Volume Of Space Research Articles

Evaluating high-resolution computed tomography derived 3-D joint space metrics of the metacarpophalangeal joints between rheumatoid arthritis and age- and sex-matched control participants

IntroductionRheumatoid arthritis (RA) is commonly characterized by joint space narrowing. High-resolution peripheral quantitative computed tomography (HR-pQCT) provides unparalleled in vivo visualization and quantification of joint space in extremity joints commonly affected by RA, such as the 2nd and 3rd metacarpophalangeal joints. However, age, sex, and obesity can also influence joint space narrowing. Thus, this study aimed to determine whether HR-pQCT joint space metrics could distinguish between RA patients and controls, and determine the effects of age, sex and body mass index (BMI) on these joint space metrics.MethodsHR-pQCT joint space metrics (volume, width, standard deviation of width, maximum/minimum width, and asymmetry) were acquired from RA patients and age-and sex-matched healthy control participants 2nd and 3rd MCP joints. Joint health and functionality were assessed with ultrasound (i.e., effusion and inflammation), hand function tests, and questionnaires.ResultsHR-pQCT-derived 3D joint space metrics were not significantly different between RA and control groups (p > 0.05), despite significant differences in inflammation and joint function (p < 0.05). Joint space volume, mean joint space width (JSW), maximum JSW, minimum JSW were larger in males than females (p < 0.05), while maximum JSW decreased with age. No significant association between joint space metrics and BMI were found.ConclusionHR-pQCT did not detect group level differences between RA and age-and sex-matched controls. Further research is necessary to determine whether this is due to a true lack of group level differences due to well-controlled RA, or the inability of HR-pQCT to detect a difference.

Landscape Design and Green Space Perception Enhancement Based on Panoramic Imaging and Segnet

Green view rate is an intuitive evaluation criterion used for green space perception. Traditional research on green view rate is mostly calculated based on flat images, which cannot fully reflect the subjective human perception of green volume in three-dimensional space. Based on the panoramic image, we propose the concept of panoramic green perception rate, obtain spherical panoramic photos by panoramic camera, convert isometric cylindrical projection into isoprojective cylindrical projection, and use the convolutional neural network model based on semantic segmentation to automatically identify the area of vegetation to achieve automatic recognition and measurement of panoramic green perception rate. The results were compared with manual discrimination and showed that the average intersection ratio (mIoU) of greenery recognition using Dilated ResNet-105 was 62.53%, and the average difference with manual recognition was 9.17%.

Optimizations of structure stiffnesses and sensitivities of Y-type six-axis force/torque sensor

Purpose The six-axis force/torque sensor based on a Y-type structure has the advantages of simple structure, small space volume, low cost and wide application prospects. To meet the overall structural stiffness requirements and sensor performance requirements in robot engineering applications, this paper aims to propose a Y-type six-axis force/torque sensor. Design/methodology/approach The performance indicators such as each component sensitivities and stiffnesses of the sensor were selected as optimization objectives. The multiobjective optimization equations were established. A multiple quadratic response surface in ANSYS Workbench was modeled by using the central composite design experimental method. The optimal manufacturing structural parameters were obtained by using multiobjective genetic algorithm. Findings The sensor was optimized and the simulation results show that the overload resistance of the sensor is 200%F.S., and the axial stiffness, radial stiffness, bending stiffness and torsional stiffness are 14.981 kN/mm, 16.855 kN/mm, 2.0939 kN m/rad and 6.4432 kN m/rad, respectively, which meet the design requirements, and the sensitivities of each component of the optimized sensor have been well increased to be 2.969, 2.762, 4.010, 2.762, 2.653 and 2.760 times as those of the sensor with initial structural parameters. The sensor prototype with optimized parameters was produced. According to the calibration experiment of the sensor, the maximum Class I and II errors and measurement uncertainty of each force/torque component of the sensor are 1.835%F.S., 1.018%F.S. and 1.606%F.S., respectively. All of them are below the required 2%F.S. Originality/value Hence, the conclusion can be drawn that the sensor has excellent comprehensive performance and meets the expected practical engineering requirements.

Delay Painlevé-I equation, associated polynomials and Masur-Veech volumes

We study a delay-differential analogue of the first Painlevé equation obtained as a delay periodic reduction of Shabat's dressing chain. We construct formal entire solutions to this equation and introduce a new family of polynomials (called Bernoulli-Catalan polynomials), which are defined by a nonlinear recurrence of Catalan type, and which share properties with Bernoulli and Euler polynomials. We also discuss meromorphic solutions and describe the singularity structure of this delay Painlevé-I equation in terms of an affine Weyl group of type A1(1). As an application we demonstrate the link with the problem of calculation of the Masur-Veech volumes of the moduli spaces of meromorphic quadratic differentials by re-deriving some of the known formulas.

Construction of Adaptive Deformation Block: Rational Molecular Editing of the N-Rich Host Molecule to Remove Water from the Energetic Hydrogen-Bonded Organic Frameworks.

Energetic hydrogen-bonded organic frameworks (E-HOFs), as a type of energetic material, spark fresh vitality to the creation of high energy density materials (HEDMs). However, E-HOFs containing cations and anions face challenges such as reduced energy density due to the inclusion of crystal water. In this work, the modification of amino groups in N-rich organic units could form a smart building block of hydrogen-bonded frameworks capable of changing the volume of the void space in the molecule through adaptive deformation of E-MOF blocks, thus enabling the replacement of water. Based on the above strategy, we report an interesting example of a series of hydrogen-bonded organic frameworks (E-HOF 2a and 3a) synthesized using a facile method. The crystal structure data of all of the compounds were also obtained in this work. Anhydrous 2a and 3a exhibit higher density, good thermal stability, and low mechanical sensitivity. The strategy of covalent bond modification for the host molecules of energetic frameworks shows enormous potential in eliminating the crystalline H2O of hydration and exploring high energy density materials.

Indoor view-based visibility analysis using UAV and TLS point clouds with Line-of-Sight correction

Visibility analysis is a crucial geographic information processing method, used to assess the observable spatial range from a particular location under specific conditions. It has broad applications, such as urban planning, landscape design and environmental research. Laser scanning provides detailed and accurate 3D data for visibility analysis, called point cloud. However, certain deficiencies still exist in current point cloud-based visibility analysis methods. Few methods are developed from indoor perspective and the influence of point cloud void is rarely considered. Firstly, indoor viewpoints are generated based on the windows extracted from terrestrial laser scanning (TLS) point cloud and unmanned aerial vehicle (UAV) point cloud is used to provide 3D representation of the environment around the viewpoint. Then, a half-sphere viewshed is created for each indoor viewpoint to analyze the visible spatial range. In this step, a novel line-of-sight correction method is proposed based on the semantic information from UAV point cloud, to correct the biased observation distance resulted from point cloud voids. Lastly, the volume of visible space is calculated based on the corrected viewshed image, to evaluate the visibility of each indoor viewpoint. Our method is validated on two datasets. The results indicate that our method enables more accurate simulation of visible space compared with previous studies by considering the effect of point cloud void. The proposed method can support the urban design from the perspective of indoor visual perception and accurate calculation of other visual factors in visual quality evaluation.

Trabecular bone variation in the gorilla calcaneus.

Calcaneal external shape differs among nonhuman primates relative to locomotion. Such relationships between whole-bone calcaneal trabecular structure and locomotion, however, have yet to be studied. Here we analyze calcaneal trabecular architecture in Gorilla gorilla gorilla, Gorilla beringei beringei, and G. b. graueri to investigate general trends and fine-grained differences among gorilla taxa relative to locomotion. Calcanei were micro-CT scanned. A three-dimensional geometric morphometric sliding semilandmark analysis was carried out and the final landmark configurations used to position 156 volumes of interest. Trabecular thickness (Tb.Th), trabecular spacing (Tb.Sp), and bone volume fraction (BV/TV) were calculated using the BoneJ plugin for ImageJ and MATLAB. Non-parametric MANOVAs were run to test for significant differences among taxa in parameter raw values and z-scores. Parameter distributions were visualized using color maps and summarized using principal components analysis. There are no significant differences in raw BV/TV or Tb.Th among gorillas, however G. b. beringei significantly differs in z-scores for both parameters (p = <0.0271). All three taxa exhibit relatively lower BV/TV and Tb.Th in the posterior half of the calcaneus. This gradation is exacerbated in G. b. beringei. G. b. graueri significantly differs from other taxa in Tb.Sp z-scores (p < 0.001) indicating a different spacing distribution. Relatively higher Tb.Th and BV/TV in the anterior calcaneus among gorillas likely reflects higher forces associated with body mass (transmitted through the subtalar joint) relative to forces transferred through the posterior calcaneus. The different Tb.Sp pattern in G. b. graueri may reflect proposed differences in foot positioning during locomotion.

Quantification of cervical spinal stenosis by automated 3D MRI segmentation of spinal cord and cerebrospinal fluid space

Abstract Design Prospective diagnostic study. Objectives Anatomical evaluation and graduation of the severity of spinal stenosis is essential in degenerative cervical spine disease. In clinical practice, this is subjectively categorized on cervical MRI lacking an objective and reliable classification. We implemented a fully-automated quantification of spinal canal compromise through 3D T2-weighted MRI segmentation. Setting Medical Center - University of Freiburg, Germany. Methods Evaluation of 202 participants receiving 3D T2-weighted MRI of the cervical spine. Segments C2/3 to C6/7 were analyzed for spinal cord and cerebrospinal fluid space volume through a fully-automated segmentation based on a trained deep convolutional neural network. Spinal canal narrowing was characterized by relative values, across sever segments as adapted Maximal Canal Compromise (aMCC), and within the index segment as adapted Spinal Cord Occupation Ratio (aSCOR). Additionally, all segments were subjectively categorized by three observers as “no”, “relative” or “absolute” stenosis. Computed scores were applied on the subjective categorization. Results 798 (79.0%) segments were subjectively categorized as “no” stenosis, 85 (8.4%) as “relative” stenosis, and 127 (12.6%) as “absolute” stenosis. The calculated scores revealed significant differences between each category (p ≤ 0.001). Youden’s Index analysis of ROC curves revealed optimal cut-offs to distinguish between “no” and “relative” stenosis for aMCC = 1.18 and aSCOR = 36.9%, and between “relative” and “absolute” stenosis for aMCC = 1.54 and aSCOR = 49.3%. Conclusion The presented fully-automated segmentation algorithm provides high diagnostic accuracy and objective classification of cervical spinal stenosis. The calculated cut-offs can be used for convenient radiological quantification of the severity of spinal canal compromise in clinical routine.

Influence of the dead space volume on the working processes and performance of a piston hybrid power machine with two suction valves

Influence of the dead space volume on the working processes and performance of a piston hybrid power machine with two suction valves

Correction: Intersection theory and volumes of moduli spaces of flat metrics on the sphere

Correction: Intersection theory and volumes of moduli spaces of flat metrics on the sphere

Sensitivity volume as figure-of-merit for maximizing data importance in electrical impedance tomography

Objective. Electrical impedance tomography (EIT) is a noninvasive imaging method whereby electrical measurements on the periphery of a heterogeneous conductor are inverted to map its internal conductivity. The EIT method proposed here aims to improve computational speed and noise tolerance by introducing sensitivity volume as a figure-of-merit for comparing EIT measurement protocols. Approach. Each measurement is shown to correspond to a sensitivity vector in model space, such that the set of measurements, in turn, corresponds to a set of vectors that subtend a sensitivity volume in model space. A maximal sensitivity volume identifies the measurement protocol with the greatest sensitivity and greatest mutual orthogonality. A distinguishability criterion is generalized to quantify the increased noise tolerance of high sensitivity measurements. Main result. The sensitivity volume method allows the model space dimension to be minimized to match that of the data space, and the data importance to be increased within an expanded space of measurements defined by an increased number of contacts. Significance. The reduction in model space dimension is shown to increase computational efficiency, accelerating tomographic inversion by several orders of magnitude, while the enhanced sensitivity tolerates higher noise levels up to several orders of magnitude larger than standard methods.

Apartment with Acoustics Environment Approach in Center Jakarta

Environmental acoustics have an important architectural role that has a major influence on the productivity, health and sustainability of cities. living and proximity to the workplace have become essential needs for workers and entrepreneurs in today’s era. As many still work using the hybrid system, where workers require a comfortable living space as well as a comfortable workspace to support productivity, meetings and work can be done in the same place. SOHO apartments provide a solution to this problem, but they are prone to acoustic issues due to their open plan and loft concepts. The large volume of space requires special treatment, especially in terms of reverberation time. Excessive reverberation time can disrupt the productivity of residents and workers. A quiet space is needed to support these activities. This study aims to explain how environmental acoustics can improve the quality of a room and increase productivity and healthy through the application of acoustic absorbent material. However, the use of absorbent material is not very good for the environment if its use is not appropriate, therefore the selection of absorbent material must be analyzed carefully, so that what is obtained is PET (Polyethylene Terephthalate) material which supports all aspects of the SOHO apartment’s space needs and also material recycling up to 90%-99% which is good for sustainability. This study uses a combination method of observation and precedent studies. The results of this research involve the application of parameters to address acoustic issues in SOHO apartments and improve the acoustic quality of the space.

Assessing the Accuracy of Lateral Cephalogram in Quantifying Three-Dimensional Pharyngeal Airway Morphology Compared to Cone-Beam Computed Tomography.

When it comes to orthodontic diagnosis and treatment planning, the structures of the upper and lower airway spaceare crucial because of therole they play in craniofacial development. The major objective of this study was to evaluate the accuracy of lateral cephalogram in the evaluation of upper and lower pharyngeal space by comparing it to clinical usage of cone-beam computed tomography (CBCT) in quantifying the 3D morphology of the pharyngeal airway. In total, 70 patients were included in the study. They had both a CBCT scan and a lateral cephalogram performed within a week of each other. Different cephalometric landmarks have been utilized to estimate linear and area dimensions for use in lateral cephalogram airway investigations. By superimposing the lateral cephalogram measurement of the vertical height of the pharyngeal airwayover axial CBCT slices of 0.8 to 1 mm in thickness, airway volumes were calculated. For this study, we measured the pharyngeal airway space in each patient in two dimensions (2D) using the airway area from the lateral cephalogram and in three dimensions (3D) using the airway volume from the CBCT scan over the same region of interest, using a uniform scale and magnification throughout all split 3D volumes. The mean value of the area of pharyngeal space calculated by lateral cephalograph analysis (LCA) was 336.35 ± 86.49 mm2. The maximum value was 551.234 mm2. The minimum value was 206.32 mm2. The mean value of the volume of the same area calculated using CBCT was 3409.11 ± 1237.96 mm3. The maximum value was 5887.23 mm3. When the area calculated using LCA was compared with the volume calculated using CBCT, the correlation between them was significant statistically(r=0.831, p-value =0.000). The mean values of volume evaluated in 3D CBCT in males were 4198±1008 mm3 while for females it was 2980±1134.5 mm3. During the statistical analysis,these observations were found to have a positive correlation with increased volume of pharyngeal space in males as compared to that of females (p=0.006). The values of the area of pharyngeal space calculated using LCA in males was 370.1±60.9 mm2. while it was 301.9±88 mm2 in females. The area estimated for the pharyngeal airway on LCA correlates strongly with the volume determined by a CBCT scan. Since we have considered pharyngeal space analysis using CBCT to be a reliable and standard methodology, therefore a positive correlation of area calculated using LCA with volume calculated using CBCT shows that the analysis made by LCA can be reliable.

Assessment of pharyngeal airway space in patients with different maxillofacial skeletal abnormalities using cone beam computed tomography

Background. The patency of the pharyngeal airway has a far-reaching impact on craniofacial development. Conversely, the position of the maxillofacial skeletal components in certain disorders may lead to a compromised airway. Therefore, the evaluation of the airway is an essential step in treatment planning. Objectives. The basic aim of this study was to measure the pharyngeal air space volume in the patients with maxillofacial skeletal abnormalities (like Class II, Class III malocclusion, TMJ Ankylosis, Condylar abnormalities and Syndromic cases) and those without any skeletal abnormalities. The objectives were to assess the Linear, Cross-sectional, and Volumetric dimensions of the pharyngeal airway in patients with and without maxillofacial skeletal abnormalities. (Study and Control group) Materials and methods. The Study group included 49 patients with maxillofacial Skeletal abnormalities like Class II and Class III malocclusion, Temporomandibular Joint Ankylosis, Condylar abnormalities, Syndromic cases. 49 Control group patients did not present with any skeletal abnormalities. The Linear, Cross-sectional, and Volumetric dimensions of the pharyngeal airway in the Study group and Control group were calculated and compared within the groups. Statistical Analysis: Unpaired t -test, ANOVA test and Tukey’s Post Hoc analysis test were for the data analysis of the above study. Outcomes. The Anteroposterior dimension of the airway at the Superiormost level was found to be significantly greater in Class II (p-value-0.039), Class III (p-value-0.002), and Control groups (p-value &lt;0.001) when compared with the TMJ Ankylosis group. The Volume and Cross-sectional area of the airway at the most constricted level of the airway was found to be significantly greater in Class III (p-value &lt;0.001) and Control group (p-value 0.013, 0.003) respectively when compared with the TMJ Ankylosis group. Conclusions. The pharyngeal airway was narrowest anteroposteriorly at all three levels (Superior-most, Most constricted, and Inferior-most levels) in the TMJ Ankylosis group and widest in the Class III group. The least cross-sectional area was found in the TMJ Ankylosis group whereas the greatest was found in the Class III group. The airway volume in the TMJ Ankylosis group and Class II group is significantly lesser than that of the Control group.

KEMAMPUAN SISWA DALAM MENYELESAIKAN SOAL BANGUN RUANG GABUNGAN

This study aims to see how students' ability to solve problems related to surface area and volume of combined space builds. The research method used was qualitative descriptive involving 15 grade VIII students at a junior high school in Karawang Regency. The results showed that there was a variation in students' abilities, only a small percentage of students were able to solve the problem well, while most students still had difficulties. Common mistakes encountered are related to calculations and understanding the concept of building space that has not been fully mastered by most students. This information becomes an important basis for improving the quality of geometry learning in schools, focusing on areas that cause difficulties for students.

Modulated electrical performance of cross-linked polyethylene by grafted charge-attracting molecules for high voltage direct current cable insulation

In order to figure out the effects of charge-attracting molecules on the direct current electrical performance of crosslinked polyethylene (XLPE), the molecules with different structures and functional groups were grafted onto XLPE, and their space charge, volume resistivity and thermal stimulated depolarization current were investigated. Based on density function theory, the trap distribution and charge-attracting properties of the grafted XLPE were calculated. For the charge-attracting groups, the results indicate that with the grafted of trap molecules containing polar groups CO and N-H, the electron and hole traps are introduced and the ability of attracting negative charges and positive charges are extremely improved, respectively, resulting in the enhanced space charge hindering and suppressed resistivity. The benzene ring can form both electron and hole traps with relatively shallower energy level, and results in an improved space charge dissipation and decreased resistivity. For the combination of charge-attracting groups, the continuous arrangement of homogeneous charge-attracting groups can achieve an enhanced modification effect, and heterogeneous charge-attracting groups will attenuate the modification ability. For the molecule structure, the grafting of compact cyclic molecular can affect the electrostatic potential distribution on XLPE’s chain, and exhibits a stronger modification effect.

Amount Estimation Method for Food Intake Based on Color and Depth Images through Deep Learning.

In this paper, we propose an amount estimation method for food intake based on both color and depth images. Two pairs of color and depth images are captured pre- and post-meals. The pre- and post-meal color images are employed to detect food types and food existence regions using Mask R-CNN. The post-meal color image is spatially transformed to match the food region locations between the pre- and post-meal color images. The same transformation is also performed on the post-meal depth image. The pixel values of the post-meal depth image are compensated to reflect 3D position changes caused by the image transformation. In both the pre- and post-meal depth images, a space volume for each food region is calculated by dividing the space between the food surfaces and the camera into multiple tetrahedra. The food intake amounts are estimated as the difference in space volumes calculated from the pre- and post-meal depth images. From the simulation results, we verify that the proposed method estimates the food intake amount with an error of up to 2.2%.

Abstract 3391: Effects of repeated psychological stress on NNK-induced lung cancer development in young female mice

Abstract Lung cancer is the second most common cancer in both men and women in the US and the leading cause of cancer death. Among younger US women, lung cancer incidence rates have in recent years become higher than rates seen in men, despite comparable histories of tobacco use. The possible contribution of stress to higher lung cancer risk in young women has received little research attention despite preclinical evidence that exposure to stress-related neuroendocrine responses can cause DNA damage. The present study used a well-established lung cancer model in young female mice (in vivo exposure to NNK) along with a mouse stress model to explore their independent and combined effects on lung cancer development. In addition, we explored one possible biological pathway by chronic administration of a beta-adrenergic receptor blocker (propranolol). We also tested the use of in vivo imaging for repeated monitoring of tumor development over time. Cohort 1 (n=60) had 4 groups: Home cage control, NNK treatment alone, repeated stress (RS) alone and NNK+RS. Cohort 2 (n=60) had the same 4 groups with the addition of administration of propranolol in drinking water. Cohort 3 (n=48, imaging cohort) had 3 groups: Home cage control, NNK alone and NNK+RS. FVB/N (4-6 wk) were purchased from a commercial supplier and acclimated with gentle handling for two weeks. The repeated stress protocol began week-3 and continued for the duration of the study. It combined two well-established rodent models: social disruption stress via changes in cage mates at the time of cage cleaning (2x/week) and a 90-minute restraint stress immediately prior to cage change (1x/week). NNK or saline treatment began on week-4 (IP; 2x/week; 3 mg/injection) and continued for 4 weeks. 21 weeks after stress initiation, the mice in cohorts 1 and 2 were sacrificed, lungs removed, inflated and tumors counted and sized. Mice in cohort 3 were imaged by Hounsfield-calibrated micro-CT (μCT) at baseline, 14, 19 and 23 weeks. The entire lung space, excluding the heart, was defined as a volumetric region of interests (VOIs). The VOIs were subjected to thresholding to segment the lungs into air space and tissue space compartments. The volume of tissue space of each animal was ratioed against its own baseline tissue space volume. Results from Cohort 1 revealed significantly greater numbers and overall size of lung tumors in stressed mice that received NNK. No significant effects were seen in the absence of NNK. Results from Cohort 2 revealed no significant differences between stressed and unstressed groups treated with propranolol. Cohort 3 revealed a pattern of results with stressed mice generally showing the highest lung tumor volume levels (Hounsfield Units), which reached significance at 19 weeks in preliminary analyses. Conclusion: In this study, we found that repeated stress increased lung tumor burden in female mice treated with NNK, and that a beta-adrenergic pathway may be involved. Citation Format: Frank Jenkins, Laura P. Stabile, Jessie R. Nedrow, Kathryn Day, Joseph D. Latoche, Patrick M. Tarwater, Jessica Manculich, Dana H. Bovbjerg. Effects of repeated psychological stress on NNK-induced lung cancer development in young female mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3391.

Machine-learning recovery of foreground wedge-removed 21-cm light cones for high-z galaxy mapping

ABSTRACT Upcoming experiments will map the spatial distribution of the 21-cm signal over three-dimensional volumes of space during the Epoch of Reionization (EoR). Several methods have been proposed to mitigate the issue of astrophysical foreground contamination in tomographic images of the 21-cm signal, one of which involves the excision of a wedge-shaped region in cylindrical Fourier space. While this removes the k-modes most readily contaminated by foregrounds, the concurrent removal of cosmological information located within the wedge considerably distorts the structure of 21-cm images. In this study, we build upon a U-Net-based deep-learning algorithm to reconstruct foreground wedge-removed maps of the 21-cm signal, newly incorporating light-cone effects. Adopting the Square Kilometre Array as our fiducial instrument, we highlight that our U-Net recovery framework retains a reasonable level of reliability even in the face of instrumental limitations and noise. We subsequently evaluate the efficacy of recovered maps in guiding high-redshift galaxy searches and providing context to existing galaxy catalogues. This will allow for studies of how the high-redshift galaxy luminosity function varies across environments, and ultimately refine our understanding of the connection between the ionization state of the intergalactic medium and galaxies during the EoR.

Heart rate and breathing effects on attention and memory (HeartBEAM): study protocol for a randomized controlled trial in older adults

BackgroundIn healthy people, the “fight-or-flight” sympathetic system is counterbalanced by the “rest-and-digest” parasympathetic system. As we grow older, the parasympathetic system declines as the sympathetic system becomes hyperactive. In our prior heart rate variability biofeedback and emotion regulation (HRV-ER) clinical trial, we found that increasing parasympathetic activity through daily practice of slow-paced breathing significantly decreased plasma amyloid-β (Aβ) in healthy younger and older adults. In healthy adults, higher plasma Aβ is associated with greater risk of Alzheimer’s disease (AD). Our primary goal of this trial is to reproduce and extend our initial findings regarding effects of slow-paced breathing on Aβ. Our secondary objectives are to examine the effects of daily slow-paced breathing on brain structure and the rate of learning.MethodsAdults aged 50–70 have been randomized to practice one of two breathing protocols twice daily for 9 weeks: (1) “slow-paced breathing condition” involving daily cognitive training followed by slow-paced breathing designed to maximize heart rate oscillations or (2) “random-paced breathing condition” involving daily cognitive training followed by random-paced breathing to avoid increasing heart rate oscillations. The primary outcomes are plasma Aβ40 and Aβ42 levels and plasma Aβ42/40 ratio. The secondary outcomes are brain perivascular space volume, hippocampal volume, and learning rates measured by cognitive training performance. Other pre-registered outcomes include plasma pTau-181/tTau ratio and urine Aβ42. Recruitment began in January 2023. Interventions are ongoing and will be completed by the end of 2023.DiscussionOur HRV-ER trial was groundbreaking in demonstrating that a behavioral intervention can reduce plasma Aβ levels relative to a randomized control group. We aim to reproduce these findings while testing effects on brain clearance pathways and cognition.Trial registration ClinicalTrials.gov NCT05602220. Registered on January 12, 2023.