Leakage of long-period oscillations from the chromosphere to the corona

Copyright © 2011 ESO / EDP SciencesLong-period oscillations in a coronal diffuse structure are detected with the Transition Region And Coronal Explorer (TRACE). The EUV images of the NOAA active region 8253 are available in 171 Å and 195 Å bandpasses from 30 June to 4 July 1998. The average intensity variation is found to be connected with the CCD temperature, which varies with the orbital motion of the spacecraft. Hence, oscillations with the orbital period and its higher harmonics appear as artifacts in the light curves. After the exclusion of the orbital effects, we identified several long-period oscillations in the diffuse fan-like structure of the active region. Similar periodicities were detected in the radio emission from the chromospheric part of that active region, observed with the ground-based Nobeyama Radioheliograph (NoRH) in the 17 GHz channel. It was found that 0.221, 0.312 and 0.573 mHz oscillations were present in both EUV emission lines in the corona and the radio signal from the sunspot in the chromosphere, just beneath the active region. From the frequency values, the 1st and 3rd detected oscillations could be associated with the l = 2, n = −3 or l = 3, n = −5 and l = 1 gravity-driven solar interior modes, respectively. The appearance of these oscillations in the coronal part of the active region can be connected with the wave leakage or the evanescence of chromospheric oscillations

A novel technique for post-pyloric feeding tube placement in critically ill patients: A pilot study

Publisher's copy made available with the permission of the publisher © Australian Society of AnaesthetistsDelivery of enteral nutrition in critically ill patients is often hampered by gastric stasis necessitating direct feeding into the small intestine. Current techniques for placement of post-pyloric feeding catheters are complex, time consuming or both, and improvements in feeding tube placement techniques are required. The Cathlocator™ is a novel device that permits real time localisation of the end of feeding tubes via detection of a magnetic field generated by a small electric current in a coil incorporated in the tip of the tube. We performed a pilot study evaluating the feasibility of the Cathlocator™ system to guide and evaluate the placement of (1) nasoduodenal feeding tubes, and (2) nasogastric drainage tubes in critically ill patients with feed intolerance due to slow gastric emptying. A prospective study of eight critically ill patients was undertaken in the intensive care unit of a tertiary hospital. The Cathlocator™ was used to (1) guide the positioning of the tubes post-pylorically and (2) determine whether nasogastric and nasoduodenal tubes were placed correctly. Tube tip position was compared with data obtained by radiology. Data are expressed as median (range). Duodenal tube placement was successful in 7 of 8 patients (insertion time 12.6 min (5.3-34.4)). All nasogastric tube placements were successful (insertion time 3.4 min (0.6-10.0)). The Cathlocator™ accurately determined the position of both tubes without complication in all cases. The Cathlocator™ allows placement and location of an enteral feeding tube in real time in critically ill patients with slow gastric emptying. These findings warrant further studies into the application of this technique for placement of post-pyloric feeding tubes.R. J. Young, M. J. Chapman, R. Fraser, R. Vozzo, D. P. Chorley, S. Creedhttp://www.aaic.net.au/Article.asp?D=200430

e-Social Science and Evidence-Based Policy Assessment : Challenges and Solutions

Peer reviewedPreprin

Desynchronization and Wave Pattern Formation in MPI-Parallel and Hybrid Memory-Bound Programs

Analytic, first-principles performance modeling of distributed-memory parallel codes is notoriously imprecise. Even for applications with extremely regular and homogeneous compute-communicate phases, simply adding communication time to computation time does often not yield a satisfactory prediction of parallel runtime due to deviations from the expected simple lockstep pattern caused by system noise, variations in communication time, and inherent load imbalance. In this paper, we highlight the specific cases of provoked and spontaneous desynchronization of memory-bound, bulk-synchronous pure MPI and hybrid MPI+OpenMP programs. Using simple microbenchmarks we observe that although desynchronization can introduce increased waiting time per process, it does not necessarily cause lower resource utilization but can lead to an increase in available bandwidth per core. In case of significant communication overhead, even natural noise can shove the system into a state of automatic overlap of communication and computation, improving the overall time to solution. The saturation point, i.e., the number of processes per memory domain required to achieve full memory bandwidth, is pivotal in the dynamics of this process and the emerging stable wave pattern. We also demonstrate how hybrid MPI-OpenMP programming can prevent desirable desynchronization by eliminating the bandwidth bottleneck among processes. A Chebyshev filter diagonalization application is used to demonstrate some of the observed effects in a realistic setting.Comment: 18 pages, 8 figure

Military elites and the study of war

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67081/2/10.1177_002200275700100103.pd

Giga-Hertz quantized charge pumping in bottom gate defined InAs nanowire quantum dots

Semiconducting nanowires (NWs) are a versatile, highly tunable material platform at the heart of many new developments in nanoscale and quantum physics. Here, we demonstrate charge pumping, i.e., the controlled transport of individual electrons through an InAs NW quantum dot (QD) device at frequencies up to $1.3\,$GHz. The QD is induced electrostatically in the NW by a series of local bottom gates in a state of the art device geometry. A periodic modulation of a single gate is enough to obtain a dc current proportional to the frequency of the modulation. The dc bias, the modulation amplitude and the gate voltages on the local gates can be used to control the number of charges conveyed per cycle. Charge pumping in InAs NWs is relevant not only in metrology as a current standard, but also opens up the opportunity to investigate a variety of exotic states of matter, e.g. Majorana modes, by single electron spectroscopy and correlation experiments.Comment: 21 page

The normalisation of Food Aid: What happened to feeding people well?

In the UK, food poverty has increased in the last 15 years and the food aid supply chain that has emerged to tackle it is now roughly 10 years old. In this time, we have seen the food aid supply chain grow at a rate that has astounded many.  Recently that growth has been aided by a grant of £20m from a large supermarket chain. It appears institutionalisation is just around the corner, if not already here. It also appears that there is far greater emphasis on dealing with  the symptoms as opposed to solving the root causes of the problem. As an opinion piece, this paper reflects on some of the prevalent issues, and suggests some ways forward