2,008 research outputs found
Index of elliptic operators for a diffeomorphism
We develop elliptic theory of operators associated with a diffeomorphism of a
closed smooth manifold. The aim of the present paper is to obtain an index
formula for such operators in terms of topological invariants of the manifold
and of the symbol of the operator. The symbol in this situation is an element
of a certain crossed product. We express the index as the pairing of the class
in K-theory defined by the symbol and the Todd class in periodic cyclic
cohomology of the crossed product.Comment: 37 page
Discrete breathers assist energy transfer to ac driven nonlinear chains
One-dimensional chain of pointwise particles harmonically coupled with
nearest neighbors and placed in six-order polynomial on-site potentials is
considered. Power of the energy source in the form of single ac driven
particles is calculated numerically for different amplitudes and
frequencies within the linear phonon band. The results for the on-site
potentials with hard and soft nonlinearity types are compared. For the
hard-type nonlinearity, it is shown that when the driving frequency is close to
(far from) the {\em upper} edge of the phonon band, the power of the energy
source normalized to increases (decreases) with increasing . In
contrast, for the soft-type nonlinearity, the normalized power of the energy
source increases (decreases) with increasing when the driving frequency is
close to (far from) the {\em lower} edge of the phonon band. Our further
demonstrations indicate that, in the case of hard (soft) anharmonicity, the
chain can support movable discrete breathers (DBs) with frequencies above
(below) the phonon band. It is the energy source quasi-periodically emitting
moving DBs in the regime with driving frequency close to the DBs frequency,
that induces the increase of the power. Therefore, our results here support the
mechanism that the moving DBs can assist energy transfer from the ac driven
particle to the chain.Comment: 11 pages, 13 figure
Elliptic operators on manifolds with singularities and K-homology
It is well known that elliptic operators on a smooth compact manifold are
classified by K-homology. We prove that a similar classification is also valid
for manifolds with simplest singularities: isolated conical points and fibered
boundary. The main ingredients of the proof of these results are: an analog of
the Atiyah-Singer difference construction in the noncommutative case and an
analog of Poincare isomorphism in K-theory for our singular manifolds.
As applications we give a formula in topological terms for the obstruction to
Fredholm problems on manifolds with singularities and a formula for K-groups of
algebras of pseudodifferential operators.Comment: revised version; 25 pages; section with applications expande
Classical approach in duodenopancreatectomy - the key to success of a controversial intervention
Secția IV Chirurgie, Secția Radiologie, Secția Gastoenterologie, Spital ”Sf. Spiridon”, U.M.F. “Grigore T. Popa”, Iași, România, 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: Duodenopancreatectomia cefalică (DPC) este considerată tratamentul standard pentru tumorile periampulare. În
pofida evoluției în chirurgia pancreatică, morbiditatea postoperatorie după DPC rămâne crescută. În timp ce rata mortalității asociate
intervenției chirurgicale a scăzut la mai puțin de 4%, morbiditatea postoperatorie se menține la mai mult de 50%, datorate în special
anastomozei pancreaticojejunale, principala vulnerabilitate a chirurgiei pancreatice.
Material și metode: Autorii prezintă un studiu pe 5 ani, între ianuarie 2014 și aprilie 2019, pe un lot de 17 pacienți la care s-a practicat
DPC cu reconstrucție clasică tip Whipple Child, cu 2 variante de anastomoză pancretico-jejunală. Media de vârstă a fost de 58,5.
Rezultate: Mortalitatea imediat postoperatorie în lotul studiat a fost de 0%, iar morbiditatea a fost reprezentată de 1 caz de fistulă
pancreatică și 2 cazuri de hemoragii postoperatorii. Supraviețuirea la 1 an a fost de 64,7%, 5 pacienți fiind pierduți din supraveghere
și 1 deces.
Concluzii: Fistula pancreatică, prin complicațiile cu pericol vital ca de exemplu hemoargia și peritonita, este principala cauză de
morbiditate și mortalitate după duodenopancreatectomie cefalică. Factorii care contribuie la această complicație sunt reprezentați de
textura moale a țesutului pancratic și de diametrul subțire al ductului pancreatic.Introduction: Pancreaticoduodenectomy (PD) is considered the standard treatment for periampullary tumors. Despite progresses
in pancreatic surgery, the postoperative morbidity after PD remains high. While the operation-associated mortality rate of pancreatic
surgery has decreased to less than 4%, the postoperative morbidity rate is reported to be as high as 50%, largely due to the
pancreaticojejunal anastomosis, the major vulnerability of pancreatic surgery.
Material and methods: The authors present a study between January 2014 and April 2019, on a series of 17 patients with PD with
classical reconstruction type Whipple Child, with 2 types of pancreaticojejunal anatomosis. The median age was 58,5.
Results: Postoperative mortality in the study was 0%, and morbidity was 1 case of pancreatic fistula and 2 postoperative bleeding.
The survival at 1 year was about 64,7%, 5 patients were lost under surveillance and one death.
Conclusions: Pancreatic fistula, with life-threatening complications, such as postoperative hemorrhage and peritonitis, is the most
important cause of morbidity and mortality in PD. Factors contributing to this complication are: soft pancreatic tissue texture and small
pancreatic duct diameter
Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan
This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good
- …