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At the outset a brief background from a pharmaceutics perspective is presented here. Pharmaceutical industry is one of the most tightly regulated industries. Statistics naturally plays an important role in the implementation of the compendial, regulatory and in-house requirements. The minimal requirement consists of a set of basic statistics, such as mean and standard deviation (SD), associated with each group of sample experimental data intended for submission. However, not only each statistic is individually subjected to a set of compendial, regulatory and in-house specifications, but also the individual observation is required to be within specific range for compliance (e.g. content uniformity). Hence these basic statistics are often referred to as the stand-alone sample (SAS) statistics, meaning that each statistic has to meet its own requirements. In this context, the geometric mean is indeed a SAS statistic. It is meaningful and interpretable directly from its face value. The geometric standard deviation (GSD) as derived in ref(B) is also a (SAS) statistic. It is meaningful and easily interpretable directly from its face value. It has the same sample information and the same interpretation as that of the regular SD. Sometimes, it shares essentially the same magnitude as the regular SD. Besides, it also has essentially the same magnitude as that of the jackknife GSD statistic, GSD(JK). For decades, these geometric statistics have been in practice, particulary, since the author of ref(B) was a member of the USP In-Vitro Bioavailability Testing Subcommittee (1970-1975). It has also been accepted fully and freely by the above-mentioned over-sight agencies.  相似文献   

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An analysis of the dispersion of elastic waves is presented for two types of long ultrasonics wave-guides that we qualify of “bimorph”: (i) a “three-layer” guide made of two different materials and (ii) a “clad core” guide built up of a rectangular core surrounded by a cladding, the materials of the rod and cladding having different properties. An analytical model is proposed to describe the extensional, flexural and torsional motions in “bimorph” wave guides having two geometrical and material symmetry axes. The asymptotic behaviour of the model allows one to select the material properties which lead to modes guided essentially either in the central layer or in the core of the bimorph guide. Moreover, the dispersive properties of a “bimorph” can be controlled through the choice of geometrical and material parameters.  相似文献   

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Silicon is the “veteran” semiconductor in the management of electrons. The recent quest for optoelectronic and photonic materials suggests that new architectures of silicon structured over multiple length scales may still be the optimum material for the transition from electron‐based to photon‐basped computers and communication systems. This Research News article is focussed on recent research accomplishments in fabrication and self‐assembly methods of shaping elemental silicon over nanometer to micrometer length scales for applications in electronics, optoelectronics, and photonics.  相似文献   

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A new first year, engineering orientation course has been put in place at NCSU. The course stresses integration with other first year courses, writing, team building, critical thinking, disciplinary thinking, and has a strong problem-solving component. Students were randomly selected to participate in the course. Students' attitudes about engineering and the first year experience were assessed using an instrument developed at the University of Pittsburgh and compared with the normal introduction to engineering course. Students in this course were more positive about their learning experience in the first semester, reported a higher satisfaction with all their courses, and were less likely to think that the first year courses were designed to “weed” students out of the program.  相似文献   

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If due to the market analysis a company makes the decision for the production of a new product by application of soldering and special the soldering with temporarily liquid solder, this one is then made specifically after that the company specific construction and production preparation. Either the decision for soldering is technically and/or economically well‐founded or she is even unavoidable by so‐called mixed material connections in the assemblies. This hybrid design finds application increasing today. In the contribution on hand the analysis and assessment of the soldering theory and practice is carried out under the point of view of the possible production of “ideal soldered connections” and “optimal soldered connections”.  相似文献   

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