28 research outputs found
Adenocarcinoma in Caroli's Disease Treated by Liver Transplantation
Caroli's disease is characterized by congenital cystic dilatation of the intrahepatic bile ducts. In 7% of
casea a malignant tumor develops complicating the course of the disease
On complex-valued 2D eikonals. Part four: continuation past a caustic
Theories of monochromatic high-frequency electromagnetic fields have been
designed by Felsen, Kravtsov, Ludwig and others with a view to portraying
features that are ignored by geometrical optics. These theories have recourse
to eikonals that encode information on both phase and amplitude -- in other
words, are complex-valued. The following mathematical principle is ultimately
behind the scenes: any geometric optical eikonal, which conventional rays
engender in some light region, can be consistently continued in the shadow
region beyond the relevant caustic, provided an alternative eikonal, endowed
with a non-zero imaginary part, comes on stage. In the present paper we explore
such a principle in dimension We investigate a partial differential system
that governs the real and the imaginary parts of complex-valued two-dimensional
eikonals, and an initial value problem germane to it. In physical terms, the
problem in hand amounts to detecting waves that rise beside, but on the dark
side of, a given caustic. In mathematical terms, such a problem shows two main
peculiarities: on the one hand, degeneracy near the initial curve; on the other
hand, ill-posedness in the sense of Hadamard. We benefit from using a number of
technical devices: hodograph transforms, artificial viscosity, and a suitable
discretization. Approximate differentiation and a parody of the
quasi-reversibility method are also involved. We offer an algorithm that
restrains instability and produces effective approximate solutions.Comment: 48 pages, 15 figure
Roflumilast in moderate-to-severe chronic obstructive pulmonary disease treated with longacting bronchodilators: two randomised clinical trials
Background Patients with chronic obstructive pulmonary disease (COPD) have few options for treatment. The efficacy and safety of the phosphodiesterase-4 inhibitor roflumilast have been investigated in studies of patients with moderate-to-severe COPD, but not in those concomitantly treated with longacting inhaled bronchodilators. The effect of roflumilast on lung function in patients with COPD that is moderate to severe who are already being treated with salmeterol or tiotropium was investigated. Methods In two double-blind, multicentre studies done in an outpatient setting, after a 4-week run-in, patients older than 40 years with moderate-to-severe COPD were randomly assigned to oral roflumilast 500 mu g or placebo once a day for 24 weeks, in addition to salmeterol (M2-127 study) or tiotropium (M2-128 study). The primary endpoint was change in prebronchodilator forced expiratory volume in 1s (FEV(1)). Analysis was by intention to treat. The studies are registered with ClinicalTrials.gov, number NCT00313209 for M2-127, and NCT00424268 for M2-128. Findings In the salmeterol plus roflumilast trial, 466 patients were assigned to and treated with roflumilast and 467 with placebo; in the tiotropium plus roflumilast trial, 371 patients were assigned to and treated with roflumilast and 372 with placebo. Compared with placebo, roflumilast consistently improved mean prebronchodilator FEV(1) by 49 mL (p<0.0001) in patients treated with salmeterol, and 80 mL (p<0.0001) in those treated with tiotropium. Similar improvement in postbronchodilator FEV(1) was noted in both groups. Furthermore, roflumilast had beneficial effects on other lung function measurements and on selected patient-reported outcomes in both groups. Nausea, diarrhoea, weight loss, and, to a lesser extent, headache were more frequent in patients in the roflumilast groups. These adverse events were associated with increased patient withdrawal. Interpretation Roflumilast improves lung function in patients with COPD treated with salmeterol or tiotropium, and could become an important treatment for these patients
Rigorous Proofs for Cone-Beam Reconstruction
Cone beam reconstruction is a three-dimensional tomographic reconstruction technique with the potential capability of producing images with temporal contrast, and three-dimensional spatial resolution. In this paper we present a rigorous proof of the novel three-dimensional inversion formula developed by B. Smith and derive strict tipper bound« for the erro
Rigorous Proofs For Cone-Beam Reconstruction
Cone beam reconstruction is a three-dimensional tomographic reconstruction technique with the potential capability of producing images with temporal contrast, and three-dimensional spatial resolution.In this paper we present a rigorous proof of the novel three-dimensional inversion formula developed by B. Smith and derive strict tipper bound« for the erro