3,804 research outputs found

    Working with Constrained Systems: A Review of A. K. Joshi's IJCAI-97 Research Excellence Award Acceptance Lecture

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    This is a brief review of Joshi's award acceptance lecture published in <I>AI Magazine</I>. This review appeared in the AI Watch column in <I>Computers and Society</I>, a quarterly magazine

    Partially Resolving the Tension between Omniscience and Free Will: A Mathematical Argument

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    We put forward a probability-based theory of temptation with implications for philosophy of religion and philosophy of mind, alike

    Can One Really Reason about Laws?

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    Precedent decides legal cases, but few precedents make the case at bar <I>res judicata</I>. Instead, analogical reasoning is used, together with canons of statutory interpretation and theories of constitutional jurisprudence. The work under review provides a model and algorithm for analogical reasoning in the legal context. Technically, the paper represents very fine work, except that in order to find the ground of a rule, some human input is required. The rule is denied and consequences of the negation are automatically derived; then, those which a person has previously marked as undesirable are candidates for the rule's ground. So this is a man-machine system, something not emphasized by the authors. Still, it is very fine work. Aside from its technical excellence and, on the other hand, an annoying number of missing articles, misplaced modifiers, and failures of agreement, the authors imply a certain understanding of law and how laws are made. The paper uses an ordinance rather than cases for analogical reasoning, after all, a practice that makes little sense unless the legislature is always perfectly consistent. Hence, the whole epistemological basis for the paper may be flawed

    "The Extended Mind"--Extended

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    We review the argument made by Clark and Chalmers in <I>Analysis</I> for a limited externalism and extend their argument from declarative knowledge to procedural knowledge

    Transcriptomic signatures of neuronal differentiation and their association with risk genes for autism spectrum and related neuropsychiatric disorders.

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    Genes for autism spectrum disorders (ASDs) are also implicated in fragile X syndrome (FXS), intellectual disabilities (ID) or schizophrenia (SCZ), and converge on neuronal function and differentiation. The SH-SY5Y neuroblastoma cell line, the most widely used system to study neurodevelopment, is currently discussed for its applicability to model cortical development. We implemented an optimal neuronal differentiation protocol of this system and evaluated neurodevelopment at the transcriptomic level using the CoNTeXT framework, a machine-learning algorithm based on human post-mortem brain data estimating developmental stage and regional identity of transcriptomic signatures. Our improved model in contrast to currently used SH-SY5Y models does capture early neurodevelopmental processes with high fidelity. We applied regression modelling, dynamic time warping analysis, parallel independent component analysis and weighted gene co-expression network analysis to identify activated gene sets and networks. Finally, we tested and compared these sets for enrichment of risk genes for neuropsychiatric disorders. We confirm a significant overlap of genes implicated in ASD with FXS, ID and SCZ. However, counterintuitive to this observation, we report that risk genes affect pathways specific for each disorder during early neurodevelopment. Genes implicated in ASD, ID, FXS and SCZ were enriched among the positive regulators, but only ID-implicated genes were also negative regulators of neuronal differentiation. ASD and ID genes were involved in dendritic branching modules, but only ASD risk genes were implicated in histone modification or axonal guidance. Only ID genes were over-represented among cell cycle modules. We conclude that the underlying signatures are disorder-specific and that the shared genetic architecture results in overlaps across disorders such as ID in ASD. Thus, adding developmental network context to genetic analyses will aid differentiating the pathophysiology of neuropsychiatric disorders

    Review of the Laguerre-Gauss mode technology research program at Birmingham

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    Gravitational wave detectors from the advanced generation onwards are expected to be limited in sensitivity by thermal noise of the optics, making the reduction of this noise a key factor in the success of such detectors. A proposed method for reducing the impact of this noise is to use higher-order Laguerre-Gauss (LG) modes for the readout beam, as opposed to the currently used fundamental mode. We present here a synopsis of the research program undertaken by the University of Birmingham into the suitability of LG mode technology for future gravitational wave detectors. This will cover our previous and current work on this topic, from initial simulations and table-top LG mode experiments up to implementation in a prototype scale suspended cavity and high-power laser bench

    Experimental test of higher-order Laguerre–Gauss modes in the 10 m Glasgow prototype interferometer

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    Brownian noise of dielectric mirror coatings is expected to be one of the limiting noise sources, at the peak sensitivity, of next generation ground based interferometric gravitational wave (GW) detectors. The use of higher-order Laguerre–Gauss (LG) beams has been suggested to reduce the effect of coating thermal noise in future generations of gravitational wave detectors. In this paper we describe the first test of interferometry with higher-order LG beams in an environment similar to a full-scale gravitational wave detector. We compare the interferometric performance of higher-order LG modes and the fundamental mode beams, injected into a 10 m long suspended cavity that features a finesse of 612, a value chosen to be typical of future gravitational wave detectors. We found that the expected mode degeneracy of the injected LG3, 3 beam was resolved into a multiple peak structure, and that the cavity length control signal featured several nearby zero crossings. The break up of the mode degeneracy is due to an astigmatism (defined as |Rcy − Rcx|) of 5.25 ± 0.5 cm on one of our cavity mirrors with a radius of curvature (Rc) of 15 m. This observation agrees well with numerical simulations developed with the FINESSE software. We also report on how these higher-order mode beams respond to the misalignment and mode mismatch present in our 10 m cavity. In general we found the LG3, 3 beam to be considerably more susceptible to astigmatism and mode mismatch than a conventional fundamental mode beam. Therefore the potential application of higher-order Laguerre–Gauss beams in future gravitational wave detectors will impose much more stringent requirements on both mode matching and mirror astigmatism

    Small optic suspensions for Advanced LIGO input optics and other precision optical experiments

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    We report on the design and performance of small optic suspensions developed to suppress seismic motion of out-of-cavity optics in the Input Optics subsystem of the Advanced LIGO interferometric gravitational wave detector. These compact single stage suspensions provide isolation in all six degrees of freedom of the optic, local sensing and actuation in three of them, and passive damping for the other three
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