An updated maximum likelihood approach to open cluster distance determination

An improved method for estimating distances to open clusters is presented and applied to Hipparcos data for the Pleiades and the Hyades. The method is applied in the context of the historic Pleiades distance problem, with a discussion of previous criticisms of Hipparcos parallaxes. This is followed by an outlook for Gaia, where the improved method could be especially useful. Based on maximum likelihood estimation, the method combines parallax, position, apparent magnitude, colour, proper motion, and radial velocity information to estimate the parameters describing an open cluster precisely and without bias. We find the distance to the Pleiades to be $120.3 \pm 1.5$ pc, in accordance with previously published work using the same dataset. We find that error correlations cannot be responsible for the still present discrepancy between Hipparcos and photometric methods. Additionally, the three-dimensional space velocity and physical structure of Pleiades is parametrised, where we find strong evidence of mass segregation. The distance to the Hyades is found to be $46.35\pm 0.35$ pc, also in accordance with previous results. Through the use of simulations, we confirm that the method is unbiased, so will be useful for accurate open cluster parameter estimation with Gaia at distances up to several thousand parsec.Comment: 14 pages, 8 figures, 6 tables, 3 appendices. Accepted in A&

Impermissibility of Impersonal Harm: Impersonal Harm, Social Values, and Genetic Enhancement

https://openworks.mdanderson.org/sumexp22/1110/thumbnail.jp

Variacions estacionals de l'abundància dels tenebriònids (Coleoptera, Tenebrionidae) a l'illa del Toro (Calvià, Mallorca)

Abstract not availabl

Research Notes : United States : Inheritance of a miniature mutant in soybean

Mutant T251 was found by Dr. R. L. Bernard at the University of Illinois in an F2 progeny from the cross \u27Harosoy\u275xT139. (Tl39 is a yellow mutant found in \u27Illini\u27 in 1936.) T251 is maintained in the Soybean Genetic Type Collection as the heterozygote T251H because of its low seed set. It is char-acterized by its short and slender stature

Modeling of a Cantilever-Based Near-Field Scanning Microwave Microscope

We present a detailed modeling and characterization of our scalable microwave nanoprobe, which is a micro-fabricated cantilever-based scanning microwave probe with separated excitation and sensing electrodes. Using finite-element analysis, the tip-sample interaction is modeled as small impedance changes between the tip electrode and the ground at our working frequencies near 1GHz. The equivalent lumped elements of the cantilever can be determined by transmission line simulation of the matching network, which routes the cantilever signals to 50 Ohm feed lines. In the microwave electronics, the background common-mode signal is cancelled before the amplifier stage so that high sensitivity (below 1 atto-Farad capacitance changes) is obtained. Experimental characterization of the microwave probes was performed on ion-implanted Si wafers and patterned semiconductor samples. Pure electrical or topographical signals can be realized using different reflection modes of the probe.Comment: 7 figure

Invertebrats endèmics i illes: (Tenebrionidae i Araneae) introduccions i extincions als illots de Cabrera (Illes Balears)

S'analitza la composició faunística dels illots de Cabrera per avaluar si hi ha diferències en l'impacte que ha tingut un esdeveniment històric clau (la colonització per Rattus rattus) sobre dos grups faunístics amb capacitat de dispersió ben contrastada: les aranyes en front als coleòpters tenebrionids. Es confirma l'existència de diferències significatives en quant a la composició taxonòmica i estructura de les comunitats per als dos grups, i s'interpreten aquestes diferències dintre d'un marc teòric general. Es proposa que, com a norma general, la composició d'espècies endèmiques (com a paradigma de les espècies males dispersores) a illes no oceàniques serà el resultat de successives extincions a partir d'un stock inicial més ric, degudes a l'impacte de diferents esdeveniments claus que van tenint lloc al llarg de la història de cada illa.The faunistic composition of 14 islets from the Cabrera archipelago (off SE Mallorca, Balearic Is.) is analysed in search of potential differences in both composition and structure of the community of two invertebrate groups displaying contrasting dispersal capabilities: spiders versus tenebrionid beetles. Differences found are explained as the result of a historical event: the introduction of Rattus rattus. We propose that the current composition of endemic species in non-oceanic islands must be envisaged as the result of successive extinction events, each linked to specific key events having occurred during island history. It is assumed that the number of endemic species diminishes with time from a larger initial stock. Insular endemic species are a paradigmatic example of organisms with very reduced potencial for dispersal. Therefore, the introduced model of successive extinctions can be applicable to every poorly dispersed group of organisms

In Memoriam Francesc Español (1907-1999)

Abstract not availabl

Resolving The ISM Surrounding GRBs with Afterglow Spectroscopy

We review current research related to spectroscopy of gamma-ray burst (GRB) afterglows with particular emphasis on the interstellar medium (ISM) of the galaxies hosting these high redshift events. These studies reveal the physical conditions of star-forming galaxies and yield clues to the nature of the GRB progenitor. We offer a pedagogical review of the experimental design and review current results. The majority of sightlines are characterized by large HI column densities, negligible molecular fraction, the ubiquitous detection of UV pumped fine-structure transitions, and metallicities ranging from 1/100 to nearly solar abundance.Comment: Conference procedings for Gamma Ray Bursts 2007 November 5-9, 2007 Santa Fe, New Mexico (8 pages, 4 figures

Staphylinidae y Pselaphidae (Coleoptera, Staphylinoidea) de s'Albufera de Mallorca (Islas Baleares)

Abstract not availabl

Research Notes : United States : Linkage group 12

Weiss (1970a, b, c, d, e) described linkage groups 1 to 7 in soybean. Buzzell (1974, 1979) and Palmer (1977, 1984) have characterized further link-age group 1. Linkage group 8 was reported by Buzzell et al. (1977) and described further by Palmer and Kaul (1983), Sadanaga (1983) and Sadanaga and Grindeland (1984)