Robust Linear Regression Analysis - A Greedy Approach

The task of robust linear estimation in the presence of outliers is of particular importance in signal processing, statistics and machine learning. Although the problem has been stated a few decades ago and solved using classical (considered nowadays) methods, recently it has attracted more attention in the context of sparse modeling, where several notable contributions have been made. In the present manuscript, a new approach is considered in the framework of greedy algorithms. The noise is split into two components: a) the inlier bounded noise and b) the outliers, which are explicitly modeled by employing sparsity arguments. Based on this scheme, a novel efficient algorithm (Greedy Algorithm for Robust Denoising - GARD), is derived. GARD alternates between a least square optimization criterion and an Orthogonal Matching Pursuit (OMP) selection step that identifies the outliers. The case where only outliers are present has been studied separately, where bounds on the \textit{Restricted Isometry Property} guarantee that the recovery of the signal via GARD is exact. Moreover, theoretical results concerning convergence as well as the derivation of error bounds in the case of additional bounded noise are discussed. Finally, we provide extensive simulations, which demonstrate the comparative advantages of the new technique

Open type ferry safety systems design for using LNG fuel

This feasibility study investigates the viability of employing Liquefied Natural Gas (LNG) fuel to an open type Ro-Ro passenger ferry and the potential challenges imposed with regard to the vessel safety systems. The study proposes appropriate methodology for converting the existing ship to run on LNG fuel and discusses all the necessary modifications to the ship’s safety systems; furthermore, the ship’s evacuation analysis is investigated accordingly. The basic requirements that the ship already complies with are initially reported for each safety system while the additional restrictions that need to be taken into consideration for employing LNG fuel are analysed; appropriate actions are proposed. Furthermore, a Hazard Identification Study (HAZID) is also carried out. Overall, the technical feasibility of the investigated scenario is clearly demonstrated; minimal modifications to the ship's safety systems in order to comply with the imposed safety rules are required for the specific type of ship

Intraoperative Multispectral Fluorescence Imaging for the Detection of the Sentinel Lymph Node in Cervical Cancer: A Novel Concept

PURPOSE: Real-time intraoperative near-infrared fluorescence (NIRF) imaging is a promising technique for lymphatic mapping and sentinel lymph node (SLN) detection. The purpose of this technical feasibility pilot study was to evaluate the applicability of NIRF imaging with indocyanin green (ICG) for the detection of the SLN in cervical cancer. PROCEDURES: In ten patients with early stage cervical cancer, a mixture of patent blue and ICG was injected into the cervix uteri during surgery. Real-time color and fluorescence videos and images were acquired using a custom-made multispectral fluorescence camera system. RESULTS: Real-time fluorescence lymphatic mapping was observed in vivo in six patients; a total of nine SLNs were detected, of which one (11%) contained metastases. Ex vivo fluorescence imaging revealed the remaining fluorescent signal in 11 of 197 non-sentinel LNs (5%), of which one contained metastatic tumor tissue. None of the non-fluorescent LNs contained metastases. CONCLUSIONS: We conclude that lymphatic mapping and detection of the SLN in cervical cancer using intraoperative NIRF imaging is technically feasible. However, the technique needs to be refined for full applicability in cervical cancer in terms of sensitivity and specificity

Ανάπτυξη νέας μεθόδου απεικονιστικής φασματοσκοπίας για την in-vivo διάγνωση καρκινικών και προκαρκινικών καταστάσεων σε επιθηλιακούς ιστούς, βασισμένη στην ποσοτική αξιολόγηση της αλληλεπίδρασης του οξικού οξέος με τον ιστό

Cervical cancer is the commonest form of cancer in females under 35 years of age and the second most common in females of all ages. Limitations of the existing diagnostic methods have led to the development of new diagnostic approaches. Acetic acid is a marker used for more than 70 years in gynecology for the detection of abnormal lesions. Local application of acetic acid causes a temporal whiting to abnormal areas (acetowhite) while normal areas are not affected. Extensive clinical trials have shown that the visual assessment of acetowhitening exhibits similar diagnostic performance to other methods such as Test Pap. The diagnostic method proposed in this project is based on the quantitative and objective assessment of the acetic acid-tissue interaction by means of an Imaging Spectroscopy System. For the purpose of this study a new Imaging Spectroscopy system has been designed and developed. The method was used for the in vivo detection of dysplasias in the cervix and the results, from measurements of 181 women, indicated that there is a strong correlation between the histological condition of the tissue and the kinetics of the acetowhitening development. The best fit of the time course measurements of acetowhitening was achieved by the triple exponential function. Statistical analysis of several parameters that characterize the acetowhitening kinetics, have indicated that the combined evaluation of the parameters that express the duration (t5) and the intensity of acetowhitening (EDRmax) differentiates sufficiently all the examined histological conditions. Estimation of the sensitivity and the specificity of this method indicates that its diagnostic performance is comparable or better than that of the existing methods. In order to explain the experimental results, a model for the acetic acid-tissue interaction is proposed. According to this model the tissue-pH alterations induced by the application of acetic acid can be simulated with a 3-compartment model (the intracellular, the extracellular and the blood sink compartments). The solution of the model has shown that, after the application of acetic acid, the intracellular pH exhibits the same kinetics with the acetowhitening. The alterations of the intracellular pH cause increment in the relative refractive index of the nuclear proteins, and consequently increase the light scattering by the nuclei. Furthermore, this model correlates qualitatively the kinetics of the acetowhitening with some structural, compositional and functional features of the epithelial tissue and successfully interprets the experimental results. In particular, epithelial tissue features such as the nuclear size and inhomogeneity, the epithelium thickness, the cellular energy reserves (e.g. glycogen), the density of cell-packing, the cellular metabolism, and the efficiency of the vascularity determine the acetowhitening kinetics

Enhancing Surgical Vision by Using Real-Time Imaging of alpha(v)beta(3)-Integrin Targeted Near-Infrared Fluorescent Agent

This study was designed to improve the surgical procedure and outcome of cancer surgery by means of real-time molecular imaging feedback of tumor spread and margin delineation using targeted near-infrared fluorescent probes with specificity to tumor biomarkers. Surgical excision of cancer often is confronted with difficulties in the identification of cancer spread and the accurate delineation of tumor margins. Currently, the assessment of tumor borders is afforded by postoperative pathology or, less reliably, intraoperative frozen sectioning. Fluorescence imaging is a natural modality for intraoperative use by directly relating to the surgeon's vision and offers highly attractive characteristics, such as high-resolution, sensitivity, and portability. Via the use of targeted probes it also becomes highly tumor-specific and can lead to significant improvements in surgical procedures and outcome. Mice bearing xenograft human tumors were injected with alpha(v)beta(3)-integrin receptor-targeted fluorescent probe and in vivo visualized by using a novel, real-time, multispectral fluorescence imaging system. Confirmatory ex vivo imaging, bioluminescence imaging, and histopathology were used to validate the in vivo findings. Fluorescence images were all in good correspondence with the confirming bioluminescence images in respect to signal colocalization. Fluorescence imaging detected all tumors and successfully guided total tumor excision by effectively detecting small tumor residuals, which occasionally were missed by the surgeon. Tumor tissue exhibited target-to-background ratio of similar to 4.0, which was significantly higher compared with white-light images representing the visual contrast. Histopathology confirmed the capability of the method to identify tumor negative margins with high specificity and better prediction rate compared with visual inspection. Real-time multispectral fluorescence imaging using tumor specific molecular probes is a promising modality for tumor excision by offering real time feedback to the surgeon in the operating room

Visualization 1: Simultaneous real-time multicomponent fluorescence and reflectance imaging method for fluorescence-guided surgery

Injection of fluorescent dyes into tissue Originally published in Optics Letters on 15 March 2016 (ol-41-6-1173