Quantitative dynamic models help to achieve this understanding, but are difficult to construct and validate because of the scarcity of known mechanistic details and kinetic parameters.
Mathematics A Möbius Bagel, With a Schmear It is extremely time-consuming to bake scones into perfectly shaped conic sections (or sconic sections, as their inventor calls them), but not so difficult to construct tangrams out of toast slices, according to a delightful science blog post on The Guardian's Web site last week, titled "Geometry Bake-Off".
CATI methods (see page 13) are designed expressly to do this, but it is not difficult to construct written questionnaires to do so also.
A monetary valuation scheme is the most straightforward, but it may be difficult to construct such a scheme that adequately represents all aspects of the decision.
But these plants are hellishly difficult to construct.
Thus, closed-form solutions in the form of Green's functions are difficult to construct, but are quite valuable in their own right and often play the role of kernels in boundary integral equation formulations that are used for the solution of complex boundary-value problems of engineering importance.
But in general, ATs are more difficult to construct in practice because they are strongly application-dependent and because it is not always possible to determine a criterion to judge variant results (Di Giandomenico and Strigini [1990]).
This means not only that bacterial riboswitches regulating translation initiation are not available in eukaryotic translation systems, but also that it is physically difficult to construct eukaryotic ON riboswitches that regulate the eukaryotic canonical translation initiation, because an aptamer cannot be inserted upstream of the ribosome loading site.
It would be more difficult to construct this architecture from scratch, but however it's done, it's a must: a positive social justice message could be what tips the balance toward re-election for the president.
The lack of a conventional urban core in Los Angeles, along with comparatively low population densities, had made it difficult to construct modern rapid-transit systems there, but work on a subway system in Los Angeles began in the 1980s.
