-dimensional infinite δ potential well,the first derivative of time-independent wave function Φ to space coordinate x can be continuous everywhere when the particle is at some special discrete energy levels, which is much different from the standard Schrdinger equation.展开更多
In this paper the properties of some maximum fractional [0, k]-factors of graphs are presented. And consequently some results on fractional matchings and fractional 1-factors are generalized and a characterization of ...In this paper the properties of some maximum fractional [0, k]-factors of graphs are presented. And consequently some results on fractional matchings and fractional 1-factors are generalized and a characterization of fractional k-factors is obtained.展开更多
A key issue of applying remotely sensed data to estimate evapotranspiration （ET） for water management is extrapolating instantaneous latent heat flux （LE） at satellite over-passing time to daily ET total. At prese...A key issue of applying remotely sensed data to estimate evapotranspiration （ET） for water management is extrapolating instantaneous latent heat flux （LE） at satellite over-passing time to daily ET total. At present, the most commonly used extrapolation methods have the same assumption that evaporative fraction （EF） can be treated as constant during daytime （so-called EF self-preservation）. However, large errors are reported by many documents over various ecosystems with the same approach, which indicates that further analysis of the diurnal pattern of EF is still necessary. The aim of this study is to examine the diurnal pattern of EF under fair weather conditions, then to analyze the dependencies of EF to meteorological and plant factors. Long-term flux observations at four sites over semi-arid and semi-humid climate regions in the northern China are used to analyze the EF diumal pattern. Results show that the EF self-preservation assumption no longer holds over growing seasons of crops. However, the ratio of reference ET to available energy is almost constant during the daytime, which implies the climate factors do not have much effect on the variability of EF. The analysis of diurnal pattern of air temperature, vapor pressure deficiency （VPD）, and relative humidity （RH） confirms the assumption that ET diurnal pattern is mainly influenced by stomatal regulation.展开更多
AIM To quantify the preventive fraction of physical fitness on the risk factors in patients with cardiovascular diseases(CVDs).METHODS A total of 249 subjects(205 men and 44 women) suffering from CVD were categorized ...AIM To quantify the preventive fraction of physical fitness on the risk factors in patients with cardiovascular diseases(CVDs).METHODS A total of 249 subjects(205 men and 44 women) suffering from CVD were categorized into four groups, according to their percentage of physical fitness. We calculated the odds ratio to obtain the preventive fraction in order to evaluate the impact of the physical fitness level on the risk factors(i.e., abdominal obesity, depression, diabetes, dyslipidemia, hypertension, obesity, overweight and smoking).RESULTS It is observed that a normal physical fitness level is sufficient to induce a preventive action on abdominal obesity(38%), diabetes(12%), hypertension(33%), obesity(12%) and overweight(11%). Also, the preventive fraction increases with the level of physical fitness, in particular for hypertension(36%) and overweight(16%). A high physical fitness level does not necessarily induce a preventive action in most risk factors, excluding depression. CONCLUSION This is the first study which demonstrates that reaching a normal physical fitness level is enough to induce a protection for some risk factors, despite having a CVD.展开更多
In this paper, we consider the relationship between the binding number and the existence of fractional k-factors of graphs. The binding number of G is defined by Woodall as bind(G)=min{ | NG(X) || X |:∅≠X⊆V(G) }. It ...In this paper, we consider the relationship between the binding number and the existence of fractional k-factors of graphs. The binding number of G is defined by Woodall as bind(G)=min{ | NG(X) || X |:∅≠X⊆V(G) }. It is proved that a graph G has a fractional 1-factor if bind(G)≥1and has a fractional k-factor if bind(G)≥k−1k. Furthermore, it is showed that both results are best possible in some sense.展开更多
We consider plus-operators in Krein spaces and generated operator linear fractional relations of the following form: . We study some special type of factorization for plus-operators T, among them the following one: T ...We consider plus-operators in Krein spaces and generated operator linear fractional relations of the following form: . We study some special type of factorization for plus-operators T, among them the following one: T = BU, where B is a lower triangular plus-operator, U is a J-unitary operator. We apply the above factorization to the study of basical properties of relations (1), in particular, convexity and compactness of their images with respect to the weak operator topology. Obtained results we apply to the known Koenigs embedding problem, the Krein-Phillips problem of existing of invariant semidefinite subspaces for some families of plus-operators and to some other fields.展开更多
Background Endogenous aldehyde damages DNA and potentiates an ageing phenotype. The aldehyde dehydrogenase 2(ALDH2) rs671 polymorphism has a prevalence of 30%–50% in Asian populations. In this study, we aimed to anal...Background Endogenous aldehyde damages DNA and potentiates an ageing phenotype. The aldehyde dehydrogenase 2(ALDH2) rs671 polymorphism has a prevalence of 30%–50% in Asian populations. In this study, we aimed to analyze risk factors contributing to the development of heart failure with preserved ejection fraction(HFpEF) along with the genetic exposure in Chinese patients hospitalized with cardiovascular diseases(CVD). Methods From July 2017 to October 2018, a total of 770 consecutive Chinese patients with normal left ventricular ejection fractions(LVEF) and established CVD(hypertension, coronary heart diseases, or diabetes) were enrolled in this prospective cross-sectional study. HFpEF was defined by the presence of at least one of symptom(dyspnoea and fatigue) or sign(rales and ankle swelling) related to heart failure;N-terminal pro-B-Type natriuretic peptide(NT pro-BNP ≥ 280 pg/mL);LVEF ≥ 50%;and at least one criterion related to elevated ventricular filling pressure or diastolic dysfunction(left atrial diameter > 40 mm, E/E’ ≥ 13, E’/A’ < 1 or concurrent atrial fibrillation). Logistic regression was performed to yield adjusted odds ratios(ORs) for HFp EF incidence associated with traditional and/or genetic exposures. Results Finally, among 770 patients with CVD, 92(11.9%) patients were classified into the HFpEF group according to the diagnostic criteria. The mean age of the participants was 67 ± 12 years, and 278(36.1%) patients were females. A total of 303(39.4%) patients were ALDH2*2 variant carriers. In the univariate analysis, eight exposures were found to be associated with HFpEF: atrial fibrillation, ALDH2*2 variants, hypertension, age, anaemia, smoking, alcohol consumption and sex. Multivariable logistic regression showed that 4 ‘A’ variables(atrial fibrillation, ALDH2*2 variants, age and anaemia) were significantly associated with an increased risk of HFpEF. Atrial fibrillation was associated with a 3.8-fold increased HFpEF risk(95% CI: 2.21–6.61, P < 0.001), and the other three exposures associated with increased HFpEF risk were the ALDH2*2 variant(OR = 2.41, 95% CI: 1.49–3.87, P < 0.001), age(OR = 2.14, 95% CI: 1.27–3.60, P = 0.004), and anaemia(OR = 1.79, 95% CI: 1.05–3.03, P = 0.032). These four variables predicted HFpEF incidence in Chinese CVD patients(C-statistic = 0.745, 95% CI: 0.691–0.800, P < 0.001). Conclusions 4 A traits(atrial fibrillation, ALDH2*2 variants, age and anaemia) were associated with an increased risk of HFpEF in Chinese CVD patients. Our results provide potential clues to the aetiology, pathophysiology and therapeutic targets of HFpEF.展开更多
In the paper, a general framework for large scale modeling of macroeconomic and financial time series is introduced. The proposed approach is characterized by simplicity of implementation, performing well independentl...In the paper, a general framework for large scale modeling of macroeconomic and financial time series is introduced. The proposed approach is characterized by simplicity of implementation, performing well independently of persistence and heteroskedasticity properties, accounting for common deterministic and stochastic factors. Monte Carlo results strongly support the proposed methodology, validating its use also for relatively small cross-sectional and temporal samples.展开更多
The fractional volumetric lattice Boltzmann method with much better stability was used to simulate two-chmensional cavity flows. Because the effective viscosity was reduced by the fraction factor, it is very effective...The fractional volumetric lattice Boltzmann method with much better stability was used to simulate two-chmensional cavity flows. Because the effective viscosity was reduced by the fraction factor, it is very effective for simulating high Reynolds number flows. Simulations were carried out on a uniform grids system. The stream lines and the velocity profiles obtained from the simulations agree well with the standard lattice Boltzmann method simulations. Comparisons of detailed flow patterns with other studies via location of vortex centers are also satisfactory.展开更多
Tenorite is an oxide of cupper which has been well documented on its structure, force constants and spectrum. Based on the isotopic shifts of its spectrum calculated from the force constants of tenorite, its reduced p...Tenorite is an oxide of cupper which has been well documented on its structure, force constants and spectrum. Based on the isotopic shifts of its spectrum calculated from the force constants of tenorite, its reduced partition function ratios were calculated, from which an oxygen isotopic fractionation curve between tenorite and water was obtained:10sin.= 2. 51X2 - 14. 87X + 6. 31 (X = 103/T) Oxygen isotopic fractionation of tenorite was also calculated with the modified increment method of Zheng (1991), and another equation was obtained: 10sin.= 2. 89X2 - 13. 10X + 3. 92 (X = 103/T) Calculated results of the two different models were fitted and possible deviation involved in the calculation was also discussed.展开更多
This paper proposes three new attacks. In the first attack we consider the class of the public exponents satisfying an equation e X-N Y ＋（ap^r＋ bq^r）Y = Z for suitably small positive integers a, b. Applying contin...This paper proposes three new attacks. In the first attack we consider the class of the public exponents satisfying an equation e X-N Y ＋（ap^r＋ bq^r）Y = Z for suitably small positive integers a, b. Applying continued fractions we show thatY/Xcan be recovered among the convergents of the continued fraction expansion of e/N. Moreover, we show that the number of such exponents is at least N^（2/（r＋1）-ε）where ε≥ 0 is arbitrarily small for large N. The second and third attacks works upon k RSA public keys（N_i, e_i） when there exist k relations of the form e_ix-N_iy_i ＋（ap_i^r ＋ bq_i^r ）y_i = z_i or of the form e_ix_i-N_iy ＋（ap_i^r ＋ bq_i^r ）y = z_i and the parameters x, x_i, y, y_i, z_i are suitably small in terms of the prime factors of the moduli. We apply the LLL algorithm, and show that our strategy enables us to simultaneously factor k prime power RSA moduli.展开更多
Objective： To provide an evidence-based, consistent assessment of the burden of breast cancer attributable to reproductive factors （RFs, including nulliparity, mean number of children, age at first birth and breastf...Objective： To provide an evidence-based, consistent assessment of the burden of breast cancer attributable to reproductive factors （RFs, including nulliparity, mean number of children, age at first birth and breastfeeding）, use of oral contraceptives （OCs, restricted to the age group of 15-49 years）, and hormone replacement therapy （HRT）, as well as of the burden of ovarian cancer attributable to the mean number of children in China in 2005. Methods： We derived the prevalence of these risk factors and the relative risk of breast and ovarian cancer from national surveys or large-scale studies conducted in China. In the case of RFs, we compared the exposure distributions in 2001 and counterfactual exposure. Results： Exposure of RFs in 2002 was found to account for 6.74% of breast cancer, corresponding to 9,617 cases and 2,769 deaths, and for 2.78% of ovarian cancer （712 cases, 294 deaths）. The decrease in mean number of children alone was responsible for 1.47% of breast cancer and 2.78% of ovarian cancer. The prevalence of OC use was 1.74% and the population attributable fraction （PAF） of breast cancer was 0.71%, corresponding to 310 cases and 90 deaths. The PAF of breast cancer due to HRT was 0.31%, resulting in 297 cases and 85 deaths. Conclusion： RFs changes in China contributed to a sizable fraction of breast and ovarian cancer incidence and mortality, whereas HRT and OCs accounted for relatively low incidence of breast cancer in China.展开更多
Objectives To evaluate the effect of different styles of coronary heart disease （CHD）, different regions of acute myocardial infarction （AMI）, its risk factors and branches of coronary stenosis on left ventricular...Objectives To evaluate the effect of different styles of coronary heart disease （CHD）, different regions of acute myocardial infarction （AMI）, its risk factors and branches of coronary stenosis on left ventricular remodeling and dysfunction by applying echocardiography. Methods 251 patients with CHD and 96 patients without CHD （NoCHD） were verified by selective coronary angiography. CHD patients were divided into stable angina pectoris （SAP） 26, unstable angina pectoris（UAP） 53, acute myocardial infarction （AMI） 140 and old myocardial infarction （OMI） 30 based on clinical situation, cTnT, cardiac enzyme and ECG. AMI patients were further divided into subgroups including acute anterior myocardial infarct （Aa,n = 53）, acute inferior myocardial infarction （Ai, n=54） and Aa＋Ai （n=33） based on ECG. Cardiac parameters： end-diastolic interventricular septum thickness（IVSd）, end-diastolic left ventricular internal diameter （LVd）, left ventricular mass （LM）, end-diastolic left ventricular volume （EDV）, end-systolic left ventricular volume （ESV） and left ventricular ejection fraction（LVEF） were measured by ACUSON 128XP/10 echocardiography. Multiples linear regression analyses were performed to test statistical associations between LVEF and the involved branches of coronary stenosis, blood pressure, lipids, glucose and etc after onset of myocardial infarction. Results EDV and ESV were increased and LVEF decreased on patients with AMI,OMI and UAP （P〈0.05-0.0001）. LM was mainly increased in patients with OMI （P〈0.01） and LVd was mainly enlarged in patients with AMI. EF was significantly decreased and EDV, ESV, LM and LVd were remarkably increased in AMI patients with Aa and Aa＋Ai. With the multiple linear regression analyses by SPSS software, we found that LVEF was negatively correlated to the involved branches of coronary stenosis as well as to systolic blood pressure after onset of myocardial infarction while there was no significant correlation between LVEF and other factors. LVEF was significantly decreased, and LVd and LM increased in AMI patients with antecedent hypertension, compared to patients without hypertension （P〈0.001）. Conclusions Effects of different styles of CHD and different regions of AMI on left ventricular remodeling and cardiac function are different. Myocardial infarction, especially Aa and Aa＋Ai, is one of the most important causes of left ventricular remodeling and cardiac dysfunction. Multiple vessel stenosis and systolic blood pressure at the onset of myocardial infarction reduce LVEF in AMI patients. Antecedent hypertension may accelerate the effect of AMI on cardiac remodeling and dysfunction. Therefore primary and secondary preventions of CHD are critical for protecting heart from remodeling and dysfunction.展开更多
Objective: To investigate the relationship between platelet-derived growth factor-A (PDGF-A) and atrial fibrosis in patients who have developed atrial fibrillation (AF) secondary to rheumatic valvular disease. Methods...Objective: To investigate the relationship between platelet-derived growth factor-A (PDGF-A) and atrial fibrosis in patients who have developed atrial fibrillation (AF) secondary to rheumatic valvular disease. Methods: 84 selected patients participated in the current study who have developed rheumatic heart disease and were going to have a cardiac surgical operation. In the current study, whole subjects were divided into two group, they were atrial fibrillation (AF) group (the quantity is thirty-nine) and sinus rhythm (SR) group (the quantity is forty-five). Before the operation, complete clinical data was available for the whole patients. During the operation, the right atrial tissue (0.3 - 0.5 mm<sup>3</sup>) was disserted from every patient. Right atrial fibrosis was observed by Masson staining and the distribution of PDGF-A in right atrium specimen was observed by immunohistochemistry. RT-PCR techniques were applied to admeasure the mRNA expressions of PDGF-A in patients’ atrial tissue. At the same time, western-Blot techniques were employed to admeasure the protein expressions of PDGF-A. Results: In baseline clinical characteristics, in both AF group and SR group, there was no apparently difference between them (P > 0.05);compared with SR group, the diameters of left atrium and right atrium in AF group were apparently increased (P Conclusion: Atrial remodeling plays an important role in patients with valvular atrial fibrillation;PDGF-A in patients with AF was highly expressed in the right atrial, and was closely related with atrial fibrosis.展开更多
基金supported by the National Natural Science Foundation of China(11072060)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Fractional differential constitutive relationships are introduced to depict the history of dynamic stress inten- sity factors （DSIFs） for a semi-infinite crack in infinite viscoelastic material subjected to anti-plane shear impact load. The basic equations which govern the anti-plane deformation behavior are converted to a fractional wave-like equation. By utilizing Laplace and Fourier integral transforms, the fractional wave-like equation is cast into an ordinary differential equation （ODE）. The unknown function in the solution of ODE is obtained by applying Fourier transform directly to the boundary conditions of fractional wave-like equation in Laplace domain instead of solving dual integral equations. Analytical solutions of DSIFs in Laplace domain are derived by Wiener-Hopf technique and the numerical solutions of DSIFs in time domain are obtained by Talbot algorithm. The effects of four parameters α, β, b1, b2 of the fractional dif- ferential constitutive model on DSIFs are discussed. The numerical results show that the present fractional differential constitutive model can well describe the behavior of DSIFs of anti-plane fracture in viscoelastic materials, and the model is also compatible with solutions of DSIFs of anti-plane fracture in elastic materials.
基金supported by the National Natural Science Foundation of China (Grants No.50679024,40901015,and 41001011)the Fundamental Research Funds for the Central Universities (Grants No.B1020072 and B1020062)+2 种基金the Ph. D. Programs Foundation of the Ministry of Education of China (Grant No.20090094120008)the Special Fund of the State Key Laboratory of China (Grant No.2009586412)the Science Foundation of the HydroChina Chengdu Engineering Corporation (Grant No.P058)
文摘Isotopic fractionation is the basis of tracing the water cycle using hydrogen and oxygen isotopes. Isotopic fractionation factors in water evaporating from free water bodies are mainly affected by temperature and relative humidity, and vary significantly with these atmospheric factors over the course of a day. The evaporation rate （E） can reveal the effects of atmospheric factors. Therefore, there should be a certain functional relationship between isotopic fractionation factors and E. An average isotopic fractionation factor （ t~＊ ） was defined to describe isotopic differences between vapor and liquid phases in evaporation with time intervals of days. The relationship between or＊ and E based on the isotopic mass balance was investigated through an evaporation pan experiment with no inflow. The experimental results showed that the isotopic compositions of residual water were more enriched with time; tr＊ was affected by air temperature, relative humidity, and other atmospheric factors, and had a strong functional relation with E. The values of 0~＊ can be easily calculated with the known values of E, the initial volume of water in the pan, and isotopic compositions of residual water.
基金the funding support from the 973 Program(2014CB440904)CAS/SAFEA International Partnership Program for Creative Research Teams(Intraplate Mineralization Research Team,KZZD-EW-TZ-20)Chinese NSF projects(41173023,41225012,41490635,41530210)
文摘Several important equilibrium Si isotope fractionation factors among minerals,organic molecules and the H_4SiO_4 solution are complemented to facilitate the explanation of the distributions of Si isotopes in Earth's surface environments.The results reveal that,in comparison to aqueous H_4SiO_4,heavy Si isotopes will be significantly enriched in secondary silicate minerals.On the contrary,quadra-coordinated organosilicon complexes are enriched in light silicon isotope relative to the solution.The extent of ^(28)Si-enrichment in hyper-coordinated organosilicon complexes was found to be the largest.In addition,the large kinetic isotope effect associated with the polymerization of monosilicic acid and dimer was calculated,and the results support the previous statement that highly ^(28)Sienrichment in the formation of amorphous quartz precursor contributes to the discrepancy between theoretical calculations and field observations.With the equilibrium Si isotope fractionation factors provided here,Si isotope distributions in many of Earth's surface systems can be explained.For example,the change of bulk soil δ^(30)Si can be predicted as a concave pattern with respect to the weathering degree,with the minimum value where allophane completely dissolves and the total amount of sesquioxides and poorly crystalline minerals reaches their maximum.When,under equilibrium conditions,the well-crystallized clays start to precipitate from the pore solutions,the bulk soil δ^(30)Si will increase again and reach a constant value.Similarly,the precipitation of crystalline smectite and the dissolution of poorly crystalline kaolinite may explain the δ^(30)Si variations in the ground water profile.The equilibrium Si isotope fractionations among the quadracoordinated organosilicon complexes and the H_4SiO_4solution may also shed light on the Si isotope distributions in the Si-accumulating plants.
基金This work is supported by NNSF of ChinaRFDP of Higher Education
文摘This paper presents a new proof of a charaterization of fractional (g, f)-factors of a graph in which multiple edges are allowed. From the proof a polynomial algorithm for finding the fractional (g, f)-factor can be induced.
基金Supported by the National Natural Science Foundation of china
文摘There are many accelerating convergence factors (ACFs) for limit periodic continued fraction K(an/1)(an→a≠0). In this paper, some characteristics and comparative theorems are ob tained on ACFs. Two results are given for most frequently used ACFs.
基金funded by the National Natural Science Foundation of China(grant No.41572329)
文摘Objective Despite the fact that the bioavailability of trace metals indicated by their speciation has been an indispensable parameter in the assessment and treatment of the environmental pollution of trace metals, many studies have suggested that the bioavailability of trace metals may change according to the conditions of the environment, and the speciation of trace metals can also transform between some fractions. These transformations are related with these factors such as the compositions, microorganism, time, and other physical-chemical conditions of the system. Our work aims to systematically investigate and probe the factors to affect the transformation aside from analysis at certain time-place. The results of these understanding and investigations can be used for reasonably determining the allocation of financial and technical resources in natural and engineered processes, with bringing about inspirations from the evolution of the speciation of the trace metals on environmental impacts.
基金Supported by National Natural Science Foundation of China under Grant Nos.11472247 and 11872335
文摘In this paper, we introduce a new definition of fractional derivative which contains a fractional factor, and its physical meanings are given. When studying the fractional Schrdinger equation(FSE) with this form of fractional derivative, the result shows that under the description of time FSE with fractional factor, the probability of finding a particle in the whole space is still conserved. By using this new definition to construct space FSE, we achieve a continuous transition from standard Schrdinger equation to the fractional one. When applying this form of Schrdinger equation to a particle in an infinite symmetrical square potential well, we find that the probability density distribution loses spatial symmetry and shows a kind of attenuation property. For the situation of a one-dimensional infinite δ potential well,the first derivative of time-independent wave function Φ to space coordinate x can be continuous everywhere when the particle is at some special discrete energy levels, which is much different from the standard Schrdinger equation.
基金This work is supported by NSFC (10471078.10201019)RSDP (20040422004) of China
文摘In this paper the properties of some maximum fractional [0, k]-factors of graphs are presented. And consequently some results on fractional matchings and fractional 1-factors are generalized and a characterization of fractional k-factors is obtained.
基金supported by the the National Natural Science Funds for Distinguished Yong Scholar,China(51025931)the National Natural Science Foundation of China(50939004)
文摘A key issue of applying remotely sensed data to estimate evapotranspiration （ET） for water management is extrapolating instantaneous latent heat flux （LE） at satellite over-passing time to daily ET total. At present, the most commonly used extrapolation methods have the same assumption that evaporative fraction （EF） can be treated as constant during daytime （so-called EF self-preservation）. However, large errors are reported by many documents over various ecosystems with the same approach, which indicates that further analysis of the diurnal pattern of EF is still necessary. The aim of this study is to examine the diurnal pattern of EF under fair weather conditions, then to analyze the dependencies of EF to meteorological and plant factors. Long-term flux observations at four sites over semi-arid and semi-humid climate regions in the northern China are used to analyze the EF diumal pattern. Results show that the EF self-preservation assumption no longer holds over growing seasons of crops. However, the ratio of reference ET to available energy is almost constant during the daytime, which implies the climate factors do not have much effect on the variability of EF. The analysis of diurnal pattern of air temperature, vapor pressure deficiency （VPD）, and relative humidity （RH） confirms the assumption that ET diurnal pattern is mainly influenced by stomatal regulation.
文摘AIM To quantify the preventive fraction of physical fitness on the risk factors in patients with cardiovascular diseases(CVDs).METHODS A total of 249 subjects(205 men and 44 women) suffering from CVD were categorized into four groups, according to their percentage of physical fitness. We calculated the odds ratio to obtain the preventive fraction in order to evaluate the impact of the physical fitness level on the risk factors(i.e., abdominal obesity, depression, diabetes, dyslipidemia, hypertension, obesity, overweight and smoking).RESULTS It is observed that a normal physical fitness level is sufficient to induce a preventive action on abdominal obesity(38%), diabetes(12%), hypertension(33%), obesity(12%) and overweight(11%). Also, the preventive fraction increases with the level of physical fitness, in particular for hypertension(36%) and overweight(16%). A high physical fitness level does not necessarily induce a preventive action in most risk factors, excluding depression. CONCLUSION This is the first study which demonstrates that reaching a normal physical fitness level is enough to induce a protection for some risk factors, despite having a CVD.
文摘In this paper, we consider the relationship between the binding number and the existence of fractional k-factors of graphs. The binding number of G is defined by Woodall as bind(G)=min{ | NG(X) || X |:∅≠X⊆V(G) }. It is proved that a graph G has a fractional 1-factor if bind(G)≥1and has a fractional k-factor if bind(G)≥k−1k. Furthermore, it is showed that both results are best possible in some sense.
文摘We consider plus-operators in Krein spaces and generated operator linear fractional relations of the following form: . We study some special type of factorization for plus-operators T, among them the following one: T = BU, where B is a lower triangular plus-operator, U is a J-unitary operator. We apply the above factorization to the study of basical properties of relations (1), in particular, convexity and compactness of their images with respect to the weak operator topology. Obtained results we apply to the known Koenigs embedding problem, the Krein-Phillips problem of existing of invariant semidefinite subspaces for some families of plus-operators and to some other fields.
基金supported by the he National Natural Science Foundation of China (No. 81770441, No. 81700398, No. 81970309)Nanjing Municipal Healthcare Grant YKK16127
文摘Background Endogenous aldehyde damages DNA and potentiates an ageing phenotype. The aldehyde dehydrogenase 2(ALDH2) rs671 polymorphism has a prevalence of 30%–50% in Asian populations. In this study, we aimed to analyze risk factors contributing to the development of heart failure with preserved ejection fraction(HFpEF) along with the genetic exposure in Chinese patients hospitalized with cardiovascular diseases(CVD). Methods From July 2017 to October 2018, a total of 770 consecutive Chinese patients with normal left ventricular ejection fractions(LVEF) and established CVD(hypertension, coronary heart diseases, or diabetes) were enrolled in this prospective cross-sectional study. HFpEF was defined by the presence of at least one of symptom(dyspnoea and fatigue) or sign(rales and ankle swelling) related to heart failure;N-terminal pro-B-Type natriuretic peptide(NT pro-BNP ≥ 280 pg/mL);LVEF ≥ 50%;and at least one criterion related to elevated ventricular filling pressure or diastolic dysfunction(left atrial diameter > 40 mm, E/E’ ≥ 13, E’/A’ < 1 or concurrent atrial fibrillation). Logistic regression was performed to yield adjusted odds ratios(ORs) for HFp EF incidence associated with traditional and/or genetic exposures. Results Finally, among 770 patients with CVD, 92(11.9%) patients were classified into the HFpEF group according to the diagnostic criteria. The mean age of the participants was 67 ± 12 years, and 278(36.1%) patients were females. A total of 303(39.4%) patients were ALDH2*2 variant carriers. In the univariate analysis, eight exposures were found to be associated with HFpEF: atrial fibrillation, ALDH2*2 variants, hypertension, age, anaemia, smoking, alcohol consumption and sex. Multivariable logistic regression showed that 4 ‘A’ variables(atrial fibrillation, ALDH2*2 variants, age and anaemia) were significantly associated with an increased risk of HFpEF. Atrial fibrillation was associated with a 3.8-fold increased HFpEF risk(95% CI: 2.21–6.61, P < 0.001), and the other three exposures associated with increased HFpEF risk were the ALDH2*2 variant(OR = 2.41, 95% CI: 1.49–3.87, P < 0.001), age(OR = 2.14, 95% CI: 1.27–3.60, P = 0.004), and anaemia(OR = 1.79, 95% CI: 1.05–3.03, P = 0.032). These four variables predicted HFpEF incidence in Chinese CVD patients(C-statistic = 0.745, 95% CI: 0.691–0.800, P < 0.001). Conclusions 4 A traits(atrial fibrillation, ALDH2*2 variants, age and anaemia) were associated with an increased risk of HFpEF in Chinese CVD patients. Our results provide potential clues to the aetiology, pathophysiology and therapeutic targets of HFpEF.
文摘In the paper, a general framework for large scale modeling of macroeconomic and financial time series is introduced. The proposed approach is characterized by simplicity of implementation, performing well independently of persistence and heteroskedasticity properties, accounting for common deterministic and stochastic factors. Monte Carlo results strongly support the proposed methodology, validating its use also for relatively small cross-sectional and temporal samples.
文摘The fractional volumetric lattice Boltzmann method with much better stability was used to simulate two-chmensional cavity flows. Because the effective viscosity was reduced by the fraction factor, it is very effective for simulating high Reynolds number flows. Simulations were carried out on a uniform grids system. The stream lines and the velocity profiles obtained from the simulations agree well with the standard lattice Boltzmann method simulations. Comparisons of detailed flow patterns with other studies via location of vortex centers are also satisfactory.
文摘Tenorite is an oxide of cupper which has been well documented on its structure, force constants and spectrum. Based on the isotopic shifts of its spectrum calculated from the force constants of tenorite, its reduced partition function ratios were calculated, from which an oxygen isotopic fractionation curve between tenorite and water was obtained:10sin.= 2. 51X2 - 14. 87X + 6. 31 (X = 103/T) Oxygen isotopic fractionation of tenorite was also calculated with the modified increment method of Zheng (1991), and another equation was obtained: 10sin.= 2. 89X2 - 13. 10X + 3. 92 (X = 103/T) Calculated results of the two different models were fitted and possible deviation involved in the calculation was also discussed.
文摘This paper proposes three new attacks. In the first attack we consider the class of the public exponents satisfying an equation e X-N Y ＋（ap^r＋ bq^r）Y = Z for suitably small positive integers a, b. Applying continued fractions we show thatY/Xcan be recovered among the convergents of the continued fraction expansion of e/N. Moreover, we show that the number of such exponents is at least N^（2/（r＋1）-ε）where ε≥ 0 is arbitrarily small for large N. The second and third attacks works upon k RSA public keys（N_i, e_i） when there exist k relations of the form e_ix-N_iy_i ＋（ap_i^r ＋ bq_i^r ）y_i = z_i or of the form e_ix_i-N_iy ＋（ap_i^r ＋ bq_i^r ）y = z_i and the parameters x, x_i, y, y_i, z_i are suitably small in terms of the prime factors of the moduli. We apply the LLL algorithm, and show that our strategy enables us to simultaneously factor k prime power RSA moduli.
基金supported by International Agency for Research on Cancer (Lyon, France) (No. CRA No GEE/08/19)supported in part by the Fogarty International Clinical Research Scholars and Fellows Program at Vanderbilt University (R24 TW007988)
文摘Objective： To provide an evidence-based, consistent assessment of the burden of breast cancer attributable to reproductive factors （RFs, including nulliparity, mean number of children, age at first birth and breastfeeding）, use of oral contraceptives （OCs, restricted to the age group of 15-49 years）, and hormone replacement therapy （HRT）, as well as of the burden of ovarian cancer attributable to the mean number of children in China in 2005. Methods： We derived the prevalence of these risk factors and the relative risk of breast and ovarian cancer from national surveys or large-scale studies conducted in China. In the case of RFs, we compared the exposure distributions in 2001 and counterfactual exposure. Results： Exposure of RFs in 2002 was found to account for 6.74% of breast cancer, corresponding to 9,617 cases and 2,769 deaths, and for 2.78% of ovarian cancer （712 cases, 294 deaths）. The decrease in mean number of children alone was responsible for 1.47% of breast cancer and 2.78% of ovarian cancer. The prevalence of OC use was 1.74% and the population attributable fraction （PAF） of breast cancer was 0.71%, corresponding to 310 cases and 90 deaths. The PAF of breast cancer due to HRT was 0.31%, resulting in 297 cases and 85 deaths. Conclusion： RFs changes in China contributed to a sizable fraction of breast and ovarian cancer incidence and mortality, whereas HRT and OCs accounted for relatively low incidence of breast cancer in China.
文摘Objectives To evaluate the effect of different styles of coronary heart disease （CHD）, different regions of acute myocardial infarction （AMI）, its risk factors and branches of coronary stenosis on left ventricular remodeling and dysfunction by applying echocardiography. Methods 251 patients with CHD and 96 patients without CHD （NoCHD） were verified by selective coronary angiography. CHD patients were divided into stable angina pectoris （SAP） 26, unstable angina pectoris（UAP） 53, acute myocardial infarction （AMI） 140 and old myocardial infarction （OMI） 30 based on clinical situation, cTnT, cardiac enzyme and ECG. AMI patients were further divided into subgroups including acute anterior myocardial infarct （Aa,n = 53）, acute inferior myocardial infarction （Ai, n=54） and Aa＋Ai （n=33） based on ECG. Cardiac parameters： end-diastolic interventricular septum thickness（IVSd）, end-diastolic left ventricular internal diameter （LVd）, left ventricular mass （LM）, end-diastolic left ventricular volume （EDV）, end-systolic left ventricular volume （ESV） and left ventricular ejection fraction（LVEF） were measured by ACUSON 128XP/10 echocardiography. Multiples linear regression analyses were performed to test statistical associations between LVEF and the involved branches of coronary stenosis, blood pressure, lipids, glucose and etc after onset of myocardial infarction. Results EDV and ESV were increased and LVEF decreased on patients with AMI,OMI and UAP （P〈0.05-0.0001）. LM was mainly increased in patients with OMI （P〈0.01） and LVd was mainly enlarged in patients with AMI. EF was significantly decreased and EDV, ESV, LM and LVd were remarkably increased in AMI patients with Aa and Aa＋Ai. With the multiple linear regression analyses by SPSS software, we found that LVEF was negatively correlated to the involved branches of coronary stenosis as well as to systolic blood pressure after onset of myocardial infarction while there was no significant correlation between LVEF and other factors. LVEF was significantly decreased, and LVd and LM increased in AMI patients with antecedent hypertension, compared to patients without hypertension （P〈0.001）. Conclusions Effects of different styles of CHD and different regions of AMI on left ventricular remodeling and cardiac function are different. Myocardial infarction, especially Aa and Aa＋Ai, is one of the most important causes of left ventricular remodeling and cardiac dysfunction. Multiple vessel stenosis and systolic blood pressure at the onset of myocardial infarction reduce LVEF in AMI patients. Antecedent hypertension may accelerate the effect of AMI on cardiac remodeling and dysfunction. Therefore primary and secondary preventions of CHD are critical for protecting heart from remodeling and dysfunction.
文摘Objective: To investigate the relationship between platelet-derived growth factor-A (PDGF-A) and atrial fibrosis in patients who have developed atrial fibrillation (AF) secondary to rheumatic valvular disease. Methods: 84 selected patients participated in the current study who have developed rheumatic heart disease and were going to have a cardiac surgical operation. In the current study, whole subjects were divided into two group, they were atrial fibrillation (AF) group (the quantity is thirty-nine) and sinus rhythm (SR) group (the quantity is forty-five). Before the operation, complete clinical data was available for the whole patients. During the operation, the right atrial tissue (0.3 - 0.5 mm<sup>3</sup>) was disserted from every patient. Right atrial fibrosis was observed by Masson staining and the distribution of PDGF-A in right atrium specimen was observed by immunohistochemistry. RT-PCR techniques were applied to admeasure the mRNA expressions of PDGF-A in patients’ atrial tissue. At the same time, western-Blot techniques were employed to admeasure the protein expressions of PDGF-A. Results: In baseline clinical characteristics, in both AF group and SR group, there was no apparently difference between them (P > 0.05);compared with SR group, the diameters of left atrium and right atrium in AF group were apparently increased (P Conclusion: Atrial remodeling plays an important role in patients with valvular atrial fibrillation;PDGF-A in patients with AF was highly expressed in the right atrial, and was closely related with atrial fibrosis.
