Is predictive coding falsifiable? Bowman, H.; Collins, D.J.; Nayak, A.K. ...
Neuroscience and biobehavioral reviews,
November 2023, 2023-11-00, 20231101, Letnik:
154
Journal Article
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Predictive-coding has justifiably become a highly influential theory in Neuroscience. However, the possibility of its unfalsifiability has been raised. We argue that if predictive-coding were ...unfalsifiable, it would be a problem, but there are patterns of behavioural and neuroimaging data that would stand against predictive-coding. Contra (vanilla) predictive patterns are those in which the more expected stimulus generates the largest evoked-response. However, basic formulations of predictive-coding mandate that an expected stimulus should generate little, if any, prediction error and thus little, if any, evoked-response. It has, though, been argued that contra (vanilla) predictive patterns can be obtained if precision is higher for expected stimuli. Certainly, using precision, one can increase the amplitude of an evoked-response, turning a predictive into a contra (vanilla) predictive pattern. We demonstrate that, while this is true, it does not present an absolute barrier to falsification. This is because increasing precision also reduces latency and increases the frequency of the response. These properties can be used to determine whether precision-weighting in predictive-coding justifiably explains a contra (vanilla) predictive pattern, ensuring that predictive-coding is falsifiable.
•Assess falsifiability of predictive coding.•Review predictive coding and present a canonical model of it.•Identify data patterns that stand against predictive coding.•Outline competing theories to predictive coding.
This article explores patterns in membership associations’ portfolios. It compares and contrasts portfolio theory, which predicts variety in revenue portfolios, with a newer benefits theory, which ...postulates that revenue options are constrained by the balance between the member benefits and societal benefits they produce. The research makes use of a new database that more accurately measures dues and program service revenue of associations than other databases. The weight of the evidence supports benefits theory more strongly than revenue portfolio theory. This research incidentally finds that revenue concentration increases with size and decreases with real estate ownership. The article introduces the concepts of one-off entry and exit costs on members (tariffs), which tend to reduce members’ sensitivity to the level of dues. Indeed, dues are often dominant among the associations having presumptively high tariffs, such as trade unions and certain recreational clubs.
Thermal rectification in defect-engineered graphene with asymmetric hole arrangements is assessed via molecular dynamics simulations. Asymmetry in two different configurations (triangular and ...rectangular hole arrangements) is controlled by manipulating geometrical parameters, such as hole size; effects of geometry on the resultant rectification are investigated. Filtering of phonon propagation directions by geometrical confinement, and asymmetric relaxation distance induce a difference in heat transfer depending on transport direction, or thermal rectification. Increase in porosity, which results in additional confinement and larger difference in relaxation, produces more significant thermal rectification. While a rectangular arrangement of holes results in 70% of the maximum thermal rectification, up to 78% of rectification was achieved using a triangular arrangement within 47.5 nm of graphene, which can be attributed to more effective phonon-hole boundary scattering with a triangular arrangement. This study suggests a feasible approach to create thermal rectification and enables its fine control, contributing to the development of phononic devices and enhancement of thermal system design for electronics.
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Quantitative shape analysis of juvenile pyroclasts is applied in volcanology to reconstruct the dynamics and styles of eruptions, and to explore the details of tephra transport, dispersal, and ...emplacement. Morphometric analyses often include comparison of multiple data sets with a set of dimensionless shape parameters. Here we present "DendroScan", an open source Matlab program that provides the user with all the multivariate statistical methods needed to produce such morphometric comparisons. Serving as a statistical "toolbox", DendroScan conducts Levene-, t-, and equivalence tests, presenting the results in ad hoc interpretable graphs. Furthermore, it is designed to conduct dendrogrammatic analyses of particle morphometry, a recently developed approach for the inter-comparison of multiple morphometric data sets. DendroScan produces tree diagrams, in which the analysed samples are sorted according to their morphometric dissimilarity, allowing the user to identify, e.g., samples that are statistically equivalent. To demonstrate DendroScan's potential, ten experimental samples are compared with volcanic ash samples generated by the Havre 2012 deep-sea eruption in the Kermadec arc (New Zealand). We show how, using DendroScan-based results, information on the eruptive mechanism can be inferred, and how the cooling history of the experimental melt is reflected in the dissimilarity of thermally granulated fragments.
In the present work, an analytical method has been developed for the determination of the amount of man-made beryllium metal and/or beryllium compounds in soil in addition to the amount of native ...beryllium that is present. The method is based on the premise that if high-fired beryllium oxide can be extracted efficiently, then beryllium metal and acid-soluble beryllium salts would also be extracted efficiently.
The proposed method involves the addition of 9 mL of an aqueous solution of 5% (wt/vol) ammonium bifluoride (ABF) to a 10-mL tube with 250 mg of dried, sieved soil. The tube is placed in a convection oven at 70 ᵒC and is mechanically rocked for 60 min to mix the sample while it is being heated. Beryllium oxide, beryllium metal and beryllium salts would include virtually all of the anthropogenic (man-made) beryllium compounds that might contaminate soil. Compounds that may be naturally present in soil, such as beryllium silicates and beryllium aluminosilicates, are not extracted efficiently by ABF solution under these conditions. As a second step after the initial extraction of the sample of soil with ABF solution, the soil is completely dissolved in a mixture of strong acids and that acid solution is then analyzed to determine the residual beryllium.
The ratio of the extractable to residual beryllium in the same aliquot of native soil can be measured for a soil type in a local region and then used to calculate the amount of anthropogenic beryllium in soil. Therefore, the method may have application in the measurement of beryllium-contaminated soil at sites where beryllium oxide, beryllium metal and/or beryllium salts may have been used.
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•Beryllium was partially extracted from soil with ammonium-bifluoride solution.•Soils samples with solution were rocked while they were heated in an oven.•R is the ratio of extracted beryllium to residual beryllium in native soil.•Anthropogenic beryllium is calculated with R from extracted and residual beryllium.
To address the role of small regulatory RNAs in rice development, we generated a large data set of small RNAs from mature leaves and developing roots, shoots, and inflorescences. Using a spatial ...clustering algorithm, we identified 36,780 genomic groups of small RNAs. Most consisted of 24-nt RNAs that are expressed in all four tissues and enriched in repeat regions of the genome; 1029 clusters were composed primarily of 21-nt small RNAs and, strikingly, 831 of these contained phased RNAs and were preferentially expressed in developing inflorescences. Thirty-eight of the 24-mer clusters were also phased and preferentially expressed in inflorescences. The phased 21-mer clusters derive from nonprotein coding, nonrepeat regions of the genome and are grouped together into superclusters containing 10-46 clusters. The majority of these 21-mer clusters (705/831) are flanked by a degenerate 22-nt motif that is offset by 12 nt from the main phase of the cluster. Small RNAs complementary to these flanking 22-nt motifs define a new miRNA family, which is conserved in maize and expressed in developing reproductive tissues in both plants. These results suggest that the biogenesis of phased inflorescence RNAs resembles that of tasiRNAs and raise the possibility that these novel small RNAs function in early reproductive development in rice and other monocots.
Dicer-like (DCL) enzymes play a pivotal role in RNA silencing in plants, processing the long double-stranded RNA (dsRNA) that triggers silencing into the primary short interfering RNAs (siRNAs) that ...mediate it. The siRNA population can be augmented and silencing amplified via transitivity, an RNA-dependent RNA polymerase (RDR)-dependent pathway that uses the target RNA as substrate to generate secondary siRNAs. Here we report that Arabidopsis DCL2-but not DCL4-is required for transitivity in cell-autonomous, post-transcriptional silencing of transgenes. An insertion mutation in DCL2 blocked sense transgene-induced silencing and eliminated accumulation of the associated RDR-dependent siRNAs. In hairpin transgene-induced silencing, the dcl2 mutation likewise eliminated accumulation of secondary siRNAs and blocked transitive silencing, but did not block silencing mediated by primary siRNAs. Strikingly, in all cases, the dcl2 mutation eliminated accumulation of all secondary siRNAs, including those generated by other DCL enzymes. In contrast, mutations in DCL4 promoted a dramatic shift to transitive silencing in the case of the hairpin transgene and enhanced silencing induced by the sense transgene. Suppression of hairpin and sense transgene silencing by the P1/HC-Pro and P38 viral suppressors was associated with elimination of secondary siRNA accumulation, but the suppressors did not block processing of the stem of the hairpin transcript into primary siRNAs. Thus, these viral suppressors resemble the dcl2 mutation in their effects on siRNA biogenesis. We conclude that DCL2 plays an essential, as opposed to redundant, role in transitive silencing of transgenes and may play a more important role in silencing of viruses than currently thought.
Open Source Intelligence (OSINT): An Oxymoron? Miller, Bowman H.
International journal of intelligence and counterintelligence,
10/2018, Letnik:
31, Številka:
4
Journal Article, Book Review
Recenzirano
In today's world information of all kinds is available to anyone who cares to see it. Here, Miller discuss whether Open Source Intelligence is an oxymoron.
RNA silencing is a highly conserved pathway in the network of interconnected defense responses that are activated during viral infection. As a counter-defense, many plant viruses encode proteins that ...block silencing, often also interfering with endogenous small RNA pathways. However, the mechanism of action of viral suppressors is not well understood and the role of host factors in the process is just beginning to emerge. Here we report that the ethylene-inducible transcription factor RAV2 is required for suppression of RNA silencing by two unrelated plant viral proteins, potyvirus HC-Pro and carmovirus P38. Using a hairpin transgene silencing system, we find that both viral suppressors require RAV2 to block the activity of primary siRNAs, whereas suppression of transitive silencing is RAV2-independent. RAV2 is also required for many HC-Pro-mediated morphological anomalies in transgenic plants, but not for the associated defects in the microRNA pathway. Whole genome tiling microarray experiments demonstrate that expression of genes known to be required for silencing is unchanged in HC-Pro plants, whereas a striking number of genes involved in other biotic and abiotic stress responses are induced, many in a RAV2-dependent manner. Among the genes that require RAV2 for induction by HC-Pro are FRY1 and CML38, genes implicated as endogenous suppressors of silencing. These findings raise the intriguing possibility that HC-Pro-suppression of silencing is not caused by decreased expression of genes that are required for silencing, but instead, by induction of stress and defense responses, some components of which interfere with antiviral silencing. Furthermore, the observation that two unrelated viral suppressors require the activity of the same factor to block silencing suggests that RAV2 represents a control point that can be readily subverted by viruses to block antiviral silencing.
How does the brain combine information predictive of the value of a visually guided task (incentive value) with information predictive of where task-relevant stimuli may occur (spatial certainty)? ...Human behavioural evidence indicates that these two predictions may be combined additively to bias visual selection (
Additive Hypothesis
), whereas neuroeconomic studies posit that they may be multiplicatively combined (
Expected Value Hypothesis
). We sought to adjudicate between these two alternatives. Participants viewed two coloured placeholders that specified the potential value of correctly identifying an imminent letter target if it appeared in that placeholder. Then, prior to the target’s presentation, an endogenous spatial cue was presented indicating the target’s more likely location. Spatial cues were parametrically manipulated with regard to the information gained (in bits). Across two experiments, performance was better for targets appearing in high versus low value placeholders and better when targets appeared in validly cued locations. Interestingly, as shown with a Bayesian model selection approach, these effects did not interact, clearly supporting the Additive Hypothesis. Even when conditions were adjusted to increase the optimality of a multiplicative operation, support for it remained. These findings refute recent theories that expected value computations are the singular mechanism driving the deployment of endogenous spatial attention. Instead, incentive value and spatial certainty seem to act independently to influence visual selection.
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