bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation study on indoor thermal environment improvement in multi-story buildings assisted by natural ventilation
Authors: Bai Yufu , Zhao Ningjing , Long Tianhe , Li Yongcai
Published: August 2022

Buoyancy-driven natural ventilation has the potential to improve the indoor thermal environment without any energy consumption. In this study, the applicability of the dimensionless area design method was studied, and the airflow rate and excess temperature deviation of rooms on different floors were verified. The results demonstrate that the airflow rates on the first, second and third floors are 887.68, 861.84 and 820.93 m3/h, respectively, and the corresponding airflow rates per capita are 88.77, 86.18 and 82.09 m3/h, respectively. In addition, the average indoor temperatures on the first, second and third floors are 298.78, 299.05 and 299.58 K, respectively, with corresponding excess temperatures of 5.72, 5.99 and 6.52 K. The deviation of airflow rate in the room is within the range of 0.59%-4.2%, indicating that the dimensionless area design method is suitable for designing naturally ventilated buildings.
Mean Wind Velocity Distribution at Near-ground Level Obtained Through Field Measurements
Authors: Zhong Jiading , Liu Jianlin , Liang Guoming
Published: August 2022

Mean wind velocity profiles enable researchers to conduct efficient and accurate analyses of a wide variety of urban microclimatic problems, such as pollution dispersion, heat island effect and pedestrian wind comfort. However, due to the heterogeneity in the complex urban context, the wind profile at near-ground level within the real urban context remains insufficiently investigated. The present study aims to measure the near-ground level mean wind profiles in an industrial park. To this practical end, a sonic anemometer was equipped to a height adjustable bar on a mobile measurement platform. Through adjusting the sonic anemometer’s height, the mean wind velocities at different heights of the near-ground level were measured. Results indicate that the mean wind velocities’ variation along the near-ground heights measured at the site exposed to open and flat upwind areas can be reasonably captured by the power-law profile, while the other two conventional profiles, i.e. the log-law and the exponential profiles, show different levels of inaccuracy.
Real-time visualization of indoor aerosol dispersion based on a new Markov chain model
Authors: Zeng Chenni , Mei Xiong , Yi Yi , Jiang Changwei
Published: August 2022

Accurate acquisition of real-time aerosol distribution indoors is crucial to both estimating real-time infection risk of indoor respiratory infectious diseases as well as rapidly optimizing the ventilation effectiveness of building structure during the design stage. Real-time prediction of aerosol distribution can hardly be achieved by CFD model due to its iterative solution strategy, while the Markov chain model can greatly reduce computing time by implementing the non-iterative state transfer process. In this study, a real-time visualization algorithm for aerosol dispersion in limited space is developed based on the Markov chain principle and pre-solved flow field. Then the reliability of the proposed algorithm is verified by experimental data. An interactive user interface is further constructed based on the validated algorithm to realize real-time simulation of the dynamic release process of multiple indoor pollution sources. Results show that the simulation outcomes agree well with the experimental validation data, and the dynamic real-time distribution of aerosols can be well visualized for steady-state airflow. The present study aims to provide a new effective prediction method for real-time visualization of indoor pollutant dispersion and rapid evaluation of the impacts of building structure on ventilation effectiveness.
Reconstruction of uncertain parameters in a multizone model based on contam and bayesian inference
Authors: Li Fei , Zhuang Junyi , Zhang Jie , Li Mo , Cai Hao , Cao Xiaodong
Published: August 2022

The prediction of contaminant distribution in multi-zone environment is critical for ensuring indoor personnel health and making an optimistic ventilation strategy. However, the input of uncertainty parameters (flow coefficients, flow exponents, etc.) has a significant impact on the predicted pollutant concentrations. In this study, we proposed a reconstruction method to achieve parameter estimation for the multi-zone model. MATLAB codes was programmed to call CONTAM engine to accomplish pollutant transport simulation in a multi-zone scaled building model. Then a Bayesian inference algorithm compiled in MATLAB codes was applied to determine the unknown parameters iteratively. Finally, multi-zone scaled experiments with different forms of pollutant sources were employed to validate the reconstruction method. The results showed that the predicted concentrations with the reconstructed parameters agreed well with the measured data in the constant source (CS) experiment. While, for the dynamic source (DS) experiment, the predicted concentrations had some discrepancies with the measured data.
CFD modeling of a self-oscillatory airflow regime in the test ventilated room with plane supply opening
Authors: Ivanov Nikolay , Zasimova Marina , Stepasheva Ekaterina , Kudryavtseva Vasilisa
Published: August 2022

The current contribution presents the results of numerical simulation of the airflow and heat transfer in a model room of rectangular shape ventilated with a single plane jet under the conditions of the experiment by Mataoui et al. (2001). The 2D and 3D unsteady Reynolds-averaged Navier-Stokes approaches were used. Numerical solutions were obtained with the CFD package ANSYS Fluent based on the finite volume method with the cell-centered variable arrangement. The position of the air supply nozzle corresponds to the self-oscillatory experimental conditions. The results of the computational data validation are reported. Effects of the low-frequency velocity oscillations on the heat transfer parameters are discussed.
Integration of airflow zonal model and building energy simulation for large space buildings
Authors: Lu Yanyu , Chen Zhifu , Hu Site , Liu Jing
Published: August 2022

Contemporarily, large spaces prevail in many diverse and complex buildings, but meanwhile, incur more demanding requirements about thermal comfort and energy saving. Conventional building energy simulation (BES) computes the whole building based on the assumption of quiescent and uniform air. By contrast, computational fluid dynamics (CFD) can obtain rich and detailed airflow results, but consumes tremendous computational time and resources. Then, the zonal model as an intermediate method between these two models has gradually approached to the visual field of the public, which plays an important role in rapidly predicting the overall thermal stratification of large spaces. Therefore, this paper discussed a practical and automatic method of integration of the zonal model and BES. In this way, annual dynamic energy consumption of large space buildings can be analysed, which will exhibit significant potential in the engineering field, especially at primary design stage.
Ventilation and Low-cost Strategies on Mitigating COVID-19 Infection Disease Transmission in Indoor Environment
Authors: Ren Chen , Cao Shi-Jie
Published: August 2022

During the normalization phase of COVID-19 epidemic, it is gradually reverted to use building space, especially for office. Prevention of airborne pollutant has emerged as a major challenge. Ventilation strategies can mitigate the spread of airborne disease in indoor environment, such as increasing ventilation rate, modifying ventilation mode, etc. The larger ventilation rate can lead to higher energy consumption may not effectively reduce infection risk. The potential of ventilation modes for COVID-19 control should be explored. Furthermore, it is necessary to adopt low-cost strategies, such as physical barrier, to increase the prevention efficiency while combining the ventilation system. This study was to investigate the impact of physical barrier on the spread of particles and infection risk in an office with a sufficient ventilation rate, and then compare different ventilation strategies, including mixing ventilation (MV), zone ventilation (ZV), stratum ventilation (SV) and displacement ventilation (DV), for the optimal one. The simulation model was mainly used in this work and validated by the experiment to show a good agreement with the model prediction. The results showed that (1) the SV showed greater performance in mitigating infection disease spread than MV, ZV and DV, with a minimum infection risk of 13%; (2) a barrier height of at least 60 cm above the desk surface is needed to effectively prevent the transmission of viruses with the risk of infection reduced by about 72%. This work can provide a reference for development of ventilation strategies as well as low-cost prevention interventions in public space oriented the prevention of COVID-19.
Aerosol transmission risk of COVID-19 when passengers move slowly in a line at the airport terminal
Authors: Zhao Yu , Feng Yao
Published: August 2022

The airport terminal with high numbers of occupied passengers has potentially become high risk region for aerosol transmission of COVID-19. In this paper, the Eulerian-Lagrangian approach and realizable k–ε turbulence model is used to numerically simulate the airflow organization and aerosol transmission when passengers move slowly in a line. During the aerosol transmission period, evaporation is also enrolled as it is a key factor influencing particle size distribution at the beginning of aerosol transmission from the human. In addition, the process of passenger moving in the airport terminal is realized by employing dynamic mesh algorithms. The results of the study show that people who are behind the infected person during the queuing movement have a higher risk of infection than those who are in front. In addition, the disturbance of people walking has an important influence on the distribution of aerosols.
Numerical Simulation of radon migration influenced by heat-moisture coupled transfer in aerated concrete wall under different outdoor temperature and humidity conditions
Authors: Chen Yuanchao , Xie Dong , Chen Guojie , Dai Shiliang , Liu Suyao
Published: August 2022

It is of great significance for indoor radon radiation protection to study the mechanism of radon migration systematically caused by heat-moisture coupled transfer in building walls. The radon migration model of porous building walls under the influence of the heat-moisture coupled model is built. On the base of it, four types of different temperature and humidity conditions, including high temperature and high humidity, high temperature and low humidity, low temperature and high humidity and low temperature and low humidity, and the real ambient temperature, relative humidity conditions in a southern city of China in July, are set for the numerical simulation. The migration mechanism of the radon through the wall influenced by outdoor temperature and humidity conditions, including its emanation, diffusion and condensation, is studied by numerical simulation, and the main factors leading the results are analyzed, which provides some reference for indoor radon radiation protection.
Study on indoor ozone removal by PRM under the influence of typical factors
Authors: Jing Lijun , Wang Jun
Published: August 2022

Ozone exposure has been proven to be strongly associated with both morbidity and mortality. In addition, the reaction of ozone with human skin sebum, building materials and indoor other compounds can cause secondary pollution of indoor environment. Therefore, how to effectively control indoor ozone pollution and its induced secondary pollution is an important scientific problem that needs to be solved in the field of indoor air quality. PRM (passive removal materials) can passively remove indoor ozone without energy consumption. According to the mechanism of ozone removal on PRM surface, the effects of material area, reaction probability, transport-limited deposition velocity, outdoor ozone concentration, air change rate (ACH) and indoor reaction rate on ozone removal rate of PRM were analyzed in this study. The results show that the ozone removal rate of PRM is greatly influenced by the reaction probability, the ACH, the surface area and the transport-limited deposition velocity, while the indoor reaction rate and outdoor ozone concentration have no obvious influence. Therefore, in order to remove more indoor ozone by PRM, the position and area of PRM with different reaction probabilities should be chosen reasonably.
Measurement and prediction of breakthrough curve of low-concentration toluene adsorbed by activated carbon
Authors: Sheng Ying , Dong Qingqing , Ren Qiang , Wang Mingyang
Published: August 2022

People spend most of their time indoors. The volatile organic compounds (VOCs) in indoor air represented by toluene inevitably affect people's health. Activated carbon can effectively reduce indoor VOCs pollution. The experiments in the previous studies were carried out at the concentration of tens or hundreds of ppm, which could not reflect the actual adsorption performance of activated carbon in the actual conditions. In this study, a method was proposed to predict breakthrough curve of toluene at ~1 ppm. The method was based on Wheeler-Jonas model, the equilibrium adsorption capacity was predicted by the Freundlich equation, and the adsorption rate constant was obtained by Yoon-Nelson equation. The predicted breakthrough curves were in good agreement with the experimental data in the range of 0.5~4.0 ppm. The adsorption rate constant was predicted using the relationship with inlet concentration of toluene. When the breakout fraction was 20-85%, the relative deviation was 5.54% and 4.08% at 0.5 and 1.0 ppm. This method can predict the adsorption performance and service life of activated carbon for toluene at ppb~ppm level.
Static pressure reset control strategy for roof fans in centralized cooking exhaust systems
Authors: Yu Yanlei , Gao Jun
Published: August 2022

Excessive static pressure and inadequate flow rate at each terminal of the centralized cooking exhaust systems contribute to poor indoor air quality in kitchens. Roof fans can improve the ventilation performance of centralized cooking exhaust system, but the optimal control strategy for roof fans is currently unavailable. This paper proposes a static pressure reset control strategy for variable frequency operation of roof fans that follows the law of normal distribution of simultaneous operating rate. The effect of the roof fan on the static pressure and flow rate distribution in a centralized cooking exhaust system with multiple power sources of range hoods is investigated. The relationship between simultaneous cooking rate and the appropriate set point of the roof fan is determined using experimental and simulation methods. The results show that the proposed static pressure reset control strategy for roof fans has improved control performance and significant potential for energy savings.
Endoscopic ultrasound-guided fine-needle biopsy with or without macroscopic on-site evaluation: a randomized controlled noninferiority trial
Authors: Mangiavillano Benedetto , Crinò Stefano Francesco , Facciorusso Antonio , Di Matteo Francesco , Barbera Carmelo , Larghi Alberto , Rizzatti Gianenrico , Carrara Silvia , Spadaccini Marco , Auriemma Francesco , Fabbri Carlo , Binda Cecilia , Coluccio Chiara , Marocchi Gianmarco , Staiano Teresa , Conti Bellocchi Maria Cristina , Bernardoni Laura , Eusebi Leonardo Henri , Cirota Giovanna Grazia , De Nucci Germana , Stigliano Serena , Manes Gianpiero , Bonanno Giacomo , Ofosu Andrew , Lamonaca Laura , Paduano Danilo , Spatola Federica , Repici Alessandro
Published: August 2022

Background The advantage of using the macroscopic on-site evaluation (MOSE) technique during endoscopic ultrasound-guided fine-needle biopsy (EUS-FNB) performed with 22G Franseen needles has not been investigated. We aimed to compare EUS-FNB with MOSE vs. EUS-FNB performed with three needle passes.

Methods This randomized trial involved 10 Italian referral centers. Consecutive patients referred for EUS-FNB of pancreatic or nonpancreatic solid lesions were included in the study and randomized to the two groups. MOSE was performed by gross visualization of the collected material by the endoscopists and considered adequate when a white/yellowish aggregate core longer than 10 mm was retrieved. The primary outcome was diagnostic accuracy. Secondary outcomes were specimen adequacy, number of needle passes, and safety.

Results 370 patients with 234 pancreatic lesions (63.2 %) and 136 nonpancreatic lesions (36.8 %) were randomized (190 EUS-FNB with MOSE and 180 with standard EUS-FNB). No statistically significant differences were found between EUS-FNB with MOSE and conventional EUS-FNB in terms of diagnostic accuracy (90.0 % [95 %CI 84.8 %–93.9 %] vs. 87.8 % [95 %CI 82.1 %–92.2 %]; P = 0.49), sample adequacy (93.1 % [95 %CI 88.6 %–96.3 %] vs. 95.5 % [95 %CI 91.4 %–98 %]; P = 0.31), and rate of adverse events (2.6 % vs. 1.1 %; P = 0.28). The median number of passes was significantly lower in the EUS-FNB with MOSE group (1 vs. 3; P < 0.001).

Conclusions The accuracy of EUS-FNB with MOSE is noninferior to that of EUS-FNB with three needle passes. MOSE reliably assesses sample adequacy and reduces the number of needle passes required to obtain the diagnosis with a 22G Franseen needle.
Improving Asthma Care Documentation with a Digital Tool–Experience in a Pediatric Institution
Authors: de Groot Stormie , Lawrence Joanna , Liddle James , Campbell Janice , Cheng Daryl R.
Published: August 2022

Background Asthma affects approximately 10% of Australian children. Electronic medical record (EMR) systems and clinical decision support initiatives have been shown to improve the delivery of asthma care. Our institution implemented an EMR-based asthma “hub,” which collates asthma-related information to a central location within a patient's record, provides a template to collect relevant clinical information, allows clinicians to evaluate a patient's history and presentation in a systematic manner and prompts relevant actions.

Objective The aim of the study is to measure year-on-year improvement in asthma-related documentation and provide a key gold-standard aspects of asthma management after the introduction of an EMR asthma “hub” tool in the outpatient setting.

Methods The asthma “hub” was introduced in November 2020. A chart review was conducted of all patients who attended the Complex Asthma Clinic between January-April 2020 and January-April 2021. The provision and presence of documentation of core aspects of asthma care were described in percentages and comparisons of pre- and post-introduction of the asthma “hub” were assessed.

Results There was a significant increase in the documentation of asthma triggers, including smoking/smoker exposure, (47.5–92.6%, p <0.001), current asthma action plans (70.4–86.3%, p = 0.02), and severity scores (46.3–81%, p <0.001) post the introduction of the asthma “hub.” There was no significant difference in documentation of reliever (as required) or regular preventer medications.

Conclusion An evidence-based EMR intervention improved the documentation and provision of aspects of asthma care in an outpatient clinic setting at a tertiary pediatric hospital, suggesting replication in the inpatient and emergency settings would be worthwhile. Further research is required to understand the tool's impact on clinical outcomes and on clinical efficiency and workflow.
Back to the Basics: Inferior Vena Cava Filters
Authors: Covello Brian , Radvany Martin
Published: August 2022

Inferior vena cava filters are an important therapeutic option for patients with venous thromboembolism and contraindication to anticoagulation. Indications for filter placement have varied over the previous decades. This article discusses the history of inferior vena cava filter use, with a basic overview of technology and specific devices. Finally, this article reviews emerging filter design and technology. Understanding the basics of inferior vena cava filters is critical to building more robust clinical data for the purpose of improving patient outcomes.
Subclavian Effort Thrombosis: Pathophysiology, Diagnosis, and Management
Authors: Schwenke Matthew , Goldman Roger E. , Sarkeshik Amir A. , King Eric C.
Published: August 2022

Subclavian vein (SCV) effort thrombosis, also known as Paget-Schroetter syndrome or venous thoracic outlet syndrome, is an uncommon condition that affects individuals with an irregularly narrow thoracic outlet who engage in repetitive overhead motions of the affected arm. Venous injury arises from microtraumas that occur from the repetitive compression of the SCV between the first rib and the overlying clavicle. Additional sources of extrinsic compression can be due to the anterior scalene muscle, subclavius muscle, and costoclavicular ligament. SCV effort thrombosis is a distinct entity from other forms of deep venous thrombosis and requires unique diagnostic and treatment considerations. Early catheter-directed therapy in the form of pharmacomechanical or catheter-directed thrombolysis combined with prompt surgical thoracic outlet decompression offers patients the best chances for early and durable symptom relief.
The Effect of Neuromodulatory Drugs on the Intensity of Chronic Pelvic Pain in Women: A Systematic Review
Authors: Andrade Marcela Almeida , Soares Leila Cristina , Oliveira Marco Aurélio Pinho de
Published: August 2022

Objective: To evaluate the effect of neuromodulatory drugs on the intensity of chronic pelvic pain (CPP) in women.

Data sources: Searches were carried out in the PubMed, Cochrane Central, Embase, Lilacs, OpenGrey, and Clinical Trials databases.

Selection of studies: The searches were carried out by two of the authors, not delimiting publication date or original language. The following descriptors were used: chronic pelvic pain in women OR endometriosis, associated with MESH/ENTREE/DeCS: gabapentinoids, gabapentin, amitriptyline, antidepressant, pregabalin, anticonvulsant, sertraline, duloxetine, nortriptyline, citalopram, imipramine, venlafaxine, neuromodulation drugs, acyclic pelvic pain, serotonin, noradrenaline reuptake inhibitors, and tricyclic antidepressants, with the Boolean operator OR. Case reports and systematic reviews were excluded.

Data collection: The following data were extracted: author, year of publication, setting, type of study, sample size, intervention details, follow-up time, and results.

Data synthesis: A total of 218 articles were found, with 79 being excluded because they were repeated, leaving 139 articles for analysis: 90 were excluded in the analysis of the titles, 37 after reading the abstract, and 4 after reading the articles in full, and 1 could not be found, therefore, leaving 7 articles that were included in the review.

Conclusion: Most of the studies analyzed have shown pain improvement with the help of neuromodulators for chronic pain. However, no improvement was found in the study with the highest statistical power. There is still not enough evidence that neuromodulatory drugs reduce the intensity of pain in women with CPP.
Coincidence Analysis: A Novel Approach to Modeling Nurses' Workplace Experience
Authors: Womack Dana M. , Miech Edward J. , Fox Nicholas J. , Silvey Linus C. , Somerville Anna M. , Eldredge Deborah H. , Steege Linsey M.
Published: August 2022

Objectives The purpose of this study is to identify combinations of workplace conditions that uniquely differentiate high, medium, and low registered nurse (RN) ratings of appropriateness of patient assignment during daytime intensive care unit (ICU) work shifts.

Methods A collective case study design and coincidence analysis were employed to identify combinations of workplace conditions that link directly to high, medium, and low RN perception of appropriateness of patient assignment at a mid-shift time point. RN members of the study team hypothesized a set of 55 workplace conditions as potential difference makers through the application of theoretical and empirical knowledge. Conditions were derived from data exported from electronic systems commonly used in nursing care.

Results Analysis of 64 cases (25 high, 24 medium, and 15 low) produced three models, one for each level of the outcome. Each model contained multiple pathways to the same outcome. The model for “high” appropriateness was the simplest model with two paths to the outcome and a shared condition across pathways. The first path comprised of the absence of overtime and a before-noon patient discharge or transfer, and the second path comprised of the absence of overtime and RN assignment to a single ICU patient.

Conclusion Specific combinations of workplace conditions uniquely distinguish RN perception of appropriateness of patient assignment at a mid-shift time point, and these difference-making conditions provide a foundation for enhanced observability of nurses' work experience during hospital work shifts. This study illuminates the complexity of assessing nursing work system status by revealing that multiple paths, comprised of multiple conditions, can lead to the same outcome. Operational decision support tools may best reflect the complex adaptive nature of the work systems they intend to support by utilizing methods that accommodate both causal complexity and equifinality.
Redirecting an asteroid with introductory mechanics
Authors: Piccone Ashley
Published: August 2022

NASA and ESA’s Double Asteroid Redirection Test makes a lively, contemporary topic for learning basic physics.
Random regression models for multi-environment, multi-time data from crop breeding selection trials
Authors: De Faveri J. , Verbyla A. P. , Rebetzke G.
Published: August 2022

Context In order to identify best crop genotypes for recommendation to breeders, and ultimately for use in breeding, evaluation is usually conducted in field trials across a range of environments, known as multi-environment trials. Increasingly, many breeding traits are measured over time, for example with high-throughput phenotyping at different growth stages in annual crops or repeated harvests in perennial crops. Aims This study aims to provide an efficient, accurate approach for modelling genotype response over time and across environments, accounting for non-genetic sources of variation such as spatial and temporal correlation. Methods Because the aim is genotype selection, genetic effects are fitted as random effects, and so the approach is based on random regression, in which linear or non-linear models are used to model genotype responses. A method for fitting random regression is outlined in a multi-environment situation, using underlying cubic smoothing splines to model the mean trend over time. This approach is illustrated on six wheat experiments, using data on grain-filling over thermal time. Key results The method correlates genetic effects over time and environments, providing predicted genotype responses while incorporating spatial and temporal correlation between observations. Conclusions The approach provides robust genotype predictions by accounting for temporal and spatial effects simultaneously under various situations including those in which trials have different measurement times or where genotypes within trials are not measured at the same times. The approach facilitates investigation into genotype by environment interaction (G × E) both within and across environments. Implications The models presented have potential to increase accuracy of predictions over measurement times and trials, provide predictions at times other than those observed, and give a greater understanding of G × E interaction, hence improving genotype selection across environments for repeated-measures traits.
Why patients attend after-hours medical services: a cross-sectional survey of patients across the Australian Capital Territory
Authors: Barnes Katelyn , Ceramidas Dagmar , Douglas Kirsty
Published: August 2022

Background Almost half of Australian after-hours emergency department (ED) presentations are rated as ‘non-urgent’ by clinicians and are suggested to be managed by community-based services, such as general practice (GP). This paper reports patient reasons for presenting for medical care after hours, and reasons for selection of specific services across a health system. Methods A cross-sectional survey was conducted across the Australian Capital Territory. Patients voluntarily completed questionnaires in waiting rooms during the after-hours periods of one weekday and one weekend in 2019 at 28/51 extended hours GPs, 3/3 medical deputising services (MDS), 3/3 nurse-led walk-in-clinics (WICs), and 2/2 public emergency departments (EDs). Results Of 3371 presentations, 1992 patients completed a survey, with 58% from GPs (n = 1149), 16% from WIC (n = 317), 10% from MDS (n = 193), and 17% from EDs (n = 333). Most patients presented with self-rated new issues (n = 987, 49.5%) and were uncertain of the urgency of their issues (n = 723, 36.7%). Common reasons for presenting to WIC, MDS, and EDs included the problem occurring after hours, and patients concern about the issue. Common reasons for presenting to GP were related to personal preference for after-hours care. Conclusions Patients present to after-hours medical services for both perceived need and convenience. Most patients appear to be self-selecting after-hours services appropriately aligned with advertised services; except for GP patients who were attending after hours for care that is often non-urgent and could be seen in usual working hours. This study should be replicated to account for local health systems, and coronavirus disease 2019 (COVID-19)-related changes to health care.
Ultrasound and surface electromyography analyses reveal an intensity dependent active stretch‐shortening cycle of the vastus lateralis muscle during ergometer rowing
Authors: Held Steffen , Raiteri Brent , Rappelt Ludwig , Hahn Daniel , Donath Lars
Published: August 2022

A rowing cycle is characterised by a stretch‐shortening cycle (SSC) at the quadriceps femoris muscle‐tendon unit (MTU) level. However, due to the associated decoupling between MTU and muscle fascicle length changes, it remains unclear whether a rowing cycle causes active stretch at the muscle level. Fifteen young, sub‐elite, male rowers (19.5 ± 1.6 yr; 1.94 ± 0.06 m; 91.9 ± 5.4 kg; rowing experience: 7.5 ± 2.8 yr) performed randomised 60‐s rowing intervals using a traditional style at a low (LiR) and high intensity (HiR) and a micro‐pause style at a low intensity (MpR). Muscle activity, knee joint angles, and muscle fascicle length changes from the left‐sided vastus lateralis (VL) muscle were quantified using surface electromyography, inertial measurement units, and B‐mode ultrasound imaging, respectively. All rowing conditions showed active fascicle stretch during late knee flexion (p≤0.001, standardised mean difference (SMD) ≥0.72) and subsequent active fascicle shortening throughout knee extension. Active fascicle stretch duration, amplitude and velocity (rANOVA: p≤0.001, ηp2 = 0.49) were not significantly different (p≥0.174; SMD≤0.26) between LiR and MpR, but were significantly increased during HiR (p≤0.001; SMD≥0.70). The percentage of rowing cycles that involved active fascicle stretch (rANOVA: p≤0.001, ηp2 = 0.95; post‐hoc: p≤0.001, SMD≥0.87) was also significantly higher for HiR (98.3 ±12.9%) compared with both LiR (65.0 ± 48.1%) and MpR (68.3 ± 46.9%). In conclusion, rowing involves SSC at the VL muscle fascicle level, but the amount of active stretch differs between rowing intensities, with the longest, largest, and fastest active stretch occurring during HiR. SSC‐based mechanisms may therefore contribute more to rowing performance during HiR than LiR or MpR.
Knudsen force based double beam MEMS vacuum pressure sensor
Authors: Kannan Sivasundari , Bhattacharya Enakshi
Published: August 2022

Knudsen forces are gas molecular forces, generated due to the presence of a thermal gradient between two surfaces in rarefied gas and can be effectively used for the measurement of low pressures. This work reports on a Knudsen force based micro electro mechanical systems low pressure sensor consisting of two stacked beams of polysilicon—one acting as a heater while the other as a sensor. The structure is fabricated using a double sacrificial layer surface micromachining process. The thermal gradient across the two stacked beams is induced by resistive heating of the heater beam. The effect of using two separate beams for heating and sensing has been investigated at different heater current and the results are compared with the existing works. The provision of two beams has resulted in the sensor functioning at very low pressure of less than 0.1 Pa with an improved sensitivity of 15.5 fF mPa−1.
Glassy disorder-induced effects in noisy dynamics of Bose–Hubbard and Fermi–Hubbard systems
Authors: Sarkar Saubhik , Sen Ujjwal
Published: August 2022

We address the effects of quenched disorder averaging in the time-evolution of systems of ultracold atoms in optical lattices in the presence of noise, imposed by an environment. For bosonic systems governed by the Bose–Hubbard Hamiltonian, we quantify the response of disorder in Hamiltonian parameters in terms of physical observables, including bipartite entanglement in the ground state, and report the existence of disorder-induced enhancement in weakly interacting cases. For systems of two-species fermions described by the Fermi–Hubbard Hamiltonian, we find similar results. In both cases, our dynamical calculations show no appreciable change in the effects of disorder from that of the initial state of the evolution. We explain our findings in terms of the statistics of the disorder in the parameters and the behaviour of the observables with the parameters.
A compact terahertz frequency selective surface with fast roll-off characteristics
Authors: Ruan Jiu Fu , Tao Zhi , Zou Rui Zhi , Meng Zi Fan , Pan Sheng Min
Published: August 2022

A simple and compact terahertz frequency selective surface (FSS) with high selectivity is presented for cases of normal incidence. Guidelines for the design along with the operation mechanism are presented in detail from the view of an equivalent circuit. The design is implemented by mapping the lumped components of a microwave filter topology circuit with two transmission zeros to structures of the FSS; the mapping is realized by slotting a cross-shaped aperture in the grid. An intensive study on the equivalent circuit model predicts the existence of transmission zeros and poles. It can afford two transmission zeros and two transmission poles ranging from 350 GHz to 450 GHz with a band separation of 1.05 and 1.07, thereby exhibiting fast roll-off characteristics. The two transmission zeros can be controlled independently by simply changing the structure parameters of the unit cell. The proposed FSS is superior in terms of roll-off rate as well as the balance between selectivity and overall thickness. The measured results of the prototype are consistent with the simulation results, which validates the robustness of the design.
Impact of dynamic stretching exponent on the correlation between liquid fragility and nonexponentiality at the glass transition
Authors: Doss Karan , Mauro John C
Published: August 2022

The presence of large scatter in linear response data has cast doubt on the existence of an inverse correlation between liquid fragility and nonexponentiality, as originally proposed by Böhmer et al (1993 J. Chem. Phys.
99 4201). We present a model for the temperature dependence of the stretching exponent based on the Mauro–Yue–Ellison–Gupta–Allan model for supercooled liquid viscosity and discuss the factors impacting the relationship between fragility and the stretching exponent at the glass transition. The proposed model exhibits distinct advantages over previous models in terms of interpretability and limit behaviors for the temperature dependence.
Living in a non-flat universe: theoretical formalism
Authors: Baumgartner Sandra , Yoo Jaiyul
Published: August 2022

Recent analysis of the Planck measurements opened a possibility that we live in a non-flat universe. Given the renewed interest in non-zero spatial curvature, here we re-visit the light propagation in a non-flat universe and provide the gauge-invariant expressions for the cosmological probes: the luminosity distance, galaxy clustering, weak gravitational lensing, and cosmic microwave background anisotropies. With the positional dependence of the spatial metric, the light propagation in a non-flat universe is much more complicated than in a flat universe. Accounting for all the relativistic effects and including the vector and tensor contributions, we derive the expressions for the cosmological probes and explicitly verify their gauge invariance. We compare our results to previous work in a non-flat universe, if present, but this work represents the first comprehensive investigation of the cosmological probes in a non-flat universe. Our theoretical formalism in a non-flat universe will play a crucial role in constraining the spatial curvature in the upcoming large-scale surveys.
Quantum diffusion in sharp transition to non-slow-roll phase
Authors: Ahmadi Nahid , Noorbala Mahdiyar , Feyzabadi Niloufar , Eghbalpoor Fatemeh , Ahmadi Zahra
Published: August 2022

Transitions between different inflationary slow-roll scenarios are known to provide short
non-slow-roll periods with non-trivial consequences. We consider the effect of quantum diffusion
on the inflationary dynamics in a transition process. Using the stochastic δ𝒩 
formalism, we follow the detailed evolution of noises through a sharp transition modeled by the
Starobinsky potential, although some of our results apply to any sharp transition. We find how
the stochastic noise induced by the transition affects the coarse-grained fields. We then
consider the special case that the potential is flat after the transition. It is found that,
during a particular phase of evolution, the noise we obtain cannot drive the inflaton past the
classically unreachable field values; so the boundary crossing is delayed. By deriving the
characteristic function, we also study the tail behavior for the distribution of curvature
perturbations ζ, which we find to decay faster than exp(-3ζ).
B-L genesis by sliding inflaton
Authors: Yoshimura M.
Published: August 2022

We propose a new mechanism of lepton (L) number asymmetry generation,
hence offer an explanation of matter-antimatter imbalance when
a significant amount of baryon number is later
transformed from this L-number by known electroweak sphaleron mediated process.
The basic theoretical framework is a
recently proposed multiple scalar-tensor gravity that dynamically solves
the cosmological constant problem.
The L-asymmetry generation in one of two proposed scenarios
is triggered by dynamical relaxation of scalar inflaton field towards
the zero cosmological constant.
CPT violation (C = charge conjugation, P = parity operation,
T = time reversal) in the presence of a chemical potential
gives the necessary time arrow, and
lepton number violating scattering in cosmic thermal medium
generates a net cosmological L-number via resonance formation.
Another scenario is L-asymmetry generation from
evaporating primordial black holes.
These proposed mechanisms do not require CP violating phases
in physics beyond the standard model:
the new required physics
is existence of heavy Majorana leptons of masses 1015 ∼ 1017 GeV
that realizes the seesaw mechanism.
We identify the cosmological epoch of lepto-genesis in two scenarios,
which may give the right amount of observed baryon to entropy ratio.
It might even be possible to experimentally determine microscopic physics parameter,
masses of three heavy Majorana leptons
by observing astrophysical footprints of primordial black hole evaporation
at specified hole masses.
Inflationary epoch in the presence of holographic dark energy
Authors: Delgado Paola C. M. , Ganz Alexander , Lin Chunshan
Published: August 2022

We analyze the effects of the holographic dark energy model in a single field slow-roll inflation, taking into account both the holographic and the dark radiation components. In particular, we obtain the background evolution and compute the scalar and tensor power spectra. For the scalar sector we show that the power spectrum of the curvature perturbation encompasses the standard single field result and a correction proportional to Ωhde/ϵ, where Ωhde is the fractional density of the holographic component and ϵ is the first slow-roll parameter. This correction might be of order unity in the very beginning of the inflationary phase and decays rapidly. For the primordial gravitational waves we find the spectral index receives a correction from the graviton mass term, which decays in the first inflationary e-folds.
Pixel size limit of the PRIMA implants: from humans to rodents and back
Authors: Wang Bing-Yi , Chen Zhijie Charles , Bhuckory Mohajeet , Kochnev Goldstein Anna , Palanker Daniel
Published: August 2022

Objective. Retinal prostheses aim at restoring sight in patients with retinal degeneration by electrically stimulating the inner retinal neurons. Clinical trials with patients blinded by atrophic age-related macular degeneration using the PRIMA subretinal implant, a 2 × 2 mm array of 100 µm-wide photovoltaic pixels, have demonstrated a prosthetic visual acuity closely matching the pixel size. Further improvement in resolution requires smaller pixels, which, with the current bipolar design, necessitates more intense stimulation. Approach. We examine the lower limit of the pixel size for PRIMA implants by modeling the electric field, leveraging the clinical benchmarks, and using animal data to assess the stimulation strength and contrast of various patterns. Visually evoked potentials measured in Royal College of Surgeons rats with photovoltaic implants composed of 100 µm and 75 µm pixels were compared to clinical thresholds with 100 µm pixels. Electrical stimulation model calibrated by the clinical and rodent data was used to predict the performance of the implant with smaller pixels. Main results. PRIMA implants with 75 µm bipolar pixels under the maximum safe near-infrared (880 nm) illumination of 8 mW mm−2 with 30% duty cycle (10 ms pulses at 30 Hz) should provide a similar perceptual brightness as with 100 µm pixels under 3 mW mm−2 irradiance, used in the current clinical trials. Contrast of the Landolt C pattern scaled down to 75 µm pixels is also similar under such illumination to that with 100 µm pixels, increasing the maximum acuity from 20/420 to 20/315. Significance. Computational modeling defines the minimum pixel size of the PRIMA implants as 75 µm. Increasing the implant width from 2 to 3 mm and reducing the pixel size from 100 to 75 µm will nearly quadrupole the number of pixels, which should be very beneficial for patients. Smaller pixels of the same bipolar flat geometry would require excessively intense illumination, and therefore a different pixel design should be considered for further improvement in resolution.
Zero-field level-crossing resonances in a small low-temperature cesium vapor cell for atomic magnetometry applications
Authors: Brazhnikov D V , Vishnyakov V I , Andreeva C , Goncharov A N
Published: August 2022

Zero-field level-crossing resonances (LCRs) underlay one of the most robust and simplest techniques in atomic magnetometry. LCR-based miniaturized magnetic field sensors have already found relevant applications in biology and medicine. Such sensors utilize a single circularly polarized light wave to interact with alkali-metal atoms (usually Rb or Cs) and to observe the LCR in a vapor-cell transmission when a transverse magnetic field is scanned around zero value. A high-temperature regime (T ≈ 120 − 160°C) is required to achieve a desirable sensitivity of measurements. It can be a problem for some applications, especially in a multi-channel mode of operation. Here, we consider two spectroscopy techniques that can provide high-contrast and narrow LCRs under a relatively low temperature of the cell (≤60°C). These techniques imply using two light waves: the pump wave to polarize the atoms and the probe one to register the resonance. A cubic glass cell of 5×5×5 mm3 size is used in the experiments. It is filled with cesium vapors and neon as a buffer gas. The results can be used for developing a miniaturized low-power high-sensitivity magnetic field sensor for biomedical applications.
Investigation of the dependence of the reflection coefficient on the modulation parameters and defects of the fiber Bragg gratings
Authors: Stankevich K M , Butkovskiy O Y , Kochuev D A , Chernikov A S , Privodnov I I
Published: August 2022

In this article we studied a model of changes in the amplitude of the spectral density maxima and interference of the side lobes of backscattering radiation from Fiber Bragg gratings (FBGs). For this purpose a computer simulation of the matrix system of equations of coupled modes depending on the modulation depth and wavelength was carried out. The practical significance of the work lies in finding the laws of dependence of the level of oscillation on changes in the input parameters to obtain the greatest efficiency of optical fiber containing fiber Bragg gratings. An attempt is made to model technological defects and their influence on the character of FBG backscattering.
Synthesis of copper nanoparticles by laser ablation
Authors: Antipov A A , Putilov A G , Osipov A V , Shepelev A E , Glebov V N , Maliutin A M
Published: August 2022

The synthesis of copper nanoparticles using a pulsed alexandrite laser is demonstrated. The laser operated in a free generation mode with a pulse duration of about 250 μs. The copper target was placed in distilled water and glycerin. The obtained colloidal solutions were investigated by dynamic light scattering, and the deposited structures were studied by atomic force and electron microscopy. The concentration of nanoparticles depended on the power of the laser radiation, the scanning speed and the exposure time. The smallest particles size was obtained at a frequency of 5 Hz at a wavelength of 750 nm. Colloids obtained in distilled water contain copper nanoparticles, which oxidize over time.
Laser synthesis of plasmonic gold nanoparticles
Authors: Veiko V P , Morozova A A , Lutoshina D S , Shchedrina N N , Nguyen T A , Lonshakova M V , Sergeev M M , Odintsova G V
Published: August 2022

This work investigates the results of the laser irradiation synthesis of nanoparticles on the gold surface. The sizes and chemical composition of produced nanoparticles were determined, the possibility of changing the colorimetric characteristics of the gold surface was shown.
Er3+ doped sesquioxide Y2O3 optical ceramics: synthesis and spectral-luminescent properties
Authors: Balashov V , Chkalov R , Fedin A , Gerke M , Gorbachenya K , Kisel’ V , Kochuev D , Kozlova S , Kuleshov N , Lopukhin K
Published: August 2022

In this conribution we describe the technological process of transparent Er3+:Y2O3 ceramic synthesis, a prospective medium for future laser applications. Hot isostatic pressing (HIP) was used to improve the optical quality of the final product. As the results of our efforts the material with an optical transmission of 0.78-0.80 was obtained, that is close to the theoretical maximum value of 0.83. The main spectral and luminescent properties of the created Er3+:Y2O3 optical ceramics in the spectral range of 1.4-1.65 microns was determined and is reported in this work.