Number Systems for Deep Neural Network Architectures: A Survey

Deep neural networks (DNNs) have become an enabling component for a myriad of artificial intelligence applications. DNNs have shown sometimes superior performance, even compared to humans, in cases such as self-driving, health applications, etc. Because of their computational complexity, deploying DNNs in resource-constrained devices still faces many challenges related to computing complexity, energy efficiency, latency, and cost. To this end, several research directions are being pursued by both academia and industry to accelerate and efficiently implement DNNs. One important direction is determining the appropriate data representation for the massive amount of data involved in DNN processing. Using conventional number systems has been found to be sub-optimal for DNNs. Alternatively, a great body of research focuses on exploring suitable number systems. This article aims to provide a comprehensive survey and discussion about alternative number systems for more efficient representations of DNN data. Various number systems (conventional/unconventional) exploited for DNNs are discussed. The impact of these number systems on the performance and hardware design of DNNs is considered. In addition, this paper highlights the challenges associated with each number system and various solutions that are proposed for addressing them. The reader will be able to understand the importance of an efficient number system for DNN, learn about the widely used number systems for DNN, understand the trade-offs between various number systems, and consider various design aspects that affect the impact of number systems on DNN performance. In addition, the recent trends and related research opportunities will be highlightedComment: 28 page

Wear debris pseudotumor following total knee arthroplasty: a case report

<p>Abstract</p> <p>Introduction</p> <p>In patients who have undergone a total joint replacement, any mass occurring in or adjacent to the joint needs thorough investigation and a wear debris-induced cyst should be suspected.</p> <p>Case presentation</p> <p>An 81-year-old man presented with a painful and enlarging mass at the popliteal fossa and calf of his right knee. He had had a total right knee replacement seven years previously. Plain radiographs showed narrowing of the medial compartment. Magnetic resonance imaging showed a cystic lesion at the postero-medial aspect of the knee joint mimicking popliteal cyst or soft tissue sarcoma. Fine needle aspiration was non-diagnostic. A core-needle biopsy showed metallosis. Intraoperative findings revealed massive metallosis related to extensive polyethylene wear, delamination and deformation. Revision knee and patella arthroplasty was carried out after a thorough debridement of the knee joint.</p> <p>Conclusion</p> <p>Long-term follow-up is critical for patients with total joint replacement for early detection of occult polyethylene wear and prosthesis loosening. In these cases, revision arthroplasty may provide a satisfactory knee function.</p

Arthroplasty versus internal fixation for femoral neck fractures in the elderly

We studied 140 patients with femoral neck fractures treated from January 1999 to December 2006. There were 68 men and 72 women with a mean age of 72 years (range 60–80 years). Seventy patients were treated with closed reduction and internal fixation (group A), and 70 patients with hip arthroplasty (group B). The duration of surgery, length of hospitalization, complications, postoperative Harris hip score, and need for reoperation were recorded. Group B had significantly higher blood loss, increased surgical time and length of hospitalization compared to group A patients. The Harris hip score was significantly higher in group B at the 3, 6, and 12-month follow-up evaluations; however, the differences were no longer significant at the 24-month evaluation. The overall complications rate was 18.6% (13 patients) in group A compared to 25.7% (18 patients) in group B; this was not statistically significant (P = 0.309). A statistically significant difference was found regarding reoperation rate in group A (11.4%, eight patients) compared to group B (1.4%, one patient) (P = 0.016). Arthroplasty compared to internal fixation for displaced femoral neck fractures is associated with a significantly higher functional score and lower risk of reoperation at the cost of greater infection rates, blood loss, and operative time

Postoperative spinal infection mimicking systemic vasculitis with titanium-spinal implants

<p>Abstract</p> <p>Background</p> <p>Secondary systemic vasculitis after posterior spinal fusion surgery is rare. It is usually related to over-reaction of immune-system, to genetic factors, toxicity, infection or metal allergies.</p> <p>Case Description</p> <p>A 14 year-old girl with a history of extended posterior spinal fusion due to idiopathic scoliosis presented to our department with diffuse erythema and nephritis (macroscopic hemuresis and proteinuria) 5 months post surgery. The surgical trauma had no signs of inflammation or infection. The blood markers ESR and CRP were increased. Skin tests were positive for nickel allergy, which is a content of titanium alloy. The patient received corticosteroids systematically (hydrocortisone 10 mg) for 6 months, leading to total recess of skin and systemic reaction. However, a palpable mass close to the surgical wound raised the suspicion of a late infection. The patient had a second surgery consisting of surgical debridement and one stage revision of posterior spinal instrumentation. Intraoperative cultures were positive to Staphylococcus aureus. Intravenous antibiotics were administered. The patient is now free of symptoms 24 months post revision surgery without any signs of recurrence of either vasculitis or infection.</p> <p>Literature Review</p> <p>Systemic vasculitis after spinal surgery is exceptionally rare. Causative factors are broad and sometimes controversial. In general, it is associated with allergy to metal ions. This is usually addressed with metal on metal total hip bearings. In spinal surgery, titanium implants are considered to be inert and only few reports have presented cases with systemic vasculitides. Therefore, other etiologies of immune over-reaction should always be considered, such as drug toxicity, infection, or genetic predisposition.</p> <p>Purposes and Clinical Relevance</p> <p>Our purpose was to highlight the difficulties during the diagnostic work-up for systemic vasculitis and management in cases of posterior spinal surgery.</p

Breast cancer management pathways during the COVID-19 pandemic: outcomes from the UK ‘Alert Level 4’ phase of the B-MaP-C study

Abstract: Background: The B-MaP-C study aimed to determine alterations to breast cancer (BC) management during the peak transmission period of the UK COVID-19 pandemic and the potential impact of these treatment decisions. Methods: This was a national cohort study of patients with early BC undergoing multidisciplinary team (MDT)-guided treatment recommendations during the pandemic, designated ‘standard’ or ‘COVID-altered’, in the preoperative, operative and post-operative setting. Findings: Of 3776 patients (from 64 UK units) in the study, 2246 (59%) had ‘COVID-altered’ management. ‘Bridging’ endocrine therapy was used (n = 951) where theatre capacity was reduced. There was increasing access to COVID-19 low-risk theatres during the study period (59%). In line with national guidance, immediate breast reconstruction was avoided (n = 299). Where adjuvant chemotherapy was omitted (n = 81), the median benefit was only 3% (IQR 2–9%) using ‘NHS Predict’. There was the rapid adoption of new evidence-based hypofractionated radiotherapy (n = 781, from 46 units). Only 14 patients (1%) tested positive for SARS-CoV-2 during their treatment journey. Conclusions: The majority of ‘COVID-altered’ management decisions were largely in line with pre-COVID evidence-based guidelines, implying that breast cancer survival outcomes are unlikely to be negatively impacted by the pandemic. However, in this study, the potential impact of delays to BC presentation or diagnosis remains unknown

Reconstruction of diaphyseal segmental defects of long bones: Comparative biomechanical study of stability using metallic titanium prostheses versus allografts

Objective: To compare quantitative data on the biomechanical analysis of different techniques for fixation of intercalary bone defects, by means of consistently applied methodology on composite models of the adult femur, tibia and humerus. Method: A total of fifteen femoral, fifteen tibial and fifteen humeral specimens of fourth generation composite models were used. An intercalary defect (middle 1/5 of the length of each model) was created and was reconstructed using plates, intramedullary nails, external fixators and segmental prosthetic implants. The specimens were loaded under axial compression, four-point-bending and torsion in the linear elastic region at sub-yield level. Results: The analysis for the femur showed no statistically significant differences in the ranking of techniques (p=0.088). The analysis for the tibia revealed a statistically significant difference between groups (p=0.035) with the plate construct ranking lower than the intact. The analysis for the humerus showed statistically significant differences between groups (p=0.038) with the intramedullary nail and plate constructs ranking lower than intact. Conclusions: Modular segmental implants and external fixator ranked better than other techniques, being the ones always exhibiting the most enhanced performance in comparison to intact specimen.Σκοπός: Η σύγκριση των ποσοτικών δεδομένων που προέρχονται από την εµβιοµηχανική ανάλυση διαφορετικών τεχνικών ανακατασκευής οστικών ελλειµµάτων διάφυσης των µακρών οστών σε συνθετικά οστικά μοντέλα μηριαίου, κνήμης και βραχιονίου µε τη χρήση συστηματικά εφαρμοζόμενης μεθοδολογίας. Υλικά & Μέθοδος: Χρησιμοποιήσαμε συνθετικά μοντέλα οστών 4ης γενιάς για την πραγματοποίηση του πειράματός µας και συγκεκριμένα 15 μοντέλα μηριαίου, 15 κνήμης και 15 βραχιονίου. Κρατήσαμε 3 ακέραια μοντέλα από κάθε οστό και στα υπόλοιπα δημιουργήσαμε ένα οστικό έλλειμα στη διάφυση του κάθε οστού μήκους ίσου µε το 1/5 του μήκους της διάφυσης. Τα οστικά ελλείμματα ανακατασκευάστηκαν χρησιμοποιώντας πλάκες εσωτερικής οστεοσύνθεσης, ενδοµυελικούς ήλους, εξωτερικές οστεοσυνθέσεις και συναρµολογούµενες ενδοπροθέσεις διαφυσιακών ελλειµµάτων. Τα δοκίμια στη συνέχεια φορτίστηκαν σε αξονική συµπίεση, κάµψη 4 σηµείων και στρέψη στην περιοχή ελαστικής παραμόρφωσης των δοκιμίων και προσπαθήσαμε να διαπιστώσουμε την ύπαρξη ή µη στατιστικά σημαντικών διαφορών σε σχέση µε τις τιμές των δεχόμενων φορτίων σε κάθε δοκιμασία φόρτισης και τις τιμές ακαμψίας των δοκιμίων σε σχέση µε το ακέραιο οστικό μοντέλο. Αποτελέσματα: Η ανάλυση για το μηριαίο έδειξε ότι δεν υπάρχουν στατιστικά σημαντικές διαφορές στην ιεράρχηση των τεχνικών (p=0.088). Για το μοντέλο της κνήμης αποκαλύφθηκε μια στατιστικά σημαντική διαφορά µμεταξύ των ομάδων (p=0.035) µε την πλάκα να λαμβάνει τη χειρότερη θέση σε σχέση µε τις υπόλοιπες μεθόδους. Η ανάλυση για το βραχιόνιο έδειξε μια στατιστικά σημαντική διαφορά μεταξύ των ομάδων (p=0.038) µε τον ήλο και την πλάκα να έχουν χειρότερη εµβιοµηχανική συμπεριφορά σε σχέση µε το ακέραιο μοντέλο. Συμπεράσματα: Οι ενδοπροθέσεις ανακατασκευής διαφυσιακών τμηματικών ελλειμμάτων και τα συστήματα εξωτερικής οστεοσύνθεσης συμπεριφέρονταν καλύτερα εµβιοµηχανικά σε σχέση µε τις υπόλοιπες 2 τεχνικές

Influence of soil properties and seasonal changes on the behaviour of grounding systems

157 σ.Σκοπός της παρούσας διπλωματικής εργασίας είναι η συμβολή στη μελέτη της επίδρασης του μικροεδάφους και των εποχικών μεταβολών στη συμπεριφορά συστημάτων γείωσης. Για την επίτευξη της μελέτης αυτής, διεξάγονταν δύο με τρεις φορές την εβδομάδα, κατά μέσο όρο, in situ μετρήσεις εντός της Πολυτεχνειούπολης Ζωγράφου, της ειδικής αντίστασης του φυσικού εδάφους και της αντίστασης γείωσης πέντε ράβδων γείωσης μήκους 1,5m, εκ των οποίων το ένα είναι το ηλεκτρόδιο αναφοράς και είναι εμπηγμένο στο φυσικό έδαφος, ενώ τα άλλα τέσσερα ηλεκτρόδια είναι εμβαπτισμένα σε τέσσερα διαφορετικά βελτιωτικά υλικά γειώσεων. Ύστερα από κατάλληλη επεξεργασία των μετρήσεων που ελήφθησαν στα πλαίσια της διπλωματικής αυτής, αλλά και όλων των προηγούμενων από την 17η Φεβρουαρίου 2011, οπότε και ξεκίνησε η διεξαγωγή μετρήσεων στην πειραματική διάταξη, τα αποτελέσματα παρουσιάζονται λεπτομερώς, σε μορφή διαγραμμάτων ποικίλων τύπων, κυρίως σε συνάρτηση με τη μεταβολή του χρόνου και το ύψος της βροχής. Μέσω της μελέτης των αποτελεσμάτων των μετρήσεων προκύπτουν σημαντικά συμπεράσματα σχετικά με τη μεταβολή της ειδικής αντίσταση ς του εδάφους και της αντίστασης γείωσης των ηλεκτροδίων, σε συνάρτηση με το χρόνο, διερευνώνται οι παράγοντες που τις επηρεάζουν, όπως είναι το ύψος βροχής, η συχνότητα των βροχοπτώσεων, οι εποχικές και καιρικές μεταβολές, η περιεκτικότητα (%) του εδάφους σε υγρασία και σε ό,τι αφορά την αντίσταση γείωσης, η χρήση βελτιωτικών υλικών γειώσεων. Τέλος, πραγματοποιείται μια διεξοδική ανάλυση της συμπεριφοράς των τεσσάρων βελτιωτικών υλικών (σκυρόδεμα θεμελιώσεων, μπετονίτης, χημικό υλικό Α, χημικό υλικό Β) και αξιολογούνται ως προς την αποτελεσματικότητά τους.The aim of this diploma thesis is to contribute to the determination of the ways that soil properties and seasonal changes affect the behaviour of grounding systems. In order to achieve the aforementioned, field measurements of soil resistivity and of the grounding resistance of five rods (length 1,5m), of which one was driven in the natural soil, and the other four in different ground enhancing compounds, were conducted two to three times per week, on average. The measurement results, not only from the period in which this current thesis was conducted, but also from the beginning of this experiment on the 17th of February 2011, are presented in various diagrams, mostly in relation to time and to rainfall. After thorough investigation of the measurement results, significant conclusions can be made regarding the change of soil resistivity and grounding resistance of the grounding electrodes as a function of time, by examining the factors that influence them, such as rainfall, frequency of rainfall, the seasonal and weather changes, soil moisture and only for the case of grounding resistance, the usage of ground enhancement compounds. Finally in the context of this thesis takes place an in depth analysis of the behaviour of the four ground enhancing materials (conductive concrete, bentonite, chemical compound A, chemical compound B) and they are evaluated for their effectiveness.Αυγερινός-Βασίλειος Ι. Σακελλαρίο

Negative-Pressure Wound Therapy for Musculoskeletal Tumor Surgery

OBJECTIVE: To evaluate the effect of negative-pressure wound therapy in musculoskeletal tumor surgery patients. MATERIALS AND METHODS: The authors analyzed the medical records of 32 patients treated at the authors’ institution for bone and soft-tissue sarcomas and secondary wound-healing complications, from 2005 to 2008; there were 11 men and 21 women, with a mean age of 56 years (range, 35-72 years). RESULTS: A statistically significant difference (P = .036) was found regarding the length of hospitalization in the conventional wound treatment group, group A (mean, 25.2 days; range, 15-52 days), compared with the negative wound pressure therapy group, group B (mean, 16.5 days; range, 12-33 days). CONCLUSIONS: The use of negative-pressure wound therapy for the management of complicated wound healing in sarcoma patients following tumor surgery is safe and effective and is associated with lower overall complications rates, infection rate, and the need for further surgery and a lower total cost of wound-healing treatment

Late Mycobacterium bovis spondylitis after intravesical BCG therapy

A 72-year-old man presented with a 6-month history of low back and leg pain. Past medical history revealed transurethral resection of bladder cancer followed by multiple intravesical BCG instillation 12 years ago. Imaging studies of the thoracolumbar spine showed osteolysis of the L3 and L4 vertebrae and the associated intervertebral disc space, and a large soft tissue mass with signal abnormalities suggesting of an abscess. CT-guided needle biopsy showed Mycobacterium bovis infection. A triple anti-tuberculous chemotherapy regimen including isoniazid, rifampicin, and ethambutol was administered for 12 months. Surgical treatment included drainage of the abscess and L2-L5 spinal instrumentation and fusion. Intravesical BCG therapy may be complicated by late disseminated disease to the bone even many years after initial BCG therapy. Patients having BCG therapy should be closely evaluated thereafter for the possibility of hematogenous spread of mycobacteria to distant sites. (C) 2009 Published by Elsevier Masson SAS on behalf of the Societe Francaise de Rhumatologie