A Merger Scenario for the Dynamics of Abell 665

We present new redshift measurements for 55 galaxies in the vicinity of the rich galaxy cluster Abell 665. When combined with results from the literature, we have good velocity measurements for a sample of 77 confirmed cluster members from which we derive the cluster's redshift z=0.1829 +/- 0.0005 and line-of-sight velocity dispersion of 1390 +/- 120 km/s. Our analysis of the kinematical and spatial data for the subset of galaxies located within the central 750 kpc reveals only subtle evidence for substructure and non-Gaussianity in the velocity distribution. We find that the brightest cluster member is not moving significantly relative to the other galaxies near the center of the cluster. On the other hand, our deep ROSAT high resolution image of A665 shows strong evidence for isophotal twisting and centroid variation, thereby confirming previous suggestions of significant substructure in the hot X-ray--emitting intracluster gas. In light of this evident substructure, we have compared the optical velocity data with N-body simulations of head-on cluster mergers. We find that a merger of two similar mass subclusters (mass ratios of 1:1 or 1:2) seen close to the time of core-crossing produces velocity distributions that are consistent with that observed.Comment: 30 pages and 7 figures. Accepted by the Astrophysical Journal Full resoultion figures 1 and 3 available in postscript at http://www.physics.rutgers.edu/~percy/A665paper.htm

The Effect of In Vitro Cultivation on the Transcriptome of Adult Brugia malayi

Infections with filarial worms cause serious physical impairment and affect tens of millions of people in tropical and subtropical countries. To better understand the biology and phar- macology of these parasites, Brugia malayi is often used as a model. This parasite can be maintained in the laboratory in Mongolian jirds, enabling researchers to test drugs in vivoand in vitro, among other studies. The effects of removing worms from their hosts and cul- turing them may affect many aspects of their physiology, including response to drugs, but the extent to which the worms undergo changes during culture has remained unknown. Using deep RNA sequencing and bioinformatics tools, we examined the global transcriptomic profile of B. malayi females at four different time points over 5 days in culture. Focusing on genes that are differentially expressed at various time points, we observed a general perturbation of the expression profile between dissection from the host and receipt after shipment. The expression of several genes remained changed at the end of the experi- ment, after 5 days under controlled conditions; in particular, genes encoding cuticle colla- gens were prominently represented and strongly overexpressed

The Effects of Ivermectin on Brugia malayi Females In Vitro: A Transcriptomic Approach

Lymphatic filariasis and onchocerciasis are tropical diseases caused by infections with parasitic nematodes. Resulting chronic diseases can be strongly blinding and disfiguring, and contribute to an entrenched cycle of poverty in affected populations. Ivermectin is one of the pivotal drugs used to control these infections. The mechanism of antifilarial action of the drug is incompletely resolved. It kills circulating larval stages (microfilariae), but only reversibly sterilizes adult worms without killing them. Our limited understanding of the involved mechanisms hampers treatment optimization and sustainability of the efficacy of the drug, and investigations into its pharmacology are of paramount importance. Working with Brugia malayi adult females, we employed RNA sequencing and bioinformatics analyses to identify genes for which expression levels changed as a result of exposure to the drug in vitro. Ivermectin exposure altered the expression of genes that are likely to func- tion in the B. malayi female reproductive system even at the lowest concentration tested. Through several biological pathways, genes involved in meiosis were particularly affected. These findings provide some insight into the mechanisms involved in ivermectin-induced reduction in microfilaria output and impaired fertility, embryogenesis, and larval development

Hectospec, the MMT's 300 Optical Fiber-Fed Spectrograph

The Hectospec is a 300 optical fiber fed spectrograph commissioned at the MMT in the spring of 2004. A pair of high-speed six-axis robots move the 300 fiber buttons between observing configurations within ~300 s and to an accuracy ~25 microns. The optical fibers run for 26 m between the MMT's focal surface and the bench spectrograph operating at R~1000-2000. Another high dispersion bench spectrograph offering R~5,000, Hectochelle, is also available. The system throughput, including all losses in the telescope optics, fibers, and spectrograph peaks at ~10% at the grating blaze in 1" FWHM seeing. Correcting for aperture losses at the 1.5" diameter fiber entrance aperture, the system throughput peaks at $\sim$17%. Hectospec has proven to be a workhorse instrument at the MMT. Hectospec and Hectochelle together were scheduled for 1/3 of the available nights since its commissioning. Hectospec has returned \~60,000 reduced spectra for 16 scientific programs during its first year of operation.Comment: 68 pages, 28 figures, to appear in December 2005 PAS

A quantitative assessment of shoot flammability for 60 tree and shrub species supports rankings based on expert opinion

Fire is an important ecological disturbance in vegetated ecosystems across the globe, and also has considerable impacts on human infrastructure. Vegetation flammability is a key bottom-up control on fire regimes, and on the nature of individual fires. Although New Zealand (NZ) historically had low fire frequencies, anthropogenic fires have considerably impacted indigenous vegetation as humans used fire extensively to clear forests. Few studies of vegetation flammability have been undertaken in NZ, and only one has compared the flammability of indigenous plants; this was a qualitative assessment derived from expert opinion. We addressed this knowledge gap by measuring the flammability of terminal shoots from a range of trees and shrubs found in NZ. We quantified shoot flammability of 60 indigenous and exotic species, and compared our experimentally derived ranking with expert opinion. The most flammable species was the invasive exotic shrub Ulex europaeus, followed by Eucalyptus viminalis, Pomaderris kumeraho, Dacrydium cupressinum, and Lophozonia menziesii. Our experimentally derived ranking was strongly correlated with expert opinion, lending support to both methods. Our results are useful to ecologists seeking to understand how fires have and will influence NZ’s ecosystems, and for fire managers identifying high-risk landscapes, and low flammability species for ‘green firebreaks’