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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. Mammalian African trypanosome VSG coat enhances tsetse's vector competence.

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    Aksoy, Emre; Vigneron, Aurélien; Bing, XiaoLi; Zhao, Xin; O'Neill, Michelle; Wu, Yi-Neng; Bangs, James D; Weiss, Brian L; Aksoy, Serap

    2016-06-21

    Tsetse flies are biological vectors of African trypanosomes, the protozoan parasites responsible for causing human and animal trypanosomiases across sub-Saharan Africa. Currently, no vaccines are available for disease prevention due to antigenic variation of the Variant Surface Glycoproteins (VSG) that coat parasites while they reside within mammalian hosts. As a result, interference with parasite development in the tsetse vector is being explored to reduce disease transmission. A major bottleneck to infection occurs as parasites attempt to colonize tsetse's midgut. One critical factor influencing this bottleneck is the fly's peritrophic matrix (PM), a semipermeable, chitinous barrier that lines the midgut. The mechanisms that enable trypanosomes to cross this barrier are currently unknown. Here, we determined that as parasites enter the tsetse's gut, VSG molecules released from trypanosomes are internalized by cells of the cardia-the tissue responsible for producing the PM. VSG internalization results in decreased expression of a tsetse microRNA (mir-275) and interferes with the Wnt-signaling pathway and the Iroquois/IRX transcription factor family. This interference reduces the function of the PM barrier and promotes parasite colonization of the gut early in the infection process. Manipulation of the insect midgut homeostasis by the mammalian parasite coat proteins is a novel function and indicates that VSG serves a dual role in trypanosome biology-that of facilitating transmission through its mammalian host and insect vector. We detail critical steps in the course of trypanosome infection establishment that can serve as novel targets to reduce the tsetse's vector competence and disease transmission. PMID:27185908

  6. Early invasion of brain parenchyma by African trypanosomes.

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    Ute Frevert

    Full Text Available Human African trypanosomiasis or sleeping sickness is a vector-borne parasitic disease that has a major impact on human health and welfare in sub-Saharan countries. Based mostly on data from animal models, it is currently thought that trypanosome entry into the brain occurs by initial infection of the choroid plexus and the circumventricular organs followed days to weeks later by entry into the brain parenchyma. However, Trypanosoma brucei bloodstream forms rapidly cross human brain microvascular endothelial cells in vitro and appear to be able to enter the murine brain without inflicting cerebral injury. Using a murine model and intravital brain imaging, we show that bloodstream forms of T. b. brucei and T. b. rhodesiense enter the brain parenchyma within hours, before a significant level of microvascular inflammation is detectable. Extravascular bloodstream forms were viable as indicated by motility and cell division, and remained detectable for at least 3 days post infection suggesting the potential for parasite survival in the brain parenchyma. Vascular inflammation, as reflected by leukocyte recruitment and emigration from cortical microvessels, became apparent only with increasing parasitemia at later stages of the infection, but was not associated with neurological signs. Extravascular trypanosomes were predominantly associated with postcapillary venules suggesting that early brain infection occurs by parasite passage across the neuroimmunological blood brain barrier. Thus, trypanosomes can invade the murine brain parenchyma during the early stages of the disease before meningoencephalitis is fully established. Whether individual trypanosomes can act alone or require the interaction from a quorum of parasites remains to be shown. The significance of these findings for disease development is now testable.

  7. 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.

  8. The interaction between nutrition and metabolism in West African Dwarf goats, infected with trypanosomes.

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    Dam, van J.T.P.

    1996-01-01

    In a series of experiments the interaction between nutrition and energy- and nitrogen metabolism of West African Dwarf goats, infected with trypanosomes was studied. Animals were injected with trypanosomes, and feed intake, energy and nitrogen balance and blood metabolites and hormones were measured

  9. 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

  10. 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.

  11. The genetics of African trypanosomes : vector-borne diseases : trypanosomosis

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    A. Tait

    2009-09-01

    Full Text Available The occurrence of genetic exchange is not only a fundamental property of an organism but its occurrence provides us with methods of analysis that can be used to dissect the basis of important traits. This paper will review the current evidence for a sexual cycle in Trypanosoma brucei and illustrate how genetic analysis can be used as a tool to identify genes of relevance to the disease, its treatment and transmission. The role of this process in the generation of diversity in the field will be illustrated by considering populations of the three sub-species of T. brucei and how the availability of genome sequence data has been exploited to study whether genetic exchange occurs in the trypanosomes infecting livestock. Finally, the use of population genetics as a methodology to identify genes under selection will be discussed and this will be illustrated as an approach to validating markers for drug resistance with examples from other parasitic protozoa.

  12. Phylogeny and Morphological Variability of Trypanosomes from African Pelomedusid Turtles with Redescription of Trypanosoma mocambicum Pienaar, 1962.

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    Dvořáková, Nela; Čepička, Ivan; Qablan, Moneeb A; Gibson, Wendy; Blažek, Radim; Široký, Pavel

    2015-12-01

    Little is known about host specificity, genetic diversity and phylogenetic relationships of African turtle trypanosomes. Using PCR targeting the SSU rRNA gene, we detected trypanosomes in 24 of 134 (17.9%) wild caught African pelomedusid turtles: Pelusios upembae (n=14), P. bechuanicus (n=1), P. rhodesianus (n=3) and P. subniger (n=6). Mixed infection of Trypanosoma species was confirmed by PCR in three specimens of P. upembae, and in one specimen each of P. bechuanicus, P. rhodesianus, and P. subniger. Microscopic examination of stained blood smears revealed two distinct forms (broad and slender) of trypomastigotes. The broad form coincided in morphology with T. mocambicumPienaar, 1962. Accordingly, we have designated this form as the neotype of T. mocambicum. In phylogenetic analysis of the SSU rRNA gene, all the new turtle trypanosome sequences grouped in a single clade within the strongly supported "aquatic" clade of Trypanosoma species. The turtle trypanosome clade was further subdivided into two subclades, which did not correlate with host turtle species or trypanosome morphology. This study provides the first sequence data of Trypanosoma species isolated from freshwater turtles from tropical Africa and extends knowledge on diversity of trypanosomes in the Afrotropical zoogeographical realm.

  13. 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

  14. 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.

  15. Assembling the components of the quorum sensing pathway in African trypanosomes.

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    Mony, Binny M; Matthews, Keith R

    2015-04-01

    African trypanosomes, parasites that cause human sleeping sickness, undergo a density-dependent differentiation in the bloodstream of their mammalian hosts. This process is driven by a released parasite-derived factor that causes parasites to accumulate in G1 and become quiescent. This is accompanied by morphological transformation to 'stumpy' forms that are adapted to survival and further development when taken up in the blood meal of tsetse flies, the vector for trypanosomiasis. Although the soluble signal driving differentiation to stumpy forms is unidentified, a recent genome-wide RNAi screen identified many of the intracellular signalling and effector molecules required for the response to this signal. These resemble components of nutritional starvation and quiescence pathways in other eukaryotes, suggesting that parasite development shares similarities with the adaptive quiescence of organisms such as yeasts and Dictyostelium in response to nutritional starvation and stress. Here, the trypanosome signalling pathway is discussed in the context of these conserved pathways and the possible contributions of opposing 'slender retainer' and 'stumpy inducer' arms described. As evolutionarily highly divergent eukaryotes, the organisation and conservation of this developmental pathway can provide insight into the developmental cycle of other protozoan parasites, as well as the adaptive and programmed developmental responses of all eukaryotic cells.

  16. 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

  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. KHARON Is an Essential Cytoskeletal Protein Involved in the Trafficking of Flagellar Membrane Proteins and Cell Division in African Trypanosomes.

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    Sanchez, Marco A; Tran, Khoa D; Valli, Jessica; Hobbs, Sam; Johnson, Errin; Gluenz, Eva; Landfear, Scott M

    2016-09-16

    African trypanosomes and related kinetoplastid parasites selectively traffic specific membrane proteins to the flagellar membrane, but the mechanisms for this trafficking are poorly understood. We show here that KHARON, a protein originally identified in Leishmania parasites, interacts with a putative trypanosome calcium channel and is required for its targeting to the flagellar membrane. KHARON is located at the base of the flagellar axoneme, where it likely mediates targeting of flagellar membrane proteins, but is also on the subpellicular microtubules and the mitotic spindle. Hence, KHARON is probably a multifunctional protein that associates with several components of the trypanosome cytoskeleton. RNA interference-mediated knockdown of KHARON mRNA results in failure of the calcium channel to enter the flagellar membrane, detachment of the flagellum from the cell body, and disruption of mitotic spindles. Furthermore, knockdown of KHARON mRNA induces a lethal failure of cytokinesis in both bloodstream (mammalian host) and procyclic (insect vector) life cycle stages, and KHARON is thus critical for parasite viability. PMID:27489106

  20. 25 years of African trypanosome research: From description to molecular dissection and new drug discovery ☆ ☆☆

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    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.

  1. The silicon trypanosome

    NARCIS (Netherlands)

    Bakker, Barbara M.; Krauth-Siegel, R. Luise; Clayton, Christine; Matthews, Keith; Girolami, Mark; Westerhoff, Hans V.; Michels, Paul A. M.; Breitling, Rainer; Barrett, Michael P.

    2010-01-01

    African trypanosomes have emerged as promising unicellular model organisms for the next generation of systems biology. They offer unique advantages, due to their relative simplicity, the availability of all standard genomics techniques and a long history of quantitative research. Reproducible cultiv

  2. 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...

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

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    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

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

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    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

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

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    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

  6. 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.

  7. 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...

  8. 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

  9. 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.

  10. 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

  11. 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

  12. 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

  13. 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.

  14. 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)

  15. 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

  16. Species-Specific Adaptations of Trypanosome Morphology and Motility to the Mammalian Host.

    Directory of Open Access Journals (Sweden)

    Joel L Bargul

    2016-02-01

    Full Text Available African trypanosomes thrive in the bloodstream and tissue spaces of a wide range of mammalian hosts. Infections of cattle cause an enormous socio-economic burden in sub-Saharan Africa. A hallmark of the trypanosome lifestyle is the flagellate's incessant motion. This work details the cell motility behavior of the four livestock-parasites Trypanosoma vivax, T. brucei, T. evansi and T. congolense. The trypanosomes feature distinct swimming patterns, speeds and flagellar wave frequencies, although the basic mechanism of flagellar propulsion is conserved, as is shown by extended single flagellar beat analyses. Three-dimensional analyses of the trypanosomes expose a high degree of dynamic pleomorphism, typified by the 'cellular waveform'. This is a product of the flagellar oscillation, the chirality of the flagellum attachment and the stiffness of the trypanosome cell body. The waveforms are characteristic for each trypanosome species and are influenced by changes of the microenvironment, such as differences in viscosity and the presence of confining obstacles. The distinct cellular waveforms may be reflective of the actual anatomical niches the parasites populate within their mammalian host. T. vivax displays waveforms optimally aligned to the topology of the bloodstream, while the two subspecies T. brucei and T. evansi feature distinct cellular waveforms, both additionally adapted to motion in more confined environments such as tissue spaces. T. congolense reveals a small and stiff waveform, which makes these parasites weak swimmers and destined for cell adherence in low flow areas of the circulation. Thus, our experiments show that the differential dissemination and annidation of trypanosomes in their mammalian hosts may depend on the distinct swimming capabilities of the parasites.

  17. 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

  18. Typed combinators for generic traversal

    OpenAIRE

    Lämmel, Ralf; Vonk, J

    2001-01-01

    Lacking support for generic traversal, functional programming languages suffer from a scalability problem when applied to large-scale program transformation problems. As a solution, we introduce emph{functional strategies: typeful generic functions that not only can be applied to terms of any type, but which also allow generic traversal into subterms. We show how strategies are modelled inside a functional language, and we present a combinator library including generic traversal combinators. ...

  19. 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...

  20. 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...

  1. 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.

  2. Trypanosome Motion Represents an Adaptation to the Crowded Environment of the Vertebrate Bloodstream

    Science.gov (United States)

    Heddergott, Niko; Krüger, Timothy; Babu, Sujin B.; Wei, Ai; Stellamanns, Erik; Uppaluri, Sravanti; Pfohl, Thomas; Stark, Holger; Engstler, Markus

    2012-01-01

    Blood is a remarkable habitat: it is highly viscous, contains a dense packaging of cells and perpetually flows at velocities varying over three orders of magnitude. Only few pathogens endure the harsh physical conditions within the vertebrate bloodstream and prosper despite being constantly attacked by host antibodies. African trypanosomes are strictly extracellular blood parasites, which evade the immune response through a system of antigenic variation and incessant motility. How the flagellates actually swim in blood remains to be elucidated. Here, we show that the mode and dynamics of trypanosome locomotion are a trait of life within a crowded environment. Using high-speed fluorescence microscopy and ordered micro-pillar arrays we show that the parasites mode of motility is adapted to the density of cells in blood. Trypanosomes are pulled forward by the planar beat of the single flagellum. Hydrodynamic flow across the asymmetrically shaped cell body translates into its rotational movement. Importantly, the presence of particles with the shape, size and spacing of blood cells is required and sufficient for trypanosomes to reach maximum forward velocity. If the density of obstacles, however, is further increased to resemble collagen networks or tissue spaces, the parasites reverse their flagellar beat and consequently swim backwards, in this way avoiding getting trapped. In the absence of obstacles, this flagellar beat reversal occurs randomly resulting in irregular waveforms and apparent cell tumbling. Thus, the swimming behavior of trypanosomes is a surprising example of micro-adaptation to life at low Reynolds numbers. For a precise physical interpretation, we compare our high-resolution microscopic data to results from a simulation technique that combines the method of multi-particle collision dynamics with a triangulated surface model. The simulation produces a rotating cell body and a helical swimming path, providing a functioning simulation method for a

  3. 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.

  4. Typed combinators for generic traversal

    NARCIS (Netherlands)

    Lämmel, R.; Vonk, J.

    2001-01-01

    Lacking support for generic traversal, functional programming languages suffer from a scalability problem when applied to large-scale program transformation problems. As a solution, we introduce emph{functional strategies: typeful generic functions that not only can be applied to terms of any type,

  5. 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.

  6. 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...

  7. 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.

  8. Trypanosomes of the subgenus Megatrypanum from armadillos (Xenarthra: Dasypodidae

    Directory of Open Access Journals (Sweden)

    T. V. Barrett

    1990-12-01

    Full Text Available A new species of trypanosome, Trypanosoma (Megatrypanum peba, is described from the peripheral blood of the armadillo Euphractus sexcinctus setosus from Bahia State, Brazil. Ten out of 29 specimens of the armadillo Dasypus novemcinctus from Pará State were found to have trypanosomes, including epimastigote forms, in impression smears of subcutaneous lymph nodes. The trypanosomes from D. novemcinctus are illustrated and were identified a idenrified as belonging to the subgenus Megatrypanum on the basis of their general appearance, although they failed to multiply is blood-agar culture medium and no bloodstream forms were seen. This is the first published record of trypanosomes of this subgenus from armdillos and the first demonstration of epimastigote trypanosomes in the mammalian host other than in the bloodstream, or in the anal glands of opssums.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. Immunobiology of African Trypanosomes: Need of Alternative Interventions

    Directory of Open Access Journals (Sweden)

    Toya Nath Baral

    2010-01-01

    Full Text Available Trypanosomiasis is one of the major parasitic diseases for which control is still far from reality. The vaccination approaches by using dominant surface proteins have not been successful, mainly due to antigenic variation of the parasite surface coat. On the other hand, the chemotherapeutic drugs in current use for the treatment of this disease are toxic and problems of resistance are increasing (see Kennedy (2004 and Legros et al. (2002. Therefore, alternative approaches in both treatment and vaccination against trypanosomiasis are needed at this time. To be able to design and develop such alternatives, the biology of this parasite and the host response against the pathogen need to be studied. These two aspects of this disease with few examples of alternative approaches are discussed here.

  14. Approaches for functional analysis of flagellar proteins in African trypanosomes.

    Science.gov (United States)

    Oberholzer, Michael; Lopez, Miguel A; Ralston, Katherine S; Hill, Kent L

    2009-01-01

    The eukaryotic flagellum is a highly conserved organelle serving motility, sensory, and transport functions. Although genetic, genomic, and proteomic studies have led to the identification of hundreds of flagellar and putative flagellar proteins, precisely how these proteins function individually and collectively to drive flagellum motility and other functions remains to be determined. In this chapter we provide an overview of tools and approaches available for studying flagellum protein function in the protozoan parasite Trypanosoma brucei. We begin by outlining techniques for in vitro cultivation of both T. brucei life cycle stages, as well as transfection protocols for the delivery of DNA constructs. We then describe specific assays used to assess flagellum function including flagellum preparation and quantitative motility assays. We conclude the chapter with a description of molecular genetic approaches for manipulating gene function. In summary, the availability of potent molecular tools, as well as the health and economic relevance of T. brucei as a pathogen, combine to make the parasite an attractive and integral experimental system for the functional analysis of flagellar proteins. PMID:20409810

  15. Download - Trypanosomes Database | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available Trypanosomes Database Download First of all, please read the license of this database. Data names and data d...escriptions are about the downloadable data in this page. They might not correspond to the contents of the o...ta name File Simple search and download 1 README README_e.html - 2 Protein trypanosome.zip (1.4 KB) Simple search and download... Downlaod via FTP Joomla SEF URLs by Artio About This Database Database Description Download... License Update History of This Database Site Policy | Contact Us Download - Trypanosomes Database | LSDB Archive ...

  16. Trypanosomes of Australian Mammals: Knowledge Gaps Regarding Transmission and Biosecurity.

    Science.gov (United States)

    Thompson, Craig K; Thompson, R C Andrew

    2015-11-01

    Trypanosomes infect humans, domestic animals, and wildlife, and are transmitted by haematophagous invertebrate vectors. Eight native trypanosome species have been described from Australian indigenous mammals, along with other unnamed isolates and genotypes. Associated difficulties relating to the confirmation of cyclical and mechanical vector candidates has hindered vector identification in Australia, with no successful experimental transmission documented for any of these native trypanosomes to indigenous mammals. We discuss pending biosecurity issues, with significant importance placed on the close phylogenetic and phenotypic relationship shared between Trypanosoma cruzi and some Australian trypanosomes. With such a dearth of information, we highlight the importance of keeping an open mind, which considers all possibilities during future investigations of vectors and their associated biosecurity issues in Australia.

  17. 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...

  18. Typed generic traversals in $S_gamma^'$

    NARCIS (Netherlands)

    Lämmel, R.

    2001-01-01

    A typed model of strategic rewriting is developed. An innovation is that generic traversals are covered. To this end, we define a rewriting calculus $S'_{gamma$. The calculus offers a few strategy combinators for generic traversals. There is, for example, a combinator to apply a strategy to all imme

  19. 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

  20. 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

  1. 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).

  2. 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;

    2009-01-01

    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 determined...... with late stage human African trypanosomiasis were associated with somnolence, low body weight, and trypanosomes in the cerebrospinal fluid. CONCLUSION: IFN-gamma-dependent CXCL10 is critical for accumulation of T cells and trypanosomes in the brain during experimental African trypanosomiasis. Data suggest...

  3. 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.

  4. First-class rules and generic traversal

    NARCIS (Netherlands)

    Dolstra, E.; Visser, Eelco

    2002-01-01

    In this paper we present a functional language supporting first-class rules and generic traversal. This is achieved by generalizing the pattern matching constructs of standard functional languages. The case construct that ties rules together and prevents their reuse, is replaced by separate, firstcl

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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 ...

  10. Weak measurement and the traversal time problem

    OpenAIRE

    Iannaccone, G.

    1996-01-01

    The theory of weak measurement, proposed by Aharonov and coworkers, has been applied by Steinberg to the long-discussed traversal time problem. The uncertainty and ambiguity that characterize this concept from the perspective of von Neumann measurement theory apparently vanish, and joint probabilities and conditional averages become meaningful concepts. We express the Larmor clock and some other well-known methods in the weak measurement formalism. We also propose a method to determine higher...

  11. 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...

  12. 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.

  13. Identification of different trypanosome species in the mid-guts of tsetse flies of the Malanga (Kimpese sleeping sickness focus of the Democratic Republic of Congo

    Directory of Open Access Journals (Sweden)

    Simo Gustave

    2012-09-01

    Full Text Available Abstract Background The Malanga sleeping sickness focus of the Democratic Republic of Congo has shown an epidemic evolution of disease during the last century. However, following case detection and treatment, the prevalence of the disease decreased considerably. No active survey has been undertaken in this focus for a couple of years. To understand the current epidemiological status of sleeping sickness as well as the animal African trypanosomiasis in the Malanga focus, we undertook the identification of tsetse blood meals as well as different trypanosome species in flies trapped in this focus. Methods Pyramidal traps were use to trap tsetse flies. All flies caught were identified and live flies were dissected and their mid-guts collected. Fly mid-gut was used for the molecular identification of the blood meal source, as well as for the presence of different trypanosome species. Results About 949 Glossina palpalis palpalis were trapped; 296 (31.2% of which were dissected, 60 (20.3% blood meals collected and 57 (19.3% trypanosome infections identified. The infection rates were 13.4%, 5.1%, 3.5% and 0.4% for Trypanosoma congolense savannah type, Trypanosoma brucei s.l., Trypanosoma congolense forest type and Trypanosoma vivax, respectively. Three mixed infections including Trypanosoma brucei s.l. and Trypanosoma congolense savannah type, and one mixed infection of Trypanosoma vivax and Trypanosoma congolense savannah type were identified. Eleven Trypanosoma brucei gambiense infections were identified; indicating an active circulation of this trypanosome subspecies. Of all the identified blood meals, about 58.3% were identified as being taken on pigs, while 33.3% and 8.3% were from man and other mammals, respectively. Conclusion The presence of Trypanosoma brucei in tsetse mid-guts associated with human blood meals is indicative of an active transmission of this parasite between tsetse and man. The considerable number of pig blood meals combined

  14. 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

  15. 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.

  16. 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.

  17. Mangiferin and its traversal into the brain.

    Science.gov (United States)

    Zajac, Dominika; Stasinska, Agnieszka; Delgado, Rene; Pokorski, Mieczyslaw

    2013-01-01

    Mangiferin, the main active substance of the mango tree bark (Mangifera indica L.), is known for its use in natural medicine, not only as a health enhancing panacea or adjunct therapeutic, but also for brain functions improvement. In this context, we deemed it worthwhile to establish whether mangiferin could traverse into the brain after systemic administration; an essential piece of information for the rational use of a compound as a neurotherapeutic, remaining so far inconclusive regarding mangiferin. We addressed this issue by studying recoverability of mangiferin in membrane and cytosolic fractions of rat brain homogenates after its intraperitoneal administration in a dose of 300 mg/kg. We used three preparations of mangiferin of decreasing purity to find out whether its penetration to the brain could have to do with the possible presence of contaminants. The qualitative methods of thin-layered-chromatography and UV/VIS spectrophotometry were employed in this study. The results were clearly negative, as we failed to trace mangiferin in the brain fractions with either method, which makes it unlikely that the compound traverse the blood-brain barrier after being systemically administered. We conclude that it is improbable that mangiferin could act via direct interaction with central neural components, but rather has peripheral, target specific functions which could be secondarily reflected in brain metabolism.

  18. Glossina spp. gut bacterial flora and their putative role in fly-hosted trypanosome development

    Directory of Open Access Journals (Sweden)

    Anne eGeiger

    2013-07-01

    Full Text Available Human African trypanosomiasis is caused by trypanosomes transmitted to humans by the tsetse fly, in which they accomplish their development into their infective metacyclic form. The crucial step in parasite survival occurs when it invades the fly midgut. Insect digestive enzymes and immune defenses may be involved in the modulation of the fly’s vector competence, together with bacteria that could be present in the fly’s midgut.In fact, in addition to the three bacterial symbionts that have previously been characterized, tsetse flies may harbor additional bacterial inhabitants. This review focuses on the diversity of the bacterial flora in Glossina, with regards to the fly species and their geographical distribution. The rationale was i that these newly identified bacteria, associated with tsetse flies, may contribute to vector competence as was shown in other insects and ii that differences may exist according to fly species and geographic area. A more complete knowledge of the bacterial microbiota of the tsetse fly and the role these bacteria play in tsetse biology may lead to novel ways of investigation in view of developing alternative anti-vector strategies for fighting human – and possibly animal – trypanosomiasis.

  19. Glossina spp. gut bacterial flora and their putative role in fly-hosted trypanosome development

    Science.gov (United States)

    Geiger, Anne; Fardeau, Marie-Laure; Njiokou, Flobert; Ollivier, Bernard

    2013-01-01

    Human African trypanosomiasis (HAT) is caused by trypanosomes transmitted to humans by the tsetse fly, in which they accomplish their development into their infective metacyclic form. The crucial step in parasite survival occurs when it invades the fly midgut. Insect digestive enzymes and immune defenses may be involved in the modulation of the fly's vector competence, together with bacteria that could be present in the fly's midgut. In fact, in addition to the three bacterial symbionts that have previously been characterized, tsetse flies may harbor additional bacterial inhabitants. This review focuses on the diversity of the bacterial flora in Glossina, with regards to the fly species and their geographical distribution. The rationale was (i) that these newly identified bacteria, associated with tsetse flies, may contribute to vector competence as was shown in other insects and (ii) that differences may exist according to fly species and geographic area. A more complete knowledge of the bacterial microbiota of the tsetse fly and the role these bacteria play in tsetse biology may lead to novel ways of investigation in view of developing alternative anti-vector strategies for fighting human—and possibly animal—trypanosomiasis. PMID:23898466

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

    Lifescience Database Archive (English)

    Full Text Available Trypanosomes Database License License to Use This Database Last updated : 2014/02/04 You may use this database...ense terms regarding the use of this database and the requirements you must follow in using this database.... The license for this database is specified in the Creative Commons Attribution-Sha...re Alike 2.1 Japan . If you use data from this database, please be sure attribute this database as follows: ...e . With regard to this database, you are licensed to: freely access part or whole of this database, and acq

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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...

  11. 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...p://www.tanpaku.org/tdb/ ) is opened. Joomla SEF URLs by Artio About This Database Database Description Download License Update... History of This Database Site Policy | Contact Us Update History of This Database - Trypanosomes Database | LSDB Archive ...

  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. 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

  1. 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)

  2. Population Genetics and Reproductive Strategies of African Trypanosomes: Revisiting Available Published Data.

    Directory of Open Access Journals (Sweden)

    Mathurin Koffi

    Full Text Available Trypanosomatidae are a dangerous family of Euglenobionta parasites that threaten the health and economy of millions of people around the world. More precisely describing the population biology and reproductive mode of such pests is not only a matter of pure science, but can also be useful for understanding parasite adaptation, as well as how parasitism, specialization (parasite specificity, and complex life cycles evolve over time. Studying this parasite's reproductive strategies and population structure can also contribute key information to the understanding of the epidemiology of associated diseases; it can also provide clues for elaborating control programs and predicting the probability of success for control campaigns (such as vaccines and drug therapies, along with emergence or re-emergence risks. Population genetics tools, if appropriately used, can provide precise and useful information in these investigations. In this paper, we revisit recent data collected during population genetics surveys of different Trypanosoma species in sub-Saharan Africa. Reproductive modes and population structure depend not only on the taxon but also on the geographical location and data quality (absence or presence of DNA amplification failures. We conclude on issues regarding future directions of research, in particular vis-à-vis genotyping and sampling strategies, which are still relevant yet, too often, neglected issues.

  3. Population Genetics and Reproductive Strategies of African Trypanosomes: Revisiting Available Published Data

    Science.gov (United States)

    Séré, Modou; Bucheton, Bruno; Simo, Gustave; Njiokou, Flobert; Salim, Bashir; Kaboré, Jacques; MacLeod, Annette; Camara, Mamadou; Solano, Philippe; Belem, Adrien Marie Gaston; Jamonneau, Vincent

    2015-01-01

    Trypanosomatidae are a dangerous family of Euglenobionta parasites that threaten the health and economy of millions of people around the world. More precisely describing the population biology and reproductive mode of such pests is not only a matter of pure science, but can also be useful for understanding parasite adaptation, as well as how parasitism, specialization (parasite specificity), and complex life cycles evolve over time. Studying this parasite’s reproductive strategies and population structure can also contribute key information to the understanding of the epidemiology of associated diseases; it can also provide clues for elaborating control programs and predicting the probability of success for control campaigns (such as vaccines and drug therapies), along with emergence or re-emergence risks. Population genetics tools, if appropriately used, can provide precise and useful information in these investigations. In this paper, we revisit recent data collected during population genetics surveys of different Trypanosoma species in sub-Saharan Africa. Reproductive modes and population structure depend not only on the taxon but also on the geographical location and data quality (absence or presence of DNA amplification failures). We conclude on issues regarding future directions of research, in particular vis-à-vis genotyping and sampling strategies, which are still relevant yet, too often, neglected issues. PMID:26491968

  4. 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

  5. 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

  6. 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

  7. A Six Degrees of Freedom Dynamic Wire-Driven Traverse

    Directory of Open Access Journals (Sweden)

    2016-04-01

    Full Text Available A novel support mechanism for a wind tunnel model is designed, built, and demonstrated on an aerodynamic platform undergoing dynamic maneuvers, tested with periodic motions up to 20 Hz. The platform is supported by a 6-DOF (six degrees of freedom traverse that utilizes eight thin wires, each mounted to a servo motor with an in-line load cell to accurately monitor or control the platform motion and force responses. The system is designed such that simultaneous control of the servo motors effects motion within ±50 mm translations, ±15° pitch, ±9° yaw, and ±8° roll at lower frequencies. The traverse tracks a desired trajectory and resolves the induced forces on the platform at 1 kHz. The effected motion of the platform is measured at 0.6 kHz with a motion capture system, which utilizes six near-infrared (NIR cameras for full spatial and temporal resolution of the platform motion, which is used for feedback control. The traverse allows different platform model geometries to be tested, and the present work demonstrates its capabilities on an axisymmetric bluff body. Programmable timed outputs are synchronized relative to the model motion and can be used for triggering external systems and processes. In the present study, particle image velocimetry (PIV is used to characterize the realized wakes of the platform undergoing canonical motions that are effected by this new wind tunnel traverse.

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

    DEFF Research Database (Denmark)

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

    2007-01-01

    Trypanosome lytic factor (TLF) is a high-density lipoprotein (HDL) subclass providing innate protection to humans against infection by the protozoan parasite Trypanosoma brucei brucei. Two primate-specific plasma proteins, haptoglobin-related protein (Hpr) and apolipoprotein L-1 (ApoL-1), have be...

  9. Isolation and phylogenetic relationships of bat trypanosomes from different biomes in Mato Grosso, Brazil.

    Science.gov (United States)

    Marcili, Arlei; da Costa, Andrea P; Soares, Herbert S; Acosta, Igor da C L; de Lima, Julia T R; Minervino, Antonio H H; Melo, Andréia T L; Aguiar, Daniel M; Pacheco, Richard C; Gennari, Solange M

    2013-12-01

    In the order Chiroptera, more than 30 trypanosome species belonging to the subgenera Herpetosoma, Schizotrypanum, Megatrypanum, and Trypanozoon have been described. The species Trypanosoma cruzi , Trypanosoma cruzi marinkellei, and Trypanosoma dionisii are the most common in bats and belong to the Schizotrypanum subgenus. Bats from 2 different biomes, Pantanal and Amazonia/Cerrado in the state of Mato Grosso, Brazil, were evaluated according to the presence of trypanosome parasites by means of hemoculture and PCR in primary samples (blood samples). A total of 211 bats from 20 different species were caught and the trypanosome prevalence, evaluated through hemoculture, was 9.0% (19), 15.5% (13), and 4.8% (6) in the municipalities of Confresa (Amazonia/Cerrado biome) and Poconé (Pantanal biome). Among the 123 primary samples obtained from the bats, only 3 (2.4%) were positive. Phylogenetic analysis using trypanosomatid barcoding (V7V8 region of SSU rDNA) identified all the isolates and primary samples as T. c. marinkellei. The sequences of the isolates were segregated according to the bat host genus or species and suggest that co-evolutionary patterns exist between hosts and parasites. Further studies in different Brazilian regions and biomes need to be conducted in order to gain real understanding of the diversity of trypanosomes in bats.

  10. 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

  11. Specific Cell Targeting Therapy Bypasses Drug Resistance Mechanisms in African Trypanosomiasis

    Science.gov (United States)

    Unciti-Broceta, Juan D.; Arias, José L.; Maceira, José; Soriano, Miguel; Ortiz-González, Matilde; Hernández-Quero, José; Muñóz-Torres, Manuel; de Koning, Harry P.; Magez, Stefan; Garcia-Salcedo, José A.

    2015-01-01

    African trypanosomiasis is a deadly neglected disease caused by the extracellular parasite Trypanosoma brucei. Current therapies are characterized by high drug toxicity and increasing drug resistance mainly associated with loss-of-function mutations in the transporters involved in drug import. The introduction of new antiparasitic drugs into therapeutic use is a slow and expensive process. In contrast, specific targeting of existing drugs could represent a more rapid and cost-effective approach for neglected disease treatment, impacting through reduced systemic toxicity and circumventing resistance acquired through impaired compound uptake. We have generated nanoparticles of chitosan loaded with the trypanocidal drug pentamidine and coated by a single domain nanobody that specifically targets the surface of African trypanosomes. Once loaded into this nanocarrier, pentamidine enters trypanosomes through endocytosis instead of via classical cell surface transporters. The curative dose of pentamidine-loaded nanobody-chitosan nanoparticles was 100-fold lower than pentamidine alone in a murine model of acute African trypanosomiasis. Crucially, this new formulation displayed undiminished in vitro and in vivo activity against a trypanosome cell line resistant to pentamidine as a result of mutations in the surface transporter aquaglyceroporin 2. We conclude that this new drug delivery system increases drug efficacy and has the ability to overcome resistance to some anti-protozoal drugs. PMID:26110623

  12. Discovery of a Carbazole-Derived Lead Drug for Human African Trypanosomiasis.

    Science.gov (United States)

    Thomas, Sarah M; Purmal, Andrei; Pollastri, Michael; Mensa-Wilmot, Kojo

    2016-01-01

    The protozoan parasite Trypanosoma brucei causes the fatal illness human African trypanosomiasis (HAT). Standard of care medications currently used to treat HAT have severe limitations, and there is a need to find new chemical entities that are active against infections of T. brucei. Following a "drug repurposing" approach, we tested anti-trypanosomal effects of carbazole-derived compounds called "Curaxins". In vitro screening of 26 compounds revealed 22 with nanomolar potency against axenically cultured bloodstream trypanosomes. In a murine model of HAT, oral administration of compound 1 cured the disease. These studies established 1 as a lead for development of drugs against HAT. Pharmacological time-course studies revealed the primary effect of 1 to be concurrent inhibition of mitosis coupled with aberrant licensing of S-phase entry. Consequently, polyploid trypanosomes containing 8C equivalent of DNA per nucleus and three or four kinetoplasts were produced. These effects of 1 on the trypanosome are reminiscent of "mitotic slippage" or endoreplication observed in some other eukaryotes. PMID:27561392

  13. 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

  14. 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.

  15. 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.

  16. Clustering for Improved Learning in Maze Traversal Problem

    CERN Document Server

    White, Eddie

    2009-01-01

    The maze traversal problem (finding the shortest distance to the goal from any position in a maze) has been an interesting challenge in computational intelligence. Recent work has shown that the cellular simultaneous recurrent neural network (CSRN) can solve this problem for simple mazes. This thesis focuses on exploiting relevant information about the maze to improve learning and decrease the training time for the CSRN to solve mazes. Appropriate variables are identified to create useful clusters using relevant information. The CSRN was next modified to allow for an additional external input. With this additional input, several methods were tested and results show that clustering the mazes improves the overall learning of the traversal problem for the CSRN.

  17. 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...

  18. Rapid Separation of Disconnected Triangle Meshes Based on Graph Traversal

    Energy Technology Data Exchange (ETDEWEB)

    Ji, S J; Wang, Y [Department of Mechanical Manufacturing and Automation, Harbin Institute of Technology, Harbin, 150001 (China)

    2006-10-15

    In recent year, The STL file become a de facto standard on the file presentation in CAD/CAM, computer graph and reverse engineering. When point cloud which is obtained by scanning object body using optical instrument is used to reconstruct an original model, the points cloud is presented by the STL file. Usually, datum of several separated and relative objects are stored in a single STL file, when such a file is operated by a computer, the datum in the file is firstly separated and then each element of every triangle pitch on the triangle mesh is traversed and visited and is calculated. The problem is analyzed and studied by many experts, but there is still a lack of a simple and quick algorithm. An algorithm which uses graph traversal to traverse each element of the triangle meshes and separate several disconnected triangle meshes is presented by the paper, the searching and calculating speed of the data on the triangle meshes is enhanced, memory size of the computer is reduced, complexity of the data structure is simplified and powerful guarantee is made for the next process by using this algorithm.

  19. Geometric structure of the generic static traversable wormhole throat

    Science.gov (United States)

    Hochberg, David; Visser, Matt

    1997-10-01

    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 two-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, when suitably weighted and integrated over the wormhole throat, must be violated.) The major technical limitation of the current approach is that we work in a static spacetime; this is already a quite rich and complicated system.

  20. 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...

  1. 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.

  2. The bacterial flora of tsetse fly midgut and its effect on trypanosome transmission

    OpenAIRE

    Soumana, I. H.; Simo, G.; Njiokou, F.; Tchicaya, B.; Abd-Alla, A.M.M.; Cuny, Gérard; Geiger, Anne

    2013-01-01

    The tsetse fly, Glossina palpalis is a vector of the trypanosome that causes sleeping sickness in humans and nagana in cattle along with associated human health problems and massive economic losses. The insect is also known to carry a number of symbionts such as Sodalis, Wigglesworthia, Wolbachia whose effects on the physiology of the insect have been studied in depth. However, effects of other bacterial flora on the physiology of the host and vector competence have received little attention....

  3. 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

    the proportion of infections during an 8-week follow-up period and the ratio of mean hazards in an isometamidium treated versus untreated group, provided consistent results across the three villages. In Burka village, both indices demonstrated the presence of isometamidium resistance trypanosome infections while......, in Cheleleki and Kolu villages, both indices did not indicate significant levels of resistance. There were significant differences between the Kaplan-Meier survival estimates of the control and treatment groups in Cheleleki (P 0.05)....

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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...

  10. Polarization of high-energy electrons traversing a laser beam

    CERN Document Server

    Kotkin, G L; Serbo, V G

    1998-01-01

    When polarized electrons traverse a region where the laser light is focused their polarization varies even if their energy and direction of motion are not changed. This effect is due to interference of the incoming electron wave and an electron wave scattered at zero angle. Equations are obtained which determine the variation of the electron density matrix, and their solutions are given. The change in the electron polarization depends not only on the Compton cross section but on the real part of the forward Compton amplitude as well. It should be taken into account, for example, in simulations of the $e \\to \\gamma$ conversion for future $\\gamma \\gamma$ colliders.

  11. 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.

  12. 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.

  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. Polarization of high-energy electrons traversing a laser beam

    Energy Technology Data Exchange (ETDEWEB)

    Kotkin, G.L.; Serbo, V.G. [Novosibirsk State Univ. (Russian Federation). Phys. Dept.; Perlt, H. [Institut fuer Theoretische Physik, Leipzig University, 04109, Leipzig, BRD (Germany)

    1998-02-21

    When polarized electrons traverse a region where the laser light is focused their polarization varies even if their energy and direction of motion are not changed. This effect is due to interference of the incoming electron wave and an electron wave scattered at zero angle. Equations are obtained which determine the variation of the electron-density matrix, and their solutions are given. The change in the electron polarization depends not only on the Compton cross section but on the real part of the forward Compton amplitude as well. It should be taken into account, for example, in simulations of the e{yields}{gamma} conversion for future {gamma}{gamma} colliders. (orig.). 16 refs.

  16. 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

  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. Operational vibroseis system for long-distance traverses

    Science.gov (United States)

    Eisen, Olaf; Hofstede, Coen; Diez, Anja; Kristoffersen, Yngve; Lambrecht, Astrid; Mayer, Christoph; Blenkner, Rick; Hilmarsson, Sverrir

    2014-05-01

    This poster presents results and performance of an operational vibroseis system used in Antarctica on the Ekströmisen and its catchment area. The about 500 km long overland traverse covered very different surface regimes in the elevation range from sea level up to 1000 m in the austral season 2013/14. The presentation is the successful culmination of a six-year effort to develop an operational vibroseis system for Antarctica and Greenland. Over three weeks the campaign acquired: • 407 km of seismic profiles in total, thereof • 110 km in 6-fold resolution with 125 m shot spacing • 25 km in 3-fold resolution with 250 m shot spacing. The remaining distance was covered in single-fold with 750 m shot spacing. The traverse used a well-established 60 channel 1.5 km streamer and a new setup with a vibroseis Buggy "EnviroVibe" with Mattracks on a polyethylen sled. The sled had a hole in the center to lower the vibrator pad directly onto the snow surface. With this setup data production varied between 20 km/day for 6-fold and 40 km/day for single fold for a decent 9h day of measurements. The combination of Mattracks with the PE-sled was especially advantageous on hard and rough surfaces because of the flexibility of each and the relatively lose mounting by cargo straps and wooden blocks. Production speeds were limited by the snow streamer, which had an increasing damage rate of geophone groups for velocities above 6 km/h. The source system itself could easily accommodate transfer velocities of 15 km/h. In combination with the streamer winch mounted in front of the source on a separate freight sled the channel spacing could be reduced to fractions of the 25 m spacing interval by combining several sweeps at the same location, thus increasing spatial resolution. The vibrator source was operated with a 10-250 Hz sweep over 10 s with 80% of the peak force of 66 kN. On soft surfaces a setup-sweep was utilized. Preliminary data analysis shows that sea floor geomorphology

  19. Anti-trypanosomal effect of Peristrophe bicalyculata extract on Trypanosoma brucei brucei-infected rats

    Institute of Scientific and Technical Information of China (English)

    Abdulazeez Mansurah Abimbola; Ibrahim Abdulrazak Baba; Edibo Zakari Yenusa; Sidali Joseph Omanibe; Idris Habeeb Oladimeji

    2013-01-01

    Objective: To investigate the in vitro and in vivo effect of whole plant extracts of Peristrophe bicalyculata on Trypanosoma brucei brucei-infected rats. Methods: The experiment was divided into two phases: In the first phase, the anti-trypanosomal activity of the hot water, cold water, methanol and butanol extracts of the whole plant were determined by incubating with Trypanosoma brucei brucei. The cold water extract was partially-purified and the anti-trypanosomal activity of the fractions determined. In the second phase, Trypanosoma brucei brucei-infected rats were treated with fraction 2c for nine days. Packed cell volume (PCV), high density lipoprotein (HDL), low density lipoprotein (LDL), total cholesterol (TC), triacylglycerol (TAG), aspartate aminotransferase, alanine aminotransferases (ALT), alkaline phosphatase (ALP), total and direct bilirubin levels were determined at the end of the experiment. Results:Cold water extract immobilized 90%of the parasites after 60 min of incubation, and fraction 2c completely immobilized the parasites after 35 min. It significantly increased PCV in Trypanosoma brucei brucei-infected rats. Decreased TC, TAG, HDL and LDL levels of infected rats increased significantly when rats were treated with the fraction, while elevated levels of total bilirubin and ALT also decreased. The difference in urea, direct bilirubin and ALP was not significant when infected rats were compared to rats in other groups. Conclusions:The ability of the plant to ameliorate the infection-induced biochemical changes calls for detailed investigation of the potentials of the plant for antitrypanosomiasis drug delivery.

  20. 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

  1. A Distributed Election and Spanning Tree Algorithm Based on Depth First Search Traversals

    DEFF Research Database (Denmark)

    Skyum, Sven

    The existence of an effective distributed traversal algorithm for a class of graphs has proven useful in connection with election problems for those classes. In this paper we show how a general traversal algorithm, such as depth first search, can be turned into an effective election algorithm usi...... modular techniques. The presented method also constructs a spanning tree for the graph....

  2. 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...

  3. 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.

  4. Inferences of Strength of Soil Deposits Along MER Rover Traverses

    Science.gov (United States)

    Richter, L. O.

    2005-12-01

    As the two Mars Exploration Rovers 'Spirit' and 'Opportunity' traverse terrains within Gusev crater and at Meridiani Planum, respectively, they leave behind wheel tracks that are routinely imaged by the different sets of cameras as part of the MER Athena instrument suite. Stereo observations of these tracks reveal wheel rut depths which are diagnostic of the strength of the soil-like deposits crossed by the vehicles. This contribution will discuss results of systematic analyses of MER-A and -B wheel sinkage measurements with regard to solutions for soil bearing strength, cohesion, and friction angle, occurring in the context of a suite of physical properties studies that are part of the Athena science investigation. Sinkage data are analyzed with wheel-soil theory calibrated to the shape of the MER wheel while accounting for wheel slip and by consulting comparisons with terrestrial soils. Results are applicable to the top ~20 to 30 cm of the soil deposits 'sampled' by normal stresses incurred from the wheels. The large number of wheel track observations per distance travelled enables investigations of variations of soil physical properties as a function of spatial scale, type of surface feature encountered, and local topography. Exploiting relationships between soil strength and degree of soil consolidation known from lunar regolith and dry terrestrial soils allows one to relate inferred soil strengths to bulk density which in turn is related to dielectric properties and to fine-component thermal inertia, both of which have been constrained for the two MER landing sites by remote sensing with comparatively coarse spatial resolution. In the context of the Athena science investigation, physical properties studies contribute to an overall understanding of the geology at the landing sites as they i) allow comparisons to be made between physical and compositional properties, ii) support attempts to correlate materials with geologic units, iii) help identify

  5. 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

  6. 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.

  7. Surface Albedo Variations Across Opportunity's Traverse in Meridiani Planum

    Science.gov (United States)

    Studer-Ellis, G. L.; Rice, M. S.; Johnson, J. R.; Bell, J. F., III

    2015-12-01

    Surface albedo measurements from the Mars Exploration Rover (MER) Opportunity mission can be used to help understand surface-atmosphere interactions at Meridiani Planum. Opportunity has acquired 117 albedo panoramas with the Pancam instrument as of sol 3870, across the first 40 km of its traverse. To date, only the first 32 panoramas have been reported upon in previous studies [1]. Here we present an analysis of the full set of PDS-released albedo observations from Opportunity and correlate our measurements with terrain type and known atmospheric events. To acquire a 360-degree albedo observation, Pancam's L1 ("clear") filter is used to take 27 broad-spectrum images, which are stitched into a mosaic. Pancam images are calibrated to reflectance factor (R*), which is taken as an approximation of the Lambertian albedo. Areas of interest are selected and average albedo calculations are applied to all of the selections. Results include the average albedo of each scene, as well as equal-area corrections where applicable, in addition to measurements of specific classes of surface features (e.g., outcrops, dusty terrain, and rover tracks). Average scene albedo measurements range from 0.11 ± 0.04 to 0.30 ± 0.04, with the highest value observed on sol 1290 (immediately after the planet-encircling dust storm of 2007). We compare these results to distance traveled, surface morphologies, local wind driven events, and dust opacity measurements. Future work will focus on correlating Pancam albedo values with orbital data from cameras such as HiRISE, CTX, MOC, THEMIS-VIS, and MARCI, and completion of the same analysis for the full Pancam albedo dataset from Spirit. References: [1] Bell, J. F., III, M. S. Rice, J. R. Johnson, and T. M. Hare (2008), Surface albedo observations at Gusev Crater and Meridiani Planum, Mars, J. Geophys. Res., 113, E06S18, doi:10.1029/2007JE002976.

  8. 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.

  9. 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.

  10. The krebs cycle enzyme α-ketoglutarate decarboxylase is an essential glycosomal protein in bloodstream African trypanosomes.

    Science.gov (United States)

    Sykes, Steven; Szempruch, Anthony; Hajduk, Stephen

    2015-03-01

    α-Ketoglutarate decarboxylase (α-KDE1) is a Krebs cycle enzyme found in the mitochondrion of the procyclic form (PF) of Trypanosoma brucei. The bloodstream form (BF) of T. brucei lacks a functional Krebs cycle and relies exclusively on glycolysis for ATP production. Despite the lack of a functional Krebs cycle, α-KDE1 was expressed in BF T. brucei and RNA interference knockdown of α-KDE1 mRNA resulted in rapid growth arrest and killing. Cell death was preceded by progressive swelling of the flagellar pocket as a consequence of recruitment of both flagellar and plasma membranes into the pocket. BF T. brucei expressing an epitope-tagged copy of α-KDE1 showed localization to glycosomes and not the mitochondrion. We used a cell line transfected with a reporter construct containing the N-terminal sequence of α-KDE1 fused to green fluorescent protein to examine the requirements for glycosome targeting. We found that the N-terminal 18 amino acids of α-KDE1 contain overlapping mitochondrion- and peroxisome-targeting sequences and are sufficient to direct localization to the glycosome in BF T. brucei. These results suggest that α-KDE1 has a novel moonlighting function outside the mitochondrion in BF T. brucei.

  11. 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...

  12. 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

  13. Phenotypic characteristics and trypanosome prevalence of Mursi cattle breed in the Bodi and Mursi districts of South Omo Zone, southwest Ethiopia.

    Science.gov (United States)

    Terefe, Endashaw; Haile, Aynalem; Mulatu, Wudyalew; Dessie, Tadelle; Mwai, Okeyo

    2015-03-01

    The study was conducted to characterize the morphological features of Mursi cattle breed and to identify the species of trypanosome infecting the cattle and its prevalence in these traditionally managed cattle in the Bodi and Mursi pastoral communities. Cattle body description and measurements were made on 201 matured animals. Blood samples were collected from 409 animals into heparin-treated capillary tubes and were centrifuged to 12,000 rpm for 5 min to identify trypanosome species from the wet smeared buffy coat and to estimate the degree of anemia (PCV). Tsetse flies were collected using phenol-treated biconical trap and the caught flies identified to species level. The breed possesses variable coat color pattern, coat color type, and have small to medium hump size on the thoracic vertebrae. Body measurement of Mursi cattle in the two locations did not show significant differences except chest girth, rump width, and horn length. Trypanosome prevalence in the Mursi cattle breed was 6.1%. The highest trypanosome infection was caused by Trypanosoma congolense (56%) followed by Trypanosoma vivax (40%) and Trypanosoma brucei (4%). Trypanosome prevalence significantly varies between dry (2.0%) and late rainy (10.1%) seasons (P cattle show the lowest PCV value (20.4 ± 1%) than aparasitaemic (23.7 ± 0.3%) cattle and cattle with lean BCS showed the lowest (P cattle shows medium BCS, low trypanosome prevalence, and higher PCV value.

  14. 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.

  15. 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, ...

  16. 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.

  17. ANALYSIS OF TRAVERSE RIBBING EFFICIENCY IN MILLING PLANER WITH TRAVELING BRIDGES

    Directory of Open Access Journals (Sweden)

    V. I. Turomsha

    2011-01-01

    Full Text Available A finite element modeling of recoverable traverse deformations of heavy milling planers with traveling bridges has been carried out in the paper. The paper reveals specific deformation modes – twisting, bending and cross-section crabbing. Various variants of internal traverse ribbing have been investigated in the paper. The paper shows a ribbing influence on some deformation modes and its efficiency with double walls. Recommendations on provision of base components’ rigidity with material economical expenditure is given in the paper.

  18. Development and Use of Overland Traversing Capabilities As a Science Platform on the Greenland Ice Sheet

    Science.gov (United States)

    Mercer, J. L.; Haggerty, P.; Crain, R.; Olsen, R.; Burnside, J.; Wisneski, S.; Joyner, J.; Phillips, G.; Lever, J. H.; Weale, J.

    2012-12-01

    The National Science Foundation's Arctic Sciences Research Support and Logistics office, along with their prime support contractor (CH2MHill Polar Services) and the US Army Cold Regions Research and Engineering Laboratory (CRREL), has been developing heavy-haul overland traversing capabilities on the Greenland Ice Sheet since 2007. In the past 5 years, logistical, technological and environmental challenges have been overcome to develop efficient, well-functioning and safe traverse capabilities aimed at delivering fuel and cargo resupply to inland research stations. The next phase of this effort entails the development and implementation of science support using the traverse as a platform. With rapid changes occurring on the ice sheet, an increase in science interests over long sections of Greenland is anticipated. The traverse provides a potential platform for onboard instrumentation and integrated data collection systems, installation and routine maintenance of monitoring stations on the ice sheet, sample and data collection over transects along the ice sheet, or movement of large/heavy science equipment. This presentation will provide an overview and discussion of current and future traverse science support capabilities, as well as potential options for implementing science support using the traverse as a platform.

  19. Traversal Caches: A Framework for FPGA Acceleration of Pointer Data Structures

    Directory of Open Access Journals (Sweden)

    James Coole

    2010-01-01

    Full Text Available Field-programmable gate arrays (FPGAs and other reconfigurable computing (RC devices have been widely shown to have numerous advantages including order of magnitude performance and power improvements compared to microprocessors for some applications. Unfortunately, FPGA usage has largely been limited to applications exhibiting sequential memory access patterns, thereby prohibiting acceleration of important applications with irregular patterns (e.g., pointer-based data structures. In this paper, we present a design pattern for RC application development that serializes irregular data structure traversals online into a traversal cache, which allows the corresponding data to be efficiently streamed to the FPGA. The paper presents a generalized framework that benefits applications with repeated traversals, which we show can achieve between 7x and 29x speedup over pointer-based software. For applications without strictly repeated traversals, we present application-specialized extensions that benefit applications with highly similar traversals by exploiting similarity to improve memory bandwidth and execute multiple traversals in parallel. We show that these extensions can achieve a speedup between 11x and 70x on a Virtex4 LX100 for Barnes-Hut n-body simulation.

  20. 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

  1. Antarctic Exploration Parallels for Future Human Planetary Exploration: The Role and Utility of Long Range, Long Duration Traverses

    Science.gov (United States)

    Hoffman, Stephen J. (Editor); Voels, Stephen A. (Editor)

    2012-01-01

    Topics covered include: Antarctic Exploration Parallels for Future Human Planetary Exploration: Science Operations Lessons Learned, Planning, and Equipment Capabilities for Long Range, Long Duration Traverses; Parallels Between Antarctic Travel in 1950 and Planetary Travel in 2050 (to Accompany Notes on "The Norwegian British-Swedish Antarctic Expedition 1949-52"); My IGY in Antarctica; Short Trips and a Traverse; Geologic Traverse Planning for Apollo Missions; Desert Research and Technology Studies (DRATS) Traverse Planning; Science Traverses in the Canadian High Arctic; NOR-USA Scientific Traverse of East Antarctica: Science and Logistics on a Three-Month Expedition Across Antarctica's Farthest Frontier; A Notional Example of Understanding Human Exploration Traverses on the Lunar Surface; and The Princess Elisabeth Station.

  2. 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...

  3. The impact of host starvation on parasite development and population dynamics in an intestinal trypanosome parasite of bumble bees

    OpenAIRE

    Brown, Mark; RUIZ-GONZALEZ, MARIO XAVIER

    2005-01-01

    Host nutrition plays an important role in determining the development and success of parasitic infections. While studies of vertebrate hosts are accumulating, little is known about how host nutrition affects parasites of invertebrate hosts. Crithidia bombi is a gut trypanosome parasite of the bumble bee, Bombus terrestris and here we use it as a model system to determine the impact of host nutrition on the population dynamics and development of micro-parasites in invertebrates. Polle...

  4. Trypanosomes Infection in Field-Captured Tsetse Flies of the Subgenus: Nemorhina In Southern Guinea Savanna Zone of Nigeria

    Directory of Open Access Journals (Sweden)

    K.E. Okoh

    2012-11-01

    Full Text Available An investigation aimed at assessing the Trypanosomes infection in the Palpalis group was conducted between January and December of 2007 at Kamuku National Park, using Biconical and Nitse traps. Flies were trapped along riverine vegetation for two trapping days each month and were harvested daily. Out of 213 tsetse flies examined, 14 (6.6% were infected with trypanosome. Infection rate in G. tachinoides 9.4% (11 out of 117 were statistically (p<0.05 higher than G. Palpalis 3.1% (3 out of 96 flies examined. Also, infection rate were higher in males 5.2% (11 than females 1.4% (3. Infection due to Trypanosoma vivax 5.2% (11 dominated, followed by T. congolense 0.9% (2 then T. brucei 0.5% (1. The Mean Hunger Stages of 3.5 and 3.6 for G. tachinoides and G. palpalis respectively indicated a hungry population. Infections were highest in the month of May. The presence of Tsetse and Trypanosome infection in the park may pose public health risk.

  5. 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

  6. 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.

  7. "African Connection."

    Science.gov (United States)

    Adelman, Cathy; And Others

    This interdisciplinary unit provides students in grades kindergarten through seventh grade an opportunity to understand diversity through a study of Africa as a diverse continent. The project is designed to provide all elementary students with cultural enrichment by exposing them to African music, art, storytelling, and movement. This project can…

  8. 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.  

  9. 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.

  10. Accumulation rates in Northwest Greenland from continuous GPR profiling along the Greenland Inland Traverse

    Science.gov (United States)

    Hawley, R. L.; Courville, Z.; Kehrl, L. M.; Lutz, E.; Osterberg, E. C.; Overly, T. B.; Wong, G. J.

    2012-12-01

    Snow accumulation is one of the fundamental parameters governing the mass balance of the Greenland Ice Sheet. While many point measurements of accumulation exist from shallow and deep ice cores, there are few spatially extensive and continuous records of accumulation in Greenland, particularly in the northwest quadrant. In April and May 2011, the Greenland Inland Traverse traveled via tractor train from Thule Air Base in northwest Greenland to Summit Station, at the center of the ice sheet. The science team on the traverse collected both point and profile measurements along the route. Kinematic GPS and 400 MHz GPR profiles provide geolocated subsurface stratigraphy. Density measurements from snowpits and shallow cores on the profile allow us to determine the true depth of radar reflecting horizons, commonly interpreted to be isochrons. We use three ice cores collected at the beginning, the end, and roughly the middle of the route to date horizons. We traced strong reflecting horizons along the entire route. From the combination of dated, traced horizons, density measurements, and position measurements, we determine accumulation rates continuously along the traverse route. We find our traverse route begins in a high-accumulation area, and accumulation decreases as we cross to the east side of the summit ridge. Accumulation then climbs again as we approach summit (directly on the summit ridge). We compare our accumulation rates with previous studies, both measurements (traverse and point measurements) and models.

  11. 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.

  12. 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.

  13. Morphological Features of Trypanosomes from Squirrel Monkeys from the Brazilian Amazon

    Directory of Open Access Journals (Sweden)

    Mariangela Ziccardi

    1998-01-01

    Full Text Available A morphometric analysis of blood trypomastigotes identified as Trypanosoma minasense, T. saimirii, and T. rangeli harbored by squirrel monkeys from the Brazilian Amazon was performed. Additionally, morphological and biological comparative analyses were conducted of T. saimirii-like and T. rangeli development forms from haemoculture and xenodiagnosis. Illustrations are given of blood trypomastigotes as well as of developing flagellates in triatomine and axenic culture. Mean values of blood trypomastigotes of T. saimirii differ statistically from those of T. rangeli in only two out of ten morphological characters measured, and ranges overlapped. The developing forms of T. saimrii-like parasites were essentially identical in both xenodiagnosis and haemoculture to those of T. rangeli. Trypanosomes confirmed as T. rangeli were transmitted to mice by the bites of the great majority of triatomines that fed on T. saimirii-like infected monkeys. We conclude that, based on morphology and on the development in triatomine bugs and haemoculture, T. saimirii should not be considered a distinct species. We therefore propose T. saimirii to be a junior synonym of T. rangeli

  14. 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

  15. 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...

  16. Influence of traverse speed on surface irregularities created by the abrasive waterjet

    Directory of Open Access Journals (Sweden)

    J. Valíček

    2012-01-01

    Full Text Available The paper deals with the calculation of the optimal traverse speed for diff erent types of materials, which is very important for predication, imaginings and dimensioning of technological factors and selection of the materials with the aim to increase of surface quality at abrasive waterjet cutting (AWJ technology. The surface irregularities of the experimental used materials AISI 304, AISI 309 have been measured by non-contact shadow method. New empirically compiled equations of the infl uence of the traverse speed on tensometrical state of cut, deformation resistance of material and surface roughness Ra are at AWJ cutting available.

  17. 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...

  18. Immunophenotypic lymphocyte profiles in human african trypanosomiasis.

    Directory of Open Access Journals (Sweden)

    Caroline Boda

    Full Text Available Human African trypanosomiasis (HAT is a deadly vector-born disease caused by an extracellular parasite, the trypanosome. Little is known about the cellular immune responses elicited by this parasite in humans. We used multiparameter flow cytometry to characterize leukocyte immunophenotypes in the blood and cerebrospinal fluid (CSF of 33 HAT patients and 27 healthy controls identified during a screening campaign in Angola and Gabon. We evaluated the subsets and activation markers of B and T lymphocytes. Patients had a higher percentage of CD19+ B lymphocytes and activated B lymphocytes in the blood than did controls, but lacked activated CD4+ T lymphocytes (CD25+. Patients displayed no increase in the percentage of activated CD8+ T cells (HLA-DR+, CD69+ or CD25+, but memory CD8 T-cell levels (CD8+CD45RA2 were significantly lower in patients than in controls, as were effector CD8 T-cell levels (CD8+CD45RA+CD62L2. No relationship was found between these blood immunophenotypes and disease severity (stage 1 vs 2. However, CD19+ B-cell levels in the CSF increased with disease severity. The patterns of T and B cell activation in HAT patients suggest that immunomodulatory mechanisms may operate during infection. Determinations of CD19+ B-cell levels in the CSF could improve disease staging.

  19. 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 ...

  20. 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.

  1. Resolving the question of trypanosome monophyly: a comparative genomics approach using whole genome data sets with low taxon sampling.

    Science.gov (United States)

    Leonard, Guy; Soanes, Darren M; Stevens, Jamie R

    2011-07-01

    Since the first attempts to classify the evolutionary history of trypanosomes, there have been conflicting reports regarding their true phylogenetic relationships and, in particular, their relationships with other vertebrate trypanosomatids, e.g. Leishmania sp., as well as with the many insect parasitising trypanosomatids. Perhaps the issue that has provided most debate is that concerning the monophyly (or otherwise) of genus Trypanosoma and, even with the advent of molecular methods, the findings of numerous studies have varied significantly depending on the gene sequences analysed, number of taxa included, choice of outgroup and phylogenetic methodology. While of arguably limited applied importance, resolution of the question as to whether or not trypanosomes are monophyletic is critical to accurate evaluation of competing, mutually exclusive evolutionary scenarios for these parasites, namely the 'vertebrate-first' or 'insect-first' hypotheses. Therefore, a new approach, which could overcome previous limitations was needed. At its most simple, the problem can be defined within the framework of a trifurcated tree with three hypothetical positions at which the root can be placed. Using BLASTp and whole-genome gene-by-gene phylogenetic analyses of Trypanosoma brucei, Trypanosoma cruzi, Leishmania major and Naegleria gruberi, we have identified 599 gene markers--putative homologues--that were shared between the genomes of these four taxa. Of these, 75 homologous gene families that demonstrate monophyly of the kinetoplastids were identified. We then used these data sets in combination with an additional outgroup, Euglena gracilis, coupled with large-scale gene concatenation and diverse phylogenetic techniques to investigate the relative branching order of T. brucei, T. cruzi and L. major. Our findings confirm the monophyly of genus Trypanosoma and demonstrate that <1% of the analysed gene markers shared between the genomes of T. brucei, T. cruzi and L. major reject

  2. Geomorphic/Geologic Mapping, Localization, and Traverse Planning at the Opportunity Landing Site, Mars

    Science.gov (United States)

    Parker, T. J.; Golombek, M. P.; Powell, M. W.

    2010-03-01

    Mapping of the Opportunity traverse, using the project’s planning tool, “maestro”, and GIS software. Experience gained by the science and engineering teams will be invaluable for planning and conducting future mobile explorer missions to Mars and other planetary bodies.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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)

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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.

  17. 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

  18. 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)

  19. Site Selection and Automatically Calculated Rover Traverse for a Lunar Teleoperated Landing Mission

    Science.gov (United States)

    Kamps, Oscar; Foing, Bernard; Flahaut, Jessica

    2016-04-01

    With the recent interest for the Moon, and the plans from the ESA side to do a tele-operated mission from Earth or lunar orbit, it is important to target a well-defined location. One of the major topics to study on the Moon is the existence and availability of volatiles and ices. Because no lander ever visited one of the poles on the Moon the theories with respect to water ice are only based on data from orbiters. In a four month research project the data from the orbiters was used for assessing potential landing sites and a rover traverse planning. Mainly data from the Prospector and LRO were used to select regions of interest. The prior selection was based on slope, temperature and a geological map from the USGS. Three sites on both the North as South Pole were used to test a proposed method for rover traverse planning. Besides the scientific interest, the sites where assessed on its accessibility for landing and roving. This assessment was done based on some assumptions what would be possible for landing and roving. For landing sites it was proposed to pick a site larger than 1km in diameter, in a (partial) illuminated area with a slope lower than 5o, which was inside an area which would be accessible for a rover. The requirements to be selected as accessible area was a slope lower than 20o, the largest polygon which meets this requirement was chosen as accessible area. As destination a site in the PSR was selected which was inside the accessible area and had extremely low temperatures. The boundary for extremely low was defined as 54K which is the sublimation temperature of CO2 in lunar atmospheric pressure. As additional target for the rover a site was selected where the temperature difference would be more than 150K to study volatile migration processes. A combination of tools in ArcGIS were used to do the site selection and rover traverse planning. In the end Rozhdestvensky and Amundsen were selected as most accessible and interesting. After comparing both

  20. 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.

  1. Universal adaptive self-stabilizing traversal scheme: random walk and reloading wave

    CERN Document Server

    Bernard, Thibault; Sohier, Devan

    2011-01-01

    In this paper, we investigate random walk based token circulation in dynamic environments subject to failures. We describe hypotheses on the dynamic environment that allow random walks to meet the important property that the token visits any node infinitely often. The randomness of this scheme allows it to work on any topology, and require no adaptation after a topological change, which is a desirable property for applications to dynamic systems. For random walks to be a traversal scheme and to answer the concurrence problem, one needs to guarantee that exactly one token circulates in the system. In the presence of transient failures, configurations with multiple tokens or with no token can occur. The meeting property of random walks solves the cases with multiple tokens. The reloading wave mechanism we propose, together with timeouts, allows to detect and solve cases with no token. This traversal scheme is self-stabilizing, and universal, meaning that it needs no assumption on the system topology. We describ...

  2. 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...

  3. 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...

  4. A note on 4-dimensional traversable wormholes and energy conditions in higher dimensions

    CERN Document Server

    Kao, W F; Soo, Chopin

    2003-01-01

    We show explicitly that traversable wormholes requiring exotic matter in 4-dimensions nevertheless have acceptable stress-tensors obeying reasonable energy conditions in higher dimensions if the wormholes are regarded as being embedded in higher dimensional space-times satisfying Einstein's field equations. From the 4-dimensional perspective, the existence of higher dimensions may thus facilitate wormhole and time-machine constructions through access to "exotic matter".

  5. 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.

  6. 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 ...

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

    OpenAIRE

    Jonny Karlsson; Dooley, Laurence S.; Göran Pulkkis

    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 node...

  8. 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.

  9. 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

  10. 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

  11. Distributed Broker-Agent Architecture for Multimedia Communications Traversing NAT/Firewall in NGN

    Institute of Scientific and Technical Information of China (English)

    苟先太; 金炜东

    2004-01-01

    The forthcoming Next Generation Network (NGN) is an all IP network. Multimedia communications over IP networks are a type of bundled session communications, which cannot directly traverse Network Address Translations (NATs) and firewalls even in NGN. To solve the problem that the existing traversal methods are not suitable for service providers to set up a real system in NGN,a Distributed Broker-agent Architecture (DBA) is addressed. DBA is secure and realizable for service providers and enterprises because it is easy to set up and does not need to upgrade the existing devices like Firewalls, NATs or endpoint devices of subscribers.DBA is composed of two-layer distributed agents, the server proxies and the client agents, in which all multimedia communications use shared tunnels to carry signaling messages and media data between broker-agents, and the call signaling is encrypted over Security Socket Layer (SSL) to guarantee the security of calling. Moreover, the function model and multiplexed connection messages format of DBA are designed, which lays a basis for the protocol in the future NGN. In addition, a simple implementation based on H.323 verifyies the main function of traversing firewalls and NATs.

  12. Improvements on restricted insecticide application protocol for control of Human and Animal African Trypanosomiasis in eastern Uganda.

    Directory of Open Access Journals (Sweden)

    Dennis Muhanguzi

    2014-10-01

    Full Text Available BACKGROUND: African trypanosomes constrain livestock and human health in Sub-Saharan Africa, and aggravate poverty and hunger of these otherwise largely livestock-keeping communities. To solve this, there is need to develop and use effective and cheap tsetse control methods. To this end, we aimed at determining the smallest proportion of a cattle herd that needs to be sprayed on the legs, bellies and ears (RAP for effective Human and Animal African Trypanosomiasis (HAT/AAT control. METHODOLOGY/PRINCIPAL FINDING: Cattle in 20 villages were ear-tagged and injected with two doses of diminazene diaceturate (DA forty days apart, and randomly allocated to one of five treatment regimens namely; no treatment, 25%, 50%, 75% monthly RAP and every 3 month Albendazole drench. Cattle trypanosome re-infection rate was determined by molecular techniques. ArcMap V10.3 was used to map apparent tsetse density (FTD from trap catches. The effect of graded RAP on incidence risk ratios and trypanosome prevalence was determined using Poisson and logistic random effect models in R and STATA V12.1 respectively. Incidence was estimated at 9.8/100 years in RAP regimens, significantly lower compared to 25.7/100 years in the non-RAP regimens (incidence rate ratio: 0.37; 95% CI: 0.22-0.65; P<0.001. Likewise, trypanosome prevalence after one year of follow up was significantly lower in RAP animals than in non-RAP animals (4% vs 15%, OR: 0.20, 95% CI: 0.08-0.44; P<0.001. Contrary to our expectation, level of protection did not increase with increasing proportion of animals treated. CONCLUSIONS/SIGNIFICANCE: Reduction in RAP coverage did not significantly affect efficacy of treatment. This is envisaged to improve RAP adaptability to low income livestock keepers but needs further evaluation in different tsetse challenge, HAT/AAT transmission rates and management systems before adopting it for routine tsetse control programs.

  13. 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...

  14. 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

  15. 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...

  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. 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 ...

  18. 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

  19. 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

  20. The impact of host starvation on parasite development and population dynamics in an intestinal trypanosome parasite of bumble bees.

    Science.gov (United States)

    Logan, A; Ruiz-González, M X; Brown, M J F

    2005-06-01

    Host nutrition plays an important role in determining the development and success of parasitic infections. While studies of vertebrate hosts are accumulating, little is known about how host nutrition affects parasites of invertebrate hosts. Crithidia bombi is a gut trypanosome parasite of the bumble bee, Bombus terrestris and here we use it as a model system to determine the impact of host nutrition on the population dynamics and development of micro-parasites in invertebrates. Pollen-starved bees supported significantly smaller populations of the parasite. In pollen-fed bees the parasite showed a temporal pattern in development, with promastigote transmission stages appearing at the start of the infection and gradually being replaced by choanomastigote and amastigote forms. In pollen-starved bees this developmental process was disrupted, and there was no pattern in the appearance of these three forms. We discuss the implications of these results for parasite transmission, and speculate about the mechanisms behind these changes.

  1. 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

  2. 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 ...

  3. 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 ...

  4. Linguistic Imperialism: African Perspectives.

    Science.gov (United States)

    Phillipson, Robert

    1996-01-01

    Responds to an article on aspects of African language policy and discusses the following issues: multilingualism and monolingualism, proposed changes in language policy from the Organization for African Unity and South African initiatives, the language of literature, bilingual education, and whose interests English-language teaching is serving.…

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. Conformal and traversable wormholes with monopole and perfect fluid in f(R)-gravity

    Science.gov (United States)

    Taşer, Doǧukan; Doǧru, Melis Ulu

    2016-10-01

    We investigate spherically symmetric spacetime filled with global monopole and perfect fluid in f(R)-gravity. We consider field equations of f(R)-gravity in order to understand the global monopole and the perfect fluid curve to the spacetime. It has taken advantages of conformal symmetry properties of the spacetime to solve these equations. The obtained solutions are improved in case of phantom energy. It is shown that obtained f(R) function is consistent with well-known models of the modified gravity. Also, it is examined whether the obtained solutions support a traversable wormhole geometry. Obtained results of the solutions have been concluded.

  11. Evaluation of Robotic Systems to Carry Out Traverse Execution, Opportunistic Science, and Landing Site Evaluation Tasks

    Science.gov (United States)

    Hoffman, Stephen J.; Leonard, Matther J.; Pacal, Lee

    2011-01-01

    This report covers the execution of and results from the activities proposed and approved in Exploration Analogs and Mission Development (EAMD) Field Test Protocol HMP2010: Evaluation of Robotic Systems to carry out Traverse Execution, Opportunistic Science, and Landing Site Evaluation Tasks. The field tests documented in this report examine one facet of a larger program of planetary surface exploration. This program has been evolving and maturing for several years, growing from a broad policy statement with a few specified milestones for NASA to an international effort with much higher fidelity descriptions of systems and operations necessary to accomplish this type of exploration.

  12. 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.

  13. 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;

    2006-01-01

    , 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......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...

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. The Traverse Planning Process for the Drats 2010 Analog Field Simulations

    Science.gov (United States)

    Horz, Friedrich; Gruener, John; Lofgren, Gary; Skinner, James A., Jr.; Graf, Jodi; Seibert, Marc

    2011-01-01

    Traverse planning concentrates on optimizing the science return within the overall objectives of planetary surface missions or their analog field simulations. Such simulations were conducted in the San Francisco Volcanic Field, northern Arizona, from Aug. 26 to Sept 17, 2010 and involved some 200 individuals in the field, with some 40 geoscientists composing the science team. The purpose of these Desert Research and Technology Studies (DRATS) is to exercise and evaluate developmental hardware, software and operational concepts in a mission-like, fully-integrated, setting under the direction of an onsite Mobile Mission Control Center(MMCC). DRATS 2010 focused on the simultaneous operation of 2 rovers, a historic first. Each vehicle was manned by an astronaut-commander and an experienced field geologist. Having 2 rovers and crews in the field mandated substantially more complex science and mission control operations compared to the single rover DRATS tests of 2008 and 2009, or the Apollo lunar missions. For instance, the science support function was distributed over 2 "back rooms", one for each rover, with both "tactical" teams operating independently and simultaneously during the actual traverses. Synthesis and integration of the daily findings and forward planning for the next day(s) was accomplished overnight by yet another "strategic" science team.

  19. How terrestrial planets traverse spin-orbit resonances: A camel goes through a needle's eye

    CERN Document Server

    Makarov, Valeri V

    2011-01-01

    The dynamical evolution of terrestrial planets resembling Mercury in the vicinity of spin-orbit resonances is investigated using comprehensive harmonic expansions of the tidal torque with accurate expressions for the frequency-dependent quality factors and Love numbers. The torque equations are integrated numerically with a small step in time, taking into account the oscillating triaxial torque components but neglecting the layered structure of the planet and assuming a zero obliquity. We find that a Mercury-like planet with its current value of orbital eccentricity (0.2056) is always captured in the 3:2 resonance, and invariably traverses all higher resonances. The circumstances of a resonance passage are remarkable, in that it happens very quickly, in a sudden lunge. Considering the phase space parameters at the times of periastron, a Mercury-like planet can traverse the resonance only if its angle with respect to the star is close to $\\pm\\pi/2$, i.e., if the planet is positioned sidewise, with the longest ...

  20. Methods to determine the transcriptomes of trypanosomes in mixtures with mammalian cells: the effects of parasite purification and selective cDNA amplification.

    Directory of Open Access Journals (Sweden)

    Julius Mulindwa

    2014-04-01

    Full Text Available Patterns of gene expression in cultured Trypanosoma brucei bloodstream and procyclic forms have been extensively characterized, and some comparisons have been made with trypanosomes grown to high parasitaemias in laboratory rodents. We do not know, however, to what extent these transcriptomes resemble those in infected Tsetse flies - or in humans or cattle, where parasitaemias are substantially lower. For clinical and field samples it is difficult to characterize parasite gene expression because of the large excess of host cell RNA. We have here examined two potential solutions to this problem for bloodstream form trypanosomes, assaying transcriptomes by high throughput cDNA sequencing (RNASeq. We first purified the parasites from blood of infected rats. We found that a red blood cell lysis procedure affected the transcriptome substantially more than purification using a DEAE cellulose column, but that too introduced significant distortions and variability. As an alternative, we specifically amplified parasite sequences from a mixture containing a 1000-fold excess of human RNA. We first purified polyadenylated RNA, then made trypanosome-specific cDNA by priming with a spliced leader primer. Finally, the cDNA was amplified using nested primers. The amplification procedure was able to produce samples in which 20% of sequence reads mapped to the trypanosome genome. Synthesis of the second cDNA strand with a spliced leader primer, followed by amplification, is sufficiently reproducible to allow comparison of different samples so long as they are all treated in the same way. However, SL priming distorted the abundances of the cDNA products and definitely cannot be used, by itself, to measure absolute mRNA levels. The amplification method might be suitable for clinical samples with low parasitaemias, and could also be adapted for other Kinetoplastids and to samples from infected vectors.

  1. 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

  2. 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

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. 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.

  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. 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’.

  11. 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

  12. 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

  13. Identifying Time Measurement Tampering in the Traversal Time and Hop Count Analysis (TTHCA Wormhole Detection Algorithm

    Directory of Open Access Journals (Sweden)

    Jonny Karlsson

    2013-05-01

    Full Text Available 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.

  14. 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.

  15. The role of photogeologic mapping in traverse planning: lessons learned from DRATS 2010 activities

    Science.gov (United States)

    Skinner, James A.; Fortezzo, Corey M.

    2013-01-01

    We produced a 1:24,000 scale photogeologic map of the Desert Research and Technology Studies (DRATS) 2010 simulated lunar mission traverse area and surrounding environments located within the northeastern part of the San Francisco Volcanic Field (SFVF), north-central Arizona. To mimic an exploratory mission, we approached the region "blindly" by rejecting prior knowledge or preconceived notions of the regional geologic setting and focused instead only on image and topographic base maps that were intended to be equivalent to pre-cursor mission "orbital returns". We used photogeologic mapping techniques equivalent to those employed during the construction of modern planetary geologic maps. Based on image and topographic base maps, we identified 4 surficial units (talus, channel, dissected, and plains units), 5 volcanic units (older cone, younger cone, older flow, younger flow, and block field units), and 5 basement units (grey-toned mottled, red-toned platy, red-toned layered, light-toned slabby, and light-toned layered units). Comparison of our remote-based map units with published field-based map units indicates that the two techniques yield pervasively similar results of contrasting detail, with higher accuracies linked to remote-based units that have high topographic relief and tonal contrast relative to adjacent units. We list key scientific questions that remained after photogeologic mapping and prior to DRATS activities and identify 13 specific observations that the crew and science team would need to make in order to address those questions and refine the interpreted geologic context. We translated potential observations into 62 recommended sites for visitation and observation during the mission traverse. The production and use of a mission-specific photogeologic map for DRATS 2010 activities resulted in strategic and tactical recommendations regarding observational context and hypothesis tracking over the course of an exploratory mission.

  16. 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…

  17. 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...

  18. 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)

  19. 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

  20. 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.

  1. The Leelanau Benzie And Grand Traverse, Michigan Anomalies - Structural And Geobotanical Indicators Of Hydrocarbon Microseepage

    Science.gov (United States)

    Staskowski, Ronald J.

    1984-08-01

    Analysis of Landsat and Seasat imagery reveals several structural and geobotanical anomalies in the northwestern lower peninsula of Michigan. Integrating these surface anomalies with regional cross-sections and geophysical studies shows that they lie along predictable subsurface trends. These trends control hydrocarbon migration and accumulation; anomalies occur in both producing and untested portions of the trends. Subsequent to the acquisition and analysis of the satellite data, several "untested" areas have been drilled and successfully completed, suggesting that the anomalies are associated with hydrocarbon microseepage. The geobotanical and structural characteristics of Michigan are strongly affected by the last stage of Pleistocene glaciation. In moving through this portion of Michigan, the ice was deflected by a series of topographic features related to subsurface highs. This is indicated by the concave bends in the Port Huron and Manistee moraines, as well as the glacial lake terraces that formed along the edges of the northern topographic high as the ice retreated. The structural interpretation suggests that a large patch reef system may have existed in the northern portion of the study area during deposition of the Devonian Traverse Formation and the Silurian Niagara Group. The Traverse Formation underlies the Antrim Shale that outcrops below the glacial drift of the area. A large patch reef system would account for the differential movement of the ice since the associated limestones would be more resistant to erosion than the surrounding shales. In comparing the location of the geobotanical anomalies with the glacial deposits, an interesting interaction is revealed: over 75% of the anomalies are located in the more porous and permeable outwash deposits. Furthermore, every vegetation anomaly is associated with a lineament or lineament intersection on the structural interpretation. The geobotanical anomalies are also very transient. They appear only during

  2. Site selection and traverse planning to support a lunar polar rover mission: A case study at Haworth Crater

    Science.gov (United States)

    Heldmann, Jennifer L.; Colaprete, Anthony; Elphic, Richard C.; Bussey, Ben; McGovern, Andrew; Beyer, Ross; Lees, David; Deans, Matt

    2016-10-01

    Studies of lunar polar volatile deposits are of interest for scientific purposes to understand the nature and evolution of the volatiles, and also for exploration reasons as a possible in situ resource to enable long term human exploration and settlement of the Moon. Both theoretical and observational studies have suggested that significant quantities of volatiles exist in the polar regions, although the lateral and horizontal distribution remains unknown at the km scale and finer resolution. A lunar polar rover mission is required to further characterize the distribution, quantity, and character of lunar polar volatile deposits at these higher spatial resolutions. Here we present a case study for NASA's Resource Prospector (RP) mission concept for a lunar polar rover and utilize this mission architecture and associated constraints to evaluate whether a suitable landing site exists to support an RP flight mission. We evaluate the landing site criteria to characterize the Haworth Crater region in terms of expected hydrogen abundance, surface topography, and prevalence of shadowed regions, as well as solar illumination and direct to Earth communications as a function of time to develop a notional rover traverse plan that addresses both science and engineering requirements. We also present lessons-learned regarding lunar traverse path planning focusing on the critical nature of landing site selection, the influence of illumination patterns on traverse planning, the effects of performing shadowed rover operations, the influence of communications coverage on traverse plan development, and strategic planning to maximize rover lifetime and science at end of mission. Here we present a detailed traverse path scenario for a lunar polar volatiles rover mission and find that the particular site north of Haworth Crater studied here is suitable for further characterization of polar volatile deposits.

  3. 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.

  4. 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.

  5. African American Diaspora

    Directory of Open Access Journals (Sweden)

    Angela Brown

    2013-07-01

    Full Text Available The migration of blacks in North America through slavery became united.  The population of blacks past downs a tradition of artist through art to native born citizens. The art tradition involved telling stories to each generation in black families. The black culture elevated by tradition created hope to determine their personal freedom to escape from poverty of enslavement and to establish a way of life through tradition. A way of personal freedoms was through getting a good education that lead to a better foundation and a better way of life. With regard to all historic migrations (forced and voluntary, the African Union defined the African diaspora as "[consisting] of people of African origin living outside the continent, irrespective of their citizenship and nationality and who are willing to contribute to the development of the continent and the building of the African Union." Its constitutive act declares that it shall "invite and encourage the full participation of the African diaspora as an important part of our continent, in the building of the African Union." Keywords: literature concepts, African American abstracts

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. Foci of chronic circumscribed osteomyelitis (Brodie's abscess) that traverse the epiphyseal plate.

    Science.gov (United States)

    Bogoch, E; Thompson, G; Salter, R B

    1984-03-01

    We observed six children who presented with chronic circumscribed osteomyelitis involving the adjacent metaphysis and epiphysis of a long bone, communicating through and damaging the growth cartilage of the epiphyseal plate. Four of the six children were less than or equal to 10 years of age. All six patients presented with the mild symptoms and subtle clinical findings that are characteristic of "Brodie's abscess," which is usually confined to metaphyseal, or occasionally epiphyseal, bone. Four children were treated with antibiotics and by surgical evacuation of the abscess, with visualization of the defect in the epiphyseal plate. Two children were treated with antibiotics alone, initially by the intravenous route. At follow-up 2-14 years after treatment, all affected children had a normal result without evidence of growth disturbance. There are seven previously reported cases of chronic circumscribed osteomyelitis traversing the epiphyseal plate that resulted in growth disturbance. Based on our experience and that reported in the literature, we believe that the intravenous administration of appropriate antibiotics in high doses, followed by oral antibiotics, is sufficient treatment for some children presenting with this condition. The pathogenic organism is likely to be Staphylococcus aureus. Surgical evacuation of the lesion should be performed for acute osteomyelitis involving the epiphyseal plate, for sinus formation or drainage into a synovial joint, for failure of the patient to respond clinically to nonoperative therapy, and for confirmation of the diagnosis if doubt exists.

  14. 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.

  15. NUP-1 Is a large coiled-coil nucleoskeletal protein in trypanosomes with lamin-like functions.

    Directory of Open Access Journals (Sweden)

    Kelly N DuBois

    Full Text Available A unifying feature of eukaryotic nuclear organization is genome segregation into transcriptionally active euchromatin and transcriptionally repressed heterochromatin. In metazoa, lamin proteins preserve nuclear integrity and higher order heterochromatin organization at the nuclear periphery, but no non-metazoan lamin orthologues have been identified, despite the likely presence of nucleoskeletal elements in many lineages. This suggests a metazoan-specific origin for lamins, and therefore that distinct protein elements must compose the nucleoskeleton in other lineages. The trypanosomatids are highly divergent organisms and possess well-documented but remarkably distinct mechanisms for control of gene expression, including polycistronic transcription and trans-splicing. NUP-1 is a large protein localizing to the nuclear periphery of Trypanosoma brucei and a candidate nucleoskeletal component. We sought to determine if NUP-1 mediates heterochromatin organization and gene regulation at the nuclear periphery by examining the influence of NUP-1 knockdown on morphology, chromatin positioning, and transcription. We demonstrate that NUP-1 is essential and part of a stable network at the inner face of the trypanosome nuclear envelope, since knockdown cells have abnormally shaped nuclei with compromised structural integrity. NUP-1 knockdown also disrupts organization of nuclear pore complexes and chromosomes. Most significantly, we find that NUP-1 is required to maintain the silenced state of developmentally regulated genes at the nuclear periphery; NUP-1 knockdown results in highly specific mis-regulation of telomere-proximal silenced variant surface glycoprotein (VSG expression sites and procyclin loci, indicating a disruption to normal chromatin organization essential to life-cycle progression. Further, NUP-1 depletion leads to increased VSG switching and therefore appears to have a role in control of antigenic variation. Thus, analogous to vertebrate

  16. 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...

  17. 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...

  18. 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...

  19. Pesticide concentrations in wetlands on the Lake Traverse Indian Reservation, South and North Dakota, July 2015

    Science.gov (United States)

    Carter, Janet M.; Thompson, Ryan F.

    2016-05-04

    During July 2015, water samples were collected from 18 wetlands on the Lake Traverse Indian Reservation in northeastern South Dakota and southeastern North Dakota and analyzed for physical properties and 54 pesticides. This study by the U.S. Geological Survey in cooperation with the Sisseton-Wahpeton Oyate was designed to provide an update on pesticide concentrations of the same 18 wetlands that were sampled for a reconnaissance-level assessment during July 2006. The purpose of this report is to present the results of the assessment of pesticide concentrations in selected Lake Traverse Indian Reservation wetlands during July 2015 and provide a comparison of pesticide concentrations between 2006 and 2015.Of the 54 pesticides that were analyzed for in the samples collected during July 2015, 47 pesticides were not detected in any samples. Seven pesticides—2-chloro-4-isopropylamino-6-amino-s-triazine (CIAT); 2,4–D; acetachlor; atrazine; glyphosate; metolachlor; and prometon—were detected in the 2015 samples with estimated concentrations or concentrations greater than the laboratory reporting level, and most pesticides were detected at low concentrations in only a few samples. Samples from all wetlands contained at least one detected pesticide. The maximum number of pesticides detected in a wetland sample was six, and the median number of pesticides detected was three.The most commonly detected pesticides in the 2015 samples were atrazine and the atrazine degradate CIAT (also known as deethylatrazine), which were detected in 14 and 13 of the wetlands sampled, respectively. Glyphosate was detected in samples from 11 wetlands, and metolachlor was detected in samples from 10 wetlands. The other detected pesticides were 2,4–D (4 wetlands), acetochlor (3 wetlands), and prometon (1 wetland).The same pesticides that were detected in the 2006 samples were detected in the 2015 samples, with the exception of simazine, which was detected only in one sample in 2006

  20. 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.

  1. Coordination variation of hydrated Cu2+/Br1- ions traversing the interfacial water in mesopores

    Science.gov (United States)

    Wang, Q.; Huang, X. F.; Li, C. X.; Pan, L. Q.; Wu, Z. H.; Hu, T. D.; Jiang, Z.; Huang, Y. Y.; Cao, Z. X.; Sun, G.; Lu, K. Q.

    2012-06-01

    Resolution of the atomistic and electronic details about the coordination structure variation of hydrated ions in the interfacial water is still a tough challenge, which is, however, essentially important for the understanding of ion adsorption, permeation and other similar processes in aqueous solutions. Here we report the tracing of coordination structure variation for hydrated Cu2+/Br1- ions traversing the interfacial water in Vycor mesopores (ϕ = 7.6 nm) by employing both X-ray absorption near edge structure and extended X-ray absorption fine structure spectroscopies. By controlled desorption/adsorption of water, the filling fraction of the mesopores, thus the water layer thickness, can be adjusted, which in turn effects the variation of coordination structure of the ions therein. It is found that both Cu2+ and Br1- ions prefer staying exclusively in the core water, and in this circumstance no ion pairs have been detected in the solution of concentrations up to 1.0 M. Following capillary decondensation occurring at a filling fraction of ˜35% which corresponds to a water layer of about three monolayers, Br1- ions begin immediately to reconstruct their first coordination shell, characterized by ionic dehydration, shrinkage of ion-water bond length, and formation of ion pairs. In contrast, Cu2+ ions can retain a bulk-like coordination structure till being driven to bond directly to the pore surface when the filling fraction is below 20%. At the final stage of dehydration via thermal vacuum treatment at 110°C, Cu2+ ions can be completely reduced to the Cu1+ state, and recover at room temperature only when the filling fraction is above 14%. These results may be inspirable for the investigation of similar problems concerning hydrated ions in water solution under different confining conditions.

  2. Coordination variation of hydrated Cu2+/Br1− ions traversing the interfacial water in mesopores

    Directory of Open Access Journals (Sweden)

    Q. Wang

    2012-06-01

    Full Text Available Resolution of the atomistic and electronic details about the coordination structure variation of hydrated ions in the interfacial water is still a tough challenge, which is, however, essentially important for the understanding of ion adsorption, permeation and other similar processes in aqueous solutions. Here we report the tracing of coordination structure variation for hydrated Cu2+/Br1- ions traversing the interfacial water in Vycor mesopores (ϕ = 7.6 nm by employing both X-ray absorption near edge structure and extended X-ray absorption fine structure spectroscopies. By controlled desorption/adsorption of water, the filling fraction of the mesopores, thus the water layer thickness, can be adjusted, which in turn effects the variation of coordination structure of the ions therein. It is found that both Cu2+ and Br1- ions prefer staying exclusively in the core water, and in this circumstance no ion pairs have been detected in the solution of concentrations up to 1.0 M. Following capillary decondensation occurring at a filling fraction of ∼35% which corresponds to a water layer of about three monolayers, Br1- ions begin immediately to reconstruct their first coordination shell, characterized by ionic dehydration, shrinkage of ion-water bond length, and formation of ion pairs. In contrast, Cu2+ ions can retain a bulk-like coordination structure till being driven to bond directly to the pore surface when the filling fraction is below 20%. At the final stage of dehydration via thermal vacuum treatment at 110°C, Cu2+ ions can be completely reduced to the Cu1+ state, and recover at room temperature only when the filling fraction is above 14%. These results may be inspirable for the investigation of similar problems concerning hydrated ions in water solution under different confining conditions.

  3. Estimativas da qualidade de linhas poligonais topográficas Quality estimations of topographical traverses

    Directory of Open Access Journals (Sweden)

    Mário Stringhini

    2008-09-01

    Full Text Available O objetivo deste artigo é descrever um procedimento que contribui com estimativas de qualidade de levantamento topográficos mediante a pré-análise e estimativas obtidas a partir de análise pós-ajustamento. As estimativas são dadas pelo teste qui-quadrado da forma quadrática do erro de fechamento, pelo teste qui-quadrado da forma quadrática dos resíduos obtidos no ajustamento pelo método dos mínimos quadrados, pelo teste data snooping de Baarda, pela elipse dos erros, pela elipse de confiança, pelo círculo do erro de posição e pelo círculo do erro médio. Estes conceitos são examinados por meio de valores numéricos no caso de uma linha poligonal simples implantada no campus da Universidade Federal de Santa Maria e medida com um taquímetro eletrônico.The objective through this article is to describe a procedure that contributes with quality survey estimations by means pre-analysis survey and estimations by means post-adjustment. The estimations are given by the chi-square test of the quadratic form of misclosures, the chi-square of the quadratic form of residuals from the least-squares adjustment method, the Baarda's data snooping test, the standard ellipse, the confidence ellipse, position error circle and mean error circle. These concepts are examined through the numerical values provided in the case of a simple topographical traverse which was implanted at the Universidade Federal de Santa Maria Campus with electronic tachymeter.

  4. 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.

  5. 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.

  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. 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...

  8. Variation in polarization of high-energy $\\gamma$-quanta traversing a bunch of polarized laser photons

    CERN Document Server

    Kotkin, G L

    1996-01-01

    The elastic light-light scattering below the threshold of the $e^+e^-$ pair production leads to a variation in polarization of hard $\\gamma$-quanta traversing without loss a region where the laser light is focused. Equations are obtained which determine the variation of Stokes parameters of that this effect can be observed in the experiment E-144 at SLAC. It should be taken into account (and, perhaps, it can be used) in experiments at future

  9. GPS-derived horizontal ice flow velocities along the traverse route from Zhongshan Station to Dome-A, East Antarctica

    Institute of Scientific and Technical Information of China (English)

    王清华

    2003-01-01

    The traverse route from Zhongshan Station to Dome-A is one of the most important expedition routes of ITASE Project.China carried out 3 inland traverses during the 1996/1997, 1997/1998, 1998/1999 austral summer field seasons.The field team reached inland 300 km, 500 km and 1100 km away from Zhongshan Station respectively.Some ice motion stakes were set up, occupied and reoccupied along the route by GPS technology.It showed that the ice along the traverse route flowed with an 8-25 ma-1 velocity to the northwest, the direction of the bottom of Lambert Glacier Basin.They coincide with the results along the eastern section from LGB59-70 of the LGB route deduced by Australia in both values and directions.Furthermore, the directions of the horizontal flow are perpendicular to the surface topography contour.The much larger velocity at the point of LT980 with an approximate value of 100 ma-1 was probed.It was caused by a 15 km wide trough on the bed beneath this point.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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 ...

  16. 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...

  17. 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

  18. 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…

  19. The trypanosome Rab-related proteins RabX1 and RabX2 play no role in intracellular trafficking but may be involved in fly infectivity.

    Directory of Open Access Journals (Sweden)

    Senthil Kumar A Natesan

    Full Text Available BACKGROUND: Rab GTPases constitute the largest subgroup of the Ras superfamily and are primarily involved in vesicle targeting. The full extent of Rab family function is unexplored. Several divergent Rab-like proteins are known but few have been characterized. In Trypanosoma brucei there are sixteen Rab genes, but RabX1, RabX2 and RabX3 are divergent within canonical sequence regions. Where known, trypanosome Rab functions are broadly conserved when orthologous relationships may be robustly established, but specific functions for RabX1, X2 and X3 have yet to be determined. RabX1 and RabX2 originated via tandem duplication and subcellular localization places RabX1 at the endoplasmic reticulum, while RabX2 is at the Golgi complex, suggesting distinct functions. We wished to determine whether RabX1 and RabX2 are involved in vesicle transport or other cellular processes. METHODOLOGY/PRINCIPAL FINDINGS: Using comparative genomics we find that RabX1 and RabX2 are restricted to trypanosomatids. Gene knockout indicates that RabX1 and RabX2 are non-essential. Simultaneous RNAi knockdown of both RabX1 and RabX2, while partial, was also non-lethal and may suggest non-redundant function, consistent with the distinct locations of the proteins. Analysis of the knockout cell lines unexpectedly failed to uncover a defect in exocytosis, endocytosis or in the morphology or location of multiple markers for the endomembrane system, suggesting that neither RabX1 nor RabX2 has a major role in intracellular transport. However, it was apparent that RabX1 and RabX2 knockout cells displayed somewhat enhanced survival within flies. CONCLUSIONS/SIGNIFICANCE: RabX1 and RabX2, two members of the trypanosome Rab subfamily, were shown to have no major detectable role in intracellular transport, despite the localization of each gene product to highly specific endomembrane compartments. These data extend the functional scope of Rab proteins in trypanosomes to include non

  20. 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

  1. 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

  2. 基于二叉树的反向Hash链遍历%Reverse Hash Chain Traversal Based on Binary Tree

    Institute of Scientific and Technical Information of China (English)

    傅建庆; 吴春明; 吴吉义; 平玲娣

    2012-01-01

    提出了一种反向Hash链遍历的时间、空间复杂度优化算法.采用堆栈操作实现了高效的反向Hash链遍历,并将Hash链遍历过程映射到了二叉树的后序遍历过程,利用二叉树性质对存储和计算性能进行了理论化分析和证明.分析证明结果表明,遍历对长为n的反向Hash链时,算法只需要存储「1bn」+1个节点值,并且进行不多于((「) 1b n」/2+1)n次Hash计算次数.相比同类其他算法,该算法并不要求链长为2的整数次方.通过对算法进行基于k叉树(k≥3)的扩展,进一步将存储空间降低到(「)logk[(k-1)n+1]」,但总计算次数提高到[(「)log[(k-1)n+1]」-1)k/2+1]n;通过在算法执行前先把Hash链平分为p段(P≥2),将总计算次数降低到([1b(n/p)]/2+1)n,但是所需的存储空间提高到([1b(n/p)]+1)p.%An algorithm improving the time and space complexity of reverse Hash chain traversal is proposed. By mapping the traversal of a reverse Hash chain to the postorder traversal of a binary tree, the proposed algorithm reduces the product of the total times of Hash operations and the storage space required to O(n(lb n)2), where n is the length of the reverse Hash chain. Analysis and proof using the property of the binary tree show that the proposed algorithm requires to save only [lbn] + l nodesat the same time, and needs no more than ([lb nj /2 + l)w times of Hash operations totally. Comparedwith other algorithms, the proposed one can be applied to Hash chains with any length, eliminating the limitation that the length of chain must be of 2 integer-th power. Then an advanced algorithm is proposed by mapping the traversal of a reverse Hash chain to the postorder traversal of a k-ary tree,where k is an integer no less than 3, and the space required is reduced to | logj[(jfe - Dn + l]|, but thetimes of Hash operations required is raised to [( | logk[(k- l)n + 1] | -l)k/2 + l]n. Finally, another advanced algorithm is proposed by splitting Hash chain

  3. 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.

  4. 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-

  5. 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

  6. 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....

  7. 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...

  8. 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....

  9. 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: ...

  10. 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.

  11. 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)

  12. 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.

  13. 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

  14. Protein: CAD [Trypanosomes Database

    Lifescience Database Archive (English)

    Full Text Available CAD carbamoyl-phosphate synthetase 2, aspartate transcarbamylase, and dihydroorotaseCA...D trifunctional proteincarbamoylphosphate synthetase 2/aspartate transcarbamylase/dihydroorotasemultifunctional protein CA...D H.sapiens 47458828 18105007 790 P27708 CAD_(gene) 2.1.3.2|3.5.2.3|6.3.5.5 114010 2p22-p21 hsa00250|hsa00240 ...

  15. Ablation of succinate production from glucose metabolism in the procyclic trypanosomes induces metabolic switches to the glycerol 3-phosphate/dihydroxyacetone phosphate shuttle and to proline metabolism.

    Science.gov (United States)

    Ebikeme, Charles; Hubert, Jane; Biran, Marc; Gouspillou, Gilles; Morand, Pauline; Plazolles, Nicolas; Guegan, Fabien; Diolez, Philippe; Franconi, Jean-Michel; Portais, Jean-Charles; Bringaud, Frédéric

    2010-10-15

    Trypanosoma brucei is a parasitic protist that undergoes a complex life cycle during transmission from its mammalian host (bloodstream forms) to the midgut of its insect vector (procyclic form). In both parasitic forms, most glycolytic steps take place within specialized peroxisomes, called glycosomes. Here, we studied metabolic adaptations in procyclic trypanosome mutants affected in their maintenance of the glycosomal redox balance. T. brucei can theoretically use three strategies to maintain the glycosomal NAD(+)/NADH balance as follows: (i) the glycosomal succinic fermentation branch; (ii) the glycerol 3-phosphate (Gly-3-P)/dihydroxyacetone phosphate (DHAP) shuttle that transfers reducing equivalents to the mitochondrion; and (iii) the glycosomal glycerol production pathway. We showed a hierarchy in the use of these glycosomal NADH-consuming pathways by determining metabolic perturbations and adaptations in single and double mutant cell lines using a combination of NMR, ion chromatography-MS/MS, and HPLC approaches. Although functional, the Gly-3-P/DHAP shuttle is primarily used when the preferred succinate fermentation pathway is abolished in the Δpepck knock-out mutant cell line. In the absence of these two pathways (Δpepck/(RNAi)FAD-GPDH.i mutant), glycerol production is used but with a 16-fold reduced glycolytic flux. In addition, the Δpepck mutant cell line shows a 3.3-fold reduced glycolytic flux compensated by an increase of proline metabolism. The inability of the Δpepck mutant to maintain a high glycolytic flux demonstrates that the Gly-3-P/DHAP shuttle is not adapted to the procyclic trypanosome context. In contrast, this shuttle was shown earlier to be the only way used by the bloodstream forms of T. brucei to sustain their high glycolytic flux.

  16. 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.

  17. The response of trypanosomes and other eukaryotes to ER stress and the spliced leader RNA silencing (SLS) pathway in Trypanosoma brucei.

    Science.gov (United States)

    Michaeli, Shulamit

    2015-01-01

    The unfolded protein response (UPR) is induced when the quality control machinery of the cell is overloaded with unfolded proteins or when one of the functions of the endoplasmic reticulum (ER) is perturbed. Here, I describe UPR in yeast and mammals, and compare it to what we know about pathogenic fungi and the parasitic protozoans from the order kinetoplastida, focusing on the novel pathway the spliced leader silencing (SLS) in Trypanosoma brucei. Trypanosomes lack conventional transcription regulation, and thus, lack most of the UPR machinery present in other eukaryotes. Trypanosome genes are transcribed in polycistronic units that are processed by trans-splicing and polyadenylation. In trans-splicing, which is essential for processing of each mRNA, an exon known as the spliced leader (SL) is added to all mRNAs from a small RNA, the SL RNA. Under severe ER stress, T. brucei elicits the SLS pathway. In SLS, the transcription of the SL RNA gene is extinguished, and the entire transcription complex dissociates from the SL RNA promoter. Induction of SLS is mediated by an ER-associated kinase (PK3) that migrates to the nucleus, where it phosphorylates the TATA-binding protein (TRF4), leading shut-off of SL RNA transcription. As a result, trans-splicing is inhibited and the parasites activate a programmed cell death (PCD) pathway. Despite the ability to sense the ER stress, the different eukaryotes, especially unicellular parasites and pathogenic fungi, developed a variety of unique and different ways to sense and adjust to this stress in a manner different from their host.

  18. 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

  19. 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.

  20. Reduced integrity of sensorimotor projections traversing the posterior limb of the internal capsule in children with congenital hemiparesis.

    Science.gov (United States)

    Tsao, Henry; Pannek, Kerstin; Fiori, Simona; Boyd, Roslyn N; Rose, Stephen

    2014-02-01

    There is reduced integrity of corticospinal projections that traverse the posterior limb of the internal capsule (PLIC) in children with unilateral cerebral palsy (CP). It remains unclear whether there are changes in integrity of other projections traversing the PLIC. Forty children with congenital hemiparesis and 15 typically developing children underwent structural and diffusion-weighted MRI. All children with congenital hemiparesis showed lesions to the periventricular white matter. Structural images were parcellated into 34 cortical regions per hemisphere and posterior limb of the internal capsule was identified. PLIC connections to each cortical region were extracted using probabilistic tractography. Differences between hemispheres for each cortical projection (asymmetry index (AI)) and tract microstructure (fractional anisotropy (FA), mean diffusivity (MD)) were assessed. The results showed that 17 children (42.5%) with congenital hemiparesis showed bilateral lesions on structural MRI. Projections to the primary motor cortex (precentral gyrus and paracentral lobule) showed greater asymmetry in unilateral CP group compared to typically developing children and indicate reduced projections on the hemisphere contralateral to the impaired limb (i.e., contralateral hemisphere). Reduced FA and increased MD were also observed for connections with the primary motor cortex, primary sensory cortex (postcentral gyrus) and precuneus on the contralateral hemisphere in children with congenital hemiparesis. Similar changes were observed between children with unilateral and bilateral lesions on structural MRI. Notably, microstructural changes were associated with deficits in both sensory and motor function. The findings further unravel the underlying neuroanatomical correlates of sensorimotor deficits in children with congenital hemiparesis. PMID:24291822

  1. 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.

  2. Settlement Impact Analysis and Countermeasure Research of the Down Traversing Formed by the Double-Arch Subway Tunnels through the Existing Railways in Loess Area

    Directory of Open Access Journals (Sweden)

    Wang Lixin

    2015-01-01

    Full Text Available With the large-scale construction of city subways, the down traversing formed by subway running tunnels through the existing railways or railway yards are increasing day by day. Down traversing in shield method becomes common; however, the engineering cases which can be referable in the down traversing formed by the shallow-buried excavation of double-arch tunnels through the existing railways are very little. The ability to effectively control the excavation of shallow-buried subway tunnels can directly affect the safety of railway operation. According to the engineering characteristics of the down traversing formed by the shallow-buried excavation of double-arch tunnels in loessial layer, this paper proposed the standards for railway bed and track settlement control, and offers underground water treatment measures with assistant steps implemented on the ground surface during construction, so as to ensure the railway operation safety during the construction of the tunnel. Moreover, this paper applied MIDAS-GTS finite element software to make numerical simulation analysis of the down traversing formed by the double-arch tunnel through the railway and obtained the deformation laws during down traversing. The calculations suggest the railway track deformation caused by the down traversing construction of the double-arch tunnel in this project can meet related control standard requirements. There’s certain reference value contained in the deformation laws for the point locations of monitoring measurement. The research conclusions can provide scientific proof and technical guidance for the design and construction of this running tunnel project in order to offer reference for similar projects in the future.

  3. 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

  4. 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

  5. Diversity among African pygmies.

    Science.gov (United States)

    Ramírez Rozzi, Fernando V; Sardi, Marina L

    2010-01-01

    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.

  6. 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.

  7. 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.

  8. 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...

  9. 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 ...

  10. 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...

  11. 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.

  12. 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.

  13. 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....

  14. 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.

  15. 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

  16. 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.

  17. 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...

  18. 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

  19. Understanding the Rise of African Business

    DEFF Research Database (Denmark)

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

    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 African firm strategy and performance that takes into account the specificities of the African business environment and African firm capabilities. The paper starts by juxtaposing the widespread pessimistic view of African business with more recent, optimistic studies on African firms’ performance....... The 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...

  20. 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.

  1. 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.

  2. 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.

  3. 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…

  4. 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.

  5. 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

  6. 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...... that donor aid has come to be in Africa." He provides a historic and contemporary context for the unification of monetary and customs systems across Africa and argues for a dual currency system for the self-financing of African development and for sustained self-determination....

  7. 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...

  8. Surfaces on African sculpture

    Directory of Open Access Journals (Sweden)

    John Mack

    2011-12-01

    Full Text Available Review of: Leonard Kahan, Donna Page, and Pascal James Imperato (eds in collaboration with Charles Bordogna and Bolaji Campbell with an introduction by Patrick McNaughton, Surfaces: Color, Substances, and Ritual Applications on African Sculpture, Indiana University Press, 2009.The book reviewed here has potential interest to a wide range of readers, whether researchers and academics, museum, curators, conservators or connoisseurs. It examines the perception of surface as an aspect of the indigenous understanding of sculpted objects in sub-Saharan Africa, treating of questions of materials, patination, colouration and use. It includes both survey essays and case studies (on the Bamana of Mali and the Yoriuba of Nigeria in a compendium which has suggestive implications beyond the immediate field of the Africanists to whom it is principally addressed.

  9. West African Antislavery Movements

    DEFF Research Database (Denmark)

    Hahonou, Eric Komlavi; Pelckmans, Lotte

    2011-01-01

    to unite, mobilize and struggle. Members of anti-slavery movements with slave origins accessed power positions through peaceful electoral processes in Benin, mali, Niger and Mauritania. People of slave origins gained ground in local politics of a number of municipalities. In localities where anti-slavery......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 penal code of Mali. Anti-slavery activists not only address their claims to their national governments but also intend to initiate change at local level. In that respect the democratic decentralization reforms were significant because they allowed educated anti-slavery activists to appeal their brethren...

  10. 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.

  11. 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

  12. 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.

  13. 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.

  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. 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...

  16. 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.

  17. 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.

  18. Human Behavior in the Epidemiology and Control of African Trypanosomosis in Kachia Local Government Area of Kaduna State, Nigeria

    Directory of Open Access Journals (Sweden)

    S.M. Samdi

    2012-10-01

    Full Text Available The aim of this study was to investigate the prevalence of trypanosomosis in white Fulani cattle in Ladduga District, Kachia LGA of Kaduna State and further highlight the importance of human behavior, belief, attitude and activity in the epidemiology and control of African trypanosomosis. A total of 65 animals were sampled randomly. Blood collected from the jugular vein was stored in heparinized blood containers. The standard trypanosomosis diagnostic method was employed. An overall infection rate of 29.2% was recorded in the herd with bulls accounting for 20.0% and cows 32.0%. The average Packed Cell Volume (PCV of infected animals (23.6±0.4% was lower than non-infected (36.4±0.7%. These values were statistically significant (p<0.05. Clinical signs observed were lacrimation, pale mucus membrane, rough hair coat and presence of ticks. However, despite good appetite and availability of forage, emaciation was observed in 29 animals (45.0%. The trypanosomes encountered were T. vivax (42.0%, T. congolense (15.7%, T. brucei (21.0% and mixed infection (21.0%. Traps caught only biting flies; Tabanus and Stomoxy species.

  19. Cyclin-Dependent Kinase CRK9, Required for Spliced Leader trans Splicing of Pre-mRNA in Trypanosomes, Functions in a Complex with a New L-Type Cyclin and a Kinetoplastid-Specific Protein.

    Science.gov (United States)

    Badjatia, Nitika; Park, Sung Hee; Ambrósio, Daniela L; Kirkham, Justin K; Günzl, Arthur

    2016-03-01

    In eukaryotes, cyclin-dependent kinases (CDKs) control the cell cycle and critical steps in gene expression. The lethal parasite Trypanosoma brucei, member of the phylogenetic order Kinetoplastida, possesses eleven CDKs which, due to high sequence divergence, were generically termed CDC2-related kinases (CRKs). While several CRKs have been implied in the cell cycle, CRK9 was the first trypanosome CDK shown to control the unusual mode of gene expression found in kinetoplastids. In these organisms, protein-coding genes are arranged in tandem arrays which are transcribed polycistronically. Individual mRNAs are processed from precursor RNA by spliced leader (SL) trans splicing and polyadenylation. CRK9 ablation was lethal in cultured trypanosomes, causing a block of trans splicing before the first transesterification step. Additionally, CRK9 silencing led to dephosphorylation of RNA polymerase II and to hypomethylation of the SL cap structure. Here, we tandem affinity-purified CRK9 and, among potential CRK9 substrates and modifying enzymes, discovered an unusual tripartite complex comprising CRK9, a new L-type cyclin (CYC12) and a protein, termed CRK9-associated protein (CRK9AP), that is only conserved among kinetoplastids. Silencing of either CYC12 or CRK9AP reproduced the effects of depleting CRK9, identifying these proteins as functional partners of CRK9 in vivo. While mammalian cyclin L binds to CDK11, the CRK9 complex deviates substantially from that of CDK11, requiring CRK9AP for efficient CRK9 complex formation and autophosphorylation in vitro. Interference with this unusual CDK rescued mice from lethal trypanosome infections, validating CRK9 as a potential chemotherapeutic target.

  20. 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...

  1. 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

  2. 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...

  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. The New African Civil-Military Relations

    DEFF Research Database (Denmark)

    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 Lesotho...... 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 Institute (APPRI...

  5. 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.

  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. 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

  8. An African ethic for nursing?

    Science.gov (United States)

    Haegert, S

    2000-11-01

    This article derives from a doctoral thesis in which a particular discourse was used as a 'paradigm case'. From this discourse an ethic set within a South African culture arose. Using many cultural 'voices' to aid the understanding of this narrative, the ethic shows that one can build on both a 'justice' and a 'care' ethic. With further development based on African culture one can take the ethic of care deeper and reveal 'layers of understanding'. Care, together with compassion, forms the foundation of morality. Nursing ethics has followed particular western moral philosophers. Often nursing ethics has been taught along the lines of Kohlberg's theory of morality, with its emphasis on rules, rights, duties and general obligations. These principles were universalistic, masculine and noncontextual. However, there is a new ethical movement among Thomist philosophers along the lines to be expounded in this article. Nurses such as Benner, Bevis, Dunlop, Fry and Gadow--to name but a few--have welcomed the concept of an 'ethic of care'. Gilligan's work gave a feminist view and situated ethics in the everyday aspects of responsiveness, responsibility, context and concern. Shutte's search for a 'philosophy for Africa' has resulted in finding similarities in Setiloane and in Senghor with those of Thomist philosophers. Using this African philosophy and a research participant's narrative, an African ethic evolves out of the African proverb: 'A person is a person through other persons', or its alternative rendering: 'I am because we are: we are because I am.' This hermeneutic narrative reveals 'the way affect imbues activity with ethical meaning' within the context of a black nursing sister in a rural South African hospital. It expands upon the above proverb and incorporates the South African constitutional idea of 'Ubuntu' (compassion and justice or humanness).

  9. Cinderella Complex of Traversing Drama%穿越剧中的“灰姑娘”情结

    Institute of Scientific and Technical Information of China (English)

    陈国钦; 文丽

    2014-01-01

    以女性为主要受众群体的穿越剧多采用灰姑娘的叙事模式。以“穿越”为契机,穿越版的灰姑娘形象揭示了现代女性自我表达、自我实现的深层心理诉求。“多马王子”现象则反映了现代女性在消费文化背景下的情感需求,而她们对待情敌和敌人的态度更是女性独立、自信的体现。在女性视角下,灰姑娘们张扬个性、表达自我,在消费文化的大潮中成为女性观众的偶像。%The traversing drama with female as the main audience almost use Cinderella.Through “traversing”as an op-portunity,the image of Cinderella version reveals the deep psychological demands of modern women’s self expression and self realization.“Multiple Prince”phenomenon is the reflection of modern women’s emotional needs in the context of consumer culture,and their attitude of treating rival and enemy is the embodiment of female independence and self-confi-dence.In female perspective,Cinderella has personality and self expression,becoming the idols of female audience in the tide of consumer culture.

  10. 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.

  11. 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.

  12. 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

    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 .%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。

  13. 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

    2016-09-01

    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.

  14. 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.

  15. African horse sickness.

    Science.gov (United States)

    Mellor, Philip Scott; Hamblin, Christopher

    2004-01-01

    African horse sickness virus (AHSV) causes a non-contagious, infectious insect-borne disease of equids and is endemic in many areas of sub-Saharan Africa and possibly Yemen in the Arabian Peninsula. However, periodically the virus makes excursions beyond its endemic areas and has at times extended as far as India and Pakistan in the east and Spain and Portugal in the west. The vectors are certain species of Culicoides biting midge the most important of which is the Afro-Asiatic species C. imicola. This paper describes the effects that AHSV has on its equid hosts, aspects of its epidemiology, and present and future prospects for control. The distribution of AHSV seems to be governed by a number of factors including the efficiency of control measures, the presence or absence of a long term vertebrate reservoir and, most importantly, the prevalence and seasonal incidence of the major vector which is controlled by climate. However, with the advent of climate-change the major vector, C. imicola, has now significantly extended its range northwards to include much of Portugal, Spain, Italy and Greece and has even been recorded from southern Switzerland. Furthermore, in many of these new locations the insect is present and active throughout the entire year. With the related bluetongue virus, which utilises the same vector species of Culicoides this has, since 1998, precipitated the worst outbreaks of bluetongue disease ever recorded with the virus extending further north in Europe than ever before and apparently becoming endemic in that continent. The prospects for similar changes in the epidemiology and distribution of AHSV are discussed.

  16. 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...

  17. 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...

  18. Main: MPA5 [TP Atlas

    Lifescience Database Archive (English)

    Full Text Available University of Tokyo - Trypanosomiases are diseases caused by parasitic protozoan trypanosomes - A half million people...rasitic protozoan trypanosomes. A half million people suffer from African trypano

  19. African American Teaching and the Matriarchal Performance.

    Science.gov (United States)

    Jeffries, Rhonda Baynes

    This paper discusses the role of matriarchs in African-American culture, explaining that traditionally, African-American matriarchs arise from a combination of African norms and American social positions that naturally forces them to assume leadership conditions. The roles these women assume are a response to the desire to survive in a society…

  20. African pastoralist systems: An integrated approach

    OpenAIRE

    Fratkin, E.; Galvin, K.A.; Roth, E.A.

    1994-01-01

    Metadata only record The chapters in this book cover the following topics: Archaeological Perspectives on East African Pastoralism; Pastoralism in Historic Perspective; Mobility and Land Use Among African Pastoralists: Old Conceptual Problems and New Interpretations; Labor, Livestock, and Land: The Organization of Pastoral Production; Diet, Nutrition, and Pastoral Strategy; Demographic Systems: Two East African Examples; Child Fostering Among Nomadic Turkana Pastoralists: Demographic and H...

  1. The African American Image in American Cinema.

    Science.gov (United States)

    Bourne, St. Clair

    1990-01-01

    Political conditions have influenced the screen images of U.S. cinema, and the images of African Americans have reflected prevailing social stereotypes. The history of African-American representation in films is traced, and it is noted that the tendency to portray African Americans stereotypically has not changed. (SLD)

  2. 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

  3. African Centered Knowledge: A British Perspective.

    Science.gov (United States)

    Christian, Mark

    2001-01-01

    Considers the impact of African centered knowledge within the United Kingdom. Recent development of African Diaspora studies has forged links between various black Atlantic communities. The United Kingdom has experienced positive grassroots community response to the work of noted African centered scholars, yet within the British academy,…

  4. 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

  5. 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

  6. 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

  7. Major-Element Compositional Diversity Observed by ChemCam Along the MSL Traverse: The First Three Years

    Science.gov (United States)

    Wiens, R. C.; Mangold, N.; Maurice, S.; Blaney, D. L.; Clegg, S. M.; Gasda, P. J.; Frydenvang, J.; Gasnault, O.; Forni, O.; Cousin, A.; Lasue, J.; Lanza, N.; Anderson, R. B.; Sautter, V.; Bridges, J.; Le Deit, L.; Nachon, M.; Rapin, W.; Meslin, P. Y.; Newsom, H. E.; Clark, B. C.; Vaniman, D. T.; Bridges, N.; Herkenhoff, K. E.; Ehlmann, B. L.; Dyar, M. D.; Fisk, M. R.; Francis, R.; Leveille, R. J.; Johnson, J. R.; Melikechi, N.; Jackson, R.; Fabre, C.; Payré, V.; Grotzinger, J. P.; Vasavada, A. R.; Crisp, J. A.

    2015-12-01

    ChemCam on Curiosity has used LIBS to obtain elemental compositions of >6000 target points at distances to 7.4 m from the rover. Observations include igneous clasts, sediments, diagenetic features, and other details often not accessible by the rover arm. A major re-calibration was recently completed using >350 standards. This significantly improved the accuracies of mineral end-members including plag-feldspars, hi-Si compositions, oxide grains, Mg-rich end-members (presumably Mg saponites; not yet confirmed by CheMin), and Mg and Ca sulfates. Here we draw conclusions from the overall compositional distributions observed in Gale crater from landing until the present using the new calibration. Observations from Bradbury Rise (sols 0-53, 326-520) show a scattering of compositions toward mineral end-members from igneous clasts and pebbles transported from the crater rim. In contrast, Sheepbed mudstones (first drill location; sols 126-300) form a tight cluster close to average Mars composition. The nearby Shaler fluvial sandstone outcrop (sols 306-325)--the first outcrop of potential deltaic foreset beds--shows K enrichment. This enrichment reaches a peak of 6 wt % K2O (sol 625) in the Mt. Remarkable member of the Kimberley formation, Kimberley being a drill location flanked by foreset beds 7 km SW of Shaler. The Pahrump outcrop (sols 753-919)—first observed material of the Murray formation at Mt. Sharp's base—shows lower Mg, higher Si, and much higher Al, consistent with stronger alteration. Further along the traverse ChemCam discovered an outcrop of light-toned Murray formation rock (sols 992 on) of nearly pure SiO2+TiO2. Overall, the ChemCam database points to a very strong diversity of inputs and alteration processes within a relatively short distance within Gale. Igneous compositions: while Jake Matijevic, a float analyzed early by APXS, appeared nepheline normative, no clear nepheline has been found by ChemCam. Additionally, despite the significant number of

  8. 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.

  9. 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...

  10. Origins, consolidation and challenges of African Hispanism

    Directory of Open Access Journals (Sweden)

    Vital Tama Bena

    2014-08-01

    Full Text Available The African continent today takes into consideration a cultural movement which can be called African Hispanism. Born with the beginning of the post-colonial era, this African Hispanism has witnessed a progressive setting up in African countries thanks to the impetus of teachers of the Spanish language. Today that action benefits from a notorious cultural life as observed trough Spanish users of that language on the one hand; on the other hand the birth of a very promising African Spanish literature. Yet some future challenges are to come for a real fruitful future of that cultural movement. Key words: Spanish language; Africa intercultural exchanges.

  11. Landscapes of Aspiration in Guangzhou’s African Music Scene: Beyond the Trading Narrative

    Directory of Open Access Journals (Sweden)

    Roberto Castillo

    2015-01-01

    Full Text Available This article is an exploration into the personal aspirations that converge in Guangzhou’s African music scene. I argue that despite being often traversed, articulated, fuelled, and constrained by economies and economic discourses, aspirations are not necessarily economic or rational calculations. I contend that the overarching trading narrative about “Africans in Guangzhou” has left little space for issues of agency, emotion, and aspiration to be considered in their own right. Drawing on a year of continuous ethnographic fieldwork, I show how aspirations are crucial arenas where the rationales behind transnational mobility are developed, reproduced, and transmitted. Indeed, aspirations can be thought of as “navigational devices” (Appadurai 2004 that help certain individuals reach for their dreams. By bringing the analysis of aspirations to the fore, I intend to provide a more complex and nuanced landscape of the multiple rationales behind African presence in Southern China; promote a better understanding (both conceptually and empirically of how individuals navigate their social spaces and guide their transnational journeys; and draw attention to the incessant frictions and negotiations between individual aspirations while on the move and the constraints imposed by more structural imperatives.

  12. Improvisation in West African Musics.

    Science.gov (United States)

    Locke, David

    1980-01-01

    Discussed is music of the sub-Sahara. Vocal, instrumental, and dance drumming from the Sudan Desert, the North Coast, East Horn, Central and West Africa, and contrapuntal yodeling of Pygmies is described. For African musicians, the ability to improvise, and creativity, are gifts from God. Includes selected readings and recordings. (KC)

  13. 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...

  14. Classic African American Children's Literature

    Science.gov (United States)

    McNair, Jonda C.

    2010-01-01

    The purpose of this article is to assert that there are classic African American children's books and to identify a sampling of them. The author presents multiple definitions of the term classic based on the responses of children's literature experts and relevant scholarship. Next, the manner in which data were collected and analyzed in regard to…

  15. 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.

  16. 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

  17. 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.

  18. 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。

  19. 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

  20. 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

  1. Schistosomes in South African penguins.

    Science.gov (United States)

    Aldhoun, Jitka A; Horne, Elizabeth C

    2015-01-01

    During the years 2009-2012, faeces of African penguins (Spheniscus demersus L.) from South African rehabilitation centres were examined for helminths. In total, 46 out 555 samples (8.29 %), mostly belonging to adult birds, were found to contain oval schistosome eggs with a spine on one pole. Their dimensions were 153.21 ± 9.07 × 87.14 ± 8.67 μm. Selected DNA fragments (18S, 28S and ITS rDNA) were sequenced and compared to other schistosome isolates deposited in GenBank. The shape of the eggs suggests that they belong to the genus Gigantobilharzia; however, due to the insufficient stage of knowledge of the genus and limited number of species available for comparison, we were not able to assign the isolate unambiguously to this genus based on either the egg morphology or the results of molecular analysis.

  2. African palm ethno-medicine

    DEFF Research Database (Denmark)

    Gruca, Marta; Blach-Overgaard, Anne; Balslev, Henrik

    2015-01-01

    Ethnopharmacological relevance This study is the first to demonstrate the breadth and patterns of the medicinal applications of African palms. It sheds light on species with the potential to provide new therapeutic agents for use in biomedicine; and links the gap between traditional use of palms...... and pharmacological evaluation for the beneficial effects of palm products on human health. Last but not least, the study provides recommendations for the areas that should be targeted in future ethno-botanical surveys. Aim of the study The primary objective of this survey was to assemble all available ethno-medicinal...... data on African palms, and investigate patterns of palm uses in traditional medicine; and highlight possible under-investigated areas. Materials and methods References were found through bibliographic searches using several sources including PubMed, Embase, and Google Scholar and search engines...

  3. Palaearctic-African Bird Migration

    DEFF Research Database (Denmark)

    Iwajomo, Soladoye Babatola

    Bird migration has attracted a lot of interests over past centuries and the methods used for studying this phenomenon has greatly improved in terms of availability, dimension, scale and precision. In spite of the advancements, relatively more is known about the spring migration of trans......-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 birds from Europe to Africa and opens up the possibility of studying intra-African migration. I have used long-term, standardized autumn ringing data from southeast Sweden to investigate patterns in biometrics, phenology and population trends as inferred from annual trapping totals. In addition, I...

  4. 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...

  5. 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 ...

  6. 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...

  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. 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.

  9. 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.

  10. 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

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. Gentle Africanized bees on an oceanic island.

    Science.gov (United States)

    Rivera-Marchand, Bert; Oskay, Devrim; Giray, Tugrul

    2012-11-01

    Oceanic islands have reduced resources and natural enemies and potentially affect life history traits of arriving organisms. Among the most spectacular invasions in the Western hemisphere is that of the Africanized honeybee. We hypothesized that in the oceanic island Puerto Rico, Africanized bees will exhibit differences from the mainland population such as for defensiveness and other linked traits. We evaluated the extent of Africanization through three typical Africanized traits: wing size, defensive behavior, and resistance to Varroa destructor mites. All sampled colonies were Africanized by maternal descent, with over 65% presence of European alleles at the S-3 nuclear locus. In two assays evaluating defense, Puerto Rican bees showed low defensiveness similar to European bees. In morphology and resistance to mites, Africanized bees from Puerto Rico are similar to other Africanized bees. In behavioral assays on mechanisms of resistance to Varroa, we directly observed that Puerto Rican Africanized bees groomed-off and bit the mites as been observed in other studies. In no other location, Africanized bees have reduced defensiveness while retaining typical traits such as wing size and mite resistance. This mosaic of traits that has resulted during the invasion of an oceanic island has implications for behavior, evolution, and agriculture.

  19. 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...

  20. Fragile states and protection under the 1969 African Refugee Convention

    Directory of Open Access Journals (Sweden)

    Tamara Wood

    2013-05-01

    Full Text Available Current practice in African states highlights both the potential andthe limitations of the 1969 African Refugee Convention in providingprotection to persons displaced from fragile states.

  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. Actigraphy in human African trypanosomiasis as a tool for objective clinical evaluation and monitoring: a pilot study.

    Directory of Open Access Journals (Sweden)

    Alfred K Njamnshi

    Full Text Available BACKGROUND: Human African trypanosomiasis (HAT or sleeping sickness leads to a complex neuropsychiatric syndrome with characteristic sleep alterations. Current division into a first, hemolymphatic stage and second, meningoencephalitic stage is primarily based on the detection of white blood cells and/or trypanosomes in the cerebrospinal fluid. The validity of this criterion is, however, debated, and novel laboratory biomarkers are under study. Objective clinical HAT evaluation and monitoring is therefore needed. Polysomnography has effectively documented sleep-wake disturbances during HAT, but could be difficult to apply as routine technology in field work. The non-invasive, cost-effective technique of actigraphy has been widely validated as a tool for the ambulatory evaluation of sleep disturbances. In this pilot study, actigraphy was applied to the clinical assessment of HAT patients. METHODS/PRINCIPAL FINDINGS: Actigraphy was recorded in patients infected by Trypanosoma brucei gambiense, and age- and sex-matched control subjects. Simultaneous nocturnal polysomnography was also performed in the patients. Nine patients, including one child, were analyzed at admission and two of them also during specific treatment. Parameters, analyzed with user-friendly software, included sleep time evaluated from rest-activity signals, rest-activity rhythm waveform and characteristics. The findings showed sleep-wake alterations of various degrees of severity, which in some patients did not parallel white blood cell counts in the cerebrospinal fluid. Actigraphic recording also showed improvement of the analyzed parameters after treatment initiation. Nocturnal polysomnography showed alterations of sleep time closely corresponding to those derived from actigraphy. CONCLUSIONS/SIGNIFICANCE: The data indicate that actigraphy can be an interesting tool for HAT evaluation, providing valuable clinical information through simple technology, well suited also for long

  3. 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.

  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. 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…

  6. Prostate cancer in men of African origin.

    Science.gov (United States)

    McGinley, Kathleen F; Tay, Kae Jack; Moul, Judd W

    2016-02-01

    Men of African origin are disproportionately affected by prostate cancer: prostate cancer incidence is highest among men of African origin in the USA, prostate cancer mortality is highest among men of African origin in the Caribbean, and tumour stage and grade at diagnosis are highest among men in sub-Saharan Africa. Socioeconomic, educational, cultural, and genetic factors, as well as variations in care delivery and treatment selection, contribute to this cancer disparity. Emerging data on single-nucleotide-polymorphism patterns, epigenetic changes, and variations in fusion-gene products among men of African origin add to the understanding of genetic differences underlying this disease. On the diagnosis of prostate cancer, when all treatment options are available, men of African origin are more likely to choose radiation therapy or to receive no definitive treatment than white men. Among men of African origin undergoing surgery, increased rates of biochemical recurrence have been identified. Understanding differences in the cancer-survivorship experience and quality-of-life outcomes among men of African origin are critical to appropriately counsel patients and improve cultural sensitivity. Efforts to curtail prostate cancer screening will likely affect men of African origin disproportionately and widen the racial disparity of disease.

  7. Understanding the Rise of African Business

    DEFF Research Database (Denmark)

    Jorem, Kaja Tvedten; Hansen, Michael Wendelboe; Jeppesen, Søren

    2014-01-01

    in the literature are identified and an integrative framework for analysing African enterprise development is developed. The framework is used to provide an overview of the received literature on African enterprise development, to identify voids and lacunas and to identify new research agendas. Findings: While...

  8. 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…

  9. The South African National Defence Force

    DEFF Research Database (Denmark)

    Mandrup, Thomas

    2009-01-01

    This research paper is an evaluation of The Souch African National Defence Force´s (SANDF) involvement in Peace Support Operations.......This research paper is an evaluation of The Souch African National Defence Force´s (SANDF) involvement in Peace Support Operations....

  10. 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.

  11. African American Teachers and Culturally Relevant Pedagogy.

    Science.gov (United States)

    Foster, Michele

    An overview is presented of research on African American teachers, addressing the large body of literature written by policy analysts, first-person narratives, and the sociological and anthropological literature. Policy research has identified the small number of African American teachers and has studied some reasons for this shortage and some of…

  12. 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.

  13. 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...

  14. 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...

  15. 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.

  16. 跨越心理距离-高水平建构的作用%TRAVERSING PSYCHOLOGICAL DISTANCE-THE ROLE OF HIGH - LEVEL CONSTRUAL

    Institute of Scientific and Technical Information of China (English)

    王修欣; 杜秀芳

    2016-01-01

    人们是如何跨越心理距离,即如何超越此时、此地的自我的直接经验而对较远心理距离的事物做出反应?CLT 认为,由于高水平建构相较于低水平建构具有相对稳定性,人们对较远心理距离的事物采用高水平建构,进而跨越心理距离。本文在阐述了心理距离概念和建构水平含义的基础上,论述了较远心理距离如何引发高水平建构,以及跨越心理距离所导致的相应的心理和行为结果。未来研究应关注心理距离和建构水平关系的调节变量、跨越心理距离的能力差异与发展以及如何基于 CLT 对人们的心理与行为进行干预和控制。%How do people traverse psychological distance,namely,transcend the direct experience of self in the here and now. Construal level theory proposes that people do so by forming high level,abstract mental representation of distal objects,because abstract construal is more invariant than concrete construal. Future research should pay attention to the moderator of the relationship between psychological distance and construal level,the individual difference and development of the ability of traversing psychological distance,and how to intervene or control people’s mind or behavior in accordance with CLT.

  17. 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

  18. 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…

  19. 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.

  20. 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...

  1. 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.

  2. 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.

  3. 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...

  4. 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.

  5. African Biochemists Plan More Collaboration

    Directory of Open Access Journals (Sweden)

    Peter N. Campbell

    2000-01-01

    Full Text Available The Federation of European Biochemical Societies (FEBS was the first regional organisation of biochemists, holding its first congress in London in 1964. There followed the creation of the Pan American Association of Biochemical Societies (PAABS and then the Federation of Asian and Oceanian Biochemists (FAOB. An obvious development was the formation of a similar organisation to take care of Africa, but this proved impossible so long as apartheid survived in South Africa. With the removal of the latter, the way was clear for the foundation of the Federation of African Societies of Biochemistry and Molecular Biology (FASBMB. The first congress of the new federation was held in Nairobi in September 1996 under the Presidency of Prof. Dominic Makawiti of Nairobi University. Among the 300 participants were representatives from 19 countries in Africa. The second congress was held at Potchefstroom in South Africa in 1998 and the third was just held in Cairo.

  6. 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...

  7. 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.

  8. Antarctic Exploration Parallels for Future Human Planetary Exploration: Science Operations Lessons Learned, Planning, and Equipment Capabilities for Long Range, Long Duration Traverses

    Science.gov (United States)

    Hoffman, Stephen J.

    2012-01-01

    The purpose for this workshop can be summed up by the question: Are there relevant analogs to planetary (meaning the Moon and Mars) to be found in polar exploration on Earth? The answer in my opinion is yes or else there would be no reason for this workshop. However, I think some background information would be useful to provide a context for my opinion on this matter. As all of you are probably aware, NASA has been set on a path that, in its current form, will eventually lead to putting human crews on the surface of the Moon and Mars for extended (months to years) in duration. For the past 50 V 60 years, starting not long after the end of World War II, exploration of the Antarctic has accumulated a significant body of experience that is highly analogous to our anticipated activities on the Moon and Mars. This relevant experience base includes: h Long duration (1 year and 2 year) continuous deployments by single crews, h Established a substantial outpost with a single deployment event to support these crews, h Carried out long distance (100 to 1000 kilometer) traverses, with and without intermediate support h Equipment and processes evolved based on lessons learned h International cooperative missions This is not a new or original thought; many people within NASA, including the most recent two NASA Administrators, have commented on the recognizable parallels between exploration in the Antarctic and on the Moon or Mars. But given that level of recognition, relatively little has been done, that I am aware of, to encourage these two exploration communities to collaborate in a significant way. [Slide 4] I will return to NASA s plans and the parallels with Antarctic traverses in a moment, but I want to spend a moment to explain the objective of this workshop and the anticipated products. We have two full days set aside for this workshop. This first day will be taken up with a series of presentations prepared by individuals with experience that extends back as far as the

  9. African American Men and Prostate Cancer

    Medline Plus

    Full Text Available ... the African-American that we treat this as what it is -- an epidemic. Winston Dyer: My introduction ... being ignorant to prostate cancer -- and not knowing what it was -- that was my first, first, first- ...

  10. Cardiac assessment of African hedgehogs (Atelerix albiventris).

    Science.gov (United States)

    Black, Peter A; Marshall, Cecilia; Seyfried, Alice W; Bartin, Anne M

    2011-03-01

    Cardiomyopathy is a common finding in captive African hedgehogs (Atelerix albiventris) at postmortem exam. To date, treatment attempts have been mostly empirical and unrewarding. The objective of this study was to determine reference cardiac values for captive African hedgehogs based on echocardiogram, electrocardiogram (ECG), and radiographs. Adult African hedgehogs with no clinical signs of cardiac disease (n = 13) were selected. Each animal was anesthetized with isoflurane via facemask and an echocardiogram, ECG, and radiographs were performed. Standard measurements were taken and the descriptive statistics performed. Values were comparable to limited data available in other hedgehog species and other similar-sized exotic species. Two animals were removed from consideration of reference values due to valvular defects that were considered significant. These data are the first establishing cardiac parameters in normal African hedgehogs using radiographic cardiac measurement, echocardiogram, and ECG. Evaluating animals with possible cardiomyopathy may allow for earlier diagnosis and more successful treatment. PMID:22946370

  11. African American Men and Prostate Cancer

    Medline Plus

    Full Text Available ... runs higher. We really don't know. But I would strongly suggest to the African-American that ... then my dad four months later. And then I was told by doctors that I should be ...

  12. Development of 'Serunding' from African catfish

    DEFF Research Database (Denmark)

    Juhari, Nurul Hanisah Binti; MK, Zainol; MM, Masduki

    This research was conducted to develop serunding from African catfish (Clarias gariepinus). Proximate analysis, physical analysis, ascorbic acid analysis, mineral analysis and sensory evaluation were carried out to determine the nutrient compositions and consumer acceptance towards the products. ...

  13. Growth and Institutions in African Development

    OpenAIRE

    Asongu, Simplice A.

    2015-01-01

    Edited by Augustin K. Fosu Routledge Studies in Development Economics, 2015, pp. 393 (Hardcover). Reviewed by Simplice A. Asongu African Governance and Development Institute P.O. Box 8413, Yaoundé, Cameroon.

  14. AN ALTERNATIVE VIEW OF SOUTH AFRICAN ARTILLERY

    Directory of Open Access Journals (Sweden)

    A.C. Lillie

    2012-02-01

    Full Text Available It has been said that 'Necessity is the mother of invention' and there can be few countries, if any, where this is more true than in South Africa.In the late 1930's, prior to World War II, the South African Artillery was severely restricted due to its lack of mobility. The inventiveness shown in tackling this probelm is surely not a thing of the past and the possiblity of adapting South African artillery to current South african needs in warfare should not be overlooked. The South African Defence Force is not able to purchase armament in a free and open market place and the costs of developing new artillery are prohibitive in a country of South Africa's size. it will be argued that it is necessary and possible, in the short term, to take what is currently available and adapt this to South Africa's needs.

  15. African American Men and Prostate Cancer

    Medline Plus

    Full Text Available ... Walker: The researchers don't know exactly why. It is suggested that maybe our diet, maybe our ... African-American that we treat this as what it is -- an epidemic. Winston Dyer: My introduction to ...

  16. The innovative African kilowatt-hour

    International Nuclear Information System (INIS)

    There is a worldwide resurgence of interest in pricing electricity. Whether motivated by deregulation and the treat of competition (as in England and New Zealand) or by restructuring of regulatory goals to encourage competition or conservation (as in the United States), electricity suppliers and distributors are seeing pricing as a means of safeguarding, maintaining, increasing sales. South Africa is no exception in this regard. Past and proposed new developments in electricity pricing in the South African electricity supply industry are discussed, in response to pressures across several fronts: pressures from customers to reduce electricity prices to facilitate growth and survival in the South African economy; the national electrification program; the appointment of the National Electricity Regulator; moves by Southern African electricity utilities to establish a Southern African grid. The current status of electricity pricing, metering, demand profile research and demand management in South Africa are overviewed. (author)

  17. The innovative African kilowatt-hour

    Energy Technology Data Exchange (ETDEWEB)

    Calitz, A.C. [ESKOM, Johannesburg (South Africa)

    1996-12-31

    There is a worldwide resurgence of interest in pricing electricity. Whether motivated by deregulation and the treat of competition (as in England and New Zealand) or by restructuring of regulatory goals to encourage competition or conservation (as in the United States), electricity suppliers and distributors are seeing pricing as a means of safeguarding, maintaining, increasing sales. South Africa is no exception in this regard. Past and proposed new developments in electricity pricing in the South African electricity supply industry are discussed, in response to pressures across several fronts: pressures from customers to reduce electricity prices to facilitate growth and survival in the South African economy; the national electrification program; the appointment of the National Electricity Regulator; moves by Southern African electricity utilities to establish a Southern African grid. The current status of electricity pricing, metering, demand profile research and demand management in South Africa are overviewed. (author).

  18. Contemporary Literature in the African Diaspora

    OpenAIRE

    Barrios Herrero, Olga; Bell, Bernard W.

    1997-01-01

    [ES] El libro es una colección de ensayos divididos entre las tres grandes secciones del libro: Literatura afroamericana, Literatura Afro-caribeña y Afro-latinoamericana y Literatura africana en inglés. [EN] The book is a collection of essays included in the three sections of the book: on African American Literature, Afro-Caribbean and Afro-Latin American Literature and African Literature in English.

  19. Development of 'Serunding' from African catfish

    OpenAIRE

    Juhari, Nurul Hanisah Binti; MK, Zainol; MM, Masduki

    2009-01-01

    This research was conducted to develop serunding from African catfish (Clarias gariepinus). Proximate analysis, physical analysis, ascorbic acid analysis, mineral analysis and sensory evaluation were carried out to determine the nutrient compositions and consumer acceptance towards the products. samples of serunding were prepared with 3 different sizes (30-40cm, 40-50cm, 50-60cm) of African catfish and control was prepared using round scad fish ('ikan selayang') with same amount of fish flesh...

  20. Corynebacterial pneumonia in an African hedgehog.

    Science.gov (United States)

    Raymond, J T; Williams, C; Wu, C C

    1998-04-01

    A 3-mo-old, male African hedgehog (Atelerix albiventris) was anorectic and lethargic for a period of 3 days prior to death. Necropys revealed lungs that were diffusely firm, dark red, and dorsally adhered by fibrinous tags to the pericardial sac. Histopathology revealed necrosuppurative bronchopneumonia with pulmonary abscesses and suppurative pericarditis and myocarditis. A Corynebacterium sp. was isolated from the lungs. We believe this is the first reported case of corynebacterial pneumonia in an African hedgehog. PMID:9577794

  1. Intestinal lymphosarcoma in captive African hedgehogs.

    Science.gov (United States)

    Raymond, J T; Clarke, K A; Schafer, K A

    1998-10-01

    Two captive adult female African hedgehogs (Atelerix albiventris) had inappetance and bloody diarrhea for several days prior to death. Both hedgehogs had ulceration of the small intestine and hepatic lipidosis. Histopathology revealed small intestinal lymphosarcoma with metastasis to the liver. Extracellular particles that had characteristics of retroviruses were observed associated with the surface of some neoplastic lymphoid cells by transmission electron microscopy. These are the first reported cases of intestinal lymphosarcoma in African hedgehogs. PMID:9813852

  2. The african protoproverbial in a multipolar world

    OpenAIRE

    Taiwo, Ọlọruntọba-Oju

    2014-01-01

    The proverb is a rhetorical universal and as such shares features across linguistic, ethnic and culture boundaries, thus making typological distinctions along ethnic or regional lines a daunting task. Further complicating this scenario within the African context is the relentless hybridization and subversion of the African proverb consequent on colonial contact and sundry postcolonial interventions. This twin trajectory, the conceptual universalism of the proverb and the relent...

  3. African American Culture and Hypertension Prevention

    OpenAIRE

    Peters, Rosalind M.; Aroian, Karen J.; Flack, John M.

    2006-01-01

    A qualitative study was done to explore attitudes and beliefs of African Americans regarding hypertension-preventive self-care behaviors. Five focus groups, with 34 participants, were held using interview questions loosely based on the Theory of Planned Behavior (TPB). Analysis revealed themes broadly consistent with the TPB, and also identified an overarching theme labeled “circle of culture.” The circle is a metaphor for ties that bind individuals within the larger African American communit...

  4. Language and Culture in African Postcolonial Literature

    OpenAIRE

    Asante-Darko, Kwaku

    2000-01-01

    In his article, "Language and Culture in African Postcolonial Literature," Kwaku Asante-Darko offers both conceptual basis and empirical evidence in support of the fact that critical issues concerning protest, authenticity, and hybridity in African post-colonial literature have often been heavily laden with nationalist and leftist ideological encumbrances, which tended to advocate the rejection of Western standards of aesthetics. One of the literary ramifications of nationalist/anti-colonial ...

  5. Economic Key to Sino-African Ties

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Following Chinese President Hu Jintao's visit to Africa's Morocco, Nigeria and Kenya in April, Chinese Premier Wen Jiabao is currently visiting seven African countries-Egypt, Ghana, Republic of Congo, Angola, South Africa, Tanzania and Uganda. Haile-Kiros Gessesse, Ethiopia's Ambassador to China, discussed with Beijing Review reporter Ni Yanshuo the future of the Sino-African relationship. As special envoy for the Forum on China-Africa Cooperation, he also expressed his expectations of the forum summit t...

  6. Calibration of a four-hole pyramid probe and area traverse measurements in a short-duration transonic turbine cascade tunnel

    Science.gov (United States)

    Main, A. J.; Day, C. R. B.; Lock, G. D.; Oldfield, M. L. G.

    1996-08-01

    A four-hole pyramid probe has been calibrated for use in a short-duration transonic turbine cascade tunnel. The probe is used to create area traverse maps of total and static pressure, and pitch and yaw angles of the flow downstream of a transonic annular cascade. This data is unusual in that it was acquired in a short-duration (5 s of run time) annular cascade blowdown tunnel. A four-hole pyramid probe was used which has a 2.5 mm section head, and has the side faces inclined at 60° to the flow to improve transonic performance. The probe was calibrated in an ejector driven, perforated wall transonic tunnel over the Mach number range 0.5 1.2, with pitch angles from -20° to + 20° and yaw angles from-23° to +23°. A computer driven automatic traversing mechanism and data collection system was used to acquire a large probe calibration matrix (˜ 10,000 readings) of non dimensional pitch, yaw, Mach number, and total pressure calibration coefficients. A novel method was used to transform the probe calibration matrix of the raw coefficients into a probe application matrix of the physical flow variables (pitch, yaw, Mach number etc.). The probe application matrix is then used as a fast look-up table to process probe results. With negligible loss of accuracy, this method is faster by two orders of magnitude than the alternative of global interpolation on the raw probe calibration matrix. The blowdown tunnel (mean nozzle guide vane blade ring diameter 1.1 m) creates engine representative Reynolds numbers, transonic Mach numbers and high levels (≈ 13%) of inlet turbulence intensity. Contours of experimental measurements at three different engine relevant conditions and two axial positions have been obtained. An analysis of the data is presented which includes a necessary correction for the finite velocity of the probe. Such a correction is non trivial for the case of fast moving probes in compressible flow.

  7. Microbial Ecology of a Crewed Rover Traverse in the Arctic: Low Microbial Dispersal and Implications for Planetary Protection on Human Mars Missions

    Science.gov (United States)

    Schuerger, Andrew C.; Lee, Pascal

    2015-01-01

    Between April 2009 and July 2011, the NASA Haughton-Mars Project (HMP) led the Northwest Passage Drive Expedition (NWPDX), a multi-staged long-distance crewed rover traverse along the Northwest Passage in the Arctic. In April 2009, the HMP Okarian rover was driven 496 km over sea ice along the Northwest Passage, from Kugluktuk to Cambridge Bay, Nunavut, Canada. During the traverse, crew members collected samples from within the rover and from undisturbed snow-covered surfaces around the rover at three locations. The rover samples and snow samples were stored at subzero conditions (-20C to -1C) until processed for microbial diversity in labs at the NASA Kennedy Space Center, Florida. The objective was to determine the extent of microbial dispersal away from the rover and onto undisturbed snow. Interior surfaces of the rover were found to be associated with a wide range of bacteria (69 unique taxa) and fungi (16 unique taxa). In contrast, snow samples from the upwind, downwind, uptrack, and downtrack sample sites exterior to the rover were negative for both bacteria and fungi except for two colony-forming units (cfus) recovered from one downwind (1 cfu; site A4) and one uptrack (1 cfu; site B6) sample location. The fungus, Aspergillus fumigatus (GenBank JX517279), and closely related bacteria in the genus Brevibacillus were recovered from both snow (B. agri, GenBank JX517278) and interior rover surfaces. However, it is unknown whether the microorganisms were deposited onto snow surfaces at the time of sample collection (i.e., from the clothing or skin of the human operator) or via airborne dispersal from the rover during the 12-18 h layovers at the sites prior to collection. Results support the conclusion that a crewed rover traveling over previously undisturbed terrain may not significantly contaminate the local terrain via airborne dispersal of propagules from the vehicle. Key Words: Planetary protection-Contamination-Habitability-Haughton Crater-Mars. Astrobiology

  8. Experimental investigation of photon multiplicity and radiation cooling for 150 GeV electrons/positrons traversing diamond and Si crystals

    Science.gov (United States)

    Kirsebom, K.; Medenwaldt, R.; Mikkelsen, U.; Møller, S. P.; Paludan, K.; Uggerhøj, E.; Worm, T.; Elsener, K.; Ballestrero, S.; Sona, P.; Romano, J.; Connell, S. H.; Sellschop, J. P. F.; Avakian, R. O.; Avetisian, A. E.; Taroian, S. P.

    1996-10-01

    Detailed experimental investigations of photon multiplicities for 150 GeV electrons/positrons traversing thin diamond and Si crystals have been performed. Along axial directions up to 10 photons are emitted in 1.5 mm diamond for a radiative energy loss larger than 4 GeV. This corresponds to a mean free path for photon emission of about two orders of magnitude shorter than in an amorphous target. This is in agreement with an enhanced radiative energy loss of ˜ 30 times that in amorphous targets. The strongly enhanced photon emission leads to radiation cooling which can result in particles exiting the crystal with a reduced angle to the axis. For incidences along planar directions the average multiplicity is still above one, even for the thinnest crystals used in the present experiment, so a single-photon spectrum can only be obtained for thicknesses ≤50 μm, which, on the other hand, is comparable to the coherence lengths for GeV photons, leading to destruction of the coherent effects.

  9. Spatial variability of chemical tracers in surface snow along the traverse route from the coast to 1000 km inland at east Dronning Maud Land, Antarctica

    Institute of Scientific and Technical Information of China (English)

    Toshitaka Suzuki; Yoshinori Iizuka; Teruo Furukawa; Kenichi Matsuoka; Kokichi Kamiyama; Okitsugu Watanabe

    2003-01-01

    We measured the spatial variability of Cl-, Na+, SO2-4, NO-3 and 7Be concentrations in snow cover along the traverse route from S16 to Dome Fuji station in east Dronning Maud Land, Antarctica.The concentrations of Cl- and Na+ at the coast exponentially decreased with distance from the coast up to 200 km inland.Between 200-1000 km inland, the concentrations of Na+ were nearly constant.On the other hand, the concentrations of Cl- increased with distance beyond 750 km inland.Furthermore, the contribution factors between Cl- and Na+ decreased and the Cl-/Na+ ratio and the nssCl-/Cl- ratio increased toward the interior of the continent.These results indicate that sea salt aerosols are transported from the coastal region toward the inland region of the Antarctic continent, and that a source of Cl- other than sea salt exists in the inland plateau of Antarctica.The concentrations of SO2-4, NO-3 and 7Be in snow were relatively high in the coastal region and the inland plateau region compared with those in the katabatic-wind region.

  10. 移动互联网环境下SIP穿越 NAT的研究%Research of NAT Traversal for SIP under Mobile Internet Environment

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

      NAT (Network Address Translation)穿越问题是制约SIP(Session Initiation Protocol )发展的主要障碍之一。分析了ICE(Interactive Connectivity Establishment )方式协助SIP穿越NAT的机制,并根据移动互联网环境的特点对ICE作了进一步改进,最后把改进的ICE作为一个模块成功嵌入到了Android VoIP软件之中。实验证明改进的ICE可使SIP穿越任何NAT ,且有成功率高、低时延的优点,非常适用于移动互联网环境。%NAT (Network Address Translation) traversal is one of the main obstacles restricting the development of SIP(Session Initiation Protocol ) .By analyzing the ICE (Interactive Connectivity Establishment ) method for SIP operating through NAT and the characteristics of the mobile Internet environment ,some further improvements are made to the ICE .Finally ,the improved ICE is embedded as a module into an Android VoIP software successfully . Experiments show that the improved ICE allows SIP to operate through all kinds of NAT with a high success rate and low delay ,and it is ideally suited to the mobile Internet environment .

  11. 图根导线结点网平差软件设计及实现%Designing and Implementation of Mapping Traverse Node Network Adjustment Program

    Institute of Scientific and Technical Information of China (English)

    罗峰; 欧海平; 李长辉; 邢汉发

    2013-01-01

    随着GPS-RTK测量技术的普及,针对“RTK+全站仪”的图根控制网测量模式测设的导线控制网灵活多变。采用“结点法分别平差”数学模型,基于Visual Studio 2005平台的Visual C++语言进行软件编码,借助Microsoft Office Word 2003的OLE组件实现资料输出形成Word文档,形成了图根结点导线网平差软件,通过工程实例验证了程序算法的可靠性和可行性。%With the GPS-RTK measurement technology popularization ,In order to deal with the "RTK+total sta-tion"mapping control network measurement mode ,using the "node method respectively adjustment"mathematical mod-el,carries on the software code Visual Studio Visual 2005 platform based on the C++language,using Microsoft Office Word 2003 an OLE component implements data output form Word document .form the root node traverse network adjust-ment software ,Projects verified the reliability and feasibility of the program algorithm .

  12. Perceptions of African American and European American Teachers on the Education of African American Boys

    Science.gov (United States)

    Bacon, Ellen; Banks, Joy; Young, Kathryn; Jackson, Francesina R.

    2007-01-01

    The authors interviewed 27 teachers (16 African American and 11 European American) on instructional factors contributing to overidentification of behavior problems in African American boys. Interviews focused on teachers' perspectives of effective teachers, teacher-student relationships, and communication styles. Analysis of the interviews showed…

  13. African American Pastors' Beliefs and Actions Regarding Childhood Incest in the African American Community

    Science.gov (United States)

    Wells, Tesia Denis

    2012-01-01

    This quantitative study sought to explore African American pastors' beliefs and actions regarding childhood incest in the African American community and their decisions to inform the proper authorities. This exploratory study was developed in order to draw both public and academic attention to the understudied phenomenon of childhood incest…

  14. Research with African Americans: Lessons Learned about Recruiting African American Women

    Science.gov (United States)

    Coker, Angela D.; Huang, Hsin-Hsin; Kashubeck-West, Susan

    2009-01-01

    The authors briefly explore literature related to recruiting African American research participants, reflect on their experiences conducting body image research with a sample of African American college women in an earlier study (S. Kashubeck-West et al., 2008), and discuss some methodological and cultural challenges that they encountered during…

  15. A SNP test to identify Africanized honeybees via proportion of 'African' ancestry.

    Science.gov (United States)

    Chapman, Nadine C; Harpur, Brock A; Lim, Julianne; Rinderer, Thomas E; Allsopp, Michael H; Zayed, Amro; Oldroyd, Benjamin P

    2015-11-01

    The honeybee, Apis mellifera, is the world's most important pollinator and is ubiquitous in most agricultural ecosystems. Four major evolutionary lineages and at least 24 subspecies are recognized. Commercial populations are mainly derived from subspecies originating in Europe (75-95%). The Africanized honeybee is a New World hybrid of A. m. scutellata from Africa and European subspecies, with the African component making up 50-90% of the genome. Africanized honeybees are considered undesirable for bee-keeping in most countries, due to their extreme defensiveness and poor honey production. The international trade in honeybees is restricted, due in part to bans on the importation of queens (and semen) from countries where Africanized honeybees are extant. Some desirable strains from the United States of America that have been bred for traits such as resistance to the mite Varroa destructor are unfortunately excluded from export to countries such as Australia due to the presence of Africanized honeybees in the USA. This study shows that a panel of 95 single nucleotide polymorphisms, chosen to differentiate between the African, Eastern European and Western European lineages, can detect Africanized honeybees with a high degree of confidence via ancestry assignment. Our panel therefore offers a valuable tool to mitigate the risks of spreading Africanized honeybees across the globe and may enable the resumption of queen and bee semen imports from the Americas. PMID:25846634

  16. Fat, fibre and cancer risk in African Americans and rural Africans

    NARCIS (Netherlands)

    O'Keefe, S.J.; Li, J.V.; Lahti, Leo; Ou, J.; Carbonero, F.; Khaled, M.; Postma, J.M.; Kinross, J.; Wahl, E.; Ruder, E.; Vipperla, K.; Naidoo, V.; Mtshali, L.; Tims, S.; Puylaert, P.G.B.; DeLany, J.; Krasinskas, A.; Benefiel, A.C.; Kaseb, H.O.; Newton, K.; Nicholson, J.K.; Vos, De W.M.; Gaskins, H.R.; Zoetendal, E.G.

    2015-01-01

    Rates of colon cancer are much higher in African Americans (65:100,000) than in rural South Africans (<5:100,000). The higher rates are associated with higher animal protein and fat, and lower fibre consumption, higher colonic secondary bile acids, lower colonic short-chain fatty acid quantities and

  17. Changing Fatherhood: An Exploratory Qualitative Study with African and African Caribbean Men in England

    Science.gov (United States)

    Williams, Robert; Hewison, Alistair; Wildman, Stuart; Roskell, Carolyn

    2013-01-01

    This paper presents findings from a qualitative study undertaken with 46 African and African Caribbean men exploring their experiences of fatherhood. Data analysis was informed by Connell's theoretical work on changing gender relations. Findings indicate that fathers' lives were mediated by masculinities, racism, gender, migration and…

  18. Crossing Cultures in Marriage: Implications for Counseling African American/African Couples

    Science.gov (United States)

    Durodoye, Beth A.; Coker, Angela D.

    2008-01-01

    A wealth of literature exists regarding intermarriage between White and ethnic minority couples. Noticeably lacking, however, is information considering within-group diversity amongst Black couples. This paper will focus on cultural dynamics that may operate with African American and African couples residing in the United States. Through an…

  19. Trade in Educational Services: Reflections on the African and South African Higher Education System

    Science.gov (United States)

    Sehoole, Chika Trevor

    2004-01-01

    This article discusses and analyses the emergence of globalisation and its impact on developments within the African continent. Africa's response at a regional level through the New Partnership for Africa's Development and at a subregional level through the Southern African Development Community's "Protocol on Education" come under scrutiny. These…

  20. "Women ... Mourn and Men Carry on": African Women Storying Mourning Practices--A South African Example

    Science.gov (United States)

    Kotze, Elmarie; Els, Lishje; Rajuili-Masilo, Ntsiki

    2012-01-01

    African mourning of loss of lives in South Africa has been shaped by discursive practices of both traditional African cultures and the sociopolitical developments under apartheid and in post-apartheid South Africa. This article reports on changes in mourning practices on the basis of a literature review and uses a collection of examples to…

  1. 77 FR 37886 - Notice of Intent To Obtain Information Regarding Organizations Who Are Assisting African...

    Science.gov (United States)

    2012-06-25

    ... African Governments To Increase Healthcare Institution Capacity To Maintain Complex Medical Equipment..., which are currently helping African government hospitals, clinics, laboratories, and other African... involved in enhancing the long term ability of African government health institutions to maintain...

  2. Henipavirus RNA in African bats.

    Directory of Open Access Journals (Sweden)

    Jan Felix Drexler

    Full Text Available BACKGROUND: Henipaviruses (Hendra and Nipah virus are highly pathogenic members of the family Paramyxoviridae. Fruit-eating bats of the Pteropus genus have been suggested as their natural reservoir. Human Henipavirus infections have been reported in a region extending from Australia via Malaysia into Bangladesh, compatible with the geographic range of Pteropus. These bats do not occur in continental Africa, but a whole range of other fruit bats is encountered. One of the most abundant is Eidolon helvum, the African Straw-coloured fruit bat. METHODOLOGY/PRINCIPAL FINDINGS: Feces from E. helvum roosting in an urban setting in Kumasi/Ghana were tested for Henipavirus RNA. Sequences of three novel viruses in phylogenetic relationship to known Henipaviruses were detected. Virus RNA concentrations in feces were low. CONCLUSIONS/SIGNIFICANCE: The finding of novel putative Henipaviruses outside Australia and Asia contributes a significant extension of the region of potential endemicity of one of the most pathogenic virus genera known in humans.

  3. Africans and Black Americans in the United States: Social Distance and Differential Acculturation.

    Science.gov (United States)

    Emoungu, Paul-Albert

    1992-01-01

    Presents an exploratory examination of the causes of social distance characterizing the association between Africans and African Americans. African American's perceptions about Africa and Africans are assessed through anecdotes and impressions, and thoughts and criticisms of Africans about African Americans are considered. A social science…

  4. Static and Dynamic Traversable Wormholes

    Science.gov (United States)

    Adamiak, Jaroslaw P.

    2008-09-01

    The aim of this work is to discuss the effects found in static and dynamic wormholes that occur as a solution of Einstein equations in general relativity. The ground is prepared by presentation of faster than light effects, then the focus is narrowed to Morris-Thorne framework for a static spherically symmetric wormhole. Two types of dynamic worm-holes, evolving and rotating, are considered.

  5. Trypanotolerance in N’Dama x Boran crosses under natural trypanosome challenge: effect of test-year environment, gender, and breed composition

    Directory of Open Access Journals (Sweden)

    Orenge Caleb O

    2012-10-01

    Full Text Available Abstract Background Trypanosomosis, a protozoal disease affecting livestock, transmitted by Glossina (tsetse flies is a major constraint to agricultural production in Sub-Saharan Africa. It is accepted that utilization of the native trypanotolerance exhibited in some of the African cattle breeds to improve trypanotolerance of more productive but susceptible breeds, will offer a cost effective and sustainable solution to the problem. The success of this approach is based on the premise that quantitative trait loci previously identified under relatively controlled situations confer useful trypanotolerance under natural field situations. As part of a study to authenticate this hypothesis, a population of 192 cattle, consisting of six batches of N’Dama and Kenya-Boran backcross animals [(N’Dama x Kenya-Boran x Kenya-Boran] born over the period 2002 to 2006 was constructed. Some of the batches also included pure Kenya-Boran cattle, or N’Dama x Kenya- Boran F1 animals. Each batch was exposed as yearlings to natural field trypanosomosis challenge over a period of about one year; the entire challenge period extending from December 2003 to June 2007. Performance of the animals was evaluated by weekly or biweekly measurements of body weight, packed blood cell volume (PCV, parasitemia score, and number of trypanocide treatments. From these basic data, 49 phenotypes were constructed reflecting dynamics of body weight, packed cell volume (PCV and parasitemia under challenge. Results Females were distinctly more trypanotolerant than males. F1, backcross and pure Kenya- Boran animals ranked in that order with respect to trypanotolerance. Overall batch effects were highly significant (p Conclusions The results show that trypanotolerance derived from the N’Dama is expressed under field conditions; and that the trait is primarily additive in nature, being expressed in heterozygous condition and in a three-quarters Boran genetic background. The results

  6. Afro-Americans and Early Pan-Africanism

    Science.gov (United States)

    Contee, Clarence G.

    1970-01-01

    History of the Pan-African movement, the roles of W.E.B.Du Bois and Marcus Garvey in the movement activities, and the shift to African based leadership of the movement in the 1940's are discussed. (KG)

  7. What about African Americans and High Blood Pressure?

    Science.gov (United States)

    ANSWERS by heart Lifestyle + Risk Reduction High Blood Pressure What About African Americans and High Blood Pressure? The prevalence of high blood pressure in African Americans is among the highest in ...

  8. Men of African Descent and Carcinoma of the Prostate Consortium

    Science.gov (United States)

    The Men of African Descent and Carcinoma of the Prostate Consortium collaborates on epidemiologic studies to address the high burden of prostate cancer and to understand the causes of etiology and outcomes among men of African ancestry.

  9. Sculpture of decorative candlestick based on African totem masks

    Directory of Open Access Journals (Sweden)

    Sofronova Nadezhda

    2015-04-01

    Full Text Available The paper deals with the decorative small sculptures and African totem masks, their artistic and stylistic fea-tures, analysis of the works of sculptors and steps for creating a decorative candlestick based on African totem masks.

  10. Geologic Interpretation of Data Sets Collected by Planetary Analog Geology Traverses and by Standard Geologic Field Mapping. Part 1; A Comparison Study

    Science.gov (United States)

    Eppler, Dean B.; Bleacher, Jacob F.; Evans, Cynthia A.; Feng, Wanda; Gruener, John; Hurwitz, Debra M.; Skinner, J. A., Jr.; Whitson, Peggy; Janoiko, Barbara

    2013-01-01

    Geologic maps integrate the distributions, contacts, and compositions of rock and sediment bodies as a means to interpret local to regional formative histories. Applying terrestrial mapping techniques to other planets is challenging because data is collected primarily by orbiting instruments, with infrequent, spatiallylimited in situ human and robotic exploration. Although geologic maps developed using remote data sets and limited "Apollo-style" field access likely contain inaccuracies, the magnitude, type, and occurrence of these are only marginally understood. This project evaluates the interpretative and cartographic accuracy of both field- and remote-based mapping approaches by comparing two 1:24,000 scale geologic maps of the San Francisco Volcanic Field (SFVF), north-central Arizona. The first map is based on traditional field mapping techniques, while the second is based on remote data sets, augmented with limited field observations collected during NASA Desert Research & Technology Studies (RATS) 2010 exercises. The RATS mission used Apollo-style methods not only for pre-mission traverse planning but also to conduct geologic sampling as part of science operation tests. Cross-comparison demonstrates that the Apollo-style map identifies many of the same rock units and determines a similar broad history as the field-based map. However, field mapping techniques allow markedly improved discrimination of map units, particularly unconsolidated surficial deposits, and recognize a more complex eruptive history than was possible using Apollo-style data. Further, the distribution of unconsolidated surface units was more obvious in the remote sensing data to the field team after conducting the fieldwork. The study raises questions about the most effective approach to balancing mission costs with the rate of knowledge capture, suggesting that there is an inflection point in the "knowledge capture curve" beyond which additional resource investment yields progressively

  11. 直线电机在立体车库横移装置中的应用%Linear motor in the stereo garage traverse device

    Institute of Scientific and Technical Information of China (English)

    陈婵娟; 任晓锋

    2014-01-01

    本文通过分析现有塔式立体车库横移装置存在的问题,设计由直线电机代替原旋转电机的新横移装置布局,采用Pro/Engineer Wildfire 5.0进行三维模型设计、Workbench对重要零件进行力学仿真验证.利用直线电机可直接输出直线运动,通过初级滑块上安装的垂直立柱结构将驱动力传递至负载,设计尺寸使各部件位置无干涉现象以保障横移正确.该研究使塔式立体车库横移装置结构更紧凑,制动精度更高,降低了对进口部件的依赖程度.%This paper analyzed for the tower parking garage traverse device .Original prototype device ,instead of the original linear motor by the rotation of the motor .Determine the layout of the new device .Using Pro /Engineer Wildfire 5 .0 for three-dimensional model design , workbench to important parts for mechanical imitation .Linear motion can be output by linear motor directly .Transfer driving force to the load by the pillar that installing primary slider . Design size without interference in the position of parts for transverse right .The study made the tower parking garage make more compact sliding .Accuracy is improved braking .Reduc-ing the need to import key components of dependence .

  12. Visualisation of γH2AX foci caused by heavy ion particle traversal; distinction between core track versus non-track damage.

    Directory of Open Access Journals (Sweden)

    Nakako Izumi Nakajima

    Full Text Available Heavy particle irradiation produces complex DNA double strand breaks (DSBs which can arise from primary ionisation events within the particle trajectory. Additionally, secondary electrons, termed delta-electrons, which have a range of distributions can create low linear energy transfer (LET damage within but also distant from the track. DNA damage by delta-electrons distant from the track has not previously been carefully characterised. Using imaging with deconvolution, we show that at 8 hours after exposure to Fe (∼200 keV/µm ions, γH2AX foci forming at DSBs within the particle track are large and encompass multiple smaller and closely localised foci, which we designate as clustered γH2AX foci. These foci are repaired with slow kinetics by DNA non-homologous end-joining (NHEJ in G1 phase with the magnitude of complexity diminishing with time. These clustered foci (containing 10 or more individual foci represent a signature of DSBs caused by high LET heavy particle radiation. We also identified simple γH2AX foci distant from the track, which resemble those arising after X-ray exposure, which we attribute to low LET delta-electron induced DSBs. They are rapidly repaired by NHEJ. Clustered γH2AX foci induced by heavy particle radiation cause prolonged checkpoint arrest compared to simple γH2AX foci following X-irradiation. However, mitotic entry was observed when ∼10 clustered foci remain. Thus, cells can progress into mitosis with multiple clusters of DSBs following the traversal of a heavy particle.

  13. Attempts at a web presence inventory of African minority languages

    OpenAIRE

    Gee, Quintin

    2006-01-01

    Making an inventory of minority languages that have web sites is difficult. We show that, even if we define “minority” as African languages, then this is of little use since the appearance of web sites in any African languages are few. Many African web sites are hosted outside the continent, and few have totally indigenous languages displayed; rather, it contains a mixture of ex-colonial language illustrating documents in the African language concerned. In addition, many countries have more t...

  14. Lift every voice: voices of African-American lesbian elders.

    Science.gov (United States)

    Woody, Imani

    2015-01-01

    Old lesbians of African descent have experienced racism, heterosexism, homophobia, and ageism. This article explores the topics of aging, ageism, heterosexism, and minority stress among older African-American lesbians. The narratives and subsequent analysis offer significant contributions to the dialogue regarding Black aging lesbians in the aging and lesbian, gay, bisexual, and transgender (LGBT) communities generally and in the African-American and African-American lesbian communities specifically.

  15. On Cultural and Academic Exchanges Between China and African Countries

    OpenAIRE

    Charles Kabwete Mulinda

    2015-01-01

    Cooperation between China and African countries has often been portrayed as an economic one. Despite multiple exchanges in the area of culture and knowledge production, not much is written about chinese culture in Africa or knowledge production interaction between both China and African countries. Just to give an example, each African major town has chinese restaurants and Africans like chinese food. But food is seen as an economic asset, not a cultural one. Chinese cuisine is not enough take...

  16. Psychology and Ubuntu : therapeutic meetings in a South African context

    OpenAIRE

    2008-01-01

    The purpose of this study was to explore therapeutic meetings in a South African context. Utilising a qualitative research method, I have examined how South African therapists work in a multicultural context, asking questions regarding challenges the therapists met, what elements existed in the African context that influence healing. I proposed that the concept of Ubuntu could provide an African perspective to balance the western notion of psychotherapy. I also explored what adjustments thera...

  17. Population Genomics of sub-saharan Drosophila melanogaster: African diversity and non-African admixture.

    Directory of Open Access Journals (Sweden)

    John E Pool

    Full Text Available Drosophila melanogaster has played a pivotal role in the development of modern population genetics. However, many basic questions regarding the demographic and adaptive history of this species remain unresolved. We report the genome sequencing of 139 wild-derived strains of D. melanogaster, representing 22 population samples from the sub-Saharan ancestral range of this species, along with one European population. Most genomes were sequenced above 25X depth from haploid embryos. Results indicated a pervasive influence of non-African admixture in many African populations, motivating the development and application of a novel admixture detection method. Admixture proportions varied among populations, with greater admixture in urban locations. Admixture levels also varied across the genome, with localized peaks and valleys suggestive of a non-neutral introgression process. Genomes from the same location differed starkly in ancestry, suggesting that isolation mechanisms may exist within African populations. After removing putatively admixed genomic segments, the greatest genetic diversity was observed in southern Africa (e.g. Zambia, while diversity in other populations was largely consistent with a geographic expansion from this potentially ancestral region. The European population showed different levels of diversity reduction on each chromosome arm, and some African populations displayed chromosome arm-specific diversity reductions. Inversions in the European sample were associated with strong elevations in diversity across chromosome arms. Genomic scans were conducted to identify loci that may represent targets of positive selection within an African population, between African populations, and between European and African populations. A disproportionate number of candidate selective sweep regions were located near genes with varied roles in gene regulation. Outliers for Europe-Africa F(ST were found to be enriched in genomic regions of locally

  18. South African Artillery in the Eighties

    Directory of Open Access Journals (Sweden)

    A. C. Lillie

    2012-02-01

    Full Text Available Emerging from the Second World War armed with the then completely adequate 25 pounder and BL 5.5" guns, the South African Field Artillery continued to use the same guns operationally over thirty years later.When the armed forces of South Africa were thrown into a conventional conflict during the Angolan Civil War in 1975, the gunners found their equipment to be woefully inadequate. Soviet made artillery systems in the hands of the Russian-backed forces possessed ranges far in excess of the Second World War vintage South African systems and brought home in a very real way the need for drastic modernisation of the artillery branch of the South African Army.

  19. What is Ubuntu? Different Interpretations among South Africans of African Descent

    DEFF Research Database (Denmark)

    Gade, Christian B.N.

    2012-01-01

    In this article, I describe and systematize the different answers to the question 'What is Ubuntu?' that I have been able to identify among South Africans of African descent (SAADs). I show that it is possible to distinguish between two clusters of answers. The answers of the first cluster all...... define ubuntu as a moral quality of a person, while the answers of the second cluster all define ubuntu as a phenomenon (for instance a philosophy, an ethic, African humanism, or, a wordview) according to which persons are interconnected. The concept of a person is of central importance to all the...

  20. Assessing the contributions of East African and West Pacific warming to the 2014 boreal spring East African drought

    Science.gov (United States)

    Funk, Christopher C.; Shukla, Shraddhanand; Hoell, Andrew; Livneh, Ben

    2015-01-01

    Anthropogenic warming contributed to the 2014 East African drought by increasing East African and west Pacific temperatures, and increasing the gradient between standardized western and central Pacific SST causing reduced rainfall, evapotranspiration, and soil moisture.