1,454 research outputs found
RELATION BETWEEN WATER PERMEABILITY AND INTEGRITY OF SULFHYDRYL GROUPS IN MALIGNANT AND NORMAL CELLS
When malignant cells, animal and human, were exposed in vitro to solutions of heavy metals or other selected compounds, three types of cell blebs were produced: (1) acentric blebs, arising from one side of the cell, e. g., by chlormerodrin, meralluride sodium, mercuric chloride; (2) symmetrical blebs; which completely enveloped the cell, e. g., by strong silver protein, auric chloride, p-chloromercuribenzoate; (3) scallop blebs, numerous small spherical elevations which completely covered the cell, e.g., by N-ethyl-maleimide, trivalent arsenicals, iodoacetamide. As indicated by vital stains and morphologic appearance, the blebs arose in healthy cells. They also can be made to appear in vivo in ascites tumor cells by intraperitoneal administration of a blebbing agent. All the bleb-producing chemicals have the property of reacting with protein-sulfhydryl groups by alkylation, oxidation or mercaptide formation. The three bleb types have been induced in 8 mouse and 2 rat ascites tumor cells; in 4 human and 1 mouse malignant cell lines; and in 3 normal cell lines grown in tissue culture. In contrast, cells from normal solid tissues of liver, lung, spleen, kidney, testis and brain from mouse, rat and rabbit failed to produce blebs. A possible interpretation for these observations is presented
Transverse instabilities of multiple vortex chains in superconductor-ferromagnet bilayers
Using scanning tunneling microscopy and Ginzburg-Landau simulations we
explore vortex configurations in magnetically coupled NbSe-Permalloy
superconductor-ferromagnet bilayer. The Permalloy film with stripe domain
structure induces periodic local magnetic induction in the superconductor
creating a series of pinning-antipinning channels for externally added magnetic
flux quanta. Such laterally confined Abrikosov vortices form quasi-1D arrays
(chains). The transitions between multichain states occur through propagation
of kinks at the intermediate fields. At high fields we show that the system
becomes non-linear due to a change in both the number of vortices and the
confining potential. The longitudinal instabilities of the resulting vortex
structures lead to vortices `levitating' in the anti-pinning channels.Comment: accepted in PRB-Rapid
Computer-Aided Design of Microwave-Photonics-Based RF Circuits and Systems
In the process of design, a developer of new microwave-photonics-based RF apparatuses is facing a problem of choosing appropriate software. As of today, the existing optical and optoelectronic CAD tools (OE-CAD) are not developed like CAD tools intended for modeling of RF circuits (E-CAD). On the contrary, operating at symbolic level, modern high-power microwave E-CAD tools simply and with high precision solve this problem, but there are no models of active photonic components in their libraries. To overcome this problem, we proposed and validated experimentally a new approach to model a broad class of promising analog microwave radio-electronics systems based on microwave photonics technology. This chapter reviews our known, updated, new models and simulation results using microwave-electronics off-the-shelf computer tool NI AWRDE to pursue advanced performances corresponding to the last generation of key photonics structural elements and important RF devices on their basis
Non-Redundant Spectral Dimensionality Reduction
Spectral dimensionality reduction algorithms are widely used in numerous
domains, including for recognition, segmentation, tracking and visualization.
However, despite their popularity, these algorithms suffer from a major
limitation known as the "repeated Eigen-directions" phenomenon. That is, many
of the embedding coordinates they produce typically capture the same direction
along the data manifold. This leads to redundant and inefficient
representations that do not reveal the true intrinsic dimensionality of the
data. In this paper, we propose a general method for avoiding redundancy in
spectral algorithms. Our approach relies on replacing the orthogonality
constraints underlying those methods by unpredictability constraints.
Specifically, we require that each embedding coordinate be unpredictable (in
the statistical sense) from all previous ones. We prove that these constraints
necessarily prevent redundancy, and provide a simple technique to incorporate
them into existing methods. As we illustrate on challenging high-dimensional
scenarios, our approach produces significantly more informative and compact
representations, which improve visualization and classification tasks
Efficient Terahertz Generation in Triply Resonant Nonlinear Photonic Crystal Microcavities
We propose a scheme for efficient cavity-enhanced nonlinear THz generation
via difference-frequency generation (DFG) processes using a triply resonant
system based on photonic crystal cavities. We show that high nonlinear overlap
can be achieved by coupling a THz cavity to a doubly-resonant,
dual-polarization near-infrared (e.g. telecom band) photonic-crystal nanobeam
cavity, allowing the mixing of three mutually orthogonal fundamental cavity
modes through a chi(2) nonlinearity. We demonstrate through coupled-mode theory
that complete depletion of the pump frequency - i.e., quantum-limited
conversion - is possible in an experimentally feasible geometry, with the
operating output power at the point of optimal total conversion efficiency
adjustable by varying the mode quality (Q) factors.Comment: 8 pages, 3 figure
User interfaces for information systems
This paper presents descriptions of four information-system interface projects in progress at ESRIN, each demonstrating a somewhat different approach to interface design, but ali sharing the commonality of responding to user goals, tasks and characteristics. It is suggested that next-generation scientific information systems will have to be designed for direct access by end users to a large variety of information sources, through a commom interface. Design of such systems, including their interfaces, should be based on a multi-level analysis of user goals, tasks and domain views.Se describen cuatro proyectos de interfaces de sistemas de información que se están desarrollando en ESRIN (establecimiento de la Agencia Espacial Europea, en Frascati). Cada uno de ellos muestra un enfoque diferente del diseño de interfaces, pero todos tienen en común el responder a los objetivos, tareas y caracterÃsticas de los usuarios. Se sugiere que la próxima generación de sistemas de información cientÃfica se tendrá que diseñar para permitir el acceso directo de los usuarios finales a una gran variedad de fuentes de información a través de una interfaz común. El diseño de tales sistemas y de sus interfaces deberÃa basarse en un análisis multinivel de objetivos, tareas y puntos de vista propios de la materia de trabajo de cada usuario
Automated user modeling for personalized digital libraries
Digital libraries (DL) have become one of the most typical ways of accessing any kind of digitalized information. Due to this key role, users welcome any improvements on the services they receive from digital libraries. One trend used to
improve digital services is through personalization. Up to now, the most common approach for personalization in digital libraries has been user-driven. Nevertheless, the design of efficient personalized services has to be done, at least in part, in
an automatic way. In this context, machine learning techniques automate the process of constructing user models. This paper proposes a new approach to construct digital libraries that satisfy user’s necessity for information: Adaptive Digital Libraries, libraries that automatically learn user preferences and goals and personalize their interaction using this information
Reaction of methylphenylselenuranylidene derivatives of dimedon and dibenzoylmethane with triphenylphosphine and tris(dimethylamino)phosphine
Triphenylphosphine and tris (dimethylamino)phosphine demethylate 2-methylphenylselenuranylidenedimedon and methylphenylselenuranylidenedibenzoylmethane to give the corresponding enolate-anion of phosphonium salts. © 1980 Plenum Publishing Corporation
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