975 resultados para Excited states
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Non-Abelian quantum Hall states are characterized by the simultaneous appearance of charge and neutral gapless edge modes, with the structure of the latter being intricately related to the existence of bulk quasiparticle excitations obeying non-Abelian statistics. Here we propose a scenario for detecting the neutral modes by having two point contacts in series separated by a distance set by the thermal equilibration length of the charge mode. We show that by using the first point contact as a heating device, the excess charge noise measured at the second point contact carries a nontrivial signature of the presence of the neutral mode. We also obtain explicit expressions for the thermal conductance and corresponding Lorentz number for transport across a quantum point contact between two edges held at different temperatures and chemical potentials.
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Pt ions-CeO2 interaction in Ce1-xPtxO2-delta (x=0.02) has been studied for the first time by electrochemical method combined with x-ray diffraction and x-ray photoelectron spectroscopy. Working electrodes made of CeO2 and Ce0.98Pt0.02O2-delta mixed with 30% carbon are treated electrochemically between 0.0-1.2 V in potentiostatic (chronoamperometry) and potentiodynamic (cyclic voltametry) mode with reference to saturated calomel electrode. Reversible oxidation of Pt-0 to Pt2+ and Pt4+ state due to the applied positive potential is coupled to simultaneous reversible reduction of Ce4+ to Ce3+ state. CeO2 reduces to CeO2-y (y=0.35) after applying 1.2 V, which is not reversible; Ce0.98Pt0.02O2-delta reaches a steady state with Pt2+:Pt4+ in the ratio of 0.60:0.40 and Ce4+:Ce3+ in the ratio of 0.55:0.45 giving a composition Ce0.98Pt0.02O1.74 at 1.2 V, which is reversible. Composition of Pt ion substituted compound is reversible between Ce0.98Pt0.02O1.95 to Ce0.98Pt0.02O1.74 within the potential range of 0.0-1.2 V. Thus, Ce0.98Pt0.02O2-delta forms a stable electrode for oxidation of H2O to O-2 unlike CeO2. A linear relation between oxidation of Pt2+ to Pt4+ with simultaneous reduction in Ce4+ to Ce3+ is observed demonstrating Pt-CeO2 metal support interaction is due to reversible Pt-0/Pt2+/Pt4+ interaction with Ce4+/Ce3+ redox couple.
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Dimeric and monomeric forms of the enzyme triosephosphate isomerase (TIM) from Plasmodium falciparum (Pf) have been detected under conditions of nanoflow by electrospray mass spectrometry. The dimer (M = 55 663 Da) exhibits a narrow charge state distribution with intense peaks limited to values of 18(+) to 21(+), maximal intensity being observed for charge states 19(+) and 20(+). A monomeric species with a charge state distribution ranging from 11(+) to 16(+) is also observed, which may be assigned to folded dissociated subunits. Complete dimer dissociation results under normal electrospray condition. The effects of solution pH and source temperature have been investigated. The observation of four distinct charge state distributions which may be assigned to a dimer, folded monomer, partially folded monomer and unfolded monomer is reported. Circular dichromism and fluorescence studies of Pf TIM at low pH support the retention of substantial secondary and tertiary structures. Satellite peaks in mass spectra corresponding to hydrated species are also observed and isotope shift upon deuteration is demonstrated. The analysis of all available independent crystal structures of Pf TIM and TIMs from other organisms permits identification of structurally conserved water molecules. Hydration observed in the dimer and folded monomeric forms in the gas phase may correspond to these conserved sites.
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Studies of valence bands and core levels of solids by photoelectron spectroscopy are described at length. Satellite phenomena in the core level spectra have been discussed in some detail and it has been pointed out that the intensity of satellites appearing next to metal and ligand core levels critically depends on the metal-ligand overlap. Use of photoelectron spectroscopy in investigating metal-insulator transitions and spin-state transitions in solids is examined. It is shown that relative intensities of metal Auger lines in transition metal oxides and other systems provide valuable information on the valence bands. Occurrence of interatomic Auger transitions in competition with intraatomic transitions is discussed. Applications of electron energy loss spectroscopy and other techniques of electron spectroscopy in the study of gas-solid interactions are briefly presented.
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This thesis addresses the following broad research question: what did it mean to be a disabled Revolutionary War veteran in the early United States during the period from 1776 to roughly 1840? The study approaches the question from two angles: a state-centred one and an experiential one. In both cases, the theoretical framework employed comes from disability studies. Consequently, disability is regarded as a sociocultural phenomenon rather than a medical condition. The state-centred dimension of the study explores the meaning of disability and disabled veterans to the early American state through an examination of the major military pension laws of the period. An analysis of this legislation, particularly the invalid pension acts of 1793 and 1806, indicates that the early United States represents a key period in the development of the modern disability category. The experiential approach, in contrast, shifts the focus of attention away from the state towards the lived experiences of disabled veterans. It seeks to address the issue of whether or not the disabilities of disabled veterans had any significant material impact on their everyday lives. It does this through a comparison of the situation of 153 disabled veterans with that of an equivalent number of nondisabled veterans. The former group received invalid pensions while the latter did not. In comparing the material conditions of disabled and nondisabled veterans, a wide range of primary sources from military records to memoirs and letters are used. The most important sources in this regard are the pension application papers submitted by veterans in the early nineteenth century. These provide us with a unique insight into the everyday lives of veterans. Looking at the issue of experience through the window of the pension files reveals that there was not much difference in the broad contours of disabled and nondisabled veteran life. This finding has implications for the theorisation of disability that are highlighted and discussed in the thesis. The main themes covered in this study are: the wartime experiences of injured American soldiers, the military pension establishment of the early United States and the legal construction of disability, and the post-war working and family lives of disabled veterans. Keywords: disability, early America, veterans, military pensions, disabled people, Revolutionary War, United States, disability theory.
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A systematic investigation of the effects of antimony dopant on the electronic transport properties of amorphous (GeSe3.5)100−xSbx under high pressure (up to 120 kbar) has been carried out down to liquid-nitrogen temperature for the first time. Differential thermal analysis and x-ray diffraction methods were used for the characterization of freshly prepared and pressure-quenched materials which indicated the presence of structural phase transition in both GeSe3.5 and (GeSe3.5)100−xSbx around 105 kbar pressure. Electrical transport data revealed the strong compositional dependence of the electronic conduction process. A distinct kink in the conductivity temperature plot at pressures>15 kbar was observed in the Sb-doped compositions indicating the presence of different conduction processes. An attempt has been made to interpret the pressure-induced effect in the transport properties of these glasses considering the possible presence of both thermally activated conduction in the extended states and hopping process in the localized tail states. However, the interpretation of the transport data is not straightforward and the pressure dependence of the thermoelectric power will be needed to complete the picture. Journal of Applied Physics is copyrighted by The American Institute of Physics.
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In certain molecular models, and related one-dimensional field theories, localized objects appear with half-integral expectation values of charge. We consider whether these states are eigenstates of charge, with half-integral eigenvalue. We find that it is indeed so for a suitably diffuse definition of the charge operator in question. This diffuse charge operator has a spectrum which approaches a continuum. The analysis is made on a lattice, to avoid divergence ambiguities, and on a finite length, which is only subsequently made large. The half-integral charge phenomenon is not tied to solitons, but can also arise as an end effect.
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Tutkielmani käsittelee yhdysvaltalaisen kirjailijan Paul Austerin (s. 1947) romaanituotannossa esiintyviä esteitä ja rajatiloja. Erityisesti olen kiinnostunut siitä, miten Auster liittää nämä "marginaalitilat" amerikkalaiseen vapauden ja laajentumisen ideologiaan sekä kieleen ja kirjoittamiseen. Austerin romaaneissa esteiden ja rajatilojen käsittely voidaan jakaa kolmeen vaiheeseen. Ensimmäisessä vaiheessa henkilöt ovat vahvojen esteiden rajoittamia tai rakentavat niitä itse. Rajoittuneisuus ei kuitenkaan aina tunnu häiritsevän heitä - itse asiassa monet päähenkilöistä tuntevat itsensä onnellisiksi tai vähintäänkin tyytyväisiksi joutuessaan esteen takia pysähdyttämään vapaan liikkeensä. Toisessa vaiheessa henkilöt pyrkivät ylittämään tai rikkomaan esteen päästäkseen toiselle puolelle. Kuten amerikkalaiset esi-isänsä aikoinaan, he etsivät rajatonta, laajaa ja tyhjää tilaa - "suurta tuntematonta" valloitettavakseen. Tällaisen tilan kohdatessaan he joutuvat kuitenkin usein epävarmuuden valtaan. Kolmas vaihe on tutkielmani kannalta tärkein: välitila, josta käytän työssäni nimitystä "in-betweenity". Tähän vaiheeseen päästään kulkemalla ensin kahden muun vaiheen kautta. Juuri tietoisuus näistä kahdesta muusta vaiheesta synnyttää tämän kolmannen tilan, eräänlaisen rajatilan, jossa tajutaan sekä esteiden että esteettömyyden tärkeys. Tämä välitila on Austerille tyypillinen tila, joka kertoo paitsi amerikkalaisen unelman paradoksaalisuudesta myös (kaunokirjallisen) kielenkäytön prosessista. Monet Austerin kirjojen muurin rakentajista tai purkajista voidaan nähdä kirjailijahahmoina, joiden omituinen suhde esteisiin ja rajoihin kumpuaa juuri siitä rajatilasta, jonka asukkaita he kielentaiteilijoina väistämättä ovat. Tällaisen tilan/tilattomuuden kuvaaminen tekee Austerista oman postmodernin aikamme tärkeän kirjailijan - kirjailijan, joka sen sijaan, että pyrkisi eroon paradokseista, sijoittaa hahmonsa niiden sisään. Rajoihin ja esteisiin liittyvä problematiikka ei kuitenkaan ole pelkästään nykyajan ongelma vaan kysymys, joka ihmisen toisaalta rajoja kaipaavan toisaalta rajattomuutta kaipaavan luonteen vuoksi säilyy aina ajankohtaisena. Avainsanat: Paul Auster, este, muuri, raja, Yhdysvallat
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Introduction: Apathy, agitated behaviours, loneliness and depression are common consequences of dementia. This trial aims to evaluate the effect of a robotic animal on behavioural and psychological symptoms of dementia in people with dementia living in long-term aged care. Methods and analysis: A cluster-randomised controlled trial with three treatment groups: PARO (robotic animal), Plush-Toy (non-robotic PARO) or Usual Care (Control). The nursing home sites are Australian Government approved and accredited facilities of 60 or more beds. The sites are located in South-East Queensland, Australia. A sample of 380 adults with a diagnosis of dementia, aged 60 years or older living in one of the participating facilities will be recruited. The intervention consists of three individual 15 min non-facilitated sessions with PARO or Plush- Toy per week, for a period of 10 weeks. The primary outcomes of interest are improvement in agitation, mood states and engagement. Secondary outcomes include sleep duration, step count, change in psychotropic medication use, change in treatment costs, and staff and family perceptions of PARO or Plush-Toy. Video data will be analysed using Noldus XT Pocket Observer; descriptive statistics will be used for participants’ demographics and outcome measures; cluster and individual level analyses to test all hypotheses and Generalised Linear Models for cluster level and Generalised Estimation Equations and/or Multi-level Modeling for individual level data. Ethics and dissemination: The study participants or their proxy will provide written informed consent. The Griffith University Human Research Ethics Committee has approved the study (NRS/03/14/HREC). The results of the study will provide evidence of the efficacy of a robotic animal as a psychosocial treatment for the behavioural and psychological symptoms of dementia. Findings will be presented at local and international conference meetings and published in peer-reviewed journals.
Introducing a new limit states design concept to railway concrete sleepers: An Australian experience
Resumo:
Over 50 years, a large number of research and development projects with respect to the use of cementitious and concrete materials for manufacturing railway sleepers have been significantly progressed in Australia, Europe, and Japan (Wang, 1996; Murray and Cai, 1998; Wakui and Okuda, 1999; Esveld, 2001; Freudenstein and Haban, 2006; Remennikov and Kaewunruen, 2008). Traditional sleeper materials are timber, steel, and concrete. Cost-efficiency, superior durability, and improved track stability are the main factors toward significant adoption of concrete materials for railway sleepers. The sleepers in a track system, as shown in Figure 1, are subjected to harsh and aggressive external forces and natural environments across a distance. Many systemic problems and technical issues associated with concrete sleepers have been tackled over decades. These include pre-mature failures of sleepers, concrete cancer or ettringite, abrasion of railseats and soffits, impact damages by rail machinery, bond-slip damage, longitudinal and lateral instability of track system, dimensional instability of sleepers, nuisance noise and vibration, and so on (Pfeil, 1997; Gustavson, 2002; Kaewunruen and Remennikov, 2008a,b, 2013). These issues are, however, becoming an emerging risk for many countries (in North and South Americas, Asia, and the Middle East) that have recently installed large volumes of concrete sleepers in their railway networks (Federal Railroad Administration, 2013). As a result, it is vital to researchers and practitioners to critically review and learn from previous experience and lessons around the world.
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A technique for obtaining a uniformly valid solution to the problem of nonlinear propagation of surface acoustic waves excited by a monochromatic line source is presented. The method of solution is an extension of the method of strained coordinates wherein both the dependent and independent variables are expanded in perturbation series. A special transformation is proposed for the independent variables so as to make the expansions uniformly valid and also to satisfy all the boundary conditions. This perturbation procedure, carried out to the second order, yields a solution containing a second harmonic surface wave whose amplitude and phase exhibit an oscillatory variation along the direction of propagation. In addition, the solution also contains a second harmonic bulk wave of constant amplitude but varying phase propagating into the medium.
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This summarizes the results of recently conducted surveys in the United States and Britain to assess employer response in each of these countries to their respective employment disability nondiscrimination legislation.
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HeI photoelectron spectra of the vapour phase complexes of diethylether and diethylsulphide with iodine have been investigated for the first time. The iodine orbital ionization energy decreases on complexation while the donor lone-pair orbital ionization energy increases markedly; the shifts are considerably larger in the sulphide complex as expected on the basis of enthalpy considerations.
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"Ever since the present political boundary separating Mexico and the United States was established in 1848 by the Treaty of Guadalupe Hidalgo and partially amended in 1853 by the Gadsden Purchase, there has been migration of Mexican citizens into the United States. In fact the border between the two nations was completely open until, with the passage of the Immigration Act of 1924, the Border Patrol was established and it became a felony to enter the United States illegally. No quota, however, was applied to immigration from Mexico until 1968. During that year legislation became effective which restricted total annual immigration from all Western Hemisphere nations to 120,000, with a maximum of 40,000 from any one country. Both these figures are regularly exceeded. In 1973, for instance, there were 173,123 legal immigrants from all Western Hemisphere nations, including 70,141 Mexicans. That the real flow exceeds the quotas is explained by the numerous exemptions allowed. With the exception of only three years since 1960, legal immigration from Mexico to the United States has exceeded that of every other nation in the world."