High-resolution imaging of single fluorescent molecules with the optical near-field of a metal tip

We show that a concentration of light at a metal tip allows near-field optical imaging of single fluorescent dye molecules at very high resolution, despite strong quenching effects. Details as small as 10 nm were observed in the fluorescence patterns of single Cy-3 dyes bound to the termini of DNA. Data evaluation by model fitting determines the positions of the dyes to an accuracy even better than 1 nm and also yields their 3D orientation. The metal tip simultaneously provides high-resolution topographic imaging complementing the optical signal for a detailed surface examination.     

Regulation of stearoyl-CoA desaturase-1 after central and peripheral nerve lesions

Background  

Interruption of mature axons activates a cascade of events in neuronal cell bodies which leads to various outcomes from functional regeneration in the PNS to the failure of any significant regeneration in the CNS. One factor which seems to play an important role in the molecular programs after axotomy is the stearoyl Coenzyme A-desaturase-1 (SCD-1). This enzyme is needed for the conversion of stearate into oleate. Beside its role in membrane synthesis, oleate could act as a neurotrophic factor, involved in signal transduction pathways via activation of protein kinases C.     

Korn's inequalities for piecewise vector fields

Korn's inequalities for piecewise vector fields are established. They can be applied to classical nonconforming finite element methods, mortar methods and discontinuous Galerkin methods.

     

Mechanisms determining the salience of coloration in echoed sound: influence of interaural time and level differences

This study investigates whether the salience of the pitch associated with a single reflection of a broadband sound, such as noise, is determined by the monaural information mediated by the stimuli at the two ears, or by the relative locations of the primary sound and the reflection. Pitch strength was measured as a function of the reflection delay and the lateral displacement between the primary sound and the reflection. Thereby, lateral displacement was produced by means of interaural time differences (ITDs) in experiment 1 and interaural level differences (ILDs) in experiment 3. The results from both experiments are in accordance with the assumption that the strength of the pitch associated with a reflection is based on a central average of the internal representations of the stimuli at the two ears. This notion was corroborated by experiment 2, which showed that the results from experiment 1 could be mimicked by simply adding the stimuli from the two ears and presenting the merged stimulus identically to both ears.     

Embedding optimisation algorithms with Mosel

Algebraic modelling languages allow models to be implemented in such a way that they can easily be understood and modified. They are therefore a working environment commonly used by practitioners in Operations Research. Having once developed models, they need to be integrated inside the company information system. This step often involves embedding a model into a programming language environment: many existing algebraic modelling languages make possible to run parameterised models and subsequently retrieve their results, but without any facility for interacting with the model during the model generation or solution process.In this paper we show how to use the Mosel environment to implement complex algorithms directly in the modelling language.The Office cleaning problem is solved by a branch-and-cut algorithm, implemented entirely in the modelling language (including the definition of the callback function for the solver). Secondly, a cutting stock problem is solved by column generation, also implemented in the modelling language.AMS classification: 90Cxx, 65K05, 68N15     

Network information and connected correlations

Entropy and information provide natural measures of correlation among elements in a network. We construct here the information theoretic analog of connected correlation functions: irreducible N-point correlation is measured by a decrease in entropy for the joint distribution of N variables relative to the maximum entropy allowed by all the observed N-1 variable distributions. We calculate the "connected information" terms for several examples and show that it also enables the decomposition of the information that is carried by a population of elements about an outside source.     

Differential analysis of phosphorylated proteins in resting and thrombin-stimulated human platelets

Blood platelets are important components of haemostasis. After their activation they cause healing of wounds by forming plugs and initiate repair processes. One important event in regulating this activation is the phosphorylation/dephosphorylation of multiple proteins on various tyrosine, serine and threonine residues. To understand the exact molecular mechanisms in platelet activation it is essential to identify proteins involved in the signalling pathways and to localise and characterise their phosphorylation sites. After treatment with ³²P and separation by 2D-PAGE using different pI ranges, phosphorylated platelet proteins were detected by autoradiography. Phosphotyrosine-containing proteins were assigned by immunoblotting with an anti-phosphotyrosine antibody. Another approach for the identification of phosphorylated proteins was immunoprecipitation of tyrosine-phosphorylated proteins using an anti-phosphotyrosine antibody. Protein spots/bands of interest were excised from the gel, digested with trypsin and analysed by MALDI-TOF-MS and nano-LC-ESI-MS/MS, respectively. Several phosphorylated proteins could be identified and the localisation of some in vivo phosphorylation sites was possible.Abbreviations DTT 1,4-dithiothreitol - HCCA -cyano-4-hydroxycinnamic acid - PMSF phenylmethylsulfonylfluoride - PSD post source decay - TFA trifluoroacetic acid - TOF time-of-flight