Characterization of solar-cycle induced frequency shift of medium- and high-degree acoustic modes

Although it is well known that the solar acoustic mode frequency increases as the solar activity increases, the mechanism behind it is still unknown. Mode frequencies with 20 < l < 900 obtained by applying spherical harmonic decomposition to MDI full-disk observations were used. First, the dependence of solar acoustic mode frequency with solar activity was examined and evidence of a quadratic relation was found indicating a saturation effect at high solar activity. Then, the frequency dependence of frequency differences between the activity minimum and maximum was analyzed. The frequency shift scaled by the normalized mode inertia follows a simple power law where the exponent for the p modes decreases by 37% for modes with frequency larger than 2.5 mHz.Comment: Proceedings of GONG-SoHO 24: A new era of seismology of the sun and solar-like star

Evidence of a Quasi-periodic Global-scale Oscillation in the Near-Surface Shear Layer of the Sun

We present evidence of hitherto undiscovered global-scale oscillations in the near-surface shear layer of the Sun. These oscillations are seen as large scale variations of radial shear in both the zonal and meridional flows relative to their mean values. The variations cover all or most of a visible hemisphere, and reverse with a timescale on the order of a solar rotation. A large annual variation in the meridional shear anomaly is understandable in terms of the tilt of the rotation axis, but the rapid oscillations of the shear anomalies in both zonal and the meridional directions appear to be modulated in a more complex, not-quite annual way, although the latter are also strongly modulated by the projected rotational axis angle. Small-scale anomalies in the neighborhood of active regions lend support to their solar origin and physical interpretation. These results were obtained by analyzing ring-diagram fits of low-order modes in high-resolution Doppler data from the Helioseismic and Magnetic Imager on the Solar Dynamics Observatory.Comment: Accepted for publication in Astrophysical Journal Letter

Study of Immobilization by Esteric Bond of 2-(m-Nitrophenyl)-4-(ОІ- Carboxymethyl)-О”2-Oxazolinone-5 on Gellan

The paper studies the coupling reaction, through ester-type covalent bonds, of an oxazolone derived from the N-(m-nitrobenzoyl)-L-asparagic acid, on gellan (a polysaccharide of microbian synthesis), in conditions of activation with dicyclohexyl carbodiimide. Based on a centered, rotatory, composed, second order experimental program, the regression equation describing the dependence of the amount of active principle, chemically bounded to the support, on the reaction’s  parameters (support/active principle ratio, active principle/activator ratio, duration) is obtained. One may observe that the efficiency of the coupling reaction is maximum when employing the parameters’ highest values, over the variation domain established. The coupling product has been characterized through elemental analysis and IR spectroscopy. For the establishment  of the capacity of the active principle’s controlled release by the polymer-active principle system thus obtained, drug’s release kinetics from the polysaccharidic support is studied in conditions of basic hydrolysis. The oxazolone release from the coupling products, by basic hydrolysis proceeds conformely to a zero order kinetics, proving their retard activity

Heterodimerization of Munc13 C2A domain with RIM regulates synaptic vesicle docking and priming

The presynaptic active zone protein Munc13 is essential for neurotransmitter release, playing key roles in vesicle docking and priming. Mechanistically, it is thought that the C2A domain of Munc13 inhibits the priming function by homodimerization, and that RIM disrupts the autoinhibitory homodimerization forming monomeric priming-competent Munc13. However, it is unclear whether the C2A domain mediates other Munc13 functions in addition to this inactivation–activation switch. Here, we utilize mutations that modulate the homodimerization and heterodimerization states to define additional roles of the Munc13 C2A domain. Using electron microscopy and electrophysiology in hippocampal cultures, we show that the C2A domain is critical for additional steps of vesicular release, including vesicle docking. Optimal vesicle docking and priming is only possible when Munc13 heterodimerizes with RIM via its C2A domain. Beyond being a switching module, our data suggest that the Munc13-RIM heterodimer is an active component of the vesicle docking, priming and release complex

Establishment of a Multi-Analyte Serum Biomarker Panel to Identify Lymph Node Metastases in Non-small Cell Lung Cancer

IntroductionIn non-small cell lung cancer (NSCLC), the presence of locoregional lymph node metastases remains the most important prognostic factor and significantly guides treatment regimens. Unfortunately, currently-available noninvasive staging modalities have limited accuracy. The objective of this study was to create a multianalyte blood test capable of discriminating a patient's true (pathologic) nodal status preoperatively.MethodsPretreatment serum specimens collected from 107 NSCLC patients with localized disease were screened with 47 biomarkers implicated in disease presence or progression. Multivariate statistical algorithms were then used to identify the optimal combination of biomarkers for accurately discerning each patient's nodal status.ResultsWe identified 15 candidate biomarkers that met our criteria for statistical relevance in discerning a patient's preoperative nodal status. A ‘random forest’ classification algorithm was used with these parameters to define a 6-analyte panel, consisting of macrophage inflammatory protein-1α, carcinoembryonic antigen, stem cell factor, tumor necrosis factor-receptor I, interferon-γ, and tumor necrosis factor-α, that was the optimum combination of biomarkers for identifying a patient's pathologic nodal status. A Classification and Regression Tree analysis was then created with this panel that was capable of correctly classifying 88% of the patients tested, relative to the pathologic assessments. This value is in contrast to our observed 85% classification rate using conventional clinical methods.ConclusionsThis study establishes a serum biomarker panel with efficacy in discerning preoperative nodal status. With further validation, this blood test may be useful for assessing nodal status (including occult disease) in NSCLC patients facing tumor resection therapy

Global optimality in k-means clustering

Abstract: We study the problem of finding an optimum clustering, a problem known to be NP-hard. Existing literature contains algorithms running in time proportional to the number of points raised to a power that depends on the dimensionality and on the number of clusters. Published validations of some of these algorithms are unfortunately incomplete; besides, the constant factors (with respect to the number of points) in their running time bounds have seen several published important improvements but are still huge, exponential on the dimension and on the number of clusters, making the corresponding algorithms fully impractical. We provide a new algorithm, with its corresponding complexity-theoretic analysis. It reduces both the exponent and the constant factor, to the extent that it becomes feasible for relevant particular cases. Additionally, it parallelizes extremely well, so that its implementation on current high-performance hardware is quite straightforward. Our proposal opens the door to potential improvements along a research line that had no practical significance so far; besides, a long but single-shot run of our algorithm allows one to identify absolutely optimum solutions for benchmark problems, whereby alternative heuristic proposals can evaluate the goodness of their solutions and the precise price paid for their faster running times