3,609 research outputs found
Negative Differential Mobility in Interacting Particle Systems
Driven particles in presence of crowded environment, obstacles or kinetic
constraints often exhibit negative differential mobility (NDM) due to their
decreased dynamical activity. We propose a new mechanism for complex
many-particle systems where slowing down of certain {\it non-driven} degrees of
freedom by the external field can give rise to NDM. This phenomenon, resulting
from inter-particle interactions, is illustrated in a pedagogical example of
two interacting random walkers, one of which is biased by an external field
while the same field only slows down the other keeping it unbiased. We also
introduce and solve exactly the steady state of several driven diffusive
systems, including a two species exclusion model, asymmetric misanthrope and
zero-range processes, to show explicitly that this mechanism indeed leads to
NDM.Comment: 5 pages, 3 figure
On the Real Spectra of Calogero Model with Complex Coupling
We study the eigenvalue problem of the rational Calogero model with the
coupling of the inverse-square interaction as a complex number. We show that
although this model is manifestly non-invariant under the combined parity and
time-reversal symmetry , the eigenstates corresponding to the zero
value of the generalized angular momentum have real energies.Comment: revtex4 8 pages, 2 figure
Analysis of Dielectric Loss in a Helix Slow-wave Structure
Equivalent circuit analysis of a helix slow-wave structure was carried out and closed form expressions were derived for the shunt capacitance and shunt conductance per unit length of the transmission-line equivalent circuit of the structure. These equivalent circuit parameters were interpreted for the dielectric attenuation constant of the slow-wave structure. The analysis was computationally simple and showsed excellent agreement with published results. The analysis was furthered for predicting the dielectric loss in typical C-Ku band and Ka band helical slow-wave structures, and variation of dielectric loss with temperature.Defence Science Journal, 2009, 59(5), pp.549-552, DOI:http://dx.doi.org/10.14429/dsj.59.155
A Bibliometric Overview of the Field of Type-2 Fuzzy Sets and Systems [Discussion Forum]
© 2005-2012 IEEE. Fuzzy Sets and Systems is an area of computational intelligence, pioneered by Lotfi Zadeh over 50 years ago in a seminal paper in Information and Control. Fuzzy Sets (FSs) deal with uncertainty in our knowledge of a particular situation. Research and applications in FSs have grown steadily over 50 years. More recently, we have seen a growth in Type-2 Fuzzy Set (T2 FS) related papers, where T2 FSs are utilized to handle uncertainty in realworld problems. In this paper, we have used bibliometric methods to obtain a broad overview of the area of T2 FSs. This method analyzes information on the bibliographic details of published journal papers, which includes title, authors, author address, journals and citations, extracted from the Science and Social Science Citation Indices in the Web of Science (WoS) database for the last 20 years (1997-2017). We have compared the growth of publications in the field of FSs, and its subset T2 FSs, identified highly cited papers in T2 FSs, highly cited authors, key institutions, and main countries with researchers involved in T2 FS related research
Novel Quantum States of the Rational Calogero Models Without the Confining Interaction
We show that the N-particle A_{N-1} and B_N rational Calogero models without
the harmonic interaction admit a new class of bound and scattering states.
These states owe their existence to the self-adjoint extensions of the
corresponding Hamiltonians, labelled by a real parameter z. It is shown that
the new states appear for all values of N and for specific ranges of the
coupling constants. Moreover, they are shown to exist even in the excited
sectors of the Calogero models. The self-adjoint extension generically breaks
the classical scaling symmetry, leading to quantum mechanical scaling anomaly.
The scaling symmetry can however be restored for certain values of the
parameter z. We also generalize these results for many particle systems with
classically scale invariant long range interactions in arbitrary dimensions.Comment: Latex file, 21 pages; minor changes in text, some references added,
to appear in Nucl. Phys.
A semi-analytical approach to perturbations in mutated hilltop inflation
We study cosmological perturbations and observational aspects for mutated
hilltop model of inflation. Employing mostly analytical treatment, we evaluate
observable parameters during inflation as well as post-inflationary
perturbations. This further leads to exploring observational aspects related to
Cosmic Microwave Background (CMB) radiation. This semi-analytical treatment
reduces complications related to numerical computation to some extent for
studying the different phenomena related to CMB angular power spectrum for
mutated hilltop inflation.Comment: 7 pages, 2 figures. Improved version to appear in IJMP
Retrospective analysis of random and systematic errors in radiation therapy of head and neck cancer patients and its clinical predictive implications with VMAT treatment
Background: The accuracy of radiotherapy is based on the matching of 2D portal/CBCT image with a reference image. The aim of this study is to determine the random and systematic setup errors (in cm) in radiotherapy of head and neck cancer patients and to derive the setup margin and its clinical implications.Methods: Author retrospectively reviewed the records of 25 head and neck cancer (HNC) patients treated with radiotherapy between Dec 2017 and July 2018. After immobilization, setup accuracy was assessed by registration of XVI image with planning reference image using Elekta XVI image guidance system and the isocenter correction was applied. For each patient 10 CBCT image sets were taken. The translational errors in X, Y and Z directions were used to estimate systematic (Σ) and random (σ) errors and to derive the final setup margin by using van Herk’s formula (2.5Σ + 0.7σ).Results: The mean translational errors ranges from -0.23 cm to 0.32 cm in Lateral (X), -0.15 to 0.16 cm in Longitudinal (Y) and -0.11 to 0.17 cm in vertical (Z) directions. The Mean and SD for systematic errors 0.21±0.13, 0.11±0.18, 0.14±0.11 and random error (in cm) are -0.03±0.33, 0.00±0.21 and 0.05±0.30 in X, Y and Z axis respectively. The final total margin for CTV to PTV including setup margin in the X, Y and Z directions (in cm) were 0.56, 0.61, and 0.47 respectively.Conclusion: Thus, the precise immobilization techniques are very important to reduce the setup margins, and the number of CBCTs during head and neck radiotherapy treatment
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