bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Learning and Training in the Post-Acute Stroke Phase
Authors: Krebs Hermano Igo , Hogan Neville , Aisen Mindy L. , Volpe Bruce T.
Published: July 2023

We are investigating the application of robotic and automation technology to assist in stroke rehabilitation. Cerebral vascular accident (stroke) annually affects over a quarter of a million people in the U.S. and is the most common diagnosis of patients admitted to rehabilitation hospitals. Current therapeutic practices are labor intensive and consist of a series of individualized sensory-motor exercise routines conducted in one-on-one sessions between the patient and the therapist. Whether this individualized sensory-motor therapy is important for a patient’s functional recovery remains controversial. Our effort have been concentrated on a) evaluating the safety and acceptability of robots in a clinical setting; b) evaluating the effectiveness of robot-aided neuro-rehabilitation; c) increasing our understanding of the process of post-traumatic recovery of sensory-motor function. Preliminary results of the pilot clinical trial can be found elsewhere [2][3].
Fluoroscopic Particle Tracking in a Model Aneurysm Using Traceable Droplets
Authors: Lieber B. B. , Rudin S. , Wakhloo A. K. , Stancampiano A. P. , Bednarek D. R.
Published: July 2023

Conventional angiographic techniques are limited by their ability to provide only streaklines of flow patterns and does not render quantitative analysis of the flow. In this study we examined the possibility of obtaining quantitative flow information by injecting insoluble droplets of contrast material into an aneurysm phantom. The phantom was connected to a recirculating flow apparatus. Pulsatile flow was employed with a working fluid mixture of 1:1 water glycerine solution. The flow patterns in the phantom were investigated using a fluoroscopic unit. Calibrated droplets of insoluble contrast media, Ethiodol, were injected at different locations in the channel carrying the aneurysm. Droplet paths were recorded at a rate of 30 frames per second. Peak flow velocity of the droplets was determined from displacement of the droplets between successive video frames and the known geometry of the model. The results of the video velocity analysis compared reasonably well with velocity values calculated from the measured flow rate by an electromagnetic flow meter.
Accuracy of Axial Wall Shear Stress Measurements From a Three Dimensional Particle Tracking System
Authors: Thacker Monica , Tsao RayChang , Jones Steven A.
Published: July 2023

An automated three-dimensional particle tracking system has been evaluated for its ability to measure axial wall shear stress in a biologically relevant flow system. The flow system and particles modeled the conditions of monocytes in a large artery stenosis. It is shown that wall shear stress can be accurately obtained and that the error is a function of shear rate, shear rate gradient, and distance from the wall.
Curvature Changes of the Left Anterior Descending Coronary Artery During the Cardiac Cycle
Authors: Gross Mark F. , VanFossen Douglas B. , Friedman Morton H.
Published: July 2023

A system was developed to track the position and curvature of the human coronary arteries during a cardiac cycle using bi-plane angiography. The system uses a time interpolation technique on one image plane to create simultaneous image pairs. The image pairs are then used to reconstruct the three-dimensional (3D) axes of the vessels over the cardiac cycle. From the axes, curvature measurements have been made on a portion of the left anterior descending artery (LAD) at approximately 30 different times during the cardiac cycle. Results show that the changes in curvature over the cardiac cycle vary considerably from point to point.
Flow and Particle Paths in Three-Dimensional Model Skeletal Muscle Ventricles
Authors: Iudicello F. , Henry F. S. , Collins M. W. , Shortland A. , Black R. , Jarvis J. C. , Salmons S.
Published: July 2023

Three-dimensional simulations of the flow in a model Skeletal Muscle Ventricle (SMV) were performed. Predicted flow patterns during ventricular filling were compared with experimental data from a physical model under identical conditions. The reliability of the numerical predictions was established by validation against in vitro data. Good agreement with the experiments was achieved. Particle pathlines in the three-dimensional model were also generated, and these will be used to estimate residence times in more realistic three-dimensional models.
Distal Anastomotic Intimal Hyperplasia in Human Aortocoronary Vein Grafts
Authors: Ojha Matadial , Butany Jagdish
Published: July 2023

Coronary artery bypass graft (CABG) surgery is a common way of treating the occlusive disease, atherosclerosis. However, these grafts tend to fail due to thrombosis from (i) surgical techniques and the diseased state of the native coronary artery a few months post-surgery[Lesperance et al., 1972; Campeau et al., 1975], and (ii) the development of intimal hyperplasia that acts a precursor for atherosclerosis and plaque rupture one or more years post-operatively [Grodin et al., 1979; Campeau et al., 1983]. Coronary vein grafts tend to occlude preferentially at the distal end-to-side anastomosis and less frequently at sites along the graft itself (i.e. the graft body) and at the proximal anastomosis [FitzGibbon et al., 1978, 1986].
The Influence of Muscle Contraction on the Kinematics of the Knee Joint
Authors: Andriacchi Thomas P. , Toney M. Kent , Dyrby Chris , Conley Arthur
Published: July 2023

There is a paucity of information on the interaction between muscle contraction and the kinematics of the knee. In particular, the anterior-posterior (AP) movement of the femur on the tibia has been described primarily from passive testing (2). The dynamic action of the extensor and flexor muscle groups at the knee can have a substantial influence on the AP movement of the femur on the tibia. This dynamic information is important for understanding a number of issues related to ligament reconstruction as well as the designs of total knee replacement. However, most knowledge of six degree of freedom knee kinematics is based on passive testing.
Markerless Three Dimensional Measurement of Knee Kinematics Using Single-Plane Fluoroscopy
Authors: Banks Scott A. , Banks Anne Z. , Cook Frank F. , Hodge W. Andrew
Published: July 2023

Kinematics of the normal, injured, or prosthetically replaced knee joint are a complex combination of rolling, gliding and rotational motions which are significantly influenced by the activity undertaken, the integrity of the ligaments and capsular structures, muscle activity, and articular geometry. Accurate kinematic information is critical to understanding the function and pathogenesis of the knee, particularly during weight bearing dynamic activities. The present study was undertaken to characterize the accuracy of a non-invasive fluoroscopic technique for measuring dynamic three-dimensional (3D) knee motions in individuals whose knees have not been prosthetically replaced. This technique utilizes orthogonal planar radiographic views of the knee to create a 3D contour model of consistently identifiable bony features for both the tibia and femur. The measurement technique is implemented by projecting the contour model onto digitized fluoroscopic images of the moving knee, and determining the translations and rotations which give the best correspondence between the projected contour model and the radiographic projection of the bone. Controlled in vitro assessment of the technique resulted in a rotational accuracy of 1.8 degrees and a sagittal plane translational accuracy of 1.2 mm.
Self Heating in III-V Transistors
Authors: Anholt Robert , Dettmer R. , Bozada C. , Cerny C. A. , Desalvo G. , Ebel J. , Gillespie J. , Havasy C. , Ito C. , Jenkins T. , Pettiford C. , Liou L. , Nakano K. , Nakano K. , Quach T. , Sewell J. , Via D.
Published: July 2023

The III-V integrated-circuits industry makes use of measured and modeled thermal impedances to model and to optimize transistor performance and to design circuits. In field effect transistors (FETs), heat is generated in a very small volume on the drain side of the gate, but models assume that it is generated in wide rectangular bars on the surface of the device. We describe electrical techniques for measuring the thermal impedances in FETs and in heterojunction bipolar transistors (HBTs). In HBTs the maximum power densities are limited by self heating, and we describe experimental studies of thermal shunt designs that reduce the thermal impedances.
Internal Temperature Distribution of a Vertical-Cavity Surface-Emitting Lasers Measured by Scanning Thermal Microscopy
Authors: Luo K. , Herrick R. W. H. , Majumdar A. , Petroff P.
Published: July 2023

This paper presents the first measurements of the temperature distribution inside a vertical-cavity surface-emitting laser. The peak temperature occurred at the intersection of the optical axis and the active region and increased with laser current. The peak temperature was found to be lower, by a factor of two, than numerical predictions and previous measurements using temperature-dependent shift in the output laser wavelength. Comparison of the temperature distribution, that is responsible for thermal lensing of the output laser mode, showed that the measured axial temperature distribution deviated significantly from numerical predictions, primarily due to heat sinking on the top surface near the p mirror. The measured radial temperature distributions along the quantum wells were in very good agreement with numerical predictions.
Nanojoule Thermal Transfer in Micromechanical Heterostructures
Authors: Berger Rüdiger , Gerber Christoph , Gimzewski James K. , Meyer Ernst , Güntherodt Hans-Joachim
Published: July 2023

We describe recent experiments on heat-transfer processes in silicon-nitride micromechanical heterostructures using nanoscale-science techniques. The influence of various media surrounding the structures, such as ethanol, air, and vacuum, on heat loss is discussed. Key factors investigated are thermal response time and thermomechanical sensitivity. Both the effects of ohmic and laser-irradiated heating are discussed. Using a heterostructured micromechanical calorimeter, heat-transfer processes at phase transitions are determined down to the nanojoule level.
Giant Reduction in Lateral Thermal Conductivity of Thin Nitride/Silicon/Oxide Membrane Measured With a Suspended Micro Structure
Authors: Zheng X. Y. , Li S. Z. , Chen M. , Wang K. L.
Published: July 2023

A suspended micro structure, a thermal bridge, was developed for measurement of lateral thermal conductivity of membrane materials. Integration of several polysilicon thermal elements (heaters and temperature sensors) with a membrane in a thermal bridge makes direct and accurate measurement of lateral thermal conductivity possible. A multilayer membrane composed of a layer of silicon nitride, a layer of monocrystalline silicon and a layer of silicon oxide was tested. Two measuring methods, a small signal differential method and an equivalent circuit method, were employed for evaluation of the thermal conductivity. The two-dimensional thermal conductivity of the membrane was found to be 0.34 × 10−6 W / K. This yields a lateral thermal conductivity of less than 2.2 W / m K for the silicon layer sandwiched in the membrane. In contrast, the thermal conductivity for bulk silicon is 148 W / m K. The accuracy of the result is also discussed.
Optimum Design of Microchannel Heat Sinks
Authors: Choquette S. F. , Faghri M. , Charmchi M. , Asako Y.
Published: July 2023

Analyses have been performed to obtain momentum and thermal characteristics in microchannel heat sinks. The applicability of existing correlations for friction factor and Nusselt number is investigated. The study revealed that existing correlations based on the analytical results can predict the heat sink performance to within the accuracy limits acceptable for use in design. A user friendly computer code has been developed as an aid in the optimum design of microchannel heat sinks. The program, using thermal resistance models, operates in two modes. In mode one, the performance capabilities, power requirements and efficiencies of an existing heat sink design are evaluated. Mode two is used as a design tool for heat sink optimization. In this mode, given the overall heat sink geometry, fluid and substrate properties, and inlet and outlet boundary conditions, the program determines the optimum channel spacing and fin thickness. Implementation of the optimization scheme is presented and its effectiveness is evaluated. Improvements of up to 45% in heat transfer rates are observed by analyzing thermal resistance surface plots for wide ranges of fin thickness and channel spacing. In addition, the idea of designing heat sinks for turbulent conditions rather than laminar are examined. The results show that significant reductions in the total thermal resistance are not achieved by designing for turbulent flow. In contrast, significantly higher pumping power requirements are realized when designing for turbulent flow with only slight improvement in overall thermal performance.
Navier-Stokes Simulations of a Novel Micropump
Authors: Sharatchandra M. C. , Sen Mihir , Gad-el-Hak Mohamed
Published: July 2023

A numerical study of flow in a novel viscous-based pumping device appropriate for microscale applications is described. The device, essentially consisting of a rotating cylinder eccentrically placed in a channel, is shown to be capable of generating a net flow against an externally imposed pressure gradient. Navier-Stokes simulations at low Reynolds numbers (O[1]) are carried out using a finite-volume approach to study the influence of various geometric parameters. Slip effects for gas flows are also briefly investigated. The numerical results indicate that the generated flow rate is a maximum when the cylinder is in contact with a channel wall and that an optimum plate spacing exists. These observations are in excellent agreement, both qualitatively and quantitatively, with a previous experimental study. Furthermore, it is shown that effective pumping is obtained even for considerably higher Reynolds numbers (O[100]), thereby extending the performance envelope of the proposed device to non-microscale applications as well. Finally, slip-flow effects appear to be significant only for Knudsen numbers greater than 0.1, which is important from the point of view of microscale applications.
Control of Flow Separation Using the EMEMS Approach: Proof of Concept Experiments
Authors: Sinha Sumon K. , Pal Dipankar , Banerjee Debjyoti
Published: July 2023

A driven flexible wall transducer has been developed for controlling unsteady and steady separating flows. The transducer consists of an array of electrostatically active strips under a flexible surface. The transducer is at first used as a sensor to detect wall pressure fluctuation frequencies which are believed to correspond to instabilities in the attached boundary layer and the separated shear layer. Next, selected transducer strips are driven at one of the sensed frequencies so as to introduce vortices close to the wall. Reattachment can occur when these vortices move downstream to the separated shear layer. This method has been used to control transcritical flow separation on a circular cylinder (Re of 1.5 × 105) and reattach marginally separated boundary layers on an NACA 0012 airfoil at Re values slightly under 106. To increase the strength and reduce the size of the controlling vortices, an elastomeric microstructured (EMEMS) version of this transducer is presented. The EMEMS transducer also has the potential of being robust and inexpensive.
Parametric Modeling of a Microaccelerometer Using I-Optimal Design of Experiments for Finite Element Analysis
Authors: Crary Selden B. , Gianchandani Yogesh B.
Published: July 2023

This paper describes the characterization of a microaccelerometer using optimal design of experiments. The criteria of I- and D-optimality are used to specify a near-minimal set of 36 to 38 input points in a five dimensional input space at which finite element analysis is performed and the suitability of the optimality criteria assessed. The accelerometer is comprised of a rigid proof mass and four suspension beams. Its response is determined as a function of acceleration along the input and cross-axes, temperature, and two structural variables, and the related performance compromises are identified. In particular, it is shown that the best performance is achieved when the suspension beams are attached to the middle of each side of the proof mass.
Thin Film Shape Memory Alloy Microactuators
Authors: Krulevitch P. , Lee A. P. , Ramsey P. B. , Trevino J. , Northrup M. A.
Published: July 2023

Thin film shape memory alloys (SMAs) have the potential to become a primary actuating mechanism for mechanical devices with dimensions in the micron to millimeter range requiring large forces over long displacements. In this paper, the thermo-mechanical behavior of shape memory films is presented, techniques for characterizing Ni-Ti-based shape memory films are evaluated, and design issues for SMA microactuators are discussed. The substrate curvature method is used to investigate the response of Ni-Ti-Cu SMA films, revealing recoverable stresses up to 510 MPa, transformation temperatures above 32°C, and hysteresis widths between near 10°C. Fatigue data shows that for small strains, applied loads up to 350 MPa can be sustained for thousands of cycles.
Development of a Finite Element Analysis-Based Numerical Solution for Virtual Rapid Prototyping of Piezoelectric Microelectromechanical Systems
Authors: Chung Won Jee , Feng Hongwei , von Preissig Fred J. , Ghasemi Nejhad Mehrdad N. , Yuh Junku
Published: July 2023

The application of Finite Element Analysis (FEA) to Piezoelectric Microelectromechanical Systems (P-MEMS) is explored. Some unusual features and challenges associated with the special materials and geometries involved are discussed. FEA modeling of simple devices containing piezoelectrically active thin-film sensors and actuators is presented. Zinc oxide was the piezoelectric material used. Static electromechanical analyses were performed on two structures. The resulting deformations and voltage outputs were in excellent agreement with analytical solutions or experimental measurements. A harmonic analysis was performed on a third structure, and the resonant frequency agreed with an analytical result. The choice of ANSYS as the FEA platform for our Virtual Rapid Prototyping system for P-MEMS is shown to be a suitable one. “Top down” modeling is the preferred approach.
Microflow System and Noncontact Transportation of DNA Molecule in Microflow Channels by Dielectrophoretic Force
Authors: Morishima Keisuke , Fukuda Toshio , Arai Fumihito , Yoshikawa Kenichi
Published: July 2023

In this paper, we propose a new approach to noncontact transportation of DNA molecules by dielectrophoretic force and the idea of the Micro DNA Flow System. Such systems can be made by using Microfabrication technology. At first, we designed a simple micro electrode-flow system and carried out experiments. Experimental demonstration of DNA transportation using dielectrophoretic force and direct observation of the DNA molecule in a non-uniform electric field was carried out with fluorescence microscopy. We showed a simple electrode design and the possibility of noncontact transportation of DNA molecules based on Micro DNA Flow System. We consider the possibility of the Micro DNA Flow System as one of the biomanipulation and automation systems for DNA sequencing in future.
Nonlinear Dynamics of Micromachined Rate Gyros
Authors: Ljung Per B. , Pisano Albert P.
Published: July 2023

The full nonlinear equations of motion are derived for a general angularly driven rate gyro. Sensitivity to cross-axis angular input rates and angular input accelerations are shown in simplified form for design purposes. The gyro drive and sense axes can be operated either nonresonantly or resonantly where the natural frequencies coincide with the forcing moment. The tuning requirements and increase in coriolis sensitivity for resonant operation are detailed. Using this tuning technique, a two input axis micromachined rate gyro has been fabricated which can sense 0.15 °/sec in a 20Hz bandwidth.
Sequential Solutions of Field Equations Using a Single BEM Model
Authors: Ljung Per B.
Published: July 2023

A new portable CAD tool is introduced allowing a single boundary element model to solve coupled nonlinear Laplace, Poisson and Navier field equations. The compact formulation of the model and discretized differential equations allows the software to be implemented on standard personal computers. The software is implemented in vectorized Matlab code making this a portable CAD implementation. Several 2D and 3D examples are given using common micromachined structures.
Design of a Self-Closing Compliant “Mouse Trap” for Micro Assembly
Authors: Saitou Kazuhiro , Jakiela Mark J.
Published: July 2023

A design of a micro latching fastener — a micro “mouse trap” — is presented, which has self-closing compliant latches that clamp a free planar part inserted between them. The self-closing of the latches is induced by the insertion of the part which releases the potential energy stored in the “cocked” state of the device, in the manner of a mouse trap. The closed latch can re-open by cocking the micro mouse trap. The self-closing action of the micro mouse trap allows the inaccurate insertion of the free part and leads to very accurate final positioning, with the insertion force required to induce the self-closing being very small. The micro mouse trap is also reusable since the release of the clamped part is done nondestructively. The micro mouse trap can be used, for instance, for assembly and temporal clamping/positioning of micro-scale parts, and electromechanical/opto-mechanical connectors.
Large Deflection Effects on Micro Diaphragms: A Theoretical and Experimental Study
Authors: Lin Liwei , Chu Huey-Chi
Published: July 2023

Large deflection effects on piezoresistive, diaphragm type pressure sensors have been observed and analyzed. Square and circular shape diaphragms with width (diameter) of 100 μm, thickness from 1.5 to 2.0 μm, have been fabricated and tested. Linearity errors due to large deflection effect have been characterized by classical theory of plates and shells and measured experimentally. It is found that not only the thickness of the diaphragm but also the lengths of the sensing resistors affect the linearity behavior of the pressure sensors. Maximum linearity errors within 0.2% FSS (Full Scale Span) on both square and circular shape pressure sensors have been recorded and analyzed. These characteristics are useful not only in pressure sensor designs but also in building the linearity compensation circuitry for other diaphragm based precision transducers.
A Novel Technique for Penetrator Velocity Measurement in Ballistic Penetration Studies
Authors: Espinosa Horacio D. , Lu Hung-Cheng , Xu Yueping
Published: July 2023

A novel experimental configuration that can simultaneously record projectile velocity histories and target back surface out-of-plane motion in penetration experiments has been developed. The technique was used to investigate failure mechanisms during ballistic impact of an S-2 glass fiber woven composite with 60% fiber volume fraction. Microscopy studies performed on recovered samples clearly show interply delamination, fiber breakage, ply inelasticity, and fiber kinking as the major failure modes in these composites. Recorded penetrator velocity histories indicate the failure process is rate dependent.

Three well defined regions with different failure zones are observed in the laminate. In a region at the rear of the target plate, Region A, extensive delamination between plies is seen leading to bulge formation. Damage is observed in front of the penetrator with substantial fiber shearing. In a middle region, Region B, tensile fiber failure and large fiber deflection, to accommodate the lateral expansion generated by the steel penetrator, are observed. At the projectile entrance, Region C, fiber microfracture followed by fiber tensile failure is believed to be the failure mode in this region. Noticeable delamination is also produced in plies close to the front specimen surface. Two major fiber failures are observed in the micrographs, fiber kinking and microcracking. Well defined kink bands are seen in Regions B and C on plies with fibers oriented perpendicular to the penetration direction. The formation of kink bands appear to be the result of compressive failure due to lateral motion of the plies away from the advancing steel penetrator.
Finite Strain Analysis of Deformations of Quasibrittle Material During Missile Impact and Penetration
Authors: Bažant Zdeněk P. , Adley Mark D. , Xiang Yuyin
Published: July 2023

The conference presentation deals with three problems involved in finite element analysis of the impact of missiles into reinforced concrete walls and their penetration through the walls: (1) Formulation of the constitutive law for complex nonlinear triaxial behavior of concrete, including the strain-softening damage; (2) extension of the formulation to very large finite strains; and (3) application of the model in dynamic finite element analysis. Only problem (2) is discussed in some detail in this brief paper. Because the Biot strain tensor has a clear physical meaning even for very large finite strains, its use is preferable in the fitting of complex triaxial test data. It is shown that the constitutive relation can be conveniently formulated as a relation of the Biot strain tensor to the back-rotated Cauchy stress tensor, and the justification of this form of the constitutive relation is given.
Extrusion of Low-Density Microcellular HIPS Foams Using CO2
Authors: Behravesh Amir H. , Park Chul B. , Venter Ronald D.
Published: July 2023

A continuous extrusion process for the manufacture of low-density microcellular polymer is presented. Microcellular polymers are foamed plastics characterized by a cell density greater than 109 cells/cm3 and a fully grown cell size on the order of 10 μm. The basic approach to the production of microcellular structures is to continuously form a polymer/gas solution, nucleate a large number of bubbles using rapid pressure drop, shape a nucleated polymer/gas solution under pressure, and induce a volume expansion to a desired expansion ratio. Successful completion of these steps in extrusion will enable the manufacture of microcellular foamed plastics with a high cell-population density.

Previous research on the continuous processing of microcellular polymers has focused on control of microcell nucleation in extrusion. This paper presents an effective means for the control of cell growth to achieve a desired expansion ratio with CO2 as a blowing agent in microcellular foam processing. Also, a strategy to prevent the deterioration of the cell-population density via cell coalescence during expansion is presented. The promotion of a desired volume expansion ratio and the prevention of the cell coalescence in microcellular foam processing were experimentally verified. By tailoring the extrusion processing parameters, microcellular HIPS foams with a cell density of 1010 cells/cm3 and a controlled expansion ratio in the range of 1.5 to 23 were obtained.
Net-Shape Forming of Sintered Microcellular Foam Parts
Authors: Seeler Karl A. , Billington Scott A. , Drake Bruce D. , Kumar Vipin
Published: July 2023

The time required to saturate a polymer with gas increases with the square of the diffusion length. This has effectively limited the application of the batch process of producing microcellular foam to thin parts. Saturating powdered polymer rather than solid polymer and then sintering the particles to create a net-shape microcellular part is an alternative technique. The advantage of sintering microcellular parts from saturated polymer powder is the great reduction in the diffusion length reduces saturation time from days to minutes. Saturation time is decoupled from part thickness.

A prototype has been designed and tested in which saturated polymer powder is blown into a mold under the pressure of the saturating gas. The absorbed gas plasticizes the polymer. The powder is compressed into a solid preform to remove macroscopic voids, increase the diffusion distance to slow gas desorption, and to increase thermal conductivity. The preform is then heated, the mold expanded, and microcellular part formed to net shape in a closed mold. Preliminary tests with polycarbonate, amorphous polyethylene terephtalate (PET-G), and cellulose acetate have been successful.
Longitudinal Development of Physical Characteristics and Function in Japanese Junior Rugby Union Players
Authors: Kumazaki Akira , Fujimoto Tomomi , Matsuura Yuiko
Published: July 2023

Purpose: To longitudinally investigate the development of physical characteristics and function during 3 years of high school among Japanese junior rugby players and examine the differences in these parameters between the positions. Methods: In 83 junior rugby players (forwards: n = 46, backs: n = 37) from one Japanese high school team who had participated in national high school competitions, anthropometric variables (height, body mass, fat and lean body mass, and body mass index), upper- and lower-body strength (eg, 1-repetition-maximum [1RM] bench press, isokinetic knee muscle strength at 60°/s and 180°/s), and sprint and jump performance were measured. Upper- and lower-body strength relative to body mass and lean body mass were also calculated. Results: All anthropometric indices improved with increasing age, and the values were higher in forwards than in backs (all P < .05). The 1-repetition maximum bench press (forwards: 40.8%, backs: 52.5%) and isokinetic knee strength (eg, extension at 60°/s, forwards: 15.4%, backs: 10.0%) improved with age (from 16 to 18 y), and they were higher in forwards than in backs (all P < .05). Meanwhile, the 1RM bench press relative to lean body mass did not differ between the positions. Isokinetic knee muscle strength at 60°/s and 180°/s relative to lean body mass and sprint and jump performance did not improve with age. Conclusion: These results indicate that Japanese junior rugby players need to develop larger physiques and continuously increase their lower-body strength to improve sprint and jump performance.
How do social media feed algorithms affect attitudes and behavior in an election campaign?
Authors: Guess Andrew M. , Malhotra Neil , Pan Jennifer , Barberá Pablo , Allcott Hunt , Brown Taylor , Crespo-Tenorio Adriana , Dimmery Drew , Freelon Deen , Gentzkow Matthew , González-Bailón Sandra , Kennedy Edward , Kim Young Mie , Lazer David , Moehler Devra , Nyhan Brendan , Rivera Carlos Velasco , Settle Jaime , Thomas Daniel Robert , Thorson Emily , Tromble Rebekah , Wilkins Arjun , Wojcieszak Magdalena , Xiong Beixian , de Jonge Chad Kiewiet , Franco Annie , Mason Winter , Stroud Natalie Jomini , Tucker Joshua A.
Published: July 2023

We investigated the effects of Facebook’s and Instagram’s feed algorithms during the 2020 US election. We assigned a sample of consenting users to reverse-chronologically-ordered feeds instead of the default algorithms. Moving users out of algorithmic feeds substantially decreased the time they spent on the platforms and their activity. The chronological feed also affected exposure to content: The amount of political and untrustworthy content they saw increased on both platforms, the amount of content classified as uncivil or containing slur words they saw decreased on Facebook, and the amount of content from moderate friends and sources with ideologically mixed audiences they saw increased on Facebook. Despite these substantial changes in users’ on-platform experience, the chronological feed did not significantly alter levels of issue polarization, affective polarization, political knowledge, or other key attitudes during the 3-month study period.
Observation of universal Hall response in strongly interacting Fermions
Authors: Zhou T.-W. , Cappellini G. , Tusi D. , Franchi L. , Parravicini J. , Repellin C. , Greschner S. , Inguscio M. , Giamarchi T. , Filippone M. , Catani J. , Fallani L.
Published: July 2023

The Hall effect, which originates from the motion of charged particles in magnetic fields, has deep consequences for the description of materials, extending far beyond condensed matter. Understanding such an effect in interacting systems represents a fundamental challenge, even for small magnetic fields. In this work, we used an atomic quantum simulator in which we tracked the motion of ultracold fermions in two-leg ribbons threaded by artificial magnetic fields. Through controllable quench dynamics, we measured the Hall response for a range of synthetic tunneling and atomic interaction strengths. We unveil a universal interaction-independent behavior above an interaction threshold, in agreement with theoretical analyses. The ability to reach hard-to-compute regimes demonstrates the power of quantum simulation to describe strongly correlated topological states of matter.
Reshares on social media amplify political news but do not detectably affect beliefs or opinions
Authors: Guess Andrew M. , Malhotra Neil , Pan Jennifer , Barberá Pablo , Allcott Hunt , Brown Taylor , Crespo-Tenorio Adriana , Dimmery Drew , Freelon Deen , Gentzkow Matthew , González-Bailón Sandra , Kennedy Edward , Kim Young Mie , Lazer David , Moehler Devra , Nyhan Brendan , Rivera Carlos Velasco , Settle Jaime , Thomas Daniel Robert , Thorson Emily , Tromble Rebekah , Wilkins Arjun , Wojcieszak Magdalena , Xiong Beixian , de Jonge Chad Kiewiet , Franco Annie , Mason Winter , Stroud Natalie Jomini , Tucker Joshua A.
Published: July 2023

We studied the effects of exposure to reshared content on Facebook during the 2020 US election by assigning a random set of consenting, US-based users to feeds that did not contain any reshares over a 3-month period. We find that removing reshared content substantially decreases the amount of political news, including content from untrustworthy sources, to which users are exposed; decreases overall clicks and reactions; and reduces partisan news clicks. Further, we observe that removing reshared content produces clear decreases in news knowledge within the sample, although there is some uncertainty about how this would generalize to all users. Contrary to expectations, the treatment does not significantly affect political polarization or any measure of individual-level political attitudes.
Comment on “Ultrastructure reveals ancestral vertebrate pharyngeal skeleton in yunnanozoans”
Authors: Zhang Xi-guang , Pratt Brian R.
Published: July 2023

Tian
et al
. (Reports, 8 July 2022, p. 218) claim that Cambrian yunnanozoan animals are stem vertebrates, based partly on their observation at the nanometer scale of microfibrillar tissue located in the branchial arches. They interpret this to represent cellular cartilage with an extracellular matrix of microfibrils. Instead, we argue that the ‘microfibrils’ are more likely modern organic contamination.
Tandem propane dehydrogenation and surface oxidation catalysts for selective propylene synthesis
Authors: Wang Wei , Chen Sai , Pei Chunlei , Luo Ran , Sun Jiachen , Song Hongbo , Sun Guodong , Wang Xianhui , Zhao Zhi-Jian , Gong Jinlong
Published: July 2023

Direct propane dehydrogenation (PDH) to propylene is a desirable commercial reaction but is highly endothermic and severely limited by thermodynamic equilibrium. Routes that oxidatively remove hydrogen as water have safety and cost challenges. We coupled chemical looping–selective hydrogen (H
2
) combustion and PDH with multifunctional ferric vanadate–vanadium oxide (FeVO
4
-VO

x

) redox catalysts. Well-dispersed VO

x

supported on aluminum oxide (Al
2
O
3
) provides dehydrogenation sites, and adjacent nanoscale FeVO
4
acts as an oxygen carrier for subsequent H
2
combustion. We achieved an integral performance of 81.3% propylene selectivity at 42.7% propane conversion at 550°C for 200 chemical looping cycles for the reoxidization of FeVO
4
. Based on catalytic experiments, spectroscopic characterization, and theory calculations, we propose a hydrogen spillover–mediated coupling mechanism. The hydrogen species generated at the VO

x

sites migrated to adjacent FeVO
4
for combustion, which shifted PDH toward propylene. This mechanism is favored by the proximity between the dehydrogenation and combustion sites.
Face value
Authors: Thorp H. Holden
Published: July 2023

When TheFacebook.com went live in February of 2004, social media quickly became an integral part of life. Old friends rediscovered each other, pet photography flourished, and the way human attention on the internet was distributed was altered forever. As Ben Smith describes in his recent book,
Traffic
, before Facebook (now Meta) became widely adopted, aggregators like The Huffington Post and the Drudge Report were the main drivers of traffic to websites. Now they have been supplanted by social media platforms. This has transformed the internet business, politics, and journalism. Along the way, Facebook has accumulated a treasure trove of social science data on human reading habits and engagement. In this issue,
Science
is publishing three research papers and a Policy Forum that arose from an innovative partnership between Meta and academic researchers and illuminate our understanding of American political behavior.
Shaky ground
Authors: Popkin Gabriel
Published: July 2023

A company called Indigo is paying farmers to trap carbon in their soils. Some researchers say the climate benefits are dubious
Draft genome sequences of two strains of
Staphylococcus aureus
isolated from mastitis-infected camel in Kajiado County, Kenya
Authors: Mwangi Kamau , Gachogo Rachael , Masila Ednah , Ogali Irene , Langat Nathan , Onywera Ruth , Malonza Vincent , Wesonga Hezron , Maichomo Monicah , Murungi Edwin
Published: July 2023

We report the draft genome sequences of two
Staphylococcus aureus
strains isolated from a mastitis-infected camel in Kajiado County, Kenya. The 2,739,512-bp and 3,025,943-bp draft genomes coding for 2,577 and 2,889 protein sequences, respectively, provide invaluable data for the computational design of a camel mastitis subunit vaccine.
Rapid fluvial remobilization of sediments deposited by the 2021 Chamoli disaster, Indian Himalaya
Authors: Westoby Matthew J. , Dunning Stuart A. , Carrivick Jonathan L. , Coulthard Thomas J. , Sain Kalachand , Kumar Amit , Berthier Etienne , Haritashya Umesh K. , Shean David E. , Azam Mohd. Farooq , Upadhyay Kavita , Koppes Michele , McCourt Harley R. , Shugar Dan H.
Published: July 2023

High-magnitude mass flows can have a pervasive geomorphological legacy, yet the short-term response of valley floors to such intense disturbances is poorly known and poses significant observational challenges in unstable landscapes. We combined satellite remote sensing, numerical modeling, and field observations to reconstruct the short-term geomorphological response of river channels directly affected by the 7 February 2021 ice-rock avalanche–debris flow in Chamoli district, Uttarakhand, India. The flow deposited 10.4 ± 1.6 Mm3 of sediment within the first 30 km and in places reset the channel floor to a zero-state condition, requiring complete fluvial re-establishment. In the 12 months post-event, 7.0 ± 1.5 Mm3 (67.2%) of the deposit volume was removed along a 30-km-long domain and the median erosion rate was 2.3 ± 1.1 m a–1. Most sediment was removed by pre-monsoon and monsoon river flows, which conveyed bedload waves traveling at 0.1–0.3 km day–1 and sustained order-of-magnitude increases in suspended sediment concentrations as far as 85 km from the event source. Our findings characterize a high-mountain fluvial cascade with a short relaxation time and high resilience to a high-magnitude geomorphological perturbation. This system response has wider implications, notably for water quality and downstream hydropower projects, which may be disrupted by elevated bedload and suspended sediment transport.
PREhabilitation of CAndidates for REnal Transplantation (PreCareTx) study: protocol for a hybrid type I, mixed method, randomised controlled trial
Authors: Quint Evelien E , Haanstra Avril J , van der Veen Yvonne , Maring Heleen , Berger Stefan P , Ranchor Adelita , Bakker Stephan J L , Finnema Evelyn , Pol Robert A , Annema Coby
Published: July 2023

Introduction

Kidney transplant candidates (KTCs) need to be in optimal physical and psychological condition prior to surgery. However, KTCs often experience compromised functional capacity which can be characterised as frailty. Prehabilitation, the enhancement of a person’s functional capacity, may be an effective intervention to improve the health status of KTCs. The PREhabilitation of CAndidates for REnal Transplantation (PreCareTx) study aims to examine the effectiveness of a multimodal prehabilitation programme on the health status of KTCs, and to explore the potential of implementation of prehabilitation in daily clinical practice.

Methods and analysis

This study uses a single centre, effectiveness-implementation hybrid type I study design, comprised of a randomised controlled trial and a mixed-methods study. Adult patients who are currently on the transplant waiting list or are waitlisted during the study period, at a university medical centre in The Netherlands, will be randomly assigned to either prehabilitation (n=64) or care as usual (n=64) groups. The prehabilitation group will undergo a 12-week home-based, tailored prehabilitation programme consisting of physical and/or nutritional and/or psychosocial interventions depending on the participant’s deficits. This programme will be followed by a 12-week maintenance programme in order to enhance the incorporation of the interventions into daily life. The primary endpoint of this study is a change in frailty status as a proxy for health status. Secondary endpoints include changes in physical fitness, nutritional status, psychological well-being, quality of life and clinical outcomes. Tertiary endpoints include the safety, feasibility and acceptability of the prehabilitation programme, and the barriers and facilitators for further implementation.

Ethics and dissemination

Medical ethical approval was granted by the Medical Ethics Committee Groningen, Netherlands (M22.421). Written informed consent will be obtained from all participants. The results will be disseminated at international conferences and in peer-reviewed journals.

Trial registration number

ClinicalTrials.gov,NCT05489432.
Multilevel interventions as climate change adaptation response to protect maternal and child health: a scoping review protocol
Authors: Lokmic-Tomkins Zerina , Bhandari Dinesh , Watterson Jessica , Pollock Wendy E , Cochrane Lindy , Robinson Eddie , Su Tin Tin
Published: July 2023

Introduction

Growing evidence suggests that climate change-related extreme weather events adversely impact maternal and child health (MCH) outcomes, which requires effective, sustainable and culturally appropriate interventions at individual, community and policy levels to minimise these impacts. This scoping review proposes to map the evidence available on the type, characteristics and outcomes of multilevel interventions implemented as adaptational strategies to protect MCH from the possible adverse effects of climate change.

Methods

The following databases will be searched: Embase, MEDLINE, Emcare, EPPI-Centre database of health promotion research (BiblioMap) EPPI-Centre Database for promoting Health Effectiveness Reviews (DoPHER), Global Health, CINAHL, Joanna Briggs Institute EBP Database, Maternity and Infant Care Database, Education Resource Information Center, PsycINFO, Scopus, Web of Science and Global Index Medicus, which indexes Latin America and the Caribbean, Index Medicus for the South-East Asia Region, African Index Medicus, Western Pacific Region Index Medicus. Cochrane Central Register of Controlled Trials, WHO International Clinical Trials Registry Platform, ClinicalTrials.gov, conference proceedings, thesis and dissertations, policy and guidelines and their reference lists will also be searched. Two reviewers will independently screen titles and abstracts and full text based on predefined eligibility criteria. The Preferred Reporting Items for Systematic Reviews and Meta-analyses Extension for Scoping Reviews using the Population, Concept and Context framework and the Template for Intervention Description and Replication checklist will be used to structure and report the findings.

Ethics and dissemination

Ethics permission to conduct the scoping review is not required as the information collected is publicly available through databases. Findings will be disseminated through a peer-reviewed publication and conference presentations.
Diagnosis and endovascular management of vasospasm after aneurysmal subarachnoid hemorrhage — survey of real-life practices
Authors: Guenego Adrien , Fahed Robert , Rouchaud Aymeric , Walker Gregory , Faizy Tobias D , Sporns Peter B , Aggour Mohamed , Jabbour Pascal , Alexandre Andrea M , Mosimann Pascal John , Dmytriw Adam A , Ligot Noémie , Sadeghi Niloufar , Dai Chengbo , Hassan Ameer E , Pereira Vitor M , Singer Justin , Heit Jeremy J , Taccone Fabio Silvio , Chen Michael , Fiehler Jens , Lubicz Boris
Published: July 2023

Background

Vasospasm and delayed cerebral ischemia (DCI) are the leading causes of morbidity and mortality after intracranial aneurysmal subarachnoid hemorrhage (aSAH). Vasospasm detection, prevention and management, especially endovascular management varies from center to center and lacks standardization. We aimed to evaluate this variability via an international survey of how neurointerventionalists approach vasospasm diagnosis and endovascular management.

Methods

We designed an anonymous online survey with 100 questions to evaluate practice patterns between December 2021 and September 2022. We contacted endovascular neurosurgeons, neuroradiologists and neurologists via email and via two professional societies – the Society of NeuroInterventional Surgery (SNIS) and the European Society of Minimally Invasive Neurological Therapy (ESMINT). We recorded the physicians’ responses to the survey questions.

Results

A total of 201 physicians (25% [50/201] USA and 75% non-USA) completed the survey over 10 months, 42% had >7 years of experience, 92% were male, median age was 40 (IQR 35–46). Both high-volume and low-volume centers were represented. Daily transcranial Doppler was the most common screening method (75%) for vasospasm. In cases of symptomatic vasospasm despite optimal medical management, endovascular treatment was directly considered by 58% of physicians. The most common reason to initiate endovascular treatment was clinical deficits associated with proven vasospasm/DCI in 89%. The choice of endovascular treatment and its efficacy was highly variable. Nimodipine was the most common first-line intra-arterial therapy (40%). Mechanical angioplasty was considered the most effective endovascular treatment by 65% of neurointerventionalists.

Conclusion

Our study highlights the considerable heterogeneity among the neurointerventional community regarding vasospasm diagnosis and endovascular management. Randomized trials and guidelines are needed to improve standard of care, determine optimal management approaches and track outcomes.