17 results
Weathering of Chlorite and Vermiculite in Ultramafic Rocks of Cabo Ortegal, Northwestern Spain
- P. Buurman, E. L. Meijer, J. H. van Wijck
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- Journal:
- Clays and Clay Minerals / Volume 36 / Issue 3 / June 1988
- Published online by Cambridge University Press:
- 02 April 2024, pp. 263-269
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Chloritic veins in serpentinite and their weathering products were analyzed by X-ray powder diffraction (XRD) and X-ray fluorescence spectrometry (XRF). Chlorite formed during the Hercynian-age orogenesis had apparently been partly transformed to high-charge vermiculite during subsequent metamorphism of the rocks. The idealized structural formulae for these minerals are (Al1.9Fe3+0.2Fe2+0.4Mg9.2Cr0.2)(Si5.8Al2.2)O20(OH)16 and X1.3(Fe3+0.7Fe2+0.1Mg5.2Ni0.1)(Si5.8Al2.2)O20(OH)4, respectively. This transformation appears to have taken place by the removal of the hydroxy-interlayer from the chlorite without major effect on the rest of the structure. It is not clear whether other hydroxy-interlayered vermiculites containing less tetrahedral aluminum were intermediate weathering products or inherited minerals. The ultimate weathering product of chlorite and vermiculites was a Fe3+-rich smectite, which probably formed by precipitation from solution.
Oncological and functional outcomes in T3 and T4 laryngeal cancer patients: choice for larynx preservation or total laryngectomy based on expected laryngeal function
- Arman Nobacht, Tineke W H Meijer, Sjoukje F Oosting, Bert van der Vegt, Jan Wedman, György B Halmos, Boudewijn E C Plaat
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- Journal:
- The Journal of Laryngology & Otology , First View
- Published online by Cambridge University Press:
- 18 January 2024, pp. 1-7
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Objective
To determine oncological and functional outcomes in patients with T3 and T4 laryngeal carcinoma, in which choice of treatment was based on expected laryngeal function and not T classification.
MethodsOncological outcomes (disease-specific survival and overall survival) as well as functional outcomes (larynx preservation and functional larynx preservation) were analysed.
ResultsIn 130 T3 and 59 T4 patients, there was no difference in disease-specific survival or overall survival rates after radiotherapy (RT) (107 patients), chemoradiotherapy (36 patients) and total laryngectomy (46 patients). The five-year disease-specific survival rates were 83 per cent after RT, 78 per cent after chemoradiotherapy and 69 per cent after total laryngectomy, whereas overall survival rates were 62, 54 and 60 per cent, respectively. Five-year larynx preservation and functional larynx preservation rates were comparable for RT (79 and 66 per cent, respectively) and chemoradiotherapy (86 and 62 per cent, respectively).
ConclusionThere is no difference in oncological outcome after (chemo)radiotherapy or total laryngectomy in T3 and T4 laryngeal carcinoma patients whose choice of treatment was based on expected laryngeal function.
Associations in time between salivary cortisol and emotions in depressed patients and controls
- A.-S. Koning, S. H. Booij, O. C. Meijer, H. Riese, E. J. Giltay
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- Journal:
- European Psychiatry / Volume 66 / Issue S1 / March 2023
- Published online by Cambridge University Press:
- 19 July 2023, p. S159
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Introduction
Depression can be understood as a complex dynamic system, where depressive symptoms can directly affect each other. Knowledge on this symptom-symptom interaction is still scarce and is likely to differ between individuals. The hypothalamic-pituitary-adrenal (HPA) axis is often implicated in depression, with hypercortisolism and impaired glucocorticoid receptor-mediated feedback inhibition being commonly reported. High salivary cortisol levels may reflect a reaction to symptoms, or may rather be a cause, effectively ‘binding’ symptoms.
ObjectivesWe aimed to analyze the temporal interplay between salivary cortisol and emotions in depressed patients and controls by using the novel Dynamic Time Warp analysis (DTW) approach.
MethodsThe ‘Mood and movement in daily life’ (MOOVD) study consisted of 30 pair-matched (15 depressed and 15 control) participants. Salivary cortisol was collected three times a day for 30 days, resulting in 90 measurements per individual. At the same moments, participants completed questionnaires on an electronic diary, which included different momentary positive (PA) and negative (NA) affect items. The dynamic interplay between salivary cortisol and affect were analyzed by DTW, which extends momentarily associations to include one earlier and one later time point, in both undirected and directed analyses.
ResultsIndividual networks differed substantially within groups. At the group level, undirected and directed network analyses showed differences between depressed patients and controls. In undirected analysis, connectivity of PA items was comparable between depressed patients and controls, but the NA items showed a less dense network in depressed patients. Directed DTW analyses indicated (p = 0.07) that increases in salivary cortisol preceded that of some NA items (e.g., tiredness) in controls, but tended to follow upon NA item increase (e.g., not feeling appreciated) in depressed patients.
ConclusionsAt the group level, connectiveness between NA items was substantially weaker in depressed patients compared to controls. As in complex systems strong internal connectivity facilitates “critical transitions” to different states, this may reflect (or explain) the persistence of a chronically depressed state. We preliminary conclude that high salivary cortisol in depression may be a consequence of NA, rather than a cause. Replication of these first exploratory findings are needed.
Disclosure of InterestNone Declared
Contributors
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- By Mitchell Aboulafia, Frederick Adams, Marilyn McCord Adams, Robert M. Adams, Laird Addis, James W. Allard, David Allison, William P. Alston, Karl Ameriks, C. Anthony Anderson, David Leech Anderson, Lanier Anderson, Roger Ariew, David Armstrong, Denis G. Arnold, E. J. Ashworth, Margaret Atherton, Robin Attfield, Bruce Aune, Edward Wilson Averill, Jody Azzouni, Kent Bach, Andrew Bailey, Lynne Rudder Baker, Thomas R. Baldwin, Jon Barwise, George Bealer, William Bechtel, Lawrence C. Becker, Mark A. Bedau, Ernst Behler, José A. Benardete, Ermanno Bencivenga, Jan Berg, Michael Bergmann, Robert L. Bernasconi, Sven Bernecker, Bernard Berofsky, Rod Bertolet, Charles J. Beyer, Christian Beyer, Joseph Bien, Joseph Bien, Peg Birmingham, Ivan Boh, James Bohman, Daniel Bonevac, Laurence BonJour, William J. Bouwsma, Raymond D. Bradley, Myles Brand, Richard B. Brandt, Michael E. Bratman, Stephen E. Braude, Daniel Breazeale, Angela Breitenbach, Jason Bridges, David O. Brink, Gordon G. Brittan, Justin Broackes, Dan W. Brock, Aaron Bronfman, Jeffrey E. Brower, Bartosz Brozek, Anthony Brueckner, Jeffrey Bub, Lara Buchak, Otavio Bueno, Ann E. Bumpus, Robert W. Burch, John Burgess, Arthur W. Burks, Panayot Butchvarov, Robert E. Butts, Marina Bykova, Patrick Byrne, David Carr, Noël Carroll, Edward S. Casey, Victor Caston, Victor Caston, Albert Casullo, Robert L. Causey, Alan K. L. Chan, Ruth Chang, Deen K. Chatterjee, Andrew Chignell, Roderick M. Chisholm, Kelly J. Clark, E. J. Coffman, Robin Collins, Brian P. Copenhaver, John Corcoran, John Cottingham, Roger Crisp, Frederick J. Crosson, Antonio S. Cua, Phillip D. Cummins, Martin Curd, Adam Cureton, Andrew Cutrofello, Stephen Darwall, Paul Sheldon Davies, Wayne A. Davis, Timothy Joseph Day, Claudio de Almeida, Mario De Caro, Mario De Caro, John Deigh, C. F. Delaney, Daniel C. Dennett, Michael R. DePaul, Michael Detlefsen, Daniel Trent Devereux, Philip E. Devine, John M. Dillon, Martin C. Dillon, Robert DiSalle, Mary Domski, Alan Donagan, Paul Draper, Fred Dretske, Mircea Dumitru, Wilhelm Dupré, Gerald Dworkin, John Earman, Ellery Eells, Catherine Z. Elgin, Berent Enç, Ronald P. Endicott, Edward Erwin, John Etchemendy, C. Stephen Evans, Susan L. Feagin, Solomon Feferman, Richard Feldman, Arthur Fine, Maurice A. Finocchiaro, William FitzPatrick, Richard E. Flathman, Gvozden Flego, Richard Foley, Graeme Forbes, Rainer Forst, Malcolm R. Forster, Daniel Fouke, Patrick Francken, Samuel Freeman, Elizabeth Fricker, Miranda Fricker, Michael Friedman, Michael Fuerstein, Richard A. Fumerton, Alan Gabbey, Pieranna Garavaso, Daniel Garber, Jorge L. A. Garcia, Robert K. Garcia, Don Garrett, Philip Gasper, Gerald Gaus, Berys Gaut, Bernard Gert, Roger F. Gibson, Cody Gilmore, Carl Ginet, Alan H. Goldman, Alvin I. Goldman, Alfonso Gömez-Lobo, Lenn E. Goodman, Robert M. Gordon, Stefan Gosepath, Jorge J. E. Gracia, Daniel W. Graham, George A. Graham, Peter J. Graham, Richard E. Grandy, I. Grattan-Guinness, John Greco, Philip T. Grier, Nicholas Griffin, Nicholas Griffin, David A. Griffiths, Paul J. Griffiths, Stephen R. Grimm, Charles L. Griswold, Charles B. Guignon, Pete A. Y. Gunter, Dimitri Gutas, Gary Gutting, Paul Guyer, Kwame Gyekye, Oscar A. Haac, Raul Hakli, Raul Hakli, Michael Hallett, Edward C. Halper, Jean Hampton, R. James Hankinson, K. R. Hanley, Russell Hardin, Robert M. Harnish, William Harper, David Harrah, Kevin Hart, Ali Hasan, William Hasker, John Haugeland, Roger Hausheer, William Heald, Peter Heath, Richard Heck, John F. Heil, Vincent F. Hendricks, Stephen Hetherington, Francis Heylighen, Kathleen Marie Higgins, Risto Hilpinen, Harold T. Hodes, Joshua Hoffman, Alan Holland, Robert L. Holmes, Richard Holton, Brad W. Hooker, Terence E. Horgan, Tamara Horowitz, Paul Horwich, Vittorio Hösle, Paul Hoβfeld, Daniel Howard-Snyder, Frances Howard-Snyder, Anne Hudson, Deal W. Hudson, Carl A. Huffman, David L. Hull, Patricia Huntington, Thomas Hurka, Paul Hurley, Rosalind Hursthouse, Guillermo Hurtado, Ronald E. Hustwit, Sarah Hutton, Jonathan Jenkins Ichikawa, Harry A. Ide, David Ingram, Philip J. Ivanhoe, Alfred L. Ivry, Frank Jackson, Dale Jacquette, Joseph Jedwab, Richard Jeffrey, David Alan Johnson, Edward Johnson, Mark D. Jordan, Richard Joyce, Hwa Yol Jung, Robert Hillary Kane, Tomis Kapitan, Jacquelyn Ann K. Kegley, James A. Keller, Ralph Kennedy, Sergei Khoruzhii, Jaegwon Kim, Yersu Kim, Nathan L. King, Patricia Kitcher, Peter D. Klein, E. D. Klemke, Virginia Klenk, George L. Kline, Christian Klotz, Simo Knuuttila, Joseph J. Kockelmans, Konstantin Kolenda, Sebastian Tomasz Kołodziejczyk, Isaac Kramnick, Richard Kraut, Fred Kroon, Manfred Kuehn, Steven T. Kuhn, Henry E. Kyburg, John Lachs, Jennifer Lackey, Stephen E. Lahey, Andrea Lavazza, Thomas H. Leahey, Joo Heung Lee, Keith Lehrer, Dorothy Leland, Noah M. Lemos, Ernest LePore, Sarah-Jane Leslie, Isaac Levi, Andrew Levine, Alan E. Lewis, Daniel E. Little, Shu-hsien Liu, Shu-hsien Liu, Alan K. L. Chan, Brian Loar, Lawrence B. Lombard, John Longeway, Dominic McIver Lopes, Michael J. Loux, E. J. Lowe, Steven Luper, Eugene C. Luschei, William G. Lycan, David Lyons, David Macarthur, Danielle Macbeth, Scott MacDonald, Jacob L. Mackey, Louis H. Mackey, Penelope Mackie, Edward H. Madden, Penelope Maddy, G. B. Madison, Bernd Magnus, Pekka Mäkelä, Rudolf A. Makkreel, David Manley, William E. Mann (W.E.M.), Vladimir Marchenkov, Peter Markie, Jean-Pierre Marquis, Ausonio Marras, Mike W. Martin, A. P. Martinich, William L. McBride, David McCabe, Storrs McCall, Hugh J. McCann, Robert N. McCauley, John J. McDermott, Sarah McGrath, Ralph McInerny, Daniel J. McKaughan, Thomas McKay, Michael McKinsey, Brian P. McLaughlin, Ernan McMullin, Anthonie Meijers, Jack W. Meiland, William Jason Melanson, Alfred R. Mele, Joseph R. Mendola, Christopher Menzel, Michael J. Meyer, Christian B. Miller, David W. Miller, Peter Millican, Robert N. Minor, Phillip Mitsis, James A. Montmarquet, Michael S. Moore, Tim Moore, Benjamin Morison, Donald R. Morrison, Stephen J. Morse, Paul K. Moser, Alexander P. D. Mourelatos, Ian Mueller, James Bernard Murphy, Mark C. Murphy, Steven Nadler, Jan Narveson, Alan Nelson, Jerome Neu, Samuel Newlands, Kai Nielsen, Ilkka Niiniluoto, Carlos G. Noreña, Calvin G. Normore, David Fate Norton, Nikolaj Nottelmann, Donald Nute, David S. Oderberg, Steve Odin, Michael O’Rourke, Willard G. Oxtoby, Heinz Paetzold, George S. Pappas, Anthony J. Parel, Lydia Patton, R. P. Peerenboom, Francis Jeffry Pelletier, Adriaan T. Peperzak, Derk Pereboom, Jaroslav Peregrin, Glen Pettigrove, Philip Pettit, Edmund L. Pincoffs, Andrew Pinsent, Robert B. Pippin, Alvin Plantinga, Louis P. Pojman, Richard H. Popkin, John F. Post, Carl J. Posy, William J. Prior, Richard Purtill, Michael Quante, Philip L. Quinn, Philip L. Quinn, Elizabeth S. Radcliffe, Diana Raffman, Gerard Raulet, Stephen L. Read, Andrews Reath, Andrew Reisner, Nicholas Rescher, Henry S. Richardson, Robert C. Richardson, Thomas Ricketts, Wayne D. Riggs, Mark Roberts, Robert C. Roberts, Luke Robinson, Alexander Rosenberg, Gary Rosenkranz, Bernice Glatzer Rosenthal, Adina L. Roskies, William L. Rowe, T. M. Rudavsky, Michael Ruse, Bruce Russell, Lilly-Marlene Russow, Dan Ryder, R. M. Sainsbury, Joseph Salerno, Nathan Salmon, Wesley C. Salmon, Constantine Sandis, David H. Sanford, Marco Santambrogio, David Sapire, Ruth A. Saunders, Geoffrey Sayre-McCord, Charles Sayward, James P. Scanlan, Richard Schacht, Tamar Schapiro, Frederick F. Schmitt, Jerome B. Schneewind, Calvin O. Schrag, Alan D. Schrift, George F. Schumm, Jean-Loup Seban, David N. Sedley, Kenneth Seeskin, Krister Segerberg, Charlene Haddock Seigfried, Dennis M. Senchuk, James F. Sennett, William Lad Sessions, Stewart Shapiro, Tommie Shelby, Donald W. Sherburne, Christopher Shields, Roger A. Shiner, Sydney Shoemaker, Robert K. Shope, Kwong-loi Shun, Wilfried Sieg, A. John Simmons, Robert L. Simon, Marcus G. Singer, Georgette Sinkler, Walter Sinnott-Armstrong, Matti T. Sintonen, Lawrence Sklar, Brian Skyrms, Robert C. Sleigh, Michael Anthony Slote, Hans Sluga, Barry Smith, Michael Smith, Robin Smith, Robert Sokolowski, Robert C. Solomon, Marta Soniewicka, Philip Soper, Ernest Sosa, Nicholas Southwood, Paul Vincent Spade, T. L. S. Sprigge, Eric O. Springsted, George J. Stack, Rebecca Stangl, Jason Stanley, Florian Steinberger, Sören Stenlund, Christopher Stephens, James P. Sterba, Josef Stern, Matthias Steup, M. A. Stewart, Leopold Stubenberg, Edith Dudley Sulla, Frederick Suppe, Jere Paul Surber, David George Sussman, Sigrún Svavarsdóttir, Zeno G. Swijtink, Richard Swinburne, Charles C. Taliaferro, Robert B. Talisse, John Tasioulas, Paul Teller, Larry S. Temkin, Mark Textor, H. S. Thayer, Peter Thielke, Alan Thomas, Amie L. Thomasson, Katherine Thomson-Jones, Joshua C. Thurow, Vzalerie Tiberius, Terrence N. Tice, Paul Tidman, Mark C. Timmons, William Tolhurst, James E. Tomberlin, Rosemarie Tong, Lawrence Torcello, Kelly Trogdon, J. D. Trout, Robert E. Tully, Raimo Tuomela, John Turri, Martin M. Tweedale, Thomas Uebel, Jennifer Uleman, James Van Cleve, Harry van der Linden, Peter van Inwagen, Bryan W. Van Norden, René van Woudenberg, Donald Phillip Verene, Samantha Vice, Thomas Vinci, Donald Wayne Viney, Barbara Von Eckardt, Peter B. M. Vranas, Steven J. Wagner, William J. Wainwright, Paul E. Walker, Robert E. Wall, Craig Walton, Douglas Walton, Eric Watkins, Richard A. Watson, Michael V. Wedin, Rudolph H. Weingartner, Paul Weirich, Paul J. Weithman, Carl Wellman, Howard Wettstein, Samuel C. Wheeler, Stephen A. White, Jennifer Whiting, Edward R. Wierenga, Michael Williams, Fred Wilson, W. Kent Wilson, Kenneth P. Winkler, John F. Wippel, Jan Woleński, Allan B. Wolter, Nicholas P. Wolterstorff, Rega Wood, W. Jay Wood, Paul Woodruff, Alison Wylie, Gideon Yaffe, Takashi Yagisawa, Yutaka Yamamoto, Keith E. Yandell, Xiaomei Yang, Dean Zimmerman, Günter Zoller, Catherine Zuckert, Michael Zuckert, Jack A. Zupko (J.A.Z.)
- Edited by Robert Audi, University of Notre Dame, Indiana
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- The Cambridge Dictionary of Philosophy
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- 05 August 2015
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- 27 April 2015, pp ix-xxx
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Adapted cognitive–behavioural therapy required for targeting negative symptoms in schizophrenia: meta-analysis and meta-regression
- E. Velthorst, M. Koeter, M. van der Gaag, D. H. Nieman, A.-K. J. Fett, F. Smit, A. B. P. Staring, C. Meijer, L. de Haan
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- Psychological Medicine / Volume 45 / Issue 3 / February 2015
- Published online by Cambridge University Press:
- 22 May 2014, pp. 453-465
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Background
There is an increasing interest in cognitive–behavioural therapy (CBT) interventions targeting negative symptoms in schizophrenia. To date, CBT trials primarily focused on positive symptoms and investigated change in negative symptoms only as a secondary outcome. To enhance insight into factors contributing to improvement of negative symptoms, and to identify subgroups of patients that may benefit most from CBT directed at ameliorating negative symptoms, we reviewed all available evidence on these outcomes.
MethodA systematic search of the literature was conducted in PsychInfo, PubMed and the Cochrane register to identify randomized controlled trials reporting on the impact of CBT interventions on negative symptoms in schizophrenia. Random-effects meta-analyses were performed on end-of-treatment, short-term and long-term changes in negative symptoms.
ResultsA total of 35 publications covering 30 trials in 2312 patients, published between 1993 and 2013, were included. Our results showed studies’ pooled effect on symptom alleviation to be small [Hedges’ g = 0.093, 95% confidence interval (CI) −0.028 to 0.214, p = 0.130] and heterogeneous (Q = 73.067, degrees of freedom = 29, p < 0.001, τ2 = 0.081, I2 = 60.31) in studies with negative symptoms as a secondary outcome. Similar results were found for studies focused on negative symptom reduction (Hedges’ g = 0.157, 95% CI −0.10 to 0.409, p = 0.225). Meta-regression revealed that stronger treatment effects were associated with earlier year of publication, lower study quality and with CBT provided individually (as compared with group-based).
ConclusionsThe co-occurring beneficial effect of conventional CBT on negative symptoms found in older studies was not supported by more recent studies. It is now necessary to further disentangle effective treatment ingredients of older studies in order to guide the development of future CBT interventions aimed at negative symptom reduction.
Cognitive functioning associated with stimulant use in patients with non-affective psychosis, their unaffected siblings and healthy controls
- F. J. van der Meer, J. H. Meijer, C. J. Meijer, W. van den Brink, E. Velthorst
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- Psychological Medicine / Volume 44 / Issue 9 / July 2014
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- 22 November 2013, pp. 1901-1911
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Background
Little is known about the effect of stimulant use (amphetamines, cocaine, ecstasy) on cognitive functioning in schizophrenia patients. The current study examined (1) whether recency and frequency of stimulant use is associated with cognitive functioning and (2) whether these associations differ between psychotic patients, their unaffected siblings and controls.
MethodParticipants completed a comprehensive cognitive test battery. Stimulant use was assessed by urinalysis and by the Composite International Diagnostic Interview (CIDI). Using random effects regression models, the main effects of Stimulant Use and the interaction with Diagnostic Status on cognitive functioning were assessed.
ResultsThe interaction term between Stimulant Use and Diagnostic Status was not significant for any of the cognitive outcome variables, indicating similar effects of stimulant use in all three groups. Recent stimulant users showed more errors deficit in verbal learning in comparison to never users (Cohen's d = −0.60, p < 0.005). Lifetime frequent stimulant use was significantly associated with worse immediate and delayed verbal recall, working memory and acquired knowledge (Cohen's d = −0.22 to −0.29, p < 0.005). Lifetime infrequent stimulant use was not associated with significant cognitive alterations in comparison to never use.
ConclusionsThe presence of cognitive deficits associated with lifetime stimulant use is dependent on the frequency of use, with no observed deficits in infrequent users and modest negative effects in frequent users.
Adjusted prognostic association of depression following myocardial infarction with mortality and cardiovascular events: individual patient data meta-analysis
- A. Meijer, H. J. Conradi, E. H. Bos, M. Anselmino, R. M. Carney, J. Denollet, F. Doyle, K. E. Freedland, S. L. Grace, S. H. Hosseini, D. A. Lane, L. Pilote, K. Parakh, C. Rafanelli, H. Sato, R. P. Steeds, C. Welin, P. de Jonge
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- Journal:
- The British Journal of Psychiatry / Volume 203 / Issue 2 / August 2013
- Published online by Cambridge University Press:
- 02 January 2018, pp. 90-102
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- August 2013
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Background
The association between depression after myocardial infarction and increased risk of mortality and cardiac morbidity may be due to cardiac disease severity.
AimsTo combine original data from studies on the association between post-infarction depression and prognosis into one database, and to investigate to what extent such depression predicts prognosis independently of disease severity.
MethodAn individual patient data meta-analysis of studies was conducted using multilevel, multivariable Cox regression analyses.
ResultsSixteen studies participated, creating a database of 10 175 post-infarction cases. Hazard ratios for post-infarction depression were 1.32 (95% CI 1.26–1.38, P<0.001) for all-cause mortality and 1.19 (95% CI 1.14–1.24, P<0.001) for cardiovascular events. Hazard ratios adjusted for disease severity were attenuated by 28% and 25% respectively.
ConclusionsThe association between depression following myocardial infarction and prognosis is attenuated after adjustment for cardiac disease severity. Still, depression remains independently associated with prognosis, with a 22% increased risk of all-cause mortality and a 13% increased risk of cardiovascular events per standard deviation in depression z-score.
The Netherlands Twin Register Biobank: A Resource for Genetic Epidemiological Studies
- Gonneke Willemsen, Eco J. C. de Geus, Meike Bartels, C. E. M. Toos van Beijsterveldt, Andy I. Brooks, G. Frederique Estourgie-van Burk, Douglas A. Fugman, Chantal Hoekstra, Jouke-Jan Hottenga, Kees Kluft, Piet Meijer, Grant W. Montgomery, Patrizia Rizzu, David Sondervan, August B. Smit, Sabine Spijker, H. Eka D. Suchiman, Jay A. Tischfield, Thomas Lehner, P. Eline Slagboom, Dorret I. Boomsma
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- Twin Research and Human Genetics / Volume 13 / Issue 3 / 01 June 2010
- Published online by Cambridge University Press:
- 21 February 2012, pp. 231-245
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In 2004 the Netherlands Twin Register (NTR) started a large scale biological sample collection in twin families to create a resource for genetic studies on health, lifestyle and personality. Between January 2004 and July 2008, adult participants from NTR research projects were invited into the study. During a home visit between 7:00 and 10:00 am, fasting blood and morning urine samples were collected. Fertile women were bled on day 2–4 of the menstrual cycle, or in their pill-free week. Biological samples were collected for DNA isolation, gene expression studies, creation of cell lines and for biomarker assessment. At the time of blood sampling, additional phenotypic information concerning health, medication use, body composition and smoking was collected. Of the participants contacted, 69% participated. Blood and urine samples were collected in 9,530 participants (63% female, average age 44.4 (SD 15.5) years) from 3,477 families. Lipid profile, glucose, insulin, HbA1c, haematology, CRP, fibrinogen, liver enzymes and creatinine have been assessed. Longitudinal survey data on health, personality and lifestyle are currently available for 90% of all participants. Genome-wide SNP data are available for 3,524 participants, with additional genotyping ongoing. The NTR biobank, combined with the extensive phenotypic information available within the NTR, provides a valuable resource for the study of genetic determinants of individual differences in mental and physical health. It offers opportunities for DNA-based and gene expression studies as well as for future metabolomic and proteomic projects.
Diffuse-interface modelling of droplet impact
- V. V. KHATAVKAR, P. D. ANDERSON, P. C. DUINEVELD, H. E. H. MEIJER
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- Journal of Fluid Mechanics / Volume 581 / 25 June 2007
- Published online by Cambridge University Press:
- 22 May 2007, pp. 97-127
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The impact of micron-size drops on a smooth, flat, chemically homogeneous solid surface is studied using a diffuse-interface model (DIM). The model is based on the Cahn–Hilliard theory that couples thermodynamics with hydrodynamics, and is extended to include non-90° contact angles. The (axisymmetric) equations are numerically solved using a combination of finite- and spectral-element methods. The influence of various process and material parameters such as impact velocity, droplet diameter, viscosity, surface tension and wettability on the impact behaviour of drops is investigated. Relevant dimensionless parameters are defined and, depending on the values of the Reynolds number, the Weber number and the contact angle, which for the cases considered here range from 1.3 to 130, 0.43 to 150 and 45° to 135°, respectively, the model predicts the spreading of a droplet with or without recoil or even rebound of the droplet, totally or partially, from the solid surface. The wettability significantly affects the impact behaviour and this is particularly demonstrated with an impact at Re = 130 and We = 1.5, where for θ < 60° the droplet oscillates a few times before attaining equilibrium while for θ ≥ 60° partial rebound of the droplet occurs, i.e. the droplet breaks into two unequal sized drops. The size of the part that remains in contact with the solid surface progressively decreases with increasing θ until at a value θ ≈ 120° a transition to total rebound happens. When the droplet rebounds totally, it has a top-heavy shape.
Capillary spreading of a droplet in the partially wetting regime using a diffuse-interface model
- V. V. KHATAVKAR, P. D. ANDERSON, H. E. H. MEIJER
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- Journal:
- Journal of Fluid Mechanics / Volume 572 / February 2007
- Published online by Cambridge University Press:
- 23 January 2007, pp. 367-387
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The spreading of a liquid droplet on a smooth solid surface in the partially wetting regime is studied using a diffuse-interface model based on the Cahn--Hilliard theory. The model is extended to include non-90 contact angles. The diffuse-interface model considers the ambient fluid displaced by the droplet while spreading as a liquid. The governing equations of the model for the axisymmetric case are solved numerically using a finite-spectral-element method. The viscosity of the ambient fluid is found to affect the time scale of spreading, but the general spreading behaviour remains unchanged. The wettability expressed in terms of the equilibrium contact angle is seen to influence the spreading kinetics from the early stages of spreading. The results show agreement with the experimental data reported in the literature.
Axisymmetric boundary integral simulations of film drainage between two viscous drops
- P. J. A. JANSSEN, P. D. ANDERSON, G. W. M. PETERS, H. E. H. MEIJER
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- Journal:
- Journal of Fluid Mechanics / Volume 567 / 25 November 2006
- Published online by Cambridge University Press:
- 19 October 2006, pp. 65-90
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Film drainage between two drops with viscosity equal to that of the matrix fluid is studied using a numerical method that can capture both the external problem of two touching drops and the inner problem of pressure-driven local film drainage, without assumptions about the dimensions of the film or the use of lubrication approximations. We use a non-singular boundary integral method that has sufficient stability and accuracy to simulate film thicknesses down to and smaller than $10^{-4}$ times the undeformed drop radius. After validation of the method we investigate the validity of various results obtained from simple film-drainage models and asymptotic theories. Our results for buoyancy-driven collisions are in agreement with a recently developed asymptotic theory. External-flow-driven collisions are different from buoyancy-driven collisions, which means that the internal circulation inside the drop plays a significant role in film drainage, even for small capillary numbers, as has been recently shown (Nemer et al., Phys. Rev. Lett., vol. 92, 2004, 114501). Despite that, we find excellent correspondence with simple drainage models when considering the drainage time only.
Supramolecular Chemistry at the Liquid/Solid Interface
- Steven De Feyter, Hiroshi Uji-i, Atsushi Miura, Wael Mamdouh, Jian Zhang, Jan van Esch, Ben Feringa, A. P. H. J. Schenning, E. W. Meijer, Frank Wuerthner, Frans De Schryver
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- Journal:
- MRS Online Proceedings Library Archive / Volume 901 / 2005
- Published online by Cambridge University Press:
- 26 February 2011, 0901-Ra20-01
- Print publication:
- 2005
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The liquid/solid interface provides an ideal environment to investigate self-assembly phenomena and scanning tunneling microscopy (STM) is the preferred methodology to probe the structure and the properties of physisorbed monolayers on the nanoscale. Physisorbed monolayers are of relevance in areas such as lubrication, patterning of surfaces on the nanoscale, and thin film based organic electronic devices, to name a few. It's important to gain insight in the factors which control the ordering of molecules at the liquid/solid interface in view of the targeted properties. STM provides detailed insight into the importance of molecule-substrate (epitaxy) and molecule-molecule interactions to direct the ordering of both achiral and chiral molecules on the atomically flat surface. The electronic properties of the self-assembled physisorbed molecules can be probed by taking advantage of the operation principle of STM, revealing spatially resolved intramolecular differences within these physisorbed molecules.
Diffuse-interface modelling of thermocapillary flow instabilities in a Hele-Shaw cell
- M. VERSCHUEREN, F. N. VAN DE VOSSE, H. E. H. MEIJER
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- Journal:
- Journal of Fluid Mechanics / Volume 434 / 10 May 2001
- Published online by Cambridge University Press:
- 22 June 2001, pp. 153-166
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In this paper we present the results of a diffuse-interface model for thermocapillary or Marangoni flow in a Hele-Shaw cell. We use a Galerkin-type spectral element discretization, based on Gauss–Lobatto quadrature, for numerical implementation of the governing equations resulting from the diffuse-interface model. The results are compared to classical results for a linear and circular fixed interface. It is found that the diffuse-interface solution converges to the classical solution in the sharp-interface limit. The results are sufficiently accurate if the interfacial thickness is only small compared to the size of the thermocapillary boundary layer, even if the interfacial thickness used is much larger than the real interfacial thickness. We also consider freely movable interfaces with a temperature gradient perpendicular to the interface. It will be shown that this situation can lead to a destabilizing Marangoni convection.
Analysis of mixing in three-dimensional time-periodic cavity flows
- P. D. ANDERSON, O. S. GALAKTIONOV, G. W. M. PETERS, F. N. VAN DE VOSSE, H. E. H. MEIJER
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- Journal:
- Journal of Fluid Mechanics / Volume 386 / 10 May 1999
- Published online by Cambridge University Press:
- 10 May 1999, pp. 149-166
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A method to locate periodic structures in general three-dimensional Stokes flows with time-periodic boundary conditions is presented and applied to mixing cavity flows. Numerically obtained velocity fields and particle tracking schemes are used to provide displacement and stretching fields. From these the location and identification of periodic points can be derived. The presence or absence of these periodic points allows a judgement on the quality of the mixing process. The technique is general and efficient, and applicable to mixing flows for which no analytical velocity field is available (the case for all three-dimensional flows considered in this paper). Results are presented for three different mixing protocols in a three-dimensional time-periodic cavity flow, serving as an accessible test case for the methods developed. A major result is that periodic lines are obtained for these three-dimensional flows. These lines can be complex in geometry and their nature can change along a line from hyperbolic to elliptic. They can serve as practical criteria in the optimization of three-dimensional mixing processes.
The effect of surfactant on the stability of a fluid filament embedded in a viscous fluid
- S. HANSEN, G. W. M. PETERS, H. E. H. MEIJER
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- Journal:
- Journal of Fluid Mechanics / Volume 382 / 10 March 1999
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- 10 March 1999, pp. 331-349
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The effect of surfactant on the breakup of a viscous filament, initially at rest, surrounded by another viscous fluid is studied using linear stability analysis. The role of the surfactant is characterized by the elasticity number – a high elasticity number implies that surfactant is important. As expected, the surfactant slows the growth rate of disturbances. The influence of surfactant on the dominant wavenumber is less trivial. In the Stokes regime, the dominant wavenumber for most viscosity ratios increases with the elasticity number; for filament to matrix viscosity ratios ranging from about 0.03 to 0.4, the dominant wavenumber decreases when the elasticity number increases. Interestingly, a surfactant does not affect the stability of a filament when the surface tension (or Reynolds) number is very large.
Long-term effect of physical activity on energy balance and body composition
- Klaas R. Westerterp, Gerwin A. L. Meijer, Eugene M. E. Janssen, Wim H. M. Saris, Foppe Ten Hoor
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- Journal:
- British Journal of Nutrition / Volume 68 / Issue 1 / July 1992
- Published online by Cambridge University Press:
- 09 March 2007, pp. 21-30
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- July 1992
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We studied the effect of an increase in physical activity on energy balance and body composition without interfering with energy intake (EI). Sixteen women and sixteen men, aged 28–41 years, body mass index 19.4–26.4 kg/m2, not participating in any sport before the start of the experiment, prepared to run a half-marathon competition after 44 weeks. Measurements of body composition, EI and energy expenditure (EE) were performed before (0 weeks), and 8, 20, and 40 weeks after the start of training. Body composition was measured with hydrodensitometry and isotope dilution, and EI with a 7 d dietary record. EE was measured overnight in a respiration chamber (sleeping metabolic rate (SMR)) and in a number of subjects over 2-week intervals with doubly-labelled water (average daily metabolic rate (ADMR)). ADMR showed an average increase of 30% in both sexes from the start of training onwards while SMR tended to decrease. EI showed a tendency to drop from week 20 to week 40 in the men and a tendency to increase from week 20 to week 40 in the women. Body mass (BM) did not change in both sexes until the observation at 40 weeks when the median value of the change in men was –1.0kg (P < 0.01; Wilcoxon signed-rank) while the corresponding change of –0.9 kg in the women was not statistically significant. Body composition changes were most pronounced in men as well. Based on changes in BM, body volume and total body water, men lost 3.8 kg fat mass (FM) (P < 0.001; Wilcoxon signed-rank) and gained 1.6 kg protein mass (P < 0.01; Wilcoxon signed-rank) while the corresponding changes in women were 2.0 kg (P < 0.05; Wilcoxon signed-rank) and 1.2 kg (P < 0.05; Wilcoxon signed-rank). In men the loss of FM was positively correlated with the initial percentage body fat (Pearson r 0.92, P < 0.001). In conclusion, body fat can be reduced by physical activity although women tend to compensate for the increased EE with an increased EI, resulting in a smaller effect on BM and FM compared with men.
Laser Deposition, Vibrational Spectroscopy, NMR Spectroscopy and Stm Imaging of C60 and C70
- G. Meijer, D. S. Bethune, W. C. Tang, H. J. Rosen, R. D. Johnson, R. J. Wilson, D. D. Chambliss, W. G. Golden, H. Seki, M. S. De Vries, C. A. Brown, J. R. Salem, H. E. Hunziker, H. R. Wendt
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- Journal:
- MRS Online Proceedings Library Archive / Volume 206 / 1990
- Published online by Cambridge University Press:
- 28 February 2011, 619
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- 1990
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We recently demonstrated that C60 and C70, as well as other fullerenes, can be deposited and accumulated on surfaces using laser ablation of graphite in an Inert gas atmosphere. After learning of the work of Krätschmer et al. indicating the presence of C60 in carbon soot, we showed that samples consisting almost exclusively of C60 and C70 can be sublimed from such soot. Vibrational Raman spectra of C60 and C70 were obtained from these samples. The C60 spectrum Is consistent with the calculated spectrum of Buckmlnsterfullerene, and the strongest three lines can be assigned on the basis of frequency and polarization. The NMR spectrum of dissolved C60 was then obtained, and found to consist of a single resonance, establishing the icosahedral symmetry of this molecule. STM images of the C60 molecules on a Au(111) crystal face show that these clusters form hexagonal arrays with an intercluster spacing of 11.0 Å and are mobile at ambient temperature. Distinctly taller species evident in the arrays are believed to be C70 clusters. Vibrational Raman and infrared spectra have also been obtained for separated C60 and C70.