39 research outputs found
Noncommutative resolutions of ADE fibered Calabi-Yau threefolds
In this paper we construct noncommutative resolutions of a certain class of Calabi-Yau threefolds studied by F. Cachazo, S. Katz and C. Vafa. The threefolds under consideration are fibered over a complex plane with the fibers being deformed Kleinian singularities. The construction is in terms of a noncommutative algebra introduced by V. Ginzburg, which we call the "N=1 ADE quiver algebra"
Sheaves on fibered threefolds and quiver sheaves
This paper classifies a class of holomorphic D-branes, closely related to
framed torsion-free sheaves, on threefolds fibered in resolved ADE surfaces
over a general curve C, in terms of representations with relations of a twisted
Kronheimer--Nakajima-type quiver in the category Coh(C) of coherent sheaves on
C. For the local Calabi--Yau case C\cong\A^1 and special choice of framing, one
recovers the N=1 ADE quiver studied by Cachazo--Katz--Vafa.Comment: 13 pages, 2 figures, minor change
Diffeomorphisms and families of Fourier-Mukai transforms in mirror symmetry
Assuming the standard framework of mirror symmetry, a conjecture is
formulated describing how the diffeomorphism group of a Calabi-Yau manifold Y
should act by families of Fourier-Mukai transforms over the complex moduli
space of the mirror X. The conjecture generalizes a proposal of Kontsevich
relating monodromy transformations and self-equivalences. Supporting evidence
is given in the case of elliptic curves, lattice-polarized K3 surfaces and
Calabi-Yau threefolds. A relation to the global Torelli problem is discussed.Comment: Approx. 20 pages LaTeX. One reference adde
ParadigmavĂĄltĂĄs a csontmetasztĂĄzisok sebĂ©szetĂ©ben. I. VĂ©gtagi Ă©s medencelokalizĂĄciĂłjĂș ĂĄttĂ©tek
According to the statistical data of tumor registries the incidence of cancer has increased in the last decade, however the mortality shows only a slight change due to the new and effective multimodal treatments. The aim of our overview article is to present the changes in the survival of the metastatic patients, and to demonstrate which factors influence their prognosis. The improvement of survival resulted in a more active surgical role both in metastases of the bone of the extremities and the pelvis. We present a diagnostic flow chart and current options for the reconstruction of the different regions of the bone and skeleton, and we will discuss their potential advantages, disadvantages and complications. It is evident that apart from the impending and pathological fracture surgery it is not the first choice of treatment but rather a palliative measure. The aim of surgery is to alleviate pain, to regain mobility and improve quality of life. If possible minimal invasive techniques are performed, as they are less demanding and allow fast rehabilitation for the patient, and they are solutions that last for a lifetime. In optimal conditions radical curative surgery can be performed in about 10 to 15 per cent of the cases, and better survival is encouraging. Orv Hetil. 2017; 158(40): 1563-1569
A Ewing-sarcomĂĄs betegek tĂŒnetmentes tĂșlĂ©lĂ©si esĂ©lyeinek Ă©rtĂ©kelĂ©se a GyermekonkolĂłgiai SzekciĂł eredmĂ©nyei alapjĂĄn
Correlation between different prognostic factors and the overall
survival of Ewing's sarcoma patients has been investigted. In
this study data have been selected from the databank of
Hungarian Pediatric Oncologist Section (1988-1999) (n=65).
Whenever it was possible statistical analysis has been
performed. Results: In our patients time interval from the
primary symptoms to the diagnosis was 2-16 months. The average
event-free survival in patients suffering from Ewing's sarcoma
without metastasis is 0.39. Meanwhile, this value in patients
with pulmonary or other metatasis is 0.24 (Kaplan-Meier
analysis). Conclusion: Our results show a moderate difference
between the Hungarian and the international event-free survival.
Late detection is one of the answers of this discrepancy
Non-commutative desingularization of determinantal varieties, I
We show that determinantal varieties defined by maximal minors of a generic
matrix have a non-commutative desingularization, in that we construct a maximal
Cohen-Macaulay module over such a variety whose endomorphism ring is
Cohen-Macaulay and has finite global dimension. In the case of the determinant
of a square matrix, this gives a non-commutative crepant resolution.Comment: 52 pages, 3 figures, all comments welcom
Structure of a large social network
We study a social network consisting of over individuals, with a
degree distribution exhibiting two power scaling regimes separated by a
critical degree , and a power law relation between degree and
local clustering. We introduce a growing random model based on a local
interaction mechanism that reproduces all of the observed scaling features and
their exponents. Our results lend strong support to the idea that several very
different networks are simultenously present in the human social network, and
these need to be taken into account for successful modeling.Comment: 5 pages, 5 figure
Curve counting via stable pairs in the derived category
For a nonsingular projective 3-fold , we define integer invariants
virtually enumerating pairs where is an embedded curve and
is a divisor. A virtual class is constructed on the associated
moduli space by viewing a pair as an object in the derived category of . The
resulting invariants are conjecturally equivalent, after universal
transformations, to both the Gromov-Witten and DT theories of . For
Calabi-Yau 3-folds, the latter equivalence should be viewed as a wall-crossing
formula in the derived category.
Several calculations of the new invariants are carried out. In the Fano case,
the local contributions of nonsingular embedded curves are found. In the local
toric Calabi-Yau case, a completely new form of the topological vertex is
described.
The virtual enumeration of pairs is closely related to the geometry
underlying the BPS state counts of Gopakumar and Vafa. We prove that our
integrality predictions for Gromov-Witten invariants agree with the BPS
integrality. Conversely, the BPS geometry imposes strong conditions on the
enumeration of pairs.Comment: Corrected typos and duality error in Proposition 4.6. 47 page
Contrastive focus and emphasis
The paper puts forward a discourse-semantic account of the notoriously evasive phenomena of contrastivity and emphasis. Based on new evidence from Chadic, it is argued that occurrences of focus that are treated in terms of âcontrastive focusâ, âkontrastâ (VallduvĂ-Vilkuna 1998) or âidentificational focusâ (Ă. Kiss 1998) in the literature should not be analyzed in familiar semantic terms as involving the introduction and subsequent exclusion of alternatives. Rather, an adequate analysis must take into account discourse-semantic notions like âhearer expectationâ or âdiscourse expectabilityâ of the focused content in a given discourse situation. The less expected the focus content is judged to be for the hearer, relative to the Common Ground, the more likely a speaker is to mark the focus constituent by means of special grammatical devices, thus giving rise to emphasis