28 research outputs found
Gender Differences in Assessing the Impact of Inter-Parental Conflict on Students Academic Achievement Motivation in Ruiru Sub County Kenya
No full textResearch suggests children of different gender exposed to a similar environment of inter-parental conflict may have varying responses. While the impact of inter-parental conflict may be similarly damaging for both girls and boys, they may have different reactions to conflict and hostility between their parents. This necessitates the need to comprehensively understand why some children may be more vulnerable to the impact of inter-parental conflict than others. In this paper, the author seeks to establish the perception of who between the male and female students is mostly affected by inter-parental conflict in terms of academic achievement motivation. The study was guided by Fincham’s cognitive contextual framework theory and adopted a mixed method research design. A total of 281 students participated in the study. Purposeful sampling was used to select guidance and counseling teachers and parents of the students. Proportionate stratified sampling technique was used to select schools from the 13 public and 18 private schools in Ruiru sub-county as well as to select students from the chosen schools. Data was collected using four instruments: Children Perception of Inter-parental Conflict Questionnaire (CPIC) and Academic Motivation Survey (AMS) for Students, interview schedule for seven guidance and counseling teachers and focus group discussion for ten parents of the students. Data analysis was conducted both descriptively and using inferential statistics. In this, Pearson’s product moment correlation coefficient (r) was used to establish the relationship between inter-parental conflict and academic achievement motivation at 0.05 significance level. T-test was used to determine sex differences in inter-parental conflict and academic achievement motivation. The results were summarized in tables of frequency distribution and percentages. The results provided evidence that there was a significant gender difference with regard to inter-parental conflict and some domains of academic achievement motivation which were in favor of girls in both data sets. Keywords: Inter-parental conflict, gender differences, students, Ruiru sub-county, children perception, Academic achievement motivation.
Comparison of temporal phase-stepping measurement methods used for wind imaging interferometer
No full textArbuscular mycorrhizal and dark septate endophyte colonization in Artemisia roots responds differently to environmental gradients in eastern and central China
No full textArbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) are two types of root symbiotic fungi that enhance nutrient uptake by host plants and their resistance to biotic and abiotic stresses. However, it remains unclear whether AMF and DSE are synergistic or antagonistic in the presence of host plants to environmental gradients, especially on large geographical scales. To determine the relationships between AMF and DSE and their adaptability on a regional scale, we measured AMF and DSE colonization in the roots of 1023 plants of different species within the Artemisia genus collected from 81 sites across central and eastern China. We used general linear mixed models to analyze the relationships between colonization, and temperature and precipitation conditions. We found no significant correlation between AMF and DSE. The AMF colonization rate followed a significant longitudinal trend, but there was no latitudinal pattern. DSE colonization did not follow any geographical pattern. The AMF colonization rate was positively correlated with temperature and precipitation, whereas it was not significantly correlated with soil. There was no significant correlation between DSE colonization and climate or soil. Our results suggest that AMF and DSE play independent roles in the response of Artemisia to the regional environment. Therefore, studies on mycorrhizal symbiosis should discern the differential responses between AMF and DSE to climate and soil when evaluating the adaptability of the two types of symbiosis on large geographical scales. (c) 2021 Published by Elsevier B.V
Aerial and soil seed banks enable populations of an annual species to cope with an unpredictable dune ecosystem
No full textBackground and Aims Simultaneous formation of aerial and soil seed banks by a species provides a mechanism for population maintenance in unpredictable environments. Eolian activity greatly affects growth and regeneration of plants in a sand dune system, but we know little about the difference in the contributions of these two seed banks to population dynamics in sand dunes. Methods Seed release, germination, seedling emergence and survival of a desert annual, Agriophyllum squarrosum (Chenopodiaceae), inhabiting the Ordos Sandland in China, were determined in order to explore the different functions of the aerial and soil seed banks. Key Results The size of the aerial seed bank was higher than that of the soil seed bank throughout the growing season. Seed release was positively related to wind velocity. Compared with the soil seed bank, seed germination from the aerial seed bank was lower at low temperature (5/15 degrees C night/day) but higher in the light. Seedling emergence from the soil seed bank was earlier than that from the aerial seed bank. Early-emerged (15 April-15 May) seedlings died due to frost, but seedlings that emerged during the following months survived to reproduce successfully. Conclusions The timing of seed release and different germination behaviour resulted in a temporal heterogeneity of seedling emergence and establishment between the two seed banks. The study suggests that a bet-hedging strategy for the two seed banks enables A. squarrosum populations to cope successfully with the unpredictable desert environment
Quantitative deconvolution of autocorrelations and cross correlations from two-dimensional lifetime decay maps in fluorescence lifetime correlation spectroscopy
No full textFluorescence correlation spectroscopy (FCS) is a widely used method for measuring molecular diffusion and chemical kinetics. However, when a mixture of fluorescent species is taken into account, the conventional FCS method has limitations in extracting autocorrelations for different species and cross correlations between different species. Recently developed fluorescence lifetime correlation spectroscopy (FLCS) based on time-tagged time-resolved (TTTR) photon recording, which can record the global and micro arrival time for each individual photon, has been used to discriminate different species according to fluorescence lifetime. Here, based on two-dimensional lifetime decay maps constructed from TTTR photon stream, we have developed a quantitative lifetime-deconvolution FCS model (LDFCS) to extract precise chemical rates for chemical conversions in multi-species systems. The key point of LDFCS model is separation of different species according to the global distribution of fluorescence lifetime and then deconvolution of autocorrelations and cross-correlations from the two-dimensional lifetime decay maps constructed by the micro arrival times of photon pairs at each delay time. (C) 2016 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved."Strategic Priority Research Program" of Chinese Academy of Sciences [XDA09040300]; Beijing Science and Technology Project [Z151100003915077]; Beijing Nova Programme [Z151100000315081]; Beijing Talents Fund [2015000021223ZK17]SCI(E)ARTICLE19-156
A Multichannel Time-Tagged Time-Resolved (TTTR) Model for Quantification of Oligomer Concentrations Based on Antibunching Effect
No full textMolecule/protein
aggregation causes many devastating and incurable
diseases in human bodies. For example, studies have revealed that
protein oligomers formed at the early stage are toxic and may be mostly
responsible for some diseases. In the fundamental research, differentiation
of different protein oligomers and quantification of the concentrations
are important and challenging. Here, we have developed a multichannel
time-tagged time-resolved (TTTR) confocal fluorescence model based
on antibunching effect to solve the problem. The key point of the
model is that n-oligomers labeled with n-dyes cannot emit more than n photons at one time.
By assuming that all labeling dyes behave perfectly as noninteractive
individual dyes, the analytic relationship between photon-emission
probability and oligomer concentrations has been derived. Simulations
have been carried out to verify the model, in which differentiation
and concentration quantification of up to tetraoligomers can be realized
with a relative error <10% in an eight-channel TTTR confocal setup
with eight single-photon detectors
Biomass allocation between reproductive and vegetative organs of Artemisia along a large environmental gradient
No full textAbstract Background Biomass allocation reflects functional tradeoffs among plant organs and thus represents life history strategies. However, little is known about the patterns and drivers of biomass allocation between reproductive and vegetative organs along large environmental gradients. Here, we examined how environmental gradients affect biomass and the allocation between reproductive and vegetative organs. We also tested whether the allocation patterns conform optimal or allometric partitioning theory. Methods We collected 22 Artemisia species along a large environmental gradient in China and measured reproductive (infructescences including seeds) and vegetative (leaves, stems and roots) mass for each plant. We then used standardized major axes regressions to quantify the relationships between reproductive and vegetative organs and linear mixed-effect models to examine the effect of environmental gradients (climate and soil) on biomass allocation patterns. Results We found significant negative correlations between total biomass of Artemisia and the first principal component of climate, an axis that was negatively correlated with temperature and precipitation. Overall, there were significant isometric relationships between reproductive and vegetative mass. In addition, the ratio of reproductive to vegetative mass increased with the second principal component of climate (representing climate variability), but decreased with the second principal component of soil (representing bulk density and available water capacity). These patterns were consistent at the individual and interspecific levels, but were mixed at the intraspecific level. Conclusions Our findings of the plastic responses of biomass allocation to environmental gradients support the optimal partitioning theory (OPT). The isometric relationships between reproductive and vegetative organs indicate that plant growth and reproduction are intricately linked. Furthermore, the plasticity of biomass ratios of reproductive to vegetative organs to climate variability and soil physical properties suggests that the flexible allocation between growth and reproduction is crucial for successful adaptation to diverse habitats
Full Stokes spectralpolarimeter based on the polarization-difference interference imaging spectrometer
No full textSoil temperature and moisture regulate seed dormancy cycling of a dune annual in a temperate desert
No full textPlants have evolved diverse strategies to ensure their survival and regeneration in specific environments. Although temperature and soil moisture control seed dormancy, most studies have concentrated on temperature and little is known about the influence of moisture for species in the arid region. Responses of seed dormancy and germination of Agriophyllum squarrosun (Amaranthaceae), a pioneer and dominant species in Mu Us Sandland in northern China, to variations in soil moisture and temperature were examined. Our study showed that (1) freshly harvested seeds were in non-deep physiological (conditional) dormancy; (2) seeds in the soil exhibited dormancy cycling being non-dormant in spring and dormant from summer to autumn; (3) dry conditions at cold or warm temperatures alleviated dormancy; (4) germination was promoted by wetting-drying cycles; and (5) dormancy was induced by warm temperature (15/25 degrees) and particularly low soil moisture less than 14.0%. The seasonal pattern of seed dormancy/germination was regulated by seasonal rainfall and soil temperature. At the same time, a range of conditions enable dormancy break and germination regardless of soil moisture conditions allowing the species to persist in an unpredictable environment
Testing the biogeochemical niche hypothesis using leaves, stems and roots of 62 Artemisia species across China
No full textThe biogeochemical niche (BN) hypothesis is based on the concentrations of the predominant elements of a given organism to be stoichiometrically matched in order for it to function adequately. However, it is unknown how BN is represented by different plant organs and to what extent environment or evolution affects BN. We measured C, N, P, K, Ca and Mg concentrations in leaves, stems and roots of 1022 individuals of 62 Artemisia species collected across China to quantify BNs of the three organs. The BN of leaves was offset from and smaller in volume than that of stems and roots. BNs of the three organs differed in their sensitivities to environmental gradients, and leaves were less responsive to environmental variation than stems and roots in both BN volumes and positions. Environmental gradients had larger effects on BN positions than on BN volumes of all three organs. The BN volumes and positions of leaves and roots had no phylogenetic signal, while stem BN had a weak signal, that is, repeated species divergences from various Artemisia branches explained most of the BN variation of the three organs. The BN hypothesis cannot be fully tested using the elemental composition of a single organ owing to different physiological mechanisms and diverse responses of BN among organs. At least in Artemisia, leaves are strongly constrained in a limited elemental niche space to support a relatively stable supply of elements for leaf functioning, especially photosynthesis. In contrast, stems and roots develop larger elemental hypervolumes also representing nutrient storage and other functions. The BNs of Artemisia showed different environmental responses between volumes and positions, allowing these species to adjust elemental concentrations while maintaining a stable overall elemental composition under different environmental conditions. Synthesis. In conclusion, BNs of extant Artemisia populations are determined mostly by short-term phenotypic responses to current environmental conditions and/or genotypic variation, while the recently evolved species diversity results mostly from species-specific and organ-specific use of nutrients and little by early divergence in the phylogeny.</p
