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The divergence of nearby trajectories in soft-sphere DEM

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Particuology 2022年第4期20卷 1-8页

作者： William D.Fullmer Roberto porcu Jordan Musser Ann S.Almgren Ishan Srivastava National Energy Technology Laboratory MorgantownWV 26507USA NETL Support Contractor MorgantownWV 26507USA Center for Computational Sciences and Engineering.Lawrence Berkeley National Laboratory BerkeleyCA 94720USA

The n-body instability is investigated with the soft-sphere discrete element *** divergence of nearby trajectories is quantifed by the dynamical memory *** the inverse proportionality between the dynamical memory time and the largest Lyapunov exponent,the soft-sphere discrete ele-ment method results are compared to previous hard-sphere molecular dynamics data for the first *** agreement is observed at low concentrations and the degree of instability is shown to increase asymptotically with increasing spring *** particle concentrations above 30%,the soft-sphere Lya-punov exponents increase faster than the corresponding hard-sphere *** paper concludes with a demonstration of how this case study may be used in conjunction with regression testing and code verification activities.

关键词： Soft-sphere DEM Chaos Lyapunov exponent

Retroaortic left renal vein associated to variations of liver vasculature and biliary system in a patient submitted to total pancreatectomy

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Hepatobiliary & Pancreatic Diseases International 2024年第5期23卷 526-529页

作者： Alessandro Fancellu Mario Maiore Lavinia Grasso Miriam Ferrara Alberto porcu Department of Medicine Surgery and PharmacyUnit of General Surgery 2-Clinica ChirurgicaUniversity of SassariSassari 07100Italy Department of Medicine Surgery and PharmacyUnit of RadiologyUniversity of SassariSassari 07100Italy

Total pancreatectomy(TP) is a surgical procedure which includes the complete removal of the pancreatic gland, the spleen, the duodenum, the gallbladder, and the distal part of the stomach. TP represents the curative treatment of pancreatic cancer which simultaneously involves the head and the body/tail of the pancreas. Other possible indications for TP comprise multifocal parenchymal diseases, such as intraductal papillary mucinous neoplasms, pancreatic neuroendocrine tumors, multiple endocrine neoplasms, and chronic pancreatitis. Sometimes, TP is carried out in patients scheduled for pancreaticoduodenectomy(where only the head of the pancreas is removed) when a cancer located in the pancreatic head is intraoperatively found to also extend to the pancreatic body [1].

关键词： neoplasms stomach spleen

Current role of hepatopancreatoduodenectomy for the management of gallbladder cancer and extrahepatic cholangiocarcinoma:A systematic review

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World Journal of Gastrointestinal Oncology 2021年第6期13卷 625-637页

作者： Alessandro Fancellu Valeria Sanna Giulia Deiana Chiara Ninniri Davide Turilli Teresa Perra Alberto porcu Department of Medical Surgical and Experimental SciencesUniversity of SassariSassari 07100Italy Unit of Oncology AOU SassariSassari 07100Italy Unit of Radiology AOU SassariSassari 07100Italy

BACKGROUND Hepatopancreatoduodenectomy(HPD)is the simultaneous combination of hepatic resection,pancreaticoduodenectomy,and resection of the entire extrahepatic biliary *** is not a universally accepted due to high mortality and morbidity rates,as well as to controversial survival *** To evaluate the current role of HPD for curative treatment of gallbladder cancer(GC)or extrahepatic cholangiocarcinoma(ECC)invading both the hepatic hilum and the intrapancreatic common bile *** A systematic literature search using the PubMed,Web of Science,and Scopus databases was performed to identify studies reporting on HPD,using the following keywords:‘Hepatopancreaticoduodenectomy’,‘hepatopancreatoduodenectomy’,‘hepatopancreatectomy’,‘pancreaticoduodenectomy’,‘hepatectomy’,‘hepatic resection’,‘liver resection’,‘Whipple procedure’,‘bile duct cancer’,‘gallbladder cancer’,and‘cholangiocarcinoma’.RESULTS This updated systematic review,focusing on 13 papers published between 2015 and 2020,found that rates of morbidity for HPD have remained high,ranging between 37.0%and 97.4%,while liver failure and pancreatic fistula are the most serious ***,perioperative mortality for HPD has decreased compared to initial experiences,and varies between 0%and 26%,although in selected center it is well below 10%.Long term survival outcomes can be achieved in selected patients with R0 resection,although 5–year survival is better for ECC than *** The present review supports the role of HPD in patients with GC and ECC with horizontal spread involving the hepatic hilum and the intrapancreatic bile duct,provided that it is performed in centers with high experience in hepatobiliarypancreatic *** use of preoperative portal vein embolization,and preoperative biliary drainage in patients with obstructive jaundice,represent strategies for decreasing the occurrence and severity of postoperative *** is advisable to develop internationa

关键词： Hepatopancreatoduodenectomy Extrahepatic cholangiocarcinoma Gallbladder cancer Survival Morbidity Mortality

Hepatopancreatoduodenectomy for the treatment of extrahepatic cholangiocarcinoma

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Hepatobiliary & Pancreatic Diseases International 2023年第4期22卷 430-433页

作者： Alberto porcu Giulia Deiana Claudio F Feo Chiara Ninniri Davide Turilli Lorena Tanda Alessandro Fancellu Department of Clinical Surgical and Experimental SciencesUnit of General Surgery 2–Clinica ChirurgicaUniversity of SassariSassariItaly Unit of Radiological Sciences AOU SassariSassariItaly Faculty of Medicine and Surgery University of SassariSassariItaly

To the Editor:Extrahepatic cholangiocarcinoma(ECC)is an uncommon neoplasm associated with a poor prognosis[1-3].Surgical resection represents the only curative approach,since systemic treatments have scarce efficacy in achieving disease ***,only 10%-40%of patients with ECC are resectable at diagnosis[1].Ma-jor hepatectomy and portal lymphadenectomy are usually required for hilar ECC,while pancreatoduodenectomy is the standard operation for distal ECC[3-5].However,ECC may spread horizon-tally along the biliary tree,causing tumor involvement of the entire extrahepatic biliary *** these circumstances,hep-atopancreatoduodenectomy(HPD)has been proposed as a pro-cedure with curative intent[2,6,7].

关键词： pancreatoduodenectomy extrahepatic involvement

Surgical treatment of hepatocellular carcinoma in the era of COVID-19 pandemic:A comprehensive review of current recommendations

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World Journal of Clinical Cases 2021年第15期9卷 3517-3530页

作者： Alessandro Fancellu Valeria Sanna Fabrizio Scognamillo Claudio F Feo Gianpaolo Vidili Giuseppe Nigri Alberto porcu Department of Medical Surgical and Experimental SciencesUnit of General Surgery 2-Clinica ChirurgicaUniversity of SassariSassari 07100Italy Unit of Medical Oncology AOU SassariSassari 07100Italy Department of Medical Surgical and Experimental SciencesUnit of General Surgery 1-Patologia ChirurgicaUniversity of SassariSassari 07100Italy Department of Medical Surgical and Experimental SciencesUnit of Internal MedicineUniversity of SassariSassari 07100Italy Department of Medical and Surgical Sciences and Translational Medicine Sapienza University of RomeSt.Andrea University HospitalRome 00189Italy

The new coronavirus disease 2019 (COVID-19) pandemic has resulted in a globalhealth emergency that has also caused profound changes in the treatment ofcancer. The management of hepatocellular carcinoma (HCC) across the world hasbeen modified according to the scarcity of care resources that have been divertedmostly to face the surge of hospitalized COVID-19 patients. Oncological andhepatobiliary societies have drafted recommendations regarding the adaptation ofguidelines for the management of HCC to the current healthcare situation. Thisreview focuses on specific recommendations for the surgical treatment of HCC (i.e., hepatic resection and liver transplantation), which still represents the bestchance of cure for patients with very early and early HCC. While surgery shouldbe pursued for very selected patients in institutions where standards of care aremaintained, alternative or bridging methods, mostly thermoablation and transarterialtherapies, can be used until surgery can be performed. The prognosis ofpatients with HCC largely depends on both the characteristics of the tumour andthe stage of underlying liver disease. Risk stratification plays a pivotal role indetermining the most appropriate treatment for each case and needs to balancethe chance of cure and the risk of COVID-19 infection during *** recommendations have been critically reviewed to provide a reference forbest practices in the clinical setting, with adaptation based on pandemic trendsand categorization according to COVID-19 prevalence.

关键词： Hepatocellular carcinoma COVID-19 Hepatic resection Liver transplant Ablation

Pancreatic head excavation for tissue diagnosis may reduce unnecessary pancreaticoduode- nectomies in the setting of chronic pancreatitis

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Hepatobiliary & Pancreatic Diseases International 2017年第3期16卷 315-322页

作者： Alessandro Fancellu Giorgio C Ginesu Claudio F Feo Maria L Cossu Marco Puledda Antonio Pinna Alberto porcu Department of Clinical and Experimental Medicine Unit of General Surgery 2 - Clinica Chirurgica University of Sassari V.le San Pietro 43 07100 Sassari Italy

BACKGROUND： The necessity to obtain a tissue diagnosis of cancer prior to pancreatic surgery still remains an open debate. In fact, a non-negligible percentage of patients under- going pancreaticoduodenectomy （PD） for suspected cancer has a benign lesion at final histology. We describe an approach for patients with diagnostic uncertainty between cancer and chronic pancreatitis, with the aim of minimizing the incidence of PD for suspicious malignancy finally diagnosed as benign disease. METHODS： Eighty-eight patients （85.4%） with a clinicoradio- logical picture highly suggestive for malignancy received for- mal PD （group 1）. Fifteen patients （14.6%） in whom preopera- tive diagnosis was uncertain between pancreatic cancer and chronic pancreatitis underwent pancreatic head excavation （PHEX） for intraoperative tissue diagnosis （group 2）： those diagnosed as having cancer received PD, whereas those with chronic pancreatitis received pancreaticojejunostomy （P]）. RESULTS： No patient received PD for benign disease. All pa- tients in group I had adenocarcinoma on final histology. Eight patients of group 2 （53.3%） received PD after intraoperative diagnosis of cancer, whereas 7 （46.7%） received PJ because no malignancy was found at introperative frozen sections. No signs of cancer were encountered in patients receiving PHEX and PJ after a median follow-up of 42 months. Overall survival did not differ between patients receiving PD for cancer in the group 1 and those receiving PD for cancer after PHEX in the group 2 （P=0.509）. CONCLUSION： Although the described technique has been used in a very selected group of patients, our results suggest that PHEX for tissue diagnosis may reduce rates of unnecessary PD, when the preoperative diagnosis is uncertain between cancer and chronic pancreatitis.

关键词： pancreatic carcinoma chronic pancreatitis pancreaticoduodenectomy pancreatic head excavation

Modified Maximum Likelihood Estimation in Autoregressive Processes with Generalized Exponential Innovations

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Open Journal of Statistics 2014年第8期4卷 620-629页

作者： Bernardo Lagos-álvarez Guillermo Ferreira Emilio porcu Department of Statistics Universidad de Concepción Concepción Chile Department of Mathematics University Federico Santa María Valparaíso Chile

We consider a time series following a simple linear regression with first-order autoregressive errors belonging to the class of heavy-tailed distributions. The proposed model provides a useful generalization of the symmetrical linear regression models with independent error, since the error distribution covers both correlated innovations following a Generalized Exponential distribution. Furthermore, we derive the modified maximum likelihood (MML) estimators as an efficient alternative for estimating model parameters. Finally, we investigate the asymptotic properties of the proposed estimators. Our findings are also illustrated through a simulation study.

关键词： Autoregressive Time Series Model Maximum Likelihood Modified Maximum Likelihood Least Squares Generalized Exponential

How the COVID-19 pandemic has affected the colorectal cancer screening in Italy:A minireview

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World Journal of Gastrointestinal Oncology 2022年第8期14卷 1490-1498页

作者： Alessandro Fancellu Simone Veneroni Antonio Santoru Arianna Meloni Valeria Sanna Giorgio C Ginesu Giulia Deiana Panagiotis Paliogiannis Chiara Ninniri Teresa Perra Alberto porcu Department of Medical Surgicaland Experiemental SciencesUnit of General Surgery 2-Clinica ChirurgicaUniversity of SassariSassari 07100Italy Unit of Oncology AOU SassariSassari 07100Italy Department of Medical Surgicaland Experimental Sciences.Unit of PathologyUniversity of SassariSassari 07100Italy

The coronavirus disease 2019(COVID-19)pandemic has caused detrimental effects on many aspects of healthcare *** programs for the commonest malignancies,namely colorectal cancer(CRC),breast cancer and cervical cancer have been discontinued or interrupted since the beginning of restriction measures aimed to limit transmission of the new coronavirus *** evidence exists in favour of the role of screening campaigns in reducing mortality from *** fact,the majority of pre-malignant lesions of the colon and rectum can be diagnosed with colonoscopy and treated by endoscopic or surgical ***,colonoscopy screening allows the diagnosis of CRCs in their pre-clinical *** was one of the first European countries where a high level of COVID-19 infections and deaths was observed,and one of the first where lockdowns and strict measures were adopted to reduce the risk of COVID-19 diffusion among the population.A systematic review of the literature was performed,including the PubMed,Scopus,Web of Sciences,and Reference Citation Analysis databases,with the aim of critically evaluating the impact of the COVID-19 pandemic on CRC screening in *** found that reduction of CRC screening activity surpassed 50%in most endoscopic units,with almost 600000 fewer CRC screening exams conducted in the first 5 mo of 2020 vs the same period of *** the consequences of the discontinuation of endoscopy screening for the prognosis and mortality of CRC will be evident in the next few years,recent data confirm that CRC is currently treated at a more advanced stage than in the pre-COVID-19 *** delays in CRC prevention and early diagnosis may translate to increased CRC-specific mortality,world healthcare systems should adopt strategies to maintain the regularity of CRC screening during subsequent peaks of the COVID-19 pandemic,or future events that might hamper screening programs.

关键词： COVID-19 Colorectal cancer screening Italy Minireview

Supraclavicular lymph node metastases from malignant gastrointestinal stromal tumor of the jejunum: A case report with review of the literature

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World Journal of Gastroenterology 2017年第10期23卷 1920-1924页

作者： Chi Ma Shao-Long Hao Xin-Cheng Liu Jin-Yao Nin Guo-Chang Wu Li-Xin Jiang Alessandro Fancellu Alberto porcu Hai-Tao Zheng Department of Gastrointestinal and Thyroid Surgery Yuhuangding Hospital Affiliated to Qingdao University Qingdao University Medical College Unit of General Surgery Department of Clinical and Experimental Medicine University of Sassari

Gastrointestinal stromal tumors(GISTs) represent the most common mesenchymal tumors of the alimentary tract. These tumors may have different clinical and biological behaviors. Malignant forms usually spread via a hematogenous route, and lymph node metastases rarely occur. Herein, we report a patient with a jejunal GIST who developed supraclavicular lymph node metastasis. We conclude that lymphatic diffusion via the mediastinal lymphatic station to the supraclavicular lymph nodes can be a potential metastatic route for GISTs.

关键词： Gastrointestinal stromal tumor Metastasis Lymph nodes