5,824 research outputs found
An Experimental Analysis ofGroup Size and Risk Sharing
We study the relationship between group size and the extent of risk sharing in an insurance game played over a number of periods with random idiosyncratic and aggregate shocks to income in each period. Risk sharing is attained via agents that receive a high endowment in one period making unilateral transfers to agents that receive a low endowment in that period. The complete risk sharing allocation is for all agents to place their endowments in a common pool, which is then shared equally among members of the group in every period. Theoretically, the larger the group size, the smaller the per capita dispersion in consumption and greater is the potential value of insurance. Field evidence however suggests that smaller groups do better than larger groups as far as risk sharing is concerned. Results from our experiments show that the extent of mutual insurance is significantly higher in smaller groups, though contributions to the pool are never close to what complete risk sharing requires.Reciprocity, Risk Sharing, Group Size, Experiments
Do Attitudes Towards Corruption Differ Across Cultures? Experimental Evidence from Australia, India, Indonesia andSingapore
This paper examines cultural differences in attitudes towards corruption by analysing individual-decision making in a corrupt experimental environment. Attitudes towards corruption play a critical role in the persistence of corruption. Our experiments differentiate between the incentives to engage in corrupt behaviour and the incentives to punish corrupt behaviour and allow us to explore whether, in environments characterized by lower levels of corruption, there is both a lower propensity to engage in corrupt behaviour and a higher propensity to punish corrupt behaviour. Based on experiments run in Australia (Melbourne), India (Delhi), Indonesia (Jakarta) and Singapore, we find that there is more variation in the propensities to punish corrupt behaviour than in the propensities to engage in corrupt behaviour across cultures. The results reveal that the subjects in India exhibit a higher tolerance towards corruption than the subjects in Australia while the subjects in Indonesia behave similarly to those in Australia. The subjects in Singapore have a higher propensity to engage in corruption than the subjects in Australia. We also vary our experimental design to examine the impact of a more effective punishment system and the effect of the perceived cost of bribery.Corruption, Experiments, Punishment, Cultural Analysis
Deconfinement and the Hagedorn Transition in String Theory
Superseded and extended in hep-th/0105110 and hep-th/0208112.Comment: Superseded and extended in hep-th/0105110 and hep-th/020811
Heat conduction and phonon localization in disordered harmonic crystals
We investigate the steady state heat current in two and three dimensional
isotopically disordered harmonic lattices. Using localization theory as well as
kinetic theory we estimate the system size dependence of the current. These
estimates are compared with numerical results obtained using an exact formula
for the current given in terms of a phonon transmission function, as well as by
direct nonequilibrium simulations. We find that heat conduction by
high-frequency modes is suppressed by localization while low-frequency modes
are strongly affected by boundary conditions. Our {\color{black}heuristic}
arguments show that Fourier's law is valid in a three dimensional disordered
solid except for special boundary conditions. We also study the pinned case
relevant to localization in quantum systems and often used as a model system to
study the validity of Fourier's law. Here we provide the first numerical
verification of Fourier's law in three dimensions. In the two dimensional
pinned case we find that localization of phonon modes leads to a heat
insulator.Comment: 5 pages, 3 figure
Dissipative hydrodynamics in 2+1 dimension
In 2+1 dimension, we have simulated the hydrodynamic evolution of QGP fluid
with dissipation due to shear viscosity. Comparison of evolution of ideal and
viscous fluid, both initialised under the same conditions e.g. same
equilibration time, energy density and velocity profile, reveal that the
dissipative fluid evolves slowly, cooling at a slower rate. Cooling get still
slower for higher viscosity. The fluid velocities on the otherhand evolve
faster in a dissipative fluid than in an ideal fluid. The transverse expansion
is also enhanced in dissipative evolution. For the same decoupling temperature,
freeze-out surface for a dissipative fluid is more extended than an ideal
fluid. Dissipation produces entropy as a result of which particle production is
increased. Particle production is increased due to (i) extension of the
freeze-out surface and (ii) change of the equilibrium distribution function to
a non-equilibrium one, the last effect being prominent at large transverse
momentum. Compared to ideal fluid, transverse momentum distribution of pion
production is considerably enhanced. Enhancement is more at high than at
low . Pion production also increases with viscosity, larger the viscosity,
more is the pion production. Dissipation also modifies the elliptic flow.
Elliptic flow is reduced in viscous dynamics. Also, contrary to ideal dynamics
where elliptic flow continues to increase with transverse momentum, in viscous
dynamics, elliptic flow tends to saturate at large transverse momentum. The
analysis suggest that initial conditions of the hot, dense matter produced in
Au+Au collisions at RHIC, as extracted from ideal fluid analysis can be changed
significantly if the QGP fluid is viscous.Comment: 11 pages, 10 figures (revised). In the revised version, calculations
are redone with ADS/CFT and perurbative estimate of viscosity. Comments on
the unphysical effects like early reheating of the fluid, in 1st order
dissipative theories are added. The particle spectra calculations are redone
with modified programm
Dissipative hydrodynamics for viscous relativistic fluids
Explicit equations are given for describing the space-time evolution of
non-ideal (viscous) relativistic fluids undergoing boost-invariant longitudinal
and arbitrary transverse expansion. The equations are derived from the
second-order Israel-Stewart approach which ensures causal evolution. Both
azimuthally symmetric (1+1)-dimensional and non-symmetric (2+1)-dimensional
transverse expansion are discussed. The latter provides the formal basis for
the hydrodynamic computation of elliptic flow in relativistic heavy-ion
collisions including dissipative effects.Comment: 12 pages, no figures. Submitted to Physical Review
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Barriers to reporting non-motor symptoms to health-care providers in people with Parkinson's
Background: Non-motor symptoms (NMS) are common in Parkinson's disease (PD) and cause significant distress. A high rate of non-declaration of NMS by patients to healthcare providers (HCP) means that many NMS remain untreated. Current understanding of the factors preventing disclosure of NMS to HCPs is limited. The present study aimed to i) further assess the prevalence of NMS and associated distress, ii) establish current rates of NMS reporting across a range of sources, and iii) explore overall and any symptom specific barriers to help-seeking for NMS.
Methods: 358 PD patients completed a cross-sectional survey of NMS severity, reporting and barriers to help-seeking. A series of Generalised Estimating Equations were used to determine whether barriers were symptom specific.
Results: A mean of 10.5 NMS were reported by each patient. Rates of non-reporting of NMS ranged from 15 to 72% of those experiencing distressing symptoms. The most commonly reported barriers to help-seeking were acceptance of symptoms; lack of awareness that a symptom was associated with PD, and belief that no effective treatments were available. Symptom specific barriers were found for sexual dysfunction (embarrassment), unexplained pain and urinary problems (belief about lack of treatment availability).
Conclusion: A diverse range of barriers prevent PD patients reporting NMS to HCPs and these barriers differ between NMS. The study provides the foundations for developing interventions to increase reporting by targeting individual NMS. Increasing rates of help-seeking for NMS by patients to their Parkinson's healthcare providers will increase appropriate clinical care which may improve quality of life and well-being
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Oxidative stress specifically downregulates survivin to promote breast tumour formation.
BackgroundBreast cancer, a heterogeneous disease has been broadly classified into oestrogen receptor positive (ER+) or oestrogen receptor negative (ER-) tumour types. Each of these tumours is dependent on specific signalling pathways for their progression. While high levels of survivin, an anti-apoptotic protein, increases aggressive behaviour in ER- breast tumours, oxidative stress (OS) promotes the progression of ER+ breast tumours. Mechanisms and molecular targets by which OS promotes tumourigenesis remain poorly understood.ResultsDETA-NONOate, a nitric oxide (NO)-donor induces OS in breast cancer cell lines by early re-localisation and downregulation of cellular survivin. Using in vivo models of HMLE(HRAS) xenografts and E2-induced breast tumours in ACI rats, we demonstrate that high OS downregulates survivin during initiation of tumourigenesis. Overexpression of survivin in HMLE(HRAS) cells led to a significant delay in tumour initiation and tumour volume in nude mice. This inverse relationship between survivin and OS was also observed in ER+ human breast tumours. We also demonstrate an upregulation of NADPH oxidase-1 (NOX1) and its activating protein p67, which are novel markers of OS in E2-induced tumours in ACI rats and as well as in ER+ human breast tumours.ConclusionOur data, therefore, suggest that downregulation of survivin could be an important early event by which OS initiates breast tumour formation
Local methylthiolate adsorption geometry on Au(111) from photoemission core-level shifts
The local adsorption structure of methylthiolate in the ordered Au(111)-(â3Ăâ3)R30° phase has been investigated using core-level-shift measurements of the surface and bulk components of the Au 4f7/2 photoelectron binding energy. The amplitude ratio of the core-level-shift components associated with surface Au atoms that are, and are not, bonded to the thiolate is found to be compatible only with the previously proposed Au-adatom-monothiolate moiety in which the thiolate is bonded atop Au adatoms in hollow sites, and not on an unreconstructed surface, or in Au-adatom-dithiolate species
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