Examples play a significant role at construction and reconstruction of math concepts. Good educational examples like a clear monitor, act as means for connecting learners, teachers and concepts. This study examines math teachers’ perception of examples and how they could be used in the process of teaching a concept. The research method employed in this study was a qualitative survey method. The research population consisted of all high school math teachers of Markazi province in the academic year 89-90 and 75 randomly selected teachers participated as the sample. The results showed that teachers are aware of the necessity of the use of examples, but they do not have sufficient knowledge of educational examples and their example space is not sufficiently developed. Most of the teachers consider examples as useful and necessary tool and as a common understandable language for learners. But it seems that they do not consider theorems, problems, definitions, proofs and reasoning as examples. Teachers pointed out some characteristics for educational examples such as clarity and simplicity, math accuracy, being in accordance with students’ learning ability and being measurable, but a large number of them neglected important characteristics such as generalizability, the availability and richness and power of a math example. Findings also indicated that most of participating teachers used examples in parts of teaching process such as conceptualizing or teaching procedures.

Identifying the constraining factors of production and yield gap is very important. Therefore; this research was performed to identify the production constraining factors of local rice cultivars. All management practices from nursery preparation to harvesting stages for 100 paddy fields of local rice cultivars were recorded through field studies, in Sari, from 2015-2016. In the CPA, the actual and calculated potential yield were 4495 and 5703 kg/ha, respectively and the gap was 1221 kg/ha. The yield gap caused by number of top-dressing variables was 324 kg/ha, equal to 27% of the total yield gap. The yield gap related to previous year of legumes cultivation was 218 kg ha-1, equal to 18% of the total yield variation. Among the 10 variables entered in the CPA model, the effects of top-dress fertilizer application and its application frequency and foliar application were remarkable, which could compensate a significant part of the yield gap (444 kg/ha, 37% of total) in the farmers’ fields by managing these variables. According to boundary line analysis (BLA) finding, actual yield mean on the basis of optimal limit related to 12 variables under study was 5369 kg/ha, with 881 kg/ha yield gap . Mean relative yield and relative yield gap for 12 variables (transplanting date, seedling age, number of seedlings per hill, planting density, nitrogen and phosphorous per hectare, nitrogen before transplanting, harvesting date, lodging problem, pest problem, diseases problem and weeds problem) were 83.64 and 16.35 kg/ha, respectively. Based on the finding, it can be stated that the model precision is appropriate and can be applied for both estimation of the quantity of yield gap and determining the portion of each restricting yield variables.

Estimates of technical inefficiency in agricultural production are suspect so long as variations exist in production technology among the sampled farmers. Traditional methods of dealing with these technological differences risk attributing "technology gaps" to technical inefficiency between farms, pointing to the need to undertake a metafrontier analysis that allows technology gaps to be distinguished from technical inefficiency. Using farm-level data on the production of three different varieties of pistachio trees in Iran, we outline two criteria to justify its use: an inability in farmers to switch between production technologies except in the long term, and satisfaction of statistical tests on metafrontier coefficients. The application of metafrontier analysis enabled technical efficiency scores to be corrected for differences in production capacity imposed by tree variety. Results reveal that there is very little difference in technical efficiency between farms growing the different tree varieties. But they show that ignoring the production constraints imposed by variety choice could overstate the scope for farmers to improve their technical performance by adopting better farming practices. The results also indicate that it is misleading to compare the performance of different tree varieties on the basis of yield per hectare alone.

The lack of Quranic approaches in the production of Quran-based humanities is still felt, despite the predominance of the philosophical approach in critical approaches to modern humanities, which has become very common in the Islamic world and in Iran for several decades. It seems that the capacity of the method of thematic exegesis (al-Tafsīr al-mawdū'ī, Arabic: التفسیر الموضوعیّ) in this regard, can be used to bring the Holy Quran into the field of humanities. Thematic exegesis, according to whether its subject is inside or outside the Qur'an, has several functions in criticizing the structure of modern knowledge and scientific research, as well as the production of Islamic humanities. It is possible to make use of thematic exegesis of the inside of the Holy Book of Quran in order to “fundamental criticism” of the general fundamentals of humanities -the fundamentals of epistemology, axiology, ontology and anthropology- and it is also possible to use thematic exegesis for constructing and producing foundation of humanities obtained from the Holy Quran. It is used by thematic interpretation exegesis of the outside of the Holy Book of Quran -such as Shahīd (martyr) Sadr’s interrogational approach- to answer the problems of humanities and this process faces challenges such as the complexity and multiplicity of the “subject” of the humanities that exist in modern terminology of this field. It can be used in order to solve this issue in some cases to know the process of the change of the components of the modern of the conceptual history’s approach and also by analyzing the issue into several components can be shown that the components are not necessarily a product of the modern era and can be followed up in the Holy Quran and can be found up in the Holy Quran. The perspective of the Holy Quran, after that, regarding the modern subject in the desired field by the “combining” of the results obtained based on the thematic interpretation.

This study was conducted during summer and winter of 2018- 2019 in the agricultural research field of Shahid Chamran University. Experimental design was split- plot based on RCBD with three replications. The main plot was the type of agricultural system in three levels including conventional (Conv), organic (Org) and sustainable (Sust) (integrated between Conv and Org) and sup- plot was the type of pre- cultivated crop in sequence with wheat including cultivation of mung bean (M- W), corn (C- W), sesame (S- W) and fallow (F- W). Yield quantity (yield and its component) and quality (grain protein), an estimate of photosynthesis matter transfer index of wheat and soil organic carbon (SOC) after one double-cropping were measured. The result showed that the highest (545.04 g/m2) and the lowest (409.28 g/m2) seed yields were obtained in Conv and Org respectively. In contract, with the changing type of system from Conv to Org, grain protein was increased significantly (from 8.3 to 9.6 %). In addition, the highest (535.47 g/m2) yield of wheat was obtained from M- W double cropping. On the other hands the highest remobilization and current photosynthesis matter were obtained in the organic agricultural system with M- W and conventional with M- W double cropping. The situation of SOC showed that the highest (33.18 mg/g) SOC was obtained in the organic agricultural system with C- W double cropping. The reason for improving SOC in the organic and sustainable agricultural system was application of organic matter (compost and vermicompost) and crop residue management. Totally, from the crop ecology point of view, sustainable agricultural method with a sequence of M- W was the most desirable system.

Medicinal plants contain active ingredients in one or some of their organs. Squalene is one of the active ingredients that prevent heart attacks and cardiovascular diseases and protect the body from some cancers. The aim of the present study was to investigate the presence of squalene in a number of medicinal plants. In this experiment, the plant oils were extracted and measured using Bligh & Dyer with minor changes. TLC (thin layer chromatography) was used to identify squalene. Comparison of TLC of standard squalene with TLC of the investigated medicinal plant samples showed that Caryophillium aromaticus, Descurainia sophia, Portulaca Oleracea, Papaver somniferum and Nigella Sativa contained squalene. Although the percentage of Papaver somniferum and Nigella Sativa seed oil was higher than other medicinal plants, the squalane spot of clove plant had a higher intensity of color and this indicates a higher concentration of squalene in this plant.

Two experiments were designed to investigate how students use examples and procedures to solve algebra word problems. In the first study the effect of teaching through example and procedure was investigated on the students algebra word problem solving performance.Participants were 73 girl students in their 3rd year of math-physics branch, secondary school. They were randomly assigned to three groups. The first group was instructed by presenting simple examples,the second group by procedure, whereas the third group was instructed by both procedure and simple example. No significant difference was observed in the performance of the three groups. In Experiment 2, three new conditions consisting of complex example, complex and simple examples,and complex example plus procedure were added to two of the conditions in Study 1, namely simple example condition and procedure condition. The 122 participants in Study 2 had similar characteristics to subjects in the first study. Results indicated that there were statistically significant differences among the five groups. Results show that adding examples at different levels of complexity to procedure improves the capability of students problem solving, which is in harmony with empirical and theoretical background.

In this paper, we investigate pseudo-Riemannian manifolds those eigenvalues of the Weyl conformal Jacobi operators are constant on the unit sphere bundles. Using a result of [4], we give an explicit construction of conformally Osserman manifold which is not locally conformally flat.