更深入地认识多重共线性

首先对多重共线性的概念和完全共线性下参数的不可估性,从不同的视角进行系统的剖析;其次对多重共线性的本质与根源做深入、具体的探讨;然后从理论上更为深刻地阐述当存在多重共线性时OLS估计量的统计特性以及为什么多重共线性是个问题;最后从五个侧面介绍解决多重共线性的方法以及各种方法的局限性和使用条件。

对多重共线性的深入思考

本文首先分析在完全共线情况下,模型参数的不可估性;其次从变量本身性质、数据性质和参数性质等不同视角揭示多重共线性的本质属性;最后从六个侧面介绍解决多重共线性的方法以及各种方法的局限性和使用条件。

Parallel Computation of Disjoint Products Approach

In this paper, extracting parallelizatio n from the sum of disjoint products approach is discussed. A general framework of parallelizing disjoint products approach is presented. And a parallel version of the newest disjoint products algorithm is implemented. The results of testing s how the effect is so good to get linear speedups.

Discrepancies in surface temperature between NCEP reanalysis data and station observations over China and their implications

Previous studies show that temporal irreversibility(TI),as an important indicator of the nonlinearity of time series,is almost uniformly overestimated in the daily air temperature anomaly series over China in NCEP reanalysis data,as compared with station observations.Apart from this highly overestimated TI in the NCEP reanalysis,some other important atmospheric metrics,such as predictability and extreme events,might also be overestimated since there are close relations between nonlinearity and predictability/extreme events.In this study,these issues are fully addressed,i.e.,intrinsic predictability,prediction skill,and the number of extreme events.The results show that intrinsic predictability,prediction skill,and the occurrence number of extreme events are also almost uniformly overestimated in the NCEP reanalysis daily minimum and maximum air temperature anomaly series over China.Furthermore,these overestimations of intrinsic predictability,prediction skill,and the number of extreme events are only weakly correlated with the overestimated TI,which indicates that the quality of the NCEP reanalysis should be carefully considered when conclusions on both predictability and extreme events are derived.

Assessment of Nutrients of Escamoles Ant Eggs Limotepum apiculatum M. by Spectroscopy Methods

Edible insects, escamoles ant eggs of the Formicidae family are consumed by cultural tradition at rural communities and by sensory characteristics at high class restaurants of Mexico; however, people ignore the importance of insect consumption in the nutrition of humans. Laboratory spectroscopy methods in food analysis represent benefits in time and precision. The aim of this study is to assess macronutrients and micronutrients of escamoles and eggs by spectroscopic methods to inform population the benefits they provide in health and to mention the advantage in the use of these techniques at laboratory work. Samples were gather the second week of March and April 2012, at Hidalgo State and analyze moisture and macronutrients by AOAC （Association of Official Analytical Chemistry） methods, amino acids by cation exchange chromatography, tryptophan was determined by a colorimeter method, fatty acids by GC （gas chromatography） using helium as a carrier （AOAC）, fat soluble vitamins A, D and E by HPLC （high performance liquid chromatography）, and minerals by atomic absorption spectrophotometers and phosphorus by colorimeter （AOAC）. Data showed high amount in proteins, lipids and minerals; low in fiber and soluble carbohydrates; contained all essential amino acids. Fatty acids contain monounsaturated and polyunsaturated. Fat soluble vitamins A, D and E. Minerals： sodium, phosphorus, potassium, magnesium, calcium and manganese. Escamoles ant eggs include polyunsaturated fatty acids essential for mental development, vitamin A to prevent eye diseases, vitamin E as antioxidant and vitamin D involved in calcium absorption that low intake, impair grow and bone health. Iron and zinc contained anemia. Regarding the laboratory benefits, needs less expensive chemicals, testing is clean, rapid and easy results of multiple samples, but it is required to handle by qualified chemists. In conclusion, data may change according to biotic and abiotic conditions of the environment; however, escamoles have all nutrients in adequate balance to improve human health; and provide faster and precise results.

Fair Value Disclosure, External Appraisers, and the Reliability of Fair Value Measurements

By developing an analytical model, this paper examines the role of the ＂external appraiser＂ as a tool to face the informational asymmetry issue related to fair value measurements. A comparison between such a signaling mechanism and a ＂full fair value disclosure＂ is firstly carried out, highlighting variables affecting the efficiency and the effectiveness of both information strategies. Then, recovering the traditional distinction between ＂protective disclosure＂ （hard information） and ＂informative disclosure＂ （soft information）, this paper demonstrates how the former could significantly increase the positive effects associated to an employment of an independent valuer, reaching some conclusions useful to the standard setting process.

System Design Of Security Evaluation For Data Link Communications

Data link communication requires data communication process must have reliability, availability, confidentiality, availability, integrity, non-repudiation, controllability.This has a great effect to ensure the normal communication functions.In this paper the author on the basis of many years of work experience, first discussed the establishment of a risk assessment system data link,then focused on the problem of index weight assessment.To data communication security, this research article will provide some references.