12,144 results on '"Martin, O."'
Search Results
152. Assistant Delivery Robot for Nursing Home using ROS: Robotic prototype for medicine delivery and vital signs registration.
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Jonatan E. Salinas-Avila, Hugo G. González-Hernández, Nashely Martinez-Chan, Carlos M. Bielma-Avendano, Ximena A. Salinas-Molar, and Martin O. Garcia-Garcia
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- 2022
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153. xGQA: Cross-Lingual Visual Question Answering.
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Jonas Pfeiffer, Gregor Geigle, Aishwarya Kamath, Jan-Martin O. Steitz, Stefan Roth 0001, Ivan Vulic, and Iryna Gurevych
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- 2022
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154. Animal Board Invited Review: Quantification of resilience in farm animals
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Taghipoor, M, Pastell, M, Martin, O, Nguyen ba, H, van Milgen, J, Doeschl-Wilson, A, Loncke, C, Friggens, NC, Puillet, L, and Muñoz-Tamayo, R
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- 2023
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155. Diagnostic features and management options for duodenal neuroendocrine neoplasms: a retrospective, multi-centre study
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Dalvinder Mandair, Lukasz Kamieniarz, Michail Pizanias, Martin O. Weickert, Akshay Narayan, Luke Furtado O’Mahony, Martyn Caplin, John Ramage, Andreas Prachalias, Rajaventhan Srirajaskanthan, and Christos Toumpanakis
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Medicine ,Science - Abstract
Abstract Duodenal neuroendocrine neoplasms (dNENs) are rare neoplasms but their incidence is on the rise. They are classified into 5 sub-types but there remains much heterogeneity in behaviour in particular of non-functioning dNENs. To retrospectively analyse outcomes for all types of dNENs, and highlight prognostic factors associated with worse outcome. 102 (57 m/45f.) patients were identified with mean age at diagnosis 62 (range 32–87) years. The majority were non-functioning tumours 87/102 and median size was 10 mm (range 0.9–130 mm). 83 patients had Stage I or II disease, of which 17 underwent endoscopic resection with R1 rate of 45% and complication rate 12%. 36 patients were kept under endoscopic surveillance. There were 11 deaths of which 4 were disease related. Age and Ki67 > 20% were associated with worse OS in all dNENs. In non-functioning dNENs Ki67 > 3% was a predictor of lymph nodes metastases with OR 18.2 (2.54–13) (p
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- 2022
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156. Applying precision medicine to the diagnosis and management of endocrine disorders
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Martin Bidlingmaier, Helena Gleeson, Ana-Claudia Latronico, and Martin O Savage
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adolescent ,biomarkers ,child ,early diagnosis ,endocrine diagnosis ,genetic testing ,growth hormone ,precocious puberty ,precision medicine ,transitional care ,Diseases of the endocrine glands. Clinical endocrinology ,RC648-665 - Abstract
Precision medicine employs digital tools and knowledge of a patient’s genetic makeup, environment and lifestyle to improve diagnostic accuracy and to develop individualised treatment and prevention strategies. Precision medicine has improved management in a number of disease areas, most notably in oncology, and it has the potential to positively impact others, including endocrine disorders. The accuracy of diagnosis in young patients with growth disorders can be improved by using biomarkers. Insulin-like growth factor I (IGF-I) is the most widely accepted biomarker of growth hormone secretion, but its predictive value for recombinant human growth hormone treatment response is modest and various factors can affect the accuracy of IGF-I measurement s. These factors need to be taken into account when considering IGF-I as a component of precision medicine in the management of growth hormone deficiency. The use of genetic anal yses can assist with diagnosis by confirming the aetiology, facilitate treatment deci sions, guide counselling and allow prompt intervention in children with pubertal disorders, such as central precocious puberty and testotoxicosis. Precision medicine has also proven useful during the transition of young people with endocrine disorders from paediatric to adult services when patients are at heightened risk of dropping out from medical care. An understanding of the likelihood of ongoing GH deficiency, using tools such as MRI, de tailed patient history and IGF-I levels, can assist in determining the need for continued recombinant human growth hormone treatment during the process of transitional care.
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- 2022
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157. Trend of Malaria Burden Among Residents of Kisii County, Kenya After More Than a Decade Usage of Artemisinin Combined Therapies, 11–Year Laboratory Based Retrospective Study
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Maniga JN, Samuel M, Rael M, Odda J, Martin O, Ntulume I, Bwogo P, Mfitundinda W, and Akinola SA
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malaria burden ,artemisinin combined therapies ,retrospective ,Infectious and parasitic diseases ,RC109-216 - Abstract
Josephat Nyabayo Maniga,1– 3 Mong’are Samuel,4 Masai Rael,1 John Odda,5,6 Odoki Martin,2,3 Ibrahim Ntulume,2,7 Pacifica Bwogo,1 Wilberforce Mfitundinda,3 Saheed Adekunle Akinola2,8 1Department of Biological Sciences, Kisii University, Kisii, Kenya; 2Department of Microbiology and Immunology, Kampala International University Western Campus, Bushenyi, Uganda; 3College of Medicine, Health and Life Sciences, School of Medicine, King Ceasor University, Kampala, Uganda; 4School of Health Sciences, Kisii University, Kisii, Kenya; 5School of Pharmacy, Kampala International University Western Campus, Bushenyi, Uganda; 6Department of Pharmacology and Therapeutics, Makerere University, Kampala, Uganda; 7School of Biosecurity, Biotechnical and Laboratory Science, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, Kampala, Uganda; 8Department of Clinical Biology, School of Medicine and Pharmacy, College of Medicine and Health Sciences, University of Rwanda, Butare, RwandaCorrespondence: Josephat Nyabayo Maniga, College of Medicine, Health and Life Sciences, School of Medicine, King Ceasor University, Kampala, Uganda, Tel +256750739527, Email josnyabayo@yahoo.comBackground: Malaria remains a major vector borne disease globally, with the majority of the casualties reported in Africa. Despite this fact, there is drastic reduction in malaria infection using Artemisinin combined therapies (ACTs). Malaria is characterized by significant inconsistency in different geographical locations due to different confounding factors. There is need to identify zone-specific malaria trends and interventions to completely eliminate the disease. Thus the study was aimed at assessing the 11-year trend of microscopically confirmed malaria cases in Kisii County, Kenya, so as to devise area-specific evidence-based interventions, informed decisions, and to track the effectiveness of malaria control programs.Methods: This was a retrospective study carried out to determine 11-year malaria trend rates centered on the admission and laboratory records from health facilities located at four Sub-Counties in Kisii County, Kenya. Parasitological positivity rates of malaria were determined by comparing with the register records in health facilities which recorded confirmed malaria cases with the total number of monthly admissions over the entire year. Data was analyzed by using descriptive tools and chi-square test.Results: There were 36,946 suspect cases, with 8449 (22.8%) confirmed malaria cases reported in this study. The overall malaria slide positivity rate over the last 11 years in the study area was 22.6%. The months of April and August showed the largest number of malaria cases (63%). The age group of ≥ 18 years contained the most positive confirmed cases, having a prevalence rate of 2953 (35.45%). Out of the confirmed malaria cases, 2379 (28.1%) were males and 6070 (71.9%) were females The highest malaria prevalence rate was recorded in 2014, with Marani Sub-County recording the highest positivity rate of 37.94%.Conclusion: From the observed trends, malaria prevalence and transmission still remains stable in the study area. Thus more interventions need to be scaled up.Keywords: malaria burden, artemisinin combined therapies, retrospective, ACTs
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- 2022
158. Antioxidants stimulate BACHI-dependent tumor angiogenesis
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Wang, Ting, Dong, Yongqiang, Huang, Zhiqiang, Zhang, Guoqing, Zhao, Ying, Yao, Haidong, Hu, Jianjiang, Tuksammel, Elin, Cai, Huan, Liang, Ning, Xu, Xiufeng, Yang, Xijie, Schmidt, Sarah, Qiao, Xi, Schlisio, Susanne, Stromblad, Staffan, Qian, Hong, Jiang, Changtao, Treuter, Eckardt, and Bergo, Martin O.
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Thermo Fisher Scientific Inc. ,Scientific equipment and supplies industry -- Genetic aspects ,Acetylcysteine ,Genes -- Genetic aspects ,Antioxidants ,Cancer -- Genetic aspects -- Development and progression ,Lung cancer -- Development and progression -- Genetic aspects ,Genetic transcription -- Genetic aspects ,DNA binding proteins -- Genetic aspects ,Health care industry - Abstract
Lung cancer progression relies on angiogenesis, which is a response to hypoxia typically coordinated by hypoxia- inducible transcription factors (HIFs), but growing evidence indicates that transcriptional programs beyond HIFs control tumor angiogenesis. Here, we show that the redox-sensitive transcription factor BTB and CNC homology 1 (BACH1) controls the transcription of a broad range of angiogenesis genes. BACH1 is stabilized by lowering ROS levels; consequently, angiogenesis gene expression in lung cancer cells, tumor organoids, and xenograft tumors increased substantially following administration of vitamins C and E and N-acetylcysteine in a BACH1-dependent fashion under normoxia. Moreover, angiogenesis gene expression increased in endogenous BACH1-overexpressing cells and decreased in SACH7-knockout cells in the absence of antioxidants. BACH1 levels also increased upon hypoxia and following administration of prolyl hydroxylase inhibitors in both HfF7A-knockout and WT cells. BACH1 was found to be a transcriptional target of HIF1[alpha], but BACH1's ability to stimulate angiogenesis gene expression was HIF1[alpha] independent. Antioxidants increased tumor vascularity in vivo in a BACH1- dependent fashion, and overexpressing BACH1 rendered tumors sensitive to antiangiogenesis therapy. BACH1 expression in tumor sections from patients with lung cancer correlated with angiogenesis gene and protein expression. We conclude that BACH1 is an oxygen- and redox-sensitive angiogenesis transcription factor., Introduction Lung tumor growth and metastasis requires angiogenesis--the formation of new blood vessels (1, 2). Angiogenesis is typically triggered by hypoxia, which stabilizes hypoxia-inducible transcription factors (HIFs) including HIF1[alpha] and [...]
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- 2023
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159. IGF-1 and IGFBP-1 as Possible Predictors of Response to Lifestyle Intervention—Results from Randomized Controlled Trials
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Meyer, Nina M. T., primary, Kabisch, Stefan, additional, Dambeck, Ulrike, additional, Honsek, Caroline, additional, Kemper, Margrit, additional, Gerbracht, Christiana, additional, Arafat, Ayman M., additional, Birkenfeld, Andreas L., additional, Schwarz, Peter E. H., additional, Machann, Jürgen, additional, Osterhoff, Martin A., additional, Weickert, Martin O., additional, and Pfeiffer, Andreas F. H., additional
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- 2024
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160. Application of plant extended phenotypes to manage the agricultural microbiome belowground
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Alonso Favela, Martin O. Bohn, and Angela D. Kent
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microbiome ,sustainability ,extended phenotypes ,regenerative agriculture ,plant breeding ,Microbial ecology ,QR100-130 - Abstract
Plants have a surprising capacity to alter their environmental conditions to create adequate niches for survival and stress tolerance. This process of environmental transformation, commonly referred to as “extended phenotypes” or “niche construction”, has historically been studied in the domain of ecology, but this is a process that is pervasive across the plant kingdom. Furthermore, research is beginning to show that plants’ extended phenotypes shape the assembly and function of closely associated microbial communities. Incorporation and understanding the role that plant-extended phenotypes play in agriculture may offer novel, bioinspired methods to manage our arable soil microbiomes. Here, we review the challenges agriculture faces, the plant extended phenotypes we know to shape the microbiome, and the potential utilization of this knowledge to improve the environmental impact of agriculture. Understanding how plant extended phenotypes shape microbial communities could be a key to creating a sustainable future with both plants and microbiomes in consideration.
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- 2023
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161. Early Mediterranean-Based Nutritional Intervention Reduces the Rate of Gestational Diabetes Mellitus in Overweight and Obese Pregnant Women: A Post-Hoc Analysis of the San Carlos Gestational Prevention Study
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Martin-O´Connor, Rocio, primary, Ramos-Leví, Ana M., additional, Melero, Verónica, additional, Arnoriaga-Rodríguez, María, additional, Barabash, Ana, additional, Valerio, Johanna, additional, Del Valle, Laura, additional, De Miguel Novoa, María Paz, additional, Díiaz, Angel, additional, Familiar, Cristina, additional, Moraga, Inmaculada, additional, Durán, Alejandra, additional, Cuesta, Martín, additional, Torrejón, Maria Jose, additional, Martinez-Novillo, Mercedes, additional, Marcuello, Clara, additional, Pazos, Mario, additional, Rubio-Herrera, Miguel Ángel, additional, Matía-Martín, Pilar, additional, and Calle-Pascual, Alfonso Luis, additional
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- 2024
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162. Assessing cardiovascular stress based on heart rate variability in female shift workers: a multiscale-multifractal analysis approach
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Delgado-Aranda, Raquel, primary, Dorantes-Méndez, Guadalupe, additional, Bianchi, Anna Maria, additional, Kortelainen, Juha M., additional, Coelli, Stefania, additional, Jimenez-Cruz, Jorge, additional, and Méndez, Martin O., additional
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- 2024
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163. IGF-1 and IGFBP-1, Possible Predictors of Response to Lifestyle Intervention – Results from Randomized Controlled Trials
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Meyer, Nina M.T., primary, Kabisch, Stefan, additional, Dambeck, Ulrike, additional, Honsek, Caroline, additional, Kemper, Margrit, additional, Gerbracht, Christiana, additional, Arafat, Ayman M., additional, Birkenfeld, Andreas L., additional, Schwarz, Peter E. H., additional, Machann, Jürgen, additional, Osterhoff, Martin A., additional, Weickert, Martin O., additional, and Pfeiffer, Andreas F. H., additional
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- 2024
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164. Evolving growth hormone deficiency: proof of concept
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Chimatapu, Sri Nikhita, primary, Sethuram, Swathi, additional, Samuels, Julie G., additional, Klomhaus, Alexandra, additional, Mintz, Cassie, additional, Savage, Martin O., additional, and Rapaport, Robert, additional
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- 2024
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165. Multi-view X-ray R-CNN
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Steitz, Jan-Martin O., Saeedan, Faraz, and Roth, Stefan
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Computer Science - Computer Vision and Pattern Recognition - Abstract
Motivated by the detection of prohibited objects in carry-on luggage as a part of avionic security screening, we develop a CNN-based object detection approach for multi-view X-ray image data. Our contributions are two-fold. First, we introduce a novel multi-view pooling layer to perform a 3D aggregation of 2D CNN-features extracted from each view. To that end, our pooling layer exploits the known geometry of the imaging system to ensure geometric consistency of the feature aggregation. Second, we introduce an end-to-end trainable multi-view detection pipeline based on Faster R-CNN, which derives the region proposals and performs the final classification in 3D using these aggregated multi-view features. Our approach shows significant accuracy gains compared to single-view detection while even being more efficient than performing single-view detection in each view., Comment: To appear at the 40th German Conference on Pattern Recognition (GCPR) 2018
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- 2018
166. Focal plane $C_n^2(h)$ profiling based on single conjugate adaptive optics compensated images
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Beltramo-Martin, O., Correia, C. M., Neichel, B., and Fusco, T.
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Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
Knowledge of the atmospheric turbulence in the telescope line-of-sight is crucial for wide-field observations assisted by adaptive optics (AO), for which the Point Spread Function (PSF) becomes strongly elongated due to the anisoplanatism effect. This one must be modelled accurately to extrapolate the PSF anywhere across the Field of view (FOV) and improve the science exploitation. However, anisoplanatism is a function of the Cn2(h) profile, that is not directly accessible from single conjugate AO telemetry. One may rely on external profilers, but recent studies have highlighted more than 10% of discrepancies with AO internal measurements, while we aim better than 1% of accuracy for PSF modelling. To tackle this existing limitation, we present the Focal plane profiling (FPP), as a $C_n^2(h)$ profiling method that relies on post-AO focal plane images. We demonstrate such an approach complies with a 1%-level of accuracy on the $C_n^2(h)$ estimation and establish how this accuracy varies regarding the calibration stars magnitudes and positions in the field. We highlight that photometry and astrometry errors due to PSF mis-modelling reaches respectively 1% and 50{\mu}as using FPP on a Keck baseline, with a preliminary calibration using a star of magnitude H=14 at 20". We also validate this concept using Canadas NRC-Herzberg HENOS testbed images in comparing FPP retrieval with alternative $C_n^2(h)$ measurements on HeNOS. The FPP approach allows to profile the $C_n^2(h)$ using the SCAO systems and improve significantly the PSF characterisation. Such a methodology is also ELT-size compliant and will be extrapolated to tomographic systems in a near future.
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- 2018
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167. Optical spectroscopy of local type-1 AGN LINERs
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Cazzoli, S., Marquez, I., Masegosa, J., del Olmo, A., Povic, M., Gonzalez-Martin, O., Balmaverde, B., Hernandez-Garcia, L., and Garcia-Burillo, S.
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Astrophysics - Astrophysics of Galaxies - Abstract
The Balmer emission originated in the broad line region (BLR) of active galactic nuclei (AGNs) could be either weak and difficult to detect, or even absent, for low luminosity AGNs, as LINERs. Our goals in this paper are threefold. First, we want to explore the AGN-nature of nearby type-1 LINERs. Second, we aim at deriving a reliable interpretation for the different components of emission lines by studying their kinematics and ionization mechanism. Third, we intend to probe the neutral gas in the nuclei of these LINERs. We study the 22 local (z<0.025) type-1 LINERs from the Palomar Survey, on the basis of optical ground- and space-based long-slit spectroscopic observations taken with TWIN/CAHA and ALFOSC/NOT. Kinematics and fluxes of a set of emission lines, from H{\beta} to [S II], and the NaD doublet in absorption have been modelled and measured, after the subtraction of the underlying starlight. We also use ancillary spectroscopic data from HST/STIS. We found that the broad H{\alpha} component is sometimes elusive in our ground-based spectroscopy whereas it is ubiquitous for space-based data. By combining optical diagnostic diagrams, theoretical models (for AGNs, pAGB-stars and shocks) and the weak/strong-[O I] classification, we exclude the pAGBs-stars scenario in favor of the AGN as the dominant mechanism of ionisation in these LINERs, being shocks however relevant. The kinematical properties of the emission lines may indicate the presence of ionized outflows, preferentially seen in [O I]. However, the neutral gas outflows, diagnosed by NaD, would appear to be less frequent., Comment: 61 pages, 10 Figures, 8 Tables, 2 Appendices
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- 2018
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168. The origin of the mid-infrared nuclear polarization of active galactic nuclei
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Lopez-Rodriguez, E., Alonso-Herrero, A., Diaz-Santos, T., Gonzalez-Martin, O., Ichikawa, K., Levenson, N. A., Martinez-Paredes, M., Nikutta, R., Packham, C., Perlman, E., Almeida, C. Ramos, Rodriguez-Espinosa, J. M., and Telesco, C. M.
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Astrophysics - Astrophysics of Galaxies - Abstract
We combine new (NGC 1275, NGC 4151, and NGC 5506) and previously published (Cygnus A, Mrk 231, and NGC 1068) sub-arcsecond resolution mid-infrared (MIR; 8-13 $\mu$m) imaging- and spectro-polarimetric observations of six Seyfert galaxies using CanariCam on the 10.4-m Gran Telescopio CANARIAS. These observations reveal a diverse set of physical processes responsible for the nuclear polarization, and permit characterization of the origin of the MIR nuclear polarimetric signature of active galactic nuclei (AGN). For all radio quiet objects, we found that the nuclear polarization is low (<1 per cent), and the degree of polarization is often a few per cent over extended regions of the host galaxy where we have sensitivity to detect such extended emission (i.e., NGC 1068 and NGC 4151). We suggest that the higher degree of polarization previously found in lower resolution data arises only on the larger-than-nuclear scales. Only the radio-loud Cygnus A exhibits significant nuclear polarization ($\sim$11 per cent), attributable to synchrotron emission from the pc-scale jet close to the core. We present polarization models that suggest that the MIR nuclear polarization for highly obscured objects arises from a self-absorbed MIR polarized clumpy torus and/or dichroism from the host galaxy, while for unabsorbed cores, MIR polarization arises from dust scattering in the torus and/or surrounding nuclear dust., Comment: 9 pages, 4 figures. Accepted to MNRAS
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- 2018
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169. Modelling dust rings in early-type galaxies through a sequence of radiative transfer simulations and 2D image fitting
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Bonfini, P., Gonzalez-Martin, O., Fritz, J., Bitsakis, T., Bruzual, G., and Sodi, B. Cervantes
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Astrophysics - Astrophysics of Galaxies - Abstract
A large fraction of early-type galaxies (ETGs) host prominent dust features, and central dust rings are arguably the most interesting among them. We present here `Lord Of The Rings' (LOTR), a new methodology which allows to integrate the extinction by dust rings in a 2D fitting modelling of the surface brightness distribution. Our pipeline acts in two steps, first using the surface fitting software GALFIT to determine the unabsorbed stellar emission, and then adopting the radiative transfer code SKIRT to apply dust extinction. We apply our technique to NGC 4552 and NGC 4494, two nearby ETGs. We show that the extinction by a dust ring can mimic, in a surface brightness profile, a central point source (e.g. an unresolved nuclear stellar cluster or an active galactic nucleus; AGN) superimposed to a `core' (i.e. a central flattening of the stellar light commonly observed in massive ETGs). We discuss how properly accounting for dust features is of paramount importance to derive correct fluxes especially for low luminosity AGNs (LLAGNs). We suggest that the geometries of dust features are strictly connected with how relaxed is the gravitational potential, i.e. with the evolutionary stage of the host galaxy. Additionally, we find hints that the dust mass contained in the ring relates to the AGN activity., Comment: Accepted in MNRAS
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- 2018
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170. Off-axis point spread function characterisation in laser-guide star adaptive optics systems
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Beltramo-Martin, O., Correia, C. M., Mieda, E., Neichel, B., Fusco, T., Witzel, G., Lu, J., and Véran, J. -P.
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Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
Adaptive optics (AO) restore the angular resolution of ground-based telescopes, but at the cost of delivering a time- and space-varying point spread function (PSF) with a complex shape. PSF knowledge is crucial for breaking existing limits on the measured accuracy of photometry and astrometry in science observations. In this paper, we concentrate our analyses on anisoplanatism signature only onto PSF: for large-field observations (20") with single- conjugated AO, PSFs are strongly elongated due to anisoplanatism that manifests itself as three different terms for Laser-guide star (LGS) systems: angular, focal and tilt. We propose a generalized model that relies on a point-wise decomposition of the phase and encompasses the non-stationarity of LGS systems. We demonstrate it is more accurate and less computationally demanding than existing models: it agrees with end-to-end physical-optics simulations to within 0.1% of PSF measurables, such as Strehl-ratio, FWHM and fraction of variance unexplained.Secondly, we study off-axis PSF modelling is with respect to $C_n^2(h)$ profile (heights and fractional weights). For 10m class telescope, PSF morphology is estimated at 1% level as long as we model the atmosphere with at least 7 layers whose heights and weights are known respectively with 200m and 10% precision. As a verification test we used the Canada's NRC-Herzberg HeNOS testbed data, featuring four lasers. We highlight capability of retrieving off-axis PSF characteristics within 10% of fraction of variance unexplained, which complies with the expected range from the sensitivity analysis. Our new off-axis PSF modelling method lays the ground-work for testing on-sky in the near future.
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- 2018
171. Resolving the nuclear obscuring disk in the Compton-thick Seyfert galaxy NGC5643 with ALMA
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Alonso-Herrero, A., Pereira-Santaella, M., García-Burillo, S., Davies, R. I., Combes, F., Asmus, D., Bunker, A., Díaz-Santos, T., Gandhi, P., González-Martín, O., Hernán-Caballero, A., Hicks, E., Hönig, S., Labiano, A., Levenson, N. A., Packham, C., Almeida, C. Ramos, Ricci, C., Rigopoulou, D., Rosario, D., Sani, E., and Ward, M. J.
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Astrophysics - Astrophysics of Galaxies - Abstract
We present ALMA Band 6 $^{12}$CO(2--1) line and rest-frame 232GHz continuum observations of the nearby Compton-thick Seyfert galaxy NGC5643 with angular resolutions 0.11-0.26arcsec (9-21pc). The CO(2--1) integrated line map reveals emission from the nuclear and circumnuclear region with a two-arm nuclear spiral extending 10arcsec on each side. The circumnuclear CO(2--1) kinematics can be fitted with a rotating disk, although there are regions with large residual velocities and/or velocity dispersions. The CO(2--1) line profiles of these regions show two different velocity components. One is ascribed to the circular component and the other to the interaction of the AGN outflow, as traced by the [O III]5007AA emission, with molecular gas in the disk a few hundred parsecs from the AGN. On nuclear scales, we detected an inclined CO(2--1) disk (diameter 26 pc, FWHM) oriented almost in a north-south direction. The CO(2--1) nuclear kinematics can be fitted with a rotating disk which appears to be tilted with respect to the large scale disk. There are strong non-circular motions in the central 0.2-0.3 arcsec with velocities of up to 110km/s. In the absence of a nuclear bar, these motions could be explained as radial outflows in the nuclear disk. We estimate a total molecular gas mass for the nuclear disk of $M({\rm H}_2)=1.1\times 10^7\,M_\odot$ and an H$_2$ column density toward the location of the AGN of $N({\rm H}_2)\sim 5 \times 10^{23}\,{\rm cm}^{-2}$, for a standard CO-to-H$_2$ conversion factor. We interpret this nuclear molecular gas disk as the obscuring torus of NGC5643 as well as the collimating structure of the ionization cone., Comment: 16 papes, 9 figures. Accepted to ApJ. Updated Fig.4
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- 2018
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172. Update on the X-ray variability plane for active galactic nuclei: The role of the obscuration
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González-Martín, O.
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Astrophysics - Astrophysics of Galaxies ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
Scaling relations are the most powerful astrophysical tools to set constraints to the physical mechanisms of astro- nomical sources and to infer properties that cannot be accessed directly. We re-investigate here one of these scaling relations in active galactic nuclei (AGN); the so-called X-ray variability plane (or mass-luminosity-timescale relation, McHardy et al. 2006). This relation links the power-spectral density (PSD) break frequency with the super-massive black hole (SMBH) mass and the bolometric luminosity. We used available XMM -Newton observations of a sample of 22 AGN to study the PSD and spectra in short segments within each observation. This allows us to report for the first time that the PSD break frequency varies for each object, showing variations in 19 out of the 22 AGN analyzed. Our analysis of the variability plane confirms the relation between the break frequency and the SMBH mass and finds that the obscuration along the line of sight NH (or the variations on the obscuration using its standard deviation, $\rm{\Delta}$(NH)) is also a required parameter, at least for the range of frequencies analyzed here (3x10E-5-5x10E-2Hz). We constrain a new variability plane of the form: log($\nu_{Break}$) = (-0.589$\rm{\pm}$0.005) log(MBH ) + (0.10$\rm{\pm}$0.01) log(NH ) - (1.5$\rm{\pm}$0.3) (or log($\nu_{Break}$)=(-0.549$\rm{\pm}$0.009)log(MBH)+(0.56$\rm{\pm}$0.06)$\rm{\Delta}$(NH)+(0.19$\rm{\pm}$0.08)). The X-ray variability plane found by McHardy et al. (2006) is roughly recovered when we use unobscured segments. We speculate that this behavior is well explained if most of the reported frequencies are related to inner clouds (within 1pc), following Kepler orbits under the gravitational field of the SMBH., Comment: 15 pages, 5 figures, 3 tables, accepted for publication in ApJ
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- 2018
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173. A possible binary AGN in Mrk\,622?
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Benítez, E., Rodríguez-Espinosa, J. M., Cruz-González, I., González-Martín, O., Negrete, C. A., Ruschel-Dutra, D., Gutiérrez, L., and Jiménez-Bailón, E.
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Astrophysics - Astrophysics of Galaxies - Abstract
Mrk\,622 is a Compton Thick AGN and a double-peaked narrow emission line galaxy, thus a dual AGN candidate. In this work, new optical long-slit spectroscopic observations clearly show that this object is rather a triple peaked narrow emission line galaxy, with both blue and red shifted narrow emission lines, as well as a much narrower emission line centred at the host galaxy systemic velocity. The average velocity offset between the blue and red shifted components is $\sim$500 km\,s$^{-1}$, which is producing the apparent double-peaked emission lines. These two components are in the loci of AGN in the Baldwin, Phillips \& Terlevich (BPT) diagrams and are found to be spatially separated by $\sim$76 pc. Analysis of the optical spatially resolved spectroscopic observations presented in this work favours that Mrk\,622 is a system consisting of a Composite AGN amidst a binary AGN candidate, likely the result of a recent merger. This notwithstanding, outflows from a starburst, or single AGN could also explain the triple nature of the emission lines., Comment: 5 pages, 3 figures, 3 tables. Accepted in MNRAS Letters. 5 pages, 3 tables, 3 figures
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- 2017
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174. Methodological consensus on clinical proton MRS of the brain: Review and recommendations.
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Wilson, Martin, Andronesi, Ovidiu, Barker, Peter B, Bartha, Robert, Bizzi, Alberto, Bolan, Patrick J, Brindle, Kevin M, Choi, In-Young, Cudalbu, Cristina, Dydak, Ulrike, Emir, Uzay E, Gonzalez, Ramon G, Gruber, Stephan, Gruetter, Rolf, Gupta, Rakesh K, Heerschap, Arend, Henning, Anke, Hetherington, Hoby P, Huppi, Petra S, Hurd, Ralph E, Kantarci, Kejal, Kauppinen, Risto A, Klomp, Dennis WJ, Kreis, Roland, Kruiskamp, Marijn J, Leach, Martin O, Lin, Alexander P, Luijten, Peter R, Marjańska, Małgorzata, Maudsley, Andrew A, Meyerhoff, Dieter J, Mountford, Carolyn E, Mullins, Paul G, Murdoch, James B, Nelson, Sarah J, Noeske, Ralph, Öz, Gülin, Pan, Julie W, Peet, Andrew C, Poptani, Harish, Posse, Stefan, Ratai, Eva-Maria, Salibi, Nouha, Scheenen, Tom WJ, Smith, Ian CP, Soher, Brian J, Tkáč, Ivan, Vigneron, Daniel B, and Howe, Franklyn A
- Subjects
Brain ,Humans ,Protons ,Magnetic Resonance Imaging ,Consensus ,MRS ,brain ,consensus ,metabolites ,semi-LASER ,shimming ,Biomedical Imaging ,4.1 Discovery and preclinical testing of markers and technologies ,Detection ,screening and diagnosis ,Biomedical Engineering ,Nuclear Medicine & Medical Imaging - Abstract
Proton MRS (1 H MRS) provides noninvasive, quantitative metabolite profiles of tissue and has been shown to aid the clinical management of several brain diseases. Although most modern clinical MR scanners support MRS capabilities, routine use is largely restricted to specialized centers with good access to MR research support. Widespread adoption has been slow for several reasons, and technical challenges toward obtaining reliable good-quality results have been identified as a contributing factor. Considerable progress has been made by the research community to address many of these challenges, and in this paper a consensus is presented on deficiencies in widely available MRS methodology and validated improvements that are currently in routine use at several clinical research institutions. In particular, the localization error for the PRESS localization sequence was found to be unacceptably high at 3 T, and use of the semi-adiabatic localization by adiabatic selective refocusing sequence is a recommended solution. Incorporation of simulated metabolite basis sets into analysis routines is recommended for reliably capturing the full spectral detail available from short TE acquisitions. In addition, the importance of achieving a highly homogenous static magnetic field (B0 ) in the acquisition region is emphasized, and the limitations of current methods and hardware are discussed. Most recommendations require only software improvements, greatly enhancing the capabilities of clinical MRS on existing hardware. Implementation of these recommendations should strengthen current clinical applications and advance progress toward developing and validating new MRS biomarkers for clinical use.
- Published
- 2019
175. The Changing Face of Paediatric Human Growth Hormone Therapy
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Martin O. Savage
- Subjects
growth ,growth hormone ,adherence ,safety ,immunogenicity ,Diseases of the endocrine glands. Clinical endocrinology ,RC648-665 - Abstract
Human growth hormone (hGH) has been used therapeutically to promote growth in children for over 60 years. Pituitary-extracted hGH has demonstrated positive growth promotion since the early 1960s. In 1985, prion-induced contamination of hGH triggered a global epidemic of Creutzfeldt–Jakob disease that was responsible for its discontinuation. Recombinant hGH immediately replaced pituitary hGH and, being available in large amounts, was used and licenced for therapy in GH-deficient children, followed by approval for non-GH deficient disorders such as Turner syndrome, short stature related to birth size small for gestational age, idiopathic short stature, SHOX deficiency, Prader–Willi syndrome and Noonan syndrome. RhGH therapy was refined by the use of growth prediction models; however, unmet needs, such as the variability in response and non-adherence resulted in the development of long-acting rhGH (LArhGH) molecules, which are currently in clinical trials and have shown non-inferiority in comparison with daily rhGH. It is likely that LArhGH will enter clinical practice in 2022 and 2023 and will need to demonstrate safety in terms of immunogenicity, IGF-1 generation, metabolic status and tolerability of potential injection pain and local reactions.
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- 2022
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176. Transient expression of an adenine base editor corrects the Hutchinson-Gilford progeria syndrome mutation and improves the skin phenotype in mice
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Daniel Whisenant, Kayeong Lim, Gwladys Revêchon, Haidong Yao, Martin O. Bergo, Piotr Machtel, Jin-Soo Kim, and Maria Eriksson
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Science - Abstract
Base editing to treat diseases is progressing but tissue delivery and progenitor cells correction are challenging. Here, the authors show sustained effects and propagation of mutation-corrected progenitors by transient adenine base editor expression, improving the skin phenotype of HGPS mice.
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- 2022
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177. The long noncoding RNA ADIPINT regulates human adipocyte metabolism via pyruvate carboxylase
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Alastair G. Kerr, Zuoneng Wang, Na Wang, Kelvin H. M. Kwok, Jutta Jalkanen, Alison Ludzki, Simon Lecoutre, Dominique Langin, Martin O. Bergo, Ingrid Dahlman, Carsten Mim, Peter Arner, and Hui Gao
- Subjects
Science - Abstract
Adipocyte-expressed long non-coding RNAs (lncRNAs) have been shown to regulate the transcription of genes involved in lipid metabolism. Here the authors describe a human adipocyte-specific lncRNA, ADIPINT, which regulates lipid metabolism in white adipocytes in part through its interaction with the metabolic enzyme pyruvate carboxylase.
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- 2022
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178. Automatic detection of A-phase onsets based on convolutional neural networks
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Mendez, Martin O., Arce-Santana, Edgar R., Alba, Alfonso, Arce-Guevara, Valdemar, Murguía-Ibarra, José S., and Bianchi, Anna M.
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- 2022
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179. Using [formula omitted]-Plume geothermal (CPG) energy technologies to support wind and solar power in renewable-heavy electricity systems
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Van Brummen, Anna C., Adams, Benjamin M., Wu, Raphael, Ogland-Hand, Jonathan D., and Saar, Martin O.
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- 2022
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180. Development of an artificial intelligence system to identify hypoglycaemia via ECG in adults with type 1 diabetes: protocol for data collection under controlled and free-living conditions
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Martin O Weickert, Thomas M Barber, Owain Cisuelo, Katy Stokes, Iyabosola B Oronti, Muhammad Salman Haleem, Leandro Pecchia, and John Hattersley
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Medicine - Abstract
Introduction Hypoglycaemia is a harmful potential complication in people with type 1 diabetes mellitus (T1DM) and can be exacerbated in patients receiving treatment, such as insulin therapies, by the very interventions aiming to achieve optimal blood glucose levels. Symptoms can vary greatly, including, but not limited to, trembling, palpitations, sweating, dry mouth, confusion, seizures, coma, brain damage or even death if untreated. A pilot study with healthy (euglycaemic) participants previously demonstrated that hypoglycaemia can be detected non-invasively with artificial intelligence (AI) using physiological signals obtained from wearable sensors. This protocol provides a methodological description of an observational study for obtaining physiological data from people with T1DM. The aim of this work is to further improve the previously developed AI model and validate its performance for glycaemic event detection in people with T1DM. Such a model could be suitable for integrating into a continuous, non-invasive, glucose monitoring system, contributing towards improving surveillance and management of blood glucose for people with diabetes.Methods and analysis This observational study aims to recruit 30 patients with T1DM from a diabetes outpatient clinic at the University Hospital Coventry and Warwickshire for a two-phase study. The first phase involves attending an inpatient protocol for up to 36 hours in a calorimetry room under controlled conditions, followed by a phase of free-living, for up to 3 days, in which participants will go about their normal daily activities unrestricted. Throughout the study, the participants will wear wearable sensors to measure and record physiological signals (eg, ECG and continuous glucose monitor). Data collected will be used to develop and validate an AI model using state-of-the-art deep learning methods.Ethics and dissemination This study has received ethical approval from National Research Ethics Service (ref: 17/NW/0277). The findings will be disseminated via peer-reviewed journals and presented at scientific conferences.Trial registration number NCT05461144.
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- 2023
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181. ROS-lowering doses of vitamins C and A accelerate malignant melanoma metastasis
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Muhammad Kashif, Haidong Yao, Sarah Schmidt, Xue Chen, Michelle Truong, Elin Tüksammel, Yiran Liu, and Martin O. Bergo
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Medicine (General) ,R5-920 ,Biology (General) ,QH301-705.5 - Abstract
Oxidative stress is a barrier of migration and metastasis for malignant melanoma cells. Consequently, reducing oxidative stress with the antioxidant N-acetylcysteine (NAC) stimulates melanoma cell migration in vitro and metastasis in vivo. However, it is not yet known whether the NAC effect is shared with other antioxidants. Here, we screened 104 redox-active compounds and identify 27 that increase migration of human malignant melanoma cells in two doses. Validation experiments in four cell lines and four drug doses resulted in a list of 18 compounds which were ranked based on their ability to increase migration and reduce ROS levels; vitamin C (VitC) ranked as number one, followed by the vitamin E analogue Trolox and several carotenoids and Vitamin A–related compounds. Four diet-relevant compounds from this list—VitC, β-carotene, retinyl palmitate, and canthaxanthin—were selected and found to accelerate metastasis in mice with BRAFV600E-driven malignant melanoma. Genomics analyses revealed that the transcription factor BACH1 is activated following antioxidant administration and knockout of Bach1 in mouse melanoma cells reduced lymph node and liver metastasis in xenograft mouse models. We conclude that a broad range of antioxidants accelerate melanoma migration and metastasis and that BACH1 is functionally linked to melanoma metastasis in vivo.
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- 2023
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182. Twenty-five year experience with aortic valve-sparing root replacement in a single teaching center
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Juri Sromicki, Mathias Van Hemelrijck, Martin O. Schmiady, Matthias Greutmann, Francesca Bonassin Tempesta, Carlos-A. Mestres, Paul R. Vogt, Thierry P. Carrel, and Tomáš Holubec
- Subjects
aortic valve sparing surgery ,aortic root reimplantation ,aortic regurgitation (AR) ,aortic aneurysm (AA) ,David operation and David procedure ,david operation ,Diseases of the circulatory (Cardiovascular) system ,RC666-701 - Abstract
ObjectivesAortic valve-sparing root replacement (AVSRR) is a technically demanding procedure. In experienced centers it offers excellent short- and long-term results, making the procedure an attractive alternative for aortic root replacement especially in young patients. The aim of this study was to analyze long-term results of AVSRR using the David operation in our institution over the last 25 years.MethodsThis is a single-center retrospective analysis of outcomes of David operations performed in a teaching institution not running a large AVSRR-program. Pre-, intra- and postoperative data were collected from the institutional electronic medical record system. Follow-up data were collected through direct contact of the patients and their cardiologists/primary care physicians.ResultsBetween 02/1996 and 11/2019, 131 patients underwent David operation in our institution by a total of 17 different surgeons. Median age was 48 (33–59), 18% were female. Elective surgery was performed in 89% of the cases, 11% were operated as emergency in the setting of an acute aortic dissection. Connective tissue disease was present in 24% and 26% had a bicuspid aortic valve. At hospital admission 61% had aortic regurgitation grade ≥3, 12% were in functional NYHA-class ≥III. 30-day mortality was 2%, 97% of the patients were discharged with aortic regurgitation ≤2. In 10-year follow-up, 15 (12%) patients had to be re-operated because of root-related complications. Seven patients (47%) received a transcatheter aortic valve implantation, 8 (53%) required surgical replacement of the aortic valve or a Bentall-De Bono operation. Estimated reoperation-free survival at 5 and 10 years was 93.5% ± 2.4% and 87.0% ± 3.5%, respectively. Subgroup analysis showed no differences in reoperation-free survival for patients presenting with a bicuspid valve or preoperative aortic regurgitation ≥3. However a preoperative left ventricular end diastolic diameter of ≥5.5 cm was associated with worse outcome.ConclusionDavid operations can be performed with excellent perioperative and 10-year follow-up outcomes in centers not running large AVSRR-programs.
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- 2023
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183. Cuisine in transition? Organic residue analysis of domestic containers from 9th-14th century Sicily
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Jasmine Lundy, Lea Drieu, Paola Orecchioni, Antonino Meo, Veronica Aniceti, Girolamo Fiorentino, Milena Primavera, Helen Talbot, Alessandra Molinari, Martin O. H. Carver, and Oliver E. Craig
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archaeology ,medieval Sicily ,organic residue analysis ,cuisine ,ceramics ,Science - Abstract
From the 9th to 14th centuries AD, Sicily experienced a series of rapid and quite radical changes in political regime, but the impact of these regime changes on the lives of the people that experienced them remains largely elusive within the historical narrative. We use a multi-faceted lipid residue approach to give direct chemical evidence of the use of 248 everyday domestic ceramic containers from Islamic and post-Islamic contexts in western Sicily to aid our understanding of daily habits throughout this period of political change. A range of commodities was successfully identified, including animal fats, vegetable products, fruit products (potentially including wine) and plant resins. The study highlights the complexity of residues in early medieval Mediterranean society as, in many cases, mixtures of commodities were observed reflecting sequential cooking events and/or the complex mixtures reflective of medieval recipes. However, overall, there were no clear changes in the composition of the residues following the imposition of Norman control over the island and through subsequent periods, despite some differences between urban centres and rural sites. Thus, lending to the idea that post-Islamic populations largely flourished and benefited from the agricultural systems, resources and recipes left by their predecessors.
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- 2023
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184. Shear induced fluid flow path evolution in rough-wall fractures: A particle image velocimetry examination
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Naets, Isamu, Ahkami, Mehrdad, Huang, Po-Wei, Saar, Martin O., and Kong, Xiang-Zhao
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- 2022
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185. Accelerated reactive transport simulations in heterogeneous porous media using Reaktoro and Firedrake
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Kyas, Svetlana, Volpatto, Diego, Saar, Martin O., and Leal, Allan M. M.
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- 2022
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186. A Nonlinear Formulation of Radiation Stress and Applications to Cnoidal Shoaling
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Paulsen, Martin O. and Kalisch, Henrik
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- 2022
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187. Impaired phosphocreatine metabolism in white adipocytes promotes inflammation
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Maqdasy, Salwan, Lecoutre, Simon, Renzi, Gianluca, Frendo-Cumbo, Scott, Rizo-Roca, David, Moritz, Thomas, Juvany, Marta, Hodek, Ondrej, Gao, Hui, Couchet, Morgane, Witting, Michael, Kerr, Alastair, Bergo, Martin O., Choudhury, Robin P., Aouadi, Myriam, Zierath, Juleen R., Krook, Anna, Mejhert, Niklas, and Rydén, Mikael
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- 2022
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188. Image Reconstruction in Light-Sheet Microscopy: Spatially Varying Deconvolution and Mixed Noise.
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Bogdan Toader, Jérôme Boulanger, Yury Korolev, Martin O. Lenz, James Manton, Carola-Bibiane Schönlieb, and Leila Muresan
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- 2022
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189. Diagnostic features and management options for duodenal neuroendocrine neoplasms: a retrospective, multi-centre study
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Mandair, Dalvinder, Kamieniarz, Lukasz, Pizanias, Michail, Weickert, Martin O., Narayan, Akshay, O’Mahony, Luke Furtado, Caplin, Martyn, Ramage, John, Prachalias, Andreas, Srirajaskanthan, Rajaventhan, and Toumpanakis, Christos
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- 2022
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190. Transient expression of an adenine base editor corrects the Hutchinson-Gilford progeria syndrome mutation and improves the skin phenotype in mice
- Author
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Whisenant, Daniel, Lim, Kayeong, Revêchon, Gwladys, Yao, Haidong, Bergo, Martin O., Machtel, Piotr, Kim, Jin-Soo, and Eriksson, Maria
- Published
- 2022
- Full Text
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191. The long noncoding RNA ADIPINT regulates human adipocyte metabolism via pyruvate carboxylase
- Author
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Kerr, Alastair G., Wang, Zuoneng, Wang, Na, Kwok, Kelvin H. M., Jalkanen, Jutta, Ludzki, Alison, Lecoutre, Simon, Langin, Dominique, Bergo, Martin O., Dahlman, Ingrid, Mim, Carsten, Arner, Peter, and Gao, Hui
- Published
- 2022
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192. Endoplasmic reticulum stress and the unfolded protein response in skeletal muscle of subjects suffering from peritoneal sepsis
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Metzing, Uta Barbara, von Loeffelholz, Christian, Steidl, Ricardo, Romeike, Bernd, Winkler, René, Rauchfuß, Falk, Settmacher, Utz, Stoppe, Christian, Coldewey, Sina M., Weinmann, Claudia, Weickert, Martin O., Claus, Ralf A., Birkenfeld, Andreas L., Kosan, Christian, and Horn, Paul
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- 2022
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193. Localising peacebuilding in South Sudan? : a case of transitional justice and reconciliation
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Agwella, Martin O. L.
- Subjects
303.6 ,Localising ,Peacebuilding ,Transitional justice ,Reconciliation ,South Sudan - Abstract
Despite the signing of the 2005 Sudan Comprehensive Peace Agreement that ended the two decades of South-North Sudan war; and the 2015 Agreement on the Resolution of the Conflict in South Sudan, to end the current civil war, armed conflicts persist in South Sudan. Two key inadequacies of the liberal peacebuilding model, applied to address modern conflicts in Africa and across the globe are its insistence on international justice instruments such as the International Criminal Court, and the failure to recognize the role of local approaches and to incorporate them into peacebuilding intervention policies. This has resulted in failures to address the grievances and bitterness of war affected people and to reconcile divided communities. This study examines the potential and limits of applying local approaches to post-conflict peacebuilding in South Sudan. Based on empirical data obtained through qualitative case study conducted in South Sudan over five months in 2016, the findings reveal that despite the wide use of local institutions and justice mechanisms, many challenges exist, that pose serious difficulties in solely applying these strategies to transitional justice. However, for the liberal peacebuilding model to address the root causes of internal conflicts and build sustainable peace, local strategies could provide a significant complementary contribution, since dealing with the past entails more than retribution and truth seeking. The study has wider implications in practical and theoretical considerations for ongoing armed conflicts in Africa and other parts of the world.
- Published
- 2018
194. On the validation of mixed-mode I/II crack growth theories for anisotropic rocks
- Author
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Sakha, Mahsa, Nejati, Morteza, Aminzadeh, Ali, Ghouli, Saeid, Saar, Martin O., and Driesner, Thomas
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- 2022
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195. On the applicability of connectivity metrics to rough fractures under normal stress
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Javanmard, Hoda, Saar, Martin O., and Vogler, Daniel
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- 2022
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196. Flexible CO2-plume geothermal (CPG-F): Using geologically stored CO2 to provide dispatchable power and energy storage
- Author
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Fleming, Mark R., Adams, Benjamin M., Ogland-Hand, Jonathan D., Bielicki, Jeffrey M., Kuehn, Thomas H., and Saar, Martin O.
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- 2022
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197. Connecting traces of galaxy evolution: the missing core mass -- morphological fine structure relation
- Author
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Bonfini, P., Bitsakis, T., Zezas, A., Duc, P. -A., Iodice, E., Gonzalez-Martin, O., Bruzual, G., and Sanoja, A. J. Gonzalez
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
Deep exposure imaging of early-type galaxies (ETGs) are revealing the second-order complexity of these objects, which have been long considered uniform, dispersion-supported spheroidals. "Fine structure" features (e.g. ripples, plumes, tidal tails, rings) as well as depleted stellar cores (i.e. central light deficits) characterize a number of massive ETG galaxies, and can be interpreted as the result of galaxy-galaxy interactions. We discuss how the timescale for the evolution of cores and fine structures are comparable, and hence it is expected that they develop in parallel after the major interaction event which shaped the ETG. Using archival data, we compare the "depleted stellar mass" (i.e. the mass missing from the depleted stellar core) against the prominence of the fine structure features, and observe that they correlate inversely. This result confirms our expectation that, while the Super Massive Black Hole (SMBH) binary (constituted by the SMBHs of the merger progenitors) excavates the core via three-body interactions, the gravitational potential of the newborn galaxy relaxes, and the fine structures fade below detection levels. We expect the inverse correlation to hold at least within the first Gyr from the merger which created the SMBH binary; after then, the fine structure evolves independently., Comment: Accepted for publication on MNRAS
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- 2017
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198. Ultra-Fast Reactive Transport Simulations When Chemical Reactions Meet Machine Learning: Chemical Equilibrium
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Leal, Allan M. M., Kulik, Dmitrii A., and Saar, Martin O.
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Mathematics - Optimization and Control ,Physics - Chemical Physics ,Physics - Fluid Dynamics ,Statistics - Machine Learning - Abstract
During reactive transport modeling, the computational cost associated with chemical reaction calculations is often 10-100 times higher than that of transport calculations. Most of these costs results from chemical equilibrium calculations that are performed at least once in every mesh cell and at every time step of the simulation. Calculating chemical equilibrium is an iterative process, where each iteration is in general so computationally expensive that even if every calculation converged in a single iteration, the resulting speedup would not be significant. Thus, rather than proposing a fast-converging numerical method for solving chemical equilibrium equations, we present a machine learning method that enables new equilibrium states to be quickly and accurately estimated, whenever a previous equilibrium calculation with similar input conditions has been performed. We demonstrate the use of this smart chemical equilibrium method in a reactive transport modeling example and show that, even at early simulation times, the majority of all equilibrium calculations are quickly predicted and, after some time steps, the machine-learning-accelerated chemical solver has been fully trained to rapidly perform all subsequent equilibrium calculations, resulting in speedups of almost two orders of magnitude. We remark that our new on-demand machine learning method can be applied to any case in which a massive number of sequential/parallel evaluations of a computationally expensive function $f$ needs to be done, $y=f(x)$. We remark, that, in contrast to traditional machine learning algorithms, our on-demand training approach does not require a statistics-based training phase before the actual simulation of interest commences. The introduced on-demand training scheme requires, however, the first-order derivatives $\partial f/\partial x$ for later smart predictions.
- Published
- 2017
199. A mid-infrared statistical investigation of clumpy torus model predictions
- Author
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García-González, J., Alonso-Herrero, A., Hönig, S. F., Hernán-Caballero, A., Almeida, C. Ramos, Levenson, N. A., Roche, P. F., González-Martín, O., Packham, C., and Kishimoto, M.
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
We present new calculations of the CAT3D clumpy torus models, which now include a more physical dust sublimation model as well as AGN anisotropic emission. These new models allow graphite grains to persist at temperatures higher than the silicate dust sublimation temperature. This produces stronger near-infrared emission and bluer mid-infrared (MIR) spectral slopes. We make a statistical comparison of the CAT3D model MIR predictions with a compilation of sub-arcsecond resolution ground-based MIR spectroscopy of 52 nearby Seyfert galaxies (median distance of 36 Mpc) and 10 quasars. We focus on the AGN MIR spectral index $\alpha_{MIR}$ and the strength of the 9.7 $\mu$m silicate feature $S_{Sil}$. As with other clumpy torus models, the new CAT3D models do not reproduce the Seyfert galaxies with deep silicate absorption ($S_{Sil}<-1$). Excluding those, we conclude that the new CAT3D models are in better agreement with the observed $\alpha_{MIR}$ and $S_{Sil}$ of Seyfert galaxies and quasars. We find that Seyfert 2 are reproduced with models with low photon escape probabilities, while the quasars and the Seyfert 1-1.5 require generally models with higher photon escape probabilities. Quasars and Seyfert 1-1.5 tend to show steeper radial cloud distributions and fewer clouds along an equatorial line-of-sight than Seyfert 2. Introducing AGN anisotropic emission besides the more physical dust sublimation models alleviates the problem of requiring inverted radial cloud distributions (i.e., more clouds towards the outer parts of the torus) to explain the MIR spectral indices of type 2 Seyferts., Comment: 23 pages, 17 figures, 5 tables, Accepted for publication in MNRAS
- Published
- 2017
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200. Hints on the gradual re-sizing of the torus in AGN by decomposing IRS/Spitzer spectra
- Author
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González-Martín, O., Masegosa, J., Hernán-Caballero, A., Márquez, I., Almeida, C. Ramos, Alonso-Herrero, A., Aretxaga, I., Rodríguez-Espinosa, J. M., Acosta-Pulido, J. A., Hernández-García, L., Esparza-Arredondo, D., Martínez-Paredes, M., Bonfini, P., Pasetto, A., and Dultzin, D.
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
Several authors have claimed that the less luminous active galactic nuclei (AGN) are not capable of sustaining the dusty torus structure. Thus, a gradual re-sizing of the torus is expected when the AGN luminosity decreases. Our aim is to confront mid-infrared observations of local AGN of different luminosities with this scenario. We decomposed about ~100 IRS/Spitzer spectra of LLAGN and powerful Seyferts in order to decontaminate the torus component from other contributors. We have used the affinity propagation (AP) method to cluster the data into five groups within the sample according to torus contribution to the 5-15 um range (Ctorus) and bolometric luminosity. The AP groups show a progressively higher torus contribution and an increase of the bolometric luminosity, from Group 1 (Ctorus~ 0% and logLbol ~ 41) and up to Group 5 (Ctorus ~80% and log(Lbol) ~44). We have fitted the average spectra of each of the AP groups to clumpy models. The torus is no longer present in Group 1, supporting the disappearance at low-luminosities. We were able to fit the average spectra for the torus component in Groups 3 (Ctorus~ 40% and log(Lbol)~ 42.6), 4 (Ctorus~ 60% and log(Lbol)~ 43.7), and 5 to Clumpy torus models. We did not find a good fitting to Clumpy torus models for Group 2 (Ctorus~ 18% and log(Lbol)~ 42). This might suggest a different configuration and/or composition of the clouds for Group 2, which is consistent with a different gas content seen in Groups 1, 2, and 3, according to the detections of H2 molecular lines. Groups 3, 4, and 5 show a trend to decrease of the width of the torus (which yields to a likely decrease of the geometrical covering factor), although we cannot confirm it with the present data. Finally, Groups 3, 4, and 5 show an increase on the outer radius of the torus for higher luminosities, consistent with a re-sizing of the torus according to the AGN luminosity., Comment: The main body includes 9 figures. Accepted for publication in ApJ
- Published
- 2017
- Full Text
- View/download PDF
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