Evidence for a Square-Square Vortex Lattice Transition in a High-T_{c} Cuprate Superconductor.

Using sound velocity and attenuation measurements in high magnetic fields, we identify a new transition in the vortex lattice state of La_{2-x}Sr_{x}CuO_{4}. The transition, observed in magnetic fields exceeding 35 T and temperatures far below zero field T_{c}, is detected in the compression modulus of the vortex lattice, at a doping level of x=p=0.17. Our theoretical analysis based on Eilenberger's theory of the vortex lattice shows that the transition corresponds to the long-sought 45° rotation of the square vortex lattice, predicted to occur in d-wave superconductors near a van Hove singularity.

Improving postpartum glucose screening after gestational diabetes mellitus: a cohort study to evaluate the multicentre IMPACT initiative.

AIMS: To evaluate a mobilization campaign, the IMPACT initiative, which included multidisciplinary meetings, provision of information and a systematic prescription of an oral glucose tolerance test to improve the rate of glucose screening in women with gestational diabetes mellitus in the four largest maternity units in our area, starting in March 2011. METHODS: We retrospectively compared the level of self-reported screening during the first 6 months postpartum of women who gave birth after having been diagnosed with gestational diabetes before (January 2009 to December 2010) and after the IMPACT campaign (April 2011 to February 2012). RESULTS: We included 961 women (589 in the period before and 372 in the period after the campaign was initiated) with a mean ± SD age of 33.2 ± 5.3 years and BMI of 27.8 ± 5.3 kg/m². Multivariate analysis, stratified using a propensity score in order to limit bias caused by imbalance between both periods, showed that the postpartum screening rate was higher after the campaign began (48.9 vs 33.3%, odds ratio 1.7, 95% CI 1.1-2.5; P = 0.019) and higher in women who received insulin treatment during pregnancy (odds ratio 2.3, 95% CI 1.5-3.6; P < 0.001), consumed fruit and vegetables daily (odds ratio 1.6, 95% CI 1.1-2.4; P = 0.035) and did not smoke (smoking vs non-smoking: odds ratio 0.3, 95% CI 0.1-0.7; P = 0.01). There was no interaction between the campaign effect and these particular conditions. The proportion of oral glucose tolerance tests performed in women who underwent screening increased from 6.3 to 33.0%. CONCLUSIONS: The IMPACT campaign increased postpartum screening, and the use the oral glucose tolerance test in particular. The effect of this initiative might be reinforced in women who are non-daily consumers of fruit and vegetables, smokers and those who do not receive insulin treatment during pregnancy.

Two-dimensional superconducting phase in LaTiO3/SrTiO3 heterostructures induced by high-mobility carrier doping.

In this Letter, we show that a superconducting two-dimensional electron gas is formed at the LaTiO3/SrTiO3 interface whose transition temperature can be modulated by a back-gate voltage. The gas consists of two types of carriers: a majority of low-mobility carriers always present, and a few high-mobility ones that can be injected by electrostatic doping. The calculation of the electron spatial distribution in the confinement potential shows that the high-mobility electrons responsible for superconductivity set at the edge of the gas whose extension can be tuned by the field effect.

de Haas-van Alphen study of the Fermi surfaces of superconducting LiFeP and LiFeAs.

We report a de Haas-van Alphen oscillation study of the 111 iron pnictide superconductors LiFeAs with T(c) ≈ 18 K and LiFeP with T(c) ≈ 5 K. We find that for both compounds the Fermi surface topology is in good agreement with density functional band-structure calculations and has almost nested electron and hole bands. The effective masses generally show significant enhancement, up to ~3 for LiFeP and ~5 for LiFeAs. However, one hole Fermi surface in LiFeP shows a very small enhancement, as compared with its other sheets. This difference probably results from k-dependent coupling to spin fluctuations and may be the origin of the different nodal and nodeless superconducting gap structures in LiFeP and LiFeAs, respectively.

Correction: Imatinib mesylate inhibits STAT5 phosphorylation in response to IL-7 and promotes T cell lymphopenia in chronic myelogenous leukemia patients.

A correction to this paper has been published and can be accessed via a link at the top of the paper.

High-field superconductivity in C-doped MgB2 bulk samples prepared by a rapid synthesis route.

The upper critical field sets the thermodynamic limit to superconductivity. A big gap is present between the upper-critical-field values measured in MgB2 polycrystalline bulk superconductors and those of thin films, where values as high as ~ 50 T have been achieved at 4.2 K. Filling this gap would unlock the potential of MgB2 for magnet applications. This work presents the results of an extensive experimental campaign on MgB2 bulk samples, which has been guided by a Design of Experiment. We modeled the dependence of the upper critical field on the main synthesis parameters and established a new record (~ 35 T at 4.2 K) preparing C-doped bulk samples by a non-conventional rapid-synthesis route. This value appears to be an upper boundary for the upper critical field in bulk samples. Structural disorder in films seems to act selectively on one of the two bands where superconductivity in MgB2 takes place: this enhances the upper critical field while reducing the critical temperature only by few Kelvins. On the other hand, the critical temperature in bulk samples decreases monotonically when structural disorder increases, and this imposes a limit to the maximum achievable upper critical field.

Calibration of the low-energy channel Thomson parabola of the LMJ-PETAL diagnostic SEPAGE with protons and carbon ions.

The SEPAGE diagnostic will detect charged particles (electrons, protons, and ions) accelerated in the interaction of the PETAL (PETawatt Aquitaine Laser) laser with its targets on the LMJ (Laser MegaJoule)-PETAL laser facility. SEPAGE will be equipped with a proton-radiography front detector and two Thomson parabolas (TP), corresponding to different ranges of the particle energy spectra: Above 0.1 MeV for electrons and protons in the low-energy channel, with a separation capability between protons and 12C6+ up to 20 MeV proton energy and above 8 MeV for the high-energy channel, with a separation capability between protons and 12C6+ up to 200 MeV proton kinetic energy. This paper presents the calibration of the SEPAGE's low-energy channel TP at the Tandem facility of Orsay (France) with proton beams between 3 and 22 MeV and carbon-ion beams from 5.8 to 84 MeV. The magnetic and electric fields' integrals were determined with an accuracy of 10-3 by combining the deflections measured at different energies with different target thicknesses and materials, providing different in-target energy losses of the beam particles and hence different detected energies for given beam energies.

Imatinib mesylate inhibits STAT5 phosphorylation in response to IL-7 and promotes T cell lymphopenia in chronic myelogenous leukemia patients.

Imatinib mesylate (IM) therapy has been shown to induce lower T cell counts in chronic myelogenous leukemia (CML) patients and an interference of IM with T cell receptor (TCR) signaling has been invoked to explain this observation. However, IL-7 and TCR signaling are both essential for lymphocyte survival. This study was undertaken to determine whether IM interferes with IL-7 or TCR signaling to explain lower T cell counts in patients. At diagnosis, CML patients have typically lower CD4+ counts in their blood, yet CD8+ counts are normal or even increased in some. Following the initiation of IM treatment, CD4+ counts were further diminished and CD8+ T lymphocytes were dramatically decreased. In vitro studies confirmed IM interference with TCR signaling through the inhibition of ERK phosphorylation and we showed a similar effect on IL-7 signaling and STAT5 phosphorylation (STAT5-p). Importantly however, using an in vivo mouse model, we demonstrated that IM impaired T cell survival through the inhibition of IL-7 and STAT5-p but not TCR signaling which remained unaffected during IM therapy. Thus, off-target inhibitory effects of IM on IL-7 and STAT5-p explain how T cell lymphopenia occurs in patients treated with IM.

Thermodynamic signatures of the field-induced states of graphite.

When a magnetic field confines the carriers of a Fermi sea to their lowest Landau level, electron-electron interactions are expected to play a significant role in determining the electronic ground state. Graphite is known to host a sequence of magnetic field-induced states driven by such interactions. Three decades after their discovery, thermodynamic signatures of these instabilities are still elusive. Here we report the detection of these transitions with sound velocity measurements. The evolution of elastic constant anomalies with temperature and magnetic field allows to draw a detailed phase diagram which shows that the ground state evolves in a sequence of thermodynamic phase transitions. Our analysis indicates that the electron-electron interaction is not the sole driving force of these transitions and that lattice degrees of freedom play an important role.

Description of a novel FR1 IgH PCR strategy and its comparison with three other strategies for the detection of clonality in B cell malignancies.

PCR amplification of IgH gene V-D-J junctional variability (IgH PCR) is increasingly replacing Southern analysis for the detection of clonal lymphoid populations in cases presenting diagnostic difficulties. In order to determine the most efficient strategy, we have compared three known methods, using consensus primers against the VH FR3 or FR2 (FR256) regions, or a mix of six primers against the FR1 region (FR1f), with a new approach using a consensus primer against FR1 (FR1c), never previously described for diagnostic purposes, on DNA from 89 monoclonal B-cell proliferations (16 ALL, 28 CLL/PLL, 15 myelomas, 30 NHL). We obtained a detection rate of 70% for FR3, 64% for FR1f and 77% and 78% for FR256 and FR1c, respectively. Polyclonal lymphocytes and mature T cell malignancies tested negative for all systems. Differences in the detection rate were related not only to the choice of VH primer but also the JH primer(s) used and the pathological subtype. All strategies led to adequate detection of leukaemic DNA, whereas the detection rate in myeloma varied between strategies from 47 to 80% and that of follicular lymphoma from 13 to 63%. The lowest detection rates were observed in follicular lymphoma and in mature CD5 negative proliferations, reflecting the probable correlation between somatic mutation and PCR false-negativity. The combined use of FR1c and FR256 allowed detection in at least one system of 92% of cases overall and at least 75% in all pathological subtypes, thus providing a simple, reliable and rapid non-radioactive system for the detection of B cell clonality.

Evidence for a small hole pocket in the Fermi surface of underdoped YBa2Cu3Oy.

In underdoped cuprate superconductors, the Fermi surface undergoes a reconstruction that produces a small electron pocket, but whether there is another, as yet, undetected portion to the Fermi surface is unknown. Establishing the complete topology of the Fermi surface is key to identifying the mechanism responsible for its reconstruction. Here we report evidence for a second Fermi pocket in underdoped YBa2Cu3Oy, detected as a small quantum oscillation frequency in the thermoelectric response and in the c-axis resistance. The field-angle dependence of the frequency shows that it is a distinct Fermi surface, and the normal-state thermopower requires it to be a hole pocket. A Fermi surface consisting of one electron pocket and two hole pockets with the measured areas and masses is consistent with a Fermi-surface reconstruction by the charge-density-wave order observed in YBa2Cu3Oy, provided other parts of the reconstructed Fermi surface are removed by a separate mechanism, possibly the pseudogap.

Factors associated with screening for glucose abnormalities after gestational diabetes mellitus: baseline cohort of the interventional IMPACT study.

INTRODUCTION: Although it is important to screen women who have had gestational diabetes mellitus (GDM) for abnormal post-partum glucose levels, such testing is rarely performed. The aim of this study was to use data from the first observational phase of the IMPACT study to determine rates of screening within 6 months of delivery in a multiethnic cohort, focusing in particular on the effects of social deprivation and the risk of future diabetes. PATIENTS AND METHODS: To investigate the frequency of post-partum screening, charts were analyzed, and all women attending four centres located in a deprived area who had had GDM between January 2009 and December 2010 were contacted by phone. The Evaluation of Precarity and Inequalities in Health Examination Centres (EPICES) deprivation index and Finnish Diabetes Risk Score (FINDRISK) questionnaire were also evaluated. RESULTS: Data were evaluable for 589 of the 719 women contacted (mean age: 33.4 ± 5.2 years; mean body mass index: 27.6 ± 5.4 kg/m(2)), and 196 (33.3%) reported having been screened. On multivariate analysis, factors associated with a lack of screening were smoking [odds ratio (OR): 0.42 (0.20-0.90), P<0.05], low consumption of fruit and vegetables [OR: 0.58 (0.39-0.82), P<0.01] and heavier offspring birth weight (P<0.05), although there were no differences in FINDRISK and EPICES scores between screened and unscreened women. CONCLUSION: One-third of women who had had GDM reported having been screened for dysglycaemia at 6 months post-partum. However, it is expected that the interventional phase of the IMPACT study will increase screening rates, especially in women with the risk factors associated with lower screening rates during this observational phase.

Direct measurement of the upper critical field in cuprate superconductors.

In the quest to increase the critical temperature Tc of cuprate superconductors, it is essential to identify the factors that limit the strength of superconductivity. The upper critical field Hc2 is a fundamental measure of that strength, yet there is no agreement on its magnitude and doping dependence in cuprate superconductors. Here we show that the thermal conductivity can be used to directly detect Hc2 in the cuprates YBa2Cu3Oy, YBa2Cu4O8 and Tl2Ba2CuO6+δ, allowing us to map out Hc2 across the doping phase diagram. It exhibits two peaks, each located at a critical point where the Fermi surface of YBa2Cu3Oy is known to undergo a transformation. Below the higher critical point, the condensation energy, obtained directly from Hc2, suffers a sudden 20-fold collapse. This reveals that phase competition-associated with Fermi-surface reconstruction and charge-density-wave order-is a key limiting factor in the superconductivity of cuprates.

de Haas-van Alphen oscillations in the underdoped high-temperature superconductor YBa2Cu3O6.5.

The de Haas-van Alphen effect was observed in the underdoped cuprate YBa2Cu3O6.5 via a torque technique in pulsed magnetic fields up to 59 T. Above a field of approximately 30 T the magnetization exhibits clear quantum oscillations with a single frequency of 540 T and a cyclotron mass of 1.76 times the free electron mass, in excellent agreement with previously observed Shubnikov-de Haas oscillations. The oscillations obey the standard Lifshitz-Kosevich formula of Fermi-liquid theory. This thermodynamic observation of quantum oscillations confirms the existence of a well-defined, closed, and coherent, Fermi surface in the pseudogap phase of cuprates.

Small Fermi surface pockets in underdoped high temperature superconductors: observation of Shubnikov-de Haas oscillations in YBa2Cu4O8.

We report the observation of Shubnikov-de Haas oscillations in the underdoped cuprate superconductor YBa2Cu4O8 (Y124). For fields aligned along the c axis, the frequency of the oscillations is 660+/-30 T, which corresponds to approximately 2.4% of the total area of the first Brillouin zone. The effective mass of the quasiparticles on this orbit is measured to be 2.7+/-0.3 times the free electron mass. Both the frequency and mass are comparable to those recently observed for ortho-II YBa2Cu3O6.5 (Y123-II). We show that although small Fermi surface pockets may be expected from band-structure calculations in Y123-II, no such pockets are predicted for Y124. Our results therefore imply that these small pockets are a generic feature of the copper oxide plane in underdoped cuprates.

Simultaneous SIL-TAL1 RT-PCR detection of all tal(d) deletions and identification of novel tal(d) variants.

Site-specific deletions of the 5' part of the TAL1 gene (tal(d)) are among the most frequent non-random genetic abnormalities in T-cell acute lymphoblastic leukaemia (T-ALL). They are usually detected by PCR from DNA with several primer pairs or by Southern blot analysis. Since tal(d) lead to expression of a SIL-TAL1 fusion transcript, irrespective of the genomic breakpoint, we have used a single monoplex RT-PCR reaction to screen 55 T-ALL patients at diagnosis. SIL-TAL1 transcripts were demonstrated in 12 (22%) cases, including 7/27 (26%) children <15 years of age, 2/8 (25%) adolescents and 2/17 (12%) adults aged >20 years. SIL-TAL1 RT-PCR was preferrable to tal(d) DNA PCR since it allowed the simultaneous detection of tal(d), tal(d2) and two previously undescribed tal(d) variants. SIL-TAL1 RT-PCR screening should therefore increase the detection rate of tal(d) by approximately 15-20%, with an at least comparable sensitivity to tal(d) genomic PCR, and represents a more practical and economic alternative to multiple DNA PCRs or Southern blotting when incorporated into molecular screening for multiple transcripts at diagnosis.

Detection of the chromosome 16 CBF beta-MYH11 fusion transcript in myelomonocytic leukemias.

Karyotypic detection of chromosomal 16 abnormalities classically associated with AML M4Eo can be difficult. Characterization of the two genes involved in the inv(16)(p13q22), CBF beta and MYH11, has allowed the detection of fusion transcripts by reverse-transcriptase polymerase chain reaction (RT-PCR). We have analyzed CBF beta-MYH11 fusion transcripts by RT-PCR in myelomonocytic leukemias, with or without eosinophilia, to determine whether their presence correlates with morphology. Fifty-three cases (11 AML M4Eo; 1 AML M4 with atypical abnormal eosinophils (AML M4 "Eo"); 29 AML M4; 8 AML M5; 3 CMML; and 1 AML M2 with eosinophilia) were analyzed. All 11 typical AML M4Eo were CBF beta-MYH11 positive. The single case of AML M4 with distinctive eosinophil abnormalities was negative by karyotype, RT-PCR and fluorescent in situ hybridization (FISH). Three of 29 (10%) AML M4 without abnormal eosinophils were CBF beta-MYH11 positive, 1 of which did not show any apparent chromosome 16 abnormalities by classical metaphase analysis (2 not tested). Both cases tested also showed MYH11 genomic rearrangement. None of the other leukemias were RT-PCR positive. Follow-up of three patient showed residual positivity in apparent complete remission. These data show that CBF beta-MYH11 fusion transcripts occur not only in the vast majority of typical AML M4Eo, but also in approximately 10% of AML M4 without eosinophilic abnormalities, a much higher incidence than the sporadic reports of chromosome 16 abnormalities in AML M4 would suggest. Taken together with the detection of CBF beta-MYH11 transcripts in the absence of apparent chromosome 16 abnormalities by classical banding techniques, these data show that additional screening by either RT-PCR or FISH should be performed in all AML M4, regardless of morphologic features, to allow accurate evaluation of the prognostic importance of this fusion transcript.

Heterogeneity of t(1;19)(q23;p13) acute leukaemias. French Haematological Cytology Group.

The t(1;19)(q23;p13) translocation occurs commonly in B-lineage ALL. Previous reports have demonstrated a predominance of cases with expression of cytoplasmic Ig mu (C mu+), and FAB L1/L2 phenotype, a poor prognosis and expression of a fusion transcript involving the E2A and PBX1 genes in C mu+ but not in C mu- cases. Of 38 patients with karyotypically proven t(1;19) (q23;p13) leukaemias, we extensively analysed 18 patients with acute leukaemia including 16 B-lineage ALLs, one T-ALL and one AML M4. The AML was associated with a classic E2A-PBX1 fusion transcript and may represent the human counterpart of the AMLs induced by E2A-PBX1 retroviral infection of murine marrow progenitors. The T-ALL was E2A-PBX1 negative and neither the E2A nor the LYL-1 genes, both situated at chromosome 19 p13, were rearranged. Of the 16 B-lineage ALLs, four had cytological features resembling an 'L3-like' phenotype classically associated with Burkitt's lymphoma, two at diagnosis and relapse and two exclusively at relapse. E2A-PBX1 fusion transcripts were detected by RT-PCR in all 13 C mu+ patients and in 2/3 C mu- cases. The 'L3-like' phenotype did not correlate with a particular stage of maturation arrest (one sIg+, one C mu+, one C mu-) or type of E2A-PBX1 transcript, but was associated in all cases with a trisomy 8. Translocation, rearrangement, amplification or over-expression of the c-myc gene was not observed in these cases, demonstrating that the apparent association with trisomy 8 is not due to deregulation of this gene. We therefore show that the E2A-PBX1 transcript, although occurring predominantly in C mu+ pre-B ALL, also occurs in C mu- early pre-B ALL, sIg+ B-ALL and even in AML. These results suggest that the stage of maturation arrest, and indirectly the prognosis, are not solely due to the type of fusion transcript associated with the t(1;19).