复杂产品外购系统关键特性的质量事前控制策略

探索一套基于质量合同的外购产品质量事前控制方法，以辅助复杂产品主制造商管理外购产品的质量。通过在采购合同中设计奖惩策略，在不对称质量信息下诱使供应商自发地保证其产品的关键特性具备最优质量水平，最大限度地提升供应链质量收益并消除私有质量信息的不良影响。针对某商用飞机公司和某航空发动机公司的质量合作开展案例研究，验证上述模型和方法的可行性和有效性，为复杂产品质量控制问题提供了一类崭新的研究思路和解决方法。     

What mechanisms/processes underlie radiation-induced genomic instability?

Radiation-induced genomic instability is a modification of the cell genome found in the progeny of irradiated somatic and germ cells but that is not confined on the initial radiation-induced damage and may occur de novo many generations after irradiation. Genomic instability in the germ line does not follow Mendelian segregation and may have unpredictable outcomes in every succeeding generation. This phenomenon, for which there is extensive experimental data and some evidence in human populations exposed to ionising radiation, is not taken into account in health risk assessments. It poses an unknown morbidity/mortality burden. Based on experimental data derived over the last 20?years (up to January 2012) six mechanistic explanations for the phenomenon have been proposed in the peer-reviewed literature. This article compares these hypotheses with the empirical data to test their fitness to explain the phenomenon. As a conclusion, the most convincing explanation of radiation-induced genomic instability attributes it to an irreversible regulatory change in the dynamic interaction network of the cellular gene products, as a response to non-specific molecular damage, thus entailing the rejection of the machine metaphor for the cell in favour of one appropriate to a complex dissipative dynamic system, such as a whirlpool. It is concluded that in order to evaluate the likely morbidity/mortality associated with radiation-induced genomic instability, it will be necessary to study the damage to processes by radiation rather than damage to molecules.     

Bats along the Republican River and its tributaries in southwestern Nebraska: distribution, abundance, and reproduction

Thirteen species of bats occur in Nebraska, but limited information is available on those inhabiting southwestern parts of the state. We investigated the distribution, abundance, and reproductive activity of bats in 5 counties in extreme southwestern Nebraska (Chase, Hays, Dundy, Hitchcock, and Red Willow). From April 2007 to April 2008, we deployed mist nets on 15 occasions at 8 localities over the Republican River and its tributaries. We captured 100 individuals representing 5 species, including the evening bat ( Nycticeius humeralis ), eastern red bat ( Lasiurus borealis ), hoary bat ( Lasiurus cinereus ), big brown bat ( Eptesicus fuscus ), and silver-haired bat ( Lasionycteris noctivagans ). All species raised young in this region of Nebraska, except L. noctivagans , which was documented only during migration. Lactating females of N. humeralis captured on 15 June and volant young captured on 23 June extend known dates of reproductive activity for this species in the state, and an adult female captured on 30 April represents the earliest seasonal record of this species from Nebraska. Our records of evening bats also extend the known distribution of this species farther west in Nebraska than previously reported. Changes in land use throughout the Great Plains during the last century have altered many habitats, such as gallery forests associated with rivers, and distributions of mammals, including bats, have shifted to reflect those ecological changes.     

Population structure and paternity in an American black bear ( Ursus americanus ) population using microsatellite DNA

We report genetic microsatellite data from analysis of 71 American black bears ( Ursus americanus ) from the East Tavaputs Plateau in eastern Utah. Heterozygosity was 52.9%, which is lower than other mainland North American populations and possibly reflects low recruitment into the study area. We used a combination of known pedigrees (mother/cubs), relatedness estimates, and paternity estimation using CERVUS to infer single and possible multiple paternity within litters, breeding by pairs over consecutive years, and the possibility of a single male successfully breeding with multiple females in a single year. Estimates of inbreeding effective population size indicate the East Tavaputs Plateau population is part of a larger black bear population.     

No supernovae associated with two long-duration gamma-ray bursts

It is now accepted that long-duration gamma-ray bursts (GRBs) are produced during the collapse of a massive star. The standard 'collapsar' model predicts that a broad-lined and luminous type Ic core-collapse supernova accompanies every long-duration GRB. This association has been confirmed in observations of several nearby GRBs. Here we report that GRB 060505 (ref. 10) and GRB 060614 (ref. 11) were not accompanied by supernova emission down to limits hundreds of times fainter than the archetypal supernova SN 1998bw that accompanied GRB 980425, and fainter than any type Ic supernova ever observed. Multi-band observations of the early afterglows, as well as spectroscopy of the host galaxies, exclude the possibility of significant dust obscuration and show that the bursts originated in actively star-forming regions. The absence of a supernova to such deep limits is qualitatively different from all previous nearby long-duration GRBs and suggests a new phenomenological type of massive stellar death.     

Prediction intervals for exponential smoothing using two new classes of state space models

Three general classes of state space models are presented, using the single source of error formulation. The first class is the standard linear model with homoscedastic errors, the second retains the linear structure but incorporates a dynamic form of heteroscedasticity, and the third allows for non‐linear structure in the observation equation as well as heteroscedasticity. These three classes provide stochastic models for a wide variety of exponential smoothing methods. We use these classes to provide exact analytic (matrix) expressions for forecast error variances that can be used to construct prediction intervals one or multiple steps ahead. These formulas are reduced to non‐matrix expressions for 15 state space models that underlie the most common exponential smoothing methods. We discuss relationships between our expressions and previous suggestions for finding forecast error variances and prediction intervals for exponential smoothing methods. Simpler approximations are developed for the more complex schemes and their validity examined. The paper concludes with a numerical example using a non‐linear model. Copyright © 2005 John Wiley & Sons, Ltd.