Does Expert Advice Improve Educational Choice?

This paper reports evidence that an individual meeting with a study counselor at high school significantly improves the quality of choice of tertiary educational field, as self-assessed 18 months after graduation from college. To address endogeneity, we explore the variation in study counseling practices between schools as an instrumental variable (IV). Following careful scrutiny of the validity of the IV, our results indicate a significant and positive influence of study counseling on the quality of educational choice, foremost among males and those with low educated parents. The overall result is stable across a number of robustness checks.     

Consequences of Cathodal Stimulation for Behavior: When Does It Help and When Does It Hurt Performance?

Cathodal Transcranial Direct Current Stimulation (C-tDCS) has been reported, across different studies, to facilitate or hinder performance, or simply to have no tangible effect on behavior. This discrepancy is most prominent when C-tDCS is used to alter a cognitive function, questioning the assumption that cathodal stimulation always compromises performance. In this study, we aimed to study the effect of two variables on performance in a simple cognitive task (letter Flanker), when C-tDCS was applied to the left prefrontal cortex (PFC): (1) the time of testing relative to stimulation (during or after), and (2) the nature of the cognitive activity during stimulation in case of post-tDCS testing. In three experiments, we had participants either perform the Flanker task during C-tDCS (Experiment 1), or after C-tDCS. When the Flanker task was administered after C-tDCS, we varied whether during stimulation subjects were engaged in activities that posed low (Experiment 2) or high (Experiment 3) demands on the PFC. Our findings show that the nature of the task during C-tDCS has a systematic influence on the outcome, while timing per se does not.     

Does Early Psychosocial Stress Affect Mate Choice?

Early psychosocial stress (e.g., parental divorce, abuse) is conjectured to place individuals on a developmental trajectory leading to earlier initiation of sexual activity, earlier reproduction, and having more sex partners than those with less early psychosocial stress. But does it also affect an individual’s mate choice? The present study examined whether early psychosocial stress affects preferences and dislikes for opposite-sex faces varying in masculinity/femininity, a putative indicator of mate quality, in premenopausal women (58 with a natural cycle, 53 pill-users) and 196 men. No significant three-way interactions were found when women selected the most or least preferred face with participant group (natural cycle, pill), conception risk (low, high), and early psychosocial stress (low, high) as between-subjects factors. Early psychosocial stress did not affect men’s face preferences when selecting the most preferred face. However, men with high early psychosocial stress disliked masculine faces significantly more so than men with low early psychosocial stress. Overall it was concluded that early psychosocial stress does not affect mate choice with the exception that men with high early psychosocial stress were more likely to dislike masculine female faces. It was suggested that men with high early psychosocial stress may dislike masculine female faces because they have nothing to gain from associating with women with such faces.     

Nebulin: Does It Measure up as a Ruler?

A recent study has shown that the giant protein nebulin maintains the lengths of actin filaments in striated muscle cells. Although on the surface, nebulin looks like a molecular ruler, it may be playing a more complex role in regulating dynamics at the pointed end of actin filaments in striated muscle.     

Does Female Personality Determine Mate Choice Through Sexual Cannibalism?

Animal personalities (e.g. consistent across‐context behavioural differences between individuals) can lead to differences in mate choice. However, evidence for this link remains limited. Pre‐mating sexual cannibalism can be a behavioural syndrome (i.e. a suboptimal personality) in which adaptive female aggression towards heterospecific prey spills over on non‐adaptive aggression towards courting males, independently of the female mating or feeding status (i.e. the ‘aggressive spillover hypothesis’, ASH). On the other hand, sexual cannibalism can also be a form of mate choice by which females selectively kill or mate with males depending on the male phenotype. We introduce the hypothesis that the most aggressive females in the population will not only attack males more frequently, but will be less likely to impose sexual selection on males through sexual cannibalism. Assuming that in a field common garden experiment in which females were fed ad libitum the rate of weight gain by a female may reflect her voracity or aggressiveness, we show that in the cannibalistic burrowing wolf spider Lycosa hispanica (formerly L. tarantula), voracity towards heterospecific prey predicts a female's tendency towards sexual cannibalism. Unmated females with higher weight gains were more cannibalistic and attacked males regardless of the male phenotype. On the other hand, females that were less voracious tended to be less cannibalistic, and when they did kill a male, they were selective, killing males in poorer condition and mating with those in better condition. Our results demonstrate that females with different phenotypes (growth rates) differently imposed selection on male condition, tentatively supporting the hypothesis that female aggression levels can spill over on sexual selection through sexual cannibalism.     

Nonlinear Dynamics of Emotion-Cognition Interaction: When Emotion Does not Destroy Cognition?

Emotion (i.e., spontaneous motivation and subsequent implementation of a behavior) and cognition (i.e., problem solving by information processing) are essential to how we, as humans, respond to changes in our environment. Recent studies in cognitive science suggest that emotion and cognition are subserved by different, although heavily integrated, neural systems. Understanding the time-varying relationship of emotion and cognition is a challenging goal with important implications for neuroscience. We formulate here the dynamical model of emotion-cognition interaction that is based on the following principles: (1) the temporal evolution of cognitive and emotion modes are captured by the incoming stimuli and competition within and among themselves (competition principle); (2) metastable states exist in the unified emotion-cognition phase space; and (3) the brain processes information with robust and reproducible transients through the sequence of metastable states. Such a model can take advantage of the often ignored temporal structure of the emotion-cognition interaction to provide a robust and generalizable method for understanding the relationship between brain activation and complex human behavior. The mathematical image of the robust and reproducible transient dynamics is a Stable Heteroclinic Sequence (SHS), and the Stable Heteroclinic Channels (SHCs). These have been hypothesized to be possible mechanisms that lead to the sequential transient behavior observed in networks. We investigate the modularity of SHCs, i.e., given a SHS and a SHC that is supported in one part of a network, we study conditions under which the SHC pertaining to the cognition will continue to function in the presence of interfering activity with other parts of the network, i.e., emotion.     

Language Acquisition: When Does the Learning Begin?

Language acquisition is quite sophisticated by four months of age. Two cues that babies use to discriminate their language from another are the stress patterns of words and visual cues inherent in language production.     

When Does Gastric Atrophy Develop in Japanese Children?

Background: Long-term Helicobacter pylori infection causes inflammatory sequelae such as atrophy and intestinal metaplasia in the stomach, which is thought to increase the risk of developing gastric malignancy. We previously reported that gastric atrophy can develop in Japanese children with H. pylori infection, predominantly in the antrum. However, detailed data about the age of children with atrophy are largely lacking.
Methods and results: In the present study, 131 children (79 boys) with H. pylori infection were re-analyzed for an association between age and the grade of gastric atrophy. The gastric antrum was histologically evaluated in all 131 patients and the corpus in 46 patients. Grade 2 and 3 antral atrophy was observed in 13 and one patients, respectively: the mean age was 12.1 years. Two patients (11 and 14 years old) had grade 2 corpus atrophy but no patients had grade 3. No significant difference was found in age among patients with grade 0, 1 and 2 or 3 atrophy in the antrum ( p =  .97) and in the corpus ( p =  .59). None of the patients with grade 2 or 3 atrophy had intestinal metaplasia either in the antrum or in the corpus.
Conclusions: The results of the present study require a careful interpretation because of the retrospective analysis. In high-risk countries of gastric cancer, however, eradicating H. pylori in childhood could prove more effective in preventing gastric atrophy, ultimately, the development of cancer.     

When Does Reward Maximization Lead to Matching Law?

What kind of strategies subjects follow in various behavioral circumstances has been a central issue in decision making. In particular, which behavioral strategy, maximizing or matching, is more fundamental to animal''s decision behavior has been a matter of debate. Here, we prove that any algorithm to achieve the stationary condition for maximizing the average reward should lead to matching when it ignores the dependence of the expected outcome on subject''s past choices. We may term this strategy of partial reward maximization “matching strategy”. Then, this strategy is applied to the case where the subject''s decision system updates the information for making a decision. Such information includes subject''s past actions or sensory stimuli, and the internal storage of this information is often called “state variables”. We demonstrate that the matching strategy provides an easy way to maximize reward when combined with the exploration of the state variables that correctly represent the crucial information for reward maximization. Our results reveal for the first time how a strategy to achieve matching behavior is beneficial to reward maximization, achieving a novel insight into the relationship between maximizing and matching.     

Does the Type of Disturbance Matter When Restoring Disturbance‐Dependent Grasslands?

The reintroduction of burning is usually viewed as critical for grassland restoration; but its ecological necessity is often untested. On the one hand, fire may be irreplaceable because it suppresses dominant competitors, eliminates litter, and modifies resource availability. On the other hand, its impacts could be mimicked by other disturbances such as mowing or weeding that suppress dominants but without the risks sometimes associated with burning. Using a 5‐year field experiment in a degraded oak savanna, we tested the impacts of fire, cutting and raking, and weeding on two factors critical for restoration: controlling dominant invasive grasses and increasing subordinate native flora. We manipulated the season of treatment application and used sites with different soil depths because both factors influence fire behavior. We found no significant difference among the treatments—all were similarly effective at suppressing exotics and increasing native plant growth. This occurred because light is the primary limiting resource for many native species and each treatment increased its availability. The effectiveness of disturbance for restoration depended more on the timing of application and site factors than on the type of treatment used. Summer disturbances occurred near their reproductive peak of the exotics, so their mortality approached 100%. Positive responses by native species were significantly greater on shallow soils because these areas had higher native diversity prior to treatment. Although likely not applicable to all disturbance‐dependent ecosystems, these results emphasize the importance of testing the effectiveness of alternative restoration treatments prior to their application.     

Does Environmental Enrichment Reduce Stress? An Integrated Measure of Corticosterone from Feathers Provides a Novel Perspective

Enrichment is widely used as tool for managing fearfulness, undesirable behaviors, and stress in captive animals, and for studying exploration and personality. Inconsistencies in previous studies of physiological and behavioral responses to enrichment led us to hypothesize that enrichment and its removal are stressful environmental changes to which the hormone corticosterone and fearfulness, activity, and exploration behaviors ought to be sensitive. We conducted two experiments with a captive population of wild-caught Clark's nutcrackers (Nucifraga columbiana) to assess responses to short- (10-d) and long-term (3-mo) enrichment, their removal, and the influence of novelty, within the same animal. Variation in an integrated measure of corticosterone from feathers, combined with video recordings of behaviors, suggests that how individuals perceive enrichment and its removal depends on the duration of exposure. Short- and long-term enrichment elicited different physiological responses, with the former acting as a stressor and birds exhibiting acclimation to the latter. Non-novel enrichment evoked the strongest corticosterone responses of all the treatments, suggesting that the second exposure to the same objects acted as a physiological cue, and that acclimation was overridden by negative past experience. Birds showed weak behavioral responses that were not related to corticosterone. By demonstrating that an integrated measure of glucocorticoid physiology varies significantly with changes to enrichment in the absence of agonistic interactions, our study sheds light on potential mechanisms driving physiological and behavioral responses to environmental change.     

When Does Stress End? Evidence of a Prolonged Stress Reaction in Shiftworking Truck Drivers

This study aimed to analyze individual cortisol levels in relation to work conditions, sleep, and health parameters among truck drivers working day shifts (n?=?21) compared to those working irregular shifts (n?=?21). A total of 42 male truck drivers (39.8?±?6.2 yrs) completed questionnaires about sociodemographics, job content, work environment, health, and lifestyle. Rest-activity profiles were measured using actigraphy, and cardiovascular blood parameters were collected. Salivary cortisol samples were obtained: (i) at waking time, (ii) 30?min after waking, and (iii) at bedtime, during both one workday and one day off from work. Irregular-shift workers, compared to day-shift workers, showed significantly higher waist-hip ratio, very-low-density lipoprotein (VLDL) cholesterol, tiredness after work, years working as a driver, truck vibration, and less job demand (p?<?.05). High cortisol levels in irregular-shift workers were correlated with certain stressors, such as short sleep duration and low job satisfaction, and to metabolic parameters, such as total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), VLDL, and triglycerides. Day-shift workers had higher cortisol levels collected 30?min after waking (p?=?.03) and a higher cortisol awakening response (CAR; p?=?.02) during workdays compared to off days. Irregular-shift workers had higher cortisol levels on their off days compared to day-shift workers (p?=?.03). In conclusion, for the day-shift workers, a higher cortisol response was observed on workdays compared to off days. Although no direct comparisons could be made between groups for work days, on off days the irregular-shift workers had higher cortisol levels compared to day-shift workers, suggesting a prolonged stress response in the irregular-shift group. In addition, cortisol levels were correlated with stressors and metabolic parameters. Future studies are warranted to investigate further stress responses in the context of irregular work hours. (Author correspondence: crmoreno@usp.br)     

When Do Latent Class Models Overstate Accuracy for Diagnostic and Other Classifiers in the Absence of a Gold Standard?

Latent class models are increasingly used to assess the accuracy of medical diagnostic tests and other classifications when no gold standard is available and the true state is unknown. When the latent class is treated as the true class, the latent class models provide measures of components of accuracy including specificity and sensitivity and their complements, type I and type II error rates. The error rates according to the latent class model differ from the true error rates, however, and empirical comparisons with a gold standard suggest the true error rates often are larger. We investigate conditions under which the true type I and type II error rates are larger than those provided by the latent class models. Results from Uebersax (1988, Psychological Bulletin 104, 405-416) are extended to accommodate random effects and covariates affecting the responses. The results are important for interpreting the results of latent class analyses. An error decomposition is presented that incorporates an error component from invalidity of the latent class model.     

Does Clinical Depression Affect the Accuracy of Self‐reported Height and Weight in Obese Women?

Objective: Recent research from a self‐report survey showed a strong association between obesity and clinical depression in women. The present analysis assessed whether differential bias in self‐reports of height and weight as a function of depression influences the apparent strength of the association. Methods: Accuracy of self‐reported height and weight was assessed in 250 obese (mean BMI=38.7 kg/m²) women, 135 of whom met the American Psychiatric Association DSM‐IV diagnostic criteria for clinical depression. Results: Depressed and non‐depressed women underreported their weight by 1.5 and 1.2 kg, respectively. They underreported their height by 0.002 and 0.003 m, respectively. Discussion: Bias in self‐reports of body weight and height is similar in depressed and non‐depressed obese women. The underreporting of weight in both groups is similar in magnitude to that seen in normal weight women. Thus, using self‐reports of height and weight seems unlikely to bias estimates of the association between obesity and clinical depression in women.     

The Global Burden of Disease Assessments—WHO Is Responsible?

The Global Burden of Disease (GBD) concept has been used by the World Health Organization (WHO) for its reporting on health information for nearly 10 years. The GBD approach results in a single summary measure of morbidity, disability, and mortality, the so-called disability-adjusted life year (DALY). To ensure transparency and objectivity in the derivation of health information, WHO has been urged to use reference groups of external experts to estimate burden of disease. Under the leadership and coordination of WHO, expert groups have been appraising and abstracting burden of disease information. Examples include the Child Health Epidemiology Reference Group (CHERG), the Malaria Monitoring and Evaluation Reference Group (MERG), and the recently established Foodborne Disease Burden Epidemiology Reference Group (FERG). The structure and functioning of and lessons learnt by these groups are described in this paper. External WHO expert groups have provided independent scientific health information while operating under considerable differences in structure and functioning. Although it is not appropriate to devise a single "best practice" model, the common thread described by all groups is the necessity of WHO's leadership and coordination to ensure the provision and dissemination of health information that is to be globally accepted and valued.     

When condensed matter physics meets biology: Does superhydrophobicity benefiting the cryopreservation of human spermatozoa?

With the increasing demand in regenerative and reproductive medicine for successful conservation of living matter, the need of reliable platform in cell banking seems inevitable. Whilst the cells storage at cryogenic temperatures is a well-developed method, far less is known about the efficiency of nanotechnology in cryogenics. The primary objective of this study is to represent the first of its kind experimental results related to cryopreservation of human spermatozoa by means of superhydrophobic carbon soot coatings. The inclusion of soot-based water repellent interface during the freezing and thawing of human semen minimizes the solid-liquid interfacial area, retards the heat transfer rate and promotes the recovery of up to 80% of initial motility of post-thaw sperm cells. Our discoveries reveal a fundamentally new and exciting direction of development of cryopreservation technologies in the battle against painful biopsies and repetitive surgeries.     

Does Investment in the Sexes Differ When Fathers Are Absent?

This study examines child survival and growth in a patrilineal Ethiopian community as a function of father absence and sex. In line with evolutionary predictions for sex-biased parental investment, the absence of a father and associated constraints on household resources is more detrimental for sons’ than daughters’ survival in infancy. Father absence doubles a son’s risk of dying in infancy but has a positive influence on the well-being of female members of the household, improving daughter survival, growth, and maternal nutritional status. Lack of paternal investment may be compensated for by other matrilateral kin through increased reciprocity between mother, daughter, and sister.