Causality and forecasting in incomplete systems

In this paper we examine how causality inference and forecasting within a bivariate VAR, consisting of y(t) and x(t), are affected by the omission of a third variable, w(t), which causes (a) none, (b) one, and (c) both variables in the bivariate system. We also derive conditions under which causality inference and forecasting are invariant to the selection of a bivariate or a trivariate model. The most general condition for the invariance of both causality and forecasting to model selection is shown to require the omitted variable not to cause any of the variables in the bivariate system, although it allows the omitted variable to be caused by the other two. We also show that the conditions for one-way causality inference to be invariant to model selection are not sufficient to ensure that forecasting will also be invariant to the model selected. Finally, we present a numerical illustration of the potential losses, in terms of the variance of the forecast, as a function of the forecast horizon and for alternative parameter values—they can be rather large, as the omission of a variable can make the incomplete model unstable. © 1997 John Wiley & Sons, Ltd.     

Cointegration,error-correction models,and forecasting using realigned foreign exchange rates

This study employs error-correction models (ECMs) to forecast foreign exchange (FX) rates where the data-sampling procedures are consistent with the rules governing the settlement (delivery) of FX contracts in the FX market. The procedure involves thatching (aligning) the forward rate to the 'actual' realized (future) spot rate at the settlement (delivery) date. This approach facilitates the generation of five different sets of sub samples of FX rate series for each currency. For comparative purposes, non-aligned month-end rates are also examined. The results indicate that the moments of the realized forecast errors for the same currency are not similar. Further, the ECMs derived are unstable, and their forecasting performance vary. The forecasting performance of the ECMs appear to be affected by the choice of the interval in which the sets of sub samples are observed. These results are attributed to the observed seasonal variation in FX rates.     

MAIT cells and pathogen defense

Mucosa-associated invariant T (MAIT) cells are a unique population of innate T cells that are abundant in humans. These cells possess an evolutionarily conserved invariant T cell receptor α chain restricted by the nonpolymorphic class Ib major histocompatibility (MHC) molecule, MHC class I-related protein (MR1). The recent discovery that MAIT cells are activated by MR1-bound riboflavin metabolite derivatives distinguishes MAIT cells from all other αβ T cells in the immune system. Since mammals lack the capacity to synthesize riboflavin, intermediates from the riboflavin biosynthetic pathway are distinct microbial molecular patterns that provide a unique signal to the immune system. Multiple lines of evidence suggest that MAIT cells, which produce important cytokines such as IFN-γ, TNF, and IL-17A, have the potential to influence immune responses to a broad range of pathogens. Here we will discuss our current understanding of MAIT cell biology and their role in pathogen defense.     

On the limitations of comparing mean square forecast errors

Linear models are invariant under non-singular, scale-preserving linear transformations, whereas mean square forecast errors (MSFEs) are not. Different rankings may result across models or methods from choosing alternative yet isomorphic representations of a process. One approach can dominate others for comparisons in levels, yet lose to another for differences, to a second for cointegrating vectors and to a third for combinations of variables. The potential for switches in ranking is related to criticisms of the inadequacy of MSFE against encompassing criteria, which are invariant under linear transforms and entail MSFE dominance. An invariant evaluation criterion which avoids misleading outcomes is examined in a Monte Carlo study of forecasting methods.     

Selection for resistance toBacillus thuringiensis δ-endotoxin in an insect cell line (Choristoneura fumiferana)

Summary A cell line of the spruce budworm (FPMI-CF1) consists of a mixed population of cells that possess variable sensitivity to -endotoxin from crystals ofBacillus thuringiensis. A cell strain was selected from FPMI-CF1 which was resistant to the entomocidal protein extracted fromB. thuringiensis crystals. The resistant character was unstable, however, and could not be maintained in the absence of toxin during growth.The author wishes to thank S.S. Sohi (Forest Pest Management Institute, Canadian Forestry Service, Sault Ste. Marie, Ontario, Canada) for theC.fumiferana cell line, and L.I. Davidson (USDA) for his able technical assistance.     

基于模型突变检测的管道泄漏检测定位方法

为了改进负压波法在管道微弱泄漏的检测和定位中的效果,提出了基于模型突变检测的特征提取和泄漏定位算法。首先运用广义似然比检测理论,建立压力信号变化的统计检验模型,计算广义似然比比率r和下降幅度d作为压力信号突变发生的敏感特征,并通过求得的压力变化时间点进行泄漏定位。针对缓慢泄漏时压力信号变化的特点,提出了相应的改进模型,更精确的求出缓慢泄漏压力信号的下降拐点。实验证明,参数r和d对不同变化类型的压力信号有较好的区分度,利用管道内压力和流量信号的特征值作为神经网络的特征向量可以实现管道的微弱泄漏识别,且基于改进模型的定位算法在缓慢泄漏定位中有较好的定位结果和稳定度。     

Invariant natural killer T cells in adipose tissue: novel regulators of immune-mediated metabolic disease

Adipose tissue (AT) represents a microenvironment where intersection takes place between immune processes and metabolic pathways. A variety of immune cells have been characterized in AT over the past decades, with the most recent addition of invariant natural killer T (iNKT) cells. As members of the T cell family, iNKT cells represent a subset that exhibits both innate and adaptive characteristics and directs ensuing immune responses. In disease conditions, iNKT cells have established roles that include disorders in the autoimmune spectrum in malignancies and infectious diseases. Recent work supports a role for iNKT cells in the maintenance of AT homeostasis through both immune and metabolic pathways. The deficiency of iNKT cells can result in AT metabolic disruptions and insulin resistance. In this review, we summarize recent work on iNKT cells in immune regulation, with an emphasis on AT-resident iNKT cells, and identify the potential mechanisms by which adipocytes can mediate iNKT cell activity.     

A new technique for dissociation of hair follicles into single cells

Summary A method is described for the complete dissociation of mouse hair follicles into a suspension of single cells suitable for cell culture. Dermal tissue containing hair follicles is digested sequentially with trypsin and chondroitinase ABC under mild conditions.     

A new technique for dissociation of hair follicles into single cells.

A method is described for the complete dissociation of mouse hair follicles into a suspension of single cells suitable for cell culture. Dermal tissue containing hair follicles is digested sequentially with trypsin and chondroitinase ABC under mild conditions.     

Prospects for a new account of time reversal

In this paper I draw the distinction between intuitive and theory-relative accounts of the time reversal symmetry and identify problems with each. I then propose an alternative to these two types of accounts that steers a middle course between them and minimizes each account׳s problems. This new account of time reversal requires that, when dealing with sets of physical theories that satisfy certain constraints, we determine all of the discrete symmetries of the physical laws we are interested in and look for involutions that leave spatial coordinates unaffected and that act consistently across our physical laws. This new account of time reversal has the interesting feature that it makes the nature of the time reversal symmetry an empirical feature of the world without requiring us to assume that any particular physical theory is time reversal invariant from the start. Finally, I provide an analysis of several toy cases that reveals differences between my new account of time reversal and its competitors.     

Selection and validation of differentially expressed genes in head and neck cancer

We applied a robust combinatorial (multi-test) approach to microarray data to identify genes consistently up- or down-regulated in head and neck squamous cell carcinoma (HNSCC). RNA was extracted from 22 paired samples of HNSCC and normal tissue from the same donors and hybridized to the Affymetrix U95A chip. Forty-two differentially expressed probe sets (representing 38 genes and one expressed sequence tag) satisfied all statistical tests of significance and were selected for further validation. Selected probe sets were validated by hierarchical clustering, multiple probe set concordance, and target-subunit agreement. In addition, real-time PCR analysis of 8 representative (randomly selected from 38) genes performed on both microarray-tested and independently obtained samples correlated well with the microarray data. The genes identified and validated by this method were in comparatively good agreement with other rigorous HNSCC microarray studies. From this study, we conclude that combinatorial analysis of microarray data is a promising technique for identifying differentially expressed genes with few false positives.Received 12 February 2004; received after revision 22 March 2004; accepted 14 April 2004     

Location of a lure by the drumming insectPimpla instigator (Hymenoptera,Ichneumonidae)

Summary Females of the parasitoidPimpla instigator (Hymenoptera, Ichneumonidae) are able to locate a lure hidden in a paper sheath. The lure is located without having been touched or sighted, and without any olfactory stimuli. We propose that the ability to locate the lure is linked with the drumming behavior of the females.     

Forecasting recessions using the yield curve

We compare forecasts of recessions using four different specifications of the probit model: a time invariant conditionally independent version; a business cycle specific conditionally independent model; a time invariant probit with autocorrelated errors; and a business cycle specific probit with autocorrelated errors. The more sophisticated versions of the model take into account some of the potential underlying causes of the documented predictive instability of the yield curve. We find strong evidence in favour of the more sophisticated specification, which allows for multiple breakpoints across business cycles and autocorrelation. We also develop a new approach to the construction of real time forecasting of recession probabilities. Copyright © 2005 John Wiley & Sons, Ltd.     

Die Genomsonderung in den Mitosen der Rattenleber

Summary Model squashes with gelatine cubes containing 8 files like the chromosomes ofBellevalia romana (2n=8) showed the chromosomes only in groupings that correspond to the original position of metaphase chromosomes. The metaphase chromosomes in root tip cells ofBellevalia romana are arranged at random; there is neither somatic pairing nor genome segregation (= grouping of metaphase chromosomes into two complete chromosome sets). In contradiction to these results, the chromosomes in the regenerating liver cells (2n=42) show a certain precentage of grouping into complete genomes. It is concluded that in rat liver cells a mechanism exists which, starting with the genome segregation, may produce a change in chromosome number. Thus these same euploid or aneuploid chromosome numbers can be explained which are really observed in normal and treated rat liver. 4 possibilities of such mechanism are discussed.

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Nach einem Vortrag, gehalten anlässlich des IV. Symposium histologicum internationale Lausanne (Suisse), 5.–8. September 1961.     

Amyloid β-induced FOXRED2 mediates neuronal cell death via inhibition of proteasome activity

Proteasome inhibition has been regarded as one of the mediators of Aβ neurotoxicity. In this study, we found that FOXRED2, a novel endoplasmic reticulum (ER) residential protein, is highly up-regulated by Aβ in rat cortical neurons and SH-SY5Y cells. Over-expression of FOXRED2 inhibits proteasome activity in the microsomal fractions containing ER and interferes with proteasome assembly, as evidenced by gel filtration and native gel electrophoresis analysis. In contrast, reduced expression of FOXRED2 rescues Aβ-induced inhibition of proteasome activity. FOXRED2 is an unstable protein with two degradation boxes and one KEN box, and its N-terminal oxidoreductase domain is required for proteasome inhibition. Ectopic expression of FOXRED2 induces ER stress-mediated cell death via caspase-12, which is inhibited by Salubrinal. Further, down-regulation of FOXRED2 expression attenuates Aβ-induced cell death and the ER stress response. These results suggest that up-regulated FOXRED2 inhibits proteasome activity by interfering with 26S proteasome assembly to contribute to Aβ neurotoxicity via an ER stress response.     

Influence of the carbohydrate moiety on the growth inhibitory activity and adhesiveness of 3T3 cell plasma membranes

Summary Treatment of 3T3 cell plasma membranes with glycosidase enzymes decreased their ability to inhibit cell growth and also decreased their binding to 3T3 cells. This suggests that carbohydrate is required for complete function of inhibitory activity and that inhibition is associated with membrane adhesion.     

Influence of the carbohydrate moiety on the growth inhibitory activity and adhesiveness of 3T3 cell plasma membranes

Treatment of 3T3 cell plasma membranes with glycosidase enzymes decreased their ability to inhibit cell growth and also decreased their binding to 3T3 cells. This suggests that carbohydrate is required for complete function of inhibitory activity and that inhibition is associated with membrane adhesion.     

基于ANSYS的石油井架风载的有限元分析

为了研究全自动带压修井机井架承受风载的受力情况,找出井架结构的应力集中点,利用有限元分析软件ANSYS对其进行实体三维建模,施加风载荷并求解,得到结构在各个方向上的应力云图以及变形图;找出结构在承受风载的薄弱处;避免出现较大应力。这对于提高井架的质量非常有益。此方法可以有效地获得和真实工矿相符合的结果;令石油井架稳定性达到了要求;对类似结构的设计分析也具有一定的参考价值。