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The Masing conditions establish a criterion to relate the loading curve of a hysteretic system (e.g., systems with friction or plasticity) to its complete hysteresis loop. For the field of joint mechanics, where hysteretic models are often used to describe the dissipative, tangential behavior within an interface, the Masing conditions allow for significant computational savings when the normal load is constant. In practice, though, jointed systems experience time varying normal forces that modify the tangential behavior of the system. Consequently, the hysteretic behavior of jointed structures do not adhere to the Masing conditions. In this work, this discrepancy between the Masing conditions and behavior exhibited by jointed structures is explored, and it is hypothesized that if the Masing conditions accounted for variations in normal force, then they would more accurately represent jointed structures. A new set of conditions is introduced to the original set of Masing conditions, yielding a « Masing manifold » that spans the tangential displacement-tangential force-normal force space. Both a simple harmonic oscillator and a built-up structure are investigated for the case of elastic dry friction, and the results show that the hysteresis of both of these systems conforms to the three dimensional Masing manifold exactly, provided that a set of constraints are satisfied, even though the hysteresis does not conform with the original Masing conditions. 

“It ain’t necessarily so” – A favored mantra recited by R. K. Trench in the context of “received truth,” or established beliefs; and the title of his unfinished autobiography. Professor Robert (Bob) Kent Trench’s research career brought together multiple disciplines in the study of mutualistic symbioses that are crucial to understanding the physiology, ecology, and co-evolution of metazoan and protist associations, many of which are beneficial to the Earth’s biosphere. Through the development and use of complementary techniques, he pioneered important discoveries about metabolically coupled interactions between “plants” and animals. Having grown up in Belize (formerly British Honduras), his journey in academia started at the University College of the West Indies (UCWI) on the island nation of Jamaica, then proceeded to the University of California, Los Angeles (USA); Oxford University (UK); and Yale University (Connecticut, USA). He was a longtime faculty member in the Department of Ecology, Evolution and Marine Biology at the University of California, Santa Barbara (Figs. 1a–f). Over the course of his life (August 3 1940–April 27 2021), he recognized that many things presented as fact were often accumulated dogma. His direct application of the scientific method ultimately helped to change these misconceptions. By deconstructing established ‘beliefs,’ he greatly improved our understanding of several mutualistic symbioses, and many of his insights and hypotheses published decades ago remain at the forefront of intense investigation to this day. 

In this work, a proteolytic digest of cytochrome c (microperoxidase 11, MP-11) was used as a model to study the structural aspects of heme protein interactions and porphyrin networks. The MP-11 structural heterogeneity was studied as a function of the starting pH ( e.g. , pH 3.1–6.1) and concentration ( e.g. , 1–50 μM) conditions and adduct coordination. Trapped ion mobility spectrometry coupled to mass spectrometry (TIMS-MS) showed the MP-11 structural dependence of the charge state distribution and molecular ion forms with the starting pH conditions. The singly charged ( e.g. , [M] + , [M − 2H + NH 4 ] + , [M − H + Na] + and [M − H + K] + ) and doubly charged ( e.g. , [M + H] 2+ , [M − H + NH 4 ] 2+ , [M + Na] 2+ and [M + K] 2+ ) molecular ion forms were observed for all solvent conditions, although the structural heterogeneity ( e.g. , number of mobility bands) significantly varied with the pH value and ion form. The MP-11 dimer formation as a model for heme-protein protein interactions showed that dimer formation is favored toward more neutral pH and favored when assisted by salt bridges ( e.g. , NH 4 + , Na + and K + vs. H + ). Inspection of the dimer mobility profiles (2+ and 3+ charge states) showed a high degree of structural heterogeneity as a function of the solution pH and ion form; the observation of common mobility bands suggest that the different salt bridges can stabilize similar structural motifs. In addition, the salt bridge influence on the MP-11 dimer formations was measured using collision induced dissociation and showed a strong dependence with the type of salt bridge ( i.e. , a CE 50 of 10.0, 11.5, 11.8 and 13.0 eV was observed for [2M + H] 3+ , [2M − H + NH 4 ] 3+ , [2M + Na] 3+ and [2M + K] 3+ , respectively). Measurements of the dimer equilibrium constant showed that the salt bridge interactions increase the binding strength of the dimeric species. 

Since the release of the Oculus Rift CV1 in 2016, millionsof VR headsets have found their way into consumer homes.In this paper, we sought to understand what shifts have takenplace within the two years since consumer VR became avail-able. In this paper, we consider what can be learned aboutlong-term use of consumer VR through an analysis of dis-cussions in online forums devoted to VR. We gathered postsmade on the /r/Vive subreddit from the first two years after theHTC Vive’s release. We present the results from an in-depthqualitative analysis concerning immersion, presence, and sim-ulator sickness. Over time, as users moved from passive toactive, their attitudes and expectations towards immersion andsimulator sickness matured. Major trends of interest foundwere game design implementation and locomotion techniques.