Qualitative behavior of systems of tumor–CD4+–cytokine interactions with treatments

Immunotherapies are important methods for controlling and curing malignant tumors. Based on recent observations that many tumors have been immuno‐selected to evade recognition by the traditional cytotoxic T lymphocytes, we propose mathematical models of tumor–CD4⁺–cytokine interactions to investigate the role of CD4⁺ on tumor regression. Treatments of either CD4⁺ or cytokine are applied to study their effectiveness. It is found that doses of treatments are critical in determining the fate of the tumor, and tumor cells can be eliminated completely if doses of cytokine are large. Bistability is observed in models with either of the treatment strategies, which signifies that a careful planning of the treatment strategy is necessary for achieving a satisfactory outcome. Copyright © 2014 John Wiley & Sons, Ltd.     

Quadruple-layered perovskite (CuCl)Ca2NaNb4O13

We will present the synthesis, structure and magnetic properties of a new quadruple-layered perovskite (CuCl)Ca₂NaNb₄O₁₃. Through a topotactic ion-exchange reaction with CuCl₂, the precursor RbCa₂NaNb₄O₁₃ presumably having an incoherent octahederal tliting changes into (CuCl)Ca₂NaNb₄O₁₃ with a 2a_p×2a_p×2c_p superstructure (tetragonal; a=7.73232(5) Å, c=39.2156(4) Å). The well-defined superstructure for the ion-exchanged product should be stabilized by the inserted CuCl₄O₂ octahedral layers that firmly connect with neighboring perovskite layers. Magnetic studies show the absence of long-range magnetic ordering down to 2 K despite strong in-plane interactions. Aleksandrov′s group theory and Rietveld refinement of synchrotron X-ray diffraction data suggest the structure to be of I4/mmm space group with in-phase tilting along the a and b axes, a two-tilt system (++0).     

Real time automatic detection of Orcinus orca vocalizations in a controlled environment

The use of passive acoustic observation is a useful tool in bioacoustic studies of cetaceans, such as killer whales (Orcinus orca). Such studies require the recording, detection, and classification of vocalizations of animals during long periods of time. The manual processing of the recordings is an extremely time consuming task because of the large amount of data to process. Automatic detection and classification techniques are useful to improve the processing, increase the amount of information and, as a consequence, provide information for the conservation of these species.The Orca Ocean facilities of Loro Parque in the Canary Islands, Spain, were used as an experimental platform for developing devices to perform bioacoustic studies. Detection methods with low computational complexity were tested in order to capture vocalizations of four O. orca specimens in real time. The algorithms were also tested in other scenarios in order to determine their global performance. The sensitivity to noise was also tested. The most accurate method in this study was implemented and integrated with a continuous recording system generating an event database in real time, downsizing the storage demand to 7%. This allowed the storage of all the sound events produced in about one month on a standard computer harddisk and the generation of basic statistics on vocal activity of the animals.     

Modular construction of pyrido[24]crown-8-based templates in the self-assembly of cross-linked [n]catenanes

Starting from the versatile 4-bromopyrido[24]crown-8 building block, novel ditopic and tritopic receptors have been synthesized and shown to be appropriate hosts for bis(4-formylbenzyl)ammonium hexafluorophosphate. Association constants (per binding site) for the corresponding [3]- and [4]pseudorotaxanes, assembled from these components, were determined to be 2753  M^?1 and 723  M^?1, respectively. Mechanical bond formation was attempted utilizing dynamic imine bond formation between the formyl groups of the bound dibenzylammonium threads and p-phenylenediamine.