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Cover page of A multiscale model for El Niño complexity

A multiscale model for El Niño complexity

(2022)

El Niño-Southern Oscillation (ENSO) exhibits diverse characteristics in spatial pattern, peak intensity, and temporal evolution. Here we develop a three-region multiscale stochastic model to show that the observed ENSO complexity can be explained by combining intraseasonal, interannual, and decadal processes. The model starts with a deterministic three-region system for the interannual variabilities. Then two stochastic processes of the intraseasonal and decadal variation are incorporated. The model can reproduce not only the general properties of the observed ENSO events, but also the complexity in patterns (e.g., Central Pacific vs. Eastern Pacific events), intensity (e.g., 10–20 year reoccurrence of extreme El Niños), and temporal evolution (e.g., more multi-year La Niñas than multi-year El Niños). While conventional conceptual models were typically used to understand the dynamics behind the common properties of ENSO, this model offers a powerful tool to understand and predict ENSO complexity that challenges our understanding of the twenty-first century ENSO.

Cover page of Cultivating one health antibiotic stewards to bridge translational science gaps in the global action plan.

Cultivating one health antibiotic stewards to bridge translational science gaps in the global action plan.

(2022)

Scientific evidence for the urgency of curbing the emergence and spread of antimicrobial resistance is incontrovertible. Yet, the translation of knowledge into effective design and implementation of action plans is hampered by gaps in perception, attitudes and practices in the human health, agriculture, and environmental sectors. To fill these gaps in regions where the disease burden attributable to antimicrobial resistance is heaviest, a cadre of One Health Stewards equipped with strategies to translate and meld global and local evidence for knowledge dissemination is deemed necessary. This opinion articulates a case for cultivating and deploying One Health Antibiotic Stewards according to specific actions within the environmental context of antibiotic resistance.

Cover page of Does conflict of interest affect the reported fusion rates of bone graft substitutes and extenders?

Does conflict of interest affect the reported fusion rates of bone graft substitutes and extenders?

(2022)

Background

Bone graft extenders are being used more in spine surgery as a substitute for iliac crest bone graft. However, potential conflict of interest could impact average fusion rates. The purpose of this study was to evaluate whether fusion rates reported in the literature were different in papers evaluating bone graft substitutes and extenders when there was potential conflict of interest versus no potential conflict of interest.

Methods

Pubmed was searched for studies evaluating fusion rates when bone graft extenders including demineralized bone matrix, hydroxyapatite, and tricalcium sulfate were used. Studies were screened for one or two level fusions and for degenerative spinal conditions. The average fusion rates of subgroups were compared using unpaired Student's t-tests.

Results

1928 studies were evaluated. 86 studies were included in the study. The fusion rates varied from 4 to 100%. There were 24 studies with a potential conflict of interest and 62 studies with no conflict of interest. The average fusion rate of all the studies was 84.63% with standard deviation of 18.33%. The average fusion rates of those studies with conflict of interest was 80.93% versus 86.06% without conflict of interest. This was not statistically significant (p>0.07). The average fusion rate of studies evaluated by CT scan was 79.8% versus 87.9% without CT. The average fusion rate of studies that employed an independent reviewer to evaluate the fusion was 82.61% versus 85.63% for studies with no independent reviewer.

Conclusion

There is a great variability in the reported fusion rates of bone graft extenders. Counter to expectations, average fusion rates were lower in the studies where there was a potential conflict of interest. The use of CT scans and an independent reviewer seem to account for the lower reported fusion rates, and may be a means of negating the potential conflicts of interest in fusion studies.

Level of evidence

2.

Cover page of Structure and conformational dynamics of Clostridioides difficile toxin A.

Structure and conformational dynamics of Clostridioides difficile toxin A.

(2022)

Clostridioides difficile toxin A and B (TcdA and TcdB) are two major virulence factors responsible for diseases associated with C. difficile infection (CDI). Here, we report the 3.18-Å resolution crystal structure of a TcdA fragment (residues L843-T2481), which advances our understanding of the complete structure of TcdA holotoxin. Our structural analysis, together with complementary single molecule FRET and limited proteolysis studies, reveal that TcdA adopts a dynamic structure and its CROPs domain can sample a spectrum of open and closed conformations in a pH-dependent manner. Furthermore, a small globular subdomain (SGS) and the CROPs protect the pore-forming region of TcdA in the closed state at neutral pH, which could contribute to modulating the pH-dependent pore formation of TcdA. A rationally designed TcdA mutation that trapped the CROPs in the closed conformation showed drastically reduced cytotoxicity. Taken together, these studies shed new lights into the conformational dynamics of TcdA and its roles in TcdA intoxication.

Roller Coaster in a Flatland: Magnetoresistivity in Eu-Intercalated Graphite

(2022)

Novel phenomena in magnetically intercalated graphite have been the subject of much research, pioneered and promoted by M. S. and G. Dresselhaus and many others in the 1980s. Among the most enigmatic findings of that era was the dramatic, roller-coaster-like behavior of the magnetoresistivity in a EuC6 compound, in which magnetic Eu2+ ions form a triangular lattice that is commensurate to graphite honeycomb planes. In this study, we provide a long-awaited microscopic explanation of this behavior, demonstrating that the resistivity of EuC6 is dominated by spin excitations in Eu planes and their highly nontrivial evolution with the magnetic field. Together with our theoretical analysis, the present study showcases the power of the synthetic 2D materials as a source of potentially significant insights into the nature of exotic spin excitations.

Cover page of Patent Performativity

Patent Performativity

(2022)

Patent law remains stubbornly undertheorized; we have surprisingly little understanding of the social role of patents or its implications. To help address this deficit, this paper examines patents as performatives, that is, as social assemblages that enact what they disclose, and that create their own social facts. To demonstrate patent performativity, I briefly trace the development of performative concepts, from Austinian declarations, through Butlerian enactments, to Barnesian social constitutives. I then indicate how patents function in each of these respective modes of performativity, first as performative speech acts, then as normative inscriptions, and ultimately as mechanisms of social fabrication. Drawing on these observations, I identify what it means to perform patents, and suggest some practical and doctrinal implications of patent performativity, particularly for the “gender gap” that is manifest in the patent system.