741 research outputs found
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Bilateral Simultaneous Anterior Cruciate Ligament Injury: A Case Report and National Survey of Orthopedic Surgeon Management Preference
Unilateral anterior cruciate ligament (ACL) tear is a common injury seen by sports medicine orthopedic surgeons. However, a bilateral simultaneous ACL injury is extremely rare and has been reported only three times in the literature. We present a young female skier with simultaneous bilateral ACL tears that were managed with staged ACL reconstruction. We then conducted a nationwide survey (United States) to determine the prevalence of simultaneous bilateral ACL tear and preferred management strategies by sports medicine orthopedic surgeons. Sports medicine fellowship directors were contacted and asked to send an 8-item survey to colleagues (sports medicine fellowship trained surgeons) asking about overall number of ACL reconstructions performed, number of bilateral simultaneous ACL injuries seen and optimal management strategies of such an injury. Out of 43 responses, only 22 (51.2%) surgeons had seen a bilateral simultaneous ACL injury. Of these, 16 (76.2%) preferred staged reconstruction. Graft choice was mixed between autograft and allograft, but a large majority preferred either patellar tendon autograft (58%) or hamstring autograft (41%) were the most common choice. Staged reconstruction is the treatment of choice by surgeons surveyed in our study
U-Pb Geochronology, Sr–Nd Geochemistry, Petrogenesis and Tectonic Setting of Gandab Volcanic Rocks, Northeast Iran
This paper addresses U-Pb geochronology, Sr-Nd geochemistry, petrogenesis and tectonic
setting in the Gandab volcanic rocks. The Gandab volcanic rocks belong to the Sabzevar zone magmatic
arc (northeastern Iran). Petrographically, all the studied volcanic rocks indicate porphyritic textures with phenocrysts of plagioclase, K-feldespar, hornblende, pyroxene, and magnetite which are embedded in a fine to medium grained groundmass. As well, amygdaloidal, and poikilitic textures are
seen in some rocks. The standard chemical classifications show that the studied rocks are basaltic trachyandesite, trachyandesite, trachyte, and trachydacite. Major elements reveal that the studied samples are metaluminous and their alumina saturation index varies from 0.71 to 1.02. The chondrite-normalized rare-earth element and mantle-normalized trace-element patterns show enrichment in light rare-earth elements (LREE) relative to heavy rare-earth elements (HREE) and in large ion lithophile elements (LILE) relative to high field strength elements (HFSE). As well they show a slightly negative Eu anomaly (Eu/Eu* = 0.72 – 0.97). The whole-rock geochemistry of the studied rocks suggests that they are related to each other by fractional crystallization. LA-MC-ICP-MS U-Pb analyses in zircon grains from two volcanic rock samples (GCH-119 and GCH-171) gave ages ranging of 5.47 ± 0.22 Ma to 2.44 ± 0.79 Ma, which corresponds to the Pliocene period. In four samples analysed
for Sr and Nd isotopes 87Sr/86Sr ratios range from 0.704082 to 0.705931 and εNd values vary
between +3.34 and +5. These values could be regarded to as representing mantle derived magmas.
Taking into account the comparing rare earth element (REE) patterns, an origin of the parental magmas in enriched lithospheric mantle is suggested. Finally, it is concluded that Pliocene Gandab volcanic rocks are related to the post-collision environment that followed the Neo-Tethys subduction
The Farsi Version of the Strength and Difficulties Questionnaire Self Report Form: The Normative Data and Scale Properties
Objective:This study was performed to evaluate the normative data and psychometric properties and the internal consistency of the Farsi (Persian) version of the Strength and Difficulties Questionnaire (SDQ) self-report form, as a screening tool in a community-based sample of 12 to 17 year-old adolescents of urban Tehran.Materials & Methods: In this investigation, 1105 adolescents (12 to 17 years old), selected from 250 clusters from all the 22 municipality areas of Tehran, responded to 25 questions of the Farsi version of SDQ self-report form. The frequency of each symptom domains according to Goodman's cutoff points and 90th percentile and the mean score in each subscale were determined.Results:The 90th percentile cutoff points were somewhat different from those of the previous reports. Using Goodman's cutoff points, the prevalence of symptom domains was relatively high. For example, 13.7 percent of the adolescents studied had total scores equal to 20 or more. There were significant correlations between different subscales and their constituting questions.Conclusion:Self-report form of SDQ is a valuable tool in the screening of adolescent psychopathologies. Frequency of majority of the symptom domains seems to be higher in the adolescents in Tehran urban areas
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Atomic Layer Deposition of for Passivating AlGaN/GaN High Electron Mobility Transistor Devices
Polycrystalline, partially epitaxial films were grown on AlGaN/GaN substrates by atomic layer deposition (ALD). With this ALD film as the insulator layer, the /AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors showed excellent electrical performance with a high I/I ratio of over 10 and a low subthreshold slope of 75 mV/dec. The UV/NHOH surface treatment on AlGaN/GaN prior to ALD was found to be critical for achieving these excellent figures. In addition, the dielectric is found to be negatively charged, which facilitates the enhancement-mode operation. While bare suffers from moisture degradation, depositing a moisture blocking layer of ALD can effectively eliminate this effect.Chemistry and Chemical Biolog
Mems based bridge monitoring supported by image-assisted total station
In this study, the feasibility of Micro-Electro-Mechanical System (MEMS) accelerometers and an image-assisted total station (IATS) for short-and long-term deformation monitoring of bridge structures is investigated. The MEMS sensors of type BNO055 from Bosch as part of a geo-sensor network are mounted at different positions of the bridge structure. In order to degrade the impact of systematic errors on the acceleration measurements, the deterministic calibration parameters are determined for fixed positions using a KUKA youBot in a climate chamber over certain temperature ranges. The measured acceleration data, with a sampling frequency of 100 Hz, yields accurate estimates of the modal parameters over short time intervals but suffer from accuracy degradation for absolute position estimates with time. To overcome this problem, video frames of a passive target, attached in the vicinity of one of the MEMS sensors, are captured from an embedded on-axis telescope camera of the IATS of type Leica Nova MS50 MultiStation with a practical sampling frequency of 10 Hz. To identify the modal parameters such as eigenfrequencies and modal damping for both acceleration and displacement time series, a damped harmonic oscillation model is employed together with an autoregressive (AR) model of coloured measurement noise. The AR model is solved by means of a generalized expectation maximization (GEM) algorithm. Subsequently, the estimated model parameters from the IATS are used for coordinate updates of the MEMS sensor within a Kalman filter approach. The experiment was performed for a synthetic bridge and the analysis shows an accuracy level of sub-millimetre for amplitudes and much better than 0.1 Hz for the frequencies. © 2019 M. Omidalizarandi et al
Geochemistry, petrology, and mineralization in volcanic rocks located in south Neyshabour, NE Iran
This paper presents the new geochemical isotopes Sr and Nd, and the mineralization data for the south Neyshabour volcanic rocks located in NE Iran. Based on the chemical classifications, the studied rocks are basaltic trachy andesite, trachy andesite, trachyte, and trachy dacite in composition. All the analyzed volcanic rocks display enrichment in light rare earth elements (LREE) relative to the heavy rare earth elements (HREE), have significant negative Ti and Nb anomalies, and have a positive U anomaly. The tectonic discrimination diagrams for the volcanic rocks in the studied area show a post-collisional arc environment. These characteristics are the specifications of the subduction-related volcanic rocks generated in a post-collisional setting. The initial 87Sr/86Sr ratios ranging from 0.70408 to 0.70593and the εNdi values between +3.34 and +5 for the four samples analyzed indicate that the studied rocks are derived from a lithospheric mantle source. Finally, it is concluded that these volcanic rocks should have formed in a post-collisional environment that followed the Neo-Tethys subduction. There are strong evidence for copper mineralization in these volcanic rocks. The main copper oxide minerals are malachite and atacamite. The copper sulfide minerals such as chalcocite, minor bornite, and covellit are also present. Chalcocite is the most abundant sulfide ore mineral present in this area. This mineralization is observed as open space filling and thin veinlets, and it is partially controlled by linear structures and fault zones. Based on the identified characteristics, this ore deposit is hydrothermal. Carbonate alteration is frequently seen in the area but argillic alteration is very low, and this issue displays a hydrothermal solution with an alkaline pH
Birds flee en mass from New Year’s Eve fireworks
Anthropogenic disturbances of wildlife, such as noise, human presence, hunting activity, and motor vehicles, are becoming an increasing concern in conservation biology. Fireworks are an important part of celebrations worldwide, and although humans often find fireworks spectacular, fireworks are probably perceived quite differently by wild animals. Behavioral responses to fireworks are difficult to study at night, and little is known about the negative effects fireworks may have on wildlife. Every year, thousands of tons of fireworks are lit by civilians on New Year’s Eve in the Netherlands. Using an operational weather radar, we quantified the reaction of birds to fireworks in 3 consecutive years. Thousands of birds took flight shortly after midnight, with high aerial movements lasting at least 45 min and peak densities measured at 500 m altitude. The highest densities were observed over grasslands and wetlands, including nature conservation sites, where thousands of waterfowl rest and feed. The Netherlands is the most important winter staging area for several species of waterfowl in Europe. We estimate that hundreds of thousands of birds in the Netherlands take flight due to fireworks. The spatial and temporal extent of disturbance is substantial, and potential consequences are discussed. Weather radar provides a unique opportunity to study the reaction of birds to fireworks, which has otherwise remained elusive
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