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Arbitrage pricing theory, the stochastic discount factor and estimation of risk premia from portfolios
Get PDFThe arbitrage pricing theory (APT) attributes differences in expected returns to exposure to systematic risk factors. Two aspects of the APT are considered. Firstly, the factors in the statistical asset pricing model are related to a theoretically consistent set of factors defined by their conditional covariation with the stochastic discount factor (SDF) used to price securities within inter-temporal asset pricing models. It is shown that risk premia arise from non-zero correlation of observed factors with SDF and the pricing errors arise from the correlation of the errors in the statistical model with SDF. Secondly, the estimates of factor risk premia using portfolios are compared to those obtained using individual securities. It is shown that in the presence of pricing errors consistent estimation of risk premia requires a large number of not fully diversified portfolios. Also, in general, it is not possible to rank estimators using individual securities and portfolios in terms of their small sample bias
As we like it: did the UK’s 2016 EU referendum reveal the “Will of the People?”
Get PDFSince the UK’s 2016 referendum on EU membership, politicians on both sides of the debate have repeatedly invoked the “will of the people,” either to claim that the matter is settled or to justify the need for subsequent confirmatory action. Following a long tradition of information effects research in political science, we argue that the extent to which voters are informed about politically relevant issues is a key factor in evaluating whether any given result accurately reflects an electorate’s collective “will.” By using counterfactual modeling applied to British Election Study data, we estimate that support for leaving the EU would have dropped by 7-10 percentage points, had voters been more fully informed. More generally, in the context of relatively infrequent referenda, we suggest that such models can usefully indicate the sensitivity of outcomes to different levels of information, and allow legislators to gauge the extent to which a given outcome likely reflects voters’ collective will
Interpersonal perception of emotional intensity by English first (L1) and foreign (LX) language users in audio(visual) communication.
Get PDFMany studies have revealed multilinguals’ reduced emotionality of a foreign language (LX) compared to a first language (L1). Contrary to the bulk of research so far, which has focused on multilinguals’ own emotion experience or emotion processing, this study focuses on interpersonal communication and investigates how one perceives the intensity level of someone else’s emotional experience. Data were collected via an online survey. A total of 557 L1 users and 811 upper-intermediate to advanced LX users of English rated the intensity of the emotional experience of a British actress enacting different emotional events in six audiovisual or audio-only clips in English. Overall, audiovisual stimuli yielded higher intensity ratings than audio-only stimuli. More surprisingly, the L1 participants’ intensity ratings were lower than the LX participants’ ratings in both conditions. English proficiency was not significantly correlated with intensity ratings among L1 and LX users, which suggests that paralinguistic skills develop independently from linguistic skills
'Staple of the Contemporary Music Scene': Roberto Gerhard in geopolitical perspective
Get PDFBook synopsis: Gerhard was one of the most visionary composers of the twentieth century drawing together ideas from science, philosophy, and the arts into an oeuvre that encompasses the folk song of his native Catalonia, to serialism and electronic music. The composer lived through some of the most tumultuous times in recent memory including the Spanish Civil War and the Second World War as an exile in England. This edited volume uniquely brings together specialists in Spanish cultural studies, exile, musicology, and analysis to explore how these events and the post-war cultural and political climate shaped Gerhard's life and work
Cultural values as policy directives: techniques, technologies and symbolic work
No full textCultural policies aim to respond to the widespread use of digital technologies in cultural practices by facilitating their application and addressing associated challenges. In arguing that policy positions emerge through the interface of digital technologies and culture and that they need to be negotiated in practice, this paper discusses how digital technologies are perceived and negotiated in traditional cultures of making. The immersive nature of cultural values is made explicit through symbolic work that embeds the digital as documentation of the life cycle of hand-woven materials. Applying the framework of cultural techniques, digital technologies are perceived as products of culture. They signify the interwoven complexities of values between people, cultural practice and materials recognising cultures of making as policy directives
Stratifying the autistic phenotype using electrophysiological indices of social perception
No full textAutism spectrum disorder (ASD) is a neurodevelopmental condition characterized by difficulties in social communication, but also great heterogeneity. To offer individualized medicine approaches, we need to better target interventions by stratifying autistic people into subgroups with different biological profiles and/or prognoses. We sought to validate neural responses to faces as a potential stratification factor in ASD by measuring neural (electroencephalography) responses to faces (critical in social interaction) in N = 436 children and adults with and without ASD. The speed of early-stage face processing (N170 latency) was on average slower in ASD than in age-matched controls. In addition, N170 latency was associated with responses to faces in the fusiform gyrus, measured with functional magnetic resonance imaging, and polygenic scores for ASD. Within the ASD group, N170 latency predicted change in adaptive socialization skills over an 18-month follow-up period; data-driven clustering identified a subgroup with slower brain responses and poor social prognosis. Use of a distributional data-driven cutoff was associated with predicted improvements of power in simulated clinical trials targeting social functioning. Together, the data provide converging evidence for the utility of the N170 as a stratification factor to identify biologically and prognostically defined subgroups in ASD
Adversarial robustness of deep code comment generation
Get PDFDeep neural networks (DNNs) have shown remarkable performance in a variety of domains such as computer vision, speech recognition, and natural language processing. Recently they also have been applied to various software engineering tasks, typically involving processing source code. DNNs are well-known to be vulnerable to adversarial examples, i.e., fabricated inputs that could lead to various misbehaviors of the DNN model while being perceived as benign by humans. In this paper, we focus on the code comment generation task in software engineering and study the robustness issue of the DNNs when they are applied to this task. We propose ACCENT(Adversarial Code Comment gENeraTor), an identifier substitution approach to craft adversarial code snippets, which are syntactically correct and semantically close to the original code snippet, but may mislead the DNNs to produce completely irrelevant code comments. In order to improve the robustness, ACCENT also incorporates a novel training method, which can be applied to existing code comment generation models. We conduct comprehensive experiments to evaluate our approach by attacking the mainstream encoder-decoder architectures on two large-scale publicly available datasets. The results show that ACCENT efficiently produces stable attacks with functionality-preserving adversarial examples, and the generated examples have better transferability compared with the baselines. We also confirm, via experiments, the effectiveness in improving model robustness with our training method
Heritability of psychotic experiences in adolescents and interaction with environmental risk
Get PDFImportance Genetic risk factors are known to play a role in the etiology of psychotic experiences in the general population. Little is known about whether these risk factors interact with environmental risks for psychotic experiences.
Objective To assess etiological heterogeneity and exposure to environmental risks associated with psychotic experiences in adolescence using the twin design.
Design, Setting, and Participants This twin study, conducted from December 1, 2014, to August 31, 2020, included a UK-based sample of twin pairs aged 16 years. This investigation evaluated the extent to which the genetic variance underlying psychotic experiences and the magnitude of the heritability of psychotic experiences was moderated by exposure to 5 environmental risk factors (bullying, dependent life events, cannabis use, tobacco use, and low birth weight). Psychotic experiences were assessed by 5 self-reported measures and 1 parent-reported measure. Participants’ exposure to environmental risks was assessed at birth and age 12 to 16 years. Structural equation models were used to assess differences in the variance in and heritability of psychotic experiences across these exposures, while controlling for gene-environment correlation effects. Analyses were repeated in an independent Swedish sample. Data analyses were performed from September 1, 2018, to August 31, 2020.
Main Outcomes and Measures Primary outcome measures were exposure to environmental factors, as measured by a composite score, and psychotic experiences.
Results A total of 4855 twin pairs (1926 female same-sex pairs, 1397 male same-sex pairs, and 1532 opposite-sex pairs) were included from the Twins Early Development Study (TEDS), and 6435 twin pairs (2358 female same-sex pairs, 1861 male same-sex pairs, and 2216 opposite-sex pairs) were included from the Child and Adolescent Twin Study in Sweden (CATSS). Mean age of twins from TEDS was 16.5 years. Mean age of twins from CATSS was 18.6 years. More exposure to environmental risk factors was associated with having more psychotic experiences. The relative contribution of genetic influences to psychotic experiences was lower with increasing environmental exposure for paranoia (44%; 95% CI, 33%-53% to 38%; 95% CI, 14%-58%), cognitive disorganization (47%; 95% CI, 38%-51% to 32%; 95% CI, 11%-45%), grandiosity (41%; 95% CI, 29%-52% to 32%; 95% CI, 9%-48%), and anhedonia (49%; 95% CI, 42%-53% to 37%; 95% CI, 15%-54%). This pattern was replicated for the measure of psychotic experiences in the independent Swedish replication sample. The heritability of hallucinations and parent-rated negative symptoms remained relatively constant.
Conclusions and Relevance Findings of this twin study suggest that environmental factors play a greater role in the etiology of psychotic experiences than genetic factors. The relative importance of environmental factors is even higher among individuals exposed to environmental risks for psychotic experiences, highlighting the importance of a diathesis-stress or bioecological framework for understanding adolescent psychotic experiences
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