232 research outputs found
Effects of Non-Local Diffusion on Structural MRI Preprocessing and Default Network Mapping: Statistical Comparisons with Isotropic/Anisotropic Diffusion
Neuroimaging community usually employs spatial smoothing to denoise magnetic resonance imaging (MRI) data, e.g., Gaussian smoothing kernels. Such an isotropic diffusion (ISD) based smoothing is widely adopted for denoising purpose due to its easy implementation and efficient computation. Beyond these advantages, Gaussian smoothing kernels tend to blur the edges, curvature and texture of images. Researchers have proposed anisotropic diffusion (ASD) and non-local diffusion (NLD) kernels. We recently demonstrated the effect of these new filtering paradigms on preprocessing real degraded MRI images from three individual subjects. Here, to further systematically investigate the effects at a group level, we collected both structural and functional MRI data from 23 participants. We first evaluated the three smoothing strategies' impact on brain extraction, segmentation and registration. Finally, we investigated how they affect subsequent mapping of default network based on resting-state functional MRI (R-fMRI) data. Our findings suggest that NLD-based spatial smoothing maybe more effective and reliable at improving the quality of both MRI data preprocessing and default network mapping. We thus recommend NLD may become a promising method of smoothing structural MRI images of R-fMRI pipeline
Fairy circles reveal the resilience of self-organized salt marshes
Spatial patterning is a fascinating theme in both theoretical and experimental ecology. It reveals resilience and stability to withstand external disturbances and environmental stresses. However, existing studies mainly focus on well-developed persistent patterns rather than transient patterns in self-organizing ecosystems. Here, combining models and experimental evidence, we show that transient fairy circle patterns in intertidal salt marshes can both infer the underlying ecological mechanisms and provide a measure of resilience. The models based on sulfide accumulation and nutrient depletion mechanisms reproduced the field-observed fairy circles, providing a generalized perspective on the emergence of transient patterns in salt marsh ecosystems. Field experiments showed that nitrogen fertilization mitigates depletion stress and shifts plant growth from negative to positive in the center of patches. Hence, nutrient depletion plays an overriding role, as only this process can explain the concentric rings. Our findings imply that the emergence of transient patterns can identify the ecological processes underlying pattern formation and the factors determining the ecological resilience of salt marsh ecosystems
Bis{(E)-2-[1-(ethoxyimino)ethyl]-1-naphtholato-κ2 N,O 1}copper(II)
In the title complex, [Cu(C14H14NO2)2], the discrete complex molecules have crystallographic inversion symmetry. The slightly distorted square-planar coordination sphere of the CuII atom comprises two phenolate O atoms and two oxime N atoms from two bidentate–chelate 2-[1-(ethoxyimino)ethyl]-1-naphtholate O-ethyl oxime (L
−) ligands [Cu—O = 1.8919 (17) Å and Cu—N = 1.988 (2) Å]. The two naphthalene ring systems in the molecule are parallel, with a perpendicular interplanar spacing of 1.473 (2) Å, while each complex unit forms links to four other molecules via intermolecular methyl C—H⋯π interactions, giving an infinite cross-linked layered supramolecular structur
Public Company Health Insurers and Medical Loss Ratios: An Event Study of Dates Associated with the Affordable Care Act
The Affordable Care Act (ACA) has proved to be a contentious regulatory and political topic. Although key features were established within the law the complexity of the new provisions and political opposition resulted in a series of federal and state governmental process changes, rule clarifications, and legal challenges. One component of the ACA is the introduction of a federal Medical Loss Ratio (MLR), which requires insurers to spend specified percentages of their premium revenue dollars on medical services and quality improvement actions. If thresholds are not met, insurers must refund premiums to their members, potentially removing millions of dollars from their operating income in any given year. This research uses event study methodology to examine share price fluctuations for publicly traded health insurers to understand the relationship between legislative and regulatory events associated with the establishment of the ACA and the federal MLR requirements. Regulatory developments in aggregate were found to be associated with slightly positive changes in share prices. Legislative events in aggregate were not associated with a significant change in share prices for publicly traded health insurers. Upon closer investigation, the initial draft of ACA legislation produced by the HELP Committee and sent to the Congressional Budget Office on June 9, 2009, including federal MLR requirements, was associated with a significant negative change in share prices for publicly traded health insurers
Effectiveness of a kindergarten-based intervention for preventing childhood obesity
BACKGROUND AND OBJECTIVES:Interventions to prevent childhood obesity targeting school age children have mostly reported limited effectiveness, suggesting such prevention programs may need to start at an earlier age, but evidence has been scarce. We reported a pilot study aiming to demonstrate the feasibility of a multifaceted intervention for preschool children and to provide a preliminary assessment of the effectiveness.METHODS:This nonrandomized controlled trial recruited children aged 3 to 6 years from 6 kindergartens in Guangzhou, China. Based on the preference of the School and Parents Committees, 4 kindergartens (648 children) received a 3-component intervention (training of kindergarten staff, initiating healthy curriculum for children, and close collaboration between families and kindergartens) over 12 months, while the other 2 kindergartens (336 children), serving as controls, received routine health care provision. Outcome measures were the changes in BMI z score between baseline and the end of 12 months, and the prevalence of postintervention children who were overweight or obese.RESULTS:By 12 months, children within the intervention group had a smaller BMI z score increase (0.24) compared to the control (0.41), with a difference of –0.31 (95% CI –0.47 to –0.15). The prevalence of overweight or obesity was also lower among the intervention group at the end of the study (OR: 0.43, 95% CI 0.19 to 0.96), adjusted for baseline status.CONCLUSIONS:Our results indicated a multicomponent health behavior intervention might be effective in reducing the prevalence of obesity, but the longer term effects will need confirmation from randomized controlled trials.</jats:sec
DREAM: A Toolbox to Decode Rhythms of the Brain System
Rhythms of the brain are generated by neural oscillations across multiple frequencies. These oscillations can be decomposed into distinct frequency intervals associated with specific physiological processes. In practice, the number and ranges of decodable frequency intervals are determined by sampling parameters, often ignored by researchers. To improve the situation, we report on an open toolbox with a graphical user interface for decoding rhythms of the brain system (DREAM). We provide worked examples of DREAM to investigate frequency-specific performance of both neural (spontaneous brain activity) and neurobehavioral (in-scanner head motion) oscillations. DREAM decoded the head motion oscillations and uncovered that younger children moved their heads more than older children across all five frequency intervals whereas boys moved more than girls in the age of 7 to 9 years. It is interesting that the higher frequency bands contain more head movements,
Measurement of proton electromagnetic form factors in in the energy region 2.00-3.08 GeV
The process of is studied at 22 center-of-mass
energy points () from 2.00 to 3.08 GeV, exploiting 688.5~pb of
data collected with the BESIII detector operating at the BEPCII collider. The
Born cross section~() of is
measured with the energy-scan technique and it is found to be consistent with
previously published data, but with much improved accuracy. In addition, the
electromagnetic form-factor ratio () and the value of the
effective (), electric () and magnetic () form
factors are measured by studying the helicity angle of the proton at 16
center-of-mass energy points. and are determined with
high accuracy, providing uncertainties comparable to data in the space-like
region, and is measured for the first time. We reach unprecedented
accuracy, and precision results in the time-like region provide information to
improve our understanding of the proton inner structure and to test theoretical
models which depend on non-perturbative Quantum Chromodynamics
First observations of hadrons
Based on events collected with
the BESIII detector, five hadronic decays are searched for via process
. Three of them, ,
, and are observed for the first
time, with statistical significances of 7.4, , and
9.1, and branching fractions of ,
, and ,
respectively, where the first uncertainties are statistical and the second
systematic. No significant signal is observed for the other two decay modes,
and the corresponding upper limits of the branching fractions are determined to
be and at 90% confidence level.Comment: 17 pages, 16 figure
Measurements of Weak Decay Asymmetries of , , , and
Using production from a 567 pb
data sample collected by BESIII at 4.6 GeV, a full angular analysis is carried
out simultaneously on the four decay modes of , , , and . For the first time, the
transverse polarization is studied in unpolarized
collisions, where a non-zero effect is observed with a statistical significance
of 2.1. The decay asymmetry parameters of the weak
hadronic decays into , , and
are measured to be ,
,
, and
, respectively. In comparison with
previous results, the measurements for the and
modes are consistent but with improved precision, while the parameters for the
and modes are measured for the first time
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