Attenuation Effects Research Articles

RT-SVM: Channel modeling and analysis for indoor terahertz communication scenarios

Considering the increasing demands for wireless communication networks and information system applications, the wireless sector must meet the pressing requirement for high-speed technological advances. The terahertz (THz) frequency band, spanning 0.3 to 10 THz, is of significant interest in current technological innovations and academic research in telecommunications. The THz frequency band has unique properties, including high time-resolving power (femtosecond) and low absorption. This paper proposes a THz propagation ultra-wideband (UWB) channel model and coding scheme for indoor environments starting from 0.3 THz. First, we investigated the propagation path loss model by considering the effects of transmitter dimensions, molecular absorption, and attenuation as functions of frequency and distance. We developed models for power propagation delay, multiple input multiple output (MIMO) systems and discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) response channels. Using the standard Saleh-Valenzuela model combined with Ray-tracing (RT-SVM), we studied the transmission of THz signals in indoor scenarios. We introduced physical parameters relevant to the THz indoor channel, such as line-of-sight (LoS) path loss, power distributions, temporal and spatial properties, and associations between THz multipath properties. These parameters were integrated with the RT-SVM channel model and applied to THz indoor communication. Numerical simulations demonstrate that the proposed hybrid channel model enhances THz system performance and outperforms traditional statistical and geometric-based stochastic channel models in terms of temporal and spatial dimensions, contributing to frequency loss variations.

Changing the resonant nucleus by altering the static field, compensation of [formula omitted] and [formula omitted] effects in T2 and T2* measurements of porous media

Multinuclear 1H, 13C, and 23Na magnetic resonance (MR) has many advantages for studying porous media systems containing hydrocarbons and brine. In recent work, we have explored changing the nucleus measured, keeping the Larmor frequency constant, by changing the static magnetic field B0. Increasing the static B0 field distorts the field in the pore space due to susceptibility mismatch between the matrix and pore fluid. Distortion of the magnetic field in the pore space scales with the applied static field. The gradients that result from the spatial variation of the distorted field will also scale with B0. The equations that describe the inhomogeneous broadening in T2* show that the MR result depends on γB0. The diffusion through internal field gradients effect on T2 depends on the product of γ and G, with G depending on B0.Increasing the static field to bring a nucleus with lower γ into resonance at the same frequency will result in the products γB0 and γG being constant, and therefore, inhomogeneous broadening and diffusion attenuation effects in porous media are predicted to be constant. We explore the T2* hypothesis with 23Na and 1H measurements of brine in porous reservoir core plugs. We explore the diffusion through internal field gradients effect hypothesis with 1H and 13C measurements of decane saturated glass beads.The nuclei chosen for study: 1H, 13C, and 23Na are the three most important nuclei for studies of fluids (brine and hydrocarbons) in reservoir core plugs. These three nuclei have a common resonance frequency of 33.7 MHz at static fields of 0.79 T, 3.19 T, and 2.99 T, respectively. All three fields are readily achieved with our variable field superconducting magnet.

Navigating Greenhouse Gas Emission Unknowns: A Hydroacoustic Examination of Mediterranean Climate Reservoirs

AbstractInland aquatic systems, such as reservoirs, contribute substantially to global methane (CH4) emissions; yet they are among the most uncertain contributors to the total global carbon budget. Reservoirs generate significant amounts of CH4 within their bottom sediment, where the gas is stored and can easily escape via ebullition. Due to the large spatial and temporal variability associated with ebullition, CH4 fluxes from these aquatic systems are challenging to quantify. To address these uncertainties, six different water storage reservoirs, with average flux rates ranging between 20 and 678 mg CH4 m−2 d−1, were hydro‐acoustically surveyed using a previously established technique to investigate the spatial variability of free gas stored at the sediment surface that could be released as bubbles. Sediment samples and vertical profiles of temperature and dissolved oxygen were also collected to understand their respective influences on sediment gas formation. We found that the established relation used to determine sediment gas storage via the sonar technique, which relied solely on acoustic backscatter (Svmax), tended to underestimate gas storage in shallower, siltier sediment zones and overestimate gas storage in coarser (>2 mm) sediment zones. In response, we introduce an improved model, incorporating gas and sediment type as correction factors for gas attenuation effects on Svmax values. The extended model is able to elucidate patterns within the gas volume data, revealing clearer trends across different sediment types. This research provides valuable data and methodological insights that can enhance the accuracy of greenhouse gas modeling and budget assessments for reservoirs.

Continuous near-perfect sound absorption of a slit-resonator acoustic metastructure

A novel slit-resonator acoustic metastructure (SRAM) composed of Helmholtz resonators and porous materials is proposed to achieve a continuous perfect sound absorption at 200–3000 Hz. The Helmholtz resonator utilizes the resonance effect for low-frequency acoustic energy attenuation, and when its neck is small enough, it can be considered as an air slit. The air slit acts as a channel, from which most acoustic waves enter the metastructure and are absorbed by porous materials. Porous materials absorb high-frequency sound waves through thermoviscous dissipation. Unlike traditional filling forms, porous materials are filled around the air slits. To analyze the acoustic performance of this metamaterial, theoretical models and finite element models are developed and experimentally verified. The SRAM with melamine foam and rock wool can reach an absorption effect better than 0.5 at 331–3000 Hz and reaches a peak of 0.946 at 501 Hz with a thickness of 50 mm. Using the genetic algorithm, the parameters of SRAM are optimized for efficient sound absorption over a wider bandwidth. The optimized SRAM obtains an absorption coefficient of 0.8 in the range of 400–3000 Hz with a thickness of 50 mm. This study provides a new method of low-frequency ultra-broadband sound absorption.

Alcohol consumption and preference in female rats induced by reward downshift reveals sex generality of the modulatory role of physical activity.

Increased voluntary consumption of alcohol has been demonstrated in male rats exposed to frustrative reward downshift (the emotional self-medication effect). Access to a wheel for voluntary running abolished this effect in male rats, suggesting an attenuating effect of physical exercise on the negative affect induced by reward downshift and its consequences on drug intake. The present study analyzed this effect in female rats. Sixty-four food-deprived female Wistar rats received 32% sucrose [4% (Experiment 1) or 2% (Experiment 2) in controls] during 10, 5-min preshift sessions followed by 4% (Experiment 1) or 2% (Experiment 2) sucrose during 5 postshift sessions. Immediately after each consummatory session, animals were exposed to a 2-h, two-bottle preference test involving 32% alcohol vs. water. Half of the animals also had access to a running wheel during the preference test. The results showed (a) lower sucrose consumption in the downshifted groups (32-4% and 32-2%) compared to the unshifted controls (4-4% and 2-2%, respectively); (b) higher alcohol preference in downshifted groups without access to a wheel compared with downshifted groups with access to the wheel (Experiments 1 and 2); and (c) increased alcohol intake (g/kg) after experiencing reward downshift in animals without access to the wheel (Experiment 1). Voluntary wheel running thus reduced alcohol intake in female rats experiencing reward downshift. These findings are comparable to previous results reported in male rats and support the usefulness of physical exercise to prevent alcohol self-medication induced by frustrative nonreward.

Evaluation of the performance and effect of steel fiber reinforced cellular concrete for underwater blast protection under contact explosion loading

The reinforced concrete structure is more likely to be destroyed under the action of underwater explosion load, which makes the overall structure have the risk of instability. The purpose of this paper is to study the underwater anti-explosion protection performance of steel fiber reinforced cellular concrete protective layer. The FEM-SPH coupling method was used to study the underwater damage process, dynamic response, failure mode and protection effect of the protected structure strengthened by eight different proportions of protective layers. The results show that the addition of steel fiber reinforced cellular concrete protective layer can effectively improve the anti-explosion performance of the protected structure, and its anti-explosion performance is directly related to the volume fraction of steel fiber in the protective layer. Under different ratio protection schemes, the total energy absorption and protection rate of the protective layer increase first and then decrease with the increase of the volume fraction of steel fiber in the protective layer, while the peak pressure of the protected structure at the measuring point and the failure volume rate of the whole structure decrease first and then increase. Among them, the underwater wave attenuation and energy consumption effect of SAP10S15 protective layer is the most prominent, and its total energy absorption is 20 % higher than that of other protective layers. Under this ratio protection scheme, the shock wave pressure of the protected structure is greatly attenuated, and the peak pressure of each measuring point is reduced by about 35.8 %, 37.9 %, 23.7 %, 27.9 % and 35.1 % respectively compared with the unprotected scheme. The damage degree of the protected structure under the SAP10S15 ratio protection scheme is significantly reduced. The failure volume rate and damage index are 8.03 % and 0.21, respectively, which are 37.7 % and 42.5 % lower than those of the unprotected scheme. The damage level is reduced from serious damage to moderate damage. In addition, the damage grade prediction curve of the protected structure is constructed, and the predicted value of the curve is in good agreement with the simulation results, which can provide a reference for the rapid evaluation of the underwater explosion-proof performance of the steel fiber reinforced cellular concrete protective layer.

Azo-linked 5-ASA-coumarin prodrug: Fluorescent tracking for colonic drug release in UC treatment

Theranostic prodrugs that enable real-time, non-invasive monitoring of drug release and biodistribution are highly desirable for optimizing therapeutic efficacy and guiding personalized medication. Herein, we report a colon-targeted theranostic prodrug system (P1) for the simultaneous delivery and tracking of 5-aminosalicylic acid (5-ASA) in the treatment of ulcerative colitis (UC). P1 comprises a fluorescent 7-amino-4-methylcoumarin (7-AMC) reporter covalently linked to 5-ASA via an azo bond, which quenches the fluorescence of 7-AMC until P1 is activated by azoreductases in the colonic microenvironment. This selective activation triggers the release of 5-ASA and the revival of 7-AMC fluorescence, enabling real-time monitoring of drug delivery. To improve the solubility and targeted delivery of P1, it was encapsulated within polymeric micelles (PM) that selectively adhere to the positively charged, inflamed colonic tissues. In vitro studies confirmed the stability, biocompatibility, and selective activation of P1 under simulated colonic conditions. Notably, in a mouse model of UC, the P1-loaded PM achieved targeted delivery of 5-ASA to the inflamed colon, resulting in effective attenuation of colitis symptoms. Importantly, the in situ activation of P1 allowed for the real-time, non-invasive visualization of drug release and biodistribution, providing valuable insights for treatment optimization. This theranostic prodrug approach offers a promising strategy for the simultaneous therapy and tracking of 5-ASA delivery in UC treatment, with the potential to facilitate personalized medication and improve therapeutic outcomes.

Optical, thermal, and radiation shielding characterization of bismuth-modified zinc-lithium-tungsten-borate glass

Abstract This study examines the optical, thermal, and radiation attenuation properties of zinc-tungsten-lithium-borate glass modified with Bi2O3, synthesized using melt-quench techniques. The resulting glass samples display a significant physical property, with density increasing from 3.22 g/cm³ to 4.84 g/cm³ as Bi2O3 concentration increase from 2 to 16 mol%. The optical band gap narrows from 2.9 eV to 2.55 eV, while the refractive index increases from 2.42 to 3.49, indicating a shift in absorption to lower energy levels. Higher Bi2O3 concentrations reduce optical non-linearity while enhancing the linear optical properties of the synthesized glasses. The formation of orthoborate anions suggests that Bi3+ ions in the glasses act as network modifiers, disrupting the borate framework and introducing structural disorder. Additionally, thermal properties, including glass transition temperature (T_g), crystallization temperature (T_c), and melting temperature (T_m), decrease with increasing Bi2O3 concentration. The radiation shielding effectiveness is significantly improved, with the linear attenuation coefficient (LAC) increasing from 0.56 cm⁻¹ to 1.35 cm⁻¹ at 0.284 MeV and from 0.127 cm⁻¹ to 0.186 cm⁻¹ at 2.506 MeV as Bi2O3 content rises from 2 mol% to 16 mol%. For a glass thickness of 1 cm, the radiation protection efficiency reaches approximately 74% for a photon energy of 0.284 MeV in the sample doped with 16 mol% Bi2O3. The glass's remarkable combination of high transparency and effective radiation attenuation, positions it as a promising option for radiation shielding applications.

Study on noise reduction and structural optimization of ventilated bio-metamaterial plates for acoustic applications

This study focuses on the noise reduction performance and structural optimization of ventilated metamaterial plates designed for bio-acoustic applications, where effective sound attenuation and ventilation are both crucial. Traditional soundproofing materials, which rely on mass and thickness, are inadequate for bio-acoustic environments that require lightweight and compact solutions. In contrast, bio-acoustic metamaterials use resonance effects to attenuate sound while maintaining necessary airflow selectively. This research evaluates multiple metamaterial plate configurations through computational simulations and experimental testing, examining their performance in terms of Sound Transmission Loss (STL), airflow rates, and von Mises stress. The results reveal that Plate Configuration 1 offers the highest STL at 39.14 dB but at the cost of lower airflow efficiency (0.69 m3/s) and increased structural stress (24.83 MPa). Plate Configuration 2 achieves the best airflow efficiency (0.82 m3/s) but with lower noise reduction (STL of 35.42 dB). Plate Configuration 3 provides a balanced performance, with moderate noise attenuation (STL of 37.89 dB), good airflow (0.75 m3/s), and structural stability (von Mises stress of 22.12 MPa). The study concludes that bio-acoustic metamaterials can be effectively optimized for different bio-acoustic applications by carefully tuning their geometry, making them suitable for eco-acoustics, wildlife monitoring, and medical devices where noise control and airflow are critical.

Improving Building Floor Acoustics with Innovative Inorganic Sound Insulation Coating

Floor impact sound insulation is essential for improving living environments and has become a mandatory requirement for green buildings in Southern China. This study introduces an innovative inorganic sound insulation coating technology for enhancing building floor acoustic performance. Through comprehensive laboratory experiments and field tests, we evaluated inorganic coatings of 3 mm and 5 mm thickness, comparing their performance against traditional methods, including organic coatings and soundproof mortar. Standardized impact sound pressure level measurements, conducted in accordance with the China GB/T 50121 standard, demonstrated significant acoustic improvements. Laboratory testing revealed impact sound reductions of 6–7 dB and 9–10 dB for the 3 mm and 5 mm inorganic coatings, respectively, while field applications of the 3 mm coating achieved an average reduction of 14.3 dB. The inorganic coating exhibited superior performance characteristics compared to both organic coatings and soundproof mortar in terms of sound insulation efficiency, fire resistance, and application feasibility, demonstrating particularly effective attenuation in the mid- to high-frequency range. This investigation presents an innovative, cost-effective, and environmentally sustainable solution for improving floor sound insulation in green buildings.

MMD-Net: Image domain multi-material decomposition network for dual-energy CT imaging.

Multi-material decomposition is an interesting topic in dual-energy CT (DECT) imaging; however, the accuracy and performance may be limited using the conventional algorithms. In this work, a novel multi-material decomposition network (MMD-Net) is proposed to improve the multi-material decomposition performance of DECTimaging. To achieve dual-energy multi-material decomposition, a deep neural network, named as MMD-Net, is proposed in this work. In MMD-Net, two specific convolutional neural network modules, Net-I and Net-II, are developed. Specifically, Net-I is used to distinguish the material triangles, while Net-II predicts the effective attenuation coefficients corresponding to the vertices of the material triangles. Subsequently, the material-specific density maps are calculated analytically through matrix inversion. The new method is validated using in-house benchtop DECT imaging experiments with a solution phantom and a pig leg specimen, as well as commercial medical DECT imaging experiments with a human patient. The decomposition accuracy, edge spreading function, and noise power spectrum are quantitativelyevaluated. Compared to the conventional multiple material decomposition (MMD) algorithm, the proposed MMD-Net method is more effective at suppressing image noise. Additionally, MMD-Net outperforms the iterative MMD approach in maintaining decomposition accuracy, image sharpness, and high-frequency content. Consequently, MMD-Net is capable of generating high-quality material decompositionimages. A high performance multi-material decomposition network is developed for dual-energy CTimaging.

Climate policy and carbon leakage: Evidence from the low-carbon city pilot program in China

The low-carbon city pilot (LCCP) policy, aimed at promoting the transformation of cities towards low-carbon practices, is an important action for China to mitigate climate change. Though this climate policy brings positive effects in many aspects, the issue of potential carbon leakage due to regional disparity has been overlooked. This paper introduces a novel approach by employing the spatial DID model and prefecture-level city data to assess the LCCP policy and its implications for carbon leakage. The innovative aspect lies in its spatially differentiated analysis, which reveals that while the LCCP policy effectively reduces carbon emissions of local pilot cities, it simultaneously triggers carbon leakage to neighboring non-pilot cities, with the leakage effects diminishing with increasing distance. Additionally, this study uncovers that carbon leakage risks are mitigated when multiple pilot cities are geographically clustered, enhancing the overall effectiveness of the policy. Finally, the impact channel analysis uniquely identifies that carbon leakage results from the inter-city relocation of high-carbon industries, such as manufacturing, which exhibits spatial attenuation and temporal lag effects. This study advances the understanding of low-carbon city pilot programs and provides valuable insights for mitigating carbon leakage risks.

Effect of the Infill Density on 3D-Printed Geometrically Graded Impact Attenuators.

Three-dimensional printing is widely becoming prevalent in various industries, including the automotive sector. As this technology advances, critical structures subjected to impact loads may also be produced using additive manufacturing. A key parameter in this technique is the infill density of the printed geometry, which directly affects mechanical properties such as strength, stiffness, and ductility. Functionally graded layouts present themselves as one of the best techniques to design effective impact attenuators. The present work combines these techniques and parameters to evaluate the behaviour of geometrically graded impact attenuators produced through additive manufacturing, with different infill densities for polylactic acid (PLA) and polycarbonate (PC) materials. The results obtained show an increase in the mechanical strength for both materials and all the infill densities when compared to reference quasi-static results.

Numerical Investigation of Network-Based Shock Wave Propagation of Designated Methane Explosion Source in Subsurface Mine Ventilation System Using 1D FDM Code

In coal mining operations, methane explosions constitute a severe safety risk, endangering miners’ lives and causing substantial economic losses, which, in turn, weaken the production efficiency and economic benefits of the mining industry and hinder the sustainable development of the industry. To address this challenge, this article explores the application of decoupling network-based methods in methane explosion simulation, aiming to optimize underground mine ventilation system design through scientific means and enhance safety protection for miners. We used the one-dimensional finite difference method (FDM) software Flowmaster to simulate the propagation process of shock waves from a gas explosion source in complex underground tunnel networks, covering a wide range of scenarios from laboratory-scale parallel network samples to full-scale experimental mine settings. During the simulation, we traced the pressure loss in the propagation of the shock wave in detail, taking into account the effects of pipeline friction, shock losses caused by bends and obstacles, T-joint branching connections, and cross-sectional changes. The results of these two case studies were presented, leading to the following insights: (1) geometric variations within airway networks exert a relatively minor influence on overpressure; (2) the positioning of the vent positively contributes to attenuation effects; (3) rarefaction waves propagate over greater distances than compression waves; and (4) oscillatory phenomena were detected in the conduits connecting to the surface. This research introduces a computationally efficient method for predicting methane explosions in complex underground ventilation networks, offering reasonable engineering accuracy. These research results provide valuable references for the safe design of underground mine ventilation systems, which can help to create a safer and more efficient mining environment and effectively protect the lives of miners.

EXPRESS: Individual control of input rate improves recall of spoken discourse by adult users of cochlear implants: An exploratory study.

Although cochlear implants (CI) successfully replace the sense of hearing, they do not restore natural hearing. Still, CI users adapt to this novel signal, reaching meaningful levels of speech recognition in clinical tests that focus on repetition of words and short sentences. However, many patients who score above average in clinical speech perception tests complain that everyday speech interactions are both difficult and cognitively draining. In part this difficulty may be due to the naturally rapid pace of everyday discourse. We report a study in which 12 CI users aged 23 to 77, recalled multi-sentence discourse presented without interruption, or in the condition of interest, when passages were paused at major linguistic boundaries, with participants given control of when to initiate the next segment. Comprehension of the discourse structure was based on a formalized representational system that organizes discourse elements hierarchically to index the relative importance of different elements to the overall understanding of the discourse. Results showed (a) better recall when CI users were allowed to control the discourse pace, (b) an overall effect of aging, with older CI users recalling discourse less accurately, (c) better recall for passages with higher average inter-word predictability, (d) a "semantic hierarchy effect" reflected by better recall of main ideas versus minor details, (e) an attenuation of the semantic hierarchy effect for low predictability passages. Results underscore the benefits of extra processing time in addressing CI listening challenges and highlight the limited ecological validity of single-word or single-sentence speech recognition tests.

EXTH-31. TARGETINGMIR-19B/PPP2R5E REGULATORY AXIS TO MAXIMISE ALKYLATING AGENT EFFICACY: A NEW AVENUE TO COUNTERACT TEMOZOLOMIDE RESISTANCE IN RECURRENT GLIOBLASTOMAS

Abstract Glioblastoma, IDH-wildtype (GBM), notorious for its inevitable recurrence despite aggressive multi-modal standard of care, presents a pressing need for novel treatment paradigms. The extensive DNA damage caused by the frontline DNA alkylating agent, temozolomide (TMZ) is counteracted by intricate or acquired survival mechanisms. Through functional microRNA screens we identified miR-19b-overexpressing clones possessing extra fitness in presence of escalating doses of TMZ. Our study uncovers a previously unrecognized TMZ resistance mechanism governed by miR-19b. Notably, miR-19b attenuation intensified DNA damage response and CHEK1 and CHEK2 phosphorylation, instigating persistent DNA lesions and consequently priming GBM cells for heightened TMZ cytotoxicity. Mechanistically, we showed that miR-19b exerts its function by targeting PPP2R5E, a subunit of protein phosphatase PP2A, frequently downregulated in GBM. We uncovered that the elevated DNA damage response in the miR-19b-attenuated cells was a consequence of enhanced nuclear and mitochondrial ROS production. This in turn, induced ROS-mediated senescence, and an intriguing susceptibility to ferroptosis, possibly due to increased ROS-mediated lipid peroxidation. Of note, all these phenotypes were reversed in GBM cells with concomitant miR-19b and PPP2R5E attenuation, demonstrating that miR-19b exerts its role in TMZ resistance by targeting PPP2R5E. In line with this finding, an orthotopic human-derived glioblastoma stem cell xenograft model confirmed that PPP2R5E attenuation not only decreases TMZ cytotoxicity in the brain, but also at the spinal metastatic location. Consistently, treating cells with the PP2A-activating drug FTY720 or knocking down endogenous PP2A-inhibiting proteins mirrored the effects of miR-19b attenuation in enhancing TMZ cytotoxicity. This intricate interplay between miR-19b and PPP2R5E underscores a novel strategy to modulate the TMZ response, highlighting promising results in our pre-clinical models. In conclusion, our findings advocate for the therapeutic targeting of the miR-19b/PPP2R5E regulatory axis as a potential novel strategy in the pursuit of effective therapeutic interventions for the formidable recurrent GBM tumours.

The Kernel Density Estimation Technique for Spatio-Temporal Distribution and Mapping of Rain Heights over South Africa: The Effects on Rain-Induced Attenuation

The devastating effects of rain-induced attenuation on communication links operating above 10 GHz during rainy events can significantly degrade signal quality, leading to interruptions in service and reduced data throughput. Understanding the spatial and seasonal distribution of rain heights is crucial for predicting these attenuation effects and for network performance optimization. This study utilized ten years of atmospheric temperature and geopotential height data at seven pressure levels (1000, 850, 700, 500, 300, 200, and 100 hPa) obtained from the Copernicus Climate Data Store (CDS) to deduce rain heights across nine stations in South Africa. The kernel density estimation (KDE) method was applied to estimate the temporal variation of rain height. A comparison of the measured and estimated rain heights shows a correlation coefficient of 0.997 with a maximum percentage difference of 5.3%. The results show that rain height ranges from a minimum of 3.5 km during winter in Cape Town to a maximum of about 5.27 km during the summer in Polokwane. The spatial variation shows a location-dependent seasonal trend, with peak rain heights prevailing at the low-latitude stations. The seasonal variability indicates that higher rain heights dominate in the regions (Polokwane, Pretoria, Nelspruit, Mahikeng) where there is frequent occurrence of rainfall during the winter season and vice versa. Contour maps of rain heights over the four seasons (autumn, spring, winter, and summer) were also developed for South Africa. The estimated seasonal rain heights show that rain-induced attenuations were grossly underestimated by the International Telecommunication Union (ITU) recommended rain heights at most of the stations during autumn, spring, and summer but fairly overestimated during winter. Durban had a peak attenuation of 15.9 dB during the summer, while Upington recorded the smallest attenuation of about 7.7 dB during winter at a 0.01% time exceedance. Future system planning and adjustments of existing infrastructure in the study stations could be improved by integrating these localized, seasonal radio propagation data in link budget design.

Is Greener Better? Quantifying the Impact of a Nature Walk on Stress Reduction Using HRV and Saliva Cortisol Biomarkers.

The physiological impact of walking in nature was quantified via continuous heart rate variability (HRV), pre- and post-walk saliva cortisol measures, and self-reported mood and mindfulness scores for N = 17 participants who walked "The Green Road" at Walter Reed National Military Medical Center in Bethesda, Maryland. For N = 15 of the participants, HRV analysis revealed two main groups: group one individuals had a 104% increase (mean) in the root mean square standard deviation (RMSSD) and a 47% increase (mean) in the standard deviation of NN values (SDNN), indicating an overall reduction in physiological stress from walking the Green Road, and group two individuals had a decrease (mean) of 42% and 31% in these respective HRV metrics, signaling an increase in physiological stresses. Post-walk self-reported scores for vigor and mood disturbance were more robust for the Green Road than for a comparable urban road corridor and showed that a higher HRV during the walk was associated with improved overall mood. Saliva cortisol was lower after taking a walk for all participants, and it showed that walking the Green Road elicited a significantly larger reduction in cortisol of 53%, on average, when compared with 37% of walking along an urban road. It was also observed that the order in which individuals walked the Green Road and urban road also impacted their cortisol responses, with those walking the urban road before the Green Road showing a substantial reduction in cortisol, suggesting a possible attenuation effect of walking the Green Road first. These findings provide quantitative data demonstrating the stress-reducing effects of being in nature, thus supporting the health benefit value of providing access to nature more broadly in many settings.

Atractylodes macrocephala Rhizoma alleviates blood hyperviscosity induced by high-fat, high-sugar, and high-salt diet by inhibiting gut-liver inflammation and fibrinogen synthesis

Ethnopharmacological relevanceUnhealthy dietary patterns and lifestyle changes have been linked to increased blood viscosity, which is recognized as an important pathogenic factor in cardiovascular and cerebrovascular diseases. The underlying mechanism may involve chronic inflammation resulting from intestinal barrier disruption induced by unhealthy diets. The rhizome of Atractylodes macrocephala Koidz. (Called Baizhu in China), is a well-used “spleen-reinforcing” traditional Chinese medicinal herb used for thousands of years. Previous research has demonstrated its multiple gastrointestinal health benefits and its ability to regulate metabolic disorders. However, the effects of Baizhu on blood hyperviscosity induced by long-term unhealthy diets remain unclear. Aim of the studyThis study aimed to investigate the effects of the aqueous extract of Baizhu on blood hyperviscosity induced by unhealthy diet and to explore the possible mechanisms. Materials and methodsThe blood hyperviscosity model in SD rats was established utilizing a high-fat, high-sugar, and high-salt diet (HFSSD). Subsequently, the rats underwent a twelve-week intervention with varying doses of Baizhu and a positive control. To evaluate the efficacy of Baizhu on blood hyperviscosity in model rats, we measured behavioral index, hemorheological parameters, inflammatory cytokines, hematology, adhesion molecules, as well as biochemical indicators in serum and liver. We also assessed the pathological states of the colon and liver. Furthermore, Western blotting, ELISA, IHC, and qRT-PCR were used to determine the effect of Baizhu on the IL-6/STAT3/ESRRG signaling pathway and FIB synthesis. ResultsThe intervention of Baizhu showed evident attenuating effects on blood viscosity and microcirculation disorders, and exhibit the capacity to moderately modulate parameters including grip, autonomous activities, vertigo time, TC, TG, LDL-c, inflammatory factors, adhesion factors, hematological indicators, etc. At the same time, it reduces liver lipid droplet deposition, restores intestinal integrity, and lowers LPS level in the serum. Subsequent experimental results showed that Baizhu downregulated the expression of TLR4 and NF-κB in colon tissue, as well as the expression of IL-6, TLR4, p-JAK2, p-STAT3, and ESRRG in liver tissue. Finally, we also found that Baizhu could regulate the levels of FIB in plasma and liver. ConclusionBaizhu protects HFSSD-induced rats from blood hyperviscosity, likely through repairing the intestinal barrier and inhibiting LPS/TLR4-associated liver inflammatory activation, thus suppressing FIB synthesis through the downregulation of IL-6/STAT3/ESRRG pathway.

Constraints on Acoustic Wave Energy Fluxes and Radiative Losses in the Solar Chromosphere from Non-LTE Inversions

Accurately assessing the balance between acoustic wave energy fluxes and radiative losses is critical for understanding how the solar chromosphere is thermally regulated. We investigate the energy balance in the chromosphere by comparing deposited acoustic flux and radiative losses under quiet and active solar conditions using non–local thermodynamic equilibrium inversions with the Stockholm Inversion Code. To achieve this, we utilize spectroscopic observations from the Interferometric BIdimensional Spectrometer in the Na i 5896 Å and Ca ii 8542 Å lines and from the Interface Region Imaging Spectrograph in the Mg ii h and k lines to self-consistently derive spatially resolved velocity power spectra and cooling rates across different heights in the atmosphere. Additionally, we use snapshots of a three-dimensional radiative magnetohydrodynamics simulation to investigate the systematic effects of the inversion approach, particularly the effect of attenuation on the velocity power spectra and the determination of the cooling rates. The results indicate that inversions potentially underestimate acoustic fluxes at all chromospheric heights while slightly overestimating the radiative losses when fitting these spectral lines. However, even after accounting for these biases, the ratio of acoustic flux to radiative losses remains below unity in most observed regions, particularly in the higher layers of the chromosphere. We also observe a correlation between the magnetic field inclination in the photosphere and radiative losses in the low chromosphere in plage, which is evidence that the field topology plays a role in the chromospheric losses.