56,895 research outputs found
The low-temperature geochemical cycle of iron: From continental fluxes to marine sediment deposition
Suspended sediments from 34 major rivers (geographically widespread)and 36 glacial meltwater streams have been examined for their variations in different operationally-defined iron fractions; FeHR (iron oxides soluble in dithionite), FePR (iron soluble in boiling HCl but not in dithionite) and FeU (total iron less that soluble in boiling HCl). River particulates show a close association between FeHR and total iron (FeT), reflecting the effects of chemical weathering which derive oxide iron
from, and retain it in close association with, total iron. Consistent with this, continentalscale
average FeHR/FeT ratios vary with runoff ratios (average river runoff per unit
area/average precipitation per unit area). By contrast, the diminished effects of
chemical weathering produce no recognizable association of FeHR with FeT in glacial
particulates, and instead both FePR and FeU are closely correlated with FeT, reflecting
essentially pristine mineralogy. A comparison of the globally-averaged compositions of
riverine particulates and marine sediments reveals that the latter are depleted in FeHR,
FePR and FeT but enriched in FeU. The river and glacial particulate data are combined
with estimates of authigenic, hydrothermal, atmospheric and coastal erosive iron
fluxes from the literature to produce a global budget for FeHR, FePR, FeU and FeT.
This budget suggests that the differences between riverine particulates and marine
sediments can be explained by; (i) preferentially removing FeHR from the riverine
particulate flux by deposition into inner shore reservoirs such as floodplains, salt
marshes and estuaries; and (ii) mixing the resulting riverine particulates with FeHRdepleted
glacial particulates. Preliminary measurements of inner shore sediments are
consistent with (i) above. Phanerozoic and modern normal marine sediments have
similar iron speciation characteristics, which implies the existence of a long-term
steady state for the iron cycle. This steady state could be maintained by a glacioeustatic
feedback, where FeHR-enriched riverine particulates are either more effectively trapped
when sealevel is high (small ice masses, diminished glacial erosion), or are mixed with
greater masses of FeHR-depleted glacial particulates when sealevel is low (large ice
masses, enhanced glacial erosion). Further important controls on the steady state for FeHR operate through the formation of euxinic sediments and ironstones, which also
provide sealevel-dependent sinks for FeHR-enriched sediment
An Extension to the Model of Inequity Aversion by Fehr and Schmidt
The aim of this paper is to improve on the model by Fehr and Schmidt (1999) by developing a non-linear model (that leads to interior rather than corner solutions) and by taking into account that different levels of income imply different reactions of fair-minded people. We suggest to modify the inequity-aversion utility function proposed by Fehr and Schmidt by taking into account not only the difference between players' payoffs, but also their absolute value. This allows for a non-linear utility function where different stakes lead to different unique optimal interior solutions.
On the metric dimension of corona product graphs
Given a set of vertices of a connected graph , the
metric representation of a vertex of with respect to is the vector
, where ,
denotes the distance between and . is a resolving set for if
for every pair of vertices of , . The metric
dimension of , , is the minimum cardinality of any resolving set for
. Let and be two graphs of order and , respectively. The
corona product is defined as the graph obtained from and by
taking one copy of and copies of and joining by an edge each
vertex from the -copy of with the -vertex of . For any
integer , we define the graph recursively from
as . We give several results on the metric
dimension of . For instance, we show that given two connected
graphs and of order and , respectively, if the
diameter of is at most two, then .
Moreover, if and the diameter of is greater than five or is
a cycle graph, then $dim(G\odot^k H)=n_1(n_2+1)^{k-1}dim(K_1\odot H).
Inequality Aversion, Efficiency, and Maximin Preferences in Simple Distribution Experiments
We present simple one-shot distribution experiments comparing the relative im-portanceof efficiency, maximin preferences and inequality aversion, as well asthe relative performance of the fairness theories by Bolton and Ockenfels (2000)and Fehr and Schmidt (1999). While the Fehr and Schmidt model performsbetter in a direct comparison, this appears to be due to being in line with max-iminpreferences. More importantly, we find that the influence of both efficiencyand maximin preferences is stronger than that of inequality aversion. We discusspotential implications our results might have for the interpretation of otherexperiments.economics of technology ;
The Garden Hose Complexity for the Equality Function
The garden hose complexity is a new communication complexity introduced by H.
Buhrman, S. Fehr, C. Schaffner and F. Speelman [BFSS13] to analyze
position-based cryptography protocols in the quantum setting. We focus on the
garden hose complexity of the equality function, and improve on the bounds of
O. Margalit and A. Matsliah[MM12] with the help of a new approach and of our
handmade simulated annealing based solver. We have also found beautiful
symmetries of the solutions that have lead us to develop the notion of garden
hose permutation groups. Then, exploiting this new concept, we get even
further, although several interesting open problems remain.Comment: 16 page
On the Explanatory Value of Inequity Aversion Theory
In a number of papers on their theory of Inequity Aversion, E. Fehr and K. Schmidt have claimed that the theory explains the behavior in many experiments. By virtue of having an infinite number of parameters the theory can predict a wide range of outcomes, from the competitive to the cooperative. Its prediction depends on values of these parameters. Fehr & Schmidt provide no explicit methodological plan for their project and as a result they repeatedly make logical and methodological errors. We look at the methodology of their explanations and find that no connection has been established between the experimental data and the behavior predicted by the theory. We conclude that the theory of inequity aversion has no explanatory value beyond its trivial capacity to predict a broad range of outcomes as a function of its parameters
Culture Outsmarts Nature in the Evolution of Cooperation
A one dimensional cellular automata model describes the evolutionary dynamics of cooperation when grouping by cooperators provides protection against predation. It is used to compare the dynamics of evolution of cooperation in three settings. G: only vertical transmission of information is allowed, as an analogy of genetic evolution with heredity; H: only horizontal information transfer is simulated, through diffusion of the majority\'s opinion, as an analogy of opinion dynamics or social learning; and C: analogy of cultural evolution, where information is transmitted both horizontally (H) and vertically (V) so that learned behavior can be transmitted to offspring. The results show that the prevalence of cooperative behavior depends on the costs and benefits of cooperation so that: a- cooperation becomes the dominant behavior, even in the presence of free-riders (i.e., non-cooperative obtaining benefits from the cooperation of others), under all scenarios, if the benefits of cooperation compensate for its cost; b- G is more susceptible to selection pressure than H achieving a closer adaptation to the fitness landscape; c- evolution of cooperative behavior in H is less sensitive to the cost of cooperation than in G; d- C achieves higher levels of cooperation than the other alternatives at low costs, whereas H does it at high costs. The results suggest that a synergy between H and V is elicited that makes the evolution of cooperation much more likely under cultural evolution than under the hereditary kind where only V is present.Social Simulation, Interactions, Group Size, Selfish Heard, Cultural Evolution, Biological Evolution
- …