A symplectic, symmetric algorithm for spatial evolution of particles in a time-dependent field

A symplectic, symmetric, second-order scheme is constructed for particle evolution in a time-dependent field with a fixed spatial step. The scheme is implemented in one space dimension and tested, showing excellent adequacy to experiment analysis.Comment: version 2; 16 p

Polycythemia vera and essential thrombocythemia with monoclonal gammopathy: experience of a single institution

IF 3.45

Rare and unusual bleeding manifestations in congenital bleeding disorders: an annotated review.

Epistaxis, superficial and deep hematomas, hemarthrosis, gastrointestinal bleeding, hematuria represent the most frequent hemorrhagic events in congenital coagulation disorders. Occasionally, bleeding manifestations occur in unusual sites or are peculiar. A clotting defect may alter the clinical aspect of skin conditions or infections (hemorrhagic scabies or varicella). Hemobilia may occur as a complication of transjugular liver biopsy in hemophilia or Bernard-Soulier syndrome. Hemarthrosis of small joints of feet and hands occur in patients with hemophilia treated with protease inhibitors. Intramedullary hematomas of long bones have been described in \u3b12-plasmin inhibitor or fibrinogen deficiencies. Spleen fracture with consequent hemoperitoneum has been reported in patients with fibrinogen deficiency. Rectus muscle sheath hematoma may occur in patients with factor VII (FVII)or FX deficiency. Acute or subacute intestinal obstruction may be caused by intramural wall hematomas in hemophilia and von Willebrand (vW)-disease. Physicians should always keep in mind that a congenital hemorrhagic disorder may cause bleeding in any tissue of the body and therefore alter the normal clinical features of a given disease

Virtual reality and feeling of falling: A physiological wearable tool for virtual reality sickness

Virtual reality (VR) approaches have recently found promising applications in the field of rehabilitation. However, prolonged immersion in a VR environment is known to occasionally cause sickness and discomfort, in both patients and healthy subjects. In the present study we assessed changes in Electrodermal Activity (EDA) as an estimate of Sympathetic Nervous System (SNS) activity in 16 healthy subjects performing 3 different tasks in a VR environment. Our aim is to collect preliminary evidence on the use of SNS activity as a potential marker to detect discomfort during VR experiences. SNS activity was quantified using a wearable device during the different conditions presented in the experiment. Results showed that EDA, more specifically Maximal Phasic activity and skin conductance differentiate among tasks, thus quantifying the SNS activity load of a task. In conclusion SNS activity markers derived from EDA have the potential to be used as a biomarker for VR experiences

Splenectomy after portal thrombosis in patients with polycythemia vera and essential thrombocythemia. Haematologica 2002; 87: 1180-1184 3,216

IF 4,19

Splenectomy after portal thrombosis in patients with polycythemia vera and essential thrombocythemia.

Background and Objectives. Polycythemia vera (PV) and essential thrombocythemia (ET) are two rare acquired myeloproliferative disorders (MPD) with frequent thrombotic and hemorrhagic complications. The occurrence of thrombosis in unusual sites, e.g. splanchnic vasculature, is a severe complication of these diseases. We describe a single-institution experience in patients with ET and PV, diagnosed in agreement with the Polycthemia Vera Study Group criteria, with portal vein thrombosis who did or did not undergo splenectomy. Design and Methods. The medical records and the followup outcome of 16 MPD patients with portal thrombosis who underwent splenectomy (group A1) and 16 who did not (group A2) were evaluated. Their median follow-up was, respectively, 13.45 and 10.49 years. The overall survival of these patients was compared with that of a population of 32 patients with MPD and no portal thrombosis (group B) matched for sex, age, diagnosis and duration of follow-up. Results. In group A1, 2 patients developed deep vein thrombosis, 1 patient had a surgical hemorrhage and 2 patients died early, one from acute infection, the other from bone marrow aplasia. Among the survivors, one male had a deep vein thrombosis and 1 developed a new portal thrombosis. Four patients died during the followup (median 9.48 years, range 3.17-25.1; 1 stroke, 2 gastrointestinal bleedings, 1 leukemic conversion). No difference was observed in the incidence of thrombotic or hemorrhagic complications or in the rate of deaths when group A1 was compared to the other groups. The use of antiplatelets drugs was statistically increased in group A1 after splenectomy, because portal vein thrombosis induced per se an increased use of therapeutic agents. No statistical difference was observed in overall survival between the different groups. Interpretation and Conclusions. 1) Bleeding and thrombosis are the leading causes of morbidity and mortality in ET and PV patients with portal vein thrombosis both with or without splenectomy. 2) Portal vein thrombosis, and sometimes splenectomy, requires increased use of drugs which may enhance the risk of leukemic transformation. In spite of this, the patients who survive the first post-splenectomy period may have a long and safe life

Realization and simulations of the new SPES Beam Cooler

International audienceIn order to allow a good separation of isotopes in a High Resolution Mass Spectrometer (HRMS), the transverse emittance and the energy spread of the beam should have very low values, for this reason a Beam Cooler (BC) is planned to be located between the ISOL target, i.e. the beam source, and the HRMS in the new project Selective Production of Exotic Species (SPES). In the SPES project the spectrometer resolution must be higher than dm/m=5E-5 and thus the features of the beam at the entrance of the HRMS should be at least emittance (95%, normalized) < 8.3E-3 pi mm mrad and sigma_E < 1.5eV. A new BC has been designed and realized by the Laboratoire de Physique Corpuscolaire (LPC) at Caen, France, for the SPES facility at Laboratori Nazionali di Legnaro (LNL), near Padova, Italy. BCs cool down the beam thanks to a dissipative process in which the thermal energy passes from the beam ions to another medium whose constituent is typically much lighter, Helium gas in our case. This process takes place inside a confinement system that on the one hand to limit the spread of the cooling medium, and on the other to allow the beam to continue along the required trajectory, in the presented device it is a row of radio frequency quadrupoles in an almost closed chamber. This document presents the main features of the new BC together with the results of a preliminary study where the beam dynamic has been simulated. The analysis embeds also the investigation of the gas distribution inside and outside the BC. The beam dynamic simulations are based on the Simion code while the estimation of the gas distribution is computed with MolFlow+. Simulations show that accurately setting the BC leads to a large improvement of the emittance while the energy spread still needs to be improved. Limiting the gas pressure in the acceleration zone seems to allow the required final boost

Realization and simulations of the new SPES Beam Cooler

International audienceIn order to allow a good separation of isotopes in a High Resolution Mass Spectrometer (HRMS), the transverse emittance and the energy spread of the beam should have very low values, for this reason a Beam Cooler (BC) is planned to be located between the ISOL target, i.e. the beam source, and the HRMS in the new project Selective Production of Exotic Species (SPES). In the SPES project the spectrometer resolution must be higher than dm/m=5E-5 and thus the features of the beam at the entrance of the HRMS should be at least emittance (95%, normalized) < 8.3E-3 pi mm mrad and sigma_E < 1.5eV. A new BC has been designed and realized by the Laboratoire de Physique Corpuscolaire (LPC) at Caen, France, for the SPES facility at Laboratori Nazionali di Legnaro (LNL), near Padova, Italy. BCs cool down the beam thanks to a dissipative process in which the thermal energy passes from the beam ions to another medium whose constituent is typically much lighter, Helium gas in our case. This process takes place inside a confinement system that on the one hand to limit the spread of the cooling medium, and on the other to allow the beam to continue along the required trajectory, in the presented device it is a row of radio frequency quadrupoles in an almost closed chamber. This document presents the main features of the new BC together with the results of a preliminary study where the beam dynamic has been simulated. The analysis embeds also the investigation of the gas distribution inside and outside the BC. The beam dynamic simulations are based on the Simion code while the estimation of the gas distribution is computed with MolFlow+. Simulations show that accurately setting the BC leads to a large improvement of the emittance while the energy spread still needs to be improved. Limiting the gas pressure in the acceleration zone seems to allow the required final boost