Dynamics of cluster deposition on Ar surface

Using a combined quantum mechanical/classical method, we study the dynamics of deposition of small Na clusters on Ar(001) surface. We work out basic mechanisms by systematic variation of substrate activity, impact energy, cluster orientations, cluster sizes, and charges. The soft Ar material is found to serve as an extremely efficient shock absorber which provides cluster capture in a broad range of impact energies. Reflection is only observed in combination with destruction of the substrate. The kinetic energy of the impinging cluster is rapidly transfered at first impact. The distribution of the collision energy over the substrate proceeds very fast with velocity of sound. The full thermalization of ionic and atomic energies goes at a much slower pace with times of several ps. Charged clusters are found to have a much stronger interface interaction and thus get in significantly closer contact with the surface.Comment: 10 pages, 6 figures, accepted in Euro. Phys. J.

Dynamics of metal clusters in rare gas clusters

We investigate the dynamics of Na clusters embedded in Ar matrices. We use a hierarchical approach, accounting microscopically for the cluster's degrees of freedom and more coarsely for the matrix. The dynamical polarizability of the Ar atoms and the strong Pauli-repulsion exerted by the Ar-electrons are taken into account. We discuss the impact of the matrix on the cluster gross properties and on its optical response. We then consider a realistic case of irradiation by a moderately intense laser and discuss the impact of the matrix on the hindrance of the explosion, as well as a possible pump probe scenario for analyzing dynamical responses.Comment: Proceedings of the 30th International Workshop on Condensed Matter Theories, Dresden, June 05 - 10, 2006, World Scientific. 3 figure

Hindered Coulomb explosion of embedded Na clusters -- stopping, shape dynamics and energy transport

We investigate the dynamical evolution of a Na$_8$ cluster embedded in Ar matrices of various sizes from N=30 to 1048. The system is excited by an intense short laser pulse leading to high ionization stages. We analyze the subsequent highly non-linear motion of cluster and Ar environment in terms of trajectories, shapes, and energy flow. The most prominent effects are: temporary stabilization of high charge states for several ps, sudden stopping of the Coulomb explosion of the embedded Na$_8$ clusters associated with an extremely fast energy transfer to the Ar matrix, fast distribution of energy throughout the Ar layers by a sound wave. Other ionic-atomic transfer and relaxation processes proceed at slower scale of few ps. The electron cloud is almost thermally decoupled from ions and thermalizes far beyond the ps scale.Comment: 12 pages, 10 figures, accepted in Euro. Phys. J.

Plasma 1-deoxysphingolipids are early predictors of incident type 2 diabetes mellitus.

1-Deoxysphingolipids (1-deoxySLs) are atypical sphingolipids, which are formed in a side reaction during sphingolipid de-novo synthesis. Recently, we demonstrated that 1-deoxySLs are biomarkers for the prediction of T2DM in obese, non-diabetic patients. Here we investigated the relevance of 1-deoxySLs as long-term predictive biomarkers for the incidence of T2DM in an asymptomatic population. Here, we analyzed the plasma sphingoid base profile in a nested group of non-diabetic individuals (N = 605) selected from a population-based study including 5 year follow-up data (CoLaus study). 1-DeoxySLs at baseline were significantly elevated in individuals who developed T2DM during the follow-up (p<0.001), together with increased glucose (p<5.11E-14), triglycerides (p<0.001) and HOMA-IR indices (p<0.001). 1-Deoxy-sphinganine (1-deoxySA) and 1-deoxy-sphingosine (1-deoxySO) were predictive for T2DM, even after adjusting for fasting glucose levels in the binary regression analyses. The predictive value of the combined markers 1-deoxySA+glucose were superior to glucose alone in normal-weight subjects (p<0.001) but decreased substantially with increasing BMI. Instead, plasma adiponectin and waist-to-hip ratio appeared to be better risk predictors for obese individuals (BMI>30kg/m2). In conclusion, elevated plasma 1-deoxySL levels are strong and independent risk predictors of future T2DM, especially for non-obese individuals in the general population

Correction: Plasma 1-deoxysphingolipids are early predictors of incident type 2 diabetes mellitus.

[This corrects the article DOI: 10.1371/journal.pone.0175776.]

Visual masking: past accomplishments, present status, future developments

Visual masking, throughout its history, has been used as an investigative tool in exploring the temporal dynamics of visual perception, beginning with retinal processes and ending in cortical processes concerned with the conscious registration of stimuli. However, visual masking also has been a phenomenon deemed worthy of study in its own right. Most of the recent uses of visual masking have focused on the study of central processes, particularly those involved in feature, object and scene representations, in attentional control mechanisms, and in phenomenal awareness. In recent years our understanding of the phenomenon and cortical mechanisms of visual masking also has benefited from several brain imaging techniques and from a number of sophisticated and neurophysiologically plausible neural network models. Key issues and problems are discussed with the aim of guiding future empirical and theoretical research

Evidence of Introgression of the ace-1R Mutation and of the ace-1 Duplication in West African Anopheles gambiae s. s

Background: The role of inter-specific hybridisation is of particular importance in mosquito disease vectors for predicting the evolution of insecticide resistance. Two molecular forms of Anopheles gambiae s.s., currently recognized as S and M taxa, are considered to be incipient sibling species. Hybrid scarcity in the field was suggested that differentiation of M and S taxa is maintained by limited or absent gene flow. However, recent studies have revealed shared polymorphisms within the M and S forms, and a better understanding of the occurrence of gene flow is needed. One such shared polymorphism is the G119S mutation in the ace-1 gene (which is responsible for insecticide resistance); this mutation has been described in both the M and S forms of A. gambiae s.s. Methods and Results: To establish whether the G119S mutation has arisen independently in each form or by genetic introgression, we analysed coding and non-coding sequences of ace-1 alleles in M and S mosquitoes from representative field populations. Our data revealed many polymorphic sites shared by S and M forms, but no diversity was associated with the G119S mutation. These results indicate that the G119S mutation was a unique event and that genetic introgression explains the observed distribution of the G119S mutation within the two forms. However, it was impossible to determine from our data whether the mutation occurred first in the S form or in the M form. Unexpectedly, sequence analysis of some resistant individuals revealed a duplication of the ace-1 gene that was observed in both A. gambiae s.s. M and S forms. Again, the distribution of this duplication in the two forms most likely occurred through introgression. Conclusions: These results highlight the need for more research to understand the forces driving the evolution of insecticide resistance in malaria vectors and to regularly monitor resistance in mosquito populations of Africa