Obstacles and Opportunities: Funding Research at the 1890 Land Grant Institutions

Similar to other university faculties, faculty members at 1890 land grant institutions are expected to support their research programs with grants from sources outside their institutions. Although the expectation of securing grants has not received the public attention that the publish or perish dictum has, faculty at the 1890 institutions seeking promotion and tenure must increasingly demonstrate that they can procure grant funds. Numerous inhibitive factors, however, tend to attenuate the success of 1890 faculty in obtaining research grant funding and in implementing such research projects. In this study, three key factors are examined: political, research infrastructure, and faculty initiative. The perceived importance of benefits of conducting research is also examined. Descriptive statistics and analysis of covariance are used to evaluate potential barriers to research, faculty access to information about research grants programs, opportunities to compete for grants, and experience in obtaining competitive grants. Data for this analysis are taken from a probability sample of faculty members at the 1890 land grant institutions and Tuskegee University. Also, activities are proposed that need to be implemented in order to minimize the factors preventing many scientists at the 1890 institutions from obtaining more competitive grants

Sociodemographic Predictors of Rural Poverty: A Regional Analysis

The focus of the present study is to determine the extent to which the socio-demographic variables of education, occupation, number of children, race, sex, age, and willingness to travel for employment and predictors of a rural family\u27s level of poverty. Discriminant analysis is employed to assess the accuracy of these variables in - discriminating between poor and nonpoor families randomly selected from thirty low income, rural counties in ten contiguous southeastern states. The results are supportive of previous studies as these variables are found to be statistically significant discriminants between the poor and the nonpoor. The profile of a rural poor head of household is a poorly educated, semi-skilled, female, black, farm resident who tends to be old, have a large number of children, and be less willing to travel for employment outside of one\u27s immediate area

Radiation Pressure Supported Starburst Disks and AGN Fueling

We consider the structure of marginally Toomre-stable starburst disks under the assumption that radiation pressure on dust grains provides the dominant vertical support against gravity. This is particularly appropriate when the disk is optically thick to its own IR radiation, as in the central regions of ULIRGs. Because the disk radiates at its Eddington limit, the Schmidt-law for star formation changes in the optically-thick limit, with the star formation rate per unit area scaling as Sigma_g/kappa, where Sigma_g is the gas surface density and kappa is the mean opacity. We show that optically thick starburst disks have a characteristic flux and dust effective temperature of F ~ 10^{13} L_sun/kpc^2 and T_eff ~ 90K, respectively. We compare our predictions with observations and find good agreement. We extend our model from many-hundred parsec scales to sub-parsec scales and address the problem of fueling AGN. We assume that angular momentum transport proceeds via global torques rather than a local viscosity. We account for the radial depletion of gas due to star formation and find a strong bifurcation between two classes of disk models: (1) solutions with a starburst on large scales that consumes all of the gas with little fueling of a central AGN and (2) models with an outer large-scale starburst accompanied by a more compact starburst on 1-10 pc scales and a bright central AGN. The luminosity of the latter models is in many cases dominated by the AGN. We show that the vertical thickness of the starburst disk on pc scales can approach h ~ r, perhaps accounting for the nuclear obscuration in some Type 2 AGN. We also argue that the disk of young stars in the Galactic Center may be the remnant of such a compact nuclear starburst.Comment: 26 pages, 9 figures, emulateapj, accepted to ApJ, minor changes, discussion tightened, references adde

Theory, construction, and applications of the water table

This thesis document was issued under the authority of another institution, not NPS. At the time it was written, a copy was added to the NPS Library collection for reasons not now known.  It has been included in the digital archive for its historical value to NPS.  Not believed to be a CIVINS (Civilian Institutions) title.The object of this thesis is threefold, to present the theoretical analogy between the flow of a compressible gas, such as air, and the flow of water with a free surface, to describe the details of construction of the water table which utilizes the above analogy, and to outline the demonstrate the applications of the water table in the investigation of air flow.http://www.archive.org/details/theoryconstructi00smolLieutenant Commander, United States Nav

Dust emissivity in the Submm/Mm: SCUBA and SIMBA observations of Barnard 68

We have observed the dark cloud Barnard 68 with SCUBA at 850 um and with SIMBA at 1.2 mm. The submillimetre and millimetre dust emission correlate well with the extinction map of Alves, Lada and Lada (2001).The A_V/850um correlation is clearly not linear and suggests lower temperatures for the dust in the inner core of the cloud. Assuming a model for the temperature gradient, we derive the cloud-averaged dust emissivities (normalised to the V-Band extinction efficiency) at 850 um and 1.2 mm. We find k_850um/k_V = 4.0 +/- 1.0 x 10^-5 and k_1.2mm/k_V = 9.0 +/- 3.0 x 10^-6. These values are compared with other determinations in this wavelength regime and with expectations for models of diffuse dust and grain growth in dense clouds.Comment: 8 pages, 4 figures, A&A accepted (Letter), referee forma

The Role of Galactic Winds on Molecular Gas Emission from Galaxy Mergers

We assess the impact of starburst and AGN feedback-driven winds on the CO emission from galaxy mergers, and, in particular, search for signatures of these winds in the simulated CO morphologies and emission line profiles. We do so by combining a 3D non-LTE molecular line radiative transfer code with smoothed particle hydrodynamics (SPH) simulations of galaxy mergers that include prescriptions for star formation, black hole growth, a multiphase interstellar medium (ISM), and the winds associated with star formation and black hole growth. Our main results are: (1) Galactic winds can drive outflows of masses ~10^8-10^9 Msun which may be imaged via CO emission line mapping. (2) AGN feedback-driven winds are able to drive imageable CO outflows for longer periods of time than starburst-driven winds owing to the greater amount of energy imparted to the ISM by AGN feedback compared to star formation. (3) Galactic winds can control the spatial extent of the CO emission in post-merger galaxies, and may serve as a physical motivation for the sub-kiloparsec scale CO emission radii observed in local advanced mergers. (4) Secondary emission peaks at velocities greater than the circular velocity are seen in the CO emission lines in all models. In models with winds, these high velocity peaks are seen to preferentially correspond to outflowing gas entrained in winds, which is not the case in the model without winds. The high velocity peaks seen in models without winds are typically confined to velocity offsets (from the systemic) < 1.7 times the circular velocity, whereas the models with AGN feedback-driven winds can drive high velocity peaks to ~2.5 times the circular velocity.Comment: Accepted by ApJ; Minor revisions; Resolution tests include

Properties of Nearby Starburst Galaxies Based on their Diffuse Gamma-ray Emission

The physical relationship between the far-infrared and radio fluxes of star forming galaxies has yet to be definitively determined. The favored interpretation, the "calorimeter model," requires that supernova generated cosmic ray (CR) electrons cool rapidly via synchrotron radiation. However, this cooling should steepen their radio spectra beyond what is observed, and so enhanced ionization losses at low energies from high gas densities are also required. Further, evaluating the minimum energy magnetic field strength with the traditional scaling of the synchrotron flux may underestimate the true value in massive starbursts if their magnetic energy density is comparable to the hydrostatic pressure of their disks. Gamma-ray spectra of starburst galaxies, combined with radio data, provide a less ambiguous estimate of these physical properties in starburst nuclei. While the radio flux is most sensitive to the magnetic field, the GeV gamma-ray spectrum normalization depends primarily on gas density. To this end, spectra above 100 MeV were constructed for two nearby starburst galaxies, NGC 253 and M82, using Fermi data. Their nuclear radio and far-infrared spectra from the literature are compared to new models of the steady-state CR distributions expected from starburst galaxies. Models with high magnetic fields, favoring galaxy calorimetry, are overall better fits to the observations. These solutions also imply relatively high densities and CR ionization rates, consistent with molecular cloud studies.Comment: Accepted to Ap

The structure of protostellar envelopes derived from submillimeter continuum images

High dynamic range imaging of submillimeter dust emission from the envelopes of eight young protostars in the Taurus and Perseus star-forming regions has been carried out using the SCUBA submillimeter camera on the James Clerk Maxwell Telescope. Good correspondence between the spectral classifications of the protostars and the spatial distributions of their dust emission is observed, in the sense that those with cooler spectral energy distributions also have a larger fraction of the submillimeter flux originating in an extended envelope compared with a disk. This results from the cool sources having more massive envelopes rather than warm sources having larger disks. Azimuthally-averaged radial profiles of the dust emission are used to derive the power-law index of the envelope density distributions, p (defined by rho proportional to r^-p), and most of the sources are found to have values of p consistent with those predicted by models of cloud collapse. However, the youngest protostars in our sample, L1527 and HH211-mm, deviate significantly from the theoretical predictions, exhibiting values of p somewhat lower than can be accounted for by existing models. For L1527 heating of the envelope by shocks where the outflow impinges on the surrounding medium may explain our result. For HH211-mm another explanation is needed, and one possibility is that a shallow density profile is being maintained in the outer envelope by magnetic fields and/or turbulence. If this is the case star formation must be determined by the rate at which the support is lost from the cloud, rather than the hydrodynamical properties of the envelope, such as the sound speed.Comment: Accepted for publication in the Astrophysical Journa

Extraplanar Dust in Spiral Galaxies: Tracing Outflows in the Disk-Halo Interface

There is now ample evidence that the interstellar thick disks of spiral galaxies are dusty. Although the majority of extraplanar gas in the first few kiloparsecs above the plane of a spiral galaxy is matter that has been expelled from the thin disk, the feedback-driven expulsion does not destroy dust grains altogether (and there is not yet any good measure suggesting it changes the dust-to-gas mass ratio). Direct optical imaging of a majority of edge-on spiral galaxies shows large numbers of dusty clouds populating the thick disk to heights z~2 kpc. These observations are likely revealing a cold, dense phase of the thick disk interstellar medium. New observations in the mid-infrared show emission from traditional grains and polycyclic aromatic hydrocarbons (PAHs) in the thick disks of spiral galaxies. PAHs are found to have large scale heights and to arise both in the dense dusty clouds traced through direct optical imaging and in the diffuse ionized gas. In this contribution, we briefly summarize these probes of dust in the thick disks of spiral galaxies. We also argue that not only can dust can be used to trace extraplanar material that has come from within the thick disk, but that its absence can be a marker for newly accreted matter from the circumgalactic or intergalactic medium. Thus, observations of dust can perhaps provide a quantitative measure of the importance of "outflow versus infall" in spiral galaxies.Comment: 8 pages; Invited review for the proceedings of "The Role of Disk-Halo Interaction in Galaxy Evolution: Outflow vs. Infall?" (Ed. M. de Avillez), in Espinho, Portugal, 18-22 August 2008 ; high resolution version at http://www.nd.edu/~jhowk/Papers/papers.html#conferenc

Modelling the spectral energy distribution of galaxies. V. The dust and PAH emission SEDs of disk galaxies

We present a self-consistent model of the spectral energy distributions (SEDs) of spiral galaxies from the ultraviolet (UV) to the mid-infrared (MIR)/far-infrared (FIR)/submillimeter (submm) based on a full radiative transfer calculation of the propagation of starlight in galaxy disks. This model predicts not only the total integrated energy absorbed in the UV/optical and re-emitted in the infrared/submm, but also the colours of the dust emission based on an explicit calculation of the strength and colour of the UV/optical radiation fields heating the dust, and incorporating a full calculation of the stochastic heating of small dust grains and PAH molecules. The geometry of the translucent components of the model is empirically constrained using the results from the radiation transfer analysis of Xilouris et al. on spirals in the middle range of the Hubble sequence, while the geometry of the optically thick components is constrained from physical considerations with a posteriori checks of the model predictions with observational data. These geometrical constraints enable the dust emission to be predicted in terms of a minimum set of free parameters: the central face-on dust opacity in the B-band tau^f_B, a clumpiness factor F for the star-forming regions, the star-formation rate SFR, the normalised luminosity of the old stellar population old and the bulge-to-disk ratio B/D. We show that these parameters are almost orthogonal in their predicted effect on the colours of the dust/PAH emission. The results of the calculations are made available in the form of a large library of simulated dust emission SEDs spanning the whole parameter space of our model, together with the corresponding library of dust attenuation calculated using the same model. (see full abstract in the paper)Comment: 39 pages; accepted for publication in Astronomy & Astrophysics; For a higher resolution version of Fig.1 and Fig.20 see http://www.star.uclan.ac.uk/~ccp/index.shtm