852 research outputs found
Birkhoff Normal Form and Long Time Existence for Periodic Gravity Water Waves
We consider the gravity water waves system with a periodic one-dimensional interface in infinite depth and give a rigorous proof of a conjecture of Dyachenko-Zakharov [16] concerning the approximate integrability of these equations. More precisely, we prove a rigorous reduction of the water waves equations to its integrable Birkhoff normal form up to order 4. As a consequence, we also obtain a long-time stability result: periodic perturbations of a flat interface that are initially of size Δ remain regular and small up to times of order (Formula presented.). This time scale is expected to be optimal. © 2022 The Authors. Communications on Pure and Applied Mathematics published by Wiley Periodicals LLC
Recommended from our members
The application of Rapid Appraisal of Agricultural Innovation Systems (RAAIS) to agricultural adaptation to climate change in Kazakhstan: a critical evaluation
Place-based social, cultural, institutional and political dynamics not only influence the innovation capacity of agricultural systems, but also the willingness of relevant actors to be involved in participatory research processes, and the dynamics of their participation. This paper critically discusses the modification and application of one particular participatory approach to agricultural systems analysis (Rapid Appraisal of Agricultural Innovation Systems [RAAIS]) to agricultural adaptation in Southeast Kazakhstan. We consider the overall effectiveness of the method as a research tool, practical issues in the implementation of workshops, definition of and selection of participant groups, as well as the questions of participation and empowerment within the workshops themselves. We find that although RAAIS is adaptable to alternative theoretical frameworks, its implementation in different socio-cultural and political contexts may require more consideration than is apparent in previous discussions. In particular, the appropriate training of workshop organisers is of crucial importance to the success of this methodology. These findings will be useful to those adapting participatory research methods to different research topics and contexts more broadly
Intrapancreatic accessory spleen false positive to 68Ga-Dotatoc: case report and literature review
Background: Intrapancreatic accessory spleen (IPAS) is an uncommon finding of pancreatic mass. Differential diagnosis with pancreatic tumor, especially with non-functional neuroendocrine tumor (NF-NET), may be very hard and sometimes it entails unnecessary surgery. A combination of CT scan, MRI, and nuclear medicine can confirm the diagnosis of IPAS. 68-Ga-Dotatoc PET/CT is the gold standard in NET diagnosis and it can allow to distinguish between IPAS and NET. Case presentation: A 69-year-old man was admitted to our hospital for an incidental nodule in the tail of the pancreas with focal uptake of 68-Ga-dotatate at PET/CT. NET was suspected and open distal splenopancreatectomy was performed. Pathologic examination revealed an IPAS. Conclusion: This is the second IPAS case in which a positive 68Ga-Dotatoc uptake led to a false diagnosis of pancreatic NET. Here is a proposal of a literature review
Recommended from our members
LiDAR mapping of tidal marshes for ecogeomorphological modelling in the TIDE project
The European research project TIDE (Tidal Inlets Dynamics and Environment) is developing and validating coupled models describing the morphological, biological and ecological evolution of tidal environments. The interactions between the physical and biological processes occurring in these regions requires that the system be studied as a whole rather than as separate parts. Extensive use of remote sensing including LiDAR is being made to provide validation data for the modelling.
This paper describes the different uses of LiDAR within the project and their relevance to the TIDE science objectives. LiDAR data have been acquired from three different environments, the Venice Lagoon in Italy, Morecambe Bay in England, and the Eden estuary in Scotland. LiDAR accuracy at each site has been evaluated using ground reference data acquired with differential GPS. A semi-automatic technique has been developed to extract tidal channel networks from LiDAR data either used alone or fused with aerial photography. While the resulting networks may require some correction, the procedure does allow network extraction over large areas using objective criteria and reduces fieldwork requirements. The networks extracted may subsequently be used in geomorphological analyses, for example to describe the drainage patterns induced by networks and to examine the rate of change of networks. Estimation of the heights of the low and sparse vegetation on marshes is being investigated by analysis of the statistical distribution of the measured LiDAR heights. Species having different mean heights may be separated using the first-order moments of the height distribution
Natural History and Management of Familial Paraganglioma Syndrome Type 1: Long-Term Data from a Large Family
Head and neck paragangliomas are the most common clinical features of familial paraganglioma syndrome type 1 caused by succinate dehydrogenase complex subunit D (SDHD) mutation. The clinical management of this syndrome is still unclear. In this study we propose a diagnostic algorithm for SDHD mutation carriers based on our family case series and literature review. After genetic diagnosis, first evaluation should include biochemical examination and whole-body imaging. In case of lesion detection, nuclear medicine examination is required for staging and tumor characterization. The study summarizes the diagnostic accuracy of different functional imaging techniques in SDHD mutation carriers. 18F-3,4-dihydroxyphenylalanine (18F-DOPA) positron emission tomography (PET)-computed tomography (CT) is considered the gold standard. If it is not available, 123I-Metaiodobenzylguanidine (MIBG) could be used also for predicting response to radiometabolic therapy. 18F-fluoro-2-deoxy-D-glucose (18F-FDG) PET-CT has a prognostic role since high uptake identifies more aggressive cases. Finally, 68Ga-peptides PET-CT is a promising diagnostic technique, demonstrating the best diagnostic accuracy in our and in other published case series, even if this finding still needs to be confirmed in larger studies. Periodic follow-up should consist of annual biochemical and ultrasonographic screening and biannual magnetic resonance examination to identify biochemical silent tumors early
First surveillance of violence against women during covid-19 lockdown: Experience from âniguardaâ hospital in milan, italy
Violence against women emerges with tragic regularity in the daily news. It is now an evident trace of a dramatic social problem, the characteristics of which are not attributable to certain economic, cultural, or religious conditions of the people involved but affect indiscriminately, in a unanimous way, our society. The study is a survey about the number of hospital admissions due to episodes attributable to violence against women, recorded by the Niguarda Hospital in Milan in the period 1 Marchâ30 May from 2017 to 2020. This period, in 2020, corresponds to the coronavirus Lockdown in Italy. All the medical records of the Emergency department were reviewed, and the extracted data classified in order to identify the episodes of violence against women and the features of the reported injuries and the characteristics of the victims. The data did not show an increase in the number of cases in 2020 compared to previous years, but we did find a notable increase in the severity of injuries
The effects of reduced physical activity on the lipid profile in patients with high cardiovascular risk during covid-19 lockdown
Background: The COVID-19 pandemic is a serious global health problem. In Italy, to limit the infections, the government ordered lockdown from March 2020. This measure, designed to contain the virus, led to serious limitations on the daily life of the individuals it affected, and in particular in the limitation of physical exercise. The aim of this study was to evaluate the effects of reduced physical activity on the lipid profile in patients with high cardiovascular risk. Methods: We enrolled 38 dyslipidemic patients, 56% male, with an age range of 44â62 years, considered to be at high cardiovascular risk. All patients were prescribed statin drug therapy (atorvastatin 40 mg) and a vigorous physical activity program four times a week, 1 h per session. In addition, a personalized Mediterranean diet was prescribed to all the patients. Total cholesterol, LDL, HDL and triglycerides were measured in patients at T0 before lockdown and at T1 during lockdown. Results: Data showed a significant increase (p < 0.01) in total cholesterol (+6,8%) and LDL (+15,8%). Furthermore, the analysis of the data revealed a reduction in HDL (â3%) and an increase in triglycerides (+3,2%), although both were not significant (p > 0.05). Conclusions: Our study showed that the reduction in physical activity during lockdown led to an increase in LDL levels, and therefore, in the risk of ischemic heart disease in dyslipidemic patients with high cardiovascular risk
- âŠ