Odor-driven attractor dynamics in the antennal lobe allow for simple and rapid olfactory pattern classification

The antennal lobe plays a central role for odor processing in insects, as demonstrated by electrophysiological and imaging experiments. Here we analyze the detailed temporal evolution of glomerular activity patterns in the antennal lobe of honeybees. We represent these spatiotemporal patterns as trajectories in a multidimensional space, where each dimension accounts for the activity of one glomerulus. Our data show that the trajectories reach odor-specific steady states (attractors) that correspond to stable activity patterns at about 1 second after stimulus onset. As revealed by a detailed mathematical investigation, the trajectories are characterized by different phases: response onset, steady-state plateau, response offset, and periods of spontaneous activity. An analysis based on support-vector machines quantifies the odor specificity of the attractors and the optimal time needed for odor discrimination. The results support the hypothesis of a spatial olfactory code in the antennal lobe and suggest a perceptron-like readout mechanism that is biologically implemented in a downstream network, such as the mushroom body

Summary of 1978 Southeastern Virginia Urban Plume study: Aircraft results for carbon monoxide, methane, nonmethane hydrocarbons, and ozone

The characteristics of the Southeastern Virginia urban plume were defined with emphasis on the photon-oxidant species. The measurement area was a rectangle, approximately 150 km by 100 km centered around Cape Charles, Virginia. Included in this area are the cities of Norfolk, Virginia Beach, Chesapeake, Newport News, and Hampton. The area is bounded on the north by Wallops Island, Virginia, and on the south by the Hampton Roads area of Tidewater Virginia. The major axis of the rectangle is oriented in the southwest-northeast direction. The data set includes aircraft measurements for carbon monoxide, methane, nonmethane hydrocarbons, and ozone. The experiment shows that CO can be successfully measured as a tracer gas and used as an index for determining localized and urban plumes. The 1978 data base provided sufficient data to assess an automated chromatograph with flame ionization detection used for measuring methane and nonmethane hydrocarbons in flight

Puckering Free Energy of Pyranoses: an NMR and Metadynamics--Umbrella Sampling Investigation

We present the results of a combined metadynamics--umbrella sampling investigation of the puckered conformers of pyranoses described using the gromos 45a4 force field. The free energy landscape of Cremer--Pople puckering coordinates has been calculated for the whole series of alpha and beta aldohexoses, showing that the current force field parameters fail in reproducing proper puckering free energy differences between chair conformers. We suggest a modification to the gromos 45a4 parameter set which improves considerably the agreement of simulation results with theoretical and experimental estimates of puckering free energies. We also report on the experimental measurement of altrose conformers populations by means of NMR spectroscopy, which show good agreement with the predictions of current theoretical models

Reconstructive description of eighteenth-century Xinka grammar

This dissertation presents a comprehensive description of Xinka based on the missionary grammar "Arte de la lengua szinca" that was written by the priest Manuel Maldonado de Matos around 1773. Xinka is an isolate family of today mostly extinct, closely related languages in southeastern Guatemala. The "Arte de la lengua szinca" is the earliest source on Xinka grammar that is otherwise not well documented or described. The analysis of the late colonial grammar draws on comparative data, including (a) primary data that were documented by the author with the last Xinka-speakers in Guazacapán, Santa Rosa, Guatemala between 2000-03, and (b) further secondary linguistic data of Xinkan languages from the towns of Guazacapán, Chiquimulilla, Yupiltepeque, Jumaytepeque, Sinacantán and Jutiapa. The text addresses the methodological implications of describing colonial Xinka grammar based on such a heterogeneous corpus of diachronic and regionally diverse data. Besides the linguistic description, the dissertation contains information about the cultural context of the language as well as about the colonial document and the corpus of linguistic data. The appendix includes a concordance of the linguistic data from the colonial grammar and a dictionary of the lexical entries.LEI Universiteit LeidenLanguage Use in Past and Presen

Trying to define Free Will : a cognitive and fonctional model proposal

The debate about Free Will has been in the human mind for centuries, but has become even more intense with the recent scientific findings adding new lights on the problem. This interdisciplinary explosion of interest for the topic has brought many insightful knowledge, but also a great deal of epistemological problems. We think that those epistemological problems are deeply related to the very definition of Free Will and how this definition interacts with the interpretations of experimental results. We will thus outline a few of these problems and then propose a definition of Free Will which takes into account those epistemological pitfalls

Anti-inflammatory effects of ciprofloxacin in S. aureus Newman induced nasal inflammation in vitro

<p>Abstract</p> <p>Objectives</p> <p>Chronic rhinosinusitis (CRS) is a chronic inflammatory disease of the nasal mucosa. Recent studies suggest that <it>S. aureus </it>enterotoxins may play an etiologic role in the development of CRS. Apart from surgery and repeated courses of steroids, macrolide antibiotics have been reported to exert anti-inflammatory effects in CRS. Similar effects have been reported for fluoroquinolones on various cell types. Since these effects have poorly been characterized in CRS, we examined anti-inflammatory effects of ciprofloxacin on human nasal epithelial cells (HNECs).</p> <p>Methods</p> <p>Inflammation was induced in HNECs cultured from nasal turbinate mucosa with supernatants of <it>S. aureus Newman </it>for 12 hours. Subsequently, HNECs were coincubated with <it>S. aureus Newman </it>and ciprofloxacin (1.5 × 10^-5M), clarithromycin (10^-6M) or prednisolone (10^-5M) for another 12 hours. IL-8 synthesis was quantified after 12 and 24 hours by ELISA.</p> <p>Results</p> <p>Stimulation with <it>S. aureus Newman </it>supernatants was associated with an increase of IL-8 synthesis after 12 hours in all experiments. During the second 12 hours, IL-8 synthesis decreased and this effect was independent from any stimulus or inhibitor. However, coincubation of HNECs with ciprofloxacin was associated with a more extensive decrease of IL-8 synthesis. Similarly, addition of clarithromycin was associated with a reduction of IL-8 synthesis although this effect was not significant. Coincubation with prednisolone resulted in a significant reduction of IL-8 levels.</p> <p>Conclusion</p> <p>Ciprofloxacin exerts anti-inflammatory effects in <it>S. aureus Newman </it>driven nasal inflammation. Inhibitory effects were comparable to those of prednisolone and clarithromycin.</p

Interference of Higgs boson resonances in mu^+ mu^- -> neutralino_i neutralino_j with longitudinal beam polarization

We study the interference of resonant Higgs boson exchange in neutralino production in \mu^+ \mu^- annihilation with longitudinally polarized beams. We use the energy distribution of the decay lepton in the process \neutralino_j \to \ell^\pm \slepton^\mp to determine the polarization of the neutralinos. In the CP conserving Minimal Supersymmetric Standard Model a non-vanishing asymmetry in the lepton energy spectrum is caused by the interference of Higgs boson exchange channels with different CP eigenvalues. The contribution of this interference is large if the heavy neutral bosons H and A are nearly degenerate. We show that the asymmetry can be used to determine the couplings of the neutral Higgs bosons to the neutralinos. In particular, the asymmetry allows to determine the relative phase of the couplings. We find large asymmetries and cross sections for a set of reference scenarios with nearly degenerate neutral Higgs bosons.Comment: 20 pages, 6 figures, minor typos corrected, to appear in Eur. Phys. J.

Cardiac cell modelling: Observations from the heart of the cardiac physiome project

In this manuscript we review the state of cardiac cell modelling in the context of international initiatives such as the IUPS Physiome and Virtual Physiological Human Projects, which aim to integrate computational models across scales and physics. In particular we focus on the relationship between experimental data and model parameterisation across a range of model types and cellular physiological systems. Finally, in the context of parameter identification and model reuse within the Cardiac Physiome, we suggest some future priority areas for this field

Long-Term Recurrence of Nonmelanoma Skin Cancer after Topical Methylaminolevulinate Photodynamic Therapy in a Dermato-Oncology Department

BACKGROUND: Most available studies on the efficacy of topical photodynamic therapy focus on short-to medium-term results. Long-term data are scarce. OBJECTIVE: To evaluate the long-term efficacy of photodynamic therapy with topical methylaminolevulinate to treat Bowen's disease and basal cell carcinoma in the clinical practice setting of a dermato-oncology department. METHODS: The study included patients diagnosed with Bowen's disease or basal cell carcinoma, and who received photodynamic therapy from 2004 to 2008. Treatment protocol and clinical follow-up were standardized. The primary endpoint was clinically observed recurrence in a previous photodynamic therapy-treated area. Descriptive and survival analyses were performed. RESULTS: A total of 31 Bowen's disease lesions and 44 superficial basal cell carcinoma were treated, with a median follow-up of 43.5 months. Recurrence was observed in 14 Bowen's disease lesions (53.8%) and in 11 superficial basal cell carcinoma (33.3%). Significantly higher estimates for recurrence rates were found in patients with Bowen's disease (p=0.0036) or those aged under 58 years (p=0.039). The risk of recurrence was higher in patients with Bowen's disease than in those with superficial basal cell carcinoma and younger patients. CONCLUSIONS: Recurrence should be considered when choosing to treat non-melanoma skin cancer with photodynamic therapy. Younger age and Bowen's disease were independent predictors for long-term recurrence, suggesting the need to establish an extended period of follow-up for this subset of patients