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Apparent statistical inference in crows may reflect simple reinforcement learning
Get PDFJohnston et al. report results which they argue demonstrate that crows engage in statistical inference during decision-making. They trained two crows to associate a set of stimuli with different reward probabilities (from 10% to 90%) before choice tests between pairs of stimuli. Across most pairwise combinations, and in a control task in which the number of rewards was equated between probabilities, both crows preferred the stimulus associated with higher reward probability. The magnitude of this preference was affected by the absolute difference between the two probabilities, although (contrary to a claim made by Johnston et al. 2023) preference did not reflect the ratio of prior probabilities independently of absolute differences. Johnston et al. argue that preference for the stimulus with the higher reward probability is “the signature of true statistical inference” (p. 3238), implemented by an analogue magnitude system that represents the reward probability associated with each stimulus. Here, we show that a simple reinforcement learning model, with no explicit representation of reward probabilities, reproduces the critical features of crows’ performance—and indeed better accounts for the observed empirical findings than the concept of statistical inference based on analogue magnitude representations, because it correctly predicts the absence of a ratio effect that would reflect magnitudes when absolute distance is controlled. Contrary to Johnston et al.’s claims, these patterns of behaviour do not necessitate retrieval of calculated reward probabilities from long-term memory and dynamic application of this information across contexts, or (more specifically) require the involvement of an analogue magnitude system in representing abstract probabilities
Experimental assessment of the performance of terrestrial laser scanners in monitoring the geometric deformations in retaining walls
Get PDFThe Terrestrial Laser Scanner (TLS) has a great potential to be used in monitoring structures, specifically retaining walls, due to its fast acquisition and contactless function. However, previous research showed that the accuracy of deformation estimation using the TLS varied between few millimeters to a few centimeters. The Structural Health Monitoring (SHM) of retaining walls is executed according to their serviceability limits, and has to be taken with a tolerance of a few millimeters. Therefore, the aim in this study is to propose methods and approaches that ensure that the accuracy of the deformation estimation using the TLS is within 1-2mm. This study is based on experimental assessment, where the main scenarios of geometric deformations in retaining walls are simulated through an experimental device (i.e., wooden sheet). The wooden sheet was scanned by a TLS from distance varying from 10-27m with scanning angle varying between 0∘and20∘. The wooden sheet was designed to simulate three main scenarios of deformation (i.e., lateral displacement, settlement and tilt) with amplitudes varying from 2to16mm and 0.2∘to1.6∘ for tilt. This study presents a holistic attempt based on controlled experiments to evaluate the performance in monitoring deformation, using a multi-parametric analysis and identifying approaches to enhance the application of TLS in monitoring deformation of wall-type structures, such as retaining wall. The TLS measurements were compared to robotic total station measurements as well as absolute measurements using a ruler. These strategies should enhance the efficient use of the TLS in monitoring small geometric deformations
The effects of maternal flow on placental diffusion‐weighted MRI and intravoxel incoherent motion parameters
Get PDFPurposeTo investigate and explain observed features of the placental DWI signal in healthy and compromised pregnancies using a mathematical model of maternal blood flow.MethodsThirteen healthy and nine compromised third trimester pregnancies underwent pulse gradient spin echo DWI MRI, with the results compared to MRI data simulated from a 2D mathematical model of maternal blood flow through the placenta. Both sets of data were fitted to an intravoxel incoherent motion (IVIM) model, and a rebound model (defined within text), which described voxels that did not decay monotonically. Both the in vivo and simulated placentas were split into regions of interest (ROIs) to analyze how the signal varies and how IVIM and rebounding parameters change across the placental width.ResultsThere was good agreement between the in vivo MRI data, and the data simulated from the mathematical model. Both sets of data included voxels showing a rebounding signal and voxels showing fast signal decay focused near the maternal side of the placenta. In vivo we found higher fIVIM in the uterine wall and near the maternal side of the placenta, with the slow diffusion coefficient D reduced in all ROIs in compromised pregnancy.ConclusionA simulation based entirely on maternal blood explains key features observed in placental DWI, indicating the importance of maternal blood flow in interpreting placental MRI data, and providing potential new metrics for understanding changes in compromised placentas
Anxiety-Symptom Severity and Implicit and Explicit Self-as-Anxious Associations in a Large Online Sample of U.S. Adults: Trends From 2011 to 2022
Get PDFSome studies have suggested a rise in anxiety prevalence and severity over the past decade, particularly among emerging adults, whereas others have reported stable rates. In this preregistered study, we examine trends in anxiety-symptom severity and explicit (self-reported) and implicit (using the Brief Implicit Association Test) associations about the self as anxious versus calm. Using continuous cross-sectional data from 99,973 U.S. adults who visited the Project Implicit Health website between 2011 and 2022, we compared trends in anxiety outcomes between emerging adults (ages 18–25) and adults ages 26+, including during the COVID-19 pandemic. Contrary to hypotheses, average anxiety severity and strength of implicit/explicit self-as-anxious associations did not spike at the start of the pandemic, and rates of change did not significantly differ by age from 2011 to 2020 except for explicit, nonrelative self-as-anxious ratings. Instead, anxiety mostly remained stable; emerging adults exhibited consistently higher anxiety-symptom severity and stronger implicit/explicit self-as-anxious associations than adults ages 26+
Geometric Calibration of Thermal Infrared Cameras: A Comparative Analysis for Photogrammetric Data Fusion
Get PDFFeasibility of diffuse Raman spectroscopy to detect in-vivo molecular changes in the tissue induced by subcutaneous implants
Get PDFBiomaterials are being designed for a broad range of medical applications, but regardless of their endpoint use, they trigger host immune responses, also known as foreign body responses (FBR). This study investigates the feasibility of using diffuse Raman spectroscopy (DRS) to detect in-vivo molecular changes in subcutaneous tissue situated immediately below the dermis. A mouse model of FBR after subcutaneous implantation of woven polyethylene terephthalate fibres is used to investigate this approach. Numerical modelling of light propagation in tissue is used to optimise the DRS instrument to detect Raman signals related to FBR-induced collagen deposition in tissue surrounding the PET fibres. Post-mortem in-situ measurements on mice (day 14, 21 and 28 post-implantation) showed that the intensity of the 930 cm-1 Raman band, corresponds to collagen, correlating with the level of FBR observed by histology. The optimised DRS instrument allows the acquisition of in-vivo spectra from on mice under anaesthesia (day 7 and 28 post-implantation). Spectra from live mice (in-vivo) show a similar correlation between the intensity of the 930 cm-1 collagen Raman band with the level of FBR, in agreement with the histology assessment of the skin. These results demonstrate the feasibility of performing in-vivo DRS measurements on a mouse model to detect molecular changes caused by FBR in the subcutaneous region below the skin. Such measurements can help the design of new biomaterials since it would enable longitudinal measurements of FBR on an individual animal rather the sacrificing animals for histology at specific time endpoints. Furthermore, it is amenable to development for monitoring FBR of implants clinically
Localized growth factor delivery from microparticles modulates osteogenic and chondrogenic gene expression in a growth factor-dependent manner in an ex vivo chick embryonic bone model
Get PDFGrowth factors play a crucial role in regulating various cellular functions, including proliferation and differentiation. Consequently, the biomaterial-based delivery of exogenous growth factors presents a promising strategy in regenerative medicine to manage the healing process and restore tissue function. For effective therapeutic applications, it is essential that these active compounds are precisely targeted to the site of regeneration, with release kinetics that align with the gradual pace of tissue growth. We have developed an ex vivo model utilizing a developing embryonic chick bone, and using PLGA-based microparticles as controlled-release systems, allowing for the investigation of the spatiotemporal effects of growth factor delivery on cell differentiation and tissue formation. Our findings demonstrate that BMP2 and FGF2 can significantly alter cell morphology and zonally pattern collagen deposition within the model, but only when the growth factor presentation rate is carefully regulated. Furthermore, the growth factor-dependent responses observed underscore the potential of this model to explore interactions between cells and the growth factors released from biomaterials in an approach which can be applied to bone tissue engineering
Recyclable Multifunctional Ionic Liquids for Sustainable Electroorganic Oxidations
Get PDFThe study of electrochemical oxidations has wide-ranging implications, from the development of new electrocatalysts for fuel cells for energy conversion, to the synthesis of fine chemicals. 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO) has been used for decades as a sustainable, metal-free mediator for chemical oxidations and is now being used for electrochemical oxidations. We describe here a novel approach to TEMPO-mediated electrooxidations, in which the chemical input and waste generated during electrooxidations of alcohols are minimized by using a multifunctional room temperature ionic liquid (RTIL) to facilitate flow electrosynthesis. Our three-pronged approach involves the following: (1) the use of a recyclable alkylimidazolium-based RTIL to replace the electrolytes and volatile organic solvents typically used in TEMPO-mediated alcohol electrooxidations; (2) pairing alcohol oxidation at the positive electrode with electroreduction of the cationic component of the RTIL at the negative electrode to generate the base required for the electrosynthesis; (3) incorporation of the catalytic TEMPO moiety in our RTIL-based system. We demonstrate the possibilities offered by our strategy using a range of alcohols, illustrating the scope of reactions that can be driven using our strategy and demonstrating the opportunities offered by task-specific, multifunctional RTILs for electroorganic synthesis
Insulin-like peptide 3 is not a biomarker for pancreatic ductal adenocarcinoma
Get PDFPancreatic ductal carcinoma (PDAC) is a rapidly growing cancer with a very poor prognosis. It is, therefore, important to develop novel, specific biomarkers to identify such cancers as early as possible. In a recent article published in Nature Cell Biology, Yeom and colleagues postulated that circulating insulin-like peptide 3 (INSL3) might serve as such a biomarker. Experiments were first conducted in Drosophila to show that the Dilp8/Lgr3 system regulated the fly equivalent of cachexia. This was then translated to humans to imply the involvement of the INSL3/RXFP2 system in PDAC-associated cachexia and that circulating INSL3 might serve as an early PDAC biomarker. We have now analyzed blood and tumor tissue from PDAC patients using a well-validated and recognized INSL3 immunoassay and specific antihuman INSL3 antibodies, and find no evidence to support these claims. We consider that this is largely due to Yeom and colleagues using a poorly validated immunoassay and antibodies for INSL3. Unfortunately, therefore, this peptide is not suitable for consideration as a PDAC biomarker
Cornelius Castoriadis and Marxism
Get PDFIn this paper I examine what Cornelius Castoriadis (1922–1997) has to say about Marx and Marxism. Castoriadis was throughout the post-War period, for three decades, a Marxist, albeit of an unorthodox or heterodox kind. However, after 1968, he claimed to have broken completely with Marxism and to have developed an alternative theoretical approach of his own, associated with his Autonomy Project. In this later period he argues that Marx's ideas have become irrelevant and have no contribution to make to addressing the problems of today. My article engages critically with that view. I argue not only that a number of Marx's ideas continue to be relevant today, but also that the views of the later Castoriadis himself rely heavily on them. Ultimately, therefore Castoriadis's attempt to break completely with Marxism is unsuccessful
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