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Social relationships can have important fitness consequences. Although there is increasing evidence that social relationships carry over across contexts, few studies have investigated whether relationships formed early in life are carried over to adulthood. For example, juveniles of monogamous species go through a major life history stage transition, pair formation, during which the pair bond becomes a central unit of the social organization. At present, it remains unclear whether pair members retain their early life relationships after pair formation. We investigated whether same-sex associations formed early in life carry over into adulthood and whether carryover was dependent on season, in a monogamous species. We also investigated the role of familiarity, genetic relatedness and aggression on the perseverance of social associations. We studied the social structure before and after pair formation in captive barnacle geese, Branta leucopsis, a highly social, long-lived, monogamous species. We constructed association networks of groups of geese before pair formation, during the subsequent breeding season and in the following wintering season. Next, we studied how these associations carried over during seasonal changes. We found that early life associations in females were lost during the breeding season but resurfaced during the subsequent wintering season. In males, the early life associations persisted across both seasons. Association persistence was not mediated by genetic relatedness or familiarity. The high level of aggressiveness of males, but not females, in the breeding season suggests that males may have played a key role in shaping both their own social environment and that of their partners. We show that early life social relationships can be maintained well into later life. Such relationships can be sustained even if they are temporarily disrupted, for example due to reproductive behaviour. Our findings therefore highlight that the early life social env

A considerable body of research within the interaction framework (Long, 1996) has centred on the language-related episodes (LREs) which occur when learners topicalize a specific linguistic item while they are engaged in meaning-focused tasks. Several studies have shown that the production of LREs may be influenced by the proficiency level of the learners (Kim & McDonough, 2008; Leeser, 2004). Sociocultural theory (Lantolf & Appel, 1994) has also explored collaborative work and the effect that pairing learners with the same proficiency levels or different patterns of interaction (Storch, 2002) has on the production of LREs (e.g., Mozaffari, 2017; Storch & Aldosari 2013), but little research has compared the effect of the pair formation method (student-selected vs. proficiency-matched) on young learners’ production of LREs and pair dynamics. This study compares young CLIL learners (aged 10-12) in student-selected and proficiency-matched pairs in task-based interaction. Results indicate that learners produce more meaning-based than form-based LREs, regardless of their pair formation method. The percentage of meaning-based LREs which are resolved accurately is much higher in proficiency-matched dyads than in student-selected ones. As for the patterns of interaction (Storch, 2002), the dynamics of proficiency-matched dyads are of a more collaborative nature than those of self-selected pairs.

Year-round behavioral observations and surveys were used to investigate the temporal dynamics of life history events and associated variation in behavioral activities of the endangered, island-endemic Hawaiian Duck (Anas wyvilliana) on Kaua‘i, Hawai‘i, USA. Although breeding activity occurred throughout the year, backdated brood observations (n = 67) revealed that birds initiated 94% of nests during the 9-month period from September through May, their peak nesting season. A greater proportion of females (n = 149) were paired during the peak nesting season (75%) than the off-peak season (48%). Behavioral patterns (n = 984; 329 hr) differed between seasons for males but not for females. Males allocated more time to vigilance and less time to foraging during the peak nesting season than the off-peak season. Activity budgets also differed between sexes, but only during the peak nesting season. During this period, females spent more time foraging than males, whereas males allocated more time to vigilance, locomotion, and social activities. Current management objectives for the Hawaiian Duck aim to provide resources for multiple life history stages concurrently throughout the year, and although this approach is largely appropriate, our results suggest refinements in the timing of certain activities (e.g., managing nesting habitat to be available during September-May).

Initial mate choice and re-mating strategies (infidelity and divorce) influence individual fitness. Both of these should be influenced by the social environment, which determines the number and availability of potential partners. While most studies looking at this relationship take a population-level approach, individual-level responses to variation in the social environment remain largely unstudied. Here, we explore carry-over effects on future mating decisions of the social environment in which the initial mating decision occurred. Using detailed data on the winter social networks of great tits, we tested whether the probability of subsequent divorce, a year later, could be predicted by measures of the social environment at the time of pairing. We found that males that had a lower proportion of female associates, and whose partner ranked lower among these, as well as inexperienced breeders, were more likely to divorce after breeding. We found no evidence that a female’s social environment influenced the probability of divorce. Our findings highlight the importance of the social environment that individuals experience during initial pair formation on later pairing outcomes, and demonstrate that such effects can be delayed. Exploring these extended effects of the social environment can yield valuable insights into processes and selective pressures acting upon the mating strategies that individuals adopt.

We report membership change in a group of wild agile gibbons, Hylobates agilis agilis, in West Sumatra, Indonesia. During 6-month observational periods, we focused on a particular unit of individuals known as the B group. We confirmed that the group consisted of five individuals: one adult female, one adult male, one subadult male, one subadult female, and one infant male. During our observations, the resident adult male and the two subadult individuals dispersed or disappeared, and a new adult male took over the group. We examined the effects of the male replacement on the territorial boundary, using the auditory census technique. The boundary was stable. We also documented the succession of the home range. Our results indicate a flexible social structure in this species and contribute some useful data to an ongoing debate on their social dynamics.

The direct mechanism of dissociative recombination of HF+ is studied using both time-dependent and time-independent methods, where the dynamics on 30 resonant states is explored. The relevant electronic states are calculated ab initio, by combining electron scattering calculations with multireference configuration interaction structure calculations. For collision energies between 0.04 and 10 eV, we obtain qualitative agreement with experiment. At 1.9 eV there is a sharp threshold in both the experimental and theoretical cross sections that can be explained by the opening of new asymptotic limits. The measured cross section below 0.04 eV is not reproduced due to the neglect of the electronic couplings between the neutral states. We examine the validity of the local approximation for treating autoionization from the resonant states included in this study., Uppdaterad från manuskript till artikel: 20101103.QC 20101103

Models of an individual photon having joint wave-particle properties, needle-like geometry, and spin cannot be based on conventional theory, but be deduced in terms of a revised quantum electrodynamic approach. In this paper the latter is applied to two-slit configurations and electron-positron pair formation: (a) Two-slit experiments performed earlier by Tsuchiya et al. and recently by Afshar et al. demonstrate the joint wave-particle properties of the individual photon, and agree with Einstein's argument against Complementarity. The present theory is consistent with these results. (b) The elementary electron-positron pair formation process is considered, with special attention to the involved orbits, conservation of energy, spin, and electric charge. The obtained model appears to be consistent with the process in which the created electron and positron move along two rays and have original directions along the path of the incoming photon. The nonzero electric field divergence of the theory is associated with all intrinsic local electric charge density. This may explain that the photon call decay oil account of the impact from all external electric field.

We explore the transmission process for sexually transmitted diseases (STDs). We derive the classical frequency-dependent incidence mechanistically from a pair-formation model, using an approximation that applies to populations with rapid pairing dynamics (such as core groups or non-pair-bonding animals). This mechanistic derivation provides a framework to assess how accurately frequency-dependent incidence portrays the pair-based transmission known to underlie STD dynamics. This accuracy depends strongly on the disease being studied: frequency-dependent formulations are more suitable for chronic less-transmissible infections than for transient highly transmissible infections. Our results thus support earlier proposals to divide STDs into these two functional classes, and we suggest guidelines to help assess under what conditions each class can be appropriately modelled using frequency-dependent incidence. We then extend the derivation to include situations where infected individuals exhibit altered pairing behaviour. For four cases of increasing behavioural complexity, analytic expressions are presented for the generalized frequency-dependent incidence rate, basic reproductive number (R0) and steady-state prevalence (i∞) of an epidemic. The expression for R0is identical for all cases, giving refined insights into determinants of invasibility of STDs. Potentially significant effects of infection-induced changes in contact behaviour are illustrated by simulating epidemics of bacterial and viral STDs. We discuss the application of our results to STDs (in humans and animals) and other infectious diseases.

We explore the transmission process for sexually transmitted diseases (STDs). We derive the classical frequency-dependent incidence mechanistically from a pair-formation model, using an approximation that applies to populations with rapid pairing dynamics (such as core groups or non-pair-bonding animals). This mechanistic derivation provides a framework to assess how accurately frequency-dependent incidence portrays the pair-based transmission known to underlie STD dynamics. This accuracy depends strongly on the disease being studied: frequency-dependent formulations are more suitable for chronic less-transmissible infections than for transient highly transmissible infections. Our results thus support earlier proposals to divide STDs into these two functional classes, and we suggest guidelines to help assess under what conditions each class can be appropriately modelled using frequency-dependent incidence. We then extend the derivation to include situations where infected individuals exhibit altered pairing behaviour. For four cases of increasing behavioural complexity, analytic expressions are presented for the generalized frequency-dependent incidence rate, basic reproductive number (R-0) and steady-state prevalence (i(infinity)) of an epidemic. The expression for R-0 is identical for all cases, giving refined insights into determinants of invasibility of STDs. Potentially significant effects of infection-induced changes in contact behaviour are illustrated by simulating epidemics of bacterial and viral STDs. We discuss the application of our results to STDs (in humans and animals) and other infectious diseases.

We explore the transmission process for sexually transmitted diseases (STDs). We derive the classical frequency-dependent incidence mechanistically from a pair-formation model, using an approximation that applies to populations with rapid pairing dynamics (such as core groups or non-pair-bonding animals). This mechanistic derivation provides a framework to assess how accurately frequency-dependent incidence portrays the pair-based transmission known to underlie STD dynamics. This accuracy depends strongly on the disease being studied: frequency-dependent formulations are more suitable for chronic less-transmissible infections than for transient highly transmissible infections. Our results thus support earlier proposals to divide STDs into these two functional classes, and we suggest guidelines to help assess under what conditions each class can be appropriately modelled using frequency-dependent incidence. We then extend the derivation to include situations where infected individuals exhibit altered pairing behaviour. For four cases of increasing behavioural complexity, analytic expressions are presented for the generalized frequency-dependent incidence rate, basic reproductive number (R-0) and steady-state prevalence (i(infinity)) of an epidemic. The expression for R-0 is identical for all cases, giving refined insights into determinants of invasibility of STDs. Potentially significant effects of infection-induced changes in contact behaviour are illustrated by simulating epidemics of bacterial and viral STDs. We discuss the application of our results to STDs (in humans and animals) and other infectious diseases.

We explore the transmission process for sexually transmitted diseases (STDs). We derive the classical frequency-dependent incidence mechanistically from a pair-formation model, using an approximation that applies to populations with rapid pairing dynamics (such as core groups or non-pair-bonding animals). This mechanistic derivation provides a framework to assess how accurately frequency-dependent incidence portrays the pair-based transmission known to underlie STD dynamics. This accuracy depends strongly on the disease being studied: frequency-dependent formulations are more suitable for chronic less-transmissible infections than for transient highly transmissible infections. Our results thus support earlier proposals to divide STDs into these two functional classes, and we suggest guidelines to help assess under what conditions each class can be appropriately modelled using frequency-dependent incidence. We then extend the derivation to include situations where infected individuals exhibit altered pairing behaviour. For four cases of increasing behavioural complexity, analytic expressions are presented for the generalized frequency-dependent incidence rate, basic reproductive number (R0) and steady-state prevalence (i∞) of an epidemic. The expression for R0is identical for all cases, giving refined insights into determinants of invasibility of STDs. Potentially significant effects of infection-induced changes in contact behaviour are illustrated by simulating epidemics of bacterial and viral STDs. We discuss the application of our results to STDs (in humans and animals) and other infectious diseases.