Genome-wide expression patterns and the genetic architecture of a fundamental social trait.

Explaining how interactions between genes and the environment influence social behavior is a fundamental research goal, yet there is limited relevant information for species exhibiting natural variation in social organization. The fire ant Solenopsis invicta is characterized by a remarkable form of social polymorphism, with the presence of one or several queens per colony and the expression of other phenotypic and behavioral differences being completely associated with allelic variation at a single Mendelian factor marked by the gene Gp-9. Microarray analyses of adult workers revealed that differences in the Gp-9 genotype are associated with the differential expression of an unexpectedly small number of genes, many of which have predicted functions, implying a role in chemical communication relevant to the regulation of colony queen number. Even more surprisingly, worker gene expression profiles are more strongly influenced by indirect effects associated with the Gp-9 genotypic composition within their colony than by the direct effect of their own Gp-9 genotype. This constitutes an unusual example of an "extended phenotype" and suggests a complex genetic architecture with a single Mendelian factor, directly and indirectly influencing the individual behaviors that, in aggregate, produce an emergent colony-level phenotype

Effective action and density functional theory

The effective action for the charge density and the photon field is proposed as a generalization of the density functional. A simple definition is given for the density functional, as the functional Legendre transform of the generator functional of connected Green functions for the density and the photon field, offering systematic approximation schemes. The leading order of the perturbation expansion reproduces the Hartree-Fock equation. A renormalization group motivated method is introduced to turn on the Coulomb interaction gradually and to find corrections to the Hartree-Fock and the Kohn-Sham schemes.Comment: New references and a numerical algorithm added, to appear in Phys. Rev. B. 30 pages, no figure

Coherent particle production in collisions of relativistic nuclei

Here we give the results of our study of features of dense groups, or spikes, of particles produced in Mg-Mg and C-Cu collisions at, respectively, 4.3 and 4.5 GeV/c/nucleon aimed to search for a coherent, Cerenkov-like, mechanism of hadroproduction. We investigate the distributions of spike centers and, for Mg-Mg interactions, the energy spectra of negatively charged particles in spikes. The spike-center distributions are obtained to exhibit the structure expected from coherent gluon-jet emission dynamics. This structure is similar in both cases considered, namely for all charged and negatively charged particles, and is also similar to that observed recently for all-charged-particle spikes in hadronic interactions. The energy distribution within spikes is found to have a significant peak over the inclusive background, while the inclusive spectrum shows exponential decrease with two characteristic values of average kinetic energy. The value of the peak energy and its width are in a good agreement with those expected for pions produced in a nuclear medium in the framework of the Cerenkov quantum approach. The peak energy obtained is consistent with the value of the cross-section maximum observed in coincidence nucleon-nucleus interaction experiments.Comment: 8 pages, 5 figures. Invited talk presented by E.S. at the 9th International Workshop on Multiparticle Production: New Frontiers in Soft Physics and Correlations on the Threshold of the Third Millenium, Turin, Italy, June 12 - 17, 200

Critical Exponents for Three-Dimensional Superfluid--Bose-Glass Phase Transition

The critical phenomenon of the zero temperature superfluid--Bose-glass phase transition for hard-core bosons on a three-dimensional disordered lattice is studied using a quantum real-space renormalization-group method. The correlation-length exponent $\nu$ and the dynamic exponent z are computed. The critical exponent z is found to be 2.5 for compressible states and 1.3 for incompressible states. The exponent $\nu$ is shown to be insensitive to z as that in the two-dimensional case, and has value roughly equal to 1.Comment: 11 pages, REVTE

The floor in the interplanetary magnetic field: Estimation on the basis of relative duration of ICME observations in solar wind during 1976-2000

To measure the floor in interplanetary magnetic field and estimate the time- invariant open magnetic flux of Sun, it is necessary to know a part of magnetic field of Sun carried away by CMEs. In contrast with previous papers, we did not use global solar parameters: we identified different large-scale types of solar wind for 1976-2000 interval, obtained a fraction of interplanetary CMEs (ICMEs) and calculated magnitude of interplanetary magnetic field B averaged over 2 Carrington rotations. The floor of magnetic field is estimated as B value at solar cycle minimum when the ICMEs were not observed and it was calculated to be 4,65 \pm 6,0 nT. Obtained value is in a good agreement with previous results.Comment: 10 pages, 2 figures, submitted in GR

Co-pyrolysis of waste tyre and pine bark: study of reaction kinetics and mechanisms

Thermal processing of waste tyre and biomass through pyrolysis and gasification provides a promising pathway to address issues raised by anthropogenic activities including energy security, waste management and environmental sustainability. The study of the kinetics underlying the decomposition of the waste tyre and biomass blend through pyrolysis is an essential step to understand their further reactions in the reforming/cracking stage and to optimize their use. Kinetics analysis of the thermal decomposition of the waste tyre and pine bark with mass blend ratios of 1:0, 3:1, 1:1, 1:3 and 0:1 was investigated using thermogravimetric analysis. Results indicated that the change in heating rates from 10 to 40 K/min with an increment of 10 K/min caused a shift in differential thermogravimetry curves of all the samples to a higher temperature. To evaluate the possible interaction between waste tyre and pine bark in the blended samples, the difference in the weight loss (Δw) was calculated. Occurrence of positive synergetic interaction in terms of increased weight loss between waste tyre and pine bark at different blend ratios varied with the variation in heating rate. Activation energy and pre-exponential factor for different blend ratios were calculated using model fitting method (i.e. Coats-Redfern) and iso-conversional methods (i.e. FWO, KAS and Friedman) as well as combined kinetic analysis. Based on iso-conversional methods and combined kinetic analysis, the single waste tyre has higher activation energy than the single pine bark sample. However, waste tyre and pine bark blend samples with mass ratios of 3:1, 1:1 and 1:3 showed lower activation energy than waste tyre, signifying the benefits of using pine bark in blend samples. The maximum synergetic interaction in terms of lowest activation energy was reported with the use of the waste tyre and pine bark with a mass blend ratio of 3:1. The reaction mechanisms of WT1PB0, WT3PB1, WT1PB1, WT1PB3 and WT0PB1 were evaluated using the Sestak Berggren model and as follows; α−1.866(1−α)1.000[−ln(1−α)]−2.276, α−1.171(1−α)1.000[−ln(1−α)]−3.007, α1.765(1−α)1.000[−ln(1−α)]−5.381, α−2.324(1−α)2.913[−ln(1−α)]−1.272 and α−7.735(1−α)5.658[−ln(1−α)]5.594, respectively. The results of the current study will contribute to the knowledge of expanding waste disposal options and provide essential information for the development of an energy sustainable system

Solving 2D-pattern matching with networks of picture processors

We propose a solution based on networks of picture processors to the problem of picture pattern matching. The network solving the problem can be informally described as follows: it consists of two subnetworks, one of them extracts simultaneously all subpictures of the same size from the input picture and sends them to the second subnetwork. The second subnetwork checks whether any of the received pictures is identical to the pattern. We present an efficient solution based on networks with evolutionary processors only, for patterns with at most three rows or columns. Afterwards, we present a solution based on networks containing both evolutionary and hiding processors running in O(n+m+kl+k) computational (processing and communication) steps, where the input picture and the pattern are of size (n,m) and (k,l), respectively

Density functional study of Aun_n (n=2-20) clusters: lowest-energy structures and electronic properties

We have investigated the lowest-energy structures and electronic properties of the Au$_n$(n=2-20) clusters based on density functional theory (DFT) with local density approximation. The small Au$_n$ clusters adopt planar structures up to n=6. Tabular cage structures are preferred in the range of n=10-14 and a structural transition from tabular cage-like structure to compact near-spherical structure is found around n=15. The most stable configurations obtained for Au$_{13}$ and Au$_{19}$ clusters are amorphous instead of icosahedral or fcc-like, while the electronic density of states sensitively depend on the cluster geometry. Dramatic odd-even alternative behaviors are obtained in the relative stability, HOMO-LUMO gaps and ionization potentials of gold clusters. The size evolution of electronic properties is discussed and the theoretical ionization potentials of Au$_n$ clusters compare well with experiments.Comment: 6 pages, 7 figure

Kondo effect in a Luttinger liquid: nonuniversality of the Wilson ratio

Using a precise coset Ising-Bose representation, we show how backscattering of electrons off a magnetic impurity destabilizes the two-channel Kondo fixed point and drives the system to a new fixed point, in agreement with previous results. In addition, we verify the scaling proposed by Furusaki and Nagaosa and prove that the other possible critical fixed point, namely the local Fermi liquid class, is not completely universal when backscattering is included because the Wilson ratio is not well-defined in the spinon basis.Comment: 4 pages, RevTeX; to appear in Physical Review