8,675 research outputs found
Reconstruction of Gravitational Lensing Using WMAP 7-Year Data
Gravitational lensing by large scale structure introduces non-Gaussianity
into the Cosmic Microwave Background and imprints a new observable, which can
be used as a cosmological probe. We apply a four-point estimator to the
Wilkinson Microwave Anisotropy Probe (WMAP) 7-year coadded temperature maps
alone to reconstruct the gravitational lensing signal. The Gaussian bias is
simulated and subtracted, and the higher order bias is investigated. We measure
a gravitational lensing signal with a statistical amplitude of =
using all the correlations of the W- and V-band Differencing
Assemblies (DAs). We therefore conclude that WMAP 7-year data alone, can not
detect lensing.Comment: 10 pages, 10 figure
Rigid Object Tracking Algorithms for Low-Cost AR Devices
Augmented reality (AR) applications rely on robust and efficient methods for tracking. Tracking methods use a computer-internal representation of the object to track, which can be either sparse or dense representations. Sparse representations use only a limited set of feature points to represent an object to track, whereas dense representations almost mimic the shape of an object. While algorithms performed on sparse representations are faster, dense representations can distinguish multiple objects. The research presented in this paper investigates the feasibility of a dense tracking method for rigid object tracking, which incorporates the both object identification and object tracking steps. We adopted a tracking method that has been developed for the Microsoft Kinect to support single object tracking. The paper describes this method and presents the results. We also compared two different methods for mesh reconstruction in this algorithm. Since meshes are more informative when identifying a rigid object, this comparison indicates which algorithm shows the best performance for this task and guides our future research efforts
Measuring gravitational lensing of the cosmic microwave background using cross correlation with large scale structure
We cross correlate the gravitational lensing map extracted from cosmic
microwave background measurements by the Wilkinson Microwave Anisotropy Probe
(WMAP) with the radio galaxy distribution from the NRAO VLA Sky Survey (NVSS)
by using a quadratic estimator technique. We use the full covariance matrix to
filter the data, and calculate the cross-power spectra for the lensing-galaxy
correlation. We explore the impact of changing the values of cosmological
parameters on the lensing reconstruction, and obtain statistical detection
significances at . The results of all cross correlations pass the
curl null test as well as a complementary diagnostic test using the NVSS data
in equatorial coordinates. We forecast the potential for Planck and NVSS to
constrain the lensing-galaxy cross correlation as well as the galaxy bias. The
lensing-galaxy cross-power spectra are found to be Gaussian distributed.Comment: 16 pages, 10 figure
Eccrine porocarcinoma of the lower extremity: A case report and review of literature
Eccrine porocarcinoma is a rare malignancy of the eccrine sweat gland. It is usually found frequently on the lower extremities, and it affects both sexes equally usually in the sixth to seventh decade. In our case, we present a 42-year-old male patient with a recurring exophytic tumor on the right lower extremity without local extension. The initial tumor was biopsied, excised and diagnosed as an eccrine poroma. The tumor then recurred 6 years later, was re-excised, reconstructed with a soleus muscle flap and diagnosed as an eccrine porocarcinoma
How will mass-vaccination change COVID-19 lockdown requirements in Australia?
To prevent future outbreaks of COVID-19, Australia is pursuing a
mass-vaccination approach in which a targeted group of the population
comprising healthcare workers, aged-care residents and other individuals at
increased risk of exposure will receive a highly effective priority vaccine.
The rest of the population will instead have access to a less effective
vaccine. We apply a large-scale agent-based model of COVID-19 in Australia to
investigate the possible implications of this hybrid approach to
mass-vaccination. The model is calibrated to recent epidemiological and
demographic data available in Australia, and accounts for several components of
vaccine efficacy. Within a feasible range of vaccine efficacy values, our model
supports the assertion that complete herd immunity due to vaccination is not
likely in the Australian context. For realistic scenarios in which herd
immunity is not achieved, we simulate the effects of mass-vaccination on
epidemic growth rate, and investigate the requirements of lockdown measures
applied to curb subsequent outbreaks. In our simulations, Australia's
vaccination strategy can feasibly reduce required lockdown intensity and
initial epidemic growth rate by 43\% and 52\%, respectively. The severity of
epidemics, as measured by the peak number of daily new cases, decreases by up
to two orders of magnitude under plausible mass-vaccination and lockdown
strategies. The study presents a strong argument for a large-scale vaccination
campaign, which would significantly reduce the intensity of non-pharmaceutical
interventions in Australia and curb future outbreaks
Transforming growth factor-β1 and diabetic nephropathy
Transforming growth factor-β1 (TGF-β1) is established to be involved in the pathogenesis of diabetic nephropathy. The diabetic milieu enhances oxidative stress and induces the expression of TGF-β1. TGF-β1 promotes cell hypertrophy and extracellular matrix accumulation in the mesangium, which decreases glomerular filtration rate and leads to chronic renal failure. Recently, TGF-β1 has been demonstrated to regulate urinary albumin excretion by both increasing glomerular permeability and decreasing reabsorption in the proximal tubules. TGF-β1 also increases urinary excretion of water, electrolytes and glucose by suppressing tubular reabsorption in both normal and diabetic conditions. Although TGF-β1 exerts hypertrophic and fibrogenic effects in diabetic nephropathy, whether suppression of the function of TGF-β1 can be an option to prevent or treat the complication is still controversial. This is partly because adrenal production of mineralocorticoids could be augmented by the suppression of TGF-β1. However, differentiating the molecular mechanisms for glomerulosclerosis from those for the suppression of the effects of mineralocorticoids by TGF-β1 may assist in developing novel therapeutic strategies for diabetic nephropathy. In this review, we discuss recent findings on the role of TGF-β1 in diabetic nephropathy
The influence of the mass-ratio on the acceleration of particles by filamentation instabilities
Almost all sources of high energy particles and photons are associated with
jet phenomena. Prominent sources of such highly relativistic outflows are
pulsar winds and Active Galactic Nuclei. The current understanding of these
jets assumes diluted plasmas which are best described as kinetic phenomena. In
this kinetic description particle acceleration to ultra-relativistic speeds can
occur in completely unmagnetized and neutral plasmas through insetting effects
of instabilities. Even though the morphology and nature of particle spectra are
understood to a certain extent, the composition of the jets is not known yet.
While Poynting-flux dominated jets are certainly composed of electron-positron
plasmas, the understanding of the governing physics in AGN jets is mostly
unclear. In this article we investigate how the constituting elements of an
electron-positron-proton plasma behave differently under the variation of the
fundamental mass-ratio m_p/m_e. We studied initially unmagnetized
counterstreaming plasmas using fully relativistic three-dimensional
particle-in-cell simulations to investigate the influence of the mass-ratio on
particle acceleration and magnetic field generation in electron-positron-proton
plasmas. We covered a range of mass-ratios m_p/m_e between 1 and 100 with a
particle number composition of n_{p^+}/n_{e^+} of 1 in one stream, only protons
are injected in the other, whereas electrons are present in both to guarantee
charge neutrality in the simulation box. We find that with increasing proton
mass the instability takes longer to develop and for mass-ratios > 20 the
particles seem to be accelerated in two phases which can be accounted to the
individual instabilities of the different species. This means that for high
mass ratios the coupling between electrons/positrons and the heavier protons,
which occurs in low mass-ratios, disappears.Comment: 15 pages, 6 figure
Spatial distributions in static heavy-light mesons: a comparison of quark models with lattice QCD
Lattice measurements of spatial distributions of the light quark bilinear
densities in static mesons allow to test directly and in detail the wave
functions of quark models. These distributions are gauge invariant quantities
directly related to the spatial distribution of wave functions. We make a
detailed comparison of the recent lattice QCD results with our own quark
models, formulated previously for quite different purposes. We find a striking
agreement not only between our two quark models, but also with the lattice QCD
data for the ground state in an important range of distances up to about 4/GeV.
Moreover the agreement extends to the L=1 states [j^P=(1/2)^+]. An explanation
of several particular features completely at odds with the non-relativistic
approximation is provided. A rather direct, somewhat unexpected and of course
approximate relation between wave functions of certain quark models and QCD has
been established.Comment: 40 pages, 5 figures (version published in PRD
Bimodal Distribution of Area-Weighted Latitude of Sunspots And Solar North-South Asymmetry
We study the latitudinal distribution of sunspots observed from 1874 to 2009
using the center-of-latitude (COL). We calculate COL by taking the
area-weighted mean latitude of sunspots for each calendar month. We then form
the latitudinal distribution of COL for the sunspots appearing in the northern
and southern hemispheres separately, and in both hemispheres with unsigned and
signed latitudes, respectively. We repeat the analysis with subsets which are
divided based on the criterion of which hemisphere is dominant for a given
solar cycle. Our primary findings are as follows: (1) COL is not monotonically
decreasing with time in each cycle. Small humps can be seen (or short plateaus)
around every solar maxima. (2) The distribution of COL resulting from each
hemisphere is bimodal, which can well be represented by the double Gaussian
function. (3) As far as the primary component of the double Gaussian function
is concerned, for a given data subset, the distributions due to the sunspots
appearing in two different hemispheres are alike. Regardless of which
hemisphere is magnetically dominant, the primary component of the double
Gaussian function seems relatively unchanged. (4) When the northern (southern)
hemisphere is dominant the width of the secondary component of the double
Gaussian function in the northern (southern) hemisphere case is about twice as
wide as that in the southern (northern) hemisphere. (5) For the distribution of
the COL averaged with signed latitude, whose distribution is basically
described by a single Gaussian function, it is shifted to the positive
(negative) side when the northern (southern) hemisphere is dominant. Finally,
we conclude by briefly discussing the implications of these findings on the
variations in the solar activity.Comment: Accepted for publication in New Astronom
A new xinjiangchelyid turtle from the Middle Jurassic of Xinjiang, China and the evolution of the basipterygoid process in Mesozoic turtles
Background: Most turtles from the Middle and Late Jurassic of Asia are referred to the newly defined clade Xinjiangchelyidae, a group of mostly shell-based, generalized, small to mid-sized aquatic froms that are widely considered to represent the stem lineage of Cryptodira. Xinjiangchelyids provide us with great insights into the plesiomorphic anatomy of crown-cryptodires, the most diverse group of living turtles, and they are particularly relevant for understanding the origin and early divergence of the primary clades of extant turtles. Results: Exceptionally complete new xinjiangchelyid material from the ?Qigu Formation of the Turpan Basin (Xinjiang Autonomous Province, China) provides new insights into the anatomy of this group and is assigned to Xinjiangchelys wusu n. sp. A phylogenetic analysis places Xinjiangchelys wusu n. sp. in a monophyletic polytomy with other xinjiangchelyids, including Xinjiangchelys junggarensis, X. radiplicatoides, X. levensis and X. latiens. However, the analysis supports the unorthodox, though tentative placement of xinjiangchelyids and sinemydids outside of crown-group Testudines. A particularly interesting new observation is that the skull of this xinjiangchelyid retains such primitive features as a reduced interpterygoid vacuity and basipterygoid processes. Conclusions: The homology of basipterygoid processes is confidently demonstrated based on a comprehensive review of the basicranial anatomy of Mesozoic turtles and a new nomenclatural system is introduced for the carotid canal system of turtles. The loss of the basipterygoid process and the bony enclosure of the carotid circulation system occurred a number of times independently during turtle evolution suggesting that the reinforcement of the basicranial region was essential for developing a rigid skull, thus paralleling the evolution of other amniote groups with massive skulls. © 2013 Rabi et al.; licensee BioMed Central Ltd
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