The rare AGG and AGA Arg codons in E. coli are well known to be problematic for expression of foreign proteins [2].
This left Psilotum as a "long branch" in the phylogenetic tree, and these are well known to be problematic.
However, it is well known that such testing is problematic because of the presence of nuisance parameters (Pesavento 2004) and the dependence of the distribution of the relevant test statistic on the variables included in the model.
It is well known that mixing at high loadings is problematic and requires more power to efficiently stir highly viscous slurries.
The discrepancy that exists between gene trees and a species tree, and also between nDNA and mtDNA trees, is well known [ 29- 31] and is especially problematic in closely related species or those with large population sizes [ 32], a situation commonly observed in Salmo.
PA-producing plants (e.g., tansy ragwort, coltsfoot, hound's tongue), especially Senecio species, have long been problematic in the western United States and are well known for livestock poisonings.
It is well known that the determination of pH or hydrogen ion concentrations (pcH) is important and problematic at 100°C and higher temperatures because of the inapplicability of glass electrodes under these conditions.
It is well known that in Rietveld refinements of heavy-atom structures, using X-ray diffraction data, much problematic intensity may be hidden in the thermal displacement factors of relatively light atoms.
This is particularly problematic when, as is often the case, some or many model parameters are not well known.
The evaluation of the best overall response for this patient has been problematic using the RECIST criteria, because these criteria do not contemplate a phenomenon documented in literature and well known in daily clinical practice called osteblastic flare.
Indeed, it is now well known that assessing OA progression on radiographs by measuring JSW and JSN, although the current gold standard for Agencies and Scientific Societies, 23 26 is problematic.
