The phrase "ascertained by these" is correct and usable in written English.
It can be used when referring to information or conclusions that have been determined or established through specific means or methods.
Example: "The results of the experiment were ascertained by these measurements, confirming the initial hypothesis."
Alternatives: "determined by these" or "established by these".
Potential cases of diabetes ascertained by these sources were verified against medical and pharmacy records.
23 Because there is much less protein binding of cortisone, levels of cortisone ascertained by these methods are more likely to reflect "free" levels.
Furthermore, symptoms ascertained by these measures have been associated with a number of clinical outcomes known to correlate with clinical depression and/or anxiety such as Parkinson's disease (Weisskopf et al. 2003), coronary heart disease, and sudden coronary death (Kawachi et al. 1994; Whang et al. 2009).
High proliferative index, angiogenesis, and protease activity in the mural ameloblastoma, ascertained by the expression of these markers, confirm its aggressive phenotype.
Their community language competency was ascertained by the fact that these workers were either employed currently or in the past as bilingual workers at other agencies or researchers, while their English language competency was ascertained to be of a sufficient level by the same criteria.
These insights were ascertained by the Chinese society without the benefit of precedence in other worldwide civilizations.
All women whose preeclampsia diagnosis was ascertained by the jury at the time these biochemical analyses were started, were included.
Undoubtedly, there is variability in the practice of these personal protective measures that was not ascertained by the study.
Lipoperoxidation was ascertained by the formation of MDA.
The extent of deterioration is ascertained by the vibration analysis.
Students' learning approaches were ascertained by the Approaches and Study Skills Inventory for Students.
