80 research outputs found

    The 2D Euler-Poisson System with Spherical Symmetry

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    This article concerns the global-in-time existence of smooth solutions with small amplitude to two space dimensional Euler-Poisson system. The main difficulty lies in the slow time decay (1+t)−1(1+t)^{-1} of the linear system. Inspired by Ozawa, Tsutaya, and Tsutsumi's work, we show that such smooth solutions exist for radially symmetric flows

    Global Hilbert Expansion for the Vlasov-Poisson-Boltzmann System

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    We study the Hilbert expansion for small Knudsen number ε\varepsilon for the Vlasov-Boltzmann-Poisson system for an electron gas. The zeroth order term takes the form of local Maxwellian: $ F_{0}(t,x,v)=\frac{\rho_{0}(t,x)}{(2\pi \theta_{0}(t,x))^{3/2}} e^{-|v-u_{0}(t,x)|^{2}/2\theta_{0}(t,x)},\text{\ }\theta_{0}(t,x)=K\rho_{0}^{2/3}(t,x).OurmainresultstatesthatiftheHilbertexpansionisvalidat Our main result states that if the Hilbert expansion is valid at t=0forwell−preparedsmallinitialdatawithirrotationalvelocity for well-prepared small initial data with irrotational velocity u_0,thenitisvalidfor, then it is valid for 0\leq t\leq \varepsilon ^{-{1/2}\frac{2k-3}{2k-2}},where where \rho_{0}(t,x)and and u_{0}(t,x)satisfytheEuler−Poissonsystemformonatomicgas satisfy the Euler-Poisson system for monatomic gas \gamma=5/3$

    Two-Color Coherent Photodissociation of Nitrogen Oxide in Intense Laser Fields

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    A simple one-dimensional semi-classical model with a Morse potential is used to investigate the possibility of two-color infrared multi-photon dissociation of vibrationally excited nitrogen oxide. The amplitude ratio effects and adiabatic effects are investigated. Some initial states are found to have thresholds smaller than expected from single-mode considerations and multiple thresholds exist for initial states up to 32. PACS: 42.50.HzComment: 3 pages, old papers, add source files to replace original postscrip

    Emerging executive functioning and motor development in infants at high and low risk for autism spectrum disorder

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    Existing evidence suggests executive functioning (EF) deficits may be present in children with autism spectrum disorder (ASD) by 3 years of age. It is less clear when, prior to 3 years, EF deficits may emerge and how EF unfold over time. The contribution of motor skill difficulties to poorer EF in children with ASD has not been systematically studied. We investigated the developmental trajectory of EF in infants at high and low familial risk for ASD (HR and LR) and the potential associations between motor skills, diagnostic group, and EF performance. Participants included 186 HR and 76 LR infants. EF (A-not-B), motor skills (Fine and Gross Motor), and cognitive ability were directly assessed at 12 months and 24 months of age. Participants were directly evaluated for ASD at 24 months using DSM-IV-TR criteria and categorized as HR-ASD, HR-Negative, and LR-Negative. HR-ASD and HR-Negative siblings demonstrated less improvement in EF over time compared to the LR-Negative group. Motor skills were associated with group and EF performance at 12 months. No group differences were found at 12 months, but at 24 months, the HR-ASD and HR-Negative groups performed worse than the LR-Negative group overall after controlling for visual reception and maternal education. On reversal trials, the HR-ASD group performed worse than the LR-Negative group. Motor skills were associated with group and EF performance on reversal trials at 24 months. Findings suggest that HR siblings demonstrate altered EF development and that motor skills may play an important role in this process

    Reach and adoption of a Geriatric Emergency Department Accreditation program in the United States

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    STUDY OBJECTIVE: The objectives of this study were to describe the reach and adoption of Geriatric Emergency Department Accreditation (GEDA) program and care processes instituted at accredited geriatric emergency departments (EDs). METHODS: We analyzed a cross-section of a cohort of US EDs that received GEDA from May 2018 to March 2021. We obtained data from the American College of Emergency Physicians and publicly available sources. Data included GEDA level, geographic location, urban/rural designation, and care processes instituted. Frequencies and proportions and median and interquartile ranges were used to summarize categorical and continuous data, respectively. RESULTS: Over the study period, 225 US geriatric ED accreditations were issued and included in our analysis-14 Level 1, 21 Level 2, and 190 Level 3 geriatric EDs; 5 geriatric EDs reapplied and received higher-level accreditation after initial accreditation at a lower level. Only 9 geriatric EDs were in rural regions. There was significant heterogeneity in protocols enacted at geriatric EDs; minimizing urinary catheter use and fall prevention were the most common. CONCLUSION: There has been rapid growth in geriatric EDs, driven by Level 3 accreditation. Most geriatric EDs are in urban areas, indicating the potential need for expansion beyond these areas. Future research evaluating the impact of GEDA on health care utilization and patient-oriented outcomes is needed

    Vitamin D Is Required for ILC3 Derived IL-22 and Protection From Citrobacter rodentium Infection

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    Citrobacter rodentium is a gastrointestinal infection that requires early IL-22 from group 3 innate lymphoid cells (ILC3) for resistance. The role of vitamin D in the clearance of C. rodentium infection was tested in vitamin D sufficient (D+) and vitamin D deficient (D-) wildtype (WT) and Cyp27B1 (Cyp) KO mice (unable to produce the high affinity vitamin D ligand 1,25(OH)2D, 1,25D). Feeding Cyp KO mice D- diets reduced vitamin D levels and prevented synthesis of 1,25D. D- (WT and Cyp KO) mice had fewer ILC3 cells and less IL-22 than D+ mice. D- Cyp KO mice developed a severe infection that resulted in the lethality of the mice by d14 post-infection. T and B cell deficient D- Rag KO mice also developed a severe and lethal infection with C. rodentium compared to D+ Rag KO mice. D- WT mice survived the infection but took significantly longer to clear the C. rodentium infection than D+ WT or D+ Cyp KO mice. Treating infected D- Cyp KO mice with IL-22 protected the mice from lethality. Treating the D- WT mice with 1,25D reconstituted the ILC3 cells in the colon and protected the mice from C. rodentium. IL-22 treatment of D- WT mice eliminated the need for vitamin D to clear the C. rodentium infection. Vitamin D is required for early IL-22 production from ILC3 cells and protection from enteric infection with C. rodentium

    Association of Treatment Effects on Early Change in Urine Protein and Treatment Effects on GFR Slope in IgA Nephropathy:An Individual Participant Meta-analysis

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    Rationale & Objective: An early change in proteinuria is considered a reasonably likely surrogate end point in immunoglobulin A nephropathy (IgAN) and can be used as a basis for accelerated approval of therapies, with verification in a postmarketing confirmatory trial. Glomerular filtration rate (GFR) slope is a recently validated surrogate end point for chronic kidney disease progression and may be considered as the end point used for verification. We undertook a metaanalysis of clinical trials in IgAN to compare treatment effects on change in proteinuria versus change in estimated GFR (eGFR) slope. Study Design: Individual patient-level metaanalysis. Setting & Study Populations: Individual data of 1,037 patients from 12 randomized trials. Selection Criteria for Studies: Randomized trials of IgAN with proteinuria measurements at baseline and 6 (range, 2.5-14) months and at least a further 1 year of follow-up for the clinical outcome. Analytical Approach: For each trial, we estimated the treatment effects on proteinuria and on the eGFR slope, computed as the total slope starting at baseline or the chronic slope starting 3 months after randomization. We used a Bayesian mixed-effects analysis to relate the treatment effects on proteinuria to effects on GFR slope across these studies and developed a prediction model for the treatment effect on the GFR slope based on the effect on proteinuria. Results: Across all studies, treatment effects on proteinuria accurately predicted treatment effects on the total slope at 3 years (median R-2 = 0.88; 95% Bayesian credible interval [BCI], 0.06-1) and on the chronic slope (R-2 = 0.98; 95% BCI, 0.29-1). For future trials, an observed treatment effect of approximately 30% reduction in proteinuria would confer probabilities of at least 90% for nonzero treatment benefits on the total and chronic slopes of eGFR. We obtained similar results for proteinuria at 9 and 12 months and total slope at 2 years. Limitations: Study population restricted to 12 trials of small sample size, leading to wide BCIs. There was heterogeneity among trials with respect to study design and interventions. Conclusions: These results provide new evidence supporting that early reduction in proteinuria can be used as a surrogate end point for studies of chronic kidney disease progression in IgAN

    Early brain development in infants at high risk for autism spectrum disorder

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    Brain enlargement has been observed in children with Autism Spectrum Disorder (ASD), but the timing of this phenomenon and its relationship to the appearance of behavioral symptoms is unknown. Retrospective head circumference and longitudinal brain volume studies of 2 year olds followed up at age 4 years, have provided evidence that increased brain volume may emerge early in development.1, 2 Studies of infants at high familial risk for autism can provide insight into the early development of autism and have found that characteristic social deficits in ASD emerge during the latter part of the first and in the second year of life3,4. These observations suggest that prospective brain imaging studies of infants at high familial risk for ASD might identify early post-natal changes in brain volume occurring before the emergence of an ASD diagnosis. In this prospective neuroimaging study of 106 infants at high familial risk of ASD and 42 low-risk infants, we show that cortical surface area hyper-expansion between 6-12 months of age precedes brain volume overgrowth observed between 12-24 months in the 15 high-risk infants diagnosed with autism at 24 months. Brain volume overgrowth was linked to the emergence and severity of autistic social deficits. A deep learning algorithm primarily using surface area information from brain MRI at 6 and 12 months of age predicted the diagnosis of autism in individual high-risk children at 24 months (with a positive predictive value of 81%, sensitivity of 88%). These findings demonstrate that early brain changes unfold during the period in which autistic behaviors are first emerging

    Friend matters: sex differences in social language during autism diagnostic interviews

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    Background: Autistic individuals frequently experience social communication challenges. Girls are diagnosed with autism less often than boys even when their symptoms are equally severe, which may be due to insufficient understanding of the way autism manifests in girls. Differences in the behavioral presentation of autism, including how people talk about social topics, could contribute to these persistent problems with identification. Despite a growing body of research suggesting that autistic girls and boys present distinct symptom profiles in a variety of domains, including social attention, friendships, social motivation, and language, differences in the way that autistic boys and girls communicate verbally are not yet well understood. Closely analyzing boys’ and girls’ socially-focused language during semi-structured clinical assessments could shed light on potential sex differences in the behavioral presentation of autistic individuals that may prove useful for identifying and effectively supporting autistic girls. Here, we compare social word use in verbally fluent autistic girls and boys during the interview sections of the ADOS-2 Module 3 and measure associations with clinical phenotype. Methods: School-aged girls and boys with autism (N = 101, 25 females; aged 6–15) were matched on age, IQ, and parent/clinician ratings of autism symptom severity. Our primary analysis compared the number of social words produced by autistic boys and girls (normalized to account for differences in total word production). Social words are words that make reference to other people, including friends and family. Results: There was a significant main effect of sex on social word production, such that autistic girls used more social words than autistic boys. To identify the specific types of words driving this effect, additional subcategories of friend and family words were analyzed. There was a significant effect of sex on friend words, with girls using significantly more friend words than boys. However, there was no significant main effect of sex on family words, suggesting that sex differences in social word production may be driven by girls talking more about friends compared to boys, not family. To assess relationships between word use and clinical phenotype, we modeled ADOS-2 Social Affect (SA) scores as a function of social word production. In the overall sample, social word use correlated significantly with ADOS-2 SA scores, indicating that participants who used more social words were rated as less socially impaired by clinicians. However, when examined in each sex separately, this result only held for boys. Limitations: This study cannot speak to the ways in which social word use may differ for younger children, adults, or individuals who are not verbally fluent; in addition, there were more autistic boys than girls in our sample, making it difficult to detect small effects. Conclusions: Autistic girls used significantly more social words than boys during a diagnostic assessment—despite being matched on age, IQ, and both parent- and clinician-rated autism symptom severity. Sex differences in linguistic markers of social phenotype in autism are especially important in light of the late or missed diagnoses that disproportionately affect autistic girls. Specifically, heightened talk about social topics could complicate autism referral and diagnosis when non-clinician observers expect a male-typical pattern of reduced social focus, which autistic girls may not always exhibit
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