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1,185 results on '"Hernández, Diego"'

1. Multi-machine preventative maintenance scheduling with imperfect interventions: a restless bandit approach

Author

Ruiz-Hernandez, Diego, Pinar-Pérez, Jesús María, and Delgado-Gómez, David

Subjects
Computer Science - Discrete Mathematics, Mathematics - Numerical Analysis
Abstract

In this paper we address the problem of allocating the efforts of a collection of repairmen to a number of deteriorating machines in order to reduce operation costs and to mitigate the cost (and likelihood) of unexpected failures. Notwithstanding these preventive maintenance interventions are aimed at returning the machine to a so-called as-good-as-new state, unforeseeable factors may imply that maintenance interventions are not perfect and the machine is only returned to an earlier (uncertain) state of wear. The problem is modelled as a restless bandit problem and an index policy for the sequential allocation of maintenance tasks is proposed. A series of numerical experiments shows the strong performance of the proposed policy. Moreover, the methodology is of interest in the general context of dynamic resource allocation and restless bandit problems, as well as being useful in the particular imperfect maintenance model described., Comment: Published in Computers and Operations Research (ELSEVIER), July 2020. DOI: https://doi.org/10.1016/j.cor.2020.104927 Article available under the terms of the CC-BY-NC-ND licence

Published
2024
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4. Effect of metformin and metformin/linagliptin on gut microbiota in patients with prediabetes

Author

Estrella, Martínez-López Yoscelina, Daniel, Neri-Rosario, Armando, Esquivel-Hernández Diego, Cristian, Padron-Manrique, Aarón, Vázquez-Jiménez, Paul, Sánchez-Castañeda Jean, David, Girón-Villalobos, Cristian, Mendoza-Ortíz, de Lourdes, Reyes-Escogido María, Lola, Evia-Viscarra Maria, Alberto, Aguilar-Garcia, Osbaldo, Resendis-Antonio, and Rodolfo, Guardado-Mendoza

Published
2024
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5. Effect of metformin and metformin/linagliptin on gut microbiota in patients with prediabetes

Author

Martínez-López Yoscelina Estrella, Neri-Rosario Daniel, Esquivel-Hernández Diego Armando, Padron-Manrique Cristian, Vázquez-Jiménez Aarón, Sánchez-Castañeda Jean Paul, Girón-Villalobos David, Mendoza-Ortíz Cristian, Reyes-Escogido María de Lourdes, Evia-Viscarra Maria Lola, Aguilar-Garcia Alberto, Resendis-Antonio Osbaldo, and Guardado-Mendoza Rodolfo

Subjects
Gut microbiota, Metformin, Linagliptin/metformin, Insulin resistance, Pancreatic β-cell function, Medicine, Science
Abstract

Abstract Lifestyle modifications, metformin, and linagliptin reduce the incidence of type 2 diabetes (T2D) in people with prediabetes. The gut microbiota (GM) may enhance such interventions' efficacy. We determined the effect of linagliptin/metformin (LM) vs metformin (M) on GM composition and its relationship to insulin sensitivity (IS) and pancreatic β-cell function (Pβf) in patients with prediabetes. A cross-sectional study was conducted at different times: basal, six, and twelve months in 167 Mexican adults with prediabetes. These treatments increased the abundance of GM SCFA-producing bacteria M (Fusicatenibacter and Blautia) and LM (Roseburia, Bifidobacterium, and [Eubacterium] hallii group). We performed a mediation analysis with structural equation models (SEM). In conclusion, M and LM therapies improve insulin sensitivity and Pβf in prediabetics. GM is partially associated with these improvements since the SEM models suggest a weak association between specific bacterial genera and improvements in IS and Pβf.

Published
2024
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12. A Real Use Case of Semi-Supervised Learning for Mammogram Classification in a Local Clinic of Costa Rica

Author

Calderon-Ramirez, Saul, Murillo-Hernandez, Diego, Rojas-Salazar, Kevin, Elizondo, David, Yang, Shengxiang, and Molina-Cabello, Miguel

Subjects
Electrical Engineering and Systems Science - Image and Video Processing, Computer Science - Computer Vision and Pattern Recognition
Abstract

The implementation of deep learning based computer aided diagnosis systems for the classification of mammogram images can help in improving the accuracy, reliability, and cost of diagnosing patients. However, training a deep learning model requires a considerable amount of labeled images, which can be expensive to obtain as time and effort from clinical practitioners is required. A number of publicly available datasets have been built with data from different hospitals and clinics. However, using models trained on these datasets for later work on images sampled from a different hospital or clinic might result in lower performance. This is due to the distribution mismatch of the datasets, which include different patient populations and image acquisition protocols. The scarcity of labeled data can also bring a challenge towards the application of transfer learning with models trained using these source datasets. In this work, a real world scenario is evaluated where a novel target dataset sampled from a private Costa Rican clinic is used, with few labels and heavily imbalanced data. The use of two popular and publicly available datasets (INbreast and CBIS-DDSM) as source data, to train and test the models on the novel target dataset, is evaluated. The use of the semi-supervised deep learning approach known as MixMatch, to leverage the usage of unlabeled data from the target dataset, is proposed and evaluated. In the tests, the performance of models is extensively measured, using different metrics to assess the performance of a classifier under heavy data imbalance conditions. It is shown that the use of semi-supervised deep learning combined with fine-tuning can provide a meaningful advantage when using scarce labeled observations. We make available the novel dataset for the benefit of the community.

Published
2021

16. The socioeconomic impact of cancer on patients and their relatives: Organisation of European Cancer Institutes task force consensus recommendations on conceptual framework, taxonomy, and research directions

Author

Schlander, Michael, van Harten, Wim, Retèl, Valesca P, Pham, Phu Duy, Vancoppenolle, Julie M, Ubels, Jasper, López, Olaya Seoane, Quirland, Camila, Maza, Felipe, Aas, Eline, Crusius, Bernd, Escobedo, Agustín, Franzen, Nora, Fuentes-Cid, Jeanette, Hernandez, Diego, Hernandez-Villafuerte, Karla, Kirac, Iva, Paty, Artus, Philip, Thierry, Smeland, Sigbjørn, Sullivan, Richard, Vanni, Elena, Varga, Sinisa, Vermeulin, Thomas, and Eckford, Rachel D

Published
2024
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18. Diagnosis and Degree of Evolution in a Keratoconus-Type Corneal Ectasia from Image Processing

Author

Otuna-Hernández, Diego, Espinoza-Castro, Leslie, Yánez-Contreras, Paula, Villalba-Meneses, Fernando, Cadena-Morejón, Carolina, Guevara, César, Cruz-Varela, Jonathan, Tirado-Espín, Andrés, Almeida-Galárraga, Diego, Filipe, Joaquim, Editorial Board Member, Ghosh, Ashish, Editorial Board Member, Prates, Raquel Oliveira, Editorial Board Member, Zhou, Lizhu, Editorial Board Member, Narváez, Fabián R., editor, Urgilés, Fernando, editor, Bastos-Filho, Teodiano Freire, editor, and Salgado-Guerrero, Juan Pablo, editor

Published
2023
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24. Editor's Choice – Management of Lower Extremity Venous Outflow Obstruction: Results of an International Delphi Consensus

Author

Abramowitz, Steve, Al-Hakim, Ramsey, Almeida, Jose, Avgerinos, Efthymios, Bashir, Riyaz, Binkert, Cristoph, Bismuth, Jean, Bjarnason, Haroldur, Black, Stephen, Chaer, Rabih, Comerota, Tony, Davies, Alun, de Graaf, Rick, DeRubertis, Brian, Desai, Kush, Dexter, David, Dillavou, Ellen, Dumantepe, Mert, Elias, Steve, Fastabend, Carl, Gagne, Paul, Garcia, Mark, Gasparis, Tony, George, Jon, Gibson, Kathy, Gillespie, David, Gohel, Manjit, Guimaraes, Marcelo, Henke, Peter, Hernandez, Diego, Hofmann, Lawrence, Hsu, Wan-hsien, Jalaie, Houman, Jolly, Michael, Kabnick, Lowell, Karunanithy, Narayan, Kaufmann, John, Khaja, Minhaj, Kokkosis, Angela, Kolli, Kanti, Kolluri, Raghu, Kuo, Will, Labropoulos, Nicos, Lessne, Mark, Leung, Daniel, Lichtenberg, Michael, Lim, Chung, Lohr, Joann, Lurie, Fedor, Machan, Lindsay, Malhotra, Rahul, Marston, William, McLafferty, Robert, Meissner, Mark, Mendes, Bobby, Muck, Pat, Murphy, Erin, O'Sullivan, Gerry, Ozsvath, Kathleen, Pappas, Peter, Patel, Parag, Pena, Consantino, Ramirez-Ortega, Marta, Razavi, Mahmood, Rooke, Thom, Ross, Charles, Rundback, John, Sadek, Michael, Saha, Prakash, Saleem, Taimur, Silver, Mitchell, Sista, Akhi, Spencer, Brooke, Sterling, Keith, Streif, Michael, Sudheendra, Deepak, Thorpe, Patti, Ting, Windsor, Tosenovsky, Patrik, Tripathi, Ramesh, van Laanen, Jorinde, Varcoe, Ramon, Villalba, Laurentia, Wang, Jeff, Weinberg, Mitchell, Wigham, Andrew, Wilton, Emma, Winokur, Ron, Yako, Hiroyoshi, Black, Stephen A., Fleck, Bruce, and Hofmann, Lawrence V.

Published
2024
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26. Partition Quantitative Assessment (PQA): A quantitative methodology to assess the embedded noise in clustered omics and systems biology data

Author

Camacho-Hernández, Diego A., Nieto-Caballero, Victor E., León-Burguete, José E., and Freyre-González, Julio A.

Subjects
Quantitative Biology - Genomics
Abstract

Identifying groups that share common features among datasets through clustering analysis is a typical problem in many fields of science, particularly in post-omics and systems biology research. In respect of this, quantifying how a measure can cluster or organize intrinsic groups is important since currently there is no statistical evaluation of how ordered is, or how much noise is embedded in the resulting clustered vector. Many of the literature focuses on how well the clustering algorithm orders the data, with several measures regarding external and internal statistical measures; but none measure has been developed to statistically quantify the noise in an arranged vector posterior a clustering algorithm, i.e., how much of the clustering is due to randomness. Here, we present a quantitative methodology, based on autocorrelation, to assess this problem., Comment: 9 pages, 6 figures

Published
2021

27. Rapid Lipid Content Screening in Neochloris oleoabundans Utilizing Carbon-Based Dielectrophoresis.

Author

Galicia-Medina, Cynthia M, Vázquez-Piñón, Matías, Alemán-Nava, Gibran S, Gallo-Villanueva, Roberto C, Martínez-Chapa, Sergio O, Madou, Marc J, Camacho-León, Sergio, García-Pérez, Jonathan S, Esquivel-Hernández, Diego A, Parra-Saldívar, Roberto, and Pérez-González, Víctor H

Subjects
biofuel, carbon-microelectromechanical systems, dielectrophoresis, microalgae, microfluidics, Clinical Research, Nanotechnology
Abstract

In this study, we carried out a heterogeneous cytoplasmic lipid content screening of Neochloris oleoabundans microalgae by dielectrophoresis (DEP), using castellated glassy carbon microelectrodes in a PDMS microchannel. For this purpose, microalgae were cultured in nitrogen-replete (N+) and nitrogen-deplete (N-) suspensions to promote low and high cytoplasmic lipid production in cells, respectively. Experiments were carried out over a wide frequency window (100 kHz-30 MHz) at a fixed amplitude of 7 VPP. The results showed a statistically significant difference between the dielectrophoretic behavior of N+ and N- cells at low frequencies (100-800 kHz), whereas a weak response was observed for mid- and high frequencies (1-30 MHz). Additionally, a finite element analysis using a 3D model was conducted to determine the dielectrophoretic trapping zones across the electrode gaps. These results suggest that low-cost glassy carbon is a reliable material for microalgae classification-between low and high cytoplasmic lipid content-through DEP, providing a fast and straightforward mechanism.

Published
2021

30. Combining GHOST and Casper

Author

Buterin, Vitalik, Hernandez, Diego, Kamphefner, Thor, Pham, Khiem, Qiao, Zhi, Ryan, Danny, Sin, Juhyeok, Wang, Ying, and Zhang, Yan X

Subjects
Computer Science - Cryptography and Security, 68W15
Abstract

We present "Gasper," a proof-of-stake-based consensus protocol, which is an idealized version of the proposed Ethereum 2.0 beacon chain. The protocol combines Casper FFG, a finality tool, with LMD GHOST, a fork-choice rule. We prove safety, plausible liveness, and probabilistic liveness under different sets of assumptions.

Published
2020

31. Proceedings of the VIII International Workshop on Locational Analysis and Related Problems

Author

Baldomero-Naranjo, Marta, Espejo-Miranda, Inmaculada, Martínez-Merino, Luisa I., Rodríguez-Chía, Antonio M., and Ruiz-Hernández, Diego

Subjects
Computer Science - Other Computer Science
Abstract

The International Workshop on Locational Analysis and Related Problems will take place during September 27-29, 2017 in Segovia (Spain). It is organized by the Spanish Location Network and Location Group GELOCA (SEIO). GELOCA is a working group on location belonging to the Statistics and Operations Research Spanish Society. The Spanish Location Network is a group of more than 100 researchers distributed into 16 nodes corresponding to several Spanish universities. The Network has been funded by the Spanish Government. Every year, the Network organizes a meeting to promote the communication between its members and between them and other researchers, and to contribute to the development of the location field and related problems. Previous meetings took place in M\'alaga (September 14-16, 2016), Barcelona (November 25-28, 2015), Sevilla (October 1-3, 2014), Torremolinos (M\'alaga, June 19-21, 2013), Granada (May 10-12, 2012), Las Palmas de Gran Canaria (February 2-5, 2011) and Sevilla (February 1-3, 2010). The topics of interest are location analysis and related problems. It includes location, networks, transportation, routing, logistics models, as well as, exact and heuristic solution methods, and computational geometry, among others.

Published
2020

46. The Difficulties of Financial Inclusion via Large Banks: Evidence from Mexico

Author

Castellanos, Sara G, Jiménez-Hernández, Diego, Mahajan, Aprajit, and Seira, Enrique

Subjects
Mexico
Abstract

We provide evidence on why large financial institutions in developing economies have had difficulties expanding formal sector credit. Using detailed credit data and a product that accounted for 15% of all first-time formal loans, we show that borrowers new to formal credit default at high rates and generate ex-ante unpredictable revenue. Using a large country-wide experiment, we show that expost contract terms do little to mitigate risk, implying moral hazard is not a primary cause of default. Failing to make its flagship financial inclusion product profitable, the bank eventually discontinued it

Published
2019

47. Tree diversity and species composition of tropical dry forests in Vietnam's Central Highlands Region

Author

Thanh Tuan Nguyen, Quang Bao Tran, Rodríguez-Hernández Diego I., and Gliottone Ilaria

Subjects
tropical dry forests of vietnam, species composition, tree diversity, tree regeneration, forest type, Forestry, SD1-669.5
Abstract

Tree species inventories, particularly of poorly known dry forests, are necessary to protect and restore them in degraded landscapes. The present research has been conducted to compare taxonomic diversity and community composition in four dry forests (DF) categories with different standing volume levels: very low (DFV), low (DFP), medium (DFM) and high (DFR). This quantitative assessment of taxonomic diversity, forest structure and species composition were obtained from 103 sample plots (0.1 ha each). The regeneration potential of trees was assessed in 515 subplots (4 m × 4 m) located within the 103 plots. A total of 1,072 trees representing 87 species belonging to 37 families were recorded in 10.3 ha of total sampled area. The ranges of diversity indices observed in the four forest types were: Margalef's (5.44–8.43), Shannon-Wiener (1.80–2.29), Simpson diversity (0.76–0.87) and evenness (0.32–0.35). The regeneration potential of rare and threatened species Dalbergia oliveri, Hopea recopei, Dalbergia bariensis, Sindora siamensis, Parashorea stellata was observed to be poor. Conversely, Cratoxylon formosum, Shorea obtusa, Dipterocarpus tuberculatus, Dipterocarpus obtusifolius, Terminalia alata, Shorea siamensis and Xylia xylocarpa were the most dominant species at the seedling and sapling stage, showing a strong potential for regeneration. Overall, this study provides useful information on tree species diversity and composition for tropical dry forests which can be used as baseline data to develop incoming plans for forest management and conservation in Vietnam's Central Highlands Region.

Published
2022
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