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1,353 results on '"L. Ramírez"'

1. Ocean alkalinity enhancement using sodium carbonate salts does not lead to measurable changes in Fe dynamics in a mesocosm experiment

Author

D. González-Santana, M. Segovia, M. González-Dávila, L. Ramírez, A. G. González, L. J. Pozzo-Pirotta, V. Arnone, V. Vázquez, U. Riebesell, and J. M. Santana-Casiano

Subjects
Ecology, QH540-549.5, Life, QH501-531, Geology, QE1-996.5
Abstract

The addition of carbonate minerals to seawater through an artificial ocean alkalinity enhancement (OAE) process increases the concentrations of hydroxide, bicarbonate, and carbonate ions. This leads to changes in the pH and the buffering capacity of the seawater. Consequently, OAE could have relevant effects on marine organisms and in the speciation and concentration of trace metals that are essential for their physiology. During September and October 2021, a mesocosm experiment was carried out in the coastal waters of Gran Canaria (Spain), consisting on the controlled variation of total alkalinity (TA). Different concentrations of carbonate salts (NaHCO3 and Na2CO3) previously homogenized were added to each mesocosm to achieve an alkalinity gradient between Δ0 to Δ2400 µmol L−1. The lowest point of the gradient was 2400 µmol kg−1, being the natural alkalinity of the medium, and the highest point was 4800 µmol kg−1. Iron (Fe) speciation was monitored during this experiment to analyse total dissolved iron (TdFe, unfiltered samples), dissolved iron (dFe, filtered through a 0.2 µm pore size filter), soluble iron (sFe, filtered through a 0.02 µm pore size filter), dissolved labile iron (dFe′), iron-binding ligands (LFe), and their conditional stability constants (KFeL′) because of change due to OAE and the experimental conditions in each mesocosm. Observed iron concentrations were within the expected range for coastal waters, with no significant increases due to OAE. However, there were variations in Fe size fractionation during the experiment. This could potentially be due to chemical changes caused by OAE, but such an effect is masked by the stronger biological interactions. In terms of size fractionation, sFe was below 1.0 nmol L−1, dFe concentrations were within 0.5–4.0 nmol L−1, and TdFe was within 1.5–7.5 nmol L−1. Our results show that over 99 % of Fe was complexed, mainly by L1 and L2 ligands with kFe′L′ ranging between 10.92 ± 0.11 and 12.68 ± 0.32, with LFe ranging from 1.51 ± 0.18 to 12.3 ± 1.8 nmol L−1. Our data on iron size fractionation, concentration, and iron-binding ligands substantiate that the introduction of sodium salts in this mesocosm experiment did not modify iron dynamics. As a consequence, phytoplankton remained unaffected by alterations in this crucial element.

Published
2024
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2. Intergovernmental relations in the management of the COVID-19 pandemic: X-ray of habitat management in a federal setting (Greater Buenos Aires Agglomeration, Argentina)

Author

M. M. Di Virgilio, M. P. Diaz, and L. Ramírez

Subjects
intergovernmental relations, pandemic, covid-19, habitat management, buenos aires, International relations, JZ2-6530
Abstract

In Argentina, during the year 2020, the National Government has implemented numerous and varied assistance, containment and promotion initiatives in key public policy sectors to respond to the crisis unleashed by the COVID-19 pandemic. Likewise, provincial and local governments launched their own initiatives to support those emanating from the central level and facilitate the implementation and adaptation of national initiatives in their territories. The citizens, for their part, have adapted to, used or resisted the guidelines and proposals of the executives of the different levels of government. The pandemic scenario (in its different phases) exposes the tension between a centralized logic - typical of the design of initiatives aimed at responding to an emergency - and multilevel governance at a time when it is impossible to ignored that crisis contexts, such as the one imposed by the COVID-19 pandemic, strongly stress the relations between the different levels of government and between these and the citizenry. In this context, this paper focuses on intergovernmental relations and examines the initiatives, devices and instruments mobilized by the different levels of government to respond to urban issues in general and housing needs in particular, in the pandemic context, focusing on the initiatives that had habitat and housing as a privileged axis of intervention. The work is based on the analysis of regulations and press material. It also draws on in-depth interviews with public officials and agents from different governmental levels. It presents the composition of the political organization of the Greater Buenos Aires Agglomerate and the political-institutional relations between thedifferent levels of government, as well as a characterization of the focal points for intervention, devices and instruments that made public interventions feasible (especially in the National Government, the Government of the City of Buenos Aires and the Government of the Province of Buenos Aires). To conclude, the paper focuses on territorially-based experiences in order to account for the initiatives from a bottom-up perspective.

Published
2022
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3. DIGITAL ENERGY SIMULATION OF BUILDINGS PROTECTED BY MUNICIPAL HERITAGE POLICIES IN THE FRAMEWORK OF ENERGY RENOVATION PROJECTS

Author

B. Serrano Lanzarote, P. Carnero Melero, V. Valero Escribano, and L. Ramírez Pareja

Subjects
Technology, Engineering (General). Civil engineering (General), TA1-2040, Applied optics. Photonics, TA1501-1820
Abstract

The energy simulation is a key tool when designing renovation actions on buildings. In the framework of the InterregMed SHERPA project, bound to trigger and manage energy renovations in public buildings, the digital analysis of an educational building affected by the municipal heritage protection has been carried out. The building is the CIPFP Blasco Ibáñez, catalogued as a monument of local interest in Valencia (Spain) city planning, where the heritage value of its facades (main and interior), roof and internal spatial structure is identified.The methodology used consists in performing an energy audit of the building in order to be able to customize a digital energy model. By means of an hourly dynamic energy simulation tool, the current status of the building and its systems can be determined, and energy renovation actions can be outlined. The use of digital analysis tools is of utmost interest in buildings declared as municipal heritage sites since enables the study to be performed in a non-intrusive manner. Several points of energy improvement are identified. There are some actions that can be performed without affecting parameters protected by the heritage status, and some others which need to be modified in order to be compliant with it. Furthermore, the digital analysis through energy simulation tools also allows to perform detailed calculations about the energy, environmental and economic savings associated with the measures. The assessment has proved the need to promote research and testing of new solutions and technologies to improve the energy efficiency of heritage buildings.

Published
2020
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4. Review: Strategies for enteric methane mitigation in cattle fed tropical forages

Author

J.C. Ku-Vera, O.A. Castelán-Ortega, F.A. Galindo-Maldonado, J. Arango, N. Chirinda, R. Jiménez-Ocampo, S.S. Valencia-Salazar, E.J. Flores-Santiago, M.D. Montoya-Flores, I.C. Molina-Botero, A.T. Piñeiro-Vázquez, J.I. Arceo-Castillo, C.F. Aguilar-Pérez, L. Ramírez-Avilés, and F.J. Solorio-Sánchez

Subjects
tropical grasses, legumes, cattle, rumen fermentation, greenhouse gases, Animal culture, SF1-1100
Abstract

Methane (CH4) is a greenhouse gas (GHG) produced and released by eructation to the atmosphere in large volumes by ruminants. Enteric CH4 contributes significantly to global GHG emissions arising from animal agriculture. It has been contended that tropical grasses produce higher emissions of enteric CH4 than temperate grasses, when they are fed to ruminants. A number of experiments have been performed in respiration chambers and head-boxes to assess the enteric CH4 mitigation potential of foliage and pods of tropical plants, as well as nitrates (NO3−) and vegetable oils in practical rations for cattle. On the basis of individual determinations of enteric CH4 carried out in respiration chambers, the average CH4 yield for cattle fed low-quality tropical grasses (>70% ration DM) was 17.0 g CH4/kg DM intake. Results showed that when foliage and ground pods of tropical trees and shrubs were incorporated in cattle rations, methane yield (g CH4/kg DM intake) was decreased by 10% to 25%, depending on plant species and level of intake of the ration. Incorporation of nitrates and vegetable oils in the ration decreased enteric CH4 yield by ∼6% to ∼20%, respectively. Condensed tannins, saponins and starch contained in foliages, pods and seeds of tropical trees and shrubs, as well as nitrates and vegetable oils, can be fed to cattle to mitigate enteric CH4 emissions under smallholder conditions. Strategies for enteric CH4 mitigation in cattle grazing low-quality tropical forages can effectively increase productivity while decreasing enteric CH4 emissions in absolute terms and per unit of product (e.g. meat, milk), thus reducing the contribution of ruminants to GHG emissions and therefore to climate change.

Published
2020
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5. Intussusception secondary to Meckel's diverticulum in a 3-month-old girl. Case report

Author

I. Camacho-Guerrero and L. Ramírez-Patiño

Subjects
Medicine (General), R5-920
Abstract

A 3-month-old female patient is presented, with ileo-ileal intussusception secondary to Meckel's diverticulum. The patient underwent emergency surgery due to a diagnosis of intestinal obstruction secondary to intussusception. Resumen: Se reporta caso de paciente femenino de 3 meses de edad, con una intususcepción intestinal íleo-ileal secundario a divertículo de Meckel, intervenida quirúrgicamente de urgencia por diagnóstico de obstrucción intestinal secundario a una invaginación intestinal. Keywords: Intussusception, Meckel's diverticulum, Palabras clave: Intususcepción intestinal, Divertículo Meckel

Published
2018
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6. Sistema para el Seguimiento del funcionamiento de ecosistemas en la Red de Parques Nacionales de España mediante Teledetección

Author

J. Cabello, D. Alcaraz-Segura, A. Reyes, P. Lourenço, J. M. Requena, J. Bonache, P. Castillo, S. Valencia, J. Naya, L. Ramírez, and J. Serrada

Subjects
anomalías, atributos funcionales, condiciones de referencia, estado de conservación, ganancias de carbono, índices espectrales de vegetación, Geography (General), G1-922
Abstract

La gestión de las áreas protegidas en el actual contexto de cambio global requiere de aproximaciones que permitan caracterizar y seguir el funcionamiento de los ecosistemas. La teledetección ofrece herramientas para ello, ya que proporciona índices que informan reiteradamente y para grandes porciones de territorio, de los intercambios de materia y energía que tienen lugar entre la biota y la superficie terrestre. Considerando este principio, y la cada vez mayor disponibilidad de información satelital de calidad y facilidad de uso, desarrollamos junto con el Organismo Autónomo de Parques Nacionales de España (OAPN), un sistema de seguimiento que complementa a otras iniciativas desarrolladas por este organismo para informar del estado de conservación de los parques nacionales. El sistema, denominado REMOTE, se basa en el empleo de los índices de vegetación espectrales (IVs) de uso más extendido (EVI -índice de vegetación mejorado- y NDVI -índice de vegetación normalizado-), derivados de la serie temporal de imágenes satelitales del sensor MODIS-Terra. El sistema permite avanzar en la identificación de las condiciones de referencia para la comprensión y predicción de las respuestas de los ecosistemas frente a perturbaciones e intervenciones, y de los cambios direccionales que éstos están experimentando (tendencias). Así mismo ayuda a la detección de anomalías recientes que alertan de cambios bruscos en el funcionamiento de los ecosistemas. REMOTE se caracteriza porque usa como indicadores tres atributos relacionados con las ganancias de carbono anuales (productividad primaria neta) por parte del dosel vegetal, su estacionalidad y fenología. Además, está diseñado y programado con software libre y gratuito, lo que permitirá modificar o implementar mejoras en él fácilmente. Su implementación tiene como objetivo informar a los tomadores de decisiones y gestores de la Red de Parques Nacionales de España de la salud y estado de conservación de los ecosistemas.

Published
2016
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7. Borsuk and V\'azsonyi problems through Reuleaux polyhedra

Author

Lopez-Campos, Gyivan, Oliveros, Deborah, and Alfonsín, Jorge L. Ramírez

Subjects
Mathematics - Combinatorics, Mathematics - Metric Geometry
Abstract

The Borsuk conjecture and the V\'azsonyi problem are two attractive and famous questions in discrete and combinatorial geometry, both based on the notion of diameter of a bounded sets. In this paper, we present an equivalence between the critical sets with Borsuk number 4 in $\mathbb{R}^3$ and the minimal structures for the V\'azsonyi problem by using the well-known Reuleaux polyhedra. The latter lead to a full characterization of all finite sets in $\mathbb{R}^3$ with Borsuk number 4. The proof of such equivalence needs various ingredients, in particular, we proved a conjecture dealing with strongly critical configuration for the V\'azsonyi problem and showed that the diameter graph arising from involutive polyhedra is vertex (and edge) 4-critical.

Published
2023

8. Coronal Heating as Determined by the Solar Flare Frequency Distribution Obtained by Aggregating Case Studies

Author

Mason, James Paul, Werth, Alexandra, West, Colin G., Youngblood, Allison A., Woodraska, Donald L., Peck, Courtney, Lacjak, Kevin, Frick, Florian G., Gabir, Moutamen, Alsinan, Reema A., Jacobsen, Thomas, Alrubaie, Mohammad, Chizmar, Kayla M., Lau, Benjamin P., Dominguez, Lizbeth Montoya, Price, David, Butler, Dylan R., Biron, Connor J., Feoktistov, Nikita, Dewey, Kai, Loomis, N. E., Bodzianowski, Michal, Kuybus, Connor, Dietrick, Henry, Wolfe, Aubrey M., Guerrero, Matt, Vinson, Jessica, Starbuck, Peter, Litton, Shelby D, Beck, M. G., Fisch, Jean-Paul, West, Ayana, Muniz, Alexis A., Chavez, Luis, Upthegrove, Zachary T., Runyon, Brenton M., Salazar, J., Kritzberg, Jake E., Murrel, Tyler, Ho, Ella, LaFemina, Quintin Y., Elbashir, Sara I., Chang, Ethan C., Hudson, Zachary A., Nussbaum, Rosemary O., Kennedy, Kellen, Kim, Kevin, Arango, Camila Villamil, Albakr, Mohammed A., Rotter, Michael, Garscadden, A. J., Salcido-Alcontar JR, Antonio, Pearl, Harrison M., Stepaniak, Tyler, Marquez, Josie A., Marsh, Lauren, Andringa, Jesse C, Osogwin, Austin, Shields, Amanda M., Brookins, Sarah, Hach, Grace K., Clausi, Alexis R., Millican, Emily B., Jaimes, Alan A, Graham, Alaina S., Burritt, John J., Perez, J. S., Ramirez, Nathaniel, Suri, Rohan, Myer, Michael S., Kresek, Zoe M., Goldsberry, C. A., Payne, Genevieve K., Jourabchi, Tara, Hu, J., Lucca, Jeffrey, Feng, Zitian, Gilpatrick, Connor B., Khan, Ibraheem A., Warble, Keenan, Sweeney, Joshua D., Dorricott, Philip, Meyer, Ethan, Kothamdi, Yash S., Sohail, Arman S., Grell, Kristyn, Floyd, Aidan, Bard, Titus, Mathieson, Randi M., Reed, Joseph, Cisneros, Alexis, Payne, Matthew P., Jarriel, J. R., Mora, Jacqueline Rodriguez, Sundell, M. E., Patel, Kajal, Alesmail, Mohammad, Alnasrallah, Yousef A, Abdullah, Jumana T., Molina-Saenz, Luis, Tayman, K. E., Brown, Gabriel T., Kerr-Layton, Liana, Berriman-Rozen, Zachary D., Hiatt, Quinn, Kalra, Etash, Ong, Jason, Vadayar, Shreenija, Shannahan, Callie D., Benke, Evan, zhang, Jinhua, Geisman, Jane, Martyr, Cara, Ameijenda, Federico, Akruwala, Ushmi H., Nehring, Molly, Kissner, Natalie, Rule, Ian C., Learned, Tyler, Smith, Alexandra N., Mazzotta, Liam, Rounsefell, Tyndall, Eyeson, Elizabeth A., Shelby, Arlee K., Moll, Tyler S, Menke, Riley, Shahba, Hannan, House Jr., Tony A., Clark, David B., Burns, Annemarie C., de La Beaujardiere, Tristan, Trautwein, Emily D., Plantz, Will, Reeves, Justin, Faber, Ian, Buxton, B. W., Highhouse, Nigel, Landrey, Kalin, Hansen, Connor M, Chen, Kevin, Hales, Ryder Buchanan, Borgerding, Luke R., Guo, Mutian, Crow, Christian J., Whittall, Lloyd C., Simmons, Conor, Folarin, Adeduni, Parkinson, Evan J., Rahn, Anna L., Blevins, Olivia, Morelock, Annalise M., Kelly, Nicholas, Parker, Nathan L., Smith, Kelly, Plzak, Audrey E., Saeb, David, Hares, Cameron T., Parker, Sasha R., McCoy, Andrew, Pham, Alexander V., Lauzon, Megan, Kennedy, Cayla J., Reyna, Andrea B., Acosta, Daniela M. Meza, Cool, Destiny J., Steinbarth, Sheen L., Mendoza-Anselmi, Patricia, Plutt, Kaitlyn E., Kipp, Isabel M, Rakhmonova, M., Brown, Cameron L., Van Anne, Gabreece, Moss, Alexander P., Golden, Olivia, Kirkpatrick, Hunter B., Colleran, Jake R., Sullivan, Brandon J, Tran, Kevin, Carpender, Michael Andrew, Mundy, Aria T., Koenig, Greta, Oudakker, Jessica, Engelhardt, Rasce, Ales, Nolan, Wexler, Ethan Benjamin, Beato, Quinn I, Chen, Lily, Cochran, Brooke, Hill, Paula, Hamilton, Sean R., Hashiro, Kyle, Khan, Usman, Martinez, Alexa M., Brockman, Jennifer L., Mallory, Macguire, Reed, Charlie, Terrile, Richard, Singh, Savi, Watson, James Adam, Creany, Joshua B., Price, Nicholas K., Miften, Aya M., Tran, Bryn, Kamenetskiy, Margaret, Martinez, Jose R., Opp, Elena N., Huang, Jianyang, Fails, Avery M., Belei, Brennan J., Slocum, Ryan, Astalos, Justin, East, Andrew, Nguyen, Lena P., Pherigo, Callie C, East, Andrew N., Li, David Y., Nelson, Maya LI, Taylor, Nicole, Odbayar, Anand, Rives, Anna Linnea, Mathur, Kabir P., Billingsley, Jacob, Polikoff, Hyden, Driscoll, Michael, Wilson, Orion K., Lahmers, Kyle, Toon, Nathaniel J., Lippincott, Sam, Musgrave, Andrew J., Gregory, Alannah H., Pitsuean-Meier, Sedique, Jesse, Trevor, Smith, Corey, Miles, Ethan J., Kainz, Sabrina J. H. T., Ji, Soo Yeun, Nguyen, Lena, Aryan, Maryam, Dinser, Alexis M., Shortman, Jadon, Bastias, Catalina S, Umbricht, Thomas D, Cage, Breonna, Randolph, Parker, Pollard, Matthew, Simone, Dylan M., Aramians, Andrew, Brecl, Ariana E., Robert, Amanda M., Zenner, Thomas, Saldi, Maxwell, Morales, Gavin, Mendez, Citlali, Syed, Konner, Vogel, Connor Maklain, Cone, Rebecca A., Berhanu, Naomi, Carpenter, Emily, Leoni, Cecilia, Bryan, Samuel, Ramachandra, Nidhi, Shaw, Timothy, Lee, E. C., Monyek, Eli, Wegner, Aidan B., Sharma, Shajesh, Lister, Barrett, White, Jamison R., Willard, John S., Sulaiman, S. A, Blandon, Guillermo, Narayan, Anoothi, Ruger, Ryan, Kelley, Morgan A., Moreno, Angel J., Balcer, Leo M, Ward-Chene, N. R. D., Shelby, Emma, Reagan, Brian D., Marsh, Toni, Sarkar, Sucheta, Kelley, Michael P., Fell, Kevin, Balaji, Sahana, Hildebrand, Annalise K., Shoha, Dominick, Nandu, Kshmya, Tucker, Julia, Cancio, Alejandro R., Wang, Jiawei, Rapaport, Sarah Grace, Maravi, Aimee S., Mayer, Victoria A., Miller, Andrew, Bence, Caden, Koke, Emily, Fauntleroy, John T, Doermer, Timothy, Al-Ghazwi, Adel, Morgan, Remy, Alahmed, Mohammed S., Mathavan, Adam Izz Khan Mohd Reduan, Silvester, H. K., Weiner, Amanda M., Liu, Nianzi, Iovan, Taro, Jensen, Alexander V., AlHarbi, Yazeed A., Jiang, Yufan, Zhang, Jiaqi, Jones, Olivia M., Huang, Chenqi, Reh, Eileen N., Alhamli, Dania, Pettine, Joshua, Zhou, Chongrui, Kriegman, Dylan, Yang, Jianing, Ash, Kevin, Savage, Carl, Kaiser, Emily, Augenstein, Dakota N., Padilla, Jacqueline, Stark, Ethan K., Hansen, Joshua A., Kokes, Thomas, Huynh, Leslie, Sanchez-Sanchez, Gustavo, Jeseritz, Luke A., Carillion, Emma L., Vepa, Aditya V., Khanal, Sapriya, Behr, Braden, Martin, Logan S., McMullan, Jesse J., Zhao, Tianwei, Williams, Abigail K., Alqabani, Emeen, Prinster, Gale H., Horne, Linda, Ruggles-Delgado, Kendall, Otto, Grant, Gomez, Angel R., Nguyen, Leonardo, Brumley, Preston J., Venegas, Nancy Ortiz, Varela, Ilian, Brownlow, Jordi, Cruz, Avril, Leiker, Linzhi, Batra, Jasleen, Hutabarat, Abigail P., Nunes-Valdes, Dario, Jameson, Connor, Naqi, Abdulaziz, Adams, Dante Q., Biediger, Blaine B., Borelli, William T, Cisne, Nicholas A., Collins, Nathaniel A., Curnow, Tyler L., Gopalakrishnan, Sean, Griffin, Nicholas F., Herrera, Emanuel, McGarvey, Meaghan V., Mellett, Sarah, Overchuk, Igor, Shaver, Nathan, Stratmeyer, Cooper N., Vess, Marcus T., Juels, Parker, Alyami, Saleh A., Gale, Skylar, Wallace, Steven P., Hunter, Samuel C, Lonergan, Mia C., Stewart, Trey, Maksimuk, Tiffany E., Lam, Antonia, Tressler, Judah, Napoletano, Elena R., Miller, Joshua B., Roy, Marc G., Chanders, Jasey, Fischer, Emmalee, Croteau, A. J., Kuiper, Nicolas A., Hoffman, Alex, DeBarros, Elyse, Curry, Riley T., Brzostowicz, A., Courtney, Jonas, Zhao, Tiannie, Szabo, Emi, Ghaith, Bandar Abu, Slyne, Colin, Beck, Lily, Quinonez, Oliver, Collins, Sarah, Madonna, Claire A., Morency, Cora, Palizzi, Mallory, Herwig, Tim, Beauprez, Jacob N., Ghiassi, Dorsa, Doran, Caroline R., Yang, Zhanchao, Padgette, Hannah M., Dicken, Cyrus A., Austin, Bryce W., Phalen, Ethan J., Xiao, Catherine, Palos, Adler, Gerhardstein, Phillip, Altenbern, Ava L., Orbidan, Dan, Dorr, Jackson A., Rivas, Guillermo A., Ewing, Calvin A, Giebner, B. C., McEntee, Kelleen, Kite, Emily R., Crocker, K. A., Haley, Mark S., Lezak, Adrienne R., McQuaid, Ella, Jeong, Jacob, Albaum, Jonathan, Hrudka, E. M., Mulcahy, Owen T., Tanguma, Nolan C., Oishi-Holder, Sean, White, Zachary, Coe, Ryan W., Boyer, Christine, Chapman, Mitchell G., Fortino, Elise, Salgado, Jose A., Hellweg, Tim, Martinez, Hazelia K., Mitchell, Alexander J., Schubert, Stephanie H., Schumacher, Grace K, Tesdahl, Corey D, Uphoff, C. H., Vassilyev, Alexandr, Witkoff, Briahn, Wolle, Jackson R., Dice, Kenzie A., Behrer, Timothy A., Bowen, Troy, Campbell, Andrew J, Clarkson, Peter C, Duong, Tien Q., Hawat, Elijah, Lopez, Christian, Olson, Nathaniel P., Osborn, Matthew, Peou, Munisettha E., Vaver, Nicholas J., Husted, Troy, Kallemeyn, Nicolas Ian, Spangler, Ava A, Mccurry, Kyle, Schultze, Courtney, Troisi, Thomas, Thomas, Daniel, Ort, Althea E., Singh, Maya A., Soon, Caitlin, Patton, Catherine, Billman, Jayce A., Jarvis, Sam, Hitt, Travis, Masri, Mirna, Albalushi, Yusef J., Schofer, Matthew J, Linnane, Katherine B., Knott, Philip Whiting, Valencia, Whitney, Arias-Robles, Brian A., Ryder, Diana, Simone, Anna, Abrams, Jonathan M., Belknap, Annelene L., Rouse, Charlotte, Reynolds, Alexander, Petric, Romeo S. L., Gomez, Angel A., Meiselman-Ashen, Jonah B., Carey, Luke, Dias, John S., Fischer-White, Jules, Forbes, Aidan E., Galarraga, Gabriela, Kennedy, Forrest, Lawlor, Rian, Murphy, Maxwell J., Norris, Cooper, Quarderer, Josh, Waller, Caroline, Weber, Robert J., Gunderson, Nicole, Boyne, Tom, Gregory, Joshua A., Propper, Henry Austin, von Peccoz, Charles B. Beck, Branch, Donovan, Clarke, Evelyn, Cutler, Libby, Dabberdt, Frederick M., Das, Swagatam, Figueirinhas, John Alfred D., Fougere, Benjamin L., Roy, Zoe A., Zhao, Noah Y., Cox, Corben L., Barnhart, Logan D. W., Craig, Wilmsen B., Moll, Hayden, Pohle, Kyle, Mueller, Alexander, Smith, Elena K., Spicer, Benjamin C., Aycock, Matthew C., Bat-Ulzii, Batchimeg, Murphy, Madalyn C., Altokhais, Abdullah, Thornally, Noah R., Kleinhaus, Olivia R., Sarfaraz, Darian, Barnes, Grant M., Beard, Sara, Banda, David J, Davis, Emma A. B., Huebsch, Tyler J., Wagoner, Michaela, Griego, Justus, Hale, Jack J. Mc, Porter, Trevor J., Abrashoff, Riley, Phan, Denise M., Smith, Samantha M., Srivastava, Ashish, Schlenker, Jared A. W., Madsen, Kasey O., Hirschmann, Anna E., Rankin, Frederick C, Akbar, Zainab A., Blouin, Ethan, Coleman-Plante, Aislinn, Hintsa, Evan, Lookhoff, Emily, Amer, Hamzi, Deng, Tianyue, Dvorak, Peter, Minimo, Josh, Plummer, William C., Ton, Kelly, Solt, Lincoln, AlAbbas, Batool H., AlAwadhi, Areej A., Cooper, Nicholas M., Corbitt, Jessica S, Dunlap, Christian, Johnson, Owen, Malone, Ryan A., Tellez, Yesica, Wallace, Logan, Ta, Michael-Tan D., Wheeler, Nicola H., Ramirez, Ariana C., Huang, Shancheng, Mehidic, Amar, Christiansen, Katherine E, Desai, Om, Domke, Emerson N., Howell, Noah H., Allsbrook, Martin, Alnaji, Teeb, England, Colin, Siles, Nathan, Burton, Nicholas David, Cruse, Zoe, Gilmartin, Dalton, Kim, Brian T., Hattendorf, Elsie, Buhamad, Maryam, Gayou, Lily, Seglem, Kasper, Alkhezzi, Tameem, Hicks, Imari R., Fife, Ryann, Pelster, Lily M., Fix, Alexander, Sur, Sohan N., Truong, Joshua K., Kubiak, Bartlomiej, Bondar, Matthew, Shi, Kyle Z., Johnston, Julia, Acevedo, Andres B., Lee, Junwon, Solorio, William J., Johnston, Braedon Y., McCormick, Tyler, Olguin, Nicholas, Pastor, Paige J., Wilson, Evan M., Trunko, Benjamin L., Sjoroos, Chris, Adams, Kalvyn N, Bell, Aislyn, Brumage-Heller, Grant, Canales, Braden P., Chiles, Bradyn, Driscoll, Kailer H., Hill, Hallie, Isert, Samuel A., Ketterer, Marilyn, Kim, Matthew M., Mewhirter, William J., Phillips, Lance, Phommatha, Krista, Quinn, Megan S., Reddy, Brooklyn J., Rippel, Matthew, Russell, Bowman, Williams, Sajan, Pixley, Andrew M., Gapin, Keala C., Peterson, B., Ruprecht, Collin, Hardie, Isabelle, Li, Isaac, Erickson, Abbey, Gersabeck, Clint, Gopalani, Mariam, Allanqawi, Nasser, Burton, Taylor, Cahn, Jackson R., Conti, Reese, White, Oliver S., Rojec, Stewart, Hogen, Blake A., Swartz, Jason R., Dick, R., Battist, Lexi, Dunn, Gabrielle M., Gasser, Rachel, Logan, Timothy W., Sinkovic, Madeline, Schaller, Marcus T., Heintz, Danielle A., Enrich, Andrew, Sanchez, Ethan S., Perez, Freddy, Flores, Fernando, Kapla, Shaun D., Shockley, Michael C., Phillips, Justin, Rumley, Madigan, Daboub, Johnston, Karsh, Brennan J., Linders, Bridget, Chen, Sam, Do, Helen C., Avula, Abhinav, French, James M., Bertuccio, Chrisanna, Hand, Tyler, Lee, Adrianna J., Neeland, Brenna K, Salazar, Violeta, Andrew, Carter, Barmore, Abby, Beatty, Thomas, Alonzi, Nicholas, Brown, Ryan, Chandler, Olivia M., Collier, Curran, Current, Hayden, Delasantos, Megan E., Bonilla, Alberto Espinosa de los Monteros, Fowler, Alexandra A., Geneser, Julianne R., Gentry, Eleanor, Gustavsson, E. R., Hansson, Jonathan, Hao, Tony Yunfei, Herrington, Robert N., Kelly, James, Kelly, Teagan, Kennedy, Abigail, Marquez, Mathew J., Meillon, Stella, Palmgren, Madeleine L., Pesce, Anneliese, Ranjan, Anurag, Robertson, Samuel M., Smith, Percy, Smith, Trevor J, Soby, Daniel A., Stratton, Grant L., Thielmann, Quinn N., Toups, Malena C., Veta, Jenna S., Young, Trenton J., Maly, Blake, Manzanares, Xander R., Beijer, Joshua, George, Jacob D., Mills, Dylan P., Ziebold, Josh J, Chambers, Paige, Montoya, Michael, Cheang, Nathan M., Anderson, Hunter J., Duncan, Sheridan J., Ehrlich, Lauren, Hudson, Nathan C., Kiechlin, Jack L., Koch, Will, Lee, Justin, Menassa, Dominic, Oakes, S. H., Petersen, Audrey J., Bunsow, J. R. Ramirez, Bay, Joshua, Ramirez, Sacha, Fenwick, Logan D., Boyle, Aidan P., Hibbard, Lea Pearl, Haubrich, Calder, Sherry, Daniel P., Jenkins, Josh, Furney, Sebastian, Velamala, Anjali A., Krueger, Davis J., Thompson, William N., Chhetri, Jenisha, Lee, Alexis Ying-Shan, Ray, Mia G. V., Recchia, John C., Lengerich, Dylan, Taulman, Kyle, Romero, Andres C., Steward, Ellie N., Russell, Sloan, Hardwick, Dillon F., Wootten, Katelynn, Nguyen, Valerie A., Quispe, Devon, Ragsdale, Cameron, Young, Isabel, Atchley-Rivers, N. S., Stribling, Jordin L., Gentile, Julia G, Boeyink, Taylor A., Kwiatkowski, Daniel, Dupeyron, Tomi Oshima, Crews, Anastasia, Shuttleworth, Mitchell, Dresdner, Danielle C., Flackett, Lydia, Haratsaris, Nicholas, Linger, Morgan I, Misener, Jay H., Patti, Samuel, Pine, Tawanchai P., Marikar, Nasreen, Matessi, Giorgio, Routledge, Allie C., Alkaabi, Suhail, Bartman, Jessica L., Bisacca, Gabrielle E., Busch, Celeste, Edwards, Bree, Staudenmier, Caitlyn, Starling, Travis, McVey, Caden, Montano, Maximus, Contizano, Charles J., Taylor, Eleanor, McIntyre, James K., Victory, Andrew, McCammon, Glen S., Kimlicko, Aspen, Sheldrake, Tucker, Shelchuk, Grace, Von Reich, Ferin J., Hicks, Andrew J., O'neill, Ian, Rossman, Beth, Taylor, Liam C., MacDonald, William, Becker, Simone E., Han, Soonhee, O'Sullivan, Cian, Wilcove, Isaac, Brennan, David J., Hanley, Luke C., Hull, Owen, Wilson, Timothy R., Kalmus, Madison H., Berv, Owen A., Harris, Logan Swous, Doan, Chris H, Londres, Nathan, Parulekar, Anish, Adam, Megan M., Angwin, Abigail, Cabbage, Carter C., Colleran, Zachary, Pietras, Alex, Seux, Octave, Oros, Ryan, Wilkinson, Blake C., Nguyen, Khoa D, Trank-Greene, Maedee, Barone, Kevin M., Snyder, G. L., Biehle, Samuel J, Billig, Brennen, Almquist, Justin Thomas, Dixon, Alyssa M., Erickson, Benjamin, Evans, Nathan, Genne, SL, Kelly, Christopher M, Marcus, Serafima M., Ogle, Caleb, Patel, Akhil, Vendetti, Evan, Courtney, Olivia, Deel, Sean, Del Foco, Leonardo, Gjini, Michael, Haines, Jessica, Hoff, Isabelle J., Jones, M. R., Killian, Dominic, Kuehl, Kirsten, Kuester, Chrisanne, Lantz, Maxwell B., Lee, Christian J, Mauer, Graham, McKemey, Finbar K., Millican, Sarah J., Rosasco, Ryan, Stewart, T. C., VanEtten, Eleanor, Derwin, Zachary, Serio, Lauren, Sickler, Molly G., Blake, Cassidy A., Patel, Neil S., Fox, Margaret, Gray, Michael J, Ziegler, Lucas J., Kumar, Aman Priyadarshi, Polly, Madelyn, Mesgina, Sarah, McMorris, Zane, Griffin, Kyle J., Haile, L. N., Bassel, Claire, Dixon, Thomas J., Beattie, Ryan, Houck, Timothy J, Rodgers, Maeve, Trofino, Tyson R., Lukianow, Dax, Smart, Korben, Hall, Jacqueline L., Bone, Lauren, Baldwin, James O., Doane, Connor, Almohsen, Yousef A., Stamos, Emily, Acha, Iker, Kim, Jake, Samour II, Antonio E., Chavali, S., Kanokthippayakun, Jeerakit, Gotlib, Nicholas, Murphy, Ryan C., Archibald, Jack. W., Brimhall, Alexander J, Boyer, Aidan, Chapman, Logan T., Chadda, Shivank, Sibrell, Lisa, Vallery, Mia M., Conroy, Thomas C., Pan, Luke J., Balajonda, Brian, Fuhrman, Bethany E. S., Alkubaisi, Mohamed, Engelstad, Jacob, Dodrill, Joshua, Fuchs, Calvin R., Bullard-Connor, Gigi, Alhuseini, Isehaq, Zygmunt, James C., Sipowicz, Leo, Hayrynen, Griffin A., McGill, Riley M., Keating, Caden J., Hart, Omer, Cyr, Aidan St., Steinsberger, Christopher H., Thoman, Gerig, Wood, Travis M., Ingram, Julia A., Dominguez, J., Georgiades, Nathaniel James, Johnson, Matthew, Johnson, Sawyer, Pedersen, Alexander J., Ralapanawe, Anoush K, Thomas, Jeffrey J., Sato, Ginn A., Reynolds, Hope, Nasser, Liebe, Mizzi, Alexander Z., Damgaard, Olivia, Baflah, Abdulrahman A., Liu, Steven Y., Salindeho, Adam D., Norden, Kelso, Gearhart, Emily E., Krajnak, Zack, Szeremeta, Philip, Amos, Meggan, Shin, Kyungeun, Muckenthaler, Brandon A., Medialdea, Melissa, Beach, Simone, Wilson, Connor B., Adams, Elena R, Aldhamen, Ahmed, Harris, Coyle M., Hesse, Troy M., Golding, Nathan T., Larter, Zachary, Hernandez, Angel, Morales, Genaro, Traxler, Robert B., Alosaimi, Meshal, Fitton, Aidan F., Aaron, James Holland, Lee, Nathaniel F., Liao, Ryan Z., Chen, Judy, French, Katherine V., Loring, Justin, Colter, Aurora, McConvey, Rowan, Colozzi, Michael, Vann, John D., Scheck, Benjamin T., Weigand, Anthony A, Alhabeeb, Abdulelah, Idoine, Yolande, Woodard, Aiden L., Medellin, Mateo M., Ratajczyk, Nicholas O, Tobin, Darien P., Collins, Jack C., Horning, Thomas M., Pellatz, Nick, Pitten, John, Lordi, Noah, Patterson, Alyx, Hoang, Thi D, Zimmermann, Ingrid H, Wang, Hongda, Steckhahn, Daniel, Aradhya, Arvind J., Oliver, Kristin A., Cai, Yijian, Wang, Chaoran, Yegovtsev, Nikolay, Wu, Mengyu, Ganesan, Koushik, Osborne, Andrew, Wickenden, Evan, Meyer, Josephine C., Chaparro, David, Visal, Aseem, Liu, Haixin, Menon, Thanmay S., Jin, Yan, Wilson, John, Erikson, James W., Luo, Zheng, Shitara, Nanako, Nelson, Emma E, Geerdts, T. R., Ortiz, Jorge L Ramirez, and Lewandowski, H. J.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

Flare frequency distributions represent a key approach to addressing one of the largest problems in solar and stellar physics: determining the mechanism that counter-intuitively heats coronae to temperatures that are orders of magnitude hotter than the corresponding photospheres. It is widely accepted that the magnetic field is responsible for the heating, but there are two competing mechanisms that could explain it: nanoflares or Alfv\'en waves. To date, neither can be directly observed. Nanoflares are, by definition, extremely small, but their aggregate energy release could represent a substantial heating mechanism, presuming they are sufficiently abundant. One way to test this presumption is via the flare frequency distribution, which describes how often flares of various energies occur. If the slope of the power law fitting the flare frequency distribution is above a critical threshold, $\alpha=2$ as established in prior literature, then there should be a sufficient abundance of nanoflares to explain coronal heating. We performed $>$600 case studies of solar flares, made possible by an unprecedented number of data analysts via three semesters of an undergraduate physics laboratory course. This allowed us to include two crucial, but nontrivial, analysis methods: pre-flare baseline subtraction and computation of the flare energy, which requires determining flare start and stop times. We aggregated the results of these analyses into a statistical study to determine that $\alpha = 1.63 \pm 0.03$. This is below the critical threshold, suggesting that Alfv\'en waves are an important driver of coronal heating., Comment: 1,002 authors, 14 pages, 4 figures, 3 tables, published by The Astrophysical Journal on 2023-05-09, volume 948, page 71

Published
2023
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9. Effect of single layer centrifugation using Androcoll-E-Large on the sperm quality parameters of cooled-stored donkey semen doses

Author

I. Ortiz, J. Dorado, L. Ramírez, J.M. Morrell, D. Acha, M. Urbano, M.J. Gálvez, J.J. Carrasco, V. Gómez-Arrones, R. Calero-Carretero, and M. Hidalgo

Subjects
single layer centrifugation, donkey semen, sperm cooling, Androcoll-E-Large, Animal culture, SF1-1100
Abstract

The aim of this study was to determine the effect of single layer centrifugation (SLC) using Androcoll-E-Large on donkey sperm quality parameters after 24 h of cool-storage. Ejaculates were collected from Andalusian donkeys and then cooled at 5°C. SLC was carried out after 24 h of cool-storage using Androcoll-E-Large. In the first experiment, all sperm parameters assessed (total and progressive sperm motility, viability, sperm morphology and sperm kinematics VCL, VSL, VAP, LIN, STR, WOB, ALH and BCF) were statistically compared between semen samples processed or not with Androcoll-E-Large. Significant differences (P

Published
2014
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10. Caracterización bioquímica de AmiJ33, una amilasa de Bacillus amyloliquefaciens aislada de suelos cultivados con caña de azúcar en la región del Papaloapan

Author

J. J. Montor-Antonio, C. Olvera-Carranza, D. Reyes-Duarte, B. Sachman-Ruiz, L. Ramírez-Coutiño, and S. Del Moral

Subjects
Science, Science (General), Q1-390, Social Sciences, Social sciences (General), H1-99
Abstract

La amilasa (E.C. 3.2.1.1) de Bacillus amyloliquefaciens JJC33M (AmiJ33) fue producida por fermentación sumergida. Se probó el efecto de peptona, extracto de levadura, Ca+2 y glicina en la producción de AmiJ33. El extracto de levadura y Ca+2 tuvieron un efecto positivo sobre la síntesis de AmiJ33. La enzima fue recuperada mediante precipitación a saturación al 60% con (NH4)2SO4. El peso molecular aproximado de la enzima purificada fue de 50 kDa. Así mismo, se evaluó el efecto del pH y la temperatura sobre la actividad enzimática, concluyendo que los valores más altos de actividad se observaron a pH 6.0 y 80°C, respectivamente. En condiciones ligeramente ácidas (pH 4.0 y 5.0), AmiJ33 mantuvo el 72% de su actividad. AmiJ33 fue estable por 3 h a 40°C, y por 30 min a 45 y 50°C, conservando el 88 y 82% de actividad residual. A 60°C, la actividad disminuyó 40%. La actividad de AmiJ33 se incrementó 50.27% con b- mercaptoetanol, no fue inhibida por EDTA y se inhibió totalmente con SDS.

Published
2014

11. Links in orthoplicial Apollonian packings

Author

Alfonsín, Jorge L. Ramírez and Rasskin, Iván

Subjects
Mathematics - Geometric Topology, Mathematics - Combinatorics, 52C26, 57K10, 11D72
Abstract

In this paper, we establish a connection between Apollonian packings and knot theory. We introduce new representations of links realized in the tangency graph of the regular crystallographic sphere packings. Particularly, we prove that any algebraic link can be realized in the cubic section of the orthoplicial Apollonian packing. We use these representations to improve the upper bound on the ball number of an infinite family of alternating algebraic links. Furthermore, the later allow us to reinterpret the correspondence of rational tangles and rational numbers and to reveal geometrically primitive solutions for the Diophantine equation $x^4 + y^4 + z^4 = 2t^2$., Comment: 18 pages, 25 figures. To be published in European Journal of Combinatorics

Published
2023

12. Prototype App Mobile for Real Time American Sign Language Recognition Based on Deep Learning

Author

Ramirez, Sergio A., L. Ramírez, María del Pilar, Tito, Euler, Apaza, Honorio, Kacprzyk, Janusz, Series Editor, Gomide, Fernando, Advisory Editor, Kaynak, Okyay, Advisory Editor, Liu, Derong, Advisory Editor, Pedrycz, Witold, Advisory Editor, Polycarpou, Marios M., Advisory Editor, Rudas, Imre J., Advisory Editor, Wang, Jun, Advisory Editor, and Arai, Kohei, editor

Published
2024
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13. Interacciones radiculares en sistemas agroforestales: mecanismos y opciones de manejo

Author

F. Casanova, L. Ramírez, and F. Solorio

Subjects
asociación arbórea, competencia, complementación, Agriculture (General), S1-972, Animal culture, SF1-1100
Abstract

Los sistemas agroforestales (SAF) son una forma de uso de la tierra en donde las leñosas interactúan con los cultivos y/o animales, con la finalidad de diversificar y optimizar la producción de manera sostenida. Sin embargo, estos sistemas tienen limitantes originados por una combinación inadecuada de las diferentes especies, lo que resulta en competencia entre ellas. Las características radiculares de las especies leñosas tienen un papel importante en el éxito de los SAF, ya que indican modificaciones que pudieran existir entre especies asociadas. Por tanto, el objetivo de esta revisión es analizar la importancia de las interacciones radiculares, los criterios para el manejo con base en las características morfológicas y patrones de crecimiento entre especies y su impacto en los SAF. La incorporación de especies arbóreas dentro de los cultivos requiere de objetivos claros; es decir, conocer el papel que desempeñarían dentro del sistema. No es redituable utilizar especies arbóreas que no poseen cierto valor o producto, ya que la competencia entre los árboles y los cultivos es solamente admisible si es compensada a través de porlas ventajas con relación a los aumentos en la productividad de sistema. Son deseables aquellas especies arbóreas cuyas raíces sean agresivas con relación a los sistemas radiculares del cultivo asociado, y que manifiesten un crecimiento lateral profundo y/o posean una alta plasticidad. Una opción para reducir la competencia radicular es la regulación del espaciamiento y/o distribución de las diversas especies asociadas, así como la aplicación de prácticas de manejo. Los patrones de la actividad radicular de las plantas difieren entre especies, su conocimiento puede ayudar a evitar competencia excesiva y pérdidas de nutrientes en SAF con la asignación óptima del espacio y recursos disponibles.

Published
2007

14. Resúmenes

Author

P. Abad, P. Abreu, N. Acencio, S. Acevedo, V. Acevedo, R. Agohn, L. Albornoz, P. Alvarez, C. Arana, A. Arango, J. J. Arango, A. Arbeláez, L. E. Arbeláez, W. Arboleda, A. Arenas, I. C. Arenas, M. L. Arias, A. Aristizábal, D. Aristizábal, E. Arrieta, M. Arrieta, H. Arroyave, J. A. Arroyo, F. Arteaga, G. Ascione, R. Asenjo, B. Astudillo, L. H. Atehortúa, A. Badel, M. Badiel, S. Balestrini, R. Barragán, C. Barrera, J. C. Barrera, J. G. Barrera, L. M. Benítez, M. J. Bermúdez, O. Bernal, J. Betancourt, G. Blanco, R. Bohórquez, D. Bravo, R. Bresciani, A. Builes, L Buitrago, A. Burgoa, L. P. Báez, J. Cabrales, M. Cabrales, C. Cabrera, A. M. Cadavid, E. Cadavid, R. Cadena, L. C. Caicedo, V. Caicedo, J. Calderón, L. I. Calderón, J. Camacho, P. Camacho, P. A. Camacho, D. M. Camargo, M. T. Campos, G. Campuzano, A. Capasso, H. Cardona, J. Cardona, A. Carreño, M. Carreño, G. Carrillo, G. Casariego, G. Cassalett, H. Castellanos, M. Castillo, V. Castillo, H. Castro, J. Castro, P. Castro, E. Cañas, A. Celis, L. A. Celis, A. Chávez, J. C. Chávez, A. Colorado, E. Contreras, A. Coral, M. Coronado, J. R. Correa, S. Corredor, L. Corzo, O. Corzo, J. M. Cotes, A. Cruz, C. Cubides, F. Cuellar, A. Cuervo, A. Cárdenas, M. Cárdenas, M. E. Cárdenas, P. E. Cárdenas, W. Cárdenas, C. De Viveros, A. Delgadillo, J. Delgado, P. Delgado, B. P. Donado, J. R. Donado, E. Duarte, R. Dueñas, J. G. Duque, M. Duque, L. Durango, A. E. Durán, M. A. Durán, L. M. Dávila, A. Díaz, A. L. Díaz, C. Díaz, G. Díaz, L. Díaz, L. A. Díaz, L. H. Díaz, M. Díaz, S. Díaz, V Díaz, J. Echavarría, D. Echeverri, M. Echeverri, L. Echeverría, R. Echeverría, J. Erdmenger, A. Escobar, C. Escobar, E. Escobar, E. Escorcia, A. Espinosa, R. Espíndola, G. Estrada, J. Estrada, A. M. Estupiñán, C. Eusse, A. Fernández, D. Fernández, H. Fernández, N. Fernández, O. Fernández, R. Fernández, M. Flórez, M. R. Fontanilla, C. A. Fragozo, C. Franco, G. Franco, H. J. Franco, J. Franco, S. Franco, J. Gallo, J. Garcés, E. García, L. García, M. E. Garzón, A. Gaviria, E. Gil, D. Giraldo, J. A. Giraldo, JC. Giraldo, N. Giraldo, O. F. Gomesese, G. González, M. González, R. González, M. Gordillo, R. Guanes, P. Guerra, L. Guerrero, L. Guitérrez, F. Gulh, J. Gutiérrez, M. Gutiérrez, G. Guyatt, L. Guzmán, N. Guzmán, J. Gárces, A. Gómez, C. A. Gómez, F. Gómez, G. Gómez, G. S. Gómez, J. Gómez, J. F. Gómez, M. Gómez, P. F. Gómez, A. Hernández, C. Hernández, E. Hernández, G. Hernández, H. Hernández, L. Hernández, N. Hernández, V. M. Herrera, A. Hoyos, E. F. Hurtado, P. Ibarra, D. Indaburu, A. Iragorri, D. Isaza, F. Jaimes, G. Jaimes, C. Jaramillo, C. J. Jaramillo, G. Jaramillo, J. Jaramillo, J. C. Jaramillo, J. S. Jaramillo, M. Jaramillo, M. H. Jaramillo, N. Jaramillo, R. Jaramillo, M. Jiménes, C. Jiménez, L. Jiménez, L. S. Jiménez, M. Jiménez, A. Jurado, A. F. Jurado, J. Lemus, R. Leyes, J. León, R. Lince, J. Lizarazo, F. Lizcano, A. Llamas, J. F. Llano, B. Lombo, M. Lozano, C. Luengas, L. H. Lugo, F. López, M. López, P. López, I. Malabet, J. Maldonado, E. J. Manrique, F. Manrique, G. Mantilla, E. Manzi, H. Martínez, J. P. Martínez, L. X. Martínez, M. P. Martínez, J. Marín, L. Mateus, N. Matías, A. Mayorga, A. Medina, E. Medina, H. Medina, Mejía, A. Mejía, D. Mejía, I. Mejía, S. Mendoza, A. Merchán, S. Merlano, A. Miranda, C. Molina, J. Montenegro, A. Montero, G. Montero, G. A. Montero, F. Montes, E. Montoya, J. D. Montoya, L. M. Montoya, M. Montoya, E. Moreno, C. Morillo, C. A. Morillo, R. Morris, W. Mosquera, L. Moya, R. Murgueitio, A. Muñoz, J. A. Mármol, A. Márquez, A. Múnera, C. Nader, C. M. Navas, J. J. Navia, A. Negrete, M. E. Niño, C. A. Náder, F. Núñez, J. Ochoa, C. Olaya, L. Olaya, A. Orjuela, H. Orjuela, J. L. Orozco, C. M. Orrego, C. Ortiz, S. D. Ortiz, E. Osorio, C. A. Ospina, M. Oviedo, R. Oñate, L. M. Pabón, G. Palomino, C. Pardo, R. Pardo, G. A. Parra, J. C. Parra, L. E. Parra, T. Parra, M. Patarroyo, L. F. Pava, J. E. Pedraza, O. Pedraza, A. M. Peláz, A. Perafán, P. Perafán, S. Perafán, C. Petro, M. Pineda, J. B. Pinzón, P. S. Pira, C. Pizarro, D. Piñeros, R. Plata, P. Portilla, E. Prada, G. Pradilla, L. G. Pulgarín, G. Páez, L. Páez, C. Pérez, G. E. Pérez, J. Pérez, M. Pérez, K. Quesada, A. Quintero, D. Quintero, M. Quintero, C. Quiroz, M. L. Ramos, A. Ramírez, I. Ramírez, L. Ramírez, M. Ramírez, O. Ramírez, S. Ramírez, G. W. Rangel, J. C. Rendón, A. Restrepo, G. Restrepo, J. A. Restrepo, J. Reynolds, J. D. Rincón, O. S. Rincón, P. Rincón, G. Rivas, L. F. Rivas, F. Riveros, J. L. Roa, N. Roa, A. Rodríguez, D. C. Rodríguez, E. Rodríguez, J. Rodríguez, C. E. Rojas, J. C. Rojas, M. F. Romero, F. Rosas, J. F. Rosas, F. Rosso, C. L. Rueda, M. Rueda, C. F. Rueda-Clausen, A. Ruiz, D. Ruiz, E. J. Ruiz, H. Ruiz, M. Ruiz, M. Ruz, J. F. Saaibi, L. C. Saaibi, C. Salazar, D. Salazar, G. Salazar, C. Saldarriaga, N. Saldoval, C. L. Sanabria, A. G. Sandoval, J. M. Sandoval, N. Sandoval, N. F. Sandoval, H. Santos, J. M. Sarmiento, C. Satizábal, J. M. Senior, D. Serano, N. C. Serrano, F. Silva, F. A. Silva, S. Y. Silva, M. Smieja, E. Solano, J. A. Solano, M. Suárez, L. Sáenz, J. Tello, C. Tenorio, L. F. Tenorio, L. Thabane, C. Tique, N. Toro, A. Torres, G. Torres, P. Torres, Y. Torres, P. Trujillo, M. R. Téllez, J. Umaña, C. E. Uribe, F. Uribe, W. Uribe, M. T. Urrego, M. Vacca, M. Vallejo, D. Vanegas, D. I. Vanegas, E. Vanegas, C. Vargas, R. D. Vargas, J. A. Vega, H. M. Velasco, V. M. Velasco, D. Velásquez, J. Velásquez, J. G. Velásquez, M. Velásquez, O. Velásquez, B. E. Vesga, B.E. Vesga, C. Vidal, L. A. Villa, V. Villa, C. Villa-Roel, J. C. Villalba, C. Villalobos, C. Villamil, C. Villamizar, E. Villamizar, J. C. Villar, A. Villegas, F. Villegas, F. A. Villegas, M. F. Villegas, C. Vázquez, J. F. Vélez, L. A. Vélez, S. Vélez, M. Yabur, J. Zapara, H. Zapata, J. Zapata, J. G. Zarruk, A. Zuluaga, and O. Zuluaga

Subjects
Diseases of the circulatory (Cardiovascular) system, RC666-701
Published
2006

18. A polytopal generalization of Apollonian packings and Descartes' theorem

Author

Alfonsín, Jorge L. Ramírez and Rasskin, Iván

Subjects
Mathematics - Combinatorics, 51M20, 52C26, 05B40
Abstract

We present a generalization of Descartes' theorem for the family of polytopal sphere packings arising from uniform polytopes. The corresponding quadratic equation is expressed in terms of geometric invariants of uniform polytopes which are closely connected to canonical realizations of edge-scribable polytopes. We use our generalization to construct integral Apollonian packings based on the Platonic solids. Additionally, we also introduce and discuss a new spectral invariant for edge-scribable polytopes.

Published
2021

19. Self-dual maps II: links and symmetry

Author

Montejano, Luis, Alfonsín, Jorge L. Ramírez, and Rasskin, Ivan

Subjects
Mathematics - Geometric Topology, Mathematics - Combinatorics
Abstract

In this paper, we investigate representations of links that are either centrally symmetric in $\mathbb{R}^3$ or antipodally symmetric in $\mathbb{S}^3$. By using the notions of antipodally self-dual and antipodally symmetric maps, introduced and studied by the authors, we are able to present sufficient combinatorial conditions for a link $L$ to admit such representations. The latter naturally arises sufficient conditions for $L$ to be amphichiral. We also introduce another (closely related) method yielding again to sufficient conditions for $L$ to be amphichiral. We finally prove that a link $L$, associated to a map $G$, is amphichiral if the self-dual pairing of $G$ is not one of 6 specific ones among the classification of the 24 self-dual pairing $Cor(G) \rhd Aut(G)$., Comment: 36 pages

Published
2021
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20. On the period collapse of a family of Ehrhart quasi-polynomials

Author

Fernandes, Cristina G., de Pina, José C., Alfonsín, Jorge L. Ramírez, and Robins, Sinai

Subjects
Mathematics - Combinatorics, Computer Science - Discrete Mathematics
Abstract

A graph whose nodes have degree 1 or 3 is called a $\{1,3\}$-graph. Liu and Osserman associated a polytope to each $\{1,3\}$-graph and studied the Ehrhart quasi-polynomials of these polytopes. They showed that the vertices of these polytopes have coordinates in the set $\{0,\frac14,\frac12,1\}$, which implies that the period of their Ehrhart quasi-polynomials is either 1, 2, or 4. We show that the period of the Ehrhart quasi-polynomial of these polytopes is at most 2 if the graph is a tree or a cubic graph, and it is equal to 4 otherwise. In the process of proving this theorem, several interesting combinatorial and geometric properties of these polytopes were uncovered, arising from the structure of their associated graphs. The tools developed here may find other applications in the study of Ehrhart quasi-polynomials and enumeration problems for other polytopes that arise from graphs. Additionally, we have identified some interesting connections with triangulations of 3-manifolds., Comment: 42 pages

Published
2021

22. Self-dual Maps I : antipodality

Author

Montejano, Luis, Alfonsín, Jorge L. Ramírez, and Rasskin, Ivan

Subjects
Mathematics - Combinatorics
Abstract

A self-dual map $G$ is said to be \emph{antipodally self-dual} if the dual map $G^*$ is antipodal embedded in $\mathbb{S}^2$ with respect to $G$. In this paper, we investigate necessary and/or sufficient conditions for a map to be antipodally self-dual. In particular, we present a combinatorial characterization for map $G$ to be antipodally self-dual in terms of certain \emph{involutive labelings}. The latter lead us to obtain necessary conditions for a map to be \emph{strongly involutive} (a notion relevant for its connection with convex geometric problems). We also investigate the relation of antipodally self-dual maps and the notion of \emph{ antipodally symmetric} maps. It turns out that the latter is a very helpful tool to study questions concerning the \emph{symmetry} as well as the \emph{amphicheirality} of \emph{links}.

Published
2020
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23. Primes in numerical semigroups

Author

Alfonsin, Jorge L. Ramirez and Skalba, Mariusz

Subjects
Mathematics - Number Theory, Mathematics - Combinatorics, 11D07, 11N13, 11A41
Abstract

Let 0 < a < b be two relatively prime integers and let be the numerical semigroup generated by a and b with Frobenius number g(a,b)=ab-a-b. In this note, we prove that there exists a prime number p in with p < g(a,b) when the product ab is sufficiently large. Two related conjectures are posed and discussed as well.

Published
2020

24. Especies forrajeras utilizadas bajo silvo-pastoreo en el centro de Chiapas

Author

R. Pinto, H. Gómez, B. Martínez, A. Hernández, F. Medina, L. Ortega, and L. Ramírez

Subjects
árboles forrajeros, arvenses, composición química, degradabilidad in situ, Agriculture (General), S1-972, Animal culture, SF1-1100
Abstract

Con el objetivo de conocer los usos, la composición química y degradabilidad ruminal de especies arbóreas y herbáceas del trópico mexicano, se desarrolló el presente trabajo en el Valle Central del estado de Chiapas, México. A través de entrevistas con productores se identificaron 14 leñosas y 7 herbáceas con mayor mención forrajera, así como sus múltiples usos. De éstas, el contenido de PC varió de medio a alto (5.8-28.7%), sobresaliendo las especies herbáceas, el contenido de MO fue muy similar entre especies (79.1 96.6%) y los niveles más altos de FDN y FDA se encontraron en los frutos y las mayores concentraciones de FT en los follajes arbóreos. En términos de degradabilidad a 24 h de la PC, MS y MO, sobresalieron el follaje de G. americana y el fruto de E. cyclocarpum (P

Published
2004

25. Atmospheric density uncertainty effects on the orbital lifetime estimation for CubeSats at LEO

Author

Jara, D. J. Cubillos, Torrico, J. A. Soliz, and Suárez, O. L. Ramírez

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

Nanosatellites, and especially CubeSats, at low earth orbits (LEOs) are a low cost option for monitoring atmospheric and environmental conditions around Earth. For instance, data for weather forecast reports can be obtained periodically with these kind of small satellites. Therefore, to academic institutions, universities, etc., this fact makes nanosatellites a very attractive way for researching with a moderate budget. In this project we compute orbital lifetimes (or simply lifetimes) for hypothetical missions involving nanosatellites at LEO, focusing our attention on exploring regions along the equatorial line. Thus, in the framework of orbital mechanics, we show the viability for these kind of missions in a long and a short term. Applications are projected for countries in northern South America, central Africa and islands/countries in southern Asia. To compute lifetimes, we take into account three effects: i) gravitational, ii) Earth deformations and iii) atmospheric density. These effects are included in the motion equation for a nanosatellite around Earth. After solving this equation for initial altitudes in 200-800 km above mean sea level (AMSL), we compute and report flight times to arrive at 150 km AMSL. These results are defined here as lifetimes and they are calculated for different atmospheric-density profiles according to experimental data and estimations. In conclusion, we find lowest and highest lifetimes for hypothetical missions involving small satellites at LEO orbiting along the equatorial line, and propose upper limits for density relative uncertainties in order to estimate reliable lifetimes., Comment: 12 pages

Published
2017

26. Numerical semigroups II: pseudo-symmetric AA-Semigroups

Author

García-Marco, Ignacio, Alfonsín, Jorge L. Ramírez, and Rodseth, Oystein J.

Subjects
Mathematics - Commutative Algebra, Mathematics - Combinatorics, Mathematics - Group Theory, 05A15, 13P10, 20M14
Abstract

This paper is a continuation of the paper "Numerical Semigroups: Ap\'ery Sets and Hilbert Series". We consider the general numerical AA-semigroup, i.e., semigroups consisting of all non-negative integer linear combinations of relatively prime positive integers of the form $a,a+d,a+2d,\dots,a+kd,c$. We first prove that, in contrast to arbitrary numerical semigroups, there exists an upper bound for the type of AA-semigroups that only depends on the number of generators of the semigroup. We then present two characterizations of pseudo-symmetric AA-semigroups. The first one leads to a polynomial time algorithm to decide whether an AA-semigroup is pseudo-symmetric. The second one gives a method to construct pseudo-symmetric AA-semigroups and provides explicit families of pseudo-symmetric semigroups with arbitrarily large number of generators., Comment: 11 pages

Published
2016

28. Supersymmetric inversion of effective-range expansions

Author

Midya, Bikashkali, Evrard, Jérémie, Abramowicz, Sylvain, Suárez, O. L. Ramírez, and Sparenberg, Jean-Marc

Subjects
Quantum Physics, Nuclear Theory, Physics - Atomic Physics
Abstract

A complete and consistent inversion technique is proposed to derive an accurate interaction potential from an effective-range function for a given partial wave in the neutral case. First, the effective-range function is Taylor or Pad\'e expanded, which allows high precision fitting of the experimental scattering phase shifts with a minimal number of parameters on a large energy range. Second, the corresponding poles of the scattering matrix are extracted in the complex wave-number plane. Third, the interaction potential is constructed with supersymmetric transformations of the radial Schr\"odinger equation. As an illustration, the method is applied to the experimental phase shifts of the neutron-proton elastic scattering in the $^1S_0$ and $^1D_2$ channels on the $[0-350]$ MeV laboratory energy interval.

Published
2015
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29. Detecting minors in matroids through triangles

Author

Albar, Boris, Gonçalves, Daniel, and Alfonsín, Jorge L. Ramírez

Subjects
Mathematics - Combinatorics
Abstract

In this note we investigate some matroid minor structure results. In particular, we present sufficient conditions, in terms of {\em triangles}, for a matroid to have either $U_{2,4}$ or $F_7$ or $M(K_5)$ as a minor., Comment: 8 pages

Published
2014

31. Precise determination of the effective-range parameters up to an arbitrary order

Author

Suárez, O. L. Ramírez and Sparenberg, J-M.

Subjects
Nuclear Theory
Abstract

We propose a method to compute, for a given potential model, an arbitrary coefficient of the effective-range function expanded as a power series in energy. The method is based on a set of recurrence relations at low energy, that allows a compact and general description to any order in energy for neutral and charged cases. By using the Lagrange mesh technique to compute the R-matrix at zero energy, this proposal permits to compute, with a very good precision, the effective-range parameters. We use a potential model for some nuclear systems to illustrate the effectiveness of this method and to discuss its numerical limitations., Comment: Keywords: scattering length, effective range, shape parameter, effective-range parameters and phase-shifts. 13 pages, 6 figures

Published
2013
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33. Matroid base polytope decomposition

Author

Chatelain, V. and Alfonsin, J. L. Ramirez

Subjects
Mathematics - Combinatorics
Abstract

Let $P(M)$ be the matroid base polytope of a matroid $M$. A {\em matroid base polytope decomposition} of $P(M)$ is a decomposition of the form $P(M) = \bigcup\limits_{i=1}^t P(M_{i})$ where each $P(M_i)$ is also a matroid base polytope for some matroid $M_i$, and for each $1\le i \neq j\le t$, the intersection $P(M_{i}) \cap P(M_{j})$ is a face of both $P(M_i)$ and $P(M_j)$. In this paper, we investigate {\em hyperplane splits}, that is, polytope decompositions when $t=2$. We give sufficient conditions for $M$ so $P(M)$ has a hyperplane split and characterize when $P(M_1 \oplus M_2)$ has a hyperplane split where $M_1 \oplus M_2$ denote the {\em direct sum} of matroids $M_1$ and $M_2$. We also prove that $P(M)$ has not a hyperplane split if $M$ is binary. Finally, we show that $P(M)$ has not a decomposition if its 1-skeleton is the {\em hypercube}., Comment: 23 pages

Published
2009

36. Numerical Analysis of the Seismic Behavior of a Steel Beam-to-Concrete-Filled Steel Tubular Column Connection Using External Diaphragms

Author

Cristhian Ramírez Ortiz, Albio D. Gutierrez Amador, and Jose L. Ramírez Duque

Subjects
beam-to-column connections, composite structures, cyclic loading, plastic hinge, special moment frames, numerical models, Building construction, TH1-9745
Abstract

The seismic behavior of a novel steel beam-to-concrete-filled steel tubular column connection with external diaphragms was evaluated numerically by using a model based on the finite element method. The model was validated against experimental results performed in previous work, which revealed that this type of connection is suitable for use in special moment frame structures located in areas of high seismic threat. The comparison included the hysteresis curve, plasticization mechanism, and plastic hinge location. Then, the model was used to study the behavior of the connection for a monotonic test. It was observed that the monotonic test can be used for the qualification of the connection, avoiding the excessive time required for the solution of the cyclic load test. In addition, two stages of simplifications were conducted in the model, showing satisfactory results and significant reductions in computational time. For the first stage, the lateral support beam was removed and replaced by a connection with an infinite lateral rigidity. Second, beam-type elements were implemented in the remote areas of the plastic hinge location. Finally, the simplified model was used in a parametric study that examined the behavior of the connection under four different European type I profiles. It was observed that all the profiles meet the requirements for seismic performance.

Published
2022
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38. Lupus Eritematoso Sistémico y Manifestaciones en el Sistema Nervioso Central: Un desafío diagnóstico permanente. Casos Clínicos

Author

L. RAMÍREZ, C. GALLO, M. GODOY, and D. PACHECO

Abstract

La presencia de manifestaciones neuropsiquiátricas en pacientes reumatológicos trae consigo un gran desafío diagnóstico que exige una mirada amplia, desde las bases de la medicina interna, a fin de poder orientar un estudio adecuado y el tratamiento oportuno. Junto con ello, el permanente diálogo e intercambio de miradas clínicas con otras especialidades permite tener un enfoque multidisciplinario que enriquece el abordaje de estas presentaciones complejas.

Published
2023

42. Potencialidades de los pastos en los sistemas de producción de la agricultura familiar en la provincia de Los Ríos, Ecuador, en el verano

Author

Emma D. Torres-Navarrete, Adolfo R. Sánchez-Laiño, Danis M. Verdecia-Acosta, Jorge L. Ramírez-de la Ribera, Luis G. Hernández-Montiel, Gustavo Curaqueo-Fuente, and Samir A. Zambrano-Montes

Subjects
digestibilidad, conglomerate, digestibility, Chemical composition, Composición química, pastos, energía, conglomerado, pastures, energy
Abstract

The aim of this study is to determine the potentialities of the most used grasses in family production systems in Los Ríos province, Ecuador, during the summer. The study was carried out in research areas and in the Ruminology and Nutritional Metabolism Laboratory of the Quevedo State Technical University. The species most used in livestock systems were selected to carry out studies of productive behavior (total biomass, total DMY, leaves and stems) and quality (DM, CP, ashes, OM, P, Ca, NDF, ADF, Lignin, Cel, Hcel, CC, IVDMD, ISDMD, OMD, ME and NLE), which underwent cluster analysis to group species with similarity. For production and chemical composition, three main components were obtained with eigenvalues greater than one and that explain 87.27 % of the variability between varieties. In component one, 11 indicators related to protein, energy and the structural components of the cell were shown with values of preponderance greater than 0.75. For the cluster analysis, five groups were formed, with the best results for the third group, made up of M. maximus with high values in CP, leaf/stem ratio, ISDMD and ME. All this information would contribute to the design of technological alternatives for sowing, establishment, management, and use of its biomass as a food source where the productivity and sustainability of the ecosystem are minimized., El objetivo de este estudio es determinar las potencialidades de los pastos más utilizados en los sistemas de producción familiar en la provincia de Los Ríos, Ecuador, durante el verano. El estudio se realizó en áreas de investigación y en el Laboratorio de Ruminología y Metabolismo Nutricional de la Universidad Técnica Estatal de Quevedo. Las especies más utilizadas en los sistemas ganaderos fueron seleccionadas para realizar estudios de comportamiento productivo (biomasa total, RMS total, hojas y tallos) calidad (MS, PB, cenizas, MO, P, Ca, FDN, FDA, LAD, Cel, Hcel, CC, TT, FT, TCT, DIVMS, DISMS, DMO, EM y ENL), a las que se les realizaron análisis de conglomerados para agrupar especies con similitud. Para la producción y composición química se obtuvieron tres componentes principales con valores propios superiores a uno y que explican 87.27 % de la variabilidad entre las variedades. En el componente uno se mostraron 11 indicadores relacionados con proteína, energía y los componentes estructurales de la célula con valores de preponderancia mayor de 0.75. Para el análisis de conglomerados se formaron cinco grupos, con los mejores resultados para el tercer grupo, lo integró el M. maximus con valores altos en la PB, relación hoja/tallo, DISMS y EM. Toda esta información contribuiría al diseño de alternativas tecnológicas para siembra, establecimiento, manejo y uso de su biomasa como fuente de alimento donde se minimiza la productividad y la sostenibilidad del ecosistema.

Published
2023
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43. Registros recientes del grisón (Galictis vittata) y el tigrillo (Leopardus wiedii) en la Sierra Nororiental de Puebla, México

Author

Julio César Hernández Hernández, José L. Ramírez-Morales Ramírez-Morales, and Jazmín Cobos-Silva

Subjects
General Medicine
Abstract

El grisón (Galictis vittata) y el tigrillo o margay (Leopardus wiedii) son dos especies del orden carnivora que presentan vacíos de información en cuanto a su distribución geográfica. En este trabajo presentamos registros recientes del grisón y del tigrillo en la Sierra Nororiental del estado de Puebla, México. Nuestros registros se basan en fotografías obtenidas mediante fototrampeo en un bosque mesófilo de montaña con fragmentos de vegetación secundaria. Aunque la presencia del grisón y tigrillo ya ha sido documentada en el norte del estado de Puebla, es de resaltar que los presentes registros llenan vacíos de información sobre la presencia de ambas especies en la Sierra Nororiental del estado de Puebla, una región reconocida por su alta biodiversidad.

Published
2022

46. Sine-based lattice plates: additive manufacturing and their mechanical properties when loaded out of plane

Author

Diana L. Ramírez-Gutiérrez, Enrique Cuan-Urquizo, and Rita Q. Fuentes-Aguilar

Subjects
Mechanical Engineering, Industrial and Manufacturing Engineering
Abstract

Purpose Demanding applications could benefit from the mathematical parametrization of lattice structures as this could lead not only to the characterization of structure–property relation but also facilitates the tailoring of the effective mechanical properties. This paper aims to characterize the mechanical performance of sine-based lattices. The characterization includes the results of in-plane Poisson’s ratio plates models, and the stiffness of additively manufactured lattice plates when loaded in the out-of-plane direction, with the objective of obtaining a relation with their geometrical parameters. Design/methodology/approach The geometrical parameter–Poisson’s ratio relationship was characterized via finite element (FE) simulations. The stiffness was also measured on additively manufactured polylactic acid lattice plates and contrasted with FE computations. Findings The characterization of auxetic lattice plates performed using in-plane and out-of-plane loading leads to key properties when deciding the geometry specific for applications: relative density, auxetic behavior and stiffness. Approximately 26% reduction of stiffness was observed between the square lattice and sine-based lattices of the same volume fraction. Originality/value Auxetic metamaterials are potential candidates for applications in biomedical engineering, smart sensors, sports and soft robotics. This paper aims to contribute to the existing gap in the study of auxetic metamaterials subjected to complex loading conditions, other than simple tension and compression, required for the mentioned applications.

Published
2023

48. Down‐Regulation–Resistant STAT4 Risk Haplotype Contributes to Lupus Nephritis Through CD4+ T Cell Interferon‐γ Production

Author

Iris K. Madera‐Salcedo, Ada L. Ramírez‐Sánchez, Noé Rodríguez‐Rodríguez, Roberto García‐Quintero, Rosa M. Rubio, Gabriela Morales‐Montes de Oca, Emmanuel Dávalos, Rogelio Cuervo, Janette Furuzawa‐Carballeda, Jorge Alcocer‐Varela, Diana Gómez‐Martín, Marysol González‐Yáñez, Abigail de la Cruz, Adrián Albarrán‐Godínez, Gerardo Suárez‐Rojas, Juanita Romero‐Díaz, Norma O. Uribe‐Uribe, Marta Alarcón‐Riquelme, Mayra Furlan‐Magaril, Juan Manuel Mejía‐Vilet, José C. Crispín, and Florencia Rosetti

Subjects
Rheumatology, Immunology, Immunology and Allergy
Abstract

Variants in STAT4 are associated with systemic lupus erythematosus (SLE) and other autoimmune diseases. How disease-associated variants affect STAT4 expression, in particular in CD4 T cells where STAT4 plays an essential role, is unknown.We compared Th1 differentiation between naïve CD4 T cells from healthy donors (HD) homozygous for the risk (R/R) or non-risk (NR/NR) alleles. We analyzed epigenetic marks in STAT4 and evaluated the relevance of its third intron. We assessed the consequences of Stat4 overexpression in vivo. We analyzed the effects of the STAT4 genotype in patients with lupus nephritis.Naïve CD4 T cells from NR/NR HD, downregulated STAT4 in response to IL-12. In contrast, cells from R/R HD maintained high levels. R/R cells exhibited higher abundance of transcriptionally active STAT4 and increased IFN-γ production. Accordingly, R/R HD exhibited a stronger induction of local active enhancer marks. Genetic editing confirmed the presence of a negative regulatory region in the STAT4 third intron, where most of the SLE-associated STAT4 SNPs are located. In vivo forced expression demonstrated that increases in Stat4 levels in T cells enhanced glomerulonephritis. Accordingly, the R/R genotype was associated with suboptimal response to treatment and with worse clinical outcomes in patients with proliferative lupus nephritis.The SLE-associated STAT4 haplotype is associated with abnormal IL-12-mediated STAT4 transcriptional regulation. Carriers of the risk variant exhibit exaggerated CD4 pro-inflammatory capacities that, in the context of SLE, contribute to a more severe disease. R/R patients may benefit from blockade of the IL-12-STAT4 pathway. This article is protected by copyright. All rights reserved.

Published
2023

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