Effect Of Environmental Constraints Research Articles

Nitrogen Removal Characteristics and Constraints of an Alphaproteobacteria with Potential for High Nitrogen Content Heterotrophic Nitrification-Aerobic Denitrification.

The discovery of heterotrophic nitrification-aerobic denitrification (HN-AD) microorganisms has opened a new window for wastewater treatment. The underlying mechanism of HN-AD, however, is not fully understood because of the phylogenetic diversity of HN-AD microbes. The isolation and characterization of new HN-AD microorganisms are encouraging for furthering the understanding of this process. In this study, we found an Alphaproteobacteria isolate W30 from a historically polluted river in China through an HN-AD microbes screening process, which we identified as Pannonibacter sp. A potential HN-AD pathway for W30 was proposed based on N conversion analyses and the successful amplification of the entire denitrification gene series. The isolate exhibited high efficiency of aerobic inorganic nitrogen transformation, which accounted for 97.11% of NH4+-N, 100% of NO3−-N, and 99.98% of NO2−-N removal with a maximum linear rate of 10.21 mg/L/h, 10.46 mg/L/h, and 10.77 mg/L/h, respectively. Assimilation rather than denitrification was the main mechanism for the environmental nitrogen depletion mediated by W30. The effect of environmental constraints on aerobic NO3−-N removal were characterized, following a membrane bioreactor effluent test under an oxic condition. Compared to known Alphaproteobacterial HN-AD microbes, we showed that Pannonibacter sp. W30 could deplete nitrogen with no NO2−-N or NO3−-N accumulation in the HN-AD process. Therefore, the application of Pannonibacter sp. W30 has the potential for developing a felicitous HN-AD technology to treat N-laden wastewater at the full-scale level.

Effects of Environmental Factors on Crop Diseases Development

Environmental factors are triggering simultaneous effects on the disease incidence and severity of crop diseases in agriculture. These both aspects are affected by various environmental factors viz. temperature, soil moisture, humidity, light, soil properties (pH and nutrients) and atmospheric carbon dioxide. The effect of environmental constraints on host and pathogen has positive, negative or neutral effects on crop disease incidence. Sometimes sole factor is responsible for profused disease incidence. On the other hand, interaction of various environmental factors causes huge intensity of diseases. Crop disease is the result of three way interaction between susceptible host, virulent pathogen and favourable environment. Elevated CO2 concentration and increased temperature influence the plant disease interaction. This review article focuses the relationship between various environmental factors and crop diseases and their role in increasing or decreasing the disease severity.

Root and shoot competition lead to contrasting competitive outcomes under water stress: Asystematic review and meta-analysis.

BackgroundCompetition is a critical process that shapes plant communities and interacts with environmental constraints. There are surprising knowledge gaps related to mechanisms that belie competitive processes, though important to natural communities and agricultural systems: the contribution of different plant parts on competitive outcomes and the effect of environmental constraints on these outcomes.ObjectiveStudies that partition competition into root-only and shoot-only interactions assess whether plant parts impose different competitive intensities using physical partitions and serve as an important way to fill knowledge gaps. Given predicted drought escalation due to climate change, we focused a systematic review–including a meta-analysis on the effects of water supply and competitive outcomes.MethodsWe searched ISI Web of Science for peer-reviewed studies and found 2042 results. From which eleven suitable studies, five of which had extractable information of 80 effect sizes on 10 species to test these effects. We used a meta-analysis to compare the log response ratios (lnRR) on biomass for responses to competition between roots, shoots, and full plants at two water levels.ResultsWater availability treatment and competition treatment (root-only, shoot-only, and full plant competition) significantly interacted to affect plant growth responses (p < 0.0001). Root-only and full plant competition are more intense in low water availability (-1.2 and -0.9 mean lnRR, respectively) conditions than shoot-only competition (-0.2 mean lnRR). However, shoot-only competition in high water availability was the most intense (— 0.78 mean lnRR) compared to root-only and full competition (-0.5 and 0.61 mean lnRR, respectively) showing the opposite pattern to low water availability. These results also show that the intensity of full competition is similar to root-only competition and that low water availability intensifies root competition while weakening shoot competition.ConclusionsThe outcome that competition is most intense between roots at low water availability emphasizes the importance of root competition and these patterns of competition may shift in a changing climate, creating further urgency for further studies to fil knowledge gaps addressing issues of drought on plant interactions and communities.

Effect of environmental constraints on multi-segment coordination patterns during the tennis service in expert performers

ABSTRACTThe aims of this study were to examine the effect of different environmental constraints on kinematic multi-segment coordination patterns during the service and its coordination with service time variability. Ten expert tennis players (Age: 34.1 ± 5.3) volunteered to take part in this study. Participants served 30 times in 3 different conditions: control, target and opposition. The order of conditions was counterbalanced between participants. A wireless 3D motion capture system (STT Co, Spain) was used to measure 7 joint motions, with a 17 degrees of freedom biomechanical model created to capture the entire service action. Results of the principal component analysis showed that 4 synergies were created; however, their roles were changed relative to the perception of the environment. The results of repeated-measures analysis of variance did not show any significant difference on total variance and individual principal components between conditions; however, one synergy pattern significantly predicted the service time variability in both control and opposition conditions. In conclusion, the findings demonstrated that expert performers reduce the joint dimensionality by creating functional synergies in different phases of service and adapt the service action according to the perception of the environment.

A novel method to model the effect of environmental constraint of geometry in the mechanism design

Few studies have considered the effect of environmental constraints throughout the entire design process of mechanical systems. Neglecting such effect might lead to misunderstanding the kinematic performance of the mechanical systems. In our work, an environment-based design concept was proposed by using passive limbs to model and analyze geometrical constraints in each step of the theoretical design process. Redesigning of a thrust system in a shield machine is taken as an example for better demonstration of this design approach. A new equivalent model of the thrust system was synthesized by using passive limbs to express environmental constraints of geometry based on the shield behavior. The uniform kinematic model was developed for the integrated equivalent mechanism of the thrust system. The effectiveness of the passive limbs in expressing environmental constraints was then evaluated by kinematical analysis. A singularity analysis was performed to assess the consistency between the equivalent model and a real thrust system. The reachable angular workspace was also analyzed to demonstrate the influence of the passive limbs as an example of environment-based parameter design. A motion simulation was performed to demonstrate the improvement of the forward kinematics by using the passive limbs to solve the singularity problem. A dexterity performance index based on the proposed model was conducted to demonstrate the kinematical property of the thrust system.

Interactions between clay portions with various contacts and subjected to specific environmental conditions

So far clays have always been considered, both experimentally and theoretically, as ideally flat and under arbitrary orientations. The goal here is to shed light on the different cases of possible contact between portions of clay, which will be subject to peculiar conditions of temperature and pressure. To this end, molecular dynamics study has been performed to investigate the evolution of nonparallel hydrated Wyoming-type Na-montmorillonite. In the present work, we study two clay structures containing two then three nonparallel portions. The contact manners between each other are considered as point and/or edge. We show that under the effect of environmental constraints, the dihedral angle of the horizontal and inclined portions tend to shrink; at the same time, the clay layers of inclined portions have a tendency to rotate. Due to this rotation, the contact of point can be considered as the evolution of the contact of edge. With the presence of water, the layers of inclined clay portions turn in different ways. The temperature effect is negligible, but the pressure plays an important role on the behaviour of clay layers.

The effects of age and traffic density on street-crossing behavior

Past research has shown that road users accept shorter time gaps when the waiting time/number of vehicles they let pass before attempting to merge into the traffic increases. While elderly pedestrians are known to be an extremely vulnerable group of road users, very few studies dealt with the effect of environmental constraints and crossing complexity on this population's safety. The present study aimed at determining whether or not street-crossing decisions and behavior of younger and older pedestrians were differently affected by a traffic flow. In an interactive street-crossing task, we assessed whether mean time gap and crossing decisions depended on the position of the gap pedestrians selected into the traffic stream. Results revealed that irrespective of their age pedestrians accepted a smaller time gap when they chose the second interval of the traffic compared to the first one. Contrasting with previous hypotheses, this traffic-related behavior was not accompanied by an increase in the decisions risk. The findings also showed that the transition threshold from rejecting to accepting time gaps was shorter when the second interval was selected compared to the first one. This increment in task constraints might help younger and older pedestrians alike to perceive action possibilities more accurately and to be better attuned to traffic conditions by comparing gaps between each other. This opens an interesting perspective in the understanding and the training of the ability of elderly road users to remain accurate in their judgements.

Options for mid-merit power generation in the UK electricity market

The article examines the future importance and growth of the mid-merit generation market, looks at the effect of environmental constraints on mid-merit plant, considers whether existing power stations can be operated efficiently at mid-merit and examines the cost and benefit implications of designing new power stations with the technology to run more flexibly.

The Effect of Environmental Constraints on Individual Economic Behavior

The Paretian measure of consumer surplus neglects the possibility that the state of individual welfare is conditioned by an economic parameter, as in the case of non-marketed environmental goods. As long as an environmental good serves as a constraint in the same way as price of an ordinary good, the equilibrium values such as price elasticity, input substitution and expenditure elasticity should vary with the quality of the environment. Therefore, spatially differentiated environmental quality yields suboptimal state of individual welfare economy, even though prices are invariant.