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1. Tumor penetration of Sub-10 nm nanoparticles: Effect of dendrimer properties on their penetration in multicellular tumor spheroids

   https://doi.org/10.1016/j.nano.2019.102059  

   Bugno, Jason ; Poellmann, Michael J. ; Sokolowski, Karol ; Hsu, Hao-jui ; Kim, Dong-Hwan ; Hong, Seungpyo ( July 2019 , Nanomedicine: Nanotechnology, Biology and Medicine)
2. Examining Penetration Tester Behavior in the Collegiate Penetration Testing Competition

   https://doi.org/10.1145/3514040  

   Meyers, Benjamin S. ; Almassari, Sultan Fahad ; Keller, Brandon N. ; Meneely, Andrew ( July 2022 , ACM Transactions on Software Engineering and Methodology)

   Penetration testing is a key practice toward engineering secure software. Malicious actors have many tactics at their disposal, and software engineers need to know what tactics attackers will prioritize in the first few hours of an attack. Projects like MITRE ATT&CK™ provide knowledge, but how do people actually deploy this knowledge in real situations? A penetration testing competition provides a realistic, controlled environment with which to measure and compare the efficacy of attackers. In this work, we examine the details of vulnerability discovery and attacker behavior with the goal of improving existing vulnerability assessment processes using data from the 2019 Collegiate Penetration Testing Competition (CPTC). We constructed 98 timelines of vulnerability discovery and exploits for 37 unique vulnerabilities discovered by 10 teams of penetration testers. We grouped related vulnerabilities together by mapping to Common Weakness Enumerations and MITRE ATT&CK™. We found that (1) vulnerabilities related to improper resource control (e.g., session fixation) are discovered faster and more often, as well as exploited faster, than vulnerabilities related to improper access control (e.g., weak password requirements), (2) there is a clear process followed by penetration testers of discovery/collection to lateral movement/pre-attack. Our methodology facilitates quicker analysis of vulnerabilities in future CPTC events. 

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3. Static penetration assessment of stone weapon tip geometry metrics and comparison of static and dynamic penetration depths

   https://doi.org/10.1111/arcm.12841  

   Sitton, Jase ; Stenzel, Christopher ; Buchanan, Briggs ; Eren, Metin I. ; Story, Brett ( November 2022 , Archaeometry)

   Many factors governed the penetration efficacy of prehistoric projectile weaponry. Archaeologists broadly focus their efforts on understanding the effect of stone weapon tips because these specimens are often the only part of the weapon system that survives in the archaeological record. The tip cross‐sectional area (TCSA) and perimeter (TCSP) of stone weapon tips have been shown to correlate with target penetration depth. Here, using results from both static and dynamic penetration testing, we compare TCSA and TCSP against other tip geometry metrics: lateral surface area (LSA) and volume (V). Our analyses broadly show that using a single‐point geometry metric evaluated at multiple locations along the length of the point, or using multiple geometry metrics evaluated at a single location, better predicts required energy than using a single‐point geometry metric evaluated at a single location. Our results also show that in the case where a single geometry metric evaluated at multiple locations is used LSA provided the most robust prediction models. Finally, our results show that for the case where all geometry metrics evaluated at a single location are used the location that provides the most robust prediction model is dependent on how far the point penetrated the target.

    

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4. Multiscale analysis of rotational penetration in shallow dry sand and implications for self-burrowing robot design

   https://doi.org/10.1007/s11440-022-01492-x  

   Tang, Yong ; Tao, Junliang ( March 2022 , Acta Geotechnica)
5. Physical limits to meltwater penetration in firn

   https://doi.org/10.1017/jog.2021.44  

   Humphrey, Neil F. ; Harper, Joel T. ; Meierbachtol, Toby W. ( April 2021 , Journal of Glaciology)

   null (Ed.)

   Abstract Processes governing meltwater penetration into cold firn remain poorly constrained. Here, in situ experiments are used to develop a grain-scale model to investigate physical limitations on meltwater infiltration in firn. At two sites in Greenland, drilling pumped water into cold firn to >75 m depth, and the thermo-hydrologic evolution of the firn column was measured. Rather than filling all available pore space, the water formed perched aquifers with downward penetration halted by thermal and density conditions. The two sites formed deep aquifers at ~40 m depth and at densities considerably less than the air pore close-off density (~725 kg m −3 at −18°C, and ~750 kg m −3 at −14°C), demonstrating that some pore space at depth remains inaccessible. A geometric grain-scale model of firn is constructed to quantify the limits of a descending fully saturated wetting front in cold firn. Agreement between the model and field data implies the model includes the first-order effects of water and heat flow in a firn lattice. The model constrains the relative importance of firn density, temperature and grain/pore size in inhibiting wetting front migration. Results imply that deep infiltration, including that which leads to firn aquifer formation, does not have access to all available firn pore space. 

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