Evidence of early development of action planning in the human foetus: a kinematic study

The aim of the present study was to investigate whether foetal hand movements are planned and how they are executed. We performed a kinematic analysis of hand movements directed towards the mouth and the eyes in the foetuses of eight women with normally evolving pregnancies. At 14, 18 and 22 weeks of gestation, eight foetuses underwent a 20-min four-dimensional-ultrasound session. The video recordings for these movements were then imported into in-house software developed to perform kinematic analysis. We found that spatial and temporal characteristics of foetal movements are by no means uncoordinated or unpatterned. By 22 weeks of gestation the movements seem to show the recognizable form of intentional actions, with kinematic patterns that depend on the goal of the action, suggesting a surprisingly advanced level of motor planning.     

Temporal response of medical liquid crystal displays

Displays based on liquid crystal technology suffer from slow temporal response due to the dynamics of the molecular rearrangement in response to a pixel voltage change. A slow display can affect the visualization by the human observer of subtle contrast in dynamic presentation of volumetric image datasets or real-time image sequences. In this paper, we describe a measurement method for the characterization of the temporal response of medical liquid crystal displays (LCDs). The ratio of luminance difference to noise at the gray levels of concern determines the reliability of measurements. Coefficients of variations are used to represent the measurement reliability. We optimized the repeatability of most response time measurements to less than 10%. However, poor repeatability is encountered for the response of adjacent gray levels. 256 X 255 inter-gray-level transition time matrices were measured for four medical displays and one high-definition TV LCD display. Response times range from below 20 ms to above 150 ms. For each display, response times are not uniformly distributed, with a faster response for large gray-level transitions. Transition times are smaller when the starting gray level is between 10 and 20 for a target between 25 and 150. The difference could be over 100 ms for different transitions within a display. For transitions with poor temporal response, the luminance after 1, 3, and 5 frames reaches only 12, 45, and 75% of the target value, respectively. We also found that LCD response time depends on temperature, with 1 h warm-up reducing the response time by a factor of 2.     

Electrocardiogram in Friedreich's ataxia: A short-term surrogate endpoint for treatment efficacy

Friedreich's ataxia is a rare degenerative neuromuscular disorder, caused by a homozygous GAA triplet repeat expansion in the frataxin (FXN) gene, with a broad clinical phenotype characterized by progressive gait and limb ataxia, dysarthria, and loss of lower limb reflexes; cardiac involvement is represented by hypertrophic cardiomyopathy, ventricular arrhythmias, and sudden cardiac deaths. Currently, no definite therapy is available, while many drugs are under investigation; for this reasons, we need markers of short- and long-term treatment efficacy acting on different tissue for trial evaluation. We describe the case of a 21-year-old patient affected by Friedreich's ataxia on wheel-chair, with initial cardiac involvement and electrocardiographic features characterized by thiamine treatment-related negative T wave and QTc variations. We discuss plausible physiopathology and potential ECG role implications as an intermediate marker of treatment response in future clinical trials considering patients affected by Friedreich's ataxia.     

Functional traits explain variation in plant life history strategies

Ecologists seek general explanations for the dramatic variation in species abundances in space and time. An increasingly popular solution is to predict species distributions, dynamics, and responses to environmental change based on easily measured anatomical and morphological traits. Trait-based approaches assume that simple functional traits influence fitness and life history evolution, but rigorous tests of this assumption are lacking, because they require quantitative information about the full lifecycles of many species representing different life histories. Here, we link a global traits database with empirical matrix population models for 222 species and report strong relationships between functional traits and plant life histories. Species with large seeds, long-lived leaves, or dense wood have slow life histories, with mean fitness (i.e., population growth rates) more strongly influenced by survival than by growth or fecundity, compared with fast life history species with small seeds, short-lived leaves, or soft wood. In contrast to measures of demographic contributions to fitness based on whole lifecycles, analyses focused on raw demographic rates may underestimate the strength of association between traits and mean fitness. Our results help establish the physiological basis for plant life history evolution and show the potential for trait-based approaches in population dynamics.Recent evidence for global patterns of functional variation in plants, such as the leaf economics spectrum (1, 2), the wood economics spectrum (3), and the seed size–seed number tradeoff (4, 5), has convinced many ecologists that functional traits offer the best available approach for achieving a general predictive understanding of communities and ecosystems (6, 7). Trait-based approaches are now being used to predict the outcome of community assembly (8–10), global vegetation dynamics (11), and the rate of ecosystem processes (6, 12–14). A central assumption of trait-based ecology is that morphological traits determine physiological performance, which influences vital rates and determines individual fitness and life history evolution (15, 16). However, because of the challenge of quantifying the contribution of traits to fitness, the assumed links between functional traits and life history have not been fully tested.Research in tropical and Mediterranean forests has revealed cross-species relationships between functional traits and the survival and growth rates of individuals (3, 17–24). Although these relationships provide evidence that functional traits influence vital rates, they offer only limited insight into associations between those traits and individual fitness and life history. Vital rates (e.g., survival and fecundity) represent fitness components, but their influence on mean fitness, defined as the population growth rate (λ), is best understood in the context of the full lifecycle of a species (25, 26). A significant negative correlation between wood density and individual growth (18) might not translate into a significant effect on mean fitness if individual growth has little influence on λ. Conversely, a weak relationship between a functional trait and another vital rate could have a significant effect on mean fitness if that vital rate has a strong influence on λ. Perturbation analyses, such as the sensitivities and elasticities frequently applied to matrix projection models (27), address this problem by quantifying the contribution of vital rates to λ (28), making it possible to characterize a species'' overall life history in terms of the relative importance of survival, individual growth, and fecundity to mean fitness. Species with slow life histories have population growth rates with high elasticities to survival, whereas species with fast life histories have relatively higher elasticities to individual growth or fecundity (29, 30).Armed with vital rate elasticities, we can test quantitative hypotheses about whether functional tradeoffs scale up to generate life history tradeoffs. For example, plants can allocate their reproductive effort to provision a few large seeds, which tolerate low light and resource availability and have a high survival probability, or they can spread their reproductive effort among many small seeds, maximizing fitness under high resource availability (31, 32). If this functional tradeoff at the seedling stage translates into a life history tradeoff, seed mass should be positively related to the elasticity of the population growth rate to survival and negatively related to elasticities to individual growth and fecundity. The leaf economics spectrum represents another allocation tradeoff. Species can construct long-lived, well-defended leaves that are often favored in low resource environments or build leaves that assimilate carbon quickly under conditions of high resource availability but are prone to rapid tissue loss (1, 33). Species with slow leaf economics traits, such as long leaf lifespans, low specific leaf area (SLA), and low leaf N, might also lead slow lives, characterized by high elasticities to survival and low elasticities to individual growth and recruitment. A wood economics spectrum also exists: species with dense wood tend to have higher survival but lower relative growth rates than species with soft wood (3, 34). Elasticities to survival should increase with wood density, whereas elasticities to individual growth and fecundity should decrease.The main obstacle in testing these hypotheses is availability of the detailed demographic data necessary to describe a species’ full lifecycle and estimate vital rate elasticities. We overcame this limitation by crossing the TRY Global Plant Traits Database (35) with the COMPADRE Plant Matrix Database (www.compadre-db.org/), a collection of published matrix population models. This approach produced a dataset of 222 plant species spanning a global range of biomes and perennial growth forms (Table S1), for which we have at least one functional trait measurement as well as a matrix population model that we used to calculate the elasticity of the population growth rate to each of the three vital rates: survival, growth, and fecundity (30).Our primary objective was to evaluate the ability of functional traits to explain variation across species in life history, which we quantified with vital rate elasticities. Our secondary objective was to evaluate whether inferences about life history can be drawn directly from the raw vital rates, which would save researchers the considerable time and effort required to parameterize population models and calculate elasticities. We used two statistical approaches to quantify relationships between vital rate elasticities and seed mass, wood density, and leaf economics traits (leaf lifespan, SLA, and leaf N). Dirichlet regression is a multivariate approach that accounts for the fact that the survival, growth, and fecundity elasticities for each species sum to one but does not account for phylogenetic relationships. Phylogenetic generalized least squares (PGLS) regression ignores the nonindependence of the elasticities but accounts for phylogenetic relationships. We repeated both types of regressions with plant growth form and then biome included as covariates to confirm that trait effects did not simply represent differences between trees and herbaceous species or plants adapted to different environments.