Search

Many images used in media and advertising employ visual metaphors that provide enjoyment and storytelling. This study employed an image perception questionnaire to evaluate high school students’ image preferences. The results revealed that among the adjectives provided by the researcher, high school students exhibited higher preferences for describing images as creative, symbolic, cultural, artistic, contrasting, serious, exaggerated, and rational imagery. According to the independent sample t-test results, a pronounced gender difference existed in the preference of selection from the ‘Conservative–Creative’ adjective pair to describe images. Additionally, male and female students displayed higher preferences for describing fusion metaphorical images as ‘natural’ and ‘cultural’, respectively. The preferences of students of different genders for metaphorical images were considerably influenced by the conservative, creative, natural, or cultural elements of the images. According to the results of the chi-square test of independence and phi correlation coefficient test, gender exhibited a significant but low correlation with students’ preferences for juxtaposed and replacement metaphorical images. The findings of this study can provide valuable insights for art educators to gain a deeper understanding of gender differences in students’ image assessments and preferences when viewing images, helping them select appropriate visual teaching materials.

Providing a safe and secure living environment for residents that is supported by a dedicated healthcare team is one of the core values of nursing homes. Nursing homes must protect residents from the risk of going missing, track quarantined residents and visitors to control the spread of infection, and maintain proactive nursing rounds. However, recruiting and retaining qualified caregivers and medical staff has long been a challenge. Therefore, using advanced technology to ensure the safety and security of residents is highly desirable. In this work, we first demonstrate the applicability of indoor tracking applications in a nursing home, such as resident and asset tracking, nursing assistant management, visitor tracking, infection control, and vital-sign monitoring. To monitor the locations of residents and staff, Bluetooth tags were used, providing real-time data for location tracking. We then conduct a series of quantitative analyses to illustrate how indoor tracking data can support the management of nursing homes, including characterizing residents’ activities in daily living and assessing the performance and workload of nursing assistants. Finally, we use qualitative research to evaluate the acceptability of an indoor positioning system in the nursing home. The results show that the implemented indoor positioning applications can improve the quality of healthcare and working efficiency, thereby providing a safer and more secure living environment for residents.

AbstractThis study combined the principles of multimedia message design with an enclosing-rectangle scaffold to facilitate instruction on deriving the area of basic geometric shapes. A pretest/posttest/delayed-posttest design was used to compare the effectiveness of the enclosing-rectangle scaffold with that of conventional dissection/rearrangement methods among low-achieving seventh-grade students. These fifty-six low-achieving students were averagely assigned to one of two teaching methods. In immediate and delayed testing, an enclosing-rectangle scaffold proved significantly more effective than the conventional approach (posttest: F (1,53) = 16.148, p =

Prolonged sitting with poor posture can lead to various health problems, including upper back pain, lower back pain, and cervical pain. Maintaining proper sitting posture is crucial for individuals while working or studying. Existing pressure sensor-based systems have been proposed to recognize sitting postures, but their accuracy ranges from 80% to 90%, leaving room for improvement. In this study, we developed a sitting posture recognition system called SPRS. We identified key areas on the chair surface that capture essential characteristics of sitting postures and employed diverse machine learning technologies to recognize ten common sitting postures. To evaluate the accuracy and usability of SPRS, we conducted a ten-minute sitting session with arbitrary postures involving 20 volunteers. The experimental results demonstrated that SPRS achieved an impressive accuracy rate of up to 99.1% in recognizing sitting postures. Additionally, we performed a usability survey using two standard questionnaires, the System Usability Scale (SUS) and the Questionnaire for User Interface Satisfaction (QUIS). The analysis of survey results indicated that SPRS is user-friendly, easy to use, and responsive.

This study demonstrates controllable random lasing emissions in a dye-doped nematic liquid crystal (DDNLC)-infiltrated microcapillary. The emission wavelength of the micro tube laser can be adjusted by changing the focusing position of the pumped pulses on the center or the periphery of the liquid crystal region of the microcapillary. In addition, with doping azo-dyes in the DDNLC of the micro tube laser, optical controllability of the lasing intensity and wavelength can be further achieved. The controllable micro tube laser may find highly widespread photonic applications in multicolor emitting sources, and vibration and UV sensors.

A terahertz metasurface that is imbedded into a dye-doped liquid crystal (DDLC) cell is fabricated in this work. After the metasurface-imbedded DDLC cell is irradiated with a linearly polarized pump beam, the irradiated cell is measured with a terahertz spectrometer. The irradiation of the pump beam causes the adsorption of the dye on one of the substrates of the cell, scattering incident terahertz waves and decreasing the transmittances of the terahertz metasurface at all the frequencies of its resonance spectrum. In addition, these transmittances decrease with an increase in the irradiation times of the pump beam. The adsorbed dye molecules are erased from the substrate after the cell is heated by a hot plate. The cell has similar spectra before the irradiation of the pump beam and after the heating of the hot plate. The aforementioned results reveal that the metasurface-imbedded DDLC cell is an optically tunable and thermally erasable terahertz intensity modulator. Therefore, this cell has the potential in developing intensity attenuators for terahertz imaging, frequency isolators for terahertz telecommunication, and spatial light modulators for terahertz information encryption and decryption.

An optically tunable terahertz filter was fabricated using a metasurface-imbedded liquid crystal (LC) cell with photoalignment layers in this work. The LC director in the cell is aligned by a pump beam and makes angles θ of 0, 30, 60 and 90° with respect to the gaps of the split-ring resonators (SRRs) of the metasurface under various polarized directions of the pump beam. Experimental results display that the resonance frequency of the metasurface in the cell increases with an increase in θ, and the cell has a frequency tuning region of 15 GHz. Simulated results reveal that the increase in the resonance frequency arises from the birefringence of the LC, and the LC has a birefringence of 0.13 in the terahertz region. The resonance frequency of the metasurface is shifted using the pump beam, so the metasurface-imbedded LC cell with the photoalignment layers is an optically tunable terahertz filter. The optically tunable terahertz filter is promising for applications in terahertz telecommunication, biosensing and terahertz imaging.

In this study, the all-optical control properties of photonic crystals based on self-assembled chiral-azobenzene-doped blue phase liquid crystals (CA-BPLCs) were investigated. The difference in the photothermal characteristics of CA-BPLCs with and without homogeneous surface alignment was discussed. Results revealed that surface alignment could induce more uniform and diverse blue phase (BP) structures, including BPII, BPI, and BPS-like phases during cooling. Consequently, the temperature range of BP was wider than that of the sample without surface alignment. All-optical control experiments with light illumination were then performed on the aligned or nonaligned CA-BPLC samples. During continuous irradiation with light beams at wavelengths of 405 and 450 nm, CA dopants underwent trans→cis and cis→trans back photoisomerizations, respectively. These processes promoted isothermal phase transition and wavelength shifting, which further enabled the all-optical control of the CA-BPLC samples. Various optical control modes of BPLC could be achieved through phase change and wavelength shifting by appropriately selecting the working temperature and surface treatment of BPLC. This study could be further used as a basis for developing photoswitchable and tunable BPLC photonic devices, such as light-controllable gratings, filters, mirrors, and lasers.

Refilling cholesteric liquid crystal (CLC) template gratings with circular polarization, wavelength selectivity, and dual operation mode are first demonstrated. The gratings with template and nontemplate regions are obtained through the two-beam interfering photo-polymerization, washing-out, and refilling procedure. The refilling CLC has different chiral handedness (left or right) and reflection band (at green and red regions). When the wavelength of a probe beam is within the refilled CLC reflection band of the nontemplate region, the device works as an amplitude grating since the sample in the template and nontemplate regions reflects distinct colour region. In addition, the diffraction intensity of the grating can be electrically controlled. Therefore, this CLC-based device can be potentially used in controllable diffraction elements in optics.

This work reports, for the first time, a dielectrophoresis (DEP) effect-induced motion of liquid crystal (LC) droplets in an LC/monomer mixture sample with a poly-(N-vinyl carbazole) PVK-coated substrate without an external voltage. With the UV pre-irradiation of the PVK layer through a binary mask, a laterally non-uniform electric field can be induced between the pre-illuminated regions and the neighboring non-pre-illuminated PVK regions near the borders of the two regions. The phase separation occurs once the temperature is lower than 50 °C and the LC droplets can form in the sample. The pre-formed non-uniform field provides a DEP-like force to manipulate the small LC microdroplets in the pre-illuminated regions to effectively migrate to the adjacent non-pre-illuminated regions. The continuous supply of the LC from the pre-illuminated regions to the adjacent non-pre-illuminated regions significantly increases the diffraction efficiency of the grating sample. This study provides an insight into developing new external-voltage-free DEP-based devices that can be applied on various fields, such as photonics, displays, and biomedicines.

This study demonstrates for the first time abnormal electro-optic (EO) characteristics induced by electrohydrodynamics (EHD) in a polymer-dispersed liquid crystal (PDLC) film in the presence of a low-frequency (1 kHz) AC voltage. Large LC droplets (20−40 µm) buried in the film can be obtained after the illumination of one UV light with a weak intensity (~0.96 mW/cm2) for 12 h. This film exhibits abnormal EO features, including the transmittance’s decay at a high voltage regime at normal incidence and the conversion between polarization independence and polarization dependence for the transmittance-voltage curve at normal and oblique incidences, respectively, of which properties are different from those shown in traditional PDLC films with small droplets. The abnormal EO characteristics of the large-droplet PDLC at the high voltage regime are attributed to a strong scattering effect associated with the formation of the foggy LC droplets in the cell. This effect is induced by a vortex-like LC director field with a rotational axis normal to the cell substrates in each dome-like droplet of the cell at the high voltage regime. The vortex-like director field is induced by a vortex-like turbulence of charged impurity generated by the EHD effect under the action of the AC electric field along the cell normal and the confinement of the dome-like boundary of the droplet on the charged impurities in each droplet. The scattering is decided by the degrees of mismatch between the refractive indices of the LC droplet and polymer, and the local fluctuation of the vortex-like director field in the droplet, resulting in the abnormal EO behaviors of the large-droplet PDLC. This investigation provides novel insight into the EHD effect in three dimensional (3D) microdroplets with anisotropic fluid. Such a large-droplet PDLC has potential in photonic applications, such as electrically controlled polarization-based optical components or optical converters between polarization independence and polarization dependence.