Electronic Raman scattering on under-doped Hg-1223 high-Tc superconductors:investigations on the symmetry of the order parameter

In order to obtain high quality, reliable electronic Raman spectra of a high-Tc superconductor compound, we have studied strongly under-doped HgBa2Ca2Cu3O8+d. This choice was made such as to i)minimize oxygen disorder in the Hg-plane generated by oxygen doping ii) avoid the need of phonon background subtraction from the raw data iii)eliminate traces of parasitic phases identified and monitored on the crystal surface. Under these experimental conditions we are able to present the pure electronic Raman response function in the B2g, B1g, A1g+B2g and A1g+B1g channels. The B2g spectrum exhibits a linear frequency dependence at low energy whereas the B1g one shows a cubic-like dependence. The B2g and B1g spectra display two well defined maxima at 5.6kBTc and 9kBTc respectively. In mixed A1g channels an intense electronic peak centered around 6.4 kBTc is observed. The low energy parts of the spectra correspond to the electronic response expected for a pure dx2-y2 gap symmetry and can be fitted up to the gap energy for the B1g channel. However, in the upper parts, the relative position of the B1g and B2g peaks needs expanding the B2g Raman vertex to second order Fermi surface harmonics to fit the data with the dx2-y2 model. The sharper and more intense A1g peak appears to challenge the Coulomb screening efficiency present for this channel. As compared to previous data on more optimally doped, less stoichiometric Hg-1223 compounds, this work reconciles the electronic Raman spectra of under- doped Hg-1223 crystals with the dx2-y2 model, provided that the oxygen doping is not too strong. This apparent extreme sensitivity of the electronic Raman spectra to the low lying excitations induced by oxygen doping in the superconducting state is emphasized here and remains an open question.Comment: 12 pages, 5 figure

BaCu3O4: High Temperature Magnetic Order in One-Dimensional S=1/2 Diamond-Chains

The magnetic properties of the alkaline earth oxocuprate BaCu3O4 are investigated. We show that the characteristic Cu3O4 layers of this material can be described with diamond chains of antiferromagnetically coupled Cu 1/2 spins with only a weak coupling between two adjacent chains. These Cu3O4 layers seem to represent a so far unique system of weakly coupled one-dimensional magnetic objects where the local AF ordering of the Cu2+ ions leads to an actual net magnetic moment of an isolated diamond chain. We demonstrate a magnetic transition at a high N\'eel temperature T_{N}=336 K

A core genetic module : the Mixed Feedback Loop

The so-called Mixed Feedback Loop (MFL) is a small two-gene network where protein A regulates the transcription of protein B and the two proteins form a heterodimer. It has been found to be statistically over-represented in statistical analyses of gene and protein interaction databases and to lie at the core of several computer-generated genetic networks. Here, we propose and mathematically study a model of the MFL and show that, by itself, it can serve both as a bistable switch and as a clock (an oscillator) depending on kinetic parameters. The MFL phase diagram as well as a detailed description of the nonlinear oscillation regime are presented and some biological examples are discussed. The results emphasize the role of protein interactions in the function of genetic modules and the usefulness of modelling RNA dynamics explicitly.Comment: To be published in Physical Review

Draft Genome Sequence of the Principal Etiological Agent of Farmer?s Lung Disease, Saccharopolyspora rectivirgula

Saccharopolyspora rectivirgula is the main cause of farmer's lung disease. The development of recombinant antigens to standardize the serodiagnosis of the disease requires knowledge of the S. rectivirgula genome. We sequenced the genome of an environmental strain, S. rectivirgula DSM 43113. A total of 3,221 proteins were found to be encoded in a short 3.9-Mb genome

On the distortion of twin building lattices

We show that twin building lattices are undistorted in their ambient group; equivalently, the orbit map of the lattice to the product of the associated twin buildings is a quasi-isometric embedding. As a consequence, we provide an estimate of the quasi-flat rank of these lattices, which implies that there are infinitely many quasi-isometry classes of finitely presented simple groups. In an appendix, we describe how non-distortion of lattices is related to the integrability of the structural cocycle

Fermi Velocity Spectrum and Incipient Magnetism in TiBe2

We address the origin of the incipient magnetism in TiBe$_2$ through precise first principles calculations, which overestimate the ferromagnetic tendency and therefore require correction to account for spin fluctuations. TiBe$_2$ has sharp fine structure in its electronic density of states, with a van Hove singularity only 3 meV above the Fermi level. Similarly to the isovalent weak ferromagnet ZrZn$_2$, it is flat bands along the K-W-U lines of hexagonal face of the fcc Brillouin zone make the system prone to magnetism, and more so if electrons are added. We find that the Moriya $B$ coefficient (multiplying $\frac{\omega}{q}$ in the fluctuation susceptibility $\Delta \chi(q,\omega)$) is divergent when the velocity vanishes at a point on the Fermi surface, which is very close (3 meV) to occurring in TiBe$_2$. In exploring how the FM instability (the $q$=0 Stoner enhancement is $S\approx 60$) might be suppressed by fluctuations in TiBe$_2$, we calculate that the Moriya A coefficient (of $q^2$) is negative, so $q$=0 is not the primary instability. Explicit calculation of $\chi_o(q)$ shows that its maximum occurs at the X point $(1,0,0)\frac{2\pi}{a}$; TiBe$_2$ is thus an incipient {\it anti}ferromagnet rather than ferromagnet as has been supposed. We further show that simple temperature smearing of the peak accounts for most of the temperature dependence of the susceptibility, which previously had been attributed to local moments (via a Curie-Weiss fit), and that energy dependence of the density of states also strongly affects the magnetic field variation of $\chi$

Emergency department use by oldest-old patients from 2005 to 2010 in a Swiss university hospital.

BACKGROUND: Aging of the population in all western countries will challenge Emergency Departments (ED) as old patients visit these health services more frequently and present with special needs. The aim of this study is to describe the trend in ED visits by patients aged 85 years and over between 2005 and 2010, and to compare their service use to that of patients aged 65-84 years during this period and to investigate the evolution of these comparisons over time. METHODS: Data considered were all ED visits to the University of Lausanne Medical Center (CHUV), a tertiary Swiss teaching hospital, between 2005 and 2010 by patients aged 65 years and over (65+ years). ED visit characteristics were described according to age group and year. Incidence rates of ED visits and length of ED stay were calculated. RESULTS: Between 2005 and 2010, ED visits by patients aged 65 years and over increased by 26% overall, and by 46% among those aged 85 years and over (85+ years). Estimated ED visit incidence rate for persons aged 85+ years old was twice as high as for persons aged 65-84 years. Compared to patients aged 65-84 years, those aged 85+ years were more likely to be hospitalized and have a longer ED stay. This latter difference increased over time between 2005 and 2010. CONCLUSIONS: Oldest-old patients are increasingly using ED services. These services need to adapt their care delivery processes to meet the needs of a rising number of these complex, multimorbid and vulnerable patients

Validity of the FACIT-Sp to assess spiritual well-being in elderly patients

Among instruments measuring spiritual well-being, the Functional Assessment of Chronic Illness Therapy-Spiritual well-being (FACIT-Sp-12) is the most widely used instrument in research. It has been validated in patients suffering from cancer or HIV/AIDS, but has rarely been used in elderly patients. The objectives of this study were to determine the psychometric properties and suitability of the FACIT-Spto assess spiritual well-being in hospitalized elderly patients. This cross-sectional study uses a mixed method approach. Subjects were patients (N = 208), aged 65 years and older, consecutively admitted in post-acute rehabilitation. Psychometric properties of the FACITSp were investigated. The internal structure of the FACIT-Sp (factor structure and internal consistency) was assessed. Convergent validity of the FACIT-Sp was assessed using the Spiritual Distress Assessment Tool (SDAT), the question "Are you at peace?" and the Geriatric Depression Scale (GDS). Predictive validity was assessed using length of stay (LOS) and discharge destination. Understanding and interpretation of FACIT-Sp items were consecutively assessed in a sub-sample of 135 patients. Results show that FACIT-Sp scores ranged from 7 to 46 (mean 29.6 ± 7.8); 23.1% of the patients had high spiritual well-being. Cronbach's α was g ood ( 0.85). Item-to-total correlations were all significant (0.34 to 0.73). Principal component analyses performed with 2 or 3 factors were only moderately consistent with previous work. FACIT-Sp correlated with SDAT, "Are you at peace?" and GDS (Rho = −0.45, P < 0.001; 0.51, P < 0.001 and −0.38, P < 0.001). No association was found with LOS or discharge destination. Spontaneous comments about one or more FACIT-Sp items were made by 97/135 (71.9%). Specifically, items that address purpose and meaning in life were frequently found difficult to answer. Analyses suggest that the FACIT-Sp may underestimate spiritual well-being in older patients. In conclusion, despite having acceptable psychometric properties, the FACIT-Sp presents limitations for measurement of spiritual well-being in hospitalized elderly patients