3,448 research outputs found
The impact of coping and resilience on anxiety among older Australians
Objective: This study aims to explore the relationships between various coping types, resilience, and anxiety among older Australians. Particular attention is paid to whether resilience moderates coping’s effect on anxiety.
Method: A total of 324 Australians aged between 55 and 90 (M = 66.7, SD = 8.6) were surveyed as part of the study. Moderation was assessed using structural equation modelling and plots of simple slopes.
Results: Significant negative correlations were detected between anxiety and both proactive coping and preventive coping. Higher levels of resilience were associated with lower levels of anxiety. Age moderated both proactive coping and reflective coping's effects on anxiety and gender moderated avoidance coping’s effect on anxiety. Resilience was found to moderate the relationships between proactive coping and anxiety, and instrumental support seeking and anxiety. For those high in resilience, there was little association between anxiety and proactive coping or anxiety and instrumental support seeking. Among low resilience individuals, there was a negative association between proactive coping and anxiety, but a positive association between instrumental support seeking and anxiety.
Conclusion: Resilience, proactive coping, and preventive coping are all important predictors of anxiety among older people. Among those who are low in resilience, proactively coping with stress may be particularly important for good mental health. The results of the study highlight the complexity of the relationship between resilience, coping, and anxiety among older people
Analytical method to measure three-dimensional strain patterns in the left ventricle from single slice displacement data
Background:
Displacement encoded Cardiovascular MR (CMR) can provide high spatial resolution measurements of three-dimensional (3D) Lagrangian displacement. Spatial gradients of the Lagrangian displacement field are used to measure regional myocardial strain. In general, adjacent parallel slices are needed in order to calculate the spatial gradient in the through-slice direction. This necessitates the acquisition of additional data and prolongs the scan time. The goal of this study is to define an analytic solution that supports the reconstruction of the out-of-plane components of the Lagrangian strain tensor in addition to the in-plane components from a single-slice displacement CMR dataset with high spatio-temporal resolution. The technique assumes incompressibility of the myocardium as a physical constraint.
Results:
The feasibility of the method is demonstrated in a healthy human subject and the results are compared to those of other studies. The proposed method was validated with simulated data and strain estimates from experimentally measured DENSE data, which were compared to the strain calculation from a conventional two-slice acquisition.
Conclusion:
This analytical method reduces the need to acquire data from adjacent slices when calculating regional Lagrangian strains and can effectively reduce the long scan time by a factor of two
The Functional Convergence and Heterogeneity of Social, Episodic, and Self-Referential Thought in the Default Mode Network.
The default mode network (DMN) is engaged in a variety of cognitive settings, including social, semantic, temporal, spatial, and self-related tasks. Andrews-Hanna et al. (2010; Andrews-Hanna 2012) proposed that the DMN consists of three distinct functional-anatomical subsystems-a dorsal medial prefrontal cortex (dMPFC) subsystem that supports social cognition; a medial temporal lobe (MTL) subsystem that contributes to memory-based scene construction; and a set of midline core hubs that are especially involved in processing self-referential information. We examined activity in the DMN subsystems during six different tasks: 1) theory of mind, 2) moral dilemmas, 3) autobiographical memory, 4) spatial navigation, 5) self/other adjective judgment, and 6) a rest condition. At a broad level, we observed similar whole-brain activity maps for the six contrasts, and some response to every contrast in each of the three subsystems. In more detail, both univariate analysis and multivariate activity patterns showed partial functional separation, especially between dMPFC and MTL subsystems, though with less support for common activity across the midline core. Integrating social, spatial, self-related, and other aspects of a cognitive situation or episode, multiple components of the DMN may work closely together to provide the broad context for current mental activity
Hierarchical Representation of Multistep Tasks in Multiple-Demand and Default Mode Networks.
Task episodes consist of sequences of steps that are performed to achieve a goal. We used fMRI to examine neural representation of task identity, component items, and sequential position, focusing on two major cortical systems-the multiple-demand (MD) and default mode networks (DMN). Human participants (20 males, 22 females) learned six tasks each consisting of four steps. Inside the scanner, participants were cued which task to perform and then sequentially identified the target item of each step in the correct order. Univariate time course analyses indicated that intra-episode progress was tracked by a tonically increasing global response, plus an increasing phasic step response specific to MD regions. Inter-episode boundaries evoked a widespread response at episode onset, plus a marked offset response specific to DMN regions. Representational similarity analysis (RSA) was used to examine representation of task identity and component steps. Both networks represented the content and position of individual steps, however the DMN preferentially represented task identity while the MD network preferentially represented step-level information. Thus, although both MD and DMN networks are sensitive to step-level and episode-level information in the context of hierarchical task performance, they exhibit dissociable profiles in terms of both temporal dynamics and representational content. The results suggest collaboration of multiple brain regions in control of multistep behavior, with MD regions particularly involved in processing the detail of individual steps, and DMN adding representation of broad task context.SIGNIFICANCE STATEMENT Achieving one's goals requires knowing what to do and when. Tasks are typically hierarchical, with smaller steps nested within overarching goals. For effective, flexible behavior, the brain must represent both levels. We contrast response time courses and information content of two major cortical systems-the multiple-demand (MD) and default mode networks (DMN)-during multistep task episodes. Both networks are sensitive to step-level and episode-level information, but with dissociable profiles. Intra-episode progress is tracked by tonically increasing global responses, plus MD-specific increasing phasic step responses. Inter-episode boundaries evoke widespread responses at episode onset, plus DMN-specific offset responses. Both networks represent content and position of individual steps; however, the DMN and MD networks favor task identity and step-level information, respectively
Selection of the scaling solution in a cluster coalescence model
The scaling properties of the cluster size distribution of a system of
diffusing clusters is studied in terms of a simple kinetic mean field model. It
is shown that a one parameter family of mathematically valid scaling solutions
exists. Despite this, the kinetics reaches a unique scaling solution
independent of initial conditions. This selected scaling solution is marginally
physical; i.e., it is the borderline solution between the unphysical and
physical branches of the family of solutions.Comment: 4 pages, 5 figure
The Direct Assignment Option as a Modular Design Component: An Example for the Setting of Two Predefined Subgroups
Background. A phase II design with an option for direct assignment (stop randomization and assign all patients to experimental treatment based on interim analysis, IA) for a predefined subgroup was previously proposed. Here, we illustrate the modularity of the direct assignment option by applying it to the setting of two predefined subgroups and testing for separate subgroup main effects. Methods. We power the 2-subgroup direct assignment option design with 1 IA (DAD-1) to test for separate subgroup main effects, with assessment of power to detect an interaction in a post-hoc test. Simulations assessed the statistical properties of this design compared to the 2-subgroup balanced randomized design with 1 IA, BRD-1. Different response rates for treatment/control in subgroup 1 (0.4/0.2) and in subgroup 2 (0.1/0.2, 0.4/0.2) were considered. Results. The 2-subgroup DAD-1 preserves power and type I error rate compared to the 2-subgroup BRD-1, while exhibiting reasonable power in a post-hoc test for interaction. Conclusion. The direct assignment option is a flexible design component that can be incorporated into broader design frameworks, while maintaining desirable statistical properties, clinical appeal, and logistical simplicity
Finite-Temperature Fidelity-Metric Approach to the Lipkin-Meshkov-Glick Model
The fidelity metric has recently been proposed as a useful and elegant
approach to identify and characterize both quantum and classical phase
transitions. We study this metric on the manifold of thermal states for the
Lipkin-Meshkov-Glick (LMG) model. For the isotropic LMG model, we find that the
metric reduces to a Fisher-Rao metric, reflecting an underlying classical
probability distribution. Furthermore, this metric can be expressed in terms of
derivatives of the free energy, indicating a relation to Ruppeiner geometry.
This allows us to obtain exact expressions for the (suitably rescaled) metric
in the thermodynamic limit. The phase transition of the isotropic LMG model is
signalled by a degeneracy of this (improper) metric in the paramagnetic phase.
Due to the integrability of the isotropic LMG model, ground state level
crossings occur, leading to an ill-defined fidelity metric at zero temperature.Comment: 18 pages, 3 figure
Yeast homotypic vacuole fusion requires the Ccz1–Mon1 complex during the tethering/docking stage
The function of the yeast lysosome/vacuole is critically linked with the morphology of the organelle. Accordingly, highly regulated processes control vacuolar fission and fusion events. Analysis of homotypic vacuole fusion demonstrated that vacuoles from strains defective in the CCZ1 and MON1 genes could not fuse. Morphological evidence suggested that these mutant vacuoles could not proceed to the tethering/docking stage. Ccz1 and Mon1 form a stable protein complex that binds the vacuole membrane. In the absence of the Ccz1–Mon1 complex, the integrity of vacuole SNARE pairing and the unpaired SNARE class C Vps/HOPS complex interaction were both impaired. The Ccz1–Mon1 complex colocalized with other fusion components on the vacuole as part of the cis-SNARE complex, and the association of the Ccz1–Mon1 complex with the vacuole appeared to be regulated by the class C Vps/HOPS complex proteins. Accordingly, we propose that the Ccz1–Mon1 complex is critical for the Ypt7-dependent tethering/docking stage leading to the formation of a trans-SNARE complex and subsequent vacuole fusion
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