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Resume Introduction La thrombopenie induite par le 177Lu-DOTATATE est un de ses effets indesirables frequents. Sa persistance impactant la prise en charge ulterieure des patients, notamment lors de la progression de la maladie, la prevenir est un enjeu capital. Devant la penurie de connaissances sur le sujet, nous avons cherche a determiner l’existence de facteurs predisposants a la toxicite plaquettaire dans le bilan de suivi standard. Materiel et methodes Cette etude retrospective monocentrique a inclus 20 patients atteints de tumeurs neuroendocrines gastroenteropancreatiques. Differents parametres ont ete analyses, parmi lesquels le bilan biologique, le facteur d’envahissement osteomedullaire, le volume de la rate et l’activite estimee dans la moelle osseuse et la rate 24 h post-injection. Resultats Quatre patients ont presente une thrombopenie de grade 2 persistante a un an. Une chute du taux de plaquettes superieure a 30 % des la premiere cure ainsi qu’un facteur d’envahissement osteomedullaire superieur a 30 % etaient des facteurs de risque de thrombopenie severe, odds-ratio = ∞ (p = 0,0379) et odds-ratio = ∞ (p = 0,003) respectivement. Le taux initial de plaquettes, la fleche splenique et l’activite dans la rate a 24 h etaient correles au nadir plaquettaire r = 0,5459 (p = 0,0128) ; r = − 0,8105 (p Conclusion Cette etude suggere que la profondeur de la chute des plaquettes a la premiere cure ainsi que l’importance de l’envahissement osteomedullaire seraient des facteurs de risque de thrombopenie et evoque un role de la rate dans la physiopathogenie de la severite de cette thrombopenie.

Symmetry breaking in topological matter became, in the last decade, a key concept in condensed matter physics to unveil novel electronic states. In this work, we reveal that broken inversion symmetry and strong spin-orbit coupling in trigonal PtBi2 lead to a Weyl semimetal band structure, with unusually robust two-dimensional superconductivity in thin fims. Transport measurements show that high-quality PtBi2 crystals are three-dimensional superconductors (Tc≈600 mK) with an isotropic critical field (Bc≈50 mT). Remarkably, we evidence in a rather thick flake (60 nm), exfoliated from a macroscopic crystal, the two-dimensional nature of the superconducting state, with a critical temperature Tc≈370 mK and highly-anisotropic critical fields. Our results reveal a Berezinskii-Kosterlitz-Thouless transition with TBKT≈310 mK and with a broadening of Tc due to inhomogenities in the sample. Due to the very long superconducting coherence length ξ in PtBi2, the vortex-antivortex pairing mechanism can be studied in unusually-thick samples (at least five times thicker than for any other two-dimensional superconductor), making PtBi2 an ideal platform to study low dimensional superconductivity in a topological semimetal.

PtBi$_2$ is a polymorphic system with interesting electronic properties. Here we report optimized crystal growth and structural characterization of pyrite-type and trigonal modification of PtBi$_2$. Selected area electron diffraction, X-ray powder diffraction and further Rietveld refinement confirms that trigonal PtBi$_2$ crystallizes in non-centrosymmetric $P31m$ space group, pyrite-type PtBi$_2$ in $Pa\bar{3}$ space group. Series of Pt$_{1-x}$Rh$_x$Bi$_2$ samples was obtained for $x=0, 0.03, 0.35$ in the trigonal PtBi$_2$ structure. These Pt$_{1-x}$Rh$_x$Bi$_2$ compounds become superconducting where critical temperature increases from $T_c=600$ mK for $x=0$ up to $T_c=2.7$ K for $x=0.35$. Furthermore we calculate the electronic band structure, using the structure parameters obtained. The calculated density of states (DOS) shows a minimum for the stochiometric compound at the Fermi level. These findings warrant further research by broader array of experimental techniques, as well as the effect of the substitution on the non-trivial band structure.

International audience

Quantum coherent transport of spin-polarized carriers is observed on a very unusual large scale within epitaxial nanowires of GaMnAs, a diluted ferromagnetic semiconductor. From the analysis of the amplitude of strong universal conductance fluctuations, an effective phase coherence length of about 100 nm is inferred at T = 100 mK, which is one order of magnitude larger than in a granular 3d-metal ferromagnets. Together with the temperature and bias dependence of these reproducible fluctuations, their wire-length dependence is studied in single-domain sub-micron long nanowires with a perprendicular anisotropy. In particular, variations for two equivalent probe configurations are shown when the length becomes comparable to the actual phase coherence length. This result forecasts the possible observation of non-local voltage drops in GaMnAs nanostructures smaller than about 200 nm. Generally speaking, this research contributes to pave the way towards the realization of quantum spintronics devices.

This work provides new developments of the field of spin dynamics in mesoscopic systems. We first discuss, by a few examples, how environmental degrees of freedom affect tunneling and subsequent slow quantum relaxation of large molecule spins (such as Mn 12− AC) or rare-earth (RE) spins (such as Ho diluted in YLiF 4 ) showing two different facets of the spin bath model. The case of low molecule spins (V 15 ) is also considered. Then we discuss AC-susceptibility experiments performed on YLiF 4 :Ho 3+ allowing to clarify the roles played by the phonon and the spin baths on single-ion and two-ion electro-nuclear tunneling. In the last part, we extend these quantum dynamical studies to the case of Er diluted in CaWO 4 where the spin and phonon baths are weak enough to allow fast and coherent quantum dynamics with the observation of Rabi oscillations. The angular momentum and magnetic moment of Er, J =15/2and 9 μ B, are comparable to those of large molecule spins, implying easy manipulations of potential RE solid-state qubits.

Shubnikov-de-Haas oscillations were studied under high magnetic field in Bi$_2$Se$_3$ nanostructures grown by Chemical Vapor Transport, for different bulk carrier densities ranging from $3\times10^{19}\text{cm}^{-3}$ to $6\times10^{17}\text{cm}^{-3}$. The contribution of topological surface states to electrical transport can be identified and separated from bulk carriers and massive two-dimensional electron gas. Band bending is investigated, and a crossover from upward to downward band bending is found at low bulk density, as a result of a competition between bulk and interface doping. These results highlight the need to control electrical doping both in the bulk and at interfaces in order to study only topological surface states., 6 pages, 4 figures

In this work we report on the growth of single crystalline Bi2Se3 nanostructures (nanoribbons, nanoflakes, and nanowires) by catalyst-free decomposition sublimation in sealed silica ampules. The nanostructures directly grow on Si/SiO2 substrates by a vapor–solid growth mechanism and show high degree of crystallinity with dimensions of >10 μm in length and simultaneously

Tunneling of the total angular momentum of Ho 3+ in LiYF 4 (insulating matrix) is demonstrated. Due to strong hyperfine interactions, electronic angular momentum and nuclear spin tunnel simultaneously (two-body entanglement) and due to weak dipolar interactions, pairs of Ho 3+ ions also tunnel simultaneously (four-body entanglement). Similar results obtained with a metallic matrix (YRu 2 Si 2 ) prove the persistence of tunneling in the presence of free carriers.

After the first evidence for tunneling of the total angular momentum of Ho 3+ in YLiF 4 (insulating), where electronic and nuclear moments tunnel simultaneously (two-body entanglement), we show that pairs of Ho 3+ ions also tunnel simultaneously (four-body entanglement). Such co-tunneling transitions, mediated by weak dipolar interactions, are discussed in terms of a four-spin representation including the rare-earth nuclear spin. This study of the entanglement of pairs of distant Ho 3+ ions constitutes a first step to elucidate many-body quantum-spin relaxation. Finally, implications on the feasibility of two-spin qubits are discussed.

Mn-doped wurtzite GaN epilayers have been grown by nitrogen plasma-assisted molecular-beam epitaxy. Correlated SIMS, structural and magnetic measurements show that the incorporation of Mn strongly depends on the conditions of the growth. Hysteresis loops which persist at high temperature do not appear to be correlated to the presence of Mn. Samples with up to 2% Mn are purely substitutional Ga1 − xMnxN epilayers, and exhibit paramagnetic properties. At higher Mn contents, precipitates are formed which are identified as GaMn3N clusters by X-ray diffraction and absorption: this induces a decrease of the paramagnetic magnetisation. Samples co-doped with enough Mg exhibit a new feature: a ferromagnetic component is observed up to Tc ~ 175 K, which cannot be related to superparamagnetism of unresolved magnetic precipitates.

A systematic compositional and structural study of GaN:Mn epilayers grown by molecular beam epitaxy (MBE) was performed, with a special attention to the dependence on the growth conditions. The growth diagram related to the Ga/N flux ratio for GaN was modified by adding Mn flux. In particular, the stable Ga-bilayer coverage on the surface for the Ga-rich condition was reduced in the presence of Mn. The Mn incorporation in the epilayers was found to be strongly dependent on the Ga/N flux ratio. The X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) measurements revealed a clear contrast between the precipitation of a perovskite compound GaMn 3 N at Mn compositions higher than 1.7%, and the single phase of the wurtzite Ga 1-x Mn x N at lower Mn compositions. The single-phase epilayers (x < 1.7%) exhibited intrinsic ferromagnetic behaviors at room temperature.

We report on experimental evidence of the Berry phase accumulated by the charge carrier wave function in single-domain nanowires made from a (Ga,Mn)(As,P) diluted ferromagnetic semiconductor layer. Its signature on the mesoscopic transport measurements is revealed as unusual patterns in the magnetoconductance, that are clearly distinguished from the universal conductance fluctuations. We show that these patterns appear in a magnetic field region where the magnetization rotates coherently and are related to a change in the band-structure Berry phase as the magnetization direction changes. They should be thus considered as a band structure Berry phase fingerprint of the effective magnetic monopoles in the momentum space. We argue that this is an efficient method to vary the band structure in a controlled way and to probe it directly. Hence, (Ga,Mn)As appears to be a very interesting test bench for new concepts based on this geometrical phase., Comment: 7 pages, 6 figures

Quantum coherent transport of Dirac fermions in a mesoscopic nanowire of the 3D topological insulator Bi2Se3 is studied in the weak-disorder limit. At very low temperatures, many harmonics are evidenced in the Fourier transform of Aharonov-Bohm oscillations, revealing the long phase-coherence length of surface states. Remarkably, from their exponential temperature dependence, we infer an unusual 1/T power law for the phase coherence length. This decoherence is typical for quasi-ballistic fermions weakly coupled to the dynamics of their environment.

Context. Asteroid modeling efforts in the last decade resulted in a comprehensive dataset of almost 400 convex shape models and their rotation states. These efforts already provided deep insight into physical properties of main-belt asteroids or large collisional families. Going into finer detail (e.g., smaller collisional families, asteroids with sizes 20 km) requires knowledge of physical parameters of more objects. Aims. We aim to increase the number of asteroid shape models and rotation states. Such results provide important input for further studies, such as analysis of asteroid physical properties in different populations, including smaller collisional families, thermophysical modeling, and scaling shape models by disk-resolved images, or stellar occultation data. This provides bulk density estimates in combination with known masses, but also constrains theoretical collisional and evolutional models of the solar system. Methods. We use all available disk-integrated optical data (i.e., classical dense-in-time photometry obtained from public databases and through a large collaboration network as well as sparse-in-time individual measurements from a few sky surveys) as input for the convex inversion method, and derive 3D shape models of asteroids together with their rotation periods and orientations of rotation axes. The key ingredient is the support of more that 100 observers who submit their optical data to publicly available databases. Results. We present updated shape models for 36 asteroids, for which mass estimates are currently available in the literature, or for which masses will most likely be determined from their gravitational influence on smaller bodies whose orbital deflections will be observed by the ESA Gaia astrometric mission. Moreover, we also present new shape model determinations for 250 asteroids, including 13 Hungarias and three near-Earth asteroids. The shape model revisions and determinations were enabled by using additional optical data from recent apparitions for shape optimization. © 2016 ESO., J.H. greatly appreciates the CNES post-doctoral fellowship program. J.H. and M.D. were supported by the project under the contract 11-BS56-008 (SHOCKS) of the French Agence National de la Recherche (ANR), JD by grant GACR 15-04816S of the Czech Science Foundation, DO by the grant NCN 2012/S/ST9/00022 of Polish National Science Center, and A. Marciniak by grant 2014/13/D/ST9/01818 of Polish National Science Center.

We report the growth of Mn-doped wurtzite GaN epilayers by nitrogen plasma-assisted molecular beam epitaxy, with a systematic attention to the dependence on the growth conditions. The addition of Mn modifies the growth diagram related to the Ga/N flux ratio. In particular, the stable Ga-bilayer coverage on the growth surface for the Ga-rich condition is destabilized in the presence of Mn. Mn incorporation in the epilayers is found to strongly depend on the Ga/N flux ratio: it varies by two orders of magnitude between the Ga-rich and the N-rich growth conditions. X-ray diffraction measurements on epilayers grown in the stoichiometric condition reveal a clear contrast between the precipitation of perovskite GaMn3N clusters at Mn compositions higher than 1.7%, and the single phase of wurtzite Ga1−xMnxN at lower Mn compositions.

Low-temperature dynamics of mesoscopic magnetic moments of a 0.1% at Ho3+-doped LiYF4 single crystal is probed by ac-susceptibility measurements above T=1.75 K. In the temperature and frequency range studied (1.75 K⩽T⩽5 K,10 Hz⩽f⩽1500 Hz), the results clearly show that both thermally activated quantum tunneling of a nearly isolated magnetic moment and spin–spin cross relaxations occur. This interpretation is strongly supported by the calculated electro-nuclear Zeeman diagram either of a single ion or of a pair of diluted ions.

Mn has been incorporated in epilayers of the large-gap semiconductor GaN grown by molecular beam epitaxy using a nitrogen plasma cell. Detailed extended X-ray absorption fine structure (EXAFS) studies of a Ga0:98Mn0:02N epilayer confirm that the Mn atoms substitute the Ga atoms, with an increase by 2.7% of the distance to the nearest nitrogen atoms. Near edge spectroscopy results tend to indicate that the valence state of Mn is slightly higher than 3+, while EXAFS analysis suggests an electron transfer to the N neighbors.

Quantum coherent transport of surface states in a mesoscopic nanowire of the three-dimensional topological insulator Bi(2}Se(3) is studied in the weak-disorder limit. At very low temperatures, many harmonics are evidenced in the Fourier transform of Aharonov-Bohm oscillations, revealing the long phase coherence length of spin-chiral Dirac fermions. Remarkably, from their exponential temperature dependence, we infer an unusual 1/T power law for the phase coherence length L(φ)(T). This decoherence is typical for quasiballistic fermions weakly coupled to their environment.

The discovery of two-dimensional electron gases at the heterointerface between two insulating perovskite-type oxides, such as LaAlO(3) and SrTiO(3), provides opportunities for a new generation of all-oxide electronic devices. Key challenges remain for achieving interfacial electron mobilities much beyond the current value of approximately 1,000 cm(2) V(-1) s(-1) (at low temperatures). Here we create a new type of two-dimensional electron gas at the heterointerface between SrTiO(3) and a spinel γ-Al(2)O(3) epitaxial film with compatible oxygen ions sublattices. Electron mobilities more than one order of magnitude higher than those of hitherto-investigated perovskite-type interfaces are obtained. The spinel/perovskite two-dimensional electron gas, where the two-dimensional conduction character is revealed by quantum magnetoresistance oscillations, is found to result from interface-stabilized oxygen vacancies confined within a layer of 0.9 nm in proximity to the interface. Our findings pave the way for studies of mesoscopic physics with complex oxides and design of high-mobility all-oxide electronic devices.

Measurements of magneto-resistivity and magnetic susceptibility were performed on single crystals of superconducting Ba(Fe$_{0.9}$Co$_{0.1}$)$_{2}$As$_{2}$ close to the conditions of optimal doping. The high quality of the investigated samples allows us to reveal a dynamic scaling behaviour associated with a vortex-glass phase transition in the limit of weak degree of quenched disorder. Accordingly, the dissipative component of the ac susceptibility is well reproduced within the framework of Havriliak-Negami relaxation, assuming a critical power-law divergence for the characteristic correlation time $\tau$ of the vortex dynamics. Remarkably, the random disorder introduced by the Fe$_{1-x}$Co$_{x}$ chemical substitution is found to act on the vortices as a much weaker quenched disorder than previously reported for cuprate superconductors such as, e.g., Y$_{1-x}$Pr$_{x}$Ba$_{2}$Cu$_{3}$O$_{7-\delta}$., Comment: 10 pages, 8 figures

We report our experience of 15 cases of gastroschisis which occured between 1981 and 1993. All but one were diagnosed antenatally by ultrasound between 16 and 32 weeks of pregnancy. We made a termination of the pregnancy in 3 cases, for multiple malformations in 2 cases and one case of very early premature rupture of the membranes (PROM). When checked (11 cases), the karyotype was normal. We made a cesarean section in 11 cases: the indication was a complication for 6 (fetal distress, PROM, polyhydramnios, large dilatation of the gut). We noted growth retardation in 7 newborns and prematurity in 5 12 (mean gestational age of 36.8 weeks). The preoperative study of the gut noted 5 cases with intestinal damage and one case of complete necrosis of the gut. The global prognosis is not as good as usual, with a perinatal mortality of 41.6% ( 5 12 ). We discuss this latter point and examine the literature.

We retrospectively studied the outcome of pregnancy in 62 cases of absent end diastolic flow (AEDF) of umbilical artery Doppler flow velocity waveform. The history of pregnancies revealed that nearly all were of high risk. Many cases presented cerebral (65%) or uterine (55.5%) Doppler flow abnormalities, or both (38%). We noted 10 fetal deaths and decided 7 pregnancy terminations. Malformation and chromosomal defect rate was 16%. We noted 44 (71%) live-births, a very high rate of cesarean section (86%), prematurity (75%), small for gestational age (39%). Forty-five percent of the neonates had a 1-min Apgar score under 7, which dropped to 27% at 5 min. Neonate mortality rate was 6.9% and the total mortality rate was 34% (21/62). Morbidity was significant (7 cases with severe morbidity, 2 cases with chromosomal abnormality of poor prognosis). We compared different sub-groups with a view to looking for some prenatal factors which predict poor neonatal outcome in case of AEDF.

Strong hyperfine coupling in a 0.2% Holmium doped LiYF_4 single crystal induces staircaselike hysteresis loops of the magnetization at very low temperatures. The field sweep rate dependence of hysteresis loops allows the study of two different regimes in the magnetic relaxation of these weakly coupled magnetic moments. At slow field sweep rates, quantum tunneling of the magnetization occurs at avoided level crossings in the low-energy scheme of a single ion Ho^3+. At faster sweep rates, nonequilibrated spin-phonon and spin-spin transitions, mediated by weak dipolar interactions, lead to magnetization oscillations and additional steps., 4 figures, Conference proceeding: 1st Joint European Magnetic Symposia (JEMS01'), Grenoble (France), 28th August - 1st September, 2001

In 2009, the Critical Care Network of the American College of Chest Physicians (ACCP) in partnership with La Sociéte de Reanimation de Langue Française selected a panel of experts to characterize competence in critical care ultrasonography. The task force developed a consensus and made recommendations concerning the qualifications in ultrasonography. Experts have identified specific skills that intensivit should acquire, by setting a minimum standard for the realisation and control of ultrasound. Last year, we published in the present journal the results of this consensus conference concerning the "basic echocardiography" for intensivit. This year, we summarize here the results of the consensus conference and its conclusions on the assessment of advanced level skills to practice echocardiography in intensive care.

We present an original approach to fabricate single GaAs/AlGaAs core-shell nanowire with robust and reproducible transport properties. The core-shell structure is buried in an insulating GaAs overlayer and connected as grown in a two-probe setup using the highly doped growth substrate and a top diffused contact. The measured conductance shows a non-Ohmic behavior with temperature and voltage-bias dependences following power laws, as expected for a quasi one- dimensional system.

In critical care patients, microvascular alterations and perfusion heterogeneity play an important role in the persistence of cellular hypoxia despite a satisfactory functioning of the macrocirculation. Advance in the knowledge of microcirculatory pathophysiology, and its relation with the macrocirculation could be in the future a way to improve the outcome of critically ill patients. Moreover, the evolution of clinical practice towards microcirculation monitoring as a standard of care, with new therapeutic targets aimed to increase tissue perfusion, could be a revolution in critical care practice.

Microcirculation represents a complex system devoted to provide optimal tissue substrates and oxygen. Therefore, pathophysiological and technological knowledge developments tailored for capillary circulation analysis should generate major advances for critically ill patients' management. In the future, microcirculatory monitoring in several critical care situations will allow recognition of macro-microcirculatory decoupling, and, hopefully, it will promote the use of treatments aimed at preserving tissue oxygenation and substrate delivery.

International audience; Mesoscopic transport measurements reveal a large effective phase coherence length in epitaxial GaMnAs ferromagnets, contrary to usual 3d-metal ferromagnets. Universal conductance fluctuations of single nanowires are compared for epilayers with a tailored anisotropy. At large magnetic fields, quantum interferences are due to structural disorder only, and an unusual behavior related to hole-induced ferromagnetism is evidenced, for both quantum interferences and decoherence. At small magnetic fields, phase coherence is shown to persist down to zero field, even in presence of magnons, and an additional spin disorder contribution to quantum interferences is observed under domain walls nucleation.

Frequency and dc magnetic field dependences of dynamic susceptibility in diluted paramagnets $\mathrm{Li}\mathrm{Y}{\mathrm{F}}_{4}:{\mathrm{Ho}}^{3+}$ have been measured at liquid helium temperatures in ac and dc magnetic fields parallel to the symmetry axis of a tetragonal crystal lattice. Experimental data are analyzed in the framework of the microscopic theory of relaxation rates in the manifold of 24 electron-nuclear sublevels of the lowest non-Kramers doublet and the first excited singlet in the ${\mathrm{Ho}}^{3+}$ ground multiplet $^{5}I_{8}$ split by the crystal field of ${S}_{4}$ symmetry. The one-phonon transition probabilities were computed using electron-phonon coupling constants calculated in the framework of the exchange charge model and were checked by optical piezospectroscopic measurements. The specific features observed in field dependences of the in- and out-of-phase susceptibilities (humps and dips, respectively) at the crossings (anticrossings) of the electron-nuclear sublevels are well reproduced by simulations when the phonon bottleneck effect and the cross-spin relaxation are taken into account.

Current induced magnetization switching and resistance associated with domain walls pinned in nanoconstrictions have both been previously reported in (Ga,Mn)As based devices, but using very dissimilar experimental schemes and device geometries . Here we report on the simultaneous observation of both effects in a single nanodevice, which constitutes a significant step forward towards the eventual realization of spintronic devices which make use of domain walls to store, transport, and manipulate information.

We present and discuss the results of current induced magnetic switching experiments performed on pillar-shaped $(\mathrm{Ga},\mathrm{Mn})\mathrm{As}∕(\mathrm{In},\mathrm{Ga})\mathrm{As}∕(\mathrm{Ga},\mathrm{Mn})\mathrm{As}$ tunnel junctions. The sign of the switching currents confirms the opposite spin polarizations of the valence band holes and Mn atoms in (Ga,Mn)As. With respect to spin transfer experiments in purely metallic structures, the magnitude of the switching currents is smaller by two orders of magnitude, which can be explained mainly by the small magnetization of (Ga,Mn)As. A striking result is the observation of current induced magnetization switching at values of the bias voltage for which the magnetoresistance of the junction has dropped to almost zero. This raises interesting questions on the different role played by voltage-induced magnon excitations on magnetoresistance and current-induced magnetization switching.

We report the discovery of a super-giant tunneling anisotropic magnetoresistance in an epitaxially grown (Ga,Mn)As/GaAs/(Ga,Mn)As structure. The effect arises from a strong dependence of the electronic structure of ferromagnetic semiconductors on the magnetization orientation rather than from a parallel or antiparallel alignment of the contacts. The key novel spintronics features of this effect are: (i) both normal and inverted spin-valve like signals; (ii) a large non-hysteretic magnetoresistance for magnetic fields perpendicular to the interfaces; (iii) magnetization orientations for extremal resistance are, in general, not aligned with the magnetic easy and hard axis.(iv) Enormous amplification of the effect at low bias and temperatures. PACS numbers: 75.50.Pp, 85.75.Mm The emerging field of semiconductor based spintronics, which explores the spin and charge degrees of freedom on an equal footing, is expected to lead to novel information technologies that will overcome current key obstacles in the microelectronics roadmap [1]. A main component needed to realize the full potential of this technology is a device with similar behavior as current metal-based spin-valves [2], and with novel spintronics features unattainable in their metal counterparts. Previous attempts in this direction have yielded promising spin-valve results [3] apparently mimicking the functionality of the metal devices. However, our recent discovery of tunneling anisotropic magnetoresitance (TAMR) in a single (Ga,Mn)As layer structure [4] suggests that the moderate magnetoresistance (MR) effects observed so far in structures such as the one in Ref. 3 may originate from TAMR rather than the traditional metal tunneling MR (TMR). If this is the case, the device behavior should be much richer than for TMR, and could offer many new functionalities not possible in metal based devices. To investigate this hypothesis, we have fashioned a tunnel structure based on the ferromagnetic semiconductor (Ga,Mn)As. We report the existence of a huge TAMR effect exceeding 100 000% in these structures. The full layer structure of our device, shown in Fig. 1a, consists of a Ga0.94Mn0.06As (10 nm)/GaAs (2 nm) /Ga0.94Mn0.06As (100 nm) trilayer grown by low temperature molecular beam epitaxy (LT-MBE) on a semiinsulating GaAs substrate and an undoped GaAs buffer layer. The (Ga,Mn)As layers are intrinsically highly ptype due to the Mn and have metallic transport character. The undoped LT-GaAs layer on the other hand is insulating and forms an epitaxial tunnel barrier between the two ferromagnetic layers. The ferromagnetic transition temperature of the (Ga,Mn)As is � 65 K.

The large tunneling anisotropic magneto-resistance of a single $p^{++}$-(Ga,Mn)As/$n^{+}$-GaAs Zener-Esaki diode is evidenced in a perpendicular magnetic field over a large temperature and voltage range. Under an applied bias, the tunnel junction transparency is modified, allowing to continuously tune anisotropic transport properties between the tunneling and the ohmic regimes. Furthermore, an asymmetric bias-dependence of the anisotropic tunneling magneto-resistance is also observed: a reverse bias highlights the full (Ga,Mn)As valence band states contribution, whereas a forward bias only probes part of the density of states and reveals opposite contributions from two subbands., Comment: 11 pages, 3 figures

Wurtzite (Ga,Mn)N epilayers were grown by plasma‐assisted molecular beam epitaxy. Mn incorporation strongly depends on growth conditions. Infrared optical absorption shows absorption bands related to neutral Mn acceptor A0 at 1.412 eV and 1.43 eV. Magnetic circular dichroism spectroscopyat the band gap edge, in agreement with magnetization data, exhibits temperature and magnetic field dependence revealing paramagnetic properties of Mn‐doped GaN.

We report the discovery of a very large tunneling anisotropic magnetoresistance in an epitaxially grown (Ga,Mn)As/GaAs/(Ga,Mn)As structure. The key novel spintronics features of this effect are as follows: (i) both normal and inverted spin-valve-like signals; (ii) a large nonhysteretic magnetoresistance for magnetic fields perpendicular to the interfaces; (iii) magnetization orientations for extremal resistance are, in general, not aligned with the magnetic easy and hard axis; (iv) enormous amplification of the effect at low bias and temperatures.

We introduce a new class of spintronics devices in which a spin-valve like effect results from strong spin-orbit coupling in a single ferromagnetic layer rather than from injection and detection of a spin-polarized current by two coupled ferromagnets. The effect is observed in a normal-metal/insulator/ferromagnetic-semiconductor tunneling device. This behavior is caused by the interplay of the anisotropic density of states in (Ga,Mn)As with respect to the magnetization direction, and the two-step magnetization reversal process in this material., 4 pages, 4 figures, submitted to PRL

Recently reported room-temperature ferromagnetism in Mn-doped GaN thick layers is still debated, due to the possible formation of magnetic precipitates. We investigated the structural and magnetic properties of Mn-doped GaN epilayers with a Mn content as large as 18%. Below about 2%, only the pure diluted phase Ga1−xMnxN is obtained. Similarly to the x∼1.5% case discussed here, all measurements reveal a dominant paramagnetic component at low temperature, superimposed to a small hysteresis one which is not specific to our epilayers.

Staircaselike hysteresis loops of the magnetization of a LiY0.998Ho0.002F4 single crystal are observed at subkelvin temperatures and low field sweep rates. This behavior results from quantum dynamics at avoided level crossings of the energy spectrum of single Ho3+ ions in the presence of hyperfine interactions. Enhanced quantum relaxation in constant transverse fields allows the study of the relative magnitude of tunnel splittings. At faster sweep rates, nonequilibrated spin-phonon and spin-spin transitions, mediated by weak dipolar interactions, lead to magnetization oscillations and additional steps.

Longitudinal or transverse magnetic fields applied on a crystal of ${\mathrm{Mn}}_{12}$ acetate allows one to observe independent tunnel transitions between $m\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}S+p$ and $m\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}S\ensuremath{-}n\ensuremath{-}p$ ( $n\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}6--10$, $p\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0--2$ in longitudinal field and $n\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}p\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$ in transverse field). We observe a smooth transition (in longitudinal) from coherent ground-state to thermally activated tunneling. Furthermore, two ground-state relaxation regimes show a crossover between quantum spin relaxation far from equilibrium and near equilibrium, when the environment destroys multimolecule correlations. Finally, we stress that the complete Hamiltonian of ${\mathrm{Mn}}_{12}$ should contain odd spin operators of low order.

Because human papillomavirus (HPV) is sexually transmitted, as are pelvic inflammatory disease (PID) agents, the authors investigated whether cervical intra-epithelial neoplasia (CIN) are more frequent in women under treatment for PID. The study involved 298 patients hospitalized for PID, in whom CIN were investigated by smears and colposcopy. CIN were diagnosed in 42 patients, i.e. in 14% of patients: 21 low-grade CIN and 21 high-grade CIN, including one case of early-stage microinvasion. These figures are to be compared to the 0.5-4% of pre-cancerous lesions found in the general population. Screening smears are frequently inaccurate and direct colposcopy appeared preferable. No clinical study of this type has been published before, but certain authors have mentioned a high CIN incidence in patients with PID histories or followed up in sexually transmitted disease centers. These results show that CIN are more frequent in patients treated for PID; CIN should be investigated systematically in this population.

Post-partum ovarian vein thrombosis is often overlooked or mistaken for other complications such as endometritis. Color Doppler ultrasonography is a very good diagnostic method when properly indicated and correctly interpreted according to clinical data.This study reports ten cases that were retrospectively studied, during which color Doppler ultrasonography was used. The clinical signs and the results are reviewed.The lesions were clearly visualized in eight of the ten cases; one of the two failures resulted from a methodological fault (uninterpretable result); the other one was due to the lack of experience of the operator and nonrecognition of the clinical signs. Thrombosis appears as a hypoechogenic and tubular image. This type of examination is particularly indicated in the presence of certain clinical signs that were observed in our cases: fever and iliac pain are the main precursor signs, often associated with abdominal meteorism and slow digestive transit; provoked cul-de-sac pain during vaginal probing was the only constant sign, sometimes associated with painful swelling.

Objective: To investigate the efficacy of a selective intrapartum prophylaxy of group B streptococci (GBS) infection of the neonates. Study design: A prospective protocol of universal antepartum screening of GBS and selective intrapartum treatment from the 1st February 1994 to the 31st December 1995, on 2454 subsequent deliveries was designed. Our policy included: (1) antepartum screening as soon as possible after 28 weeks by a single vaginal and perianal sample for culture; (2) intrapartum recognition of one condition of high risk of fetal contamination during labor (these conditions included: a temperature of 38°C during labor, rupture of membranes for more than 12 h or prolonged labor for more than 12 h with rupture of membranes, prematurity, twins, maternal diabetes, previous pregnancy with GBS infection of the neonate); and (3) intrapartum anti-bioprophylaxy (amoxicillin) for women with positive screening during pregnancy and one condition of high risk of fetal contamination during labor. We studied the outcome of neonates during this period to look for immediate GBS severe infection of the neonates in the form of bacteraemia or meningitis and compared the results with the rate of neonatal infection before this protocol (4,51000 live births in 1993). Results: We noted that 11% of pregnant women were carriers, 25% of which led to antibiotic chemoprophylaxis during the labor. We noticed four cases of neonatal bacteraemia of GBS. One case arose from the group of carriers (but no condition of risk of fetal contamination during the labor and no chemoprophylaxy). The three other cases were from women with a negative antepartum screening. There was no case of meningitis and all four babies were in good health at day 10 of life. Comparing with results prior to the study, we noticed that the rate of neonatal bacteraemia dropped from 4.5 to 1.6 per 1000 livebirths (P < 0.0001). Conclusion: This protocol of intrapartum anti-bioprophylaxy significantly decreases the rate of GBS neonatal sepsis. We propose to improve the efficacy of this prevention program, especially with regard to the method of antepartum screening of pregnant women colonized with GBS.

To demonstrate that women treated for PID constitute a population with a specially high incidence of cervical intraepithelial neoplasia (CIN) and who should be screened for CIN.Retrospective, non-comparative study of 260 patients treated for PID in the Gynecology-Obstetrics Department of Hôtel-Dieu hospital in Rennes (France) from December 1st, 1989 to May 31st, 1996. CIN screening was performed by smear tests and colposcopy.Cervical lesions were detected in 39 patients (15%): five CIN 3 (including one early-stage microinvasion), twelve CIN 2 and 22 CIN 1 and/or condylomas, i.e., 6.5% high grade and 8.5% low grade lesions. Colposcopy in this case proved to be more effective than smears for screening.According to epidemiological studies, sexual behavior is a major risk factor of CIN, due to the role played by sexually transmissible human papillomavirus in their pathogenesis. Because the main risk factor of PID is sexual activity, it is likely that CIN are more frequent in women with PID. Our study clearly established that fact because the prevalence of CIN in the general population is only 0.5 to 4% according to literature reports.We are in favor of CIN screening in women treated for PID, and in our view colposcopy is the preferred method.

To assess the means to diagnose grade 3 cervical intraepithelial neoplasia (CIN 3) during pregnancy, with special consideration to the risk of overlooking invasive lesions.a retrospective study on 16 cases of CIN 3 over 4 years and a literature review.Smear tests were indicative of low-grade lesions in 8 cases. Colposcopy always was suggestive and accompanied by biopsy. No conisations were performed during pregnancy but one was performed after delivery in 15 of 16 cases. After delivery, comparing conisation results with those of recent biopsies revealed that some lesions were less severe and others more severe than during pregnancy. So, a CIN 3 and a microinvasive carcinoma observed during pregnancy changed into CIN 2 and CIN 3, respectively, after delivery. In contrast, two pregnancy CIN 2 were seen as CIN 3 in post-partum and three CIN 3 as MIC. Such variations have been described in the literature and have several causes. In particular, improvements may sometimes reach "normalisation" in post partum although, recurrences remain possible.when the smear tests performed during pregnancy are indicative of cervical intra-epithalial lesions, whatever the severity, colposcopy with biopsies are mandatory. If a CIN 3 is detected, early MIC should be removed, which may require specific treatment according to the invasive degree. Colposcopy with guided biopsies is a safe and reliable diagnostic means. After delivery, the cervix should always be reexamined, preferably by conisation, even if smears or colposcopy were normal.

Seventeen cases of mixed Muller tumours (tumours of the uterus with malignant epithelial and mesenchymal components) are presented. These recently described tumours are rare and occur in menopaused women. Bloody discharge is the usual clinical manifestation, together with an increase of the volume of the uterus. Pathology examination of the surgical specimen is required for diagnosis using immunolabeling to distinguish between homologous tumours (the sarcomatous component occurs in the primary mesenchyma) and heterologous tumours (the mesenchymatous component results from a metastasis). Prognosis, usually poor, depends on the stage of the tumour. Overall survival at 5 years is about 30%. Survival in early stage I and state II tumours is no greater than 50% at 5 years. Treatment is based on radiosurgical techniques in less advanced tumours and requires radiochemotherapy in more advanced stage tumours. Recurrence is usually seen within 2 years, involving the pelvis alone in 10% of the cases and metastasis in most of the others. Because of their rapid development and poor prognosis, these tumours should be identified separately as a separate entity within a larger group of mixed mesodermic tumours.

to estimate the social and economical point of view of the practice of in vitro fertilization (IVF) in Brittany in 1993.we made a prospective study of 152 cases of IVF. We studied the medical history of sterility of the patients, treatments during IVF, hormonal and ultrasound monitoring, oocytes retrieval and embryo transfer, and the screening until beta-hCG1,000 UI or evidence of pregnancy with ultrasound scan. After analysing results of IVF, we studied the cost of all these steps, including hospitalization, transports and stoppage.we estimated the mean price of one IVF cycle at 11,084 francs. We analysed the portion of each step in the total cost and discussed with the view of literature.the cost of IVF seems reasonable in this context.