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Themstrup L, Pellacani G, Welzel J, Holmes J, Jemec G, Ulrich M. In vivomicrovascular imaging of cutaneous actinic keratosis, Bowen's disease and squamous cell carcinoma using dynamic optical coherence tomography. J Eur Acad Dermatol Venereol 2017; 31:1655-1662. [DOI: 10.1111/jdv.14335] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 04/12/2017] [Indexed: 11/29/2022]
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Haux R, Geissbuhler A, Holmes J, Jaulent MC, Koch S, Kulikowski CA, Lehmann CU, McCray AT, Séroussi B, Soualmia LF, van Bemmel JH. On Contributing to the Progress of Medical Informatics as Publisher. Yearb Med Inform 2017; 26:9-15. [PMID: 28480470 DOI: 10.15265/iy-2017-003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
May 1st, 2017, will mark Dieter Bergemann's 80th birthday. As Chief Executive Officer and Owner of Schattauer Publishers from 1983 to 2016, the biomedical and health informatics community owes him a great debt of gratitude. The past and present editors of Methods of Information in Medicine, the IMIA Yearbook of Medical Informatics, and Applied Clinical Informatics want to honour and thank Dieter Bergemann by providing a brief biography that emphasizes his contributions, by reviewing his critical role as an exceptionally supportive publisher for Schattauer's three biomedical and health informatics periodicals, and by sharing some personal anecdotes. Over the past 40 years, Dieter Bergemann has been an influential, if behind-the-scenes, driving force in biomedical and health informatics publications, helping to ensure success in the dissemination of our field's research and practice.
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Herrmann D, Sinnett P, Holmes J, Khan S, Koller C, Vassar M. Statistical controversies in clinical research: publication bias evaluations are not routinely conducted in clinical oncology systematic reviews. Ann Oncol 2017; 28:931-937. [DOI: 10.1093/annonc/mdw691] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Thompson R, Lu Y, Potvin M, Holmes J, Di Prospero L, Keller B, Szumacher E, Liszewski B, Catton P, Giuliani M, Pitcher B, Pintilie M, Bissonnette JP. Hazards and incidents: Detection and learning in radiation medicine, a comparison of 2 educational interventions. Pract Radiat Oncol 2017; 7:e431-e438. [PMID: 28377137 DOI: 10.1016/j.prro.2017.02.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 02/16/2017] [Accepted: 02/19/2017] [Indexed: 11/18/2022]
Abstract
PURPOSE Interprofessional, educational live simulations were compared with group discussion-based exercises in terms of their ability to improve radiation medicine trainees' ability to detect hazards and incidents and understand behaviors that may prevent them. METHODS AND MATERIALS Trainees and recent graduates of radiation therapy, medical physics, and radiation oncology programs were recruited and randomized to either a simulation-based or group discussion-based training intervention. Participants engaged in hazard and incident detection, analysis, and a discussion of potential preventive measures and the concept of the "highly reliable team." A video examination tool modeled on actual incidents, using 5-minute videos created by faculty, students, and volunteers, was created to test hazard and incident recognition ability before and after training. Hazard and incident detection sensitivity and specificity analyses were conducted, and a survey of the participants' and facilitators' perceptions was conducted. RESULTS Twenty-seven participants were assigned to the simulation (n = 15) or discussion group (n = 12). Hazard and incident-detection sensitivity ranged from 0.04 to 0.56 before and 0.04 to 0.35 after training for the discussion and simulation groups, respectively. The pre- and posttraining difference in sensitivity between groups was 0.03 (P = .75) for the minimum and 0.33 (P = .034) for the maximum reaction time. Participant perceptions of the training's educational value in a variety of domains ranged from a mean score of 6.58 to 8.17 and 7 to 8.07 for the discussion and simulation groups, respectively. Differences were not statistically significant. Twenty-six of the 27 participants indicated that they would recommend this event to a colleague. CONCLUSIONS Participants' ability to detect hazards and incidents as portrayed in 5-minute videos in this study was low both before and after training, and simulation-based training was not superior to discussion-based training. However, levels of satisfaction and perceptions of the training's educational value were high, especially with simulation-based training.
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Murphy J, Holmes J, Brooks C. Measurements of Daily Energy Intake and Total Energy Expenditure in People with Dementia in Care Homes: The Use of Wearable Technology. J Nutr Health Aging 2017; 21:927-932. [PMID: 28972246 PMCID: PMC5602067 DOI: 10.1007/s12603-017-0870-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 06/21/2016] [Indexed: 11/23/2022]
Abstract
OBJECTIVE To estimate daily total energy expenditure (TEE) using a physical activity monitor, combined with dietary assessment of energy intake to assess the relationship between daily energy expenditure and patterns of activity with energy intake in people with dementia living in care homes. DESIGN AND SETTING A cross-sectional study in care homes in the UK. PARTICIPANTS Twenty residents with confirmed dementia diagnosis were recruited from two care homes that specialised in dementia care. MEASUREMENTS A physical activity monitor (SensewearTM Armband, Body Media, Pittsburgh, PA) was employed to objectively determine total energy expenditure, sleep duration and physical activity. The armband was placed around the left upper triceps for up to 7 days. Energy intake was determined by weighing all food and drink items over 4 days (3 weekdays and 1 weekend day) including measurements of food wastage. RESULTS The mean age was 78.7 (SD ± 11.8) years, Body Mass Index (BMI) 23.0 (SD ± 4.2) kg/m2; 50% were women. Energy intake (mean 7.4; SD ± 2.6) MJ/d) was correlated with TEE (mean 7.6; SD ± 1.8 MJ/d; r=0.49, p<0.05). Duration of sleeping ranged from 0.4-12.5 (mean 6.1) hrs/d and time spent lying down was 1.3-16.0 (8.3) hrs/d. On average residents spent 17.9 (6.3-23.4) hrs/d undertaking sedentary activity. TEE was correlated with BMI (r=0.52, p<0.05) and body weight (r=0.81, p<0.001) but inversely related to sleep duration (r=-0.59, p<0.01) and time lying down (r=-0.62, p<0.01). Multiple linear regression analysis revealed that after taking BMI, sleep duration and time spent lying down into account, TEE was no longer correlated with energy intake. CONCLUSIONS The results show the extent to which body mass, variable activity and sleep patterns may be contributing to TEE and together with reduced energy intake, energy requirements were not satisfied. Thus wearable technology has the potential to offer real-time monitoring to provide appropriate nutrition management that is more person-centred to prevent weight loss in dementia.
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Tunik MG, Powell EC, Mahajan P, Schunk JE, Jacobs E, Miskin M, Zuspan SJ, Wootton-Gorges S, Atabaki SM, Hoyle JD, Holmes JF, Dayan PS, Kuppermann N, Gerardi M, Tunik M, Tsung J, Melville K, Lee L, Mahajan P, Dayan P, Nadel F, Powell E, Atabaki S, Brown K, Glass T, Hoyle J, Cooper A, Jacobs E, Monroe D, Borgialli D, Gorelick M, Bandyopadhyay S, Bachman M, Schamban N, Callahan J, Kuppermann N, Holmes J, Lichenstein R, Stanley R, Badawy M, Babcock-Cimpello L, Schunk J, Quayle K, Jaffe D, Lillis K, Kuppermann N, Alpern E, Chamberlain J, Dean J, Gerardi M, Goepp J, Gorelick M, Hoyle J, Jaffe D, Johns C, Levick N, Mahajan P, Maio R, Melville K, Miller S, Monroe D, Ruddy R, Stanley R, Treloar D, Tunik M, Walker A, Kavanaugh D, Park H, Dean M, Holubkov R, Knight S, Donaldson A, Chamberlain J, Brown M, Corneli H, Goepp J, Holubkov R, Mahajan P, Melville K, Stremski E, Tunik M, Gorelick M, Alpern E, Dean J, Foltin G, Joseph J, Miller S, Moler F, Stanley R, Teach S, Jaffe D, Brown K, Cooper A, Dean J, Johns C, Maio R, Mann N, Monroe D, Shaw K, Teitelbaum D, Treloar D, Stanley R, Alexander D, Brown J, Gerardi M, Gregor M, Holubkov R, Lillis K, Nordberg B, Ruddy R, Shults M, Walker A, Levick N, Brennan J, Brown J, Dean J, Hoyle J, Maio R, Ruddy R, Schalick W, Singh T, Wright J. Clinical Presentations and Outcomes of Children With Basilar Skull Fractures After Blunt Head Trauma. Ann Emerg Med 2016; 68:431-440.e1. [DOI: 10.1016/j.annemergmed.2016.04.058] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 04/18/2016] [Accepted: 04/27/2016] [Indexed: 12/17/2022]
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Themstrup L, Welzel J, Ciardo S, Kaestle R, Ulrich M, Holmes J, Whitehead R, Sattler E, Kindermann N, Pellacani G, Jemec G. Validation of Dynamic optical coherence tomography for non-invasive, in vivo microcirculation imaging of the skin. Microvasc Res 2016; 107:97-105. [DOI: 10.1016/j.mvr.2016.05.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 05/13/2016] [Accepted: 05/23/2016] [Indexed: 11/15/2022]
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Matrosic C, McMillan A, Holmes J, Bednarz B, Culberson W. SU-F-T-477: Investigation of DEFGEL Dosimetry Using MRI. Med Phys 2016. [DOI: 10.1118/1.4956662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Cheshire K, Morgan R, Holmes J. The potential for geochemical discrimination of single- and mixed-source soil samples from close proximity urban parkland locations. AUST J FORENSIC SCI 2016. [DOI: 10.1080/00450618.2016.1144789] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Holmes J, Pask CM, Willans CE. Chelating N-heterocyclic carbene–carboranes offer flexible ligand coordination to IrIII, RhIII and RuII: effect of ligand cyclometallation in catalytic transfer hydrogenation. Dalton Trans 2016; 45:15818-15827. [DOI: 10.1039/c6dt02079h] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
NHC–carborane ligands, with flexible coordination through either the carbon or the boron atom of the carborane, provide effective transfer hydrogenation catalysts.
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Holmes J, Pask CM, Fox MA, Willans CE. Tethered N-heterocyclic carbene–carboranes: unique ligands that exhibit unprecedented and versatile coordination modes at rhodium. Chem Commun (Camb) 2016; 52:6443-6. [DOI: 10.1039/c6cc01650b] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hybrid ligands combining an N-heterocyclic carbene tethered with carboranes covalently coordinate to RhI through both NHC and carborane moieties.
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MacDonald IR, Garcia-Pineda O, Beet A, Daneshgar Asl S, Feng L, Graettinger G, French-McCay D, Holmes J, Hu C, Huffer F, Leifer I, Muller-Karger F, Solow A, Silva M, Swayze G. Natural and unnatural oil slicks in the Gulf of Mexico. JOURNAL OF GEOPHYSICAL RESEARCH. OCEANS 2015; 120:8364-8380. [PMID: 27774370 PMCID: PMC5064732 DOI: 10.1002/2015jc011062] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Accepted: 11/25/2015] [Indexed: 05/05/2023]
Abstract
When wind speeds are 2-10 m s-1, reflective contrasts in the ocean surface make oil slicks visible to synthetic aperture radar (SAR) under all sky conditions. Neural network analysis of satellite SAR images quantified the magnitude and distribution of surface oil in the Gulf of Mexico from persistent, natural seeps and from the Deepwater Horizon (DWH) discharge. This analysis identified 914 natural oil seep zones across the entire Gulf of Mexico in pre-2010 data. Their ∼0.1 µm slicks covered an aggregated average of 775 km2. Assuming an average volume of 77.5 m3 over an 8-24 h lifespan per oil slick, the floating oil indicates a surface flux of 2.5-9.4 × 104 m3 yr-1. Oil from natural slicks was regionally concentrated: 68%, 25%, 7%, and <1% of the total was observed in the NW, SW, NE, and SE Gulf, respectively. This reflects differences in basin history and hydrocarbon generation. SAR images from 2010 showed that the 87 day DWH discharge produced a surface-oil footprint fundamentally different from background seepage, with an average ocean area of 11,200 km2 (SD 5028) and a volume of 22,600 m3 (SD 5411). Peak magnitudes of oil were detected during equivalent, ∼14 day intervals around 23 May and 18 June, when wind speeds remained <5 m s-1. Over this interval, aggregated volume of floating oil decreased by 21%; area covered increased by 49% (p < 0.1), potentially altering its ecological impact. The most likely causes were increased applications of dispersant and surface burning operations.
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De Carvalho N, Ciardo S, Cesinaro AM, Jemec GBE, Ulrich M, Welzel J, Holmes J, Pellacani G. In vivo
micro-angiography by means of speckle-variance optical coherence tomography (SV-OCT) is able to detect microscopic vascular changes in naevus to melanoma transition. J Eur Acad Dermatol Venereol 2015; 30:e67-e68. [DOI: 10.1111/jdv.13311] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Kumaravel A, Stevens T, Papachristou GI, Muddana V, Bhatt A, Lee PJ, Holmes J, Lopez R, Whitcomb DC, Parsi MA. A Model to Predict the Severity of Acute Pancreatitis Based on Serum Level of Amylase and Body Mass Index. Clin Gastroenterol Hepatol 2015; 13:1496-501. [PMID: 25818080 DOI: 10.1016/j.cgh.2015.03.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 03/11/2015] [Accepted: 03/13/2015] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS Most patients with acute pancreatitis (AP) develop mild disease, but up to 20% develop severe disease. Many clinicians monitor serum levels of amylase and lipase in an attempt to predict the disease course, but this strategy has not been recommended by practice guidelines. We performed a retrospective analysis to determine whether the percentage changes in amylase and lipase were associated with the severity of disease that developed in patients with AP. METHODS We analyzed data collected from 182 consecutive patients with AP (21 with severe AP) admitted to the Cleveland Clinic from January 2008 through May 2010 (discover cohort). The association between 11 different factors and the severity of AP were assessed by univariable analysis; multivariable models were explored through stepwise selection regression. The percentage change in the serum level of amylase was calculated as follows: ([amylase day 1 - amylase day 2]/amylase day 1) × 100. The percentage change in amylase and body mass index (BMI) were combined to generate a z-score (z = -5.9 + [0.14 × BMI] + [0.01 × percentage change in amylase]), which was converted into a probability distribution called the change in amylase and BMI (CAB) score. The CAB score was validated using the AP database at the University of Pittsburgh Medical Center (140 patients, 35 with severe AP); we calculated p-scores for each patient and estimated the area under the receiver operating characteristics curve values. RESULTS Univariable analysis identified the percentage change in the serum level of amylase and other factors to be associated significantly with the severity of AP (P = .017). The CAB score was best at identifying patients who developed severe AP, with an area under the receiver operating characteristics curve value of 0.79 in the discovery cohort (95% confidence interval, 0.71-0.87) and 0.731 in the validation cohort (95% confidence interval, 0.61-0.84). CONCLUSIONS We developed a model to identify patients most likely to develop severe AP based on the percentage changes in serum level of amylase during the first 2 days after admission to the hospital and BMI.
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Jones D, Hicks P, Currey J, Holmes J, Fennessy GJ, Hillman K, Psirides A, Rai S, Singh MY, Pilcher DV, Bhonagiri D, Hart GK, Fugaccia E. Findings of the first ANZICS conference on the role of intensive care in Rapid Response Teams. Anaesth Intensive Care 2015; 43:369-79. [PMID: 25943612 DOI: 10.1177/0310057x1504300314] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Rapid Response Teams (RRTs) are specialised teams introduced into hospitals to improve the outcomes of deteriorating ward patients. Although Rapid Response Systems (RRSs) were developed by the intensive care unit (ICU) community, there is variability in their delivery, and consultant involvement, supervision and leadership appears to be relatively infrequent. In July 2014, the Australian and New Zealand Intensive Care Society (ANZICS) convened the first conference on the role of intensive care medicine in RRTs in Australia and New Zealand. The conference explored RRSs in the broader role of patient safety, resourcing and staffing of RRTs, effect on ICU workload, different RRT models, the outcomes of RRT patients and original research projects in the area of RRSs. Issues around education and training of both ICU registrars and nurses were examined, and the role of team training explored. Measures to assess the effectiveness of the RRS and RRT at the level of health system and hospital, team performance and team effectiveness were discussed, and the need to develop a bi-national ANZICS RRT patient database was presented. Strategies to prevent patient deterioration in the 'pre-RRT' period were discussed, including education of ward nurses and doctors, as well as an overarching governance structure. The role of the ICU in deteriorating ward patients was debated and an integrated model of acute care presented. This article summarises the findings of the conference and presents recommendations on the role of intensive care medicine in RRTs in Australia and New Zealand.
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Borer JS, Wallis J, Hochreiter C, Holmes J, Moses JW. Prognostic value of left ventricular dysfunction at rest and during exercise in patients with coronary artery disease. Adv Cardiol 2015; 34:179-85. [PMID: 3538801 DOI: 10.1159/000413050] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Zem G, Cooperman B, Bahri F, Mahjoubi A, Warner N, Malekian L, Mirebrahimian R, Pistalu M, Khrayan L, Patel M, Pastrano K, Choi E, Baronian T, Gilani O, Cardenas A, Hambarsoomian A, Gomez D, Gallgos F, Holmes J, Vahdati V, Jorshari L, Grigorian P, Ohanessian K, Baum E, Majarian G, Aldzhyan K, Manasyan H, Allatabakhsh N, Oppenheimer S. Reliability of Yeast Unclumping Assay, a Model for Testing Potentially Clinically Useful Reagents. FASEB J 2015. [DOI: 10.1096/fasebj.29.1_supplement.925.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Lewis A, Blackney M, Torvinen S, Holmes J, Osborne M, Dale J, Chandler S, Plich A. The Budget Impact of Duoresp® Spiromax® (Budesonide + Formoterol Fumarate Dihydrate) Compared With Symbicort® Turbohaler® for the Management of Asthma and Chronic Obstructive Pulmonary Disease in the United Kingdom: Impact on Health Care Costs and Inhalation Technique. VALUE IN HEALTH : THE JOURNAL OF THE INTERNATIONAL SOCIETY FOR PHARMACOECONOMICS AND OUTCOMES RESEARCH 2014; 17:A591. [PMID: 27202019 DOI: 10.1016/j.jval.2014.08.2027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
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Cherryman F, Cunningham V, Aubin M, Holmes J, Serrick C, Tsirigotis D. SIMULATED TEAM-BASED CPB EMERGENCY PREPAREDNESS TRAINING. Can J Cardiol 2014. [DOI: 10.1016/j.cjca.2014.07.402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Hughes R, Lucas J, Divers J, Holmes J, Krane S, Hemal A, Frizzell B. Predictors of Locoregional and Intravesical Recurrence Among Patients Treated With Nephroureterectomy for Urothelial Tract Carcinoma. Int J Radiat Oncol Biol Phys 2014. [DOI: 10.1016/j.ijrobp.2014.05.1453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Holmes J, Mirams M, Mackie E, Whitton C. Subchondral Bone Remodelling Is More Active in Resting Than Training Thoroughbred Racehorses. Equine Vet J 2014. [DOI: 10.1111/evj.12267_83] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Hartley LC, Igbinedion E, Holmes J, Thorogood M, Clarke A, Stranges S, Hooper L, Rees K. OP75 Increased Consumption of Fruit and Vegetables for the Primary Prevention of Cardiovascular Diseases – A Cochrane Systematic Review. Br J Soc Med 2013. [DOI: 10.1136/jech-2013-203126.75] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Kapdi AR, Whitwood AC, Williamson DC, Lynam JM, Burns MJ, Williams TJ, Reay AJ, Holmes J, Fairlamb IJS. The elusive structure of Pd2(dba)3. Examination by isotopic labeling, NMR spectroscopy, and X-ray diffraction analysis: synthesis and characterization of Pd2(dba-Z)3 complexes. J Am Chem Soc 2013; 135:8388-99. [PMID: 23701049 DOI: 10.1021/ja403259c] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Pd(0)2(dba)3 (dba = E,E-dibenzylidene acetone) is the most widely used Pd(0) source in Pd-mediated transformations. Pd(0)2(dba-Z)3 (Z = dba aryl substituents) complexes exhibit remarkable and differential catalytic performance in an eclectic array of cross-coupling reactions. The precise structure of these types of complexes has been confounding, since early studies in 1970s to the present day. In this study the solution and solid-state structures of Pd(0)2(dba)3 and Pd(0)2(dba-Z)3 have been determined. Isotopic labeling ((2)H and (13)C) has allowed the solution structures of the freely exchanging major and minor isomers of Pd(0)2(dba)3 to be determined at high field (700 MHz). DFT calculations support the experimentally determined major and minor isomeric structures, which show that the major isomer of Pd(0)2(dba)3 possesses bridging dba ligands found exclusively in a s-cis,s-trans conformation. For the minor isomer one of the dba ligands is found exclusively in a s-trans,s-trans conformation. Single crystal X-ray diffraction analysis of Pd(0)2(dba)3·CHCl3 (high-quality data) shows that all three dba ligands are found over two positions. NMR spectroscopic analysis of Pd(0)2(dba-Z)3 reveals that the aryl substituent has a profound effect on the rate of Pd-olefin exchange and the global stability of the complexes in solution. Complexes containing the aryl substituents, 4-CF3, 4-F, 4-t-Bu, 4-hexoxy, 4-OMe, exhibit well-resolved (1)H NMR spectra at 298 K, whereas those containing 3,5-OMe and 3,4,5-OMe exhibit broad spectra. The solid-state structures of three Pd(0)2(dba-Z)3 complexes (4-F, 4-OMe, 3,5-OMe) have been determined by single crystal X-ray diffraction methods, which have been compared with Goodson's X-ray structure of Pd(0)2(dba-4-OH)3.
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Pitz-Paal R, Amin A, Bettzüge M, Eames P, Fabrizi F, Flamant G, Garcia Novo F, Holmes J, Kribus A, van der Laan H, Lopez C, Papagiannakopoulos P, Pihl E, Smith P, Wagner HJ. Concentrating solar power in Europe, the Middle East and North Africa: achieving its potential. EPJ WEB OF CONFERENCES 2012. [DOI: 10.1051/epjconf/20123303004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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