Dimensional Crossover in a Charge Density Wave Material Probed by Angle-Resolved Photoemission Spectroscopy.

High-resolution angle-resolved photoemission spectroscopy data reveal evidence of a crossover from one-dimensional (1D) to three-dimensional (3D) behavior in the prototypical charge density wave (CDW) material NbSe_{3}. In the low-temperature 3D regime, gaps in the electronic structure are observed due to two incommensurate CDWs, in agreement with x-ray diffraction and electronic-structure calculations. At higher temperatures we observe a spectral weight depletion that approaches the power-law behavior expected in one dimension. From the warping of the quasi-1D Fermi surface at low temperatures, we extract the energy scale of the dimensional crossover. This is corroborated by a detailed analysis of the density of states, which reveals a change in dimensional behavior dependent on binding energy. Our results offer an important insight into the dimensionality of excitations in quasi-1D materials.

Collapse of the Mott Gap and Emergence of a Nodal Liquid in Lightly Doped Sr(2)IrO(4).

We report angle resolved photoemission experiments on the electron doped Heisenberg antiferromagnet (Sr(1-x)La(x))(2)IrO(4). For a doping level of x=0.05, we find an unusual metallic state with coherent nodal excitations and an antinodal pseudogap bearing strong similarities with underdoped cuprates. This state emerges from a rapid collapse of the Mott gap with doping resulting in a large underlying Fermi surface that is backfolded by a (π,π) reciprocal lattice vector which we attribute to the intrinsic structural distortion of Sr(2)IrO(4).

SIMMEON-Prep study: SIMulation of Medication Errors in ONcology: prevention of antineoplastic preparation errors.

WHAT IS KNOWN AND OBJECTIVE: Medication errors (ME) in oncology are known to cause serious iatrogenic complications. However, MEs still occur at each step in the anticancer chemotherapy process, particularly when injections are prepared in the hospital pharmacy. This study assessed whether a ME simulation program would help prevent ME-associated iatrogenic complications. METHODS: The 5-month prospective study, consisting of three phases, was undertaken in the centralized pharmaceutical unit of a university hospital of Lyon, France. During the first simulation phase, 25 instruction sheets each containing one simulated error were inserted among various instruction sheets issued to blinded technicians. The second phase consisted of activity aimed at raising pharmacy technicians' awareness of risk of medication errors associated with antineoplastic drugs. The third phase consisted of re-enacting the error simulation process 3 months after the awareness campaign. The rate and severity of undetected medication errors were measured during the two simulation (first and third) phases. The potential seriousness of the ME was assessed using the NCC MERP(®) index. RESULTS AND DISCUSSION: The rate of undetected medication errors decreased from 12 in the first simulation phase (48%) to five in the second simulation phase (20%, P = 0.04). The number of potential deaths due to administration of a faulty preparation decreased from three to zero. Awareness of iatrogenic risk through error simulation allowed pharmacy technicians to improve their ability to identify errors. WHAT IS NEW AND CONCLUSION: This study is the first demonstration of the successful application of a simulation-based learning tool for reducing errors in the preparation of injectable anticancer drugs. Such a program should form part of the continuous quality improvement of risk management strategies for cancer patients.

Optical response of Sr2RuO4 reveals universal fermi-liquid scaling and quasiparticles beyond Landau theory.

We report optical measurements demonstrating that the low-energy relaxation rate (1/τ) of the conduction electrons in Sr(2)RuO(4) obeys scaling relations for its frequency (ω) and temperature (T) dependence in accordance with Fermi-liquid theory. In the thermal relaxation regime, 1/τ ∝ (hω)(2)+(pπk(B)T)(2) with p = 2, and ω/T scaling applies. Many-body electronic structure calculations using dynamical mean-field theory confirm the low-energy Fermi-liquid scaling and provide quantitative understanding of the deviations from Fermi-liquid behavior at higher energy and temperature. The excess optical spectral weight in this regime provides evidence for strongly dispersing "resilient" quasiparticle excitations above the Fermi energy.

[Suicide attempts of 48 children aged 6-12 years]. / Tentatives de suicide chez 48 enfants âgés de 6 à 12ans.

AIM: Research is limited on suicide attempts in children under 13 years of age. The objective of this study was to provide an in-depth description of this population. MATERIALS AND METHODS: The present study is both retrospective and descriptive. Data were collected retrospectively from a file containing the causes for hospitalization of each child admitted into the Department of Child Psychiatry at the hôpital Femme-Mère-Enfant (hospices civils de Lyon). We included all patients under 13 years of age who were hospitalized for a suicide attempt between 2008 and 2011. The methods used to collect the medical records consisted in using a form made up of four major parts: suicide attempts, social environment, medical history, and therapy. RESULTS: The 26 girls and 22 boys included had a mean age of 11.52 years. The boys were younger than the girls (P=0.047) and their parents were usually separated (P=0.034). The boys used more violent means to commit suicide in comparison to the girls (P=0.048). On average, children using violent means were younger (P=0.013). Boys underwent more psychotherapy (P=0.027) and were prescribed more psychotropic medication in comparison to girls (P=0.051). Adjustment disorders (37.5%) and depression (27%) were the two main diagnoses for hospitalization. They were hospitalized on average (±standard deviation) 9.6 days (±10 days). Psychotherapy was organized when leaving the hospital (98%) with legal measures (8.3%), change of residence (12.5%), and prescription of psychotropic drugs (37.5%). None had physical complications. DISCUSSION: In children under 13 years of age, attempted suicide was more frequent in girls than boys. However, the sample included 18 girls and nine boys who were 12 years old (sex ratio of 12-year-olds, 0.5). There were more boys (16 boys/eight girls) in the children under 12 (sex ratio of 8- to 11-year-olds, 1.6). Children under 11 used more violent means (P=0.01). The literature also reports that more violent means lead to a greater risk of death by suicide. Consequently, suicidal behavior in children under 11 years of age is closer to a behavior of a person who has committed suicide than an adolescent attempting suicide. As a result of the sex ratio and non-violent means, 12-year-old children's behavior can be considered like that of adolescents. One factor that could explain children's attempted suicide is family cohesion. The children in this study were most often from broken families and had a difficult relationship with their parents. From 1981 to 1985, more than 50% of children who consulted for their first suicide attempt were not hospitalized. Now hospitalization is recommended for all children who consult for attempted suicide. They are hospitalized on average 8.9-9 days. Individual psychotherapy is systematic. The main difference between the treatments for adolescents and children is the importance of the social worker who will require legal measures or changing residences when necessary. CONCLUSION: The sex ratio in 6- to 12-year-olds attempting suicide is higher than the sex ratio in adolescents attempting suicides. Insecure attachment was found in all families in this sample. This population is particularly at risk knowing that in adulthood, the risk of death by suicide is higher when there is a background of attempted suicide by violent methods. These children should always be hospitalized for a psychological and socioenvironmental evaluation.

Two-dimensional Fermi liquid with attractive interactions.

We realize and study an attractively interacting two-dimensional Fermi liquid. Using momentum-resolved photoemission spectroscopy, we measure the self-energy, determine the contact parameter of the short-range interaction potential, and find their dependence on the interaction strength. We successfully compare the measurements to a theoretical analysis, properly taking into account the finite temperature, harmonic trap, and the averaging over several two-dimensional gases with different peak densities.

First direct observation of the Van Hove singularity in the tunnelling spectra of cuprates.

In two-dimensional (2D) lattices, the electronic levels are unevenly spaced, and the density of states (DOS) displays a logarithmic divergence known as the Van Hove singularity (VHS). This is the case in particular for the layered cuprate superconductors. The scanning tunnelling microscope (STM) probes the DOS, and is therefore the ideal tool to observe the VHS. No STM study of cuprate superconductors has reported such an observation so far giving rise to a debate about the possibility of observing directly the normal state DOS in the tunnelling spectra. In this study, we show for the first time that the VHS is unambiguously observed in STM measurements performed on the cuprate Bi2Sr2CuO(6+δ) (Bi-2201). Beside closing the debate, our analysis proves the presence of the pseudogap in the overdoped side of the phase diagram of Bi-2201 and discredits the scenario of the pseudogap phase crossing the superconducting dome.

Multiband superconductivity in the Chevrel phases SnMo6S8 and PbMo6S8.

Sub-Kelvin scanning tunneling spectroscopy in the Chevrel phases SnMo6S8 and PbMo6S8 reveals two distinct superconducting gaps with Δ1=3 meV, Δ2∼1.0 meV and Δ1=3.1 meV, Δ2∼1.4 meV, respectively. The gap distribution is strongly anisotropic, with Δ2 predominantly seen when scanning across unit-cell steps on the (001) sample surface. The spectra are well fitted by an anisotropic two-band BCS s-wave gap function. Our spectroscopic data are confirmed by electronic heat capacity measurements, which also provide evidence for a twin-gap scenario.

Imaging the essential role of spin fluctuations in high-T(c) superconductivity.

We have used scanning tunneling spectroscopy to investigate short-length electronic correlations in three-layer Bi2Sr2Ca2Cu3O(10+delta) (Bi-2223). We show that the superconducting gap and the energy Omega(dip), defined as the difference between the dip minimum and the gap, are both modulated in space following the lattice superstructure and are locally anticorrelated. Based on fits of our data to a microscopic strong-coupling model, we show that Omega(dip) is an accurate measure of the collective-mode energy in Bi-2223. We conclude that the collective mode responsible for the dip is a local excitation with a doping dependent energy and is most likely the (pi, pi) spin resonance.

Scanning tunneling spectroscopy in the superconducting state and vortex cores of the beta-pyrochlore KOs2O6.

We performed the first scanning tunneling spectroscopy measurements on the pyrochlore superconductor KOs2O6 (T(c)=9.6 K) in both zero magnetic field and the vortex state at several temperatures above 1.95 K. This material presents atomically flat surfaces, yielding spatially homogeneous spectra which reveal fully gapped superconductivity with a gap anisotropy of 30%. Measurements performed at fields of 2 and 6 T display a hexagonal Abrikosov flux line lattice. From the shape of the vortex cores, we extract a coherence length of 31-40 A, in agreement with the value derived from the upper critical field H(c2). We observe a reduction in size of the vortex cores (and hence the coherence length) with increasing field which is consistent with the unexpectedly high and unsaturated upper critical field reported.

Breakup of the Fermi surface near the mott transition in low-dimensional systems.

We investigate the Mott transition in weakly coupled one-dimensional (1D) fermionic chains. Using a generalization of dynamical mean field theory, we show that the Mott gap is suppressed at some critical hopping t{ perpendicular}{c2}. The transition from the 1D insulator to a 2D metal proceeds through an intermediate phase where the Fermi surface is broken into electron and hole pockets. The quasiparticle spectral weight is strongly anisotropic along the Fermi surface, both in the intermediate and metallic phases. We argue that such pockets would look like "arcs" in photoemission experiments.

Interferometric coupling of the Keck telescopes with single-mode fibers.

Here we report successful interferometric coupling of two large telescopes with single-mode fibers. Interference fringes were obtained in the 2- to 2.3-micrometer wavelength range on the star 107 Herculis by using the two Keck 10-meter telescopes, each feeding their common interferometric focus with 300 meters of single-mode fibers. This experiment demonstrates the potential of fibers for future kilometric arrays of telescopes and is the first step toward the 'OHANA (Optical Hawaiian Array for Nanoradian Astronomy) interferometer at the Mauna Kea observatory in Hawaii. It opens the way to sensitive optical imagers with resolutions below 1 milli-arc second. Our experimental setup can be directly extended to large telescopes separated by many hundreds of meters.

An MLH1 haplotype is over-represented on chromosomes carrying an HNPCC predisposing mutation in MLH1.

BACKGROUND: The mismatch repair gene, MLH1, appears to occur as two main haplotypes at least in white populations. These are referred to as A and G types with reference to the A/G polymorphism at IVS14-19. On the basis of preliminary experimental data, we hypothesised that deviations from the expected frequency of these two haplotypes could exist in carriers of disease associated MLH1 germline mutations. METHODS: We assembled a series (n=119) of germline MLH1 mutation carriers in whom phase between the haplotype and the mutation had been conclusively established. Controls, without cancer, were obtained from each contributing centre. Cases and controls were genotyped for the polymorphism in IVS14. RESULTS: Overall, 66 of 119 MLH1 mutations occurred on a G haplotype (55.5%), compared with 315 G haplotypes on 804 control chromosomes (39.2%, p=0.001). The odds ratio (OR) of a mutation occurring on a G rather than an A haplotype was 1.93 (95% CI 1.29 to 2.91). When we compared the haplotype frequencies in mutation bearing chromosomes carried by people of different nationalities with those seen in pooled controls, all groups showed a ratio of A/G haplotypes that was skewed towards G, except the Dutch group. On further analysis of the type of each mutation, it was notable that, compared with control frequencies, deletion and substitution mutations were preferentially represented on the G haplotype (p=0.003 and 0.005, respectively). CONCLUSION: We have found that disease associated mutations in MLH1 appear to occur more often on one of only two known ancient haplotypes. The underlying reason for this observation is obscure, but it is tempting to suggest a possible role of either distant regulatory sequences or of chromatin structure influencing access to DNA sequence. Alternatively, differential behaviour of otherwise similar haplotypes should be considered as prime areas for further study.

Molecular and clinical characteristics in 32 families affected with familial adenomatous polyposis.

Germ-line mutations in the 5' half of the Adenomatous Polyposis Coli (APC) gene are found in about 80% of the patients affected with familial adenomatous polyposis (FAP). The vast majority of these are nonsense or frameshift mutations which result in the loss of the carboxyl terminus of the APC protein. Using an in vivo assay in yeast, we have identified pathogenic germ-line mutations in 26 of 32 (81%) unrelated Swiss families affected with FAP. Nine mutations were novel and eight families were shown to harbor two recurrent mutations. Correlations were attempted between the location of APC germ-line mutations and clinical manifestations of the disease.

Density of states in high- T(c) superconductor vortices.

We calculated the electronic structure of a vortex in a pseudogapped superconductor within a model featuring strong correlations. With increasing strength of the correlations, the BCS core states are suppressed and the spectra inside and outside the core become similar. If the correlations are short range, we find new core states in agreement with the observations in YBa2Cu3O7-delta and Bi2Sr2CaCu2O8+delta. Our results point to a common phenomenology for these two systems and indicate that normal-state correlations survive below T(c) without taking part in the overall phase coherence.

Purification, characterization, DNA sequence and cloning of a pimeloyl-CoA synthetase from Pseudomonas mendocina 35.

A pimeloyl-CoA synthetase from Pseudomonas mendocina 35 was purified and characterized, the DNA sequence determined, and the gene cloned into Escherichia coli to yield an active enzyme. The purified enzyme had a pH optimum of approximately 8.0, Km values of 0.49 mM for pimelic acid, 0.18 mM for CoA and 0.72 mM for ATP, a subunit Mr of approximately 80000 as determined by SDS/PAGE, and was found to be a tetramer by gel-filtration chromatography. The specific activity of the purified enzyme was 77.3 units/mg of protein. The enzyme was not absolutely specific for pimelic acid. The relative activity for adipic acid (C6) was 72% and for azaleic acid (C9) was 18% of that for pimelic acid (C7). The N-terminal amino acid was blocked to amino acid sequencing, but controlled proteolysis resulted in three peptide fragments for which amino acid sequences were obtained. An oligonucleotide gene probe corresponding to one of the amino acid sequences was synthesized and used to isolate the gene (pauA, pimelic acid-utilizing A) coding for pimeloyl-CoA synthetase. The pauA gene, which codes for a protein with a theoretical Mr of 74643, was then sequenced. The deduced amino acid sequence of the enzyme showed similarity to hypothetical proteins from Archaeoglobus fulgidus, Methanococcus jannaschii, Pyrococcus horikoshii, E. coli and Streptomyces coelicolor, and some limited similarity to microbial succinyl-CoA synthetases. The similarity with the protein from A. fulgidus was especially strong, thus indicating a function for this unidentified protein. The pauA gene was cloned into E. coli, where it was expressed and resulted in an active enzyme.

TNF production and hypertrophic scarring.

The percentage of TNF alpha- and beta-positive cells was analyzed in hypertrophic scar (N = 13), normotrophic scar (N = 7), and normal skin (N = 6) biopsies using monoclonal antibodies and immunoperoxidase staining of cryostat tissue sections. Samples were first characterized for infiltrating cells. In hypertrophic samples there was a significant increase in activated infiltrating cells, capable of producing TNF beta and IL-1 beta. In contrast, the percentage of TNF alpha-positive cells was significantly lower than that detected in normotrophic scars. In fact, in hypertrophic scar samples a positive staining with anti-TNF alpha mAb was restricted to 8% of tissue-infiltrating cells compared to 35.4% of the cells present in normotrophic scars; 12% of infiltrating cells were stained in normal skin sections. These results suggest that TNF alpha may be important for normal wound healing and that hypertrophic scarring might be partially a consequence of a low amount of TNF alpha.

Free testosterone levels in plasma and saliva as determined by a direct solid-phase radioimmunoassay: a critical evaluation.

We compared unbound (free) testosterone radioimmunoassay concentrations in plasma and saliva from men, using a direct radioimmunoassay kit involving a ligand analog of testosterone as tracer. The assay failed to reveal detectable testosterone concentrations in saliva. In plasma the free testosterone levels were about 4 times lower than those obtained by calculation or ultrafiltration methods. Moreover, unexpected similar free testosterone levels were obtained in samples comparable in their total testosterone content but distinct in their steroid binding protein content (buffered testosterone dilutions). We suspect that free testosterone levels determined with this direct radioimmunoassay probably do not reflect the true free testosterone values and conclude that their significance remains to be established.