10 research outputs found
Thermodynamics as a theory of decision-making with information processing costs
Perfectly rational decision-makers maximize expected utility, but crucially
ignore the resource costs incurred when determining optimal actions. Here we
propose an information-theoretic formalization of bounded rational
decision-making where decision-makers trade off expected utility and
information processing costs. Such bounded rational decision-makers can be
thought of as thermodynamic machines that undergo physical state changes when
they compute. Their behavior is governed by a free energy functional that
trades off changes in internal energy-as a proxy for utility-and entropic
changes representing computational costs induced by changing states. As a
result, the bounded rational decision-making problem can be rephrased in terms
of well-known concepts from statistical physics. In the limit when
computational costs are ignored, the maximum expected utility principle is
recovered. We discuss the relation to satisficing decision-making procedures as
well as links to existing theoretical frameworks and human decision-making
experiments that describe deviations from expected utility theory. Since most
of the mathematical machinery can be borrowed from statistical physics, the
main contribution is to axiomatically derive and interpret the thermodynamic
free energy as a model of bounded rational decision-making.Comment: 26 pages, 5 figures, (under revision since February 2012
Human Cytomegalovirus IE1 Protein Elicits a Type II Interferon-Like Host Cell Response That Depends on Activated STAT1 but Not Interferon-γ
Human cytomegalovirus (hCMV) is a highly prevalent pathogen that, upon primary
infection, establishes life-long persistence in all infected individuals. Acute
hCMV infections cause a variety of diseases in humans with developmental or
acquired immune deficits. In addition, persistent hCMV infection may contribute
to various chronic disease conditions even in immunologically normal people. The
pathogenesis of hCMV disease has been frequently linked to inflammatory host
immune responses triggered by virus-infected cells. Moreover, hCMV infection
activates numerous host genes many of which encode pro-inflammatory proteins.
However, little is known about the relative contributions of individual viral
gene products to these changes in cellular transcription. We systematically
analyzed the effects of the hCMV 72-kDa immediate-early 1 (IE1) protein, a major
transcriptional activator and antagonist of type I interferon (IFN) signaling,
on the human transcriptome. Following expression under conditions closely
mimicking the situation during productive infection, IE1 elicits a global type
II IFN-like host cell response. This response is dominated by the selective
up-regulation of immune stimulatory genes normally controlled by IFN-γ and
includes the synthesis and secretion of pro-inflammatory chemokines.
IE1-mediated induction of IFN-stimulated genes strictly depends on
tyrosine-phosphorylated signal transducer and activator of transcription 1
(STAT1) and correlates with the nuclear accumulation and sequence-specific
binding of STAT1 to IFN-γ-responsive promoters. However, neither synthesis
nor secretion of IFN-γ or other IFNs seems to be required for the
IE1-dependent effects on cellular gene expression. Our results demonstrate that
a single hCMV protein can trigger a pro-inflammatory host transcriptional
response via an unexpected STAT1-dependent but IFN-independent mechanism and
identify IE1 as a candidate determinant of hCMV pathogenicity
A functional inference for multivariate current status data with mismeasured covariate
[[abstract]]Covariate measurement error problems have been recently studied for current status failure time data but not yet for multivariate current status data. Motivated by the three-hypers dataset from a health survey study, where the failure times for three-hypers (hyperglycemia, hypertension, hyperlipidemia) are subject to current status censoring and the covariate self-reported body mass index may be subject to measurement error, we propose a functional inference method under the proportional odds model for multivariate current status data with mismeasured covariates. The new proposal utilizes the working independence strategy to handle correlated current status observations from the same subject, as well as the conditional score approach to handle mismeasured covariate without specifying the covariate distribution. The asymptotic theory, together with a stable computation procedure combining the Newton–Raphson and self-consistency algorithms, is established for the proposed estimation method. We evaluate the method through simulation studies and illustrate it with three-hypers data.[[notice]]補正完