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Zeitschriftenartikel zum Thema „Proton centre“

Autor: Grafiati

Veröffentlicht am 28. Juni 2021

Zuletzt aktualisiert am 11. Februar 2022

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1

McKenna, Paul, Filip Lindau, Olle Lundh, David Neely, Anders Persson und Claes-Göran Wahlström. „High-intensity laser-driven proton acceleration: influence of pulse contrast“. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 364, Nr. 1840 (25.01.2006): 711–23. http://dx.doi.org/10.1098/rsta.2005.1733.

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Proton acceleration from the interaction of ultra-short laser pulses with thin foil targets at intensities greater than 10 18 W cm −2 is discussed. An overview of the physical processes giving rise to the generation of protons with multi-MeV energies, in well defined beams with excellent spatial quality, is presented. Specifically, the discussion centres on the influence of laser pulse contrast on the spatial and energy distributions of accelerated proton beams. Results from an ongoing experimental investigation of proton acceleration using the 10 Hz multi-terawatt Ti : sapphire laser (35 fs, 35 TW) at the Lund Laser Centre are discussed. It is demonstrated that a window of amplified spontaneous emission (ASE) conditions exist, for which the direction of proton emission is sensitive to the ASE-pedestal preceding the peak of the laser pulse, and that by significantly improving the temporal contrast, using plasma mirrors, efficient proton acceleration is observed from target foils with thickness less than 50 nm.

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2

Heinz, Günther. „First steps to proton therapy centre“. Lancet Oncology 1, Nr. 4 (Dezember 2000): 202. http://dx.doi.org/10.1016/s1470-2045(00)00144-3.

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3

Junge, Wolfgang, Michael Haumann, Ralf Ahlbrink, Armen Mulkidjanian und Jürgen Clausen. „Electrostatics and proton transfer in photosynthetic water oxidation“. Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 357, Nr. 1426 (29.10.2002): 1407–18. http://dx.doi.org/10.1098/rstb.2002.1137.

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Photosystem II (PSII) oxidizes two water molecules to yield dioxygen plus four protons. Dioxygen is released during the last out of four sequential oxidation steps of the catalytic centre (S 0 ⇒ S 1 , S 1 ⇒ S 2 , S 2 ⇒ S 3 , S 3 ⇒ S 4 → S 0 ). The release of the chemically produced protons is blurred by transient, highly variable and electrostatically triggered proton transfer at the periphery (Bohr effect). The extent of the latter transiently amounts to more than one H + /e – under certain conditions and this is understood in terms of electrostatics. By kinetic analyses of electron–proton transfer and electrochromism, we discriminated between Bohr–effect and chemically produced protons and arrived at a distribution of the latter over the oxidation steps of 1 : 0 : 1 : 2. During the oxidation of tyr–161 on subunit D1 (Y Z ), its phenolic proton is not normally released into the bulk. Instead, it is shared with and confined in a hydrogen–bonded cluster. This notion is difficult to reconcile with proposed mechanisms where Y Z acts as a hydrogen acceptor for bound water. Only in manganese (Mn) depleted PSII is the proton released into the bulk and this changes the rate of electron transfer between Y Z and the primary donor of PSII P + 680 from electron to proton controlled. D1–His190, the proposed centre of the hydrogen–bonded cluster around Y Z , is probably further remote from Y Z than previously thought, because substitution of D1–Glu189, its direct neighbour, by Gln, Arg or Lys is without effect on the electron transfer from Y Z to P + 680 (in nanoseconds) and from the Mn cluster to Y ox Z .

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4

Aitkenhead, A. H., C. G. Rowbottom und R. I. MacKay. „Throughput Modelling for a Proton Therapy Centre“. Clinical Oncology 23, Nr. 3 (April 2011): S13. http://dx.doi.org/10.1016/j.clon.2011.01.341.

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5

De Saint-Hubert, M., C. Saldarriaga Vargas, O. Van Hoey, W. Schoonjans, V. De Smet, G. Mathot, F. Stichelbaut et al. „SECONDARY NEUTRON DOSES IN A PROTON THERAPY CENTRE“. Radiation Protection Dosimetry 170, Nr. 1-4 (04.11.2015): 336–41. http://dx.doi.org/10.1093/rpd/ncv458.

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6

Hazdra, Pavel, Stanislav Popelka und Adolf Schöner. „Local Lifetime Control in 4H-SiC by Proton Irradiation“. Materials Science Forum 924 (Juni 2018): 436–39. http://dx.doi.org/10.4028/www.scientific.net/msf.924.436.

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The effect of local lifetime control by proton irradiation on the OCVD response of a 10 kV SiC PiN diode was investigated. Carrier lifetime was reduced locally by irradiation with 800 keV protons at fluences up to 1x1011cm-2. Radiation defects were characterized by DLTS and C-V profiling; excess carrier dynamics were measured by the OCVD and analyzed using the calibrated device simulator ATLAS from Silvaco, Inc. Results show that proton implantation followed by low temperature annealing can be used for controllable local lifetime reduction in SiC devices. The dominant recombination centre is the Z1/2defect, whose distribution can be set by irradiation energy and fluence. The local lifetime reduction, which improves diode recovery, can be monitored by OCVD response and simulated using the SRH model accounting for the Z1/2defect.

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Patel, S., J. A. Whitlock, I. A. Olivotto, M. Parliament, N. Laperriere, E. Bouffet und D. D. Eisenstat. „PS1 - 186 Needs Assessment for a Pediatric Proton Therapy Program in Canada“. Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques 43, S4 (Oktober 2016): S12. http://dx.doi.org/10.1017/cjn.2016.362.

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Proton therapy enables normal tissue sparing for curative-intent treatment of children with cancer who require radiation therapy. In the USA and elsewhere, proton therapy is being rapidly adopted, and many new proton centres are being established. Without a proton centre in Canada, children and their families must travel abroad for treatment at high cost and has raised the question whether a Canadian proton therapy facility is needed. METHODS: Canadian Pediatric Oncology centres were surveyed to assess current and future clinical practices. Needs were modeled by screening the Alberta Cancer Registry, ascertaining the number of children eligible for proton RT and comparing to the number who actually received this therapy. RESULTS: Most centres (63%) referred children, and 49 children were referred abroad between 2008 and 2013. Referrals were estimated to increase to 36 cases per annum across Canada. Most respondents (75%) supported that proton therapy will reduce late effects in most or selected cases compared to photon therapy. The registry search revealed 37,170 patients irradiated of which 379 children (1.0%) were potentially eligible for proton therapy, accounting for 15.9% of the new cases of childhood cancers diagnosed in Alberta over the interval. CONCLUSIONS: A strong perceived need for a pediatric proton therapy in Canada was identified. Proton therapy utilization was lower than modeled needs. Future referrals are anticipated to increase, with annual estimated cost of approximately $60 million spent outside of Canada that could be invested within the Canadian health care economy. These issues are worthy of further national discussion.

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Tommasino, Francesco, Marta Rovituso, Eleonora Bortoli, Chiara La Tessa, Giada Petringa, Stefano Lorentini, Enrico Verroi et al. „A new facility for proton radiobiology at the Trento proton therapy centre: Design and implementation“. Physica Medica 58 (Februar 2019): 99–106. http://dx.doi.org/10.1016/j.ejmp.2019.02.001.

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9

Hunter, Naomi, Reid Tingley, Brad Peori und Keith Vaughan. „Triazene derivatives of (1,x)-diazacycloalkanes. Part VIII. Synthesis and characterization of a series of 1,4-di[2-aryl-1-diazenyl]-2-methylpiperazines1“. Canadian Journal of Chemistry 85, Nr. 3 (01.03.2007): 189–96. http://dx.doi.org/10.1139/v07-013.

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A series of 1,4-di-[2-aryl-1-diazenyl]-2-methylpiperazines (4a–n) have been synthesized by the reaction of 2-methylpiperazine with 2 equiv. of the appropriate diazonium salt. The products have been characterized by IR and NMR spectroscopy, and the molecular composition has been verified by HR-EIMS, with accurate mass measurement of the molecular ion. The presence of a chiral centre at C2 of the piperazine ring in the bistriazene 4 creates a multitude of diastereotopic protons in the methylene groups of the piperazine ring, as evidenced by the complexity of the NMR spectra, which nevertheless can be fully assigned in some cases, such as the tolyl- (4h) and phenyl- (4j) derivatives. These two compounds also show a discrimination between the two N-arydiazenyl groups, as evidenced by the doubling of several aromatic-carbon signals in the 13C NMR spectra. The assignment of the proton and carbon signals in 4h and 4j has been aided by the use of 2D NMR spectroscopy. A DEPT spectrum of 4j clearly discriminates the methylene carbons and also indicates the methine carbons of the piperazine ring. COSY spectra provide clear information about the interactions between diastereotopic protons; when these results are combined with the results of HSQC spectroscopy, the proton and carbon signals can be fully correlated, leading to an unequivocal assignment of the proton and carbon atoms of the piperazine ring. The HSQC spectrum of 4j also gives a complete correlation of the aromatic-proton and -carbon signals. These results compare favorably with the previously reported assignments of proton and carbon signals for triazenes of type 1 and bistriazenes of type 3.Key words: triazene, bistriazene, piperazine, 2-methylpiperazine, diastereotopic protons, diazonium coupling, 2D NMR, COSY, DEPT, HSQC.

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Barker, Claire, Matthew Lowe und Ganesh Radhakrishna. „An introduction to proton beam therapy“. British Journal of Hospital Medicine 80, Nr. 10 (02.10.2019): 574–78. http://dx.doi.org/10.12968/hmed.2019.80.10.574.

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Radiotherapy is a highly effective anti-cancer treatment commonly used alongside systemic therapies and surgery to achieve long-term cancer-free survival. Conventional radiotherapy uses photon beams to deliver a high dose of radiation to the tumour volume to eradicate cancer cells. This has to be offset against the irradiation of surrounding normal tissues, as increasing this dose causes more treatment-related toxicity. In August 2018, the NHS's first high energy proton beam therapy centre opened at The Christie NHS Foundation Trust in Manchester. A second NHS centre is scheduled to open in 2020 at the University College London Hospitals NHS Trust. Proton beam therapy may offer dosimetric advantages compared to conventional radiotherapy as a result of its characteristic dose deposition – proton beams deliver a comparatively higher proportion of their dose to the target volume relative to normal tissues, without significant exit doses when compared to conventional photon therapy. Therefore proton beam therapy may be indicated for certain tumours situated next to critical organs or in the paediatric population where quality of life and the reduction of secondary effects from radiation are particularly significant. The indications for proton beam therapy and patient outcomes after treatment will be carefully monitored and evaluated in order to provide a robust evidence base for its use.

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11

Afanasiev, A., R. Vainio, A. P. Rouillard, M. Battarbee, A. Aran und P. Zucca. „Modelling of proton acceleration in application to a ground level enhancement“. Astronomy & Astrophysics 614 (Juni 2018): A4. http://dx.doi.org/10.1051/0004-6361/201731343.

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Context. The source of high-energy protons (above ~500 MeV) responsible for ground level enhancements (GLEs) remains an open question in solar physics. One of the candidates is a shock wave driven by a coronal mass ejection, which is thought to accelerate particles via diffusive-shock acceleration. Aims. We perform physics-based simulations of proton acceleration using information on the shock and ambient plasma parameters derived from the observation of a real GLE event. We analyse the simulation results to find out which of the parameters are significant in controlling the acceleration efficiency and to get a better understanding of the conditions under which the shock can produce relativistic protons. Methods. We use the results of the recently developed technique to determine the shock and ambient plasma parameters, applied to the 17 May 2012 GLE event, and carry out proton acceleration simulations with the Coronal Shock Acceleration (CSA) model. Results. We performed proton acceleration simulations for nine individual magnetic field lines characterised by various plasma conditions. Analysis of the simulation results shows that the acceleration efficiency of the shock, i.e. its ability to accelerate particles to high energies, tends to be higher for those shock portions that are characterised by higher values of the scattering-centre compression ratio rc and/or the fast-mode Mach number MFM. At the same time, the acceleration efficiency can be strengthened by enhanced plasma density in the corresponding flux tube. The simulations show that protons can be accelerated to GLE energies in the shock portions characterised by the highest values of rc. Analysis of the delays between the flare onset and the production times of protons of 1 GV rigidity for different field lines in our simulations, and a subsequent comparison of those with the observed values indicate a possibility that quasi-perpendicular portions of the shock play the main role in producing relativistic protons.

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12

George, G. N., R. C. Bray, F. F. Morpeth und D. H. Boxer. „Complexes with halide and other anions of the molybdenum centre of nitrate reductase from Escherichia coli“. Biochemical Journal 227, Nr. 3 (01.05.1985): 925–31. http://dx.doi.org/10.1042/bj2270925.

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The interconversion of nitrate reductase from Escherichia coli between low-pH and high-pH Mo(V) e.p.r. signal-giving species was re-investigated [cf. Vincent & Bray (1978) Biochem. J. 171, 639-647]. The process cannot be described by a single pK value, since the apparent pK for interconversion is raised by the presence of various anions. The low-pH form of the enzyme exists as a series of complexes with different anion ligands of molybdenum. Each complex has specific and slightly different e.p.r. parameters, but all show strong coupling of Mo(V) to a single proton, exchangeable with the solvent, having A(1H)av. 1.0 to 1.3 mT. Complexes with Cl-, F- [A(19F)av. 0.7 mT], NO3- and NO2- give particularly well-defined spectra. The high-pH form of the enzyme is now shown to bear a coupled proton. Like that in the low-pH species, this proton is exchangeable with the solvent, but the coupling is much weaker, with A(1H)av. 0.3 mT. Thus, contrary to earlier assumptions, the proton detectable by e.p.r. is probably not identical with the proton whose dissociation controls interconversion between the two species; the latter proton could be located in the protein rather than on a ligand of molybdenum. Treatment of the enzyme with trypsin [Morpeth & Boxer (1985) Biochemistry 24, 40-46] did not affect its Mo(V) e.p.r. signals.

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13

Arnaldi, Ugo. „Hadrontherapy in the World and the Programmes of the Tera Foundation“. Tumori Journal 84, Nr. 2 (März 1998): 188–99. http://dx.doi.org/10.1177/030089169808400216.

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Hadrontherapy was born in 1938, when neutron beams were used in cancer therapy, but it has become an accepted therapeutical modality only in the last five years. Fast neutrons are still in use, even if their limitations are now apparent. Charged hadron beams are more favorable, since the largest specific energy deposition occurs at the end of their range in matter. The most used hadrons are at present protons and carbon ions. Both allow a dose deposition which conforms to the tumour target. Radiobiological experiments and the results of the first clinical trials indicate that carbon ions have, on top of this macroscopic property, a different way of interacting with cells at the microscopic level. There are thus solid hopes to use carbon beams of about 4500 MeV to control tumours which are radioresistant both to X-rays and protons. After discussing these macroscopic and microscopic properties of hadrontherapy, the hospital-based facilities, running or under construction, are reviewed. The conclusion is that, while in USA and Japan twelve of these centres will be running around the year 2001, in Europe very little is foreseen to use hadrontherapy to treat deep-seated tumours. The most advanced programme is the Italian one, which is described in the last Sections of the report. The main activities concern the construction, near Milano, of a centre for protons and carbon ions called CNAO (National Centre for Oncological Hadrontherapy) and the development of new type of proton accelerators. The Istituto Superiore di Sanità in Rome obtained the initial financing for constructing, in collaboration with ENEA, a 3 GHz linac, which eventually will accelerate protons to 200 MeV, so as to allow deep protontherapy. These, and other hadrontherapy centres in Italy and Europe, will be connected with oncology centres, hospitals and clinics by a multimedial network called RITA, so that before referral each patient's case can be discussed directly by doctors, even located far away, with the experts sitting in the hadrontherapy centres.

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Zimmer, Oliver, Hélène M. Jouve und Heinrich B. Stuhrmann. „Polarized proton spin density images the tyrosyl radical locations in bovine liver catalase“. IUCrJ 3, Nr. 5 (29.07.2016): 326–40. http://dx.doi.org/10.1107/s205225251601054x.

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A tyrosyl radical, as part of the amino acid chain of bovine liver catalase, supports dynamic proton spin polarization (DNP). Finding the position of the tyrosyl radical within the macromolecule relies on the accumulation of proton polarization close to it, which is readily observed by polarized neutron scattering. The nuclear scattering amplitude due to the polarization of protons less than 10 Å distant from the tyrosyl radical is ten times larger than the amplitude of magnetic neutron scattering from an unpaired polarized electron of the same radical. The direction of DNP was inverted every 5 s, and the initial evolution of the intensity of polarized neutron scattering after each inversion was used to identify those tyrosines which have assumed a radical state. Three radical sites, all of them close to the molecular centre and the haem, appear to be equally possible. Among these is tyr-369, the radical state of which had previously been proven by electron paramagnetic resonance.

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Csontos, Ágnes Anna, Bálint Fekete, Katalin Lőrinczy, Orsolya Terjék, Lajos Berczi, Márk Juhász, Pál Miheller und Zsolt Tulassay. „Prevalence of gastric polypoid lesions in a single endoscopic centre“. Orvosi Hetilap 154, Nr. 20 (Mai 2013): 770–74. http://dx.doi.org/10.1556/oh.2013.29617.

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Background: The prevalence of gastric polyps is unknown in Hungary. Aim: The aim of the authors was to assess the prevalence of polypoid lesions of the stomach in the endoscopic centre of the 2nd Department of Medicine, Semmelweis University. Methods: Results of upper gastrointestinal endoscopies carried out between March 2010 and June 2011 were analysed. Results: 193 cases with polyps were diagnosed in 4174 endoscopies (4.62%). Hyperplastic polyps, fundic gland polyps and malignant lesion were detected in 33.67%, 31.09% and 2.07% of the cases, respectively. Proton pump inhibitor use was more frequent among patients diagnosed with fundus gland polyps (p = 0.007), while hyperplastic polyps were diagnosed more frequently in patients with chronic gastritis (p = 0.032). Conclusions: The frequency of gastric polyps was higher than expected from data published in the literature. Long-term proton pump-inhibitor use and chronic gastritis were associated with fundus gland and hyperplastic polyps, respectively. Orv. Hetil., 2013, 154, 770–774.

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Noguchi, Takumi. „FTIR detection of water reactions in the oxygen-evolving centre of photosystem II“. Philosophical Transactions of the Royal Society B: Biological Sciences 363, Nr. 1494 (25.10.2007): 1189–95. http://dx.doi.org/10.1098/rstb.2007.2214.

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Flash-induced Fourier transform infrared (FTIR) difference spectroscopy has been used to study the water-oxidizing reactions in the oxygen-evolving centre of photosystem II. Reactions of water molecules were directly monitored by detecting the OH stretching bands of weakly H-bonded OH of water in the 3700–3500 cm −1 region in FTIR difference spectra during S-state cycling. In the S 1 →S 2 transition, a band shift from 3588 to 3617 cm −1 was observed, indicative of a weakened H-bond. Decoupling experiments using D 2 O : H 2 O (1 : 1) showed that this OH arose from a water molecule with an asymmetric H-bonding structure and this asymmetry became more significant upon S 2 formation. In the S 2 →S 3 , S 3 →S 0 and S 0 →S 1 transitions, negative bands were observed at 3634, 3621 and 3612 cm −1 , respectively, representing formation of a strong H-bond or a proton release reaction. In addition, using complex spectral features in the carboxylate stretching region (1600–1300 cm −1 ) as ‘fingerprints’ of individual S-state transitions, pH dependency of the transition efficiencies and the effect of dehydration were examined to obtain the information of proton release and water insertion steps in the S-state cycle. Low-pH inhibition of the S 2 →S 3 , S 3 →S 0 and S 0 →S 1 transitions was consistent with a view that protons are released in the three transitions other than S 1 →S 2 , while relatively high susceptibility to dehydration in the S 2 →S 3 and S 3 →S 0 transitions suggested the insertion of substrate water into the system during these transitions. Thus, a possible mechanism of water oxidation to explain the FTIR data is proposed.

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Orecchia, Roberto, und Marco Krengli. „Number of Potential Patients to be Treated with Proton Therapy in Italy“. Tumori Journal 84, Nr. 2 (März 1998): 205–8. http://dx.doi.org/10.1177/030089169808400218.

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In radiotherapy, the use of proton beams is one of the most promising approaches in order to reduce the treatment volume and, consenquently, increase the total dose avoiding severe complications to the normal tissues surrounding the target. Among the new hospital-based facilities that are planned for the next future, the italian project is in an advanced stage of study. Because of the complexity and high cost of the italian centre, one of the most important information in order to establish the cost/benefit balance, is represented by the number of potential patients to be treated for the various pathologies. For this reason it is useful to define a priority scale of clinical indications and, on this basis, to estimate the yearly patient afflux to the center, taking into account the incidence and the expected new cases to be treated with protons. Indications have been divided into two categories, according to decreasing priority. Category A includes all the tumors in which the use of proton therapy has clearly demonstrated to be advantageous, being the only way to give a curative dose to the target. In Italy, the extimated number of this category of patients is 825 each year. Category B comprises a great variety of tumors characterized mainly by a local evolution, with a limited likelihood of distant spread, and therefore potentially cured if the local control can be obtained. The total number of potential patients in this category is more than 10,000.

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Obini, Halima Ugomma. „Electron-proton interaction in radio sources“. Proceedings of the International Astronomical Union 15, S356 (Oktober 2019): 409. http://dx.doi.org/10.1017/s1743921320003634.

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AbstractA method of treating electron-proton interaction is presented. The energies involved in the interaction are estimated. Only elastic collisions are considered. The cross sections of the processes are not taken into account. Calculations are carried out in the centre of mass frame. Relevant quantities are transformed into the laboratory frame. Results indicate that the energy per collision gained by an electron ranges from 0.5 MeV to 0.6 MeV, under suitable conditions.

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Ramli, Sevarianus, Jehunias L. Tanesib und Albert Zicko Johannes. „PEMODELAN DUA DIMENSI MENGGUNAKAN RESIDUAL ANOMALI MAGNETIK LOKASI SAINS CENTER DI DESA OELNASI, KECAMATAN KUPANG TENGAH, KABUPATEN KUPANG“. Jurnal Fisika : Fisika Sains dan Aplikasinya 2, Nr. 2 (15.12.2018): 75–84. http://dx.doi.org/10.35508/fisa.v2i2.548.

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ABSTRAK Telah dilakukan penelitian dengan metode geomagnet pada lokasi Sains Center di Desa Oelnasi, Kecamatan Kupang Tengah, Kabupaten Kupang. Penelitian ini bertujuan untuk menginterpretasi kondisi bawah permukaan lokasi pembangunan gedung Sains Center dan memetakan pola perlapisan batuan bawah permukaan di lokasi penelitian. Pengambilan data dilakukan pada 192 titik ukur dengan luas lokasi ± 50 Ha. Proses akusisi data dengan sistem looping menggunakan alat Proton Prosession Magnetometer (PPM) tipe GSM-19T. Hasil penelitian menunjukkan sebaran nilai intensitas medan magnetik total dari 45255.85 nT sampai 45517.70 nT. Untuk anomali hasil pengolahan data diperoleh pada kisaran -90 nT sampai 190 nT. Hasil pemodelan 2 dimensi menunjukkan bahwa lokasi penelitian didominasi oleh batuan gamping dengan kisaran nilai suseptibilitas 0,000002 cgs unit sampai 0,002778 cgs unit dan berada pada kedalaman ±0 meter – 20 meter dan batuan diamagnetik dengan kisaran nilai suseptibilitas -0,000013 cgs unit sampai -0,000840 cgs unit pada kedalaman ± 5 meter – 20 meter. Kata kunci: Geomagnet, Suseptibilitas, Sains Center, Batuan gamping, Batuan diamagnetik. ABSTRACT A research has been done with used geomagnetic method in located science centre of oelnasi village subdistric kupang centre, kupang regency. This research purposes for interpretation under surface condition site the building of science centre and mapped pattern rock layered under surface in the location research. Acquire data to do in 192 drop measure with wide located ± 50 hectare. The acquire process with looping system make use of Proton Prosession Magnetometer (PPM) type GSM-19T. Output research showed value spread total intensity magnetic field as of 45255,85 nT to 45517,70 nT. For output anomaly data processing get to turn -90 nT to 190 nT. Two dimantion output modeling showed that in the location research predominance of limestones rock with the susceptibility value 0,000002 cgs unit to 0,002778 cgs unit and be in the depth ±0 meters – 20 meters, and diamagnetic rock with the susceptibility value -0,000013 cgs unit to 0,000840 cgs unit be in the depth ±5 meters – 20 meters. Keywords : Geomagnetic, Susceptibility, Science Centre, Limestone Rock, Diamagnetic Rock.

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Mistry, P., I. Gomez-Morilla, G. W. Grime, R. Webb, C. Jeynes, R. Gwilliam, A. Cansell, M. Merchant und K. J. Kirkby. „Proton beam lithography at the University of Surrey’s Ion Beam Centre“. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 242, Nr. 1-2 (Januar 2006): 387–89. http://dx.doi.org/10.1016/j.nimb.2005.08.128.

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Siao, Wei, Devrim Coskun, František Baluška, Herbert J. Kronzucker und Weifeng Xu. „Root-Apex Proton Fluxes at the Centre of Soil-Stress Acclimation“. Trends in Plant Science 25, Nr. 8 (August 2020): 794–804. http://dx.doi.org/10.1016/j.tplants.2020.03.002.

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Aurand, B., M. Hansson, L. Senje, K. Svensson, A. Persson, D. Neely, O. Lundh und C. G. Wahlström. „A setup for studies of laser-driven proton acceleration at the Lund Laser Centre“. Laser and Particle Beams 33, Nr. 1 (19.12.2014): 59–64. http://dx.doi.org/10.1017/s0263034614000779.

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AbstractWe report on a setup for the investigation of proton acceleration in the regime of target normal sheath acceleration. The main interest here is to focus on stable laser beam parameters as well as a reliable target setup and diagnostics in order to do extensive and systematic studies on the acceleration mechanism. A motorized target alignment system in combination with large target mounts allows for up to 340 shots with high repetition rate without breaking the vacuum. This performance is used to conduct experiments with a split mirror setup exploring the effect of spatial and temporal separation between the pulses on the acceleration mechanism and on the resulting proton beam.

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Hope, AB, J. Liggins und DB Matthews. „The Kinetics of Reactions in and Near the Cytochrome b/f Complex of Chloroplast Thylakoids. I. Proton Deposition“. Functional Plant Biology 15, Nr. 5 (1988): 695. http://dx.doi.org/10.1071/pp9880695.

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The kinetics of proton deposition in the intrathylakoid spaces of pea chloroplasts were measured under a wide range of conditions. With duroquinol added to reduce the plastoquinone pool, and 3-(3,4-dichlorophenyl)-1,1-dimethylurea added to inhibit photosystem II, but no ionophore present, the proton deposition, attributed to plastoquinol oxidation, was biphasic. About half the deposition had an apparent rate constant (k) of 150-200 s-1, the other half about 10 s-1. Valinomycin or nonactin (<0.1 �M) plus potassium ions made the deposition almost monophasic, with k = 140 s-1. When the state of reduction of the plastoquinone pool was varied by the addition of varied concentrations of duroquinol, in the presence of 1 �M nonactin, k for proton deposition varied from about 20 (0.01 mM duroquinol) up to a maximum of 140 s-1 (0.5 mM duroquinol). When temperature was varied between 4 and 23°C, with 1 �M nonactin, an Arrhenius plot of ln(k) for proton deposition was linear; the activation enthalpy was 67 kJ mol-1, the entropy of activation, 23 J K-1 mol-1. The data are analysed in terms of a bimolecular reaction between a varying concentration of plastoquinol and a fixed concentration of oxidised Rieske centre. The results are consistent with a rate constant, for the first electron donation by plastoquinol, of 28 s-1 (the rate-limiting step), followed by a relatively fast second electron donation to cytochrome b563 (low potential), followed by deposition of two protons. The speed of the second proton deposition is dependent on the membrane potential difference.

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Iqbal, Khalid, Qurat-ul-ain Shamsi, Kent A. Gifford, Sania Anum und Saeed Ahmad Buzdar. „A dosimetric analysis of proton beam therapy using different snouts“. Journal of Radiotherapy in Practice 18, Nr. 02 (23.11.2018): 180–85. http://dx.doi.org/10.1017/s1460396918000675.

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AbstractPurposeThis exploration is intended to analyse the dosimetric characteristics of proton beams of multiple energies using different snout sizes.Materials and methodsA synchrotron was used for the extraction of eight proton beam energies (100–250 MeV). Dosimetric measurements were taken in a water phantom that was irradiated with a proton beam emanating from the gantry system at angles 0, 90, 180 and 270 degree using a large and a medium snout. The range of beam energies in the phantom, their corresponding centre modulation depth (CMD) and the width of spread out Bragg peak (SOBP) were measured by Markus chamber. Double scattering technique was employed for the creation of SOBPs.ResultsThe range of proton beams varied from 4·3 cm for 100 MeV beam to 28·5 cm for 250 MeV beam with the medium snout and from 4·3 cm for 100 MeV to 25 cm for 250 MeV beam with large snout in the water phantom. SOBP width showed a variation from 4 to 10 cm with medium and large snout. While determining the output with medium snout, the discrepancy of 1·1% was observed between the maximum and minimum mean values of output for all the given set of energies and angles. There occurred a difference of 0·9% between the maximum and minimum mean values of output with the large snout. Beam output at SOBP centre was 12% higher with large snout as compared to that with medium snout for all the given beam energies. Flatness and symmetry were found within ±2·5% tolerance limits with medium and large snouts.ConclusionFlatness and symmetry were found within explicit limits with both medium and large snouts. Large snout produced higher beam output than that of medium snout at the centre of SOBP. This exploration can be extended to the determination of beam output, flatness and symmetry with a small snout.

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Pignol, Jean-Philippe, und Jakobus Slabbert. „Recoil proton, alpha particle, and heavy ion impacts on microdosimetry and RBE of fast neutrons: analysis of kerma spectra calculated by Monte Carlo simulation“. Canadian Journal of Physiology and Pharmacology 79, Nr. 2 (01.02.2001): 189–95. http://dx.doi.org/10.1139/y00-088.

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Fast neutrons (FN) have a higher radio-biological effectiveness (RBE) compared with photons, however the mechanism of this increase remains a controversial issue. RBE variations are seen among various FN facilities and at the same facility when different tissue depths or thicknesses of hardening filters are used. These variations lead to uncertainties in dose reporting as well as in the comparisons of clinical results. Besides radiobiology and microdosimetry, another powerful method for the characterization of FN beams is the calculation of total proton and heavy ion kerma spectra. FLUKA and MCNP Monte Carlo code were used to simulate these kerma spectra following a set of microdosimetry measurements performed at the National Accelerator Centre. The calculated spectra confirmed major classical statements: RBE increase is linked to both slow energy protons and alpha particles yielded by (n,α) reactions on carbon and oxygen nuclei. The slow energy protons are produced by neutrons having an energy between 10 keV and 10 MeV, while the alpha particles are produced by neutrons having an energy between 10 keV and 15 MeV. Looking at the heavy ion kerma from <15 MeV and the proton kerma from neutrons <10 MeV, it is possible to anticipate y* and RBE trends.Key words: fast neutron, kerma, microdosimetry, RBE, Monte Carlo.

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Javurkova, Martina. „The Fast Simulation Chain in the ATLAS experiment“. EPJ Web of Conferences 251 (2021): 03012. http://dx.doi.org/10.1051/epjconf/202125103012.

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The ATLAS experiment relies heavily on simulated data, requiring the production of billions of simulated proton-proton collisions every run period. As such, the simulation of collisions (events) is the single biggest CPU resource consumer. ATLAS’s finite computing resources are at odds with the expected conditions during the High Luminosity LHC era, where the increase in proton-proton centre-of-mass energy and instantaneous luminosity will result in higher particle multiplicities and roughly five-fold additional interactions per bunch-crossing with respect to LHC Run-2. Therefore, significant effort within the collaboration is being focused on increasing the rate at which Monte Carlo events can be produced by designing and developing fast alternatives to the algorithms used in the standard Monte Carlo production chain.

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Palmans, Hugo, Russell Thomas und Andrzej Kacperek. „Ion recombination correction in the Clatterbridge Centre of Oncology clinical proton beam“. Physics in Medicine and Biology 51, Nr. 4 (01.02.2006): 903–17. http://dx.doi.org/10.1088/0031-9155/51/4/010.

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Cohilis, Pascal, und Yves Jongen. „Some factors influencing the cost of a hospital based proton therapy centre“. Strahlentherapie und Onkologie 175, S2 (Juni 1999): 102–4. http://dx.doi.org/10.1007/bf03038904.

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Ajithkumar, T., A. L. Mazhari, M. Stickan-Verfürth, P. H. Kramer, C. S. Fuentes, J. Lambert, H. Thomas, H. Müller, G. Fleischhack und B. Timmermann. „Proton Therapy for Craniopharyngioma — An Early Report from a Single European Centre“. Clinical Oncology 30, Nr. 5 (Mai 2018): 307–16. http://dx.doi.org/10.1016/j.clon.2018.01.012.

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Churchill, Doreen, Julian M. Dust und Erwin Buncel. „Concerted rate-limiting proton transfer to sulfur with nucleophilic attack at phosphorus — A new proposed mechanism for hydrolytic decomposition of the P=S pesticide, Diazinon, in moderately acidic sulfuric acid media“. Canadian Journal of Chemistry 85, Nr. 6 (01.06.2007): 421–31. http://dx.doi.org/10.1139/v07-049.

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We report herein the first kinetic study of a P=S containing organophosphorus pesticide, Diazinon (1), in the moderately concentrated acid region. Product analyses (31P NMR) show that reaction occurs only at the P centre. The rate-acidity profile (kobs vs. molarity of H2SO4) appears as a curve in which the initial slight downward trace (molarity = 1 to ca. 5) is followed by sharper upward curve (molarity ca. 5 to 14). Using treatments involving the excess acidity (X) method, the A-1 and A-2 mechanistic possibilities were found to be inoperative over the full acidity range. A novel mechanism is proposed for the higher acidity (X ca. 2–6) region. This mechanism involves proton transfer to P=S from hydronium ion with concomitant proton transfer from water, which effectively delivers hydroxide to the P centre in a variant of the A-SE2 process. A putative A-2 mechanism in this region is supplanted by the proposed A-SE2 variant where the cyclic array results in proton transfer being efficiently coupled with nucleophilic attack involving water. This constitutes the first report of rate-limiting proton transfer at the P=S functionality in acid hydrolysis of this class of organophosphorus neutroxins. A 600 000-fold acceleration in the decomposition of Diazinon is associated with the change of medium from neutral aqueous solution to the most acidic medium studied (X ca. 6). Key words: phosphorothioate ester hydrolysis, acid catalysis, rate-limiting proton transfer at P=S, excess acidity analysis, new A-SE2 variant mechanism.

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Duscher, R., und J. K. Maichle. „Electronic Structure of a Single Hydrogen Centre in Magnesium Crystals“. Zeitschrift für Naturforschung A 40, Nr. 5 (01.05.1985): 433–38. http://dx.doi.org/10.1515/zna-1985-0501.

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In the present work, the problem “hydrogen storage in metals” is treated with the aid of the so-called New Tamm-Dancoff (NTD) procedure. We employ this method in lowest approximation for the evaluation of the electronic energy difference eigenvalue between a metal crystal with and without hydrogen centre. As an example we use Magnesium with hexagonal structure. For this system we calculate the difference eigenvalue with dependence on the displacement of the nearest neighbours and next nearest neighbours of the hydrogen centre, respectively. Finally we calculate the radial electron density distribution in the environment of the proton.

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McKENZIE, J. F., E. DUBININ und K. SAUER. „Nonlinear waves propagating transverse to the magnetic field“. Journal of Plasma Physics 65, Nr. 3 (April 2001): 213–33. http://dx.doi.org/10.1017/s0022377801001076.

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We generalize the classical work of Adlam and Allen [Phil. Mag.3, 448 (1958)] on solitons in a cold plasma propagating perpendicular to the magnetic field to include the effects of plasma pressure. This is done by making extensive use of the properties of total momentum conservation (denoted by the term ‘momentum hodograph’, since it yields a locus in the plane of the electron and proton speeds in the direction of the wave) and the energy integral of the system as a whole. These relations elucidate the phase and integral curves of stationary flows, from which soliton solutions may be constructed. In general, only compressive solitons are permitted, and we have found an analytical expression for the critical fast Mach number as a function of the proton acoustic Mach number, which shows that it varies from its classical value of 2 (at large proton acoustic Mach numbers) to unity, where the incoming flow is proton-sonic. At the critical fast Mach number, two possible soliton-like solutions can be constructed. One is the classical compression, in which the magnetic field develops a cusp in the centre of the wave. The other is a compression in the magnetic field followed by a deep depression in the centre of the wave, which is completed by the mirror image of this signature of compression–rarefaction. This structure involves a smooth supersonic–subsonic transition in the proton flow. For Mach numbers in excess of the critical one, this kind of structure can also be constructed, but now the magnetic field is cusp-like at the points of maximum compression.

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Narayana, Ponnada A., Jerry S. Wolinsky, Sajja B. Rao, Renjie He und Meghana Mehta. „Multicentre proton magnetic resonance spectroscopy imaging of primary progressive multiple sclerosis“. Multiple Sclerosis Journal 10, Nr. 3_suppl (Mai 2004): S73—S78. http://dx.doi.org/10.1191/1352458504ms1035oa.

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Multicentre baseline proton magnetic resonance spectro scopic data on primary progressive multiple sclerosis (PPMS) patients are acquired and analysed, using automatic analysis software. The metabolite ratios did not differ from centre to centre. The average N-acetylaspar tate/creatine (NA A/C r) ratio in PPMS was significantly lower compared to normal controls. No significant differences were observed in this ratio between lesion-containing regions (LC R) and normal-appearing tissues (NAT). Strong lipid resonances, even in the absence of lesions, are observed in the both grey and white matter in these patients. These observations suggest extensive diffuse and/or microscopic pathology in PPMS. No significant correlation between any of the metabolite ratios and the Extended Disability Scale Score (EDSS) or with other MR measures such as lesion burden and enhancement volumes is observed.

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Straessner, Arno. „HIGHLIGHTS FROM THE LHC“. Acta Polytechnica 53, A (18.12.2013): 518–23. http://dx.doi.org/10.14311/ap.2013.53.0518.

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The Large Hadron Collider (LHC) and the two multi-purpose detectors, ATLAS and CMS, have been operated successfully at record centre-of-mass energies of 7 ÷ 8TeV. This paper presents the main physics results from proton–proton collisions based on a total luminosity of 2 × 5 fb<sup>−1</sup>. The most recent results from Standard Model measurements, Standard Model and MSSM Higgs searches, as well as searches for supersymmetric and exotic particles are reported. Prospects for ongoing and future data taking are presented.

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DASKALAKIS, GEORGIOS. „CMS ECAL PERFORMANCE - TESTBEAM RESULTS“. International Journal of Modern Physics A 20, Nr. 16 (30.06.2005): 3823–25. http://dx.doi.org/10.1142/s0217751x05027722.

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The Compact Muon Solenoid (CMS) experiment is a general-purpose detector designed to explore the physics of proton-proton collisions at a centre-of-mass energy of 14 TeV over the full range of luminosities expected at the Large Hadron Collider (LHC). The Electromagnetic Calorimeter (ECAL) will play an essential role in the study of the electroweak symmetry breaking, particularly through the exploration of the Higgs boson sector. To evaluate its characteristics, an ECAL prototype was placed in an electron testbeam at CERN. Highlights of results obtained during the test beam campaign are presented.

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Meepripruk, Montha, und Kenneth J. Haller. „Reinvestigation of tricyclic acyclovir: characterization of a `proton-wire' model“. Acta Crystallographica Section C Crystal Structure Communications 69, Nr. 9 (21.08.2013): 1077–80. http://dx.doi.org/10.1107/s0108270113021082.

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The crystal structure of a dihydrate of the title compound, 3-[(2-hydroxyethoxy)methyl]-6-methyl-3H-imidazolo[1,2-a]-purin-9(5H)-one, C11H13N5O3·2H2O, has been reinvestigated. The asymmetric unit contains two molecules of tricyclic acyclovir and four molecules of water. The structure consists of a three-dimensional network of strong hydrogen bonds that integrates all of the components. While the crystal structure and the formation of an (H2O)8solvent water molecule cluster through a disordered strong hydrogen bond [O...O = 2.807 (3) Å] between two water molecules across an inversion centre has been described previously [Suwińska, Golankiewicz & Zielenkiewicz (2001).Acta Cryst.C57, 767–769], the disorder was incompletely modelled. In this work, the disorder model is extended and includes disorder of one tricyclic acyclovir hydroxy group across another inversion centre [O...O = 2.644 (4) Å]. The resulting infinite O—H...O hydrogen-bonded water–hydroxy chains, analogous to the `proton wires' found in the membrane protein gramicidin A, are discussed and an unusual disorder model involving infinite concerted chains of O—H...O hydrogen bonds is provided.

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Barisonzi, Marcello. „QCD and Top physics studies in proton-proton collisions at 7 TeV centre-of-mass energy with the ATLAS detector“. Journal of Physics: Conference Series 347 (14.02.2012): 012032. http://dx.doi.org/10.1088/1742-6596/347/1/012032.

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38

Kanowski, Martin, Jürgen Voges und Claus Tempelmann. „Delineation of the Nucleus Centre Median by Proton Density Weighted Magnetic Resonance Imaging at 3 T“. Operative Neurosurgery 66, suppl_1 (01.03.2010): ons—E121—ons—E123. http://dx.doi.org/10.1227/01.neu.0000348560.85056.63.

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Abstract Objective: To demonstrate that proton density weighted magnetic resonance imaging (MRI) at 3 T accomplishes delineation of the centre median (CM) complex from surrounding thalamic tissue and may improve targeting accuracy in stereotactic neurosurgery. Methods: Five healthy subjects (1 man, 4 women; age range 22–35 years) underwent high-resolution MRI at 3 T with different imaging parameters in order to optimize the direct visualization of the CM. Results: In healthy subjects, the CM complex of the thalamus can be reliably contrasted on axially oriented slices by means of proton density weighted turbo-spin-echo MRI. An in-plane resolution of at least 0.6 × 0.6 mm2 is crucial at a slice thickness between 2 and 3 mm. Effective suppression of head motion is essential. Conclusion: MRI-based delineation of the CM could have therapeutic potential to facilitate target determination for neuromodulation in stereotactic neurosurgery.

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Chen, Zhe, Masayuki Araya und Hiroshi Onishi. „Proton beam therapy for malignant transformation of intracranial epidermoid cyst“. BMJ Case Reports 12, Nr. 7 (Juli 2019): e229388. http://dx.doi.org/10.1136/bcr-2019-229388.

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We report the first clinical case on the successful use of proton beam therapy in the management of malignant transformation of intracranial epidermoid cyst. A 43-year-old man was initially diagnosed as this disease with left facial paresis, hypesthesia and hypoalgesia in the territories of the trigeminal nerve. After failure of surgical interventions, he was referred to our radiation centre. We performed a postoperative proton beam therapy for treatment. We delivered a total dose of 57 GyE in 31 fractions. He tolerated the treatment well with mild acute toxicities and remained healthy and functional by 2-year follow-up postradiotherapy. No evidence of delayed radiation-induced neurotoxicity was observed.

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Rico-Gutiérrez, T., L. Gómez-Sayago, L. García López, P. Hidalgo-Collazos und M. Criado Illana. „PS-126 The rational use of proton pump inhibitors in a geriatric centre“. European Journal of Hospital Pharmacy 22, Suppl 1 (März 2015): A186.1—A186. http://dx.doi.org/10.1136/ejhpharm-2015-000639.447.

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Aitkenhead, A. H., D. Bugg, C. G. Rowbottom, E. Smith und R. I. Mackay. „Modelling the throughput capacity of a single-accelerator multitreatment room proton therapy centre“. British Journal of Radiology 85, Nr. 1020 (Dezember 2012): e1263-e1272. http://dx.doi.org/10.1259/bjr/27428078.

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42

Guardiola, Consuelo, Ludovic De Marzi und Yolanda Prezado. „Verification of a Monte Carlo dose calculation engine in proton minibeam radiotherapy in a passive scattering beamline for preclinical trials“. British Journal of Radiology 93, Nr. 1107 (März 2020): 20190578. http://dx.doi.org/10.1259/bjr.20190578.

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Objectives: Proton minibeam radiation therapy (pMBRT) is a novel therapeutic strategy that combines the benefits of proton therapy with the remarkable normal tissue preservation observed with the use of submillimetric spatially fractionated beams. This promising technique has been implemented at the Institut Curie-Proton therapy centre (ICPO) using a first prototype of a multislit collimator. The purpose of this work was to develop a Monte Carlo-based dose calculation engine to reliably guide preclinical studies at ICPO. Methods: The whole “Y1”-passive beamline at the ICPO, including pMBRT implementation, was modelled using the Monte Carlo GATE v. 7.0 code. A clinically relevant proton energy (100 MeV) was used as starting point. Minibeam generation by means of the brass collimator used in the first experiments was modelled. A virtual source was modelled at the exit of the beamline nozzle and outcomes were compared with dosimetric measurements performed with EBT3 gafchromic films and a diamond detector in water. Dose distributions were recorded in a water phantom and in rat CT images (7-week-old male Fischer rats). Results: The dose calculation engine was benchmarked against experimental data and was then used to assess dose distributions in CT images of a rat, resulting from different irradiation configurations used in several experiments. It reduced computational time by an order of magnitude. This allows us to speed up simulations for in vivo trials, where we obtained peak-to-valley dose ratios of 1.20 ± 0.05 and 6.1 ± 0.2 for proton minibeam irradiations targeting the tumour and crossing the rat head. Tumour eradication was observed in the 67 and 22% of the animals treated respectively. Conclusion: A Monte Carlo dose calculation engine for pMBRT implementation with mechanical collimation has been developed. This tool can be used to guide and interpret the results of in vivo trials. Advances in knowledge: This is the first Monte Carlo dose engine for pMBRT that is being used to guide preclinical trials in a clinical proton therapy centre.

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Copolovici, Lucian, Richard A. Varga, Vito Lippolis und Cristian Silvestru. „Hydrogen bis(tetraphenylimidodiphospinic acid) triiodide“. Acta Crystallographica Section E Structure Reports Online 63, Nr. 11 (03.10.2007): o4206—o4207. http://dx.doi.org/10.1107/s1600536807047198.

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In the crystal structure of the title compound, [(C24H21NO2P2)2H]+·I3 −, the triiodide anion is linear, sitting across a centre of symmetry, with I—I distances of 2.9130 (6) Å. The [H{(OPPh2)2NH}2]+ cation is formed by two symmetry-related molecules of tetraphenylimidodiphosphinic acid, (OPPh2)2NH, exbiting for the O—P—N—P—O skeleton an anti conformation [code (−,+)/(+,−)] with an angular P—N—P fragment. The charge is determined by a single proton shared by these two molecules, disordered across a centre of symmetry and forming an O—H...O hydrogen bond.

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Mulkidjanian, A. Y., M. A. Kozlova und D. A. Cherepanov. „Ubiquinone reduction in the photosynthetic reaction centre of Rhodobacter sphaeroides: interplay between electron transfer, proton binding and flips of the quinone ring“. Biochemical Society Transactions 33, Nr. 4 (01.08.2005): 845–50. http://dx.doi.org/10.1042/bst0330845.

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This review is focused on reactions that gate (control) the electron transfer between the primary quinone QA and secondary quinone QB in the photosynthetic reaction centre of Rhodobacter sphaeroides. The results on electron and proton transfer are discussed in relation to structural information and to the steered molecular dynamics simulations of the QB ring flip in its binding pocket. Depending on the initial position of QB in the pocket and on certain conditions, the rate of electron transfer is suggested to be limited either by the quinone ring flip or by the charge-compensating proton equilibration between the surface and the buried QB site.

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Abdul Razak, Nurul Ellena, Morgan Madhuku, Ishaq Ahmad, Burhanuddin Yeop Majlis, Fu Dee Chang und Dilla Duryha Berhanuddin. „Structural and Photoluminescence Analysis on the Implantation of Carbon and Proton for the Creation of Damage-Assisted Emission in Silicon“. Sains Malaysiana 49, Nr. 12 (31.12.2020): 2927–36. http://dx.doi.org/10.17576/jsm-2020-4912-05.

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We study the induced defects in the depth profiling of the silicon structure after being implanted with carbon and followed by high energy proton irradiation. It has been reported before that the formation of the optically active point-defect, specifically the G-centre is due to the implantation and irradiation of carbon and proton, respectively. It is crucial to quantify the diffusional broadening of the implanted ion profile especially for proton irradiation process so that the radiation damage evolution can be maximized at the point-defect formation region. Profiling analysis was carried out using computational Stopping and Range of Ions in Matter (SRIM) and Surrey University Sputter Profile Resolution from Energy Deposition (SUSPRE) simulation. The energies of carbon ions adopted for this investigation are 10, 20, 30, and 50 keV, while proton irradiation energy was kept at 2 MeV. Photoluminescence measurements on silicon implanted with carbon at different energies were carried out to study the interrelation between the numbers of vacancies produced during the damage event and the peak emission intensities.

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Williams, Declan, Justin Kai-Chi Lau, Junfang Zhao, Stefanie Mädler, Yating Wang, Irine S. Saminathan, Alan C. Hopkinson und K. W. Michael Siu. „Radical-induced, proton-transfer-driven fragmentations in [b5 − H]˙+ ions derived from pentaalanyl tryptophan“. Physical Chemistry Chemical Physics 17, Nr. 16 (2015): 10699–707. http://dx.doi.org/10.1039/c5cp00178a.

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Capua, Marcella. „Top quark studies with the ATLAS detector“. International Journal of Modern Physics: Conference Series 39 (Januar 2015): 1560092. http://dx.doi.org/10.1142/s2010194515600927.

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The latest top quark studies in proton-proton collisions at a centre-of-mass energy of 7 and 8 TeV with the ATLAS detector are reported. We present recent results on the top pair production inclusive cross-sections, top pair production differential cross-section in the resolved and boosted regimes, single top-quark production cross-sections measured in the t-channel, s-channel and W-boson associated processes, as well as the determination of the CKM matrix element [Formula: see text]. The results are compared with theoretical expectations. Latest ATLAS results on top properties will be also shown in terms of direct and pole mass, spin correlations and charge asymmetry.

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Machado, Mairon M., und Magno V. T. Machado. „Total, Elastic and Single Diffractive Cross Sections for LHC Energies“. International Journal of Modern Physics: Conference Series 45 (Januar 2017): 1760062. http://dx.doi.org/10.1142/s201019451760062x.

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In this contribution we provide predictions for total, elastic and single diffractive cross sections calculated for the proton-proton collisions at the LHC in centre-of-mass energies of 0.9, 7, 8 and 14 TeV. We consider the framework of the Miettinen-Pumplin model which correctly describes the lower energy data available by Fermilab-Tevatron. Our predictions are based on the fitted parameters of the model for the Tevatron measurements and for TOTEM-LHC measurements at 7 TeV. We extrapolate the results for the higher energies runs of LHC and provide predictions for them. We verify that those prediction are in agreement with the recent CERN-ATLAS Collaboration result.

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SZUBA, DOROTA. „VECTOR MESON PRODUCTION AT HERA“. International Journal of Modern Physics A 20, Nr. 02n03 (30.01.2005): 436–44. http://dx.doi.org/10.1142/s0217751x05021609.

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The diffractive production of vector mesons ep→eVMY, with VM=ρ0, ω, ϕ, J/ψ, ψ′ or ϒ and with Y being either the scattered proton or a low mass hadronic system, has been extensively investigated at HERA. HERA offers a unique opportunity to study the dependences of diffractive processes on different scales: the mass of the vector meson, mVM, the centre-of-mass energy of the γp system, W, the photon virtuality, Q2 and the four-momentum transfer squared at the proton vertex, |t|. Strong interactions can be investigated in the transition from the hard to the soft regime, where the confinement of quarks and gluons occurs.

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Noda, Yohei, Takayuki Kumada, Takeji Hashimoto und Satoshi Koizumi. „Inhomogeneous dynamic nuclear polarization of protons in a lamella-forming diblock copolymer investigated by a small-angle neutron scattering method“. Journal of Applied Crystallography 44, Nr. 3 (14.05.2011): 503–13. http://dx.doi.org/10.1107/s0021889811013021.

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By combining two methods of selective doping of paramagnetic species into a microdomain and small-angle neutron scattering (SANS), thespatially inhomogeneous proton polarizationcreated by dynamic nuclear polarization (DNP) has been precisely evaluated. A lamella-forming diblock copolymer composed of polystyrene (PS) and polyisoprene (PI) block chains (PS-b-PI) was employed, the SANS profile of which clearly shows scattering peaks up to the third order due to interlamellar interference. As a source of electron spin for DNP, 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) was doped into one or other of the microdomains; samples with PS or PI microdomains selectively doped with TEMPO are designated PS.-b-PI and PS-b-PI., respectively. The SANS intensity at the first- and third-order peaks is well reproduced by assuming that the proton polarization is homogeneous throughout the sample, but that at the second-order peak cannot be explained by this assumption. This anomaly regarding the second-order peak was successfully explained by a model postulating that proton polarization in a doped microdomain decreases with increasing distance from the interface with a neighbouring doped microdomain. The decrease in proton polarization at the centre of a doped microdomain was estimated to be 0.07 (2) for PS-b-PI.and 0.05 (1) for PS.-b-PI, relative to constant proton polarization in a doped microdomain. The inhomogeneous proton polarization results from two competing dynamic processes,i.e.spin diffusion from doped to undoped microdomains, and spin lattice relaxation occurring on the pathway of proton spin diffusion.

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