Imprints of neutrino-pair flavor conversions on nucleosynthesis in ejecta from neutron-star merger remnants

The remnant of neutron star mergers is dense in neutrinos. By employing inputs from one hydrodynamical simulation of a binary neutron star merger remnant with a black hole of $3\ M_\odot$ in the center, dimensionless spin parameter $0.8$ and an accretion torus of $0.3\ M_\odot$, the neutrino emission properties are investigated as the merger remnant evolves. Initially, the local number density of $\bar{\nu}_e$ is larger than that of $\nu_e$ everywhere above the remnant. Then, as the torus approaches self-regulated equilibrium, the local abundance of neutrinos overcomes that of antineutrinos in a funnel around the polar region. The region where the fast pairwise flavor conversions can occur shrinks accordingly as time evolves. Still, we find that fast flavor conversions do affect most of the neutrino-driven ejecta. Assuming that fast flavor conversions lead to flavor equilibration, a significant enhancement of nuclei with mass numbers $A>130$ is found as well as a change of the lanthanide mass fraction by more than a factor of a thousand. Our findings hint towards a potentially relevant role of neutrino flavor oscillations for the prediction of the kilonova (macronova) lightcurves and motivate further work in this direction.Comment: 16 pages, 12 figures, minor modifications to match the published versio

Resonant Production of Light Sterile Neutrinos in Compact Binary Merger Remnants

The existence of eV-mass sterile neutrinos is not ruled out because of persistent experimental anomalies. Upcoming multi-messenger detections of neutron-star merger remnants could provide indirect constraints on the existence of these particles. We explore the active-sterile flavor conversion phenomenology in a two-flavor scenario (1 active + 1 sterile species) as a function of the sterile neutrino mixing parameters, neutrino emission angle from the accretion torus, and temporal evolution of the merger remnant. The torus geometry and the neutron richness of the remnant are responsible for the occurrence of multiple resonant active-sterile conversions. The number of resonances strongly depends on the neutrino emission direction above or inside the remnant torus and leads to large production of sterile neutrinos (and no antineutrinos) in the proximity of the polar axis as well as more sterile antineutrinos than neutrinos in the equatorial region. As the black hole torus evolves in time, the shallower baryon density is responsible for more adiabatic flavor conversion, leading to larger regions of the mass-mixing parameter space being affected by flavor mixing. Our findings imply that the production of sterile states can have indirect implications on the disk cooling rate, its outflows, and related electromagnetic observables which remain to be assessed.Comment: 16 pages, including 12 figure

End of life content in geriatric textbooks: what is the current situation?

BACKGROUND: Physicians caring for elderly people encounter death and dying more frequently than their colleagues in most other disciplines. Therefore we sought to examine the end-of-life content in popular geriatric textbooks and determine their usefulness in helping geriatricians manage patients at the end of their lives. METHODS: Five popular geriatric textbooks were chosen. Chapters on Alzheimer's disease, stroke, chronic heart failure, chronic obstructive pulmonary disease and lung cancer were examined because of their high mortality rates among the elderly patients. Text relevant to end-of-life care was highlighted. Two reviewers independently coded text into 10 pre specified domains and rated them for the presence of end-of-life information. Content was rated as absent, minimally helpful, or helpful. The proportion of helpful information was calculated. RESULTS: The textbook with the best end-of-life coverage contained 38% helpful information, the worst had only 15% helpful information. Minimally helpful information ranged from 24% to 50%. As much as 61% of the content in one textbook contained no helpful information at all. Of the ten domains, epidemiology, disease progression and prognostic factors were fairly well covered. Information on advance care planning, ethical issues, decision making and effects of death and dying on patient's family were generally lacking under the individual diseases though they were covered as general topics in other parts of the textbooks. All except one textbook dedicated a chapter to the care of the dying. CONCLUSION: This study showed that end-of-life content in geriatric textbooks differed significantly. Most of the textbooks lack good coverage on end-of-life care and more can be done to improve on this

Mechanism of glycan receptor recognition and specificity switch for avian, swine, and human adapted influenza virus hemagglutinins: a molecular dynamics perspective.

Hemagglutinins (HA's) from duck, swine, and human influenza viruses have previously been shown to prefer avian and human glycan receptor analogues with distinct topological profiles, pentasaccharides LSTa (alpha-2,3 linkage) and LSTc (alpha-2,6 linkage), in comparative molecular dynamics studies. On the basis of detailed analyses of the dynamic motions of the receptor binding domains (RBDs) and interaction energy profiles with individual glycan residues, we have identified approximately 30 residue positions in the RBD that present distinct profiles with the receptor analogues. Glycan binding constrained the conformational space sampling by the HA. Electrostatic steering appeared to play a key role in glycan binding specificity. The complex dynamic behaviors of the major SSE and trimeric interfaces with or without bound glycans suggested that networks of interactions might account for species specificity in these low affinity and high avidity (multivalent) interactions between different HA and glycans. Contact frequency, energetic decomposition, and H-bond analyses revealed species-specific differences in HA-glycan interaction profiles, not readily discernible from crystal structures alone. Interaction energy profiles indicated that mutation events at the set of residues such as 145, 156, 158, and 222 would favor human or avian receptor analogues, often through interactions with distal asialo-residues. These results correlate well with existing experimental evidence, and suggest new opportunities for simulation-based vaccine and drug development

Deep learning can be used to classify and segment plant cell types in xylem tissue

Studies of plant anatomical traits are essential for understanding plant physiological adaptations to stressful environments. For example, shrubs in the chaparral ecosystem of southern California have adapted various xylem anatomical traits that help them survive drought and freezing. Previous studies have shown that xylem conduits with a narrow diameter allows certain chaparral shrub species to survive temperatures as low as -12 C. Other studies have shown that increased cell wall thickness of fibers surrounding xylem vessels improves resistance to water stress-induced embolism formation. Historically, these studies on xylem anatomical traits have relied on hand measurements of cells in light micrographs, but this approach is time- and labor-intensive. Here we propose that deep learning-based models can be used to rapidly detect, classify, and measure plant cells with high precision and accuracy. Our goal was to develop models that can detect and classify plant cell types with greater than 95% accuracy. In this project, we constructed a deep convolutional neural network (DCNN) to segment and classify cell types in light micrographs. We created an encoder-decoder U-Net architecture, where we used convolutional layers to encode the features of the cross section, and transposed convolutional layers to upscale the features to a vessel segmentation mask. We interleaved batch normalization and max pooling layers inside the encoder-decoder blocks to provide a strong regularization to the U-Net. For classification, we explored various transformers and convolutional neural networks to achieve a cell type classification accuracy of 98.1%. The testing samples were isolated from the training data, and our DCNN performed vessel segmentation on this dataset with high pixel classification accuracy (97.05%) and excellent precision score (80.71%) that represents the model’s ability to predict positive vessel-class pixel values. With further development, the DCNN may provide the ability to measure vessel thickness and area, while also potentially measuring vessel cell wall thickness by performing a digital subtraction of a cell wall mask and vessel mask. This approach could provide opportunities to rapidly analyze larger plant anatomy datasets, allowing us to scale up questions relating plant xylem structure and function to the level of ecosystems or the globe

Extracellular RNA in a single droplet of human serum reflects physiologic and disease states.

Extracellular RNAs (exRNAs) are present in human serum. It remains unclear to what extent these circulating exRNAs may reflect human physiologic and disease states. Here, we developed SILVER-seq (Small Input Liquid Volume Extracellular RNA Sequencing) to efficiently sequence both integral and fragmented exRNAs from a small droplet (5 μL to 7 μL) of liquid biopsy. We calibrated SILVER-seq in reference to other RNA sequencing methods based on milliliters of input serum and quantified droplet-to-droplet and donor-to-donor variations. We carried out SILVER-seq on more than 150 serum droplets from male and female donors ranging from 18 y to 48 y of age. SILVER-seq detected exRNAs from more than a quarter of the human genes, including small RNAs and fragments of mRNAs and long noncoding RNAs (lncRNAs). The detected exRNAs included those derived from genes with tissue (e.g., brain)-specific expression. The exRNA expression levels separated the male and female samples and were correlated with chronological age. Noncancer and breast cancer donors exhibited pronounced differences, whereas donors with or without cancer recurrence exhibited moderate differences in exRNA expression patterns. Even without using differentially expressed exRNAs as features, nearly all cancer and noncancer samples and a large portion of the recurrence and nonrecurrence samples could be correctly classified by exRNA expression values. These data suggest the potential of using exRNAs in a single droplet of serum for liquid biopsy-based diagnostics

Fast neutrino flavor conversion, ejecta properties, and nucleosynthesis in newly-formed hypermassive remnants of neutron-star mergers

Neutrinos emitted in the coalescence of two neutron stars affect the dynamics of the outflow ejecta and the nucleosynthesis of heavy elements. In this work, we analyze the neutrino emission properties and the conditions leading to the growth of flavor instabilities in merger remnants consisting of a hypermassive neutron star and an accretion disk during the first 10 ms after the merger. The analyses are based on hydrodynamical simulations that include a modeling of neutrino emission and absorption effects via the "Improved Leakage-Equilibration-Absorption Scheme" (ILEAS). We also examine the nucleosynthesis of the heavy elements via the rapid neutron-capture process (r-process) inside the material ejected during this phase. The dominant emission of $\bar\nu_e$ over $\nu_e$ from the merger remnant leads to favorable conditions for the occurrence of fast pairwise flavor conversions of neutrinos, independent of the chosen equation of state or the mass ratio of the binary. The nucleosynthesis outcome is very robust, ranging from the first to the third r-process peaks. In particular, more than $10^{-5}$ $M_\odot$ of strontium are produced in these early ejecta that may account for the GW170817 kilonova observation. We find that the amount of ejecta containing free neutrons after the $r$-process freeze-out, which may power early-time UV emission, is reduced by roughly a factor of 10 when compared to simulations that do not include weak interactions. Finally, the potential flavor equipartition between all neutrino flavors is mainly found to affect the nucleosynthesis outcome in the polar ejecta within $\lesssim 30^\circ$, by changing the amount of the produced iron-peak and first-peak nuclei, but it does not alter the lanthanide mass fraction therein.Comment: matches the published versio