Nonlinearities in the Impact of Industry Structure: the Case of Concentration and Intra-industry Variability in Rates of Return

This paper addresses the issue of industry concentration andintra-industry variability in rates of return. An inverted ‘U’relationship is hypothesized and tested in which one observeslow levels of variability both at high and low levels of concentration,in one case as a result of collusion and the other as a resultof competition. In the process, the paper highlights the benefitsassociated with combining both industry and firm levels of analyses.     

基于SVM的维吾尔文文本分类研究

文本自动分类技术在提高文本信息利用的有效性和准确性上具有重要的现实意义和广阔的应用前景。随着Internet上维吾尔文信息的迅速发展,维吾尔文文本分类成为处理和组织这些大量文本数据的关键技术。研究维吾尔文文本分类相关技术和方法,针对维吾尔文文本在向量空间模型表示下的高维性,本文采用词干提取和χ2统计量相结合的方法对表示空间进行降维。采用SVM算法构造了维吾尔文文本分类器。针对维吾尔文文本分类语料进行的实验结果表明,SVM分类器的MacroF1值达到了84.6%,明显好于kNN方法。     

FUZZY REASONING USING POSITIONAL INFORMATION

Abstract

The paper argues in favour of reasoning methods that process positional information, i.e. information about the position of the input with respect to the class prototype, and thus achieve a better specification of the corresponding output class. It is shown that such an approach leads to reducing or cancelling unwanted nonlinearities (of input-output characteristic) imposed by reasoning methods, nonlinearities that alter the dependence expressed in the knowledge base. Two methods which use positional information are presented: (a) the mapping of o-cut borders (MACB) (Stoica, 1993, Proc. Fifth IFSA World Congress, pp. 1266-1269), inspired from a particular interpretation of the representation theorem and (b) the Left/Right Centre of Gravity (L/R COG) (Ghanayem, 1995, Proc. IEA/AIE, pp. 41 -45). The methods are tested in implementing a power system stabiliser (PSS) Simulation results show better performance of methods that use positional information, as compared with classic Mamdani (Mamdani, 1975, International Journal of Man-Machine Studies, 7, 1-13) reasoning. Reflections on a “best” reasoning method conclude the paper.     

EVALUATION OF BIOGENIC AMINES FORMATION BY PROTEOLYTIC ENTEROCOCCI STRAINS ISOLATED FROM RAW DROMEDARY MILKS FROM SOUTHERN ALGERIA

Twenty-three strains of lactic acid enterococci isolated from dromedary raw milks in Southern Algeria were investigated for their proteolytic activity and ability to produce biogenic amines by decarboxylating amino acids: histidine, tyrosine and ornithine. All strains tested displayed proteolytic activities, but none of them were able to produce detectable biogenic amines in the usual adequate laboratory media, namely, Joosten and Northolt medium and Leuschner medium. Polymerase chain reaction experiments indicate a positive correlation between the absence of the hdc and odc genes and the lack of histamine and putrescine production for all tested strains. By contrast, all strains appeared to possess tdc gene, but no correlation was found with a negative expression of tyrosine decarboxylase.

PRACTICAL APPLICATIONS

In foods, biogenic amines are mainly generated by decarboxylation of the corresponding amino acids through substrate-specific enzymes of the microorganisms present in this environment, particularly histidine, tyrosine, lysine, ornithine and arginine, and the capability of enterococci and some other lactic acid bacteria to produce biogenic amines has been described. For this purpose, several qualitative and quantitative methods to determine biogenic amines production by these microorganisms have been developed. There is great interest to identify and to characterize the bacteria strains intended for an industrial use and to verify if they are potentially able to produce biogenic amines in order to prevent it's synthesis and limit the poisoning risk.     

MOSFET的大信号动态集总模型及射频电路模拟

针对 RF电路模拟的需要 ,在文中提出了一个基于表面势的 MOSFET大信号动态集总模型。这个模型是由 MOSFET的 PDE模型简化推导而来。它不仅比传统的模型能更精确地描述晶体管在高频大信号情况下的伏 -安特性 ,而且比 PDE模型易于求解 ,从而大大提高了电路模拟的速度。通过模拟几个具体的 RF电路 ,将这个模型与 PDE模型作了比较 ,结果表明两者吻合得很好。     

Application of ferrous sulfate alleviates negative impact of cadmium in rice (<i>Oryza sativa</i> L.)

Soil contamination with toxic heavy metals [such as cadmium (Cd)] is becoming a serious global problem due to rapid development of social economy. Iron (Fe), being an important element, has been found effective in enhancing plant tolerance against biotic and abiotic stresses. The present study investigated the extent to which different levels of Ferrous sulphate (FeSO₄) modulated the Cd tolerance of rice (Oryza sativa L.), when maintained in artificially Cd spiked regimes. A pot experiment was conducted under controlled conditions for 146 days, by using natural soil, mixed with different levels of CdCl₂ [0 (no Cd), 0.5 and 1 mg/kg] together with the exogenous application of FeSO₄ at [0 (no Fe), 1.5 and 3 mg/kg] levels to monitor different growth, gaseous exchange characteristics, oxidative stress, antioxidative responses, minerals accumulation, organic acid exudation patterns of O. sativa. Our results depicted that addition of Cd to the soil significantly (P < 0.05) decreased plant growth and biomass, gaseous exchange parameters, mineral uptake by the plants, sugars (soluble, reducing, and non-reducing sugar) and altered the ultrastructure of chloroplasts, plastoglobuli, mitochondria, and many other cellular organelles in Cd-stressed O. sativa compared to those plants which were grown without the addition of Cd in the soil. However, Cd toxicity boosted the production of reactive oxygen species (ROS) by increasing the contents of malondialdehyde (MDA), which is the indication of oxidative stress in O. sativa and was also manifested by hydrogen peroxide (H₂O₂) contents and electrolyte leakage to the membrane bounded organelles. Although, activities of various antioxidative enzymes like superoxidase dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) and non-enzymatic antioxidants like phenolics, flavonoid, ascorbic acid, anthocyanin and proline contents increased up to a Cd level of 0.5 mg/kg in the soil but were significantly diminished at the highest Cd level of 1 mg/kg in the soil compared to those plants which were grown without the addition of Cd in the soil. The negative impacts of Cd injury were reduced by the application of FeSO₄ which increased plant growth and biomass, improved photosynthetic apparatus, antioxidant enzymes, minerals uptake together with diminished exudation of organic acids as well as oxidative stress indicators in roots and shoots of O. sativa by decreasing Cd retention in different plant parts. These results shed light on the effectiveness of FeSO₄ in improving the growth and upregulation of antioxidant enzyme activities of O. sativa in response to Cd stress. However, further studies at field levels are required to explore the mechanisms of FeSO₄-mediated reduction of the toxicity of not only Cd, but possibly also other heavy metals in plants.     

A study of the occurrence of Listeria species in raw sheep milk

The occurrence of bacteria from the genus Listeria in raw sheep milk and traditional local cheese was studied in three regions of the Karak district of Jordan. Conventional plating methods for the detection of Listeria species were followed to determine the average and the percentage of the contaminated samples. The result shows that there were significant differences between the regions in the study concerning the average and the percentage of positive occurrences of Listeria species in raw sheep milk. The results also showed that mainly L. monocytogenes and, to a lesser degree, L. ivanovii and L. innocua were found in the milk samples, while the occurrence of L. monocytogenes in cheese samples was very low.     

Controllability of linear time-varying systems with delay in control†

This paper is concerned with the study of controllability of linear systems with delay in the control function. It has been illustrated that many of the techniques which proved to be useful in the study of linear systems with no delay (alman et al. 19G2, Kroindlcr and Sarachik 1964) can be generalized when dealing with systems having delay in the control.

An explicit expression is given for transferring a given state to any desired state using minimum control energy.

The corresponding conditions for linear time-invariant systems (ebakhy and Bayoumi 1971) are obtained as a special case. Extensions to multiple- delays systems are also included.

A new degree of controllability is introduced and the corresponding criteria are obtained.