1,502 research outputs found
Power operations in the Stolz-Teichner program
The Stolz–Teichner program proposes a deep connection between geometric field theories and certain cohomology theories. We extend this connection by developing a theory of geometric power operations for geometric field theories restricted to closed bordisms. These operations satisfy relations analogous to the ones exhibited by their homotopical counterparts. We also provide computational tools to identify the geometrically defined operations with the usual power operations on complexified equivariant K–theory. Further, we use the geometric approach to construct power operations for complexified equivariant elliptic cohomology
Fly-by-light flight control system technology development plan
The results of a four-month, phased effort to develop a Fly-by-Light Technology Development Plan are documented. The technical shortfalls for each phase were identified and a development plan to bridge the technical gap was developed. The production configuration was defined for a 757-type airplane, but it is suggested that the demonstration flight be conducted on the NASA Transport Systems Research Vehicle. The modifications required and verification and validation issues are delineated in this report. A detailed schedule for the phased introduction of fly-by-light system components has been generated. It is concluded that a fiber-optics program would contribute significantly toward developing the required state of readiness that will make a fly-by-light control system not only cost effective but reliable without mitigating the weight and high-energy radio frequency related benefits
Conceptual and Methodological Problems with Comparative Work on Artificial Language Learning
Several theoretical proposals for the evolution of language have sparked a renewed search for comparative data on human and non-human animal computational capacities. However, conceptual confusions still hinder the field, leading to experimental evidence that fails to test for comparable human competences. Here we focus on two conceptual and methodological challenges that affect the field generally: 1) properly characterizing the computational features of the faculty of language in the narrow sense; 2) defining and probing for human language-like computations via artificial language learning experiments in non-human animals. Our intent is to be critical in the service of clarity, in what we agree is an important approach to understanding how language evolved
Averaging Property of Wedge Product and Naturality in Discrete Exterior Calculus
In exterior calculus on smooth manifolds, the exterior derivative and wedge
product are natural with respect to smooth maps between manifolds, that is,
these operations commute with pullback. In discrete exterior calculus (DEC),
simplicial cochains play the role of discrete forms, the coboundary operator
serves as the discrete exterior derivative, and the antisymmetrized cup product
provides a discrete wedge product. We show that these discrete operations in
DEC are natural with respect to abstract simplicial maps. A second contribution
is a new averaging interpretation of the discrete wedge product in DEC. We also
show that this wedge product is the same as Wilson's cochain product defined
using Whitney and de Rham maps.Comment: arXiv admin note: substantial text overlap with arXiv:2104.10277.
Note from authors in response to arXiv admin note: The material in this
submission was split off from arXiv:2104.10277 and version 2 of
arXiv:2104.10277 does not contain the material in this submission. This
revision includes material about cochain product using Whitney forms and
connection to C-infinity algebra
Learning from error: leading a culture of safety
A recent shift towards more collective leadership in the NHS can help to achievea culture of safety, particularly through encouraging frontline staff to participateand take responsibility for improving safety through learning from error andnear misses. Leaders must ensure that they provide psychological safety,organizational fairness and learning systems for staff to feel confident in raisingconcerns, that they have the autonomy and skills to lead continual improvement,and that they have responsibility for spreading this learning within and acrossorganizations
A co-design approach to service improvement resulted in teams exhibiting characteristics that support innovation
This paper analyzes a subset of data from a project that sought to transfer knowledge and skills around design led approaches for service improvement to teams working in Health and Social Care in the United Kingdom. Through this analysis the authors sought to understand the range of responses that individual participants had to undertaking service improvement work in a design led project. This was a qualitative study using interviews to gain reflections from participants. These interview transcripts were analyzed using framework analysis. Participants were recruited from three disparate organizations, a public health team of a local authority, a mental health charity and a UK National Health Service mental health initiative. Six main themes were identified, namely; design practice, collaborative working, creating an environment for innovation, team skills and attitudes and transfer of knowledge. The findings suggest that the design approach can contribute to a range of factors that have been identified as valuable for innovative teams. The paper adds to the evidence base and supports further exploration of the use of design in Service improvement and wider innovation endeavours
Contribution of hydrogen sulfide to the control of coronary blood flow
This study examined the mechanisms by which H2S modulates coronary microvascular resistance and myocardial perfusion at rest and in response to cardiac ischemia. Experiments were conducted in isolated coronary arteries and in open-chest anesthetized dogs. We found that the H2S substrate L-cysteine (1-10 mM) did not alter coronary tone of isolated arteries in vitro or coronary blood flow in vivo. In contrast, intracoronary (ic) H2S (0.1-3 mM) increased coronary flow from 0.49 ± 0.08 to 2.65 ± 0.13 ml/min/g (P□0.001). This increase in flow was unaffected by inhibition of Kv channels with 4-aminopyridine (P=0.127) but was attenuated (0.23 ± 0.02 to 1.13 ± 0.13 ml/min/g) by the KATP channel antagonist glibenclamide (P□0.001). Inhibition of NO synthesis (L-NAME) did not attenuate coronary responses to H2S. Immunohistochemistry revealed expression of cystathionine gamma-lyase (CSE), an endogenous H2S enzyme, in myocardium. Inhibition of CSE with β-cyano-L-alanine (10 µM) had no effect on baseline coronary flow or responses to a 15 sec coronary occlusion (P=0.82). These findings demonstrate that exogenous H2S induces potent, endothelial-independent dilation of the coronary microcirculation predominantly through the activation of KATP channels, however, our data do not support a functional role for endogenous H2S in the regulation of coronary microvascular resistance
Intracoronary glucagon-like peptide 1 preferentially augments glucose uptake in ischemic myocardium independent of changes in coronary flow
We examined the acute dose-dependent effects of intracoronary glucagon-like peptide (GLP)-1 (7-36) on coronary vascular tone, cardiac contractile function and metabolism in normal and ischemic myocardium. Experiments were conducted in open chest, anesthetized dogs at coronary perfusion pressures (CPP) of 100 and 40 mmHg before and during intracoronary GLP-1 (7-36) infusion (10 pmol/L to 1 nmol/L). Isometric tension studies were also conducted in isolated coronary arteries. Cardiac and coronary expression of GLP-1 receptors (GLP-1R) was assessed by Western blot and immunohistochemical analysis. GLP-1R was present in the myocardium and the coronary vasculature. The tension of intact and endothelium-denuded coronary artery rings was unaffected by GLP-1. At normal perfusion pressure (100 mmHg), intracoronary GLP-1 (7-36) (targeting plasma concentration 10 pmol/L to 1 nmol/L) did not affect blood pressure, coronary blood flow or myocardial oxygen consumption (MVO(2)); however, there were modest reductions in cardiac output and stroke volume. In untreated control hearts, reducing CPP to 40 mmHg produced marked reductions in coronary blood flow (0.50 ± 0.10 to 0.17 ± 0.03 mL/min/g; P < 0.001) and MVO(2) (27 ± 2.3 to 15 ± 2.7 μL O(2)/min/g; P < 0.001). At CPP = 40 mmHg, GLP-1 had no effect on coronary blood flow, MVO(2) or regional shortening, but dose-dependently increased myocardial glucose uptake from 0.11 ± 0.02 μmol/min/g at baseline to 0.17 ± 0.04 μmol/min/g at 1 nmol/L GLP-1 (P < 0.001). These data indicate that acute, intracoronary administration of GLP-1 (7-36) preferentially augments glucose metabolism in ischemic myocardium, independent of effects on cardiac contractile function or coronary blood flow
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