The AdS/CFT/Unparticle Correspondence

We examine the correspondence between the anti-de Sitter (AdS) description of conformal field theories (CFTs) and the unparticle description of CFTs. We show how unparticle actions are equivalent to holographic boundary actions for fields in AdS, and how massive unparticles provide a new type of infrared cutoff that can be simply implemented in AdS by a soft breaking of conformal symmetry. We also show that processes involving scalar unparticles with dimensions d_s<2 or fermion unparticles with dimensions d_f<5/2 are insensitive to ultraviolet cutoff effects. Finally we show that gauge interactions for unparticles can be described by bulk gauge interactions in AdS and that they correspond to minimal gauging of the non-local effective action, and we compute the fermion unparticle production cross-section.Comment: 26 pages, 1 figur

Analysis of Antarctic glacigenic sediment provenance through geochemical and petrologic applications

The number of provenance studies of glacigenic sediments in Antarctica has increased dramatically over the past decade, providing an enhanced understanding of ice sheet history and dynamics, along with the broader geologic history. Such data have been used to assess glacial erosion patterns at the catchment scale, flow path reconstructions over a wide range of scales, and ice sheet fluctuations indicated by iceberg rafted debris in circumantarctic glacial marine sediments. It is notable that even though most of the bedrock of the continent is ice covered and inaccessible, provenance data can provide such valuable information about Antarctic ice and can even be used to infer buried rock types along with their geo- and thermochronologic history. Glacigenic sediments provide a broader array of provenance analysis opportunities than any other sediment type because of their wide range of grain sizes, and in this paper we review methods and examples from all size fractions that have been applied to the Antarctic glacigenic sedimentary record. Interpretations of these records must take careful consideration of the choice of analytical methods, uneven patterns of erosion, and spatial variability in sediment transport and rock types, which all may lead to a preferential identification of different elements of sources in the provenance analyses. Because of this, we advocate a multi-proxy approach and highlight studies that demonstrate the value of selecting complementary provenance methods

Local states of free bose fields

These notes contain an extended version of lectures given at the ``Summer School on Large Coulomb Systems'' in Nordfjordeid, Norway, in august 2003. They furnish a short introduction to the theory of quantum harmonic systems, or free bose fields. The main issue addressed is the one of local states. I will adopt the definition of Knight of ``strictly local excitation of the vacuum'' and will then state and prove a generalization of Knight's Theorem which asserts that finite particle states cannot be perfectly localized. It will furthermore be explained how Knight's a priori counterintuitive result can be readily understood if one remembers the analogy between finite and infinite dimensional harmonic systems alluded to above. I will also discuss the link between the above result and the so-called Newton-Wigner position operator thereby illuminating, I believe, the difficulties associated with the latter. I will in particular argue that those difficulties do not find their origin in special relativity or in any form of causality violation, as is usually claimed

Local Finite Element Approximation of Sobolev Differential Forms

We address fundamental aspects in the approximation theory of vector-valued finite element methods, using finite element exterior calculus as a unifying framework. We generalize the Cl\'ement interpolant and the Scott-Zhang interpolant to finite element differential forms, and we derive a broken Bramble-Hilbert Lemma. Our interpolants require only minimal smoothness assumptions and respect partial boundary conditions. This permits us to state local error estimates in terms of the mesh size. Our theoretical results apply to curl-conforming and divergence-conforming finite element methods over simplicial triangulations.Comment: 22 pages. Comments welcom

Cas9+ conditionally-immortalized macrophages as a tool for bacterial pathogenesis and beyond.

Macrophages play critical roles in immunity, development, tissue repair, and cancer, but studies of their function have been hampered by poorly-differentiated tumor cell lines and genetically-intractable primary cells. Here we report a facile system for genome editing in non-transformed macrophages by differentiating ER-Hoxb8 myeloid progenitors from Cas9-expressing transgenic mice. These conditionally immortalized macrophages (CIMs) retain characteristics of primary macrophages derived from the bone marrow yet allow for easy genetic manipulation and a virtually unlimited supply of cells. We demonstrate the utility of this system for dissection of host genetics during intracellular bacterial infection using two important human pathogens: Listeria monocytogenes and Mycobacterium tuberculosis

Chaos and unpredictability in evolutionary dynamics in discrete time

A discrete-time version of the replicator equation for two-strategy games is studied. The stationary properties differ from that of continuous time for sufficiently large values of the parameters, where periodic and chaotic behavior replace the usual fixed-point population solutions. We observe the familiar period-doubling and chaotic-band-splitting attractor cascades of unimodal maps but in some cases more elaborate variations appear due to bimodality. Also unphysical stationary solutions have unusual physical implications, such as uncertainty of final population caused by sensitivity to initial conditions and fractality of attractor preimage manifolds.Comment: 4 pages, 4 figure

Switching of +/-360deg domain wall states in a nanoring by an azimuthal Oersted field

We demonstrate magnetic switching between two $360^\circ$ domain wall vortex states in cobalt nanorings, which are candidate magnetic states for robust and low power MRAM devices. These $360^\circ$ domain wall (DW) or "twisted onion" states can have clockwise or counterclockwise circulation, the two states for data storage. Reliable switching between the states is necessary for any realistic device. We accomplish this switching by applying a circular Oersted field created by passing current through a metal atomic force microscope tip placed at the center of the ring. After initializing in an onion state, we rotate the DWs to one side of the ring by passing a current through the center, and can switch between the two twisted states by reversing the current, causing the DWs to split and meet again on the opposite side of the ring. A larger current will annihilate the DWs and create a perfect vortex state in the rings.Comment: 5 pages, 5 figure

Rapid shifts in Atta cephalotes fungus-garden enzyme activity after a change in fungal substrate (Attini, Formicidae)

Fungus gardens of the basidiomycete Leucocoprinus gongylophorus sustain large colonies of leaf-cutting ants by degrading the plant material collected by the ants. Recent studies have shown that enzyme activity in these gardens is primarily targeted toward starch, proteins and the pectin matrix associated with cell walls, rather than toward structural cell wall components such as cellulose and hemicelluloses. Substrate constituents are also known to be sequentially degraded in different sections of the fungus garden. To test the plasticity in the extracellular expression of fungus-garden enzymes, we measured the changes in enzyme activity after a controlled shift in fungal substrate offered to six laboratory colonies of Atta cephalotes. An ant diet consisting exclusively of grains of parboiled rice rapidly increased the activity of endo-proteinases and some of the pectinases attacking the backbone structure of pectin molecules, relative to a pure diet of bramble leaves, and this happened predominantly in the most recently established top sections of fungus gardens. However, fungus-garden amylase activity did not significantly increase despite the substantial increase in starch availability from the rice diet, relative to the leaf diet controls. Enzyme activity in the older, bottom sections of fungus gardens decreased, indicating a faster processing of the rice substrate compared to the leaf diet. These results suggest that leaf-cutting ant fungus gardens can rapidly adjust enzyme activity to provide a better match with substrate availability and that excess starch that is not protected by cell walls may be digested by the ants rather than by the fungus-garden symbiont

On the mechanism of diminished urinary carbon dioxide tension caused by amiloride

On the mechanism of diminished urinary carbon dioxide tension caused by amiloride. We investigated under both in vivo and in vitro conditions the mechanism whereby amiloride administration, a model of distal renal tubular acidosis in dogs, decreases the urine-to-blood PCO2 gradient (U-B PCO2) in alkaline urine. The results demonstrate that U-B PCO2 is reduced in amiloride-treated dogs as previously reported in rats. The reduction in U-B PCO2 could not be attributed to amiloride-induced reductions in urinary HCO-3 concentration since the reduction in U-B PCO2 was observed over the same range of urinary HCO-3 concentrations (150 to 250 mEq per liter) as that achieved prior to amiloride administration. U-B PCO2 correlated positively and linearly with urinary HCO-3 concentration both prior to (P < 0.001) and during amiloride infusion (P < 0.001). Amiloride administration significantly decreased the slope (Δ[U-B PCO2]/Δ[HCO-3]u) of the regression line (P < 0.005). The possibility that amiloride might lower urine PCO2 by catalyzing intraluminal dehydration of H2CO3 was excluded by demonstrating that amiloride does not possess carbonic anhydrase activity. The additional possibility that amiloride might facilitate dissipation of carbon dioxide gradients through diffusion (as reported for carbonic anhydrase) was excluded by in vitro studies of the effect of amiloride on carbon dioxide diffusion. These findings suggest that the U-B PCO2 lowering effect of amiloride is not caused by alterations in urinary [HCO-3, CO2 diffusibility, or alterations in the dehydration rate of H2CO3 thereby providing strong support for the interpretation that reductions in U-B PCO2 during amiloride administration represent an impairment in distal nephron hydrogen ion secretion.Sur le méchanisme de la diminution de la pression partielle de carbonique dans l'urine déterminée par l'amiloride. Nous avons examiné in vivo et in vitro le mécanisme par lequel l'administration d'amiloride, un modèle d'acidose tubulaire distale chez le chien, diminue le gradient urinesang de PCO2 (U-B PCO2) en urine alcaline. Les résultats démontrent que U-B PCO2 est réduit chez le chien traité par l'amiloride comme cela a été antérieurement montré chez le rat. Le diminution de U-B PCO2 ne peut pas être attribuée à la diminution de la concentration urinaire de HCO-3 déterminée par l'amiloride puisque la diminution de U-B PCO2 a été observée pour le même éventail de concentrations urinaires de HCO-3 (150 à 250 mEq par litre) que celui réalisé avant l'administration d'amiloride. U-B PCO2 est corrélé linéairement et positivement à la concentration urinaire de HCO-3 aussi bien avant (P < 0,001) que pendant la perfusion d'amiloride (P < 0,001). L'administration d'amiloride diminue régulièrement la pente (Δ[U-B PCO2]/Δ[HCO-3]u) de la droite de régression (P < 0,005). La possibilité que l'amiloride puisse diminuer la PCO2 urinaire en catalysant la déshydratation intraluminal de H2CO3 a été exclue par la démonstration de l'absence d'activité de type anhydrase carbonique de l'amiloride. La possibilité que l'amiloride puisse faciliter la dissipation par diffusion des gradients de carbonique a été exclue par des études in vitro. Ces constatations suggèrent que l'effet de l'amiloride de diminution de U-B PCO2 n'est pas lié à des modifications de [HCO-3] de l'urine, de la diffusibilité du carbonique, ou du débit de déshydratation de H2CO3, et par conséquent constituent un argument fort en faveur d'une altération de la sécrétion distale d'ion hydrogène

Imperfect Imitation Can Enhance Cooperation

The promotion of cooperation on spatial lattices is an important issue in evolutionary game theory. This effect clearly depends on the update rule: it diminishes with stochastic imitative rules whereas it increases with unconditional imitation. To study the transition between both regimes, we propose a new evolutionary rule, which stochastically combines unconditional imitation with another imitative rule. We find that, surprinsingly, in many social dilemmas this rule yields higher cooperative levels than any of the two original ones. This nontrivial effect occurs because the basic rules induce a separation of timescales in the microscopic processes at cluster interfaces. The result is robust in the space of 2x2 symmetric games, on regular lattices and on scale-free networks.Comment: 4 pages, 4 figure