Bridging the gap: a model of common neural mechanisms underlying the Fröhlich effect, the flash-lag effect, and the representational momentum effect

In recent years, the study and interpretation of mislocalization phenomena observed with moving objects have caused an intense debate about the processing mechanisms underlying the encoding of position. We use a neurophysiologically plausible recurrent network model to explain visual illusions that occur at the start, midposition, and end of motion trajectories known as the Fröhlich, the flash-lag, and the representational momentum effect, respectively. The model implements the idea that trajectories are internally represented by a traveling activity wave in position space, which is essentially shaped by local feedback loops within pools of neurons. We first use experimentally observed trajectory representations in the primary visual cortex of cat to adjust the spatial ranges of lateral interactions in the model.We then show that the readout of the activity profile at adequate points in time during the build-up, midphase, and decay of the wave qualitatively and quantitatively explain the known dependence of the mislocalization errors on stimulus attributes such as contrast and speed. We conclude that cooperative mechanisms within the network may be responsible for the three illusions, with a possible intervention of top-down influences that modulate the efficacy of the lateral interactions.Deutscher Akademischer Austauschdienst (DAAD) / Conselho de Reitores das Universidades Portuguesas (CRUP) - As Acções Integradas Luso - AlemãsBundesministerium für Bildung und Forschungthe (BMBF

Delayed feedback control of periodic orbits in autonomous systems

For controlling periodic orbits with delayed feedback methods the periodicity has to be known a priori. We propose a simple scheme, how to detect the period of orbits from properties of the control signal, at least if a periodic but nonvanishing signal is observed. We analytically derive a simple expression relating the delay, the control amplitude, and the unknown period. Thus, the latter can be computed from experimentally accessible quantities. Our findings are confirmed by numerical simulations and electronic circuit experimentsComment: 4 pages, Revtex, manuscript also available at ftp://athene.fkp.physik.th-darmstadt.de/pub/publications/wolfram/prl_98a/ or at http://athene.fkp.physik.th-darmstadt.de/public/wolfram_publ.htm

Determination of the relative amounts of Gag and Pol proteins in foamy virus particles

We determined the relative ratios of Gag and Pol molecules in highly purified virions of spumaretroviruses or foamy viruses (FVs) using monoclonal antibodies and bacterially expressed reference proteins. We found that the cleaved p68(Gag )moiety dominates in infectious FVs. Furthermore, approximate mean ratios in FV are 16:1 (pr71(Gag )plus p68(Gag):p85(RT)),12:1 (p68(Gag):p85(RT)), and 10:1 (pr71(Gag )plus p68(Gag):p40(IN)). Thus, the results indicate that FVs have found a way to incorporate approximately as much Pol protein into their capsids as orthoretroviruses, despite a completely different Pol expression strategy

ProMEX: a mass spectral reference database for proteins and protein phosphorylation sites

<p>Abstract</p> <p>Background</p> <p>In the last decade, techniques were established for the large scale genome-wide analysis of proteins, RNA, and metabolites, and database solutions have been developed to manage the generated data sets. The Golm Metabolome Database for metabolite data (GMD) represents one such effort to make these data broadly available and to interconnect the different molecular levels of a biological system <abbrgrp><abbr bid="B1">1</abbr></abbrgrp>. As data interpretation in the light of already existing data becomes increasingly important, these initiatives are an essential part of current and future systems biology.</p> <p>Results</p> <p>A mass spectral library consisting of experimentally derived tryptic peptide product ion spectra was generated based on liquid chromatography coupled to ion trap mass spectrometry (LC-IT-MS). Protein samples derived from <it>Arabidopsis thaliana</it>, <it>Chlamydomonas reinhardii</it>, <it>Medicago truncatula</it>, and <it>Sinorhizobium meliloti </it>were analysed. With currently 4,557 manually validated spectra associated with 4,226 unique peptides from 1,367 proteins, the database serves as a continuously growing reference data set and can be used for protein identification and quantification in uncharacterized biological samples. For peptide identification, several algorithms were implemented based on a recently published study for peptide mass fingerprinting <abbrgrp><abbr bid="B2">2</abbr></abbrgrp> and tested for false positive and negative rates. An algorithm which considers intensity distribution for match correlation scores was found to yield best results. For proof of concept, an LC-IT-MS analysis of a tryptic leaf protein digest was converted to mzData format and searched against the mass spectral library. The utility of the mass spectral library was also tested for the identification of phosphorylated tryptic peptides. We included <it>in vivo </it>phosphorylation sites of <it>Arabidopsis thaliana </it>proteins and the identification performance was found to be improved compared to genome-based search algorithms. Protein identification by ProMEX is linked to other levels of biological organization such as metabolite, pathway, and transcript data. The database is further connected to annotation and classification services via BioMoby.</p> <p>Conclusion</p> <p>The ProMEX protein/peptide database represents a mass spectral reference library with the capability of matching unknown samples for protein identification. The database allows text searches based on metadata such as experimental information of the samples, mass spectrometric instrument parameters or unique protein identifier like AGI codes. ProMEX integrates proteomics data with other levels of molecular organization including metabolite, pathway, and transcript information and may thus become a useful resource for plant systems biology studies. The ProMEX mass spectral library is available at <url>http://promex.mpimp-golm.mpg.de/</url>.</p

Extrinsic allergic alveolitis caused by misting fountains

SummaryRecently, an increasing number of patients were presented to our clinics with febrile and respiratory symptoms associated with exposure to a new type of domestic ultrasonic humidifier.We report on 11 patients who developed recurrent episodes of fever, cough and dyspnea after repeated exposure to ultrasonic misting fountains at home. A diagnosis of extrinsic allergic alveolitis (EAA) or toxic alveolitis was made on the basis of the history and the clinical, radiological, laboratory and immunological findings. Eight patients were subjected to inhalative challenge tests with their own ultrasonic misting fountains, and all of them exhibited positive reactions.Nine patients were diagnosed with an EAA (humidifier lung) and two patients with a toxic alveolitis (humidifier fever).This study demonstrates the potential for ultrasonic misting fountains to cause illness in the home. In view of the increasing popularity of these devices, humidifier lung and humidifier fever should be considered in the differential diagnosis of patients with unexplained pulmonary or flu-like illnesses with fever

Energy Elasticity on Heterogeneous Hardware using Adaptive Resource Reconfiguration LIVE

Energy awareness of database systems has emerged as a critical research topic, since energy consumption is becoming a major limiter for their scalability. Recent energy-related hardware developments trend towards offering more and more configuration opportunities for the software to control its own energy consumption. Existing research so far mainly focused on leveraging this configuration spectrum to find the most energy-efficient configuration for specific operators or entire queries. In this demo, we introduce the concept of energy elasticity and propose the energy-control loop as an implementation of this concept. Energy elasticity refers to the ability of software to behave energy-proportional and energy-efficient at the same time while maintaining a certain quality of service. Thus, our system does not draw the least energy possible but the least energy necessary to still perform reasonably. We demonstrate our overall approach using a rich interactive GUI to give attendees the opportunity to learn more about our concept

Using the Inelastic Background in Hard X-Ray Photoelectron Spectroscopy for a Depth-Resolved Analysis of the Cds / CU(In,GA)SE \u3c Inf \u3e 2 \u3c / Inf \u3e Interface

The inelastic background of hard x-ray photoelectron spectroscopy data is analyzed to paint a depth-resolved picture of the CdS/Cu(In,Ga)Se2 (CdS/CIGSe) layer structure. The CdS/CIGSe interface is the central component in next-generation chalcopyrite thin-film photovoltaic devices. By analyzing both, the (unscattered) core-level peaks and the inelastic background, and by varying the excitation photon energy from 2.1 up to 14 keV, we can derive photoemission information over a broad range of electron kinetic energies and, hence, sampling depths. With this complementary information, the CdS film thickness of a CdS/CIGSe interface can be accurately determined as a function of the CdS deposition time. For the thinner CdS films, the film thickness can be shown to vary laterally. Furthermore, small amounts of Se and process-related Rb can be detected in a thin (∼2 nm) surface layer of all investigated CdS films