Publisher Correction: Statistics of thermomagnetic breakdown in Nb superconducting films.

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

Statistics of thermomagnetic breakdown in Nb superconducting films.

Superconductors are well known for their ability to screen out magnetic fields. In type-II superconductors, as the magnetic field pressure is progressively increased, magnetic flux accumulates at the periphery of the sample, very much like charges accumulate in a capacitor when voltage is increased. As for capacitors, exceeding certain threshold field causes the blocked magnetic flux to abruptly penetrate into the sample. This phenomenon, triggered by a thermomagnetic instability, is somewhat analogous to the dielectric breakdown of the capacitor and leaves behind a similar Lichtenberg imprinting. Even though electrical breakdown threshold has been extensively studied in dielectrics, little information is known about the statistical distribution of the thermomagnetic breakdown in superconductors. In this work, we address this problem by performing magneto-optical imaging experiments on a Nb film where nanometric heating elements are used to rapidly erase the magnetic history of the sample. We demonstrate that the size and shape distributions of avalanches permits to unambiguously identify the transition between two regimes where either thermal diffusivity or magnetic diffusivity dominates. Clear criteria for discriminating athermal dynamic avalanches from thermally driven avalanches are introduced. This allows us to provide the first precise determination of the threshold field of the thermomagnetic breakdown and unveil the details of the transition from finger-like magnetic burst to dendritic branching morphology. These findings open a new avenue in the interdisciplinary exploration of catastrophic avalanches through non destructive repeatable experiments.

Quantitative magneto-optical investigation of superconductor/ferromagnet hybrid structures.

We present a detailed quantitative magneto-optical imaging study of several superconductor/ferromagnet hybrid structures, including Nb deposited on top of thermomagnetically patterned NdFeB and permalloy/niobium with erasable and tailored magnetic landscapes imprinted in the permalloy layer. The magneto-optical imaging data are complemented with and compared to scanning Hall probe microscopy measurements. Comprehensive protocols have been developed for calibrating, testing, and converting Faraday rotation data to magnetic field maps. Applied to the acquired data, they reveal the comparatively weaker magnetic response of the superconductor from the background of larger fields and field gradients generated by the magnetic layer.

Neurotoxicological effects associated with short-term exposure of Sprague-Dawley rats to hydrogen sulfide.

Although hydrogen sulfide (H2S) is a known neurotoxic hazard, only a limited number of experimental animal studies have examined its neurochemical or behavioral effects. Our aim was to determine if short-term inhalation exposure of rats to H2S would result in altered brain catecholamnine levels or impaired learning and memory. Three groups of adult male CD rats were tested; two groups were exposed by nose-only inhalation (0, 30, 80, 200, or 400 ppm H2S) and one group was exposed by whole-body inhalation (0, 10, 30, or 80 ppm H2S) for 3 h per day forfive consecutive days. The first group (n = 10 rats per concentration) was tested immediately following each daily nose-only H2S exposure for spatial learning with a Morris water maze. Core body temperatures were also monitored in these animals during and after the last H2S exposure. The second group of rats (n = 10 rats per concentration) was tested for spontaneous motor activity immediately following the fifth exposure. These rats were then euthanized and striatal, hippocampal, and hindbrain catecholamnine levels determined. A third group of rats (n = 5-7 rats per concentration) was pretrained on a multiple fixed- interval (FI) schedule and exposed whole-body. Daily performance on the FI schedule was compared for the week pre-exposure, for the exposure week immediately following daily exposures, and for the week postexposure. We observed significant reductions in motor activity, water maze performance, and body temperature following exposure only to high concentrations (> or = 80 ppm) of H2S. Exposure to H2S did not affect regional brain catecholamine concentrations or performance on the FI schedule. Additional studies using other measures of behavior and longer-term exposure to H2S may be required to more definitively address conditions under which H2S exposure results in behavioral toxicity.

[Epidemic of hantavirus disease in Entre-Sambre-et-Meuse: year 1992-1993. Clinical and biological aspects]. / Epidémie d'hantavirose dans l'Entre-Sambre-et-Meuse: année 1992-1993 Données cliniques et biologiques.

A multihospital study allowed us to follow a total of 62 serologically proven cases of Nephropathia epidemica (NE) in the Belgian region between Sambre and Meuse during the 1992-1993 period. The clinical picture consisted of sudden high fever (100% of the cases), headache (71%), abdominal or lumbar pains (80%) and, as a less frequent but very specific sign, acute myopia (24%). Non-specific respiratory symptoms such as a non-productive cough and an abnormal lung auscultation were found in 1 case out of 4. Frequent laboratory anomalies were thrombocytopenia (69%), left-shift leucocytosis (77%), abnormal LDH (69%) and an inflammatory syndrome (86%) with levels of C-reactive protein (CRP) elevated up to a mean of 102 mg/L, often accompanied by a marked fall of total serum cholesterol and a rise of triglycerides. Impaired kidney function is the rule (84%), nevertheless serum creatinine levels remain inferior to 150 mumol/L (1.7 mg%) in 25% of the patients. As for neurological signs, 1 case of encephalitis and 1 syndrome of Guillain-Barré were observed. Relative bradycardia (< 90 bpm) was noted in 50% of the cases with fever, whereas Doppler-echocardiography detected pericarditis in 1 case, and transient impairment of the left ventricle function in 3 cases. Frequent elevation of liver enzymes (46%) confirms the observation that from now on, Hantavirus infections should be considered in the differential diagnosis of viral hepatitis. One severe case was observed with shock, diffuse intravascular coagulation and adult respiratory distress syndrome (ARDS), followed by 5 other patients presenting with marked degrees of hypoxemia and hypocapnia. We conclude that not only the causative Hantaviral serotype, but also the degree of "systemic inflammatory response syndrome" (SIRS) seems to determine the clinical picture in Hantavirus infections.