Principles of Stress-Strength Modelling of the Highly Thermally Loaded Materials—The Influence of an Effect of Strength Differential on the Material Effort

This paper presents an improvement in the Huber–Mises–Hencky (HMH) material effort hypothesis proposed by Burzyński. Unlike the HMH hypothesis, it differentiates the plastic effort between compression and tensile load states, and links shear with tensile limit. Furthermore, it considers the fact that construction materials do not have infinite resistance in the pure tensile hydrostatic load state, which was proved by the static load experiment performed on St12T heat-resistant steel. The asymmetry between tensile and compressive loads is captured by the elastic region asymmetry coefficient ϰ, which was established by experiment for St12T steel in the temperature range between 20 °C and 800 °C.

Wolves at the Door: A Closer Look at Hedge Fund Activism

Most investor coordination remains undisclosed. I provide empirical evidence on the extent and consequences of investor coordination in the context of hedge fund activism, in which potential benefits and costs from coordination are especially pronounced. In particular, I examine whether hedge fund activists orchestrate “wolf packs”—that is, groups of investors willing to acquire shares in the target firm before the activist’s campaign is publicly disclosed via a 13D filing—as a way to support the campaign and strengthen the activist’s bargaining position. Using a novel hand-collected data set, I develop a method to identify the formation of wolf packs before the 13D filing. I investigate two competing hypotheses: the Coordinated Effort Hypothesis (wolf packs are orchestrated by lead activists to circumvent securities regulations about “groups” of investors) and the Spontaneous Formation Hypothesis (wolf packs spontaneously arise because investors independently monitor and target the same firms at about the same time). A number of tests rule out the Spontaneous Formation Hypothesis and provide support for the Coordinated Effort Hypothesis. Finally, the presence of a wolf pack is associated with various measures of the campaign’s success. This paper was accepted by Brian Bushee, accounting.

Questioning the Effort Hypothesis That Depressed Patients Perform Disproportionately Worse on Effortful Cognitive Tasks

The debate over Hasher and Zacks’ effort hypothesis—that performance on effortful tasks by patients with depression will be disproportionately worse than their performance on automatic tasks—shows a need for additional research to settle whether or not this notion is “clinical lore.” In this study, we categorized 285 outpatient recipients of neuropsychological evaluations into three groups—No Depression, Mild-to-Moderate Depression, and Severe Depression—based on their Beck Depression Inventory-2 self-reports. We then compared these groups’ performances on both “automatic” and “effortful” versions of the Ruff 2 & 7 Selective Attention Test Total Speed and Total Accuracy Indices, the Digit Span subtest from the Wechsler Adult Intellectual Scale—Fourth Edition, and Trail Making Test Parts A and B, using a two-way (3 × 2) mixed multivariate analysis of variance. Patients with Mild-to-Moderate Depression or Severe Depression performed disproportionately worse than patients with No Depression in our sample on more effortful versions of only one of the four attention or executive functioning measures (Trail Making Test). Thus, these data failed to fully support a hypothesis of disproportionately worse performance on more effortful tasks. While this study failed to negate the effort hypothesis in some specific instances, particularly for use in the Trail Making Test, there is cause for caution in routinely applying the effort hypothesis when interpreting test findings in most clinical settings and for most measures.

Does Item Difficulty Affect the Magnitude of the Retrieval Practice Effect? An Evaluation of the Retrieval Effort Hypothesis

Retrieving information by testing improves subsequent retention more than restudy, a phenomenon known as the retrieval practice effect. According to the retrieval effort hypothesis (REH), difficult items require more retrieval effort than easier items and, consequently, should benefit more from retrieval practice. In two experiments, we tested this prediction. Participants learned sets of easy and difficult Swahili–Portuguese word pairs (study phase) and repeatedly restudied half of these items and repeatedly retrieval practiced the other half (practice phase). Forty-eight hours later, they took a cued-recall test (final test phase). In both experiments, we replicated both the retrieval practice and the item difficulty effects. In Experiment 1 (N = 51), we found a greater retrieval practice effect for easy items, MDifference = .26, SD = .17, than for difficult items, MDifference = .19, SD = .19, t(50) = 2.01, p = .05, d = 0.28. In Experiment 2 (N = 28), we found a nonsignificant trend—F(1, 27) = 2.86, p = .10, $$ {\upeta}_{\mathrm{p}}^2 $$ = .10—toward a greater retrieval practice effect for difficult items, MDifference = .28, SD = .22, than for easy items, MDifference = .18, SD = .21. This was especially true for individuals who benefit from retrieval practice (difficult: MDifference = .32, SD = .18; easy: MDifference = .20, SD = .20), t(24) = –2.08, p = .05, d = –0.42. The results provide no clear evidence for the REH and are discussed in relation to current accounts of the retrieval practice effect.

An examination of the effort hypothesis for the perceived strength of passwords

Previous work has examined whether keyboards that have multiple levels of entry (e.g., soft keyboards, found on mobile devices) increase users’ perceptions of password security. That work found that passwords that required greater numbers of keyboard transitions had higher perceived strength. Unfortunately, it was impossible to determine whether this increase in perceived strength was due solely to the extra keyboard transition steps or whether the inclusion of special characters in the passwords (which is required in order to increase the number of keyboard transitions) was driving that perception. The research described in this paper aims to disambiguate these two possibilities. In these experiments, rather than typing the passwords on keyboards, the users simply spoke the password. In this case, there is no additional effort or keypress required in order to enter the special character(s). Results showed that there was a positive correlation between the perceived password strength and the number of keyboard transition for spoken passwords, in a fashion nearly identical to the typed password study. This suggests that the increase in perceived password strength cannot be explained simply as a function of the additional expended effort required to enter additional keyboard transition steps, although it may play a role.

Does concealing familiarity evoke other processes than concealing untrustworthiness? – Different forms of concealed information modulate P3 effects

It was investigated whether concealing learned stimulus attributes (i.e., trustworthiness vs. untrustworthiness) has similar effects on the P3 amplitude than concealing stimulus familiarity. According to salience hypothesis, known, deceptive stimuli (probe) are (perceived) more relevant than truthful, unknown stimuli (irrelevant) evoking a more positive probe P3 amplitude. When all stimuli are known, concealing information is more cognitively demanding than non-concealing information evoking a less positive P3 amplitude according to the mental effort account. Ninety-seven participants concealed knowledge of previously learned faces in the familiarity condition (probe vs. irrelevant stimuli). In the trustworthiness condition, participants concealed untrustworthiness to previously learned faces and responded truthfully to previously learned trustworthy and untrustworthy faces (known, concealed vs. known, truthful stimuli). The parietal mean P3 amplitude was more positive for probe stimuli than for irrelevant stimuli in the familiarity condition providing evidence for the salience hypothesis. In the trustworthiness condition, concealing untrustworthiness showed the smallest parietal mean P3 amplitude suggesting evidence for the mental effort hypothesis. Individual differences of perpetrator’s sensitivity to injustice modulated the P3 amplitude in the trustworthiness condition.

The Accuracy of Metacomprehension Judgments: The Biasing Effect of Text Order

Introduction. Two experiments tested the hypothesis that relative metacomprehension accuracy is vulnerable when readers’ cognitive efforts are biased by text order. It is proposed that the difficulty level of initial text information biases readers’ estimates of text comprehension but is correctable when more cognitive effort is applied.Method. In both experiments, participants were randomly assigned to read a series of expository texts in one of two text order conditions: easy-to-hard and hard-to-easy. Readers made estimates of their comprehension and took comprehension tests over their understanding of the texts in the series in order to determine relative metacomprehension accuracy.Results. Experiment 1 revealed that reading texts ordered easy-to-hard resulted in lower average relative metacomprehension accuracy compared to texts ordered hard-to-easy. In Experiment 2, when participants were explicitly instructed to put more cognitive effort in to the task, the biasing effects of text order were eliminated.Discussion and Conclusion. These results expand one tenet of the optimum-effort hypothesis that relative metacomprehension accuracy is minimized when reading is perceived to be easy, requiring little cognitive effort.

Chimpanzee fathers bias their behaviour towards their offspring

Promiscuous mating was traditionally thought to curtail paternal investment owing to the potential costs of providing care to unrelated infants. However, mounting evidence suggests that males in some promiscuous species can recognize offspring. In primates, evidence for paternal care exists in promiscuous Cercopithecines, but less is known about these patterns in other taxa. Here, we examine two hypotheses for paternal associations with lactating mothers in eastern chimpanzees ( Pan troglodytes schweinfurthii ): paternal effort, whereby males associate and interact more with their own infants, and mating effort, whereby males invest in mothers and offspring for mating privileges. We found that fathers associated more with their offspring than they did with non-kin infants, particularly early in life when infanticide risk is highest. Additionally, fathers and their infant offspring interacted more than expected. Notably, association between fathers and mother–infant pairs did not predict the probability of siring the mother's next offspring. Our results support the paternal effort, but not the mating effort hypothesis in this species. Chimpanzees are one of the most salient models for the last common ancestor between Pan and Homo , thus our results suggest that a capacity for paternal care, possibly independent of long-term mother–father bonds, existed early in hominin evolution.