This study provides no information on informal caregivers who did not respond, as it was highly difficult to assess demographic data when refusal was stated during the invitation phone call.
This is particularly true inasmuch as any adverse environmental impacts of space activities are highly difficult to mitigate once they have materialized.
As for China, carbon source deficiency currently prevails, and a low carbon-to-nitrogen (C/N) ratio in wastewater treatment is highly difficult (Peng et al. 2009).
"We do make every effort to track down perpetrators, but it's extremely difficult as these are highly-organised operations".
In light of the growing demand for accelerators, acceptance can be highly competitive and entry as difficult as a high school senior applying to an Ivy League college.
Vmax and km can be highly correlated, making it difficult to estimate both as random effects parameters (Between-subject variability section).
It's difficult to be highly motivated all of the time on your own.
Complications of diverticulitis may be highly variable, and it may be difficult to diagnose diverticulitis as an underlying cause of severe complications.
Wrangling the data is difficult, since formats can be highly divergent between companies.
If you start, you will find it very difficult to stop as it is known to be highly addictive.
