2,779 results on '"Martin, Richard M"'
Search Results
52. Electronic Structure of Self-Assembled Quantum Dots: Comparison Between Density Functional Theory and Diffusion Quantum Monte Carlo
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Shumway, J., primary, Fonseca, L. R. C., additional, Leburton, J.-P., additional, Martin, Richard M., additional, and Ceperley, D. M., additional
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- 2021
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53. Electronic Properties and Spin Polarization in Coupled Quantum Dots
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Nagaraja, Satyadev, primary, Leburton, Jean-Pierre, additional, and Martin, Richard M., additional
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- 2021
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54. Shell-Filling Effects and Coulomb Degeneracy in Planar Quantum Dot Structures
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Nagaraja, Satyadev, primary, Matagne, Philippe, additional, Thean, Voon-Yew, additional, Leburton, Jean-Pierre, additional, Kim, Yong-Hoon, additional, and Martin, Richard M., additional
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- 2021
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55. Electronic Properties and Mid-Infrared Transitions in Self-Assembled Quantum Dots
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Leburton, Jean-Pierre, primary, Fonseca, Leornado R. C., additional, Shumway, John, additional, Ceperley, David, additional, and Martin, Richard M., additional
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- 2021
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56. 2D Limit of Exchange–Correlation Density Energy Functional Approximation
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Kim, Yong-Hoon, primary, Lee, In-Ho, additional, Nagaraja, Satyadev, additional, Leburton, Jean-Pierre, additional, Hood, Randolph Q., additional, and Martin, Richard M., additional
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- 2021
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57. Capacitive Energy of Quantum Dots with Hydrogenic Impurity
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Lee, In-Ho, primary, Ahn, Kang-Hun, additional, Kim, Yong-Hoon, additional, Martin, Richard M., additional, and Leburton, Jean-Pierre, additional
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- 2021
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58. Obesity, metabolic factors and risk of different histological types of lung cancer: A Mendelian randomization study
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Carreras-Torres, Robert, Johansson, Mattias, Haycock, Philip C, Wade, Kaitlin H, Relton, Caroline L, Martin, Richard M, Smith, George Davey, Albanes, Demetrius, Aldrich, Melinda C, Andrew, Angeline, Arnold, Susanne M, Bickeböller, Heike, Bojesen, Stig E, Brunnström, Hans, Manjer, Jonas, Brüske, Irene, Caporaso, Neil E, Chen, Chu, Christiani, David C, Christian, W Jay, Doherty, Jennifer A, Duell, Eric J, Field, John K, Davies, Michael PA, Marcus, Michael W, Goodman, Gary E, Grankvist, Kjell, Haugen, Aage, Hong, Yun-Chul, Kiemeney, Lambertus A, van der Heijden, Erik HFM, Kraft, Peter, Johansson, Mikael B, Lam, Stephen, Landi, Maria Teresa, Lazarus, Philip, Le Marchand, Loïc, Liu, Geoffrey, Melander, Olle, Park, Sungshim L, Rennert, Gad, Risch, Angela, Haura, Eric B, Scelo, Ghislaine, Zaridze, David, Mukeriya, Anush, Savić, Milan, Lissowska, Jolanta, Swiatkowska, Beata, Janout, Vladimir, Holcatova, Ivana, Mates, Dana, Schabath, Matthew B, Shen, Hongbing, Tardon, Adonina, Teare, M Dawn, Woll, Penella, Tsao, Ming-Sound, Wu, Xifeng, Yuan, Jian-Min, Hung, Rayjean J, Amos, Christopher I, McKay, James, and Brennan, Paul
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Epidemiology ,Biomedical and Clinical Sciences ,Health Sciences ,Oncology and Carcinogenesis ,Genetics ,Lung ,Nutrition ,Tobacco Smoke and Health ,Prevention ,Cancer ,Tobacco ,Obesity ,Clinical Research ,Lung Cancer ,Aetiology ,2.1 Biological and endogenous factors ,Body Mass Index ,Fasting ,Humans ,Insulin ,Insulin Resistance ,Likelihood Functions ,Lipids ,Lung Neoplasms ,Mendelian Randomization Analysis ,Phenotype ,Polymorphism ,Single Nucleotide ,Risk Factors ,General Science & Technology - Abstract
BackgroundAssessing the relationship between lung cancer and metabolic conditions is challenging because of the confounding effect of tobacco. Mendelian randomization (MR), or the use of genetic instrumental variables to assess causality, may help to identify the metabolic drivers of lung cancer.Methods and findingsWe identified genetic instruments for potential metabolic risk factors and evaluated these in relation to risk using 29,266 lung cancer cases (including 11,273 adenocarcinomas, 7,426 squamous cell and 2,664 small cell cases) and 56,450 controls. The MR risk analysis suggested a causal effect of body mass index (BMI) on lung cancer risk for two of the three major histological subtypes, with evidence of a risk increase for squamous cell carcinoma (odds ratio (OR) [95% confidence interval (CI)] = 1.20 [1.01-1.43] and for small cell lung cancer (OR [95%CI] = 1.52 [1.15-2.00]) for each standard deviation (SD) increase in BMI [4.6 kg/m2]), but not for adenocarcinoma (OR [95%CI] = 0.93 [0.79-1.08]) (Pheterogeneity = 4.3x10-3). Additional analysis using a genetic instrument for BMI showed that each SD increase in BMI increased cigarette consumption by 1.27 cigarettes per day (P = 2.1x10-3), providing novel evidence that a genetic susceptibility to obesity influences smoking patterns. There was also evidence that low-density lipoprotein cholesterol was inversely associated with lung cancer overall risk (OR [95%CI] = 0.90 [0.84-0.97] per SD of 38 mg/dl), while fasting insulin was positively associated (OR [95%CI] = 1.63 [1.25-2.13] per SD of 44.4 pmol/l). Sensitivity analyses including a weighted-median approach and MR-Egger test did not detect other pleiotropic effects biasing the main results.ConclusionsOur results are consistent with a causal role of fasting insulin and low-density lipoprotein cholesterol in lung cancer etiology, as well as for BMI in squamous cell and small cell carcinoma. The latter relation may be mediated by a previously unrecognized effect of obesity on smoking behavior.
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- 2017
59. Using a Modified Delphi Approach to Gain Consensus on Relevant Comparators in a Cost-Effectiveness Model: Application to Prostate Cancer Screening
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Keeney, Edna, Thom, Howard, Turner, Emma, Martin, Richard M., and Sanghera, Sabina
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- 2021
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60. The Use of Primary Care Big Data in Understanding the Pharmacoepidemiology of COVID-19: A Consensus Statement From the COVID-19 Primary Care Database Consortium
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Dambha-Miller, Hajira, Griffin, Simon J., Young, Duncan, Watkinson, Peter, Tan, Pui San, Clift, Ashley K., Payne, Rupert A., Coupland, Carol, Hopewell, Jemma C., Mant, Jonathan, Martin, Richard M., and Hippisley-Cox, Julia
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Medical research -- Methods ,Medicine, Experimental -- Methods ,Big data -- Usage -- Health aspects ,Medical records -- Usage ,Primary health care ,Health ,Science and technology - Abstract
The use of big data containing millions of primary care medical records provides an opportunity for rapid research to help inform patient care and policy decisions during the first and subsequent waves of the coronavirus disease 2019 (COVID-19) pandemic. Routinely collected primary care data have previously been used for national pandemic surveillance, quantifying associations between exposures and outcomes, identifying high risk populations, and examining the effects of interventions at scale, but there is no consensus on how to effectively conduct or report these data for COVID-19 research. A COVID-19 primary care database consortium was established in April 2020 and its researchers have ongoing COVID-19 projects in overlapping data sets with over 40 million primary care records in the United Kingdom that are variously linked to public health, secondary care, and vital status records. This consensus agreement is aimed at facilitating transparency and rigor in methodological approaches, and consistency in defining and reporting cases, exposures, confounders, stratification variables, and outcomes in relation to the pharmacoepidemiology of COVID-19. This will facilitate comparison, validation, and meta-analyses of research during and after the pandemic. Key words: big data; coronavirus; epidemiology; primary health care, INTRODUCTION Primary care big data refers to routinely collected anonymized general practitioner (GP) electronic health records that form large and complex longitudinal databases, often with hundreds of variables at an [...]
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- 2021
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61. Trans-ancestry genome-wide association meta-analysis of prostate cancer identifies new susceptibility loci and informs genetic risk prediction
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Conti, David V., Darst, Burcu F., Moss, Lilit C., Saunders, Edward J., Sheng, Xin, Chou, Alisha, Schumacher, Fredrick R., Olama, Ali Amin Al, Benlloch, Sara, Dadaev, Tokhir, Brook, Mark N., Sahimi, Ali, Hoffmann, Thomas J., Takahashi, Atushi, Matsuda, Koichi, Momozawa, Yukihide, Fujita, Masashi, Muir, Kenneth, Lophatananon, Artitaya, Wan, Peggy, Le Marchand, Loic, Wilkens, Lynne R., Stevens, Victoria L., Gapstur, Susan M., Carter, Brian D., Schleutker, Johanna, Tammela, Teuvo L. J., Sipeky, Csilla, Auvinen, Anssi, Giles, Graham G., Southey, Melissa C., MacInnis, Robert J., Cybulski, Cezary, Wokołorczyk, Dominika, Lubiński, Jan, Neal, David E., Donovan, Jenny L., Hamdy, Freddie C., Martin, Richard M., Nordestgaard, Børge G., Nielsen, Sune F., Weischer, Maren, Bojesen, Stig E., Røder, Martin Andreas, Iversen, Peter, Batra, Jyotsna, Chambers, Suzanne, Moya, Leire, Horvath, Lisa, Clements, Judith A., Tilley, Wayne, Risbridger, Gail P., Gronberg, Henrik, Aly, Markus, Szulkin, Robert, Eklund, Martin, Nordström, Tobias, Pashayan, Nora, Dunning, Alison M., Ghoussaini, Maya, Travis, Ruth C., Key, Tim J., Riboli, Elio, Park, Jong Y., Sellers, Thomas A., Lin, Hui-Yi, Albanes, Demetrius, Weinstein, Stephanie J., Mucci, Lorelei A., Giovannucci, Edward, Lindstrom, Sara, Kraft, Peter, Hunter, David J., Penney, Kathryn L., Turman, Constance, Tangen, Catherine M., Goodman, Phyllis J., Thompson, Jr., Ian M., Hamilton, Robert J., Fleshner, Neil E., Finelli, Antonio, Parent, Marie-Élise, Stanford, Janet L., Ostrander, Elaine A., Geybels, Milan S., Koutros, Stella, Freeman, Laura E. Beane, Stampfer, Meir, Wolk, Alicja, Håkansson, Niclas, Andriole, Gerald L., Hoover, Robert N., Machiela, Mitchell J., Sørensen, Karina Dalsgaard, Borre, Michael, Blot, William J., Zheng, Wei, Yeboah, Edward D., Mensah, James E., Lu, Yong-Jie, Zhang, Hong-Wei, Feng, Ninghan, Mao, Xueying, Wu, Yudong, Zhao, Shan-Chao, Sun, Zan, Thibodeau, Stephen N., McDonnell, Shannon K., Schaid, Daniel J., West, Catharine M. L., Burnet, Neil, Barnett, Gill, Maier, Christiane, Schnoeller, Thomas, Luedeke, Manuel, Kibel, Adam S., Drake, Bettina F., Cussenot, Olivier, Cancel-Tassin, Géraldine, Menegaux, Florence, Truong, Thérèse, Koudou, Yves Akoli, John, Esther M., Grindedal, Eli Marie, Maehle, Lovise, Khaw, Kay-Tee, Ingles, Sue A., Stern, Mariana C., Vega, Ana, Gómez-Caamaño, Antonio, Fachal, Laura, Rosenstein, Barry S., Kerns, Sarah L., Ostrer, Harry, Teixeira, Manuel R., Paulo, Paula, Brandão, Andreia, Watya, Stephen, Lubwama, Alexander, Bensen, Jeannette T., Fontham, Elizabeth T. H., Mohler, James, Taylor, Jack A., Kogevinas, Manolis, Llorca, Javier, Castaño-Vinyals, Gemma, Cannon-Albright, Lisa, Teerlink, Craig C., Huff, Chad D., Strom, Sara S., Multigner, Luc, Blanchet, Pascal, Brureau, Laurent, Kaneva, Radka, Slavov, Chavdar, Mitev, Vanio, Leach, Robin J., Weaver, Brandi, Brenner, Hermann, Cuk, Katarina, Holleczek, Bernd, Saum, Kai-Uwe, Klein, Eric A., Hsing, Ann W., Kittles, Rick A., Murphy, Adam B., Logothetis, Christopher J., Kim, Jeri, Neuhausen, Susan L., Steele, Linda, Ding, Yuan Chun, Isaacs, William B., Nemesure, Barbara, Hennis, Anselm J. M., Carpten, John, Pandha, Hardev, Michael, Agnieszka, De Ruyck, Kim, De Meerleer, Gert, Ost, Piet, Xu, Jianfeng, Razack, Azad, Lim, Jasmine, Teo, Soo-Hwang, Newcomb, Lisa F., Lin, Daniel W., Fowke, Jay H., Neslund-Dudas, Christine, Rybicki, Benjamin A., Gamulin, Marija, Lessel, Davor, Kulis, Tomislav, Usmani, Nawaid, Singhal, Sandeep, Parliament, Matthew, Claessens, Frank, Joniau, Steven, Van den Broeck, Thomas, Gago-Dominguez, Manuela, Castelao, Jose Esteban, Martinez, Maria Elena, Larkin, Samantha, Townsend, Paul A., Aukim-Hastie, Claire, Bush, William S., Aldrich, Melinda C., Crawford, Dana C., Srivastava, Shiv, Cullen, Jennifer C., Petrovics, Gyorgy, Casey, Graham, Roobol, Monique J., Jenster, Guido, van Schaik, Ron H. N., Hu, Jennifer J., Sanderson, Maureen, Varma, Rohit, McKean-Cowdin, Roberta, Torres, Mina, Mancuso, Nicholas, Berndt, Sonja I., Van Den Eeden, Stephen K., Easton, Douglas F., Chanock, Stephen J., Cook, Michael B., Wiklund, Fredrik, Nakagawa, Hidewaki, Witte, John S., Eeles, Rosalind A., Kote-Jarai, Zsofia, and Haiman, Christopher A.
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- 2021
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62. Prostate-Specific Antigen Screening and 15-Year Prostate Cancer Mortality: A Secondary Analysis of the CAP Randomized Clinical Trial.
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Martin, Richard M., Turner, Emma L., Young, Grace J., Metcalfe, Chris, Walsh, Eleanor I., Lane, J. Athene, Sterne, Jonathan A. C., Noble, Sian, Holding, Peter, Ben-Shlomo, Yoav, Williams, Naomi J., Pashayan, Nora, Bui, Mai Ngoc, Albertsen, Peter C., Seibert, Tyler M., Zietman, Anthony L., Oxley, Jon, Adolfsson, Jan, Mason, Malcolm D., and Davey Smith, George
- Abstract
This secondary analysis of a randomized clinical trial assesses whether screening for prostate-specific antigen reduces prostate cancer mortality at 15-year follow-up. Key Points: Question: In men aged 50 to 69 years, does a single invitation for a prostate-specific antigen (PSA) screening test reduce prostate cancer mortality at 15-year follow-up compared with no invitation for testing? Findings: In this secondary analysis of a randomized clinical trial of 415 357 men aged 50 to 69 years randomized to a single invitation for PSA screening (n = 195 912) or a control group without PSA screening (n = 219 445) and followed up for a median of 15 years, risk of death from prostate cancer was lower in the group invited to screening (0.69% vs 0.78%; mean difference, 0.09%) compared with the control group. Meaning: Compared with no invitation for routine PSA testing, a single invitation for a PSA screening test reduced prostate cancer mortality at a median follow-up of 15 years, but the absolute mortality benefit was small. Importance: The Cluster Randomized Trial of PSA Testing for Prostate Cancer (CAP) reported no effect of prostate-specific antigen (PSA) screening on prostate cancer mortality at a median 10-year follow-up (primary outcome), but the long-term effects of PSA screening on prostate cancer mortality remain unclear. Objective: To evaluate the effect of a single invitation for PSA screening on prostate cancer–specific mortality at a median 15-year follow-up compared with no invitation for screening. Design, Setting, and Participants: This secondary analysis of the CAP randomized clinical trial included men aged 50 to 69 years identified at 573 primary care practices in England and Wales. Primary care practices were randomized between September 25, 2001, and August 24, 2007, and men were enrolled between January 8, 2002, and January 20, 2009. Follow-up was completed on March 31, 2021. Intervention: Men received a single invitation for a PSA screening test with subsequent diagnostic tests if the PSA level was 3.0 ng/mL or higher. The control group received standard practice (no invitation). Main Outcomes and Measures: The primary outcome was reported previously. Of 8 prespecified secondary outcomes, results of 4 were reported previously. The 4 remaining prespecified secondary outcomes at 15-year follow-up were prostate cancer–specific mortality, all-cause mortality, and prostate cancer stage and Gleason grade at diagnosis. Results: Of 415 357 eligible men (mean [SD] age, 59.0 [5.6] years), 98% were included in these analyses. Overall, 12 013 and 12 958 men with a prostate cancer diagnosis were in the intervention and control groups, respectively (15-year cumulative risk, 7.08% [95% CI, 6.95%-7.21%] and 6.94% [95% CI, 6.82%-7.06%], respectively). At a median 15-year follow-up, 1199 men in the intervention group (0.69% [95% CI, 0.65%-0.73%]) and 1451 men in the control group (0.78% [95% CI, 0.73%-0.82%]) died of prostate cancer (rate ratio [RR], 0.92 [95% CI, 0.85-0.99]; P =.03). Compared with the control, the PSA screening intervention increased detection of low-grade (Gleason score [GS] ≤6: 2.2% vs 1.6%; P <.001) and localized (T1/T2: 3.6% vs 3.1%; P <.001) disease but not intermediate (GS of 7), high-grade (GS ≥8), locally advanced (T3), or distally advanced (T4/N1/M1) tumors. There were 45 084 all-cause deaths in the intervention group (23.2% [95% CI, 23.0%-23.4%]) and 50 336 deaths in the control group (23.3% [95% CI, 23.1%-23.5%]) (RR, 0.97 [95% CI, 0.94-1.01]; P =.11). Eight of the prostate cancer deaths in the intervention group (0.7%) and 7 deaths in the control group (0.5%) were related to a diagnostic biopsy or prostate cancer treatment. Conclusions and Relevance: In this secondary analysis of a randomized clinical trial, a single invitation for PSA screening compared with standard practice without routine screening reduced prostate cancer deaths at a median follow-up of 15 years. However, the absolute reduction in deaths was small. Trial Registration: isrctn.org Identifier: ISRCTN92187251 [ABSTRACT FROM AUTHOR]
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- 2024
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63. Mendelian randomisation for nutritional psychiatry
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Carnegie, Rebecca, Zheng, Jie, Sallis, Hannah M, Jones, Hannah J, Wade, Kaitlin H, Evans, Jonathan, Zammit, Stan, Munafò, Marcus R, and Martin, Richard M
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- 2020
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64. The causal relevance of body mass index in different histological types of lung cancer: A Mendelian randomization study.
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Carreras-Torres, Robert, Haycock, Philip C, Relton, Caroline L, Martin, Richard M, Smith, George Davey, Kraft, Peter, Gao, Chi, Tworoger, Shelley, Le Marchand, Loïc, Wilkens, Lynne R, Park, Sungshim L, Haiman, Christopher, Field, John K, Davies, Michael, Marcus, Michael, Liu, Geoffrey, Caporaso, Neil E, Christiani, David C, Wei, Yongyue, Chen, Chu, Doherty, Jennifer A, Severi, Gianluca, Goodman, Gary E, Hung, Rayjean J, Amos, Christopher I, McKay, James, Johansson, Mattias, and Brennan, Paul
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Humans ,Lung Neoplasms ,Body Mass Index ,Risk Factors ,Case-Control Studies ,Smoking ,Female ,Male ,Mendelian Randomization Analysis - Abstract
Body mass index (BMI) is inversely associated with lung cancer risk in observational studies, even though it increases the risk of several other cancers, which could indicate confounding by tobacco smoking or reverse causality. We used the two-sample Mendelian randomization (MR) approach to circumvent these limitations of observational epidemiology by constructing a genetic instrument for BMI, based on results from the GIANT consortium, which was evaluated in relation to lung cancer risk using GWAS results on 16,572 lung cancer cases and 21,480 controls. Results were stratified by histological subtype, smoking status and sex. An increase of one standard deviation (SD) in BMI (4.65 Kg/m(2)) raised the risk for lung cancer overall (OR = 1.13; P = 0.10). This was driven by associations with squamous cell (SQ) carcinoma (OR = 1.45; P = 1.2 × 10(-3)) and small cell (SC) carcinoma (OR = 1.81; P = 0.01). An inverse trend was seen for adenocarcinoma (AD) (OR = 0.82; P = 0.06). In stratified analyses, a 1 SD increase in BMI was inversely associated with overall lung cancer in never smokers (OR = 0.50; P = 0.02). These results indicate that higher BMI may increase the risk of certain types of lung cancer, in particular SQ and SC carcinoma.
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- 2016
65. A Meta-analysis of Individual Participant Data Reveals an Association between Circulating Levels of IGF-I and Prostate Cancer Risk
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Travis, Ruth C, Appleby, Paul N, Martin, Richard M, Holly, Jeff MP, Albanes, Demetrius, Black, Amanda, Bueno-de-Mesquita, HB As, Chan, June M, Chen, Chu, Chirlaque, Maria-Dolores, Cook, Michael B, Deschasaux, Mélanie, Donovan, Jenny L, Ferrucci, Luigi, Galan, Pilar, Giles, Graham G, Giovannucci, Edward L, Gunter, Marc J, Habel, Laurel A, Hamdy, Freddie C, Helzlsouer, Kathy J, Hercberg, Serge, Hoover, Robert N, Janssen, Joseph AMJL, Kaaks, Rudolf, Kubo, Tatsuhiko, Le Marchand, Loic, Metter, E Jeffrey, Mikami, Kazuya, Morris, Joan K, Neal, David E, Neuhouser, Marian L, Ozasa, Kotaro, Palli, Domenico, Platz, Elizabeth A, Pollak, Michael, Price, Alison J, Roobol, Monique J, Schaefer, Catherine, Schenk, Jeannette M, Severi, Gianluca, Stampfer, Meir J, Stattin, Pär, Tamakoshi, Akiko, Tangen, Catherine M, Touvier, Mathilde, Wald, Nicholas J, Weiss, Noel S, Ziegler, Regina G, Key, Timothy J, and Allen, Naomi E
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Biomedical and Clinical Sciences ,Clinical Sciences ,Oncology and Carcinogenesis ,Aging ,Prostate Cancer ,Cancer ,Urologic Diseases ,Aged ,Humans ,Insulin-Like Growth Factor I ,Male ,Middle Aged ,Prostatic Neoplasms ,Risk Factors ,Oncology & Carcinogenesis ,Biochemistry and cell biology ,Oncology and carcinogenesis - Abstract
The role of insulin-like growth factors (IGF) in prostate cancer development is not fully understood. To investigate the association between circulating concentrations of IGFs (IGF-I, IGF-II, IGFBP-1, IGFBP-2, and IGFBP-3) and prostate cancer risk, we pooled individual participant data from 17 prospective and two cross-sectional studies, including up to 10,554 prostate cancer cases and 13,618 control participants. Conditional logistic regression was used to estimate the ORs for prostate cancer based on the study-specific fifth of each analyte. Overall, IGF-I, IGF-II, IGFBP-2, and IGFBP-3 concentrations were positively associated with prostate cancer risk (Ptrend all ≤ 0.005), and IGFBP-1 was inversely associated weakly with risk (Ptrend = 0.05). However, heterogeneity between the prospective and cross-sectional studies was evident (Pheterogeneity = 0.03), unless the analyses were restricted to prospective studies (with the exception of IGF-II, Pheterogeneity = 0.02). For prospective studies, the OR for men in the highest versus the lowest fifth of each analyte was 1.29 (95% confidence interval, 1.16-1.43) for IGF-I, 0.81 (0.68-0.96) for IGFBP-1, and 1.25 (1.12-1.40) for IGFBP-3. These associations did not differ significantly by time-to-diagnosis or tumor stage or grade. After mutual adjustment for each of the other analytes, only IGF-I remained associated with risk. Our collaborative study represents the largest pooled analysis of the relationship between prostate cancer risk and circulating concentrations of IGF-I, providing strong evidence that IGF-I is highly likely to be involved in prostate cancer development. Cancer Res; 76(8); 2288-300. ©2016 AACR.
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- 2016
66. Examination of potential novel biochemical factors in relation to prostate cancer incidence and mortality in UK Biobank
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Perez-Cornago, Aurora, Fensom, Georgina K., Andrews, Colm, Watts, Eleanor L., Allen, Naomi E., Martin, Richard M., Van Hemelrijck, Mieke, Key, Timothy J., and Travis, Ruth C.
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- 2020
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67. Carotenoids, retinol, tocopherols, and prostate cancer risk: pooled analysis of 15 studies 1–3
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Key, Timothy J, Appleby, Paul N, Travis, Ruth C, Albanes, Demetrius, Alberg, Anthony J, Barricarte, Aurelio, Black, Amanda, Boeing, Heiner, Bueno-de-Mesquita, H Bas, Chan, June M, Chen, Chu, Cook, Michael B, Donovan, Jenny L, Galan, Pilar, Gilbert, Rebecca, Giles, Graham G, Giovannucci, Edward, Goodman, Gary E, Goodman, Phyllis J, Gunter, Marc J, Hamdy, Freddie C, Heliövaara, Markku, Helzlsouer, Kathy J, Henderson, Brian E, Hercberg, Serge, Hoffman-Bolton, Judy, Hoover, Robert N, Johansson, Mattias, Khaw, Kay-Tee, King, Irena B, Knekt, Paul, Kolonel, Laurence N, Le Marchand, Loic, Männistö, Satu, Martin, Richard M, Meyer, Haakon E, Mondul, Alison M, Moy, Kristin A, Neal, David E, Neuhouser, Marian L, Palli, Domenico, Platz, Elizabeth A, Pouchieu, Camille, Rissanen, Harri, Schenk, Jeannette M, Severi, Gianluca, Stampfer, Meir J, Tjønneland, Anne, Touvier, Mathilde, Trichopoulou, Antonia, Weinstein, Stephanie J, Ziegler, Regina G, Zhou, Cindy Ke, Allen, Naomi E, Biomarkers, Endogenous Hormones Nutritional, and Group, Prostate Cancer Collaborative
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Biomedical and Clinical Sciences ,Oncology and Carcinogenesis ,Prevention ,Urologic Diseases ,Nutrition ,Prostate Cancer ,Cancer ,Aging ,Clinical Research ,Adult ,Biomarkers ,Carotenoids ,Case-Control Studies ,Cohort Studies ,Cross-Sectional Studies ,Humans ,Lycopene ,Male ,Meta-Analysis as Topic ,Middle Aged ,Neoplasm Grading ,Neoplasm Staging ,Observational Studies as Topic ,Prospective Studies ,Prostate ,Prostatic Neoplasms ,Risk Factors ,Vitamin A ,alpha-Tocopherol ,prostate cancer ,carotenoids ,retinol ,tocopherols ,vitamin E ,vitamin A ,pooled analysis ,nested case-control study ,biomarkers ,Endogenous Hormones Nutritional Biomarkers Prostate Cancer Collaborative Group ,Engineering ,Medical and Health Sciences ,Nutrition & Dietetics ,Clinical sciences ,Nutrition and dietetics - Abstract
BackgroundIndividual studies have suggested that circulating carotenoids, retinol, or tocopherols may be associated with prostate cancer risk, but the studies have not been large enough to provide precise estimates of associations, particularly by stage and grade of disease.ObjectiveThe objective of this study was to conduct a pooled analysis of the associations of the concentrations of 7 carotenoids, retinol, α-tocopherol, and γ-tocopherol with risk of prostate cancer and to describe whether any associations differ by stage or grade of the disease or other factors.DesignPrincipal investigators of prospective studies provided individual participant data for prostate cancer cases and controls. Risk by study-specific fifths of each biomarker was estimated by using multivariable-adjusted conditional logistic regression in matched case-control sets.ResultsData were available for up to 11,239 cases (including 1654 advanced stage and 1741 aggressive) and 18,541 controls from 15 studies. Lycopene was not associated with overall risk of prostate cancer, but there was statistically significant heterogeneity by stage of disease, and the OR for aggressive disease for the highest compared with the lowest fifth of lycopene was 0.65 (95% CI: 0.46, 0.91; P-trend = 0.032). No other carotenoid was significantly associated with overall risk of prostate cancer or with risk of advanced-stage or aggressive disease. For retinol, the OR for the highest compared with the lowest fifth was 1.13 (95% CI: 1.04, 1.22; P-trend = 0.015). For α-tocopherol, the OR for the highest compared with the lowest fifth was 0.86 (95% CI: 0.78, 0.94; P-trend < 0.001), with significant heterogeneity by stage of disease; the OR for aggressive prostate cancer was 0.74 (95% CI: 0.59, 0.92; P-trend = 0.001). γ-Tocopherol was not associated with risk.ConclusionsOverall prostate cancer risk was positively associated with retinol and inversely associated with α-tocopherol, and risk of aggressive prostate cancer was inversely associated with lycopene and α-tocopherol. Whether these associations reflect causal relations is unclear.
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- 2015
68. Mendelian randomization does not support serum calcium in prostate cancer risk
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Yarmolinsky, James, Berryman, Katie, Langdon, Ryan, Bonilla, Carolina, Smith, George Davey, Martin, Richard M., and Lewis, Sarah J.
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- 2018
69. Circulating adiponectin and leptin and risk of overall and aggressive prostate cancer: a systematic review and meta-analysis
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Burton, Anya J., Gilbert, Rebecca, Tilling, Kate, Langdon, Ryan, Donovan, Jenny L., Holly, Jeff M. P., and Martin, Richard M.
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- 2021
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70. Transcriptome-wide Mendelian randomization study prioritising novel tissue-dependent genes for glioma susceptibility
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Robinson, Jamie W., Martin, Richard M., Tsavachidis, Spiridon, Howell, Amy E., Relton, Caroline L., Armstrong, Georgina N., Bondy, Melissa, Zheng, Jie, and Kurian, Kathreena M.
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- 2021
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71. Young adult cancer risk behaviours originate in adolescence: a longitudinal analysis using ALSPAC, a UK birth cohort study
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Wright, Caroline, Heron, Jon, Kipping, Ruth, Hickman, Matthew, Campbell, Rona, and Martin, Richard M.
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- 2021
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72. Electronic Structure: Basic Theory and Practical Methods
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Martin, Richard M.
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- 2020
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73. Factors associated with trial recruitment, preferences, and treatments received were elucidated in a comprehensive cohort study
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Holding, Peter, Mason, Malcolm, Catto, James W.F., Rosario, Derek J., Staffurth, John, Kynaston, Howard, Hughes, Owen, Bollina, Prasad, Doherty, Alan, Gnanapragasam, Vincent, Kockelbergh, Roger, Paul, Alan, Paez, Edgar, Gillatt, David, Rowe, Edward, Oxley, Jon, Donovan, Jenny L., Opmeer, Brent, Young, Grace J., Mills, Nicola, Martin, Richard M., Lane, J. Athene, Metcalfe, Chris, Peters, Tim J., Davis, Michael, Turner, Emma L., Walsh, Eleanor, Neal, David E., and Hamdy, Freddie C.
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- 2019
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74. Energy density in density functional theory: Application to crystalline defects and surfaces
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Yu, Min, Trinkle, Dallas R., and Martin, Richard M.
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Condensed Matter - Materials Science ,Physics - Computational Physics - Abstract
We propose a method to decompose the total energy of a supercell containing defects into contributions of individual atoms, using the energy density formalism within density functional theory. The spatial energy density is unique up to a gauge transformation, and we show that unique atomic energies can be calculated by integrating over Bader and charge-neutral volumes for each atom. Numerically, we implement the energy density method in the framework of the Vienna ab initio simulation package (VASP) for both norm-conserving and ultrasoft pseudopotentials and the projector augmented wave method, and use a weighted integration algorithm to integrate the volumes. The surface energies and point defect energies can be calculated by integrating the energy density over the surface region and the defect region, respectively. We compute energies for several surfaces and defects: the (110) surface energy of GaAs, the mono-vacancy formation energies of Si, the (100) surface energy of Au, and the interstitial formation energy of O in the hexagonal close-packed Ti crystal. The surface and defect energies calculated using our method agree with size-converged calculations of the difference between the total energies of the system with and without the defect. Moreover, the convergence of the defect energies with size can be found from a single calculation., Comment: 25 pages, 6 figures
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- 2010
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75. Electrical conductivity of high-pressure liquid hydrogen by quantum Monte Carlo methods
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Lin, Fei, Morales, Miguel A., Delaney, Kris T., Pierleoni, Carlo, Martin, Richard M., and Ceperley, D. M.
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Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Materials Science - Abstract
We compute the electrical conductivity for liquid hydrogen at high pressure using quantum Monte Carlo. The method uses Coupled Electron-Ion Monte Carlo to generate configurations of liquid hydrogen. For each configuration correlated sampling of electrons is performed in order to calculate a set of lowest many-body eigenstates and current-current correlation functions of the system, which are summed over in the many-body Kubo formula to give AC electrical conductivity directly. The extrapolated DC conductivity at 3000 K for several densities shows a liquid semiconductor to liquid-metal transition at high pressure. Our results are in good agreement with shock-wave data., Comment: 4 pages, 5 figures
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- 2009
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76. Leisure time television watching, computer use and risks of breast, colorectal and prostate cancer: A Mendelian randomisation analysis.
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Papadimitriou, Nikos, Kazmi, Nabila, Dimou, Niki, Tsilidis, Konstantinos K., Martin, Richard M., Lewis, Sarah J., Lynch, Brigid M., Hoffmeister, Michael, Sun-Seog Kweon, Li Li, Milne, Roger L., Sakoda, Lori C., Schoen, Robert E., Phipps, Amanda I., Figueiredo, Jane C., Peters, Ulrike, Dixon-Suen, Suzanne C., Gunter, Marc J., and Murphy, Neil
- Subjects
COLORECTAL cancer ,PROSTATE cancer ,TELEVISION viewing ,LEISURE ,GENOME-wide association studies - Abstract
Background: Sedentary behaviours have been associated with increased risks of some common cancers in epidemiological studies; however, it is unclear if these associations are causal. Methods: We used univariable and multivariable two-sample Mendelian randomisation (MR) to examine potential causal relationships between sedentary behaviours and risks of breast, colorectal and prostate cancer. Genetic variants associated with self-reported leisure television watching and computer use were identified from a recent genome-wide association study (GWAS). Data related to cancer risk were obtained from cancer GWAS consortia. A series of sensitivity analyses were applied to examine the robustness of the results to the presence of confounding. Results: A 1-standard deviation (SD: 1.5h/day) increment in hours of television watching increased risk of breast cancer (OR per 1-SD: 1.15, 95% confidence interval [CI]: 1.05–1.26) and colorectal cancer (OR per 1-SD: 1.32, 95% CI: 1.16– 1.49) while there was little evidence of an association for prostate cancer risk (OR per 1-SD: 0.94, 95% CI: 0.84–1.06). After adjusting for years of education, the effect estimates for television watching were attenuated (breast cancer, OR per 1-SD: 1.08, 95% CI: 0.92–1.27; colorectal cancer, OR per 1-SD: 1.08, 95% CI: 0.90–1.31). Post hoc analyses showed that years of education might have a possible confounding and mediating role in the association between television watching with breast and colorectal cancer. Consistent results were observed for each cancer site according to sex (colorectal cancer), anatomical subsites and cancer subtypes. There was little evidence of associations between genetically predicted computer use and cancer risk. Conclusions: Our univariable analysis identified some positive associations between hours of television watching and risks of breast and colorectal cancer. However, further adjustment for additional lifestyle factors especially years of education attenuated these results. Future studies using objective measures of exposure can provide new insights into the possible role of sedentary behaviour in cancer development. [ABSTRACT FROM AUTHOR]
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- 2024
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77. Kidney Function and Risk of Renal Cell Carcinoma
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Alcala, Karine, primary, Zahed, Hana, additional, Cortez Cardoso Penha, Ricardo, additional, Alcala, Nicolas, additional, Robbins, Hilary A., additional, Smith-Byrne, Karl, additional, Martin, Richard M., additional, Muller, David C., additional, Brennan, Paul, additional, and Johansson, Mattias, additional
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- 2023
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78. Endemic statistical paradoxes in epidemiologic studies distort knowledge on prostate cancer: mitigation and caution of fallacies in prostate cancer causal epidemiological studies
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Cussenot, Olivier, primary, Fromont, Gaelle, additional, Cancel-Tassin, Géraldine, additional, Hamdy, Freddie C., additional, and Martin, Richard M., additional
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- 2023
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79. On the Origin of the 2DEG Carrier Density at the LaAlO$_3$/SrTiO$_3$ Interface
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Popović, Zoran S., Satpathy, Sashi, and Martin, Richard M.
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Condensed Matter - Materials Science - Abstract
Transport measurements of the two-dimensional electron gas (2DEG) at the LaAlO$_3$/SrTiO$_3$ interface have found a density of carriers much lower than expected from the "polar catastrophe" arguments. From a detail density-functional study, we suggest how this discrepancy may be reconciled. We find that electrons occupy multiple subbands at the interface leading to a rich array of transport properties. Some electrons are confined to a single interfacial layer and susceptible to localization, while others with small masses and extended over several layers are expected to contribute to transport., Comment: 4 pages, 7 figures, Accepted in Phys. Rev. Lett
- Published
- 2008
80. Spin resolved energy parametrization of a quasi-one-dimensional electron gas
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Shulenburger, Luke, Casula, Michele, Senatore, Gaetano, and Martin, Richard M.
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Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
By carrying out extensive lattice regularized diffusion Monte Carlo calculations, we study the spin and density dependence of the ground state energy for a quasi-one-dimensional electron gas, with harmonic transverse confinement and long-range $1/r$ interactions. We present a parametrization of the exchange-correlation energy suitable for spin density functional calculations, which fulfills exact low and high density limits., Comment: 9 pages, 3 figures, corrected Eq. 17, added new reference, submitted to J. Phys. A: Math. Theor. as proceedings of the SCCS2008 conference in Camerino, Italy
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- 2008
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81. Renormalization factor and effective mass of the two-dimensional electron gas
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Holzmann, Markus, Bernu, Bernard, Olevano, Valerio, Martin, Richard M., and Ceperley, David M.
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Condensed Matter - Strongly Correlated Electrons - Abstract
We calculate the momentum distribution of the Fermi liquid phase of the homogeneous, two-dimensional electron gas. We show that, close to the Fermi surface, the momentum distribution of a finite system with $N$ electrons approaches its thermodynamic limit slowly, with leading order corrections scaling as $N^{-1/4}$. These corrections dominate the extrapolation of the renormalization factor, $Z$, and the single particle effective mass, $m^*$, to the infinite system size. We show how convergence can be improved analytically. In the range $1 \le r_s \le 10$, we get a lower renormalization factor $Z$ and a higher effective mass, $m^*>m$, compared to the perturbative RPA values., Comment: 4 pages, 3 figures
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- 2008
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82. Molecular hydrogen adsorbed on benzene: insights from a quantum Monte Carlo study
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Beaudet, Todd D., Casula, Michele, Kim, Jeongnim, Sorella, Sandro, and Martin, Richard M.
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Condensed Matter - Materials Science - Abstract
We present a quantum Monte Carlo study of the hydrogen-benzene system where binding is very weak. We demonstrate that the binding is well described at both variational Monte Carlo (VMC) and diffusion Monte Carlo (DMC) levels by a Jastrow correlated single determinant geminal wave function with an optimized compact basis set that includes diffuse orbitals. Agreement between VMC and fixed-node DMC binding energies is found to be within 0.18 mHa, suggesting the calculations are well-converged with respect to the basis. Essentially the same binding is also found in independent DMC calculations using a different trial wave function of a more conventional Slater-Jastrow form, supporting our conclusion that the binding energy is accurate and includes all effects of correlation. We compare with empirical models and previous calculations, and we discuss the physical mechanisms of the interaction, the role of diffuse basis functions, and the charge redistribution in the bond., Comment: 12 pages, 4 figures
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- 2008
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83. Efficient method to calculate total energies of large nanoclusters
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Yu, M., Ramprasad, R., Fernando, G. W., and Martin, Richard M.
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Condensed Matter - Materials Science - Abstract
We present an approach to calculate total energies of nanoclusters based on first principles estimates. For very large clusters the total energy can be separated into surface, edge and corner energies, in addition to bulk contributions. Using this separation and estimating these with direct, first principles calculations, together with the relevant chemical potentials, we have calculated the total energies of Cu and CdSe tetrahedrons containing a large number of atoms. In our work we consider polyhedral clusters so that in addition our work provides direct information on relaxation. For Cu the effects are very small and the clusters vary uniformly from very small to very large sizes. For CdSe there are important variations in surface and edge structures for specific sizes; nevertheless, the approach can be used to extrapolate to large non-stoichiometric clusters with polar surfaces., Comment: 5 pages, 3 figures and 2 tables
- Published
- 2008
84. Developing new age-specific prostate-specific antigen thresholds for testing for prostate cancer
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Gilbert, Rebecca, Tilling, Kate, Martin, Richard M., Lane, J. Athene, Davis, Michael, Hamdy, Freddie C., Neal, David E., Donovan, Jenny L., and Metcalfe, Chris
- Published
- 2018
85. Disorder Enhanced Spin Polarization in Diluted Magnetic Semiconductors
- Author
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Lee, Byounghak, Cartoixa, Xavier, Trivedi, Nandini, and Martin, Richard M.
- Subjects
Condensed Matter - Disordered Systems and Neural Networks ,Condensed Matter - Materials Science - Abstract
We present a theoretical study of diluted magnetic semiconductors that includes spin-orbit coupling within a realistic host band structure and treats explicitly the effects of disorder due to randomly substituted Mn ions. While spin-orbit coupling reduces the spin polarization by mixing different spin states in the valence bands, we find that disorder from Mn ions enhances the spin polarization due to formation of ferromagnetic impurity clusters and impurity bound states. The disorder leads to large effects on the hole carriers which form impurity bands as well as hybridizing with the valence band. For Mn doping 0.01 < x < 0.04, the system is metallic with a large effective mass and low mobility.
- Published
- 2007
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86. The Finite Size Error in Many-body Simulations with long-Ranged Interactions
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Chiesa, Simone, Ceperley, David M., Martin, Richard M., and Holzmann, Markus
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Condensed Matter - Other Condensed Matter ,Condensed Matter - Materials Science - Abstract
We discuss the origin of the finite size error of the energy in many-body simulation of systems of charged particles and we propose a correction based on the random phase approximation at long wave lengths. The correction comes from contributions mainly determined by the organized collective oscillations of the interacting system. Finite size corrections, both on kinetic and potential energy, can be calculated within a single simulation. Results are presented for the electron gas and silicon., Comment: 4 pages, 4 figures, submitted to PRL; corrected typos
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- 2006
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87. Genetically proxied therapeutic inhibition of antihypertensive drug targets and risk of common cancers: A mendelian randomization analysis
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Yarmolinsky, James, Díez-Obrero, Virginia, Richardson, Tom G., Pigeyre, Marie, Sjaarda, Jennifer, Paré, Guillaume, Walker, Venexia M., Vincent, Emma E., Tan, Vanessa Y., Obón-Santacana, Mireia, Albanes, Demetrius, Hampe, Jochen, Gsur, Andrea, Hampel, Heather, Pai, Rish K., Jenkins, Mark, Gallinger, Steven, Casey, Graham, Zheng, Wei, Amos, Christopher I., Smith, George Davey, Martin, Richard M., and Moreno, Victor
- Subjects
Colorectal cancer -- Risk factors ,ACE inhibitors -- Complications and side effects ,Drug targeting -- Models -- Genetic aspects ,Hypertension -- Drug therapy -- Models ,Biological sciences - Abstract
Background Epidemiological studies have reported conflicting findings on the potential adverse effects of long-term antihypertensive medication use on cancer risk. Naturally occurring variation in genes encoding antihypertensive drug targets can be used as proxies for these targets to examine the effect of their long-term therapeutic inhibition on disease outcomes. Methods and findings We performed a mendelian randomization analysis to examine the association between genetically proxied inhibition of 3 antihypertensive drug targets and risk of 4 common cancers (breast, colorectal, lung, and prostate). Single-nucleotide polymorphisms (SNPs) in ACE, ADRB1, and SLC12A3 associated (P < 5.0 x 10.sup.-8) with systolic blood pressure (SBP) in genome-wide association studies (GWAS) were used to proxy inhibition of angiotensin-converting enzyme (ACE), [beta]-1 adrenergic receptor (ADRB1), and sodium-chloride symporter (NCC), respectively. Summary genetic association estimates for these SNPs were obtained from GWAS consortia for the following cancers: breast (122,977 cases, 105,974 controls), colorectal (58,221 cases, 67,694 controls), lung (29,266 cases, 56,450 controls), and prostate (79,148 cases, 61,106 controls). Replication analyses were performed in the FinnGen consortium (1,573 colorectal cancer cases, 120,006 controls). Cancer GWAS and FinnGen consortia data were restricted to individuals of European ancestry. Inverse-variance weighted random-effects models were used to examine associations between genetically proxied inhibition of these drug targets and risk of cancer. Multivariable mendelian randomization and colocalization analyses were employed to examine robustness of findings to violations of mendelian randomization assumptions. Genetically proxied ACE inhibition equivalent to a 1-mm Hg reduction in SBP was associated with increased odds of colorectal cancer (odds ratio (OR) 1.13, 95% CI 1.06 to 1.22; P = 3.6 x 10.sup.-4). This finding was replicated in the FinnGen consortium (OR 1.40, 95% CI 1.02 to 1.92; P = 0.035). There was little evidence of association of genetically proxied ACE inhibition with risk of breast cancer (OR 0.98, 95% CI 0.94 to 1.02, P = 0.35), lung cancer (OR 1.01, 95% CI 0.92 to 1.10; P = 0.93), or prostate cancer (OR 1.06, 95% CI 0.99 to 1.13; P = 0.08). Genetically proxied inhibition of ADRB1 and NCC were not associated with risk of these cancers. The primary limitations of this analysis include the modest statistical power for analyses of drug targets in relation to some less common histological subtypes of cancers examined and the restriction of the majority of analyses to participants of European ancestry. Conclusions In this study, we observed that genetically proxied long-term ACE inhibition was associated with an increased risk of colorectal cancer, warranting comprehensive evaluation of the safety profiles of ACE inhibitors in clinical trials with adequate follow-up. There was little evidence to support associations across other drug target-cancer risk analyses, consistent with findings from short-term randomized controlled trials for these medications., Author(s): James Yarmolinsky 1,2,*, Virginia Díez-Obrero 3,4,5, Tom G. Richardson 1,2, Marie Pigeyre 6,7,8, Jennifer Sjaarda 6,7,9, Guillaume Paré 6,7,9,10, Venexia M. Walker 1,2,11, Emma E. Vincent 1,2,12, Vanessa Y. [...]
- Published
- 2022
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88. Role of the spin-orbit splitting and the dynamical fluctuations in the Si(557)-Au surface
- Author
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Sanchez-Portal, Daniel, Riikonen, Sampsa, and MArtin, Richard M.
- Subjects
Condensed Matter - Materials Science - Abstract
Our it ab initio calculations show that spin-orbit coupling is crucial to understand the electronic structure of the Si(557)-Au surface. The spin-orbit splitting produces the two one-dimensional bands observed in photoemission, which were previously attributed to spin-charge separation in a Luttinger liquid. This spin splitting might have relevance for future device applications. We also show that the apparent Peierls-like transition observed in this surface by scanning tunneling microscopy is a result of the dynamical fluctuations of the step-edge structure, which are quenched as the temperature is decreased.
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- 2005
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89. Statins as Potential Chemoprevention or Therapeutic Agents in Cancer: a Model for Evaluating Repurposed Drugs
- Author
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Joharatnam-Hogan, Nalinie, Alexandre, Leo, Yarmolinsky, James, Lake, Blossom, Capps, Nigel, Martin, Richard M, Ring, Alistair, Cafferty, Fay, and Langley, Ruth E
- Published
- 2021
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90. A prospective cohort and extended comprehensive-cohort design provided insights about the generalizability of a pragmatic trial: the ProtecT prostate cancer trial
- Author
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Bollina, Prasad, Catto, James, Doble, Andrew, Doherty, Alan, Gillatt, David, Gnanapragasam, Vincent, Holding, Peter, Hughes, Owen, Kockelbergh, Roger, Kynaston, Howard, Mason, Malcolm, Oxley, Jon, Paul, Alan, Paez, Edgar, Rosario, Derek J., Rowe, Edward, Staffurth, John, Donovan, Jenny L., Young, Grace J., Walsh, Eleanor I., Metcalfe, Chris, Lane, J. Athene, Martin, Richard M., Tazewell, Marta K., Davis, Michael, Peters, Tim J., Turner, Emma L., Mills, Nicola, Khazragui, Hanan, Khera, Tarnjit K., Neal, David E., and Hamdy, Freddie C.
- Published
- 2018
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91. Estimating the sensitivity of a prostate cancer screening programme for different PSA cut-off levels: A UK case study
- Author
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Leal, Jose, Welton, Nicky J., Martin, Richard M., Donovan, Jenny, Hamdy, Freddie, Neal, David, Noble, Sian, Lane, Athene, and Wolstenholme, Jane
- Published
- 2018
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92. Jahn-Teller Distortion and Ferromagnetism in the Dilute Magnetic Semiconductors GaN:Mn
- Author
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Luo, Xuan and Martin, Richard M.
- Subjects
Condensed Matter - Materials Science - Abstract
Using first-principles total-energy methods, we investigate Jahn-Teller distortions in III-V dilute magnetic semiconductors, GaAs:Mn and GaN:Mn in the cubic zinc blende structure. The results for an isolated Mn impurity on a Ga site show that there is no appreciable effect in GaAs, whereas, in GaN there is a Jahn-Teller effect in which the symmetry around the impurity changes from T$_{d}$ to D$_{2d}$ or to C$_{2v}$. The large effect in GaN occurs because of the localized d$^4$ character, which is further enhanced by the distortion. The lower symmetry should be detectable experimentally in cubic GaN with low Mn concentration, and should be affected by charge compensation (reductions of holes and conversion of Mn ions to d$^5$ with no Jahn-Teller effect). Jahn-Teller effect is greatly reduced because the symmetry at each Mn site is lowered due to the Mn-Mn interaction. The tendency toward ferromagnetism is found to be stronger in GaN:Mn than in GaAs:Mn and to be only slightly reduced by charge compensation., Comment: 6 pages, 3 figures
- Published
- 2004
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93. Spin-Orbit Effects in Diluted Magnetic Semiconductors
- Author
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Lee, Byounghak, Cartoixa, Xavier, Trivedi, Nandini, and Martin, Richard M.
- Subjects
Condensed Matter - Materials Science - Abstract
We present a theoretical study of diluted magnetic semiconductors that treats the local sp-d exchange interaction J between the itinerant carriers and the Mn d electrons within a realistic band structure and goes beyond previous mean-field approaches. In case of (Ga,Mn)As, we find that strong exchange potentials tightly bind carriers near impurity sites. Spin-orbit coupling is found to have a more pronounced effect on spin polarization at weak coupling and this feature can be exploited for magnetotransport. For low doping regime, we predict that spin-orbit coupling splits impurity bands and can induce a novel insulating phase., Comment: 4 pages, 5 figures
- Published
- 2004
94. Electron-Phonon Interactions in C$_{28}$-derived Molecular Solids
- Author
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Romero, Nichols A., Kim, Jeongnim, and Martin, Richard M.
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Materials Science - Abstract
We present {\it ab initio} density-functional calculations of molecular solids formed from C$_{28}$-derived closed-shell fullerenes. Solid C$_{28}$H$_4$ is found to bind weakly and exhibits many of the electronic structure features of solid C$_{60}$ with an enhanced electron-phonon interaction potential. We show that chemical doping of this structure is feasible, albeit more restrictive than its C$_{60}$ counterpart, with an estimated superconducting transition temperature exceeding those of the alkali-doped C$_{60}$ solids., Comment: Lower quality postscript file for Figure 1 is used in the manuscript in order to meet submission quota for pre-print server. Higher quality postscript file available from author: naromero@alum.mit.edu This article has been updated to reflect changes incorporated during the peer review process. It is published in PRB 70, 140504(R) 2004
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- 2004
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95. The Albatross Plot: A Novel Graphical Tool for Presenting Results of Diversely Reported Studies in a Systematic Review
- Author
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Harrison, Sean, Jones, Hayley E., Martin, Richard M., Lewis, Sarah J., and Higgins, Julian P. T.
- Abstract
Meta-analyses combine the results of multiple studies of a common question. Approaches based on effect size estimates from each study are generally regarded as the most informative. However, these methods can only be used if comparable effect sizes can be computed from each study, and this may not be the case due to variation in how the studies were done or limitations in how their results were reported. Other methods, such as vote counting, are then used to summarize the results of these studies, but most of these methods are limited in that they do not provide any indication of the magnitude of effect. We propose a novel plot, the albatross plot, which requires only a 1-sided P value and a total sample size from each study (or equivalently a 2-sided P value, direction of effect and total sample size). The plot allows an approximate examination of underlying effect sizes and the potential to identify sources of heterogeneity across studies. This is achieved by drawing contours showing the range of effect sizes that might lead to each P value for given sample sizes, under simple study designs. We provide examples of albatross plots using data from previous meta-analyses, allowing for comparison of results, and an example from when a meta-analysis was not possible.
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- 2017
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96. Response to Comment on Delphi Analysis of Relevant Comparators in a Cost-Effectiveness Model of Prostate Cancer Screening
- Author
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Keeney, Edna, Thom, Howard, Turner, Emma, Martin, Richard M., and Sanghera, Sabina
- Published
- 2021
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97. First principles study of the Si(557)-Au surface
- Author
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Sanchez-Portal, Daniel and Martin, Richard M.
- Subjects
Condensed Matter - Materials Science - Abstract
We have performed a density functional study of fifteen different structural models of the Si(557)-Au surface reconstruction. Here we present a brief summary of the main structural trends obtained for the more favourable models, focusing afterwards in a detailed description of the atomic structure, electronic properties and, simulated STM images of the most stable model predicted by our calculations. This structure is in very good agreement with that recently proposed from X-ray diffraction measurements by Robinson et al. [Phys. Rev. Lett. 88, (2002) 096194]., Comment: 12 pages, including two figures, in preprint format. Submitted to Surface Science on July 2002 (Proceedings of the ECOSS-21 conference)
- Published
- 2002
98. Calculation of the optical response of C60 and Na8 using time-dependent density functional theory and local orbitals
- Author
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Tsolakidis, Argyrios, Sanchez-Portal, Daniel, and Martin, Richard M.
- Subjects
Condensed Matter - Materials Science ,Condensed Matter - Strongly Correlated Electrons - Abstract
We report on a general method for the calculation of the frequency-dependent optical response of clusters based upon time-dependent density functional theory (TDDFT). The implementation is done using explicit propagation in the time domain and a self-consistent program that uses a linear combination of atomic orbitals (LCAO). Our actual calculations employ the SIESTA program, which is designed to be fast and accurate for large clusters. We use the adiabatic local density approximation to account for exchange and correlation effects. Results are presented for the imaginary part of the linear polarizability, Im [\alpha(w)], and the dipole strength function, S(w), of C60 and Na8, compared to previous calculations and to experiment. We also show how to calculate the integrated frequency-dependent second order non-linear polarizability for the case of a step function electric field, \gamma_{step}(w), and present results for C60., Comment: 11 pages with 6 postscript figures. Submitted for publication
- Published
- 2001
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99. Bonding, Moment Formation, and Magnetic Interactions in Ca14MnBi11 and Ba14MnBi11
- Author
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Sanchez-Portal, D., Martin, Richard M., Kauzlarich, S. M., and Pickett, W. E.
- Subjects
Condensed Matter - Materials Science - Abstract
The ``14-1-11'' phase compounds based on magnetic Mn ions and typified by Ca14MnBi11 and Ba14MnBi11 show unusual magnetic behavior, but the large number (104) of atoms in the primitive cell has precluded any previous full electronic structure study. Using an efficient, local orbital based method within the local spin density approximation to study the electronic structure, we find a gap between a bonding valence band complex and an antibonding conduction band continuum. The bonding bands lack one electron per formula unit of being filled, making them low carrier density p-type metals. The hole resides in the MnBi4 tetrahedral unit and partially compensates the high spin d^5 Mn moment, leaving a net spin near 4 \mu_B that is consistent with experiment. These manganites are composed of two disjoint but interpenetrating `jungle gym' networks of spin 4/2 MnBi4^{9-} units with ferromagnetic interactions within the same network, and weaker couplings between the networks whose sign and magnitude is sensitive to materials parameters. Ca14MnBi11 is calculated to be ferromagnetic as observed, while for Ba14MnBi11 (which is antiferromagnetic) the ferro- and antiferromagnetic states are calculated to be essentially degenerate. The band structure of the ferromagnetic states is very close to half metallic., Comment: 17 pages, containing 10 postscript figures and 5 tables. Two additional figures (Fig.8 and 11 of the paper) are provided in JPG format in separate files. Submitted to Phys. Rev. B on September 20th 2001
- Published
- 2001
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100. Two distinct metallic bands associated with monatomic Au wires on the Si(557)-Au surface
- Author
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Sanchez-Portal, Daniel, Gale, Julian D., Garcia, Alberto, and Martin, Richard M.
- Subjects
Condensed Matter - Materials Science ,Condensed Matter - Strongly Correlated Electrons - Abstract
The Si(557)-Au surface, containing monatomic Au wires parallel to the steps, has been proposed as an experimental realization of an ideal one-dimensional metal. In fact, recent photoemission experiments on this system (Nature 402, 504 (1999)) found two peaks that were interpreted in terms of the spin-charge separation in a Luttinger liquid. Our first-principles density functional calculations reveal two metallic bands associated with Au-Si bonds, instead of the single band expected from the Au 6s states, providing an alternative explanation for the experimental observations., Comment: 5 pages with 3 postscript figures. Submitted to PRL on May 10th 2001
- Published
- 2001
- Full Text
- View/download PDF
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