Background and Aims: Lasers with different characteristics have been used to stimulate orthodontic tooth movement. Considering the contradictory findings in this regard, this study was designed to assess the effect of low level laser therapy (LLLT) on the rate of orthodontic tooth movement.Materials and Methods: In this randomized clinical trial study, 12 patients (4 boys and 8 girls; average age: 16.9±3.4) with extracted upper first premolars and required canine retraction into extraction site were included. While in both sides canines were retracted by NiTi coil spring, one side was exposed to GaAlAs laser (890 nm). LLLT was done (on the buccal and palatal mucosa by slow movement of probe) at the beginning of the first month. Impression and cast fabrication performed at the beginning of retraction, one and two months later. The amount of retraction on the cast was measured with the aid of a reference plaque fabricated on the rogae using a digital caliper. Data were analyzed using paired sample T-test and one-sample Kolmogorov-Simirnov test.Results: There was no significant difference in the amounts of canine movement between laser exposed and control sides (P>0.05).Conclusion: The energy dose of laser used in this study (72 J per each tooth) was not appropriate for increasing dental movement.

In order to properly understand the subsurface structures, the issue of inversion of geophysical data has received much attention from researchers. Since accurate reconstruction of the shape and boundaries of the mass using gravimetric data is very important in some issues, it is important to use an effective and efficient method that has a high ability to draw and reconstruct the boundaries of a mass. In recent years, the level set method introduced by Asher and Stein has been widely used to solve this problem. From the expansion of the level set function in some bases of the problem, the effective number of parameters is greatly reduced and an optimization problem is created which its behavior is better than the least squares problem. As a result, the level set parameterization method will be presented for the reconstruction of inversion models. A common advantage of the parametric level set method is the careful examination of the boundary for optimum sensitivities, which significantly reduces the dimensional problem, and many of the difficulties of traditional level set methods, such as regularization, reconstruction, and basis function. Level set parameterization is performed by radial basis functions (RBF),which causes an optimal problem with an average number of parameters and high flexibility,and the computational and optimization process for Newton's method is more accurate and smooth. The model is described by the zero contour of a level-set function, which in turn is represented by a relatively small number of radial basis functions. This formulation includes some additional parameters such as the width of the radial basis functions and the smoothness of the Heaviside function. The latter is of particular importance as it controls the sensitivity to changes in the model. In this algorithm adaptively chooses the required smoothness parameter and tests the method on a suite of idealized Earth models. In this evolutionary approach, the reduction gradient method usually requires many iterations for convergence, and the functions are weakened for low-sensitivity problems. Although the use of Quasi-Newton methods to improve the level set function increases the degree of convergence, they are computationally challenging, and for large problems and relatively finer grids, a system of equations must be solved in each iteration. Moreover, based on the fact that the number of underlying parameters in a parametric approach is usually much less than the number of pixels resulting from the discretization of the level set function, we make a use of a Newton-type method to solve the underlying optimization problem. In this research, the algorithm is used to investigate its strengths and weaknesses for applying geophysical gravity data, coding and programming, and it is tested using several two-dimensional synthetic models. Finally, the method is tested on gravity data from the Mobrun ore body, north east of Noranda, Quebec, Canada. The results of this study show that the application of the optimization algorithm of the level set function will lead to a relatively more accurate and realistic detection of mass boundaries. It shows that the tested mass has spread from a depth of 10 meters to a depth of 160 meters.

Background and Aims: Lasers with different characteristics have been used to stimulate orthodontic tooth movements and to inhibit the pain during tooth movements. Considering the contradictory finding in this respect, the effect of low level laser therapy (LLLT) was evaluated on the pain during orthodontic tooth movement.Materials and Methods: In this randomized clinical trial study, 12 patients were included with extracted upper first premolars and required canine retraction into extraction site. While in both sides canines were retracted by Niti coil spring, one side was exposed to GaAlAs laser (890 nm). LLLT was done on the buccal and palatal mucosa by slow movement of probe. The patients were asked about their pain on both sides 2 days after beginning of retraction. Pain measurement was evaluated with VAS.Results: Pain perception in LLLT side was significantly decreased (P=0.007).Conclusion: Based on the results, single irradiation of GaAlAs laser (12 J energy per tooth) can decrease pain perception.

In this research, fluctuations of water level at the mouths of Arvandrud and Bahmanshir rivers are studied. COHERENS which is a three-dimensional hydrodynamic model is employed to simulate salinity and temperature in three dimensions. In this model, Cartesian coordinate for the horizontal and sigma coordinate with three layers is used for the vertical profile. At open boundaries variations of salinity, temperature as well as four main tidal constituents (M2, S2, O1, and K1) are applied. Monthly mean atmospheric parameters (speed and wind direction, temperature, rainfall, relative humidity and cloud coverage) are also employed in the model. In this study, uniform grid of 491×690 is used which covers the region of 40×55 square kilometers of both Arvandrud and Bahmanshir estuaries. In order to validate the results of the model, outputs of the model are compared whit confirmed Admirality Tide Tables and found a very good agreement between them. To compare water level fluctuations of Arvandrud River with Bahmanshir River, some stations were selected along rivers with equal distances from the river mouths. Results of this comparison show that, the speed of tidal wave at Arvandrud River is higher than Bahmanshir River. Also tidal range in the Bahmanshir River found lower than Arvandrud River.

The main purpose of this study is to explore the factors affecting Urmia Lake water level variations. Urmia Lake water level, rainfall, temperature, river discharge, and groundwater level data were used to study the relationship between the Urmia Lake water level variations and climatic and hydrologic parameters. Urmia Lake water level data for 48 years (1965 to 2013) from 27 synoptic meteorology stations of Tabriz, Urmia, and Saqez were used for the rainfall and temperature variables. Also, for adjusting the groundwater level data, of the 1054 wells, 123 wells with complete data in the studied period were selected. The non-parametric run test was used to determine the homogeneity and randomness of the data and the probability of any trend in time series. The randomness of the variables was examined at an error probability of 0. 05 and their homogeneity was assured. The Mann-Kendall test was used to study trends, leaps, and changes in the independent variables including precipitation, temperature, river discharge, and water table of wells. A review of the Mann-Kendall curves showed that the average annual temperature changes during the study period do not follow a meaningful trend. The Urmia Lake Basin Annual Precipitation Curve showed a decreasing trend in the 48 years. The review of the discharge rate variations showed that the discharge variations from 1965 to 2013 had a significant and downward trend with a leap from the beginning of the statistical period. The water table variations of observation wells followed a significant downward trend in 2006. The results of Pearson correlation test showed that there is a relatively strong correlation between the independent variables (temperature, precipitation, river discharge, and water table) and lake water level variations (p<0. 05), indicating the validity and the robustness of the linear relationship between the water level and the extent to which this variable is affected by the independent variables.

Introduction: Aquifers are the major source of freshwater in many parts of the world. Saltwater intrusion )SWI) is a serious environmental issue since 80% of the world’ s population live along the coast and utilize local aquifers for their water supply. Globally, coastal aquifers are under threat from saltwater intrusion (SWI). SWI is caused by changes in coastal aquifer conditions resulting from ground water extraction, climate drivers, sea-level rise, oceanic over topping events, and land use change. Under natural conditions, these coastal aquifers are recharged by rainfall events, and the regional groundwater flow towards the ocean counters the intrusion of saltwater into the freshwater region. However, over-exploitation of coastal aquifers in some regions has resulted in a reduction in fresh groundwater levels (and hence reduced natural flow) and this has led to an increase in saltwater intrusion. Saltwater intrusion degrades the quality of coastal aquifer groundwater resource which can lead to a reduction in crop yield efficiency, limitation on the drinking water resource as well as soil fertility and salinity of operated wells. Such problems are more crucial where groundwater aquifers are shallow. Materials and Methods: The aim of this study is to investigate the effect of Lake Urmia water-level fluctuations on groundwater table and rate of the intruding or receding of salt water to the coastal aquifer. In order to achieve this purpose, Rashakan coastal aquifer in the vicinity of Lake Urmia in the northwest of Iran was simulated. In this study, SEAWAT model was used to simulate the problem. SEAWAT was specifically designed for the simulation of SI, although it has many other applications as well, notably the combined simulation of groundwater flow and heat transfer. SEAWAT as a widely used, three-dimensional variabledensity groundwater flow and transport model has been developed by the USGS based on MODFLOW and MT3DMS and includes two additional packages: Variable-Density Flow (VDF) and Viscosity (VSC). First, the model was calibrated and then the simulations were defined in four scenarios as follows: a) The rate of the intruding or receding of salt water to the coastal aquifer during recent years b) The effect of the drop-in lake water level on groundwater level changes trend regardless of changes in lake water density c) The effect of the drop-in lake water level on groundwater level changes trend in view of changes in lake water density d) The effect of the drop-in lake water level on the rate of the intruding or receding of salt water. Results and Discussion: In this study, simulations were carried out under four scenarios in order to investigate the effect of Lake Urmia water-level fluctuations on groundwater table and rate of the intruding or receding of salt water to the coastal aquifer. In the first scenario, in order to assess the rate of the intruding or receding of salt water to the coastal aquifer in recent years, three profiles have been investigated in the north and the center and south of the study area, and the results showed that in recent years there has been no significant change in the displacement of the salt-water wedge and this change was less than 50 meters and only the upper part of wedge connected to the lake was more affected by dropping water level of lake, which was due to retreat of the boundary imposed by lake water recession. In the second scenario, the effect of the drop-in lake water level on groundwater level changes trend, regardless of changes in lake water density, was investigated. The findings of the study showed that if the concentration of lake water is considered constant, the increase and decrease in groundwater level across the aquifer would be almost equal to the increase and decrease the lake water level. In the third scenario, the effect of the drop-in lake water level on groundwater level changes trend in view of changes in lake water density was investigated and the findings was also made with the second scenario, where the results showed that when the effect of the density changes is neglected, the groundwater level is affected by the lake water level changes more than about 2 times that when the density changes are considered. However, increasing and decreasing concentrations, and consequently increasing and decreasing the density, may have a great effect on the reduction and increase of groundwater levels. In the fourth scenario, the effect of the drop-in lake water level on the rate of the intruding or receding of salt water was also investigated. It can be concluded that when concentration changes and as a result of variations in density are affected, by decreasing the level of the lake, saltwater wedge would be intruded and when the effect of the density changes is neglected, saltwater wedge would be receded. Conclusion: The results of this study indicated that during recent years there has been no significant change in the location of the salt water wedge, and this change is less than 50 meters. The upper part of wedge connected to the lake is more affected by dropping water level of lake, which is due to retreat of the boundary imposed by lake water recession. Also, the findings of the study showed that if the concentration of lake water is considered constant, the increase and decrease in groundwater level across the aquifer will be almost equal to the increase and decrease of the lake water level. When the effect of the density changes is neglected, the groundwater level is affected by the lake water level changes more than by about 2 times that when the density changes are considered. Despite the decreasing of about 7 meters of lake Urmia water level, due to increase the density of water, the wedge has intruded. This research shows that in the event of an increase in the water level of Lake and consequently a decrease in water density, Saltwater wedge would be receded.