Evolutionary coordination system for fixed-wing communications unmanned aerial vehicles

A system to coordinate the movement of a group of un- manned aerial vehicles that provide a network backbone over mobile ground-based vehicles with communication needs is presented. Using evo- lutionary algorithms, the system evolves flying manoeuvres that position the aerial vehicles by fulfilling two key requirements; i) they maximise net coverage and ii) they minimise the power consumption. Experimental results show that the proposed coordination system is able to offer a de- sirable level of adaptability with respect to the objectives set, providing useful feedback for future research directions

Kinetic theory of age-structured stochastic birth-death processes

Classical age-structured mass-action models such as the McKendrick-von Foerster equation have been extensively studied but are unable to describe stochastic fluctuations or population-size-dependent birth and death rates. Stochastic theories that treat semi-Markov age-dependent processes using, e.g., the Bellman-Harris equation do not resolve a population's age structure and are unable to quantify population-size dependencies. Conversely, current theories that include size-dependent population dynamics (e.g., mathematical models that include carrying capacity such as the logistic equation) cannot be easily extended to take into account age-dependent birth and death rates. In this paper, we present a systematic derivation of a new, fully stochastic kinetic theory for interacting age-structured populations. By defining multiparticle probability density functions, we derive a hierarchy of kinetic equations for the stochastic evolution of an aging population undergoing birth and death. We show that the fully stochastic age-dependent birth-death process precludes factorization of the corresponding probability densities, which then must be solved by using a Bogoliubov-–Born–-Green–-Kirkwood-–Yvon-like hierarchy. Explicit solutions are derived in three limits: no birth, no death, and steady state. These are then compared with their corresponding mean-field results. Our results generalize both deterministic models and existing master equation approaches by providing an intuitive and efficient way to simultaneously model age- and population-dependent stochastic dynamics applicable to the study of demography, stem cell dynamics, and disease evolution

Recombination dramatically speeds up evolution of finite populations

We study the role of recombination, as practiced by genetically-competent bacteria, in speeding up Darwinian evolution. This is done by adding a new process to a previously-studied Markov model of evolution on a smooth fitness landscape; this new process allows alleles to be exchanged with those in the surrounding medium. Our results, both numerical and analytic, indicate that for a wide range of intermediate population sizes, recombination dramatically speeds up the evolutionary advance

Using Meta-Ethnography to Synthesize Relevant Studies: Capturing the Bigger Picture in Dementia with Challenging Behavior within Families

In understanding the range and depth of people’s experiences, it is important to include the wide range of approaches which capture the richness within a given knowledge base. However, systematic reviews using quantitative data alone risk missing findings that can contribute to a better understanding of a research question. In response, meta-ethnography has emerged as a potentially useful method to synthesize and integrate both qualitative and quantitative data from different perspectives using qualitative methodology. In this case study, we describe how we have used meta-ethnography to better understand how families experience dementia. We address a particular issue of selecting the highest quality evidence across a range of epistemologies

Maximum principle and mutation thresholds for four-letter sequence evolution

A four-state mutation-selection model for the evolution of populations of DNA-sequences is investigated with particular interest in the phenomenon of error thresholds. The mutation model considered is the Kimura 3ST mutation scheme, fitness functions, which determine the selection process, come from the permutation-invariant class. Error thresholds can be found for various fitness functions, the phase diagrams are more interesting than for equivalent two-state models. Results for (small) finite sequence lengths are compared with those for infinite sequence length, obtained via a maximum principle that is equivalent to the principle of minimal free energy in physics.Comment: 25 pages, 16 figure

Practitioners’ understanding of barriers to accessing specialist support by family carers of people with dementia in distress

Distressing symptoms in dementia are hard to manage for many family carers. This article explores practitioners' perceptions of the barriers to accessing skilled behaviour management support encountered by carers. A survey of cases referred to the English National Health Service (n = 5,360) was followed by in-depth group discussions and practitioner interviews. Data revealed that practitioners focused on care home residents or older people with mental health problems other than dementia, rather than community-dwelling people with dementia and families. Barriers to access included misperceptions about the nature of distressing behaviour affecting carers and structural limitations in the capacity of specialist services to respond to carers

Feasibility and acceptability evaluation of the Promoting Independence in Dementia (PRIDE) intervention for living well with dementia

OBJECTIVES: Post-diagnostic psychosocial interventions could play an important role in supporting people with mild dementia remain independent. The Promoting Independence in Dementia (PRIDE) intervention was developed to address this. METHOD: The mixed methods non-randomized, pre-post feasibility study occurred across England. Facilitators were recruited from the voluntary sector and memory services. Participants and their supporters took part in the three-session intervention. Outcome measures were collected at baseline and follow-up. To evaluate acceptability, focus groups and interviews were conducted with a subsample of participants and facilitators. RESULTS: Contextual challenges to delivery including national research governance changes, affected recruitment of study sites. Thirty-four dyads consented, with 14 facilitators providing the intervention. Dyads took part in at least two sessions (79%), and 73% in all three. Outcome measures were completed by 79% without difficulty, with minimal missing data. No significant changes were found on pre and post assessments. Post hoc analysis found moderate effect size improvements for self-management (SMAS instrument) in people with dementia (d = 0.41) and quality of life (EQ5D measure) in carers (d = 0.40). Qualitative data indicated that dyads found PRIDE acceptable, as did intervention facilitators. CONCLUSIONS: The three-session intervention was well accepted by participant-dyads and intervention facilitators. A randomized controlled trial of PRIDE would need to carefully consider recruitment potential across geographically varied settings and site stratification according to knowledge of contextual factors, such as the diversity of post-diagnostic services across the country. Letting sites themselves be responsible for identifying suitable intervention facilitators was successful. The self-report measures showed potential to be included in the main trial

The purification and characterization of ATP synthase complexes from the mitochondria of four fungal species.

The ATP synthases have been isolated by affinity chromatography from the mitochondria of the fungal species Yarrowia lipolytica, Pichia pastoris, Pichia angusta and Saccharomyces cerevisiae. The subunit compositions of the purified enzyme complexes depended on the detergent used to solubilize and purify the complex, and the presence or absence of exogenous phospholipids. All four enzymes purified in the presence of n-dodecyl-β-D-maltoside had a complete complement of core subunits involved directly in the synthesis of ATP, but they were deficient to different extents in their supernumerary membrane subunits. In contrast, the enzymes from P. angusta and S. cerevisiae purified in the presence of n-decyl-β-maltose neopentyl glycol and the phospholipids 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine, cardiolipin (diphosphatidylglycerol) and 1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] had a complete complement of core subunits and also contained all of the known supernumerary membrane subunits, e, f, g, j, k and ATP8 (or Aap1), plus an additional new membrane component named subunit l, related in sequence to subunit k. The catalytic domain of the enzyme from P. angusta was more resistant to thermal denaturation than the enzyme from S. cerevisiae, but less stable than the catalytic domain of the bovine enzyme, but the stator and the integrity of the transmembrane proton pathway were most stable in the enzyme from P. angusta. The P. angusta enzyme provides a suitable source of enzyme for studying the structure of the membrane domain and properties associated with that sector of the enzyme complex.This work was funded by the intramural programme of the Medical Research Council (MRC). T.J.C was the recipient of an MRC graduate studentship

Relational experiences of people seeking help and assessment for subjective cognitive concern and memory loss

Objective: To understand the experience of people who seek help for subjective cognitive concern and memory loss, including people not referred for further assessment. To understand the patients’ perspective of the medical process of receiving a cognitive assessment. This work is situated within the context of policy priorities for dementia diagnosis. Methods: Participants with and without dementia were recruited through NHS trusts and community organisations in four regional areas in England. Data were collected using longitudinal qualitative interviews. Transcript data were thematically analysed. Results: Sample of 41 people (mean 75 years, 25 dementia diagnoses). Interpretative thematic analyses focused on the presence or absence of trust in relational experiences. There were three transition points where trust could be specifically developed or undermined: 1) deciding to seek help; 2) healthcare practitioners’ response to help-seeking; 3) process and outcome of assessment. Triggers for help-seeking for subjective cognitive concern were being prompted by family and knowing a relative with dementia. When participants perceived healthcare practitioners’ behaviour as dismissive, they had less trust in the outcome of the healthcare encounter. Misunderstandings and absence of trust in assessment processes led to participants stating they did not fully agree with the outcomes of the assessment. Conclusions: Healthcare practitioners have an important role in supporting people with subjective cognitive concern ensuring patients have trust in assessment outcomes. Where the validity of the assessment process is seen as ambiguous, people can be left dealing with uncertainty, rather than being clear about ways they can manage their condition, situation or status