Challenges noted during the initial studies included (a) difficulty in achieving optimum dilution and residence time while sustaining isokinetic sampling for high flue gas velocities; (b) inaccuracies in measurement and control of sampling system flow rates to maintain a balanced flow system; and (c) particle depositions in several system components.
We then adopted those items which included a difficulty level of 0 and a discrimination power of 2 or higher.
18 Limitations of prospective studies include a difficulty in controlling for bias and a loss to follow-up.
Obstacles to complex trials include a difficulty to make experimental practice changes, ideological resistance to or ignorance of trials, unknown levels of generalizability, and costs.
Exposure to trauma in childhood predicts life-long problems in social relationships, including a difficulty trusting others, poor-quality relationships, and an elevated risk of re-victimization and developing a variety of chronic physical health problems [ 28, 29].
These include (a) difficulties delivering interventions to the community en masse due to constraints in the workforce and health care resources [ 25, 26], (b) limited availability of evidence-based interventions and clinicians in routine practice, especially in rural areas, and (c) low participation rates even if access to those interventions is at little or no costs [ 27].
This includes acknowledging a difficulty or a challenge and telling yourself it's okay that it's occurring.
To establish that the paradigm had sufficient power to reveal reaction time effects on auditory word recognition, each experiment also included a task difficulty manipulation.
Reasons for this omission typically include (a) the difficulties in reliably characterizing stress dependent effects from a limited number of pressure buildup (PBU) tests, and (b) large uncertainties in our understanding of both the porosity and compressibility of coals.
