Bayesian Reconstruction of Local Universe Density and Velocity Fields Using 2MASS Data
Researchers used Bayesian methods to reconstruct the local density and velocity fields from the 2MASS Redshift Survey and validated their results against independent Cosmicflows-4 galaxy observations. The reconstruction employed a Zel'dovich-approximation forward model constrained by observational data and tested through multiple independent comparison methods. This work demonstrates that large-scale gravitational flows in the nearby Universe can be accurately mapped and provides validated initial conditions for cosmological simulations.
A new study presents a field-level Bayesian reconstruction of the local Universe's density and velocity structure using data from the 2MASS Redshift Survey (2MRS). The researchers employed a sophisticated forward-modeling approach based on the Zel'dovich approximation, incorporating realistic observational effects including the survey's selection function, redshift-space distortions, and galaxy bias. The reconstructed gravitational velocity field was independently validated against peculiar velocities from the Cosmicflows-4 catalog through multiple statistical tests, showing good agreement without requiring smoothing of the observed data. The team also evolved their constrained initial conditions using N-body simulations (Gadget-4), demonstrating that the reconstruction captures large-scale structure while developing realistic nonlinear features at smaller scales. These results validate the methodology for mapping gravitational flows in the local Universe and provide initial conditions suitable for constrained cosmological simulations.
What different sources said
- arXiv astro-phCenter
Bayesian Reconstruction of the Local Universe from 2MRS: Testing the Gravitational Flow with Cosmicflows-4
Related
Gut Bacteria Enzyme Found to Break Down Heat-Processed Food Compounds, Producing Novel Biogenic Amines
Researchers have discovered that an enzyme in common gut bacteria can degrade N-epsilon-carboxymethyllysine (CML), a compound formed during thermal food processing, producing previously unknown biogenic amines. The enzyme, ornithine decarboxylase SpeC from enterobacteria, acts on CML and related modified lysine derivatives through a low-level 'underground' catalytic activity. This finding suggests a previously unrecognized communication axis between thermally processed dietary compounds and gut microbial physiology, with potential implications for host health.
Full-Length Gene Sequencing Reveals Two Distinct Bacterial Communities in Black-Legged Ticks Expanding Into Canada
Researchers used Oxford Nanopore full-length 16S rRNA gene sequencing to characterize the microbiome of Ixodes scapularis black-legged ticks collected in Nova Scotia, Canada, distinguishing between tick-adapted bacteria and environmentally acquired bacteria. The study comes as I. scapularis — the primary vector of Lyme disease — is rapidly expanding northward into Canada due to climate change. The findings suggest that environmentally derived bacteria in tick microbiomes are not mere contamination, which has implications for how tick microbiome data is collected and interpreted across surveillance studies.
Study Identifies Metabolic Link Between Cell Envelope Stress and Biofilm Formation in Bacteria
Researchers have discovered that the metabolite acetyl-CoA directly inhibits enzymes that degrade the bacterial signaling molecule c-di-GMP, connecting cell envelope biosynthesis stress to biofilm formation in Pseudomonas aeruginosa. The study found that sub-inhibitory concentrations of antibiotics targeting early peptidoglycan biosynthesis — but not other antibiotic classes — elevate c-di-GMP levels by reducing phosphodiesterase activity, with acetyl-CoA competing for the enzyme active site. Because the relevant enzyme domain is broadly conserved across bacterial species, this checkpoint mechanism may be widespread and could have implications for understanding antibiotic-induced biofilm responses.