Pretender punishment induced by chemical signalling in a queenless ant

Animal societies are stages for both conflict and cooperation. Reproduction is often monopolized by one or a few individuals who behave aggressively to prevent subordinates from reproducing (for example, naked mole-rats, wasps and ants). Here we report an unusual mechanism by which the dominant individual maintains reproductive control. In the queenless ant Dinoponera quadriceps, only the alpha female reproduces. If the alpha is challenged by another female she chemically marks the pretender who is then punished by low-ranking females. This cooperation between alpha and low-rankers allows the alpha to inflict punishment indirectly, thereby maintaining her reproductive primacy without having to figh

Quantum Link Models with Many Rishon Flavors and with Many Colors

Quantum link models are a novel formulation of gauge theories in terms of discrete degrees of freedom. These degrees of freedom are described by quantum operators acting in a finite-dimensional Hilbert space. We show that for certain representations of the operator algebra, the usual Yang-Mills action is recovered in the continuum limit. The quantum operators can be expressed as bilinears of fermionic creation and annihilation operators called rishons. Using the rishon representation the quantum link Hamiltonian can be expressed entirely in terms of color-neutral operators. This allows us to study the large N_c limit of this model. In the 't Hooft limit we find an area law for the Wilson loop and a mass gap. Furthermore, the strong coupling expansion is a topological expansion in which graphs with handles and boundaries are suppressed.Comment: Lattice2001(theorydevelop), poster by O. Baer and talk by B. Schlittgen, 6 page

Capitalism and natural rights: Marx, Locke and the moral justification of capitalism: inaugural lecture delivered at Rhodes University

Inaugural lecture delivered at Rhodes UniversityRhodes University Libraries (Digitisation)ONE of the commonplaces among political philosophers and theorists is the contempt with which Marx regarded Natural Rights theory. In 1843 he wrote that "the so-called rights of man, the droit de l'homme as distinct from the droit du citoyen, are nothing but the rights of a member of civil society, that is the rights of egoistic man, of man separated from other men and from the community." And again "the real man is recognised only in the shape of the egoistic individual, the true man is recognised only in the shape of the abstract citoyen."1 Marx saw Natural Rights as means for the justification of capitalism, and so, as justifying inequalities of wealth and property-ownership. And of course it is true that many writers, in supporting Natural Rights, have stressed, as Stuart Brown expresses it, that "They are the rights of a man to the protection of what is in his interest. The moral interests of one man may differ radically from those of another. Different men may have radically different needs and capacities. And these differences, in conjunction with unavoidable differences in opportunity, produce differences in estate. "2 Expressions of this kind make clear the point of Marx's critique. I wish tonight to argue and to attempt to establish two main theses. The first is that, despite Marx's expressed attitudes to Natural Rights, his own theory of capitalism cannot easily be disentangled from Natural Rights theory, and, if my argument is right, it in fact depends upon it. Secondly, I shall try to show, through an examination of the theories of John Locke, that if Natural Rights theory is to be taken seriously, it is at odds with the very capitalist theory which it is generally taken to support, and that Natural Rights cannot therefore provide an adequate under-pinning of capitalism, at least not without generating self-contradictions within the theory of Natural Rights. If the arguments which I shall present are right, I shall hope to have established what might be termed two paradoxes

Astrophysical S-factors for fusion reactions involving C, O, Ne and Mg isotopes

Using the Sao Paulo potential and the barrier penetration formalism we have calculated the astrophysical factor S(E) for 946 fusion reactions involving stable and neutron-rich isotopes of C, O, Ne, and Mg for center-of-mass energies E varying from 2 MeV to 18-30 MeV (covering the range below and above the Coulomb barrier). We have parameterized the energy dependence S(E) by an accurate universal 9-parameter analytic expression and present tables of fit parameters for all the reactions. We also discuss the reduced 3-parameter version of our fit which is highly accurate at energies below the Coulomb barrier, and outline the procedure for calculating the reaction rates. The results can be easily converted to thermonuclear or pycnonuclear reaction rates to simulate various nuclear burning phenomena, in particular, stellar burning at high temperatures and nucleosynthesis in high density environments.Comment: 30 pages including 11 tables, 4 figures, ADNDT, accepte

QCD as a Quantum Link Model

QCD is constructed as a lattice gauge theory in which the elements of the link matrices are represented by non-commuting operators acting in a Hilbert space. The resulting quantum link model for QCD is formulated with a fifth Euclidean dimension, whose extent resembles the inverse gauge coupling of the resulting four-dimensional theory after dimensional reduction. The inclusion of quarks is natural in Shamir's variant of Kaplan's fermion method, which does not require fine-tuning to approach the chiral limit. A rishon representation in terms of fermionic constituents of the gluons is derived and the quantum link Hamiltonian for QCD with a U(N) gauge symmetry is expressed in terms of glueball, meson and constituent quark operators. The new formulation of QCD is promising both from an analytic and from a computational point of view.Comment: 27 pages, including three figures. ordinary LaTeX; Submitted to Nucl. Phys.

QUANTIFYING THE COST OF SUBSTANDARD PATENTS: SOME PRELIMINARY EVIDENCE

The purpose of patent policy is to balance the incentive to invent against the ability of the economy to utilize and incorporate new inventions and innovations. Substandard patents that upset this balance impose deadweight losses and other costs on the economy. In this paper, we examine some of the deadweight losses that result from granting substandard patents in the United States. Under plausible assumptions, we find that the economic losses resulting from the grant of substandard patents can reach $21 billion per year by deterring valid research with an additional deadweight loss from litigation and administrative costs of$4.5 billion annually. This brings the total deadweight loss created by our dented patent system to be at least $25.5 billion annually. These estimates may be viewed as conservative because they do not take into account other economic costs from our existing patent system, such as the consumer welfare losses from granting monopoly rents to patent holders that have not, in the end, invented a novel product, or the full social value of the innovations lost

A quantum Monte Carlo algorithm realizing an intrinsic relaxation

We propose a new quantum Monte Carlo algorithm which realizes a relaxation intrinsic to the original quantum system. The Monte Carlo dynamics satisfies the dynamic scaling relation $\tau\sim \xi^z$ and is independent of the Trotter number. Finiteness of the Trotter number just appears as the finite-size effect. An infinite Trotter number version of the algorithm is also formulated, which enables us to observe a true relaxation of the original system. The strategy of the algorithm is a compromise between the conventional worldline local flip and the modern cluster loop flip. It is a local flip in the real-space direction and is a cluster flip in the Trotter direction. The new algorithm is tested by the transverse-field Ising model in two dimensions. An accurate phase diagram is obtained.Comment: 9 pages, 4 figure

Ultrafast supercontinuum spectroscopy of carrier multiplication and biexcitonic effects in excited states of PbS quantum dots

We examine the multiple exciton population dynamics in PbS quantum dots by ultrafast spectrally-resolved supercontinuum transient absorption (SC-TA). We simultaneously probe the first three excitonic transitions over a broad spectral range. Transient spectra show the presence of first order bleach of absorption for the 1S_h-1S_e transition and second order bleach along with photoinduced absorption band for 1P_h-1P_e transition. We also report evidence of the one-photon forbidden 1S_{h,e}-1P_{h,e} transition. We examine signatures of carrier multiplication (multiexcitons for the single absorbed photon) from analysis of the first and second order bleaches, in the limit of low absorbed photon numbers (~ 10^-2), at pump energies from two to four times the semiconductor band gap. The multiexciton generation efficiency is discussed both in terms of a broadband global fit and the ratio between early- to long-time transient absorption signals.. Analysis of population dynamics shows that the bleach peak due to the biexciton population is red-shifted respect the single exciton one, indicating a positive binding energy.Comment: 16 pages, 5 figure