548 research outputs found
Monopoly Market with Externality: an Analysis with Statistical Physics and ACE
In this paper, we explore the effects of localised externalities introduced through interaction structures upon the properties of the simplest market model: the discrete choice model with a single homogeneous product and a single seller (the monopoly case). The resulting market is viewed as a complex interactive system with a communication network. Our main goal is to understand how generic properties of complex adaptive systems can enlighten our understanding of the market mechanisms when individual decisions are inter-related. To do so we make use of an ACE (Agent based Computational Economics) approach, and we discuss analogies between simulated market mechanisms and classical collective phenomena studied in Statistical Physics. More precisely, we consider discrete choice models where the agents are subject to local positive externality. We compare two extreme special cases, the McFadden (McF) and the Thurstone (TP) models. In the McF model the individuals' willingness to pay are heterogeneous, but remain fixed. In the TP model, all the agents have the same homogeneous part of willingness to pay plus an additive random (logistic) idiosyncratic characteristic. We show that these models are formally equivalent to models studied in the Physics literature, the McF case corresponding to a `Random Field Ising model' (RFIM) at zero temperature, and the TP case to an Ising model at finite temperature in a uniform (non random) external field. From the physicist's point of view, the McF and the TP models are thus quite different: they belong to the classes of, respectively,`quenched' and `annealed' disorder, which are known to lead to very different aggregate behaviour. This paper explores some consequences for market behaviour. Considering the optimisation of profit by the monopolist, we exhibit a new `first order phase transition': if the social influence is strong enough, there is a regime where, if the mean willingness to pay increases, or if the production costs decreases, the optimal solution for the monopolist jumps from a solution with a high price and a small number of buyers, to a solution with a low price and a large number of buyers.Agent-Based Computational Economics, discret choices, consumers externality, complex adaptive system, phase transition, avalanches, interactions, hysteresis.
HIF and c-Myc: Sibling Rivals for Control of Cancer Cell Metabolism and Proliferation
O2 deprivation (hypoxia) and cellular proliferation engage opposite cellular pathways, yet often coexist during tumor growth. The ability of cells to grow during hypoxia results in part from crosstalk between hypoxia-inducible factors (HIFs) and the proto-oncogene c-Myc. Acting alone, HIF and c-Myc partially regulate complex adaptations undertaken by tumor cells growing in low O2. However, acting in concert these transcription factors reprogram metabolism, protein synthesis, and cell cycle progression, to “fine tune” adaptive responses to hypoxic environments
Cohomology of the Lie Superalgebra of Contact Vector Fields on and Deformations of the Superspace of Symbols
Following Feigin and Fuchs, we compute the first cohomology of the Lie
superalgebra of contact vector fields on the (1,1)-dimensional
real superspace with coefficients in the superspace of linear differential
operators acting on the superspaces of weighted densities. We also compute the
same, but -relative, cohomology. We explicitly give
1-cocycles spanning these cohomology. We classify generic formal
-trivial deformations of the -module
structure on the superspaces of symbols of differential operators. We prove
that any generic formal -trivial deformation of this
-module is equivalent to a polynomial one of degree .
This work is the simplest superization of a result by Bouarroudj [On
(2)-relative cohomology of the Lie algebra of vector fields and
differential operators, J. Nonlinear Math. Phys., no.1, (2007), 112--127].
Further superizations correspond to -relative cohomology
of the Lie superalgebras of contact vector fields on -dimensional
superspace
Reduced skeletal muscle protein balance in paediatric Crohn’s disease
Background and AimsAn inability to respond to nutrition could be implicated in low muscle mass in Crohn’s disease. We aim to determine skeletal muscle metabolic response to feeding in Crohn’s disease and healthy volunteers.MethodsTwenty asymptomatic Crohn’s disease participants (15.6 ± 0.5 yrs; BMI 20.6 ± 0.9 kg/m2); 9 with active disease (faecal calprotectin, 808 ± 225ug/g and C-reactive protein, 2.2 ± 1.2 mg/dl), 11 in deep remission (faecal calprotectin, 61 ± 12ug/g and C-reactive protein, 0.3 ± 0.2 mg/dl) and 9 matched healthy volunteers (16.0±0.6 yrs; BMI 20.7±0.6 kg/m2) were recruited. Participants had a dual energy X-ray absorptiometry scan, handgrip dynamometer test, wore a pedometer and completed a food diary. Arterialised hand and venous forearm blood samples were collected concurrently and brachial artery blood flow measured at baseline and every 20mins for 2hrs after the ingestion of a standardised liquid meal. Net balance of branched chain amino acids and glucose were derived.ResultsControls had a positive mean BCAA balance. CD participants had an initial anabolic response to the meal, with increasing BCAA balance between t=0 & t=20, but returned to negative by t=60. This was associated with reduced FFM z-scores in CD but not with insulin resistance or disease activity. Exploratory analyses suggest that negative postprandial BCAA response seen in CD is predominant in males (p=0.049), with associated lower appendicular muscle mass (p=0.034), higher muscle fatigue (p=0.014) and reduced protein intake (p=0.026).ConclusionsThe inability to sustain a positive protein balance postprandially could provide an explanation for the reduced muscle mass seen in CD. Further mechanistic studies will be needed to confirm these findings
On sl(2)-equivariant quantizations
By computing certain cohomology of Vect(M) of smooth vector fields we prove
that on 1-dimensional manifolds M there is no quantization map intertwining the
action of non-projective embeddings of the Lie algebra sl(2) into the Lie
algebra Vect(M). Contrariwise, for projective embeddings sl(2)-equivariant
quantization exists.Comment: 09 pages, LaTeX2e, no figures; to appear in Journal of Nonlinear
Mathematical Physic
The Influence of E - Stim on Posture and Respiratory Function to Improve Aerobic Capacity: A Pilot
poste
Supplementary material for the article: Čolić, S. D.; Fotirić Akšić, M. M.; Lazarević, K. B.; Zec, G. N.; Gašić, U. M.; Dabić Zagorac, D. Č.; Natić, M. M. Fatty Acid and Phenolic Profiles of Almond Grown in Serbia. Food Chemistry 2017, 234, 455–463. https://doi.org/10.1016/j.foodchem.2017.05.006
Supplementary material for: [https://doi.org/10.1016/j.foodchem.2017.05.006 ]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2473]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3215
Satisfaction with dental care among patients who receive invasive or non-invasive treatment for non-cavitated early dental caries: findings from one region of the National Dental PBRN
Atomic Dark Matter
We propose that dark matter is dominantly comprised of atomic bound states.
We build a simple model and map the parameter space that results in the early
universe formation of hydrogen-like dark atoms. We find that atomic dark matter
has interesting implications for cosmology as well as direct detection:
Protohalo formation can be suppressed below for weak scale dark matter due to Ion-Radiation interactions in the
dark sector. Moreover, weak-scale dark atoms can accommodate hyperfine
splittings of order 100 \kev, consistent with the inelastic dark matter
interpretation of the DAMA data while naturally evading direct detection
bounds.Comment: 17 pages, 3 figure
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