Sample records for zwieten csaba farsang
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., Howard P. Hanson, Lynn Rauchenstein, James Van Zwieten, Desikan Bharathan, Donna Heimiller, Nicholas Langle, George N. Scott, James Potemra, N. John Nagurny, and Eugene Jansen. 2012. Ocean Thermal
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Jain, Jainendra
2011-07-15
The fractional quantum Hall effect (FQHE) is one of the most amazing collective states discovered in modern times. A remarkably detailed and accurate understanding of its nonperturbative physics has been achieved in terms of a new class of exotic particles called composite fermions. I will begin with a brief review of the composite fermion theory and its outstanding successes. The rest of the talk will be concerned with fractional quantum Hall effect in graphene, observed recently. I will present results of theoretical studies that demonstrate that composite fermions are formed in graphene as well, but the spin and valley degeneraciesmore » and the linear dispersion of electrons produce interesting new physics relative to that in the usual two-dimensional GaAs systems. Composite fermion theory allows detailed predictions about FQHE in graphene in regimes when either or both of the spin and valley degeneracies are broken. I will discuss the relevance of our theory to recent experiments. This work on FQHE in graphene has been performed in collaboration with Csaba Toke.« less
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36th International Conference on High Energy Physics
NASA Astrophysics Data System (ADS)
The Australian particle physics community was honoured to host the 36th ICHEP conference in 2012 in Melbourne. This conference has long been the reference event for our international community. The announcement of the discovery of the Higgs boson at the LHC was a major highlight, with huge international press coverage. ICHEP2012 was described by CERN Director-General, Professor Rolf Heuer, as a landmark conference for our field. In additional to the Higgs announcement, important results from neutrino physics, from flavour physics, and from physics beyond the standard model also provided great interest. There were also updates on key accelerator developments such as the new B-factories, plans for the LHC upgrade, neutrino facilities and associated detector developments. ICHEP2012 exceeded the promise expected of the key conference for our field, and really did provide a reference point for the future. Many thanks to the contribution reviewers: Andy Bakich, Csaba Balazs, Nicole Bell, Catherine Buchanan, Will Crump, Cameron Cuthbert, Ben Farmer, Sudhir Gupta, Elliot Hutchison, Paul Jackson, Geng-Yuan Jeng, Archil Kobakhidze, Doyoun Kim, Tong Li, Antonio Limosani (Head Editor), Kristian McDonald, Nikhul Patel, Aldo Saavedra, Mark Scarcella, Geoff Taylor, Ian Watson, Graham White, Tony Williams and Bruce Yabsley.
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Hindumathi, V; Kranthi, T; Rao, S B; Manimaran, P
2014-06-01
With rapidly changing technology, prediction of candidate genes has become an indispensable task in recent years mainly in the field of biological research. The empirical methods for candidate gene prioritization that succors to explore the potential pathway between genetic determinants and complex diseases are highly cumbersome and labor intensive. In such a scenario predicting potential targets for a disease state through in silico approaches are of researcher's interest. The prodigious availability of protein interaction data coupled with gene annotation renders an ease in the accurate determination of disease specific candidate genes. In our work we have prioritized the cervix related cancer candidate genes by employing Csaba Ortutay and his co-workers approach of identifying the candidate genes through graph theoretical centrality measures and gene ontology. With the advantage of the human protein interaction data, cervical cancer gene sets and the ontological terms, we were able to predict 15 novel candidates for cervical carcinogenesis. The disease relevance of the anticipated candidate genes was corroborated through a literature survey. Also the presence of the drugs for these candidates was detected through Therapeutic Target Database (TTD) and DrugMap Central (DMC) which affirms that they may be endowed as potential drug targets for cervical cancer.
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Space Launch System Implementation of Adaptive Augmenting Control
NASA Technical Reports Server (NTRS)
VanZwieten, Tannen S.; Wall, John H.; Orr, Jeb S.
2014-01-01
Given the complex structural dynamics, challenging ascent performance requirements, and rigorous flight certification constraints owing to its manned capability, the NASA Space Launch System (SLS) launch vehicle requires a proven thrust vector control algorithm design with highly optimized parameters to robustly demonstrate stable and high performance flight. On its development path to preliminary design review (PDR), the stability of the SLS flight control system has been challenged by significant vehicle flexibility, aerodynamics, and sloshing propellant dynamics. While the design has been able to meet all robust stability criteria, it has done so with little excess margin. Through significant development work, an adaptive augmenting control (AAC) algorithm previously presented by Orr and VanZwieten, has been shown to extend the envelope of failures and flight anomalies for which the SLS control system can accommodate while maintaining a direct link to flight control stability criteria (e.g. gain & phase margin). In this paper, the work performed to mature the AAC algorithm as a baseline component of the SLS flight control system is presented. The progress to date has brought the algorithm design to the PDR level of maturity. The algorithm has been extended to augment the SLS digital 3-axis autopilot, including existing load-relief elements, and necessary steps for integration with the production flight software prototype have been implemented. Several updates to the adaptive algorithm to increase its performance, decrease its sensitivity to expected external commands, and safeguard against limitations in the digital implementation are discussed with illustrating results. Monte Carlo simulations and selected stressing case results are shown to demonstrate the algorithm's ability to increase the robustness of the integrated SLS flight control system.
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A novel histological technique for distinguishing between epithelial cells in forensic casework.
French, Claire E V; Jensen, Cynthia G; Vintiner, Susan K; Elliot, Douglas A; McGlashan, Susan R
2008-06-10
There are a number of forensic cases in which the identification of the epithelial cell type from which DNA originated would provide important probative evidence. This study aimed to develop a technique using histological staining of fixed cells to distinguish between skin, buccal and vaginal epithelium. First, 11 different stains were screened on formalin-fixed, wax-embedded cells from five women. Samples were analysed qualitatively by examining staining patterns (colour) and morphology (absence or presence of nuclei). Three of the staining methods--Dane's, Csaba's and Ayoub-Shklar--were successful in distinguishing skin epithelial cells from buccal and vaginal. Second, cells were smeared directly onto slides, fixed with one of five fixatives and stained with one of the three stains mentioned above. Methanol fixation, coupled with the Dane's staining method, specific to keratin, was the only technique that distinguished between all three cell types. Skin cells stained magenta, red and orange and lacked nuclei; buccal cells stained predominantly orange-pink with red nuclei; while vaginal cells stained bright orange with orange nuclei and a blue extracellular hue. This staining pattern in vaginal cells was consistent in samples collected from 50 women aged between 18 and 67. Identification of cell type from unlabelled micrographs by 10 trained observers showed a mean success rate of 95%. The results of this study demonstrate that histological staining may provide forensic scientists with a technique for distinguishing between skin, buccal and vaginal epithelial cells and thus would enable more conclusive analyses when investigating sexual assault cases.
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NASA Astrophysics Data System (ADS)
Wu, Mingzhong
As an in-plane charge current flows in a heavy metal film with spin-orbit coupling, it produces a torque that can induce magnetization switching in a neighboring ferromagnetic metal film. Such spin-orbit torque (SOT)-induced switching has been studied extensively in recent years and has shown higher efficiency than switching using conventional spin-transfer torque. This presentation reports the SOT-assisted switching in heavy metal/magnetic insulator systems.1 The experiments made use of Pt/BaFe12O19 bi-layered structures. Thanks to its strong spin-orbit coupling, Pt has been widely used to produce pure spin currents in previous studies. BaFe12O19 is an M-type barium hexagonal ferrite and is often referred as BaM. It is one of the few magnetic insulators with strong magneto-crystalline anisotropy and shows an effective uniaxial anisotropy field of about 17 kOe. It's found that the switching response in the BaM film strongly depends on the charge current applied to the Pt film. When a constant magnetic field is applied in the film plane, the charge current in the Pt film can switch the normal component of the magnetization (M⊥) in the BaM film between the up and down states. The current also dictates the up and down states of the remnant magnetization when the in-plane field is reduced to zero. When M⊥ is measured by sweeping an in-plane field, the response manifests itself as a hysteresis loop, which evolves in a completely opposite manner if the sign of the charge current is flipped. When the coercivity is measured by sweeping an out-of-plane field, its value can be reduced or increased by as much as about 500 Oe if an appropriate charge current is applied. 1. P. Li, T. Liu, H. Chang, A. Kalitsov, W. Zhang, G. Csaba, W. Li, D. Richardson, A. Demann, G. Rimal, H. Dey, J. S. Jiang, W. Porod, S. Field, J. Tang, M. C. Marconi, A. Hoffmann, O. Mryasov, and M. Wu, Nature Commun. 7:12688 doi: 10.1038/ncomms12688 (2016).
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NASA Astrophysics Data System (ADS)
Salehi-Fashami, M.; Al-Rashid, M.; Sun, Wei-Yang; Nordeen, P.; Bandyopadhyay, S.; Chavez, A. C.; Carman, G. P.; Atulasimha, J.
2016-10-01
Nanomagnetic logic has emerged as a potential replacement for traditional Complementary Metal Oxide Semiconductor (CMOS) based logic because of superior energy-efficiency (Salahuddin and Datta 2007 Appl. Phys. Lett. 90 093503, Cowburn and Welland 2000 Science 287 1466-68). One implementation of nanomagnetic logic employs shape-anisotropic (e.g. elliptical) ferromagnets (with two stable magnetization orientations) as binary switches that rely on dipole-dipole interaction to communicate binary information (Cowburn and Welland 2000 Science 287 1466-8, Csaba et al 2002 IEEE Trans. Nanotechnol. 1 209-13, Carlton et al 2008 Nano Lett. 8 4173-8, Atulasimha and Bandyopadhyay 2010 Appl. Phys. Lett. 97 173105, Roy et al 2011 Appl. Phys. Lett. 99 063108, Fashami et al 2011 Nanotechnology 22 155201, Tiercelin et al 2011 Appl. Phys. Lett. 99 , Alam et al 2010 IEEE Trans. Nanotechnol. 9 348-51 and Bhowmik et al 2013 Nat. Nanotechnol. 9 59-63). Normally, circular nanomagnets are incompatible with this approach since they lack distinct stable in-plane magnetization orientations to encode bits. However, circular magnetoelastic nanomagnets can be made bi-stable with a voltage induced anisotropic strain, which provides two significant advantages for nanomagnetic logic applications. First, the shape-anisotropy energy barrier is eliminated which reduces the amount of energy required to reorient the magnetization. Second, the in-plane size can be reduced (˜20 nm) which was previously not possible due to thermal stability issues. In circular magnetoelastic nanomagnets, a voltage induced strain stabilizes the magnetization even at this size overcoming the thermal stability issue. In this paper, we analytically demonstrate the feasibility of a binary ‘logic wire’ implemented with an array of circular nanomagnets that are clocked with voltage-induced strain applied by an underlying piezoelectric substrate. This leads to an energy-efficient logic paradigm orders of magnitude superior to existing CMOS-based logic that is scalable to dimensions substantially smaller than those for existing nanomagnetic logic approaches. The analytical approach is validated with experimental measurements conducted on dipole coupled Nickel (Ni) nanodots fabricated on a PMN-PT (Lead Magnesium Niobate-Lead Titanate) sample.
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Image-based modeling of flow and reactive transport in porous media
NASA Astrophysics Data System (ADS)
Qin, Chao-Zhong; Hoang, Tuong; Verhoosel, Clemens V.; Harald van Brummelen, E.; Wijshoff, Herman M. A.
2017-04-01
Due to the availability of powerful computational resources and high-resolution acquisition of material structures, image-based modeling has become an important tool in studying pore-scale flow and transport processes in porous media [Scheibe et al., 2015]. It is also playing an important role in the upscaling study for developing macroscale porous media models. Usually, the pore structure of a porous medium is directly discretized by the voxels obtained from visualization techniques (e.g. micro CT scanning), which can avoid the complex generation of computational mesh. However, this discretization may considerably overestimate the interfacial areas between solid walls and pore spaces. As a result, it could impact the numerical predictions of reactive transport and immiscible two-phase flow. In this work, two types of image-based models are used to study single-phase flow and reactive transport in a porous medium of sintered glass beads. One model is from a well-established voxel-based simulation tool. The other is based on the mixed isogeometric finite cell method [Hoang et al., 2016], which has been implemented in the open source Nutils (http://www.nutils.org). The finite cell method can be used in combination with isogeometric analysis to enable the higher-order discretization of problems on complex volumetric domains. A particularly interesting application of this immersed simulation technique is image-based analysis, where the geometry is smoothly approximated by segmentation of a B-spline level set approximation of scan data [Verhoosel et al., 2015]. Through a number of case studies by the two models, we will show the advantages and disadvantages of each model in modeling single-phase flow and reactive transport in porous media. Particularly, we will highlight the importance of preserving high-resolution interfaces between solid walls and pore spaces in image-based modeling of porous media. References Hoang, T., C. V. Verhoosel, F. Auricchio, E. H. van Brummelen, and A. Reali (2016), Mixed Isogeometric Finite Cell Methods for the Stokes problem, Computer Methods in Applied Mechanics and Engineering, doi:10.1016/j.cma.2016.07.027. Scheibe, T. D., W. A. Perkins, M. C. Richmond, M. I. McKinley, P. D. J. Romero-Gomez, M. Oostrom, T. W. Wietsma, J. A. Serkowski, and J. M. Zachara (2015), Pore-scale and multiscale numerical simulation of flow and transport in a laboratory-scale column, Water Resources Research, 51(2), 1023-1035, doi:10.1002/2014WR015959. Verhoosel, C. V., G. J. van Zwieten, B. van Rietbergen, and R. de Borst (2015), Image-based goal-oriented adaptive isogeometric analysis with application to the micro-mechanical modeling of trabecular bone, Computer Methods in Applied Mechanics and Engineering, 284(February), 138-164, doi:10.1016/j.cma.2014.07.009.
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The history of the Laboratory of Pathology of the Cluj-Napoca Oncological Institute.
Simu, G; Buiga, R
2006-01-01
The Laboratory of Pathology of the actual "Professor Ion Chiricută" Oncological Institute of Cluj-Napoca, former "Iuliu Maniu" Institute for Cancer Study and Prophylaxis, had the privilege that in its framework carry on an important part of their activity professors Titu Vasiliu and Rubin Popa, who are forming, beside Victor Babeş, the golden trinity of the Romanian pathology. The Cancer Institute of Cluj, one of the first in the World, was founded in 1929, especially by the clear-sightedness and the efforts of Professor Iuliu Moldovan, the master of the modern Romanian school of hygiene. The clinic division was assisted by a Laboratory of Pathology, whose chief was appointed the young pathologist of high competence, Rubin Popa, associate Professor of this department of the Cluj School of Medicine. In 1942' he became director of the Institute, function accomplished until his premature disappearance in 1958. Titu Vasiliu worked in the Oncological Institute from 1949, a year after his forced retreat from the chair of pathology, up to 1958. Fortunately, his premature disappearance did not interrupt the activity of the laboratory, because the management of the Oncological Institute was committed to Ion Chiricută, an experimented and modern surgeon of Bucharest. From 1960, the Laboratory of Pathology has been led by Professor Augustin Mureşan, an experimented, rigorous and prudent pathologist, who has imprinted these indispensable qualities to his disciples learning under his leadership. The activity of the laboratory has been very favorably influenced by the presence of Professor Gheorghe Badenski from the Department of Microbiology. The collaboration with Professor Eugen Pora from Babeş-Bolyai Department of Animal Physiology and his disciples, Virgil Toma, Draga Nestor, Sena Roşculet, Carmen Stugren and Georgette Buga has carried on the performance of interesting works concerning the thymus involution in tumor-bearing hosts and its signification for the depressed immunity in the advanced stages of cancer. In the same direction, the behavior of mast cells has been studied in collaboration with Professor George Csaba from the Budapest Medical University, Department of Biology. The observations brought about were remarked by the Canadian scientist Hans Selye. Most of these works have been included in the book "Immunity and cancer", distinguished with "Victor Babeş" Prize of the Romanian Academy. The arrival in the Institute of Professor Ion Macavei, disciple of Iuliu Hatieganu and founder of the Clinical Hematology in Cluj, expert in blood and bone marrow cytology, has given a strong impulse to the studies of malignant hemopoietic diseases. The current use of cytologic and histopathologic examinations in this field of pathology and, especially, the introduction by him, for the first time in Romania, of the osteomedullary biopsy has permitted the elaboration of an appreciated work about the cytologic and histologic diagnosis of lymphadenopathies. In the histochemical-histoenzymatic period of the microscopic diagnosis, between the years 1960-1990, the laboratory has enjoyed by the advices and the material help of Professor Raymond Wegmann from the Paris University, Institute of Histochemistry, the founder-editor of the International Review of Histochemistry, from 1976, of Cellular and Molecular Biology, who visited our laboratory in 1992. From 1965, in an adjacent Laboratory of Cytogenetics, Corneliu D. Olinici has performed the first karyotypes in Cluj and has teached the method to several other specialists. Despite the technical difficulties, the works performed in the Laboratory of Pathology have succeeded sometimes to reach the quality required by Professor Chiricută to a valuable scientific work in cancerology. This performance has been obtained by a study concerning Crabtree effect variations in tumoral metastases or about lactic-dehydrogenase behavior in breast carcinomas.
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NASA Astrophysics Data System (ADS)
2011-08-01
Abigail Alvarez OlarteCINVESTAV Alba Leticia Carrillo MonteverdeDCI-UG Alberto CarramiñanaINAOE Aldo MorselliFERMI Alejandro CastillaDCI-UG Alejandro IbarraTechnical University of Munich Alma D Rojas PachecoFCFM-BUAP Alma Xochitl Gonzalez MoralesInstituto de Ciencias Nucleares, UNAM Andrew Walcott BeckwithAmerican Institute of Beam Energy Physics Ariadna Montiel ArenasDepartamento de Física, CINVESTAV Arnulfo ZepedaCinvestav Arturo Alvarez CruzInstituto de Fisica, UNAM Axel de la MacorraUNAM, IAC Azar MustafayevUniversity of Minnesota Benjamin JaramilloDCI-UG Vincent BertinCPPM-Marseille Carlos Alberto Vaquera-AraujoDCI-UG Carlos MuñozMadrid Autonoma U. & Madrid, IFT Carmine PagliaroneINFN, FNAL Carolina Lujan PeschardDCI-UG Christiane Frigerio MartinsUniversidade Federal do ABC-São Paulo Csaba BalazsMonash University David DelepineDCI-UG David G CerdenoUniversidad Autonoma de Madrid & Instituto de Fisica Teorica Debasish MajumdarSaha Institute of Nuclear Physics, Kolkata, India Dibyendu PanigrahiKandi Raj College, Kandi, Murshidabad, INDIA-742137 Dupret Alberto Santana BejaranoUniversidad de Sonora Departamento de Investigacion en Fisica Ernest MaRiverside U.C. Esteban Alejandro Reyes Pírez MontañezInstituto de Física, UNAM Federico Ortiz TrejoINSTITUTO DE ASTRONOMÍA - UNAM Francisco José de Anda NavarroUniversidad de Guadalajara González Alvarez Francisco JavierCINVESTAV-Depto. Física Gustavo Medina TancoICN-UNAM Hernando Efrain Caicedo OrtizInstituto Politecnico Nacional - IPN J D VergadosCERN & Ioannina U. James R BoyceJefferson Lab Jason SteffenFERMILAB Javier Montaño DomínguezDCI-UG Jeevan SolankiMandsaur Institue of Technology MP India Joe SatoSaitama University Jorge Luis Navarro EstradaUNAM-ICN and Universidad del Atlantico (B/quilla-Col.) Jose A R CembranosUniversity of Minnesota José DíazIFIC Jose Didino Garcia AguilarDepto. de Fisica. Cinvestav Keith OliveUniversity of Minnesota Konstantia BalasiUniversity of Ioannina, Greece Lilian Prado GonzalezBUAP, FCFM Lorenzo Díaz CruzBUAP Facultad de Ciencias Físico Matemáticas Luis Rey Díaz BarrónDivisión de Ciencias e Ingenierías Luis UrenaUniversidad de Guanajuato Magda LolaDept. of Physics, University of Patras, Greece Mahmoud WahbaEgyptian Center for Theoretical Physics, MTI Marcus S CohenNew Mexico State University Mario A Acero OrtegaICN - UNAM Mario E GomezUniversidad de Huelva Mark PipeUniversity of Sheffield Mauro NapsucialeDCI-UG Mirco CannoniUniversidad de Huelva Mónica Felipa Ramírez PalaciosUniversidad de Guadalajara Murli Manohar VermaLucknow university, India Nassim BozorgniaUCLA Octavio Obregón Octavio ValenzuelaIA-UNAM Oleg KamaevUniversity of Minnesota Osamu SetoHokkai-Gakuen University Pedro F González DíazIFF, CSIC, Serrano 121, 28006 Madrid, Spain Qaisar ShafiBartol Research Inst. and Delaware U. Raul Hennings-YeomansLos Alamos National Laboratory René Ángeles MartínezDepartamento de Fisica, del DCI de la Universidad de Guanajuato Reyna XoxocotziBUAP, FCFM Rishi Kumar TiwariGovt. Model Science College, Rewa (MP) INDIA Roberto A SussmanICN-UNAM Selim Gómez ÁvilaDCI-UG Sugai KenichiSaitama University Susana Valdez AlvaradoDCI-UG TVladimir - 2K CollaborationColorado State University Tonatiuh MatosCINVESTAV Valeriy DvoeglazovUniversidad de Zacatecas Vannia Gonzalez MaciasDCI-UG Vladimir Avila-ReeseInstituto de Astronomia, UNAM Wolfgang BietenholzINC, UNAM (Mexico) Yamanaka MasatoKyoto Sangyo University Yann MambriniLPT Orsay Yu-Feng ZhouInstitute of Theotretical Physics, Chinese Academy of Sciences, PR China Aaron HigueraDCI-UG Azarael Yebra PérezDCI-UG César Hernández AguayoDCI-UG Jaime Chagoya AlvarezDCI-UG Jonathan Rashid Rosique CampuzanoDCI-UG José Alfredo Soto ÁlvarezDCI-UG Juan Carlos De Haro SantosDCI-UG Luis Eduardo Medina MedranoDCI-UG Maria Fatima Rubio EspinozaDCI-UG Paulo Alberto Rodriguez HerreraDCI-UG Roberto Oziel Gutierrez CotaDCI-UG Rocha Moran Maria PaulinaDCI-UG Xareni Sanchez MonroyDCI-UG
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NASA Astrophysics Data System (ADS)
Horvath, E.; Jordan, G.; Fugedi, U.; Bartha, A.; Kuti, L.; Heltai, G.; Kalmar, J.; Waldmann, I.; Napradean, I.; Damian, G.
2009-04-01
INTRODUCTION Wide-spread environmental contamination associated with historic mining in Europe has triggered social responses to improve related environmental legislation, the environmental assessment and management methods for the mining industry. Pollution by acid mine drainage (AMD) from ore and coal mining is the outstanding and most important source of mining-induced environmental pollution. Younger et al. (2002) estimates that watercourses polluted by coal mine drainage could be in the order of 2,000 to 3,000 km, and 1,000 to 1,500 km polluted by metal mine discharges for the EU 15 Member States (Younger et al. 2002). Significance of contamination risk posed by mining is also highlighted by mine accidents such as those in Baia Mare, Romania in 2002 and in Aznalcollar, Spain in 1999 (Jordan and D'Alessandro 2004). The new EU Mine Waste Directive (Directive 2006/21/EC) requires the risk-based inventory of abandoned mines in the EU. The cost-effective implementation of the inventory is especially demanding in countries with extensive historic mining and great number of abandoned mine sites, like Romania. The problem is further complicated in areas with trans-boundary effects. The objective of this investigation to carry out the risk-based contamination assessment of a mine site with possible trans-boundary effects in Romania. Assessment follows the source-pathway-receptor chain with a special attention to heavy metal leaching from waste dumps as sources and to transport modelling along surface water pathways. STUDY AREA In this paper the Baiut mine catchment located in the Gutai Mts., Romania, close to the Hungarian border is studied. The polymetallic deposites in the Tertiary Inner-Carpathian Volcanic Arc are exposed by a series of abandoned Zn and Pb mines first operated in the 14th century. Elevation in the high relief catchment ranges from 449m to 1044m. Geology is characterised by andesites hosting the ore deposits and paleogene sediments dominating at the lower topographic elevations. Several mine adits, waste rock dumps are located along the main stream and a large tailings dump is found next to village Baiut just above the receiving floodplain. Predominant land cover is coniferous and mixed forests with agricultural lands on the downstream floodplain. METHODS Six samples at vaious depths were collected from the two major waste rock dumps in the headwater area, and the large tailings dump was also sampled for heavy metal source characterisation. 11 stream sediment samples were collected along the main surface water contamination transport pathway, and a further 11 soil samples were collected in 2 boreholes in the receptor floodplain in October 2008. Besides background stream sediment samples, samples from the exposed rock formations were also collected in order to capture natural background geochemistry in the studied mineralised area. The collected waste rock, stream sediment, soil and rock samples are analysed for total chemical composition (major elements and heavy metals) by ICP-MS spectroscopy, and XRD is used for the determination of mineralogical composition. Rock sample mineralogy is further investigated in thin-sections by petrological microscopy. According to EU legislation expectations, a special emphasis is taken on the determination of metal mobility from the waste rock dumps and various leaching tests are performed and compared including US EPA, USGS and ISO methods. A simple cathcment-based distributed sediment transport model (Jordan et al, 2005; Jordan et al. 2005, 2008) is used to decribe the pathways and quantities of particle-bound contamination. RESULTS AND CONCLUSIONS Results show that (1) sediments are an efficient means for the preliminary inventory of mine contamination as a preparation for the more detailed hydrological sampling and assessment, and (2) the risk-based contamination assessment of mining sites often located in diverse geological, hydrological and landcover environment requires careful and successive sampling design and a tiered assessment approach. Leaching tests are shown cost-efficient and informative methods for source (hazard) characterisation. REFERENCES Directive 2006/21/EC the European Parliament and of the Council on the management of waste from extractive industries and amending Directive 2004/35/EC. Commission of the European Communities, Brussels. Jordan G. and D'Alessandro M. (eds) (2004) Mining, Mining Waste and Related Environmental Issues: Problems and Solutions in the Central and Eastern European Candidate Countries. Joint Research Centre of the European Commission, Ispra. LB-NA-20868-EN-C. Jordan G., van Rompaey A., Szilassi P., Csillag G., Mannaerts C. and Woldai T. (2005) Historical land use changes and their impact on sediment fluxes in the Balaton basin (Hungary). Agriculture, Ecosystems and Environment, 108, 119-133. Jordan G., van Rompaey A., Somody A., Fügedi U., Bats M. and Farsang A. (2008) Spatial Modelling of Contamination in a Catchment Area Impacted by Mining: a Case Study for the Recsk Copper Mines, Hungary. Journal of Land Contamination and Reclamation (in press). Younger P.L., Banwart S.A., Hedin R.S. (2002) Mine water. Hydrology, pollution, remediation. Kluwer Academic Publishers, Dodrecht.
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NASA Astrophysics Data System (ADS)
Demming, Anna
2012-09-01
Putting theory into practice in nanotechnology can be far from trivial. Magnetic artificial atoms have been an example of the gulf that can sometimes separate idea from experiment. The step from regular semiconductor artificial atoms to magnetic may not confound the imagination, but it poses no mean fabrication challenge to experimental physicists. In this issue researchers in Germany have successfully fabricated a magnetic artificial atom [1]. As the researchers point out, the systems look promising for further study of the transport properties of 0D magnetic objects. Magnetic behavior in nanoscale systems has inspired a number of technological developments, such as energetically efficient digital logic circuitry [2]. Theory dictates that less energy is dissipated in the manipulation of nanomagnet logic bits than in the manipulation of electrical charges in transistor switches. Among the challenges when putting this into practice is the issue of sequential clocking. The nanomagnets' polarizations need to be rotated through 90° from the easy to the hard axis ready to be set before propagating the logic bits from one stage to the next. Ideally this would be a localized process to allow the efficiencies of a pipe-line computer architecture. Researchers at Virginia Commonwealth University in the US showed that a small voltage applied to a multiferroic nanomagnet can cause this polarization rotation [3]. They further showed that the switching delay of this process is not impracticably long, suggesting that the process is promising for logic circuits that are very fast as well as energy efficient [4]. Researchers in Germany have demonstrated magnetic force microscopy for high resolution imaging using a carbon nanotube filled with iron [5]. A magnetic dipole moment in the iron extends from end to end of the iron nanowire in the carbon nanotube. As a result of the extreme aspect ratio of the nanowire only the pole at one end is involved in the imaging process. The authors describe the system in terms of a magnetic monopole—a notorious theoretical element yet to make the transition to experimental observations. Yet the description works well and as the authors claim, 'The magnetic resolution comes remarkably close to the maximum reported value and can still be improved by choosing iron-filled carbon nanotubes with optimized dimensions'. Artificial atoms, or superatoms, were used in the 1970s as theoretical constructs to investigate molecular structures [6]. Later studies of fullerenes [7, 8] and then other semiconductor artificial atom systems [9] rooted the concept firmly in experimental physics. The electronic behavior in these systems has inspired some fascinating technological developments [10]. Artificial atom quantum dots are small enough to be considered zero-dimensional, giving rise to quantum confinement effects: electrons added to quantum dots occupy discrete quantum levels, and spin-paired electrons can produce spin-zero electron states. The systems have demonstrated great promise for potential qubits for quantum computers. Silicon has a number of advantages for these applications including scalability and long spin coherence times. However, progress has been hindered in practice by difficulties in creating devices with sufficiently low disorder particularly at the Si/SiO2 interface. Researchers at the University of New South Wales in Australia have overcome these fabrication challenges and demonstrated a low-disorder silicon metal-oxide-semiconductor quantum dot where the number of electrons can be tuned between 0 and 27 [11]. In this issue R-G Dengel, A Frey, K Brunner, C Gould and L W Molenkamp from Universität Würzburg in Germany create magnetic artificial atoms by replacing the traditionally used GaAs-based heterostructure with a ZnSe-based system where doping the quantum well with Mn gives it magnetic properties [1]. As they point out, 'From the fabrication point of view, three technical issues make this straightforward seeming idea very challenging to realize'. The interface between the III-V substrate and the ZnSe gives rise to strong polar fields. The lattice mismatch means that the heterostructure must be kept very thin raising further fabrication challenges, and finally there is also the issue of a lack of Schottky contact material for ZnSe. The authors demonstrate impressive ingenuity to develop a multi-step electron beam lithography process to produce the ZnSe dots. They also present preliminary transport data that confirm the magnetic nature of the resulting artificial atom. We are all familiar with the old adage: 'In theory there is no difference between theory and practice. But in practice there is.' While great progress in scientific research often builds on important synergies between theory and experiment, what the mind can conceive may take a great deal of cunning and skill in the laboratory to achieve. Yet as all these examples in nanotechnology fabrication research show, with each triumph in nanofabrication, progress is made to bridge the gap between theory and practice. References [1] Dengel R-G, Frey A, Brunner K, Gould C and Molenkamp L W 2012 Fabrication of magnetic artificial atoms Nanotechnology 23 395301 [2] Imre A, Csaba G, Ji L, Orlov A, Bernstein G H and Porod W 2006 Majority logic gate for magnetic quantum-dot cellular automata Science 311 205-8 [3] Atalusimha J and Bandyopadhyay S 2010 Bennett clocking of nanomagnetic logic using multiferroic single-domain nanomagnets Appl. Phys. Lett. 97 173105 [4] Fashami M S, Roy K, Atulasimha J and Bandyopadhyay S 2011 Magnetization dynamics, Bennett clocking and associated energy dissipation in multiferroic logic Nanotechnology 22 155201 [5] Wolny F, Mühl T, Weissker U, Lipert K, Schumann J, Leonhardt A and Büchner B 2010 Iron filled carbon nanotubes as novel monopole-like sensors for quantitative magnetic force microscopy Nanotechnology 21 435501 [6]Carhart R E, Smith D H, Brown H and Djerassi C 1975 Applications of artificial intelligence for chemical inference. XVII. An approach to computer-assisted elucidation of molecular structure J. Am. Chem. Soc. 97 5755-62 [7] Saito S, Oshiyama A, Miyamoto Y, Hamada N and Sawada S 1992 Electronic structure of fullerenes and fullerides: artificial atoms and their solids Nanotechnology 3 167-72 [8] Shinohara H 2000 Endohedral metallofullerenes Rep. Prog. Phys. 63 843-92 [9] Heitmann D, Kern K, Demel T, Grambow P, Ploog K and Zhang Y H 1992 Spectroscopy of quantum dots and antidots Surf. Sci. 267 245-52 [10] Andergassen S, Meen V, Schoeller H, Splettstoesser J and Wegewijs M R 2010 Charge transport through single molecules, quantum dots and quantum wires Nanotechnology 21 272001 [11] Lim W H, Yang C H, Zwanenburg F A and Dzurak A S 2011 Spin filling of valley-orbit states in a silicon quantum dot Nanotechnology 22 335704