Global Properties of Multiple Merger Remnants

Merger remnants of small groups of galaxies are contrasted with relics of mergers of pairs of galaxies to determine which process produces objects that best compare to real ellipticals. In both cases, the progenitors consist of self-gravitating disks, halos, and, sometimes, bulges. Pairs of galaxies merge from orbits that initially have zero--energy. The systems that produce multiple merger remnants are dense, six--member groups in virial equilibrium with low velocity dispersions. Multiple and pair mergers produce remnants which differ in both their spatial and kinematic properties. Multiple merger remnants have small triaxialities and are most likely to appear nearly round from most viewing angles. They possess cores, with sizes of a few tenths of an effective radius, that are more extended than pair remnant cores, even when bulges are included in the progenitors. In multiple mergers, the spin of all components -- halo, disk, and bulge -- increases and, while velocity dispersion dominates in the central regions, $v_r/\sigma \approx 1$ outside an effective radius in some projections. The angular momentum and minor axis vectors are aligned for multiple merger remnants. During merging of multiple progenitors, about half of the orbital angular momentum in each luminous component is converted into internal rotation in that component. Material is prevented from accumulating in the center of multiple merger remnants as efficiently as it does in pair mergers. In pair mergers that include gas, unrealistically steep surface brightness profiles have been produced in center of the remnants; in multiple mergers the formation of overdense nuclei may be impeded, thus allowing more successful comparison with real elliptical galaxies.Comment: 43 pages of uuencoded compressed postscript with 17 figures. Postscript figures 1,2,3,17, 3Mb total, available upon request from [email protected]. Accepted to the Astrophysical Journa

Gas distribution and starbursts in shell galaxies

Detailed maps of most elliptical galaxies reveal that, whereas the greatest part of their luminous mass originates from a smooth distribution with a surface brightness approximated by a de Vaucouleurs law, a small percentage of their light is contributed by low surface brightness distortions termed 'fine structures'. The sharp-edged features called 'shells' are successfully reproduced by merger and infall models involving accretion from less massive companions. In this context, dwarf spheroidal and compact disk galaxies are likely progenitors of these stellar phenomena. However, it is probable that the sources of shell-forming material also contain significant amounts of gas. This component may play an important role in constraining the formation and evolution of shell galaxies. To investigate the effects of the gaseous component, numerical simulations were performed to study the tidal disruption of dwarf galaxies containing both gas and stars by more massive primaries, and the evolution of the ensuing debris. The calculations were performed with a hybrid N-body/hydrodynamics code. Collisionless matter is evolved using a conventional N-body technique and gas is treated using smoothed particle hydrodynamics in which self-gravitating fluid elements are represented as particles evolving according to Lagrangian hydrodynamic equations. An isothermal equation of state is employed so the gas remains at a temperature 104 K. Owing to the large mass ratio between the primary and companion, the primary is modeled as a rigid potential and the self-gravity of both galaxies is neglected

Bundled Cable Parameters and Their Impact on EMI Measurement Repeatability

This research project was 99% experimental, therefore, not many theoretical ideas will be presented. The main idea behind the project was centered around cable bundling. The effect of cable bundling using analytical measurements and data from a network analyzer was investigated

Electric Service: The Next Generation

In the past few years,Maine\u27s electric utilities have begun to face the forces of competition.Maineis experiencing the effects of a national trend, a shift from a traditional and regulated system to a more innovative and competitive one. Gordon Weil, active inMaineand elsewhere in promoting increased competition in the electric industry, explains the forces for competition. He traces the history of the electric power market from its beginnings as a monopoly, to its present status where all of the forces promoting competition nationally are at play inMaine

Interview with Gordon Weil by Andrea L’Hommedieu

Biographical NoteGordon Lee Weil was born March 12, 1937, in Mineola, New York, and grew up on Long Island. Sadye, his mother, worked for the Red Cross and was chairman of nursing services in Nassau County and of the USO during World War II, and she served as state president of the National Council of Jewish Women. Gordon attended Hempstead High School and Bowdoin College, where he majored in history with a concentration in government. He was on the Agriculture Committee of the 1956 Democratic Party pre-convention platform committee in Maine and served as a page at the 1956 Democratic National Convention, Chicago. He worked in Washington, DC, with the European Common Market from 1963 to 1966. He also worked for the Washington Post and the Wall Street Journal. He is the author of The Long Shot, which chronicles his service as George McGovern’s executive assistant in 1971 and 1972 during McGovern’s presidential campaign. Weil was a Democratic State Convention delegate in 1974, was active in the George Mitchell 1974 gubernatorial election, and worked for Bill Clinton on his 1992 presidential campaign. He subsequently developed a legal expertise in power transmission and energy policy and regulation. SummaryInterview includes discussion of: becoming involved in the Democratic Party at Bowdoin; the Democratic National Convention in 1956; Muskie as chair of the Maine delegation; meeting George Mitchell in 1972 when he was campaigning to be the chair of the Democratic National Committee; Weil’s becoming part of the strategy group for Mitchell’s 1974 gubernatorial campaign and Mitchell’s strategy; Weil’s role in supporting Mitchell’s appointment to federal judge; Weil’s working for Joe Brennan; Ken Curtis; Arthur Stilphen’s relationship with Brennan; relationship between Joe Brennan and Mitchell; Mitchell’s speaking style; relationship between President Bill Clinton and George Mitchell; Clinton offering Mitchell an appointment to the Supreme Court; and Mitchell’s potential as a presidential candidate and career accomplishments

Site-selective protein modification via disulfide rebridging for fast tetrazine/trans-cyclooctene bioconjugation

An inverse electron demand Diels–Alder reaction between tetrazine and trans-cyclooctene (TCO) holds great promise for protein modification and manipulation. Herein, we report the design and synthesis of a tetrazine-based disulfide rebridging reagent, which allows the site-selective installation of a tetrazine group into disulfide-containing peptides and proteins such as the hormone somatostatin (SST) and the antigen binding fragment (Fab) of human immunoglobulin G (IgG). The fast and efficient conjugation of the tetrazine modified proteins with three different TCO-containing substrates to form a set of bioconjugates in a site-selective manner was successfully demonstrated for the first time. Homogeneous, well-defined bioconjugates were obtained underlining the great potential of our method for fast bioconjugation in emerging protein therapeutics. The formed bioconjugates were stable against glutathione and in serum, and they maintained their secondary structure. With this work, we broaden the scope of tetrazine chemistry for site-selective protein modification to prepare well-defined SST and Fab conjugates with preserved structures and good stability under biologically relevant conditions