Structure and stability of non-symmetric Burgers vortices

We investigate, numerically and analytically, the structure and stability of steady and quasi-steady solutions of the Navier–Stokes equations corresponding to stretched vortices embedded in a uniform non-symmetric straining field, ([alpha]x, [beta]y, [gamma]z), [alpha]+[beta]+[gamma]=0, one principal axis of extensional strain of which is aligned with the vorticity. These are known as non-symmetric Burgers vortices (Robinson & Saffman 1984). We consider vortex Reynolds numbers R=[Gamma]/(2[pi]v) where [Gamma] is the vortex circulation and v the kinematic viscosity, in the range R=1[minus sign]104, and a broad range of strain ratios [lambda]=([beta][minus sign][alpha])/([beta]+[alpha]) including [lambda]>1, and in some cases [lambda][dbl greater-than sign]1. A pseudo-spectral method is used to obtain numerical solutions corresponding to steady and quasi-steady vortex states over our whole (R, [lambda]) parameter space including [lambda] where arguments proposed by Moffatt, Kida & Ohkitani (1994) demonstrate the non-existence of strictly steady solutions. When [lambda][dbl greater-than sign]1, R[dbl greater-than sign]1 and [epsilon][identical with][lambda]/R[double less-than sign]1, we find an accurate asymptotic form for the vorticity in a region 11. An iterative technique based on the power method is used to estimate the largest eigenvalues for the non-symmetric case [lambda]>0. Stability is found for 0[less-than-or-eq, slant][lambda][less-than-or-eq, slant]1, and a neutrally convective mode of instability is found and analysed for [lambda]>1. Our general conclusion is that the generalized non-symmetric Burgers vortex is unconditionally stable to two-dimensional disturbances for all R, 0[less-than-or-eq, slant][lambda][less-than-or-eq, slant]1, and that when [lambda]>1, the vortex will decay only through exponentially slow leakage of vorticity, indicating extreme robustness in this case

Mothers make a difference: Mothers develop weaker bonds with immature sons than daughters

Among mammals, individuals form strong social bonds preferentially with their kin. Differences in these relationships are linked to differential kin availability due to sex-specific dispersal patterns, but there is some indication that differential bonding among sexes already occurs prior to maturation. However, little is known about how these patterns arise during individual development. Here we investigated sex differences in the development of mother-offspring bonds in rhesus macaques (Macaca mulatta). Our results revealed that mothers showed sex-biased bonding toward their offspring. Sons had a distinctly higher probability of receiving aggression from their mothers than did daughters in the first year of life, while no differences were found with respect to affiliative interactions. After the first year, probabilities of all affiliative and aggressive behaviours investigated were higher for daughters than for sons, although generally declining. Furthermore, sons spending less time with their mother and receiving more maternal aggression tended to disperse earlier. The results of our study suggest that mothers influence their bonding strength with offspring by interacting less affiliative with sons than daughters

Understanding potential conflicts between human and non-human-primates: A large-scale survey in Malaysia

With increasing anthropogenic pressure, interactions between humans and wildlife may become more frequent, including conflictual ones. To reduce conflicts, it is important to understand how different factors (e.g. education, previous experience, demographic vari-ables) interplay with each other and contribute to the emergence of negative attitudes and behaviours toward wildlife in humans. To address this issue, we conducted a large-scale questionnaire in Malaysia, focusing on potential conflicts between human and other pri-mates. We used generalized linear mixed models to assess how formal education, knowl-edge about primates, negative experience and potential competition affected participants’ negative attitudes to primates (i.e. how humans perceive primates), their behavioural inten-tions (i.e. opinion on how to reduce conflicts) and behaviour (i.e. measures taken to reduce negative interactions). We found that negative experience and potential competition had a negative impact on participants’ attitude and behavior (i.e. primates were more likely perceived as filthy, as negatively affecting residents’ health and safety, and as an increas-ing problem, with participants more likely to use invasive methods, including captures). Both higher education and better knowledge of primates predicted more positive behav-ioural intentions (i.e. primates should be protected, non-invasive interventions should be used). Higher education, however, was also linked to more negative attitudes (i.e. primates negatively affect residents’ health and safety), and partly to negative behavior (e.g. use of invasive methods). In contrast, better knowledge about primates predicted positive behav-iour (i.e. exclusive use of non-invasive methods). Therefore, although better knowledge of primates had no clear effect on human attitudes, it may impact on their decisions to reduce potential conflicts with wildlife, and might be the most powerful tool to mitigate conflicts between humans and other specie

A comparison between mobile and stationary gas chromatography–mass spectrometry devices for analysis of complex volatile profiles (advance online)

On-site analysis of volatile organic compounds (VOCs) with miniaturized gas chromatography–mass spectrometry (GC–MS)systems is a very rapidly developing field of application. While, on the one hand, major technological advances are improv-ing the availability of these systems on the market, on the other hand, systematic studies to assess the performance of suchinstruments are still lacking. To fill this gap, we compared three portable GC–MS devices to a state-of-the-art benchtop(stationary) system for analysis of a standard mixture of 18 VOCs. We systematically compared analytical parameters suchas the sensitivity and similarity of the signal response pattern and the quality of the obtained mass spectra. We found that theinvestigated mobile instruments (i) showed different response profiles with a generally lower number of identified analytes.Also, (ii) mass spectral reproducibility (% relative standard deviation (RSD) of the relative abundance of selective fragments)was generally worse in the mobile devices (mean RSD for all targeted fragments~9.7% vs. ~3.5% in the stationary system).Furthermore, mobile devices (iii) showed a poorer mass spectral similarity to commercial reference library spectra (>20%deviation of fragment ion relative intensity vs. ~10% in the stationary GC–MS), suggesting a less reliable identification ofanalytes by library search. Indeed, (iv) the performance was better with higher-mass and/or more abundant fragments, whichshould be considered to improve the results of library searches for substance identification. Finally, (v) the estimation ofthe signal-to-noise ratio (S/N) in mobile instruments as a measure of sensitivity revealed a significantly lower performancecompared to the benchtop lab equipment (with a ratio among medians of~8 times lower). Overall, our study reveals not only apoor signal-to-noise ratio and poor reproducibility of the data obtained from mobile instruments, but also unfavorable resultswith respect to a reliable identification of substances when they are applied for complex mixtures of volatiles

Temporal dynamics and fitness consequences of coalition formation in male primates

Coalition formation is one of the most striking forms of cooperation found in animals. Yet, there is substantial variation between taxa regarding the mechanisms by which coalitions can result in fitness consequences. Here, we investigate the influence of coalitions on dominance rank trajectories and subsequently on reproductive success in wild male crested macaques (Macaca nigra) at Tangkoko Nature Reserve (Sulawesi, Indonesia). We observed 128 coalition events involving 28 males and tested how a variety of coalition properties and factors related to the social environment influenced future male rank. We further used genetic paternity analysis of 19 infants conceived during the study to assess male reproductive success. Our results show that males participating in coalitions achieved higher-than-expected future ranks, while coalition targets had lower-than-expected future ranks. Additionally, all-up coalitions had stronger effects on rank than all-down and bridging coalitions, and these were modulated by the relative strength of coalition partners versus targets. Finally, higher ranking males were more likely to sire infants than lower ranking males. These results provide important insights regarding the mechanisms underlying coalition formation and support the idea that one major path by which coalitions can affect fitness is through influencing male dominance trajectories

Oil palm cultivation critically affects sociality in a threatened Malaysian primate

Human-induced habitat alterations globally threaten animal populations, often evoking complex behavioural responses in wildlife. This may be particularly dramatic when negatively affecting social behaviour, which fundamentally determines individual fitness and offspring survival in group-living animals. Here, we provide first evidence for significant behavioural modifications in sociality of southern pig-tailed macaques visiting Malaysian oil palm plantations in search of food despite elevated predation risk. Specifically, we found critical reductions of key positive social interactions but higher rates of aggression in the plantation interior compared to the plantation edge (i.e. plantation areas bordering the forest) and the forest. At the plantation edge, affiliation even increased compared to the forest, while central positions in the macaques' social network structure shifted from high-ranking adult females and immatures to low-ranking individuals. Further, plantations also affected mother-infant relationships, with macaque mothers being more protective in the open plantation environment. We suggest that although primates can temporarily persist in human-altered habitats, their ability to permanently adapt requires the presence of close-by forest and comes with a trade-off in sociality, potentially hampering individual fitness and infant survival. Studies like ours remain critical for understanding species’ adaptability to anthropogenic landscapes, which may ultimately contribute to facilitating their coexistence with humans and preserving biodiversity

Towards understanding multimodal traits of female reproduction in chimpanzees

Although primates have long been regarded as microsmatic, recent studies indicatethat olfaction is an important sensory mode of primate communication, for example, inthe context of reproduction. However, large gaps remain in understanding primateolfactory traits, especially in great apes. Female chimpanzees (Pan troglodytes)possess an exaggerated sexual swelling which is an imprecise signal of fertility toconfuse paternity. Even so, some high-ranking males copulating most frequently atfertile days of females seem to have more precise information on the timing ofovulation, suggesting the existence of an olfactory fertility trait. In order to provideevidence of fertility-related information in female chimpanzees, we used gaschromatography – mass spectrometry to analyze the chemical composition of femalebody odor collected across the menstrual cycle from various swelling stages (97samples of six females). We found that the chemical composition was significantlyaffected by swelling stages and detected nine substances that were strongly related toswelling stages. The existence of an additional olfactory fertility trait could either helpmales to fine-tune their sexual behavior or allow females to strengthen concealment ofthe exact timing of ovulation, which needs to be further investigated in follow-upstudies. The results of our study add much-needed evidence about the existence of anolfactory cue related to reproduction in chimpanzees and form a basis for futurestudies on the interplay between visual and olfactory information of female fertility

Olfactory inspection of female reproductive states in chimpanzees

In mammalian species, olfactory cues are important for within and between species communication. These cues can be part of multimodal signals indicating, for example, female fertility potentially perceived by male conspecifics. However, a large gap exists in our understanding of multimodal signaling in non-human catarrhines. Chimpanzees (Pan troglodytes) live in fission-fusion societies, mate promiscuously and express high levels of male-male competition. Females show a striking visual signal, an exaggerated sexual swelling, known to be a proxy of ovulation, while the maximum swelling is not matching the exact time of ovulation. The question remains if males use additional olfactory cues when being able to approach females closely. This would allow males to pinpoint the exact timing of ovulation and could be one reason why high-ranking males sire offspring more successfully than other males. Here, we present the first systematic test of such multimodal signaling by investigating male sniffing behavior directed to females in relation to their fertility in a group of 13 captive chimpanzees. Our results show that male sniffing behavior significantly increased with female swelling size, with female age as well as when fewer male competitors were present. Hence, odors might be part of a multimodal fertility cue, supporting the idea that males monitor both visual and olfactory cues to gain comprehensive information on female fertility