Applicability of a Representation for the Martin's Real-Part Formula in Model-Independent Analyses

Using a novel representation for the Martin's real-part formula without the full scaling property, an almost model-independent description of the proton-proton differential cross section data at high energies (19.4 GeV - 62.5 GeV) is obtained. In the impact parameter and eikonal frameworks, the extracted inelastic overlap function presents a peripheral effect (tail) above 2 fm and the extracted opacity function is characterized by a zero (change of sign) in the momentum transfer space, confirming results from previous model-independent analyses. Analytical parametrization for these empirical results are introduced and discussed. The importance of investigations on the inverse problems in high-energy elastic hadron scattering is stressed and the relevance of the proposed representation is commented. A short critical review on the use of Martin's formula is also presented.Comment: Two comments and one reference added at the end of Subsec. 3.3; 23 pages, 9 figures; to be published in Int. J. Mod. Phys.

Scaling violations: Connections between elastic and inelastic hadron scattering in a geometrical approach

Starting from a short range expansion of the inelastic overlap function, capable of describing quite well the elastic pp and $\bar{p}p$ scattering data, we obtain extensions to the inelastic channel, through unitarity and an impact parameter approach. Based on geometrical arguments we infer some characteristics of the elementary hadronic process and this allows an excellent description of the inclusive multiplicity distributions in $pp$ and $\bar{p}p$ collisions. With this approach we quantitatively correlate the violations of both geometrical and KNO scaling in an analytical way. The physical picture from both channels is that the geometrical evolution of the hadronic constituents is principally reponsible for the energy dependence of the physical quantities rather than the dynamical (elementary) interaction itself.Comment: 16 pages, aps-revtex, 11 figure

Formidable females and the power trajectories of socially integrated male vervet monkeys

Sexual conflict theory expects females to avoid nonoptimal mating attempts by males. Although female vervet monkeys, Chlorocebus pygerythrus, can resist direct mating attempts, higher-ranking males still have more mating opportunities than lower-ranking ones. We presume that rank-related access reflects maleemale competition that may conflict with female reproductive objectives. We extend an earlier report of codominance in this species to show that powerful females can undermine the restrictions imposed through maleemale competition by improving the dominance rank of preferred male associates. We found that the dominance hierarchies of the sexes were comprehensively interdigitated and that males who had more female spatial associates, and who groomed with well-connected females, were more likely improve their Elo-ratings, which we use as an index of male power. The effects of partner number and integration, which predicted the probability of the initiation of aggression by lower-ranking males, suggest that association with females offered the prospect of protected threat if this likelihood increased. Although female rank and aggression were not directly consequential for males, we argue that female power and influence are intertwined and that both stem from the strength of female reproductive control

Total Cross Section, Inelasticity and Multiplicity Distributions in Proton -- Proton Collisions

Multiparticle production in high energy proton -- proton collisions has been analysed in the frame of Strongly Correlated Quark Model (SCQM) of the hadron structure elaborated by the author. It is shown that inelasticity decreases at high energies and this effect together with the total cross section growth and the increasing with collision energy the masses of intermediate clusters result in the violation of KNO -- scaling.Comment: 21 pages, 11 figures, submitted to Yad. Fisik

Behavioral flexibility of vervet monkeys in response to climatic and social variability

Responses to environmental variability sheds light on how individuals are able to survive in a particular habitat and provides an indication of the scope and limits of its niche. To understand whether climate has a direct impact on activity, and determine whether vervet monkeys have the behavioral flexibility to respond to environmental change, we examined whether the amount of time spent resting and feeding in the nonmating and mating seasons were predicted by the thermal and energetic constraints of ambient temperature. Our results show that high temperatures during the nonmating season were associated with an increase in time spent resting, at the expense of feeding. Cold temperatures during the nonmating season were associated with an increase in time spent feeding, at the expense of resting. In contrast, both feeding and resting time during the mating season were independent of temperature, suggesting that animals were not adjusting their activity in relation to temperature during this period. Our data indicate that climate has a direct effect on animal activity, and that animals may be thermally and energetically compromised in the mating season. Our study animals appear to have the behavioral flexibility to tolerate current environmental variability. However, future climate change scenarios predict that the time an animal has available for behaviors critical for survival will be constrained by temperature. Further investigations, aimed at determining the degree of behavioral and physiological flexibility displayed by primates, are needed if we are to fully understand the consequences of environmental change on their distribution and survival

Individual-level movement bias leads to the formation of higher-order social structure in a mobile group of baboons

Sherpa Romeo green journal. Open access article. Creative Commons Attribution 4.0 International LIcense (CC BY 4.0) applies.In mobile social groups, influence patterns driving group movement can vary between democratic and despotic. The arrival at any single pattern of influence is thought to be underpinned by both environmental factors and group composition. To identify the specific patterns of influence driving travel decision-making in a chacma baboon troop, we used spatially explicit data to extract patterns of individual movement bias. We scaled these estimates of individual-level bias to the level of the group by constructing an influence network and assessing its emergent structural properties. Our results indicate that there is heterogeneity in movement bias: individual animals respond consistently to particular group members, and higher-ranking animals are more likely to influence the movement of others. This heterogeneity resulted in a group-level network structure that consisted of a single core and two outer shells. Here, the presence of a core suggests thatasetofhighlyinterdependentanimalsdroveroutinegroup movements. These results suggest that heterogeneity at the individual level can lead to group-level influence structures, and that movement patterns in mobile social groups can add to the exploration of both how these structures develop (i.e. mechanistic aspects) and what consequences they have for individual- and group-level outcomes (i.e. functional aspects).Ye

Mother–offspring conflict and body temperature regulation during gestation and lactation in a wild primate

1. The physiological performance of a mother during reproduction represents a trade-off between continued investment in her current offspring, and the mother's own survival and ability to invest in future offspring. Here, we used core body temperature (Tb) patterns to examine the degree to which maternal body temperatures support the infant during periods of gestation and lactation. 2. We implanted 30 wild vervet monkeys (Chlorocebus pygerythrus) with miniature data loggers to obtain continuous measurements of core Tb during periods of typical (i.e. non-drought periods) and limited (i.e. drought period) resource availability. 3. We tracked maternal Tb profiles across the gestation and lactation periods, associated with 23 births, and compared those with Tb profiles of non-reproductive females. This allowed us to examine the flexibility in maternal body temperatures and test whether limited resource availability shifts priority away from offspring investment and towards self-maintenance. 4. Vervet monkeys demonstrated the predicted pattern of gestational hypothermia and improved homeothermy in the gestation period during typical conditions, consistent with the maintenance of a thermal gradient to facilitate heat loss from the foetus. During periods of limited resource availability (i.e. drought), mothers were less homeothermic and more hyperthermic during the gestation period. 5. Vervet monkeys showed no evidence of lactational hyperthermia during typical conditions. During the drought, lactating mothers demonstrated hyperthermia and increased variability in body temperature, consistent with the increased metabolic demands and water requirements for milk production required to support growing infants. 6. Although a mother's degree of homeothermy during gestation and lactation was unrelated to her infant's chance of survival to weaning, mothers did show flexibility in the degree to which they prioritized the maintenance of a thermal environment that supports their infant's development. Together, our findings demonstrate that flexibility in a mother's investment in thermoregulation during gestation and lactation may reflect a bet-hedging trade-off between self-maintenance and offspring investment

Egalitarian despots: hierarchy steepness, reciprocity and the grooming-trade model in wild chimpanzees (Pan troglodytes)

Biological-markets theory models the action of natural selection as a marketplace in which animals are viewed as traders with commodities to offer and exchange. Studies of female Old World monkeys have suggested that grooming might be employed as a commodity to be reciprocated or traded for alternative services, yet previous tests of this grooming-trade model in wild adult male chimpanzees (Pan troglodytes) have yielded mixed results. Here we provide the strongest test of the model to date for male chimpanzees: we use data drawn from two social groups (communities) of chimpanzees from different populations, and give explicit consideration to variation in dominance hierarchy steepness as such variation results in differing conditions for biological markets. First, analysis of data from published accounts of other chimpanzee communities, together with our own data, showed that hierarchy steepness varied considerably within and across communities and that the number of adult males in a community aged 20-30 years predicted hierarchy steepness. The two communities in which we tested predictions of the grooming-trade model lay at opposite extremes of this distribution. Second, in accord with the grooming-trade model, we found evidence that male chimpanzees trade grooming for agonistic support where hierarchies are steep (despotic) and consequent effective support is a rank-related commodity, but not where hierarchies are shallow (egalitarian). However, we also found that grooming was reciprocated regardless of hierarchy steepness. Our findings also hint at the possibility of agonistic competition, or at least exclusion, in relation to grooming opportunities compromising the free market envisioned by Biological Markets theory. Our results build on previous findings across chimpanzee communities to emphasise the importance of reciprocal grooming exchanges among adult male chimpanzees, which can be understood in a biological markets framework if grooming by or with particular individuals is a valuable commodity

The thermal consequences of primate birth hour and its evolutionary implications

Most primates, including humans, give birth during the inactive phase of the daily cycle. Practical constraints therefore limit our knowledge of the precise timing of nocturnal birth in wild diurnal primates and so limit our understanding of selective pressures and consequences. We measured maternal core body temperature (T b) across 24 births in a population of wild vervet monkeys using biologgers. We identified distinct perturbations in T b during the birth period, including declining T b during labour and the rapid recovery of T b post-parturition. Vervet monkeys typically gave birth during their inactive phase in synchrony with the nadir of the maternal nychthemeral T b rhythm but also showed remarkable inter-individual variability in their absolute T b during birth. Our findings support the view that selection may have favoured a nocturnal timing of primate birth to coincide with lower night-time T b and environmental temperatures, which improve thermal efficiency during birth