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"Wen, Lai"
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Chip Design of an All-Digital Frequency Synthesizer with Reference Spur Reduction Technique for Radar Sensing
2022
5.2-GHz all-digital frequency synthesizer implemented proposed reference spur reducing with the tsmc 0.18 µm CMOS technology is proposed. It can be used for radar equipped applications and radar-communication control. It provides one ration frequency ranged from 4.68 GHz to 5.36 GHz for the local oscillator in RF frontend circuits. Adopting a phase detector that only delivers phase error raw data when phase error is investigated and reduces the updating frequency for DCO handling code achieves a decreased reference spur. Since an all-digital phase-locked loop is designed, the prototype not only optimized the chip dimensions, but also precludes the influence of process shrinks and has the advantage of noise immunity. The elements of novelties of this article are low phase noise and low power consumption. With 1.8 V supply voltage and locking at 5.22 GHz, measured results find that the output signal power is −8.03 dBm, the phase noise is −110.74 dBc/Hz at 1 MHz offset frequency and the power dissipation is 16.2 mW, while the die dimensions are 0.901 × 0.935 mm2.
Journal Article
Self-templated synthesis of uniform hollow spheres based on highly conjugated three-dimensional covalent organic frameworks
2020
Covalent organic frameworks (COFs) have served as a family of porous crystalline molecules for various promising applications. However, controllable synthesis of COFs with uniform morphology is paramount yet still remains quite challenging. Herein, we report self-templated synthesis of uniform and unique hollow spheres based on highly conjugated three-dimensional (3D) COFs with diameters of 500–700 nm. A detailed time-dependent study reveals the continuous transformation from initial nano sphere-like particles into uniform hollow spherical structures with Ostwald ripening mechanism. Particularly, the resulting 3D COF (3D-Sp-COF) is prone to transport ions more efficiently and the lithium-ion transference number (
t
+
) of 3D-Sp-COF reaches 0.7, which even overwhelms most typical PEO-based polymer electrolytes. Inspiringly, the hollow spherical structures show enhanced capacitance performance with a specific capacitance of 251 F g
−1
at 0.5 A g
−1
, which compares favorably with the vast majority of two-dimensional COFs and other porous electrode materials.
Covalent organic frameworks (COFs) are promising porous crystalline materials but controllable synthesis of COFs with uniform morphology remains challenging. Here, the authors report a self-templated synthesis of uniform and unique hollow spheres based on highly conjugated three-dimensional COFs.
Journal Article
CD45 pre-exclusion from the tips of T cell microvilli prior to antigen recognition
2021
The tyrosine phosphatase CD45 is a major gatekeeper for restraining T cell activation. Its exclusion from the immunological synapse (IS) is crucial for T cell receptor (TCR) signal transduction. Here, we use expansion super-resolution microscopy to reveal that CD45 is mostly pre-excluded from the tips of microvilli (MV) on primary T cells prior to antigen encounter. This pre-exclusion is diminished by depleting cholesterol or by engineering the transmembrane domain of CD45 to increase its membrane integration length, but is independent of the CD45 extracellular domain. We further show that brief MV-mediated contacts can induce Ca
2+
influx in mouse antigen-specific T cells engaged by antigen-pulsed antigen presenting cells (APC). We propose that the scarcity of CD45 phosphatase activity at the tips of MV enables or facilitates TCR triggering from brief T cell-APC contacts before formation of a stable IS, and that these MV-mediated contacts represent the earliest step in the initiation of a T cell adaptive immune response.
CD45 limits T cell activation, so its exclusion from the T cell immunological synapse is thought to occur as a means to enable TCR signalling. Here the authors use a variety of cellular imaging methods to show that CD45 is indeed excluded from the tips of the T cell microvilli and that this occurs prior to contact with antigen, indicating this exclusion is one of the initiating factors for antigen presentation and T cell activation.
Journal Article
Simulation of summer precipitation diurnal cycles over the Tibetan Plateau at the gray-zone grid spacing for cumulus parameterization
by
Ou Tinghai
,
Chen, Deliang
,
Lin Changgui
in
Cloud parameterization
,
Clouds
,
Computer simulation
2020
The Tibetan Plateau (TP) is often referred to as the “water tower of Asia” or the “Third Pole”. It remains a challenge for most global and regional models to realistically simulate precipitation, especially its diurnal cycles, over the TP. This study focuses on evaluating the summer (June–August) precipitation diurnal cycles over the TP simulated by the Weather Research and Forecasting (WRF) model. The horizontal resolution used in this study is 9 km, which is within the gray-zone grid spacing that a cumulus parameterization scheme (CU) may or may not be used. We conducted WRF simulations with different cumulus schemes (CU experiments) and a simulation without CU (No_CU experiment). The selected CUs include the Grell-3D Ensemble (Grell), New Simplified Arakawa-Schubert (NSAS), and Multiscale Kain-Fritsch (MSKF). These simulations are compared with both the in-situ observations and satellite products. Results show that the scale-aware MSKF outperforms the other CUs in simulating precipitation in terms of both the mean intensity and diurnal cycles. In addition, the peak time of precipitation intensity is better captured by all the CU experiments than by the No_CU experiment. However, all the CU experiments tend to overestimate the mean precipitation and simulate an earlier peak of precipitation frequency when compared to observations. The frequencies and initiation timings for short-duration (1–3 h) and long-duration (> 6 h) precipitation events are well captured by the No_CU experiment, while these features are poorly reproduced by the CU experiments. The results demonstrate simulation without a CU outperforms those with a CU at the gray-zone spatial resolution in regard to the precipitation diurnal cycles.
Journal Article
High PD-L1 Expression Correlates with Metastasis and Poor Prognosis in Oral Squamous Cell Carcinoma
by
Hsieh, Ming-Ju
,
Lai, Hung-Wen
,
Yang, Shu-Mei
in
Alcohol use
,
Antigens
,
B7-H1 Antigen - biosynthesis
2015
PD-L1 has been widely demonstrated to contribute to failed antitumor immunity. Blockade of PD-L1 with monoclonal antibody could modulate the tumor immune environment to augment immunotherapy. PD-L1 expression is also detected in several types of cancer and is associated with poor prognosis. However, the prognostic role of PD-L1 in oral squamous cell carcinoma (OSCC) is still controversial. Our aim was to determine the role of PD-L1 in the prognosis of OSCC patients to identify its potential therapeutic relevance. PD-L1 immunoreactivity was analyzed by immunohistochemistry in 305 cancer specimens from primary OSCC patients. The medium follow-up time after surgery was 3.8 years (range from 0.1 to 11.1 years). The prognostic value of PD-L1 on overall survival was determined by Kaplan-Meier analysis and Cox proportional hazard models. Higher PD-L1 expression is more likely in tumor tissues of female than male OSCC patients (P = 0.0062). Patients with distant metastasis also had high PD-L1 expression (P = 0.0103). Multivariate analysis identified high PD-L1 expression as an independent risk factor in males and smokers (males: hazard ratio = 1.556, P = 0.0077; smokers: hazard ratio = 2.058, P = 0.0004). We suggest that PD-L1 expression, determined by IHC staining, could be an independent prognostic marker for OSCC patients who are male or who have a smoking habit.
Journal Article
Shotgun metagenomics reveals both taxonomic and tryptophan pathway differences of gut microbiota in major depressive disorder patients
2021
The microbiota-gut-brain axis, especially the microbial tryptophan (Trp) biosynthesis and metabolism pathway (MiTBamp), may play a critical role in the pathogenesis of major depressive disorder (MDD). However, studies on the MiTBamp in MDD are lacking. The aim of the present study was to analyze the gut microbiota composition and the MiTBamp in MDD patients.
We performed shotgun metagenomic sequencing of stool samples from 26 MDD patients and 29 healthy controls (HCs). In addition to the microbiota community and the MiTBamp analyses, we also built a classification based on the Random Forests (RF) and Boruta algorithm to identify the gut microbiota as biomarkers for MDD.
The Bacteroidetes abundance was strongly reduced whereas that of Actinobacteria was significantly increased in the MDD patients compared with the abundance in the HCs. Most noteworthy, the MDD patients had increased levels of Bifidobacterium, which is commonly used as a probiotic. Four Kyoto Encyclopedia of Genes and Genomes (KEGG) orthologies (KOs) (K01817, K11358, K01626, K01667) abundances in the MiTBamp were significantly lower in the MDD group. Furthermore, we found a negative correlation between the K01626 abundance and the HAMD scores in the MDD group. Finally, RF classification at the genus level can achieve an area under the receiver operating characteristic curve of 0.890.
The present findings enabled a better understanding of the changes in gut microbiota and the related Trp pathway in MDD. Alterations of the gut microbiota may have the potential as biomarkers for distinguishing MDD patients form HCs.
Journal Article
A preliminary study of rare-metal mineralization in the Himalayan leucogranite belts, South Tibet
by
WANG RuCheng WU FuYuan XIE Lei LIU XiaoChi WANG JiaMin YANG Lei LAI Wen LIU Chen
in
Beryllium aluminum silicates
,
Biotite
,
Cassiterite
2017
The Himalayan leucogranite occurs as two extensive(〉1000 km) E-W trending belts on the Tibetan Plateau with the unique features. The leucogranite comprised biotite granite, two-mica/muscovite granite, tourmaline granite and garnet granite, which have been identified in previous studies, as well as albite granite and granitic pegmatite that were identified in this investigation. Fifteen leucogranite plutons were studied and 12 were found to contain rare-metal bearing minerals such as beryl(the representative of Be mineralization), columbite-group minerals, tapiolite, pyrochlore-microlite, fergusonite, Nb-Ta rutile(the representative of Nb-Ta mineralization), and cassiterite(the representative of Sn mineralization) mainly based on the field trip,microscope observation and microprobe analysis. The preliminary result shows that the Himalayan leucogranite is commonly related to the rare-metal mineralization and warrants future investigation. Further exploration and intensive research work is important in determining the rare-metal resource potential of this area.
Journal Article
A 24 GHz End-Fire Rod Antenna Based on a Substrate Integrated Waveguide
2025
Most of the traditional rod antennas in the literature are in the shape of a cylinder or are conical, which are not suitable shapes for planar PCB technology or planar integrated CMOS or BiCMOS technology. In this paper, we present a 24 GHz planar end-fire rod antenna based on an SIW (substrate integrated waveguide) suitable for planar PCB technology or planar integrated circuit technology. The antenna is made of PCB Rogers 4350 and utilizes the SIW to realize the end-fire rod antenna. The measurement results of the antenna are presented: its gain is 8.55 dB and its S11 bandwidth is 6.2 GHz. This kind of planar end-fire rod antenna possesses the characteristics of high gain, wide bandwidth, compactness, and simple design and structure. This type of antenna can also be used as a PCB antenna in other frequency bands, and it could also possibly be utilized in mm-wave and THz integrated antenna design in the future due to its very simple architecture.
Journal Article
Glue-on AdS holography for TT¯-deformed CFTs
by
Lai, Wen-Xin
,
Hao, Peng-Xiang
,
Apolo, Luis
in
Boundary conditions
,
Classical and Quantum Gravitation
,
Deformation
2023
A
bstract
The
T
T
¯
deformation is a solvable irrelevant deformation whose properties depend on the sign of the deformation parameter
μ
. In particular,
T
T
¯
-deformed CFTs with
μ <
0 have been proposed to be holographically dual to Einstein gravity where the metric satisfies Dirichlet boundary conditions at a finite cutoff surface. In this paper, we put forward a holographic proposal for
T
T
¯
-deformed CFTs with
μ >
0, in which case the bulk geometry is constructed by gluing a patch of AdS
3
to the original spacetime. As evidence, we show that the
T
T
¯
trace flow equation, the spectrum on the cylinder, and the partition function on the torus and the sphere, among other results, can all be reproduced from bulk calculations in glue-on AdS
3
.
Journal Article
ObjectDetect: A Real-Time Object Detection Framework for Advanced Driver Assistant Systems Using YOLOv5
by
Murthy, Jamuna S.
,
Lai, Wen-Cheng
,
Hemalatha, K. L.
in
Accuracy
,
Advanced driver assistance systems
,
Algorithms
2022
In the recent times, there has been a lot of speculation related to advanced driver-assistance system (ADAS) which provides best driving experience for the drivers. ADAS technology helps to detect the unhealthy driving conditions which lead to road accidents today. Road accidents are basically caused due to distracted driving, over speeding, drink and drive, foggy weather, no proper headlights, or due to some object which suddenly trespasses the vehicle. Today the major advancements in ADAS include parking assistance, road traffic detection, object detection on highways, and lane detection. But the major risk limitation in ADAS system is the speed and time at which the object is detected and tracked. Several algorithms such as R-CNN, Fast R-CNN, and YOLO were used for effective object detection and tracking earlier, but sometimes, the system do fail to detect due the speed factor. Hence, the proposed work presents a novel approach called “A Real-Time Object Detection Framework for Advanced Driver Assistant Systems” by implementing the state-of-the-art object detection algorithm YOLOv5 which improves the speed in detection of object over real-time. This paper provides a comparison between other state-of-the-art object detectors such as YOLOv3 and YOLOv4. Comparison is done based on mean average precision (mAP) and frames per second (FPS) on three benchmark datasets collected as a part of research findings. YOLOv5 proves to be faster and 95% accurate than the other object detection algorithms in the comparison. This framework is used to build a mobile application called “ObjectDetect” which helps users make better decisions on the road. “ObjectDetect” consists of a simple user interface that displays alerts and warnings.
Journal Article