COVID-19 and liver disease: mechanistic and clinical perspectives

Our understanding of the hepatic consequences of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and its resultant coronavirus disease 2019 (COVID-19) has evolved rapidly since the onset of the pandemic. In this Review, we discuss the hepatotropism of SARS-CoV-2, including the differential expression of viral receptors on liver cell types, and we describe the liver histology features present in patients with COVID-19. We also provide an overview of the pattern and relevance of abnormal liver biochemistry during COVID-19 and present the possible underlying direct and indirect mechanisms for liver injury. Furthermore, large international cohorts have been able to characterize the disease course of COVID-19 in patients with pre-existing chronic liver disease. Patients with cirrhosis have particularly high rates of hepatic decompensation and death following SARS-CoV-2 infection and we outline hypotheses to explain these findings, including the possible role of cirrhosis-associated immune dysfunction. This finding contrasts with outcome data in pharmacologically immunosuppressed patients after liver transplantation who seem to have comparatively better outcomes from COVID-19 than those with advanced liver disease. Finally, we discuss the approach to SARS-CoV-2 vaccination in patients with cirrhosis and after liver transplantation and predict how changes in social behaviours and clinical care pathways during the pandemic might lead to increased liver disease incidence and severity. © 2021, Springer Nature Limited

Occurrence of a chiral-like pair band and a six-nucleon noncollective oblate isomer in ¹²⁰I

We report for the first time two distinctive features in the odd–odd nucleus 120 I: a pair of doublet bands and a high-spin isomer built on the πh11/2νh11/2 configuration. For producing the excited states of 120 I, a fusion-evaporation reaction 118 Sn( 6 Li, 4n) at E =lab48 MeV was employed. The beam was provided by the 14UD tandem accelerator of the Heavy Ion Accelerator Facility at the Australian National University. The observed doublet structure built on the positive-parity states is the first case and unique in isotopes with Z=53 . The emerging properties are indicative of the known chiral characteristics, leading to a doubling of states for the πh11/2νh11/2 configuration. In contrast, the high-spin isomer with a half-life of 49(2) ns at spin-parity Jπ=25+ can be explained in terms of a noncollective oblate structure with the full alignment of six valence nucleons outside the 114 Sn core: three protons (g7/2)1(d5/2)1(h11/2)1 and three neutrons (h11/2)3 . This is an outstanding case that reveals a pure single-particle structure consisting of equal numbers of valence protons and neutrons outside the semi-double shell closure of 114 Sn with Z=50 and N=64 .Dr. C. Yuan acknowledges the National Natural Science Foundation of China (11775316

Feedback Vertex Sets in Tournaments

We study combinatorial and algorithmic questions around minimal feedback vertex sets in tournament graphs. On the combinatorial side, we derive strong upper and lower bounds on the maximum number of minimal feedback vertex sets in an n-vertex tournament. We prove that every tournament on n vertices has at most 1.6740^n minimal feedback vertex sets, and that there is an infinite family of tournaments, all having at least 1.5448^n minimal feedback vertex sets. This improves and extends the bounds of Moon (1971). On the algorithmic side, we design the first polynomial space algorithm that enumerates the minimal feedback vertex sets of a tournament with polynomial delay. The combination of our results yields the fastest known algorithm for finding a minimum size feedback vertex set in a tournament

Stability analysis of f(R)-AdS black holes

We study the stability of f(R)-AdS (Schwarzschild-AdS) black hole obtained from f(R) gravity. In order to resolve the difficulty of solving fourth order linearized equations, we transform f(R) gravity into the scalar-tensor theory by introducing two auxiliary scalars. In this case, the linearized curvature scalar becomes a dynamical scalaron, showing that all linearized equations are second order. Using the positivity of gravitational potentials and S-deformed technique allows us to guarantee the stability of f(R)-AdS black hole if the scalaron mass squared satisfies the Breitenlohner-Freedman bound. This is confirmed by computing quasinormal frequencies of the scalaron for large f(R)-AdS black hole.Comment: 17 pages, 1 figure, version to appear in EPJ

Determining risk factors for mortality in liver transplant patients with COVID-19

We read with great interest the Correspondence from Bhoori and colleagues1 describing the effect of coronavirus disease 2019 (COVID-19) on their centre's adult liver transplant population.1 Within their cohort of over 150 transplant recipients, the authors identified six patients with COVID-19, including three resulting deaths. Each of those who died was transplanted over 10 years previously and were older than 65 years, male, overweight, and had hypertension and diabetes. The authors speculated as to whether these characteristics might be major risk factors for mortality

Opto-mechanical measurement of micro-trap via nonlinear cavity enhanced Raman scattering spectrum

High-gain resonant nonlinear Raman scattering on trapped cold atoms within a high-fineness ring optical cavity is simply explained under a nonlinear opto-mechanical mechanism, and a proposal using it to detect frequency of micro-trap on atom chip is presented. The enhancement of scattering spectrum is due to a coherent Raman conversion between two different cavity modes mediated by collective vibrations of atoms through nonlinear opto-mechanical couplings. The physical conditions of this technique are roughly estimated on Rubidium atoms, and a simple quantum analysis as well as a multi-body semiclassical simulation on this nonlinear Raman process is conducted.Comment: 7 pages, 2 figure

Dynamic Vortex Phases and Pinning in Superconductors with Twin Boundaries

We investigate the pinning and driven dynamics of vortices interacting with twin boundaries using large scale molecular dynamics simulations on samples with near one million pinning sites. For low applied driving forces, the vortex lattice orients itself parallel to the twin boundary and we observe the creation of a flux gradient and vortex free region near the edges of the twin boundary. For increasing drive, we find evidence for several distinct dynamical flow phases which we characterize by the density of defects in the vortex lattice, the microscopic vortex flow patterns, and orientation of the vortex lattice. We show that these different dynamical phases can be directly related to microscopically measurable voltage - current V(I) curves and voltage noise. By conducting a series of simulations for various twin boundary parameters we derive several vortex dynamic phase diagrams.Comment: 5 figures, to appear in Phys. Rev.

Decay properties of high-spin isomers and other structures in Sb121 and Sb123

High-spin states populated in the decay of microsecond isomers in the transitional nuclei Sb121 and Sb123 have been investigated in detail in several experiments using γ-ray and electron spectroscopy. The nuclei were formed using multinucleon transfer and fusion-fission reactions with Xe136 beams and also using the Sn120(Li7,α2n)Sb121 and Sn122(Li7,α2n)Sb123 incomplete-fusion reactions. Isomeric half-lives ranging from several nanoseconds to a few hundred microseconds were determined by means of conventional decay curve analyses, whereas very short-lived isomers (T1/2~1 ns) were identified using the generalized centroid-shift method. A number of new transitions were observed, including a branch through spherical states from the 19/2+ member of the 9/2+ deformed band in Sb121, in competition with the main decay path through the rotational band. This is attributed to mixing between the 19/2+ band member and a 19/2+ spherical state. Both levels are predicted to coincide approximately in energy in Sb121. The fact that a 25/2+ isomer occurs for A=121 and the lighter isotopes, while a 23/2+ isomer is observed for A=123-131 is explained through a multistate mixing calculation, taking into account the gradual shift of the 2d5/2 and 1g7/2 proton orbitals and the change in proton-neutron effective interactions from an attractive particle-particle type in the lower part of the shell to a repulsive particle-hole type with increasing the neutron number toward the N=82 shell closure. The observed enhancement of the B(E2;19/2-→15/2-) values in Sb121 and Sb123 over the B(E2;7-→5-) values in the corresponding Sn cores is discussed in terms of configuration mixing between spherical and deformed states