Howard University in the War

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Genomic integration of transgenes using UV irradiation in Pristionchus pacificus

Transgenes are widely used throughout molecular biology for numerous applications. In Caenorhabditis elegans, stable transgenes are usually generated by microinjection into the germline establishing extrachromosomal arrays. Furthermore, numerous technologies exist to integrate transgenes into the C. elegans genome. In the nematode Pristionchus pacificus, transgenes are possible, however, their establishment is less efficient and dependent on the formation of complex arrays containing the transgene of interest and host carrier DNA. Additionally, genomic integration has only been reported via biolistic methods. Here we describe a simple technique using UV irradiation to facilitate the integration of transgenes into the P. pacificus genome

HST/ACS Images of the GG Tauri Circumbinary Disk

Hubble Space Telescope Advanced Camera for Surveys images of the young binary GG Tauri and its circumbinary disk in V and I bandpasses were obtained in 2002 and are the most detailed of this system to date. The confirm features previously seen in the disk including: a "gap" apparently caused by shadowing from circumstellar material; an asymmetrical distribution of light about the line of sight on the near edge of the disk; enhanced brightness along the near edge of the disk due to forward scattering; and a compact reflection nebula near the secondary star. New features are seen in the ACS images: two short filaments along the disk; localized but strong variations in disk intensity ("gaplets"); and a "spur" or filament extending from the reflection nebulosity near the secondary. The back side of the disk is detected in the V band for the first time. The disk appears redder than the combined light from the stars, which may be explained by a varied distribution of grain sizes. The brightness asymmetries along the disk suggest that it is asymmetrically illuminated by the stars due to extinction by nonuniform circumstellar material or the illuminated surface of the disk is warped by tidal effects (or perhaps both). Localized, time-dependent brightness variations in the disk are also seen.Comment: 28 pages, 7 figures, accepted for publication in the Astronomical Journa

Cultures in Contact at Colony Ross

For thousands of years before the coming of Europeans, Kashaya Pomo and Coast Miwok peoples inhabited the coastal lands north of San Francisco Bay. Like many other California Indians, they were hunter-gatherers who harvested wild plants and animals from the sea and land for food, medicine, clothing, housing material, and ceremonial regalia. Villages nestled along protected coastal embayments and ridge tops of the Northern Coast Ranges mountains contained tule-thatched or redwood bark houses, ceremonial structures (round houses), sweat houses, dance enclosures, and extramural cooking and work areas. Large villages served as the political centers for broader communities of dispersed family groups who would come together for periodic dances, ceremonies, initiation rites, and feasts. With the founding of Colony Ross in 1812 by the Russian-American Company (RAC), a mercantile enterprise licensed by the tsar of Russia, life would change forever for the Kashaya Pomo and the Coast Miwok. The Russian merchants placed the primary administrative center of the colony, which they called the Ross settlement, in the heart of Kashaya Pomo territory, and they chose Bodega Harbor in Coast Miwok country to be the principal port facility (Port Rumiantsev) (Figure 7.15). The Russian-American Company came to California to profit from the exploitation of the region\u27s natural bounty. The mercantile enterprise harvested sea mammals, primarily sea otters and fur seals, to fuel the lucrative maritime fur trade that supplied sea mammal pelts to China, Europe, and the United States, primarily for use as robes, fur trim, and other clothing accessories. The Russian merchants attempted to grow wheat, barley, and other crops, and to raise livestock at Colony Ross to feed other RAC colonies in the North Pacific (Aleutian Islands, Kodiak Island, Prince William Sound, etc.), which experienced periodic food shortages. The Ross settlement also served as a manufacturing center for the production of goods (timber, bricks, metal utensils, and tools) that were shipped to the other North Pacific colonies and also traded to the Franciscan missionaries in Alta California for foodstuffs grown in the extensive mission complexes

Evolution and diversity of TGF-beta pathways are linked with novel developmental and behavioural trait

Transforming growth factor β (TGF-β) signalling is essential for numerous biological functions. It is a highly conserved pathway found in all metazoans including the nematode Caenorhabditis elegans, which has also been pivotal in identifying many components. Utilising a comparative evolutionary approach, we explored TGF-β signalling in nine nematode species and revealed striking variability in TGF-β gene frequency across the lineage. Of the species analysed, gene duplications in the DAF-7 pathway appear common with the greatest disparity observed in Pristionchus pacificus. Specifically, multiple paralogues of daf-3, daf-4 and daf-7 were detected. To investigate this additional diversity, we induced mutations in 22 TGF-β components and generated corresponding double, triple and quadruple mutants revealing both conservation and diversification in function. Although, the DBL-1 pathway regulating body morphology appears highly conserved, the DAF-7 pathway exhibits functional divergence, notably in some aspects of dauer formation. Furthermore, the formation of the phenotypically plastic mouth in P. pacificus is partially influenced through TGF-β with the strongest effect in Ppa-tag-68. This appears important for numerous processes in P. pacificus but has no known function in C. elegans. Finally, we observe behavioural differences in TGF-β mutants including in chemosensation and the establishment of the P. pacificus kin-recognition signal. Thus, TGF-β signalling in nematodes represents a stochastic genetic network capable of generating novel functions through the duplication and deletion of associated genes

Sex or cannibalism: Polyphenism and kin recognition control social action strategies in nematodes

Resource polyphenisms, where single genotypes produce alternative feeding strategies in response to changing environments, are thought to be facilitators of evolutionary novelty. However, understanding the interplay between environment, morphology, and behavior and its significance is complex. We explore a radiation of Pristionchus nematodes with discrete polyphenic mouth forms and associated microbivorous versus cannibalistic traits. Notably, comparing 29 Pristionchus species reveals that reproductive mode strongly correlates with mouth-form plasticity. Male-female species exhibit the microbivorous morph and avoid parent-offspring conflict as indicated by genetic hybrids. In contrast, hermaphroditic species display cannibalistic morphs encouraging competition. Testing predation between 36 co-occurring strains of the hermaphrodite P. pacificus showed that killing inversely correlates with genomic relatedness. These empirical data together with theory reveal that polyphenism (plasticity), kin recognition, and relatedness are three major factors that shape cannibalistic behaviors. Thus, developmental plasticity influences cooperative versus competitive social action strategies in diverse animals

Spitzer IRAC Observations of Star Formation in N159 in the LMC

We present observations of the giant HII region complex N159 in the LMC using IRAC on the {\it Spitzer Space Telescope}. One of the two objects previously identified as protostars in N159 has an SED consistent with classification as a Class I young stellar object (YSO) and the other is probably a Class I YSO as well, making these two stars the youngest stars known outside the Milky Way. We identify two other sources that may also be Class I YSOs. One component, N159AN, is completely hidden at optical wavelengths, but is very prominent in the infrared. The integrated luminosity of the entire complex is L $\approx 9\times10^6$L$_{\odot}$, consistent with the observed radio emission assuming a normal Galactic initial mass function (IMF). There is no evidence for a red supergiant population indicative of an older burst of star formation. The N159 complex is 50 pc in diameter, larger in physical size than typical HII regions in the Milky Way with comparable luminosity. We argue that all of the individual components are related in their star formation history. The morphology of the region is consistent with a wind blown bubble $\approx 1-2Myr-old that has initiated star formation now taking place at the rim. Other than its large physical size, star formation in N159 appears to be indistinguishable from star formation in the Milky Way.Comment: 14 figure

State-of-the-art in integrated vehicle health management

Integrated vehicle health management (IVHM) is a collection of data relevant to the present and future performance of a vehicle system and its transformation into information can be used to support operational decisions. This design and operation concept embraces an integration of sensors, communication technologies, and artificial intelligence to provide vehicle-wide abilities to diagnose problems and recommend solutions. This article aims to report the state-of-the-art of IVHM research by presenting a systematic review of the literature. The literature from different sources is collated and analysed, and the major emerging themes are presented. On this basis, the article describes the IVHM concept and its evolution, discusses configurations and existing applications along with main drivers, potential benefits and barriers to adoption, summarizes design guidelines and available methods, and identifies future research challenges

HARP/ACSIS: A submillimetre spectral imaging system on the James Clerk Maxwell Telescope

This paper describes a new Heterodyne Array Receiver Programme (HARP) and Auto-Correlation Spectral Imaging System (ACSIS) that have recently been installed and commissioned on the James Clerk Maxwell Telescope (JCMT). The 16-element focal-plane array receiver, operating in the submillimetre from 325 to 375 GHz, offers high (three-dimensional) mapping speeds, along with significant improvements over single-detector counterparts in calibration and image quality. Receiver temperatures are $\sim$120 K across the whole band and system temperatures of $\sim$300K are reached routinely under good weather conditions. The system includes a single-sideband filter so these are SSB figures. Used in conjunction with ACSIS, the system can produce large-scale maps rapidly, in one or more frequency settings, at high spatial and spectral resolution. Fully-sampled maps of size 1 square degree can be observed in under 1 hour. The scientific need for array receivers arises from the requirement for programmes to study samples of objects of statistically significant size, in large-scale unbiased surveys of galactic and extra-galactic regions. Along with morphological information, the new spectral imaging system can be used to study the physical and chemical properties of regions of interest. Its three-dimensional imaging capabilities are critical for research into turbulence and dynamics. In addition, HARP/ACSIS will provide highly complementary science programmes to wide-field continuum studies, and produce the essential preparatory work for submillimetre interferometers such as the SMA and ALMA.Comment: MNRAS Accepted 2009 July 2. 18 pages, 25 figures and 6 table

Coupling to optical phonons in the one-dimensional t-J model: Effects on superconducting fluctuations and phase separation

The one-dimensional (1D) $t$-$J$ Holstein model is studied by exact diagonalization of finite rings using a variational approximation for the phonon states. Due to renormalization effects induced by the phonons, for intermediate electron-phonon coupling, the phase separation (PS) boundary, and with it the region of dominating superconducting fluctuations is shifted substantially to smaller values of $J/t$ as compared to the pure $t$-$J$ model. Superconducting correlations are weakened through charge density wave interactions mediated by the phonons. Possible consequences for the high $T_c$ oxides are discussed.Comment: 4 pages, Latex2