Buoyancy-driven inflow to a relic cold core: the gas belt in radio galaxy 3C 386

We report measurements from an XMM-Newton observation of the low-excitation radio galaxy 3C 386. The study focusses on an X-ray-emitting gas belt, which lies between and orthogonal to the radio lobes of 3C 386 and has a mean temperature of $0.94\pm0.05$ keV, cooler than the extended group atmosphere. The gas in the belt shows temperature structure with material closer to the surrounding medium being hotter than gas closer to the host galaxy. We suggest that this gas belt involves a `buoyancy-driven inflow' of part of the group-gas atmosphere where the buoyant rise of the radio lobes through the ambient medium has directed an inflow towards the relic cold core of the group. Inverse-Compton emission from the radio lobes is detected at a level consistent with a slight suppression of the magnetic field below the equipartition value.Comment: 11 pages, 10 figures, accepted for publication in MNRA

Murine Genetic Variance in Sugar and Fat-Conditioned Flavor Preferences: Roles of Dopamine, Opioid and NMDA Receptors and Nutritive Sensing

As obesity and diabetes have emerged as a severe public health crisis, understanding the mechanisms underlying the consumption of sugars and fats has become a topic of vigorous study. From a biological standpoint, genetic dispositions, neurochemical and hormonal influences, and predetermined orosensory and postingestive signals that modulate the hunger and satiety process may govern physiological aspects of the obesity puzzle. In addition to an innate appetite and attraction for simple carbohydrates and fats, learning plays an important role in modulating preferences for sugar- and fat-rich foods in rodents, including inbred mouse strains. Marked genetic variance has been observed among murine strains in sugar and fat appetite as well as the development and persistence of sugar preferences. In particular, SWR and BALB/c inbred mouse strains differ in their sweet taste sensitivity, exhibit robust intakes of sugars and fats, and develop strong and persistent sucrose-conditioned flavor preferences (CFP). These two strains also display strong and divergent sensitivity to dopamine (DA) D1 and opioid receptor antagonists in reducing spontaneous intake of sucrose and fat as well as in the acquisition (learning) and expression (maintenance) of sucrose-CFP. Murine strain differences have also been observed in the ability of sucrose and glucose, but not fructose, to elicit CFP following intra-gastric sugar infusions, and in the differential responsiveness of strains to post-oral actions of fructose. Six approaches were employed to further examine the role of genetic variance in responsiveness of and preferences for sugars and fats in inbred SWR and BALB/c mice. A first study examined the relative preference for fructose and sucralose and sucralose + saccharin (S+S) solutions in SWR and BALB/c mice and found that ad-libitum-fed SWR, but not BALB/c mice reversed their initial preference for S+S over fructose after experience. This study also compared initial and subsequent preferences following experience for 8% fructose and 8% glucose solutions in the two strains as an index of the post-oral reinforcing actions of the two sugars. Both ad-libitum-fed and food-restricted SWR mice strongly preferred glucose to fructose in direct choice tests, whereas food-restricted, but not ad-libitum-fed BALB/c mice displayed this preference. A second study examined whether systemic administration of opioid (naltrexone: NTX) and dopamine D1 (SCH23390: SCH) receptor antagonists reduced intakes of non-nutritive 0.2% saccharin and nutritive 8% fructose solutions in BALB/c and SWR mice. Although saccharin intake was reduced similarly by SCH and NTX in BALB/c and SWR mice, SWR mice exhibited greater potencies of opioid (1.9-fold) and DA D1 (4-fold) receptor antagonism of fructose intake relative BALB/c mice. A third study examined whether BALB/c and SWR mice exhibited differential sensitivity to NTX and SCH in altering the expression (maintenance) and acquisition (learning) of fructose-CFP. SCH was more effective than NTX in reducing the expression of fructose-CFP in both strains. Whereas BALB/c mice displayed hastened extinction of acquisition of fructose-CFP following SCH, but not NTX, SCH eliminated fructose-CFP acquisition and NTX hastened extinction of fructose-CFP in SWR mice. A fourth study examined whether BALB/c and SWR mice exhibited differential sensitivity to the NMDA receptor antagonist, MK-801 in altering acquisition and expression of both sucrose- and fructose-CFP. Although acquisition of fructose- and sucrose-CFP was eliminated by MK-801, NMDA antagonism was more potent in BALB/c relative to SWR mice. MK-801 mildly reduced the magnitude of the expression of sucrose- and fructose-CFP in BALB/c mice, but blocked the expression of fructose-, but not sucrose-CFP in SWR mice. A fifth study examined whether BALB/c and SWR mice exhibit differential sensitivity to NTX and SCH in altering the acquisition and expression of fat-CFP. BALB/c and SWR mice exhibited similar fat-CFP in preferring the CS+ flavor paired with a 5% Intralipid solution over a CS- flavor paired with a 0.5% Intralipid solution. Whereas SCH blocked the expression of fat-CFP in both BALB and SWR mice, NTX reduced this response in BALB/c, but not SWR mice. In contrast, acquisition of fat-CFP was eliminated by SCH in SWR, but not BALB/c mice. Acquisition of fat-CFP was marginally impaired by NTX in BALB/c, but not SWR mice. A sixth study examined whether BALB/c and SWR mice exhibit differential sensitivity to MK-801 in altering acquisition and expression of fat-CFP. MK-801 eliminated acquisition of fat-CFP in both BALB/c and SWR mice with the latter’s response appearing to turn into an avoidance response. Expression of fat-CFP was more effectively eliminated by MK-801 in BALB/c relative to SWR mice. The myriad behavioral differences observed in BALB/c and SWR strains indicate a crucial role for genetic background in mediating the neurochemical and behavioral substrates of sweet and fat intake as well as the development and persistence of sweet and fat preferences

Microembossing of ultrafine grained Al: microstructural analysis and finite element modelling

Ultra fine grained (UFG) Al-1050 processed by equal channel angular pressing (ECAP) and UFG Al-Mg-Cu-Mn processed by high pressure torsion (HPT) were embossed at both room temperature and 300 °C, with the aim of producing micro-channels. The behaviour of Al alloys during the embossing process was analysed using finite element (FE) modelling. The cold embossing of both Al alloys is characterised by a partial pattern transfer, a large embossing force, channels with oblique sidewalls and a large failure rate of the mould. The hot embossing is characterised by straight channel sidewalls, fully transferred patterns and reduced loads which decrease the failure rate of the mould. Hot embossing of UFG Al-Mg-Cu-Mn produced by HPT shows a potential of fabrication of microelectromechanical system (MEMS) components with micro channels

A compendium of NASA Aerobee sounding rocket launchings for 1966

Compendium of Aerobee sounding rocket launchings for 196

Advanced subsonic transport propulsion

A brief review of the current NASA Energy Efficient Engine (E(3)) Project is presented. Included in this review are the factors that influenced the design of these turbofan engines and the advanced technology incorporated in them to reduce fuel consumption and improve environmental characteristics. In addition, factors such as the continuing spiral in fuel cost, that could influence future aircraft propulsion systems beyond those represented by the E(3) engines, are also discussed. Advanced technologies that will address these influencing factors and provide viable future propulsion systems are described. The potential importance of other propulsion system types, such as geared fans and turboshaft engines, is presented

MHD Simulations of AGN Jets in a Dynamic Galaxy Cluster Medium

We present a pair of 3-d magnetohydrodynamical simulations of intermittent jets from a central active galactic nucleus (AGN) in a galaxy cluster extracted from a high resolution cosmological simulation. The selected cluster was chosen as an apparently relatively relaxed system, not having undergone a major merger in almost 7 Gyr. Despite this characterization and history, the intra-cluster medium (ICM) contains quite active "weather". We explore the effects of this ICM weather on the morphological evolution of the AGN jets and lobes. The orientation of the jets is different in the two simulations so that they probe different aspects of the ICM structure and dynamics. We find that even for this cluster that can be characterized as relaxed by an observational standard, the large-scale, bulk ICM motions can significantly distort the jets and lobes. Synthetic X-ray observations of the simulations show that the jets produce complex cavity systems, while synthetic radio observations reveal bending of the jets and lobes similar to wide-angle tail (WAT) radio sources. The jets are cycled on and off with a 26 Myr period using a 50% duty cycle. This leads to morphological features similar to those in "double-double" radio galaxies. While the jet and ICM magnetic fields are generally too weak in the simulations to play a major role in the dynamics, Maxwell stresses can still become locally significant.Comment: 20 pages, 14 figures, accepted for publication in the Astrophysical Journa

VLT Observations of Turnoff stars in the Globular Cluster NGC 6397

VLT-UVES high resolution spectra of seven turnoff stars in the metal-poor globular cluster NGC 6397 have been obtained. Atmospheric parameters and abundances of several elements (Li, Na, Mg, Ca, Sc, Ti, Cr, Fe, Ni, Zn and Ba) were derived for program stars. The mean iron abundance is [Fe/H] = -2.02, with no star-to-star variation. The mean abundances of the alpha-elements (Ca, Ti) and of the iron-peak elements (Sc, Cr, Ni) are consistent with abundances derived for field stars of similar metallicity. Magnesium is also almost solar, consistent with the values found by Idiart & Th\'evenin (2000) when non-LTE effects (NLTE hereafter) are taken into account. The sodium abundance derived for five stars is essentially solar, but one object (A447) is clearly Na deficient. These results are compatible with the expected abundance range estimated from the stochastic evolutionary halo model by Argast et al. (2000) when at the epoch of [Fe/H] $\sim$ -2 the interstellar medium is supposed to become well-mixed.Comment: to appear in A&

Optical Response of Grating-Coupler-Induced Intersubband Resonances: The Role of Wood's Anomalies

Grating-coupler-induced collective intersubband transitions in a quasi-two-dimensional electron system are investigated both experimentally and theoretically. Far-infrared transmission experiments are performed on samples containing a quasi-two-dimensional electron gas quantum-confined in a parabolic quantum well. For rectangular shaped grating couplers of different periods we observe a strong dependence of the transmission line shape and peak height on the period of the grating, i.e. on the wave vector transfer from the diffracted beams to the collective intersubband resonance. It is shown that the line shape transforms with increasing grating period from a Lorentzian into a strongly asymmetric line shape. Theoretically, we treat the problem by using the transfer-matrix method of local optics and apply the modal-expansion method to calculate the influence of the grating. The optically uniaxial quasi-two-dimensional electron gas is described in the long-wavelength limit of the random-phase approximation by a local dielectric tensor, which includes size quantization effects. Our theory reproduces excellently the experimental line shapes. The deformation of the transmission line shapes we explain by the occurrence of both types of Wood's anomalies.Comment: 28 pages, 7 figures. Physical Review B , in pres

Cohomology of the minimal nilpotent orbit

We compute the integral cohomology of the minimal non-trivial nilpotent orbit in a complex simple (or quasi-simple) Lie algebra. We find by a uniform approach that the middle cohomology group is isomorphic to the fundamental group of the sub-root system generated by the long simple roots. The modulo $\ell$ reduction of the Springer correspondent representation involves the sign representation exactly when $\ell$ divides the order of this cohomology group. The primes dividing the torsion of the rest of the cohomology are bad primes.Comment: 29 pages, v2 : Leray-Serre spectral sequence replaced by Gysin sequence only, corrected typo