11 research outputs found

    Characterizing the Sardinia candidate site for the Einstein Telescope

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    Due to its unique geophysical features and to the low density population of the area, Sos Enattos is a promising candidate site to host the Einstein Telescope (ET), the third-generation Gravitational Wave Observatory. The geophysical characterization of the Sos Enattos former mine, close to one of the proposed ET corners, started in 2010 with the deployment of seismic and environmental sensors underground. Since 2019 a new extensive array of seismometers, magnetometers and acoustic sensors have been installed in three stations along the underground tunnels, with one additional station at the surface. Beside a new geological survey over a wider area, two boreholes about 270 m deep each were excavated at the other two corners, determining the good quality of the drilled granite and orthogneiss rocks and the absence of significant thoroughgoing fault zones. These boreholes are instrumented with broadband seismometers that revealed an outstanding low level of vibrational noise in the low-frequency band of ET-LF (2-10Hz), significantly lower than the Peterson's NLNM and resulting among the quietest seismic stations in the world in that frequency band. The low seismic background and the reduced number of seismic glitches ensure that just a moderated Newtonian noise subtraction would be needed to achieve the ET target sensitivity. Geoelectrical and active seismic campaigns have been carried out to reveal the features of the subsurface, revealing the presence of small-sized fractured areas with limited water circulation. Finally, temporary arrays of seismometers, magnetometers and acoustic sensors are deployed in the area to study the local sources of environmental noise

    Kernel convergence theorems and Graph Neural Networks in the infinite width limit

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    In questo lavoro vengono analizzati aspetti riguardanti Neural Networks (NNs) e Graph Neural Networks (GNNs) di ampiezza infinita. Questo studio è motivato da alcuni risultati che stabiliscono l'equivalenza tra processi Gaussiani e reti neurali completamente connesse di ampiezza infinita all'inizializzazione. Quindi, si può utilizzare la funzione di covarianza del processo Gaussiano corrispondente a una rete neurale infinitamente ampia per fare previsioni e inferenza. Dunque, questo fatto collega la teoria delle reti neurali ai metodi kernel. Durante il training di una rete neurale, la funzione output segue un'equazione differenziale ordinaria finito-dimensionale scritta in termini di un nuovo nucleo: il Neural Tangent Kernel (NTK). Viene quindi studiata la convergenza del NTK, in particolare si dimostra che, per un'opportuna scelta dei parametri all'inizializzazione, il Neural Tangent Kernel converge in probabilità ad un nucleo deterministico quando l'ampiezza dei layer nascosti tende ad infinito sequenzialmente. Il risultato di convergenza vale sia all'inizializzazione sia durante il training. Come conseguenza, nel caso di ampiezza infinita, la funzione output varia durante il training seguendo un'equazione differenziale in cui compare il nucleo limite. Inoltre, il nucleo limite soddisfa una relazione per ricorrenza in cui è coinvolta la funzione di covarianza del processo Gaussiano corrispondente a una rete neurale infinitamente ampia. Nel lavoro di tesi si studia il comportamento della funzione output anche nel caso di una Graph Neural Network. Si può costruire una GNN tramite operazioni di somma sui vicini e aggiornamento dei feature vectors associati a ogni nodo; quest'ultima si realizza con una rete neurale completamente connessa. In questo lavoro si dimostra che anche nel caso di una GNN, all'inizializzazione, la funzione output converge in legge ad un processo Gaussiano quando l'ampiezza dei layer intermedi tende ad infinito sequenzialmente. Si può quindi definire un analogo del nucleo limite del NTK anche nel contesto delle Graph Neural Networks, collegando in questo caso la teoria delle Graph Neural Networks ai metodi kernel

    Path Tracing vs. Volume Rendering Technique in Post-Surgical Assessment of Bone Flap in Oncologic Head and Neck Reconstructive Surgery: A Preliminary Study

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    : This study aims to compare a relatively novel three-dimensional rendering called Path Tracing (PT) to the Volume Rendering technique (VR) in the post-surgical assessment of head and neck oncologic surgery followed by bone flap reconstruction. This retrospective study included 39 oncologic patients who underwent head and neck surgery with free bone flap reconstructions. All exams were acquired using a 64 Multi-Detector CT (MDCT). PT and VR images were created on a dedicated workstation. Five readers, with different expertise in bone flap reconstructive surgery, independently reviewed the images (two radiologists, one head and neck surgeon and two otorhinolaryngologists, respectively). Every observer evaluated the images according to a 5-point Likert scale. The parameters assessed were image quality, anatomical accuracy, bone flap evaluation, and metal artefact. Mean and median values for all the parameters across the observer were calculated. The scores of both reconstruction methods were compared using a Wilcoxon matched-pairs signed rank test. Inter-reader agreement was calculated using Spearman's rank correlation coefficient. PT was considered significantly superior to VR 3D reconstructions by all readers (p < 0.05). Inter-reader agreement was moderate to strong across four out of five readers. The agreement was stronger with PT images compared to VR images. In conclusion, PT reconstructions are significantly better than VR ones. Although they did not modify patient outcomes, they may improve the post-surgical evaluation of bone-free flap reconstructions following major head and neck surgery

    Randomized Controlled Trial of Botulinum Toxin Versus Laparoscopic Heller Myotomy for Esophageal Achalasia

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    OBJECTIVE: To compare laparoscopic cardia myotomy and fundoplication with botulinum toxin (BoTx) injection in patients with esophageal achalasia. SUMMARY BACKGROUND DATA: Although myotomy is thought to offer better results, recent studies have reported 80% success rates after 2 BoTx injections a month apart. No randomized controlled trials comparing the 2 treatments have been published so far. MATERIALS AND METHODS: Newly diagnosed achalasia patients were randomly assigned to BoTx injection or laparoscopic myotomy. Symptoms were scored; lower esophageal sphincter resting and nadir pressures were measured by manometry; barium swallow was used to assess esophageal diameter pre- and post-treatment. Eight to one hundred units of BoTx were injected twice, a month apart, at the esophagogastric junction. Myotomy included anterior partial (Dor) or Nissen fundoplication. RESULTS: Eighty patients were involved in the study: 40 received BoTx and 40 underwent myotomy. Mortality was nil. One surgical patient bled from the trocar site. Median hospital stay was 6 days for surgery; BoTox patients were treated as day-hospital admissions. All patients completed the follow-up. After 6 months, the results in the 2 groups were comparable, although symptom scores improved more in surgical patients (82% confidence interval [CI] 76–89 vs. 66% CI 57–75, P < 0.05). The drop in lower esophageal sphincter pressure was similar in the 2 groups; the reduction in esophageal diameter was greater after surgery (19% CI 13–26 vs. 5% CI 2–11, P < 0.05). Later on, symptoms recurred in 65% of the BoTx-treated patients and the probability of being symptom-free at 2 years was 87.5% after surgery and 34% after BoTx (P < 0.05). CONCLUSION: Laparoscopic myotomy is as safe as BoTx treatment and is a 1-shot treatment that cures achalasia in most patients. BoTx should be reserved for patients who are unfit for surgery or as a bridge to more effective therapies, such as surgery or endoscopic dilation

    Magnetic Resonance Imaging Evaluation of Bone Metastases Treated with Radiotherapy in Palliative Intent: A Multicenter Prospective Study on Clinical and Instrumental Evaluation Assessment Concordance (MARTE Study)

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    Metastasis to bone is a common occurrence among epithelial tumors, with a high incidence rate in the Western world. As a result, bone lesions are a significant burden on the healthcare system, with a high morbidity index. These injuries are often symptomatic and can lead to functional limitations, which in turn cause reduced mobility in patients. Additionally, they can lead to secondary complications such as pathological fractures, spinal cord compression, hypercalcemia, or bone marrow suppression. The treatment of bone metastases requires collaboration between multiple healthcare professionals, including oncologists, orthopedists, neurosurgeons, physiatrists, and radiotherapists. The primary objective of this study is to evaluate the correlation between two methods used to assess local control. Specifically, the study aims to determine if a reduction in the volume of bone lesions corresponds to better symptomatic control in the clinical management of patients, and vice versa. To achieve this objective, the study evaluates morphological criteria by comparing pre- and post-radiotherapy treatment imaging using MRI and RECIST 1.1 criteria. MRI without contrast is the preferred diagnostic imaging method, due to its excellent tolerance by patients, the absence of exposure to ionizing radiation, and the avoidance of paramagnetic contrast media side effects. This imaging modality allows for accurate assessment of bone lesions. One of the secondary objectives of this study is to identify potentially useful parameters that can distinguish patients into two classes: "good" and "poor" responders to treatment, as reported by previous studies in the literature. These parameters can be evaluated from the imaging examinations by analyzing morphological changes and radiomic features on different sequences, such as T1, STIR (short tau inversion recovery), and DWI-MRI (diffusion-weighted)

    Structured Reporting of Computed Tomography and Magnetic Resonance in the Staging of Pancreatic Adenocarcinoma: A Delphi Consensus Proposal

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    Background: Structured reporting (SR) in radiology has been recognized recently by major scientific societies. This study aims to build structured computed tomography (CT) and magnetic resonance (MR)-based reports in pancreatic adenocarcinoma during the staging phase in order to improve communication between the radiologist and members of multidisciplinary teams. Materials and methods: A panel of expert radiologists, members of the Italian Society of Medical and Interventional Radiology, was established. A modified Delphi process was used to develop the CT-SR and MRI-SR, assessing a level of agreement for all report sections. Cronbach's alpha (Cα) correlation coefficient was used to assess internal consistency for each section and to measure quality analysis according to the average inter-item correlation. Results: The final CT-SR version was built by including n = 16 items in the "Patient Clinical Data" section, n = 11 items in the "Clinical Evaluation" section, n = 7 items in the "Imaging Protocol" section, and n = 18 items in the "Report" section. Overall, 52 items were included in the final version of the CT-SR. The final MRI-SR version was built by including n = 16 items in the "Patient Clinical Data" section, n = 11 items in the "Clinical Evaluation" section, n = 8 items in the "Imaging Protocol" section, and n = 14 items in the "Report" section. Overall, 49 items were included in the final version of the MRI-SR. In the first round for CT-SR, all sections received more than a good rating. The overall mean score of the experts was 4.85. The Cα correlation coefficient was 0.85. In the second round, the overall mean score of the experts was 4.87, and the Cα correlation coefficient was 0.94. In the first round, for MRI-SR, all sections received more than a good rating. The overall mean score of the experts was 4.73. The Cα correlation coefficient was 0.82. In the second round, the overall mean score of the experts was 4.91, and the Cα correlation coefficient was 0.93. Conclusions: The CT-SR and MRI-SR are based on a multi-round consensus-building Delphi exercise derived from the multidisciplinary agreement of expert radiologists in order to obtain more appropriate communication tools for referring physicians

    Bloating is associated with worse quality of life, treatment satisfaction, and treatment responsiveness among patients with constipation-predominant irritable bowel syndrome and functional constipation

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    Background: The management of bloating is unclear and its relationship with patients' well-being and treatment satisfaction independent of other abdominal symptoms is uncharacterized. We evaluated the association of bloating with patient-reported outcomes. Methods: Thirty-nine centers for functional gastrointestinal disorders joined the laxative inadequate relief survey. We enrolled 2203 consecutive outpatients with functional constipation (FC) or constipation-predominant irritable bowel syndrome (IBS-C) in two cross-sectional waves. Both wave 1 and 2 included the SF-12, the patient assessment of constipation-symptoms (PAC-SYM), and the treatment satisfaction questionnaire for medication (TSQM-2). Wave 2 only included a global rating of change (GRC) scale to assess patients' assessment of efficacy concerning treatment switches occurred in the 3 months prior to the interview. Bloating in the abdomen was defined on the basis of PAC-SYM item 3. Key Results: The average age was 50.1 years (SD, 16.7) and 82.1% of patients were women. The prevalence of bloating was 91.6% (n = 1970). Bloating was associated with SF-12 Physical Composite Score (p &lt; 0.01), SF-12 Mental Composite Score (p &lt; 0.01), GRC (p &lt; 0.01), Satisfaction with treatment effectiveness (p &lt; 0.01), convenience of administration (p &lt; 0.01), and side effects (p &lt; 0.01) after adjustment for possible confounders. Conclusions &amp; Inferences: Our data suggest that patients regard bloating as a key element in assessing clinical changes and treatments' efficacy as this symptom exerts a strong influence on patient-reported outcomes independent of possible confounders and other symptoms of constipation. Our data provide the rationale to investigate the efficacy and tolerability of new treatments specifically addressing this important, yet disregarded, patients' complain
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