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SUMMARY Asymmetric structures experience uneven deformation demand among different resisting planes and stories when subjected to earthquake excitation. Damage is focused in some elements jeopardizing structural integrity. These structures are common in professional practice because of architectural and functionality constraints. In this scenario the use of energy dissipation devices (EDD) has arisen as an advisable solution to balance and minimize structural damage. Procedures for the design of linear structures equipped with EDD have been widely proposed in the literature, few of them deal with the optimum spatial distribution of nonlinear systems. This paper evaluates and compares the optimized spatial damper distribution of linear and nonlinear systems. An optimization technique is presented based on control indexes called min–max algorithm. Then, this technique is compared with two simple methodologies: (i) the fully stressed design, which is an analysis‐redesign procedure, and (ii) the simplified sequential search algorithm (SSSA), which is a sequential method. It is pointed out that the SSSA is a fixed step coordinate descent type method. The examples considered show that the SSSA is a discrete approximation of the min–max algorithm, not only for linear but also for nonlinear structures equipped with linear and nonlinear EDD. Furthermore, it is found that the distribution of EDD obtained from a linear analysis is a good approximation of the nonlinear optimal solution. The SSSA is a reliable method that can be applied to achieve drift and torsional balance for design purposes; moreover, it can be implemented with conventional tools available in professional practice. Copyright © 2012 John Wiley & Sons, Ltd.

Maternal behavior in the rabbit is restricted to a brief nursing period every day. Previously we demonstrated that this event induces daily rhythms of PER1 protein, the product of the clock gene Per1, in oxytocinergic and dopaminergic populations in the hypothalamus of lactating rabbit does. This is significant for the periodic production and ejection of milk, but the activation of other areas of the brain has not been explored. Here we hypothesized that daily suckling will induce a rhythm in the preoptic area, lateral septum and bed nucleus of the stria terminalis, which are important areas for the expression of maternal behavior in mammals including the rabbit. To this end, we analyzed PER1 expression in those areas through a complete 24-h cycle at lactation day 7. Does were scheduled to nurse during either the day at 10:00 (ZT03) or the night at 02:00 (ZT19) h. Non-pregnant, non-lactating females were used as controls. In contrast to control females, lactating does show a clear, significant rhythm of PER1 that shifts in parallel to timing of nursing in the preoptic area and lateral septum. We determined that the maximal expression of PER1 at 8 h after scheduled nursing decreased significantly at 24 and 48 h after the absence of suckling. This effect was more pronounced in the lateral septum than in the preoptic area. We conclude that daily suckling is a powerful stimulus that induces rhythmic activity in brain structures in the rabbit that appear to be part of a maternal entrainable circuit.

Maternal care is a motivated behavior and in the rabbit it is restricted to the spontaneous return of the mother to nurse her pups for just a few minutes once a day. Previously we have reported neural activation of brain areas and neuroendocrine cells after nursing. However, this daily spontaneous return suggests that the mother is in a high motivational state to nurse her pups. Here we hypothesized that during anticipation of nursing there is an activation of dopaminergic neurons of the mesolimbic system and in their target areas. Then we explored, by the expression of FOS protein, possible activation of the mesolimbic system as well as dopaminergic cells of the A10 cell group before and after nursing and in control does. Additionally, we measured FOS expression in the preoptic area and lateral septum. We found a significant increase of FOS before nursing, and a further increase after nursing, in the mesolimbic system and dopaminergic cells as well as in the preoptic area and lateral septum. Interestingly, the medial prefrontal area shows an intense activation during anticipation of nursing, which remains after nursing. We conclude that the activation of the mesolimbic system before nursing is related to the high locomotor behavior prior to the next nursing bout and support the proposal that the mother is in a high motivational state at the time of returning to the nest. The additional activation after nursing can be related to the neuroendocrine and neural consequences of the milk ejection reflex by suckling.

Background Major depressive episodes (MDEs) show diverse cortisol level alterations. Heterogeneity in symptom profiles, symptom severity and cortisol specimens may explain these heterogeneous results. Less severely ill out-patients with a non-melancholic MDE (NM-MDE) may have a variation in the rhythm of cortisol secretion rather than in its concentration. Method Cortisol measures were taken (a) over a short-term period (12 h) by measuring daily salivary output using the area under the curve with respect to the ground (AUCg) and (b) over a long-term period (3 months) in hair. Additionally, cortisol reactivity measures in saliva – the cortisol awakening response and the 30 min delta cortisol secretion after awakening (DELTA) – were investigated in 19 patients with a melancholic MDE (M-MDE) and 52 with a NM-MDE, and in 40 matched controls who were recruited from the UK and Chile. Depression severity scores were correlated with different cortisol measures. Results The NM-MDE group showed a decreased AUCg in comparison with controls (P = 0.02), but normal cortisol reactivity and long-term cortisol levels. The M-MDE group did not exhibit any significant cortisol alterations nor an association with depression severity scores. Higher Hamilton Rating Scale for Depression score was linked with decreased hair cortisol concentration (HCC, P = 0.05) and higher DELTA (P = 0.04) in NM-MDEs, whereas decreased HCC was the sole alteration associated with out-patients with severe M-MDEs. Conclusions The contrasting short- and long-term cortisol output results are compatible with an alteration in the rhythm of cortisol secretion in NM-MDEs. This alteration may consist of large and/or intense episodes of hypercortisolaemia in moderate NM-MDEs and frequent, but brief and sharp early-morning DELTAs in its severe form. These changes may reflect the effects of environmental factors or episodes of nocturnal hypercortisolaemia that were not measured by the short-term samples used in this study.