Between-Site Variation in Suitability of \u3ci\u3eSalix Cordata\u3c/i\u3e as a Host for \u3ci\u3eAltica Subplicata\u3c/i\u3e (Coleoptera: Chrysomelidae)

To investigate local adaptation of insect herbivore populations to host plant populations, willow flea beetles (Altica subplicata) were collected from two distant sites in northern Michigan (Grass Bay, GB; Pte. Aux Chenes, PAC) and reared on host plants (Salix cordata) collected from each of the sites. Larval development (measured by molt frequency and length of larval stage) was significantly faster on PAC plants than on GB plants but did not differ for the two beetle populations. For both populations of beetles, mean pupal weight was also greater on PAC plants than on GB plants. Thus, there was no evidence for adaptation of beetle populations to local host plant populations. The greater performance of A. subplicata on PAC plants most likely resulted from a lower trichome density on leaves of plants from that site

Focus drive mechanism for the IUE scientific instrument

A compact, lightweight mechanism was developed for in-orbit adjustment of the position of the secondary mirror (focusing) of the International Ultraviolet Explored telescope. This device is a linear drive with small (.0004 in.) and highly repeatable step increments. Extremely close tolerances are also held in tilt and decentering. The unique mechanization is described with attention to the design details that contribute to positional accuracy. Lubrication, materials, thermal considerations, sealing, detenting against launch loads, and other features peculiar to flight hardware are discussed. The methods employed for mounting the low expansion quartz mirror with minimum distortion are also given

Recording and wear characteristics of 4 and 8 mm helical scan tapes

Performance data of media on helical scan tape systems (4 and 8 mm) is presented and various types of media are compared. All measurements were performed on a standard MediaLogic model ML4500 Tape Evaluator System with a Flash Converter option for time based measurements. The 8 mm tapes are tested on an Exabyte 8200 drive and 4 mm tapes on an Archive Python drive; in both cases, the head transformer is directly connected to a Media Logic Read/Write circuit and test electronics. The drive functions only as a tape transport and its data recover circuits are not used. Signal to Noise, PW 50, Peak Shift and Wear Test data is used to compare the performance of MP (metal particle), BaFe, and metal evaporate (ME). ME tape is the clear winner in magnetic performance but its susceptibility to wear and corrosion, make it less than ideal for data storage

Distant Galaxy Clusters Identified From Optical Background Fluctuations

We present the first high redshift (0.3 < z < 1.1) galaxy clusters found by systematically identifying optical low surface brightness fluctuations in the background sky. Using spectra obtained with the Keck telescope and I-band images from the Palomar 1.5m telescope, we conclude that at least eight of the ten candidates examined are high redshift galaxy clusters. The identification of such clusters from low surface brightness fluctuations provides a complementary alternative to classic selection methods based on overdensities of resolved galaxies, and enables us to search efficiently for rich high redshift clusters over large areas of the sky. The detections described here are the first in a survey that covers a total of nearly 140 sq. degrees of the sky and should yield, if these preliminary results are representative, over 300 such clusters.Comment: Submitted to ApJ

CO excitation in four IR luminous galaxies

The correlation between the CO and far infrared luminosities of spiral galaxies is well established. The luminosity ration, L sub FIR/L sub CO in IR luminous active galaxies is, however, systematically five to ten times higher than in ordinary spirals and molecular clouds in our Galaxy. Furthermore, the masses of molecular hydrogen in luminous galaxies are large, M (H2) approx. equals 10(exp 10) solar magnitude, which indicates the observed luminosity ratios are due to an excess of infrared output, rather than a deficiency of molecular gas. These large amounts of molecular gas may fuel luminous galaxies through either star formation or nuclear activity. This interpretation rests on applying the M (H2)/L sub CO ratio calibrated in our Galaxy to galaxies with strikingly different luminosity ratios. But are the physical conditions of the molecular gas different in galaxies with different luminosity ratios. And, if so, does the proportionality between CO and H2 also vary among galaxies. To investigate these questions researchers observed CO (2 to 1) and (1 to 0) emission from four luminous galaxies with the Institute for Radio Astronomy in the Millimeter range (IRAM) 30 m telescope. Researchers conclude that most of the CO emission from these Arp 193, Arp 220, and Mrk 231 arises in regions with moderate ambient densities similar to the clouds in the Milky Way molecular ring. The emission is neither from dense hot cloud cores nor from the cold low density gas characteristic of the envelopes of dark clouds

Leech Parasitism of the Gulf Coast Box Turtle, Terrapene carolina major (Testudines:Emydidae) in Mississippi, USA

Ten leeches were collected from a Gulf Coast box turtle, Terrapene carolina major, found crossing a road in Gulfport, Harrison County, Mississippi, USA. Eight of the leeches were identified as Placobdella multilineata and 2 were identified as Helobdella europaea. This represents the second vouchered report of leeches from a box turtle. Helobdella europaea is reported for the first time associated with a turtle and for the second time from the New World