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582 results on '"Brown, Christian"'

1. Universal properties of the evolution of the Universe in modified loop quantum cosmology

Author

Saeed, Jamal, Pan, Rui, Brown, Christian, Clevear, Gerald, and Wang, Anzhong

Subjects
General Relativity and Quantum Cosmology, Astrophysics - Cosmology and Nongalactic Astrophysics, High Energy Physics - Phenomenology, High Energy Physics - Theory
Abstract

In this paper, we systematically study the evolution of the Universe in the framework of a modified loop quantum cosmological model (mLQC-I) with various inflationary potentials, including chaotic, Starobinsky, generalized Starobinsky, polynomials of the first and second kinds, generalized T- models and natural inflation. In all these models, the big bang singularity is represented by a quantum bounce, and the evolution of the Universe both before and after the bounce is universal and weakly depends on the inflationary potentials, as long as the evolution is dominated by the kinetic energy of the inflaton at the bounce. In particular, the evolution in the pre-bounce region can be universally divided into three different phases: pre-bouncing, pre-transition, and pre-de Sitter. The pre-bouncing phase occurs immediately before the quantum bounce, during which the evolution of the Universe is dominated by the kinetic energy of the inflaton. Thus, the equation of state of the inflaton is about one, w = 1. Soon, the inflation potential takes over, so w rapidly falls from one to negative one. This pre-transition phase is very short and quickly turns into the pre-de Sitter phase, whereby the effective cosmological constant with a Planck size takes over and dominates the rest of the contracting phase. In the entire pre-bounce regime, the evolution of the expansion factor and the inflaton can be approximated by analytical solutions, which are universal and independent of the inflation potentials., Comment: 28 pages, 32 Figures

Published
2024

3. Recent cases

Author

Gardner-Hopkins, James and Brown, Christian

Published
2010

6. How a nonassociative algebra reflects the properties of a skew polynomial

Author

Brown, Christian and Pumpluen, Susanne

Subjects
Mathematics - Rings and Algebras, 16S36 (Primary), 17A60, 17A99 (Secondary)
Abstract

Let $S$ be a unital associative ring and $S[t;\sigma,\delta]$ be a skew polynomial ring, where $\sigma$ is an injective endomorphism of $S$ and $\delta$ a left $\sigma$-derivation. For each $f\in S[t;\sigma,\delta]$ of degree $m>1$ with a unit as leading coefficient, we construct a unital nonassociative algebra whose behaviour reflects the properties of $f$. The algebras obtained yield canonical examples of right division algebras when $f$ is irreducible. We investigate the structure of these algebras. The structure of their right nucleus depends on the choice of $f$. In the classical literature, this nucleus appears as the eigenspace of $f$, and is used to investigate the irreducible factors of $f$. We give necessary and sufficient criteria for skew polynomials of low degree to be irreducible., Comment: 24 pages, most of the work is part of the first author's PhD thesis (arXiv:1806.00822). Changes to first version: Section 3 has been taken out

Published
2018
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7. Irreducible skew polynomials over domains

Author

Brown, Christian and Pumpluen, Susanne

Subjects
Mathematics - Rings and Algebras, 16S36
Abstract

Let $S$ be a domain and $R=S[t;\sigma,\delta]$ a skew polynomial ring, where $\sigma$ is an injective endomorphism of $S$ and $\delta$ a left $\sigma$ -derivation. We give criteria for skew polynomials $f\in R$ of degree less or equal to four to be irreducible. We apply them to low degree polynomials in quantized Weyl algebras and the quantum planes. We also consider $f(t)=t^m-a\in R$., Comment: Updated slightly rewritten version of the previously deposited one

Published
2018

8. Petit Algebras and their Automorphisms

Author

Brown, Christian

Subjects
Mathematics - Rings and Algebras
Abstract

In this thesis, we study the properties of a nonassociative algebra construction from skew polynomial rings. This construction was introduced by Petit in the 1960s but largely ignored until recently. In particular, the automorphism groups of these algebras are studied, paying particular attention to the case when the construction yields a finite semifield. The thesis is concluded by revisiting a result on associative solvable crossed product algebras by both Petit and Albert. We show a crossed product algebra is solvable if and only if it can be written as a chain of Petit algebras satisfying certain conditions.

Published
2018

9. Nonassociative cyclic extensions of fields and central simple algebras

Author

Brown, Christian and Pumpluen, Susanne

Subjects
Mathematics - Rings and Algebras, Primary: 17A35, Secondary: 17A60, 16S36
Abstract

We define nonassociative cyclic extensions of degree m of both fields and central simple algebras over fields. If a suitable field contains a primitive mth (resp., qth) root of unity, we show that suitable nonassociative generalized cyclic division algebras yield nonassociative cyclic extensions of degree m (resp., qs). Some of Amitsur's classical results on non-commutative associative cyclic extensions of both fields and central simple algebras are obtained as special cases., Comment: 13 pages

Published
2018
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10. Developing a Diagnostic Multivariable Prediction Model for Urinary Tract Cancer in Patients Referred with Haematuria: Results from the IDENTIFY Collaborative Study

Author

Chaudry, Aasem, Sharma, Abhishek, Bennett, Adam, Ahmad, Adnan, Abroaf, Ahmed, Suliman, Ahmed Musa, Lloyd, Aimee, McKay, Alastair, Wong, Albert, Silva, Alberto, Schneider, Alexandre, MacKay, Alison, Knight, Allen, Grigorakis, Alkiviadis, Bdesha, Amar, Nagle, Amy, Cebola, Ana, Dhanasekaran, Ananda Kumar, Kondža, Andraž, Barcelos, André, Galosi, Andrea Benedetto, Ebur, Andrea, Minervini, Andrea, Russell, Andrew, Webb, Andrew, de Jalón, Ángel García, Desai, Ankit, Czech, Anna Katarzyna, Mainwaring, Anna, Adimonye, Anthony, Das, Arighno, Figueiredo, Arnaldo, Villers, Arnauld, Leminski, Artur, Chippagiri, Arvinda, Lal, Asim Ahmed, Yıldırım, Asıf, Voulgaris, Athanasios Marios, Uzan, Audrey, Oo, Aye Moh Moh, Younis, Ayman, Zelhof, Bachar, Mukhtar, Bashir, Ayres, Ben, Challacombe, Ben, Sherwood, Benedict, Ristau, Benjamin, Lai, Billy, Nellensteijn, Brechtje, Schreiter, Brielle, Trombetta, Carlo, Dowling, Catherine, Hobbs, Catherine, Benitez, Cayo Augusto Estigarribia, Lebacle, Cédric, Ho, Cherrie Wing Yin, Ng, Chi-Fai, Mount, Chloe, Lam, Chon Meng, Blick, Chris, Brown, Christian, Gallegos, Christopher, Higgs, Claire, Browne, Clíodhna, McCann, Conor, Plaza Alonso, Cristina, Beder, Daniel, Cohen, Daniel, Gordon, Daniel, Wilby, Daniel, Gordon, Danny, Hrouda, David, Lau, David Hua Wu, Karsza, Dávid, Mak, David, Martin-Way, David, Suthaharan, Denula, Patel, Dhruv, Carrion, Diego M, Nyanhongo, Donald, Bass, Edward, Mains, Edward, Chau, Edwin, Canelon Castillo, Elba, Day, Elizabeth, Desouky, Elsayed, Gaines, Emily, Papworth, Emma, Yuruk, Emrah, Kilic, Enes, Dinneen, Eoin, Palagonia, Erika, Xylinas, Evanguelos, Khawaja, Faizan, Cimarra, Fernando, Bardet, Florian, Kum, Francesca, Peters, Francesca, Kovács, Gábor, Tanasescu, Geroge, Hellawell, Giles, Tasso, Giovanni, Lam, Gitte, La Montagna, Giuseppe, Pizzuto, Giuseppe, Lenart, Gordan, MacLennan, Graeme, Özgür, Günal, Bi, Hai, Lyons, Hannah, Warren, Hannah, Ahmed, Hashim, Simpson, Helen, Burden, Helena, Gresty, Helena, Rios Pita, Hernado, Clarke, Holly, Serag, Hosam, Kynaston, Howard, Crawford-Smith, Hugh, Mostafid, Hugh, Otaola-Arca, Hugo, Koo, Hui Fen, Ibrahim, Ibrahim, Ouzaid, Idir, Puche-Sanz, Ignacio, Tomašković, Igor, Tinay, Ilker, Sahibzada, Iqbal, Thangasamy, Isaac, Cadena, Iván Revelo, Irani, Jacques, Udzik, Jakub, Brittain, James, Catto, James, Green, James, Tweedle, James, Hernando, Jamie Borrego, Leask, Jamie, Kalsi, Jas, Frankel, Jason, Toniolo, Jason, Raman, Jay D., Courcier, Jean, Kumaradeevan, Jeevan, Clark, Jennifer, Jones, Jennifer, Teoh, Jeremy Yuen-Chun, Iacovou, John, Kelly, John, Selph, John P., Aning, Jonathan, Deeks, Jon, Cobley, Jonathan, Olivier, Jonathan, Maw, Jonny, Herranz-Yagüe, José Antonio, Nolazco, Jose Ignacio, Cózar-Olmo, Jose Manuel, Bagley, Joseph, Jelski, Joseph, Norris, Joseph, Testa, Joseph, Meeks, Joshua, Hernandez, Juan, Vásquez, Juan Luis, Randhawa, Karen, Dhera, Karishma, Gronostaj, Katarzyna, Houlton, Kathleen, Lehman, Kathleen, Gillams, Kathryn, Adasonla, Kelvin, Brown, Kevin, Murtagh, Kevin, Mistry, Kiki, Davenport, Kim, Kitamura, Kosuke, Derbyshire, Laura, Clarke, Laurence, Morton, Lawrie, Martinez, Levin, Goldsmith, Louise, Paramore, Louise, Cormier, Luc, Dell'Atti, Lucio, Simmons, Lucy, Martinez-Piñeiro, Luis, Rico, Luis, Chan, Luke, Forster, Luke, Ma, Lulin, Moore, Madeline, Gallego, Maria Camacho, Freire, Maria José, Emberton, Mark, Feneley, Mark, Antón-Juanilla, Marta, Rivero, Marta Viridiana Muñoz, Pirša, Matea, Tallè, Matteo, Crockett, Matthew, Liew, Matthew, Trail, Matthew, Peters, Max, Cooper, Meghan, Kulkarni, Meghana, Ager, Michael, He, Ming, Li, Mo, Omran Breish, Mohamed, Tarin, Mohamed, Aldiwani, Mohammed, Matanhelia, Mudit, Pasha, Muhammad, Akalın, Mustafa Kaan, Abdullah, Nasreen, Hale, Nathan, Gadiyar, Neha, Kocher, Neil, Bullock, Nicholas, Campain, Nicholas, Pavan, Nicola, Al-Ibraheem, Nihad, Bhatt, Nikita, Bedi, Nishant, Shrotri, Nitin, Lobo, Niyati, Balderas, Olga, Kouli, Omar, Capoun, Otakar, Oteo Manjavacas, Pablo, Gontero, Paolo, Mariappan, Paramananthan, Marchiñena, Patricio Garcia, Erotocritou, Paul, Sweeney, Paul, Planelles, Paula, Acher, Peter, Black, Peter C., Osei-Bonsu, Peter K, Østergren, Peter, Smith, Peter, Willemse, Peter-Paul Michiel, Chlosta, Piotr L., Ul Ain, Qurrat, Barratt, Rachel, Esler, Rachel, Khalid, Raihan, Hsu, Ray, Stamirowski, Remigiusz, Mangat, Reshma, Cruz, Ricardo, Ellis, Ricky, Adams, Robert, Hessell, Robert, Oomen, Robert J.A., McConkey, Robert, Ritchie, Robert, Jarimba, Roberto, Chahal, Rohit, Andres, Rosado Mario, Hawkins, Rosalyn, David, Rotimi, Manecksha, Rustom P., Agrawal, Sachin, Hamid, Syed Sami, Deem, Samuel, Goonewardene, Sanchia, Swami, Satchi Kuchibhotla, Hori, Satoshi, Khan, Shahid, Mohammud Inder, Shakeel, Sangaralingam, Shanthi, Marathe, Shekhar, Raveenthiran, Sheliyan, Horie, Shigeo, Sengupta, Shomik, Parson, Sian, Parker, Sidney, Hawlina, Simon, Williams, Simon, Mazzoli, Simone, Grzegorz Kata, Slawomir, Pinheiro Lopes, Sofia, Ramos, Sónia, Rai, Sonpreet, Rintoul-Hoad, Sophie, O'Meara, Sorcha, Morris, Steve, Turner, Stacey, Venturini, Stefano, Almpanis, Stephanos, Joniau, Steven, Jain, Sunjay, Mallett, Susan, Nikles, Sven, Shahzad, Yan, Sylvia, Lee, Taeweon, Uçar, Taha, Drake, Tamsin, Toma, Tarq, Cabañuz Plo, Teresa, Bonnin, Thierry, Muilwijk, Tim, Wollin, Tim, Chu, Timothy Shun Man, Appanna, Timson, Brophy, Tom, Ellul, Tom, Austin, Tomas, Smrkolj, Tomaž, Rowe, Tracey, Sukhu, Troy, Patel, Trushar, Garg, Tullika, Çaşkurlu, Turhan, Bele, Uros, Haroon, Usman, Crespo-Atín, Víctor, Parejo Cortes, Victor, Capapé Poves, Victoria, Gnanapragasam, Vincent, Gauhar, Vineet, During, Vinnie, Kumar, Vivek, Fiala, Vojtech, Mahmalji, Wasim, Lam, Wayne, Fung Chin, Yew, Filtekin, Yigit, Chyn Phan, Yih, Ibrahim, Youssed, Glaser, Zachary A, Abiddin, Zainal Adwin, Qin, Zijian, Zotter, Zsuzsanna, Zainuddin, Zulkifli, Khadhouri, Sinan, Gallagher, Kevin M., MacKenzie, Kenneth R., Shah, Taimur T., Gao, Chuanyu, Moore, Sacha, Zimmermann, Eleanor F., Edison, Eric, Jefferies, Matthew, Nambiar, Arjun, Anbarasan, Thineskrishna, Mannas, Miles P., Marra, Giancarlo, Gómez Rivas, Juan, Marcq, Gautier, Assmus, Mark A., Claps, Francesco, Boltri, Matteo, Burnhope, Tara, Nkwam, Nkwam, Boxall, Nicholas E., Downey, Alison P., Sukhu, Troy A., Chin, Yew-Fung, Green, James S.A., Goulao, Beatriz, Nielsen, Matthew, McGrath, John S., and Kasivisvanathan, Veeru

Published
2022
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11. Pediatric Swine Model of Methicillin-Resistant Staphylococcus aureus Sepsis-Induced Coagulopathy, Disseminated Microvascular Thrombosis, and Organ Injuries

Author

Nguyen, Trung C., Marini, Juan C., Guillory, Bobby, Valladolid-Brown, Christian, Martinez-Vargas, Marina, Subramanyam, Deepika, Cohen, Daniel, Cirlos, Sonya C., Lam, Fong, Stoll, Barbara, Didelija, Inka C., Vonderohe, Caitlin, Orellana, Renan, Saini, Arun, Pradhan, Subhashree, Bashir, Dalia, Desai, Moreshwar S., Flores, Saul, Virk, Manpreet, Tcharmtchi, Hossein, Navaei, Amir, Kaplan, Sheldon, Lamberth, Linda, Hulten, Kristina G., Scull, Brooks P., Allen, Carl E., Akcan-Arikan, Ayse, Vijayan, K. Vinod, and Cruz, Miguel A.

Published
2023
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12. Automorphisms and isomorphisms of Jha-Johnson semifields obtained from skew polynomial rings

Author

Brown, Christian, Pumpluen, Susanne, and Steele, Andrew

Subjects
Mathematics - Rings and Algebras
Abstract

We study the automorphisms of Jha-Johnson semifields obtained from an invariant irreducible twisted polynomial $f\in K[t;\sigma]$, where $K=\mathbb{F}_{q^n}$ is a finite field and $\sigma$ an automorphism of $K$ of order $n$, with a particualr emphasis on inner automorphisms and the automorphisms of Sandler and Hughes-Kleinfeld semifields. We include the automorphisms of some Knuth semifields (which do not arise from skew polynomial rings). Isomorphism between Jha-Johnson semifields are considered as well., Comment: 18 pages

Published
2017
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13. The automorphisms of Petit's algebras

Author

Brown, Christian and Pumpluen, Susanne

Subjects
Mathematics - Rings and Algebras
Abstract

Let $\sigma$ be an automorphism of a field $K$ with fixed field $F$. We study the automorphisms of nonassociative unital algebras which are canonical generalizations of the associative quotient algebras $K[t;\sigma]/fK[t;\sigma]$ obtained when the twisted polynomial $f\in K[t;\sigma]$ is invariant, and were first defined by Petit. We compute all their automorphisms if $\sigma$ commutes with all automorphisms in ${\rm Aut}_F(K)$ and $n\geq m-1$, where $n$ is the order of $\sigma$ and $m$ the degree of $f$,and obtain partial results for $n

Published
2017
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14. Solvable crossed product algebras revisited

Author

Brown, Christian and Pumpluen, Susanne

Subjects
Mathematics - Rings and Algebras, 16S35 (Primary), 16K20 (Secondary)
Abstract

For any central simple algebra over a field F which contains a maximal subfield M with non-trivial F-automorphism group G, G is solvable if and only if the algebra contains a finite chain of subalgebras which are generalized cyclic algebras over their centers (field extensions of F) satisfying certain conditions. These subalgebras are related to a normal subseries of G. A crossed product algebra F is hence solvable if and only if it can be constructed out of such a finite chain of subalgebras. This result was stated for division crossed product algebras by Petit, and overlaps with a similar result by Albert which, however, is not explicitly stated in these terms. In particular, every solvable crossed product division algebra is a generalized cyclic algebra over F.

Published
2017
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15. High-Bandwidth and Large Coupling Tolerance Graded-Index Multimode Polymer Waveguides for On-board High-Speed Optical Interconnects

Author

Chen, Jian, Bamiedakis, Nikolaos, Vasil'ev, Peter P., Edwards, Tom J., Brown, Christian T. A., Penty, Richard V., and White, Ian H.

Subjects
Computer Science - Emerging Technologies
Abstract

Optical interconnects have attracted significant research interest for use in short-reach board-level optical communication links in supercomputers and data centres. Multimode polymer waveguides in particular constitute an attractive technology for on-board optical interconnects as they provide high bandwidth, offer relaxed alignment tolerances, and can be cost-effectively integrated onto standard printed circuit boards (PCBs). However, the continuing improvements in bandwidth performance of optical sources make it important to investigate approaches to develop high bandwidth polymer waveguides. In this paper, we present dispersion studies on a graded-index (GI) waveguide in siloxane materials designed to deliver high bandwidth over a range of launch conditions. Bandwidth-length products of >70 GHzxm and ~65 GHzxm are observed using a 50/125 um multimode fibre (MMF) launch for input offsets of +/- 10 um without and with the use of a mode mixer respectively; and enhanced values of >100 GHzxm are found under a 10x microscope objective launch for input offsets of ~18 x 20 um^2. The large range of offsets is within the -1 dB alignment tolerances. A theoretical model is developed using the measured refractive index profile of the waveguide, and general agreement is found with experimental bandwidth measurements. The reported results clearly demonstrate the potential of this technology for use in high-speed board-level optical links, and indicate that data transmission of 100 Gb/s over a multimode polymer waveguide is feasible with appropriate refractive index engineering., Comment: 8 pages, 10 figures

Published
2016
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16. Dispersion Studies on Multimode Polymer Spiral Waveguides for Board-Level Optical Interconnects

Author

Chen, Jian, Bamiedakis, Nikos, Edwards, Tom J., Brown, Christian T. A., Penty, Richard V., and White, Ian H.

Subjects
Physics - Instrumentation and Detectors
Abstract

Dispersion studies are conducted on 1m long multimode polymer spiral waveguides with different refractive index profiles. Bandwidth-length products >40GHzxm are obtained from such waveguides under a 50/125 um MMF, indicating the potential of this technology., Comment: 3 pages, 2 figures, IEEE Optical Interconnects Conference (OIC), paper MD2, 2015

Published
2016
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24. Air-to-land transitions: from wingless animals and plant seeds to shuttlecocks and bio-inspired robots

Author

Ortega-Jimenez, Victor M, primary, Jusufi, Ardian, additional, Brown, Christian E, additional, Zeng, Yu, additional, Kumar, Sunny, additional, Siddall, Robert, additional, Kim, Baekgyeom, additional, Challita, Elio J, additional, Pavlik, Zoe, additional, Priess, Meredith, additional, Umhofer, Thomas, additional, Koh, Je-Sung, additional, Socha, John J, additional, Dudley, Robert, additional, and Bhamla, M Saad, additional

Published
2023
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28. The State and the Supernatural: Support for Prosocial Behavior

Author

Brown, Christian and Eff, E. Anthon

Subjects
Other Economics, Other Religion, Social and Cultural Anthropology, Galton’s problem, religion, prosocial behavior, movable property, human competition, cultural transmission, Standard Cross-Cultural Sample
Abstract

Using the Standard Cross-Cultural Sample, Roes and Raymond (2003) find that large societies are more likely to be located in resource-rich environments, engage in warfare, and hold beliefs in gods actively supporting human morality (“moralizing gods”). We revisit the Roes and Raymond study, using the methods presented in a series of papers by Dow and Eff. Our findings suggest that moralizing gods are less likely to be found in resource-rich environments or amongst societies frequently engaged in external warfare. We find that cultural transmission over geographic space is the most significant force in conditioning belief in moralizing gods; that moralizing gods are more likely to be found in pastoral societies; and that the relationship between society size and moralizing gods is non-linear, with both very large and very small societies less likely to have moralizing gods. We explain this non-linearity by arguing that the functions of moralizing gods can also be performed by the state, and we also argue that moralizing gods play an important role in stabilizing property rights.

Published
2010

34. Assessing red spruce (Picea rubens Sarg.) restoration potential under current and future predicted climate change in Virginia.

Author

Brown, Christian H. and Griscom, Heather P.

Subjects
*SPRUCE, *ECOLOGICAL niche, *ECOLOGICAL models, *CLIMATE change
Abstract

Global climate change threatens many species across the planet. High‐elevation species, such as red spruce (Picea rubens), face significant and immediate threats from climate change. Red spruce has faced anthropogenic disturbances for over a century and is only recently beginning to recover across its range. Ecological niche modeling has become a common method of identifying the suitable habitat of a species, providing vital information to land managers carrying out restoration efforts. In this study, ecological niche models were used in a novel way, predicting distribution and habitat suitability separately and simultaneously to determine the spatial extent to which red spruce forests can be restored. In addition to models, surveys were conducted to elucidate the current regeneration trends of red spruce. Furthermore, climate projections were used to determine how restoration potential may change over the course of the twenty‐first century. Comparisons between distribution and habitat suitability models indicate that there is additional habitat available for red spruce expansion. Regeneration surveys show that there is positive regeneration both within and beyond red spruce canopies, validating model comparisons. Climate change projections indicate total elimination of suitable habitat in Virginia by 2100. However, these projections likely predict increased competition for red spruce from low elevation competitors as opposed to physiological limitations imposed by climate change. It is therefore prudent to protect established populations and encourage further regeneration within and beyond current red spruce stands in anticipation of future ecological shifts. [ABSTRACT FROM AUTHOR]

Published
2023
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36. Correction: Obesity and critical care nutrition: current practice gaps and directions for future research

Author

Dickerson, Roland N., Andromalos, Laura, Brown, Christian, Correia, Maria Isabel T.D., Pritts, Wanda, Ridley, Emma J., Robinson, Katie N., Rosenthal, Martin D., and van Zanten, Arthur R.H.

Subjects
Life Science, Critical Care and Intensive Care Medicine, Nutritional Biology
Abstract

Following publication of the original article [1], the authors reported an error in the Competing Interests section. The Competing Interests section currently reads: Competing Interests The authors declare no competing interests. The Competing Interests section should read: Competing Interests Katie N. Robinson works and owns stock in Abbott Nutrition. The Competing Interests section has been updated above and the original article [1] has been corrected.

Published
2023

37. Supplementary Data from Identification of Rigosertib for the Treatment of Recessive Dystrophic Epidermolysis Bullosa–Associated Squamous Cell Carcinoma

Author

Atanasova, Velina S., primary, Pourreyron, Celine, primary, Farshchian, Mehdi, primary, Lawler, Michael, primary, Brown, Christian A., primary, Watt, Stephen A., primary, Wright, Sheila, primary, Warkala, Michael, primary, Guttmann-Gruber, Christina, primary, Hofbauer, Josefina Piñón, primary, Fuentes, Ignacia, primary, Prisco, Marco, primary, Rashidghamat, Elham, primary, Has, Cristina, primary, Salas-Alanis, Julio C., primary, Palisson, Francis, primary, Hovnanian, Alain, primary, McGrath, John A., primary, Mellerio, Jemima E., primary, Bauer, Johann W., primary, and South, Andrew P., primary

Published
2023
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39. Nd-doped crystal waveguide lasers and amplifiers

Author

Brown, Christian Thomas Alcuin and Tropper, Anne

Subjects
535, QC Physics, TK Electrical engineering. Electronics Nuclear engineering
Abstract

This thesis presents the results of investigations into waveguide lasers and optical amplifiers fabricated in Nd-doped crystals. Laser operation of Nd3+ doped Ti:LiNbO3 around 900nm is reported. A threshold power of 26mW was obtained when the device was pumped with a Ti:Al2O3 laser operating around 814nm. The wavelength of the waveguide fundamental mode cut-off was altered by manipulation of the device fabrication parameters to induce higher propagation losses at the parasitic laser wavelength of 1.084µm and thus enhance lasing behaviour around 900nm. A 1.2W diode-pumped, Nd:Y3Al5O12 (Nd:YAG) waveguide optical amplifier has been demonstrated with a simple double pass geometry. Small signal gains as high as 28.4dB were observed along with extracted power efficiencies of up to 36%. Deviation from ideal performance is explained by reference to intense pumping effects and pump/signal overlap in the device. The coupling of diode-bars into planar waveguides for high power operation has been analysed. Using a lens array to couple the diode output into an Nd:YAG planar waveguide, an extremely compact, end pumped, device was constructed which had a slope efficiency of 40% with respect to incident pump power and a maximum output power of 1.5W for 6W of diode power. Fibre lens and proximity coupling scheme designs have also been examined. A Ti:Al2O3 face pumped LPE waveguide laser has been demonstrated. Nd:YAG on YAG, Nd:Gd3Ga5O12 on YAG and Nd:YAG on glass waveguides fabricated by thermal bonding have been studied. These structures had numerical apertures of 0.06, 0.74 and 0.82 respectively. The propagation losses, obtained from the laser performance, were found to be 0.7B/cm, 0.4dB/cm and 0.7dB/cm respectively.

Published
1997

41. Evaluating Home-Based Health Coaching from Community Health Representatives for Navajo Adults with Type 2 Diabetes

Author

Shin, Sonya, primary, Nelson, Katrina, additional, Trevisi, Letizia, additional, Orav, Endel John, additional, Franz, Calvin, additional, Atwood, Sidney, additional, Curley, Cameron, additional, Muskett, Olivia, additional, King, Caroline, additional, Brown, Christian, additional, Singer, Judy, additional, Kahn, Tina, additional, Kahn, Alfred, additional, Talk, Bobby, additional, Mosbarger, William, additional, Clark, clarina, additional, Smith, Delphina, additional, Salt, Shine, additional, Smith, Casey, additional, Shirley, Lenora, additional, and Begay, Mae-Gilene, additional

Published
2020
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42. Clinical outcomes of anterior prostate cancers treated with robotic assisted radical prostatectomy

Author

Saghir, Reyan, primary, Russell, Beth, additional, Kum, Francesca, additional, Darwish, Raef, additional, Deane, Jude, additional, Allen, Christopher, additional, Rizwi, Hira, additional, Saghir, Noman, additional, Mayor, Nikhil, additional, Cathcart, Paul, additional, Dasgupta, Prokar, additional, Popert, Rick, additional, Brown, Christian, additional, and Challacombe, Ben, additional

Published
2022
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46. Irreducible skew polynomials over domains

Author

Brown, Christian and Pumpluen, Susanne

Subjects
16S36, Rings and Algebras (math.RA), FOS: Mathematics, General Materials Science, Mathematics - Rings and Algebras
Abstract

Let $S$ be a domain and $R=S[t;\sigma,\delta]$ a skew polynomial ring, where $\sigma$ is an injective endomorphism of $S$ and $\delta$ a left $\sigma$ -derivation. We give criteria for skew polynomials $f\in R$ of degree less or equal to four to be irreducible. We apply them to low degree polynomials in quantized Weyl algebras and the quantum planes. We also consider $f(t)=t^m-a\in R$., Comment: Updated slightly rewritten version of the previously deposited one

Published
2021

48. Hydrolysis of Metal Ions

Author

Paul L. Brown, Christian Ekberg and Paul L. Brown, Christian Ekberg

Published
2016

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