Quest University

About: Quest University is a education organization based out in Vancouver, British Columbia, Canada. It is known for research contribution in the topics: Galaxy & Population. The organization has 83 authors who have published 150 publications receiving 3874 citations.

THE NUCLEAR SPECTROSCOPIC TELESCOPE ARRAY (NuSTAR) HIGH-ENERGY X-RAY MISSION

Abstract: The Nuclear Spectroscopic Telescope Array (NuSTAR) mission, launched on 2012 June 13, is the first focusing high-energy X-ray telescope in orbit. NuSTAR operates in the band from 3 to 79 keV, extending the sensitivity of focusing far beyond the ~10 keV high-energy cutoff achieved by all previous X-ray satellites. The inherently low background associated with concentrating the X-ray light enables NuSTAR to probe the hard X-ray sky with a more than 100-fold improvement in sensitivity over the collimated or coded mask instruments that have operated in this bandpass. Using its unprecedented combination of sensitivity and spatial and spectral resolution, NuSTAR will pursue five primary scientific objectives: (1) probe obscured active galactic nucleus (AGN) activity out to the peak epoch of galaxy assembly in the universe (at z ≾ 2) by surveying selected regions of the sky; (2) study the population of hard X-ray-emitting compact objects in the Galaxy by mapping the central regions of the Milky Way; (3) study the non-thermal radiation in young supernova remnants, both the hard X-ray continuum and the emission from the radioactive element ^(44)Ti; (4) observe blazars contemporaneously with ground-based radio, optical, and TeV telescopes, as well as with Fermi and Swift, to constrain the structure of AGN jets; and (5) observe line and continuum emission from core-collapse supernovae in the Local Group, and from nearby Type Ia events, to constrain explosion models. During its baseline two-year mission, NuSTAR will also undertake a broad program of targeted observations. The observatory consists of two co-aligned grazing-incidence X-ray telescopes pointed at celestial targets by a three-axis stabilized spacecraft. Deployed into a 600 km, near-circular, 6° inclination orbit, the observatory has now completed commissioning, and is performing consistent with pre-launch expectations. NuSTAR is now executing its primary science mission, and with an expected orbit lifetime of 10 yr, we anticipate proposing a guest investigator program, to begin in late 2014.

The last of first: the final catalog and source identifications

Abstract: The FIRST survey, begun over 20 years ago, provides the definitive high-resolution map of the radio sky. This Very Large Telescope (VLA) survey reaches a detection sensitivity of 1 mJy at 20 cm over a final footprint of 10,575 deg2 that is largely coincident with the Sloan Digital Sky Survey (SDSS) area. Both the images and a catalog containing 946,432 sources are available through the FIRST Web site (http://sundog.stsci.edu). We record here the authoritative survey history, including hardware and software changes that affect the catalog's reliability and completeness. In particular, we use recent observations taken with the JVLA to test various aspects of the survey data (astrometry, CLEAN bias, and the flux density scale). We describe a new, sophisticated algorithm for flagging potential sidelobes in this snapshot survey, and show that fewer than 10% of the cataloged objects are likely sidelobes, and that these are heavily concentrated at low flux densities and in the vicinity of bright sources, as expected. We also report a comparison of the survey with the NRAO VLA Sky Survey (NVSS), as well as a match of the FIRST catalog to the SDSS and Two Micron Sky Survey (2MASS) sky surveys. The NVSS match shows very good consistency in flux density scale and astrometry between the two surveys. The matches with 2MASS and SDSS indicate a systematic ~10-20 mas astrometric error with respect to the optical reference frame in all VLA data that has disappeared with the advent of the JVLA. We demonstrate strikingly different behavior between the radio matches to stellar objects and to galaxies in the optical and IR surveys reflecting the different radio populations present over the flux density range 1-1000 mJy. As the radio flux density declines, stellar counterparts (quasars) get redder and fainter, while galaxies get brighter and have colors that initially redden but then turn bluer near the FIRST detection limit. Implications for future radio sky surveys are also briefly discussed. In particular, we show that for radio source identification at faint optical magnitudes, high angular resolution observations are essential, and cannot be sacrificed in exchange for high signal-to-noise data. The value of a JVLA survey as a complement to Square Kilometer Array precursor surveys is briefly discussed.

Shell structure and electron-electron interaction in self-assembled InAs quantum dots

Abstract: Using far-infrared spectroscopy, we investigate the excitations of self-organized InAs quantum dots as a function of the electron number per dot, 1 ≤ ne ≤ 6, which is monitored in situ by capacitance spectroscopy. Whereas the well-known two-mode spectrum is observed when the lowest (s-) states are filled, we find a rich excitation spectrum for ne ≥ 3, which reflects the importance of electron-electron interaction in the present, strongly non-parabolic confining potential. From capacitance spectroscopy we find that the electronic shell structure in our dots gives rise to a distinct pattern in the charging energies which strongly deviates from the monotonic behavior of the Coulomb blockade found in mesoscopic or metallic structures.

Prosperity without Growth: Foundations for the Economy of Tomorrow

Abstract: Tim Jackson’s revised second edition of his Prosperity without Growth continues to provide a stimulating and accessible account of the issues facing the planet, an assessment of how we’re dealing w...

A systematic review of motivational values and conservation success in and around protected areas.

Abstract: In conservation projects in and around protected areas (PAs), a suite of policy instruments are used to promote conservation behavior in local people. Few studies have related psychological research on motivational values to conservation in PAs. We conducted a systematic review of 120 peer-reviewed articles to assess the relative frequencies of policy instruments that aimed to foster intrinsic versus extrinsic motivations to conserve. We examined how the type of motivation engendered by the instrument (i.e., intrinsic or extrinsic motivation and based on the description of how the project was designed and implemented) influenced the ecological, economic, and social success of the project. We assessed the success of the project in only the case studies that included a quantitative or qualitative analysis of success. Projects designed to foster at least one intrinsically motivating instrument were 3 times more likely to meet socioeconomic or ecological goals. Although certain types of instruments such as payments or fines tended to be based on extrinsic motivators more often than education or monitoring programs, several successful projects involving payments or fines were linked to intrinsic motivation in the local community. Thus, our results suggest that rather than debating the relative merits of specific types of policy instruments, conservationists may have more success by focusing on how different motivators, suited to specific contexts, can better empower local communities to conserve. Broadly, our results suggest the current emphasis on social justice and well-being of local communities is a positive step toward protecting the world's remaining biodiversity.