4,659 research outputs found
Discovery of the Principal Cystic Fibrosis Mutation (F508del) in Ancient DNA from Iron Age Europeans
The most common, life-threatening autosomal recessive disease of Europeans and Euro-Americans, cystic fibrosis (CF), occurs predominately in patients with the F508del mutation.1 Although F508del is currently detectable as a single allele in 1/30-1/40 Europeans2-4 and Euro-Americans,5 it has not been determined what heterozygote selective advantage(s) might account for its relatively high prevalence. Indirect evidence6 suggests that this mutation was present in Brittany at least 3000 years ago, but no direct analyses of ancient DNA have been reported to identify F508del and clarify its frequency in prehistoric inhabitants of Europe. Here we show that F508del was present in 3 of 32 Iron Age inhabitants of Austria from whom DNA could be recovered from molar teeth using procedures that fulfill authenticity criteria.7 Because these individuals, who were buried in cemeteries along the Danube river, were shown by radiocarbon dating of isolated bone collagen to have lived there during 544-255 BC, this indicates that the F508del mutation is definitely more than 2000 years old and that CF (the disease) was present among them. More generally, the apparent enrichment of this Iron Age population in F508del suggests an evolutionary advantage in their environment that can be investigated by interdisciplinary strategies of paleoepidemiology
Geostrophic balance preserving interpolation in mesh adaptive shallow-water ocean modelling
The accurate representation of geostrophic balance is an essential
requirement for numerical modelling of geophysical flows. Significant effort is
often put into the selection of accurate or optimal balance representation by
the discretisation of the fundamental equations. The issue of accurate balance
representation is particularly challenging when applying dynamic mesh
adaptivity, where there is potential for additional imbalance injection when
interpolating to new, optimised meshes.
In the context of shallow-water modelling, we present a new method for
preservation of geostrophic balance when applying dynamic mesh adaptivity. This
approach is based upon interpolation of the Helmholtz decomposition of the
Coriolis acceleration. We apply this in combination with a discretisation for
which states in geostrophic balance are exactly steady solutions of the
linearised equations on an f-plane; this method guarantees that a balanced and
steady flow on a donor mesh remains balanced and steady after interpolation
onto an arbitrary target mesh, to within machine precision. We further
demonstrate the utility of this interpolant for states close to geostrophic
balance, and show that it prevents pollution of the resulting solutions by
imbalanced perturbations introduced by the interpolation
Preventing Repeat Victimization: A Systematic Review
This report presents a systematic review, including a statistical meta-analysis, of the effects of initiatives to prevent repeat victimization
Cyberbullying among adolescents: Measures in search of a construct
Objective: This review focuses on the literature on cyberbullying among adolescents. Currently, there is no unified theoretical framework to move the field of cyberbullying forward. Due to some unique features of cyberbullying, researchers have generally assumed that it is distinct from aggression perpetrated in person. Many measures of cyberbullying have been developed based on this assumption rather than to test competing models and inform a theoretical framework for cyberbullying. Approach: We review current theory and research on cyberbullying within the context of the broader literature on aggression to explore the usefulness of the assumption that cyberbullying represents a distinct form of aggression. Associations between cyberbullying and general forms of aggression and psychosocial predictors of cyberbullying are discussed. Conclusions: Based on the empirical research, we suggest that the media through which aggression is perpetrated may be best conceptualized as a new dimension on which aggression can be classified, rather than cyberbullying as a distinct counterpart to existing forms of aggression. Research on cyberbullying should be considered within the context of theoretical and empirical knowledge of aggression in adolescence. Using this approach will create a theoretical framework for understanding cyberbullying, focus future research, and guide prevention efforts
Processes and priorities in planning mathematics teaching
Insights into teachers' planning of mathematics reported here were gathered as part of a broader project examining aspects of the implementation of the Australian curriculum in mathematics (and English). In particular, the responses of primary and secondary teachers to a survey of various aspects of decisions that inform their use of curriculum documents and assessment processes to plan their teaching are discussed. Teachers appear to have a clear idea of the overall topic as the focus of their planning, but they are less clear when asked to articulate the important ideas in that topic. While there is considerable diversity in the processes that teachers use for planning and in the ways that assessment information informs that planning, a consistent theme was that teachers make active decisions at all stages in the planning process. Teachers use a variety of assessment data in various ways, but these are not typically data extracted from external assessments. This research has important implications for those responsible for supporting teachers in the transition to the Australian Curriculum: Mathematic
Distributive Justice and the Crime Drop
Data were extracted from a total of almost 600000 respondents from all sweeps of the Crime Survey for England and Wales (CSEW) 1982-2012 to determine whether victimisation was more or less concentrated across households during the crime drop. The most victimised household decile experienced the greatest absolute decline in victimisation but still accounted for over 70% of all victimisations suffered. Methodological issues underlying the patterns observed are discussed. The characteristics associated with highly victimised household are consistent across survey sweeps. Cross-national and crime type extension of work of the kind undertaken is advocated as both intrinsically important and likely to clarify the dynamics of the crime drop
On the MIMO Capacity with Multiple Linear Transmit Covariance Constraints
This paper presents an efficient approach to computing the capacity of multiple-input multiple-output (MIMO) channels under multiple linear transmit covariance constraints (LTCCs). LTCCs are general enough to include several special types of power constraints as special cases such as the sum power constraint (SPC), per-antenna power constraint (PAPC), or a combination thereof. Despite its importance and generality, most of the existing literature considers either SPC or PAPC independently. Efficient solutions to the computation of the MIMO capacity with a combination of SPC and PAPC have been recently reported, but were only dedicated to multipleinput single-output (MISO) systems. For the general case of LTCCs, we propose a low-complexity semi-closed-form approach tothecomputationoftheMIMOcapacity.Specifically,amodified minimax duality is first invoked to transform the considered problem in the broadcast channel into an equivalent minimax problem in the dual multiple access channel. Then alternating optimization and concave-convex procedure are utilized to derive water-filling-based algorithms to find a saddle point of the minimax problem. This is different from the state-of-the-art solutions to the considered problem, which are based on interiorpoint or subgradient methods. Analytical and numerical results are provided to demonstrate the effectiveness of the proposed low-complexity solution under various MIMO scenarios
Assessment of Adolescents’ Victimization, Aggression, and Problem Behaviors: Evaluation of the Problem Behavior Frequency Scale
This study evaluated the Problem Behavior Frequency Scale (PBFS), a self-report measure designed to assess adolescents’ frequency of victimization, aggression, and other problem behaviors. Analyses were conducted on a sample of 5,532 adolescents from 37 schools at 4 sites. About half (49%) of participants were male; 48% self-identified as Black non-Hispanic; 21% as Hispanic, 18% as White non-Hispanic. Adolescents completed the PBFS and measures of beliefs and values related to aggression, and delinquent peer associations at the start of the 6th grade and over 2 years later. Ratings of participants’ behavior were also obtained from teachers on the Behavioral Assessment System for Children. Confirmatory factor analyses supported a 7-factor model that differentiated among 3 forms of aggression (physical, verbal, and relational), 2 forms of victimization (overt and relational), drug use, and other delinquent behavior. Support was found for strong measurement invariance across gender, sites, and time. The PBFS factors generally showed the expected pattern of correlations with teacher ratings of adolescents’ behavior and self-report measures of relevant constructs
An Efficient Precoder Design for Multiuser MIMO Cognitive Radio Networks with Interference Constraints
We consider a linear precoder design for an underlay cognitive radio
multiple-input multiple-output broadcast channel, where the secondary system
consisting of a secondary base-station (BS) and a group of secondary users
(SUs) is allowed to share the same spectrum with the primary system. All the
transceivers are equipped with multiple antennas, each of which has its own
maximum power constraint. Assuming zero-forcing method to eliminate the
multiuser interference, we study the sum rate maximization problem for the
secondary system subject to both per-antenna power constraints at the secondary
BS and the interference power constraints at the primary users. The problem of
interest differs from the ones studied previously that often assumed a sum
power constraint and/or single antenna employed at either both the primary and
secondary receivers or the primary receivers. To develop an efficient numerical
algorithm, we first invoke the rank relaxation method to transform the
considered problem into a convex-concave problem based on a downlink-uplink
result. We then propose a barrier interior-point method to solve the resulting
saddle point problem. In particular, in each iteration of the proposed method
we find the Newton step by solving a system of discrete-time Sylvester
equations, which help reduce the complexity significantly, compared to the
conventional method. Simulation results are provided to demonstrate fast
convergence and effectiveness of the proposed algorithm.Comment: Accepted to appear in IEEE Trans. Vehicular Technology, 13 pages, 8
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Multi-disciplinary perspectives: application of the Consolidated Framework for Implementation Research to evaluate a health coaching initiative
Long term conditions are a leading cause of mortality and morbidity. Their management is founded on a combination of approaches involving government policy, better integration between health and care systems, and individual responsibility for self-care. Health coaching has emerged as an approach to encouraging individual responsibility and enhancing the self-management of long term conditions. This paper focuses on the evaluation of a workforce initiative in a diverse and socially deprived community. The initiative sought both to improve integration between health and care services for people with long term conditions, and equip practitioners with health coaching skills. The aim of the study was to contribute an empirical understanding of what practitioners perceive to be the contextual factors that impact on the adoption of health coaching in community settings. These factors were conceptualised using the Consolidated Framework for Implementation Research (CFIR). A stratified purposive sample of 22 health and care practitioners took part in semi-structured telephone interviews. Data were analysed using the CFIR as an analytical framework. The perceptions of trainees mapped onto the major domains of the CFIR: characteristics of the intervention, outer setting, inner setting, characteristics of individuals involved, and process of implementation. Individual patient expectations, co-morbidities and social context were central to the extent to which practitioners and patients engaged with health coaching. Structural constraints within provider services and the wider NHS were also reported as discouraging initiatives that focused on long term rewards rather than short term wins. The authors recommend further research is undertaken both to understand the role of health coaching in disadvantaged communities and ensure the service user voice is heard
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