•The weight function method takes pre-existing fracture into consideration for the prediction of breakdown pressure of borehole.•The breakdown pressure calculated by weight function method is ...compared with both the 3rd party and in-house lab results, and its accuracy was proved;•The proven weight function method simplifies the prediction of breakdown pressure, and shows a great potential in improving the accuracy of breakdown pressure prediction because it captures more physical factors during rock fracturing process.
Accurate estimation of fracture gradient is critical for both drilling and hydraulic fracturing. Fracture gradient by traditional methods is greatly overestimated due to the ignorance of preexisting fractures, nonlinear near wellbore stress concentration acting on fracture surfaces, or non-uniform fluid pressure distribution inside fractures. To overcome the limitations of current methodologies, a weight function method is firstly introduced to calculate breakdown pressure where there are a pair of symmetrical radial fractures collinear with borehole axis emanating from the borehole. The results are compared against both measured breakdown pressure in both field and laboratory and results of classical fracture models. Parametric studies are conducted to investigate the influence of pre-existing crack length, orientation, in-situ stress contrast, fracture toughness, and internal pressure distribution on breakdown pressure. It indicates that breakdown pressure (1) does not always decrease with increasing dimensionless crack length at different stress contrast, (2) for the fracture with non-uniform pressure is higher than the one with constant internal pressure, and (3) increases with increasing absolute value of inclination angle1It means an angle between the local maximum horizontal principal stress and the axis of the fracture.1 and fracture toughness. Comparison of breakdown pressure by traditional and weight function methods demonstrates that breakdown pressure by traditional methods is overestimated. The proven weight function method simplifies the prediction of breakdown pressure, and shows a great potential in improving the accuracy of breakdown pressure prediction because it captures more physical factors during rock fracturing process.
PurposeImproving milling quality is expected to improve the quality of domestic rice and hence the competitiveness of Uganda's rice industry. Therefore, this study aims to assess the determinants of ...four aspects of milling, namely, choice of milling technology, millers' perceptions of the importance of paddy quality attributes, milling return and milling capacity.Design/methodology/approachMultinomial logit, semi-nonparametric extended ordered probit, linear regression and additive nonparametric models are applied to cross-sectional data obtained from a sample of 196 rice millers.FindingsPhysical, economic, institutional, technological and sociodemographic factors are found to be important determinants of the four aspects of milling. Physical factors include the distance of the mill from major town and availability of storage space at the milling premises, while economic factors include milling charge and backward integration of miller into paddy production. Contracting and use of a single-pass mill are important institutional and technological factors, respectively, and miller's household size, age, gender and education are the key sociodemographic variables.Originality/valueThe study's originality lies in its scope, especially in terms of its breadth. Without compromising the needed analytical rigor, it focuses on four aspects of milling that are critical to improving the marketing of Uganda's rice. In doing so, it provides a holistic understanding of this segment of the value chain and offers specific recommendations for improving the marketing of Uganda's rice.
This study introduces the use of high-frequency pulsed electric fields for tissue electroporation. Through the development of finite element models and the use of analytical techniques, ...electroporation with rectangular, bipolar pulses is investigated. The electric field and temperature distribution along with the associated transmembrane potential development are considered in a heterogeneous skin fold geometry. Results indicate that switching polarity on the nanosecond scale near the charging time of plasma membranes can greatly improve treatment outcomes in heterogeneous tissues. Specifically, high-frequency fields ranging from 500 kHz to 1 MHz are best suited to penetrate epithelial layers without inducing significant Joule heating, and cause electroporation in underlying cells.
Chronic shoulder pain is a very prevalent condition causing disability and functional impairment. The purpose of the study was to evaluate the relationship between pain intensity, physical variables, ...psychological vulnerability, pronociceptive pain modulation profile and disability in older people with chronic shoulder pain.
A cross-sectional study was carried out. A total of 56 participants with non-specific chronic shoulder pain of the "Complejo Hospitalario Universitario" (Granada) and 56 healthy controls were included. The outcomes evaluated were pain intensity (visual analogue scale), physical factors (dynamometry for grip strength), psychological vulnerability (Fear-Avoidance Beliefs Questionnaire and Tampa Scale of Kinesiophobia), pronociceptive pain modulation profile (pain pressure algometry) and disability (Quick Disability Arm Shoulder Hand questionnaire).
Disability showed a positive correlation with pain and psychological vulnerability (
< 0.05) and a negative correlation with pronociceptive pain variables and dynamometry (
< 0.001). Psychological vulnerability also presented a strong negative correlation with proprioceptive pain variables and dynamometry and a positive correlation with pain (
< 0.05). In regard to the pronociceptive pain modulation profile, a strong negative correlation with pain (
< 0.001) and a positive moderate correlation with dynamometry (
< 0.001) were shown.
Our results support a strong association between disability, psychological vulnerability and pronociceptive pain modulation profile in older adults with chronic shoulder pain.
The diversity of functional traits of macroinvertebrates in freshwater ecosystems is one of the current research hotspots in the field of biodiversity. Understanding the functional trait composition ...of macroinvertebrates and their factors can make the study of watershed beta diversity and river ecological security patterns more effective. Based on two field surveys conducted in September 2020 and July 2021 in the Qingyijiang (QYJ) River, the longest tributary on the south bank of the lower Yangtze River in China, we explored the functional trait compositions of macroinvertebrates and relationships between functional traits and water environment factors using functional diversity indices, beta diversity decomposition, R‐mode linked to Q‐mode, and fourth‐corner analysis methods. Our results showed that water environmental factors affected the distribution of macroinvertebrates traits, and the degree of effect was reflected by the correlation between water environmental factors and the abundance of species traits. Physical factors like flow velocity and water depth were significantly correlated with biological traits of species such as body size and swimming ability. In counterparts, some nutrient indicators significantly affected species ecological traits, such as total phosphorus, ammonia nitrogen, and chemical oxygen demand, which affected species habits and functional feeding group traits. At the same time, we also found a high turnover rate between communities in the river, reflecting the strong dispersal ability of the species. This will be an important guide for the conservation of macroinvertebrates diversity in the river. Local governments can take measures such as conducting quarterly monitoring of macroinvertebrates species; restoring riparian vegetation; limiting hardening of riverbanks and dredging of rivers; controlling wastewater discharges from residential areas on both sides of the river; controlling the use of pesticides in agricultural lands, and so on. These will become the key directions for the conservation of macroinvertebrates diversity.
Physical factors and tissue characteristics determine the transmission of light through tissues. One of the significant clinical limitations of photobiomodulation is the quantification of fluence ...delivered at application sites and optical penetration depth in vivo. There is also the difficulty of determining the distances of the application points to cover a uniformly irradiated area. Thus, the aim was to evaluate in vivo the influence of melanin on light transmission of the 660 nm and 830 nm laser wavelengths on skin and tendon. Thirty young individuals of both sexes were recruited, divided into two groups based on melanin index, and submitted to photobiomodulation protocols in the posterior region of the elbow (skin-skin) and the calcaneus tendon (skin-tendon-skin). The irradiation area was evaluated using a homemade linear array of five sensors. We found significant transmission power values for different melanin indexes and wavelengths (
p
<0.0001). Also, different equipment can generate significant differences in the transmitted power at an 830-nm wavelength. Average scattering values are 14 mm and 21 mm for 660 nm, in higher and lower melanin index, respectively. For 830 nm, values of 20 mm and 26 mm are indicated. Laser light transmission in vivo tissues is related to wavelength, beam diameter, tissue thickness, and composition, as well as melanin index. The 830-nm laser presents higher light transmission on the skin than 660 nm. The distances between the application points can be different, with higher values for 830 nm than 660 nm.
Pearlspot, Etroplus suratensis naturally thrives in the estuarine reaches of Southern peninsular India and Srilanka. The relative ease of adaptation to diverse habitats makes it a promising candidate ...for climate‐resilient aquaculture. This potential remains underexplored due to limitations in the current seed production practices. The present study focused on sustainable seed production of this species in the freshwater environment. Brooders were simultaneously maintained inside the hatchery and also in outdoor cement tanks. The breeding tanks were devoid of bottom substrate and planter pots were kept for egg attachment. The indoor fibreglass tank had an internal airlift filtration and outdoor tanks had an external filter connected to the filter bed. The modified captive breeding approaches employed were successful in obtaining 178 spawning from 44 pairs in 2 years. The indoor facility yielded 56 spawning from 15 pairs and the outdoor system yielded 122 spawning from 29 pairs. Pearlspot was found to spawn throughout the year with two distinct peaks, a minor peak in July–August and a major peak during December–January. Subsequently, spawning declined from February to June with an intermittent spurt in March. The peak spawning period distinctly differed between the breeding systems employed. The interval between successive spawning ranged from 10 to 308 days, with 46% of repetitive spawning occurring within 10 to 30 days. Pairs exhibited parental care by cleaning the substratum, protecting territory, caring for eggs and young ones. The clutch size varied from 347 to 2548, depending on the size, spawning frequency and inter‐spawning interval. The indoor tank gave an average egg count of 1104 ± 192 (mean ± SD) and that was 747 ± 21 (mean ± SD), in the outdoor system. The hatching rate with ex‐situ incubation was 88.6% ± 2% for outdoor and 77.4% ± 4.6% for indoor breeding tanks. The eggs hatch in about 66 to 72 h post spawning at a water temperature of 26 to 30°C. The water temperature and photoperiod are found to be important physical factors influencing spawning in Pearlspot. The water temperature of 27 to 30°C with a shorter day length of 11:30 to 12:00 are ideal for getting continuous spawning. Adopting an integrated breeding approach can achieve year round production cost effectively.
Knowledge of factors affecting the diversity of benthic invertebrates is very important for biodiversity conservation, for monitoring, restoring and maintaining aquatic ecosystems. The purpose of ...this study was to investigate how the diversity and distribution of freshwater mollusks related to environmental factors. Twelve species of freshwater mollusks were identified during a survey of 15 thermokarst lakes in the Gydan Peninsula, Russia. Canonical correspondence analysis (CCA) was used to study the relationships between environmental variables and species abundance. The first CCA axis correlated with the content of macro-ions, mainly Mg
2+
, Na
+
, Cl
−
, substrate types, and plant remnants. Along the second CCA axis stations were ordered by depth and the presence of mosses. We found that the type of substrate, depth, abundance of mosses and hydrochemical parameters play an important role in the distribution of the mollusks in thermokarst lakes. These results expand our understanding of mollusks ecology in thermokarst lakes, and identify environmental stressors important for the performance of abiotic control.
The dynamics of frictional interfaces plays an important role in many physical systems spanning a broad range of scales. It is well known that frictional interfaces separating two dissimilar ...materials couple interfacial slip and normal stress variations, a coupling that has major implications on their stability, failure mechanism, and rupture directionality. In contrast, it is traditionally assumed that interfaces separating identical materials do not feature such a coupling because of symmetry considerations. We show, combining theory and experiments, that interfaces that separate bodies made of macroscopically identical materials but lack geometrical reflection symmetry generically feature such a coupling. We discuss two applications of this novel feature. First, we show that it accounts for a distinct, and previously unexplained, experimentally observed weakening effect in frictional cracks. Second, we demonstrate that it can destabilize frictional sliding, which is otherwise stable. The emerging framework is expected to find applications in a broad range of systems.
•Study assesses and monitors deforestation and fragmentation in forest ecosystems of Assam.•Multi-Layer Perceptron neural network modeling was used for predicting the spatial distribution of ...deforestation.•Evaluated the rate of changes in forests.•The results of fragmentation analysis have indicated the reduction of core forests.•Identified the deforestation hotspots.
This study has assessed forest cover changes, rate of deforestation, levels of fragmentation and modeled the spatial dynamics of deforestation and forest fragmentation in Assam, India. The analysis of the forest change shows that between 1975 and 2015, the area coverage of forest has reduced from 23749km2 (30.3% of the state geographical area) to 21145km2 (27% of the state geographical area). The total predicted forest area of Assam is 20189km2 (25.7%) for 2030. Forest and non-forest classes were evaluated in order to assess changes and to study influence of five physical factors—distance from road and settlement areas, elevation, slope and distance from the water bodies on the deforestation. The Multi-Layer Perceptron neural network modeling was used for predicting the spatial distribution of deforestation. According to the Cramer coefficients, the elevation was strongly associated with deforestation in Assam followed by the slope, distance to water bodies and the distance to roads. The forest areas undergoing high concentration of negative changes have been modelled in the form of deforestation hotspots by using optimised hotspot tool. The results of fragmentation analysis have indicated the reduction of core forests throughout the study period. The spatial database generated in the study is a useful input for understanding of the impact of deforestation and fragmentation on biodiversity and land use change.
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