Respiratory infections

A new European Respiratory Review series explores respiratory infections https://bit.ly/3A5eN3

Optimal stability and instability for near-linear Hamiltonians

In this paper, we will prove a very general result of stability for perturbations of linear integrable Hamiltonian systems, and we will construct an example of instability showing that both our result and our example are optimal. Moreover, in the same spirit as the notion of KAM stable integrable Hamiltonians, we will introduce a notion of effectively stable integrable Hamiltonians, conjecture a characterization of these Hamiltonians and show that our result prove this conjecture in the linear case

International Respiratory Infections Society COVID Research Conversations: Podcast 2 with Dr. Michael S. Niederman and Dr. Edward J. Schenck

Section(s) Topics 1–4 Introductions 5 COVID-19 in New York City 6–7 Telemedicine, long-term sequelae 8 Development of a multi-disciplinary ICU team 9–10 Treatment of ARDS, COVID-19 pathogenesis 11–12 Prioritizing treatment at research 13 Challenges in tracing the natural history of severe COVID-19 14–15 Experience with mechanically ventilated patients; non-pulmonary organ failure 16–17 Mapping COVID-19 trajectories by SOFA score 18–20 Findings: additive organ dysfunction, improving vs. worsening trajectory 21 ARDS therapeutic approaches 22 Clinical trials involving Cornell 23–25 Lessons learned: patient care, research, education, caring for critical care workers 26–30 2021 predictions: improved therapies and research, endemic COVID-19, vaccines 31–33 Prioritizing research projects at Cornell 34–38 Explanations for caseload reduction 39–43 Thanks and sign-of

Stability transitions for axisymmetric relative equilibria of Euclidean symmetric Hamiltonian systems

In the presence of noncompact symmetry, the stability of relative equilibria under momentum-preserving perturbations does not generally imply robust stability under momentum-changing perturbations. For axisymmetric relative equilibria of Hamiltonian systems with Euclidean symmetry, we investigate different mechanisms of stability: stability by energy-momentum confinement, KAM, and Nekhoroshev stability, and we explain the transitions between these. We apply our results to the Kirchhoff model for the motion of an axisymmetric underwater vehicle, and we numerically study dissipation induced instability of KAM stable relative equilibria for this system.Comment: Minor revisions. Typographical errors correcte

Double exponential stability of quasi-periodic motion in Hamiltonian systems

We prove that generically, both in a topological and measure-theoretical sense, an invariant Lagrangian Diophantine torus of a Hamiltonian system is doubly exponentially stable in the sense that nearby solutions remain close to the torus for an interval of time which is doubly exponentially large with respect to the inverse of the distance to the torus. We also prove that for an arbitrary small perturbation of a generic integrable Hamiltonian system, there is a set of almost full positive Lebesgue measure of KAM tori which are doubly exponentially stable. Our results hold true for real-analytic but more generally for Gevrey smooth systems

The Slippery Slope of MIS Academia: A Discussion of the Quest for Relevance in Our Discipline

The MIS discipline faces the need to periodically re-establish its relevance to both academics and practitioners. Evolving technology forces our discipline to change at a rate far exceeding that of other business disciplines. In the workplace, rapidly evolving IT management issues and technologies have led corporations to manage technical employees differently than other employees. In academia, however, MIS faculty are faced with the same expectations as other business faculty. The current model of MIS as an academic discipline has many issues that make staying current and relevant very difficult. The result is that MIS research and teaching lag practice. One might argue that as the field matures, we are falling further behind. This paper is the outcome of a panel discussion held during the 2006 Americas Conference on Information Systems in Acapulco, Mexico. The panel discussed the assertions that MIS is on a Slippery Slope that threatens our existence as a business discipline and that our current model encourages irrelevance, both in research and in teaching. Panel members were asked to share their views on five questions relative to the Slippery Slope from their unique perspectives

Effects of the protonophore carbonyl-cyanide m-chlorophenylhydrazone on intracytoplasmic membrane assembly in Rhodobacter sphaeroides

AbstractThe effect of carbonyl-cyanide m-chlorophenyl-hydrazone (CCCP) on intracytoplasmic membrane (ICM) assembly was examined in the purple bacterium Rhodobacter sphaeroides. CCCP blocks generation of the electrochemical proton gradient required for integral membrane protein insertion. ICM formation was induced for 8h, followed by a 4-h exposure to CCCP. Measurements of fluorescence induction/relaxation kinetics showed that CCCP caused a diminished quantum yield, a cessation in expansion of the functional absorption cross-section and a 4- to 10-fold slowing in the electron transfer turnover rate. ICM vesicles (chromatophores) and an upper-pigmented band (UPB) containing ICM growth initiation sites, were isolated and subjected to clear-native electrophoresis. Proteomic analysis of the chromatophore gel bands indicated that CCCP produced a 2.7-fold reduction in spectral counts in the preferentially assembled light-harvesting 2 (LH2) antenna, while the RC-LH1 complex, F1FO-ATPase and pyridine nucleotide transhydrogenase decreased by 1.7–1.9-fold. For 35 soluble enzymes, the ratio of 0.99 for treated/control proteins demonstrated that protein synthesis was unaffected by CCCP, suggesting that the membrane complex decline arose from the turnover of unassembled apoproteins. In the UPB fraction, an ~2-fold accumulation was observed for the preprotein translocase SecY, the SecA translocation ATPase, SecD and SecF insertion components, and chaperonins DnaJ and DnaK, consistent with the possibility that these factors, which act early in the assembly process, have accumulated in association with nascent polypeptides as stabilized assembly intermediates