957 research outputs found

    Status of Indigenous Tree Species in Girei Forest Reserve of Adamawa State

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    Quantitative assessment of indigenous tree species was carried out in Girei Forest Reserve. To achieve the objectives, five plots of 50m x 50m in size were randomly laid in the reserve and number of trees in each plot was enumerated. The highest frequency of 26.7% was observed in the second plots, while the fourth plot exhibit a lower frequency of 15.0%. The result also revealed that almost 53.3% of the tree species in the reserve are being endangered (tree with frequency less than 5). It was observed that most of the indigenous trees are rare in the area and this could be as a result of the following agents such as bush burning, animal grazers, farmers and saw millers. The results of Shannon and Evenness Indices indicated the high uncertainty and rareness of the indigenous species in the study area. Also, Analysis of variance result revealed that there was no significant relationship among the sampled plot (p > 0.05). At this point of endangerment of the indigenous tree species, there is therefore a need for conservation strategies for future use of these indigenous trees and to reduce the effect of global warming on the earth surface.Keywords: Quantitative assessment, Global warming, Indigenous, Conservation, Rare

    Cardiotoxicity induced by inhalation of petroleum products

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    Exposure to petroleum products has been associated with high blood pressure. This study was designed to investigate the effect of petroleum products on cardiac tissue architecture and creatine kinase (CK- MB). Forty male Sprague Dawley rats were exposed to diesel, kerosene and petrol by inhalation for eight weeks. At the end of the study, blood samples were collected, blood pressure was measured and animal heart was harvested for histological study. Blood pressure and serum creatine kinase (CK-MB) was significantly higher in the exposed compared with control rats. Degeneration of myocardial tissue was also observed in the exposed rats. The findings from the study revealed that the cardio-toxic effect of petroleum products is via creatine kinase-dependent mechanism.Keywords: Creatine kinase, phosphokinase, petroleum, heart, cardio-toxicity, blood pressur

    Cardio-metabolic risk factors and metabolic syndrome: A study of the prevalence and level of awareness of related risk factors among school teachers in Ogbomoso, South West Nigeria

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    Background: The overall health of school teachers is closely related to the performance of children in school and life generally. Objectives: This study aimed to describe the prevalence of cardiovascular risk factors and metabolic syndrome among school teachers in Ogbomoso, Nigeria. Methods: Two hundred secondary school teachers were randomly selected from all the secondary schools in the two local Governments in Ogbomoso, Nigeria. Relevant laboratory investigations and electrocardiography were performed. Metabolic syndrome was defined using the Joint Scientific Statement on Harmonising the Metabolic Syndrome Criteria. Results: Metabolic syndrome (MS) was identified among 44(22.0%) of study participants. It was more common among females 33(28.2%) compared to males 11(13.3%) [p = 0.002]. The prevalence of some cardiovascular risk factors were as follows: visceral obesity 108(54.0%), low HDL 105(52.5%), hypertension 58 (29.0%), BP > 130/85 mmHg, 76(38.0%), impaired fasting blood glucose 49(24.5%) and hypertriglyceridaemia 14(7.0%). Only a small fraction (39; 19.5%) demonstrated good level of knowledge about the cardiovascular risk factors. Conclusion: Cardiovascular risk factors were common among school teachers in Ogbomoso, south-west Nigeria in addition to a low level of awareness and poor control of the risk factors

    Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

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    The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

    Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

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    The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

    X-ray emission from the Sombrero galaxy: discrete sources

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    We present a study of discrete X-ray sources in and around the bulge-dominated, massive Sa galaxy, Sombrero (M104), based on new and archival Chandra observations with a total exposure of ~200 ks. With a detection limit of L_X = 1E37 erg/s and a field of view covering a galactocentric radius of ~30 kpc (11.5 arcminute), 383 sources are detected. Cross-correlation with Spitler et al.'s catalogue of Sombrero globular clusters (GCs) identified from HST/ACS observations reveals 41 X-rays sources in GCs, presumably low-mass X-ray binaries (LMXBs). We quantify the differential luminosity functions (LFs) for both the detected GC and field LMXBs, whose power-low indices (~1.1 for the GC-LF and ~1.6 for field-LF) are consistent with previous studies for elliptical galaxies. With precise sky positions of the GCs without a detected X-ray source, we further quantify, through a fluctuation analysis, the GC LF at fainter luminosities down to 1E35 erg/s. The derived index rules out a faint-end slope flatter than 1.1 at a 2 sigma significance, contrary to recent findings in several elliptical galaxies and the bulge of M31. On the other hand, the 2-6 keV unresolved emission places a tight constraint on the field LF, implying a flattened index of ~1.0 below 1E37 erg/s. We also detect 101 sources in the halo of Sombrero. The presence of these sources cannot be interpreted as galactic LMXBs whose spatial distribution empirically follows the starlight. Their number is also higher than the expected number of cosmic AGNs (52+/-11 [1 sigma]) whose surface density is constrained by deep X-ray surveys. We suggest that either the cosmic X-ray background is unusually high in the direction of Sombrero, or a distinct population of X-ray sources is present in the halo of Sombrero.Comment: 11 figures, 5 tables, ApJ in pres

    Azimuthal anisotropy of charged particles at high transverse momenta in PbPb collisions at sqrt(s[NN]) = 2.76 TeV

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    The azimuthal anisotropy of charged particles in PbPb collisions at nucleon-nucleon center-of-mass energy of 2.76 TeV is measured with the CMS detector at the LHC over an extended transverse momentum (pt) range up to approximately 60 GeV. The data cover both the low-pt region associated with hydrodynamic flow phenomena and the high-pt region where the anisotropies may reflect the path-length dependence of parton energy loss in the created medium. The anisotropy parameter (v2) of the particles is extracted by correlating charged tracks with respect to the event-plane reconstructed by using the energy deposited in forward-angle calorimeters. For the six bins of collision centrality studied, spanning the range of 0-60% most-central events, the observed v2 values are found to first increase with pt, reaching a maximum around pt = 3 GeV, and then to gradually decrease to almost zero, with the decline persisting up to at least pt = 40 GeV over the full centrality range measured.Comment: Replaced with published version. Added journal reference and DO

    Search for new physics with same-sign isolated dilepton events with jets and missing transverse energy

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    A search for new physics is performed in events with two same-sign isolated leptons, hadronic jets, and missing transverse energy in the final state. The analysis is based on a data sample corresponding to an integrated luminosity of 4.98 inverse femtobarns produced in pp collisions at a center-of-mass energy of 7 TeV collected by the CMS experiment at the LHC. This constitutes a factor of 140 increase in integrated luminosity over previously published results. The observed yields agree with the standard model predictions and thus no evidence for new physics is found. The observations are used to set upper limits on possible new physics contributions and to constrain supersymmetric models. To facilitate the interpretation of the data in a broader range of new physics scenarios, information on the event selection, detector response, and efficiencies is provided.Comment: Published in Physical Review Letter

    Compressed representation of a partially defined integer function over multiple arguments

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    In OLAP (OnLine Analitical Processing) data are analysed in an n-dimensional cube. The cube may be represented as a partially defined function over n arguments. Considering that often the function is not defined everywhere, we ask: is there a known way of representing the function or the points in which it is defined, in a more compact manner than the trivial one
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