Current-feedback-stabilized laser system for quantum simulation experiments using Yb clock transition at 578 nm

We developed a laser system for the spectroscopy of the clock transition in ytterbium (Yb) atoms at 578 nm based on an interference-filter stabilized external-cavity diode laser (IFDL) emitting at 1156 nm. Owing to the improved frequency-to-current response of the laser-diode chip and the less sensitivity of the IFDL to mechanical perturbations, we succeeded in stabilizing the frequency to a high-finesse ultra-low-expansion glass cavity with a simple current feedback system. Using this laser system, we performed high-resolution clock spectroscopy of Yb and found that the linewidth of the stabilized laser was less than 320 Hz.Comment: 5 pages, 7 figure

Activation volumes in CoPtCr-SiO2 perpendicular recording media

CoPtCr-SiO2 perpendicular recording media with varying levels of SiO2 were examined by two different methods to determine the activation volume. The first is based on the sweep-rate dependence of the remanence coercivity using Sharrock's equation. The second is based on the measurement of the fluctuation field from time-dependence data, determined using a magneto-optical Kerr effect (MOKE) magnetometer. The values of V-act measured at the coercivity for both methods are almost the same, with the fluctuation field and activation volumes increasing with the SiO2 content. The difference between V-act and the grain volume measured directly from bright-field TEM images decreases as the SiO2 content increases due to the reduction of intergranular exchange coupling. The experimental results indicate that values of V-act obtained from single- and double-layered media are consistent. It was also found that the coercivity and normalized hysteresis loop slope at coercivity varied with SiO2 content, with the coercivity peaking at 8 at % SiO2 (nearly 26 vol% SiO2)

A debris-flow monitoring devices and methods bibliography

International audienceDebris-flow monitoring has two functions, warning and modeling. The warning function includes the following parameters: occurrence prediction and detection, proximity sensing, and discharge-estimation. The parameters obtained from debris-flow measurements can deduce a numerical model for creating a hazard map and designing various types of control structures to mitigate the hazards. Many devices and methods of monitoring are tabulated here for comparative study. Some of them are in operation. Advanced comparative studies lead to an improvement in debris-flow monitoring, an integrated system that can be applied to any torrent, and a breakthrough in future developments

Microbubble disruption by ultrasound and induced cavitation phenomena

Aiming at the enhancement of in vitro sonoporation effect to cells in drug delivery, cavitation phenomena ultrasonically generated in a cylindrical vessel, which is one of a 24 wellplate, were observed with long-term photography by using a digital video camera synchronized with a repeatable flash light with the duration of 1 ?s as well as by taking a number of snapshots. A suspension consisting of distilled water and microbubbles (Sonazoid ultrasound contrast agent containing C4F10 gas) was used as a test liquid in the present experiment. It was found that microbubbles were rapidly destroyed after the ultrasound irradiation and their survival numbers were reduced by half at the exposure time of 100 ms. A maximum number of cavitation bubbles, sometimes more than sixty cavitation bubbles detected in the observation volume, were generated at a certain exposure time less than one second. Cavitation bubbles were mainly observed near the second products consisting of the fragments of the shell material and the flowing gas out of the interior of individual microbubbles. By exploring the free surface oscillation of a Sonazoid suspension, we found out that the (1,1) mode with the frequency of about 5 Hz was prominent. This seems important because the flow induced by this surface oscillation as well as by the acoustic radiation pressure can provide a higher possibility to convey the second products everywhere in the liquid. Consequently cavitation bubbles can be generated at a relatively long time after the ultrasound irradiation even though the majority of microbubbles are destroyed during an earlier period. In fact plenty of cavitation bubbles were occasionally generated even at the ultrasound exposure time of five seconds.http://deepblue.lib.umich.edu/bitstream/2027.42/84289/1/CAV2009-final109.pd

Thermogenesis in skunk cabbage (Symplocarpus renifolius): New insights from the ultrastructure and gene expression profiles

Floral thermogenesis has been found in several plant species. The spadix of one thermoregulatory plant, the Eastern Asian skunk cabbage (Symplocarpus renifolius), can maintain its temperature at approximately 22-26°C for several days, even when the ambient temperature falls below freezing. There are two major stages in skunk cabbage inflorescence development: the thermogenic female stage and the non-thermogenic male stage; in the former the spadix can produce massive amounts of heat, whereas in the latter, thermogenesis is undetectable. Based on previous studies, there is a positive correlation between heat production and the abundance of mitochondria in plant tissues and cells, and genes involved in cellular respiration and mitochondrial function are significantly enhanced at the female stage. Taken together, these findings suggest that the increased respiration or mitochondrial abundance observed in thermogenic tissues may be attributable to the high expression of specific genes. This review summarizes new insights into the changes in intracellular structures and gene expression profiles of skunk cabbage spadices during the female-male transition and proposes possible processes that are essential for each stage during floral development

Diminished presynaptic GABA(B) receptor function in the neocortex of a genetic model of absence epilepsy

Changes in GABA(B) receptor subunit expression have been recently reported in the neocortexof epileptic WAG/Rij rats that are genetically prone to experience absence seizures.These alterations may lead to hyperexcitability by downregulating the function of presynapticGABA(B) receptors in neocortical networks as suggested by a reduction in paired-pulsedepression. Here, we tested further this hypothesis by analyzing the effects induced by theGABA(B) receptor agonist baclofen (0.1-10 μM) on the inhibitory events recorded in vitro fromneocortical slices obtained from epileptic (>180 day-old) WAG/Rij and age-matched, nonepilepticcontrol (NEC) rats. We found that higher doses of baclofen were required todepress pharmacologically isolated, stimulus-induced IPSPs generated by WAG/Rij neuronsas compared to NEC. We also obtained similar evidence by comparing the effects ofbaclofen on the rate of occurrence of synchronous GABAergic events recorded by WAG/Rijand NEC neocortical slices treated with 4-aminopyridine+glutamatergic receptor antagonists.In conclusion, these data highlight a decreased function of presynaptic GABA(B) receptorsin the WAG/Rij rat neocortex. We propose that this alteration may contribute toneocortical hyperexcitability and thus to absence seizures

Role of infrainguinal bypass in Buerger's disease: An eighteen-year experience

Objectives:The role of bypass to the distal arteries for patients with Buerger's disease (thromboangiitis or TAO) remains controversial because of the high incidence of graft failure. We retrospectively reviewed the results of 71 bypasses to evaluate their efficacy.Materials and methods:We performed 71 autogenous vein bypasses in 61 patients with TAO. Of the patients, 97% were heavy smokers. The indications for surgery were claudication in 41%, and ischaemic ulcer or gangrene in 59%. Of the bypasses 85% were to the crural arteries or to the arteries below the ankle. The grafts used were 53 single saphenous veins, and 18 venovenous composite grafts.Results:There were 38 graft failures, the main causes including anastomosis to a diseased artery, disease progression (which occurred in smokers after surgery), and vein graft stenosis. Of 38, 10 were restored to patency by revision surgery. Primary and secondary patency rates were 48.8% and 62.5% at 5 years, and 43.0% and 56.3% at 10 years, respectively. The patency rates of the postoperative non-smoking group was significantly higher than that of the smoking group (66.8% vs. 34.7%, p < 0.05). Thirty-six patients (59%) had successful revascularisation and returned to full-time work. However, of 28 with secondary failure, 11 underwent amputation, while 14 had persistent disabling claudication.Conclusion:Bypass to the distal arteries is an effective treatment for TAO patients, and the long-term patency is quite satisfactory as long as patients stop smoking