852 research outputs found

    High incidence of Angina pectoris in patients treated with 5-fluorouracil - A planned surveillance study with 102 patients

    Get PDF
    Objective: Angina pectoris, arrhythmic sudden death and myocardial infarction, all these cardiac events have occasionally been reported during 5-fluorouracil (5-FU) chemotherapy. Underlying mechanisms leading to these events are unknown; damage to the myocytes or vasospasms have been discussed. Methods: 102 consecutive and unselected patients were monitored with 12-lead ECG, echocardiography and radionuclide ventriculography prior to the first cycle of 5-FU chemotherapy and 3 months from baseline. Results: 19% of the patients developed reversible symptoms of angina pectoris during treatment which lasted up to 12 h after cessation of the infusion. Most of the 19 patients showed corresponding ECG changes. 6 out of the 19 patients with severe angina pectoris had subsequent coronary angiography. In none of these patients the coronary angiography showed coronary artery disease, but it showed low ventricular function (ejection fraction <50%) in 2 patients. The ejection fraction did not increase overtime. Arrhythmias were screened for with Holter monitoring during 5-FU chemotherapy. The frequency of bradycardia and ventricular extrasystoles increased significantly (p < 0.05) during treatment compared to arrhythmias in Holter monitoring 3 months later. Furthermore the Qtc time in the ECG 3 months later was significantly prolonged (p < 0.05) compared to baseline values. Conclusions:The incidence of angina pectoris in patients during 5-FU treatment seems higher than previously suspected. As myocardial ischemia can be fatal, attentiveness to these symptoms and immediate treatment are crucial. Copyright (C) 2003 S. Karger AG, Basel

    Effect of pressure cycling on Iron: Signatures of an electronic instability and unconventional superconductivity

    Get PDF
    High pressure electrical resistivity and x-ray diffraction experiments have been performed on Fe single crystals. The crystallographic investigation provides direct evidence that in the martensitic bcc→hcpbcc \rightarrow hcp transition at 14 GPa the {110}bcc\lbrace 110\rbrace_{bcc} become the {002}hcp\lbrace 002\rbrace_{hcp} directions. During a pressure cycle, resistivity shows a broad hysteresis of 6.5 GPa, whereas superconductivity, observed between 13 and 31 GPa, remains unaffected. Upon increasing pressure an electronic instability, probably a quantum critical point, is observed at around 19 GPa and, close to this pressure, the superconducting TcT_{c} and the isothermal resistivity (0<T<300 0<T<300\,K) attain maximum values. In the superconducting pressure domain, the exponent n=5/3n = 5/3 of the temperature power law of resistivity and its prefactor, which mimics TcT_{c}, indicate that ferromagnetic fluctuations may provide the glue for the Cooper pairs, yielding unconventional superconductivity

    Superconductivity without Fe or Ni in the phosphides BaIr2P2 and BaRh2P2

    Full text link
    Heat capacity, resistivity, and magnetic susceptibility measurements confirm bulk superconductivity in single crystals of BaIr2_2P2_2 (Tc_c=2.1K) and BaRh2_2P2_2 (Tc_c = 1.0 K). These compounds form in the ThCr2_2Si2_2 (122) structure so they are isostructural to both the Ni and Fe pnictides but not isoelectronic to either of them. This illustrates the importance of structure for the occurrence of superconductivity in the 122 pnictides. Additionally, a comparison between these and other ternary phosphide superconductors suggests that the lack of interlayer P−PP-P bonding favors superconductivity. These stoichiometric and ambient pressure superconductors offer an ideal playground to investigate the role of structure for the mechanism of superconductivity in the absence of magnetism.Comment: Published in Phys Rev B: Rapid Communication

    Wilson ratio in Yb-substituted CeCoIn5

    Full text link
    We have investigated the effect of Yb substitution on the Pauli limited, heavy fermion superconductor, CeCoIn5_5. Yb acts as a non-magnetic divalent substituent for Ce throughout the entire doping range, equivalent to hole doping on the rare earth site. We found that the upper critical field in (Ce,Yb)CoIn5_5 is Pauli limited, yet the reduced (H,T) phase diagram is insensitive to disorder, as expected in the purely orbitally limited case. We use the Pauli limiting field, the superconducting condensation energy and the electronic specific heat coefficient to determine the Wilson ratio (RWR_{W}), the ratio of the specific heat coefficient to the Pauli susceptibility in CeCoIn5_5. The method is applicable to any Pauli limited superconductor in the clean limit.Comment: 5 pages, 1 table, 4 figure

    Superconducting phase diagram of the filled skuterrudite PrOs4Sb12

    Get PDF
    We present new measurements of the specific heat of the heavy fermion superconductor PrOs4Sb12, on a sample which exhibits two sharp distinct anomalies at Tc1= 1.89K and Tc2= 1.72K. They are used to draw a precise magnetic field-temperature superconducting phase diagram of PrOs4Sb12 down to 350 mK. We discuss the superconducting phase diagram of PrOs4Sb12 and its possible relation with an unconventional superconducting order parameter. We give a detailed analysis of Hc2(T), which shows paramagnetic limitation (a support for even parity pairing) and multiband effects

    Exzellenz, Diversität oder Effizienz? „Implicit bias“ in Berufungsverfahren als Zielkonflikte sozialer Praktiken

    Get PDF
    Gendergerechtes Diversitätsmanagement soll den Einfluss von implicit bias auf die Entscheidungsfindung in Berufungsverfahren reduzieren. Konventionelle Schulungsformate vermitteln jedoch wenig anwendbares Praxiswissen für typische kommunikative Situationen in den Sitzungen einer Berufungskommission. Wird implicit bias als soziale Praktik konzeptualisiert, lassen sich typische Zielkonflikte zwischen Diversität, Exzellenz und Effizienz in solchen Verfahren jedoch operationalisieren und mit überprüfbaren Lernzielen versehen. Dazu wurden fachübergreifend aggregierte Daten aus Berufungsprozessen an einer Schweizer Hochschule narrativ strukturiert und in die Form idealtypischer Vignetten gebracht. Ein webbasierter Videokurs (serious game) simuliert die szenische Umsetzung der sozialen Praktiken von implicit bias sowohl für die Vermittlung von Reflexionswissen als auch das Trainieren von Handlungswissen

    Fermi-surface topology of the iron pnictide LaFe2_2P2_2

    Full text link
    We report on a comprehensive de Haas--van Alphen (dHvA) study of the iron pnictide LaFe2_2P2_2. Our extensive density-functional band-structure calculations can well explain the measured angular-dependent dHvA frequencies. As salient feature, we observe only one quasi-two-dimensional Fermi-surface sheet, i.e., a hole-like Fermi-surface cylinder around Γ\Gamma, essential for s±s_\pm pairing, is missing. In spite of considerable mass enhancements due to many-body effects, LaFe2_2P2_2 shows no superconductivity. This is likely caused by the absence of any nesting between electron and hole bands.Comment: 5 pages, 4 figure

    Variation in the Meaning of Alarm Calls in Verreaux’s and Coquerel’s Sifakas (Propithecus verreauxi, P. coquereli)

    Get PDF
    The comprehension and usage of primate alarm calls appear to be influenced by social learning. Thus, alarm calls provide flexible behavioral mechanisms that may allow animals to develop appropriate responses to locally present predators. To study this potential flexibility, we compared the usage and function of 3 alarm calls common to 2 closely related sifaka species (Propithecus verreauxi and P. coquereli), in each of 2 different populations with different sets of predators. Playback studies revealed that both species in both of their respective populations emitted roaring barks in response to raptors, and playbacks of this call elicited a specific anti-raptor response (look up and climb down). However, in Verreaux’s sifakas, tchi-faks elicited anti-terrestrial predator responses (look down, climb up) in the population with a higher potential predation threat by terrestrial predators, whereas tchi-faks in the other population were associated with nonspecific flight responses. In both populations of Coquerel’s sifakas, tchi-fak playbacks elicited anti-terrestrial predator responses. More strikingly, Verreaux’s sifakas exhibited anti-terrestrial predator responses after playbacks of growls in the population with a higher threat of predation by terrestrial predators, whereas Coquerel’s sifakas in the raptor-dominated habitat seemed to associate growls with a threat by raptors; the 2 other populations of each species associated a mild disturbance with growls. We interpret this differential comprehension and usage of alarm calls as the result of social learning processes that caused changes in signal content in response to changes in the set of predators to which these populations have been exposed since they last shared a common ancestor
    • …
    corecore