Because children are likely to be exposed to multiple environmental chemicals, and because these chemical exposures may be correlated with each other, it is challenging to isolate associations.
This bacterium is challenging to isolate and cultivate, as it replicates in short lifespan cells (i.e. polynuclear cells), which rapidly undergo autolysis after sampling.
Given the interest and use of educational technologies and consequent interest by researchers, it is often challenging to isolate the major issues that have been or can be addressed by academic research.
H. cinaedi is extremely challenging to isolate, and therefore needs special laboratory practice.
The causes of change (or stasis) in policy and practice are difficult to predict ahead of time and are often just as challenging to isolate and identify after the fact.
I've been warned that as well as seeing patients, I'll need to keep track of hospital supplies, possibly face widespread cholera or measles outbreaks, and must help set up treatment for patients with tuberculosis and HIV, both diseases that come with complex pathologies and social issues that are challenging to treat anywhere, let alone in isolated Lulimba.
Because young infants in developing countries are also breast-fed, it is challenging methodologically to isolate the relative contributions to protection that each of these confers.
Evaluating the economic impact in individual cases, and the health system in general, is challenging due to difficulty isolating costs directly attributable to hyponatremia versus those only associated with underlying diseases.
An expansion in protected areas will be challenged by geographically isolated micro-endemics, varied endemic patterns among taxa, increasing deforestation, resource extraction, and changes in climate.
Second, in studies dealing with differential exposures to macronutrients, it is a major challenge to isolate the macronutrient truly responsible for the nutrigenetic effects, particularly for fat and carbohydrates as they tend to be manipulated in such a way that one is compensated by the other.
