Managing the Three-Party Entanglement Challenge

We introduce the challenges of multi-party quantum entanglement and explain a recent success in learning to take its measure. Given the widely accepted reputation of entanglement as a counter-intuitive feature of quantum theory, we first describe pure-state entanglement itself. We restrict attention to multi-party qubit states. Then we introduce the features that have made it challenging for several decades to extend an entanglement measure beyond the 2-qubit case of Bell states. We finish with a description of the current understanding that solves the 3-qubit entanglement challenge. This necessarily takes into account the fundamental division of the 3-qubit state space into two completely independent sectors identified with the so-called GHZ and $W$ states.Comment: 16 pages and 3 figure

Sudden Death of Genuine Tripartite Entanglement

Entanglement sudden death (ESD) is a dynamical physical process [Yu and Eberly, Science 323, 598 (2009)]. It occurs when entanglement is able to vanish abruptly, i.e., with a discontinuous slope as a function of time, even though the entangled qubits themselves evolve steadily and analytically. Two-qubit ESD has been well-described and multiply observed, but it remains a mystery. That is, it has not been possible to identify any initial condition under which a state's dynamics can be confidently predicted to evolve to ESD. This challenge has been frustrated by the lack of a quantitative measure of genuine entanglement even for pure-state systems as small as three qubits. Now, with the help of a newly discovered three-qubit measure [Xie and Eberly, Phys. Rev. Lett 127, 040403 (2021)], and by bringing convex-roof construction and Legendre transforms into play, we are able to describe the mixed-state ESD dynamics of a three-qubit system. An unexpected bonus of this advance is the identification of a condition under which ESD can reliably be anticipated.Comment: 5 pages, 3 figure

Flux density measurements for 32 pulsars in the 20 cm band

Flux density measurements provide fundamental observational parameters that describe a pulsar. In the current pulsar catalogue, 27% of radio pulsars have no flux density measurement in the 20 cm observing band. Here, we present the first measurements of the flux densities in this band for 32 pulsars observed using the Parkes radio telescope and provide updated pulse profiles for these pulsars. We have used both archival and new observations to make these measurements. Various schemes exist for measuring flux densities. We show how the flux densities measured vary between these methods and how the presence of radio-frequency-interference will bias flux density measurementsComment: Accepted by RA

The relative importance of physicochemical factors and crustacean zooplankton as determinants of rotifer density and species distribution in lakes adjacent to the Yangtze River, China

The planktonic community of freshwater Rotifera in 27 subtropical lakes was studied to assess the relative importance of physicochemical factors and crustacean zooplankton as determinants of rotifer density and species distribution. Factor analysis and multiple linear regressions showed that 21.9% and 29.9% of the variance in rotifer density was explained by physicochemical factors and crustaceans, respectively. Larger rotifer density was possible in shallower lakes with higher concentration of inorganic nitrogen and less herbivorous crustaceans such as Sinocalanus dorrii and Daphnia. Redundancy analysis showed that the variances of rotifer species distribution explained by crustaceans and physicochemical factors were 26.9% and 31.0%, respectively. Further analysis demonstrated that the variances explained by pure crustaceans and pure physicochemical factors were 12.5% and 16.6%, respectively. However, these two percentages were not statistically different. Rotifer species distribution was strongly associated with Chl a and Moina micrura. Their coexistence with Crustaceans seemed to be determined by their defense against potential predators and competitors. (C) 2009 Elsevier GmbH. All rights reserved

Crustacean zooplankton distribution patterns and their biomass as related to trophic indicators of 29 shallow subtropical lakes

A comparative limnological study was carried out to present a snapshot of crustacean zooplankton communities and their relations to environmental factors to test whether there is a consistent relationship between crustacean biomass and trophic indicators among lake groups with similar trophic conditions. The study lakes showed a wide range of trophic status, with total phosphorus (TP) ranging from 0.008 to 1.448mgL(-1), and chlorophyll a from 0.7 to 146.1 mu g L-1, respectively. About 38 species of Crustacea were found, of which Cladocera were represented by 25 taxa (20 genera), and Copepoda by 13 taxa (I I genera). The most common and dominant species were Bosmina coregoni, Moina micrura, Diaphanosoma brachyurum, Cyclops vicinus, Thermocyclops taihokuensis, Mesocyclops notius and Sinocalanus dorrii. Daphnia was rare in abundance. Canonical correspondence analysis showed that except for four species (D. hyalina, S. dorrii, C. vicinus and M. micrura), almost all the dominant species had the same preference for environmental factors. Temperature, predatory cyclopoids and planktivorous fishes seem to be the key factors determining species distribution. TP was a relatively better trophic indicator than chlorophyll a to predict crustacean biomass. Within the three groups of lakes, however, there was no consistent relationship between crustacean biomass and trophic indicators. The possible reason might be that top-down and bottom-up control on crustaceans vary with lake trophic state. The lack of significant negative correlation between crustacean biomass and chlorophyll a suggests that there was little control of phytoplankton biomass by macrozooplankton in these shallow subtropical lakes. (c) 2007 Elsevier GmbH. All rights reserved.A comparative limnological study was carried out to present a snapshot of crustacean zooplankton communities and their relations to environmental factors to test whether there is a consistent relationship between crustacean biomass and trophic indicators among lake groups with similar trophic conditions. The study lakes showed a wide range of trophic status, with total phosphorus (TP) ranging from 0.008 to 1.448mgL(-1), and chlorophyll a from 0.7 to 146.1 mu g L-1, respectively. About 38 species of Crustacea were found, of which Cladocera were represented by 25 taxa (20 genera), and Copepoda by 13 taxa (I I genera). The most common and dominant species were Bosmina coregoni, Moina micrura, Diaphanosoma brachyurum, Cyclops vicinus, Thermocyclops taihokuensis, Mesocyclops notius and Sinocalanus dorrii. Daphnia was rare in abundance. Canonical correspondence analysis showed that except for four species (D. hyalina, S. dorrii, C. vicinus and M. micrura), almost all the dominant species had the same preference for environmental factors. Temperature, predatory cyclopoids and planktivorous fishes seem to be the key factors determining species distribution. TP was a relatively better trophic indicator than chlorophyll a to predict crustacean biomass. Within the three groups of lakes, however, there was no consistent relationship between crustacean biomass and trophic indicators. The possible reason might be that top-down and bottom-up control on crustaceans vary with lake trophic state. The lack of significant negative correlation between crustacean biomass and chlorophyll a suggests that there was little control of phytoplankton biomass by macrozooplankton in these shallow subtropical lakes. (c) 2007 Elsevier GmbH. All rights reserved

Histone deacetylase 6 modulates macrophage infiltration during inflammation

Mice with histone deacetylase 6 (HDAC6) deficiency grow and develop normally but exhibit impaired immune response. The molecular mechanisms for this phenotype remain largely elusive. Methods: A mouse acute peritonitis model was used to study the infiltration of neutrophils and monocyte-derived macrophages. In vitro cell motility assays were performed to analyze monocyte/macrophage recruitment. Fluorescence microscopy and flow cytometry were performed to examine the phagocytic ability of macrophages. Immunofluorescence microscopy was used to investigate protein localization, protrusion formation, and microtubule acetylation. Results: HDAC6 deficiency does not affect neutrophil infiltration, but instead attenuates the infiltration of monocyte-derived macrophages into the peritoneal cavity. HDAC6 plays a specific role in monocyte/macrophage recruitment. Loss of HDAC6 suppresses the phagocytic capacity of macrophages challenged with E. coli. Lipopolysaccharide stimulation results in the translocation of HDAC6 and cortactin from the cytosol to the cell periphery, promotes the formation of filopodial protrusions, and enhances microtubule acetylation around the microtubule-organizing center, all of which are abrogated by HDAC6 deficiency. Conclusion: These findings implicate HDAC6 in the innate immune response and suggest that it may serve as a promising target for the treatment of macrophage-associated immune diseases

HDAC6 deacetylates IDH1 to promote the homeostasis of hematopoietic stem and progenitor cells.

Hematopoietic stem and progenitor cells (HSPCs) are cells mainly present in the bone marrow and capable of forming mature blood cells. However, the epigenetic mechanisms governing the homeostasis of HSPCs remain elusive. Here, we demonstrate an important role for histone deacetylase 6 (HDAC6) in regulating this process. Our data show that the percentage of HSPCs in Hdac6 knockout mice is lower than in wild-type mice due to decreased HSPC proliferation. HDAC6 interacts with isocitrate dehydrogenase 1 (IDH1) and deacetylates IDH1 at lysine 233. The deacetylation of IDH1 inhibits its catalytic activity and thereby decreases the 5-hydroxymethylcytosine level of ten-eleven translocation 2 (TET2) target genes, changing gene expression patterns to promote the proliferation of HSPCs. These findings uncover a role for HDAC6 and IDH1 in regulating the homeostasis of HSPCs and may have implications for the treatment of hematological diseases