Based on historical data pertaining to the Krummhörn population (eighteenth and nineteenth centuries, Germany), we compared reproductive histories of mothers according to whether the maternal grandmother (MGM) or the paternal grandmother (PGM) or neither of them was resident in the parents’ parish at the time of the mother’s first birth. In contrast to effects of PGMs, we discovered conditional differences in the MGM’s effects between landless people and wealthier, commercial farmers. Our data indicate that the presence of the MGM (...) only lowers the woman’s age at marriage (AAM) and her age at the birth of her first child (AFB) in the case of landless families. However, among commercial farmers, who can generally be characterized by a lower AAM and AFB, we found opposite tendencies for the MGM’s effect leading to a relatively small delay in AAM and AFB. Moreover, we also analyzed differences in the completed fertility (i.e., children ever born: CEB). Results indicate that landless families in general do have fewer CEB compared with commercial farmers except for those families in which the MGM has been present. Emphasizing that the adaptiveness of investment decisions should depend on the interaction of genetic, lineage-specific (intrinsic) and ecologically imposed (extrinsic) constraints, we conclude that kin strategies consequently address different fitness components under different conditions. (shrink)

Different housing conditions, including housing space and the physiological and social environment, may affect rodent behavior. Here, we examined the effects of different housing conditions on post-stroke angiogenesis and functional recovery to clarify the ambiguity about environmental enrichment and its components. Male rats in the model groups underwent right middle cerebral artery occlusion followed by reperfusion. The MCAO rats were divided into four groups: the physical enrichment group, the social enrichment group, the combined physical and social enrichment group and the (...) ischemia/reperfusion + standard conditioning group. The rats in the sham surgery group were housed under standard conditions. In a set of behavioral tests, including the modified Neurological Severity Score, rotarod test, and adhesive removal test, we demonstrated that the animals in the enriched condition groups exhibited significantly improved neurological functions compared to those in the standard housing group. Smaller infarction volumes were observed in the animals of the PSE group by MRI detection. The enriched conditions increased the microvessel density in the ischemic boundary zone, as revealed by CD31 immunofluorescent staining. The immunochemical and q-PCR results further showed that environmental enrichment increased the expression levels of angiogenic factors after ischemia/reperfusion injury. Our data suggest that all three enrichment conditions promoted enhanced angiogenesis and functional recovery after ischemia/reperfusion injury compared to the standard housing, while only exposure to the combination of both physical and social enrichment yielded optimal benefits. (shrink)

We investigated the effect of monetary rewards on the rate of pain discounting. Our aim, also, was to understand the effect of previous painful dental experiences on the rate of discounting pain. Two groups completed a discounting task. In the first group, delayed pain was weaker than immediate pain, and in the second group delayed pain was stronger than immediate pain. Two conditions were studied: pain was either accompanied by a monetary reward or not. We found that people preferred (...) immediate pain when it was weaker than delayed pain; however, when delayed pain was stronger than immediate pain, there was no clear preference. In both groups the preference for immediate pain was higher when pain was accompanied by a monetary reward. Previous painful experiences were not related to the rate of discounting. It was concluded that the preference for delayed pain depends on the intensity of pain, and it can be modified by rewards that accompany pain. (shrink)

Sagvolden, Johansen, Aase, and Russell (Sagvolden et al.) examine attention-deficit/hyperactivity disorder (ADHD) at levels of analysis ranging from neurotransmitters to behavior. At the behavioral level they attribute aspects of ADHD to anomalies of delay-of-reinforcement gradients. With a normal gradient, responses followed after a long delay by a reinforcer may share in the effects of that reinforcer; with a diminished or steepened gradient they may fail to do so. Steepened gradients differentially select rapidly emitted responses (hyperactivity), and they limit (...) the effectiveness with which extended stimuli become conditioned reinforcers, so that observing behavior is less well maintained (attention deficit). Impulsiveness also follows from steepened gradients, which increase the effectiveness of smaller, more immediate consequences relative to larger, more delayed ones. Individuals who vary in the degree to which their delay gradients are steepened will show different balances between hyperactivity and attention deficit. Given the range of ADHD phenomena addressed, it may be unnecessary to appeal to additional behavioral processes such as extinction deficit. Extinction deficit is more likely a derivative of attention deficit, in that failure to attend to stimuli differentially correlated with extinction should slow its progress. The account suggests how relatively small differences in delay gradients early in development might engender behavioral interactions leading to very large differences later on. The steepened gradients presumably originate in properties of neurotransmitter function, but behavioral interventions that use consistently short delays of reinforcement to build higher-order behavioral units as a scaffolding to support complex cognitive and social skills may nonetheless be feasible. Key Words: ADHD; attention deficit; delay gradient; exponential decay; extinction deficit; hyperactivity; impulsiveness; intervention; observing responses; self-control. Footnotes1000 Jeffrey Gray was the BBS Editor for this treatment. When he accepted Sagvolden et al. for publication, he invited Catania, who was one of the reviewers of the original submission, to prepare a precommentary. Com-mentators were then invited to respond to the Sagvolden et al. article, to the Catania precommentary, or to both. (shrink)

We report two studies on the effect of implicitly versus explicitly conveying affirmation and denial problems about conditionals. Recently Evans and Handley (1999) and Schroyens et al. (1999b, 2000b) showed that implicit referencing elicits matching bias: Fewer determinate inferences are made, when the categorical premise (e.g., B) mismatches the conditional's referred clause (e.g., A). Also, the effect of implicit affirmation (B affirms not-A) is larger than the effect of implicit denial (B denies A). Schroyens et al. hypothesised that this interaction (...) is due to uncertainty in the case-wise affirmation of the contrast class of negated elements involved in implicit affirmations. In Experiment 1 we tested this hypothesis by manipulating the set size of the conditional clauses. The results confirm that binary sets, where the contrast class is a singleton, eliminate the differential effect of implicit affirmation and denial. With non-binary sets the interaction is not modulated by the scope of the contrast class (3, 5, 9 elements). Experiment 2 further investigated the role of contrast classes by using class inclusion to construct implicit affirmations (Mammal vs Mammal or Monkey) and implicit denial (No-Mammal vs Mammal or Monkey), in addition to the standard implicit problems mediated by contrast-class inclusion [(No-)Mammal/No-Mammal; Reptile; Snake). Findings indicate that class inclusion (Mammal/Monkey; Reptile/ Snake) only marginally affects performance, and is independent of the type of problem. This would suggest that the implicitness problem-type interaction is dependent on constructing contrast classes. However, the experiment failed to replicate the interaction, even on the subset of problems repeating the abstract letter/number format of Experiment 1. Moreover, with the natural binary set-sizes (vowels/consonants) the implicitness effect was eliminated entirely. (shrink)

Differential equations of second order appear in physical applications such as fluid dynamics, electromagnetism, acoustic vibrations, and quantum mechanics. In this paper, necessary and sufficient conditions are established of the solutions to second-order half-linear delay differential equations of the form ς y u ′ y a ′ + ∑ j = 1 m p j y u c j ϑ j y = 0 for y ≥ y 0, under the assumption ∫ ∞ ς η − 1 (...) / a d η = ∞. We consider two cases when a c j, where a and c j are the quotient of two positive odd integers. Two examples are given to show effectiveness and applicability of the result. (shrink)

This paper deals with stochastically globally exponential stability for stochastic impulsive differential systems with discrete delays and infinite distributed delays. By using vector Lyapunov function and average dwell-time condition, we investigate the unstable impulsive dynamics and stable impulsive dynamics of the suggested system, and some novel stability criteria are obtained for SIDSs with DDs and IDDs. Moreover, our results allow the discrete delay term to be coupled with the nondelay term, and the infinite distributed delay term to (...) be coupled with the nondelay term. Finally, two examples are given to verify the effectiveness of our theories. (shrink)