Browsing by Subject "complexity"

Now showing 1 - 4 of 4
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    A Systematic Review of Conceptual Frameworks of Medical Complexity and New Model Development.
    (J Gen Intern Med, 2016-03) Zullig, Leah L; Whitson, Heather E; Hastings, Susan N; Beadles, Chris; Kravchenko, Julia; Akushevich, Igor; Maciejewski, Matthew L
    BACKGROUND: Patient complexity is often operationalized by counting multiple chronic conditions (MCC) without considering contextual factors that can affect patient risk for adverse outcomes. OBJECTIVE: Our objective was to develop a conceptual model of complexity addressing gaps identified in a review of published conceptual models. DATA SOURCES: We searched for English-language MEDLINE papers published between 1 January 2004 and 16 January 2014. Two reviewers independently evaluated abstracts and all authors contributed to the development of the conceptual model in an iterative process. RESULTS: From 1606 identified abstracts, six conceptual models were selected. One additional model was identified through reference review. Each model had strengths, but several constructs were not fully considered: 1) contextual factors; 2) dynamics of complexity; 3) patients' preferences; 4) acute health shocks; and 5) resilience. Our Cycle of Complexity model illustrates relationships between acute shocks and medical events, healthcare access and utilization, workload and capacity, and patient preferences in the context of interpersonal, organizational, and community factors. CONCLUSIONS/IMPLICATIONS: This model may inform studies on the etiology of and changes in complexity, the relationship between complexity and patient outcomes, and intervention development to improve modifiable elements of complex patients.
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    SMALL-SIZE epsilon-NETS FOR AXIS-PARALLEL RECTANGLES AND BOXES
    (2010) Aronov, Boris; Ezra, Esther; Sharir, Micha
    We show the existence of epsilon-nets of size O (1/epsilon log log 1/epsilon) for planar point sets and axis-parallel rectangular ranges. The same bound holds for points in the plane and "fat" triangular ranges and for point sets in R-3 and axis-parallel boxes; these are the first known nontrivial bounds for these range spaces. Our technique also yields improved bounds on the size of epsilon-nets in the more general context considered by Clarkson and Varadarajan. For example, we show the existence of epsilon-nets of size O (1/epsilon log log log 1/epsilon) for the dual range space of "fat" regions and planar point sets (where the regions are the ground objects and the ranges are subsets stabbed by points). Plugging our bounds into the technique of Bronnimann and Goodrich or of Even, Rawitz, and Shahar, we obtain improved approximation factors (computable in expected polynomial time by a randomized algorithm) for the HITTING SET or the SET COVER problems associated with the corresponding range spaces.
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    Spontaneous brain activity as a source of ideal 1/f noise
    (2009) Allegrini, Paolo; Menicucci, Danilo; Bedini, Remo; Fronzoni, Leone; Gemignani, Angelo; Grigolini, Paolo; West, Bruce J; Paradisi, Paolo
    We study the electroencephalogram (EEG) of 30 closed-eye awake subjects with a technique of analysis recently proposed to detect punctual events signaling rapid transitions between different metastable states. After single-EEG-channel event detection, we study global properties of events simultaneously occurring among two or more electrodes termed coincidences. We convert the coincidences into a diffusion process with three distinct rules that can yield the same mu only in the case where the coincidences are driven by a renewal process. We establish that the time interval between two consecutive renewal events driving the coincidences has a waiting-time distribution with inverse power-law index mu approximate to 2 corresponding to ideal 1/f noise. We argue that this discovery, shared by all subjects of our study, supports the conviction that 1/f noise is an optimal communication channel for complex networks as in art or language and may therefore be the channel through which the brain influences complex processes and is influenced by them.
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    To plasticity and back again.
    (Elife, 2015-03-12) Nijhout, H Frederik
    Both the gain and the loss of flexibility in the development of phenotypes have led to an increased diversity of physical forms in nematode worms.