Compact, Low-Profile, Bandwidth-Enhanced Substrate Integrated Waveguide Filtenna

© 2011 IEEE. In this letter, a compact, low-profile, bandwidth-enhanced, dual-cavity substrate integrated waveguide (SIW) filtenna is demonstrated. Two SIW cavities are stacked vertically on top of each other. A complementary split-ring resonator slot is etched in the top surface of the uppermost cavity, causing the top surface to act as a patch antenna. The operational impedance bandwidth is significantly enhanced by merging the three resonances that arise from this configuration. One is introduced by the patch, and the other two are inherently generated by the two cavities. A metallized coupling post is introduced from the ground plane through both cavities to the upper surface to excite the fundamental resonant mode of the patch, as well as to electromagnetically couple the two cavities. The optimized filtenna was fabricated by a standard printed circuit board technology and tested. It has a low profile λ 0 and a compact size 0.62λ 0×0.62λ0 at its center frequency, f0=2.95GHz. The measured results agree well with their simulated values. They demonstrate a 6.3% fractional bandwidth, a maximum realized gain of 6.73 dBi, a flat gain profile within its passband, and an excellent out-of-band selectivity

Meta-Registration: Learning Test-Time Optimization for Single-Pair Image Registration

Neural networks have been proposed for medical image registration by learning, with a substantial amount of training data, the optimal transformations between image pairs. These trained networks can further be optimized on a single pair of test images - known as test-time optimization. This work formulates image registration as a meta-learning algorithm. Such networks can be trained by aligning the training image pairs while simultaneously improving test-time optimization efficacy; tasks which were previously considered two independent training and optimization processes. The proposed meta-registration is hypothesized to maximize the efficiency and effectiveness of the test-time optimization in the "outer" meta-optimization of the networks. For image guidance applications that often are time-critical yet limited in training data, the potentially gained speed and accuracy are compared with classical registration algorithms, registration networks without meta-learning, and single-pair optimization without test-time optimization data. Experiments are presented in this paper using clinical transrectal ultrasound image data from 108 prostate cancer patients. These experiments demonstrate the effectiveness of a meta-registration protocol, which yields significantly improved performance relative to existing learning-based methods. Furthermore, the meta-registration achieves comparable results to classical iterative methods in a fraction of the time, owing to its rapid test-time optimization process.Comment: Accepted to ASMUS 2022 Workshop at MICCA

Ab initio diffusional potential energy surface for CO chemisorption on Pd{110} at high coverage: Coupled translation and rotation

[[abstract]]The ground statepotential energy surface for CO chemisorption across Pd{110} has been calculated using density functional theory with gradient corrections at monolayer coverage. The most stable site corresponds well with the experimental adsorption heat, and it is found that the strength of binding to sites is in the following order: pseudo-short-bridge>atop>long-bridge>hollow. Pathways and transition states for CO surfacediffusion, involving a correlation between translation and orientation, are proposed and discussed.[[notice]]補正完畢[[journaltype]]國外[[booktype]]紙本[[countrycodes]]US

Diffusion tensor-based fiber tracking in cervical spinal cord with a 3T MRI

The protocol for spinal DTI nntl tractography with high SNR and spatial resolution has been developed arid tested on G healthy subjects and 1 CSM patient in a 3T system. Fiber bundlex were traced and were found running parallel to the cervical spinal cord correlating with the neuronal anatomy in normal subjects. The FA maps showed consistent low FA region connecting all spinal levels, which corresponded lo the grey matter structure in anatomical imaging, Spinal DTI in CSM showed diffusivity increase at compression sites. The proposed diffusion eigenvector-based method was able to differentiate between λa and λr even when there was a draxtic diffusivity change at compressed regions in CSM, which may facilitate better understanding of the pathophysiology of CSM. Our results indicated that using the current imaging and post-procensing protocols, spinal DTI can fm achieved with better grey white matter contrast, high inter-subject reproducibility and diagnostic ability. © 2006 IEEE.published_or_final_versio

Protective role of Phyllantus niruri extract on serum lipid profiles and oxidative stress in hepatocytes of diabetic rats

Diabetes mellitus has been associated with lipid abnormalities and oxidative stress. Some phytochemical properties have been shown to possess antioxidant activities, improving the effects of oxidative stress on diabetes. This present investigations confirmed that untreated diabetic rats were associated with lipid abnormalities as indicated by high levels of total- and LDL-cholesterol, triacylglycerols and low levels of HDL-cholesterol and phospholipids, compared to non-diabetic rats(control). The aqueous extract of Phyllanthus niruri significantly normalized the serum lipids levels. The study also showed that untreated diabetic rats were subjected to oxidative stress as indicated by significantly abnormal activities of their scavenging enzymes (superoxide dismutase and catalase and significantly low levels of non-enzymic antioxidants (vitamin C, vitamin E and reduced glutathione) in liver and plasma when compared with controls and in the extent of lipid peroxidation (increased malondialdehyde levels) in plasma and liver cells. The aqueous extract of P. niruri possessedantioxidant activities as shown by increased activities of enzymic and non-enzymic antioxidants and decrease in malondialdehyde levels

Oxidative stress and non-enzymic antioxidant status in hypertensive patients in Nigeria

Oxidative stress and non-enzymic antioxidant status in plasma of hypertensive patients in Nigeria were investigated. One hundred and fifty hypertensive patients (82 males and 68 females) age range 55 – 75 years visiting Federal Medical Centre, Owerri were selected for the study. Controls were 120 apparently healthy subjects (66 males and 54 females) age range 55 -75 years. Patients with complication such as renal diseases, viral and bacterial infections were excluded from the study. In The hypertensive patients presented significantly higher mean values of plasma total cholesterol, LDL-cholesterol and triacylglycerolsand reduced HDL-cholesterol and phospholipids (p < 0.05). The result of plasma lipid peroxide was significantly higher in hypertensive patients (p < 0.05). Also the levels of non-enzymic antioxidantssuch as Vitamin C, vitamin E and reduced glutathione in plasma were significantly depleted in the hypertensive patients (p < 0.05). This study shows that hypertension is associated with increasedoxidative stress and depleted non-enzymic antioxidant status even in developing countries like Nigeria

Changes in the expression of the type 2 diabetes-associated gene VPS13C in the β cell are associated with glucose intolerance in humans and mice

Single nucleotide polymorphisms (SNPs) close to the VPS13C, C2CD4A and C2CD4B genes on chromosome 15q are associated with impaired fasting glucose and increased risk of type 2 diabetes. eQTL analysis revealed an association between possession of risk (C) alleles at a previously implicated causal SNP, rs7163757, and lowered VPS13C and C2CD4A levels in islets from female (n = 40, P < 0.041) but not from male subjects. Explored using promoter-reporter assays in β-cells and other cell lines, the risk variant at rs7163757 lowered enhancer activity. Mice deleted for Vps13c selectively in the β-cell were generated by crossing animals bearing a floxed allele at exon 1 to mice expressing Cre recombinase under Ins1 promoter control (Ins1Cre). Whereas Vps13cfl/fl:Ins1Cre (βVps13cKO) mice displayed normal weight gain compared with control littermates, deletion of Vps13c had little effect on glucose tolerance. Pancreatic histology revealed no significant change in β-cell mass in KO mice vs. controls, and glucose-stimulated insulin secretion from isolated islets was not altered in vitro between control and βVps13cKO mice. However, a tendency was observed in female null mice for lower insulin levels and β-cell function (HOMA-B) in vivo. Furthermore, glucose-stimulated increases in intracellular free Ca2+ were significantly increased in islets from female KO mice, suggesting impaired Ca2+ sensitivity of the secretory machinery. The present data thus provide evidence for a limited role for changes in VPS13C expression in conferring altered disease risk at this locus, particularly in females, and suggest that C2CD4A may also be involved

Proton Density-weighted Spinal fMRI Comparison between Sensorimotor Task and Acupoint Stimulation

Proton density-weighted fMRI studies have been carried out in spinal cord in the current study. We compared the spinal cord activation produced by handgripping sensorimotor task and electro-acupuncture stimulation. Activation was detected in both cases localized at spinal levels C6-C7 (11/14 in sensorimotor and 7/11 in acupuncture stimulation). It was observed that the amount of activation in sensorimotor task was in general greater than in electroacupuncture stimulation. The percentage signal changes were found to be similar. Our results indicate that proton density-weighted fMRI in low field MRI system can be used for sensorimotor and acupuncture pathway research.published_or_final_versio

Functional MRI of the spinal cord at low field

A second contrast mechanism SEEP was reported to co-exist with BOLD during fMRI activation. The mechanism was based on the task-induced signal change of extravascular water protons and was primarily shown in the spinal cord at high field. Recently, a preliminary study was reported at 0.2T showing SEEP contrast in the brain while the BOLD effect was negligible. The present study is to investigate the presence of SEEP in the spinal cord at 0.2T using proton density-weighted imaging with motor task. Bilateral activations were obtained in the anterior grey horns consistently across C6-C8 levels, which correlated with the neural anatomy.published_or_final_versio