Artículos de conferencia

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Algebraic Reconstruction of Source and Attenuation in SPECT Using First Scattering Measurements
(Springer, 2018) Cueva, Evelyn; Osses Alvarado, Axel Esteban; Quintana Fresno, Juan Carlos; Tejos Núñez, Cristián Andrés; Courdurier Bettancourt Matias Alejandro; Irarrazaval Mena, Pablo
Here we present an Algebraic Reconstruction Technique (ART) for solving the identification problem in Single Photon Emission Computed Tomography (SPECT). Traditional reconstruction for SPECT is done by finding the radiation source, nevertheless the attenuation of the surrounding tissue affects the data. In this context, ballistic and first scattering information are used to recover source and attenuation simultaneously. Both measurements are related with the Attenuated Radon Transform and a Klein-Nishina angular type dependency is considered for the scattering. The proposed ART algorithm allow us to obtain good reconstructions of both objects in a few number of iterations.
ANTICHOLINERGIC THERAPY IN CYSTIC-FIBROSIS PATIENTS
(EDITIONS SCIENTIFIQUES ELSEVIER, 1995) Sánchez Díaz, Ignacio
Arsenic-related cancer mortality in Northern Chile, 1989-98
(LIPPINCOTT WILLIAMS & WILKINS, 2004) Bates, M; Marshall, G; Ferreccio, C; Smith, A
Basic aspects of oviduct function
(PARTHENON PUBLISHING GROUP LTD, 1997) Croxatto, HB; Ortiz, ME; Villalon, M; Cardenas, H; Imarai, M; Hermoso, M; Velasquez, L; Orihuela, P; Coutifaris, C; Mastroianni, L
Bayesian Modeling of Censored Partial Linear Models using Scale-Mixtures of Normal Distributions
(AMER INST PHYSICS, 2012) Castro, Luis M.; Lachos, Victor H.; Ferreira, Guillermo P.; Arellano Valle, Reinaldo B.; Stern, JM; Lauretto, MD; Polpo, A; Diniz, MA
Regression models where the dependent variable is censored (limited) are usually considered in statistical analysis. Particularly, the case of a truncation to the left of zero and a normality assumption for the error terms is studied in detail by [1] in the well known Tobit model. In the present article, this typical censored regression model is extended by considering a partial linear model with errors belonging to the class of scale mixture of normal distributions. We achieve a fully Bayesian inference by adopting a Metropolis algorithm within a Gibbs sampler. The likelihood function is utilized to compute not only some Bayesian model selection measures but also to develop Bayesian case-deletion influence diagnostics based on the q-divergence measures. We evaluate the performances of the proposed methods with simulated data. In addition, we present an application in order to know what type of variables affect the income of housewives.
Cyclooxygenase-2/PGE(2) system mediates the effect of platelet activating factor in oviductal ciliated cells.
(SOC STUDY REPRODUCTION, 1998) Villalon, M; Morales, B; Barrera, N; Oliva, C
Effect of prostaglandins F-2 alpha and E-2 on human sperm motility
(CAMBRIDGE UNIV PRESS, 2000) Kerr, B; Villalon, MJ
Effect of sex hormones in the swelling control of human cervical mucus
(CAMBRIDGE UNIV PRESS, 2000) Espinosa, M; Villalon, MJ
EMBRYO SECRETED FACTORS INCREASE THE FREQUENCY OF CILIARY BEAT OF HAMSTER OVIDUCTAL CILIATED CELLS
(SOC STUDY REPRODUCTION, 1995) HERMOSO, MA; VILLALON, MJ
Examining the effect of freezing on starch gelatinization during heating at high rates using online in situ hot-stage video-microscopy and differential scanning calorimetry
(INST CHEMICAL ENGINEERS, 2016) Molina Maydl, María Teresa; Leiva Maturana, Ana María; Bouchon Aguirre, Pedro Alejandro
HEALTH-RELATED QUALITY OF LIFE OF EATING DISORDERS IN CHILEAN ADOLESCENTS
(ELSEVIER SCIENCE INC, 2019) Inostroza, Carolina; Urrejola, Pascuala; Zubarew, Tamara; Loreto Correa, Maria; Gil, Aurora A.; Bedregal, Paula; Vogel, Melina
Hepatic fatty acid profile in mice with nonalcoholic fatty liver disease using magnetic resonance spectroscopy
(2019) Xavier, Aline Carvalho da Silva; Zacconi, Flavia C. M.; Cabrera García, Daniel Alejandro; Fuenzalida, Karen; Andía Kohnenkampf, Marcelo Edgardo
Nonalcoholic fatty liver disease (NAFLD) is characterized by the accumulation of intracellular fatty acids in the liver. The only method to confirm the stage of this disease is the biopsy, but it is invasive and risky to patients. The idea of defining a classifier using magnetic resonance spectroscopy (MRS) emerges due to the need to find a way to replace biopsy with a non-invasive method that can classify NAFLD based on the chemical structure of fatty acids stored in the liver. The purpose of this study is to investigate and compare the composition of fatty acids to the metabolites signals in MRS in NAFLD mice liver at 2 time-point during the progression of the disease. A group of C57BL/6 mice was fed with high-fat diet for one month (N = 8) and for three months (N = 6). First, we made a histological analysis to the liver. Then, we analysed the fatty acids with gas chromatography (GC) and MRS. As a result, the histological analysis showed the progression of fat content, and the GC analysis detected a different fatty acid liver composition during the progression of NAFLD along with an increase of the total fat storage in the liver. The differences in the composition fatty acids are also reflected in the MR Spectrum, which could have clinical potential for monitoring the progression of this disease with a non-invasive technique.
HIV infection of astrocytes increases release of Dickkopf-1 protein by a gap junction and hemichannel dependent mechanism
(Springer, 2012) Orellana Roca, Juan Andrés; Sáez, Juan Carlos; Berman, Joan; Eugenín Arce, Eliseo Alberto
Human immunodeficiency virus-1 (HIV) is a major public health issue, with a significant CNS complication of infection, NeuroAIDS. In vivo, microglia/macrophages are the main cells infected. However, a low but significant number of HIV infected astrocytes also has been detected, but their role in the pathogenesis of NeuroAIDS is not well understood. Our previous data indicated that HIV infection of astrocytes increased expression of the glycoprotein, dickkopf-1 protein (Dkk1), a soluble inhibitor of the wnt pathway. In HIV infected cultures of human astrocytes, secretion of Dkk1 was highly regulated by functional gap junction channels and connexin43 hemichannels. We also demonstrated that Dkk1 expression in astrocytes was increased in human brain tissue sections of individuals with HIV encephalitis as compared to tissue sections from uninfected individuals. We demonstrated that in primary cells, Dkk1 secretion did not participate in bystander killing of uninfected astrocytes or viral reactivation. However, its secretion regulates neuronal damage measured by collapse of neuronal processes. Thus, we demonstrated that HIV infection of astrocytes dysregulates secretion of Dkk1 by a mechanisms that involves both gap junctions as well as hemichannels that contributes to the neuropathogenesis observed in HIV infected individuals.
Impact of Awake Prone Positioning on Inspiratory Effort and Work of Breathing. A Physiological Study in Healthy Subjects
(American Thoracic Society, 2022) Damiani Rebolledo, L. Felipe; Basoalto Escobar, Roque Ignacio; Bachmann Barrón, María Consuelo; Jalil Contreras, Yorschua Frederick; Acuña, V.; Díaz, G.; Mella, J.; García Valdés, Patricio Hernán; Moya Gallardo, Eduardo Sebastián; Villarroel, G.; Retamal Montes, Jaime; Bugedo Tarraza, Guillermo; Bruhn, Alejandro
INTRACELLULAR CALCIUM-CONCENTRATION INCREASES IN MONKEY OVIDUCTAL CILIATED CELLS AFTER STIMULATION WITH EXTRACELLULAR ATP
(SOC STUDY REPRODUCTION, 1995) VILLALON, MJ; DANOVARO, MC; HINDS, TR
Is Gamma (P.1) Variant Associated with a Higher Severity in ICU Patients with SARS-CoV-2 Infection
(2022) Vera, M.; Angulo, J.; Medina, R.; Ferres, M.; Bruhn, A.; Castro, R.; Pardo-Roa, C.
The Omicron variant of SARS-CoV-2 has been shown to evade neutralizing antibodies elicited by vaccination or infection. Despite the global spread of the Omicron variant, even among highly vaccinated populations, death rates have not increased concomitantly. These data suggest that immune mechanisms beyond antibody-mediated virus neutralization may protect against severe disease. In addition to neutralizing pathogens, antibodies contribute to control and clearance of infections through Fc effector mechanisms. Here, we probed the ability of vaccine-induced antibodies to drive Fc effector activity against the Omicron variant using samples from individuals receiving one of three SARS-CoV-2 vaccines. Despite a substantial loss of IgM, IgA, and IgG binding to the Omicron variant receptor binding domain (RBD) in samples from individuals receiving BNT162b2, mRNA-1273, and CoronaVac vaccines, stable binding was maintained against the full-length Omicron Spike protein. Compromised RBD binding IgG was accompanied by a loss of RBD-specific antibody Fc gamma receptor (Fe gamma R) binding in samples from individuals who received the CoronaVac vaccine, but RBD-specific Fc gamma R2a and Fc gamma R3a binding was preserved in recipients of mRNA vaccines. Conversely, Spike protein-specific antibodies exhibited persistent but reduced binding to Fc gamma Rs across all three vaccines, although higher binding was observed in samples from recipients of mRNA vaccines. This was associated with preservation of Fc gamma R2a and Fc gamma R3a binding antibodies and maintenance of Spike protein-specific antibody-dependent natural killer cell activation. Thus, despite the loss of Omicron neutralization, vaccine-induced Spike protein-specific antibodies continue to drive Fc effector functions, suggesting a capacity for extraneutralizing antibodies to contribute to disease control.
On the Accuracy of Eikonal Approximations in Cardiac Electrophysiology in the Presence of Fibrosis
(Springer, 2023) Gander, Lia; Krause, Rolf; Weiser, Martin; Sahli Costabal, Francisco; Pezzuto, Simone
Fibrotic tissue is one of the main risk factors for cardiac arrhythmias. It is therefore a key component in computational studies. In this work, we compare the monodomain equation to two eikonal models for cardiac electrophysiology in the presence of fibrosis. We show that discontinuities in the conductivity field, due to the presence of fibrosis, introduce a delay in the activation times. The monodomain equation and eikonal-diffusion model correctly capture these delays, contrarily to the classical eikonal equation. Importantly, a coarse space discretization of the monodomain equation amplifies these delays, even after accounting for numerical error in conduction velocity. The numerical discretization may also introduce artificial conduction blocks and hence increase propagation complexity. Therefore, some care is required when comparing eikonal models to the discretized monodomain equation.
PIVOT: Prompting for Video Continual Learning
(IEEE Computer Soc., 2023) Villa Ojeda, Andres Felipe; Alcazar, Juan Leon; Alfarra, Motasem; Alhamoud, Kumail; Hurtado, Julio; Heilbron, Fabian Caba; Soto, Alvaro; Ghanem, Bernard
Modern machine learning pipelines are limited due to data availability, storage quotas, privacy regulations, and expensive annotation processes. These constraints make it difficult or impossible to train and update large-scale models on such dynamic annotated sets. Continual learning directly approaches this problem, with the ultimate goal of devising methods where a deep neural network effectively learns relevant patterns for new (unseen) classes, without significantly altering its performance on previously learned ones. In this paper, we address the problem of continual learning for video data. We introduce PIVOT, a novel method that leverages extensive knowledge in pre-trained models from the image domain, thereby reducing the number of trainable parameters and the associated forgetting. Unlike previous methods, ours is the first approach that effectively uses prompting mechanisms for continual learning without any in-domain pre-training. Our experiments show that PIVOT improves state-of-the-art methods by a significant 27% on the 20-task ActivityNet setup.
Polygastric flexor muscle of the index finger and its clinical implications
(2023) Riveros, Andrés; Inzunza, Óscar; Burdiles, Álvaro; Farfán, Emilio
Although muscle variations in the forearm have been widely reported, the presence of supernumerary muscles in this compartment may be associated with compressive disorders of the nerves of the upper limb. The purpose of this study was to report the finding of a polygastric flexor muscle of the index finger (PFID), a supernumerary muscle associated with the anterior compartment of the forearm, the morphology and pathway of which are closely related to the median nerve. The PFID was found in a routine dissection of an upper right limb. Following a dissection methodology by planes, a narrow, polygastric muscle was identified, formed sequentially and interspersed by four tendons and three muscle bellies, that extended between the common flexor muscle mass of the anterior compartment of the forearm and the index finger. The sixth part of the PFID was partially in the carpal tunnel and established close relation with the median nerve, which was displaced superficially. Knowledge of this and other muscle variations that appear in the forearm and carpal tunnel are relevant when performing a differential diagnosis of carpal tunnel syndrome or in planning surgery on this canal.
Preimplantational hamster embryos produce prostaglandin E(2) and platelet activating factor in vitro
(SOC STUDY REPRODUCTION, 1996) Hermoso, M; Magness, RR; Bavister, B; Villalon, M

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