Isolation and characterization of human placental chorionic villar extracellular matrix

The cell-free extracellular matrix of human placental chorionic villi has been prepared by a procedure employing extraction of the terminal villar fragments with the detergents Triton X-100 and sodium deoxycholate. The isolated human placental extracellular matrix retains an intact, but collapsed, histoarchitecture, as observed by scanning and transmission electron microscopy. It remains intact, in large part because of the presence of continuous sheets of villar basement membranes and associated interstitial collagen fibers and scattered patches of fibrin. The staining charcteristics and chemical composition of the isolated human placental extracellular matrlix are similar to those reported for basement membranes in several tissues and indicate the presence of collagen-like and glycoprotein components in this preparation. Gel electrophoresis of urea-SDS-mercaptoethanol extracts of the matrix showed that it consists of several polypeptide components of various molecuar weights, some of which are associated into high molecular weight complexes by disulfide bonds.     

Fundamentals of testability-a tutorial

A review is presented of electrical testing, failure mechanisms, fault models, fault simulation, testability analysis, and test-generation methods for CMOS VLSI circuits. The relationships between the most commonly used fault models are explored. Various fault simulation methods are contrasted. The basic mechanisms used in test-vector generation are illustrated by examples. The importance of testability analysis as a guide to design and test generation is discussed. Algorithms for automatic test-pattern generation are summarized     

A pressure controller for estimating parameters for a nonlinear CSFmodel

Pressure feedback control of cerebrospinal fluid (CSF) infusion rate was used to estimate the parameters of a nonlinear model of the CSF system. The steady-state pressure and infusion rate were used to estimate the parameters of CSF formation and CSF absorption using the nonlinear least-squares method. The CSF compliance was then estimated using the transient portion of the pressure/infusion rate responses     

Dimer pair correlations on the brick lattice

Using exact methods, pair-correlation functions are studied in the dimer model defined on a brick lattice. At long distances these functions exhibit strongly anisotropic algebraic decay and, near criticality, the length scales diverge differently in the two principal directions. The critical exponents are _x=1/2 and _y=1. These results are in agreement with deductions drawn from recent exact finite-size scaling calculations. We also interpret our results in the light of domain wall theories of commensurate-incommensurate transitions, and in particular we study the relation of the present model to the discrete version of the Pokrovsky-Talapov model introduced by Villain.     

Metal-metal bonding in tetracyanometalates (M=PtII, PdII, NiII) of monovalent thallium. Crystallographic and spectroscopic characterization of the new compounds Tl2Ni(CN)4 and Tl2Pd(CN)4

The new crystalline compounds Tl2Ni(CN)4 and Tl2Pd(CN)4 were synthesized by several procedures. The structures of the compounds were determined by single-crystal X-ray diffraction. The compounds are isostructural with the previously reported platinum analogue, Tl2Pt(CN)4. A new synthetic route to the latter compound is also suggested. In contrast to the usual infinite columnar stacking of [M(CN)4]2- ions with short intrachain M-M separations, characteristic of salts of tetracyanometalates of NiII, PdII, and PtII, the structure of the thallium compounds is noncolumnar with the two TlI ions occupying axial vertices of a distorted pseudo-octahedron of the transition metal, [MTl2C4]. The Tl-M distances in the compounds are 3.0560(6), 3.1733(7), and 3.140(1) A for NiII, PdII, and PtII, respectively. The short Tl-Ni distance in Tl2Ni(CN)4 is the first example of metal-metal bonding between these two metals. The strength of the metal-metal bonds in this series of compounds was assessed by means of vibrational spectroscopy. Rigorous calculations, performed on the molecules in D4h point group symmetry, provide force constants for the Tl-M stretching vibration constants of 146.2, 139.6, and 156.2 N/m for the NiII, PdII, and PtII compounds, respectively, showing the strongest metal-metal bonding in the case of the Tl-Pt compound. Amsterdam density-functional calculations for isolated Tl2M(CN)4 molecules give Tl-M geometry-optimized distances of 2.67, 2.80, and 2.84 A for M = NiII, PdII, and PtII, respectively. These distances are all substantially shorter than the experimental values, most likely because of intermolecular Tl-N interactions in the solid compounds. Time-dependent density-functional theory calculations reveal a low-energy, allowed transition in all three compounds that involves excitation from an a1g orbital of mixed Tl 6pz-M ndz2 character to an a2u orbital of dominant Tl 6pz character.     

Understanding linearity in wireless communication amplifiers

This paper investigates the linearity of active devices and amplifiers that have modulated input signals. We describe an implementation of a mathematical technique for calculating spectral regrowth due to the nonlinear amplification of modulated signals typically used in wireless communication systems. This technique only requires knowledge of the single-tone gain and phase data as a function of input power and can be applied to any modulated signal given (a) the device or amplifier characteristics do not change significantly over the bandwidth of the input signal and (b) the modulation frequencies are much less than the carrier frequency. Verification of the mathematical technique is presented using examples of measured and calculated spectra for π/4-differential quadrature phase shift keying (DQPSK) personal handy phone system (PHS) and code division multiple access (CDMA) Offset-QPSK personal communication system (PCS) modulation schemes. This calculation technique is essential in determining fundamental tradeoffs between device performance (linearity, output power, gain, and power-added efficiency) and device bias conditions and load impedance