Gaussian Belief with dynamic data and in dynamic network

In this paper we analyse Belief Propagation over a Gaussian model in a dynamic environment. Recently, this has been proposed as a method to average local measurement values by a distributed protocol ("Consensus Propagation", Moallemi & Van Roy, 2006), where the average is available for read-out at every single node. In the case that the underlying network is constant but the values to be averaged fluctuate ("dynamic data"), convergence and accuracy are determined by the spectral properties of an associated Ruelle-Perron-Frobenius operator. For Gaussian models on Erdos-Renyi graphs, numerical computation points to a spectral gap remaining in the large-size limit, implying exceptionally good scalability. In a model where the underlying network also fluctuates ("dynamic network"), averaging is more effective than in the dynamic data case. Altogether, this implies very good performance of these methods in very large systems, and opens a new field of statistical physics of large (and dynamic) information systems.Comment: 5 pages, 7 figure

Plasticity, Permanence, and Patient Performance: Study Design and Data Analysis in the Cognitive Rehabilitation of Acquired Communication Impairments

Communication impairments such as aphasia and apraxia can follow brain injury and result in limitation of an individual's participation in social interactions, and capacity to convey needs and desires. Our research group developed a computerized treatment program which is based on neuroscientific principles of speech production (Whiteside and Varley, 1998; Varley and Whiteside, 2001; Varley, 2010) and has been shown to improve communication in people with apraxia and aphasia (Dyson et al., 2009; Varley et al., 2009). Investigations of treatment efficacy have presented challenges in study design, effect measurement, and statistical analysis which are likely to be shared by other researchers in the wider field of cognitive neurorehabilitation evaluation. Several key factors define neurocognitively based therapies, and differentiate them and their evaluation from other forms of medical intervention. These include: (1) inability to “blind” patients to the content of the treatment and control procedures; (2) neurocognitive changes that are more permanent than pharmacological treatments on which many medical study designs are based; and (3) the semi-permanence of therapeutic effects means that new baselines are set throughout the course of a given treatment study, against which comparative interventions or long term retention effects must be measured. This article examines key issues in study design, effect measurement, and data analysis in relation to the rehabilitation of patients undergoing treatment for apraxia of speech. Results from our research support a case for the use of multiperiod, multiphase cross-over design with specific computational adjustments and statistical considerations. The paper provides researchers in the field with a methodologically feasible and statistically viable alternative to other designs used in rehabilitation sciences

Self-Administered Computer Therapy for Apraxia of Speech

Background and Purpose There is currently little evidence on effective interventions for poststroke apraxia of speech. We report outcomes of a trial of self-administered computer therapy for apraxia of speech. Methods Effects of speech intervention on naming and repetition of treated and untreated words were compared with those of a visuospatial sham program. The study used a parallel-group, 2-period, crossover design, with participants receiving 2 interventions. Fifty participants with chronic and stable apraxia of speech were randomly allocated to 1 of 2 order conditions: speech-first condition versus sham-first condition. Period 1 design was equivalent to a randomized controlled trial. We report results for this period and profile the effect of the period 2 crossover. Results Period 1 results revealed significant improvement in naming and repetition only in the speech-first group. The sham-first group displayed improvement in speech production after speech intervention in period 2. Significant improvement of treated words was found in both naming and repetition, with little generalization to structurally similar and dissimilar untreated words. Speech gains were largely maintained after withdrawal of intervention. There was a significant relationship between treatment dose and response. However, average self-administered dose was modest for both groups. Future software design would benefit from incorporation of social and gaming components to boost motivation. Conclusions Single-word production can be improved in chronic apraxia of speech with behavioral intervention. Self-administered computerized therapy is a promising method for delivering high-intensity speech/language rehabilitation

High-sensitivity troponin I concentrations are a marker of an advanced hypertrophic response and adverse outcomes in patients with aortic stenosis

Aims: High-sensitivity cardiac troponin I (cTnI) assays hold promise in detecting the transition from hypertrophy to heart failure in aortic stenosis. We sought to investigate the mechanism for troponin release in patients with aortic stenosis and whether plasma cTnI concentrations are associated with long-term outcome. Methods and results: Plasma cTnI concentrations were measured in two patient cohorts using a high-sensitivity assay. First, in the Mechanism Cohort, 122 patients with aortic stenosis (median age 71, 67% male, aortic valve area 1.0 ± 0.4 cm2) underwent cardiovascular magnetic resonance and echocardiography to assess left ventricular (LV) myocardial mass, function, and fibrosis. The indexed LV mass and measures of replacement fibrosis (late gadolinium enhancement) were associated with cTnI concentrations independent of age, sex, coronary artery disease, aortic stenosis severity, and diastolic function. In the separate Outcome Cohort, 131 patients originally recruited into the Scottish Aortic Stenosis and Lipid Lowering Trial, Impact of REgression (SALTIRE) study, had long-term follow-up for the occurrence of aortic valve replacement (AVR) and cardiovascular deaths. Over a median follow-up of 10.6 years (1178 patient-years), 24 patients died from a cardiovascular cause and 60 patients had an AVR. Plasma cTnI concentrations were associated with AVR or cardiovascular death HR 1.77 (95% CI, 1.22 to 2.55) independent of age, sex, systolic ejection fraction, and aortic stenosis severity. Conclusions: In patients with aortic stenosis, plasma cTnI concentration is associated with advanced hypertrophy and replacement myocardial fibrosis as well as AVR or cardiovascular death

Hormones and temporal components of speech: sex differences and effects of menstrual cyclicity on speech

Voice onset time (VOT) is a salient acoustic parameter of speech which signals the “voiced” and “voiceless” status of plosives in English (e.g. the initial sound in ‘bat’ vs. the initial sound in ‘pat’). As a micro-temporal acoustic parameter, VOT may be sensitive to changes in hormones which may affect the neuromuscular systems involved in speech production. This study adopted a novel approach by investigating the effects of menstrual cycle phase and sex on VOT. VOT data representing the 6 plosives of English (/p b t d k g/) were examined for 7 women (age 20-23 years) at two phases of the menstrual cycle (day 18-25: High Estrogen and Progesterone; day 2-5: Low Estrogen and Progesterone). Results indicated that menstrual cycle phase had a significant interaction with the identity of the plosive (F (5,30) = 5.869, P .05), or the contrast between voiced and voiceless cognates (F (1,10) = .407, P > .05). In contrast, the high hormone phase VOT samples displayed significant plosive by sex interactions (F (5,50) = 4.442, P < .005). In addition, significant sex differences were found for the contrasts between cognate voiced and voiceless plosives (F (1,10) = 5.019, P < .05); the women displayed a more marked voiced/voiceless contrast. The findings suggest that ovarian hormones play some role in shaping some temporal components of speech

Error reduction therapy in reducing struggle and grope behaviours in apraxia of speech

We report an intervention study focused on the speech production difficulties present in acquired apraxia of speech (AOS). The intervention was a self-administered computer therapy that targeted whole word production and incorporated error reduction strategies. The effectiveness of the therapy was contrasted to that of a visuospatial sham computer program, and performance across treated words, and two sets of matched words, was assessed. Two groups of participants completed the study which employed a two-phase cross-over treatment design. Participants were randomly assigned to a speech first or sham first condition. Treatments were administered for six weeks, with a four week rest between interventions. Participants were assessed five times in total; twice at baseline, once following each of the intervention phases, and once following a lapse of eight weeks after the end of the second phase of intervention. The occurrence of accurate word production and speech characterised by struggle and groping behaviours was recorded on a repetition task. Participants showed significant gains in speech accuracy and fluency, and reductions in articulatory groping and struggle behaviours following the use of the speech program. These gains were largely maintained once the therapy was withdrawn

Cold Bose gases with large scattering lengths

We calculate the energy and condensate fraction for a dense system of bosons interacting through an attractive short range interaction with positive s-wave scattering length $a$. At high densities, $n>>a^{-3}$, the energy per particle, chemical potential, and square of the sound speed are independent of the scattering length and proportional to $n^{2/3}$, as in Fermi systems.Comment: 4 pages, 3 figure

The Relationship Between Apraxia of Speech and Oral Apraxia: Association or Dissociation?

Acquired apraxia of speech (AOS) is a motor speech disorder that affects the implementation of articulatory gestures and the fluency and intelligibility of speech. Oral apraxia (OA) is an impairment of nonspeech volitional movement. Although many speakers with AOS also display difficulties with volitional nonspeech oral movements, the relationship between the 2 conditions is unclear. This study explored the relationship between speech and volitional nonspeech oral movement impairment in a sample of 50 participants with AOS. We examined levels of association and dissociation between speech and OA using a battery of nonspeech oromotor, speech, and auditory/aphasia tasks. There was evidence of a moderate positive association between the 2 impairments across participants. However, individual profiles revealed patterns of dissociation between the 2 in a few cases, with evidence of double dissociation of speech and oral apraxic impairment. We discuss the implications of these relationships for models of oral motor and speech control