3,048 research outputs found
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
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
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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
Sprouty1 regulates reversible quiescence of a self-renewing adult muscle stem cell pool during regeneration.
Satellite cells are skeletal muscle stem cells capable of self-renewal and differentiation after transplantation, but whether they contribute to endogenous muscle fiber repair has been unclear. The transcription factor Pax7 marks satellite cells and is critical for establishing the adult satellite cell pool. By using a lineage tracing approach, we show that after injury, quiescent adult Pax7(+) cells enter the cell cycle; a subpopulation returns to quiescence to replenish the satellite cell compartment, while others contribute to muscle fiber formation. We demonstrate that Sprouty1 (Spry1), a receptor tyrosine kinase signaling inhibitor, is expressed in quiescent Pax7(+) satellite cells in uninjured muscle, downregulated in proliferating myogenic cells after injury, and reinduced as Pax7(+) cells re-enter quiescence. We show that Spry1 is required for the return to quiescence and homeostasis of the satellite cell pool during repair. Our results therefore define a role for Spry1 in adult muscle stem cell biology and tissue repair
Planting Date, Hybrid Maturity, and Weather Effects on Maize Yield and Crop Stage
Unfavorable weather conditions frequently cause farmers to plant maize (Zea mays L.) outside the optimum planting timeframe. We analyzed maize yield and phenology from a multilocation, year, hybrid relative maturity, and planting date experiment performed in Iowa, USA. Our objectives were to determine the optimum combination of planting date and relative maturity to maximize maize grain yield per environment and to elucidate the risk associated with the use of âfull-season hybridsâ when planting occurs beyond the optimum planting date. Analysis of variance (ANOVA) attributed 70% of the variability in grain yield to planting date and only 10% to relative maturity indicating that short and full-season hybrid relative maturities produced similar grain yields regardless of when they were planted as long as the crops reached maturity before harvesting. Our analysis indicated time to silking is a good indication of expected yield potential with a critical time (beyond which yield is reduced) to be 23 July for Iowa. Furthermore, we found that a minimum growing degree accumulation of 648°Cday during the grain-filling period maximized maize yield. Overall, this study brings new results to assist decision making regarding planting date by hybrid relative maturity across Iowa
Switching of +/-360deg domain wall states in a nanoring by an azimuthal Oersted field
We demonstrate magnetic switching between two domain wall vortex
states in cobalt nanorings, which are candidate magnetic states for robust and
low power MRAM devices. These 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
Inhibitory Deficits in reading disability depend on subtype: guessers but not spellers
In this study, children with the guessing subtype of dyslexia (who read fast and inaccurately) were compared with children with the spelling subtype (who read slowly and accurately) on three aspects of executive functioning (EF): response inhibition, susceptibility to interference from irrelevant information, and planning. It was found that guessers were impaired in their ability to inhibit inappropriate responding on all tasks used to assess EF (the stop signal task, the Stroop task, and the Tower of London task). This raises the question of whether the specific reading disorder of guessers may be linked to the same executive deficits which underlie ADHD. In order to unite a fast/inaccurate reading style with executive deficiencies, an attempt is made to incorporate the concept of executive control into models of lexical activation
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