12,354 research outputs found
Power Spectrum Estimators For Large CMB Datasets
Forthcoming high-resolution observations of the Cosmic Microwave Background
(CMB) radiation will generate datasets many orders of magnitude larger than
have been obtained to date. The size and complexity of such datasets presents a
very serious challenge to analysing them with existing or anticipated
computers. Here we present an investigation of the currently favored algorithm
for obtaining the power spectrum from a sky-temperature map --- the quadratic
estimator. We show that, whilst improving on direct evaluation of the
likelihood function, current implementations still inherently scale as the
equivalent of the cube of the number of pixels or worse, and demonstrate the
critical importance of choosing the right implementation for a particular
dataset.Comment: 8 pages LATEX, no figures, corrected misaligned columns in table
Motivational, volitional and multiple goal predictors of walking in people with type 2 diabetes
Acknowledgment MNâs PhD scholarship was provided by Ministry of Health and Medical Education (Islamic Republic of Iran). This study was funded by the University of Aberdeen reference number: GP007RGC1618. FFS is funded by Fuse, the UK Clinical Research Collaboration Centre of Excellence for Translational Research in Public Health (grant number: MR/K02325X/1). The researchers gratefully acknowledge all the Type 2 diabetic patients and their household members who participated in the study for their contribution to this study; without them there would be no data. The researchers gratefully acknowledge the SDRN for providing the list of Type 2 diabetes and helping for sampling.Peer reviewedPublisher PD
Excavations at the Viking Barrow Cemetery at Heath Wood, Ingleby, Derbyshire
The cemetery at Heath Wood, Ingleby, Derbyshire, is the only known Scandinavian cremation cemetery in the British Isles. It comprises fifty-nine barrows, of which about one-third have been excavated on previous occasions, although earlier excavators concluded that some were empty cenotaph mounds. From 1998 to 2000 three barrows were examined. Our investigations have suggested that each of the barrows contained a burial, although not all contain evidence of a pyre. A full report of the 1998-2000 excavations is provided, alongside a summary of the earlier finds. The relationship of Heath Wood to the neighbouring site at Repton is examined, in order to understand its significance for the Scandinavian settlement of the Danelaw. It is concluded that Heath Wood may have been a war cemetery of the Viking Great Army of AD 873-8
Gravitational Lensing Effect on the Two-point Correlation of Hotspots in the Cosmic Microwave Background
We investigate the weak gravitational lensing effect due to the large-scale
structure of the universe on two-point correlations of local maxima ({\em
hotspots}) in the 2D sky map of the cosmic microwave background (CMB)
anisotropy. According to the Gaussian random statistics as most inflationary
scenarios predict, the hotspots are discretely distributed with some {\em
characteristic} angular separations on the last scattering surface owing to
oscillations of the CMB angular power spectrum.
The weak lensing then causes pairs of hotspots which are separated with the
characteristic scale to be observed with various separations. We found that the
lensing fairly smoothes the oscillatory features of the two-point correlation
function of hotspots. This indicates that the hotspots correlations can be a
new statistical tool for measuring shape and normalization of the power
spectrum of matter fluctuations from the lensing signatures.Comment: 6 pages, 2 figures; replaced with published versio
Lensing effect on the relative orientation between the Cosmic Microwave Background ellipticities and the distant galaxies
The low redshift structures of the Universe act as lenses in a similar way on
the Cosmic Microwave Background light and on the distant galaxies (say at
redshift about unity). As a consequence, the CMB temperature distortions are
expected to be statistically correlated with the galaxy shear, exhibiting a
non-uniform distribution of the relative angle between the CMB and the galactic
ellipticities. Investigating this effect we find that its amplitude is as high
as a 10% excess of alignement between CMB and the galactic ellipticities
relative to the uniform distribution. The relatively high signal-to-noise ratio
we found should makes possible a detection with the planned CMB data sets,
provided that a galaxy survey follow up can be done on a sufficiently large
area. It would provide a complementary bias-independent constraint on the
cosmological parameters.Comment: 7 pages, 3 figures; uses emulateapj.sty; submitted to Ap
Kinetics of diffusion-limited catalytically-activated reactions: An extension of the Wilemski-Fixman approach
We study kinetics of diffusion-limited catalytically-activated
reactions taking place in three dimensional systems, in which an annihilation
of diffusive particles by diffusive traps may happen only if the
encounter of an with any of the s happens within a special catalytic
subvolumen, these subvolumens being immobile and uniformly distributed within
the reaction bath. Suitably extending the classical approach of Wilemski and
Fixman (G. Wilemski and M. Fixman, J. Chem. Phys. \textbf{58}:4009, 1973) to
such three-molecular diffusion-limited reactions, we calculate analytically an
effective reaction constant and show that it comprises several terms associated
with the residence and joint residence times of Brownian paths in finite
domains. The effective reaction constant exhibits a non-trivial dependence on
the reaction radii, the mean density of catalytic subvolumens and particles'
diffusion coefficients. Finally, we discuss the fluctuation-induced kinetic
behavior in such systems.Comment: To appear in J. Chem. Phy
Cosmic Microwave Background Anisotropy Window Functions Revisited
The primary results of most observations of cosmic microwave background (CMB)
anisotropy are estimates of the angular power spectrum averaged through some
broad band, called band-powers. These estimates are in turn what are used to
produce constraints on cosmological parameters due to all CMB observations.
Essential to this estimation of cosmological parameters is the calculation of
the expected band-power for a given experiment, given a theoretical power
spectrum. Here we derive the "band power" window function which should be used
for this calculation, and point out that it is not equivalent to the window
function used to calculate the variance. This important distinction has been
absent from much of the literature: the variance window function is often used
as the band-power window function. We discuss the validity of this assumed
equivalence, the role of window functions for experiments that constrain the
power in {\it multiple} bands, and summarize a prescription for reporting
experimental results. The analysis methods detailed here are applied in a
companion paper to three years of data from the Medium Scale Anisotropy
Measurement.Comment: 5 pages, 1 included .eps figure, PRD in press---final published
versio
An indoor positioning system using Bluetooth Low Energy
In this paper, we present a Bluetooth Low Energy (BLE) based indoor positioning system developed for monitoring the daily living pattern of old people (e.g. people living with dementia) or individuals with disabilities. The proposed sensing system is composed of multiple sensors that are installed in different locations in a home environment. The specific location of the user in the building has been pre-recorded into the proposed sensing system that captures the raw Received Signal Strength Indicator (RSSI) from the BLE beacon that is attached on the user. Two methods are proposed to determine the indoor location and the tracking of the users: a trilateration-based method and fingerprinting-based method. Experiments have been carried out in different home environments to verify the proposed system and methods. The results show that our system is able to accurately track the user location in home environments and can track the living patterns of the user which, in turn, may be used to infer the health status of the user. Our results also show that the positions of the BLE beacons on the user and different quality of BLE beacons do not affect the tracking accuracy
Strengthening impact assessment: a call for integration and focus
We suggest that the impact assessment community has lost its way based on our observation that impact assessment is under attack because of a perceived lack of efficiency. Specifically, we contend that the proliferation of different impact assessment types creates separate silos of expertise and feeds arguments for not only a lack of efficiency but also a lack of effectiveness of the process through excessive specialisation and a lack of interdisciplinary practice. We propose that the solution is a return to the basics of impact assessment with a call for increased integration around the goal of sustainable development and focus through better scoping. We rehearse and rebut counter arguments covering silo-based expertise, advocacy, democracy, sustainability understanding and communication. We call on the impact assessment community to rise to the challenge of increasing integration and focus, and to engage in the debate about the means of strengthening impact assessment
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