Stress Time Research Articles

Methods of biodiagnostics in aquatic ecotoxicology

Introduction. Modern ecotoxicology for the detection, quantitative and qualitative assessment of the content of toxicants in the environment and living organisms uses the entire spectrum of chemical-analytical methods. However, methods of biodiagnostics are specific to this science. Materials and methods. The paper summarizes information on the use of modern methods of biodiagnostics in aquatic ecotoxicology: biomarking, biotesting and bioindication. Results. The main advantage of biodiagnostics over physicochemical methods of analysis is the ability to identify the biological consequences of the action of a single stress factor or their combination. At the same time, biodiagnostic methods allow fixing the additivity, antagonism and synergy of their joint action. Biomarking differs from other biodiagnostic methods in response time from several minutes to several days, high sensitivity and sufficient specificity, since it gives the ability to register the changes occurring in the biological system at the early stages of the action of factors at their low intensity and at the same time identify the nature of the stress factor. Biotesting has a slower response time than biomarking (from several hours to several weeks), but the ecological significance at the level of an individual is more obvious: the death of an organism, a decrease in reproductive ability up to the cessation of reproduction, disruption of growth, development, various types of behavior, etc. Bioindication is characterized by a sufficiently long-time delay of responses of supraorganismal biosystems to the action of a stress factor from several weeks to several years. At the same time, it makes possible assess more adequately and reliably the changes that have occurred over a long period of timeof stress factor action in order to predict options for the further development of ecosystems. Limitations. Methods of biodiagnostics in aquatic ecotoxicology have no restrictions on their use. However, unlike the methods of physicochemical analysis, they do not allow a quantitative, and sometimes a qualitative assessment of the stress factor. Therefore, they should be used in conjunction with the methods of qualitative and quantitative physicochemical analysis. Conclusion. Thus, the biodiagnostic approach, including biomarking, biotesting, and bioindication, together with physics and chemicals analysis plays an important role in the modern integrated system for assessing the ecological state of water bodies and anthropogenic impact on them.

Maternal Decision-Making Autonomy, Mental Health, Gender Norm Attitudes, and Social Support During Pregnancy Predict Child Care-Giving and Stunting in Rural Zimbabwe

Abstract Objectives To determine the predictive association of 7 maternal capabilities during pregnancy [physical and mental health (PH, MH), social support (SS), decision making autonomy (DMA), gender norm attitudes (GNA), mothering self-efficacy (MSE), and time stress (TS)] with subsequent child care behaviors and child length-for-age Z (LAZ) and stunting (LAZ< −2.0) at 18 months. Methods Capabilities were assessed by questionnaire among 4667 pregnant women enrolled in the Sanitation Hygiene Infant Nutrition Efficacy (SHINE). Child care behaviors and LAZ were assessed at infant ages 1, 3, 6, 12, and 18 months. We used logistic regression or generalized estimating equation models accounting for within-cluster correlation and adjusted for pre-specified covariates to test the association between each maternal capability and each outcome. Results Food security was associated with stronger maternal capabilities, across all seven domains. Mothers with more egalitarian GNA were more likely to have an institutional delivery, initiate breastfeeding early, exclusively breastfeed (EBF) to 6 months, and have soap and water at a handwashing station. Mothers with TS were less likely to EBF. Mothers with greater SS were more likely to have an institutional delivery and feed their child a diverse diet; depressed mothers were less likely to have an institutional delivery and a fully immunized child. In fully adjusted analyses, GNA and SS were significantly associated with child LAZ at 18 months and DMA and SS were significantly associated with stunting (LAZ< −2.0). Depression was more weakly associated with LAZ (P = 0.08). Conclusions Mothers who hold more equitable GNA; who are empowered to independently make decisions affecting themselves and their children; who know someone they can count on for help during times of need; and who are not depressed, are more likely to provide optimal care for their children and their children are less likely to be stunted at 18 months of age. Interventions to strengthen these maternal capabilities within nutrition programs will likely increase impact on child nutritional status and health. Funding Sources Bill & Melinda Gates Foundation (OPP1021542, OPP1143707); UK Department for International Development, Wellcome Trust (09,3768/Z/10/Z,108,065/Z/15/Z), Swiss Agency for Development and Cooperation (8,106,727).

Cotton Water Use Efficiency under Two Different Deficit Irrigation Scheduling Methods

Declines in Ogallala aquifer levels used for irrigation has prompted research to identify methods for optimizing water use efficiency (WUE) of cotton (Gossypium hirsutum L). In this experiment, conducted at Lubbock, TX, USA in 2014, our objective was to test two canopy temperature based stress indices, each at two different irrigation trigger set points: the Stress Time (ST) method with irrigation triggers set at 5.5 (ST_5.5) and 8.5 h (ST_8.5) and the Crop Water Stress Index (CWSI) method with irrigation triggers set at 0.3 (CWSI_0.3) and 0.6 (CWSI_0.6). When these irrigation triggers were exceeded on a given day, the crop was deficit irrigated with 5 mm of water via subsurface drip tape. Also included in the experimental design were a well-watered (WW) control irrigated at 110% of potential evapotranspiration and a dry land (DL) treatment that relied on rainfall only. Seasonal crop water use ranged from 353 to 625 mm across these six treatments. As expected, cotton lint yield increased with increasing crop water use but lint yield WUE displayed asignificant (p ≤ 0.05) peak near 3.6 to 3.7 kg ha−1 mm−1 for the ST_5.5 and CWSI_0.3 treatments, respectively. Our results suggest that WUE may be optimized in cotton with less water than that needed for maximum lint yield.

Comparison of deficit irrigation scheduling methods that use canopy temperature measurements

Canopy temperature (Tc) provides an easy-to-acquire indication of crop water deficit that has been used in irrigation scheduling systems, but interpretation of this measurement has proven difficult. We compared the timing of irrigation application of the Stress Time (ST) method of irrigation scheduling with the Stress Degree Hours (SDH) method on deficit irrigated cotton (Gossypium hirsutum L.) where each irrigation event delivered 5 mm of water through subsurface drip tape. A well-watered (WW) control and a dry land (DL) treatment were also part of the experimental design. We used data collected from the WW and DL treatments to develop upper and lower baselines for the Crop Water Stress Index (CWSI) appropriate for cotton grown at our location. The ST method detected drought stress earlier in the growing season when both the SDH and CWSI indicated very little drought stress. The SDH method resulted in the application of irrigations relatively later in the growing season when the CWSI also detected higher levels of drought stress. These results suggest that the adding certain micrometeorological variables to simple Tc methods of deficit irrigation scheduling may improve the ability to detect and quantify the degree of crop drought stress.

Spatial analysis of cotton (Gossypium hirsutum L.) canopy responses to irrigation in a moderately humid area

Accurate irrigation scheduling is important to ensure maximum yield and optimal water use in irrigated cotton. This study hypothesizes that cotton water stress in relatively humid areas can be detected from crop stress indices derived from canopy reflectance or temperature. Field experiments were conducted in the 2003 and 2004 crop seasons with three irrigation treatments and multiple cultivars to study cotton response to water stress. The experiment plots were monitored for soil water potential (SWP), canopy reflectance and canopy temperature. Four crop stress indices namely normalized difference vegetative index (NDVI), green NDVI (GNDVI), stress time (ST) index and crop water stress index (CWSI) were evaluated for their ability to indicate water stress. These indices were analyzed with classic mixed regression models and spatial regression models for split-plot design. Rainfall was plentiful in both seasons, providing conditions representative of irrigated agriculture in relatively wet regions. Under such wet weather conditions, excessive irrigation decreased lint yield, indicating the necessity for accurate irrigation scheduling. The four crop stress indices showed significant responses to irrigation treatments and strong correlation to SWP at shallow (0.2 m) depth. Spatial regression models were able to accurately explain the effect of irrigation treatment, while classic split-plot ANOVA models were confounded by collinearity in data across space and time. The results also verified that extreme humidity can mask canopy temperature differences with respect to ambient temperature, adding errors to canopy temperature-based stress indicators.

Bem-estar emocional de mães e pais e o exercício do papel parental: uma investigação empírica

A presente pesquisa teve três objetivos principais: 1) avaliar o bem-estar emocional, inferido como níveis de estresse de sobrecarga de tempo (ST) e sintomas de depressão (SD), em um grupo de mães e pais; 2) investigar algumas dimensões do exercício do papel parental entendidas como importantes componentes dos esquemas parentais (Ex. auto-percepção, estabelecimento de interações positivas com filhos), e 3) investigar associações entre os indicadores de bem-estar emocional parental e os diferentes componentes dos esquemas parentais. Participaram 51 casais, residentes no Rio de Janeiro, com diferentes níveis de escolaridade, maiores de 18 anos, com pelo menos um filho natural com idade inferior a 5 anos. As mães e pais responderam questionários que avaliaram ST, SD, componentes dos esquemas parentais, desejabilidade social, e dados sócio-demográficos. Os resultados, compatíveis com estudos anteriores, indicaram que uma parcela importante dos pais entrevistados apresentou níveis elevados de estresse de sobrecarga de tempo e queixas de depressão. Foram identificadas diversas associações significativas (p < 0,05) entre medidas do bem-estar e dimensões dos esquemas parentais. Foram identificadas, por exemplo, correlações entre ST e SD (r=0,24), ST e auto-percepção do papel parental (r=-0,48); SD e auto-percepção do papel parental (r = -0,45); ST e interação positiva dos pais com os filhos (r = 0,22). Entre outros aspectos, os resultados obtidos podem contribuir para um melhor entendimento das associações entre bem-estar emocional e esquemas parentais e poderão fundamentar futuros projetos de intervenção com pais e mães.

Kantian Ethics in Being and Time

Heidegger's Being and Time has been accused of espousing empty decisionism and relativism. I argue, first, that in fact Being and Time's stress on the situated character of human judgment is supplemented by a very Kantian account of being human that defines appropriate behavior towards all entities possessing a certain character. Its analysis of conscience and guilt attempts to uncover the existential basis for the distinction Kant draws between the phenomenal and the noumenal aspects of the self. Building on this analysis, I claim, Being and Time reaffirms the second version of Kant's categorical imperative, which states that humanity should never be treated merely as a means, but always also as an end in itself. In the second part of the paper, however, I argue that this proximity to Kant is part of the problem with Being and Time, that some of this work's shortcomings and dangers in relation to ethics rest precisely in its very Kantian view of what makes an entity worthy of moral concern, and what is owed to others in virtue of their being such worthy entities. As a consequence of this view, not only are all nonhuman animals excluded from moral concern, but, strangely, the intrinsic value of human well-being is itself threatened.

Behavior of temperature-based water stress indicators in BIOTIC-controlled irrigation

A subsurface drip irrigation study with cotton used canopy temperature to determine signals for irrigation control during 2002–2004. Timing of irrigation applications was controlled by the biologically identified optimal temperature interactive console (BIOTIC) protocol, which used stress time (ST) and a crop-specific optimum temperature to indicate water stress. ST was the cumulative daily time quantity when cotton canopy temperature exceeded 28°C. STs between 5.5 and 8.5 h in 1 h increments were irrigation signal criteria, which produced different irrigation regimes. This investigation examined the association among ST, daily average canopy temperature (T c), canopy and air temperature difference (T c−T a), and the relative crop water stress index (RCWSI) including their relationship with lint yield. Number of irrigation signals decreased linearly with ST at the rate of −10.2 and −8.7 irrigations per 1 h increase of ST in 2003 and 2004. There were significant curvilinear relationships between ST and the average daily stress on days with irrigation signals and for days without irrigation signals across years. The percentage of positive daily (T c−T a) values increased with ST level. ST and T c were positively related in all irrigation signal treatments with 5.5 and 6.5 h being significant in 2003 and 2004. Yield declined at the rate of 343 kg lint/ha for each 1 h increase of ST for days with irrigation signals. ST, mathematically the most simple of the canopy temperature-based parameters, provided the most consistent estimate of crop water stress and correlation with lint yield. The power of ST to characterize water stress effects on crop productivity evolves from being an integrated value of time while canopy temperature exceeds a physiologically based threshold value.

ESTABLISHING DIFFERENTIAL IRRIGATION LEVELS USING TEMPERATURE-TIME THRESHOLDS

The requirements of precision crop management or limited water supply requires that either plant water statusbe varied during the growing season to optimize crop performance or a continuous level of limited irrigation must be practicedto match irrigation water availability. Canopy temperature (TC) has been successfully used to time irrigation applicationsfor well-watered crop growing conditions. The cumulative daily time that TC exceeds a crop-specific temperature threshold,designated as stress time (ST), is used to indicate the need for irrigation. Manipulation of the ST value required to indicatethe need for irrigation changes irrigation frequency and seasonal irrigation. The ST value that generates the irrigation signalis the time threshold (TT). This study developed a procedure for estimating the relationship between TT for cotton and seasonalirrigation rates. Data were analyzed from irrigation studies that measured the water application and cotton yield responseto a range of average daily ST. All irrigation studies included a common control TT of 330 min/d above a canopy temperaturethreshold of 28C as the criteria for the irrigation signal that maintained cotton in a well-watered status. In order to developrelationships between daily ST and final yield, or water input during the season, daily ST values were calculated and averagedover the irrigation season. The same procedure was used to calculate the average TC. The procedure for identifying controlTT to establish different crop water status levels included the following steps. First, a linear relationship was defined betweenaverage daily ST and lint yield. Second, separate linear relationships were established between average daily ST and totalwater or irrigation input. Third, based on the slope of the trend line between average daily ST and yield, 1-h differences inaverage daily ST were selected to produce sufficiently large differences in total water and irrigation input to affect yield. Theseaverage ST values were 408, 468, and 528 min/d, and corresponded with control TT values of 330, 390, and 450 min/d. Thesecontrol TT should result in different amounts of water application during the growing season and produce differences in cottonyield.

ESTABLISHING CROP WATER STRESS INDEX (CWSI) THRESHOLD VALUES FOR EARLY, NON–CONTACT DETECTION OF PLANT WATER STRESS

Early, noncontact, nondestructive, and quantitative detection of plant water stress with the application ofinfrared thermometry using a crop water stress index (CWSI) was established. A CWSI model for plants grown undercontrolled environments was developed using thermodynamic principles and energy balance of the plant. CWSI thresholdvalues were established with a parametric approach. The effectiveness of the sensing technique was evaluated using timingof the stress detection by a grower. The CWSIbased technique was able to detect the stress one to two days prior to the timeof stress detection by visual observation. Overall results of this study suggested that previsual and noncontact detectionof plant water stress with infrared thermometry application using CWSI is feasible.

When will stress's time come?

When will stress's time come?