1,394 research outputs found
Anatomy of a Community-Level Fiscal Impact Model: FIT-4-NH.
Abstract: This paper describes the development of a fiscal impact tool for New Hampshire communities (HT -4-NH). FIT -4-NH belongs to a family of computergenerated fiscal impact assessment models designed to estimate the impacts to local government revenues and expenditures that result from economic changes. In the past, work in this area has centered on the completion of countylevel models for the midwestern states. FIT-4-NH is unique in that it was designed for rural community-level use in the northern New England region of the country
Impact of Commercial Search Engines and International Databases on Engineering Teaching and Research
For the last three decades, the engineering higher education and professional environments have been completely transformed by the "electronic/digital information revolution" that has included the introduction of personal computer, the development of email and world wide web, and broadband Internet connections at home. Herein the writer compares the performances of several digital tools with traditional library resources. While new specialised search engines and open access digital repositories may fill a gap between conventional search engines and traditional references, these should be not be confused with real libraries and international scientific databases that encompass textbooks and peer-reviewed scholarly works. An absence of listing in some Internet search listings, databases and repositories is not an indication of standing. Researchers, engineers and academics should remember these key differences in assessing the quality of bibliographic "research" based solely upon Internet searches
LINER/H II "Transition" Nuclei and the Nature of NGC 4569
Motivated by the discovery of young, massive stars in the nuclei of some
LINER/H II ``transition'' nuclei such as NGC 4569, we have computed
photoionization models to determine whether some of these objects may be
powered solely by young star clusters rather than by accretion-powered active
nuclei. The models were calculated with the photoionization code CLOUDY, using
evolving starburst continua generated by the the STARBURST99 code of Leitherer
et al. (1999). We find that the models are able to reproduce the emission-line
spectra of transition nuclei, but only for instantaneous bursts of solar or
higher metallicity, and only for ages of ~3-5 Myr, the period when the
extreme-ultraviolet continuum is dominated by emission from Wolf-Rayet stars.
For clusters younger than 3 Myr or older than 6 Myr, and for models with a
constant star-formation rate, the softer ionizing continuum results in an
emission spectrum more typical of H II regions. This model predicts that
Wolf-Rayet emission features should appear in the spectra of transition nuclei.
While such features have not generally been detected to date, they could be
revealed in observations having higher spatial resolution. Demographic
arguments suggest that this starburst model may not apply to the majority of
transition nuclei, particularly those in early-type host galaxies, but it could
account for some members of the transition class in hosts of type Sa and later.
The starburst models during the Wolf-Rayet-dominated phase can also reproduce
the narrow-line spectra of some LINERs, but only under conditions of
above-solar metallicity and only if high-density gas is present (n_e >~ 10^5
cm^{-3}). This scenario could be applicable to some ``Type 2'' LINERs which do
not show any clear signs of nonstellar activity.Comment: To appear in PASP. 22 pages, includes 9 figures, uses AASTeX v5.
The system integration and verification testing of an orbital maneuvering vehicle for an air bearing floor
The teleoperator and Robotics Evaluation Facility (TOREF) is composed of a 4,000 square foot precision air bearing floor, the Teleoperator Motion Base, the Target Motion and Support Simulator, the mock-ups of the Hubble Space Telescope, Multi-mission Modular Spacecraft, and the Orbital Maneuvering Vehicle (OMV). The TOREF and its general capabilities to support the OMV and other remote system simulations; the facility operating procedures and requirements; and the results of generic OMV investigations are summarized
Determining the Elemental and Isotopic Composition of the preSolar Nebula from Genesis Data Analysis: The Case of Oxygen
We compare element and isotopic fractionations measured in solar wind samples
collected by NASA's Genesis mission with those predicted from models
incorporating both the ponderomotive force in the chromosphere and conservation
of the first adiabatic invariant in the low corona. Generally good agreement is
found, suggesting that these factors are consistent with the process of solar
wind fractionation. Based on bulk wind measurements, we also consider in more
detail the isotopic and elemental abundances of O. We find mild support for an
O abundance in the range 8.75 - 8.83, with a value as low as 8.69 disfavored. A
stronger conclusion must await solar wind regime specific measurements from the
Genesis samples.Comment: 6 pages, accepted by Astrophysical Journal Letter
The Growth of Black Holes and Their Host Spheroids in (Sub)mm-loud QSOs at High Redshift
We study the growth of black holes and stellar population in spheroids at
high redshift using several (sub)mm-loud QSO samples. Applying the same
criteria established in an earlier work, we find that, similar to IR QSOs at
low redshift, the far-infrared emission of these (sub)mm-loud QSOs mainly
originates from dust heated by starbursts. By combining low-z IR QSOs and
high-z (sub)mm-loud QSOs, we find a trend that the star formation rate
(\Mstardot) increases with the accretion rate (\Mdot). We compare the
values of \Mstardot/\Mdot for submm emitting galaxies (SMGs), far-infrared
ultraluminous/hyperluminous QSOs and typical QSOs, and construct a likely
evolution scenario for these objects. The (sub)mm-loud QSO transition phase has
both high \Mdot and \Mstardot and hence is important for establishing the
correlation between the masses of black holes and spheroids.Comment: 19 pages,3 figures,submitted to Chin. J. Astron. Astrophys. This
paper was first prepared for publication on August 10th, 200
Effects of different chicken protein sources on palatability in dry adult dog food
As the demand for dog food production continues to rise, along with the number of dogs per household in the US, sustainable ingredients must be considered for the pet food industry. Consumers have a negative perspective when it comes to animal by-products in their pet’s food. However, animal by-products contribute a quality source of dietary protein, vitamins, and minerals which contribute to nutritionally complete pet foods. Along with being nutritionally complete, foods must also appeal to the dog while eating. The objective of this study was to produce formulas utilizing four different chicken protein sources, and to evaluate the effects of those protein sources on palatability in dogs. Five treatments were produced, through extrusion, using fresh mechanically deboned chicken at two different inclusion levels: (FMDC14 and FMDC25), dried chicken (DC), chicken meal (CM), and chicken by-product meal (CBPM). Four trained panels of twenty-five adult dogs, made up of majority Beagles, randomly divided by sex, were used for palatability testing using the two-bowl test. Based on the palatability results from this study, the CBPM treatment was preferred (p<0.05) over the FMDC14, FMDC25, and DC treatments. The CBPM treatment was at parity to the CM treatment (p>0.05). It can be concluded that the CBPM treatment was considered palatable to the dogs
Morphology and kinematics of the ionised gas in early-type galaxies
We present results of our ongoing study of the morphology and kinematics of
the ionised gas in 48 representative nearby elliptical and lenticular galaxies
using the SAURON integral-field spectrograph on the 4.2m William Herschel
Telescope. Making use of a recently developed technique, emission is detected
in 75% of the galaxies. The ionised-gas distributions display varied
morphologies, ranging from regular gas disks to filamentary structures.
Additionally, the emission-line kinematic maps show, in general, regular
motions with smooth variations in kinematic position angle. In most of the
galaxies, the ionised-gas kinematics is decoupled from the stellar counterpart,
but only some of them present signatures of recent accretion of gaseous
material. The presence of dust is very common in our sample and is usually
accompanied by gas emission. Our analysis of the [OIII]/Hbeta emission-line
ratios, both across the whole sample as well as within the individual galaxies,
suggests that there is no unique mechanism triggering the ionisation of the
gas.Comment: 8 pages, 2 figures, submitted to "Adaptive Optics-Assisted
Integral-Field Spectroscopy", Rutten R.G.M., Benn C.R., Mendez J., eds., May
2005, La Palma (Spain), New Astr. Rev. For full resolution PS, see
http://www.strw.leidenuniv.nl/~jfalcon/JFB_AOmeeting_color_hires.ps.g
SDSS 0956+5128: A Broad-line Quasar with Extreme Velocity Offsets
We report on the discovery of a Type 1 quasar, SDSS 0956+5128, with a
surprising combination of extreme velocity offsets. SDSS 0956+5128 is a
broad-lined quasar exhibiting emission lines at three substantially different
redshifts: a systemic redshift of z ~ 0.714 based on narrow emission lines, a
broad MgII emission line centered 1200 km/s bluer than the systemic velocity,
at z ~ 0.707, and broad H\alpha and H\beta emission lines centered at z ~
0.690. The Balmer line peaks are 4100 km/s bluer than the systemic redshift.
There are no previously known objects with such an extreme difference between
broad MgII and broad Balmer emission. The two most promising explanations are
either an extreme disk emitter or a high-velocity black hole recoil. However,
neither explanation appears able to explain all of the observed features of
SDSS 0956+5128, so the object may provide a challenge to our general
understanding of quasar physics.Comment: ApJ, accepte
Deep UV Emission from Highly Ordered AlGaN/AlN Core–Shell Nanorods
Three-dimensional core-shell nanostructures could resolve key problems existing in conventional planar deep UV light-emitting diode (LED) technology due to their high structural quality, high-quality nonpolar growth leading to a reduced quantum-confined Stark effect and their ability to improve light extraction. Currently, a major hurdle to their implementation in UV LEDs is the difficulty of growing such nanostructures from AlxGa1-xN materials with a bottom-up approach. In this paper, we report the successful fabrication of an AlN/AlxGa1-xN/AlN core-shell structure using an original hybrid top-down/bottom-up approach, thus representing a breakthrough in applying core-shell architecture to deep UV emission. Various AlN/AlxGa1-xN/AlN core-shell structures were grown on optimized AlN nanorod arrays. These were created using displacement Talbot lithography (DTL), a two-step dry-wet etching process, and optimized AlN metal organic vapor phase epitaxy regrowth conditions to achieve the facet recovery of straight and smooth AlN nonpolar facets, a necessary requirement for subsequent growth. Cathodoluminescence hyperspectral imaging of the emission characteristics revealed that 229 nm deep UV emission was achieved from the highly uniform array of core-shell AlN/AlxGa1-xN/AlN structures, which represents the shortest wavelength achieved so far with a core-shell architecture. This hybrid top-down/bottom-up approach represents a major advance for the fabrication of deep UV LEDs based on core-shell nanostructures
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