992 research outputs found
The verification of LANDSAT data in the geographical analysis of wetlands in west Tennessee
The reliability of LANDSAT imagery as a medium for identifying, delimiting, monitoring, measuring, and mapping wetlands in west Tennessee was assessed to verify LANDSAT as an accurate, efficient cartographic tool that could be employed by a wide range of users to study wetland dynamics. The verification procedure was based on the visual interpretation and measurement of multispectral imagery. The accuracy testing procedure was predicated on surrogate ground truth data gleaned from medium altitude imagery of the wetlands. Fourteen sites or case study areas were selected from individual 9 x 9 inch photo frames on the aerial photography. These sites were then used as data control calibration parameters for assessing the cartography accuracy of the LANDSAT imagery. An analysis of results obtained from the verification tests indicated that 1:250,000 scale LANDSAT data were the most reliable scale of imagery for visually mapping and measuring wetlands using the area grid technique. The mean areal percentage of accuracy was 93.54 percent (real) and 96.93 percent (absolute). As a test of accuracy, the LANDSAT 1:250,000 scale overall wetland measurements were compared with an area cell mensuration of the swamplands from 1:130,000 scale color infrared U-2 aircraft imagery. The comparative totals substantiated the results from the LANDSAT verification procedure
The verification of LANDSAT data in the geographical analysis of wetlands in western Tennessee
There are no author-identified significant results in this report
Alpine plant communities of Mt. Elgon.-An altitudinal transect along the Koitoboss route
Volume: 7
Metrology of pH Measurements in Brackish Waters—Part 2: Experimental Characterization of Purified meta-Cresol Purple for Spectrophotometric pHT Measurements
Spectrophotometric pH measurements allow for an accurate quantification of acid-base equilibria in natural waters, provided that the physico-chemical properties of the indicator dye are well known. Here we present the first characterization of purified m-Cresol Purple (mCP) directly linked to a primary pH standard in the salinity range 5–20. Results were obtained from mCP absorption measurements in TRIS buffer solutions. The pHT of identical buffer solutions was previously determined by Harned cell measurements in a coordinated series of experiments. The contribution of the TRIS/HCl component to the ionic strength of the buffer solutions increases toward lower salinity: This was taken into account by extrapolating the determined pK2e2 to zero buffer concentration, thereby establishing access to a true hydrogen ion concentration scale for the first time. The results of this study were extended with previous determinations of pK2e2 at higher and lower salinity and a pK2e2 model was fitted to the combined data set. For future investigations that include measurements in the salinity range 5–20, pHT should be calculated according to this pK2e2 model, which can also be used without shortcomings for salinities 0–40 and temperatures from 278.15 to 308.15 K. It should be noted that conceptual limitations and methodical uncertainties are not yet adequately addressed for pHT determinations at very low ionic strength
Ignoring carbon emissions from thermokarst ponds results in overestimation of tundra net carbon uptake
Arctic permafrost landscapes have functioned as a global carbon sink for millennia. These landscapes are very heterogeneous, and the omnipresent water bodies within them act as a carbon source. Yet, few studies have focused on the impact of these water bodies on the landscape carbon budget. We deepen our understanding of carbon emissions from thermokarst ponds and constrain their impact by comparing carbon dioxide and methane fluxes from these ponds to fluxes from the surrounding tundra. We use eddy covariance measurements from a tower located at the border between a large pond and semi-terrestrial tundra. When we take the open-water areas of thermokarst ponds into account, our results show that the estimated summer carbon uptake of the polygonal tundra is 11g lower. Further, the data show that open-water methane emissions are of a similar magnitude to polygonal tundra emissions. However, some parts of the pond's shoreline exhibit much higher emissions. This finding underlines the high spatial variability in methane emissions. We conclude that gas fluxes from thermokarst ponds can contribute significantly to the carbon budget of Arctic tundra landscapes. Consequently, changes in the water body distribution of tundra landscapes due to permafrost degradation may substantially impact the overall carbon budget of the Arctic. © 2022 Lutz Beckebanze et al
Effect of vitamin-enriched bread on the vitamin status of an isolated rural community - a controlled clinical trial
No Abstract
Person-centered approaches to examining links between self-regulation and conduct problems, attention-deficit/hyperactivity disorder, and callous-unemotional behaviors in childhood
Over the past two decades, the study of self-regulation and its associations with emerging psychopathology has become a major pursuit in developmental science. Early-childhood emotion regulation (ER) and executive function (EF), in particular, are interrelated aspects of self-regulation that have garnered extensive research and are theorized to promote social competence school readiness and achievement, and adjustment. However, the development of self-regulation is a complex process that occurs through coaction at multiple levels of analysis. Three studies were conducted to examine biobehavioral emotion responding in infancy, early childhood EF, and their prospective influences on trajectories of conduct problems (CPs), attention-deficit/hyperactivity disorder (ADHD), and callous-unemotional (CU) behaviors using multiple person-centered approaches. Study 1 used latent profile analysis (LPA) to prospectively examine the synchrony and asynchrony of infant behavioral reactivity, cortisol reactivity, and ER behaviors at 6, 15, and 24 months of age to determine whether groups of infants evidenced different patterns of arousal and regulation; and whether such patterns were bidirectionally related to parenting behavior over the same span of time. Study 2 used longitudinal latent class analysis (LLCA) to examine joint trajectories of CPs, ADHD symptoms, and CU behaviors from 3 years old to 5th grade in order to assess examine heterogeneity in CPs based on the presence of ADHD and CU behaviors. Study 3 built upon the prior two studies by in by investigating associations of infants’ emotional arousal and regulation with their later CP/ADUD/CU trajectories, as well as the role of early childhood EF in mediating these prospective associations. Results from Study 1 indicated that there is observable variation in infants’ patterns of behavioral reactivity, cortisol reactivity, and ER behaviors across infancy, and that infant emotion responding and parent sensitivity and harsh-intrusion were bidirectionally predictive of one another. Results from Study 2 showed that children did follow differing trajectories of CPs, but that these varied based on who reported their behavior (parents, teachers, or both), rather than on trajectories of ADHD symptoms and CU behaviors. In addition, these joint trajectories differentiated children’s likelihood of meeting diagnostic criteria for oppositional defiant disorder, conduct disorder, and ADHD, as well as clinically significant levels of CU behaviors, during preadolescence. Finally, results from Study 3 indicated that infants’ patterns of emotion responding were not prospectively related to their CP/ADHD/CU trajectories or their early childhood EF. However, better EF did significantly predict a decreased likelihood of following trajectories characterized by high problem behavior as rated by both parents and teachers, parents only, and teachers only. The implications for understanding the early development of self-regulation, CPs, ADHD, and CU behaviors are discussed, as is the utility of innovative person-centered approaches for understanding these phenomena
Emotion recognition deficits among children with conduct problems and callous-unemotional behaviors: differences by child race
Deficits in emotion recognition have been associated with psychopathic and callous-unemotional (CU) behaviors among adults, adolescents, and children. However, few previous studies have examined such associations exclusively during early and middle childhood. The current study used a large, population-stratified, randomly-selected sample of 2nd grade children living in areas of high rural poverty to examine group differences in emotion recognition among children showing no conduct problems or CU behaviors (typical), conduct problems without CU behaviors (CP-only), and both CP and CU behaviors (CP+CU). Primary caregivers reported on children’s conduct problems and callous-unemotional behaviors at 1st grade and children completed a computerized facial emotion recognition task at 2nd grade. Results indicated that group differences in emotion recognition accuracy were moderated by child race, with children in the typical group showing better overall accuracy and better recognition of fearful and happy faces among European American children, whereas no group differences were found among African American children. Implications for emotion socialization, etiology of CP and CU behaviors, and future directions for research and treatment are discussed
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