Distilling the topology of the Hofstadter model through a diffraction experiment

In two and three spatial dimensions, the transverse response experienced by a charged particle on a lattice in a uniform magnetic field is proportional to a topological invariant, the first Chern number, characterizing the energy bands of the underlying Hofstadter Hamiltonian. In four dimensions, the transverse response is also quantized, and controlled by the second Chern number. These remarkable features solely arise from the magnetic translational symmetry. Here we show that the symmetries of the two-, three- and four-dimensional Hofstadter Hamiltonians may be encrypted in optical diffraction gratings, such that simple photonic experiments allow one to extract the first and the second Chern numbers of the whole energy spectra. This result is particularly remarkable in three and four dimensions, where complete topological characterizations have not yet been achieved experimentally. Side-by-side to the theoretical analysis, in this work we present the experimental study of optical gratings analogues of the two- and three-dimensional Hofstadter models

Protective intraoperative ventilation with higher versus lower levels of positive end-expiratory pressure in obese patients (PROBESE): study protocol for a randomized controlled trial

Background: Postoperative pulmonary complications (PPCs) increase the morbidity and mortality of surgery in obese patients. High levels of positive end-expiratory pressure (PEEP) with lung recruitment maneuvers may improve intraoperative respiratory function, but they can also compromise hemodynamics, and the effects on PPCs are uncertain. We hypothesized that intraoperative mechanical ventilation using high PEEP with periodic recruitment maneuvers, as compared with low PEEP without recruitment maneuvers, prevents PPCs in obese patients. Methods/design The PRotective Ventilation with Higher versus Lower PEEP during General Anesthesia for Surgery in OBESE Patients (PROBESE) study is a multicenter, two-arm, international randomized controlled trial. In total, 2013 obese patients with body mass index ≥35 kg/m2 scheduled for at least 2 h of surgery under general anesthesia and at intermediate to high risk for PPCs will be included. Patients are ventilated intraoperatively with a low tidal volume of 7 ml/kg (predicted body weight) and randomly assigned to PEEP of 12 cmH2O with lung recruitment maneuvers (high PEEP) or PEEP of 4 cmH2O without recruitment maneuvers (low PEEP). The occurrence of PPCs will be recorded as collapsed composite of single adverse pulmonary events and represents the primary endpoint. Discussion To our knowledge, the PROBESE trial is the first multicenter, international randomized controlled trial to compare the effects of two different levels of intraoperative PEEP during protective low tidal volume ventilation on PPCs in obese patients. The results of the PROBESE trial will support anesthesiologists in their decision to choose a certain PEEP level during general anesthesia for surgery in obese patients in an attempt to prevent PPCs. Trial registration ClinicalTrials.gov identifier: NCT02148692. Registered on 23 May 2014; last updated 7 June 2016. Electronic supplementary material The online version of this article (doi:10.1186/s13063-017-1929-0) contains supplementary material, which is available to authorized users

Statistical classification for assessing PRISMA hyperspectral potential for agricultural land use

The upcoming launch of the next generation of hyperspectral satellites (PRISMA, EnMap, HyspIRI, etc.) will meet the increasing demand for the availability/accessibility of hyperspectral information on agricultural land use from the agriculture community. To this purpose, algorithms for the classification of remotely sensed images are here considered for agricultural monitoring of cultivated area, exploiting remotely sensed high spectral resolution images. Classification is accomplished by procedures based on discriminant analysis tools that well suit hyperspectrality, circumventing what in statistics is called “the curse of dimensionality”. As a byproduct of classification, a full assessment of the spectral bands of the sensor is obtained, ranking them with the purpose of understanding their role in segmentation and classification. The methodology has been validated on two independent image datasets gathered by the MIVIS (Multispectral Infrared and Visible Imaging Spectrometer) sensor for which ground validations were available. A comparison with the popular multiclass SVM (Support Vector Machines) classifier is also presented. Results show that a good classification (minimum global success rate 95% through all experiments) is achieved by using the 10 spectral bands selected as the most discriminant by the proposed procedure; moreover, it also appears that nonparametric techniques generally outperform parametric ones. The present study confirms that the new generation of hyperspectral satellite data like PRISMA can ripen an end-user application for agricultural land-use of cultivated area

A new simple score for prediction of difficult laryngoscopy: the EL.GA+ score

Preoperative airway assessment plays a key role in the context of difficult airway management. Several scores have been proposed to predict difficult intubation including the el-Ganzouri index (EL.GA). Anatomical parameters such as the opening of the mouth or the circumference of the neck (which currently is not usually evaluated) are used to predict difficult intubation. The nutritional status of super-morbid obesity (body mass index [BMI] > 50 kg m-2) is a recognised risk factor for difficult intubation

Lymphopenia in patients affected by SARS-CoV-2 infection is caused by margination of lymphocytes in large bowel: an [18F]FDG PET/CT study

Background To investigate the cause of lymphopenia in patients with newly diagnosed COVID-19, we measured [18F]FDG uptake in several tissues, including the ileum, right colon, and caecum at diagnosis and after recovery and correlated these measurements with haematological parameters. Methods We studied, by [18F]FDG PET/CT, 18 newly diagnosed patients with COVID-19. Regions of interest were drawn over major organs and in the terminal ileum, caecum, and right colon, where the bowel wall was evaluable. Five patients were re-examined after recovery, and three of them also performed a white blood cell scan with 99mTc-HMPAO-WBC on both occasions. Complete blood count was performed on both occasions, and peripheral blood lymphocyte subsets were measured at diagnosis. Data were analysed by a statistician. Results Patients had moderate severity COVID-19 syndrome. Basal [18F]FDG PET/CT showed focal lung uptake corresponding to hyperdense areas at CT. We also found high spleen, ileal, caecal, and colonic activity as compared to 18 control subjects. At recovery, hypermetabolic tissues tended to normalize, but activity in the caecum remained higher than in controls. Regression analyses showed an inverse correlation between CD4 + lymphocytes and [18F]FDG uptake in the caecum and colon and a direct correlation between CD8 + lymphocytes and [18F]FDG uptake in lungs and bone marrow. WBC scans showed the presence of leukocytes in the caecum and colon that disappeared at recovery. Conclusions These findings indicate that lymphopenia in COVID-19 patients is associated with large bowel inflammation supporting the hypothesis that CD4 + lymphocytes migrate to peripheral lymphoid tissues in the bowel

Autonomous functioning thyroid nodules and 131I in diagnosis and therapy after 50 years of experience: What is still open to debate?

PURPOSE OF THE REPORT: Autonomous functioning thyroid nodules (AFTN), defined as "hot nodules" at thyroid scan, are often cured by radioiodine treatment. The aim of our study was to investigate the long-term outcome in patients treated with an I calculated dose, to identify a possible "size-tailored" dose, and to simplify follow-up procedures. PATIENTS AND METHODS: Retrospective analysis was carried out on 1402 cases, covering a period of 50 years, of AFTN treated with an I calculated dose. Our study focused on nodular size and mean administered dose. Concordance between thyroid scan and serum TSH levels at 3-6 months from treatment was considered. RESULTS: A single I dose was effective for the vast majority of patients (93%). The outcome was influenced by nodular size. On the basis of the Italian dose limit for outpatient treatment, our population was divided into subgroups according to administered doses (more or less than 16 mCi) and nodular dimensions: no differences in outcome were observed for each class of nodule size. A dose ≤10 mCi was effective on the smaller nodules (50.1% of our population). The agreement between TSH and scan after treatment was 90.3% at 3 months and 94.5% at 6 months. CONCLUSIONS: I therapy with a calculated dose is an effective treatment of AFTN. If a fixed dose is chosen, 16 mCi is often resolutive and for nodules 5 cm are eligible for surgery. TSH is the only parameter required to evaluate the outcome. © 2013 by Lippincott Williams & Wilkins

Long-term results of PRRT in advanced bronchopulmonary carcinoid

Purpose: Peptide receptor radionuclide therapy (PRRT) for the treatment of neuroendocrine tumours (NET) has been explored for almost two decades, but there are still few trials that have exclusively investigated well-differentiated and moderately differentiated NET arising from the respiratory tree. Thus, the aim of this study was to explore the outcome in patients affected by bronchopulmonary carcinoid (BPC) following PRRT. Methods: We retrospectively analysed 114 patients with advanced stage BPC consecutively treated with PRRT at the European Institute of Oncology, Milan, from 1997 to 2012 and followed until October 2014. The objective responses, overall survival (OS) and progression-free survival (PFS) were rated, and three different PRRT protocols (90Y-DOTATOC vs. 177Lu-DOTATATE vs. 90Y-DOTATOC + 177Lu-DOTATATE) were compared with regard to their efficacy and tolerability. Results: The median OS (evaluated in 94 of the 114 patients) was 58.8 months. The median PFS was 28.0 months. The 177Lu-DOTATATE protocol resulted in the highest 5-year OS (61.4 %). Morphological responses (partial responses + minor responses) were obtained in 26.5 % of the cohort and were associated with longer OS and PFS. The 90Y-DOTATOC + 177Lu-DOTATATE protocol provided the highest response rate (38.1 %). Adverse events were mild in the majority of patients. However, haematological toxicity negatively affected survival. No severe (grade 3/4) serum creatinine increase was observed. Patients treated with 90Y-DOTATOC alone more frequently showed a mild/moderate decrease in renal function. In patients treated with chemotherapy before PRRT had a shorter OS and PFS, and a higher risk of developing nephrotoxicity. Conclusion: In a large cohort of patients with advanced BPC treated in a â\u80\u9creal-worldâ\u80\u9d scenario and followed up for a median of 45.1 months (range 2 â\u80\u93 191 months), PRRT proved to be promising in prolonging survival and delaying disease progression. Despite the potential selection biases, considering the risk-benefit ratio, 177Lu-DOTATATE monotherapy seems the best option for PRRT. Our results indicate that the use of PRRT in earlier stages of the disease could provide a more favorable outcome

A Retrospective Analysis of the Correlation between Functional Imaging and Clinical Outcomes in Grade 3 Neuroendocrine Tumors (NETs G3)

Grade 3 (G3) neuroendocrine tumors (NETs) are a novel category among digestive neuroendocrine neoplasms, characterized by Ki-67 >20% and a well-differentiated morphology, presenting high intra-tumor heterogeneity. We aimed to explore the role of dual-tracer PET imaging (68Gallium (Ga)-DOTATOC and 18Fluorodeoxyglucose (FDG)) as overall survival (OS) predictor in NET G3 patients. We performed a retrospective analysis in NET G3 patients treated at our institution between 2003 and 2021. Accordingly, 30 NET G3 patients were analyzed. 68Ga-DOTA-TOC and 18F-FDG uptake were assessed by tumor/non-tumor (T-nonT) ratio. We reported a slightly better OS for patients with ≥75% concordance between 68Ga-DOTA-TOC and 18F-FDG PET/CT (p = 0.42). Among patients with discordant functional imaging, we reported a better 5-y OS rate for patients with a prevalent 68Ga-DOTATOC vs. 18F-FDG PET/CT (p = 0.016). In positive 18F-FDG PET/CT cases, we reported a better OS for <4 vs. ≥4 T/non-T ratio (p = 0.021). Among upfront-NET G3 patients with concordant exams, 5-y OS rate was 83.3% (95% CI: 27.3–97.5). Among patients with discordant exams, 5-y OS rate was 81.3% (52.5–93.5), 100% for those with prevalent receptor expression, and 50% (11.1–80.4) for those with prevalent 18F-FDG uptake. Our findings suggest that dual-tracer PET/CT can be considered as a predictor of patient outcome, able to stratify NET G3 patients with poorer prognosis