Metallic phase in the two-dimensional ionic Hubbard model

We investigate the phases of the ionic Hubbard model in a two-dimensional square lattice using determinant quantum Monte Carlo (DQMC). At half-filling, when the interaction strength or the staggered potential dominate we find Mott and band insulators, respectively. When these two energies are of the same order we find a metallic region. Charge and magnetic structure factors demonstrate the presence of antiferromagnetism only in the Mott region, although the externally imposed density modulation is present everywhere in the phase diagram. Away from half-filling, other insulating phases are found. Kinetic energy correlations do not give clear signals for the existence of a bond-ordered phase

Transport and magnetic properties in YBaCo2O5.45: Focus on the high-temperature transition

The electronic transport properties and the magnetic susceptibility were measured in detail in $YBaCo_2O_{5.45}$. Close to the so-called metal-insulator transition, strong effects of resistance relaxation, a clear thermal hysteresis and a sudden increase of the resistance noise are observed. This is likely due to the first order character of the transition and to the underlying phases coexistence. Despite these out of equilibrium features, a positive and linear magneto-resistance is also observed, possibly linked to the heterogeneity of the state. From a magnetic point of view, the paramagnetic to ordered magnetic state transition is observed using non linear susceptibilty. This transition shows the characteristics of a continuous transition, and time dependent effects can be linked with the dynamics of magnetic domains in presence of disorder. Thus, when focusing on the order of the transitions, the electronic one and the magnetic one can not be directly associated.Comment: accepted for publication in PR

The eSMAF: a software for the assessment and follow-up of functional autonomy in geriatrics

BACKGROUND: Functional status or disability forms the core of most assessment instruments used to identify mix and level of resources and services needed by older adults who possess common characteristics. The Functional Autonomy Measurement System (SMAF) is a 29-item scale measuring functional ability in five different areas. It has been recommended for use for home care, for allocation of chronic beds, for developing care plans in institutional settings and for epidemiological and evaluative studies. The SMAF can also be used with a case-mix classification system (Iso-SMAF) to allocate resources based on patients' functional autonomy characteristics. The objective of this project was to develop a software version of the SMAF to facilitate the evaluation of the functional status of older adults in health services research and to optimize the clinical decision-making process. RESULTS: The eSMAF was developed over an 24-month period using a modified waterfall software engineering process. Requirements and functional specifications were determined using focus groups of stakeholders. Different versions of the software were iteratively field-tested in clinical and research environments and software adaptations made accordingly. User documentation and online help were created to assist the deployment of the software. The software is available in French or English versions under a 30-day unregistered demonstration license or a free restricted registered academic license. It can be used locally on a Windows-based PC or over a network to input SMAF data into a database, search and aggregate client data according to clinical and/or administrative criteria, and generate summary or detailed reports of selected data sets for print or export to another database. CONCLUSION: In the last year, the software has been successfully deployed in the clinical workflow of different institutions in research and clinical applications. The software performed relatively well in terms of stability and performance. Barriers to implementation included antiquated computer hardware, low computer literacy and access to IT support. Key factors for the deployment of the software included standardization of the workflow, user training and support

Strongly correlated properties of the thermoelectric cobalt oxide Ca3Co4O9

We have performed both in-plane resistivity, Hall effect and specific heat measurements on the thermoelectric cobalt oxide Ca$_{3}$Co$_{4}$O$_{9}$. Four distinct transport regimes are found as a function of temperature, corresponding to a low temperature insulating one up to $T_{min}\approx$63 K, a strongly correlated Fermi liquid up to $T^*\approx$140 K, with $\rho=\rho_0+AT^2$ and $A\approx 3.63$ $10^{-2} \mu \Omega cm/K^{2}$, followed by an incoherent metal with $k_Fl\leq 1$ and a high temperature insulator above T$^{**}\approx$510 K . Specific heat Sommerfeld coefficient $\gamma = 93$ mJ/(mol.K$^{2}$) confirms a rather large value of the electronic effective mass and fulfils the Kadowaki-Woods ratio $A/\gamma^2 \approx 0.45$ 10$^{-5}$ $\mu \Omega cm.K^2/(mJ^2mol^{-2})$. Resistivity measurements under pressure reveal a decrease of the Fermi liquid transport coefficient A with an increase of $T^*$ as a function of pressure while the product $A(T^*)^2/a$ remains constant and of order $h/e^2$. Both thermodynamic and transport properties suggest a strong renormalization of the quasiparticles coherence scale of order $T^*$ that seems to govern also thermopower.Comment: 5 pages, 6 figures, accepted for publication in Physical Review

Cathodoluminescence Mapping of Cherenkov-Radiation Generated Bloch-Modes in Planar Photonic Crystals by Fast Electrons

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 - August 5, 201

Combined Impact of Lifestyle Factors on Cancer Mortality in Men

PURPOSE - The impact of lifestyle factors on cancer mortality in the U.S. population has not been thoroughly explored. We examined the combined effects of cardiorespiratory fitness, never smoking, and normal waist girth on total cancer mortality in men. METHODS - We followed a total of 24,731 men ages 20-82 years who participated in the Aerobics Center Longitudinal Study. A low-risk profile was defined as never smoking, moderate or high fitness, and normal waist girth, and they were further categorized as having 0, 1, 2, or 3 combined low-risk factors. RESULTS - During an average of 14.5 years of follow-up, there were a total of 384 cancer deaths. After adjustment for age, examination year, and multiple risk factors, men who were physically fit, never smoked, and had a normal waist girth had a 62% lower risk of total cancer mortality (95% confidence interval [CI], 45%-73%) compared with men with zero low-risk factors. Men with all 3 low-risk factors had a 12-year (95% CI: 8.6-14.6) longer life expectancy compared with men with 0 low-risk factors. Approximately 37% (95% CI, 17%-52%) of total cancer deaths might have been avoided if the men had maintained all three low-risk factors. CONCLUSIONS - Being physically fit, never smoking, and maintaining a normal waist girth is associated with lower risk of total cancer mortality in men

Revealing Superfluid--Mott-Insulator Transition in an Optical Lattice

We study (by an exact numerical scheme) the single-particle density matrix of $\sim 10^3$ ultracold atoms in an optical lattice with a parabolic confining potential. Our simulation is directly relevant to the interpretation and further development of the recent pioneering experiment by Greiner et al. In particular, we show that restructuring of the spatial distribution of the superfluid component when a domain of Mott-insulator phase appears in the system, results in a fine structure of the particle momentum distribution. This feature may be used to locate the point of the superfluid--Mott-insulator transition.Comment: 4 pages (12 figures), Latex. (A Latex macro is corrected

Self-rated health status and cardiorespiratory fitness as predictors of mortality in men

Self-rated health (SRH) and cardiorespiratory fitness (fitness) are independent risk factors for all-cause mortality. The purpose of this report is to examine the single and joint effects of these exposures on mortality risk. The study included 18 488 men who completed a health survey, clinical examination and a maximal exercise treadmill test during 1987–2003. Cox regression analysis was used to quantify the associations of SRH and fitness with all-cause mortality. There were 262 deaths during 17 years of follow-up. There was a significant inverse trend (ptrend \u3c0.05) for mortality across SRH categories after adjustment for age, examination year, body mass index, physical activity, smoking, alcohol consumption, abnormal ECG, hypertension, hypercholesterolaemia, cardiovascular disease, diabetes and cancer. Adjustment for fitness attenuated the association (p value =0.09). The authors also observed an inverse association between fitness and mortality after controlling for the same covariates and SRH (ptrend = 0.006). The combined analysis of SRH and fitness showed that fit men with good or excellent SRH had a 58% lower risk of mortality than their counterparts. SRH and fitness were both associated with all-cause mortality in men. Fit men with good or excellent SRH live longer than unfit men with poor or fair SRH