Дисертації з теми "Nuclear resonant scattering"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-45 дисертацій для дослідження на тему "Nuclear resonant scattering".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Masuda, Ryo. "Dependence of incoherent nuclear resonant scattering of synchrotron radiation on the number of resonant nuclei." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136766.
Повний текст джерелаKurokuzu, Masayuki. "Studies on Iron Chalcogenide by Mossbauer Spectroscopy and Nuclear Resonant Inelastic Scattering." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188478.
Повний текст джерелаSergueev, Ilia. "Nuclear resonant scattering for the study of dynamics of viscous liquids and glasses." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=970780192.
Повний текст джерелаSaito, Makina. "Development of Time-Domain Interferometry Method Using Nuclear Resonant Scattering and Its Applications." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/157761.
Повний текст джерелаWalshe, Joseph Michael. "Resonant scattering studies of 24Mg and 28Mg and the search for nuclear water." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6514/.
Повний текст джерелаHigashitaniguchi, Satoshi. "Studies on Lanthanum Iron Oxypnictide Superconductors byMossbauer Spectroccopy and Nuclear Resonant Inelastic Scattering." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/124417.
Повний текст джерелаTorresi, Domenico. "Excitation of unbound states in 12B via the 8Li-alpha resonant elastic scattering." Thesis, Universita' degli Studi di Catania, 2011. http://hdl.handle.net/10761/125.
Повний текст джерелаPrivalov, Timofei. "Electronic and nuclear dynamics of X-ray processes." Doctoral thesis, Stockholm : Tekniska högsk, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3189.
Повний текст джерелаCaporaletti, Federico. "Atomic dynamics in glass-forming liquids during the Johari-Goldstein relaxation." Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/263839.
Повний текст джерелаScherthan, Lena [Verfasser]. "Exploring hyperfine interactions and molecular vibrations of Dy and Fe containing single-molecule magnets using synchrotron-based nuclear resonant scattering / Lena Scherthan." Düren : Shaker, 2020. http://d-nb.info/1215461739/34.
Повний текст джерелаIwasaki, Masayuki. "Nonlocal potentials and nuclear resonance scattering /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu148726053195632.
Повний текст джерелаTran, Vivian Y. "Computational treatments for neutron resonance elastic scattering in Monte Carlo nuclear simulations." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/106693.
Повний текст джерелаThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 58-60).
Simulations are vital to the safe design and operation of nuclear reactors. It is therefore important that they accurately treat the physics of nuclear interactions. This work investigates the phenomenon of neutron resonance scattering with a moving target, which can affect the post-collision properties of the neutron and macroscopic values such as temperature reactivity coefficients. First, this research validates a faster computational treatment for resonance scattering--the accelerated resonance elastic scattering (ARES) kernel sampling method--against the already verified Doppler broadening rejection correction (DBRC) treatment in the open-source OpenMC Monte Carlo neutron transport code being developed at the Massachusetts Institute of Technology. In an effort to improve computational efficiency, the optimal energy limits where this phenomenon should be treated are determined and compared to the less costly but inaccurate approximation of assuming a constant constant cross section for determining the reaction kinematics. To reduce memory requirements and facilitate coupling with heat transfer, a new data representation was recently adopted in OpenMC based on the multipole formalism. However, this new approach invalidates the previous implementations of DBRC and ARES. This thesis thus developed a modified DBRC algorithm compatible with the new data representation. This new method is also validated against the previous DBRC method. While more computationally costly, the use of the multipole representation in treating resonance scattering reduces memory requirements by a hundred-fold and facilitates the representation of temperature dependent cross sections.
by Vivian Y. Tran.
S.B.
Pellegri, L. "ON THE NATURE OF THE PYGMY DIPOLE RESONANCE IN 124SN VIA INELASTIC SCATTERING OF 17O." Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/233240.
Повний текст джерелаWeatherhead, Ian. "Investigation of siloxane-silica interactions by nuclear magnetic resonance and small-angle neutron scattering." Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322612.
Повний текст джерелаBlomberg, Adam. "LOW MOMENTUM TRANSFER MEASUREMENTS OF PION ELECTROPRODUCTION AND VIRTUAL COMPTON SCATTERING AT THE DELTA RESONANCE." Diss., Temple University Libraries, 2016. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/406306.
Повний текст джерелаPh.D.
Non-spherical components of the nucleon wave function are measured through p(e,e'p)π experiment at the Δ+(1232) resonance for Q2 = 0.04, 0.09, and 0.13 (GeV/c)2 utilizing the Jefferson National Accelerator Facility (JLab) pulsed beam and Hall A spectrometers. The new data extend the measurements of the Coulomb quadrupole amplitude to the lowest momentum transfer ever reached. The results disagree with predictions of constituent quark models and are in reasonable agreement with dynamical calculations that include pion cloud effects, chiral effective field theory and lattice calculations. The reported measurements indicate that improvement is required to the theoretical calculations and provide valuable input that will allow their refinements. The Coulomb to magnetic multipole ratio (CMR) and generalized polarizability (GP) of the nucleon are also measured through virtual Compton scattering (VCS) for Q² = 0.2 (GeV/c)2 utilizing the Mainz Microtron (MAMI) continuous beam and A1 spectrometers. This data represents the first low Q² GP measurement at the Δ+(1232) resonance. The GP measurement explores a region where previous data and theoretical calculations disagree. The CMR measurement will be the first VCS extraction to compare with world data generated through pion electroproduction. The Dispersion Relation (DR) model used for the VCS extraction provides a new theoretical framework for the data signal and backgrounds that is largely independent from the pion electroproduction models. The independence of the DR from the traditional models provides a strong crosscheck on the ability of the models to isolate the data signal.
Temple University--Theses
Alexeev, Pavel [Verfasser], and Ralf [Akademischer Betreuer] Röhlsberger. "Nuclear Resonance Scattering Study of Iridates, Iridium and Antimony Based Pyrochlores / Pavel Alexeev ; Betreuer: Ralf Röhlsberger." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2017. http://d-nb.info/1130323307/34.
Повний текст джерелаBarnfather, Karl Jon. "A nuclear magnetic resonance and quasielastic neutron scattering study of hydrogen diffusion in metal-hydrogen systems." Thesis, University of Warwick, 1992. http://wrap.warwick.ac.uk/110787/.
Повний текст джерелаSwanson, Donald Raymond. "Properties of ³He films on Nuclepore and a path integral theory of atomic scattering at the surface of liquid ?He /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu148732358362224.
Повний текст джерелаTERREMOTO, LUIS A. A. "Experimento de coincidência sup(26)Mg(e,e'c)." reponame:Repositório Institucional do IPEN, 1993. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11627.
Повний текст джерелаMade available in DSpace on 2014-10-09T14:09:11Z (GMT). No. of bitstreams: 1 12441.pdf: 10808481 bytes, checksum: d5cd417d1d3b2db950bcbe8c2c2da156 (MD5)
Tese (Doutoramento)
IPEN/T
Instituto de Fisica, Universidade de Sao Paulo - IF/USP
Girard-Alcindor, Valerian. "Above barrier narrow resonances in fluorine-15." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMC209.
Повний текст джерелаThe study of unbound nuclei beyond the drip-lines allows us to test our understand- ing of the atomic nucleus under extreme conditions. In this thesis, we have analyzed two separate GANIL experiments in which fluorine 15, located two proton beyond the proton drip-line, was studied. One of the interesting particularity of this nucleus is the presence of particularly narrow negative parity states, above the Coulomb and centrifugal barriers. In this work, we were interested in theses states. We have confirmed the existence of the second excited state 1/2- and have observed two new states, a 5/2- state and a 3/2- state by measuring their decay by emitting either one or two protons. The structure of these states has been discussed and we have tried to explain the origin of the asymmetry observed between the 3/2- state of fluorine 15 and its analogue state in carbon 15. We have also detailed the possibility of gamma transitions between unbound states
Caves, Laurence Wilfred John. "An investigation of high Tc superconductivity in the doped YBa2Cu3O7 and Ln2CuO4 (Ln=La, Nd) systems by neutron scattering and nuclear magnetic resonance." Thesis, University of Warwick, 1992. http://wrap.warwick.ac.uk/110629/.
Повний текст джерелаSilva, Raphaell Júnnio Moreira. "Caracterização estrutural de vidros fluorofosfatos utilizando metodologias de RMN." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-11082014-141413/.
Повний текст джерелаIn this work was studied the development of structure/property correlations for new fluorophosphate glasses compositions: [80Ba(PO3)2 - 20Al(PO3)3]1-x[80BaF2 - 20AlF3]x(0 ≤ x ≤ 40 - mol%). Most suitable techniques for the structural analysis in case of disordered and amorphous material are Nuclear Magnetic Resonance (NMR) Spectroscopy and Raman scattering. Results from X-ray diffraction (XRD) and differential thermal analysis (DTA) reveal that amorphous samples were obtained for all glass compositions up to x ≤ 30. However, the fluorine quantification via 19F MAS NMR suggests significant fluoride loss and/or fluoride/oxide replacement. Both 31P and Raman results indicate gradual conversion of Q2m units to Q1m units with increasing the fluorine concentration. 19F MAS NMR spectra indicate fluorine atoms in two different chemical environments bonded wither covalently to P-atoms or located in a mixed Al/Ba environment. The P-F assignment is confirmed by 19F{31P}-REDOR experiments. 27Al NMR spectra shows dominantly six-coordinated aluminium, and the 27Al{31P}-REDOR data suggest nearly exclusive coordination of Al with phosphate species. The dipolar coupling constant obtained by 31P{31P}-DRENAR are roughly consistent with 31P spectral deconvolution suggesting the presence of Q1and Q2 species.
Nicolini, R. "PYGMY STRUCTURES IN 208PB AND 90ZR STUDIED WITH THE INELASTIC SCATTERING OF 17O AT 20 MEV/U." Doctoral thesis, Università degli Studi di Milano, 2012. http://hdl.handle.net/2434/173172.
Повний текст джерелаShrestha, Manoj. "Partial-wave Analysis of πN Scattering to ηN and KΛ Final States and Extraction of Resonance Parameters from Unitary, Multichannel Fits". Kent State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=kent1353095268.
Повний текст джерелаMétivet, Thibaut. "Lattice QCD at the physical point : pion-pion scattering and structure of the nucleon." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112243/document.
Повний текст джерелаThe formalism of Quantum Chromodynamics on the lattice (or Lattice QCD) allows to perform ab-initio non-perturbative studies of strong-interaction driven processes, as it provides both a covariant regularisation of the theory of QCD and a natural framework for numerical computations. In this work, after a review of the main features of QCD and a step-by-step presentation of our discretization of QCD on a lattice, we undertake detailed studies of two problems of hadronic physics: the phenomenon of resonant scattering and the structure of the nucleon. The lattice calculations are performed with the Budapest-Marseille-Wuppertal Collaboration's 2+1-flavour gauge configurations, which give access to a wide range of lattice spacings, volumes and quarks masses, thereby allowing to study the sensibility of our results on these parameters, and to perform a complete continuum extrapolation. These configurations include dynamical quarks, and use a clover-improved Wilson QCD action. To investigate the scattering of particles on the lattice, we set up a Lüscher analysis for the emblematic case of pion-pion scattering in the channel of the rho meson resonance. We analyse our data with a variational generalized eigenvalue method, and give an in-depth calculation of the scattering phase-shifts and the corresponding resonance parameters, with a full control of the systematic errors. Our results provide an important step for lattice studies of scattering states, as they are the first to be performed at the physical pion mass, where one can see the actual decay of the rho into two pions. The obtained rho meson parameters are in good agreement with the experimental values, and consistent with a weak pion mass dependence of the coupling between the rho and two pions. As for our probe of the structure of the nucleon, we present a complete extraction of the electroweak isovector form factors, with a comprehensive study of the electric charge squared radius and of the axial charge. Our analysis also feature data at the physical pion mass, which turns out to be crucial in order to perform safe extrapolations to the physical point, as the chiral perturbation theory predicts violent variations of these quantities near the massless-quarks point. Our calculation includes source and sink projections onto the nucleon state, as well as a combined fit method between the two-point and three-point correlation functions to control the contamination of our data by excited states. Although one would need more data to perform a high-accuracy determination of the nucleon radius and axial charge at the physical point with a relevant estimation of the systematic errors, the results we obtain are in good agreement with the experiment and suggest that the excited-state effects are under control. Our analysis also highlights that gauge configurations ensembles near the physical pion mass and with large volumes must be used in order to extract accurate information about the nucleon structure from lattice calculations
Guo, Fanqing. "Nuclear reactions with 11C and 14O radioactive ion beams." Berkeley, Calif. : Oak Ridge, Tenn. : Lawrence Berkeley National Laboratory ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2004. http://www.osti.gov/servlets/purl/840236-JlqxbQ/native/.
Повний текст джерелаPublished through the Information Bridge: DOE Scientific and Technical Information. "LBNL--56744" Guo, Fanqing. USDOE Director. Office of Science. Office of Nuclear Physics (US) 12/09/2004. Report is also available in paper and microfiche from NTIS.
Lam, James. "Hydrogen diffusion in concentrated metal hydrides." Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301906.
Повний текст джерелаDienerowitz, Maria. "Plasmonic effects upon optical trapping of metal nanoparticles." Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/1634.
Повний текст джерелаLópez, Asamar Abraham. "Study of the conformational dynamics of prolyl oligopeptidase." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/301430.
Повний текст джерелаLa prolil oligopeptidasa (POP) es un enzim de 81 KDa que hidrolitza pèptids curts amb contingut en prolina. La POP actua en el sistema nerviós central mitjançant interaccions proteïna-proteïna (IPP), i la seva funció biològica està relacionada amb la memòria i els processos cognitius. Per aquesta raó, els inhibidors de la POP són compostos d’interès terapèutic per al tractament dels dèficits cognitius. Recentment, s’ha descobert que els inhibidors de la POP poden prevenir la patogènesis de la malaltia de Pàrkinson, probablement a través d’una interacció directa entre la POP i l’a-sinucleïna (la principal proteïna causant dels processos neurodegeneratius de la malaltia de Parkinson). Tot i que l’estructura cristal·logràfica de la POP està ben definida, no es sap quines són les transicions conformacionals que permeten completar el cicle catalític de la POP. Probablement, aquesta riquesa conformacional també té un paper rellevant en el control de les IPP. Malauradament, l’estudi conformacional complet de la POP és tot un repte degut al seu elevat pes molecular. En aquesta tesis doctoral s’ha emprat una combinació de tècniques biofísiques avançades (en concret, la resonància magnètica nuclear, la dispersió de raigs X de baix angle, i l’espectrometria de masses de mobilitat iònica) conjuntament amb simulacions de dinàmica molecular, per tal d’analitzar la dinàmica conformacional de la POP en solució. A més, s’ha estudiat la possible interacció entre la POP i l’a-sinucleïna mitjançant experiments de RMN. Els resultats obtinguts en aquesta tesi doctoral han demostrat que la POP es troba en solució en un equilibri conformacional lent entre conformacions obertes i tancades, originades a partir de la separació entre dos dominis. Els inhibidors de la POP causen una gran estabilització de la conformació tancada, amb la qual cosa l’equilibri dinàmic es desplaça totalment cap a aquesta conformació. A més, es va poder detectar una interacció dèbil i transitòria entre la POP i l’a-sinucleïna, que esdevenia especialment afavorida en la presència d’inhibidors. Així, els nostres resultats suggereixen que la diversitat conformacional de la POP es necessària per a la seva funció, i que els inhibidors poden desencadenar la seva funció biològica desplaçant l’equilibri conformacional.
Vivona, Sandro. "VAMP7: a model system to study the Longin Domain-SNARE motif." Doctoral thesis, Università degli studi di Padova, 2009. http://hdl.handle.net/11577/3421900.
Повний текст джерелаLe cellule eucariote sono caratterizzate da un complesso sistema di membrane, che offre svariate compartimentazioni con diverse condizioni chimico-fisiche. Se da una parte tale sistema permette la realizzazione di un’ampia gamma di processi biochimici, dall’altra richiede un altrettanto complesso sistema di interscambio atto al suo mantenimento. Tale interscambio è assicurato dal trafficking di vescicole che originano da un compartimento donatore e riversano il loro contenuto in un compartimento accettore attraverso un processo che richiede la fusione delle membrane lipidiche. Tale processo si fonda sull’organizzazione di complessi macromolecolari a cui contribuiscono varie famiglie proteiche ben conservate attraverso l’evoluzione eucariotica. La famiglia delle SNARE è una di queste. Le SNAREs sono considerate i motori della fusione di membrane. La loro capacità di formare complessi specifici in trans tra le due memrane su cui risiedono fornisce il contributo energetico necessario a indurre la fusione degli strati lipidici. Tali complessi consistono in un intreccio di quattro eliche chiamate SNARE motifs, domini di circa 60-70 amino acidi che definiscono tutte le SNAREs. Oltre allo SNARE motif, le SNAREs contengono spesso domini accessori a funzione regolativa. Uno di questi è il Longin Domain (LD). Il LD non è limitato alle sole SNAREs e anzi si ritrova in altre famiglie proteiche tutte coinvolte in processi molecolari riguardanti il ciclo vitale di una vescicola. Nelle SNAREs, il LD definisce una famiglia chiamata Longins, suddivisa a sua volta nelle proteine Ykt6, Sec22b e VAMP7. Il LD consiste di circa 120 aminoacidi organizzati in una struttura spaziale globulare che comprende un piano di cinque foglietti ? (?1- ?5), complessati da un’alfa elica (?1) su un lato e da altre due eliche (?2-?3) sull’altro. In Ykt6 e Sec22b si è dimostrata la possibilità che il LD si ripieghi sullo SNARE motif e lo coordini su una sua superficie idrofobica compresa tra ?1 e ?3. Questo meccanismo si è dimostrato in grado di prevenire la formazione di complessi SNARE non specifici. Tuttavia ben poco si conosce ad oggi sulla natura di questa interazione in termini dinamici, a differenza di quanto invece si sa per un analogo meccanismo osservato nella famiglia SNARE delle Sintaxine. In altri temrini non è dato sapere se nelle Longine questo meccanismo implica una conformazione stabilmente “chiusa” di LD e SNARE, o se piuttosto esso si realizza come un equilibrio dinamico tra conformazioni aperte e chiuse. Una serie di motivi, tra cui l’assenza di dati diretti per questo fenomeno in VAMP7 e la possibilità di usufruire di sue varianti naturali, ci hanno spinto a scegliere VAMP7 come sistema modello per fornire le risposte ai suddetti interrogativi. I nostri dati suggeriscono per le Longine una conformazione stabilmente chiusa, ma non omogenea e capace di cambi conformazionali molto rapidi. Questo lavoro complementa bene quanto già noto per le sintaxine e fornisce dunque la possibilità di comprendere meglio i meccanismi regolativi gneralmente adottati nella fusione vescicolare.
Vandebrouck, Marine. "Première mesure des résonances géantes isoscalaires dans un noyau exotique riche en neutrons : le 68Ni avec la cible active Maya." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00872712.
Повний текст джерелаGupta, Kapil. "Dissection de TFIID, un facteur de transcription général humain : Études structurales etfonctionnelles des sous-ensembles du TFIID human." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAV051/document.
Повний текст джерелаEukaryotic genomes are highly complex and can be very large. For example, the human genome contains approximately 20,000-25,000 protein coding genes. Expression of these genes needs to be tightly regulated at many levels, including chromatin organization, gene transcription, mRNA processing and export and translation, for proper functioning of cellular machinery. Many proteins and protein complexes are involved in these essential regulatory processes, examples include chromatin remodelers, transcriptional activators and coactivators, transcriptional repressors and notably the general transcription machinery. Transcription of protein coding genes in eukaryotes is called Class II gene transcription, and is catalyzed by RNA polymerase II (Pol II). Gene transcription by Pol II requires the cooperative interaction of multiple proteins and protein complexes to facilitate the assembly of a preinitiation complex (PIC) at the core promoter. The PIC comprises Pol II and the General Transcription Factors (GTFs)- TFIIA, TFIIB, TFIID, TFIIE, TFIIF, and TFIIH, together with the Mediator complex and a large variety of transcriptional coactivators.A fundamental step in PIC assembly is recognition of the core promoter by GTF TFIID, a magdalton sized multiprotein complex. In humans, TFIID comprises about twenty subunits made up of 14 different proteins – the TATA box binding protein (TBP) and its associated factors (TAFs, numbered 1 to 13). A range of studies on human TFIID and its subassemblies have been carried out since its discovery more than two decades ago, to understand the structure and mechanism of this essential GTF, but the architecture of TFIID, its activities, its functions, its inner workings and the mechanisms of its cellular assembly have eluded detailed understanding to date.This thesis describes biochemical, biophysical, structural and functional studies carried out on three distinct human TFIID subassemblies. We used a number of structural biology techniques, including crystallization, nuclear magnetic resonance (NMR) spectroscopy and small angle X-ray scattering (SAXS) to analyse a complex formed by the human TBP associated factors TAF1 and TAF7. These structural studies provide detailed insights into the intricate interaction interface formed by TAF1 and TAF7, and, together with other data available from the literature, highlight the dynamic nature of the TAF1/TAF7 interaction in the human TFIID complex.In a second study, we analyzed a novel complex formed by TAF11, TAF13 and TBP using a range of biophysical and biochemical methods including electrophoretic mobility shift assay (EMSA), analytical ultracentrifugation (AUC), size exclusion chromatography (SEC) analysis, pull-down assay, native mass-spectroscopy and chemical cross-linking mass spectroscopy (CLMS). This complex is reminiscent of a so-called TATA-box mimicry discovered previously in a TAF1/TBP complex.As part of the ongoing efforts in the Berger laboratory to determine the structure of human holo-TFIID, we furthermore produced and purified a large (~900 kDa) TFIID subassembly called 9TAF, which is composed of nine different TBP associated factors. We carried out negative stain EM studies and random conical tilt (RCT) analysis on 9TAF to obtain low resolution structural information. These studies set the stage for future cryo-EM studies of this 9TAF complex to obtain a high(er) resolution model to decipher the inner workings of human TFIID
Nguyen, Thi Minh-Ha. "Molecular recognition of ubiquitin and Lysine 63 linked diubiquitin by STAM2 : the effect of the linkers length and flexibility." Thesis, Lyon, 2019. https://n2t.net/ark:/47881/m6668chz.
Повний текст джерелаProtein-protein interaction is considered as an important field of research, as it is the key to control variable cell processes and pathways. In eucaryotic cells, multidomain proteins (MDPs), which consist of more than one domain, take up over 70 % of the pool. Those identical or different domains of a MDP are connected to each other by a linker of variable length and flexibility. For long flexible linker, it allows the protein to sample a wide range of conformation and to adjust interaction in a subtle way. Despite numerous efforts of research on the field, some issues remain unanswered or require further investigation. As part of this thesis, my work aims to define the role taken by the intrinsically disordered linker within MDPs. For that purpose, the STAM2 (Signal transducing adapter molecule 2) protein of the ESCRT (Endosomal Sorting Complexes Required for Transport) machinery was chosen to examine the effect of the flexibility and dynamics of the linker regions on the molecular recognition with ubiquitin and Lysine63-linked di-ubiquitin (K63-Ub2). Such efforts were carried out by designing specific mutants altering the linker regions in different ways. The various truncated versions undergo half or complete deletion of a domain or have their linker either shortened, deleted or modified in the amino acid composition. With a combination of the several biophysical methods namely NMR (Nuclear Magnetic Resonance) spin relaxation, SAXS (Small Angle X-ray Scattering) and CD (Circular Dichroism), the study has demonstrated that the alteration in the linker region modifies the flexibility and the dynamics of the protein, one among them possibly introduces slight change in conformation. Furthermore, the modification of the linker has an impact on the inter-domain motion and alter binding affinities between STAM2 constructs and di-ubiquitin without affecting domains integrity or binding sites. In brief, disordered linkers provide plasticity to the protein, which allow adaptability and specificity to molecular recognition process. As a further application, the linkers included in multidomain proteins could also be the next generation of druggable target as their modification may reduce or completely abolish interactions
Arialdi, Gianluigi. "Contribution de la simulation sur ordinateur à l'interprétation d'expériences spectroscopiques sondant la dynamique locale de fondus de polymères." Doctoral thesis, Universite Libre de Bruxelles, 2003. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211289.
Повний текст джерелаUne contribution à l'étude de la dynamique des polymères non enchevêtrés à l'état fondu est apportée, en se focalisant sur les aspects de dynamique locale d'un polymère particulier déjà fort étudié expérimentalement et par simulation, à savoir le polyéthylène.
Néanmoins, plusieurs nouveaux résultats spécifiques à cette macromolécule linéaire ou ayant une portée sur les fondus de polymères en général sont obtenus grâce à une approche présentant plusieurs aspects originaux.
Notre étude par simulation de la phase liquide du polyéthylène est menée sur une large gamme de températures. La nouveauté principale à ce sujet est l'attention particulière portée à la qualité d'équilibration des échantillons à chaque température. A cette fin, des techniques sophistiquées d'échantillonnage Monte Carlo, mises au point récemment, ont été utilisées pour générer des configurations initiales, la phase de polyéthylène à l'état fondu ainsi obtenue pouvant être stable ou métastable. Un programme original de Dynamique Moléculaire a par ailleurs été écrit, en incorporant diverses procédures d'optimisation adaptées au cas du polyéthylène représenté par un modèle atomistique.
Des observables de diffusion quasi-élastique de neutrons et de résonance magnétique nucléaire sont analysées sur base d'une combinaison linéaire continue d'exponentielles, dont les poids sont donnés par une distribution des temps de relaxation. Cette méthode permet de mieux mettre en évidence les différents processus de relaxation sondés, en évitant les biais induits par un choix particulier de forme analytique servant à une procédure d'ajustement.
Ayant participé à une expérience de spectroscopie par temps de vol de neutrons, un schéma commun d'analyse est adopté pour les données expérimentales et de simulation concernant le polyéthylène à 450 K. D'autre part, une étude très fouillée de l'évolution de la fonction de diffusion intermédiaire incohérente vers les températures plus basses, suivie par simulation, a permis de distinguer différents processus dynamiques et de déterminer parfois leur origine moléculaire.
Ces résultats sont combinés à une analyse de la fonction d'auto corrélation d'orientation d'un vecteur C-H en termes d'une description microscopique des processus dynamiques, proposée lors d'une étude récente de fondus de polyéthylène par résonance magnétique nucléaire du 13C. Deux approches complémentaires sont exploitées afin de révéler les caractéristiques essentielles des deux types de relaxation impliqués.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
Loppinet, Benoit. "Etude de la structure de solutions d'ionomères en solvants polaires par diffusion aux petits angles." Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10208.
Повний текст джерелаBouzar, Khalida. "Approche thermodynamique de l'organisation moléculaire de la phase liquide du toluène sous pression : détermination des expansivités et compressibilités sivities." Paris 6, 1986. http://www.theses.fr/1986PA066312.
Повний текст джерелаTracy, Sally June. "Polaron Hopping in Olivine Phosphates Studied by Nuclear Resonant Scattering." Thesis, 2016. https://thesis.library.caltech.edu/9203/1/SallyJuneTracy_Final2.pdf.
Повний текст джерелаValence fluctuations of Fe2+ and Fe3+ were studied in a solid solution of LixFePO4 by nuclear resonant forward scattering of synchrotron x rays while the sample was heated in a diamond-anvil pressure cell. The spectra acquired at different temperatures and pressures were analyzed for the frequencies of valence changes using the Blume-Tjon model of a system with a fluctuating Hamil- tonian. These frequencies were analyzed to obtain activation energies and an activation volume for polaron hopping. There was a large suppression of hopping frequency with pressure, giving an anomalously large activation volume. This large, positive value is typical of ion diffusion, which indicates correlated motions of polarons, and Li+ ions that alter the dynamics of both.
In a parallel study of NaxFePO4, the interplay between sodium ordering and electron mobility was investigated using a combination of synchrotron x-ray diffraction and nuclear resonant scattering. Conventional Mossbauer spectra were collected while the sample was heated in a resistive furnace. An analysis of the temperature evolution of the spectral shapes was used to identify the onset of fast electron hopping and determine the polaron hopping rate. Synchrotron x-ray diffraction measurements were carried out in the same temperature range. Reitveld analysis of the diffraction patterns was used to determine the temperature of sodium redistribution on the lattice. The diffraction analysis also provides new information about the phase stability of the system. The temperature evolution of the iron site occupancies from the Mossbauer measurements, combined with the synchrotron diffraction results give strong evidence for a relationship between the onset of fast electron dynamics and the redistribution of sodium in the lattice.
Measurements of activation barriers for polaron hopping gave fundamental insights about the correlation between electronic carriers and mobile ions. This work established that polaron-ion interactions can alter the local dynamics of electron and ion transport. These types of coupled processes may be common in many materials used for battery electrodes, and new details concerning the influence of polaron-ion interactions on the charge dynamics are relevant to optimizing their electrochemical performance.
Zhang, Dongzhou. "Applications of Nuclear Resonant Scattering to Further Our Understanding of Earth’s Interior." Thesis, 2015. https://thesis.library.caltech.edu/8747/16/ZhangDongzhou2014Thesis_Oct2016.pdf.
Повний текст джерелаThe elastic and the thermodynamic properties of minerals under extreme P-T conditions are of general importance to the geodynamic modeling and the interpretation of seismic-wave observations. An accurate laboratory determination of these properties provides constraints to determine the composition and temperature of Earth's interior. In this thesis, I focus on the application of nuclear resonant scattering, an advanced synchrotron based spectroscopic technique, to further our understanding of candidate materials in Earth's interior. Specific examples include enstatite, which is an abundant mineral in the mantle, and iron-nickel alloy, which is believed to be the major component of the core. Our nuclear resonant scattering experiments is complemented with other synchrotron based techniques, such as diffraction.
Nuclear resonant scattering is capable of detecting subtle changes in the mineral's hyperfine parameters, and can therefore be sensitive to the transitions occurring in minerals under pressure. For example, we explore the site-specific hyperfine behavior of iron in a 57Fe-enriched powdered enstatite sample using nuclear resonant scattering and diamond-anvil cells in two independent experiments. The (Mg0.980Fe0.020(5) )(Mg0.760Fe0.240)Si2O6 sample is pressurized up to 36 GPa at ambient temperature. In one experiment, NaCl is used as the pressure-transmitting medium, and in the other experiment, Ne surround the sample. Analyses of both data sets reveal a change in the trend or discontinuity in the hyperfine parameters around 10 GPa, indicative of a structural transformation in enstatite. However, the detailed behaviors of the iron sites with pressure appear to depend on the local stress conditions provided by the different pressure media.
Nuclear resonant scattering is also used to measure the elastic properties of iron-bearing enstatite at high pressures. The behavior of synthetic powdered 57Fe-enriched (Mg0.980Fe0.020(5) )(Mg0.760Fe0.240)Si2O6 is explored by X-ray diffraction (XRD) and nuclear resonance inelastic X-ray scattering (NRIXS). The Pbca-structured enstatite sample is compressed in fine pressure increments for our XRD measurements. One structural transition between 10.1 and 12.2 GPa is identified from the XRD data. The XRD reflections observed for the high-pressure phase are best matched with space group P21/c. The partial phonon density of states (DOS) is derived from the raw NRIXS data up to 17 GPa, and from the low-energy region of the DOS, the Debye sound velocity is determined. We use the equation of state determined from XRD and Debye sound velocity to compute the isotropic compressional and shear wave velocities of enstatite at different pressures. We combine density-functional theory with nuclear resonant scattering to understand the local site symmetry of the Fe atoms in our sample. We compare our experimental results with seismic observations to understand large lateral variations in shear wave velocities in the upper mantle.
Recently, nuclear resonant scattering has been shown to be a powerful probe in determining the solid-liquid boundary of iron-bearing materials. To capture the sample's transient temperature fluctuations and reduce uncertainties in melting temperatures, we have developed a Fast Temperature Readout (FasTeR) spectrometer in-line with nuclear resonant scattering measurements under extreme conditions at Sector 3-ID-B of the Advanced Photon Source at Argonne National Laboratory. Dedicated to determining the sample's temperature near its melting point, FasTeR features a fast readout rate (about 100 Hz), high sensitivity, large dynamic range and well-constrained focus. FasTeR is capable of reading out temperatures about 1 to 2 magnitudes faster than the conventional CCD spectrometer, without sacrificing accuracy, and is especially suitable for dynamic measurements at extreme conditions.
By combining nuclear resonant scattering with the laser heated diamond anvil cell and the FasTeR spectrometer, we have determined the melting temperatures of fcc-structured iron and iron-nickel alloy at high pressures. We find that the melting curve of Fe is slightly higher than the melting curve of Fe0.9Ni0.1, but the difference is smaller than the uncertainty. We calculate the fcc-hcp-l triple point of Fe0.9Ni0.1 to be 117±3 GPa and 3285±200 K, and 111±3 GPa and 3390±200 K for Fe. With the fcc-hcp-l triple points of Fe and Fe0.9Ni0.1, and the thermophysical parameters of hcp-Fe determined from a NRIXS measurement, we compute the high pressure melting curves of hcp-structured Fe and Fe0.9Ni0.1. We estimate the upper bound of Earth's inner core-outer core boundary temperature as ~5600±200 K, and we compute the upper bound of outer core temperature with an adiabatic model. We discuss the implications of these temperatures on the phase relations of deep Earth materials.
Sergueev, Ilia [Verfasser]. "Nuclear resonant scattering for the study of dynamics of viscous liquids and glasses / Ilia Sergueev." 2004. http://d-nb.info/970780192/34.
Повний текст джерелаLübbers, Rainer [Verfasser]. "Magnetism and lattice dynamics under high pressure studied by nuclear resonant scattering of synchrotron radiation / von Rainer Lübbers." 2000. http://d-nb.info/961623144/34.
Повний текст джерела"Coherent photon scattering on nuclei in the Δ(1232) resonance region." Thesis, 1993. http://hdl.handle.net/10388/etd-07262012-100113.
Повний текст джерелаHenshaw, Seth. "An Investigation of the Isovector Giant Quadrupole Resonance in 209Bi using Polarized Compton Scattering." Diss., 2010. http://hdl.handle.net/10161/3076.
Повний текст джерела
Giant multipole resonances are a fundamental property of nuclei and
arise from the collective motion of the nucleons inside
the nucleus. Careful studies of these resonances and their properties provides
insight into the nature of nuclear matter and constraints
which can be used to test our theories.
An investigation of the Isovector Giant Quadrupole Resonance (IVGQR)
in 209Bi has been preformed using the High Intensity γ-ray
Source (HIγS) facility. Intense nearly monochromatic
polarized γ-rays were incident upon a 209Bi target producing
nuclear Compton scattered γ-rays that were detected using the HIγS
NaI(Tl) Detector Array (HINDA). The HINDA array consists of six
large (10''x10'') NaI(Tl) core crystals, each surrounded by an
optically segmented 3'' thick NaI(Tl) annulus. The scattered γ-rays
both parallel and perpendicular to the plane of polarization were
detected at scattering angles of 55° and 125° with
respect to the beam axis. This was motivated by the realization that
the term representing the interference between the electric dipole
(E1) and electric quadrupole (E2) amplitudes, which appears in the
theoretical expression for the ratio of the polarized cross sections,
has a sign difference between the forward and backward angles and also
changes sign as the incident γ-ray energy is scanned over the E2
resonance energy. The ratio of cross sections perpendicular and
parallel to the plane of polarization of the incident γ-ray were
measured for thirteen different incident γ-ray energies between 15 and
26 MeV at these two angles and used to extract the parameters of the
IVGQR in 209Bi.
The polarization ratio was calculated at 55° and
125° using a model consisting of E1 and E2 giant resonances as
well as a modified Thomson scattering amplitude. The parameters of the E1 giant
resonance came from previous measurements of the Giant Dipole
Resonance (GDR)
in 209Bi. The finite size of the nucleus was
accounted for by introducing a charge form factor in the (modified)
Thomson amplitude. This form factor was obtained from
measurements of the charge density in inelastic electron scattering
experiments.
The resulting curves were fit to the data by varying the
E2 parameters until a minimum value of the χ2 was found.
The resulting parameters from the fit yield an IVGQR in 209Bi
located at Eres=23.0±0.13(stat)±0.25(sys) MeV
with a width of Γ=3.9±0.7(stat)±1.3(sys) MeV and a
strength of 0.56±0.04(stat)±0.10(sys) Isovector Giant
Quadrupole Energy Weighted Sum Rules (IVQEWSRs).
The ability to make precise measurements of the parameters of the
IVGQR demonstrated by this work opens up new challenges to both
experimental and theoretical work in nuclear structure. A detailed
search for the missing sum rule strength in the case of 209Bi should
be performed. In addition, a systematic study of a number of nuclei
should be studied with this technique in order to carefully examine
the A dependence of the energy, width and sum rule strength of the
IVGQR as a function of the mass number A. The unique properties of
the HIγS facility makes it the ideal laboratory at which to perform
these studies.
Such a data base will provide more stringent tests of nuclear
theory. The effective parameters of collective models can be fine
tuned to account for such precision data. This should lead to new
insights into the underlying interactions responsible for the nature
of the IVGQR. Furthermore, with the recent advances in computational
power and techniques, microscopic shell model based calculations
should be possible and could lead to new insights into the underlying
properties of nuclear matter which are responsible for the collective
behavior evidenced by the existence and properties of the IVGQR.
Dissertation
Geser, Federico Alejandro. "Caracterización dosimétrica y monitoreo in situ para hadronterapia." Doctoral thesis, 2019. http://hdl.handle.net/11086/14465.
Повний текст джерелаActualmente, se cuenta con modernas técnicas para el tratamiento del cáncer incluidas dentro del marco de la radioterapia, conocidas como radioterapias no-convencionales. Estas técnicas fueron investigadas bajo el mismo precepto que todas las terapias de cáncer que utilizan radiaciones ionizantes: realizar la conformación de la dosis en el interior del paciente de la forma más precisa posible, sin dañar tejidos sanos o radio-sensibles. Entre estas técnicas no-convencionales, se encuentra la hadronterapia, que consiste básicamente en la utilización de partı́culas cargadas pesadas (protones, partı́culas alfa, iones de carbono, etc) para la conformación de dosis en pequeños volumenes. Las principales ventajas de la hadronterapia, se deben a la naturaleza del depósito de energı́a descripto por la fı́sica del problema. Dada la alta transferencia lineal de energı́a que poseen los iones utilizados en hadronterapia, los daños biológicos resultan superiores a los de la radioterapia convencional, y por ende es necesario contar con herramientas que permitan establecer el “control / verificación del rango de los iones” en el interior del paciente durante el procedimiento de irradiación. Para este fin, es necesario identificar procesos fı́sicos que produzcan alguna señal interpretable desde el exterior del paciente que sea potencialmente útil para monitorear el haz terapéutico. Una posibilidad consiste en aprovechar las propiedades del agua lı́quida equivalente a las del tejido blando, y analizar los procesos nucleares que den lugar a estados excitados del núcleo de oxı́geno con consecuente emisión foto-nuclear. En este trabajo de tesis, se investigó un nuevo enfoque basado en la posibilidad de monitorear el haz de terapia por medio de algún elemento no presente, en forma natural, en el tejido biológico; que al interactuar de alguna forma con la radiación incidente produzca alguna consecuencia correlacionada con los procesos de interés. Asimismo, se analiza la potencial detección de fotones de aniquilación en la radioterapia convencional debido a la inclusión de nanopartı́culas de oro en el material tejido-equivalente a modo de aproximación experimental a la detección, y correlación con el proceso de irradiación. En términos de hadronterapia, y particularmente la protonterapia, se estudia la factibilidad de aprovechar la fusión nuclear entre protones de energı́as bajas (respecto de las energı́as incidentes de terapia) y el isótopo de boro 11, dando lugar a dos significativas ventajas: la mejora dosimétrica debido a la emisión de partı́culas alfa resultantes del proceso de fusión; y la verificación online e in-situ del rango de los protones, con la consecuente herramienta de diagnóstico por imágenes médicas, debido a la emisión de fotones gamma prompt (“rápidos”).
Nowadays, different techniques are being used for the treatment of cancer in the framework of radiotherapy, thoroughly known as non-conventional radiotherapies. These techniques were researched with the same goal than most cancer therapies utilizing ionizing radiation: conforming the dose inside the patient in the more accurate way possible, sparing healthy or radiosensitive tissues. Among these non-conventional techniques is the hadrontherapy, consisting mainly in using heavy charged particles (protons, alpha particles, carbon ions, etc) to perform the dose conformation in small volumes. The principal advantages of hadrontherapy are due to the nature of the energy deposition mechanism of the charged particles in matter, as described by the physics of the problem. Given the high linear energy transfer (LET) the ions used in hadrontherapy possess, the biological damage is higher than the conventional radiotherapy, and for this reason it is necessary to provide tools that allows the medical physicists to establish the “control / verification of the range of the ions” inside the patient during the irradiation procedure. To this aim, it is necessary to identify physical processes that leads to an interpretable signal outside the patient that are potentially useful for the therapeutic beam monitoring. A posibility consists of taking advantage of the water-equivalent properties of the biological tissue, and analyze the nuclear processes with excited states of the oxygen nuclei with the consecuent emission of a photo-nuclear photon. In this thesis work, a new approach is studied, based on the possibility of monitoring the therapeutic beam using an element not naturally present in the biological tissue, and whose interaction with the ionizing radiation used in the therapy produces a consequence correlated with the process of interest. These are called the “theranostics” methods. Likewise, the potential detection of annihilation photons in conventional radiotherapy is analyzed, using gold nanoparticles inside a tissue-equivalent material, mostly as an experimental approach to the detection and correlation with the irradiation process. In terms of hadrontherapy, particularly regarding protontherapy, this work shows the feasibility of taking advantage of the so-called proton-boron fusion, consisting of using the low-energy protons (respect therapy incident energies) interaction with boron 11 isotopes, which leads to two significant advantages: dosimetric improvement due to the alpha particles produced in the reaction; and an online and in-situ verification of the range of the protons, with the consequent tool for medical imaging, due to the emission of prompt-gamma photons.
Fil: Geser, Federico Alejandro. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.
Usman, Iyabo Tinuola. "Fragmentation of the isoscalar giant quadrupole resonance in low mass 12 -< A -> 40 nuclei and 2+ level density in 40Ca from high energy-resolution (p,p') scattering at 200 MeV." Thesis, 2010. http://hdl.handle.net/10539/7686.
Повний текст джерелаMatiwane, Aphiwe. "Neutron tunneling in nanostructured systems: isotopical effect." Diss., 2018. http://hdl.handle.net/10500/25095.
Повний текст джерелаPhysics
M. Sc. (Physics)