1,720,964 research outputs found
Previsione idrologica per la gestione degli impianti idroelettrici
Full text linkNel presente lavoro è descritto un modello idrologico a parametri concentrati ideato per migliorare i sistemi di previsione per la produzione idroelettrica. Particolare enfasi è data alla struttura del modello e alla metodologia di calibrazione adottata. In particolare, viene presentato un approccio mirato a scomporre le fasi di calibrazione in funzione dei processi da simulare. Tale approccio ha consentito di definire una struttura di modello robusta in grado di fornire buone stime del deflusso in alveo a supporto del collocamento nella borsa elettrica dell’energia prodotta. Il modello è stato utilizzato sul bacino del Fiume Aniene per generare previsioni di tipo deterministico. Queste analisi sono servite per valutare l’attendibilità delle previsioni con tempi di preavviso di 1, 2 e 3 giorni. I risultati mostrano un buon livello di affidabilità delle previsioni con un giorno di anticipo, mentre gli errori delle previsioni a 2 e 3 aumentano in modo più marcato
Peritoneal carcinomatosis from ovarian cancer: the role of CT and [18F]FDG-PET/CT
No full textPURPOSE: The diagnosis of peritoneal carcinomatosis secondary to ovarian cancer is a real challenge in the cancer imaging field. In this retrospective study, we evaluate the accuracy of Single Detector Computed Tomography (SDCT), Multi Detector Computed Tomography (MDCT), and Positron Emission Tomography-Computed Tomography with F18-fluorodeoxyglucose ([18F]FDG-PET/CT) in the diagnosis of peritoneal seeding and we evaluate the possible applications of MDCT to predict the complete surgical removal of the peritoneal deposits.
METHODS AND MATERIALS: A total of 228 scans (91 SDCT, 89 MDCT, and 48 [18F]FDG-PET/CT) of patients with peritoneal carcinomatosis secondary to ovarian cancer proved at laparoscopy and confirmed by histopathology were retrospectively reviewed by two independent groups of Radiologists and Nuclear Medicine Physicians for the evaluation of ascites, peritoneal nodules, and omental cake signs.
RESULTS: MDCT showed 81% of true positives, SDCT 72.5%, and [18F]FDG-PET/CT 77%. False negatives were 19% for MDCT, 27.5% for SDCT, and 23% for [18F]FDG-PET/CT.
CONCLUSION: From our results, we concluded that MDCT is the technique of choice in the diagnosis of peritoneal seeding, while [18F]FDG-PET/CT, though showing similar accuracy, remains the most accurate technique for monitoring therapeutic response and disease recurrence. MDCT could play an important role due to its ability to predict the possibility of complete surgical removal of disease thus influencing the treatment plan aimed to improve quality of life
Solitary fibrous tumours : unusual aspects of a rare disease
Full text linkBackground: In literature there are only a few descriptions of the typical presentation of solitary fibrous tumours (SFT) and only a few case reports showing its unusual clinical and radiological features. Methods: We retrospectively evaluated the computed tomography scans of 36 patients presenting with a histological diagnosis of SFT between 1998 and 2008. Results: We present five cases of SFT with an atypical clinical presentation and radiological features. Conclusions: SFT can occasionally present with unusual radiological features making a differential diagnosis difficult. Even thought imaging plays a fundamental role in the initial diagnostic approach, final diagnosis in only confirmed by biopsy and histology
Ultra-low-dose CT with model-based iterative reconstruction (MBIR): detection of ground-glass nodules in an anthropomorphic phantom study
No full textPurpose: The authors sought to evaluate the effect of model-based iterative reconstruction (MBIR) on the sensitivity of ground-glass nodule (GGN) detection at different dose levels.Materials and methods: Fifty-four artificial GGN were randomly divided into three sets, each positioned in an anthropomorphic phantom. The three sets were evaluated on standard-dose (SD, 350 mA), low-dose (LD, 35 mA) and ultra-low-dose (ULD, 10 mA) CT scans (100 kV, 64 × 0.625 mm, 0.5 s), and each scan was reconstructed twice with filtered back projection (FBP) and MBIR. Three radiologists independently evaluated the scans for GGN presence and size. SD + FBP was considered the reference standard. A region of interest (ROI) was used to calculate signal-to-noise ratio (SNR) and contrast-to-noise ratio normalised to dose (CNRD). McNemar’s test, Bland–Altman analysis and t test were used for statistical assessment (p 0.05). Bland–Altman analysis showed a good reader agreement (±1.5 mm) for GGN size between SD + FBP and ULD + MBIR. For low dose and ultra-low dose, the SNR and CNRD were significantly higher with MBIR (p < 0.0001). The effective dose was 97.1 % lower with ultra-low dose (0.15 mSv) than standard dose (5.15 mSv).Conclusions: The detection of GGN with MBIR at low-dose and ultra-low-dose CT does not differ significantly from standard-dose CT with FBP in an anthropomorphic phantom
Swallowing Disorders after Oral Cavity and Pharyngolaryngeal Surgery and Role of Imaging
Full text linkHead and neck squamous cell carcinoma is the sixth most common cancer diagnosed worldwide and the eighth most common cause of cancer death. Malignant tumors of the oral cavity, oropharynx, and larynx can be treated by surgical resection or radiotheraphy with or without chemotheraphy and have a profound impact on quality of life functions, including swallowing. When surgery is the chosen treatment modality, the patient may experience swallowing impairment in the oral and pharyngeal phases of deglutition. A videofluoroscopic study of swallow enables the morphodynamics of the pharyngeal-esophageal tract to be accurately examined in patients with prior surgery. These features allow an accurate tracking of the various phases of swallowing in real time, identifying the presence of functional disorders and of complications during the short- and long-term postoperative recovery. The role of imaging is fundamental for the therapist to plan rehabilitation. In this paper, the authors aim to describe the videofluoroscopic study of swallow protocol and related swallowing impairment findings in consideration of different types of surgery
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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