Theoretical results on the discrete Weibull distribution of Nakagawa and Osaki

In this paper, we discuss some theoretical results and properties of the discrete Weibull distribution, which was introduced by Nakagawa and Osaki [The discrete Weibull distribution. IEEE Trans Reliab. 1975;24:300–301]. We study the monotonicity of the probability mass, survival and hazard functions. Moreover, reliability, moments, p-quantiles, entropies and order statistics are also studied. We consider likelihood-based methods to estimate the model parameters based on complete and censored samples, and to derive confidence intervals. We also consider two additional methods to estimate the model parameters. The uniqueness of the maximum likelihood estimate of one of the parameters that index the discrete Weibull model is discussed. Numerical evaluation of the considered model is performed by Monte Carlo simulations. For illustrative purposes, two real data sets are analyzed.     

DELAY ESTIMATION BY A HILBERT TRANSFORM METHOD

This paper describes an estimation of the time delay between two stationary time series signals, in which an input signal is measured with little noise and an output signal is the sum of a noise and the response from a linear system. We use the Hilbert transform relation for minimum delay systems to estimate the time delay. Some computer simulation results are given to evaluate the performance of the proposed method.     

Population regulation by dispersal over patchy environment;

Summary A mathematical model for the population regulation is presented, which takes into account the environmental heterogeneity and the animal dispersal, and does not contain any direct density effect on reproduction or death processes. Generally speaking, there are two kinds of dispersal, one is the density independent dispersal, the other is the density dependent. It is shown that a population equilibrium can be maintained by the density dependent dispersal or threshold dispersal which occurs only when the population density exceeds a certain threshold level, but that density independent dispersal by itself can not continue to maintain a population equilibrium.     

Infants born preterm and infants born full-term generate more selective leg joint movement during the scaffolded mobile task

Infants born very preterm (PT), prior to 32 weeks gestation, are at increased risk of developing cerebral palsy. Children with spastic cerebral palsy have impaired selective leg joint movement, which contributes to lifelong walking limitations. We investigated whether infants born PT generated more selective hip–knee joint movement (e.g., hip flexes as knee extends) while participating in a scaffolded mobile task. Infants born PT and infants born full-term (FT) at 4 months corrected age participated in a scaffolded mobile task for 2–3 consecutive days. The scaffolded mobile task required infants to raise their legs vertically over a virtual threshold. Three threshold heights (low, middle, and high) were used to test whether the middle and high heights encourage infants to move their legs more selectively. Fifteen infants born FT learned the task and showed more selective hip–knee movement at each of the three threshold heights on the day that they learned, compared with their baseline spontaneous kicking. Thirteen infants born PT learned the task and showed more selective hip–knee movement on their learning day, but only when the middle and high thresholds were used. The results show that the scaffolded mobile task effectively encouraged infants to generate more selective hip–knee joint movement.     

从比较信托法看中国信托法的立法及其解释

《中华人民共和国信托法》是亚洲第五部信托法 ,它在总体上是肯定的 ,但仍有一些值得商榷的地方。首先 ,从立法角度看中国信托法的条文 ,其定义非常明确 ,它构筑了信托的基本结构 ,但有一些不完善的地方需要改进 ;其次 ,从释义方面看中国信托法的条文 ,其内容不同程度地存在不周全的地方 ,在释义时容易使人产生误解 ,应该规定得更加明确和严密 ;再次 ,从经济方面看信托活用的效用 ,信托作为财产管理的制度具有无穷的效用 ,应该“用活”信托制度。     

Supplier quality assessment to identify depth technical knowledge of component reliability

As a result of global competition, international companies that manufacture photocopiers, printers or car navigation systems have to purchase low-cost electronic components such as semiconductors and hard disk drives by outsourcing production. However, it is often difficult for these companies to evaluate the quality of their suppliers through interviews and technical documentations. This article proposes new measures for supplier assessment and a systematic approach to select suppliers that have in-depth knowledge of component reliability and technology. The measures for selection not only include the physical quality of components but also information disclosures provided by suppliers, which consist of failure analysis, reliability data and details of the design-manufacturing process. The proposed measures are applied to real data of photocopier manufacturing enterprises. Experiments conducted show that a systematic assessment will enable selecting appropriate suppliers with a lower failure rate.     

Infants born full term and preterm increase the height of anti-gravity leg movements during a kick-activated mobile task using a scaffolded task environment

Prior research supports that infants born very preterm (PT), compared with full term (FT), have early differences in rate of learning and motor control that may hinder their ability to learn challenging motor tasks. Four-month-old infants born FT (n = 18) and PT (n = 18) participated in an infant kick-activated mobile task that was scaffolded to motivate progressively higher kicks. We found the FT group learned the association between their leg movements and mobile activation on the second day, but the PT group learned the association on the third day. Both groups of infants increased the height of their kicks on the day they learned the task, compared with their spontaneous kicking height. These findings suggest that infants born PT have the ability to learn challenging motor tasks, such as kicking high, when participating in a task environment that uses scaffolding.