New York University Abu Dhabi

A pseudo-Euclidean Novikov superalgebra A is a Novikov superalgebra endowed with a non-degenerate symmetric bilinear form ⟨,⟩ such that all left multiplication operators are ⟨,⟩-antisymmetric. In this case, the associated Lie superalgebra (A^-,⟨,⟩) is a flat pseudo-Euclidean Lie superalgebra. In this paper, we investigate the structure of pseudo-Euclidean Novikov superalgebras. In particular, we introduce a distinguished subclass, called Milnor superalgebras, and prove that any pseudo-Euclidean Novikov superalgebra whose two-sided ideal is non-degenerate belongs to this class. We provide a method for constructing pseudo-Euclidean Novikov superalgebras. We also introduce a double extension procedure for pseudo-Euclidean Novikov superalgebras and show that every such superalgebra with a degenerate two-sided ideal can be obtained via this method. Furthermore, we establish that any pseudo-Euclidean Novikov superalgebra is either a Milnor superalgebra or can be obtained by a sequence of double extensions starting from a Milnor superalgebra. As an application, we provide a complete classification of pseudo-Euclidean Novikov superalgebras of total dimension at most four.

This work presents a comprehensive numerical investigation of flashback phenomena in premixed hydrogen-air flames, focusing on the influence of bulk slit velocity, equivalence ratio, and porous media integration on flame stability. A stable laminar flame was first established at the stoichiometric equivalence ratio (phi = 1.0), providing a baseline for subsequent parametric analyses. Systematic flashback studies were then conducted by varying the bulk slit velocity to determine the critical flashback velocity at which the flame propagates upstream into the burner. The analysis was extended to fuel-lean mixtures (phi = 0.5-0.9) to characterize the dependence of flashback limits on equivalence ratio and to highlight the sensitivity of hydrogen flame stability to mixture strength. The results show a decreasing flashback velocity threshold with leaner mixtures, consistent with reductions in laminar burning velocity, flame temperature, and heat release rate. To mitigate flashback, the effect of integrating porous media at the burner inlet was numerically examined. The porous insert modifies local velocity profiles and thermal gradients, enhancing flame anchoring and preventing upstream flame propagation. Detailed analyses of flow and temperature fields demonstrate that porous media stabilize the flame front by suppressing near-wall velocity deficits and promoting heat recirculation near the flame base. These findings provide practical insight into flashback control mechanisms and contribute to the design of safer and more reliable hydrogen combustion systems.

Group centrality measures are a generalization of standard centrality, designed to quantify the importance of not just a single node (as is the case with standard measures) but rather that of a group of nodes. Some nodes may have an incentive to evade such measures, i.e., to hide their actual importance, in order to conceal their true role in the network. A number of studies have been proposed in the literature to understand how nodes can rewire the network in order to evade standard centrality, but no study has focused on group centrality to date. We close this gap by analyzing four group centrality measures: degree, closeness, betweenness, and GED-walk. We show that an optimal way to rewire the network can be computed efficiently given the former measure, but the problem is NP-complete given closeness and betweenness. Moreover, we empirically evaluate a number of hiding strategies, and show that an optimal way to hide from degree group centrality is also effective in practice against the other measures. Altogether, our results suggest that it is possible to hide from group centrality measures based solely on the local information available to the group members about the network topology.

In the Persian-Arabian Gulf, conservation is uniquely complicated by transboundary ecosystems, migratory species, and anthropogenic pressures in the world’s hottest sea. Additionally, inadequate infrastructure, inconsistent data standards, and limited data interoperability complicate cross-border collaboration for science where geopolitical sensitivities, institutional fragmentation, and uneven capacities create a complex trust environment that can constrain cross-border collaboration. We propose a model for biodiversity data diplomacy inspired by the decentralized, reciprocal, and adaptive mycelium-like networks. While existing bodies such as the Regional Organization for the Protection of the Marine Environment (ROPME) play a role, we outline further steps, including regional data frameworks, capacity building, and inclusive governance. Like other examples of science diplomacy in complex trust geopolitical regions, we see renewed opportunities in the Gulf for politically neutral, equitable, and peer-driven spaces for data sharing. Most importantly, Gulf states and non-state actors can seize the opportunity to establish shared scientific priorities as foundations for broader diplomatic engagement, ecological resilience, climate adaptation, and scientific leadership.

We report the multiwavelength properties of eROSITA Final Equatorial Depth Survey (eFEDS) J084222.9+001000 (hereafter ID830), a quasar at z = 3.4351, identified as the most X-ray luminous radio-loud quasar in the eFEDS field. ID830 shows a rest-frame 0.5-2 keV luminosity of log (L0.5-2kev/erg S-1)=46.20 +/- 0.12, with a steep X-ray photon index (Gamma = 2.43 +/- 0.21), and a significant radio counterpart detected with the Very Large Array FIRST 1.4 GHz and Very Large Array Sky Survey 3 GHz bands. The rest-frame UV to optical spectra from Sloan Digital Sky Survey and Subaru/MOIRCS J band show a dust-reddened quasar feature with A(V) = 0.39 +/- 0.08 mag, and the expected bolometric active galactic nuclei luminosity from the dust-extinction-corrected UV luminosity reaches L-bol,L-3000 & Aring; = (7.62 +/- 0.31) x 10(46) erg s(-1). We estimate a black hole mass of M-BH = (4.40 +/- 0.72) x 10(8) M-circle dot based on the Mg II lambda 2800 emission-line width, and Eddington ratios from the dust-extinction-corrected UV continuum luminosity and X-ray luminosity that reach lambda(Edd,UV) = 1.44 +/- 0.24 and lambda(Edd,X) = 12.8 +/- 3.9, respectively, both indicating super-Eddington accretion. ID830 shows a high ratio of UV to X-ray luminosities, alpha(OX) = -1.20 +/- 0.07 (or alpha(OX) = -1.42 +/- 0.07 after correcting for jet-linked X-ray excess), higher than quasars and little red dots in the super-Eddington phase with similar UV luminosities, with alpha(OX) < -1.8. Such a high alpha(OX) suggests the coexistence of a prominent radio jet and X-ray corona in this high-Eddington-accretion phase. We propose that ID830 may be in a transitional phase after an accretion burst, evolving from a super-Eddington to a sub-Eddington state, which could naturally describe the high alpha(OX).