The Intermediate Coupling Regime in the AdS/CFT Correspondence

The correspondence between the 't Hooft limit of N=4 super Yang-Mills theory and tree-level IIB superstring theory on AdS(5)xS(5) in a Ramond-Ramond background at values of lambda=g^2 N ranging from infinity to zero is examined in the context of unitarity. A squaring relation for the imaginary part of the holographic scattering of identical string fields in the two-particle channels is found, and a mismatch between weak and strong 't Hooft coupling is pointed out within the correspondence. Several interpretations and implications are proposed.Comment: 10 pages, LaTeX, reference adde

Exact low-energy effective actions for hypermultiplets in four dimensions

We consider the general hypermultiplet Low-Energy Effective Action (LEEA) that may appear in quantized, four-dimensional, N=2 supersymmetric, gauge theories, e.g. in the Coulomb and Higgs branches. Our main purpose is a description of the exact LEEA of n magnetically charged hypermultiplets. The hypermultiplet LEEA is given by the N=2 supersymmetric Non-Linear Sigma-Model (NLSM) with a 4n-dimensional hyper-K"ahler metric, subject to non-anomalous symmetries. Harmonic Superspace (HSS) and the NLSM isometries are very useful to constrain the hyper-K"ahler geometry of the LEEA. We use N=2 supersymmetric projections of HSS superfields to N=2 linear (tensor) O(2) and O(4) multiplets in N=2 Projective Superspace (PSS) to deduce the explicit form of the LEEA in some particular cases. As the by-product, a simple new classification of all multi-monopole moduli space metrics having su(2)_R symmetry is proposed in terms of real quartic polynomials of 2n variables, modulo Sp(n) transformations. The 4d hypermultiplet LEEA for n=2 can be encoded in terms of an elliptic curve.Comment: 60 pages, LaTeX, macros included, references adde

Response to Nauenberg's "Critique of Quantum Enigma: Physics Encounters Consciousness"

Nauenberg's extended critique of Quantum Enigma rests on fundamental misunderstandings.Comment: To be published in Foundations of Physic

Absolute Present, Zen and Schrödinger’s One Mind

Erwin Schrödinger holds a prominent place in the history of science primarily due to his crucial role in the development of quantum physics. What is perhaps lesser known are his insights into subject-object duality, consciousness and mind. He documented himself that these were influenced by the Upanishads, a collection of ancient Hindu spiritual texts. Central to his thoughts in this area is that Mind is only One and there is no separation between subject and object. This chapter aims to bridge Schrödinger’s view on One Mind with the teachings of Dōgen, a twelfth century Zen master. This bridge is formed by addressing the question of how time relates to One Mind, and subject-object duality. Schrödinger describes the experience of One Mind to be like a timeless now, whereas subject-object duality involves a linear continuum of time. We show how these differing positions are unified in the notion of ‘absolute present’, which was put forward in the philosophy of Nishida Kitarō (1871–1945). In addition, we argue that it is in this notion of absolute present that the views of Schrödinger, Dōgen and Nishida meet

Regional and monthly and clear-sky aerosol direct radiative effect (and forcing) derived from the GlobAEROSOL-AATSR satellite aerosol product

Using the GlobAEROSOL-AATSR dataset, estimates of the instantaneous, clear-sky, direct aerosol radiative effect and radiative forcing have been produced for the year 2006. Aerosol Robotic Network sun-photometer measurements have been used to characterise the random and systematic error in the GlobAEROSOL product for 22 regions covering the globe. Representative aerosol properties for each region were derived from the results of a wide range of literature sources and, along with the de-biased GlobAEROSOL AODs, were used to drive an offline version of the Met Office unified model radiation scheme. In addition to the mean AOD, best-estimate run of the radiation scheme, a range of additional calculations were done to propagate uncertainty estimates in the AOD, optical properties, surface albedo and errors due to the temporal and spatial averaging of the AOD fields. This analysis produced monthly, regional estimates of the clear-sky aerosol radiative effect and its uncertainty, which were combined to produce annual, global mean values of (−6.7±3.9)Wm−2 at the top of atmosphere (TOA) and (−12±6)Wm−2 at the surface. These results were then used to give estimates of regional, clear-sky aerosol direct radiative forcing, using modelled pre-industrial AOD fields for the year 1750 calculated for the AEROCOM PRE experiment. However, as it was not possible to quantify the uncertainty in the pre-industrial aerosol loading, these figures can only be taken as indicative and their uncertainties as lower bounds on the likely errors. Although the uncertainty on aerosol radiative effect presented here is considerably larger than most previous estimates, the explicit inclusion of the major sources of error in the calculations suggest that they are closer to the true constraint on this figure from similar methodologies, and point to the need for more, improved estimates of both global aerosol loading and aerosol optical properties

Cubic Twistorial String Field Theory

Witten has recently proposed a string theory in twistor space whose D-instanton contributions are conjectured to compute N=4 super-Yang-Mills scattering amplitudes. An alternative string theory in twistor space was then proposed whose open string tree amplitudes reproduce the D-instanton computations of maximal degree in Witten's model. In this paper, a cubic open string field theory action is constructed for this alternative string in twistor space, and is shown to be invariant under parity transformations which exchange MHV and googly amplitudes. Since the string field theory action is gauge-invariant and reproduces the correct cubic super-Yang-Mills interactions, it provides strong support for the conjecture that the string theory correctly computes N-point super-Yang-Mills tree amplitudes.Comment: 19+1 pages, 4+1 EPS figures, JHEP3 LaTeX; v2: minor corrections, references added; v3: the final version published in JHEP with a new footnote on the d=0 on-shell contributio

Small-Scale Fluidized Bed Bioreactor for Long-Term Dynamic Culture of 3D Cell Constructs and in vitro Testing

With the increasing interest in three-dimensional (3D) cell constructs that better represent native tissues, comes the need to also invest in devices, i.e., bioreactors, that provide a controlled dynamic environment similar to the perfusion mechanism observed in vivo. Here a laboratory-scale fluidized bed bioreactor (sFBB) was designed for hydrogel (i.e., alginate) encapsulated cells to generate a dynamic culture system that produced a homogenous milieu and host substantial biomass for long-term evolution of tissue-like structures and “per cell” performance analysis. The bioreactor design, conceptualized through scale-down empirical similarity rules, was initially validated through computational fluid dynamics analysis for the distributor capacity of homogenously dispersing the flow with an average fluid velocity of 4.596 × 10–4 m/s. Experimental tests then demonstrated a consistent fluidization of hydrogel spheres, while maintaining shape and integrity (606.9 ± 99.3 μm diameter and 0.96 shape factor). It also induced mass transfer in and out of the hydrogel at a faster rate than static conditions. Finally, the sFBB sustained culture of alginate encapsulated hepatoblastoma cells for 12 days promoting proliferation into highly viable (>97%) cell spheroids at a high final density of 27.3 ± 0.78 million cells/mL beads. This was reproducible across multiple units set up in parallel and operating simultaneously. The sFBB prototype constitutes a simple and robust tool to generate 3D cell constructs, expandable into a multi-unit setup for simultaneous observations and for future development and biological evaluation of in vitro tissue models and their responses to different agents, increasing the complexity and speed of R&D processes

Temperature triggers immune evasion by Neisseria meningitidis.

Neisseria meningitidis has multiple strategies to evade complement-mediated killing, which contribute to its ability to cause septicaemic disease and meningitis. However, the meningococcus is primarily an obligate commensal of the human nasopharynx, and it is unclear why the bacterium has evolved exquisite mechanisms to avoid host immunity. Here we demonstrate that mechanisms of meningococcal immune evasion and resistance against complement increase in response to an elevation in ambient temperature. We have identified three independent RNA thermosensors located in the 5′-UTRs of genes necessary for capsule biosynthesis, the expression of factor H binding protein, and sialylation of lipopolysaccharide, which are essential for meningococcal resistance against immune killing(1,2). Therefore increased temperature (which occurs during inflammation) acts as a ‘danger signal’ for the meningococcus which enhances defence against human immune killing. Infection with viral pathogens, such as influenza, leads to inflammation in the nasopharynx with an elevated temperature and recruitment of immune effectors(3,4). Thermoregulation of immune defence could offer an adaptive advantage to the meningococcus during co-infection with other pathogens, and promote the emergence of virulence in an otherwise commensal bacterium

M-theory and automorphic scattering

The strongly coupled limit of string scattering and the automorphic construction of the graviton S-matrix is compared with the eleven dimensional formulation of M-theory. In a particular scaling limit at strong string coupling, M-theory is described by eleven-dimensional supergravity which does not possess a dilaton, but rather a perturbative expansion in the gravitational coupling and derivatives. The latter theory provides an off-shell description of the string, upon dimensional reduction.Comment: 12 pages, LaTeX; v2 refs added, typos corr; v3 added comments for ref/publicatio

A Calibrated Olfactory Display for High Fidelity Virtual Environments

Olfactory displays provide a means to reproduce olfactory stimuli for use in virtual environments. Many of the designs produced by researchers, strive to provide stimuli quickly to users and focus on improving usability and portability, yet concentrate less on providing high levels of accuracy to improve the fidelity of odour delivery. This paper provides the guidance to build a reproducible and low cost olfactory display which is able to provide odours to users in a virtual environment at accurate concentration levels that are typical in everyday interactions; this includes ranges of concentration below parts per million and into parts per billion. This paper investigates build concerns of the olfactometer and its proper calibration in order to ensure concentration accuracy of the device. An analysis is provided on the recovery rates of a specific compound after excitation. This analysis provides insight into how this result can be generalisable to the recovery rates of any volatile organic compound, given knowledge of the specific vapour pressure of the compound