494 research outputs found
Probabilistic representation for solutions of an irregular porous media type equation: the degenerate case
We consider a possibly degenerate porous media type equation over all of
with , with monotone discontinuous coefficients with linear
growth and prove a probabilistic representation of its solution in terms of an
associated microscopic diffusion. This equation is motivated by some singular
behaviour arising in complex self-organized critical systems. The main idea
consists in approximating the equation by equations with monotone
non-degenerate coefficients and deriving some new analytical properties of the
solution
Model selection for a semi - Markov continuous time regression observed in the discrete time moments
Global attractors for Cahn-Hilliard equations with non constant mobility
We address, in a three-dimensional spatial setting, both the viscous and the
standard Cahn-Hilliard equation with a nonconstant mobility coefficient. As it
was shown in J.W. Barrett and J.W. Blowey, Math. Comp., 68 (1999), 487-517, one
cannot expect uniqueness of the solution to the related initial and boundary
value problems. Nevertheless, referring to J. Ball's theory of generalized
semiflows, we are able to prove existence of compact quasi-invariant global
attractors for the associated dynamical processes settled in the natural
"finite energy" space. A key point in the proof is a careful use of the energy
equality, combined with the derivation of a "local compactness" estimate for
systems with supercritical nonlinearities, which may have an independent
interest. Under growth restrictions on the configuration potential, we also
show existence of a compact global attractor for the semiflow generated by the
(weaker) solutions to the nonviscous equation characterized by a "finite
entropy" condition
Random attractors for degenerate stochastic partial differential equations
We prove the existence of random attractors for a large class of degenerate
stochastic partial differential equations (SPDE) perturbed by joint additive
Wiener noise and real, linear multiplicative Brownian noise, assuming only the
standard assumptions of the variational approach to SPDE with compact
embeddings in the associated Gelfand triple. This allows spatially much rougher
noise than in known results. The approach is based on a construction of
strictly stationary solutions to related strongly monotone SPDE. Applications
include stochastic generalized porous media equations, stochastic generalized
degenerate p-Laplace equations and stochastic reaction diffusion equations. For
perturbed, degenerate p-Laplace equations we prove that the deterministic,
infinite dimensional attractor collapses to a single random point if enough
noise is added.Comment: 34 pages; The final publication is available at
http://link.springer.com/article/10.1007%2Fs10884-013-9294-
The role of pancreatic islands transplantation in the management of chronic conditions
Institutul Clinic Fundeni, România, București, Al XIII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” și al III-lea Congres al Societății de Endoscopie, Chirurgie miniminvazivă și Ultrasonografie ”V.M.Guțu” din Republica MoldovaIntroducere: Diabetul zaharat reprezintă o problemă de sănătate la nivel mondial, în primul rând datorită numarului mare de pacienți
(se estimează că în 2015, 1 din 11 adulți suferea de diabet așteptându-se ca până în 2040, 1 din 10 adulți să fie diabetic); în al doilea
rând, mortalitatea prin diabet depașește mortalitatea sumată prin boli răspândite ca malaria, HIV/SIDA și tuberculoza; nu în ultimul
rand, costurile sistemelor de sănătate pentru o persoană diabetică sunt de 2.3 ori mai mari decât pentru o persoană nondiabetică.
Transplantul de insule pancreatice ca terapie în diabetul zaharat, reprezintă o metodă sigură și eficientă, care implică o intervenție
chirurgicală relativ ușoara, cu o morbiditate scăzuta și o mortalitate aproape de 0, în comparație cu transplantul de pancreas integral.
Rezultatele depind însa de procesul de izolare a insulelor pancreatice, un proces complex, care implică costuri ridicate.
Material și metode: Între anii 2007-2012 au avut loc 20 de recoltari în bloc spleno-pancreatico-duodenale, în cadrul recoltărilor
multiorgan realizate de echipa de prelevare din IC Fundeni (în 2 cazuri s-a recoltat în acest bloc și ficatul). Pancreasul recoltat s-a
folosit în 2 cazuri la transplantul de pancreas integral, iar in celelalte 18 cazuri, la obținerea insulelor pancreatice. Principalul rezultat a
fost formarea unor echipe naționale calificate in prelevarea pancreasului și stăpânirea tehnicii de izolare a insulelor pancreatice, fapt
ce reprezintă un prim pas în implementarea clinică a unui Program Național de Transplant de Insule Pancreatice. Ca implementare
clinică a acestui procedeu, s-a realizat primul allotransplant de insule pancreatice din România simultan cu transplantul de ficat la un
pacient în vârsta de 40 ani, cirotic, cu diabet zaharat insulino-dependent. O altă indicație a transplantului de insule pancreatice a fost
managementul pancreatitei cronice. Pancreatectomia totală urmată de autotransplant de insule pancreatice reprezintă o bună opțiune
în tratarea pancreatitei cronice, în special forma cu duct îngust, care chiar și cu necesarul suplimentar de insulină exogenă, asigură
un control mai eficient al diabetului prin secreția de lungă durată a insulinei și peptidului C.
Rezultate: În acest scop s-a realizat un autotransplant de insule pancreatice la o pacientă cu pancreatectomie totală pentru pancreatită
cronică. Indicația chirurgicală de rezecție pancreatică a fost sindromul algic permanent, refractar la antalgice majore si episoadele de
pancreatită acută recurente.
Concluzii: Rezultatele acestui studiu sunt promiţătoare şi situează şi România pe harta ţărilor care au ca preocupare folosirea
transplantului de insule pancreatice în managementul diabetului zaharat şi al pancreatitei cronice.Background: Diabetes mellitus is a global health problem, primarily due to the large number of patients (it is estimated that 20%
of patients in 2015, 1 out of 11 adults were diabetic, with one out of 10 adults being diabetic by 2040); secondly, diabetes mortality
outweighs the overall mortality rate through diseases such as malaria, HIV / AIDS and tuberculosis; Last but not least, the health care
costs for a diabetic person are 2.3 times higher than for a non-diabetic person. Transplantation of pancreatic islets as a therapy in
diabetes is a safe and effective method involving relatively easy surgery with low morbidity and mortality close to 0, compared to full
pancreas transplantation. The results depend, however, on the isolating process of the pancreatic islands, a complex process that
involves high costs.
Methods and materials: Between 2007-2012, there were 20 harvests in the spleno-pancreatic-duodenal block, during the multiorgan
harvests made by the sampling team from IC Fundeni (in 2 cases it was harvested in this block and the liver). The harvested pancreas
was used in 2 cases for whole pancreas transplantation, and in the other 18 cases, the pancreatic islets were obtained. The main
result was the formation of qualified national teams in pancreas extraction and the isolation of pancreatic islands, which is a first step
in the clinical implementation of a National Pancreatic Transplantation Program. As a clinical implementation of this procedure, the
first allotransplant of pancreatic islets in Romania was performed simultaneously with liver transplantation in a 40 year old, cirrhotic,
insulin-dependent diabetes mellitus. Another indication of pancreatic islet transplantation was the management of chronic pancreatitis.
Total pancreatectomy followed by pancreatic islet transplantation is a good option in the treatment of chronic pancreatitis, particularly
narrow-duct form, which even with the extra exogenous insulin requirement, provides more efficient control of diabetes by long-term
secretion of insulin and peptide C.
Results: For this purpose a pancreatic islet transplant was performed in a patient with total pancreatectomy for chronic pancreatitis.
The surgical indication of pancreatic resection was permanent algic syndrome, refractory to major antalgics, and recurrent acute
pancreatitis episodes.
Conclusion: The results of this study are promising and places Romania on the map of countries that are concerned with the use of
pancreatic islet transplantation in the management of diabetes mellitus and chronic pancreatitis
Weak formulation for singular diffusion equation with dynamic boundary condition
In this paper, we propose a weak formulation of the singular diffusion
equation subject to the dynamic boundary condition. The weak formulation is
based on a reformulation method by an evolution equation including the
subdifferential of a governing convex energy. Under suitable assumptions, the
principal results of this study are stated in forms of Main Theorems A and B,
which are respectively to verify: the adequacy of the weak formulation; the
common property between the weak solutions and those in regular problems of
standard PDEs.Comment: 23 page
On a Stochastic Wave Equation Driven by a Non-Gaussian Levy Process
This paper investigates a damped stochastic wave equation driven by a
non-Gaussian Levy noise. The weak solution is proved to exist and be unique.
Moreover we show the existence of a unique invariant measure associated with
the transition semigroup under mild conditions.Comment: 17 page
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