Negative density-dependent dispersal in tsetse (Glossina spp): An artefact of inappropriate analysis

Published analysis of genetic material from field-collected tsetse (Glossina spp, primarily from the Palpalis group) has been used to predict that the distance (δ) dispersed per generation increases as effective population densities (De) decrease, displaying negative density-dependent dispersal (NDDD). Using the published data we show this result is an artefact arising primarily from errors in estimates of S, the area occupied by a subpopulation, and thereby in De. The errors arise from the assumption that S can be estimated as the area (S^) regarded as being covered by traps. We use modelling to show that such errors result in anomalously high correlations between δ^ and S^ and the appearance of NDDD, with a slope of -0.5 for the regressions of log(δ^) on log(D^e), even in simulations where we specifically assume density-independent dispersal (DID). A complementary mathematical analysis confirms our findings. Modelling of field results shows, similarly, that the false signal of NDDD can be produced by varying trap deployment patterns. Errors in the estimates of δ in the published analysis were magnified because variation in estimates of S were greater than for all other variables measured, and accounted for the greatest proportion of variation in δ^. Errors in census population estimates result from an erroneous understanding of the relationship between trap placement and expected tsetse catch, exacerbated through failure to adjust for variations in trapping intensity, trap performance, and in capture probabilities between geographical situations and between tsetse species. Claims of support in the literature for NDDD are spurious. There is no suggested explanation for how NDDD might have evolved. We reject the NDDD hypothesis and caution that the idea should not be allowed to influence policy on tsetse and trypanosomiasis control.

Many Labs 5: Registered Replication of Förster, Liberman, and Kuschel’s (2008) Study 1

In a test of their global-/local-processing-style model, Förster, Liberman, and Kuschel (2008) found that people assimilate a primed concept (e.g., “aggressive”) into their social judgments after a global prime (e.g., they rate a person as being more aggressive than do people in a no-prime condition) but contrast their judgment away from the primed concept after a local prime (e.g., they rate the person as being less aggressive than do people in a no prime-condition). This effect was not replicated by Reinhard (2015) in the Reproducibility Project: Psychology. However, the authors of the original study noted that the replication could not provide a test of the moderation effect because priming did not occur. They suggested that the primes might have been insufficiently applicable and the scenarios insufficiently ambiguous to produce priming. In the current replication project, we used both Reinhard’s protocol and a revised protocol that was designed to increase the likelihood of priming, to test the original authors’ suggested explanation for why Reinhard did not observe the moderation effect. Teams from nine universities contributed to this project. We first conducted a pilot study ( N = 530) and successfully selected ambiguous scenarios for each site. We then pilot-tested the aggression prime at five different sites ( N = 363) and found that it did not successfully produce priming. In agreement with the first author of the original report, we replaced the prime with a task that successfully primed aggression (hostility) in a pilot study by McCarthy et al. (2018). In the final replication study ( N = 1,460), we did not find moderation by protocol type, and judgment patterns in both protocols were inconsistent with the effects observed in the original study. We discuss these findings and possible explanations.

The Relation Between the Degree of Synaesthesia, Autistic Traits, and Local/Global Visual Perception

In individuals with synaesthesia specific sensory stimulation leads to unusual concurrent perceptions in the same or a different modality. Recent studies have demonstrated a high co-occurrence between synaesthesia and autism spectrum disorder (ASD), a condition also characterized by altered perception. A potentially shared characteristic of synaesthesia and ASD is a bias towards local (detail-focussed) perception. We investigated whether a bias towards local perception is indeed shared between synaesthesia and ASD. In a neurotypical population, we studied the relation between the degree of autistic traits (measured by the AQ) and the degree of grapheme-colour synaesthesia (measured by a consistency task), as well as whether both are related to a local bias in tasks assessing local/global visual perception. A positive correlation between total AQ scores and the degree of synaesthesia was found. Our study extends previous studies that found a high ASD-synaesthesia co-occurrence in clinical populations. Consistent with the hypothesized local perceptual bias in ASD, scores on the AQ-attention to detail subscale were related to increased performance on an Embedded Figures Task (EFT), and we found evidence for a relation to reduced susceptibility to visual illusions. We found no relation between autistic traits and local visual perception in a motion coherence task (MCT). Also, no relation between synaesthesia and local visual perception was found, although a reduced susceptibility to visual illusions resembled the results obtained for AQ-atttention to detail subscale. A suggested explanation for the absence of a relationship between the degree of synaesthesia and a local bias is that a possible local bias might be more pronounced in supra-threshold synaesthetes (compared to neurotypicals).

Episodic memory as an explanation for the insurance hypothesis in obesity

In evaluating the insurance hypothesis as an explanation for obesity, we propose one missing piece of the puzzle. Our suggested explanation for why individuals report food insecurity is that an individual may have an impaired episodic ability to plan for the future.

Accounting for variability in Malayo-Polynesian pronouns

This article is a suggested explanation for the multiple variants of the forms of some Malayo-Polynesian pronouns that have been characterized as the result of drift. The explanation that is given is referred to here as paradigmatic instability, a phenomenon not previously discussed with reference to these problems. In the cases discussed in this article it is the avoidance of forms that are semantically or pragmatically inappropriate within the context of the paradigm in which they occur which renders the forms morphologically variable and the paradigms in which they occur unstable. In Malayo-Polynesian languages, it is the avoidance of a form that is reconstructed as a plural pronoun in Proto-Austronesian but which in all Malayo-Polynesian daughter languages is found as a singular pronoun. Where this form is retained as part of some other plural forms, it has been lost or modified in a wide range of variants in the daughter languages.

Impact Toughness for PM HIP 316L at Cryogenic Temperatures

It is well known throughout the PM HIP (Powder Metallurgy Hot Isostatic Pressing) industry that PM HIPed 316L material in general exhibit higher strength than conventional 316L. However, previous studies have shown an uncharacteristic behavior in impact toughness properties at cryogenic temperatures compared to conventional forged material. The uncharacteristic behavior consists of unexpectedly large drop in impact toughness at cryogenic temperatures which is not seen in the same extent in conventional material e.g. forged 316L. With the recent code case approval for PM HIPed 316L material, this behavior can be seen as an uncertainty regarding the performance of the material and its use in nuclear applications can therefore become limited. The behavior and underlying mechanisms is yet to be explained in detail. One possible explanation is that it is caused by oxides in the material, of which a large amount originates from oxygen picked up by the very large surface area of the powder during the manufacturing process. The correlation between impact toughness at room temperature and oxygen content is often referred to. In this study the non-metallic inclusion content is correlated to the impact properties at −196°C (−321°F), and a suggested explanation for the behavior of PM HIP 316L/316LN vs. conventional 316L is presented. The size and number of inclusions constitutes a major difference between the PM HIPed and conventional material. The results show that the size of the inclusions is significantly smaller in the PM materials compared to the conventional material and as a consequence they are present in larger numbers in the PM materials. Furthermore, the results clearly show the correlation between inclusion content and the impact toughness at cryogenic temperatures. The correlation is not as clear at room temperature where the different materials behave more similar. The suggested explanation is further supported by literature on cryogenic properties of 316L/316LN, 316L weld material and PM HIP 316LN with greatly reduced oxygen content. The impact toughness testing was performed using instrumented test equipment capable of recording load vs. displacement during testing. From this data the crack propagation and crack initiation energy can be estimated. Furthermore, it is known that grain size can influence mechanical properties. In this study no clear relationship between impact toughness and grain size could be observed. However, a correlation between the grain size and the amount of inclusions in the material was observed. It was found that larger amounts of inclusions in the PM HIPed material are correlated to a finer grain size. The results indicate that the inclusion particles inhibit grain growth during the HIP and heat treatment process by pinning of grain boundaries.

Evidence on Adverse Selection and Establishment Size in the Labor Market

A commonly suggested explanation for the finding that laid-off workers have greater mean post-displacement earnings losses than workers who lose their jobs through plant closings is that the former are of lower quality than the latter. But there is also an alternative explanation for this result: laid-off workers suffer larger earnings losses because, as a group, they have more to lose in the first place, having been displaced from larger, higher-wage establishments. An analysis of data from the National Longitudinal Survey of Youth confirms this hypothesis. Accounting for establishment size removes virtually all of the difference in wage losses for the two groups of displaced workers.