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How does the similarity structure of memory influence credit assignment in reinforcement learning? Memory spaces vary in how integrated versus separable their constituent dimensions are, and how clustered versus distributed items are across dimensions. Greater integration may cause people to overattribute value to multiple dimensions, potentially leading to generalization errors. Greater clustering may bias people to attribute value to discrete category-centers (category-based learning) rather than map value continuously across the space (function learning). In this study, subjects complete a value-learning task in which stimuli are sampled from low-dimensional perceptual spaces, and reward is mapped to one dimension. Each space is intended to engender a different degree of integration and clustering in memory, such that effects of memory organization on learning can be probed. Additionally, we investigate how credit assignment on each of these artificial perceptual spaces differs to credit assignment on more complex spaces that define real-world semantic concepts.

Past work has made conflicting proposals about the mechanisms underlying instructed reinforcement learning (RL)specifically,that prefrontal cortex, representing instruction, either biases, attenuates, or overrides learning signals in the brain. Weleverage the sensitivity of pattern-similarity analysis of fMRI data to distinguish between the qualitative features of theseaccounts. Participants learn the value of six novel stimuli after receiving false information that one is of high value. Wetrack markers of value learning in visual cortex during a value-independent perceptual judgement task presented betweenintervals of RL. We predict that with learning, the correlation between activation patterns for similarly valued stimuli willincrease. To characterize influences on learning, we examine how the rate at and direction in which these patterns changein similarity will be influenced by explicit instruction about stimulus value. This work will help us identify the principlecognitive and neural mechanisms underlying instructed RL.

Energy and entropy are two of the most important concepts in science. For all natural processes where a system exchanges energy with its environment, the energy of the system tends to decrease and the entropy of the system tends to increase. Free energy is the special concept that specifies how to balance the opposing tendencies to minimize energy and maximize entropy. There are many pedagogical articles on energy and entropy. Here we present a simple model to illustrate the concept of free energy and the principle of minimum free energy.

Newton's proof of the connection between elliptical orbits and inverse-square forces ranks among the "top ten" calculations in the history of science. This time-honored calculation is a highlight in an upper-level mechanics course. It would be worthwhile if students in introductory physics could prove the relation "elliptical orbit" [arrow right] 1/r[superscript 2] "force" without having to rely on upper-level mathematics. We introduce a simple procedure--Newton's Recipe--that allows students to readily and accurately deduce the algebraic form of force laws from a geometric analysis of orbit shapes.

Introduction: The pathological decrease of fetal growth during gestation can lead to subsequent poor health outcomes for the fetus. This process is commonly controlled by the placenta, the interface between mother and baby during gestation. Sex-specific gene expression has been implicated in placental function, therefore, there is a need to determine if it is important during reduced fetal growth. We therefore aimed to characterise placental gene expression at term to evaluate sex-specific genetic changes that occur in small for gestational age (SGA) infants.Methods: RNA-sequencing of twelve human placental tissue samples collected from pregnancies yielding either term appropriate for gestational age (AGA) or SGA infants identified at delivery. Candidate genes associated with fetal size and fetal sex were identified using differential gene expression and weighted gene co-expression network analyses. Single-cell sequencing data was used for candidate validation and to estimate candidate transcript expression in specific placental cell populations.Results: Differential gene expression and weighted gene co-expression network analyses identified 403 candidate transcripts associated with SGA infants. One hundred and three of these transcripts showed sex-specific expression. . Published placental sequencing datasets were used to validate the key expression results from the twelve placental samples initially studied; the sex-independent transcript expression for genes involved in cell cycle processes in males (7 transcripts) and endoplasmic reticulum stress in females (17 transcripts).Discussion: This study identified the activation of multiple molecular mechanisms involved in the placental response to an adverse environmental stressor. Mechanisms such as disrupted protein synthesis were shared between infant biological sex when comparing AGA to SGA, whilst other pathways such as cell cycle and endoplasmic reticulum stress appear as independent/specific to either males or females when investigating reduced fetal growth. This data suggests that sexual dimorphism is an important consideration when examining placental dysfunction and poor fetal growth. [ABSTRACT FROM AUTHOR]

This study of white-collar working women investigates their views toward retirement with emphasis on variables contributing to attitudes and behavior. Findings indicate inadequate preparation for retirement and suggest areas of research related to contemporary female work patterns which may assist practitioners and policy-makers to correct the inadequacies. (Author)

The article discusses the plague that struck Sydney, New South Wales between January 19 and August 9, 1900. Topics covered include the appointment of epidemiologist Dr. J. Ashburton Thompson as chief medical officer of New South Wales in 1896, a headline by "The Sydney Morning Herald" newspaper on March 3, 1900 about the plague, and the negligence of the government and city council to enforce existing public health and housing laws and regulations.

Background: Aortic aneurysm repair is a high-risk surgical procedure. Patients are often elderly, with multiple comorbidities that predispose them to perioperative morbidity. Use of endovascular aneurysm repair (EVAR) has increased due to reduced early perioperative risk. This study assessed whether preoperative cardiopulmonary exercise testing (CPET) could be used to predict morbidity and hospital length of stay (LOS) after aortic aneurysm repair. Methods: A total of 185 patients underwent surgical repair (84 open repairs, 101 EVAR) and had adequate determination of a submaximal CPET parameter (anaerobic threshold). Results: Patient comorbidities and cardiorespiratory fitness, derived from CPET, were similar between surgical procedures. Patients undergoing EVAR had fewer complications (10% vs 32%; P < .0001) and shorter mean (standard deviation [SD]) hospital LOS of 5.7 (9.3) days vs 14.4 (10.9) days compared with open repair (P < .0001). The hospital LOS was significantly increased in patients with one or more complications in both groups compared with those with no complications. In the open repair group, the level of fitness, as defined by anaerobic threshold, was an independent predictor of postoperative morbidity and hospital LOS. When the optimal anaerobic threshold (10 mL/min/kg) derived from receiver operator curve analysis was used as a cutoff value, unfit patients stayed significantly longer than fit patients in critical care (mean, 6.4 [SD, 6.9] days vs 2.4 [SD, 2.9] days; P = .002) and in the hospital (mean, 23.1 [SD, 14.8] days vs 11.0 [SD, 6.1] days; P < .0001). In contrast, fitness in the EVAR group was not predictive of postoperative morbidity but did have predictive value for hospital LOS. Conclusions: Cardiorespiratory fitness holds significant clinical value before aortic aneurysm repair in predicting postsurgical complications and duration of critical care and hospital LOS. Preoperative measurement of fitness could then direct clinical management with regard to operative choice, postoperative resource allocation, and informed patient decision making. [Copyright &y& Elsevier]

The article discusses Scottish and British national identities and examines how these ideas played a role in the emigration of Scots and Brits to Australasia between 1875 and 1920. It explores the antipodean aspects of Scottish identity due to the struggles over loyalty to both Great Britain and Scotland and discusses how Irish minorities in Australia and Scottish minorities in New Zealand helped to shape the social customs of each country. Other topics covered include the role of Scottish Highlanders in the formation of Scottish national identity, Catholic and Presbyterian religious influences on education systems in Australia and New Zealand, and the impact of political leaders such as John McKenzie, Robert Gordon Menzies, and John Robertson.

We undertook deep sequencing of gill transcriptomes from two freshwater crayfish, Cherax cainii and Cherax destructor , in order to generate genomic resources for future genomics research. Over 83 and 100 million high quality (quality score (Q) ≥ 30) paired-end Illumina reads (150 bp) were assembled into 147,101 and 136,622 contigs in C. cainii and C. destructor , respectively. A total of 24,630 and 23,623 contigs received significant BLASTx hits and allowed the identification of multiple gill expressed candidate genes associated with pH and salinity balance. These functionally annotated transcripts will provide a resource to facilitate comparative genomic research in the genus Cherax, and in particular allow insights into respiratory and osmoregulatory physiology of this group of animals. [ABSTRACT FROM AUTHOR]