Dead Reckoning Localization Technique for Mobile Wireless Sensor Networks

Localization in wireless sensor networks not only provides a node with its geographical location but also a basic requirement for other applications such as geographical routing. Although a rich literature is available for localization in static WSN, not enough work is done for mobile WSNs, owing to the complexity due to node mobility. Most of the existing techniques for localization in mobile WSNs uses Monte-Carlo localization, which is not only time-consuming but also memory intensive. They, consider either the unknown nodes or anchor nodes to be static. In this paper, we propose a technique called Dead Reckoning Localization for mobile WSNs. In the proposed technique all nodes (unknown nodes as well as anchor nodes) are mobile. Localization in DRLMSN is done at discrete time intervals called checkpoints. Unknown nodes are localized for the first time using three anchor nodes. For their subsequent localizations, only two anchor nodes are used. The proposed technique estimates two possible locations of a node Using Bezouts theorem. A dead reckoning approach is used to select one of the two estimated locations. We have evaluated DRLMSN through simulation using Castalia simulator, and is compared with a similar technique called RSS-MCL proposed by Wang and Zhu .Comment: Journal Paper, IET Wireless Sensor Systems, 201

Single stage oncologic resection and reconstruction: A step toward development of sarcoma service in resource constrained country

Tumor free-margin surgical resection remains the single most important treatment in the curative therapy of musculoskeletal tumor of limbs. Refinements in surgical techniques have led to increased function preservation and limb salvage. Patients and Methods: The records of patients (n = 24) who underwent microsurgical soft tissue reconstruction subsequent to resection of limb tumour during the period 2006 to 2011 were reviewed. Primary outcome i.e. uptake of the flap was evaluated. Perioperative morbidities were also noted including donor as well as recipient site complications. Assessment of Functional outcome (Musculoskeletal Tumor Society score, MSTS) local recurrence, free survival, and disease-specific survival was also made. Results: Twenty four patients (age range: 7 - 72 years) who have undergone tumor resection followed by flap coverage were identified. Lower limb reconstruction outnumbered upper limb by 6:1. Complications included, one complete failure of free vascularized iliac crest flap done for reconstruction of a heel defect. One of the patients had secondary hemorrhage 10 days after surgery. Another patient with internal hemipelvectomy for Ewing’s sarcoma had a dura puncture during resection of sacrum. Partial epidermal necrosis was evident in four cases. Eighty three percent of the patients remained alive (n = 20), 19 of whom currently have no evidence of disease (NED) Disease recurrence was noted in three patients. Overall MSTS score was 73.5%. Conclusion: The microsurgical repair of defects is a reliable option that, though not free of complications, is necessary in selected cases. The procedure enables both adequate oncosurgical resection and function preservation

Complex biological reconstruction after wide excision of osteogenic sarcoma in lower extremities

Wide margin resection of extremity tumor sometimes leaves a huge soft tissue and bony defects in limb salvage surgery. Adequate management of these defects is an absolute requirement when aiming for functional limb. Multidisciplinary management in such cases is an answer when complex biologic reconstruction is desired. We aim to present cases of osteogenic sarcoma of lower extremity requiring combined surgical approach to achieve effective musculoskeletal reconstruction. Patients and Methods. From 2006 to 2010 ten patients were operated on for osteogenic sarcoma of lower extremity requiring complex musculoskeletal reconstruction. Results. Six patients had pathology around knee joint, whereas one each with mid tibia, mid femur, proximal femur, and heel bone. Locking compression plate was used in 7 patients including six with periarticular disease. Eight out of ten patients underwent biologic reconstruction using autograft; endoprosthetic reconstruction and hindquarter amputation were done in the remaining two patients. Vascularized fibula was done in five patients, sural artery flap which was primarily done in three patients, spare part fillet flap, free iliac crest flap, and Gastrocnemius flap was done in one patient each. Secondary hemorrhage, infection, nonunion, wound dehiscence, and flap failure were notable complications in four patients. The Average Musculoskeletal Tumor Society score was 89%. Conclusion. Combined surgical approach results in cosmetically acceptable and functional limb

Predictors of length of hospital stay after total hip replacement

Purpose: To identify variables affecting length of hospital stay after total hip replacement (THR) while controlling for potential confounders. Methods: Records of 199 consecutive elective unilateral THRs were reviewed. Clinical and demographic data including age, gender, body mass index, comorbidities, surgical factors (surgical approach, type of prosthesis, use of cement, operating time), anaesthetic factors (type of anaesthesia, ASA physical status), and length of hospital stay were recorded. Results: 64% of Patients left hospital within 12 days, 28% within 3 weeks, and 8% after 3 weeks. The median length of hospital stay was longer in women than men (11.5 vs. 9 days, p=0.009), in Patients aged \u3e65 years than those younger (13 vs. 9 days, p65 years than those younger (61% vs. 37% or 24%, p65 years (pConclusions: Prolonged hospital stay after THR is largely predetermined by case mix. Our study helps to identify individuals who need longer rehabilitation and more care

Butt fusion welding of polyethylene pipes

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The butt fusion process is extensively used in the joining of polyethylene (PE) pipes by the water and gas industries. This welding process although deceptively simple, is rather poorly understood, with much of the initial developments being of a rather empirical nature. The Water Research centre (WRc) have funded the present research in an attempt to optimise the welding of high pressure pipeline (PE100) systems. The main aims of this research were to investigate the effect of different welding conditions on the physical and mechanical properties of the joints produced and to investigate these effects on the micro- and macro-structures of the joints produced. A series of welds were made using Eltex Tub 124 and Rigidex 002-50 pipes of 180mm diameter. The fusion pressure and heatsoak times were varied. A milling machine witha twin cutter arrangement was used to obtain the test specimens from around the circumference of the pipes. Differential scanning calorimetry was used to study the effect of sample preparation methodology on the thermo-oxidative stability. Polarised light microscopy and image analysis were used to study the macro- and micro-structural developments in the weld joint. Joint strength was evaluated via standard and non-standard tensile test methods. Milling the samples to produce the test specimens was found to decrease significantly the thermo-oxidative resistance of the polymer. Reasons for this behaviour have been proposed. In order to achieve high quality thin films from microtomy, custom-made blades were used. This programme also developed the optimum polishing method for the microtomed blades. The macro-structure of the bead: its shape and dimensions were found to be a function of temperature and pressure. Correlation was found between the bead geometry and the position around the circumference of the pipe. The macrostructures within the weld zone also showed this dependence on the position along the circumference of the pipe. An examination of the microstructures of each weld had shown the presence of five different zones. The feasibility of using microtomed thin sections in a tensile test was demonstrated. The test method provides a means to study failure initiation and propagation in the tensile test specimen. Initial deformation was found to occur in the centre of the melt-affected zone (MAZ) and the final failure occurs at the junction of the weld bead and the bulk polymer. Tests on films without the weld bead showed that maximum deformation occurred at the centre of the sample within the MAZ. The presence of the bead and the asymmetry in the test specimens caused by the welding process were found to have a significant influence on the failure mode and the failure strain. The strain rate was also found to play a significant role in both beaded and debeaded samples. The failure was initiated from the pseudo notches in the beaded samples. In the debeaded sample the failure was within the MAZ

Complications of total hip replacement

Objective: To determine the factors causing complications in unilateral total hip replacement. Study Design: Analytical study. Place and Duration of Study: The Aga Khan University Hospital, Karachi, between 2000 and 2010. Methodology: During the study period, 199 patients underwent elective unilateral total hip replacement at the Aga Khan University Hospital. Patients were divided into two groups on the basis of postoperative complications within 30 days of surgery. Significant factors at 5% significance level on univariate analysis were further analyzed by multivariate logistic regression. Results: Postoperative complications occurred in 39 patients (19.6%); dislocation being most common in 13 patients (6.5%), followed by wound infection in four (2%), all of these patients required intervention. Other minor complications which were managed conservatively included wound infection (2.5%), urinary tract infection (2.5%), dislocation (1%), pleural effusion and pneumonia (2%), deep venous thrombosis (0.5%) and myocardial infarction (0.5%). On univariate analysis, patients with ASA III and IV, peri-operative blood transfusion, pre-operative hip deformity and post-operative bisphosphonate use were significantly associated with complications. On multi-variate analysis, adjusted odd\u27s ratio for perioperative transfusion (3; 95% CI: 1.17-7.7) and hip deformity (3.2, 95% CI: 1.4-3.4) was found statistically significant. Conclusion: Pre-operative hip deformity and perioperative blood transfusion significantly influence the rates of complication after unilateral THR

K Wire fixation of supra-condylar humerus fractures in children. Is ulnar nerve at risk?

Abstract OBJECTIVE: To compare iatrogenic ulnar nerve injury in lateral entry pin fixation versus medial and lateral entry pin fixation in the treatment of supracondylar fractures of the humerus in children. Measurement of clinical parameters in terms of elbow range of motion and postop radiographic alignment was also targeted. METHODS: The retrospective cohort study was conducted at Aga Khan University Hospital, Karachi, and comprised data of paediatric patients who underwent closed reduction and percutaneous pin fixation for the treatment of displaced extension type supracondylar fractures of the humerus between July 2007 and June 2012. Data regarding socio-demographic status, disease and procedure variables was collected from patient files and was analysed using SPSS 19. RESULTS: There were 71patients; 37(52%) in the lateral entry group and 34(48%) in the medial and lateral entry group. The two groups were similar in terms of mean age, gender distribution, and preoperative displacement, comminution, and associated vascular and nerve status (p\u3e 0.05 each). There were no cases of iatrogenic ulnar nerve injury in either group and no significant differences between groups with respect to the elbow range of motion and radiological parameters (p\u3e 0.05 each). CONCLUSIONS: With the use of the specific techniques employed, both lateral entry pin fixation and medial and lateral entry pin fixation were effective in the treatment of displaced extension type supracondylar humerus fractures in children

Outcomes of internal hemipelvectomy for pelvic tumors: a developing country’s prospective

Introduction: Previously, external hemipelvectomy was the mainstay of treatment for pelvic tumors. However, with technological advancements, limb salvage procedures such as internal hemipelvectomy have emerged as a viable alternative. However, there is limited literature available on long-term outcomes and complications of internal hemipelvectomy, especially from developing countries. Therefore, the objective of this study was to share our experience of internal hemipelvectomy at a tertiary care center in a developing country. Materials and methods: A retrospective review was conducted in which all 24 patients undergoing internal hemipelvectomy from January 1, 2005 to December 31, 2015 at our institution were included. Medical record files were reviewed for intraoperative and early and late postoperative complications, and functional outcomes were assessed by contacting each patient on telephone. Results: Ewing sarcoma was found to be the most common diagnosis, followed by osteosarcoma as the second most common. The mean follow-up period was 18.7 ± 13.9 months. Intraoperatively there were 4 cases of iatrogenic neurovascular injury and 2 cases each of urinary tract injury and dural tear. Four patients developed early wound infections, 7 developed late wound infections, and 2 developed flap necrosis. Three patients developed recurrence, whereas 7 patients developed metastasis postoperatively. The mean survival was calculated to be 28 months and the mean Musculoskeletal Tumor Society score was 19.3 ± 5.2. Conclusions: Outcomes and prevalence of complications shown in this study are comparable to those in the international literature, which suggests that hemipelvectomy is a viable option in developing countries also. However, more such studies are warranted to validate the findings and to identify the challenges and morbidities associated with hemipelvectomy in Asian and developing countries