Subsequent Relaxation Research Articles

Extracting dynamical maps of non-Markovian open quantum systems.

The most general description of quantum evolution up to a time τ is a completely positive tracing preserving map known as a dynamical mapΛ̂(τ). Here, we consider Λ̂(τ) arising from suddenly coupling a system to one or more thermal baths with a strength that is neither weak nor strong. Given no clear separation of characteristic system/bath time scales, Λ̂(τ) is generically expected to be non-Markovian; however, we do assume the ensuing dynamics has a unique steady state, implying the baths possess a finite memory time τm. By combining several techniques within a tensor network framework, we directly and accurately extract Λ̂(τ) for a small number of interacting fermionic modes coupled to infinite non-interacting Fermi baths. First, we use an orthogonal polynomial mapping and thermofield doubling to arrive at a purified chain representation of the baths whose length directly equates to a time over which the dynamics of the infinite baths is faithfully captured. Second, we employ the Choi-Jamiolkowski isomorphism so that Λ̂(τ) can be fully reconstructed from a single pure state calculation of the unitary dynamics of the system, bath and their replica auxiliary modes up to time τ. From Λ̂(τ), we also compute the time local propagator L̂(τ). By examining the convergence with τ of the instantaneous fixed points of these objects, we establish their respective memory times τmΛ and τmL. Beyond these times, the propagator L̂(τ) and dynamical map Λ̂(τ) accurately describe all the subsequent long-time relaxation dynamics up to stationarity. These timescales form a hierarchy τmL≤τmΛ≤τre, where τre is a characteristic relaxation time of the dynamics. Our numerical examples of interacting spinless Fermi chains and the single impurity Anderson model demonstrate regimes where τre ≫ τm, where our approach can offer a significant speedup in determining the stationary state compared to directly simulating the long-time limit. Our results also show that having access to Λ̂(τ) affords a number of insightful analyses of the open system thus far not commonly exploited.

Tectonostratigraphic models of an extensional back-arc basin: inferences for the evolution of the Pannonian Basin system

The subsidence history and sedimentary architecture of extensional basins are controlled by the interplay between tectonics, mantle dynamics, and climatic variations. Observations from outcrop to regional seismic scales coupled with numerical modelling techniques, including basin-scale stratigraphic, crustal-scale tectonic and mantle-scale subduction models contribute to quantify basin evolution. Here, we review and discuss both tectonic and stratigraphic applications of such models and compare them with observations from the Pannonian Basin system of Central Europe. We show that diachronous localization of back-arc extension, crustal thinning, asthenospheric upwelling and subsequent thermal relaxation are superimposed on an overall slow plate convergence. These processes result in contrasting subsidence and uplift patterns and a variable heat flow evolution in different parts of the basin system. The crustal stress-field of the subbasins does not always reflect their contrasting vertical motions. Extensional deformation generally migrates from the basin margins towards the basin centre. Structural inversion is localized along hot and weak inherited zones from the Middle Miocene to Present. Tectonic subsidence focuses sedimentation along deep depocenters, sourced by exhumed footwalls and from the neighbouring orogens. The overall post-rift sediment progradation are influenced by inherited bathymetries from the preceding syn-rift stage and by enhanced differential vertical motions.

Electron trapping in HfO2 layer deposited over a HF last treated silicon substrate

Electron trapping in HfO2-based MOS structures was studied through pulsed capacitance-voltage (C-V) technique. 10 nm HfO2 layer was deposited by atomic layer deposition over a HF last treated Si substrate. The C-V curves were observed to shift to positive voltages driven by the positive applied voltage along the pulses, consistent with electron trapping due to tunneling transitions between the substrate and pre-existing defects within the oxide and the subsequent lattice relaxation through electron-phonon interaction. The dependences of the voltage shift for a given capacitance value (ΔVC) with stress bias and time, allowed to distinguish two mechanisms. An initial trapping process occurs for times shorter than the microsecond, probably associated with a thin non-stoichiometric SiOx interfacial layer, which is followed by a trapping process that starts after tens of μs and progressively slowed down, associated with traps within the HfO2 layer. Numerical simulations yield for the HfO2 traps an energy of 1.3 eV below the conduction band edge, decreasing exponentially with the distance from the Si interface with a characteristic length of 1.7 nm; and phonon and relaxation energies of 50 meV and 1 eV, respectively. These physical parameters are consistent with previous reports of electron trapping in HfO2 layers deposited on a controlled interfacial layer, suggesting that trapping properties of defects inside the HfO2 layer are insensitive to the treatment of the Si surface before HfO2 deposition. On the other hand, the observed large initial trapping suggests that the non-controlled SiOx interfacial region is more defective than a controlled one.

Theoretical Description of Pump-Probe Experiments in Charge-Density-Wave Materials out to Long Times

We describe coupled nonequilibrium electron-phonon systems semiclassically—Ehrenfest dynamics for the phonons and quantum mechanics for the electrons—using a classical Monte Carlo approach that determines the nonequilibrium response to a large pump field. The semiclassical approach is expected to be accurate, because the phonons are excited to average energies much higher than the phonon frequency, eliminating the need for a quantum description. The numerical efficiency of this method allows us to perform a self-consistent time evolution out to very long times (tens of picoseconds), enabling us to model pump-probe experiments of a charge-density-wave (CDW) material. Our system is a half-filled, one-dimensional (1D) Holstein chain that exhibits CDW ordering due to a Peierls transition. The chain is subjected to a time-dependent electromagnetic pump field that excites it out of equilibrium, and then a second probe pulse is applied after a time delay. By evolving the system to long times, we capture the complete process of lattice excitation and subsequent relaxation to a new equilibrium, due to an exchange of energy between the electrons and the lattice, leading to lattice relaxation at finite temperatures. We employ an indirect (impulsive) driving mechanism of the lattice by the pump pulse due to the direct driving of the electrons. We identify two driving regimes, where the pump can either cause small perturbations or completely invert the initial CDW order. Our work successfully describes the ringing of the amplitude mode in CDW systems that has long been seen in experiment but never successfully explained by microscopic theory. We also describe the fluence-dependent crossover that inverts the CDW order parameter and changes the phonon dynamics. Finally, we illustrate how this method can examine a number of different types of experiments including photoemission, x-ray diffraction, and two-dimensional (2D) spectroscopy. Published by the American Physical Society 2024

Signaling Paradigms of H2S-Induced Vasodilation: A Comprehensive Review.

Hydrogen sulfide (H2S), a gas traditionally considered toxic, is now recognized as a vital endogenous signaling molecule with a complex physiology. This comprehensive study encompasses a systematic literature review that explores the intricate mechanisms underlying H2S-induced vasodilation. The vasodilatory effects of H2S are primarily mediated by activating ATP-sensitive potassium (K_ATP) channels, leading to membrane hyperpolarization and subsequent relaxation of vascular smooth muscle cells (VSMCs). Additionally, H2S inhibits L-type calcium channels, reducing calcium influx and diminishing VSMC contraction. Beyond ion channel modulation, H2S profoundly impacts cyclic nucleotide signaling pathways. It stimulates soluble guanylyl cyclase (sGC), increasing the production of cyclic guanosine monophosphate (cGMP). Elevated cGMP levels activate protein kinase G (PKG), which phosphorylates downstream targets like vasodilator-stimulated phosphoprotein (VASP) and promotes smooth muscle relaxation. The synergy between H2S and nitric oxide (NO) signaling further amplifies vasodilation. H2S enhances NO bioavailability by inhibiting its degradation and stimulating endothelial nitric oxide synthase (eNOS) activity, increasing cGMP levels and potent vasodilatory responses. Protein sulfhydration, a post-translational modification, plays a crucial role in cell signaling. H2S S-sulfurates oxidized cysteine residues, while polysulfides (H2Sn) are responsible for S-sulfurating reduced cysteine residues. Sulfhydration of key proteins like K_ATP channels and sGC enhances their activity, contributing to the overall vasodilatory effect. Furthermore, H2S interaction with endothelium-derived hyperpolarizing factor (EDHF) pathways adds another layer to its vasodilatory mechanism. By enhancing EDHF activity, H2S facilitates the hyperpolarization and relaxation of VSMCs through gap junctions between endothelial cells and VSMCs. Recent findings suggest that H2S can also modulate transient receptor potential (TRP) channels, particularly TRPV4 channels, in endothelial cells. Activating these channels by H2S promotes calcium entry, stimulating the production of vasodilatory agents like NO and prostacyclin, thereby regulating vascular tone. The comprehensive understanding of H2S-induced vasodilation mechanisms highlights its therapeutic potential. The multifaceted approach of H2S in modulating vascular tone presents a promising strategy for developing novel treatments for hypertension, ischemic conditions, and other vascular disorders. The interaction of H2S with ion channels, cyclic nucleotide signaling, NO pathways, ROS (Reactive Oxygen Species) scavenging, protein sulfhydration, and EDHF underscores its complexity and therapeutic relevance. In conclusion, the intricate signaling paradigms of H2S-induced vasodilation offer valuable insights into its physiological role and therapeutic potential, promising innovative approaches for managing various vascular diseases through the modulation of vascular tone.

Electrochemical-mechanical coupled lithium growth in fiber-structured electrodes

Lithium plating (stripping) on the electrode surface and embedding inside the electrode occur simultaneously in lithium-ion batteries during fast (dis)charging, which involves both deposition and diffusion mechanisms. The paper presents a developed finite-element procedure that accommodates these two mechanisms, facilitating the modeling of the (dis)charging process in electrodes. The framework, which integrates interface electrochemical reaction kinetics, electrochemical-mechanical coupling, comprehensive constitutive models for silicon/graphite/lithium, and a surface growth re-meshing algorithm, is capable of real-time simulation of the surface deposition and coupled diffusion-deformation processes on the electrode substrate. We examined the effects of charging rate, diffusion rate and volumetric expansion on the stress of the plated lithium layer in a fiber-structured electrode. By accounting for creep in lithium metal and subsequent stress relaxation, we obtained time-dependent stress profiles in the plated lithium layer. As an application, we quantified electroplating stresses in both fiber-structured graphite and silicon electrodes. Taking the silicon electrode as a model case, we demonstrate that hollow fiber structural electrodes can also alleviate the stress in the surface lithium-plating layer. The numerical framework may be further applied to explorations for the optimization of electrode structures in advanced high performance lithium-ion batteries.

Resurgence of Kawasaki Disease Following Relaxation of Coronavirus Disease 2019 Pandemic Restrictions in Japan

ObjectivesTo compare the number and incidence of Kawasaki disease (KD) patients in years 2 through 4 of the coronavirus disease 2019 (COVID-19) pandemic, and determine the impact of 3 years of implementation infection control measures and their subsequent relaxation on the epidemiology of KD in Japan. Study designWe conducted a population-based, cohort study including consecutive KD patients in Kobe City between 2021 and 2023. We compared the incidence of KD cases, in relation to timing of infection control measures, as well as infectious disease cases based on a regional surveillance system. Data from a previous 2016 through 2020 study were used for comparison. ResultsA total of 566 children with KD were identified during the study period. During the infection control period in 2021 to 2022, the incidence of KD remained low compared with the pre-pandemic level (281.3 and 327.5/100,000 children aged 0-4 years in 2021to 2022 and 2016 through 2019, respectively), but a recovery trend began in the 0-1-year age group. During the relaxation period in 2023, the incidence of KD increased across a wide age range, reaching the highest recorded in Japan (426.7/100,000 children aged 0-4 years), and the median age of onset increased to age 30 months. The resurgence of KD coincided with the patterns for multiple infectious diseases in 2023. The seasonality of KD observed before the pandemic was altered. ConclusionsKD resurged in 2023 after relaxation of the prolonged COVID-19 pandemic restrictions in Japan. This phenomenon coincided with the rise of multiple infectious diseases, and supports the pathogenesis of KD being triggered by infectious agents.

Quantifying surface tension and viscosity in biomolecular condensates by FRAP-ID

Many proteins with intrinsically disordered regions undergo liquid-liquid phase separation under specific conditions in vitro and in vivo. These complex biopolymers form a metastable phase with distinct mechanical properties defining the timescale of their biological functions. However, determining these properties is nontrivial, even in vitro, and often requires multiple techniques. Here we report the measurement of both viscosity and surface tension of biomolecular condensates via correlative fluorescence microscopy and atomic force microscopy (AFM) in a single experiment (fluorescence recovery after probe-induced dewetting, FRAP-ID). Upon surface tension evaluation via regular AFM-force spectroscopy, controlled AFM indentations induce dry spots in fluorescent condensates on a glass coverslip. The subsequent rewetting exhibits a contact line velocity that is used to quantify the condensed-phase viscosity. Therefore, in contrast with fluorescence recovery after photobleaching (FRAP), where molecular diffusion is observed, in FRAP-ID fluorescence recovery is obtained through fluid rewetting and the subsequent morphological relaxation. We show that the latter can be used to cross-validate viscosity values determined during the rewetting regime. Making use of fluid mechanics, FRAP-ID is a valuable tool to evaluate the mechanical properties that govern the dynamics of biomolecular condensates and determine how these properties impact the temporal aspects of condensate functionality.

Charge Trapping and Emission during Bias Temperature Stressing of Schottky Gate GaN-on-Silicon HEMT Structures Targeting RF/mm Wave Power Amplifiers.

For operation as power amplifiers in RF applications, high electron mobility transistor (HEMT) structures are subjected to a range of bias conditions, applied at both the gate and drain terminals, as the device is biased from the OFF- to ON-state conditions. The stability of the device threshold voltage (Vt) condition is imperative from a circuit-design perspective and is the focus of this study, where stresses in both the ON and OFF states are explored. We see rapid positive threshold voltage increases under negative bias stress and subsequent recovery (i.e., Vt reduces), whereas conversely, we see a negative Vt shift under positive stress and Vt increase during the subsequent relaxation phase. These effects are correlated with the thickness of the GaN layer and ultimately result from the deep carbon-acceptor levels in the C-GaN back barrier incorporated to screen the buffer between the silicon substrate and the epitaxially grown GaN layer. Methods to mitigate this effect are explored, and the consequences are discussed.

Momentum-Space Observation of Optically Excited Nonthermal Electrons in Graphene with Persistent Pseudospin Polarization.

The unique optical properties of graphene, with broadband absorption and ultrafast response, make it a critical component of optoelectronic and spintronic devices. Using time-resolved momentum microscopy with high data rate and high dynamic range, we report momentum-space measurements of electrons promoted to the graphene conduction band with visible light and their subsequent relaxation. We observe a pronounced nonthermal distribution of nascent photoexcited electrons with lattice pseudospin polarization in remarkable agreement with results of simple tight-binding theory. By varying the excitation fluence, we vary the relative importance of electron-electron vs electron-phonon scattering in the relaxation of the initial distribution. Increasing the excitation fluence results in increased noncollinear electron-electron scattering and reduced pseudospin polarization, although up-scattered electrons retain a degree of polarization. These detailed momentum-resolved electron dynamics in graphene demonstrate the capabilities of high-performance time-resolved momentum microscopy in the study of 2D materials and can inform the design of graphene devices.

Influence of the external magnetic field on structural characteristics of granular Co-Cu thin film alloys

We present the results of experimental studies of the influence of an external magnetic field on the structural characteristics (surface roughness and structural entropy) of nanogranular thin-film system based on Co and Cu. The samples CoxCu100-x in a wide range of compositions (17 at. % ≤ x ≤ 69 at. %) with the thickness of d = 35 nm were obtained by electron-beam co-evaporation using two independent electron guns. After obtaining, the films were annealed in a vacuum at a temperature of 800 K for 30 min. The studies of magnetoresistive properties have shown that the maximum giant magnetoresistance (GMR) amplitude (1.7 % in the transverse and 1.6 % in the longitudinal measurement geometries) in a magnetic field of H = 4.5 kOe at room temperature was observed in the Co21Cu79 film alloy. Transmission electron microscopy showed that this sample contains hcp-Co granules with a size of L = 5 ÷ 12 nm in a matrix of metastable fcc-Cu(Co) solid solution. The influence of the external magnetic field on the structural characteristics and surface morphology of the Co21Cu79 thin-film alloy was investigated using atomic force microscopy (AFM). It was found that a first impact of application of external magnetic field with H = 0.5 kOe causes a decrease in the values of the arithmetic mean Ra, and quadratic mean Rq, of the film roughness and structural entropy S. A decreases in Ra by 8.5 %, Rq by 6.5 %, and structural entropy S by 6.5 % were observed. After application of a larger magnetic field with H = 1.0 kOe and during the subsequent relaxation of the structure within 15 h after the field is turned off, the values of the structural parameters of the film surface did not change significantly.

Thermal evolution of the North China Craton revealed by microsampling garnet geochronology on single xenoliths

Granulite xenoliths, sourced from the lower cratonic crust and brought to the Earth's surface within volcanic rocks, offer unique insights into the formation and destruction of cratons. Age determinations are essential for constructing the thermal history of cratons. However, accurate dating is complicated by the xenoliths' extended exposure to high temperatures and their complex thermal histories. Specifically, the effects of extended lower crust residency and entrainment heating on coupled Sm–Nd and Lu–Hf systematics remain to be explored. Six xenoliths hosted in the Mesozoic dioritic porphyry from the eastern North China Craton were sampled from center to edge using micro-drilling/sawing techniques. From each xenolith, two to four concentric zones were successfully extracted for coupled Lu–Hf and Sm–Nd geochronological analysis. These xenoliths predominantly exhibit a granoblastic texture, with minerals that are mostly unzoned. Textural and chemical analyses of minerals indicate a decompression process following the granulite-facies metamorphism, with subsequent multiple reheating events. Thermobarometric calculations suggest granulite-facies equilibration at temperatures of ∼750 °C and pressures of 1.2–2.0 GPa. Consistent Lu–Hf and U–Pb ages of ca. 1.7 Ga, obtained from garnet, zircon, and titanite in chemical and textural equilibrium, are attributed to granulite-facies metamorphism. The Paleoproterozoic Lu–Hf ages and the Neoproterozoic Sm–Nd dates are indistinguishable across all concentric zones within each xenolith, whereas Sm–Nd ages are consistently ∼1.0 Ga younger than the corresponding Lu–Hf ages. This discrepancy suggests a complex history for this section of the lower cratonic crust, marked by a granulite-facies metamorphic event around 1.7 Ga, followed by prolonged cooling. A significant heating event during the Tonian, likely due to regional mantle plume activity, is inferred to have partially or completely reset the Sm–Nd isochrons. This thermal event and subsequent thermal relaxation on the samples at different residence depths thereby decoupled the Sm–Nd system from the Lu–Hf system, signifying a thermal pulse at the southern margin of North China Craton. The Mesozoic entrainment heating event appears to have had minimal impact on the Lu–Hf/Sm–Nd systematics of garnet and U–Pb of zircon/titanite. Our data highlight the potential of coupled microsampling Lu–Hf and Sm–Nd geochronology on individual xenoliths to reveal tectonic episodes within the lower crust that might be undetected by accessory mineral U–Pb geochronology.

Water absorption and property evolution of epoxy resin under hygrothermal environment

Changes in structure and properties of resin matrix caused by water absorption is one of the key factors affecting the long-term durability of fiber reinforced polymer composites used in civil engineering. In the present study, the water diffusion and structural change in an epoxy resin were investigated experimentally through immersion in deionized water at 40, 60 and 80 °C for 135 days. Water absorption, thermal, mechanical and microstructure analysis tests were conducted to evaluate the long-term property evolution. It was found that the water absorption of epoxy resin followed a two-stage model, including an initial Fick's diffusion response and a subsequent relaxation response. Long-term hygrothermal exposure brought about the structural change of epoxy resin, which led to the significant degradation up to 8%–30% in the mechanical properties and 21% in glass transition temperature, respectively. The resin plasticization and hydrolysis was the key factors for the degradation of thermal and mechanical properties. It was proved that the plasticization effect was reversible with the remove of bonding water after the drying. Based on the Arrhenius equation, the long-term life of flexural strength in two service environments were predicted to provide the application guideline. The significant degradation of flexural strength was occurred at the initial exposure of 2000 days and then reached to the stable strength retention of 69.6%.

Ultrafast excited state intramolecular proton transfer and isomerization of long-chain linked Schiff bases.

The ultrafast proton transfer and the following dynamics for aromatic Schiff bases N,N'-bis(salicylidene)ethylenediamine (salen) and N,N'-bis(salicylidene)-1,4-butylenediamine (salbn) were investigated with experimental and theoretical methods. A dual emission property with a large Stokes shift in salen and salbn indicates that excited state intramolecular proton transfer occurs with photoexcitation. An efficient single proton transfer was confirmed within 200fs for both molecules. Subsequently, a fast twisted motion of the keto moiety carries cis-keto to a relaxed stable geometry in the S1 state. Following the twisted motion, the phenol ring at keto moiety further rotates to a conical intersection with the ground state and a cis-trans isomerization occurs. The isomerization rate is high, which dominates the competition with the radiative transition, resulting in weak emission intensity. It is confirmed that the length of alkyl chain affects the direction of phenol ring twisting and rotation during the whole subsequent relaxation of excited cis-keto tautomer. Compared with polar solvent acetonitrile, the barrier of isomerization is higher and the hydrogen bond on keto moiety is stronger in nonpolar solvent toluene. It makes fluorescence radiation channels competing with isomerism more likely to occur, contributing to the observed difference of enol/keto emission ratios of salen and salbn in toluene and acetonitrile.

Obtaining Plasma–Dust Clouds from Meteoritic Matter, its Analogs and Simulants of Lunar Regolith Using Microwave Discharge

—In the experiment, plasma–dust clouds were obtained from the substance of the Tsarev meteorite, a simulant of lunar regolith LMS-1D and ilmenite concentrate using a microwave discharge in powder media. For each of the samples, the dynamics of the development of the discharge and the formation of a plasma–dust cloud with subsequent relaxation after the end of the microwave pulse were recorded. From the emission spectra of the plasma and the surface of a solid body, the temperatures of the gas, electrons and surface were determined. A comparison of the phase and elemental composition of the initial samples and samples after exposure to plasma showed that there is no significant change in the composition. However, scanning electron microscopy results clearly indicate spheroidization of the original angular and irregularly shaped particles. The appearance of spherical particles is also observed, the dimensions of which are larger than the linear dimensions of the particles in the original sample. The results obtained indicate the possibility of using such experiments to study chemical and plasma-chemical processes of synthesis and modification of substances under conditions of plasma–dust clouds encountered in space phenomena.

Paleostress Analysis Using Fracture Data, a Case Study of Kewa Charmula Anticline, Kurdistan Region, Northeastern Iraq

Fracture analysis was carried out through three adjacent traverses. The study area is considered a part of the Arabian Plate and geologically falls within the boundary between the Low Folded Zone and the High Folded Zone of the Western Zagros Fold-Thrust Belt in the Iraqi Kurdistan Region. Five formations are cropped out in this anticline, extending from the Late Oligocene up to the Late Miocene – Pliocene. Those formations are (Anah, Jeribe, Fatha, Injana, and Mukdadiya). In addition, identify an Oligocene unit the Kirkuk Group, represented by the (Anah Fn.) that no other studies have previously referred to, in addition, to observing the Jeribe Formation along Tilyan Gorge. About 350 fracture planes were measured for the study and classified into sets and systems concerning their relations to the three mutually perpendicular geometrical axes (tectonic axes). Tension sets are (ac), which are formed by extension along the fold axis accompanying direct compression perpendicular to the fold trend, whereas the (bc) set is supposed to be the product of relaxation that motivated the primary compressional stress. The shear systems are each of hk0, h0l, and 0kl developed successively during direct compression and subsequent relaxation episodes of each tectonic stress. The results of the paleostress analyses showed that there is a general coincidence in the direction of the major stress axis (σ1) and the minor stress axis (σ3), which were derived from the joints (fracture planes). Joints are presented as sets and systems. The analysis of joint attitudes revealed that the joints might be due to the influence of the main horizontal compression paleostress in the direction NE – SW that is responsible for folding, or they might be caused by the stretching of the outer arc for the folded layers. According to field observations and paleostress studies, the region experienced four stress stages. The first is a main compressive tectonic phase in the NE – SW direction. The second phase is the second compressive tectonic stress in the direction NW – SE. The third was a NE – SW extension tectonic phase that originated during the final uplift stage of folding and it is representative of the major fold trend. The fourth is the NW – SE extension face considered as the extension stress connected to the principal NE – SW compressive stress.

Long-term effects of non-pharmaceutical interventions on total disease burden in parsimonious epidemiological models

The recent global COVID-19 pandemic resulted in governments enacting non-pharmaceutical interventions (NPIs) targeted at reducing transmission of SARS-CoV-2. But the NPIs also affected the transmission of viruses causing non-target seasonal respiratory diseases, including influenza and respiratory syncytial virus (RSV). In many countries, the NPIs were found to reduce cases of such seasonal respiratory diseases, but there is also evidence that subsequent relaxation of NPIs led to outbreaks of these diseases that were larger than pre-pandemic ones, due to the accumulation of susceptible individuals prior to relaxation. Therefore, the net long-term effects of NPIs on the total disease burden of non-target diseases remain unclear. Knowledge of this is important for infectious disease management and maintenance of public health. In this study, we shed light on this issue for the simplified scenario of a set of NPIs that prevent or reduce transmission of a seasonal respiratory disease for about a year and are then removed, using mathematical analyses and numerical simulations of a suite of four epidemiological models with varying complexity and generality. The model parameters were estimated using empirical data pertaining to seasonal respiratory diseases and covered a wide range. Our results showed that NPIs reduced the total disease burden of a non-target seasonal respiratory disease in the long-term. Expressed as a percentage of population size, the reduction was greater for larger values of the basic reproduction number and the immunity loss rate, reflecting larger outbreaks and hence more infections averted by imposition of NPIs. Our study provides a foundation for exploring the effects of NPIs on total disease burden in more-complex scenarios.

Scaling Law for Kasha's Rule in Photoexcited Molecular Aggregates.

We study the photophysics of molecular aggregates from a quantum optics perspective, with emphasis on deriving scaling laws for the fast nonradiative relaxation of collective electronic excitations, referred to as Kasha's rule. Aggregates exhibit an energetically broad manifold of collective states with delocalized electronic excitations originating from near-field dipole-dipole exchanges between neighboring monomers. Photoexcitation at optical wavelengths, much larger than the monomer-monomer average separation, addresses almost exclusively symmetric collective states, which for an arrangement known as H-aggregate show an upward hypsochromic shift. The extremely fast subsequent nonradiative relaxation via intramolecular vibrational modes populates lower energy, subradiant states, resulting in effective inhibition of fluorescence. Our analytical treatment allows for the derivation of an approximate scaling law of this relaxation process, linear in the number of available low-energy vibrational modes and directly proportional to the dipole-dipole interaction strength between neighboring monomers.

Raman time-delay in attosecond transient absorption of strong-field created krypton vacancy

Strong field ionization injects a transient vacancy in the atom which is entangled to the outgoing photoelectron. When the electron is finally detached, the ion is populated at different excited states with part of coherence information lost. The preserved coherence of matter after interacting with intense short pulses has important consequences on the subsequent nonequilibrium evolution and energy relaxation. Here we employ attosecond transient absorption spectroscopy to measure the time-delay of resonant transitions of krypton vacancy during their creation. We have observed that the absorptions by the two spin-orbit split states are modulated at different paces when varying the time-delay between the near-infrared pumping pulse and the attosecond probing pulse. It is shown that the coupling of the ions with the remaining field leads to a suppression of ionic coherence. Comparison between theory and experiments uncovers that coherent Raman coupling induces time-delay between the resonant absorptions, which provides insight into laser-ion interactions enriching attosecond chronoscopy.

Controlling Excited State Localization in Bichromophoric Photosensitizers via the Bridging Group.

A series of photosensitizers comprised of both an inorganic and an organic chromophore are investigated in a joint synthetic, spectroscopic, and theoretical study. This bichromophoric design strategy provides a means by which to significantly increase the excited state lifetime by isolating the excited state away from the metal center following intersystem crossing. A variable bridging group is incorporated between the donor and acceptor units of the organic chromophore, and its influence on the excited state properties is explored. The Franck-Condon (FC) photophysics and subsequent excited state relaxation pathways are investigated with a suite of steady-state and time-resolved spectroscopic techniques in combination with scalar-relativistic quantum chemical calculations. It is demonstrated that the presence of an electronically conducting bridge that facilitates donor-acceptor communication is vital to generate long-lived (32 to 45 μs), charge-separated states with organic character. In contrast, when an insulating 1,2,3-triazole bridge is used, the excited state properties are dominated by the inorganic chromophore, with a notably shorter lifetime of 60 ns. This method of extending the lifetime of a molecular photosensitizer is, therefore, of interest for a range of molecular electronic devices and photophysical applications.