4,020 research outputs found

    Assessment of heavy metal pollution in soils along major roadside areas in Botswana

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    Assessment of heavy metal pollutants: Al, Co, Cu, Fe, Pb, Mn, Ni and Zn was conducted along major roadside soils of Botswana, lying between latitudes 18°S to 27°S and longitudes 20°E to 29°E using enrichment factor ratios (EF), contamination factor (CF), pollution load index (PLI) and geoaccumulation index (Igeo) methods. The studied sites were demarcated into five zones referred to as FN (Francistown-Nata), NM (Nata-Maun), MG (Maun-Ghanzi), GK (Ghanzi-Kang) and TS (Tshabong-Sekoma). All the four pollution assessment methods revealed that zones FN, NM and MG are pollution impacted as compared to GK and TS zones. Results of multivariate analysis suggest mixed origins of pollution sources including human activities, vehicular emissions and lithogenic occurrences. Al, Cu, Fe, Mn, Zn and Co is of mixed origins of pollutants, with Fe and Mn being predominantly lithogenic, and vehicular emissions characterised by Pb and Ni. The findings in this study will serve to create awareness of vehicular heavy metal pollution to Botswana policy makers in the mitigation of vehicular pollution, as it is barely monitored.Key words: Heavy metal contamination, roadside soils, enrichment factors, contamination factor, pollution load index, geoaccumulation index, cluster analysis, factor analysis

    Morphology of colorectal carcinoma among Nigerians: A 30-year review

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    Background: The incidence of colorectal carcinoma has been on the increase in the developing countries, including Nigeria, as a result of change in diet and adoption of western lifestyle.Objectives: The aim of this review is to highlight the prevalence, age and sex distribution, anatomical location, and morphological characteristics of colorectal carcinomas in Ilorin, Nigeria.Materials and Methods: This is a retrospective study of all cases of histologically diagnosed colorectal carcinoma in the University of Ilorin Teaching Hospital, Ilorin, Nigeria, over a 30-year period (January 1979–December 2008), using the departmental record and histological slides of the cases.Result: A total of 241 cases of colorectal carcinoma were reported, 144 cases (60%) in males and 96 cases (40%) in females with a male: female ratio of 1.5:1. The peak age of occurrence for males was between 51 and 60 years, while that of the females was between 41 and 50 years. The malignancy was found in the rectum in 60.2% of the cases, while the least affected site is the descending colon (1.2%). The exophytic occluding masses were found in 82.2% of the cases, and the most common histological type is adenocarcinoma (77.2%) with well-, moderately, and poorly differentiated forms constituting 52.3%, 32.8%, and 14.9% respectively. Of the 241 cases that were seen over the last 30 years, 93 cases (38.6%) were seen in the last 5 years.Conclusion: Colorectal carcinoma is no longer a rare disease in Nigeria. The surge in the incidence reported in the last 5 years in this center calls for a pragmatic action in its control, with emphasize on colonoscopic  screening for those with family history, and possibly making digital rectal examination a mandatory aspect of clinical examination, because most colorectal carcinomas are within the reach of examining finger

    Telomere length regulation: coupling DNA end processing to feedback regulation of telomerase

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    The conventional DNA polymerase machinery is unable to fully replicate the ends of linear chromosomes. To surmount this problem, nearly all eukaryotes use the telomerase enzyme, a specialized reverse transcriptase that utizes its own RNA template to add short TG-rich repeats to chromosome ends, thus reversing their gradual erosion occurring at each round of replication. This unique, non-DNA templated mode of telomere replication requires a regulatory mechanism to ensure that telomerase acts at telomeres whose TG tracts are too short, but not at those with long tracts, thus maintaining the protective TG repeat cap at an appropriate average length. The prevailing notion in the field is that telomere length regulation is brought about through a negative feedback mechanism that counts TG repeat-bound protein complexes to generate a signal that regulates telomerase action. This review summarizes experiments leading up to this model and then focuses on more recent experiments, primarily from yeast, that begin to suggest how this counting mechanism might work. The emerging picture is that of a complex interplay between the conventional DNA replication machinery, DNA damage response factors, and a specialized set of proteins that help to recruit and regulate the telomerase enzyme

    Réponse à la double inoculation mycorhizienne et rhizobienne du niébé (variété, KVX396-4-5-2D) cultivé au Burkina Faso

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    Le niébé vit en symbiose avec des champignons mycorhiziens arbusculaires (CMA) et rhizobiums du sol susceptibles d’améliorer sa nutrition hydrominérale et sa croissance. Cette étude avait pour objectif d’évaluer la réponse du niébé (variété KVX 396-4-5-2D) à l’inoculation rhizobienne et/ou mycorhizienne. KVX 396-4-5-2D (KVX) a été inoculée en serre avec cinq inoculums de CMA [Glomus aggregatum (Ga), Glomus mossae (Gm), Rhizophagus irregularis (Ri), Glomus fasciculatum (Gf), Glomus verrucullosum (Gv)] et une souche de rhizobium (ORS 3409). Après 45 jours de culture, les plants ont été récoltés et les paramètres de croissance (hauteur et biomasses), de mycorhization et de nodulation ont été mesurés. Les résultats montrent que l’inoculation améliore la croissance en hauteur et la biomasse totale des plants de KVX. La souche Ga améliore de 70% la production de biomasse totale de KVX. Aussi, la double inoculation ORS3409+Ga est plus bénéfique aux plants de la variété de niébé utilisée avec une amélioration de la croissance en hauteur de 8,82%. De ces résultats, il ressort que l’inoculum Ga améliore significativement la croissance de la variété de niébé KVX au stade floraison-fructification.Mots clés : Champignons mycorhiziens arbusculaires, rhizobium, inoculation, niébé

    Parent formulation at the Lagrangian level

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    The recently proposed first-order parent formalism at the level of equations of motion is specialized to the case of Lagrangian systems. It is shown that for diffeomorphism-invariant theories the parent formulation takes the form of an AKSZ-type sigma model. The proposed formulation can be also seen as a Lagrangian version of the BV-BRST extension of the Vasiliev unfolded approach. We also discuss its possible interpretation as a multidimensional generalization of the Hamiltonian BFV--BRST formalism. The general construction is illustrated by examples of (parametrized) mechanics, relativistic particle, Yang--Mills theory, and gravity.Comment: 26 pages, discussion of the truncation extended, typos corrected, references adde

    Toward High-Precision Measures of Large-Scale Structure

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    I review some results of estimation of the power spectrum of density fluctuations from galaxy redshift surveys and discuss advances that may be possible with the Sloan Digital Sky Survey. I then examine the realities of power spectrum estimation in the presence of Galactic extinction, photometric errors, galaxy evolution, clustering evolution, and uncertainty about the background cosmology.Comment: 24 pages, including 11 postscript figures. Uses crckapb.sty (included in submission). To appear in ``Ringberg Workshop on Large-Scale Structure,'' ed D. Hamilton (Kluwer, Amsterdam), p. 39

    Many-particle entanglement with Bose--Einstein condensates

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    We propose a method to produce entangled states of several particles starting from a Bose-Einstein condensate. In the proposal, a single fast π/2\pi/2 pulse is applied to the atoms and due to the collisional interaction, the subsequent free time evolution creates an entangled state involving all atoms in the condensate. The created entangled state is a spin-squeezed state which could be used to improve the sensitivity of atomic clocks.Comment: 4 pages. Minor modification

    Gauge fields in (A)dS within the unfolded approach: algebraic aspects

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    It has recently been shown that generalized connections of the (A)dS space symmetry algebra provide an effective geometric and algebraic framework for all types of gauge fields in (A)dS, both for massless and partially-massless. The equations of motion are equipped with a nilpotent operator called σ\sigma_- whose cohomology groups correspond to the dynamically relevant quantities like differential gauge parameters, dynamical fields, gauge invariant field equations, Bianchi identities etc. In the paper the σ\sigma_--cohomology is computed for all gauge theories of this type and the field-theoretical interpretation is discussed. In the simplest cases the σ\sigma_--cohomology is equivalent to the ordinary Lie algebra cohomology.Comment: 59 pages, replaced with revised verio
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