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1,262 results on '"Nathan, Robert"'

8. NAxtra magnetic nanoparticles for low-cost, efficient isolation of mammalian DNA and RNA

Author

Eirin Johannessen Starheim, Erlend Ravlo, Jørn-Ove Schjølberg, Vanessa Solvang, Wei Wang, Nathan Robert Scrimgeour, Adeel Manaf, Sten Even Erlandsen, Per Arne Aas, Lars Hagen, Mirta Mittelstedt Leal de Sousa, and Magnar Bjørås

Subjects
Medicine, Science
Abstract

Abstract A cost-effective, viral nucleic acid (NA) isolation kit based on NAxtra magnetic nanoparticles was developed at the Norwegian University of Science and Technology in response to the shortage of commercial kits for isolation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA during the coronavirus disease 2019 (COVID-19) pandemic. This method showed comparable sensitivity to available kits at significantly reduced cost, making its application for other biological sources an intriguing prospect. Thus, based on this low-cost nucleic acid extraction technology, we developed a simple, low- and high-throughput, efficient method for isolation of high-integrity total NA, DNA and RNA from mammalian cell lines (monolayer) and organoids (3D-cultures). The extracted NA are compatible with downstream applications including (RT-)qPCR and next-generation sequencing. When automated, NA isolation can be performed in 14 min for up to 96 samples, yielding similar quantities to available kits.

Published
2023
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10. Publications, Citations and Impact Factors

Author

Nathan, Robert Jeyakumar and Shawkataly, Omar Bin

Abstract

This article discusses the role of university academics as researchers. In present-day society which touts instant gratification, the primary role of a university is being undermined. In Malaysia, academics no longer teach and research as they please but are 'guided' by government agencies and influenced by the priorities of funding agencies. One of the components of academic freedom is the freedom to publish. Academics publish research that pushes the boundaries of knowledge. They choose journals in which their articles will be peer-reviewed, published and read by the communities of interest. However, lately many academics tend to publish in journals based on rankings, in journals reputed to have higher impact than others. Often young academics are puzzled whether they should publish where it matters or where it would quickly boost the key performance indicators (KPIs) set by the university. This article highlights some of these struggles in modern academia and exposes several examples of academic misconduct.

Published
2019

18. Mepolizumab for chronic rhinosinusitis with nasal polyps (SYNAPSE): a randomised, double-blind, placebo-controlled, phase 3 trial

Author

Ahlström Emanuelsson, Cecilia, Ardusso, Ledit, Armstrong, Michael, Bardin, Philip, Barnes, Sara, Bergna, Miguel, Betz, Christian, Beule, Achim, Blotter, James, Bronescu, Valeriu, Brown, Matthew, Carrie, Sean, Chaker, Adam, Cho, Hyung-Ju, Corriveau, Marie-Noëlle, Courville, Timothy, Cuevas, Mandy, Damask, Cecelia, DeConde, Adam, Del Carpio, Jaime, De Salvo, María, Dhong, Hun-Jong, Durham, Stephen, Edin, Anton, Ehmer Jr, Dale, Elías, Pedro, Fatakia, Adil, Franzese, Christine, Gane, Simon, García, Gabriel, Gillman, Andrew, Groeger, Moritz, Harvey, Richard, Hellgren, Johan, Higgins, Thomas, Hobson, Jonathan, Jangard, Mattias, Janjua, Arif, Kara, Naveed, Karpischenko, Sergey, Kerwin, Edward, Khanova, Fatimat, Kilty, Shaun, Kim, Chang-Hoon, Kim, Seontae, Klimek, Ludger, LaForce, Craig, Leong, Samuel, Marple, Bradley, Mårtensson, Anders, Maspero, Jorge, Massey, Neil, Matz, Jonathan, McDuffie, Chad, Mella, Corina, Miller, Steven, Mirzabekyan, Ekaterina, Moss, Jonathan, Mumneh, Nayla, Nathan, Robert, Neagos, Adriana, Olze, Heidi, Ovchinnikov, Andrey, Ow, Randall, Polyakov, Dmitriy, Radeanu, Doinel, Rhee, Chae-Seo, Rojas, Ramón, Rosenbloom, Jeffrey, Ryazantsev, Sergei, Sader, Chady, Saez Scherbovsky, Pablo, Scadding, Guy, Schlosser, Rodney, Shah-Patel, Heena, Shealy, Ronald, Siddiqi, Ayesha, Silvers, Stacey, Singh, Narinder, Sommer, Doron, Soong, Weily, Sowerby, Leigh, Spafford, Peter, Stefan, Catalin, Sterling, Richard, Svistushkin, Valeriy, Talreja, Neetu, Tarasova, Galina, Tarpay, Martha, Tolcachier, Alberto, Toll, Karin Toll, van Schaik, Carolina, Webb, Luke, Wedner, H James, Wehbe, Luis, Whan Kim, Soo, Wollenberg, Barbara, Wright, Simon, Yakusevich, Vladimir, Yañez, Anahí, Yarin, Yury, Yen, David, Yeol Kim, Hyo, Han, Joseph K, Bachert, Claus, Fokkens, Wytske, Desrosiers, Martin, Wagenmann, Martin, Lee, Stella E, Smith, Steven G, Martin, Neil, Mayer, Bhabita, Yancey, Steven W, Sousa, Ana R, Chan, Robert, and Hopkins, Claire

Published
2021
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20. Phase change thermal storage: Cooking with more power and versatility

Author

Osei, Martin, Staveland, Owen, McGowan, Sean, Unger, Justin Brett, Christler, Nathan Robert, Weeman, Matthew, Strutz, Marcus Edward, Walker, Matthew, Maun, Megan Belle, Dunning, Nicolas C., Bekheit, Marcorios M., Abraham, Jon Christian Papa, Cox, Liam, Gius, Grace, Hansel, Olivia, Amoafo, Emmanuel Osei, Hugo, Nichole, and Schwartz, Pete

Published
2021
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21. Procedural Justice, Perceived Organisational Support, and Organisational Citizenship Behaviour in Business School

Author

Dominic Elizabeth, Victor Vijay, Nathan Robert Jeyakumar, and Loganathan Swetha

Subjects
organisational citizenship behaviour, perceived organisational support, procedural justice, business school, india, Business, HF5001-6182
Abstract

Background/Purpose: The effectiveness of a Business School depends on the extra role behaviours or Organ-isational Citizenship Behaviour (OCB) of its committed academics. The social exchange theory postulates that employees tend to display OCB when they know how their organisation would treat them. As B-School academics’ inclination towards OCB is less understood, this study examines the interaction between Procedural Justice (PJ), Perceived Organisational Support (POS) and Organisational Citizenship Behaviour (OCB) among B-School academics.

Published
2021
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22. Efficacy and safety of once-daily single-inhaler triple therapy (FF/UMEC/VI) versus FF/VI in patients with inadequately controlled asthma (CAPTAIN): a double-blind, randomised, phase 3A trial

Author

Lee, Laurie A, Bailes, Zelie, Barnes, Neil, Boulet, Louis-Philippe, Edwards, Dawn, Fowler, Andrew, Hanania, Nicola A, Kerstjens, Huib A M, Kerwin, Edward, Nathan, Robert, Oppenheimer, John, Papi, Alberto, Pascoe, Steven, Brusselle, Guy, Peachey, Guy, Sule, Neal, Tabberer, Maggie, and Pavord, Ian D

Published
2021
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24. Implementation of an Evidence-Based Treatment Protocol and Order Set for Alcohol Withdrawal Syndrome.

Author

Luzum, Nathan Robert, Beckius, Anna, Heinrich, Thomas W., and Stoner, Kimberly

Abstract

Background: Alcohol withdrawal syndrome (AWS) is highly prevalent in hospital inpatients. Recent evidence supports use of phenobarbital and gabapentin in certain patients, and screening tools for severe withdrawal risk can be used to guide care. Inpatients with AWS should also be considered for evidence-based treatment for alcohol use disorder (AUD). Purpose: The purpose of this quality improvement study was to monitor clinical outcomes and prescribing habits after updating an electronic order set for inpatient AWS management at a large, academic hospital. Methods: Protocol updates included use of the Prediction of Alcohol Withdrawal Severity Scale, phenobarbital and gabapentin protocols, and linkage to treatment resources. Data were collected for 10 months before and 14 months after implementation. Results: Intensive care unit (ICU) transfer rate decreased by 2.3%, whereas length of stay and readmissions were not significantly different. In patients treated with the order set, ICU transfer and length of stay outcomes were superior. Patients treated through the order set were more likely to receive evidence-based treatment for AWS and AUD. Conclusions: Electronic order sets can promote evidence-based practice for AWS. The updated protocol will remain in place at the study institution, with future efforts focused on education and ease of use to increase order set utilization. [ABSTRACT FROM AUTHOR]

Published
2024
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30. Universities at the Crossroads: Industry or Society Driven?

Author

Nathan, Robert Jeyakumar, Siang, Terence Tan Gek, and Shawkataly, Omar

Abstract

Higher education is viewed as part of the national agenda in transforming Malaysia into a high-income nation. This has resulted in a sky-rocketing number of graduates in Malaysia's recent history. Industry relies on higher education as the source of skilled employees, and it is important for industry to attract and retain talented employees in their effort to remain competitive in the market. This article presents an overview of the higher education system in Malaysia that has in the recent years jumped onto the "industry-driven" wagon. The impacts of both industry-driven and society-driven systems are discussed. The article concludes with practical recommendations for higher education institutions in Malaysia to encourage a balanced higher education policy and strategy that can blend industry-driven and society-driven approaches as a joint-agenda for institutions of higher learning.

Published
2013

31. Low-dose aspirin for the prevention of preterm delivery in nulliparous women with a singleton pregnancy (ASPIRIN): a randomised, double-blind, placebo-controlled trial

Author

Achieng, Emmah, Bauserman, Melissa, Bose, Carl, Bucher, Sherri, Carlo, Waldemar, Charantimath, Umesh S, Chicuy, Javier, Chomba, Elwyn, Das, Prabir, Derman, Richard, Esamai, Fabian, Figueroa, Lester, Ganachari, MS, Garces, Ana, Goco, Noman, Goldenberg, Robert, Goudar, Shivaprasad, Hemingway-Foday, Jennifer, Hibberd, Patricia, Hoffman, Matthew, Honnungar, Narayan V, Jessani, Saleem, Kavi, Avinash, Kodkany, Bhalachandra, Koso-Thomas, Marion, Krebs, Nancy, Kumar Shashikanth, Yogesh, Kurhe, Kunal, Liechty, Edward, Lokangaka, Adrien, MacGuire, Emily, Mallapur, Ashalata A, McClure, Elizabeth, Metgud, Mrityunjay, Miodovnik, Menachem, Moore, Janet, Mwapule, Abigail, Mwenechanya, Musaku, Naqvi, Farnaz, Naqvi, Seemab, Nathan, Robert, Nolen, Tracy, Nyongesa, Paul, Okitawutshu, Jean, Parepalli, Suchita, Patel, Archana, Ramadurg, Umesh Y, Saleem, Sarah, Silver, Robert, Somannavar, Manjunath, Soomro, Zahid, Tshefu, Antoinette, Vernekar, Sunil S, Wallace, Dennis, Zehra, Farnaz, Hoffman, Matthew K, Goudar, Shivaprasad S, Kodkany, Bhalachandra S, Bose, Carl L, Carlo, Waldemar A, Krebs, Nancy F, Goldenberg, Robert L, Hibberd, Patricia L, Liechty, Edward A, Goco, Norman, Nolen, Tracy L, McClure, Elizabeth M, Silver, R, and Derman, Richard J

Published
2020
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35. Including ultrasound scans in antenatal care in low-resource settings: Considering the complementarity of obstetric ultrasound screening and maternity waiting homes in strengthening referral systems in low-resource, rural settings

Author

Swanson, David L., Franklin, Holly L., Swanson, Jonathan O., Goldenberg, Robert L., McClure, Elizabeth M., Mirza, Waseem, Muyodi, David, Figueroa, Lester, Goldsmith, Nicole, Kanaiza, Nancy, Naqvi, Farnaz, Pineda, Irma Sayury, López-Gomez, Walter, Hamsumonde, Dorothy, Bolamba, Victor Lokomba, Newman, Jamie E., Fogleman, Elizabeth V., Saleem, Sarah, Esamai, Fabian, Bucher, Sherri, Liechty, Edward A., Garces, Ana L., Krebs, Nancy F., Hambidge, K. Michael, Chomba, Elwyn, Bauserman, Melissa, Mwenechanya, Musaku, Carlo, Waldemar A., Tshefu, Antoinette, Lokangaka, Adrien, Bose, Carl L., and Nathan, Robert O.

Published
2019
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39. Long-term safety and efficacy of benralizumab in patients with severe, uncontrolled asthma: 1-year results from the BORA phase 3 extension trial

Author

Yañez, Anahí, Fernández, Marcelo, Tolcachier, Alberto, Belloni, Juan, Taborda, Jorge, De Salvo, Maria, Maspero, Jorge, Victorio, Carlos, Navarta, Miguel Chirino, Grilli, Monica, Rodríguez, Pablo, Otaola, María, Cambursano, Víctor, Malamud, Patricia, Stok, Ana, Arce, German, Roza, Osiris, Scherbovsky, Fernando, Elias, Pedro, Saez, Maria Salazan, Peters, Matthew, Phillips, Martin, Upham, John, Gibson, Peter, Thien, Francis, Douglass, Jo, Thomas, Paul, Bardin, Philip, Sajkov, Dimitar, Hew, Mark, Langton, David, Pez, Andreia, Fritscher, Carlos, Hetzel, Jorge, Mattos, Waldo, Stelmach, Rafael, Antila, Martti, Fernandes, Ana Luisa, Metev, Hristo, Ivanov, Yavor, Bogdanova, Aneliya, Markova, Ana Dancheva, Peneva, Marinka, Veselinova, Rumyana, Petkova, Tatyana, Petrova, Vanushka, Shopova, Elena, Ivanova, Yuliya, Yotsova, Rumyana, Kirkova, Ginka, Petrova, Galina, Dachev, Svetoslav, Sotirova, Kostadinka, Stoyanova, Mariyana, Yakov, Oleg, Ilieva-Fartunova, Vanya, Lemiere, Catherine, Laviolette, Michel, Yang, William, FitzGerald, J Mark, Pek, Bonavuth, Killorn, William Patrick, Poirier, Claude, Chouinard, Guy, Melenka, Lyle, Leigh, Richard, Nair, Parameswaran, Dorscheid, Delbert, Martin, James, Pavie, Juana, Rosenblut, Andres, Cartagena, Claudia, Quilodran, Carlos, Muñoz, Silvia, Malkusova, Ivana, Veverka, Josef, Holub, Stanislav, Mares, Jaroslav, Kozel, Radovan, Kopecka, Daniela, Zindr, Vladimir, Cerva, Pavel, Chanez, Pascal, Bourdin, Arnaud, Devouassoux, Gilles, Taille, Camille, De Blay, Frédéric, Goupil, Francois, Leroyer, Christophe, Gourcerol, Delphine, Didi, Toufik, Didier, Alain, Garcia, Gilles, Bonniaud, Philippe, Vasram, Riazate Rossanaly, Lommatzsch, Marek, Harnest, Ulf, Linnhoff, Anneliese, Keller, Claus, Hoheisel, Gerhard, Förster, Karin, Schultz, Thomas, Schenkenberger, Isabelle, Kirschner, Joachim, Schmoller, Tibor, Zielen, Stefan, Kornmann, Marc, Beck, Ekkehard, Volgmann, Lutz, Dichmann, Rolf, Overlack, Axel, Winkler, Jörg, Mikloweit, Petra, Ballenberger, Sabine, Rolke, Mathias, Korn, Stephanie, Pabel, Helmut, Hoffmann, Martin, Feimer, Jan, Rabe, Klaus, Deckelmann, Regina, Welte, Tobias, Ohbayashi, Hiroyuki, Hozawa, Soichiro, Shimoda, Terufumi, Yoshida, Makoto, Nagakura, Toshikazu, Kamei, Tadashi, Sano, Yasuyuki, Kagami, Shinichiro, Takahashi, Hisaho, Haida, Michiko, Kimura, Goro, Nakamura, Hiroyuki, To, Yasuo, Shinkai, Masaharu, Shimokawaji, Tadasuke, Kudo, Makoto, Shijyubo, Noriharu, Tochigi, Takao, Kato, Motokazu, Tanaka, Akihiko, Gon, Yasuhiro, Sasaki, Norihisa, Ohdaira, Tetsuro, Omori, Chiharu, Takahashi, Toshiki, Takeuchi, Satomi, Nakajima, Kiyotaka, Makita, Hironi, Kaneko, Masahiro, Furuta, Kenjiro, Taniguchi, Masami, Inobe, Yoshito, Miki, Hiroshi, Nakamura, Yoichi, Miyazawa, Naoki, Yano, Shuichi, Iijima, Masayuki, Yamato, Tsuyoshi, Diaz, Javier, Matsuno, Alberto, Felix, Efrain, Guerreros, Alfredo, Daly, Alejandro, Rodriguez Chariarse, Fernando, Salazar, Danilo, Castro, Socorro, Chavez, William, Estrella, Rolando, Aquino, Teresita, Atienza, Tito, Samoro, Ronnie, Isidro, Marie Grace Dawn, Kuna, Piotr, Antczak, Adam, Bednarek, Michał, Mądra-Rogacka, Danuta, Hofman, Teresa, Jutel, Marek, Pisarczyk-Bogacka, Ewa, Kot, Agata, Mróz, Robert, Czupryńska-Borkowska, Małgorzata, Żurowska-Gębala, Małgorzata, Dyczek, Andrzej, Jasieniak-Pinis, Grażyna, Wojnowski, Piotr, Trębas-Pietraś, Ewa, Dobryniewska, Małgorzata, Stobiecki, Marcin, Tarnowska-Matusiak, Marzenna, Magner, Alina, Kolczyński, Andrzej, Kachel, Tomasz, Bartuzi, Zbigniew, Majorek-Olechowska, Bernadetta, Śliwiński, Paweł, Balicka, Violetta, Hajoł, Elżbieta, Stachera, Jacek, Rachel, Marta, Michnar, Marek, Tałałaj, Jarosław, Springer, Ewa, Napora, Piotr, Grzelewski, Tomasz, Bijata-Bronisz, Renata, Świderska, Anna, Mincewicz, Grzegorz, Sankowski, Zbigniew, Fijołek, Tomasz, Kwaśniewski, Artur, Jerzyńska, Joanna, Cygler, Jerzy, Olesiejuk, Ryszard, Von Steiner, Iwona, Machowiak, Wojciech, Filipek, Krzysztof, Piskorz, Piotr, Uhryn, Ewa, Nittner-Marszalska, Marita, Rybicka-Liszewska, Elżbieta, Bodzenta-Łukaszyk, Anna, Chełmińska, Marta, Krupa-Borek, Izabella, Skucha, Wojciech, Płoszczuk, Anna, Mihaescu, Traian, Petrui, Ioan Dorin, Savu, Angelica, Apti, Ghiulten, Toma, Claudia, Trailescu, Ana, Sokurenko, Sergei, Trofimov, Vasiliy, Leshchenko, Igor, Shaporova, Natalia, Ilyashevich, Inna, Stitsenko, Irina, Vizel, Alexander, Ilkovich, Yulia, Tikhanov, Dmitrii, Goncharova, Svetlana, Ezhov, Andrey, Ignatova, Galina, Izmozherova, Nadezhda, Berdnikova, Nadezhda, Goryachkina, Ludmila, Popova, Veronika, Bolieva, Laura, Rebrov, Andrey, Nosov, Vladimir, Magnitskaya, Olga, Nedogoda, Sergey, Abrosimov, Vladimir, Molotkov, Artem, Reshedko, Galina, Smirnov, Mikhail, Osipenko, Marina, Pavlysh, Elena, Myasoedova, Svetlana, Lenskaya, Liudmila, Chistyakov, Valery, Vishneva, Elena, Uon, Liliya, Zateyschikova, Anna, Laleko, Svetlana, Pak, Tatiana, Bruning, Axel, Naidoo, Visvakuren, Reddy, Jeevren, Van Zyl Smit, Richard, Park, Hae-Sim, Cho, Young Joo, Cho, Sang-Heon, Lee, Sang Haak, Lee, Byung Jae, Kim, Ju Sang, Cho, You Sook, Park, Choon-Sik, Kim, Mi-Kyeong, Koh, Young-Il, Kim, Joo-Hee, Lee, Sook Young, Lee, Sang Pyo, Park, Jung Won, Yoo, Kwang Ha, Yoon, Hyoungkyu, Lee, Jaechun, Hur, Gyu-Young, Lee, Soo Keol, Kim, HeeKyoo, Ramos Barbón, David, Laffond Yges, Elena, Martínez Moragón, Eva, Arias Guillen, Miguel, Saura Vinuesa, Alberto, Sánchez-Toril López, Fernando, Velasco Garrido, José Luis, García-Cosio Piqueras, Borja, Pérez de Llano, Luis, Valero Santiago, Antonio Luis, Rubio, Myriam Calle, Bjermer, Leif, Lundbäck, Bo, Gemicioglu, Bilun, Bavbek, Sevim, Ediger, Dane, Erdinc, Munevver, Hanta, Ismail, Nayci, Sibel, Arinc, Sibel, Iashyna, Liudmyla, Mostovoy, Yuriy, Ostrovskyy, Mykola, Kuryk, Lesia, Lemko, Ivan, Ospanova, Tetyana, Moskalenko, Liubov, Korzh, Oleksii, Blazhko, Viktor, Krakhmalova, Olena, Romaniuk, Liliia, Dytyatkovs'ka, Yevgeniya, Yakovenko, Oleh, Gavrysyuk, Volodymyr, Burhan, Hassan, Saralaya, Dinesh, Scott, Stephen, Morice, Alyn, Jackson-Voyzey, Ewart, Win, Thida, Nasser, Shuab, Harrison, Richard, Chaudhuri, Rekha, Nordstrom, Monica, De, Pradip, Masoli, Matthew, Mansur, Adel, Gunstone, Anthony, Niven, Robert, Harrison, Timothy, Babu, Suresh, Bhuchar, Subodh, Kureishy, Shahrukh, Zwetchkenbaum, John, Kaplan, Lawrence, Bleecker, Eugene, Reyes, Santiago, Fakih, Faisal, Heuer, Marvin, Klein, Ryan, Marcus, Michael, Hussain, Iftikhar, Tanus, Tonny, Raissy, Hengameh, Alpizar, Sady, Rodriguez, Hector, Gleich, Gerald, Bridges, Tracy, Pouzar, Joe, Steven, Gary, Matz, Jonathan, Krstevska, Shana, Ziworitin, Dama, Kaplan, Adolfo, Sublett, James, DeAngelo, James, Darter, Amy, Agaiby, John, Hagan, John, Davis, Enrique, Siri, Dareen, Mcevoy, Charlene, Dharma, Chrisette, Karimjee, Najmuddin, Kelsen, Steven, Frade, Manuel, Silverthorn, Amy, Kline, Joel, Averill, Francis, Ruiz, Jose, Robinette, Emory, Shaikh, Zeeshan, Aguilar, Carlos, Nish, William, Alvarez, German, Ismail, Younus, Parikh, Purvi, Leong, Mila, Murphy, Dennis, Garcia, Francisco, Goldsobel, Alan, Blanco, Antonio, Campbell, Edward, Perez, Guido, Chupp, Geoffrey, Bates, Toby, Perez, Vandely, Wenzel, Sally, Shenoy, Kartik, Katial, Rohit, Bernstein, David, Parikh, Neil, Sims, William, Ferguson, Gary, Pham, David, George, Anu, Beasley, Richard, Perez, Gilberto, Garver, Robert, Garcia-Portela, Miriam, Wong, Stephen, Soong, Weily, Guillot, Richard, Hudes, Golda, Arif, Ahmed, Binker, Josefa, Villareal, Manuel, Ziegner, Ulrike, Ojile, Joseph, Goswami, Sanjeev, Piniella, Carlos, Segal, Ilia, Zafra, Heidi, Lee, Mitchell, Tarpay, Martha, Panuto, John, Merchant, Rajan, Springsteen, Peter, Scialla, Timothy, Shapero, Paul, Allen, Karen, Moss, Mark, Cruz, Humberto, Rumbyrt, Jeffrey, Boyd, Amy, Nathan, Robert, Bernstein, Jonathan, Jacobs, Joshua, Ginchansky, Elliot, Johnston, Janice, Baxter, Barbara, Johnson II, Thomas, Apaliski, Stephen, Corder, Clinton, Fuentes, David, Diaz, Joseph, Ngo, Chau, Le, Lan, Busse, William W, Bleecker, Eugene R, Ferguson, Gary T, Barker, Peter, Sproule, Stephanie, Olsson, Richard F, Martin, Ubaldo J, and Goldman, Mitchell

Published
2019
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42. An adaptive, preconditioned, electromechanical model for the simulation of cardiac arrhythmias

Author

Kirk, Nathan Robert, Hubbard, M., and Goodyer, C.

Subjects
616.128
Abstract

In this thesis a coupled model of cardiac electromechanical activity is presented, using the finite element method to model both electrophysiology and mechanics within a deforming domain. The efficiency of the electrical model was improved using adaptive mesh refinement and the mechanical system performance was improved with the addition of preconditioning. Unstructured triangular meshes were used throughout. The electrophysiology model uses the ten Tusscher-Panfilov 2006 detailed cellular model, and includes anisotropic diffusion, uses a semi-implicit time stepping scheme, stores data in an efficient sparse storage format and applies a Reverse Cuthill-McKee ordering algorithm to reduce the matrices’ bandwidths. Linear elements were used to approximate the transmembrane voltage and spatial and temporal convergence tests were undertaken. Local mesh adaptivity is added to the electrical component of the model and improvements to the performance and efficiency gained by this technique were investigated. Two different monitor functions were utilised and these demonstrated that by targeting adaptive mesh refinement at the front of the electrical wave significant efficiency and performance benefits could be achieved. The cardiac mechanical model is based on finite deformation elasticity theory, enforces the incompressibility of the tissue and incorporates anisotropic tension to simulate fibre orientation. This uses isoparametric quadratic elements for deformation, linear elements for pressure, was integrated with numerical quadrature and the resulting non-linear system solved with the iterative Newton method. Preconditioning was added to the mechanical component of the model and improvements in the performance of the solver due to this were investigated. An ILUT (Incomplete Lower Upper factorisation with drop Tolerance) preconditioner was implemented and this demonstrated performance improvements of up to 27 times on the meshes tested. The resulting cardiac electromechanical solver was then used to consider how known changes in cardiac electrophysiology, which are manifest in end-stage heart disease, affect the stability of the electrical wave. Specifically, investigations were undertaken into the introduction of fibrotic regions (with different sizes and concentrations) and electrical remodelling caused by end-stage cardiac disease. These were modelled on both static and deforming domains to consider whether deformation can alter the stability of a spiral wave. These simulations demonstrated that fibrotic regions and tissue deformation can have significant disruptive effects on the stability of a re-entrant spiral wave and that remodelling the electrophysiology stabilises the wave.

Published
2012

45. Extreme Ductility in Freestanding Glassy Polymer Thin Films

Author

Velez, Nathan Robert

Subjects
Materials Science, ductility, glassy, MEMS, nanomechanical, polymer, thin film
Abstract

In this dissertation the mechanical and thermodynamic properties of microtomed thin films of glassy polymers is investigated using unique techniques and methods developed for this purpose. The novel methodology developed led to the discovery of unexpected mechanical properties in glassy polymer thin films prepared via microtomy, primarily the extreme ductility in nominally brittle materials: polystyrene (PS) and poly(methyl methacrylate) (PMMA). To investigate the origins of this phenomenon, the technique was developed further to provide a means to probe temperature dependent properties of the films, with the specific interest in measuring the glass transition temperature (Tg). Temperature-controlled dynamic mechanical analysis (DMA) experiments were carried out, revealing Tg depression never before measured in glassy polymer thin films with thickness above 100 nm.The experimental methods are detailed in Chapter 1, beginning with the introduction of the micro-electromechanical system (MEMS) device, known as a push-to-pull (PTP) device. The PTP device was pivotal in the research herein but first required adaptations before it could be used to characterize polymeric materials, as its original design was intended for hard materials. The development of novel sample preparation techniques was also required to successfully utilize the PTP device for characterization of polymer thin films. These developments, as well as the challenges and limitations of the technique, are also outlined. This includes the topic of ion and electron beam irradiation effects, which are considerably more problematic and require additional precautions when compared to most hard materials, such as metals.Results from PTP device testing of microtomed thin films of two polymer glasses, PS and PMMA, are presented and discussed in the proceeding chapters with a primary focus on the extreme ductility observed in both materials. These results include quantitative tensile testing, in situ and postmortem optical microscopy, postmortem transmission electron microscopy (TEM), and temperature-controlled DMA testing. Aside from the extreme ductility, analysis of the stress-strain relationship revealed a significant reduction of the elastic modulus and a thickness-dependent trend with respect to the strain softening amplitude. The quality of these results was verified by in situ optical microscopy, which also allowed for larger strains to be reached. Postmortem TEM investigations provided detailed imaging of the deformation microstructure, which showed a dependence on the thermal history of the film.Analysis of these results, in concert with current theory in polymer physics, are discussed and a hypothesis to describe the underlying mechanisms at work is proposed. In short, microtomy produces films with fractured surfaces containing a high concentration of chain ends and a distribution of reduced molecular weight (Mw). These attributes are believed to enhance segmental mobility of chains not only at the surface, but also those deeper within the film. Direct evidence and theoretical support for these claims are presented and discussed in this dissertationFinally, the potential applications of these findings as well as future research opportunities enabled by the development of the novel PTP device technique described herein are examined.

Published
2021

46. NAxtra magnetic nanoparticles for low-cost, efficient isolation of mammalian DNA and RNA

Author

Starheim, Eirin Johannessen, primary, Ravlo, Erlend, additional, Schjølberg, Jørn-Ove, additional, Solvang, Vanessa, additional, Wang, Wei, additional, Scrimgeour, Nathan Robert, additional, Manaf, Adeel, additional, Erlandsen, Sten Even, additional, Aas, Per Arne, additional, Hagen, Lars, additional, de Sousa, Mirta Mittelstedt Leal, additional, and Bjørås, Magnar, additional

Published
2023
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50. Oversimplification: a reply to White

Author

Smith, Nathan Robert

Subjects
simplicity, probability, Occam's razor, Ockham's razor, confirmation
Abstract

Roger White has argued that the assumptions required to support a simplicity favoring principle are far more modest than it first seems. I criticize White's arguments and show that White requires assumptions for his arguments that are at least as controversial as the simplicity favoring principle he wishes to support.

Published
2008

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