298 research outputs found
Mandatory multidisciplinary approach for the evaluation of the lymph node status in rectal cancer
Colorectal cancer is the third most frequently reported malignancy and also the third leading cancer-related cause of death worldwide. Lymph node evaluation, both preoperatively and postoperatively, represents an important aspect of the diagnosis and therapeutic strategy in colorectal cancer, such that an accurate preoperative staging is required for a correct therapeutic strategy. Treatment of rectal cancer with positive lymph nodes, a very important predictive prognostic parameter, is currently based on neoadjuvant chemoradiotherapy followed by total/ surgical mesorectal excision and adjuvant regimen.
Preoperative evaluation of the lymph node status in rectal cancer is based on endoscopic ultrasound and magnetic resonance imaging, but their accuracy, specificity, and sensitivity still require improvement. Postoperative evaluation also presents points of debate, especially related to the role of sentinel lymph node mapping and their final implication, represented by detection of micrometastases and isolated tumor cells. The pathologic interpretation of tumor deposits represents other points in discussion. From a surgical perspective, extended lateral lymph node dissection vs. abstinence and (neo)adjuvant therapeutic approach represent another unresolved issue.
This review presents the major controversies existing today in the treatment and pathologic interpretation of the lymph nodes in rectal cancer, the role/ indication and value of the lateral pelvic lymph node dissection, and the postoperative interpretation of the value of the micrometastatic disease and tumor deposits
Duality symmetry and the form fields of M-theory
In previous work we derived the topological terms in the M-theory action in
terms of certain characters that we defined. In this paper, we propose the
extention of these characters to include the dual fields. The unified treatment
of the M-theory four-form field strength and its dual leads to several
observations. In particular we elaborate on the possibility of a twisted
cohomology theory with a twist given by degrees greater than three.Comment: 12 pages, modified material on the differentia
M-theory and Characteristic Classes
In this note we show that the Chern-Simons and the one-loop terms in the
M-theory action can be written in terms of new characters involving the
M-theory four-form and the string classes. This sheds a new light on the
topological structure behind M-theory and suggests the construction of a theory
of `higher' characteristic classes.Comment: 8 pages. Error in gravitational term fixed; minor corrections;
reference and acknowledgement adde
Nilpotent Marsh and SUSY QM
We consider the nilpotent additions to classical trajectories in
supersymmetric and nonsupersymmetric theories. The condition of anilpotence of
action on some generalized solutions leads to the Witten supersymmetric
Lagrangian. The condition of anilpotence of topological charge is the same as
one of superpotential with spontaneous broken supersymmetry. We should vanish
half of Grassmann constants of integration, because in this case only we obtain
the same number of normalized bosonic and fermionic zero modes.Comment: 8 pages, Latex 2.09. Talk given at the conference in memory of V.I.
Ogievetski, Dubna, July, 1997. To be published in the Proceeding
The Elliptic curves in gauge theory, string theory, and cohomology
Elliptic curves play a natural and important role in elliptic cohomology. In
earlier work with I. Kriz, thes elliptic curves were interpreted physically in
two ways: as corresponding to the intersection of M2 and M5 in the context of
(the reduction of M-theory to) type IIA and as the elliptic fiber leading to
F-theory for type IIB. In this paper we elaborate on the physical setting for
various generalized cohomology theories, including elliptic cohomology, and we
note that the above two seemingly unrelated descriptions can be unified using
Sen's picture of the orientifold limit of F-theory compactification on K3,
which unifies the Seiberg-Witten curve with the F-theory curve, and through
which we naturally explain the constancy of the modulus that emerges from
elliptic cohomology. This also clarifies the orbifolding performed in the
previous work and justifies the appearance of the w_4 condition in the elliptic
refinement of the mod 2 part of the partition function. We comment on the
cohomology theory needed for the case when the modular parameter varies in the
base of the elliptic fibration.Comment: 23 pages, typos corrected, minor clarification
Fractional Branes in Non-compact Type IIA Orientifolds
We study fractional D-branes in the Type-IIA theory on a non-compact
orientifold of the orbifold C^3/Z_3 in the boundary state formalism. We find
that the fractional D0-branes of the orbifold theory become unstable due to the
presence of a tachyon, while there is a stable D-instanton whose tachyon gets
projected out. We propose that the D-instanton is obtained after tachyon
condensation. We evidence this by calculating the Whitehead group of the
Abelian category of objects corresponding to the boundary states as being
isomorphic to Z_2.Comment: 29 pages, Latex2e minor corrections. references updated. Version
accepted in JHE
Some Navigation Rules for D-Brane Monodromy
We explore some aspects of monodromies of D-branes in the Kahler moduli space
of Calabi-Yau compactifications. Here a D-brane is viewed as an object of the
derived category of coherent sheaves. We compute all the interesting
monodromies in some nontrivial examples and link our work to recent results and
conjectures concerning helices and mutations. We note some particular
properties of the 0-brane.Comment: LaTeX2e, 28 pages, 4 figures, some typos corrected and refs adde
On the relation between effective supersymmetric actions in different dimensions
We make two remarks: (i) Renormalization of the effective charge in a
4--dimensional (supersymmetric) gauge theory is determined by the same graphs
and is rigidly connected to the renormalization of the metric on the moduli
space of the classical vacua of the corresponding reduced quantum mechanical
system. Supersymmetry provides constraints for possible modifications of the
metric, and this gives us a simple proof of nonrenormalization theorems for the
original 4-dimensional theory. (ii) We establish a nontrivial relationship
between the effective (0+1)-dimensional and (1+1)-dimensional Lagrangia (the
latter represent conventional
Kahlerian sigma models).Comment: 15 pages, 2 figure
Mandatory multidisciplinary approach for the evaluation of the lymph node status in rectal cancer
Colorectal cancer is the third most frequently reported malignancy and also the third leading cancer-related cause of death worldwide. Lymph node evaluation, both preoperatively and postoperatively, represents an important aspect of the diagnosis and therapeutic strategy in colorectal cancer, such that an accurate preoperative staging is required for a correct therapeutic strategy. Treatment of rectal cancer with positive lymph nodes, a very important predictive prognostic parameter, is currently based on neoadjuvant chemoradiotherapy followed by total/ surgical mesorectal excision and adjuvant regimen.
Preoperative evaluation of the lymph node status in rectal cancer is based on endoscopic ultrasound and magnetic resonance imaging, but their accuracy, specificity, and sensitivity still require improvement. Postoperative evaluation also presents points of debate, especially related to the role of sentinel lymph node mapping and their final implication, represented by detection of micrometastases and isolated tumor cells. The pathologic interpretation of tumor deposits represents other points in discussion. From a surgical perspective, extended lateral lymph node dissection vs. abstinence and (neo)adjuvant therapeutic approach represent another unresolved issue.
This review presents the major controversies existing today in the treatment and pathologic interpretation of the lymph nodes in rectal cancer, the role/ indication and value of the lateral pelvic lymph node dissection, and the postoperative interpretation of the value of the micrometastatic disease and tumor deposits
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