Equilibrium Distribution of Mutators in the Single Fitness Peak Model

This paper develops an analytically tractable model for determining the equilibrium distribution of mismatch repair deficient strains in unicellular populations. The approach is based on the single fitness peak (SFP) model, which has been used in Eigen's quasispecies equations in order to understand various aspects of evolutionary dynamics. As with the quasispecies model, our model for mutator-nonmutator equilibrium undergoes a phase transition in the limit of infinite sequence length. This "repair catastrophe" occurs at a critical repair error probability of $\epsilon_r = L_{via}/L$, where $L_{via}$ denotes the length of the genome controlling viability, while $L$ denotes the overall length of the genome. The repair catastrophe therefore occurs when the repair error probability exceeds the fraction of deleterious mutations. Our model also gives a quantitative estimate for the equilibrium fraction of mutators in {\it Escherichia coli}.Comment: 4 pages, 2 figures (included as separate PS files

Technical Note: Phantom study to evaluate the dose and image quality effects of a computed tomography Organ-based Tube Current Modulation Technique

Purpose This technical note quantifies the dose and image quality performance of a clinically available organ-dose-based tube current modulation (ODM) technique, using experimental and simulation phantom studies. The investigated ODM implementation reduces the tube current for the anterior source positions, without increasing current for posterior positions, although such an approach was also evaluated for comparison. Methods Axial CT scans at 120 kV were performed on head and chest phantoms on an ODM-equipped scanner (Optima CT660, GE Healthcare, Chalfont St. Giles, England). Dosimeters quantified dose to breast, lung, heart, spine, eye lens, and brain regions for ODM and 3D-modulation (SmartmA) settings. Monte Carlo simulations, validated with experimental data, were performed on 28 voxelized head phantoms and 10 chest phantoms to quantify organ dose and noise standard deviation. The dose and noise effects of increasing the posterior tube current were also investigated. Results ODM reduced the dose for all experimental dosimeters with respect to SmartmA, with average dose reductions across dosimeters of 31% (breast), 21% (lung), 24% (heart), 6% (spine), 19% (eye lens), and 11% (brain), with similar results for the simulation validation study. In the phantom library study, the average dose reduction across all phantoms was 34% (breast), 20% (lung), 8% (spine), 20% (eye lens), and 8% (brain). ODM increased the noise standard deviation in reconstructed images by 6%–20%, with generally greater noise increases in anterior regions. Increasing the posterior tube current provided similar dose reduction as ODM for breast and eye lens, increased dose to the spine, with noise effects ranging from 2% noise reduction to 16% noise increase. At noise equal to SmartmA, ODM increased the estimated effective dose by 4% and 8% for chest and head scans, respectively. Increasing the posterior tube current further increased the effective dose by 15% (chest) and 18% (head) relative to SmartmA. Conclusions ODM reduced dose in all experimental and simulation studies over a range of phantoms, while increasing noise. The results suggest a net dose/noise benefit for breast and eye lens for all studied phantoms, negligible lung dose effects for two phantoms, increased lung dose and/or noise for eight phantoms, and increased dose and/or noise for brain and spine for all studied phantoms compared to the reference protocol

Characterization of grain boundaries in silicon

Zero-bias conductance and capacitance measurements at various temperatures were used to study trapped charges and potential barrier height at the boundaries. Deep-level transient spectroscopy (DLTS) was applied to measure the density of states at the boundary. A study of photoconductivity of grain boundaries in p-type silicon demonstrated the applicability of the technique in the measurement of minority carrier recombination velocity at the grain boundary. Enhanced diffusion of phosphorus at grain boundaries in three cast polycrystalline photovoltaic materials was studied. Enhancements for the three were the same, indicating that the properties of boundaries are similar, although grown by different techniques. Grain boundaries capable of enhancing the diffusion were found always to have strong recombination activities; the phenomena could be related to dangling bonds at the boundaries. Evidence that incoherent second-order twins of (111)/(115) type are diffusion-active is presented

Fusing creativity: Cultural metacognition and teamwork in multicultural teams

This study elaborates theoretically and tests empirically a model linking fusion teamwork to creativity in multicultural teams (Janssens & Brett, 2006). The study also introduces cultural metacognition, a dimension of cultural intelligence (Earley & Ang, 2003), as an antecedent of fusion teamwork and creativity. Data were from 246 members of 37 multicultural teams. Results generated from a multilevel modeling analysis were consistent with hypotheses: Across teams, when team members were more highly culturally metacognitive, fusion teamwork and creativity were more likely. All analyses were controlled for generalized affect toward the team to reduce threats to validity of common method bias and affect. The results suggest the value of fusion teamwork for generating creativity in multicultural teams and the importance of having members of multicultural teams who have high versus low levels of cultural metacognition. © 2012 International Association for Conflict Management and Wiley Periodicals, Inc

A systematic review and meta-analysis comparing carer focused and dyadic multicomponent interventions for cares of people with dementia

CC BY-NCObjective: The aim of this study was to compare the efficacy of two approaches: multicomponent interventions that focus on working with the carer and dyadic interventions that work with both the carer and the person with dementia. Method: A systematic review involving a search of Medline, EMBASE, and PsycINFO in October 2015 was performed. Randomized controlled trials involving carers of people with dementia and comparing multicomponent interventions with usual care were included. Results: Pooling of all studies demonstrated that multicomponent interventions can reduce depressive symptoms, improve quality of life, reduce carer impact, and reduce behavioral and psychological symptoms of dementia as well as caregiver upset with these symptoms. We were unable to find a significant difference in the effects of dyadic interventions in comparison with carer focused interventions for these outcomes. Discussion: Although effect sizes associated with intervention are small, multicomponent interventions are relatively inexpensive to deliver, acceptable, and widely applicable

CT Automated Exposure Control Using A Generalized Detectability Index

Purpose Identifying an appropriate tube current setting can be challenging when using iterative reconstruction due to the varying relationship between spatial resolution, contrast, noise, and dose across different algorithms. This study developed and investigated the application of a generalized detectability index (d\u27gen) to determine the noise parameter to input to existing automated exposure control (AEC) systems to provide consistent image quality (IQ) across different reconstruction approaches. Methods This study proposes a task‐based automated exposure control (AEC) method using a generalized detectability index (d\u27gen). The proposed method leverages existing AEC methods that are based on a prescribed noise level. The generalized d\u27gen metric is calculated using lookup tables of task‐based modulation transfer function (MTF) and noise power spectrum (NPS). To generate the lookup tables, the American College of Radiology CT accreditation phantom was scanned on a multidetector CT scanner (Revolution CT, GE Healthcare) at 120 kV and tube current varied manually from 20 to 240 mAs. Images were reconstructed using a reference reconstruction algorithm and four levels of an in‐house iterative reconstruction algorithm with different regularization strengths (IR1–IR4). The task‐based MTF and NPS were estimated from the measured images to create lookup tables of scaling factors that convert between d\u27gen and noise standard deviation. The performance of the proposed d\u27gen‐AEC method in providing a desired IQ level over a range of iterative reconstruction algorithms was evaluated using the American College of Radiology (ACR) phantom with elliptical shell and using a human reader evaluation on anthropomorphic phantom images. Results The study of the ACR phantom with elliptical shell demonstrated reasonable agreement between the d\u27gen predicted by the lookup table and d\u27 measured in the images, with a mean absolute error of 15% across all dose levels and maximum error of 45% at the lowest dose level with the elliptical shell. For the anthropomorphic phantom study, the mean reader scores for images resulting from the d\u27gen‐AEC method were 3.3 (reference image), 3.5 (IR1), 3.6 (IR2), 3.5 (IR3), and 2.2 (IR4). When using the d\u27gen‐AEC method, the observers’ IQ scores for the reference reconstruction were statistical equivalent to the scores for IR1, IR2, and IR3 iterative reconstructions (P \u3e 0.35). The d\u27gen‐AEC method achieved this equivalent IQ at lower dose for the IR scans compared to the reference scans. Conclusions A novel AEC method, based on a generalized detectability index, was investigated. The proposed method can be used with some existing AEC systems to derive the tube current profile for iterative reconstruction algorithms. The results provide preliminary evidence that the proposed d\u27gen‐AEC can produce similar IQ across different iterative reconstruction approaches at different dose levels

Polarization Dependent Coupling of Whispering Gallery Modes in Microspheres

Two sets of resonances in glass microspheres attached to a standard communication-grade single-mode optical fiber have been observed. It has been found that the strength of the resonances depends strongly on the polarization of the coupled light. Furthermore, the position of the resonances in the wavelength domain depends on the polarization of light in the optical fiber with maximum magnitudes shifted by approximately 45

Chl a fluorescence and HCO₃-transport in the cyanobacterium Synechoccus UTEX 625

Indicates the usefulness of Chl a fluorescence as an indirect, non-invasive method for measuring DIC transport

Progression and adherence to an individually prescribed and supervised resistance training intervention in older adults recovering in hospital from lower limb fragility fracture

This study evaluated adherence and progression with a 12-week resistance training program amongst a sample of older adults recovering in hospital from lower limb fragility fracture. Forty-nine participants (mean age 84 years) commenced the resistance training program seven days after the injury. The exercise prescription involved training of the hip and knee extensors, hip abductors, and ankle plantar- and dorsi flexors using resistive bands. Exercise sessions were completed tri-weekly for six weeks under supervision by a physiotherapist and tri-weekly for an additional six weeks independently. Adherence was assessed as the proportion of exercise sessions completed of those prescribed and any progression in resistance was documented. Level of adherence was not found to be influenced by age, gender, cognition or strength but was greater amongst those admitted from the community setting and for the first six weeks when supervision was present. Participants were able to obtain similar levels of resistance for the injured side compared to the noninjured side for all exercises excluding hip abduction and those admitted from the community setting achieved higher levels of resistance compared to those admitted from the residential care setting. These findings suggest that an early resistance training program is feasible and well tolerated amongst older adults recovering from lower limb fragility fracture. Further work is necessary to determine how this level of resistance training translates into functional improvements and how to improve adherence levels in clinical rehabilitation settings

Are people in residential care entitled to receive rehabilitation services following hip fracture? Views of the public from a citizens' jury.

BACKGROUND:Access to rehabilitation services for people living in residential care facilities is frequently limited. A randomised trial of a hospital outreach hip fracture rehabilitation program in residential care facilities has demonstrated improvements in mobility at four weeks and quality of life at 12 months but was not considered cost-effective by standard health economic metrics. The current study aimed to explore the general public's views on issues involved in the allocation of rehabilitation resources for residents of care facilities. METHODS:A citizens' jury comprising 13 purposively sampled members of the general public, representative of the South Australian age, gender and household income profile. The jury considered the questions "Should there be an investment of physical rehabilitation services in residential care for older people following a hip fracture? If so, what is the best way of providing this service (considering funding, models of service delivery and equity)?" Deliberations were in the context of a state-wide health reform program. The jury was conducted over two days with an experienced independent facilitator, addressing questions developed by a steering group of research academics and clinicians. RESULTS:The mean age of the citizens' jury members was 43 (range 26 to 61). Eleven members voted for investment in outreach hospital rehabilitation services in residential aged care. All jurors agreed a number of strategies in addition to investment should be implemented, including health care planning and decision making, increased emphasis on hip fracture prevention, training of aged care staff in rehabilitation and routine provision of hospital discharge summaries to families. The jury further advocated for an increased focus on rehabilitation in residential care, potentially through accreditation criteria, increasing health literacy of residents and families, implementation of age friendly environment strategies and improving connections of care facilities with community, hospital and tertiary services. CONCLUSIONS:This citizens' jury representative of the general public recommends that regardless of dementia and frailty, people who live in residential care and are walking and fracture their hips should have access to hospital outreach rehabilitation and recovery services