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Sample records for african trypanosome traversal

  1. Protease activated receptor signaling is required for African trypanosome traversal of human brain microvascular endothelial cells.

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    Dennis J Grab

    Full Text Available BACKGROUND: Using human brain microvascular endothelial cells (HBMECs as an in vitro model for how African trypanosomes cross the human blood-brain barrier (BBB we recently reported that the parasites cross the BBB by generating calcium activation signals in HBMECs through the activity of parasite cysteine proteases, particularly cathepsin L (brucipain. In the current study, we examined the possible role of a class of protease stimulated HBMEC G protein coupled receptors (GPCRs known as protease activated receptors (PARs that might be implicated in calcium signaling by African trypanosomes. METHODOLOGY/PRINCIPAL FINDINGS: Using RNA interference (RNAi we found that in vitro PAR-2 gene (F2RL1 expression in HBMEC monolayers could be reduced by over 95%. We also found that the ability of Trypanosoma brucei rhodesiense to cross F2RL1-silenced HBMEC monolayers was reduced (39%-49% and that HBMECs silenced for F2RL1 maintained control levels of barrier function in the presence of the parasite. Consistent with the role of PAR-2, we found that HBMEC barrier function was also maintained after blockade of Galpha(q with Pasteurella multocida toxin (PMT. PAR-2 signaling has been shown in other systems to have neuroinflammatory and neuroprotective roles and our data implicate a role for proteases (i.e. brucipain and PAR-2 in African trypanosome/HBMEC interactions. Using gene-profiling methods to interrogate candidate HBMEC pathways specifically triggered by brucipain, several pathways that potentially link some pathophysiologic processes associated with CNS HAT were identified. CONCLUSIONS/SIGNIFICANCE: Together, the data support a role, in part, for GPCRs as molecular targets for parasite proteases that lead to the activation of Galpha(q-mediated calcium signaling. The consequence of these events is predicted to be increased permeability of the BBB to parasite transmigration and the initiation of neuroinflammation, events precursory to CNS disease.

  2. Environmental sensing by African trypanosomes.

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    Roditi, Isabel; Schumann, Gabriela; Naguleswaran, Arunasalam

    2016-08-01

    African trypanosomes, which divide their life cycle between mammals and tsetse flies, are confronted with environments that differ widely in temperature, nutrient availability and host responses to infection. In particular, since trypanosomes cannot predict when they will be transmitted between hosts, it is vital for them to be able to sense and adapt to their milieu. Thanks to technical advances, significant progress has been made in understanding how the parasites perceive external stimuli and react to them. There is also a growing awareness that trypanosomes use a variety of mechanisms to exchange information with each other, thereby enhancing their chances of survival. PMID:27131101

  3. Toxicity of myristic acid analogs toward African trypanosomes.

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    Doering, T L; Lu, T.; Werbovetz, K A; Gokel, G W; Hart, G W; Gordon, J I; Englund, P T

    1994-01-01

    New drugs are needed for treatment of diseases caused by African trypanosomes. One possible target for chemotherapy is the biosynthesis of the glycosyl phosphatidyl-inositol (GPI) of this parasite's variant surface glycoprotein (VSG). Unlike mammalian GPIs, the diacylglycerol moiety of the VSG anchor contains only myristate (tetradecanoate), added in unique remodeling reactions. We previously found that 11-oxatetradecanoic acid [i.e., 10-(propoxy)decanoic acid] is selectively toxic to trypano...

  4. Haptoglobin-hemoglobin receptor independent killing of African trypanosomes by human serum and trypanosome lytic factors.

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    Bullard, Whitney; Kieft, Rudo; Capewell, Paul; Veitch, Nicola J; Macleod, Annette; Hajduk, Stephen L

    2012-01-01

    The haptoglobin-hemoglobin receptor (HpHbR) of African trypanosomes plays a critical role in human innate immunity against these parasites. Localized to the flagellar pocket of the veterinary pathogen Trypanosoma brucei brucei this receptor binds Trypanosome Lytic Factor-1 (TLF-1), a subclass of human high-density lipoprotein (HDL) facilitating endocytosis, lysosomal trafficking and subsequent killing. Recently, we found that group 1 Trypanosoma brucei gambiense does not express a functional HpHbR. We now show that loss of the TbbHpHbR reduces the susceptibility of T. b. brucei to human serum and TLF-1 by 100- and 10,000-fold, respectively. The relatively high concentrations of human serum and TLF-1 needed to kill trypanosomes lacking the HpHbR indicates that high affinity TbbHpHbR binding enhances the cytotoxicity; however, in the absence of TbbHpHbR, other receptors or fluid phase endocytosis are sufficient to provide some level of susceptibility. Human serum contains a second innate immune factor, TLF-2, that has been suggested to kill trypanosomes independently of the TbbHpHbR. We found that T. b. brucei killing by TLF-2 was reduced in TbbHpHbR-deficient cells but to a lesser extent than TLF-1. This suggests that both TLF-1 and TLF-2 can be taken up via the TbbHpHbR but that alternative pathways exist for the uptake of these toxins. Together the findings reported here extend our previously published studies and suggest that group 1 T. b. gambiense has evolved multiple mechanisms to avoid killing by trypanolytic human serum factors. PMID:22286709

  5. The killing of African trypanosomes by ethidium bromide.

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    Arnab Roy Chowdhury

    Full Text Available Introduced in the 1950s, ethidium bromide (EB is still used as an anti-trypanosomal drug for African cattle although its mechanism of killing has been unclear and controversial. EB has long been known to cause loss of the mitochondrial genome, named kinetoplast DNA (kDNA, a giant network of interlocked minicircles and maxicircles. However, the existence of viable parasites lacking kDNA (dyskinetoplastic led many to think that kDNA loss could not be the mechanism of killing. When recent studies indicated that kDNA is indeed essential in bloodstream trypanosomes and that dyskinetoplastic cells survive only if they have a compensating mutation in the nuclear genome, we investigated the effect of EB on kDNA and its replication. We here report some remarkable effects of EB. Using EM and other techniques, we found that binding of EB to network minicircles is low, probably because of their association with proteins that prevent helix unwinding. In contrast, covalently-closed minicircles that had been released from the network for replication bind EB extensively, causing them, after isolation, to become highly supertwisted and to develop regions of left-handed Z-DNA (without EB, these circles are fully relaxed. In vivo, EB causes helix distortion of free minicircles, preventing replication initiation and resulting in kDNA loss and cell death. Unexpectedly, EB also kills dyskinetoplastic trypanosomes, lacking kDNA, by inhibiting nuclear replication. Since the effect on kDNA occurs at a >10-fold lower EB concentration than that on nuclear DNA, we conclude that minicircle replication initiation is likely EB's most vulnerable target, but the effect on nuclear replication may also contribute to cell killing.

  6. Escape mechanisms of African trypanosomes: why trypanosomosis is keeping us awake.

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    Cnops, Jennifer; Magez, Stefan; De Trez, Carl

    2015-03-01

    African trypanosomes have been around for more than 100 million years, and have adapted to survival in a very wide host range. While various indigenous African mammalian host species display a tolerant phenotype towards this parasitic infection, and hence serve as perpetual reservoirs, many commercially important livestock species are highly disease susceptible. When considering humans, they too display a highly sensitive disease progression phenotype for infections with Trypanosoma brucei rhodesiense or Trypanosoma brucei gambiense, while being intrinsically resistant to infections with other trypanosome species. As extracellular trypanosomes proliferate and live freely in the bloodstream and lymphatics, they are constantly exposed to the immune system. Due to co-evolution, this environment however no longer poses a hostile threat, but has become the niche environment where trypanosomes thrive and obligatory await transmission through the bites of tsetse flies or other haematophagic vectors, ideally without causing severe side infection-associated pathology to their host. Hence, African trypanosomes have acquired various mechanisms to manipulate and control the host immune response, evading effective elimination. Despite the extensive research into trypanosomosis over the past 40 years, many aspects of the anti-parasite immune response remain to be solved and no vaccine is currently available. Here we review the recent work on the different escape mechanisms employed by African Trypanosomes to ensure infection chronicity and transmission potential. PMID:25479093

  7. Regulation of surface coat exchange by differentiating African trypanosomes.

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    Gruszynski, Amy E; van Deursen, Frederick J; Albareda, Maria C; Best, Alexander; Chaudhary, Kshitiz; Cliffe, Laura J; del Rio, Laura; Dunn, Joe Dan; Ellis, Louise; Evans, Krystal J; Figueiredo, Juliana M; Malmquist, Nicholas A; Omosun, Yusuf; Palenchar, Jennifer B; Prickett, Sara; Punkosdy, George A; van Dooren, Giel; Wang, Qian; Menon, Anant K; Matthews, Keith R; Bangs, James D

    2006-06-01

    African trypanosomes (Trypanosoma brucei) have a digenetic lifecycle that alternates between the mammalian bloodstream and the tsetse fly vector. In the bloodstream, replicating long slender parasites transform into non-dividing short stumpy forms. Upon transmission into the fly midgut, short stumpy cells differentiate into actively dividing procyclics. A hallmark of this process is the replacement of the bloodstream-stage surface coat composed of variant surface glycoprotein (VSG) with a new coat composed of procyclin. Pre-existing VSG is shed by a zinc metalloprotease activity (MSP-B) and glycosylphosphatidylinositol-specific phospholipase C (GPI-PLC). We now provide a detailed analysis of the coordinate and inverse regulation of these activities during synchronous differentiation. MSP-B mRNA and protein levels are upregulated during differentiation at the same time as proteolysis whereas GPI-PLC levels decrease. When transcription or translation is inhibited, VSG release is incomplete and a substantial amount of protein stays cell-associated. Both modes of release are still evident under these conditions, but GPI hydrolysis plays a quantitatively minor role during normal differentiation. Nevertheless, GPI biosynthesis shifts early in differentiation from a GPI-PLC sensitive structure to a resistant procyclic-type anchor. Translation inhibition also results in a marked increase in the mRNA levels of both MSP-B and GPI-PLC, consistent with negative regulation by labile protein factors. The relegation of short stumpy surface GPI-PLC to a secondary role in differentiation suggests that it may play a more important role as a virulence factor within the mammalian host. PMID:16564583

  8. Evolution of the serum resistance-associated SRA gene in African trypanosomes

    Czech Academy of Sciences Publication Activity Database

    Lai, D. H.; Wang, Q.P.; Lukeš, Julius; Lun, Z.R.

    2009-01-01

    Roč. 54, č. 7 (2009), s. 1275-1278. ISSN 1001-6538 R&D Projects: GA MŠk 2B06129 Institutional research plan: CEZ:AV0Z60220518 Keywords : SRA * SRAbc * evolution * African trypanosomes Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 0.898, year: 2009

  9. Natural products active against African trypanosomes: a step towards new drugs

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    Hoet, Sara; Opperdoes, Frederik; Brun, Reto; Quetin-Leclercq, Joëlle

    2004-01-01

    This review covers compounds with activity on African trypanosomes (mainly Trypanosoma brucei subsp.,T congolense and T vivax) isolated from natural sources and is organized according to the structure of the etabolites (alkaloids, phenolic derivatives, quinones, terpenes and other metabolites). The literature from he mid-1980s up to June 2003 is reviewed and 89 references are cited.

  10. Glycolysis in the African Trypanosome: Targeting Enzymes and Their Subcellular Compartments for Therapeutic Development

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    James C. Morris; Morris, Meredith T.; Dodson, Heidi C.; Coley, April F.

    2011-01-01

    Subspecies of the African trypanosome, Trypanosoma brucei, which cause human African trypanosomiasis, are transmitted by the tsetse fly, with transmission-essential lifecycle stages occurring in both the insect vector and human host. During infection of the human host, the parasite is limited to using glycolysis of host sugar for ATP production. This dependence on glucose breakdown presents a series of targets for potential therapeutic development, many of which have been explored and validat...

  11. Trypanin, a component of the flagellar Dynein regulatory complex, is essential in bloodstream form African trypanosomes.

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    Katherine S Ralston

    2006-09-01

    Full Text Available The Trypanosoma brucei flagellum is a multifunctional organelle with critical roles in motility, cellular morphogenesis, and cell division. Although motility is thought to be important throughout the trypanosome lifecycle, most studies of flagellum structure and function have been restricted to the procyclic lifecycle stage, and our knowledge of the bloodstream form flagellum is limited. We have previously shown that trypanin functions as part of a flagellar dynein regulatory system that transmits regulatory signals from the central pair apparatus and radial spokes to axonemal dyneins. Here we investigate the requirement for this dynein regulatory system in bloodstream form trypanosomes. We demonstrate that trypanin is localized to the flagellum of bloodstream form trypanosomes, in a pattern identical to that seen in procyclic cells. Surprisingly, trypanin RNA interference is lethal in the bloodstream form. These knockdown mutants fail to initiate cytokinesis, but undergo multiple rounds of organelle replication, accumulating multiple flagella, nuclei, kinetoplasts, mitochondria, and flagellum attachment zone structures. These findings suggest that normal flagellar beat is essential in bloodstream form trypanosomes and underscore the emerging concept that there is a dichotomy between trypanosome lifecycle stages with respect to factors that contribute to cell division and cell morphogenesis. This is the first time that a defined dynein regulatory complex has been shown to be essential in any organism and implicates the dynein regulatory complex and other enzymatic regulators of flagellar motility as candidate drug targets for the treatment of African sleeping sickness.

  12. Bromodomain Proteins Contribute to Maintenance of Bloodstream Form Stage Identity in the African Trypanosome.

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    Schulz, Danae; Mugnier, Monica R; Paulsen, Eda-Margaret; Kim, Hee-Sook; Chung, Chun-wa W; Tough, David F; Rioja, Inmaculada; Prinjha, Rab K; Papavasiliou, F Nina; Debler, Erik W

    2015-12-01

    Trypanosoma brucei, the causative agent of African sleeping sickness, is transmitted to its mammalian host by the tsetse. In the fly, the parasite's surface is covered with invariant procyclin, while in the mammal it resides extracellularly in its bloodstream form (BF) and is densely covered with highly immunogenic Variant Surface Glycoprotein (VSG). In the BF, the parasite varies this highly immunogenic surface VSG using a repertoire of ~2500 distinct VSG genes. Recent reports in mammalian systems point to a role for histone acetyl-lysine recognizing bromodomain proteins in the maintenance of stem cell fate, leading us to hypothesize that bromodomain proteins may maintain the BF cell fate in trypanosomes. Using small-molecule inhibitors and genetic mutants for individual bromodomain proteins, we performed RNA-seq experiments that revealed changes in the transcriptome similar to those seen in cells differentiating from the BF to the insect stage. This was recapitulated at the protein level by the appearance of insect-stage proteins on the cell surface. Furthermore, bromodomain inhibition disrupts two major BF-specific immune evasion mechanisms that trypanosomes harness to evade mammalian host antibody responses. First, monoallelic expression of the antigenically varied VSG is disrupted. Second, rapid internalization of antibodies bound to VSG on the surface of the trypanosome is blocked. Thus, our studies reveal a role for trypanosome bromodomain proteins in maintaining bloodstream stage identity and immune evasion. Importantly, bromodomain inhibition leads to a decrease in virulence in a mouse model of infection, establishing these proteins as potential therapeutic drug targets for trypanosomiasis. Our 1.25Å resolution crystal structure of a trypanosome bromodomain in complex with I-BET151 reveals a novel binding mode of the inhibitor, which serves as a promising starting point for rational drug design. PMID:26646171

  13. Identification of trans-sialidases as a common mediator of endothelial cell activation by African trypanosomes.

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    Zeinab Ammar

    Full Text Available Understanding African Trypanosomiasis (AT host-pathogen interaction is the key to an "anti-disease vaccine", a novel strategy to control AT. Here we provide a better insight into this poorly described interaction by characterizing the activation of a panel of endothelial cells by bloodstream forms of four African trypanosome species, known to interact with host endothelium. T. congolense, T. vivax, and T. b. gambiense activated the endothelial NF-κB pathway, but interestingly, not T. b. brucei. The parasitic TS (trans-sialidases mediated this NF-κB activation, remarkably via their lectin-like domain and induced production of pro-inflammatory molecules not only in vitro but also in vivo, suggesting a considerable impact on pathogenesis. For the first time, TS activity was identified in T. b. gambiense BSF which distinguishes it from the subspecies T. b. brucei. The corresponding TS were characterized and shown to activate endothelial cells, suggesting that TS represent a common mediator of endothelium activation among trypanosome species with divergent physiopathologies.

  14. Constraints to estimating the prevalence of trypanosome infections in East African zebu cattle

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    Cox Andrew P

    2010-09-01

    Full Text Available Abstract Background In East Africa, animal trypanosomiasis is caused by many tsetse transmitted protozoan parasites including Trypanosoma vivax, T. congolense and subspecies of T. brucei s.l. (T. b. brucei and zoonotic human infective T. b. rhodesiense that may co-circulate in domestic and wild animals. Accurate species-specific prevalence measurements of these parasites in animal populations are complicated by mixed infections of trypanosomes within individual hosts, low parasite densities and difficulties in conducting field studies. Many Polymerase Chain Reaction (PCR based diagnostic tools are available to characterise and quantify infection in animals. These are important for assessing the contribution of infections in animal reservoirs and the risk posed to humans from zoonotic trypanosome species. New matrices for DNA capture have simplified large scale field PCR analyses but few studies have examined the impact of these techniques on prevalence estimations. Results The Whatman FTA matrix has been evaluated using a random sample of 35 village zebu cattle from a population naturally exposed to trypanosome infection. Using a generic trypanosome-specific PCR, prevalence was systematically evaluated. Multiple PCR samples taken from single FTA cards demonstrated that a single punch from an FTA card is not sufficient to confirm the infectivity status of an individual animal as parasite DNA is unevenly distributed across the card. At low parasite densities in the host, this stochastic sampling effect results in underestimation of prevalence based on single punch PCR testing. Repeated testing increased the estimated prevalence of all Trypanosoma spp. from 9.7% to 86%. Using repeat testing, a very high prevalence of pathogenic trypanosomes was detected in these local village cattle: T. brucei (34.3%, T. congolense (42.9% and T. vivax (22.9%. Conclusions These results show that, despite the convenience of Whatman FTA cards and specific PCR based

  15. Cytosolic peroxidases protect the lysosome of bloodstream African trypanosomes from iron-mediated membrane damage.

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    Corinna Hiller

    2014-04-01

    Full Text Available African trypanosomes express three virtually identical non-selenium glutathione peroxidase (Px-type enzymes which preferably detoxify lipid-derived hydroperoxides. As shown previously, bloodstream Trypanosoma brucei lacking the mitochondrial Px III display only a weak and transient proliferation defect whereas parasites that lack the cytosolic Px I and Px II undergo extremely fast lipid peroxidation and cell lysis. The phenotype can completely be rescued by supplementing the medium with the α-tocopherol derivative Trolox. The mechanism underlying the rapid cell death remained however elusive. Here we show that the lysosome is the origin of the cellular injury. Feeding the px I-II knockout parasites with Alexa Fluor-conjugated dextran or LysoTracker in the presence of Trolox yielded a discrete lysosomal staining. Yet upon withdrawal of the antioxidant, the signal became progressively spread over the whole cell body and was completely lost, respectively. T. brucei acquire iron by endocytosis of host transferrin. Supplementing the medium with iron or transferrin induced, whereas the iron chelator deferoxamine and apo-transferrin attenuated lysis of the px I-II knockout cells. Immunofluorescence microscopy with MitoTracker and antibodies against the lysosomal marker protein p67 revealed that disintegration of the lysosome precedes mitochondrial damage. In vivo experiments confirmed the negligible role of the mitochondrial peroxidase: Mice infected with px III knockout cells displayed only a slightly delayed disease development compared to wild-type parasites. Our data demonstrate that in bloodstream African trypanosomes, the lysosome, not the mitochondrion, is the primary site of oxidative damage and cytosolic trypanothione/tryparedoxin-dependent peroxidases protect the lysosome from iron-induced membrane peroxidation. This process appears to be closely linked to the high endocytic rate and distinct iron acquisition mechanisms of the infective

  16. Analysis of host genetic factors influencing African trypanosome species infection in a cohort of Tanzanian Bos indicus cattle.

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    Karimuribo, Esron D; Morrison, Liam J; Black, Alana; Turner, C Michael R; Kambarage, Dominic M; Ballingall, Keith T

    2011-06-30

    Trypanosomosis caused by infection with protozoan parasites of the genus Trypanosoma is a major health constraint to cattle production in many African countries. One hundred and seventy one Bos indicus cattle from traditional pastoral Maasai (87) and more intensively managed Boran (84) animals in Tanzania were screened by PCR for the presence of African animal trypanosomes (Trypanosoma congolense, Trypanosoma vivax and Trypanosoma brucei), using blood samples archived on FTA cards. All cattle screened for trypanosomes were also genotyped at the highly polymorphic major histocompatibility complex (MHC) class II DRB3 locus to investigate possible associations between host MHC and trypanosome infection. Overall, 23.4% of the 171 cattle tested positive for at least one of the three trypanosome species. The prevalence of individual trypanosome species was 8.8% (T. congolense), 4.7% (T. vivax) and 15.8% (T. brucei). The high prevalence of T. brucei compared with T. congolense and T. vivax was unexpected as this species has previously been considered to be of lesser importance in terms of African bovine trypanosomosis. Significantly higher numbers of Maasai cattle were infected with T. brucei (23.0%, p=0.009) and T. congolense (13.8%, p=0.019) compared with Boran cattle (8.3% and 3.6%, respectively). Analysis of BoLA-DRB3 diversity in this cohort identified extensive allelic diversity. Thirty-three BoLA-DRB3 PCR-RFLP defined alleles were identified. One allele (DRB3*15) was significantly associated with an increased risk (odds ratio, OR=2.71, p=0.034) of T. brucei infection and three alleles (DRB3*35, *16 and *23) were associated with increased risk of T. congolense infection. While further work is required to dissect the role of these alleles in susceptibility to T. brucei and T. congolense infections, this study demonstrates the utility of FTA archived blood samples in combined molecular analyses of both host and pathogen. PMID:21377802

  17. Deforestation does not affect the prevalence of a common trypanosome in African birds.

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    Valkiūnas, Gediminas; Iezhova, Tatjana A; Sehgal, Ravinder N M

    2016-10-01

    In spite of numerous reports of avian Trypanosoma spp. in birds throughout the world, patterns of the distribution and prevalence of these blood parasites remains insufficiently understood. It is clear that spatial heterogeneity influences parameters of parasite distributions in natural populations, but data regarding avian trypanosomes are scarce. Using microscopy and molecular diagnostic methods, we analysed the variation of prevalence of avian Trypanosoma parasites in two widespread African bird species, the yellow-whiskered greenbul Andropadus latirostris and the olive sunbird Cyanomitra olivacea. In all, 353 birds were captured in pristine forests and agroforest sites in Cameroon and Ghana. Overall, the prevalence of avian trypanosomes was 51.3%. Five morphospecies were reported (Trypanosoma everetti, T. anguiformis, T. avium, T. naviformis, T. ontarioensis). Trypanosoma everetti predominated, representing 98% of all Trypanosoma spp. reports, and it was present in both avian hosts. The prevalence of T. everetti was significantly less in the yellow-whiskered greenbul (19%) than olive sunbird (83%), and the same pattern of prevalence was reported in these avian hosts at different study sites. We found no interaction between sites and the prevalence of T. everetti. For both avian hosts, the prevalence did not differ significantly between pristine forests and agroforests. This indicates the same pattern of transmission at sites with different levels of deforestation and suggests that spatial heterogeneity related to deforestation does not affect the prevalence of avian Trypanosoma infections. It is likely that host-related factors, but not environmental conditions favour or reduce these parasite infections in forests of sub-Saharan Africa. Microscopic and PCR-based diagnostics showed the same sensitivity in diagnostics of T. everetti. We discuss the implications of these findings for the epidemiology of avian trypanosomiasis in natural populations. PMID:27421797

  18. JBP1 and JBP2 are two distinct thymidine hydroxylases involved in J biosynthesis in genomic DNA of African trypanosomes.

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    Cliffe, Laura J; Kieft, Rudo; Southern, Timothy; Birkeland, Shanda R; Marshall, Marion; Sweeney, Kate; Sabatini, Robert

    2009-04-01

    Genomic DNA of African trypanosomes contains a hypermodified thymidine residue termed base J (beta-d-glucosyl-HOMedU). This modified base is localized primarily to repetitive DNA, namely the telomeres, and is implicated in the regulation of antigenic variation. The base is synthesized in a two-step pathway. Initially, a thymidine residue in DNA is hydroxylated by a thymidine hydroxylase (TH). This intermediate (HOMedU) is then glucosylated to form base J. Two proteins involved in J synthesis, JBP1 (J binding protein 1) and JBP2, contain a putative TH domain related to the family of Fe(2+)/2-oxoglutarate-dependent hydroxylases. We have previously shown that mutations in the TH domain of JBP1 kill its ability to stimulate J synthesis. Here we show that mutation of key residues in the TH domain of JBP2 ablate its ability to induce de novo J synthesis. While the individual JBP1 null and JBP2 null trypanosomes have reduced J levels, the deletion of both JBP1 and JBP2 generates a cell line that completely lacks base J but still contains glucosyl-transferase activity. Reintroduction of JBP2 in the J-null trypanosome stimulates HOMedU formation and site-specific synthesis of base J. We conclude that JBP2 and JBP1 are the TH enzymes involved in J biosynthesis. PMID:19136460

  19. 25 years of African trypanosome research: From description to molecular dissection and new drug discovery ☆ ☆☆

    OpenAIRE

    Matthews, Keith R.

    2015-01-01

    Highlights • The Woods Hole ‘Molecular Parasitology Meeting’ celebrated its 25th meeting in 2014. • This ‘Perspective’ overviews discoveries in trypanosome biology since 1990. • New tools for gene function discovery have transformed trypanosome research. • Trypanosomes remain fascinating parasites with a unique biology. • This offers the potential to provide new therapeutic options.

  20. The phylogeography of trypanosomes from South American alligatorids and African crocodilids is consistent with the geological history of South American river basins and the transoceanic dispersal of Crocodylus at the Miocene

    OpenAIRE

    Fermino, Bruno R.; Viola, Laerte B; Paiva, Fernando; Garcia, Herakles A; de Paula, Catia D; Botero-Arias, Robinson; Takata, Carmen S. A.; Campaner, Marta; Hamilton, Patrick B; Camargo, Erney P.; Teixeira, Marta MG

    2013-01-01

    Background Little is known about the diversity, phylogenetic relationships, and biogeography of trypanosomes infecting non-mammalian hosts. In this study, we investigated the influence of host species and biogeography on shaping the genetic diversity, phylogenetic relationship, and distribution of trypanosomes from South American alligatorids and African crocodilids. Methods Small Subunit rRNA (SSU rRNA) and glycosomal Glyceraldehyde Phosphate Dehydrogenase (gGAPDH) genes were employed for ph...

  1. Trypanosome resistance to human innate immunity: targeting Achilles’ heel

    OpenAIRE

    Stephens, Natalie A.; Kieft, Rudo; MacLeod, Annette; Hajduk, Stephen L.

    2012-01-01

    Trypanosome lytic factors (TLFs) are powerful, naturally-occurring toxins in humans that provide sterile protection against infection by several African trypanosomes. These trypanocidal complexes predominantly enter the parasite by binding to the trypanosome haptoglobin/hemoglobin receptor (HpHbR), trafficking to the lysosome, causing membrane damage and ultimately, cell lysis. Despite TLF-mediated immunity, the parasites that cause human African Trypanosomiasis (HAT), Trypanosoma brucei rhod...

  2. Field and experimental evidence of a new caiman trypanosome species closely phylogenetically related to fish trypanosomes and transmitted by leeches

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    Fermino, Bruno R.; Fernando Paiva; Priscilla Soares; Luiz Eduardo R. Tavares; Viola, Laerte B; Ferreira, Robson C.; Robinson Botero-Arias; de-Paula, Cátia D.; Marta Campaner; Takata, Carmen S. A.; Teixeira, Marta M. G.; Camargo, Erney P.

    2015-01-01

    Trypanosoma terena and Trypanosoma ralphi are known species of the South American crocodilians Caiman crocodilus, Caiman yacare and Melanosuchus niger and are phylogenetically related to the tsetse-transmitted Trypanosoma grayi of the African Crocodylus niloticus. These trypanosomes form the Crocodilian clade of the terrestrial clade of the genus Trypanosoma. A PCR-survey for trypanosomes in caiman blood samples and in leeches taken from caimans revealed unknown trypanosome diversity and freq...

  3. Influence of Pastoralists' Sociocultural Activities on Tsetse-Trypanosome-Cattle Reservoir Interface: The Risk of Human African Trypanosomiasis in North-Central Nigeria.

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    Alhaji, N B; Kabir, J

    2016-06-01

    The study investigated socio-cultural characteristics of pastoralists that influenced on the tsetse-trypanosome-cattle reservoir interface thereby predisposing them to HAT in Niger State, North-central Nigeria. It was a cross-sectional survey of adult pastoral herders, aged 30 years and above, and conducted between October 2012 and February 2013. A face-to-face structured questionnaire was administered on the pastoralists nested in 96 cattle herds with questions focused on pastoralists' socio-cultural activities and behavioral practices related to HAT risk. Descriptive and analytic statistics were used to describe the obtained data. A total of 384 pastoralists participated, with mean age of 49.6  ± 10.76 SD years. Male respondents constituted 86.7% of gender, while pastoralists of age group 40-49 years constituted 35.4% of respondents. About 59.4% of the pastoralists had knowledge about HAT and its symptoms and only 33.9% of them believed that cattle served as reservoir of HAT trypanosome. Knowledge/belief levels of the pastoralists about African trypanosomiasis occurrence in humans and animals were statistically significant. Males were four times more likely to be exposed to HAT (OR = 3.67; 95% CI: 1.42, 9.52); age group 60-69 was also four times more likely to be exposed (OR = 3.59; 95% CI: 1.56, 8.28); and nomadic pastoralists were two times more likely to be exposed to HAT (OR = 2.07; 95% CI: 1.37, 3.14). All cultural practices significantly influenced exposure to HAT with extensive husbandry system three times more likely to predisposed pastoralists to HAT (OR = 3.21; 95% CI: 1.65, 6.24). Socio-cultural characteristics of pastoralists influenced exposure to HAT risk and, therefore, there is a need to sensitize them to bring changes to their socio-cultural practices and perceptions to achieve effective and long term sustainable HAT control. Elimination strategies of parasites in animals and vectors should be considered to avoid reintroduction

  4. Trypanosome resistance to human innate immunity: targeting Achilles' heel.

    Science.gov (United States)

    Stephens, Natalie A; Kieft, Rudo; Macleod, Annette; Hajduk, Stephen L

    2012-12-01

    Trypanosome lytic factors (TLFs) are powerful, naturally occurring toxins in humans that provide sterile protection against infection by several African trypanosomes. These trypanocidal complexes predominantly enter the parasite by binding to the trypanosome haptoglobin/hemoglobin receptor (HpHbR), trafficking to the lysosome, causing membrane damage and, ultimately, cell lysis. Despite TLF-mediated immunity, the parasites that cause human African Trypanosomiasis (HAT), Trypanosoma brucei rhodesiense and Trypanosoma brucei gambiense, have developed independent mechanisms of resistance to TLF killing. In this review we describe the parasite defenses that allow trypanosome infections of humans and discuss how targeting these apparent strengths of the parasite may reveal their Achilles' heel, leading to new approaches in the treatment of HAT. PMID:23059119

  5. Trypanosome resistance to human innate immunity: targeting Achilles’ heel

    Science.gov (United States)

    Stephens, Natalie A.; Kieft, Rudo; MacLeod, Annette; Hajduk, Stephen L.

    2015-01-01

    Trypanosome lytic factors (TLFs) are powerful, naturally-occurring toxins in humans that provide sterile protection against infection by several African trypanosomes. These trypanocidal complexes predominantly enter the parasite by binding to the trypanosome haptoglobin/hemoglobin receptor (HpHbR), trafficking to the lysosome, causing membrane damage and ultimately, cell lysis. Despite TLF-mediated immunity, the parasites that cause human African Trypanosomiasis (HAT), Trypanosoma brucei rhodesiense and Trypanosoma brucei gambiense, have developed independent mechanisms of resistance to TLF killing. Here we describe the parasite defenses that allow trypanosome infections of humans and discuss how targeting these apparent strengths of the parasite may reveal their Achilles’ heel, leading to new approaches in the treatment of HAT. PMID:23059119

  6. Field and experimental evidence of a new caiman trypanosome species closely phylogenetically related to fish trypanosomes and transmitted by leeches.

    Science.gov (United States)

    Fermino, Bruno R; Paiva, Fernando; Soares, Priscilla; Tavares, Luiz Eduardo R; Viola, Laerte B; Ferreira, Robson C; Botero-Arias, Robinson; de-Paula, Cátia D; Campaner, Marta; Takata, Carmen S A; Teixeira, Marta M G; Camargo, Erney P

    2015-12-01

    Trypanosoma terena and Trypanosoma ralphi are known species of the South American crocodilians Caiman crocodilus, Caiman yacare and Melanosuchus niger and are phylogenetically related to the tsetse-transmitted Trypanosoma grayi of the African Crocodylus niloticus. These trypanosomes form the Crocodilian clade of the terrestrial clade of the genus Trypanosoma. A PCR-survey for trypanosomes in caiman blood samples and in leeches taken from caimans revealed unknown trypanosome diversity and frequent mixed infections. Phylogenies based on SSU (small subunit) of rRNA and gGAPDH (glycosomal Glyceraldehyde Phosphate Dehydrogenase) gene sequences revealed a new trypanosome species clustering with T. terena and T. ralphi in the crocodilian clade and an additional new species nesting in the distant Aquatic clade of trypanosomes, which is herein named Trypanosoma clandestinus n. sp. This new species was found in Caiman yacare, Caiman crocodilus and M. niger from the Pantanal and Amazonian biomes in Brazil. Large numbers of dividing epimastigotes and unique thin and long trypomastigotes were found in the guts of leeches (Haementeria sp.) removed from the mouths of caimans. The trypanosomes recovered from the leeches had sequences identical to those of T. clandestinus of caiman blood samples. Experimental infestation of young caimans (Caiman yacare) with infected leeches resulted in long-lasting T. clandestinus infections that permitted us to delineate its life cycle. In contrast to T. terena, T. ralphi and T. grayi, which are detectable by hemoculturing, microscopy and standard PCR of caiman blood, T. clandestinus passes undetected by these methods due to very low parasitemia and could be detected solely by the more sensitive nested PCR method. T. clandestinus n. sp. is the first crocodilian trypanosome known to be transmitted by leeches and positioned in the aquatic clade closest to fish trypanosomes. Our data show that caimans can host trypanosomes of the aquatic or

  7. Field and experimental evidence of a new caiman trypanosome species closely phylogenetically related to fish trypanosomes and transmitted by leeches

    Directory of Open Access Journals (Sweden)

    Bruno R. Fermino

    2015-12-01

    Full Text Available Trypanosoma terena and Trypanosoma ralphi are known species of the South American crocodilians Caiman crocodilus, Caiman yacare and Melanosuchus niger and are phylogenetically related to the tsetse-transmitted Trypanosoma grayi of the African Crocodylus niloticus. These trypanosomes form the Crocodilian clade of the terrestrial clade of the genus Trypanosoma. A PCR-survey for trypanosomes in caiman blood samples and in leeches taken from caimans revealed unknown trypanosome diversity and frequent mixed infections. Phylogenies based on SSU (small subunit of rRNA and gGAPDH (glycosomal Glyceraldehyde Phosphate Dehydrogenase gene sequences revealed a new trypanosome species clustering with T. terena and T. ralphi in the crocodilian clade and an additional new species nesting in the distant Aquatic clade of trypanosomes, which is herein named Trypanosoma clandestinus n. sp. This new species was found in Caiman yacare, Caiman crocodilus and M. niger from the Pantanal and Amazonian biomes in Brazil. Large numbers of dividing epimastigotes and unique thin and long trypomastigotes were found in the guts of leeches (Haementeria sp. removed from the mouths of caimans. The trypanosomes recovered from the leeches had sequences identical to those of T. clandestinus of caiman blood samples. Experimental infestation of young caimans (Caiman yacare with infected leeches resulted in long-lasting T. clandestinus infections that permitted us to delineate its life cycle. In contrast to T. terena, T. ralphi and T. grayi, which are detectable by hemoculturing, microscopy and standard PCR of caiman blood, T. clandestinus passes undetected by these methods due to very low parasitemia and could be detected solely by the more sensitive nested PCR method. T. clandestinus n. sp. is the first crocodilian trypanosome known to be transmitted by leeches and positioned in the aquatic clade closest to fish trypanosomes. Our data show that caimans can host trypanosomes

  8. The use of specific and generic primers to identify trypanosome infections of wild tsetse flies in Tanzania by PCR.

    Science.gov (United States)

    Malele, Imna; Craske, Lisa; Knight, Claire; Ferris, Vanessa; Njiru, Zablon; Hamilton, Patrick; Lehane, Stella; Lehane, Mike; Gibson, Wendy

    2003-11-01

    The accurate identification of trypanosome species and subspecies remains a challenging task in the epidemiology of human and animal trypanosomiasis in tropical Africa. Currently, there are specific PCR tests to identify about 10 different species, subspecies or subgroups of African tsetse-transmitted trypanosomes. These PCR tests have been used here to identify trypanosomes in four species of tsetse (Glossina brevipalpis, G. pallidipes, G. swynnertoni, G. morsitans morsitans) from two areas of Tanzania. PCR using species-specific primers was performed on 1041 dissection-positive proboscides, giving an overall positive identification in 254 (24%). Of these, 61 proboscides (24%) contained two or more trypanosomes. The trypanosome with the greatest overall prevalence at both field sites was Trypanosoma simiae Tsavo, which was identified in a total of 118 infected tsetse proboscides (46%). At Pangani, T. godfreyi was found in G. pallidipes but not in G. brevipalpis, suggesting that these flies might have different susceptibility to this trypanosome or might have fed on a different range of hosts. A high proportion (about 75%) of trypanosome infections remained unidentified. To investigate the identity of these unidentified samples, we used primers complementary to the conserved regions of trypanosomal small subunit ribosomal RNA (ssu rRNA) genes to amplify variable segments of the gene. Amplified DNA fragments were cloned, sequenced and compared with ssu rRNA genes on database of known trypanosome species. In this way, we have tentatively identified two new trypanosomes: a trypanosome related to Trypanosoma vivax and a trypanosome related to T. godfreyi. The T. godfreyi-related trypanosome occurred frequently in the Tanzanian field samples and appears to be widespread. Molecular identification of these two new trypanosomes should now facilitate their isolation and full biological characterisation. PMID:14636688

  9. A tsetse and tabanid fly survey of African great apes habitats reveals the presence of a novel trypanosome lineage but the absence of Trypanosoma brucei

    Czech Academy of Sciences Publication Activity Database

    Votýpka, J.; Rádrová, J.; Skalický, T.; Jirků, M.; Jirsová, D.; Mihalca, A. D.; D'Amico, G.; Petrželková, Klára Judita; Modrý, D.; Lukeš, J.

    2015-01-01

    Roč. 45, č. 12 (2015), s. 741-748. ISSN 0020-7519 Institutional support: RVO:68081766 Keywords : Trypanosoma * Tsetse * Tabanids * African great apes * Gorillas * Transmission * Bloodmeal * Feeding preference Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 3.872, year: 2014

  10. A tsetse and tabanid fly survey of African great apes habitats reveals the presence of a novel trypanosome lineage but the absence of Trypanosoma brucei

    Czech Academy of Sciences Publication Activity Database

    Votýpka, Jan; Rádrová, Jana; Skalický, Tomáš; Jirků, Milan; Jirsová, D.; Mihalca, A. D.; D'Amico, G.; Petrželková, Klára Judita; Modrý, David; Lukeš, Julius

    2015-01-01

    Roč. 45, OCT 2015 (2015), s. 741-748. ISSN 0020-7519 R&D Projects: GA MŠk(CZ) EE2.3.30.0032 EU Projects: European Commission(XE) 316304 Grant ostatní: GA MŠk(CZ) EE2.3.20.0300 Institutional support: RVO:60077344 Keywords : Trypanosoma * Tsetse * Tabanids * African great apes * Gorillas * Transmission * Bloodmeal * Feeding preference Subject RIV: FN - Epidemiology, Contagious Diseases ; Clinical Immunology Impact factor: 3.872, year: 2014

  11. Trypanosomes of some Fennoscandian birds

    Directory of Open Access Journals (Sweden)

    Gordon F. Bennett

    1994-12-01

    Full Text Available Linear measurements and derived indices of trypanosomes from species of Fennoscandian birds were compared to those reported form Trypanosoma avium, T. everetti, T. ontarioensis and T. paddae. The trypanosomes encountered in the Fennoscandian birds were identified as T. avium from Tengmalm's owl Aegolius funereus and the pied flycatcher Ficedula hypoleuca, T. everetti from the great tit Parus major and collared flycatcher F. albicollis and T. ontarioensis from the collared flycatcher; T. paddae was not seen.

  12. Malaria and trypanosome transmission: different parasites, same rules?

    OpenAIRE

    Pollitt, Laura C.; MacGregor, Paula; Matthews, Keith; Reece, Sarah E.

    2011-01-01

    African trypanosomes produce different specialized stages for within-host replication and between-host transmission and therefore face a resource allocation trade-off between maintaining the current infection (survival) and investment into transmission (reproduction). Evolutionary theory predicts the resolution of this trade-off will significantly affect virulence and infectiousness. The application of life history theory to malaria parasites has provided novel insight into their strategies f...

  13. The Evolution of Trypanosomes Infecting Humans and Primates

    Directory of Open Access Journals (Sweden)

    Stevens Jamie

    1998-01-01

    Full Text Available Based on phylogenetic analysis of 18S rRNA sequences and clade taxon composition, this paper adopts a biogeographical approach to understanding the evolutionary relationships of the human and primate infective trypanosomes, Trypanosoma cruzi, T. brucei, T. rangeli and T. cyclops. Results indicate that these parasites have divergent origins and fundamentally different patterns of evolution. T. cruzi is placed in a clade with T. rangeli and trypanosomes specific to bats and a kangaroo. The predominantly South American and Australian origins of parasites within this clade suggest an ancient southern super-continent origin for ancestral T. cruzi, possibly in marsupials. T. brucei clusters exclusively with mammalian, salivarian trypanosomes of African origin, suggesting an evolutionary history confined to Africa, while T. cyclops, from an Asian primate appears to have evolved separately and is placed in a clade with T. (Megatrypanum species. Relating clade taxon composition to palaeogeographic evidence, the divergence of T. brucei and T. cruzi can be dated to the mid-Cretaceous, around 100 million years before present, following the separation of Africa, South America and Euramerica. Such an estimate of divergence time is considerably more recent than those of most previous studies based on molecular clock methods. Perhaps significantly, Salivarian trypanosomes appear, from these data, to be evolving several times faster than Schizotrypanum species, a factor which may have contributed to previous anomalous estimates of divergence times.

  14. Antioxidant Therapy Against Trypanosome Infections: A Review Update.

    Science.gov (United States)

    Ibrahim, Mohammed Auwal; Bindawa Isah, Murtala; Abdullahi Salman, Abdulmalik

    2016-01-01

    Trypanosomiasis is a serious parasitic disease that affects humans and animals resulting in heavy health and economic burdens. Disturbance of redox equilibrium represents a classical challenge for both the host and the parasite during infections with either extracellular African or intracellular American trypanosomes species. This is in spite of existing detoxification mechanisms in both the host and the parasite for maintaining oxidative balance. However, oxidative stress still plays vital roles in the induction of numerous host-associated pathological damages such as anemia, hepatic and renal damages as well as cardiomyopathy while on the other hand, drugs that specifically induce oxidative stress to the parasite have been effective. Therefore, antioxidants have been deemed to play a role in modulating trypanosome infections. This review provides a current update on most of the studies conducted on the potential use of antioxidants as therapeutic agents against trypanosomes. The most frequently studied plant-derived phenolic antioxidants are resveratrol, cucurmin, gallic acid and quercetin while other antioxidants such as vitamins (A, C, E) and trace elements (selenium and iron) have been investigated. Some of the investigations monitored the direct trypanocidal or trypanostatic effects of the antioxidants while others studied the potentials of the antioxidants as adjuncts to trypanocidal drugs. So far, none of these approaches has sufficient data to allow a definite statement on the actual therapeutic potential of antioxidants in the treatment of clinical trypanosomiasis. Therefore, suggestions are made on the most therapeutically and clinically relevant role of antioxidants in trypanosome infections. PMID:27072713

  15. Traversal time for tunnelling

    International Nuclear Information System (INIS)

    We give here a simple approach to study the traversal time for tunnelling. We make use of the WKB wave functions to evaluate the velocity field of particles in the barrier region and obtain an expression for traversal time given by ∫dx[m/2(V(x)-E)]sup(1/2). This coincides with the expression given by recent approaches which determine traversal time by studying transmission of particles through a time-modulated rectangular barrier and by studying the extent of Larmor precession of particles through a rectangular barrier in the presence of a magnetic field. (author)

  16. The evolution of pathogenic trypanosomes

    Directory of Open Access Journals (Sweden)

    Jamie R. Stevens

    1999-10-01

    Full Text Available In the absence of a fossil record, the evolution of protozoa has until recently largely remained a matter for speculation. However, advances in molecular methods and phylogenetic analysis are now allowing interpretation of the "history written in the genes". This review focuses on recent progress in reconstruction of trypanosome phylogeny based on molecular data from ribosomal RNA, the miniexon and protein-coding genes. Sufficient data have now been gathered to demonstrate unequivocally that trypanosomes are monophyletic; the phylogenetic trees derived can serve as a framework to reinterpret the biology, taxonomy and present day distribution of trypanosome species, providing insights into the coevolution of trypanosomes with their vertebrate hosts and vectors. Different methods of dating the divergence of trypanosome lineages give rise to radically different evolutionary scenarios and these are reviewed. In particular, the use of one such biogeographically based approach provides new insights into the coevolution of the pathogens, Trypanosoma brucei and Trypanosoma cruzi, with their human hosts and the history of the diseases with which they are associated.

  17. Phantom energy traversable wormholes

    International Nuclear Information System (INIS)

    It has been suggested that a possible candidate for the present accelerated expansion of the Universe is 'phantom energy'. The latter possesses an equation of state of the form ω≡p/ρ<-1, consequently violating the null energy condition. As this is the fundamental ingredient to sustain traversable wormholes, this cosmic fluid presents us with a natural scenario for the existence of these exotic geometries. 'Note, however, that the notion of phantom energy is that of a homogeneously distributed fluid. Nevertheless, it can be extended to inhomogeneous spherically symmetric spacetimes, and it is shown that traversable wormholes may be supported by phantom energy. Because of the fact of the accelerating Universe, macroscopic wormholes could naturally be grown from the submicroscopic constructions that originally pervaded the quantum foam. One could also imagine an advanced civilization mining the cosmic fluid for phantom energy necessary to construct and sustain a traversable wormhole. In this context, we investigate the physical properties and characteristics of traversable wormholes constructed using the equation of state p=ωρ, with ω<-1. We analyze specific wormhole geometries, considering asymptotically flat spacetimes and imposing an isotropic pressure. We also construct a thin shell around the interior wormhole solution, by imposing the phantom energy equation of state on the surface stresses. Using the 'volume integral quantifier' we verify that it is theoretically possible to construct these geometries with vanishing amounts of averaged null energy condition violating phantom energy. Specific wormhole dimensions and the traversal velocity and time are also deduced from the traversability conditions for a particular wormhole geometry. These phantom energy traversable wormholes have far-reaching physical and cosmological implications. For instance, an advanced civilization may use these geometries to induce closed timelike curves, consequently violating

  18. Phantom energy traversable wormholes

    CERN Document Server

    Lobo, F S N

    2005-01-01

    It has been suggested that a possible candidate for the present accelerated expansion of the Universe is ''phantom energy''. The latter possesses an equation of state of the form $\\omega\\equiv p/\\rho<-1$, consequently violating the null energy condition. As this is the fundamental ingredient to sustain traversable wormholes, this cosmic fluid presents us with a natural scenario for the existence of these exotic geometries. Due to the fact of the accelerating Universe, macroscopic wormholes could naturally be grown from the submicroscopic constructions that originally pervaded the quantum foam. One could also imagine an advanced civilization mining the cosmic fluid for phantom energy necessary to construct and sustain a traversable wormhole. In this context, we investigate the physical properties and characteristics of traversable wormholes constructed using the equation of state $p=\\omega \\rho$, with $\\omega<-1$. We analyze specific wormhole geometries, considering asymptotically flat spacetimes and imp...

  19. Traversing psychological distance.

    Science.gov (United States)

    Liberman, Nira; Trope, Yaacov

    2014-07-01

    Traversing psychological distance involves going beyond direct experience, and includes planning, perspective taking, and contemplating counterfactuals. Consistent with this view, temporal, spatial, and social distances as well as hypotheticality are associated, affect each other, and are inferred from one another. Moreover, traversing all distances involves the use of abstraction, which we define as forming a belief about the substitutability for a specific purpose of subjectively distinct objects. Indeed, across many instances of both abstraction and psychological distancing, more abstract constructs are used for more distal objects. Here, we describe the implications of this relation for prediction, choice, communication, negotiation, and self-control. We ask whether traversing distance is a general mental ability and whether distance should replace expectancy in expected-utility theories. PMID:24726527

  20. The Social Life of African Trypanosomes.

    Science.gov (United States)

    Imhof, Simon; Roditi, Isabel

    2015-10-01

    The unicellular parasite Trypanosoma brucei shuttles between its definitive host, the tsetse fly, and various mammals including humans. In the fly digestive tract, T. brucei must first migrate to the ectoperitrophic space, establish a persistent infection of the midgut and then migrate to the salivary glands before being transmitted to a new mammalian host. In 2010, it was shown that insect stages of the parasite (procyclic forms) exhibit social motility (SoMo) when cultured on a semi-solid surface, and it was postulated that this behaviour might reflect a migration step in the tsetse fly. Now, almost 5 years after the initial report, several new publications shed some light on the biological function of SoMo and provide insights into the underlying signalling pathways. PMID:26433252

  1. Apparatus for obstacle traversion

    Science.gov (United States)

    Borenstein, Johann

    2004-08-10

    An apparatus for traversing obstacles having an elongated, round, flexible body that includes a plurality of drive track assemblies. The plurality of drive track assemblies cooperate to provide forward propulsion wherever a propulsion member is in contact with any feature of the environment, regardless of how many or which ones of the plurality of drive track assemblies make contact with such environmental feature.

  2. Molecular diagnosis of Trypanosome species

    International Nuclear Information System (INIS)

    Various parameters for handling samples, extracting nucleic acid and protocols for use of PCR to diagnose trypanosomes have been examined. The use of a commercial kit (Nucleon BACC 2, Amersham) was superior to other extraction methods. After comparisons, a touchdown thermocycling protocol was the procedure used. PCR testing protocols were successfully implemented using Kin primers that bind to an internal transcribed spacer region (ITS1) situated between the 18S and the 5.8S ribosomal subunit genes on nuclear DNA. Their sensitivity was lower than that of satellite DNA primers, particularly for T.vivax. A Kin primer-based PCR could detect and distinguish between a number of Trypanosome species in blood samples. The use of an ITS1 binding primer was 3-5 x cheaper than using classical species-specific primers since the number of PCR reactions per sample is reduced to one. (author)

  3. Conformally symmetric traversable wormholes

    International Nuclear Information System (INIS)

    Exact solutions of traversable wormholes are found under the assumption of spherical symmetry and the existence of a nonstatic conformal symmetry, which presents a more systematic approach in searching for exact wormhole solutions. In this work, a wide variety of solutions are deduced by considering choices for the form function, a specific linear equation of state relating the energy density and the pressure anisotropy, and various phantom wormhole geometries are explored. A large class of solutions impose that the spatial distribution of the exotic matter is restricted to the throat neighborhood, with a cutoff of the stress-energy tensor at a finite junction interface, although asymptotically flat exact solutions are also found. Using the 'volume integral quantifier', it is found that the conformally symmetric phantom wormhole geometries may, in principle, be constructed by infinitesimally small amounts of averaged null energy condition violating matter. Considering the tidal acceleration traversability conditions for the phantom wormhole geometry, specific wormhole dimensions and the traversal velocity are also deduced

  4. Term rewriting with traversal functions

    NARCIS (Netherlands)

    Vinju, J.J.; Brand, M.G.J. van den; Klint, P.

    2003-01-01

    Term rewriting is an appealing technique for performing program analysis and program transformation. Tree (term) traversal is frequently used but is not supported by standard term rewriting. We extend many-sorted, first-order term rewriting with traversal functions that automate tree traversal in a

  5. The Gremlin Graph Traversal Machine and Language

    OpenAIRE

    Rodriguez, Marko A.

    2015-01-01

    Gremlin is a graph traversal machine and language designed, developed, and distributed by the Apache TinkerPop project. Gremlin, as a graph traversal machine, is composed of three interacting components: a graph $G$, a traversal $\\Psi$, and a set of traversers $T$. The traversers move about the graph according to the instructions specified in the traversal, where the result of the computation is the ultimate locations of all halted traversers. A Gremlin machine can be executed over any suppor...

  6. Phosphatidylethanolamine is the donor of the terminal phosphoethanolamine group in trypanosome glycosylphosphatidylinositols.

    OpenAIRE

    Menon, A K; Eppinger, M.; Mayor, S.; Schwarz, R T

    1993-01-01

    A variety of eukaryotic cell surface proteins, including the variant surface glycoproteins of African trypanosomes, rely on a covalently attached lipid, glycosylphosphatidylinositol (GPI), for membrane attachment. GPI anchors are synthesized in the endoplasmic reticulum by stepwise glycosylation of phosphatidylinositol (via UDP-GlcNAc and dolichol-P-mannose) followed by the addition of phosphoethanolamine. The experiments described in this paper are aimed at identifying the biosynthetic origi...

  7. Gravitational perturbation of traversable wormhole

    OpenAIRE

    Kim, Sung-Won

    2004-01-01

    In this paper, we study the perturbation problem of the scalar, electromagnetic, and gravitational waves under the traversable Lorentzian wormhole geometry. The unified form of the potential for the Schr\\"odinger type one-dimensional wave equation is found.

  8. An Investigation of the Laws of Traversals

    CERN Document Server

    Jaskelioff, Mauro; 10.4204/EPTCS.76.5

    2012-01-01

    Traversals of data structures are ubiquitous in programming. Consequently, it is important to be able to characterise those structures that are traversable and understand their algebraic properties. Traversable functors have been characterised by McBride and Paterson as those equipped with a distributive law over arbitrary applicative functors; however, laws that fully capture the intuition behind traversals are missing. This article is an attempt to remedy this situation by proposing laws for characterising traversals that capture the intuition behind them. To support our claims, we prove that finitary containers are traversable in our sense and argue that elements in a traversable structure are visited exactly once.

  9. Adult blood-feeding tsetse flies, trypanosomes, microbiota and the fluctuating environment in sub-Saharan Africa

    OpenAIRE

    Geiger, Anne; Ponton, F; Simo, G.

    2015-01-01

    The tsetse fly vector transmits the protozoan Trypanosoma brucei, responsible for Human African Trypanosomiasis, one of the most neglected tropical diseases. Despite a recent decline in new cases, it is still crucial to develop alternative strategies to combat this disease. Here, we review the literature on the factors that influence trypanosome transmission from the fly vector to its vertebrate host (particularly humans). These factors include climate change effects to pathogen and vector de...

  10. Gravity's Rainbow and Traversable Wormholes

    CERN Document Server

    Garattini, Remo

    2015-01-01

    In the context of Gravity's Rainbow, we compute the graviton one-loop contribution to a classical energy in a traversable wormhole background, by considering the equation of state $p_{r} = \\omega\\rho$. The investigation is evaluated by means of a variational approach with Gaussian trial wave functionals. However, instead of using a regularization/renormalization process, we use the distortion induced by Gravity's Rainbow to handle the divergences.

  11. Automatically Optimizing Tree Traversal Algorithms

    OpenAIRE

    Jo, Youngjoon

    2013-01-01

    Many domains in computer science, from data-mining to graphics to computational astrophysics, focus heavily on irregular applications. In contrast to regular applications, which operate over dense matrices and arrays, irregular programs manipulate and traverse complex data structures like trees and graphs. As irregular applications operate on ever larger datasets, their performance suffers from poor locality and parallelism. Programmers are burdened with the arduous task of manually tuning su...

  12. Protein - Trypanosomes Database | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available [ Credit s ] BLAST Search Image Search Home About Archive Update History Contact us Trypanosomes ... ail Data name Protein Description of data contents It ... is a summaly table of protein information; such as ... otein. There is also information of candidate inhibit or of the protein. Data file File name: trypanosome ... ciencedbc.jp/togodb/view/trypanosome#en Data acquisit ion method - Data analysis method - Number of data ... entries 17 entries Data it em Description symbol Symbol of the protein name Na ...

  13. [Detection of trypanosomes in blood by the Quantitative Buffy Coat (QBC) technique: experimental evaluation].

    Science.gov (United States)

    Ancelle, T; Paugam, A; Bourlioux, F; Merad, A; Vigier, J P

    1997-01-01

    Microhematocrit centrifugation (Woo test) and miniature anion exchange are the most widely used techniques for routine detection of Trypanosoma brucei gambiense in endemic areas. The QBC technique developed for diagnosis of malaria has been successfully used for detection of trypanosoma in blood. The purpose of this laboratory study was to evaluate the end-point sensitivity of the QBC test in comparison with the Woo test. Decreasing concentrations from 15 x 10(5) to 15 trypanosomes/ml of human blood were tested using the two techniques. Sensitivity was calculated in function of reading time at each concentration. Results showed that the sensitivity of the QBC test was 95% down to a concentration of 450 trypanosomes/ml. In comparison 95% sensitivity of the Woo test was observed only down to 7500 trypanosomes/ml and reading time was twofold longer. These findings were reproducible for two hours after sample preparation but deterioration was rapid thereafter. Given its simplicity and sensitivity, QBC test would appear to be a suitable technique for in-field screening programs for human African trypanosomiasis. PMID:9513149

  14. Traversable Wormholes in Distorted Gravity

    CERN Document Server

    Garattini, Remo

    2015-01-01

    We consider the effects of Distorted Gravity on the traversability of the wormholes. In particular, we consider configurations which are sustained by their own gravitational quantum fluctuations. The Ultra-Violet divergences appearing to one loop are taken under control with the help of a Noncommutative geometry representation and Gravity's Rainbow. In this context, it will be shown that for every framework, the self-sustained equation will produce a Wheeler wormhole, namely a wormhole of Planckian size. This means that, from the point of view of traversability, the wormhole will be traversable in principle, but not in practice. To this purpose, in the context of Gravity's Rainbow we have considered different proposals of rainbow's functions to see if the smallness of the wormhole is dependent on the chosen form of the rainbow's function. Unfortunately, we discover that this is not the case and we suggest that the self-sustained equation can be improved to see if the wormhole radius can be enlarged or not. So...

  15. TRAVERSAL ALGORITHM FOR COMPLETE COVERAGE

    Directory of Open Access Journals (Sweden)

    Coimbatore Ganeshsankar Balaji

    2012-01-01

    Full Text Available There are many applications which require complete coverage and obstacle avoidance. The classical A* algorithm provides the user a shortest path by avoiding the obstacle. As well, the Dijkstra’s algorithm finds the shortest path between the source and destination. But in many applications we require complete coverage of the proposed area with obstacle avoidance. There are LSP, LSSP, BSA, spiral-STC and Complete Coverage D* algorithms which do not realize complete (100% coverage. The complete coverage using a critical point algorithm assures complete coverage, but it is not well suited for applications like mine detection. Also for covering the missed region it keeps the obstacle as a critical point which is not advisable in critical applications where obstacle may be a dangerous one. To overcome this and to achieve the complete coverage we propose a novel graph traversal algorithm Traversal Algorithm for Complete Coverage (TRACC. Here the area to be scanned is decomposed into a finite number of cells. The traversal is done through all the cells after making sure the next cell has no obstacle. TRACC assures thorough coverage of the proposed area and ensuring that all the obstacles are avoided. Hence the TRACC always have the safer path while covering the entire area. It also reports the obstacle placed or blocked cell.

  16. The trypanosome Pumilio domain protein PUF5.

    Science.gov (United States)

    Jha, Bhaskar Anand; Archer, Stuart K; Clayton, Christine E

    2013-01-01

    PUF proteins are a conserved family of RNA binding proteins found in all eukaryotes examined so far. This study focussed on PUF5, one of 11 PUF family members encoded in the Trypanosoma brucei genome. Native PUF5 is present at less than 50000 molecules per cell in both bloodstream and procyclic form trypanosomes. C-terminally myc-tagged PUF5 was mainly found in the cytoplasm and could be cross-linked to RNA. PUF5 knockdown by RNA interference had no effect on the growth of bloodstream forms. Procyclic forms lacking PUF5 grew normally, but expression of PUF5 bearing a 21 kDa tandem affinity purification tag inhibited growth. Knockdown of PUF5 did not have any effect on the ability of trypanosomes to differentiate from the mammalian to the insect form of the parasite. PMID:24167571

  17. Five dimensional cosmological traversable wormhole

    Energy Technology Data Exchange (ETDEWEB)

    Najafi, S.; Rostami, T., E-mail: t_rostami@sbu.ac.ir; Jalalzadeh, S., E-mail: s-jalalzadeh@sbu.ac.ir

    2015-03-15

    In this paper, a traversable wormhole in the Friedmann–Lemaître–Robertson–Walker (FLRW) model with one extra spacelike compact dimension is studied. We have chosen dynamical compactification as the evolution of the fifth dimension. In this respect, we study how the existence of the extra dimension affects the behavior of the energy density, the shape function and the scale factor. It is shown that the total matter can be non-exotic and the violation of the weak energy condition can be avoided.

  18. Mechanism of Trypanosoma brucei gambiense (group 1) resistance to human trypanosome lytic factor.

    Science.gov (United States)

    Kieft, Rudo; Capewell, Paul; Turner, C Michael R; Veitch, Nicola J; MacLeod, Annette; Hajduk, Stephen

    2010-09-14

    Human innate immunity against most African trypanosomes, including Trypanosoma brucei brucei, is mediated by a minor subclass of toxic serum HDL, called trypanosome lytic factor-1 (TLF-1). This HDL contains two primate specific proteins, apolipoprotein L-1 and haptoglobin (Hp)-related protein, as well as apolipoprotein A-1. These assembled proteins provide a powerful defense against trypanosome infection. Trypanosoma brucei rhodesiense causes human African sleeping sickness because it has evolved an inhibitor of TLF-1, serum resistance-associated (SRA) protein. Trypanosoma brucei gambiense lacks the SRA gene, yet it infects humans. As transfection of T. b. gambiense (group 1) is not possible, we initially used in vitro-selected TLF-1-resistant T. b. brucei to examine SRA-independent mechanisms of TLF-1 resistance. Here we show that TLF-1 resistance in T. b. brucei is caused by reduced expression of the Hp/Hb receptor gene (TbbHpHbR). Importantly, T. b. gambiense (group 1) also showed a marked reduction in uptake of TLF-1 and a corresponding decrease in expression of T. b. gambiense Hp/Hb receptor (TbgHpHbR). Ectopic expression of TbbHpHbR in TLF-1-resistant T. b. brucei rescued TLF-1 uptake, demonstrating that decreased TbbHpHbR expression conferred TLF-1 resistance. Ectopic expression of TbgHpHbR in TLF-1-resistant T. b. brucei failed to rescue TLF-1 killing, suggesting that coding sequence changes altered Hp/Hb receptor binding affinity for TLF-1. We propose that the combination of coding sequence mutations and decreased expression of TbgHpHbR directly contribute to parasite evasion of human innate immunity and infectivity of group 1 T. b. gambiense. PMID:20805508

  19. Trypanosome lytic factor, an antimicrobial high-density lipoprotein, ameliorates Leishmania infection.

    Directory of Open Access Journals (Sweden)

    Marie Samanovic

    2009-01-01

    Full Text Available Innate immunity is the first line of defense against invading microorganisms. Trypanosome Lytic Factor (TLF is a minor sub-fraction of human high-density lipoprotein that provides innate immunity by completely protecting humans from infection by most species of African trypanosomes, which belong to the Kinetoplastida order. Herein, we demonstrate the broader protective effects of human TLF, which inhibits intracellular infection by Leishmania, a kinetoplastid that replicates in phagolysosomes of macrophages. We show that TLF accumulates within the parasitophorous vacuole of macrophages in vitro and reduces the number of Leishmania metacyclic promastigotes, but not amastigotes. We do not detect any activation of the macrophages by TLF in the presence or absence of Leishmania, and therefore propose that TLF directly damages the parasite in the acidic parasitophorous vacuole. To investigate the physiological relevance of this observation, we have reconstituted lytic activity in vivo by generating mice that express the two main protein components of TLFs: human apolipoprotein L-I and haptoglobin-related protein. Both proteins are expressed in mice at levels equivalent to those found in humans and circulate within high-density lipoproteins. We find that TLF mice can ameliorate an infection with Leishmania by significantly reducing the pathogen burden. In contrast, TLF mice were not protected against infection by the kinetoplastid Trypanosoma cruzi, which infects many cell types and transiently passes through a phagolysosome. We conclude that TLF not only determines species specificity for African trypanosomes, but can also ameliorate an infection with Leishmania, while having no effect on T. cruzi. We propose that TLFs are a component of the innate immune system that can limit infections by their ability to selectively damage pathogens in phagolysosomes within the reticuloendothelial system.

  20. The Trypanosome Pumilio Domain Protein PUF5

    OpenAIRE

    Jha, Bhaskar Anand; Archer, Stuart K.; Clayton, Christine E.

    2013-01-01

    PUF proteins are a conserved family of RNA binding proteins found in all eukaryotes examined so far. This study focussed on PUF5, one of 11 PUF family members encoded in the Trypanosoma brucei genome. Native PUF5 is present at less than 50000 molecules per cell in both bloodstream and procyclic form trypanosomes. C-terminally myc-tagged PUF5 was mainly found in the cytoplasm and could be cross-linked to RNA. PUF5 knockdown by RNA interference had no effect on the growth of bloodstream forms. ...

  1. Traversable wormholes the Roman ring

    CERN Document Server

    Visser, M

    1997-01-01

    In this brief report I introduce a yet another class of geometries for which semi-classical chronology protection theorems are of dubious physical reliability. I consider a ``Roman ring'' of traversable wormholes, wherein a number of wormholes are arranged in a ring in such a manner that no subset of wormholes is near to chronology violation, though the combined system can be arbitrarily close to chronology violation. I show that (with enough wormholes in the ring) the gravitational vacuum polarization (the expectation value of the quantum stress-energy tensor) can be made arbitrarily small. In particular the back-reaction can be kept arbitrarily small all the way to the ``reliability horizon''---so that semi-classical quantum gravity becomes unreliable before the gravitational back reaction becomes large.

  2. Axially symmetric rotating traversable wormholes

    CERN Document Server

    Kuhfittig, P K F

    2003-01-01

    This paper generalizes the static and spherically symmetric traversable wormhole geometry to a rotating axially symmetric one with a time-dependent angular velocity by means of an exact solution. It was found that the violation of the weak energy condition, although unavoidable, is considerably less severe than in the static spherically symmetric case. The radial tidal constraint is more easily met due to the rotation. Similar improvements are seen in one of the lateral tidal constraints. The magnitude of the angular velocity may have little effect on the weak energy condition violation for an axially symmetric wormhole. For a spherically symmetric one, however, the violation becomes less severe with increasing angular velocity. The time rate of change of the angular velocity, on the other hand, was found to have no effect at all. Finally, the angular velocity must depend only on the radial coordinate, confirming an earlier result.

  3. The molecular basis of livestock disease as illustrated by African trypanosomiasis

    International Nuclear Information System (INIS)

    African trypanosomes are protozoan parasites, most species of which are transmitted by tsetse flies. They reside in the mammalian bloodstream and evade the immune system by periodically switching the major protein on their surface - a phenomenon called antigenic variation, mediated by gene rearrangements in the trypanosome genome. The trypanosomes eventually enter the central nervous system and cause a fatal disease, commonly called ngana in domestic cattle and sleeping sickness in humans. Two sub-species of Trypanosoma brucei infect humans (T. b. rhodesiense and T. b. gambiense) and one sub-species does not survive in humans (T. b. brucei) because it is lysed by the human-specific serum protein, apolipoprotein L-I. Wild animals in Africa have other (less well understood) molecular mechanisms of suppressing the number of African trypanosomes in the blood, and some indigenous breeds of African cattle also display a partial 'trypanotolerance' whose genetic loci have recently been mapped. (author)

  4. Anuran trypanosomes: phylogenetic evidence for new clades in Brazil.

    Science.gov (United States)

    da S Ferreira, Juliana I G; da Costa, Andrea P; Ramirez, Diego; Roldan, Jairo A M; Saraiva, Danilo; da S Founier, Gislene F R; Sue, Ana; Zambelli, Erick R; Minervino, Antonio H H; Verdade, Vanessa K; Gennari, Solange M; Marcili, Arlei

    2015-05-01

    Trypanosomes of anurans and fish are grouped into the Aquatic Clade which includes species isolated from fish, amphibians, turtles and platypus, usually transmitted by leeches and phlebotomine sand flies. Trypanosomes from Brazilian frogs are grouped within the Aquatic Clade with other anuran trypanosome species, where there seems to be coevolutionary patterns with vertebrate hosts and association to Brazilian biomes (Atlantic Forest, Pantanal and Amazonia Rainforest). We characterised the anuran trypanosomes from two different areas of the Cerrado biome and examined their phylogenetic relationships based on the SSU rRNA gene. A total of 112 anurans of six species was analysed and trypanosome prevalence evaluated through haemoculture was found to be 7% (8 positive frogs). However, only three isolates (2.7%) from two anuran species were recovered and cryopreserved. Analysis including SSU rDNA sequences from previous studies segregated the anuran trypanosomes into six groups, the previously reported An01 to An04, and An05 and An06 reported herein. Clade An05 comprises the isolates from Leptodactylus latrans (Steffen) and Pristimantis sp. captured in the Cerrado biome and Trypanosoma chattoni Mathis & Leger, 1911. The inclusion of new isolates in the phylogenetic analyses provided evidence for a new group (An06) of parasites from phlebotomine hosts. Our results indicate that the diversity of trypanosome species is underestimated since studies conducted in Brazil and other regions of the world are still few. PMID:25862033

  5. Fully Traversable Wormholes Hiding Charge

    CERN Document Server

    Guendelman, Eduardo

    2012-01-01

    The charge-hiding effect by a wormhole, which was studied for the case where gravity/gauge-field system is self-consistently interacting with a charged lightlike brane (LLB) as a matter source, is now studied for the case of a time like brane. From the demand that no surfaces of infinite coordinate time redshift appear in the problem we are lead now to a completly traversable wormhole space, according to not only the traveller that goes through the wormhole (as was the case for the LLB), but also to a static external observer, this requires negative surface energy density for the shell sitting at the throat of the wormhole. We study a gauge field subsystem which is of a special non-linear form containing a square-root of the Maxwell term and which previously has been shown to produce a QCD-like confining gauge field dynamics in flat space-time. The condition of finite energy of the system or asymptotic flatness on one side of the wormhole implies that the charged object sitting at the wormhole throat expels a...

  6. Flagellum ontogeny in trypanosomes studied via an inherited and regulated RNA interference system.

    Science.gov (United States)

    Bastin, P; Ellis, K; Kohl, L; Gull, K

    2000-09-01

    The African trypanosome, Trypanosoma brucei possesses a large and unique intraflagellar structure called the paraflagellar rod (PFR). The PFR is composed of 2 major proteins, PFRA and PFRC. We have generated an inducible mutant trypanosome cell line (snl-2) that expresses linked inverted copies of a PFRA gene, capable of forming a PFRA double-stranded (ds) RNA. When expression of this dsRNA was induced, new PFRA RNA and PFRA protein quickly disappeared and PFR construction was affected, resulting in cell paralysis. This inducible RNA interference (RNAi) effect was fast-acting, heritable and reversible. It allowed us to demonstrate that PFR proteins are able to enter both mature and growing flagella but appear to concentrate differentially in new flagella because of the construction process. The PFR is constructed by a polar assembly process at the distal end of the flagellum resulting in a stable cytoskeletal structure with low turn-over. The inducible RNAi approach will have widespread applicability in studies of gene function and cellular processes in parasites. PMID:10954429

  7. RTSAH Traversal Order for Occlusion Rays

    KAUST Repository

    Ize, Thiago

    2011-04-01

    We accelerate the finding of occluders in tree based acceleration structures, such as a packetized BVH and a single ray kd-tree, by deriving the ray termination surface area heuristic (RTSAH) cost model for traversing an occlusion ray through a tree and then using the RTSAH to determine which child node a ray should traverse first instead of the traditional choice of traversing the near node before the far node. We further extend RTSAH to handle materials that attenuate light instead of fully occluding it, so that we can avoid superfluous intersections with partially transparent objects. For scenes with high occlusion, we substantially lower the number of traversal steps and intersection tests and achieve up to 2× speedups. © 2010 The Author(s).

  8. Anti-trypanosomal Activity of Potential Inhibitors of Trypanosoma brucei Glycolytic Pathway Enzymes Selected by Docking Studies

    Directory of Open Access Journals (Sweden)

    Clarisse Musanabaganwa

    2014-12-01

    Full Text Available Human African trypanosomiasis (HAT, a potentially fatal protozoan infection caused by tsetse-fl mediated transmission of Trypanosoma brucei (T. Brucei, is largely recognized as a neglected disease. The repertoire of drugs that is effective against the infection is limited and all drugs have several drawbacks including high level of toxicity, diffiult administration regimens, and the resurgence of resistance. At present the biology of the parasite is well studied and a number of technologies are now available which can aid in the identifiation of potential drug targets. This review identifies putative inhibitors of trypanosomal glycolytic enzymes.

  9. Trypanosome infection establishment in the tsetse fly gut is influenced by microbiome-regulated host immune barriers.

    Directory of Open Access Journals (Sweden)

    Brian L Weiss

    Full Text Available Tsetse flies (Glossina spp. vector pathogenic African trypanosomes, which cause sleeping sickness in humans and nagana in domesticated animals. Additionally, tsetse harbors 3 maternally transmitted endosymbiotic bacteria that modulate their host's physiology. Tsetse is highly resistant to infection with trypanosomes, and this phenotype depends on multiple physiological factors at the time of challenge. These factors include host age, density of maternally-derived trypanolytic effector molecules present in the gut, and symbiont status during development. In this study, we investigated the molecular mechanisms that result in tsetse's resistance to trypanosomes. We found that following parasite challenge, young susceptible tsetse present a highly attenuated immune response. In contrast, mature refractory flies express higher levels of genes associated with humoral (attacin and pgrp-lb and epithelial (inducible nitric oxide synthase and dual oxidase immunity. Additionally, we discovered that tsetse must harbor its endogenous microbiome during intrauterine larval development in order to present a parasite refractory phenotype during adulthood. Interestingly, mature aposymbiotic flies (Gmm(Apo present a strong immune response earlier in the infection process than do WT flies that harbor symbiotic bacteria throughout their entire lifecycle. However, this early response fails to confer significant resistance to trypanosomes. Gmm(Apo adults present a structurally compromised peritrophic matrix (PM, which lines the fly midgut and serves as a physical barrier that separates luminal contents from immune responsive epithelial cells. We propose that the early immune response we observe in Gmm(Apo flies following parasite challenge results from the premature exposure of gut epithelia to parasite-derived immunogens in the absence of a robust PM. Thus, tsetse's PM appears to regulate the timing of host immune induction following parasite challenge. Our results

  10. Chaperone requirements for biosynthesis of the trypanosome variant surface glycoprotein.

    Directory of Open Access Journals (Sweden)

    Mark C Field

    Full Text Available BACKGROUND: Trypanosoma brucei does not respond transcriptionally to several endoplasmic reticulum (ER stress conditions, including tunicamycin or dithiothreitol, indicating the absence of a conventional unfolded protein response. This suggests divergent mechanisms for quality control (QC of ER protein folding and export may be present in trypanosomes. As the variant surface glycoprotein (VSG represents approximately 90% of trypanosome plasma membrane protein, it is possible that VSG has evolved to fold efficiently to minimize ER folding burden. METHODOLOGY/PRINCIPAL FINDINGS: We demonstrate the presence of a QC system by pharmacological inhibition of the trypanosome 26S proteasome. This indicates active proteasome-mediated VSG turnover as approximately 2.5 fold more VSG is recovered from cell lysates following MG132 inhibition. An in silico scan of the trypanosome genome identified 28 open reading frames likely to encode polypeptides participating in ER nascent chain maturation. By RNA interference we monitored the importance of these gene products to proliferation, VSG abundance and cell morphology. 68% of the cohort were required for normal proliferation, and depletion of most of these factors resulted in increased VSG abundance, suggesting involvement in ERQC and degradation. CONCLUSIONS/SIGNIFICANCE: The retention of genes for, and the involvement of many gene products in, VSG folding indicates a substantial complexity within the pathways required to perform this role. Counterintuitively, for a super-abundant antigen VSG is apparently made in excess. The biosynthetic excess VSG appears to be turned over efficiently by the proteasome, implying that considerable VSG is rejected by the trypanosome ERQC mechanism. Accordingly, the VSG polypeptide is not well optimized for folding, as only approximately 30% attains the native state. Finally as much of the core ERQC system is functionally conserved in trypanosomes, the pathway has an ancient

  11. Express route between Frankfort and Traverse City

    OpenAIRE

    Embrey, Shaan-Mya; Falenius, Sofie

    2012-01-01

    Since 2007 Benzie Bus has operated public transportation in Benzie County, Michigan. Benzie County is a rural area with a lot of people commuting every day to Traverse City for work and education. At present the company mainly operates a Dial-a-Ride system, but also a route between Frankfort and Traverse City three times a day Monday to Friday. Only a few of these commuters travel by public transportation today and a large reason is that the trip takes too long, mainly because of a high servi...

  12. Traversable Wormholes via a Double Trace Deformation

    CERN Document Server

    Gao, Ping; Wall, Aron

    2016-01-01

    After turning on an interaction that couples the two boundaries of an eternal BTZ black hole, we find a quantum matter stress tensor with negative average null energy, whose gravitational backreaction renders the Einstein-Rosen bridge traversable. Such a traversable wormhole has an interesting interpretation in the context of ER=EPR, which we suggest might be related to quantum teleportation. However, it cannot be used to violate causality. We also discuss the implications for the energy and holographic entropy in the dual CFT description.

  13. Sexual differences in prevalence of a new species of trypanosome infecting túngara frogs.

    Science.gov (United States)

    Bernal, Ximena E; Pinto, C Miguel

    2016-04-01

    Trypanosomes are a diverse group of protozoan parasites of vertebrates transmitted by a variety of hematophagous invertebrate vectors. Anuran trypanosomes and their vectors have received relatively little attention even though these parasites have been reported from frog and toad species worldwide. Blood samples collected from túngara frogs (Engystomops pustulosus), a Neotropical anuran species heavily preyed upon by eavesdropping frog-biting midges (Corethrella spp.), were examined for trypanosomes. Our results revealed sexual differences in trypanosome prevalence with female frogs being rarely infected (frog-biting midges that find their host using the mating calls produced by male frogs. Following previous anuran trypanosome studies, we examined 18S ribosomal RNA gene to characterize and establish the phylogenetic relationship of the trypanosome species found in túngara frogs. A new species of giant trypanosome, Trypanosoma tungarae n. sp., is described in this study. Overall the morphometric data revealed that the trypomastigotes of T. tungarae n. sp. are similar to other giant trypanosomes such as Trypanosoma rotatorium and Trypanosoma ranarum. Despite its slender and long cell shape, however, 18S rRNA gene sequences revealed that T. tungarae n. sp. is sister to the rounded-bodied giant trypanosome, Trypanosoma chattoni. Therefore, morphological convergence explains similar morphology among members of two non-closely related groups of trypanosomes infecting frogs. The results from this study underscore the value of coupling morphological identification with molecular characterization of anuran trypanosomes. PMID:26977404

  14. The traversable wormhole with classical scalar fields

    OpenAIRE

    Kim, S. -W; Kim, S. P.

    1999-01-01

    We study the Lorentzian static traversable wormholes coupled to quadratic scalar fields. We also obtain the solutions of the scalar fields and matters in the wormhole background and find that the minimal size of the wormhole should be quantized under the appropriate boundary conditions for the positive non-minimal massive scalar field.

  15. High prevalence of trypanosome co-infections in freshwater fishes.

    Science.gov (United States)

    Grybchuk-Ieremenko, Anastasiia; Losev, Alexander; Kostygov, Alexei Yu; Lukeš, Julius; Yurchenko, Vyacheslav

    2014-12-01

    One thousand three hundred seventy three fish specimens of eight different species from the vicinity of Kyiv, Ukraine, were examined for the presence of trypanosomes and 921 individuals were found to be infected. The prevalence of infection ranged from 24% in freshwater bream, Abramis brama (Linnaeus), to 100% in spined loach, Cobitis 'taenia' Linnaeus. The level of parasitaemia also varied significantly between generally mild infections in pikeperch, Sander lucioperca (Linnaeus), and heavy ones in C. 'taenia'. In most cases the infections with trypanosomes were asymptomatic. Cases of co-infection with species of Trypanoplasma Laveran et Mesnil, 1901 were documented for five out of eight examined host species. Molecular analysis of the 18S rDNA sequences revealed that four hosts, namely northern pike, Esox lucius Linnaeus, freshwater bream, spined loach and European perch, Perca fluviatilis Linnaeus, were simultaneously infected with two different trypanosome species. Our findings advocate the view that to avoid the risk posed by mixed infections, subsequent molecular taxonomic studies should be performed on clonal lines derived from laboratory cultures of fish trypanosomes. PMID:25651690

  16. Trypanosome Letm1 protein is essential for mitochondrial potassium homeostasis

    Czech Academy of Sciences Publication Activity Database

    Hashimi, Hassan; McDonald, Lindsay M.; Stříbrná, Eva; Lukeš, Julius

    2013-01-01

    Roč. 288, č. 37 (2013), s. 26914-26925. ISSN 0021-9258 R&D Projects: GA ČR GAP305/12/2261 Institutional support: RVO:60077344 Keywords : Bioenergetics * Letm1 * Mitochondria * Potassium Transport * Translation * Trypanosome Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.600, year: 2013

  17. License - Trypanosomes Database | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available w in using this database. The license for this database is specified in the Creative Commons Attribution-Sha...Trypanosomes DB © Targeted Proteins Research Program licensed under CC Attribution...-Share Alike 2.1 Japan . The summary of the Creative Commons Attribution-Share Alike 2.1 Japan is found her

  18. Traversable wormholes from surgically modified Schwarzschild spacetimes

    CERN Document Server

    Visser, Matt

    2008-01-01

    In this paper I present a new class of traversable wormholes. This is done by surgically grafting two Schwarzschild spacetimes together in such a way that no event horizon is permitted to form. This surgery concentrates a non--zero stress--energy on the boundary layer between the two asymptotically flat regions. I shall investigate this stress--energy in detail using the "junction condition" formalism. A feature of the present analysis is that this class of traversable wormholes is sufficiently simple for a (partial) dynamical stability analysis to be carried out. The stability analysis places constraints on the equation of state of the exotic matter that comprises the throat of the wormhole.

  19. High performance robotic traverse of desert terrain.

    Energy Technology Data Exchange (ETDEWEB)

    Whittaker, William (Carnegie Mellon University, Pittsburgh, PA)

    2004-09-01

    This report presents tentative innovations to enable unmanned vehicle guidance for a class of off-road traverse at sustained speeds greater than 30 miles per hour. Analyses and field trials suggest that even greater navigation speeds might be achieved. The performance calls for innovation in mapping, perception, planning and inertial-referenced stabilization of components, hosted aboard capable locomotion. The innovations are motivated by the challenge of autonomous ground vehicle traverse of 250 miles of desert terrain in less than 10 hours, averaging 30 miles per hour. GPS coverage is assumed to be available with localized blackouts. Terrain and vegetation are assumed to be akin to that of the Mojave Desert. This terrain is interlaced with networks of unimproved roads and trails, which are a key to achieving the high performance mapping, planning and navigation that is presented here.

  20. Role of expression site switching in the development of resistance to human Trypanosome Lytic Factor-1 in Trypanosoma brucei brucei.

    Science.gov (United States)

    Kieft, Rudo; Stephens, Natalie A; Capewell, Paul; MacLeod, Annette; Hajduk, Stephen L

    2012-05-01

    Human high-density lipoproteins (HDLs) play an important role in human innate immunity to infection by African trypanosomes with a minor subclass, Trypanosome Lytic Factor-1 (TLF-1), displaying highly selective cytotoxicity to the veterinary pathogen Trypanosoma brucei brucei but not against the human sleeping sickness pathogens Trypanosoma brucei gambiense or Trypanosoma brucei rhodesiense. T. b. rhodesiense has evolved the serum resistance associated protein (SRA) that binds and confers resistance to TLF-1 while T. b. gambiense lacks the gene for SRA indicating that these parasites have diverse mechanisms of resistance to TLF-1. Recently, we have shown that T. b. gambiense (group 1) resistance to TLF-1 correlated with the loss of the haptoglobin/hemoglobin receptor (HpHbR) expression, the protein responsible for high affinity binding and uptake of TLF-1. In the course of these studies we also examined TLF-1 resistant T. b. brucei cell lines, generated by long-term in vitro selection. We found that changes in TLF-1 susceptibility in T. b. brucei correlated with changes in variant surface glycoprotein (VSG) expression in addition to reduced TLF-1 binding and uptake. To determine whether the expressed VSG or expression site associated genes (ESAGs) contribute to TLF-1 resistance we prepared a TLF-1 resistant T. b. brucei with a selectable marker in a silent bloodstream expression site (BES). Drug treatment allowed rapid selection of trypanosomes that activated the tagged BES. These studies show that TLF-1 resistance in T. b. brucei is largely independent of the expressed VSG or ESAGs further supporting the central role of HpHbR expression in TLF-1 susceptibility in these cells. PMID:22226682

  1. On a macroscopic traversable spacewarp in practice

    OpenAIRE

    Mansouryar, Mohammad

    2005-01-01

    A design of a configuration for violation of the averaged null energy condition (ANEC) and consequently other classic energy conditions (CECs), is presented. The methods of producing effective exotic matter (EM) for a traversable wormhole (TW) are discussed. Also, the approaches of less necessity of TWs to EM are considered. The result is, TW and similar structures; i.e., warp drive (WD) and Krasnikov tube are not just theoretical subjects for teaching general relativity (GR) or objects only ...

  2. Quantifying energy condition violations in traversable wormholes

    Indian Academy of Sciences (India)

    Sayan Kar; Naresh Dadhich; Matt Visser

    2004-10-01

    The `theoretical' existence of traversable Lorentzian wormholes in the classical, macroscopic world is plagued by the violation of the well-known energy conditions of general relativity. In this brief article we show: (i) how the extent of violation can be quantified using certain volume integrals and (ii) whether this `amount of violation' can be minimised for some specific cut-and-paste geometric constructions. Examples and possibilities are also outlined.

  3. Ice Velocities Around the 2000 Meter Traverse in Greenland

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains traverse measurements used to infer the mass balance of central parts of the ice sheet upslope from the traverse, and results from this work...

  4. Database Description - Trypanosomes Database | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available [ Credits ] BLAST Search Image Search Home About Archive Update History Contact us Trypanosomes Database... Database Description General information of database Database name Trypanosomes Database...rmation and Systems Yata 1111, Mishima, Shizuoka 411-8540, JAPAN E mail: Database... classification Protein sequence databases Organism Taxonomy Name: Trypanosoma Taxonomy ID: 5690 Taxonomy Na...me: Homo sapiens Taxonomy ID: 9606 Database description The Trypanosomes database is a database providing th

  5. ASSOCIATION OF TRYPANOSOME INFECTION WITH SPERM ANTIBODIES PRODUCTION IN RED SOKOTO (MARADI GOATS

    Directory of Open Access Journals (Sweden)

    O. FAYEMI

    2006-01-01

    Full Text Available A total of 1021 randomly selected serum samples of adult male goats that had been screened for trypanosome infection were assayed for sperm antibodies using the immunoperoxidase staining technique. The result of the trypanosome screening revealed that 586(57.39% goats were positive for trypanosome infection, while 435(42.61% were negative. The assay for sperm antibodies showed that 482(47.21% animals were positive, while 539(52.79% were negative. In the group that was positive for trypanosome infection, 364(62.12% animals were positive, whereas 222(37.88% were negative for sperm antibodies (P<0.001. The group that was negative for trypanosome infection, had a significantly lower number and proportion 118(27.13% of positive compared to 317(72.87% negative for sperm antibodies. Out of a total 482 goats that were positive for sperm antibodies, a significantly higher number, 364(75.52%, were positive than 118(24.48% that were negative for trypanosome infection (P<0.001. In the group that was found negative for sperm antibodies, a significantly lower proportion, 222(41.19%, was positive compared to 317(58.81% that were negative for trypanosome infection (P<0.001. Seropositivity to sperm antibodies was positively correlated to trypanosome infection (P<0.001. Further work on the pathogenesis of sperm antibody production in trypanosome infection is advocated.

  6. On a macroscopic traversable spacewarp in practice

    CERN Document Server

    Mansouryar, M

    2005-01-01

    A design of a configuration for violation of the averaged null energy condition (ANEC) and consequently other classic energy conditions (CECs), is presented. The meth ods of producing effective exotic matter (EM) for a traversable wormhole (TW) are discussed. Also, the approaches of less necessity of TWs to EM are considered. The result is, TW and similar structures; i.e., warp drive (WD) a nd Krasnikov tube are not just theoretical subjects for teaching general relativity (GR) or objects only an advanced civilization would be able to manufacture anymore, but a quite reachable challenge for current technology. Besides, a new compound metric is introduced as a choice for testing in the lab.

  7. T-transformation: traversability analysis for navigation on rugged terrain

    Science.gov (United States)

    Ye, Cang; Borenstein, Johann

    2004-09-01

    In order to maneuver autonomously on rough terrain, a mobile robot must constantly decide whether to traverse or circumnavigate terrain features ahead. This ability is called Obstacle Negotiation (ON). A critical aspect of ON is the so-called traversability analysis, which evaluates the level of difficulty associated with the traversal of the terrain. This paper presents a new method for traversability analysis, called T-transformation. It is implemented in a local terrain map as follows: (1) For each cell in the local terrain map, a square terrain patch is defined that symmetrically overlays the cell; (2) a plane is fitted to the data points in the terrain patch using a least-square approach and the slope of the least-squares plane and the residual of the fit are computed and used to calculate the Traversability Index (TI) for that cell; (3) after each cell is assigned a TI value, the local terrain map is transformed into a traversability map. The traversability map is further transformed into a traversability field histogram where each element represents the overall level of difficulty to move along the corresponding direction. Based on the traversability field histogram our reactive ON system then computes the steering and velocity commands to move the robot toward the intended goal while avoiding areas of poor traversability. The traversability analysis algorithm and the overall ON system were verified by extensive simulation. We verified our method partially through experiments on a Segway Robotics Mobility Platform (RMP), albeit only on flat terrain.

  8. Sexual differences in prevalence of a new species of trypanosome infecting túngara frogs

    Directory of Open Access Journals (Sweden)

    Ximena E. Bernal

    2016-04-01

    Full Text Available Trypanosomes are a diverse group of protozoan parasites of vertebrates transmitted by a variety of hematophagous invertebrate vectors. Anuran trypanosomes and their vectors have received relatively little attention even though these parasites have been reported from frog and toad species worldwide. Blood samples collected from túngara frogs (Engystomops pustulosus, a Neotropical anuran species heavily preyed upon by eavesdropping frog-biting midges (Corethrella spp., were examined for trypanosomes. Our results revealed sexual differences in trypanosome prevalence with female frogs being rarely infected (<1%. This finding suggests this protozoan parasite may be transmitted by frog-biting midges that find their host using the mating calls produced by male frogs. Following previous anuran trypanosome studies, we examined 18S ribosomal RNA gene to characterize and establish the phylogenetic relationship of the trypanosome species found in túngara frogs. A new species of giant trypanosome, Trypanosoma tungarae n. sp., is described in this study. Overall the morphometric data revealed that the trypomastigotes of T. tungarae n. sp. are similar to other giant trypanosomes such as Trypanosoma rotatorium and Trypanosoma ranarum. Despite its slender and long cell shape, however, 18S rRNA gene sequences revealed that T. tungarae n. sp. is sister to the rounded-bodied giant trypanosome, Trypanosoma chattoni. Therefore, morphological convergence explains similar morphology among members of two non-closely related groups of trypanosomes infecting frogs. The results from this study underscore the value of coupling morphological identification with molecular characterization of anuran trypanosomes.

  9. Anti-trypanosomal Potential of Eucalyptus Camaldulensis

    Directory of Open Access Journals (Sweden)

    Y.A. Kabiru

    2013-04-01

    Full Text Available Chemotherapy of African trypanosomiasis in both the human and animal forms has been confronted with multidimensional problems that include paucity of drugs, resistance, high cost, prolonged treatment protocol and adverse side effects. The main objective of this study was to explore alternative sources of antitrypanosomal agents from the leaves, stem and root barks of Eucalyptus camaldulensis The plant parts were sequentially extracted with hexane, ethyl acetate, methanol and water; and the extracts screened for antitrypanosomal activity. Mice infected with Trypanosoma brucei brucei were administered intraperitoneally doses ranging from 200-600 mg/kg body weight/day of the extracts for 21 consecutive days. One control group was treated with 3.5mg/kg bodyweight of berenil while the other control group was left untreated. The methanol extract of E. camaldulensis (leaf produced complete cure for the animals in the different dose groups and survived as long as those treated with the standard drug, berenil, although the clearance time was faster for the standard drug. Sub inoculation of healthy mice with the blood and Cerebrospinal Fluid (CSF of the cured mice did not result in infection, thus indicating a complete and permanent cure. Acute toxicity studies of the methanol extract of E. camaldulensis (leaf confirmed the safety of the extract because no mortality was recorded even at 5000 mg/kg bodyweight. However, the extract had no prophylactic activity. Bioassay-guided fractionation of the crude methanol extract of E. camaldulensis leaf gave 10 fractions, with only fractions 8 and 9 exhibiting minimal antitrypanosomal activities that were not comparable to those of the crude extract and the standard drug (p≤0.05. Phytochemical screening revealed the presence of terpenes, steroids, saponins, tannins, alkaloids and fatty acids in both the crude extract and fraction 9; while fraction 8 contained only terpenes, steroids and fatty acids. Data from GC

  10. The molecular basis of livestock diseases in developing countries as illustrated by African trypanosomosis

    International Nuclear Information System (INIS)

    Full text: Viral, bacterial, protozoan and helminthic diseases of domestic livestock continue to be serious impediments to the agricultural economies of most developing countries. Many of these livestock pathogens have evolved sophisticated molecular mechanisms for evading or circumventing the mammalian immune system. These same pathogens frequently acquire resistance to drugs that are initially effective. African trypanosomes are protozoan parasites that cause the fatal diseases of ngana in cattle, surra in camels and horses and sleeping sickness in humans. They are the paradigm for a livestock pathogen in developing countries for which much is now known, yet little has been achieved in controlling or eliminating the disease. African trypanosomes were identified as the cause of trypanosomosis more than 100 years ago and in many ways are ideal pathogens to study in the laboratory. From the perspective of research on the parasites themselves, excellent laboratory rodent models for their infection exist. They can be readily grown in vitro in culture flasks. Their mechanism of immune evasion is known. The completed DNA sequence of their genome is nearly determined. They can be manipulated genetically in the laboratory - genes can be mutated and deleted from, or inserted into, their genome. They contain unique organelles and metabolic pathways not found in mammals that could potentially be exploited for new drug development. They are pathogens of humans as well as livestock, so they attract the interests and enormous resources of the medical research community. Advantages also exist from the standpoint of experiments on their animal hosts. Breeds of domestic cattle that are either 'trypanotolerant' or trypanosome-sensitive are well known and animals of each type have been cross-bred. The molecular basis of trypanosome-tolerance in at least one indigenous wild animal species (the Cape buffalo) has been elucidated. The reason some African trypanosome species are killed

  11. Adult blood-feeding tsetse flies, trypanosomes, microbiota and the fluctuating environment in sub-Saharan Africa.

    Science.gov (United States)

    Geiger, Anne; Ponton, Fleur; Simo, Gustave

    2015-07-01

    The tsetse fly vector transmits the protozoan Trypanosoma brucei, responsible for Human African Trypanosomiasis, one of the most neglected tropical diseases. Despite a recent decline in new cases, it is still crucial to develop alternative strategies to combat this disease. Here, we review the literature on the factors that influence trypanosome transmission from the fly vector to its vertebrate host (particularly humans). These factors include climate change effects to pathogen and vector development (in particular climate warming), as well as the distribution of host reservoirs. Finally, we present reports on the relationships between insect vector nutrition, immune function, microbiota and infection, to demonstrate how continuing research on the evolving ecology of these complex systems will help improve control strategies. In the future, such studies will be of increasing importance to understand how vector-borne diseases are spread in a changing world. PMID:25500509

  12. Application of field methods to assess isometamidium resistance of trypanosomes in cattle in western Ethiopia

    DEFF Research Database (Denmark)

    Tewelde, N.; Abebe, G.; Eisler, M.;

    2004-01-01

    This study assessed the degree of isometamidium resistance of trypanosomes infecting cattle in the upper Didessa valley of western Ethiopia. An initial prevalence study was conducted to identify sites with a high risk of trypanosmosis in cattle. The trypanosome prevalence varied widely, with two...

  13. Inositol phosphate pathway controls transcription of telomeric expression sites in trypanosomes.

    Science.gov (United States)

    Cestari, Igor; Stuart, Ken

    2015-05-26

    African trypanosomes evade clearance by host antibodies by periodically changing their variant surface glycoprotein (VSG) coat. They transcribe only one VSG gene at a time from 1 of about 20 telomeric expression sites (ESs). They undergo antigenic variation by switching transcription between telomeric ESs or by recombination of the VSG gene expressed. We show that the inositol phosphate (IP) pathway controls transcription of telomeric ESs and VSG antigenic switching in Trypanosoma brucei. Conditional knockdown of phosphatidylinositol 5-kinase (TbPIP5K) or phosphatidylinositol 5-phosphatase (TbPIP5Pase) or overexpression of phospholipase C (TbPLC) derepresses numerous silent ESs in T. brucei bloodstream forms. The derepression is specific to telomeric ESs, and it coincides with an increase in the number of colocalizing telomeric and RNA polymerase I foci in the nucleus. Monoallelic VSG transcription resumes after reexpression of TbPIP5K; however, most of the resultant cells switched the VSG gene expressed. TbPIP5K, TbPLC, their substrates, and products localize to the plasma membrane, whereas TbPIP5Pase localizes to the nucleus proximal to telomeres. TbPIP5Pase associates with repressor/activator protein 1 (TbRAP1), and their telomeric silencing function is altered by TbPIP5K knockdown. These results show that specific steps in the IP pathway control ES transcription and antigenic switching in T. brucei by epigenetic regulation of telomere silencing. PMID:25964327

  14. Traversable asymptotically flat wormholes in Rastall gravity

    CERN Document Server

    Moradpour, H

    2016-01-01

    Having introduced the Rastall gravitational theory, and by virtue of the fact that this theory has two unknown parameters, we take the Newtonian limit to define a new parameter for Rastall gravitational theory; a useful dimensionless parameter for simplifying calculations in the Rastall framework. Equipped with basics of the theory, we study the properties of traversable asymptotically flat wormholes in Rastall framework. Then, we investigate the possibility of supporting such geometries by a source with the same state parameter as that of the baryonic matters. Our survey indicates that the parameters of Rastall theory affect the wormhole parameters. It also shows the weak energy condition is violated for all of the studied cases. We then come to investigate the possibility of supporting such geometries by a source of negative energy density and the same state parameter as that of dark energy. Such dark energy-like sources have positive radial and transverse pressures.

  15. Gravitinos Tunneling From Traversable Lorentzian Wormholes

    CERN Document Server

    Sakalli, I

    2015-01-01

    Recent research shows that Hawking radiation (HR) is also possible around the trapping horizon of a wormhole. In this article, we show that the HR of gravitino (spin-$3/2$) particles from the traversable Lorentzian wormholes (TLWH) reveals a negative Hawking temperature (HT). We first introduce the TLWH in the past outer trapping horizon geometry (POTHG). Next, we derive the Rarita-Schwinger equations (RSEs) for that geometry. Then, using both the Hamilton-Jacobi (HJ) ans\\"{a}tz and the WKB approximation in the quantum tunneling method, we obtain the probabilities of the emission/absorption modes. Finally, we derive the tunneling rate of the emitted gravitino particles, and succeed to read the HT of the TLWH.

  16. Gravitinos tunneling from traversable Lorentzian wormholes

    Science.gov (United States)

    Sakalli, I.; Ovgun, A.

    2015-09-01

    Recent research shows that Hawking radiation (HR) is also possible around the trapping horizon of a wormhole. In this article, we show that the HR of gravitino (spin-) particles from the traversable Lorentzian wormholes (TLWH) reveals a negative Hawking temperature (HT). We first introduce the TLWH in the past outer trapping horizon geometry (POTHG). Next, we derive the Rarita-Schwinger equations (RSEs) for that geometry. Then, using both the Hamilton-Jacobi (HJ) ansätz and the WKB approximation in the quantum tunneling method, we obtain the probabilities of the emission/absorption modes. Finally, we derive the tunneling rate of the emitted gravitino particles, and succeed to read the HT of the TLWH.

  17. Dissipation and traversal time in Josephson junctions

    International Nuclear Information System (INIS)

    The various ways of evaluating dissipative effects in macroscopic quantum tunneling are re-examined. The results obtained by using functional integration, while confirming those of previously given treatments, enable a comparison with available experimental results relative to Josephson junctions. A criterion based on the shortening of the semiclassical traversal time τ of the barrier with regard to dissipation can be established, according to which Δτ/τ > or approx. N/Q, where Q is the quality factor of the junction and N is a numerical constant of order unity. The best agreement with the experiments is obtained for N=1.11, as it results from a semiempirical analysis based on an increase in the potential barrier caused by dissipative effects.

  18. The LPM showers traversing the atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Wada, Y [Graduated School of Science and Engineering, Saitama University, Saitama (Japan); Kato, M [Kyowa Interface Science Co., Ltd., Saitama (Japan); Inoue, N [Department of Physics, Saitama University, Saitama (Japan); Misaki, A [Advanced Research Institute for Science and Engineering, Waseda University, Tokyo (Japan)

    2006-05-15

    We simulate the LPM showers due to Extremely-High-Energy(EHE) neutrinos traversing atmosphere horizontally without colliding with the Earth. We calculate the LPM showers with energies of 10{sup 17}eV to 10{sup 22}eV, using the hybrid method as exactly as possible. Reffecting the complicated change in the air density along the trajectories of the shower developments, the variety of the LPM showers is shown to depend on their starting points and their heights. The EHE LPM showers in atmosphere are exclusively produced by EHE neutrinos. Therefore, the studies on the LPM showers are very important for EHE neutrino astrophysics. As an example, the air fluorescence photon profiles of the LPM showers are also given for the future satellite-based experiment.

  19. van Vleck determinants: traversable wormhole spacetimes

    CERN Document Server

    Visser, Matt

    2009-01-01

    Calculating the van Vleck determinant in traversable wormhole spacetimes is an important ingredient in understanding the physical basis behind Hawking's chronology protection conjecture. This paper presents extensive computations of this object --- at least in the short--throat flat--space approximation. An important technical trick is to use an extension of the usual junction condition formalism to probe the full Riemann tensor associated with a thin shell of matter. Implications with regard to Hawking's chronology protection conjecture are discussed. Indeed, any attempt to transform a single isolated wormhole into a time machine results in large vacuum polarization effects sufficient to disrupt the internal structure of the wormhole before the onset of Planck scale physics, and before the onset of time travel. On the other hand, it is possible to set up a putative time machine built out of two or more wormholes, each of which taken in isolation is not itself a time machine. Such ``Roman configurations'' are...

  20. Trypanosomiasis in Red Sokoto and West African Dwarf Goats at Ikpa Abattoir, Nsukka, Enugu State, Nigeria

    Directory of Open Access Journals (Sweden)

    Okafor Obioma Juliet

    2013-10-01

    Full Text Available Goat serves as a major investment to most homes in Nigeria, mainly for provision of animal protein and income. The output of this animal is disturbed by Tsetse infestation which is the primary vector of Trypanosome. A survey of Trypanosomiasis of goat in Ikpa abattoir Nsukka, Enugu State, Nigeria was carried out between September and October 2010. This was aimed at determining the species of Trypanosome prevalent in the area and their infection rates among breeds of goat. 106 goats were sampled, among which 15(14.1% were positive for Trypanosome infection. The infection rates among the goat breeds were; Sokoto red (10.4% and West African Dwarf Goat (50.0%. The species of Trypanosome encountered were Trypanosoma vivax(66.7% and Trypanosoma brucei (33.3%. In the infection by sex, this was common among female goats in the various breeds examined and this stood as follows; 9.4% in Sokoto red and 4.7% in West African Dwarf goat. Considering the overall infection rate of Trypanosome in the breeds of goat in the study area, this was relatively high when compared with similar results in related areas; chemo prophylactic and insect control measures should be put in place to rescue the area.

  1. An Integrated Traverse Planner and Analysis Tool for Planetary Exploration

    OpenAIRE

    Johnson, Aaron William; Hoffman, Jeffrey A.; Newman, Dava; Mazarico, Erwan Matias; Zuber, Maria

    2010-01-01

    Future planetary explorations will require surface traverses of unprecedented frequency, length, and duration. As a result, there is need for exploration support tools to maximize productivity, scientific return, and safety. The Massachusetts Institute of Technology is currently developing such a system, called the Surface Exploration Traverse Analysis and Navigation Tool (SEXTANT). The goal of this system is twofold: to allow for realistic simulations of traverses in order to assist with har...

  2. P-CSCF's Algorithm for Solving NAT Traversal

    Science.gov (United States)

    Kim, Jung-Ho; Cho, Jae-Hyoung; Lee, Jae-Oh

    Many ways for efficient use of limited IP address of IPv4 are existed. The one of these ways is to construct the private network using Network Address Translator (NAT). NAT filtering rule makes network management easier. However, NAT Filtering rule makes NAT Traversal. Many solutions like Simple Traversal of UDP through NAT (STUN), Traversal Using Relay NAT (TURN) and Media Relay method exist. But these solutions require additional servers or devices. So, we suggest that P-CSCFs in the IP Multimedia Subsystem (IMS) change the packet's header and solve the NAT Traversal without any additional equipment.

  3. Trypanosome infections in warthogs (Phacochoerus aethiopicus) in the Gambia.

    Science.gov (United States)

    Claxton, J R; Faye, J A; Rawlings, P

    1992-03-01

    The prevalence of trypanosome infections in warthogs (Phacochoerus aethiopicus) in The Gambia was found to be 11% of a sample of 62 animals. All isolates were identified as Trypanosoma simiae. Serological evidence indicated a higher level of exposure to T. simiae, but results were inconclusive for the presence of Trypanosoma congolense. The course of T. simiae infection in warthog piglets showed a rapidly rising parasitaemia, with a concomitant fall in packed cell volume, and resulted in a prolonged period of low-level parasitaemia. The same infections killed domestic piglets. PMID:1502780

  4. Synthesis and evaluation of analogs of the phenylpyridazinone NPD-001 as potent trypanosomal TbrPDEB1 phosphodiesterase inhibitors and in vitro trypanocidals.

    Science.gov (United States)

    Veerman, Johan; van den Bergh, Toine; Orrling, Kristina M; Jansen, Chimed; Cos, Paul; Maes, Louis; Chatelain, Eric; Ioset, Jean-Robert; Edink, Ewald E; Tenor, Hermann; Seebeck, Thomas; de Esch, Iwan; Leurs, Rob; Sterk, Geert Jan

    2016-04-01

    Trypanosomal phosphodiesterases B1 and B2 (TbrPDEB1 and TbrPDEB2) play an important role in the life cycle of Trypanosoma brucei, the causative parasite of human African trypanosomiasis (HAT), also known as African sleeping sickness. Knock down of both enzymes leads to cell cycle arrest and is lethal to the parasite. Recently, we reported the phenylpyridazinone, NPD-001, with low nanomolar IC50 values on both TbrPDEB1 (IC50: 4nM) and TbrPDEB2 (IC50: 3nM) (J. Infect. Dis.2012, 206, 229). In this study, we now report on the first structure activity relationships of a series of phenylpyridazinone analogs as TbrPDEB1 inhibitors. A selection of compounds was also shown to be anti-parasitic. Importantly, a good correlation between TbrPDEB1 IC50 and EC50 against the whole parasite was observed. Preliminary analysis of the SAR of selected compounds on TbrPDEB1 and human PDEs shows large differences which shows the potential for obtaining parasite selective PDE inhibitors. The results of these studies support the pharmacological validation of the Trypanosome PDEB family as novel therapeutic approach for HAT and provide as well valuable information for the design of potent TbrPDEB1 inhibitors that could be used for the treatment of this disease. PMID:26935942

  5. Lectins discriminate between pathogenic and nonpathogenic South American trypanosomes

    Energy Technology Data Exchange (ETDEWEB)

    de Miranda Santos, I.K.; Pereira, M.E.

    1984-09-01

    Cell surface carbohydrates of Trypanosoma cruzi, Trypanosoma rangeli, and Trypanosoma conorhini were analyzed by a micro-agglutination assay employing 27 highly purified lectins and by binding assays using various /sup 125/I-labeled lectins. The following seven lectins discriminated between the trypanosomes: 1) tomato lectin (an N-acetyl-D-glucosamine-binding protein), both in purified form and as crude tomato juice; 2) Bauhinea purpurea and Sophora japonica lectins (both N-acetyl-D-galactosamine-binding proteins), which selectively agglutinated T. cruzi; 3) Vicia villosa (an N-acetyl-D-galactosamine-binding protein) which was specific for T. rangeli; 4) peanut lectin (a D-galactose-binding protein) both in purified form and as crude saline extract; and 5) Ulex europaeus and Lotus tetragonolobus (both L-fucose-binding proteins) lectins which reacted only with T. conorhini. Binding studies with 125I-labeled lectins were performed to find whether unagglutinated cells of the three different species of trypanosomes might have receptors for these lectins, in which case absence of agglutination could be due to a peculiar arrangement of the receptors. These assays essentially confirmed the agglutination experiments.

  6. Lectins discriminate between pathogenic and nonpathogenic South American trypanosomes

    International Nuclear Information System (INIS)

    Cell surface carbohydrates of Trypanosoma cruzi, Trypanosoma rangeli, and Trypanosoma conorhini were analyzed by a micro-agglutination assay employing 27 highly purified lectins and by binding assays using various 125I-labeled lectins. The following seven lectins discriminated between the trypanosomes: 1) tomato lectin (an N-acetyl-D-glucosamine-binding protein), both in purified form and as crude tomato juice; 2) Bauhinea purpurea and Sophora japonica lectins (both N-acetyl-D-galactosamine-binding proteins), which selectively agglutinated T. cruzi; 3) Vicia villosa (an N-acetyl-D-galactosamine-binding protein) which was specific for T. rangeli; 4) peanut lectin (a D-galactose-binding protein) both in purified form and as crude saline extract; and 5) Ulex europaeus and Lotus tetragonolobus (both L-fucose-binding proteins) lectins which reacted only with T. conorhini. Binding studies with 125I-labeled lectins were performed to find whether unagglutinated cells of the three different species of trypanosomes might have receptors for these lectins, in which case absence of agglutination could be due to a peculiar arrangement of the receptors. These assays essentially confirmed the agglutination experiments

  7. Excreted/Secreted Proteins from Trypanosome Procyclic Strains

    Directory of Open Access Journals (Sweden)

    Celestine Michelle Atyame Nten

    2010-01-01

    Full Text Available Trypanosoma secretome was shown to be involved in parasite virulence and is suspected of interfering in parasite life-cycle steps such as establishment in the Glossina midgut, metacyclogenesis. Therefore, we attempted to identify the proteins secreted by procyclic strains of T. brucei gambiense and T. brucei brucei, responsible for human and animal trypanosomiasis, respectively. Using mass spectrometry, 427 and 483 nonredundant proteins were characterized in T. brucei brucei and T. brucei gambiense secretomes, respectively; 35% and 42% of the corresponding secretome proteins were specifically secreted by T. brucei brucei and T. brucei gambiense, respectively, while 279 proteins were common to both subspecies. The proteins were assigned to 12 functional classes. Special attention was paid to the most abundant proteases (14 families because of their potential implication in the infection process and nutrient supply. The presence of proteins usually secreted via an exosome pathway suggests that this type of process is involved in trypanosome ESP secretion. The overall results provide leads for further research to develop novel tools for blocking trypanosome transmission.

  8. Programming errors in traversal programs over structured data

    CERN Document Server

    Laemmel, Ralf; Kaiser, Markus

    2012-01-01

    Traversal strategies \\'a la Stratego (also \\'a la Strafunski and 'Scrap Your Boilerplate') provide an exceptionally versatile and uniform means of querying and transforming deeply nested and heterogeneously structured data including terms in functional programming and rewriting, objects in OO programming, and XML documents in XML programming. However, the resulting traversal programs are prone to programming errors. We are specifically concerned with errors that go beyond conservative type errors; examples we examine include divergent traversals, prematurely terminated traversals, and traversals with dead code. Based on an inventory of possible programming errors we explore options of static typing and static analysis so that some categories of errors can be avoided. This exploration generates suggestions for improvements to strategy libraries as well as their underlying programming languages. Haskell is used for illustrations and specifications with sufficient explanations to make the presentation comprehens...

  9. Update History of This Database - Trypanosomes Database | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available [ Credits ] BLAST Search Image Search Home About Archive Update History Contact us Trypanosomes Database... Update History of This Database Date Update contents 2014/05/07 The contact informatio...n is corrected. The features and manner of utilization of the database are corrected. 2014/02/04 Trypanosomes Database... English archive site is opened. 2011/04/04 Trypanosomes Database ( htt...p://www.tanpaku.org/tdb/ ) is opened. Joomla SEF URLs by Artio About This Database Database Description Down

  10. Mars Rover Curiosity Traverses of Sand Ripples

    Science.gov (United States)

    Stein, N.; Arvidson, R. E.; Zhou, F.; Heverly, M.; Maimone, M.; Hartman, F.; Bellutta, P.; Iagnemma, K.; Senatore, C.

    2014-12-01

    Martian sand ripples present a challenge for rover mobility, with drives over ripples often characterized by high wheel sinkage and slippage that can lead to incipient embedding. Since landing in Gale Crater, Curiosity has traversed multiple sand ripples, including the transverse aeolian ridge (TAR) straddling Dingo Gap on sols 533 and 535. On sol 672, Curiosity crossed backward over a series of sand ripples before ending its drive after high motor currents initiated visual odometry (VO) processing, which detected 77% slip, well in excess of the imposed 60% slip limit. At the end of the drive, the right front wheel was deeply embedded at the base of a ripple flank with >20 cm sinkage and the rear wheels were near a ripple crest. As Curiosity continues its approach to Mount Sharp it will have to cross multiple ripples, and thus it is important to understand Curiosity's performance on sol 672 and over similar ripples. To this end the sol 672 drive was simulated in ARTEMIS (Adams-Based Rover Terramechanics Interaction Simulator), a software tool consisting of realistic rover mechanical models, a wheel-terrain interaction module for deformable and non-deformable surfaces, and realistic terrain models. ARTEMIS results, Dumont Dunes tests performed in the Mojave Desert using the Scarecrow test rover, and single wheel tests performed at MIT indicate that the high slip encountered on sol 672 likely occurred due to a combination of rover attack angle, ripple geometry, and soil properties. When ripple wavelength approaches vehicle length, the rover can reach orientations in which the leading wheels carry minimal normal loads and the trailing wheels sink deeply, resulting in high slippage and insufficient thrust to propel the rover over ripples. Even on relatively benign (i.e. low tilt) terrains, local morphology can impose high sinkage, thus impeding rover motion. Work is underway to quantify Curiosity's drive performance over various ripple geometries to retrieve soil

  11. Ag-ELISA for the detection of trypanosome infections in cattle and camels

    International Nuclear Information System (INIS)

    This document describes very briefly the two elisa kits used for the detection of trypanosome infections in cattle and camels. Results on the specificity and sensitivity of assays performed with the kits are summarized. 9 refs

  12. Spatial distribution of African Animal Trypanosomiasis in Suba and Teso districts in Western Kenya

    Directory of Open Access Journals (Sweden)

    Jung'a Joseph O

    2010-01-01

    Full Text Available Abstract Background Studies on the epidemiology of African Animal Trypanosomiasis (AAT rarely consider the spatial dimension of disease prevalence. This problem is confounded by use of parasitological diagnostic methods of low sensitivity in field surveys. Here we report a study combining highly sensitive and species specific molecular diagnostic methods, and Geographical information system (GIS for spatial analysis of trypanosome infection patterns, to better understand its epidemiology. Blood samples from 44 and 59 animals randomly selected from Teso and Suba districts respectively were screened for trypanosomes using PCR diagnostic assays. Spatial distribution of the positive cases was mapped and average nearest neighbour analysis used to determine the spatial pattern of trypanosome cases detected. Findings Trypanosome prevalence of 41% and 29% in Suba and Teso districts respectively was observed. T. vivax infections were most prevalent in both areas. Higher proportions of T. brucei infections (12% were observed in Suba, a known sleeping sickness foci compared with 2% in Teso. Average nearest neighbour analysis showed the pattern of trypanosome infections as random. An overlay with tsetse maps showed cases lying outside the tsetse infested areas, mostly being cases of T. vivax which is known to be transmitted both biologically by tsetse and mechanically by biting flies. Conclusion These findings suggest a need to design control strategies that target not just the biological vector tsetse, but also the parasite in cattle in order to clear the possibly mechanically transmitted T. vivax infections. There is need to also review the accuracy of available tsetse maps.

  13. Machine learning challenges in Mars rover traverse science

    Science.gov (United States)

    Castano, R.; Judd, M.; Anderson, R. C.; Estlin, T.

    2003-01-01

    The successful implementation of machine learning in autonomous rover traverse science requires addressing challenges that range from the analytical technical realm, to the fuzzy, philosophical domain of entrenched belief systems within scientists and mission managers.

  14. Geometric structure of the generic static traversable wormhole throat

    OpenAIRE

    Hochberg, David; Visser, Matt

    1997-01-01

    Traversable wormholes have traditionally been viewed as intrinsically topological entities in some multiply connected spacetime. Here, we show that topology is too limited a tool to accurately characterize a generic traversable wormhole: in general one needs geometric information to detect the presence of a wormhole, or more precisely to locate the wormhole throat. For an arbitrary static spacetime we shall define the wormhole throat in terms of a 2-dimensional constant-time hypersurface of m...

  15. Insect antimicrobial peptides act synergistically to inhibit a trypanosome parasite.

    Science.gov (United States)

    Marxer, Monika; Vollenweider, Vera; Schmid-Hempel, Paul

    2016-05-26

    The innate immune system provides protection from infection by producing essential effector molecules, such as antimicrobial peptides (AMPs) that possess broad-spectrum activity. This is also the case for bumblebees, Bombus terrestris, when infected by the trypanosome, Crithidia bombi Furthermore, the expressed mixture of AMPs varies with host genetic background and infecting parasite strain (genotype). Here, we used the fact that clones of C. bombi can be cultivated and kept as strains in medium to test the effect of various combinations of AMPs on the growth rate of the parasite. In particular, we used pairwise combinations and a range of physiological concentrations of three AMPs, namely Abaecin, Defensin and Hymenoptaecin, synthetized from the respective genomic sequences. We found that these AMPs indeed suppress the growth of eight different strains of C. bombi, and that combinations of AMPs were typically more effective than the use of a single AMP alone. Furthermore, the most effective combinations were rarely those consisting of maximum concentrations. In addition, the AMP combination treatments revealed parasite strain specificity, such that strains varied in their sensitivity towards the same mixtures. Hence, variable expression of AMPs could be an alternative strategy to combat highly variable infections.This article is part of the themed issue 'Evolutionary ecology of arthropod antimicrobial peptides'. PMID:27160603

  16. Presence of trypanosome species and anemic status of dogs in Zuru, Nigeria

    Directory of Open Access Journals (Sweden)

    Rafi Rabecca Tono

    2015-10-01

    Full Text Available The aim of this research is to study the presence and prevalence of trypanosome species in local dogs between January and July, 2010 in the Zuru area of Kebbi State, Nigeria.Standard trypanosome detection methods comprising of wet blood films, thin films and microhaematocrit centrifugation technique were used to detect trypanosomes; while the degree of anemia was determined through the use of FAMACHA® eye colour chart and packed cell volume values. A total of 567 dogs were enumerated in fourteen locations within the study area out of which 192 (33.7% were randomly examined and 4 (2.08% were positive for the presence of trypanosomes. All positive samples morphologically belong to the Trypanosoma brucei group. The obtained PCV values showed that 50 (26.04% dogs were anemic, while the FAMACHA® detected anemia status of varying degrees in 104 (77% sampled dogs.These findings are significant as this is the first time that the trypanosome infection will be reported in dogs from the study area. This study establishes the presence of Trypanosoma brucei group in the study area, which is of zoonotic and economic importance.

  17. Geometric structure of the generic static traversable wormhole throat

    CERN Document Server

    Hochberg, D; Hochberg, David; Visser, Matt

    1997-01-01

    Traversable wormholes have traditionally been viewed as intrinsically topological entities in some multiply connected spacetime. Here, we show that topology is too limited a tool to accurately characterize a generic traversable wormhole: in general one needs geometric information to detect the presence of a wormhole, or more precisely to locate the wormhole throat. For an arbitrary static spacetime we shall define the wormhole throat in terms of a 2--dimensional constant-time hypersurface of minimal area. (Zero trace for the extrinsic curvature plus a ``flare--out'' condition.) This enables us to severely constrain the geometry of spacetime at the wormhole throat and to derive generalized theorems regarding violations of the energy conditions---theorems that do not involve geodesic averaging but nevertheless apply to situations much more general than the spherically symmetric Morris--Thorne traversable wormhole. [For example: the null energy condition (NEC), when suitably weighted and integrated over the worm...

  18. Geometric dark energy traversable wormholes constrained by astrophysical observations

    CERN Document Server

    Wang, Deng

    2016-01-01

    In this letter, we introduce the astrophysical observations into the wormhole research, which is not meant to general parameters constraints for the dark energy models, in order to understand more about in which stage of the universe evolutions wormholes may exist through the investigation of the evolution behavior of the cosmic equation of state parameter. As a concrete instance, we investigate the Ricci dark energy (RDE) traversable wormholes constrained by astrophysical data-sets. Particularly, we can discover from Fig. \\ref{fig5} of the present work, when the effective equation of state parameter $\\omega_X<-1$, namely, the Null Energy conditions (NEC) is violated clearly, the wormholes will appear (open). Subsequently, six specific solutions of static and spherically symmetric traversable wormhole supported by the RDE are obtained. Except for the case of constant redshift function, in which the solution is not only asymptotically flat but also traversable, the remaining five solutions are all not asymp...

  19. Post eclosion age predicts the prevalence of midgut trypanosome infections in Glossina.

    Directory of Open Access Journals (Sweden)

    Deirdre P Walshe

    Full Text Available The teneral phenomenon, as observed in Glossina sp., refers to the increased susceptibility of the fly to trypanosome infection when the first bloodmeal taken is trypanosome-infected. In recent years, the term teneral has gradually become synonymous with unfed, and thus fails to consider the age of the newly emerged fly at the time the first bloodmeal is taken. Furthermore, conflicting evidence exists of the effect of the age of the teneral fly post eclosion when it is given the infected first bloodmeal in determining the infection prevalence. This study demonstrates that it is not the feeding history of the fly but rather the age (hours after eclosion of the fly from the puparium of the fly when it takes the first (infective bloodmeal that determines the level of fly susceptibility to trypanosome infection. We examine this phenomenon in male and female flies from two distinct tsetse clades (Glossina morsitans morsitans and Glossina palpalis palpalis infected with two salivarian trypanosome species, Trypanosoma (Trypanozoon brucei brucei and Trypanosoma (Nannomonas congolense using Fisher's exact test to examine differences in infection rates. Teneral tsetse aged less than 24 hours post-eclosion (h.p.e. are twice as susceptible to trypanosome infection as flies aged 48 h.p.e. This trend is conserved across sex, vector clade and parasite species. The life cycle stage of the parasite fed to the fly (mammalian versus insect form trypanosomes does not alter this age-related bias in infection. Reducing the numbers of parasites fed to 48 h.p.e., but not to 24 h.p.e. flies, increases teneral refractoriness. The importance of this phenomenon in disease biology in the field as well as the necessity of employing flies of consistent age in laboratory-based infection studies is discussed.

  20. Distribution of lipophosphoglycan-associated epitopes in different Leishmania species and in African trypanosomes.

    Science.gov (United States)

    Tolson, D L; Schnur, L F; Jardim, A; Pearson, T W

    1994-01-01

    Monoclonal antibody (mAb) CA7AE binds specifically to the phosphorylated Gal-beta 1,4-Man disaccharide repeat epitope of Leishmania donovani lipophosphoglycan (LPG). This mAb detected the repeat epitope in most but not all of a wide variety of Leishmania species and strains examined. MAb CA7AE also bound to both glycoprotein and carbohydrate antigens in medium from L. donovani promastigote cultures. Specifically, mAb CA7AE bound the delipidated form of LPG, the phosphoglycan, and a glycoprotein both of which are released into the medium by the parasite indicating that both share a specific phosphorylated carbohydrate epitope. The epitope was detected in sera from L. donovani-infected (kala-azar positive) patients when mAb CA7AE was used in an antigen-capture enzyme-linked immunosorbent assay (ELISA). MAb L157 is specific for a protein that is found associated with L. donovani LPG, the lipophosphoglycan-associated protein (LPGAP). This mAb bound to molecules in all 19 strains (representing 9 species) of Leishmania promastigotes and to molecules in 2 species of Trypanosoma procyclic culture forms. This wide distribution of the LPGAP epitope implies that it may have a conserved function, for example, in the biochemistry or arrangement of parasite surface molecules. In addition, since the LPGAP is involved in the stimulation of T lymphocyte proliferation, its wide distribution amongst different Leishmania species suggests that it may be an ideal molecule for testing as a vaccine for leishmaniasis. PMID:7528916

  1. Transient field for W ions traversing Fe hosts and for Os ions traversing Fe and Ni hosts

    International Nuclear Information System (INIS)

    Transient field strengths were measured for 184W and 186W ions traversing thin, magnetized Fe foils with velocities in the range 1.8 ≤ v/v>=o ≤ 5.7 (v>=o Bohr velocity) and for 188Os, 190Os, 192Os ions traversing polarized Ni hosts with average velocities =o> ∼ 4. The present measured transient field strengths, together with previously measured results for W, Os ions, are compared with transient-field strength parametrizations, and discussed in terms of microscopic models of the transient field

  2. Drug uptake (DAPI) of trypanosomes (T. brucei) and antitrypanosomal activity in vitro, in culture and in vivo studied by microscope fluorometry, chromatogram spectrophotometry and radiotracer techniques

    International Nuclear Information System (INIS)

    The present study had the following objectives: 1) Investigation of the specific binding and location of the diamidine DAPI within trypanosomes by fluorescence microscopy. 2) Development and standardization of a microscope fluorometry technique for measuring DAPI uptake of single trypanosomes. 3) Determination of the effect of incubation media, exposure time, and drug concentration on DAPI uptake of single trypanosomes. 4) Development of a technique applicable for quantitative fluorescence chemical analysis of DAPI uptake of trypanosomes. 5) Determination of drug uptake of trypanosomes using 14C labelled DAPI. 6) Comparison of the values obtained by the three methods. (orig./MG)

  3. Effects of pathogenic trypanosomes on the mammalian reproductive system

    International Nuclear Information System (INIS)

    The aim of the present investigation was to study the pathogenic effects of infection with Trypanosoma congolense on the ruminant reproductive system with particular emphasis on the hormonal control of oestrus. In particular, the effects of infection were monitored with specific regard to the reproduction of plasma progesterone and the sexual behaviour of the animals. Initially, experiments were carried out using goats infected by the bites of Glossina morsitans carrying T. congolense. Control, uninfected but drug-treated goats showed regular oestrous cycles during the experiments, with cycle lengths of between 19 and 23 days. In contrast, in the infected goats, three out of four animals did not show regular oestrous cycles. The periods without oestrus activity varied between 53 and 97 days. Determination of plasma progesterone levels suggested that in these animals the luteal phase of oestrus was prolonged, indicating a persistent corpus luteum. In further experiments using Boran cattle, a group of 22 animals were selected, 12 of which were infected with T. congolense IL1180. The packed cell volume in infected cattle fell to <20% and most of the animals showed loss in body weight. Two animals died and of the remainder five were treated with trypanocidal drug 60 days after infection and five 90 days after infection. In the remaining ten infected cows, nine stopped cyclical activity: in five there was a prolonged luteal phase with elevated progesterone levels and in the remainder progesterone levels fell to basal values for up to 100 days. After treatment these infected cows resumed cyclical activity and within three or four cycles were cycling normally. These results have confirmed that trypanosomes adversely affect ovarian activity but it is not known if more long-term damage might have resulted which could affect subsequent fertility

  4. Potential mechanism of the anti-trypanosomal activity of organoruthenium complexes with bioactive thiosemicarbazones.

    Science.gov (United States)

    Demoro, Bruno; Rossi, Miriam; Caruso, Francesco; Liebowitz, Daniel; Olea-Azar, Claudio; Kemmerling, Ulrike; Maya, Juan Diego; Guiset, Helena; Moreno, Virtudes; Pizzo, Chiara; Mahler, Graciela; Otero, Lucía; Gambino, Dinorah

    2013-06-01

    In the search for new metal-based drugs against diseases produced by trypanosomatid parasites, four organoruthenium(II) compounds [Ru2(p-cymene)2(L)2]X2, where L are bioactive 5-nitrofuryl-containing thiosemicarbazones and X = Cl or PF6, had been previously obtained. These compounds had shown activity on Trypanosoma brucei, the etiological agent of African trypanosomiasis. Because of genomic similarities between trypanosomatides, these ruthenium compounds were evaluated, in the current work, on Trypanosoma cruzi, the parasite responsible of American trypanosomiasis (Chagas disease). Two of them showed significant in vitro growth inhibition activity against the infective trypomastigote form of T. cruzi (Dm28c clone, IC50 = 11.69 and 59.42 μM for [Ru2(p-cymene)2(L4)2]Cl2 and [Ru2(p-cymene)2(L1)2]Cl2, respectively, where HL4 = 5-nitrofuryl-N-phenylthiosemicarbazone and HL1 = 5-nitrofurylthiosemicarbazone), showing fairly good selectivities toward trypanosomes with respect to mammalian cells (J774 murine macrophages). Moreover, [Ru2(p-cymene)2(L2)2]Cl2, where HL2 = 5-nitrofuryl-N-methylthiosemicarbazone, was synthesized in order to evaluate the effect of improved solubility on biological behavior. This new chloride salt showed higher activity against T. cruzi than that of the previously synthesized hexafluorophosphate one (Dm28c clone, IC50 = 14.30 μM for the former and 231.3 μM for the latter). In addition, the mode of antitrypanosomal action of the organoruthenium compounds was investigated. The complexes were not only able to generate toxic free radicals through bioreduction but they also interacted with two further potential parasite targets: DNA and cruzipain, a cysteine protease which plays a fundamental role in the biological cycle of these parasites. The results suggest a "multi-target" mechanism of trypanosomicidal action for the obtained complexes. PMID:23564472

  5. Polycistronic trypanosome mRNAs are a target for the exosome

    Science.gov (United States)

    Kramer, Susanne; Piper, Sophie; Estevez, Antonio; Carrington, Mark

    2016-01-01

    Eukaryotic cells have several mRNA quality control checkpoints to avoid the production of aberrant proteins. Intron-containing mRNAs are actively degraded by the nuclear exosome, prevented from nuclear exit and, if these systems fail, degraded by the cytoplasmic NMD machinery. Trypanosomes have only two introns. However, they process mRNAs from long polycistronic precursors by trans-splicing and polycistronic mRNA molecules frequently arise from any missed splice site. Here, we show that RNAi depletion of the trypanosome exosome, but not of the cytoplasmic 5′-3′ exoribonuclease XRNA or the NMD helicase UPF1, causes accumulation of oligocistronic mRNAs. We have also revisited the localization of the trypanosome exosome by expressing eYFP-fusion proteins of the exosome subunits RRP44 and RRP6. Both proteins are significantly enriched in the nucleus. Together with published data, our data suggest a major nuclear function of the trypanosome exosome in rRNA, snoRNA and mRNA quality control. PMID:26946399

  6. Integrity of the core mitochondrial RNA-binding complex 1/nis vital for trypanosome RNA editing

    Czech Academy of Sciences Publication Activity Database

    Huang, Zhenqiu; Faktorová, Drahomíra; Křížová, A.; Kafková, L.; Read, L. K.; Lukeš, Julius; Hashimi, Hassan

    2015-01-01

    Roč. 21, č. 12 (2015), s. 2088-2102. ISSN 1355-8382 R&D Projects: GA ČR GA15-21974S EU Projects: European Commission(XE) 289007 Institutional support: RVO:60077344 Keywords : RNA editing * mitochondrion * trypanosome Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.936, year: 2014

  7. Hemoglobin is a co-factor of human trypanosome lytic factor

    DEFF Research Database (Denmark)

    Widener, Justin; Nielsen, Marianne Jensby; Shiflett, April;

    2007-01-01

    increasing the affinity of TLF for its receptor, and by inducing Fenton chemistry within the trypanosome lysosome. These findings suggest that TLF in uninfected humans may be inactive against T. b. brucei prior to initiation of infection. We propose that infection of humans by T. b. brucei causes hemolysis...

  8. Evaporation induced traversability of the Einstein-Rosen wormhole

    International Nuclear Information System (INIS)

    Suppose the Universe comes into existence (as classical spacetime) already with an empty spherically symmetric macroscopic wormhole present in it. Classically the wormhole would evolve into a part of the Schwarzschild space and thus would not allow any signal to traverse it. I consider semiclassical corrections to that picture and build a model of an evaporating wormhole. The model is based on the assumption that the vacuum polarization and its backreaction on the geometry of the wormhole are weak. The lack of information about the era preceding the emergence of the wormhole results in appearance of three parameters which--along with the initial mass--determine the evolution of the wormhole. For some values of these parameters the wormhole turns out to be long-lived enough to be traversed and to transform into a time machine

  9. CT-FC: more Comprehensive Traversal Focused Crawler

    Directory of Open Access Journals (Sweden)

    NFN Kuspriyanto

    2012-03-01

    Full Text Available In today’s world, people depend more on the WWW information, including professionals who have to analyze the data according their domain to maintain and improve their business. A data analysis would require information that is comprehensive and relevant to their domain. Focused crawler as a topical based Web indexer agent is used to meet this application’s information need. In order to increase the precision, focused crawler face the problem of low recall. The study on WWW hyperlink structure characteristics indicates that many Web documents are not strong connected but through co-citation & co-reference. Conventional focused crawler that uses forward crawling strategy could not visit the documents in these characteristics. This study proposes a more comprehensive traversal framework. As a proof, CT-FC (a focused crawler with the new traversal framework ran on DMOZ data that is representative to WWW characteristics. The results show that this strategy can increase the recall significantly.

  10. On Fusing Recursive Traversals of K-d Trees

    Energy Technology Data Exchange (ETDEWEB)

    Rajbhandari, Samyam; Kim, Jinsung; Krishnamoorthy, Sriram; Pouchet, Louis-Noel; Rastello, Fabrice; Harrison, Robert J.; Sadayappan, Ponnuswamy

    2016-03-17

    Loop fusion is a key program transformation for data locality optimization that is implemented in production compilers. But optimizing compilers currently cannot exploit fusion opportunities across a set of recursive tree traversal computations with producer-consumer relationships. In this paper, we develop a compile-time approach to dependence characterization and program transformation to enable fusion across recursively specified traversals over k-ary trees. We present the FuseT source-to-source code transformation framework to automatically generate fused composite recursive operators from an input program containing a sequence of primitive recursive operators. We use our framework to implement fused operators for MADNESS, Multiresolution Adaptive Numerical Environment for Scientific Simulation. We show that locality optimization through fusion can offer more than an order of magnitude performance improvement.

  11. Evaluation of a Surface Exploration Traverse Analysis and Navigation Tool

    OpenAIRE

    Gilkey, Andrea L.; Galvan, Raquel Christine; Johnson, Aaron William; Kobrick, Ryan L.; Hoffman, Jeffrey A.; Melo, Paulo L.; Newman, Dava

    2011-01-01

    SEXTANT is an extravehicular activity (EVA) mission planner tool developed in MATLAB, which computes the most efficient path between waypoints across a planetary surface. The traverse efficiency can be optimized around path distance, time, or explorer energy consumption. The user can select waypoints and the time spent at each, and can visualize a 3D map of the optimal path. Once the optimal path is generated, the thermal load on suited astronauts or solar power generation of rovers is displa...

  12. Evaporation induced traversability of the Einstein--Rosen wormhole

    OpenAIRE

    Krasnikov, S.

    2005-01-01

    Suppose, the Universe comes into existence (as classical spacetime) already with an empty spherically symmetric macroscopic wormhole present in it. Classically the wormhole would evolve into a part of the Schwarzschild space and thus would not allow any signal to traverse it. I consider semiclassical corrections to that picture and build a model of an evaporating wormhole. The model is based on the assumption that the vacuum polarization and its backreaction on the geometry of the wormhole ar...

  13. Traversable holographic dark energy wormholes constrained by astronomical observations

    CERN Document Server

    Wang, Deng

    2016-01-01

    In this letter, we investigate the traversable wormholes in the holographic dark energy (HDE) model constrained by the modern astronomical observations. First of all, we constrain the HDE model by adopting different data-sets, explore the cosmological background evolution of the HDE model, and find that the HDE model will be fitting better than the Ricci dark energy (RDE) model for the same SNe Ia data-sets by using the the so-called Akaike Information Criterions (AIC) and Bayesian Information Criterions (BIC) . Furthermore, we discover that if taking the SNe Ia data-sets, the wormholes will appear (open) when the redshift $z<0.027$. Subsequently, several specific traversable wormhole solutions are obtained, including the constant redshift function, traceless stress energy tensor, a special choice for the shape function as well as the case of isotropic pressure. Except for the first case, it is very necessary to theoretically construct the traversable wormholes by matching the exterior geometries to the in...

  14. Existence of traversable wormholes in the spherical stellar systems

    Science.gov (United States)

    Övgün, A.; Halilsoy, M.

    2016-07-01

    Potentiality of the presence of traversable wormholes in the outer/inner regions of the halos of galaxies, situated on the Navarro-Frenk-White (NFW) density profile and Universal Rotation Curve (URC) dark matter models have been investigated recently (Rahaman et al. in Eur. Phys. J. C 74:2750, 2014a; Rahaman et al. in Ann. Phys. 350:561-567, 2014b; Kuhfittig in Eur. Phys. J. C 74:2818, 2014a; Kuhfittig in Found. Phys. 7:111-119, 2014b; Kuhfittig in Int. J. Mod. Phys. D 24(03):1550023, 2015; Rahaman et al. in Astrophys. Space Sci. 361(1):37, 2016a; Rahaman et al. in Astrophys. Space Sci. 361(3):90, 2016b). Since this covers our own galaxy also as a possible home for traversable wormholes it prompts us to further the subject by considering alternative density distributions. From this token herein we make use of the Einasto model (Einasto in Tr. Inst. Astrofiz. Alma-Ata 5:87, 1965; Einasto and Haud in Galaxy Astron. Astrophys. 223:89, 1989; Merritt et al. in Astron. J. 132:6, 2006) to describe the density profiles for the same purpose. Our choice for the latter is based on the fact that theoretical dark matter halos produced in computer simulations are best described by such a profile. For technical reasons we trim the number of parameters in the Einasto profile to a possible minimum. Based on such a model it is shown that traversable wormholes in the outer regions of spiral galaxies are possible while the inner part regions prohibit such formations.

  15. Gravito-magnetic monopoles in traversable wormholes from WIMT

    CERN Document Server

    Romero, Jesús Martín

    2016-01-01

    Using Weitzenb\\"ock Induced Matter Theory (WIMT), we study Schwarzschild wormholes performing different foliations on an extended (non-vaccuum) 5D manifold. We explore the geodesic equations for observers which are in the interior of a traversable wormhole and how these observers can detect gravito-magnetic monopoles which are dual to gravito-electric sources observed in the outer zone of some Schwarzschild Black-Hole (BH). The densities of these monopoles are calculated and quantized in the Dirac sense. This kind of duality on the extended Einstein-Maxwell equations, relates electric and magnetic charges on causally disconnected space regions.

  16. APOLLO 16 ASTRONAUTS UNDERGO SIMULATED LUNAR TRAVERSE DURING TRAINING

    Science.gov (United States)

    1972-01-01

    The Apollo 16 flight crew, astronauts Charles M. Duke, Jr., and John W. Young, prepare to undergo a simulated lunar traverse in the training area. The National Aeronautics and Space Administration Apollo 16, the eighth Apollo Lunar landing, is scheduled to land in the mountainous highland region near the crater Descartes to explore the area for a three day period collecting surface material. Making geological observations, and deploying the fourth geophysical station on the Moon. The flight crew of the mission are: John W. Young, commander; Charles M. Duke, Jr., lunar module pilot; and Thomas K. Mattingly II, command module pilot.

  17. Scattering of electromagnetic waves by a traversable wormhole

    Directory of Open Access Journals (Sweden)

    B. Nasr Esfahani

    2005-09-01

    Full Text Available   Replacing the wormhole geometry with an equivalent medium using the perturbation theory of scattering and the Born approximation, we have calculated the differential scattering cross section of electromagnetic waves by a traversable wormhole. It is shown that scattering at long wavelenghts can essentially distinguish wormhole from ordinary scattering object. Some of the zeros of the scattering cross section are determined which can be used for estimating the radius of the throat of wormholes. The known result that in this kind of scattering the linear polarization remains unchanged is verified here.

  18. ArcGIS Digitization of Apollo Surface Traverses

    Science.gov (United States)

    Petro, N. E.; Bleacher, J. E.; Gladdis, L. R.; Garry, W. B.; Lam, F.; Mest, S. C.

    2012-01-01

    The Apollo surface activities were documented in extraordinary detail, with every action performed by the astronauts while on the surface recorded either in photo, audio, film, or by written testimony [1]. The samples and in situ measurements the astronauts collected while on the lunar surface have shaped our understanding of the geologic history of the Moon, and the earliest history and evolution of the inner Solar System. As part of an ongoing LASERfunded effort, we are digitizing and georeferencing data from astronaut traverses and spatially associating them to available, co-registered remote sensing data. Here we introduce the products produced so far for Apollo 15, 16, and 17 missions.

  19. Mixed Boundary Problem for the Traversable Wormhole Models

    OpenAIRE

    Konstantinov, M. Yu.

    1997-01-01

    The conditions of the traversable wormhole joining with the exterior space-time are considered in details and the mixed boundary problem for the Einstein equations is formulated. It is shown that, in opposite to some declarations, the conditions of the wormhole joining with the exterior space-time have non-dynamical nature and can not be defined by the physical processes. The role of these conditions in the formation of the causal structure of space-time is analyzed. It is shown that the caus...

  20. Detection and characterisation of trypanosome strains supposedly resistant to trypanocidal drugs in Senegal

    International Nuclear Information System (INIS)

    In the region of Sokone cattle are constantly exposed to infections with trypanosomes transmitted by Glossina morsitans submorsitans and G. palpalis gambiensis. Trypanocidal drugs are widely used by the farmers on the 50,000 cattle present in the region. Consequently, drug resistance has become a major problem. During the present study goats were inoculated with trypanosome strains isolated from infected cattle. Following the appearance of parasitaemia, the animals were treated with either Berenil, Samorin or Ethidium. The results indicated the parasites were susceptible to Samorin, but one of the Trypanosoma vivax strains showed resistance to Berenil and Ethidium. In addition, the performance of the antigen detection ELISA was compared with that of the Buffy Coat Technique using more than 1000 serum samples from the Sokone region and 100 samples from Northern Senegal infested with tsetse flies. The results showed a very high specificity of 98%. However, additional tests will be necessary to assess the sensitivity properly. (author). 3 refs, 7 tabs

  1. PCR and microsatellite analysis of diminazene aceturate resistance of bovine trypanosomes correlated to knowledge, attitude and practice of livestock keepers in South-Western Ethiopia.

    Science.gov (United States)

    Moti, Y; De Deken, R; Thys, E; Van Den Abbeele, J; Duchateau, L; Delespaux, V

    2015-06-01

    African Animal Trypanosomosis is threatening the agricultural production and cattle breeding more severely than any other livestock disease in the continent, even more since the advent of drug resistance. A longitudinal study was conducted from November 2012 to May 2013 in the Ghibe valley to evaluate diminazene aceturate (DA) resistance and assess livestock owner's perception of trypanocidal drug use. Four Peasant Associations (PAs) were purposively selected and the cattle randomly sampled in each PAs. At the beginning of the study (t0), 106 bovines positive for trypanosomes by the haematocrit centrifugation technique (HCT) and 119 negative control animals were recruited for six months follow-up using HCT, 18S-PCR-RFLP, DpnII-PCR-RFLP and microsatellite analysis. Prevalence of trypanosomosis was 18.1% based on the HCT technique and the mean PCV value was 23.6±5.1% for the 587 sampled cattle. Out of the 106 HCT positive, 64 (60.4%) were positive for the presence of trypanosomes using the 18S-PCR-RFLP. Species detection showed 38 (59.4%) Trypanosoma congolense savannah, 18 (28.1%) Trypanosoma vivax, 5 (7.8%) Trypanosoma theileri and 3 (4.7%) T. congolense Kilifi. Among the T. congolense savannah samples, 31 (81.6%) showed a DA resistant RFLP profile, 2 (5.3%) a mixed profile and 5 did not amplify using the DpnII-PCR-RFLP. A positive HCT had a significant effect on PCV (p<0.001) with the mean PCV value equal to 24.4±0.2% in the absence of trypanosomes and to 20.9±0.3% in the presence of trypanosomes. PCV increased significantly (p<0.001) with 4.4±0.5% one month after treatment. All T. congolense savannah type were analyzed using microsatellite markers TCM1, TCM3 and TCM4. The main events were new infections (40.0%) and relapses (37.5%) with cures lagging at 22.5%. In 10 purposively selected PAs a semi-structured questionnaire was used. The average herd size was the highest in Abelti PA (6.7±1.8 TLU) and the mean herd size was statistically different (p=0.01) in

  2. Benefiting Africans

    Institute of Scientific and Technical Information of China (English)

    ZHANG ZHIPING

    2011-01-01

    Along with thriving Sino-African economic and trade ties,Chinese companies have attached greater importance to their social responsibility to Africans.More than 2,000 sweaters woven by Chinese mothers were sent to orphans and disabled children in Kenya and four other African countries in September.This activity was launched by Hengyuanxiang,a leading Chinese wool manufacturer.

  3. Benefiting Africans

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Along with thriving Sino-African economic and trade ties,Chinese companies have attached greater importance to their social responsibility to Africans.More than 2,000 sweaters woven by Chinese mothers were sent to orphans and disabled children in Kenya and four other African countries in September. This activity was launched by Hengyuanxiang,aleading Chinese wool manufacturer.

  4. Host cell invasion by trypanosomes requires lysosomes and microtubule/kinesin-mediated transport

    OpenAIRE

    1996-01-01

    Invasion of mammalian cells by the protozoan parasite Trypanosoma cruzi occurs by an actin-independent mechanism distinct from phagocytosis. Clusters of host lysosomes are observed at the site of parasite attachment, and lysosomal markers are detected in the vacuolar membrane at early stages of the entry process. These observations led to the hypothesis that the trypanosomes recruit host lysosomes to their attachment site, and that lysosomal fusion serves as a source of membrane to form the p...

  5. The evolution of pathogenic trypanosomes A evolução dos tripanossomas patogênicos

    OpenAIRE

    Stevens, Jamie R; Wendy C. Gibson

    1999-01-01

    In the absence of a fossil record, the evolution of protozoa has until recently largely remained a matter for speculation. However, advances in molecular methods and phylogenetic analysis are now allowing interpretation of the "history written in the genes". This review focuses on recent progress in reconstruction of trypanosome phylogeny based on molecular data from ribosomal RNA, the miniexon and protein-coding genes. Sufficient data have now been gathered to demonstrate unequivocally that ...

  6. Apolipoprotein L-I Promotes Trypanosome Lysis by Forming Pores in Lysosomal Membranes

    Science.gov (United States)

    Pérez-Morga, David; Vanhollebeke, Benoit; Paturiaux-Hanocq, Françoise; Nolan, Derek P.; Lins, Laurence; Homblé, Fabrice; Vanhamme, Luc; Tebabi, Patricia; Pays, Annette; Poelvoorde, Philippe; Jacquet, Alain; Brasseur, Robert; Pays, Etienne

    2005-07-01

    Apolipoprotein L-I is the trypanolytic factor of human serum. Here we show that this protein contains a membrane pore-forming domain functionally similar to that of bacterial colicins, flanked by a membrane-addressing domain. In lipid bilayer membranes, apolipoprotein L-I formed anion channels. In Trypanosoma brucei, apolipoprotein L-I was targeted to the lysosomal membrane and triggered depolarization of this membrane, continuous influx of chloride, and subsequent osmotic swelling of the lysosome until the trypanosome lysed.

  7. Generation of a Nanobody Targeting the Paraflagellar Rod Protein of Trypanosomes

    OpenAIRE

    Obishakin, Emmanuel; Stijlemans, Benoit; Santi-Rocca, Julien; Vandenberghe, Isabel; Devreese, Bart; Muldermans, Serge; Bastin, Philippe; Magez, Stefan

    2014-01-01

    Trypanosomes are protozoan parasites that cause diseases in humans and livestock for which no vaccines are available. Disease eradication requires sensitive diagnostic tools and efficient treatment strategies. Immunodiagnostics based on antigen detection are preferable to antibody detection because the latter cannot differentiate between active infection and cure. Classical monoclonal antibodies are inaccessible to cryptic epitopes (based on their size-150 kDa), costly to produce and require ...

  8. Lunar Surface Potential Increases during Terrestrial Bow Shock Traversals

    Science.gov (United States)

    Collier, Michael R.; Stubbs, Timothy J.; Hills, H. Kent; Halekas, Jasper; Farrell, William M.; Delory, Greg T.; Espley, Jared; Freeman, John W.; Vondrak, Richard R.; Kasper, Justin

    2009-01-01

    Since the Apollo era the electric potential of the Moon has been a subject of interest and debate. Deployed by three Apollo missions, Apollo 12, Apollo 14 and Apollo 15, the Suprathermal Ion Detector Experiment (SIDE) determined the sunlit lunar surface potential to be about +10 Volts using the energy spectra of lunar ionospheric thermal ions accelerated toward the Moon. We present an analysis of Apollo 14 SIDE "resonance" events that indicate the lunar surface potential increases when the Moon traverses the dawn bow shock. By analyzing Wind spacecraft crossings of the terrestrial bow shock at approximately this location and employing current balancing models of the lunar surface, we suggest causes for the increasing potential. Determining the origin of this phenomenon will improve our ability to predict the lunar surface potential in support of human exploration as well as provide models for the behavior of other airless bodies when they traverse similar features such as interplanetary shocks, both of which are goals of the NASA Lunar Science Institute's Dynamic Response of the Environment At the Moon (DREAM) team.

  9. Anti-Trypanosomal Activity of Nigerian Plants and Their Constituents

    Directory of Open Access Journals (Sweden)

    Ngozi Justina Nwodo

    2015-04-01

    Full Text Available African trypanosomiasis is a vector-borne parasitic disease causing serious risks to the lives of about 60 million people and 48 million cattle globally. Nigerian medicinal plants are known to contain a large variety of chemical structures and some of the plant extracts have been screened for antitrypanosomal activity, in the search for potential new drugs against the illness. We surveyed the literatures on plants and plant-derived products with antitrypanosomal activity from Nigerian flora published from 1990 to 2014. About 90 plants were identified, with 54 compounds as potential active agents and presented by plant families in alphabetical order. This review indicates that the Nigerian flora may be suitable as a starting point in searching for new and more efficient trypanocidal molecules.

  10. Infection by trypanosomes in marsupials and rodents associated with human dwellings in Ecuador.

    Science.gov (United States)

    Pinto, C Miguel; Ocaña-Mayorga, Sofía; Lascano, Mauricio S; Grijalva, Mario J

    2006-12-01

    Small mammals trapped in domestic and peridomestic environments of rural Ecuador were screened for trypanosome infection by direct microscopy and hemoculture. Identification of species of trypanosomes was then performed by morphological characteristics and by polymerase chain reaction (PCR) assays. Of 194 animals collected, 15 were positive for infection (7.73%). Eight (4.12%) were infected with Trypanosoma cruzi (1 of 33 Didelphis marsupialis; 7 of 61 Rattus rattus). Eleven R. rattus (18.03%) harbored T. lewisi, 5 of which presented mixed infections with T. cruzi. Additionally, 1 of 3 Oryzomys xanthaeolus was infected with T. rangeli. No trypanosome infection was detected in Philander opossum (n = 1), Mus musculus (n = 79), Rattus norvegicus (n = 8), Akodon orophilus (n = 4), Sigmodon peruanus (n = 3), or Proechimys decumanus (n = 2). Many of the isolates belong to T. cruzi, the causative agent of Chagas disease, and R. rattus had the highest prevalence. Because of its abundance in the study areas, this species is considered an important reservoir for Chagas disease. This is the first report of T. lewisi and T. rangeli in Ecuador. This study is also the first to describe natural mixed infections of T. cruzi-T. lewisi. PMID:17304802

  11. The use of the antigen ELISA for the monitoring of trypanosomal infections in cattle in Zimbabwe

    International Nuclear Information System (INIS)

    The antigen ELISA (Ag-ELISA) for the detection of trypanosomal was used in the diagnosis of bovine trypanosomiasis in Gokwe District, an area from which tsetse flies had been cleared recently; in Hwange Communal Land, which although free from tsetse flies for 20 years, was threatened by reinvasion; and as part of a national survey of vector-borne diseases to determine the extent and prevalence of trypanosomal infections throughout the country. In Gokwe and Hwange all the animals tested were negative for parasites by Buffy Coat Technique (BCT), while the Ag-ELISA results showed that 42.9% and 32.3% respectively of the animals were infected. In the national survey, trypanosomal antigens were detected in cattle at 46.1% of the locations from which samples were collected, most of them in tsetse free areas. These results could be due to reinvasion or persistence of tsetse flies in very small numbers, residual infections of low pathogenicity, or temporary introduction of flies by transport vehicles. (author). 4 refs, 5 figs, 2 tabs

  12. The evolution of pathogenic trypanosomes A evolução dos tripanossomas patogênicos

    Directory of Open Access Journals (Sweden)

    Jamie R. Stevens

    1999-10-01

    Full Text Available In the absence of a fossil record, the evolution of protozoa has until recently largely remained a matter for speculation. However, advances in molecular methods and phylogenetic analysis are now allowing interpretation of the "history written in the genes". This review focuses on recent progress in reconstruction of trypanosome phylogeny based on molecular data from ribosomal RNA, the miniexon and protein-coding genes. Sufficient data have now been gathered to demonstrate unequivocally that trypanosomes are monophyletic; the phylogenetic trees derived can serve as a framework to reinterpret the biology, taxonomy and present day distribution of trypanosome species, providing insights into the coevolution of trypanosomes with their vertebrate hosts and vectors. Different methods of dating the divergence of trypanosome lineages give rise to radically different evolutionary scenarios and these are reviewed. In particular, the use of one such biogeographically based approach provides new insights into the coevolution of the pathogens, Trypanosoma brucei and Trypanosoma cruzi, with their human hosts and the history of the diseases with which they are associated.Os avanços recentes obtidos com os métodos moleculares e com a análise filogenética permitem atualmente interpretar a "história escrita nos genes", na ausência de um registro fóssil. A presente revisão se concentra em avanços recentes na reconstrução da filogenia dos tripanossomas, com base em dados moleculares obtidos do ARN ribossômico, do miniexon e dos genes codificadores de proteínas. Os dados já coletados demonstram inequivocamente que os tripanossomas são monofiléticos; as árvores filogenéticas derivadas podem servir como arcabouço para reinterpretar a biologia, taxonomia e distribuição atual das espécies de tripanossomas, elucidando sua co-evolução com os hospedeiros vertebrados e vetores. Diferentes métodos para datar a divergência das linhagens de

  13. Structures of Trypanosome Vacuolar Soluble Pyrophosphatases: Antiparasitic Drug Targets.

    Science.gov (United States)

    Yang, Yunyun; Ko, Tzu-Ping; Chen, Chun-Chi; Huang, Guozhong; Zheng, Yingying; Liu, Weidong; Wang, Iren; Ho, Meng-Ru; Hsu, Shang-Te Danny; O'Dowd, Bing; Huff, Hannah C; Huang, Chun-Hsiang; Docampo, Roberto; Oldfield, Eric; Guo, Rey-Ting

    2016-05-20

    Trypanosomatid parasites are the causative agents of many neglected tropical diseases, including the leishmaniases, Chagas disease, and human African trypanosomiasis. They exploit unusual vacuolar soluble pyrophosphatases (VSPs), absent in humans, for cell growth and virulence and, as such, are drug targets. Here, we report the crystal structures of VSP1s from Trypanosoma cruzi and T. brucei, together with that of the T. cruzi protein bound to a bisphosphonate inhibitor. Both VSP1s form a hybrid structure containing an (N-terminal) EF-hand domain fused to a (C-terminal) pyrophosphatase domain. The two domains are connected via an extended loop of about 17 residues. Crystallographic analysis and size exclusion chromatography indicate that the VSP1s form tetramers containing head-to-tail dimers. Phosphate and diphosphate ligands bind in the PPase substrate-binding pocket and interact with several conserved residues, and a bisphosphonate inhibitor (BPH-1260) binds to the same site. On the basis of Cytoscape and other bioinformatics analyses, it is apparent that similar folds will be found in most if not all trypanosomatid VSP1s, including those found in insects (Angomonas deanei, Strigomonas culicis), plant pathogens (Phytomonas spp.), and Leishmania spp. Overall, the results are of general interest since they open the way to structure-based drug design for many of the neglected tropical diseases. PMID:26907161

  14. An update of the tsetse fly (Diptera: Glossinidae distribution and African animal trypanosomosis prevalence in north-eastern KwaZulu-Natal, South Africa

    Directory of Open Access Journals (Sweden)

    Chantel J. de Beer

    2016-03-01

    Full Text Available An unpredicted outbreak of African animal trypanosomosis or nagana in 1990 in north-eastern KwaZulu-Natal necessitated an emergency control programme, utilising the extensive cattledipping system in the area, as well as a reassessment of the tsetse and trypanosomosis problem in the province. Since 1990, sporadic blood sampling of cattle at the dip tanks in the naganainfested areas were undertaken to identify trypanosome species involved and to determine the infection prevalence in cattle. The distribution and species composition of the tsetse populations in the area were also investigated. From November 2005 to November 2007 selected dip tanks were surveyed for trypanosome infection prevalence. During April 2005 to August 2009 the distribution and abundance of tsetse populations were assessed with odour-baited H traps. The tsetse and trypanosome distribution maps were updated and potential correlations between tsetse apparent densities (ADs and the prevalence of trypanosomosis were assessed. Glossina brevipalpis Newstead and Glossina austeni Newstead were recorded in locations where they have not previously been collected. No significant correlation between tsetse relative abundance and nagana prevalence was found, which indicated complex interactions between tsetse fly presence and disease prevalence. This was epitomised by data that indicated that despite large differences in the ADs of G. austeni and G. brevipalpis, trypanosome infection prevalence was similar in all three districts in the area. This study clearly indicated that both tsetse species play significant roles in trypanosome transmission and that it will be essential that any control strategy, which aims at sustainable management of the disease, should target both species.Keywords: Tsetse distribution; Glossina brevipalpis; Glossina austeni; trypanosome infection prevalence

  15. The detection and treatment of human African trypanosomiasis

    Directory of Open Access Journals (Sweden)

    Bouteille B

    2012-06-01

    Full Text Available Bernard Bouteille,1 Alain Buguet21Laboratory of Parasitology, Dupuytren University Hospital of Limoges, France; 2Polyclinic Marie-Louise Poto-Djembo, Pointe-Noire, CongoAbstract: Human African trypanosomiasis (HAT is caused by the injection of Trypanosoma brucei (T. b. gambiense or T. b. rhodesiense by Glossina, the tsetse fly. Three historical eras followed the exclusive clinical approach of the 19th century. At the turn of the century, the “initial research” era was initiated because of the dramatic spread of HAT throughout intertropical Africa, and scientists discovered the agent and its vector. Two entities, recurrent fever and sleeping sickness, were then considered a continuum between hemolymphatic stage 1 and meningoencephalitic stage 2. Treatments were developed. Soon after World War I, specific services and mobile teams were created, initiating the “epidemiological” era, during which populations were visited, screened, and treated. As a result, by 1960, annual new cases were rare. New mass screening and staging tools were then developed in a third, “modern” era, especially to counter a new epidemic wave. Currently, diagnosis still relies on microscopic detection of trypanosomes without (wet and thick blood films or with concentration techniques (capillary tube centrifugation, miniature anion-exchange centrifugation technique. Staging is a vital step.Stage 1 patients are treated on site with pentamidine or suramin. However, stage 2 patients are treated in specialized facilities, using drugs that are highly toxic and/or that require complex administration procedures (melarsoprol, eflornithine, or nifurtimox-eflornithine combination therapy. Suramin and melarsoprol are the only medications active against Rhodesian HAT. Staging still relies on cerebrospinal fluid examination for trypanosome detection and white blood cell counts: stage 1, absence of trypanosomes, white blood cell counts ≤ 5/µL; stage 2, presence of

  16. The trypanosome transcriptome is remodelled during differentiation but displays limited responsiveness within life stages

    Directory of Open Access Journals (Sweden)

    Sergeenko Tatiana

    2008-06-01

    Full Text Available Abstract Background Trypanosomatids utilise polycistronic transcription for production of the vast majority of protein-coding mRNAs, which operates in the absence of gene-specific promoters. Resolution of nascent transcripts by polyadenylation and trans-splicing, together with specific rates of mRNA turnover, serve to generate steady state transcript levels that can differ in abundance across several orders of magnitude and can be developmentally regulated. We used a targeted oligonucleotide microarray, representing the strongly developmentally-regulated T. brucei membrane trafficking system and ~10% of the Trypanosoma brucei genome, to investigate both between-stage, or differentiation-dependent, transcriptome changes and within-stage flexibility in response to various challenges. Results 6% of the gene cohort are developmentally regulated, including several small GTPases, SNAREs, vesicle coat factors and protein kinases both consistent with and extending previous data. Therefore substantial differentiation-dependent remodeling of the trypanosome transcriptome is associated with membrane transport. Both the microarray and qRT-PCR were then used to analyse transcriptome changes resulting from specific gene over-expression, knockdown, altered culture conditions and chemical stress. Firstly, manipulation of Rab5 expression results in co-ordinate changes to clathrin protein expression levels and endocytotic activity, but no detectable changes to steady-state mRNA levels, which indicates that the effect is mediated post-transcriptionally. Secondly, knockdown of clathrin or the variant surface glycoprotein failed to perturb transcription. Thirdly, exposure to dithiothreitol or tunicamycin revealed no evidence for a classical unfolded protein response, mediated in higher eukaryotes by transcriptional changes. Finally, altered serum levels invoked little transcriptome alteration beyond changes to expression of ESAG6/7, the transferrin receptor

  17. Improvements on an ELISA to detect trypanosomal antigens and its use as a monitoring tool in tsetse and trypanosomosis control programmes

    International Nuclear Information System (INIS)

    Monoclonal antibodies directed at epitopes of Trypanosoma brucei, T. congolense and T. vivax have been used to capture and detect trypanosomal antigens in bovine blood samples using an enzyme-linked immunosorbent assay (ELISA) developed elsewhere. The test has been transformed in a ready-to-use kit format for distribution among a network of 15 African research institutes. The specificity of the test was assessed under experimental and field conditions and found to be 96% (± 2%) for T. brucei, 99.5% (±1%) for T. congolense and 99% (±1%) for T. vivax. Following a validation period under field conditions, adjustments were made to the protocol to increase the sensitivity of the ELISA and to improve the suitability of the test for laboratory use under African conditions. Presently the ag-ELISA is being applied in conjunction with conventional parasitological techniques such as the buffy coat technique (BCT) to monitor progress in various tsetse and trypanosomosis control programmes and in a tsetse eradication effort in the United Republic of Tanzania, on the island of Zanzibar. The two tests complement each other, since infections not detected by one test may be detected by the other. In general, the serological test tends to produce more false negatives during subacute infections, while the parasitological techniques tend to produce more false negatives during chronic infections. Since the sensitivity of the ELISA is not optimal, research efforts at the FAO/IAEA Agriculture and Biotechnology Laboratory will be focused on improving this aspect. However, these efforts are severely hampered by the lack of a diagnostic test that can be used as a ''gold standard''. The use of the polymerase chain reaction for verifying doubtful test results and as a possible candidate for a ''gold standard'' to diagnose trypanosomosis are discussed. Finally, future plans are outlined to initiate the use of geographical information systems to assess the impact of tsetse control and

  18. A stochastic DNA walker that traverses a microparticle surface

    Science.gov (United States)

    Jung, C.; Allen, P. B.; Ellington, A. D.

    2016-02-01

    Molecular machines have previously been designed that are propelled by DNAzymes, protein enzymes and strand displacement. These engineered machines typically move along precisely defined one- and two-dimensional tracks. Here, we report a DNA walker that uses hybridization to drive walking on DNA-coated microparticle surfaces. Through purely DNA:DNA hybridization reactions, the nanoscale movements of the walker can lead to the generation of a single-stranded product and the subsequent immobilization of fluorescent labels on the microparticle surface. This suggests that the system could be of use in analytical and diagnostic applications, similar to how strand exchange reactions in solution have been used for transducing and quantifying signals from isothermal molecular amplification assays. The walking behaviour is robust and the walker can take more than 30 continuous steps. The traversal of an unprogrammed, inhomogeneous surface is also due entirely to autonomous decisions made by the walker, behaviour analogous to amorphous chemical reaction network computations, which have been shown to lead to pattern formation.

  19. Brane surgery: energy conditions, traversable wormholes, and voids

    International Nuclear Information System (INIS)

    Branes are ubiquitous elements of any low-energy limit of string theory. We point out that negative tension branes violate all the standard energy conditions of the higher-dimensional spacetime they are embedded in; this opens the door to very peculiar solutions of the higher-dimensional Einstein equations. Building upon the (3+1)-dimensional implementation of fundamental string theory, we illustrate the possibilities by considering a toy model consisting of a (2+1)-dimensional brane propagating through our observable (3+1)-dimensional universe. Developing a notion of 'brane surgery', based on the Israel-Lanczos-Sen 'thin shell' formalism of general relativity, we analyze the dynamics and find traversable wormholes, closed baby universes, voids (holes in the spacetime manifold), and an evasion (not a violation) of both the singularity theorems and the positive mass theorem. These features appear generic to any brane model that permits negative tension branes: This includes the Randall-Sundrum models and their variants

  20. GPU accelerated tandem traversal of blocked bounding volume hierarchy collision detection for multibody dynamics

    DEFF Research Database (Denmark)

    Damkjær, Jesper; Erleben, Kenny

    2009-01-01

    simultaneous descend in the tandem traversal. The data structure design and traversal are highly specialized for exploiting the parallel threads in the NVIDIA GPUs. As proof-of-concept we demonstrate a GPU implementation for a multibody dynamics simulation, showing an approximate speedup factor of up to 8...

  1. Optimized traverse planning for future polar prospectors based on lunar topography

    Science.gov (United States)

    Speyerer, E. J.; Lawrence, S. J.; Stopar, J. D.; Gläser, P.; Robinson, M. S.; Jolliff, B. L.

    2016-07-01

    To fully understand the extensive collection of remotely sensed polar observations by the Lunar Reconnaissance Orbiter and other recent lunar missions, we must acquire an array of ground-truth measurements. A polar rover can sample and assay potential polar resources both laterally and at shallow depths. To identify ideal, least-energy traverses for such a polar prospecting mission, we developed a traverse planning tool, called R-Traverse, using a fundamental wheel-regolith interaction model and datasets from the Lunar Reconnaissance Orbiter Camera, Lunar Orbiter Laser Altimeter, and Diviner Lunar Radiometer Experiment. Using the terramechanics model, we identified least-energy traverses at the 20 m scale around Shackleton crater and located one traverse plan that enables the rover to remain illuminated for 94.4% of the lunar year. By incorporating this path planning tool during mission planning, the feasibility of such a mission can be quantified.

  2. Terradynamically streamlined shapes in animals and robots enhance traversability through densely cluttered terrain.

    Science.gov (United States)

    Li, Chen; Pullin, Andrew O; Haldane, Duncan W; Lam, Han K; Fearing, Ronald S; Full, Robert J

    2015-08-01

    Many animals, modern aircraft, and underwater vehicles use fusiform, streamlined body shapes that reduce fluid dynamic drag to achieve fast and effective locomotion in air and water. Similarly, numerous small terrestrial animals move through cluttered terrain where three-dimensional, multi-component obstacles like grass, shrubs, vines, and leaf litter also resist motion, but it is unknown whether their body shape plays a major role in traversal. Few ground vehicles or terrestrial robots have used body shape to more effectively traverse environments such as cluttered terrain. Here, we challenged forest-floor-dwelling discoid cockroaches (Blaberus discoidalis) possessing a thin, rounded body to traverse tall, narrowly spaced, vertical, grass-like compliant beams. Animals displayed high traversal performance (79 ± 12% probability and 3.4 ± 0.7 s time). Although we observed diverse obstacle traversal strategies, cockroaches primarily (48 ± 9% probability) used a novel roll maneuver, a form of natural parkour, allowing them to rapidly traverse obstacle gaps narrower than half their body width (2.0 ± 0.5 s traversal time). Reduction of body roundness by addition of artificial shells nearly inhibited roll maneuvers and decreased traversal performance. Inspired by this discovery, we added a thin, rounded exoskeletal shell to a legged robot with a nearly cuboidal body, common to many existing terrestrial robots. Without adding sensory feedback or changing the open-loop control, the rounded shell enabled the robot to traverse beam obstacles with gaps narrower than shell width via body roll. Such terradynamically 'streamlined' shapes can reduce terrain resistance and enhance traversability by assisting effective body reorientation via distributed mechanical feedback. Our findings highlight the need to consider body shape to improve robot mobility in real-world terrain often filled with clutter, and to develop better locomotor-ground contact models to understand

  3. Intercontinental distribution of a new trypanosome species from Australian endemic Regent Honeyeater (Anthochaera phrygia).

    Science.gov (United States)

    Šlapeta, Jan; Morin-Adeline, Victoria; Thompson, Paul; McDonell, Denise; Shiels, Michael; Gilchrist, Katrina; Votýpka, Jan; Vogelnest, Larry

    2016-07-01

    Establishing a health screening protocol is fundamental for successful captive breeding and release of wildlife. The aim of this study was to undertake a parasitological survey focusing on the presence of trypanosomes in a cohort of Regent Honeyeaters, Anthochaera phrygia, syn. Xanthomyza phrygia (Aves: Passeriformes) that are part of the breeding and reintroduction programme carried out in Australia. We describe a new blood parasite, Trypanosoma thomasbancrofti sp. n. (Kinetoplastida: Trypanosomatidae) with prevalence of 24·4% (20/81) in a captive population in 2015. The sequence of the small subunit rRNA gene (SSU rDNA) and kinetoplast ultrastructure of T. thomasbancrofti sp. n. are the key differentiating characteristics from other Trypanosoma spp. T. thomasbancrofti sp. n. is distinct from Trypanosoma cf. avium found in sympatric Noisy Miners (Manorina melanocephala). The SSU rDNA comparison suggests an intercontinental distribution of T. thomasbancrofti sp. n. and Culex mosquitoes as a suspected vector. Currently, no information exists on the effect of T. thomasbancrofti sp. n. on its hosts; however, all trypanosome-positive birds remain clinically healthy. This information is useful in establishing baseline health data and screening protocols, particularly prior to release to the wild. PMID:27001623

  4. Action of trypanosomal lipolytic enzymes on the membrane-form variant surface glycoprotein of trypanosoma brucei

    International Nuclear Information System (INIS)

    The membrane-form variant surface glycoprotein (mfVSG) of Trypanosoma brucei is anchored in the plasma membrane by myristoyl residues ester-linked to glycerophosphoethanolamine. The authors have extracted [myristoyl-3H]-mfVSG from trypanosomes incubated with [3H]-myristate and have isolated the protein by reverse phase HPLC. The extraction solvent, 20% acetonitrile in 0.1% trifluoroacetic acid, prevents lipolysis of the mfVSG during isolation. The mfVSG was shown to be homogeneous by SDS-PAGE, with an apparent molecular mass ratio of 66,000. No other proteins were labelled with [3H]-myristate. The major lipolytic enzyme of T. brucei, phospholipase A1, did not release myristate from mfVSG to any significant extent, though the enzyme readily hydrolyzes ester linkages of myristoyl phospholipids and p-nitrophenylmyristate. Trypanosomal membranes contain a phosphodiesterase which releases [3H]-1,2-diglyceride from [3H]-myristoyl-mfVSG. The phospholipase A1 can be separated from the myristoyl-releasing activity (phosphodiesterase) by centrifugation, affinity chromatography and anion-exchange chromatography

  5. Action of trypanosomal lipolytic enzymes on the membrane-form variant surface glycoprotein of trypanosoma brucei

    Energy Technology Data Exchange (ETDEWEB)

    Mellors, A.; Forsberg, C.M.; Hambrey, P.N.

    1986-05-01

    The membrane-form variant surface glycoprotein (mfVSG) of Trypanosoma brucei is anchored in the plasma membrane by myristoyl residues ester-linked to glycerophosphoethanolamine. The authors have extracted (myristoyl-/sup 3/H)-mfVSG from trypanosomes incubated with (/sup 3/H)-myristate and have isolated the protein by reverse phase HPLC. The extraction solvent, 20% acetonitrile in 0.1% trifluoroacetic acid, prevents lipolysis of the mfVSG during isolation. The mfVSG was shown to be homogeneous by SDS-PAGE, with an apparent molecular mass ratio of 66,000. No other proteins were labelled with (/sup 3/H)-myristate. The major lipolytic enzyme of T. brucei, phospholipase A/sub 1/, did not release myristate from mfVSG to any significant extent, though the enzyme readily hydrolyzes ester linkages of myristoyl phospholipids and p-nitrophenylmyristate. Trypanosomal membranes contain a phosphodiesterase which releases (/sup 3/H)-1,2-diglyceride from (/sup 3/H)-myristoyl-mfVSG. The phospholipase A/sub 1/ can be separated from the myristoyl-releasing activity (phosphodiesterase) by centrifugation, affinity chromatography and anion-exchange chromatography.

  6. Expression and role of CXCL10 during the encephalitic stage of experimental and clinical African trypanosomiasis

    DEFF Research Database (Denmark)

    Amin, Daniel N; Rottenberg, Martin E; Thomsen, Allan R; Mumba, Dieudonné; Fenger, Christina; Kristensson, Krister; Büscher, Philippe; Finsen, Bente; Masocha, Willias

    2009-01-01

    BACKGROUND: Human African trypanosomiasis, caused by Trypanosoma brucei, involves an early hemolymphatic stage followed by a late encephalitic stage. METHODS: We studied the expression of chemokines with use of microarray and enzyme-linked immunosorbent assay in T. brucei brucei-infected mice and...... in patients with human African trypanosomiasis and examined their role in controlling brain accumulation of T cells and parasites. RESULTS: The messenger RNAs (mRNAs) encoding CXCR3 ligands CXCL9 and CXCL10 demonstrated the greatest increases among chemokines in brain specimens of infected mice, as...... reduced accumulation of trypanosomes and T cells in the brain parenchyma but similar parasitemia levels, compared with wild-type mice. CXCL10 and IFN-gamma levels were increased in the cerebrospinal fluid of patients with late stage but not early stage human African trypanosomiasis. Levels of CXCL10 in...

  7. Time constraints for the Yellow River traversing the Sanmen Gorge

    Science.gov (United States)

    Kong, P.; Jia, J.; Zheng, Y.

    2013-12-01

    The Yellow River is sourced to the northern piedmont of the Bayanhar Mountain Range in the Qinghai Province. It is the second longest river in China, traversing 5464 km. The Yellow River bends like a square in its middle course before traversing the Sanmen Gorge. The Sanmen Gorge is the last gorge in the main course of the Yellow River. After the Sanmen Gorge, the Yellow River flows into vast plains without any barrier, and finally emptys into the Bohai Bay. Thus, the timing of cut-through the Sanmen Gorge implies a true sense of formation and connection of the Yellow River. Drilling in the Weihe Basin, located west of the Sanmen Gorge, shows deposition of over 1000 m lacustrine/fluvial sediments and suggests existence of a paleolake in the basin before the Sanmen Gorge was cut through. The lacustrine/fluvial sequence outcrops at the west bank of the Youhe reservoir is composed of the Sanmen Formation and the Youhe Formation, typical of the sediments in the Weihe Basin. We studied five lacustrine/fluvial phase samples collected from the Youhe reservoir section and three fluvial sand samples relating to transition from lake to fluvial environments from Xihoudu. Our cosmogenic nuclide burial ages suggest that the paleolake formed 2 Ma ago, the transition of the Youhe Formation to the Sanmen Formation occurred 1.8 Ma ago, and the transition from lake to fluvial environment occurred 1.4-1.5 Ma ago. Thick fluvial sands, 90-120 m and 60 m higher than the current water level of the Yellow River, are preserved at Liujiahou and Mapo, respectively, located within the Sanmen Gorge. Dating of these fluvial sands suggests their deposition ages over 1.3 Ma. Zircon U-Pb age distributions of the sands further suggest that Weihe primarily flowed over the Sanmen Gorge 1.3-1.5 Ma ago, followed by the Yellow River cutting through the gorge 1.3-1.4 Ma ago. Previous studies show that the Yellow River appeared at Lanzhou 1.7 Ma ago and running through to the Bohai Bay in the Early

  8. Self-Supervised Learning of Terrain Traversability from Proprioceptive Sensors

    Science.gov (United States)

    Bajracharya, Max; Howard, Andrew B.; Matthies, Larry H.

    2009-01-01

    Robust and reliable autonomous navigation in unstructured, off-road terrain is a critical element in making unmanned ground vehicles a reality. Existing approaches tend to rely on evaluating the traversability of terrain based on fixed parameters obtained via testing in specific environments. This results in a system that handles the terrain well that it trained in, but is unable to process terrain outside its test parameters. An adaptive system does not take the place of training, but supplements it. Whereas training imprints certain environments, an adaptive system would imprint terrain elements and the interactions amongst them, and allow the vehicle to build a map of local elements using proprioceptive sensors. Such sensors can include velocity, wheel slippage, bumper hits, and accelerometers. Data obtained by the sensors can be compared to observations from ranging sensors such as cameras and LADAR (laser detection and ranging) in order to adapt to any kind of terrain. In this way, it could sample its surroundings not only to create a map of clear space, but also of what kind of space it is and its composition. By having a set of building blocks consisting of terrain features, a vehicle can adapt to terrain that it has never seen before, and thus be robust to a changing environment. New observations could be added to its library, enabling it to infer terrain types that it wasn't trained on. This would be very useful in alien environments, where many of the physical features are known, but some are not. For example, a seemingly flat, hard plain could actually be soft sand, and the vehicle would sense the sand and avoid it automatically.

  9. NAT Traversal Capability and Keep-Alive Functionality with IPSec in IKEv2 Implementation

    Directory of Open Access Journals (Sweden)

    CHAMAN SINGH

    2012-02-01

    Full Text Available Since IPv4 Private Networks are behind NAT (Network Address Translation devices. So, to bypass the Binding Update and Binding Acknowledgment by NAT, we need to encapsulate it in UDP (User datagram Protocol Packets. Hence, the Dual Stack Mobile IPv6 should support NAT Traversal and Detection. So for proper securing and fully functionality of NAT traversal, it should be IP Security Protected. Paper presents design and implementation of NAT traversal capability and keeps alive functionality with IP Security in IKEv2 (Internet Key Exchange version 2 implementation for proper Data Communication. It also implements how IPSec integrate with NAT.

  10. Cancer and African Americans

    Science.gov (United States)

    ... Population Profiles > Black/African American > Cancer Cancer and African Americans African Americans have the highest mortality rate ... 65MB] At a glance – Top Cancer Sites for African Americans (2008-2012) Cancer Incidence Rates per 100, ...

  11. Enhancing fuzzy robot navigation systems by mimicking human visual perception of natural terrain traversibility

    Science.gov (United States)

    Tunstel, E.; Howard, A.; Edwards, D.; Carlson, A.

    2001-01-01

    This paper presents a technique for learning to assess terrain traversability for outdoor mobile robot navigation using human-embedded logic and real-time perception of terrain features extracted from image data.

  12. The various vector control activities of the Centre de Recherchers sur les Trypanosomes Animales (CRTA)

    International Nuclear Information System (INIS)

    The role of the centre de recherches sur les trypanosomes animales (CRTA) in anti-tsetse control will become more important because the centre will soon become an institution with a regional mandate. In the laboratory, studies are being carried out on olfactory attractants to riverine species, for instance from reptiles. The persistence and efficiency of pyrethroids are being tested, after impregnation on the tissues used for traps and targets, and after application on cattle. The rearing of ticks is also beginning and CRTA is continuing to rear different species of tsetse fly that can be used by other countries or organizations for their sterile insect technique programmes. In the field, many experiments are being carried out to improve traps and targets (shapes, colours, attractants, etc) and entomological surveys are being carried out regularly in co-ordination with other programmes. (author)

  13. Growth and differentiation on a trypanosome of the subgenus Schizotrypanum from the bat Phyllostomus hastatus

    Directory of Open Access Journals (Sweden)

    Sônia I. Hamanaka

    1993-12-01

    Full Text Available The effects of temperature, pH, osmolarity and aeration on the growth and differentiation of a trypanosome ofthe subgenus Schizotrypanum isolatedfrom the bat Phyllostomus hastatus were studied. In general, the growth characteristics ofthe flagellate were similar to those of Trypanosoma (Schizotrypanum cruzi. However, the parasite did not growth at 33 or 37C. Increase in the osmolarity and aeration promoted growth at 33C. Significant metacyclogenesis was detected only in the growth condition where maximal growth occured (28C, pH 7.3, 380m0s/kg, in tissue cullure flasks, at the end ofthe exponential growth phase. The begining of the metacyclogenesis process was coincident with most glucose utilization and lowest pH. During metacyclogenesis both culture medium pH and osmolarity increased steadly.

  14. Self Sustained Traversable Wormholes Induced by Gravity’s Rainbow and Noncommutative Geometry

    Directory of Open Access Journals (Sweden)

    Garattini Remo

    2013-09-01

    Full Text Available We compare the effects of Noncommutative Geometry and Gravity’s Rainbow on traversable wormholes which are sustained by their own gravitational quantum fluctuations. Fixing the geometry on a well tested model, we find that the final result shows that the wormhole is of the Planckian size. This means that the traversability of the wormhole is in principle, but not in practice.

  15. A Multiple Aminoacyl-tRNA Synthetase Complex That Enhances tRNA-Aminoacylation in African Trypanosomes

    OpenAIRE

    Cestari, Igor; Kalidas, Savitha; Monnerat, Severine; Anupama, Atashi; Phillips, Margaret A.; Stuart, Kenneth

    2013-01-01

    The genes for all cytoplasmic and potentially all mitochondrial aminoacyl-tRNA synthetases (aaRSs) were identified, and all those tested by RNA interference were found to be essential for the growth of Trypanosoma brucei. Some of these enzymes were localized to the cytoplasm or mitochondrion, but most were dually localized to both cellular compartments. Cytoplasmic T. brucei aaRSs were organized in a multiprotein complex in both bloodstream and procyclic forms. The multiple aminoacyl-tRNA syn...

  16. A multiple aminoacyl-tRNA synthetase complex that enhances tRNA-aminoacylation in African trypanosomes.

    Science.gov (United States)

    Cestari, Igor; Kalidas, Savitha; Monnerat, Severine; Anupama, Atashi; Phillips, Margaret A; Stuart, Kenneth

    2013-12-01

    The genes for all cytoplasmic and potentially all mitochondrial aminoacyl-tRNA synthetases (aaRSs) were identified, and all those tested by RNA interference were found to be essential for the growth of Trypanosoma brucei. Some of these enzymes were localized to the cytoplasm or mitochondrion, but most were dually localized to both cellular compartments. Cytoplasmic T. brucei aaRSs were organized in a multiprotein complex in both bloodstream and procyclic forms. The multiple aminoacyl-tRNA synthetase (MARS) complex contained at least six aaRS enzymes and three additional non-aaRS proteins. Steady-state kinetic studies showed that association in the MARS complex enhances tRNA-aminoacylation efficiency, which is in part dependent on a MARS complex-associated protein (MCP), named MCP2, that binds tRNAs and increases their aminoacylation by the complex. Conditional repression of MCP2 in T. brucei bloodstream forms resulted in reduced parasite growth and infectivity in mice. Thus, association in a MARS complex enhances tRNA-aminoacylation and contributes to parasite fitness. The MARS complex may be part of a cellular regulatory system and a target for drug development. PMID:24126051

  17. Phylogeny and morphological variability of trypanosomes from African pelomedusid turtles with redescription of Trypanosoma mocambicum Pienaar, 1962

    Czech Academy of Sciences Publication Activity Database

    Dvořáková, N.; Čepička, I.; Qablan, M. A.; Gibson, W.; Blažek, Radim; Široký, P.

    2015-01-01

    Roč. 166, č. 6 (2015), s. 599-608. ISSN 1434-4610 Institutional support: RVO:68081766 Keywords : Trypanosoma * turtle * Pelusios * polymorphism * phylogeny * SSU rRNA gene Subject RIV: EG - Zoology Impact factor: 3.045, year: 2014

  18. Immunology and immunopathology of African trypanosomiasis

    Directory of Open Access Journals (Sweden)

    Philippe Vincendeau

    2006-12-01

    Full Text Available Major modifications of immune system have been observed in African trypanosomiasis. These immune reactions do not lead to protection and are also involved in immunopathology disorders. The major surface component (variable surface glycoprotein,VSG is associated with escape to immune reactions, cytokine network dysfunctions and autoantibody production. Most of our knowledge result from experimental trypanosomiasis. Innate resistance elements have been characterised. In infected mice, VSG preferentially stimulates a Th 1-cell subset. A response of gd and CD8 T cells to trypanosome antigens was observed in trypanotolerant cattle. An increase in CD5 B cells, responsible for most serum IgM and production of autoantibodies has been noted in infected cattle. Macrophages play important roles in trypanosomiasis, in synergy with antibodies (phagocytosis and by secreting various molecules (radicals, cytokines, prostaglandins,.... Trypanosomes are highly sensitive to TNF-alpha, reactive oxygen and nitrogen intermediates. TNF-alpha is also involved in cachexia. IFN-gamma acts as a parasite growth factor. These various elements contribute to immunosuppression. Trypanosomes have learnt to use immune mechanisms to its own profit. Recent data show the importance of alternative macrophage activation, including arginase induction. L-ornithine produced by host arginase is essential to parasite growth. All these data reflect the deep insight into the immune system realised by trypanosomes and might suggest interference therapeutic approaches.Modificações importantes no sistema imune são observadas na tripanosomíase Africana. Essas reações imunológicas não protegem e estão envolvidas em distúrbios imunopatológicos. O principal componente de superfície (glicoproteína variante de superfície, VSG está associado à evasão das respostas imune, às disfunções da rede de citocinas e à produção de autoanticorpos. Muitos de nossos conhecimentos resultam

  19. Time for pulse traversal through slabs of dispersive and negative (ε, μ) materials

    International Nuclear Information System (INIS)

    The traversal times for an electromagnetic pulse traversing a slab of dispersive and dissipative material with negative dielectric permittivity (ε) and magnetic permeability (μ) have been calculated by using the average flow of electromagnetic energy in the medium. The effects of bandwidth of the pulse and dissipation in the medium have been investigated. While both large bandwidth and large dissipation have similar effects in smoothening out the resonant features that appear due to Fabry-Perot resonances, large dissipation can result in very small or even negative traversal times near the resonant frequencies. We have also investigated the traversal times and Wigner delay times for obliquely incident pulses and evanescent pulses. The coupling to slab plasmon-polariton modes in frequency ranges with negative ε or μ is shown to result in large traversal times at the resonant conditions. We also find that the group velocity mainly contributes to the delay times for pulses propagating across a slab with n=-1. We have checked that the traversal times are positive and subluminal for pulses with sufficiently large bandwidths

  20. Kd-Jump: a path-preserving stackless traversal for faster isosurface raytracing on GPUs.

    Science.gov (United States)

    Hughes, David M; Lim, Ik Soo

    2009-01-01

    Stackless traversal techniques are often used to circumvent memory bottlenecks by avoiding a stack and replacing return traversal with extra computation. This paper addresses whether the stackless traversal approaches are useful on newer hardware and technology (such as CUDA). To this end, we present a novel stackless approach for implicit kd-trees, which exploits the benefits of index-based node traversal, without incurring extra node visitation. This approach, which we term Kd-Jump, enables the traversal to immediately return to the next valid node, like a stack, without incurring extra node visitation (kd-restart). Also, Kd-Jump does not require global memory (stack) at all and only requires a small matrix in fast constant-memory. We report that Kd-Jump outperforms a stack by 10 to 20% and kd-restart by 100%. We also present a Hybrid Kd-Jump, which utilizes a volume stepper for leaf testing and a run-time depth threshold to define where kd-tree traversal stops and volume-stepping occurs. By using both methods, we gain the benefits of empty space removal, fast texture-caching and realtime ability to determine the best threshold for current isosurface and view direction. PMID:19834233

  1. Distinct Phenotypes Caused by Mutation of MSH2 in Trypanosome Insect and Mammalian Life Cycle Forms Are Associated with Parasite Adaptation to Oxidative Stress.

    Directory of Open Access Journals (Sweden)

    Viviane Grazielle-Silva

    2015-06-01

    Full Text Available DNA repair mechanisms are crucial for maintenance of the genome in all organisms, including parasites where successful infection is dependent both on genomic stability and sequence variation. MSH2 is an early acting, central component of the Mismatch Repair (MMR pathway, which is responsible for the recognition and correction of base mismatches that occur during DNA replication and recombination. In addition, recent evidence suggests that MSH2 might also play an important, but poorly understood, role in responding to oxidative damage in both African and American trypanosomes.To investigate the involvement of MMR in the oxidative stress response, null mutants of MSH2 were generated in Trypanosoma brucei procyclic forms and in Trypanosoma cruzi epimastigote forms. Unexpectedly, the MSH2 null mutants showed increased resistance to H2O2 exposure when compared with wild type cells, a phenotype distinct from the previously observed increased sensitivity of T. brucei bloodstream forms MSH2 mutants. Complementation studies indicated that the increased oxidative resistance of procyclic T. brucei was due to adaptation to MSH2 loss. In both parasites, loss of MSH2 was shown to result in increased tolerance to alkylation by MNNG and increased accumulation of 8-oxo-guanine in the nuclear and mitochondrial genomes, indicating impaired MMR. In T. cruzi, loss of MSH2 also increases the parasite capacity to survive within host macrophages.Taken together, these results indicate MSH2 displays conserved, dual roles in MMR and in the response to oxidative stress. Loss of the latter function results in life cycle dependent differences in phenotypic outcomes in T. brucei MSH2 mutants, most likely because of the greater burden of oxidative stress in the insect stage of the parasite.

  2. African dance

    OpenAIRE

    Mumberson, Stephen

    2012-01-01

    The RE Open will be shown at the Mall Gallery London and the international section was judged by major practitioners and educators, print dealers and collectors, President of RE and Keeper of the Ashmolean Museum Dr Bren Unwin, John Purcell, Deborah Roslund, Colin Harrison, Dave Ferry, and Mark Hampson. Piece selected "African Dance" print.

  3. Cooperative Three-Robot System for Traversing Steep Slopes

    Science.gov (United States)

    Stroupe, Ashley; Huntsberger, Terrance; Aghazarian, Hrand; Younse, Paulo; Garrett, Michael

    2009-01-01

    Teamed Robots for Exploration and Science in Steep Areas (TRESSA) is a system of three autonomous mobile robots that cooperate with each other to enable scientific exploration of steep terrain (slope angles up to 90 ). Originally intended for use in exploring steep slopes on Mars that are not accessible to lone wheeled robots (Mars Exploration Rovers), TRESSA and systems like TRESSA could also be used on Earth for performing rescues on steep slopes and for exploring steep slopes that are too remote or too dangerous to be explored by humans. TRESSA is modeled on safe human climbing of steep slopes, two key features of which are teamwork and safety tethers. Two of the autonomous robots, denoted Anchorbots, remain at the top of a slope; the third robot, denoted the Cliffbot, traverses the slope. The Cliffbot drives over the cliff edge supported by tethers, which are payed out from the Anchorbots (see figure). The Anchorbots autonomously control the tension in the tethers to counter the gravitational force on the Cliffbot. The tethers are payed out and reeled in as needed, keeping the body of the Cliffbot oriented approximately parallel to the local terrain surface and preventing wheel slip by controlling the speed of descent or ascent, thereby enabling the Cliffbot to drive freely up, down, or across the slope. Due to the interactive nature of the three-robot system, the robots must be very tightly coupled. To provide for this tight coupling, the TRESSA software architecture is built on a combination of (1) the multi-robot layered behavior-coordination architecture reported in "An Architecture for Controlling Multiple Robots" (NPO-30345), NASA Tech Briefs, Vol. 28, No. 10 (October 2004), page 65, and (2) the real-time control architecture reported in "Robot Electronics Architecture" (NPO-41784), NASA Tech Briefs, Vol. 32, No. 1 (January 2008), page 28. The combination architecture makes it possible to keep the three robots synchronized and coordinated, to use data

  4. Detection of T.b.rhodesiense Trypanosomes in humans and domestic animals in South East Uganda by amplification of serum resistance associated gene

    International Nuclear Information System (INIS)

    The human serum resistance associated (SRA) gene was identified in 28 (80%) of the 35 T.b.rhodesiense Trypanosomes from parasitologically confirmed sleeping sickness cases, using the primers designed by Radwanska and in 27 (77.2%) of the same 35 T.b.rhodesiense Trypanosomes using the primers designed by Gibson. However, about 20% of the 35 T.b.rhodesiense Trypanosomes could not be detected by SRA-PCR even when an aliquot of the first PCR was used in the second PCR, indicating that the gene may be absent in those Trypanosomes or the Trypanosomes could be having another variant of SRA not detectable by these primers since three variants of SRA genes have so far been identified or the amount of Trypanosomal DNA extracted from infected blood was too low to be detected. Since SRA genes resemble variable surface glycoprotein (VSG) genes, it may be that these isolates which are SRA-gene negative are indicative of some T.b.rhodesiense Trypanosomes with modified or lack SRA genes. The number of T.b.rhodesiense isolates which are SRA gene negative are too many to be accounted for as miss identification, but could be explained by simple loss of the SRA gene from the expression site in which it resides during antigenic variation. Analysis of Trypanosomes derived from domestic animals showed that, 79 (90.8%) of the 87 Trypanosomes isolated from cattle were positive by TBR-PCR, indicating that they are Trypanozoon while 8 (9.2%) were negative, suggesting that they could be T.vivax, T.congolense or T.theileri. When subjected to SRA-PCR, 10 (11.5%) of the 87 Trypanosomes isolates derived from cattle were positive, indicating that they could be T.b.rhodesiense circulating in cattle which is similar to the percentage of T.b.rhodesiense previously obtained in cattle in Serere, Soroti district. Some of the SRA-PCR negatives could as well be T.b.rhodesiense since this technique appears to miss some of the parasitologically confirmed cases of T.b.rhodesiense sleeping sickness which

  5. Bats, Trypanosomes, and Triatomines in Ecuador: New Insights into the Diversity, Transmission, and Origins of Trypanosoma cruzi and Chagas Disease

    OpenAIRE

    C. Miguel Pinto; Sofía Ocaña-Mayorga; Tapia, Elicio E.; Lobos, Simón E.; Zurita, Alejandra P.; Fernanda Aguirre-Villacís; Amber MacDonald; Anita G Villacís; Luciana Lima; Teixeira, Marta M. G.; Mario J Grijalva; Perkins, Susan L.

    2015-01-01

    The generalist parasite Trypanosoma cruzi has two phylogenetic lineages associated almost exclusively with bats-Trypanosoma cruzi Tcbat and the subspecies T. c. marinkellei. We present new information on the genetic variation, geographic distribution, host associations, and potential vectors of these lineages. We conducted field surveys of bats and triatomines in southern Ecuador, a country endemic for Chagas disease, and screened for trypanosomes by microscopy and PCR. We identified parasite...

  6. Recent Russian remote sensing investigations in Antarctica within the framework of scientiifc traverses

    Institute of Scientific and Technical Information of China (English)

    Sergey V.Popov

    2015-01-01

    This paper includes a short historical review of Russian and Soviet scientiifc traverses to study the Antarctic inland. The ifrst traverse left on April 2, 1956. It resulted in the opening of the ifrst Russian inland research station named Pionerskaya and provided the ifrst geophysical and glaciological data on regions inland of the Antarctic coast. By 1965, a number of regional inland scientiifc traverses had been completed and the ifrst Atlas of Antarctica was published in 1966. The atlas presented the main achievements of that time. After the discovery of Lake Vostok, Russian scientists commenced remote sensing investigations to study this unique natural phenomenon. The propagation of acoustic and electromagnetic waves in the glacier near Vostok Station were measured to provide important geophysical data. Radio-echo sounding data showed that Lake Vostok is isolated and separated from the rest of the Antarctic subglacial hydrosphere. The total area of the lake is 15 790 km2, excluding 365 km2 occupied by 11 islands. Relfection seismic soundings of Lake Vostok estimated a total volume of about 6 100 km3, an average depth of about 400 m, and a maximum depth of 1 200 m. Since 2008, there have been a number of scientiifc traverses between Mirny and Vostok stations and between Progress and Vostok stations. The data collected during the traverses have provided new insights into sub-ice topography and ice sheet structure, and have led to the discovery of subglacial lakes near Komsomolskaya Station and under Pionerskaya Station.

  7. Breaking the Game: The traversal of the emergent narrative in video games

    Directory of Open Access Journals (Sweden)

    Pedro Cardoso

    2013-12-01

    Full Text Available In video games the player’s actions shape the narrative of their personal experience, molding what otherwise would be a linear course. This emergent narrative is in a state of constant transformation, dependent on how the player influences it. This paper explores how the players traverse ergodic media such as video games and how narrative emerges from the interactions between them and the system. In a previous text we have proposed three types of traversal in video games (Cardoso & Carvalhais, 2013: 1 that in which the player has the ability to choose between mutually exclusive paths; 2 that in which the player has the ability to expand the narrative; and 3 that in which the traversal is determined by the disposition of the other actors in the game world towards the player and each other. This paper intends to further contribute by adding another one: 4 a type of traversal that is rooted in the exploitation of any flaws and glitches in the system, allowing the player to traverse the game through an overlooked side of the algorithm, journeying through a world of unpredictable behaviours and events, that may ultimately break the game altogether.  

  8. Non-existence of static, spherically symmetric and stationary, axisymmetric traversable wormholes coupled to nonlinear electrodynamics

    International Nuclear Information System (INIS)

    In this work we explore the possible existence of static, spherically symmetric and stationary, axisymmetric traversable wormholes coupled to nonlinear electrodynamics. Considering static and spherically symmetric (2 + 1)- and (3 + 1)-dimensional wormhole spacetimes, we verify the presence of an event horizon and the non-violation of the null energy condition at the throat. For the former spacetime, the principle of finiteness is imposed, in order to obtain regular physical fields at the throat. Next, we analyse (2 + 1)-dimensional stationary and axisymmetric wormhole, and also verify the presence of an event horizon, rendering the geometry non-traversable. Relative to (3 + 1)-dimensional stationary and axisymmetric wormhole geometry, we find that the field equations impose specific conditions that are incompatible with the properties of wormholes. Thus, we prove the non-existence of the general class of traversable wormhole solutions, outlined above, within the context of nonlinear electrodynamics

  9. Self-supervised Traversability Assessment in Field Environments with Lidar and Camera

    DEFF Research Database (Denmark)

    Hansen, Mikkel Kragh; Underwood, James; Karstoft, Henrik

    , the visual classifier detects non-traversable image patches as outliers from a Gaussian Mixture Model that maintains the appearance of only traversable ground. Results Our method is evaluated using a diverse dataset of agricultural fields and orchards gathered with a perception research robot developed......Introduction The application of robotic automation within agriculture is increasing. There is a high demand for fully autonomous robots that are both efficient, reliable and affordable. In order to ensure safety, autonomous agricultural vehicles must perceive the environment and detect potential...... obstacles and threats across a variety of environmental conditions. In this paper, a self-supervised framework is proposed, combining laser range sensing from a lidar with images from a monocular camera to reliably assess terrain traversability/navigability. Methods The method uses a near-to-far approach...

  10. Obesity and African Americans

    Science.gov (United States)

    ... Data > Minority Population Profiles > Black/African American > Obesity Obesity and African Americans African American women have the ... ss6304.pdf [PDF | 3.38MB] HEALTH IMPACT OF OBESITY More than 80 percent of people with type ...

  11. Design and implementation of a three axis digitally controlled traverse system for flow surveys in a drying chamber

    OpenAIRE

    Achilleas Bardakas; Vasilis Chasiotis; Dimitrios Tzempelikos; Andronikos Filios

    2014-01-01

    The current paper describes the design and development of a pc-controlled three axis traverse system that aims to serve extensive velocity and temperature measurements into the drying chamber of a laboratory scale convective dryer. The traversing gear design has been conducted based on the convective dryer’s specific experimental requirements and limitations. The fabricated traversing gear uses a trapezoidal lead screw-nut assembly supported by linear ball bearings, coupled with bipolar stepp...

  12. TAC102 Is a Novel Component of the Mitochondrial Genome Segregation Machinery in Trypanosomes

    Science.gov (United States)

    Hoffmann, Anneliese; Haenni, Beat; Jakob, Martin; Schnaufer, Achim; Schimanski, Bernd; Zuber, Benoît; Ochsenreiter, Torsten

    2016-01-01

    Trypanosomes show an intriguing organization of their mitochondrial DNA into a catenated network, the kinetoplast DNA (kDNA). While more than 30 proteins involved in kDNA replication have been described, only few components of kDNA segregation machinery are currently known. Electron microscopy studies identified a high-order structure, the tripartite attachment complex (TAC), linking the basal body of the flagellum via the mitochondrial membranes to the kDNA. Here we describe TAC102, a novel core component of the TAC, which is essential for proper kDNA segregation during cell division. Loss of TAC102 leads to mitochondrial genome missegregation but has no impact on proper organelle biogenesis and segregation. The protein is present throughout the cell cycle and is assembled into the newly developing TAC only after the pro-basal body has matured indicating a hierarchy in the assembly process. Furthermore, we provide evidence that the TAC is replicated de novo rather than using a semi-conservative mechanism. Lastly, we demonstrate that TAC102 lacks an N-terminal mitochondrial targeting sequence and requires sequences in the C-terminal part of the protein for its proper localization. PMID:27168148

  13. Uptake of NO-releasing drugs by the P2 nucleoside transporter in trypanosomes

    Directory of Open Access Journals (Sweden)

    L. Soulère

    1999-11-01

    Full Text Available Nitric oxide (NO· has been identified as a principal regulatory molecule of the immune system and the major cytotoxic mediator of activated immune cells. NO· can also react rapidly with a variety of biological species, particularly with the superoxide radical anion O2·- at almost diffusion-limited rates to form peroxynitrite anion (ONOO-. ONOO- and its proton-catalyzed decomposition products are capable of oxidizing a great diversity of biomolecules and can act as a source of toxic hydroxyl radicals. As a consequence, a strategy for the development of molecules with potential trypanocidal activities could be developed to increase the concentration of nitric oxide in the parasites through NO·-releasing compounds. In this way, the rate of formation of peroxynitrite from NO· and O2·- would be faster than the rate of dismutation of superoxide radicals by superoxide dismutases which constitute the primary antioxidant enzymatic defense system in trypanosomes. The adenosine transport systems of parasitic protozoa, which are also in certain cases implicated in the selective uptake of active drugs such as melarsoprol or pentamidine, could be exploited to specifically target these NO·-releasing compounds inside the parasites. In this work, we present the synthesis, characterization and biological evaluation of a series of molecules that contain both a group which would specifically target these drugs inside the parasites via the purine transporter, and an NO·-donor group that would exert a specific pharmacological effect by increasing NO level, and thus the peroxynitrite concentration inside the parasite.

  14. TAC102 Is a Novel Component of the Mitochondrial Genome Segregation Machinery in Trypanosomes.

    Directory of Open Access Journals (Sweden)

    Roman Trikin

    2016-05-01

    Full Text Available Trypanosomes show an intriguing organization of their mitochondrial DNA into a catenated network, the kinetoplast DNA (kDNA. While more than 30 proteins involved in kDNA replication have been described, only few components of kDNA segregation machinery are currently known. Electron microscopy studies identified a high-order structure, the tripartite attachment complex (TAC, linking the basal body of the flagellum via the mitochondrial membranes to the kDNA. Here we describe TAC102, a novel core component of the TAC, which is essential for proper kDNA segregation during cell division. Loss of TAC102 leads to mitochondrial genome missegregation but has no impact on proper organelle biogenesis and segregation. The protein is present throughout the cell cycle and is assembled into the newly developing TAC only after the pro-basal body has matured indicating a hierarchy in the assembly process. Furthermore, we provide evidence that the TAC is replicated de novo rather than using a semi-conservative mechanism. Lastly, we demonstrate that TAC102 lacks an N-terminal mitochondrial targeting sequence and requires sequences in the C-terminal part of the protein for its proper localization.

  15. Purification of the trypanosome phospholipase C which cleaves the variant surface glycoprotein

    International Nuclear Information System (INIS)

    The surface coat of Trypanosoma brucei is composed of many copies of the Variant Surface Glycoprotein (VSG). This protein is tethered to the cell membrane by a glycolipid moiety which contains dimyristylphosphatidylinositol. Following cell lysis, an endogenous, membrane-bound phospholipase C cleaves the glycolipid and releases the VSG in soluble form. The authors have purified a lipase which they believe is responsible for VSG release. This enzyme, designated VSG lipase, is assayed by measuring release of butanol-soluble 3H from VSG labeled with [3H]myristate. The purification involves detergent extraction of trypanosome membranes, ammonium sulfate fractionation, hydrophobic chromatography, and cation exchange chromatography. The enzyme is purified roughly 2500 fold and is nearly homogeneous. Based on SDS-PAGE, it has an apparent subunit molecular weight of 37,000 daltons. This polypeptide co-fractionates with the activity during several fractionation procedures. The enzyme has an apparent s/sub 20,w/ of 3.8 S. The purified VSG lipase is active in the presence of EDTA; its activity is inhibited by organomercurials and stimulated by dithiothreitol. The purified enzyme releases dimyristylglycerol from VSG

  16. Functionally Graded Aluminum Foam Fabricated by Friction Powder Sintering Process with Traversing Tool

    Science.gov (United States)

    Hangai, Yoshihiko; Morita, Tomoaki; Koyama, Shinji; Kuwazuru, Osamu; Yoshikawa, Nobuhiro

    2016-07-01

    Functionally graded aluminum foam (FG Al foam) is a new class of Al foam in which the pore structure varies over the foam, resulting in corresponding variations in the mechanical properties of the foam. In this study, FG Al foam plates were fabricated by a friction powder sintering (FPS) process with a traversing tool that is based on a previously developed sintering and dissolution process. The variation of the mechanical properties was realized by setting the volume fraction φ of NaCl in the mixture to 60, 70, and 80%. Long FG Al foam plates were fabricated with a length equal to the tool traversing length with φ varying in the tool traversing direction. From x-ray computed tomography observation, it was shown that the density of the Al foam decreased with increasing φ. In contrast, almost uniform pore structures were obtained in each area. According to the results of compression tests on each area, the plateau stress and energy absorption tended to decrease with increasing φ. Therefore, it was shown that FG Al foam plates with varying mechanical properties can be fabricated by the FPS process with the traversing tool.

  17. How to make a traversable wormhole from a Schwarzschild black hole

    OpenAIRE

    Hayward, Sean A.; Koyama, Hiroko

    2004-01-01

    The theoretical construction of a traversable wormhole from a Schwarzschild black hole is described, using analytic solutions in Einstein gravity. The matter model is pure phantom radiation (pure radiation with negative energy density) and the idealization of impulsive radiation is employed.

  18. Seeking exactly solvable models of traversable wormholes supported by phantom energy

    International Nuclear Information System (INIS)

    The purpose of this paper is to obtain exact solutions of the Einstein field equations describing traversable wormholes supported by phantom energy. Their relationship to exact solutions in the literature is also discussed as well as the conditions required to determine such solutions

  19. Peano—A Traversal and Storage Scheme for Octree-Like Adaptive Cartesian Multiscale Grids

    KAUST Repository

    Weinzierl, Tobias

    2011-01-01

    Almost all approaches to solving partial differential equations (PDEs) are based upon a spatial discretization of the computational domain-a grid. This paper presents an algorithm to generate, store, and traverse a hierarchy of d-dimensional Cartesian grids represented by a (k = 3)- spacetree, a generalization of the well-known octree concept, and it also shows the correctness of the approach. These grids may change their adaptive structure throughout the traversal. The algorithm uses 2d + 4 stacks as data structures for both cells and vertices, and the storage requirements for the pure grid reduce to one bit per vertex for both the complete grid connectivity structure and the multilevel grid relations. Since the traversal algorithm uses only stacks, the algorithm\\'s cache hit rate is continually higher than 99.9 percent, and the runtime per vertex remains almost constant; i.e., it does not depend on the overall number of vertices or the adaptivity pattern. We use the algorithmic approach as the fundamental concept for a mesh management for d-dimensional PDEs and for a matrix-free PDE solver represented by a compact discrete 3 d-point operator. In the latter case, one can implement a Jacobi smoother, a Krylov solver, or a geometric multigrid scheme within the presented traversal scheme which inherits the low memory requirements and the good memory access characteristics directly. © 2011 Society for Industrial and Applied Mathematics.

  20. Soil Parameter Identification for Wheel-terrain Interaction Dynamics and Traversability Prediction

    Institute of Scientific and Technical Information of China (English)

    Suksun Hutangkabodee; Yahya Hashem Zweiri; Lakmal Dasarath Seneviratne; Kaspar Althoefer

    2006-01-01

    This paper presents a novel technique for identifying soil parameters for a wheeled vehicle traversing unknown terrain. The identified soil parameters are required for predicting vehicle drawbar pull and wheel drive torque, which in turn can be used for traversability prediction, traction control, and performance optimization of a wheeled vehicle on unknown terrain. The proposed technique is based on the Newton Raphson method. An approximated form of a wheel-soil interaction model based on Composite Simpson's Rule is employed for this purpose. The key soil parameters to be identified are internal friction angle, shear deformation modulus, and lumped pressure-sinkage coefficient. The fourth parameter, cohesion, is not too relevant to vehicle drawbar pull, and is assigned an average value during the identification process. Identified parameters are compared with known values, and shown to be in agreement. The identification method is relatively fast and robust.The identified soil parameters can effectively be used to predict drawbar pull and wheel drive torque with good accuracy.The use of identified soil parameters to design a traversability criterion for wheeled vehicles traversing unknown terrain is presented.

  1. EuroMoonMars Field Campaign: Geology traverse planning using orbital sub-m imagery

    Science.gov (United States)

    Svendsen, Åse; van't Woud, Hans; Samurovic, Dejan; Nebergall, Kent; Battler, Melissa; Orgel, Csilla; Stoker, Carol; Tolboom, Iwan; Foing, Bernard; Team EuroMoonMars

    2013-04-01

    Most of the information we have from Moon and Mars surface, comes from satellite observations. During the selection of landing sites and planning of traverses on unfamiliar planetary sites, satellite images of high resolution is crucial. But what information are we missing from these images? What kind of surprises can be expected when exploring an area that has only been investigated from satellite images? During ILEWG EuroMoonMars 2013 campaign at MDRS Utah we made a comparative study where we looked at satellite images with a spatial resolution of 50-60 cm per pixel, something that is comparable to the resolution of MRO HiRise on Mars or LROC on the Moon. We then planned traverses at MDRS that were as similar to geomorphological features seen at the Gale crater as possible. Following this, we explored these traverses with a rover, drone and walked them in a Mars EVA simulation mode, before taking rocks and soil samples. We shal also discuss the usability of a drone for imaging reconnaissance. The poster will present the results, experiences and lessons learnt from this campaign concerning geological traverse planning based on high resolution satellite images.

  2. Solving the Traveling Salesman's Problem Using the African Buffalo Optimization.

    Science.gov (United States)

    Odili, Julius Beneoluchi; Mohmad Kahar, Mohd Nizam

    2016-01-01

    This paper proposes the African Buffalo Optimization (ABO) which is a new metaheuristic algorithm that is derived from careful observation of the African buffalos, a species of wild cows, in the African forests and savannahs. This animal displays uncommon intelligence, strategic organizational skills, and exceptional navigational ingenuity in its traversal of the African landscape in search for food. The African Buffalo Optimization builds a mathematical model from the behavior of this animal and uses the model to solve 33 benchmark symmetric Traveling Salesman's Problem and six difficult asymmetric instances from the TSPLIB. This study shows that buffalos are able to ensure excellent exploration and exploitation of the search space through regular communication, cooperation, and good memory of its previous personal exploits as well as tapping from the herd's collective exploits. The results obtained by using the ABO to solve these TSP cases were benchmarked against the results obtained by using other popular algorithms. The results obtained using the African Buffalo Optimization algorithm are very competitive. PMID:26880872

  3. The diurnal activity, movement and trypanosome infection rates of Glossina fuscipes fuscipes (Diptera: Glossinidae)in Buvuma Island, Lake Victoria, Uganda

    Institute of Scientific and Technical Information of China (English)

    LONJINO M. OGWAL; ANDREW KALYEBI; JOHN B. KADDU

    2007-01-01

    The diurnal activity patterns, trypanosome infection rates and movement of Glossina fuscipes fuscipes(Diptera: Glossinidae) were investigated in Buvuma Island, Lake Victoria, Uganda. Hourly trapping of tsetse flies was undertaken to determine their activity rhythm while a capture-mark-release-recapture method was conducted to assess the movement and dispersal of tsetse flies between lakeshore, hinterland and further inland sites along a transected area. Dissection of tsetse flies was also undertaken to determine the trypanosome infection rates in salivary glands, proboscis and mid-gut. Results indicated a bimodal diurnal activity profile for G. f. fuscipes on the Island, both on the lakeshore and in the hinterland.Movement and dispersal of G. f. fuscipes tsetse flies occurred between lakeshore, hinterland and further inland sites with a greater tendency of flies to move to the lakeshore. Trypanosome infection rates of 4.32% for Trypasoma vivax and 1.15% for T. congolense were found in G. f. fuscipes.

  4. Mobile robots traversability awareness based on terrain visual sensory data fusion

    Science.gov (United States)

    Shirkhodaie, Amir

    2007-04-01

    In this paper, we have presented methods that significantly improve the robot awareness of its terrain traversability conditions. The terrain traversability awareness is achieved by association of terrain image appearances from different poses and fusion of extracted information from multimodality imaging and range sensor data for localization and clustering environment landmarks. Initially, we describe methods for extraction of salient features of the terrain for the purpose of landmarks registration from two or more images taken from different via points along the trajectory path of the robot. The method of image registration is applied as a means of overlaying (two or more) of the same terrain scene at different viewpoints. The registration geometrically aligns salient landmarks of two images (the reference and sensed images). A Similarity matching techniques is proposed for matching the terrain salient landmarks. Secondly, we present three terrain classifier models based on rule-based, supervised neural network, and fuzzy logic for classification of terrain condition under uncertainty and mapping the robot's terrain perception to apt traversability measures. This paper addresses the technical challenges and navigational skill requirements of mobile robots for traversability path planning in natural terrain environments similar to Mars surface terrains. We have described different methods for detection of salient terrain features based on imaging texture analysis techniques. We have also presented three competing techniques for terrain traversability assessment of mobile robots navigating in unstructured natural terrain environments. These three techniques include: a rule-based terrain classifier, a neural network-based terrain classifier, and a fuzzy-logic terrain classifier. Each proposed terrain classifier divides a region of natural terrain into finite sub-terrain regions and classifies terrain condition exclusively within each sub-terrain region based on

  5. The use of immunoassay method to improve the diagnosis of African trypanosomosis and its application to monitor disease control programmes: A summary

    International Nuclear Information System (INIS)

    The traditional diagnostic techniques for detecting trypanosomes in animals have been the microscopic examination of wet blood films or of thin and thick bloodsmears following fixation and Giemsa staining. The development of concentration methods such as the microhaematocrit centrifuge technique (MHCT) or the buffy coat technique (BCT) using a phase contrast/darkground microscope has improved diagnosis considerably. All these parasitological techniques are very specific (a positive result indicates the true presence of a trypanosome and few false positives are encountered), but generally lack sensitivity. However, in chronically infected animals low parasitaemias often occur, which could not be detected by the most sensitive technique, the BCT method. In 1971 the enzyme-linked immunosorbent assay (ELISA) was developed and various applications of the technique soon proved to be highly sensitive and specific as well as reliable and flexible methods for screening large number of samples. The technique was modified for the detection of trypanosomal antigens and applied for the diagnosis of T. vivax, T. congolense and T. brucei infections in cattle. In experimental infections the test proved to be a sensitive technique for the diagnosis of animal trypanosomosis. Moreover, indications were that the test was well suited for application in developing countries. Consequently, the ELISA was transferred to the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture for distribution to various African research institutes for extensive validation under tropical conditions. 17 refs, 2 tabs

  6. Determinants of Human African Trypanosomiasis Elimination via Paratransgenesis.

    Directory of Open Access Journals (Sweden)

    Jennifer A Gilbert

    2016-03-01

    Full Text Available Human African trypanosomiasis (HAT, transmitted by tsetse flies, has historically infected hundreds of thousands of individuals annually in sub-Saharan Africa. Over the last decade, concerted control efforts have reduced reported cases to below 10,000 annually, bringing complete elimination within reach. A potential technology to eliminate HAT involves rendering the flies resistant to trypanosome infection. This approach can be achieved through the introduction of transgenic Sodalis symbiotic bacteria that have been modified to produce a trypanocide, and propagated via Wolbachia symbionts, which confer a reproductive advantage to the paratransgenic tsetse. However, the population dynamics of these symbionts within tsetse flies have not yet been evaluated. Specifically, the key factors that determine the effectiveness of paratransgenesis have yet to be quantified. To identify the impact of these determinants on T.b. gambiense and T.b. rhodesiense transmission, we developed a mathematical model of trypanosome transmission that incorporates tsetse and symbiont population dynamics. We found that fecundity and mortality penalties associated with Wolbachia or recombinant Sodalis colonization, probabilities of vertical transmission, and tsetse migration rates are fundamental to the feasibility of HAT elimination. For example, we determined that HAT elimination could be sustained over 25 years when Wolbachia colonization minimally impacted fecundity or mortality, and when the probability of recombinant Sodalis vertical transmission exceeded 99.9%. We also found that for a narrow range of recombinant Sodalis vertical transmission probability (99.9-90.6% for T.b. gambiense and 99.9-85.8% for T.b. rhodesiense, cumulative HAT incidence was reduced between 30% and 1% for T.b. gambiense and between 21% and 3% for T.b. rhodesiense, although elimination was not predicted. Our findings indicate that fitness and mortality penalties associated with paratransgenic

  7. Trans mRNA splicing in trypanosomes: cloning and analysis of a PRP8-homologous gene from Trypanosoma brucei provides evidence for a U5-analogous RNP.

    OpenAIRE

    Lücke, S.; Klöckner, T; Palfi, Z.; Boshart, M; Bindereif, A

    1997-01-01

    In trypanosomes all mRNAs are generated through trans mRNA splicing, requiring the functions of the small nuclear RNAs U2, U4 and U6. In the absence of conventional cis mRNA splicing, the structure and function of a U5-analogous snRNP in trypanosomes has remained an open question. In cis splicing, a U5 snRNP-specific protein component called PRP8 in yeast and p220 in man is a highly conserved, essential splicing factor involved in splice-site recognition and selection. We have cloned and sequ...

  8. The trypanosome Pumilio-domain protein PUF7 associates with a nuclear cyclophilin and is involved in ribosomal RNA maturation.

    Science.gov (United States)

    Droll, Dorothea; Archer, Stuart; Fenn, Katelyn; Delhi, Praveen; Matthews, Keith; Clayton, Christine

    2010-03-19

    Proteins with Pumilio RNA binding domains (Puf proteins) are ubiquitous in eukaryotes. Some Puf proteins bind to the 3'-untranslated regions of mRNAs, acting to repress translation and promote degradation; others are involved in ribosomal RNA maturation. The genome of Trypanosoma brucei encodes eleven Puf proteins whose function cannot be predicted by sequence analysis. We show here that epitope-tagged TbPUF7 is located in the nucleolus, and associated with a nuclear cyclophilin-like protein, TbNCP1. RNAi targeting PUF7 reduced trypanosome growth and inhibited two steps in ribosomal RNA processing. PMID:20153321

  9. PNT1 Is a C11 Cysteine Peptidase Essential for Replication of the Trypanosome Kinetoplast.

    Science.gov (United States)

    Grewal, Jaspreet S; McLuskey, Karen; Das, Debanu; Myburgh, Elmarie; Wilkes, Jonathan; Brown, Elaine; Lemgruber, Leandro; Gould, Matthew K; Burchmore, Richard J; Coombs, Graham H; Schnaufer, Achim; Mottram, Jeremy C

    2016-04-29

    The structure of a C11 peptidase PmC11 from the gut bacterium, Parabacteroides merdae, has recently been determined, enabling the identification and characterization of a C11 orthologue, PNT1, in the parasitic protozoon Trypanosoma brucei. A phylogenetic analysis identified PmC11 orthologues in bacteria, archaea, Chromerids, Coccidia, and Kinetoplastida, the latter being the most divergent. A primary sequence alignment of PNT1 with clostripain and PmC11 revealed the position of the characteristic His-Cys catalytic dyad (His(99) and Cys(136)), and an Asp (Asp(134)) in the potential S1 binding site. Immunofluorescence and cryoelectron microscopy revealed that PNT1 localizes to the kinetoplast, an organelle containing the mitochondrial genome of the parasite (kDNA), with an accumulation of the protein at or near the antipodal sites. Depletion of PNT1 by RNAi in the T. brucei bloodstream form was lethal both in in vitro culture and in vivo in mice and the induced population accumulated cells lacking a kinetoplast. In contrast, overexpression of PNT1 led to cells having mislocated kinetoplasts. RNAi depletion of PNT1 in a kDNA independent cell line resulted in kinetoplast loss but was viable, indicating that PNT1 is required exclusively for kinetoplast maintenance. Expression of a recoded wild-type PNT1 allele, but not of an active site mutant restored parasite viability after induction in vitro and in vivo confirming that the peptidase activity of PNT1 is essential for parasite survival. These data provide evidence that PNT1 is a cysteine peptidase that is required exclusively for maintenance of the trypanosome kinetoplast. PMID:26940875

  10. PNT1 Is a C11 Cysteine Peptidase Essential for Replication of the Trypanosome Kinetoplast*

    Science.gov (United States)

    Das, Debanu; Myburgh, Elmarie; Wilkes, Jonathan; Brown, Elaine; Lemgruber, Leandro; Gould, Matthew K.; Burchmore, Richard J.; Coombs, Graham H.; Schnaufer, Achim

    2016-01-01

    The structure of a C11 peptidase PmC11 from the gut bacterium, Parabacteroides merdae, has recently been determined, enabling the identification and characterization of a C11 orthologue, PNT1, in the parasitic protozoon Trypanosoma brucei. A phylogenetic analysis identified PmC11 orthologues in bacteria, archaea, Chromerids, Coccidia, and Kinetoplastida, the latter being the most divergent. A primary sequence alignment of PNT1 with clostripain and PmC11 revealed the position of the characteristic His-Cys catalytic dyad (His99 and Cys136), and an Asp (Asp134) in the potential S1 binding site. Immunofluorescence and cryoelectron microscopy revealed that PNT1 localizes to the kinetoplast, an organelle containing the mitochondrial genome of the parasite (kDNA), with an accumulation of the protein at or near the antipodal sites. Depletion of PNT1 by RNAi in the T. brucei bloodstream form was lethal both in in vitro culture and in vivo in mice and the induced population accumulated cells lacking a kinetoplast. In contrast, overexpression of PNT1 led to cells having mislocated kinetoplasts. RNAi depletion of PNT1 in a kDNA independent cell line resulted in kinetoplast loss but was viable, indicating that PNT1 is required exclusively for kinetoplast maintenance. Expression of a recoded wild-type PNT1 allele, but not of an active site mutant restored parasite viability after induction in vitro and in vivo confirming that the peptidase activity of PNT1 is essential for parasite survival. These data provide evidence that PNT1 is a cysteine peptidase that is required exclusively for maintenance of the trypanosome kinetoplast. PMID:26940875

  11. Growth and differentiation on a trypanosome of the subgenus Schizotrypanum from the bat Phyllostomus hastatus

    Directory of Open Access Journals (Sweden)

    Sônia I. Hamanaka

    1993-12-01

    Full Text Available The effects of temperature, pH, osmolarity and aeration on the growth and differentiation of a trypanosome ofthe subgenus Schizotrypanum isolatedfrom the bat Phyllostomus hastatus were studied. In general, the growth characteristics ofthe flagellate were similar to those of Trypanosoma (Schizotrypanum cruzi. However, the parasite did not growth at 33 or 37C. Increase in the osmolarity and aeration promoted growth at 33C. Significant metacyclogenesis was detected only in the growth condition where maximal growth occured (28C, pH 7.3, 380m0s/kg, in tissue cullure flasks, at the end ofthe exponential growth phase. The begining of the metacyclogenesis process was coincident with most glucose utilization and lowest pH. During metacyclogenesis both culture medium pH and osmolarity increased steadly.Foram estudados os efeitos da temperatura, do pH, da osmolaridade e da areaçâo sobre o crescimento e a diferenciação de um tripanosoma do subgenêro Schizotrypanum, isolado do morcego Phyllostomus hastatus. Em geral, as características do crescimento do flagelado foram semelhantes àquelas do Trypanosoma (Schizotrypanum cruzi. Entretanto, o parasita não de desenvolveu a 33 ou 37°C. O aumento na osmolaridade e areaçâo estimulou o crescimento a 33°C. Metaciclogênese sifhificativa foi detectada somente na condição de crescimento, onde ocorreu desenvolvimento máximo (28°C, pH 7.3, 320m0/kg H20, em frascos de cultura de tecido, no final da fase do crescimento exponencial. O início do processo de metaciclogênese coincidiu com maior utilização de glucose e menor pH. Durante a metaciclogênese, o pHdo meio de cultura e a osmolaridade aumentaram constantemente.

  12. Graphical control and evaluation of the operational performance of ELISA method for detection of trypanosomal antibodies

    International Nuclear Information System (INIS)

    The performance of four indirect trypanosomal antibody detection enzyme-linked immunosorbent assays (I-TAB ELISA's), exploiting native and denatured antigens of Trypanosoma congolense (T.c.AGn, T.c.AGd) and T. vivax (T.v.AGn, T.v.AGd), has been evaluated in fifteen laboratories from Africa and Europe. Standardised internal quality control samples (IQCs) were used as indicators and data plotted on charts to monitor and control the ELISA's at individual laboratories. Based on the overall data, dispersion of true values from the population data range was estimated plotting the location and deviation of raw and normalised absorbance values of the IQCs. Binding ratios were calculated to estimate the assay proficiency with respect to the accuracy of assessing that the QC samples tested positive or negative in the test proper. The frequency distribution of coefficients of variation <10% of IQCs was monitored. The use of this standardised and transparent IQC data charting provides a useful quality control tool for the evaluation of the performance of the ELISA's used for trypanosomosis serology. The method provides a measure of confidence in estimating the proficiency of national laboratories with respect to reported ELISA results on disease occurrence. Moreover, data were compiled of the inter-laboratory ELISA performance by means of summary data charts with reference to the performance criteria described. The data were also analysed using modified Youden plots. The analysis demonstrated similar laboratory proficiency for the I-TAB ELISA (T.c.AGn) (four of five laboratories), I-TAB ELISA (T.c.AGd) (eleven of fourteen laboratories), I-TAB ELISA (T.v.AGn) (three of five laboratories), and I-TAB ELISA (T.v.AGd) (eleven of fifteen laboratories). The impact of data variation between test and specified values as a sole decision criterion for acceptance or rejection of test plates is discussed. (author)

  13. The ecotopes and evolution of triatomine bugs (triatominae and their associated trypanosomes

    Directory of Open Access Journals (Sweden)

    Gaunt Michael

    2000-01-01

    Full Text Available Triatomine bug species such as Microtriatoma trinidadensis, Eratyrus mucronatus, Belminus herreri, Panstrongylus lignarius, and Triatoma tibiamaculata are exquisitely adapted to specialist niches. This suggests a long evolutionary history, as well as the recent dramatic spread a few eclectic, domiciliated triatomine species. Virtually all species of the genus Rhodnius are primarily associated with palms. The genus Panstrongylus is predominantly associated with burrows and tree cavities and the genus Triatoma with terrestrial rocky habitats or rodent burrows. Two major sub-divisions have been defined within the species Trypanosoma cruzi, as T. cruzi 1 (Z1 and T. cruzi 2 (Z2. The affinities of a third group (Z3 are uncertain. Host and habitat associations lead us to propose that T. cruzi 1 (Z1 has evolved in an arboreal, palm tree habitat with the triatomine tribe Rhodniini, in association with the opossum Didelphis. Similarly we propose that T. cruzi (Z2 and Z3 evolved in a terrestrial habitat in burrows and in rocky locations with the triatomine tribe Triatomini, in association with edentates, and/or possibly ground dwelling marsupials. Both sub-divisions of T. cruzi may have been contemporary in South America up to 65 million years ago. Alternatively, T. cruzi 2 (Z2 may have evolved more recently from T. cruzi 1 (Z1 by host transfers into rodents, edentates, and primates. We have constructed a molecular phylogeny of haematophagous vectors, including triatomine bugs, which suggests that faecal transmission of trypanosomes may be the ancestral route. A molecular clock phylogeny suggests that Rhodnius and Triatoma diverged before the arrival, about 40 million years ago, of bats and rodents into South America.

  14. Genome of the avirulent human-infective trypanosome--Trypanosoma rangeli.

    Directory of Open Access Journals (Sweden)

    Patrícia Hermes Stoco

    2014-09-01

    Full Text Available Trypanosoma rangeli is a hemoflagellate protozoan parasite infecting humans and other wild and domestic mammals across Central and South America. It does not cause human disease, but it can be mistaken for the etiologic agent of Chagas disease, Trypanosoma cruzi. We have sequenced the T. rangeli genome to provide new tools for elucidating the distinct and intriguing biology of this species and the key pathways related to interaction with its arthropod and mammalian hosts.The T. rangeli haploid genome is ∼ 24 Mb in length, and is the smallest and least repetitive trypanosomatid genome sequenced thus far. This parasite genome has shorter subtelomeric sequences compared to those of T. cruzi and T. brucei; displays intraspecific karyotype variability and lacks minichromosomes. Of the predicted 7,613 protein coding sequences, functional annotations could be determined for 2,415, while 5,043 are hypothetical proteins, some with evidence of protein expression. 7,101 genes (93% are shared with other trypanosomatids that infect humans. An ortholog of the dcl2 gene involved in the T. brucei RNAi pathway was found in T. rangeli, but the RNAi machinery is non-functional since the other genes in this pathway are pseudogenized. T. rangeli is highly susceptible to oxidative stress, a phenotype that may be explained by a smaller number of anti-oxidant defense enzymes and heat-shock proteins.Phylogenetic comparison of nuclear and mitochondrial genes indicates that T. rangeli and T. cruzi are equidistant from T. brucei. In addition to revealing new aspects of trypanosome co-evolution within the vertebrate and invertebrate hosts, comparative genomic analysis with pathogenic trypanosomatids provides valuable new information that can be further explored with the aim of developing better diagnostic tools and/or therapeutic targets.

  15. Trypanosome Lytic Factor-1 Initiates Oxidation-stimulated Osmotic Lysis of Trypanosoma brucei brucei.

    Science.gov (United States)

    Greene, Amy Styer; Hajduk, Stephen L

    2016-02-01

    Human innate immunity against the veterinary pathogen Trypanosoma brucei brucei is conferred by trypanosome lytic factors (TLFs), against which human-infective T. brucei gambiense and T. brucei rhodesiense have evolved resistance. TLF-1 is a subclass of high density lipoprotein particles defined by two primate-specific apolipoproteins: the ion channel-forming toxin ApoL1 (apolipoprotein L1) and the hemoglobin (Hb) scavenger Hpr (haptoglobin-related protein). The role of oxidative stress in the TLF-1 lytic mechanism has been controversial. Here we show that oxidative processes are involved in TLF-1 killing of T. brucei brucei. The lipophilic antioxidant N,N'-diphenyl-p-phenylenediamine protected TLF-1-treated T. brucei brucei from lysis. Conversely, lysis of TLF-1-treated T. brucei brucei was increased by the addition of peroxides or thiol-conjugating agents. Previously, the Hpr-Hb complex was postulated to be a source of free radicals during TLF-1 lysis. However, we found that the iron-containing heme of the Hpr-Hb complex was not involved in TLF-1 lysis. Furthermore, neither high concentrations of transferrin nor knock-out of cytosolic lipid peroxidases prevented TLF-1 lysis. Instead, purified ApoL1 was sufficient to induce lysis, and ApoL1 lysis was inhibited by the antioxidant DPPD. Swelling of TLF-1-treated T. brucei brucei was reminiscent of swelling under hypotonic stress. Moreover, TLF-1-treated T. brucei brucei became rapidly susceptible to hypotonic lysis. T. brucei brucei cells exposed to peroxides or thiol-binding agents were also sensitized to hypotonic lysis in the absence of TLF-1. We postulate that ApoL1 initiates osmotic stress at the plasma membrane, which sensitizes T. brucei brucei to oxidation-stimulated osmotic lysis. PMID:26645690

  16. Bioluminescence Imaging to Detect Late Stage Infection of African Trypanosomiasis.

    Science.gov (United States)

    Burrell-Saward, Hollie; Ward, Theresa H

    2016-01-01

    Human African trypanosomiasis (HAT) is a multi-stage disease that manifests in two stages; an early blood stage and a late stage when the parasite invades the central nervous system (CNS). In vivo study of the late stage has been limited as traditional methodologies require the removal of the brain to determine the presence of the parasites. Bioluminescence imaging is a non-invasive, highly sensitive form of optical imaging that enables the visualization of a luciferase-transfected pathogen in real-time. By using a transfected trypanosome strain that has the ability to produce late stage disease in mice we are able to study the kinetics of a CNS infection in a single animal throughout the course of infection, as well as observe the movement and dissemination of a systemic infection. Here we describe a robust protocol to study CNS infections using a bioluminescence model of African trypanosomiasis, providing real time non-invasive observations which can be further analyzed with optional downstream approaches. PMID:27284970

  17. Limestone Microfacies of Baturaja Formation along Air Rambangnia Traverse, South OKU, South Sumatra

    Directory of Open Access Journals (Sweden)

    Sigit Maryanto

    2014-07-01

    Full Text Available DOI: 10.17014/ijog.v1i1.173Limestones of the Baturaja Formation occur at Air Rambangnia traverse, South Ogan Komering Ulu, South Sumatra, and they are used as objects for microfacies studies. The microfacies studies are based on a detailed petro­graphic analysis of thirty four limestone samples, taken from the traverse. Four types of the limestones are identified such as wackestone, packstone, grainstone, and floatstone. At least five microfacies form the limestone succesion of the Baturaja Formation. They are interpreted as sedimentary facies of very restricted bay and pond, back reef local slope, slope and shelf edge, winnowed platform edge sand, and reef flank facies.  

  18. Transmission coefficient, resonant tunneling lifetime and traversal time in multibarrier semiconductor heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Nanda, Jyotirmayee [Department of Physics, National Institute of Technology, Rourkela, 769008 (India)]. E-mail: jnanda_b9@rediffmail.com; Mahapatra, P.K. [Department of Physics and Technophysics, Vidyasagar University, Midnapore, 721102 (India)]. E-mail: pkmahapatra@vidyasagar.ac.in; Roy, C.L. [Department of Physics and Meterology, Indian Institute of Technology, Kharagpur, 721302 (India)

    2006-09-01

    A computational model based on non-relativistic approach is proposed for the determination of transmission coefficient, resonant tunneling energies, group velocity, resonant tunneling lifetime and traversal time in multibarrier systems (GaAs/Al {sub y} Ga{sub 1-} {sub y} As) for the entire energy range {epsilon}V {sub 0}, V {sub 0}, being the potential barrier height. The resonant energy states were found to group into allowed tunneling bands separated by forbidden gaps. The tunneling lifetime and the traversal time are found to have minimum values at the middle of each allowed band. Further, It is observed that the electrons with energies in the higher tunneling band could tunnel out faster than those with energies in the lower band. Moreover, an additional resonant peak in resonant energy spectrum indicated the presence of a surface state where resonant tunneling occurs.

  19. Validation of an improved enzyme-linked immunosorbent assay for the diagnosis of trypanosomal antibodies in Ghanaian cattle

    International Nuclear Information System (INIS)

    The validation of an enzyme-linked immunosorbent assay (Ab-ELISA) for the detection of antibodies to pathogenic trypanosomes in cattle is described. Two hundred known negative sera obtained from the tsetse-free zone of Dori (Burkina Faso) were analyzed using microtitre plates pre-coated with crude antigen lysates of Trypanosoma congolense and T. vivax. A pre-test optimization was carried out and a percent positivity (PP) of 50% was chosen (specificity: >82%) for assaying field sera. A total of 440 serum samples collected from cattle in areas of known and unknown disease prevalence were assayed. For all animals the packed red cell volume (PCV) was determined and the buffy coat technique (BCT) and blood smears were examined to detect trypanosomes at the species level. A comparison of the BCT and Ab-ELISA results showed there was a much higher prevalence of antibodies to both species than the parasite prevalence as shown by the BCT (10 fold). The rate of agreement between BCT-positive and Ab-ELISA-positive samples for both species was low (<10%). No conclusion could be drawn from this finding because of the low number of known BCT positive cases that were identified. There was a better, albeit highly variable, agreement between BCT-negative and Ab-ELISA-negative samples (30-70%). Proposals for further improvement of the Ab-ELISA and prospects for the use of the assay in the monitoring of trypanosomosis control in Ghana are discussed. (author)

  20. Feeding sources and trypanosome infection index of Rhodnius pallescens in a Chagas disease endemic area of Amador County, Panama.

    Science.gov (United States)

    Pineda, Vanessa; Montalvo, Edilma; Alvarez, Dayra; Santamaría, Ana María; Calzada, Jose Eduardo; Saldaña, Azael

    2008-01-01

    The sylvatic triatomine Rhodnius pallescens is considered to be the most important and widespread vector of Trypanosoma cruzi and Trypanosoma rangeli in Panama. However, its behavior and biological characteristics have only been partially investigated. Thus, to achieve sustainable and efficient control over Chagas disease in Panama, a better understanding of the ecology and biology of R. pallescens is essential. In this study we evaluated R. pallescens host feeding sources using a dot-blot assay, and the trypanosome infection index by PCR analysis in a Chagas disease endemic area of central Panama. It was found that in peridomestic palm trees, 20.3% of the examined bugs had fed on opossums (Didelphis marsupialis). However, we observed an increased anthropophagy (25.4%) for those bugs collected inside houses. Considering the domestic and peridomestic habitats as a whole, the proportion of collected R. pallescens infected with trypanosomes was 87.4%. In the two habitats the predominant infection was with T. cruzi (80-90%). Between 47-51% of the analyzed triatomines were infected with T. rangeli. Mixed infections (40-51%) were also detected. These findings provide a better basis for the implementation of a rational control and surveillance program for Chagas disease in regions where R. pallescens is endemic. PMID:18488091

  1. Bats, Trypanosomes, and Triatomines in Ecuador: New Insights into the Diversity, Transmission, and Origins of Trypanosoma cruzi and Chagas Disease.

    Directory of Open Access Journals (Sweden)

    C Miguel Pinto

    Full Text Available The generalist parasite Trypanosoma cruzi has two phylogenetic lineages associated almost exclusively with bats-Trypanosoma cruzi Tcbat and the subspecies T. c. marinkellei. We present new information on the genetic variation, geographic distribution, host associations, and potential vectors of these lineages. We conducted field surveys of bats and triatomines in southern Ecuador, a country endemic for Chagas disease, and screened for trypanosomes by microscopy and PCR. We identified parasites at species and genotype levels through phylogenetic approaches based on 18S ribosomal RNA (18S rRNA and cytochrome b (cytb genes and conducted a comparison of nucleotide diversity of the cytb gene. We document for the first time T. cruzi Tcbat and T. c. marinkellei in Ecuador, expanding their distribution in South America to the western side of the Andes. In addition, we found the triatomines Cavernicola pilosa and Triatoma dispar sharing shelters with bats. The comparisons of nucleotide diversity revealed a higher diversity for T. c. marinkellei than any of the T. c. cruzi genotypes associated with Chagas disease. Findings from this study increased both the number of host species and known geographical ranges of both parasites and suggest potential vectors for these two trypanosomes associated with bats in rural areas of southern Ecuador. The higher nucleotide diversity of T. c. marinkellei supports a long evolutionary relationship between T. cruzi and bats, implying that bats are the original hosts of this important parasite.

  2. View of rim of South Ray crater on traverse up Stone Mountain during EVA

    Science.gov (United States)

    1972-01-01

    A view of the rim of South Ray crater photographed with a 500mm lens from Station no.4 -- the highest point on the traverse up Stone Mountain -- during the second Apollo 16 extravehicular activity (EVA-2) at the Descartes landing site. South Ray crater was a 'fresh' source of angular ejecta in the Lunar Module-Apollo Lunar Surface Experiments Package area and for samples at Station No.8.

  3. Fate of the first traversible wormhole: black-hole collapse or inflationary expansion

    OpenAIRE

    Shinkai, Hisa-aki; Hayward, Sean A.

    2002-01-01

    We study numerically the stability of Morris & Thorne's first traversible wormhole, shown previously by Ellis to be a solution for a massless ghost Klein-Gordon field. Our code uses a dual-null formulation for spherically symmetric space-time integration, and the numerical range covers both universes connected by the wormhole. We observe that the wormhole is unstable against Gaussian pulses in either exotic or normal massless Klein-Gordon fields. The wormhole throat suffers a bifurcation of h...

  4. Traversable wormhole in the deformed Ho\\v{r}ava-Lifshitz gravity

    OpenAIRE

    Son, Edwin J.; Kim, Wontae

    2010-01-01

    Asymptotically flat wormhole solutions are found in the deformed Ho\\v{r}ava-Lifshitz gravity. It turns out that higher curvature terms can not play the role of exotic matters which are crucial to form a traversable wormhole, and external exotic sources are still needed. In particular, the exotic matter behaves like phantom energy if Kehagias-Sfetsos vacuum is considered outside the wormhole. Interestingly, the spherically symmetric setting makes the matter and the higher curvature contributio...

  5. Disruption of Tight Junctions during Traversal of the Respiratory Epithelium by Burkholderia cenocepacia

    OpenAIRE

    Kim, Jason Y.; Sajjan, Umadevi S.; Krasan, Graham P.; LiPuma, John J.

    2005-01-01

    Burkholderia cenocepacia is an opportunistic bacterial species capable of causing life-threatening respiratory tract infection in persons with cystic fibrosis (CF). Unlike most other pathogens in CF, which typically remain confined to the endobronchial spaces, B. cenocepacia can traverse airway epithelium to cause bacteremia and sepsis. The mechanisms by which this occurs, however, are unknown. We examined the transmigration of B. cenocepacia through polarized respiratory epithelium. Represen...

  6. Elitism Levels Traverse Mechanism For The Derivation of Upper Bounds on Unimodal Functions

    CERN Document Server

    Ter-Sarkisov, Aram

    2012-01-01

    In this article we present an elitism levels traverse mechanism that we designed to find bounds on population-based Evolutionary algorithms solving unimodal functions. We prove its efficiency theoretically and test it on OneMax function deriving bounds c{\\mu}n log n - O({\\mu} n). This analysis can be generalized to any similar algorithm using variants of tournament selection and genetic operators that flip or swap only 1 bit in each string.

  7. Comprehensive Study on the Estimation of the Variance Components of Traverse Nets

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    This paper advances a new simplified formula for estimating variance components ,sums up the basic law to calculate the weights of observed values and a circulation method using the increaments of weights when estimating the variance components of traverse nets,advances the charicteristic roots method to estimate the variance components of traveres nets and presents a practical method to make two real and symmetric matrices two diagonal ones.

  8. GRAPHITE: An Extensible Graph Traversal Framework for Relational Database Management Systems

    OpenAIRE

    Paradies, Marcus; Lehner, Wolfgang; Bornhoevd, Christof

    2014-01-01

    Graph traversals are a basic but fundamental ingredient for a variety of graph algorithms and graph-oriented queries. To achieve the best possible query performance, they need to be implemented at the core of a database management system that aims at storing, manipulating, and querying graph data. Increasingly, modern business applications demand native graph query and processing capabilities for enterprise-critical operations on data stored in relational database management systems. In this ...

  9. Microbial methanogenesis in the sulfate-reducing zone of surface sediments traversing the Peruvian margin

    OpenAIRE

    Maltby, J; Sommer, S; Dale, A. W.; T. Treude

    2015-01-01

    We studied the concurrence of methanogenesis and sulfate reduction in surface sediments (0–25 cm below sea floor, cmbsf) at six stations (70, 145, 253, 407, 770 and 1024 m) along the Peruvian margin (12° S). This oceanographic region is characterized by high carbon export to the seafloor, creating an extensive oxygen minimum zone (OMZ) on the shelf, both factors that could favor surface methanogenesis. Sediments sampled along the depth transect traversed are...

  10. Dynamics of beta and proliferating cell nuclear antigen sliding clamps in traversing DNA secondary structure.

    Science.gov (United States)

    Yao, N; Hurwitz, J; O'Donnell, M

    2000-01-14

    Chromosomal replicases of cellular organisms utilize a ring shaped protein that encircles DNA as a mobile tether for high processivity in DNA synthesis. These "sliding clamps" have sufficiently large linear diameters to encircle duplex DNA and are perhaps even large enough to slide over certain DNA secondary structural elements. This report examines the Escherichia coli beta and human proliferating cell nuclear antigen clamps for their ability to slide over various DNA secondary structures. The results show that these clamps are capable of traversing a 13-nucleotide ssDNA loop, a 4-base pair stem-loop, a 4-nucleotide 5' tail, and a 15-mer bubble within the duplex. However, upon increasing the size of these structures (20-nucleotide loop, 12-base pair stem-loop, 28-nucleotide 5' tail, and 20-nucleotide bubble) the sliding motion of the beta and proliferating cell nuclear antigen over these elements is halted. Studies of the E. coli replicase, DNA polymerase III holoenzyme, in chain elongation with the beta clamp demonstrate that upon encounter with an oligonucleotide annealed in its path, it traverses the duplex and resumes synthesis on the 3' terminus of the oligonucleotide. This sliding and resumption of synthesis occurs even when the oligonucleotide contains a secondary structure element, provided the beta clamp can traverse the structure. However, upon encounter with a downstream oligonucleotide containing a large internal secondary structure, the holoenzyme clears the obstacle by strand displacing the oligonucleotide from the template. Implications of these protein dynamics to DNA transactions are discussed. PMID:10625694

  11. Fate of the first traversible wormhole: Black-hole collapse or inflationary expansion

    International Nuclear Information System (INIS)

    We study numerically the stability of the first Morris-Thorne traversible wormhole, shown previously by Ellis to be a solution for a massless ghost Klein-Gordon field. Our code uses a dual-null formulation for spherically symmetric space-time integration, and the numerical range covers both universes connected by the wormhole. We observe that the wormhole is unstable against Gaussian pulses in either exotic or normal massless Klein-Gordon fields. The wormhole throat suffers a bifurcation of horizons and either explodes to form an inflationary universe or collapses to a black hole if the total input energy, is, respectively, negative or positive. As the perturbations become small in total energy, there is evidence for critical solutions with a certain black-hole mass or Hubble constant. The collapse time is related to the initial energy with an apparently universal critical exponent. For normal matter, such as a traveller traversing the wormhole, collapse to a black hole always results. However, carefully balanced additional ghost radiation can maintain the wormhole for a limited time. The black-hole formation from a traversible wormhole confirms the recently proposed duality between them. The inflationary case provides a mechanism for inflating, to macroscopic size, a Planck-sized wormhole formed in space-time foam

  12. Heart Disease and African Americans

    Science.gov (United States)

    ... Minority Population Profiles > Black/African American > Heart Disease Heart Disease and African Americans Although African American adults are ... were 30 percent more likely to die from heart disease than non-Hispanic whites. African American women are ...

  13. Infant Mortality and African Americans

    Science.gov (United States)

    ... African American > Infant Heath & Mortality Infant Mortality and African Americans African Americans have 2.2 times the infant mortality rate ... birthweight as compared to non-Hispanic white infants. African Americans had almost twice the sudden infant death syndrome ...

  14. Competências de ensino: um estudo com professoras no contexto do jogo Traverse Teaching competences: a study with teachers in a Traverse game context

    Directory of Open Access Journals (Sweden)

    Meire Andersan Fiorot

    2007-12-01

    Full Text Available Esta pesquisa teve por objetivo verificar o modo de ensinar de professoras em um contexto de jogo de regras. Participaram da pesquisa quatro professoras da quarta série do ensino fundamental de uma escola particular do Espírito Santo. O procedimento de pesquisa foi organizado com uma situação de ensino, formada pelas fases de instrução e de experimentação, utilizando o jogo Traverse. O estudo contou com a colaboração de quatro crianças. Os resultados obtidos permitiram verificar que houve um predomínio de procedimentos com características negativas sendo identificadas algumas dificuldades apresentadas pelas professoras, tanto no momento de instruir quanto no de mediar. Diante dessa constatação, sugerimos uma reflexão mais ampla sobre o que têm sido oferecido aos professores em seus processos de formação docente e de formação continuada, considerando que a profissionalização requer um trabalho de tomada de consciência sobre os próprios processos de aprendizagem.This research aimed at checking the way teachers teach in a rule game context. The participants were four teachers of the fourth grade of a private primary school in Espírito Santo State. The procedure of the research was organized within a teaching situation, build up by the stages of instruction and experiment using the Traverse game. The study had the additional participation of four children. The results showed that there was predominance of procedures with negative characteristics. The teachers presented some difficulties either at the time of instruction or mediation. Based on this observation, we suggest a wider reflection about what is being offered to the teachers in their graduation process, considering that the professionalization requires awareness of one's own learning processes.

  15. On the flow velocity of the ice sheet along the traverse route from Syowa to Mizuho Station, East Antarctica

    OpenAIRE

    SHIBUYA,Kazuo/ITO,Kiyoshi

    1983-01-01

    The 21st Japanese Antarctic Research Expedition (JARE-21,1979-1981) made several explosion seismic experiments by installing seismic stations along the S-H-Z route from Syowa to Mizuho Stations, on which JARE-14 (1972-1974) had made the traverse survey. Most of the seismic stations were selected to be closely located near the traverse stations, so that the position of each traverse station could be determined from that of a nearby seismic station determined by the NNSS positioning. By compari...

  16. Traverses for lunar rovers and sample return teleoperated from Earth or cislunar orbit

    Science.gov (United States)

    Kamps, Oscar; Foing, Bernard H.; Flahaut, Jessica

    2016-07-01

    Most interesting sites for exploration are near the poles of the Moon where water and other ices and volatiles could be stable in the permanent shaded regions. Several instruments on multiple orbiters have indicated the presence of hydrogen or hydration but the relation with the illumination conditions are not as clear. Which other variables are involved to trap water near the poles is not known. This ignorance makes it of high interest to do in-situ research on the Moon. ESA, NASA and other agencies are studying a teleoperated mission from cislunar orbit with Orion (eg. HERACLES international lunar exploration architecture) with the possibility of long rover traverses, and human assisted sample return. This mission concept was used for this study on a rover traverse. This study focuses on both the North as South Pole. The site selection for a traverse was based on the temperature map from Diviner. Regions of interests were made as primary selection and cover areas where the maximum temperature is lower than the sublimation temperature of CO2. Data from neutron spectrometer from the Prospector, and crater epoch according to the USGS were used to make a selection of regions of interest. These selected sites where studied on their accessibility for a rover, based on the slope map made from the LOLA elevation model. A landing site was selected based on assumptions that it should be at least one kilometre in diameter and have a slope lower than 5 degrees. The temperature difference (Tmax-Tmin from the Diviner measurements) was used select a scientifically interesting site between the landing site and destination inside a PSR. It was thought that a site with a temperature difference larger than 150K is interesting to study volatile migration processes. Eventually for the traverse planning a tool in ArcGIS was used which calculates the easiest from one location to another where the slope is used as limiting factor. We give the example study of rover traverse planning

  17. African Americans and Glaucoma

    Science.gov (United States)

    ... Involved News About Us Donate In This Section African Americans and Glaucoma email Send this article to ... glaucoma is the leading cause of blindness in African Americans. Half of those with glaucoma don't ...

  18. Diabetes in African Americans

    OpenAIRE

    Marshall, M.

    2005-01-01

    African Americans have a high risk for type 2 diabetes. Genetic traits, the prevalence of obesity, and insulin resistance all contribute to the risk of diabetes in the African American community. African Americans have a high rate of diabetic complications, because of poor glycaemic control and racial disparities in health care in the USA. African Americans with diabetes may have an atypical presentation that simulates type 1 diabetes, but then their subsequent clinical course is typical of t...

  19. Identification and Optimization of Inhibitors of Trypanosomal Cysteine Proteases: Cruzain, Rhodesain, and TbCatB

    OpenAIRE

    Mott, Bryan T.; Ferreira, Rafaela S.; Simeonov, Anton; Jadhav, Ajit; Ang, Kenny Kean-Hooi; Leister, William; Shen, Min; Silveira, Julia T.; Doyle, Patricia S; Michelle R. Arkin; McKerrow, James H.; Inglese, James; Austin, Christopher P; Thomas, Craig J.; Shoichet, Brian K.

    2010-01-01

    Trypanosoma cruzi and Trypanosoma brucei are parasites that cause Chagas’ disease and African sleeping sickness, respectively. Both parasites rely on essential cysteine proteases for survival, cruzain for T. cruzi and TbCatB/rhodesain for T. brucei. A recent quantitative high-throughput screen of cruzain identified triazine nitriles, which are known inhibitors of other cysteine proteases, as reversible inhibitors of the enzyme. Structural modifications detailed herein, including core scaffold...

  20. New organoruthenium complexes with bioactive thiosemicarbazones as co-ligands: potential anti-trypanosomal agents†

    OpenAIRE

    Demoro, Bruno; Sarniguet, Cynthia; Sánchez-Delgado, Roberto; Rossi, Miriam; Liebowitz, Daniel; Caruso, Francesco; Olea-Azar, Claudio; Moreno, Virtudes; Medeiros, Andrea; Comini, Marcelo A.; Otero, Lucía; Gambino, Dinorah

    2011-01-01

    In the search for new therapeutic tools against neglected diseases produced by trypanosomatid parasites, and particularly against African Trypanosomiasis, whose etiological agent is Trypanosoma brucei, organoruthenium compounds with bioactive nitrofuran containing thiosemicarbazones (L) as co-ligands were obtained. Four ruthenium(ii) complexes with the formula [Ru2(p-cymene)2(L)2]X2, where X = Cl or PF6, were synthesized and the crystal structures of two of them were solved by X-ray diffracti...

  1. Squalamine analogues as potential anti-trypanosomal and anti-leishmanial compounds.

    Science.gov (United States)

    Khabnadideh, S; Tan, C L; Croft, S L; Kendrick, H; Yardley, V; Gilbert, I H

    2000-06-01

    This paper concerns the synthesis of various simplified analogues of the novel anti-microbial agent, squalamine. The compounds were then investigated for activity against Trypanosoma brucei, the causative agent of African trypanosomiasis, Trypanosoma cruzi, the causative agent of Chagas disease and Leishmania donovani, the causative agent of visceral leishmaniasis. Several compounds showed in vitro activity, especially against T. brucei and L. donovani. However, one compound showed poor in vivo activity. PMID:10866389

  2. African American Suicide

    Science.gov (United States)

    African American Suicide Fact Sheet Based on 2012 Data (2014) Overview • In 2012, 2,357 African Americans completed suicide in the U.S. Of these, ... 46 per 100,000. • The suicide rate for African Americans ages 10-19 was 2.98 per ...

  3. Kevin Traverse-Healy: kommunikatsiooni eesmärk on muuta käitumist / intervjueerinud Annela Laaneots

    Index Scriptorium Estoniae

    Traverse-Healy, Kevin

    2013-01-01

    Intervjuu strateegianõuniku ja rahvusvaheliselt tuntud kommunikatsioonieksperdi Kevin Traverse-Healyga, kes peab eduka kommunikatsioonijuhi töös oluliseks luua õige kommunikatsioon, mille eesmärgiks on sihtrühma käitumise muutus

  4. Design and implementation of a three axis digitally controlled traverse system for flow surveys in a drying chamber

    Directory of Open Access Journals (Sweden)

    Achilleas Bardakas

    2014-06-01

    Full Text Available The current paper describes the design and development of a pc-controlled three axis traverse system that aims to serve extensive velocity and temperature measurements into the drying chamber of a laboratory scale convective dryer. The traversing gear design has been conducted based on the convective dryer’s specific experimental requirements and limitations. The fabricated traversing gear uses a trapezoidal lead screw-nut assembly supported by linear ball bearings, coupled with bipolar stepper motors for positioning in three dimensional spaces. A custom drive system solution was selected for achieving accurate motor control, paired with computer software developed using the LabVIEW® graphical programming environment. The functionality of the traversing system was experimentally verified by testing mechanical and electronic assemblies, but also by determining the per axis positioning error. Keywords: Fluid Flow Measurement, Digital Control, Motion Control, Displacement Control, Electromechanical Devices.

  5. In vitro activity of 2-pyridinecarboxylic acid against trypanosomes of the subgenus Schizotrypanum isolated from the bat Phyllostomus hastatus - doi: 10.4025/actascibiolsci.v33i4.6482 In vitro activity of 2-pyridinecarboxylic acid against trypanosomes of the subgenus Schizotrypanum isolated from the bat Phyllostomus hastatus - doi: 10.4025/actascibiolsci.v33i4.6482

    Directory of Open Access Journals (Sweden)

    Sueli Fumie Yamada-Ogatta

    2011-09-01

    Full Text Available The effect of 2-pyridinecarboxylic acid (picolinic acid on trypanosomes of the subgenus Schizotrypanum isolated from the bat Phyllostomus hastatus was determined in this study. Picolinic acid, at 50 µg mL-1, inhibited epimastigote growth by 99% after 12 days incubation. In addition, trypomastigote motility decreased by 50% after 6h and completely after 24h in the presence of 50 µg mL-1 picolinic acid. The 50% cytotoxic concentration on HEp-2 cell line was 275 µg mL-1 after 4 days incubation. Altogether, these results indicate higher toxicity against trypanosomes. The inhibitory effect of picolinic acid on epimastigote growth can be partially reversed by nicotinic acid and L-tryptophan, suggesting a competitive inhibition. Furthermore, two anti-Trypanosoma (Schizotrypanum cruzi drugs were also evaluated with regard to bat trypanosome growth. Benznidazole, at 50 µg mL-1, inhibited epimastigote growth by 90% after 12 days incubation. Nifurtimox, at the same concentration, caused 96% growth inhibition after four days incubation. Corroborating a previous study, bat trypanosomes are a good model for screening new trypanocidal compounds. Moreover, they can be used to study many biological processes common to human pathogenic trypanosomatids.The effect of 2-pyridinecarboxylic acid (picolinic acid on trypanosomes of the subgenus Schizotrypanum isolated from the bat Phyllostomus hastatus was determined in this study. Picolinic acid, at 50 µg mL-1, inhibited epimastigote growth by 99% after 12 days incubation. In addition, trypomastigote motility decreased by 50% after 6h and completely after 24h in the presence of 50 µg mL-1 picolinic acid. The 50% cytotoxic concentration on HEp-2 cell line was 275 µg mL-1 after 4 days incubation. Altogether, these results indicate higher toxicity against trypanosomes. The inhibitory effect of picolinic acid on epimastigote growth can be partially reversed by nicotinic acid and L-tryptophan, suggesting a

  6. Characteristics of pebble- and cobble-sized clasts along the Curiosity rover traverse from Bradbury Landing to Rocknest

    OpenAIRE

    Yingst, R.A.; Kah, L. C.; Palucis, M.; Williams, R. M. E.; Garvin, J.; Bridges, J. C.; Bridges, N.; Deen, R. G.; Farmer, J.; Gasnault, O.; Goetz, W.; Hamilton, V. E.; Hipkin, V.; Jensen, J.K.; King, P. L.

    2013-01-01

    We have assessed the characteristics of clasts along Curiosity's traverse to shed light on the processes important in the genesis, modification, and transportation of surface materials. Pebble- to cobble-sized clasts at Bradbury Landing, and subsequently along Curiosity's traverse to Yellowknife Bay, reflect a mixing of two end-member transport mechanisms. The general clast population likely represents material deposited via impact processes, including meteorite fragments, ejecta from distant...

  7. Traversing and labeling interconnected vascular tree structures from 3D medical images

    Science.gov (United States)

    O'Dell, Walter G.; Govindarajan, Sindhuja Tirumalai; Salgia, Ankit; Hegde, Satyanarayan; Prabhakaran, Sreekala; Finol, Ender A.; White, R. James

    2014-03-01

    Purpose: Detailed characterization of pulmonary vascular anatomy has important applications for the diagnosis and management of a variety of vascular diseases. Prior efforts have emphasized using vessel segmentation to gather information on the number or branches, number of bifurcations, and branch length and volume, but accurate traversal of the vessel tree to identify and repair erroneous interconnections between adjacent branches and neighboring tree structures has not been carefully considered. In this study, we endeavor to develop and implement a successful approach to distinguishing and characterizing individual vascular trees from among a complex intermingling of trees. Methods: We developed strategies and parameters in which the algorithm identifies and repairs false branch inter-tree and intra-tree connections to traverse complicated vessel trees. A series of two-dimensional (2D) virtual datasets with a variety of interconnections were constructed for development, testing, and validation. To demonstrate the approach, a series of real 3D computed tomography (CT) lung datasets were obtained, including that of an anthropomorphic chest phantom; an adult human chest CT; a pediatric patient chest CT; and a micro-CT of an excised rat lung preparation. Results: Our method was correct in all 2D virtual test datasets. For each real 3D CT dataset, the resulting simulated vessel tree structures faithfully depicted the vessel tree structures that were originally extracted from the corresponding lung CT scans. Conclusion: We have developed a comprehensive strategy for traversing and labeling interconnected vascular trees and successfully implemented its application to pulmonary vessels observed using 3D CT images of the chest.

  8. Cockroaches traverse crevices, crawl rapidly in confined spaces, and inspire a soft, legged robot.

    Science.gov (United States)

    Jayaram, Kaushik; Full, Robert J

    2016-02-23

    Jointed exoskeletons permit rapid appendage-driven locomotion but retain the soft-bodied, shape-changing ability to explore confined environments. We challenged cockroaches with horizontal crevices smaller than a quarter of their standing body height. Cockroaches rapidly traversed crevices in 300-800 ms by compressing their body 40-60%. High-speed videography revealed crevice negotiation to be a complex, discontinuous maneuver. After traversing horizontal crevices to enter a vertically confined space, cockroaches crawled at velocities approaching 60 cm⋅s(-1), despite body compression and postural changes. Running velocity, stride length, and stride period only decreased at the smallest crevice height (4 mm), whereas slipping and the probability of zigzag paths increased. To explain confined-space running performance limits, we altered ceiling and ground friction. Increased ceiling friction decreased velocity by decreasing stride length and increasing slipping. Increased ground friction resulted in velocity and stride length attaining a maximum at intermediate friction levels. These data support a model of an unexplored mode of locomotion--"body-friction legged crawling" with body drag, friction-dominated leg thrust, but no media flow as in air, water, or sand. To define the limits of body compression in confined spaces, we conducted dynamic compressive cycle tests on living animals. Exoskeletal strength allowed cockroaches to withstand forces 300 times body weight when traversing the smallest crevices and up to nearly 900 times body weight without injury. Cockroach exoskeletons provided biological inspiration for the manufacture of an origami-style, soft, legged robot that can locomote rapidly in both open and confined spaces. PMID:26858443

  9. A Study of Parallels Between Antarctica South Pole Traverse Equipment and Lunar/Mars Surface Systems

    Science.gov (United States)

    Mueller, Robert P.; Hoffman, Stephen, J.; Thur, Paul

    2010-01-01

    The parallels between an actual Antarctica South Pole re-supply traverse conducted by the National Science Foundation (NSF) Office of Polar Programs in 2009 have been studied with respect to the latest mission architecture concepts being generated by the United States National Aeronautics and Space Administration (NASA) for lunar and Mars surface systems scenarios. The challenges faced by both endeavors are similar since they must both deliver equipment and supplies to support operations in an extreme environment with little margin for error in order to be successful. By carefully and closely monitoring the manifesting and operational support equipment lists which will enable this South Pole traverse, functional areas have been identified. The equipment required to support these functions will be listed with relevant properties such as mass, volume, spare parts and maintenance schedules. This equipment will be compared to space systems currently in use and projected to be required to support equivalent and parallel functions in Lunar and Mars missions in order to provide a level of realistic benchmarking. Space operations have historically required significant amounts of support equipment and tools to operate and maintain the space systems that are the primary focus of the mission. By gaining insight and expertise in Antarctic South Pole traverses, space missions can use the experience gained over the last half century of Antarctic operations in order to design for operations, maintenance, dual use, robustness and safety which will result in a more cost effective, user friendly, and lower risk surface system on the Moon and Mars. It is anticipated that the U.S Antarctic Program (USAP) will also realize benefits for this interaction with NASA in at least two areas: an understanding of how NASA plans and carries out its missions and possible improved efficiency through factors such as weight savings, alternative technologies, or modifications in training and

  10. Análise do processo de tomada de consciência de professoras por meio do jogo Traverse Analysis of the teachers awareness process through Traverse game

    Directory of Open Access Journals (Sweden)

    Meire Andersan Fiorot

    2008-12-01

    Full Text Available Esta pesquisa teve por objetivo investigar, em uma perspectiva microgenética, o processo de tomada de consciência de quatro professoras, por meio de um jogo de regras. O procedimento de pesquisa foi organizado em duas fases: de instrução e de experimentação. Em ambas, foi utilizado o jogo Traverse. Vários questionamentos foram propostos de modo que as professoras pudessem refletir sobre as situações vividas no jogo. Os resultados constataram uma evolução nos níveis de compreensão do sistema lógico contido no jogo, com a existência de momentos intermediários que indicaram uma tomada de consciência parcial da ação. A principal dificuldade apresentada, nesse processo, foi a compreensão da dialética intersistêmica existente no jogo. Diante dessa constatação, sugerimos uma reflexão mais ampla sobre os contextos de aprendizagem que têm sido oferecidos aos professores em seus processos de formação, considerando que a profissionalização requer um trabalho de tomada de consciência sobre os próprios processos de aprendizagem.This research aims at investigating, in microgenetics perspective, the awareness process of four teachers through a rules game. The research procedure was organized into two stages: the instruction and experiment. In both of them the Traverse game was used. A lot of questions were offered so that the teachers could make reflections about the situations experienced in the game. The results showed an evolution in the comprehension levels of the logical system of the game, with intermediate moments that indicated a parcial awareness of the action. The main difficulty in this process was the comprehension of the intersystemic dialectics of the game. Faced with this evidence, we suggest a deeper reflection about the learning contexts wich have been offered to the teachers in their instructional processes, considering that ones's profissionalization requires a careful awareness process about his particular

  11. An overview of South African psychology.

    Science.gov (United States)

    Cooper, Saths; Nicholas, Lionel

    2012-01-01

    This overview of psychology in South Africa presents a concise and historical account of its science and practice, from its early origins in the late nineteenth century to the present, and traces seminal influences on the discipline. It is a review of how psychology in South Africa developed over more than a century to become one of the most popular subjects in universities and an established and recognized profession, whose members play a variety of roles in the South African polity and larger society. The impact that apartheid racism had on key aspects of psychology's development is traversed, and the influences that previous ruling party politics had on professional psychological organizations are delineated. The unification of psychology under the Psychological Society of South Africa, a few months before the advent of democracy in South Africa, is explicated. The protection of the title of psychologist in law and certain other changes in the legislative environment, enabling a greater role for psychologists, are reported. The primary research sites for psychology and its funding and the main university psychology programs are described, as are the requirements for registration and licensure. The genesis and the importance of the work of internationally acclaimed South African psychologists, such as J. Wolpe and A. A. Lazarus, are contextualized. With the increased participation of progressive black psychologists in leadership and research in the past two decades, a transformed psychology has the potential to play a significant role in addressing human issues confronting South Africa. PMID:22432681

  12. Radiometric traverse along the Yukon River from Fort Yukon to Ruby, Alaska, 1949

    Science.gov (United States)

    White, Max G.; Stevens, John M.; Matzko, John J.

    1956-01-01

    In 1949, a radiometric traverse was made of rocks exposed along the banks of and near the Yukon River about Fort Yukon to Ruby, Alaska. Granitic rocks of Tertiary age and of Devonian or Carboniferous age and sandstone beds of Cretaceous age gave the highest readings obtained in the field. Other rock types examined were greenstone of Devonian or Carboniferous age and metamorphic rocks of Devonian and pre-Devonian age, sedimentary rocks, and liginite of Tertiary age, and alluvial deposits of Quaternary age. The most radioactive sample, from Melozitna River canyon, contained only 0.017 percent equivalent uranium.

  13. Predicting Long-Range Traversability from Short-Range Stereo-Derived Geometry

    Science.gov (United States)

    Turmon, Michael; Tang, Benyang; Howard, Andrew; Brjaracharya, Max

    2010-01-01

    Based only on its appearance in imagery, this program uses close-range 3D terrain analysis to produce training data sufficient to estimate the traversability of terrain beyond 3D sensing range. This approach is called learning from stereo (LFS). In effect, the software transfers knowledge from middle distances, where 3D geometry provides training cues, into the far field where only appearance is available. This is a viable approach because the same obstacle classes, and sometimes the same obstacles, are typically present in the mid-field and the farfield. Learning thus extends the effective look-ahead distance of the sensors.

  14. Traversable terrain classification for outdoor autonomous robots using single 2D laser scans

    DEFF Research Database (Denmark)

    Andersen, Jens Christian; Blas, Morten Rufus; Andersen, Nils Axel; Ravn, Ole; Blanke, Mogens

    2006-01-01

    Interpreting laser data to allow autonomous robot navigation on paved as well as dirt roads using a fixed angle 2D laser scanner is a daunting task. This paper introduces an algorithm for terrain classification that fuses seven distinctly different classifiers: raw height, roughness, step size......, curvature, slope, width and invalid data. These are then used to extract road borders, traversable terrain and identify obstacles. Experimental results are shown and discussed. The results were obtained using a DTU developed mobile robot, and the autonomous tests were conducted in a national park...

  15. Microbial methanogenesis in the sulfate-reducing zone of surface sediments traversing the Peruvian margin

    OpenAIRE

    Maltby, J; Sommer, S; Dale, A. W.; T. Treude

    2016-01-01

    We studied the concurrence of methanogenesis and sulfate reduction in surface sediments (0–25 cm below sea floor) at six stations (70, 145, 253, 407, 990 and 1024 m) along the Peruvian margin (12° S). This oceanographic region is characterized by high carbon export to the seafloor creating an extensive oxygen minimum zone (OMZ) on the shelf, both factors that could favor surface methanogenesis. Sediments sampled along the depth transect traversed areas of anoxic and oxic ...

  16. Surveillance of tsetse fly and cattle populations for trypanosomes in the BICOT area during the sterile insect technique control programme

    International Nuclear Information System (INIS)

    Between March 1984 and March 1988 animal surveys for bovine trypanosomiasis were conducted periodically on resident herds in the Biological Control of Tsetse (BICOT) Project area in Lafia, Plateau State, Nigeria, using standard detection methods. Over a specified period sentinel herds were also examined in selected locations within the project area. Fly trapping and dissection were similarly used for trypanosome screening of wild and released flies. In both resident and sentinel herds, infections were detected consistently, showing the persistence of the disease throughout the period of survey. Fly trapping and dissection revealed that the target species, Glossina palpalis palpalis, was effectively eliminated from the control zone, or may be persisting only at an undetectable level. However, G. tachinoides was present in most of these areas and may therefore have been responsible for the persistence of infection. Infection among resident herds could have also been due to their migratory activities, taking them to areas outside the control project. (author). 10 refs, 9 tabs

  17. In vitro-in vivo studies on anti-trypanosomal potentials of Zapoteca portoricensis

    Institute of Scientific and Technical Information of China (English)

    Nwodo NJ; Omeje EO; Brun R

    2009-01-01

    Objective:Aqueous extracts of Zapoteca portoricensis are used traditionally as antidiarrhea agent and in the treatment of diverse gastrointestinal disorders here in Nigeria specifically,the southern part.Similarly,the a-queous extract of the plant is also used traditionally as anticonvulsant,antispasmodic and in the treatment of tonsillitis.Recently too,the anti-inflammatory and antimicrobial activities of the methanol extracts of the root of Zapoteca portoricensis was reported.In this research,we are set to investigate the trypanocidal activity of Zapoteca portoricensis.Methods:The methanol extract of the root of Zapoteca portoricensis was investigated for both in vitro and in vivo trypanocidal activity following established models.In summary,phytochemical analy-sis was carried out on both the crude powdered root and on the methanol extract following standard procedures. The oral acute toxicity test (LD50 )of the crude methanol extract was determined according to the method de-scribed by Lorke (1983).Albino mice (17g-21g)of either sex were used.The methanol extract was suspen-ded in 3 % v /v tween 85 and administered orally at doses of 10 mg/kg,100 mg/kg and 1 000 mg/kg to three groups of mice (n =3).The animals were observed for 24 hours.Based on the result obtained in this initial test,doses of 4 mg/kg,6 mg/kg,and 8 mg/kg were administered to three different mice.The LD50 was calcu-lated as the geometric mean of the lowest dose killing a mouse and the highest dose showing no death.The in-vivo /in-vitro anti-trypanosomal evaluations were carried out in experimental animals and tissue cell culture re-spectively.Results:The result of the in vitro studies shows the inhibitive concentration-50(IC-50)against Trypanosoma brucei rhodesiense (T.b.rhodesiense)to be 0.372 mg/kg,while the control drug melarsoprol was 0.006 mg/kg.On Trypanosoma brucei brucei (T .cruzi),the IC-50 is 6.42 mg/kg against 0.87 of the ref-erence drug Benznidazole.The cyctotoxicity on L-6 cells

  18. Time-Domain Pure-state Polarization Analysis of Surface Waves Traversing California

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J; Walter, W R; Lay, T; Wu, R

    2003-11-04

    A time-domain pure-state polarization analysis method is used to characterize surface waves traversing California parallel to the plate boundary. The method is applied to data recorded at four broadband stations in California from twenty-six large, shallow earthquakes which occurred since 1988, yielding polarization parameters such as the ellipticity, Euler angles, instantaneous periods, and wave incident azimuths. The earthquakes are located along the circum-Pacific margin and the ray paths cluster into two groups, with great-circle paths connecting stations MHC and PAS or CMB and GSC. The first path (MHC-PAS) is in the vicinity of the San Andreas Fault System (SAFS), and the second (CMB-GSC) traverses the Sierra Nevada Batholith parallel to and east of the SAFS. Both Rayleigh and Love wave data show refractions due to lateral velocity heterogeneities under the path, indicating that accurate phase velocity and attenuation analysis requires array measurements. The Rayleigh waves are strongly affected by low velocity anomalies beneath Central California, with ray paths bending eastward as waves travel toward the south, while Love waves are less affected, providing observables to constrain the depth extent of the anomalies. Strong lateral gradients in the lithospheric structure between the continent and the ocean are the likely cause of the path deflections.

  19. Traversable wormholes satisfying the weak energy condition in third-order Lovelock gravity

    Science.gov (United States)

    Zangeneh, Mahdi Kord; Lobo, Francisco S. N.; Dehghani, Mohammad Hossein

    2015-12-01

    In this paper, we consider third-order Lovelock gravity with a cosmological constant term in an n -dimensional spacetime M4×Kn -4, where Kn -4 is a constant curvature space. We decompose the equations of motion to four and higher dimensional ones and find wormhole solutions by considering a vacuum Kn -4 space. Applying the latter constraint, we determine the second- and third-order Lovelock coefficients and the cosmological constant in terms of specific parameters of the model, such as the size of the extra dimensions. Using the obtained Lovelock coefficients and Λ , we obtain the four-dimensional matter distribution threading the wormhole. Furthermore, by considering the zero tidal force case and a specific equation of state, given by ρ =(γ p -τ )/[ω (1 +γ )], we find the exact solution for the shape function which represents both asymptotically flat and nonflat wormhole solutions. We show explicitly that these wormhole solutions in addition to traversibility satisfy the energy conditions for suitable choices of parameters and that the existence of a limited spherically symmetric traversable wormhole with normal matter in a four-dimensional spacetime implies a negative effective cosmological constant.

  20. Problems of Construction of Black Holes and Traversed Wormholes in Various Theories of Gravity

    Science.gov (United States)

    Karbanovski, Valeri; Kairov, Taimuraz.; Melehina, Olga

    In the framework of general relativity found new vacuum solutions [1,2] for the spherically symmetric non-static metrics as a constant source ("dynamic analog" gravitational radius), and a source in the form of time-dependent functions. In the latter case, the conditions for a smooth cross-linking with the original static metric. Within Post-Einstein theory of gravitation (PETG, [3]), is consider the variant with zero scalar curvature of space-time is considered. Found external solutions for spherically symmetric objects that allow a smooth stitching at distances slightly exceeding the gravitational radius of the source. We also show that in the studied approach the traversable vacuum wormholes can not be realized. In the theory of gravity with vacuum polarization (TGVP, [4]) built vacuum static spherically symmetric nonsingular solutions. At this the "polarization effects" appear only under the gravitational radius of the source. Also obtained metric describing the vacuum traversable wormhole. References begin{enumerate} Karbanovski V.V. et. al. - JETP, 2012, Vol. 115, No. 2, pp. 208-211. Karbanovski V.V. et. al. - JETP, 2012, Vol. 115, No. 4, pp. 733. Karbanovski V.V. et. al. - Class. Quantum Grav., 2012, Vol. 29, No. 6, 065007. Karbanovski V.V. et. al. - Acta Phys. Pol. B, 2011, Vol. 42, No.1, p. 171.

  1. African Otter Workshop

    OpenAIRE

    Jan Reed-Smith; Hughes Akpona; Grace Yoxon

    2016-01-01

    All concerned thought this was an excellent workshop with important progress made towards creating a viable beginning of an African Otter Network. There is a long road ahead but the 2015 African Otter Workshop is a start on developing range country partners, activists and researchers as well as collaborating on issue identification and resolution which will assist in preserving at least some refugia for Africa’s otters. A list of actions was agreed on, including the creation of an African Ott...

  2. African and non-African admixture components in African Americans and an African Caribbean population.

    Science.gov (United States)

    Murray, Tanda; Beaty, Terri H; Mathias, Rasika A; Rafaels, Nicholas; Grant, Audrey Virginia; Faruque, Mezbah U; Watson, Harold R; Ruczinski, Ingo; Dunston, Georgia M; Barnes, Kathleen C

    2010-09-01

    Admixture is a potential source of confounding in genetic association studies, so it becomes important to detect and estimate admixture in a sample of unrelated individuals. Populations of African descent in the US and the Caribbean share similar historical backgrounds but the distributions of African admixture may differ. We selected 416 ancestry informative markers (AIMs) to estimate and compare admixture proportions using STRUCTURE in 906 unrelated African Americans (AAs) and 294 Barbadians (ACs) from a study of asthma. This analysis showed AAs on average were 72.5% African, 19.6% European and 8% Asian, while ACs were 77.4% African, 15.9% European, and 6.7% Asian which were significantly different. A principal components analysis based on these AIMs yielded one primary eigenvector that explained 54.04% of the variation and captured a gradient from West African to European admixture. This principal component was highly correlated with African vs. European ancestry as estimated by STRUCTURE (r(2)=0.992, r(2)=0.912, respectively). To investigate other African contributions to African American and Barbadian admixture, we performed PCA on approximately 14,000 (14k) genome-wide SNPs in AAs, ACs, Yorubans, Luhya and Maasai African groups, and estimated genetic distances (F(ST)). We found AAs and ACs were closest genetically (F(ST)=0.008), and both were closer to the Yorubans than the other East African populations. In our sample of individuals of African descent, approximately 400 well-defined AIMs were just as good for detecting substructure as approximately 14,000 random SNPs drawn from a genome-wide panel of markers. PMID:20717976

  3. Co-visualization of DNA damage and ion traversals in live mammalian cells using a fluorescent nuclear track detector

    International Nuclear Information System (INIS)

    The geometric locations of ion traversals in mammalian cells constitute important information in the study of heavy ion-induced biological effect. Single ion traversal through a cellular nucleus produces complex and massive DNA damage at a nanometer level, leading to cell inactivation, mutations and transformation. We present a novel approach that uses a fluorescent nuclear track detector (FNTD) for the simultaneous detection of the geometrical images of ion traversals and DNA damage in single cells using confocal microscopy. HT1080 or HT1080–53BP1-GFP cells were cultured on the surface of a FNTD and exposed to 5.1-MeV/n neon ions. The positions of the ion traversals were obtained as fluorescent images of a FNTD. Localized DNA damage in cells was identified as fluorescent spots of γ-H2AX or 53BP1-GFP. These track images and images of damaged DNA were obtained in a short time using a confocal laser scanning microscope. The geometrical distribution of DNA damage indicated by fluorescent γ-H2AX spots in fixed cells or fluorescent 53BP1-GFP spots in living cells was found to correlate well with the distribution of the ion traversals. This method will be useful for evaluating the number of ion hits on individual cells, not only for micro-beam but also for random-beam experiments. (author)

  4. Testing promoter activity in the trypanosome genome: isolation of a metacyclic-type VSG promoter, and unexpected insights into RNA polymerase II transcription.

    Science.gov (United States)

    McAndrew, M; Graham, S; Hartmann, C; Clayton, C

    1998-09-01

    In trypanosomes, most genes are arranged in polycistronic transcription units. Individual mRNAs are generated by 5'-trans splicing and 3' polyadenylation. Remarkably, no regulation of RNA polymerase II transcription has been detected although many RNAs are differentially expressed during kinetoplastid life cycles. Demonstration of specific class II promoters is complicated by the difficulty in distinguishing between genuine promoter activity and stimulation of trans splicing. Using vectors that were designed to allow the detection of low promoter activities in a transcriptionally silent chromosomal context, we isolated a novel trypanosome RNA polymerase I promoter. We were however unable to detect class II promoter activity in any tested DNA fragment. We also integrated genes which were preceded by a T3 promoter into the genome of cells expressing bacteriophage T3 polymerase: surprisingly, transcription was alpha-amanitin sensitive. One possible interpretation of these results is that in trypanosomes, RNA polymerase II initiation is favored by genomic accessibility and double-strand melting. PMID:9709032

  5. Study on Key Techniques for Multi-scale Expression of Laneway Traverse Data in MGIS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The multi-scale expression of enormously complicated laneway data requires differentiation of both contents and the way the contents are expressed.To accomplish multi-scale expression laneway data must support multi-scale transformation and have consistent topological relationships.Although the laneway data generated by traverse surveying is non-scale data it is still impossible to construct a multi-scale spatial database directly from it.In this paper an algorithm is presented to first calculate the laneway mid-line to support multi-scale transformation; then to express topological relationships arising from the data structure; and, finally, a laneway spatial database is built and multi-scale expression is achieved using components GIS-SuperMap Objects.The research result is of great significance for improving the efficiency of laneway data storage and updating, for ensuring consistency of laneway data expression and for extending the potential value of a mine spatial database.

  6. A New MANET Wormhole Detection Algorithm Based on Traversal Time and Hop Count Analysis

    Directory of Open Access Journals (Sweden)

    Göran Pulkkis

    2011-11-01

    Full Text Available As demand increases for ubiquitous network facilities, infrastructure-less and self-configuring systems like Mobile Ad hoc Networks (MANET are gaining popularity. MANET routing security however, is one of the most significant challenges to wide scale adoption, with wormhole attacks being an especially severe MANET routing threat. This is because wormholes are able to disrupt a major component of network traffic, while concomitantly being extremely difficult to detect. This paper introduces a new wormhole detection paradigm based upon Traversal Time and Hop Count Analysis (TTHCA, which in comparison to existing algorithms, consistently affords superior detection performance, allied with low false positive rates for all wormhole variants. Simulation results confirm that the TTHCA model exhibits robust wormhole route detection in various network scenarios, while incurring only a small network overhead. This feature makes TTHCA an attractive choice for MANET environments which generally comprise devices, such as wireless sensors, which possess a limited processing capability.

  7. Identifying time measurement tampering in the traversal time and hop count analysis (TTHCA) wormhole detection algorithm.

    Science.gov (United States)

    Karlsson, Jonny; Dooley, Laurence S; Pulkkis, Göran

    2013-01-01

    Traversal time and hop count analysis (TTHCA) is a recent wormhole detection algorithm for mobile ad hoc networks (MANET) which provides enhanced detection performance against all wormhole attack variants and network types. TTHCA involves each node measuring the processing time of routing packets during the route discovery process and then delivering the measurements to the source node. In a participation mode (PM) wormhole where malicious nodes appear in the routing tables as legitimate nodes, the time measurements can potentially be altered so preventing TTHCA from successfully detecting the wormhole. This paper analyses the prevailing conditions for time tampering attacks to succeed for PM wormholes, before introducing an extension to the TTHCA detection algorithm called ∆T Vector which is designed to identify time tampering, while preserving low false positive rates. Simulation results confirm that the ∆T Vector extension is able to effectively detect time tampering attacks, thereby providing an important security enhancement to the TTHCA algorithm. PMID:23686143

  8. A New MANET wormhole detection algorithm based on traversal time and hop count analysis.

    Science.gov (United States)

    Karlsson, Jonny; Dooley, Laurence S; Pulkkis, Göran

    2011-01-01

    As demand increases for ubiquitous network facilities, infrastructure-less and self-configuring systems like Mobile Ad hoc Networks (MANET) are gaining popularity. MANET routing security however, is one of the most significant challenges to wide scale adoption, with wormhole attacks being an especially severe MANET routing threat. This is because wormholes are able to disrupt a major component of network traffic, while concomitantly being extremely difficult to detect. This paper introduces a new wormhole detection paradigm based upon Traversal Time and Hop Count Analysis (TTHCA), which in comparison to existing algorithms, consistently affords superior detection performance, allied with low false positive rates for all wormhole variants. Simulation results confirm that the TTHCA model exhibits robust wormhole route detection in various network scenarios, while incurring only a small network overhead. This feature makes TTHCA an attractive choice for MANET environments which generally comprise devices, such as wireless sensors, which possess a limited processing capability. PMID:22247657

  9. From the Flamm-Einstein-Rosen bridge to the modern renaissance of traversable wormholes

    CERN Document Server

    Lobo, Francisco S N

    2016-01-01

    We consider the possibility of multiply-connected spacetimes, ranging from the Flamm-Einstein-Rosen bridge, geons, and the modern renaissance of traversable wormholes. A fundamental property in wormhole physics is the flaring-out condition of the throat, which through the Einstein field equation entails the violation of the null energy condition. In the context of modified theories of gravity, it has also been shown that the normal matter can be imposed to satisfy the energy conditions, and it is the higher order curvature terms, interpreted as a gravitational fluid, that sustain these non-standard wormhole geometries, fundamentally different from their counterparts in general relativity. We explore interesting features of these geometries, in particular, the physical properties and characteristics of these `exotic spacetimes'.

  10. On a class of stable, traversable Lorentzian wormholes in classical general relativity

    International Nuclear Information System (INIS)

    It is known that Lorentzian wormholes must be threaded by matter that violates the null energy condition. We phenomenologically characterize such exotic matter by a general class of microscopic scalar field Lagrangians and formulate the necessary conditions that the existence of Lorentzian wormholes imposes on them. Under rather general assumptions, these conditions turn out to be strongly restrictive. The most simple Lagrangian that satisfies all of them describes a minimally coupled massless scalar field with a reversed sign kinetic term. Exact, nonsingular, spherically symmetric solutions of Einstein's equations sourced by such a field indeed describe traversable wormhole geometries. These wormholes are characterized by two parameters: their mass and charge. Among them, the zero mass ones are particularly simple, allowing us to analytically prove their stability under arbitrary space-time dependent perturbations. We extend our arguments to nonzero mass solutions and conclude that at least a nonzero measure set of these solutions is stable

  11. Study of Geodesics and the Frame-dragging effect in a Rotating Traversable Wormhole

    CERN Document Server

    Pradhan, Parthapratim

    2016-01-01

    The complete equatorial causal geodesic structure of a rotating traversable wormhole is analyzed and it has been shown that the ISCO (Innermost Stable Circular Orbit) coincides at the throat of the wormhole for the retrograde rotation. By studying the effective potential we also find the radius of the circular photon orbit. The Periastron precession frequency and the nodal precession frequency have been derived for both of the direct and retrograde rotation. Moreover, we derive the exact Lense-Thirring precession frequency of a test gyro for the said wormhole and we show that this frequency is inversely proportional to the angular momentum $(a)$ of the wormhole along the pole in a certain range of $r \\,\\, (r < 16a^2)$ whereas it is directly proportional to the angular momentum of the spacetime for the other compact objects like black holes and pulsars.

  12. From the Flamm-Einstein-Rosen bridge to the modern renaissance of traversable wormholes

    Science.gov (United States)

    Lobo, Francisco S. N.

    2016-05-01

    We consider the possibility of multiply-connected spacetimes, ranging from the Flamm-Einstein-Rosen bridge, geons, and the modern renaissance of traversable wormholes. A fundamental property in wormhole physics is the flaring-out condition of the throat, which through the Einstein field equation entails the violation of the null energy condition (NEC). In the context of modified theories of gravity, it has also been shown that the normal matter can be imposed to satisfy the energy conditions, and it is the higher order curvature terms, interpreted as a gravitational fluid, that sustain these nonstandard wormhole geometries, fundamentally different from their counterparts in general relativity (GR). We explore interesting features of these geometries, in particular, the physical properties and characteristics of these ‘exotic spacetimes’.

  13. Nonminimal coupling for the gravitational and electromagnetic fields: Traversable electric wormholes

    International Nuclear Information System (INIS)

    We discuss new exact solutions of a three-parameter nonminimal Einstein-Maxwell model. The solutions describe static spherically symmetric objects with and without center, supported by an electric field nonminimally coupled to gravity. We focus on a unique one-parameter model, which admits an exact solution for a traversable electrically charged wormhole connecting two universes, one asymptotically flat the other asymptotically de Sitter ones. The relation between the asymptotic mass and charge of the wormhole and its throat radius is analyzed. The wormhole solution found is thus a nonminimal realization of Wheeler's idea about charge without charge and shows that, if the world is somehow nonminimal in the coupling of gravity to electromagnetism, then wormhole appearance, or perhaps construction, is possible.

  14. Data-Driven Surface Traversability Analysis for Mars 2020 Landing Site Selection

    Science.gov (United States)

    Ono, Masahiro; Rothrock, Brandon; Almeida, Eduardo; Ansar, Adnan; Otero, Richard; Huertas, Andres; Heverly, Matthew

    2015-01-01

    The objective of this paper is three-fold: 1) to describe the engineering challenges in the surface mobility of the Mars 2020 Rover mission that are considered in the landing site selection processs, 2) to introduce new automated traversability analysis capabilities, and 3) to present the preliminary analysis results for top candidate landing sites. The analysis capabilities presented in this paper include automated terrain classification, automated rock detection, digital elevation model (DEM) generation, and multi-ROI (region of interest) route planning. These analysis capabilities enable to fully utilize the vast volume of high-resolution orbiter imagery, quantitatively evaluate surface mobility requirements for each candidate site, and reject subjectivity in the comparison between sites in terms of engineering considerations. The analysis results supported the discussion in the Second Landing Site Workshop held in August 2015, which resulted in selecting eight candidate sites that will be considered in the third workshop.

  15. Rotating traversable wormholes in a noncommutative space and the energy conditions

    CERN Document Server

    Abreu, Everton M C

    2014-01-01

    It is a very well known fact that the energy conditions concerning traversable wormhole (WH) solutions of Einstein equations are violated. Consequently, attempts to avoid the violation of the energy conditions constitutes one of the main areas of research in WH physics. On the other hand, the current literature shows us that noncommutativity is one of the most promising candidates to help us to understand the physics of the early Universe. However, since noncommutativity does not change the commutative results, we also can expect that energy conditions violation near the throat must occur. We will show here that the violation of the energy conditions, described in a noncommutative space-time, has fixed conditions on the angular momentum of a rotating WH with constant angular velocity. Also, we have established a new theoretical bound on the NC constant, $\\theta$, as a function of some WH parameters.

  16. Dynamic response of arch bridges traversed by high-speed trains

    Science.gov (United States)

    Lacarbonara, Walter; Colone, Valerio

    2007-07-01

    A mechanical model describing the planar elasto-dynamics of arch bridges with general arch profiles is presented. The model is amenable to analytical or semi-analytical treatments and is effective for parametric studies, design of control systems or structural optimizations. The Ritz's energy approach is employed to calculate the solutions of the vibration eigenvalue problem—natural frequencies and mode shapes—and the forced responses to external excitations, namely those induced by the passage of trains. A closed-form solution of the bridge dynamic response to the transit of trains with arbitrary load distributions and running speeds is found and the train-induced resonances are accordingly discussed. In particular, three European high-speed trains—the French TGV, the Italian ETR 500, and the German ICE—traversing a lower-deck steel arch bridge are considered and the ensuing responses are investigated.

  17. E-field ratio telluric traverses near Fortymile Wash, Nevada Test Site, Nevada

    International Nuclear Information System (INIS)

    E-Field ratio telluric traverses have identified abrupt changes in resistivity at several places along the Fortymile Wash drainage. These resistivity changes have been interpreted to result from Basin and Range normal faulting along the wash. East of the Yucca Moutnain site four north-south trending faults have been identified. The central block between these faults comprises the graben through which Fortymile Wash flows. Further south the graben appears to be much broader and only the eastern boundary has been defined by telluric data near Lathrop Wells. Extrapolation of trends from either the northern two lines or the southern set does not give any correspondence. This suggests that cross structures may offset the Basin and Range faults between line 1 and line L-N. These lines are separated by 12 km (7.5 miles). In order to define the electrical structure in the intervening region additional work would be required

  18. Traversal of cells by radiation and absorbed fraction estimates for electrons and alpha particles

    International Nuclear Information System (INIS)

    Consideration of the pathlength which radiation traverses in a cell is central to algorithms for estimating energy deposition on a cellular level. Distinct pathlength distributions occur for radionuclides: (1) uniformly distributed in space about the cell (referred to as μ-randomness); (2) uniformly distributed on the surface of the cell (S-randomness); and (3) uniformly distributed within the cell volume (I-randomness). For a spherical cell of diameter d, the mean pathlengths are 2/3d, and 3/4d, respectively, for these distributions. Algorithms for simulating the path of radiation through a cell are presented and the absorbed fraction in the cell and its nucleus are tabulated for low energy electrons and alpha particles emitted on the surface of spherical cells. The algorithms and absorbed fraction data should be of interest to those concerned with the dosimetry of radionuclide-labeled monoclonal antibodies. 8 references, 3 figures, 2 tables

  19. Trypanosomosis in The Gambia: prevalence in working horses and donkeys detected by whole genome amplification and PCR, and evidence for interactions between trypanosome species

    Directory of Open Access Journals (Sweden)

    Jallow Jibril

    2008-02-01

    Full Text Available Abstract Background The Gambia has an increasing population of equidae largely used for agriculture and transportation. A review of cases at The Gambian Horse and Donkey Trust (GHDT indicated that a common reason for presentation is a poorly defined medical condition often attributed to trypanosomosis. There are few reports describing the prevalence or the range of clinical signs associated with infection with different species of trypanosomes in horses and donkeys, but given the importance of these animals, the role of trypanosomosis requires investigation. Results In total 241 animals from the Central River Division in The Gambia (183 horses and 58 donkeys were screened using Whole Genome Amplification (WGA followed by trypanosome species identification using polymerase chain reaction (PCR. The results indicated overall trypanosome prevalence of 91%; with an infection rate of 31% for Trypanosoma congolense Savannah, 87% for Trypanosoma vivax and 18% for Trypanosoma brucei sp. Multiple species were present in 43% of infections. Microscopy had a good specificity (100% and positive predictive value (100% for trypanosome detection, but the sensitivity (20% and negative predictive value (10.5% were low relative to PCR-based diagnosis. Infection with T congolense showed the greatest negative effect on packed cell volume (PCV, while infection with T. brucei sp also had a significant, although lesser, negative effect on PCV. In addition, cases positive by microscopy were associated with significantly lower PCV. However, concurrent infection with T. vivax appeared to cause less effect on PCV, compared to animals infected with T. congolense alone. Conclusion The prevalence of Trypanosomosis was high in both horses and donkeys. Infection with T. congolense appeared to have the greatest clinical significance, while T. vivax infection may be of limited clinical significance in this population. Indeed, there is evidence of T. vivax co-infection ameliorating

  20. Keeping African Masks Real

    Science.gov (United States)

    Waddington, Susan

    2012-01-01

    Art is a good place to learn about our multicultural planet, and African masks are prized throughout the world as powerfully expressive artistic images. Unfortunately, multicultural education, especially for young children, can perpetuate stereotypes. Masks taken out of context lose their meaning and the term "African masks" suggests that there is…

  1. Empowering African States

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    China helps bring lasting peace and stability to Africa African think tanks expressed a high opinion of China’s role in helping build African peace and security at the first meeting of the China-Africa Think Tanks Forum. The

  2. African Literature as Celebration.

    Science.gov (United States)

    Achebe, Chinua

    1989-01-01

    Describes the Igbo tradition of "Mbari," a communal creative enterprise that celebrates the world and the life lived in it through art. Contrasts the cooperative, social dimension of pre-colonial African culture with the exclusion and denial of European colonialism, and sees new African literature again celebrating human presence and dignity. (AF)

  3. Solving the Traveling Salesman’s Problem Using the African Buffalo Optimization

    Directory of Open Access Journals (Sweden)

    Julius Beneoluchi Odili

    2016-01-01

    Full Text Available This paper proposes the African Buffalo Optimization (ABO which is a new metaheuristic algorithm that is derived from careful observation of the African buffalos, a species of wild cows, in the African forests and savannahs. This animal displays uncommon intelligence, strategic organizational skills, and exceptional navigational ingenuity in its traversal of the African landscape in search for food. The African Buffalo Optimization builds a mathematical model from the behavior of this animal and uses the model to solve 33 benchmark symmetric Traveling Salesman’s Problem and six difficult asymmetric instances from the TSPLIB. This study shows that buffalos are able to ensure excellent exploration and exploitation of the search space through regular communication, cooperation, and good memory of its previous personal exploits as well as tapping from the herd’s collective exploits. The results obtained by using the ABO to solve these TSP cases were benchmarked against the results obtained by using other popular algorithms. The results obtained using the African Buffalo Optimization algorithm are very competitive.

  4. African Peacekeepers in Africa

    DEFF Research Database (Denmark)

    Emmanuel, Nikolas G.

    2015-01-01

    peacekeeping operations in the region. It is important to add that the international community has frequently tried to facilitate the deployment of African armed forces with aid and training. From this reality, the following study goes beyond the current literature by focusing on the international factors...... behind African participation in United Nations (UN) peacekeeping operations in Africa. In doing so, this research focuses on US military aid and foreign troop training from 2002 to 2012, and its impact on African deployments into UN peacekeeping missions in Africa. As can be expected, such third...

  5. Reading the African context

    OpenAIRE

    Musonda Bwalya

    2012-01-01

    There is so much alienation, pain and suffering in our today�s world. In this vein, African Christianity, a voice amongst many voices, should seek to be a transformational religion for the whole of life, affecting all facets of human life towards a fuller life of all in Africa. This article sought to highlight and point to some of the major societal challenges in the African context which African Christianity, as a life-affirming religion, should continue to embrace, re-embrace and engag...

  6. Capitalism and African business cultures

    OpenAIRE

    Taylor, Scott D.

    2014-01-01

    Scholars and practitioners once commonly linked 'African culture' to a distinctive 'African capitalism', at odds with genuine capitalism and the demands of modern business. Yet contemporary African business cultures reveal that a capitalist ethos has taken hold within both state and society. The success and visibility of an emergent, and celebrated, class of African big business reveals that business and profit are culturally acceptable. Existing theories of African capitalism are ill-equippe...

  7. Correlation of Particle Traversals with Clonogenic Survival Using Cell-Fluorescent Ion Track Hybrid Detector

    Directory of Open Access Journals (Sweden)

    Ivana eDokic

    2015-12-01

    Full Text Available Development of novel approaches linking the physical characteristics of particles with biological responses are of high relevance for the field of particle therapy. In radiobiology, the clonogenic survival of cells is considered the gold standard assay for assessment of cellular sensitivity to ionizing radiation. Towards further development of next generation biodosimeters in particle therapy, cell-fluorescent ion track hybrid detector (Cell-FIT-HD was recently engineered by our group and successfully employed to study physical particle track information in correlation with irradiation- induced DNA damage in cell nuclei. In this work, we investigated the feasibility of Cell-FIT-HD as a tool to study the effects of clinical beams on cellular clonogenic survival. Tumor cells were grown on the FNTD as cell culture, mimicking the standard procedures for clonogenic assay. Cell-FIT-HD was used to detect the spatial distribution of particle tracks within colony-initiating cells. The physical data were associated to radiation induced foci as surrogates for DNA double strand breakages (DSB, the hallmark of radiation ‐induced cell lethality. Long‐term cell fate was monitored to determine the ability of cells to form colonies. We report the first successful detection of particle traversal within colony-initiating cells at subcellular resolution using Cell-FIT-HD.

  8. Plane symmetric traversable wormholes in an anti-de Sitter background

    International Nuclear Information System (INIS)

    We construct solutions of plane symmetric wormholes in the presence of a negative cosmological constant by matching an interior spacetime to the exterior anti-de Sitter vacuum solution. The spatial topology of this plane symmetric wormhole can be planar, cylindrical, or toroidal. As usual, the null energy condition is necessarily violated at the throat. At the junction surface, the surface stresses are determined. By expressing the tangential surface pressure as a function of several parameters, namely, the matching radius, the radial derivative of the redshift function, and the surface energy density, the sign of the tangential surface pressure is analyzed. We then study four specific equations of state at the junction: the zero surface energy density, the constant redshift function, the domain wall equation of state, and the traceless surface stress-energy tensor. The equation governing the behavior of the radial pressure, in terms of the surface stresses and the extrinsic curvatures, is also displayed. Finally, we construct a model of a plane symmetric traversable wormhole which minimizes the usage of the exotic matter at the throat, i.e., the null energy condition is made arbitrarily small at the wormhole throat, while the surface stresses on the junction surface satisfy the weak energy condition, and consequently the null energy condition. The construction of these wormholes does not alter the topology of the background spacetime (i.e., spacetime is not multiply connected), so that these solutions can instead be considered domain walls. Thus, in general, these wormhole solutions do not allow time travel

  9. Work-related chronic neck impairment. Neck motion analysis in female traverse crane operators.

    Science.gov (United States)

    Alund, M; Larsson, S E; Lewin, T

    1992-09-01

    Twenty-one female steel industry traverse crane operators with long-term sick-leave (3 (1-8) years) due to chronic neck disability underwent careful analysis of case history, physical status and electrogoniometric three-dimensional recordings of active neck motion. Results were compared with those from working female crane operators having identical work posture and tasks and, further, with a group of working female clerks. The sick-listed crane operators had previous frequent contacts with the primary health care because of complaints from the neck and back. In comparison with the reference groups, the sick-listed crane operators showed tenderness of the trapezius and levator scapulae muscles and a short neck stature in combination with impaired active neck motion range with reduced motion speed. The motion pattern was however unchanged. The findings are consistent with the clinical picture of chronic neck myalgia that persisted despite long-term absence from the previous exposure to high static work load upon the neck-shoulders. PMID:1411359

  10. Ground-based real-time tracking and traverse recovery of China's first lunar rover

    Science.gov (United States)

    Zhou, Huan; Li, Haitao; Xu, Dezhen; Dong, Guangliang

    2016-02-01

    The Chang'E-3 unmanned lunar exploration mission forms an important stage in China's Lunar Exploration Program. China's first lunar rover "Yutu" is a sub-probe of the Chang'E-3 mission. Its main science objectives cover the investigations of the lunar soil and crust structure, explorations of mineral resources, and analyses of matter compositions. Some of these tasks require accurate real-time and continuous position tracking of the rover. To achieve these goals with the scale-limited Chinese observation network, this study proposed a ground-based real-time very long baseline interferometry phase referencing tracking method. We choose the Chang'E-3 lander as the phase reference source, and the accurate location of the rover is updated every 10 s using its radio-image sequences with the help of a priori information. The detailed movements of the Yutu rover have been captured with a sensitivity of several centimeters, and its traverse across the lunar surface during the first few days after its separation from the Chang'E-3 lander has been recovered. Comparisons and analysis show that the position tracking accuracy reaches a 1-m level.

  11. Traversable Lorentzian wormholes in the vacuum low energy effective string theory in Einstein and Jordan frames

    International Nuclear Information System (INIS)

    Three new classes (II-IV) of solutions of the vacuum low energy effective string theory in four dimensions are derived. Wormhole solutions are investigated in those solutions including the class I case both in the Einstein and in the Jordan (string) frame. It turns out that, of the eight classes of solutions investigated (four in the Einstein frame and four in the corresponding string frame), massive Lorentzian traversable wormholes exist in five classes. Nontrivial massless limit exists only in class I Einstein frame solution while none at all exists in the string frame. An investigation of test scalar charge motion in the class I solution in the two frames is carried out by using the Plebanski-Sawicki theorem. A curious consequence is that the motion around the extremal zero (Keplerian) mass configuration leads, as a result of scalar-scalar interaction, to a new hypothetical 'mass' that confines test scalar charges in bound orbits, but does not interact with neutral test particles

  12. A Block Cipher Algorithm for Multimedia Content Protection with Random Substitution using Binary Tree Traversal

    Directory of Open Access Journals (Sweden)

    P. Vidhya Saraswathi

    2012-01-01

    Full Text Available Many people consume multimedia content (images, music, movie on portable devices like DVD player, MP3 player, Portable Multimedia Player and also through Internet. Problem statement: The conventional algorithms such as DES and AES cannot be used directly in multimedia data, since multimedia data are repeatedly have high redundancy, large-volumes and require real-time operations, such as displaying, cutting, copying, bit-rate conversion and so forth. A block cipher is usually used to encrypt multimedia content because of its reasonable security and performance. Approach: In this study, we introduce a naive approach of efficient multimedia content encryption scheme which uses a block of bits rather than bytes or pixels. The proposed block cipher encrypts any type of compressed multimedia content by random substitution using binary tree traversal, row shifting and column shifting. Results: Experimental results show that the new algorithm has better performance than DES algorithm, encrypting multimedia content by dividing the plaintext by blocks. Conclusion: The proposed algorithm is implemented for all types of multimedia files like audio, video, images and text data and this algorithm can be used to multimedia data during transmisson through Internet or through any communication channels.

  13. Subcellular Spatial Correlation of Particle Traversal and Biological Response in Clinical Ion Beams

    Energy Technology Data Exchange (ETDEWEB)

    Niklas, Martin, E-mail: m.niklas@dkfz.de [Division of Medical Physics in Radiation Oncology, German Cancer Research Center, Heidelberg (Germany); German Cancer Consortium, National Center for Radiation Research in Oncology, Heidelberg Institute of Radiation Oncology, Heidelberg (Germany); Abdollahi, Amir [German Cancer Consortium, National Center for Radiation Research in Oncology, Heidelberg Institute of Radiation Oncology, Heidelberg (Germany); Molecular and Translational Radiation Oncology, Heidelberg Ion-Beam Therapy Center, University of Heidelberg Medical School and National Center for Tumor Diseases, German Cancer Research Center, Heidelberg (Germany); Department of Radiation Oncology and Radiation Therapy, University Hospital Heidelberg, Heidelberg (Germany); Heidelberg Ion-Beam Therapy Center, Heidelberg (Germany); Akselrod, Mark S. [Stillwater Crystal Growth Division, Landauer Inc, Stillwater, Oklahoma (United States); Debus, Jürgen [German Cancer Consortium, National Center for Radiation Research in Oncology, Heidelberg Institute of Radiation Oncology, Heidelberg (Germany); Molecular and Translational Radiation Oncology, Heidelberg Ion-Beam Therapy Center, University of Heidelberg Medical School and National Center for Tumor Diseases, German Cancer Research Center, Heidelberg (Germany); Department of Radiation Oncology and Radiation Therapy, University Hospital Heidelberg, Heidelberg (Germany); Heidelberg Ion-Beam Therapy Center, Heidelberg (Germany); Jäkel, Oliver [Division of Medical Physics in Radiation Oncology, German Cancer Research Center, Heidelberg (Germany); German Cancer Consortium, National Center for Radiation Research in Oncology, Heidelberg Institute of Radiation Oncology, Heidelberg (Germany); Department of Radiation Oncology and Radiation Therapy, University Hospital Heidelberg, Heidelberg (Germany); Heidelberg Ion-Beam Therapy Center, Heidelberg (Germany); and others

    2013-12-01

    Purpose: To report on the spatial correlation of physical track information (fluorescent nuclear track detectors, FNTDs) and cellular DNA damage response by using a novel hybrid detector (Cell-Fit-HD). Methods and Materials: The FNTDs were coated with a monolayer of human non-small cell lung carcinoma (A549) cells and irradiated with carbon ions (270.55 MeV u{sup −1}, rising flank of the Bragg peak). Phosphorylated histone variant H2AX accumulating at the irradiation-induced double-strand break site was labeled (RIF). The position and direction of ion tracks in the FNTD were registered with the location of the RIF sequence as an ion track surrogate in the cell layer. Results: All RIF sequences could be related to their corresponding ion tracks, with mean deviations of 1.09 μm and −1.72 μm in position and of 2.38° in slope. The mean perpendicular between ion track and RIF sequence was 1.58 μm. The mean spacing of neighboring RIFs exhibited a regular rather than random spacing. Conclusions: Cell-Fit-HD allows for unambiguous spatial correlation studies of cell damage with respect to the intracellular ion traversal under therapeutic beam conditions.

  14. Subcellular Spatial Correlation of Particle Traversal and Biological Response in Clinical Ion Beams

    International Nuclear Information System (INIS)

    Purpose: To report on the spatial correlation of physical track information (fluorescent nuclear track detectors, FNTDs) and cellular DNA damage response by using a novel hybrid detector (Cell-Fit-HD). Methods and Materials: The FNTDs were coated with a monolayer of human non-small cell lung carcinoma (A549) cells and irradiated with carbon ions (270.55 MeV u−1, rising flank of the Bragg peak). Phosphorylated histone variant H2AX accumulating at the irradiation-induced double-strand break site was labeled (RIF). The position and direction of ion tracks in the FNTD were registered with the location of the RIF sequence as an ion track surrogate in the cell layer. Results: All RIF sequences could be related to their corresponding ion tracks, with mean deviations of 1.09 μm and −1.72 μm in position and of 2.38° in slope. The mean perpendicular between ion track and RIF sequence was 1.58 μm. The mean spacing of neighboring RIFs exhibited a regular rather than random spacing. Conclusions: Cell-Fit-HD allows for unambiguous spatial correlation studies of cell damage with respect to the intracellular ion traversal under therapeutic beam conditions

  15. Landing Site Selection and Surface Traverse Planning using the Lunar Mapping & Modeling Portal

    Science.gov (United States)

    Law, E.; Chang, G.; Bui, B.; Sadaqathullah, S.; Kim, R.; Dodge, K.; Malhotra, S.

    2013-12-01

    Introduction: The Lunar Mapping and Modeling Portal (LMMP), is a web-based Portal and a suite of interactive visualization and analysis tools for users to access mapped lunar data products (including image mosaics, digital elevation models, etc.) from past and current lunar missions (e.g., Lunar Reconnaissance Orbiter, Apollo, etc.), and to perform in-depth analyses to support lunar surface mission planning and system design for future lunar exploration and science missions. It has been widely used by many scientists mission planners, as well as educators and public outreach (e.g., Google Lunar XPRICE teams, RESOLVE project, museums etc.) This year, LMMP was used by the Lunar and Planetary Institute (LPI)'s Lunar Exploration internship program to perform lighting analysis and local hazard assessments, such as, slope, surface roughness and crater/boulder distribution to research landing sites and surface pathfinding and traversal. Our talk will include an overview of LMMP, a demonstration of the tools as well as a summary of the LPI Lunar Exploration summer interns' experience in using those tools.

  16. Vibration suppression of curved beams traversed by off-center moving loads

    Science.gov (United States)

    Rostam, M. R.; Javid, F.; Esmailzadeh, E.; Younesian, D.

    2015-09-01

    In this study six different vibration control strategies are proposed to suppress both the flexural and torsional vibrations of a curved beam traversed by off-center moving loads. The various vibration control strategies employed are: (i) separate tuned-mass-dampers (TMDs), (ii) linked TMDs with a massless connecting rod, (iii) distributed TMDs system, (iv) linked TMDs with intermediate connection, (v) separate TMDs with intermediate dissipating system, and finally (vi) the nonlinear energy sinks (NESs). The curved beam is modeled using finite element model. An optimal design of TMD system is proposed to suppress the effect of non-symmetrical and side-way motion of vehicles traveling on bridges. The dynamic performance of the proposed vibration control strategies are thoroughly evaluated while subjected to different loading conditions: (a) successive moving loads and (b) broadband random excitation. It is shown that while all the proposed strategies can remarkably suppress both types of the vibration, the fifth strategy is the most effective one that provides the largest value of the bending and torsional vibration reduction in the first loading condition.

  17. An FMM based on dual tree traversal for many-core architectures

    KAUST Repository

    Yokota, Rio

    2013-09-01

    The present work attempts to integrate the independent efforts in the fast N-body community to create the fastest N-body library for many-core and heterogenous architectures. Focus is placed on low accuracy optimizations, in response to the recent interest to use FMM as a preconditioner for sparse linear solvers. A direct comparison with other state-of-the-art fast N-body codes demonstrates that orders of magnitude increase in performance can be achieved by careful selection of the optimal algorithm and low-level optimization of the code. The current N-body solver uses a fast multipole method with an efficient strategy for finding the list of cell-cell interactions by a dual tree traversal. A task-based threading model is used to maximize thread-level parallelism and intra-node load-balancing. In order to extract the full potential of the SIMD units on the latest CPUs, the inner kernels are optimized using AVX instructions.

  18. The Effect of Oscillating Traverse Welding on Performance of Cr-Fe-C Hardfacing Alloys

    Science.gov (United States)

    Lai, Hsuan-Han; Hsieh, Chih-Chun; Wang, Jia-Siang; Lin, Chi-Ming; Wu, Weite

    2015-11-01

    In this study, a series of experiments involving Cr-Fe-C hardfacing alloys is conducted to evaluate the effect of oscillating traverse welding on microstructure and performance of clad alloys. The alloys are designed to exhibit hypoeutectic, eutectic, and hypereutectic morphology. The morphology of the heat-affected zone (HAZ) of the unmelted metal, the solidified remelted metal, and the fusion boundary exhibited distinct characteristics. In the hypoeutectic and the eutectic alloys, the same lamellar eutectic structure can be observed as the solidified structure, and they also showed the same evolution in the HAZ. In the hypereutectic alloy, the incomplete weld pool blending results in a eutectic morphology instead of a fully hypereutectic morphology. The hardness result reveals that, for the hypereutectic alloy, the eutectic region, instead of the HAZ, is the weak point. The wear test shows that the hypoeutectic alloy exhibits the same wear behaviors in both the remelted metal and the HAZ, and so is the hypereutectic alloy; the eutectic alloy remelted metal and the HAZ have different wear morphologies.

  19. Regulating a Post-Transcriptional Regulator: Protein Phosphorylation, Degradation and Translational Blockage in Control of the Trypanosome Stress-Response RNA-Binding Protein ZC3H11.

    Directory of Open Access Journals (Sweden)

    Igor Minia

    2016-03-01

    Full Text Available The life cycle of the mammalian pathogen Trypanosoma brucei involves commuting between two markedly different environments: the homeothermic mammalian host and the poikilothermic invertebrate vector. The ability to resist temperature and other stresses is essential for trypanosome survival. Trypanosome gene expression is mainly post-transcriptional, but must nevertheless be adjusted in response to environmental cues, including host-specific physical and chemical stresses. We investigate here the control of ZC3H11, a CCCH zinc finger protein which stabilizes stress response mRNAs. ZC3H11 protein levels increase at least 10-fold when trypanosomes are stressed by heat shock, proteasome inhibitors, ethanol, arsenite, and low doses of puromycin, but not by various other stresses. We found that increases in protein stability and translation efficiency both contribute to ZC3H11 accumulation. ZC3H11 is an in vitro substrate for casein kinase 1 isoform 2 (CK1.2, and results from CK1.2 depletion and other experiments suggest that phosphorylation of ZC3H11 can promote its instability in vivo. Results from sucrose density centrifugation indicate that under normal culture conditions translation initiation on the ZC3H11 mRNA is repressed, but after suitable stresses the ZC3H11 mRNA moves to heavy polysomes. The ZC3H11 3'-UTR is sufficient for translation suppression and a region of 71 nucleotides is required for the regulation. Since the control works in both bloodstream forms, where ZC3H11 translation is repressed at 37°C, and in procyclic forms, where ZC3H11 translation is activated at 37°C, we predict that this regulatory RNA sequence is targeted by repressive trans acting factor that is released upon stress.

  20. Regulating a Post-Transcriptional Regulator: Protein Phosphorylation, Degradation and Translational Blockage in Control of the Trypanosome Stress-Response RNA-Binding Protein ZC3H11.

    Science.gov (United States)

    Minia, Igor; Clayton, Christine

    2016-03-01

    The life cycle of the mammalian pathogen Trypanosoma brucei involves commuting between two markedly different environments: the homeothermic mammalian host and the poikilothermic invertebrate vector. The ability to resist temperature and other stresses is essential for trypanosome survival. Trypanosome gene expression is mainly post-transcriptional, but must nevertheless be adjusted in response to environmental cues, including host-specific physical and chemical stresses. We investigate here the control of ZC3H11, a CCCH zinc finger protein which stabilizes stress response mRNAs. ZC3H11 protein levels increase at least 10-fold when trypanosomes are stressed by heat shock, proteasome inhibitors, ethanol, arsenite, and low doses of puromycin, but not by various other stresses. We found that increases in protein stability and translation efficiency both contribute to ZC3H11 accumulation. ZC3H11 is an in vitro substrate for casein kinase 1 isoform 2 (CK1.2), and results from CK1.2 depletion and other experiments suggest that phosphorylation of ZC3H11 can promote its instability in vivo. Results from sucrose density centrifugation indicate that under normal culture conditions translation initiation on the ZC3H11 mRNA is repressed, but after suitable stresses the ZC3H11 mRNA moves to heavy polysomes. The ZC3H11 3'-UTR is sufficient for translation suppression and a region of 71 nucleotides is required for the regulation. Since the control works in both bloodstream forms, where ZC3H11 translation is repressed at 37°C, and in procyclic forms, where ZC3H11 translation is activated at 37°C, we predict that this regulatory RNA sequence is targeted by repressive trans acting factor that is released upon stress. PMID:27002830

  1. Regulating a Post-Transcriptional Regulator: Protein Phosphorylation, Degradation and Translational Blockage in Control of the Trypanosome Stress-Response RNA-Binding Protein ZC3H11

    Science.gov (United States)

    Minia, Igor; Clayton, Christine

    2016-01-01

    The life cycle of the mammalian pathogen Trypanosoma brucei involves commuting between two markedly different environments: the homeothermic mammalian host and the poikilothermic invertebrate vector. The ability to resist temperature and other stresses is essential for trypanosome survival. Trypanosome gene expression is mainly post-transcriptional, but must nevertheless be adjusted in response to environmental cues, including host-specific physical and chemical stresses. We investigate here the control of ZC3H11, a CCCH zinc finger protein which stabilizes stress response mRNAs. ZC3H11 protein levels increase at least 10-fold when trypanosomes are stressed by heat shock, proteasome inhibitors, ethanol, arsenite, and low doses of puromycin, but not by various other stresses. We found that increases in protein stability and translation efficiency both contribute to ZC3H11 accumulation. ZC3H11 is an in vitro substrate for casein kinase 1 isoform 2 (CK1.2), and results from CK1.2 depletion and other experiments suggest that phosphorylation of ZC3H11 can promote its instability in vivo. Results from sucrose density centrifugation indicate that under normal culture conditions translation initiation on the ZC3H11 mRNA is repressed, but after suitable stresses the ZC3H11 mRNA moves to heavy polysomes. The ZC3H11 3'-UTR is sufficient for translation suppression and a region of 71 nucleotides is required for the regulation. Since the control works in both bloodstream forms, where ZC3H11 translation is repressed at 37°C, and in procyclic forms, where ZC3H11 translation is activated at 37°C, we predict that this regulatory RNA sequence is targeted by repressive trans acting factor that is released upon stress. PMID:27002830

  2. Differential trypanosome surface coat regulation by a CCCH protein that co-associates with procyclin mRNA cis-elements.

    Directory of Open Access Journals (Sweden)

    Pegine Walrad

    2009-02-01

    Full Text Available The genome of Trypanosoma brucei is unusual in being regulated almost entirely at the post-transcriptional level. In terms of regulation, the best-studied genes are procyclins, which encode a family of major surface GPI-anchored glycoproteins (EP1, EP2, EP3, GPEET that show differential expression in the parasite's tsetse-fly vector. Although procyclin mRNA cis-regulatory sequences have provided the paradigm for post-transcriptional control in kinetoplastid parasites, trans-acting regulators of procyclin mRNAs are unidentified, despite intensive effort over 15 years. Here we identify the developmental regulator, TbZFP3, a CCCH-class predicted RNA binding protein, as an isoform-specific regulator of Procyclin surface coat expression in trypanosomes. We demonstrate (i that endogenous TbZFP3 shows sequence-specific co-precipitation of EP1 and GPEET, but not EP2 and EP3, procyclin mRNA isoforms, (ii that ectopic overexpression of TbZFP3 does not perturb the mRNA abundance of procyclin transcripts, but rather that (iii their protein expression is regulated in an isoform-specific manner, as evidenced by mass spectrometric analysis of the Procyclin expression signature in the transgenic cell lines. The TbZFP3 mRNA-protein complex (TbZFP3mRNP is identified as a trans-regulator of differential surface protein expression in trypanosomes. Moreover, its sequence-specific interactions with procyclin mRNAs are compatible with long-established predictions for Procyclin regulation. Combined with the known association of TbZFP3 with the translational apparatus, this study provides a long-sought missing link between surface protein cis-regulatory signals and the gene expression machinery in trypanosomes.

  3. Trypanosomes and haemosporidia in the buzzard (Buteo buteo) and sparrowhawk (Accipiter nisus): factors affecting the prevalence of parasites.

    Science.gov (United States)

    Svobodová, Milena; Weidinger, Karel; Peške, Lubomír; Volf, Petr; Votýpka, Jan; Voříšek, Petr

    2015-02-01

    The prevalences of heteroxenous parasites are influenced by the interplay of three main actors: hosts, vectors, and the parasites themselves. We studied blood protists in the nesting populations of raptors in two different areas of the Czech Republic. Altogether, 788 nestlings and 258 adult Eurasian sparrowhawks (Accipiter nisus) and 321 nestlings and 86 adult common buzzards (Buteo buteo) were screened for parasites by the microscopic examination of blood smears and by cultivation. We examined the role of shared vectors and parasite phylogenetic relationships on the occurrence of parasites. In different years and hosts, trypanosome prevalence ranged between 1.9 and 87.2 %, that of Leucocytozoon between 1.9 and 100 %, and Haemoproteus between 0 and 72.7 %. Coinfections with Leucocytozoon and Trypanosoma, phylogenetically distant parasites but both transmitted by blackflies (Simuliidae), were more frequent than coinfections with Leucocytozoon and Haemoproteus, phylogenetically closely related parasites transmitted by different vectors (blackflies and biting midges (Ceratopogonidae), respectively). For example, 16.6 % buzzard nestlings were coinfected with Trypanosoma and Leucocytozoon, while only 4.8 % with Leucocytozoon and Haemoproteus and 0.3 % with Trypanosoma and Haemoproteus. Nestlings in the same nest tended to have the same infection status. Furthermore, prevalence increased with the age of nestlings and with Julian date, while brood size had only a weak negative/positive effect on prevalence at the individual/brood level. Prevalences in a particular avian host species also varied between study sites and years. All these factors should thus be considered while comparing prevalences from different studies, the impact of vectors being the most important. We conclude that phylogenetically unrelated parasites that share the same vectors tend to have similar distributions within the host populations of two different raptor species. PMID:25403377

  4. Carbon monoxide levels in popular passenger commuting modes traversing major commuting routes in Hong Kong

    International Nuclear Information System (INIS)

    Vehicle exhaust is a major source of air pollution in metropolitan cities. Commuters are exposed to high traffic-related pollutant concentrations. Public transportation is the most popular commuting mode in Hong Kong and there are about 10.8 million passenger trips every day. Two-thirds of them are road commuters. An extensive survey was conducted to measure carbon monoxide in three popular passenger commuting modes, bus, minibus, and taxi, which served, respectively, 3.91 million, 1.76 million and 1.31 million passenger trips per day in 1998. Three types of commuting microenvironments were selected: urban-urban, urban-suburban and urban-rural. Results indicated that in-vehicle CO level increased in the following order: bus, minibus and taxi. The overall average in-vehicle CO level in air-conditioned bus, minibus and taxi were 1.8, 2.9 and 3.3ppm, respectively. The average concentration level between air-conditioned buses (1.8ppm) and non-air-conditioned buses (1.9ppm) was insignificant. The fluctuation of in-vehicle CO level of non-air-conditioned vehicle followed the variation of out-vehicle CO concentration. Our result also showed that even in air-conditioned vehicles, the in-vehicle CO concentration was affected by the out-vehicle CO concentration although there exists a smoothing out effect. The in-vehicle CO level was the highest in urban-suburban commuting routes and was followed by urban-urban routes. The in-vehicle CO level in urban-rural routes was the lowest. The highest CO level was recorded after the vehicle traversed through tunnel.. The average CO exposure level of public road transportation commuters in Honk Kong was lower than most other cities. Factors governing the CO levels were also discussed. (Author)

  5. Variations in snow and firn chemistry along US ITASE traverses and the effect of surface glazing

    Directory of Open Access Journals (Sweden)

    D. A. Dixon

    2013-03-01

    Full Text Available This study provides a baseline from which changes in the chemistry of the atmosphere over Antarctica can be monitored under expected warming scenarios and continued intensification of industrial activities in the Southern Hemisphere. It is the first study to measure more than 25 chemical constituents in the surface snow and firn across extensive regions of Antarctica. We present major ion, trace element, heavy metal, rare earth element and oxygen isotope data from a series of surface snow samples and shallow firn sections collected along four US ITASE traverses across East and West Antarctica. In each sample we measure dissolved concentrations of Na+, K+, Mg2+, Ca2+, Cl−, NO3+, SO42−, and MS− using ion chromatography and total concentrations of Sr, Cd, Cs, Ba, La, Ce, Pr, Pb, Bi, U, As, Al, S, Ca, Ti, V, Cr, Mn, Fe, Co, Na, Mg, Li, and K using inductively coupled plasma sector field mass spectrometry (ICP-SFMS. We also measure δ18O by isotope ratio mass spectrometry. Satellite remote sensing measurements of microwave backscatter and grain size are used to assist in the identification of glaze/dune areas across Antarctica and determine if these areas can possibly contain useful chemical climate records. The majority of the non-glaze/dune samples in this study exhibit similar, or lower, concentrations to those from previous studies. Consequently, the results presented here comprise a conservative baseline for Antarctic surface snow chemical concentrations. The elements Cd, Pb, As and Bi are enriched across Antarctica relative to both ocean and upper crust elemental ratios. Local and global volcanic outgassing may account for the majority of the Bi measured in East and West Antarctica and for a significant fraction of the Cd and As. However, significant concentrations of Cd, Pb, and As remain across much of Antarctica.

  6. Comparing Geologic Data Sets Collected by Planetary Analog Traverses and by Standard Geologic Field Mapping: Desert Rats Data Analysis

    Science.gov (United States)

    Feng, Wanda; Evans, Cynthia; Gruener, John; Eppler, Dean

    2014-01-01

    Geologic mapping involves interpreting relationships between identifiable units and landforms to understand the formative history of a region. Traditional field techniques are used to accomplish this on Earth. Mapping proves more challenging for other planets, which are studied primarily by orbital remote sensing and, less frequently, by robotic and human surface exploration. Systematic comparative assessments of geologic maps created by traditional mapping versus photogeology together with data from planned traverses are limited. The objective of this project is to produce a geologic map from data collected on the Desert Research and Technology Studies (RATS) 2010 analog mission using Apollo-style traverses in conjunction with remote sensing data. This map is compared with a geologic map produced using standard field techniques.

  7. A preliminary application GIS in glaciological research along the traverse route from Zhongshan Station to Dome A, Antarctica

    Institute of Scientific and Technical Information of China (English)

    温家洪; 孙波; 康建成; 李院生

    2003-01-01

    GIS is applied in glaciological research along the traverse route from Zhongshan Station to Dome A, one of the key routes in ITASE project, to display, process, manage and analyze the data obtained mainly by the 3rd Chinese Inland Expedition, together with Antarctic databases provided by ADD and BEDMAP project.The ways of ADD data merging and clipping, and coordinate projection transformation of field data and BEDMAP data are introduced.Elevation data derived by GPS navigator are corrected using ADD and ArcView's contour interpolation.Sub-ice topography and ice thickness along the route are extracted from BEDMAP database.Slope and aspect data are derived at each positioning station.GIS is a convenient and useful tool for us to record, query and display a variety of data in detail along the traverse route.

  8. The Transnational Turn in African Literature of French Expression: Imagining Other Utopic Spaces in the Globalized Age

    Directory of Open Access Journals (Sweden)

    Valérie K. Orlando

    2016-05-01

    Full Text Available This article focuses on African literature published since 2000 by authors of French expression. While contemporary authors’ subjects are varied—ranging from climate change, human rights, to ethnic cleansing—they also imagine new “what ifs” and other utopic spaces and places that extend beyond postcolonial, Africa-as-victim paradigms. Literarily, authors such as Abdelaziz Belkhodja (Tunisia and Abdourahman A. Waberi (Djibouti have effectuated a transnational turn. In this literary transnational turn, Africa is open to new interpretations by the African author that are very different from the more essentialist-based, literary-philosophical movements such as Negritude and pan-Africanism; cornerstones of the postcolonial literary frameworks of the past. Belkhodja and Waberi offer original narratives for Africa that, while describing their countries as utopias, also traverse the very dystopic realities of our time.

  9. Traversal of a polarized epithelium by pathogenic Neisseriae: facilitation by type IV pili and maintenance of epithelial barrier function.

    OpenAIRE

    Merz, A. J.; Rifenbery, D. B.; Arvidson, C. G.; So, M

    1996-01-01

    BACKGROUND: Gonococci (GC) and meningococci (MC) are gram-negative bacterial pathogens that infect human mucosal epithelia. We would like to understand the functions of specific bacterial components at each stage of mucosal colonization: adhesion, cell invasion, and traversal into subepithelial tissues. As no animal model of mucosal colonization by GC or MC is available, increasingly sophisticated in vitro approaches have been used to address these issues. MATERIALS AND METHODS: We adapted th...

  10. Non-ionizing radiofrequency electromagnetic waves traversing the head can be used to detect cerebrovascular autoregulation responses

    OpenAIRE

    Oziel, M.; M. Hjouj; Gonzalez, C.A.; Lavee, J.; Rubinsky, B

    2016-01-01

    Monitoring changes in non-ionizing radiofrequency electromagnetic waves as they traverse the brain can detect the effects of stimuli employed in cerebrovascular autoregulation (CVA) tests on the brain, without contact and in real time. CVA is a physiological phenomenon of importance to health, used for diagnosis of a number of diseases of the brain with a vascular component. The technology described here is being developed for use in diagnosis of injuries and diseases of the brain in rural an...

  11. Sustainable rural learning ecologies- a prolegomenon traversing transcendence of discursive notions of sustainability, social justice, development and food sovereignty

    OpenAIRE

    Hlalele, Dipane

    2013-01-01

    This paper contributes, through traversing contested notions of sustainability, social justice, development and food sovereignty, to discourses around creation of sustainable rural learning ecologies. There has always been at least in the realm of scientific discourse, an attempt to dissociate the natural or physical environment from the social and human environment. This trend did not only affect the two spheres of existence only. It is further imbued and spawned fragmented an...

  12. Molecular differential diagnosis of African Trypanosomosis in Uganda

    International Nuclear Information System (INIS)

    Out of 106 Trypanosomal DNAs from infected domestic animals, 77 (72.6%) were resolved into different Trypanosome species using primers based on ribosomal internal transcribed spacer-1 region in a single PCR (ITS-PCR). The remaining 29 (27.4%) Trypanosomal DNA samples were negative by ITS-PCR, but were positive by TBR-PCR, indicating that they were Trypanozoon Trypanosomes where the ITS-PCR could not resolve their identities. This was possibly due to the low amounts of DNA in the extracts which could not be picked up by ITS-PCR. The TBR-PCR was able to resolve all 106 Trypanosome isolates into 88 Trypanozoon and 18 others, which were identified and confirmed as T.congolense (6) and T.vivax (12) Trypanosomes. In addition, a total of 58 (89.2%) of the 65 (53 from cows and 12 from pigs) Trypanosome isolates from domestic animals in T.b.gambiense endemic areas in North West Uganda were positive by TBR-PCR, indicating that they were Trypanozoon Trypanosomes while 7 (10.8%) of the Trypanosome isolates were TBR-PCR negative, indicating that they were possibly not T.brucei ssp and could be T.congolense, T.vivax or T.theileri. Indeed, the 7 Trypanosome isolates were confirmed to be T.congolense (2) and T.vivax (5) using species specific primers. Furthermore, 31 of the 58 TBR-PCR positive Trypanosomal DNA samples analysed were TgsGP-PCR negative, indicating that they were not T.b.gambiense and hence no domestic animals identified as reservoir of T.b.gambiense. Additionally, all the 31 Trypanosomal DNA samples were SRA-PCR negative, indicating that there is probably no mixed infection of the two diseases, T.b.gambiense and T.b.rhodesiense in North West Uganda. Analysis of Trypanosomes derived from domestic animals from T.b.rhodesiense endemic areas in South East Uganda showed that, 79 (90.8%) of the 87 Trypanosomes isolated from cattle were positive by TBR-PCR, indicating that they were Trypanozoon while 8 (9.2%) were negative, suggesting that they could be T.vivax, T

  13. Obstacle traversal and self-righting of bio-inspired robots reveal the physics of multi-modal locomotion

    Science.gov (United States)

    Li, Chen; Fearing, Ronald; Full, Robert

    Most animals move in nature in a variety of locomotor modes. For example, to traverse obstacles like dense vegetation, cockroaches can climb over, push across, reorient their bodies to maneuver through slits, or even transition among these modes forming diverse locomotor pathways; if flipped over, they can also self-right using wings or legs to generate body pitch or roll. By contrast, most locomotion studies have focused on a single mode such as running, walking, or jumping, and robots are still far from capable of life-like, robust, multi-modal locomotion in the real world. Here, we present two recent studies using bio-inspired robots, together with new locomotion energy landscapes derived from locomotor-environment interaction physics, to begin to understand the physics of multi-modal locomotion. (1) Our experiment of a cockroach-inspired legged robot traversing grass-like beam obstacles reveals that, with a terradynamically ``streamlined'' rounded body like that of the insect, robot traversal becomes more probable by accessing locomotor pathways that overcome lower potential energy barriers. (2) Our experiment of a cockroach-inspired self-righting robot further suggests that body vibrations are crucial for exploring locomotion energy landscapes and reaching lower barrier pathways. Finally, we posit that our new framework of locomotion energy landscapes holds promise to better understand and predict multi-modal biological and robotic movement.

  14. Transactivating-transduction protein-polyethylene glycol modified liposomes traverse the blood-spinal cord and blood-brain barriers

    Institute of Scientific and Technical Information of China (English)

    Xianhu Zhou; Chunyuan Wang; Shiqing Feng; Jin Chang; Xiaohong Kong; Yang Liu; Shijie Gao

    2012-01-01

    Naive liposomes can cross the blood-brain barrier and blood-spinal cord barrier in small amounts. Liposomes modified by a transactivating-transduction protein can deliver antibiotics for the treatment of acute bacterial infection-induced brain inflammation. Liposomes conjugated with polyethylene glycol have the capability of long-term circulation. In this study we prepared transactivating-transduction protein-polyethylene glycol-modified liposomes labeled with fluorescein isothiocyanate. Thus, liposomes were characterized by transmembrane, long-term circulation and fluorescence tracing. Uptake, cytotoxicity, and the ability of traversing blood-spinal cord and blood-brain barriers were observed following coculture with human breast adenocarcinoma cells (MCF-7). Results demonstrated that the liposomes had good biocompatibility, and low cytotoxicity when cocultured with human breast adenocarcinoma cells. Liposomes could traverse cell membranes and entered the central nervous system and neurocytes through the blood-spinal cord and blood-brain barriers of rats via the systemic circulation. These results verified that fluorescein isothiocyanate-modified transactivating-transduction protein-polyethylene glycol liposomes have the ability to traverse the blood-spinal cord and blood-brain barriers.

  15. Characterizing the admixed African ancestry of African Americans

    OpenAIRE

    Zakharia, Fouad; Basu, Analabha; Absher, Devin; Assimes, Themistocles L.; Go, Alan S.; Hlatky, Mark A.; Iribarren, Carlos; Knowles, Joshua W.; Li, Jun; Narasimhan, Balasubramanian; Sidney, Steven; Southwick, Audrey; Myers, Richard M.; Quertermous, Thomas; Risch, Neil

    2009-01-01

    Abstract Background Accurate, high-throughput genotyping allows the fine characterization of genetic ancestry. Here we applied recently developed statistical and computational techniques to the question of African ancestry in African Americans by using data on more than 450,000 single-nucleotide polymorphisms (SNPs) genotyped in 94 Africans of diverse geographic origins included in the...

  16. African-Americans and Alzheimer's

    Science.gov (United States)

    ... Share Plus on Google Plus African-Americans and Alzheimer's alz.org | IHaveAlz Introduction 10 Warning Signs Brain ... African-Americans are at a higher risk for Alzheimer's disease. Many Americans dismiss the warning signs of ...

  17. Epidemiological aspects of bovine trypanosomosis in an endemic focus of eastern Zambia: The role of trypanosome strain variability in disease pattern

    Directory of Open Access Journals (Sweden)

    Justin Masumu

    2012-06-01

    Full Text Available Bovine trypanosomosis displays various epidemiological aspects in various areas. In some instances the disease has a high prevalence in animals with high impact on production whereas in other cases the disease has a low impact on production despite a high level of infection in animals. In addition epidemiological changes are frequently observed in various areas and are related to many factors including the vectors, the host, the parasites, the environment as well as the livestock management. However the implication of these factors in these changes is not fully elucidated. In eastern Zambia, factors predicting the establishment of severe infection in cattle are all present. However trypanosomosis occurring in cattle in this area has a low impact on livestock production. Several studies on the characterisation of trypanosome strains circulating in domestic and wild animals have been conducted in order to clarify the epidemiology of this disease in this area. These studies aimed at evaluating genetic and biological characteristics of these strains including their virulence profiles, their transmissibility by tsetse flies, their resistance to drugs and interference between different strains. In this review these findings are analysed in order to elucidate the implication of trypanosome strain variability in the distribution and the expression of this disease in the study area. The evolutionary trends of the situation occurring in this study area are also explained. Use of these findings is the context of disease control in the study area is further discussed.

  18. Anti-trypanosomal activity of pentacyclic triterpenes isolated from Austroplenckia populnea (Celastraceae Atividade anti-tripanosomicida de triterpenes pentacíclicos isolados de Austroplenckia populnea (Celastraceae

    Directory of Open Access Journals (Sweden)

    Lucienir Pains DUARTE

    2002-04-01

    Full Text Available Four pentacyclic triterpenes isolated from Austroplenckia populnea and four compounds of known anti T. cruzi or anti-malarial activity were tested. Of those triterpenes tested 20alpha-hydroxy-tingenone showed high activity, epikatonic acid was less active, while populnilic and populninic acids were inactive against the trypanosome of the subgenus Schizotrypanum tested. Benzonidazole, nifurtimox, ketoconazole and primaquine presented a remarkable dose-dependent inhibitory effect reaching practically to a total growth inhibition of the parasite at the end of incubation time. The trypanosome tested appear to be a suitable model for preliminary screen for anti T. (S. cruzi compounds.Foram testados quatro triterpenos pentacíclicos isolados de Austroplenckia populnea e quatro compostos de conhecida atividade anti-T. cruzi ou anti-malárica. Dos triterpenos testados 20alfa-hidroxi-tingenona mostrou atividade elevada, ácido epicatônico foi menos ativo, enquanto ácido populnílico e populnínico foram inativos contra o tripanossoma do subgênero Schizotrypanum testado. Benzonidazole, nifurtimox, cetoconazole e primaquina apresentaram efeito inibitório dose-dependente atingindo praticamente a inibição total do crescimento do parasita no final do tempo de incubação. O tripanossoma testado mostrou ser um modelo adequado para uma seleção preliminar de compostos anti. T. (S. cruzi.

  19. African Cultural Astronomy

    CERN Document Server

    Holbrook, Jarita C; Medupe, R. Thebe; Current Archaeoastronomy and Ethnoastronomy research in Africa

    2008-01-01

    Astronomy is the science of studying the sky using telescopes and light collectors such as photographic plates or CCD detectors. However, people have always studied the sky and continue to study the sky without the aid of instruments this is the realm of cultural astronomy. This is the first scholarly collection of articles focused on the cultural astronomy of Africans. It weaves together astronomy, anthropology, and Africa. The volume includes African myths and legends about the sky, alignments to celestial bodies found at archaeological sites and at places of worship, rock art with celestial imagery, and scientific thinking revealed in local astronomy traditions including ethnomathematics and the creation of calendars. Authors include astronomers Kim Malville, Johnson Urama, and Thebe Medupe; archaeologist Felix Chami, and geographer Michael Bonine, and many new authors. As an emerging subfield of cultural astronomy, African cultural astronomy researchers are focused on training students specifically for do...

  20. A new paradigm for Summit: enhanced traverse capabilities and satellite camps.`

    Science.gov (United States)

    Hawley, R. L.; Burkhart, J. F.; Courville, Z.; Dibb, J. E.

    2013-12-01

    served by the logistics of the Greenland Inland Traverse.

  1. African names for American plants

    NARCIS (Netherlands)

    Andel, van T.R.

    2015-01-01

    African slaves brought plant knowledge to the New World, sometimes applying it to related plants they found there and sometimes bringing Old World plants with them. By tracing the linguistic parallels between names for plants in African languages and in communities descended from African slaves, pie

  2. The Struggles over African Languages

    Science.gov (United States)

    Maseko, Pam; Vale, Peter

    2016-01-01

    In this interview, African Language expert Pam Maseko speaks of her own background and her first encounter with culture outside of her mother tongue, isiXhosa. A statistical breakdown of South African languages is provided as background. She discusses Western (originally missionary) codification of African languages and suggests that this approach…

  3. African agricultural trade

    DEFF Research Database (Denmark)

    Jensen, Hans Grinsted; Sandrey, Ron

    2015-01-01

    This article starts with a profile of African agricultural trade. Using the pre-release version 9.2 of the GTAP database, we then show that the results for tariff elimination on intra-African trade are promising, but these tariff barriers are not as significant as the various trade-related barriers...... elimination, non-tariff barrier reductions and time in transit cost reductions are likely to be cumulative and would generate very large gains to Africa. The policy implications are clear: while cooperation will enhance the gains, much of the benefits will result from unilateral actions and regional...

  4. Factors that influence rural African American males' aspirations to attend college

    Science.gov (United States)

    Stuart, Alesia K.

    This study was conducted to research factors which influence rural African American males in their college attendance decision. The study was an attempt to discover specific influences in the higher education pursuit from aspiration to enrollment. As African American males and low income students represent lower enrollment figures in higher education, this study attempts to provide research which may improve these numbers. The literature which provides the theoretical frame is related to Hossler (et al., 1999) and his research entitled Going to College. Hossler's study recommended additional research to study African American males. Hossler concluded this participant segment was influenced by different factors than the majority of study participants. This qualitative study includes student interviews. Three high schools in three counties in the Black Belt of rural Alabama were the sites selected for participants. Thirty African American male seniors' responses were transcribed and coded to identify themes related to influences stated by the participants. The students' voices provided insight into their college enrollment pursuit. The findings indicate rural students lack the resources and academic preparation significant for higher education admission. African American males in rural Alabama tend to be first generation students and lack information important to college enrollment. The rural high schools lack the personnel, college and career guidance to ensure participants are aware and prepared to traverse the process of college enrollment. This study identifies policy development needs to address inadequacies that African American males attending rural schools encounter during secondary enrollment. Research participants state college aspirations. Problems arise as participants move from the aspiration stage toward enrollment. Several factors will limit higher education opportunities for the participants. Inadequate knowledge on ACT scores, college cost financial

  5. An essential nuclear protein in trypanosomes is a component of mRNA transcription/export pathway.

    Directory of Open Access Journals (Sweden)

    Mariana Serpeloni

    decrease of translation levels, reinforcing that Trypanosoma-Sub2 (Tryp-Sub2 is a component of mRNA transcription/export pathway in trypanosomes.

  6. Deepening African Ties

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Chinese President Hu Jintao has just embarked on his state visits to eight African countries that will take him to both the northern and southern tips of the continent. This is his first trip abroad this year, and also his third visit to Africa

  7. East African institutions

    DEFF Research Database (Denmark)

    Nordby, Johannes Riber; Jacobsen, Katja

    For the past decade security in East Africa has gained focus internationally. However there is a growing ambition among African states to handle such issues by themselves, sometimes through regional institutions. This has been supported by many Western states but potential risks are often forgotten....

  8. African Women Writing Resistance

    Institute of Scientific and Technical Information of China (English)

    Jennifer Browdy de Hernandez; Pauline Dongala; Omotayo; Jolaosho; Anne Serafin

    2011-01-01

    AFRICAN Women Writing Resistance is the first transnational anthology to focus on women's strategies of resistance to the challenges they face in Africa today.The anthology brings together personal narratives,testimony,interviews,short stories,poetry,performance scripts,folktales and lyrics.

  9. African Women Writing Resistance

    Institute of Scientific and Technical Information of China (English)

    Jennifer; Browdy; de; Hernandez; Pauline; Dongala; Omotayo; Jolaosho; Anne; Serafin

    2011-01-01

    An Anthology of Contemporary Voices AFRICAN Women Writing Resistance is the first transnational anthology to focus on women’s strategies of resistance to the challenges they face in Africa today.The anthology brings together personal narratives,testimony,interviews, short stories,po-

  10. West African Antislavery Movements

    DEFF Research Database (Denmark)

    Hahonou, Eric Komlavi; Pelckmans, Lotte

    2011-01-01

    In the context of liberalization of West African political regimes, the upsurge of audacious political entrepreneurs who want to end chattel slavery in their nation-state, resulted in the legal criminalisation of slavery in both Mauritania (2007) and Niger (2003) and in a proposal to revise the...... cultures (or ‘mentalities’) go hand in hand....

  11. Immunizations and African Americans

    Science.gov (United States)

    ... Program Grants Other Grants Planning and Evaluation Grantee Best Practices Black/African American Asthma Cancer Chronic Liver Disease ... 13 to 17 years who ever received the human papillomavirus (HPV) vaccination, 2014 - Males # doses ... 240-453-2882 Office of Minority Health Resource Center Toll Free: 1-800-444-6472 / Fax: ...

  12. The African Union

    DEFF Research Database (Denmark)

    Mandrup, Thomas; Mandrup, Bjørn

    2009-01-01

    . Moreover, the ‘African Security Architecture’, of which it is the central component, also includes sub-regional organisations to which responsibility is to be devolved for dealing with armed confl ict and other matters. These so-called Regional Economic Communities (RECs) are, likewise, constantly changing...

  13. African tick bite fever

    DEFF Research Database (Denmark)

    Johansen, Jakob Aaquist; Thybo, Søren

    2011-01-01

    The incident of spotted fever imported to Denmark is unknown. We present a classic case of African Tick Bite Fever (ATBF) to highlight a disease, which frequently infects wildlife enthusiasts and hunters on vacation in South Africa. ATBF has a good prognosis and is easily treated with doxycyclin...

  14. Microbial methanogenesis in the sulfate-reducing zone of surface sediments traversing the Peruvian margin

    Directory of Open Access Journals (Sweden)

    J. Maltby

    2015-09-01

    Full Text Available We studied the concurrence of methanogenesis and sulfate reduction in surface sediments (0–25 cm below sea floor, cmbsf at six stations (70, 145, 253, 407, 770 and 1024 m along the Peruvian margin (12° S. This oceanographic region is characterized by high carbon export to the seafloor, creating an extensive oxygen minimum zone (OMZ on the shelf, both factors that could favor surface methanogenesis. Sediments sampled along the depth transect traversed areas of anoxic and oxic conditions in the bottom-near water. Net methane production (batch incubations and sulfate reduction (35S-sulfate radiotracer incubation were determined in the upper 0–25 cmbsf of multicorer cores from all stations, while deep hydrogenotrophic methanogenesis (> 30 cmbsf, 14C-bicarbonate radiotracer incubation was determined in two gravity cores at selected sites (78 and 407 m. Furthermore, stimulation (methanol addition and inhibition (molybdate addition experiments were carried out to investigate the relationship between sulfate reduction and methanogenesis. Highest rates of methanogenesis and sulfate reduction in the surface sediments, integrated over 0–25 cmbsf, were observed on the shelf (70–253 m, 0.06–0.1 and 0.5–4.7 mmol m−2 d−1, respectively, while lowest rates were discovered at the deepest site (1024 m, 0.03 and 0.2 mmol m−2 d−1, respectively. The addition of methanol resulted in significantly higher surface methanogenesis activity, suggesting that the process was mostly based on non-competitive substrates, i.e., substrates not used by sulfate reducers. In the deeper sediment horizons, where competition was probably relieved due to the decline of sulfate, the usage of competitive substrates was confirmed by the detection of hydrogenotrophic activity in the sulfate-depleted zone at the shallow shelf station (70 m. Surface methanogenesis appeared to be correlated to the availability of labile organic matter (C / N ratio and organic carbon

  15. Microbial methanogenesis in the sulfate-reducing zone of surface sediments traversing the Peruvian margin

    Science.gov (United States)

    Maltby, J.; Sommer, S.; Dale, A. W.; Treude, T.

    2016-01-01

    We studied the concurrence of methanogenesis and sulfate reduction in surface sediments (0-25 cm below sea floor) at six stations (70, 145, 253, 407, 990 and 1024 m) along the Peruvian margin (12° S). This oceanographic region is characterized by high carbon export to the seafloor creating an extensive oxygen minimum zone (OMZ) on the shelf, both factors that could favor surface methanogenesis. Sediments sampled along the depth transect traversed areas of anoxic and oxic conditions in the bottom-near water. Net methane production (batch incubations) and sulfate reduction (35S-sulfate radiotracer incubation) were determined in the upper 0-25 cm b.s.f. of multiple cores from all stations, while deep hydrogenotrophic methanogenesis (> 30 cm b.s.f., 14C-bicarbonate radiotracer incubation) was determined in two gravity cores at selected sites (78 and 407 m). Furthermore, stimulation (methanol addition) and inhibition (molybdate addition) experiments were carried out to investigate the relationship between sulfate reduction and methanogenesis.Highest rates of methanogenesis and sulfate reduction in the surface sediments, integrated over 0-25 cm b.s.f., were observed on the shelf (70-253 m, 0.06-0.1 and 0.5-4.7 mmol m-2 d-1, respectively), while lowest rates were discovered at the deepest site (1024 m, 0.03 and 0.2 mmol m-2 d-1, respectively). The addition of methanol resulted in significantly higher surface methanogenesis activity, suggesting that the process was mostly based on non-competitive substrates - i.e., substrates not used by sulfate reducers. In the deeper sediment horizons, where competition was probably relieved due to the decrease of sulfate, the usage of competitive substrates was confirmed by the detection of hydrogenotrophic activity in the sulfate-depleted zone at the shallow shelf station (70 m).Surface methanogenesis appeared to be correlated to the availability of labile organic matter (C / N ratio) and organic carbon degradation (DIC production

  16. Female genital mutilation in African and African American women's literature

    Directory of Open Access Journals (Sweden)

    Darja Marinšek

    2007-12-01

    Full Text Available The article builds on the existing dispute between African and African American women writers on the competence of writing about female genital mutilation (FGM, and tries to determine the existence and nature of the differences between the writings of these two groups. The author uses comparative analysis of two popular African and African American novels, comparing their ways of describing FGM, its causes and consequences, the level ob objectivity and the style of the narrations.This is followed by a discussion on the reasons for such differences, incorporating a larger circle of both African and African American women authors, at the same time analysing the deviance within the two groups. While the differences between African American writers are not that great, as they mostly fail to present the issue from different points of view, which is often the result of their lack of direct knowledge of the topic, African authors' writing is in itself discovered to be ambivalent and not at all invariable. The reasons for such ambivalence are then discussed in greater context, focusing on the effect of the authors' personal contact with circumcision as well as their knowledge and acceptance of Western values. The author concludes by establishing the African ambivalent attitude towards FGM, which includes different aspects of the issue, as the most significant difference between their and African American writers' description of this practice.

  17. Dynamic modeling and mobility analysis of the transforming roving-rolling explorer (TRREx) as it Traverses Rugged Martian Terrain

    Science.gov (United States)

    Edwin, Lionel E.; Mazzoleni, Andre P.

    2016-03-01

    All planetary surface exploration missions thus far have employed traditional rovers with a rocker-bogie suspension. These rovers can navigate moderately rough and flat terrain, but are not designed to traverse rugged terrain with steep slopes. The fact is, however, that the most scientifically interesting missions require exploration platforms with capabilities for navigating such types of rugged terrain. This issue motivates the development of new kinds of rovers that take advantage of the latest advances in robotic technologies to traverse rugged terrain efficiently. This work analyzes one such rover concept called the Transforming Roving-Rolling Explorer (TRREx) that is principally aimed at addressing the above issue. Biologically inspired by the way the armadillo curls up into a ball when threatened, and the way the golden wheel spider uses the dynamic advantages of a sphere to roll down hills when escaping danger, the TRREx rover can traverse like a traditional 6-wheeled rover over conventional terrain, but can also transform itself into a sphere, when necessary, to travel down steep inclines, or navigate rough terrain. This paper investigates the mobility of the TRREx when it is in its rolling mode, i.e. when it is a sphere and can steer itself through actuations that shift its center of mass to achieve the desired direction of roll. A mathematical model describing the dynamics of the rover in this spherical configuration is presented, and actuated rolling is demonstrated through computer simulation. Parametric analyzes that investigate the rover's mobility as a function of its design parameters are also presented. This work highlights the contribution of the spherical rolling mode to the enhanced mobility of the TRREx rover and how it could enable challenging surface exploration missions in the future.

  18. Transient-field strength measurements for 52Cr traversing Fe hosts at high velocity and polarization transfer mechanisms

    International Nuclear Information System (INIS)

    Transient-field strengths were measured for 52Cr ions traversing polarized Fe hosts at velocities up to 12v>=o (v>=o = c/137 = Bohr velocity). The results are compared with predictions of various transient field parametrizations and discussed in terms of possible mechanisms by which polarization might be transferred from the Fe host to inner vacancies of the moving Cr ions. The g-factor of the first 2+ state of 52Cr was also measured by the transient field technique and found to be in accord with shell-model calculations

  19. Leadership in the African context

    Directory of Open Access Journals (Sweden)

    M. Masango

    2002-08-01

    Full Text Available The Western world has always viewed the African continent as plagued by corruption; dictatorship; military coups; rebellious leaders; greediness; misuse of power; and incompetent, politically unstable leaders - in effect, suspicious leaders who undermine their own democracies. This paper analyzes African leadership and its impact by concentrating on three historical eras, namely; the African Religious era; the Christian era, and the era of Globalization. These affected African leadership. In addition, many brilliant minds left the continent in search of greener pastures. A review of these three eras will help us understand how leadership shifted from African values into Western concepts. The role of missionaries lead African people to live with both an African and a Western concept of life. In spite of the above problems, our past leaders did their best in addressing the difficulties they faced during the three eras. African concepts of leadership were often regarded as barbaric and uncultured. Structures were evaluated by Western standards. Due to globalisation, African leaders, through programmes like NEPAD, are going back to basics, drawing on African concepts of unity among its leadership. Effectiveness or life-giving leadership is emerging and empowering villagers/communities in the continent. This type of leadership is innovative and has brought new hope for the continent.

  20. The genetic structure and history of Africans and African Americans

    OpenAIRE

    Tishkoff, Sarah A; Reed, Floyd A; Friedlaender, Françoise R; Ehret, Christopher; Ranciaro, Alessia; Froment, Alain; Hirbo, Jibril B.; Awomoyi, Agnes A; Bodo, Jean-Marie; Doumbo, Ogobara; Ibrahim, Muntaser; Juma, Abdalla T; Kotze, Maritha J.; Lema, Godfrey; Moore, Jason H.

    2009-01-01

    Africa is the source of all modern humans, but characterization of genetic variation and of relationships among populations across the continent has been enigmatic. We studied 121 African populations, four African American populations, and 60 non-African populations for patterns of variation at 1327 nuclear microsatellite and insertion/deletion markers. We identified 14 ancestral population clusters in Africa that correlate with self-described ethnicity and shared cultural and/or linguistic p...

  1. Anti-trypanosomal activity of 1,2,3,4,6-penta-O-galloyl-? -D-glucose isolated from Plectranthus barbatus Andrews (Lamiaceae)

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Roberta T. dos; Hiramoto, Liliane L.; Lago, Joao Henrique G.; Sartorelli, Patricia [Universidade Federal de Sao Paulo (UNIFESP), Diadema, SP (Brazil). Inst. de Ciencias Ambientais, Quimicas e Farmaceuticas; Tempone, Andre G.; Pinto, Erika G. [Instituto Adolfo Lutz, Sao Paulo, SP (Brazil). Dept. de Parasitologia; Lorenzi, Harri, E-mail: psartorelli@unifesp.br [Instituto Plantarum de Estudos da Flora, Nova Odessa, SP (Brazil)

    2012-07-01

    MeOH extract from the leaves of Plectranthus barbatus Andrews (Lamiaceae), showed in vitro anti-trypanosomal activity. The bioassay-guided fractionation resulted in the isolation of a gallic acid derivative, identified as 1,2,3,4,6-penta-O-galloyl-{beta}-D-glucose (PGG), after thorough NMR and MS spectral analysis. Finally, this compound was tested against trypomastigote forms of T. cruzi and displayed an EC{sub 50} value of 67 {mu}M, at least 6.6-fold more effective than the standard drug benznidazole. This is the first occurrence of PGG in the Plectranthus genus and the first anti-parasitic activity described for PGG in the literature (author)

  2. Anti-trypanosomal activity of 1,2,3,4,6-penta-O-galloyl-β -D-glucose isolated from Plectranthus barbatus Andrews (Lamiaceae

    Directory of Open Access Journals (Sweden)

    Roberta T. dos Santos

    2012-01-01

    Full Text Available MeOH extract from the leaves of Plectranthus barbatus Andrews (Lamiaceae, showed in vitro anti-trypanosomal activity. The bioassay-guided fractionation resulted in the isolation of a gallic acid derivative, identified as 1,2,3,4,6-penta-O-galloyl-β-D-glucose (PGG, after thorough NMR and MS spectral analysis. Finally, this compound was tested against trypomastigote forms of T. cruzi and displayed an EC50 value of 67 µM, at least 6.6-fold more effective than the standard drug benznidazole. This is the first occurrence of PGG in the Plectranthus genus and the first anti-parasitic activity described for PGG in the literature.

  3. Steps to African Development

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The development of Africa is vital to the world’s sustainable development.However,African countries still face key challenges in achieving the meaningful expansion of their economies.At the High-Level Symposium on China-Africa Investment Cooperation in Xiamen,southeast China’s Fujian Province,held from September 8 to 10,Chen Deming,Minister of Commerce of China,elaborates on these challenges and sees

  4. Determination of the field dependence of the intergranular critical current in a YBCO tube by horizontal traversals

    Science.gov (United States)

    Çelebi, S.; LeBlanc, M. A. R.

    2006-12-01

    The magnetic flux density in the cavity of a sintered tube of Yttrium Barium Copper Oxide (YBCO) is measured as a function of H∥, the axial magnetic field impressed and removed after zero field cooling (ZFC). We note that, in a short thick-walled hollow cylinder of a weak-linked polycrystalline high- Tc superconductor, the magnetic field in the cavity of the tube, Hz hole , rises above the applied field H∥ when it is initially increasing. Consequently the standard approach to determine the critical current density from an ascending sweep of H∥ alone, or a descending sweep alone cannot be exploited. However the field dependence of the intergranular critical current density Jcm can be reliably obtained from the horizontal traversals of Hz hole vs H∥. Comparison of the experimental data with model calculations for the horizontal traversals of the hysteresis curves show that the intergranular critical current density in the YBCO tube has a Kim-like field dependence. The magnetization of the grains has a significant influence on the flux density in the cavity of the tube.

  5. Variability of 10Be and δ18O in snow pits from Greenland and a surface traverse from Antarctica

    International Nuclear Information System (INIS)

    To examine temporal variability of 10Be in glacial ice, we sampled snow to a depth of 160 cm at the NEEM (North Greenland Eemian Ice Drilling) drilling site in Greenland. The samples span three years between the summers of 2006 and 2009. At the same time, spatial variability of 10Be in glacial ice was explored through collection of the upper ∼5 cm of surface snow in Antarctica during part of the Swedish–Japanese traverse from Svea to Syowa station during the austral summer in 2007–2008. The results of the Greenlandic 10Be snow suggested variable concentrations that apparently do not clearly reflect the seasonal change as indicated by the δ18O data. The 10Be concentration variability most likely reflects also effects of aerosol loading and deposition pathways, possibly in combination with post-depositional processes. The Antarctic traverse data expose a negative correlation between 10Be and δ18O, while there are weaker but still significant correlations to altitude and distance to the coast (approximated by the distance to the 70th latitude). These relationships indicate that geographical factors, mainly the proximity to the coast, may strongly affect 10Be concentrations in snow in Queen Maud Land, Antarctica.

  6. Protein: CAD [Trypanosomes Database

    Lifescience Database Archive (English)

    Full Text Available CAD carbamoyl-phosphate synthetase 2, aspartate transcarbamylase, and dihydroorotaseCAD trifunct ... ional protein carbamoylphosphate synthetase 2/aspartate transcarb ... amylase/dihydroorotasemultifunctional protein ... CAD H.sapiens 47458828 18105007 790 P27708 CAD_(ge ...

  7. Expression and extracellular release of a functional anti-trypanosome Nanobody® in Sodalis glossinidius, a bacterial symbiont of the tsetse fly

    Directory of Open Access Journals (Sweden)

    De Vooght Linda

    2012-02-01

    Full Text Available Abstract Background Sodalis glossinidius, a gram-negative bacterial endosymbiont of the tsetse fly, has been proposed as a potential in vivo drug delivery vehicle to control trypanosome parasite development in the fly, an approach known as paratransgenesis. Despite this interest of S. glossinidius as a paratransgenic platform organism in tsetse flies, few potential effector molecules have been identified so far and to date none of these molecules have been successfully expressed in this bacterium. Results In this study, S. glossinidius was transformed to express a single domain antibody, (Nanobody® Nb_An33, that efficiently targets conserved cryptic epitopes of the variant surface glycoprotein (VSG of the parasite Trypanosoma brucei. Next, we analyzed the capability of two predicted secretion signals to direct the extracellular delivery of significant levels of active Nb_An33. We show that the pelB leader peptide was successful in directing the export of fully functional Nb_An33 to the periplasm of S. glossinidius resulting in significant levels of extracellular release. Finally, S. glossinidius expressing pelBNb_An33 exhibited no significant reduction in terms of fitness, determined by in vitro growth kinetics, compared to the wild-type strain. Conclusions These data are the first demonstration of the expression and extracellular release of functional trypanosome-interfering Nanobodies® in S. glossinidius. Furthermore, Sodalis strains that efficiently released the effector protein were not affected in their growth, suggesting that they may be competitive with endogenous microbiota in the midgut environment of the tsetse fly. Collectively, these data reinforce the notion for the potential of S. glossinidius to be developed into a paratransgenic platform organism.

  8. Repertoire, genealogy and genomic organization of cruzipain and homologous genes in Trypanosoma cruzi, T. cruzi-like and other trypanosome species.

    Directory of Open Access Journals (Sweden)

    Luciana Lima

    Full Text Available Trypanosoma cruzi, the agent of Chagas disease, is a complex of genetically diverse isolates highly phylogenetically related to T. cruzi-like species, Trypanosoma cruzi marinkellei and Trypanosoma dionisii, all sharing morphology of blood and culture forms and development within cells. However, they differ in hosts, vectors and pathogenicity: T. cruzi is a human pathogen infective to virtually all mammals whilst the other two species are non-pathogenic and bat restricted. Previous studies suggest that variations in expression levels and genetic diversity of cruzipain, the major isoform of cathepsin L-like (CATL enzymes of T. cruzi, correlate with levels of cellular invasion, differentiation, virulence and pathogenicity of distinct strains. In this study, we compared 80 sequences of genes encoding cruzipain from 25 T. cruzi isolates representative of all discrete typing units (DTUs TcI-TcVI and the new genotype Tcbat and 10 sequences of homologous genes from other species. The catalytic domain repertoires diverged according to DTUs and trypanosome species. Relatively homogeneous sequences are found within and among isolates of the same DTU except TcV and TcVI, which displayed sequences unique or identical to those of TcII and TcIII, supporting their origin from the hybridization between these two DTUs. In network genealogies, sequences from T. cruzi clustered tightly together and closer to T. c. marinkellei than to T. dionisii and largely differed from homologues of T. rangeli and T. b. brucei. Here, analysis of isolates representative of the overall biological and genetic diversity of T. cruzi and closest T. cruzi-like species evidenced DTU- and species-specific polymorphisms corroborating phylogenetic relationships inferred with other genes. Comparison of both phylogenetically close and distant trypanosomes is valuable to understand host-parasite interactions, virulence and pathogenicity. Our findings corroborate cruzipain as valuable target

  9. Biofuels: The African experience

    Energy Technology Data Exchange (ETDEWEB)

    Carrillo, L.A.; Nkolo, M. [German Agency for Technical Cooperation GTZ, Delegation Regionale des Eaux et Forets, Bertoua (Cameroon)

    2009-07-01

    In July 2006, the African Non-Petroleum Producers Association was formed in Senegal, Africa to develop alternative energy sources. It involved 13 of Africa's poorest nations, who joined forces to become global suppliers of biofuels, and some have set mandatory mixing of ethanol into gasoline. Although several biofuel production projects have been launched in western Africa, many of the new projects and plantations have not yet reached maturity due to the time lag between plantation and full-scale production, which is about 6 years. Major projects that could be producing significant quantities of biofuels in the next few years are not yet reflected in production statistics. Although ethanol is not yet being produced in large quantities in Africa, short-term opportunities exist. Countries in the South African Development Community are using molasses from the sugar can industry to produce ethanol. Biodiesel is also not currently produced on a significant scale in western Africa, but several other countries are gaining experience with cotton and palm oil resources, and Jatropha. Biomass residue also represents a large potential for all African countries involved in timber production. Unlike biodiesel production, land use conflicts are not an issue with biomass residue production.

  10. Diversity among African pygmies.

    Directory of Open Access Journals (Sweden)

    Fernando V Ramírez Rozzi

    Full Text Available Although dissimilarities in cranial and post-cranial morphology among African pygmies groups have been recognized, comparative studies on skull morphology usually pull all pygmies together assuming that morphological characters are similar among them and different with respect to other populations. The main aim of this study is to compare cranial morphology between African pygmies and non-pygmies populations from Equatorial Africa derived from both the Eastern and the Western regions in order to test if the greatest morphological difference is obtained in the comparison between pygmies and non-pygmies. Thirty three-dimensional (3D landmarks registered with Microscribe in four cranial samples (Western and Eastern pygmies and non-pygmies were obtained. Multivariate analysis (generalized Procrustes analysis, Mahalanobis distances, multivariate regression and complementary dimensions of size were evaluated with ANOVA and post hoc LSD. Results suggest that important cranial shape differentiation does occur between pygmies and non-pygmies but also between Eastern and Western populations and that size changes and allometries do not affect similarly Eastern and Western pygmies. Therefore, our findings raise serious doubt about the fact to consider African pygmies as a homogenous group in studies on skull morphology. Differences in cranial morphology among pygmies would suggest differentiation after divergence. Although not directly related to skull differentiation, the diversity among pygmies would probably suggest that the process responsible for reduced stature occurred after the split of the ancestors of modern Eastern and Western pygmies.

  11. Institution Building for African Regionalism

    OpenAIRE

    Khadiagala, Gilbert M.

    2011-01-01

    Since the 1960s, African states have embraced regional integration as a vital mechanism for political cooperation and for pooling resources to overcome problems of small and fragmented economies. In building meaningful institutions for regionalism, however, Africans have faced the challenges of reconciling the diversities of culture, geography, and politics. As a result, African regional institutions are characterized by multiple and competing mandates and weak institutionalization. This stud...

  12. Evaluation of different primers and DNA preparations for molecular diagnosis of human African Trypanosomosis

    International Nuclear Information System (INIS)

    This study was aimed at improving the diagnosis of Human African Trypanosomosis (HAT or sleeping sickness). We used the PCR on blood samples to compare two different methods of extraction/purification of DNA (chelex and DNA easy), and several PCR techniques (TBR 1-2, TgsGP, ESAG 6-7). The comparisons related to subjects taken at the time of medical surveillance in the mid-west of Ivory Coast and Benin: patients (Trypanosomes seen by parasitological tests), subjects with positive serologic tests but negative with parasitological tests (called sero-positives), negative subjects in serology and parasitology, and healthy volunteers living in Europe. The best combination was TBR used with Chelex. Under these conditions, the PCR test is simple, easily usable in a tropical laboratory, more sensitive than the parasitological examinations, and could help with the early detection of the cases, the decision to treat a patient, and with the post-therapeutic follow-up to detect cases of relapse. However, the limits of specificity and its high cost still restrict its use at the research laboratories

  13. African-Americans and Heart Disease, Stroke

    Science.gov (United States)

    ... Pressure High Blood Pressure Tools & Resources Stroke More African-Americans and Heart Disease, Stroke Updated:Apr 18, ... of getting those diseases are even higher for African-Americans. The good news is, African-Americans can ...

  14. Chronic Liver Disease and African Americans

    Science.gov (United States)

    ... American > Chronic Liver Disease Chronic Liver Disease and African Americans Among African Americans, chronic liver disease is a ... white women. At a glance – Cancer Rates for African Americans (2008-2012) Cancer Incidence Rates per 100,000 – ...

  15. The African Diaspora, Civil Society and African Integration

    DEFF Research Database (Denmark)

    Opoku-Mensah, Paul Yaw

    This paper, a work-in-progress, makes a contribution to the discussions on the appropriate modalities for incorporating the African diaspora in the African integration project.  It argues that the most appropriate entry points for incorporating the African diaspora into the integration project...... might not, necessarily, be in the formal political structures, although this is important. To the contrary, the most effective and sustainable might be within civil society---that is the links between the peoples and organizations of Africa and the diaspora. Using the case of the African academy-- as an...... institution of civil society--- the paper outlines a conceptual framework for incorporating the diaspora into the African integration project....

  16. Phytogeography of African Commelinaceae

    Directory of Open Access Journals (Sweden)

    R. B. Faden

    1983-12-01

    Full Text Available Africa (including Madagascar has nearly twice as many species of Commelinaceae as any other continent (approximately 270 species, or about 40% of the total in the family. Of the 17 genera which are native, seven (Anthericopsis, Coleotrype, Palisota, Polyspatha, Pseudoparis, Stanfieldiella and  Triceratella are endemic, the highest percentage generic endemism of any continent. Within Africa gcneric diversity is slightly higher in western than in eastern tropical floras. Species richness, however, is greatest in eastern Africa, mainly due to a high diversity of species of Commelina and Aneilema. Africa shares more genera with Asia (nine than with any other continent. Only one African genus, Buforrestia, is neither endemic nor shared with Asia. Its western African/northeastern South American distribution is unique in the family. Besides Buforrestia, only five other genera of Commelinaceae (out of a total of 50 in the family, occur in both the Old and New Worlds. These genera.  Aneilema, Commelina, Floscopa, Murdannia and  Pollia are all very widespread in the Old World, occurring in Australia and Asia in addition to Africa (both continental and Madagascar. Madagascar is relatively poor in species (31. but these include the endemic Madagascan genus Pseudoparis, the sole African species of Rhopalephora, and the largest number of species of the Afro-Malagasy endemic genus Coleotrype. The high rate of generic endemism of Commelinaceae in Africa probably indicates that Africa was one of the ancient centres of diversity for the family. The high species diversity is more likely due to relatively recent radiations by genera pre-adapted to survival in non-forest habitats. The occurrence of only a small number of genera on both sides of the Atlantic suggests that the Commelinaceae have been evolving independently in the eastern and western hemispheres for a long period.

  17. Booster for African Economy

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    China’s investment is fueling African growth SINCE 2000,driven by the Forum on China-Africa Cooperation,China’s foreign direct investment(FDI) in Africa has been growing rapidly.In the face of the global financial crisis,which led to global FDI flows falling,China’s investment in Africa has been on a steady, upbeat rise without any interruption.In 2009,China’s direct investment in Africa reached $1.44 billion,of which nonfinancial direct investment soared by 55.4 percent from the previous year.Africa

  18. African Conservation Tillage Network Website

    OpenAIRE

    African Conservation Tillage Network (ACT)

    2009-01-01

    Metadata only record Maintained by the African Conservation Tillage Network (ACT), this website provides information on Conservation Agriculture in an African context and gathered by stakeholders (NGOs) native to the continent. Resources on projects, practices, reports, and training courses are provided.

  19. A Call to African Unity

    DEFF Research Database (Denmark)

    Muchie, Mammo

    This month's paper, written by Professor Mammo Muchie, examines the necessity for a pan-African monetary union.  Professor Muchie argues for the "the creation of a unified African strategy and unified approach to dealing with the outside donor world by neutralising the poison of money as honey th...

  20. African Diaspora Associations in Denmark

    DEFF Research Database (Denmark)

    Vammen, Ida Marie; Trans, Lars Ove

    2011-01-01

    Since the early 1990s, an increasing number of African migrants have come to Denmark, where they have formed a large number of migrant associations. This chapter presents selected findings from a comprehensive survey of African diaspora associations in Denmark and focuses specifically on their...

  1. Large diameter urban gas pipeline in Vancouver, Canada traversing environmentally sensitive areas and very weak marine clays

    International Nuclear Information System (INIS)

    The paper presents the unique geotechnical design and construction aspects of a 24.1 kilometer NPS 42 gas pipeline constructed through a developed urban area. The project involved a total of seven directionally drilled road and stream crossings, 41 horizontally bored road crossings and traversed 3.4 kilometers of very weak sensitive marine clays. The design anticipated that future road and canal expansion in the low lying areas underlain by weak compressible marine clays will result in settlements of the operating pipeline. Measures to ensure long term pipeline integrity under these difficult loading conditions are presented. The environmental considerations associated with the design and construction of this project were of paramount importance. The pipeline crossed several major salmon spawning and rearing areas with one stream crossing located immediately downstream from a major fish hatchery. Measures taken to minimize the environmental impact during construction and operation of this pipeline will also be presented in the paper

  2. A case study of the intraseasonal oscillation traversing the TOGA-COARE LSD. [large-scale domain

    Science.gov (United States)

    Vincent, Dayton G.; Schrage, Jon M.; Sliwinski, L. D.

    1993-01-01

    The paper presents examination of tree intraseasonal (30-60 day) oscillations (ISOs) that occurred during the southern summer season (December 1, 1985 - February 28, 1986) traversing the Large-Scale Domain (LSD) TOGA-COARE, the region which also plays an important role in ENSO, Australian monsoon, and extratropical circulations. Data presented include Hovmoeller diagrams of 5-day running means of 250-mb velocity potential anomalies and OLR anomalies; graphs of five-day running means of OLR in precipitable water (W) per sq m, averaged over 10 x 10 deg boxes centered on 5 S and (1) 145 E, (2) 155 E, (3) 165 E, and (4) 165 D, indicating the midpoint of each ISO; and vertical profiles of zonal wind in m/s averaged over the time period that each ISO spends in the 10 x 10 deg box centered at 5 S, and 175 E and 145 E.

  3. The generalized second law forbids singularity resolution, viable baby universes, traversable wormholes, warp drives, time machines, and negative mass objects

    CERN Document Server

    Wall, Aron C

    2013-01-01

    The generalized second law can be used to prove a singularity theorem, by generalizing the notion of a trapped surface to quantum situations. Like Penrose's original singularity theorem, it implies that spacetime is null geodesically incomplete inside black holes, and to the past of spatially infinite Friedmann--Robertson--Walker cosmologies. If space is finite instead, the generalized second law requires that there only be a finite amount of entropy producing processes in the past, unless there is a reversal of the arrow of time. In asymptotically flat spacetime, the generalized second law also rules out traversable wormholes, negative masses, and other forms of faster-than-light travel, as well as closed timelike curves. Furthermore it is impossible to form baby universes which eventually become independent of the mother universe, or to restart inflation. Since the semiclassical approximation is used only in regions with low curvature, it is argued that the results may hold in full quantum gravity. An intro...

  4. Non-ionizing radiofrequency electromagnetic waves traversing the head can be used to detect cerebrovascular autoregulation responses

    Science.gov (United States)

    Oziel, M.; Hjouj, M.; Gonzalez, C. A.; Lavee, J.; Rubinsky, B.

    2016-02-01

    Monitoring changes in non-ionizing radiofrequency electromagnetic waves as they traverse the brain can detect the effects of stimuli employed in cerebrovascular autoregulation (CVA) tests on the brain, without contact and in real time. CVA is a physiological phenomenon of importance to health, used for diagnosis of a number of diseases of the brain with a vascular component. The technology described here is being developed for use in diagnosis of injuries and diseases of the brain in rural and economically underdeveloped parts of the world. A group of nine subjects participated in this pilot clinical evaluation of the technology. Substantial research remains to be done on correlating the measurements with physiology and anatomy.

  5. Research and Implementation of SIP Traversal NAT%SIP中NAT穿透技术的研究及实现

    Institute of Scientific and Technical Information of China (English)

    韩小燕; 曾桂根; 李敏

    2011-01-01

    With the rapid development of data service, packet -based multimedia communication system standards are widely used in vidco conference and IP phone. VolP developed from new generation network which is one of the most representative and perspective application technologies. SIP as one of signal control protocols of VoIP has great growth potentialities. So in order to extend the development of VoIP service, solving the problem of SIP traversal well will be an important research topic. In this paper, propose a solution for SIP traversal NAT through NATs based on UDP protocol. Finally realize the program in the VC environment and give the test results.%随着IP数据业务的蓬勃发展,基于分组的多媒体通信系统标准被广泛运用于视频会议和IP电话中,VOIP是新一代网络时代发展起来的最具代表性和发展前途的应用技术之一,SIP作为VOIP中的一种信令控制协议,具有很大的增长潜力,但SIP协议在设计时没有考虑到实际网络中会部署很多的NAT,为了更好的推广VOIP业务的发展,解决好SIP穿越NAT的问题将是一个重大的研究课题.文中主要在基于UDP穿透技术的基础上为SIP中NAT穿透提出了一种解决方案.最终在VC环境下实现该方案并给出测试结果.

  6. Bioenergy and African transformation.

    Science.gov (United States)

    Lynd, Lee R; Sow, Mariam; Chimphango, Annie Fa; Cortez, Luis Ab; Brito Cruz, Carlos H; Elmissiry, Mosad; Laser, Mark; Mayaki, Ibrahim A; Moraes, Marcia Afd; Nogueira, Luiz Ah; Wolfaardt, Gideon M; Woods, Jeremy; van Zyl, Willem H

    2015-01-01

    Among the world's continents, Africa has the highest incidence of food insecurity and poverty and the highest rates of population growth. Yet Africa also has the most arable land, the lowest crop yields, and by far the most plentiful land resources relative to energy demand. It is thus of interest to examine the potential of expanded modern bioenergy production in Africa. Here we consider bioenergy as an enabler for development, and provide an overview of modern bioenergy technologies with a comment on application in an Africa context. Experience with bioenergy in Africa offers evidence of social benefits and also some important lessons. In Brazil, social development, agricultural development and food security, and bioenergy development have been synergistic rather than antagonistic. Realizing similar success in African countries will require clear vision, good governance, and adaptation of technologies, knowledge, and business models to myriad local circumstances. Strategies for integrated production of food crops, livestock, and bioenergy are potentially attractive and offer an alternative to an agricultural model featuring specialized land use. If done thoughtfully, there is considerable evidence that food security and economic development in Africa can be addressed more effectively with modern bioenergy than without it. Modern bioenergy can be an agent of African transformation, with potential social benefits accruing to multiple sectors and extending well beyond energy supply per se. Potential negative impacts also cut across sectors. Thus, institutionally inclusive multi-sector legislative structures will be more effective at maximizing the social benefits of bioenergy compared to institutionally exclusive, single-sector structures. PMID:25709714

  7. Court stories in selected African short narratives

    OpenAIRE

    E. Yewah

    1994-01-01

    This article attempts to cross-examine African Literature and African costumary, Islamic and inherited colonial laws. It opens a new topic in the study of African literature by showing how legal discourses are inscribed in certain African narratives and how these discourses link the narratives to the overall context of their production.

  8. 2002 Sino-African SHP Training Workshop

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The 2002 Sino-African SHP Training Workshop was held from 10 May to 18 June 2002 at Hangzhou Regional Center for Small Hydro Power(HRC). Attended altogether 9 participants from 5 African countries, i.e. Burundi, Nigeria, South African, Tanzania and Tunisia. This is the second training workshop on SHP that HRC conducted for African countries.

  9. Assimilation Differences among Africans in America.

    Science.gov (United States)

    Dodoo, F. Nii-Amoo

    1997-01-01

    Census data (1990) indicate that male African immigrants earn more than their Caribbean-born counterparts or native-born African Americans, but controlling for relevant earnings-related endowments erases the African advantage and elevates Caribbean earnings above those of the other groups. Also, African (but not Caribbean) university degree…

  10. Evaluation of the antigen ELISA as a tool for assessing the impact of tsetse control programmes on the incidence of trypanosome infections in livestock

    International Nuclear Information System (INIS)

    The objective of the present study was to determine the suitability of the antigen ELISA as a method for assessing the efficacy of a tsetse control programme, based on the use of traps and screens impregnated with Deltamethrine. The efficacy of a tsetse control programme can be measured by monitoring the tsetse density on the one hand and by monitoring the infection rate and packed red cell volume (PCV) level of cattle on the other hand. We have used both monitoring methods as reference points to evaluate the Ag-ELISA, by determining how results of the Ag-ELISA correlated with those of the two reference methods. The monitoring was carried out in 8 localities: 4 situated in the tsetse control area and 4 located in a region without tsetse control (untreated area). The results were collected over a 12-month-study period. In the Deltamethrine treated area the tsetse density was reduced by nearly 95% after one month of control and virtually no tsetse fly could be caught after 12 months of tsetse control. A similar tendency was observed for the trypanosome infection rate in cattle, which decreased from 6% to 2% in the treated area, but increased from 3% to 10% in the untreated area. At the beginning of the experiment, the average PCV values (29.4%) were identical for animals in the treated and the untreated areas. Following 12 months of tsetse control, the average PCV value of animals in the treated area was 4.7 percentage units higher than of animals in the untreated area. The study of antigenaemia covered the first three months of the experiment. The rate of antigen positivity did not seem to correlate with trypanosome infection rates in cattle, nor with tsetse fly densities. This may be attributed to the low sensitivity of the test, while the specificity as studied on sera from tsetse free areas was high (98%). The monitoring period using the Ag-ELISA should be extended to cover the entire 12-month-study period to verify the preliminary conclusion. In addition

  11. How student teachers understand African philosophy

    OpenAIRE

    Matsephe M. Letseka; Elza Venter

    2012-01-01

    The question ‘What constitutes African philosophy?’ was first raised with the publication of Placide Tempels’s seminal work Bantu philosophy in 1959. Tempels’s book inevitably elicited considerable critical response from African philosophers, which culminated in a wide range of publications such as Wiredu’s (1980) Philosophy and an African culture, Hountondji’s (1983) African philosophy: Myth and reality, Oruka’s (1990) Sage philosophy: Indigenous thinkers and modern debate on African philoso...

  12. Overview of 3 years of ChemCam' chemical compositions along the Curiosity's traverse at Gale Crater.

    Science.gov (United States)

    Cousin, Agnès; Wiens, Roger; Maurice, Sylvestre; Gasnault, Olivier

    2016-04-01

    Curiosity rover has been in Gale crater for more than3 years now. It drove ~12 km from its landing point up to the Bagnold Dunes. The ChemCam instrument is widely used to assess the chemistry of rocks and soils at the submillimeter scale. As of sol 1200, ChemCam sampled >1000 targets, corresponding to >300000 laser shots, >6000 images, and many passive spectra. The Bradbury landing site, a plain located at a distal portion of the alluvial fan from Peace Vallis, exposed several float rocks presenting igneous compositions ranging from mafic up to a trachytic end-member. These observations provided an important clue concerning the diversity of early Mars magmatism that was not previously recognized. More igneous float rocks have been observed all along the traverse, being more felsic closer to the landing site, and more mafic near the cratered unit, after the Kimberley formation. The Sheepbed area is essentially composed of mudstones that show a very homogeneous composition, close to the average Martian crust, providing evidence of aqueous episodes with little alteration in this area. ChemCam showed that the bedrock host experienced other diagenetic events with Mg- and Fe-rich clays in erosion-resistant raised ridges on one hand, and calcium sulfate veins on the other hand. The nearby Shaler fluvial sandstone outcrop, the first outcrop of potential deltaic foreset beds, shows K enrichment. This enrichment is also observed at the Kimberley formation (another drill site flanked by foreset beds), located 7 km SW of Shaler, with up to 5.3 wt % at the Mount Remarkable member. Conglomerates have been analyzed in detail all along the traverse as they represent a link between the source rocks and the finer-grained sediments such as the sandstones and mudstones. They have shown an average composition that is enriched in alkalis, Al, and Si compared to the average Martian crust, with a clear enrichment in K2O in the vicinity of the Kimberley formation. Enrichment in K2O at

  13. Proposing an International Collaboration on Lightweight Autonomous Vehicles to Conduct Scientific Traverses and Surveys over Antarctica and the Surrounding Sea Ice

    Science.gov (United States)

    Carsey, Frank; Behar, Alberto

    2004-01-01

    We have continued to develop a concept for use of autonomous rovers, originally developed for use in planetary exploration, in polar science on Earth; the concept was the subject of a workshop, and this report summarizes and extends that workshop. The workshop on Antarctic Autonomous Scientific Vehicles and Traverses met at the National Geographic Society on February 14 and 15, 2001 to discuss scientific objectives and benefits of the use of autonomous rovers. The participants enthusiastically viewed rovers as being uniquely valuable for such tasks as data taking on tedious or repetitive routes, traverses in polar night, difficult or hazardous routes, extremely remote regions, routes requiring only simple instrumentation, traverses that must be conducted at low speed, augments of manned traverses, and scientific procedures not compatible with human presence or combustion engines. The workshop has concluded that instrumented autonomous vehicles, of the type being developed for planetary exploration, have the potential to contribute significantly to the way science in conducted in Antarctica while also aiding planetary technology development, and engaging the public's interest. Specific objectives can be supported in understanding ice sheet mass balance, sea ice heat and momentum exchange, and surface air chemistry processes. In the interval since the workshop, we have concluded that organized program to employ such rovers to perform scientific tasks in the Fourth International Polar Year would serve the objectives of that program well.

  14. African Ethnobotany in the Americas

    OpenAIRE

    Zent, Egleé L

    2013-01-01

    Review of African Ethnobotany in the Americas. Edited by Robert Voeks and John Rashford. 2013. Springer. Pp. 429, 105 illustrations, 69 color illustrations. $49.95 (paperback). ISBN 978‐1461408352.

  15. Mental Health and African Americans

    Science.gov (United States)

    ... Program Grants Other Grants Planning and Evaluation Grantee Best Practices Black/African American Asthma Cancer Chronic Liver Disease Diabetes Heart Disease Hepatitis HIV/AIDS Immunizations Infant Heath & Mortality Mental Health Obesity Organ and Tissue Donation Stroke Stay Connected ...

  16. African Ethnobotany in the Americas

    Directory of Open Access Journals (Sweden)

    Egleé L. Zent

    2013-10-01

    Full Text Available Review of African Ethnobotany in the Americas. Edited by Robert Voeks and John Rashford. 2013. Springer. Pp. 429, 105 illustrations, 69 color illustrations. $49.95 (paperback. ISBN 978‐1461408352.

  17. A synopsis of South African psychology from apartheid to democracy.

    Science.gov (United States)

    Cooper, Saths

    2014-11-01

    In this concatenated overview, the development of psychology in South Africa is traced from its origins in the late 19th century to the present. The seminal influences on the science and practice of psychology of the racialized polity and the responses to the prevailing regimen are also explored. The significant events in the patinated layers of psychological discourse and consequent policies in these constrained circumstances are traversed. Despite the nonracial era occasioned by the formation of the Psychological Society of South Africa three months before the advent of democracy under Nelson Mandela in 1994, the profession of psychology remains demographically skewed. Nevertheless, psychology in the current democratic dispensation enjoys a high profile and is actively engaged in ongoing and reflexive self-examination to ensure that it is more accessible and truly serves humanity. If Africa is psychology's last frontier, the critical denouement of the various issues confronting psychology in the southern tip of the African continent will provide a positive growth path that is likely to merit attention beyond its borders. PMID:25486173

  18. Twin Sessions Through African Eyes

    Institute of Scientific and Technical Information of China (English)

    Ni Yanshuo

    2012-01-01

    Every year journalists from around China and the world flock to Beijing in March to cover the sessions of the National People's Congress (NPC) and the Chinese People's Political Consultative Conference (CPPCC), known as the lianghui, or twin sessions. With the deepening of Sino-African relations in the past decades, an increasing number of African journalists are involved in reporting China's lianghui to their audiences in Africa.

  19. The Good African Society Index

    OpenAIRE

    Ferdi Botha

    2014-01-01

    This paper constructs a Good Society Index for 45 African countries, termed the Good African Society Index (GASI). The GASI consists of nine main indexes: (i) economic sustainability, (ii) democracy and freedom, (iii) child well-being, (iv) environment and infrastructure, (v) safety and security, (vi) health and health systems, (vii) integrity and justice, (viii) education, and (xi) social sustainability and social cohesion. Each component is split into four sub-components for a total of 36 i...

  20. Training in African aquaculture development

    OpenAIRE

    Brummett, R. E.

    1994-01-01

    The article focuses on the types of training needed in African aquaculture development. The author suggested that rather than needing less training, extension agents and others who operate in the idiosyncratic world of the poor African farmer, need a far deeper understanding of fish culture (particularly the basics of pond dynamics and ecology) than do those who can take advantage of industrialized-country infrastructure.

  1. Depletion of the Trypanosome Pumilio domain protein PUF2 or of some other essential proteins causes transcriptome changes related to coding region length.

    Science.gov (United States)

    Jha, Bhaskar Anand; Fadda, Abeer; Merce, Clementine; Mugo, Elisha; Droll, Dorothea; Clayton, Christine

    2014-05-01

    Pumilio domain RNA-binding proteins are known mainly as posttranscriptional repressors of gene expression that reduce mRNA translation and stability. Trypanosoma brucei has 11 PUF proteins. We show here that PUF2 is in the cytosol, with roughly the same number of molecules per cell as there are mRNAs. Although PUF2 exhibits a low level of in vivo RNA binding, it is not associated with polysomes. PUF2 also decreased reporter mRNA levels in a tethering assay, consistent with a repressive role. Depletion of PUF2 inhibited growth of bloodstream-form trypanosomes, causing selective loss of mRNAs with long open reading frames and increases in mRNAs with shorter open reading frames. Reexamination of published RNASeq data revealed the same trend in cells depleted of some other proteins. We speculate that these length effects could be caused by inhibition of the elongation phase of transcription or by an influence of translation status or polysomal conformation on mRNA decay. PMID:24681684

  2. The use of an antigen-detection ELISA for the diagnosis of trypanosome infections in N'dama cattle in Gambia

    International Nuclear Information System (INIS)

    An antigen-detection enzyme-linked immunosorbent assay (Ag-ELISA) for the detection of circulating trypanosomal antigens was evaluated for use in the diagnosis of trypanosomiasis in N'dama cattle in Gambia. Initial evaluation was carried out in cattle kept in areas of low or high tsetse challenge. Overall, approximately 12% of samples were parasite, but 67% showed presence of circulating antigens. The overall apparent sensitivity of the Ag-ELISA was 75%. In a separate experiment, the effects of treatment of antigenaemic N'dama cattle on weight gain and packed cell volume (PCV) was determined in animals kept under low level natural tsetse challenge. No differences were found in PCVs between drug treated and untreated animals but there was a significant weight gain in the drug treated group. Comparison of the same parameters in cattle in which parasites were detected by buffy coat technique (BCT), cattle which were Ag-ELISA positive but BCT negative, and cattle which were Ag-ELISA negative and BCT negative revealed little differences in weight, but PCVs were significantly lower in animals with a patent parasitaemia. (author). 4 refs, 4 figs, 3 tabs

  3. SAGE 2014: Grain size variability across the Sunlight Absorption on the Greenland ice sheet Experiment (SAGE) traverse route

    Science.gov (United States)

    Courville, Z.; Polashenski, C.; Domine, F.; Bergin, M. H.; Chen, J.; Farnsworth, L.; Stwertka, C.; Stewart, M. C.; Dibb, J. E.

    2014-12-01

    In 2014, researchers from the US Army Corps of Engineers Cold Region Research and Engineering Laboratory, Dartmouth College, the University of New Hampshire, Georgia Tech, University of Wisconsin, University of Michigan, and NASA-Langley completed the second year of a ground-based traverse of the Greenland Ice Sheet. Samples from 67 locations were extracted from shallow snow pits and analyzed for trace elements, black carbon (see Polashenski et al. and Dibb et al. in session C004: Aerosols and the Cryosphere), and snow grain size (in terms of specific surface area) at depths comprising at least the previous year's worth of snow accumulation at each site. In addition, surface characteristics of the snow including albedo, surface roughness and meteorological forcing were determined. Here, we present the spatial distribution of grain size reported as specific surface area determined from field measurements using the Takuvik International Laboratory DUal Frequency Integrating Sphere for Snow Specific area measurement (DUFISSS) instrument and from laboratory-based stereology and micro-CT measurements from snow samples that were preserved and shipped back to the lab. Grain sizes from 2014 are compared to 2013 results at coincident locations and comparable depths, and compared to the intervening year's worth of meteorological data from Automated Weather Stations (AWSs) assembled by the SAGE field team at four locations along the 2013 and 2014 routes.

  4. Analysis of Double Meridian Distance for a Closed Traverse Area towards Developing a Contour Map and Land Title

    Directory of Open Access Journals (Sweden)

    T. U. Ganiron Jr

    2014-07-01

    Full Text Available This research aimed to analyze double meridian distance for a closed traverse area in developing a land title for a propose gymnasium in Qassim University. Theodolite, leveling rod and steel tape plays an important role in measuring elevations, bearings and distances of the boundaries of a lot. Contour map is necessary to determine the traces of level surfaces of successive elevation. This will enable to identify the type of contour map and type of contour lines necessary for this project. Corel draw software is used to draw contour map and guide to interpret the significance of the variables. It is essential to check the error of closure for interior angles and for both latitude and departure before applying the Double Meridian Distance (DMD method to obtain the total area of the lot. Technical descriptions of the land such as distance, bearing, boundaries and area are necessary to visualize the shape & exact location of the land. Developing a land title will be obtained using the technical descriptions of the lot in preparation for the type of gymnasium necessary for Qassim University.

  5. The New African Civil-Military Relations

    DEFF Research Database (Denmark)

    the lead author accorded the responsibility of organizing a Session on ACMR. From amongst some of the exciting Abstracts presented, authors submitted these as full chapters for this book which captures International African Studies Perspectives, managed by the African Public Policy & Research...... on the African continent to embark upon the New African Civil Military Relations (ACMR). In the last decade and half, the implosion of African states exposed to forces of democratization has escalated, manifest in Algeria, Egypt, Mali, Madagascar, Somalia, South Sudan, Central African Republic and...

  6. Disarmament: the African perspective

    International Nuclear Information System (INIS)

    Disarmament is now generally accepted as the process of reduction in the size of, and expenditures on, armed forces, the destruction or dismantling of weapons, whether deployed or stockpiled, the progressive elimination of the capacity to produce new weapons and the release and integration into civilian life of military personnel. To realize this objective, the nations of the world have been advocating such measures as the establishment of nuclear weapon-free zones, non-proliferation, limitation of the arms trade, reduction of military budgets, and confidence-building measures. To ensure general and complete elimination of arms, there has been widespread recognition of the need to link the disarmament process with other political as well as socio-economic problems of the world such as the need for security, good relations between states and development of a system of peaceful settlement of disputes. Other measures that have been considered to be relevant in boosting the disarmament process include the role of the general public in putting pressure on their respective governments with a view to accelerating and realizing disarmament objectives. Africans have presented to the world a strong case for global disarmament

  7. East African Rift

    Science.gov (United States)

    2008-01-01

    Places where the earth's crust has formed deep fissures and the plates have begun to move apart develop rift structures in which elongate blocks have subsided relative to the blocks on either side. The East African Rift is a world-famous example of such rifting. It is characterized by 1) topographic deep valleys in the rift zone, 2) sheer escarpments along the faulted walls of the rift zone, 3) a chain of lakes within the rift, most of the lakes highly saline due to evaporation in the hot temperatures characteristic of climates near the equator, 4) voluminous amounts of volcanic rocks that have flowed from faults along the sides of the rift, and 5) volcanic cones where magma flow was most intense. This example in Kenya displays most of these features near Lake Begoria. The image was acquired December 18, 2002, covers an area of 40.5 x 32 km, and is located at 0.1 degrees north latitude, 36.1 degrees east longitude. The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  8. Traversing probe system

    International Nuclear Information System (INIS)

    This invention comprises a rotatable annular probe-positioner which carries at least one radially disposed sensing probe, such as a Pitot tube having a right-angled tip. The positioner can be coaxially and rotatably mounted within a compressor casing or the like and then actuated to orient the sensing probe as required to make measurements at selected stations in the annulus between the positioner and compressor casing. The positioner can be actuated to (a) selectively move the probe along its own axis, (b) adjust the yaw angle of the right-angled probe tip, and (c) revolve the probe about the axis common to the positioner and casing. A cam plate engages a cam-follower portion of the probe and normally rotates with the positioner. The positioner includes a first-motor-driven ring gear which effects slidable movement of the probe by rotating the positioner at a time when an external pneumatic cylinder is actuated to engage the cam plate and hold it stationary. When the pneumatic cylinder is not actuated, this ring gear can be driven to revolve the positioner and thus the probe to a desired circumferential location about the above-mentioned common axis. A second motor-driven ring gear included in the positioner can be driven to rotate the probe about its axis, thus adjusting the yaw angle of the probe tip. The positioner can be used in highly corrosive atmosphere, such as gaseous uranium hexafluoride. 10 claims, 6 figures

  9. Traverser la surface

    OpenAIRE

    Morcrette, Quentin

    2015-01-01

    Cet article étudie, d’une façon diachronique, les relations existant entre référentiel cartographique et cartographie d’itinéraire, aux Etats-Unis et en France. A travers trois exemples dans chacune des nations concernées par l’étude, l’accent sera mis sur les différences sémiologiques, où, au contraire, sur les similitudes entre les deux types de cartes. Après avoir montré que carte d’itinéraire et référentiel cartographique appartiennent à deux catégories cartographiques différentes, nous a...

  10. Proust traverse le temps

    OpenAIRE

    Dejean, Alexandra

    2015-01-01

    Marcel Proust en 1900 © DR Une explication littéraire est-elle indispensable pour percevoir le degré de composition de l’œuvre ? A.C. À la parution, beaucoup de lecteurs ont dit : « C’est écrit au fil de la plume, ce sont des mémoires, du bavardage… ». Un bon lecteur comme Jacques Rivière, secrétaire général de La Nouvelle Revue française (NRF), a compris, lui, qu’au contraire ce livre était extrêmement composé. « Rien n’est là par hasard », disait Proust : si telle chose a lieu à tel moment,...

  11. A traversable wormhole

    CERN Document Server

    Krasnikov, S

    2000-01-01

    A class of static Lorentzian wormholes with arbitrarily wide throats is presented in which the source of the WEC violations required by the Einstein equations is the vacuum stress-energy of the neutrino, electromagnetic, or massless scalar field.

  12. The Graph Traversal Pattern

    OpenAIRE

    Rodriguez, Marko A.; Neubauer, Peter

    2010-01-01

    A graph is a structure composed of a set of vertices (i.e.nodes, dots) connected to one another by a set of edges (i.e.links, lines). The concept of a graph has been around since the late 19$^\\text{th}$ century, however, only in recent decades has there been a strong resurgence in both theoretical and applied graph research in mathematics, physics, and computer science. In applied computing, since the late 1960s, the interlinked table structure of the relational database has been the predomin...

  13. Dynamic Server-Based KML Code Generator Method for Level-of-Detail Traversal of Geospatial Data

    Science.gov (United States)

    Baxes, Gregory; Mixon, Brian; Linger, TIm

    2013-01-01

    Web-based geospatial client applications such as Google Earth and NASA World Wind must listen to data requests, access appropriate stored data, and compile a data response to the requesting client application. This process occurs repeatedly to support multiple client requests and application instances. Newer Web-based geospatial clients also provide user-interactive functionality that is dependent on fast and efficient server responses. With massively large datasets, server-client interaction can become severely impeded because the server must determine the best way to assemble data to meet the client applications request. In client applications such as Google Earth, the user interactively wanders through the data using visually guided panning and zooming actions. With these actions, the client application is continually issuing data requests to the server without knowledge of the server s data structure or extraction/assembly paradigm. A method for efficiently controlling the networked access of a Web-based geospatial browser to server-based datasets in particular, massively sized datasets has been developed. The method specifically uses the Keyhole Markup Language (KML), an Open Geospatial Consortium (OGS) standard used by Google Earth and other KML-compliant geospatial client applications. The innovation is based on establishing a dynamic cascading KML strategy that is initiated by a KML launch file provided by a data server host to a Google Earth or similar KMLcompliant geospatial client application user. Upon execution, the launch KML code issues a request for image data covering an initial geographic region. The server responds with the requested data along with subsequent dynamically generated KML code that directs the client application to make follow-on requests for higher level of detail (LOD) imagery to replace the initial imagery as the user navigates into the dataset. The approach provides an efficient data traversal path and mechanism that can be

  14. An Effective and Efficient MapReduce Algorithm for Computing BFS-Based Traversals of Large-Scale RDF Graphs

    Directory of Open Access Journals (Sweden)

    Alfredo Cuzzocrea

    2016-01-01

    Full Text Available Nowadays, a leading instance of big data is represented by Web data that lead to the definition of so-called big Web data. Indeed, extending beyond to a large number of critical applications (e.g., Web advertisement, these data expose several characteristics that clearly adhere to the well-known 3V properties (i.e., volume, velocity, variety. Resource Description Framework (RDF is a significant formalism and language for the so-called Semantic Web, due to the fact that a very wide family of Web entities can be naturally modeled in a graph-shaped manner. In this context, RDF graphs play a first-class role, because they are widely used in the context of modern Web applications and systems, including the emerging context of social networks. When RDF graphs are defined on top of big (Web data, they lead to the so-called large-scale RDF graphs, which reasonably populate the next-generation Semantic Web. In order to process such kind of big data, MapReduce, an open source computational framework specifically tailored to big data processing, has emerged during the last years as the reference implementation for this critical setting. In line with this trend, in this paper, we present an approach for efficiently implementing traversals of large-scale RDF graphs over MapReduce that is based on the Breadth First Search (BFS strategy for visiting (RDF graphs to be decomposed and processed according to the MapReduce framework. We demonstrate how such implementation speeds-up the analysis of RDF graphs with respect to competitor approaches. Experimental results clearly support our contributions.

  15. Developing programs for african families, by african families

    DEFF Research Database (Denmark)

    Halliday, Jennifer A; Green, Julie; Mellor, David;

    2013-01-01

    Obesity is an emerging problem for African migrants in Australia, but few prevention programs incorporate their cultural beliefs and values. This study reports on the application of community capacity-building and empowerment principles in 4 workshops with Sudanese families in Australia. Workshop...... effects of physical activity and nutrition to improve health within communities while reducing intergenerational and gender role family conflicts.......Obesity is an emerging problem for African migrants in Australia, but few prevention programs incorporate their cultural beliefs and values. This study reports on the application of community capacity-building and empowerment principles in 4 workshops with Sudanese families in Australia. Workshop...

  16. Understanding the Rise of African Business

    DEFF Research Database (Denmark)

    Jorem, Kaja Tvedten; Jeppesen, Søren; Hansen, Michael W.

    latter suggests that profound improvements in African business performance are indeed under way: with the private sector playing a more important role as an engine of growth, with the rise of a capable African entrepreneurial class, and with the emergence of dynamic and competitive African enterprises......In light of recent enthusiasm over the African private sector, this paper reviews the existing empirical literature on successful African enterprises and proposes an analytical framework for understanding African firm success. Overall, it is argued that we need to develop an understanding of....... The paper proceeds to review the limited research on factors shaping the performance of African enterprises. It is observed that particularly the strategic component is often overlooked as is the role of internal capabilities and resources of African enterprises. Based on this identification of voids...

  17. African N Assessment

    Science.gov (United States)

    Bekunda, M.; Galford, G. L.; Hickman, J. E.; Palm, C.

    2011-12-01

    Africa's smallholder agricultural systems face unique challenges in planning for reducing poverty, concurrent with adaptation and mitigation to climate change. At continental level, policy seeks to promote a uniquely African Green Revolution to increase crop yields and food production, and improve local livelihoods. However, the consequences on the environment and climate are not clear; these pro-economic development measures should be linked to climate change adaptation and mitigation measures, and research is required to help achieve these policy proposals by identifying options, and testing impacts. In particular, increased nitrogen (N) inputs are essential for increasing food production in Africa, but are accompanied by inevitable increases in losses to the environment. These losses appear to be low at input levels promoted in agricultural development programs, while the increased N inputs both increase current food production and appear to reduce the vulnerability of food production to changes in climate. We present field and remote sensing evidence from Malawi that subsidizing improved seed and fertilizers increases resilience to drought without adding excess N to the environment. In Kenya, field research identified thresholds in N2O losses, where emissions are very low at fertilization rates of less than 200 kg ha-1. Village-scale models have identified potential inefficiencies in the food production process where the largest losses of reactive N occur, and which could be targeted to reduce the amount of N released to the environment. We further review some on-going research activities and progress in Africa that compare different methods of managing resources that target resilience in food production and adaptation to climate change, using nutrient N as an indicator, while evaluating the effects of these resource management practices on ecosystems and the environment.

  18. Spontaneous development of bilateral subdural hematomas in an infant with benign infantile hydrocephalus: color Doppler assessment of vessels traversing extra-axial spaces

    International Nuclear Information System (INIS)

    We present an infant with macrocrania, who initially demonstrated prominent extra-axial fluid collections on sonography of the brain, compatible with benign infantile hydrocephalus (BIH). Because of increasing macrocrania, a follow-up sonogram of the brain was performed; it revealed progressive enlargement of the extra-axial spaces, which now had echogenic debris. Color Doppler US showed bridging veins traversing these extra-axial spaces, so it was initially thought that these spaces were subarachnoid in nature (positive cortical vein sign). However, an arachnoid membrane was identified superior to the cortex, and there was compression of true cortical vessels beneath this dural membrane. An MRI of the brain showed the extra-axial spaces to represent bilateral subdural hematomas. The pathogenesis of spontaneous development of the subdural hematomas, in the setting of BIH, is discussed. We also emphasize that visualizing traversing bridging veins through extra-axial spaces does not necessarily imply that these spaces are subarachnoid in origin. (orig.)

  19. The transmission of African culture to children

    OpenAIRE

    Michele Tanon Lora

    2014-01-01

    African ancient traditions suffered a major historical change as a result of colonization. Several decades after decolonization and access to independence, what is the situation and place of the African culture in Africa and outside Africa? Does African culture perpetuate effectively today? What are the obstacles to the transmission of African culture to our children? What are the beliefs or elements that have influenced the transmission of our culture after the period of independence? Roughl...

  20. Translating Culture: Contemporary African American Poetry

    OpenAIRE

    Kristina Kočan Šalamon

    2015-01-01

    The paper interrogates cultural specifics of contemporary African American poetry and exhibits translation problems when translating this poetic work. African American writers have always included much of their cultural heritage in their writing and this is immediately noticed by a translator. The cultural elements, such as African American cuisine, attire and style in general, as well as spiritual and religious practices, often play a significant role for African American poets who are procl...

  1. Urbanism beyond Architecture : African cities as Infrastructure

    OpenAIRE

    Rao, Vyjayanthi; De Boeck, Filip; Simone, Abdou Maliq

    2009-01-01

    About African Cities Reader(A creation of the African Centre for Cities & Chimurenga Magazine ) In many senses African cities are amongst the most generative and vibrant places on the planet. Yet, we know next to nothing about what goes on in the places. Not that there is any shortage of caricature, hyperbole or opinion about what makes African cities such quintessential spaces of dystopia and atrophy. We believe that a range of interventions that seek to engage the shape-shifting essenc...

  2. High-throughput sequencing of partially edited trypanosome mRNAs reveals barriers to editing progression and evidence for alternative editing.

    Science.gov (United States)

    Simpson, Rachel M; Bruno, Andrew E; Bard, Jonathan E; Buck, Michael J; Read, Laurie K

    2016-05-01

    Uridine insertion/deletion RNA editing in kinetoplastids entails the addition and deletion of uridine residues throughout the length of mitochondrial transcripts to generate translatable mRNAs. This complex process requires the coordinated use of several multiprotein complexes as well as the sequential use of noncoding template RNAs called guide RNAs. The majority of steady-state mitochondrial mRNAs are partially edited and often contain regions of mis-editing, termed junctions, whose role is unclear. Here, we report a novel method for sequencing entire populations of pre-edited partially edited, and fully edited RNAs and analyzing editing characteristics across populations using a new bioinformatics tool, the Trypanosome RNA Editing Alignment Tool (TREAT). Using TREAT, we examined populations of two transcripts, RPS12 and ND7-5', in wild-typeTrypanosoma brucei We provide evidence that the majority of partially edited sequences contain junctions, that intrinsic pause sites arise during the progression of editing, and that the mechanisms that mediate pausing in the generation of canonical fully edited sequences are distinct from those that mediate the ends of junction regions. Furthermore, we identify alternatively edited sequences that constitute plausible alternative open reading frames and identify substantial variability in the 5' UTRs of both canonical and alternatively edited sequences. This work is the first to use high-throughput sequencing to examine full-length sequences of whole populations of partially edited transcripts. Our method is highly applicable to current questions in the RNA editing field, including defining mechanisms of action for editing factors and identifying potential alternatively edited sequences. PMID:26908922

  3. Flagellar membrane fusion and protein exchange in trypanosomes; a new form of cell-cell communication? [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Simon Imhof

    2016-04-01

    Full Text Available Diverse structures facilitate direct exchange of proteins between cells, including plasmadesmata in plants and tunnelling nanotubes in bacteria and higher eukaryotes.  Here we describe a new mechanism of protein transfer, flagellar membrane fusion, in the unicellular parasite Trypanosoma brucei. When fluorescently tagged trypanosomes were co-cultured, a small proportion of double-positive cells were observed. The formation of double-positive cells was dependent on the presence of extracellular calcium and was enhanced by placing cells in medium supplemented with fresh bovine serum. Time-lapse microscopy revealed that double-positive cells arose by bidirectional protein exchange in the absence of nuclear transfer.  Furthermore, super-resolution microscopy showed that this process occurred in ≤1 minute, the limit of temporal resolution in these experiments. Both cytoplasmic and membrane proteins could be transferred provided they gained access to the flagellum. Intriguingly, a component of the RNAi machinery (Argonaute was able to move between cells, raising the possibility that small interfering RNAs are transported as cargo. Transmission electron microscopy showed that shared flagella contained two axonemes and two paraflagellar rods bounded by a single membrane. In some cases flagellar fusion was partial and interactions between cells were transient. In other cases fusion occurred along the entire length of the flagellum, was stable for several hours and might be irreversible. Fusion did not appear to be deleterious for cell function: paired cells were motile and could give rise to progeny while fused. The motile flagella of unicellular organisms are related to the sensory cilia of higher eukaryotes, raising the possibility that protein transfer between cells via cilia or flagella occurs more widely in nature.

  4. Opa binding to cellular CD66 receptors mediates the transcellular traversal of Neisseria gonorrhoeae across polarized T84 epithelial cell monolayers.

    Science.gov (United States)

    Wang, J; Gray-Owen, S D; Knorre, A; Meyer, T F; Dehio, C

    1998-11-01

    We have analysed the capacity of the 11 phase-variable, opacity-associated (Opa) proteins encoded by Neisseria gonorrhoeae MS11 to mediate traversal across polarized monolayers of the human colonic carcinoma T84 cell line. Gonococci expressing either the heparan sulphate proteoglycan (HSPG) binding Opa protein (Opa50) or no Opa protein (Opa-) did not interact with the apical pole of T84 monolayers, whereas the 10 variant Opa proteins previously shown to bind CD66 receptors were found to mediate efficient gonococcal adherence and transepithelial traversal. Consistent with this, T84 cells were shown by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunoblotting to co-express CD66a (BGP), CD66c (NCA) and CD66e (CEA). The recruitment of CD66 receptors by Opa-expressing gonococci indicates their involvement in mediating adherence to the surface of T84 cells, and these bacterial interactions could be inhibited completely using polyclonal antibodies cross-reacting with all of the CD66 proteins co-expressed on T84 cells. Consistent results were obtained when Opa proteins were expressed in Escherichia coli, suggesting that the Opa-CD66 interaction is sufficient to mediate bacterial traversal. Transcytosis of Opa-expressing N. gonorrhoeae or E. coli did not disrupt the barrier function of infected monolayers, as indicated by a sustained transepithelial electrical resistance (TEER) throughout the course of infection, and confocal laser scanning and electron microscopy both suggest a transcellular rather than a paracellular route of traversal across the monolayers. Parallels between the results seen here and previous work done with organ cultures confirm that T84 monolayers provide a valid model for studying neisserial interactions with the mucosal surface, and suggest that CD66 receptors contribute to this process in vivo. PMID:9822830

  5. MORE CHINESE CARS ON AFRICAN ROADS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    China drives into the African vehicle market and meets the challenges head on with some advantages of its own High-quality but inexpensive Chinese automobiles have gradually won the confidence of the African market and are becoming a bright new link in Sino-African economic ties. On September 4, a total of 400 Polarsun minibuses, made in Shenyang, capital of northeast

  6. Engaging African Americans in Smoking Cessation Programs

    Science.gov (United States)

    Wallen, Jacqueline; Randolph, Suzanne; Carter-Pokras, Olivia; Feldman, Robert; Kanamori-Nishimura, Mariano

    2014-01-01

    Background: African Americans are disproportionately exposed to and targeted by prosmoking advertisements, particularly menthol cigarette ads. Though African Americans begin smoking later than whites, they are less likely to quit smoking than whites. Purpose: This study was designed to explore African American smoking cessation attitudes,…

  7. Characterization of the tensile properties of friction stir welded aluminum alloy joints based on axial force, traverse speed, and rotational speed

    Science.gov (United States)

    Panda, Biranchi; Garg, A.; Jian, Zhang; Heidarzadeh, Akbar; Gao, Liang

    2016-06-01

    Friction stir welding (FSW) process has gained attention in recent years because of its advantages over the conventional fusion welding process. These advantages include the absence of heat formation in the affected zone and the absence of large distortion, porosity, oxidation, and cracking. Experimental investigations are necessary to understand the physical behavior that causes the high tensile strength of welded joints of different metals and alloys. Existing literature indicates that tensile properties exhibit strong dependence on the rotational speed, traverse speed, and axial force of the tool that was used. Therefore, this study introduces the experimental procedure for measuring tensile properties, namely, ultimate tensile strength (UTS) and tensile elongation of the welded AA 7020 Al alloy. Experimental findings suggest that a welded part with high UTS can be achieved at a lower heat input compared with the high heat input condition. A numerical approach based on genetic programming is employed to produce the functional relationships between tensile properties and the three inputs (rotational speed, traverse speed, and axial force) of the FSW process. The formulated models were validated based on the experimental data, using the statistical metrics. The effect of the three inputs on the tensile properties was investigated using 2D and 3D analyses. A high UTS was achieved, including a rotational speed of 1050 r/min and traverse speed of 95 mm/min. The results also indicate that 8 kN axial force should be set prior to the FSW process.

  8. Research and Implementation of SIP Traverses NAT Based on SBC%基于 SBC的SIP穿越 NAT的研究与实现

    Institute of Scientific and Technical Information of China (English)

    王琰; 石伟芳

    2014-01-01

    NAT缓解了目前IP地址空间不足的问题,但它不能对应用层协议 SIP 中嵌套的 IP 地址和端口进行转换,而在 NGN网络中处于核心地位的 SIP 协议也不提供穿越 NAT 的功能。因此,实现 SIP 穿越 NAT显得尤为必要。文章通过对 NAT及SIP协议的分析,提出基于 SBC的SIP穿越NAT解决方案。%Currently, NAT relieves the problem of insufficient space of IP address .However, it can’ t translate IP and the port nested in the SIP , which is an application layer protocol .SIP protocol doesn't provide the function of NAT traverse .So it is very important to realize SIP to NAT traverse .This paper analyses the principle of the NAT and the SIP Protocol , puts forward a program that SIP traverses NAT based on SBC .

  9. How student teachers understand African philosophy

    Directory of Open Access Journals (Sweden)

    Matsephe M. Letseka

    2012-10-01

    Full Text Available The question ‘What constitutes African philosophy?’ was first raised with the publication of Placide Tempels’s seminal work Bantu philosophy in 1959. Tempels’s book inevitably elicited considerable critical response from African philosophers, which culminated in a wide range of publications such as Wiredu’s (1980 Philosophy and an African culture, Hountondji’s (1983 African philosophy: Myth and reality, Oruka’s (1990 Sage philosophy: Indigenous thinkers and modern debate on African philosophy, Shutte’s (1993 Philosophy for Africa, Masolo’s (1994 African philosophy in search of identity and Gyekye’s (1995 An essay of African philosophical thought: The Akan conceptual scheme. It has been over 60 years since the publication of Temples’s book and there continues to be serious debate about African philosophy. This article sought to contribute to the debate on the various conceptions of African philosophy, but with a focus on the challenges of teaching African philosophy to Philosophy of Education students at an open distance learning institution in South Africa. This article discussed the tendency amongst undergraduate Philosophy of Education students to conflate and reduce African philosophy to African cultures and traditions, and to the notion of ubuntu, and sought to understand the reasons for students’ inclination to treat African philosophy in this way. It examined students’ background knowledge of African philosophy, their critical thinking skills and whether their official study materials are selected and packaged in a manner that, in fact, adds to the challenges they face. Finally, the article explored the ways in which Philosophy of Education lecturers can adapt their pedagogy to provide students with a better understanding of African philosophy.

  10. Slurry wear characteristics of zinc-based alloys: Effects of sand content of slurry, silicon addition to alloy system and traversal distance

    Institute of Scientific and Technical Information of China (English)

    B.K. PRASAD; O.P. MODI

    2009-01-01

    This investigation deals with the observations pertaining to the effects of specimen and slurry compositions as well as traversal distance on the slurry wear response of a zinc-based alloy. The composition of the alloy was altered by adding 4% silicon to it. The slurry composition was varied through changing the concentration of the sand particles in the range of 0-60% that were suspended in the (liquid) electrolyte. The electrolyte contained 4 g sodium chloride and 5 mL concentrated sulphuric acid dissolved in 10 L of water. The slurry wear tests were conducted at a speed of 7.02 m/s over the traversal distance range of 15-500 km. The wear rate increased initially with traversal distance, attained a maximum and decreased thereafter irrespective of the specimen and test environment. However, the wear rate peaks were less prominent in the liquid plus sand environments than the liquid-only medium. Further, the wear rate peak in the liquid-only medium appeared at a shorter traversal distance than the one in the sand containing slurries. Addition of sand particles to the electrolyte reduced the wear rate of the samples to 5%-15% depending on the sand concentration of the slurry. Moreover, intermediate (40%) sand content led to a maximum wear rate when compared with in the liquid plus sand media. However, this maximum was still less than in the liquid-only medium. The silicon containing alloy suffered from higher wear rates than the silicon free alloy samples when tested in the liquid-only medium. On the contrary, the trend reversed in liquid plus 20% and 40% sand environments whereas a mixed response was noted in the slurry containing 60% sand. In the latter case, the presence of silicon proved deleterious initially while an opposite trend was observed at longer traversal distances. The wear response of the samples was discussed in terms of specific features of their microconstituents like silicon and the predominant material removal mechanism in a given set of

  11. Analyses of robotic traverses and sample sites in the Schrödinger basin for the HERACLES human-assisted sample return mission concept

    Science.gov (United States)

    Steenstra, Edgar S.; Martin, Dayl J. P.; McDonald, Francesca E.; Paisarnsombat, Sarinya; Venturino, Christian; O'Hara, Sean; Calzada-Diaz, Abigail; Bottoms, Shelby; Leader, Mark K.; Klaus, Kurt K.; van Westrenen, Wim; Needham, Debra H.; Kring, David A.

    2016-09-01

    The International Space Exploration Coordination Group (ISECG) developed an integrated Global Exploration Roadmap (GER) that outlines plans for human-assisted sample return from the lunar surface in ∼2024 and for human presence on the lunar surface in ∼2028. Previous studies have identified the Schrödinger basin, situated on the far side of the Moon, as a prime target for lunar science and exploration where a significant number of the scientific concepts reviewed by the National Research Council (NRC, 2007) can be addressed. In this study, two robotic mission traverses within the Schrödinger basin are proposed based on a 3 year mission plan in support of the HERACLES human-assisted sample return mission concept. A comprehensive set of modern remote sensing data (LROC imagery, LOLA topography, M3 and Clementine spectral data) has been integrated to provide high-resolution coverage of the traverses and to facilitate identification of specific sample localities. We also present a preliminary Concept of Operations (ConOps) study based on a set of notional rover capabilities and instrumental payload. An extended robotic mission to the Schrödinger basin will allow for significant sample return opportunities from multiple distinct geologic terrains and will address multiple high-priority NRC (2007) scientific objectives. Both traverses will offer the first opportunity to (i) sample pyroclastic material from the lunar farside, (ii) sample Schrödinger impact melt and test the lunar cataclysm hypothesis, (iii) sample deep crustal lithologies in an uplifted peak ring and test the lunar magma ocean hypothesis and (iv) explore the top of an impact melt sheet, enhancing our ability to interpret Apollo samples. The shorter traverse will provide the first opportunity to sample farside mare deposits, whereas the longer traverse has significant potential to collect SPA impact melt, which can be used to constrain the basin-forming epoch. These robotic missions will revalidate

  12. African women, literature, language and culture

    OpenAIRE

    Rosamond S. King

    2014-01-01

    This essay will link African women’s writing to culture, including literary culture and the politics of literature. It describes how African women’s literature can act as a mirror, reflecting African cultures to Africans, and how it can serve as a window and a door, revealing African cultures to those outside of them in whole or in part. It ends with a description of “communal agency,” an example of how scholarly writing can act as a door for both those who are and are not a part of a literat...

  13. P and S Waves Traversing Beneath Western Japan and the Shape of the Subducting Philippine Sea Plate

    Science.gov (United States)

    Kuge, K.; Fukuda, T.

    2011-12-01

    We show the characteristics of P and S waves traversing beneath western Japan, which can provide constraints on the shape of the subducting Philippine Sea plate. The subduction of the Philippine Sea plate causes megathrust earthquakes along the Nankai trough in western Japan. The complicated shape of the subducting plate can affect the spatial variation of the plate coupling as well as the recurrence of great interplate earthquakes. For slab earthquakes at depths of about 45 km in northwestern Shikoku, we observe two arrivals of P wave at the NIED Hi-net stations in the azimuth range from the north to the east. The apparent velocities are about 8 and 6.7 km/s, corresponding to P velocities in the mantle and crust, respectively. Dominant S waves propagate by apparent velocity of about 3.8 km/s, being S velocity in the crust. These observations are in agreement with those of Oda et al. (1990) and Ohkura (2000) using a smaller number of local stations. The P and S waves propagating at the slow apparent velocities can be modeled by horizontally layered structure if the earthquakes are located within a low-velocity layer spanning the stations. The thick low-velocity layer can be a stack of the continental crust of the Eurasian plate and the oceanic crust of the Philippine Sea plate subducting nearly subhorizontally (Oda et al., 1990; Ohkura, 2000). The P and S waves with the slow apparent velocities are observable at distances up to about 300 km. On the other hand, they are not observed or observable only at small distances in the western side of the epicenters. The spatial characteristics can be used to constrain the geometry of the low-velocity layer associated with the shape of the oceanic crust of the Philippine Sea plate. We observe two arrivals of P wave in the eastern side of the Kii Peninsula for slab earthquakes beneath Shikoku. Both apparent velocities are in a range of P velocity in the mantle. There appear two ray paths of P wave propagating in the mantle

  14. East African odontopygid millipedes 1

    DEFF Research Database (Denmark)

    Frederiksen, Sara B.; Enghoff, Henrik

    2012-01-01

    Five new species of the endemic East African genus Xystopyge are described: X. pelecys, X. frontieri, X. proplicatus, X. biacanthus, and X. zanzibarensis. Three are from the Eastern Arc Mountains, Tanzania, two are from the Usambara Mtns. and one is from the Uluguru Mtns. One further species is...

  15. Wellness among African American Counselors

    Science.gov (United States)

    Day-Vines, Norma L.; Holcomb-McCoy, Cheryl

    2007-01-01

    Although there are various definitions of wellness, few conceptual definitions have addressed the contextual dimensions of wellness relative to African American counselors. The authors present an overview of generic models of wellness, discuss factors that both inhibit and promote wellness, offer some culture-specific models of wellness, and…

  16. Quo vadis South African universities?

    OpenAIRE

    Johann RE lutjeharms

    2007-01-01

    The Economist has recently identified some specific factors that explain why European universities are not competing adequately with their American counterparts. These factors are used here to evaluate South African government policy for universities. It is demonstrated that this current policy is directly contrary to what is now internationally considered best for universities in a knowledge economy.

  17. Vitamin D and African Americans

    Science.gov (United States)

    Vitamin D insufficiency is more prevalent among African Americans than other Americans and, in North America, most young, healthy blacks do not achieve optimal 25-hydroxyvitamin D [25(OH)D] concentrations at any time of the year. This is primarily due to the fact that pigmentation reduces vitamin D...

  18. Rock Populations Along the Spirit Rover Traverse: Implications for the Timing and Amount of Gradation in Gusev Crater, Mars

    Science.gov (United States)

    Wilson, S. A.; Grant, J. A.; Ruff, S. W.; Golombek, M. P.

    2006-12-01

    The rock population in Gusev Crater was analyzed at 36 locations along ~4 km of the Spirit rover's traverse, including 27 across the plains and 9 from Husband Hill. Rocks located between 8 20 m from the rover with a long axis greater than 15 cm in diameter were measured using Pancam images taken at the end of rover drives. The Pancam images typically covered an azimuth wedge of approximately 45 degrees, resulting in an 80-100 m2 sampling area. Rock measurements made on the plains prior to reaching Husband Hill were associated with geomorphic surfaces dominated by crater rims, ejecta, or plains surfaces. The average number of rocks per square meter was 0.2 on ejecta, 0.3-0.5 on the plains and Husband Hill, and just over 0.5 on crater rims. The average axis of the measured rocks on all surfaces ranges between 22-29 cm (associated standard deviations were 8-18 cm). The size-frequency distribution of rocks on all surfaces display an exponential increase in number with decreasing size, but bedrock outcrops on Husband Hill result in a greater number of rocks larger than 50 cm in diameter relative to observations on the plains surfaces. The size-frequency distribution plot can be modified by cubing the rock diameters and multiplying by an assumed density (3000 kg/m3) to serve as a proxy for rock mass. The resulting mass-frequency distribution plot yields slopes of 0.9-1.2 for the plains and Husband Hill surfaces in Gusev, which are broadly consistent with those expected for surfaces modified by multiple impact fragmentation processes. This result, in concert with an absence of sorting or other evidence of modification by alternate processes (other than tens of centimeters of aeolian redistribution of fine sediments), confirms the dominant role of impact cratering in the modification of these surfaces since the Hesperian. Moreover, data from the Mini-TES instrument on the Spirit rover indicate some rocks on Husband Hill smaller than 50 cm in diameter are compositionally

  19. The UCAR Africa Initiative: Enabling African Solutions to African Needs

    Science.gov (United States)

    Pandya, R.; Bruintjes, R.; Foote, B.; Heck, S.; Hermann, S.; Hoswell, L.; Konate, M.; Kucera, P.; Laing, A.; Lamptey, B.; Moncrieff, M.; Ramamurthy, M.; Roberts, R.; Spangler, T.; Traoré, A.; Yoksas, T.; Warner, T.

    2007-12-01

    The University Corporation for Atmospheric Research (UCAR) Africa Initiative (AI) is a coordinated effort aimed at building sustainable partnerships between UCAR and African institutions in order to pursue research and applications for the benefit of the African people. The initiative is based on four fundamental operating principles, concisely summarized by the overall philosophy of enabling African solutions to African needs. The four principles are: • Collaborate with African institutions • Focus on institutional capacity building and research support • Explore science research themes critical to Africa and important for the world • Leverage the research infrastructure in UCAR to add value These principles are realized in a set of pilot activities, chosen for their high probability of short-term results and ability to set the stage for longer-term collaboration. The three pilot activities are listed below. 1. A modest radar network and data-distribution system in Mali and Burkina Faso, including a data-sharing MOU between the Mail and Burkina Faso Weather Services. 2. A partnership among UCAR, the Ghana Meteorological Agency, and the Ghana university community to develop an operational Weather Research and Forecasting (WRF) model for West Africa. The output is used by researchers and operational forecasters in Africa. Model output is also part of a demonstration project that aims to allow humanitarian agencies to share geo-referenced information in Africa via a web portal. 3. A workshop in Ouagadougou, Burkina Faso from April 2-6, 2007, with the theme Improving Lives by Understanding Weather. The workshop, co-organized with Programme SAAGA and the Commité Permanent Inter-Etats de Lutte Contre la Sécheresse dans le Sahel (CILSS), included over 80 participants from 18 countries, and produced a set of recommendations for continued collaboration. Our presentation will provide an update of these pilot activities and point to future directions. Recognizing

  20. Derivation of Upper Bounds on Optimization Time of Population-Based Evolutionary Algorithm on a Function with Fitness Plateaus Using Elitism Levels Traverse Mechanism

    CERN Document Server

    Ter-Sarkisov, Aram

    2012-01-01

    In this article we derive upper bounds on optimization time of the recombination algorithm solving a unimodal problem with plateaus of fitness using a tool we called Elitism Levels Traverse Mechanism. Our findings are asymptotically tight for different parameters of the algorithm and the problem, and we are able to recover some well-known bounds for test problems such as OneMax and Royal Roads. We also present find- ings on the limiting distribution of super-elite species in the population, something no-one seems to have done before in the EA community.

  1. 国际象棋马在棋盘中遍历的研究%The Horse of Chess in Chessboard Traverse Study

    Institute of Scientific and Technical Information of China (English)

    曾红

    2011-01-01

    The research,by adopting the deep traversal calculating method,is on the chess,particularlly on the knight's move without repeating its steps on chessboard,and works out more than one hundred thousand paths.%本文通过对国际象棋的马在不重复遍历整个棋盘的路径的研究,采用深度遍历算法,计算出十多万条路径。

  2. Water equivalent hydrogen estimates from the first 200 sols of Curiosity's traverse (Bradbury Landing to Yellowknife Bay): Results from the Dynamic Albedo of Neutrons (DAN) passive mode experiment

    Science.gov (United States)

    Tate, C. G.; Moersch, J.; Jun, I.; Ming, D. W.; Mitrofanov, I.; Litvak, M.; Behar, A.; Boynton, W. V.; Deflores, L.; Drake, D.; Ehresmann, B.; Fedosov, F.; Golovin, D.; Hardgrove, C.; Harshman, K.; Hassler, D. M.; Kozyrev, A. S.; Kuzmin, R.; Lisov, D.; Malakhov, A.; Milliken, R.; Mischna, M.; Mokrousov, M.; Nikiforov, S.; Sanin, A. B.; Starr, R.; Varenikov, A.; Vostrukhin, A.; Zeitlin, C.

    2015-12-01

    The Dynamic Albedo of Neutrons (DAN) experiment on the Mars Science Laboratory (MSL) rover Curiosity is designed to detect neutrons to determine hydrogen abundance within the subsurface of Mars (Mitrofanov, I.G. et al. [2012]. Space Sci. Rev. 170, 559-582. http://dx.doi.org/10.1007/s11214-012-9924-y; Litvak, M.L. et al. [2008]. Astrobiology 8, 605-613. http://dx.doi.org/10.1089/ast.2007.0157). While DAN has a pulsed neutron generator for active measurements, in passive mode it only measures the leakage spectrum of neutrons produced by the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) and Galactic Cosmic Rays (GCR). DAN passive measurements provide better spatial coverage than the active measurements because they can be acquired while the rover is moving. Here we compare DAN passive-mode data to models of the instrument's response to compositional differences in a homogeneous regolith in order to estimate the water equivalent hydrogen (WEH) content along the first 200 sols of Curiosity's traverse in Gale Crater, Mars. WEH content is shown to vary greatly along the traverse. These estimates range from 0.5 ± 0.1 wt.% to 3.9 ± 0.2 wt.% for fixed locations (usually overnight stops) investigated by the rover and 0.6 ± 0.2 wt.% to 7.6 ± 1.3 wt.% for areas that the rover has traversed while continuously acquiring DAN passive data between fixed locations. Estimates of WEH abundances at fixed locations based on passive mode data are in broad agreement with those estimated at the same locations using active mode data. Localized (meter-scale) anomalies in estimated WEH values from traverse measurements have no particular surface expression observable in co-located images. However at a much larger scale, the hummocky plains and bedded fractured units are shown to be distinct compositional units based on the hydrogen content derived from DAN passive measurements. DAN passive WEH estimates are also shown to be consistent with geologic models inferred from other

  3. The African Financial Development Gap

    OpenAIRE

    Allen, Franklin; Carletti, Elena; Cull, Robert; Qian, Jun; Senbet, Lemma

    2010-01-01

    Economic growth in Africa has long been disappointing. We document that the financial sectors of most sub-Saharan African countries remain significantly underdeveloped by the standards of other developing countries. We examine the factors that are associated with financial development in Africa and compare them with those in other developing countries. Population density appears to be considerably more important for banking sector development in Africa than elsewhere. Given the high costs of ...

  4. Recent growth in African cassava

    OpenAIRE

    Nweke, Felix; Haggblade, Steven; Zulu, Ballard

    2004-01-01

    According to the authors, "Cassava serves as a staple food for 200 million Africans, second only to maize in its calorie contribution. In response to a series of devastating attacks by cassava diseases and pests over the past several decades, the International Institute of Tropical Agriculture (IITA) and several national agricultural research services have launched successful cassava research programs... " This brief describes some of the programs, their impact and the drivers of change. It c...

  5. Financial Liberalization: The African Experience

    OpenAIRE

    Reinhart, Carmen; Tokatlidis, Ioannis

    2000-01-01

    Almost a decade after their initiation, financial reforms appear to have had little effect on the economies of Sub-Sahara Africa. Whether the blame is to fall on their initial design itself, or on the partial nature of their implementation, liberalization policies have not mobilized savings, deepened intermediation or raised investment. Yet, Africa needs properly functioning financial markets for a more efficient allocation of resources for growth and risk diversification. How can African go...

  6. Understanding the Rise of African Business

    DEFF Research Database (Denmark)

    Jorem, Kaja Tvedten; Hansen, Michael Wendelboe; Jeppesen, Søren

    2014-01-01

    enterprises, observing that while much research is focusing on the role of the African business environments for enterprise development, much less attention has been devoted to the role of firm-specific capabilities, strategies and management. The paper concludes by advocating a contingency approach to...... research on African enterprise development that emphasizes the interplay between firm-specific factors and the specificities of the African business environment. Originality/value: The paper provides a comprehensive literature review on African enterprise development and presents a novel framework for......Purpose: In light of recent enthusiasm over African private sector development, the purpose of this paper is to review the business literature on African enterprise development with a view of identifying lacunas in the literature and of developing an analytical framework that may guide future...

  7. Ideology and the possibility of African political theory: African socialism and “ubuntu” compared

    OpenAIRE

    Gil, Manuel

    2011-01-01

    This article explores the lack of investigation into African political theory in the postcolonial period. After discussing the epistemological problems in the study of African political thought, the paper then adopts Michael Freeden’s methodology for the analysis of political ideologies. Through this approach a comparison is made between African Socialism and ubuntu. African Socialism – as developed by Cabral, Nkrumah, Nyerere and Senghor – is defined by its core commitment to freedom from co...

  8. Ectomycorrhizal symbiosis of tropical African trees

    OpenAIRE

    Bâ, Amadou; Duponnois, Robin; Moyersoen, B.; Diédhiou, A.G.

    2012-01-01

    The diversity, ecology and function of ectomycorrhizal (EM) fungi and ectomycorrhizas (ECMs) on tropical African tree species are reviewed here. While ECMs are the most frequent mycorrhizal type in temperate and boreal forests, they concern an economically and ecologically important minority of plants in African tropical forests. In these African tropical forests, ECMs are found mainly on caesalpionioid legumes, Sarcolaenaceae, Dipterocarpaceae, Asterpeiaceae, Phyllantaceae, Sapotaceae, Papil...

  9. 21st Century South African Science Fiction

    OpenAIRE

    CARAIVAN LUIZA

    2014-01-01

    The paper analyses some aspects of South African science fiction, starting with its beginnings in the 1920s and focusing on some 21st century writings. Thus Lauren Beukes’ novels Moxyland (2008) and Zoo City (2010) are taken into consideration in order to present new trends in South African literature and the way science fiction has been marked by Apartheid. The second South African science fiction writer whose writings are examined is Henrietta Rose-Innes (with her novel Nineveh, published i...

  10. African Music: Source of the Blues

    OpenAIRE

    Bayer, Konrad Sidney

    2010-01-01

    [Abstract] African music is the primary source for the blues. Scholars have supplied ample evidence to support this assertion. However, the African retentions still present in the blues are not immediately apparent. African music and the blues share many similarities, including the predominance of rhythm, the uses of music as social commentary and critique, types of instruments, and musical structure. Slaves brought their culture with them to the New World when they were forcibly taken from t...

  11. Representation of African Heritage in Trinidad Carnival

    OpenAIRE

    三吉, 美加

    2016-01-01

    This paper focuses on the cultural representation of African Trinidadian or African creole in Trinidad Carnival. The Republic of Trinidad and Tobago is the most ethnically and culturally diverse society in the East Caribbean. This diversity comprises of 40 percent of East Indians, 40 percent of Africans, and 20 percent of mixed race such as Chinese, Syrians, Lebanese, and Europeans. In the course of making tourism a national agenda, Carnival has gained commercial values, diversifying particip...

  12. 75 FR 45600 - African Development Foundation, Board of Directors Meeting

    Science.gov (United States)

    2010-08-03

    ...; ] AFRICAN DEVELOPMENT FOUNDATION African Development Foundation, Board of Directors Meeting Time: Tuesday, August 17, 2010, 8:30 a.m. to 1 p.m. Place: African Development Foundation, Conference Room, 1400...

  13. 75 FR 2844 - African Development Foundation, Board of Directors Meeting

    Science.gov (United States)

    2010-01-19

    ...; ] AFRICAN DEVELOPMENT FOUNDATION African Development Foundation, Board of Directors Meeting Time: Tuesday, January 26, 2010, 8:30 a.m. to 1 p.m. Place: African Development Foundation, Conference Room, 1400...

  14. 75 FR 14418 - African Development Foundation, Board of Directors Meeting

    Science.gov (United States)

    2010-03-25

    ...; ] AFRICAN DEVELOPMENT FOUNDATION African Development Foundation, Board of Directors Meeting Time: Tuesday, April 13, 2010, 9:30 a.m. to 1 p.m. Place: African Development Foundation, Conference Room, 1400...

  15. The State of African Stock Markets

    OpenAIRE

    Mahama, Adnan

    2013-01-01

    The paper looks at the state of African stock markets during and after the global economic crisis of 2008. The research focuses on the market performance of 15 African stock exchanges from 2007-2012. The size and liquidity of stock markets in the African region is discussed in this thesis. In addition, it compares the performances of a few indexes in the emerging and developed markets to that of African indexes. Data is gathered from individual stock markets as well as notable institutions su...

  16. Race, health, and the African Diaspora.

    Science.gov (United States)

    Spigner, Clarence

    Health inequalities exist throughout the African Diaspora and are viewed in this article as largely color-coded. In developed, developing, and undeveloped nations today, "racial" stratification is consistently reflected in an inability to provide adequate health regardless of national policy or ideology. For instance, African Americans experience less than adequate health care very similar to Blacks in Britain, in spite of each nations differing health systems. Latin America's Africana Negra communities experience poorer health similar to Blacks throughout the Caribbean. The African continent itself is arguably the poorest on earth. A common history of racism correlates with health disparities across the African Diaspora. PMID:18364304

  17. Variability of {sup 10}Be and {delta}{sup 18}O in snow pits from Greenland and a surface traverse from Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Berggren, A.-M. [Dept. of Earth Sciences, Uppsala University, Villav. 16, 752 36 Uppsala (Sweden); Aldahan, A., E-mail: ala.aldahan@geo.uu.se [Dept. of Earth Sciences, Uppsala University, Villav. 16, 752 36 Uppsala (Sweden); Dept. of Geology, United Arab Emirates University, P.O. Box 17551 Al Ain (United Arab Emirates); Possnert, G. [Tandem Laboratory, Uppsala University, P.O. Box 529, 751 20 Uppsala (Sweden); Hansson, M. [Dept. of Physical Geography and Quaternary Geology, Stockholm University, 106 91 Stockholm (Sweden); Steen-Larsen, H.C. [Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej, 30,2100 Copenhagen (Denmark); Sturevik Storm, A. [Dept. of Earth Sciences, Uppsala University, Villav. 16, 752 36 Uppsala (Sweden); Moerth, C.-M. [Dept. of Geology and Geochemistry, Stockholm University, 106 91 Stockholm (Sweden); Murad, A. [Dept. of Geology, United Arab Emirates University, P.O. Box 17551 Al Ain (United Arab Emirates)

    2013-01-15

    To examine temporal variability of {sup 10}Be in glacial ice, we sampled snow to a depth of 160 cm at the NEEM (North Greenland Eemian Ice Drilling) drilling site in Greenland. The samples span three years between the summers of 2006 and 2009. At the same time, spatial variability of {sup 10}Be in glacial ice was explored through collection of the upper {approx}5 cm of surface snow in Antarctica during part of the Swedish-Japanese traverse from Svea to Syowa station during the austral summer in 2007-2008. The results of the Greenlandic {sup 10}Be snow suggested variable concentrations that apparently do not clearly reflect the seasonal change as indicated by the {delta}{sup 18}O data. The {sup 10}Be concentration variability most likely reflects also effects of aerosol loading and deposition pathways, possibly in combination with post-depositional processes. The Antarctic traverse data expose a negative correlation between {sup 10}Be and {delta}{sup 18}O, while there are weaker but still significant correlations to altitude and distance to the coast (approximated by the distance to the 70th latitude). These relationships indicate that geographical factors, mainly the proximity to the coast, may strongly affect {sup 10}Be concentrations in snow in Queen Maud Land, Antarctica.

  18. Case study analysis of the legal and institutional obstacles and incentives to the development of the hydroelectric power of the Boardman River at Traverse City, Michigan

    Energy Technology Data Exchange (ETDEWEB)

    None,

    1980-05-01

    An analytic description of one decision-making process concerning whether or not to develop the hydroelectric potential of the Boardman River is presented. The focus of the analysis is on the factor that the developers considered, or should consider in making a responsible commitment to small-scale hydroelectric development. Development of the Boardman River would occur at the five dam sites. Two existing dams, owned by the county, previously generated hydroelectricity, as did a third before being washed out. One dam has never been utilized. It is owned by the city which also owns the washed-out area. The study concludes that hydroelectric power is feasible at each. Grand Traverse County and Traverse City would engage in a joint venture in developing the resource. Chapter I presents a detailed description of the developers, the river resource, and the contemplated development. Chapter II is an analysis of the factors affecting the decision making process. Chapter III summarizes the impact of the more significant barriers and incentives and presents recommendations that, if implemented, will favorably affect decisions to develop small-scale hydroelectric generation capability.

  19. Integrated enhanced bioremediation and vacuum extraction for remediation of a hydrocarbon release in response to oscillating hydrologic conditions 'Traverse Co-Bio-Vac'

    International Nuclear Information System (INIS)

    The use of enhanced in-situ biological treatment and vacuum extraction has been demonstrated to be successful in the remediation of ground water and soil contaminated with hydrocarbons. Seasonal fluctuations in the ground water causes the zone of contamination to be in the either saturated or unsaturated zone of the aquifer. In order to address these conditions, an integrated engineering design approach is being taken for the full scale remediation of an aviation of an aviation gasoline spill at the US Coast Guard Air Station at Traverse City, Township, Michigan. Enhanced aerobic biodegradation will be utilized during the periods of high water table whereby most of the contaminated interval is saturated. Carbon treated water will be utilized from the existing ground water plume. Oxygen will be injected via an oxygen generator to saturate the process stream prior to discharge to the aquifer. During low water table conditions, the same infrastructure will be utilized as a modified vacuum extraction system. The same injection wells used during the high water table would then be used during the low table condition as vapor extraction wells. The vapors will be routed to an above-ground catalytic incinerator for compound destruction. This integrated approach, entitled 'Traverse Co-Bio-Vac,' should reduce the capital costs of installing a full scale remedial system as well allowing the system to operate efficiently depending on water table conditions. The system is expected to be constructed in 1992

  20. LGBT African-American Individuals and African-American Same-Sex Couples

    OpenAIRE

    Gates, Gary J.; Kastanis, Angel

    2013-01-01

    An estimated 1,018,700 or 3.7 percent of African-American adults consider themselves lesbian, gay, bisexual or transgender (LGBT) and 34 percent of African-American same-sex couples are raising children. Currently, the estimated 84,000 African-American individuals in same-sex couples tend to live in areas where there are higher proportions of African-Americans. For example, a quarter of African-American same-sex couples live in Georgia, New York, North Carolina, and Maryland. The rep...

  1. The African agent discovered: The recognition and involvement of the African biblical interpreter in Bible translation

    Directory of Open Access Journals (Sweden)

    S V Coertze

    2008-05-01

    Full Text Available This article explores the extent to which the role of the African biblical interpreter is acknowledged in the process of Bible translation, as the Bible and Bible translation form an important part of the establishment of the African church on the continent of Africa. It points out that even though foreign discovery of African agency in Bible translation is evident, indigenous discovery of the same is largely absent. Part of the relevance of this article is for the African church to own and be actively involved in the translation of the Bible into the remaining African languages that are in need of a translation of the Bible.

  2. Trypanosoma livingstonei: a new species from African bats supports the bat seeding hypothesis for the Trypanosoma cruzi clade

    OpenAIRE

    Lima, Luciana; Espinosa-Álvarez, Oneida; Hamilton, Patrick B; Neves, Luis; Takata, Carmen SA; Campaner, Marta; Attias, Márcia; De Souza, Wanderley; Camargo, Erney P.; Teixeira, Marta MG

    2013-01-01

    Background Bat trypanosomes have been implicated in the evolutionary history of the T. cruzi clade, which comprises species from a wide geographic and host range in South America, Africa and Europe, including bat-restricted species and the generalist agents of human American trypanosomosis T. cruzi and T. rangeli. Methods Trypanosomes from bats (Rhinolophus landeri and Hipposideros caffer) captured in Mozambique, southeast Africa, were isolated by hemoculture. Barcoding was carried out throug...

  3. Population genetics of African ungulates

    DEFF Research Database (Denmark)

    Lorenzen, Eline

    Molecular genetic techniques were used to gain insights into the evolutionary forces that have shaped the present day diversity of African savannah ungu-lates, which constitute the most species-rich mega faunal assemblage on earth. The studies included in this thesis represent individual species......-specific data sets, which are used to elucidate evolutionary processes of importance to the savannah ungulate community. Patterns of DNA variation were analyzed to assess the genetic signatures of Pleistocene refugia and investigate aspects of speciation, intraspecific structuring, hybridization, and historic...

  4. Depression, Sociocultural Factors, and African American Women

    Science.gov (United States)

    Hunn, Vanessa Lynn; Craig, Carlton David

    2009-01-01

    The authors discuss depression in African American women from a sociocultural perspective, including aspects of oppression and racism that affect symptom manifestation. The authors highlight John Henryism as a coping mechanism, the history and continuing role of the African American church as a safe haven, and strategies for culturally competent…

  5. Cancer and the African American Experience

    Science.gov (United States)

    The first plenary of the EPEC-O (Education in Palliative and End-of-Life Care for Oncology) Self-Study: Cultural Considerations When Caring for African Americans explores the many factors that lead to inequalities in cancer care outcomes for African Americans.

  6. African Americans in the Early Republic.

    Science.gov (United States)

    Nash, Gary B.

    2000-01-01

    Discusses five topics on African Americans that are essential to studying United States History in the years between 1760 and 1830: (1) African Americans in the Revolutionary War ; (2) the rise of free black communities; (3) early abolitionism; (4) the spread of slavery; and (5) black resistance to slavery. (CMK)

  7. African-American Student Achievement Research Project.

    Science.gov (United States)

    Wagstaff, Mark; Melton, Jerry; Lawless, Brenda; Combs, Linda

    Data from the Texas Assessment of Academic Skills (TAAS) reveal that gains in performance for the African American student population of Region VII of the state's educational system were not keeping pace with the performance of African Americans in the rest of Texas. This study investigated practices in school districts in the region in which…

  8. New data on African health professionals abroad

    Directory of Open Access Journals (Sweden)

    Clemens Michael A

    2008-01-01

    Full Text Available Abstract Background The migration of doctors and nurses from Africa to developed countries has raised fears of an African medical brain drain. But empirical research on the causes and effects of the phenomenon has been hampered by a lack of systematic data on the extent of African health workers' international movements. Methods We use destination-country census data to estimate the number of African-born doctors and professional nurses working abroad in a developed country circa 2000, and compare this to the stocks of these workers in each country of origin. Results Approximately 65,000 African-born physicians and 70,000 African-born professional nurses were working overseas in a developed country in the year 2000. This represents about one fifth of African-born physicians in the world, and about one tenth of African-born professional nurses. The fraction of health professionals abroad varies enormously across African countries, from 1% to over 70% according to the occupation and country. Conclusion These numbers are the first standardized, systematic, occupation-specific measure of skilled professionals working in developed countries and born in a large number of developing countries.

  9. British African Caribbean Women and Depression

    Science.gov (United States)

    Adkison-Bradley, Carla; Maynard, Donna; Johnson, Phillip; Carter, Stephaney

    2009-01-01

    Depression is a common condition among women in the United Kingdom. However, little is known about the context of depression among British African Caribbean women. This article offers a preliminary discussion regarding issues and information pertaining to depression among British African Caribbean women. Characteristics and symptoms of depression…

  10. An African VLBI network of radio telescopes

    CERN Document Server

    Gaylard, M J; Combrinck, L; Booth, R S; Buchner, S J; Fanaroff, B L; MacLeod, G C; Nicolson, G D; Quick, J F H; Stronkhorst, P; Venkatasubramani, T L

    2014-01-01

    The advent of international wideband communication by optical fibre has produced a revolution in communications and the use of the internet. Many African countries are now connected to undersea fibre linking them to other African countries and to other continents. Previously international communication was by microwave links through geostationary satellites. These are becoming redundant in some countries as optical fibre takes over, as this provides 1000 times the bandwidth of the satellite links. In the 1970's and 1980's some two dozen large (30 m diameter class) antennas were built in various African countries to provide the satellite links. Twenty six are currently known in 19 countries. As these antennas become redundant, the possibility exists to convert them for radio astronomy at a cost of roughly one tenth that of a new antenna of similar size. HartRAO, SKA Africa and the South African Department of Science and Technology (DST) have started exploring this possibility with some of the African countries...

  11. Android应用程序GUI遍历的自动化方法%Automatic Method for GUI Traversal in Android Applications

    Institute of Scientific and Technical Information of China (English)

    赵耀宗; 程绍银; 蒋凡

    2015-01-01

    GUI-based analysis and testing methods of Android applications have become a research focus in recent years. Automation and high GUI coverage could improve the efficiency and effectiveness of most methods. However, previous work is insufficient to meet the requirements of automation and high GUI coverage. In this paper, we propose an automatic method of traverseing the GUIs in Android applications whose source codes are not available. The main idea of the method is to simulate user actions to explore the GUIs of an app automatically. The work tackles some key issues mainly in three aspects: extraction and process of UI elements, simulation of user actions, algorithm design and model building of GUI traversal. The result of experiments shows that the method is effective to traverse the GUIs of an application with a high GUI coverage. Furthermore, this method could assist other researches, such as program security analysis, GUI testing.%近来针对 Android 应用程序的基于 GUI(图形用户界面)的分析和测试方法已经成为一个研究热点.自动化技术和较高的 GUI 覆盖率可以提高大部分方法的效率和效果.然而以前的工作并不能充分满足自动化和高GUI覆盖率的要求.提出了一种在不需要程序源代码的情况下遍历Android应用程序GUI的自动化方法.其主要思想是通过模拟用户的行为自动探测Android应用程序的GUI.我们的工作主要解决了UI元素提取和处理、用户行为模拟、GUI遍历算法设计和模型构建三方面中的一些关键问题.实验结果表明,该方法能获得较高的GUI覆盖率可以有效遍历应用程序的GUI.此外,该方法也将有助于程序安全分析、GUI测试等其他研究.

  12. South African AIDS plan criticised.

    Science.gov (United States)

    Sidley, P

    1998-10-17

    In a television broadcast, Deputy President Mbeki of South Africa announced a campaign against HIV/AIDS that would involve coordination between various government departments and nongovernmental organizations. Mbeki, who is associated with Virodene (a drug treatment for AIDS that is considered a scam), replaced President Mandela at the last minute in the broadcast. Two days after the broadcast, the government refused to support treatment of pregnant women infected with HIV with zidovudine to prevent transmission of the virus to the baby. The treatment is considered cost-effective by AIDS workers and public health officials. According to Mark Heywood of the AIDS law project at Witwatersrand University, 16% of pregnant women attending antenatal clinics were HIV-positive in 1997; this means that about 3 million South Africans (8% of the population) were living with HIV. Heywood said that the government believes there are 1500 new cases daily. By the end of 1998, 3.5 million South Africans will be living with HIV. Although the government is asking other sectors to join in the campaign, what the government is doing is unclear. Mother-to-child transmission of HIV is second only to transmission of the virus through heterosexual sex in South Africa. PMID:9841037

  13. Public health assessment for Grand Traverse Overall Supply Company, Greilickville, Leelanau County, Michigan, Region 5. Cerclis No. MID017418559. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1994-01-21

    The United States Environmental Protection Agency (U.S. EPA) placed the Grand Traverse Overall Supply site on the National Priorities List (NPL) on September 8, 1983. From 1953 through 1977, GTOS disposed of waste water from the process in a dry well and four lagoons on their property. Since 1977, they have used the township sewer system. In 1978, tetrachloroethylene (also known as perchloroethylene or PCE) and trichloroethylene (TCE) were found in the water in wells serving a school adjacent to GTOS and several nearby residences. The soil around the dry well was excavated and taken off-site for disposal. The lagoons were filled in, and covered with gravel or grass. The site currently poses no apparent public health hazard. Trace amounts of PCE in well water have been detected in the most recent testing, however, the amounts are below the level of public health concern.

  14. Modeling of growth and evaporation effects on the extinction of 1.0-micron solar radiation traversing stratospheric sulfuric acid aerosols

    Science.gov (United States)

    Yue, G. K.; Deepak, A.

    1981-01-01

    The effects of growth and evaporation of stratospheric sulfuric acid aerosols on the extinction of solar radiation traversing such an aerosol medium are reported for the case of 1.0-micron solar radiation. Modeling results show that aerosol extinction is not very sensitive to the change of ambient water vapor concentration, but is sensitive to ambient temperature changes, especially at low ambient temperatures and high ambient water vapor concentration. A clarification is given of the effects of initial aerosol size distribution and composition on the change of aerosol extinction due to growth and evaporation processes. It is shown that experiments designed to observe solar radiation extinction of aerosols may also be applied to the determination of observed changes in aerosol optical properties, environmental parameters, or the physical and optical characteristics of sulfate aerosols.

  15. Educational Adaptation and Pan-Africanism: Trends in Africa.

    Science.gov (United States)

    Marah, John Karefah

    1987-01-01

    European colonialists believed that Africans should be educated in African traditional values, and that Africans should be made into dedicated workers, not holders of power. The African nationalists of the 1960s, in contrast, rejected most of the arduous aspects of European education as instruments of domination, and lay the foundation for the…

  16. 76 FR 6519 - National African American History Month, 2011

    Science.gov (United States)

    2011-02-04

    ... imagined, African Americans have strengthened our Nation by leading reforms, overcoming obstacles, and... of African Americans to our Nation's history and identity. This year's theme, ``African Americans and... enslaved within rebellious areas, he also opened the door for African Americans to join the Union...

  17. African widows: anthropological and historical perspectives.

    Science.gov (United States)

    Cattell, Maria G

    2003-01-01

    Variety characterizes widows' experiences around the world and in Africa south of the Sahara. This article explores the socioeconomic and cultural contexts of African widowhood, using anthropological studies in a number of African societies, including the author's research among Abaluyia of western Kenya. Some features of African widowhood are characteristic of African women's lives regardless of their marital status: their embeddedness in kinship systems and dependence on those systems for claims to productive resources, their economic self-reliance (which does not mean prosperity), strongly gendered divisions of labor, and the pervasiveness of patriarchal gender relations. Other features are specific to widowhood, including remarriage, issues of personal autonomy, and loss of status, access to productive resources and social support. Colonial and postcolonial historical transformations, including Africa's current dire economic situation and the AIDS epidemic, are considered in relation to widows' lives. An interesting question (given the theme of this edited volume) is whether a husband' s death puts African widows "on their own again," and whether, given African systems of kinship and marriage, most African women (and indeed men, too) can ever be said to be "on their own." PMID:14604001

  18. The Economics of the African Media

    OpenAIRE

    Cage, Julia

    2014-01-01

    The focus of this chapter is on the economics of sub-Saharan African media. Using the history of sub-Saharan African newspapers as well as historical evidence from Europe and the United States, I study the emergence of market-oriented journalism and of an independent and informative press in sub-Saharan Africa. I document the extent to which sub-Saharan African newspapers have followed the same development steps than newspapers in other countries, moving from living off patronage and governme...

  19. MISCONCEPTIONS OF DEPRESSION IN AFRICAN AMERICANS

    Directory of Open Access Journals (Sweden)

    Zohaib eSohail

    2014-06-01

    Full Text Available Major depression is a very common disabling disorder. Although the relationship between race and depression is complex, depression affects all races, all ethnic and geographic locations as well as all age groups. The prevalence of depression in African Americans is controversial, due to the paucity of research. The deficit in the knowledge and skills in treating depression in African Americans have not been adequately addressed so far. Inadequate and insufficient data on African Americans contributes to the problems of under diagnoses, misdiagnosis and under treatment of depression. This article will highlight the existing problem of depression in Afro American with a focus on diagnostic and treatment issues.

  20. The African concept of caring for life

    Directory of Open Access Journals (Sweden)

    Maake Masango

    2005-10-01

    Full Text Available This article analyses the village concept of caring among African people. The old pattern of caring was based on the concept of ubuntu (humanity which respects people, because they are created in the imago Dei. Then the article compares the western concept of caring, which is based on individualism and people's privacy. Finally, economy, globalisation and this western concept are analysed. The impact of the above concepts affects Africans in urban areas, who are caught up in the two worlds, namely the African and western worlds.

  1. Mandela’s Favourite African Folktales

    OpenAIRE

    Carmen Concilio

    2014-01-01

    In this essay I would like to examine the selection of African tales that Nelson Mandela took care to leave as heritage to the future generations, not only to children, and not only to African children. The fact that a political leader, ex freedom fighter and political prisoner dedicated his time to the collection and editing of stories from all over the African continent to be addressed to new readers as simple entertainment or as educational tools clearly testifies to the great humanity, cu...

  2. AFRA. African Regional Co-operative Agreement

    International Nuclear Information System (INIS)

    This publication provides an outline of the African Regional Co-operation Agreement for research, development and training related to nuclear science and technology (AFRA). The agreement stems from an initiative of several African member states of the IAEA to get the agency to help establish an African regional arrangement which would be similar to arrangements which were already in place in the Asian and Latin American regions. Through this regional approach to development, AFRA seeks to accelerate moves toward self-sufficiency in scientific disciplines and appropriate technologies by coordinating intellectual and physical resources and disseminating innovative methods and practices in a cost-effective manner

  3. 21st Century South African Science Fiction

    Directory of Open Access Journals (Sweden)

    CARAIVAN LUIZA

    2014-12-01

    Full Text Available The paper analyses some aspects of South African science fiction, starting with its beginnings in the 1920s and focusing on some 21st century writings. Thus Lauren Beukes’ novels Moxyland (2008 and Zoo City (2010 are taken into consideration in order to present new trends in South African literature and the way science fiction has been marked by Apartheid. The second South African science fiction writer whose writings are examined is Henrietta Rose-Innes (with her novel Nineveh, published in 2011 as this consolidates women's presence in the SF world.

  4. The African American Wellness Village in Portland, Ore

    OpenAIRE

    McKeever, Corliss; Koroloff, Nancy; Faddis, Collaine

    2006-01-01

    More than 80% of African Americans in Oregon reside in the Portland metropolitan area; African Americans comprise 1.7% of the state's population. Although relatively small, the African American population in the state experiences substantial health disparities. The African American Health Coalition, Inc was developed to implement initiatives that would reduce these disparities and to promote increased communication and trust between the African American community and local institutions and or...

  5. Palaearctic-African Bird Migration

    DEFF Research Database (Denmark)

    Iwajomo, Soladoye Babatola

    -Saharan migrants than autumn migration. Information about the behavior and interactions of migrants during the nonbreeding season in sub-Saharan Africa is also scarce for many species. Furthermore, very little is known about intra-African migration. This thesis summarizes my research on the autumn migration of...... still unknown. The fourth paper and one manuscript investigate the behavior of garden warblers Sylvia borin, during the non-breeding season in Nigeria. The first paper shows that the species also utilizes habitats south of the savannah region, presumably on its way to the final goal area. Individuals...... also molt their flight feathers at this location and intraspecific interactions are non-aggressive. The second manuscript investigates whether variations in the timing of migration of wader species at a stopover site in southeast Sweden is influence by local or regional climatic variables. The...

  6. African diatom palaeoecology and biostratigraphy

    Science.gov (United States)

    Gasse, F.; Fourtanier, E.

    This paper illustrates the different types of information which can be deduced from African diatoms studies. The first section is devoted to the reconstruction of palaeoenvironments. The accuracy of ecological data (estimates of ecological variables e.g. types of habitats, water chemistry…) depends on the times scale and on the spatial scale considered: short-term environments in a given waterbody, environmental evolution during individual humid episodes considered locally or regionally, long-term changes in diatom flora induced by major climatic tendencies at a regional or continental scale. One then summarizes our present state of knowledge in diatom biostratigraphy in Africa. Several centric taxa, belonging to the genera Aulacoseira, Mesodictyon, Cyclotella, Stephanodiscus and Cyclostephanos appear to have limited stratigraphical ranges and to be good chronological markers.

  7. Africa Pentecostalized? Understanding the African appropriation of Pentecostalism in light of African perspectives

    OpenAIRE

    Østhassel, Ole Aleksander

    2013-01-01

    I want to prepare an understanding of why Pentecostalism seems to be so attractive in Africa. I will outline Ogbu Kalu's understanding of a resonance between African traditional culture and Pentecostalism, and then add perspectives from other African scholars. And the research problem follows: How can we understand the appropriation of Pentecostalism in Africa in light of Ogbu Kalu? Research questions will be: In what way do Pentecostalism and African traditional cult...

  8. Enhancing the African bioethics initiative

    Directory of Open Access Journals (Sweden)

    Ogundiran Temidayo O

    2004-10-01

    Full Text Available Abstract Background Medical ethics has existed since the time of Hippocrates. However, formal training in bioethics did not become established until a few decades ago. Bioethics has gained a strong foothold in health sciences in the developed world, especially in Europe and North America. The situation is quite different in many developing countries. In most African countries, bioethics – as established and practiced today in the west- is either non-existent or is rudimentary. Discussion Though bioethics has come of age in the developed and some developing countries, it is still largely "foreign" to most African countries. In some parts of Africa, some bioethics conferences have been held in the past decade to create research ethics awareness and ensure conformity to international guidelines for research with human participants. This idea has arisen in recognition of the genuine need to develop capacity for reviewing the ethics of research in Africa. It is also a condition required by external sponsors of collaborative research in Africa. The awareness and interest that these conferences have aroused need to be further strengthened and extended beyond research ethics to clinical practice. By and large, bioethics education in schools that train doctors and other health care providers is the hook that anchors both research ethics and clinical ethics. Summary This communication reviews the current situation of bioethics in Africa as it applies to research ethics workshops and proposes that in spite of the present efforts to integrate ethics into biomedical research in Africa, much still needs to be done to accomplish this. A more comprehensive approach to bioethics with an all-inclusive benefit is to incorporate formal ethics education into health training institutions in Africa.

  9. Extraordinary life history in African annual fishes

    Czech Academy of Sciences Publication Activity Database

    Blažek, Radim; Polačik, Matej; Reichard, Martin

    Bujumbura: University of Burundi, 2013. s. 52-53. [International Conference of the Pan African Fish and Fisheries Association (PAFFA) /5./. 16.09.2013-20.09.2013, Bujumbura] Institutional support: RVO:68081766 Keywords : Nothobranchius * Mozambique Subject RIV: EG - Zoology

  10. African Studies Abstracts Online: number 28, 2009

    OpenAIRE

    African Studies Centre

    2009-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 28 (2009). African Studies Centre, Leiden.

  11. African Studies Abstracts Online: number 25, 2009

    OpenAIRE

    African Studies Centre

    2009-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 25 (2009). African Studies Centre, Leiden.

  12. African Studies Abstracts Online: number 10, 2005

    OpenAIRE

    African Studies Centre

    2005-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 10 (2005). African Studies Centre, Leiden.

  13. African Studies Abstracts Online: number 36, 2011

    OpenAIRE

    African Studies Centre

    2011-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 36 (2011). African Studies Centre, Leiden.

  14. African Studies Abstracts Online: number 23, 2008

    OpenAIRE

    African Studies Centre

    2008-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 23 (2008). African Studies Centre, Leiden.

  15. African Studies Abstracts Online: number 30, 2010

    OpenAIRE

    African Studies Centre

    2010-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 30 (2010). African Studies Centre, Leiden.

  16. African Studies Abstracts Online: number 20, 2007

    OpenAIRE

    African Studies Centre

    2007-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 20 (2007). African Studies Centre, Leiden.

  17. African Studies Abstracts Online: number 50, 2015

    OpenAIRE

    African Studies Centre

    2015-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 50 (2015). African Studies Centre, Leiden.

  18. African Studies Abstracts Online: number 34, 2011

    OpenAIRE

    African Studies Centre

    2011-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 34 (2011). African Studies Centre, Leiden.

  19. African Studies Abstracts Online: number 11, 2005

    OpenAIRE

    African Studies Centre

    2005-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 11 (2005). African Studies Centre, Leiden.

  20. African Studies Abstracts Online: number 52, 2015

    OpenAIRE

    African Studies Centre

    2015-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 52 (2015). African Studies Centre, Leiden.

  1. African Studies Abstracts Online: number 15, 2006

    OpenAIRE

    African Studies Centre

    2006-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 15 (2006). African Studies Centre, Leiden.

  2. African Studies Abstracts Online: number 48, 2014

    OpenAIRE

    African Studies Centre

    2014-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 48 (2014). African Studies Centre, Leiden.

  3. African Studies Abstracts Online: number 22, 2008

    OpenAIRE

    African Studies Centre

    2008-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 22 (2008). African Studies Centre, Leiden.

  4. African Studies Abstracts Online: number 43, 2013

    OpenAIRE

    African Studies Centre

    2013-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 43 (2013). African Studies Centre, Leiden.

  5. African Studies Abstracts Online: number 17, 2007

    OpenAIRE

    African Studies Centre

    2007-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 17 (2007). African Studies Centre, Leiden.

  6. African Studies Abstracts Online: number 18, 2007

    OpenAIRE

    African Studies Centre

    2007-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 18 (2007). African Studies Centre, Leiden.

  7. African Studies Abstracts Online: number 38, 2012

    OpenAIRE

    African Studies Centre

    2012-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 38 (2012). African Studies Centre, Leiden.

  8. African Studies Abstracts Online: number 9, 2005

    OpenAIRE

    African Studies Centre

    2005-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 9 (2005). African Studies Centre, Leiden.

  9. African Studies Abstracts Online: number 31, 2010

    OpenAIRE

    African Studies Centre

    2010-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 31 (2010). African Studies Centre, Leiden.

  10. African Studies Abstracts Online: number 40, 2012

    OpenAIRE

    African Studies Centre

    2012-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 40 (2012). African Studies Centre, Leiden.

  11. African Studies Abstracts Online: number 27, 2009

    OpenAIRE

    African Studies Centre

    2009-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 27 (2009). African Studies Centre, Leiden.

  12. African Studies Abstracts Online: number 37, 2012

    OpenAIRE

    African Studies Centre

    2012-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 37 (2012). African Studies Centre, Leiden.

  13. African Studies Abstracts Online: number 26, 2009

    OpenAIRE

    African Studies Centre

    2009-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 26 (2009). African Studies Centre, Leiden.

  14. African Studies Abstracts Online: number 29, 2010

    OpenAIRE

    African Studies Centre

    2010-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 29 (2010). African Studies Centre, Leiden.

  15. African Studies Abstracts Online: number 33, 2011

    OpenAIRE

    African Studies Centre

    2011-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 33 (2011). African Studies Centre, Leiden.

  16. African Studies Abstracts Online: number 42, 2013

    OpenAIRE

    African Studies Centre

    2013-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 42 (2013). African Studies Centre, Leiden.

  17. African Studies Abstracts Online: number 45, 2014

    OpenAIRE

    African Studies Centre

    2014-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 45 (2014). African Studies Centre, Leiden.

  18. African Studies Abstracts Online: number 19, 2007

    OpenAIRE

    African Studies Centre

    2007-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 19 (2007). African Studies Centre, Leiden.

  19. African Studies Abstracts Online: number 46, 2014

    OpenAIRE

    African Studies Centre

    2014-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 46 (2014). African Studies Centre, Leiden.

  20. African Studies Abstracts Online: number 32, 2010

    OpenAIRE

    African Studies Centre

    2010-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 32 (2010). African Studies Centre, Leiden.