Feeding Circuit Research Articles

An E-Band Partially Corporate Feed Uniform Slot Array With Laminated Quasi Double-Layer Waveguide and Virtual PMC Terminations

A partially corporate feeding waveguide located below the radiating waveguide is introduced to a waveguide slot array to enhance the bandwidth of gain. A PMC termination associated with the symmetry of the feeding waveguide as well as uniform excitation is newly proposed for realizing dense and uniform slot arrangement free of high sidelobes. To exploit the bandwidth of the feeding circuit, the 4 × 4-element subarray is also developed for wider bandwidth by using standing-wave excitation. A 16 × 16-element array with uniform excitation is fabricated in the E-band by diffusion bonding of laminated thin copper plates which has the advantages of high precision and high mass-productivity. The antenna gain of 32.4 dBi and the antenna efficiency of 83.0% are measured at the center frequency. The 1 dB-down gain bandwidth is no less than 9.0% and a wideband characteristic is achieved.

3D optical Yagi–Uda nanoantenna array

Future photonic circuits with the capability of high-speed data processing at optical frequencies will rely on the implementation of efficient emitters and detectors on the nanoscale. Towards this goal, bridging the size mismatch between optical radiation and subwavelength emitters or detectors by optical nanoantennas is a subject of current research in the field of plasmonics. Here we introduce an array of three-dimensional optical Yagi–Uda antennas, fabricated using top-down fabrication techniques combined with layer-by-layer processing. We show that the concepts of radiofrequency antenna arrays can be applied to the optical regime proving superior directional properties compared with a single planar optical antenna, particularly for emission and reception into the third dimension. Measuring the optical properties of the structure reveals that impinging light on the array is efficiently absorbed on the subwavelength scale because of the high directivity. Moreover, we show in simulations that combining the array with suitable feeding circuits gives rise to the prospect of beam steering at optical wavelengths.

Zebrafish in Endocrine Systems: Recent Advances and Implications for Human Disease

Since its introduction as a genetic vertebrate model system approximately 30 years ago, the focus of zebrafish research has increasingly shifted to questions that are also relevant for human development and disease. Here, we review the potential of the zebrafish as a model for human endocrine systems. A recent review compared the functions of the different endocrine systems and glands in zebrafish with those in other vertebrates, including humans, coming to the conclusion that major aspects are conserved. Here, we present an updated overview of this rapidly growing field of zebrafish research, focusing on the hypothalamo-pituitary axis, which links the central nervous system with the endocrine systems, and on major processes that are under (neuro)endocrine control and are the subject of intensive current research in other endocrine model organisms, such as feeding circuits and energy homeostasis, sleep, stress, reproduction, osmoregulation, and calcium homeostasis. Finally, we summarize the strengths and weaknesses of zebrafish as a model for studying endocrine systems.

Respective Contributions of Maternal Insulin Resistance and Diet to Metabolic and Hypothalamic Phenotypes of Progeny

Maternal obesity can influence susceptibility to obesity and type 2 diabetes in progeny. We examined the relationship of maternal insulin resistance (IR), a metabolically important consequence of increased adiposity, to adverse consequences of obesity for fetal development. We used mice heterozygous for a null allele of the insulin receptor (Insr) to study the contributions of maternal IR to offspring phenotype without the potential confound of obesity per se, and how maternal consumption of high-fat diet (HFD) may, independently and interactively, affect progeny. In progeny fed a 60% HFD, body weight and adiposity were transiently (5-7 weeks) increased in wild-type (+/+) offspring of Insr(+/-) HFD-fed dams compared to offspring of wild-type HFD-fed dams. Offspring of HFD-fed wild-type dams had increased body weight, blood glucose, and plasma insulin concentrations compared to offspring of chow-fed wild-type dams. Quantification of proopiomelanocortin (POMC) and neuropeptide-Y (NPY) populations in the arcuate nucleus of the hypothalamus (ARH) of offspring of wild-type vs. Insr(+/-) dams was performed to determine whether maternal IR affects the formation of central feeding circuits. We found a 20% increase in the number of Pomc-expressing cells at postnatal day 9 in offspring of Insr(+/-) dams. In conclusion, maternal HFD consumption-distinct from overt obesity per se-was a major contributor to increased body weight, adiposity, IR, and liver triglyceride (TG) phenotypes in progeny. Maternal IR played a minor role in predisposing progeny to obesity and IR, though it acted synergistically with maternal HFD to exacerbate early obesity in progeny.

Early-Life Exposure to Testosterone Programs the Hypothalamic Melanocortin System

In mammals, males consume more food, which is considered a masculinized behavior, but the underlying mechanism of this sex-specific feeding behavior is unknown. In mice, neonatal testosterone (NT) is critical to masculinize the developing brain, leading to sex differences in reproductive physiology. The proopiomelanocortin (POMC) neurons of the hypothalamic arcuate nucleus (ARC) are critical to suppress energy intake and POMC innervation of hypothalamic feeding circuits develops to a large extent neonatally. We hypothesized that NT programs the masculinization of energy intake by programming POMC neurons. We tested this hypothesis by comparing control females and control males (CMs) with female mice neonatally androgenized with testosterone (NTFs). We show that increased food intake in CMs is associated with reduced POMC expression and decreased intensity of neuronal projections from POMC neurons within the ARC compared with control females. We found that NTFs display a masculinized energy intake and ARC POMC expression and innervation as observed in CMs, which can be mimicked by neonatal exposure to the androgen receptor agonist dihydrotestosterone (DHT). NTFs also exhibit hyperleptinemia and a decreased ability of leptin to up-regulate POMC, suppress food intake, and prevent adipose tissue accumulation, independent of signal transducer and activator of transcription 3. However, this leptin resistance is specific to NTFs, is not a consequence of masculinization, and is reproduced by neonatal exposure to estrogen but not DHT. Thus, NT programs a sexual differentiation of POMC neurons in female mice via DHT but also predisposes to leptin resistance and obesity in an estrogen-dependent manner.

Fto immunoreactivity is widespread in the rodent brain and abundant in feeding-related sites, but the number of Fto-positive cells is not affected by changes in energy balance

A single nucleotide polymorphism in the FTO gene is associated with obesity in humans. Evidence gathered in animals mainly relates energy homeostasis to the central FTO mRNA levels, but our knowledge of the Fto protein distribution and regulation is limited. Fto, a demethylase and transcriptional coactivator, is thought to regulate expression of other genes. Herein, we examined Fto immunoreactivity (IR) in the mouse and rat brain with emphasis on sites governing energy balance. We also studied whether energy status affects central Fto IR. We report that Fto IR, limited to nuclear profiles, is widespread in the brain, in- and outside feeding circuits; it shows a very similar distribution in feeding-related sites in mice and rats. Several areas regulating energy homeostasis display enhanced intensity of Fto staining: the arcuate, paraventricular, supraoptic, dorsomedial, ventromedial nuclei, and dorsal vagal complex. Some regions mediating feeding reward, including the bed nucleus of the stria terminalis, have ample Fto IR. We found that differences in energy status between rats fed ad libitum, deprived or refed following deprivation, did not affect the number of Fto-positive nuclei in 10 sites governing consumption for energy or reward. We conclude that Fto IR, widespread in the rodent brain, is particularly abundant in feeding circuits, but the number of Fto-positive neurons is unaffected by changes in energy balance.

The anterior piriform cortex is sufficient for detecting depletion of an indispensable amino acid, showing independent cortical sensory function.

Protein synthesis requires a continuous supply of all of the indispensable (essential) amino acids (IAAs). If any IAA is deficient, animals must obtain the limiting amino acid by diet selection. Sensing of IAA deficiency requires an intact anterior piriform cortex (APC), but does it act alone? Shortly after rats begin eating an IAA-deficient diet, the meal ends and EPSPs are activated in the APC; from there, neurons project to feeding circuits; the meal ends within 20 min. Within the APC in vivo, uncharged tRNA activates the general amino acid control non-derepressing 2 (GCN2) enzyme system increasing phosphorylation of eukaryotic initiation factor (P-eIF2α), which blocks general protein synthesis. If this paleocortex is sufficient for sensing IAA depletion, both neuronal activation and P-eIF2α should occur in an isolated APC slice. We used standard techniques for electrophysiology and immunohistochemistry. After rats ate IAA-devoid or -imbalanced diets, their depleted slices responded to different stimuli with increased EPSP amplitudes. Slices from rats fed a control diet were bathed in artificial CSF replete with all amino acids with or without the IAA, threonine, or a tRNA synthetase blocker, l-threoninol, or its inactive isomer, d-threoninol. Thr depletion in vitro increased both EPSP amplitudes and P-eIF2α. l (but not d)-threoninol also increased EPSP amplitudes relative to control. Thus, we show independent excitation of the APC with responses parallel to those known in vivo. These data suggest a novel idea: in addition to classical processing of peripheral sensory input, direct primary sensing may occur in mammalian cortex.

AGRP neurons are sufficient to orchestrate feeding behavior rapidly and without training.

Two intermingled hypothalamic neuron populations, specified by expression of agouti-related peptide (AGRP) or pro-opiomelanocortin (POMC), positively and negatively influence feeding behavior respectively, possibly by reciprocally regulating downstream melanocortin receptors. However, the sufficiency of these neurons to control behavior, and the relationship of their activity to the magnitude and dynamics of feeding are unknown. To measure this, we used channelrhodopsin-2 for cell type-specific photostimulation. Activation of only 800 AGRP neurons in mice evoked voracious feeding within minutes. The behavioral response increased with photoexcitable neuron number, photostimulation frequency, and stimulus duration. Conversely, POMC neuron stimulation reduced food intake and body weight, which required melanocortin receptor signaling. However, AGRP neuron-mediated feeding was not dependent on suppressing this melanocortin pathway, indicating that AGRP neurons directly engage feeding circuits. Furthermore, feeding was evoked selectively over drinking without training or prior photostimulus exposure, which suggests that AGRP neurons serve a dedicated role coordinating this complex behavior.

Fault Current Analysis Considering Frequency Response of Feeding Circuits

Correct analysis of feeding circuits requires correct line constants of overhead lines and rails. Consideration of the frequency response of self-impedances and mutual impedances on steady state analysis is necessary because they affect calculation results. However, there are only a few reports on transient analysis of feeding circuits which take frequency response into account. This paper suggests a transient analysis model of overhead lines and rails with approximated frequency response, and shows the results of transient analysis on a simplified DC feeding circuit.

Miniaturized UWB Monopole Microstrip Antenna Design by the Combination of Giusepe Peano and Sierpinski Carpet Fractals

A fractal monopole antenna is proposed for the application in the UWB frequency range, which is designed by the combination of two fractal geometries. The first iterations of Giusepe Peano fractal are applied on the edges of a square patch, and a Sierpinski Carpet fractal is formed on its surface. The feed circuit is a microstrip line with a matching section over a semi-elliptical ground plane. The presented antenna has an omnidirectional radiation pattern, a good gain, and high efficiency. The fabrication and measurement data attest to the satisfaction of the design specifications.

Feeding Circuit for Switching Beams in Three Directions Using LC Phase Shifter

In order to obtain MMIC of a feed circuit called a HTBM (Hybrid Three Direction Beam Matrix) for making compact phased array antennas, the HTBM that uses LC circuitry as substitute for its transmission line was designed, experimentally fabricated and then evaluated at 1 MHz. In addition, a switch circuit for switching a beam direction was made using FETs and built into the HTBM. Antenna output was evaluated. Its results showed that the output gave close agreement with its simulation value and that the antenna-to-antenna phase difference and the level difference were less more than 7 degrees and 3.3 dB, respectively, in comparison with its ideal value.

Transition from Waveguide to Two Microstrip Lines with Slot Radiators in the Millimeter-Wave Band

Many kinds of microstrip array antennas have been developed in the millimeter-wave band. In order to avoid feeding loss and the decrease of antenna gain by beam shift due to frequency changes, center-fed array antennas are advantageous. In this case, the element spacing around the feeding circuit of the transition from the waveguide to two microstrip lines is larger than one wavelength. Therefore, the sidelobe level grows significantly. In order to suppress the sidelobe level, we propose transitions with slot radiators. Moreover, any polarization angles can be achieved by changing the slot angle. A wide variety from 1.5% to 70% of slot radiator coupling powers can be achieved. To investigate the performance of the proposed transition, 10, 22 and 30-element center-fed microstrip comb-line antennas with the proposed transition were developed at 76.5GHz, and measured performance was evaluated in the millimeter-wave band.

Autaptic excitation contributes to bistability and rhythmicity in the neural circuit for feeding in Aplysia

The feeding circuit in Aplysia is a useful model system for studying the neuronal bases of cognitive functions such as sensory processing, generation of behavior, motivation, decision making, learning, and memory [1,2]. The goals of the present study are to develop a biologically-realistic model of the feeding circuit and to investigate the ways in which component processes contribute to circuit function. To begin, we developed a model of the central pattern generator (CPG) that mediates rhythmicity in the feeding circuit (Fig. ​(Fig.1A).1A). Simulations indicated that two positive-feedback loops (the B31 autapse and the synaptic interactions between B31 and B63) introduced bistability into the membrane potential of the B31 soma (Figures ​(Figures1B,1B, 1C1). In addition, simulations indicated that this plateau-like potential was the ‘deciding factor’ for initiating rhythmic activity (Fig. ​(Fig.1C).1C). Simulations also helped identify features of the model that warrant further empirical investigation; e.g., the simulated amplitude of the plateau-like potential was less than empirical observations. Figure 1 Bistability and rhythmicity in the feeding circuit. A: Circuit diagram of the feeding CPG. We expanded our previous ten-cell model [3] by representing B31 and B63 with two-compartments (soma and axon compartments), incorporating a modulatory synapse ...

A Broadband Folded Printed Quadrifilar Helical Antenna Employing a Novel Compact Planar Feeding Circuit

A broadband printed quadrifilar helical antenna employing a novel compact feeding circuit is proposed in this paper. This antenna presents an excellent axial ratio over a wide beamwidth, with a 29% bandwidth. A specific feeding circuit based on an aperture-coupled transition and including two 90° surface mount hybrids has been designed to be integrated with the quadrifilar antenna. Over the bandwidth, the measured reflection coefficient of the antenna fed by the wideband compact circuit has been found to be equal to or lower than -12 dB and the maximum gain varies between 1.5 and 2.7 dBic from 1.18 to 1.58 GHz. The half-power beamwidth is 150°, with an axial ratio below 3 dB over this range. The compactness of the feeding circuit allows small element spacing in array arrangements.

The melanocortins, not oxytocin, mediate the anorexigenic and antidipsogenic effects of neuronostatin

Neuronostatin, a recently discovered peptide derived from the somatostatin preprohormone, significantly inhibited both food and water intake when administered centrally in adult male rats. Because neuronostatin is highly produced in the hypothalamus, an area of the brain through which important feeding circuits, including the central melanocortin system, communicate, we sought to determine if the anorexigenic and antidipsogenic effects of neuronostatin would be reversed by pretreatment with the melanocortin 3/4 receptor antagonist, SHU9119. SHU9119 pretreatment reversed the effect of neuronostatin on both food and water intake. We have shown recently that the central oxytocin system is a potential downstream mediator of the anorexignic action of alpha-MSH. We therefore tested whether the effects of neuronostatin also were dependent upon central oxytocin receptors. Neuronostatin-induced anorexia was not reversed by pretreatment with the oxytocin receptor antagonist, OVT, suggesting that neuronostatin acts through a unique subset of POMC neurons that do not signal via central oxytocin receptors.

Improvement of modes and circuits of bacterial leaching of sulfide concentrates

These studies are devoted to the effect of the feed circuit of a series of chemostats on the characteristics of bacterial leaching of sulfide concentrates. The parameters and modes of the process are investigated at a laboratory installation consisting of five operating reactors, each with an active volume of 1.5 l and a conditioning tank. The initial material was a gold-bearing arsenical pyrite flotation concentrate containing Au, Ag, and As, as well as a specially adapted bacterial strain, namely, Acidithiobacillus ferrooxidans. It is established that double-flow feeding of a series of chemostats makes it possible to increase the leaching yield up to a 70% excess of the critical rate of dilution under the single-flow feeding mode at the same degree of oxidation of output sulfide minerals.

Energy Saving Techniques for the Power Feeding Network of Electric Railways

AbstractElectric railcars using current collection are generally more energy efficient than battery‐powered cars in terms of charge/discharge losses in the batteries. However, in electric railway systems, high resistive losses in the feeding circuit can be observed, as well as low line receptivity for regenerative braking trains in the DC railways. Several new techniques are being developed to improve the situation, which will enable further reduction of energy lost in the feeding network. This work classifies the possible approaches and discusses the possibilities of the emerging techniques. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

InsR/FoxO1 signaling affects neuroanatomy of hypothalamic POMC neurons

The insulin-regulated transcription factor FoxO1 functions as a major metabolic integrator in the hypothalamic feeding center and controls melanocortinergic tone. By inhibiting FoxO1, Insulin receptor (InsR) signaling regulates gene transcription in hypothalamic POMC neurons. While a role of InsR/FoxO1 signaling in the development of neuronal feeding circuits in the hypothalamus has become evident, knowledge about the underlying mechanisms remains vague. Many studies have investigated the role of the maternal environment in this context, but the role of InsR/FoxO1 signaling in hypothalamic POMC neurons themselves remains unknown. To investigate the role of InsR/FoxO1 signaling for development and maintenance of these cells, we first examined hypothalamic Pomc mRNA-expressing neurons by fluorescent in situ hybridization in mice with hypothalamic deficiency of InsR (L1). Neonatal and pre-pubertal L1 mice showed no difference in the number of Pomc-positive cells as compared to controls, suggesting that ontogeny of POMC neurons is intact in these mice. In contrast, young adult (15-week-old) L1 mice showed a 25% increase in the total number of neurons expressing Pomc, most notably in the caudal arcuate nucleus of the hypothalamus (Bregma –1.4 to –1.9mm). To determine the contribution of cell-autonomous InsR/Foxo1 function, we further generated L1 mice with selective over-activation of InsR signaling in POMC neurons (L1-Pomc+InsR), and found that the number of Pomc-positive cells in these mice was reduced by 10% compared to L1. Along this line, young adult mice with POMC-specific deletion of FoxO1 (PomcΔFoxo1) showed a 19% decrease in Pomc cell number compared to wild type controls, but again no alteration of Pomc neuron number at postnatal or pre-pubertal age. These data are consistent with a cell-autonomous role of InsR/FoxO1 in reducing POMC neuron number or silencing Pomc expression, distinct from the established role of InsR signaling in activating Pomc neuropeptide transcription through FoxO1 inhibition. Importantly, these changes in Pomc cells cannot be explained by changes in humoral factors or reciprocal changes in hypothalamic NPY neurons. Interestingly, aging is correlated with a decline in hypothalamic POMC neurons, as 30-week-old wild type mice exhibit 26% fewer Pomc-positive cells than 15-week-old mice. This aging-associated trimming of POMC neurons is not affected in L1 or PomcΔFoxo1 mice. Thus, our data support the model that InsR/Foxo1 signaling acts as a cell-autonomous gauge of ambient insulin sensitivity to direct POMC neuronal development between puberty and young adulthood.

Compact feed circuit with quarter‐wavelength transmission line matrix controlling beams in three directions including boresight

AbstractA compact feed circuit with a λ/4 transmission line matrix circuit for use in array antennas to control beams in three directions, including boresight, is presented. The feed circuit antenna is composed of five switches and λ/4 transmission lines, and the feeding matrix circuit yields phase differences of ±90° and 0°. The feed circuit can obtain a reliable output signal, as there is only a small degree of deviation of output signal with variations in the line width. The feed circuit is simulated, fabricated, and evaluated for the ISM band, and the measured characteristics agree well with the results of the simulation. The size of the feed circuit is 45 (H) ×48 (W) ×3 (T) mm. © 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 93(4): 10–17, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10218

Pomc-expressing progenitors give rise to antagonistic neuronal populations in hypothalamic feeding circuits

Hypothalamic neuron circuits regulating energy balance are highly plastic and develop in response to nutrient and hormonal cues. To identify processes that might be susceptible to gestational influences in mice, we characterized the ontogeny of proopiomelanocortin (POMC) and neuropeptide Y (NPY) cell populations, which exert opposing influences on food intake and body weight. These analyses revealed that Pomc is broadly expressed in immature hypothalamic neurons and that half of embryonic Pomc-expressing precursors subsequently adopt a non-POMC fate in adult mice. Moreover, nearly one quarter of the mature NPY+ cell population shares a common progenitor with POMC+ cells.