Post-IPO Employment and Revenue Growth for U.S. IPOs, June 1996-2010

Analyzes employment and revenue growth, survival rate, sector, location, and venture capital involvement of U.S. companies that held initial public offerings on American markets from June 1996 through 2010, with a focus on firms younger than thirty years

The Nature of the Peculiar Virgo Cluster Galaxies NGC 4064 and NGC 4424

We present a detailed study of the peculiar HI-deficient Virgo cluster spiral galaxies NGC 4064 and NGC 4424, using $^{12}$CO 1-0 interferometry, optical imaging and integral-field spectroscopic observations, in order to learn what type of environmental interactions have afected these galaxies. Optical imaging reveals that NGC 4424 has a strongly disturbed stellar disk, with banana-shaped isophotes and shells. NGC 4064, which lies in the cluster outskirts, possesses a relatively undisturbed outer stellar disk and a central bar. In both galaxies H-alpha emission is confined to the central kiloparsec. CO observations reveal bilobal molecular gas morphologies, with H-alpha emission peaking inside the CO lobes, implying a time sequence in the star formation process.Gas kinematics reveals strong bar-like non-circular motions in the molecular gas in both galaxies, suggesting that the material is radially infalling. In NGC 4064 the stellar kinematics reveal strong bar-like non-circular motions in the central 1 kpc. On the other hand, NGC 4424 has extremely modest stellar rotation velocities (Vmax ~ 30 km s-1), and stars are supported by random motions as far out as we can measure it. The observations suggest that the peculiarities of NGC 4424 are the result of an intermediate-mass merger plus ram pressure stripping. In the case of NGC 4064, the evidence suggests an already stripped "truncated/normal" galaxy that recently suffered a minor merger or tidal interaction with another galaxy. We propose that galaxies with "truncated/compact" H-alpha morphologies such as these are the result of the independent effects of ram pressure stripping, which removes gas from the outer disk, and gravitational interactions such as mergers, which heat stellar disks, drive gas to the central kpc and increase the central mass concentrations.Comment: 42 pages, 21 figure

Virginia : March and Two Step

https://digitalcommons.library.umaine.edu/mmb-ps/2491/thumbnail.jp

Magnetic Flux Sensor for Hearing and Application

A 3-D microelectronic inductor has been fabricated and characterized for use as a magnetic flux sensor, also known as a telecoil, for a hearing aid application. This telecoil was fabricated in a 0.5pm CMOS process with three metal layers. The 3-D structure is more space efficient than conventional spiral inductors and allows for an optimal number of turns for the space available. The telecoil has an inductance of 80pH, a resistance of 34kR, and a capacitance of 275pF. The integrated telecoil acts as a magnetic flux sensor by picking up the magnetic signal fiom the phone speaker. The integrated telecoil is smaller than commercially available telecoils, which may allow telecoils to be available in all types of hearing aids. The electrical response of the telecoil to a changing magnetic field is linear with respect to the input amplitude. Neglecting the noise associated with lower frequencies, it is shown that the telecoil response is not dependent on frequency, which agrees with theory. The magnitude of the telecoil signal is of the form of A + 5 where r is the distance between the speaker and telecoil, which differs from the theory. The increase in response due to the addition of a permeable core is much lower than expected. When the telecoil is combined with a high-gain low-noise amplifier, it can easily be integrated with existing microelectronic hearing aid designs. Therefore the Cherry Hooper amplifier and a single-ended amplifier were investigated. A single stage Cherry Hooper amplifier design was simulated at a gain of 29 dB, THD of -SO&, and equivalent input noise of 2.01%. A three stage Cherry Hooper design (identical stages) with a filter has a simulated gain of 84 dB, THD of -49dB, and equivalent input noise of 2.01%. The three stage amplifier also has a bandwidth of 3kHz and a driving capacity of 30pF external load capacitance. The complete single-ended amplifier design was simulated at a gain of 67dI3, THD of -48dB, equivalent input noise of 45.3%, and driving capacity of I n . external load capacitance. More research is needed to obtain conclusive experimental parameters of the amplifiers

The Trouble with Hubble Types in the Virgo Cluster

Quantitative measures of central light concentration and star formation activity are derived from R and Halpha surface photometry of 84 bright S0-Scd Virgo Cluster and isolated spiral galaxies. For isolated spirals, there is a good correlation between these two parameters and assigned Hubble types. In the Virgo Cluster, the correlation between central light concentration and star formation activity is significantly weaker. Virgo Cluster spirals have systematically reduced global star formation with respect to isolated spirals, with severe reduction in the outer disk, but normal or enhanced activity in the inner disk. Assigned Hubble types are thus inadequate to describe the range in morphologies of bright Virgo Cluster spirals. In particular, spirals with reduced global star formation activity are often assigned misleading early-type classifications, irrespective of their central light concentrations. 45+-25% of the galaxies classified as Sa in the Virgo Cluster sample have central light concentrations more characteristic of isolated Sb-Sc galaxies. The misleading classification of low concentration galaxies with low star formation rates as early-type spirals may account for part of the excess of `early-type' spiral galaxies in clusters. Thus the morphology-density relationship is not all due to a systematic increase in the bulge-to-disk ratio with environmental density.Comment: Accepted for publication in ApJ Letters. Latex aaspp4.sty, 9 pages, 2 Postscript (embedded) figures. Also available at http://www.astro.yale.edu/koopmann/preprint.htm

A two-step method for identifying photopigment opsin and rhodopsin gene sequences underlying human color vision phenotypes.

PurposeTo present a detailed, reliable long range-PCR and sequencing (LR-PCR-Seq) procedure to identify human opsin gene sequences for variations in the long wavelength-sensitive (OPN1LW), medium wavelength-sensitive (OPN1MW), short wavelength-sensitive (OPN1SW), and rhodopsin (RHO) genes.MethodsColor vision was assessed for nine subjects using the Farnsworth-Munsell 100 hue test, Ishihara pseudoisochromatic plates, and the Rabin cone-contrast threshold procedure (ColorDX, Konan Medical). The color vision phenotypes were normal trichromacy (n = 3), potential tetrachromacy (n = 3), dichromacy (n = 2), and unexplained low color vision (n = 1). DNA was isolated from blood or saliva and LR-PCR amplified into individual products: OPN1LW (4,045 bp), OPN1MW (4,045 bp), OPN1SW (3,326 bp), and RHO (6,715 bp). Each product was sequenced using specific internal primer sets. Analysis was performed with Mutation Surveyor software.ResultsThe LR-PCR-Seq technique identified known single nucleotide polymorphisms (SNPs) in OPN1LW and OPN1MW gene codons (180, 230, 233, 277, and 285), as well as those for lesser studied codons (174, 178, 236, 274, 279, 298 and 309) in the OPN1LW and OPN1MW genes. Additionally, six SNP variants in the OPN1MW and OPN1LW genes not previously reported in the NCBI dbSNP database were identified. An unreported poly-T region within intron 5(c.36+126) of the rhodopsin gene was also found, and analysis showed it to be highly conserved in mammalian species.ConclusionsThis LR-PCR-Seq procedure (single PCR reaction per gene followed by sequencing) can identify exonic and intronic SNP variants in OPN1LW, OPN1MW, OPN1SW, and rhodopsin genes. There is no need for restriction enzyme digestion or multiple PCR steps that can introduce errors. Future studies will combine the LR-PCR-Seq with perceptual behavior measures, allowing for accurate correlations between opsin genotypes, retinal photopigment phenotypes, and color perception behaviors

Dynamics of Inner Galactic Disks: The Striking Case of M100

We investigate gas dynamics in the presence of a double inner Lindblad resonance within a barred disk galaxy. Using an example of a prominent spiral, M100, we reproduce the basic central morphology, including four dominant regions of star formation corresponding to the compression maxima in the gas. These active star forming sites delineate an inner boundary (so-called nuclear ring) of a rather broad oval detected in the near infrared. We find that inclusion of self-gravitational effects in the gas is necessary in order to understand its behavior in the vicinity of the resonances and its subsequent evolution. The self-gravity of the gas is also crucial to estimate the effect of a massive nuclear ring on periodic orbits in the stellar bar.Comment: 11 pages, postscript, compressed, uuencoded. Paper and 4 figures available at ftp://pa.uky.edu/shlosman/nobel or at http://www.pa.uky.edu/~shlosman/ . Invited talk at the Centennial Nobel Symposium on "Barred Galaxies and Circumnuclear Activity," A.Sandquist et al. (Eds.), Springer-Verlag, in pres