Study of Cu/SiO2/Cu Metamaterials: Design, Simulation, Fabrication, Testing, and Optical Applications

In the past few years, “metamaterials” have grabbed attention of researchers in both science and engineering. They have revealed great potentials to realize unusual optical applications such as flat lenses or frequency-selective performances with their unusual electromagnetic properties. In this project, Cu/SiO2/Cu metamaterials of diverse designs and parameters were studied towards discovering their unknown optical applications. From simulation work, it was found that some metamaterials exhibit a performance of a rectangle-shaped bandpass at optical frequencies. Their operational wavelength region can be adjusted by having a different scale of the structure or a different thickness of the constituent materials. This indicates that those metamaterials could be used instead of traditional optical filters. A few selected metamaterials were fabricated and tested for comparison with the simulation results

Optical Structures for Thermophotovoltaic Emitters: Power Generation from Waste Heat

Heat is an inevitable outcome in energy consumption processes, as more than 65% of input energy is wasted as heat. If we can generate electricity from waste heat, it will help minimize the needs for fossil fuels in power plants and can reduce carbon emissions. One way to generate power from heat is through the use of thermophotovoltaics (TPVs), where photons radiated from thermal emitters are converted into electricity. To optimize TPV performance, it is crucial to design emitters such that their emissivity spectrum matches their operating temperature. For example, higher emissivity is needed at shorter (longer) wavelengths at higher (lower) temperatures. Thus, having the ability to create wavelength-selective emitters can enable TPV applications for a wider range of temperatures. This research focuses on utilizing metamaterials (2D emitters) and planar thin films (1D emitters) to create those emitters. Simulation, fabrication, material property analysis, and radiation measurements were used to characterize the emitters. Based on simulation, metamaterial emitters exhibit engineerable emissivity due to various mechanisms of their optical resonance. Also, large-area fabrication of 1D emitters (78 cm2) was achieved owing to their simple structure, which is required to produce higher TPV power output. Incorporating the characteristics of emitters of each type, their advantages and challenges are discussed. Therefore, the comprehensive results of this research help realize practical implementation of TPV applications

Expanding Scanning Frequency Range of Josephson Parametric Amplifier Axion Haloscope Readout with Schottky Diode Bias Circuit

The axion search experiments in the microwave frequency range require high sensitive detectors with intrinsic noise close to quantum noise limit. Josephson parametric amplifiers (JPAs) are the most valuable candidates for the role of the first stage amplifier in the measurement circuit of the microwave frequency range, as they are well-known in superconducting quantum circuits readout. To increase the frequency range, a challenging scientific task involves implementing an assembly with parallel connection of several single JPAs, which requires matching the complex RF circuit at microwaves and ensuring proper DC flux bias. In this publication, we present a new DC flux bias setup based on a Schottky diode circuit for a JPA assembly consisting of two JPAs. We provide a detailed characterization of the diodes at cryogenic temperatures lower than 4 K. Specifically, we selected two RF Schottky diodes with desirable characteristics for the DC flux bias setup, and our results demonstrate that the Schottky diode circuit is a promising method for achieving proper DC flux bias in JPA assemblies.Comment: 7 pages, 6 image

Development of multi-target dsRNAs targeting PcNLP gene family to suppress Phytophthora capsici infection in Nicotiana benthamiana

Phytophthora capsici, which causes diseases in solanaceous crops, secretes necrosis and ethylene-inducing peptide 1-like proteins (NLPs) that induce plant defense responses and leaf necrosis. In this study, we used RNA interference (RNAi) technique, a proven strategy for crop protection and gene regulation in plants, to suppress P. capsici infection through the inhibition of PcNLPs. In the RNAi mechanism, Dicer processes double-stranded RNA (dsRNA) into smaller entities known as small interfering RNAs (siRNAs). These siRNAs subsequently integrate into the RNA-induced silencing complex to form sequence-specific base pairing with complementary regions of the target mRNA. This interaction effectively initiates the degradation process of the target mRNA. We designed and synthesized dsRNAs targeting the AIMY and GHRHDWE conserved motifs of PcNLP gene family, which are predicted to be key elements for the expression of NLPs and pathogen infection. After infiltration of dsRNAs targeting the motifs and inoculation with P. capsici, we confirmed a significant suppression of P. capsici infection and downregulation of the PcNLP gene family. These findings imply that the dsRNA-mediated RNAi technique holds potential for mitigating a wide range of pathogens, while simultaneously suppressing the expression of a particular gene family using dsRNA targeting functional conserved motifs in the gene family.This study was supported by the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MSIT) (No. 2021R1A5A1032428). This was also supported by a grant from the New breeding technologies development Program (Project No. RS-2022-RD009544), Rural Development Administration, Republic of Kore

WALLABY Pilot Survey: H I gas kinematics of galaxy pairs in cluster environment

We examine the H I gas kinematics of galaxy pairs in two clusters and a group using Australian Square Kilometre Array Pathfinder (ASKAP) WALLABY pilot survey observations. We compare the H I properties of galaxy pair candidates in the Hydra I and Norma clusters, and the NGC 4636 group, with those of non-paired control galaxies selected in the same fields. We perform H I profile decomposition of the sample galaxies using a tool, BAYGAUD, which allows us to deblend a line-of-sight velocity profile with an optimal number of Gaussian components. We construct H I superprofiles of the sample galaxies via stacking of their line profiles after aligning the central velocities. We fit a double Gaussian model to the superprofiles and classify them as kinematically narrow and broad components with respect to their velocity dispersions. Additionally, we investigate the gravitational instability of H I gas discs of the sample galaxies using Toomre Q parameters and H I morphological disturbances. We investigate the effect of the cluster environment on the H I properties of galaxy pairs by dividing the cluster environment into three subcluster regions (i.e. outskirts, infalling, and central regions). We find that the denser cluster environment (i.e. infalling and central regions) is likely to impact the H I gas properties of galaxies in a way of decreasing the amplitude of the kinematically narrow H I gas (⁠MHInarrow /MHItotal ⁠), and increasing the Toomre Q values of the infalling and central galaxies. This tendency is likely to be more enhanced for galaxy pairs in the cluster environment

Effects of Walking Promotion Using Smart Mobile Activity Meter on Changes in Metabolic Health

Background: Regular physical exercise can increase insulin sensitivity, improve good cholesterol levels, reduce body weight, and ameliorate cardiovascular risk factors. Over the past decade, e-health technologies using mobile applications were proven to be an effective delivery method for educational interventions. No e-health tools were designated specifically for patients with metabolic syndrome. Methods: Final analysis subjects were 7,234 as a result of excluding cases with missing values according to the variables used. We mediated the subjects to walk in advance, 3 months, and 6 months through smart mobile health care, and the level of improvement in the metabolic syndrome index was repeatedly measured. RM ANOVA & Path analysis & Sobel test was conducted to determine whether there was a mediating effect. Results: Subjects who practiced walking for up to 3 months tended to use smart mobile health care devices better for 6 months, and the walking practice rate increased. This confirmed that there was a significant partial mediating effect as a result of the Sobel test. after 6 months, WC and TG decrease. Conclusion: It was found that the more programs that provide advice and interventions on physical activity through smart mobile healthcare devices were used, the more helpful it was to promote walking exercise practice

WALLABY Pilot Survey: HI gas kinematics of galaxy pairs in cluster environment

We examine the H I gas kinematics of galaxy pairs in two clusters and a group using Australian Square Kilometre Array Pathfinder (ASKAP) WALLABY pilot survey observations. We compare the H I properties of galaxy pair candidates in the Hydra I and Norma clusters, and the NGC 4636 group, with those of non-paired control galaxies selected in the same fields. We perform H I profile decomposition of the sample galaxies using a tool, BAYGAUD which allows us to de-blend a line-of-sight velocity profile with an optimal number of Gaussian components. We construct H I super-profiles of the sample galaxies via stacking of their line profiles after aligning the central velocities. We fit a double Gaussian model to the super-profiles and classify them as kinematically narrow and broad components with respect to their velocity dispersions. Additionally, we investigate the gravitational instability of H I gas disks of the sample galaxies using Toomre Q parameters and H I morphological disturbances. We investigate the effect of the cluster environment on the H I properties of galaxy pairs by dividing the cluster environment into three subcluster regions (i.e., outskirts, infalling and central regions). We find that the denser cluster environment (i.e., infalling and central regions) is likely to impact the H I gas properties of galaxies in a way of decreasing the amplitude of the kinematically narrow H I gas (⁠MnarrowHI role= presentation style= box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; font-variant: inherit; font-stretch: inherit; line-height: normal; font-family: inherit; vertical-align: baseline; display: inline; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; position: relative; \u3eMHInarrowMnarrowHI/MtotalHI role= presentation style= box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; font-variant: inherit; font-stretch: inherit; line-height: normal; font-family: inherit; vertical-align: baseline; display: inline; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; position: relative; \u3eMHItotalMtotalHI⁠), and increasing the Toomre Q values of the infalling and central galaxies. This tendency is likely to be more enhanced for galaxy pairs in the cluster environment

25th annual computational neuroscience meeting: CNS-2016

The same neuron may play different functional roles in the neural circuits to which it belongs. For example, neurons in the Tritonia pedal ganglia may participate in variable phases of the swim motor rhythms [1]. While such neuronal functional variability is likely to play a major role the delivery of the functionality of neural systems, it is difficult to study it in most nervous systems. We work on the pyloric rhythm network of the crustacean stomatogastric ganglion (STG) [2]. Typically network models of the STG treat neurons of the same functional type as a single model neuron (e.g. PD neurons), assuming the same conductance parameters for these neurons and implying their synchronous firing [3, 4]. However, simultaneous recording of PD neurons shows differences between the timings of spikes of these neurons. This may indicate functional variability of these neurons. Here we modelled separately the two PD neurons of the STG in a multi-neuron model of the pyloric network. Our neuron models comply with known correlations between conductance parameters of ionic currents. Our results reproduce the experimental finding of increasing spike time distance between spikes originating from the two model PD neurons during their synchronised burst phase. The PD neuron with the larger calcium conductance generates its spikes before the other PD neuron. Larger potassium conductance values in the follower neuron imply longer delays between spikes, see Fig. 17.Neuromodulators change the conductance parameters of neurons and maintain the ratios of these parameters [5]. Our results show that such changes may shift the individual contribution of two PD neurons to the PD-phase of the pyloric rhythm altering their functionality within this rhythm. Our work paves the way towards an accessible experimental and computational framework for the analysis of the mechanisms and impact of functional variability of neurons within the neural circuits to which they belong

Polarization of Nonunifrom Plane Waves: Incidence from a Lossless to a Lossy Medium

A nonunifrom plane wave (NPW) can be created when a uniform plane wave is incident from a lossless medium to a lossy medium at an oblique angle. Although the propagation and energy loss directions of NPWs are well-discussed in the literature, a discussion on their polarization is hardly found. This work discusses the polarization of NPWs and find that their antitransverse field, the field parallel to the plane of incidence, becomes elliptically polarized. The zero-divergence restriction determines the rotation direction of the antitransverse polarization.</p