Although excluding spots with very low intensity could eliminate the difference in performance between the Imin and Iavg pooling metrics, this approach would make it impossible to detect low-expressed regulated genes, which may be biologically significant.
However, the individual trees scattered in the desert are impossible to detect in low resolution remotely sensed data, e.g. NOAA AVHRR and MODIS, hitherto a main tool for monitoring vegetation change across African drylands.
For example, array-based methods are impossible to detect variations at a low frequency (many well below 1%) in the samples.
Very low stoichiometry of tyrosine phosphorylation makes it almost impossible to detect many tyrosine modifications on low-abundance proteins.
In their work on radioimmunoassay, Dr. Yalow and Dr. Berson used radioactive tracers to measure hormones that were otherwise difficult or impossible to detect because they occur in extremely low concentrations.
First, resonant SMS oscillations are impossible to detect on the ground or by a low-orbit satellite.
In the seventies and eighties many researchers thought it was impossible to detect plausible causal associations with such low-level exposures.
Not only are the smallest drones almost impossible to detect, radar does not work well at low altitudes, where its signals are obscured by hills and buildings.
HCCH-COSY spectrum analysis is a good example of the use SI labeling techniques in living organisms, since the natural abundance of 13C 13C bonds is very low (1/100×1/100 = 1/10000), making them impossible to detect without SI amendment.
For example, the low sampling rate and high level of observation noise make it impossible to detect relatively high vibration bridge frequencies (Meng 2002; Meng et al. 2007; Breuer et al. 2015; Górski, 2017).
One of the reasons why these genes were not detected by the gene prediction programs could be the presence of low quality sequences that may have lead to frameshifts, thus making them impossible to detect by these programs.
