1,802 research outputs found
A Simple Questionnaire Can Change Everything: Are Strategy Choices in Coordination Games Stable?
This paper presents results from an experiment designed to study the effect of self reporting risk preferences on strategy choices made in a subsequently played 2× 2 coordination game.The main finding is that the act of answering a questionnaire about one\u27s own risk preferences significantly alters strategic behavior. Within a best response correspondence framework, this result can be explained by a change in either risk preferences or beliefs. We find that self reporting risk preferences induces an increase in subjects\u27 risk aversion while keeping their beliefs unchanged. Our findings raise some questions about the stability of strategy choices in coordination games
How Sensitive is Strategy Selection in Coordination Games?
This paper presents the results of an experiment designed to study the effect produced on strategy choices when a subject reports risk preferences on a risk scale before engaging in a 2x2 coordination game. The main finding is that the act of stating one\u27s own risk preferences significantly alters strategic behavior. In particular, subjects tend to choose the risk dominant strategy more often when they have previously stated their attitudes to risk. Within a best-response correspondence framework, this result can be explained by a change in either risk preferences or beliefs. We find that self-reporting risk preferences does not induce a change in subjects\u27 beliefs. We argue that the behavioral arguments of strategy selection, such as focal points, framing and uncertain preferences can explain our results
A Simple Questionnaire Can Change Everything - Are Strategy Choices in Coordination Games Stable?
This paper presents results from an experiment designed to study the effect of self reporting risk preferences on strategy choices made in a subsequently played 2× 2 coordination game.The main finding is that the act of answering a questionnaire about one's own risk preferences significantly alters strategic behavior. Within a best response correspondence framework, this result can be explained by a change in either risk preferences or beliefs. We find that self reporting risk preferences induces an increase in subjects' risk aversion while keeping their beliefs unchanged. Our findings raise some questions about the stability of strategy choices in coordination games.coordination game, questionnaire, risk preferences, beliefs, best response correspondence
A Strategy for Identifying the Grid Stars for the Space Interferometry Mission (SIM)
We present a strategy to identify several thousand stars that are
astrometrically stable at the micro-arcsecond level for use in the SIM (Space
Interferometry Mission) astrometric grid. The requirements on the grid stars
make this a rather challenging task. Taking a variety of considerations into
account we argue for K giants as the best type of stars for the grid, mainly
because they can be located at much larger distances than any other type of
star due to their intrinsic brightness. We show that it is possible to identify
suitable candidate grid K giants from existing astrometric catalogs. However,
double stars have to be eliminated from these candidate grid samples, since
they generally produce much larger astrometric jitter than tolerable for the
grid. The most efficient way to achieve this is probably by means of a radial
velocity survey. To demonstrate the feasibility of this approach, we repeatedly
measured the radial velocities for a pre-selected sample of 86 nearby Hipparcos
K giants with precisions of 5-8 m/s. The distribution of the intrinsic radial
velocity variations for the bona-fide single K giants shows a maximum around 20
m/s, which is small enough not to severely affect the identification of stellar
companions around other K giants. We use the results of our observations as
input parameters for Monte-Carlo simulations on the possible design of a radial
velocity survey of all grid stars. Our favored scenario would result in a grid
which consists to 68% of true single stars and to 32% of double or multiple
stars with periods mostly larger than 200 years, but only 3.6% of all grid
stars would display astrometric jitter larger than 1 microarcsecond. This
contamination level is probably tolerable.Comment: LaTeX, 21 pages, 8 figures, accepted by PASP (February 2001 issue).
Also available at http://beehive.ucsd.edu/ftp/pub/grid/kgiants.htm
Non-Oberbeck-Boussinesq effects in turbulent thermal convection in ethane close to the critical point
As shown in earlier work (Ahlers et al., J. Fluid Mech. 569, p.409 (2006)),
non-Oberbeck Boussinesq (NOB) corrections to the center temperature in
turbulent Rayleigh-Benard convection in water and also in glycerol are governed
by the temperature dependences of the kinematic viscosity and the thermal
diffusion coefficient. If the working fluid is ethane close to the critical
point the origin of non-Oberbeck-Boussinesq corrections is very different, as
will be shown in the present paper. Namely, the main origin of NOB corrections
then lies in the strong temperature dependence of the isobaric thermal
expansion coefficient \beta(T). More precisely, it is the nonlinear
T-dependence of the density \rho(T) in the buoyancy force which causes another
type of NOB effect. We demonstrate that through a combination of experimental,
numerical, and theoretical work, the latter in the framework of the extended
Prandtl-Blasius boundary layer theory developed in Ahlers et al., J. Fluid
Mech. 569, p.409 (2006). The latter comes to its limits, if the temperature
dependence of the thermal expension coefficient \beta(T) is significant.Comment: 18 pages, 15 figures, 3 table
The potential role of T-cells and their interaction with antigen-presenting cells in mediating immunosuppression following trauma-hemorrhage
Objective: Trauma-hemorrhage results in depressed immune responses of antigen-presenting cells (APCs) and T-cells. Recent studies suggest a key role of depressed T-cell derived interferon (IFN)-g in this complex immune cell interaction. The aim of this study was to elucidate further the underlying mechanisms responsible for dysfunctional T-cells and their interaction with APCs following trauma-hemorrhage.
Design: Adult C3H/HeN male mice were subjected to trauma-hemorrhage (3-cm midline laparotomy) followed by hemorrhage (blood pressure of 35�5mmHg for 90 min and resuscitation) or sham operation. At 24 h thereafter, spleens were harvested and T-cells (by Microbeads) and APCs (via adherence) were Isolated. Co-cultures of T-cells and APCs were established for 48 h and stimulated with concanavalin A and lipopolysaccharide. T-Cell specific cytokines known to affect APC function (i.e. interleukin(IL)-2, IL-4 and granulocyte-macrophage colony-stimulating factor (GM-CSF)) were measured in culture supernatants by Multiplex assay. The expression of MHC class II as well as co-stimulatory surface molecules on T-cells and APCs was determined by flow cytometry.
Results: The release of IL-4 and GM-CSF by T-cells was suppressed following trauma-hemorrhage, irrespective of whether sham or trauma-hemorrhage APCs were present. Antigen-presenting cells from animals subjected to trauma-hemorrhage did not affect T-cell derived cytokine release by sham T-cells. In contrast, T-cells from traumahemorrhage animals depressed MHC class II expression of CD11c(þ) cells, irrespective of whether APCs underwent sham or trauma-hemorrhage procedure. Surprisingly, co-stimulatory molecules on APCs (CD80, CD86) were not affected by trauma-hemorrhage.
Conclusions: These results suggest that beside IFN-g other T-cell derived cytokines contribute to immunosuppression following trauma-hemorrhage causing diminished MHC II expression on APCs. Thus, T-cells appear to play an important role in this interaction at the time-point examined. Therapeutic approaches should aim at maintenance of T-cell function and their interaction with APCs to prevent extended immunosuppression following trauma-hemorrhage
Boundary layer structure in turbulent thermal convection and its consequences for the required numerical resolution
Results on the Prandtl-Blasius type kinetic and thermal boundary layer
thicknesses in turbulent Rayleigh-B\'enard convection in a broad range of
Prandtl numbers are presented. By solving the laminar Prandtl-Blasius boundary
layer equations, we calculate the ratio of the thermal and kinetic boundary
layer thicknesses, which depends on the Prandtl number Pr only. It is
approximated as for and as for
, with . Comparison of the Prandtl--Blasius velocity
boundary layer thickness with that evaluated in the direct numerical
simulations by Stevens, Verzicco, and Lohse (J. Fluid Mech. 643, 495 (2010))
gives very good agreement. Based on the Prandtl--Blasius type considerations,
we derive a lower-bound estimate for the minimum number of the computational
mesh nodes, required to conduct accurate numerical simulations of moderately
high (boundary layer dominated) turbulent Rayleigh-B\'enard convection, in the
thermal and kinetic boundary layers close to bottom and top plates. It is shown
that the number of required nodes within each boundary layer depends on Nu and
Pr and grows with the Rayleigh number Ra not slower than \sim\Ra^{0.15}. This
estimate agrees excellently with empirical results, which were based on the
convergence of the Nusselt number in numerical simulations
Universality in fully developed turbulence
We extend the numerical simulations of She et al. [Phys.\ Rev.\ Lett.\ 70,
3251 (1993)] of highly turbulent flow with Taylor-Reynolds number
up to , employing a reduced wave
vector set method (introduced earlier) to approximately solve the Navier-Stokes
equation. First, also for these extremely high Reynolds numbers ,
the energy spectra as well as the higher moments -- when scaled by the spectral
intensity at the wave number of peak dissipation -- can be described by
{\it one universal} function of for all . Second, the ISR
scaling exponents of this universal function are in agreement with
the 1941 Kolmogorov theory (the better, the large is), as is the
dependence of . Only around viscous damping leads to
slight energy pileup in the spectra, as in the experimental data (bottleneck
phenomenon).Comment: 14 pages, Latex, 5 figures (on request), 3 tables, submitted to Phys.
Rev.
Eccentric lamellar keratolimbal grafts harvested with a manually guided microkeratome
Background: To perform lamellar keratolimbal allograft transplantation in a one- step procedure with a single graft, we investigated the feasibility of harvesting eccentric lamellar keratolimbal grafts from conventionally processed corneoscleral buttons using a manually guided microkeratome in conjunction with an artificial anterior chamber system. Methods: We used the Moria LSK- One microkeratome and the automated lamellar therapeutic keratoplasty ( ALTK) system ( Antony, France). Ten human donor eyes were used to obtain single- piece lamellar keratolimbal grafts. Specimens were processed for light and electron microscopy. Results: Eccentric keratolimbal grafts could be obtained from all human donor buttons. Grafts include a crescent- shaped limbal and a large corneal portion. No visible damage to the limbal region was discernible. Conclusion: Our data show that the LSK- One microkeratome in conjunction with the ALTK system allows harvesting eccentric keratolimbal grafts from donor corneoscleral buttons. Copyright (c) 2007 S. Karger AG, Basel
Holocellulase activity from Schizophyllum commune grown on bamboo: a comparison with different substrates.
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