DIVERSITY OF PERCEPTIONS OF MEAT TENDERNESS AND JUICINESS BY CONSUMERS: A TIME-INTENSITY STUDY

Seven judges, untrained in sensory assessment, were trained in the use of Time Intensity (TI) and asked to monitor the tenderness and juiciness of a range of cooked beef and pork samples. The subjects were given no definitions concerning sensory cues to monitor in their assessments, nor did they confer with each other. The shapes of the TI curves they recorded for tenderness and juiciness differed between individuals, although there were similarities in the curve shapes for the 2 attributes for each individual. Correlations between the intensity parameters of the curves (maximum intensity and area under curve) and the chewing time were not significant for the subjects as a group for tenderness, although significant correlations were found for some of the subjects when examined individually. The results indicate that subjects differ in their concepts of sensory tenderness and juiciness, and that perceived tenderness does not correlate with chewing time for all subjects. In more general terms the study supports the use of TI assessments for interpreting individual differences in sensory perceptions.     

Enamel alteration following tooth bleaching and remineralization

The purpose of this study was to compare the effects of professional tooth whitening agents containing highly concentrated hydrogen peroxide (with and without laser activation), on the enamel surface; and the potential of four different toothpastes to remineralize any alterations. The study was performed on 50 human molars, divided in two groups: treated with Opalescence^® Boost and Mirawhite^® Laser Bleaching. Furthermore, each group was divided into five subgroups, a control one and 4 subgroups remineralized with: Mirasensitive^® hap+, Mirawhite^® Gelle?, GC Tooth Mousse? and Mirafluor^® C. The samples were analysed by SEM/3D‐SEM‐micrographs, SEM/EDX‐qualitative analysis and SEM/EDX‐semiquantitative analysis. The microphotographs show that both types of bleaching cause alterations: emphasized perikymata, erosions, loss of interprizmatic substance; the laser treatment is more aggressive and loss of integrity of the enamel is determined by shearing off the enamel rods. In all samples undergoing remineralization deposits were observed, those of toothpastes based on calcium phosphate technologies seem to merge with each other and cover almost the entire surface of the enamel. Loss of integrity and minerals were detected only in the line‐scans of the sample remineralized with GC Tooth Mousse?. The semiquantitative EDX analysis of individual elements in the surface layer of the enamel indicates that during tooth‐bleaching with HP statistically significant loss of Na and Mg occurs, whereas the bleaching in combination with a laser leads to statistically significant loss of Ca and P. The results undoubtedly confirm that teeth whitening procedures lead to enamel alterations. In this context, it must be noted that laser bleaching is more aggressive for dental substances. However, these changes are reversible and can be repaired by application of remineralization toothpastes.     

An examination of land use change due to irrigated agriculture in north‐eastern Jordan using geoinformatics

The Jordanian government has encouraged irrigated agriculture since the early 1990s by providing low cost loans to drill private wells. The impacts of this practice on land use change were examined within a small (362 km²) area of the Jordanian Badia using Geoinformatics. Aerial photographs, SPOT and Landsat TM imageries were used, in a GIS environment, to map and examine changes in the farming patterns since 1990. Field surveys and questionnaires were used to ground truth the remotely sensed data. The results indicate that the cultivated area has increased from just 28.5 ha in 1990 to over 1000 ha in 2000 and that the number of farms has increased from 2 to 32 over the same time period. Furthermore, farm locations are moved annually restricted by the position of the well and land availability; this also causes land use change.     

ON THE PROBLEM OF REPRESENTATION IN LOCKEAN AND DIALECTICAL BELIEF SYSTEMS: A SYSTEMS APPROACH TO POLICY ANALYSIS

This paper explores the problems that are associated with building a model (representation) of two systems which are central to the field of policy analysis. The systems are the Lockean and Dialectical Inquiring Systems (ISs). Given two or more belief systems, a Lockean IS will attempt to secure maximum agreement between them, whereas a Dialectical IS will attempt to secure maximum disagreement as the basis for forming a policy.     

固体氧化物燃料电池氧化还原反应热流场模拟

为了研究固体氧化物燃料电池的氧化还原反应的热流场分布情况,建立了氧化还原反应的热流场环境.设计了连接管式高温炉的气体通路,研究了固体氧化物燃料电池在氧化还原反应中热流场的控制方式,分析了氧化还原反应热流场计算条件,并使用数值模拟工具进行计算与模拟.实验结果表明:氧化还原反应热流场的温度分布可以分为293 K、324.111 K、355.222K、386.333K、417.444K、448.556K、479.667K、510.778K、541.889K和573K等9个温度场分布等值区域,X坐标方向速度场分布范围为-0.200 261~0.177 592,Y坐标方向速度场分布范围为-0.275 204~0.260 32,及速度矢量范围为0~0.284 156,有助于显现氧化还原气体分布状况和氧化还原反应渐变过程.     

Surface Composition of Porous Glass

Both boron and silicon were detected on the surface of porous glass. Infrared and adsorption data show five or six times more boron in the surface than can be expected from chemical analysis of the porous glass. It is suggested that the excess of boron in the surface occurs during the leaching of the base glass.     

Knowledge Representation Using Fact Segments

A central part of the construction of an expert system is the way in which the knowledge is represented. A computer can only store and manipulate knowledge in discrete chunks representing approximations to the real world, but the human mind can work on an infinitely variable sliding scale representing real-world values. The greater the computerized discretization, the more precise the computer model becomes. The knowledge base within a computer expert system can take many forms depending on the type of domain problem, the language of execution and the nature of the system.
The GWX expert system gives advice on groundwater control in excavations for construction projects. The system was written in Prolog and the knowledge base was created by breaking information down into very small pieces, each referring to a segment of data—fact segment—about precise details of the domain. The way in which fact segments have been devised for the GWX expert system is described.     

直流电源驱动的等离子体点火器的点火特性

为获得等离子体点火器点火特性,使用自行设计的等离子体点火装置,对不同进口氩气压力和工作电流条件下的等离子体点火器高温射流特性和放电特性进行了实验研究,利用光谱仪对点火器出口处的发射光谱特征进行了测量,并根据光谱特征计算了等离子体的激发温度。结果表明:等离子体点火器的高温射流长度随进口氩气体积流量的增大先增大后减小,随工作电流的增大而增大;等离子体点火器的弧电流随进口氩气体积流量的增大而减小,随电源输出电流增大而增大;等离子体点火器出口射流的激发温度随工作电流的增大而增加,随氩气体积流量的增大而减小,所得结果对等离子体点火系统在航空发动机的实际应用具有一定的指导意义和参考价值。     

INFLUENCE OF CHEWING EFFICIENCY ON TEXTURE AND FLAVOUR PERCEPTIONS OF FOOD

This study examined the effect of differences in chewing efficiency on selected panellists' perceptions of the stickiness and flavour of cooked pasta. Chewing efficiency was measured by the degree of breakdown of an almond, and weight loss of chewing gum after predetermined numbers of chews. Pasta was cooked for various lengths of time in tomato juice to provide a series of samples varying in texture and flavour. The attributes considered in this study were clearly understood and detected in all of the samples by all the subjects. Nevertheless the subjects differed in the time intensity representations of their perceptions of these attributes. Differences in the efficiencies with which subjects break down food in the mouth may account for the abilities of subjects to distinguish between samples in terms of texture and flavour.