Friedel oscillations in a two-band Hubbard model for CuO chains

Friedel oscillations induced by open boundary conditions in a two-band Hubbard model for CuO chains are numerically studied. We find that for physically realistic parameters and close to quarter filling, these oscillations have a 2k_F modulation according with experimental results on YBa_2Cu_3O_{7-delta}. In addition, we predict that, for the same parameters, as hole doping is reduced from quarter filling to half filling, Friedel oscillations would acquire a 4k_F modulation, typical of a strongly correlated electrons regime. The 4k_F modulation dominates also in the electron doped region. The range of parameters varied is very broad, and hence the results reported could apply to other cuprates and other strongly correlated compounds with quasi-one dimensional structures. On a more theoretical side, we stress the fact that the copper and oxygen subsystems should be described by two different Luttinger liquid exponents.Comment: 7 pages, 7 eps figure

Residual cognitive deficits 50 years after lead poisoning during childhood

The long term neurobehavioural consequences of childhood lead poisoning are not known. In this study adult subjects with a documented history of lead poisoning before age 4 and matched controls were examined with an abbreviated battery of neuropsychological tests including measures of attention, reasoning, memory, motor speed, and current mood. The subjects exposed to lead were inferior to controls on almost all of the cognitive tasks. This pattern of widespread deficits resembles that found in children evaluated at the time of acute exposure to lead rather than the more circumscribed pattern typically seen in adults exposed to lead. Despite having completed as many years of schooling as controls, the subjects exposed to lead were lower in lifetime occupational status. Within the exposed group, performance on the neuropsychological battery and occupational status were related, consistent with the presumed impact of limitations in neuropsychological functioning on everyday life. The results suggest that many subjects exposed to lead suffered acute encephalopathy in childhood which resolved into a chronic subclinical encephalopathy with associated cognitive dysfunction still evident in adulthood. These findings lend support to efforts to limit exposure to lead in childhood

Worse than HIV' or 'not as serious as other diseases'? Conceptualization of cervical cancer among newly screened women in Zambia

Invasive cervical cancer is the second most common cancer among women worldwide, with approximately 85% of the disease burden occurring in developing countries. To date, there have been few systematic efforts to document African women's conceptualization of cervical cancer after participation in a visual inspection with acetic acid (VIA)-based " see and treat" cervical cancer prevention program. In this study, conducted between September, 2009-July, 2010, focus groups and in-depth interviews were conducted with 60 women who had recently undergone cervical cancer screening at a government-operated primary health care clinic in Lusaka, Zambia. Interviewers elicited participants' causal representations of cervical cancer, associated physical signs and symptoms, perceived physical and psychological effects, and social norms regarding the disease. The lay model of illness causation portrayed by participants after recent exposure to program promotion messages departed in several ways from causal models described in other parts of the world. However, causal conceptualizations included both lay and biomedical elements, suggesting a possible shift from a purely traditional causal model to one that incorporates both traditional concepts and recently promoted biomedical concepts. Most, but not all, women still equated cervical cancer with death, and perceived it to be a highly stigmatized disease in Zambia because of its anatomic location, dire natural course, connections to socially-condemned behaviors, and association with HIV/AIDS. No substantive differences of disease conceptualization existed according to HIV serostatus, though HIV positive women acknowledged that their immune status makes them more aware of their health and more likely to seek medical attention. Further attention should be dedicated to the processes by which women incorporate new knowledge into their representations of cervical cancer

Motivations and experiences of women who accessed "see and treat" cervical cancer prevention services in Zambia

Background: In Zambia, a country with a generalized HIV epidemic, age-adjusted cervical cancer incidence is among the highest worldwide. In 2006, the University of Alabama at Birmingham-Center for Infectious Disease Research in Zambia and the Zambian Ministry of Health launched a visual inspection with acetic acid (VIA) -based "see and treat" cervical cancer prevention program in Lusaka. All services were integrated within existing government-operated primary health care facilities. Objective: Study aims were to (i) identify women's motivations for cervical screening, (ii) document women's experiences with screening and (iii) describe the potentially reciprocal influences between women undergoing cervical screening and their social networks. Design and methods: Focus group discussions (FGD) and in-depth interviews (IDI) were conducted with women who accepted screening and with care providers. Low-level content analysis was performed to identify themes evoked by participants. Between September 2009 and July 2010, 60 women and 21 care providers participated in 8 FGD and 10 IDI. Results: Women presented for screening with varying needs and expectations. A majority discussed their screening decisions and experiences with members of their social networks. Key reinforcing factors and obstacles to VIA screening were identified. Conclusions: Interventions are needed to gain support for the screening process from influential family members and peers

Dispersion of Ordered Stripe Phases in the Cuprates

A phase separation model is presented for the stripe phase of the cuprates, which allows the doping dependence of the photoemission spectra to be calculated. The idealized limit of a well-ordered array of magnetic and charged stripes is analyzed, including effects of long-range Coulomb repulsion. Remarkably, down to the limit of two-cell wide stripes, the dispersion can be interpreted as essentially a superposition of the two end-phase dispersions, with superposed minigaps associated with the lattice periodicity. The largest minigap falls near the Fermi level; it can be enhanced by proximity to a (bulk) Van Hove singularity. The calculated spectra are dominated by two features -- this charge stripe minigap plus the magnetic stripe Hubbard gap. There is a strong correlation between these two features and the experimental photoemission results of a two-peak dispersion in La$_{2-x}$Sr$_x$CuO$_4$, and the peak-dip-hump spectra in Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$. The differences are suggestive of the role of increasing stripe fluctuations. The 1/8 anomaly is associated with a quantum critical point, here expressed as a percolation-like crossover. A model is proposed for the limiting minority magnetic phase as an isolated two-leg ladder.Comment: 24 pages, 26 PS figure

Active Galactic Nuclei at the Crossroads of Astrophysics

Over the last five decades, AGN studies have produced a number of spectacular examples of synergies and multifaceted approaches in astrophysics. The field of AGN research now spans the entire spectral range and covers more than twelve orders of magnitude in the spatial and temporal domains. The next generation of astrophysical facilities will open up new possibilities for AGN studies, especially in the areas of high-resolution and high-fidelity imaging and spectroscopy of nuclear regions in the X-ray, optical, and radio bands. These studies will address in detail a number of critical issues in AGN research such as processes in the immediate vicinity of supermassive black holes, physical conditions of broad-line and narrow-line regions, formation and evolution of accretion disks and relativistic outflows, and the connection between nuclear activity and galaxy evolution.Comment: 16 pages, 5 figures; review contribution; "Exploring the Cosmic Frontier: Astrophysical Instruments for the 21st Century", ESO Astrophysical Symposia Serie

Supermassive Black Hole Binaries: The Search Continues

Gravitationally bound supermassive black hole binaries (SBHBs) are thought to be a natural product of galactic mergers and growth of the large scale structure in the universe. They however remain observationally elusive, thus raising a question about characteristic observational signatures associated with these systems. In this conference proceeding I discuss current theoretical understanding and latest advances and prospects in observational searches for SBHBs.Comment: 17 pages, 4 figures. To appear in the Proceedings of 2014 Sant Cugat Forum on Astrophysics. Astrophysics and Space Science Proceedings, ed. C.Sopuerta (Berlin: Springer-Verlag

Improved W boson mass measurement with the D0 detector

We have measured the W boson mass using the D0 detector and a data sample of 82 pb^-1 from the Tevatron collider. This measurement used W -> e nu decays, where the electron is close to a boundary of a central electromagnetic calorimeter module. Such 'edge' electrons have not been used in any previous D0 analysis, and represent a 14% increase in the W boson sample size. For these electrons, new response and resolution parameters are determined, and revised backgrounds and underlying event energy flow measurements are made. When the current measurement is combined with previous D0 W boson mass measurements, we obtain M_W = 80.483 +/- 0.084 GeV. The 8% improvement from the previous D0 measurement is primarily due to the improved determination of the response parameters for non-edge electrons using the sample of Z bosons with non-edge and edge electrons.Comment: submitted to Phys. Rev. D; 20 pages, 18 figures, 9 table