Browse Articles

Spin adaptation of the cumulant expansions of reduced density matrices

We develop a systematic framework for the spin adaptation of the cumulants of p-particle reduced density matrices (RDMs), with explicit constructions for p = 1 to 3. These spin-adapted cumulants enable rigorous treatment of both Ŝz and Ŝ2 symmetries in quantum systems, providing a foundation for spin-resolved electronic structure methods. We show that complete spin adaptation—referred to as completeS-representability—can be enforced by constraining the variances of Ŝz and Ŝ2, which require the 2-RDM and 4-RDM, respectively. Importantly, the cumulants of RDMs scale linearly with system size—size-extensive—making them a natural object for incorporating spin symmetries in scalable electronic structure theories. The developed formalism is applicable to density-based methods, one-particle RDM functional theories, and two-particle RDM methods. We further extend the approach to spin–orbit-coupled systems via total angular momentum adaptation. Beyond spin, the framework enables the adaptation of RDM theories to additional symmetries through the construction of suitable irreducible tensor operators.

Multi-level trend analysis of extreme climate indices by a novel hybrid method of fuzzy logic and innovative trend analysis

Microcavity-enhanced exciton dynamics in light-harvesting complexes: Insights from Redfield theory

We investigated the exciton transfer dynamics in photosynthetic light-harvesting complex 2 (LH2) coupled to an optical microcavity. Using computational simulations based on Redfield theory, we analyzed how microcavity coupling influences energy relaxation and transfer within and between LH2 aggregates. Our results show that the exciton transfer rate between B850 rings follows a square dependence on the light–matter coupling strength, in agreement with Fermi’s golden rule. Interestingly, the energy transfer rate remains almost independent of the number of LH2 complexes. This behavior is explained by the molecular components of the polaritonic wavefunction overlaps. These findings highlight the crucial role of cavity-induced polaritonic states in mediating energy transport and provide a theoretical framework for optimizing microcavity environments to enhance exciton mobility in light-harvesting systems and related photonic applications.

HAVIT: research on vision-language gesture interaction mechanism for smart furniture

Abstract With the rapid development of smart furniture, gesture recognition has gained increasing attention as a natural and intuitive interaction method. However, in practical applications, issues such as limited data resources and insufficient semantic understanding have significantly constrained the effectiveness of gesture recognition technology. To address these challenges, this study proposes HAVIT, a hybrid deep learning model based on Vision Transformer and ALBEF, aimed at enhancing the performance of gesture recognition systems under data-scarce conditions. The model achieves efficient feature extraction and accurate recognition of gesture characteristics through the organic integration of Vision Transformer’s feature extraction capabilities and ALBEF’s semantic understanding mechanism. Experimental results demonstrate that on a fully labeled dataset, the HAVIT model achieved a classification accuracy of 91.83% and an AUC value of 0.92; under 20% label deficiency conditions, the model maintained an accuracy of 86.89% and an AUC value of 0.88, exhibiting strong robustness. The research findings provide new solutions for the development of smart furniture interaction technology and hold significant implications for advancing practical applications in this field.

External field-induced caloric effects in liquid crystals from molecular simulation

In the search for alternative, environmentally friendly refrigeration technologies, caloric effects play an important role. Over the past years, liquid crystals have emerged as promising caloric materials. Here, we present a molecular simulation study of the electrocaloric and magnetocaloric effect in liquid crystals exhibiting a nematic–isotropic phase transition. The indirect approach for determining the caloric response is used in combination with molecular dynamics simulations based on the Gay–Berne model. The simulations confirm that the largest response is present at temperatures just above the phase transition and predict the magnitude of the electrocaloric response to be ∼1.6 kJ/kg for an applied electric field of 1600 kV/cm. A much weaker magnetocaloric response is predicted, ∼0.4 kJ/kg for an applied magnetic field of 200 T, indicating that electric fields are much more promising for use in applications than magnetic fields.

Enhanced pre-recruitment framework for clinical trial questionnaires through the integration of large language models and knowledge graphs

Basal dislocations in proton-ordered hexagonal ice

We use molecular dynamics modeling to investigate the core structures and critical resolved shear stresses for glide of basal dislocations in proton-ordered hexagonal ice. Straight and kinked dislocations of 60° and screw character residing on shuffle and glide set planes are investigated. Except for the 60° shuffle, all these dislocations are sessile: they do not move for modulus-normalized resolved shear stresses up to 0.11 or higher. Straight 60° shuffle dislocations move at different critical resolved shear stresses, depending on the orientation of the core relative to molecules in the crystal as well as on the sense of loading. The lowest modulus-normalized stress to move a straight 60° shuffle dislocation is 0.044: comparable to the Peierls barrier of diamond. Depending on their structure, kinks can either pin the dislocation or lower its critical resolved shear stress to a modulus-normalized level of 0.037. Our work shows that proton ordering does not ease dislocation glide in hexagonal ice. We discuss the consequences of these findings for theories of plastic flow in ice Ih and ice XI.

Chemosensory role of intracellular TAS2Rs, the activation of which triggers drug excretion by ABCB1 in cancer cells

Engineering living worms and active crystals with colloids propelled by attractive time-delayed feedback

Using computer simulations, we study the dynamics of colloidal particles with time-delayed feedback interactions. In particular, here, we consider “feedback-pullers,” i.e., colloidal particles that are pulled away from their current position toward an attractive ring centered around their past position. For a single particle, small rings lead to reduced diffusive motion, while large rings render activity to the particle. For multiple particles, the particles not only feel their own attractive ring but are also attracted by the rings around all other particles. As expected, for ring sizes larger than the particle diameter, the feedback leads to crystallites whose lattice constant is set by the feedback ring radius. However, here, we demonstrate that for long delays (compared to the Brownian time), the colloidal particles start to oscillate around their lattice positions, with the crystallites ultimately collapsing to a close-packed lattice whose lattice constant corresponds to the particle diameter. This effect is caused by the time delay between the particle misplacement within the lattice and the corresponding change in the feedback force. Furthermore, we show that apart from the expected hexagonal crystallites, the time delay may result in the formation of uncommon new states in the case that the ring size is chosen slightly smaller than the particle diameter. Here, particles self-assemble into and move collaboratively as “living worms” or as active square-lattice crystallites.

Author Correction: Longitudinal fecal microbiota and volatile metabolomics preceding necrotizing enterocolitis in preterm infants: a case–control study

Probing plexciton dynamics with higher-order spectroscopy

Coupling molecular transition dipole moments to surface-plasmon polaritons (SPPs) results in the formation of new optical quasiparticles, i.e., plexcitons. Mixing the specific properties of matter excitations and light modes has proven to be an efficient strategy to alter a variety of molecular processes, ranging from chemical reactions to exciton transport. Here, we investigate energy transfer in a plexcitonic system of zinc phthalocyanine molecules aggregated in the crystalline α-phase and an SPP on a planar gold surface. By tuning the angle of incidence, we vary the degree of mixing between excitonic and SPP character of the excited state. We apply our recently developed higher-order pump–probe spectroscopy to separate the system’s fifth-order signal describing the dynamics of two-particle interactions. The time it takes for two quasiparticles to meet and annihilate is a measure of their movement and, thus, the transport of excitation energy in the system. We find that the transport extracted from the fifth-order signal is surprisingly unaffected by the mixing ratio of exciton and SPP contributions of the plexciton. Using a rate equation model, we explain this behavior by fast transition from the plexcitonic states to many localized excitonic dark states that do not have an SPP contribution. Our results give an indication of how hybrid exciton–plasmon systems should be designed to exploit the delocalization of the involved plasmon modes for improved transport.

Association between perceived financial hardship and sleep duration among Korean adolescents

Energy transduction in complex networks with multiple resources: The chemistry paradigm

We extend the traditional framework of steady state energy transduction—typically characterized by a single input and output—to multi-resource transduction in open chemical reaction networks (CRNs). Transduction occurs when stoichiometrically balanced processes are driven against their spontaneous directions by coupling them with thermodynamically favorable ones. However, when multiple processes (resources) interact through a shared CRN, identifying the relevant set of processes for analyzing transduction becomes a critical and complex challenge. To address this, we introduce a systematic procedure based on elementary processes, which cannot be further decomposed into subprocesses. Our theory generalizes the methodology used to define transduction efficiency in thermal engines operating between multiple heat baths. By selecting a reference equilibrium environment, it explicitly reveals the inherently relative nature of transduction efficiency and ties its definition to exergy. This framework also allows one to exclude unusable outputs from efficiency calculations. We further extend the concept of chemical gears to multi-process transduction, demonstrating their versatility as an analytical tool in complex settings. Finally, we apply our framework to central metabolic pathways, uncovering deep insights into their operation and highlighting the crucial difference between thermodynamic efficiencies and stoichiometric yields.

Development and validation of a visual nomogram for predicting clinically significant prostate cancer in negative mpMRI using 68Ga-PSMA PET/CT

Conductivity of concentrated salt solutions

The conductivity of concentrated salt solutions has posed a real puzzle for theories of electrolytes. Despite a quantitative understanding of dilute solutions, an analytical theory for concentrated ones has remained a challenge for almost a century, although a number of parameters and effects incorporated into theories increase with time. Here, we show that the conductivity of univalent salt solutions can be perfectly interpreted using a simple model that relies on a modified mean-field description of electrostatic interactions and on a classical approach to calculating colloid electrophoresis. We derive a compact equation, which predicts that the ratio of conductivity to that at an infinite dilution is the same for all salts and depends only on the product of the harmonic mean of ion hydrodynamic radii and the square root of concentration. Our equation fits very well the data for inorganic salts (up to a few mol/l), although at a very high dilution, the relaxation correction seems necessary.

Uncovering rain-fed resilience power of grass pea in Iran using AMMI, BLUP, and multi-trait stability parameters

Convolutional neural network approach to ion Coulomb crystal image analysis

This paper reports on the use of a convolutional neural network methodology to analyze fluorescence images of calcium-ion Coulomb crystals in the gas phase. A transfer-learning approach is adopted using the publicly available RESNET50 model. It is demonstrated that by retraining the neural network on around 500 000 simulated images, we are able to determine ion-numbers not only for a validation set of 100 000 simulated images but also for experimental calcium-ion images from two different laboratories using a wide range of ion-trap parameters. Absolute ion numbers in the crystal were determined for the experimental data with a percentage error of ∼10%. This analysis can be performed in a few seconds for an individual crystal image, and therefore, the method enables the objective, and efficient, analysis of such images in real time. The approach adopted also shows promising performance for identifying Ca+ ion numbers in images of mixed-species crystals, thereby enhancing the experimental methodologies for studying the kinetics and dynamics of cold ion–molecule reactions.

Systemic immune-inflammation index and postoperative sleep disturbance in elderly patients with total joint arthroplasty: A prospective cohort study

Ehrenfest dynamics accelerated with SPEED

Mixed quantum-classical methods, such as surface hopping and Ehrenfest dynamics, have proven useful for describing molecular processes involving multiple electronic states. These methods require propagating many independent trajectories, which is computationally demanding. Therefore, we propose the single potential evaluation Ehrenfest dynamics (SPEED), a variation of Ehrenfest dynamics where all trajectories are propagated using a common local quadratic effective potential in the diabatic representation. This approach replaces the computational cost of propagating multiple trajectories with the evaluation of a single Hessian at each time step. We demonstrate the equivalence of standard Ehrenfest dynamics and SPEED in two realistic systems with (at most) quadratic diabatic potential energy surfaces and vibronic couplings: a quadratic vibronic coupling Hamiltonian model describing internal conversion in pyrazine and a model of atomic adsorption on a solid surface. The efficiency gain of our approach is particularly advantageous in on-the-fly ab initio applications. For this reason, we combined SPEED with the ALMO(MSDFT2) electronic structure method, which provides the diabatic potential describing charge transfer between two molecules. We find that SPEED qualitatively captures the temperature dependence of the hole transfer rate between two furan moieties and accurately predicts the final charge distribution after the collision. In contrast, but as expected, our approach is insufficient for describing photoisomerization of retinal due to the high anharmonicity of the potential energy surfaces already in the diabatic representation.

Influence of vanadium oxide on the structural, optical, mechanical and dielectric properties of cadmium borate glasses

Abstract The melt-quenching method has been employed to fabricate 30B2O3–(70−x)CdO-xV2O5; x = 0, 1, 2, 3, and 5 mol% glasses. The physical, optical, mechanical, and dielectric properties of the prepared glasses were measured. Structural FTIR spectra and their related deconvolution process showed distinct absorption bands, from which some parameters especially, the N4 ratio, could be determined by calculating the area under peaks. The successive addition of V2O5 up to 2 mol% at the expense of CdO in the glass network led to an increase in density from 4.27 to 4.69 g/cm3 for the prepared glasses while adding more V2O5 led to a decrease in density. The molar volume showed the same trend that occurred in the density, but in an opposite direction, as it decreased by increasing V2O5 content till the 2 mol% samples, then increased. The optical energy gap values (Eg) were calculated and were found to decrease from 2.95 to 1.35 eV with increasing levels of V2O5. With varying V2O5 concentrations, the mechanical characteristics of cadmium borate glasses increased up to 2%, declined at 3%, and then improved once again at mol%. The maximum microhardness, fracture toughness, and Young’s modulus were 624.12 HV, 2.87 MPa.m0.5, and 63.71 GPa for samples contained 2 mol% V2O5 which improved about 14.91, 32.26, and 21.84% compared to unreinforced glass sample. In addition, adding V2O5 and increasing the frequency had a positive effect on the electrical conductivity with the real and imaginary dielectric constant, and tan δ is the opposite. The electrical conductivity and tan δ of glass containing high V2O5 at a frequency of 20 MHz were 1.45 × 10⁻2 S/cm and 0.0619, respectively, at a frequency of 20 mΩ.