2,415 research outputs found
Genuine Non-Self-Averaging and Ultra-Slow Convergence in Gelation
In irreversible aggregation processes droplets or polymers of microscopic
size successively coalesce until a large cluster of macroscopic scale forms.
This gelation transition is widely believed to be self-averaging, meaning that
the order parameter (the relative size of the largest connected cluster)
attains well-defined values upon ensemble averaging with no sample-to-sample
fluctuations in the thermodynamic limit. Here, we report on anomalous gelation
transition types. Depending on the growth rate of the largest clusters, the
gelation transition can show very diverse patterns as a function of the control
parameter, which includes multiple stochastic discontinuous transitions,
genuine non-self-averaging and ultra-slow convergence of the transition point.
Our framework may be helpful in understanding and controlling gelation.Comment: 8 pages, 10 figure
Spin Wave Response in the Dilute Quasi-one Dimensional Ising-like Antiferromagnet CsCo_{0.83}Mg_{0.17}Br_3
Inelastic neutron scattering profiles of spin waves in the dilute
quasi-one-dimensional Ising-like antiferromagnet CsCo_{0.83}Mg_{0.17}Br_3 have
been investigated. Calculations of S^{xx}(Q,omega), based on an effective spin
Hamiltonian, accurately describe the experimental spin wave spectrum of the 2J
mode. The Q dependence of the energy of this spin wave mode follows the
analytical prediction
omega_{xx}(Q)=(2J)(1-5epsilon^{2}cos^{2}Qa+2epsilon^{2})^{1/2}, calculated by
Ishimura and Shiba using perturbation theory.Comment: 13 pages, 4 figure
Impact of embedding on predictability of failure-recovery dynamics in networks
Failure, damage spread and recovery crucially underlie many spatially
embedded networked systems ranging from transportation structures to the human
body. Here we study the interplay between spontaneous damage, induced failure
and recovery in both embedded and non-embedded networks. In our model the
network's components follow three realistic processes that capture these
features: (i) spontaneous failure of a component independent of the
neighborhood (internal failure), (ii) failure induced by failed neighboring
nodes (external failure) and (iii) spontaneous recovery of a component.We
identify a metastable domain in the global network phase diagram spanned by the
model's control parameters where dramatic hysteresis effects and random
switching between two coexisting states are observed. The loss of
predictability due to these effects depend on the characteristic link length of
the embedded system. For the Euclidean lattice in particular, hysteresis and
switching only occur in an extremely narrow region of the parameter space
compared to random networks. We develop a unifying theory which links the
dynamics of our model to contact processes. Our unifying framework may help to
better understand predictability and controllability in spatially embedded and
random networks where spontaneous recovery of components can mitigate
spontaneous failure and damage spread in the global network.Comment: 22 pages, 20 figure
Gender gap in the ERASMUS mobility program
Studying abroad has become very popular among students. The ERASMUS mobility
program is one of the largest international student exchange programs in the
world, which has supported already more than three million participants since
1987. We analyzed the mobility pattern within this program in 2011-12 and found
a gender gap across countries and subject areas. Namely, for almost all
participating countries, female students are over-represented in the ERASMUS
program when compared to the entire population of tertiary students. The same
tendency is observed across different subject areas. We also found a gender
asymmetry in the geographical distribution of hosting institutions, with a bias
of male students in Scandinavian countries. However, a detailed analysis
reveals that this latter asymmetry is rather driven by subject and consistent
with the distribution of gender ratios among subject areas
The use of indicators for unobservable product qualities: inferences based on consumer sorting
Using the dietary supplement black cohosh to demonstrate our method, we employ data on a product characteristic unobservable to consumers to decompose the contribution to consumers’ valuations of observable characteristics into surrogate indicator and direct components. Because consumers are not all “expert appraisers” of the unobservable characteristic, the measured relationship of indicators to the unobservable quality is generally not the one consumers perceive. Consequently, biases that depend upon the nature of consumers’ ineptitude are introduced into the component estimation. The researcher’s inference problem is solved by recognizing that consumers with greater appraisal expertise sort disproportionately to higher quality products. This enables feasible measurement of inept consumers’ relative valuations and conjectures through separate hedonic estimation on high- and low-quality product subsamples. We find that, relative to experts, inept consumers likely underestimate the value of most observable characteristics in indicating black cohosh product authenticity; however they overweight online product ratings.hedonic analysis; surrogate indicators; asymmetric information; pricing strategy; product strategy
Out With the Old, In With the New: Are Western Commodity Producers Ready for Buyouts?
Agricultural and Food Policy,
- …