13,848 research outputs found

    Using trees as urban heat island reduction tool in Enugu city Nigeria based on their air pollution tolerance index

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    The Study examined the air pollution tolerance indices (APTI) of five plant species around Enugu urban area. Four physiological and biological parameters including leaf relative water content (RWC), ascorbic acid (AA) content, total leaf chlorophyll (TCh), and leaf extract pH were used to develop an APTI. The vegetation monitoring in terms of its APTI acts as a ‘Bioindicator’ of air pollution and can be incorporated into assessment studies for selecting trees for urban heat island (UHI) mitigation strategy.The result of the APTI showed order of tolerance as Anacarduim occidentale (22.20), Pinus spp (22.35), Catalpa burgei (22.57), Mangifera indica (23.37), and Psiduim guajava (24.15). A comparative analysiswas also done between the shedding ability of these trees and their APTI. The result showed that the best tree that provides both shed and high air pollution tolerance appeared in that order: Psiduim guajava, Magifera indica, Catalpa burgei, Pinus spp and Anacarduim occidentale. The results of such studies are therefore handy for future planning, and as well provide tolerant species for landscape and urban heat island mitigation

    Premature ovarian insufficiency: the need for evidence on the effectiveness of hormonal therapy

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    Premature ovarian insufficiency (POI) – the loss of ovarian function before the age of 40 years, a decade before natural menopause – is a life-changing diagnosis for women. POI causes significant short-term and long-term morbidity related to estrogen deficiency. The condition is managed by providing exogenous estrogen replacement, usually as the oral contraceptive pill or hormone therapy. These preparations have different estrogen formulations and may have differing benefits and risks. At present, there are no robust data to inform clinical recommendations and women’s decision-making about treatment that they may be taking for many years. The POISE study (Premature Ovarian Insufficiency Study of Effectiveness of hormonal therapy) has been designed to determine whether hormone therapy is superior to combined oral contraceptives on important clinical outcomes and patient-reported symptoms, based on the hypothesis that hormone therapy provides more physiological continuous hormone supplementation with natural estrogens. The study is an open and pragmatic, parallel, randomized controlled trial. The primary outcome is absolute bone mineral density assessed by dual-energy X-ray absorptiometry of the lumbar spine after 2 years of treatment. The study will also investigate cardiovascular markers, symptom relief and acceptability of treatment, and will continue to collect long-term data on fractures and cardiovascular events. Results will inform future guidance on management of POI

    Dendritic transport. I. Colchicine stimulates the transport of lysosomal enzymes from cell bodies to dendrites.

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    Injection of colchicine into the lateral cerebral ventricle of the rat was found to induce a paradoxical translocation of two lysosomal enzymes, dipeptidyl peptidase II (Dpp II) and acid phosphatase, from the soma of neurons to the dendrites. Following a single injection of colchicine, neuronal somata, which normally contain the bulk of these lysosomal enzymatic activities, become depleted of these enzymes, whereas dendrites become abnormally enriched. All neurons which contained these enzymes, except those of the mesencephalic nucleus of the trigeminal nerve, displayed this phenomenon. Lysosomal enzyme translocation into dendrites was observed in the mitral cell layer within 1 hr after a colchicine injection and could be induced in most neuronal populations by injections of colchicine as low as 25 micrograms. Five days after a 100-micrograms colchicine injection, a normal pattern of enzyme distribution was observed, indicating that the effect of colchicine was reversible. Enzyme translocation was not accompanied by gross changes in cell morphology, nor did it result in the specific loss of neuronal cell bodies which contained these enzymes. The results indicate that colchicine, under conditions known to inhibit axoplasmic transport, stimulates the transport of lysosomal enzymes from the cell body to the dendrites

    Challenges of E-Waste pollution to soil environments in Nigeria - A Review

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    Hitherto Nigeria has been identified as a major dumping ground for e-waste from developed countries of the world arising from increasing demand for information computer technology (ITC) and other electronic gadgets by the populace especially with the relation of telecom sector since 2001. The term “e-waste” may be applied to electrical and electronic waste material of all  categories and includes but not limited to computers, refrigerators, television sets, mobile phones, office electronic devices, entertainment device electronics and electronic toys. Evidently, in addition to human health issues associated with e-waste management, e-waste constitutes a challenge to both developed and developing countries though markedly pronounced in the latter because of the dearth of appropriate technology in handling the menace posed by the discarded waste materials. There is paucity of information in quantitative terms regarding the effect of ewaste on the environment (including the soil fauna and flora) especially in Nigeria. However, e-waste has been implicated as being deleterious to soil quality, soil fauna and flora especially from studies outside Nigeria. In this paper this category of wastes will be assessed and in relation to its possible influence on soil environment in forms including heavy metal pollution. Possible e-waste management strategies will also be highlighted on soil environment with particular reference to Nigeria.Keywords: E-waste, Pollution, Soil, Environment, E-waste managemen

    Characterization traffic induced compaction in controlled traffic farming (CTF) and random traffic farming (RTF) - A multivariate approach

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    A field scale experiment was carried out in Pukekohe in 2020 under an annual grass crop season to characterize the subsoil compaction in controlled traffic farming (CTF) and random traffic farming systems (RTF). Soil penetration resistance (PR) measurements were taken in each field using a cone penetrometer fitted with a 100 mm2 60° top angle cone. Multivariate analysis was performed to identify penetration resistance by depth through cluster analysis and principal component analysis (PCA). Repeated measures ANOVA was performed on the penetration data using the mixed model procedure to determine the treatment effects. In RTF, the penetrometer values increased more rapidly with depth resulting in higher values being recorded from 20cm compared to CTF. In contrast, it was greater in CTF than in RTF at the subsurface (55-60cm). The differences in PR declined beyond 55cm depth at both sites. All depths showed that differences in soil PR were most apparent in the 5-40cm depth, with significant differences between CTF and RTF (P0.05) showing that the soil layers were homogeneous in both systems beyond 40cm depth. The propagation of subsurface compaction was identified at the deeper layer (40-60cm) in CTF systems whereas it was identified from shallower depths (25-55cm) in RTF system

    Rab8 binding to immune cell-specific adaptor LAX facilitates formation of trans-Golgi network-proximal CTLA-4 vesicles for surface expression.

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    Despite playing a central role in tolerance, little is known regarding the mechanism by which intracellular CTLA-4 is shuttled from the trans-Golgi network to the surfaces of T cells. In this context, Ras-related GTPase Rab8 plays an important role in the intracellular transport, while we have previously shown that CTLA-4 binds to the immune cell adaptor TRIM in T cells. In this study, we demonstrate that CTLA-4 forms a multimeric complex comprised of TRIM and related LAX that in turn binds to GTP bound Rab8 for post-Golgi transport to the cell surface. LAX bound via its N terminus to active GTP-Rab8, as well as the cytoplasmic tail of CTLA-4. TRIM required LAX for binding to Rab8 in a complex. Wild-type LAX or its N terminus (residues 1 to 77) increased CTLA-4 surface expression, whereas small interfering RNAs of Rab8 or LAX or disruption of LAX/Rab8 binding reduced numbers of CTLA-4-containing vesicles and its coreceptor surface expression. LAX also promoted the polarization of CTLA-4 and the reorientation of the microtubule-organizing center to the site of T-cell receptor engagement. Our results identify a novel CTLA-4/TRIM/LAX/Rab8 effector complex in the transport of CTLA-4 to the surfaces of T cells

    Chronically shortened rod outer segments accompany photoreceptor cell death in Choroideremia

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    X-linked choroideremia (CHM) is a disease characterized by gradual retinal degeneration caused by loss of the Rab Escort Protein, REP1. Despite partial compensation by REP2 the disease is characterized by prenylation defects in multiple members of the Rab protein family that are master regulators of membrane traffic. Remarkably, the eye is the only organ affected in CHM patients, possibly because of the huge membrane traffic burden of the post mitotic photoreceptors, which synthesise outer segments, and the adjacent retinal pigment epithelium that degrades the spent portions each day. In this study, we aimed to identify defects in membrane traffic that might lead to photoreceptor cell death in CHM. In a heterozygous null female mouse model of CHM (Chmnull/WT), degeneration of the photoreceptor layer was clearly evident from increased numbers of TUNEL positive cells compared to age matched controls, small numbers of cells exhibiting signs of mitochondrial stress and greatly increased microglial infiltration. However, most rod photoreceptors exhibited remarkably normal morphology with well-formed outer segments and no discernible accumulation of transport vesicles in the inner segment. The major evidence of membrane trafficking defects was a shortening of rod outer segments that was evident at 2 months of age but remained constant over the period during which the cells die. A decrease in rhodopsin density found in the outer segment may underlie the outer segment shortening but does not lead to rhodopsin accumulation in the inner segment. Our data argue against defects in rhodopsin transport or outer segment renewal as triggers of cell death in CHM

    HH-IPG: Leveraging Inter-Packet Gap Metrics in P4 Hardware for Heavy Hitter Detection

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    The research community has recently proposed several solutions based on modern programmable switches to detect entirely in the data plane the flows exceeding pre-determined thra eshold in a time window, i.e., Heavy Hitters (HH). This is commonly achieved by dividing the network stream into fixed time slots and identifying each separately without considering the traffic trends from previous intervals. In this work, we show that using specified time windows can lead to high inaccuracies. We make a case for rethinking how switches analyze the incoming packets and propose to leverage per-flow Inter Packet Gap (IPG) analytics instead of using flow counters for HH detection. We propose an algorithm and present a P4 pipeline design using this new metric in mind. We implement our solution on P4 hardware and experimentally evaluate it against real traffic traces. We show that our results are more accurate than related work by up to 20% while reducing the control channel overhead by up to two orders of magnitude. Finally, we showcase a QoS-oriented application of the proposed dataplane-only IPG-based HH detection in a mobile network scenario
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