966 research outputs found
Novel Ambiguities in the Seiberg-Witten Map and the Emergent Gravity
A homogeneous part of the Seiberg-Witten gauge equivalence relation for gauge
fields can lead to solutions that involve matter fields in such a way that the
gauge equivalence and the dimensional and index structures are preserved. In
particular, we consider scalar fields coupled to U(1) gauge fields. The matter
fields appear non-linearly in the map. As an application, we analyze the
implication of this ambiguity to emergent gravity at the first order in
noncommutative parameter and show that the new ambiguity restores the
possibility of conformal coupling of real scalar density field that is coupled
non-minimally to the emergent gravity induced by gauge fields -- a possibility
that is strictly not allowed if we consider only the already known ambiguity in
the Seiberg-Witten map.Comment: JHEP style, 10 pages, minor corrections, a version published in JHE
Dynamics of Diblock Copolymers in Dilute Solutions
We consider the dynamics of freely translating and rotating diblock (A-B),
Gaussian copolymers, in dilute solutions. Using the multiple scattering
technique, we have computed the diffusion and the friction coefficients D_AB
and Zeta_AB, and the change Eta_AB in the viscosity of the solution as
functions of x = N_A/N and t = l_B/l_A, where N_A, N are the number of segments
of the A block and of the whole copolymer, respectively, and l_A, l_B are the
Kuhn lengths of the A and B blocks. Specific regimes that maximize the
efficiency of separation of copolymers with distinct "t" values, have been
identified.Comment: 20 pages Revtex, 7 eps figures, needs epsf.tex and amssymb.sty,
submitted to Macromolecule
Towards Full-Body Gesture Analysis and Recognition
With computers being embedded in every walk of our life, there is an increasing demand forintuitive devices for human-computer interaction. As human beings use gestures as importantmeans of communication, devices based on gesture recognition systems will be effective for humaninteraction with computers. However, it is very important to keep such a system as non-intrusive aspossible, to reduce the limitations of interactions. Designing such non-intrusive, intuitive, camerabasedreal-time gesture recognition system has been an active area of research research in the fieldof computer vision.Gesture recognition invariably involves tracking body parts. We find many research works intracking body parts like eyes, lips, face etc. However, there is relatively little work being done onfull body tracking. Full-body tracking is difficult because it is expensive to model the full-body aseither 2D or 3D model and to track its movements.In this work, we propose a monocular gesture recognition system that focuses on recognizing a setof arm movements commonly used to direct traffic, guiding aircraft landing and for communicationover long distances. This is an attempt towards implementing gesture recognition systems thatrequire full body tracking, for e.g. an automated recognition semaphore flag signaling system.We have implemented a robust full-body tracking system, which forms the backbone of ourgesture analyzer. The tracker makes use of two dimensional link-joint (LJ) model, which representsthe human body, for tracking. Currently, we track the movements of the arms in a video sequence,however we have future plans to make the system real-time. We use distance transform techniquesto track the movements by fitting the parameters of LJ model in every frames of the video captured.The tracker\u27s output is fed a to state-machine which identifies the gestures made. We haveimplemented this system using four sub-systems. Namely1. Background subtraction sub-system, using Gaussian models and median filters.2. Full-body Tracker, using L-J Model APIs3. Quantizer, that converts tracker\u27s output into defined alphabets4. Gesture analyzer, that reads the alphabets into action performed.Currently, our gesture vocabulary contains gestures involving arms moving up and down which canbe used for detecting semaphore, flag signaling system. Also we can detect gestures like clappingand waving of arms
Continuum Theory of Polymer Crystallization
We present a kinetic model of crystal growth of polymers of finite molecular
weight. Experiments help to classify polymer crystallization broadly into two
kinetic regimes. One is observed in melts or in high molar mass polymer
solutions and is dominated by nucleation control with , where is the growth rate and is the super-cooling. The
other is observed in low molar mass solutions (as well as for small molecules)
and is diffusion controlled with , for small . Our
model unifies these two regimes in a single formalism. The model accounts for
the accumulation of polymer chains near the growth front and invokes an
entropic barrier theory to recover both limits of nucleation and diffusion
control. The basic theory applies to both melts and solutions, and we
numerically calculate the growth details of a single crystal in a dilute
solution. The effects of molecular weight and concentration are also determined
considering conventional polymer dynamics. Our theory shows that entropic
considerations, in addition to the traditional energetic arguments, can capture
general trends of a vast range of phenomenology. Unifying ideas on
crystallization from small molecules and from flexible polymer chains emerge
from our theory.Comment: 37 double-spaced pages including 8 figures, submitted to the Journal
of Chemical Physic
Optimization of Ozonation Process for the Reduction of Excess Sludge Production from Activated Sludge Process of Sago Industry Wastewater Using Central Composite Design
Sago industries effluent containing large amounts of organic content produced excess sludge which is a serious problem in wastewater treatment. In this study ozonation has been employed for the reduction of excess sludge production in activated sludge process. Central composite design is used to study the effect of ozone treatment for the reduction of excess sludge production in sago effluent and to optimise the variables such as pH, ozonation time, and retention time. ANOVA showed that the coefficient determination value (R2) of VSS and COD reduction were 0.9689 and 0.8838, respectively. VSS reduction (81%) was achieved at acidic pH 6.9, 12 minutes ozonation, and retention time of 10 days. COD reduction (87%) was achieved at acidic pH 6.7, 8 minutes of ozonation time, and retention time of 6 days. Low ozonation time and high retention time influence maximum sludge reduction, whereas low ozonation time with low retention time was effective for COD reduction
Bosonic resonating valence bond wave function for doped Mott insulators
We propose a new class of ground states for doped Mott insulators in the
electron second-quantization representation. They are obtained from a bosonic
resonating valence bond (RVB) theory of the t-J model. At half filling, the
ground state describes spin correlations of the S=1/2 Heisenberg model very
accurately. Its spin degrees of freedom are characterized by RVB pairing of
spins, the size of which decreases continuously as holes are doped into the
system. Charge degrees of freedom emerge upon doping and are described by
twisted holes in the RVB background. We show that the twisted holes exhibit an
off diagonal long range order (ODLRO) in the pseudogap ground state, which has
a finite pairing amplitude, but is short of phase coherence. Unpaired spins in
such a pseudogap ground state behave as free vortices, preventing
superconducting phase coherence. The existence of nodal quasiparticles is also
ensured by such a hidden ODLRO in the ground state, which is
non-Fermi-liquid-like in the absence of superconducting phase coherence. Two
distinct types of spin excitations can also be constructed. The superconducting
instability of the pseudogap ground state is discussed and a d-wave
superconducting ground state is obtained. This class of pseudogap and
superconducting ground states unifies antiferromagnetism, pseudogap,
superconductivity, and Mott physics into a new state of matter.Comment: 28 pages, 5 figures, final version to appear in Phys. Rev.
Evaluation of patients with swallowing difficulties by modified barium swallow.
Patients with swallowing difficulties are commonly
encountered in the ENT OPD.Swallowing disorders can occur at any age but it is
more common in the elderly patients.Neurological causes and malignancy account
for the main reason in most of the cases.The modified barium swallow provides
information about the complex split second events underlying the swallowing
process. We can evaluate the effectiveness of swallowing manouveres by which
we can prevent aspiration in patients with pharyngeal retention.
AIMS
1.To study the various phases of swallowing in patients with dysphagia by
modified barium swallow
2.To identify the patients with risk of aspiration during swallowing
3.To study the effectiveness of swallowing manouveres by the modified barium
swallow technique
Materials and methods:
200 patients who attended ear, nose, and
throat out patient department with history of swallowing difficulties for more than 3 months were included in the study.Modified barium swallow was done in all
these patients.
Patients with risk of aspiration were detected by the amount
of pharyngeal retention in the pyriform sinuses and vallecula after swallowing.The
patients with grade 3 severe form of pharyngeal coating were given training for
postural technique and swallowing manoeuvres to prevent aspiration.
Results:
Out of the 200 patients, 92 patients were found to have
abnormal findings during the study. Other 108 patients had normal findings on
videofluoroscopy.Out of the 92 patients with the abnormal videofluoroscopic
findings,28 patients have pharyngeal retention alone with no other structural
abnormalities.We focussed mainly on the patients with pharyngeal retention.16 of
them were found to have grade 3 severe pharyngeal retention.These patients had
history of stroke in the past.They were given training on swallowing manouveres
to prevent aspiration.We found that these manouveres are effective in doing
so.Another 12 patients had pharyngeal retention with no aspiration risk and they
were in between the 61-80 yrs
Determining the underlying Fermi surface of strongly correlated superconductors
The notion of a Fermi surface (FS) is one of the most ingenious concepts
developed by solid state physicists during the past century. It plays a central
role in our understanding of interacting electron systems. Extraordinary
efforts have been undertaken, both by experiment and by theory, to reveal the
FS of the high temperature superconductors (HTSC), the most prominent strongly
correlated superconductors. Here, we discuss some of the prevalent methods used
to determine the FS and show that they lead generally to erroneous results
close to half filling and at low temperatures, due to the large superconducting
gap (pseudogap) below (above) the superconducting transition temperature. Our
findings provide a perspective on the interplay between strong correlations and
superconductivity and highlight the importance of strong coupling theories for
the characterization as well as the determination of the underlying FS in ARPES
experiments
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