Floral syndrome and breeding system of Senna (Cassia) corymbosa

Senna (Cassia) corymbosa is an ornamental plant with asymmetric flower in which petals and stamens are also involved in floral asymmetry. The pollen number of abaxial lateral stamen (AL), abaxial median stamen (AM) and middle stamen (MI) are descended in sequence. In field, the insects of visiting flowers are available and pollinators are essential to the pollination success of S. corymbosa. Bombidae was presumably the effective pollinators by buzzing pollination and wasp may be the potential pollinators. Pollen number and germination rate per type of stamen experiments supported the hypothesis of “division-of-labour” among stamens by Darwin. Both AL, AM and MI may afford food to visiting insects, while long stamens (including AL and AM) function as the “pollinating” stamens and the brownish yellow is presumably the effective color attractants to pollinators.Key words: Senna, pollen, pollination, breeding system

Modelling Effluent Assimilative Capacity of Ikpoba River, Benin City, Nigeria

The sheer display of reprehensible propensity on the part of public hospitals, abattoirs, breweries and city dwellers  at large to discharge untreated waste, debris, scum and, in particular, municipal and industrial effluents into Ikpoba River has morphed into a situation whereby the assimilative capacity of the river has reached a record level. The seeming quietism and clinical posture of the relevant Environmental Agency to this pathological condition is sickening and in any case seen as remiss on their part. This paper seeks to determine the assimilative capacity of the river with a view to articulating policy-proposal stream in the instance that its value is unsafe for ichthyofaunal beings and humans.  A combination of basic Streeter-Phelp equation and monograph of Fair et al. were used for the determination of the assimilative capacity and the maximum allowable biological oxygen demand (BOD) load discharged into the river from three identified point sources of wastewater and for three different seasons in Nigeria (i.e. rainy, dry and harmattan seasons). Results indicate that in all the segments studied, the Fair ratio (self-purification factor) is less than unity, indicating the predominance of deoxygenation rate over reaeration rate. Reaeration rate ranges over all real values from 0.641day-1to 0.693day-1, while deoxygenation rate ranges between 0.718 day-1 and 0.839 day-1; a condition which indicates a poor assimilative capacity potential. Moreover, a higher assimilative capacity was obtained for rainy season for all the segments studied, with sampling point 3 (Guinness-harmattan and dry season) showing an overall worse assimilative capacity and poor maximum allowable BOD of 8.1x109, 1.28x1010 and 5.60x109 kg/day respectively. In a way, the determination of the assimilative capacity of Ikpoba River is a landmark in the history of the river pollution. It beggars belief that we live down the harrowing pathological condition of the river without recognizing its wider implications.http://dx.doi.org/10.4314/njt.v34i1.1

EUDIOMETRIC THEORETIC-APPROACH TO MODELLING THE ASSIMILATIVE CAPACITY OF A RIVER: INCORPORATION OF BOOTSTRAPPING NEEDFUL FOR SENSITIVITY ANALYSIS

The mathematical physics underlying the adsorption and subsequent desorption of dissolved oxygen (DO) in a water body subject to effluent loading had been rarely investigated. The current state of play in this field although reflects use of different analysis, the combine use of hat matrix and bootstrapping techniques to study the phenomenon of chemical adsorption and desorption of DO at molecular level in a polluted waterbody has not been thoroughly investigated. This study seeks to use a matrix projector, H-hat (Ĥ), to cast virtual spectral rays on pollutant loadings in a water body and in the process unravel the dynamics of chemical and biological gravitation of dissolved oxygen towards constituents of effluent pollutants in water body. This approach is anchored on the ordinary least squares methodology of multivariate linear regression. The method hypothecated is studded by a mathematical physics analysis of the phenomenon. Bootstrapping was used to establish means and variances of regression parameters, and subsequently, the confidence intervals of point estimates of parameters. Tricking technique adopted facilitated the development of extreme values of the dissolved oxygen and hence the supremum and infimum of assimilative capacity of the river which fluctuates with intensity of effluent loadings and season of the year (rainy, dry, and harmattan seasons). The result of bootstrapping revealed that assimilative capacity fluctuated widely from the values detected by point estimates of regression parameters thus suggesting that tricking of regression parameters, in turn, tunes up the regression model, and hence, fine tunes the value of assimilative capacity through necessary adjustments of model parameters. The results of this study obviates the need to deploy eudiometer for laborious direct measurement of dissolved oxygen in a body of polluted water. Thus an elegant technique for crossing the stream where it is shallowest has been developed in this study. The method is considered as a great improvement on previous approaches that seem to dawdle. http://dx.doi.org/10.4314/njt.v35i1.2

Influence of Effluent Discharge and Runoffs into Ikpoba River on its Water Quality

Unfettered effluent discharge, in addition to seasonal runoffs, into Ikpoba River, have been blamed for the ever poor water quality noticed in the river. This study seeks to investigate the role of industrialization and/ or urbanization on the degraded water quality of the river. Chemical analyses of samples of the river water collected at predetermined sampling points were undertaken and the observations obtained were subjected to ANOVA, correlation, and eigenvalue analysis. Results obtained showed that each point source has its relative contribution to the overall degradation of the river water quality. In merit order, the eigenvalue analyses carried out suggests that phosphate, nitrate, cadmium, copper, iron, lead and turbidity are the most offensive factors showing values of 0.868, 0.933, 0.770, 0.503, 5.063, 0.717, 30mg/L respectively. Remarkably, surface runoffs from municipal drains channelled to stations 1 and 2 contribute significantly to the turbidity with 4.333 and 4.233mg/L respectively, whereupon urbanization and industrialization are seemingly the culprits

Birth weight and risk of ischemic heart disease: A Mendelian randomization study

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Liver Enzymes and Risk of Ischemic Heart Disease and Type 2 Diabetes Mellitus: A Mendelian Randomization Study

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Interleukin-2 Confers Cardioprotection by Inhibiting Mitochondrial Permeability Transition Pore

In the present study, we determined whether interleukin-2 (IL-2) confers cardioprotection by inhibiting mitochondria permeability transition pore (MPTP) opening. In isolated rat hearts subject to 30 min ischemia and 120 min reperfusion (IR), IL-2 (50 U/ml) decreased the infarct size and LDH release, effects blocked by a selective kappa-opioid receptor antagonist, Nor-BNI (5 microM) or an opener of MPTP, atractyloside (Atr, 20 microM). In isolated ventricular myocytes subjected to anoxia and reoxygenation (AR), which reduced both the amplitude of the electrically induced [Ca2+]i transient and diastolic [Ca2+]i, IL-2 attenuated the AR-induced alterations and their effects were abolished by Atr. In addition, IL-2 attenuated the reduction in calcein fluorescence in myocytes subject to AR and reduced calcium-induced swelling in mitochondria of rat hearts subjected to IR, which were similar to effect of inhibitor of MPTP. The observations indicated that IL-2 confers cardioprotection by inhibiting the MPTP opening.published_or_final_versio

Experimental investigation of multi-step stress-relaxation-ageing of 7050 aluminium alloy for different pre-strained conditions

A novel insight into the whole two-step stress relaxation ageing process during T74 multi–step ageing treatment (120 °C for 6 h and subsequently 177 °C for 7 h), which is typically experienced by extra-large aircraft components that contain high residual stresses, has been established. Stress relaxation ageing (SRA) tests, tensile tests and transmission electron microscopy (TEM) were performed on AA7050 samples to determine the relationship between internal microstructure and macroscopic behaviour during the stress relaxation and precipitate evolution process. Samples were subjected to SRA at different initial stresses (220–360 MPa) after being pre-strained to different extents (i.e. 0%, 1%, 3%). Room temperature tensile tests were then performed on interrupted SRA test specimens to examine the corresponding strengthening phenomenon. TEM was performed on a selection of peak–aged and T74 over–aged samples to study the precipitate distribution. At 120 °C typical stress relaxation behaviour was observed and the data follow ed a logarithmic curve. Subsequently at 177 °C, dislocation–creep dominated stress relaxation behaviour, with no apparent threshold stress, was observed. The absence of a threshold stress at 177 °C may be attributed to the continuous over-ageing phenomenon. The effect of pre-deformation levels and initial stresses on SRA has also been investigated. Pre-stretching, which creates uniformly distributed dislocations, promotes stress relaxation and ageing. No significant influence of initial stress level on SRA was observed at 120 °C, but noticeable effects were seen at 177 °C. The calculated stress exponent n at 177 °C is found independent of the initial stresses. These findings provide clear scientific guidance for residual stress reduction during the multi-step ageing process of AA7050 and provide the basis for residual stress prediction models

Finding optimal threshold for correction error reads in DNA assembling

Background: DNA assembling is the problem of determining the nucleotide sequence of a genome from its substrings, called reads. In the experiments, there may be some errors on the reads which affect the performance of the DNA assembly algorithms. Existing algorithms, e.g. ECINDEL and SRCorr, correct the error reads by considering the number of times each length-k substring of the reads appear in the input. They treat those length-k substrings appear at least M times as correct substring and correct the error reads based on these substrings. However, since the threshold M is chosen without any solid theoretical analysis, these algorithms cannot guarantee their performances on error correction. Results: In this paper, we propose a method to calculate the probabilities of false positive and false negative when determining whether a length-k substring is correct using threshold M. Based on this optimal threshold M that minimizes the total errors (false positives and false negatives). Experimental results on both real data and simulated data showed that our calculation is correct and we can reduce the total error substrings by 77.6% and 65.1% when compared to ECINDEL and SRCorr respectively. Conclusion: We introduced a method to calculate the probability of false positives and false negatives of the length-k substring using different thresholds. Based on this calculation, we found the optimal threshold to minimize the total error of false positive plus false negative. © 2009 Chin et al; licensee BioMed Central Ltd.published_or_final_versio