Analysis on motion of Earth’s center of mass observed with CHAMP mission

Geocenter motion (GCM) is one important topic for constructing and maintaining the terrestrial reference frame and its applications. GCM is studied from CHAMP with the multi-step approach in this paper. Geometric orbits of CHAMP in 2001–2006 are precisely determined with the kinematic method only from the satellite-borne GPS zero-difference data. Then a GCM time series is estimated from the precise kinematic orbits based on the theory of satellite dynamics to fit the CHAMP’s real geometric orbits. We compare the series with the geocenter series used in ITRF2005. Then the GCM series are analyzed with Fourier transform and wavelet transformation. The mean motions within 6 years in TX, TY and TZ directions are respectively 0.8 mm, 2.2 mm, and 7.9 mm. The trends of GCM in the three directions are 0.495 mm/a, −0.004 mm/a, and 1.309 mm/a, respectively. The long-term movement (2001–2006) indicates that the crustal figure is changing. The seasonal variations are the main component which may be excitated by the mass redistribution of Earth’s fluid layer, e.g. ocean, atmosphere and continental water. The inter-annual variations are also found in the GCM series measured with CHAMP. Supported by the International S&T Cooperation Program of China (Grant No. 2006DFA21980), the National Hi-tech R&D Program of China (Grant No. 2006AA12z303), the National Natural Science Foundation of China (Grant No. 40774009), and the Natural Science Foundation of Shandong Province, China (Grant No. Y2003E01)     

Cloning and functional characterization of a Caenorhabditis elegans muscarinic acetylcholine receptor

A cDNA clone encoding a muscarinic acetylcholine receptor (mAChR) has been isolated from the nematode Caenorhabditis elegans. The nematode mAChR, consisted of 585 amino acids, displays a high degree of amino acid sequence homology to other invertebrate and vertebrate mAChRs. Excluding a highly variable middle portion of the third intracellular loop, the C. elegans mAChR shares about 51% amino acid sequence identity with a Drosophila mAChR and 42-44% identity with human m1-m5 mAChR subtypes. Comparison of the cDNA sequence with the corresponding genomic sequence reveals that the C. elegans mAChR gene contains ten introns, eight of them in the coding region. Pharmacological profiles of the C. elegans mAChR expressed in Chinese hamster ovary (CHO) cells were shown to be similar to those of mammalian counterparts, indicating that ligand binding domains of the receptor have been conserved during evolution. When this cloned receptor was expressed in Xenopus oocytes, acetylcholine evoked a transient Cl- current. Furthermore, activation of the receptor with oxotremorine, acetylcholine or carbachol resulted in the stimulation of phosphatidylinositol metabolism in CHO cells, suggesting that the receptor is coupled to phospholipase C activation.     

A vertical-type a-Si:H back-to-back Schottky diode for high-speedcolour image sensor

A glass/ITO/a-Si:H/Cr photodiode with a voltage selectable spectral response was fabricated. The diode consists of two back-to-back Schottky junctions. As the bias at the Cr side changes from 1.5 to -1.5 V, three color peak responses can be found, i.e., 480 nm (blue) at V =0.5 V, 530 nm (green) at 1.5 V, and 620 nm (red) at -1.5 V. The basic idea consists of using the different bias voltages to change the location and depth of the photon collection region in which photons with different wavelengths are mainly collected. The photoresponse time was measured under a red LED light injection with an intensity of 150 μW. The typical photoresponse time for red is 60 ns under -1.5-V bias. These basic studies show that the vertical-type Cr/a-Si:H/ITO back-to-back Schottky diode is a good candidate for a high-speed colour image sensor     

Quasi-optical integrated antenna and receiver front end

A quasioptical receiver front end applicable to both microwave and millimeter-wave receiver arrays is presented. Two planar microwave integrated circuit (MIC) quasioptical receiver circuit designs that integrate a coupled slot antenna, a Schottky-diode balanced mixer, and a local oscillator on the same substrate are described. The even-mode/odd-mode characteristics of the coupled slotlines are used to achieve intrinsic RF/LO and RF/IF isolation. To demonstrate circuit feasibility, X-band scaled models of the circuit unit using a Gunn-diode oscillator on an Epsilam-10 substrate, and MESFET local oscillator on a R/T Duroid substrate were built and tested. Results of these tests are included     

A relaxed primal-dual path-following algorithm for linear programming

In this paper, we provide an easily satisfied relaxation condition for the primaldual interior path-following algorithm to solve linear programming problems. It is shown that the relaxed algorithm preserves the property of polynomial-time convergence. The computational results obtained by implementing two versions of the relaxed algorithm with slight modifications clearly demonstrate the potential in reducing computational efforts.Partially supported by the North Carolina Supercomputing Center, the 1993 Cray Research Award, and a National Science Council Research Grant of the Republic of China.     

A novel β-SiC/Si heterojunction backward diode

In this letter, a novel β-SiC/Si heterojunction backward diode has been developed successfully. The developed new backward diode is somewhat different from a conventional one. The β-SiC thin film was grown by a low pressure rapid thermal chemical vapor deposition (LP-RTCVD) using a SiH₄-C₃H₈-H₂ gas system. Its current-voltage characteristics under different operation temperatures (25-200°C) have been measured. In addition, the curvature coefficient γ has also been calculated and it is found to be insensitive to temperature variation up to 180°C. The operation temperature is the highest reported thus far, to our knowledge     

Aggregation matrix for the reduced-order modified Cauer CFE model

A direct procedure is presented for obtaining the `aggregation matrix? for a reduced-order model obtained by the method of modified Cauer continued-fraction expansion. It does not require that the original state equation be first transformed to companion form.     

A multiplication theorem for balanced howell rotations

The concept of partitionable starters is introduced and it is shown how to construct: a balanced Howell rotation on mn players from a balanced Howell rotation on n players, a balanced Howell rotation on m players, and a partitionable starter on m players. Two results concerning the existence of partitionable starters are proved     

Determination of Trace Iron(II) in the Presence of Iron(III)

The determination of trace iron(II) is usually interfered by the presence of iron(III) when ortho-phenanthroline colorimetric method is used. In this report a chromogenic reagent which contains ortho-phenanthroline-EDTA mixture has been developed to decrease the interference of ferric ion after adjusting the acidity of sample at 0.1 N by adding the sulfuric acid. The procedure is also simplified by introducing sulfamate buffer solution (pH= 1.5) without adjusting the acidity of sample with sulfuric acid. If iron(III) is not present in the sample, this method is also applicable. The comparative results are exhibited for the present method and the conventional o-phenanthroline method.     

A silicon bag model with SU(2) × SU(2) chiral dynamics

We describe a soliton bag model which incorporates explicitly SU(2) × SU(2) chiral dynamics, including the conservation of the polar vector current, the partial conservation of the axial vector current, and the SU(2) × SU(2) current algebra. This model appears to be renormalizable so that higher order effects may be treated systematically.