Compact pillbox reflector based on geodesic lens

We propose a pillbox antenna in combination with a geodesic lens at 60 GHz. The antenna is implemented in a dual-layer parallel plate waveguide. The waves from a geodesic lens in a first layer, after being reflected by a parabolic mirror connecting the rims of the two layers, enter a second layer and illuminate the radiation aperture. Since the lens produces a virtual focus, the reflector works as if it is fed from that a further location, making the system more compact.Project RTI2018-094475-B-I00 funded by MCIN/ AEI /10.13039/501100011033/ FEDER “Una manera de hacer Europa”. This article is based upon work from COST Action SyMat CA18223, supported by COST (European Cooperation in Science and Technology

Full-space metasurface at millimeter-wave frequencies

Conventional metasurfaces provide control over the electromagnetic waves in a single working frequency operating either in transmission or reflection. Full-Space Metasurfaces (FSM) are an extension that allows operation at two different frequencies with independent functionalities in transmission and reflection. This paper presents a gradient index FSM device based on a 3-layered unit cell where the phase modulation is implemented following the Pancharatman-Berry (PB) principle. The device is designed to operate at millimeter waves, with the lowest frequency operating in reflection and the highest one in transmission. To check the structure performance, a metasurface was designed to provide beam steering in reflection at 49.4 GHz and an amplitude image hologram in transmission at 104 GHz.This work was supported by MCIN/AEI/10.13039/ 501100011033/FEDER “Una manera de hacer Europa” via Project No. RTI2018-094475-B-I0

Design of multi-layered radiative cooling structures using evolutionary algorithms

In this work we present a novel way to design thinfilm radiative cooling metamaterials based on genetic algorithms. Three simulations with different design constraints have been done, resulting in three structures that achieve 39.96 W/m2 , 57.78 W/m2 and 61.77 W/m2 under direct sunlight, respectively. These structures are shorter than 5 µm of height and are composed of 9, 15 and 24 layers. This design method has the advantages of being automatable, needs fewer design experience in metamaterials and does not rely on commercial simulators. This work opens the path to an easy way of automated design of thin-film multi-layered devices for radiative cooling and other applications in the infrared range.This work has been performed in the frame of the project “Algoritmos EVOlutivos aplicados a dispositivos de enfriamiento radiativo pasivo ultracompactos basados en METAsuperficies” (AEVOMETA II), funded by the Government of Navarre

Metal-free design of a multilayered metamaterial with chirped Bragg grating for enhanced radiative cooling

A wideband, all-dielectric metamaterial structure for enhancing radiative cooling is investigated. The structure is optimized to reflect most of the solar irradiance window (between 0.3 µm–3 µm), which is one of the biggest challenges in highly efficient radiative cooling coatings. The design is based on the principles of Bragg gratings, which constitutes a simple synthesis procedure to make a broadband reflector of reduced dimensions, without metallic layers, while keeping a flat enough response in the entire bandwidth. Numerical results show that reflection of solar irradiation can be easily tailored and maximized using this method, as well as the net cooling power of the device, about ∼79 W/m2 at daytime (about double at night-time) and a temperature reduction of 23 K (assuming no heat exchange) and 7 K assuming a heat exchange coefficient of 10 W/m2/K, for a device and ambient temperatures of 300 K and 303 K, respectively. This occurs even in detriment of absorption in the atmospheric window (8 µm–13 µm). Results also show the importance of efficiently reflecting solar irradiance for such technologies and its relevance in synthesis and design without using metallic components.European Commission (Next Generation, PRTR, TED2021-132074B-C33); Ministerio de Ciencia e Innovación (TED2021-132074B-C33); Gobierno de Navarra (PC048-049-DisenIA)

Evolutionary algorithms applied to multi-layered radiative cooling metamaterials

A newly design method for designing multi-layered radiative cooling metamaterials based on genetic algorithms (GAs) is exposed. The developed GA has been tested in three cases, resulting in three different structures that achieve, theoretically under direct sunlight, a net cooling power of 39.96 W/m 2 , 57.78 W/m 2 and 61.77 W/m 2 . Such devices are composed of 9, 15 and 24 layers respectively with a total thickness of less than 4.8 µm in the worst case. By the nature of the method, fewer design experience in metamaterials is needed, as well as it is free-cost, due to the use of analytical calculations for the emissivity of the meta materials instead of a commercial generic electromagnetic solver. Automated design of radiative cooling multi-layered structures and other applications in the infrared range can be further developed with this work.This work has been performed in the frame of the project "Algoritmos EVOlutivos aplicados a dispositivos de enfriamiento radiativo pasivo ultracompactos basados en METAsuperficies (AEVOMETA II), funded by the Government of Navarre

Hyperbolic lens antenna in groove gap waveguide technology at sub-millimeter waves

In this paper, a flat hyperbolic lens antenna using Groove Gap Waveguide (GGW) technology is designed at 300 GHz. A GGW horn antenna is used to feed the metamaterial lens placed in a parallel plate waveguide (PPW), in order to increase the directivity in the direction of propagation. The combination of both devices, the metalens and the GGW antenna, achieves excellent radiation performance

Fully metallic Luneburg metalens antenna in gap waveguide technology at V-band

This article presents the design of a flat Luneburg metalens antenna at V-band using gap waveguide (GW) technology. The metalens consists of a parallel plate waveguide (PPW) loaded with metallic pins whose height is modulated to get an effective refractive index that follows the Luneburg equation. A Groove GW (GGW) H-plane horn is used to illuminate the metalens, such that the rays are collimated and a planar wavefront is generated in the direction of propagation. Since the structure at hand is planar, it can be efficiently integrated on flat surfaces. Moreover, the fully metallic structure is mechanically robust and presents lower losses than lenses including dielectric substrates. A prototype has been fabricated and tested, simulations and experimental results are in very good agreement. The metalens yields an input reflection coefficient (S11) below −10 dB from 45 to 70 GHz, whereas the −3 dB gain fractional bandwidth is 26.2% with respect to a center frequency of 60 GHz, with a peak of 22.5 dB at 61 GHz. These features make this design an interesting solution for millimeter-wave (MMW) applications.This work was supported in part by MCIN/AEI/ 10.13039/501100011033/FEDER “Una manera de hacer Europa” under Project RTI2018-094475-B-I00 and in part by the Spanish State Research Agency under Project PID2019-109984RBC43/AEI/10.13039/ 501100011033

Enhancing the infrared and visible emission properties of calcium silicate hydrate for radiative cooling using metamaterials

Two periodic structures composed of metal cylinders with different orientations are used to improve the solar reflection of calcium silicate hydrate (CSH) while maintaining its atmospheric emission. Interesting effects have been found when the distance between bars is small, suggesting that lattice effects, arising from the interaction between the rods could be leveraged in the design of these metamaterials. The size of the metal bars is selected based on state of the art micro-manufacturing techniques. This study limits its scope to a CSH gel model; i.e. the most important component of cement-based materials. Further research will be undertaken to consider a best description of the dielectric function of concrete.This work has been funded by the research and innovation program Horizon 2020 of the European union. Project MIRACLE, Grant Agreement 964450

妊娠ラットとその胎仔のトリプトファン代謝 ～子宮内胎児発育不全（IUGR）の影響～

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Development of a Decision Aid for Career Choices after undergraduate and graduate students in nursing programs at the university

近年の看護系大学卒業・大学院修了後の就職に関する状況調査では，学生がやりたい看護についての 自分の意見がない，志望動機が病院とマッチしていない等の結果が報告されている。これらは，看護系 大学卒業・大学院修了を控えた学生が，自分の価値観にあった進路選択が行えていない可能性を示唆し ている。学生が，自分の進路について自己の特性を踏まえた上でやりたいことに向き合い，納得した進 路決定のための自律的な活動をサポートする必要性が高いと考える。学生にとっての進路選択の意思決 定は，難しい意思決定の1 つと考えられる。「オタワ意思決定ガイド（個人用）」は，このような難しい 判断や健康関連・社会的意思決定のために設計され，意思決定理論に基づき開発されている。このガイ ドを活用することで，学生の進路選択の意思決定をサポートすることができるのではないかと考えた。 本稿では，聖路加国際大学の学部生・学士編入生，大学院生の進路選択の支援のためのディシジョンエ イド開発のプロセスを報告する。departmental bulletin pape