4,716 results on '"Ulloa, P."'
Search Results
2. Artificial Intelligence Use to Empower the Implementation of OER and the UNESCO OER Recommendation
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Ebba Ossiannilsson, Rosa Leonor Ulloa Cazarez, Claire Goode, Chadia Mansour, and Cristine Martins Gomes De Gusmão
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Artificial intelligence (AI) has recently been gaining ground, particularly since November 2022, with the introduction of generative tools based on natural language processing and neural network algorithms. These kinds of tools have great potential for creators and users of Open Educational Resources (OER) and the Open Movement itself but they also represent risks. The International Council for Open and Distance Education OER Advocacy Committee (OERAC) developed two workshops to present the role of AI in OER at two international conferences in the fall of 2023. The workshops presented the features, benefits, key challenges, and practical issues related to using AI technologies from professional, ethical, sustainable, and equitable perspectives, while also focusing on the five areas of the UNESCO OER Recommendation. Participants were dynamically engaged in discussions, and documented their ideas in formats that could be used as OER in themselves. The OERAC noted and categorized the results, and developed short summaries and drafts for further work. Finally, drawing on the findings from the workshops, we asked ChatPDF for a second opinion on further suggestions for AI in connection with OER, which in turn related to the five areas of the recommendation. We conclude that, while there is great potential for the use of AI in the context of the Open Movement, there is also a need for professional ethics, equity, and sustainable capacity building, access, inclusion, policy, models, and international collaboration.
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- 2024
3. Probing nonlocal correlations in magnetic rare-earth clusters
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Facemyer, David W. and Ulloa, Sergio E.
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Condensed Matter - Other Condensed Matter ,Quantum Physics - Abstract
Understanding and quantifying entanglement entropy is crucial to characterize the quantum behaviors that drive phenomena in a variety of systems. Rare-earth spin complexes, with their unique magnetic properties, provide fertile ground for exploring these nonlocal correlations. In this work, we study Eu$^{2+}$ ions deposited on a Au(111) substrate, modeling finite clusters of large spin-moments using a Heisenberg Hamiltonian parameterized by first-principles calculations. Our analysis reveals a one-to-one correspondence between structures in the differential conductance profiles and changes in the von Neumann entanglement entropy of bipartite subsystems, influenced by probe-ion separation and applied magnetic fields. Distinct braiding patterns in the conductance profiles are shown to correspond to stepwise changes in the entanglement entropy, providing a new avenue for investigating quantum correlations. These results establish a foundation for experimentally probing and controlling entanglement in lanthanide-based systems, with potential applications in quantum technologies., Comment: 8 pages, 7 figures
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- 2024
4. Beyond time delays: How web scraping distorts measures of online news consumption
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Ulloa, Roberto, Mangold, Frank, Schmidt, Felix, Gilsbach, Judith, and Stier, Sebastian
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Computer Science - Computers and Society - Abstract
As the exploration of digital behavioral data revolutionizes communication research, understanding the nuances of data collection methodologies becomes increasingly pertinent. This study focuses on one prominent data collection approach, web scraping, and more specifically, its application in the growing field of research relying on web browsing data. We investigate discrepancies between content obtained directly during user interaction with a website (in-situ) and content scraped using the URLs of participants' logged visits (ex-situ) with various time delays (0, 30, 60, and 90 days). We find substantial disparities between the methodologies, uncovering that errors are not uniformly distributed across news categories regardless of classification method (domain, URL, or content analysis). These biases compromise the precision of measurements used in existing literature. The ex-situ collection environment is the primary source of the discrepancies (~33.8%), while the time delays in the scraping process play a smaller role (adding ~6.5 percentage points in 90 days). Our research emphasizes the need for data collection methods that capture web content directly in the user's environment. However, acknowledging its complexities, we further explore strategies to mitigate biases in web-scraped browsing histories, offering recommendations for researchers who rely on this method and laying the groundwork for developing error-correction frameworks.
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- 2024
5. A Capacitated Collection-and-Delivery-Point Location Problem with Random Utility Maximizing Customers
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Ulloa, David Pinzon, Metnan, Ammar, and Frejinger, Emma
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Mathematics - Optimization and Control - Abstract
We consider a strategic decision-making problem where a logistics provider (LP) seeks to locate collection and delivery points (CDPs) with the objective to reduce total logistics costs. The customers maximize utility that depends on their perception of home delivery service as well as the characteristics of the CDPs, including their location. At the strategic planning level, the LP does not have complete information about customers' preferences and their exact location. We introduce a mixed integer non-linear formulation of the problem and propose two linear reformulations. The latter involve sample average approximations and closest assignment constraints, and in one of the formulations we use scenario aggregation to reduce its size. We solve the formulations with a general-purpose solver using a standard Benders decomposition method. Based on extensive computational results and a realistic case study, we find that the problem can be solved efficiently. However, the level of uncertainty in the instances determines which approach is the most efficient. We use an entropy measure to capture the level of uncertainty that can be computed prior to solving. Furthermore, the results highlight the value of accurate demand modeling, as customer preferences have an important impact on the solutions and associated costs.
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- 2024
6. When LAMOST meets Gaia DR3 Exploring the metallicity of open clusters
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Zhang, R., Wang, Guo-Jian, Yuxi, Lu, Guo, Sufen, Lucatello, S., Fu, Xiaoting, Wang, Haifeng, Wang, Luqian, Schiappacasse-Ulloa, J., Chen, Jianxing, and Han, Zhanwen
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Astrophysics - Astrophysics of Galaxies ,Astrophysics - Solar and Stellar Astrophysics - Abstract
Context. Open clusters (OCs) are valuable probes of stellar population characteristics. Their age and metallicity provide insights into the chemical enrichment history of the Milky Way. By studying the metallicity of OCs, we can explore the spatial distribution of composition across the Galaxy and understand stellar birth radii through chemical tagging. However, inferring the original positions of OCs remains a challenge. Aims. This study investigates the distribution of metallicity in the solar neighborhood using data from Gaia DR3 and LAMOST spectra. By measuring accurate ages and metallicities, we aim to derive birth radii and understand stellar migration patterns. Methods. We selected 1131 OCs within 3 kpc of the Sun from Gaia DR3 and LAMOST DR8 low-resolution spectra (R=1800). To correct the LAMOST data, we incorporated high-resolution spectra from GALAH DR3 (R=28000) using an artificial neural network. The average metallicity of the OCs was derived from reliable [Fe/H] values of their members. We examined the metallicity distribution across the Galaxy and calculated birth radii based on age and metallicity. Results. The correction method reduces the systematic offset in LAMOST data. We found a metallicity gradient as a function of Galactocentric distance and guiding radii. Comparisons with chemo-dynamic simulations show that observed metallicity values are slightly lower than predicted when uncertainties are ignored, but the metallicity gradients align with previous studies. We also inferred that many OCs near the Sun likely originated from the outer Galactic disk.
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- 2024
7. Magnetic susceptibility and entanglement of three interacting qubits under magnetic field and anisotropy
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Castorene, Bastian, Peña, Francisco J., Norambuena, Ariel, Ulloa, Sergio E., Araya, Cristobal, and Vargas, Patricio
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Condensed Matter - Statistical Mechanics - Abstract
This work investigates a system of three entangled qubits within the XXX model, subjected to an external magnetic field in the $z$-direction and incorporating an anisotropy term along the $y$-axis. We explore the thermodynamics of the system by calculating its magnetic susceptibility and analyzing how this quantity encodes information about entanglement. By deriving rigorous bounds for susceptibility, we demonstrate that their violation serves as an entanglement witness. Our results show that anisotropy enhances entanglement, extending the temperature range over which it persists. Additionally, by tracing over the degrees of freedom of two qubits, we examine the reduced density matrix of the remaining qubits and find that its entropy under the influence of the magnetic field can be mapped to an effective thermal bath at $(B,K) > 0$ K., Comment: 6 Figures
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- 2024
8. Homogenized Models of Mechanical Metamaterials
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Ulloa, J., Ariza, M. P., Andrade, J. E., and Ortiz, M.
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Condensed Matter - Materials Science ,Physics - Applied Physics - Abstract
Direct numerical simulations of mechanical metamaterials are prohibitively expensive due to the separation of scales between the lattice and the macrostructural size. Hence, multiscale continuum analysis plays a pivotal role in the computational modeling of metastructures at macroscopic scales. In the present work, we assess the continuum limit of mechanical metamaterials via homogenized models derived rigorously from variational methods. It is shown through multiple examples that micropolar-type effective energies, derived naturally from analysis, properly capture the kinematics of discrete lattices in two and three dimensions. Moreover, the convergence of the discrete energy to the continuum limit is shown numerically. We provide open-source computational implementations for all examples, including both discrete and homogenized models., Comment: Accepted version
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- 2024
9. Assessing the Readability of English and Spanish Online Patient Educational Materials for Deep Venous Thrombosis
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Wang, Karissa M, Ramirez, Joel L, Iannuzzi, James C, and Ulloa, Jesus G
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Biomedical and Clinical Sciences ,Clinical Sciences ,Clinical Research ,Deep venous thrombosis ,DVT ,Educational materials ,Online patient education ,Readability ,Surgery ,Clinical sciences - Abstract
IntroductionOnline patient educational materials (OPEMs) help patients engage in their health care. The American Medical Association (AMA) recommends OPEM be written at or below the 6th grade reading level. This study assessed the readability of deep venous thrombosis OPEM in English and Spanish.MethodsGoogle searches were conducted in English and Spanish using "deep venous thrombosis" and "trombosis venosa profunda," respectively. The top 25 patient-facing results were recorded for each, and categorized into source type (hospital, professional society, other). Readability of English OPEM was measured using several scales including the Flesch Reading Ease Readability Formula and Flesch-Kincaid Grade Level. Readability of Spanish OPEM was measured using the Fernández-Huerta Index and INFLESZ Scale. Readability was compared to the AMA recommendation, between languages, and across source types.ResultsOnly one (4%) Spanish OPEM was written at an easy level, compared to 7 (28%) English OPEM (P = 0.04). More English (28%) OPEM were easy to read compared to Spanish (4%), with a significant difference in reading difficulty breakdown between languages (P = 0.04). The average readability scores for English and Spanish OPEM across all scales were significantly greater than the recommended level (P
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- 2024
10. Propensity Score Augmentation in Matching-based Estimation of Causal Effects
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Ulloa-Pérez, Ernesto, Carone, Marco, and Luedtke, Alex
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Statistics - Methodology ,Mathematics - Statistics Theory - Abstract
When assessing the causal effect of a binary exposure using observational data, confounder imbalance across exposure arms must be addressed. Matching methods, including propensity score-based matching, can be used to deconfound the causal relationship of interest. They have been particularly popular in practice, at least in part due to their simplicity and interpretability. However, these methods can suffer from low statistical efficiency compared to many competing methods. In this work, we propose a novel matching-based estimator of the average treatment effect based on a suitably-augmented propensity score model. Our procedure can be shown to have greater statistical efficiency than traditional matching estimators whenever prognostic variables are available, and in some cases, can nearly reach the nonparametric efficiency bound. In addition to a theoretical study, we provide numerical results to illustrate our findings. Finally, we use our novel procedure to estimate the effect of circumcision on risk of HIV-1 infection using vaccine efficacy trial data.
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- 2024
11. The cumulant Green's functions method for the single impurity Anderson model
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Sobreira, T. M., Puel, T. O., Manya, M. A., Ulloa, S. E., Martins, G. B., Silva-Valencia, J., Lira, R. N., and Figueira, M. S.
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Condensed Matter - Strongly Correlated Electrons - Abstract
Using the cumulant Green's functions method (CGFM), we study the single impurity Anderson model (SIAM). The CGFM starting point is a diagonalization of the SIAM Hamiltonian expressed in a semi-chain form, containing N sites, viz., a correlated site (simulating an impurity) connected to the remaining N-1 uncorrelated conduction-electron sites. An exact solution can be obtained since the complete system has few sites. That solution is employed to calculate the atomic Green's functions and the approximate cumulants used to obtain the impurity and conduction Green's functions for the SIAM, and no self-consistency loop is required. We calculated the density of states, the Friedel sum rule, and the impurity occupation number, all benchmarked against results from the numerical renormalization group (NRG). One of the main insights obtained is that, at very low temperatures, only four atomic transitions contribute to generating the entire SIAM density of states, regardless of the number of sites in the chain and the model's parameters and different regimes: Empty orbital, mixed-valence, and Kondo. We also pointed out the possibilities of the CGFM as a valid alternative to describe strongly correlated electron systems like the Hubbard and t-J models, the periodic Anderson model, the Kondo and Coqblin-Schrieffer models, and their variants., Comment: 11 pages and 8 figures
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- 2024
12. Exploring the ability of the Deep Ritz Method to model strain localization as a sharp discontinuity
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León, Omar, Rivera, Víctor, Vázquez-Patiño, Angel, Ulloa, Jacinto, and Samaniego, Esteban
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Computer Science - Machine Learning - Abstract
We present an exploratory study of the possibilities of the Deep Ritz Method (DRM) for the modeling of strain localization in solids as a sharp discontinuity in the displacement field. For this, we use a regularized strong discontinuity kinematics within a variational setting for elastoplastic solids. The corresponding mathematical model is discretized using Artificial Neural Networks (ANNs). The architecture takes care of the kinematics, while the variational statement of the boundary value problem is taken care of by the loss function. The main idea behind this approach is to solve both the equilibrium problem and the location of the localization band by means of trainable parameters in the ANN. As a proof of concept, we show through both 1D and 2D numerical examples that the computational modeling of strain localization for elastoplastic solids within the framework of DRM is feasible., Comment: The article has 22 pages including 14 figures and 26 references. The manuscript was prepared for submission to Archives of Computational Methods in Engineering
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- 2024
13. Googling the Big Lie: Search Engines, News Media, and the US 2020 Election Conspiracy
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de León, Ernesto, Makhortykh, Mykola, Urman, Aleksandra, and Ulloa, Roberto
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Computer Science - Information Retrieval ,Computer Science - Computers and Society - Abstract
The conspiracy theory that the US 2020 presidential election was fraudulent - the Big Lie - remained a prominent part of the media agenda months after the election. Whether and how search engines prioritized news stories that sought to thoroughly debunk the claims, provide a simple negation, or support the conspiracy is crucial for understanding information exposure on the topic. We investigate how search engines provided news on this conspiracy by conducting a large-scale algorithm audit evaluating differences between three search engines (Google, DuckDuckGo, and Bing), across three locations (Ohio, California, and the UK), and using eleven search queries. Results show that simply denying the conspiracy is the largest debunking strategy across all search engines. While Google has a strong mainstreaming effect on articles explicitly focused on the Big Lie - providing thorough debunks and alternative explanations - DuckDuckGo and Bing display, depending on the location, a large share of articles either supporting the conspiracy or failing to debunk it. Lastly, we find that niche ideologically driven search queries (e.g., "sharpie marker ballots Arizona") do not lead to more conspiracy-supportive material. Instead, content supporting the conspiracy is largely a product of broader ideology-agnostic search queries (e.g., "voter fraud 2020")., Comment: 40 pages
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- 2024
14. The Standard Model CP Violation is Enough
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Elor, Gilly, Houtz, Rachel, Ipek, Seyda, and Ulloa, Martha
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High Energy Physics - Phenomenology ,High Energy Physics - Experiment - Abstract
Is the Standard Model Charge-Parity (CP) violation ever enough to generate the observed baryon asymmetry? Yes! We introduce a mechanism of baryogenesis (and dark matter production) that can generate the entire observed baryon asymmetry of the Universe using $\textit{only}$ the CP violation within Standard Model systems -- a f\^ete which no other mechanism currently proposed can achieve. Baryogenesis proceeds through a Mesogenesis scenario but with well motivated additional dark sector dynamics: a $\textit{morphon}$ field generates present day mass contributions for the particle mediating the decay responsible for baryogenesis. The effect is an enhancement of baryon production whilst evading present day collider constraints. The CP violation comes entirely from Standard Model contributions to neutral meson systems. Meanwhile, the dark dynamics generate gravitational waves that may be searched for with current and upcoming Pulsar Timing Arrays, as we demonstrate with an example. This mechanism, $\textit{Mesogenesis with a Morphing Mediator}$, motivates probing a new parameter space as well as improving the sensitivity of existing Mesogenesis searches at hadron and electron colliders., Comment: 5+1 pages, 3 figures
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- 2024
15. Exploring the Coexistence of Spin States in [Fe-(tpy-ph)$_2$]$^{2+}$ Complexes on Au(111) using ab initio calculations
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Dandu, Naveen K., Lee, Alex Taekyung, Ulloa, Sergio, Curtiss, Larry, Hla, Saw Wai, and Ngo, Anh T.
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Condensed Matter - Materials Science ,Condensed Matter - Strongly Correlated Electrons - Abstract
In this work, we systematically study the electronic structure and stability of spin states of the [Fe-(tpy-ph)$_2$]$^{2+}$ molecule in both gas phase and on a Au(111) substrate using density functional theory +U (DFT+U) calculations. We find that the stability of the Fe$^{2+}$ ion's spin states is significantly influenced by the Hubbard U parameter. In the gas phase, the low-spin (LS, S=0) state is found to be energetically favorable for U(Fe) $\leq$ 3 eV, whereas the high-spin (HS, S=2) state is stabilized for U(Fe) > 3 eV. Interaction with the Au(111) substrate is found to elevate the critical U for the spin-state transition to 3.5 eV. Additionally, we perform L-edge X-ray absorption spectroscopy (XAS) calculations based on time-dependent DFT (TD-DFT) for both HS and LS states. The calculated XAS suggests that the HS state more closely aligns with the experimental observations, indicating the potential coexistence of the HS state as the initial state during the X-ray excitation process. These findings enrich our understanding of spin-state dynamics in [Fe-(tpy-ph)$_2$]$^{2+}$., Comment: 21 pages, 5 figures, 3 tables
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- 2024
16. Assessing In-context Learning and Fine-tuning for Topic Classification of German Web Data
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Schelb, Julian, Ulloa, Roberto, and Spitz, Andreas
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Computer Science - Computation and Language - Abstract
Researchers in the political and social sciences often rely on classification models to analyze trends in information consumption by examining browsing histories of millions of webpages. Automated scalable methods are necessary due to the impracticality of manual labeling. In this paper, we model the detection of topic-related content as a binary classification task and compare the accuracy of fine-tuned pre-trained encoder models against in-context learning strategies. Using only a few hundred annotated data points per topic, we detect content related to three German policies in a database of scraped webpages. We compare multilingual and monolingual models, as well as zero and few-shot approaches, and investigate the impact of negative sampling strategies and the combination of URL & content-based features. Our results show that a small sample of annotated data is sufficient to train an effective classifier. Fine-tuning encoder-based models yields better results than in-context learning. Classifiers using both URL & content-based features perform best, while using URLs alone provides adequate results when content is unavailable.
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- 2024
17. A Method for Calculating Attenuation in Creeping Materials
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Maor, Ron, Badt, Nir Z., Ulloa, Hugo N., and Goldsby, David L.
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Physics - Geophysics ,Physics - Atmospheric and Oceanic Physics - Abstract
The phase lag between an applied forcing and a response to that forcing is a fundamen tal parameter in geophysical signal processing. For solid deforming materials, the phase lag between an oscillatory applied stress and the resulting strain response encapsulates information about the dynamical behavior of materials and attenuation. The phase lag is not directly measured and must be extracted through multiple steps by carefully comparing two time-series signals. The extracted value of the phase lag is highly sensitive to the analysis method, and often there are no comparable values to increase confidence in the calculated results. In this study, we propose a method for extracting the phase lag between two signals when either one or both include an underlying nonlinear trend, which is very common when measuring attenuation in creeping materials. We demonstrate the robustness of the method by analyzing artificial signals with known phases and quantifying their absolute and relative errors. We apply the method to two experimental datasets and compare our results with those of previous studies
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- 2024
18. Efficacy and safety of autologous whole blood clot in diabetic foot ulcers: a randomised controlled trial
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Snyder, Robert, Nouvong, Aksone, Ulloa, Jesus, Wahab, Naz, Treadwell, Terry, Bruwer, Febe, Naude, Liezl, McGuire, James, Reyzelman, Alexander M, Graham, Timothy, Team:, AWBC Research, Lessing, Rene, Lullove, Eric, Ozker, Emre, Pham, Hau T, Pasternac, Michael, and Cohen, Shira
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Biomedical and Clinical Sciences ,Clinical Sciences ,Clinical Research ,Clinical Trials and Supportive Activities ,Diabetes ,Humans ,Diabetic Foot ,Male ,Female ,Middle Aged ,Wound Healing ,Prospective Studies ,Aged ,Turkey ,South Africa ,Treatment Outcome ,United States ,Blood Transfusion ,Autologous ,AWBC Research Team: ,autologous ,blood ,cell-based therapy ,diabetic ,foot ulcer ,randomised controlled trial ,tissue-based therapy ,wound ,wound care ,wound dressing ,wound healing ,Nursing ,Clinical sciences - Abstract
ObjectiveDiabetic foot ulcers (DFUs) present a significant global health challenge, resulting in high morbidity and economic costs. Current available treatments often fail to achieve satisfactory healing rates, highlighting the need for novel therapies. This study evaluated the safety and efficacy of a novel autologous whole blood clot (AWBC)-a blood-based, biodegradable provisional matrix-in conjunction with standard of care (SoC) when compared to SoC alone in the treatment of hard-to-heal DFUs.MethodA multicentre, prospective, blinded assessor, randomised controlled trial was conducted at 16 sites across the US, South Africa and Turkey. A cohort of patients with hard-to-heal DFUs was enrolled and randomised to either the AWBC group or the control group. The primary endpoint was complete wound closure at 12 weeks, while secondary endpoints included time to heal and percentage area reduction (PAR) at four and eight weeks. Data were analysed using both intention-to-treat (ITT) and per-protocol (PP) populations.ResultsThe cohort included 119 patients. AWBC treatment resulted in a significantly higher healing rate compared to the control in both ITT (41% versus 15%, respectively; p=0.002) and PP populations (51% versus 18%, respectively; p=0.0075). AWBC treatment also resulted in a shorter mean time to heal and higher durability of wound closure. Safety analysis showed a similar incidence of adverse events (AEs) between groups, with no device-related AEs.ConclusionThe AWBC system, by modulating the wound microenvironment and providing a functional extracellular matrix, offered a promising new approach to treating hard-to-heal DFUs, demonstrating superior healing outcomes compared to SoC alone in this study.
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- 2024
19. Multisystem inflammatory syndrome in children across 16 Latin American countries: A multicenter study from the REKAMLATINA Network.
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García-Silva, Jimena, Ulloa-Gutierrez, Rolando, Ivankovich-Escoto, Gabriela, Yamazaki-Nakashimada, Marco, Faugier-Fuentes, Enrique, Del Águila, Olguita, Camacho-Moreno, German, Estripeaut, Dora, Gutiérrez, Iván, Castillo-Bustamante, David, Luciani, Kathia, Fabi, Mariana, Espada, Graciela, Álvarez-Olmos, Martha, Silfa, Claribel, Pérez-Camacho, Paola, Duarte-Passos, Saulo, Cervi, Maria, Martínez-Ramírez, Rogelio, Cantillano, Edwin, Llamas-Guillén, Beatriz, Velásquez-Méndez, Mónica, Saltigeral-Simental, Patricia, Criales, Javier, Fernández-Sarmiento, Jaime, Chacon-Cruz, Enrique, García-Domínguez, Miguel, Aguilar, Karla, Villarreal-Treviño, Ana, and Tremoulet, Adriana
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Latin America ,Multisystem Inflammatory Syndrome in Children (MIS-C) - Abstract
OBJECTIVES: Our aim was to describe the epidemiology and outcomes of multisystem inflammatory syndrome in children (MIS-C) in Latin America. METHODS: We conducted an observational, retrospective, and prospective multicenter study that gathered information from 84 participating centers across 16 Latin American countries between August 1, 2020 and June 30, 2022. RESULTS: Of the 1239 reported children with MIS-C, 84.18% were previously healthy. The most frequent clinical manifestation in our studied population was abdominal pain (N = 804, 64.9%), followed by conjunctival injection (N = 784, 63.3%). The median duration of fever at the time of hospital admission was 5 days and a significant number of subjects required admission to an intensive care unit (N = 589, 47.5%). Most of the subjects (N = 1096, 88.7%) were treated with intravenous immunoglobulin, whereas 76.7% (N = 947) were treated with steroids, of whom 10.6% (N = 100) did not receive intravenous immunoglobulin. The death rate attributed to MIS-C was 4.88%, with a rate of 3.39% for those initially diagnosed with MIS-C and 8.85% for those whose admission diagnosis was not MIS-C (P
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- 2024
20. Exploring Outcomes for Hispanic Patients Undergoing Open Bypass in the BEST-CLI Trial
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Ulloa, Jesus G, Alabi, Olamide, Farber, Alik, Menard, Matthew, Kernoodle, Amber, Moreira, Carla C, Kirksey, Lee, Malas, Mahmoud, Hamouda, Mohammed, and Rowe, Vincent L
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Biomedical and Clinical Sciences ,Cardiovascular Medicine and Haematology ,Clinical Sciences ,Medical and Health Sciences ,Cardiovascular System & Hematology ,Cardiovascular medicine and haematology ,Clinical sciences - Published
- 2024
21. Clonal hematopoiesis and inflammation in the vasculature: CHIVE, a prospective, longitudinal clonal hematopoiesis cohort and biorepository.
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Shannon, Morgan, Heimlich, J, Olson, Sydney, Debevec, Ariana, Copeland, Zachary, Kishtagari, Ashwin, Vlasschaert, Caitlyn, Snider, Christina, Silver, Alexander, Brown, Donovan, Spaulding, Travis, Bhatta, Manasa, Pugh, Kelly, Stockton, Shannon, Ulloa, Jessica, Xu, Yaomin, Baljevic, Muhamed, Moslehi, Javid, Jahangir, Eiman, Ferrell, P, Slosky, David, Bick, Alexander, and Savona, Michael
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Humans ,Clonal Hematopoiesis ,Inflammation ,Prospective Studies ,Female ,Male ,Middle Aged ,Aged ,Registries ,Hematologic Neoplasms ,Mutation ,Adult - Abstract
Clonal hematopoiesis (CH) is an age-associated phenomenon leading to an increased risk of both hematologic malignancy and nonmalignant organ dysfunction. Increasingly available genetic testing has made the incidental discovery of CH clinically common yet evidence-based guidelines and effective management strategies to prevent adverse CH health outcomes are lacking. To address this gap, the prospective CHIVE (clonal hematopoiesis and inflammation in the vasculature) registry and biorepository was created to identify and monitor individuals at risk, support multidisciplinary CH clinics, and refine taxonomy and standards of practice for CH risk mitigation. Data from the first 181 patients enrolled in this prospective registry recapitulate the molecular epidemiology of CH from biobank-scale retrospective studies, with DNMT3A, TET2, ASXL1, and TP53 as the most commonly mutated genes. Blood counts across all hematopoietic lineages trended lower in patients with CH. In addition, patients with CH had higher rates of end organ dysfunction, in particular chronic kidney disease. Among patients with CH, variant allele frequency was independently associated with the presence of cytopenias and progression to hematologic malignancy, whereas other common high-risk CH clone features were not clear. Notably, accumulation of multiple distinct high-risk clone features was also associated with cytopenias and hematologic malignancy progression, supporting a recently published CH risk score. Surprisingly, ∼30% of patients enrolled in CHIVE from CH clinics were adjudicated as not having clonal hematopoiesis of indeterminate potential, highlighting the need for molecular standards and purpose-built assays in this field. Maintenance of this well-annotated cohort and continued expansion of CHIVE to multiple institutions are underway and will be critical to understanding how to thoughtfully care for this patient population.
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- 2024
22. Fracture and size effect in mechanical metamaterials
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Ulloa, J., Ariza, M. P., Andrade, J. E., and Ortiz, M.
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Physics - Classical Physics ,Physics - Applied Physics - Abstract
We resort to variational methods to evaluate the asymptotic behavior of fine metamaterials as a function of cell size. To zeroth order, the metamaterial behaves as a micropolar continuum with both displacement and rotation degrees of freedom, but exhibits linear-elastic fracture mechanics scaling and therefore no size effect. To higher order, the overall energetics of the metastructure can be characterized explicitly in terms of the solution of the zeroth-order continuum problem by the method of {\Gamma}-expansion. We present explicit expressions of the second-order correction for octet frames. As an application, we evaluate the compliance of double-cantilever octet specimens to second order and use the result to elucidate the dependence of the apparent toughness of the specimen on cell size. The analysis predicts the discreteness of the metamaterial lattice to effectively shield the crack-tip, a mechanism that we term lattice shielding. The theory specifically predicts anti-shielding, i. e., coarser is weaker, in agreement with recent experimental observations.
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- 2024
23. Machine-Learning-Enabled Fast Optical Identification and Characterization of 2D Materials
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Leger, Polina A., Ramesh, Aditya, Ulloa, Talianna, and Wu, Yingying
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Condensed Matter - Materials Science - Abstract
Two-dimensional materials are a class of atomically thin materials with assorted electronic and quantum properties. Accurate identification of layer thickness, especially for a single monolayer, is crucial for their characterization. This characterization process, however, is often time-consuming, requiring highly skilled researchers and expensive equipment like atomic force microscopy. This project aims to streamline the identification process by using machine learning to analyze optical images and quickly determine layer thickness. In this paper, we evaluate the performance of three machine learning models -- SegNet, 1D U-Net, and 2D U-Net -- in accurately identifying monolayers in microscopic images. Additionally, we explore labeling and image processing techniques to determine the most effective method for identifying layer thickness in this class of materials., Comment: 21 pages, 6 figures
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- 2024
24. Tuning electronic pairing by uniaxial strain in kagome lattices
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Mojarro, M. A. and Ulloa, Sergio E.
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Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Superconductivity - Abstract
We study the interplay of attractive electron interactions and topological states in strained kagome lattices with spin-orbit coupling via a Hubbard Hamiltonian in the mean-field approximation. In the unstrained lattice, there is a topological phase transition from a quantum spin Hall state to a charge density wave (CDW) with increasing interaction strength. Upon applying a uniform uniaxial strain to the lattice, we find a new phase with coexisting CDWs and topological states. For increasing interaction strength or strain, the system is driven into a pure CDW, signaling topological phase transitions. The directionality (nematicity) of the CDW is controlled by the direction of the applied strain. When $s$ wave electronic pairing is allowed, the system develops a superconducting order beyond a threshold attraction, which is totally suppressed by the onset of a CDW with increasing interaction. Most interestingly, moderate strain allows the coexistence of superconductivity and CDWs for a range of interaction values. This illustrates how electronic interactions and single-particle topological structures compete to create unusual correlated phases in kagome systems.
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- 2024
25. Energetics of particle-size segregation
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Trewhela, Tomás and Ulloa, Hugo N.
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Condensed Matter - Soft Condensed Matter ,Physics - Fluid Dynamics ,Physics - Geophysics - Abstract
We introduce a continuum framework for the energetics of particle-size segregation in bidisperse granular flows. Building on continuum segregation equations and a recent segregation flux model, the proposed framework offers general analytical expressions to study the physics of granular flows from a mechanical energy perspective. To demonstrate the framework's applicability, we examined the energetics in shear-driven flows. Numerical experiments with varying frictional coefficients and particle-size ratios revealed two distinct phases in the associated energetics with particle segregation and diffusive remixing, and that the potential energy to the kinetic energy ratio in the steady state follows the scaling relationship $\hat{E}^{(s)}_{gp} / \hat{E}^{(s)}_{k} \propto Pe^{-1/2}_{sr}$ for $0.4 \leq Pe_{sr} \leq 300$, the segregation-rheology P\'eclet number. Our findings hint that the bulk segregation-mixing state can be predicted and controlled using $Pe_{sr}$, determined from known system parameters, providing a impactful tool for engineering and geophysical applications., Comment: 10 pages, 3 figures
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- 2024
26. Magnetic response and antiferromagnetic correlations in strained kagome ribbons
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Costa, R. F. P., Vernek, E., and Ulloa, S. E.
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Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Materials Science - Abstract
We study the physics of the strong-coupling Hubbard model in a kagome lattice ribbon under mechanical tension and half-filling. It is known that in the absence of strain, the lattice symmetry of the system and strong electronic interactions induce magnetic frustration. As uniaxial strain is applied, the ribbon exhibits various configurations with energy oscillations that depend on the direction of the strain axis. The ground states are obtained by density-matrix renormalization-group calculations. We find that the system is characterized by strong antiferromagnetic bonds distributed throughout the lattice in directions and patterns that depend on strain directions and may coexist with easily polarizable sites that are only weakly correlated to their neighbors. We identify frustration and correlation measures that follow the strain and interaction dependence of the system well. These results illustrate that strain-dependent magnetic susceptibility could be explored experimentally to help probe the role of symmetry and interactions in these systems., Comment: 9 pages, 10 figures
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- 2024
- Full Text
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27. Effects of Magnetic Anisotropy on 3-Qubit Antiferromagnetic Thermal Machines
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Castorene, Bastian, Peña, Francisco J., Norambuena, Ariel, Ulloa, Sergio E., Araya, Cristobal, and Vargas, Patricio
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Condensed Matter - Statistical Mechanics ,Quantum Physics - Abstract
This study investigates the anisotropic effects on a system of three qubits with chain and ring topology, described by the antiferromagnetic Heisenberg XXX model subjected to a homogeneous magnetic field. We explore the Stirling and Otto cycles and find that easy-axis anisotropy significantly enhances engine efficiency across all cases. At low temperatures, the ring configuration outperforms the chain on both work and efficiency during the Stirling cycle. Additionally, in both topologies, the Stirling cycle achieves Carnot efficiency with finite work at quantum critical points. In contrast, the quasistatic Otto engine also reaches Carnot efficiency at these points but yields no useful work. Notably, the Stirling cycle exhibits all thermal operational regimes engine, refrigerator, heater, and accelerator unlike the quasistatic Otto cycle, which functions only as an engine or refrigerator.
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- 2024
28. Active Carpets in floating viscous films
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Barros, Felipe A., Ulloa, Hugo N., Aguayo, Gabriel, Mathijssen, Arnold J. T. M., and Guzmán-Lastra, Francisca
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Physics - Fluid Dynamics ,Condensed Matter - Soft Condensed Matter - Abstract
Earth's aquatic environments are inherently stratified layered systems where interfaces between layers serve as ecological niches for microbial swimmers, forming colonies known as Active Carpet (AC). Previous theoretical studies have explored the hydrodynamic fluctuations exerted by ACs in semi-infinite fluid media, demonstrating their capability to enhance thermal diffusion and mass transport in aquatic systems. Yet, little is understood about the fluid dynamics and impact of ACs residing in confined layered environments, like slicks floating on water bodies. In this study, we report novel solutions for the hydrodynamic fluctuations induced by ACs geometrically confined between a free surface and a fluid-fluid interface characterized by a jump in fluid viscosity. Combining theory and numerical experiments, we investigate the topology of the biogenic hydrodynamic fluctuations in a confined, thin fluid environment. We reveal that within this thin layer, ACs gives shape to three characteristic regions: Region I is the closest zone to the AC and the fluid-fluid interface, where hydrodynamic fluctuations are dominantly vertical; Region II is further up from the AC and is characterized by isotropic hydrodynamic fluctuations; Region III is the furthest region, near the free surface and is dominated by horizontal flow fluctuations. We demonstrate that the extent of these regions depends strongly on the degree of confinement, i.e. the layer thickness and the strength of the viscosity jump. Lastly, we show that confinement fosters the emergence of large-scale flow structures within the layer housing the ACs--not previously reported. Our findings shed light on the complex interplay between confinement and hydrodynamics in floating viscous film biological systems, providing valuable insights with implications spanning from ecological conservation to bio-inspired engineering.
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- 2024
29. First constraints on the $L_\mu-L_\tau$ explanation of the muon $g-2$ anomaly from NA64-$e$ at CERN
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Andreev, Yu. M., Antonov, A., Banerjee, D., Oberhauser, B. Banto, Bernhard, J., Bisio, P., Celentano, A., Charitonidis, N., Cooke, D., Crivelli, P., Depero, E., Dermenev, A. V., Donskov, S. V., Dusaev, R. R., Enik, T., Frolov, V. N., Gardikiotis, A., Gninenko, S. N., Hösgen, M., Kachanov, V. A., Kambar, Y., Karneyeu, A. E., Kekelidze, G., Ketzer, B., Kirpichnikov, D. V., Kirsanov, M. M., Kolosov, V. N., Gertsenberger, S. V., Girod, S., Kasianova, E. A., Kramarenko, V. A., Kravchuk, L. V., Krasnikov, N. V., Kuleshov, S. V., Lyubovitskij, V. E., Lysan, V., Marini, A., Marsicano, L., Matveev, V. A., Fredes, R. Mena, Yanssen, R. Mena, Bueno, L. Molina, Mongillo, M., Peshekhonov, D. V., Polyakov, V. A., Radics, B., Salamatin, K., Samoylenko, V. D., Sieber, H., Shchukin, D., Soto, O., Tikhomirov, V. O., Tlisova, I., Toropin, A. N., Tuzi, M., Ulloa, P., Volkov, P. V., Volkov, V. Yu., Voronchikhin, I. V., Zamora-Saá, J., and Zhevlako, A. S.
- Subjects
High Energy Physics - Experiment ,High Energy Physics - Phenomenology - Abstract
The inclusion of an additional $U(1)$ gauge $L_\mu-L_\tau$ symmetry would release the tension between the measured and the predicted value of the anomalous muon magnetic moment: this paradigm assumes the existence of a new, light $Z^\prime$ vector boson, with dominant coupling to $\mu$ and $\tau$ leptons and interacting with electrons via a loop mechanism. The $L_\mu-L_\tau$ model can also explain the Dark Matter relic abundance, by assuming that the $Z'$ boson acts as a "portal" to a new Dark Sector of particles in Nature, not charged under known interactions. In this work we present the results of the $Z'$ search performed by the NA64-$e$ experiment at CERN SPS, that collected $\sim 9\times10^{11}$ 100 GeV electrons impinging on an active thick target. Despite the suppressed $Z'$ production yield with an electron beam, NA64-$e$ provides the first accelerator-based results excluding the $g-2$ preferred band of the $Z'$ parameter space in the 1 keV $ < m_{Z'} \lesssim 2$ MeV range, in complementarity with the limits recently obtained by the NA64-$\mu$ experiment with a muon beam., Comment: 15 pages, 5 figures. New version with extended exclusion limits down to 1 keV in Z' mass
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- 2024
30. Post-activation performance enhancement methods in team sport athletes: a systematic review with meta-analysis
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Ulloa-Sánchez, Paul, Hernández-Elizondo, Jessenia, Thapa, Rohit K., Sortwell, Andrew, and Ramirez-Campillo, Rodrigo
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- 2024
- Full Text
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31. Potentiation of Motor Adaptation Via Cerebellar tACS: Characterization of the Stimulation Frequency
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Figueroa-Taiba, Paulo, Álvarez-Ruf, Joel, Ulloa, Paulette, Bruna-Melo, Trinidad, Espinoza-Maraboli, Liam, Burgos, Pablo Ignacio, and Mariman, Juan J
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- 2024
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32. Regulation of Behavior Analysis in 15 Countries of Latin America: Assessing the Challenges and Opportunities for Implementation of the Science
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de los Santos, Mariana, Hernández Eslava, Varsovia, Ávila, Miguel, Alarcón Moya, Estefanía C., Scolari, Carola, Ulloa, Gabriella, Jimenez-Gomez, Corina, Febres Cordero, Diana, Parejo, Valeria, Chavez-Askins, Mapy, Pezzotti, Gricel, Vergara, Diana, Urcuyo, Beatriz, Argueta, Luis Rafael, Arroyave Tefel, Jessie, Morhaim Esquenazi de Sfadia, Rosita, Ríos Arroyo, Ethel I., Padilla Dalmau, Yaniz C., Gilbert, Monica, and Rodríguez, Alejandra
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- 2024
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33. Refuting the hypothesis of Centinelan extinction at its place of origin
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White, Dawson M., Pitman, Nigel C. A., Feeley, Kenneth J., Rivas-Torres, Gonzalo, Bravo-Sánchez, Santiago, Sánchez-Parrales, Francisco, Clark, John L., Ulloa Ulloa, Carmen, Cornejo, Xavier, Couvreur, Thomas L. P., Peñafiel, Marcia, Benavides, Gladys, Bonifaz, Carmita, Cerón, Juan Carlos, Fernández, Andrea, Fortier, Riley P., Navas-Muñoz, Daniel, Rojas M, Verónica, Zapata, J. Nicolás, Williams, Justin, and Guevara-Andino, Juan Ernesto
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- 2024
- Full Text
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34. Evaluating the glymphatic system via magnetic resonance diffusion tensor imaging along the perivascular spaces in brain tumor patients
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Villacis, Gabriela, Schmidt, Aileen, Rudolf, Justus C., Schwenke, Hannes, Küchler, Jan, Schramm, Peter, and Ulloa, Patricia
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- 2024
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35. Knowledge, attitudes, and perceived Ethics regarding the use of ChatGPT among generation Z university students
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Acosta-Enriquez, Benicio Gonzalo, Arbulú Ballesteros, Marco Agustín, Arbulu Perez Vargas, Carmen Graciela, Orellana Ulloa, Milca Naara, Gutiérrez Ulloa, Cristian Raymound, Pizarro Romero, Johanna Micaela, Gutiérrez Jaramillo, Néstor Daniel, Cuenca Orellana, Héctor Ulises, Ayala Anzoátegui, Diego Xavier, and López Roca, Carlos
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- 2024
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36. The UNESCO OER Recommendation: Some Observations from the ICDE OER Advocacy Committee
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Ossiannilsson, Ebba, Cazarez, Rosa Leonor Ulloa, de Gusmão, Cristine Martins Gomes, Zhang, Xiangyang, Blomgren, Constance, Chaplin-Cheyne, Trish, and Burgos, Daniel
- Abstract
In this article, ambassadors of the International Council for Open and Distance Education (ICDE) Open Educational Resources (OER) Advocacy Committee (OERAC) provide a snapshot of regional and global Open Educational Resources (OER)initiatives. This committee has been active since 2017 with membership renewed biannually. The ambassadors work to further OER awareness and understanding, to increase global recognition of OER, and provide policy support for the acceptance and application of OER. This overview highlights national and regional initiatives associated with the UNESCO OER recommendation and the five action areas that include: building capacity and leveraging OER; developing supporting policies; ensuring equity and effectiveness; encouraging sustainable OER model development; and, promoting and facilitating international collaboration. In addition, monitoring and evaluation of the action areas are suggested to be prioritized. This overview is not exhaustive, and much work remains to implement the OER Recommendation at scale, maximize its implementation, connect these recommendations to the United Nation's Sustainable Development Goals (SDGs), along with the futures of education with a new social contract for education, individuals, and the planet.
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- 2023
37. Improving the quality of individual-level online information tracking: challenges of existing approaches and introduction of a new content- and long-tail sensitive academic solution
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Adam, Silke, Makhortykh, Mykola, Maier, Michaela, Aigenseer, Viktor, Urman, Aleksandra, Lopez, Teresa Gil, Christner, Clara, de León, Ernesto, and Ulloa, Roberto
- Subjects
Computer Science - Computers and Society - Abstract
This article evaluates the quality of data collection in individual-level desktop information tracking used in the social sciences and shows that the existing approaches face sampling issues, validity issues due to the lack of content-level data and their disregard of the variety of devices and long-tail consumption patterns as well as transparency and privacy issues. To overcome some of these problems, the article introduces a new academic tracking solution, WebTrack, an open source tracking tool maintained by a major European research institution. The design logic, the interfaces and the backend requirements for WebTrack, followed by a detailed examination of strengths and weaknesses of the tool, are discussed. Finally, using data from 1185 participants, the article empirically illustrates how an improvement in the data collection through WebTrack leads to new innovative shifts in the processing of tracking data. As WebTrack allows collecting the content people are exposed to on more than classical news platforms, we can strongly improve the detection of politics-related information consumption in tracking data with the application of automated content analysis compared to traditional approaches that rely on the list-based identification of news., Comment: 73 pages
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- 2024
38. Data-driven micromorphic mechanics for materials with strain localization
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Ulloa, Jacinto, Stainier, Laurent, Ortiz, Michael, and Andrade, José E.
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Mathematics - Numerical Analysis - Abstract
This paper explores the role of generalized continuum mechanics, and the feasibility of model-free data-driven computing approaches thereof, in solids undergoing failure by strain localization. Specifically, we set forth a methodology for capturing material instabilities using data-driven mechanics without prior information regarding the failure mode. We show numerically that, in problems involving strain localization, the standard data-driven framework for Cauchy/Boltzmann continua fails to capture the length scale of the material, as expected. We address this shortcoming by formulating a generalized data-driven framework for micromorphic continua that effectively captures both stiffness and length-scale information, as encoded in the material data, in a model-free manner. These properties are exhibited systematically in a one-dimensional softening bar problem and further verified through selected plane-strain problems., Comment: Published version; minor errata correction
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- 2024
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39. Harmful algal bloom forecasting. A comparison between stream and batch learning
- Author
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Molares-Ulloa, Andres, Rocruz, Elisabet, Rivero, Daniel, Padin, Xosé A., Nolasco, Rita, Dubert, Jesús, and Fernandez-Blanco, Enrique
- Subjects
Computer Science - Machine Learning ,Computer Science - Artificial Intelligence - Abstract
Diarrhetic Shellfish Poisoning (DSP) is a global health threat arising from shellfish contaminated with toxins produced by dinoflagellates. The condition, with its widespread incidence, high morbidity rate, and persistent shellfish toxicity, poses risks to public health and the shellfish industry. High biomass of toxin-producing algae such as DSP are known as Harmful Algal Blooms (HABs). Monitoring and forecasting systems are crucial for mitigating HABs impact. Predicting harmful algal blooms involves a time-series-based problem with a strong historical seasonal component, however, recent anomalies due to changes in meteorological and oceanographic events have been observed. Stream Learning stands out as one of the most promising approaches for addressing time-series-based problems with concept drifts. However, its efficacy in predicting HABs remains unproven and needs to be tested in comparison with Batch Learning. Historical data availability is a critical point in developing predictive systems. In oceanography, the available data collection can have some constrains and limitations, which has led to exploring new tools to obtain more exhaustive time series. In this study, a machine learning workflow for predicting the number of cells of a toxic dinoflagellate, Dinophysis acuminata, was developed with several key advancements. Seven machine learning algorithms were compared within two learning paradigms. Notably, the output data from CROCO, the ocean hydrodynamic model, was employed as the primary dataset, palliating the limitation of time-continuous historical data. This study highlights the value of models interpretability, fair models comparison methodology, and the incorporation of Stream Learning models. The model DoME, with an average R2 of 0.77 in the 3-day-ahead prediction, emerged as the most effective and interpretable predictor, outperforming the other algorithms.
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- 2024
40. Hybrid Machine Learning techniques in the management of harmful algal blooms impact
- Author
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Molares-Ulloa, Andres, Rivero, Daniel, Ruiz, Jesus Gil, Fernandez-Blanco, Enrique, and de-la-Fuente-Valentín, Luis
- Subjects
Computer Science - Machine Learning ,Quantitative Biology - Quantitative Methods - Abstract
Harmful algal blooms (HABs) are episodes of high concentrations of algae that are potentially toxic for human consumption. Mollusc farming can be affected by HABs because, as filter feeders, they can accumulate high concentrations of marine biotoxins in their tissues. To avoid the risk to human consumption, harvesting is prohibited when toxicity is detected. At present, the closure of production areas is based on expert knowledge and the existence of a predictive model would help when conditions are complex and sampling is not possible. Although the concentration of toxin in meat is the method most commonly used by experts in the control of shellfish production areas, it is rarely used as a target by automatic prediction models. This is largely due to the irregularity of the data due to the established sampling programs. As an alternative, the activity status of production areas has been proposed as a target variable based on whether mollusc meat has a toxicity level below or above the legal limit. This new option is the most similar to the actual functioning of the control of shellfish production areas. For this purpose, we have made a comparison between hybrid machine learning models like Neural-Network-Adding Bootstrap (BAGNET) and Discriminative Nearest Neighbor Classification (SVM-KNN) when estimating the state of production areas. The study has been carried out in several estuaries with different levels of complexity in the episodes of algal blooms to demonstrate the generalization capacity of the models in bloom detection. As a result, we could observe that, with an average recall value of 93.41% and without dropping below 90% in any of the estuaries, BAGNET outperforms the other models both in terms of results and robustness.
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- 2024
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41. Machine Learning in management of precautionary closures caused by lipophilic biotoxins
- Author
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Molares-Ulloa, Andres, Fernandez-Blanco, Enrique, Pazos, Alejandro, and Rivero, Daniel
- Subjects
Computer Science - Artificial Intelligence - Abstract
Mussel farming is one of the most important aquaculture industries. The main risk to mussel farming is harmful algal blooms (HABs), which pose a risk to human consumption. In Galicia, the Spanish main producer of cultivated mussels, the opening and closing of the production areas is controlled by a monitoring program. In addition to the closures resulting from the presence of toxicity exceeding the legal threshold, in the absence of a confirmatory sampling and the existence of risk factors, precautionary closures may be applied. These decisions are made by experts without the support or formalisation of the experience on which they are based. Therefore, this work proposes a predictive model capable of supporting the application of precautionary closures. Achieving sensitivity, accuracy and kappa index values of 97.34%, 91.83% and 0.75 respectively, the kNN algorithm has provided the best results. This allows the creation of a system capable of helping in complex situations where forecast errors are more common.
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- 2024
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42. Heavy element abundances in Galactic Globular Clusters
- Author
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Schiappacasse-Ulloa, J., Lucatello, S., Cescutti, G., and Carretta, E.
- Subjects
Astrophysics - Astrophysics of Galaxies ,Astrophysics - Solar and Stellar Astrophysics - Abstract
Context. Globular clusters are considered key objects for understanding the formation and evolution of the Milky Way. In this sense, their characterisation in terms of their chemical and orbital parameters can provide constraints to the chemical evolution models of the Galaxy. Aims. We use the heavy element abundances of globular clusters to trace their overall behaviour in the Galaxy, aiming to analyse potential relations between the hot H-burning and s-process elements. Methods. We measured the content of Cu I and s- and r-process elements (Y II, Ba II, La II, and Eu II) in a sample of 210 giant stars in 18 Galactic Globular Clusters from high-quality UVES spectra. The clusters span a large metallicity range, and the sample is the largest uniformly analysed for what concerns heavy elements in Globular Clusters. Results. Cu abundances did not show considerable spread in the sample nor correlation with Na, meaning that the Na nucleosynthesis process does not affect the Cu abundance. Most GCs closely follow the Cu, Y, Ba, La, and Eu field stars' distribution, revealing a similar chemical evolution. The Y abundances in mid-metallicity regime GCs (-1.10 dex <[Fe/H]<-1.80 dex) display a mildly significant correlation with the Na abundance, which should be further investigated. Finally, we did not find any significant difference between the n-capture abundances among GCs with Galactic and extragalactic origin., Comment: 23pages and 20 figures
- Published
- 2024
43. Growth interruption strategies for interface optimization in GaAsSb/GaAsN type-II superlattices
- Author
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Braza, V., Ben, T., Flores, S., Reyes, D. F., Gallego-Carro, A., Stanojevic, L., Gacevic, Z., Ruíz-Marín, N., Ulloa, J. M., and González, D.
- Subjects
Condensed Matter - Materials Science - Abstract
Recently, GaAsSb/GaAsN type II short-period superlattices (SLs) have been proposed as suitable structures to be implemented in the optimal design of monolithic multi-junction solar cells. However, due to strong surface Sb segregation, experimental Sb composition profiles differ greatly from the nominal square-wave design. In this work, the improvement of the interface quality of these SLs in terms of compositional abruptness and surface roughness has been evaluated by implementing different growth interruption times under Sb4/As4 (soaking) and As4 (desorption) overpressure conditions before and after the growth of GaAsSb layers, respectively. The combined effects of both processes enhance Sb distribution, achieving squarer compositional profiles with reduced surface roughness interfaces. It has been found that the improvement in compositional abruptness is quantitatively much higher at the lower interface, during soaking, than at the upper interface during desorption. Conversely, a larger decrease in surface roughness is achieved at the upper interface than at the lower interface. Fitting of the Sb segregation profiles using the 3-layer kinetic fluid model has shown that the increase in Sb incorporation rate is due to the decrease in segregation energy, presumably to changes in the surface reconstruction of the floating layer at the surface., Comment: 7 pages, 5 figures
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- 2024
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44. Neurogenic Pulmonary Edema Associated with Hyponatremia, Primary Polydipsia, and Cannabis Use: A Case Report
- Author
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Treat, Christian, Ulloa, Nicholas, Kettler, Alyssa, and Lawrence, David
- Subjects
Neurogenic pulmonary edema ,hyponatremia ,primary polydipsia ,cannabis intoxication ,case report - Abstract
Introduction: Neurogenic pulmonary edema is a rare and potentially life-threatening condition that can present as severe pulmonary edema after significant neurologic insults. This is the first documented instance that shows a plausible causal link between cannabis consumption, psychogenic polydipsia, and the subsequent development of neurogenic pulmonary edema associated with status epilepticus secondary to acute hyponatremia.Case Report: We report a case of a 34-year-old female who presented to the emergency department altered and postictal after a witnessed new-onset seizure. She developed significant respiratory distress that required intubation. Her sodium was 121 millimoles per liter (mmol/L), from 137 mmol/L 36 hours prior on routine outpatient labs. Further history revealed excessive water ingestion after eating a cannabis edible prior to the seizure.Conclusion: This case highlights the importance of recognizing neurogenic pulmonary edema in connection with psychogenic polydipsia, severe hyponatremia, and status epilepticus subsequent to cannabis consumption.
- Published
- 2024
45. Knowledge, Attitudes, and Perceived Ethics Regarding the Use of ChatGPT among Generation Z University Students
- Author
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Benicio Gonzalo Acosta-Enriquez, Marco Agustín Arbulú Ballesteros, Carmen Graciela Arbulu Perez Vargas, Milca Naara Orellana Ulloa, Cristian Raymound Gutiérrez Ulloa, Johanna Micaela Pizarro Romero, Néstor Daniel Gutiérrez Jaramillo, Héctor Ulises Cuenca Orellana, Diego Xavier Ayala Anzoátegui, and Carlos López Roca
- Abstract
Artificial intelligence (AI) has been integrated into higher education (HE), offering numerous benefits and transforming teaching and learning. Since its launch, ChatGPT has become the most popular learning model among Generation Z college students in HE. This study aimed to assess the knowledge, concerns, attitudes, and ethics of using ChatGPT among Generation Z college students in HE in Peru. An online survey was administered to 201 HE students with prior experience using the ChatGPT for academic activities. Two of the six proposed hypotheses were confirmed: Perceived Ethics (B = 0.856) and Student Concerns (B = 0.802). The findings suggest that HE students' knowledge and positive attitudes toward ChatGPT do not guarantee its effective adoption and use. It is important to investigate how attitudes of optimism, skepticism, or apathy toward AI develop and how these attitudes influence the intention to use technologies such as the ChatGPT in HE settings. The dependence on ChatGPT raises ethical concerns that must be addressed with responsible use programs in HE. No sex or age differences were found in the relationship between the use of ChatGPTs and perceived ethics among HE students. However, further studies with diverse HE samples are needed to determine this relationship. To promote the ethical use of the ChatGPT in HE, institutions must develop comprehensive training programs, guidelines, and policies that address issues such as academic integrity, privacy, and misinformation. These initiatives should aim to educate students and university teachers on the responsible use of ChatGPT and other AI-based tools, fostering a culture of ethical adoption of AI to leverage its benefits and mitigate its potential risks, such as a lack of academic integrity.
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- 2024
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46. Forestalling Bullying in Primary and Secondary Schools in Spain
- Author
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Saneleuterio, Elia, López-García-Torres, Rocío, and Fernández-Ulloa, Teresa
- Abstract
Bullying refers to degrading actions, recurring and prolonged, exerted by minors on an equal. Physical or virtual assaults and insults, rejections or intimidations that hinder the victims' school activity and cause them to feel continually threatened are examples of bullying and cyberbullying, which have serious repercussions, not only on the emotional well-being and academic performance, but also on physical and mental health. It is necessary to build a citizenship engaged to education (Global Citizenship Education) to prevent bullying, and to work in other Sustainable Development Goals (SDGs). The solutions must involve families and teachers, particularly in the context of regulated education, where participation can be promoted in a more planned and controlled way. Expert approaches insist on the relevance of the school to prevent aggression and discrimination through critical and reflective attitudes towards the violence that surrounds these situations. It is about teaching students to reject them "ab initio" as inappropriate. The aim of this paper is to identify the characteristics of the interventions aimed at the prevention and detection of physical and psychological violence among school children in various settings and populations, specifically in Spain, as well as their results and controversial aspects. [Note: The page range (9-26) shown on the PDF is incorrect. The correct page range is 9-25.]
- Published
- 2023
47. Learning Outcomes and Training Satisfaction: A Case Study of Blended Customization in Professional Training
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Torre, Sara, Ulloa Severino, Antonio, and Ligorio, Maria Beatrice
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- 2024
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48. Effects of PreOperative radiotherapy in a preclinical glioblastoma model: a paradigm-shift approach
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Fernandez-Gil, Beatriz I., Schiapparelli, Paula, Navarro-Garcia de Llano, Juan P., Otamendi-Lopez, Andrea, Ulloa-Navas, Maria Jose, Michaelides, Loizos, Vazquez-Ramos, Carla A., Herchko, Steven M., Murray, Melissa E., Cherukuri, Yesesri, Asmann, Yan W., Trifiletti, Daniel M., and Quiñones-Hinojosa, Alfredo
- Published
- 2024
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49. Evaluation of different operational conditions in a microbial electrolysis cell inoculated with a pure culture of Shewanella oneidensis for hydrogen production
- Author
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Mendoza-Chávez, Claudia Erika, Mostafazadeh, Ali Khosravanipour, Drogui, Patrick, Buelna-Acedo, Gerardo, Ulloa-Mercado, Ruth Gabriela, Leyva-Soto, Luis Alonso, Serrano-Palacios, Denisse, Rentería-Méxia, Ana, Díaz-Tenorio, Lourdes Mariana, and Gortáres-Moryoqui, Pablo
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- 2024
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50. Identification of Single-Nucleotide Polymorphisms in Differentially Expressed Genes Favoring Soybean Meal Tolerance in Higher-Growth Zebrafish (Danio rerio)
- Author
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Ulloa, Pilar E., Jilberto, Felipe, Lam, Natalia, Rincón, Gonzalo, Valenzuela, Luis, Cordova-Alarcón, Valentina, Hernández, Adrián J., Dantagnan, Patricio, Ravanal, Maria Cristina, Elgueta, Sebastian, and Araneda, Cristian
- Published
- 2024
- Full Text
- View/download PDF
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