Oroclinal bending, distributed thrust and strike-slip faulting, and the accommodation of Arabia–Eurasia convergence in NE Iran since the Oligocene

Regional shortening is accommodated across NE Iran in response to the collision of Arabia with Eurasia. We examine how N–S shortening is achieved on major thrust systems bounding the eastern branch of the Alborz (east of 57°E), Sabzevar and Kuh-e-Sorkh mountain ranges, which lie south of the Kopeh Dagh mountains in NE Iran. Although these ranges have experienced relatively few large earthquakes over the last 50 yr, they have been subject to a number of devastating historical events at Neyshabur, Esfarayen and Sabzevar. A significant change in the tectonics of the eastern Alborz occurs directly south of the Central Kopeh Dagh, near 57°E. To the east, shortening occurs on major thrust faults which bound the southern margin of the range, resulting in significant crustal thickening, and forming peaks up to 3000 m high. Active shortening dies out eastward into Afghanistan, which is thought to belong to stable Eurasia. The rate of shortening across thrust faults bounding the south side of the eastern Alborz north of Neyshabur is determined using optically stimulated luminescence dating of displaced river deposits, and is likely to be 0.4–1.7 mm yr^(−1). Shortening across the Sabzevar range 150 km west of Neyshabur has previously been determined at 0.4–0.6 mm yr^(−1), although reassessment of the rate here suggests it may be as high as 1 mm yr^(−1). Migration of thrust faulting into foreland basins is common across NE Iran, especially in the Esfarayen region near 57°E, where the northward deflection of the East Alborz range reaches a maximum of 200 ± 20 km (from its presumed linear E–W strike at the beginning of the Oligocene). West of 57°E, the tectonics of the Alborz are affected by the westward motion of the South Caspian region, which results in the partitioning of shortening onto separate thrust and left-lateral strike-slip faults north and south of the range. At the longitude of 59°E, published GPS velocities indicate that 50 per cent of the overall shortening across NE Iran is accommodated in the Kopeh Dagh. The remaining 50 per cent regional shortening must therefore be accommodated south of the Kopeh Dagh, in the eastern Alborz and Kuh-e-Sorkh ranges. Assuming present day rates of slip and the fault kinematics are representative of the Late Cenozoic deformation in NE Iran, the total 200 ± 20 km N–S shortening across the eastern Alborz and Kopeh Dagh mountains since the beginning of uplift of the Kopeh Dagh basin would be accommodated in 30 ± 8 Ma. Although this extrapolation may be inappropriate over such a long timescale, the age is nevertheless consistent with geological estimates of post Early-to-Middle Oligocene (<30 Ma) for the onset of Kopeh Dagh uplift

Thermoelectric-coupled hydrodynamic cavitation energy harvesting system

The ever growing energy demand has led to the advent of different energy harvesting systems. This study investigates the performance of a thermoelectric coupled hydrodynamic cavitation system as an energy harvesting device. The effect of changing the working fluid from water to Titania-water nanofluid on the heat generation of the cavitation system is discussed in this study and also the coupling of the cavitation system with one of the micro thermoelectric generators in the literature is included. At the end, the device performance is quantified by comparing its power generation with the required power for the daily used miniature electrical devices

Evaluation of the Degenerative Changes of the Distal Intervertebral Discs after Internal Fixation Surgery in Adolescent Idiopathic Scoliosis

Study Design Retrospective study. Purpose Lumbar intervertebral disc degeneration is an important cause of low back pain. Overview of Literature Spinal fusion is often reported to have a good course for adolescent idiopathic scoliosis (AIS). However, many studies have reported that adjacent segment degeneration is accelerated after lumbar spinal fusion. Radiography is a simple method used to evaluate the orientation of the vertebral column. magnetic resonance imaging (MRI) is the method most often used to specifically evaluate intervertebral disc degeneration. The Pfirrmann classification is a well-known method used to evaluate degenerative lumbar disease. After spinal fusion, an increase in stress, excess mobility, increased intra-disc pressure, and posterior displacement of the axis of motion have been observed in the adjacent segments. Methods we retrospectively secured and analyzed the data of 15 patients (four boys and 11 girls) with AIS who underwent a spinal fusion surgery. We studied the full-length view of the spine (anterior-posterior and lateral) from the X-ray and MRI obtained from all patients before surgery. Postoperatively, another full-length spine X-ray and lumbosacral MRI were obtained from all participants. Then, pelvic tilt, sacral slope, curve correction, and fused and free segments before and after surgery were calculated based on X-ray studies. MRI images were used to estimate the degree to which intervertebral discs were degenerated using Pfirrmann grading system. Pfirrmann grade before and after surgery were compared with Wilcoxon signed rank test. While analyzing the contribution of potential risk factors for the post-spinal fusion Pfirrmann grade of disc degeneration, we used generalized linear models with robust standard error estimates to account for intraclass correlation that may have been present between discs of the same patient. Results The mean age of the participant was 14 years, and the mean curvature before and after surgery were 67.8 and 23.8, respectively (p<0.05). During the median follow-up of 5 years, the mean degree of the disc degeneration significantly increased in all patients after surgery (p<0.05) with a Pfirrmann grade of 1 and 2.8 in the L2–L3 before and after surgery, respectively. The corresponding figures at L3–L4, L4–L5, and L5–S1 levels were 1.28 and 2.43, 1.07 and 2.35, and 1 and 2.33, respectively. The lower was the number of free discs below the fusion level, the higher was the Pfirrmann grade of degeneration (p<0.001). Conversely, the higher was the number of the discs fused together, the higher was the Pfirrmann grade. Conclusions we observed that the disc degeneration aggravated after spinal fusion for scoliosis. While the degree of degeneration as measured by Pfirrmann grade was directly correlated by the number of fused segments, it was negatively correlated with the number of discs that remained free below the lowermost level of the fusion

A New Modified Method for Inserting Iliosacral Screw versus the Conventional Method

Study DesignMethodological study.PurposeTo our knowledge, this is the first study to introduce a new modified method for inserting iliosacral screws and to compare its results with those of a conventional method.Overview of LiteraturePrevious techniques, such as open reduction and internal fixation, are associated with perioperative hemorrhage, postoperative infection, and neurological deficits. Although percutaneous iliosacral screw insertion confers the advantage of being minimally invasive, leading to less blood loss and a low postoperative infection rate, it harbors the risk of screw malpositioning due to narrow sacral proportions and a high interindividual variability.MethodsNine cadaveric pelvises were included in this study, with one hemipelvis of each being assigned to the new modified method and the other to the conventional iliosacral screw insertion method. In the new modified method, the guidewire entry point was determined using a lateral sacral X-ray. To do so, we first identified the anterosuperior quadrant of the S1 body on one hemipelvis. The anterosuperior quadrant was further divided into four imaginary quadrants, and the guidewire was inserted into the posteroinferior quadrant. The guidewire trajectory was perpendicular to the sagittal plane so that the guidewire resembled a single point in the lateral sacral view. Guidewires were inserted into corresponding hemipelves using the conventional method as described in the literature. Subsequently, an axial computed tomography scan with 1-mm fine cuts was obtained, and sagittal and coronal views were reconstructed. The distance of the guidewire from the sacral canal, anterior sacral cortex, and first sacral foramen was measured in axial, sagittal, and coronal views. The minimum measurement among different views was defined as the safety index of the insertion methods. The conventional and new modified methods were then compared in terms of safety and duration of the procedure.ResultsThe minimum distance of the guidewire from the S1 foramen and anterior sacral cortex was not significantly different between the two methods. However, the minimum distance between the guidewire and sacral canal was significantly greater in the new modified method than in the conventional method. The duration of guidewire insertion was significantly shorter in the new modified method than in the conventional method.ConclusionsThis new modified method of iliosacral screw insertion could be safely and simply implemented while taking less surgical time than the conventional methods

Microseismicity and seismotectonics of the South Caspian Lowlands, NE Iran

This paper is concerned with the microseismicity and seismotectonics of the eastern South Caspian Sea region, where the East Alborz mountains descend to meet the South Caspian Lowlands of NE Iran. To better understand the present-day tectonics and seismicity of this region, which includes the cities of Gorgan and Gonbad-e-Qabus (combined population 500 000), we installed a temporary local seismic network across the area for 6 months between 2009 and 2010. We analysed the seismicity and focal mechanisms together with data from the permanent networks of the Institute of Geophysics, University of Tehran (IGUT) and the International Institute of Earthquake Engineering and Seismology (IIEES), based in Tehran. Microseismicity is focused primarily on the Shahrud fault system, which bounds the east Alborz range to the south. Relatively few earthquakes are associated with the Khazar thrust fault, which bounds the north side of the range. A cluster of shallow microseismicity (<15 km depth) occurs 40 km north of the Khazar fault (within the South Caspian Lowlands; SCL), an area typically thought to be non-deforming. This area coincides with the location of three relatively deep thrust earthquakes (M_w 5.3–5.5) which occurred in 1999, 2004 and 2005. Inversion of teleseismic body waveforms allows us to constrain the depth of these earthquakes at 26–29 km. Although significant sedimentation throughout the SCL obscures any expression of recent fault activity at the surface, focal mechanisms of well-located events from the shallow cluster of micro-seismicity show a significant component of left-lateral strike-slip motion (assuming slip occurs on NE–SW fault planes, typical of active faults in the region), as well as a small normal component. Inversion of traveltimes for well-located events in our network yields a velocity structure for the region, and a Moho depth of 41 km. The pattern of deep thrust and shallow normal seismicity could be explained by bending of the rigid South Caspian crust as it underthrusts the East Alborz mountains and Central Iran. Late Quaternary reorganization of drainage systems in the SCL may be the result of shallow normal fault activity within the SCL

The 2012 August 11 Ahar earthquakes: consequences for tectonics and earthquake hazard in the Turkish-Iranian Plateau

We have examined the faulting in the 2012 August 11 Mw 6.4 and 6.3 Ahar (NW Iran) earthquakes using a combination of field mapping, remote-sensing observations of tectonic geomorphology, the cross-correlation of optical satellite images and the inversion of seismic waveforms. The first event was close to pure strike-slip, and the second was an oblique combination of thrust and strike-slip motion. Mapped surface ruptures indicate at least one of these events accommodated mostly right-lateral strike-slip motion on an ∼E–W striking plane. The occurrence of these earthquakes highlights the spatially distributed deformation in NW Iran, which has implications for both hazard assessment (the Ahar events killed over 300 people and injured over 3000), and also tectonic models of the region. Furthermore, these earthquakes demonstrate that the tectonics of the Ahar area is characterized by strike-slip faulting and a component of shortening, and not the previously suggested extension

Renewable Energy, Infrastructure and GHG Implication of Electrified Transportation: Metro Vancouver Case Study

This study is aimed to assess the fleet composition for the new portion of light and medium duty vehicles (LMDV) in Metro Vancouver forecasted for the year 2020. Accordingly, the analysis evaluates the sensitivity of the regional electricity demand on transportation electrification policies. Considering electricity and hydrogen as transportation infrastructures, sixteen scenarios of zero tailpipe emission Electric Vehicle (EV) penetration in the new fleet are investigated. The study assesses the efficiency of EV technologies, quantifies energy demand for the electric transportation, and summarizes the implications of using renewable electricity to power the transportation sector.The analysis shows that wind energy is the superior resource in terms of life cycle Greenhouse Gases (GHGs). The life cycle GHGs of electricity production via wind turbines ranges from 390-3000 tonnes yr- 1 and for photovoltaic cells from 1300-9900 tonnes yr-1 of CO2eq across the scenarios. Furthermore, it is observed that 92% to 96% of life cycle greenhouse emissions could be reduced by deploying zero emission vehicles, which utilize solar or wind energy as a renewable resource. In this category, battery electric vehicles enable larger energy efficiency. Moreover, the results show that in order to respond to FCEV demand by 2020, the number of on-site hydrogen refueling stations should vary between 3 and 62, across different scenarios. The electricity demand to power these stations ranges from 32 to 248 GWh yr-1 which translates to annual production of 5 to 37 wind turbines with 2.24 MW of rated capacity, or alternatively 0.2 to 1.6 km2 of photovoltaic cell surface

Renewable Energy, Infrastructure and GHG Implication of Electrified Transportation: Metro Vancouver Case Study

This study is aimed to assess the fleet composition for the new portion of light and medium duty vehicles (LMDV) in Metro Vancouver forecasted for the year 2020. Accordingly, the analysis evaluates the sensitivity of the regional electricity demand on transportation electrification policies. Considering electricity and hydrogen as transportation infrastructures, sixteen scenarios of zero tailpipe emission Electric Vehicle (EV) penetration in the new fleet are investigated. The study assesses the efficiency of EV technologies, quantifies energy demand for the electric transportation, and summarizes the implications of using renewable electricity to power the transportation sector.The analysis shows that wind energy is the superior resource in terms of life cycle Greenhouse Gases (GHGs). The life cycle GHGs of electricity production via wind turbines ranges from 390-3000 tonnes yr- 1 and for photovoltaic cells from 1300-9900 tonnes yr-1 of CO2eq across the scenarios. Furthermore, it is observed that 92% to 96% of life cycle greenhouse emissions could be reduced by deploying zero emission vehicles, which utilize solar or wind energy as a renewable resource. In this category, battery electric vehicles enable larger energy efficiency. Moreover, the results show that in order to respond to FCEV demand by 2020, the number of on-site hydrogen refueling stations should vary between 3 and 62, across different scenarios. The electricity demand to power these stations ranges from 32 to 248 GWh yr-1 which translates to annual production of 5 to 37 wind turbines with 2.24 MW of rated capacity, or alternatively 0.2 to 1.6 km2 of photovoltaic cell surface