Such trees have considerable palaeoclimatic potential due to their longevity and landscape survival times, but are challenging to sample non-destructively.
A very practical consideration is that imaging can assess receptor expression at sites that are challenging to sample and assay, for example, bone metastases, where de-calcification can make assay of tumor gene products challenging.
The analysis and determination of N-nitrosamines (NAs) in water samples are challenging and demanding.
Meanwhile, indeterminate samples are challenging for clinicians and researchers.
Although comprehensive, our sampling strategy was challenging to implement due to fluctuating work schedules and the number (pre- and post-shift on three consecutive days) and multiplicity (air, blood, exhaled breath, and urine) of samples collected.
While a causative agent is identified less than 50% of the time in elderly pneumonia patients, in nursing homes the percentage is even less; sputum production from patients for samples is challenging due to delirium, dementia, impaired cough reflex, and dehydration [ 15].
Due to the substantial increase in sample size it was challenging to recruit to target.
Thus, when applying random sampling ('shotgun') approaches it is challenging to obtain sufficient coverage for isoform detection and quantification.
Firstly, the present conclusions are based on a relatively small sample of patients, as it is challenging to collect a larger group of carefully selected KS patients with both MRI and PET data.
It is challenging to optimally sample the muscularis propria endoscopically for the diagnosis of muscle layer diseases, especially for motility disorders resulting from neuroenteric dysfunction.
