Canonical bifurcation in higher derivative, higher spin, theories

We present a non-perturbative canonical analysis of the D=3 quadratic-curvature, yet ghost-free, model to exemplify a novel, "constraint bifurcation", effect. Consequences include a jump in excitation count: a linearized level gauge variable is promoted to a dynamical one in the full theory. We illustrate these results with their concrete perturbative counterparts. They are of course mutually consistent, as are perturbative findings in related models. A geometrical interpretation in terms of propagating torsion reveals the model's relation to an (improved) version of Einstein-Weyl gravity at the linearized level. Finally, we list some necessary conditions for triggering the bifurcation phenomenon in general interacting gauge systems.Comment: 10 pages, v2: typos corrected, v3: new title to reflect greatly expanded version, to appear in special issue of J Phys A (eds, M Vasiliev & M Gaberdiel

Molecular structure input on the web

A molecule editor, that is program for input and editing of molecules, is an indispensable part of every cheminformatics or molecular processing system. This review focuses on a special type of molecule editors, namely those that are used for molecule structure input on the web. Scientific computing is now moving more and more in the direction of web services and cloud computing, with servers scattered all around the Internet. Thus a web browser has become the universal scientific user interface, and a tool to edit molecules directly within the web browser is essential

Aluminum arsenide cleaved-edge overgrown quantum wires

We report conductance measurements in quantum wires made of aluminum arsenide, a heavy-mass, multi-valley one-dimensional (1D) system. Zero-bias conductance steps are observed as the electron density in the wire is lowered, with additional steps observable upon applying a finite dc bias. We attribute these steps to depopulation of successive 1D subbands. The quantum conductance is substantially reduced with respect to the anticipated value for a spin- and valley-degenerate 1D system. This reduction is consistent with disorder-induced, intra-wire backscattering which suppresses the transmission of 1D modes. Calculations are presented to demonstrate the role of strain in the 1D states of this cleaved-edge structure.Comment: Submitted to Applied Physics Letter

Evolutionary Multi-Objective Design of SARS-CoV-2 Protease Inhibitor Candidates

Computational drug design based on artificial intelligence is an emerging research area. At the time of writing this paper, the world suffers from an outbreak of the coronavirus SARS-CoV-2. A promising way to stop the virus replication is via protease inhibition. We propose an evolutionary multi-objective algorithm (EMOA) to design potential protease inhibitors for SARS-CoV-2's main protease. Based on the SELFIES representation the EMOA maximizes the binding of candidate ligands to the protein using the docking tool QuickVina 2, while at the same time taking into account further objectives like drug-likeliness or the fulfillment of filter constraints. The experimental part analyzes the evolutionary process and discusses the inhibitor candidates.Comment: 15 pages, 7 figures, submitted to PPSN 202

Supersymmetric black holes in 2D dilaton supergravity: baldness and extremality

We present a systematic discussion of supersymmetric solutions of 2D dilaton supergravity. In particular those solutions which retain at least half of the supersymmetries are ground states with respect to the bosonic Casimir function (essentially the ADM mass). Nevertheless, by tuning the prepotential appropriately, black hole solutions may emerge with an arbitrary number of Killing horizons. The absence of dilatino and gravitino hair is proven. Moreover, the impossibility of supersymmetric dS ground states and of nonextremal black holes is confirmed, even in the presence of a dilaton. In these derivations the knowledge of the general analytic solution of 2D dilaton supergravity plays an important role. The latter result is addressed in the more general context of gPSMs which have no supergravity interpretation. Finally it is demonstrated that the inclusion of non-minimally coupled matter, a step which is already nontrivial by itself, does not change these features in an essential way.Comment: 30 pages, LaTeX, v2: mayor revision (rearranged title, shortened abstract, revised introduction, inserted section from appendix to main text, added subsection with new material on non-SUGRA gPSMs, added clarifying remarks at some places, updated references); v3: corrected minor misprints, added note with a new referenc

Three-dimensional Models of Core-collapse Supernovae From Low-mass Progenitors With Implications for Crab

We present 3D full-sphere supernova simulations of non-rotating low-mass (~9 Msun) progenitors, covering the entire evolution from core collapse through bounce and shock revival, through shock breakout from the stellar surface, until fallback is completed several days later. We obtain low-energy explosions [~(0.5-1.0)x 10^{50} erg] of iron-core progenitors at the low-mass end of the core-collapse supernova (LMCCSN) domain and compare to a super-AGB (sAGB) progenitor with an oxygen-neon-magnesium core that collapses and explodes as electron-capture supernova (ECSN). The onset of the explosion in the LMCCSN models is modelled self-consistently using the Vertex-Prometheus code, whereas the ECSN explosion is modelled using parametric neutrino transport in the Prometheus-HOTB code, choosing different explosion energies in the range of previous self-consistent models. The sAGB and LMCCSN progenitors that share structural similarities have almost spherical explosions with little metal mixing into the hydrogen envelope. A LMCCSN with less 2nd dredge-up results in a highly asymmetric explosion. It shows efficient mixing and dramatic shock deceleration in the extended hydrogen envelope. Both properties allow fast nickel plumes to catch up with the shock, leading to extreme shock deformation and aspherical shock breakout. Fallback masses of <~5x10^{-3} Msun have no significant effects on the neutron star (NS) masses and kicks. The anisotropic fallback carries considerable angular momentum, however, and determines the spin of the newly-born NS. The LMCCSNe model with less 2nd dredge-up results in a hydrodynamic and neutrino-induced NS kick of >40 km/s and a NS spin period of ~30 ms, both not largely different from those of the Crab pulsar at birth.Comment: 47 pages, 27 figures, 6 tables; minor revisions, accepted by MNRA

An Exact Conformal Symmetry Ansatz on Kaluza-Klein Reduced TMG

Using a Kaluza-Klein dimensional reduction, and further imposing a conformal Killing symmetry on the reduced metric generated by the dilaton, we show an Ansatz that yields many of the known stationary axisymmetric solutions to TMG.Comment: 20 pages, 1 figure, v3: postprint, added one re

A Fast Alternative to Soft Lithography for the Fabrication of Organ-on-a-Chip Elastomeric-Based Devices and Microactuators

Organ-on-a-chip technology promises to revolutionize how pre-clinical human trials are conducted. Engineering an in vitro environment that mimics the functionality and architecture of human physiology is essential toward building better platforms for drug development and personalized medicine. However, the complex nature of these devices requires specialized, time consuming, and expensive fabrication methodologies. Alternatives that reduce design-to-prototype time are needed, in order to fulfill the potential of these devices. Here, a streamlined approach is proposed for the fabrication of organ-on-a-chip devices with incorporated microactuators, by using an adaptation of xurography. This method can generate multilayered, membrane-integrated biochips in a matter of hours, using low-cost benchtop equipment. These devices are capable of withstanding considerable pressure without delamination. Furthermore, this method is suitable for the integration of flexible membranes, required for organ-on-a-chip applications, such as mechanical actuation or the establishment of biological barrier function. The devices are compatible with cell culture applications and present no cytotoxic effects or observable alterations on cellular homeostasis. This fabrication method can rapidly generate organ-on-a-chip prototypes for a fraction of cost and time, in comparison to conventional soft lithography, constituting an interesting alternative to the current fabrication methods.C.O. and P.L.G. contributed equally to this work as co‐senior authors. This work was supported by Fundação para a Ciência e Tecnologia (FCT) and Doctoral Programme on Cellular and Molecular Biotechnology Applied to Health Sciences (BiotechHealth Programme; ref. PD/00016/2012), by Programa Operacional Potencial Humano (POPH), and SkinChip project (PTDC/BBB‐BIO/1889/2014). The work has been also financed by: 1) Fundo Europeu de Desenvolvimento (FEDER) Regional funds through the COMPETE 2020 – Operacional Programme for Competitiveness and Internationalization (POCI), Portugal 2020, and by Portuguese funds through FCT/Ministério da Ciência, Tecnologia e Inovação in the framework of the projects “Institute for Research and Innovation in Health Sciences” (POCI‐01‐0145‐FEDER‐007274), 3DChroMe (PTDC/BTM‐TEC/30164/2017); Norte Portugal Regional Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF) for projects NORTE‐01‐0145‐FEDER‐000029 and DOCnet (NORTE‐01‐0145‐FEDER‐000003). D.A.F. acknowledges FCT for his support through a FCT/BiotechHealth PhD Programme grant, ref. PD/BD/105976/2014. J.P.C. acknowledges funding from the European Structural and Investment funds through the Compete Programme (Grant #: LISBOA‐01‐0145‐FEDER‐016405) and from National funds through FCT (SAICTPAC/0019/2015) via the research project POINT4PAC, and FCT funding through INESC MN (Unidade ID 5367). The authors would also like to thank: Jorge Ferreira (Chromosome Instability Group, i3S/IBMC) for granting access to the plasma cleaner equipment and for the insightful scientific support; i3S Scientific Platform (Biointerfaces and Nanotechnology core facility, i3S/INEB), member of the national infrastructure PPBI – Portuguese Platform of Bioimaging (PPBI‐POCI‐01‐0145‐FEDER‐022122), in particular Maria Lázaro for support and access to the SP5 confocal microscope; Aureliana Sousa (Biofabrication Group at i3S/INEB) for scientific support and discussion; Dina Leitão (Centro Hospitalar e Universitário São João) for providing access to the normal gastric mucosa specimens; Celso Reis for kindly providing the antibody against Mucin‐1. C.O. and P.L.G. contributed equally to this work as co-senior authors. This work was supported by Funda??o para a Ci?ncia e Tecnologia (FCT) and Doctoral Programme on Cellular and Molecular Biotechnology Applied to?Health Sciences (BiotechHealth Programme; ref.?PD/00016/2012),?by Programa Operacional Potencial Humano (POPH), and SkinChip project (PTDC/BBB-BIO/1889/2014). The work has been also financed by: 1) Fundo Europeu de Desenvolvimento (FEDER) Regional funds through the COMPETE 2020 ? Operacional Programme for Competitiveness and Internationalization (POCI), Portugal 2020, and by Portuguese funds through FCT/Minist?rio da Ci?ncia, Tecnologia e Inova??o in the framework of the projects ?Institute for Research and Innovation in Health Sciences? (POCI-01-0145-FEDER-007274), 3DChroMe (PTDC/BTM-TEC/30164/2017); Norte Portugal Regional Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF) for projects NORTE-01-0145-FEDER-000029 and DOCnet (NORTE-01-0145-FEDER-000003). D.A.F. acknowledges FCT for his support through a FCT/BiotechHealth PhD Programme grant, ref. PD/BD/105976/2014. J.P.C. acknowledges funding from the European Structural and Investment funds through the Compete Programme (Grant #: LISBOA-01-0145-FEDER-016405) and from National funds through FCT (SAICTPAC/0019/2015) via the research project POINT4PAC, and FCT funding through INESC MN (Unidade ID 5367). The authors would also like to thank: Jorge Ferreira (Chromosome Instability Group, i3S/IBMC) for granting access to the plasma cleaner equipment and for the insightful scientific support; i3S Scientific Platform (Biointerfaces and Nanotechnology core facility, i3S/INEB), member of the national infrastructure PPBI ? Portuguese Platform of Bioimaging (PPBI-POCI-01-0145-FEDER-022122), in particular Maria L?zaro for support and access to the SP5 confocal microscope; Aureliana Sousa (Biofabrication Group at i3S/INEB) for scientific support and discussion; Dina Leit?o (Centro Hospitalar e Universit?rio S?o Jo?o) for providing access to the normal gastric mucosa specimens; Celso Reis for kindly providing the antibody against Mucin-1