UCL University College London Eprints
UCL Eprints collects the work of UCL researchers and makes it freely available over the web, helping the worldwide scholarly community to discover UCL research. Institutional repositories like UCL Eprints complement the traditional academic publishing and scholarly communications processes. They raise the visibility of research and help to maximise its impact. UCL researchers are encouraged to deposit a copy of each journal article, conference paper, working paper, and any other research output, in the UCL Eprints at the earliest opportunity, ensuring that their research reaches as wide an audience as possible.
Frequency-difference electrical impedance tomography: Phantom imaging experiments - Ahn, S; Jun, SC; Seo, JK; Lee, J; Woo, EJ; Holder, D
Frequency-difference electrical impedance tomography (fdEIT) using a weighted voltage difference has been proposed as a means to provide images of admittivity changes at different frequencies. This weighted difference method is an effective way to extract anomaly information while eliminating background effects by unknown boundary geometry, uncertainty in electrode positions and other systematic measurement artefacts. It also properly handles the interplay between conductivity and permittivity in measured boundary voltage data. Though the proposed fdEIT algorithm is promising for applications such as detection of hemorrhagic stroke and breast cancer, more validation studies are needed. In this paper, we performed two-and three-dimensional numerical...
Update on the management of cholangiocarcinoma. - Skipworth, JR; Keane, MG; Pereira, SP
Cholangiocarcinoma (CC) is a rare cancer arising from the epithelium of the biliary tree, anywhere from the small peripheral hepatic ducts to the distal common bile duct. Classification systems for CC typically group tumours by anatomical location into intrahepatic, hilar or extrahepatic subtypes. Surgical resection or liver transplantation remains the only curative therapy for CC, but up to 80% of patients present with advanced, irresectable disease. Unresectable CC remains resistant to many chemotherapeutic agents, although gemcitabine, particularly in combination with other agents, has been shown to improve overall survival. Ongoing investigation of biological agents has also yielded some promising results....
Dissociable Processes for Orientation Discrimination Learning and Contextual Illusion Magnitude. - Wilks, CE; Rees, G; Schwarzkopf, DS
Previous research suggests an inverse relationship between human orientation discrimination sensitivity and tilt illusion magnitude. To test whether these perceptual functions are inherently linked, we measured both orientation discrimination sensitivity and the magnitude of the tilt illusion before and after participants had been trained for three days on an orientation discrimination task. Discrimination sensitivity improved with training and this improvement remained one month after the initial learning. However, tilt illusion magnitude remained unchanged before and after orientation training, at either trained or untrained orientations. Our results suggest that orientation discrimination sensitivity and illusion magnitude are not inherently linked. They also...
Model averaging, optimal inference, and habit formation. - FitzGerald, TH; Dolan, RJ; Friston, KJ
Postulating that the brain performs approximate Bayesian inference generates principled and empirically testable models of neuronal function-the subject of much current interest in neuroscience and related disciplines. Current formulations address inference and learning under some assumed and particular model. In reality, organisms are often faced with an additional challenge-that of determining which model or models of their environment are the best for guiding behavior. Bayesian model averaging-which says that an agent should weight the predictions of different models according to their evidence-provides a principled way to solve this problem. Importantly, because model evidence is determined by both the accuracy and...
Haploinsufficiency of the Insulin-Like Growth Factor-1 Receptor Enhances Endothelial Repair and Favorably Modifies Angiogenic Progenitor Cell Phenotype. - Yuldasheva, NY; Rashid, ST; Haywood, NJ; Cordell, P; Mughal, R; Viswambharan, H; Imrie, H; Sukumar, P; Cubbon, RM; Aziz, A; Gage, M; Mbonye, KA; Smith, J; Galloway, S; Skromna, A; Scott, DJ; Kearney, MT; Wheatcroft, SB
Defective endothelial regeneration predisposes to adverse arterial remodeling and is thought to contribute to cardiovascular disease in type 2 diabetes mellitus. We recently demonstrated that the type 1 insulin-like growth factor receptor (IGF1R) is a negative regulator of insulin sensitivity and nitric oxide bioavailability. In this report, we examined partial deletion of the IGF1R as a potential strategy to enhance endothelial repair.
Association between human papillomavirus vaccine status and other cervical cancer risk factors - Bowyer, HL; Dodd, RH; Marlow, LAV; Waller, J
Little is known about the relationship between HPV vaccine uptake and other risk factors for cervical cancer. This study aimed to measure the association between vaccine status and cervical cancer risk factors in adolescent girls. Girls (15-16 years) from the first two cohorts to be offered routine HPV vaccination in the NHS immunisation programme completed a survey 3 years post-vaccination. Recruitment took place at 13 schools in London. Of 2768 girls registered in Year 11, 1912 (69%) took part and provided analysable data. Questions assessed vaccine status, demographic characteristics, smoking status, sexual behaviour and intention to attend cervical screening. Overall,...
Facilitators and barriers to help-seeking for breast and cervical cancer symptoms: A qualitative study with an ethnically diverse sample in London - Marlow, LAV; McGregor, LM; Wardle, J; Nazroo, JY
Objective Earlier diagnosis of cancer has become a policy priority. There is evidence that minority ethnic groups are more likely to delay help-seeking for cancer symptoms, but few studies have explored reasons for delay in these groups. The present study explored facilitators and barriers to help-seeking for breast and cervical cancer in an ethnically diverse sample of women. Methods Semi-structured interviews were carried out with 54 healthy women from a range of ethnic backgrounds; Indian, Pakistani, Bangladeshi, Caribbean, African, Black British, Black other, White British and White other. Framework analysis was used to identify themes. Results Appraising a symptom as...
Health outcome after major trauma: what are we measuring? - Hoffman, K; Cole, E; Playford, ED; Grill, E; Soberg, HL; Brohi, K
Trauma is a global disease and is among the leading causes of disability in the world. The importance of outcome beyond trauma survival has been recognised over the last decade. Despite this there is no internationally agreed approach for assessment of health outcome and rehabilitation of trauma patients.
Sparse encoding of automatic visual association in hippocampal networks. - Hulme, OJ; Skov, M; Chadwick, M; Siebner, HR; Ramsøy, TZ
Intelligent action entails exploiting predictions about associations between elements of ones environment. The hippocampus and mediotemporal cortex are endowed with the network topology, physiology, and neurochemistry to automatically and sparsely code sensori-cognitive associations that can be reconstructed from single or partial inputs. Whilst acquiring fMRI data and performing an attentional task, participants were incidentally presented with a sequence of cartoon images. By assigning subjects a post-scan free-association task on the same images we assayed the density of associations triggered by these stimuli. Using multivariate Bayesian decoding, we show that human hippocampal and temporal neocortical structures host sparse associative representations that...