老龄多人口死亡率联合建模与一致性预测

退休年龄以上的老年人群死亡率预测是养老金精算和长寿风险度量的基础。针对我国大陆地区退休年龄以上人群死亡率数据量较小且波动较大的问题,借助多人口联合建模思想,基于单人口CBD模型,提出了一个适用于老龄死亡率建模的Logistic多人口模型。通过加入更多相关人口数据信息来预测我国老年人口死亡率,选取我国台湾地区分性别死亡率相关数据,与我国大陆地区分性别死亡率数据进行联合建模。研究发现,Logistic多人口死亡率模型比单人口CBD模型表现出更好的拟合效果和长期预测一致性效果。

多人口随机死亡率模型研究:理论方法与进展综述

多人口随机死亡率模型是人口统计学与保险精算学的交叉研究领域,是国内外学者高度关注的前沿问题。通过梳理国内外多人口随机死亡率模型研究的重点文献,根据研究方法的不同,寻迹多人口死亡率模型的发展脉络,将已有研究归纳为三大类:多人口参数随机死亡率模型、特殊的两人口参数随机死亡率模型和其他多人口随机死亡率模型,并详细讨论了各类方法的模型思想、估计原理和拟合效果等内容。在此基础上,本文重点评述了各类模型的适用性和优缺点,总结了多人口建模方法在我国人口死亡率模型发展中的理论意义与应用价值,并展望了未来多人口随机死亡率模型的研究方向。

基于模糊聚类的多人口死亡率模型研究

面对严峻的全球养老局势,单独研究某个国家的死亡率效果往往欠佳,我们需要建立多人口死亡率模型来拟合和估计死亡率。研究多人口共同因子死亡率模型,可以更好地抓住被研究人口的共性和差异。由于大部分发达国家比我国的老龄化程度更深,本文由死亡率相互独立的Individual Lee-Carter模型提取14个国家和地区的年龄和时期效应,由三种聚类方法分别可视化。将共同年龄效应模型和联合K模型与模糊k-Means聚类和队列效应结合,构建四个新模型:模糊共同年龄效应模型、模糊联合K模型、r共同年龄效应模型和r联合K模型。数值结果表明与模糊k-Means聚类结合的模型,拟合和预测效果都很好。添加了队列效应的模型,受模型和出生年份限制,效果欠佳。所以共同因子死亡率模型可以提高预测精度和提供建设性建议。本文是利用机器学习研究多人口死亡率的有益尝试。

“一户多人口”电价政策下居民客户优选策略分析

通过对不同用电量区间客户执行“一户多人口”政策中的2种计费电价方案所产生的电费支出进行对比,以电费支出少的方案为优选策略的依据[1],并计算出损益平衡电量。帮助符合条件的居民用户做出更为科学的用电决策[3],算例分析验证了所提的方法的合理性与有效性[4]。

多人口发展中国家研究生教育比较研究及启示——以印度、巴西、墨西哥研究生教育改革发展为例

印度、巴西、墨西哥和中国同为多人口发展中国家,研究生教育体系的发展具有一定的相似性。从研究生教育在三国的发展历程、地位、招生培养机制、经费投入机制和质量评估机制等方面进行比较研究,并在此基础上对中国研究生教育体系改革提出有针对性的政策性建议。

多人口Lee-Carter随机死亡率模型比较与中国应用

文章梳理了多人口Lee-Carter随机死亡率模型进展与求解中存在的问题,推导了基于限制条件的两阶段加权最小二乘参数估计方法,并将中国大陆地区、香港特别行政区和台湾地区组成一个多人口群体,检验多人口随机死亡率模型在中国的适用情况。研究结果显示:(1)从估计方法看,基于限制条件的两阶段加权最小二乘估计法,能够有效避免多人口死亡率模型参数过多导致的极大似然估计方法失效的问题,并且方法简单、易于操作;(2)从拟合优度看,中国大陆地区人口死亡率短期预测适用Joint-k模型、长期预测适用ACF(0)模型,而香港和台湾地区无论长、短期均适用ACF(0)模型;(3)从稳健性看,多人口死亡率模型在中国人口死亡率拟合中稳健性较好,且基于修匀后数据的模型应用,能够显著提升拟合优度;(4)从预测结果看,带有附加时间效应因子的多人口随机死亡率模型能够得到一致的死亡率预测值,结果更加符合人类死亡率变动的经验特征,弥补了单人口死亡率模型的缺陷。

地丁分税 控制人口

人口的生产和再生产与物质资料的生产和再生产一样,是社会经济生活的重要组成部分。人口问题是个经济问题。因此,控制人口不仅要采取宣传、教育、计划指标等行政手段,而且也应采取经济手段。通过社会分配制度,从个人和家庭的经济利益上,对人口发展规定出某种范围,从而制约人口的发展。

动态死亡率模型的研究进展

死亡率的预测是人口预测的基础.近年来,死亡率建模方法不断取得新的进展,从最早的静态死亡率模型开始,死亡率模型不断发展为包括时间项的动态预测模型,如Lee-Carter族模型、CBD族模型等.本文对死亡率预测模型的相关文献进行了回顾和梳理.随着动态模型的发展,一些学者从死亡率改善水平入手,发展出一系列死亡率改善模型.另外,随着死亡率研究的深入,多人口死亡率的建模引起了研究者的重视,多人口预测模型迅速发展和完善.随着死亡率模型的研究方法不断丰富和创新,新兴统计学方法(如机器学习等)已经在死亡率建模中有所应用,拟合和预测准确度不断提升.除了经典的建模方法的扩展外,例如小区域人口或数据缺失的人口、高龄人口、相关人口等死亡率建模问题仍值得研究.

对共同年龄效应模型的研究及中国应用

共同年龄效应模型是一种在多个人口数据中提取所有数据对象所共有的共同年龄效应的多人口死亡率模型。我们首次运用共同年龄效应模型研究中国男女性死亡率。基于中国男女性死亡率数据,分别使用共同年龄效应模型的极大似然估计和Lee-Carter模型的最小二乘估计对数据进行了处理,结果表明共同年龄效应模型在处理中国男女性死亡率数据时,拟合和预测效果都很好。

Impact of anthropogenic disturbance on species diversity and vegetation structure of a lowland tropical rainforest of eastern Himalaya, India

Impact of anthropogenic disturbance on species diversity and vegetation structure of a lowland tropical rainforest was studied in the foothills of Eastern Himalaya, India. Tree species richness,density, basal area and the diversity indices were found significantly(P<0.05) decreased with the increasing level of disturbances whereas, shrub density, basal area and herb density significantly increased with increasing disturbance level. In case of shrubs, Simpson's dominance index significantly(P<0.007) increased along the disturbance gradient,whereas Pielou's evenness index significantly(P<0.005) decreased with an increasing level of disturbance. Shannon-Weiner diversity index for herbs significantly(P<0.016) increased with increasing disturbance whereas, Simpson's dominance index was significantly(P<0.013) declined along the disturbance gradient. Results revealed that10-50 cm dbh classes constituted the highest stem density, and highest basal area was recorded in the >100 cm dbh class in all three sites. Density of the matured trees decreased with increasing DBH whereas, tree basal area tended to increase with increasing DBH in all three sites. Tree species richness was highest in the lower DBH classes.62.07% of the total tree species regenerated in the largely undisturbed site followed by 50% in the mildly disturbed and 26.32% in the highly disturbed site.The overall regeneration condition was found to be good in the largely undisturbed site. Mildly disturbed site exhibited fair regeneration and so was in the highly disturbed site. Discernable variations in species composition, diversity, regeneration and tree population structure revealed the impact of anthropogenic disturbances on rainforest vegetation dynamics. Higher degree of disturbance was furtherly found not only affecting species diversity but also promoting the growth of invasive weed species.Dominance of Hydnocarpus kurzii and Crypteronia paniculata in the highly disturbed site also indicated that these less-valued timber species may benefit from the vegetation mosaic produced by the disturbance; so differences in abundance of these species may be useful for bio-indication. Furthermore,present study suggests the need of adequate biodiversity conservation measures and adaptation of sustainable forest management approaches in disturbed areas of lowland tropical rainforest in the foothills of eastern Himalaya, India.

Polymorphisms of ERCC1, XPD, XRCC1 and XPG Predict Clinical Outcome in Advanced Gastric Cancer Patients Receiving Oxaliplatin-Based Chemotherapy in Chinese Population

OBJECTIVE To investigate whether polymorphisms in ERCC1, XPD, XPG, XRCC1 genes are associated with clinical outcomes in advanced gastric cancer （AGC） patients treated with oxaliplatinbased chemotherapy. METHODS The genetic polymorphisms in ERCCI, XPD, XPG, XRCC1 were determined in 94 advanced gastric cancer patients treated with oxaliplatin-based chemotherapy, using TaqMan-MGB probes. The clinical response of 60 patients with stage IV disease, time to progression （TTP） and overall survival （OS） of 94 patients were evaluated. RESULTS The overall disease control rate （CR ＋ PR ＋ SD） of the 60 patients in stage IV was 70% （42/60）. Patients with XRCC1 399 G/G, XPG 46 C/C genotypes showed enhanced response to the oxaliplatin-based chemotherapy compared to those with other genotypes （P 〈 0.05）. The median OS and TTP of the patients were 5.5 months and 9.0 months, respectively. Among the 4 types of polymorphisms in the study, XRCC1 399 G/A ＋ A/A, XPG 46 C/T ＋ T/T genotypes were regarded to be associated with chemoresistance and poor survival （P 〈 0.05）. Combination analysis of the 2 polymorphisms using the Kaplan-Meier method revealed that the TTP and OS of the patients with a number of risk genotypes were significantly shortened （P 〈 0.05）. No significant association was found between the genotypes of the XPD codon 751, the ERCC1 codon 118 and the clinical outcome （P 〉 0.05）. CONCLUSION Testing for XRCC1 399, XPG 46 polymorphisms may allow identification of the gastric cancer patients who will benefit from oxaliplatin-based chemotherapy. Specific polymorphisms may influence clinical outcomes of AGC patients. Selecting specific chemotherapy based on pretreatment genotyping represents an innovative strategy that warrants prospective studies.

GST polymorphisms are associated with hepatocellular carcinoma risk in Chinese population

AIM: To investigate the association between GSTM1 and GSTT1 polymorphisms and the risk of hepatocellular carcinoma (HCC) in Chinese population. METHODS: Literature databases including PubMed, ISI web of science and other databases were searched.Pooled odds ratio (OR) and 95% CI were calculated using random- or fixed-effects model. Subgroup analysis and sensitivity analysis were also performed. RESULTS: Nineteen studies of GSTM1 (2660 cases and 4017 controls) and 16 studies of GSTT1 (2410 cases and 3669 controls) were included. The GSTM1/GSTT1 null genotypes were associated with increased risk of HCC in Chinese population (for GSTM1, OR = 1.487, 95% CI: 1.159 to 1.908, P = 0.002; for GSTT1, OR = 1.510, 95% CI: 1.236 to 1.845, P = 0.000). No publication bias was detected. In subgroup analysis, glutathione S-transferases polymorphisms were significantly associated with HCC risk among the subjects living in high-incidence areas, but not among the subjects living in low-incidence areas. CONCLUSION: The present meta-analysis suggests that GSTM1/GSTT1 null genotypes are associated with increased risk of HCC in Chinese population.

Polymorphisms of the TLR2 and TLR4 genes are associated with risk of gastric cancer in a Brazilian population

AIM： TO investigate toll-like receptor 2 （TLR2） -196 to -274 del, and TLR4 （＋896A/G rs4986790 and ＋1196C/ T rs4986791） polymorphisms at risk of chronic gastritis and gastric cancer in a Brazilian population and associ-ation of gastric lesions with risk factors such as smoking, alcohol intake and Helicobacter pylori infection.METHODS： In this casecontrol study, polymorphism at TLR2 -96 to -174 del was investigated by using the allele-specific polymerase chain reaction （PCR） method, while the PCR-restriction fragment length polymorphism technique was carried out to identify the TLR4 （rs4986790 and rs4986791） genotypes in 607 Brazilian individuals （208 with chronic gastritis-CG, 174 with gastric cancer-GC and 225 controls -C）.RESULTS： The single nucleotide polymorphisms TLR4＋1196ClT was not associated with risk of chronic gastritis or gastric cancer and the homozygous genotypes TLR4＋896GG and TLR4＋1196TF were absent in the studied population. However, the frequency of TLR2 -196 to -174 ins/del ＋ del/del and TLR4＋896AGgenotypes was significantly higher （P 〈 0.01 and P = 0.01, respectively） in the cancer group （33.4% and 11.5%, respectively） than in the control group （16.9% and 4.5%, respectively）. It was also observed that the G-C haplotype of the TLR4＋896A/G＋1196C/T （P = 0.02） and the combination of variant alleles of the TLR21TLR4＋896G （P = 0.02） are associated with susceptibility to gastric cancer. In addition, the multiple logistic regression showed that male gender [odds ratio （OR） = 2.70; 95% CI： 1.66-4.41; P 〈 0.01], alcohol intake （OR = 2.93; 95% CI： 1.76-4.87, P 〈 0.01）, TLR2 -196 to -174 del （OR = 2.64; 95% CI： 1.56-4.44; P 〈 0.01） and TLR4＋896G （OR = 3.19; 95% CI： 1.34- 7.61; P 〈 0.01） polymorphisms were associated with a higher susceptibility to developing this neoplasm.CONCLUSION： Our data indicate that T/R2 -196 to -174 del and TLR4＋896G may increase the risk of gastric cancer in a Brazilian population.

Risk factors and gene polymorphisms of inflammatory bowel disease in population of Zhejiang,China

AIM:To identify the risk factors and three single nucleotide polymorphisms(SNPs) of NOD2/CARD15 gene in inflammatory bowel disease(IBD) of the population in Zhejiang,China.METHODS:A case-control study was conducted using recall questionnaire to collect data on demographic,socioeconomic,lifestyle characteristics and dietary behaviors from 136 determined IBD patients and 136 paired healthy controls.COX regression method was used to screen the statistically significant risk factors for IBD.The polymorphisms of NOD2/CARD15 gene Arg702Trp,Gly908Arg and Leu1007fsinsC were genotyped and further compared between 60 patients with IBD and 60 healthy controls by polymerase chain reaction and restriction fragment length polymorphism.RESULTS:IBD occurred primarily in young and middle-aged people.The mean age for IBD patients was 42.6 years.The ratio of males to females was 1.23:1.COX regression indicated a higher statistical significance in milk,fried food and stress compared with the other postulated risk factors for IBD.None of the patients with IBD and healthy controls had heterozygous or homozygous SNPs variants.CONCLUSION:Milk,fried food and stress are associated with increased risk of IBD.The common variants in NOD2/CARD15 gene are not associated with IBD in China's Zhejiang population.

Geographical Patterns of Chinese Ethnic Minority Population Composition and Ethnic Diversity

Ethnicity is a carrier of language and culture.Spatial distribution of ethnic diversity is fundamental for identifying and reconstructing the migration patterns and evolution histories of cultures and languages.Utilizing the Chinese 4th National Census (1990) data,we investigated the specific time geographical patterns of population and diversity of Chinese ethnicminorities.As anticipated,results show that Chineseminorities are chiefly concentrated in dis-tant plateaus and mountains in the southwest,northwest and northeast of China.Further,population density centers of the 10 majorminorities are rather scattered,alternatively dominating at different parts of the country.This study pro-vides a first comprehensive quantitative test on a prevailing notion of 'six plates and three corridors' on the empirical clustering patterns of Chinese ethnicminorities.There are more consistent evidences supporting this notion in the north of China,with the central and southern regions showing more complex patterns,potentially transformed by processes such as migration,fragmentation,and percolation.The results of this study suggest that a geographical ap-proach can provide heuristic and complementary information for better understanding of historical social processes.

A polymorphism within ErbB4 is associated with risk for hepatocellular carcinoma in Chinese population

AIM:To investigate the association between hepatocel-lular carcinoma (HCC) susceptibility and a 12-bp inser-tion/deletion polymorphism (rs6147150) in the 3'UTR of ErbB4.METHODS:Using a case-control design,the rs6147150 genotypes in 270 patients with HCC and 270 healthy controls were determined by direct polymerase chain reaction and polyacrylamide gel electrophoresis.Logistic regression was used to analyze the association between the polymorphism and cancer risk.RESULTS:Computational modeling suggested that rs6147150 was located in the seed region of hsa-let-7c,a potential target sequence in ErbB4 3'UTR.Logistic re-gression analysis showed that,compared with individu-als homozygous for wild-type,heterozygotes [adjusted odds ratio (OR)=1.48,95% confidence interval (CI)= 1.03-2.17,P=0.034] and individuals homozygous for 12-bp del/del (OR=2.50,95% CI=1.37-4.56,P=0.001) were at significantly higher risk of HCC.Car-riers of the "del" allele of rs6147150 had a 1.59-fold increased risk for HCC (95% CI=1.22-2.07,P=0.003).CONCLUSION:rs6147150 may be associated with HCC risk,in part through let-7c-mediated regulation,and may be involved in the pathogenesis of HCC in Chi-nese populations.

Natural orifice translumenal endoscopic surgery: Progress in humans since white paper

Since the first description of the concept of natural orifice translumenal endoscopic surgery (NOTES), a substantial number of clinical NOTES reports have appeared in the literature. This editorial reviews the available human data addressing research questions originally proposed by the white paper, including determining the optimal method of access for NOTES, developing safe methods of lumenal closure, suturing and anastomotic devices, advanced multitasking platforms, addressing the risk of infection, managing complications, addressing challenges with visualization, and training for NOTES procedures. An analysis of the literature reveals that so far transvaginal access and closure appear to be the most feasible techniques for NOTES, with a limited, but growing transgastric, transrectal, and transesophageal NOTES experience in humans. The theoretically increased risk of infection as a result of NOTES procedures has not been substantiated in transvaginal and transgastric procedures so far. Development of suturing and anastomotic devices and advanced platforms for NOTES has progressed slowly, with limited clinical data on their use so far. Data onthe optimal management and incidence of intraoperative complications remain sparse, although possible factors contributing to complications are discussed. Finally, this editorial discusses the likely direction of future NOTES development and its possible role in clinical practice.

Genetic Biodiversity in Buffalo Population of Iraq Using Microsatellites Markers

Genetic structure of Iraqi buffalo population, in the South, Middle and North area of the country was characterized, using six microsatellite markers （ETHI52, ETH02, ETH225, CSSM060, BM1706 and INRA005）. Seventy alleles were detected across the six loci. Total number of alleles per locus （TNA） varied from 3 （INRA005 locus） to 16 （ETH 152 locus）. The mean number of allele （MNA） across the six loci in Iraqi indigenous buffalo was 11.4. The locus ETHI52 was the most polymorphic marker according to its number of allele （16）, the expected heterozygosity （0.86） and polymorphism information content （0.80） number of alleles （3）, expected Heterozygosity （0.1-0.2） and polymorphism information content （0.1-0.2）. Results showed that these markers were suitable in population genetics researches. It was concluded that a high degree of genetic diversity exist in the Iraqi buffalo populations.

A new discovered ABCA1 gene polymorphisms and the association of ABCA1 SNPs with coronary artery disease and plasma lipids in Chinese population

Single nucleotide polymorphisms （SNP） of ATP-binding cassette transporter A1 （ABCA1） gene are related to plasma lipid and susceptibility to coronary artery disease （CAD）. Our first goal was to screen all 50 coding regions of ABCA1 to find new SNPs. Our second goal was to investigate the frequency distribution of R1587K and M883I polymorphisms of ABCA1 gene, which are the variant occurred most frequently, in Chinese people and to evaluate their association with the CAD phenotype and plasma lipids. Methods： Single-strand conformation polymorphism （SSCP） and DNA sequence were used for confirming new SNP of ABCA1, and restriction fragment length polymorphism （RFLP） were applied for confirming genotypes of R1587K and M883I in 112 CAD cases and 108 healthy people. Results： We discovered a new ABCA1 SNP in Chinese population, which converse 233 amino acids from Methionine to Valine （M233V）. This new ABCA1 SNP located in exon7, and might potentially modulate the biological function of lipid metabolism. For R1587K and M883I SNPs, the K allele and I allele frequency was 28.9% and 31.1%, respectively. The K allele at R1587K conferred lower mean values of HDL-C in a dose-dependent manner in both CAD patients and healthy people. However, 883I allele was not associated with plasma lipid level. Neither 1587KK nor 883II associated with increased risk of CAD. Conclusion： Our study finds a potential functional ABCA1 SNPs and revealed K allele of R1587K associated decreased HDL-C level in Chinese population.

Association between MDM2-SNP309 and hepatocellular carcinoma in Taiwan Residents population

AIM:To investigate the risk association and compare the onset age of hepatocellular carcinoma(HCC) patients in Taiwan with different genotypes of MDM2- SNP309. METHODS:We analyzed MDM2-SNP309 genotypes from 58 patients with HCC and 138 cancer-free healthy controls consecutively.Genotyping of MDM2-SNP309 was conducted by restriction fragment length polymor- phism assay. RESULTS:The proportion of homozygous MDM2- SNP309 genotype(G/G)in cases and cancer-free healthy controls was similar(17.2%vs 16.7%).Multi-variate analysis showed that the risk of G/G genotypeof MDM2-SNP309 vs wild-type T/T genotype in patients with HCC was not significant(OR=1.265,95% CI=0.074-21.77)after adjustment for sex,hepatitis B or C virus infection,age,and cardiovascular disease/ diabetes.Nevertheless,there was a trend that GG genotype of MDM2-SNP309 might increase the risk in HCC patients infected with hepatitis virus(OR=2.568, 95%CI=0.054-121.69).Besides,the homozygous MDM2-SNP309 genotype did not exhibit a significantly earlier age of onset for HCC. CONCLUSION:Current data suggest that the asso- ciation between MDM2-SNP309 GG genotype and HCC is not significant,while the risk may be enhanced in patients infected by hepatitis virus in Taiwan.