Movement detection using a reciprocal received signal strength model

Received signal strength measurements of commodity radios can be utilized for sensing the surrounding environment. This work harnesses the signal strength measurements for estimating time periods when a person is stationary and moving. A novel reciprocal signal strength model is presented, and an energy detector is developed. It is shown that the decision threshold can be calculated in closed form for the proposed model. In addition, the observation time window can be minimized to one communication cycle which equals 58 milliseconds in our case. Using real-world experimental data from two different environments, it is demonstrated that movement can be correctly detected over 99% of the time.acceptedVersionPeer reviewe

Adhesion-preventing properties of 4% icodextrin and canola oil: a comparative experimental study

OBJECTIVE: Postsurgical abdominal adhesions are common, serious postoperative complications. The present study compared the usefulness of 4% icodextrin and canola oil in preventing postoperative peritoneal adhesions. METHODS: Twenty-four Wistar albino rats were divided into three groups. Following a laparotomy, a serosal abrasion was made by brushing the cecum, and 3 mL of 0.9% NaCl, 4% icodextrin, or 3 mL of canola oil were intraperitoneally administered for the control, icodextrin, and canola oil groups, respectively. The abdomen was then closed. All of the rats were sacrificed at day 10. Macroscopic, histopathological, and biochemical evaluations were performed. The results were statistically analyzed using Kruskal-Wallis and ANOVA tests. RESULTS: Macroscopic analyses revealed that both canola oil and 4% icodextrin reduced adhesion formation, but the difference was not statistically significant (p = 0.17). The histopathological examinations revealed no significant differences in terms of giant cell, lymphocyte/plasmocyte, neutrophil, ICAM1, or PECAM1 scores. However, both canola oil and 4% icodextrin significantly reduced fibrosis (p = 0.025). In the canola oil group, the histiocytic reactions were significantly increased (p = 0.001), and the hydroxyproline levels were significantly lower than those in the other groups (p = 0.034). CONCLUSIONS: In the present study, canola oil was determined to be superior to 4% icodextrin in lowering hydroxyproline levels and increasing histiocytic reactions. Considering these results, we believe that canola oil is a promising agent for preventing adhesion formation

Random Finite Set Approach to Signal Strength Based Passive Localization and Tracking

Radio frequency sensor networks can be utilized for locating and tracking people within coverage area of the network. The technology is based on the fact that humans alter properties of the wireless propagation channel which is observed in the channel estimates, enabling tracking without requiring people to carry any sensor, tag or device. Considerable efforts have been made to model the human induced perturbations to the channel and develop flexible models that adapt to the unique propagation environment to which the network is deployed in. This paper proposes a noteworthy conceptual shift in the design of passive localization and tracking systems as the focus is shifted from channel modeling to filter design. We approach the problem using random finite set theory enabling us to model detections, missed detections, false alarms and unknown data association in a rigorous manner. The Bayesian filtering recursion applied with random finite sets is presented and a computationally tractable Gaussian sum filter is developed. The development efforts of the paper are validated using experimental data and the results imply that the proposed approach can decrease the tracking error up to 48% with respect to a benchmark solution.Peer reviewe

Direct Path Interference Suppression Requirements for Bistatic Backscatter Communication System

The ambient backscatter communication (AmBC) system utilizes the existing ambient RF signals present in the atmosphere for backscattering the signal. One of the challenges for AmBC system is the interference at the receiver module caused by the direct path signal from the ambient source. The purpose of this paper is to study the coverage aspects of the bi-static backscatter communication system in a typical urban environment at sub-1GHz frequencies using simulations in MATLAB. For the simulation, 3rd generation partnership project (3GPP) urban microcellular and international telecommunication union (ITU) device-to-device (D2D) propagation models are used. Moreover, the dynamic range i.e., the difference in the received power level of the direct path and the backscatter path is investigated. For correctly decoding the backscatter signal at the reader, the target value set for the dynamic range is less than 30 dB. This paper studies the importance of direct path interference suppression for the successful deployment of a bi-static backscatter communication system.acceptedVersionPeer reviewe

A migrated sewing needle to the liver.

A 52-year-old woman was investigated for right upper quadrant abdominal pain. Abdominal X-ray revealed a linear metallic object superposed to the liver (Fig. A, arrow). Patient’s history was irrelevant except for a breast biopsy 20 years previously. She did not report any blunt abdominal trauma. Unenhanced abdominal CT was performed for exact localization of the foreign body. A linear metallic opacity was observed in the medial segment of left liver lobe (Fig. B). At laparotomy, a needle was found in the parenchyma over the hilar plate of the liver. Its location was checked by intraoperative fluoroscopy then it was extracted with a clamp through a small incision in the liver parenchyma. High resolution X-ray graph revealed that the foreign body was a sewing needle (Fig. C). At eight months follow up, she is symptom free without any complication

Localization Services for Online Common Operational Picture and Situation Awareness

Many operations, be they military, police, rescue, or other field operations, require localization services and online situation awareness to make them effective. Questions such as how many people are inside a building and their locations are essential. In this paper, an online localization and situation awareness system is presented, called Mobile Urban Situation Awareness System (MUSAS), for gathering and maintaining localization information, to form a common operational picture. The MUSAS provides multiple localization services, as well as visualization of other sensor data, in a common frame of reference. The information and common operational picture of the system is conveyed to all parties involved in the operation, the field team, and people in the command post. In this paper, a general system architecture for enabling localization based situation awareness is designed and the MUSAS system solution is presented. The developed subsystem components and forming of the common operational picture are summarized, and the future potential of the system for various scenarios is discussed. In the demonstration, the MUSAS is deployed to an unknown building, in an ad hoc fashion, to provide situation awareness in an urban indoor military operation.Peer reviewe

Quality Improvement for Portal Vein Embolization

Fibrin sealant is used in many areas of surgery. We present a novel aspect of flap insetting in the ischial region using fibrin spray to seal the transferred tissue. We analyzed 10 patients suffering from decubital ulcers and assessed drainage output, time of drain removal, as well as complications following fasciocutaneous flap surgery. Patients were randomized to receive sprayed fibrin glue (study group) or not (control group) before wound closure. The mean drainage time was 4 +/- 1 days in the study group and 6 +/- 1 days in the control group ( P = 0.06). The mean drainage volume was 100 +/- 20 mL in the study group and 168 +/- 30 mL in the control group ( P < 0.01). Fibrin sealant led to reduced drainage volumes and duration of drainage, indicating a beneficial effect of the application of fibrin glue in fasciocutaneous flap surgery for pressure sore coverage

Association between biliary complications and technique of hilar division (extrahepatic vs. intrahepatic) in major liver resections

BACKGROUND: Division of major vascular and biliary structures during major hepatectomies can be carried out either extrahepatically at the porta hepatic or intrahepatically during the parenchymal transection. In this retrospective study we test the hypothesis that the intrahepatic technique is associated with less early biliary complications. METHODS: 150 patients who underwent major hepatectomies were retrospectively allocated into an intrahepatic group (n = 100) and an extrahepatic group (n = 50) based on the technique of hilar division. The two groups were operated by two different surgical teams, each one favoring one of the two approaches for hilar dissection. Operative data (warm ischemic time, operative time, blood loss), biliary complications, morbidity and mortality rates were analyzed. RESULTS: In extrahepatic patients, operative time was longer (245 ± 50 vs 214 ± 38 min, p < 0.05) while the overall complication rate (55% vs 52%), hospital stay (13 ± 7 vs 12 ± 4 days), bile leak rate (22% vs 20%) and mortality (2% vs 2%) were similar compared to intrahepatic patients. However, most (57%) bile leaks in extrahepatic patients were grade II (leaks that required non-operative interventional treatment, while most (70%) leaks in the intrahepatic group were grade I (leaks that resolved and presented two injuries (4%) of the remaining bile ducts (p < 0.05). CONCLUSION: Intrahepatic hilar division is as safe as extrahepatic hilar division in terms of intraoperative blood requirements, morbidity and mortality. The extrahepatic technique is associated with more severe bile leaks and biliary injuries

Liver Volumetry Plug and Play: Do It Yourself with ImageJ

AB - BACKGROUND: A small remnant liver volume is an important risk factor for posthepatectomy liver failure and can be predicted accurately by computed tomography (CT) volumetry using radiologic image analysis software. Unfortunately, this software is expensive and usually requires support by a radiologist. ImageJ is a freely downloadable image analysis software package developed by the National Institute of Health (NIH) and brings liver volumetry to the surgeon's desktop. We aimed to assess the accuracy of ImageJ for hepatic CT volumetry. METHODS: ImageJ was downloaded from http://www.rsb.info.nih.gov/ij/ . Preoperative CT scans of 15 patients who underwent liver resection for colorectal cancer liver metastases were retrospectively analyzed. Scans were opened in ImageJ; and the liver, all metastases, and the intended parenchymal transection line were manually outlined on each slice. The area of each selected region, metastasis, resection specimen, and remnant liver was multiplied by the slice thickness to calculate volume. Volumes of virtual liver resection specimens measured with ImageJ were compared with specimen weights and calculated volumes obtained during pathology examination after resection. RESULTS: There was an excellent correlation between the volumes calculated with ImageJ and the actual measured weights of the resection specimens (r(2) = 0.98, p < 0.0001). The weight/volume ratio amounted to 0.88 +/- 0.04 (standard error) and was in agreement with our earlier findings using CT-linked radiologic software. CONCLUSION: ImageJ can be used for accurate hepatic CT volumetry on a personal computer. This application brings CT volumetry to the surgeon's desktop at no expense and is particularly useful in cases of tertiary referred patients, who already have a proper CT scan on CD-ROM from the referring institution. Most likely the discrepancy between volume and weight results from exsanguination of the liver after resectio