Thermal Energy Transport in Oxide Nuclear Fuel.

To efficiently capture the energy of the nuclear bond, advanced nuclear reactor concepts seek solid fuels that must withstand unprecedented temperature and radiation extremes. In these advanced fuels, thermal energy transport under irradiation is directly related to reactor performance as well as reactor safety. The science of thermal transport in nuclear fuel is a grand challenge as a result of both computational and experimental complexities. Here we provide a comprehensive review of thermal transport research on two actinide oxides: one currently in use in commercial nuclear reactors, uranium dioxide (UO2), and one advanced fuel candidate material, thorium dioxide (ThO2). In both materials, heat is carried by lattice waves or phonons. Crystalline defects caused by fission events effectively scatter phonons and lead to a degradation in fuel performance over time. Bolstered by new computational and experimental tools, researchers are now developing the foundational work necessary to accurately model and ultimately control thermal transport in advanced nuclear fuels. We begin by reviewing research aimed at understanding thermal transport in perfect single crystals. The absence of defects enables studies that focus on the fundamental aspects of phonon transport. Next, we review research that targets defect generation and evolution. Here the focus is on ion irradiation studies used as surrogates for damage caused by fission products. We end this review with a discussion of modeling and experimental efforts directed at predicting and validating mesoscale thermal transport in the presence of irradiation defects. While efforts in these research areas have been robust, challenging work remains in developing holistic tools to capture and predict thermal energy transport across widely varying environmental conditions.

Antibiotics prior to age 2 years have limited association with preschool growth trajectory.

BACKGROUND: Prior studies of early antibiotic use and growth have shown mixed results, primarily on cross-sectional outcomes. This study examined the effect of oral antibiotics before age 24 months on growth trajectory at age 2-5 years. METHODS: We captured oral antibiotic prescriptions and anthropometrics from electronic health records through PCORnet, for children with ≥1 height and weight at 0-12 months of age, ≥1 at 12-30 months, and ≥2 between 25 and 72 months. Prescriptions were grouped into episodes by time and by antimicrobial spectrum. Longitudinal rate regression was used to assess differences in growth rate from 25 to 72 months of age. Models were adjusted for sex, race/ethnicity, steroid use, diagnosed asthma, complex chronic conditions, and infections. RESULTS: 430,376 children from 29 health U.S. systems were included, with 58% receiving antibiotics before 24 months. Exposure to any antibiotic was associated with an average 0.7% (95% CI 0.5, 0.9, p < 0.0001) greater rate of weight gain, corresponding to 0.05 kg additional weight. The estimated effect was slightly greater for narrow-spectrum (0.8% [0.6, 1.1]) than broad-spectrum (0.6% [0.3, 0.8], p < 0.0001) drugs. There was a small dose response relationship between the number of antibiotic episodes and weight gain. CONCLUSION: Oral antibiotic use prior to 24 months of age was associated with very small changes in average growth rate at ages 2-5 years. The small effect size is unlikely to affect individual prescribing decisions, though it may reflect a biologic effect that can combine with others.

ß1 integrin is a sensor of blood flow direction.

Endothelial cell (EC) sensing of fluid shear stress direction is a critical determinant of vascular health and disease. Unidirectional flow induces EC alignment and vascular homeostasis, whereas bidirectional flow has pathophysiological effects. ECs express several mechanoreceptors that respond to flow, but the mechanism for sensing shear stress direction is poorly understood. We determined, by using in vitro flow systems and magnetic tweezers, that ß1 integrin is a key sensor of force direction because it is activated by unidirectional, but not bidirectional, shearing forces. ß1 integrin activation by unidirectional force was amplified in ECs that were pre-sheared in the same direction, indicating that alignment and ß1 integrin activity has a feedforward interaction, which is a hallmark of system stability. En face staining and EC-specific genetic deletion studies in the murine aorta revealed that ß1 integrin is activated and is essential for EC alignment at sites of unidirectional flow but is not activated at sites of bidirectional flow. In summary, ß1 integrin sensing of unidirectional force is a key mechanism for decoding blood flow mechanics to promote vascular homeostasis.This article has an associated First Person interview with the first author of the paper.

A Predictive Model for Identification of Children at Risk of Subsequent High-Frequency Utilization of the Emergency Department for Asthma.

BACKGROUND: Asthma is the most common chronic condition among children with high-frequency emergency department (ED) utilization. Previous research has shown in outpatients seen for asthma that acute care visits predict subsequent health care utilization. Among ED patients, however, the optimal method of predicting subsequent ED utilization remains to be described. The goal of this study was to create a predictive model to identify children in the ED who are at risk of subsequent high-frequency utilization of the ED for asthma. METHODS: We used 3 years of data, 2013-2015, drawn from the electronic health records at a tertiary care, urban, children's hospital that is a high-volume center for asthma care. Data were split into a derivation (50%) and validation/test (50%) set, and 3 models were created for testing: (1) all index patients; (2) removing patients with complex chronic conditions; and (3) subset of patients with in-network care on whom more clinical data were available. Each multivariable model was then tested in the validation set, and its performance evaluated by predicting error rate, calculation of a receiver operating characteristic (ROC) curve, and identification of the optimal cutpoint to maximize sensitivity and specificity. RESULTS: There were 5535 patients with index ED visits, of whom 2767 were in the derivation set and 2768 in the validation set. Of the 5535 patients, 125 patients (2.3%) had 4 or more visits for asthma in the outcome year. Significant predictors in models 1 and 2 were age and number of prior ED visits for asthma. For model 3 (additional clinical information available), the predictors were number of prior ED visits for asthma, number of primary care visits, and not having a controller medication. Areas under the ROC curve were 0.77 for model 1, 0.80 for model 2, and 0.77 for model 3. CONCLUSIONS: Administrative data available at the time of ED triage can predict subsequent high utilization of the ED, with areas under the ROC curve of 0.77 to 0.80. The addition of clinical variables did not improve the model performance. These models provide useful tools for researchers interested in examining intervention efficacy by predicted risk group.

The use of echinocandins in hospitalized children in the United States.

Echinocandins are used for treatment of invasive candidiasis, but data on their use in children are limited. We sought to describe the epidemiology of echinocandin use in hospitalized children in the United States. We performed a retrospective cohort study of children <18 years of age hospitalized between January 2005 and December 2015 and exposed to ≥1 day of a systemic antifungal agent using the Pediatric Health Information System (PHIS) database. Univariate analyses compared recipients of two echinocandin agents, caspofungin and micafungin. Crude prescribing rates of each antifungal group were calculated across hospitals and per year. The rate of antifungal agent prescribing over time was assessed using two-level mixed-effects negative binomial regression, accounting for variability in prescribing by hospital over time. From 2005 to 2015, fluconazole was prescribed most often (n = 148,859, 74.3%), followed by mould-active triazoles (n = 36,131, 18.0%), amphotericin products (n = 29,008, 14.5%), and echinocandins (n = 28,371, 14.2%). The crude rate of systemic antifungal prescribing decreased across all PHIS hospitals from 36.3 to 33.8 per 1000 admissions during the study period, but echinocandin prescribing increased from 2.2 to 7.2 per 1000 admissions. A mixed effects regression model revealed that echinocandin prescribing increased by 15.1% per year (95% CI 11.2-19.2). Echinocandin administration increased from 6.1% to 21.0% of admissions during which a systemic antifungal agent was given. In conclusion, echinocandin use has increased significantly over time, accounting for an increasing proportion of systemic antifungal prescribing in children.

Variation in Positive End-Expiratory Pressure Levels for Mechanically Ventilated Extremely Low Birth Weight Infants.

OBJECTIVE: To test the hypothesis that significant positive end-expiratory pressure (PEEP) level variation exists between neonatal centers. STUDY DESIGN: We performed a secondary analysis cohort study of the Nasal Intermittent Positive-Pressure Ventilation trial. Our study population was extremely low birth weight infants requiring mechanical ventilation within 28 days of life. The exposure was neonatal center; 34 international centers participated in the trial. Subjects from centers with fewer than 5 eligible cases were excluded. The main outcome was the maximal PEEP level used during the first course of mechanical ventilation. Infant characteristics judged a priori to directly influence clinical PEEP level selection and all characteristics associated with PEEP at P <.05 in bivariable analyses were included with and without center in multivariable linear regression models. Variation in PEEP level use between centers following adjustment for infant characteristics was assessed. RESULTS: A total of 278 extremely low birth weight infants from 17 centers were included. Maximal PEEP ranged from 3 to 9 cm H2O, mean = 5.7 (SD = 0.9). Significant variation between centers remained despite adjustment for infant characteristics (P < .0001). Further, center alone explained a greater proportion of the PEEP level variation than all infant characteristics combined. CONCLUSIONS: Marked variation in PEEP levels for extremely low birth weight infants exists between neonatal centers. Research providing evidence-based guidance for this important aspect of respiratory care in preterm infants at high risk of lung injury is needed. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00433212.

Intravenous Versus Oral Antibiotics for the Prevention of Treatment Failure in Children With Complicated Appendicitis: Has the Abandonment of Peripherally Inserted Catheters Been Justified?

OBJECTIVE: To compare treatment failure leading to hospital readmission in children with complicated appendicitis who received oral versus intravenous antibiotics after discharge. BACKGROUND: Antibiotics are often employed after discharge to prevent treatment failure in children with complicated appendicitis, although existing studies comparing intravenous and oral antibiotics for this purpose are limited. METHODS: We identified all patients aged 3 to 18 years undergoing appendectomy for complicated appendicitis, who received postdischarge antibiotics at 35 childrens hospitals from 2009 to 2012. Discharge codes were used to identify study subjects from the Pediatric Health Information System database, and chart review confirmed eligibility, treatment assignment, and outcomes. Exposure status was based on outpatient antibiotic therapy, and analysis used optimal and full matching methods to adjust for demographic and clinical characteristics. Treatment failure (defined as an organ-space infection) requiring inpatient readmission was the primary outcome. Secondary outcomes included revisits from any cause to either the inpatient or emergency department setting. RESULTS: In all, 4579 patients were included (median: 99/hospital), and utilization of intravenous antibiotics after discharge ranged from 0% to 91.7% across hospitals. In the matched analysis, the rate of treatment failure was significantly higher for the intravenous group than the oral group [odds ratio (OR) 1.74, 95% confidence interval (CI) 1.05-2.88; risk difference: 4.0%, 95% CI 0.4-7.6%], as was the rate of all-cause revisits (OR 2.11, 95% CI 1.44-3.11; risk difference: 9.4%, 95% CI 4.7-14.2%). The rate of peripherally inserted central catheter line complications was 3.2% in the intravenous group, and drug reactions were rare in both groups (intravenous: 0.7%, oral: 0.5%). CONCLUSIONS: Compared with oral antibiotics, use of intravenous antibiotics after discharge in children with complicated appendicitis was associated with higher rates of both treatment failure and all-cause hospital revisits.

Association of Broad- vs Narrow-Spectrum Antibiotics With Treatment Failure, Adverse Events, and Quality of Life in Children With Acute Respiratory Tract Infections.

Importance: Acute respiratory tract infections account for the majority of antibiotic exposure in children, and broad-spectrum antibiotic prescribing for acute respiratory tract infections is increasing. It is not clear whether broad-spectrum treatment is associated with improved outcomes compared with narrow-spectrum treatment. Objective: To compare the effectiveness of broad-spectrum and narrow-spectrum antibiotic treatment for acute respiratory tract infections in children. Design, Setting, and Participants: A retrospective cohort study assessing clinical outcomes and a prospective cohort study assessing patient-centered outcomes of children between the ages of 6 months and 12 years diagnosed with an acute respiratory tract infection and prescribed an oral antibiotic between January 2015 and April 2016 in a network of 31 pediatric primary care practices in Pennsylvania and New Jersey. Stratified and propensity score-matched analyses to account for confounding by clinician and by patient-level characteristics, respectively, were implemented for both cohorts. Exposures: Broad-spectrum antibiotics vs narrow-spectrum antibiotics. Main Outcomes and Measures: In the retrospective cohort, the primary outcomes were treatment failure and adverse events 14 days after diagnosis. In the prospective cohort, the primary outcomes were quality of life, other patient-centered outcomes, and patient-reported adverse events. Results: Of 30 159 children in the retrospective cohort (19 179 with acute otitis media; 6746, group A streptococcal pharyngitis; and 4234, acute sinusitis), 4307 (14%) were prescribed broad-spectrum antibiotics including amoxicillin-clavulanate, cephalosporins, and macrolides. Broad-spectrum treatment was not associated with a lower rate of treatment failure (3.4% for broad-spectrum antibiotics vs 3.1% for narrow-spectrum antibiotics; risk difference for full matched analysis, 0.3% [95% CI, -0.4% to 0.9%]). Of 2472 children enrolled in the prospective cohort (1100 with acute otitis media; 705, group A streptococcal pharyngitis; and 667, acute sinusitis), 868 (35%) were prescribed broad-spectrum antibiotics. Broad-spectrum antibiotics were associated with a slightly worse child quality of life (score of 90.2 for broad-spectrum antibiotics vs 91.5 for narrow-spectrum antibiotics; score difference for full matched analysis, -1.4% [95% CI, -2.4% to -0.4%]) but not with other patient-centered outcomes. Broad-spectrum treatment was associated with a higher risk of adverse events documented by the clinician (3.7% for broad-spectrum antibiotics vs 2.7% for narrow-spectrum antibiotics; risk difference for full matched analysis, 1.1% [95% CI, 0.4% to 1.8%]) and reported by the patient (35.6% for broad-spectrum antibiotics vs 25.1% for narrow-spectrum antibiotics; risk difference for full matched analysis, 12.2% [95% CI, 7.3% to 17.2%]). Conclusions and Relevance: Among children with acute respiratory tract infections, broad-spectrum antibiotics were not associated with better clinical or patient-centered outcomes compared with narrow-spectrum antibiotics, and were associated with higher rates of adverse events. These data support the use of narrow-spectrum antibiotics for most children with acute respiratory tract infections.

Multivariate analysis of longitudinal rates of change.

Longitudinal data allow direct comparison of the change in patient outcomes associated with treatment or exposure. Frequently, several longitudinal measures are collected that either reflect a common underlying health status, or characterize processes that are influenced in a similar way by covariates such as exposure or demographic characteristics. Statistical methods that can combine multivariate response variables into common measures of covariate effects have been proposed in the literature. Current methods for characterizing the relationship between covariates and the rate of change in multivariate outcomes are limited to select models. For example, 'accelerated time' methods have been developed which assume that covariates rescale time in longitudinal models for disease progression. In this manuscript, we detail an alternative multivariate model formulation that directly structures longitudinal rates of change and that permits a common covariate effect across multiple outcomes. We detail maximum likelihood estimation for a multivariate longitudinal mixed model. We show via asymptotic calculations the potential gain in power that may be achieved with a common analysis of multiple outcomes. We apply the proposed methods to the analysis of a trivariate outcome for infant growth and compare rates of change for HIV infected and uninfected infants. Copyright © 2016 John Wiley & Sons, Ltd.

Comparative effectiveness of fungicidal vs. fungistatic therapies for the treatment of paediatric candidaemia.

Adult data suggest that echinocandins for treatment of candidaemia are associated with decreased mortality, attributed to their fungicidal activity. There are limited data comparing antifungals in children. We compared 30-day all-cause mortality among paediatric candidaemia patients treated with fungicidal vs. fungistatic agents. All inpatients (>6 months and <19 years of age) with candidaemia between 2000 and 2012 at The Children's Hospital of Philadelphia were retrospectively identified. Definitive therapy with fungicidal (amphotericin B and caspofungin) agents was compared with fungistatic (fluconazole) agents. A propensity score model generated the inverse probability of receiving a fungicidal agent, which was included in a weighted logistic regression model. Among 203 children meeting inclusion criteria, 151 (74.4%) and 52 (25.6%) received a fungicidal and fungistatic agent, respectively. Overall, 18 (8.9%) patients died within 30 days. There was no statistically significant difference in mortality between patients started on a fungicidal or fungistatic agent (OR: 2.19, 95% CI: 0.42-11.48). In a propensity score-weighted model, definitive therapy with a fungicidal agent did not result in a significant decrease in mortality. These data suggest that both agents can be considered definitive therapy for paediatric candidaemia. The results should be interpreted with caution given the small sample size. Larger cohort studies are needed.

Antibiotic Exposure During the First 6 Months of Life and Weight Gain During Childhood.

IMPORTANCE: Early-life antibiotic exposure has been associated with increased adiposity in animal models, mediated through the gut microbiome. Infant antibiotic exposure is common and often inappropriate. Studies of the association between infant antibiotics and childhood weight gain have reported inconsistent results. OBJECTIVE: To assess the association between early-life antibiotic exposure and childhood weight gain. DESIGN AND SETTING: Retrospective, longitudinal study of singleton births and matched longitudinal study of twin pairs conducted in a network of 30 pediatric primary care practices serving more than 200,000 children of diverse racial and socioeconomic backgrounds across Pennsylvania, New Jersey, and Delaware. PARTICIPANTS: Children born between November 1, 2001, and December 31, 2011, at 35 weeks' gestational age or older, with birth weight of 2000 g or more and in the fifth percentile or higher for gestational age, and who had a preventive health visit within 14 days of life and at least 2 additional visits in the first year of life. Children with complex chronic conditions and those who received long-term antibiotics or multiple systemic corticosteroid prescriptions were excluded. We included 38,522 singleton children and 92 twins (46 matched pairs) discordant in antibiotic exposure. Final date of follow-up was December 31, 2012. EXPOSURE: Systemic antibiotic use in the first 6 months of life. MAIN OUTCOMES AND MEASURES: Weight, measured at preventive health visits from age 6 months through 7 years. RESULTS: Of 38,522 singleton children (50% female; mean birth weight, 3.4 kg), 5287 (14%) were exposed to antibiotics during the first 6 months of life (at a mean age of 4.3 months). Antibiotic exposure was not significantly associated with rate of weight change (0.7%; 95% CI, -0.1% to 1.5%; P = .07, equivalent to approximately 0.05 kg; 95% CI, -0.004 to 0.11 kg of added weight gain between age 2 years and 5 years). Among 92 twins (38% female; mean birth weight, 2.8 kg), the 46 twins who were exposed to antibiotics during the first 6 months of life received them at a mean age of 4.5 months. Antibiotic exposure was not significantly associated with a weight difference (-0.09 kg; 95% CI, -0.26 to 0.08 kg; P = .30). CONCLUSIONS AND RELEVANCE: Exposure to antibiotics within the first 6 months of life compared with no exposure was not associated with a statistically significant difference in weight gain through age 7 years. There are many reasons to limit antibiotic exposure in young, healthy children, but weight gain is likely not one of them.

Mechanoresponsive networks controlling vascular inflammation.

Atherosclerosis is a chronic inflammatory disease of arteries that develops preferentially at branches and bends that are exposed to disturbed blood flow. Vascular function is modified by flow, in part, via the generation of mechanical forces that alter multiple physiological processes in endothelial cells. Shear stress has profound effects on vascular inflammation; high uniform shear stress prevents leukocyte recruitment to the vascular wall by reducing endothelial expression of adhesion molecules and other inflammatory proteins, whereas low oscillatory shear stress has the opposite effects. Here, we review the molecular mechanisms that underpin the effects of shear stress on endothelial inflammatory responses. They include shear stress regulation of inflammatory mitogen-activated protein kinase and nuclear factor-κB signaling. High shear suppresses these pathways through the induction of several negative regulators of inflammation, whereas low shear promotes inflammatory signaling. Furthermore, we summarize recent studies indicating that inflammatory signaling is highly sensitive to pulse wave frequencies, magnitude, and direction of flow. Finally, the importance of systems biology approaches (including omics studies and functional screening) to identify novel mechanosensitive pathways is discussed.

Direct regression models for longitudinal rates of change.

Comparing rates of growth, or rates of change, across covariate-defined subgroups is a primary objective for many longitudinal studies. In the special case of a linear trend over time, the interaction between a covariate and time will characterize differences in longitudinal rates of change. However, in the presence of a non-linear longitudinal trajectory, the standard mean regression approach does not permit parsimonious description or inference regarding differences in rates of change. Therefore, we propose regression methodology for longitudinal data that allows a direct, structured comparison of rates across subgroups even in the presence of a non-linear trend over time. Our basic longitudinal rate regression method assumes a proportional difference across covariate groups in the rate of change across time, but this assumption can be relaxed. Rates are compared relative to a generally specified time trend for which we discuss both parametric and non-parametric estimating approaches. We develop mixed model longitudinal methodology that explicitly characterizes subject-to-subject variation in rates, as well as a marginal estimating equation-based method. In addition, we detail a score test to detect violations of the proportionality assumption, and we allow time-varying rate effects as a natural generalization. Simulation results demonstrate potential gains in power for the longitudinal rate regression model relative to a linear mixed effects model in the presence of a non-linear trend in time. We apply our method to a study of growth among infants born to HIV infected mothers and conclude with a discussion of possible extensions for our methods.

Measuring electrical properties in semiconductor devices by pixelated STEM and off-axis electron holography (or convergent beams vs. plane waves).

We demonstrate the use of both pixelated differential phase contrast (DPC) scanning transmission electron microscopy (STEM) and off-axis electron holography (EH) for the measurement of electric fields and assess the advantages and limitations of each technique when applied to technologically relevant samples. Three different types of samples are examined, firstly a simple highly-doped Si pn junction. Then a SiGe superlattice is examined to evaluate the effects of the mean inner potential on the measured signal. Finally, an InGaN/GaN microwire light-emitting diode (LED) device is examined which has a polarization field, variations of mean inner potential and a wurtzite crystal lattice. We discuss aspects such as spatial resolution and sensitivity, and the concept of pseudo-field is defined. However, the most important point is the need to limit the influence of diffraction contrast to obtain accurate measurements. In this respect, the use of a plane electron wave for EH is clearly beneficial when compared to the use of a convergent beam for pixelated DPC STEM.

Assessing the Challenges of Nanotechnology-Driven Targeted Therapies: Development of Magnetically Directed Vectors for Targeted Cancer Therapies and Beyond.

Targeted delivery, in which therapeutic agents are preferentially concentrated at the diseased site, has the potential to improve therapeutic outcomes by minimizing off-target interactions in healthy tissue. Both passive and active methods of targeting delivery have been proposed, often with particular emphasis on cancer treatment. Passive methods rely on the overexpression of a biomarker in diseased tissue that can then be used to target the therapy. Active techniques involve physically guiding therapeutic agents toward the target region. Since the motion of magnetic particles can be remotely controlled by external magnetic fields, magnetic technologies have the potential to drive and hold drugs or other cargo at the required therapeutic site, increasing the localized dose while minimizing overall exposure. Directed motion may be generated either by simple magnetic attraction or by causing the particles to perform swimming strokes to produce propulsion. This chapter will compare the different strategies using magnetic nanotechnology to produce directed motion compatible with that required for targeted cargo delivery and magnetically assisted therapies and assess their potential to meet the challenges of operating within the human body.

Inversion of the Internal Electric Field due to Inhomogeneous Incorporation of Ge Dopants in GaN/AlN Heterostructures Studied by Off-Axis Electron Holography.

The engineering of the internal electric field inside III-nitride devices opens up interesting perspectives in terms of device design to boost the radiative efficiency, which is a pressing need in the ultraviolet and green-to-red spectral windows. In this context, it is of paramount importance to have access to a tool like off-axis electron holography which can accurately characterize the electrostatic potentials in semiconductor heterostructures with nanometer-scale resolution. Here, we investigate the distribution of the electrostatic potential and chemical composition in two 10-period AlN/GaN (20 nm/20 nm) multilayer samples, one of these being non-intentionally doped and the other with its GaN layers heavily doped with Ge at a nominal concentration ([Ge] = 2.0 ± 0.2 × 1021 cm-3) which is close to the solubility limit. The electron holography experiments demonstrate the effects of free carrier screening in the case of Ge doping. Furthermore, in the doped sample, an inversion of the internal electric field is observed in some of the AlN layers. A correlated study involving holography, electron dispersive X-ray spectroscopy, and theoretical calculations of the band diagram demonstrates that the perturbation of the potential can be attributed to Ge accumulation at the heterointerfaces, which paves the way to the use of Ge delta doping as a design tool to tune the electric fields in polar heterostructures.

Neural co-processors for restoring brain function: results from a cortical model of grasping.

Objective.A major challenge in designing closed-loop brain-computer interfaces is finding optimal stimulation patterns as a function of ongoing neural activity for different subjects and different objectives. Traditional approaches, such as those currently used for deep brain stimulation, have largely followed a manual trial-and-error strategy to search for effective open-loop stimulation parameters, a strategy that is inefficient and does not generalize to closed-loop activity-dependent stimulation.Approach.To achieve goal-directed closed-loop neurostimulation, we propose the use of brain co-processors, devices which exploit artificial intelligence to shape neural activity and bridge injured neural circuits for targeted repair and restoration of function. Here we investigate a specific type of co-processor called a 'neural co-processor' which uses artificial neural networks and deep learning to learn optimal closed-loop stimulation policies. The co-processor adapts the stimulation policy as the biological circuit itself adapts to the stimulation, achieving a form of brain-device co-adaptation. Here we use simulations to lay the groundwork for futurein vivotests of neural co-processors. We leverage a previously published cortical model of grasping, to which we applied various forms of simulated lesions. We used our simulations to develop the critical learning algorithms and study adaptations to non-stationarity in preparation for futurein vivotests.Main results.Our simulations show the ability of a neural co-processor to learn a stimulation policy using a supervised learning approach, and to adapt that policy as the underlying brain and sensors change. Our co-processor successfully co-adapted with the simulated brain to accomplish the reach-and-grasp task after a variety of lesions were applied, achieving recovery towards healthy function in the range 75%-90%.Significance.Our results provide the first proof-of-concept demonstration, using computer simulations, of a neural co-processor for adaptive activity-dependent closed-loop neurostimulation for optimizing a rehabilitation goal after injury. While a significant gap remains between simulations andin vivoapplications, our results provide insights on how such co-processors may eventually be developed for learning complex adaptive stimulation policies for a variety of neural rehabilitation and neuroprosthetic applications.

Implications of phonon anisotropy on thermal conductivity of fluorite oxides.

Fluorite oxides are attractive ionic compounds for a range of applications with critical thermal management requirements. In view of recent reports alluding to anisotropic thermal conductivity in this face-centered cubic crystalline systems, we perform a detailed analysis of the impact of direction-dependent phonon group velocities and lifetimes on the thermal transport of fluorite oxides. We demonstrate that the bulk thermal conductivity of this class of materials remains isotropic despite notable anisotropy in phonon lifetime and group velocity. However, breaking the symmetry of the phonon lifetime under external stimuli including boundary scattering present in nonequilibrium molecular dynamics simulations of finite size simulation cell gives rise to apparent thermal conductivity anisotropy. We observe that for accurate determination of thermal conductivity, it is important to consider phonon properties not only along high symmetry directions commonly measured in inelastic neutron or x-ray scattering experiments but also of those along lower symmetry. Our results suggests that certain low symmetry directions have a larger contribution to thermal conductivity compared to high symmetry ones.

Arthroscopic Subdeltoid Transfer of the Long Head of the Biceps Tendon to the Conjoint Tendon.

Surgical intervention is often recommended for refractory pathology affecting the biceps-labrum complex. Tenodesis of the long head of the biceps tendon (LHBT) is a widely accepted treatment modality; however, the optimal technique remains elusive. Arthroscopic subdeltoid transfer of the LHBT to the conjoint tendon, as described in this technical note, continues to demonstrate excellent clinical results. Its advantages include soft tissue-to-soft tissue healing, an advantageous biomechanical construct, and comprehensive evaluation and decompression of the LHBT including the extra-articular bicipital tunnel. The primary limitation of this procedure is the perceived learning curve for safe navigation within the subdeltoid space.

Local health departments and specific maternal and child health expenditures: relationships between spending and need.

OBJECTIVE: As a part of the Public Health Activities and Service Tracking study and in collaboration with partners in 2 Public Health Practice-Based Research Network states, we examined relationships between local health department (LHD) maternal and child health (MCH) expenditures and local needs. DESIGN: We used a multivariate pooled time-series design to estimate ecologic associations between expenditures in 3 MCH-specific service areas and related measures of need from 2005 to 2010 while controlling for other factors. MEASURES: Retrospective expenditure data from LHDs and for 3 MCH services represented annual investments in (1) Special Supplemental Nutrition for Women, Infants, and Children (WIC), (2) family planning, and (3) a composite of Maternal, Infant, Child, and Adolescent (MICA) service. Expenditure data from all LHDs in Florida and Washington were then combined with "need" and control variables. STUDY POPULATION: Our sample consisted of the 102 LHDs in Florida and Washington and the county (or multicounty) jurisdictions they serve. RESULTS: Expenditures for WIC and for our composite of MICA services were strongly associated with need among LHDs in the sample states. For WIC, this association was positive, and for MICA services, this association was negative. Family planning expenditures were weakly associated, in a positive direction. CONCLUSIONS: Findings demonstrate wide variations across programs and LHDs in relation to need and may underscore differences in how programs are funded. Programs with financial disbursements based on guidelines that factor in local needs may be better able to provide service as local needs grow than programs with less needs-based funding allocations.