The spread and removal of pollution sources,namely,cough-released droplets in three different areas(front,middle,and rear areas)of a fully-loaded passenger car in a high-speed train under different fresh air flow volu...The spread and removal of pollution sources,namely,cough-released droplets in three different areas(front,middle,and rear areas)of a fully-loaded passenger car in a high-speed train under different fresh air flow volume were studied using computational fluid dynamics(CFD)method.In addition,the structure of indoor flow fields was also analysed.The results show that the large eddies are more stable and flow faster in the air supply under Mode 2(fresh air volume:2200m3/h)compared to Mode 1(fresh air volume:1100m3/h).By analysing the spreading process of droplets sprayed at different locations in the passenger car and with different particle sizes,the removal trends for droplets are found to be similar under the two air supply modes.However,when increasing the fresh air flow volume,the droplets in the middle and front areas of the passenger car are removed faster.When the droplets had dispersed for 60s,Mode 2 exhibited a removal rate approximately 1%–3%higher than Mode 1 for small and medium-sized droplets with diameters of 10 and 50μm.While those in the rear area,the situation is reversed,with Mode 1 slightly surpassing Mode 2 by 1%–3%.For large droplets with a diameter of 100μm,both modes achieved a removal rate of over 96%in all three regions at the 60 s.The results can provide guidance for air supply modes of passenger cars of high-speed trains,thus suppressing the spread of virus-carrying droplets and reducing the risk of viral infection among passengers.展开更多
Objective: To detect the expression changes of proton-sensing receptor G protein-coupled receptor 2A (G2A) and ovarian cancer G protein-coupled receptors 1 (OGR1) in human peripheral blood cells of patients with hypox...Objective: To detect the expression changes of proton-sensing receptor G protein-coupled receptor 2A (G2A) and ovarian cancer G protein-coupled receptors 1 (OGR1) in human peripheral blood cells of patients with hypoxia-induced pulmonary hypertension (HPH). Methods: Thirty-one patients with HPH were enrolled for IPH group, 16 males and 15 females, aged (65.19 ± 5.86) years;and 30 healthy people were enrolled for control group (NC group), 15 males and 15 females, aged (63.47 ± 6.16) years. The peripheral blood samples were collected and the mRNA expressions of G2A and OGR1 were determined by using real-time fluorescent quantitative PCR. The pulmonary arterial pressure (PAP) of HPH group was detected with echocardiography for the analysis of blood gas and pulmonary function testing. Human peripheral blood was collected to detect the mRNA levels of G2A, OGR1 and the serum levels of tumor necrosis factor-α (TNF-α). Results: PaCO2 was increased significantly in HPH group than that in NC group (p < .05). The percentage of forced expiratory volume in 1 s in predicted value (FEV1 pro%) and the ratio of FEV1/forced vital capacity (FVC) in HPH group were significant lower than those in NC group (p < .05). The expressions of peripheral blood G2A mRNA and TNF-α in HPH group were increased dramatically than those in NC group (p < .05). The expressions of OGR1 mRNA in peripheral blood had no difference between HPH group and NC group. The expressions of G2A mRNA and TNF-α in HPH group were positively related to pulmonary artery pressure significantly. Conclusions: The expression of proton-sensing receptor G2A and the level of TNF-α were increased in peripheral blood cells of patients with pulmonary hypertension. The expressions of TNF-α and G2A had positive correlations with pulmonary artery pressure.展开更多
Objective:To study the influence of bone marrow mesenchymal stem cells(MSCs)transplantation on hypoxic pulmonary hypertension(HPH)in rats.Methods:MSCs in SD rats were separated,cultivated,identified in vitro,and label...Objective:To study the influence of bone marrow mesenchymal stem cells(MSCs)transplantation on hypoxic pulmonary hypertension(HPH)in rats.Methods:MSCs in SD rats were separated,cultivated,identified in vitro,and labeled by the green fluorescence protein(GFP)adenovirus.Healthy male SD rats were randomly divided into four groups:normal control group(NC group)and HPH group,with eight rats in each group respectively;HPH+mesenchymal stem cell transplantation group(MSCs group)and HPH+vascular endothelial growth factor+mesenchymal stem cell transplantation group(VEGF+MSCs group),with twenty-four rats in each group respectively.In this experiment,intermittent normobaric hypoxia was employed to establish the pulmonary hypertension rat models,with stem cells transfected and transplanted.The mean pulmonary artery pressure(mPAP)was observed in rats to calculate the right ventricular hypertrophy index(RVHI);the morphological changes of pulmonary arterioles in each group of rats were observed under the microscope;the distribution and manifestation of MSCs fluorescently labeled by adenovirus transfection were observed in pulmonary arterioles under the fluorescence microscope at the set time points of 7 d,14 d and 28 d after the transplantation of stem cells.Results:For NC group,the mPAP(mmHg)was 15.5±1.5 at 28 d,while the mPAP in HPH,MSCs and VEGF+MSCs groups were 26.1±1.9,21.6±2.7 and 20.1±2.9 respectively which were apparently higher than that in NC group(p<.01).Compared with HPH group(p<.01),the mPAP was obviously decreased in MSCs and VEGF+MSCs groups.There was no significant difference between MSCs and VEGF+MSCs groups.At 28 d,RVHI for NC group was 0.28±0.02,while the RVHI in HPH,MSCs and VEGF+MSCs groups were 0.43±0.07,0.34±0.03 and 0.35±0.01 respectively which were apparently higher than that in NC group(p<.01).In comparison with HPH group,RVHI was significantly decreased in MSCs and VEGF+MSCs groups(p<.05).There was no significant difference between MSCs and VEGF+MSCs groups.For HPH group,at 28 d,pulmonary arterioles were apparently thickened,with luminal stenosis&obliteration and incomplete endothelial cells.Compared with HPH group,pulmonary arterioles in MSCs group became thinning,with the lumen unobstructed and the integrity of endothelial cells improved.The changes in the manifestation of MSCs and VEGF+MSCs groups were not significant.Conclusions:The transplantation of MSCs can improve the remodeling of pulmonary arterioles to partially reverse the progress of HPH;the combined transplantation of VEGF and MSCs doesn’t improve the effect of MSC transplantation.展开更多
Objective:To observe the presence of toll-like receptor 4(TLR4)gene polymorphism in the venous blood in patients with sepsis,meanwhile,to observe the expression and the diagnostic value of TLR4 mRNA,interferon-(IFN-),...Objective:To observe the presence of toll-like receptor 4(TLR4)gene polymorphism in the venous blood in patients with sepsis,meanwhile,to observe the expression and the diagnostic value of TLR4 mRNA,interferon-(IFN-),interleukin-23(IL-23),procalcitonin(PCT)and C-reactive protein(CRP)in patients with different degrees of sepsis.Methods:The peripheral blood samples from the subjects were collected to extract genomic DNA,gene sequencing and enzyme digestion method were applied to the detection of TLR4 Asp299Gly loci polymorphism.The expression of TLR4 mRNA in the peripheral blood was detected by reverse transcriptase polymerase chain reaction(RT-PCR).The expression levels of IFN-,IL-23,PCT and CRP were measured by enzyme linked immunosorbent assay(ELISA).Results:(1)The gene polymorphism was not present in TLR4 Asp299Gly loci;(2)The expression of TLR4 mRNA in the peripheral blood in patients with sepsis:on d1,there were statistically significant differences between the normal group and the group(APACHE II≤20),between the normal group and the group(APACHE II>20),between the group(APACHE II≤20)and the group(AAPACHE II>20)(t=5.741,14.780 and 10.500,all p<.01).APACHE II stands for Acute Physiology and Chronic Health Evaluation II.On d7,there were statistically significant differences between the normal group and the group(APACHE II≤20),between the normal group and the group(APACHE II>20),between the group(APACHE II≤20)and the group(APACHE II>20)(t=4.186,13.830 and 9.645,all p<.01);(3)The expression levels of IFN-,IL-23,PCT and CRP were obviously upregulated(all p<.01),and TLR4 was positively correlated with IFN-and IL-23(all p<.01);(4)The best cutoff value of TLR4 mRNA at baseline was 891.6μg/L,with a sensitivity of 100%and a diagnostic specificity of 57%.The best cutoff value of IFN-at baseline was 84.5μg/L,with a sensitivity of 100%and a diagnostic specificity of 57%.The best cutoff value of IL-23 at baseline was 861μg/L,with a sensitivity of 100%and a diagnostic specificity of 97%.Conclusions:(1)The Asp299Gly polymorphism is not present in TLR4 gene;(2)The expression levels of TLR4 mRNA,IFN-and IL-23 are relatively high in patients with sepsis,and will be higher with the increased severity of sepsis;(3)TLR4 mRNA,IFN-and IL-23 can be used as molecular biomarkers for the early diagnosis of sepsis.展开更多
Objective:To investigate the change and relativity of noninvasive positive pressure ventilation(NIPPV)on the gene expression of ubiquitin system of skeletal muscle in patient with acute exacerbation of chronic obstruc...Objective:To investigate the change and relativity of noninvasive positive pressure ventilation(NIPPV)on the gene expression of ubiquitin system of skeletal muscle in patient with acute exacerbation of chronic obstructive pulmonary disease(AECOPD).Methods:80 patients with AECOPD were divided into two groups based on whether the NIPPV treatment was given or not,38 cases in the study group and 42 in the control group.The blood gas analysis and pulmonary function were monitored and recorded before and 14 days after treatment.A skeletal muscle biopsy was performed 14 days after therapy.The mRNA expression of ribosomal protein S21(RPS21)and ubiquitin in skeletal muscle cell were measured by RT-PCR.Results:After 14 days treatment,the levels of PaCO_(2),PaO_(2),PH and FEV_(1)% in the NIPPV group improved much better than in the control group(p<.05).The gene expression of RPS21 and ubiquitin was obviously lower in the study group than in the control group(p<.05).The level of RPS21 was negatively related with PaO_(2),PH and FEV1%,and the level of ubiquitin was negatively related with PaO_(2) and FEV1%,but positively correlated with PaCO_(2).The area under the ROC curves of RPS21,ubiquitin,PaCO_(2) and FEV_(1)% were 0.771,0.885,0.821 and 0.734 respectively in the study group.The cut-off points were 103.978,8.128,45.350 and 51.350 respectively.The sensitivity evaluation of acid poisoning was 90.9%,and the specificities for each were 75%,75%,50% and 50%.Conclusions:NIPPV is effective for AECOPD patients through the gene expression of ubiquitin system of skeletal muscle.展开更多
Objective:To explore the relationship between the expression of TLR4 and TIRAP and sepsis severity.Methods:The study selected 30 healthy examinees as the control group and 53 patients with sepsis as the observation gr...Objective:To explore the relationship between the expression of TLR4 and TIRAP and sepsis severity.Methods:The study selected 30 healthy examinees as the control group and 53 patients with sepsis as the observation group.The patients in the observation group were assessed by Acute Physiology and Chronic Health Evaluation Ⅱ(APACHE Ⅱ).40 patients with APACHE Ⅱ score≤20,were classified into the low-score sepsis group;13 patients with APACHE Ⅱ score>20,were classified into the high-score sepsis group.The levels of TLR4 and TIRAP in venous serum were detected in all subjects by enzyme-linked immunosorbent assay(ELISA).Results:The levels of TLR4 and TIRAP in serum were 0.886±0.058 ng/ml and 5.216±0.410 ng/ml in the control group;2.253±0.379 ng/ml and 9.540±2.294 ng/ml in the low-score sepsis group;4.494±0.709 ng/ml and 19.206±1.755 ng/ml in the high-score sepsis group.The observation group(low-score and high-score sepsis groups)was significantly different from the control group(p=.000),and the low-score sepsis group was significantly different from the high-score sepsis group(p=.000).With APACHE II score of 20 as the cut-off point,the low-score sepsis group was consisted of low-risk patients and the high-score group was consisted of the high-risk,which can indicate the sepsis severity.According to Pearson’s correlation analysis,the level of TLR4 was positively correlated with sepsis severity(r=0.931,p<.05),the level of TIRAP was also positively correlated with the sepsis severity(r=0.972,p<.05);the level of TLR4 was positively correlated with the level of TIRAP(r=0.936,p<.05).Conclusions:The levels of TLR4 and TIRAP in septic patients can be used to predict and determine the severity of sepsis.展开更多
The application of biochar to soil is widely recognized as a promising strategy for enhancing the accumulation and stability of soil organic carbon(SOC),which is crucial in mitigating climate change.However,the influe...The application of biochar to soil is widely recognized as a promising strategy for enhancing the accumulation and stability of soil organic carbon(SOC),which is crucial in mitigating climate change.However,the influence of interactions between plants and biochar on soil microbial communities and their involvement in SOC mineralization and stability remains unclear.This understanding is essential for optimizing carbon(C)sequestration in systems involving plants,soil,and biochar.In this study,employing a 13C natural abundance approach,we investigated the effect of biochar on the maize rhizosphere priming effect(RPE)in paddy soil.We also examined alterations in microbial communities and functional genes related to C degradation and fixation.Over the 99 days of maize growth,biochar application increased RPE and total SOC while decreasing dissolved organic C.It also elevated soil pH,resulting in shifts in fungal and bacterial community structure,favoring oligotrophic species.Fungal and bacterial assemblies were dominated by deterministic and stochastic processes,respectively.While the abundance of fungal guilds varied irregularly,bacterial guilds were uniformly enriched under biochar-plant interactions.Functional traits such as ecoenzymatic activities,bacterial guilds,and functional genes predominantly affected RPE under biochar application.Bacterial functional genes associated with C degradation and fixation were concurrently enhanced with biochar application.Our results indicate that interactions between plants and biochar can enhance native SOC mineralization and accumulation in a short timeframe by modulating functional traits of soil microorganisms,particularly the bacterial community involved in C degradation and fixation.展开更多
The Markov chain is well studied and widely applied in many areas.For some Markov chains,it is infeasible to obtain the explicit expressions of their corresponding finite-dimensional distributions and sometimes it is ...The Markov chain is well studied and widely applied in many areas.For some Markov chains,it is infeasible to obtain the explicit expressions of their corresponding finite-dimensional distributions and sometimes it is time-consuming for computation.In this paper,we propose an approximation method for Markov chains by applying the copula theory.For this purpose,we first discuss the checkerboard copula-based Markov chain,which is the Markov chain generated by the family of checkerboard copulas.This Markov chain has some appealing properties,such as self-similarity in copulas and having explicit forms of finite-dimensional distributions.Then we prove that each Markov chain can be approximated by a sequence of checkerboard copula-based Markov chains,and the error bounds of the approximate distributions are provided.Employing the checkerboard copula-based approximation method,we propose a sufficient condition for the geometric β-mixing of copula-based Markov chains.This condition allows copulas of Markov chains to be asymmetric.Finally,by applying the approximation method,analytical recurrence formulas are also derived for computing approximate distributions of both the first passage time and the occupation time of a Markov chain,and numerical results are listed to show the approximation errors.展开更多
Copula method has been widely applied to model the correlation among underlying assets in financial market. In this paper, we propose to use the multivariate Frechet copula family presented in J. P. Yang et al. [Insur...Copula method has been widely applied to model the correlation among underlying assets in financial market. In this paper, we propose to use the multivariate Frechet copula family presented in J. P. Yang et al. [Insurance Math. Econom., 2009, 45：139 147] to price multivariate financial instruments whose payoffs depend on the k^th realization of the underlying assets and collateralized debt obligation （CDO）. The advantage of the multivariate Frechet copula is discussed. Empirical study shows that such copula family gives a better fitting to CDO＇s market price than Gaussian copula for some derivatives.展开更多
This paper discusses the correlation structure between London Interbank Offered Rates （LIBOR） by using the copula function. We start from one simplified model of A. Brace, D. Gatarek, and M. Musiela （1997） and fin...This paper discusses the correlation structure between London Interbank Offered Rates （LIBOR） by using the copula function. We start from one simplified model of A. Brace, D. Gatarek, and M. Musiela （1997） and find out that the copula function between two LIBOR rates can be expressed as a sum of an infinite series, where the main term is a distribution function with Gaussian copula. Partial differential equation method is used for deriving the copula expansion. Numerical results show that the copula of the LIBOR rates and Gaussian copula are very close in the central region and differ in the tail, and the Gaussian copula approximation to the copula function between the LIBOR rates provides satisfying results in the normal situation.展开更多
In actuarial science, Panjer recursion （1981） is used in insurance to compute the loss distribution of the compound risk models. When the severity distribution is continuous with density function, numerical calculat...In actuarial science, Panjer recursion （1981） is used in insurance to compute the loss distribution of the compound risk models. When the severity distribution is continuous with density function, numerical calculation for the compound distribution by applying Panjer recursion will involve an approxi- mation of the integration. In order to simplify the numerical algorithms, we apply Bernstein approximation for the continuous severity distribution function and obtain approximated recursive equations, which are used for computing the approximated values of the compound distribution. The theoretical error bound for the approximation is also obtained. Numerical results show that our algorithm provides reliable results.展开更多
基金the National Natural Science Foundation of China(Grant Number 52078199)the China National Railway Group Limited(Grant Number P2021J036)+1 种基金the Hunan Young Talents Program(Grant Number 2020RC3019)the Young Elite Scientists Sponsorship Program by CAST(2020QNRC001).
文摘The spread and removal of pollution sources,namely,cough-released droplets in three different areas(front,middle,and rear areas)of a fully-loaded passenger car in a high-speed train under different fresh air flow volume were studied using computational fluid dynamics(CFD)method.In addition,the structure of indoor flow fields was also analysed.The results show that the large eddies are more stable and flow faster in the air supply under Mode 2(fresh air volume:2200m3/h)compared to Mode 1(fresh air volume:1100m3/h).By analysing the spreading process of droplets sprayed at different locations in the passenger car and with different particle sizes,the removal trends for droplets are found to be similar under the two air supply modes.However,when increasing the fresh air flow volume,the droplets in the middle and front areas of the passenger car are removed faster.When the droplets had dispersed for 60s,Mode 2 exhibited a removal rate approximately 1%–3%higher than Mode 1 for small and medium-sized droplets with diameters of 10 and 50μm.While those in the rear area,the situation is reversed,with Mode 1 slightly surpassing Mode 2 by 1%–3%.For large droplets with a diameter of 100μm,both modes achieved a removal rate of over 96%in all three regions at the 60 s.The results can provide guidance for air supply modes of passenger cars of high-speed trains,thus suppressing the spread of virus-carrying droplets and reducing the risk of viral infection among passengers.
文摘Objective: To detect the expression changes of proton-sensing receptor G protein-coupled receptor 2A (G2A) and ovarian cancer G protein-coupled receptors 1 (OGR1) in human peripheral blood cells of patients with hypoxia-induced pulmonary hypertension (HPH). Methods: Thirty-one patients with HPH were enrolled for IPH group, 16 males and 15 females, aged (65.19 ± 5.86) years;and 30 healthy people were enrolled for control group (NC group), 15 males and 15 females, aged (63.47 ± 6.16) years. The peripheral blood samples were collected and the mRNA expressions of G2A and OGR1 were determined by using real-time fluorescent quantitative PCR. The pulmonary arterial pressure (PAP) of HPH group was detected with echocardiography for the analysis of blood gas and pulmonary function testing. Human peripheral blood was collected to detect the mRNA levels of G2A, OGR1 and the serum levels of tumor necrosis factor-α (TNF-α). Results: PaCO2 was increased significantly in HPH group than that in NC group (p < .05). The percentage of forced expiratory volume in 1 s in predicted value (FEV1 pro%) and the ratio of FEV1/forced vital capacity (FVC) in HPH group were significant lower than those in NC group (p < .05). The expressions of peripheral blood G2A mRNA and TNF-α in HPH group were increased dramatically than those in NC group (p < .05). The expressions of OGR1 mRNA in peripheral blood had no difference between HPH group and NC group. The expressions of G2A mRNA and TNF-α in HPH group were positively related to pulmonary artery pressure significantly. Conclusions: The expression of proton-sensing receptor G2A and the level of TNF-α were increased in peripheral blood cells of patients with pulmonary hypertension. The expressions of TNF-α and G2A had positive correlations with pulmonary artery pressure.
文摘Objective:To study the influence of bone marrow mesenchymal stem cells(MSCs)transplantation on hypoxic pulmonary hypertension(HPH)in rats.Methods:MSCs in SD rats were separated,cultivated,identified in vitro,and labeled by the green fluorescence protein(GFP)adenovirus.Healthy male SD rats were randomly divided into four groups:normal control group(NC group)and HPH group,with eight rats in each group respectively;HPH+mesenchymal stem cell transplantation group(MSCs group)and HPH+vascular endothelial growth factor+mesenchymal stem cell transplantation group(VEGF+MSCs group),with twenty-four rats in each group respectively.In this experiment,intermittent normobaric hypoxia was employed to establish the pulmonary hypertension rat models,with stem cells transfected and transplanted.The mean pulmonary artery pressure(mPAP)was observed in rats to calculate the right ventricular hypertrophy index(RVHI);the morphological changes of pulmonary arterioles in each group of rats were observed under the microscope;the distribution and manifestation of MSCs fluorescently labeled by adenovirus transfection were observed in pulmonary arterioles under the fluorescence microscope at the set time points of 7 d,14 d and 28 d after the transplantation of stem cells.Results:For NC group,the mPAP(mmHg)was 15.5±1.5 at 28 d,while the mPAP in HPH,MSCs and VEGF+MSCs groups were 26.1±1.9,21.6±2.7 and 20.1±2.9 respectively which were apparently higher than that in NC group(p<.01).Compared with HPH group(p<.01),the mPAP was obviously decreased in MSCs and VEGF+MSCs groups.There was no significant difference between MSCs and VEGF+MSCs groups.At 28 d,RVHI for NC group was 0.28±0.02,while the RVHI in HPH,MSCs and VEGF+MSCs groups were 0.43±0.07,0.34±0.03 and 0.35±0.01 respectively which were apparently higher than that in NC group(p<.01).In comparison with HPH group,RVHI was significantly decreased in MSCs and VEGF+MSCs groups(p<.05).There was no significant difference between MSCs and VEGF+MSCs groups.For HPH group,at 28 d,pulmonary arterioles were apparently thickened,with luminal stenosis&obliteration and incomplete endothelial cells.Compared with HPH group,pulmonary arterioles in MSCs group became thinning,with the lumen unobstructed and the integrity of endothelial cells improved.The changes in the manifestation of MSCs and VEGF+MSCs groups were not significant.Conclusions:The transplantation of MSCs can improve the remodeling of pulmonary arterioles to partially reverse the progress of HPH;the combined transplantation of VEGF and MSCs doesn’t improve the effect of MSC transplantation.
文摘Objective:To observe the presence of toll-like receptor 4(TLR4)gene polymorphism in the venous blood in patients with sepsis,meanwhile,to observe the expression and the diagnostic value of TLR4 mRNA,interferon-(IFN-),interleukin-23(IL-23),procalcitonin(PCT)and C-reactive protein(CRP)in patients with different degrees of sepsis.Methods:The peripheral blood samples from the subjects were collected to extract genomic DNA,gene sequencing and enzyme digestion method were applied to the detection of TLR4 Asp299Gly loci polymorphism.The expression of TLR4 mRNA in the peripheral blood was detected by reverse transcriptase polymerase chain reaction(RT-PCR).The expression levels of IFN-,IL-23,PCT and CRP were measured by enzyme linked immunosorbent assay(ELISA).Results:(1)The gene polymorphism was not present in TLR4 Asp299Gly loci;(2)The expression of TLR4 mRNA in the peripheral blood in patients with sepsis:on d1,there were statistically significant differences between the normal group and the group(APACHE II≤20),between the normal group and the group(APACHE II>20),between the group(APACHE II≤20)and the group(AAPACHE II>20)(t=5.741,14.780 and 10.500,all p<.01).APACHE II stands for Acute Physiology and Chronic Health Evaluation II.On d7,there were statistically significant differences between the normal group and the group(APACHE II≤20),between the normal group and the group(APACHE II>20),between the group(APACHE II≤20)and the group(APACHE II>20)(t=4.186,13.830 and 9.645,all p<.01);(3)The expression levels of IFN-,IL-23,PCT and CRP were obviously upregulated(all p<.01),and TLR4 was positively correlated with IFN-and IL-23(all p<.01);(4)The best cutoff value of TLR4 mRNA at baseline was 891.6μg/L,with a sensitivity of 100%and a diagnostic specificity of 57%.The best cutoff value of IFN-at baseline was 84.5μg/L,with a sensitivity of 100%and a diagnostic specificity of 57%.The best cutoff value of IL-23 at baseline was 861μg/L,with a sensitivity of 100%and a diagnostic specificity of 97%.Conclusions:(1)The Asp299Gly polymorphism is not present in TLR4 gene;(2)The expression levels of TLR4 mRNA,IFN-and IL-23 are relatively high in patients with sepsis,and will be higher with the increased severity of sepsis;(3)TLR4 mRNA,IFN-and IL-23 can be used as molecular biomarkers for the early diagnosis of sepsis.
文摘Objective:To investigate the change and relativity of noninvasive positive pressure ventilation(NIPPV)on the gene expression of ubiquitin system of skeletal muscle in patient with acute exacerbation of chronic obstructive pulmonary disease(AECOPD).Methods:80 patients with AECOPD were divided into two groups based on whether the NIPPV treatment was given or not,38 cases in the study group and 42 in the control group.The blood gas analysis and pulmonary function were monitored and recorded before and 14 days after treatment.A skeletal muscle biopsy was performed 14 days after therapy.The mRNA expression of ribosomal protein S21(RPS21)and ubiquitin in skeletal muscle cell were measured by RT-PCR.Results:After 14 days treatment,the levels of PaCO_(2),PaO_(2),PH and FEV_(1)% in the NIPPV group improved much better than in the control group(p<.05).The gene expression of RPS21 and ubiquitin was obviously lower in the study group than in the control group(p<.05).The level of RPS21 was negatively related with PaO_(2),PH and FEV1%,and the level of ubiquitin was negatively related with PaO_(2) and FEV1%,but positively correlated with PaCO_(2).The area under the ROC curves of RPS21,ubiquitin,PaCO_(2) and FEV_(1)% were 0.771,0.885,0.821 and 0.734 respectively in the study group.The cut-off points were 103.978,8.128,45.350 and 51.350 respectively.The sensitivity evaluation of acid poisoning was 90.9%,and the specificities for each were 75%,75%,50% and 50%.Conclusions:NIPPV is effective for AECOPD patients through the gene expression of ubiquitin system of skeletal muscle.
文摘Objective:To explore the relationship between the expression of TLR4 and TIRAP and sepsis severity.Methods:The study selected 30 healthy examinees as the control group and 53 patients with sepsis as the observation group.The patients in the observation group were assessed by Acute Physiology and Chronic Health Evaluation Ⅱ(APACHE Ⅱ).40 patients with APACHE Ⅱ score≤20,were classified into the low-score sepsis group;13 patients with APACHE Ⅱ score>20,were classified into the high-score sepsis group.The levels of TLR4 and TIRAP in venous serum were detected in all subjects by enzyme-linked immunosorbent assay(ELISA).Results:The levels of TLR4 and TIRAP in serum were 0.886±0.058 ng/ml and 5.216±0.410 ng/ml in the control group;2.253±0.379 ng/ml and 9.540±2.294 ng/ml in the low-score sepsis group;4.494±0.709 ng/ml and 19.206±1.755 ng/ml in the high-score sepsis group.The observation group(low-score and high-score sepsis groups)was significantly different from the control group(p=.000),and the low-score sepsis group was significantly different from the high-score sepsis group(p=.000).With APACHE II score of 20 as the cut-off point,the low-score sepsis group was consisted of low-risk patients and the high-score group was consisted of the high-risk,which can indicate the sepsis severity.According to Pearson’s correlation analysis,the level of TLR4 was positively correlated with sepsis severity(r=0.931,p<.05),the level of TIRAP was also positively correlated with the sepsis severity(r=0.972,p<.05);the level of TLR4 was positively correlated with the level of TIRAP(r=0.936,p<.05).Conclusions:The levels of TLR4 and TIRAP in septic patients can be used to predict and determine the severity of sepsis.
基金supported by the National Natural Science Foundation of China(No.31870419)the National Key Research and Development Program of China(No.2016YFD0300203-4).
文摘The application of biochar to soil is widely recognized as a promising strategy for enhancing the accumulation and stability of soil organic carbon(SOC),which is crucial in mitigating climate change.However,the influence of interactions between plants and biochar on soil microbial communities and their involvement in SOC mineralization and stability remains unclear.This understanding is essential for optimizing carbon(C)sequestration in systems involving plants,soil,and biochar.In this study,employing a 13C natural abundance approach,we investigated the effect of biochar on the maize rhizosphere priming effect(RPE)in paddy soil.We also examined alterations in microbial communities and functional genes related to C degradation and fixation.Over the 99 days of maize growth,biochar application increased RPE and total SOC while decreasing dissolved organic C.It also elevated soil pH,resulting in shifts in fungal and bacterial community structure,favoring oligotrophic species.Fungal and bacterial assemblies were dominated by deterministic and stochastic processes,respectively.While the abundance of fungal guilds varied irregularly,bacterial guilds were uniformly enriched under biochar-plant interactions.Functional traits such as ecoenzymatic activities,bacterial guilds,and functional genes predominantly affected RPE under biochar application.Bacterial functional genes associated with C degradation and fixation were concurrently enhanced with biochar application.Our results indicate that interactions between plants and biochar can enhance native SOC mineralization and accumulation in a short timeframe by modulating functional traits of soil microorganisms,particularly the bacterial community involved in C degradation and fixation.
基金supported by the National Key R&D Program of China(Grant No.2018YFA0703900)National Natural Science Foundation of China(Grant No.11671021)+1 种基金supported by National Natural Science Foundation of China(Grant Nos.11761051and 11561047)the Natural Science Foundation of Jiangxi Province(Grant Nos.20181BAB211003 and 20192BAB211006)。
文摘The Markov chain is well studied and widely applied in many areas.For some Markov chains,it is infeasible to obtain the explicit expressions of their corresponding finite-dimensional distributions and sometimes it is time-consuming for computation.In this paper,we propose an approximation method for Markov chains by applying the copula theory.For this purpose,we first discuss the checkerboard copula-based Markov chain,which is the Markov chain generated by the family of checkerboard copulas.This Markov chain has some appealing properties,such as self-similarity in copulas and having explicit forms of finite-dimensional distributions.Then we prove that each Markov chain can be approximated by a sequence of checkerboard copula-based Markov chains,and the error bounds of the approximate distributions are provided.Employing the checkerboard copula-based approximation method,we propose a sufficient condition for the geometric β-mixing of copula-based Markov chains.This condition allows copulas of Markov chains to be asymmetric.Finally,by applying the approximation method,analytical recurrence formulas are also derived for computing approximate distributions of both the first passage time and the occupation time of a Markov chain,and numerical results are listed to show the approximation errors.
文摘Copula method has been widely applied to model the correlation among underlying assets in financial market. In this paper, we propose to use the multivariate Frechet copula family presented in J. P. Yang et al. [Insurance Math. Econom., 2009, 45：139 147] to price multivariate financial instruments whose payoffs depend on the k^th realization of the underlying assets and collateralized debt obligation （CDO）. The advantage of the multivariate Frechet copula is discussed. Empirical study shows that such copula family gives a better fitting to CDO＇s market price than Gaussian copula for some derivatives.
基金The authors thank the referees for their valuable comments. Yang＇s research was partly supported by the Key Program of National Natural Science Foundation of China （Grant No. 11131002） and the National Natural Science Foundation of China （Grants No. 11271033）. Zheng＇s research was supported by the Ng-Jhit-Cheong Foundation.
文摘This paper discusses the correlation structure between London Interbank Offered Rates （LIBOR） by using the copula function. We start from one simplified model of A. Brace, D. Gatarek, and M. Musiela （1997） and find out that the copula function between two LIBOR rates can be expressed as a sum of an infinite series, where the main term is a distribution function with Gaussian copula. Partial differential equation method is used for deriving the copula expansion. Numerical results show that the copula of the LIBOR rates and Gaussian copula are very close in the central region and differ in the tail, and the Gaussian copula approximation to the copula function between the LIBOR rates provides satisfying results in the normal situation.
文摘In actuarial science, Panjer recursion （1981） is used in insurance to compute the loss distribution of the compound risk models. When the severity distribution is continuous with density function, numerical calculation for the compound distribution by applying Panjer recursion will involve an approxi- mation of the integration. In order to simplify the numerical algorithms, we apply Bernstein approximation for the continuous severity distribution function and obtain approximated recursive equations, which are used for computing the approximated values of the compound distribution. The theoretical error bound for the approximation is also obtained. Numerical results show that our algorithm provides reliable results.
