Wideband open stub BPF for cognitive radio system applications

Shrestha, Bhanu,Yi, Jeong Hyun,Cho, Seongsoo Inderscience Enterprises Ltd. 2017 International journal of sensor networks Vol.25 No.3

Mechanisms of Carboxylic Acid Attraction in Drosophila melanogaster

Bhanu Shrestha,이영석 한국분자세포생물학회 2021 Molecules and cells Vol.44 No.12

Sour is one of the fundamental taste modalities that enable taste perception in animals. Chemoreceptors embedded in taste organs are pivotal to discriminate between different chemicals to ensure survival. Animals generally prefer slightly acidic food and avoid highly acidic alternatives. We recently proposed that all acids are aversive at high concentrations, a response that is mediated by low pH as well as specific anions in Drosophila melanogaster. Particularly, some carboxylic acids such as glycolic acid, citric acid, and lactic acid are highly attractive to Drosophila compared with acetic acid. The present study determined that attractive carboxylic acids were mediated by broadly expressed Ir25a and Ir76b, as demonstrated by a candidate mutant library screen. The mutant deficits were completely recovered via wild-type cDNA expression in sweet-sensing gustatory receptor neurons. Furthermore, sweet gustatory receptors such as Gr5a, Gr61a, and Gr64a-f modulate attractive responses. These genetic defects were confirmed using binary food choice assays as well as electrophysiology in the labellum. Taken together, our findings demonstrate that at least two different kinds of receptors are required to discriminate attractive carboxylic acids from other acids.

Symmetric Microstrip Meanderspurline Bandstop Filter

Bhanu Shrestha,Chae Bong Sohn 한국디지털융합학회 2016 IJICTDC Vol.1 No.1

In this paper, a symmetric microstrip meander spurline bandstop filter (SMMBF) is designed and simulated for X-band applications. The designed bandstop filter has a bandstop characteristic with higher insertion loss. The operating resonance frequencies of the bandstop filter is 9.2 GHz with insertion loss of less than 28 dB and return losses are below 1 dB. The miniaturized resonator filters consist of symmetric meander spurline with inductive and capacitive characteristics. The capacitive loaded spurline resonator filter provides a band rejection frequency response. The quality factor (Q) of the resonators filter is good for implementing in microwave oscillators too. Implementation of such resonator filter in MMIC technology is also possible due to their inherent capability to integrate into small sizes.

Cellular and molecular mechanisms of DEET toxicity and disease-carrying insect vectors: a review

Bhanu Shrestha,Youngseok Lee 한국유전학회 2020 Genes & Genomics Vol.42 No.10

Background Several insects such as mosquitoes, fies, ticks, feas, lice, and mites are known to serve as vectors for a vast number of pathogens. Many such vectors are hematophagous, and therefore introduce pathogens directly into the host’s bloodstream. Importantly, the capacity of these vectors to spread disease can lead to serious global health crises. Furthermore, crop damage can be exacerbated by pathogen infection and increased insect foraging due to recent global warming. Methods Our study categorized insect-associated damage into three groups: animal infection, plant infection, and direct crop damage due to insect foraging. To manage these problems, insect repellents and pesticides have been developed, among which DEET is the most broadly used and studied pest control agent. This review discusses the mode of action and possible mechanisms of DEET action, including olfactory and gustatory mechanisms and central nervous system impairment. Conclusion To protect humans from malaria, yellow fever, dengue fever, zika, and flariasis, as well as to reduce economic losses associated with crop damage, considerably more eforts are needed to characterize the interactions between insects and insect repellents/pesticides to develop more potent pest control agents.

Microstrip Bandstop Filter based on Coupled SIR for Communication Systems

Bhanu Shrestha 한국디지털융합학회 2018 IJICTDC Vol.3 No.1

In this paper, a microstrip bandstop filter (BSF) is designed and simulated for X-band wireless communication system. It consists of open stubs (parallel line with T-shaped) coupled with high impedance of stepped impedance resonator (SIR) at 7.5 GHz for X-band system applications. All the stubs are optimized to have the stopband characteristics. The layout pattern is simulated using Sonnet EM tool on Teflon substrate with a dielectric constant of 2.54 and thickness of 0.54 mm. The main features of this work are smaller size, low cost, and controllable bandwidth. The bandwidth can be controlled by adjusting the parallel line open stubs connected with open T-stub. The 3dB bandwidth is achieved as 0.3 GHz at 7.5 GHz with good frequency responses. The overall physical dimension of the designed BSF is 23.62 mm by 8.0 mm excluding reference lines.

Review: Phase Noise in Voltage Controlled Oscillator

Bhanu Shrestha 한국디지털융합학회 2016 IJICTDC Vol.1 No.2

In this work, the review of phase noise in voltage controlled oscillator (VCO) which is very important system in all kinds of wireless communication system is presented. Such kinds of VCOs can be fabricated by hybrid method using PCB substrate or by semiconductor technology using silicon, GaAs, InP, complementary metal oxide semiconductor (CMOS), micro-electromechanical sytems (MEMS) and so on. Recently there are many kinds of design tools like ADS, AWAR etc. for RF system design. Especially, the phase noise is essential parameter to be considered during the design and simulation process. Optimization of such parameter is also important in simulation because phase noise cannot be totally eliminated but it can be reduced using different techniques. If phase noise is maximum in the signal, spectrum purity cannot be expected, eventually, the system will be failed to extract the real signal. That means, the performance of the overall system will not be degraded by improving the VCO phase noise performance

Review: Ultra-wideband Wireless Communication System

Bhanu Shrestha,Kwang-Chul-Son 한국디지털융합학회 2017 IJICTDC Vol.2 No.1

In this article, the review on ultra-wideband (UBW) filter in wireless communication system is presented. The basic standard of UWB is defined by the federal communication committee (FCC) that the unlicensed frequency band that is 3.1 to 10.6 GHz. This UWB technology is emerging technology that uses very short radio pulse called Gaussian pulse. The advantage of such UWB is high data rate and high speed with low power consumption. In UWB system, transmitter and receiver are used in which in both systems, bandpass / bandstop filter with ultra-wideband bandwidth can be implemented. For this purpose, many researchers are concentrating to get UWB characteristics in filter using various kinds of filter design technologies.

Design of a Differential Colpitts Voltage Controlled Oscillator using InGaP/GaAs HBT Technology for an ICS Application

Bhanu Shrestha,Jae-Ho Yoon,Sang-Hoon Cheon,Nam-Young Kim 한국통신학회 2006 한국통신학회 학술대회논문집 Vol.2006 No.7

MMIC Cascode VCO with Low Phase Noise in InGaP/GaAs HBT Process for Ku-Band Application

Bhanu Shrestha,Jae-Young Lee,Jeiyoung Lee,Sang-Hoon Cheon,Nam-Young Kim 한국전자파학회JEES 2004 Journal of Electromagnetic Engineering and Science Vol.4 No.4

The MMIC cascode VCO is designed, fabricated, and measured for Ku-band Low Noise Blcok(LNB) system using InGaP/GaAs HBT technology The phase noise of -116.4 ㏈c/Hz at 1㎒ offset with output power of 1 3 dBm is obtained at 11.526㎓ by applying 3 V and 11 mA, which is comparatively better characteristics than compared with the different configuration VCOs fabricated with other technologies. The simulated results of oscillation frequency and second harmonic suppression agree with the measured results The phase noise is Improved due to the use of the smallest value of inductor m frequency determining network and the InGaP ledge function of the technology The chip size of 830×781㎛² is also achieved.

Molecular sensors in the taste system of Drosophila

Shrestha Bhanu,Lee Youngseok 한국유전학회 2023 Genes & Genomics Vol.45 No.6

Background Most animals, including humans and insects, consume foods based on their senses. Feeding is mostly regulated by taste and smell. Recent insect studies shed insight into the cross-talk between taste and smell, sweetness and temperature, sweetness and texture, and other sensory modality pairings. Five canonical tastes include sweet, umami, bitter, salty, and sour. Furthermore, other receptors that mediate the detection of noncanonical sensory attributes encoded by taste stimuli, such as Ca2+, Zn2+, Cu2+, lipid, and carbonation, have been characterized. Deorphanizing receptors and interactions among different modalities are expanding the taste field. Methods Our study explores the taste system of Drosophila melanogaster and perception processing in insects to broaden the neuroscience of taste. Attractive and aversive taste cues and their chemoreceptors are categorized as tables. In addition, we summarize the recent progress in animal behavior as affected by the integration of multisensory information in relation to different gustatory receptor neuronal activations, olfaction, texture, and temperature. We mainly focus on peripheral responses and insect decision-making. Conclusion Drosophila is an excellent model animal to study the cellular and molecular mechanism of the taste system. Despite the divergence in the receptors to detect chemicals, taste research in the fruit fly can offer new insights into the many different taste sensors of animals and how to test the interaction among different sensory modalities.