5,038 research outputs found
Grounding the Unreal
The scientific successes of the last 400 years strongly suggest a picture on which our scientific theories exhibit a layered structure of dependence and determination. Economics is dependent on and determined by psychology; psychology in its turn is, plausibly, dependent on and determined by biology; and so it goes. It is tempting to explain this layered structure of dependence and determination among our theories by appeal to a corresponding layered structure of dependence and determination among the entities putatively treated by those theories. In this paper, I argue that we can resist this temptation: we can explain the sense in which, e.g., the biological truths are dependent on and determined by chemical truths without appealing to properly biological or chemical entities. This opens the door to a view on which, though there are more truths than just the purely physical truths, there are no entities, states, or properties other than the purely physical entities, states, and properties. I argue that some familiar strategies to explicate the idea of a layered structure of theories by appeal to reduction, ground, and truthmaking encounter difficulties. I then show how these difficulties point the way to a more satisfactory treatment which appeals to something very close to the notion of ground. Finally, I show how this treatment provides a theoretical setting in which we might fruitfully frame debates about which entities there really are
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AAVR-Displaying Interfaces: Serotype-Independent Adeno-Associated Virus Capture and Local Delivery Systems.
Interfacing gene delivery vehicles with biomaterials has the potential to play a key role in diversifying gene transfer capabilities, including localized, patterned, and controlled delivery. However, strategies for modifying biomaterials to interact with delivery vectors must be redesigned whenever new delivery vehicles and applications are explored. We have developed a vector-independent biomaterial platform capable of interacting with various adeno-associated viral (AAV) serotypes. A water-soluble, cysteine-tagged, recombinant protein version of the recently discovered multi-AAV serotype receptor (AAVR), referred to as cys-AAVR, was conjugated to maleimide-displaying polycaprolactone (PCL) materials using click chemistry. The resulting cys-AAVR-PCL system bound to a broad range of therapeutically relevant AAV serotypes, thereby providing a platform capable of modulating the delivery of all AAV serotypes. Intramuscular injection of cys-AAVR-PCL microspheres with bound AAV vectors resulted in localized and sustained gene delivery as well as reduced spread to off-target organs compared to a vector solution. This cys-AAVR-PCL system is thus an effective approach for biomaterial-based AAV gene delivery for a broad range of therapeutic applications
Boring Infinite Descent
WOS: 000333647500012In formal ontology, infinite regresses are generally considered a bad sign. One debate where such regresses come into play is the debate about fundamentality. Arguments in favour of some type of fundamentalism are many, but they generally share the idea that infinite chains of ontological dependence must be ruled out. Some motivations for this view are assessed in this article, with the conclusion that such infinite chains may not always be vicious. Indeed, there may even be room for a type of fundamentalism combined with infinite descent as long as this descent is “boring,” that is, the same structure repeats ad infinitum. A start is made in the article towards a systematic account of this type of infinite descent. The philosophical prospects and scientific tenability of the account are briefly evaluated using an example from physics.Peer reviewe
Quantum Phase Transition in Heisenberg-Kitaev Model
We explore the nature of the quantum phase transition between a magnetically
ordered state with collinear spin pattern and a gapless spin liquid in
the Heisenberg-Kitaev model. We construct a slave particle mean field theory
for the Heisenberg-Kitaev model in terms of complex fermionic spinons. It is
shown that this theory, formulated in the appropriate basis, is capable of
describing the Kitaev spin liquid as well as the transition between the gapless
spin liquid and the so-called stripy antiferromagnet. In particular,
within a mean field theory, we have a discontinuous transition from the
spin liquid to the stripy antiferromagnet. We argue, however, that subtle
spinon confinement effects, associated with the instability of gapped U(1) spin
liquid in two spatial dimensions, are playing an important role at the
transition. The possibility of an exotic continuous transition is briefly
addressed.Comment: 12 pages, 6 figure
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POWER: Parallel Optimizations With Executable Rewriting
The hardware industry's rapid development of multicore and many core hardware has outpaced the software industry's transition from sequential to parallel programs. Most applications are still sequential, and many cores on parallel machines remain unused. We propose a tool that uses data-dependence profiling and binary rewriting to parallelize executables without access to source code. Our technique uses Bernstein's conditions to identify independent sets of basic blocks that can be executed in parallel, introducing a level of granularity between fine-grained instruction level and coarse grained task level parallelism. We analyze dynamically generated control and data dependence graphs to find independent sets of basic blocks which can be parallelized. We then propose to parallelize these candidates using binary rewriting techniques. Our technique aims to demonstrate the parallelism that remains in serial application by exposing concrete opportunities for parallelism
Number of Replications Required in Monte Carlo Simulation Studies: A Synthesis of Four Studies
Monte Carlo simulations are used extensively to study the performance of statistical tests and control charts. Researchers have used various numbers of replications, but rarely provide justification for their choice. Currently, no empirically-based recommendations regarding the required number of replications exist. Twenty-two studies were re-analyzed to determine empirically-based recommendations
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