BIRP: Software for interactive search and retrieval of image engineering data

Better Image Retrieval Programs (BIRP), a set of programs to interactively sort through and to display a database, such as engineering data for images acquired by spacecraft is described. An overview of the philosophy of BIRP design, the structure of BIRP data files, and examples that illustrate the capabilities of the software are provided

Management Buyouts: Creating or Appropriating Shareholder Wealth?

The name of the game in corporate America today is leverage.Whether through leveraged buyouts\u27 or leveraged recapitalizations, many of the United States\u27 largest corporations are rapidly trading equity capital for debt.\u27 This trend began only a few years ago when a small group of financial entrepreneurs, which included Carl Icahn, T.Boone Pickens, Asher Edelman,\u27 Irwin Jacobs, and Ronald Perelman, found that they could finance large stock purchases of major corporations through the use of high-yield ( junk ) bonds\u27 leading to either an acquisition of the target or its forced restructuring. The general goal of these financiers was to force a reconciliation between what they perceived as low stock prices and corporate assets of far greater potential value. Their efforts have been tremendously profitable. The corporate targets of these hostile share acquisitions, however,did not sit idly by and wait to have their shares gobbled up. The defenses they erected are now. famous because of their frequent use and colorful names: the Pac-Man defense, the scorched earth defense, shark repellents and poison pills. \u27 While these defenses proved to be an initial deterrent to hostile acquisitions, more creative financing techniques and other offensive weapons have rendered these defenses something of a Maginot Line. Target managements, searching for away to protect their shareholders, their jobs, or both, increasingly have taken the approach of fighting fire with fire-that is, using leverage and redeployment of assets in an attempt to create for themselves the same profits sought by the hostile bidder. The present-day management buyout developed primarily as a defensive response to the attacks of the financial entrepreneurs and other acquisition hungry companies. Top executives who became the equity holders in the private companies that followed buyouts generally have found this new defense as enormously profitable as the comparable offensive purchases of the financiers who initiated the first round of lever-aged stock acquisitions. Likewise, the leveraged recapitalization can be viewed largely as management\u27s attempt to effect the same reconciliation of values between stock prices and corporate assets by which a hostile bidder seeks to profit, while keeping the company independent with ownership continuing in the hands of the public shareholders.Here too, however, management will often grab a slice of the equity pie as an incentive booster in the course of revamping the corporation\u27s capital structure. It appears that like buyouts, top executives find the leveraged recapitalization quite profitable

Synthesis of Colloidal Mn2+:ZnO Quantum Dots and High-TC Ferromagnetic Nanocrystalline Thin Films

We report the synthesis of colloidal Mn2+-doped ZnO (Mn2+:ZnO) quantum dots and the preparation of room-temperature ferromagnetic nanocrystalline thin films. Mn2+:ZnO nanocrystals were prepared by a hydrolysis and condensation reaction in DMSO under atmospheric conditions. Synthesis was monitored by electronic absorption and electron paramagnetic resonance (EPR) spectroscopies. Zn(OAc)2 was found to strongly inhibit oxidation of Mn2+ by O2, allowing the synthesis of Mn2+:ZnO to be performed aerobically. Mn2+ ions were removed from the surfaces of as-prepared nanocrystals using dodecylamine to yield high-quality internally doped Mn2+:ZnO colloids of nearly spherical shape and uniform diameter (6.1 +/- 0.7 nm). Simulations of the highly resolved X- and Q-band nanocrystal EPR spectra, combined with quantitative analysis of magnetic susceptibilities, confirmed that the manganese is substitutionally incorporated into the ZnO nanocrystals as Mn2+ with very homogeneous speciation, differing from bulk Mn2+:ZnO only in the magnitude of D-strain. Robust ferromagnetism was observed in spin-coated thin films of the nanocrystals, with 300 K saturation moments as large as 1.35 Bohr magneton/Mn2+ and TC > 350 K. A distinct ferromagnetic resonance signal was observed in the EPR spectra of the ferromagnetic films. The occurrence of ferromagnetism in Mn2+:ZnO and its dependence on synthetic variables are discussed in the context of these and previous theoretical and experimental results.Comment: To be published in the Journal of the American Chemical Society Web on July 14, 2004 (http://dx.doi.org/10.1021/ja048427j

Cation composition effects on oxide conductivity in the Zr_2Y_2O_7-Y_3NbO_7 system

Realistic, first-principles-based interatomic potentials have been used in molecular dynamics simulations to study the effect of cation composition on the ionic conductivity in the Zr2Y2O7-Y3NbO7 system and to link the dynamical properties to the degree of lattice disorder. Across the composition range, this system retains a disordered fluorite crystal structure and the vacancy concentration is constant. The observed trends of decreasing conductivity and increasing disorder with increasing Nb5+ content were reproduced in simulations with the cations randomly assigned to positions on the cation sublattice. The trends were traced to the influences of the cation charges and relative sizes and their effect on vacancy ordering by carrying out additional calculations in which, for example, the charges of the cations were equalised. The simulations did not, however, reproduce all the observed properties, particularly for Y3NbO7. Its conductivity was significantly overestimated and prominent diffuse scattering features observed in small area electron diffraction studies were not always reproduced. Consideration of these deficiencies led to a preliminary attempt to characterise the consequence of partially ordering the cations on their lattice, which significantly affects the propensity for vacancy ordering. The extent and consequences of cation ordering seem to be much less pronounced on the Zr2Y2O7 side of the composition range.Comment: 22 pages, 8 figures, submitted to Journal of Physics: Condensed Matte

A lightcone catalogue from the Millennium-XXL simulation

Future galaxy surveys require realistic mock catalogues to understand and quantify systematics in order to make precise cosmological measurements. We present a halo lightcone catalogue and halo occupation distribution (HOD) galaxy catalogue built using the Millennium-XXL simulation. The halo catalogue covers the full sky, extending to z = 2.2 with a mass resolution of ∼1011 h−1 M⊙. We use this to build a galaxy catalogue, which has an r-band magnitude limit of r < 20.0, with a median redshift of z ∼ 0.2. A Monte Carlo HOD method is used to assign galaxies to the halo lightcone catalogue, and we evolve the HODs to reproduce a target luminosity function; by construction, the luminosity function of galaxies in the mock is in agreement with the Sloan Digital Sky Survey (SDSS) at low redshifts and the Galaxy and Mass Assembly (GAMA) survey at high redshifts. A Monte Carlo method is used to assign a 0.1(g − r) colour to each galaxy, and the colour distribution of galaxies at different redshifts agrees with measurements from GAMA. The clustering of galaxies in the mock for galaxies in different magnitude and redshift bins is in good agreement with measurements from SDSS and GAMA, and the colour-dependent clustering is in reasonable agreement. We show that the baryon acoustic oscillation can be measured in the mock catalogue, and the redshift-space distortions are in agreement with measurements from SDSS illustrating that this catalogue will be useful for upcoming surveys

Two massive star-forming regions at early evolutionary stages

We report sensitive ATCA radio-continuum observations toward IRAS 15596-5301 and 16272-4837, two luminous objects (> 2x10^4 Lsun) thought to represent massive star-forming regions in early stages of evolution (due to previously undetected radio emission at the 1-sigma level of 2 mJy per beam). Also reported are 1.2-millimeter continuum and a series of molecular-line observations made with the SEST telescope. For IRAS 15596-5301, the observations reveal the presence of three distinct compact radio-continuum sources associated with a dense molecular core. We suggest that this core contains a cluster of B stars which are exciting compact HII regions that are in pressure equilibrium with the dense molecular surroundings. No radio continuum emission was detected from IRAS 16272-4837 (3-sigma limit of 0.2 mJy). However, a dense molecular core has been detected. The high luminosity and lack of radio emission from this massive core suggests that it hosts an embedded young massive protostar that is still undergoing an intense accretion phase. This scenario is supported by the observed characteristics of the line profiles and the presence of a bipolar outflow detected from observations of the SiO emission. We suggest that IRAS 16272-4837 is a bona fide massive star- forming region in a very early evolutionary stage, being the precursor of an ultra compact HII region.Comment: 25 pages, 9 figures, accepted for publication in The Astrophysical Journa

High-Mass Proto-Stellar Candidates - I : The Sample and Initial Results

We describe a systematic program aimed at identifying and characterizing candidate high-mass proto-stellar objects (HMPOs). Our candidate sample consists of 69 objects selected by criteria based on those established by Ramesh & Sridharan (1997) using far-infrared, radio-continuum and molecular line data. Infrared-Astronomical-Satellite (IRAS) and Midcourse-Space-Experiment (MSX) data were used to study the larger scale environments of the candidate sources and to determine their total luminosities and dust temperatures. To derive the physical and chemical properties of our target regions, we observed continuum and spectral line radiation at millimeter and radio wavelengths. We imaged the free-free and dust continuum emission at wavelengths of 3.6 cm and 1.2 mm, respectively, searched for H2O and CH3OH maser emission and observed the CO 2-1 and several NH3 lines toward all sources in our sample. Other molecular tracers were observed in a subsample. The presented results indicate that a substantial fraction of our sample harbors HMPOs in a pre-UCHII region phase, the earliest known stage in the high-mass star formation process.Comment: 16 pages, 11 eps-figures. Astrophysical Journal, in pres

Formation of massive stars by growing accretion rate

We perform calculations of pre-main sequence evolution of stars from 1 to $85 M_{\odot}$ with growing accretion rates $\dot{M}$. The values of $\dot{M}$ are taken equal to a constant fraction $\tilde{f}$ of the rates of the mass outflows observed by Churchwell (\cite{church}) and Henning (\cite{henning2000}). The evolution of the various stellar parameters is given, as well as the evolution of the disc luminosity; electronic tables are provided as a supplement to the articles. Typically, the duration of the accretion phase of massive stars is $\simeq 3 \cdot 10^5$yr. and there is less than 10% difference in the time necessary to form a 8 or $80 M_{\odot}$ star. If in a young cluster all the proto-stellar cores start to accrete at the same time, we then have a relation $M(t)$ between the masses of the new stars and the time $t$ of their appearance. Since we also know the distribution of stellar masses at the end of star formation (IMF), we can derive the star formation history $N(t)$. Interestingly enough, the current IMF implies two peaks of star formation: low mass stars form first and high mass star form later

Sorption-desorption of Imidacloprid and its Metabolites in Soil and Vadose Zone Materials

Sorption-desorption is one of the most important processes affecting the leaching of pesticides through soil because it controls the amount of pesticide available for transport. Subsurface soil properties can significantly affect pesticide transport and the potential for groundwater contamination. This research characterized the sorption-desorption of imidacloprid (1-[(6-chloro-3-pyridinyl)-methyl]-Nnitro-2-imidazolidinimine) and three of its metabolites, 1-[(6-chloro-3-pyridinyl)methyl]-2-imidazolidinone (imidacloprid-urea), 1-[(6-chloro-3-pyridinyl)methyl]-4,5-dihydro-1H-imidazol-2-amine (imidaclopridguanidine), and 1-[(6-chloro-3-pyridinyl)methyl]-1H-imidazol-2-amine (imidacloprid-guanidine-olefin), as a function of changing soil properties with depth in two profiles extending from the surface to a depth of 1.8 or 8 m. Sorption of each compound was highly variable and hysteretic in all cases. Normalizing the sorption coefficients (Kf) to the organic carbon or the clay content of the soil did not reduce the variability in sorption coefficients for any compound. These results illustrate the importance of evaluation of the sorption data used to predict potential mobility. Understanding the variability of soil properties and processes as a function of depth is necessary for accurate prediction of pesticide dissipation