Extended finite element-based cohesive zone method for modeling simultaneous hydraulic fracture height growth in layered reservoirs

In this study,a fully coupled hydromechanical model within the extended finite element method(XFEM)-based cohesive zone method(CZM)is employed to investigate the simultaneous height growth behavior of multi-cluster hydraulic fractures in layered porous reservoirs with modulus contrast.The coupled hydromechanical model is first verified against an analytical solution and a laboratory experiment.Then,the fracture geometry(e.g.height,aperture,and area)and fluid pressure evolutions of multiple hydraulic fractures placed in a porous reservoir interbedded with alternating stiff and soft layers are investigated using the model.The stress and pore pressure distributions within the layered reservoir during fluid injection are also presented.The simulation results reveal that stress umbrellas are easily to form among multiple hydraulic fractures’tips when propagating in soft layers,which impedes the simultaneous height growth.It is also observed that the impediment effect of soft layer is much more significant in the fractures suppressed by the preferential growth of adjoining fractures.After that,the combined effect of in situ stress ratio and fracturing spacing on the multi-fracture height growth is presented,and the results elucidate the influence of in situ stress ratio on the height growth behavior depending on the fracture spacing.Finally,it is found that the inclusion of soft layers changes the aperture distribution of outmost and interior hydraulic fractures.The results obtained from this study may provide some insights on the understanding of hydraulic fracture height containment observed in filed.

Study of the Effects of Glucocorticoid on Growth and Adult Final Height in Children with Primary Nephrotic Syndrome

Objective: To analyze the epidemiological characteristics of growth, as well as factors associated with growth retardation in children with primary nephrotic syndrome (PNS), and to investigate the effect of glucocorticoid (GC) use duration on growth retardation in these children. Methods: Clinical and laboratory data of 353 PNS children treated at our hospital from July 2014 to June 2015 were collected through the medical record management system. Height, weight, and GC usage were recorded. Follow-up assessments were conducted in August 2022 for the original group, recording height, weight, and GC usage. Height and weight were evaluated using standard deviation scores (SDS). Categorical data were analyzed using chi-square test while continuous measurement data were analyzed using t-test or rank-sum test. Linear regression was used to assess the association between two single independent variables, and logistic regression analysis was used to screen for risk factors related to growth retardation in children with PNS. Results: Among the 353 PNS children enrolled in this study, male-to-female ratio of 2.64:1 (256 males vs 97 females). A total of 119 children exhibited growth retardation, incidence rate of 33.71%. The duration of GC usage among those with growth retardation was significantly longer compared to those without it (762.81 ± 934.50 days vs 263.77 ± 420.49 days;p Conclusion: PNS children treated with GC have a high incidence of growth retardation, and a high proportion of short stature in adulthood, especially in children with growth retardation in childhood, most of them have short stature after grown up. Time of GC usage is a risk factor for growth retardation in children with PNS.

Study on height growth model of Pinus koraiensis

Growth model is an efficient way to study growing process of some factors of plants quantitatively. Height growth of Korean pine (Pinus koraiensis) was studied by using Hyperbola equation, Logistic equation, Richards equation with three parameters, and Richards equation with four parameters in this paper. The results showed that Richards equation with four parameters was the most suitable and could be turned into other theoretical equations when some parameters were given different value. The maximum height of trees could be given in advance when using Richards equation with four parameters, and it was even more corresponding to reality. In addition, a height growth model with real height of fixed age as a parameter was discussed in this paper. This kind of growth model could be used to calculate height growth of a given tree effectively.

Restored intestinal integrity,nutrients transporters,energy metabolism,antioxidative capacity and decreased harmful microbiota were associated with IUGR piglet's catch-up growth before weanling

Background:Intrauterine growth restriction(IUGR)is a major inducer of higher morbidity and mortality in the pig industry and catch-up growth(CUG)before weanling could significantly restore this negative influence.But there was limited knowledge about the underlying mechanism of CUG occurrence.Methods:Eighty litters of newborn piglets were divided into normal birth weight(NBW)and IUGR groups according to birth weight.At 26 d,those piglets with IUGR but over average body weight of eighty litters of weaned piglets were considered as CUG,and the piglets with IUGR still below average body weight were considered as NCUG.This study was conducted to systemically compare the intestinal difference among NBW,CUG and NCUG weaned piglets considering the crucial role of the intestine for piglet growth.Results:The results indicated that the m RNA expression of nutrients(amino acids,glucose,and fatty acids)transporters,and mitochondrial electron transport chain(ETC)I were upregulated in CUG piglets'gut with improved morphology compared with those NCUG,as well as the ratio of P-AMPK/AMPK protein expression which is the indicator of energy metabolism.Meanwhile,CUG piglet's gut showed higher antioxidative capacity with increased SOD and GSHPx activity,decreased MDA levels,as well as higher m RNA expressions of Nrf2,Keap1,SOD,and GSH-Px.Furthermore,inflammatory parameters including TNF-α,IL-1β,IL-6,and IL-12 factors,and the activation of MAPK and NF-κB signaling pathways were significantly elevated in the NCUG intestine,while the protein expression of ZO-1,Occludin and Claudin-1 was reduced.The alpha diversity of fecal microbiota was higher in CUG piglets in contrast with NCUG piglets,and the increased beneficial bacteria and decreased pathogenic bacteria was also observed in CUG piglets.Conclusions:CUG piglet's intestine showed comprehensive restoration including higher nutrients transport,energy metabolism,antioxidant capacity,and intestinal physical barrier,while lower oxidative stress,inflammatory response,and pathogenic microbiota.

Mining Applicable Elite Alleles of Growth Duration, Plant Height and Panicle Number per Plant by Conditional QTL Mapping in Japonica Rice

Unconditional and conditional QTL mapping were conducted for growth duration (GD), plant height (PH) and effective panicle number per plant (PN) using a recombinant inbred line (RIL) population derived from a cross between two japonica rice varieties Xiushui 79 and C Bao. The RIL population consisted of 254 lines was planted in two environments, Nanjing and Sihong, Jiangsu Province, China. Results showed that additive effects were major in all of QTLs for GD, PH and PN detected by the two methods, and the epistatic effects explained a small proportion of phenotypic variation. No interactions were detected between additive QTL and environment, and between epistatic QTL pairs and environment. After growth duration was adjusted to an identical level, RM80-160bp was detected as an applicable elite allele for PN, with an additive effect of 0.71. When effective panicle number per plant was adjusted to an identical level, RM448-240bp was detected as an applicable elite allele for GD, with an additive effect of 4.64. After plant height was adjusted to an identical level, RM80-160bp was detected as an applicable elite allele for PN, with an additive effect of 0.62, and RM448-240bp was detected as an applicable elite allele for GD, with an additive effect of 3.89. These applicable elite alleles could be used to improve target traits without influencing the other two traits.

Height/Length and Weight Growth Curves and Growth References of Children Aged 0 - 7 in Chongqing by GAMLSS

Aim: Using the generalised additive model for location, the scale and shape (GAMLSS), the standard of height (length), weight and percentage curve of children were formulated to understand the growth law in Chongqing and to provide a reference for clinical and preventive health care work of paediatrics in West China. Methods: Data were collected from the health clinic dataset of children aged 0 - 7 years in the Department of Child Health Care of a Third-Class A hospital in Chongqing from 2010 to 2017. By applying the GAMLSS technology and taking D(μ, σ, ν, τ) as the specific distribution form, BCT as the link function, P-spline function and cubic splines function as the smoothing function, the unit value of age-specific standard deviation of height (length) and weight were obtained, and the percentile map was drawn. Results: Based on the principle of minimum AIC and SBC values, BCT distribution was chosen as the model of the link function. Fitting results of height (length) and weight parameters of boys and girls, standard deviation tables of age and percentile curves were obtained. Conclusions: This study was an exploration of using GAMLSS method to establish a reference value range in the field of children’s growth and development in China. It could supplement the relevant data of Chongqing area for Reference standard for growth and development of children under 7 years of age in China, and also provide a reference for the rational diagnosis of children’s short stature and malnutrition in Chongqing.

Comparative Analyses of Height Growth Velocities of School Boys in South Korea and Japan in the Past 50 Years

The paper compares the height growth velocities of male schoolchildren in South Korea and Japan over the period 1961-2018. Growth in height was measured with the same birth cohorts, not by comparing mean height of ascending ages in the same year. Starting from a lower economic base and mean height in the 1960s, high school males aged 17 in South Korea became 3 cm taller in mean height than their Japanese peers in the mid-2000s versus 2 - 3 cm shorter in the 1960s through 1970s. Children in Japan ceased to grow taller by the end of the 1980s, not because they quit taking more animal-sourced foods, meat and milk, but because they had drastically steered away from fruit and vegetables in their diets since the end of the 1970s. Having largely converged economically with Japan, South Korean children ceased to grow any taller in the mid-2000s. More importantly, it was discovered in this study that successive cohorts in South Korea started to fall gradually but steadily in height growth velocity from 1st graders in middle school, aged 12 years to 3rd graders in high school, and aged 17 years, to be once again 3 cm below their Japanese peers in the early-2010s. Analysis of Korea Household Expenditure Surveys classified by age groups of household head, decomposed by the author, revealed that children under 20 years of age in South Korea began to steer away from fruit and, particularly, vegetables in their at-home consumption in the mid-1990s, to average only 15% of the level of older adults in their 50s in the mid-2010s. These results lend supports to the importance of fruit and vegetables as determinants in height and its growth velocities in two genetically similar nations over time and stages of economic growth.

Distortions, Growth Catch-up, and Sustainable Growth

A distortion is a departure from the allocation of economic resources from the state in which each agent maximizes his/her own welfare. Distortions can be divided into endogenous distortion(i.e. market imperfections) and policy-imposed distortion. The relationship between distortion and development is complex, thus favorable distortion would only be possible under certain conditions, where, as argued in this paper, four crucial mechanisms may play roles — advantage of backwardness, second-best principle, coordination failure and political economy perspective. Empirically, both international experience and evidence from China suggest that distortions have a positive effect on total factor productivity(TFP) in the early stages of development, but with increasing income levels this role gradually diminishes. Especially in the phases of middle and high income, the negative effects of distortions are significant and become an important factor leading to the middle-income trap. Therefore, reducing and correcting distortions is the key to achieving sustainable growth. Regarding China, it is necessary to eliminate the distortions in a clear way and let the market play the decisive role in resource allocation. Otherwise, in the name of "growth catch-up," the policy-imposed distortion will occur frequently, and the direction of market-oriented reform will become blurred and swing. Mitigating unfavorable distortions is largely a process of exploring the favorable borderline of government and market, which constitutes a major challenge for all economies.

平茬高度对杜香生长及其光合生理和次生代谢产物积累的影响

以3年生杜香(Rhododendron tomentosum)为研究对象,在黑龙江省大兴安岭地区呼中区林场内,选取林相整齐、坡面相对均匀的林分,随机设置3个20 m×20 m的平行样地,在各样地内根据五点取样法各设置5个1.0 m×1.0 m小样地;2022年6月30日,在样地内随机挑选4个小样地,各选取长势一致的10株杜香设置4个处理组(平茬高度分别为10、15、20 cm的3个处理组,未平茬的1个对照组);按照试验设计,测定杜香植株萌芽及叶片生长、叶片气体交换参数、叶片光合色素质量分数、叶片次生代谢产物质量分数,分析平茬高度对杜香生长、光合生理及次生代谢产物的影响。结果表明:(1)平茬使杜香侧枝、叶片生长得到促进,萌发枝条能力比对照组显著增强。其中,平茬高度为20 cm的处理组,侧枝长度、萌发数量最高;平茬高度为15 cm的处理组,成枝数量、叶宽、叶干质量,显著高于其他组。(2)平茬处理后,杜香的净光合速率、蒸腾速率、气孔导度、水分利用效率,均呈现出先升高后降低的趋势,其中平茬高度为15 cm的处理组的这4个指标显著高于其他组。与对照组相比,平茬处理后叶光合色素的质量分数显著提高。(3)平茬处理后,杜香叶片中的总酚、类黄酮质量分数均高于对照组;平茬处理后,杜香叶片中的精油质量分数显著低于对照组,各平茬处理组差异不显著。(4)综合研究结果,说明平茬处理能够促进杜香萌芽和生长,通过提升杜香的光合色素质量分数和气体交换能力,进而增强其光合效率,同时调节次生代谢产物的质量分数,以适应平茬处理带来的影响。

Effects of Lithological Characters on the Growth of Cunninghamia lanceolata

Objective The aim was to reveal relationship between lithological character soil and productivity of Cunninghamia lanceolata and lay a foundation for systemic management of C. lanceolata fast-growing and high yield plantation. Method By using experimental ecology method and variance analysis, the biomass and growth of planting eleven years＇ C. lanceolata on the soils with six different lithologicel characters were studied. Result The effects of soils with six different lithological characters on the height, diameter growth and biomass of C. lanceolata were different, in which the growth order of C. lanceolata was： Feldspathic quartzy sandstone （ average height 523. 270 cm, average diameter 4.720 cm, average individual biomass 5.059kg） 〉 Basalt （ average height 511. 570 cm, average diameter 4.650 cm, average individual biomass 4.848 kg） 〉 Quartzy sandstone 〉 Blastopsammite 〉 The Quarternary Period red clay 〉 Coal-series siliceous sand-shale, and the difference was smaller between the last two lithological characters. Conclusion Feldspathic quartzy sandstone and Basalt are beneficial to C. lanceolata.

Impacts of Primo MAXX Growth Regulator on the Growth of Bermuda Grass

[Objective] The aim was to investigate the effects of Primo MAXX growth regulator on growth of Bermuda grass,explore appropriate application concentration of Primo MAXX on Bermuda grass,and provide basis for the application of Primo MAXX in Bermuda meadow.[Method]The height,leaf colour and the aerial part＇s fresh weight of Bermuda grass treated with different concentrations were researched using single factor random block test.[Result]Primo MAXX application effectively reduced the height in all treatment without significant difference;appropriate application of Primo MAXX can enrich the color;and 35 days after application,Bermuda grass roots were become thicker.[Conclusion]The application of Primo MAXX with effective dose of 150-300 g/hm2 on Bermuda grass in southern China is more appropriate.

Crohn's disease and growth deficiency in children and adolescents

Nutritional concerns, linear growth deficiency, and delayed puberty are currently detected in up to 85% of patients with Crohn's disease(CD) diagnosed at childhood. To provide advice on how to assess and manage nutritional concerns in these patients, a Medline search was conducted using "pediatric inflammatory bowel disease", "pediatric Crohn's disease", "linear growth","pubertal growth", "bone health", and "vitamin D" as key words. Clinical trials, systematic reviews, and metaanalyses published between 2008 and 2013 were selected to produce this narrative review. Studies referring to earlier periods were also considered if the data was relevant to our review. Although current treatment strategies for CD that include anti-tumor necrosis factor-αtherapy have been shown to improve patients' growth rate, linear growth deficiencies are still common. In pediatric CD patients, prolonged diagnostic delay, high initial activity index, and stricturing/penetrating typeof behavior may cause growth deficiencies(in weight and height) and delayed puberty, with several studies reporting that these patients may not reach an optimal bone mass. Glucocorticoids and inflammation inhibit bone formation, though their impact on skeletal modeling remains unclear. Long-term control of active inflammation and an adequate intake of nutrients are both fundamental in promoting normal puberty. Recent evidence suggests that recombinant growth factor therapy is effective in improving short-term linear growth in selected patients, but is of limited benefit for ameliorating mucosal disease and reducing clinical disease activity. The authors conclude that an intense initial treatment(taking a "top-down" approach, with the early introduction of immunomodulatory treatment) may be justified to induce and maintain remission so that the growth of children with CD can catch up, ideally before puberty. Exclusive enteral nutrition has a key role in inducing remission and improving patients' nutritional status.

Effect of first thinning and pruning on the individual growth of Pinus patula tree species

The effect of first thinning and pruning on height, diameter at breast height （DBH）, and volume growth was studied in individual trees of Pinus patula Schiede and Deppe in Chongoni Plantation, using four plots for thinning trials. Each of the plots was 0.5 ha and subjected to one of the fol- lowing silvicultural treatments： first thinning and pruning, first thinning and no pruning, pruning and no thinning, and control （no pruning and no thinning）. The silvicultural treatments were randomized in four replicates. Fourteen years after planting, the following parameters were measured including total height, DBH, and volume. The highest DBH and volume growth was observed in thinning and pruning, while the highest growth in height was observed where there was pruning and no thinning. Clearly, both thinning and pruning are an important manage- ment option in pine species plantations in Malawi to maximize the increase in volume productivity.

Physical Growth of Children in Urban,Suburban and Rural China's Mainland:A Study of 20 Years' Change

Objective To describe secular trends on physical growth of children in China during the year of 1985‐2005 and to analyze the urban‐suburban‐rural difference and its change. Methods The measurements of height, weight and chest circumference obtained from two serial national cross‐sectional surveys for children aged 0 to 7 years in China were used to analyze the secular trends, and the growth differences among urban, suburban and rural children were compared. Results The average weight and height for both boys and girls from urban, suburban and rural areas have significantly increased in most age groups during the past 20 years; The average chest circumference increased slightly, ranging from 0.0 to 2.0 cm. From 1985 to 2005, the urban‐suburban difference in height had become smaller, and that in weight showed similar trend for children under 3 years old but became larger after 3 years old; the suburban‐rural difference both in height and weight became larger after 6 months old. The increment per decade in height was the greatest in the suburban group while the greatest increment in weight was the urban group. Conclusion Positive secular trends were observed among urban, suburban and rural areas in Chinese children under 7 years old during the 1980s and the 2000s, reflecting a rapid socio‐economic development in China.

Growth and ecophysiology of seedlings of Podocarpus falcatus in plantations of exotic species and in a natural montane forest in Ethiopia

The potential role of exotic tree plantations in facilitating successional processes on degraded areas was evaluated in southern Ethiopia by comparing seedling characteristics, transpiration and photosynthetic performance of Podocarpus falcatus seedlings in Eucalyptus plantation, Pinus plantation, adjacent natural forest and clear-felled plantation site. P. falcatus seedlings exhibited differences in architecture between Eucalyptus and Pinus plantations. They had higher leaf area, shorter internode length and greater number of lateral branches in Eucalyptus plantation. At similar vapor pressure deficit （VPD）, P. falcatus transpired much less than E. saligna, especially at higher VPDs. Analysis of fluorescence parameters in the leaves showed no significant differences in the level of dark-adapted and light-adapted fluorescence yield （Fv/Fm and ΔF/Fm′, respectively）, electron transport rate （ETR） and nonphotochemical quenching （NPQ） among seedlings grown inside plantations and adjacent natural forest, indicating similar photosynthetic performance. Nevertheless, there was evidence of photoinhibition in P. falcatus in the clear-felled site which had low fluorescence yield but high values of NPQ as protection from photoamage. The light response curves of ETR, NPQ and ΔF/Fm′ showed similar light saturation behavior among the seedlings grown inside plantations and natural forest and suggested a sequence of light-adapted to shade-adapted behavior in Natural forest 〉 Eucalyptus plantation 〉 Pinus plantation. The results show the structural flexibility, better water-use and adaptability of P. falcatus in its use of the understory environment of plantation species.

Mining Elite Alleles of Growth Duration and Productive Panicle Number per Plant by Association Mapping with Conditional Phenotypic Value in Japonica Rice

To provide genetic information and materials for breeding hybrid japonica rice with wide adaptability and strong competitive advantage of yield, elite alleles and their carrier varieties of growth duration （GD） and productive panicle number per plant （PN） were detected. A natural population composed of 94 japonica varieties was phenotyped for the GD, PN and plant height （PH） in two environments. The conditional phenotypic data were transferred by the linear model method in software QGAStation 1.0, and association mapping based on the unconditional and conditional phenotype values of GD and PN was analyzed by using general linear model in software TASSEL. A total of 34 simple sequence repeat （SSR） marker loci associated with GD and PN were detected in the two environments. Among them, 15 were associated with GD, and 19 were associated with PN. Four elite alleles of RM8095-120bp, RM7102-176bp, RM72-170bp and RM72-178bp were associated with GD, and their carrier varieties were Hongmangshajing, Nipponbare, Hongmangshajing and Nannongjing 62401, respectively. These elite alleles from the carrier varieties can shorten GD by 2.03-9.93 d when they were introduced into improved materials. RM72-182bp associated with PN was an elite allele, and its carrier variety was Xiaoqingzhong. It can increase PN by three when introduced into improved materials. Moreover, these elite alleles can be used to improve target traits without influencing another two traits.

Seedling defoliation of cereal crops increases peanut growth and yield in an intercropping system

Intercropping cereals and legumes is practiced widely in the world for improving yields and economic benefits. Shorter legume crops in intercropping are shaded by taller cereals, substantially reducing legume growth and yield. Reducing shade in intercropping by shortening the plant height of cereals by seedling defoliation has been proposed as a practical approach to increase crop yields and land productivity. A two-year field experiment was conducted to investigate the effect of defoliation of cereal crops at seedling stage on the growth and yield of peanut(Arachis hypogaea L.) intercropped with corn(Zea mays L.) or millet(Setaria italica L.). In comparison with non-defoliation controls, defoliation reduced final plant height by 29 cm on average for corn and 18 cm for millet. Photosynthetically active radiation on peanut in intercropping systems with corn or millet intercropping was respectively 27.0% and 22.8% higher than those in controls, significantly improving the light environment of intercropped peanut. Net photosynthetic rates of peanut were on average 25.5% higher in corn and peanut intercropping and 19.6% higher in millet and peanut intercropping than those in non-defoliation controls. Total biomass of intercropped peanut increased owing to increased root growth. Across two years, yield of peanut intercropped with corn was 27.7% and with millet 32.8% higher than those of controls. Defoliation of cereal crops did not affect corn yield but significantly decreased millet yield by 24.5%. Our results suggest that applying seedling defoliation in intercropped corn could increase peanut yield without compromising corn yield in an intercropping system.

Study on the Influence of Climatic Change on Pasture Growth in Inner Mongolia Grassland

Through analyzing statistically metrological observation data from 1971 to 2010 and pasture data from 1983 to 2012 at 6 animal husbandry meteorological testing stations of Inner Mongolia grassland, the conclusions were drawn. Those were that annual average temperature rose in a straight line in Inner Mongolia grassland, and the increase rates of annual average temperature in meadow steppe and typical steppe were 0.40 and 0.34 ℃/10 a respectively. Annual rainfall had 10-year cyclical characteristics, and precipitation in the 1990s was the most but reduced significantly after 2000. Climate experienced the cold wet -cold dry -warm wet -warm dry periods. Warm and dry climate made the average heights of pasture in meadow steppe and typical steppe of Inner Mongolia cut down 2.4 and 9.3 cm in nearly 12 years than that in the 1990s; the average coverage of herbage decreased by 11% and 13%; the average hay yields reduced by 1 019.8 and 671.4 kg/hm^2.

Growth of Scotch Pine （Pinus sylvestris L.） Plantation in Northern Mongolia

The growth of Scotch pine in Northem Mongolian plantations was studied to determine variation in heights, diameters at breast height （DBH）, and main and annual volume increment of stem volumes in relation to plantation age. The study was conducted in the Tujyin Nars region, where six plantations ranging from 9 to 25 years old were selected for the assessment. Results indicate that the growth of Scotch pine on the plantations did not vary by site, and that more intensive annual increment in height was observed on Scotch pine plantations between the ages of 8 to 15 years. The amount of annual height increment and radial growth improves regularly up to 9 to 11 years of age and then the intensity of annual increment declines due to competition for light and nutrients. Additionally, there was a reduction in the number of trees per ha. Results suggest that it is necessary to implement forestry thinning which aimed at improving growth of Scotch pine on the plantations because intensity of annual increment in height and diameter reduces regularly due to restriction of growing condition.

Response of photosynthesis,growth,and acorn mass of pedunculate oak to diff erent levels of nitrogen in wet and dry growing seasons

The objective was to examine the effects of optimal leaf nitrogen levels>2.0%and suboptimal levels<2.0%,nitrogen nutrition on net photo synthetic rate,stem diameter increment,height growth increment and acorn mass of pedunculate oak during 2010 in the absence of drought stress and during 2011 under the impact of moderate drought stress.According to the results,moderate drought stress significantly reduced net photo synthetic rate,stem diameter increment and height growth increment,while acorn mass was not affected.Suboptimal nitrogen nutrition significantly reduced the net photo synthetic rate and stem diameter increment only in the wet year,acorn mass in both wet and dry years,while height growth increment was not significantly reduced by suboptimal nitrogen nutrition in either year.The results indicate that optimal nitrogen levels can stimulate photo synthetic rate and stem diameter increment of pedunculate oak only in the absence of moderate drought stress.Moreover,the results show that moderate drought stress is a more dominant stressor for photosynthesis and growth of pedunculate oak than suboptimal nitrogen nutrition,while for acorn development,it is the more dominant stressor.