Effects of heat and drought stress on cereal crops across spatial scales

The production of cereal crops is increasingly influenced by heat and drought stress. Despite the typical small-scale sub-regional variability of these stresses, impacts on yields are also of concern at larger regional to global scales. Crop growth models are the most widely used tools for simulating the effects of heat and drought stress on crop yield. However, the development and application of crop models to simulate heat and drought is still a challenging issue, particularly their application at larger spatial scales. Previous research showed that there is a lack of information regarding the: 1. Response of cereal crops to heat stress, 2. Interactions between phenology and heat stress under climate change, 3. Improvement of crop models for reproducing heat stress effects on crop yield, 4. Upscaling of heat and drought stress effects with crop models, 5. Effects of climate and management interactions on crop yield in semi-arid environments. Five detailed studies were arranged to improve the understanding on the aforementioned gaps of knowledge: 1. A review study was set up to understand how crop growth processes responded to short episodes of high temperature. In addition, the possible ways for improvement of the heat stress simulation algorithms in crop models were investigated at a field scale. The reproductive phase of development in cereals was found to be the most sensitive phase to heat stress. Crop models aiming to model heat stress effects on crops under field conditions should consider the modelling of canopy temperature. This may also provide a mechanistic basis to link heat and drought stress in crop models. Generally, these two stresses occur simultaneously. 2. In a nationwide study, the interactions between the advancements of phenology and heat stress on winter wheat (Triticum aestivum L.) due to global warming, were evaluated between1951-2009 across Germany. The increase in temperature (~1.8°C) shifted crop phenology to cooler parts of the growing season (~14 days) and compensated for the effect of global warming on heat stress intensity in the period 1976-2009. The intensity of heat stress on winter wheat could have increased by up to 59% without any advancement in phenology. 3. A large-scale simulation study was conducted to investigate the effects of input (climate and soil) and output data aggregation on simulated heat and drought stress for winter wheat over the period of 1980-2011 across Germany. Aggregation levels were compared in several steps from 1 km × 1 km to 100 km × 100 km. Simulations were performed with SIMPLACE. Aggregation of weather and soil data showed a slight impact on the mean and median of simulated heat and drought stress at the national scale. No remarkable differences in simulated mean yields of winter wheat were evident for the different resolutions ranging from 1 km × 1 km to 100 km × 100 km across Germany. However, high resolution input data was essential to reproduce spatial variability of heat and drought stress for the more heterogeneous regions. 4. Two regional studies were arranged to evaluate the interactions between management and climate on crop production under climate change conditions. A crop model (DSSAT v4.5) was employed to assess the interactions between fertilization management of pearl millet (Pennisetum americanum L.), crop substitution [pearl millet instead of maize (Zea mays L)], and climate in semi-arid environments of Iran and the Republic of Niger, respectively. The pearl millet biomass production showed a strong response to different fertilization management in Niger. The highest dry matter production of pearl millet was obtained in combination with crop residues and mineral fertilizer treatment. The dry matter production of pearl millet was reduced by 11% to 62% under different climate change scenarios and future time periods (2011-2030 and 2080-2099). Results of this study showed that higher soil fertility could compensate for the negative effects of high temperature on biomass production. This was a result of the strong positive relationship between biomass production and the sum of precipitation under high soil fertility. Crop substitution as an adaptation strategy (new hybrids of pearl millet instead of maize) enhanced fodder production and water use efficiency in present and potential future climatic conditions in northeast Iran. However, the fodder production of both crops was reduced due to shortening of the period from floral initiation to the end of leaf growth under various climate change conditions. Benefits of crop substitution may decline under climate change resulting in higher temperature sensitivity of the new hybrids of pearl millet. Several conclusions were drawn from this study: It is necessary to consider canopy temperature instead of air temperature in crop models and use data from experiments under field conditions to improve and properly calibrate crop models for heat and drought stress responses. Crop models must also consider that effects of heat and drought stress on crops differ with phenological phases and can be compensated for by responses of other processes. An increase in the intensity of heat stress around anthesis can, for instance, be fully compensated for by the advancement in phenology in winter cereals under climate change. It is not necessary to use high resolution weather and soil input data for simulating the effects of heat and drought stress on crop yield at a national scale; but, high resolution input data are necessary to reproduce spatial patterns of heat and drought. Finally, implementation of management practices in cropping systems may change the response of crops to climate change. For this reason, management practices should be considered as an adaptation strategy

STUDYING THE RELATIONSHIP BETWEEN DISCRETIONARY ACCRUALS AND SOME OF THE PERFORMANCE INDICATORS OF COMPANIES LISTED IN TEHRAN STOCK EXCHANGE

The fact of importance of measuring performance is recognized for organizations and it plays an important role in many organizations. Today, as we are in the information age, accounting profit is part of the information used by investors in risk assessment and returns on an accrual basis. The corporate performance evaluation is one of the most important issues for investors in terms of investment decision. The purpose of this study was to study the relationship between the voluntary accruals level and the performance indicators of companies listed in Tehran Stock Exchange. For this purpose, some performance indicators such as cash flow, return on assets, return on equity, price-to-profit ratio, and return on investment were measured. The research sample consisted of 102 Iranian stock exchanges during the years 2010-2014. The results of the research show that there is a significant relationship between discretionary accruals and operating cash flow and equity returns, and the market pricing of accruals is not affected by the external financing levels.  Article visualizations

Emergency response network design for hazardous materials transportation with uncertain demand

Transportation of hazardous materials play an essential role on keeping a friendly environment. Every day, a substantial amount of hazardous materials (hazmats), such as flammable liquids and poisonous gases, need to be transferred prior to consumption or disposal. Such transportation may result in unsuitable events for people and environment. Emergency response network is designed for this reason where specialist responding teams resolve any issue as quickly as possible. This study proposes a new multi-objective model to locate emergency response centers for transporting the hazardous materials. Since many real-world applications are faced with uncertainty in input parameters, the proposed model of this paper also assumes that reference and demand to such centre is subject to uncertainty, where demand is fuzzy random. The resulted problem formulation is modelled as nonlinear non-convex mixed integer programming and we used NSGAII method to solve the resulted problem. The performance of the proposed model is examined with several examples using various probability distribution and they are compared with the performance of other existing method

Implementing a flipped model of instruction in the EFL listening classroom: Impact on comprehension

Inventive technologies have provided students greater ways to invest more productive time within the classrooms, such as listening class. However, the flipped model of instruction should be practiced as a way to engage students in the process of listening comprehension. This experimental study aimed to investigate the effects of the flipped classroom (FC) on advanced EFL learners’ listening comprehension. Sixty Iranian advanced EFL learners (19 to 23 years old) participated in 14 sessions. Half of the students taught through the flipped model of instruction (experimental group) and the others through traditional instruction (control group). Using a before and after design, students were retested after seven weeks. Results showed that the means average resulted from the L2 listening comprehension test revealed those both groups showing increases in listening scores, but the experimental group’s mean score was higher than in the control group. Therefore, the FC model's implementation in the context of teaching and learning L2 listening comprehension can lead to positive outcomes since they could engage students in the process of learning English. The implication of this study calls for the FC model implementation to engage students in listening comprehension in the chance to learn better and expand their educational knowledge

Automatic summarisation of Instagram social network posts Combining semantic and statistical approaches

The proliferation of data and text documents such as articles, web pages, books, social network posts, etc. on the Internet has created a fundamental challenge in various fields of text processing under the title of "automatic text summarisation". Manual processing and summarisation of large volumes of textual data is a very difficult, expensive, time-consuming and impossible process for human users. Text summarisation systems are divided into extractive and abstract categories. In the extractive summarisation method, the final summary of a text document is extracted from the important sentences of the same document without any modification. In this method, it is possible to repeat a series of sentences and to interfere with pronouns. However, in the abstract summarisation method, the final summary of a textual document is extracted from the meaning and significance of the sentences and words of the same document or other documents. Many of the works carried out have used extraction methods or abstracts to summarise the collection of web documents, each of which has advantages and disadvantages in the results obtained in terms of similarity or size. In this work, a crawler has been developed to extract popular text posts from the Instagram social network with appropriate preprocessing, and a set of extraction and abstraction algorithms have been combined to show how each of the abstraction algorithms can be used. Observations made on 820 popular text posts on the social network Instagram show the accuracy (80%) of the proposed system

Prevalence of Color Blindness in Iranian Students: A Meta-analysis

Color blindness (color vision deficiency) is a disorder that impairs the true perception of colors. Using the information in this study, appropriate policy can be made to identify high-risk groups, as well as educational policies for families to perform more effective genetic diagnosis methods. This study aims to examine the prevalence of color blindness in Iranian students through a meta-analysis. Articles related to color blindness published between January 1990 and December 2020 were searched in Scopus, Cochrane Library, Web of Science (WoS), Science Direct, Embase, SID, MagIran, IranDoc, Medline, and Google Scholar databases. The keywords used were based on medical subject topics (MeSH Terms) and, after careful review, articles were selected according to varied sections of Participants, Exposure, Comparison, and Outcomes (PECO). Participants: students; Exposure: students with color blindness were examined; Comparison: Students from multiple provinces and regions of Iran were surveyed for color blindness; Outcomes: the pooled prevalence of color blindness in Iranian students reported from different provinces. The prevalence of color blindness in Iranian students was 3.8% (95% CI: 2.7–5.4%). The pooled prevalence of color blindness in Iranian male and female students was 4.7% (95% CI: 3.5–6.4%) and 0.7% (95% CI: 0.3–1.3%), respectively. The pooled prevalence of red–green color blindness (Tritan) was 41.7% (95% CI: 18.9–68.8%). The pooled prevalence of red color blindness (Protan) was 13.9% (95% CI: 7.8–23.8%), and the pooled prevalence of green color blindness (Deutan) based on meta-analysis was 45.3% (95% CI: 29–62.7%). Due to the high prevalence of color blindness in students, especially male students, it is necessary to be screened for through genetic tests in couples before having children

A cost-utility analysis of different antiviral medicine regimens in patients with chronic hepatitis C virus genotype 1 infection

Background: Despite the introduction of new drug regimens with high effectiveness for the hepatitis C virus (HCV) patients, especially in HCV genotype 1, no cost-effectiveness study on the selection of the superior drug strategy in Iran has been conducted yet. Objectives: This study is aimed to assess the cost-effectiveness of the three drug regimens of pegylated interferon and ribavirin (PR), sofosbuvir (SOF) + PR and ledipasvir and sofosbuvir (LDV/SOF) in patients with HCV genotype 1 in Iran in the year 2014. Methods: A Markov micro-simulation model was used to evaluate the cost-effectiveness of the three drug strategies for a cohort of 10000 patients. Quality-adjusted life-years (QALYs) were extracted from published studies. Cost data was estimated through the review of medical records and obtaining experts opinion. Results: The results showed that the SOF + PR drug compared with PR had a lower cost and was more effective, but compared with the LDV/SOF, in spite of its lower cost, it was less efficient. The QALY values obtained for PR, SOF + PR and LDV/SOF, respectively, were 10.98, 12.08 and 12.28 and their costs were $41,741,$ 7,676 and $46,993. Moreover, the results obtained from acceptability curves showed that SOF + PR were the most cost-effective treatment for thresholds below$ 45,270 PPP. Conclusions: The use of SOF + PR regimen or LDV/SOF can significantly reduce the incidence of complications associated with the disease. For example, short and long-term outcomes are better than the current drug regimens for HCV genotype 1 patients in all stages of the disease