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131 results on '"Wickramasinghe J"'

1. An Instrument for Precision Controlled Radiation Exposures, Charged Beam Profile Measurement, and Real-time Fluence Monitoring Beyond $10^{16}$ n$_{\textrm{eq}}$/cm$^{2}$

Author

Hoeferkamp, M. R., Wickramasinghe, J. S. T., Grummer, A., Rajen, I., and Seidel, S.

Subjects
Physics - Instrumentation and Detectors, High Energy Physics - Experiment, Physics - Accelerator Physics
Abstract

An instrument has been developed for precision controlled exposures of electronic devices and material samples in particle beams. The instrument provides simultaneously a real time record of the profile of the beam and the fluence received. The system is capable of treating devices with dimensional scales ranging from millimeters to extended objects of cross sections measured in tens of square centimeters. The instrument has been demonstrated to operate effectively in integrated fluences ranging up to a few times $10^{16}$ 1-MeV-neutron-equivalent/cm$^{2}$ (n$_{\textrm{eq}}$). The positioner portion of the system comprises a set of remotely controllable sample holders incorporating cooling and interfaces for sample power and readout, all constructed from low activation technologies. The monitoring component of the system samples the current or voltage of radiation tolerant silicon diodes placed directly in the path of the beam.

Published
2020
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2. Effect of annealing temperature on photovoltaic properties of spin coated CdS films

Author

Dissanayake, D. M. C. U., Wickramasinghe, J. S. T., and Samarasekara, P.

Subjects
Condensed Matter - Materials Science
Abstract

CdS thin film samples were fabricated using spin coating technique on normal glass and conductive glass substrates and annealed at different temperatures. According to the XRD patterns of films prepared on normal glass substrates, polycrystalline films are consist of single phase of CdS. Films synthesized on conductive glass substrates were employed for photovoltaic measurements. Variation of photovoltaic properties with annealing temperature was investigated. The liquid junction photocell was measured in the electrolyte of Na2S2O3/I2. Then, the short circuit photo current and open circuit photo voltage were measured at room temperature under illumination and under dark using a solar cell simulation system. Optical band gap of CdS film samples was determined by measuring UV-visible spectroscopy., Comment: 14 pages, 4 figures, 4 tables

Published
2018

3. Incidence of low-density meteoroids of the Polonnaruwa type

Author

Wickramasinghe, N. C., Wallis, J., Wallis, D. H., Wallis, M. K., Miyake, N., Coulson, S. G., Gibson, Carl H., Wickramasinghe, J. T., Samaranayake, A., Wickramarathne, K., and Hoover, Richard B.

Subjects
Physics - General Physics, Astrophysics - Earth and Planetary Astrophysics
Abstract

The ingress of micrometeorites of cometary origin with densities below ~ 1 g cm-3 into the Earth could average at least 5 tonne per day. Although much of this is burnt upon entry through the atmosphere as meteors, a non-trivial fraction (~10%) which have sizes of ~ 1 m could end up in the form of Polonnaruwa-type meteorites that have mostly gone unnoticed., Comment: 8 pages, 5 figures

Published
2013

5. Impact cratering and the Oort cloud

Author

Wickramasinghe, J. T. and Napier, W. M.

Subjects
Astrophysics
Abstract

We calculate the expected flux profile of comets into the planetary system from the Oort cloud arising from Galactic tides and encounters with molecular clouds. We find that both periodic and sporadic bombardment episodes, with amplitudes an order of magnitude above background, occur on characteristic timescales ~25-35 Myr. Bombardment episodes occurring preferentially during spiral arm crossings may be responsible both for mass extinctions of life and the transfer of viable microorganisms from the bombarded Earth into the disturbing nebulae. Good agreement is found between the theoretical expectations and the age distribution of large, well-dated terrestrial impact craters of the past 250 million years. A weak periodicity of ~36 Myr in the cratering record is consistent with the Sun's recent passage through the Galactic plane, and implies a central plane density ~0.15 M_Sun pc^(-3). This leaves little room for a significant dark matter component in the disc.

Published
2008
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6. Quantum jumps of saturation level rigidity and anomalous oscillations of level number variance in the semiclassical spectrum of a modified Kepler problem

Author

Wickramasinghe, J. M. A. S. P., Goodman, B., and Serota, R. A.

Subjects
Quantum Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Nonlinear Sciences - Exactly Solvable and Integrable Systems
Abstract

We discover quantum Hall like jumps in the saturation spectral rigidity in the semiclassical spectrum of a modified Kepler problem as a function of the interval center. These jumps correspond to integer decreases of the radial winding numbers in classical periodic motion. We also discover and explain single harmonic dominated oscillations of the level number variance with the width of the energy interval. The level number variance becomes effectively zero for the interval widths defined by the frequency of the shortest periodic orbit. This signifies that there are virtually no variations from sample to sample in the number of levels on such intervals., Comment: 18 pages, 3 color figures inline

Published
2007
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7. Mesoscopic fluctuations of off-diagonal matrix elements of the angular momentum and orbital magnetism of free electrons in a rectangular box

Author

Lou, M. X., Wickramasinghe, J. M. A. S. P., and Serota, R. A.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

We study, analytically and numerically, mesoscopic fluctuations of the off-diagonal matrix elements of the orbital angular momentum between the nearest energy levels $i=(n_{x},n_{y}) $ and $f=(k_{x},k_{y}) $ in a rectangular box with incommensurate sides. In the semiclassical regime, where the level number of $i$ is $\cal{N}\gg 1$, our derivation gives $\left< | \hat{L}_{if}| ^{2}\right> \sim \sqrt{\cal{N}}$. Numerical simulations, using simultaneous ensemble averaging (over the aspect ratios of rectangles) and spectral averaging (over the energy interval), are in excellent agreement with this analytical prediction. Physically, the mean is dominated by the level pairs $k_{x}=n_{x}\pm 1$, $k_{y}=n_{y}\mp 1$. Also in a rectangular box, we investigate the mean orbital susceptibility of a free electron gas and argue that it reduces, up to a coefficient, to the two-level van Vleck susceptibility that involves the last occupied (Fermi) level $i$ and the first unoccupied level $f$. This result is confirmed numerically as well, albeit the effect of fluctuations is much more pronounced for the susceptibility since it is due both to large fluctuations in $\left< | \hat{L}_{if}| ^{2}\right>$ and in level separations $\epsilon_{f}-\epsilon_{i}$ (level bunching)., Comment: 24 pages, 20 figures

Published
2005

8. The Absence Of Saturation Of The Level Number Variance In A Rectangular Box

Author

Wickramasinghe, J. M. A. S. P. and Serota, R. A.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

The variance of the number of levels in an energy interval around a level with large quantum numbers (semiclassical quantization) is studied for a particle in a rectangular box. Sampling involves changing the ratio of the rectangle's sides while keeping the area constant. For sufficiently narrow intervals, one finds the usual linear growth with the width of the interval. For wider intervals, the variance undergoes large, non-decaying oscillations around what is expected to be the saturation value. These oscillations can be explained as a superposition of just a few harmonics that correspond to the shortest periodic orbits in the rectangle. The analytical and numerical results are in excellent agreement., Comment: 15 pages, 4 figures

Published
2003

9. Level correlations in integrable systems

Author

Serota, R. A. and Wickramasinghe, J. M. A. S. P.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

We derive a simple analytical expression for the level correlation function of an integrable system. It accounts for both the lack of correlations at smaller energy scales and for global rigidity (level number conservation) at larger scales. We apply our results to a rectangle with incommensurate sides and show that they are in excellent agreement with the limiting cases established in the semiclassical theory of level rigidity., Comment: 5 pages

Published
2001
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10. Radiation tolerance of diamond detectors

Author

Bäni, L, Artuso, M, Bachmair, F, Bartosik, M, Beck, H, Bellini, V, Belyaev, V, Bentele, B, Bergonzo, P, Bes, A, Brom, J-M, Chiodini, G, Chren, D, Cindro, V, Claus, G, Collot, J, Cumalat, J, Curtoni, S, Dabrowski, A, D'Alessandro, R, Dauvergne, D, de Boer, W, Dorfer, C, Dünser, M, Eigen, G, Eremin, V, Forneris, J, Gallin-Martel, L, Gallin-Martel, M-L, Gan, K K, Gastal, M, Ghimouz, A, Goffe, M, Goldstein, J, Golubev, A, Gorišek, A, Grigoriev, E, Grosse-Knetter, J, Grummer, A, Hiti, B, Hits, D, Hoeferkamp, M, Hofmann, T, Hosselet, J, Hügging, F, Hutson, C, Jackman, R, Janssen, J, Jennings-Moors, R, Kagan, H, Kanxheri, K, Kis, M, Kramberger, G, Kuleshov, S, Lacoste, A, Lagomarsino, S, Lo Giudice, A, Paz, I López, Lukosi, E, Maazouzi, C, Mandić, I, Marcatili, S, Marino, A, Mathieu, C, Menichelli, M, Mikuž, M, Morozzi, A, Moscatelli, F, Moss, J, Mountain, R, Oh, A, Olivero, P, Pakpour-Tabrizi, A, Passeri, D, Pernegger, H, Perrino, R, Picollo, F, Pomorski, M, Porter, A, Potenza, R, Quadt, A, Rarbi, F, Re, A, Reichmann, M, Roe, S, Rossetto, O, Becerra, D A Sanz, Schmidt, C, Schnetzer, S, Sciortino, S, Scorzoni, A, Seidel, S, Servoli, L, Smith, D S, Sopko, B, Sopko, V, Spagnolo, S, Spanier, S, Stenson, K, Stone, R, Stugu, B, Sutera, C, Traeger, M, Trischuk, W, Truccato, M, Tuvê, C, Velthuis, J, Wagner, S, Wallny, R, Wang, J C, Welch, J, Wermes, N, Wickramasinghe, J, Yamouni, M, Zalieckas, J, Zavrtanik, M, Departement Physik [ETH Zürich] (D-PHYS), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Syracuse University, CERN [Genève], Georg-August-University = Georg-August-Universität Göttingen, Istituto Nazionale di Fisica Nucleare, Sezione di Catania (INFN), Università degli studi di Catania = University of Catania (Unict), Moscow State Engineering Physics Institute (MEPhI), University of Colorado [Colorado Springs] (UCCS), University College of London [London] (UCL), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Istituto Nazionale di Fisica Nucleare, Sezione di Lecce (INFN, Sezione di Lecce), Istituto Nazionale di Fisica Nucleare (INFN), Czech Technical University in Prague (CTU), Jozef Stefan Institute [Ljubljana] (IJS), Istituto Nazionale di Fisica Nucleare [Ferrara] (INFN), Universität Karlsruhe (TH), Department of Physics [ETH Zürich] (D-PHYS), University of Bergen (UiB), A.F. Ioffe Physical-Technical Institute, Russian Academy of Sciences [Moscow] (RAS), Università degli studi di Torino = University of Turin (UNITO), Ohio State University [Columbus] (OSU), University of Bristol [Bristol], Institute of Theoretical and Experimental Physics [Moscow] (ITEP), National Research Center 'Kurchatov Institute' (NRC KI), The University of New Mexico [Albuquerque], Rheinische Friedrich-Wilhelms-Universität Bonn, Istituto Nazionale di Fisica Nucleare, Sezione di Perugia (INFN, Sezione di Perugia), GSI Helmholtzzentrum für Schwerionenforschung (GSI), Istituto Nazionale di Fisica Nucleare, Sezione di Firenze (INFN, Sezione di Firenze), University of Manchester [Manchester], The University of Tennessee [Knoxville], University of Colorado [Boulder], California State University [Sacramento], Laboratoire Capteurs Diamant (LCD-LIST), Département Métrologie Instrumentation & Information (DM2I), Laboratoire d'Intégration des Systèmes et des Technologies (LIST (CEA)), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire d'Intégration des Systèmes et des Technologies (LIST (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Rutgers University [Camden], Rutgers University System (Rutgers), University of Toronto, RD42 Collaboration, and European Project: 654168,H2020,H2020-INFRAIA-2014-2015,AIDA-2020(2015)

Subjects
instrumentation, History, chemical vapour deposition (CVD), detector, protons, irradiation, neutrons, radiation tolerance, electrode, polycrystalline, Computer Science Applications, Education, radiation, diamond, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Detectors and Experimental Techniques, pions, ionizing radiation, nuclear instrumentation
Abstract

International audience; Diamond is used as detector material in high energy physics experiments due to its inherent radiation tolerance. The RD42 collaboration has measured the radiation tolerance of chemical vapour deposition (CVD) diamond against proton, pion, and neutron irradiation. Results of this study are summarized in this article. The radiation tolerance of diamond detectors can be further enhanced by using a 3D electrode geometry. We present preliminary results of a poly-crystalline CVD (pCVD) diamond detector with a 3D electrode geometry after irradiation and compare to planar devices of roughly the same thickness.

Published
2022
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11. Conservation of copy number profiles during engraftment and passaging of patient-derived cancer xenografts

Author

Woo, X.Y., Giordano, J., Srivastava, A., Zhao, Z.-., Lloyd, M.W., de Bruijn, R., Suh, Y.-., Patidar, R., Chen, L., Scherer, S., Bailey, M.H., Yang, C.-., Cortes-Sanchez, E., Xi, Y., Wang, J., Wickramasinghe, J., Kossenkov, A.V., Rebecca, V.W., Sun, H., Mashl, R.J., Davies, S.R., Jeon, R., Frech, C., Randjelovic, J., Rosains, J., Galimi, F., Bertotti, A., Lafferty, A., O'Farrell, A.C., Modave, E., Lambrechts, D., ter Brugge, P., Marangoni, E., El Botty, R., Kim, H., Kim, J.-., Yang, H.-., Lee, C., Dean, D.A., Davis-Dusenbery, B., Evrard, Y.A., Doroshow, J.H., Welm, A.L., Welm, B.E., Lewis, M.T., Fang, B., Roth, J.A., Meric-Bernstam, F., Herlyn, M., Davies, M.A., Ding, L., Li, S., Govindan, R., Isella, C., Moscow, J.A., Trusolino, L., Byrne, A.T., Jonkers, J., Bult, C.J., Medico, E., Chuang, J.H., Robinson, P.N., Sanderson, B.J., Neuhauser, S.B., Dobrolecki, L.E., Zheng, X., Majidi, M., Zhang, R., Zhang, X., Akcakanat, A., Evans, K.W., Yap, T.A., Li, D., Yucan, E., Lanier, C.D., Saridogan, T., Kirby, B.P., M. J., H., Chen, H., Kopetz, S., Menter, D.G., Zhang, J., Westin, S.N., Kim, M.P., Dai, B., Gibbons, D.L., Tapia, C., Jensen, V.B., Boning, G., Minna, J.D., Park, H., Timmons, B.C., Girard, L., Fingerman, D., Liu, Q., Somasundaram, R., Xiao, M., Yennu-Nanda, V.G., Tetzlaff, M.T., Xu, X., Nathanson, K.L., Cao, S., Chen, F., Dipersio, J.F., Lim, K.H., C. X., M., Rodriguez, F.M., Van Tine, B.A., Wang-Gillam, A., Wendl, M.C., Wu, Y., Wyczalkowski, M.A., Yao, L., Jayasinghe, R., Aft, R.L., Fields, R.C., Luo, J., Fuh, K.C., Chin, V., Digiovanna, J., Grover, J., Koc, S., Seepo, S., Wallace, T., Pan, C.-., Chen, M.S., Carvajal-Carmona, L.G., Kirane, A.R., Cho, M., Gandara, D.R., Riess, J.W., Le, T., deVere White, R.W., Tepper, C.G., Zhang, H., Coggins, N.B., Lott, P., Estrada, A., Toal, T., Arana, A.M., Polanco-Echeverry, G., Rocha, S., A. -H., M., Mitsiades, N., Kaochar, S., O'Malley, B.W., Ellis, M.J., Hilsenbeck, S.G., Ittmann, M., Corso, S., Fiori, A., Giordano, S., van de Ven, M., Peeper, D.S., Miller, I., Bernado, C., Morancho, B., Ramirez, L., Arribas, J., Palmer, H.G., Piris-Gimenez, A., Soucek, L., Dahmani, A., Montaudon, E., Nemati, F., Dangles-Marie, V., Decaudin, D., Roman-Roman, S., Alferez, D.G., Spence, K., Clarke, R.B., Bentires-Alj, M., Chang, D.K., Biankin, A.V., Bruna, A., O'Reilly, M., Caldas, C., Casanovas, O., Gonzalez-Suarez, E., Munoz, P., Villanueva, A., Conte, N., Mason, J., Thorne, R., Meehan, T.F., Parkinson, H., Dudova, Z., Krenek, A., Stuchlik, D., Elemento, O., Inghirami, G., Golebiewska, A., Niclou, S.P., Wisman, G.B.A., de Jong, S., Kralova, P., Sedlacek, R., Claeys, E., Leucci, E., Borsani, M., Lanfrancone, L., Pelicci, P.G., Maelandsmo, G.M., Norum, J.H., Vinolo, E., Serra, V., and Leucci, Eleonora

Subjects
endocrine system diseases, Microarray, gene amplification, Whole Exome Sequencing, Mice, 0302 clinical medicine, Gene expression, Databases, Genetic, Gene duplication, Neoplasm Metastasis, Exome sequencing, Cancer, Regulation of gene expression, 0303 health sciences, Manchester Cancer Research Centre, adult, adult, animal experiment, animal model, animal tissue, breast cancer, microarray, DNA sequencing engraftment, gene amplification, tumor, xenograft, tumor-related gene, Polymorphism, Single Nucleotide/genetics, 3. Good health, Gene Expression Regulation, Neoplastic, 030220 oncology & carcinogenesis, microarray, hormones, hormone substitutes, and hormone antagonists, tumor, endocrine system, DNA sequencing engraftment, animal experiment, DNA Copy Number Variations/genetics, Biology, digestive system, DNA sequencing, Article, animal tissue, 03 medical and health sciences, breast cancer, Breast cancer, Genetics, medicine, Animals, Humans, xenograft, Gene, 030304 developmental biology, Settore MED/04 - Patologia Generale, Microarray analysis techniques, animal model, ResearchInstitutes_Networks_Beacons/mcrc, tumor-related gene, medicine.disease, Xenograft Model Antitumor Assays, Computational biology and bioinformatics, Cancer research, Human cancer
Abstract

Patient-derived xenografts (PDXs) are resected human tumors engrafted into mice for preclinical studies and therapeutic testing. It has been proposed that the mouse host affects tumor evolution during PDX engraftment and propagation, affecting the accuracy of PDX modeling of human cancer. Here, we exhaustively analyze copy number alterations (CNAs) in 1,451 PDX and matched patient tumor (PT) samples from 509 PDX models. CNA inferences based on DNA sequencing and microarray data displayed substantially higher resolution and dynamic range than gene expression-based inferences, and they also showed strong CNA conservation from PTs through late-passage PDXs. CNA recurrence analysis of 130 colorectal and breast PT/PDX-early/PDX-late trios confirmed high-resolution CNA retention. We observed no significant enrichment of cancer-related genes in PDX-specific CNAs across models. Moreover, CNA differences between patient and PDX tumors were comparable to variations in multiregion samples within patients. Our study demonstrates the lack of systematic copy number evolution driven by the PDX mouse host., Analysis of copy number alterations in 1,451 patient-derived xenografts (PDXs) and matched patient tumor samples shows strong conservation from patient tumors through late-passage PDXs and a lack of systematic copy number evolution driven by the mouse host.

Published
2021
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16. A Study of the Radiation Tolerance of CVD Diamond to 70 MeV Protons, Fast Neutrons and 200MeV Pions

Author

Bäni, L., Alexopoulos, A., Artuso, M., Bachmair, F., Bartosik, M. R., Beck, H. C., Bellini, V., Belyaev, V., Bentele, B., Bes, A., Brom, J.-M., Chiodini, G., Chren, D., Cindro, V., Claus, G., Collot, J., Cumalat, J., Curtoni, S., Dabrowski, A. E., D’alessandro, R., Dauvergne, D., De Boer, W., Dorfer, C., Dünser, M., Eigen, G., Eremin, V., Forneris, J., Gallin-Martel, L., Gallin-Martel, M.-L., Gan, K. K., Gastal, M., Ghimouz, A., Goffe, M., Goldstein, J., Golubev, A., Gorišek, A., Grigoriev, E., Grosse-Knetter, J., Grummer, A., Hiti, B., Hits, D., Hoeferkamp, M., Hosselet, J., Hügging, F., Hutson, C., Janssen, J., Kagan, H., Kanxheri, K., Kass, R., Kis, M., Kramberger, G., Kuleshov, S., Lacoste, A., Lagomarsino, S., Lo Giudice, A., Paz, I. L., Lukosi, E., Maazouzi, C., Mandić, I., Marcatili, S., Marino, A., Mathieu, C., Menichelli, M., Mikuž, M., Morozzi, A., Moscatelli, F., Moss, J., Mountain, R., Oh, A., Olivero, P., Passeri, D., Pernegger, H., Perrino, R., Picollo, F., Pomorski, M., Potenza, R., Quadt, A., Rarbi, F., Re, A., Reichmann, M., Roe, S., Rossetto, O., Becerra, D. A. S., Schmidt, C. J., Schnetzer, S., Sciortino, S., Scorzoni, A., Seidel, S., Servoli, L., Smith, D. S., Sopko, B., Sopko, V., Spagnolo, S., Spanier, S., Stenson, K., Stone, R., Stugu, B., Sutera, C., Traeger, M., Trischuk, W., Truccato, M., Tuvè, C., Velthuis, J., Wagner, S., Wallny, R., Wang, J., Wermes, N., Wickramasinghe, J., Yamouni, M., Zalieckas, J., Zavrtanik, M., Hara, K., Ikegami, Y., Jinnouchi, O., Kohriki, T., Mitsui, S., Nagai, R., Terada, S., Unno, Y., Collaboration, RD42, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Intégration des Systèmes et des Technologies (LIST), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, RD42, Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), European Organization for Nuclear Research (CERN), Syracuse University, I. Physikalisches Institut [Göttingen], Georg-August-University = Georg-August-Universität Göttingen, Istituto Nazionale di Fisica Nucleare, Sezione di Catania (INFN), Università degli studi di Catania = University of Catania (Unict), Moscow State Engineering Physics Institute (MEPhI), University of Colorado [Boulder], Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Istituto Nazionale di Fisica Nucleare, Sezione di Lecce (INFN, Sezione di Lecce), Istituto Nazionale di Fisica Nucleare (INFN), Czech Technical University in Prague (CTU), Jozef Stefan Institute [Ljubljana] (IJS), Istituto Nazionale di Fisica Nucleare, Sezione di Firenze (INFN, Sezione di Firenze), Universität Karlsruhe (TH), University of Bergen (UiB), A.F. Ioffe Physical-Technical Institute, Russian Academy of Sciences [Moscow] (RAS), Università degli studi di Torino = University of Turin (UNITO), Ohio State University [Columbus] (OSU), University of Bristol [Bristol], Institute of Theoretical and Experimental Physics [Moscow] (ITEP), National Research Center 'Kurchatov Institute' (NRC KI), The University of New Mexico [Albuquerque], Rheinische Friedrich-Wilhelms-Universität Bonn, Istituto Nazionale di Fisica Nucleare, Sezione di Perugia (INFN, Sezione di Perugia), Helmholtz zentrum für Schwerionenforschung GmbH (GSI), School of Physics and Astronomy [Manchester], University of Manchester [Manchester], The University of Tennessee [Knoxville], California State University [Sacramento], Laboratoire Capteurs Diamant (LCD-LIST), Département Métrologie Instrumentation & Information (DM2I), Laboratoire d'Intégration des Systèmes et des Technologies (LIST (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire d'Intégration des Systèmes et des Technologies (LIST (CEA)), Rutgers, The State University of New Jersey [New Brunswick] (RU), Rutgers University System (Rutgers), University of Toronto, Graduate School of Pure and Applied Sciences, University of Tsukuba, Université de Tsukuba = University of Tsukuba, KEK (High energy accelerator research organization), Tokyo Institute of Technology [Tokyo] (TITECH), This work was partially supported by the Swiss National Science Foundation grant #20FL20_154216, ETH grant 51 15-1, Swiss Government Excellence Scholarship ESKAS No. 2015.0808, UK Science and Technology Facilities Council grant ST/M003965/1 and the U.S. Department of Energy through grant DE-SC0011726., RD42 Collaboration, European Project: 654168,H2020,H2020-INFRAIA-2014-2015,AIDA-2020(2015), Georg-August-University [Göttingen], Università degli studi di Catania [Catania], Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Università degli studi di Torino (UNITO), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire d'Intégration des Systèmes et des Technologies (LIST)

Subjects
Proton, thin film, Hadron, Nuclear Theory, charge collection distance, Chemical vapor deposition, lcsh:Chemical technology, 01 natural sciences, Biochemistry, 030218 nuclear medicine & medical imaging, Analytical Chemistry, Ionizing radiation, 0302 clinical medicine, neutron, sensor, lcsh:TP1-1185, mean drift path, Detectors and Experimental Techniques, polycrystal, Nuclear Experiment, Instrumentation, Charge collection distance, Chemical Vapor Deposition, Mean drift path, Polycrystalline diamond, Radiation damage constant, Radiation tolerance, Schubweg, Single-crystalline diamond, Physics, pion, radiation damage constant, single-crystalline diamond, hadron beam, Atomic and Molecular Physics, and Optics, Neutron temperature, polycrystalline diamond, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], ddc:620, ionizing radiation, damage, proton, Materials science, engineering.material, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Article, Nuclear physics, 03 medical and health sciences, diamond, 0103 physical sciences, ddc:530, Neutron, Irradiation, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Electrical and Electronic Engineering, schubweg, radiation tolerance, 010308 nuclear & particles physics, irradiation fluence, hal-03032394, Diamond, separation of electron–hole pairs, engineering, High Energy Physics::Experiment, Chemical Vapor Deposition (CVD)
Abstract

We measured the radiation tolerance of commercially available diamonds grown by the Chemical Vapor Deposition process by measuring the charge created by a 120 GeV hadron beam in a 50 µm pitch strip detector fabricated on each diamond sample before and after irradiation. We irradiated one group of samples with 70 MeV protons, a second group of samples with fast reactor neutrons (defined as energy greater than 0.1 MeV), and a third group of samples with 200 MeV pions, in steps, to (8.8 ± 0.9) × 1015 protons/cm2, (1.43 ± 0.14) × 1016 neutrons/cm2, and (6.5 ± 1.4) × 1014 pions/cm2, respectively. By observing the charge induced due to the separation of electron–hole pairs created by the passage of the hadron beam through each sample, on an event-by-event basis, as a function of irradiation fluence, we conclude all datasets can be described by a first-order damage equation and independently calculate the damage constant for 70 MeV protons, fast reactor neutrons, and 200 MeV pions. We find the damage constant for diamond irradiated with 70 MeV protons to be 1.62 ± 0.07 (stat) ± 0.16 (syst) × 10−18 cm2 /(p µm), the damage constant for diamond irradiated with fast reactor neutrons to be 2.65 ± 0.13 (stat) ± 0.18 (syst) × 10−18 cm2 /(n µm), and the damage constant for diamond irradiated with 200 MeV pions to be 2.0 ± 0.2 (stat) ± 0.5 (syst) × 10−18 cm2 /(π µm). The damage constants from this measurement were analyzed together with our previously published 24 GeV proton irradiation and 800 MeV proton irradiation damage constant data to derive the first comprehensive set of relative damage constants for Chemical Vapor Deposition diamond. We find 70 MeV protons are 2.60 ± 0.29 times more damaging than 24 GeV protons, fast reactor neutrons are 4.3 ± 0.4 times more damaging than 24 GeV protons, and 200 MeV pions are 3.2 ± 0.8 more damaging than 24 GeV protons. We also observe the measured data can be described by a universal damage curve for all proton, neutron, and pion irradiations we performed of Chemical Vapor Deposition diamond. Finally, we confirm the spatial uniformity of the collected charge increases with fluence for polycrystalline Chemical Vapor Deposition diamond, and this effect can also be described by a universal curve. © 2020 by the authors. Licensee MDPI, Basel, Switzerland., Sensors, 20 (22), ISSN:1424-8220

Published
2020
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21. Reply to editorial and commentaries on Steele, Al-Mufti, Augustyn, Chandrajith, Coghlan, Coulson et al. (2018) 'Cause of Cambrian explosion - Terrestrial or Cosmic?'

Author

Steele, Edward J., Al-Mufti, Shirwan, Augustyn, Kenneth A., Chandrajith, Rohana, Coghlan, John P., Coulson, S. G., Ghosh, Sudipto, Gillman, Mark, Gorczynski, Reginald M., Klyce, Brig, Louis, Godfrey, Mahanama, Kithsiri, Oliver, Keith R., Padron, Julio, Qu, Jiangwen, Schuster, John A., Smith, W. E., Snyder, Duane P., Steele, Julian A., Stewart, Brent J., Temple, Robert, Tokoro, Gensuke, Tout, Christopher A., Unzicker, Alexander, Wainwright, Milton, Wallis, Jamie, Wallis, Daryl H., Wallis, Max K., Wetherall, John, Wickramasinghe, D. T., Wickramasinghe, J. T., Wickramasinghe, N. Chandra, Liu, Yongsheng, Steele, Edward J., Al-Mufti, Shirwan, Augustyn, Kenneth A., Chandrajith, Rohana, Coghlan, John P., Coulson, S. G., Ghosh, Sudipto, Gillman, Mark, Gorczynski, Reginald M., Klyce, Brig, Louis, Godfrey, Mahanama, Kithsiri, Oliver, Keith R., Padron, Julio, Qu, Jiangwen, Schuster, John A., Smith, W. E., Snyder, Duane P., Steele, Julian A., Stewart, Brent J., Temple, Robert, Tokoro, Gensuke, Tout, Christopher A., Unzicker, Alexander, Wainwright, Milton, Wallis, Jamie, Wallis, Daryl H., Wallis, Max K., Wetherall, John, Wickramasinghe, D. T., Wickramasinghe, J. T., Wickramasinghe, N. Chandra, and Liu, Yongsheng

Published
2018

22. Cause of Cambrian Explosion - Terrestrial or Cosmic?

Author

Steele, Edward J., Al-Mufti, Shirwan, Augustyn, Kenneth A., Chandrajith, Rohana, Coghlan, John P., Coulson, S. G., Ghosh, Sudipto, Gillman, Mark, Gorczynski, Reginald M., Klyce, Brig, Louis, Godfrey, Mahanama, Kithsiri, Oliver, Keith R., Padron, Julio, Qu, Jiangwen, Schuster, John A., Smith, W. E., Snyder, Duane P., Steele, Julian A., Stewart, Brent J., Temple, Robert, Tokoro, Gensuke, Tout, Christopher A., Unzicker, Alexander, Wainwright, Milton, Wallis, Jamie, Wallis, Daryl H., Wallis, Max K., Wetherall, John, Wickramasinghe, D. T., Wickramasinghe, J. T., Wickramasinghe, N. Chandra, Liu, Yongsheng, Steele, Edward J., Al-Mufti, Shirwan, Augustyn, Kenneth A., Chandrajith, Rohana, Coghlan, John P., Coulson, S. G., Ghosh, Sudipto, Gillman, Mark, Gorczynski, Reginald M., Klyce, Brig, Louis, Godfrey, Mahanama, Kithsiri, Oliver, Keith R., Padron, Julio, Qu, Jiangwen, Schuster, John A., Smith, W. E., Snyder, Duane P., Steele, Julian A., Stewart, Brent J., Temple, Robert, Tokoro, Gensuke, Tout, Christopher A., Unzicker, Alexander, Wainwright, Milton, Wallis, Jamie, Wallis, Daryl H., Wallis, Max K., Wetherall, John, Wickramasinghe, D. T., Wickramasinghe, J. T., Wickramasinghe, N. Chandra, and Liu, Yongsheng

Abstract

We review the salient evidence consistent with or predicted by the Hoyle-Wickramasinghe (H-W) thesis of Cometary (Cosmic) Biology. Much of this physical and biological evidence is multifactorial. One particular focus are the recent studies which date the emergence of the complex retroviruses of vertebrate lines at or just before the Cambrian Explosion of ∼500 Ma. Such viruses are known to be plausibly associated with major evolutionary genomic processes. We believe this coincidence is not fortuitous but is consistent with a key prediction of H-W theory whereby major extinction-diversification evolutionary boundaries coincide with virus-bearing cometary-bolide bombardment events. A second focus is the remarkable evolution of intelligent complexity (Cephalopods) culminating in the emergence of the Octopus. A third focus concerns the micro-organism fossil evidence contained within meteorites as well as the detection in the upper atmosphere of apparent incoming life-bearing particles from space. In our view the totality of the multifactorial data and critical analyses assembled by Fred Hoyle, Chandra Wickramasinghe and their many colleagues since the 1960s leads to a very plausible conclusion - life may have been seeded here on Earth by life-bearing comets as soon as conditions on Earth allowed it to flourish (about or just before 4.1 Billion years ago); and living organisms such as space-resistant and space-hardy bacteria, viruses, more complex eukaryotic cells, fertilised ova and seeds have been continuously delivered ever since to Earth so being one important driver of further terrestrial evolution which has resulted in considerable genetic diversity and which has led to the emergence of mankind.

Published
2018

37. Liquid water and organics in Comets: implications for exobiology.

Author

Wickramasinghe, J. T., Wickramasinghe, N. C., and Wallis, M. K.

Subjects
*COMETS, *ASTROBIOLOGY, *CLAY minerals, *CARBONACEOUS chondrites (Meteorites), *ASPHALT, *SUBLIMATION (Chemistry), *SOLAR system
Abstract

Liquid water in comets, once considered impossible, now appears to be almost certain. New evidence has come from the discovery of clay minerals in comet Tempel 1, which compliments the indirect evidence in aqueous alteration of carbonaceous chondrites. Infrared spectral indication of clay is confirmed by modelling data in the 8-40 μm and 8-12 μm wavebands on the basis of mixtures of clays and organics. Radiogenic heating producing liquid water cores in freshly formed comets appears more likely on current evidence for solar system formation. A second possibility investigated here is transient melting in comets in the inner solar system, where thin crusts of asphalt-like material, formed due to solar processing and becoming hot in the daytime, can cause melting of sub-surface icy material a few centimetres deep. Supposing comets were seeded with microbes at the time of their formation from pre-solar material, there would be plenty of time for exponential amplification and evolution within the liquid interior and in the transient ponds or lakes formed as the outer layers are stripped away via sublimation. [ABSTRACT FROM AUTHOR]

Published
2009
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38. Level Correlations in Integrable Systems.

Author

Serota, R. A. and Wickramasinghe, J. M. A. S. P.

Subjects
*STATISTICAL correlation, *GEOMETRIC rigidity
Abstract

We derive a simple analytical expression for the level correlation function of an integrable system. It accounts for both the lack of correlations at smaller energy scales and for global rigidity (level number conservation) at larger scales. We apply our results to a rectangle with incommensurate sides and show that they are in excellent agreement with the limiting cases established in the semiclassical theory of level rigidity. [ABSTRACT FROM AUTHOR]

Published
2002
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41. Mars polar cap: a habitat for elementary life.

Author

Wallis, M. K., Wickramasinghe, J. T., and Wickramasinghe, N. C.

Subjects
*CLIMATE change, *SPACE biology, *SALT deposits, *FROZEN ground, *ASTROBIOLOGY
Abstract

Ices in the Martian polar caps are potential habitats for various species of microorganisms. Salts in the ice and biological anti-freeze polymers maintain liquid in cracks in the ices far below 0 °C, possibly down to the mean 220-240 K. Sub-surface microbial life is shielded from ultraviolet (UV) radiation, but could potentially be activated on south-facing slopes under the midday, midsummer Sun. Such life would be limited by low levels of vapour, little transport of nutrients, low light levels below a protective dirt-crust, frost accumulation at night and in shadows, and little if any active translocation of organisms. As in the Antarctic and in permafrost, movement to new habitats depends on geo-climatic changes, which for Mars's north polar cap occur on a 50 000 year scale, except for rare meteorite impacts. [ABSTRACT FROM AUTHOR]

Published
2009
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42. The role of deoxycorticosterone in the biosynthesis of cardenolides in Digitalis lanata

Author

Caspi, E, Wickramasinghe, J. A. F., and Lewis, D. O.

Abstract

The role of deoxycorticosterone in the biosynthesis of digitoxigenin was investigated by the simultaneous administration of deoxy[1,2−3H2]corticosterone and [4−14C]progesterone to a Digitalis lanata plant. The biosynthetically formed [3H,14C]digitoxigenin and deoxy[3H,14C]corticosterone were isolated and the distribution of the two isotopes in these products was determined. The transformation of progesterone into deoxycorticosterone in vivo was established. The biosynthetic route from progesterone via deoxycorticosterone to cardenolides was found to be of little significance.

Published
1968
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43. Biosynthesis of Plant Sterols

Author

Varma, K R, Wickramasinghe, J A F, and Caspi, E

Abstract

It was suggested by previous workers that the C-26 oxygenation step in the biosynthetic conversion of cholesterol to tigogenin ((25R)-5α,22β-spirostan-3β-o1) requires the intermediacy of a C-24 double bond. To examine the validity of this hypothesis, (25-3H)-cholesterol was synthesized, and (4-14C)-(25-3H)-cholesterol (3H:14C ratio, 7.0) was administered to two Digitalis samenplants. A method of isolating the transformation products of tigogenin from the crude saponin mixture, under conditions which did not induce the loss of the C-25 proton, was developed. The (25ξ)-(25-3H)-(4-14C)-5α-cholestan-3β, 16ξ, 22ξ, 26-tetrol was isolated, and its 3H:14C ratio (6.96) was found to be identical with that of the (25-3H)-(4-14C)-cholesterol administered. Jones' oxidation of the tetrol gave (25ξ)-(25-3H)-(4-14C)-3, 16,22-triketo-5α-cholestan-26-oic acid, which on base-catalyzed equilibration lost all the tritium. It was concluded that the C-26 oxygenation of cholesterol during its biosynthetic conversion to tigogenin in D. samen, does not require the intermediacy of a C-24 (or C-25) double bond.

Published
1969
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48. Effects of Elevating Zinc Supplementation on the Health and Production Parameters of High-Producing Dairy Cows.

Author

Oconitrillo M, Wickramasinghe J, Omale S, Beitz D, and Appuhamy R

Abstract

This study's objective was to determine the effects of increasing the dietary added zinc ( Zn ) on the milk production, milk somatic cell count ( SCC ), and immunoglobulin and antioxidant marker concentrations in the blood of dairy cows. Twelve Holstein cows (67 ± 2.5 days in milk) were assigned randomly to (1) a diet containing Zn-methionine at 76 mg/kg of DM ( CTL ) or (2) CTL top-dressed with about 21 mg/kg of DM extra Zn-methionine ( +Zn ) for 70 d. The concentrations of reduced ( GSH ) and oxidized ( GSSG ) glutathione, malondialdehyde ( MDA ), catalase ( CAT ), superoxide dismutase ( SOD ), and immunoglobulins in the blood were measured on d 0, 35, and 70. Compared to CTL, +Zn decreased the dry matter intake ( DMI ) throughout the trial and the milk yield ( MY ) during the first phase of feeding (0-35 d). It, however, increased the milk yield during the last phase (36-70 d). The +Zn tended to have lower and greater milk protein yields than CTL during the first and last feeding phases, respectively. The +Zn tended to decrease the SCC and was associated with lower plasma GSH: GSSG and lower serum SOD concentrations relative to CTL. The +Zn did not affect the immunoglobulins, MDA, or CAT. Despite the early DMI and MY reduction, the prolonged Zn-methionine supplementation at about 100 mg/kg of DM improved the milk yield, possibly as a result of the improved udder health of dairy cows.

Published
2024
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49. Leukemia core transcriptional circuitry is a sparsely interconnected hierarchy stabilized by incoherent feed-forward loops.

Author

Harada T, Kalfon J, Perez MW, Eagle K, Braes FD, Batley R, Heshmati Y, Ferrucio JX, Ewers J, Mehta S, Kossenkov A, Ellegast JM, Bowker A, Wickramasinghe J, Nabet B, Paralkar VR, Dharia NV, Stegmaier K, Orkin SH, and Pimkin M

Abstract

Lineage-defining transcription factors form densely interconnected circuits in chromatin occupancy assays, but the functional significance of these networks remains underexplored. We reconstructed the functional topology of a leukemia cell transcription network from the direct gene-regulatory programs of eight core transcriptional regulators established in pre-steady state assays coupling targeted protein degradation with nascent transcriptomics. The core regulators displayed narrow, largely non-overlapping direct transcriptional programs, forming a sparsely interconnected functional hierarchy stabilized by incoherent feed-forward loops. BET bromodomain and CDK7 inhibitors disrupted the core regulators' direct programs, acting as mixed agonists/antagonists. The network is predictive of dynamic gene expression behaviors in time-resolved assays and clinically relevant pathway activity in patient populations.

Published
2023
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50. A deep learning approach reveals unexplored landscape of viral expression in cancer.

Author

Elbasir A, Ye Y, Schäffer DE, Hao X, Wickramasinghe J, Tsingas K, Lieberman PM, Long Q, Morris Q, Zhang R, Schäffer AA, and Auslander N

Subjects
Humans, Genome, Viral, High-Throughput Nucleotide Sequencing, Deep Learning, Neoplasms genetics, Viruses genetics
Abstract

About 15% of human cancer cases are attributed to viral infections. To date, virus expression in tumor tissues has been mostly studied by aligning tumor RNA sequencing reads to databases of known viruses. To allow identification of divergent viruses and rapid characterization of the tumor virome, we develop viRNAtrap, an alignment-free pipeline to identify viral reads and assemble viral contigs. We utilize viRNAtrap, which is based on a deep learning model trained to discriminate viral RNAseq reads, to explore viral expression in cancers and apply it to 14 cancer types from The Cancer Genome Atlas (TCGA). Using viRNAtrap, we uncover expression of unexpected and divergent viruses that have not previously been implicated in cancer and disclose human endogenous viruses whose expression is associated with poor overall survival. The viRNAtrap pipeline provides a way forward to study viral infections associated with different clinical conditions., (© 2023. The Author(s).)

Published
2023
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