Desired Intensity Research Articles

A Multielectrode Array-Based Recording System for Analyzing Ultrasound-Driven Neural Responses in Brain Slices in vitro.

Ultrasound stimulation is expected to be useful for transcranial local and deep stimulation of the brain, which is difficult to achieve using conventional electromagnetic stimulation methods. Previous ultrasound stimulation experiments have used various types of acute in vitro preparations, including hippocampus slices from rodents and Caenorhabditis elegans tissue. For in vivo preparations, researchers have used the cortices of rodents as targets for transcranial ultrasound stimulation. However, no previous studies have used in vitro ultrasound stimulation in rodent cortical slices to examine the mechanisms of ultrasound-driven central neural circuits. Here we demonstrate the optimal experimental conditions for an in vitro ultrasound stimulation system for measuring activity in brain slices using a multielectrode array substrate. We found that the peak amplitudes of the ultrasound-evoked cortical responses in the brain slices depend on the intensities and durations of the ultrasound stimulation parameters. Thus, our findings provide a new in vitro experimental setup that enables activation of a brain slice via ultrasound stimulation. Accordingly, our results indicate that choosing the appropriate ultrasound waveguide structure and stimulation parameters is important for producing the desired intensity distribution in a localized area within a brain slice. We expect that this experimental setup will facilitate future exploration of the mechanisms of ultrasound-driven neural activity.

The Effect of the Addition Turmeric on Selected Quality Characteristics of Duck Burgers Stored under Refrigeration

The aim of the study was to evaluate the effects of turmeric supplementation on selected quality features, oxidative stability, and the safety of duck meat burgers. Four burger variants, namely I–control, no additive, II–with turmeric powder, III–with turmeric extract, and IV–with turmeric paste, were tested. The pH, WHC, colour parameters on the CIE L*a*b* scale, finished products’ shear force, TBARS index, and the total number of microorganisms were determined while performing sensory evaluations. Tests were carried out after 24 h, 6, 12, and 18 days of refrigerated storage (4 ± 2 °C). The addition of turmeric powder and paste significantly limited lipid oxidation processes in vacuum-packed duck meat burgers over an 18-day period. Although lipid oxidation processes accelerated after 6 days in all burger variants, burgers with powdered turmeric powder showed the lowest TBARS index values and limited total microorganism increases. Turmeric paste and powder additions resulted in decreased pH, increased water retention, and lighter colouration in refrigerated products. These additives were deemed acceptable during sensory evaluation. The most desirable aroma and taste, including juiciness, were in burgers with turmeric paste addition, while burgers with powdered additions were rated higher for their desired aroma and intensity of taste.

A Simple Auxiliary Model for Field Amplitude Shaping in Complex Environments, and Application to MRI Shimming

The canonical problem of designing the complex excitations feeding an array such to ensure a desired field intensity distribution inside a given region of interest, while keeping it under control in some other regions, is addressed. To this end, an auxiliary physics inspired model for the induced total field is proposed, whose off-line analysis allows a simplified approach to understand the convenient and non-convenient field interferences between canonical solutions for the induced total field, that are zero order Bessel functions. Moreover, its analysis drastically reduces the computational burden associated to the multi-control points based approaches. The problem at hand plays a key role in many different applications, including radio communications, wireless power transfer as well as hyperthermia treatment planning, and in this paper attention is paid to radiofrequency shimming in Magnetic Resonance Imaging. In fact, the proposed model and tools are tailored to the challenging case of leveling of the magnetic field intensity within an MRI scanner and in case of a bidimensional realistic head phantom.

Denaturation of the SARS-CoV-2 spike protein under non-thermal microwave radiation

SARS-CoV-2, the virus that causes COVID-19, is still a widespread threat to society. The spike protein of this virus facilitates viral entry into the host cell. Here, the denaturation of the S1 subunit of this spike protein by 2.45 GHz electromagnetic radiation was studied quantitatively. The study only pertains to the pure electromagnetic effects by eliminating the bulk heating effect of the microwave radiation in an innovative setup that is capable of controlling the temperature of the sample at any desired intensity of the electromagnetic field. This study was performed at the internal human body temperature, 37 °C, for a relatively short amount of time under a high-power electromagnetic field. The results showed that irradiating the protein with a 700 W, 2.45 GHz electromagnetic field for 2 min can denature the protein to around 95%. In comparison, this is comparable to thermal denaturation at 75 °C for 40 min. Electromagnetic denaturation of the proteins of the virus may open doors to potential therapeutic or sanitation applications.

Time-averaged image projection through a multimode fiber.

Many disciplines, ranging from lithography to opto-genetics, require high-fidelity image projection. However, not all optical systems can display all types of images with equal ease. Therefore, the image projection quality is dependent on the type of image. In some circumstances, this can lead to a catastrophic loss of intensity or image quality. For complex optical systems, it may not be known in advance which types of images pose a problem. Here we show a new method called Time-Averaged image Projection (TAP), allowing us to mitigate these limitations by taking the entire image projection system into account despite its complexity and building the desired intensity distribution up from multiple illumination patterns. Using a complex optical setup, consisting of a wavefront shaper and a multimode optical fiber illuminated by coherent light, we succeeded to suppress any speckle-related background. Further, we can display independent images at multiple distances simultaneously, and alter the effective sharpness depth through the algorithm. Our results demonstrate that TAP can significantly enhance the image projection quality in multiple ways. We anticipate that our results will greatly complement any application in which the response to light irradiation is relatively slow (one microsecond with current technology) and where high-fidelity spatial distribution of optical power is required.

Advanced model-based controller for cyber-physical shot peening process

This study reports new development of a practical model-based controller (namely model predictive control, MPC) for shot peening, which is the first application to such a process for fully automated operation. In particular, the feedback MPC is developed based on a process model that links inlet air pressure of the machine to air pressure at a peening nozzle. In addition, a proxy model is developed to link measurement variable(s) to peening intensity as the intensity cannot be measured online for real-time feedback control. During process control, the process model is used to simulate future dynamics of the peening process to guide the controller for optimal control action, while the proxy model translates the setting intensity to air pressure reference set-point for real-time tracking. Both the controller and model development rely on the physical machine’s constraints and capabilities. The pressure sensors and sensor locations are carefully selected to ensure controllability and observability. Single input/single output feedback MPC with future process pre-view capability is developed and integrated into the actual shot peening machine. The MPC has been demonstrated and validated using both in-silico and onsite controls for different scenarios. The obtained results show that the developed MPC is stable, robust, and accurate as it can automatically adjust inlet air pressure to attain the desired intensity. Finally, MPC can also help to reduce up to 25% of production cost by eliminating the cost, time, materials waste, and labor in performing experimental trials to build the saturation curve for actual operational guidance.

Reproducibility of Glucose Fluctuations Induced by Moderate Intensity Cycling Exercise in Persons with Type 1 Diabetes.

Aims The purpose was to assess the reproducibility of glucose changes during three sessions of standardized moderate intensity continuous training of cycling on an individual level in people with type 1 diabetes. Methods Twelve adults (six females) with type 1 diabetes performed three test sessions on an ergometer bicycle (30 min, 67% of predicted heart rate) on three different days. The participants were 36.5 (26.6-45.5) (median, IQR) years old, and their HbA1c was 65 ± 15 mmol/mol (mean ± SD). Two hours before the tests, the participants had a standard meal. Interstitial glucose (IG) and capillary glucose (CG) were measured using an iPro2 Medtronic continuous glucose monitor and the Bayer Contour XT-device, respectively. Prior to the test sessions, resting heart rate was measured using a digital blood pressure monitor to estimate the desired intensity of the exercise. Results The average within-participant relationship between the average slope in glucose during sessions 2 and 1 was in IG -0.29 (95% CI -1.11; 0.58) and in CG -0.04 (-0.68; 0.77). Between sessions 3 and 2, IG is 0.18 (-0.27; 0.64) and in CG 0.13 (-0.25; 0.55). Between sessions 3 and 1, IG was 0.06 (-0.57; 0.71) and in CG 0.06 (-0.39; 0.52). The results indicate low reproducibility at participant levels and remained unchanged after adjustment for baseline glucose values. Conclusion On an individual level, the glucose declines during three standardized sessions of PA were not associated with identical responses of the measured IG and CG levels. An overall anticipated decline of glucose concentrations was found in the moderate intensity cycling sessions. This highlights the importance of regular CG measurements during and after physical activity and awareness towards potential exercise-induced hypoglycemia in persons with type 1 diabetes.

On Neglecting Free-Stream Turbulence in Numerical Simulation of the Wind-Induced Bias of Snow Gauges

Numerical studies of the wind-induced bias of precipitation measurements assume that turbulence is generated by the interaction of the airflow with the gauge body, while steady and uniform free-stream conditions are imposed. However, wind is turbulent in nature due to the roughness of the site and the presence of obstacles, therefore precipitation gauges are immersed in a turbulent flow. Further to the turbulence generated by the flow-gauge interaction, we investigated the natural free-stream turbulence and its influence on precipitation measurement biases. Realistic turbulence intensity values at the gauge collector height were derived from 3D sonic anemometer measurements. Large Eddy Simulations of the turbulent flow around a chimney-shaped gauge were performed under uniform and turbulent free-stream conditions, using geometrical obstacles upstream of the gauge to provide the desired turbulence intensity. Catch ratios for dry snow particles were obtained using a Lagrangian particle tracking model, and the collection efficiency was calculated based on a suitable particle size distribution. The collection efficiency in turbulent conditions showed stronger undercatch at the investigated wind velocity and snowfall intensity below 10 mm h−1, demonstrating that adjustment curves based on the simplifying assumption of uniform free-stream conditions do not accurately portray the wind-induced bias of snow measurements.

Tunable optical tweezers by dynamically sculpting the phase profiles of light

We propose an optical tweezer with tunable potential wells, by dynamically manipulating the phase gradient of light. Using our proposed method to design holograms, we can obtain desirable phase profiles and intensity distributions of optical traps. Optical force arising from phase gradient creates tunable potential wells for versatile optical nanomanipulation, such as trapping nanoparticles in peanut-shaped optical spots, positioning and shifting nanoparticles in optical gears, and controllable transport, as demonstrated in our experiments. The tunable optical tweezer has several merits including flexible design, easy control and high tunability, which provides a new tool for exploring novel functions in optical nanomanipulation.

Control of the intensity distribution along the light spiral generated by a generalized spiral phase plate

This paper proposes a method for shaping a light spiral with the desired intensity and phase distributions based on the addition of an angular-dependent amplitude distribution to the phase transmission function of a generalized spiral phase plate. An expression for the amplitude distribution of the illuminating beam, which provides a given intensity distribution in the focal plane along the light spiral, was derived, with the numerically and experimentally obtained results confirming the analytical calculations. The ability to control the phase and intensity gradient along the generated light curves allows one to shape the desired transverse energy flow distribution in the focal plane, which is important for optical manipulation of nano- and microparticles as demonstrated by the laser guiding of trapped 5 µm polystyrene microspheres.

Random Finite Set Theory and Centralized Control of Large Collaborative Swarms

Controlling large swarms of robotic agents presents many challenges, including, but not limited to, computational complexity due to a large number of agents, uncertainty in the functionality of each agent in the swarm, and uncertainty in the swarm’s configuration. This work generalizes the swarm state using random finite set (RFS) theory and solves a centralized control problem with a quasi-Newton optimization through the use of model predictive control (MPC) to overcome the aforementioned challenges. This work uses the RFS formulation to control the distribution of agents assuming an unknown or unspecified number of agents. Computationally efficient solutions are also obtained via the MPC version of the iterative linear quadratic regulator (ILQR), a variant of differential dynamic programming. Information divergence is used to define the distance between the swarm RFS and the desired swarm configuration through the use of the modified distance. Simulation results using MPC and ILQR show that the swarm intensity converges to the desired intensity. Additionally, the RFS control formulation is shown to be very flexible in terms of the number of agents in the swarm and configuration of the desired Gaussian mixtures. Lastly, the ILQR and the Gaussian mixture probability hypothesis density filter are used in conjunction to solve a spacecraft relative motion problem with imperfect information to show the viability of centralized RFS control for this real-world scenario.

Sustainability of an Activity Node in Global Supply Chains

Urban shrinkage is a remarkable phenomenon that cannot be convincingly explained by existing theories on urban growth and is closely linked to the global supply chain (SC) nodes in the labour market. This paper shows how a municipality in which an activity SC cell (production or service) is located as a node in the SC graph can be made more attractive for industrial activities and human resources, more sustainable, and less shrinking, through appropriate tax policies and investments in the infrastructure of the central places—cities where production or services are located. To this end, we developed the decision support model for the joint control of urban rightsizing by SC managers and local authorities. In the model we linked the extended material requirements problem (MRP) with a normalised asymmetric gravity model. The paper outlines how local authorities and institutions, when planning for the growing intensity of production or services, in a city where the number of workers is insufficient, should take into account the impact of taxation as well as investment in the infrastructure of a municipality, and not just net wages, in order to attract human resources. They need a decision support model for their negotiations on the rightsizing of the city. The objective was to develop a model of fiscal mechanisms in the interactive decision making processes of local authorities and SC managers to control the availability of labour in the city where production or services are running and need to grow because SC managers want to increase production or services but the available labour force is shrinking. A case study in Slovenia shows how local authorities and SC managers should work together to maintain a sustainable activity cell in a functional region of the urban agglomeration where this production or service is located. It models how to plan the rightsizing. Such an integrated policy best achieves the desired intensity of the supply chain, thereby avoiding the relocation of activities outside the region, which allows unsustainable flows of human resources and uncontrolled shrinking of a city or region.

Progressive resistance training for adolescents with cerebral palsy: the STAR randomized controlled trial.

To evaluate the effect of progressive resistance training of the ankle plantarflexors on gait efficiency, activity, and participation in adolescents with cerebral palsy (CP). Sixty-four adolescents (10-19y; 27 females, 37 males; Gross Motor Function Classification System [GMFCS] levels I-III) were randomized to 30 sessions of resistance training (10 supervised and 20 unsupervised home sessions) over 10 weeks or usual care. The primary outcome was gait efficiency indicated by net nondimensional oxygen cost (NNcost). Secondary outcomes included physical activity, gross motor function, participation, muscle strength, muscle and tendon size, and muscle and tendon stiffness. Analysis was intention-to-treat. Median attendance at the 10 supervised sessions was 80% (range 40-100%). There was no between-group difference in NNcost at 10 (mean difference: 0.02, 95% confidence interval [CI] -0.07 to 0.11, p=0.696) or 22 weeks (mean difference: -0.08, 95% CI -0.18 to 0.03, p=0.158). There was also no evidence of between-group differences in secondary outcomes at 10 or 22 weeks. There were 123 adverse events reported by 27 participants in the resistance training group. We found that 10 supervised sessions and 20 home sessions of progressive resistance training of the ankle plantarflexors did not improve gait efficiency, muscle strength, activity, participation, or any biomechanical outcome among adolescents with CP. Thirty sessions of progressive resistance training of the ankle plantarflexors over 10 weeks did not improve gait efficiency among ambulatory adolescents with cerebral palsy. Resistance training did not improve muscle strength, activity, or participation. Ninety percent of participants experienced an adverse event. Most adverse events were expected and no serious adverse events were reported.

Numerical Optimization of Waveguide Structure in an Ultrasound Brain Stimulation System Using the FDTD Method

Ultrasound stimulation is expected to be capable of transcranial deep and local stimulation to the brain, which is difficult to achieve using conventional electromagnetic stimulation. Once an ultrasound transducer is determined, however, its physical characteristics are hard to change. For obtaining the appropriate irradiation properties, we used a computer simulation of our experimental setup to characterize the optimal shape and size of a waveguide attached to the tip of an ultrasound transducer to target a specific brain region. We obtained an optimal waveguide structure to produce the desired intensity distribution. Our next challenge is to test in our physical setup. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Photoinduced Tunable and Reconfigurable Electronic and Photonic Devices Using a Silk-Based Diffractive Optics Platform.

A remarkable feature of modern electronic and photonic devices is the ability to maintain their geometric and physical properties in various circumstances for practical applications. However, there is an increasing demand for reconfigurable devices and systems that can be triggered or switched by external stimuli to change geometric, physical, and/or biochemical properties to meet specific requirements such as compact, lightweight, energy‐efficient, and tunable features. Here, a set of phototunable and photoreconfigurable electronic and photonic devices composed of reconfigurable arithmetic circuits and programmable coding metamaterials at terahertz frequencies, empowered by a diffractive optics platform using naturally extracted silk proteins, is reported. These protein‐based diffract optics are precisely manufactured into special microstructures for phase modulation of incident light and can be programmed to degrade at controlled rates. This allows spatial and temporal transformation of the incident light into desired intensity profiles to modulate the electrical properties of multiple photosensitive elements/components within the device simultaneously or discretely. Thus, the optoelectronic functionality of fabricated devices can be tailored to specific applications. Therefore, the approach makes it possible to efficiently fabricate tunable, reconfigurable transient electronic and photonic devices and systems.

Shaping Electric Field Intensity via Angular Spectrum Projection and the Linear Superposition Principle

Shaping the intensity distribution of radiated electromagnetic (EM) fields in a given bounded target area is a challenging problem in EMs. Although some approaches have been explored for this purpose, most are limited to the synthesis of plane-wave fields or point-focused fields. In this communication, a field-shaping method based on angular spectrum projection and the linear superposition principle is presented. The proposed method allows radiated electric fields to be shaped with different desired intensity patterns in a given limited target area with the use of the same antenna array. Via this method, all element excitations of the antenna array can be analytically calculated, and not only is the element excitation computational time reduced, but the real-time control of shaped fields is also made possible. Full-wave simulations were carried out to illustrate the 1-D and 2-D electric field shaping within a small given target area. In the 1-D case, three types of shaped fields with different desired distributions are demonstrated. In the 2-D case, three kinds of origin-symmetric shaped fields with different intensity distributions are illustrated. Finally, shaped fields with more complicated 2-D intensity distributions, like “I”- and “X”-shaped patterns, are demonstrated, and are achieved directly by applying the linear superposition principle to multiple point-focused fields with spatially overlapping focal spots.

Aerodynamic characteristics of variously modified leading-edge protuberanced (LEP) wind turbine blades under various turbulent intensities

A series of wind tunnel tests were performed to investigate the effect of turbulent inflows on the aerodynamic characteristics of variously modified leading-edge protuberanced (LEP) wing configurations at various turbulence intensities. A self-developed passive grid made of parallel arrays of round bars was placed at different locations of the wind tunnel to generate desired turbulence intensity. The aerodynamic forces acting over the baseline straight leading-edge model and the modified small, medium and high LEP wing configurations were obtained from the surface pressure measurements made over the wing at different turbulence intensities using MPS4264 Scanivalve simultaneous pressure scanner corresponding to a sampling frequency of 700Hz. All the test models were tested for a wide range of angles of attack ranging between −45° ≤ α ​≤ ​45° at turbulence intensities varying between 0.51% ​≤ ​TI ​≤ ​4.92%. Results reveal that the time-averaged mean coefficient of lift (CL) increases with the increase in the turbulence intensity associated with smooth stall characteristics rendering the modified LEP test models advantageous. Furthermore, based on the surface pressure coefficients the underlying dynamics behind the stall delay tendency were discussed. Additionally, attempts were made to statistically quantify the aerodynamic forces using standard deviation at both the pre-stall and the post-stall angles.

Wavefront shaping in multimode fibers by transmission matrix engineering

We present a new approach for shaping light at the output of a multimode fiber by modulating the transmission matrix of the system rather than the incident light. We apply computer-controlled mechanical perturbations to the fiber and obtain a desired intensity pattern at its output resulting from the changes to its transmission matrix. Using an all-fiber apparatus, we demonstrate focusing light at the distal end of the fiber and dynamic conversion between fiber modes in the few-mode regime. Since in this approach the number of available degrees of control scales with the number of spectral channels and can thus be larger than the number of fiber modes, it potentially opens the door to simultaneous control over multiple inputs and at multiple wavelengths.

Effects of Top-hat Laser Beam Processing and Scanning Strategies in Laser Micro-Structuring.

The uniform energy distribution of top-hat laser beams is a very attractive property that can offer some advantages compared to Gaussian beams. Especially, the desired intensity distribution can be achieved at the laser spot through energy redistribution across the beam spatial profile and, thus, to minimize and even eliminate some inherent shortcomings in laser micro-processing. This paper reports an empirical study that investigates the effects of top-hat beam processing in micro-structuring and compares the results with those obtainable with a conventional Gaussian beam. In particular, a refractive field mapping beam shaper was used to obtain a top-hat profile and the effects of different scanning strategies, pulse energy settings, and accumulated fluence, i.e., hatch and pulse distances, were investigated. In general, the top-hat laser processing led to improvements in surface and structuring quality. Especially, the taper angle was reduced while the surface roughness and edge definition were also improved compared to structures produced with Gaussian beams. A further decrease of the taper angle was achieved by combining hatching with some outlining beam passes. The scanning strategies with only outlining beam passes led to very high ablation rates but in expense of structuring quality. Improvements in surface roughness were obtained with a wide range of pulse energies and pulse and hatch distances when top-hat laser processing was used.

Enhancing Virtual Rehabilitation in Upper Limbs With Biocybernetic Adaptation: The Effects of Virtual Reality on Perceived Muscle Fatigue, Game Performance and User Experience

Virtual rehabilitation has been used during decades to provide a more personalized, controlled, and enjoyable experience on upper-limb motor rehabilitation. Since novel virtual reality (VR) technologies are now accessible and highly immersive, the challenge for a wide dissemination of virtual rehabilitation in clinical scenarios has shifted from the hardware robustness to the software intelligence. A sophisticated technique that provides physiological intelligence to novel human-computer interaction (HCI) applications is biocybernetic adaptation. The concept emerges from the electrophysiological computing field, and it proposes using body signals to detect human states (e.g. workload or fatigue) and modulate the virtual activity accordingly. This paper evaluates the effects of using biocybernetic adaptation in a virtual rehabilitation game that aims to encourage users to exert at a desirable intensity level while interacting with the virtual environment. The system relies on surface-electromyography (sEMG) signals to detect fatigue levels in real-time and adapt the game challenge dynamically. Perceived fatigue levels, game user experience, and game performance parameters are assessed after playing the game, considering two different visualization modalities: non-immersive (conventional flat screen) and immersive (VR headset). Results revealed how the biocybernetic system in the immersive condition not only produced lower levels of perceived fatigue compared with the non-immersive, but also, created a more enjoyable and positive experience in a controlled experiment with 24 healthy subjects. Moreover, participants in the immersive condition showed a better performance in the virtual game and higher usability levels scored by users compared with the non-immersive condition. To conclude, we highlight the importance of combining novel immersive approaches with physiologically aware systems to enhance the benefits of virtual rehabilitation therapies.