699 research outputs found

    Comparative anatomical studies of responses of some roadside plants to highway automobile exhausts

    Get PDF
    Urena lobata and Hyptis suaveolens growing along busy roadsides in Lafia, Nigeria were carefully sampled. This was with a view to investigate the effect of continuous impact of automobile exhausts on internal structures of the plants. Three major highways were chosen for study in Lafia. Plant samples were systematically collected in replicates from 0 m, 10 m and 20 m away from defined points of the roadsides. Leaf and stem anatomical sections were prepared for microscopic examinations following established procedures. The plants were observed to have more stomata and smaller area of guard cells at 0 m than those away from the roadsides. For H. suaveolens, the thickness of epidermis, thickness of vascular bundles, length and number of trichomes at 0 m are higher than those at 10 m and 20 m. The reverse was observed for U. lobata. However, U. lobata showed high number of parenchyma cells closer to the roadsides than those father away. Consequently, H. suaveolens seemed to have ability to withstand and thrive well in areas of heavy air pollution. These anatomical changes were described to be distinct with regards to individual species and could have been as a result of cumulative effects of air pollutants.Keywords: Air pollutants, Anatomy, Hyptis suaveolens, Lafia, Urena lobat

    Random walk on the range of random walk

    Get PDF
    We study the random walk X on the range of a simple random walk on â„€ d in dimensions d≄4. When d≄5 we establish quenched and annealed scaling limits for the process X, which show that the intersections of the original simple random walk path are essentially unimportant. For d=4 our results are less precise, but we are able to show that any scaling limit for X will require logarithmic corrections to the polynomial scaling factors seen in higher dimensions. Furthermore, we demonstrate that when d=4 similar logarithmic corrections are necessary in describing the asymptotic behavior of the return probability of X to the origin

    Behavior of polyethylene-based nanocomposites containing multi-layer graphene filler

    Get PDF
    open4siIn this research, the results regarding the characterization of electrical and mechanical properties of a low-density polyethylene (LDPE) - graphene-like (G) nanocomposite are presented. The processing technique used to fabricate the material was high-energy ball milling. This method was utilized to fabricate samples with a filler loading ranging from 1 wt% up to 7wt%. Low voltage broadband dielectric spectroscopy (BDS), erosion tests and breakdown tests (BD) were the measurements carried out in order to characterize the electrical behavior of the fabricated composites. Then, some of the mechanical properties of the LDPE-G nanocomposites were determined with dynamic mechanical analysis (DMA) and, finally, the crystalline structure of the material was investigated with differential scanning calorimetry (DSC).embargoed_20200114Rosi, G.F.; Frechette, M.; David, E.; Fabiani, D.Rosi, G.F.; Frechette, M.; David, E.; Fabiani, D

    Phyto-extraction ability of Digitaria exilis (Fonio) to heavy metals

    Get PDF
    Among the different contaminants in the environment, heavy metals are unique due to the fact that they cannot be broken down to non-toxic forms. The research was conducted to determine the remediation potential of Digitaria exilis and to identify the varieties that can tolerate heavy metals contamination. Soil was collected in an Automobile mechanic workshop, Government Reserved Area (GRA) Ado-Ekiti. Five kilograms (5 kg) of soils collected was air dried, sieved and filled into plastic buckets. The experiment was a completely randomized designed with three replicates. Three different accessions of Digitaria exilis namely; Jakah D Iburua (JAK), Dinat D Iburua (DID) and Jiw D Iburau (JIW) were planted. Soils were watered till field moisture capacity. Plant height was determined every two weeks after planting. Soil analysis was carried out to determine the physical and chemical properties before and after the experiment. Heavy metals including Cd, Fe, Zn, Pb, As and Cu were determined in the plant roots and shoots using Atomic Absorption Spectrophotometer (AAS). Accession JAK Bio-accumulated heavy-metals in their root than shoot, consequently, significant high plant height was recorded. However, shoot of accession JAK accumulated 22 % Pb, 46.78% Cu and 37.5% Cd and 20.3% Zn than others whereas accession DID accumulated As than accession JAK. Therefore, accession JAK demonstrated highest phyto-extraction of heavy-metals potentials at the root. Variety JIW has the lowest plant height, root and shoots heavy metals accumulation. Although heavy metals contaminated soil affected the growth of D. exilis, nevertheless accession JAK has the highest productivity under this condition and can be further recommended in phyto-extraction of heavy-metals in polluted sites.Keywords: Phyto-extraction, Digitaria exilis and Heavy-metal

    Band-dependent quasiparticle dynamics in the hole-doped Ba-122 iron pnictides

    Get PDF
    We report on band-dependent quasiparticle dynamics in the hole-doped Ba-122 pnictides measured by ultrafast pump-probe spectroscopy. In the superconducting state of the optimal and over hole-doped samples, we observe two distinct relaxation processes: a fast component whose decay rate increases linearly with excitation density and a slow component whose relaxation is independent of excitation strength. We argue that these two components reflect the recombination of quasiparticles in the two hole bands through intraband and interband processes. We also find that the thermal recombination rate of quasiparticles increases quadratically with temperature in all samples. The temperature and excitation density dependence of the decays indicates fully gapped hole bands and nodal or very anisotropic electron bands.United States. Department of Energy (Grant No. DE-FG02-08ER46521)National Science Foundation (U.S.). Materials Research Science and Engineering Centers (Program) (award number DMR - 0819762

    Modular assembly with postponement to improve health, safety, and productivity in construction

    Get PDF
    This paper presents the outcome of an engineering study as part of the design and development of a lean and agile construction system and in particular its supply chain component. This combines modular assembly with a postponement function to be tested on a case study project (not reported here), the objective of which is to improve health, safety, and productivity for the company sponsoring the research. The contribution to research is the combination of countermeasures described in this paper that have been developed and incorporated into a wider construction system, in the same way that manufacturing has used this strategy with great success. A further output is the development and use of an innovative method for assembling, transporting, and installing mechanical and electrical modules, whereby modularization can be achieved with or without offsite manufacturing capability. The research forecasts a reduction of onsite labor of 35% compared to using traditional methods of construction, with less onsite operatives at risk of injury carrying out simpler assembly tasks within ergonomic mobile work cells. Further research is proposed to measure the benefits of the construction system following its implementation on a case study project

    The burden of proof: the current state of atrial fibrillation prevention and treatment trials

    Get PDF
    Atrial fibrillation (AF) is an age-related arrhythmia of enormous socioeconomic significance. In recent years, our understanding of the basic mechanisms that initiate and perpetuate AF has evolved rapidly, catheter ablation of AF has progressed from concept to reality, and recent studies suggest lifestyle modification may help prevent AF recurrence. Emerging developments in genetics, imaging, and informatics also present new opportunities for personalized care. However, considerable challenges remain. These include a paucity of studies examining AF prevention, modest efficacy of existing antiarrhythmic therapies, diverse ablation technologies and practice, and limited evidence to guide management of high-risk patients with multiple comorbidities. Studies examining the long-term effects of AF catheter ablation on morbidity and mortality outcomes are not yet completed. In many ways, further progress in the field is heavily contingent on the feasibility, capacity, and efficiency of clinical trials to incorporate the rapidly evolving knowledge base and to provide substantive evidence for novel AF therapeutic strategies. This review outlines the current state of AF prevention and treatment trials, including the foreseeable challenges, as discussed by a unique forum of clinical trialists, scientists, and regulatory representatives in a session endorsed by the Heart Rhythm Society at the 12th Global CardioVascular Clinical Trialists Forum in Washington, DC, December 3–5, 2015

    Electrocardiographic characteristics in patients with heart failure and normal ejection fraction: a systematic review and meta‐analysis

    Get PDF
    Background: Little is known about ECG abnormalities in patients with heart failure and normal ejection fraction (HeFNEF) and how they relate to different etiologies or outcomes. Methods and Results: We searched the literature for peer‐reviewed studies describing ECG abnormalities in HeFNEF other than heart rhythm alone. Thirty five studies were identified and 32,006 participants. ECG abnormalities reported in patients with HeFNEF include atrial fibrillation (prevalence 12%–46%), long PR interval (11%–20%), left ventricular hypertrophy (LVH, 10%–30%), pathological Q waves (11%–18%), RBBB (6%–16%), LBBB (0%–8%), and long JTc (3%–4%). Atrial fibrillation is more common in patients with HeFNEF compared to those with heart failure and reduced ejection fraction (HeFREF). In contrast, long PR interval, LVH, Q waves, LBBB, and long JTc are more common in patients with HeFREF. A pooled effect estimate analysis showed that QRS duration ≄120 ms, although uncommon (13%–19%), is associated with worse outcomes in patients with HeFNEF. Conclusions: There is high variability in the prevalence of ECG abnormalities in patients with HeFNEF. Atrial fibrillation is more common in patients with HeFNEF compared to those with HeFREF. QRS duration ≄120 ms is associated with worse outcomes in patients with HeFNEF. Further studies are needed to address whether ECG abnormalities correlate with different phenotypes in HeFNEF

    Effect of processing variables and bulk composition on the surface composition of spray dried powders of a model food system

    Get PDF
    Abstract The surface compositions of food powders created from spray drying solutions containing various ratios of sodium caseinate, maltodextrin and soya oil have been analysed by Electron Spectroscopy for Chemical Analysis. The results show significant enrichment of oil at the surface of particles compared to the bulk phase and, when the non-oil components only are considered, a significant surface enrichment of sodium caseinate also. The degree of surface enrichment of both oil and sodium caseinate was found to increase with decreasing bulk levels of the respective components. Surface enrichment of oil was also affected by processing conditions (emulsion drop size and drying temperature), but surface enrichment of sodium caseinate was relatively insensitive to these. The presence of "pock marks" on the particle surfaces strongly suggests that the surface oil was caused by rupturing of emulsion droplets at the surface as the surrounding matrix contracts and hardens

    Sequential Analysis: A Methodology for Monitoring Approval Plans

    Get PDF
    published or submitted for publicatio
    • 

    corecore