Theoretical study on novel electronic properties in nanographite materials

Antiferromagnetism in stacked nanographite is investigated with using the Hubbard-type model. We find that the open shell electronic structure can be an origin of the decreasing magnetic moment with the decrease of the inter-graphene distance, as experiments on adsorption of molecules suggest. Next, possible charge-separated states are considered using the extended Hubbard model with nearest-neighbor interactions. The charge-polarized state could appear, when a static electric field is present in the graphene plane for example. Finally, superperiodic patterns with a long distance in a nanographene sheet observed by STM are discussed in terms of the interference of electronic wave functions with a static linear potential theoretically. In the analysis by the k-p model, the oscillation period decreases spatially in agreement with experiments.Comment: 8 pages; 6 figures; accepted for publication in J. Phys. Chem. Solids; related Web site: http://staff.aist.go.jp/k.harigaya/index_E.htm

Observation de la mésostructure de composites polymères/noir de carbone par microscopie en champ proche

BORDEAUX1-BU Sciences-Talence (335222101) / SudocSudocFranceF

Bearing Signal Enhancement Using Taylor-<inline-formula> <tex-math notation="LaTeX">H∞H_{\infty} </tex-math> </inline-formula> Estimator Under Variable Speed Condition

International audienc

Wireless closed-loop optogenetics across the entire dorsoventral spinal cord in mice

Optoelectronic systems can exert precise control over targeted neurons and pathways throughout the brain in untethered animals, but similar technologies for the spinal cord are not well established. In the present study, we describe a system for ultrafast, wireless, closed-loop manipulation of targeted neurons and pathways across the entire dorsoventral spinal cord in untethered mice. We developed a soft stretchable carrier, integrating microscale light-emitting diodes (micro-LEDs), that conforms to the dura mater of the spinal cord. A coating of silicone–phosphor matrix over the micro-LEDs provides mechanical protection and light conversion for compatibility with a large library of opsins. A lightweight, head-mounted, wireless platform powers the micro-LEDs and performs low-latency, on-chip processing of sensed physiological signals to control photostimulation in a closed loop. We use the device to reveal the role of various neuronal subtypes, sensory pathways and supraspinal projections in the control of locomotion in healthy and spinal-cord injured mice.ISSN:1546-1696ISSN:1087-015

Safety and feasibility of laparoscopic nephrectomy for big tumors (•10 cm): a retrospective multicentric study

International audienceObjectiveEvaluate the feasibility of laparoscopic nephrectomy (LN) for big tumors.Material & MethodsData from 116 patients were retrospectively collected from 16 tertiary centres. Clinical and operative parameters, tumor characteristics, per and post operative parameters and renal function before and after surgery were analyzed.ResultsMean age and BMI were 61 y.o and 27.8 kg/m2, respectively. Males represented 63.8% and 54.4% presented symptoms at diagnosis. Median tumor size was 11 cm and 75% of the cases were performed by expert surgeons. Median operative time and blood loss were 180 min and 200ml respectively. Conversion to open surgery was necessary in 20.7%. Intra operative complications related to massive haemorrhage occurred in 16.4%, resulting in open conversion in 62.5%. Major postoperative complications occurred in only 10 patients (8.6%). In univariate analysis, intra operative complications, age and blood loss were predictive factors of conversion to open surgery. Positive surgical margins occurred in 6 patients (5.2%). None of them presented a local recurrence. Predictive factors of recurrence or progression were lymph node invasion, metastases and Furhman grade.ConclusionLN for tumors>10 cm can be performed safely. Complication rate and positive surgical margins are similar to open surgery. In experienced hands, the benefit of a mini invasive surgery remains evident

FRIPON: a worldwide network to track incoming meteoroids

Context: Until recently, camera networks designed for monitoring fireballs worldwide were not fully automated, implying that in case of a meteorite fall, the recovery campaign was rarely immediate. This was an important limiting factor as the most fragile – hence precious – meteorites must be recovered rapidly to avoid their alteration. Aims: The Fireball Recovery and InterPlanetary Observation Network (FRIPON) scientific project was designed to overcome this limitation. This network comprises a fully automated camera and radio network deployed over a significant fraction of western Europe and a small fraction of Canada. As of today, it consists of 150 cameras and 25 European radio receivers and covers an area of about 1.5 × 106 km2. Methods: The FRIPON network, fully operational since 2018, has been monitoring meteoroid entries since 2016, thereby allowing the characterization of their dynamical and physical properties. In addition, the level of automation of the network makes it possible to trigger a meteorite recovery campaign only a few hours after it reaches the surface of the Earth. Recovery campaigns are only organized for meteorites with final masses estimated of at least 500 g, which is about one event per year in France. No recovery campaign is organized in the case of smaller final masses on the order of 50 to 100 g, which happens about three times a year; instead, the information is delivered to the local media so that it can reach the inhabitants living in the vicinity of the fall. Results: Nearly 4000 meteoroids have been detected so far and characterized by FRIPON. The distribution of their orbits appears to be bimodal, with a cometary population and a main belt population. Sporadic meteors amount to about 55% of all meteors. A first estimate of the absolute meteoroid flux (mag < –5; meteoroid size ≥~1 cm) amounts to 1250/yr/106 km2. This value is compatible with previous estimates. Finally, the first meteorite was recovered in Italy (Cavezzo, January 2020) thanks to the PRISMA network, a component of the FRIPON science project