A filter comprises an amplifier circuit arrangement having a signal input (1) and a signal output (8) and a coupling (36) between a point (37) on a signal path (39) to the signal input and a point (38) on a signal path from the signal output. The amplifier circuit arrangement comprises an inverting amplifier (6) to the input (5) of which the signal input (1) is connected via a series impedance (7), e.g. a resistor. A feedback impedance (9), e.g. a capacitor, connects the amplifier output (8) to ...

A grating spectrometer employing digital control of an oscillating component (a mirror) and phase-locked digital recording of the intensity profile within the narrow spectral domain defined by an oscillation frequency. Flexible choice of oscillation frequency permits measurement in a quiet region of the noise spectrum. Reference waveforms acquired with the same insturment can be stored and later used to deconvolute a more complex spectrum. The use of multiple detector/slit combinations along a R...

An active filter comprises: A. a transmission line and a common, the line having an input side and an output side, B. first and second parallel paths each connected between the transmission line and the common, each path including series connected resistance and capacitance elements, and C. at least two amplifiers associated with each path, each amplifier having input and output terminals connected with different points along said path.

An active band-reject filter of the state-variable type is tuneable over a broad frequency range (three decades) while maintaining a substantial notch depth (50-80 db) which is essentially independent of component value or matching. The filter uses active amplifiers in the inverting mode only, to thereby enable use of inexpensive amplifiers which can be feed-forward compensated to increase their open loop gain and bandwidth. Low-pass, band-pass, and high-pass outputs are also provided, with the ...

An improved filtering circuit connected to the inverting terminal of an operational amplifier having connected in parallel a first resistor and three series capacitors. Two series resistors are connected in parallel with the center capacitor and the junction between the two series resistor is connected to a fixed potential.

A voltage signal rectifier produces a rectified voltage signal from an input offset voltage signal. The voltage signal rectifier includes input offset, output, and reference nodes, two actively controlled current regulation elements (ACCREs), and two controllers. The input offset node is coupled to the input offset voltage signal. The rectified voltage signal is generated onto the output node. The reference node is coupled to a reference voltage for the input offset and rectified voltage signals...

An active phospholipid of the formula ##STR1## wherein R.sub.1 is aliphatic of 14 to 24 carbon atoms saturated or containing 1 or 2 unsaturations, R.sub.3 is a residue selected from the group consisting of choline, ethanolamine, glycerol, serine, inositol, ethanol, n-propanol, n-butanol and ethylene glycol and ##STR2## is an active group in the 2-position of the glycerol released by phospholipases and cosmetic and dermatological compositions containing the same useful for treating or caring for ...

A compound of formula (I) or a pharmaceutically acceptable salt thereof: ##STR1## wherein all the symbols are defined in the specification; having pharmacological activity, including blood pressure lowering activity, a process and intermediates for their preparation and their use as pharmaceuticals.

An active cannula which does more than merely maintain a passage is usable to create and/or enlarge a passage, to position a scope or instrument, to move or locate tissue, etc. The cannula can vary in size or shape as needed, intraoperatively. Because a cannula of the present invention is expandable, the surgeon can make a relatively small incision, stretch the tissue with the expandable cannula, contract the cannula and remove it, allowing the skin to come back to its unstretched condition. Thu...

Interconnection assemblies which adjust their alignment and performance through the use of control feedback from the data transferred through the assemblies.