Effects of biotic and abiotic factors on forest biomass fractions     

Renfei Chen  Jinzhi Ran  Weigang Hu  Longwei Dong  Mingfei Ji  Xin Jia  Jingli Lu  Haiyang Gong  Muhammad Aqeel  Shuran Yao  Lizhe An  Jin-Sheng He  Karl J Niklas  Jianming Deng 《国家科学评论(英文版)》2021,8(10)

The extent to which key factors at the global scale influence plant biomass allocation patterns remains unclear. Here, we provide a theory about how biotic and abiotic factors influence plant biomass allocation and evaluate its predictions using a large global database for forested communities. Our analyses confirm theoretical predictions that temperature, precipitation, and plant height and density jointly regulate the quotient of leaf biomass and total biomass, and that they have a much weaker effect on shoot (leaf plus stem) biomass fractions at a global scale. Moreover, biotic factors have larger effects than abiotic factors. Climatic variables act equally on shoot and root growth, and differences in plant body size and age, as well as community species composition, which vary with climate in ways that drown out the variations in biomass fractions. The theory and data presented here provide mechanistic explanations of why climate has little effect on biomass fractions.  相似文献   

Experimental tests used for treatment of red weathering crusts in disintegrated granite – Egypt     

Muhammad El-Gohary   《Journal of Cultural Heritage》2009,10(4):471-479

Rock weathering is defined as the process of rocks alteration as a result of the adjustment of its internal constituents by the action of physical, chemical and biological factors, to the prevailing conditions of the atmosphere and in the environment. In humid polluted areas “red weathering” is one of the major deterioration forms that characterize most granitic rocks. Several intervention steps are required to remove and treat all surfaces affected by this form. It is one of the most aggressive forms of deterioration which are essentially composed of some complex species of clay minerals “Kaolinite, Illite, Montmorillonite and Tosudite”, in addition to some species of salts as “Gypsum” pigmented by “Hematite” as a colorant. After several investigatin techniques, these crusts need several intervention and conservation steps to remove and eliminate the aggressive effects resulted from the red crusts through three essential steps: “cleaning, gap filling and strengthening and stabilizing”. After evaluating all materials and methods that were performed by “DBN, SEM, EDX, and AAS”, the present study suggests that the most suitable cleaning methods are composed of three essential steps “dry and vacuum cleaning (DVC), ultra-sonic cleaning (USC), poultice cleaning (PC)”. Furthermore, the elected gap filling material composed of “Araldite AY-103” mixed with “Granite powder as petro-filler.” Finally, different evaluation methods proved that “Wacker H” is the most suitable strengthening and stabilizing material for consolidation purpose.  相似文献   

Relationships of Some Personality Variables to Academic Attainment of Secondary School Pupils     

Muhammad Maqsud 《教育心理学》1993,13(1):11-18

The study examined the relationship of extraversion (E), neuroticism (N), psychoticism (P), academic self‐concept and locus of control to academic attainment of lower secondary school pupils in a cross‐cultural context. Measures of E, N, P, academic self‐concept, locus of control and academic attainment were taken from 120 pupils (60 boys, 60 girls) of Standard 7 in a middle school in Bophuthatswana (Southern African region). The analysis of results revealed that E, N and P are significantly negatively related to academic attainment, while academic self‐concept and internality are significantly positively associated with measures of academic attainment. No significant sex differences were found. It was also observed that mean E and N scores of the subjects of this study were significantly lower than those given in Eysenck and Eysenck's (1975) normative data for English children of the same age.  相似文献   

The moderating role of intrinsic motivation in cloud computing adoption in online education in a developing country: a structural equation model     

Shahzad  Fakhar  Xiu  GuoYi  Khan  Imran  Shahbaz  Muhammad  Riaz  Muhammad Usman  Abbas  Adnan 《Asia Pacific Education Review》2020,21(1):121-141

Asia Pacific Education Review - In the provision of massive open online courses (MOOCs), cloud computing services enable students to synchronize their study materials anywhere, anytime, and using...  相似文献   

Microbial control of diamondback moth, Plutella xylostella L.(Lepidoptera:Yponomeutidae) using bacteria (Xenorhabdus nematophila) and its metabolites from the entomopathogenic nematode Steinernema carpocapsae     

MAHAR Ali Nawaz  MUNIR Muhammad  ELAWAD Sami  GOWEN Simon Richard  HAGUE Nigel Graham Meckenzi 《浙江大学学报(A卷英文版)》2004,5(10)

Cells and cell-free solutions of the culture filtrate of the bacterial symbiont, Xenorhabdus nematophila taken from the entomopathogenic nematode Steinernema carpocapsae in aqueous broth suspensions were lethal to larvae of the diamondback moth Plutella xylostella. Their application on leaves of Chinese cabbage indicated that the cells can penetrate into the insects in the absence of the nematode vector. Cell-free solutions containing metabolites were also proved as effective as bacterial cells suspension. The application of aqueous suspensions of cells of X. nematophila or solutions containing its toxic metabolites to the leaves represents a possible new strategy for controlling insect pests on foliage.  相似文献   

Mitigating the urban–rural educational gap in developing countries through mobile technology-supported learning     

Sharifullah Khan  Gwo-Jen Hwang  Muhammad Azeem Abbas  Arshia Rehman 《British journal of educational technology : journal of the Council for Educational Technology》2019,50(2):735-749

One form of educational inequality is the disparity that exists between urban and rural settings. Equal distribution of quality education is a challenge for developing countries due to the unavailability of resources. Various approaches to equal distribution are distance learning, telecast learning and e-learning; however, these approaches cannot achieve the desired objectives due to their limitations. This research aimed to investigate the interesting question of whether mobile technology can bring urban and rural settings closer together. A mobile application for learning Urdu grammar was designed to measure the learning gains of fourth-grade students at two different schools from urban and rural settings. A quantitative technique, the quasi-experimental pre-test and post-test method, was used to measure the effectiveness of the mobile application. The comparison of the students’ performances at the urban and rural schools illustrated the role of mobile technology in mitigating the educational gap. The present study provides evidence that children from different social backgrounds may benefit equally from mobile technology.  相似文献   

Career motivation of secondary students in STEM: a cross-cultural study between Korea and Indonesia     

Sein Shin  Arif Rachmatullah  Fenny Roshayanti  Minsu Ha  Jun-Ki Lee 《International Journal for Educational and Vocational Guidance》2018,18(2):203-231

The purpose of this study was to understand the career motivation of secondary students in science, technology, engineering, and mathematics (STEM) by comparing Korean and Indonesian students. Effects of gender and educational level on students’ STEM career motivation were also examined. To test for differences, we used Rasch analysis, 3-way ANOVA, correlation analysis, and multiple group path analysis. STEM career motivation was found to be significantly affected by interactions between country, gender, and educational level. Overall, Indonesian students had more STEM career motivation than Korean students. Korean students showed larger gender differences in STEM career motivation than Indonesian students.  相似文献   

Examining high-school students’ overconfidence bias in biology exam: a focus on the effects of country and gender     

Arif Rachmatullah 《International Journal of Science Education》2019,41(5):652-673

Accurate, rational, and scientific decision making is now considered to be the most important skill in science education. Many studies have found that overconfidence bias is one of the cognitive biases hindering people from achieving such decision making. Gender and country play crucial roles in overconfidence bias. For instance, some particular cultures and genders tend to be more overconfident than others. However, whether or not the two variables interact to influence overconfidence bias also indirectly influences decision making, especially in the context of science education. The purpose of this study is to identify the effects of country and gender on performance, confidence, and overconfidence bias in the samples of Indonesian and Korean high-school students while doing on a biology exam. The twenty-one American Association for the Advancement of Science (AAAS) questions on the topics of genetics and evolution were administered to 297 Indonesian and 235 Korean high-school students, in their first and second years. Every question was featured with a question asking students how confident they are in answering the question correctly. The two-way Analysis of Variances (2-way ANOVA) test was used to answer the research questions. Based on the analyses, we found no significance interactional effects of gender and country in test scores. In contrast, we found a significant interactional effects in both confidence in genetics and evolution. Regarding overconfidence bias, for which that we merged both concepts, we found that country had a higher influence on students’ overconfidence bias than did gender. Additionally, we found the hard-easy effect phenomenon followed overconfidence bias phenomenon. The relationships between country, gender, science education, cognitive bias, and overconfidence bias are discussed. Suggestions for reducing overconfidence bias are also provided.  相似文献   

Using think-aloud protocols and interviews in investigating writers’ composing processes: combining concurrent and retrospective data     

Muhammad M. M. Abdel Latif 《International Journal of Research & Method in Education》2019,42(2):111-123

Research comparing the use of retrospective interviews (RIs) and think-aloud protocols (TAPs) as two data sources of writers’ composing processes is almost nonexistent. Trying to address this research gap, the present study examined the data obtained from the task-specific RIs and TAPs about the composing processes of 30 second language (L2) writers. Each participant thought aloud by concurrently verbalizing thoughts while performing an argumentative writing task, and then was interviewed immediately after the think-aloud session about their composing processes. The RI and TAP data was analyzed and compared in terms of five aspects of L2 writers’ composing: pre-writing stage, while-writing planning, first language (L1) use, composing problems and problem-solving, and text reviewing and changing. Though the results generally indicate that concurrent verbalizations provide much richer data than RIs about L2 writers’ composing processes, RIs were found to be a valuable source for revealing the ‘why’ of such processes. Besides, the gap between the data provided by the two sources differed from one composing aspect to another. Recommendations for how to optimally combine and make use of the two data sources in writing process research are provided.  相似文献   

Buckling of thin-walled beams by a refined theory     

Syed Muhammad IBRAHIM  Erasmo CARRERA  Marco PETROLO  Enrico ZAPPINO 《浙江大学学报(A卷英文版)》2012,(10):747-759

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