Exact Transformation for Spin-Charge Separation of Spin-half Fermions without Constraints

We demonstrate an exact local transformation which maps a purely Fermionic manybody system to a system of spinfull Bosons and spinless Fermions, demonstrating a possible path to a non-Fermi liquid state. We apply this to the half-filled Hubbard model and show how the transformation maps the ordinary spin half Fermionic degrees of freedom exactly and without introducing Hilbert space constraints to a charge-like ``quasicharge'' fermion and a spin-like ``quasispin'' Boson while preserving all the symmetries of the model. We present approximate solutions with localized charge which emerge naturally from the Hubbard model in this form. Our results strongly suggest that charge tends to remain localized for large values of the Hubbard U

Advection Dominated Accretion Flows Around Kerr Black Holes

We derive all relevant equations needed for constructing a global general relativistic model of advectively cooled, very hot, optically thin accretion disks around black holes and present solutions which describe advection dominated flows in the gravitational field of a Kerr black hole.Comment: ApJ submitte

Different Disease Profiles for Women and Men with Abdominal Aortic Aneurysms

ObjectiveThe overall aim with this study was to investigate causes of death and mortality rates for women and men treated for abdominal aortic aneurysm (AAA) in Sweden.Materials and methodAll patients treated for ruptured and non-ruptured AAA 1987–2002 in Sweden were identified in national registries (n=12917). Age, sex, diagnosis, surgical procedure and mortality were analysed on a patient specific level. Logistic regression and analysis of standardised mortality rates (SMR) were performed.ResultsPost operative mortality was similar between the sexes. Age (p<0.0001), and surgery for rupture (p=0.0005), but not gender (p=0.65) were significant risk factor for poor long term survival. SMR revealed increased risk for both sexes compared to the population with significantly higher values for women than men (2.26, CI 2.10–2.43 vs. 1.63, CI 1.57–1.68, p<0.0001). The higher risk for women could be explained by the higher risk for aneurysm related death (ie.thoracic or abdominal aorta) compared to men (Hazard ratio 1.57 vs. 1.0, p<0.0001).ConclusionWomen do not have an increased surgical risk compared to men, but treated women have an increased risk of premature death compared to men and women in the population. They also have a higher risk for aneurysm related death compared to men with AAA

Anharmonic softening of Raman active phonons in Iron-Pnictides; estimating the Fe isotope effect due to anharmonic expansion

We present Raman measurements on the iron-pnictide superconductors CeFeAsO_{1-x}F_{x} and NdFeAsO{1-x}F_{x}. Modeling the Fe-As plane in terms of harmonic and a cubic anharmonic Fe-As interaction we calculate the temperature dependence of the energy and lifetime of the Raman active Fe B_{1g} mode and fit to the observed energy shift. The shifts and lifetimes are in good agreement with those measured also in other Raman studies which demonstrate that the phonon spectrum is well represented by phonon-phonon interactions without any significant electronic contribution. We also estimate the anharmonic expansion from Fe (56->54) isotope substitution to \Delta a=5.1 10^{-4}\AA and \Delta d_{Fe-As}= 2.510^{-4}\AA and the shift of harmonic zero point fluctuations of bond lengths <=3 10^{-5}\AA^2, giving a total relative average decrease of electronic hopping integrals of |\delta t|/t<= 2.0 10^{-4}. The results poses a serious challenge for any theory of superconductivity in the pnictides that does not include electron-phonon interactions to produce a sizable Fe-isotope effect.Comment: 7 pages, 6 figure

Distributional exact diagonalization formalism for quantum impurity models

We develop a method for calculating the self-energy of a quantum impurity coupled to a continuous bath by stochastically generating a distribution of finite Anderson models that are solved by exact diagonalization, using the noninteracting local spectral function as a probability distribution for the sampling. The method enables calculation of the full analytic self-energy and single-particle Green's function in the complex frequency plane, without analytic continuation, and can be used for both finite and zero temperature at arbitrary fillings. Results are in good agreement with imaginary frequency data from continuous-time quantum Monte Carlo calculations for the single impurity Anderson model and the two-orbital Hubbard model within dynamical mean field theory (DMFT) as well as real frequency data for self energy of the single band Hubbard model within DMFT using numerical renormalization group. The method should be applicable to a wide range of quantum impurity models and particularly useful when high-precision real frequency results are sought.Comment: Two band calculation updated, 4 pages, 4 figure

Fermi momentum resolved charge order for spin disordered stripes

For a doped antiferromagnet with short-range spin stripe correlations and long-range charge stripe order we find that the manifestation of charge order changes abruptly as a function of momentum along the Fermi surface. The disorder averaged local density of states is almost perfectly homogeneous when integrated only over states which contribute to the ``nodal'' spectral weight whereas it displays long range charge stripe order when integrated only over states which contribute to the ``antinodal'' spectral weight. An effectively two dimensional nodal liquid can thus coexist with static charge stripes provided there is no static spin order. We also study commensurate spin and charge stripe ordered systems where the Fermi surface consists of a nodal hole pocket and an open ``stripe band'' section. Due to the stripe order the relation between hole density and size of a pocket will be reduced compared to a paramagnet by a factor of two for even charge period and four for odd charge period and we find an estimated upper limit on the area fraction of a hole pocket of 1.6% for charge period four and 4% for charge period five. We also discuss why electron pockets are not expected for a stripe ordered system and show that the open Fermi surface section may be electron like with a negative Hall coefficient.Comment: 9 pages, 5 figures, added references and extended discussion of Hall coefficient for stripe ordered system; v3 final, improved figure

Residential movements in connection to renovation of rented multi-residential housing: A pilot study

Residential movement and displacement as an effect of renovation has earned attention and also affected renovation practices in Sweden. While statistical studies have linked deep renovation to residential movement and displacement, there are no recent studies that investigate why people move or remain in housing areas that are renovated, and if and how the relocation is determined by the renovation. A pilot study was initiated as a means to develop a methodology to study residential movement in connection to renovation. In this paper, methodological considerations are discussed based on 31 interviews (face-to-face and telephone) with movers related to 34 municipally owned rented housing areas about to undergo renovation, as well results from a questionnaire sent to two finalised renovation projects (N=113). So far, the pilot study indicate that few relocations can be linked to the up-coming or finalised renovation in the studies cases. The questionnaire that was sent out to remaining tenants had a low response rate of 29%, and the efficiency of using questionnaires is discussed

Potential savings without compromising the quality of care

SUMMARY Aims: This study was designed to analyse the association between adherence to guidelines for rational drug use and surrogate outcome markers for hypertension, diabetes and hypercholesterolaemia. Methods: The study used a cross-sectional ecological design. Data from dispensed prescriptions and medical records were analysed from 24 primary healthcare centres with a combined registered population of 330,000 patients in 2006. Guideline adherence was determined calculating the proportion of the prescribed volume of antidiabetic agents, antihypertensives and lipid-lowering agents representing the 14 different drugs included in the guidelines for these three areas. Patient outcome was assessed using surrogate marker data on HbA1C, blood pressure (BP) and s-cholesterol. The association between the guidelines adherence and outcomes measures was analysed by logistic regression. Results: The proportion of guideline antidiabetic drugs in relation to all antidiabetic drugs prescribed varied between 80% and 97% among the practices, the ratio of angiotensin converting enzyme (ACE)-inhibitors to all renin–angiotensin drugs 40–77% and the ratio of simvastatin to all statins 58–90%. The proportion of patients reaching targets for HbA1C, BP and s-cholesterol varied between 34% and 66%, 36% and 57% and 46% and 71% respectively. No significant associations were found between adherence to the guidelines and outcome. The expenditures for antihypertensives and lipid-lowering drugs could potentially be reduced by 10% and 50% respectively if all practices adhered to the guidelines as the top performing practices. Conclusion: A substantial amount of money can be saved in primary care without compromising the quality of care by using recommended first-line drugs for the treatment diabetes, hypertension and hypercholesterolaemia. What's known • There are substantial price differences between branded and off-patent drugs for the treatment of diabetes, hypertension and hypercholesterolaemia. • There is a wide variation in adherence to prescribe targets in primary healthcare. • There is a limited knowledge on the relation between adherence to prescribing targets or guidelines, patient outcomes and potential savings that could be achieved. What's new • No significant associations were found at a practice level between adherence to the guidelines and outcomes in terms of patients reaching target levels for surrogate markers. • A substantial amount of money can be saved in primary care without compromising the quality of care by using recommended off-patent drugs for the treatment of diabetes, hypertension and hypercholesterolaemia

Kondo effect in crossed Luttinger liquids

We study the Kondo effect in two crossed Luttinger liquids, using Boundary Conformal Field Theory. We predict two types of critical behaviors: either a two-channel Kondo fixed point with a nonuniversal Wilson ratio, or a new theory with an anomalous response identical to that found by Furusaki and Nagaosa (for the Kondo effect in a single Luttinger liquid). Moreover, we discuss the relevance of perturbations like channel anisotropy, and we make links with the Kondo effect in a two-band Hubbard system modeled by a channel-dependent Luttinger Hamiltonian. The suppression of backscattering off the impurity produces a model similar to the four-channel Kondo theory.Comment: 7 pages, RevteX, to be published in Physical Review