1,338 research outputs found

    New bryophyte taxon records for tropical countries 4

    Get PDF
    Nord Kivu: c. 6 km north of Lubero, on sandy soil of tree-shaded road cutting, c. 1800m, 0º 8' S, 29º 14' E, 11 Aug 1988. C.R. Stevenson Z 78f, det. E.W. Jones (BM, & herb. C.R. Stevenson). Growing mixed with Frullania serrata, Pilotrichella, Trachypodopsis, etc. Distrib.: Annobon, Bioko, Burundi, Cameroun, Kenya, Rwanda, Sao Tome, Tanzania

    New bryophyte taxon records for tropical countries 1

    Get PDF
    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

    Primary and secondary eclipse spectroscopy with JWST: exploring the exoplanet parameter space

    Get PDF
    Eclipse exoplanet spectroscopy has yielded detection of H_2O, CH_4, CO_2 and CO in the atmosphere of hot jupiters and neptunes. About 40 large terrestrial planets are announced or confirmed, two of which are transiting, and another deemed habitable. Hence the potential for eclipse spectroscopy of terrestrial planets with James Webb Space Telescope (JWST) has become an active field of study. We explore the parameter space (type of stars, planet orbital periods and types, and instruments/wavelengths) in terms of the signal-to-noise ratio (S/N) achievable on the detection of spectroscopic features. We use analytic formula and model data for both the astrophysical scene and the instrument, to plot S/N contour maps, while indicating how the S/N scales with the fixed parameters. We systematically compare stellar photon noise-only figures with ones including detailed instrumental and zodiacal noises. Likelihood of occurring targets is based both on model and catalog star population of the solar neighborhood. The 9.6 micron ozone band is detectable (S/N = 3) with JWST, for a warm super-earth 6.7 pc away, using ~2% of the 5-year nominal mission time (summing observations, M4V and lighter host star for primary eclipses, M5V for secondary). If every star up to this mass limit and distance were to host a habitable planet, there should be statistically ~1 eclipsing case. Investigation of systematic noises in the co-addition of 5 years worth-, tens of days separated-, hours-long observations is critical, complemented by dedicated characterisation of the instruments, currently in integration phase. The census of nearby transiting habitable planets must be complete before the beginning of science operations.Comment: Accepted for publication in A&A, 16 pages, 19 figure

    Coinfection and Emergence of Rifamycin Resistance during a Recurrent Clostridium difficile Infection

    Get PDF
    Clostridium difficile (Peptoclostridium difficile) is a common health care-associated infection with a disproportionately high incidence in elderly patients. Disease symptoms range from mild diarrhea to life-threatening pseudomembranous colitis. Around 20% of patients may suffer recurrent disease, which often requires rehospitalization of patients. C. difficile was isolated from stool samples from a patient with two recurrent C. difficile infections. PCR ribotyping, whole-genome sequencing, and phenotypic assays were used to characterize these isolates. Genotypic and phenotypic screening of C. difficile isolates revealed multiple PCR ribotypes present and the emergence of rifamycin resistance during the infection cycle. Understanding both the clinical and bacterial factors that contribute to the course of recurrent infection could inform strategies to reduce recurrence. (This study has been registered at ClinicalTrials.gov under registration no. NCT01670149.

    'A bite before bed': exposure to malaria vectors outside the times of net use in the highlands of western Kenya.

    Get PDF
    BACKGROUND: The human population in the highlands of Nyanza Province, western Kenya, is subject to sporadic epidemics of Plasmodium falciparum. Indoor residual spraying (IRS) and long-lasting insecticide treated nets (LLINs) are used widely in this area. These interventions are most effective when Anopheles rest and feed indoors and when biting occurs at times when individuals use LLINs. It is therefore important to test the current assumption of vector feeding preferences, and late night feeding times, in order to estimate the extent to which LLINs protect the inhabitants from vector bites. METHODS: Mosquito collections were made for six consecutive nights each month between June 2011 and May 2012. CDC light-traps were set next to occupied LLINs inside and outside randomly selected houses and emptied hourly. The net usage of residents, their hours of house entry and exit and times of sleeping were recorded and the individual hourly exposure to vectors indoors and outdoors was calculated. Using these data, the true protective efficacy of nets (P*), for this population was estimated, and compared between genders, age groups and from month to month. RESULTS: Primary vector species (Anopheles funestus s.l. and Anopheles arabiensis) were more likely to feed indoors but the secondary vector Anopheles coustani demonstrated exophagic behaviour (p < 0.05). A rise in vector biting activity was recorded at 19:30 outdoors and 18:30 indoors. Individuals using LLINs experienced a moderate reduction in their overall exposure to malaria vectors from 1.3 to 0.47 bites per night. The P* for the population over the study period was calculated as 51% and varied significantly with age and season (p < 0.01). CONCLUSIONS: In the present study, LLINs offered the local population partial protection against malaria vector bites. It is likely that P* would be estimated to be greater if the overall suppression of the local vector population due to widespread community net use could be taken into account. However, the overlap of early biting habit of vectors and human activity in this region indicates that additional methods of vector control are required to limit transmission. Regular surveillance of both vector behaviour and domestic human-behaviour patterns would assist the planning of future control interventions in this region

    Molecular Characterization Reveals Diverse and Unknown Malaria Vectors in the Western Kenyan Highlands.

    Get PDF
    The success of mosquito-based malaria control is dependent upon susceptible bionomic traits in local malaria vectors. It is crucial to have accurate and reliable methods to determine mosquito species composition in areas subject to malaria. An unexpectedly diverse set of Anopheles species was collected in the western Kenyan highlands, including unidentified and potentially new species carrying the malaria parasite Plasmodium falciparum. This study identified 2,340 anopheline specimens using both ribosomal DNA internal transcribed spacer region 2 and mitochondrial DNA cytochrome oxidase subunit 1 loci. Seventeen distinct sequence groups were identified. Of these, only eight could be molecularly identified through comparison to published and voucher sequences. Of the unidentified species, four were found to carry P. falciparum by circumsporozoite enzyme-linked immunosorbent assay and polymerase chain reaction, the most abundant of which had infection rates comparable to a primary vector in the area, Anopheles funestus. High-quality adult specimens of these unidentified species could not be matched to museum voucher specimens or conclusively identified using multiple keys, suggesting that they may have not been previously described. These unidentified vectors were captured outdoors. Diverse and unknown species have been incriminated in malaria transmission in the western Kenya highlands using molecular identification of unusual morphological variants of field specimens. This study demonstrates the value of using molecular methods to compliment vector identifications and highlights the need for accurate characterization of mosquito species and their associated behaviors for effective malaria control

    Risk factors for Plasmodium falciparum infection in the Kenyan Highlands: a cohort study.

    Get PDF
    BACKGROUND: Malaria transmission in African highland areas can be prone to epidemics, with minor fluctuations in temperature or altitude resulting in highly heterogeneous transmission. In the Kenyan Highlands, where malaria prevalence has been increasing, characterising malaria incidence and identifying risk factors for infection is complicated by asymptomatic infection. METHODS: This all-age cohort study, one element of the Malaria Transmission Consortium, involved monthly follow-up of 3155 residents of the Kisii and Rachuonyo South districts during June 2009-June 2010. Participants were tested for malaria using rapid diagnostic testing at every visit, regardless of symptoms. RESULTS: The incidence of Plasmodium falciparum infection was 0.2 cases per person, although infections were clustered within individuals and over time, with the majority of infections detected in the last month of the cohort study. Overall, incidence was higher in the Rachuonyo district and infections were detected most frequently in 5-10-year-olds. The majority of infections were asymptomatic (58%). Travel away from the study area was a notable risk factor for infection. CONCLUSIONS: Identifying risk factors for malaria infection can help to guide targeting of interventions to populations most likely to be exposed to malaria

    Effector Memory Th1 CD4 T Cells Are Maintained in a Mouse Model of Chronic Malaria

    Get PDF
    Protection against malaria often decays in the absence of infection, suggesting that protective immunological memory depends on stimulation. Here we have used CD4+ T cells from a transgenic mouse carrying a T cell receptor specific for a malaria protein, Merozoite Surface Protein-1, to investigate memory in a Plasmodium chabaudi infection. CD4+ memory T cells (CD44hiIL-7Rα+) developed during the chronic infection, and were readily distinguishable from effector (CD62LloIL-7Rα−) cells in acute infection. On the basis of cell surface phenotype, we classified memory CD4+ T cells into three subsets: central memory, and early and late effector memory cells, and found that early effector memory cells (CD62LloCD27+) dominated the chronic infection. We demonstrate a linear pathway of differentiation from central memory to early and then late effector memory cells. In adoptive transfer, CD44hi memory cells from chronically infected mice were more effective at delaying and reducing parasitemia and pathology than memory cells from drug-treated mice without chronic infection, and contained a greater proportion of effector cells producing IFN-γ and TNFα, which may have contributed to the enhanced protection. These findings may explain the observation that in humans with chronic malaria, activated effector memory cells are best maintained in conditions of repeated exposure

    Shifting markers of identity in East London's diasporic religious spaces

    Get PDF
    This article discusses the historical and geographical contexts of diasporic religious buildings in East London, revealing – contrary both to conventional narratives of immigrant integration, mobility, and succession and to identitarian understandings of belonging – that in such spaces and in the concrete devotional practices enacted in them, markers and boundaries of identity (ritual, spatial, and political) are contested, renegotiated, erased, and rewritten. It draws on a series of case-studies: Fieldgate Street Synagogue in its interrelationship with the East London Mosque; St Antony's Catholic Church in Forest Gate where Hindus and Christians worship together; and the intertwined histories of Methodism and Anglicanism in Bow Road. Exploration of the intersections between ethnicity, religiosity, and class illuminates the ambiguity and instability of identity-formation and expression within East London's diasporic faith spaces
    • …
    corecore