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排序方式: 共有274条查询结果,搜索用时 15 毫秒
251.
252.
目的测量颈椎高度建立四川汉族女性人群的身高推算方程,为法医学个人识别提供帮助。方法应用计算机X线摄影放射学方法,在209例四川汉族女性颈椎CR片上测量C3~C7椎体高度,并准确测量身高。按年龄是否大于45岁进行分组,对各颈椎的测量数据与身高进行线性回归分析,建立颈椎推算身高的回归方程。结果共建立一元回归方程36个,多元回归方程12个,所有回归方程经线性回归模型假设检验,均有统计学意义(P〈0.05)。所建立的回归方程的复相关系数(r)在0.628~0.280范围内,回归方程的标准误在4.03~5.03cm范围内。结论本研究所建立的回归方程,可用于四川汉族女性颈椎的身高推算。 相似文献
253.
《国际相互影响》2012,38(3):367-385
Do military regimes spend more on the military than other regime types? All leaders cater to their winning coalition. For military leaders, core supporters are other members of the military. To solicit support from this group, first, leaders are persuaded to spend more on the military to ensure their political survival, while other autocratic leaders tend to view the military as a competing power center. Second, the cost of repressing challenges from the public in military regimes is cheaper than in other regimes; therefore, leaders in military regimes allocate more resources to the military to satisfy them. We test this argument by examining military spending in different regime types for 1960–2000. The empirical results from Prais-Winsten regression with panel-corrected standard errors indicate that military regimes allocate more, on average, to the military than other regimes and that military rulers brought into power through military coups or who have experienced military coup attempts against them increase their military resource allocation. 相似文献
254.
Aziz N Greenwood PF Grice K John Watling R van Bronswijk W 《Journal of forensic sciences》2008,53(5):1130-1137
Pressure-sensitive adhesive tapes often represent key evidence of crimes such as assault, rape or homicide; thus, the development of analytical techniques able to contribute to a detailed characterization of these materials is of forensic importance. The gas chromatography-mass spectrometry (GCMS) analysis of the solvent extractable fractions of a suite of electrical and gaffer adhesive tapes spanning a range of colors and manufacturers identified a number of petroleum-derived hydrocarbons. Molecular and isotopic analyses of hydrocarbon constituents of complex materials have found wide analytical utility including the forensic investigation of oil spills and arson. Here, we investigate the utility of these techniques for characterizing the hydrocarbon composition of pressure-sensitive adhesive tapes for forensic correlation purposes. Subtle distinction of tape samples was evident in the GCMS distribution of several hydrocarbon groups including alkyl-naphthalenes, hopane and sterane biomarkers. Linear discriminant analysis of the abundances of these products provided high level differentiation of tape manufacturer. The distinction of different adhesive tape samples was further extended by measurement of their stable carbon isotopic values. The molecular and isotopic differences of the petroleum content of tapes are consistent with the use of different petroleum materials used in the manufacturing process and demonstrate the benefits of the combined use of complementary oil hydrocarbon characterization approaches. This study reveals the forensic potential of using established petroleum characterization methods for characterizing materials with a petroleum-derived hydrocarbon element. 相似文献
255.
Modeling the Deviant Y in Criminology: An Examination of the Assumptions of Censored Normal Regression and Potential Alternatives 总被引:1,自引:1,他引:0
Christopher J. Sullivan Jean Marie McGloin Alex R. Piquero 《Journal of Quantitative Criminology》2008,24(4):399-421
Many dependent variables of criminological interest have censored distributions. Investigations that use such variables increasingly
have turned to the Tobit model, a censored regression technique that is specified based on a latent dependent variable. When
used under suitable circumstances, this model provides appropriate estimates. This paper discusses key assumptions of the
Tobit model. It then highlights the risk of violating these assumptions and reviews alternative flexible parametric and semiparametric
modeling techniques, currently used sparingly in criminology, which researchers may find helpful when assumptions regarding
the error terms are untenable. By using an empirical example focused on sentencing outcomes and comparing estimates across
analytic methods, this study illustrates the potential utility of simultaneously estimating the Tobit model along with some
alternatives.
相似文献
Christopher J. SullivanEmail: |
256.
Evangelia Papapetrou 《Economic Change and Restructuring》2008,41(2):155-166
The paper studies the earnings differential between genders in Greece employing quantile regression analysis and applying
a variant of the selection-adjusted Oaxaca and Ransom (1994) decomposition methods to explain the components of the wage differentials. The results suggest that, in Greece, substantial
differences in wages between men and women can be identified. Decomposing the wage gap between genders the results show that
the difference in wages is attributed mainly to the unexplained part and to a lesser extent to the employee’s endowment. In
all deciles of the wage distribution the wage differentials between genders are not explained by differences in the productive
characteristics of the employed but rather they constitute the unexplained part of the wage differential.
相似文献
Evangelia PapapetrouEmail: |
257.
Karin Hoisl 《The Journal of Technology Transfer》2009,34(2):212-225
Although labor mobility has been recognized as a key mechanism for transferring tacit knowledge, prior research on inventors
has so far hardly discussed the impact of a move on inventive performance. Additionally, existing research has neglected the
differences in gains from a move between high and lower performing inventors. This paper adds to the current R&D literature
by presenting a jointly estimated quantile regression to compare the coefficients of the explanatory variables at different
points of the performance distribution. Additionally, dummy variables are used to compare inventive performance prior and
in the aftermath of a move. Results reveal that inventors at the upper end of the performance distribution are better able
to benefit from a move to draw level with or to overtake non-movers in the post-move period. Whereas at the bottom of the
performance distribution a higher level of education has a positive impact on inventive performance, education does not matter
significantly at the upper end of the performance distribution. Data for the analysis was derived from a survey of German
inventors (N = 3,049).
相似文献
Karin HoislEmail: |
258.
Nicholas D. K. Petraco Ph.D. ; Carol Gambino M.S. ; Thomas A. Kubic Ph.D. ; Dayhana Olivio Nicholas Petraco M.S. 《Journal of forensic sciences》2010,55(1):34-41
Abstract: In the field of forensic footwear examination, it is a widely held belief that patterns of accidental marks found on footwear and footwear impressions possess a high degree of "uniqueness." This belief, however, has not been thoroughly studied in a numerical way using controlled experiments. As a result, this form of valuable physical evidence has been the subject of admissibility challenges. In this study, we apply statistical techniques used in facial pattern recognition, to a minimal set of information gleaned from accidental patterns. That is, in order to maximize the amount of potential similarity between patterns, we only use the coordinate locations of accidental marks (on the top portion of a footwear impression) to characterize the entire pattern. This allows us to numerically gauge how similar two patterns are to one another in a worst-case scenario, i.e., in the absence of a tremendous amount of information normally available to the footwear examiner such as accidental mark size and shape. The patterns were recorded from the top portion of the shoe soles (i.e., not the heel) of five shoe pairs. All shoes were the same make and model and all were worn by the same person for a period of 30 days. We found that in 20–30 dimensional principal component (PC) space (99.5% variance retained), patterns from the same shoe, even at different points in time, tended to cluster closer to each other than patterns from different shoes. Correct shoe identification rates using maximum likelihood linear classification analysis and the hold-one-out procedure ranged from 81% to 100%. Although low in variance, three-dimensional PC plots were made and generally corroborated the findings in the much higher dimensional PC-space. This study is intended to be a starting point for future research to build statistical models on the formation and evolution of accidental patterns. 相似文献
259.
重庆地区汉族未成年人牙龄推断的研究 总被引:1,自引:1,他引:0
目的运用牙齿曲面断层影像技术,研究6周岁~15周岁重庆市未成年人牙齿钙化的规律,从而建立根据牙齿钙化程度推断年龄的方法。方法依据牙齿钙化分级标准对1321名(男性577名,女性744名)重庆市6周岁~15周岁未成年人牙齿曲面断层片上的牙齿钙化程度进行分级评分;将评分值与对应的性别和年龄分别输入SPSS13.0软件进行统计分析,最终建立推断年龄的方程。结果左右侧同名牙齿钙化程度无统计学差异(P〉0.05),但性别间有统计学差异(P〈0.05);下颌左右侧8颗牙齿的钙化程度与年龄相关系数均大于0.58;所建利用不同牙齿组合推断年龄的线性回归模型调整拟合优度均大于0.67,估计值标准误男性为0.95周岁~1.11周岁、女性为1.02周岁~1.12周岁。结论该方法可用于法庭科学领域中推断重庆市6周岁~15周岁未成年人活体以及尸体的年龄。 相似文献
260.