1,716 research outputs found
Effects Of Non-parabolicity And In-plane Magnetic Fields On The Cyclotron Effective Mass And G -factor In Gaas-(ga,al)as Quantum Wells
The envelope-function approach is used to theoretically study the effects of in-plane magnetic fields on the cyclotron effective mass and LandĂ© g -factor associated to conduction electrons in single GaAs-(Ga,Al)As quantum wells. Non-parabolic and anisotropy effects are included in the calculations within the Ogg-McCombe effective Hamiltonian to describe the electron states in the semiconductor heterostructure. The electronic structure and both the cyclotron effective mass and LandĂ© g -factor were obtained, by expanding the corresponding envelope wave functions in terms of harmonic-oscillator wave functions, as functions of the in-plane magnetic field, cyclotron orbit-center position, and quantum-well widths. This procedure allows us to consider the different terms in the Hamiltonian on equal footing, avoiding therefore the use of approximate methods to obtain the envelope wave functions and the corresponding energy spectrum. Results obtained for the LandĂ© g -factor were found in quite good agreement with available experimental measurements. © 2006 The American Physical Society.738Bode, M., Getzlaff, M., Wiesendanger, R., (1998) Phys. Rev. Lett., 81, p. 4256. , PRLTAO 0031-9007 10.1103/PhysRevLett.81.4256Heinze, S., Bode, M., Kubetzka, A., Pietzsch, O., Nie, X., Blugel, S., Wiesendanger, R., (2000) Science, 288, p. 1805. , SCIEAS 0036-8075 10.1126/science.288.5472.1805Nussinov, Z., Crommie, M.F., Balatsky, A.V., (2003) Phys. Rev. B, 68, p. 085402. , PRBMDO 0163-1829 10.1103/PhysRevB.68.085402Nielsen, M.A., Chuang, I.L., (2000) Quantum Computation and Quantum Information, , Cambridge University Press, CambridgeSalis, G., Kato, Y.K., Ensslin, K., Driscol, D.C., Gossard, A.C., Awschalom, D.D., (2001) Nature, 414, p. 619. , NATUAS 0028-0836 10.1038/414619aZutic, I., Fabian, J., Das Sarma, S., (2004) Rev. Mod. Phys., 76, p. 323. , RMPHAT 0034-6861 10.1103/RevModPhys.76.323Engel, H.-A., Loss, D., (2005) Science, 309, p. 586. , SCIEAS 0036-8075 10.1126/science.1113203OsĂłrio, F.A.P., Degani, M.H., HipĂłlito, O., (1988) Phys. Rev. B, 38, p. 8477. , PRBMDO. 0163-1829. 10.1103/PhysRevB.38.8477Nicholas, R.J., Hopkins, M.A., Barnes, D.J., Brummell, M.A., Sigg, H., Heitmann, D., Ensslin, K., Weimann, G., (1989) Phys. Rev. B, 39, p. 10955. , PRBMDO 0163-1829 10.1103/PhysRevB.39.10955Huant, S., Mandray, A., Etienne, B., (1992) Phys. Rev. B, 46, p. 2613. , PRBMDO 0163-1829 10.1103/PhysRevB.46.2613Cole, B.E., Chamberlain, J.M., Henini, M., Cheng, T., Batty, W., Wittlin, A., Perenboom, J.A.A.J., Singleton, J., (1997) Phys. Rev. B, 55, p. 2503. , PRBMDO 0163-1829 10.1103/PhysRevB.55.2503Johnson, G.R., Kana-Ah, A., Cavenett, B.C., Skolnick, M.S., Baas, S.J., (1987) Semicond. Sci. Technol., 2, p. 182. , SSTEET 0268-1242 10.1088/0268-1242/2/3/010Dobers, M., Klitzing K, V., Weimann, G., (1988) Phys. Rev. B, 38, p. 5453. , PRBMDO 0163-1829 10.1103/PhysRevB.38.5453Snelling, M.J., Flinn, G.P., Plaut, A.S., Harley, R.T., Tropper, A.C., Eccleston, R., Phillips, C.C., (1991) Phys. Rev. B, 44, p. 11345. , PRBMDO 0163-1829 10.1103/PhysRevB.44.11345Heberle, A.P., RĂŒhle, W.W., Ploog, K., (1994) Phys. Rev. Lett., 72, p. 3887. , PRLTAO. 0031-9007. 10.1103/PhysRevLett.72.3887Hannak, R.M., Oestreich, M., Heberle, A.P., Ruhle, W.W., Kohler, K., (1995) Solid State Commun., 93, p. 313. , SSCOA4 0038-1098 10.1016/0038-1098(94)00784-5Le Jeune, P., Robart, D., Marie, X., Amand, T., Brosseau, M., Barrau, J., Kalevich, V., Rodichev, D., (1997) Semicond. Sci. Technol., 12, p. 380. , SSTEET 0268-1242 10.1088/0268-1242/12/4/006Malinowski, A., Harley, R.T., (2000) Phys. Rev. B, 62, p. 2051. , PRBMDO 0163-1829 10.1103/PhysRevB.62.2051Sapega, V.F., Ruf, T., Cardona, M., Ploog, K., Ivchenko, E.L., Mirlin, D.N., (1994) Phys. Rev. B, 50, p. 2510. , PRBMDO 0163-1829 10.1103/PhysRevB.50.2510Medeiros-Ribeiro, G., Pinheiro, M.V.B., Pimentel, V.L., Marega, E., (2002) Appl. Phys. Lett., 80, p. 4229. , APPLAB 0003-6951 10.1063/1.1483112Lindermann, S., Ihn, T., Heinzel, T., Zwerger, W., Ensslin, K., Maranowski, K., Gossard, A.C., (2002) Phys. Rev. B, 66, p. 195314. , PRBMDO 0163-1829 10.1103/PhysRevB.66.195314Hanson, R., Witkamp, B., Vandersypen, L.M.K., Willems Van Beveren, L.H., Elzerman, J.M., Kouwenhoven, L.P., (2003) Phys. Rev. Lett., 91, p. 196802. , PRLTAO 0031-9007 10.1103/PhysRevLett.91.196802Maude, D.K., Potemski, M., Portal, J.C., Henini, M., Eaves, L., Hill, G., Pate, M.A., (1996) Phys. Rev. Lett., 77, p. 4604. , PRLTAO 0031-9007 10.1103/PhysRevLett.77.4604Kato, Y.K., Myers, R.C., Driscol, D.C., Gossard, A.C., Levy, J., Awschalom, D.D., (2003) Science, 299, p. 1201. , SCIEAS 0036-8075 10.1126/science.1080880Kato, Y.K., Myers, R.C., Gossard, A.C., Awschalom, D.D., (2004) Science, 306, p. 1910. , SCIEAS 0036-8075 10.1126/science.1105514Bracker, A.S., Stinaff, E.A., Gammon, D., Ware, M.E., Tischler, J.G., Shabaev, A., Efros, A.L., Merkulov, I.A., (2005) Phys. Rev. Lett., 94, p. 047402. , PRLTAO 0031-9007 10.1103/PhysRevLett.94.047402Rashba, E.I., Efros, A.L., (2003) Phys. Rev. Lett., 91, p. 126405. , PRLTAO 0031-9007 10.1103/PhysRevLett.91.126405De Sousa, R., Das Sarma, S., (2003) Phys. Rev. B, 68, p. 155330. , PRBMDO 0163-1829 10.1103/PhysRevB.68.155330Prado, S.J., Trallero-Giner, C., Alcalde, A.M., Lopez-Richard, V., Marques, G.E., (2004) Phys. Rev. B, 69, p. 201310. , PRBMDO 0163-1829 10.1103/PhysRevB.69.201310Destefani, C.F., Ulloa, S.E., (2005) Phys. Rev. B, 71, p. 161303. , PRBMDO 0163-1829 10.1103/PhysRevB.71.161303Ogg, N.R., (1966) Proc. Phys. Soc. London, 89, p. 431. , PPSOAU 0370-1328 10.1088/0370-1328/89/2/326McCombe, B.O., (1969) Phys. Rev., 181, p. 1206. , PHRVAO 0031-899X 10.1103/PhysRev.181.1206Maan, J.C., (1987) Festkörperprobleme, 27, p. 137. , edited by P. Grosse. Advances in Solid State Physics, Vol. Vieweg, BraunschweigMaan, J.C., (1988) Surf. Sci., 196, p. 518. , SUSCAS 0039-6028 10.1016/0039-6028(88)90735-2Platero, G., Altarelli, M., (1989) Phys. Rev. B, 39, p. 3758. , PRBMDO 0163-1829 10.1103/PhysRevB.39.3758Braun, M., Rössler, U., (1985) J. Phys. C, 18, p. 3365. , JPSOAW. 0022-3719. 10.1088/0022-3719/18/17/013Golubev, V.G., Ivanov-Omskii, V.I., Minervin, I.G., Osutin, A.V., Polyakov, D.G., (1985) Sov. Phys. JETP, 61, p. 1214. , SPHJAR 0038-5646SabĂn Del Valle, J., LĂłpez-Gondar, J., De Dios-Leyva, M., (1989) Phys. Status Solidi B, 151, p. 127. , PSSBBD. 0370-1972Bruno-Alfonso, A., Diago-Cisneros, L., De Dios-Leyva, M., (1995) J. Appl. Phys., 77, p. 2837. , JAPIAU 0021-8979 10.1063/1.359540Li, E.H., (2000) Physica e (Amsterdam), 5, p. 215. , PELNFM 1386-9477 10.1016/S1386-9477(99)00262-3Hermann, C., Weisbuch, C., (1977) Phys. Rev. B, 15, p. 823. , PLRBAQ 0556-2805 10.1103/PhysRevB.15.823Dresselhaus, G., (1955) Phys. Rev., 100, p. 580. , PHRVAO 0031-899X 10.1103/PhysRev.100.580Casey Jr., R.C., (1978) J. Appl. Phys., 49, p. 3684. , JAPIAU 0021-8979 10.1063/1.325421Dingle, R., (1975) Festkörperprobleme XV, p. 21. , edited by H. J. Queisser. Pergamon, BraunschweigMiller, R.C., Kleinman, D.A., Gossard, A.C., (1984) Phys. Rev. B, 29, p. 7085. , PRBMDO 0163-1829 10.1103/PhysRevB.29.7085Wang, W., Mendez, E.E., Stern, F., (1984) Appl. Phys. Lett., 45, p. 639. , APPLAB 0003-6951 10.1063/1.95339Lommer, G., Malcher, F., Rössler, U., (1985) Phys. Rev. B, 32, p. 6965. , PRBMDO. 0163-1829. 10.1103/PhysRevB.32.6965Malcher, F., Lommer, G., Rössler, U., (1986) Superlattices Microstruct., 2, p. 267. , SUMIEK. 0749-6036. 10.1006/spmi.1996.0195Lommer, G., Malcher, F., Rössler, U., (1986) Superlattices Microstruct., 2, p. 273. , SUMIEK. 0749-6036. 10.1016/0749-6036(86)90031-5Kainz, J., Rössler, U., Winkler, R., (2003) Phys. Rev. B, 68, p. 075322. , PRBMDO. 0163-1829. 10.1103/PhysRevB.68.075322Könemann, J., Haug, R.J., Maude, D.K., Falko, V.I., Altshuler, B.L., (2005) Phys. Rev. Lett., 94, p. 226404. , PRLTAO. 0031-9007. 10.1103/PhysRevLett.94.226404D'Yakonov, M.I., Perel, V.I., (1971) Sov. Phys. Solid State, 13, p. 3023. , SPSSA7 0038-5654Kim, N., La Rocca, G.C., Rodriguez, S., (1989) Phys. Rev. B, 40, p. 3001. , PRBMDO 0163-1829 10.1103/PhysRevB.40.3001Das, B., Datta, S., Reifenberger, R., (1990) Phys. Rev. B, 41, p. 8278. , PRBMDO 0163-1829 10.1103/PhysRevB.41.827
Self-similarity And Anti-self-similarity Of The Effective Landé G Factor In Gaas-(ga,al)as Fibonacci Superlattices Under In-plane Magnetic Fields
A theoretical study of the effects of in-plane magnetic fields on the LandĂ© g factor associated to conduction electrons in GaAs-(Ga,Al)As Fibonacci superlattices is presented. We have used the Ogg-McCombe effective Hamiltonian, which includes nonparabolic and anisotropy effects, in order to describe the electron states in the Fibonacci heterostructure. We have expanded the corresponding electron envelope wave functions in terms of harmonic-oscillator wave functions, and obtained the LandĂ© g factor for magnetic fields related by even powers of the golden mean Ï=(1+5)2. Theoretical results for GaAs-(Ga,Al)As Fibonacci superlattices, under magnetic-field values scaled by Ï2n, clearly exhibit a self-similar (for even n) or anti-self-similar (for odd n) behavior for the LandĂ© g factors, as appropriate. © 2006 The American Physical Society.743Merlin, R., Bajema, K., Clarke, R., Juang, F.Y., Bhattacharya, P.K., (1985) Phys. Rev. Lett., 55, p. 1768. , PRLTAO 0031-9007 10.1103/PhysRevLett.55.1768Wang, Y.Y., Maan, J.C., (1989) Phys. Rev. B, 40, p. 1955. , PRBMDO 0163-1829 10.1103/PhysRevB.40.1955Toet, D., Potemski, M., Wang, Y.Y., Maan, J.C., Tapfer, L., Ploog, K., (1991) Phys. Rev. Lett., 66, p. 2128. , PRLTAO 0031-9007 10.1103/PhysRevLett.66.2128Maan, J.C., Chitta, V., Toet, D., Potemski, M., Ploog, K., (1992) Springer Series in Solid-State Sciences, 101, p. 549. , edited by G. Landwehr (Springer, BerlinBruno-Alfonso, A., Oliveira, L.E., De Dios-Leyva, M., (1995) Appl. Phys. Lett., 67, p. 536. , APPLAB 0003-6951 10.1063/1.115180Bruno-Alfonso, A., Reyes-GĂłmez, E., Oliveira, L.E., De Dios-Leyva, M., (1995) J. Appl. Phys., 78, p. 15. , JAPIAU. 0021-8979. 10.1063/1.360240De Dios-Leyva, M., Bruno-Alfonso, A., Reyes-GĂłmez, E., Oliveira, L.E., (1995) J. Phys.: Condens. Matter, 7, p. 9799. , JCOMEL. 0953-8984. 10.1088/0953-8984/7/50/014Nielsen, M.A., Chuang, I.L., (2000) Quantum Computation and Quantum Information, , Cambridge University Press, CambridgeSalis, G., Kato, Y.K., Ensslin, K., Driscol, D.C., Gossard, A.C., Awschalom, D.D., (2001) Nature (London), 414, p. 619. , NATUAS 0028-0836 10.1038/414619aZutic, I., Fabian, J., Das Sarma, S., (2004) Rev. Mod. Phys., 76, p. 323. , RMPHAT 0034-6861 10.1103/RevModPhys.76.323Engel, H.-A., Loss, D., (2005) Science, 309, p. 586. , SCIEAS 0036-8075 10.1126/science.1113203Hermann, C., Weisbuch, C., (1977) Phys. Rev. B, 15, p. 823. , PLRBAQ 0556-2805 10.1103/PhysRevB.15.823Le Jeune, P., Robart, D., Marie, X., Amand, T., Brosseau, M., Barrau, J., Kalevich, V., Rodichev, D., (1997) Semicond. Sci. Technol., 12, p. 380. , SSTEET 0268-1242 10.1088/0268-1242/12/4/006Malinowski, A., Harley, R.T., (2000) Phys. Rev. B, 62, p. 2051. , PRBMDO 0163-1829 10.1103/PhysRevB.62.2051Sapega, V.F., Ruf, T., Cardona, M., Ploog, K., Ivchenko, E.L., Mirlin, D.N., (1994) Phys. Rev. B, 50, p. 2510. , PRBMDO 0163-1829 10.1103/PhysRevB.50.2510Medeiros-Ribeiro, G., Pinheiro, M.V.B., Pimentel, V.L., Marega, E., (2002) Appl. Phys. Lett., 80, p. 4229. , APPLAB 0003-6951 10.1063/1.1483112Hanson, R., Witkamp, B., Vandersypen, L.M.K., Willems Van Beveren, L.H., Elzerman, J.M., Kouwenhoven, L.P., (2003) Phys. Rev. Lett., 91, p. 196802. , PRLTAO 0031-9007 10.1103/PhysRevLett.91.196802Rashba, E.I., Efros, A.L., (2003) Phys. Rev. Lett., 91, p. 126405. , PRLTAO 0031-9007 10.1103/PhysRevLett.91.126405De Sousa, R., Das Sarma, S., (2003) Phys. Rev. B, 68, p. 155330. , PRBMDO 0163-1829 10.1103/PhysRevB.68.155330Prado, S.J., Trallero-Giner, C., Alcalde, A.M., Lopez-Richard, V., Marques, G.E., (2004) Phys. Rev. B, 69, p. 201310. , PRBMDO 0163-1829 10.1103/PhysRevB.69.201310Destefani, C.F., Ulloa, S.E., (2005) Phys. Rev. B, 71, p. 161303. , PRBMDO 0163-1829 10.1103/PhysRevB.71.161303Ogg, N.R., (1966) Proc. Phys. Soc. London, 89, p. 431. , PPSOAU 0370-1328 10.1088/0370-1328/89/2/326McCombe, B.O., (1969) Phys. Rev., 181, p. 1206. , PHRVAO 0031-899X 10.1103/PhysRev.181.1206Braun, M., Rössler, U., (1985) J. Phys. C, 18, p. 3365. , JPSOAW. 0022-3719. 10.1088/0022-3719/18/17/013Golubev, V.G., Ivanov-Omskii, V.I., Minervin, I.G., Osutin, A.V., Polyakov, D.G., (1985) Sov. Phys. JETP, 61, p. 1214. , SPHJAR 0038-5646De Dios-Leyva, M., Reyes-GĂłmez, E., Perdomo-Leiva, C.A., Oliveira, L.E., (2006) Phys. Rev. B, 73, p. 085316. , PRBMDO. 0163-1829. 10.1103/PhysRevB.73.085316Li, E.H., (2000) Physica e (Amsterdam), 5, p. 215. , PELNFM 1386-9477 10.1016/S1386-9477(99)00262-3Dresselhaus, G., (1955) Phys. Rev., 100, p. 580. , PHRVAO 0031-899X 10.1103/PhysRev.100.58
Preference incorporation in MOEA/D using an outranking approach with imprecise model parameters
Multi-objective Optimization Evolutionary Algorithms (MOEAs) face numerous challenges when they are used to solve Many-objective Optimization Problems (MaOPs). Decomposition-based strategies, such as MOEA/D, divide an MaOP into multiple single-optimization sub-problems, achieving better diversity and a better approximation of the Pareto front, and dealing with some of the challenges of MaOPs. However, these approaches still require one to solve a multi-criteria selection problem that will allow a Decision-Maker (DM) to choose the final solution. Incorporating preferences may provide results that are closer to the region of interest of a DM. Most of the proposals to integrate preferences in decomposition-based MOEAs prefer progressive articulation over the âa prioriâ incorporation of preferences. Progressive articulation methods can hardly work without comparable and transitive preferences, and they can significantly increase the cognitive effort required of a DM. On the other hand, the âa prioriâ strategies do not demand transitive judgements from the DM but require a direct parameter elicitation that usually is subject to imprecision. Outranking approaches have properties that allow them to suitably handle non-transitive preferences, veto conditions, and incomparability, which are typical characteristics of many real DMs. This paper explores how to incorporate DM preferences into MOEA/D using the âa prioriâ incorporation of preferences, based on interval outranking relations, to handle imprecision when preference parameters are elicited. Several experiments make it possible to analyze the proposal's performance on benchmark problems and to compare the results with the classic MOEA/D without preference incorporation and with a recent, state-of-the-art preference-based decomposition algorithm. In many instances, our results are closer to the Region of Interest, particularly when the number of objectives increases
Nuclear Parton Distributions - a DGLAP Analysis
Nuclear parton distributions are studied within a framework of
the DGLAP evolution. Measurements of in deep inelastic
collisions, and Drell--Yan dilepton cross sections measured in collisions
are used as constraints. Also conservation of momentum and baryon number is
required. It is shown that the calculated evolution of agrees very well with the recent NMC data, and that the ratios
are only moderately sensitive to the choice of a specific modern
set of free parton distributions. For general use, we offer a numerical
parametrization of for all parton flavours in , and at
and .Comment: Talk in Quark Matter '99, 5 pages, includes 3 eps-figure
An ACO-based Hyper-heuristic for Sequencing Many-objective Evolutionary Algorithms that Consider Different Ways to Incorporate the DM's Preferences
Many-objective optimization is an area of interest common to researchers, professionals, and practitioners because of its real-world implications. Preference incorporation into Multi-Objective Evolutionary Algorithms (MOEAs) is one of the current approaches to treat Many-Objective Optimization Problems (MaOPs). Some recent studies have focused on the advantages of embedding preference models based on interval outranking into MOEAs; several models have been proposed to achieve it. Since there are many factors influencing the choice of the best outranking model, there is no clear notion of which is the best model to incorporate the preferences of the decision maker into a particular problem. This paper proposes a hyper-heuristic algorithmânamed HyperACOâthat searches for the best combination of several interval outranking models embedded into MOEAs to solve MaOPs. HyperACO is able not only to select the most appropriate model but also to combine the already existing models to solve a specific MaOP correctly. The results obtained on the DTLZ and WFG test suites corroborate that HyperACO can hybridize MOEAs with a combined preference model that is suitable to the problem being solved. Performance comparisons with other state-of-the-art MOEAs and tests for statistical significance validate this conclusion
Patient reported outcome measure in atopic dermatitis patients treated with dupilumab: 52-weeks results
Dupilumab is used to treat atopic dermatitis (AD) patients who have proven to be refractory to previous treatments. The aim of this study was to assess evolution and patient reported outcome measures in adult patients with moderate-to-severe AD treated with dupilumab in routine clinical practice. The outcomes were evaluated and registered at baseline and weeks 16, 40 and 52. The variables evaluated were: disease severity, pruritus, stressful life events, difficulty to sleep, anxiety and depression, quality of life, satisfaction, adherence to the treatment, efficacy and safety. Eleven patients were recruited between 14 Nov 2017 and 16 Jan 2018. Demographic variables: 90% Caucasian, 82% women. Clinical variables: Mean duration of AD = 17.7 (±12.8), 91% had severe disease severity. At baseline, SCORAD median (range) score = 69.2 (34.8â89.2); itch was reported by 100% of patients; itch visual analogue scale median (range) was 9 (6â10); HADS median (range) total score = 13 (5â21); DLQI mean score = 16 (2â27); EQ-5D-3L median (range) = 57 (30â99). At week- 52 there was a significant reduction of SCORAD scores median (range) = 4.3 (0â17.1), HADS total score median (range) = 2 (0â10) and improved quality of life EQ-5D-3L median (range) = 89 (92â60). This study confirms that dupilumab, used for 52-weeks under routine clinical practice, maintains the improved atopic dermatitis signs and symptoms obtained at week 16, with a good safety profile. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
Application of mineralogical, petrological and geochemical tools for evaluating the palaeohdrogeological evolution of the PADAMOT study sites
The role of Work Package (WP) 2 of the PADAMOT project â âPalaeohydrogeological Data
Measurementsâ - has been to study late-stage fracture mineral and water samples from
groundwater systems in Spain, Sweden, United Kingdom and the Czech Republic, with the aim
of understanding the recent palaeohydrogeological evolution of these groundwater systems. In
particular, the project sought to develop and evaluate methods for obtaining information about
past groundwater evolution during the Quaternary (about the last 2 million years) by examining
how the late-stage mineralization might record mineralogical, petrographical and geochemical
evidence of how the groundwater system may have responded to past geological and
climatological changes.
Fracture-flow groundwater systems at six European sites were studied:
âą Melechov Hill, in the Bohemian Massif of the Czech Republic: a shallow (0-100 m)
dilute groundwater flow system within the near-surface weathering zone in fractured
granitic rocks;
âą Cloud Hill, in the English Midlands: a (~100 m) shallow dilute groundwater flow system
in fractured and dolomitized Carboniferous limestone;
âą Los Ratones, in southwest Spain: an intermediate depth (0-500 m) dilute groundwater
flow system in fractured granitic rocks;
âą Laxemar, in southeast Sweden: a deep (0-1000 m) groundwater flow system in fractured
granitic rocks. This is a complex groundwater system with potential recharge and
flushing by glacial, marine, lacustrine and freshwater during the Quaternary;
âą Sellafield, northwest England: a deep (0-2000 m) groundwater flow system in fractured
Ordovician low-grade metamorphosed volcaniclastic rocks and discontinuous
Carboniferous Limestone, overlain by a Permo-Triassic sedimentary sequence with
fracture and matrix porosity. This is a complex coastal groundwater system with deep
hypersaline sedimentary basinal brines, and deep saline groundwaters in crystalline
basement rocks, overlain by a shallow freshwater aquifer system. The site was glaciated
several times during the Quaternary and may have been affected by recharge from glacial
meltwater;
âą Dounreay, northeast Scotland: a deep (0-1400 m) groundwater flow system in fractured
Precambrian crystalline basement overlain by fractured Devonian sedimentary rocks.
This is within the coastal discharge area of a complex groundwater system, comprising
deep saline groundwater hosted in crystalline basement, overlain by a fracture-controlled
freshwater sedimentary aquifer system. Like Sellafield, this area experienced glaciation
and may potentially record the impact of glacial meltwater recharge.
In addition, a study has been made of two Quaternary sedimentary sequences in Andalusia in
southeastern Spain to provide a basis of estimating the palaeoclimatic history of the region that
could be used in any reconstruction of the palaeoclimatic history at the Los Ratones site:
âą The CĂșllar-Baza lacustrine sequence records information about precipitation and
palaeotemperature regimes, derived largely from the analysis of the stable isotope (ÎŽ18O
and ÎŽ13C) signatures from biogenic calcite (ostracod shells).
âą The Padul Peat Bog sequence provided information on past vegetation cover and
palaeogroundwater inputs based on the study of fossil pollen and biomarkers as proxies
for past climate change.
Following on from the earlier EC 4th Framework EQUIP project, the focus of the PADAMOT
studies has been on calcite mineralization. Calcite has been identified as a late stage mineral, closely associated with hydraulically-conductive fractures in the present-day groundwater
systems at the Ăspö-Laxemar, Sellafield, Dounreay and Cloud Hill sites. At Los Ratones and
Melechov sites late-stage mineralization is either absent or extremely scarce, and both the
quantity and fine crystal size of any late-stage fracture mineralization relevant to Quaternary
palaeohydrogeological investigations is difficult to work with. The results from the material
investigated during the PADAMOT studies indicate that the fracture fillings at these sites are
related to hydrothermal activity, and so do not have direct relevance as Quaternary indicators.
Neoformed calcite has not been found at these two sites at the present depth of the investigations.
Furthermore, the HCO3
- concentration in all the Los Ratones groundwaters is mainly controlled
by complex carbonate dissolution. The carbonate mineral saturation indices do not indicate
precipitation conditions, and this is consistent with the fact that neoformed calcite, ankerite or
dolomite have not been observed petrographically
Deep Inelastic Scattering in Holographic AdS/QCD Models
We review the description of deep inelastic scattering using some AdS/QCD
phenomenological models.Comment: Talk presented by NRFB at Light Cone 2009: Relativistic Hadronic and
Particle Physics, 8-13 Jul 2009, Sao Jose dos Campos, Brazi
Nuclear parton distributions at next to leading order
We perform a next to leading order QCD global analysis of nuclear deep
inelastic scattering and Drell-Yan data using the convolution approach to
parameterize nuclear parton densities. We find both a significant improvement
in the agreement with data compared to previous extractions, and substantial
differences in the scale dependence of nuclear effects compared to leading
order analyses.Comment: 9 pages, 10 figure
Electromagnetic vertex function of the pion at T > 0
The matrix element of the electromagnetic current between pion states is
calculated in quenched lattice QCD at a temperature of . The
nonperturbatively improved Sheikholeslami-Wohlert action is used together with
the corresponding improved vector current. The electromagnetic
vertex function is extracted for pion masses down to and
momentum transfers .Comment: 17 pages, 8 figure
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