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192 results on '"Körner U"'

1. Single-hole dynamics in the t-J model

Author

Apel, W., Everts, H. -U., and Koerner, U.

Subjects
Condensed Matter - Strongly Correlated Electrons
Abstract

The quasi-particle weight of a single hole in an antiferromagnetic background is studied in the semiclassical approximation. We start from the t-J model, generalize it to arbitrary spin S by employing an appropriate coherent state representation for the hole, and derive an effective action for the dynamics in the long-wavelength low-energy limit. In the same limit, we find an expression for the single-hole Green's function which we evaluate in an 1/S expansion. Our approach has the advantage of being applicable in one and in two dimensions. We find two qualitatively different results in these two cases: while in one dimension our results are compatible with a vanishing quasi-particle weight, this weight is found to be finite in two dimensions, indicating normal quasi-particle behavior of the hole in this last case., Comment: 9 pages, 1 figure

Published
2002
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2. Effective Hamiltonians for holes in antiferromagnets: a new approach to implement forbidden double occupancy

Author

Apel, W., Everts, H. -U., and Koerner, U.

Subjects
Condensed Matter - Strongly Correlated Electrons
Abstract

A coherent state representation for the electrons of ordered antiferromagnets is used to derive effective Hamiltonians for the dynamics of holes in such systems. By an appropriate choice of these states, the constraint of forbidden double occupancy can be implemented rigorously. Using these coherent states, one arrives at a path integral representation of the partition function of the systems, from which the effective Hamiltonians can be read off. We apply this method to the t-J model on the square lattice and on the triangular lattice. In the former case, we reproduce the well-known fermion-boson Hamiltonian for a hole in a collinear antiferromagnet. We demonstrate that our method also works for non-collinear antiferromagnets by calculating the spectrum of a hole in the triangular antiferromagnet in the self-consistent Born approximation and by comparing it with numerically exact results., Comment: 9 pages, Latex, 6 figures

Published
1998
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3. Registered Replication Report: Schooler and Engstler-Schooler (1990)

Author

Alogna, V. K., Attaya, M.K., Aucoin, P., Bahnik, Š., Birch, S., Birt, A. R., Bornstein, B. H., Bouwmeester, S., Brandimonte, M. A., Brown, C., Buswell, K., Carlson, C., Carlson, M., Chu, S., Cislak, A., Colarusso, M., Colloff, M. F., Dellapaolera, K.S., Delvenne, J.-F., Di Domenico, A., Drummond, A., Echterhoff, G., Edlund, J. E., Eggleston, C. M., Fairfield, B., Franco, G., Gabbert, F., Gamblin, B. W., Garry, M., Gentry, R., Gilbert, E. A., Greenberg, D. L., Halberstadt, J., Hall, L., Hancock, P. J. B., Hirsch, D., Holt, G., Jackson, J. C., Jong, J., Kehn, A., Koch, C., Kopietz, R., Körner, U., Kunar, M. A., Lai, C. K., Langton, S. R. H., Leite, F. P., Mammarella, N., Marsh, J. E., McConnaughy, K. A., McCoy, S., McIntyre, A. H., Meissner, C. A., Michael, R.B., Mitchell, A.A., Mugayar-Baldocchi, M., Musselman, R., Ng, C., Nichols, A. L., Nunez, N. L., Palmer, M. A., Pappagianopoulos, J. E., Petro, M. S., Poirier, C. R., Portch, E., Rainsford, M., Rancourt, A., Romig, C., Rubínová, E., Sanson, M., Satchell, L., Sauer, J. D., Schweitzer, K., Shaheed, J., Skelton, F., Sullivan, G. A., Susa, K. J., Swanner, J. K., Thompson, W. B., Todaro, R., Ulatowska, J., Valentine, T., Verkoeijen, P. P. J. L., Vranka, M., Wade, K. A., Was, C. A., Weatherford, D., Wiseman, K., Zaksaite, T., Zuj, D. V., and Zwaan, R. A.

Published
2014

24. How the diagnosis of non-celiac gluten sensitivity (NCGS) should be confirmed: the Salerno experts’ criteria

Author

Catassi, C, Elli, L, Bonaz, B, Bouma, G, Carroccio, A, Castillejo, G, Cellier, C, Cristofori, F, de Magistris, L, Dolinsek, J, Dieterich, W, Francavilla, R, Hadjivassiliou, M, Holtmeier, W, Körner, U, D A, Leffler, K E A, Lundin, Mazzarella, G, C J, Mulder, Pellegrini, N, Rostami, K, Sanders, D, G I, Skodje, Schuppan, D, Ullrich, R, Volta, U, Williams, M, V F, Zevallos, Zopf, Y, and Fasano, A

Subjects
irritable bowel syndrome, diagnosis, non-celiac gluten sensitivity, gastrointestinal symptom rating scale, double-blind placebo-controlled challenge
Published
2015

25. Contribution to Alonga et al (2014). Registered replication report: Schooler & Engstler-Schooler (1990)

Author

Alogna, VK, Attaya, MK, Aucoin, P, Bahník, Š, Birch, S, Bornstein, B, Bouwmeester, S, Brandimonte, MA, Brown, C, Buswell, K, Carlson, C, Carlson, M, Chu, S, Cislak, A, Colarusso, M, Colloff, MF, Dellapaolera, KS, Delvenne, JFCM, Di Domenico, A, Drummond, A, Echterhoff, G, Edlund, JE, Eggleston, CM, Fairfield, B, Franco, G, Gabbert, F, Gamblin, BW, Garry, M, Gentry, R, Gilbert, EA, Greenberg, DL, Halberstadt, J, Hall, L, Hancock, PJB, Hirsch, D, Holt, G, Jackson, JC, Jong, J, Kehn, A, Koch, C, Kopietz, R, Körner, U, Kunar, MA, Lai, CK, Langton, SRH, Leite, FP, Mammarella, N, Marsh, JE, McConnaughy, KA, McCoy, S, McIntyre, AH, Meissner, CA, Michael, RB, Mitchell, AA, Mugayar-Baldocchi, M, Musselman, R, Ng, C, Nichols, AL, Nunez, NL, Palmer, MA, Pappagianopoulos, JE, Petro, MS, Poirier, CR, Portch, E, Rainsford, M, Rancourt, A, Romig, C, Rubínová, E, Sanson, M, Satchell, L, Sauer, JD, Schweitzer, K, Shaheed, J, Skelton, F, Sullivan, GA, Susa, KJ, Swanner, JK, Thompson, WB, Todaro, R, Ulatowska, J, Valentine, T, Verkoeijen, PPJL, Vranka, M, Wade, KA, Was, CA, Weatherford, D, Wiseman, K, Zaksaite, T, Zuj, DV, Zwaan, RA, and Simons, DJ

Abstract

Trying to remember something now typically improves your ability to remember it later. However, after watching a video of a simulated bank robbery, participants who verbally described the robber were 25% worse at identifying the robber in a lineup than were participants who instead listed U.S. states and capitals—this has been termed the “verbal overshadowing” effect (Schooler & Engstler-Schooler, 1990). More recent studies suggested that this effect might be substantially smaller than first reported. Given uncertainty about the effect size, the influence of this finding in the memory literature, and its practical importance for police procedures, we conducted two collections of preregistered direct replications (RRR1 and RRR2) that differed only in the order of the description task and a filler task. In RRR1, when the description task immediately followed the robbery, participants who provided a description were 4% less likely to select the robber than were those in the control condition. In RRR2, when the description was delayed by 20 min, they were 16% less likely to select the robber. These findings reveal a robust verbal overshadowing effect that is strongly influenced by the relative timing of the tasks. The discussion considers further implications of these replications for our understanding of verbal overshadowing.

Published
2014

26. Diagnosis of non-celiac gluten sensitivity (NCGS): The salerno experts’ criteria

Author

Universitat Rovira i Virgili, Catassi C; Elli L; Bonaz B; Bouma G; Carroccio A; Castillejo G; Cellier C; Cristofori F; de Magistris L; Dolinsek J; Dieterich W; Francavilla R; Hadjivassiliou M; Holtmeier W; Körner U; Leffler DA; Lundin KEA; Mazzarella G; Mulder CJ; Pellegrini N; Rostami K; Sanders D; Skodje GI; Schuppan D; Ullrich R; Volta U; Williams M; Zevallos VF; Zopf Y; Fasano A, Universitat Rovira i Virgili, and Catassi C; Elli L; Bonaz B; Bouma G; Carroccio A; Castillejo G; Cellier C; Cristofori F; de Magistris L; Dolinsek J; Dieterich W; Francavilla R; Hadjivassiliou M; Holtmeier W; Körner U; Leffler DA; Lundin KEA; Mazzarella G; Mulder CJ; Pellegrini N; Rostami K; Sanders D; Skodje GI; Schuppan D; Ullrich R; Volta U; Williams M; Zevallos VF; Zopf Y; Fasano A

Abstract

© 2015 by the authors; licensee MDPI, Basel, Switzerland. Non-Celiac Gluten Sensitivity (NCGS) is a syndrome characterized by intestinal and extra-intestinal symptoms related to the ingestion of gluten-containing food, in subjects that are not affected by either celiac disease or wheat allergy. Given the lack of a NCGS biomarker, there is the need for standardizing the procedure leading to the diagnosis confirmation. In this paper we report experts’ recommendations on how the diagnostic protocol should be performed for the confirmation of NCGS. A full diagnostic procedure should assess the clinical response to the gluten-free diet (GFD) and measure the effect of a gluten challenge after a period of treatment with the GFD. The clinical evaluation is performed using a self-administered instrument incorporating a modified version of the Gastrointestinal Symptom Rating Scale. The patient identifies one to three main symptoms that are quantitatively assessed using a Numerical Rating Scale with a score ranging from 1 to 10. The double-blind placebo-controlled gluten challenge (8 g/day) includes a one-week challenge followed by a one-week washout of strict GFD and by the crossover to the second one-week challenge. The vehicle should contain cooked, homogeneously distributed gluten. At least a variation of 30% of one to three main symptoms between the gluten and the placebo challenge should be detected to discriminate a positive from a negative result. The guidelines provided in this paper will help the clinician to reach a firm and positive diagnosis of NCGS and facilitate the comparisons of different studies, if adopted internationally.

Published
2015

29. Registered Replication Report

Author

Alogna, V. K., primary, Attaya, M. K., additional, Aucoin, P., additional, Bahník, Š., additional, Birch, S., additional, Birt, A. R., additional, Bornstein, B. H., additional, Bouwmeester, S., additional, Brandimonte, M. A., additional, Brown, C., additional, Buswell, K., additional, Carlson, C., additional, Carlson, M., additional, Chu, S., additional, Cislak, A., additional, Colarusso, M., additional, Colloff, M. F., additional, Dellapaolera, K. S., additional, Delvenne, J.-F., additional, Di Domenico, A., additional, Drummond, A., additional, Echterhoff, G., additional, Edlund, J. E., additional, Eggleston, C. M., additional, Fairfield, B., additional, Franco, G., additional, Gabbert, F., additional, Gamblin, B. W., additional, Garry, M., additional, Gentry, R., additional, Gilbert, E. A., additional, Greenberg, D. L., additional, Halberstadt, J., additional, Hall, L., additional, Hancock, P. J. B., additional, Hirsch, D., additional, Holt, G., additional, Jackson, J. C., additional, Jong, J., additional, Kehn, A., additional, Koch, C., additional, Kopietz, R., additional, Körner, U., additional, Kunar, M. A., additional, Lai, C. K., additional, Langton, S. R. H., additional, Leite, F. P., additional, Mammarella, N., additional, Marsh, J. E., additional, McConnaughy, K. A., additional, McCoy, S., additional, McIntyre, A. H., additional, Meissner, C. A., additional, Michael, R. B., additional, Mitchell, A. A., additional, Mugayar-Baldocchi, M., additional, Musselman, R., additional, Ng, C., additional, Nichols, A. L., additional, Nunez, N. L., additional, Palmer, M. A., additional, Pappagianopoulos, J. E., additional, Petro, M. S., additional, Poirier, C. R., additional, Portch, E., additional, Rainsford, M., additional, Rancourt, A., additional, Romig, C., additional, Rubínová, E., additional, Sanson, M., additional, Satchell, L., additional, Sauer, J. D., additional, Schweitzer, K., additional, Shaheed, J., additional, Skelton, F., additional, Sullivan, G. A., additional, Susa, K. J., additional, Swanner, J. K., additional, Thompson, W. B., additional, Todaro, R., additional, Ulatowska, J., additional, Valentine, T., additional, Verkoeijen, P. P. J. L., additional, Vranka, M., additional, Wade, K. A., additional, Was, C. A., additional, Weatherford, D., additional, Wiseman, K., additional, Zaksaite, T., additional, Zuj, D. V., additional, and Zwaan, R. A., additional

Published
2014
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31. Protection of metabolic and exercise capacity in unselected weight-losing cancer patients following treatment with recombinant erythropoietin: a randomized prospective study

Author

Daneryd P, Svanberg E, Körner U, Lindholm E, Sandström R, Brevinge H, Pettersson C, Bosaeus I, and Kent Lundholm

Subjects
Male, Cachexia, Anti-Inflammatory Agents, Non-Steroidal, Indomethacin, Anemia, Middle Aged, Recombinant Proteins, Neoplasms, Weight Loss, Exercise Test, Humans, Cyclooxygenase Inhibitors, Female, Prospective Studies, Energy Metabolism, Pulse, Erythropoietin, Aged
Abstract

This study was aimed at evaluating whether anemia could be prevented in unselected weight-losing cancer patients on anti-inflammatory treatment by early and prophylactic treatment with recombinant human erythropoietin (rhEPO) and whether such a benefit could be translated into improved physical function and metabolic efficiency. One hundred eight cancer patients who experienced progressive cachexia due to solid, mainly gastrointestinal tumors were randomized to receive twice daily a cyclo-oxygenase inhibitor (controls; indomethacin, 50 mg twice a day) or indomethacin and erythropoietin, provided on individual basis to prevent development of progressive anemia (study patients; indomethacin, 50 mg twice a day plus rhEPO; range, 12,000-30,000 units per week). All patients were treated and followed up until death or to preterminal stage. Biochemical tests (blood, liver, kidney, and thyroid), nutritional state assessment (food intake and body composition), and exercise testing with simultaneous measurements of respiratory gas exchanges before and during exercise were performed before institution of treatments and then at regular intervals during the treatment period (2-30 months after start). Study and control patients did not differ in survival. rhEPO prevented development of anemia during the entire observation period. This was associated with a significantly more preserved maximum exercise capacity in study patients compared to control patients during the follow-up period (101 +/- 10 versus 66 +/- 6 W; P0.0001), based on more effective ventilation and whole-body respiratory gas exchanges. These improvements were also evident when exercise performance was normalized to lean body mass, an indirect measure of the skeletal muscle mass. The metabolic efficiency, expressed as oxygen uptake per watt produced, was also significantly preserved in rhEPO-treated patients compared to controls (14.1 +/- 1.1 versus 16.3 +/- 0.9 ml O2/W, P0.05). Our results demonstrate that institution of early and prophylactic rhEPO treatment to patients with progressive cancer prevents development of tumor-induced anemia. This achievement was associated with a better preserved exercise capacity, which is explained in part by improved whole-body metabolic and energy efficiency during work load.

Published
1998

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