Comparison of Direct Intersection and Sonogram Methods for Acoustic Indoor Localization of Persons.

We discuss two methods to detect the presence and location of a person in an acoustically small-scale room and compare the performances for a simulated person in distances between 1 and 2 m. The first method is Direct Intersection, which determines a coordinate point based on the intersection of spheroids defined by observed distances of high-intensity reverberations. The second method, Sonogram analysis, overlays all channels' room impulse responses to generate an intensity map for the observed environment. We demonstrate that the former method has lower computational complexity that almost halves the execution time in the best observed case, but about 7 times slower in the worst case compared to the Sonogram method while using 2.4 times less memory. Both approaches yield similar mean absolute localization errors between 0.3 and 0.9 m. The Direct Intersection method performs more precise in the best case, while the Sonogram method performs more robustly.

Asynchronous Chirp Slope Keying for Underwater Acoustic Communication.

We propose an asynchronous acoustic chirp slope keying to map short bit sequences on single or multiple bands without preamble or error correction coding on the physical layer. We introduce a symbol detection scheme in the demodulator that uses the superposed matched filter results of up and down chirp references to estimate the symbol timing, which removes the requirement of a preamble for symbol synchronization. Details of the implementation are disclosed and discussed, and the performance is verified in a pool measurement on laboratory scale, as well as the simulation for a channel containing Rayleigh fading and Additive White Gaussian Noise. For time-bandwidth products (TB) of 50 in single band mode, a raw data rate of 100 bit/s is simulated to achieve bit error rates (BER) below 0.001 for signal-to-noise ratios above -6 dB. In dual-band mode, for TB of 25 and a data rate of 200 bit/s, the same bit error level was achieved for signal-to-noise ratios above 0 dB. The simulated packet error rates (PER) follow the general behavior of the BER, but with a higher error probability, which increases with the length of bits in each packet.

Simulation-Based Resilience Quantification of an Indoor Ultrasound Localization System in the Presence of Disruptions.

Time difference of arrival (TDOA) based indoor ultrasound localization systems are prone to multiple disruptions and demand reliable, and resilient position accuracy during operation. In this challenging context, a missing link to evaluate the performance of such systems is a simulation approach to test their robustness in the presence of disruptions. This approach cannot only replace experiments in early phases of development but could also be used to study susceptibility, robustness, response, and recovery in case of disruptions. The paper presents a simulation framework for a TDOA-based indoor ultrasound localization system and ways to introduce different types of disruptions. This framework can be used to test the performance of TDOA-based localization algorithms in the presence of disruptions. Resilience quantification results are presented for representative disruptions. Based on these quantities, it is found that localization with arc-tangent cost function is approximately 30% more resilient than the linear cost function. The simulation approach is shown to apply to resilience engineering and can be used to increase the efficiency and quality of indoor localization methods.

Acoustic Indoor Localization Augmentation by Self-Calibration and Machine Learning.

An acoustic transmitter can be located by having multiple static microphones. These microphones are synchronized and measure the time differences of arrival (TDoA). Usually, the positions of the microphones are assumed to be known in advance. However, in practice, this means they have to be manually measured, which is a cumbersome job and is prone to errors. In this paper, we present two novel approaches which do not require manual measurement of the receiver positions. The first method uses an inertial measurement unit (IMU), in addition to the acoustic transmitter, to estimate the positions of the receivers. By using an IMU as an additional source of information, the non-convex optimizers are less likely to fall into local minima. Consequently, the success rate is increased and measurements with large errors have less influence on the final estimation. The second method we present in this paper consists of using machine learning to learn the TDoA signatures of certain regions of the localization area. By doing this, the target can be located without knowing where the microphones are and whether the received signals are in line-of-sight or not. We use an artificial neural network and random forest classification for this purpose.

Rare-Earth-Doped Nanoparticles for Short-Wave Infrared Fluorescence Bioimaging and Molecular Targeting of αVß3-Expressing Tumors.

The use of short-wave infrared (SWIR) light for fluorescence bioimaging offers the advantage of reduced photon scattering and improved tissue penetration compared to traditional shorter wavelength imaging approaches. While several nanomaterials have been shown capable of generating SWIR emissions, rare-earth-doped nanoparticles (REs) have emerged as an exceptionally bright and biocompatible class of SWIR emitters. Here, we demonstrate SWIR imaging of REs for several applications, including lymphatic mapping, real-time monitoring of probe biodistribution, and molecular targeting of the αvß3 integrin in a tumor model. We further quantified the resolution and depth penetration limits of SWIR light emitted by REs in a customized imaging unit engineered for SWIR imaging of live small animals. Our results indicate that SWIR light has broad utility for preclinical biomedical imaging and demonstrates the potential for molecular imaging using targeted REs.

X-ray-induced shortwave infrared biomedical imaging using rare-earth nanoprobes.

Shortwave infrared (SWIR or NIR-II) light provides significant advantages for imaging biological structures due to reduced autofluorescence and photon scattering. Here, we report on the development of rare-earth nanoprobes that exhibit SWIR luminescence following X-ray irradiation. We demonstrate the ability of X-ray-induced SWIR luminescence (X-IR) to monitor biodistribution and map lymphatic drainage. Our results indicate X-IR imaging is a promising new modality for preclinical applications and has potential for dual-modality molecular disease imaging.

Valve cuspidity: a risk factor for aortic valve repair?

BACKGROUND: The aim of this study was to analyze short- and mid-term results after aortic valve (AV) repair with particular regard to the impact of valve cuspidity (bicuspid versus tricuspid aortic valve). METHODS: One hundred patients with aortic regurgitation (AR) undergoing aortic valve repair between November 2007 and October 2012 were included in the study. Sixty patients had bicuspid AV (BAV group; 11 females) and 40 patients had tricuspid AV (TAV group; 13 females). AR > grade 2 was present in 47 (78%) patients in the BAV and in 35 (88%) patients in the TAV group. Follow-up was complete in 100% and median was 25 months. RESULTS: Isolated aortic valve repair was performed in 27 (45%) of BAV patients and in six (15%) of TAV patients. Replacement of the ascending aorta and/or aortic root was performed in 33 (55%) of BAV patients and in 34 (86%) of TAV patients. There was no death within 30 days postoperatively, while two patients died (TAV group) during the follow-up period. There was no statistical difference between BAV and TAV groups with regard to the survival (100 ± 0% vs. 95 ± 4%, p = 0.102), the three-year freedom from AV-related reoperation (90 ± 5% vs. 89 ± 6%, p = 0.456), and the three-year freedom from AR grade > 2 (86 ± 6% vs. 82 ± 7%, p = 0.866), respectively. CONCLUSIONS: This study demonstrates no difference in mid-term results after regurgitant bicuspid and tricuspid aortic valve repair, suggesting that bicuspid valve may not be a risk factor for aortic valve repair.

Long-term survival after radical surgery for renal cell carcinoma with tumour thrombus extension into the right atrium.

UNLABELLED: What's known on the subject? and What does the study add? Surgical treatment of renal cell carcinoma (RCC) with tumour thrombus extending into the right atrium remains, despite its complexity and specific technical aspects, the only radical therapeutic option. This single-centre study, unique in size for this rare condition, reports early and late results over a period of 18 years. All patients were operated on using a standardised protocol with use of cardiopulmonary bypass and deep hypothermic circulatory arrest. Overall and cancer-specific cumulative survival was better than in other reports. OBJECTIVE: To evaluate the long-term results of radical surgical management of renal cell carcinoma (RCC) with tumour thrombus extension (TTE) level IV into the right atrium (RCC/TTE IV) in a large single-institution series. PATIENTS AND METHODS: Radical complex urological and cardio-surgical procedure was performed over a period of 18 years (1993-2010) on 21 patients with RCC/TTE IV. A radical nephrectomy was performed followed by sternotomy, institution of cardiopulmonary bypass and extraction of the intracardiac tumour thrombus under direct visual control during deep hypothermic circulatory arrest (DHCA). Perioperative and postoperative variables, and long-term overall and cancer-specific survival using the Kaplan-Meier method were analysed. RESULTS: In all patients, precise removal of tumour thrombus was accomplished in a bloodless field during DHCA. The mean (sd) duration of circulatory arrest was 16 (6) min at a mean hypothermia of 20 (3) °C. In-hospital mortality was 9.5% (two patients). The median survival (including in-hospital mortality) was 25 months. In Kaplan-Meier analysis, 2- and 5-year overall cumulative survival rate was 57 (95% confidence interval, CI 36-78)% and 37 (95% CI 15-58)%, respectively. Cancer-specific cumulative survival was 68 (95% CI 49-89)% at 2 years and 51 (95% CI 28-74)% at 5 years. CONCLUSIONS: Late outcome after radical surgical treatment in patients with RCC and TTE reaching up to the right atrium justifies this extensive procedure. Cardiopulmonary bypass with DHCA allows safe and precise extirpation of all intracaval and intracardiac tumour mass.

"Elephant trunk" and endovascular stentgrafting--a hybrid approach to the treatment of extensive thoracic aortic aneurysm.

A hybrid approach to elephant trunk technique for treatment of thoracic aortic aneurysms combines a conventional surgical and endovascular therapy. Compared to surgery alone, there is a presumption that mortality and morbidity is reduced. We present a case report of a 42-year-old man with a giant aneurysm of the entire thoracic aorta, significant aortic and tricuspid regurgitation and ventricular septum defect. The patient underwent multiple consecutive operations and interventions having, among others, finally replaced the entire thoracic aorta with the use of the hybrid elephant trunk technique.

Renal cell carcinoma with intracardiac tumor thrombus extension: Radical surgery yields 2 years of postoperative survival in a single-center study over a period of 30 years.

Background: Renal cell carcinoma (RCC) with tumor thrombus extension into the right atrium (level IV) is a rare life-threatening clinical condition that can only be managed by means of a combined urological and cardiac surgical approach. The early and late outcomes of this radical treatment were analyzed in a large single-institution series over a period of 30 years. Methods: In 37 patients with RCC and intracardiac tumor thrombus extension, nephrectomy was performed followed by the extraction of the intracaval and intracardiac tumor thrombus under direct visual control during deep hypothermic circulatory arrest (DHCA). Recently, in 13 patients, selective aortic arch perfusion (SAAP) was instituted during DHCA. Results: In all patients, precise removal of the tumor thrombus was accomplished in a bloodless field. The mean duration of isolated DHCA was 15 ± 6 min, and 31.5 ± 10.2 min in the case of DHCA + SAAP, at a mean hypothermia of 22.7 ± 4°C. In-hospital mortality was 7.9% (3 patients). In Kaplan-Meier analysis, the estimated median survival was 26.4 months whereas the 5-year cancer-related survival rate was 51%. Conclusions: Despite its complexity, this extensive procedure can be performed safely with a generally uneventful postoperative course. The use of cardiopulmonary bypass with DHCA, with the advantage of SAAP, allows for a safe, precise, and complete extirpation of intracaval and intracardiac tumor mass. Late outcomes after radical surgical treatment in patients with RCC and tumor thrombus reaching up in the right atrium in our series justify this extensive procedure.

Repair of thoracic aortic aneurysm due to noninfectious aortitis.

BACKGROUND AND AIM: Isolated thoracic aortitis (ITA) is a newly-defined pathological entity with a still-unknown etiopathology and with some potential relationship to IgG4-related systemic disease. We investigated patients on whom the ascending aorta was operated to identify the clinical and histopathological features of ITA and its relationship to IgG4-related systemic disease. METHODS: Two hundred fifty-one patients underwent replacement of the ascending aorta. Retrospective review of all histological reports was done to identify noninfectious aortitis. Immunohistochemical analysis of resected specimens was performed in all cases. RESULTS: We found 11 (4.4%) patients with noninfectious aortitis aged 52 to 79 years; nine of the patients were female. All patients underwent ascending aorta replacement. The 30-day mortality was 0. During the follow-up period (median 12 months) four patients died (two of them because of progression of aortic disease). None of the seven living patients developed any IgG4-related diseases, and all had normal serum levels of IgG and IgG4. CONCLUSIONS: Surgical treatment of ITA has acceptable short- and mid-term results. Because follow-up serum levels of IgG and IgG4 were normal in survivors, postoperative corticosteroid therapy may not be indicated in patients in the absence of active vasculitis.

Modified hockey-stick approach to the mitral valve.

Modified biatrial approach to the mitral valve is described. The hockey-stick incision combines the advantage of excellent exposure with low surgical risk and easy reconstruction.

Peripheral tissue metabolism during off-pump versus on-pump coronary artery bypass graft surgery: the microdialysis study.

OBJECTIVE: The aim of this study was to monitor and compare metabolic changes in the skeletal muscle during coronary artery bypass grafting surgery with and without cardiopulmonary bypass (CPB) by means of interstitial microdialysis. Glucose, lactate, pyruvate and glycerol were assessed as markers of basic metabolism and tissue perfusion. METHODS: Twenty patients undergoing surgical myocardial revascularization were enrolled in this pilot study. Ten patients were operated on without CPB (group A, off-pump) and 10 patients using normothermic CPB (group B, on-pump). Interstitial microdialysis was performed by a CMA 60 (CMA/Microdialysis AB, Sweden) probe, inserted into the patient's left deltoid muscle. Microdialysis measurements were performed at 30 min intervals. Glucose, lactate, pyruvate and glycerol were measured in samples using a CMA 600 Analyser (CMA/Microdialysis AB, Sweden). Results in both groups were statistically processed and the groups were compared. RESULTS: Both groups were similar with regards to preoperative characteristics. Dynamic changes of interstitial concentrations of the measured analytes were found in off-pump (group A) and on-pump (group B) patients during the operation. There were no significant differences in dialysate concentrations of glucose and lactate between the groups. Significant differences were detected in pyruvate concentrations, lactate-pyruvate ratio and glycerol concentrations between off-pump versus on-pump patients. Pyruvate concentrations were higher in the off-pump group (p<0.05), the lactate-pyruvate ratios indicating the aerobic/anaerobic metabolism status were lower in the off-pump group (p<0.01) and the values of the concentrations of glycerol were lower in the off-pump group (p<0.01). CONCLUSION: Dynamic changes in the interstitial concentrations of the glucose, glycerol, pyruvate and lactate were found in both groups of patients (off-pump and on-pump). The presented preliminary results suggest that extracorporeal circulation during cardiac operations could compromise skeletal muscle energy metabolism.

Bone formation in cardiac valves: a histopathological study of 128 cases.

In a series of 1,177 patients with surgical valve resection, there were 128 (10.9%) patients with the histological finding of bone and/or cartilage formation (bony metaplasia; heterotopic ossification) in the excised valve (119 aortic, 9 mitral). The incidence was higher in men (12.8%) than in women (8.5%). The bony metaplasia was always associated with valvular calcification. The metaplastic changes were encountered in all types of calcific aortic valve disease (senile, bicuspid valve, post-rheumatic). The marrow of the heterotopic lamellar bone was mostly composed of adipose tissue. Frequently, it showed chronic inflammation with polyclonal plasmocytic infiltration. Complete haematopoiesis was present only rarely.

Posttraumatic pneumopericardium: a sign of severe injury or radiodiagnostic rarity?

We present three cases of pneumopericardium following blunt chest trauma injury. All three patients were victims of road traffic accidents. All had multiple associated injuries and pneumopericardium was found as the additional finding. Pneumopericardium was treated conservatively with thoracic drains placement and patients observation. Transesophageal echocardiography was used as a method of choice for exclusion of cardiac air tamponade. All three patients survived.

Vascular complications of the intra-aortic balloon counterpulsation.

From September 1994 to December 2002, 6,274 cardiosurgery operations were performed at the Department of Cardiac Surgery, University Hospital, Hradec Kralove, Czech Republic. Intra-aortic balloon counterpulsation (IABP) was applied in 192 cases (3.1%). From this group of 192 counterpulsated patients 103 were successfully treated (53.6%); 89 counterpulsated patients (46.4%) died from the surgical procedure (30-day mortality rate). In 5 cases (2.6%) from the group of 192, the IABP was introduced before the operation. Ischemic changes of the limb were observed in 11 cases (5.7%). Significant bleeding occurred at the site of puncture in 6 cases (3.1%). Dissection of the femoral and iliac arteries was found in 2 patients (1.0%), perforation of the iliac artery in 1 case (0.5%). In 2 cases (1.0%) the balloon was led into the venous system. In case report No. 1 an introduction of the balloon under a sclerotic plaque of the descending aorta and iliac artery is described. In case report No. 2 a placement of the balloon in the venous bloodstream is reported.

Use of two parallel oxygenators in a very large patient (2.76 m2) for an acute "A" dissecting aortic aneurysm repair.

The very large patient (weight 142 kg, height 197 cm, body surface 2.76 m2) was referred to acute operation with dissecting type A ascending aortic aneurysm. The calculated blood flow was 6.63 l/min. To anticipate potential difficulties with perfusion and oxygenation two oxygenators connected in parallel were incorporated into the circuit. Bentall procedure with ACB to the RCA was performed. The perfusion was uneventful. Bypass time was 259 minutes, cross clamp time 141 minutes, circulatory arrest 7 minutes. The highest oxygenators gas flow was 2.6 l/min with maximum FiO2 0.42. The use of two in parallel connected oxygenators is a very effective, easy and safe method in such extreme perfusions, offering to the perfusionist a great reserve of oxygenator output.

Transplantation of bone marrow derived progenitor cells in acute myocardial infarction. The first results.

The intracoronary administration of autologous bone marrow cells (BMCs) has been shown to improve the left ventricle function in the course of acute myocardial infarction. Therefore we have started a clinical trial using transplantation of BMCs in the acute phase of myocardial infarction. The aim of our study is to assess the feasibility and safety of this procedure, and effect on the left ventricle function of these patients. We describe the first experience in two patients with acute myocardial infarction reperfused using direct stenting. The aspiration of bone marrow from the sternum provided sufficient amount of the cells for transplantation. No serious ischemia and no changes in coronary artery patency were detected after intracoronary infusion. The left ventricle ejection fraction was increasing throughout the time of three-month follow-up. No other complications (ventricular arrhythmias, reinfarction, thrombus formation) were detected.