Gas emissions from underground sites to the atmosphere depend on many factors. Pressure drops are considered to be the most important. However, emissions can also be observed during the initial phase of the pressure rise, following a previous drop in pressure. On the other hand, gas emissions may not be detected when the pressure drops, especially when a previous pressure rise has taken place. The aim of the research was to determine the role of variations in baric tendency on airflow rate and its direction. To solve this problem a numerical model was built utilizing the Ansys Fluent software package. Subsequently, three scenarios of baric tendency variations were tested: a) rise – drop, b) drop – drop, c) drop – rise. The results showed inert behavior of gases. Under scenario (c), 1 hour after the change in tendency gases still were flowing out to the atmosphere. Considering scenario (a), it was proved that even during a pressure drop gas emissions do not take place, which can be crucial for further determination of the gas hazard at the surface or for assessment of the rate of gas emissions from a particular gas emitter. Scenario (b) merely gave an overview of the process and was mainly used for validation purposes. It gave a maximal CO2 concentration of 2.18%vol (comparable to measurements) and a CO2 mass flow rate 0.15kg/s. Taking into account greenhouse gas emissions this amounted to 514 kg CO2/h.

Introduction: Our umbrella review aimed to summarize and revisit the evidence from all of the meta-analyses and systematic reviews regarding the treatments of oropharyngeal squamous cell carci-noma (OPSCC).
Materials and Methods: Major medical databases such as PubMed, Scopus, Embase, Web of Science, Google Scholar, Cochrane Library, BIOSIS, and EBSCO were searched. The overall search process was conducted in 3 stages.
Results: Finally, a total of 28 studies met the inclusion criteria and were included in this study. Out of those 28 meta-analyses, a total of 315 primary studies were screened in order to extract the data and perform the statistical analysis. In total, data from 22,619 patients was analyzed.
Conclusion: The main objective of the present umbrella review was to summarize and analyze all of the evidence-based data provided by numerous meta-analyses and systematic reviews regarding the treatment of OPSCC. Our study delivers the most up-to-date and evidence-based results regarding the different therapeutic modalities of this malignancy in one concise review, making it the ultimate tool for physicians treating OPSCC.