A class of nonlocal coupled semilinear parabolic system with nonlocal boundaries.
Ontology highlight
ABSTRACT:
SUBMITTER: Liu H
PROVIDER: S-EPMC3947733 | biostudies-other | 2014
REPOSITORIES: biostudies-other
Similar Datasets
Project description:We describe a novel conservative algorithm for parabolic problems in domains with moving boundaries developed for modeling in cell biology. The spatial discretization is accomplished by applying Voronoi decomposition to a fixed rectangular grid. In the vicinity of the boundary, the procedure generates irregular Voronoi cells that conform to the domain shape and merge seamlessly with regular control volumes in the domain interior. Consequently, our algorithm is free of the CFL stability issue due to moving interfaces and does not involve cell-merging or mass redistribution. Local mass conservation is ensured by finite-volume discretization and natural-neighbor interpolation. Numerical experiments with two-dimensional geometries demonstrate exact mass conservation and indicate an order of convergence in space between one and two. The use of standard meshing techniques makes extension of the method to three dimensions conceptually straightforward.
| S-EPMC4107334 | biostudies-literature
Project description:In this paper, we study a class of fourth-order parabolic equation with the logarithmic nonlinearity. By using the potential well method, we obtain the existence of the unique global weak solution. In addition, we also obtain results of decay and blow-up in the finite time for the weak solution.
| S-EPMC6267419 | biostudies-other
Project description:The stability and resilience of the Earth system and human well-being are inseparably linked1-3, yet their interdependencies are generally under-recognized; consequently, they are often treated independently4,5. Here, we use modelling and literature assessment to quantify safe and just Earth system boundaries (ESBs) for climate, the biosphere, water and nutrient cycles, and aerosols at global and subglobal scales. We propose ESBs for maintaining the resilience and stability of the Earth system (safe ESBs) and minimizing exposure to significant harm to humans from Earth system change (a necessary but not sufficient condition for justice)4. The stricter of the safe or just boundaries sets the integrated safe and just ESB. Our findings show that justice considerations constrain the integrated ESBs more than safety considerations for climate and atmospheric aerosol loading. Seven of eight globally quantified safe and just ESBs and at least two regional safe and just ESBs in over half of global land area are already exceeded. We propose that our assessment provides a quantitative foundation for safeguarding the global commons for all people now and into the future.
| S-EPMC10322705 | biostudies-literature
Project description:ObjectiveExamine care integration-efforts to unify disparate parts of health care organizations to generate synergy across activities occurring within and between them-to understand whether and at which organizational level health systems impact care quality and staff experience.Data sourcesSurveys administered to one practice manager (56/59) and up to 26 staff (828/1360) in 59 practice sites within 24 physician organizations within 17 health systems in four states (2017-2019).Study designWe developed manager and staff surveys to collect data on organizational, social, and clinical process integration, at four organizational levels: practice site, physician organization, health system, and outside health systems. We analyzed data using descriptive statistics and regression.Principal findingsManagers and staff perceived opportunity for improvement across most types of care integration and organizational levels. Managers/staff perceived little variation in care integration across health systems. They perceived better care integration within practice sites than within physician organizations, health systems, and outside health systems-up to 38 percentage points (pp) lower (P < .001) outside health systems compared to within practice sites. Of nine clinical process integration measures, one standard deviation (SD) (7.2-pp) increase in use of evidence-based care related to 6.4-pp and 8.9-pp increases in perceived quality of care by practice sites and health systems, respectively, and a 4.5-pp increase in staff job satisfaction; one SD (9.7-pp) increase in integration of social services and community resources related to a 7.0-pp increase in perceived quality of care by health systems; one SD (6.9-pp) increase in patient engagement related to a 6.4-pp increase in job satisfaction and a 4.6-pp decrease in burnout; and one SD (10.6-pp) increase in integration of diabetic eye examinations related to a 5.5-pp increase in job satisfaction (all P < .05).ConclusionsMeasures of clinical process integration related to higher staff ratings of quality and experience. Action is needed to improve care integration within and outside health systems.
| S-EPMC7720712 | biostudies-literature
Project description:The properties of topological systems are inherently tied to their dimensionality. Indeed, higher-dimensional periodic systems exhibit topological phases not shared by their lower-dimensional counterparts. On the other hand, aperiodic arrays in lower-dimensional systems (e.g., the Harper model) have been successfully employed to emulate higher-dimensional physics. This raises a general question on the possibility of extended topological classification in lower dimensions, and whether the topological invariants of higher-dimensional periodic systems may assume a different meaning in their lower-dimensional aperiodic counterparts. Here, we demonstrate that, indeed, for a topological system in higher dimensions one can construct a one-dimensional (1D) deterministic aperiodic counterpart which retains its spectrum and topological characteristics. We consider a four-dimensional (4D) quantized hexadecapole higher-order topological insulator (HOTI) which supports topological corner modes. We apply the Lanczos transformation and map it onto an equivalent deterministic aperiodic 1D array (DAA) emulating 4D HOTI in 1D. We observe topological zero-energy zero-dimensional (0D) states of the DAA-the direct counterparts of corner states in 4D HOTI and the hallmark of the multipole topological phase, which is meaningless in lower dimensions. To explain this paradox, we show that higher-dimension invariant, the multipole polarization, retains its quantization in the DAA, yet changes its meaning by becoming a nonlocal correlator in the 1D system. By introducing nonlocal topological phases of DAAs, our discovery opens a direction in topological physics. It also unveils opportunities to engineer topological states in aperiodic systems and paves the path to application of resonances associates with such states protected by nonlocal symmetries.
| S-EPMC8403875 | biostudies-literature
Project description:Explaining observations in terms of causes and effects is central to empirical science. However, correlations between entangled quantum particles seem to defy such an explanation. This implies that some of the fundamental assumptions of causal explanations have to give way. We consider a relaxation of one of these assumptions, Bell's local causality, by allowing outcome dependence: a direct causal influence between the outcomes of measurements of remote parties. We use interventional data from a photonic experiment to bound the strength of this causal influence in a two-party Bell scenario, and observational data from a Bell-type inequality test for the considered models. Our results demonstrate the incompatibility of quantum mechanics with a broad class of nonlocal causal models, which includes Bell-local models as a special case. Recovering a classical causal picture of quantum correlations thus requires an even more radical modification of our classical notion of cause and effect.
| S-EPMC4980107 | biostudies-literature
Project description:Previous studies suggest that altered gravity levels during parabolic flight maneuvers affect spatial updating. Little is known about the impact of the experimental setting and psychological stressors associated with parabolic flight experiments on attentional processes. To address this gap, we investigated the level of alertness, selective and sustained attention in 1 and 0 g using a Go/No-Go Continuous Performance Task. We also identified several parameters associated with the experimental set-up of a parabolic flight that could be expected to affect attentional processing. These included the use of scopolamine, sleep quality prior to the flight day, participant's stress level as well as mood and anxiety state before and after the parabolic flight. We observed a deterioration in attentional processing prior to the first parabola that was further aggravated in weightlessness and returned to baseline after the last parabola. Reaction Time, Hit and False Alarm Rate were moderately correlated with self-reported anxiety state, but not cortisol levels or emotional states. The use of scopolamine had minor effects on Reaction Time. Our results confirm previous studies reporting impairments of cognitive performance in 0 g, and highlight important aspects that should be considered for the design of behavioral research experiments in future parabolic flight campaigns.
| S-EPMC8155259 | biostudies-literature
Project description:G protein-coupled receptors (GPCRs) are a large superfamily of membrane bound signaling proteins that hold great pharmaceutical interest. Since experimentally elucidated structures are available only for a very limited number of receptors, homology modeling has become a widespread technique for the construction of GPCR models intended to study the structure-function relationships of the receptors and aid the discovery and development of ligands capable of modulating their activity. Through this chapter, various aspects involved in the constructions of homology models of the serpentine domain of the largest class of GPCRs, known as class A or rhodopsin family, are illustrated. In particular, the chapter provides suggestions, guidelines, and critical thoughts on some of the most crucial aspect of GPCR modeling, including: collection of candidate templates and a structure-based alignment of their sequences; identification and alignment of the transmembrane helices of the query receptor to the corresponding domains of the candidate templates; selection of one or more templates receptor; election of homology or de novo modeling for the construction of specific extracellular and intracellular domains; construction of the 3D models, with special consideration to extracellular regions, disulfide bridges, and interhelical cavity; validation of the models through controlled virtual screening experiments.
| S-EPMC3354613 | biostudies-literature
Project description:Epithelial cells dynamically self-organize in response to extracellular spatial cues relayed by cell-surface receptors. During convergent extension in Drosophila, Toll-related receptors direct planar polarized cell rearrangements that elongate the head-to-tail axis. However, many cells establish polarity in the absence of Toll receptor activity, indicating the presence of additional spatial cues. Here we demonstrate that the leucine-rich-repeat receptor Tartan and the teneurin Ten-m provide critical polarity signals at epithelial compartment boundaries. The Tartan and Ten-m extracellular domains interact in vitro, and Tartan promotes Ten-m localization to compartment boundaries in vivo. We show that Tartan and Ten-m are necessary for the planar polarity and organization of compartment boundary cells. Moreover, ectopic stripes of Tartan and Ten-m are sufficient to induce myosin accumulation at stripe boundaries. These results demonstrate that the Tartan/Ten-m and Toll receptor systems together create a high-resolution network of spatial cues that guides cell behavior during convergent extension.
| S-EPMC8415256 | biostudies-literature
Project description:In a 2-alternative forced-choice protocol, observers judged the duration of ball motions shown on an immersive virtual-reality display as approaching in the sagittal plane along parabolic trajectories compatible with Earth gravity effects. In different trials, the ball shifted along the parabolas with one of three different laws of motion: constant tangential velocity, constant vertical velocity, or gravitational acceleration. Only the latter motion was fully consistent with Newton's laws in the Earth gravitational field, whereas the motions with constant velocity profiles obeyed the spatio-temporal constraint of parabolic paths dictated by gravity but violated the kinematic constraints. We found that the discrimination of duration was accurate and precise for all types of motions, but the discrimination for the trajectories at constant tangential velocity was slightly but significantly more precise than that for the trajectories at gravitational acceleration or constant vertical velocity. The results are compatible with a heuristic internal representation of gravity effects that can be engaged when viewing projectiles shifting along parabolic paths compatible with Earth gravity, irrespective of the specific kinematics. Opportunistic use of a moving frame attached to the target may favour visual tracking of targets with constant tangential velocity, accounting for the slightly superior duration discrimination.
| S-EPMC8007634 | biostudies-literature