Degree of explanation

Partial explanations are everywhere. That is, explanations citing causes that explain some but not all of an effect are ubiquitous across science, and these in turn rely on the notion of degree of explanation. I argue that current accounts are seriously deficient. In particular, they do not incorporate adequately the way in which a cause’s explanatory importance varies with choice of explanandum. Using influential recent contrastive theories, I develop quantitative definitions that remedy this lacuna, and relate it to existing measures of degree of causation. Among other things, this reveals the precise role here of chance, as well as bearing on the relation between causal explanation and causation itself

It's just a feeling: why economic models do not explain

Julian Reiss correctly identified a trilemma about economic models: we cannot maintain that they are false, but nevertheless explain and that only true accounts explain. In this reply we give reasons to reject the second premise – that economic models explain. Intuitions to the contrary should be distrusted

The visual orbits of the spectroscopic binaries HD 6118 and HD 27483 from the Palomar Testbed Interferometer

We present optical interferometric observations of two double-lined spectroscopic binaries, HD 6118 and HD 27483, taken with the Palomar Testbed Interferometer (PTI) in the K band. HD 6118 is one of the most eccentric spectroscopic binaries and HD 27483 a spectroscopic binary in the Hyades open cluster. The data collected with PTI in 2001-2002 allow us to determine astrometric orbits and when combined with the radial velocity measurements derive all physical parameters of the systems. The masses of the components are 2.65 +/- 0.27 M_Sun and 2.36 +/- 0.24 M_Sun for HD 6118 and 1.38 +/- 0.13 M_Sun and 1.39 +/- 0.13 M_Sun for HD 27483. The apparent semi-major axis of HD 27483 is only 1.2 mas making it the closest binary successfully observed with an optical interferometer.Comment: submitted to Ap

“Living with aphasia the best way I can”: a feasibility study exploring solution focused brief therapy for people with aphasia

Objective: Post-stroke aphasia can profoundly affect a person’s social and emotional well-being. This study explored the feasibility of solution focused brief therapy as an accessible intervention, and investigated its impact on participants’ psychosocial well-being. Participants and methods: Small-scale repeated measures feasibility study. Participants received between three and five therapy sessions. They were assessed on psychosocial outcome measures pre and post therapy, and took part in post-therapy in-depth qualitative interviews. Three men and two women with chronic aphasia took part; age range 40s to 70s. Results: Participants found the therapy acceptable and it was possible to adapt the approach so as to be communicatively accessible. Quantitative assessments showed encouraging trends in improved mood: pre-therapy GHQ-12 mean (SD): 4.80 (4.60), median: 6; post therapy mean (SD): 2.00 (2.55), median: 1; and improved communicative participation: pre-therapy CPIB mean (SD): 7.80 (5.76), median: 7; post therapy mean (SD): 12.20 (4.44), median: 14. Measures of social network and connectedness, however, remained stable. Themes emerging from the qualitative analysis included changes to mood, communicative participation, mobility and everyday activities. Conclusions: This small-scale study suggests solution focused brief therapy is a promising approach in helping people with aphasia build positive change in their lives

“Struggling to stay connected”: comparing the social relationships of healthy older people and people with stroke and aphasia

Background: Having a stroke and aphasia can profoundly affect a person’s social relationships. Further, poor social support is associated with adverse post-stroke outcomes such as psychological distress, worse quality of life, and worse recovery. To date, no study has used complex measures of social network and perceived social support to compare stroke survivors with aphasia, without aphasia, and the general older population. A better understanding of which aspects of social support are most affected by stroke and aphasia may inform stroke services. Aims: To compare the social networks and perceived functional social support of people following a stroke, with and without aphasia, and healthy older adults. Methods & Procedures: Cross-sectional interview-based study. People with a first stroke were recruited from two acute stroke units and interviewed 6 months post onset. We recruited 60 stroke participants without aphasia, average age 69.8 (SD = 14.3), and 11 stroke participants with aphasia, average age 66.5 (SD = 13.7). One hundred and six healthy older adults were recruited via the community, average age 62.8 (SD = 9.5). All participants completed the Medical Outcomes Study Social Support Survey (SSS) and the Stroke Social Network Scale (SSNS). One-way independent groups ANOVAs were used to compare stroke participants with aphasia, stroke participants without aphasia, and healthy older adults. Outcomes & Results: After adjusting for multiple comparisons (p < .004), there was a significant difference on overall social network between the three groups (p < .001), with those with aphasia scoring significantly lower than healthy older adults (p < .001). The difference between healthy older adults and people with aphasia on the friends domain of the social network scale was also significant (p = .002). There was no significant difference between the three groups on overall perceived functional social support. Conclusions: People with aphasia have less diverse social networks than healthy older adults, with friendships particularly affected. Stroke services should monitor for social isolation, and consider ways to support people following a stroke in maintaining or establishing diverse social networks

ANALYSIS OF NUCLEI FLUORESCENCE HISTOGRAMS USING NON-LINEAR FUNCTIONS OR WAVELETS

Histograms based on 5,000 nuclei from cells (Chinese hamster ovary cells, bone marrow cells) are used to determine the coefficient of variation (CV) of observations surrounding the highest peak. The cells are subjected to various treatments, for example exposure to herbicides. By eyeballing the histogram, an interval under the highest peak is determined. The CV calculated from the histogram on the eyeballed interval is the response variable in an ANOVA. To avoid the subjectivity of eyeballing the histogram, non-linear functions such as the Gaussian density function can be used to model the histogram. The CV may then be determined from the parameter estimates. In many experiments nonlinear functions modeling the histograms smooth away differences in CV s obtained this way, though visually the histograms appear to be different. Then nonlinear functions or wavelets can be used to obtain intervals for calculating CV s of the histograms restricted to these intervals. The nonlinear models require close initial values for each histogram, while the wavelets just require choice of wavelet and level of decomposition

Adjustment with aphasia after stroke: study protocol for a pilot feasibility randomised controlled trial for SUpporting wellbeing through PEeR Befriending (SUPERB)

Background: Despite the high prevalence of mood problems after stroke, evidence on effective interventions particularly for those with aphasia is limited. There is a pressing need to systematically evaluate interventions aiming to improve wellbeing for people with stroke and aphasia. This study aims to evaluate the feasibility of a peer-befriending intervention. Methods/design: SUPERB is a single blind, parallel group feasibility trial of peer befriending for people with aphasia post-stroke and low levels of psychological distress. The trial includes a nested qualitative study and pilot economic evaluation and it compares usual care (n = 30) with usual care + peer befriending (n = 30). Feasibility outcomes include proportion screened who meet criteria, proportion who consent, rate of consent, number of missing/incomplete data on outcome measures, attrition rate at follow-up, potential value of conducting main trial using value of information analysis (economic evaluation), description of usual care, and treatment fidelity of peer befriending. Assessments and outcome measures (mood, wellbeing, communication, and social participation) for participants and significant others will be administered at baseline, with outcome measures re-administered at 4 and 10 months post-randomisation. Peer befrienders will complete outcome measures before training and after they have completed two cycles of befriending. The qualitative study will use semi-structured interviews of purposively sampled participants (n = 20) and significant others (n = 10) from both arms of the trial, and all peer befrienders to explore the acceptability of procedures and experiences of care. The pilot economic evaluation will utilise the European Quality of life measure (EQ-5D-5 L) and a stroke-adapted version of the Client Service Receipt Inventory (CSRI). Discussion: This study will provide information on feasibility outcomes and an initial indication of whether peer befriending is a suitable intervention to explore further in a definitive phase III randomised controlled trial. Trial registration: ClinicalTrials.gov identifier NCT02947776, registered 28th October 2016

SOlution Focused brief therapy In post-stroke Aphasia (SOFIA Trial): protocol for a feasibility randomised controlled trial

Background: Around a quarter of people post stroke will experience aphasia, a language disability. Having aphasia places someone at risk of becoming depressed and isolated. There is limited evidence for effective interventions to enhance psychological well-being for this client group. A potential intervention is Solution Focused Brief Therapy (SFBT), which supports a person to build meaningful, achievable change through focusing on a person’s skills and resources rather than their deficits. The SOFIA Trial aims to explore the acceptability of SFBT to people with varying presentations of aphasia, including severe aphasia, and to assess the feasibility of conducting a future definitive trial investigating clinical and cost effectiveness. Methods: The trial is a single-blind, randomised, wait-list controlled feasibility trial with nested qualitative research and pilot economic evaluation comparing SFBT plus usual care to usual care alone. The study will recruit 32 participants with aphasia who are ≥6 months post stroke. All participants will be assessed on psychosocial outcome measures at baseline, then at three and six months post randomisation by assessors blinded to treatment allocation. Participants will be randomly assigned to intervention group (start intervention immediately post randomisation) or wait-list group (start intervention six months post randomisation). Wait-list group will additionally be assessed nine months post randomisation. The intervention consists of up to six SFBT sessions delivered over three months by speech and language therapists. Participants and therapists will also take part in in-depth interviews exploring their experiences of the study. The pilot economic evaluation will use the EQ-5D-5L measure and an adapted Client Service Receipt Inventory. People with aphasia have been involved in designing and monitoring the trial. Discussion: Given the high levels of depression and isolation, there is a need to investigate effective interventions that enhance the psychological wellbeing of people with aphasia. Trial registration: ClinicalTrials.gov NCT03245060. 10/08/2017

Deterministically Computing Reduction Numbers of Polynomial Ideals

We discuss the problem of determining reduction number of a polynomial ideal I in n variables. We present two algorithms based on parametric computations. The first one determines the absolute reduction number of I and requires computation in a polynomial ring with (n-dim(I))dim(I) parameters and n-dim(I) variables. The second one computes via a Grobner system the set of all reduction numbers of the ideal I and thus in particular also its big reduction number. However,it requires computations in a ring with n.dim(I) parameters and n variables.Comment: This new version replaces the earlier version arXiv:1404.1721 and it has been accepted for publication in the proceedings of CASC 2014, Warsaw, Polna