63 research outputs found
Semi-Supervised Learning with Graphs: Covariance Based Superpixels for Hyperspectral Image Classification
In this paper, we present a graph-based semi-supervised framework for
hyperspectral image classification. We first introduce a novel superpixel
algorithm based on the spectral covariance matrix representation of pixels to
provide a better representation of our data. We then construct a superpixel
graph, based on carefully considered feature vectors, before performing
classification. We demonstrate, through a set of experimental results using two
benchmarking datasets, that our approach outperforms three state-of-the-art
classification frameworks, especially when an extremely small amount of
labelled data is used.Case Studentship with the NP
Learning to See Forces: Surgical Force Prediction with RGB-Point Cloud Temporal Convolutional Networks
Robotic surgery has been proven to offer clear advantages during surgical
procedures, however, one of the major limitations is obtaining haptic feedback.
Since it is often challenging to devise a hardware solution with accurate force
feedback, we propose the use of "visual cues" to infer forces from tissue
deformation. Endoscopic video is a passive sensor that is freely available, in
the sense that any minimally-invasive procedure already utilizes it. To this
end, we employ deep learning to infer forces from video as an attractive
low-cost and accurate alternative to typically complex and expensive hardware
solutions. First, we demonstrate our approach in a phantom setting using the da
Vinci Surgical System affixed with an OptoForce sensor. Second, we then
validate our method on an ex vivo liver organ. Our method results in a mean
absolute error of 0.814 N in the ex vivo study, suggesting that it may be a
promising alternative to hardware based surgical force feedback in endoscopic
procedures.Comment: MICCAI 2018 workshop, CARE(Computer Assisted and Robotic Endoscopy
Multi-tasking to Correct: Motion-Compensated MRI via Joint Reconstruction and Registration
This work addresses a central topic in Magnetic Resonance Imaging (MRI) which
is the motion-correction problem in a joint reconstruction and registration
framework. From a set of multiple MR acquisitions corrupted by motion, we aim
at - jointly - reconstructing a single motion-free corrected image and
retrieving the physiological dynamics through the deformation maps. To this
purpose, we propose a novel variational model. First, we introduce an
fidelity term, which intertwines reconstruction and registration along with the
weighted total variation. Second, we introduce an additional regulariser which
is based on the hyperelasticity principles to allow large and smooth
deformations. We demonstrate through numerical results that this combination
creates synergies in our complex variational approach resulting in higher
quality reconstructions and a good estimate of the breathing dynamics. We also
show that our joint model outperforms in terms of contrast, detail and blurring
artefacts, a sequential approach.Cambridge Cancer Centre, CMIH and CCIMI, University of Cambridge
Electric-field-induced alignment of electrically neutral disk-like particles: modelling and calculation
This work reveals a torque from electric field to electrically neutral flakes that are suspended in a higher electrical conductive matrix. The torque tends to rotate the particles toward an orientation with its long axis parallel to the electric current flow. The alignment enables the anisotropic properties of tiny particles to integrate together and generate desirable macroscale anisotropic properties. The torque was obtained from thermodynamic calculation of electric current free energy at various microstructure configurations. It is significant even when the electrical potential gradient becomes as low as 100 v/m. The changes of electrical, electroplastic and thermal properties during particles alignment were discussed
Heat shock proteins in stabilization of spontaneously restored sinus rhythm in permanent atrial fibrillation patients after mitral valve surgery
A spontaneously restored sinus rhythm in permanent atrial fibrillation patients has been often observed after mitral valve (MV) surgery, but persisting duration in sinus rhythm varies from patient to patient. Heat shock proteins (Hsps) may be involved in pathogenesis of atrial fibrillation. We hypothesized that stabilization of restored sinus rhythm is associated with expression of Hsps in the atria. To test this hypothesis, clinical data, biopsies of right atrial appendage, and blood samples were collected from 135 atrial fibrillation patients who spontaneously restored sinus rhythm after conventional isolated MV replacement. Comparison was made between patients who had recurrence of atrial fibrillation within 7 days (AF) vs. patients with persisted sinus rhythm for more than 7 days (SR). Results showed that SR patients had higher activity of heat shock transcription factor 1 (HSF1) as well as upregulated expressions of heat shock cognate 70, Hsp70, and Hsp27 in the tissues. The activation of HSF1–Hsps pathway was associated with less-aggressive pathogenesis as reflected by lower rates of myolysis, apoptosis, interstitial fibrosis, and inflammation in SR patients. However, Hsp60 was lower in both tissue and plasma in SR patients, and was positively correlated with apoptosis, interstitial fibrosis, and inflammation. These findings suggest that the Hsps play important roles in stabilization of restored sinus rhythm after MV surgery by inhibiting AF-related atrial remodeling and arrhythmogenic substrates in atrial fibrillation patients. Low circulating Hsp60 levels preoperatively might predict a stable spontaneously restored sinus rhythm postoperatively
CD3Z Genetic Polymorphism in Immune Response to Hepatitis B Vaccination in Two Independent Chinese Populations
Vaccination against hepatitis B virus is an effective and routine practice that can prevent infection. However, vaccine-induced immunity to hepatitis B varies among individuals. CD4+ T helper cells, which play an important role in both cellular and humoral immunity, are involved in the immune response elicited by vaccination. Polymorphisms in the genes involved in stimulating the activation and proliferation of CD4+ T helper cells may influence the immune response to hepatitis B vaccination. In the first stage of the present study, a total of 111 single nucleotide polymorphisms (SNPs) in 17 genes were analyzed, using the iPLEX MassARRAY system, among 214 high responders and 107 low responders to hepatitis B vaccination. Three SNPs (rs12133337 and rs10918706 in CD3Z, rs10912564 in OX40L) were associated significantly with the immune response to hepatitis B vaccination (P = 0.008, 0.041, and 0.019, respectively). The three SNPs were analyzed further with the TaqMan-MGB or TaqMan-BHQ probe-based real-time polymerase chain reaction in another independent population, which included 1090 high responders and 636 low responders. The minor allele ‘C’ of rs12133337 continued to show an association with a lower response to hepatitis B vaccination (P = 0.033, odds radio = 1.28, 95% confidence interval = 1.01–1.61). Furthermore, in the stratified analysis for both the first and second populations, the association of the minor allele ‘C’ of rs12133337 with a lower response to hepatitis B vaccination was more prominent after individuals who were overweight or obese (body mass index ≥25 kg/m2) were excluded (1st stage: P = 0.003, 2nd stage: P = 0.002, P-combined = 9.47e-5). These findings suggest that the rs12133337 polymorphism in the CD3Z gene might affect the immune response to hepatitis B vaccination, and that a lower BMI might increase the contribution of the polymorphism to immunity to hepatitis B vaccination
Innate Immune Responses of Drosophila melanogaster Are Altered by Spaceflight
Alterations and impairment of immune responses in humans present a health risk for space exploration missions. The molecular mechanisms underpinning innate immune defense can be confounded by the complexity of the acquired immune system of humans. Drosophila (fruit fly) innate immunity is simpler, and shares many similarities with human innate immunity at the level of molecular and genetic pathways. The goals of this study were to elucidate fundamental immune processes in Drosophila affected by spaceflight and to measure host-pathogen responses post-flight. Five containers, each containing ten female and five male fruit flies, were housed and bred on the space shuttle (average orbit altitude of 330.35 km) for 12 days and 18.5 hours. A new generation of flies was reared in microgravity. In larvae, the immune system was examined by analyzing plasmatocyte number and activity in culture. In adults, the induced immune responses were analyzed by bacterial clearance and quantitative real-time polymerase chain reaction (qPCR) of selected genes following infection with E. coli. The RNA levels of relevant immune pathway genes were determined in both larvae and adults by microarray analysis. The ability of larval plasmatocytes to phagocytose E. coli in culture was attenuated following spaceflight, and in parallel, the expression of genes involved in cell maturation was downregulated. In addition, the level of constitutive expression of pattern recognition receptors and opsonins that specifically recognize bacteria, and of lysozymes, antimicrobial peptide (AMP) pathway and immune stress genes, hallmarks of humoral immunity, were also reduced in larvae. In adults, the efficiency of bacterial clearance measured in vivo following a systemic infection with E. coli post-flight, remained robust. We show that spaceflight altered both cellular and humoral immune responses in Drosophila and that the disruption occurs at multiple interacting pathways
A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)
Meeting abstrac
Diagnosis of primary pulmonary T- cell/histiocyte-rich large B cell lymphoma with tissue eosinophilia via clinicopathological observation and molecular assay
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