571 research outputs found

    Titan's latitudinal temperature distribution and seasonal cycle

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    Voyager IRIS brightness temperature measurements of Titan at a wavelength of 530 cm^(−1) are crudely indicative of ground or lower tropospheric temperatures and indicate 93 K for the equator and 91 K for both northern and southern high latitudes. The symmetry between north and south is unexpected for the time of Voyager encounter (Northern Titan spring). We show that this near-symmetry can arise naturally in a model where the poles are "pinned" year-round at the dew point of CH_4-N_2 lakes or, more probably, a CH_4-N_2 rich surface layer on a deep ethane-rich ocean. For a polar temperature of 91 K, the model implies that the atmosphere contains somewhat less than 8% mole fraction of CH_4

    New bryophyte taxon records for tropical countries 1

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    This is the first in a series of papers listing new records, which will be published whenever sufficient new records have been found. The taxa are arranged by countries for an easier evaluation, e.g. updates of checklists. The initials of the contributor for each record is shown in square brackets after the record, and these initials are interpreted at the end of the paper

    Bryophytes of Uganda : 2., new and interesting records

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    51 hepatics and 46 mosses are reported new to Uganda, including one moss new to Africa, one hepatic and two mosses new to mainland Africa, and 2 hepatics that are otherwise known only from their type collection

    AssociationViewer: a scalable and integrated software tool for visualization of large-scale variation data in genomic context

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    Summary: We present a tool designed for visualization of large-scale genetic and genomic data exemplified by results from genome-wide association studies. This software provides an integrated framework to facilitate the interpretation of SNP association studies in genomic context. Gene annotations can be retrieved from Ensembl, linkage disequilibrium data downloaded from HapMap and custom data imported in BED or WIG format. AssociationViewer integrates functionalities that enable the aggregation or intersection of data tracks. It implements an efficient cache system and allows the display of several, very large-scale genomic datasets. Availability: The Java code for AssociationViewer is distributed under the GNU General Public Licence and has been tested on Microsoft Windows XP, MacOSX and GNU/Linux operating systems. It is available from the SourceForge repository. This also includes Java webstart, documentation and example datafiles. Contact: [email protected] Supplementary information: Supplementary data are available at http://sourceforge.net/projects/associationview/ onlin

    Factors affecting how children hear words and their relation to reading ability

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    Sensitivity to lexical stress has received attention recently as a predictor of reading skill. Six experiments explored the relationship between the reader's ability to process stress in spoken disyllabic nouns and verbs. In Experiments 1 and 2, adults and children identified disyllabic nouns and verbs, each involving trochaic and iambic instances, in "yes/no" and "go/nogo" auditory lexical decision tasks. The results showed that they processed lexical stress in the same manner, across both tasks, except children were slower. In Experiment 3, when children were presented with only iambic verbs and trochaic nouns in a verb/noun categorization task, poor readers were faster than good readers. Whereas Experiments 1 to 3 involved the presentation of a single spoken word on each trial, Experiments 4 to 6 all involved the presentation of spoken word pairs differing only in terms of stress (iambic verbs and trochaic nouns; e.g., reWARD and REward). Experiment 4 required children to decide whether the noun (or verb on 50% of trials) was first or last in the pair. Good and poor readers both showed no difference in response latencies, but did better at categorising iambic items. However, in Experiment 5, only good readers showed differences between identity (same) and contrastive (different) items in a same/different task. In Experiment 6, poor readers attended more to suprasegmentals, whereas good readers appeared to process the items at the segmental level in auditory priming lexical decision. Overall, the results showed that poor readers appear to attend more to acoustic/phonetic information in spoken word recognition, whereas the good readers attend to segmental information at the lexical level in spoken word recognition

    Rapid evolution of cancer/testis genes on the X chromosome

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    BACKGROUND: Cancer/testis (CT) genes are normally expressed only in germ cells, but can be activated in the cancer state. This unusual property, together with the finding that many CT proteins elicit an antigenic response in cancer patients, has established a role for this class of genes as targets in immunotherapy regimes. Many families of CT genes have been identified in the human genome, but their biological function for the most part remains unclear. While it has been shown that some CT genes are under diversifying selection, this question has not been addressed before for the class as a whole. RESULTS: To shed more light on this interesting group of genes, we exploited the generation of a draft chimpanzee (Pan troglodytes) genomic sequence to examine CT genes in an organism that is closely related to human, and generated a high-quality, manually curated set of human:chimpanzee CT gene alignments. We find that the chimpanzee genome contains homologues to most of the human CT families, and that the genes are located on the same chromosome and at a similar copy number to those in human. Comparison of putative human:chimpanzee orthologues indicates that CT genes located on chromosome X are diverging faster and are undergoing stronger diversifying selection than those on the autosomes or than a set of control genes on either chromosome X or autosomes. CONCLUSION: Given their high level of diversifying selection, we suggest that CT genes are primarily responsible for the observed rapid evolution of protein-coding genes on the X chromosome

    How U.S. Ocean Policy and Market Power Can Reform the Coral Reef Wildlife Trade

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    As the world’s largest importer of marine ornamental species for the aquaria, curio, home décor, and jewelry industries, the United States has an opportunity to leverage its considerable market power to promote more sustainable trade and reduce the effects of ornamental trade stress on coral reefs worldwide. Evidence indicates that collection of some coral reef animals for these trades has caused virtual elimination of local populations, major changes in age structure, and promotion of collection practices that destroy reef habitats. Management and enforcement of collection activities in major source countries such as Indonesia and the Philippines remain weak. Strengthening US trade laws and enforcement capabilities combined with increasing consumer and industry demand for responsible conservation can create strong incentives for improving management in source countries. This is particularly important in light of the March 2010 failure of the parties to the Convention on International Trade in Endangered Species (CITES) to take action on key groups of corals

    Genome sequencing and transcriptome analyses of the Siberian hamster hypothalamus identify mechanisms for seasonal energy balance

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    We thank the manuscript reviewers for constructive feedback; David G. Hazlerigg, Cristina Saenz de Miera, and Valerie Simonneaux for genome sequence contributions; Nicolas Scrutton and Lindsey Duguid for expert technical assistance; and Michael Jarsulic for technical assistance on the high-performance computing clusters. This project was supported by a project research grant from The British Society for Neuroendocrinology (to T.J.S.); Grants BB/M021629/1 and BB/M001555/1 (to F.J.P.E.) from the Biotechnology and Biological Sciences Research Council, and Grants UL1-TR000430 (to T.J.S. and B.J.P.) and R01-AI067406 (to B.J.P.) from the National Institutes of Health. T.J.S. is funded by The Leverhulme Trust. The Center for Research Informatics was supported by the Biological Sciences Division at the University of Chicago with additional support provided by the Institute for Translational Medicine/Clinical and Translational award (NIH 5UL1TR002389-02) and the University of Chicago Comprehensive Cancer Center Support Grant (NIH Grant P30CA014599). The bioinformatics analysis was performed on high-performance computing clusters at the Center for Research Informatics, Biological Sciences Division. P.B. was funded by the Scottish Government Rural and Environment Science and Analytical Services Division grant to the Rowett Institute.Peer reviewedPublisher PD

    Constitutive mutants of the protein kinase STE11 activate the yeast pheromone response pathway in the absence of the G protein.

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    STE4 encodes the beta-subunit of a heterotrimeric guanine nucleotide-binding protein (G protein) that is an early and essential component of the pheromone signal transduction pathway. From a ste4 deletion strain we have isolated both dominant and recessive suppressors that show increased transcription of pheromone responsive genes and have regained the ability to mate, albeit at a low level. Each of these suppressor mutations suppresses ste4 and ste5 deletions but not deletions in STE7, STE11, or STE12. Among the dominant mutations, we have identified two alleles of STE11, a gene that encodes a protein kinase activity essential for mating. One allele contains an alteration in the putative regulatory domain of the protein kinase; the second allele has an alteration in the catalytic site. In strains carrying these mutations, a second protein kinase required for mating, STE7, becomes hyperphosphorylated, just as it does in wild-type cells treated with pheromone. Thus, a protein kinase cascade appears to be an essential feature of the response pathway and probably connects the receptor/G protein to an identified transcription factor, STE12
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