Philips

About: Philips is a company organization based out in Vantaa, Finland. It is known for research contribution in the topics: Signal & Layer (electronics). The organization has 68260 authors who have published 99663 publications receiving 1882329 citations. The organization is also known as: Koninklijke Philips Electronics N.V. & Royal Philips Electronics.

Rapid selection using G418 of high copy number transformants of Pichia pastoris for high-level foreign gene expression.

Abstract: Pichia pastoris is a methylotrophic yeast increasingly important in the production of therapeutic proteins. Expression vectors are based on the methanol-inducible AOX1 promoter and are integrated into the host chromosome. In most cases high copy number integration has been shown to be important for high-level expression. Since this occurs at low frequency during transformation, we previously used DNA dot blot screens to identify suitable clones. In this paper we report the use of vectors containing the Tn903 kanr gene conferring G418-resistance. Initial experiments demonstrated that copy number showed a tight correlation with drug-resistance. Using a G418 growth inhibition screen, we readily isolated a series of transformants, containing progressively increasing numbers (1 to 12) of a vector expressing HIV-1 ENV, which we used to examine the relationship between copy number and foreign mRNA levels. Northern blot analysis indicated that ENV mRNA levels from a single-copy clone were nearly as high as AOX1 mRNA, and increased progressively with increasing copy number so as to greatly exceed AOX1 mRNA. We have also developed protocols for the selection, using G418, of high copy number transformants following spheroplast transformation or electroporation. We anticipate that these protocols will simplify the use of Pichia as a biotechnological tool.

Electroluminescent display devices

Abstract: An active matrix display device comprises an array of display pixels provided over a common substrate. Each pixel has a voltage-programmed current source circuit, a drive transistor and a light sensitive device for sensing the display element light output. The light sensitive device provides a current dependent on the display element output, and the light sensitive device and the current source circuit define a feedback control loop which controls the voltage provided to the gate of the drive transistor. This pixel circuit uses a current source circuit to provide a gate voltage to a drive transistor. This enables the current source circuit to operate at low current levels, and therefore under low voltage stress.

Fingerprint sensing device and recognition system having predetermined electrode activation

Abstract: A Fingerprint sensing device and a recognition system having a row/column array of sense elements which are coupled to a drive circuit and a sense circuit by sets of row and column conductors, respectively. The sense elements are actively addressable by the drive circuit. Each sense element contains a sense electrode and a switching device (e.g., a TFT) for active addressing of that sense electrode. The sense electrodes of the sense elements are covered by insulating material adapted for receiving, directly thereon or on respective conductive pads overlying the sense electrodes, a finger. Capacitances resulting from individual finger surface portions in combination with sense electrodes are sensed by the sense circuit by applying a potential to the sense electrodes and measuring charging characteristics. In the fingerprint recognition system, an output from the sensing circuit is analyzed and characteristical data is compared with stored characteristical data for identification and verification purposes.

Theoretical study of the Si(100) surface reconstruction

Abstract: We present the results of a systematic study of the reconstruction of the Si(100) surface based upon total energies calculated within the framework of the local-density approximation. We focus on the extent to which total energy differences may be calculated reliably by examining these differences for the ideal surface and four proposed reconstructions: p(2\ifmmode\times\else\texttimes\fi{}1) symmetric, p(2\ifmmode\times\else\texttimes\fi{}1) asymmetric, p(2\ifmmode\times\else\texttimes\fi{}2), and c(4\ifmmode\times\else\texttimes\fi{}2). The calculations were performed using norm-conserving pseudopotentials and a plane-wave basis. The convergence of the total energy differences was assessed by varying the energy cutoff used to truncate the plane-wave basis and the number of sampling points used to perform Brillouin zone (BZ) integrals over a large range. The effect of optimizing atomic geometries as a function of the energy cutoff and density of BZ sampling points was determined. With the exception of the p(2\ifmmode\times\else\texttimes\fi{}2) and c(4\ifmmode\times\else\texttimes\fi{}2) reconstructions, whose energies only differ by 3 meV per dimer, we are able to unambiguously determine the energy ordering of the five systems studied. Disagreements between previous calculations can be largely understood in terms of the different energy cutoffs and BZ samplings used. The electronic structures of the different reconstructions are calculated and compared.

Signal encoding in magnetic particle imaging: properties of the system function

Abstract: Magnetic particle imaging (MPI) is a new tomographic imaging technique capable of imaging magnetic tracer material at high temporal and spatial resolution. Image reconstruction requires solving a system of linear equations, which is characterized by a "system function" that establishes the relation between spatial tracer position and frequency response. This paper for the first time reports on the structure and properties of the MPI system function. An analytical derivation of the 1D MPI system function exhibits its explicit dependence on encoding field parameters and tracer properties. Simulations are used to derive properties of the 2D and 3D system function. It is found that for ideal tracer particles in a harmonic excitation field and constant selection field gradient, the 1D system function can be represented by Chebyshev polynomials of the second kind. Exact 1D image reconstruction can thus be performed using the Chebyshev transform. More realistic particle magnetization curves can be treated as a convolution of the derivative of the magnetization curve with the Chebyshev functions. For 2D and 3D imaging, it is found that Lissajous excitation trajectories lead to system functions that are closely related to tensor products of Chebyshev functions. Since to date, the MPI system function has to be measured in time-consuming calibration scans, the additional information derived here can be used to reduce the amount of information to be acquired experimentally and can hence speed up system function acquisition. Furthermore, redundancies found in the system function can be removed to arrive at sparser representations that reduce memory load and allow faster image reconstruction.