Foraging rates from metabarcoding: Predators have reduced functional responses in wild, diverse prey communities.

Functional responses describe foraging rates across prey densities and underlie many fundamental ecological processes. Most functional response knowledge comes from simplified lab experiments, but we do not know whether these experiments accurately represent foraging in nature. In addition, the difficulty of conducting multispecies functional response experiments means that it is unclear whether interaction strengths are weakened in the presence of multiple prey types. We developed a novel method to estimate wild predators' foraging rates from metabarcoding data and use this method to present functional responses for wild wolf spiders foraging on 27 prey families. These field functional responses were considerably reduced compared to lab functional responses. We further find that foraging is sometimes increased in the presence of other prey types, contrary to expectations. Our novel method for estimating field foraging rates will allow researchers to determine functional responses for wild predators and address long-standing questions about foraging in nature.

Influence of intravenous fentanyl or dexmedetomidine infusions, combined with lidocaine and ketamine, on cardiovascular response, sevoflurane requirement and postoperative pain in dogs anesthetized for unilateral mastectomy.

OBJECTIVE: To compare the effects of constant rate infusions (CRI) of fentanyl or dexmedetomidine, combined with lidocaine and ketamine, on cardiovascular response during surgery, sevoflurane requirement and postoperative pain in dogs undergoing mastectomy. STUDY DESIGN: Prospective, randomized, blinded, clinical trial. ANIMALS: A total of 29 female dogs with mammary tumors. METHODS: Premedication consisted of intramuscular acepromazine and morphine. General anesthesia was induced with intravenous propofol and maintained with sevoflurane. Dogs were randomized to be administered intravenous DLK [dexmedetomidine 1 µg kg-1 loading dose (LD) and 1 µg kg-1 hour-1; lidocaine 2 mg kg-1 LD and 3 mg kg-1 hour-1; ketamine 1 mg kg-1 LD and 0.6 mg kg-1 hour-1; n = 14] or FLK (fentanyl 5 µg kg-1 LD and 9 µg kg-1 hour-1; same doses of lidocaine and ketamine; n = 15) during anesthesia. Cardiorespiratory variables and end-tidal sevoflurane (Fe'Sevo) were recorded during surgery. The number of dogs administered ephedrine to treat arterial hypotension [mean arterial pressure (MAP) < 60 mmHg] was recorded. Meloxicam was administered to both groups. Postoperative pain and rescue analgesia requirement were assessed for 24 hours using the short form of the Glasgow Composite Measure Pain Scale. Data were compared using a mixed effects model or a Mann-Whitney test. RESULTS: More dogs required ephedrine in FLK than in DLK (67% versus 7%). Heart rate was not significantly different between groups, whereas lower values of MAP (p ≤ 0.01) and Fe'Sevo (p = 0.018) were observed in FLK than in DLK. Rescue analgesia was administered to 2/15 dogs in FLK and 0/14 dogs in DLK. CONCLUSIONS AND CLINICAL RELEVANCE: Based on the cardiovascular response during surgery, intraoperative infusions of FLK and DLK provided adequate antinociception. Infusion of DLK provided greater stability of blood pressure. Both protocols resulted in minimal need for additional analgesia within 24 hours postoperatively.

Intraguild predation is increased in areas of low prey diversity in a generalist predator community.

Niche differentiation and intraguild predation (IGP) can allow ecologically similar species to coexist, although it is unclear which coexistence mechanism predominates in consumer communities. Until now, a limited ability to quantify diets from metabarcoding data has precluded the use of sequencing data to determine the relative importance of these mechanisms. Here, we pair a recent metabarcoding quantification approach with stable isotope analysis to examine diet composition in a wolf spider community. We compare the prevalence of resource partitioning and IGP in these spiders and test whether factors that influence foraging performance, including individual identity, morphology, prey community and environmental conditions, can explain variation in diet composition and IGP. Extensive IGP is likely the primary coexistence mechanism in this community, and other factors to which foraging variation is often attributed do not explain diet composition and IGP here. Rather, IGP increases as prey diversity decreases. Foragers are driven to IGP where resource niches are limited. We highlight the need to examine how drivers of predator-prey interaction strengths translate into foraging in natural systems.

No intrinsic number bias: Evaluating the role of perceptual discriminability in magnitude categorization.

Accumulating evidence suggests that there is a spontaneous preference for numerical, compared to non-numerical (e.g., cumulative surface area), information. However, given a paucity of research on the perception of non-numerical magnitudes, it is unclear whether this preference reflects a specific bias towards number, or a general bias towards the more perceptually discriminable dimension (i.e., number). Here, we found that when the number and area of visual dot displays were matched in mathematical ratio, number was more perceptually discriminable than area in both adults and children. Moreover, both adults and children preferentially categorized these ratio-matched stimuli based on number, consistent with previous work. However, when number and area were matched in perceptual discriminability, a different pattern of results emerged. In particular, children preferentially categorized stimuli based on area, suggesting that children's previously observed number bias may be due to a mismatch in the perceptual discriminability of number and area, not an intrinsic salience of number. Interestingly, adults continued to categorize the displays on the basis of number. Altogether, these findings suggest a dominant role for area during childhood, refuting the claim that number is inherently and uniquely salient. Yet they also reveal an increased salience of number that emerges over development. Potential explanations for this developmental shift are discussed. RESEARCH HIGHLIGHTS: Previous work found that children and adults spontaneously categorized dot array stimuli by number, over other magnitudes (e.g., area), suggesting number is uniquely salient. However, here we found that when number and area were matched by ratio, as in prior work, number was significantly more perceptually discriminable than area. When number and area were made equally discriminable ('perceptually-matched'), children, contra adults, spontaneously categorized stimuli by area over number (and other non-numerical magnitudes). These findings suggest that area may be uniquely salient early in childhood, with the previously-observed number bias not emerging until later in development.

Opposing roles of the entero-pancreatic hormone urocortin-3 in glucose metabolism in rats.

AIM/HYPOTHESIS: Urocortin-3 (UCN3) is a glucoregulatory peptide produced in the gut and pancreatic islets. The aim of this study was to clarify the acute effects of UCN3 on glucose regulation following an oral glucose challenge and to investigate the mechanisms involved. METHODS: We studied the effect of UCN3 on blood glucose, gastric emptying, glucose absorption and secretion of gut and pancreatic hormones in male rats. To supplement these physiological studies, we mapped the expression of UCN3 and the UCN3-sensitive receptor, type 2 corticotropin-releasing factor receptor (CRHR2), by means of fluorescence in situ hybridisation and by gene expression analysis. RESULTS: In rats, s.c. administration of UCN3 strongly inhibited gastric emptying and glucose absorption after oral administration of glucose. Direct inhibition of gastrointestinal motility may be responsible because UCN3's cognate receptor, CRHR2, was detected in gastric submucosal plexus and in interstitial cells of Cajal. Despite inhibited glucose absorption, post-challenge blood glucose levels matched those of rats given vehicle in the low-dose UCN3 group, because UCN3 concomitantly inhibited insulin secretion. Higher UCN3 doses did not further inhibit gastric emptying, but the insulin inhibition progressed resulting in elevated post-challenge glucose and lipolysis. Incretin hormones and somatostatin (SST) secretion from isolated perfused rat small intestine was unaffected by UCN3 infusion; however, UCN3 infusion stimulated secretion of somatostatin from delta cells in the isolated perfused rat pancreas which, unlike alpha cells and beta cells, expressed Crhr2. Conversely, acute antagonism of CRHR2 signalling increased insulin secretion by reducing SST signalling. Consistent with these observations, acute drug-induced inhibition of CRHR2 signalling improved glucose tolerance in rats to a similar degree as administration of glucagon-like peptide-1. UCN3 also powerfully inhibited glucagon secretion from isolated perfused rat pancreas (perfused with 3.5 mmol/l glucose) in a SST-dependent manner, suggesting that UCN3 may be involved in glucose-induced inhibition of glucagon secretion. CONCLUSIONS/INTERPRETATION: Our combined data indicate that UCN3 is an important glucoregulatory hormone that acts through regulation of gastrointestinal and pancreatic functions.

The Effect of Cognitive Load on Auditory Susceptibility During Automated Driving.

OBJECTIVE: We experimentally test the effect of cognitive load on auditory susceptibility during automated driving. BACKGROUND: In automated vehicles, auditory alerts are frequently used to request human intervention. To ensure safe operation, human drivers need to be susceptible to auditory information. Previous work found reduced susceptibility during manual driving and in a lesser amount during automated driving. However, in practice, drivers also perform nondriving tasks during automated driving, of which the associated cognitive load may further reduce susceptibility to auditory information. We therefore study the effect of cognitive load during automated driving on auditory susceptibility. METHOD: Twenty-four participants were driven in a simulated automated car. Concurrently, they performed a task with two levels of cognitive load: repeat a noun or generate a verb that expresses the use of this noun. Every noun was followed by a probe stimulus to elicit a neurophysiological response: the frontal P3 (fP3), which is a known indicator for the level of auditory susceptibility. RESULTS: The fP3 was significantly lower during automated driving with cognitive load compared with without. The difficulty level of the cognitive task (repeat or generate) showed no effect. CONCLUSION: Engaging in other tasks during automated driving decreases auditory susceptibility as indicated by a reduced fP3. APPLICATION: Nondriving task can create additional cognitive load. Our study shows that performing such tasks during automated driving reduces the susceptibility for auditory alerts. This can inform designers of semi-automated vehicles (SAE levels 3 and 4), where human intervention might be needed.

Perceived number is not abstract.

To support the claim that the approximate number system (ANS) represents rational numbers, Clarke and Beck (C&B) argue that number perception is abstract and characterized by a second-order character. However, converging evidence from visual illusions and psychophysics suggests that perceived number is not abstract, but rather, is perceptually interdependent with other magnitudes. Moreover, number, as a concept, is second-order, but number, as a percept, is not.

Does training mental rotation transfer to gains in mathematical competence? Assessment of an at-home visuospatial intervention.

The current study examined whether the effect of spatial training transfers to the math domain. Sixty-two 6- and 7-year-olds completed an at-home 1-week online training intervention. The spatial-training group received mental rotation training, whereas the active control group received literacy training in a format that matched the spatial training. Results revealed near transfer of mental rotation ability in the spatial-training group. More importantly, there was also far transfer to canonical arithmetic problems, such that children in the spatial-training group performed better on these math problems than children in the control group. Such far transfer could not be attributed to general cognitive improvement, since no improvement was observed for non-symbolic quantity processing, verbal working memory (WM), or language ability following spatial training. Spatial training may have benefitted symbolic arithmetic performance by improving visualization ability, access to the mental number line, and/or increasing the capacity of visuospatial WM.

A translation and preliminary validation of the Dutch Wound-QoL questionnaire.

BACKGROUND: Chronic wounds have a major impact on patients' health-related quality of life (HRQoL). Therefore, measuring HRQoL is an indispensable part of the treatment of patients with chronic wounds. The aim of this study was to translate and validate the Wound-QoL, a wound-specific HRQoL questionnaire, in a Dutch population. METHODS: The Wound-QoL was translated into Dutch according to the international standards. Patients with chronic wounds were asked to complete questionnaires at baseline (T0) and after six weeks (T1), including Wound-QoL, EQ-5D-3L (a generic questionnaire to measure HRQoL) and a visual analogue scale (VAS) measuring wound pain. If patients were not able to complete the questionnaire by themselves, it was read out to them by a nurse. Further data were obtained from medical records. RESULTS: Of the 120 patients included, 64 (53.3%) completed the questionnaire by themselves. To 55 patients (45.8%), the questionnaire was read out. The internal consistency of the Wound-QoL global score was high at both time points (T0: Cronbach's α = 0.89, T1: Cronbach's α = 0.92). The item selectivity for global score ranged from r = 0.25 to r = 0.77 at T0 and from r = 0.40 to r = 0.79 at T1. Overall, the self-completion and read-out subgroups showed similar internal consistency and item selectivity scores. With regard to convergent validity, significant correlations were found between Wound-QoL and EQ-5D-3L (T0: r = - 0.45, p < 0.001, T1: r = - 0.50, p < 0.001) as well as between Wound-QoL and pain VAS (T0: r = 0.23, p = 0.012, T1: r = 0.37, p = 0.001) at both time points. Responsiveness analyses showed significant correlations between changes in Wound-QoL and changes in EQ-5D-3L (r = - 0.37, p < 0.001), pain VAS (r = 0.24, p = 0.044) and wound size (r = 0.24, p = 0.013). The self-completion and read-out subgroups showed differences in convergent validity and responsiveness. CONCLUSIONS: The results indicate that the Dutch version of the Wound-QoL has positive psychometric properties. However, more research is needed to further explore the differences between self-completed and read-out questionnaires.

Canine sense of quantity: evidence for numerical ratio-dependent activation in parietotemporal cortex.

The approximate number system (ANS), which supports the rapid estimation of quantity, emerges early in human development and is widespread across species. Neural evidence from both human and non-human primates suggests the parietal cortex as a primary locus of numerical estimation, but it is unclear whether the numerical competencies observed across non-primate species are subserved by similar neural mechanisms. Moreover, because studies with non-human animals typically involve extensive training, little is known about the spontaneous numerical capacities of non-human animals. To address these questions, we examined the neural underpinnings of number perception using awake canine functional magnetic resonance imaging. Dogs passively viewed dot arrays that varied in ratio and, critically, received no task-relevant training or exposure prior to testing. We found evidence of ratio-dependent activation, which is a key feature of the ANS, in canine parietotemporal cortex in the majority of dogs tested. This finding is suggestive of a neural mechanism for quantity perception that has been conserved across mammalian evolution.

Cross-magnitude interactions across development: Longitudinal evidence for a general magnitude system.

There is general agreement that humans represent numerical, spatial, and temporal magnitudes from early in development. However, there is disagreement about whether different magnitudes converge within a general magnitude system and whether this system supports behavioral demonstrations of cross-magnitude interactions at different developmental time points. Using a longitudinal design, we found a relation between children's cross-magnitude interactions assessed at two developmental time points with different behavioral measures. More specifically, stronger cross-magnitude interactions in infancy (M = 9.3 months) predicted a stronger cross-magnitude congruity effect at preschool age (M = 44.2 months), even when controlling for performance on measures of inhibitory control, analogical reasoning, and verbal competence at preschool age. The results suggest a common mechanism for cross-magnitude interactions at different points in development as well as stability of the underlying individual differences. We argue that this mechanism reflects a nonverbal general magnitude system that is operational early in life and that displays continuity from infancy to preschool age.

Does 1 + 1 = 2nd? The relations between children's understanding of ordinal position and their arithmetic performance.

The current study examined the relations between 5- and 6-year-olds' understanding of ordinality and their mathematical competence. We focused specifically on "positional operations," a property of ordinality not contingent on magnitude, in an effort to better understand the unique contributions of position-based ordinality to math development. Our findings revealed that two types of positional operations-the ability to execute representational movement along letter sequences and the ability to update ordinal positions after item insertion or removal-predicted children's arithmetic performance. Nevertheless, these positional operations did not mediate the relation between magnitude processing (as measured by the acuity of the approximate number system) and arithmetic performance. Taken together, these findings suggest a unique role for positional ordinality in math development. We suggest that positional ordinality may aid children in their mental organization of number symbols, which may facilitate solving arithmetic computations and may support the development of novel numerical concepts.

Skeletal representations of shape in human vision: Evidence for a pruned medial axis model.

A representation of shape that is low dimensional and stable across minor disruptions is critical for object recognition. Computer vision research suggests that such a representation can be supported by the medial axis-a computational model for extracting a shape's internal skeleton. However, few studies have shown evidence of medial axis processing in humans, and even fewer have examined how the medial axis is extracted in the presence of disruptive contours. Here, we tested whether human skeletal representations of shape reflect the medial axis transform (MAT), a computation sensitive to all available contours, or a pruned medial axis, which ignores contours that may be considered "noise." Across three experiments, participants (N = 2062) were shown complete, perturbed, or illusory two-dimensional shapes on a tablet computer and were asked to tap the shapes anywhere once. When directly compared with another viable model of shape perception (based on principal axes), participants' collective responses were better fit by the medial axis, and a direct test of boundary avoidance suggested that this result was not likely because of a task-specific cognitive strategy (Experiment 1). Moreover, participants' responses reflected a pruned computation in shapes with small or large internal or external perturbations (Experiment 2) and under conditions of illusory contours (Experiment 3). These findings extend previous work by suggesting that humans extract a relatively stable medial axis of shapes. A relatively stable skeletal representation, reflected by a pruned model, may be well equipped to support real-world shape perception and object recognition.

Neural engagement with online educational videos predicts learning performance for individual students.

Online educational materials are largely disseminated through videos, and yet there is little understanding of how these videos engage students and fuel academic success. We hypothesized that components of the electroencephalogram (EEG), previously shown to reflect video engagement, would be predictive of academic performance in the context of educational videos. Two groups of subjects watched educational videos in either an intentional learning paradigm, in which they were aware of an upcoming test, or in an incidental learning paradigm, in which they were unaware that they would be tested. "Neural engagement" was quantified by the inter-subject correlation (ISC) of the EEG that was evoked by the videos. In both groups, students with higher neural engagement retained more information. Neural engagement also discriminated between attentive and inattentive video viewing. These results suggest that this EEG metric is a marker of the stimulus-related attentional mechanisms necessary to retain information. In the future, EEG may be used as a tool to design and assess online educational content.

Dynamic Influence of pH on Metalloproteinase Activity in Human Coronal and Radicular Dentin.

The aim of this study was to evaluate the effect of pH on the activation of matrix metalloproteinases (MMPs) of human coronal (CD) and radicular dentin (RD). CD and RD were pulverized to powder, and proteins were extracted with 1% phosphoric acid. The extracted proteins and the demineralized powder were separately incubated in the following solutions: 4-aminophenylmercuric acetate (control) or a buffer solution at different pHs (2.5, 4.5, 5.0, 6.0, and 7.0). After incubation, proteins were separated by electrophoresis to measure MMP activities by zymography. To assess the solubilized dentin collagen, the demineralized dentin powder was sustained in incubation buffer, and the amount of hydroxyproline (HYP) released was measured. Zymography revealed MMP-2 gelatinolytic activities for CD and RD in all experimental groups. For both substrates, the lowest pH solutions (2.5, 4.5, and 5.0) yielded higher gelatinolytic activity than those obtained by the highest pH solutions (6.0 and 7.0). For HYP analysis, no detectable absorbance values were observed for pHs of 2.5 and 4.5. The amount of HYP was higher for pH 7.0 than those of all other groups (p < 0.05), except for pH 6.0. No statistical differences were found between pHs 6.0 and 5.0 and control (p > 0.05). The MMP-2 enzyme from human CD and RD is dynamically influenced by pH: at low pH, the extracted enzyme activates this latent form, whereas collagen degradation by the matrix-bound enzyme is only observed when pHs are close to neutral.

Action ability modulates time-to-collision judgments.

Time-to-collision (TTC) underestimation has been interpreted as an adaptive response that allows observers to have more time to engage in a defensive behaviour. This bias seems, therefore, strongly linked to action preparation. There is evidence that the observer's physical fitness modulates the underestimation effect so that people who need more time to react (i.e. those with less physical fitness) show a stronger underestimation effect. Here we investigated whether this bias is influenced by the momentary action capability of the observers. In the first experiment, participants estimated the time-to-collision of threatening or non-threatening stimuli while being mildly immobilized (with a chin rest) or while standing freely. Having reduced the possibility of movement led participants to show more underestimation of the approaching stimuli. However, this effect was not stronger for threatening relative to non-threatening stimuli. The effect of the action capability found in the first experiment could be interpreted as an expansion of peripersonal space (PPS). In the second experiment, we thus investigated the generality of this effect using an established paradigm to measure the size of peripersonal space. Participants bisected lines from different distances while in the chin rest or standing freely. The results replicated the classic left-to-right gradient in lateral spatial attention with increasing viewing distance, but no effect of immobilization was found. The manipulation of the momentary action capability of the observers influenced the participants' performance in the TTC task but not in the line bisection task. These results are discussed in relation to the different functions of PPS.

Representations of numerical and non-numerical magnitude both contribute to mathematical competence in children.

A growing body of evidence suggests that non-symbolic representations of number, which humans share with nonhuman animals, are functionally related to uniquely human mathematical thought. Other research suggesting that numerical and non-numerical magnitudes not only share analog format but also form part of a general magnitude system raises questions about whether the non-symbolic basis of mathematical thinking is unique to numerical magnitude. Here we examined this issue in 5- and 6-year-old children using comparison tasks of non-symbolic number arrays and cumulative area as well as standardized tests of math competence. One set of findings revealed that scores on both magnitude comparison tasks were modulated by ratio, consistent with shared analog format. Moreover, scores on these tasks were moderately correlated, suggesting overlap in the precision of numerical and non-numerical magnitudes, as expected under a general magnitude system. Another set of findings revealed that the precision of both types of magnitude contributed shared and unique variance to the same math measures (e.g. calculation and geometry), after accounting for age and verbal competence. These findings argue against an exclusive role for non-symbolic number in supporting early mathematical understanding. Moreover, they suggest that mathematical understanding may be rooted in a general system of magnitude representation that is not specific to numerical magnitude but that also encompasses non-numerical magnitude.

Transitive inference of social dominance by human infants.

It is surprising that there are inconsistent findings of transitive inference (TI) in young infants given that non-linguistic species succeed on TI tests. To conclusively test for TI in infants, we developed a task within the social domain, with which infants are known to show sophistication. We familiarized 10- to 13-month-olds (M = 11.53 months) to a video of two dominance interactions between three puppets (bear > elephant; hippo > bear) consistent with a dominance hierarchy (hippo > bear > elephant; where '>' denotes greater dominance). Infants then viewed interactions between the two puppets that had not interacted during familiarization. These interactions were either congruent (hippo > elephant) or incongruent (elephant > hippo) with the inferred hierarchy. Consistent with TI, infants looked longer to incongruent than congruent displays. Control conditions ruled out the possibility that infants' expectations were based on stable behaviors specific to individual puppets rather than their inferred transitive dominance relations. We suggest that TI may be supported by phylogenetically ancient mechanisms of ordinal representation and visuospatial processing that come online early in human development.

Body size, body size ratio, and prey type influence the functional response of damselfly nymphs.

Predator-prey interactions play a crucial role in structuring food webs, and the functional response is one way to measure the strength of this interaction. Here, we examine how predator and prey body size affects the functional response of a generalist predator-damselfly nymphs-feeding on three prey types: copepods, Daphnia, and Chydorus. Our results suggest that consumption of copepods is independent of predator body size, while increased predator body size is associated with an increased space clearance rate for Daphnia and a reduced space clearance rate for Chydorus. When considered together, foraging rates on Daphnia and Chydorus (both cladocerans) are consistent with a hump-shaped functional response, with peak foraging rates occurring at an intermediate predator-prey size ratio. Thus, although most food web theory assumes allometric predator-prey links or peaked functional responses at intermediate predator-prey size ratios, our results suggest that both relationships may occur in food webs, in addition to size-independent functional responses.

Mandibular movements and bite force in Alzheimer's disease before and after new denture insertion.

Chewing impairment has been observed in elders with Alzheimer's disease (AD); however, it is unknown whether oral rehabilitation can improve their masticatory function. This study evaluated the influence of new removable prostheses on chewing function of patients with AD. Participants using removable dentures were divided into two groups: patients with mild AD (77·2 ± 5·8 years, n = 16) and controls (76·0 ± 4·4, n = 16). All participants received general dental treatment and new total and/or partial removable prostheses. After 2 months of adaptation to the new dentures, chewing was evaluated by the following parameters: masticatory cycle time (CT), cycle velocity (CV), and opening (OA) and closing mandibular angles (CA), registered by a kinesiographic device. Maximum bite force (MBF) was assessed using a strain sensor. Evaluations were performed at baseline and after insertion of the new prostheses. A mixed model (α = 5%) was used for within- and between-subject analyses. After insertion of new prostheses, CT was reduced, and CV and MBF were increased in both groups (P < 0·05). There were no changes in OA or CA (P > 0·05). Compared to controls, elders with AD showed higher CT and reduced MBF and CV both at baseline and after insertion of new prostheses (P < 0·05). However, OA and CA did not differ between groups (P > 0·05). Insertion of new removable prostheses improved masticatory function in elders with and without AD, but patients with mild AD still had reduced chewing parameters compared to controls.