Galactic centre star formation writ large in gamma-rays

We have modelled the high-energy astrophysics of the inner 200 pc of the Galaxy with a view to explaining the diffuse, broad-band (radio continuum to TeV gamma-ray), non-thermal signal detected from this region. Our modelling pins down the ISM parameters for the environment wherein cosmic ray (CR) electrons and ions reside in the Galactic centre (GC). We find that the magnetic field in this region is 100-300 microG, the gas density < 60 cm^-3, and that a powerful (> 200 km/s) 'super'-wind acts to remove > 95% of the cosmic rays accelerated in the region before they have time to lose their energy in situ. The ~ 10^39 erg/s carried away by the GC cosmic ray protons is precisely enough to energise the ~GeV gamma-ray emission from the Fermi 'bubbles' recently found to extend north and south of the GC out to distances of ~10 kpc, provided that the bubbles constitute thick targets to the GC protons and that the situation has reached steady state. In such a situation of 'saturation' the hard, uniform spectrum of the bubbles are explained and secondary electron synchrotron explains the non-thermal microwave emission found in WMAP data mirroring the bubbles. Given the very low density of the bubble plasma ( 5 Gyr. Our scenario thus has the startling implication that a GC source of nonthermal particles of time-averaged power 10^39 erg/s has persisted since the youth of the Galaxy.Comment: 7 pages, 1 figure. Accepted to the Proceedings of the 25th Texas Symposium on Relativistic Astrophysics (Heidelberg, 2010). References updates and abstract typo corrected: "100-300 mG" -> "100-300 microG

The influence of the scene on linguistic expectations: Evidence from cross-model priming in visual worlds

- Numerous studies of utterance mediated gaze in visual scenes have demonstrated that sentence processing is not only incremental but also eager: During processing, listeners form expectations about upcoming arguments and make anticipatory eye movements to relevant displayed objects. - In particular, selectional information from verbs has been shown to guide visual attention to appropriate objects; upon hearing “the boy will eat”, listeners start looking at edible objects even before they are mentioned [1, 2]. - While these studies provide valuable insights into semantic processing, it is not clear whether anticipatory eye movements indeed reflect the purely linguistic activation of likely arguments or whether these anticipatory processes are influenced by the circumscribed visual context. - We present a German cross-modal priming experiment in which we examined listeners sensitivity to selectional restrictions between verbs and their object arguments

Measurement of damping of graphite epoxy materials

Work on a damping measurement test apparatus is discussed. The device is designed to excite tube specimens in a vacuum chamber. Also some experiments were conducted on a tube specimen to confirm previously reported results. A table of data showing the results of forced vibration tests using a half ring and a free-free boundary is given. The main purpose was to study the effect of the frequency resolution on the damping ratio measurements

Measurement of damping of graphite expoxy materials

During this period damping measurements were made on the cylindrical graphite epoxy specimen using the forced-vibration test method. The specimen was carefully mounted directly on the shaker through the supporting ring and the impedance head. This was done to simulate an idealized free-free boundary condition at the two edges. The damping ratio value and the natural frequency (first mode) obtained in this experiment were 0.13% and 508.75 Hz respectively. In order to check the damping induced by the supporting ring, measurements were made with the top half of the ring removed. The specimen then was supported only by the bottom half of the ring (half ring). It was observed that the natural frequency of the specimen (first mode) increased of a value of 552.5 Hz due to the influence of the reduced mass of the supporting ring. But the damping ratio value obtained was the same as that obtained with full supporting ring, namely 0.13%

The Galactic Centre - A Laboratory for Starburst Galaxies (?)

The Galactic centre - as the closest galactic nucleus - holds both intrinsic interest and possibly represents a useful analogue to star-burst nuclei which we can observe with orders of magnitude finer detail than these external systems. The environmental conditions in the GC - here taken to mean the inner 200 pc in diameter of the Milky Way - are extreme with respect to those typically encountered in the Galactic disk. The energy densities of the various GC ISM components are typically ~two orders of magnitude larger than those found locally and the star-formation rate density ~three orders of magnitude larger. Unusually within the Galaxy, the Galactic centre exhibits hard-spectrum, diffuse TeV (=10^12 eV) gamma-ray emission spatially coincident with the region's molecular gas. Recently the nuclei of local star-burst galaxies NGC 253 and M82 have also been detected in gamma-rays of such energies. We have embarked on an extended campaign of modelling the broadband (radio continuum to TeV gamma-ray), non- thermal signals received from the inner 200 pc of the Galaxy. On the basis of this modelling we find that star-formation and associated supernova activity is the ultimate driver of the region's non-thermal activity. This activity drives a large-scale wind of hot plasma and cosmic rays out of the GC. The wind advects the locally-accelerated cosmic rays quickly, before they can lose much energy in situ or penetrate into the densest molecular gas cores where star-formation occurs. The cosmic rays can, however, heat/ionize the lower density/warm H2 phase enveloping the cores. On very large scales (~10 kpc) the non-thermal signature of the escaping GC cosmic rays has probably been detected recently as the spectacular 'Fermi bubbles' and corresponding 'WMAP haze'.Comment: Invited talk to appear in Proceedings of IAU Symposium No. 284, 2011 (R.J. Tuffs & C.C. Popescu, eds.) `The Spectral Energy Distribution of Galaxies

Disturbances of sodium in critically ill adult neurologic patients: A clinical review

Disorders of sodium and water balance are common in critically ill adult neurologic patients. Normal aspects of sodium and water regulation are reviewed. The etiology of possible causes of sodium disturbance is discussed in both the general inpatient and the neurologic populations. Areas of importance are highlighted with regard to the differential diagnosis of sodium disturbance in neurologic patients, and management strategies are discussed. Specific discussions of the etiology, diagnosis, and management of cerebral salt wasting syndrome, the syndrome of inappropriate antidiuretic hormone secretion, and central diabetes insipidus are presented, as well as the problems of overtreatment. The importance of diagnosis at an early stage of these diseases is stressed, with a recommendation for conservative management of milder cases. Copyright © 2005 by Lippincott Williams & Wilkins

Surface acoustical intensity measurements on a diesel engine

The use of surface intensity measurements as an alternative to the conventional selective wrapping technique of noise source identification and ranking on diesel engines was investigated. A six cylinder, in line turbocharged, 350 horsepower diesel engine was used. Sound power was measured under anechoic conditions for eight separate parts of the engine at steady state operating conditions using the conventional technique. Sound power measurements were repeated on five separate parts of the engine using the surface intensity at the same steady state operating conditions. The results were compared by plotting sound power level against frequency and noise source rankings for the two methods

In-space experiment on thermoacoustic convection heat transfer phenomenon-experiment definition

The definition phase of an in-space experiment in thermoacoustic convection (TAC) heat transfer phenomenon is completed and the results are presented and discussed in some detail. Background information, application and potential importance of TAC in heat transfer processes are discussed with particular focus on application in cryogenic fluid handling and storage in microgravity space environment. Also included are the discussion on TAC space experiment objectives, results of ground support experiments, hardware information, and technical specifications and drawings. The future plans and a schedule for the development of experiment hardware (Phase 1) and flight tests and post-flight analysis (Phase 3/4) are also presented. The specific experimental objectives are rapid heating of a compressible fluid and the measurement of the fluid temperature and pressure and the recording and analysis of the experimental data for the establishment of the importance of TAC heat transfer process. The ground experiments that were completed in support of the experiment definition included fluid temperature measurement by a modified shadowgraph method, surface temperature measurements by thermocouples, and fluid pressure measurements by strain-gage pressure transducers. These experiments verified the feasibility of the TAC in-space experiment, established the relevance and accuracy of the experimental results, and specified the nature of the analysis which will be carried out in the post-flight phase of the report