Reverse geometric engineering of singularities

One can geometrically engineer supersymmetric field theories theories by placing D-branes at or near singularities. The opposite process is described, where one can reconstruct the singularities from quiver theories. The description is in terms of a noncommutative quiver algebra which is constructed from the quiver diagram and the superpotential. The center of this noncommutative algebra is a commutative algebra, which is the ring of holomorphic functions on a variety V. If certain algebraic conditions are met, then the reverse geometric engineering produces V as the geometry that D-branes probe. It is also argued that the identification of V is invariant under Seiberg dualities.Comment: 17 pages, Latex. v2: updates reference

Bose-stimulated scattering off a cold atom trap

The angle and temperature dependence of the photon scattering rate for Bose-stimulated atom recoil transitions between occupied states is compared to diffraction and incoherent Rayleigh scattering near the Bose-Einstein transition for an optically thin trap in the limit of large particle number, N. Each of these processes has a range of angles and temperatures for which it dominates over the others by a divergent factor as N->oo.Comment: 18 pages (REVTeX), no figure

Hierarchical strategies for efficient fault recovery on the reconfigurable PAnDA device

A novel hierarchical fault-tolerance methodology for reconfigurable devices is presented. A bespoke multi-reconfigurable FPGA architecture, the programmable analogue and digital array (PAnDA), is introduced allowing fine-grained reconfiguration beyond any other FPGA architecture currently in existence. Fault blind circuit repair strategies, which require no specific information of the nature or location of faults, are developed, exploiting architectural features of PAnDA. Two fault recovery techniques, stochastic and deterministic strategies, are proposed and results of each, as well as a comparison of the two, are presented. Both approaches are based on creating algorithms performing fine-grained hierarchical partial reconfiguration on faulty circuits in order to repair them. While the stochastic approach provides insights into feasibility of the method, the deterministic approach aims to generate optimal repair strategies for generic faults induced into a specific circuit. It is shown that both techniques successfully repair the benchmark circuits used after random faults are induced in random circuit locations, and the deterministic strategies are shown to operate efficiently and effectively after optimisation for a specific use case. The methods are shown to be generally applicable to any circuit on PAnDA, and to be straightforwardly customisable for any FPGA fabric providing some regularity and symmetry in its structure

Proof of principle : the adaptive geometry of social foragers

Acknowledgments We thank Cape Nature for permission to undertake the study. We thank Dr Matt Grove and two anonymous referees for comments and suggestions that improved the manuscript substantially. This research was funded by grants from the Leakey Foundation, National Science and Engineering Research Council, Canada to S.P.H. and L.B., and by the National Research Foundation, South Africa to S.P.H. His co-authors dedicate this paper to the memory of P.M.R.C. The authors declare no competing interests.Peer reviewedPostprin

Partial N=2→N=1{\cal N}=2 \to {\cal N}=1 supersymmetry breaking and gravity deformed chiral rings

We present a derivation of the chiral ring relations, arising in ${\cal N}=1$ gauge theories in the presence of (anti-)self-dual background gravitational field $G_{\alpha\beta\gamma}$ and graviphoton field strength $F_{\alpha\beta}$. These were previously considered in the literature in order to prove the relation between gravitational F-terms in the gauge theory and coefficients of the topological expansion of the related matrix integral. We consider the spontaneous breaking of ${\cal N} =2$ to ${\cal N} =1$ supergravity coupled to vector- and hyper-multiplets, and take a rigid limit which keeps a non-trivial $G_{\alpha\beta\gamma}$ and $F_{\alpha\beta}$ with a finite supersymmetry breaking scale. We derive the resulting effective, global, ${\cal N}=1$ theory and show that the chiral ring relations are just a consequence of the standard ${\cal N}=2$ supergravity Bianchi identities . We can also obtain models with matter in different representations and in particular quiver theories. We also show that, in the presence of non-trivial $F_{\alpha\beta}$, consistency of the Konishi-anomaly loop equations with the chiral ring relations, demands that the gauge kinetic function and the superpotential, a priori unrelated for an ${\cal N}=1$ theory, should be derived from a prepotential, indicating an underlying ${\cal N}=2$ structure.Comment: 42 pages, uses JHEP.cls;v2: typos corrected and references adde

Phylogeny of the Subfamilies of Ichneumonidae (Hymenoptera)

A combined morphological and molecular phylogenetic analysis was performed to evaluate the subfamily relationships of the parasitoid wasp family Ichneumonidae (Hymenoptera). Data were obtained by coding 135 morphological and 6 biological characters for 131 exemplar species of ichneumonids and 3 species of Braconidae (the latter as outgroups). The species of ichneumonids represent all of the 42 currently recognized subfamilies. In addition, molecular sequence data (cytochrome oxidase I “DNA barcoding” region, the D2 region of 28S rDNA and part of the F2 copy of elongation factor 1-alpha) were obtained from specimens of the same species that were coded for morphology (1309 base pairs total). The data were analyzed using parsimony and Bayesian analyses. The parsimony analysis using all data recovered previ-ously recognized informal subfamily groupings (Pimpliformes, Ophioniformes, Ichneumoniformes), al-though the relationships of these three groups to each other differed from previous studies and some of the subfamily relationships within these groupings had not previously been suggested. Specifically, Ophioni-formes was the sister group to (Ichneumoniformes + Pimplformes), and Labeninae was placed near Ich-neumoniformes, not as sister group to all Ichneumonidae except Xoridinae. The parsimony analysis using only morphological characters was poorly resolved and did not recover any of the three informal subfamily groupings and very few of the relationships were similar to the total-evidence parsimony analysis. The mo-lecular-only parsimony analysis and both Bayesian analyses (total-evidence and molecular-only) recovered Pimpliformes, a restricted Ichneumoniformes grouping and many of the subfamily groupings recovered in the total-evidence parsimony analysis. A comparison and discussion of the results obtained by each phylo-genetic method and different data sets is provided. It is concluded that the molecular characters produced results that were relatively consistent with traditional, non-phylogenetic concepts of relationships between the ichneumonid subfamilies, whereas the morphological characters did not (at least not by themselves). The inclusion of both molecular and morphological characters using parsimony produced a topology that was the closest to the traditional subfamily relationships. The method of analysis did not greatly affect the overall topology for the molecular-only analyses, but there were differences between Bayesian and parsi-mony results for the total-evidence analyses (especially near the root of the tree). The Bayesian results did not seem to be altered very much by the inclusion of morphological characters, unlike in the parsimony analysis. In summary, the following groups were supported in multiple analyses regardless of the characters used or method of tree-building: Pimpliformes, higher Ophioniformes, higher Pimpliformes, (Claseinae + Pedunculinae), (Banchinae + Stilbopinae), Campopleginae, Cremastinae, Diplazontinae, Ichneumoninae (including Alomya), Labeninae, Ophioninae, Poemeniinae, Rhyssinae, and Tersilochinae sensu stricto. Conversely, Ctenopelmatinae and Tryphoninae were never recovered without inclusion of other taxa. Based on the hypothesis of relationships obtained by the total-evidence parsimony analysis, the following formal taxonomic changes are proposed: Alomyinae Förster (= Alomya Panzer and Megalomya Uchida) is once again synonymized with Ichneumoninae and is now considered a tribe (Alomyini rev. stat.); and Notostilbops Townes is transferred from Stilbopinae to Banchinae, tribe Atrophini

Polar Bear Conservation in Canada: Defining the Policy Problems

Conservation of polar bears (Ursus maritimus) in Canada is based on the goals and principles of the 1973 International Agreement on the Conservation of Polar Bears and Their Habitat, and has long been considered an exemplar of science-based wildlife management. However, accelerating social and ecological changes in the Arctic raise questions about the polar bear management regime’s ability to adapt successfully to new challenges. We apply the analytic framework of the policy sciences to develop a comprehensive orientation to this evolving situation, and we suggest possible ways to define and advance shared goals of stakeholders and other participants. We conclude that the decision process in polar bear management does not sufficiently foster identification and securing of common interests among participants who express multiple, competing perspectives in an arena that has been increasingly fragmented and symbolically charged by issues such as the recent listing of polar bears under the U.S. Endangered Species Act. The fundamental challenge for polar bear conservation in Canada is to design a better decision process so that it can constructively reconcile the various perspectives, demands, and expectations of stakeholders.Au Canada, la conservation des ours polaires (Ursus maritimus) respecte les objectifs et les principes de l’Accord international sur la conservation des ours blancs et leur habitat de 1973, qui est considéré depuis longtemps comme un modèle de gestion de la faune fondée sur la science. Cependant, l’évolution de plus en plus rapide des changements d’ordre social et écologique dans l’Arctique a pour effet de soulever des questions sur l’aptitude du régime de gestion de l’ours polaire à bien s’adapter aux nouveaux défis. Nous utilisons le cadre de référence analytique de la science des politiques pour aboutir à une orientation exhaustive de cette situation en pleine évolution, et nous suggérons des manières possibles de définir et de formuler des objectifs partagés par les parties prenantes et d’autres participants. Nous concluons que le processus de décision en matière de gestion de l’ours polaire n’encourage pas suffisamment l’identification et l’engagement d’intérêts communs entre les participants qui expriment des perspectives multiples et concurrentes dans un domaine de plus en plus fragmenté et symboliquement caractérisé par des enjeux tels que la liste récente d’ours polaires en vertu de la loi américaine sur les espèces en voie de disparition (U.S. Endangered Species Act). Le défi fondamental en ce qui a trait à la conservation des ours polaires au Canada consiste à concevoir un meilleur processus de décision pouvant réconcilier, de manière constructive, les diverses perspectives, exigences et attentes des parties prenantes

Ricci-flat deformation of orbifolds and localized tachyonic modes

We study Ricci-flat deformations of orbifolds in type II theory. We obtain a simple formula for mass corrections to the twisted modes due to the deformations, and apply it to originally tachyonic and massless states in several examples. In the case of supersymmetric orbifolds, we find that tachyonic states appear when the deformation breaks all the supersymmetries. We also study nonsupersymmetric orbifolds C^2/Z_{2N(2N+1)}, which is T-dual to N type 0 NS5-branes. For N>=2, we compute mass corrections for states, which have string scale tachyonic masses. We find that the corrected masses coincide to ones obtained by solving the wave equation for the tachyon field in the smeared type 0 NS5-brane background geometry. For N=1, we show that the unstable mode representing the bubble creation is the unique tachyonic mode.Comment: 20 pages, minor collection

Formation of gold colloids using thioether derivatives as stabilizing ligands

Thioethers were used as adsorbates for preparing gold nanoparticles. Different thioether derivatives having from 1 to 4 thioether functionalities were synthesized. Colloids were prepared in a two-phase system, and characterized by 1H NMR and transmission electron microscopy (TEM). The stability of colloids protected by thioethers increases with the number of ligands per molecule. Monothioethers need longer chain lengths or costabilization by (oct)4NBr in order to give stable, redispersible gold colloids. Gold colloids stabilized by the bis(thioether) 5 could not be redispersed after precipitation. Colloids stabilized by the tris(thioether) 6 were only formed at elevated temperature (60°C) indicating the need of chain reorientation for attaining stable colloids. Tris(thioether) 7 gave stable colloids at room temperature, which could be redispersed even after precipitation. Tetrakis(thioether) 8 gave the smallest particle size and narrowest size distributio