How Reliable are Density Estimates for Diurnal Primates?

Primate population assessments provide the basis for comparative studies and are necessary prerequisites in determining conservation status. The most widely used assessment method is line transect sampling, which generates systematic data quickly and comparatively inexpensively. In contrast, the presumably most reliable method is long-term monitoring of known groups, which is both slow and costly. To assess the reliability of various analytical methods, we compared group and population densities for white-handed gibbons (Hylobates lar carpenteri) and Phayre’s leaf monkeys (Trachypithecus phayrei crepusculus) derived from transect walks with those from long-term group follows at Phu Khieo Wildlife Sanctuary, Thailand. Our assistants and we regularly walked a 4-km transect over 30 mo (480 km total), resulting in 155 gibbon sightings and 125 leaf monkey sightings. We then estimated densities via 1) DISTANCE and 2) the Kelker method based on perpendicular distances (PD) or animal-to-observer distances (AOD). We compared the 3 estimates to values based on known home ranges (95% kernels), accounting for home range overlap, combined with group size data. Analyses of line transect data consistently overestimated group densities for both species, while underestimating group size for leaf monkeys. Quality of results varied according to the group size and spread of each species. However, we found, in accordance with previous studies, that values derived via AOD (or its derivations) matched most closely with population estimates based on home range data.     

How Does the Crayfish Swimmeret System Work? Insights from Nearest-Neighbor Coupled Oscillator Models

Rhythmic movements of crayfish swimmerets are coordinated by a neural circuit that links their four abdominal ganglia. Each swimmeret is driven by its own small local circuit, or pattern-generating module. We modeled this networkas a chain of four oscillators, bidirectionally coupled to their nearest neighbors, and tested the models ability to reproduce experimentally observed changes in intersegmental phases and in period caused by differential excitation of selected abdominal ganglia. The choices needed to match the experimental data lead to the followingpredictions: coupling between ganglia is asymmetric; the ascending and descending coupling have approximately equal strengths; intersegmental coupling does not significantly affect the frequency of the system; and excitation affects the intrinsic frequencies of the oscillators and might also change properties ofintersegmental coupling.     

Re-Evaluating Neonatal-Age Models for Ungulates: Does Model Choice Affect Survival Estimates?

New-hoof growth is regarded as the most reliable metric for predicting age of newborn ungulates, but variation in estimated age among hoof-growth equations that have been developed may affect estimates of survival in staggered-entry models. We used known-age newborns to evaluate variation in age estimates among existing hoof-growth equations and to determine the consequences of that variation on survival estimates. During 2001–2009, we captured and radiocollared 174 newborn (≤24-hrs old) ungulates: 76 white-tailed deer (Odocoileus virginianus) in Minnesota and South Dakota, 61 mule deer (O. hemionus) in California, and 37 pronghorn (Antilocapra americana) in South Dakota. Estimated age of known-age newborns differed among hoof-growth models and varied by >15 days for white-tailed deer, >20 days for mule deer, and >10 days for pronghorn. Accuracy (i.e., the proportion of neonates assigned to the correct age) in aging newborns using published equations ranged from 0.0% to 39.4% in white-tailed deer, 0.0% to 3.3% in mule deer, and was 0.0% for pronghorns. Results of survival modeling indicated that variability in estimates of age-at-capture affected short-term estimates of survival (i.e., 30 days) for white-tailed deer and mule deer, and survival estimates over a longer time frame (i.e., 120 days) for mule deer. Conversely, survival estimates for pronghorn were not affected by estimates of age. Our analyses indicate that modeling survival in daily intervals is too fine a temporal scale when age-at-capture is unknown given the potential inaccuracies among equations used to estimate age of neonates. Instead, weekly survival intervals are more appropriate because most models accurately predicted ages within 1 week of the known age. Variation among results of neonatal-age models on short- and long-term estimates of survival for known-age young emphasizes the importance of selecting an appropriate hoof-growth equation and appropriately defining intervals (i.e., weekly versus daily) for estimating survival.     

How Does Dog-Walking Influence Perceptions of Health and Wellbeing in Healthy Adults? A Qualitative Dog-Walk-Along Study

The aim of this study was to explore perceptions of health and wellbeing related to dog-walking in healthy adults. Ten self-reported healthy adult dog-walkers took part in one dog-walk-along interview, and nine of the 10 participants also attended one follow-up participatory analysis session. All interviews took place within the metropolitan area of Dunedin, Aotearoa/New Zealand. Dog-walk-along interviews were participant-led, audio and video recorded, and transcribed. Participants’ input into the inductive generation of themes was sought during the follow-up participatory analysis session. Three themes were identified: participants had an “Emotional Connection” with their dog(s); dog-walking led to “Healthy Interactions” (social and environmental interactions); and participants had come to value dog-walking for its aggregate benefits for Psychological Wellbeing. Our dog-walk-along interviews have revealed novel insights about how the emotional connection between human and dog strengthens intrinsic motivation to exercise (through dog-walking) whilst concurrently enhancing human psychological wellbeing through the act of giving something that gives pleasure to the dog. Through the combined methods of dog-walk-along interviews and participatory analysis sessions, we were able to identify negative influences on human psychological well-being that included anxiety about both dog behaviors and social encounters with other humans. Positive and negative aspects of dog-walking that we identified can be used by health promotion advocates to refine dog-walking related advice, programs, and initiatives.     

Meta-Analysis of the INSIG2 Association with Obesity Including 74,345 Individuals: Does Heterogeneity of Estimates Relate to Study Design?

The INSIG2 rs7566605 polymorphism was identified for obesity (BMI≥30 kg/m²) in one of the first genome-wide association studies, but replications were inconsistent. We collected statistics from 34 studies (n = 74,345), including general population (GP) studies, population-based studies with subjects selected for conditions related to a better health status (‘healthy population’, HP), and obesity studies (OB). We tested five hypotheses to explore potential sources of heterogeneity. The meta-analysis of 27 studies on Caucasian adults (n = 66,213) combining the different study designs did not support overall association of the CC-genotype with obesity, yielding an odds ratio (OR) of 1.05 (p-value = 0.27). The I² measure of 41% (p-value = 0.015) indicated between-study heterogeneity. Restricting to GP studies resulted in a declined I² measure of 11% (p-value = 0.33) and an OR of 1.10 (p-value = 0.015). Regarding the five hypotheses, our data showed (a) some difference between GP and HP studies (p-value = 0.012) and (b) an association in extreme comparisons (BMI≥32.5, 35.0, 37.5, 40.0 kg/m² versus BMI<25 kg/m²) yielding ORs of 1.16, 1.18, 1.22, or 1.27 (p-values 0.001 to 0.003), which was also underscored by significantly increased CC-genotype frequencies across BMI categories (10.4% to 12.5%, p-value for trend = 0.0002). We did not find evidence for differential ORs (c) among studies with higher than average obesity prevalence compared to lower, (d) among studies with BMI assessment after the year 2000 compared to those before, or (e) among studies from older populations compared to younger. Analysis of non-Caucasian adults (n = 4889) or children (n = 3243) yielded ORs of 1.01 (p-value = 0.94) or 1.15 (p-value = 0.22), respectively. There was no evidence for overall association of the rs7566605 polymorphism with obesity. Our data suggested an association with extreme degrees of obesity, and consequently heterogeneous effects from different study designs may mask an underlying association when unaccounted for. The importance of study design might be under-recognized in gene discovery and association replication so far.     

Does Celiac Disease Influence Survival in Sepsis? A Nationwide Longitudinal Study

BackgroundIndividuals with celiac disease (CD) are at increased risk of sepsis. The aim of this study was to examine whether CD influences survival in sepsis of bacterial origin.MethodsNationwide longitudinal registry-based study. Through data on small intestinal biopsies from Sweden’s 28 pathology departments, we identified 29,096 individuals with CD (villous atrophy, Marsh stage III). Each individual with CD was matched with five population-based controls. Among these, 5,470 had a record of sepsis according to the Swedish Patient Register (1,432 celiac individuals and 4,038 controls). Finally we retrieved data on mortality in sepsis patients through the Swedish Cause of Death Registry.ResultsCD was associated with a 19% increase in overall mortality after sepsis (95% confidence interval (CI) = 1.09–1.29), with the highest relative risk occurring in children (adjusted hazard ratio (aHR) = 1.62; 95%CI = 0.67–3.91). However, aHR for death from sepsis was lower (aHR = 1.10) and failed to reach statistical significance (95%CI = 0.72–1.69). CD did not influence survival within 28 days after sepsis (aHR = 0.98; 95%CI = 0.80–1.19).ConclusionsAlthough individuals with CD seem to be at an increased risk of overall death after sepsis, that excess risk does not differ from the general excess mortality previously seen in celiac patients in Sweden. CD as such does not seem to influence short-term or sepsis-specific survival in individuals with sepsis and therefore is not an independent risk factor for poor prognosis in sepsis.     

How Far Does a Receptor Influence Vibrational Properties of an Odorant?

The biophysical mechanism of the sense of smell, or olfaction, is still highly debated. The mainstream explanation argues for a shape-based recognition of odorant molecules by olfactory receptors, while recent investigations suggest the primary olfactory event to be triggered by a vibrationally-assisted electron transfer reaction. We consider this controversy by studying the influence of a receptor on the vibrational properties of an odorant in atomistic details as the coupling between electronic degrees of freedom of the receptor and the vibrations of the odorant is the key parameter of the vibrationally-assisted electron transfer. Through molecular dynamics simulations we elucidate the binding specificity of a receptor towards acetophenone odorant. The vibrational properties of acetophenone inside the receptor are then studied by the polarizable embedding density functional theory approach, allowing to quantify protein-odorant interactions. Finally, we judge whether the effects of the protein provide any indications towards the existing theories of olfaction.     

Does the Type of Event Influence How User Interactions Evolve on Twitter?

The number of people using on-line social networks as a new way of communication is continually increasing. The messages that a user writes in these networks and his/her interactions with other users leave a digital trace that is recorded. Thanks to this fact and the use of network theory, the analysis of messages, user interactions, and the complex structures that emerge is greatly facilitated. In addition, information generated in on-line social networks is labeled temporarily, which makes it possible to go a step further analyzing the dynamics of the interaction patterns. In this article, we present an analysis of the evolution of user interactions that take place in television, socio-political, conference, and keynote events on Twitter. Interactions have been modeled as networks that are annotated with the time markers. We study changes in the structural properties at both the network level and the node level. As a result of this analysis, we have detected patterns of network evolution and common structural features as well as differences among the events.     

How Small is too Small? Camera Trap Survey Areas and Density Estimates for Ocelots in the Bolivian Chaco

Studies on carnivores, which are generally difficult to observe directly because they are elusive and nocturnal, are carried out through indirect methods, e.g. , camera trapping and radiotracking. The first method has been used to estimate population densities of species that can be differentiated as individuals using unique pelage patterns. However, the use of capture–recapture methodology has raised doubts regarding the estimation of the sampling area around the camera traps, which is obtained using maximum distances traveled by individuals photographed at two or more different locations. In this paper, the results from camera traps are compared with a radiotracking study carried out simultaneously with ocelots ( Leopardus pardalis ) to confirm whether maximum distances observed in camera traps coincide with ranging patterns determined from radio telemetry, and in turn whether the sampling areas estimated from camera traps are appropriate for estimating density. Mean maximum distance moved was 2880 m according to camera trap records during a 60-d survey period while, with radiotracking, the maximum distance moved was 3176 m during the same period. The difference is not significant, and the sampling areas estimated with camera traps to assess ocelot density are reliable. However, if the area covered by cameras is reduced to less than three to four times average home range for the target species, then density estimates from camera trapping are exaggerated because of the reduced observed distances and the fact that multiple individuals can overlap in relatively small areas.     

Spatial Models of Prebiotic Evolution: Soup Before Pizza?

The problem of information integration andresistance to the invasion of parasitic mutants in prebiotic replicator systemsis a notorious issue of research on the origin of life.Almost all theoretical studies published so far havedemonstrated that some kind of spatial structure is indispensable forthe persistence and/or the parasite resistance of any feasible replicator system.Based on a detailed critical survey of spatial models on prebiotic informationintegration, we suggest a possible scenario for replicator system evolution leadingto the emergence of the first protocells capable of independent life.We show that even the spatial versions of the hypercycle model are vulnerable toselfish parasites in heterogeneous habitats. Contrary, the metabolic system remainspersistent and coexistent with its parasites both on heterogeneous surfaces andin chaotically mixing flowing media. Persistent metabolic parasites can beconverted to metabolic cooperators, or they can gradually obtain replicase activity.Our simulations show that, once replicase activity emerged, a gradual and simultaneousevolutionary improvement of replicase functionality (speed and fidelity) andtemplate efficiency is possible only on a surface that constrains the mobility ofmacromolecule replicators. Based on the results of the models reviewed, we suggestthat open chaotic flows (`soup') and surface dynamics (`pizza') both played keyroles in the sequence of evolutionary events ultimately concluding in theappearance of the first living cell on Earth.     

Does Syntactic Alignment Effectively Influence How Speakers Are Perceived by Their Conversation Partner?

The way we talk can influence how we are perceived by others. Whereas previous studies have started to explore the influence of social goals on syntactic alignment, in the current study, we additionally investigated whether syntactic alignment effectively influences conversation partners’ perception of the speaker. To this end, we developed a novel paradigm in which we can measure the effect of social goals on the strength of syntactic alignment for one participant (primed participant), while simultaneously obtaining usable social opinions about them from their conversation partner (the evaluator). In Study 1, participants’ desire to be rated favorably by their partner was manipulated by assigning pairs to a Control (i.e., primed participants did not know they were being evaluated) or Evaluation context (i.e., primed participants knew they were being evaluated). Surprisingly, results showed no significant difference in the strength with which primed participants aligned their syntactic choices with their partners’ choices. In a follow-up study, we used a Directed Evaluation context (i.e., primed participants knew they were being evaluated and were explicitly instructed to make a positive impression). However, again, there was no evidence supporting the hypothesis that participants’ desire to impress their partner influences syntactic alignment. With respect to the influence of syntactic alignment on perceived likeability by the evaluator, a negative relationship was reported in Study 1: the more primed participants aligned their syntactic choices with their partner, the more that partner decreased their likeability rating after the experiment. However, this effect was not replicated in the Directed Evaluation context of Study 2. In other words, our results do not support the conclusion that speakers’ desire to be liked affects how much they align their syntactic choices with their partner, nor is there convincing evidence that there is a reliable relationship between syntactic alignment and perceived likeability.     

Does Spatial Locative Comprehension Predict Landmark-Based Navigation?

In the present study we investigated the role of spatial locative comprehension in learning and retrieving pathways when landmarks were available and when they were absent in a sample of typically developing 6- to 11-year-old children. Our results show that the more proficient children are in understanding spatial locatives the more they are able to learn pathways, retrieve them after a delay and represent them on a map when landmarks are present in the environment. These findings suggest that spatial language is crucial when individuals rely on sequences of landmarks to drive their navigation towards a given goal but that it is not involved when navigational representations based on the geometrical shape of the environment or the coding of body movements are sufficient for memorizing and recalling short pathways.     

SCO Trimers as High-energy Materials? A Density Functional Study

Density functional calculations using the hybrid B3LYP functional have been carried out on the fragmentation reaction of cyclic SCO trimers. Analogous calculations for CO₂ and HNCO have also been performed for comparison. The energies of the different trimers relative to those of the isolated monomers as well as the energy barriers to fragmentation have been calculated. For all the calculations, a reaction path in which three bonds are simultaneously broken has been considered. It has been found that the fragmentation of cyclic SCO trimers is a rather facile process. The same statement applies to the cyclic CO₂ trimer but not to the HNCO one. In addition, the latter is much more stable than three free HNCO monomers, which is not the case for SCO and CO₂.