Orthogonality catastrophe in a composite fermion liquid

We discuss the emergence of an orthogonality catastrophe in the response of a composite fermion liquid as the filling factor \nu approaches 1/2m, where m=1,2,3.... A tunneling experiment is proposed in which dramatic changes in the I-V characteristic should be observable as \nu is varied. Explicit I-V characteristics calculated within the so-called Modified Random Phase Approximation, are provided for \nu=1/3 -> \nu=1/2.Comment: Latex two-column 6 pages including 5 figure

Human bladder cancer invasion model using rat bladder in vitro and its use to test mechanisms and therapeutic inhibitors of invasion

As well as being a passive support, the extracellular matrix also regulates key biological processes such as invasion, differentiation and angiogenesis. We have therefore developed an in vitro model of bladder cancer invasion using de-epithelialized rat bladder to allow for tumour cell–extracellular matrix interactions. Onto this we have seeded a panel of human bladder cancer cell lines (RT4, RT112, 253J and EJ28 (T24)) representing progression from well to poorly differentiated phenotypes and used as models of superficial to invasive bladder cancer. The better differentiated cell lines RT4 and RT112 reproducibly grew as stratified epithelium, whereas poorly differentiated EJ28 cells invaded across a broad front. Invasion was not simply related to proliferation rate, measured either as doubling time on plastic (non-invasive 253J and invasive EJ28 having the same doubling time) or by Ki-67 proliferation index within the model. We used the model to test the ability of 4 compounds that interfere with tumour cell–extracellular matrix interactions (suramin, N-acetylcysteine and the urokinase plasminogen activator pathway antagonists Å5 compound and monoclonal antibody Mab 3936) to inhibit invasion. At non-toxic concentrations, all significantly inhibited invasion (P< 0.05), although to varying degrees, suramin and Å5 almost completely and N-acetylcysteine the least. In conclusion, this model shows the urokinase system is important for bladder invasion and can be used to investigate other mechanisms of bladder cancer invasion and also for the testing of intravesical drugs. © 2001 Cancer Research Campaign http://www.bjcancer.co

Eukaryotic initiation factor-4E in superficial and muscle invasive bladder cancer and its correlation with vascular endothelial growth factor expression and tumour progression

Vascular endothelial growth factor (VEGF) is an important factor mediating tumour angiogenesis. VEGF mRNA is differentially expressed in bladder cancer with high expression in superficial tumours (stage pTaand pT1) contrasting with low expression in muscle invasive tumours (stage ≥ pT2). To investigate mechanisms regulating VEGF expression in bladder cancer, VEGF mRNA and protein were measured in normal bladder (n = 12) and primary bladder cancers (n = 57). VEGF protein levels correlated with mRNA expression in normal bladder (r = 0.68, P = 0.02) and bladder cancer (r = 0.46, P = 0.0007). Whilst VEGF mRNA expression was threefold higher in superficial compared to muscle invasive bladder cancers (P = 0.0001) there was no difference in VEGF protein (P = 0.81). Accordingly, the median protein:mRNA ratios increased more than 15-fold with increasing tumour stage (P< 0.0001) suggesting translational regulation. Expression of the eukaryotic initiation factor-4E (eIF-4E), a factor implicated in the translational regulation of VEGF, was greater in tumours than normal bladder (P< 0.0001) and correlated with VEGF protein:mRNA ratios (n = 43, r = 0.54, P = 0.0004) pointing to its role in the regulation of VEGF. In superficial tumours (n = 37) high expression of eIF-4E was associated with a poor prognosis and reduced stage progression-free survival (P = 0.04, Cox proportional hazards model). The study demonstrates that eIF-4E may be involved in translational regulation of VEGF in bladder cancer and might have a role as a prognostic factor in bladder cancer. © 2000 Cancer Research Campaig

The transition from the adiabatic to the sudden limit in core level photoemission: A model study of a localized system

We consider core electron photoemission in a localized system, where there is a charge transfer excitation. The system is modelled by three electron levels, one core level and two outer levels. The model has a Coulomb interaction between these levels and the continuum states into which the core electron is emitted. The model is simple enough to allow an exact numerical solution, and with a separable potential an analytic solution. We calculate the ratio r(omega) between the weights of the satellite and the main peak as a function of the photon energy omega. The transition from the adiabatic to the sudden limit takes place for quite small photoelectron kinetic energies. For such small energies, the variation of the dipole matrix element is substantial and described by the energy scale Ed. Without the coupling to the photoelectron, the corresponding ratio r0(omega) is determined by Ed and the satellite excitation energy dE. When the interaction potential with the continuum states is introduced, a new energy scale Es=1/(2Rs^2) enters, where Rs is a length scale of the interaction potential. At threshold there is typically a (weak) constructive interference between intrinsic and extrinsic contributions, and the ratio r(omega)/r0(omega) is larger than its limiting value for large omega. The interference becomes small or weakly destructive for photoelectron energies of the order Es. For larger energies r(omega)/r0(omega) therefore typically has a weak undershoot. If this undershoot is neglected, r(omega)/r0(omega) reaches its limiting value on the energy scale Es.Comment: 18 pages, latex2e, 13 eps figure

Electronic structure of the strongly hybridized ferromagnet CeFe2

We report on results from high-energy spectroscopic measurements on CeFe2, a system of particular interest due to its anomalous ferromagnetism with an unusually low Curie temperature and small magnetization compared to the other rare earth-iron Laves phase compounds. Our experimental results indicate very strong hybridization of the Ce 4f states with the delocalized band states, mainly the Fe 3d states. In the interpretation and analysis of our measured spectra, we have made use of two different theoretical approaches: The first one is based on the Anderson impurity model, with surface contributions explicitly taken into account. The second method consists of band-structure calculations for bulk CeFe2. The analysis based on the Anderson impurity model gives calculated spectra in good agreement with the whole range of measured spectra, and reveals that the Ce 4f -- Fe 3d hybridization is considerably reduced at the surface, resulting in even stronger hybridization in the bulk than previously thought. The band-structure calculations are ab initio full-potential linear muffin-tin orbital calculations within the local-spin-density approximation of the density functional. The Ce 4f electrons were treated as itinerant band electrons. Interestingly, the Ce 4f partial density of states obtained from the band-structure calculations also agree well with the experimental spectra concerning both the 4f peak position and the 4f bandwidth, if the surface effects are properly taken into account. In addition, results, notably the partial spin magnetic moments, from the band-structure calculations are discussed in some detail and compared to experimental findings and earlier calculations.Comment: 10 pages, 8 figures, to appear in Phys. Rev. B in December 200

Resonant Auger spectroscopy at the L2,3 shake-up thresholds as a probe of electron correlation effects in nickel

The excitation energy dependence of the three-hole satellites in the L3-M4,5M4,5 and L2-M4,5M4,5 Auger spectra of nickel metal has been measured using synchrotron radiation. The satellite behavior in the non-radiative emission spectra at the L3 and L2 thresholds is compared and the influence of the Coster-Kronig channel explored. The three-hole satellite intensity at the L3 Auger emission line reveals a peak structure at 5 eV above the L3 threshold attributed to resonant processes at the 2p53d9 shake-up threshold. This is discussed in connection with the 6-eV feature in the x-ray absorption spectrum.Comment: 8 pages, 4 figures; http://prb.aps.org/abstract/PRB/v58/i7/p3677_

New insights into the impact of neuro-inflammation in rheumatoid arthritis.

Rheumatoid arthritis (RA) is considered to be, in many respects, an archetypal autoimmune disease that causes activation of pro-inflammatory pathways resulting in joint and systemic inflammation. RA remains a major clinical problem with the development of several new therapies targeted at cytokine inhibition in recent years. In RA, biologic therapies targeted at inhibition of tumor necrosis factor alpha (TNFα) have been shown to reduce joint inflammation, limit erosive change, reduce disability and improve quality of life. The cytokine TNFα has a central role in systemic RA inflammation and has also been shown to have pro-inflammatory effects in the brain. Emerging data suggests there is an important bidirectional communication between the brain and immune system in inflammatory conditions like RA. Recent work has shown how TNF inhibitor therapy in people with RA is protective for Alzheimer's disease. Functional MRI studies to measure brain activation in people with RA to stimulus by finger joint compression, have also shown that those who responded to TNF inhibition showed a significantly greater activation volume in thalamic, limbic, and associative areas of the brain than non-responders. Infections are the main risk of therapies with biologic drugs and infections have been shown to be related to disease flares in RA. Recent basic science data has also emerged suggesting that bacterial components including lipopolysaccharide induce pain by directly activating sensory neurons that modulate inflammation, a previously unsuspected role for the nervous system in host-pathogen interactions. In this review, we discuss the current evidence for neuro-inflammation as an important factor that impacts on disease persistence and pain in RA

The Kondo Resonance in Electron Spectroscopy

The Kondo resonance is the spectral manifestation of the Kondo properties of the impurity Anderson model, and also plays a central role in the dynamical mean-field theory (DMFT) for correlated electron lattice systems. This article presents an overview of electron spectroscopy studies of the resonance for the 4f electrons of cerium compounds, and for the 3d electrons of V_2O_3, including beginning efforts at using angle resolved photoemission to determine the k-dependence of the resonance. The overview includes the comparison and analysis of spectroscopy data with theoretical spectra as calculated for the impurity model and as obtained by DMFT, and the Kondo volume collapse calculation of the cerium alpha-gamma phase transition boundary, with its spectroscopic underpinnings.Comment: 32 pages, 11 figures, 151 references; paper for special issue of J. Phys. Soc. Jpn. on "Kondo Effect--40 Years after the Discovery

Compensatory shifts in visual perception are associated with hallucinations in Lewy body disorders

Abstract Visual hallucinations are a common, distressing, and disabling symptom of Lewy body and other diseases. Current models suggest that interactions in internal cognitive processes generate hallucinations. However, these neglect external factors. Pareidolic illusions are an experimental analogue of hallucinations. They are easily induced in Lewy body disease, have similar content to spontaneous hallucinations, and respond to cholinesterase inhibitors in the same way. We used a primed pareidolia task with hallucinating participants with Lewy body disorders (n = 16), non-hallucinating participants with Lewy body disorders (n = 19), and healthy controls (n = 20). Participants were presented with visual “noise” that sometimes contained degraded visual objects and were required to indicate what they saw. Some perceptions were cued in advance by a visual prime. Results showed that hallucinating participants were impaired in discerning visual signals from noise, with a relaxed criterion threshold for perception compared to both other groups. After the presentation of a visual prime, the criterion was comparable to the other groups. The results suggest that participants with hallucinations compensate for perceptual deficits by relaxing perceptual criteria, at a cost of seeing things that are not there, and that visual cues regularize perception. This latter finding may provide a mechanism for understanding the interaction between environments and hallucinations

The Lingering Environmental Impact of Repressive Governance: The Environmental Legacy of the Apartheid Era for the New South Africa

This article aims to explore the historical link between contemporary environmental problems and the environmental, economic and political policies of the apartheid government. The analysis draws on an examination of the detrimental environmental impacts of the apartheid era and how international isolation impacted on governmental environmental management in the country, before turning attention to the way in which the ANC government has managed the South African natural and human environments in the period after 1994. The article shows that despite many important new developments since 1994, that there are high levels of continuity between the environmental management practices of the old and the new regimes. This state of affairs negatively impacts on the ability of the ANC government to provide every South African citizen with the clean and safe environment guaranteed to all within the 1996 Bill of Rights.This article also appeared unchanged as a chapter in the following edited collection: Jan Oosthoek and Barry K. Gills (eds), _The Globalization of Environmental Crisis_ (Abingdon: Routledge, 2008), pp. 109-120