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Dimer models from mirror symmetry and quivering amoebae
Dimer models are 2-dimensional combinatorial systems that have been shown to encode the gauge groups, matter content and tree-level superpotential of the world-volume quiver gauge theories obtained by placing D3-branes at the tip of a singular toric Calabi-Yau cone. In particular the dimer graph is dual to the quiver graph. However, the string theoretic explanation of this was unclear. In this paper we use mirror symmetry to shed light on this: the dimer models live on a T^2 subspace of the T^3 fiber that is involved in mirror symmetry and is wrapped by D6-branes. These D6-branes are mirror to the D3-branes at the singular point, and geometrically encode the same quiver theory on their world-volume
Maternal circadian rhythms and the programming of adult health and disease
The in utero environment is inherently rhythmic, with the fetus subjected to circadian changes in temperature, substrates and various maternal hormones. Meanwhile, the fetus is developing an endogenous circadian timing system, preparing for life in an external environment where light, food availability and other environmental factors change predictably and repeatedly every 24 hours. In humans, there are many situations that can disrupt circadian rhythms, including shift work, international travel, insomnias and circadian rhythm disorders (e.g., advanced/delayed sleep phase disorder), with a growing consensus that this chronodisruption can have deleterious consequences for an individual's health and wellbeing. However, the impact of chronodisruption during pregnancy on the health of both the mother and fetus is not well understood. In this review we outline circadian timing system ontogeny in mammals, and examine emerging research from animal models demonstrating long term negative implications for progeny health following maternal chronodisruption during pregnancy.Tamara J. Varcoe, X Kathryn L. Gatford, and David J. Kennawa
Mesonic Chiral Rings in Calabi-Yau Cones from Field Theory
We study the half-BPS mesonic chiral ring of the N=1 superconformal quiver
theories arising from N D3-branes stacked at Y^pq and L^abc Calabi-Yau conical
singularities. We map each gauge invariant operator represented on the quiver
as an irreducible loop adjoint at some node, to an invariant monomial, modulo
relations, in the gauged linear sigma model describing the corresponding bulk
geometry. This map enables us to write a partition function at finite N over
mesonic half-BPS states. It agrees with the bulk gravity interpretation of
chiral ring states as cohomologically trivial giant gravitons. The quiver
theories for L^aba, which have singular base geometries, contain extra
operators not counted by the naive bulk partition function. These extra
operators have a natural interpretation in terms of twisted states localized at
the orbifold-like singularities in the bulk.Comment: Latex, 25pgs, 12 figs, v2: minor clarification
Probing the Space of Toric Quiver Theories
We demonstrate a practical and efficient method for generating toric Calabi-Yau quiver theories, applicable to both D3 and M2 brane world-volume physics. A new analytic method is presented at low order parametres and an algorithm for the general case is developed which has polynomial complexity in the number of edges in the quiver. Using this algorithm, carefully implemented, we classify the quiver diagram and assign possible superpotentials for various small values of the number of edges and nodes. We examine some preliminary statistics on this space of toric quiver theories
Rapidly alternating photoperiods disrupt central and peripheral rhythmicity and decrease plasma glucose, but do not affect glucose tolerance or insulin secretion in sheep
Disrupting circadian rhythms in rodents perturbs glucose metabolism and increases adiposity. To determine whether these effects occur in a large diurnal animal, we assessed the impact of circadian rhythm disruption upon metabolic function in sheep. Adult ewes (n = 7) underwent 3 weeks of a control 12 h light-12 h dark photoperiod, followed by 4 weeks of rapidly alternating photoperiods (RAPs) whereby the time of light exposure was reversed twice each week. Measures of central (melatonin secretion and core body temperature) and peripheral rhythmicity (clock and metabolic gene expression in skeletal muscle) were obtained over 24 h in both conditions. Metabolic homeostasis was assessed by glucose tolerance tests and 24 h glucose and insulin profiles. Melatonin and core body temperature rhythms resynchronized within 2 days of the last photoperiod shift. High-amplitude Bmal1, Clock, Nr1d1, Cry2 and Per3 mRNA rhythms were apparent in skeletal muscle, which were phase advanced by up to 3.5 h at 2 days after the last phase shift, whereas Per1 expression was downregulated at this time. Pparα, Pgc1α and Nampt mRNA were constitutively expressed in both conditions. Nocturnal glucose concentrations were reduced following chronic phase shifts (zeitgeber time 0, -5.5%; zeitgeber time 12, -2.9%; and zeitgeber time 16, -5.7%), whereas plasma insulin, glucose tolerance and glucose-stimulated insulin secretion were not altered. These results demonstrate that clock gene expression within ovine skeletal muscle oscillates over 24 h and responds to changing photoperiods. However, metabolic genes which link circadian and metabolic clocks in rodents were arrhythmic in sheep. Differences may be due to the ruminant versus monogastric digestive organization in each species. Together, these results demonstrate that despite disruptions to central and peripheral rhythmicity following exposure to rapidly alternating photoperiods, there was minimal impact on glucose homeostasis in the sheep.Tamara J. Varcoe, Kathryn L. Gatford, Athena Voultsios, Mark D. Salkeld, Michael J. Boden, Leewen Rattanatray and David J. Kennawa
Survival through networks: the 'grip' of the administrative links in the Russian post-Soviet context
© 2014 Taylor & Francis. Based on an analysis of the post-Soviet transformation experience of four defence sector organizations in a Russian region where the defence sector occupies a substantial part of the local economy, this article develops a typology of network relationships: Grooved Inter-relationship Patterns (Grâip) networks and Fluid Inter-relationship Patterns (Flâip) networks. This typology can be applied to a range of transition/emerging market and low system trust contexts. Grâip networks, in this case, represent the persisting legacy of the Soviet command-administrative system. Flâip networks are here an attempt by the defence companies to link into the civilian supply chains of a developing market economy. This article argues that Grâip networks had and still have a crucial role to play in Russian enterprisesâ survival and development
Counting Orbifolds
We present several methods of counting the orbifolds C^D/Gamma. A
correspondence between counting orbifold actions on C^D, brane tilings, and
toric diagrams in D-1 dimensions is drawn. Barycentric coordinates and scaling
mechanisms are introduced to characterize lattice simplices as toric diagrams.
We count orbifolds of C^3, C^4, C^5, C^6 and C^7. Some remarks are made on
closed form formulas for the partition function that counts distinct orbifold
actions.Comment: 69 pages, 9 figures, 24 tables; minor correction
Brane Tilings and Specular Duality
We study a new duality which pairs 4d N=1 supersymmetric quiver gauge
theories. They are represented by brane tilings and are worldvolume theories of
D3 branes at Calabi-Yau 3-fold singularities. The new duality identifies
theories which have the same combined mesonic and baryonic moduli space,
otherwise called the master space. We obtain the associated Hilbert series
which encodes both the generators and defining relations of the moduli space.
We illustrate our findings with a set of brane tilings that have reflexive
toric diagrams.Comment: 42 pages, 16 figures, 5 table
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