1,754 research outputs found
The prisoners dilemma on a stochastic non-growth network evolution model
We investigate the evolution of cooperation on a non - growth network model
with death/birth dynamics. Nodes reproduce under selection for higher payoffs
in a prisoners dilemma game played between network neighbours. The mean field
characteristics of the model are explored and an attempt is made to understand
the size dependent behaviour of the model in terms of fluctuations in the
strategy densities. We also briefly comment on the role of strategy mutation in
regulating the strategy densties.Comment: 8 pages, 8 figure
Energy Calibration of the JLab Bremsstrahlung Tagging System
In this report, we present the energy calibration of the Hall B
bremsstrahlung tagging system at the Thomas Jefferson National Accelerator
Facility. The calibration was performed using a magnetic pair spectrometer. The
tagged photon energy spectrum was measured in coincidence with pairs
as a function of the pair spectrometer magnetic field. Taking advantage of the
internal linearity of the pair spectrometer, the energy of the tagging system
was calibrated at the level of . The absolute energy scale
was determined using the rate measurements close to the end-point of
the photon spectrum. The energy variations across the full tagging range were
found to be MeV.Comment: 15 pages, 12 figure
Joint evolution of multiple social traits: a kin selection analysis
General models of the evolution of cooperation, altruism and other social behaviours have focused almost entirely on single traits, whereas it is clear that social traits commonly interact. We develop a general kin-selection framework for the evolution of social behaviours in multiple dimensions. We show that whenever there are interactions among social traits new behaviours can emerge that are not predicted by one-dimensional analyses. For example, a prohibitively costly cooperative trait can ultimately be favoured owing to initial evolution in other (cheaper) social traits that in turn change the cost-benefit ratio of the original trait. To understand these behaviours, we use a two-dimensional stability criterion that can be viewed as an extension of Hamilton's rule. Our principal example is the social dilemma posed by, first, the construction and, second, the exploitation of a shared public good. We find that, contrary to the separate one-dimensional analyses, evolutionary feedback between the two traits can cause an increase in the equilibrium level of selfish exploitation with increasing relatedness, while both social (production plus exploitation) and asocial (neither) strategies can be locally stable. Our results demonstrate the importance of emergent stability properties of multidimensional social dilemmas, as one-dimensional stability in all component dimensions can conceal multidimensional instability
Pre- and post-selected ensembles and time-symmetry in quantum mechanics
An expression is proposed for the quantum mechanical state of a pre- and
post-selected ensemble, which is an ensemble determined by the final as well as
the initial state of the quantum systems involved. It is shown that the
probabilities calculated from the proposed state agree with previous
expressions, for cases where they both apply. The same probabilities are found
when they are calculated in the forward- or reverse-time directions. This work
was prompted by several problems raised by Shimony recently in relation to the
state, and time symmetry, of pre- and post-selected ensembles.Comment: RevTex4, 17 pages, no fig
Photofission of heavy nuclei at energies up to 4 GeV
Total photofission cross sections for 238U, 235U, 233U, 237Np, 232Th, and
natPb have been measured simultaneously, using tagged photons in the energy
range Egamma=0.17-3.84 GeV. This was the first experiment performed using the
Photon Tagging Facility in Hall B at Jefferson Lab. Our results show that the
photofission cross section for 238U relative to that for 237Np is about 80%,
implying the presence of important processes that compete with fission. We also
observe that the relative photofission cross sections do not depend strongly on
the incident photon energy over this entire energy range. If we assume that for
237Np the photofission probability is equal to unity, we observe a significant
shadowing effect starting below 1.5 GeV.Comment: 4 pages of RevTex, 6 postscript figures, Submitted to Phys. Rev. Let
Depletion forces near curved surfaces
Based on density functional theory the influence of curvature on the
depletion potential of a single big hard sphere immersed in a fluid of small
hard spheres with packing fraction \eta_s either inside or outside of a hard
spherical cavity of radius R_c is calculated. The relevant features of this
potential are analyzed as function of \eta_s and R_c. There is a very slow
convergence towards the flat wall limit R_c \to \infty. Our results allow us to
discuss the strength of depletion forces acting near membranes both in normal
and lateral directions and to make contact with recent experimental results
Problems with Using Evolutionary Theory in Philosophy
Does science move toward truths? Are present scientific theories (approximately) true? Should we invoke truths to explain the success of science? Do our cognitive faculties track truths? Some philosophers say yes, while others say no, to these questions. Interestingly, both groups use the same scientific theory, viz., evolutionary theory, to defend their positions. I argue that it begs the question for the former group to do so because their positive answers imply that evolutionary theory is warranted, whereas it is self-defeating for the latter group to do so because their negative answers imply that evolutionary theory is unwarranted
Exosomes genetic cargo in lung cancer: a truly Pandora s box
[EN] Lung cancer is a highly lethal disease. Targeted therapies have been developed in last years, however survival rates are not improving due to the delay in the diagnosis, making biomarkers one of the most interesting fields of study in cancer. Liquid biopsy has raised as an alternative to tissue biopsy due to improvements in analytical techniques for circulating tumor cells (CTCs), cell free DNA and exosomes. Among all, exosomes have raised as one of the most promising tools to understand the tumor due to their stability in the blood and their similarity to the cells of origin. In the last years, different alterations have been described inside the exosomes derived from non-small cell lung cancer (NSCLC) cells mirroring the processes inside these tumoral cells, such as EGFR mutation, translocations or microRNA (miRNA) deregulation. All these studies have opened the window to a new world of possibilities in the study of tumor biomarkers.Reclusa P; Sirera Pérez, R.; Araujo, A.; Giallombardo, M.; Valentino, A.; Sober, L.; Gil Bazo, I.... (2016). Exosomes genetic cargo in lung cancer: a truly Pandora s box. Translational Lung Cancer Research. 5(5):483-491. doi:10.21037/tlcr.2016.10.06S4834915
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