A Generic Method for the Reliable Calculation of Large- Scale Fading in an Obstacle-Dense Propagation Environment

The aim of this chapter is to summarize and present recent findings in the field of wireless channel mod- eling that provide a new method for the reliable calculation of the statistical parameters of large-scale variations of the average received signal (shadow fading). This algorithm is theoretically based on a path loss estimation model that incorporates losses due to walls and floors. This has been confirmed to be the most precise mathematical tool for average signal strength prediction for various frequencies of interest and propagation environments. The total path loss is estimated as a sum of two independent attenuation processes: free space loss and losses due to obstacles. This solution allows for a direct and reliable calculation of the deviation of the fluctuations of the average received signal in an obstacle- dense environment

V2I Applications in Highways: How RSU Dimensioning Can Improve Service Delivery

This paper investigates the performance of Vehicle-to-Infrastructure (V2I) services over Vehicular Networks (VANETs) that are assisted by Road Side Units (RSU). More specifically, an analytical study of RSU dimensioning and a respective module is designed and developed in a simulated VANET environment. Two V2I application scenarios (e.g. car crash, spot weather) are considered in order to evaluate the impact of RSUs, vehicles’ size and speed and car crash start time and duration on applications’ performance. It is shown that the VANET network metrics (Packet Loss and Packet Delivery Ratio) are affected by the available MAC Bit rates and application scenarios. Mobility model metrics (Total Busy Time and Total CO2 Emissions) are also affected by the different application scenarios, number and type of vehicles

Anatomical variation of a trifid (trifurcation) lateral root origin of the median nerve

Anatomic variations of the brachial plexus are common. Awareness of these variations is of paramount importance in clinical practice mainly in achieving best results in minimal invasive or surgical procedures. The aim of our study was to depict a case of a trifid lateral root origin of the medial nerve. This anatomical variation in the brachial plexus was encountered after dissection in upper extremities in a 90-year-old male cadaver

Wireless Information-Theoretic Security: Theoretical analysis & experimental measurements with multiple eavesdroppers in an outdoor obstacle-dense MANET

Wireless Information-Theoretic Security (WITS) has been suggested as a robust security scheme, especially for infrastructure-less networks. Based on the physical layer, WITS considers quasi-static Rayleigh fading instead of the classic Gaussian wiretap scenario. In this paper, they key parameters of WITS are investigated by implementing an 802.11n ad-hoc network in an outdoor obstacle-dense topology. Measurements performed throughout the topology allow for a realistic evaluation of a scenario with multiple moving eavesdroppers. Low speed user movement has been considered, so that Doppler spread can be discarded. A set of discrete field test trials have been conducted, based on simulation of human mobility throughout an obstacle-constrained environment. Average Signal-to-Noise Ratio (SNR) values have been measured for all moving nodes, and the Probability of Non-Zero Secrecy Capacity has been calculated for different eavesdropping cooperative schemes (Selection Combining and Maximal-Ratio Combining). In addition, the Outage Probability has been estimated with regard to a nonzero target Secrecy Rate for both techniques. The results have been compared with the respective values of WITS key parameters derived from theoretical analysis

Case series and a systematic review concerning the level of the aortic bifurcation

Background: The aim of this study is to present the level of aortic bifurcation in a sample of Greek origin (case series) and to perform an up-to-date systematic review in the existing literature. Materials and methods: Seventy-six formalin-fixed adult cadavers were dissected and studied in order to research the level of aortic bifurcation. Additionally, PubMed and Google Scholar databases were searched for eligible articles concerning the level of aortic bifurcation for the period up to February 2020. Results: The mean level of aortic bifurcation according to our case series was the lower third of the L4 vertebral body (21/76, 27.6%). The level of aortic bifurcation ranged between the lower third of the L3 vertebral body and the lower third of the L5 body. No statistically significant correlation was found between the two sexes. The systematic review of the literature revealed 31 articles which were considered eligible and a total number of 3537 specimens were retracted. According to the recorded findings the most common mean level of aortic bifurcation was the body of L4 vertebra (1495/3537 cases, 42.2%), while the range of aortic bifurcation was described to occur from upper third of L3 vertebrae to the upper third of the S1 vertebrae in the 52.8% of the cases (1866/3537). Conclusions: The mean level of AA corresponds to the body of L4 and presents a great range (form L3U to S1U). Knowledge of the mean level of aortic bifurcation and its probable ranges is of great significance for interventional radiologists and especially vascular surgeons that deal with aneurism proximal to the aortic bifurcation

Anatomical variations of the pelvis during abdominal hysterectomy for benign conditions

Background: Anatomical variations are defined as atypical morphologic and positional presentations of anatomical entities. Pelvic anatomical variations encountered during abdominal hysterectomy can be of clinical interest, given that misidentification of certain structures can lead to iatrogenic injuries and postoperative sequelae. The aim of the present study was to detect and highlight the anatomical structures of interest and their variations to the surgeon performing abdominal hysterectomy for benign conditions. Materials and methods: A narrative review of the literature was performed including reports of anatomical variations encountered in cadavers, by surgeons during abdominal hysterectomy and radiologists on computed tomography angiography, searching within a 10-year span on Pubmed database. Studies regarding the treatment of malignant conditions requiring lymphadenectomy and different modes of surgical approach were reviewed with regards to the aspects relevant to benign conditions. The search was extended to the reference lists of all retrieved articles. Results: Ureters and the uterine arteries, due to anatomical variations, are the anatomical structures most vulnerable during abdominal hysterectomy. Specifically, the ureters can present multiplications, retroiliac positionings and ureteric diverticula, whereas, the uterine arteries can present notable variability in their origins. Such variations can be detected preoperatively or intraoperatively. Conclusions: Although rare, the presence of anatomical variations of the uterine arteries and ureters can increase the posibility of complications should they escape detection. Intraoperative misidentification could lead to improper dissection or ligation of the affected structures. Knowledge of these variations, coupled with extensive preoperative investigation and intraoperative vigilance can minimize the risk of complications

Agenesis of the coeliac trunk: a case report and review of the literature

Vascular anatomical variations of the abdomen are very common. Awareness of these variations is of paramount importance in clinical practice mainly in achieving best results in minimal invasive or surgical vascular procedures. From surgical point of view, the preoperative knowledge of vascular anatomy and the relations to the surrounding structures and tissues aims to minimise inadvertent complications. Agenesis of the coeliac trunk is one of the rare anatomical variations of the abdominal aorta. Limited number of cases have been reported in the medical literature, most of which are based on angiographic and cadaveric studies of adult humans. In this paper, we report a case of absence of the coeliac trunk that has been detected as an incidental radiological finding in a female patient who was admitted with abdominal pain

Primary pigmented nodular adrenocortical disease presenting with a unilateral adrenocortical nodule treated with bilateral laparoscopic adrenalectomy: a case report

<p>Abstract</p> <p>Introduction</p> <p>Primary pigmented nodular adrenocortical disease is a rare cause of adrenocorticotropic hormone-independent Cushing's syndrome. We report an uncommon primary pigmented nodular adrenocortical disease case presenting with a unilateral adrenocortical nodule and provide a brief overview of the existing literature.</p> <p>Case presentation</p> <p>A 27-year-old Caucasian woman was admitted to our Department with adrenocorticotropic hormone-independent Cushing's syndrome. Its cause was initially considered a left adrenocortical adenoma based on computer tomography imaging. The patient underwent left laparoscopic adrenalectomy and histological examination revealed pigmented micronodular adrenal hyperplasia. Evaluation for the presence of Carney complex was negative. Six months later recurrence of hypercortisolism was documented and a right laparoscopic adrenalectomy was performed further establishing the diagnosis of primary pigmented nodular adrenocortical disease. After a nine-year follow-up there is no evidence of residual disease.</p> <p>Conclusions</p> <p>Even though primary pigmented nodular adrenocortical disease is a rare cause of Cushing's syndrome, it should be included in the differential diagnosis of adrenocorticotropic hormone-independent Cushing's syndrome, especially because adrenal imaging can be misleading mimicking other adrenocortical diseases. Bilateral laparoscopic adrenalectomy is the preferred treatment in these subjects.</p

Correction to: Two years later: Is the SARS-CoV-2 pandemic still having an impact on emergency surgery? An international cross-sectional survey among WSES members

Background: The SARS-CoV-2 pandemic is still ongoing and a major challenge for health care services worldwide. In the first WSES COVID-19 emergency surgery survey, a strong negative impact on emergency surgery (ES) had been described already early in the pandemic situation. However, the knowledge is limited about current effects of the pandemic on patient flow through emergency rooms, daily routine and decision making in ES as well as their changes over time during the last two pandemic years. This second WSES COVID-19 emergency surgery survey investigates the impact of the SARS-CoV-2 pandemic on ES during the course of the pandemic. Methods: A web survey had been distributed to medical specialists in ES during a four-week period from January 2022, investigating the impact of the pandemic on patients and septic diseases both requiring ES, structural problems due to the pandemic and time-to-intervention in ES routine. Results: 367 collaborators from 59 countries responded to the survey. The majority indicated that the pandemic still significantly impacts on treatment and outcome of surgical emergency patients (83.1% and 78.5%, respectively). As reasons, the collaborators reported decreased case load in ES (44.7%), but patients presenting with more prolonged and severe diseases, especially concerning perforated appendicitis (62.1%) and diverticulitis (57.5%). Otherwise, approximately 50% of the participants still observe a delay in time-to-intervention in ES compared with the situation before the pandemic. Relevant causes leading to enlarged time-to-intervention in ES during the pandemic are persistent problems with in-hospital logistics, lacks in medical staff as well as operating room and intensive care capacities during the pandemic. This leads not only to the need for triage or transferring of ES patients to other hospitals, reported by 64.0% and 48.8% of the collaborators, respectively, but also to paradigm shifts in treatment modalities to non-operative approaches reported by 67.3% of the participants, especially in uncomplicated appendicitis, cholecystitis and multiple-recurrent diverticulitis. Conclusions: The SARS-CoV-2 pandemic still significantly impacts on care and outcome of patients in ES. Well-known problems with in-hospital logistics are not sufficiently resolved by now; however, medical staff shortages and reduced capacities have been dramatically aggravated over last two pandemic years

V2I Applications in Highways: How RSU Dimensioning Can Improve Service Delivery

This paper investigates the performance of Vehicle-to-Infrastructure (V2I) services over Vehicular Networks (VANETs) that are assisted by Road Side Units (RSU). More specifically, an analytical study of RSU dimensioning and a respective module is designed and developed in a simulated VANET environment. Two V2I application scenarios (e.g. car crash, spot weather) are considered in order to evaluate the impact of RSUs, vehicles’ size and speed and car crash start time and duration on applications’ performance. It is shown that the VANET network metrics (Packet Loss and Packet Delivery Ratio) are affected by the available MAC Bit rates and application scenarios. Mobility model metrics (Total Busy Time and Total CO2 Emissions) are also affected by the different application scenarios, number and type of vehicles