Considering the importance of implementing monetary policy in any economy, its impact on the main economic variables, including production, is very crucial. This paper examines and analyzes the effects of positive and negative monetary shocks on production in Iran using the MS-DSGE model during the period of 1979-2004. The results of this study indicate that positive and negative monetary policies in the recession periods, as well as boom periods, have asymmetric effects on the growth of domestic production. The effect of positive and negative monetary shocks on production is higher during the recession than during the boom. Generally, the monetary shocks are more effective during the boom than the recession. Accordingly, it is suggested that to achieve the economic goals policymakers should implement their policies during the economic recessions.

Introduction: When there is no immediate access to dental laboratory for pouring dental impressions, impression materials with dimensional stability over time should be used. The aim of this study was to evaluate the effect of storage time on dimensional stability of casts poured from alginate impressions.Materials and Methods: In this experimental-laboratory study, a metal model containing two dies and acrylic impression trays were used to make five alginate impressions at each time interval using three different alginate brands [Hydrogum 5 (Zhermack), Elastic Cromo (Spofadental), and Alginmax (Major)]. The impressions were kept in a humid environment for 0, 24, 48, 72, and 120 hours and then poured with Type III dental stone. Five dimensions were measured in each cast with a digital caliper: ED (distance between the two dies), H1 (height of the smaller die), H2 (height of the larger die), D1 (diameter of the smaller die), D2 (diameter of the larger die). The results were compared among groups with two-way ANOVA and a post hoc Tukey test (a=0.05).Results: Dimensional stability of alginate impressions was dependent on both the material and time (p value<0.05); however, their reciprocal interaction did not exhibit any significant relationship at the same interval (p value>0.05). After 24 hours, dimensions of Elastic Cromo alginate only did not exhibit any statistically significant differences with the model (p value>0.05). After 48 and 72 hours Hydrogum5 alginate only did not demonstrate any significant dimensional differences with the model (p value>0.05). After 120 hours, Hydrogum5 alginate exhibited a significant difference with the model in H2 dimension.Conclusion: The results showed that Alginmax impressions must be poured immediately. Elastic Cromo impressions can be poured after 24 hours. The impression of these three kinds of impression materials did not exhibit any significant dimensional differences before 120 hours; however, they are not reliable for five-day usage.

This paper introduces Markov-switching (MS) GARCH processes for capturing the skewness in the distribution of financial time series. The model class is motivated by the fact that empirical return distributions characterized by significant asymmetries, but the generic assumption of return distributions is Normal. The out of sample performance of symmetric and asymmetric MS GARCH models is compared in an application to Tehran exchange price index (Tepix). Finally, to put the Regime-switching models into perspective, we add to the list of competitors a popular model which may serve as a benchmark, i.e., the single–regime GARCH (1, 1). It turns out that asymmetric MS GARCH processes perform best overall.

This paper proposes a new variable frequency zero voltage switching (ZVS) control method for boost converter operating in boundary conduction mode (BCM). The intended method keeps the converter in BCM despide of the  load and input voltage variations. This is done by changing switching frequency in a certain specified range. The proposed method can guarantee circuit performance in BCM via zero-crossing detection of the inductor current and changing the switching frequency. In addition, with a slight modification in control structure, it is possible to achieve a fully ZVS in all cases. This converter control is carried out in analog form without using microprocessors which, compared with the digital one, has less noise, cost and processing challenges in high frequency applications. Simulation results obtained from applying the proposed method on a GaN-based synchronous boost converter in two different switching frequency ranges (100KHz and 1MHz) are indicative of the proposed strategy advantages.

We say that a complex number l is an extended eigenvalue of a bounded linear operator TT on a Hilbert space HH if there exists a nonzero bounded linear operator XX acting on HH, called the extended eigenvector associated to l, and satisfying the equation TX=lXT. In this article, we describe the sets of extended eigenvalues and extended eigenvectors for the quasinormal operators.

Price volatility and volatility regime switching of Iranian important livestock markets are modeled using hay, sheep, calf, mutton, and beef monthly return series over the period of April 1992 to March 2014, using Markov-switching generalized autoregressive conditional hetroscedastisity models. The results suggest the existence of two volatility regimes in all studied markets and frequently switching from one regime to another all except for hay. Hay market is the most homogeneous market in terms of volatility regime switching while mutton market is the most variable one. According to results, although the high volatility regime lasts less than low volatility regime, persictency of high volatility regime (at least 5 month) in producer and retailer meat markets and frequently switching from one regime to another lead to uncertainty of investing in meat production. It also leads to unpredictability of market condition and variability of consumer’s welfare.