2,962 research outputs found

    Nantucket Pine Tip Moth (Lepidoptera: Tortricidae) Infestation Rates Related to Site and Stand Characteristics in Nacogdoches County, Texas

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    Twenty-two pine stands with a variety of site and stand characteristics and management strategies were analyzed using discriminant analysis to determine factors which influence Nantucket pine tip moth infestations. A whole-tree sequential sampling scheme designed to estimate absolute infestation rates (±5%) was used. An 8% infestation rate was used as the dividing line between high and low tip moth infestations. A sequential sampling program was used in the field to estimate populations. Absolute infestation rates (P ± 5%), were obtained through random selection of pines for whole-tree sampling. Four equations were developed which gave 91% correct classification of initial data. The discriminating variables included site preparation intensity, pine height, pine age, site index, soil texture at 61 cm depth, depth of A horizon multiplied by soil texture code, and depth of clay

    Clinical Development of New TB Vaccines: Recent Advances and Next Steps.

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    Mycobacterium tuberculosis (Mtb) kills more people worldwide than any single infectious pathogen, yet the only vaccine licensed against tuberculosis, Bacille Calmette Guerin (BCG) is approaching its centenary. Two recent advances in clinical tuberculosis vaccine development have invigorated the field. BCG revaccination of interferon-gamma release assay (IGRA) negative adolescents provided 45% protection against sustained Mtb infection defined by IGRA conversion; and the protein-subunit vaccine M72/AS01 E provided 50% protection against progression from Mtb infection to tuberculosis disease in IGRA-positive adults. These findings provide encouraging evidence for pre-exposure and post-exposure approaches to vaccination against tuberculosis, both of which may be necessary to rapidly interrupt the cycle of Mtb transmission and sustain long-term impact on global tuberculosis control. New trials are needed to demonstrate efficacy of M72/AS01 E with greater precision, in a wider age range, in diverse epidemic settings, and in populations that include Mtb-uninfected and HIV-infected persons. Modeling the impact of mass campaigns with M72/AS01 E and other fast-follower vaccine candidates will be crucial to make the use case and demonstrate public health value for TB endemic countries. The size and scope of the next generation of efficacy trials, and the need to expand and accelerate the existing clinical development pipeline, will require public and private consortium funding and concerted political will

    The demand for public transport: The effects of fares, quality of service, income and car ownership

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    This paper reports on key findings from a collaborative study whose objective was to produce an up-to-date guidance manual on the factors affecting the demand for public transport for use by public transport operators and planning authorities, and for academics and other researchers. Whilst a wide range of factors was examined in the study, the paper concentrates on the findings regarding the influence of fares, quality of service and income and car ownership. The results are a distillation and synthesis of identified published and unpublished information on the factors affecting public transport demand. The context is principally that of urban surface transport in Great Britain, but extensive use was made in the study of international sources and examples

    Guest Editorial

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    A novel blood test for tuberculosis prevention and treatmen

    Discovery of a Classic FR-II Broad Absorption Line Quasar from the FIRST Survey

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    We have discovered a remarkable quasar, FIRST J101614.3+520916, whose optical spectrum shows unambiguous broad absorption features while its double-lobed radio morphology and luminosity clearly indicate a classic Fanaroff-Riley Type II radio source. Its radio luminosity places it at the extreme of the recently established class of radio-loud broad absorption line quasars (Becker et al. 1997, 2000; Brotherton et al. 1998). Because of its hybrid nature, we speculate that FIRST J101614.3+520916 is a typical FR-II quasar which has been rejuvenated as a broad absorption line (BAL) quasar with a Compact Steep Spectrum core. The direction of the jet axis of FIRST J101614.3+520916 can be estimated from its radio structure and optical brightness, indicating that we are viewing the system at a viewing angle of > 40 degrees. The position angles of the radio jet and optical polarization are not well-aligned, differing by 20 to 30 degrees. When combined with the evidence presented by Becker et al. (2000) for a sample of 29 BAL quasars showing that at least some BAL quasars are viewed along the jet axis, the implication is that no preferred viewing orientation is necessary to observe BAL systems in a quasar's spectrum. This, and the probable young nature of compact steep spectrum sources, leads naturally to the alternate hypothesis that BALs are an early stage in the lives of quasars.Comment: 14 pages, 6 postscript figures; accepted for publication in the Astrophysical Journa

    Imaging and spectroscopy of galaxies associated with two z~0.7 damped Lyman-alpha absorption systems

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    We have identified galaxies near two quasars which are at the redshift of damped Lyman-alpha (DLA) systems in the UV spectra of the quasars. Both galaxies are actively forming stars. One galaxy has a luminosity close to the break in the local galaxy luminosity function, L*, the other is significantly fainter than L* and appears to be interacting with a nearby companion. Despite the strong selection effects favoring spectroscopic identification of the most luminous DLA galaxies, many of the spectroscopically-identified DLA galaxies in the literature are sub-L*, suggesting that the majority of the DLA population is probably sub-L*, in contrast to MgII absorbers at similar redshifts whose mean luminosity is close to L*.Comment: 9 pages, to appear in AJ, November 2003 issu

    A catalog of Nearby Poor Clusters of Galaxies

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    A catalog of 732 optically selected, nearby poor clusters of galaxies covering the entire sky north of 3\rm -3^{\circ} declination is presented. The poor clusters, called WBL clusters, were identified as concentrations of 3 or more galaxies with photographic magnitudes brighter than 15.7, possessing a galaxy surface overdensity of 104/310^{4/3}. These criteria are consistent with those used in the identification of the original Yerkes poor clusters, and this new catalog substantially increases the sample size of such objects. These poor clusters cover the entire range of galaxy associations up to and including Abell clusters, systematically including poor and rich galaxy systems spanning over three orders of magnitude in the cluster mass function. As a result, this new catalog contains a greater diversity of richness and structures than other group catalogs, such as the Hickson or Yerkes catalogs. The information on individual galaxies includes redshifts and cross-references to other galaxy catalogs. The entries for the clusters include redshift (where available) and cross-references to other group and cluster catalogs.Comment: 27 pages, 7 figures, + one 20-page landscape table, accepted for publication in A

    Nuclear fusion during yeast mating occurs by a three-step pathway

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    In Saccharomyces cerevisiae, mating culminates in nuclear fusion to produce a diploid zygote. Two models for nuclear fusion have been proposed: a one-step model in which the outer and inner nuclear membranes and the spindle pole bodies (SPBs) fuse simultaneously and a three-step model in which the three events occur separately. To differentiate between these models, we used electron tomography and time-lapse light microscopy of early stage wild-type zygotes. We observe two distinct SPBs in ∼80% of zygotes that contain fused nuclei, whereas we only see fused or partially fused SPBs in zygotes in which the site of nuclear envelope (NE) fusion is already dilated. This demonstrates that SPB fusion occurs after NE fusion. Time-lapse microscopy of zygotes containing fluorescent protein tags that localize to either the NE lumen or the nucleoplasm demonstrates that outer membrane fusion precedes inner membrane fusion. We conclude that nuclear fusion occurs by a three-step pathway
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