High-security learning-based optical encryption assisted by disordered metasurface.

Artificial intelligence has gained significant attention for exploiting optical scattering for optical encryption. Conventional scattering media are inevitably influenced by instability or perturbations, and hence unsuitable for long-term scenarios. Additionally, the plaintext can be easily compromised due to the single channel within the medium and one-to-one mapping between input and output. To mitigate these issues, a stable spin-multiplexing disordered metasurface (DM) with numerous polarized transmission channels serves as the scattering medium, and a double-secure procedure with superposition of plaintext and security key achieves two-to-one mapping between input and output. In attack analysis, when the ciphertext, security key, and incident polarization are all correct, the plaintext can be decrypted. This system demonstrates excellent decryption efficiency over extended periods in noisy environments. The DM, functioning as an ultra-stable and active speckle generator, coupled with the double-secure approach, creates a highly secure speckle-based cryptosystem with immense potentials for practical applications.

Asymmetric Full-Color Vectorial Meta-holograms Empowered by Pairs of Exceptional Points.

Holography holds tremendous promise in applications such as immersive virtual reality and optical communications. With the emergence of optical metasurfaces, planar optical components that have the remarkable ability to precisely manipulate the amplitude, phase, and polarization of light on the subwavelength scale have expanded the potential applications of holography. However, the realization of metasurface-based full-color vectorial holography remains particularly challenging. Here, we report a general approach utilizing a modified Gerchberg-Saxton algorithm to achieve spatially aligned full-color display and incorporating wavelength information with an image compensation strategy. We combine the Pancharatnam-Berry phase and pairs of exceptional points to address the issue of redundant twin images that generally appear for the two orthogonal circular polarizations and to enable full polarization control of the vectorial field. Our results enable the realization of an asymmetric full-color vectorial meta-hologram, paving the way for the development of full-color display, complex beam generation, and secure data storage applications.

Creating pairs of exceptional points for arbitrary polarization control: asymmetric vectorial wavefront modulation.

Exceptional points (EPs) can achieve intriguing asymmetric control in non-Hermitian systems due to the degeneracy of eigenstates. Here, we present a general method that extends this specific asymmetric response of EP photonic systems to address any arbitrary fully-polarized light. By rotating the meta-structures at EP, Pancharatnam-Berry (PB) phase can be exclusively encoded on one of the circular polarization-conversion channels. To address any arbitrary wavefront, we superpose the optical signals originating from two orthogonally polarized -yet degenerate- EP eigenmodes. The construction of such orthogonal EP eigenstates pairs is achieved by applying mirror-symmetry to the nanostructure geometry flipping thereby the EP eigenmode handedness from left to right circular polarization. Non-Hermitian reflective PB metasurfaces designed using such EP superposition enable arbitrary, yet unidirectional, vectorial wavefront shaping devices. Our results open new avenues for topological wave control and illustrate the capabilities of topological photonics to distinctively operate on arbitrary polarization-state with enhanced performances.

Varifocal Metalenses: Harnessing Polarization-Dependent Superposition for Continuous Focal Length Control.

Traditional varifocal lenses are bulky and mechanically complex. Emerging active metalenses promise compactness and design flexibility but face issues like mechanical tuning reliability and nonlinear focal length tuning due to additional medium requirements. In this work, we propose a varifocal metalens design based on superimposing light intensity distributions from two orthogonal polarization states. This approach enables continuous and precise focal length control within the visible spectrum, while maintaining relatively high focusing efficiencies (∼41% in simulation and ∼28% in measurement) and quality. In experimental validation, the metalens exhibited flexible tunability, with the focal length continuously adjustable between two spatial positions upon variation of the incident polarization angle. The MTF results showed high contrast reproduction and sharp imaging, with a Strehl ratio of >0.7 for all polarization angles. With compactness, design flexibility, and high focusing quality, the proposed varifocal metalens holds potential for diverse applications, advancing adaptive and versatile optical devices.

High-Resolution Metalens Imaging with Sequential Artificial Intelligence Models.

An analysis of the optical response of a GaN-based metalens was conducted alongside the utilization of two sequential artificial intelligence (AI) models in addressing the occasional issues of blurriness and color cast in captured images. The optical loss of the metalens in the blue spectral range was found to have resulted in the color cast of images. Autoencoder and CodeFormer sequential models were employed in order to correct the color cast and reconstruct image details, respectively. Said sequential models successfully addressed the color cast and reconstructed details for all of the allocated face image categories. Subsequently, the CIE 1931 chromaticity diagrams and peak signal-to-noise ratio analysis provided numerical evidence of the AI models' effectiveness in image reconstruction. Furthermore, the AI models can still repair the image without blue information. Overall, the integration of metalens and artificial intelligence models marks a breakthrough in enhancing the performance of full-color metalens-based imaging systems.

Why Do Bystanders Become Cyberbullies? The Effect of Perceived Reasonableness of Online Messages on Bystanders' Aggressive Tendency and Its Underlying Mechanism.

The objectives of this study were to examine the influence of bystanders' perceived reasonableness of online messages on their aggressive tendency toward victims and to examine the mediating role of bystanders' attribution of responsibility to victims on their aggressive tendency toward the victims. Our study involved two parts: In Study 1, 295 Taiwanese undergraduates were recruited, and questionnaires were distributed to them to measure their perceived reasonableness of cyberbullying attacks. In Study 2, a total of 78 university students were recruited. The participants' perceived reasonableness of cyberbullying attacks was reduced through experimental manipulation. Subsequently, they were randomly assigned to a group with relatively low reasonableness or a control group. The results of both studies revealed that the participants' aggressive tendency toward the victim was influenced by their perceived reasonableness of cyberbully messages. The relation between perceived reasonableness and aggressive tendency was mediated by the participants' attribution of responsibility to the victim.

Measuring Cognitive and Social Interactive Attributes of Digital Natives: Development and Validation of a Scale.

Scholars refer to individuals who have been immersed in digital environments and who make easy use of digital languages to interact with the world as "digital natives," and Teo proposed four attributes of digital natives to illustrate their behavioral tendencies. We aimed to expand Teo's framework and to develop and validate the Scale of Digital Native Attributes (SDNA) for measuring cognitive and social interactive attributes of digital natives. Based on pre-test results, we retained 10 attributes and 37 SDNA items, with 3-4 items in each sub-dimension. We then recruited 887 Taiwanese undergraduates as respondents and conducted confirmatory factor analysis to establish construct validity. Moreover, the SDNA correlated with several other related measurements to demonstrate satisfactory criterion-related validity. Internal consistency was evaluated by McDonald's Omega (ω) and Cronbach's α coefficient, showing satisfactory reliability. This preliminary tool is now ready for cross validation and temporal reliability testing in further research.

High-frequency ultrasound imaging for monitoring the function of meningeal lymphatic system in mice.

The meningeal lymphatic system drains the cerebrospinal fluid from the subarachnoid space to the cervical lymphatic system, primarily to the deep cervical lymph nodes. Perturbations of the meningeal lymphatic system have been linked to various neurologic disorders. A method to specifically monitor the flow of meningeal lymphatic system in real time is unavailable. In the present study, we adopted the high-frequency ultrasound (HFUS) with 1,1'diocatadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI)-loaded microbubble and FePt@PLGA nanoparticle contrast agents to evaluate the flow of the meningeal lymphatic system in 2-month-old mice. Statistical analysis was performed to identify changes of HFUS signals among the microbubbles, FePt@PLGA nanoparticles, and saline control groups. Approximately 15 min from the start of intracerebroventricular injection of contrast agents, their signals were evident at the deep cervical lymph nodes and lasted for at least 60 min. These signals were validated on the basis of the presence of DiI and Fe signals in the deep cervical lymph nodes. Ligation of afferent lymphatic vessels to the deep cervical lymph nodes eliminated the HFUS signals. Moreover, ablation of lymphatic vessels near the confluence of sinuses decreased the HFUS signals in the deep cervical lymph nodes. Glioma-bearing mice that exhibited reduced lymphatic vessel immunostaining signals near the confluence of sinuses had lowered HFUS signals in the deep cervical lymph nodes within 60 min. The proposed method provides a minimally invasive approach to monitor the qualities of the meningeal lymphatic system in real time as well as the progression of the meningeal lymphatic system in various brain disease animal models.

Enhanced photoluminescence and shortened lifetime of DCJTB by photoinduced metal deposition on a ferroelectric lithography substrate.

The photodeposition of metallic nanostructures onto ferroelectric surfaces could enable new applications based on the assembly of molecules and patterning local surface reactivity by enhancing surface field intensity. DCJTB (4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran) is an excellent fluorescent dye and dopant material with a high quantum efficiency used for OLED displays on the market. However, how to raise the photoluminescence (PL) and reduce the lifetime of DCJTB in a substrate remain extraordinary challenges for its application. Here, we demonstrate a tunable ferroelectric lithography plasmon-enhanced substrate to generate photo-reduced silver nanoparticles (AgNPs) and achieve enhanced PL with a shortened lifetime depending on the substrate's annealing time. The enhanced PL with shortened lifetimes can attribute to the localized electromagnetic (EM) wave produced by the nanotextured AgNPs layers' surface and gap plasmon resonances. The simulation is based on the three-dimensional finite element method to explain the mechanism of experimental results. Since the absorption increases, the remarkable enhanced PL of DCJTB can attain in the fabricated periodically proton exchanged (PPE) lithium niobate (LiNbO3) substrate. Furthermore, the proposed fabrication method demonstrates to help tune the surface EM wave distribution in the substrate, which can simultaneously achieve the significantly shortened lifetime and high PL intensity of DCJTB in the substrate. Compared with the un-annealed substrate, the PL intensity of DCJTB in the assembly metallic nanostructures is enhanced 13.70 times, and the PL's lifetime is reduced by 12.50%, respectively. Thus, the fabricated substrate can be a promising candidate, verifying chemically patterned ferroelectrics' satisfaction as a PL-active substrate.

Effects of Attribute Affirmation and Achievement Goals on High School Students' Motivation.

Researchers have suggested that receiving attribute affirmation (AA) may increase the motivation of students to confront a challenge. However, we posited that to determine whether AA increases the motivation of students to confront a challenging task, we must consider dispositional achievement goals of the students. The participants were 171 junior-high-school students, randomly assigned to an AA or no affirmation condition. The results showed that AA enhanced the tendency to confront a challenging task for students who endorsed low mastery-approach goals (MAGs) and low performance-approach goals (PAGs) simultaneously (b = 0.5, p = 0.015). The effect was mainly mediated by the increasing state performance-approach goals (SPAGs) in confronting the task (indirect effect = 0.21, 95% CI = 0.04-0.49); however, being attribute-affirmed decreased the tendency to confront the challenging task for students adopting a dominant PAG orientation (b = -0.76, p = 0.049). In addition, for students adopting a dominant MAG orientation or adopting high MAGs and high PAGs simultaneously, no difference was noted in the tendency to confront the task between participants in the control and attribute-affirmed conditions.

Contingencies of Self-Worth on Positive and Negative Events and Their Relationships to Depression.

Previous studies have found that the relationship between contingencies of self-worth (CSW) and depression was generally weak. We posited that this is partly because previous studies assumed CSW on positive and negative events as the same construct (one-dimensional CSW), which should be better conceptualized as two distinctive dimensions (two-dimensional CSW) in explaining depression. A total of 393 undergraduates from Taiwan completed the measures regarding one-dimensional CSW, two-dimensional CSW, and depression. After dividing CSW of seven classic domains into two dimensions of positive and negative CSW, the results of confirmatory factor analyses showed that the two-dimensional CSW model had better model fit than the one-dimensional model in all domains. Furthermore, relative to using one-dimensional CSW as a predictor of depression, the variance accounted for largely increased when positive and negative CSW entered simultaneously in the regression equation. The results suggest that CSW on positive and negative events should be seen as two dimensions and this perspective may largely increase the explanatory power of CSW in explaining mental health.

Do incompatible arguments cause extensive processing in the evaluation of arguments? The role of congruence between argument compatibility and argument quality.

Previous studies have demonstrated that arguments incompatible with prior beliefs are subjected to more extensive refutational processing, scrutinized longer, and judged to be weaker than arguments compatible with prior beliefs. However, this study suggests whether extensive processing is implemented when evaluating arguments is not decided by argument compatibility, but by congruence between two evaluating tendencies elicited by both argument compatibility and argument quality. Consistent with this perspective, the results of two experiments show that relative to congruent arguments, participants judged arguments eliciting incongruent evaluating tendencies as less extreme in strength, spent more time, and felt more hesitant generating strength judgments for them. The results also show that it is mainly incongruent arguments, not congruent arguments, whose strength ratings were more closely associated with the perceived personal importance of the issue, which intensified the tendency to evaluate arguments depending on argument compatibility. These results suggest that it is the incongruity between argument compatibility and argument quality, and not simply the argument compatibility, that plays a more important role in activating an extensive processing in the evaluation of arguments.

Vibronic and cation spectroscopy of 2,4-difluoroaniline.

We applied the two-color resonant two-photon ionization and mass-analyzed threshold ionization techniques to record the vibronic and cation spectra of 2,4-difluoroaniline. The cation spectra were recorded by ionizing via the 0(0), X(1), 6b(1), and 1(1) levels of the electronically excited S(1) state. Most of the observed active modes of this molecule in the S(1) and cationic ground D(0) states are related to the in-plane ring deformation vibrations. The band origin of the S(1)←S(0) electronic excitation was found to appear at 33294 ± 2 cm(-1), whereas the adiabatic ionization energy was determined to be 63935 ± 5 cm(-1). Comparing the data of 2,4-difluoroaniline with those of aniline, 2-fluoroaniline, and 4-fluoroaniline, one can learn the effects of fluorine substitution on the electronic transition and molecular vibration.