127 research outputs found
The Relationship between Behavioural Changes, Cognitive Symptoms, and Functional Disability in Primary Progressive Aphasia: A Longitudinal Study
Background: The contribution of behavioural changes to functional decline is yet to be explored in primary progressive aphasia (PPA). Objectives: (1) investigate functional changes in two PPA variants [semantic (svPPA) and non-fluent (nfvPPA)], at baseline and after 12 months; (2) investigate baseline differences in behavioural changes between groups, and (3) explore predictors of functional decline after a 12-month period. Methods: A longitudinal study involving 29 people with PPA (18 svPPA; 11 nfvPPA) seen annually in Sydney/Australia was conducted. A total of 114 functional and behavioural assessments were included for within-group (repeated-measures ANOVA; annual rate of change; multiple regression analyses) and between-group analyses (pairwise comparisons). Results: Functional profiles in svPPA and nfvPPA were similar in people with up to 5 years of disease duration. Behavioural changes were marked in svPPA patients (stereotypical behaviour and apathy) but did not predict annual rate of change of functional abilities; global cognitive scores at baseline did. Despite mild behavioural changes in nfvPPA (disinhibition, apathy), these were significant predictors of annual rate of functional change. Conclusions: The presentation and interplay of behavioural changes and functional disability differ in svPPA and nfvPPA. These varying factors should be taken into account when considering prognosis, disease management, and selection of outcome measures for interventions
Statistics of Lyapunov exponent in one-dimensional layered systems
Localization of acoustic waves in a one dimensional water duct containing
many randomly distributed air filled blocks is studied. Both the Lyapunov
exponent and its variance are computed. Their statistical properties are also
explored extensively. The results reveal that in this system the single
parameter scaling is generally inadequate no matter whether the frequency we
consider is located in a pass band or in a band gap. This contradicts the
earlier observations in an optical case. We compare the results with two
optical cases and give a possible explanation of the origin of the different
behaviors.Comment: 6 pages revtex file, 6 eps figure
A comparison of infant and toddler feeding practices of mothers with and without histories of eating disorders
This preliminary study surveyed the feeding practices of mothers with eating disorder histories through evaluation of mothers' reported feeding styles, child diet composition and restrictive special approaches to feeding. For this non-randomised cohort study, 25 mothers with eating disorder histories and 25 mothers with no history of an eating disorder with children ages 6-36 months were selected such that the groups were similar based on child age group and child sex. Mothers were compared on self-reported feeding style using the Infant Feeding Styles Questionnaire and on child diet composition and special feeding approaches using a modified version of the Toddler Diet Questionnaire from the Women, Infants, and Children program. Mothers with eating disorder histories scored lower on the restrictive feeding style subscale than controls. No significant differences were detected between groups in child diet including the percentage of mothers who breastfed, duration of breastfeeding, age at solid food introduction, daily number of meals or snacks or daily frequency of consumption of fruits, vegetables or protein foods. Mothers with eating disorder histories were more likely to report taking a restrictive special approach to feeding such as limiting processed foods or feeding organic foods only. Although mothers with eating disorder histories may not differ greatly from control mothers in terms of child diet composition (smaller effects may not have been detected due to limited sample size), they may be more likely to take restrictive special approaches to feeding which mirror dietary rules common in individuals with eating disorders
Family-based obesity prevention for infants: Design of the âMothers & Othersâ randomized trial
Objective Our goal is to test the efficacy of a family-based, multi-component intervention focused on infants of African-American (AA) mothers and families, a minority population at elevated risk for pediatric obesity, versus a child safety attention-control group to promote healthy weight gain patterns during the first two years of life. Design, participants, and methods The design is a two-group randomized controlled trial among 468 AA pregnant women in central North Carolina. Mothers and study partners in the intervention group receive anticipatory guidance on breastfeeding, responsive feeding, use of non-food soothing techniques for infant crying, appropriate timing and quality of complementary feeding, age-appropriate infant sleep, and minimization of TV/media. The primary delivery channel is 6 home visits by a peer educator, 4 interim newsletters and twice-weekly text messaging. Intervention families also receive 2 home visits from an International Board Certified Lactation Consultant. Assessments occur at 28 and 37 weeks gestation and when infants are 1, 3, 6, 9, 12, and 15 months of age. Results The primary outcome is infant/toddler growth and likelihood of overweight at 15 months. Differences between groups are expected to be achieved through uptake of the targeted infant feeding and care behaviors (secondary outcomes) and change in caregivers' modifiable risk factors (mediators) underpinning the intervention. Conclusions If successful in promoting healthy infant growth and enhancing caregiver behaviors, âMothers and Othersâ will have high public health relevance for future obesity-prevention efforts aimed at children younger than 2 years, including interventional research and federal, state, and community health programs. Trial Registration ClinicalTrials.gov, NCT01938118, August 9, 2013
Magnetic Order in YBaCuO Superconductors
Polarized and unpolarized neutron diffraction has been used to search for
magnetic order in YBaCuO superconductors. Most of the
measurements were made on a high quality crystal of YBaCuO. It
is shown that this crystal has highly ordered ortho-II chain order, and a sharp
superconducting transition. Inelastic scattering measurements display a very
clean spin-gap and pseudogap with any intensity at 10 meV being 50 times
smaller than the resonance intensity. The crystal shows a complicated magnetic
order that appears to have three components. A magnetic phase is found at high
temperatures that seems to stem from an impurity with a moment that is in the
- plane, but disordered on the crystal lattice. A second ordering occurs
near the pseudogap temperature that has a shorter correlation length than the
high temperature phase and a moment direction that is at least partly along the
c-axis of the crystal. Its moment direction, temperature dependence, and Bragg
intensities suggest that it may stem from orbital ordering of the -density
wave (DDW) type. An additional intensity increase occurs below the
superconducting transition. The magnetic intensity in these phases does not
change noticeably in a 7 Tesla magnetic field aligned approximately along the
c-axis. Searches for magnetic order in YBaCuO show no signal
while a small magnetic intensity is found in YBaCuO that is
consistent with c-axis directed magnetic order. The results are contrasted with
other recent neutron measurements.Comment: 11 pages with 10 figure
Inflationary perturbations from a potential with a step
We use a numerical code to compute the density perturbations generated during
an inflationary epoch which includes a spontaneous symmetry breaking phase
transition. A sharp step in the inflaton potential generates dependent
oscillations in the spectrum of primordial density perturbations. The amplitude
and extent in wavenumber of these oscillations depends on both the magnitude
and gradient of the step in the inflaton potential. We show that observations
of the cosmic microwave background anisotropy place strong constraints on the
step parameters.Comment: 6 pages, Revtex - v2. reference adde
Diffusive and localization behavior of electromagnetic waves in a two-dimensional random medium
In this paper, we discuss the transport phenomena of electromagnetic waves in
a two-dimensional random system which is composed of arrays of electrical
dipoles, following the model presented earlier by Erdogan, et al. (J. Opt. Soc.
Am. B {\bf 10}, 391 (1993)). A set of self-consistent equations is presented,
accounting for the multiple scattering in the system, and is then solved
numerically. A strong localization regime is discovered in the frequency
domain. The transport properties within, near the edge of and nearly outside
the localization regime are investigated for different parameters such as
filling factor and system size. The results show that within the localization
regime, waves are trapped near the transmitting source. Meanwhile, the
diffusive waves follow an intuitive but expected picture. That is, they
increase with travelling path as more and more random scattering incurs,
followed by a saturation, then start to decay exponentially when the travelling
path is large enough, signifying the localization effect. For the cases that
the frequencies are near the boundary of or outside the localization regime,
the results of diffusive waves are compared with the diffusion approximation,
showing less encouraging agreement as in other systems (Asatryan, et al., Phys.
Rev. E {\bf 67}, 036605 (2003).)Comment: 8 pages 9 figure
New insights into bacterial chemoreceptor array structure and assembly from electron cryotomography
FWN â Publicaties zonder aanstelling Universiteit Leide
On the violation of the Fermi-liquid picture in two-dimensional systems owing to the Van-Hove singularities
We consider the two-dimensional t-t' Hubbard model with the Fermi level being
close to the van Hove singularities. The phase diagram of the model is
discussed. In a broad energy region the self-energy at the singularity points
has a nearly-linear energy dependence. The corresponding correction to the
density of states is proportional to ln^3(e). Both real- and imaginary part of
the self-energy increase near the quantum phase transition into magnetically
ordered or superconducting phase which implies violation of the Fermi-liquid
behavior. The application of the results to cuprates is discussed.Comment: 16 pages, RevTeX, 5 figures; The errors of the published version (PRB
64, 205105, 2001) are correcte
A review of spatial causal inference methods for environmental and epidemiological applications
The scientific rigor and computational methods of causal inference have had
great impacts on many disciplines, but have only recently begun to take hold in
spatial applications. Spatial casual inference poses analytic challenges due to
complex correlation structures and interference between the treatment at one
location and the outcomes at others. In this paper, we review the current
literature on spatial causal inference and identify areas of future work. We
first discuss methods that exploit spatial structure to account for unmeasured
confounding variables. We then discuss causal analysis in the presence of
spatial interference including several common assumptions used to reduce the
complexity of the interference patterns under consideration. These methods are
extended to the spatiotemporal case where we compare and contrast the potential
outcomes framework with Granger causality, and to geostatistical analyses
involving spatial random fields of treatments and responses. The methods are
introduced in the context of observational environmental and epidemiological
studies, and are compared using both a simulation study and analysis of the
effect of ambient air pollution on COVID-19 mortality rate. Code to implement
many of the methods using the popular Bayesian software OpenBUGS is provided
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