4,568 research outputs found
Dynamic oligopolies and intertemporal demand interaction
Dynamic oligopolies are examined with continuous time scales and under the assumption that the demand at each time period is affected by earlier demands and consumptions. After the mathematical model is introduced the local asymptotical stability of the equilibrium is examined, and then we will discuss how information delays alter the stability conditions. We will also investigate the occurrence of a Hopf bifurcation gving the possibility of the birth of limit cycles. Numerical examples will be shown toillustrate the theoretical results
A multiobjective model of oligopolies under uncertainty
It is assumed that in an n-firm single-product oligopoly without product differentiation the firms face an uncertain price function, which is considered random by the firms. At each time period each firm simultaneously maximizes its expected profit and minimizes the variance of the profit since it wants to receive as high as possible profit with the least possible uncertainty. It is assumed that the best response of each firm is obtained by the weighting method. We show the existence of a unique equilibrium, and investigate the local stability of the equilibrium
Microwave intermodulation distortion of MgB2 thin films
The two tone intermodulation arising in MgB2 thin films deposited in-situ by
planar magnetron sputtering on sapphire substrates is studied. Samples are
characterised using an open-ended dielectric puck resonator operating at 8.8
GHz. The experimental results show that the third order products increase with
the two-tone input power with a slope ranging between 1.5 and 2.3. The
behaviour can be understood introducing a mechanism of vortex penetration in
grain boundaries as the most plausible source of non linearities in these
films. This assumption is confirmed by the analysis of the field dependence of
the surface resistance, that show a linear behaviour at all temperatures under
test.Comment: 13 pages, 3 figures; to be published in Appl. Phys. Let
Quantum phase slips in superconducting Nb nanowire networks deposited on self-assembled Si templates
Robust porous silicon substrates were employed for generating interconnected
networks of superconducting ultrathin Nb nanowires. Scanning electron
microscopy analysis was performed to investigate the morphology of the samples,
which constitute of polycrystalline single wires with grain size of about 10
nm. The samples exhibit nonzero resistance over a broad temperature range below
the critical temperature, fingerprint of phase slippage processes. The
transport data are satisfactory reproduced by models describing both thermal
and quantum fluctuations of the superconducting order parameter in thin
homogeneous superconducting wires.Comment: accepted for publication on Applied Physics Letter
Modeling house price dynamics with heterogeneous speculators
This paper investigates the impact of speculative behavior on house price dynamics. Speculative demand for housing is modeled using a heterogeneous agent approach, whereas ‘real’ demand and housing supply are represented in a standard way. Together, real and speculative forces determine excess demand in each period and house price adjustments. Three alternative models are proposed, capturing in different ways the interplay between fundamental trading rules and extrapolative trading rules, resulting in a 2D, a 3D, and a 4D nonlinear discretetime dynamical system, respectively. While the destabilizing effect of speculative behavior on the model’s steady state is proven in general, the three specific cases illustrate a variety of situations that can bring about endogenous dynamics, with lasting and significant price swings around the ‘fundamental ’ price, as we have seen in many real markets
Computational analysis of Human Immunodeficiency Virus (HIV) Type-1 reverse transcriptase crystallographic models based on significant conserved residues found in Highly Active Antiretroviral Therapy (HAART)-treated patients.
Reverse transcription of the viral single-stranded (+) RNA genome into double-stranded DNA is an essential step in the human immunodeficiency virus' (HIV) life-cycle. Although several viral proteins are involved in the regulation and/or efficiency of reverse transcription, the process of retroviral DNA synthesis is entirely dependent on the enzymatic activities of the retroviral reverse transcriptase enzyme (RT). Due to its crucial role in the HIV life-cycle, RT is a primary target for anti-HIV drug development. Nonetheless, drug resistance is the major problem affecting the clinical efficacy of antiretroviral agents. Incomplete pharmacological pressure represents the logical cause and not the consequence of different mutation pathways in RT associated with approved inhibitors resistance.
In this review we have analyzed RT Protein Data Bank (PDB) models using our innovative computational approach “GRID Based Pharmacophore Model” (GBPM). This method was applied to clinically relevant RT conserved residues found in a large cohort of HAART treated patients. The PDB entries have been selected among the unbound and the complexed models with DNA and/or inhibitors. Such an approach has revealed itself useful to highlight the mutation effects in the drug-RT recognition as well as in the heterodimer stabilization of the enzyme. Most of the clinical and biochemical evidences already reported in the literature have been rationalized at molecular level via the GBPM computational approach. A definite future application of this method will be the identification of conserved regions of critical macromolecules, such as the HIV-1 RT, to be targeted for the development of innovative therapeutic agents
- …