Extractive foraging is considered a key selective pressure for the evolution of primate cognitive abilities—the extractive foraging hypothesis. Although tool‐use and substrate‐use are representatives ...of the foraging strategy, some primates engage in extractive foraging without external objects. Manual processing skills of prickly foods have been described in some species, whereas there are few studies on other type of food defenses. Here, I describe extractive foraging of hard‐shelled walnuts by wild Japanese macaques (Macaca fuscata), focusing on whether they accomplish the tasks only by their physical strength or require manual and/or oral processing skills to crack open the walnut shells. The study subjects comprised all members of troop B1 and three nontroop males in Kinkazan Island, Japan. Walnut feeding was observed during the main walnut seasons (September–December) when the troop visited walnut patches for 79 days in 2 years. I categorized the walnut feeding behavior into complete cracking and partial cracking. The number of times the five behavioral elements in the cracking stage occurred were counted from complete cracking. All six adult males and 11 of the 17 adult/adolescent females showed complete cracking, while the remaining females were never observed exhibiting this activity, despite their physical maturity. I observed four clearly distinguishable cracking methods during walnut feeding in the 17 subjects. The compositions of five behavioral elements were different in each method. These results suggest that walnut feeding by Japanese macaques is not only by brute force but requires the acquisition of at least one of four cracking methods for the achievement of complete cracking. In particular, females need to compensate for their physical inferiority by increasing walnut manipulations. To my knowledge, this is the first detailed description on feeding techniques in primates to overcome hard‐shelled obstacles without the use of tools and even substrates.
Illustrations and photographs of walnuts being processed with four cracking methods. (a) crunch, (b) bilateral‐crack, (c) unilateral‐crack, and (d) hole‐punch. Photos accompanying crunch are from video footage. Other photos are of feeding traces when monkeys gave up feeding. Black areas in the illustrations indicate cracked parts of the shell. Small arrows on the walnuts indicate directions of cracking.
Research Highlights
Wild Japanese macaques in Kinkazan Island required not only physical strength but also some feeding techniques for achieving hard‐shelled walnut feeding tasks.
The monkeys showed four clearly distinguishable cracking methods during the tasks.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Realizing capacitive coupling under seawater is difficult, although the capacitive coupler attracts attention as a promising solution for wireless power and data transfer. The coupler consisting of ...parallel-plate electrodes (e.g., capacitive coupler) has strong conductive coupling because of the high conductivity of seawater. This study introduces the design of a highly efficient coupler utilizing this phenomenon as a novel method. First, the operational principle of the highly efficient conductive coupler is clarified by comparing it to a conventional conductive coupler. The results reveal the key factor for the high-efficiency design. The design parameters at the maximum available efficiency are derived. The designed coupler is then fabricated. A demonstration shows that the efficiency of over 90% under seawater is achieved at a 20-mm transfer distance and a 1-kW transfer power. The demonstration also shows that power is wirelessly transferred to a camera module via the coupler, with the transferred data recorded by the camera appearing on a laptop computer.
This paper presents the design of a capacitive coupler for underwater wireless power transfer focused on the landing direction of a drone. The main design feature is the relative position of power ...feeding/receiving points on the coupler electrodes, which depends on the landing direction of the drone. First, the maximum power transfer efficiencies of coupled lines with different feeding positions are derived in a uniform dielectric environment, such as that realized underwater. As a result, these are formulated by the coupling coefficient of the capacitive coupler, the unloaded qualify factor of dielectrics, and hyperbolic functions with complex propagation constants. The hyperbolic functions vary depending on the relative positions and whether these are identical or opposite couplers, and the efficiencies of each coupler depend on the type of water, such as seawater and tap water. The design method was demonstrated and achieved the highest efficiencies of 95.2%, 91.5%, and 85.3% in tap water at transfer distances of 20, 50, and 100 mm, respectively.
Couplers in a film-type capacitive wireless power charging (CWC) system for an implantable medical device were designed and analyzed in this work. Due to the high conductivity of the human body, two ...paths contribute to the power transmission, namely a high-frequency current and an electric field. This was confirmed by an equivalent circuit of the system. During analysis of the system, we used pig skin with subcutaneous fat, which has a high affinity with the human body, to search for a highly efficient electrode shape. Subsequently, we fabricated the designed coupler and measured ηmax. An ηmax of 56.6% was obtained for a half-circular coupler with a radius of 20 mm and a distance of 10 mm between adjacent couplers. This study will contribute to the realization of implantable devices that can be recharged during breaks or while sleeping at home and is expected to significantly reduce the burden on patients.
This letter proposes a planar capacitive power transmitter (Tx) and differential power receiver (Rx) for cavity resonance-enabled wireless power transfer. The power Tx consists of an inverted ...L-shaped open stub. The power Rx consists of two inverted L-shaped open stubs based on method of image, and a differential output can be obtained by it. Our power Tx and Rx are explained by the equivalent circuits and are designed through electromagnetic simulation. From the measurement results at multiple positions, it was revealed that the higher RF-dc efficiency was achieved at all positions than the conventional monopole probes.
This study aims to realize an efficient system operation using wireless sensor networks (WSNs), which have been increasing in demand in recent years. To achieve this, a cavity resonance-enabled ...wireless power transfer (CR-WPT) technique has been proposed. The CR-WPT system is a WPT system that utilizes the cavity resonance phenomenon inside the cavity. This study solves the impedance mismatch problem caused by the resonance frequency changes depending on the installation condition of objects in the cavity resonator, which results in a power transmission efficiency(PTE) decrease. We propose the implementation of J-inverters and additional resonators outside and inside the cavity resonator and the configuration of a three-stage band-pass filter(BPF) to achieve broadband matching. The EM analysis results show that adding the J-inverters and additional resonators produces three poles in the reflection characteristics, verifying the proposed system operates as a three-stage BPF. A broadwidth of the power-supply frequency is realized. With a 2 W power input in the 117-122 MHz band, the bandwidth was broadened from approximately 0.6 to 2.0 MHz, which is approximately thrice the bandwidth of the previous system.
The misalignment of a coupler is a significant issue for capacitive wireless power transfer (WPT). This paper presents a capacitive WPT system specifically designed for underwater drones operating in ...flowing freshwater environments. The primary design features include a capacitive coupler with an opposite relative position between feeding and receiving points on the coupler electrode, two phase compensation circuits, and a load-independent inverter. A stable and energy-efficient power transmission is achieved by maintaining a 90° phase difference on the coupler electrode in dielectrics with a large unloaded quality factor (Q factor), such as in freshwater. Although a 622-mm coupler electrode is required at 13.56MHz, the phase compensation circuits can reduce to 250mm as one example, which is mountable to small underwater drones. Furthermore, the electricity waste is automatically reduced using the constant-current (CC) output inverter in the event of misalignment where efficiency drops occur. Finally, their functions are simulated and demonstrated at various receiver positions and transfer distances in tap water.
The load-independent zero-voltage switching class-E inverter has garnered considerable interest as an essential component in wireless power transfer systems. This inverter achieves high efficiency ...across a broad spectrum of load conditions by incorporating a load adjustment circuit (LAC) subsequent to the resonant filter. Nevertheless, the presence of the LAC influences the output impedance of the inverter, thereby inducing a divergence between the targeted and observed output power, even in ideal lossless simulations. Consequently, iterative adjustments to component values are required via an LC element implementation. We introduce a novel design methodology that incorporates an external quality factor on the side of the resonant filter, inclusive of the LAC. Thus, the optimized circuit achieves the intended output power without necessitating alterations in component values.
This study proposes a design method for a rectifier circuit that can be rapidly charged by focusing on the design-load value of the circuit and the load fluctuation of a storage capacitor. The ...design-load value is suitable for rapidly charging the capacitor. It can be obtained at the lowest reflection condition and estimated according to the circuit design. This is a conventional method for designing the rectifier circuit using the optimum load. First, we designed rectifier circuits for the following three cases. The first circuit design uses a load set to 10 kΩ. The second design uses a load of 30 kΩ that is larger than the optimum load. The third design utilizes a load of 3 kΩ. Then, we measure the charging time to design the capacitor on each circuit. Consequently, the results show that the charge time could be shortened by employing the design-load value lower than that used in the conventional design. Finally, we discuss herein whether this design method can be applied regardless of the rectifier circuit topology.
Objective
The purpose of this retrospective study was to investigate the utility of F-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F FDG-PET/CT) to predict spread through ...air spaces (STAS) in clinical stage I lung adenocarcinoma.
Methods
Between April 2020 and January 2022, 52 patients (55 lesions) who underwent surgery for clinical stage I lung adenocarcinoma were enrolled. The lesions were divided into two groups according to the presence of STAS. 18F FDG-PET/CT parameters, specifically the maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG), were calculated. The SUVmax, MTV, and TLG were compared between the two groups upon surgical pathological examination. Receiver operating characteristic (ROC) curve analysis was performed to identify a cut-off value.
Results
Nineteen lesions (35%) were positive for STAS and 36 lesions were negative for STAS. According to the presence of STAS, significant differences were detected in the SUVmax (5.21 range 1.52–16.50 vs. 2.42 range 0.74–11.80,
p
= 0.0040) but not MTV (3.44 range 0.65–24.36 vs. 2.95 0.00–20.07,
p
= 0.20) and TLG (7.92 range 0.93–47.82 vs. 5.63 0.00–58.66,
p
= 0.14). SUVmax had an AUC value of 0.74 (95% CI 0.61–0.87) with a sensitivity of 89.5% and specificity of 52.8% at a cut-off of 2.48.
Conclusions
SUVmax rather than MTV and TLG were shown to be valuable indices for the prediction of STAS in clinical stage I lung adenocarcinoma.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
