On 2D Viscoelasticity with Small Strain

An exact two-dimensional rotation-strain model describing the motion of Hookean incompressible viscoelastic materials is constructed by the polar decomposition of the deformation tensor. The global existence of classical solutions is proved under the smallness assumptions only on the size of initial strain tensor. The proof of global existence utilizes the weak dissipative mechanism of motion, which is revealed by passing the partial dissipation to the whole system.Comment: Different contributions of strain and rotation of the deformation are studied for viscoelastic fluids of Oldroyd-B type in 2

A Likelihood-Based Approach to Detecting Aberrant Individuals in Confirmatory Factor Analytic Models

The study presented here was intended to develop and provide a relatively simple method for detecting aberrant observations in confirmatory factor analysis (CFA). This method exploited a by-product of Full Information Maximum Likelihood (FIML) estimation of these models, the log-likelihood produced for each individual observation. This score, after adjusting for missing data, indexed the degree to which a model fits for a specific individual. A simulation study was run to test this index, labelled adj_lli. Data were simulated under varying levels of covariance structure, proportion of aberrant data, and proportion of missing data. Each cell had 200 samples with n = 200. Additionally, adj_lli was compared to three existing methods: Reise and Widaman's (1999) INDCHI, Yung's (1997) method for detecting outliers in mixture models, and Bollen's A, a general multivariate method (1987). Results indicated that adj_lli was effective in detecting outliers and offered some advantages over three other methods.Doctor of Philosoph

Narrative skill in boys with fragile X syndrome with and without autism spectrum disorder

We examined recalled narratives of boys with fragile X syndrome with autism spectrum disorder (FXS-ASD; N=28) and without ASD (FXS-O; N=29), and compared them to those of boys with Down syndrome (DS; N=33) and typically developing boys (TD; N=39). Narratives were scored for mentions of macrostructural Story Grammar elements (Introduction, Relationship, Initiating Events, Internal Response, Attempts/Actions, and Ending). We found that narrative recall is predicted by short-term memory and nonverbal mental age levels in almost all groups (except TD), but not by expressive syntax or caregiver education. After adjusting for these covariates, there were no differences between the three groups with intellectual disability (ID). The FXS-ASD group, however, had significantly poorer performance than the TD group on the overall Story Grammar score, and both the FXS-O and FXS-ASD groups had lower Attempts/Actions scores than the TD group. We conclude that some form of narrative impairment may be associated with FXS, that this impairment may be shared by other forms of ID, and that the presence of ASD has a significantly detrimental effect on narrative recall

The Value of Occupational Therapy Student Participation in University-Based Student-Run Free Clinics in the United States

While student-run free clinic (SRFC) participation is well-documented among many health professions, no study has comprehensively characterized occupational therapy student participation. The purpose of this qualitative study was to understand both the current presence as well as educational impact of occupational therapy student participation in university-based SRFCs in the United States (U.S). Data collection occurred through a national survey and semi-structured interviews. Surveys were sent to representatives (e.g. program directors, faculty advisors, and student leaders) at all 190 accredited occupational therapy schools. Of these, 118 responded, for an overall response rate of 62.1%. Semi-structured interviews were conducted with a purposeful sample of physician’s assistant, medical, pharmacy, and occupational therapy students (N=9). Results showed that 12.7% of schools contributed volunteers to at least one SRFC (N=15). Themes included that occupational therapy students provided a unique perspective to the interprofessional team, educated other students about occupational therapy’s scope, and demonstrated strong patient interviewing skills. They also learned from opportunities to explore future career possibilities, engage in interdisciplinary teamwork, and practice skills in a safe space. Occupational therapy programs have a relatively low rate of participation (12.7%) in SRFCs compared to other health professions nationally. However, occupational therapy and other health professional students report that occupational therapy student participation creates important educational opportunities. These opportunities may strengthen occupational therapy’s role in interprofessional team-based care, especially within the emerging practice area of primary care

Developmental Markers of Genetic Liability to Autism in Parents: A Longitudinal, Multigenerational Study

Genetic liability to autism spectrum disorder (ASD) can be expressed in unaffected relatives through subclinical, genetically meaningful traits, or endophenotypes. This study aimed to identify developmental endophenotypes in parents of individuals with ASD by examining parents' childhood academic development over the school-age period. A cohort of 139 parents of individuals with ASD were studied, along with their children with ASD and 28 controls. Parents' childhood records in the domains of language, reading, and math were studied from grades K-12. Results indicated that relatively lower performance and slower development of skills (particularly language related skills), and an uneven rate of development across domains predicted ASD endophenotypes in adulthood for parents, and the severity of clinical symptoms in children with ASD. These findings may mark childhood indicators of genetic liability to ASD in parents, that could inform understanding of the subclinical expression of AS

Developmental profiles of infants with an FMR1 premutation

Abstract Background Emerging evidence suggests that a subset of FMR1 premutation carriers is at an increased risk for cognitive, emotional, and medical conditions. However, because the premutation is rarely diagnosed at birth, the early developmental trajectories of children with a premutation are not known. Methods This exploratory study examined the cognitive, communication, and social-behavioral profiles of 26 infants with a premutation who were identified through participation in a newborn screening for fragile X syndrome pilot study. In this study, families whose newborn screened positive for an FMR1 premutation were invited to participate in a longitudinal study of early development. Twenty-six infants with the premutation and 21 matched, screen-negative comparison babies were assessed using validated standardized measures at 6-month intervals starting as young as 3 months of age. The babies were assessed up to seven times over a 4-year period. Results The premutation group was not statistically different from the comparison group on measures of cognitive development, adaptive behavior, temperament, or overall communication. However, the babies with the premutation had a significantly different developmental trajectory on measures of nonverbal communication and hyperresponsivity to sensory experiences. They also were significantly more hyporesponsive at all ages than the comparison group. Cytosine-guanine-guanine repeat length was linearly associated with overall cognitive development. Conclusions These results suggest that infants with a premutation may present with subtle developmental differences as young as 12 months of age that may be early markers of later anxiety, social deficits, or other challenges thought to be experienced by a subset of carriers

Expressive morphosyntax in boys with Fragile X syndrome with and without autism spectrum disorder

Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability, and the most common single gene disorder associated with autism. Language impairments in this disorder are well documented, but the nature and extent of syntactic impairments are still unclear

The Cosmic No-Hair Theorem and the Nonlinear Stability of Homogeneous Newtonian Cosmological Models

The validity of the cosmic no-hair theorem is investigated in the context of Newtonian cosmology with a perfect fluid matter model and a positive cosmological constant. It is shown that if the initial data for an expanding cosmological model of this type is subjected to a small perturbation then the corresponding solution exists globally in the future and the perturbation decays in a way which can be described precisely. It is emphasized that no linearization of the equations or special symmetry assumptions are needed. The result can also be interpreted as a proof of the nonlinear stability of the homogeneous models. In order to prove the theorem we write the general solution as the sum of a homogeneous background and a perturbation. As a by-product of the analysis it is found that there is an invariant sense in which an inhomogeneous model can be regarded as a perturbation of a unique homogeneous model. A method is given for associating uniquely to each Newtonian cosmological model with compact spatial sections a spatially homogeneous model which incorporates its large-scale dynamics. This procedure appears very natural in the Newton-Cartan theory which we take as the starting point for Newtonian cosmology.Comment: 16 pages, MPA-AR-94-

Small data global existence for the semilinear wave equation with space-time dependent damping

In this paper we consider the critical exponent problem for the semilinear wave equation with space-time dependent damping. When the damping is effective, it is expected that the critical exponent agrees with that of only space dependent coefficient case. We shall prove that there exists a unique global solution for small data if the power of nonlinearity is larger than the expected exponent. Moreover, we do not assume that the data are compactly supported. However, it is still open whether there exists a blow-up solution if the power of nonlinearity is smaller than the expected exponent

Predictors of Parent Responsiveness to 1-Year-Olds At-Risk for Autism Spectrum Disorder

Parent responsiveness is critical for child development of cognition, social-communication, and self-regulation. Parents tend to respond more frequently when children at-risk for autism spectrum disorder (ASD) demonstrate stronger social-communication; however, it is unclear how responsiveness is associated with sensory characteristics of children at-risk for ASD. To address this issue, we examined the extent to which child social-communication and sensory reactivity patterns (i.e., hyper- and hypo-reactivity) predicted parent responsiveness to 1-year-olds at-risk for ASD in a community sample of 97 parent-infant pairs. A combination of child social-communication and sensory hypo-reactivity consistently predicted how parents played and talked with their 1-year-old at-risk for ASD. Parents tended to talk less and use more play actions when infants communicated less and demonstrated stronger hypo-reactivity