scholarly journals Friend or Foe? Exploring the Factors that Determine the Difference Between Positive and Negative Effects on Photosynthesis in Response to Insect Herbivory

10.5772/26064 ◽  
2012 ◽  
Author(s):  
John Paul Dlano Frier ◽  
Carla Vanessa Snchez Hernndez ◽  
Axel Tiesse
Keyword(s):  
Insect Herbivory ◽  
Negative Effects ◽  
The Difference

scholarly journals Gender Differences And Psychological Impacts In Higher Education During Covid-19 Pandemic

2021 ◽  
Vol 7 (2) ◽  
pp. 290
Author(s):  
Iswadi Iswadi ◽  
Apriyanto Apriyanto
Keyword(s):  
Higher Education ◽  
Online Learning ◽  
Negative Effects ◽  
Male And Female ◽  
Postgraduate Students ◽  
Learning Platform ◽  
Significant Difference ◽  
E Learning ◽  
Efl Students ◽  
The Difference

<p><em>E-learning during covid-19 pandemic gives positive and negative effects on students’ psychology. One of the effects of E-Learning is students whose negative and positive perception towards the process of E-Learning. The objectives of the study are to know (1)  The difference perception between male and female EFL post-graduate students of the use of online learning platforms? (2). Impacts psychologically of E-learning during Covid-19 to female and male EFL students in higher education. The method of the study is mixed research with the explanatory sequential design. The participants were 31 EFL postgraduate students in PGRI Indraprasta University. The data collection technique of the study was questionnaires with a Likert scale and an open interview. The data analysis technique of the study is an independent sample t-test with SPSS 22.0 version and collection, reduction, display, and conclusion. The results of the study are: (1) There is no significant difference perception between male and female EFL postgraduate students of the use of online learning platform because the significance value (0.695) which is bigger than 0.05. (2)  E-learning during the Covid-19 pandemic did not  give anxiety, fear, fatigue, and saturation to female and male EFL students in higher education. Implication of this research is University must develop LMS (Learning Management System) for teaching EFL students</em></p>

scholarly journals Fertilization of Algal Resources By an Exotic Snail May Facilitate Invasion

2003 ◽  
Vol 27 ◽  
pp. 116-122
Author(s):  
Leslie Riley ◽  
Mark Dybdahl ◽  
Robert Hall
Keyword(s):  
Chlorophyll A ◽  
Field Experiments ◽  
Gross Primary Production ◽  
Nutrient Recycling ◽  
Algal Growth ◽  
Grazing Pressure ◽  
Nitrogen Excretion ◽  
Macroinvertebrate Communities ◽  
Negative Effects ◽  
The Difference

We studied positive and negative effects of snail consumers on their resource to determine if positive consumer effects may be facilitating invasion. Consumer- resource interactions often focus on losses to the resource, even though the resource might benefit if consumers recycle nutrients. The New Zealand mudsnail, Potamopyrgus antipodarum, an exotic in western U.S. rivers, attains high densities and dominates macroinvertebrate communities. In one well-studied river, it consumes the majority of primary productivity, cycles most nitrogen and can grow faster at higher densities. In field experiments, we tested the hypothesis that this invasive grazer stimulates algal growth via nitrogen excretion, which might explain its self-facilitation and invasiveness. Using in-stream cages subdivided into "with snails" and "without snails" sections, we examined the response of periphytic algae to snail grazing and excretion and snail excretion alone at various levels of snail biomass. We found that chlorophyll a and GPP (gross primary production) decreased as the biomass of snails increased in the grazed sections. Snail excretion, in the absence of grazing, increased both chlorophyll a and GPP, demonstrating a positive effect of snails on the resource, consistent with the nutrient recycling and enrichment hypothesis. We found no evidence for increased algal growth at intermediate snail densities in grazed treatments, as predicted by the Herbivore Optimization Curve hypothesis. However, the difference in chlorophyll a between "with snails" and "without snails" treatments increased as snail biomass increased. This suggests that snail compensation of the resource, through excretion, decreases at extremely high levels of grazing pressure and the net effect of snail grazing becomes negative. Together, these results suggest that invasiveness in some rivers may be fostered by this self-facilitation and recycling of essential nutrients.

Reform and innovation of artificial intelligence technology for information service in university physical education

2020 ◽  
pp. 1-11
Author(s):  
Jianye Zhang
Keyword(s):  
Artificial Intelligence ◽  
Big Data ◽  
Physical Education ◽  
Information Service ◽  
Management Decision ◽  
Negative Effects ◽  
Education Management ◽  
Depth Analysis ◽  
Artificial Intelligence Technology ◽  
The Difference

This article analyzes the reform of information services in university physical education based on artificial intelligence technology and conducts in-depth and innovative research on it. In-depth analysis of the relationship between big data and the development and application of information technology such as the Internet, Internet of Things, cloud computing, to clarify the difference and connection between big data, informatization and intelligence. Artificial intelligence will bring opportunities for changes in data collection, management decision-making, governance models, education and teaching, scientific research services, evaluation and evaluation of physical education in our university. At the same time, big data education management in colleges and universities faces many challenges such as the balance of privacy and freedom, data hegemony, data junk, data standards, and data security, and they have many negative effects. In accordance with the requirements of educational modernization, centering on the goal of intelligent and humanized education management, it aims existing issues in college physical education management.

scholarly journals Consequences of barriers and changing seasonality on population dynamics and harvest of migratory ungulates

2020 ◽  
Vol 13 (4) ◽  
pp. 595-605
Author(s):  
Bram Van Moorter ◽  
Steinar Engen ◽  
John M. Fryxell ◽  
Manuela Panzacchi ◽  
Erlend B. Nilsen ◽  
...  
Keyword(s):  
Climate Change ◽  
Population Dynamics ◽  
Population Size ◽  
Spatial Dynamics ◽  
Infrastructure Development ◽  
Negative Effects ◽  
Behavioral Avoidance ◽  
Animal Populations ◽  
The Difference ◽  
Global Threat

AbstractMany animal populations providing ecosystem services, including harvest, live in seasonal environments and migrate between seasonally distinct ranges. Unfortunately, two major sources of human-induced global change threaten these populations: climate change and anthropogenic barriers. Anthropogenic infrastructure developments present a global threat to animal migrations through increased migration mortality or behavioral avoidance. Climate change alters the seasonal and spatial dynamics of resources and therefore the effects of migration on population performance. We formulated a population model with ideal-free migration to investigate changes in population size and harvest yield due to barriers and seasonal dynamics. The model predicted an increasing proportion of migrants when the difference between areas in seasonality or carrying capacity increased. Both migration cost and behavioral avoidance of barriers substantially reduced population size and harvest yields. Not surprisingly, the negative effects of barriers were largest when the population benefited most from migration. Despite the overall decline in harvest yield from a migratory population due to barriers, barriers could result in locally increased yield from the resident population following reduced competition from migrants. Our approach and results enhance the understanding of how global warming and infrastructure development worldwide may change population dynamics and harvest offtake affecting livelihoods and rural economies.

scholarly journals A Distributed AGC Method considering Two-Channel Random Delays and Their Difference between Interconnected Power Systems

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Xilin Zhao ◽  
Zhenyu Lin ◽  
Bo Fu ◽  
Yang Yang ◽  
Jimin Ma
Keyword(s):  
Power Systems ◽  
Time Delays ◽  
Frequency Control ◽  
Control Variable ◽  
Automatic Generation ◽  
Control Sequence ◽  
Negative Effects ◽  
Random Load ◽  
Sequence Selection ◽  
The Difference

With the emergence of the concept of smart grid, the networked automatic generation control (AGC) method has been more and more important for secondary frequency control due to its characteristics such as openness and flexibility. However, the networked AGC system also presents some defects such as time delays and packet dropouts. The existence of time delays makes the traditional AGC strategies more challenging. A novel AGC method is proposed in this paper to mitigate the negative effects of time delays. Firstly, a multiarea power system model is built under the consideration of two-channel time delays: from controller to actuator and from sensor to controller. More practically, the difference of delays between areas is also exhibited in the model. Thus, from the predictive characteristics of model predictive control (MPC), a method of selection with optimization is presented to obtain the appropriate control variable when delays exist. Furthermore, three cases, (a) no processing for delay, (b) control sequence selection, (c) control sequence selection with optimization, are analyzed. The frequency and area control error (ACE) performance are evaluated with step load perturbation and random load perturbation. The simulation results indicate that the system controlled by the proposed method has desired dynamic performances. Consequently, the feasibility and effectiveness of the proposed method are verified.

scholarly journals New Insights into Leaf Physiological Responses to Ozone for Use in Crop Modelling

Plants ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 84 ◽  
Author(s):  
Stephanie Osborne ◽  
Divya Pandey ◽  
Gina Mills ◽  
Felicity Hayes ◽  
Harry Harmens ◽  
...  
Keyword(s):  
Leaf Senescence ◽  
Food Production ◽  
Negative Effects ◽  
High Background ◽  
Climate Conditions ◽  
Form Part ◽  
The Difference ◽  
Mean Concentration ◽  
Future Air Pollution ◽  
Better Than

Estimating food production under future air pollution and climate conditions in scenario analysis depends on accurately modelling ozone (O3) effects on yield. This study tests several assumptions that form part of published approaches for modelling O3 effects on photosynthesis and leaf duration against experimental data. In 2015 and 2016, two wheat cultivars were exposed in eight hemispherical glasshouses to O3 ranging from 22 to 57 ppb (24 h mean), with profiles ranging from raised background to high peak treatments. The stomatal O3 flux (Phytotoxic Ozone Dose, POD) to leaves was simulated using a multiplicative stomatal conductance model. Leaf senescence occurred earlier as average POD increased according to a linear relationship, and the two cultivars showed very different senescence responses. Negative effects of O3 on photosynthesis were only observed alongside O3-induced leaf senescence, suggesting that O3 does not impair photosynthesis in un-senesced flag leaves at the realistic O3 concentrations applied here. Accelerated senescence is therefore likely to be the dominant O3 effect influencing yield in most agricultural environments. POD was better than 24 h mean concentration and AOT40 (accumulated O3 exceeding 40 ppb, daylight hours) at predicting physiological response to O3, and flux also accounted for the difference in exposure resulting from peak and high background treatments.

Responses of seedling transplants to environmental variations in contrasting habitats of Central Amazonia

2005 ◽  
Vol 21 (4) ◽  
pp. 397-406 ◽  
Author(s):  
Julieta Benítez-Malvido ◽  
Miguel Martínez-Ramos ◽  
José Luis C. Camargo ◽  
Isolde D. K. Ferraz
Keyword(s):  
Secondary Forest ◽  
Insect Herbivory ◽  
Forest Fragment ◽  
Negative Effects ◽  
Old Growth ◽  
Seedling Performance ◽  
Relative Growth Rates ◽  
Seedling Size ◽  
Old Growth Forest ◽  
Contrasting Habitats

In the Central Amazon we investigated whether seedling performance (survival, and relative growth rates in height and leaf numbers) was affected by initial seedling size (height and leaf numbers) in habitats that varied in their degree of human disturbance: cattle pasture, young secondary forest, 1-ha forest fragment and old-growth forest. Additionally, effects of photosynthetically active radiation (PAR), litter standing crop (LSC) and insect herbivory were evaluated 12 mo after transplantation in seedlings from the native canopy trees Chrysophyllum pomiferum, Micropholis venulosa and Pouteria caimito. Seedling performance changed rank across the understorey environment depending on species. Seedlings of Chrysophyllum thrived in all conditions but under high PAR, Micropholis thrived only in intermediate light conditions, whereas Pouteria thrived under high PAR. Effects of initial seedling size, PAR and herbivory after 1 y were specific to species, whereas LSC had no effect on performance. Initially larger seedlings resulted in lower survival for Chrysophyllum and Pouteria. Herbivory affected seedling performance in all species. Negative effects of herbivory were intensified under low PAR. Overall, our results showed that, as seedlings, species of the same family and characteristic of old-growth forests respond differently to the environmental constraints present in contrasting human-disturbed conditions. Larger seedlings may not always present greater tolerance to physical and biotic mortality risks.

Reversal of anorexia with megestrol acetate (MA): Impact on quality of life (QoL) in non-metastasic lung cancer patients (pts) undergoing radiation therapy

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 18613-18613 ◽  
Author(s):  
J. Pardo ◽  
A. Mena ◽  
A. Monleon ◽  
V. Macias ◽  
J. Sole ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Lung Cancer ◽  
Radiation Therapy ◽  
Cancer Patients ◽  
Life Questionnaire ◽  
Negative Effects ◽  
Lung Cancer Patients ◽  
Related Quality ◽  
The Difference

18613 Background: Anorexia is a common and major problem in cancer patients. Its ethiology is multifactorial and has negative effects on pts QoL. Up to 30% of non-metastasic lung cancer pts receiving radiotherapy will develop anorexia during treatment. We conducted a randomized trial comparing the efficacy of two different doses of MA. The results of the first 130 pts included, presented at ASCO 2003, indicated that MA at doses of 600 mg/day is significantly more effective in the treatment of anorexia in these pts than low doses (320 mg/day) of MA. Here we present the results of the quality of life sub-study which purpose is to evaluate the effect of reversing anorexia in pts health related quality of life (HRQOL). Methods: From February 1999 to April 2003, 160 non-mestastatic lung cancer pts who developed anorexia during radiotherapy were randomized to receive either 320 mg/day or 600 mg/day of MA. All pts who developed anorexia filled up the EuroQuol (EQ-5D) quality of life questionnaire before treated with MA and the responders did it again when appetite was regained. The endpoint was improvement in pts HRQOL (defined as an increase > 5 mm in the EQVAS score between the second and first questionnaires). Results: The analysis of the EuroQuol (EQ-5D) questionnaires of the 131 pts who responded to treatment with MA shows that 106 pts (81%) had an improvement > 5 mm in the EQVAS score while 19 % did not. The difference is statistically significant (Binomial test: p < 0.0001). Regarding differences between the two series, 42 pts improved in the 320 mg arm versus 64 in the 600 mg arm which is not statistically significant (Fisher test: p = 0.501). Conclusions: Our results indicate that reversal of anorexia with MA has a clinically significant improvement in HRQOL in non-metastatic lung cancer pts undergoing radiation therapy. The absence of statistically significant differences between the two series may be due to the sample size. [Table: see text] No significant financial relationships to disclose.

The performance of the hooded gene of barley (Hordeum vulgare) in rainfed Mediterranean climates

1994 ◽  
Vol 123 (3) ◽  
pp. 313-317 ◽  
Author(s):  
A. Hadjichristodoulou
Keyword(s):  
Grain Yield ◽  
Dominant Gene ◽  
Heading Date ◽  
Grain Weight ◽  
Single Dominant Gene ◽  
Negative Effects ◽  
Volume Weight ◽  
The Difference ◽  
1000 Grain Weight ◽  
Made In

SUMMARYThe progenies of six crosses, made in 1987, between the best available hooded barley line and six selected awned barley lines were used to study the effect of the hooded gene on the performance of barley under rainfed conditions in Cyprus. A single dominant gene was found to control the hooded character. Awned genotypes on average outyielded hooded genotypes by 17%, but the difference between the two genotypes was smaller in the central plain than in the coastal area. The effect of the hooded gene on yield varied also with the combination of parents, as the superiority of the awned genotypes varied with cross from 13 to 30%. Hooded lines giving a higher grain yield than their hooded parent were identified. On average the awned genotypes had higher 1000-grain weight (5·0 g), were slightly later in heading date (1·1 days), had slightly higher volume weight (1·3 kg/hl) than hooded genotypes, but had similar plant height. The 1000-grain weight of most hooded lines was significantly higher than that of their hooded parent.In spite of the negative effects of the hooded gene on grain yield, it was concluded that it is possible to increase the yield of hooded barley for hay production by continued crossing and selection (with special emphasis on 1000-grain weight), by selecting special combinations of parents through the Bulk-Pedigree method and by growing hooded barley in suitable areas, making use of the locationdependent performance of the hooded gene.

scholarly journals The spatial distribution of soil lead pollution in the Middle Mukuvisi Catchment, Harare, Zimbabwe

2018 ◽  
Vol 5 (9) ◽  
pp. 47-55 ◽  
Author(s):  
Boycen Kumira Mudzengi
Keyword(s):  
Lead Concentration ◽  
Industrial Area ◽  
Sustainable Utilization ◽  
Lead Pollution ◽  
Negative Effects ◽  
Soil Lead ◽  
Pollution Levels ◽  
Sources Of Pollution ◽  
The Difference ◽  
River Catchments

This research determined the spatial variation in soil lead pollution in the Middle Mukuvisi Catchment in Harare. Lead is one of the commonest urban pollutants and it induces negative effects on biophysical resources and humans. Part of the study area has been target of landfill programmes dating back to the 1950s. It is also subjected to industrial discharges from the Graniteside and Masasa Industrial Areas. The study catchment was stratified into two strata namely: Strata A (8 x 105 m2) and Strata B (10 x 105 m2) upstream and downstream with respect of the centre of the landfilled area respectively. These strata were digitized in Arc View Geographic Information System (GIS). Stratification enabled the testing of differences in soil lead pollution levels in the two study strata. Thirty soil samples were then collected from random points in the study area for laboratory chemical analysis. Fifteen points were randomly selected for each stratum. The results showed that soil lead concentration varies spatially in the study catchment. In comparison the strata upstream has lower average soil lead concentration than strata downstream with respect to the centre of the landfilled area. However, the difference in soil lead concentration between the two strata is not significant (p > 0.05). This can be explained by introduction of lead into the study catchment by other sources of pollution upstream such as Masasa Industrial Area. The other sources of lead into the study strata besides landfill leachate can be leakages from fuel stations and leaded fuel spillages from vehicles. It is anticipated further research in this area will contribute to the sustainable utilization of urban river catchments, especially where they are used for dumping wastes.

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