38 research outputs found
Density Matrix Renormalisation Group Approach to the Massive Schwinger Model
The massive Schwinger model is studied, using a density matrix
renormalisation group approach to the staggered lattice Hamiltonian version of
the model. Lattice sizes up to 256 sites are calculated, and the estimates in
the continuum limit are almost two orders of magnitude more accurate than
previous calculations. Coleman's picture of `half-asymptotic' particles at
background field theta = pi is confirmed. The predicted phase transition at
finite fermion mass (m/g) is accurately located, and demonstrated to belong in
the 2D Ising universality class.Comment: 38 pages, 18 figures, submitted to PR
A New Finite-lattice study of the Massive Schwinger Model
A new finite lattice calculation of the low lying bound state energies in the
massive Schwinger model is presented, using a Hamiltonian lattice formulation.
The results are compared with recent analytic series calculations in the low
mass limit, and with a new higher order non-relativistic series which we
calculate for the high mass limit. The results are generally in good agreement
with these series predictions, and also with recent calculations by light cone
and related techniques
Annex 19 : predictive model for the dengue incidences in Sri Lanka using mobile network big data
The study constructs a usable predictive model for any given Medical Officer of Health (MOH) division, which is the smallest medical administrative district in Sri Lanka, by taking human mobility into account. It includes the importation of dengue into immunologically ’naive’ regions. Derived mobility values for each region of the country are weighted using reported past dengue cases. The study introduces a generalizable methodology to fuse big data sources with traditional data sources, using machine learning techniques. Mobile Network Big Data (MNBD) consists of data categories such as Call Detail Records (CDR), Internet access usage records, and airtime recharge records
MCL-CAw: A refinement of MCL for detecting yeast complexes from weighted PPI networks by incorporating core-attachment structure
Abstract Background The reconstruction of protein complexes from the physical interactome of organisms serves as a building block towards understanding the higher level organization of the cell. Over the past few years, several independent high-throughput experiments have helped to catalogue enormous amount of physical protein interaction data from organisms such as yeast. However, these individual datasets show lack of correlation with each other and also contain substantial number of false positives (noise). Over these years, several affinity scoring schemes have also been devised to improve the qualities of these datasets. Therefore, the challenge now is to detect meaningful as well as novel complexes from protein interaction (PPI) networks derived by combining datasets from multiple sources and by making use of these affinity scoring schemes. In the attempt towards tackling this challenge, the Markov Clustering algorithm (MCL) has proved to be a popular and reasonably successful method, mainly due to its scalability, robustness, and ability to work on scored (weighted) networks. However, MCL produces many noisy clusters, which either do not match known complexes or have additional proteins that reduce the accuracies of correctly predicted complexes. Results Inspired by recent experimental observations by Gavin and colleagues on the modularity structure in yeast complexes and the distinctive properties of "core" and "attachment" proteins, we develop a core-attachment based refinement method coupled to MCL for reconstruction of yeast complexes from scored (weighted) PPI networks. We combine physical interactions from two recent "pull-down" experiments to generate an unscored PPI network. We then score this network using available affinity scoring schemes to generate multiple scored PPI networks. The evaluation of our method (called MCL-CAw) on these networks shows that: (i) MCL-CAw derives larger number of yeast complexes and with better accuracies than MCL, particularly in the presence of natural noise; (ii) Affinity scoring can effectively reduce the impact of noise on MCL-CAw and thereby improve the quality (precision and recall) of its predicted complexes; (iii) MCL-CAw responds well to most available scoring schemes. We discuss several instances where MCL-CAw was successful in deriving meaningful complexes, and where it missed a few proteins or whole complexes due to affinity scoring of the networks. We compare MCL-CAw with several recent complex detection algorithms on unscored and scored networks, and assess the relative performance of the algorithms on these networks. Further, we study the impact of augmenting physical datasets with computationally inferred interactions for complex detection. Finally, we analyse the essentiality of proteins within predicted complexes to understand a possible correlation between protein essentiality and their ability to form complexes. Conclusions We demonstrate that core-attachment based refinement in MCL-CAw improves the predictions of MCL on yeast PPI networks. We show that affinity scoring improves the performance of MCL-CAw.http://deepblue.lib.umich.edu/bitstream/2027.42/78256/1/1471-2105-11-504.xmlhttp://deepblue.lib.umich.edu/bitstream/2027.42/78256/2/1471-2105-11-504-S1.PDFhttp://deepblue.lib.umich.edu/bitstream/2027.42/78256/3/1471-2105-11-504-S2.ZIPhttp://deepblue.lib.umich.edu/bitstream/2027.42/78256/4/1471-2105-11-504.pdfPeer Reviewe
Hamiltonian Study of Improved Lattice Gauge Theory in Three Dimensions
A comprehensive analysis of the Symanzik improved anisotropic
three-dimensional U(1) lattice gauge theory in the Hamiltonian limit is made.
Monte Carlo techniques are used to obtain numerical results for the static
potential, ratio of the renormalized and bare anisotropies, the string tension,
lowest glueball masses and the mass ratio. Evidence that rotational symmetry is
established more accurately for the Symanzik improved anisotropic action is
presented. The discretization errors in the static potential and the
renormalization of the bare anisotropy are found to be only a few percent
compared to errors of about 20-25% for the unimproved gauge action. Evidence of
scaling in the string tension, antisymmetric mass gap and the mass ratio is
observed in the weak coupling region and the behaviour is tested against
analytic and numerical results obtained in various other Hamiltonian studies of
the theory. We find that more accurate determination of the scaling
coefficients of the string tension and the antisymmetric mass gap has been
achieved, and the agreement with various other Hamiltonian studies of the
theory is excellent. The improved action is found to give faster convergence to
the continuum limit. Very clear evidence is obtained that in the continuum
limit the glueball ratio approaches exactly 2, as expected in a
theory of free, massive bosons.Comment: 13 pages, 15 figures, submitted to Phys. Rev.
An unusual case of spontaneous Mycobacterium chelonae corneal ulcer in a healthy middle-aged adult [Retraction]
Bhandari V, Sriganesh R, Relekar K. An unusual case of spontanous Mycobacterium chelonae corneal ulcer in a healthy middle-aged adult. Int Med Case Rep J. 2016;9:121–124. The Editor-in-Chief and Publisher have retracted this paper because of duplicate publication in Case Reports in Ophthalmological Medicine on June 20, 2015. The retraction relates to this pape
An unusual case of spontaneous Mycobacterium chelonae corneal ulcer in a healthy middle-aged adult
Vipul Bhandari, R Sriganesh, Kirti RelekarDepartment of Cornea, Nethradhama Eye Hospital, Bengaluru, IndiaBackground: To report a rare presentation of culture-positive Mycobacterium chelonae corneal ulcer and its management.Findings: We report a rare case of a patient with a history of chronic pain and blurriness of vision. Examination revealed a chronic nonhealing paracentral corneal ulcer inferiorly at the 5–7 o'clock meridian with anterior chamber reaction unresponsive to routine antibiotic and antifungal medications with Mantoux test positivity in a middle-aged nondiabetic patient with no prior history of trauma, ocular surgery, and contact lens usage. Ziehl–Neelsen staining of the nonhealing ulcer revealed acid-fast bacilli typical of M. chelonae, with subsequent culture positivity in Löwenstein–Jensen medium. Subsequent treatment with topical fortified amikacin and tobramycin resulted in rapid healing of the corneal ulcer.Conclusion: M. chelonae presenting as a chronic nonhealing corneal ulcer spontaneously occurring in a healthy adult with no predisposing factor draws attention towards the need to have a good index of suspicion by performing a Ziehl–Neelsen stain and culture, and subsequent successful management with topical fortified amikacin and tobramycin.Keywords: spontaneous, M. chelonae, nonhealing corneal ulcer, health