Negative responses of highland pines to anthropogenic activities in inland Spain: a palaeoecological perspective

Palaeoecological evidence indicates that highland pines were dominant in extensive areas of the mountains of Central and Northern Iberia during the first half of the Holocene. However, following several millennia of anthropogenic pressure, their natural ranges are now severely reduced. Although pines have been frequently viewed as first-stage successional species responding positively to human disturbance, some recent palaeobotanical work has proposed fire disturbance and human deforestation as the main drivers of this vegetation turnover. To assess the strength of the evidence for this hypothesis and to identify other possible explanations for this scenario, we review the available information on past vegetation change in the mountains of northern inland Iberia. We have chosen data from several sites that offer good chronological control, including palynological records with microscopic charcoal data and sites with plant macro- and megafossil occurrence. We conclude that although the available long-term data are still fragmentary and that new methods are needed for a better understanding of the ecological history of Iberia, fire events and human activities (probably modulated by climate) have triggered the pine demise at different locations and different temporal scales. In addition, all palaeoxylological, palynological and charcoal results obtained so far are fully compatible with a rapid human-induced ecological change that could have caused a range contraction of highland pines in western Iberia

Reconstructing charge-carrier dynamics in porous silicon membranes from time-resolved interferometric measurements

We performed interferometric time-resolved simultaneous reflectance and transmittance measurements to investigate the carrier dynamics in pump-probe experiments on thin porous silicon membranes. The experimental data was analysed by using a method built on the Wentzel-Kramers-Brillouin approximation and the Drude model, allowing us to reconstruct the excited carriers’ non-uniform distribution in space and its evolution in time. The analysis revealed that the carrier dynamics in porous silicon, with ~50% porosity and native oxide chemistry, is governed by the Shockley-Read-Hall recombination process with a characteristic time constant of 375 picoseconds, whereas diffusion makes an insignificant contribution as it is suppressed by the high rate of scattering

Developmental malformation of the corpus callosum: a review of typical callosal development and examples of developmental disorders with callosal involvement

This review provides an overview of the involvement of the corpus callosum (CC) in a variety of developmental disorders that are currently defined exclusively by genetics, developmental insult, and/or behavior. I begin with a general review of CC development, connectivity, and function, followed by discussion of the research methods typically utilized to study the callosum. The bulk of the review concentrates on specific developmental disorders, beginning with agenesis of the corpus callosum (AgCC)—the only condition diagnosed exclusively by callosal anatomy. This is followed by a review of several genetic disorders that commonly result in social impairments and/or psychopathology similar to AgCC (neurofibromatosis-1, Turner syndrome, 22q11.2 deletion syndrome, Williams yndrome, and fragile X) and two forms of prenatal injury (premature birth, fetal alcohol syndrome) known to impact callosal development. Finally, I examine callosal involvement in several common developmental disorders defined exclusively by behavioral patterns (developmental language delay, dyslexia, attention-deficit hyperactive disorder, autism spectrum disorders, and Tourette syndrome)

Neurovascular unit dysfunction with blood-brain barrier hyperpermeability contributes to major depressive disorder: a review of clinical and experimental evidence

About one-third of people with major depressive disorder (MDD) fail at least two antidepressant drug trials at 1 year. Together with clinical and experimental evidence indicating that the pathophysiology of MDD is multifactorial, this observation underscores the importance of elucidating mechanisms beyond monoaminergic dysregulation that can contribute to the genesis and persistence of MDD. Oxidative stress and neuroinflammation are mechanistically linked to the presence of neurovascular dysfunction with blood-brain barrier (BBB) hyperpermeability in selected neurological disorders, such as stroke, epilepsy, multiple sclerosis, traumatic brain injury, and Alzheimer’s disease. In contrast to other major psychiatric disorders, MDD is frequently comorbid with such neurological disorders and constitutes an independent risk factor for morbidity and mortality in disorders characterized by vascular endothelial dysfunction (cardiovascular disease and diabetes mellitus). Oxidative stress and neuroinflammation are implicated in the neurobiology of MDD. More recent evidence links neurovascular dysfunction with BBB hyperpermeability to MDD without neurological comorbidity. We review this emerging literature and present a theoretical integration between these abnormalities to those involving oxidative stress and neuroinflammation in MDD. We discuss our hypothesis that alterations in endothelial nitric oxide levels and endothelial nitric oxide synthase uncoupling are central mechanistic links in this regard. Understanding the contribution of neurovascular dysfunction with BBB hyperpermeability to the pathophysiology of MDD may help to identify novel therapeutic and preventative approaches

Elastic guided waves in a layered plate with rectangular cross section

Guided waves in a layered elastic plate of rectangular cross section (finite width and thickness) has been studied in this paper. A semianalytical finite element method in which the deformation of the cross section is modeled by two-dimensional finite elements and analytical representation of propagating waves along the length of the plate has been used. The method is applicable to arbitrary number of layers and general anisotropic material properties of each layer, and is similar to the stiffness method used earlier to study guided waves in a laminated composite plate of infinite width. Numerical results showing the effect of varying the width of the plate on the dispersion of guided waves are presented and are compared with those for an infinite plate. In addition, effect of thin anisotropic coating or interface layers on the guided waves is investigated. (C) 2002

Prediction of final height in short, normal and tall children

Measurements of final height were made on more than 4000 children in the final grade of school in Gothenburg in 1992, at the same time, mid-parental heights were recorded. These data were combined with other information (sex, length of gestation, size at birth, estimated age at peak height velocity (PHV) and height measurements made before 8 years of age) and used in a multiple regression analysis to assess the strength of the linear relationship between attained final height and these other potentially predictive measures of adult height. The R2 value increased from 0.16 at birth to 0.64 when the child was 8 years old. The inclusion of mid-parental height in the regression analysis contributed significantly to the explained variation in final height, especially at the earlier ages; the further addition of size at birth and age at PHV provides a small increase in the explained variation. The probability that the final height of a child will be below -2 or above +2 standard deviation scores (SDS) was assessed, based on previous SDS values for height when younger and on mid-parental height SDS. As a result of the large sample size included in the analyses, considerable confidence can be placed on the accurate prediction of final height values in the range -2.5 to +2.5 SDS.link_to_subscribed_fulltex