The gravitational path integral and trace of the diffeomorphisms

I give a resolution of the conformal mode divergence in the Euclidean gravitational path-integral by isolating the trace of the diffeomorphisms and its contribution to the Faddeev-Popov measure.Comment: 20 pgs

Geometric Transition versus Cascading Solution

We study Vafa's geometric transition and Klebanov - Strassler solution from various points of view in M-theory. In terms of brane configurations, we show the detailed equivalences between the two models. In some limits, both models have an alternative realization as fourfolds in M-theory with appropriate G-fluxes turned on. We discuss some aspects of the fourfolds including how to see the transition and a possible extension to the non-supersymmetric case.Comment: 34 pages, LaTex, 2 figures; v2: Some comments added and references updated. Final version to appear in JHE

KK-Masses in Dipole Deformed Field Theories

We reconsider aspects of non-commutative dipole deformations of field theories. Among our findings there are hints to new phases with spontaneous breaking of translation invariance (stripe phases), similar to what happens in Moyal-deformed field theories. Furthermore, using zeta-function regularization, we calculate quantum corrections to KK-state masses. The corrections coming from non-planar diagrams show interesting but non-universal behaviour. Depending on the type of interaction the corrections can make the KK-states very heavy but also very light or even tachyonic. Finally we point out that the dipole deformation of QED is not renormalizable!Comment: 21 pages, 5 figures, uses axodraw.sty, JHEP3.cls; v2:revised version with minor change

Identification of Haptic Based Guiding Using Hard Reins

This paper presents identifications of human-human interaction in which one person with limited auditory and visual perception of the environment (a follower) is guided by an agent with full perceptual capabilities (a guider) via a hard rein along a given path. We investigate several identifications of the interaction between the guider and the follower such as computational models that map states of the follower to actions of the guider and the computational basis of the guider to modulate the force on the rein in response to the trust level of the follower. Based on experimental identification systems on human demonstrations show that the guider and the follower experience learning for an optimal stable state-dependent novel 3rd and 2nd order auto-regressive predictive and reactive control policies respectively. By modeling the follower's dynamics using a time varying virtual damped inertial system, we found that the coefficient of virtual damping is most appropriate to explain the trust level of the follower at any given time. Moreover, we present the stability of the extracted guiding policy when it was implemented on a planar 1-DoF robotic arm. Our findings provide a theoretical basis to design advanced human-robot interaction algorithms applicable to a variety of situations where a human requires the assistance of a robot to perceive the environment

Compactification of IIB Theory with Fluxes and Axion-Dilaton String Cosmology

Compactification of type IIB theory on torus, in the presence of fluxes, is considered. The reduced effective action is expressed in manifestly S-duality invariant form. Cosmological solutions of the model are discussed in several cases in the Pre-Big Bang scenario.Comment: 22 page

Understanding Fields Using Strings: A Review for Particle Physicists

In addition to being a prime candidate for a fundamental unified theory of all interactions in nature, string theory provides a natural setting to understand gauge field theories. This is linked to the concept of "D-branes": extended, solitonic excitations of string theory which can be studied using techniques of string theory and which support gauge fields localized along their world-volumes. It follows that the techniques of string theory can be very useful even for those particle physicists who are not specifically interested in unification and/or quantum gravity. In this talk I attempt to review how strings help us to understand fields. The discussion is restricted to 3+1 spacetime dimensions.Comment: LaTeX, 22 pages, 4 eps figures (included); v2: Name of conference corrected, no other change

A study of the effect of pre-radiation on healing of surgical wounds in the treatment of cancers of the head and neck

Background: Radiation therapy is an established modality in the treatment of head and neck cancer patients. It is used alone or in combination with surgery and chemotherapy. Although radiotherapy is useful to affect tumour death, it also exerts a deleterious effect on surrounding normal tissues. These effects are either acute or can manifest months or years after the treatment. The chronic wounds are a result of impaired wound healing. Compromised wound healing in irradiated tissues is a common and challenging clinical problem.Methods: A prospective observational study was done in a tertiary care teaching institute, Kolkata. The effect of radiation on surgery of cancers of head and neck was studied in 50 patients. The patients were divided into 2 groups of 25 each. The cases in the first group were irradiated prior to surgery and those on the second group were operated upon without any pre-radiation.Results: The highest incidence of wound complications in those patients who were operated upon within 2 weeks to 6 months of completion of RT (83.33%). Patients who had their blood Hb level at or above 11 gm% developed less number of wound complications (34.78%) as compared to those who had their blood Hb level between 8-11 gm% where complication rate was 48.15%. Those patients who had their oral cavity or pharynx opened during surgery had a much higher incidence of wound complications (54.54%) than whose oral cavity or pharynx were not interfered with (17.64%). Wound infection was 36% in the irradiated group and 12% in the non-irradiated group. Separation of wound edges or skin necrosis followed in 28% cases in the pre-radiated group and in 8% cases in the non-pre-radiated group.Conclusions: Radiotherapy is an integral modality of head and neck cancer therapy. Compromised wound healing is an important side effect of radiation therapy. All sorts of local complications as wound infection and necrosis, or ocutaneous fistulae, carotid artery perforation etc. are more pronounced in patients, who received prior radiotherapy. The complication of surgery after radiotherapy was found to be more pronounced between 2 weeks to 6 months in this series