However, fluorescence measurements in wastewater treatment plants remain scarce due to difficulties with interpreting fluorescence data.
Current literature addressing this issue is extremely scarce due to the complexity in handling MSW's heterogeneity.
The radio spectrum available for wireless communication is extremely scarce due to the widely deployed wireless devices and services.
Nowadays the available wireless spectrum becomes more and more scarce due to increasing spectrum demand for new wireless applications.
Evaluation of plan implementation is very complex, and empirical study is scarce due to the methodological difficulties.
Unfortunately experimental data on gas diffusion coefficient in heavy oils are relatively scarce due to the tedious nature of diffusivity measurements.
It has become scarce due to the rapid growth of a variety of mobile devices and the emerging of many new mobile services.
In the early 1990s, the use of technology to support classroom instruction was scarce due to the lack of teacher knowledge.
However, knowledge of the impact of these interventions on injury or disease outcomes is scarce due to practical and methodological reasons.
Also experimental research on isolated column footings is scarce, due to the difficulties involved in the setup of the laboratory models and the cost of experiments.
But these, and even larger-scale studies, are scarce due to data limitations, taxonomic inconsistencies and practical issues in linking existing databases.
