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1,312 results on '"Spitz, L."'

1. Comparison of time-of-flight with MIEZE spectroscopy of H$_2$O: Necessity to go beyond the spin-echo approximation

Author

Beddrich, L., Bender, P., Spitz, L., Wendl, A., Franz, C., Busch, S., Pfleiderer, C., Soltwedel, O., and Jochum, J. K.

Subjects
Condensed Matter - Soft Condensed Matter, Physics - Instrumentation and Detectors
Abstract

Here, we discuss the comparability of data acquisitioned with the Modulation of IntEnsity with Zero Effort data, a neutron spin-echo (NSE) technique to neutron Time-of-Flight (ToF) spectroscopy data. As a NSE technique MIEZE records the intermediate scattering function $\mathcal{I}(Q, \tau)$ making it necessary to perform a Fourier transform to directly compare it to $S(Q, E)$, measured by ToF spectroscopy. Transforming either data set into the complementary parameter space requires detailed knowledge of detector efficiency, instrumental resolution, and background. We discuss these aspects by comparing measurements on pure water performed on the spectrometers RESEDA and TOFTOF under the same experimental conditions. Additionally, we discuss the data evaluation of spin-echo data beyond the SE approximation, which limits these techniques to small energy transfers.

Published
2023

3. Subset selection for intracranial aneurysms for training simulations

Author

Spitz L., Umeh S. C., Behme D., Neyazi B., Sandalcioglu I. E., Preim B., and Saalfeld S.

Subjects
intracranial aneurysms, instance selection, subgroup selection, Medicine
Abstract

We present a framework with two options for selecting a subgroup of training cases for intracranial aneurysm (IA) treatment. Option one, general training, describes training cases that represent a variety of different IAs that represent the diversity of real world cases. This can be achieved via instance selection (IS), which reduces size of a dataset by eliminating redundancies via outlier removal and clustering. Option two, a specific training scenario, describes training that is specialized based on IA features of a specific case, for which we present the novel reverse instance selection (RIS), which introduces similarity to the specific case to the IS methodology. We evaluated our IS and RIS by comparing them to subsets selected based on similarity (SIM) and random sampling (RndS). RIS outperformed SIM and RndS in 79% of experiments. IS outperformed RndS in 33% of experiments. In both scenarios, we observed that our approaches, which balance the weaknesses of SIM and RndS, perform best for small subset sizes close to the database cluster size. Our IS and RIS are flexible in regards to the underlying machine learning and weighting of metrics for evaluation, thus providing a way to select a representative and diverse subset not just for IAs, but also for different kinds of data.

Published
2024
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4. Semi-automatic detection and evaluation of metastases in lymph nodes in diagnostics of the prostate from PET-CT data

Author

Schmidt V., Spitz L., Kreißl M., Saalfeld S., and Genseke P.

Subjects
structured report, lymph node evaluation, prostate tumors, psma pet-ct, morphological analysis, Medicine
Abstract

We present a novel tool designed for the semiautomatic detection and assessment of prostate cancer during recurrence diagnostics using PET-CT with prostate-specific membrane antigen (PSMA). The tool automatically generates a structured report, which is enhanced by 3D images and ensures the reproducibility of the findings. Moreover, the area of the findings is automatically determined and can be corrected manually. Image data from 50 patients following radical prostatectomy was used. Our approach and its user interface were qualitatively evaluated by a nuclear medicine specialist. The segmentation analysis revealed a requirement for further automation. The resulting report was deemed highly beneficial, particularly in terms of the resulting reproducibility and the presentation of 3D images depicting the findings. The presented tool has great potential for much-needed support in everyday clinical practice, as it facilitates the communication of the diagnostic results to colleagues and patients and thus prevents misunderstandings.

Published
2024
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5. Morphologic and hemodynamic analysis of intracranial mirror aneurysms

Author

Spitz L., Schmidt J., Korte J., Berg P., Behme D., Neyazi B., Preim B., and Saalfeld S.

Subjects
intracranial aneurysms, mirror aneurysms, morphological analysis, hemodynamic analysis., Medicine
Abstract

Intracranial mirror aneurysms are pathologic dilatations of cerebral arteries that occur at identical locations in both hemispheres. They do not always have identical sizes, shapes, or rupture states, despite identical patient-specific risk factors. As a subgroup of multiple aneurysms and thus small amounts of data, clinical research about their causes and development has not been conclusive. Using eight patients with 16 mirror aneurysms with different rupture states, we investigated differences between the hemispheres. We virtually performed stitching: detaching the aneurysm domes to place them on the opposite parent vessel to assess the influence of aneurysm morphology and upstream parent vessel shape on hemodynamics. In the unaltered datasets, we found that blood flow within aneurysms in the left hemisphere has higher wall shear stress and velocity. After stitching, we found that both upstream parent vessel as well as aneurysm morphology influence hemodynamics. Morphologic parameters like size, undulation index, and aneurysm angle had a higher influence. In a short rupture risk analysis we found a correlation between rupture and aspect ratio and non-sphericity index. Overall, we found possible indicators for mirror aneurysm analysis that illustrated the importance of morphological analysis, though more datasets are necessary for conclusive statements about special treatment for mirror aneurysms.

Published
2024
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7. Optimized signal deduction procedure for the MIEZE spectroscopy technique

Author

Jochum, J. K., Spitz, L., Franz, C., Wendl, A., Leiner, J. C., Pfleiderer, C., and Soltwedel, O.

Subjects
Condensed Matter - Strongly Correlated Electrons, Physics - Applied Physics, Physics - Instrumentation and Detectors
Abstract

We report a method to determine the phase and amplitude of sinusoidally modulated event rates, binned into four bins per oscillation, based on data generated at the resonant neutron spin-echo spectrometer RESEDA. The presented algorithm relies on a reconstruction of the unknown parameters. It omits a calculation intensive fitting procedure and avoids contrast reduction due to averaging effects. It allows the current data acquisition bottleneck at RESEDA to be relaxed by a factor of four and thus increases the potential time resolution of the detector by the same factor. We explain the approach in detail and compare it to the established fitting procedures of time series having four and 16 time bins per oscillation. In addition we present the empirical estimates of the errors of the three methods and compare them to each other. We show that the reconstruction is unbiased, asymptotic, and efficient for estimating the phase. Reconstructing the contrast increases the error bars by roughly 10% as compared to fitting 16 time binned oscillations. Finally, we give heuristic, analytical equations to estimate the error for phase and contrast as a function of their initial values and counting statistics., Comment: 15 pages, 5 figures, published in Journal of Applied Crystallography

Published
2021
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8. Equivalence of ELSV and Bouchard-Mari\~no conjectures for $r$-spin Hurwitz numbers

Author

Shadrin, S., Spitz, L., and Zvonkine, D.

Subjects
Mathematics - Algebraic Geometry
Abstract

We propose two conjectures on Huwritz numbers with completed $(r+1)$-cycles, or, equivalently, on certain relative Gromov-Witten invariants of the projective line. The conjectures are analogs of the ELSV formula and of the Bouchard-Mari\~no conjecture for ordinary Hurwitz numbers. Our $r$-ELSV formula is an equality between a Hurwitz number and an integral over the space of $r$-spin structures, that is, the space of stable curves with an $r$th root of the canonical bundle. Our $r$-BM conjecture is the statement that $n$-point functions for Hurwitz numbers satisfy the topological recursion associated with the spectral curve $x = -y^r + \log y$ in the sense of Chekhov, Eynard, and Orantin. We show that the $r$-ELSV formula and the $r$-BM conjecture are equivalent to each other and provide some evidence for both., Comment: 32 pages

Published
2013
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9. Integrals of psi-classes over double ramification cycles

Author

Buryak, A., Shadrin, S., Spitz, L., and Zvonkine, D.

Subjects
Mathematics - Algebraic Geometry, 14C17, 14H10
Abstract

DR-cycles are certain cycles on the moduli space of curves. Intuitively, they parametrize curves that allow a map to \mathbb{P}^1 with some specified ramification profile over two points. They are known to be tautological classes, but in general there is no known expression in terms of standard tautological classes. In this paper, we compute the intersection numbers of those DR-cycles with any monomials in psi-classes when this intersection is zero-dimensional., Comment: 43 pages

Published
2012
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10. Identification of the Givental formula with the spectral curve topological recursion procedure

Author

Dunin-Barkowski, P., Orantin, N., Shadrin, S., and Spitz, L.

Subjects
Mathematical Physics, High Energy Physics - Theory, Mathematics - Algebraic Geometry
Abstract

We identify the Givental formula for the ancestor formal Gromov-Witten potential with a version of the topological recursion procedure for a collection of isolated local germs of the spectral curve. As an application we prove a conjecture of Norbury and Scott on the reconstruction of the stationary sector of the Gromov-Witten potential of $\CP1$ via a particular spectral curve., Comment: 36 pages

Published
2012
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11. Givental graphs and inversion symmetry

Author

Dunin-Barkowski, P., Shadrin, S., and Spitz, L.

Subjects
Mathematical Physics, 53D45, 37K10
Abstract

Inversion symmetry is a very non-trivial discrete symmetry of Frobenius manifolds. It was obtained by Dubrovin from one of the elementary Schlesinger transformations of a special ODE associated to a Frobenius manifold. In this paper, we review the Givental group action on Frobenius manifolds in terms of Feynman graphs and obtain an interpretation of the inversion symmetry in terms of the action of the Givental group. We also consider the implication of this interpretation of the inversion symmetry for the Schlesinger transformations and for the Hamiltonians of the associated principle hierarchy., Comment: 26 pages; revised according to the referees' remarks

Published
2012
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12. On double Hurwitz numbers with completed cycles

Author

Shadrin, S., Spitz, L., and Zvonkine, D.

Subjects
Mathematics - Combinatorics, Mathematics - Algebraic Geometry
Abstract

In this paper, we collect a number of facts about double Hurwitz numbers, where the simple branch points are replaced by their more general analogues --- completed (r+1)-cycles. In particular, we give a geometric interpretation of these generalised Hurwitz numbers and derive a cut-and-join operator for completed (r+1)-cycles. We also prove a strong piecewise polynomiality property in the sense of Goulden-Jackson-Vakil. In addition, we propose a conjectural ELSV/GJV-type formula, that is, an expression in terms of some intrinsic combinatorial constants that might be related to the intersection theory of some analogues of the moduli space of curves. The structure of these conjectural "intersection numbers" is discussed in detail., Comment: 31 pages

Published
2011
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13. The spectral curve and the Schrödinger equation of double Hurwitz numbers and higher spin structures

Author

Mulase, M, Shadrin, S, and Spitz, L

Subjects
math.AG, math-ph, math.MP, Pure Mathematics, Mathematical Physics
Abstract

We derive the spectral curves for q-part double Hurwitz numbers, r-spin simple Hurwitz numbers, and arbitrary combinations of these cases, from the analysis of the unstable (0, 1)-geometry. We quantize this family of spectral curves and obtain the Schrödinger equations for the partition function of the corresponding Hurwitz problems. We thus confirm the conjecture for the existence of quantum curves in these generalized Hurwitz number cases.

Published
2013

19. Tracheomalacia

Author

Spitz, L., Phelan, P. D., Beasley, S. W., editor, Myers, N. A., editor, and Auldist, A. W., editor

Published
1991
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20. LEARNING ABOUT SYSTEMS BY DEVELOPING INTERACTIVE DIAGRAMS

Author

Bredeweg, B., Kragten, M., Spitz, L., Gómez Chova, L., López Martínez, A., Candel Torres, I., Theory of Computer Science (IVI, FNWI), and Faculteit Onderwijs en Opvoeding

Abstract

Systems thinking is often not systematically taught in secondary education even though it is known that learners do not develop this kind of thinking on their own. As a result, students have limited skills and are insufficiently equipped for the challenges of modern society. Additionally, educators are searching for didactic approaches and accompanying tools that enable and support learners in actively creating their knowledge and developing their skills.To address these challenges, we are transforming techniques from Artificial Intelligence known as Qualitative Reasoning into an interactive browser application that allows learners to independently construct system diagrams that explain the behaviour of systems, especially emphasising cause-effect reasoning. Our work consists of a 4-year project during which we refine the software and develop and evaluate the required learning material in close collaboration with high school teachers in the Netherlands (grade 9 to 12).We have developed an online workspace for teachers and learners. In addition to the overall software information website (https://www.dynalearn.nl) it consists of three spaces: create, material and administration, each with a unique URL (https://create.dynalearn.nl, etc.). Create refers to the software for creating qualitative representations (runs as an app in common browsers). Although available for use and fully functioning, the app is occasionally updated with new features developed in the project when these features have become sufficient stable. The front end of Create is a JavaScript-based app for creating, running and inspecting qualitative representations. Material refers to the database with educational materials. Models, assignments and supporting documents developed and evaluated in the project are made available for wider use via this database. An Administration system is available that allows teachers to place students in projects (e.g., analogous to existing classes) and allow them to participate in a learning activity. For each project the teacher can specify specific settings regarding the working of the software and as such steer the kind of systems thinking the students will engage with.In this contribution, we report on the ideas behind this project (Denker, https://denker.nu) and on the results obtained during the first year in which we worked with teachers and learners in grade 9.

Published
2021

23. Informed Consent

Author

Baum, Michael, Kestin, I. G., Josse, S. E., Brewster, David H., Bain, Marion R. S., Chalmers, James W. T., Gould, Ann, Dewar, John A., George, W. David, Nottingham, John, Winter, Andrew J., Mullis, David, Radcliffe, Keith W., Wilcox, D. T., Wilcock, F., Spitz, L., and Pierro, A.

Published
1998

29. Hirschsprung's disease: functional and psychological follow up comparing total colonic and rectosigmoid aganglionosis. (Original Article)

Author

Ludman, L., Spitz, L., Tsuji, H., and Pierro, A.

Subjects
Hirschsprung's disease -- Care and treatment, Family and marriage, Health, Care and treatment
Abstract

Aims: To compare the long term functional and psychosocial outcomes following surgical treatment for total colonic aganglionosis (TCA) with those in an age and gender matched group of patients with [...]

Published
2002

36. Sir Peter Freyer Memorial Lecture and Surgical Symposium 15th and 16th September, 1995

Author

Calleary, J., Tansey, C., McCormack, J., Kapur, S., Doyle, J., Flynn, J., Curran, A. J., Smyth, D., Kane, B., Toner, M., Timon, C. V. I., Cronin, K. J., O’Donoghue, J., Darmanin, F. X., McCann, J., Campbell, F., Redmond, H. P., Condron, C., Bouchier-Hayes, D., Aizaz, K., MacGowan, S. W., O’Donnell, A. F., Luke, D. A., McGovern, E., Morrin, M., Khan, F., Delaney, P. V., Lavelle, S. M., Kanagaratnam, B., Cuervas-Mons, V., Gauthier, A., Gips, C., Santos, R. Marques dos, Molino, G. P., Theodossi, A., Tsiftsis, D. D., Boyle, C. J. O., Boyle, T. J., Kerin, M. J., Courtney, D. M., Quill, D. S., Given, H. F., O’Brien, D. F., Kelly, E. J., Kelly, J., Richardson, D., Fanning, N. F., Brennan, R., Horgan, P. G., Keane, F. B. V., Reid, S., Walsh, C., Patock, R., Hall, J., Evoy, D., Magd-Eldin, M., Curran, D., Keeling, P., Ade-Ajayi, N., Spitz, L., Kiely, E., Drake, D., Klein, N., O’Hanlon, D. M., Karat, D., Callanan, K., Crisp, W., Griffin, S. M., Murchan, P. M., Mancey-Jones, B., Sedman, P., Mitchell, C. J., Macfie, J., Scott, D., Raimes, S., O’Boyle, C. J., Maher, D., Willsher, P. C., Robertson, J. F. R., Hilaly, M., Blarney, R. W., Shering, S. G., Mitrovic, S., Rahim, A., McDermott, E. W., O’Higgins, N. J., Murphy, C. A., Morgan, D., Elston, C. W., Ellis, I. O., O’Sullivan, M. P., O’Riordain, M. G., Stack, J. P., Barry, M. K., Ennis, J. T., Fitzpatrick, J. M., Gorey, T. F., Kollis, J., Mullet, H., Smith, D. F., Zbar, A., Murray, M. J., McDermott, E. W. M., Smyth, P. P. A., Kapucouglu, N., Holmes, S., Holland, P., McCollum, P. T., da Silva, A., de Cossart, L., Hamilton, D., Kelly, C. J., Stokes, K., Broe, P., Crinnion, J., Grace, P. A., Morton, N., Ross, N., Naidu, S., Gervaz, P., Holdsworth, R. J., Stonebridge, P. A., O’Donnell, A., Carson, K., Phelan, D., McBrinn, S., McCarthy, D., Javadpour, H., McCarthy, J., Neligan, M., Caldwell, M. T. P., McGrath, J. P., Byrne, P. J., Walsh, T. N., Lawlor, P., Timon, C., Stuart, R. C., Murray, K., Carney, A., Johnston, J. G., Egan, B., O’Connell, P. R., Donoghue, J., Pollock, A., Hyde, D., Hourihan, D., Tanner, W. A., Donohue, J., Fanning, N., Horgan, P., Mahmood, A., Dave, K., Stewart, J., Cole, A., Hartley, R., Brennan, T. G., O’Donoghue, J. M., O’Sullivan, S. T., Beausang, E., Panchal, J., O’Shaughnessy, M., O’Grady, P., Watson, R. W. G., Johnstone, D., O’Donnell, J., McCarthy, E., Flynn, N., O’Dwyer, T., Curran, C., Duggan, S., Tierney, S., Qian, Z., Lipsett, P. A., Pitt, H. A., Lillemoe, K. D., Kollias, J., Morgan, D. A. L., Young, I. S., Regan, M. C., Geraghty, J. G., Suilleabhain, C. B. O., Rodrick, M. L., Horgan, A. F., Mannick, J. A., Lederer, J. A., Hennessy, T. P. J., Canney, M., Feeley, K., Connolly, C. E., Abdih, H., Finnegan, N., Da Costa, M., Shafii, M., Martin, A. J., Mulcahy, D., Dolan, M., Stephens, M., McManus, F., Walsh, M., O’Brien, D. P., Phillips, J. P., Carroll, T. A., O’Brien, D., Rawluk, D., Sullivan, T., Herbert, K., Kerins, M., O’Donnell, M., Lawlor, D., McHugh, M., Edwards, G., Rice, J., McCabe, J. P., Sparkes, J., Hayes, S., Corcoran, M., Bredin, H., O’Keeffe, D., Candon, J., Mulligan, E. D., Lynch, T. H., Mulvin, D., Vingers, L., Smith, J. M., Corby, H., Barry, K., Eardley, I., Frick, J., Goldwasser, B., Wiklund, P., Rogers, E., Weaver, R., Scardino, P. T., Kumar, R., Puri, P., Adeyoju, A. B., Lynch, T., Corr, J., McDermott, T. E. D., Grainger, R., Thornhill, J., Butler, M., Keegan, D., Hegarty, N., McCarthy, P., Mirza, A. H., O’Sullivan, M., Neary, P., O’Connor, T. P. F., McCormack, D., Cunningham, K., Cassidy, N., Sullivan, T., Mulhall, K., Murphy, M., Puri, A., Dhaif, B., Carey, P. D., Delicata, R. J., Abbasakoor, F., Stephens, R. B., Hussey, A. J., Garrihy, B., Nolan, D. J., McAnena, O. J., Fitzgerald, R., Watson, D., Coventry, B. J., Malycha, P., Ward, S. C., Kwok, S. P. Y., Lau, W. Y., Bergman, J. W., Hacking, G. E. B., Metreweli, C., Li, A. K. C., Madhavan, P., Donohoe, J., O’Donohue, M., McNamara, D. A., and O’Donohoe, M. K.

Published
1995
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