280 research outputs found

    Exact and Asymptotic Measures of Multipartite Pure State Entanglement

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    In an effort to simplify the classification of pure entangled states of multi (m) -partite quantum systems, we study exactly and asymptotically (in n) reversible transformations among n'th tensor powers of such states (ie n copies of the state shared among the same m parties) under local quantum operations and classical communication (LOCC). With regard to exact transformations, we show that two states whose 1-party entropies agree are either locally-unitarily (LU) equivalent or else LOCC-incomparable. In particular we show that two tripartite Greenberger-Horne-Zeilinger (GHZ) states are LOCC-incomparable to three bipartite Einstein-Podolsky-Rosen (EPR) states symmetrically shared among the three parties. Asymptotic transformations result in a simpler classification than exact transformations. We show that m-partite pure states having an m-way Schmidt decomposition are simply parameterizable, with the partial entropy across any nontrivial partition representing the number of standard ``Cat'' states (|0^m>+|1^m>) asymptotically interconvertible to the state in question. For general m-partite states, partial entropies across different partitions need not be equal, and since partial entropies are conserved by asymptotically reversible LOCC operations, a multicomponent entanglement measure is needed, with each scalar component representing a different kind of entanglement, not asymptotically interconvertible to the other kinds. In particular the m=4 Cat state is not isentropic to, and therefore not asymptotically interconvertible to, any combination of bipartite and tripartite states shared among the four parties. Thus, although the m=4 cat state can be prepared from bipartite EPR states, the preparation process is necessarily irreversible, and remains so even asymptotically.Comment: 13 pages including 3 PostScript figures. v3 has updated references and discussion, to appear Phys. Rev.

    Anisotropic magnetoresistance of bulk carbon nanotube sheets

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    We have measured the magnetoresistance of stretched sheets of carbon nanotubes in temperatures ranging from 2 K to 300 K and in magnetic fields up to 9 T, oriented either perpendicular or parallel to the plane of the sheets. The samples have been partially aligned by post-fabrication stretching, such that the direction of stretching was either parallel or perpendicular to the direction of applied electric current. We have observed large differences between the magnetoresistance measured under the two field orientations, most pronounced at the lowest temperatures, highest fields, and for the laterally-aligned sample. Treatment of the sheets with nitric acid affects this anisotropy. We analyzed the results within the theoretical framework of weak and strong localization and concluded that the anisotropy bears the mark of a more unusual phenomenon, possibly magnetically-induced mechanical strain.Comment: 34 pages, 10 figure

    High Temperature Mixed State c−c-Axis Dissipation in Low Carrier Density Y0.54Pr0.46Ba2Cu3O7−ήY_{0.54}Pr_{0.46}Ba_{2}Cu_{3}O_{7-\delta}

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    The nature of the out-of-plane dissipation was investigated in underdoped Y0.54Pr0.46Ba2Cu3O7−ήY_{0.54}Pr_{0.46}Ba_{2}Cu_{3}O_{7-\delta} single crystals at temperatures close to the critical temperature. For this goal, temperature and angle dependent out-of-plane resistivity measurements were carried out both below and above the critical temperature. We found that the Ambegaokar-Halperin relationship [V. Ambegaokar, and B. I. Halperin, Phys. Rev. Lett. \textbf{22}, 1364 (1969)] depicts very well the angular magnetoresistivity in the investigated range of field and temperature. The main finding is that the in-plane phase fluctuations decouple the layers above the critical temperature and the charge transport is governed only by the quasiparticles. We also have calculated the interlayer Josephson critical current density, which was found to be much smaller than the one predicted by the theory of layered superconductors. This discrepancy could be a result of the d-wave symmetry of the order parameter and/or of the non BCS temperature dependence of the c-axis penetration length.Comment: Will appear in PR

    Obtaining and Characterization of Vitroceram by Chemical Doped ZnO for Art Mosaic

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    This paper presents the obtaining and the characterization of ZnO doped vitroceramic, used as photo and termoresistive pigment for art mosaic. The coprecipitation involves two sequential steps, first of ions Zn2+(aq), Cr3+(aq), Co3+(aq) and Mn3+(aq), as oxihydroxides in predetermined molar reports: 98:0,6:0,7:06, followed by maturation, forced filtration and redispersion of the granules in distilled water, after which, by ion exchange is precipitated as intergranular film of Sb3+(aq) and Bi3+(aq) ions. After forced filtration and drying, the material is subjected gradually to a thermal process, according to a curve with three levels: 20-110 °C, 110-360 °C Ɵi 360-950 °C, with a heating rate of 3 °C/min., each level keeping a constant temperature while varying between 4 and 8 h for nanostructures processes of crystalls reform. The vitroceramic was characterized by SEM-EDX, microFTIR and termic derivatography, after treatment at 110 °C and respectively 950 °C, underlining uniformity of grains and revealing their heterojonctional structure in cross-section

    From Things to Services: A Social IoT Approach for Tourist Service Management

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    In the context of Internet of Things (IoT), the cooperation and synergy between varied and disparate communicating objects is strained by trustworthiness, confidentiality and interoperability concerns. These restrictions can limit the development of IoT-based applications especially considering the emergent boost in the number of communicating objects and their growing itinerant nature in a collective service context. A new perspective arises with the paradigm of Social Internet of Things (SIoT), that relies on the implementation of semi-independent communicating objects with cooperation assessed by social relations and social feed-back. In this article, we present the development and expansion of the IoT concept towards SIoT in the context of the interactions between tourist services as communicating objects. As a proof-of-concept we propose a composition of services as virtualized social objects and the interaction between them, by taking into consideration the balance, trustworthiness, cooperation and synergy of services. Furthermore we present a solution to integrate also accessibility in SIoT services. The presented concept is presented using a demonstrator build for tourist services

    The Influence of Neutron Irradiation on (B0.65C0.35)Ba1.4Sr0.6Ca2Cu3Oz Superconducting Phase: the Role of the Grain Edge

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    Using the transport and magnetization measurements the influence of neutron irradiation at a fluence of 5x1017^{17} n cm−2^{-2} on (B0.65C0.35)Ba1.4Sr0.6Ca2Cu3Oz has been investigated. The neutron irradiation was found to decrease critical temperature and transport critical current density, increase the residual and normal state resistivity, and improve the intragranular critical current density with 1.6x1057^{57} A/cm2^{2} (at 77.3K and in the applied field up to 160 kA m) and \Delta Mirr/\Delta Mnonirr ratio (up to factor of 3) at highest field used for investigation. The field dependence of this ratio, which is below the unity at very low field but higher than 1 at high fields, correlated with the shape of the hystertic loops as well as with the change of the transport parameters after irradiation suggests the role of the irradiation induced effects on the grain edges. We discuss these effects in the framework of the Bean-Livingstone surface barriers and geometrical barriers.Comment: 12 pages, 5 figure

    The role of cardiac markers TnI, CK- MB, LDG for prediction of survival in patients with acute myocardial infarction

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    Introduction: There is an increasing morbidity of patients with acute coronary syndrome (ACS) in the structure of population mortality. The most common risk factors in ACS group , which encompasses pathology of acute myocardial infarction (AMI) is hypertension. In 2000 the European Society of Cardiology and the ACC/AHA (American College of Cardiology/American Heart Association), recognized the pivotal role of biomarkers with elevations in their levels the “cornerstone” of diagnosis of AMI. Troponina I (Tnl), Creatine kinase MB isoenzyme (CK-MB), Lactat Dedhidrogenase (LDG), Myoglobin (MYO) - these are markers of cardiac injury. Established correlation in the levels of these markers would allow the prognosis of the survival chances of patients with AMI. Aims: The goal of this study is to examine the distribution of the biomarkers of cardiac cell injury and their association with the AMI mortality rate. Materials and methods: The research was performed retrospectively, based on the archive data of the Municipal Hospital Clinic “Sf. Treime”. It has involved 17 patients with diagnosis of AMI and hypertension, like risk factor. Our patients were tested in the laboratory, data were received using comprehensive testing platform “The Alere Triage Meter Pro”, using “Alere Triage Cardiac panel” of SANMEDICO company. This is an immunoassay, for quantitative measurements of MYO (ng/ml), CK-MB (ng/ml) and Tnl (ng/ml). The marker and the main criterion of patients selection was the Tnl below the 0.05 ng/ml. Results: Patients were diagnosed with AMI, according to WHO criteria. Total number of 17 patients were examined (100%), with an average age of 57 years, 7 of them were men (41.17%) and 10 - women (58.83%). Survived during the first 24 hours after hospitalization - 7 ps (41.17%), and 10 ps (58.83%) have died. It was detected CK-MB: 58.82% above the norm (10 ps), 41.12% in normal limits (7 ps); LDG: 52.94% above the norm (9 ps), 47.06% below the norm or in normal limits (8 ps); MYO: 52.94% above the norm (9 ps). Were identified arterial hypertension level 1 and 2 in all patients, 10 of them (58,82%) were identified with anterior extended MI, that corresponds to obstruction of left anterior descending artery (LAD) artery, 3 ps (17,64%) with circular MI, that corresponds to obstruction of circumflex (CX) artery, and 4 ps (23.53%) with diaphragmatic (inferior) MI, that corresponds in most cases to obstruction of right coronary artery (RCA). From the total number of patients, we identified 9 ps (52.94%) with narrow or wide QRS tachyarrhythmia. Discussion: The main questions in our study were: 1. Increased serum levels of which markers have been associated with evidence of reversible or irreversible cardiac injury (cell lesion)? 2. What major coronary artery is frequently involved in AMI, in our region? It has been demonstrated that testing for troponins initially on admission and repeatedly after 6 or 12 hours provides better risk stratification than preciously used algorithms based on ECG, CK-MB. Elevated levels of CK-MB, LDG and MYO denote a cardiac injury. In our cases they were associated with negative troponine results, which emphasize the reversible cardiac injury. Correlated with ECG data, which determine ST elevation lead V1-V4 (52.94%), infer damage of LAD artery. Conclusion: Study data estimate implying of LAD in the coronary artery pathology (58.82% cases of extended anterior MI), in condition of functionally compromised heart (52.94% of arrhythmias). Biomarkers values ranking shows the degree of cardiac injury. At the same time they allow the prognosis of the survival chances of patients with AM

    AB and Berry phases for a quantum cloud of charge

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    We investigate the phase accumulated by a charged particle in an extended quantum state as it encircles one or more magnetic fluxons, each carrying half a flux unit. A simple, essentially topological analysis reveals an interplay between the Aharonov-Bohm phase and Berry's phase.Comment: 10 pages, TAUP 2110-93. Te

    A COMPARATIVE MULTI-TECHNIQUE INVESTIGATION ON MATERIAL IDENTIFICATION OF GILDING LAYERS AND THE CONSERVATION STATE OF 7 PORTUGUESE MANNERIST ALTARPIECES

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    This paper deals with the multi-analytical comparative characterization of 59 samples of gilded and polychrome layers from 7 altarpieces studied during the Gilt-Teller project (www.gilt-teller.pt). The altarpieces studied here belong to seven churches in the areas of Lisbon, SantarĂ©m, Portalegre and Guarda and display stylistic and constructive features characteristic to the Mannerism carved wood decoration in Portugal. The applied protocol of investigation characterized the structure and manufacture technique of gilding; identified the chemical composition of the layers constituting the gilded polychrome decoration; compared the materials and gilding techniques encountered in the 7 altarpieces and assessed the conservation state of each altarpiece. The analytical techniques applied to these purposes were: stereomicroscopy (SM), optical microscopy (OM), scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDX), X-ray diffraction (XRD), MALDI-TOF mass spectrometry, ÎŒRaman and ÎŒFTIR/imaging ÎŒFTIR spectroscopies. This interdisciplinary multi-scale approach was used to elucidate the aspects related to the material and technical aspects of “talha dourada” decoration, answering to these questions: which are the original materials and layers in the making of the polychromy and which are the ones added with posterior interventions; which are the relationships between gilding materials and techniques, regarding the degree of erudition of each case study; which were the main causes of degradation and influence to their conservation condition
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