4,768 research outputs found
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
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
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
SYSTEMS-2: a randomised phase II study of radiotherapy dose escalation for pain control in malignant pleural mesothelioma
SYSTEMS-2 is a randomised study of radiotherapy dose escalation for pain control in 112 patients with malignant pleural mesothelioma (MPM). Standard palliative (20Gy/5#) or dose escalated treatment (36Gy/6#) will be delivered using advanced radiotherapy techniques and pain responses will be compared at week 5. Data will guide optimal palliative radiotherapy in MPM
Absolute Present, Zen and Schrödingerâs 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 Schrödingerâs view on One Mind with the teachings of DĆgen, 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 âabsolute presentâ, which was put forward in the philosophy of Nishida KitarĆ (1871â1945). In addition, we argue that it is in this notion of absolute present that the views of Schrödinger, DĆgen and Nishida meet
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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 (â6.7±3.9)Wmâ2 at the top of atmosphere (TOA) and (â12±6)Wmâ2 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
Bronchiectasis insanity:Doing the same thing over and over again and expecting different results?
Bronchiectasis is an increasingly common disease with a significant impact on quality of life and morbidity of affected patients. It is also a very heterogeneous disease with numerous different underlying etiologies and presentations. Most treatments for bronchiectasis are based on low-quality evidence; consequently, no treatments have been approved by the US Food and Drug Administration or the European Medicines Agency for the treatment of bronchiectasis. The last several years have seen numerous clinical trials in which the investigational agent, thought to hold great promise, did not demonstrate a clinically or statistically significant benefit. This commentary will review the likely reasons for these disappointing results and a potential approach that may have a greater likelihood of defining evidence-based treatment for bronchiectasis
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 âper cellâ 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 Ă 10â4 m/s. Experimental tests then demonstrated a consistent fluidization of hydrogel spheres, while maintaining shape and integrity (606.9 ± 99.3 ÎŒm 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
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