2,113 research outputs found
Mott transition in the -flux SU() Hubbard model on a square lattice
We employ the projector quantum Monte Carlo simulations to study the
ground-state properties of the square-lattice SU(4) Hubbard model with a
flux per plaquette. In the weak coupling regime, its ground state is in the
gapless Dirac semi-metal phase. With increasing repulsive interaction, we show
that, a Mott transition occurs from the semimetal to the valence bond solid,
accompanied by the discrete symmetry breaking. Our simulations
demonstrate the existence of a second-order phase transition, which confirms
the Ginzburg-Landau analysis. The phase transition point and the critical
exponent are also estimated. To account for the effect of a flux
on the ordering in the strong coupling regime, we analytically derive by the
perturbation theory the ring-exchange term which describes the leading-order
difference between the -flux and zero-flux SU(4) Hubbard models.Comment: 8 pages, 9 figure
Precipitating Ordered Skyrmion Lattices from Helical Spaghetti
Magnetic skyrmions have been the focus of intense research due to their
potential applications in ultra-high density data and logic technologies, as
well as for the unique physics arising from their antisymmetric exchange term
and topological protections. In this work we prepare a chiral jammed state in
chemically disordered (Fe, Co)Si consisting of a combination of
randomly-oriented magnetic helices, labyrinth domains, rotationally disordered
skyrmion lattices and/or isolated skyrmions. Using small angle neutron
scattering, (SANS) we demonstrate a symmetry-breaking magnetic field sequence
which disentangles the jammed state, resulting in an ordered, oriented skyrmion
lattice. The same field sequence was performed on a sample of powdered Cu2OSeO3
and again yields an ordered, oriented skyrmion lattice, despite relatively
non-interacting nature of the grains. Micromagnetic simulations confirm the
promotion of a preferred skyrmion lattice orientation after field treatment,
independent of the initial configuration, suggesting this effect may be
universally applicable. Energetics extracted from the simulations suggest that
approaching a magnetic hard axis causes the moments to diverge away from the
magnetic field, increasing the Dzyaloshinskii-Moriya energy, followed
subsequently by a lattice re-orientation. The ability to facilitate an emergent
ordered magnetic lattice with long-range orientation in a variety of materials
despite overwhelming internal disorder enables the study of skyrmions even in
imperfect powdered or polycrystalline systems and greatly improves the ability
to rapidly screen candidate skyrmion materials
Breath detection algorithms affect multiple-breath washout outcomes in pre-school and school age children.
BACKGROUND
Accurate breath detection is essential for the computation of outcomes in the multiple-breath washout (MBW) technique. This is particularly important in young children, where irregular breathing is common, and the designation of inspirations and expirations can be challenging.
AIM
To investigate differences between a commercial and a novel breath-detection algorithm and to characterize effects on MBW outcomes in children.
METHODS
We replicated the signal processing and algorithms used in Spiroware software (v3.3.1, Eco Medics AG). We developed a novel breath detection algorithm (custom) and compared it to Spiroware using 2,455 nitrogen (N2) and 325 sulfur hexafluoride (SF6) trials collected in infants, children, and adolescents.
RESULTS
In 83% of N2 and 32% of SF6 trials, the Spiroware breath detection algorithm rejected breaths and did not use them for the calculation of MBW outcomes. Our custom breath detection algorithm determines inspirations and expirations based on flow reversal and corresponding CO2 elevations, and uses all breaths for data analysis. In trials with regular tidal breathing, there were no differences in outcomes between algorithms. However, in 10% of pre-school children tests the number of breaths detected differed by more than 10% and the commercial algorithm underestimated the lung clearance index by up to 21%.
CONCLUSION
Accurate breath detection is challenging in young children. As the MBW technique relies on the cumulative analysis of all washout breaths, the rejection of breaths should be limited. We provide an improved algorithm that accurately detects breaths based on both flow reversal and CO2 concentration
Reconstitution of Targeted Deadenylation by the Ccr4-Not Complex and the YTH Domain Protein Mmi1
SummaryCcr4-Not is a conserved protein complex that shortens the 3âČ poly(A) tails of eukaryotic mRNAs to regulate transcript stability and translation into proteins. RNA-binding proteins are thought to facilitate recruitment of Ccr4-Not to certain mRNAs, but lack of an in-vitro-reconstituted system has slowed progress in understanding the mechanistic details of this specificity. Here, we generate a fully recombinant Ccr4-Not complex that removes poly(A) tails from RNA substrates. The intact complex is more active than the exonucleases alone and has an intrinsic preference for certain RNAs. The RNA-binding protein Mmi1 is highly abundant in preparations of native Ccr4-Not. We demonstrate a high-affinity interaction between recombinant Ccr4-Not and Mmi1. Using in vitro assays, we show that Mmi1 accelerates deadenylation of target RNAs. Together, our results support a model whereby both RNA-binding proteins and the sequence context of mRNAs influence deadenylation rate to regulate gene expression
The ÎŽâopioid receptor positive allosteric modulator BMS 986187 is a Gâproteinâbiased allosteric agonist
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149355/1/bph14602.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149355/2/bph14602_am.pd
Comparison of functional residual capacity between updated infant SF6 multiple-breath washout setups.
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Tutorial on model selection and validation of model input into precision dosing software for model-informed precision dosing
There has been rising interest in using model-informed precision dosing to provide personalized medicine to patients at the bedside. This methodology utilizes population pharmacokinetic models, measured drug concentrations from individual patients, pharmacodynamic biomarkers, and Bayesian estimation to estimate pharmacokinetic parameters and predict concentration-time profiles in individual patients. Using these individualized parameter estimates and simulated drug exposure, dosing recommendations can be generated to maximize target attainment to improve beneficial effect and minimize toxicity. However, the accuracy of the output from this evaluation is highly dependent on the population pharmacokinetic model selected. This tutorial provides a comprehensive approach to evaluating, selecting, and validating a model for input and implementation into a model-informed precision dosing program. A step-by-step outline to validate successful implementation into a precision dosing tool is described using the clinical software platforms Edsim++ and MwPharm++ as examples.</p
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