Early dispersal of modern humans in Europe and implications for Neanderthal behaviour

The appearance of anatomically modern humans in Europe and the nature of the transition from the Middle to Upper Palaeolithic are matters of intense debate. Most researchers accept that before the arrival of anatomically modern humans, Neanderthals had adopted several 'transitional' technocomplexes. Two of these, the Uluzzian of southern Europe and the Chatelperronian of western Europe, are key to current interpretations regarding the timing of arrival of anatomically modern humans in the region and their potential interaction with Neanderthal populations. They are also central to current debates regarding the cognitive abilities of Neanderthals and the reasons behind their extinction. However, the actual fossil evidence associated with these assemblages is scant and fragmentary, and recent work has questioned the attribution of the Chatelperronian to Neanderthals on the basis of taphonomic mixing and lithic analysis. Here we reanalyse the deciduous molars from the Grotta del Cavallo (southern Italy), associated with the Uluzzian and originally classified as Neanderthal. Using two independent morphometric methods based on microtomographic data, we show that the Cavallo specimens can be attributed to anatomically modern humans. The secure context of the teeth provides crucial evidence that the makers of the Uluzzian technocomplex were therefore not Neanderthals. In addition, new chronometric data for the Uluzzian layers of Grotta del Cavallo obtained from associated shell beads and included within a Bayesian age model show that the teeth must date to ~45,000-43,000 calendar years before present. The Cavallo human remains are therefore the oldest known European anatomically modern humans, confirming a rapid dispersal of modern humans across the continent before the Aurignacian and the disappearance of Neanderthals.     

Peirce on the justification of abduction

What sort of justification can be claimed for abduction? In this paper we reconstruct Peirce’s answer to this question. We show that in his early works on the logic of science Peirce provided an abductive justification of abduction, and that in his mature writings the early solution is enriched by a reference to the place abduction has in a typical scientific inquiry. Since abduction is the first stage of inquiry by which a hypothesis is suggested and which then has to be subjected to inductive testing, the fundamental abduction (ur-abduction) that justifies abduction has also to be subjected to a verification by means of a fundamental induction (ur-induction), namely that the abduction that abduction is valid is verified by an appeal to the history of science.     

Polyunsaturated fatty acids and cardiovascular disease

Replacing saturated with polyunsaturated (PUFAs) rather than monounsaturated fatty acids or carbohydrates results in cardiovascular prevention over a wide range of intakes. The mechanisms by which PUFAs reduce cardiovascular risk are manifold, and the extent and precise nature of their activities is the subject of several investigations, spanning from in vitro mechanistic studies to human intervention trials. This article reviews the most up-to-date evidence of the association between PUFA consumption and reduced cardiovascular mortality.     

Unidirectional rotation in a mechanically interlocked molecular rotor

Molecular motor proteins are ubiquitous in nature and have inspired attempts to create artificial machines that mimic their ability to produce controlled motion on the molecular level. A recent example of an artificial molecular rotor is a molecule undergoing a unidirectional 120 degrees intramolecular rotation around a single bond; another is a molecule capable of repetitive unimolecular rotation driven by multiple and successive isomerization of its central double bond. Here we show that sequential and unidirectional rotation can also be induced in mechanically interlocked assemblies comprised of one or two small rings moving around one larger ring. The small rings in these [2]- and [3]catenanes move in discrete steps between different binding sites located on the larger ring, with the movement driven by light, heat or chemical stimuli that change the relative affinity of the small rings for the different binding sites. We find that the small ring in the [2]catenane moves with high positional integrity but without control over its direction of motion, while the two rings in the [3]catenane mutually block each other's movement to ensure an overall stimuli-induced unidirectional motion around the larger ring.     

Parameters for reliable results in genetic association studies in common disease.

It is increasingly apparent that the identification of true genetic associations in common multifactorial disease will require studies comprising thousands rather than the hundreds of individuals employed to date. Using 2,873 families, we were unable to confirm a recently published association of the interleukin 12B gene in 422 type I diabetic families. These results emphasize the need for large datasets, small P values and independent replication if results are to be reliable.     

Low-voltage organic transistors with an amorphous molecular gate dielectric

Organic thin film transistors (TFTs) are of interest for a variety of large-area electronic applications, such as displays, sensors and electronic barcodes. One of the key problems with existing organic TFTs is their large operating voltage, which often exceeds 20 V. This is due to poor capacitive coupling through relatively thick gate dielectric layers: these dielectrics are usually either inorganic oxides or nitrides, or insulating polymers, and are often thicker than 100 nm to minimize gate leakage currents. Here we demonstrate a manufacturing process for TFTs with a 2.5-nm-thick molecular self-assembled monolayer (SAM) gate dielectric and a high-mobility organic semiconductor (pentacene). These TFTs operate with supply voltages of less than 2 V, yet have gate currents that are lower than those of advanced silicon field-effect transistors with SiO2 dielectrics. These results should therefore increase the prospects of using organic TFTs in low-power applications (such as portable devices). Moreover, molecular SAMs may even be of interest for advanced silicon transistors where the continued reduction in dielectric thickness leads to ever greater gate leakage and power dissipation.     

Average conditional correlation and tree structures for multivariate GARCH models

We propose a simple class of multivariate GARCH models, allowing for time‐varying conditional correlations. Estimates for time‐varying conditional correlations are constructed by means of a convex combination of averaged correlations (across all series) and dynamic realized (historical) correlations. Our model is very parsimonious. Estimation is computationally feasible in very large dimensions without resorting to any variance reduction technique. We back‐test the models on a six‐dimensional exchange‐rate time series using different goodness‐of‐fit criteria and statistical tests. We collect empirical evidence of their strong predictive power, also in comparison to alternative benchmark procedures. Copyright © 2006 John Wiley & Sons, Ltd.