Aberrant replacing

Fig. 4.2. Aberrant replaced right hepatic artery coming of the superior mesenteric artery (arrow) and aberrant accessory left hepatic artery (arrowhead) coming of the left gastric artery...

An aberrant hepatic artery refers to a branch that does not arise from its usual source (i.e. proper hepatic artery from the celiac trunk). This type of artery may be a substitute for the usual hepatic artery that is absent, in which case it is referred to as an aberrant replaced hepatic artery. In other cases there may be an additional artery to the one normally present hence the term aberrant accessory artery. 

Note the similarity of this to the formula for the Greenwood frequency (with v replaced by ujz.) If the aberration is corrected at the pupil for a given direction, the phase variance due to the anisoplanatism at an angle 0 is... 

O The acute leukemias are diseases of bone marrow resulting from aberrant proliferation of hematopoietic precursors. The hallmark of these malignancies is the leukemic blast cell, a visibly immature and abnormal cell in the peripheral blood that often replaces the bone marrow and interferes with normal hematopoiesis. These blast cells proliferate in the marrow and inhibit normal cellular elements, resulting in anemia, neutropenia, and thrombocytopenia. Leukemia also may infiltrate other organs, including the liver, spleen, bone, skin, lymph nodes, and central nervous system (CNS). Virtually anywhere there is blood flow, the potential for extramedullary (outside the bone marrow) leukemia exists. 

The statistical tests previously described assume that the data follow a normal distribution. However, the results obtained by several analytical methods follow different distributions. These distributions are either asymmetric or symmetric but not normally distributed. In some approaches, these distributions are considered to be aberrant values superimposed on the normal distribution. In the following approach, the arithmetic mean is replaced by the median (cf. 21.1) and the standard deviation is replaced by the mean deviation, MD. 

The first and best approach should be to examine the assay procedure that was used to try to find an explanation (e.g., a technical error or even a data recording error) for the outlying value. If a substantial technical error is found, then the outlying value may be discarded, and if possible the assay should be run again to replace it. If no such explanation is found, however, we still may wish to discard grossly aberrant values rather than repeat the entire set of n repetitions of the assay. One approach... 

Various tissue constructs have been reassembled from isolated constituents, including resident cell types whose numbers have been amplified or modified in culture. A three-dimensional co-culture system for human skin keratinocytes layered upon a synthetic mesh infiltrated with dermal fibroblasts, when floated to allow contact of the uppermost keratinocytes with air, exhibits stratification and cornification remarkably similar to in vivo squamous epithelia. This reconstructed epithelial model has been recommended as an in vitro replacement for dermal corrosivity testing. It has been anticipated that this and a similar noncomified model will have application in dermal and ocular irritation testing, but thus far validation studies have yielded mixed results. Reconstructed tissues can also provide context for basic toxicological research on aberrant cellular interactions with cellular and acellular constituents, as illustrated by invasion of cancerous epithelial cells into underlying dermis of a skin equivalent model. 

Although there is no inherent phase problem in the HREM technique it is replaced by an "instrumental" phase problem arising from the relatively imperfect nature of electromagnetic lenses. Spherical aberration is the chief limitation, and its effect can be coupled with that of deviation from the Qatissian focus into a phase factor which can be considered to act upon the diffracted amplitudes before re-combination by the lens to produce the initial image amplitude, namely ... 

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