255 research outputs found
Revisiting glueball wave functions at zero and finite temperature
We study the sizes and thermal properties of glueballs in a three dimensional
compact Abelian gauge model on improved lattice. We predict the radii of and in the units of string tension, or and fm, for the scalar and tensor glueballs, respectively. We perform a well
controlled extrapolation of the radii to the continuum limit and observe that
our results agree with the predicted values. Using Monte Carlo simulations, we
extract the pole-mass of the lowest scalar and tensor glueballs from the
temporal correlators at finite temperature. We see a clear evidence of the
deconfined phase, and the transition appears to be similar to that of the
two-dimensional XY model as expected from universality arguments. Our results
show no significant changes in the glueball wave functions and masses in the
deconfined phase.Comment: 8 pages, 10 figure
Those wonderful elastic waves
We consider in a simple and general way elastic waves in isotropic and
anisotropic media, their polarization, speeds, reflection from interfaces with
mode conversion, and surface waves. Reflection of quasi transverse waves in
anisotropic media from a free surface is shown to be characterized by three
critical angles.Comment: 11 Figures 26 page
Efficient Security and Authentication for Edge-Based Internet of Medical Things
Internet of Medical Things (IoMT)-driven smart health and emotional care is revolutionizing the healthcare industry by embracing several technologies related to multimodal physiological data collection, communication, intelligent automation, and efficient manufacturing. The authentication and secure exchange of electronic health records (EHRs), comprising of patient data collected using wearable sensors and laboratory investigations, is of paramount importance. In this article, we present a novel high payload and reversible EHR embedding framework to secure the patient information successfully and authenticate the received content. The proposed approach is based on novel left data mapping (LDM), pixel repetition method (PRM), RC4 encryption, and checksum computation. The input image of size is upscaled by using PRM that guarantees reversibility with lesser computational complexity. The binary secret data are encrypted using the RC4 encryption algorithm and then the encrypted data are grouped into 3-bit chunks and converted into decimal equivalents. Before embedding, these decimal digits are encoded by LDM. To embed the shifted data, the cover image is divided into blocks and then in each block, two digits are embedded into the counter diagonal pixels. For tamper detection and localization, a checksum digit computed from the block is embedded into one of the main diagonal pixels. A fragile logo is embedded into the cover images in addition to EHR to facilitate early tamper detection. The average peak signal to noise ratio (PSNR) of the stego-images obtained is 41.95 dB for a very high embedding capacity of 2.25 bits per pixel. Furthermore, the embedding time is less than 0.2 s. Experimental results reveal that our approach outperforms many state-of-the-art techniques in terms of payload, imperceptibility, computational complexity, and capability to detect and localize tamper. All the attributes affirm that the proposed scheme is a potential candidate for providing better security and authentication solutions for IoMT-based smart health
Small-Scale Fluctuations in Cosmic X-ray Background : A Power Spectrum Approach
Equations to investigate fluctuations in cosmic X-ray background radiation
due to point-like sources at high-redshift are formulated in a systematic way.
The angular power spectrum of X-ray background fluctuations is investigated
from large-scales to small-scales in various cosmological models such as open
universe models and models with the cosmological constant, assuming a simple
evolution model of the sources. The effect of epoch-dependent bias is
demonstrated for small-angle fluctuations. The contribution from shot noise
fluctuations is also discussed.Comment: 12 pages, 4 figures, Phys.Rev.D in pres
Nonlinear Diffusion Through Large Complex Networks Containing Regular Subgraphs
Transport through generalized trees is considered. Trees contain the simple
nodes and supernodes, either well-structured regular subgraphs or those with
many triangles. We observe a superdiffusion for the highly connected nodes
while it is Brownian for the rest of the nodes. Transport within a supernode is
affected by the finite size effects vanishing as For the even
dimensions of space, , the finite size effects break down the
perturbation theory at small scales and can be regularized by using the
heat-kernel expansion.Comment: 21 pages, 2 figures include
Lowest-lying Tetra-Quark Hadrons in Anisotropic Lattice QCD
We present a detailed study of lowest-lying hadrons in
quenched improved anisotropic lattice QCD. Using the and
diquark-antidiquark local and smeared operators, we attempt to isolate the
signal for and states in two flavour
QCD. In the chiral limit of light-quark mass region, the lowest scalar
state is found to have a mass, MeV, which is slightly
lower than the experimentally observed . The results from our
variational analysis do not indicate a signature of a tetraquark resonance in
I=1 and I=2 channels. After the chiral extrapolation the lowest
state is found to have a mass, MeV. We analysed the
static potential extracted form a tetraquark Wilson loop and illustrated
the behaviour of the state as a bound state, unbinding at some critical
diquark separation. From our analysis we conclude that scalar system
appears as a two-pion scattering state and that there is no spatially-localised
state in the light-quark mass region.Comment: 9 pages, 10 figure
The Hamiltonian limit of (3+1)D SU(3) lattice gauge theory on anisotropic lattices
The extreme anisotropic limit of Euclidean SU(3) lattice gauge theory is
examined to extract the Hamiltonian limit, using standard path integral Monte
Carlo (PIMC) methods. We examine the mean plaquette and string tension and
compare them to results obtained within the Hamiltonian framework of Kogut and
Susskind. The results are a significant improvement upon previous Hamiltonian
estimates, despite the extrapolation procedure necessary to extract
observables. We conclude that the PIMC method is a reliable method of obtaining
results for the Hamiltonian version of the theory. Our results also clearly
demonstrate the universality between the Hamiltonian and Euclidean formulations
of lattice gauge theory. It is particularly important to take into account the
renormalization of both the anisotropy, and the Euclidean coupling ,
in obtaining these results.Comment: 10 pages, 11 figure
Galaxies Discovered Behind the Milky Way by the Dwingeloo Obscured Galaxies Survey
Our Galaxy blocks a significant portion of the extragalactic sky from view,
hampering studies of large-scale structure. This produces an incomplete
knowledge of the distribution of galaxies, and, assuming galaxies trace mass,
of the gravity field. Further, just one unrecognized, nearby massive galaxy
could have large influence over the Milky Way's motion with respect to the
Cosmic Microwave Background. Diligent surveys in the optical and infrared
wavebands can find galaxies through moderate Galactic gas and dust, but close
to the Galactic Plane, only radio surveys are effective. The entire northern
Zone of Avoidance is being searched at 21 cm for galaxies using the Dwingeloo
25-m telescope. A shallow search for nearby, and/or massive galaxies has been
completed, yielding five objects. Two of these galaxies were previously
unknown, and although they are not likely members of the Local Group, are part
of the nearby Universe. A deeper search continues, which will produce a
flux-limited catalog of hidden galaxies. This portion of the survey is
one-third complete, and has detected about 40 objects to date. Based on present
understanding of the HI mass function, the complete survey should uncover 50 -
100 galaxies.Comment: Accepted for publication in Astron. Journal, Tex-file plus 5
postscript figure
Constraints on the Clustering, Biasing and Redshift Distribution of Radio Sources
We discuss how different theoretical predictions for the variance
of the distribution of radio sources can be matched to measurements from the
FIRST survey at different flux limits. The predictions are given by the
integration of models for the angular correlation function for
three different functional forms of the redshift distribution , different
spatial correlation functions and by different evolutions of the bias
with redshift. We also consider the two cases of open and flat Universes.
Although the predicted show substantial differences due to
differences in the 's, these differences are not significant compared to
the uncertainties in the current observations. It turns out that the best fit
is provided by models with constant biasing at all times, although the
difference between models with epoch-independent bias and models with bias that
evolves linearly with redshift is not very large. All models with strong
evolution of bias with epoch are ruled out. As a further step we directly
calculated at 3mJy from the catalogue and matched it with our
models for the angular correlation function in the hypothesis that the
clustering signal comes from two different populations, namely AGN-powered
sources and starbursting galaxies. The results are consistent with a scenario
for hierarchical clustering where the fainter starbursting galaxies trace the
mass at all epochs, while brighter AGN's are strongly biased, with
evolving linearly with redshift, as suggested by some theories of galaxy
formation and evolution.Comment: 14 pages, 12 figures, version to appear on MNRA
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