Discrete-time linear periodic systems: gramian and modal criteria for reachability and controllability†

This paper deals with the reachability and controllability of periodic discrete-time systems. First, we supply two necessary and sufficient complete reachability conditions, which apply to reversible and non-reversible systems, respectively. Then, a necessary and sufficient complete controllability condition is provided. This condition, as well as the complete reachability criteria, is given in terms of the reachability gramian matrix. Equivalent modal criteria for reachability and controllability are established in the second part of the paper.     

Sequencing of a 40·5 kb Fragment Located on the Left Arm of Chromosome VII from Saccharomyces cerevisiae

The nucleotide sequence of a 40·5 kb DNA fragment from the left arm of chromosome VII of Saccharomyces cerevisiae was determined and analysed. Twenty-eight open reading frames (ORFs) longer than 300 nucleotides were identified. Eight of them correspond to the following known yeast genes: EMP24, GCN1, SPO8, COX13, CDC55, RPS26, COX4 and LSR1, also called GTS1. Twelve ORFs are new, among them eight show homology with other genes while four have no homology with any sequence in the databases. Eight additional ORFs are internal to or partially overlapping with other ORFs. The nucleotide sequence reported here is deposited in the EMBL database under the Accession Numbers X91837 and X91489. © 1997 by John Wiley & Sons, Ltd.     

多绳金刚石串珠锯的技术特点和加工成本分析（一）

本文是根据意大利大理石研究所的PAORO MARONI工程师,于2008年3月9日在第8届厦门国际石材展会的中国和意大利石材技术研讨会上的发言材料编译整理而成。主要介绍目前国际上饰面石材加工的最新技术——多绳金刚石串珠锯的使用、发展、工艺、技术特点和加工成本分析等内容。     

SIMPLIFIED FREQUENCY-DEPENDENT MODEL FOR INDUCTION MACHINES

ABSTRACT

The purpose of the present paper is the representation of the behaviour of induction motors, in the presence of harmonics in the power supply, by using a simplified frequency-dependent model. The model is the end product of statistical processing, which leads to the definition of “typical“ parameter values as a function of the frequency. This model is intended primarily for the study of harmonic power flow by means of computer programs. It has also been validated on a test network on which experimental results are available

Better rotating load models at harmonic frequencies can improve the studies of power quality in the design of the future electric power systems.     

Reconstruction of the absorption spectrum of an object spot from the colour values of the corresponding pixel(s) in its digital image: the challenge of algal colours

A novel procedure for deriving the absorption spectrum of an object spot from the colour values of the corresponding pixel(s) in its image is presented. Any digital image acquired by a microscope can be used; typical applications are the analysis of cellular/subcellular metabolic processes under physiological conditions and in response to environmental stressors (e.g. heavy metals), and the measurement of chromophore composition, distribution and concentration in cells. In this paper, we challenged the procedure with images of algae, acquired by means of a CCD camera mounted onto a microscope. The many colours algae display result from the combinations of chromophores whose spectroscopic information is limited to organic solvents extracts that suffers from displacements, amplifications, and contraction/dilatation respect to spectra recorded inside the cell. Hence, preliminary processing is necessary, which consists of in vivo measurement of the absorption spectra of photosynthetic compartments of algal cells and determination of spectra of the single chromophores inside the cell. The final step of the procedure consists in the reconstruction of the absorption spectrum of the cell spot from the colour values of the corresponding pixel(s) in its digital image by minimization of a system of transcendental equations based on the absorption spectra of the chromophores under physiological conditions.     

Quantitative Crack Surface Morphology of Bone Cements in Relation to Propagation Rate

Morphology of the crack surface of surgical bone cements has seldom been studied in the past despite the clinical relevance of cement failure. Previous studies on a specific cement type suggest that crack morphology depends on crack propagation rate. The objectives of this work were: (i) to develop a quantitative indicator for describing crack morphology; and (ii) to assess if dependency on crack‐propagation rate is affected by cement formulation. Known crack surfaces were obtained from specimens under controlled loading conditions. Crack surface roughness was measured for different crack‐propagation rates, and compared against the amount of cleaved pre‐cured beads (measured with a semi‐automated procedure based on micrographs). Such indicators were extremely robust, operator‐independent, highly correlated, and sensitive to the type of fracture. Moreover, it was found that crack surface morphology heavily depends upon cement composition. Thus, crack surface roughness is proposed as a method for quantitatively identifying crack morphology, and finally classifying fracture type.     

Stabilization of Anthocyanins of Blood Orange Fruit Juice

The stability of the red color of pigmented orange fruit juice was somewhat improved by pasteurization with microwaves and addition of tartaric acid and gluthathione as mildly acidic and antioxidant agents, respectively. Highest stability was obtained through the formation of complexes between anthocyanins and phenolic compounds, such as rutin and caffeic acid.     

AN EFFICIENT DNA-EXTRACTION PROTOCOL FOR NUT SEEDS

Establishing genetic origin of food products allows verification of the authenticity of valuable foods and discourages adulteration with material of lower cost and value. This is particularly important for food products that have obtained European recognition. The use of molecular markers could be a solution for species and cultivar identification and for the genetic traceability. The development of efficient DNA-extraction protocols is an essential step for the procedure. In this work, a method for total DNA isolation was developed for hazelnut, almond and walnut seeds. The efficiency and reliability of the method was tested by assessing quantity and quality of the extracted DNA, and by Polymerase Chain Reaction (PCR) amplification, using two decamer primers and three universal primer pairs designed on the chloroplast DNA. The success of amplifications confirmed the presence of both nuclear and chloroplast DNA in the extracted sample.

PRACTICAL APPLICATIONS

Cultivar identification of nuts, based on morphological traits only, is often difficult, and adulterations with seeds of lower cost and quality are easy, above all when they are sold as shelled kernel, as is common for hazelnut. The genetic identification of cultivars is nowadays a routine practice, because of the development of DNA-typing techniques based on molecular markers. An efficient DNA-extraction procedure for hazelnut, almond and walnut seeds is a preliminary step required for enabling the recognition of the cultivar of origin of the nuts and fighting commercial frauds. It will also be useful in marker-assisted selection, applied in breeding.     

HIGH-SPEED EXPERIMENTATION TECHNIQUES APPLIED TO THE SYNTHESIS OF TITANIUM SILSESQUIOXANE EPOXIDATION CATALYSTS

High-speed experimentation techniques are becoming powerful tools in many fields of chemical research, including catalysis. These techniques are characterized by the use of automated workstations that allow the preparation and the testing of a large number of small-volume samples in a short time. Here, high-speed experimentation techniques have been applied to the optimization of the synthesis of silsesquioxane precursors for titanium catalysts active in the epoxidation of alkenes. Different parameter spaces defined by the factors influencing the synthesis of silsesquioxanes were studied, and a very active and easy-to-prepare catalyst, based on silsesquioxanes obtained by the hydrolytic condensation of cyclopentyl trichlorosilane in acetonitrile, could be identified.