37,996 research outputs found
The 3XMM/SDSS Stripe 82 Galaxy Cluster Survey: Cluster catalogue and discovery of two merging cluster candidates
We present a galaxy cluster survey based on XMM-Newton observations that are
located in Stripe 82 of the Sloan Digital Sky Survey (SDSS). The survey covers
an area of 11.25 deg. The X-ray cluster candidates were selected as
serendipitously extended detected sources from the third XMM-Newton
serendipitous source catalogue (3XMM-DR5). A cross-correlation of the candidate
list that comprises 94 objects with recently published X-ray and optically
selected cluster catalogues provided optical confirmations and redshift
estimates for about half of the candidate sample. We present a catalogue of
X-ray cluster candidates previously known in X-ray and/or optical bands from
the matched catalogues or NED. The catalogue consists of 54 systems with
redshift measurements in the range of 0.05-1.19 with a median of 0.36. Of
these, 45 clusters have spectroscopic confirmations as stated in the matched
catalogues. We spectroscopically confirmed another 6 clusters from the
available spectroscopic redshifts in the SDSS-DR12. The cluster catalogue
includes 17 newly X-ray discovered clusters, while the remainder were detected
in previous XMM-Newton and/or ROSAT cluster surveys. Based on the available
redshifts and fluxes given in the 3XMM-DR5 catalogue, we estimated the X-ray
luminosities and masses for the cluster sample. We also present the list of the
remaining X-ray cluster candidates (40 objects) that have no redshift
information yet in the literature. Of these candidates, 25 sources are
considered as distant cluster candidates beyond a redshift of 0.6. We also
searched for galaxy cluster mergers in our cluster sample and found two strong
candidates for newly discovered cluster mergers at redshifts of 0.11 and 0.26.
The X-ray and optical properties of these systems are presented.Comment: 17 pages, 12 figures, accepted for publication in A&A, revised
version after language editin
Majorana Neutrinos and Same-Sign Dilepton Production at LHC and in Rare Meson Decays
We discuss same-sign dilepton production mediated by Majorana neutrinos in
high-energy proton-proton collisions pp\ra \ell^+ \ell^{\prime +}X for
at the LHC energy TeV, and
in the rare decays of , , , and mesons of the type M^{+}\ra
M^{\prime -}\ell ^{+}\ell ^{\prime+}. For the reaction, assuming one
heavy Majorana neutrino of mass , we present discovery limits in the
plane where are the mixing
parameters. Taking into account the present limits from low energy experiments,
we show that at LHC for the nominal luminosity L=100 fb there is no room
for observable same-sign dilepton signals. However, increasing the integrated
luminosity by a factor 30, one will have sensitivity to heavy Majorana
neutrinos up to a mass TeV only in the dilepton channels
and , but other dilepton states will not be detectable due to the
already existing strong constraints. We work out a large number of rare meson
decays, both for the light and heavy Majorana neutrino scenarios, and argue
that the present experimental bounds on the branching ratios are too weak to
set reasonable limits on the effective Majorana masses.Comment: 18 pages, 4 figures (requires graphicx), a coefficient in Eq. (4)
corrected leading to drastic reduction in the Majorana-induced same-sign
dilepton cross-section at LHC; revised Figs. 2 and 3; references adde
The Elements of the Neutrino Mass Matrix: Allowed Ranges and Implications of Texture Zeros
We study the range of the elements of the neutrino mass matrix m_nu in the
charged lepton basis. Neutrino-less double beta decay is sensitive to the ee
element of m_nu. We then analyze the phenomenological implications of single
texture zeros. In particular, interesting predictions for the effective mass
can be obtained, in the sense that typically only little cancellation due to
the Majorana phases is expected. Some cases imply constraints on the
atmospheric neutrino mixing angle.Comment: 21 pages, 7 figures. Minor corrections, matches version in PR
Linear Relationship Statistics in Diffusion Limited Aggregation
We show that various surface parameters in two-dimensional diffusion limited
aggregation (DLA) grow linearly with the number of particles. We find the ratio
of the average length of the perimeter and the accessible perimeter of a DLA
cluster together with its external perimeters to the cluster size, and define a
microscopic schematic procedure for attachment of an incident new particle to
the cluster. We measure the fractal dimension of the red sites (i.e., the sites
upon cutting each of them splits the cluster) equal to that of the DLA cluster.
It is also shown that the average number of the dead sites and the average
number of the red sites have linear relationships with the cluster size.Comment: 4 pages, 5 figure
Perceived barriers to physical activity in Type 2 Diabetes Mellitus (T2DM) patients during COVID-19 pandemic in the UAE
Physical activity plays a vital role in the prevention and treatment of Type2 Diabetes Mellitus (T2DM) (Hayes and Kriska, 2008). During the COVID-19 pandemic, physical activity is shown to be imperative in helping support a strong immune system (Chastin et al., 2021) and patients with COVID-19 who have been consistently physically inactive have a significantly higher risk of severe outcomes than patients who were doing some activity (Sallis et al., 2021). Therefore, the objective of this qualitative study was to evaluate the sufferer’s perception of physical inactivity and its social determinants among people with diabetes. Interviews were conducted with 14 participants with diabetes aged 40-60 years old living in the UAE in June-July 2021. The barriers of physical activity were explored through in-depth, semi-structured, audio-taped interviews. Barriers for physical inactivity were grouped around five themes: (1)Life-altering COVID-19: the pandemic that changed the world (2)Social and cultural norms: Islamic faith and family are the two most important influences among Arabs (3)Fatigue: prolonged sitting (due to long commute and sedentary jobs) and in some participants post-viral fatigue syndrome due to COVID-19 infection (4)Fear of illness: due to hyperthermia and comorbidities (5)Impact of lockdown. The prevalence of physical inactivity is high among Arabs. Weather restrictions and cultural obligations may lead to reduction in physical activity levels. Therefore, meeting physical activity guidelines can reduce the risk for severe COVID-19 outcomes among infected adults and is likely to prevent increases in diabetes incidence in this population
Nonlinear Realization of the Local Conform-Affine Symmetry Group for Gravity in the Composite Fiber Bundle Formalism
A gauge theory of gravity based on a nonlinear realization (NLR) of the local
Conform-Affine (CA) group of symmetry transformations is presented. The coframe
fields and gauge connections of the theory are obtained. The tetrads and
Lorentz group metric are used to induce a spacetime metric. The inhomogenously
transforming (under the Lorentz group) connection coefficients serve as
gravitational gauge potentials used to define covariant derivatives
accommodating minimal coupling of matter and gauge fields. On the other hand,
the tensor valued connection forms serve as auxillary dynamical fields
associated with the dilation, special conformal and deformational (shear)
degrees of freedom inherent in the bundle manifold. The bundle curvature of the
theory is determined. Boundary topological invariants are constructed. They
serve as a prototype (source free) gravitational Lagrangian. The Bianchi
identities, covariant field equations and gauge currents are obtained.Comment: 24 pages. to appear in IJGMM
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