Risk is a concept and phenomenon that will deals with the possibility of danger and the power of harm in the future and belongs to the risks ahead. The approach to risk, in addition to technical and computational evaluation, follows cultural and social patterns. Therefore, it extended to the perceptual and activity aspects of human beings. The present study targeted the mental evaluation of urban dwellers about environmental risks in Tehran from the perspective of informed subjects. This study collected the data by adopting the method of grounded theory and conducting twenty semi-structured interviews of higher education informants during the process of purposeful and theoretical sampling and achieved theoretical saturation and conceptual regulation. Findings indicate that in terms of subjects, urban dwellers in Tehran do not have a significant perception and activity in the face of environmental hazards to the city of Tehran. On the one hand, in their minds, the perception of environmental risks has not been determined much, and on the other hand, action focused on environmental risks does not have a significant presence and even tends to passive actions. Therefore, it can be inferred that there is no internal risk culture among the residents of Tehran and there is no risk discourse in their minds and actions. In the end, the paradigmatic model of perceptual and cognitive retardation of urban dwellers from environmental risks in Tehran has been drawn and interpreted.

This study examines effects of corporate governance mechanisms and audit features on timely disclosure predicted through an audit report lag. This research is an applied and descriptive-correlative one which uses the multivariate regression method and Eviews software to analyze the data. The sample consists of 110 firms listed in Tehran Stock Exchange over the period from 2014 to 2017. The results show a significant negative relation of audit type, the number of corporate business reports, the ratio of independent directors, the size of the board, and the audit committee's activity with the audit report lag; and a significant positive relation between the unqualified audit opinion, extraordinary items, the CEO's duplicity, the ratio of inventory and debt to total assets, and property dispersion with the audit report lag

Abstract We present an exact solution procedure for the weighted earliness-tardiness project scheduling problem (WETPSP) with generalized precedence relations (WETPSP-GPR), taking into account time value of money (WETPSPDC-GPR) and a fixed deadline for the project. The WETPSP-GPR extends the WETPSP to arbitrary minimal and maximal time-lags between the starting and completion times of activities. We present a new depth-first branch and bound (B&B) algorithm for extended form of the problem, which time value of money is taken into account by discounting the cash flows and minimum as well as maximum time-lags between different activities may be given. The algorithm is extended with two bounding rules in order to reduce the size of the branch and bound tree. Finally, some test problems are solved and computational results are reported. Keywords: Project scheduling; Branch and bound; Net present value; generalized precedence relations

Identification of factors affecting hydrological processes plays an important role in water resources management. In this study, the effects of hydrological parameter variations such as rainfall, temperature and runoff time series are prioritized on the groundwater level fluctuations for the Silakhor plain using cross and coherence wavelet transforms. Cross wavelet transform and coherence wavelet transform estimate the interaction and time lag between two time series relatively. These transformations indicate that two time series have depended on period and phase lag. For this purpose, the time series of groundwater level- runoff, groundwater levelrainfall and groundwater level-temperature have entered into the cross wavelet transform and coherence wavelet transform algorithm mutually to determine the effects and interaction between these time series. The results show that runoff time series as the human activity factors with the mean wavelet correlation coefficient estimated as 0.83 is more effective than rainfall and temperature time series whereas the climate change factors are with the mean wavelet correlation coefficients of 0.52 and 0.58, respectively concerning groundwater level decline of the Silakhor plain. Thus, the human activity factors are more effective than the climate factors in declining the groundwater level in this plain.

Economic specialization and diversification in an urban area are main factors forming agglomeration economies. Agglomeration economies increase productivity of clustered firms in an area. This research investigates the impact of specification and diversification in economic activities on labor productivity in the provinces of Iran during 2000-13. Therefore, first, urban economic specification and diversification are measured using appropriate indices. Then, the indices are entered in the productivity model as an independent variable. Since used data has locational dimension and the spatial dependence diagnostic tests are significance, the specified model is estimated through spatial econometric techniques.
The results show in both spatial lag and error, specialization and diversification of economic activities, as well as capital stock and government budget have a significant positive with productivity. But human capital has a U-shaped relationship with productivity. In addition, the estimated coefficients of spatial lag and spatial error are positive and statistically significant and indicate spatial dependence of productivity in the provinces of Iran.

Due to the importance of tax revenues compared to oil revenues in supplying government budget, it is necessary to study tax system efficiency. The decline in real tax revenues is affected by two factors i.e. tax lags and inflexible tax system. If tax Collection Lag is long and the tax system is inflexible, inflation will make the real tax income cut. So, in this study, we tried to use the data from 1380 to 1390 and the cointegration method of Johansen-Juselius to calculate the tax lags and price elasticity of various tax income groups in Golestan province. The results indicate that during the study period, the average tax collection lags were 11 months (companies’ tax lag was 15 months, tax income lag was about 15.3 months, and tax wealth lag was about 2.13 months and the indirect tax lag was about 3/5 months. In other words, the average direct tax collection lags were 79/10 months (11 months). However, during the study period, indirect taxes collection lags were 5.32 months which is less than the direct tax collection lags.

In the past three decades, Tehran has experienced warmer summer so we need to determine heat-related mortality to establish appropriate public health activities during hot summers. The aim of the present study was to detect heat waves during the last decades and then determine excess mortality in immediate and lagged times. An ecological study based on time-series model was conducted in Tehran for recent decade using generalized linear lagged model (GLLM) with Poisson regression. Maximum daily temperature was heat exposure for death outcome on the same day (lag 0), 3 (lag01) and also 7 (lag02) -day moving average. Relative risk with 95% confidence was reported to quantify for increasing of daily mortalities for 1°C risen exposure. Air pollutants considered as confounders in final model. Total excess mortality during 17 heat waves was 1069 (8.9 deaths/Heat wave days). All non-external cause of death increased significantly during heat waves (3-9%) and after adjusting for ozone and PM10, raised. Cause-specific deaths (especially circulatory disease) and death among elderly increased during heat waves (especially in the hottest wave). The largest positive lagged effect of hot temperature although seen during hottest waves for all mortalities. Three waves had the most harvest effect for all categories of mortalities. Study showed excess mortalities resulted from hot temperatures and exacerbated with air pollutants in Tehran in the context of climate change. Forward displacement mortality and lagged mortalities as well as were seen, but our results were not conclusive about the displacement pattern of mortalities.

Accruals, as a criterion for measuring earnings management, play a major role in today studies. In fact, earnings management detection is the main usage of accruals segregation. A number of models are employed to determine earnings management of which Jones and Modified Jones models are known to be the best.
In this study, we investigate the inclusion of three proposed variables in the above-mentioned models and their possible contribution to error reduction and consequent optimization of the models. These variables include current and lagged operating cash flows, lagged cash flows, and concurrent current and lagged operating cash flows and lagged cash flows.
The results show that adding our proposed variables by the following can improve the efficiency of our models in earnings management detection:1. Concurrent, current and lagged operating cash flows and lagged cash flows.
2. Current and lagged operating cash flows,
3. Lagged accruals.

The recent economic growth theories believe that the inovation developed in response to economic incentives is the main engine of technological progress and economic growth traditionally. Thus this study investigates the role of capital and R&D activities in Iran, Turkey and Malaysia with distributed lag regression during 1981-2012. The result indicates that in the long term, in Malaysia, impact of R&D activities, is sustainable and more stable on economic growth in comparison with Iran and Turkey. Also the R&D investment compared with physical capital has a greater impacton economic growth inTurkey and Iran.

The goal of this study is to appraise the ability of two variables, operating cash flows and accruals in predicting operating cash flows and Operating Profit with time lags. The study period is from 2005 to 2010. The regression results for hypothesizes show that there is a significant relationship between future operating cash flows and cash component of Operating Profit, and current year shows the highest relationship in relation to all the lags. Also, the results reveal that, there is a significant relationship between future operating cash flows and accrual component of Operating Profit, and two years lags show the highest relationship in relation to other lags and current year. Furthermore, The results indicate that there is a significant relationship between future Operating Profit and, cash and accrual components, and four years lags show the highest relationship in relation to other time lags and current year. So, recording to this research, the best predicting of Operating Profit and Operating Cash Flows will be received on these time lags.