Based on the investigation in Longxi Mountain National Nature Reserve and the theory of survival analysis,a static life table of Taxus chinensis var. mairei population was worked out,the curves of its survival rate,mo...Based on the investigation in Longxi Mountain National Nature Reserve and the theory of survival analysis,a static life table of Taxus chinensis var. mairei population was worked out,the curves of its survival rate,mortality rate and killing power were drawn,and the population dynamics was analyzed by spectral analysis.The results showed that the survival curve of the population appeared to be a type of Deevey Ⅲ,and the high mortality of seeding was one of the important reasons which caused Taxus chinensis var. mairei to be endangered.The spectral analysis of the population showed that there was a marked periodic regularity in the process of natural regeneration of Taxus chinensis var. mairei .展开更多
Function S-rbugh sets are defined by R-function equivalence class, which have dynamic characteristic. Function S-rough sets have dynamic characteristic, law characteristic and law-hiding characteristic. Function S-rou...Function S-rbugh sets are defined by R-function equivalence class, which have dynamic characteristic. Function S-rough sets have dynamic characteristic, law characteristic and law-hiding characteristic. Function S-rough sets can generate f-hiding law and f-hiding law. By engrafting, crossing, and penetrating between the information security theory and function S-rough sets, the security hiding and the authentication of f-hiding law and f-hiding law are given respectively in this paper. The fusion and share between function S-rough sets and information security theory is a new research direction of the application of information law in information system.展开更多
Objective： To determine the clinical serum levels of carcinoembryonic antigen （CEA） and carbohydrate antigen 19-9 （CA19-9）, individually and in combination, for the diagnosis of 50 healthy subjects and 150 cases ...Objective： To determine the clinical serum levels of carcinoembryonic antigen （CEA） and carbohydrate antigen 19-9 （CA19-9）, individually and in combination, for the diagnosis of 50 healthy subjects and 150 cases of esophageal, gastric, and colon cancers. Methods： The sensitivities of the two markers were compared individually and in combination, with specificity set at 100%. Receiver operating characteristic （ROC） curves were plotted. Results： Serum CEA levels were significantly higher in cancer patients than in the control group. The sensitivity of CEA was determined： in esophageal cancer, sensitivity=28%, negative predictive value （NPV）=61.72%, and AUC=0.742 （SE=0.05）, with a significance level of P〈0.0001; in gastric cancer, sensitivity=30%, NPV=58.82%, and AUC=0.734 （SE=0.0S）, with a significance level of P〈0.0001; in colon cancer, sensitivity=74%, NPV=79.36%, and AUC=0.856 （SE=0.04）, with a significance level of P〈0.0001. The sensitivity of CA19-9 was also evaluated： in esophageal cancer, sensitivity=18%, NPV=54.94%, and AUC=0.573 （SE=0.05）, with a significance level of P=0.2054. In gastric cancer, sensitivity=42%, NPV=63.29%, and AUC=0.679 （SE=0.05）, with a significance level of P〈0.0011. In colon cancer, sensitivity=26%, NPV=57.47%, and AUC=0.S80 （SE=0.05）, with a significance level ofP=0.1670. The following were the sensitivities of CEA/CA19-9 combined： in esophageal cancer, sensitivity=42%, NPV=63.29%, SE=0.078 （95% CI： 0.0159-0.322）; gastric cancer, sensitivity=S8%, NPV=70.42%, SE=0.072 （9$% CI： -0.0866-0.198）; and colon cancer, sensitivity=72%, NPV=78.12%, SE=0.070 （9S% CI： 0.137-0.415）. Conclusion： CEA exhibited the highest sensitivity for colon cancer, and CA19-9 exhibited the highest sensitivity for gastric cancer. Combined analysis indicated an increase in diagnostic sensitivity in esophageal and gastric cancer compared with that in colon cancer.展开更多
AIM: To evaluate the nature of the 'learning curve' for laparoscopy-assisted distal gastrectomy (LADG) with systemic lymphadenectomy for early gastric cancer. METHODS: The data of 90 consecutive patients with ...AIM: To evaluate the nature of the 'learning curve' for laparoscopy-assisted distal gastrectomy (LADG) with systemic lymphadenectomy for early gastric cancer. METHODS: The data of 90 consecutive patients with early gastric cancer who underwent LADG with systemic lymphadenectomy between April 2003 and November 2004 were reviewed. The 90 patients were divided into 9 sequential groups of 10 cases in each group and the average operative time of these 9 groups were determined. Other learning indicators, such as transfusion requirements, conversion rates to open surgery, postoperative complication, time to first flatus, and postoperative hospital stay, were evaluated. RESULTS: After the first 10 LADGs, the operative time reached its first plateau (230-240 min/operation) and then reached a second plateau (＜200 min/operation) for the final 30 cases. Although a significant improvement in the operative time was noted after the first 50 cases, there were no significant differences in transfusion requirements, conversion rates to open surgery, postoperative complications, time to first flatus, or postoperative hospital stay between the groups. CONCLUSION: Based on operative time analysis, this study show that experience of 50 cases of LADG with systemic lymphadenectomy for early gastric cancer is required to achieve optimum proficiency.展开更多
In this paper, based on the idea of profit and loss modification, we presentthe iterative non-uniform B-spline curve and surface to settle a key problem in computeraided geometric design and reverse engineering, that ...In this paper, based on the idea of profit and loss modification, we presentthe iterative non-uniform B-spline curve and surface to settle a key problem in computeraided geometric design and reverse engineering, that is, constructing the curve (surface)fitting (interpolating) a given ordered point set without solving a linear system. We startwith a piece of initial non-uniform B-spline curve (surface) which takes the given point setas its control point set. Then by adjusting its control points gradually with iterative formula,we can get a group of non-uniform B-spline curves (surfaces) with gradually higherprecision. In this paper, using modern matrix theory, we strictly prove that the limit curve(surface) of the iteration interpolates the given point set. The non-uniform B-spline curves(surfaces) generated with the iteration have many advantages, such as satisfying theNURBS standard, having explicit expression, gaining locality, and convexity preserving,etc展开更多
We investigated the combined influence of joint inclination angle and joint continuity factor on deforma- tion behavior of jointed rock mass for gypsum specimens with a set of non-persistent open flaws in uni- axial c...We investigated the combined influence of joint inclination angle and joint continuity factor on deforma- tion behavior of jointed rock mass for gypsum specimens with a set of non-persistent open flaws in uni- axial compression. Complete axial stress-strain curves were classified into four types, i.e., single peak, softening after multi-peak yield platform, hardening after multi-peak yield platform and multi-peak dur- ing softening. Observation of crack evolution on the specimen surface reveals that the deformation behavior is correlated to the closure of pre-existing joint, development of fractures in rock matrix and teeth shearing of the shear plane. To investigate the brittleness of the specimens, the ratio of the residual strength to the maximum peak strength as well as the first and last peak strains were studied. At the same joint inclination angle, the ratios between residual strength and the maximum peak strength and the last peak strains increased while the first peak strain decreased with the increase of joint continuity factor. At the same joint continuity factor, the curves of the three brittleness parameters vs. joint inclina- tion angle can either be concave or convex single-oeak or wave-shaoed.展开更多
Aims In ecology and conservation biology,the number of species counted in a biodiversity study is a key metric but is usually a biased underestimate of total species richness because many rare species are not detected...Aims In ecology and conservation biology,the number of species counted in a biodiversity study is a key metric but is usually a biased underestimate of total species richness because many rare species are not detected.Moreover,comparing species richness among sites or samples is a statistical challenge because the observed number of species is sensitive to the number of individuals counted or the area sampled.For individual-based data,we treat a single,empirical sample of species abundances from an investigator-defined species assemblage or community as a reference point for two estimation objectives under two sampling models:estimating the expected number of species(and its unconditional variance)in a random sample of(i)a smaller number of individuals(multinomial model)or a smaller area sampled(Poisson model)and(ii)a larger number of individuals or a larger area sampled.For sample-based incidence(presence–absence)data,under a Bernoulli product model,we treat a single set of species incidence frequencies as the reference point to estimate richness for smaller and larger numbers of sampling units.Methods The first objective is a problem in interpolation that we address with classical rarefaction(multinomial model)and Coleman rarefaction(Poisson model)for individual-based data and with sample-based rarefaction(Bernoulli product model)for incidence frequencies.The second is a problem in extrapolation that we address with sampling-theoretic predictors for the number of species in a larger sample(multinomial model),a larger area(Poisson model)or a larger number of sampling units(Bernoulli product model),based on an estimate of asymptotic species richness.Although published methods exist for many of these objectives,we bring them together here with some new estimators under a unified statistical and notational framework.This novel integration of mathematically distinct approaches allowed us to link interpolated(rarefaction)curves and extrapolated curves to plot a unified species accumulation curve for empirical examp展开更多
Understanding the relationship between landscape pattems and ecological processes has been a central yet challenging research theme in landscape ecology. Over the past decades, many landscape metrics have been propose...Understanding the relationship between landscape pattems and ecological processes has been a central yet challenging research theme in landscape ecology. Over the past decades, many landscape metrics have been proposed but few directly incorporated ecological processes. In this paper, we developed a landscape index, namely, location-weighted landscape index （LWLI） to highlight the role of landscape type in ecological processes, such as nutrient losses and soil erosion. Within the framework of the Lorenz curve theory, we develop this index by integrating land- scape pattern and point-based measurements at a watershed scale. The index can be used to characterize the contribution of landscape pattern to ecological processes （e.g. nutrient losses） with respect to a specific monitoring point in a watershed. Through a case study on nutrient losses in an agricultural area in northeastern China, we found that nutrient losses tended to be higher for a watershed with a higher LWLI value, and vice versa. It implied that LWLI can be used to evaluate the potential risk of nutrient losses or soil erosion by comparing their values across watersheds. In addition, this index can be extended to characterize ecological processes, such as the effect of landscape pattern on wildlife inhabitation and urban heat island effect. Finally, we discuss several problems that should be paid attention to when applying this index to a heterogeneous landscape site.展开更多
Many empirical models have been developed to describe the soil water retention curve (SWRC). In this study, a fractal model for SWRC was derived with a specially constructed Menger sponge to describe the fractal scali...Many empirical models have been developed to describe the soil water retention curve (SWRC). In this study, a fractal model for SWRC was derived with a specially constructed Menger sponge to describe the fractal scaling behavior of soil; relationships were established among the fractal dimension of SWRC, the fractal dimension of soil mass, and soil texture; and the model was used to estimate SWRC with the estimated results being compared to experimental data for verification. The derived fractal model was in a power-law form, similar to the Brooks-Corey and Campbell empirical functions. Experimental data of particle size distribution (PSD), texture, and soil water retention for 10 soils collected at different places in China were used to estimate the fractal dimension of SWRC and the mass fractal dimension. The fractal dimension of SWRC and the mass fractal dimension were linearly related. Also, both of the fractal dimensions were dependent on soil texture, i.e., clay and sand contents. Expressions were proposed to quantify the relationships. Based on the relationships, four methods were used to determine the fractal dimension of SWRC and the model was applied to estimate soil water content at a wide range of tension values. The estimated results compared well with the measured data having relative errors less than 10% for over 60% of the measurements. Thus, this model, estimating the fractal dimension using soil textural data, offered an alternative for predicting SWRC.展开更多
文摘Based on the investigation in Longxi Mountain National Nature Reserve and the theory of survival analysis,a static life table of Taxus chinensis var. mairei population was worked out,the curves of its survival rate,mortality rate and killing power were drawn,and the population dynamics was analyzed by spectral analysis.The results showed that the survival curve of the population appeared to be a type of Deevey Ⅲ,and the high mortality of seeding was one of the important reasons which caused Taxus chinensis var. mairei to be endangered.The spectral analysis of the population showed that there was a marked periodic regularity in the process of natural regeneration of Taxus chinensis var. mairei .
基金the National Natural Science Foundation of China (Grant No.10771073)the Natural Science Foundation of Shandong Province (Grant No.Y2004A04)
文摘Function S-rbugh sets are defined by R-function equivalence class, which have dynamic characteristic. Function S-rough sets have dynamic characteristic, law characteristic and law-hiding characteristic. Function S-rough sets can generate f-hiding law and f-hiding law. By engrafting, crossing, and penetrating between the information security theory and function S-rough sets, the security hiding and the authentication of f-hiding law and f-hiding law are given respectively in this paper. The fusion and share between function S-rough sets and information security theory is a new research direction of the application of information law in information system.
基金the financial support provided by the Biotechnology Information Service–Sub-Distributed Information Centre(supported by the Department of Biotechnology,Government of India)Advanced Bioinformatics Centre(supported by the Government of Rajasthan)at Birla Institute of Scientific Research for the infrastructure and facilities for conducting statistical work
文摘Objective： To determine the clinical serum levels of carcinoembryonic antigen （CEA） and carbohydrate antigen 19-9 （CA19-9）, individually and in combination, for the diagnosis of 50 healthy subjects and 150 cases of esophageal, gastric, and colon cancers. Methods： The sensitivities of the two markers were compared individually and in combination, with specificity set at 100%. Receiver operating characteristic （ROC） curves were plotted. Results： Serum CEA levels were significantly higher in cancer patients than in the control group. The sensitivity of CEA was determined： in esophageal cancer, sensitivity=28%, negative predictive value （NPV）=61.72%, and AUC=0.742 （SE=0.05）, with a significance level of P〈0.0001; in gastric cancer, sensitivity=30%, NPV=58.82%, and AUC=0.734 （SE=0.0S）, with a significance level of P〈0.0001; in colon cancer, sensitivity=74%, NPV=79.36%, and AUC=0.856 （SE=0.04）, with a significance level of P〈0.0001. The sensitivity of CA19-9 was also evaluated： in esophageal cancer, sensitivity=18%, NPV=54.94%, and AUC=0.573 （SE=0.05）, with a significance level of P=0.2054. In gastric cancer, sensitivity=42%, NPV=63.29%, and AUC=0.679 （SE=0.05）, with a significance level of P〈0.0011. In colon cancer, sensitivity=26%, NPV=57.47%, and AUC=0.S80 （SE=0.05）, with a significance level ofP=0.1670. The following were the sensitivities of CEA/CA19-9 combined： in esophageal cancer, sensitivity=42%, NPV=63.29%, SE=0.078 （95% CI： 0.0159-0.322）; gastric cancer, sensitivity=S8%, NPV=70.42%, SE=0.072 （9$% CI： -0.0866-0.198）; and colon cancer, sensitivity=72%, NPV=78.12%, SE=0.070 （9S% CI： 0.137-0.415）. Conclusion： CEA exhibited the highest sensitivity for colon cancer, and CA19-9 exhibited the highest sensitivity for gastric cancer. Combined analysis indicated an increase in diagnostic sensitivity in esophageal and gastric cancer compared with that in colon cancer.
文摘AIM: To evaluate the nature of the 'learning curve' for laparoscopy-assisted distal gastrectomy (LADG) with systemic lymphadenectomy for early gastric cancer. METHODS: The data of 90 consecutive patients with early gastric cancer who underwent LADG with systemic lymphadenectomy between April 2003 and November 2004 were reviewed. The 90 patients were divided into 9 sequential groups of 10 cases in each group and the average operative time of these 9 groups were determined. Other learning indicators, such as transfusion requirements, conversion rates to open surgery, postoperative complication, time to first flatus, and postoperative hospital stay, were evaluated. RESULTS: After the first 10 LADGs, the operative time reached its first plateau (230-240 min/operation) and then reached a second plateau (＜200 min/operation) for the final 30 cases. Although a significant improvement in the operative time was noted after the first 50 cases, there were no significant differences in transfusion requirements, conversion rates to open surgery, postoperative complications, time to first flatus, or postoperative hospital stay between the groups. CONCLUSION: Based on operative time analysis, this study show that experience of 50 cases of LADG with systemic lymphadenectomy for early gastric cancer is required to achieve optimum proficiency.
文摘In this paper, based on the idea of profit and loss modification, we presentthe iterative non-uniform B-spline curve and surface to settle a key problem in computeraided geometric design and reverse engineering, that is, constructing the curve (surface)fitting (interpolating) a given ordered point set without solving a linear system. We startwith a piece of initial non-uniform B-spline curve (surface) which takes the given point setas its control point set. Then by adjusting its control points gradually with iterative formula,we can get a group of non-uniform B-spline curves (surfaces) with gradually higherprecision. In this paper, using modern matrix theory, we strictly prove that the limit curve(surface) of the iteration interpolates the given point set. The non-uniform B-spline curves(surfaces) generated with the iteration have many advantages, such as satisfying theNURBS standard, having explicit expression, gaining locality, and convexity preserving,etc
基金supported by the National Natural Science Foundation of China (No. 11102224)the Fundamental Research Funds for the Central Universities of China(No. 2009QL05)
文摘We investigated the combined influence of joint inclination angle and joint continuity factor on deforma- tion behavior of jointed rock mass for gypsum specimens with a set of non-persistent open flaws in uni- axial compression. Complete axial stress-strain curves were classified into four types, i.e., single peak, softening after multi-peak yield platform, hardening after multi-peak yield platform and multi-peak dur- ing softening. Observation of crack evolution on the specimen surface reveals that the deformation behavior is correlated to the closure of pre-existing joint, development of fractures in rock matrix and teeth shearing of the shear plane. To investigate the brittleness of the specimens, the ratio of the residual strength to the maximum peak strength as well as the first and last peak strains were studied. At the same joint inclination angle, the ratios between residual strength and the maximum peak strength and the last peak strains increased while the first peak strain decreased with the increase of joint continuity factor. At the same joint continuity factor, the curves of the three brittleness parameters vs. joint inclina- tion angle can either be concave or convex single-oeak or wave-shaoed.
基金US National Science Foundation(DEB 0639979 and DBI 0851245 to R.K.C.DEB-0541936 to N.J.G.+4 种基金DEB-0424767 and DEB-0639393 to R.L.C.DEB-0640015 to J.T.L.)the US Department of Energy(022821 to N.J.G.)the Taiwan National Science Council(97-2118-M007-MY3 to A.C.)and the University of Connecticut Research Foundation(to R.L.C.).
文摘Aims In ecology and conservation biology,the number of species counted in a biodiversity study is a key metric but is usually a biased underestimate of total species richness because many rare species are not detected.Moreover,comparing species richness among sites or samples is a statistical challenge because the observed number of species is sensitive to the number of individuals counted or the area sampled.For individual-based data,we treat a single,empirical sample of species abundances from an investigator-defined species assemblage or community as a reference point for two estimation objectives under two sampling models:estimating the expected number of species(and its unconditional variance)in a random sample of(i)a smaller number of individuals(multinomial model)or a smaller area sampled(Poisson model)and(ii)a larger number of individuals or a larger area sampled.For sample-based incidence(presence–absence)data,under a Bernoulli product model,we treat a single set of species incidence frequencies as the reference point to estimate richness for smaller and larger numbers of sampling units.Methods The first objective is a problem in interpolation that we address with classical rarefaction(multinomial model)and Coleman rarefaction(Poisson model)for individual-based data and with sample-based rarefaction(Bernoulli product model)for incidence frequencies.The second is a problem in extrapolation that we address with sampling-theoretic predictors for the number of species in a larger sample(multinomial model),a larger area(Poisson model)or a larger number of sampling units(Bernoulli product model),based on an estimate of asymptotic species richness.Although published methods exist for many of these objectives,we bring them together here with some new estimators under a unified statistical and notational framework.This novel integration of mathematically distinct approaches allowed us to link interpolated(rarefaction)curves and extrapolated curves to plot a unified species accumulation curve for empirical examp
基金Under the auspices of Chinese Academy of Sciences (No. KZCX2-YW-421)National Natural Science Foundation of China (No. 40621061, 30570319)
文摘Understanding the relationship between landscape pattems and ecological processes has been a central yet challenging research theme in landscape ecology. Over the past decades, many landscape metrics have been proposed but few directly incorporated ecological processes. In this paper, we developed a landscape index, namely, location-weighted landscape index （LWLI） to highlight the role of landscape type in ecological processes, such as nutrient losses and soil erosion. Within the framework of the Lorenz curve theory, we develop this index by integrating land- scape pattern and point-based measurements at a watershed scale. The index can be used to characterize the contribution of landscape pattern to ecological processes （e.g. nutrient losses） with respect to a specific monitoring point in a watershed. Through a case study on nutrient losses in an agricultural area in northeastern China, we found that nutrient losses tended to be higher for a watershed with a higher LWLI value, and vice versa. It implied that LWLI can be used to evaluate the potential risk of nutrient losses or soil erosion by comparing their values across watersheds. In addition, this index can be extended to characterize ecological processes, such as the effect of landscape pattern on wildlife inhabitation and urban heat island effect. Finally, we discuss several problems that should be paid attention to when applying this index to a heterogeneous landscape site.
基金Project supported by the National Natural Science Foundation of China (Nos. 50479011 and 50279025).
文摘Many empirical models have been developed to describe the soil water retention curve (SWRC). In this study, a fractal model for SWRC was derived with a specially constructed Menger sponge to describe the fractal scaling behavior of soil; relationships were established among the fractal dimension of SWRC, the fractal dimension of soil mass, and soil texture; and the model was used to estimate SWRC with the estimated results being compared to experimental data for verification. The derived fractal model was in a power-law form, similar to the Brooks-Corey and Campbell empirical functions. Experimental data of particle size distribution (PSD), texture, and soil water retention for 10 soils collected at different places in China were used to estimate the fractal dimension of SWRC and the mass fractal dimension. The fractal dimension of SWRC and the mass fractal dimension were linearly related. Also, both of the fractal dimensions were dependent on soil texture, i.e., clay and sand contents. Expressions were proposed to quantify the relationships. Based on the relationships, four methods were used to determine the fractal dimension of SWRC and the model was applied to estimate soil water content at a wide range of tension values. The estimated results compared well with the measured data having relative errors less than 10% for over 60% of the measurements. Thus, this model, estimating the fractal dimension using soil textural data, offered an alternative for predicting SWRC.
