All-optical directional coupler switching in chalcogenide glass

Copyright © 2005 IEEEYinlan Ruan, Barry Luther-Davies, Andrei Rode, Vesselin Kolev, Wieslaw Krolikowsk

Positive Semidefiniteness and Positive Definiteness of a Linear Parametric Interval Matrix

We consider a symmetric matrix, the entries of which depend linearly on some parameters. The domains of the parameters are compact real intervals. We investigate the problem of checking whether for each (or some) setting of the parameters, the matrix is positive definite (or positive semidefinite). We state a characterization in the form of equivalent conditions, and also propose some computationally cheap sufficient\,/\,necessary conditions. Our results extend the classical results on positive (semi-)definiteness of interval matrices. They may be useful for checking convexity or non-convexity in global optimization methods based on branch and bound framework and using interval techniques

Interactive Robot for Playing Russian Checkers

Human\u2013robot interaction in board games is a rapidly developing field of robotics. This paper presents a robot capable of playing Russian checkers designed for entertaining, training, and research purposes. Its control program is based on a novel unsupervised self-learning algorithm inspired by AlphaZero and represents the first successful attempt of using this approach in the checkers game. The main engineering challenge in mechanics is to develop a board state acquisition system non-sensitive to lighting conditions, which is achieved by rejecting computer vision and utilizing magnetic sensors instead. An original robot face is designed to endow the robot an ability to express its attributed emotional state. Testing the robot at open-air multiday exhibitions shows the robustness of the design to difficult exploitation conditions and the high interest of visitors to the robot

CLINICAL OUTCOME OF INTERSPHINCTERIC RESECTION FOR ULTRA-LOW RECTAL CANCER

BACKGROUND: Laparoscopic surgery has been reported to be one of the approaches for total mesorectal excision (TME) in rectal cancer surgery. Intersphincteric resection (ISR) has been reported as a promising method for sphincter-preserving operation in selected patients with very low rectal cancer. METHODS: We try to underline the important surgical issues surrounding the management of patients with low rectal cancer indicated to laparoscopic intersphincteric resection (ISR). From January 2007 till now, 35 patients with very low rectal cancer underwent laparoscopic TME with ISR. We report and analyze the results from them RESULTS: Conversion to open surgery was necessary in one (3%) patient. The median operation time was 293 min and median estimated blood loss was 40 ml. The pelvic plexus was completely preserved in 32 patients. There was no mortality. Postoperative complications occurred in three (9%) patients. The median length of postoperative hospital stay was 11 days. Macroscopic complete mesorectal excision was achieved in all cases. Complete resection (R0) was achieved in 21 (91%) patients.CONCLUSIONS: Laparoscopic TME with ISR is technically feasible and a safe alternative to laparotomy with favorable short-term postoperative outcomes. The literature research made by us found that the laparoscopic approach can be underwent in most patients with low rectal cancer in which laparoscopic ISR represents a feasible alternative to conventional open surgery

ASSESSMENT OF THE LEVEL OF MOTOR PREPAREDNESS OF BULGARIAN AND FOREIGN STUDENTS TRAINING AT THE UNIVERSITY OF FORESTRY

The process of managing students' motor level requires solving tasks, such as measuring and evaluating basic qualities, and is the basis of pedagogical activity. The purpose of the study is to evaluate and compare the level of physical preparedness of newly admitted Bulgarian and foreign students. They chose to practice table tennis or volleyball. As a result of a conducting ascertaining pedagogical experiment, the input level of indicators, such as upper and lower extremity explosive strength, grip strength, abdominal muscle strength, the state of sensory systems and the neuromuscular apparatus, the ability of the spine to fold and etc. The results of the sports-pedagogical testing were obtained using mathematical-statistical processing, through a specialized program IBM "SPSS" 19 and "Excel". Variational and comparative analysis have been applied

Early perioperative res ults in 53 cases of locally rec urrent colorectal cancer

Purpose: The objective of this study was to analyze retrospectively the early perioperative results in a cohort of 53 patients with localy reccurent colorectal cancer (CRC).Material and methods: The study covered 53 patients with CRC 21 males and 32 females at a mean age of 62 years treated in the Clinic of Liver, Biliary, Pancreatic and General Surgery, Tokuda Hospital of Sofia, during the period from January 2007 to March 2013. Any necessary diagnostic and surgical methods were applied.Results: The locally recurrent CRC is a challenge for the surgeon because of the fact that in most cases it engages adjacent anatomical structures and organs, on the one hand, and it is accompanied by complications, on the other hand.Conclusion: Achievement of good late results in patients with recurrent CRC is due to radicality of the interventions. Most often, they should be multivisceral resections. The presence of intestinal obstruction of varying degree and of synchronous peritoneal and liver metastases commonly limit the possibilities for surgical interference with the disease. Particular attention should be paid to possible neoadjuvant treatment capable of reducing the stage of diasease and improving the perioperative outcomes. Therapeutic behaviour should be strictly individual and consider any possible options. The experience of the surgical team is extremely important, too

Locally advanced adenocarcinoma of the supramesocolic part of the colon . Feat ures of surgical treatment and challenges

Purpose: The objective of the present study was to analyze the early results from the surgical treatment of locally advanced carcinoma of the colon in its transverse section and the two flexures.Material and methods: The study covered 36 patients with locally advanced colonic carcinoma, 19 males and 17 females at a mean age of 65,6 years, treated in the Clinic of Liver, Biliary, Pancreatic and General Surgery, Tokuda Hospital of Sofia during the period from January 2007 to March 2013. Any necessary diagnostic and surgical methods were applied.Results: Multivisceral resections were commonly performed in order to achieve a radical surgery in cases of locally advanced disease. Great surgeon`s experience in liver, biliary and pancreatic interventions is obligatorily required. In this paper we share our experience in the treatment of this disease for a period of 6 years.Conclusion: Our application of the multivisceral resections results in surgical radicality along with acceptable levels of perioperative morbidity and mortality rates when compared to other studies in in the foreign literature available

Multivisceral ‘en-bloc` resections of colorectal tumours - milestones in the surgical techniques

Purpose: Colorectal tumours (CRT) consisting mainly of colorectal cancer (CRC) are diagnosed sometimes at an advanced T4 stage, i. e. local involvement of neighbouring organ/organs and anatomical structure/ structures. Aggressive surgical approach preceded and/or followed by neo-adjuvant/adjuvant therapy is advocated because of proven benefit for the patient. The aim of this study was to carry out a literature survey, on the one hand, and to analyze the cases from the authors` institutional experience, on the other hand, in an attempt to submit for consideration the milestones of the multivisceral en-block resections in cases of locally advanced CRTs, i.e. to describe the specific surgical approaches depending on different tumour location and peritumoural involvement of adjacent structures and organs.Material and methods: A retrospective analysis of 154 cases of CRT was performed, all of them operated in the Clinic of Liver, Biliary, Pancreatic and General Surgery, Tokuda Hospital of Sofia, from January 1, 2007 to March 31, 2013. All the patients were diagnosed in an advanced T4-stage and received multivisceral en-bloc resections. Three main groups of methods that had been used were analyzed: 1) preoperative diagnosis, giving a hint of multivisceral en-bloc resection; 2) intraoperative assessment - gross tumour appearance, frozen sections (?), final histological examinations, and 3) surgical methods.Results: Early morbidity and mortality rates were 22,6% and 5,8%, respectively, without any significant difference when compared with ‘simple` colon and rectum resections and with literature data available.Conclusion: Multivisceral en-bloc resection for CRCs has been performed in more than 10% of the cases. It benefits the long-term prognosis. Tumour location and number of resected organs are essential characteristics of these procedures and they are independently associated with the quantity of intraoperative blood loss, higher early morbidity rates and more frequent local recurrence

INFLUENCE OF THE FDG-PET/CT ON THE DIAGNOSE AND STAGING OF COLORECTAL CANCER.

INTRODUCTION: In patients with colorectal cancer (CRC), preoperative evaluation and staging should focus on techniques that might alter the preoperative or intraoperative surgical plan. Conventional imaging methods (CT, MRI) have low accuracy for identifying the depth of tumour infiltration and have limited ability to detect regional lymph node involvement. The aim of this study was to evaluate the utility of FDG-PET in the initial staging of patients with CC in comparison with conventional staging methods and to determine its impact on therapeutic management.METHODS: In First Clinic of Surgery at University Hospital “St. Marina” one hundred and four patients with a diagnosis of CRC (53 males and 51 females; mean age 66.76± 12.36 years), selected prospectively. All patients were studied for staging using a standard procedure (CT) and FDG-PET. The reference method was histology. The effect of FDG-PET on the diagnose and the operative treatment was studied.RESULTS: In 14 patients, surgery was contraindicated by FDG-PET owing to the extent of disease (only 6/14 suspected by CT). FDG-PET revealed four synchronous tumours. For N staging, both procedures showed a relatively high specificity but a low diagnostic accuracy (PET 56%, CT 60%) and sensitivity (PET 21%, CT 25%). For M assessment, diagnostic accuracy was 92% for FDGPET and 87% for CT. FDG-PET results led to modification of the therapy approach in 17.85% of the patients with rectal cancer and in 14.8% of the patients with colon cancer.CONCLUSION: Compared with conventional techniques, FDGPET appears to be useful in pre-surgical staging of CC, revealing unsuspected disease and impacting on the treatment approach