Platykurtic Distribution Research Articles

Evaluating the Spatial Variations in Bed Sediment and Their Depositional Environments Using Particle-Size Analysis of Wadi Fatima, Saudi Arabia

The assessment of grain size and sediment output is crucial for analyzing the pace of sediment erosion, engineering dams and reservoirs, anticipating the impact of climate change and human activities on river systems, and comprehending the presence of trace and heavy metal pathogens and micropollutants. In July 2024, 16 samples of bed sediments were collected from the mainstream of Wadi Fatima and its tributaries in the Makkah region of Saudi Arabia to identify the depositional environments and the hydrodynamic conditions using Passega diagram, Linear Discriminate Function (LDF) and bivariate plots. The results indicate that the sediments being studied exhibit polymodal properties in both the upstream and midstream regions of the main channel of Wadi Fatima. However, in the downstream region, the samples show trimodal properties. Regarding tributaries, the WFT1, WFT2, and WFT4 sediments exhibit polymodal properties, except for WFT3, which is bimodal. Folk’s classification system categorizes the samples into four distinct classes/facies: gravel, sandy gravel, gravely sand, and sand, with respective proportions of 13%, 62%, 6%, and 19%. The sediments found in Wadi Fatima contain a range of graphic mean (MZ) values, from −3.34 (indicating medium gravel) to 2.48 (indicating fine sand). On average, the MZ value is −0.79, which shows extremely fine gravel. The standard deviation (sorting (σi)) values of the samples analyzed from Wadi Fatima vary between 0.71 (moderately sorted) and 3.44 (very poorly sorted), with an average of 2.00 (very poorly sorted). The data exhibits a range of skewness (Sk) values, ranging from −0.41 (showing a very coarse Sk) to 0.82 (representing a indicating a very fine Sk). On average, the data shows a Sk value of −0.02, indicating a symmetrical distribution. The kurtosis (K) values span from 0.51 (indicating a very platykurtic distribution) to 2.65 (indicating a very leptokurtic distribution), with an average of 0.95 (indicating a mesokurtic distribution).

Collegiate women's wrestling body fat percentage and minimum wrestling weight values: time for revisiting minimal body fat percent?

The estimation of body fat percentage (BF%) in wrestling is used to determine the minimum wrestling weight (MWW) and lowest allowable weight class (MWC) in which wrestlers are eligible to compete. A 12% minimum threshold is currently used for women wrestlers, yet a potential increase for safety has been discussed. Because of the novelty of collegiate women's wrestling, there is a paucity of literature available on the body composition norms of this population. The purpose of this study was to provide a descriptive summary of BF% and MWW values of female wrestlers and how MWW values would change with the use of different BF% thresholds. Data from the 2022-2023 collegiate season were retrospectively analyzed resulting in a sample of 1,683 collegiate women wrestlers from the National Association of Intercollegiate Athletics (NAIA, n = 868) and the National Collegiate Athletics Association (NCAA, n = 815). All wrestlers completed skinfold assessments for weight certification at the start of the competition season. The skinfold values were used to estimate BF% using the Slaughter skinfold prediction equation. Frequency statistics and descriptive analysis were performed to compute normative MWW and BF% profiles. BF% thresholds of 12% (12MWW) and the BF% value defined as the lowest 5th percentile, which would be considered unusually lean, were used to determine the resulting MWW and MWC for each method. The lowest recorded weight and weight class division throughout the season was also recorded for each wrestler. There was a positively skewed (0.94) and platykurtic (1.86) distribution of MWW values. The median ± interquartile range BF% for all wrestlers was 27.4 ± 10.22%, with 17% BF representing the 5th percentile. Only 354 out of 1,579 (22.4%) wrestlers competed in their lowest allowable weight class, based on the 12MWW. Of these 354 wrestlers, the mean BF% was 21.3 ± 5.2% at weight certification with only n = 17 being at or below 12% body fat and an average weight loss of 11.1 ± 8.8 lbs. from the time of weight certification. Throughout the season, wrestlers competed at weights that were, on average (mean ± SD), 19.4 ± 16.9 lbs. higher than their 12MWW (95% CI: 18.6, 20.2 lbs. p < 0.001; effect size [ES] = 1.1), 13.4 ± 19.0 lbs. higher than the 17MWW (p < 0.001; ES = 0.70), and 8.7 ± 8.3 lbs. lower than their weight at the certification (95% CI: 8.3, 9.1 lbs. p < 0.001; ES = 1.1). Nearly all BF% values were well above the 12% threshold used to determine MWW. Increasing the minimum BF% threshold from 12% to 17% would affect a small percentage of wrestlers, likely reduce the need for excessive weight cutting, and minimize the deleterious health effects of an athlete at such a low BF%.

Genetic variability, Skewness and Kurtosis based genetics for fruit yield and yield attributing characters in F3 generation of tomato (Solanum lycopersicum L.) cross EC521069 × EC362941

An experiment was carried out at College of Horticulture, Mudigere, to access the genetic variability in F3 population of tomato cross EC521069 × EC362941. The genotypic coefficient of variation and phenotypic coefficient of variation were higher in plant height, number of fruit clusters per plant, number of fruits per plant, fruit yield per plant and average fruit weight. High broad sense heritability and genetic advance over percent of mean was observed for number of primary branches per plant, number of fruit clusters per plant, number of fruits per plant, fruit yield per plant, fruit length and fruit diameter, pericarp thickness and number of locules per fruit, indicating these traits are controlled by additive gene action. The frequency distribution showed positive skewness with positive platykurtic distribution for fruit yield per plant, fruit length, fruit diameter and average fruit weight which were negative for Number of fruit cluster per plant, number of fruits per plant, pericarp thickness and number of locules per fruit.

ANALISIS UMUR REPRODUKSI PALING AWAL DAN PALING AKHIR SERTA PUNCAK FERTILITAS PADA WANITA DI SETIAP KABUPATEN DAN KOTA DI PROVINSI BANTEN

The birth rate (fertility) is one of the factors that influences the increase in population. Banten Province has 8 districts and cities with different fertility rates. One of the fertility indicators presented in the Long Form SP2020 data is Birth Rate data by Age Group / Age Specific Fertility Rate (ASFR). The aim of this research is to determine the earliest, latest reproductive age and the age of women who have the highest fertility rates in each district and city in Banten Province. The skewness (measure of slope) and kurtosis (measure of sharpness) values of the continuous curve formed will also be studied. ASFR data presented by the Central Statistics Agency (BPS) is discrete data. Fertility rates will be approached using the MBF (Modified Beta Function) continuous fertility model. In this research, information was obtained that the earliest reproductive age in Banten Province was 15.64 years. This happened to women in Lebak Regency. Meanwhile, the latest reproductive age in Banten Province is 49.85 years. This happened to women in Pandeglang Regency. It can also be seen that the highest peak fertility rate for the population of Banten Province occurred in women aged 27.54 years in the Cilegon City area, with a peak fertility value of 0.13055. Apart from being based on calculations, this is in accordance with the curve visualization carried out using Mathematica software. The highest skewness value occurs in the continuous fertility curve for the Lebak Regency area. This means that Lebak Regency has the most left-leaning curve. All continuous fertility curves in districts and cities in Banten Province have a platykurtic distribution (flat curve) because the kurtosis value is smaller than 0.263

Study on Genetic Variability and Correlation of Yield Traits in the F3 Population Derived from Wild Introgression Lines of Swarna/Oryza nivara

Wild and related species are a source of wide genetic diversity. Back cross inbred line 166-2S derived from Swarna/Oryza nivara was crossed with Swarna to generate F3 population. This F3 population was raised in wet season of 2018 and data was collected for ten yield traits. Among all ten yield traits, single plant yield was highly associated with PH, TN, PTN, BM, TDM, HI, PL, PW and GW. HI was observed with a highly significant negative association with PH and BM. Positive skewness was observed for TN, PTN, SPY, BM, TDM and GW with platykurtic distribution and complementary gene action, suggesting an intense selection for better genetic gain. The panicle weight showed positive skewness with leptokurtic distribution, indicating the genetic regulation by only a few segregating genes. The negatively skewed and platykurtic distribution of PH, PL and HI indicated the governance of large number of dominant genes with duplicate interaction in the inheritance of these traits.

Estimate of the Vulnerability to Erosion of the Soils in the State of Paraíba

This work estimated the degree of vulnerability to soil erosion (GVES) based on the relationship between the natural erosion potential (PNE) and the soil loss tolerance limit (LTP), applied to the State of Paraíba using geoprocessing techniques for modeling the data based on information contained in the representative profiles of the Soil Bulletins of the State of Paraíba and the Agricultural Zoning of the State of Paraíba and on rainfall and altitude data. The results showed that the use of geoprocessing and kriging techniques allowed estimating and mapping the degree of vulnerability to soil erosion. The K Factor, even appearing in the very high class observed by the R and S Factors, leading the LTP to the Degree of Vulnerability to Soil Erosion (GVES) to present itself in good proportion in the middle class, smoothing the result. Despite its limitations, the information generated in this study of the knowledge of the spatial variability of vulnerability can be used in decision-making and serve as support for conservation planning, thus being able to develop strategies for management and conservation of soil and water. The distribution was symmetrical, the kurtosis indicated a platykurtic distribution, where the greatest variations in amplitude and irregular distribution were present in the variables Factor K and LTP. The greatest regularity was in Factor R, in which the Shapiro-Wilk test showed the smallest difference between them. It could be said that there is similarity and agreement between the tests used in this work and led to accept the normality of the data.

Genetic variability and correlation studies of yield and yield related attributes in BC2F2 population of sweet corn

The present study was carried out to study the genetic variability, heritability, genetic advance as percent of mean, correlation, skewness, and kurtosis of the backcross population BC2F2 derived from the cross SCM-Se-Sh-2 × DBT 17. High heritability coupled with high genetic advance was observed for cob girth, number of kernels per row, cob weight, 100 grain weight and single plant yield, suggesting additive gene action and selection of progenies based on this trait will result in higher genetic gain. Association studies showed that single plant yield was positively correlated with all yield attributes, viz., cob weight, number of kernels per row, 100 grain weight and plant height. These results depicted that cob weight, numbers of kernels per row and 100 grain weight may be used as reliable criteria for improving grain yield. Single plant yield, 100 grain weight, cob weight and plant height showed positive skewness and platykurtic distribution. This indicates that traits are governed by a large number of genes, and most of the genes exhibited complementary gene action, suggesting rigorous selection to achieve genetic gain. Overall, it is seen that this population has potential for yield improvement with enriched beta-carotene content.

Modeling variability of infiltration tests in ephemeral stream beds as a random function for uncertainty quantification

Infiltration processes are highly variable in space and time, and therefore, building reliable hydrological models without considering the variability is questionable. In this research, we propose a methodology that can systematically handle the variability in the infiltration process. The methodology is based on the theory of random functions in a dimensionless formalism that allows the derivation of a generalized model from the observed infiltration test data. The Monte Carlo technique is utilized to generate hypothetical infiltration tests that carputer the characteristics of the real tests. The methodology is applied to a case study in ephemeral stream beds located in Al Madinah Al Munawarah Province in Saudi Arabia. The measurements are made by the double-ring infiltrometer. Beta distribution fits the dimensionless cumulative infiltration relatively well at a 1% significant level at all times, and therefore, it can be used to model the uncertainty in hydrological modeling. High variability is observed in infiltration tests at the early time (a platykurtic distribution with high dispersion); however, it decreases at the late time (Leptokurtic distribution with low dispersion) since the infiltration reaches a steady infiltration. Some extreme tests show different behavior from the fourteen tests that cannot be captured by the model and therefore need special treatment.

Effect of Soil Agricultural Use on Particle-Size Distribution in Young Glacial Landscape Slopes

In the literature, mainly particle-size distribution (PSD) analyses in the soil catenas, of e.g., moraine and riverine landscapes were discussed. Analysis and comparison of PSD in moraine (ML) and ice-dammed lakes (ID-LL) landscapes were not studied. Since the landscape of ice-dammed lakes origin has diversified relief and is under intensive agricultural use, the aspects of erosion are of great importance. The changes in PSD were studied in 14 soil catenas (toposequences) of eroding soils at the upper slope (US) as well as colluvial soils at the middle (MS) and lower (LS) slopes and in the depressions (D). The PSD of the fine fractions (&lt;2 mm) was analysed according to the hydrometer method. In order to describe the effect of agricultural use on the variability of PSD in soil surface horizons, sedimentological and granulometric indices were calculated. In the studied moraine landscape, the content of coarse silt fraction was increasing in the catenal sequence from 9.7% in the US to 17.7% in the D. Similar relationships were revealed for the fine silt content. Significant differences were found between the average contents of coarse and fine silt fractions at the US as well as the LS and the D. However, such a relation was not found in the soil catena in the ice-dammed lake landscape. Eroded and colluvial soil materials were very poorly sorted with a standard deviation index of 2.65–3.69. Humus horizons of analysed soils had very fine, fine skewed PSD, mesokurtic and platykurtic distribution (ML), symmetrical, fine skewed and platykurtic distribution (I-DLL). The cluster analysis enabled the separation of two groups of soils: one group in the moraine landscape and the other in the ice-dammed lakes landscape. The PSD in studied soils was similar only among the soils within one type of landscape.

Marker‐trait association analysis for gall midge (Orseolia oryzae) resistance in a diverse rice population

AbstractDamage caused by insect herbivores, notably Asian rice gall midge, Orseolia oryzae is more prevalent in the rice‐growing belts of India's southern and north‐eastern states. As a prelude to resistant cultivar development, the identification of genomic regions for resistance in the source population is crucial. In the present investigation, 202 rice genotypes were phenotyped and assayed with genomic markers reported for gall midge resistance. Positive skewness and platykurtic distribution of response scores suggested the inheritance of gall midge resistance in the study population. The marker gm3del3 contributed the most genetic variation, followed by RM28574 and marker RM22709 explained minimal variation. A marker‐trait association analysis with a single marker‐trait linear regression approach was performed to discover gall midge resistant genomic region/genes. The marker RM17480 on chromosome 4 reported to be linked with gm3 gene was found significantly associated with the gall midge resistance genomic region with allelic effects in a negative direction favouring resistance reaction. The allelic effects of significantly associated markers were correlated significantly with the phenotypic variation of gall midge damage scores. Genes identified in the vicinity of this marker contribute to stress response reactions in rice plants. The 200 bp allele of the marker was associated with susceptibility, while the 250 bp allele was associated with resistance expression. This allelic association with trait variation suggests the importance of associated marker for utilisation in marker‐assisted selection programmes to incorporate resistance alleles into elite rice genotypes.

Probability Distribution of Soil Suction of Engineered Turf Cover and Compacted Clay Cover

It is unlikely to predict the distribution of soil suction in the field deterministically. It is well established that there are various sources of uncertainty in the measurement of matric suction, and the suction measurements in the field are even more critical because of the heterogeneities in the field conditions. Hence it becomes necessary to probabilistically characterize the suction in the field for enhanced reliability. The objective of this study was to conduct a probabilistic analysis of measured soil suction of two different test landfill covers, compacted clay cover (CC) and engineered turf cover (ETC), under similar meteorological events. The size of the two test landfill covers was 3 m × 3 m (10 ft. × 10 ft.) and 1.2 m (4ft.) in depth. The covers were constructed by excavating the existing subgrade, placing 6-mil plastic sheets, and backfilling the excavated soil, followed by layered compaction. Then the covers were instrumented identically with soil water potential sensors up to specified depths. One of the covers acted as the CC, and the other cover was ETC. In ETC, engineered turf was laid over the compacted soil. The engineered turf consisted of a structured LLDPE geomembrane overlain by synthetic turf (polyethylene fibers tufted through a double layer of woven polypropylene geotextiles). The sensors were connected to an automated data logging system and the collected data were probabilistically analyzed using the R program. There were significant inconsistencies in the descriptive statistical parameters of the measured soil suction at both covers under the same climatic conditions. Soil suction measured in the field ranged between almost 12 to 44 kPa in ETC, while it was in the range of almost 1 to 2020 kPa in the CC. The histogram and quantile-quantile (Q-Q) plot showed the data to be non-normally distributed in the field. A heavy-tailed leptokurtic (Kurtosis=13) distribution of suction was observed in the ETC with substantial outliers. In contrast, the suction distribution in CC was observed skewed to the right containing a thinner tail indicating an almost platykurtic distribution. The distribution of suction in the field under engineered turf was observed to be reasonably consistent with time compared to bare soil under the same meteorological events. The results obtained from this study revealed the engineered turf system to be an effective barrier to inducing changes in soil suction against climatic events.

Assessment of frequency distribution for the morphological and yield related traits in BC1F1, BC2F1 and BC2F2 populations in sweet corn

The nature of gene action and the number of genes controlling the traits are the vital criteria for the selection of traits. The present study is to analyze the range of variations within the population and as well as the skewness and kurtosis in backcross and selfed sweet corn populations USC1-2-3-1× UMI1230β+ and SC1107×UMI1230β+. In the BC2F2 population of SC1107×UMI1230β+, most of the traits showed positive skewness and platykurtic distribution which indicated that complementary gene action&nbsp; played a role and more number of genes is controlling the traits. In USC1-2-3-1× UMI1230β+, single plant yield recorded positive skewness. In some traits such as, the number of tassel branches, cob girth, and leaf breadth showed negative skewness and platykurtic distribution was also observed in both the cross combination which indicated prevalence of duplicate gene action. In order to fix an individual trait and for rapid genetic gain, duplicate gene action is required. &nbsp;Keywords: Sweet corn, Skewness, Kurtosis, Gene action.&nbsp

Variability, Correlation and Path Analysis for Several Quantitative Traits Derived Multi-Parent Advanced Generation Inter-Cross (Magic) F2 Population of Rice (Oryza sativa L.)

Eight quantitative traits of an F2 MAGIC population in rice were subjected to analyze variability, correlation and path analysis. The results of third and fourth degree statistics (skewness and kurtosis) showed that Individual dried straw weight, 1000-seed weight, Individual grain yield, and Number of effective tillers are associated with complementary gene interaction, requiring intense selection, while Plant height, Panicle length, Spikelet fertility percentage, and Harvest index are associated with duplicate (additive x additive) gene interactions, are suitable for mild selection. Leptokurtic distribution of Plant height, Number of effective tillers per plant, Pancile length and Spikelet fertility percentage revealed that the large number of genes in governing the traits. Platykurtic distribution of Individual dried straw weight, 1000-seed weight, Individual grain yield and Harvest index indicated fewer genes controlling the traits. However, when it comes to H2 and GAM, high values were seen in Number of effective tillers per plant, Individual dried straw weight, Individual grain yield, the traits could be explained by additive gene action and achieved through mass selection. High heritability and lower GAM of Plant height, Panicle length, 1000-seed weight and Harvest index indicated by non-additive genes with limiting the chances of direct selection. For the Pearson correlation, 1000-seed weight showed no correlation with other traits. Individual grain yield highly correlated with Number of effective tillers per plant (0.864**) and Individual dried straw weight (0.828**). The highest total effects on Individual grain yield were Number of effective tillers per plant (2.7437) and Individual dried straw weight (1.0865). Individual dried straw weight had highest direct effect on Individual grain yield at 1.0734, while most of the traits showed high indirect effect on Individual grain yield through Individual dried straw weight.

Genetic variability, trait inter-relationships, third and fourth degree statistics based genetics for fruit quality and yield traits governing shelf life in tomato (Solanum lycopersicum L.)

AbstractKnowledge on genetic architecture and inheritance of tomato shelf life contributing traits in different genetic backgrounds is a key issue for shelf life improvement. An investigation was undertaken to estimate the nature and magnitude of variability, traits inter-relationships, third and fourth degree statistics to unravel the genetics of 18 fruit quality and yield traits governing shelflife in F2 population of ‘Arka Vikas’ × ‘Red ball’ cross. The wider standardized range and higher estimates of phenotypic coefficient of variation indicated prevalence of adequate variability for fruit quality and yield traits. Fruit firmness and pericarp thickness ranged from 1.20–3.44 kg/cm2 and 2.44–5.31 mm respectively. Pulp content and shelflife ranged from 58.59–94.70% and 10.60–26.40 days respectively. Significant positive correlation with direct effect on fruit shelf life was exhibited by fruit firmness, pericarp thickness, TSS, titratable acidity, pulp content, fruit length and locule number. Positive skewness with platykurtic distribution recorded for TSS, lycopene, ascorbic acid, titratable acidity, fruit length, weight, pericarp thickness, plant height and number of branches. Negatively skewed with platykurtic distribution observed for pH, fruit diameter, firmness, pulp content, locule number, shelf life and number of clusters which signified duplicate epistasis of dominant genes in traits inheritance. The transgressive segregants for fruit quality traits indicated complementary effects of dispersed allele combinations between parents. Additive and dominance components could be exploited in the advanced segregating population by evaluating large number of families. In addition to additive effects, predominance of dominance effects of genes are important in inheritance of fruit quality traits governing shelflife.

Genetic variation of morphological and yield-related traits in backcrossed and selfed population of maize

The number of genes controlling the morphological and yield-related traits and their mode of action plays a vital role in selecting traits and favourable progenies in a segregating population. In this study, we analysed the skewness and kurtosis in the backcrossed and selfed populations of SC11-2×UMI1230β1+. Negative skewness refers to redundant gene activity, positive skewness is connected to complementary gene action. Positive kurtosis suggests the existence of gene activity controlled by a smaller number of genes. Negative kurtosis shows a lack of gene activity and is controlled by a large number of genes. The BC2F2 population of plant height and single plant yield showed positive skewness and platykurtic distribution, suggesting that the genes were governed by complementary gene action and controlled by the large number of genes. This implied need for rigorous selection to achieve a genetic gain in later generations. Cob length and kernel weight showed a duplicate gene action which implied that mild selection can fix these traits and accelerate genetic gain.

Assessment of GGE, AMMI, Regression, and Its Deviation Model to Identify Stable Rice Hybrids in Bangladesh.

Twenty-six rice hybrids were evaluated at three locations. Data were normally distributed after running the Shapiro–Wilk test. Plant height and effective tillers/hills showed leptokurtic distribution, indicating these traits were controlled by fewer genes, whereas the rest of the attributes had platykurtic distribution, indicating these traits were controlled by many genes. Most of the traits were significant for variety, locations, and variety × locations. For yield stability, the data were analyzed using additive main effect and multiplicative interaction (AMMI), genotype and genotype–environment interaction (GGE), and Eberhart and Russell’s model. Among 26 hybrids, BRRI99A × BRRI38R and BRRI hybrid dhan5 exhibited high yields at three locations. BRRI99A × BRRI45R, BRRI99A × BRRI31R, IR79156A × BRRI38R, and BRRI hybrid dhan3 were selected for mega-environments: Gazipur and Ishwardi. Among the tested locations, Gazipur (E2) and Ishwardi (E3) were identified as mega-environments for the hybrid combinations, including BRRI99A × BRRI36R, BRRI99A × BRRI49R, IR79156A × BRRI31R, IR79156A × BRRI38R, BRRI hybrid dhan5, BRRI99A × BRRI38R, BRRI99A × BRRI45R, and BRRI99A × BRRI31R based on their average action and fixity. Gazipur and Ishwardi were the best environments because their discriminative and representative ability was remarkable. The hybrid assessment, as well as area selection for hybrid rice breeding in Bangladesh, were revealed in this study. The hybrid BRRI99A × BRRI38R, BRRI99A × BRRI36R, and IR79156A × Rline7 belonged to medium-to-long slender grain types. Nowadays, the citizens of Bangladesh prefer fine-grain rice. Therefore, these fine-grain hybrids can be cultivated as preferable commercial varieties at three locations, such as Barisal, Gazipur, and Ishwardi in Bangladesh. The stable hybrids identified in the current study can be recommended for cultivation throughout the whole country without compromising the loss of grain yield of rice.

Genetic Appraisal of Wheat Progenies for Grain Yield and Yield Attributing Traits

The present investigation was carried out in F3 and F4 progenies of wheat to study gene interactions and its attributing traits during the Rabi season of 2014-15 and 2015-16. The crop was grown in research area of Wheat and Barley Section, Department of Genetics and Plant Breeding, CCS Haryana Agricultural University, Hisar. Most of the traits were studied positively skewed and were being governed by several genes indicating quantitative inheritance. Skewness and kurtosis indicated dominance based complementary gene interaction involving large number of genes having decreasing effect in the inheritance of plant height, spike length, number of grains per spike, 1000 grain weight and biological yield per plant in both the progenies However, duplicate interaction was observed for grain length, number of spikelets per spike, grain yield per plant and harvest index in both the progenies, hence, genetic gain will be rapid under mild selection. Grain yield per plant and associated traits showed platykurtic distribution indicated the involvement of few genes in inheritance of these traits. This indicates that selection could be practiced for these component traits to increase grain yield per plant. Hence, as a concluding remark based on measures of shape in both F3 and F4, progenies directional selection will effectively enhance the performance of these yield attributing traits.

The effect of grain size, porosity and mineralogy on the compressive strength of tight sandstones: A case study from the eastern Ordos Basin, China

To better understand how textural properties and mineralogy control compressive strength, this work performed the grain size analysis, porosity measurement, X-ray diffraction, microscopic observation, and mechanical tests on deep-buried reservoir sandstones in the eastern Ordos Basin, China. The results suggest that uniaxial compressive strength (UCS) declines with increasing grain size. Meanwhile, the UCS is reduced by grains >250 μm and enhanced by grains <250 μm. Sandstones with higher fractal dimensions are poorer-sorted and have platykurtic distribution, while those with low fractal dimensions are better-sorted and show leptokurtic distribution. The former tends to have larger UCS than the latter because they have more smaller grains to distribute the load over larger grains. Both the UCS and confined compressive strength (CCS) exponentially decline with porosity. Internal friction angle and influence coefficient decrease with increasing porosity, suggesting that the compressive strength of low-porosity sandstones is more sensitive to the variation of confining pressure. With regard to mineralogy, there is a weak negative relationship between UCS and quartz content. It is because textural properties control the UCS, dominating over the effects of mineralogy, or alternatively stress concentrations and the initiation of cracks preferentially occur in brittle quartz grains rather than softer materials. • Uniaxial compressive strength is reduced by grains >250 μm and enhanced by grains <250 μm. • Poorer-sorted sandstones have larger fractal dimensions and uniaxial compressive strength. • Compression-induced cracks do not preferentially propagate along grain boundaries. • The compressive strength of lower-porosity sandstones is more sensitive to confining pressure.

Laser Surface Modification of Powder Metallurgy-Processed Ti-Graphite Composite Which Can Enhance Cells' Osteo-Differentiation.

The paper examines the surface functionalization of a new type of Ti-graphite composite, a dental biomaterial prepared by vacuum low-temperature extrusion of hydrogenated-dehydrogenated titanium powder mixed with graphite flakes. Two experimental surfaces were prepared by laser micromachining applying different levels of incident energy of the fiber nanosecond laser working at 1064 nm wavelength. The surface integrity of the machined surfaces was evaluated, including surface roughness parameters measurement by contact profilometry and confocal laser scanning microscopy. The chemical and phase composition were comprehensively evaluated by scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction analyses. Finally, the in vitro tests using human mesenchymal stem cells were conducted to compare the influence of the laser processing parameters used on the cell’s cultivation and osteo-differentiation. The bioactivity results confirmed that the surface profile with positive kurtosis, platykurtic distribution curve and higher value of peaks spacing exhibited better bioactivity compared to the surface profile with negative kurtosis coefficient, leptokurtic distribution curve and lower peaks spacing.

Assessing population structure of Diadema antillarum in a shallow reef of the southeastern coast of the Dominican Republic

The sea urchin Diadema antillarum is an herbivore that plays an important ecological role in controlling benthic community structure in Caribbean reefs. After the mass mortality documented between 1982-1983, their populations were reduced by 94-99% triggering a phase shift from coral to macroalgae-dominated benthic communities across the Caribbean. Almost 4 decades after its regional collapse, it is not clear weather D. antillarum populations are recovering, thus local surveys are valuable to track the fate of this herbivore. This study aims to determine the population structure of this sea urchin in a shallow reef located southeast of the Dominican Republic. We conducted a visual survey in three haphazardly selected sites of the reef studying a total surface of 90 m2 in which test size and D. antillarum densities were measured. Overall, the mean density of D. antillarum was 1.77 ± 1.07 ind/ m2 (Mean ± SD) with an average test size of 67.3 ± 22.7 mm (Mean ± SD) a median of 70 mm and a mode of 80 mm. Test diameter had a platykurtic distribution (kurtosis = 2.53) slightly skewed to the left (skewness = -0.1). This information is valuable to establish a local baseline to follow up the population dynamics of this key species.