Relation Between First Arrival Time and Permeability in Self-Affine Fractures with Areas in Contact

We demonstrate that the first arrival time in dispersive processes in self-affine fractures are governed by the same length scale characterizing the fractures as that which controls their permeability. In one-dimensional channel flow this length scale is the aperture of the bottle neck, i.e., the region having the smallest aperture. In two dimensions, the concept of a bottle neck is generalized to that of a minimal path normal to the flow. The length scale is then the average aperture along this path. There is a linear relationship between the first arrival time and this length scale, even when there is strong overlap between the fracture surfaces creating areas with zero permeability. We express the first arrival time directly in terms of the permeability.Comment: EPL (2012)

Parenting Enhancement, Interpersonal Psychotherapy to Reduce Depression in Low-Income Mothers of Infants and Toddlers: A Randomized Trial

Depressive symptoms and clinical depression are highly prevalent in low-income mothers and negatively affect their infants and toddlers

Short-term in-home intervention reduces depressive symptoms in early head start Latina mothers of infants and toddlers

Depressive symptoms may compromise the ability of low-income Latina mothers with limited English language proficiency to parent their infants or toddlers. Eighty Early Head Start Latina mothers with limited English language proficiency were randomized to an advanced practice nurse-delivered, culturally tailored, in-home psychotherapy intervention, or to usual care. Repeated measures regression analysis showed a significantly greater decrease in depressive symptoms for intervention mothers compared to the usual care group at 22 and 26 weeks (4 weeks post intervention). Intervention mothers’ reports of their child's aggression diminished significantly from T1 to T4 compared to usual care mothers (p= .03). Self-efficacy appeared to only partially mediate the intervention effect, and maternal health moderated the intervention impact. Results indicate that the intervention reduced depressive symptoms and, compared to previous studies in this population, retention of mothers in both intervention and control conditions was improved

Interpersonal Psychotherapy With a Parenting Enhancement Adapted for In-Home Delivery in Early Head Start.

Formidable barriers prevent low-income mothers from accessing evidence-based treatment for depressive symptoms that compromise their ability to provide sensitive, responsive parenting for their infant or toddler. Interpersonal psychotherapy (IPT), an evidence-based psychotherapy for depression, was tailored for in-home delivery to mothers navigating economic hardship and other intense Stressors, and for Latina mothers with limited English language proficiency. Psychiatric-mental health nurses delivered the adapted IPT in randomized clinical trials that were conducted in partnership with Early Head Start (EHS). The authors discuss the results of these studies and the impacts on EHS staff members and programs, and they provide additional implications for current early childhood-focused programs

Dynamics of sleep-wake cyclicity in developing rats

Adult mammals cycle between periods of sleep and wakefulness. Recent assessments of these cycles in humans and other mammals [Lo, C. C., Amaral, L. A. N., Havlin, S., Ivanov, P. Ch., Penzel, T., Peter, J. H. & Stanley, H. E. (2002) Europhys. Lett. 57, 625-631 and Lo, C. C., Chou, T., Penzel, T., Scammell, T. E., Strecker, R. E., Stanley, H. E. & Ivanov, P. Ch. (2004) Proc. Natl. Acad. Sci. 101, 17545-17548] indicate that sleep bout durations exhibit an exponential distribution, whereas wake bout durations exhibit a power-law distribution. Moreover, it was found that wake bout distributions, but not sleep bout distributions, exhibit scale invariance across mammals of different body sizes. Here we test the generalizability of these findings by examining the distributions of sleep and wake bout durations in infant rats between 2 and 21 days of age. In agreement with Lo et al., we find that sleep bout durations exhibit exponential distributions at all ages examined. In contrast, however, wake bout durations also exhibit exponential distributions at the younger ages, with a clear power-law distribution only emerging at the older ages. Further analyses failed to find substantial evidence either of short- or long-term correlations in the data, thus suggesting that the durations of current sleep and wake bouts evolve through time without memory of the durations of preceding bouts. These findings further support the notion that bouts of sleep and wakefulness are regulated independently. Moreover, in light of recent evidence that developmental changes in sleep and wake bouts can be attributed in part to increasing forebrain influences, these findings suggest the possibility of identifying specific neural circuits that modulate the changing complexity of sleep and wake dynamics during development