Average Standard Error Research Articles

Improved bromide measurements using chloramine-T shows, bromide depletion in the Gulf of Maine

The assay for bromide (Br−) based on bromination of phenol red using chloramine-T was tested with small volumes (0.3 ml or less) of seawater and had two confounding issues. High blanks (with no added bromide) occasionally occurred, and the reaction-derived color frequently was destroyed by coupled reactions within the assay. The method was modified by lowering the assay pH to 3.9, by reducing the assay temperature to 13C, and by keeping the reaction short (10 s). As a result, blank absorbances were very low, and reaction-produced color was not destroyed in routine assays. In addition, no interferences by ionic seawater constituents were found. The assay was tested on natural water samples from the Antarctic continental shelf and from the Gulf of Maine. The results were highly precise; duplicates of 32 samples from the Gulf of Maine had an average standard error of the mean of ± 2.26 μmol kg−1. Antarctic bottom waters had bromide concentrations of 834.1 and 831.9 μmol kg−1 and the Br−/Chl ratio, where Chl is the chlorinity in μmol chloride equivalents (kg of seawater)−1, statistically matched the previously determined ocean mean of 0.15410 mol %. In the Gulf of Maine, vertical profiles from the sea surface to the sea floor showed lower concentrations inshore near the surface (minimum of 762.2 μmol kg−1) and greater concentrations at depth (maximum of 837.3 μmol kg−1 in a basin containing continental slope water). At the offshore basin with slope water, the Br−/Chl ratio of all waters below 15 m matched the ocean mean. Sites near the Maine and New Hampshire coast had lower concentrations of bromide, and the station-averaged Br−/Chl ratios reached a minimum of 0.15283 mol %. A previous explanation for reduced Br−/Chl ratios in shallow seas was that the fresh water Br−/Chl ratio could be much less than the ocean mean. A two end-member mixing model of the Gulf of Maine showed that this mechanism could explain a reduction in bromide concentrations in coastal Maine of about 0.6 μmol kg−1, but this depletion is 10-fold low of the observed bromide reduction. The lowered bromide content in coastal waters could be due to 1) significant macroalgal uptake along the coastline, and 2) in situ bromination of dissolved organics and planktonic detritus via photochemical or peroxide oxidation.

Application of modified tracking components in CyberKnife treatment of thoracic and abdominal tumors

Objective To improve synchrony tracking components of CyberKnife (tracking vest and tracking markers) and to analyze the clinical application value of the improved tracking components in CyberKnife treatment of thoracic and abdominal tumors. Methods The tracking apron was made of knitted four-side elastic spandex cloth and suture design of Velcro, which was used to stick the tracking markers on the chest and abdomen of patients. The tracking markers added a 2 cm thick light foam block to the bottom of the original markers, and then the hook face of the Velcro was fixed to the bottom of the light foam. The improved trace component (the improved component) and the original component (the vendor component) were applied to the lung tracking treatment model, and the manufacturer components were included in the reference group. Adoption of improved components into the observation group; 20 different types of respiratory waveforms were simulated and applied to the same mold plan. After treatment, the coverage rate, mean standard deviation, maximum standard deviation and the slope of XYZ-axis vs. R correlation graph were recorded. The relevant parameters of Synchrony model and wearable time of two components were compared, and the application significances of the improved tracking component in the breathing tracking process of the CyberKnife were evaluated. Results The maximum slope [median(interquartile range)] of XYZ-axis vs. R related graph in the reference group was 0.73 (3.89), 0.27 (0.49) and 0.34 (1.02), respectively. The maximum slope of XYZ-axis vs. R related graph in the observation group was 0.70 (2.78), 0.31 (0.30) and 0.36 (0.75), respectively. There was no statistically significant difference in the slope of XYZ-axis vs. R between the reference group and the observation group (all P > 0.05). There was no significant difference in the average standard error and maximum standard error between the reference group and the observation group [(1.7±0.4) mm vs. (1.7±0.5) mm, t=-0.382, P= 0.710; (2.0±0.6) mm vs. (1.7±0.5) mm, t=-0.877, P= 0.401], and the difference of the model coverage rate between the two groups was statistically significant [(48±18)% vs. (60±22)%, t= 2.762, P= 0.042]. The setup time of tracking components in the observation group was less than that in the reference group, and the difference was statistically significant [(44±24) s vs. (81±15) s, t=-4.310, P= 0.001]. Conclusions The improved tracking components are comparable to the manufacturer tracking components in the standard error of the Synchrony model. The improved components shorten the wear time and appropriately improve the coverage of the Synchrony model. Key words: Thoracic neoplasms; Abdominal neoplasms; CyberKnife; Stereotactic body radiation therapy; Standard error; Synchrony model

Blocking and re-arrangement of pots in greenhouse experiments: which approach is more effective?

BackgroundObservations measured in field and greenhouse experiments always contain errors. These errors can arise from measurement error, local or positional conditions of the experimental units, or from the randomization of experimental units. In statistical analysis errors can be modelled as independent effects or as spatially correlated effects with an appropriate variance–covariance structure. Using a suitable experimental design, a part of the variance can be captured through blocking of the experimental units. If experimental units (e.g. pots within a greenhouse) are mobile, they can be re-arranged during the experiment. This re-arrangement enables a separation of variation due to time-invariant position effects and variation due to the experimental units. If re-arrangement is successful, the time-invariant positional effect can average out for experimental units moved between different positions during the experiment. While re-arrangement is commonly done in greenhouse experiments, data to quantify its usefulness is limited.ResultsA uniformity greenhouse experiment with barley (Hordeum vulgare L.) to compare re-arrangement of pots with a range of designs under fixed-position arrangement showed that both methods can reduce the residual variance and the average standard error of a difference. All designs with fixed-position arrangement, which accounted for the known north–south gradient in the greenhouse, outperformed re-arrangement. An α-design with block size four performed best across seven plant growth traits.ConclusionBlocking with a fixed-position arrangement was more efficient in improving precision of greenhouse experiments than re-arrangement of pots and hence can be recommended for comparable greenhouse experiments.

Mapping the spatial variability of the field distribution of sterile Anastrepha ludens over a release area

AbstractThe sterile insect technique (SIT) is an environmental‐friendly method used against Anastrepha ludens Loew (Diptera: Tephritidae) populations. This study aimed to perform an analysis of the spatial variability of the field distribution of sterile A. ludens using a geostatistical approach along with Geographic Information Systems (GIS). Field data on captures of sterile A. ludens during a Valencia orange season over a release area were analysed using spherical, exponential and Gaussian variograms. Such variograms were evaluated by criteria such as the mean absolute error, average standard error, root mean square error and the coefficient of determination. Results revealed a spatially structured distribution of sterile A. ludens across the release area. Interpolated models by Ordinary Kriging technique exhibited continuous surfaces evidencing spatial heterogeneity of the distribution of flies. Such a result evidenced that the spatial dynamics of flies significantly varied despite the planned uniform coverage of the release. The GIS led to integrating spatial information of the spatial dynamics through one single model. The release activity should be improved westward of the studied area, as the final model suggested that the ratio sterile: wild is lower than that in the east. This study provides insights into the spatial analysis of the distribution of sterile flies further than one single geographical point. Moreover, it highlights geostatistical techniques and GIS as useful tools for the assessment of the impact and quality of the release activity over fruit‐growing areas subjected to an area‐wide integrated pest management approach.

Probability Langmuir-Hinshelwood based CO2 photoreduction kinetic models

For engineering solutions, scaling photoreactors and processes, kinetic models that describe the impact of process conditions on CO2 photoreduction are critical to driving this technology forward. Probability Langmuir-Hinshelwood based CO2 photoreduction kinetic models were developed after several criteria that included: a high purity photodifferential photoreactor with a high ratio of reagent gas volume to irradiated photocatalyst surface area and automated robust data collection and kinetic modelling using a MATLAB program. Product distribution profiles indicated the dynamic changes occurring over the photocatalyst with an initial increase in H2 product distribution, followed by an increase in CH4 and finally CO product distribution, possibly due to the photocatalytic degradation of CH2O and CH2O2 intermediates. Production of H2 increased with a decrease in CH4 when the partial pressure of H2O was increased. Using the glyoxal mechanism, this is possibly explained via the formation of CH3CO2H from H2O reacting with CH3CHO that prevents the full conversion of CH3CHO to CH4. To account for deactivation, probability Langmuir–Hinshelwood based kinetic models were used to fit CO2 photoreduction kinetic data for CH4, CO and H2 with low average standard errors of 3.44×10-4,1.54×10-4 and 1.36×10-4, respectively. The probability LH based kinetic model coefficients were estimated with low standard deviations, using a robust and repeatable numerical method using a trust-region and multi-start algorithm. The models were used to predict optimised selectivity of CH4, CO and H2.

Modelling Soft Tissue Deformation Based on Spatial Kriging

People can only obtain incomplete information when needle get into soft tissue. The actual conditions limit monitoring results. The kriging, as a statistical interpolation method, can effectively transform discrete point information into facial continuous information. On the basis of displacement data of pork soft tissue, the correlation parameter setting and optimal semi-variance model selection of kriging were studied to determine the kriging interpolation results. The results show that the accuracy of the kriging model can reach millimetre level, the maximum error is about 0.8mm, the average standard error is 0.35mm, and the calculation is simple. It can help doctors provide references when the soft tissue cannot be directly observed, and predict the deformation within the soft tissue.

A parametric study for in-pile use of the thermal conductivity needle probe using a transient, multilayered analytical model

By utilizing an in-pile measurement, thermal conductivity can be determined under prototypic conditions over a range of burnup. In this work we develop a multilayer quadrupoles analytical model to describe the transient thermal interactions between a line heat source (i.e. needle probe) and cylindrical nuclear fuel geometry for in-pile thermal conductivity measurements. A finite element analysis of the detailed needle probe geometry was compared to results from the analytical model to verify the assumptions made in the analytical model. Experimentally, the needle probe was used to measure the thermal properties of polytetrafluoroethylene (PTFE) and stainless steel 304 with three different diameters (10 mm, 20 mm, and 30 mm). The analytical model was compared to the experimental measurements, which showed good agreement within an average standard error of 0.501 K. Rather than be restricted to the linear region of the temperature v. log(time) slope, the analytical model can use the entire experimental curve to determine the thermal conductivity of the samples. Using the analytical model, a parameter and sensitivity study was conducted to explore the viability of accurately measuring the sample thermal conductivity under various measurement conditions. In addition, three different parameters were studied for optimization: various UO2 diameters, various probe diameters, and thermal contact resistance. The validated model and results provide the foundation to elucidate a better understanding of in-pile thermal conductivity measurements and informs future needle probe designs to measure samples with diameters as low as 10 mm.

Hybrid LEAP modeling method for long-term energy demand forecasting of regions with limited statistical data

An accurate long-term energy demand forecasting is essential for energy planning and policy making. However, due to the immature energy data collecting and statistical methods, the available data are usually limited in many regions. In this paper, on the basis of comprehensive literature review, we proposed a hybrid model based on the long-range alternative energy planning (LEAP) model to improve the accuracy of energy demand forecasting in these regions. By taking Hunan province, China as a typical case, the proposed hybrid model was applied to estimating the possible future energy demand and energy-saving potentials in different sectors. The structure of LEAP model was estimated by Sankey energy flow, and Leslie matrix and autoregressive integrated moving average (ARIMA) models were used to predict the population, industrial structure and transportation turnover, respectively. Monte-Carlo method was employed to evaluate the uncertainty of forecasted results. The results showed that the hybrid model combined with scenario analysis provided a relatively accurate forecast for the long-term energy demand in regions with limited statistical data, and the average standard error of probabilistic distribution in 2030 energy demand was as low as 0.15. The prediction results could provide supportive references to identify energy-saving potentials and energy development pathways.

A simple method for computing sprint acceleration kinetics from running velocity data: Replication study with improved design

Measuring the ground reaction forces (GRF) underlying sprint acceleration is important to understanding the performance of such a common task. Until recently direct measurements of GRF during sprinting were limited to a few steps per trial, but a simple method (SM) was developed to estimate GRF across an entire acceleration. The SM utilizes displacement- or velocity-time data and basic computations applied to the runner’s center of mass and was validated against compiled force plate (FP) measurements; however, this validation used multiple-trials to generate a single acceleration profile, and consequently fatigue and error may have introduced noise into the analyses. In this study, we replicated the original validation by comparing the main sprint kinetics and force-velocity-power variables (e.g. GRF and its horizontal and vertical components, mechanical power output, ratio of horizontal component to resultant GRF) between synchronized FP data from a single sprinting acceleration and SM data derived from running velocity measured with a 100 Hz laser. These analyses were made possible thanks to a newly developed 50-m FP system providing seamless GRF data during a single sprint acceleration. Sixteen trained male sprinters performed two all-out 60-m sprints. We observed good agreement between the two methods for kinetic variables (e.g. grand average bias of 4.71%, range 0.696 ± 0.540–8.26 ± 5.51%), and high inter-trial reliability (grand average standard error of measurement of 2.50% for FP and 2.36% for the SM). This replication study clearly shows that when implemented correctly, this method accurately estimates sprint acceleration kinetics.

The Influence of Project Based Learning based on Process Skills Approach to Student’s Creative Thinking Skill

This study aims to examine the effect of Project Based Learning (PjBL) based on a process skills approach to students’ creative thinking skills. This study uses a one-shot case study design. Research subjects were students of class X SMA N 1 Kalasan, Sleman with a total of 48 students. The selection of research subjects was done by simple random sampling. Data is collected from the results of the work done by students. Data analysis was carried out by descriptive analysis and inferential analysis. The results of the descriptive analysis presented are the average value, standard error, standard deviation, minimum value, maximum value, and percentage of the achievement of each indicator of creative thinking skills. Descriptive analysis on the influence of creative thinking skills is done by analyzing each indicator on the ability to think creatively. The results obtained from the descriptive analysis showed that the achievement values on the indicators of Flexibility, Fluency, Elaboration and Originality showed the results of 31%, 26%, 24% and 19% respectively. In inferential analysis is done by analyzing normality and hypothesis testing with one sample t-test. In the normality test obtained by result of Ho which shows that there is influence of creative thinking skills after using learning with the PjBL model based on process skills approach.

Variability of outcrop magnetic susceptibility and its relationship to the porphyry Cu centers in the Highland Valley Copper district

The Highland Valley Copper porphyry Cu-(Mo) centers compose Canada’s largest porphyry Cu mining district, and are hosted in plutonic rocks of the Late Triassic Guichon Creek batholith in the Quesnel terrane, British Columbia. Here we evaluate the relationship between variations in magnetic susceptibility and alteration in order to define a footprint around the porphyry Cu centers using a district-scale dataset of 1610 minimally weathered outcrops and 11,432 magnetic susceptibility measurements. Statistical analysis of the outcrop-based measurements revealed changes in outcrop geometric mean magnetic susceptibility and the coefficient of variation (extent of variability in relation to the mean) are proportional to vein frequency and altered rock volume estimates. At a confidence interval of 95% and 9 degrees of freedom, the average standard error (uncertainty) of the geometric mean and coefficient of variation from 10 magnetic susceptibility outcrop measurements is 7.3% and 13.2%, respectively. Modeling of outcrop magnetic susceptibility data shows that domains of coefficient of variation of >0.3 extend 1–4 km away from the porphyry centers, whereas pronounced susceptibility lows of <10 × 10−3 SI have a smaller footprint centered on the Cu-mineralization. The magnitude of change of magnetic susceptibility coefficient of variation between protolith and altered rocks in the porphyry Cu footprint is greater than the corresponding change in susceptibility geometric means. Thus, with some caveats, variability in magnetic susceptibility provides a good signal that corresponds to vein and alteration intensity, and can potentially be used to map ore-forming processes and to vector to porphyry Cu centers.

An efficient procedure in quantitative analysis using laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy has become a general-purpose technique, and internal standard calibration is a common method for quantitative analysis. Calibration models should be reconstructed for different systems and application environments. This study presents an efficient procedure in the construction and selection of calibration models for LIBS analysis. The procedure concludes data preprocess, calibration model construction, and concentration calculation. These steps can be programmed without manual intervention. Results of the quantitative analysis of Ni-based alloys using the proposed procedure are presented in this study. Ten elements are calibrated, and most have an average relative standard error of less than 10%. The proposed procedure is an effective process for constructing and selecting calibration models.

102 Sperm cryopreservation with a soy lecithin-based medium in black-footed cats (Felis nigripes) and sand cats (Felis margarita)

Felid semen has historically been frozen using an egg yolk-based cryopreservation medium (TEY). However, the use of egg introduces several potential concerns, such as variability in composition, microbial contamination, and regulatory issues. Our recent research has focused on developing an animal protein-free medium containing soy lecithin (SOY). Our studies revealed that SOY was superior to TEY for freezing domestic cat sperm and provided similar results for freezing ocelot, Pallas’ cat, and fishing cat sperm. The objective of this study was to compare SOY to the standard TEY for sperm cryopreservation in 2 wild cat species: the black-footed cat and sand cat. Semen was collected from adult male cats (n=6/species) via electroejaculation, split into 2 aliquots, centrifuged, resuspended in either SOY or TEY, slow-cooled, and frozen in straws over nitrogen vapor. Sperm motility [percent progressively motile (PPM); rate of progressive motility on 0-5 scale (RPM)] was evaluated at 0, 1, 3, 6, and 24h post-thaw and acrosome status (AC) was assessed at 0 and 6h post-thaw. Heterologous IVF was performed using oocytes collected laparoscopically from gonadotropin-treated domestic cats. At 48h post-insemination, Hoechst33342 staining was used to determine oocyte stage, number of blastomeres, and number of accessory sperm (AS) bound to the zona pellucida of embryos and mature oocytes. Percent progressively motile, RPM, and AC were analysed with repeated-measures ANOVA; embryo cleavage, blastomere number, and AS number were analysed with one-way ANOVA. All data are reported as least squares means±average standard error. In the black-footed cat, PPM, RPM, and AC of SOY-treated sperm (32.5±4.0% motile, 2.8±0.2 RPM, 41.8±4.1% intact; 0h) did not differ from TEY-treated sperm (44.2±4.0% motile, 2.8±0.2 RPM, 46.8±4.1% intact; 0h) at any post-thaw time point (P &amp;gt; 0.05). Similarly, in the sand cat, post-thaw PPM, RPM, and AC of SOY-treated sperm (36.7±5.2% motile, 2.6±0.2 progression, 53.3±5.8% intact; 0h) did not differ from TEY-treated sperm (45.8±5.2% motile, 2.8±0.2 RPM, 51.0±5.8% intact; 0h) at any time point (P &amp;gt; 0.05). In black-footed cats, neither embryo cleavage (34.1±10.9% SOY; 58.5±10.9% TEY), blastomere number (7.8±0.8 SOY; 6.3±0.8 TEY), nor AS (3.5±0.8 SOY; 1.7±0.8 TEY) differed between treatments (P &amp;gt; 0.05). Sand cat results were similar, with no difference between SOY and TEY for cleavage (44.7±10.8% SOY; 40.6±10.8% TEY) or blastomere number (7.4±2.0 SOY; 6.7±2.0 TEY) (P &amp;gt; 0.05), but AS was higher in SOY-treated sperm (4.3±0.2 SOY; 3.5±0.2 TEY, P=0.0183). These data collectively demonstrate that our SOY medium was an effective substitute to TEY for sperm cryopreservation in the black-footed cat and sand cat. The replacement of an egg yolk-based cryomedium with a chemically defined, animal protein-free alternative represents a significant advance in quality control and biosecurity for felid semen banking and should augment the use of assisted reproduction for population management of imperiled cats. Funded by the Institute of Museum and Library Services.

Consumer Expenditures and Savings in High Income Households

Abstract A review of the existing academic literature as well as available government publications reveals a lack of information regarding expenditure behavior of high income households. In this paper, we combine multiple years of Consumer Expenditure Survey Public Use Microdata provided by the Bureau of Labor Statistics (BLS) and compute average expenditures and standard errors. We apply the same methodology used by the BLS to estimate the average expenditures by household income and household size for households with income of $70,000 and higher. The resultant tables provide details on consumption and saving patterns for higher income groups that are unavailable in the tables published by the BLS. Our tables can be utilized by forensic economists in practice for the determination of consumption and savings values in wrongful death matters in high income households.

MAPPING AND MODELLING ABOVEGROUND WOODY BIOMASS AND CARBON STOCK IN SAL (SHOREA ROBUSTA GAERTN. F.) FORESTS OF DOON VALLEY USING GEOSPATIAL TECHNIQUES

Abstract. Information on the quantitative and qualitative distribution of forest biomass is helpful for effective forest management. Besides its quantitative use, Biomass plays a twin role by acting as a carbon source and sinks but its long-term carbon-storing ability is of considerable importance which is helpful in lessening global warming and climate change impacts. The present study was done for mapping aboveground woody biomass (Bole) (AGWB) of Shorea robusta (Gaertn.f.) forests in Doon valley by establishing relationships between field measured data, satellite data derived variables and geostatistical techniques. Landsat 8 Operational Land Imager (OLI) data was used in preparing the forest homogeneity map (forest type and density). 55 sampling plots of 0.1 ha were laid across the Doon Valley using stratified random sampling. Correlations were established between Landsat 8 OLI derived variables and field measured data and were evaluated. Field measured biomass has got the maximum correlation with NDVI (0.7553) and it was further used for carrying out multivariate kriging (Cok) for biomass prediction map. Prediction errors for the AGWB were lowest for exponential model with RMSE = 66.445 Mg/ha, Average Standard Error = 71.07694 Mg/ha and RMSS = 0.95097. Carbon is calculated as 47% of the biomass value.AGWB was ranged from 163.381 to 750.025 Mg/ha and Carbon from 76.789 to 352.512 Mg/ha. Cokriging was found as a better alternative as compared to direct radiometric relationships for the spatial distribution of the AGWB of Shorea robusta (Gaertn.f.) forests and this study would be helpful in better forest management planning and research purposes.

Antidepressant activity of 4-amino-5-(alkyl-, aryl-, heteryl)-1,2,4-triazole-3-thione benzylidene derivatives

The current market for antidepressants has a number of limitations, they have a high probability of development of adverse reactions, have low latitude and stability of the therapeutic effect, and also have a long latent period of action. Therefore, it seems obvious that there is a need to create new drugs that improve the quality of life, affect the mood and are safe. An analysis of literary sources has shown that derivatives of 1,2,4-triazole have a pronounced antidepressant effect and drugs such as Trazodone and Alprozalam are widely used in medical practice. The purpose of this work was to study antidepressant effects of 1,2,4-triazole derivatives and to make analysis of the dependence between chemical structure and pharmacological activity. Materials and methods. The search of antidepressants in the series of 1,2,4-triazole derivatives was performed on the basis of the classical model of R.D. Porsolt in the modification of E.V. Schetynin. Each animal was immersed for 6 minutes in a vessel filled with water at a temperature of 27 °C. The duration of active swimming was fixed (vigorous movements of all paws with active movement), passive swimming (weak bends of the paws necessary to support the body to swim) and immobilization (no swimming motions). In addition, the number of active swimming periods of different lengths and the number of very short immobilization periods of up to 6 seconds were counted. The index of depression (ID) was calculated due to the ratio of the very short periods number of immobilization to the total number of active swimming periods. The research results are processed by modern statistical methods of analysis using personal computer, including the standard program package Microsoft Office 2013 (Microsoft Excel) and Statistica ® for Windows 6.0. The average arithmetic mean (M) and standard mean errors (±m) were calculated. The statistical significance of intergroup differences according to the experimental data was established using Student's t-criterion. To study the dependence of the influence of benzylidene derivatives of 4-amino-5-(alkyl-, aryl-, heteryl)-2,4-dihydro-3H-1,2,4-triazole-3-thione on the duration of passive swimming and the duration of immobilization was carried out by correlation analysis. Results. Benzylidene derivatives of 4-amino-5-(alkyl-, aryl-, heteryl)-1,2,4-triazole-3-thione were used as test substances. The index of depression in the use of fluoxetine decreased to 70.92 % (P < 0.05), and with the use of trazodone to 76.95 % (P < 0.05). Compounds 26 and 32 statistically significantly lowered the index of depression to 86.66 and 81.24 %, respectively, which was higher than the activity of the used comparison drugs. The main indicator of rats despair was the duration of immobilization, decreased to 73.53 % (P < 0.05) and trazodone to 79.55 (P < 0.05) when administered with fluoxetine. When applying 1,2,4-triazole derivatives, the duration of immobilization of compound 32 was reduced to 89.53 % (P < 0.05), and compounds 23 to 87.05 % (P < 0.05). Conclusions. The most active compound according to the results of the study was compound 32, which reduced the average duration of immobilization in the experimental group to 89.53 % and had a rather low index of depression (0.34 ± 0.08, P < 0.05).

Assessment of Rheological and Piezoresistive Properties of Graphene based Cement Composites

The concrete production processes including materials mixing, pumping, transportation, injection, pouring, moulding and compaction, are dependent on the rheological properties. Hence, in this research, the rheological properties of fresh cement paste with different content of graphene (0.03, 0.05 and 0.10% by weight of cement) were investigated. The parameters considered were test geometries (concentric cylinders and parallel plates), shear rate range (300–0.6, 200–0.6 and 100–0.6 s−1), resting time (0, 30 and 60 min) and superplasticizer dosage (0 and 0.1% by weight of cement). Four rheological prediction models such as Modified Bingham, Herschel–Bulkley, Bingham model and Casson model were chosen for the estimation of the yield stress, plastic viscosity and trend of the flow curves. The effectiveness of these rheological models in predicting the flow properties of cement paste was verified by considering the standard error method. Test results showed that the yield stress and the plastic viscosity increased with the increase in graphene content and resting time while the yield stress and the plastic viscosity decreased with the increase in the dosage of superplasticizer. At higher shear rate range, the yield stress increased while the plastic viscosities decreased. The Herschel–Bulkley model with the lowest average standard error and standard deviation value was found to best fit the experimental data, whereas, Casson model was found to be the most unfitted model. Graphene reduces the flow diameter and electrical resistivity up to 9.3 and 67.8% and enhances load carrying capacity and strain up to 16.7 and 70.1% of the composite specimen as compared with plain cement specimen. Moreover, it opened a new dimension for graphene-cement composite as smart sensing building construction material.

Demirjian Stage Tooth Formation Results from a Large Group of Children

The aim of this study is to present further data on the timing and variation of individual permanent mandibular teeth using Demirjian stages from a large collaboration. Seven mandibular permanent teeth were assessed from dental radiographs of healthy dental patients from Australia, Belgium, Canada, England, Finland, France, South Korea and Sweden (cross-sectional study; n = 9,371, 4,710 males, 4,661 females; aged 2–18). Data are presented in three ways, namely by tooth stage for males, females, and pooled sex. Mean age at entry of each tooth formation stage (maturity data) was calculated using logistic regression and modified for age prediction. The 51% confidence interval for age within stage of individual tooth stages was calculated for use in forensic age estimation where the burden of proof is on the balance of probabilities. Average age, standard deviation, standard error, 3rd and 97th percentile within tooth stage was calculated from a uniform age sample (171 for each year of age from 3 to 16, n = 2,394). Modified maturity data and average age within stage from the uniform age distribution are two new methods of age estimation.

Role of genetic factors and ethnicity on the multiplicity of Plasmodium falciparum infection in children with asymptomatic malaria in Yaoundé, Cameroon

In this cross-sectional study, we investigated host genetic factors and ethnic variation in circulating Plasmodium falciparum merozoite surface protein 2 (msp-2) clones among children with asymptomatic malaria.Isolates from seventy two asymptomatic malaria children were used for genotyping block 3 of msp-2 gene by nested polymerase chain reaction (PCR). Sickle cell trait and glucose-6-phosphate dehydrogenase (G6PD) deficiency were analysed by restriction fragment length polymorphism of DNA products from PCR targeting codons 6 and 68 of the beta-globin (HBB) and G6PD genes respectively. ABO blood group was typed by agglutination method.A total of forty two msp-2 genotypes (20 for 3D7 and 22 for FC27) were detected for an average (standard error of mean) multiplicity of infection (MOI) of 2.45 (0.16). The MOI was statistically the same among the five identified ethnic groups (P = 0.83). The overall prevalence of sickle cell trait and G6PD deficiency were 12.50 % and 22.22 % respectively. MOI was similar between children with Hb AA and Hb AS genotypes (P = 0.42). MOI was significantly high among children with a mutant G6PD genotype (P = 0.017). MOI was significantly higher in blood group O than group A (P = 0.03).Our findings show that although ethnicity and sickle cell trait have no association with MOI, the association was observed with G6PD genotype and ABO group. The results suggest the need for extension and expansion of the current study in order to investigate the mechanisms involved.

Spatial variability in the distribution of trace metals in groundwater around the Rooppur nuclear power plant in Ishwardi, Bangladesh

Evaluation of groundwater quality is a significant concept for water resources monitoring and management. In this study, we examined the quality of groundwater of Ishwardi Upazila in Pabna District of Bangladesh. This paper has evaluated the spatial pattern and prediction of trace metals in groundwater in the study area with the using of geostatistical model. The best fitted geostatistical model has been used to identify the spatial distribution and prediction that are shown on maps. It was selected on the basis of experimental semivariogram values of twelve water quality trace metal parameters. The bestfitted model's semivariogram values have been verified by using different parameters used to evaluate the quality of geostatistical models (i.e., mean square error (MSE), root mean square error (RMSE), average standard error (ASE) and root mean square standardized error (RMSSE). The values of Barium (maximum 420.30 µg/L), Iron (maximum 0.4967 mg/L) and Arsenic (maximum 0.4983 mg/L) found in this study exceed the safe limit of Bangladesh and World Health Organization for drinking water. The results of this study demonstrate that the groundwater of the study area is no longer suitable for drinking purpose due to the high concentration of trace metals.