1,149 research outputs found
Iterative destriping and photometric calibration for Planck-HFI, polarized, multi-detector map-making
We present an iterative scheme designed to recover calibrated I, Q, and U
maps from Planck-HFI data using the orbital dipole due to the satellite motion
with respect to the Solar System frame. It combines a map reconstruction, based
on a destriping technique, juxtaposed with an absolute calibration algorithm.
We evaluate systematic and statistical uncertainties incurred during both these
steps with the help of realistic, Planck-like simulations containing CMB,
foreground components and instrumental noise, and assess the accuracy of the
sky map reconstruction by considering the maps of the residuals and their
spectra. In particular, we discuss destriping residuals for polarization
sensitive detectors similar to those of Planck-HFI under different noise
hypotheses and show that these residuals are negligible (for intensity maps) or
smaller than the white noise level (for Q and U Stokes maps), for l > 50. We
also demonstrate that the combined level of residuals of this scheme remains
comparable to those of the destriping-only case except at very low l where
residuals from the calibration appear. For all the considered noise hypotheses,
the relative calibration precision is on the order of a few 10e-4, with a
systematic bias of the same order of magnitude.Comment: 18 pages, 21 figures. Match published versio
Integrating Lethal and Nonlethal Approaches for Management of Suburban Deer
Evaluations of white-tailed deer (Odocoileus virginianus) population management in suburban landscapes has included debate over lethal control (e.g., sharp-shooting and hunting). These management techniques are often stymied by political impediments, safety concerns, and public attitudes. We are implementing the novel use of surgical sterilization in combination with hunting to mitigate deer-related impacts on Cornell University lands near Ithaca, New York. The project lands are composed of 2 zones: a suburban core campus area (446 ha) and adjacent outlying areas that contain agricultural fields and natural areas where deer hunting is permitted (582 ha). Surgical sterilization will be the primary technique used to reduce deer abundance and associated impacts in the core campus zone. Population reduction in the hunting zone will focus on increased harvest of female deer. During 2007 to 2009, project staff sterilized 58 female deer; 39 adult does were marked with radio transmitters to monitor movement and survival. Ten additional control deer have been captured and radio-collared for a comparison of fawning rates and survival. Hunters harvested 69 deer in the first hunting season (Fall 2008). In spring 2009, infrared-triggered cameras (IRCs) were used to estimate deer abundance in the sterilization zone, which resulted in a density of 21 deer/km2 (56 deer per square mile). In the hunting zone, deer populations will be monitored using a deer sighting log and by data collected at a mandatory deer check station. In both zones, ongoing deer browse and deer-vehicle accident (OVA) studies will ascertain changes in deer impacts throughout the study. Our goal is to determine if deer fertility control integrated with a controlled hunting program on adjacent lands can maximize the efficiency of both techniques. If this integrated management program is successful, it may have additional applications in other communities in New York State and the Northeast
Map-making in small field modulated CMB polarisation experiments: approximating the maximum-likelihood method
Map-making presents a significant computational challenge to the next
generation of kilopixel CMB polarisation experiments. Years worth of time
ordered data (TOD) from thousands of detectors will need to be compressed into
maps of the T, Q and U Stokes parameters. Fundamental to the science goal of
these experiments, the observation of B-modes, is the ability to control noise
and systematics. In this paper, we consider an alternative to the
maximum-likelihood method, called destriping, where the noise is modelled as a
set of discrete offset functions and then subtracted from the time-stream. We
compare our destriping code (Descart: the DEStriping CARTographer) to a full
maximum-likelihood map-maker, applying them to 200 Monte-Carlo simulations of
time-ordered data from a ground based, partial-sky polarisation modulation
experiment. In these simulations, the noise is dominated by either detector or
atmospheric 1/f noise. Using prior information of the power spectrum of this
noise, we produce destriped maps of T, Q and U which are negligibly different
from optimal. The method does not filter the signal or bias the E or B-mode
power spectra. Depending on the length of the destriping baseline, the method
delivers between 5 and 22 times improvement in computation time over the
maximum-likelihood algorithm. We find that, for the specific case of single
detector maps, it is essential to destripe the atmospheric 1/f in order to
detect B-modes, even though the Q and U signals are modulated by a half-wave
plate spinning at 5-Hz.Comment: 18 pages, 17 figures, MNRAS accepted v2: content added (inc: table
2), typos correcte
Embracing virtual outpatient clinics in the era of COVID-19
The response to the COVID-19 pandemic has raised the profile and level of interest in the use, acceptability, safety and effectiveness of virtual outpatient consultations and telemedicine. These models of care are not new but a number of challenges have so far hindered widespread take up and endorsement of these ways of working. With the response to the COVID-19 pandemic, remote and virtual working and consultation have become the default. This paper explores our experience of and learning from virtual and remote consultation and questions how this experience can be retained and developed for the future
Quadratic Lagrangians and Topology in Gauge Theory Gravity
We consider topological contributions to the action integral in a gauge
theory formulation of gravity. Two topological invariants are found and are
shown to arise from the scalar and pseudoscalar parts of a single integral.
Neither of these action integrals contribute to the classical field equations.
An identity is found for the invariants that is valid for non-symmetric Riemann
tensors, generalizing the usual GR expression for the topological invariants.
The link with Yang-Mills instantons in Euclidean gravity is also explored. Ten
independent quadratic terms are constructed from the Riemann tensor, and the
topological invariants reduce these to eight possible independent terms for a
quadratic Lagrangian. The resulting field equations for the parity
non-violating terms are presented. Our derivations of these results are
considerably simpler that those found in the literature
Fast and precise map-making for massively multi-detector CMB experiments
Future cosmic microwave background (CMB) polarisation experiments aim to
measure an unprecedentedly small signal - the primordial gravity wave component
of the polarisation field B-mode. To achieve this, they will analyse huge
datasets, involving years worth of time-ordered data (TOD) from massively
multi-detector focal planes. This creates the need for fast and precise methods
to complement the M-L approach in analysis pipelines. In this paper, we
investigate fast map-making methods as applied to long duration, massively
multi-detector, ground-based experiments, in the context of the search for
B-modes. We focus on two alternative map-making approaches: destriping and TOD
filtering, comparing their performance on simulated multi-detector polarisation
data. We have written an optimised, parallel destriping code, the DEStriping
CARTographer DESCART, that is generalised for massive focal planes, including
the potential effect of cross-correlated TOD 1/f noise. We also determine the
scaling of computing time for destriping as applied to a simulated full-season
data-set for a realistic experiment. We find that destriping can out-perform
filtering in estimating both the large-scale E and B-mode angular power
spectra. In particular, filtering can produce significant spurious B-mode power
via EB mixing. Whilst this can be removed, it contributes to the variance of
B-mode bandpower estimates at scales near the primordial B-mode peak. For the
experimental configuration we simulate, this has an effect on the possible
detection significance for primordial B-modes. Destriping is a viable
alternative fast method to the full M-L approach that does not cause the
problems associated with filtering, and is flexible enough to fit into both M-L
and Monte-Carlo pseudo-Cl pipelines.Comment: 16 pages, 14 figures. MNRAS accepted. Typos corrected and computing
time/memory requirement orders-of-magnitude numbers in section 4 replaced by
precise number
Fast Pixel Space Convolution for CMB Surveys with Asymmetric Beams and Complex Scan Strategies: FEBeCoP
Precise measurement of the angular power spectrum of the Cosmic Microwave
Background (CMB) temperature and polarization anisotropy can tightly constrain
many cosmological models and parameters. However, accurate measurements can
only be realized in practice provided all major systematic effects have been
taken into account. Beam asymmetry, coupled with the scan strategy, is a major
source of systematic error in scanning CMB experiments such as Planck, the
focus of our current interest. We envision Monte Carlo methods to rigorously
study and account for the systematic effect of beams in CMB analysis. Toward
that goal, we have developed a fast pixel space convolution method that can
simulate sky maps observed by a scanning instrument, taking into account real
beam shapes and scan strategy. The essence is to pre-compute the "effective
beams" using a computer code, "Fast Effective Beam Convolution in Pixel space"
(FEBeCoP), that we have developed for the Planck mission. The code computes
effective beams given the focal plane beam characteristics of the Planck
instrument and the full history of actual satellite pointing, and performs very
fast convolution of sky signals using the effective beams. In this paper, we
describe the algorithm and the computational scheme that has been implemented.
We also outline a few applications of the effective beams in the precision
analysis of Planck data, for characterizing the CMB anisotropy and for
detecting and measuring properties of point sources.Comment: 26 pages, 15 figures. New subsection on beam/PSF statistics, new and
better figures, more explicit algebra for polarized beams, added explanatory
text at many places following referees comments [Accepted for publication in
ApJS
Recommended from our members
A mixed methods systematic review on the effects of arts interventions for children and young people at-risk of offending, or who have offended on behavioural, psychosocial, cognitive and offending outcomes: A systematic review
Background
Young people who enter the justice system experience complex health and social needs, and offending behaviour is increasingly recognised as a public health problem. Arts interventions can be used with the aim of preventing or reducing offending or reoffending.
Objectives
1. To evaluate evidence on the effectiveness and impact of arts interventions on keeping children and young people safe from involvement in violence and crime. 2. To explore factors impacting the implementation of arts interventions, and barriers and facilitators to participation and achievement of intended outcomes. 3. To develop a logic model of the processes by which arts interventions might work in preventing offending behaviours.
Search Methods
We searched AMED, Academic Search Complete; APA PsycInfo; CINAHL Plus; ERIC; SocIndex; SportDiscus, Medline, CENTRAL, Web of Science, Scopus, PTSDPubs and Performing Arts Periodicals Database, Sage, the US National Criminal Justice Reference Service, the Global Policing and British Library EThOS databases, and the National Police Library from inception to January 2023 without language restrictions.
Selection Criteria
We included randomised and non-randomised controlled trials and quasi-experimental study designs. We included qualitative studies conducted alongside intervention trials investigating experiences and perceptions of participants, and offering insight into the barriers and facilitators to delivering and receiving arts interventions. We included qualitative and mixed methods studies focused on delivery of arts interventions. We included studies from any global setting. We included studies with CYP (8–25 years) who were identified as at-risk of offending behaviour (secondary populations) or already in the criminal justice system (tertiary populations). We included studies of interventions involving arts participation as an intervention on its own or alongside other interventions. Primary outcomes were: (i) offending behaviour and (ii) anti-pro-social behaviours. Secondary outcomes were: participation/attendance at arts interventions, educational attainment, school attendance and engagement and exclusions, workplace engagement, wellbeing, costs and associated economic outcomes and adverse events.
Data Collection and Analysis
We included 43 studies (3 quantitative, 38 qualitative and 2 mixed methods). We used standard methodological procedures expected by The Campbell Collaboration. We used GRADE and GRADE CERQual to assess the certainty of and confidence in the evidence for quantitative and qualitative data respectively.
Main Results
We found insufficient evidence from quantitative studies to support or refute the effectiveness of arts interventions for CYP at-risk of or who have offended for any outcome. Qualitative evidence suggested that arts interventions may lead to positive emotions, the development of a sense of self, successful engagement in creative practices, and development of positive personal relationships. Arts interventions may need accessible and flexible delivery and are likely to be engaging if they have support from staff, family and community members, are delivered by professional artists, involve culturally relevant activity, a youth focus, regularity and a sustainable strategy. We found limited evidence that a lack of advocacy, low funding, insufficient wider support from key personnel in adjacent services could act as barriers to success. Methodological limitations resulted in a judgement of very low confidence in these findings.
Authors' Conclusions
We found insufficient evidence from quantitative studies to support or refute the effectiveness of arts interventions for CYP at-risk of offending or who have offended for any outcome. We report very low confidence about the evidence for understanding the processes influencing the successful design and delivery of arts interventions in this population of CYP and their impact on behavioural, psychosocial, cognitive and offending outcomes.Brunel University London Information Services, UK | Youth Endowment Foundation, UK | Arts Council England, U
- …