Enstatite-rich Warm Debris Dust around HD165014

We present the Spitzer/Infrared Spectrograph spectrum of the main-sequence star HD165014, which is a warm (>~ 200 K) debris disk candidate discovered by the AKARI All-Sky Survey. The star possesses extremely large excess emission at wavelengths longer than 5 \mum. The detected flux densities at 10 and 20 \mum are ~ 10 and ~ 30 times larger than the predicted photospheric emission, respectively. The excess emission is attributable to the presence of circumstellar warm dust. The dust temperature is estimated as 300-750 K, corresponding to the distance of 0.7-4.4 AU from the central star. Significant fine-structured features are seen in the spectrum and the peak positions are in good agreement with those of crystalline enstatite. Features of crystalline forsterite are not significantly seen. HD165014 is the first debris disk sample that has enstatite as a dominant form of crystalline silicate rather than forsterite. Possible formation of enstatite dust from differentiated parent bodies is suggested according to the solar system analog. The detection of an enstatite-rich debris disk in the current study suggests the presence of large bodies and a variety of silicate dust processing in warm debris disks.Comment: 10 pages, 2 tables, 3 figures, accepted for publication in The Astrophysical Journal Letter

Metal-free α-amination of secondary amines: Computational and experimental evidence for azaquinone methide and azomethine ylide intermediates

We have performed a combined computational and experimental study to elucidate the mechanism of a metal-free α-amination of secondary amines. Calculations predicted azaquinone methides and azomethine ylides as the reactive intermediates and showed that iminium ions are unlikely to participate in these transformations. These results were confirmed by experimental deuterium-labeling studies and the successful trapping of the postulated azomethine ylide and azaquinone methide intermediates. In addition, computed barrier heights for the rate-limiting step correlate qualitatively with experimental findings. © 2013 American Chemical Society

Neurology

Contains research objectives and reports on three research projects.Office of Naval Research (Nonr-609(39))U. S. Air Force (AF33(616)-7282)Army Chemical Corps (DA-18-108-405-Cml-942)U.S. Public Health Service (B-3055)U. S. Air Force (AF49(638)-1130)U.S. Public Health Service (B-3090

Characterization of charge trapping processes in fully-depleted UNIBOND SOI MOSFET subjected to γ-irradiation

An investigation of radiation effect on edgeless accumulation mode (AM) p-channel and fully-depleted enhancement mode (EM) n-channel MOSFETs, fabricated on UNIBOND silicon on insulatior wafers (SOI), is presented in the paper. Characterization of trapped charge in the gate and buried oxides of the devices was performed by measuring only the front-gate transistors. It was revealed that the irradiation effect on EM n-MOSFET is stronger than that on AM p-MOSFET. Radiation-induced positive charge in the buried oxide proved to invert back interface what causes back channel creation in EM n-MOSFET but no such effect in AM p-MOSFET has been not observed. The effect of improving the quality of both interfaces for small irradiation doses is demonstrated

Operation of Energy MicroGrids

Integrated Operation is a strategy to operate the Energy MicroGrid as an integrated system. In this strategy, a CHP plant, an electric water heater, and thermal storage were operated to support both electricity and heat networks of the Energy MicroGrid. An Integrated Optimal Power Flow was formulated and was used to investigate the advantages of this Integrated Operation. Simulations indicated that Integrated Operation minimised generation curtailment and load shedding. It also reduced electricity imported from the main grid and the operating cost.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Water Quality and Herbivory Interactively Drive Coral-Reef Recovery Patterns in American Samoa

BACKGROUND: Compared with a wealth of information regarding coral-reef recovery patterns following major disturbances, less insight exists to explain the cause(s) of spatial variation in the recovery process. METHODOLOGY/PRINCIPAL FINDINGS: This study quantifies the influence of herbivory and water quality upon coral reef assemblages through space and time in Tutuila, American Samoa, a Pacific high island. Widespread declines in dominant corals (Acropora and Montipora) resulted from cyclone Heta at the end of 2003, shortly after the study began. Four sites that initially had similar coral reef assemblages but differential temporal dynamics four years following the disturbance event were classified by standardized measures of 'recovery status', defined by rates of change in ecological measures that are known to be sensitive to localized stressors. Status was best predicted, interactively, by water quality and herbivory. Expanding upon temporal trends, this study examined if similar dependencies existed through space; building multiple regression models to identify linkages between similar status measures and local stressors for 17 localities around Tutuila. The results highlighted consistent, interactive interdependencies for coral reef assemblages residing upon two unique geological reef types. Finally, the predictive regression models produced at the island scale were graphically interpreted with respect to hypothesized site-specific recovery thresholds. CONCLUSIONS/SIGNIFICANCE: Cumulatively, our study purports that moving away from describing relatively well-known patterns behind recovery, and focusing upon understanding causes, improves our foundation to predict future ecological dynamics, and thus improves coral reef management

A Revised Age for Upper Scorpius and The Star-Formation History Among the F-Type Members of the Scorpius-Centaurus OB Association

We present an analysis of the ages and star-formation history of the F-type stars in the Upper Scorpius (US), Upper Centaurus-Lupus (UCL) and Lower Centaurus-Crux (LCC) subgroups of Scorpius-Centaurus. We find that 1) our empirical isochrones are consistent with the previously published age-rank of the Sco-Cen subgroups, 2) LCC and UCL appear to reach the main sequence turn-on at spectral types ~F4 and ~F2, respectively. An analysis of the A-type stars shows US reaching the main sequence at about spectral type ~A3. 3) The median ages for the pre-main sequence members of UCL and LCC are 16 Myr and 17 Myr, respectively, in agreement with previous studies, however we find that 4) Upper Sco is much older than previously thought. The luminosities of the F-type stars in US are typically a factor of ~2.5 less luminous than predicted for a 5 Myr old population for four sets of evolutionary tracks. We reexamine the evolutionary state and isochronal ages for the B-, A-, and G-type Upper Sco members, and the evolved M supergiant Antares, and estimate a revised mean age for Upper Sco of 11+/-1+/-2 Myr (statistical, systematic). Using radial velocities and Hipparcos parallaxes we calculate a lower limit on the kinematic expansion age for Upper Sco of >10.5 Myr (99% confidence). However, the data are statistically consistent with no expansion. We reevaluate the inferred masses for the known substellar companions in Upper Sco using the revised age. Specifically, we estimate the mass of 1RXS J1609-2105b to be 14^{+2}_{-3} Mjup, suggesting that it is a brown dwarf rather than a planet. Finally, we find the fraction of F-type stars exhibiting Ha emission and/or a K-band excess consistent with accretion to be 0/17 (<19%; 95% C.L.) in US at ~11 Myr, while UCL has 1/41 (2^{+5}_{-1}%; 68% C.L.) accretors and LCC has 1/50 (2^{+4}_{-1}%; 68% C.L.) accretors at ~16 Myr and ~17 Myr, respectively. [Abridged]Comment: Accepted for publication in ApJ. Formatted with emulateapj, 28 pages, 16 figures, 14 table

An XMM-Newton view of the young open cluster NGC 6231 -- II. The OB star population

In this second paper, we pursue the analysis of the 180 ks XMM-Newton campaign towards the young open cluster NGC 6231 and we focus on its rich OB star population. We present a literature-based census of the OB stars in the field of view with more than one hundred objects, among which 30% can be associated with an X-ray source. All the O-type stars are detected in the X-ray domain as soft and reasonably strong emitters. In the 0.5-10.0 keV band, their X-ray luminosities scale with their bolometric luminosities as $\log L_\mathrm{X} - \log L_\mathrm{bol}=-6.912\pm0.153$. Such a scaling law holds in the soft (0.5-1.0 keV) and intermediate (1.0-2.5 keV) bands but breaks down in the hard band. While the two colliding wind binaries in our sample clearly deviate from this scheme, the remaining O-type objects show a very limited dispersion (40% or 20% according to whether `cool' dwarfs are included or not), much smaller than that obtained from previous studies. At our detection threshold and within our sample, the sole identified mechanism that produces significant modulations in the O star X-ray emission is related to wind interaction. The intrinsic X-ray emission of non-peculiar O-type stars seems thus constant for a given star and the level of its X-ray emission is accurately related to the its luminosity or, equivalently, to its wind properties. Among B-type stars, the detection rate is only about 25% in the sub-type range B0-B4 and remains mostly uniform throughout the different sub-populations while it drops significantly at later sub-types. The associated X-ray spectra are harder than those of O-type stars. Our analysis points towards the detected emission being associated with a physical PMS companion >... [see paper for the complete abstract]Comment: 21 pages, 14 figures, Table 2 and Figs 2 to 5 will be available through the CDS only, accepted for publication by MNRAS, Fig 1 not included in the present preprint because of size limitation

Neurology

Contains reports on eleven research projects.U.S. Air Force (AF49(638)-1130)Army Chemical Corps (DA-18-108-405-Cml-942)U.S. Public Health Service (B-3055)National Science Foundation (Grant G-16526)U.S. Public Health Service (B-3090)U.S. Air Force (AF33(616)-7588)Office of Naval Research (Nonr-1841(70)

Neurology

Contains reports on eight research projects.United States Air Force (AF33(616)-7588, AF49(638)-1130)National Science Foundation (Grant G-16526)United States Army Chemical Corps (DA-18-108-405-Cml-942)United States Public Health Service (B-3055, B-3090)United States Navy, Office of Naval Research (Contract Nonr-1841(70)