Children’s Health, Parent-Child Activities, Using Digital Devices, and Social Competence: Serial Mediation

Background: Studies have pointed out the influence of different children’s activities and prolonged use of digital products on their social development. However, whether the parent-child activities and using digital devices were serial mediators of the relationship between children’s health and social development needs further verification. Purpose: This study explored how parent-child activities and children’s use of digital devices influence the relationship between children’s health and their social competence. Method: This study used data from Kids in Taiwan: National Longitudinal Study of Child Development and Care. A total sample of 2164 participants was used in this study. Serial mediation analyses were performed using model six of Hayes’ PROCESS (2012). Results: This study found that parent-child activities and the use of digital devices can serially mediate the relationship between children’s health and social competence. Children’s health could directly improve their social competence, but it could also serially mediate social competence by increasing parent-child activities and reducing the use of digital devices. Conclusion: Childcare policy planners and parenting educators should not only call on parents to reduce the use of electronic products for their children, but also encourage parents to spend more time interacting with their children, so that children can learn social skills by interacting with others in their daily lives.

Estimation-free spatial-domain image reconstruction of structured illumination microscopy

Structured illumination microscopy(SIM)achieves super-resolution(SR)by modulating the high-frequency information of the sample into the passband of the optical system and subsequent image reconstruction.The traditional Wiener-filtering-based reconstruction algorithm operates in the Fourier domain,it requires prior knowledge of the sinusoidal illumination patterns which makes the time-consuming procedure of parameter estimation to raw datasets necessary,besides,the parameter estimation is sensitive to noise or aberration-induced pattern distortion which leads to reconstruction artifacts.Here,we propose a spatial-domain image reconstruction method that does not require parameter estimation but calculates patterns from raw datasets,and a reconstructed image can be obtained just by calculating the spatial covariance of differential calculated patterns and differential filtered datasets(the notch filtering operation is performed to the raw datasets for attenuating and compensating the optical transfer function(OTF)).Experiments on reconstructing raw datasets including nonbiological,biological,and simulated samples demonstrate that our method has SR capability,high reconstruction speed,and high robustness to aberration and noise.

Professional caregivers’ perceptions on the prerequisites for and consequences of people with mild dementia using a digital photo diary

Research is currently ongoing to investigate the use of assistive technology by people with mild dementia to support independent living at home. The aim of this study was to describe professional caregivers’ perceptions on the prerequisites for and consequences of people with mild dementia using a digital photo diary to facilitate their talks about daily events with their family members. A questionnaire was sent out to 582 participants (response rate 70.1%) to elucidate the professional caregivers’ perceptions on the use of the digital photo diary. The questionnaire contained both quantitative and qualitative data and was analyzed with descriptive statistics, factor analysis, multivariate analysis of covariance and qualitative content analysis. This study reports the results related to prerequisites and consequences of using the photo diary. The results from the factor analysis revealed four factors: Trust, Vulnerability, Dependency/Independency and Control. The qualitative content analysis resulted in five categories: Immediate implementation after receiving a diagnose is required, Relatives’ participation is a necessity, Strengthened self-esteem and meaningful everyday life, Increased alienation and a feeling of isolation and Assistive digital devices provide opportunities. The theme was interpreted as: Personalization and the preservation of dignity. The conclusion that can be drawn from this study is that the participants had an overall positive view of the usage of this specific digital photo diary for people suffering from dementia, but rigorous considerations needs before implementation of the device and regularly follow ups if dignity is to be maintained for people with dementia.

Dynamic full-color digital holographic 3D display on single DMD

Digital holography has high potentials for future 3D imaging and display technology.We present a method for a dynamic full-color digital holographic 3D display on single digital micro-mirror device(DMD)with full-color,high-speed and high-fidelity characteristics.We combine the square regions of adjacent micro-mirrors into super-pixels that can modulate amplitude and phase independently.Gray images are achieved by amplitude modulation and precise positioning of each color is achieved by phase modulation.The proposed method realizes a full-color imaging based on the three primary colors and achieves measured structural similarity of more than 88%and color similarity of more than 98%,while retaining the high switch speed of 9 kHz,thus achieving dynamic full-color 3D display on charge-coupled device(CCD).

Superpixel-Based Complex Field Modulation Using a Digital Micromirror Device for Focusing Light through Scattering Media

We present a digital micromirror device（DMD） based superpixel method for focusing light through scattering media by modulating the complex field of incident light. Firstly, we numerically and experimentally investigate focusing light through a scattering sample using the superpixel methods with different target complex fields.Then, single-point and multiple-point focusing experiments are performed using this superpixel-based complex modulation method. In our experiment, up to 71.5% relative enhancement is realized. The use of the DMDbased superpixel method for the control of the complex field of incident light opens an avenue to improve the enhancement of focusing light through scattering media.

Fringe optimization for structured illumination super-resolution microscope with digital micromirror device

Structured illumination microscopy(SIM)is a promising super-resolution technique for imaging subcellular structures and dynamics due to its compatibility with most commonly usedffuorescent labeling methods.Structured illumination can be obtained by either laser interference or projection of fringe patterns.Here,we proposed a fringe projector composed of a compact multiwavelength LEDs module and a digital micromirror device(DMD)which can be directly attached to most commercial invertedffuorescent microscopes and update it into a SIM system.The effects of the period and duty cycle of fringe patterns on the modulation depth of the structured lightfield were studied.With the optimized fringe pattern,1:6×resolution improvement could be obtained with high-end oil objectives.Multicolor imaging and dynamics of subcellular organelles in live cells were also demonstrated.Our method provides a low-cost solution for SIM setup to expand its wide range of applications to most research labs in thefield of life science and medicine.

Arbitrary amplitude femtosecond pulse shaping via a digital micromirror device

An ultrafast spectrum programmable femtosecond laser may enhance the performance of a wide variety of scientific applications,e.g.,multi-photon imaging.In this paper,we report a digital micromirror device(DMD)-based ultrafast pulse shaper,i.e.,DUPS,for femtosecond laser arbitrary amplitude shaping-the first time a programmable binary device reported to shape the amplitudes of ultrafast pulses spectrum at up to 32 kHz rate over a broad wavelength range.The DUPS is highly effcient,compact,and low cost based on the use of a DMD in combination with a transmission grating.Spatial and temporal dispersion introduced by the DUPS is compensated by a quasi-4-f setup and a grating pair,respectively.Femtosecond pulses with arbitrary spectrum shapes,including rectangular,sawtooth,triangular,double-pulse,and exponential profile,have been demonstrated in our experiments.A feedback operation process is implemented in the DUPS to ensure a robust and repeatable shaping process.The total effciency of the DUPS for amplitude shaping is measured to be 27%.

digital micromirror device;flat-top beam;orbital angular momentum;perfect vortex beam;random fiber laser

High-intensity vortex beams with tunable topological charges and low coherence are highly demanded in applications such as inertial confinement fusion(ICF) and optical communication. However, traditional optical vortices featuring nonuniform intensity distributions are dramatically restricted in application scenarios that require a high-intensity vortex beam owing to their ineffective amplification resulting from the intensity-dependent nonlinear effect. Here, a low-coherence perfect vortex beam(PVB) with a topological charge as high as 140 is realized based on the super-pixel wavefront-shaping technique. More importantly, a globally adaptive feedback algorithm(GAFA) is proposed to efficiently suppress the original intensity fluctuation and achieve a flat-top PVB with dramatically reduced beam speckle contrast. The GAFA-based flat-top PVB generation method can pave the way for high-intensity vortex beam generation,which is crucial for potential applications in ICF, laser processing, optical communication and optical trapping.

Inverse design of digital nanophotonic devices using the adjoint method

A high-efficiency inverse design of"digital"subwavelength nanophotonic devices using the adjoint method is proposed.We design a single-mode 3dB power divider and a dual-mode demultiplexer to demonstrate the efficiency of the proposed inverse design approach,called the digitized adjoint method,for single-and dual-object optimization,respectively.The optimization comprises three stages:1)continuous variation for an"analog"pattern;2)forced permittivity biasing for a"quasi-digital"pattern;and 3)a multilevel digital pattern.Compared with the conventional brute-force method,the proposed method can improve design efficiency by about five times,and the performance optimization can reach approximately the same level.The method takes advantages of adjoint sensitivity analysis and digital subwavelength structure and creates a new way for the efficient and high-performance design of compact digital subwavelength nanophotonic devices,which could overcome the efficiency bottleneck of the brute-force method,which is restricted by the number of pixels of a digital pattern,and improve the device performance by extending a conventional binary pattern to a multilevel one.

Generation and Display System of Measurement Matrix Based on DMD

A measurement matrix is the key to sampling and signal reconstruction during the process of compressed sensing.On the basis of digital light processing(DLP)technology,ageneration and display system of measurement matrix based on digital micro-mirror device(DMD)is proposed and well designed.In this system,the generation and controlling of measurement matrix are implemented on a PC,which reduces the hardware requirement to generate a random matrix and overcomes the difficulty of the hardware implementation for the random matrix.It can set up the display number of the measurement matrix,the mode of display and display time according to the requirements from users.The display information can be designed to complete the display of measurement matrix with a better adaptability.The system can be easily embedded into a variety of compressed sensing applications,which can be used to generate and display the corresponding measurement matrice with strong portability.In addition,the DMD of this system will be used as a spatial optical modulator to manipulate near-infrared light in a fast,accurate and efficient way in several applications such as in 3D scanning devices and spectrometers.

Hiding an image in cascaded Fresnel digital holograms

A system of two separated computer-generated holograms termed cascaded Fresnel digital holography （CFDH） is proposed and its application to hiding information is demonstrated by a computer simulation experiment. The technique is that the reconstructed image is the result of the wave Fresnel diffraction of two sub-holograms located at different distances from the imaging plane along the illuminating beam. The two sub-holograms are generated by an iterative algorithm based on the projection onto convex sets. In the application to the hiding of optical information, the information to be hidden is encoded into the sub-hologram which is multiplied by the host image in the input plane, the other sub-hologram in the filter plane is used for the deciphering key, the hidden image can be reconstructed in the imaging plane of the CFDH setup.

Dynamic infrared scene simulation using grayscale modulation of digital micro-mirror device

Dynamic infrared scene simulation is for discovering and solving the problems encountered in designing, developing and manufacturing infrared imaging guidance weapons. The infrared scene simulation is explored by using the digital grayscale modulation method. The infrared image modulation model of a digital micro-mirror device （DMD） is established and then the infrared scene simulator prototype which is based on DMD grayscale modulation is developed. To evaluate its main parameters such as resolution, contrast, minimum temperature difference, gray scale, various DMD subsystems such as signal decoding, image normalization, synchronization drive, pulse width modulation （PWM） and DMD chips are designed. The infrared scene simulator is tested on a certain infrared missile seeker. The test results show preliminarily that the infrared scene simulator has high gray scale, small geometrical distortion and highly resolvable imaging resolution and contrast and yields high-fidelity images, thus being able to meet the requirements for the infrared scene simulation inside a laboratory.

Adaptive suppression of passive intermodulation in digital satellite transceivers

For the performance issues of satellite transceivers suffering passive intermodulation interference,a novel and effective digital suppression algorithm is presented in this paper.In contrast to analog approaches,digital passive intermodulation（PIM） suppression approaches can be easily reconfigured and therefore are highly attractive for future satellite communication systems.A simplified model of nonlinear distortion from passive microwave devices is established in consideration of the memory effect.The multiple high-order PIM products falling into the receiving band can be described as a bilinear predictor function.A suppression algorithm based on a bilinear polynomial decorrelated adaptive filter is proposed for baseband digital signal processing.In consideration of the time-varying characteristics of passive intermodulation,this algorithm can achieve the rapidness of online interference estimation and low complexity with less consumption of resources.Numerical simulation results show that the algorithm can effectively compensate the passive intermodulation interference,and achieve a high signal-to-interference ratio gain.

High-speed playback of spatiotemporal division multiplexing holographic 3D video stored in a solid-state drive using a digital micromirror device

We propose a high-speed playback method for the spatiotemporal division multiplexing electroholographic three-dimensional(3D)video stored in a solid-state drive(SSD)using a digital micromirror device.The spatiotemporal division multiplexing electroholography prevents deterioration in the reconstructed 3D video from a 3D object comprising many object points.In the proposed method,the stored data is remarkably reduced using the packing technique,and the computer-generated holograms are played back at high speed.Consequently,we successfully reconstructed a clear 3D video of a 3D object comprising approximately 1,100,000 points at 60 frames per second by reducing the reading time of the stored data from an SSD.

Compressed sensing reconstruction of sparse spectrum based on digital micro-mirror device platform

A new method which employs compressive sensing(CS) to reconstruct the sparse spectrum is designed and experimentally demonstrated. On the basis of CS theory, the simulation results indicate that the probability of reconstruction is high when the step of the sparsity adaptive matching pursuit algorithm is confirmed as 1. Contrastive analysis for four kinds of commonly used measurement matrices: part Hadamard, Bernoulli, Toeplitz and Circular matrix, has been conducted. The results illustrate that the part Hadamard matrix has better performance of reconstruction than the other matrices. The experimental system of the spectral compression reconstruction is mainly based on the digital micro-mirror device(DMD). The experimental results prove that CS can reconstruct sparse spectrum well under the condition of 50% sampling rate. The system error 0.0781 is obtained, which is defined by the average value of the 2-norm. Furthermore, the proposed method shows a dominant ability to discard redundancy.

Improving seeking precision by utilizing ghost imaging in a semi-active quadrant detection seeker

Conventional semi-active laser guidance takes advantage of the laser designator to illuminate the stable and uniform laser spot on target precisely.The seeker collects the reflected light by a quadrant detector and outputs the relative position information to guide the missile to the illuminating laser spot.However,the designation and guidance accuracy could be jeopardized by the randomly drifting of laser spot caused by the instability of designation platform and air turbulence.In this work,ghost imaging technique is adapted to a quadrant detector semi-active seeker by utilizing structured illumination on the target.With a series of structured illumination masks,the signals from the quadrant detector are multiplexed to perform calculation of the target relative position as well as image reconstruction of the illuminated area simultaneously.Automatic target recognition methods could be further applied to the reconstructed image to calculate the designating error and correct the guidance.The results of simulation and experiment demonstrate that the proposed method could improve the guidance accuracy in many circumstances which would lead to attacking deviation if conventional semi-active laser guidance is used.

Real-time gradation-expressible amplitude-modulationtype electroholography based on binary-weighted computer-generated hologram

In amplitude-modulation-type electroholography, the binary-weighted computer-generated hologram(BW-CGH) facilitates the gradation-expressible reconstruction of three-dimensional(3 D) objects. To realize real-time gradation-expressible electroholography, we propose an efficient and high-speed method for calculating bit planes consisting of BW-CGHs. The proposed method is implemented on a multiple graphics processing unit(GPU) cluster system comprising 13 GPUs. The proposed BW-CGH method realizes eight-gradation-expressible electroholography at approximately the same calculation speed as that of conventional electroholography based on binary computer-generated holograms. Consequently, we were able to successfully reconstruct a real-time electroholographic 3 D video comprising approximately 180,000 points expressed in eight gradations at 30 frames per second.