False-negative upper extremity ultrasound in the initial evaluation of patients with suspected subclavian vein thrombosis due to thoracic outlet syndrome (Paget-Schroetter syndrome)

OBJECTIVE: To assess the utilization and consequences of upper extremity Duplex ultrasound in the initial diagnostic evaluation of patients with suspected subclavian vein (SCV) thrombosis and venous thoracic outlet syndrome (VTOS). METHODS: A retrospective single-center review was conducted for patients that underwent primary surgical treatment for VTOS between 2008 and 2017, in whom an upper extremity ultrasound had been performed as the initial diagnostic test (n = 214). Clinical and treatment characteristics were compared between patients with positive and false-negative ultrasound studies. RESULTS: There were 122 men (57%) and 92 women (43%) that had presented with spontaneous idiopathic arm swelling, including 28 (13%) with proven pulmonary embolism, at a mean age of 30.7 ± 0.8 years (range 14-69). Upper extremity ultrasound had been performed 23.8 ± 12.2 days after the onset of symptoms, with confirmation of axillary-SCV thrombosis in 169 patients (79%) and negative results in 45 (21%). Of the false-negative ultrasound study reports, only 8 (18%) acknowledged limitations in visualizing the central SCV. Definitive diagnostic imaging (DDI) had been obtained by upper extremity venography in 175 (82%), computed tomography angiography in 24 (11%), and magnetic resonance angiography in 15 (7%), with 142 (66%) undergoing catheter-directed axillary-SCV thrombolysis. The mean interval between initial ultrasound and DDI was 48.9 ± 14.2 days with no significant difference between groups, but patients with a positive ultrasound were more likely to have DDI within 48 hours than those with a false-negative ultrasound (44% vs 24%; P = .02). At the time of surgical treatment, the SCV was widely patent following paraclavicular decompression and external venolysis alone in 74 patients (35%). Patch angioplasty was performed for focal SCV stenosis in 76 (36%) and bypass graft reconstruction for long-segment axillary-SCV occlusion in 63 (29%). Patients with false-negative initial ultrasound studies were significantly more likely to require SCV bypass reconstruction than those with a positive ultrasound (44% vs 25%; P = .02). CONCLUSIONS: Duplex ultrasound has significant limitations in the initial evaluation of patients with suspected SCV thrombosis, with false-negative results in 21% of patients with proven VTOS. This is rarely acknowledged in ultrasound reports, but false-negative ultrasound studies have the potential to delay definitive imaging, thrombolysis, and further treatment for VTOS. Initial false-negative ultrasound results are associated with progressive thrombus extension and a more frequent need for SCV bypass reconstruction at the time of surgical treatment

Mobile ad hoc network testbed using mobile robot technology

MANET (Mobile Ad Hoc Network) researchers have shown increased interest in using mobile robot technology for their testbed platforms. Thus, the main motivation of this paper is to review various robot-based MANET testbeds that have been developed in previously reported research. Additionally, suggestions to heighten mobility mechanisms by using mobile robots to be more practical, easy and inexpensive are also included in this paper, as we unveils ToMRobot, a low-cost MANET robot created from an ordinary remote control car that is capable of performing a real system MANET testbed with the addition of only a few low-cost electronic components. Despite greatly reduced costs, the ToMRobot does not sacrifice any of the necessary MANET basic structures and will still be easily customizable and upgradeable through the use of open hardware technology like Cubieboard2 and Arduino, as its robot controller. This paper will also include guidelines to enable technically limited MANET researchers to design and develop the ToMRobot. It is hoped that this paper achieves its two pronged objectives namely (i) to facilitate other MANET researchers by providing them with a source of reference that eases their decision making for selecting the best and most suitable MANET mobile robots for real mobility in their MANET testbeds (ii) to provide MANET researchers with a prospect of building their own MANET robots that can be applied in their own MANET testbed in the future

Experimental and Statistical Study of the Effect of Steel Fibers and Design Strength on the Variability in Repeated Impact Test Results

The ACI 544-2R repeated impact test is known as a low-cost and simple qualitative test to evaluate the impact strength of concrete. However, the test’s main deficiency is the high variability in its results. The effect of steel fibers and the compressive strength of concrete on the variability in repeated impact test results was investigated experimentally and statically in this study. Two batches from four mixtures were prepared and tested for this purpose. Hooked-end steel fibers were utilized in the fibrous mixtures. The mixtures NC, NC-SF0.5 and NC-SF1.0 were normal strength mixtures with 0, 0.5 and 1.0% of steel fibers, respectively, while HC was a plain high-strength mixture. The impact tests were conducted using an automatic testing machine following the setup of the ACI 544-2R repeated impact test. The impact numbers at cracking (N1) and at failure (N2) were recorded for both batches of the four mixtures. The results were also analyzed using the normal probability and Weibull distribution tests. The test results showed that the fibers increased the impact results at the cracking stage and significantly increased the failure impact resistance. Adding 0.5 and 1.0% of steel fibers increased the N1 by up to 66 and 111%, respectively, and increased the N2 by 114 and 374%, respectively. The test results also showed that duplicating the design compressive strength from 40 to 80 MPa increased the impact resistance by up to approximately 190%. The test results revealed no clear trend of an effect of steel fibers and compressive strength on the variability in the test results

Characteristics of palm oil clinker as replacement for oil palm shell in lightweight concrete subjected to elevated temperature

This article reports the effects of elevated temperature resistance capacity of palm oil clinker (POC) at elevated temperatures; POC was used to replace oil palm shell COPS) as coarse aggregate in oil palm shell concrete (OPSC). The replacement of OPS with POC was done to enhance the performance of concrete before and after exposure when subjected to evaluated temperature. A series of concrete mixes was prepared with 25%, 50%, 75% and 100% replacement of OPS with POC as coarse aggregate in OPSC and the specimens were subjected to elevated temperature of up to 500 degrees C for a period of 30 min and 60 min. Thermogravimetric analysis (TGA) was carried out to check the elevated temperature resistance capacity of OPS and POC. In addition, weight loss, residual compressive strength, colour change in the concrete, cracking on the surface of concrete specimens and ultrasonic pulse velocity (UPV) of OPSC were evaluated at elevated temperatures. TGA analysis shows OPS aggregate loses about 63% of its weight when exposed to temperatures between 285 degrees C and 478 degrees C; however, POC aggregate showed excellent elevated temperature resistance as there was insignificant weight loss of less than 1%. The results of OPSC specimens subjected to 500 degrees C for a period of 60 min showed the number of cracks decreases with the increase of POC content and subsequently the crack width also decreases from 0.319 mm to 0.122 mm. The residual compressive strength loss of specimens with 100% OPS was found as 76% when exposed to 500 degrees C for a period of 60 min and this loss reduces gradually with the increase in POC content; hence at 100% OPS replacement with POC, the loss of compressive strength of only 9% indicates vast improvement of OPSC using POC. Moreover, with the increase in the duration from 30 min to 60 min exposure at 500 degrees C, the loss of concrete compressive strength and UPV values was found higher. (C) 2015 Elsevier Ltd. All rights reserved

Performance evaluation of palm oil clinker as coarse aggregate in high strength lightweight concrete

The enhancement in the mechanical properties of high strength lightweight concrete (HSLWC) utilizing palm oil clinker (POC) as a replacement for oil palm shell (OPS) as lightweight coarse aggregate has been investigated and reported. A series of concrete mixes was prepared with 25%, 50%, 75% and 100% replacement of coarse aggregate by POC in HSLWC, while setting other parameters as constant. The parameters investigated include slump value, compressive strength, stress-strain behaviour, modulus of elasticity and its normalization, ultrasonic pulse velocity (UPV) and failure modes. The results showed that the replacement of OPS by POC as coarse aggregate has significant positive impact on compressive strength, modulus of elasticity and UPV. The highest compressive strength of about 63 MPa obtained for the mix with POC was about 43% higher than the control mix. Moreover, the enhancement in modulus of elasticity up to 2.5 times could significantly control the deflection

Repeated Impact Response of Normal- and High-Strength Concrete Subjected to Temperatures up to 600 °C

With the aim of investigating the response of concrete to the dual effect of accidental fire high temperatures and possible induced impacts due to falling fragmented or burst parts or objects, an experimental work is conducted in this study to explore the influence of exposure to temperatures of 200, 400 and 600 °C on the responses of concrete specimens subjected to impact loads. Cylindrical specimens are tested using the recommended repeated impact procedure of the ACI 544-2R test. Three concrete mixtures with concrete nominal design strengths of 20, 40 and 80 MPa are introduced to represent different levels of concrete strength. From each concrete mixture, 24 cylinders and 12 cubes are prepared to evaluate the residual impact resistance and compressive strength. Six cylindrical specimens and three cubes from each concrete mixture are heated to each of the three levels of high temperatures, while the other six cylinders and three cubes are tested without heating as reference specimens. The test results show that the behavior of impact resistance is completely different from that of compressive strength after exposure to high temperatures; the cylindrical specimens lose more than 80% of the cracking and failure impact resistance after exposure to 200 °C, while impact resistance almost vanishes after exposure to 400 and 600 °C. Concrete compressive strength is found to be effective on the unheated impact specimens, where the higher-strength cylinders retain significantly higher impact numbers. This effect noticeably decreases after exposure to 200 and 400 °C, and vanishes after exposure to 600 °C

Recurrent intermammary pilonidal sinus: a rare case with literature review.

Introduction: the usual area for pilonidal sinus disease is the sacrococcygeal region. The aim of this study is to report an extremely rare condition of recurrent intermammary pilonidal disease with a brief literature review.  Case report:   A 22 -year-old married lady complained of discharge, pain, and redness in the intermammary region for 1 year.  On examination, there is a single discharging sinus and an old scar around it. Excisional biopsy confirmed the diagnosis of pilonidal sinus. Conclusion:  However its rare, intermammary pilonidal sinus may recur and require surgical re-intervention