Εφαρμογές τρισδιάστατης ανακατασκευής με γεωμετρία πολλών όψεων

278 σ.Η παρούσα διπλωματική εργασία έχει ως αντικείμενο την τρισδιάστατη ανακατασκευή της γεωμετρίας της σκηνής, από δισδιάστατες εικόνες της, με χρήση τεχνικών όρασης υπολογιστών και γεωμετρίας πολλαπλών όψεων. Έμφαση δίνεται σε εξωτερικές αρχιτεκτονικές σκηνές και επιχειρείται η εφαρμογή των μεθόδων σε χώρους πολιτιστικού ενδιαφέροντος. Αρχικά, αναπτύσσεται μέθοδος ανάκτησης των εσωτερικών (χαρακτηριστικά κάμερας) και εξωτερικών (σχετική θέση φωτογραφιών) παραμέτρων των φωτογραφιών. Η μέθοδος χρησιμοποιεί ζεύγη φωτογραφιών και δεν προβαίνει στην υπόθεση ταυτόσημων εσωτερικών παραμέτρων που συνηθίζεται στην βιβλιογραφία. Στη συνέχεια, η μέθοδος ενσωματώνεται σε κατάλληλα σχεδιασμένα συστήματα τρισδιάστατης ανακατασκευής. Τέλος, η προηγούμενη μέθοδος βελτιώνεται με την αξιοποίηση γεωμετρικών ιδιοτήτων του προβλήματος, στο αρχικό ταίριασμα περιγραφών σημείων (χαρακτηριστικών) των εικόνων και στην εκτίμηση των εξωτερικών και εσωτερικών παραμέτρων των φωτογραφιών. Η αξιοποίηση της γεωμετρικής δομής του προβλήματος οδηγεί σε βελτιωμένα αποτελέσματα και πιο αξιόπιστες μεθόδους. Πέρα από τις συνεισφορές της εργασίας που παρουσιάζονται στο δεύτερο μέρος, τα στάδια και οι καθιερωμένοι αλγόριθμοι τρισδιάστατης ανακατασκευής περιγράφονται με λεπτομέρεια στο πρώτο μέρος.The aim of this thesis is to reconstruct scene's 3D geometry, using its 2Dimages, employing computer vision and multiple view geometry techniques. We focus on outdoor architectural scenes and attempt to reconstruct cultural heritage sites. Initially, we develop a method to recover intrinsic (describing the cameras) and extrinsic (describing relative positions) parameters for each view. The method uses photograph pairs and allows, in contrast with previous approaches, varying internal parameters. Next, we incorporate the previous method to an accordingly designed 3D reconstruction pipeline. Finally, we utilize geometric properties inherent to the reconstruction problem to improve the initial matching between point descriptions (features) as well as the recovery of internal and external camera parameters. That results in improvements in performance and reliability. In addition to our contributions, presented in the second part, we provide a thorough presentation of the various stages and the most influential techniques that constitute a 3D reconstruction pipeline.Νίκος Ε Μελανίτης-Παρασκευά

Axial transformation of the profunda femoris vein: formation, relations and course in a cadaveric specimen

When the superficial femoral vein is obstructed by thrombosis, the profunda femoris vein provides an important collateral pathway, transforming into the axial vein of the lower limb. When operating on a transformed axial vein, a surgeon should be aware of the formation, the relations and the course of the vein. A precise description of these anatomical features is not feasible on the basis of ultrasound, venographic or surgical study but only from anatomical studies. We present a case of axial transformation of the profunda femoris vein found in a cadaver, focusing on the anatomical features of the transformed axial vein

A rare case of bilateral supernumerary heads of sternocleidomastoid muscle and its clinical impact

The sternocleidomastoid muscle (SCM) functions as a landmark for physicians such as anatomists, orthopaedic surgeons, neurosurgeons, and anaesthesiologists, who intervene in the minor supraclavicular fossa located at the base of the neck. The variability of SCM anatomy may cause complications while trying to access the vital elements that are located in the minor supraclavicular fossa. This study aims to present a case of supernumerary heads of the sternocleidomastoid muscle and to discuss its clinical significance. The cervical region of an elderly male cadaver was dissected and the findings were recorded and photographed. On both sides, the SCM muscle had an additional sternal head, and simultaneously there were three additional clavicular heads, four in total. These additional heads, the sternal and the clavicular, reduced the interval between them causing significant stenosis of the minor supraclavicular fossa. Sternocleidomastoid muscle variations with regard to the number of its heads are very rare in the literature, but this variation may cause severe complications. The minor supraclavicular fossa is important for anaesthesiologists because of the anterior central venous catheterization approach. Physicians should be aware of this anatomical variation in order to prevent complication

Laparoscopic Approach to Incarcerated and Strangulated Inguinal Hernias

Introduction: Acute inguinal hernias are a common presentation as surgical emergencies, which have been routinely managed with open surgery. In recent years, the laparoscopic approach has been described by several authors but has been controversial amongst surgeons. We describe the laparoscopic approach to incarcerated/strangulated inguinal hernias based on a review of the literature with regards to its feasibility in laparoscopically managing the acute hernia presentation. Methods: A systematic literature search was carried out including Medline with PubMed as the search engine, and Ovid, Embase, Cochrane Collaboration, and Google Scholar databases to identify articles reporting on laparoscopic treatment, reduction, and repair of incarcerated or strangulated inguinal hernias from 1989 to 2008. Results: Forty-three articles were found, and 7 were included according to the inclusion criteria set. Articles reporting on the use of laparoscopy for the evaluation of the hernia but not reducing and repairing it, the use of the open technique, elective hernia repairs, pediatric series, review articles, and other kinds of hernias were excluded after title and abstract review. This resulted in 16 articles that were reviewed in full. Of these 16 articles, 7 reported on the use of the laparoscopic approach exclusively. From these 7 studies, there were 328 cases reported, 6 conversions, average operating time of 61.3 minutes (SD 12.3), average hospital stay of 3.8 days (SD 1.2), 34 complications (25 of which were reported as minor), and 17 bowel resections performed either laparoscopically or through a minilaparotomy incision guided laparoscopically. Conclusion: The laparoscopic repair is a feasible procedure with acceptable results; however, its efficacy need

Strong-field effects induced in the extreme ultraviolet domain

Motivated by the achieved high intensities of novel extreme ultraviolet (XUV) radiation sources, such as free electron lasers and laser-driven high harmonic generation beamlines, we elaborate on their perspective in inducing observable strong field effects. The feasibility of extending such effects from the infrared and visible spectral regimes in the XUV domain is supported through numerically calculated models of near-future experiments. We highlight the advancement of performing studies in the time domain, using ultra-short XUV pulses, which allows for the temporal evolution of such effects to be followed. Experimental and theoretical obstacles and limitations are further discussed. © The Author(s), 2020. Published by Cambridge University Press in association with Chinese Laser Press

Clinical, Neuroimaging, and Genetic Markers in Cerebral Amyloid Angiopathy-Related Inflammation: A Systematic Review and Meta-Analysis

Background: There are limited data regarding the prevalence of distinct clinical, neuroimaging and genetic markers among patients diagnosed with cerebral amyloid angiopathy-related inflammation (CAA-ri). We sought to determine the prevalence of clinical, radiological, genetic and cerebrospinal fluid biomarker findings in patients with CAA-ri. Methods: A systematic review and meta-analysis of published studies including patients with CAA-ri was conducted to determine the prevalence of clinical, neuroimaging, genetic and cerebrospinal fluid biomarker findings. Subgroup analyses were performed based on (1) prospective or retrospective study design and (2) CAA-ri diagnosis with or without available biopsy. We pooled the prevalence rates using random-effects models and assessed the heterogeneity using Cochran-Q and I2-statistics. Results: We identified 4 prospective and 17 retrospective cohort studies comprising 378 patients with CAA-ri (mean age, 71.5 years; women, 52%). The pooled prevalence rates were as follows: cognitive decline at presentation 70% ([95% CI, 54%-84%]; I2=82%), focal neurological deficits 55% ([95% CI, 40%-70%]; I2=82%), encephalopathy 54% ([95% CI, 39%-68%]; I2=43%), seizures 37% ([95% CI, 27%-49%]; I2=65%), headache 31% ([95% CI, 22%-42%]; I2=58%), T2/fluid-attenuated inversion recovery-hyperintense white matter lesions 98% ([95% CI, 93%-100%]; I2=44%), lobar cerebral microbleeds 96% ([95% CI, 92%-99%]; I2=25%), gadolinium enhancing lesions 54% ([95% CI, 42%-66%]; I2=62%), cortical superficial siderosis 51% ([95% CI, 34%-68%]; I2=77%) and lobar macrohemorrhage 40% ([95% CI, 11%-73%]; I2=88%). The prevalence rate of the ApoE (Apolipoprotein E) ϵ4/ϵ4 genotype was 34% ([95% CI, 17%-53%]; I2=76%). Subgroup analyses demonstrated no differences in these prevalence rates based on study design and diagnostic strategy. Conclusions: Cognitive decline was the most common clinical feature. Hyperintense T2/fluid-attenuated inversion recovery white matter lesions and lobar cerebral microbleeds were by far the most prevalent neuroimaging findings. Thirty-four percent of patients with CAA-ri have homozygous ApoE ϵ4/ϵ4 genotype and scarce data exist regarding the cerebrospinal fluid biomarkers and its significance in these patients