Very high frequency spectroscopy and tuning of a single-cooper-pair transistor with an on-chip generator

A single-Cooper-pair transistor (SCPT) is coupled capacitively to a voltage biased Josephson junction, used as a high-frequency generator. Thanks to the high energy of photons generated by the Josephson junction, transitions between energy levels, not limited to the first two levels, were induced and the effect of this irradiation on the dc Josephson current of the SCPT was measured. The phase and gate bias dependence of energy levels of the SCPT at high energy is probed. Because the energies of photons can be higher than the superconducting gap we can induce not only transfer of Cooper pairs but also transfer of quasiparticles through the island of the SCPT, thus controlling the poisoning of the SCPT. This can both decrease and increase the average Josephson energy of the SCPT: its supercurrent is then controlled by high-frequency irradiation.

Universal conductance fluctuations in epitaxial GaMnAs ferromagnets: dephasing by structural and spin disorder

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.

Apc mutation induces resistance of colonic cells to lipoperoxide-triggered apoptosis induced by faecal water from haem-fed rats

Recent epidemiological studies suggest that high meat intake is associated with promotion of colon cancer linked with haem-iron intake. We previously reported that dietary haem, in the form of either haemoglobin or meat, promotes precancerous lesions in the colon of rats given a low-calcium diet. The mechanism of promotion by haem is not known, but is associated with increased lipid peroxidation in faecal water and strong cytotoxic activity of faecal water on a cancerous mouse colonic epithelial cell line. To better understand the involvement of faecal water components of haem-fed rats in colon-cancer promotion, we explored the effect of faecal water on normal [adenomatous polyposis coli (Apc)+/+] or premalignant cells (Apc-/+). Further, we tested if this effect was correlated to lipoperoxidation and 4-hydroxynonenal (HNE). We show here for the first time that heterozygote Apc mutation represents a strong selective advantage, via resistance to apoptosis induction (caspase 3 pathway), for colonic cells exposed to a haem-iron-induced lipoperoxidation. The fact that HNE treatment of the cells provoked the same effects as the faecal water of rats fed the haem-rich diet suggests that this compound triggers apoptosis in those cells. We propose that this mechanism could be involved in the promotion of colon carcinogenesis by haem in vivo.

Improved search for nu(mu) --> nu(e) oscillation in a long-baseline accelerator experiment

We performed an improved search for nu(mu) --> nu(e) oscillation with the KEK to Kamioka (K2K) long-baseline neutrino oscillation experiment, using the full data sample of 9.2 x 10(19) protons on target. No evidence for a nu(e) appearance signal was found, and we set bounds on the nu(mu) --> nu(e) oscillation parameters. At Deltam(2)=2.8 x 10(-3) eV(2), the best-fit value of the K2Knu(mu) disappearance analysis, we set an upper limit of sin(2)2theta(mue) < 0.13 at a 90% confidence level.

Emission and absorption asymmetry in the quantum noise of a Josephson junction

We measure current fluctuations of mesoscopic devices in the quantum regime, when the frequency is of the order of or higher than the applied voltage or temperature. Detection is designed to probe separately the absorption and emission contributions of current fluctuations, i.e. the positive and negative frequencies of the Fourier transformed nonsymmetrized noise correlator. It relies on measuring the quasiparticles photon assisted tunneling current across a superconductor-insulator-superconductor junction (the detector junction) caused by the excess current fluctuations generated by quasiparticles tunneling across a Josephson junction (the source junction). We demonstrate unambiguously that the negative and positive frequency parts of the nonsymmetrized noise correlator are separately detected and that the excess current fluctuations of a voltage biased Josephson junction present a strong asymmetry between emission and absorption.

[Obstructive Sleep Apnea Syndrom during pregnancy: prevalence of main symptoms and relationship with Pregnancy Induced-Hypertension and Intra-Uterine Growth Retardation]

OBJECTIVE

To investigate the frequency of main symptoms of Obstructive Sleep Apnea Syndrom (OSAS) and their relationship with Pregnancy Induced-Hypertension (PIH) as well as Intrauterine Growth Retardation (IGR) as suggested by recent studies.

METHODOLOGY

Four hundred (and) thirty-eight enquiry forms completed during post-partum period were analysed, after exclusion of multiple pregnancies. Collected data were demographic characteristics, obstetrical events, sleep disorders during last trimester, screening of snoring and vigilance troubles with an Epworth score.

RESULTS

Forty-five percentages of the patients reported to have habitual snoring during pregnancy. Among these, 85% were non-snorers before pregnancy. Daytime somnolence concerned 84,5% of the population with an Epworth score significatively increased (P<0,0001). The prevalence of PIH was found to be 4,5%, with two apparently independent risk factors: the body mass index (OR=1,1) and an association between snoring and increased vigilance trouble (OR=2,6). No statistical difference was found concerning IGR.

CONCLUSIONS

SAS symptoms are frequent during pregnancy and snoring appears to be linked with PIH. However, polysomnographic data are not yet sufficient to explain pathophysiological mechanisms and find relevant diagnostic markers during pregnancy.

Search for coherent charged pion production in neutrino-carbon interactions

We report the result from a search for charged-current coherent pion production induced by muon neutrinos with a mean energy of 1.3 GeV. The data are collected with a fully active scintillator detector in the K2K long-baseline neutrino oscillation experiment. No evidence for coherent pion production is observed, and an upper limit of is set on the cross section ratio of coherent pion production to the total charged-current interaction at 90% confidence level. This is the first experimental limit for coherent charged pion production in the energy region of a few GeV.

Hernie diaphragmatique maternelle pendant la grossesse

We report two cases of maternal diaphragmatic hernia during pregnancy. Diaphragmatic hernia is an unusual and severe disease. Maternal and fetal prognosis are threatened. Diagnosis is uncertain when confronted to respiratory and digestive symptoms without any specificity. The chest X ray is the first exam to perform. The objective of this work is to discuss the management of such a pathology in terms of ways of delivery and surgical cure of hernia.

Evidence for muon neutrino oscillation in an accelerator-based experiment

We present results for nu(mu) oscillation in the KEK to Kamioka (K2K) long-baseline neutrino oscillation experiment. K2K uses an accelerator-produced nu(mu) beam with a mean energy of 1.3 GeV directed at the Super-Kamiokande detector. We observed the energy-dependent disappearance of nu(mu), which we presume have oscillated to nu(tau). The probability that we would observe these results if there is no neutrino oscillation is 0.0050% (4.0 sigma).

Direct observation of dynamical bifurcation between two driven oscillation states of a Josephson junction

We performed a novel phase-sensitive microwave reflection experiment which directly probes the dynamics of the Josephson plasma resonance in both the linear and the nonlinear regime. When the junction was driven below the plasma frequency into the nonlinear regime, we observed for the first time the transition between two different dynamical states predicted for nonlinear systems. In our experiment, this transition appears as an abrupt change in the reflected signal phase at a critical excitation power. This controlled dynamical switching can form the basis of a sensitive amplifier, in particular, for the readout of superconducting qubits.

[Risk factors of postpartum hemorrhage during labor and clinical and pharmacological prevention]

Prevention of postpartum hemorrhage (PPH) is a major concern in regards to its impact on maternal morbidity and mortality. While established risk factors can be identified among risk factors of PPH during labor after multivariate analysis: prolonged labor, oxytocin stimulation of labor, cesarean section, instrumental delivery, genital lacerations and episiotomy, prolonged third stage of labor, retained placenta; other risk factors are still uncertain: induction of labor, hyperthermia or chorioamniotitis, analgesia or anesthesia, macrosomia, various cesarean section techniques. Isolated identified risk factors have a moderate incidence on PPH, but their cumulation in one patient is a potential high risk. Among active management schemes of third stage of labor for PPH prevention, the most efficient technique seems to be direct injection of oxytocin when the baby's shoulders are delivered, associated with controlled cord traction. If this technique is a must for high-risk patients for PPH, and seems efficient for every patient, a correctly performed procedure requires the presence of a competent professional in addition to the midwife or obstetrician in charge of delivery, and a permanent attention so the length of third stage of labor is shortened. The alternative use of prophylactic misoprostol in the third stage of labor is less effective than injectable uterotonics in reducing PPH, and is associated with more side effects (severe shivering, pyrexia, diarrhea). None of other described prophylactic methods have proved efficiency: early suckling, umbilical blood drainage, oxytocin umbilical vein injection, among others. A decrease in PPH prevalence should be obtained by particular attention on data from the early postpartum period, active diffusion of effective prophylactic techniques, and an appropriate choice in regards to each delivery unit organization.

RF-driven Josephson bifurcation amplifier for quantum measurement

We have constructed a new type of amplifier whose primary purpose is the readout of superconducting quantum bits. It is based on the transition of a rf-driven Josephson junction between two distinct oscillation states near a dynamical bifurcation point. The main advantages of this new amplifier are speed, high sensitivity, low backaction, and the absence of on-chip dissipation. Pulsed microwave reflection measurements on nanofabricated Al junctions show that actual devices attain the performance predicted by theory.

[Respiratory disorders during sleep in the pregnant woman]

Sleep disordered breathing can occur during pregnancy due to the development of hormonal changes and respiratory function abnormalities that perturb patency of the upper airways. Habitual snoring has been described in 25 p. 100 of the women during the third trimester of pregnancy. The incidence of sleep apnea hypopnea syndrome is unknown due to the lack of longitudinal epidemiological data, and results of the main studies are in favor of upper airway resistance syndrome. However, these sleep-related breathing disorders are more frequently associated with maternal and fetal complications such as maternal hypertension, pre eclampsia and intrauterine growth restriction. This article points out the importance of such associations because of the efficacy of continuous positive airway pressure on the regression of these nocturnal respiratory and vascular complications.

Magnetic-field-dependent quasiparticle energy relaxation in mesoscopic wires

In order to find out if magnetic impurities can mediate interactions between quasiparticles in metals, we have measured the effect of a magnetic field B on the energy distribution function f(E) of quasiparticles in two silver wires driven out of equilibrium by a bias voltage U. In a sample showing sharp distributions at B=0, no magnetic field effect is found, whereas, in the other sample, rounded distributions at low magnetic field get sharper as B is increased, with a characteristic field proportional to U. Comparison is made with recent calculations of the effect of magnetic-impurities-mediated interactions taking into account Kondo physics.

[Medical-legal aspects: the obstetrician as a defendant or as an expert]

Most claims ab out term intrapartum fetal asphyxia (or cerebral palsy presumed to be in relation with it) are based on abnormal intrapartum fetal heart rate patterns, and presumed excessive delay from decision-to-delivery and/or inadequate care. For the obstetrician, whether as a defendant or a judicial expert, the difficulty lies in data interpretation which should not be reduced to an analysis of fetal monitoring, but should consider the context, the explorations used to be sure of abnormal fetal heart rate interpretation, and appropriate delay for delivery in light of the findings.

Dephasing by extremely dilute magnetic impurities revealed by Aharonov-Bohm oscillations

We have probed the magnetic field dependence of the electron phase coherence time tau(phi) by measuring the Aharonov-Bohm conductance oscillations of mesoscopic Cu rings. Whereas tau(phi) determined from the low-field magnetoresistance saturates below 1 K, the amplitude of Aharonov-Bohm h/e oscillations increases strongly on a magnetic field scale proportional to the temperature. This provides strong evidence that a likely explanation for the frequently observed saturation of tau(phi) at low temperature in weakly disordered metallic thin films is the presence of extremely dilute magnetic impurities.

[A few practical ideas concerning the application of the law on voluntary pregnancy interruption]

The law on voluntary pregnancy termination has been modified in France. Many questions are currently raised concerning its application. We provide a review discussing available elements needed to answer these questions.

[Torsion of the accessory spleen: an atypical etiology for acute abdomen]

The accessory spleen is often a incidental discovery. The accessory post-accidental spleen are unusual. The torsion of a movable spleen is possible and represent about 0.2 to 0.3% of splenectomy. But the torsion of an accessory spleen is exceptional. A case of acute torsion of an accessory spleen is reported. In a 26-year-old women was admitted with acute abdominal pain. The abdominal ultrasound and the abdominal X-Ray are no specific. In the face of the acute pain, a laparoscopy was necessary. At laparoscopy, the patient was found to have torsion and infarction of an accessory spleen in the pelvis. The treatment was a splenectomy and the evolution was favorable.

Biochemical and physiological studies of the small heat shock protein Lo18 from the lactic acid bacterium Oenococcus oeni

The small heat shock protein (smHSP) family has been extensively studied in eukaryotic cells. SmHSP assemble into large multimeric structures and possess chaperone activity that can prevent protein aggregation in vitro. Few studies on prokaryotic smHSP are actually available and no smHSP from lactic acid bacteria has been characterized at a biochemical level to date. Here we report on the Lo18 membrane-associated smHSP from the lactic acid bacterium Oenococcus oeni. Using size exclusion chromatography, nondenaturing pore-exclusion PAGE and in vitro and in vivo cross-linking experiments, the multimeric structure of Lol8 from O. oeni or expressed in Escherichia coli was investigated. In vitro, Lo18 is able to form a trimer and a higher oligomer which could be a dodecamer. Experiments strongly suggest that the same structures exist in vivo. First, Lo18 prevented thermal aggregation of citrate synthase and lactate dehydrogenase even at 60degreesC. These findings showed that the prokaryotic smHSP Lo18 can function as a molecular chaperone in vitro. Second, Lo18 did not protect lactate dehydrogenase from thermal inactivation and did not assist in enzymatic activity restoration after thermal aggregation, suggesting that other components may be needed for the refolding of the enzyme in an active conformation. Third, we showed that membrane association of Lo18 depends on the temperature upshift. Moreover, expression of this smHSP was induced by administration of a membrane fluidiser, the benzyl alcohol, suggesting that Lo18 expression could be regulated by the level of membrane fluidity.

[Neonatal bacterial infection by maternal-fetal contamination: for a change in approach? 2. Uncertainties and proposals]

Based on a critical analysis of the literature, it is clear that even though mortality has decreased to 10-15%, the prevalence of neonatal bacterial infections remains dramatically stable. Precise risk factors can be identified in most cases of neonatal infection, but remain uncertain in many others: Streptococcus agalactiae is found in only 40% of the cases of sepsis; Escherichia coli, Haemophilus influenzae, Pneumococcus, and group A Streptococcus strains should also be considered for a real prophylactic strategy; context (prematurity), lack of a consensual attitude for intrapartum strategies; management schemes for asymptomatic neonates. Based on these observations, we make proposals for a realistic attitude for everyday practice based on risk factors, maternal and neonatal bacterial sampling procedures, and modalities for neonatal antibiotic therapy.

[Neonatal bacterial infection by maternal-fetal contamination: for a change in approach? 1. Detection of Streptococcus agalactiae infection: methods and evaluation of results]

Perinatal group B streptococcal infection has been the subject of numerous studies and despite guidelines established during the last decade remains a frequent disease with high mortality. The basic aim of the guidelines is to screen for Streptococcus agalactiae during the antepartum period in order to institute antibiotic therapy during delivery. A critical review of the literature highlights the real impact and adverse effect of these guidelines: difficult application (only two-thirds of all maternity units have a protocol and compliance is only 75%), maternal risks of antibiotic therapy (especially the emergence of resistant Gram negative bacteria), fetal risks (accentuation of neonatal sepsis with resistant strains, retarded neonatal infections, frequent use of antibiotics with a broader spectrum, higher frequency of nosocomial sepsis).

[Complications of laparoscopy in gynecology]

In the field of surgery the development of operative laparoscopy has been one of the most important steps forward over the past fifteen years. This technique has become the surgical treatment of choice for a number of indications in gynaecology. The advantages of laparoscopy as compared with laparotomy are weil known, and assessment of the risk of complications is essential. A multicentric study was carried out in seven top French centres for laparoscopic gynaecological surgery. This series runs over a period of nine years and covers 29,966 diagnostic and operative laparoscopies. The risk of complications has been assessed according to the complexity of the laparoscopic procedure in question. The means of diagnosis and treatment of the complications have been analysed together with the importance of the surgeon's degree of experience. The mortality rate is 3.33 per hundred thousand laparoscopies. The overall complication rate is 4.64 per thousand laparoscopies (139 cases). The rate of complications requiring laparotomy is 3.20 per thousand (96 cases). The complication rate is significantly correlated with the complexity of the laparoscopic procedure (p = 0.0001). One out of three complications (34.1%; 43 cases) occurred while setting up for laparoscopy, and one out of four complications (28.6%) were not diagnosed during the operation. As new indications for laparoscopic surgery in gynaecology have appeared, there has been a parallel and statistically significant increase in the rate of urological complications (p = 0.001). Increased experience of the surgeons has had three consequences: a statistically significant drop in the number of bowel injuries (p = 0.0003), a drop in the rate of complications requiring laparotomy for those laparoscopic surgical procedures which are weil-defined (p = 0.01) and a change in the way complications are treated, with a significant increase in the proportion of incidents treated by laparoscopy (p = 0.0001). Laparoscopic surgery is a reliable technique. The risk of complications exists whatever the indication for laparoscopy. None of the phases in the operation must be neglected. The risk of accidents being overlooked means that the methods for postoperative follow-up must be adapted, bearing in mind the shorter hospital stay. The part played by the surgeon's experience raises the major problem of practitioner training.

Cytokine mRNA expression in mouse colon: IL-15 mRNA is overexpressed and is highly sensitive to a fibre-like dietary component (short-chain fructo-oligosaccharides) in an Apc gene manner

On the basis of studies using the Min mouse model of colon carcinogenesis, we have recently proposed that a fibre-like food (short-chain fructo-oligosaccharides, sc-FOS) fermented in the colon may stimulate a mechanism of cancer immunosurveillance. In the present paper, we have investigated the expression of cytokines as potential effector molecules. Interleukin (IL-)4, IL-5, IL-13, IL-15 and interferon (INF)-gamma mRNAs were detected by a multi-probe ribonuclease protection assay in C57BL/6J and Min mouse colons. IL-15 mRNA expression was significantly amplified (P=0.01) by the sc-FOS-enriched diet in the colon of Min mice.

Electrodynamic dip in the local density of states of a metallic wire

We have measured the differential conductance of a tunnel junction between a thin metallic wire and a thick ground plane, as a function of the applied voltage. We find that near zero voltage, the differential conductance exhibits a dip, which scales as 1/square root of [V] down to voltages V approximately 10k(B)T/e. The precise voltage and temperature dependence of the differential conductance is accounted for by the effect on the tunneling density of states of the macroscopic electrodynamics contribution to electron-electron interaction, and not by the short-ranged screened-Coulomb repulsion at microscopic scales.

Multiple Andreev reflections revealed by the energy distribution of quasiparticles

We have performed the tunnel spectroscopy of the energy distribution function of quasiparticles in 5-microm-long silver wires connected to superconducting reservoirs biased at different potentials. The distribution function f(E) presents several steps, which are manifestations of multiple Andreev reflections at the NS interfaces. The rounding of the steps is well explained by electron-electron interactions.

[Management of premature rupture of the membranes at term: how long to delay? Results of a prospective multicentric study in 713 cases]

OBJECTIVE

The aim of our study was to define he best delay for management of spontaneous rupture of the membranes at term.

MATERIALS AND METHODS

We conducted a prospective multicentric study in western France defining 3 groups of expectancy (6, 12 and 24 hours) to assess obstetrical, neonatal and maternal outcomes.

RESULTS

We included 713 patients. There was no significant difference in neonatal and maternal morbidity between the 3 groups. The rate of cesarean section was statistically higher in the 6-hour group (12%). There was no statistical difference between 12 and 24 hours but the rate was lower in the 12-hour group (5.5 versus 7.9%).

CONCLUSION

Based on our findings and a review of the literature, we have decided that in cased of premature rupture of the membranes at term, a 12 hour delay is best. At most two prostaglandin maturations can be performed in unfavorable cervixes.

Only fibres promoting a stable butyrate producing colonic ecosystem decrease the rate of aberrant crypt foci in rats

BACKGROUND

Dietary fibres have been proposed as protective agents against colon cancer but results of both epidemiological and experimental studies are inconclusive.

AIMS

Hypothesising that protection against colon cancer may be restricted to butyrate producing fibres, we investigated the factors needed for long term stable butyrate production and its relation to susceptibility to colon cancer.

METHODS

A two part randomised blinded study in rats, mimicking a prospective study in humans, was performed using a low fibre control diet (CD) and three high fibre diets: starch free wheat bran (WB), type III resistant starch (RS), and short chain fructo-oligosaccharides (FOS). Using a randomised block design, 96 inbred rats were fed for two, 16, 30, or 44 days to determine the period of adaptation to the diets, fermentation profiles, and effects on the colon, including mucosal proliferation on day 44. Subsequently, 36 rats fed the same diets for 44 days were injected with azoxymethane and checked for aberrant crypt foci 30 days later.

RESULTS

After fermentation had stabilised (44 days), only RS and FOS produced large amounts of butyrate, with a trophic effect in the large intestine. No difference in mucosal proliferation between the diets was noted at this time. In the subsequent experiment one month later, fewer aberrant crypt foci were present in rats fed high butyrate producing diets (RS, p=0.022; FOS, p=0.043).

CONCLUSION

A stable butyrate producing colonic ecosystem related to selected fibres appears to be less conducive to colon carcinogenesis.

[Major vascular complications from gynecologic laparoscopy]

OBJECTIVE

To specify the circumstances of occurence, the means of diagnosis, the risk factors and the means of prevention for major vascular injuries (MVI) during gynecologic laparoscopic procedure.

STUDY DESIGN

Retrospective case review study of 24 patients.

RESULTS

Twenty-four patients with 31 MVI were identified. The average age of the patients was 32.8 +/- 10.6 years and the mean body index mass was 22.4 +/- 4.0 kg/m2. Three of four of the MVI occurred during the setting-up phase of laparoscopy (19 cases; 79.2%). In five cases (20.8%) MVI occurred during the laparoscopic surgical procedure. Fifteen of the MVI occurring during the set up phase were secondary to insertion of the umbilical trocar and four to insertion of the needle used to create the pneumoperitoneum. A minimum of six MVI secondary to insertion of the umbilical trocar were observed with disposable trocars. In every case diagnosis was performed during the laparoscopic procedure. Five patients (20.8%) died and three others (12.5%) presented serious complications (phlebitis (one case); ischemia (two cases) with a reoperation for one patient).

CONCLUSION

MVI are rare but serious complications of gynecologic laparoscopy. Prevention relies on the surgeon's experience and strict respect of the safety rules. In the vast majority of cases, it is necessary to convert to laparotomy immediately, calling in a vascular surgeon.