656 results about "Excitation pulse" patented technology

A fluid status monitoring system for use in implantable cardiac stimulation or monitoring devices is provided for monitoring changes in thoracic fluid content. A fluid status monitor includes excitation pulse generating and control circuitry, and voltage and current measurement and control circuitry for performing a series of cardiac-gated, intra-thoracic impedance measurements. The cardiac-gated measurements are filtered or time-averaged to provide a fluid status impedance value, with respiratory noise removed. Based on comparative analysis of the fluid status impedance value, a clinically relevant trend in fluid status may be tentatively diagnosed and a fluid status response provided. Cross-check intra-thoracic impedance measurements performed using the same or a different excitation pathway and a different measurement pathway than the primary intra-thoracic impedance measurement configuration may be used to verify a tentative diagnosis.

A method for acquiring an image or spectrum of a subject or object residing within the magnetic field of a magnetic resonance apparatus, comprises the steps of:

• • executing a predetermined pulse sequence for applying gradient magnetic fields and for coupling in electromagnetic excitation pulses to induce nuclear magnetic resonance within the subject or object;
  • detecting an electromagnetic signal resulting from said magnetic resonance; and
  • constructing at least one image or magnetic resonance spectrum of said subject or object from said detected electromagnetic signal.

According to the invention, said coupling in of the electromagnetic excitation pulse and/or said detecting of the electromagnetic signal are carried out substantially by means of travelling electromagnetic waves.

A system comprising a solid state lattice containing an electronic spin coupled to a nuclear spin; an optical excitation configuration which is arranged to generate first optical radiation to excite the electronic spin to emit output optical radiation without decoupling the electronic and nuclear spins; wherein the optical excitation configuration is further arranged to generate second optical radiation of higher power than the first optical radiation to decouple the electronic spin from the nuclear spin thereby increasing coherence time of the nuclear spin; a first pulse source configured to generate radio frequency (RF) excitation pulse sequences to manipulate the nuclear spin and to dynamically decouple the nuclear spin from one or more spin impurities in the solid state lattice so as to further increase the coherence time of the nuclear spin; a second pulse source configured to generate microwave excitation pulse sequences to manipulate the electronic spin causing a change in intensity of the output optical radiation correlated with the electronic spin and with the nuclear spin via the coupling between the electronic spin and the nuclear spin; and a detector configured to detect the output optical radiation correlated with the electronic spin and the nuclear spin so as to detect a nuclear spin state of the nuclear spin.

A wireless sensor reader is provided to interface with a wireless sensor. The wireless sensor reader transmits a narrowband, fixed frequency excitation pulse to cause the wireless sensor to generate a ring signal. The ring signal corresponds to the value of the physical parameter being sensed. The wireless sensor reader receives and amplifies the ring signal and sends the signal to a phase-locked loop. A voltage-controlled oscillator in the phase-locked loop locks onto the ring signal frequency and generates a count signal at a frequency related to the ring signal frequency. The voltage-controlled oscillator is placed into a hold mode where the control voltage is maintained constant to allow the count signal frequency to be determined. The low power, simple circuitry required to generate the excitation pulse allows the reader to be a small, battery operated unit. Alternative methods of frequency determination are also disclosed.

A luminescent probe marking is excited with at least one excitation pulse of at least one excitation source. The probe intensity values of emission intensity from emission radiation of the luminescent probe marking are measured in response to the excitation pulse(s) at time intervals. A probe intensity-versus-time emission function is formed of the probe intensity values, and the probe intensity-versus-time emission function is compared with at least one reference intensity-versus-time emission function after the probe intensity-versus-time emission function and the reference intensity-versus-time emission function have been normalized.

NMR spin echo signals, acquired on a MWD logging tool, are susceptible to errors magnetic flux density has a gradient and the magnet on the logging tool is moving relative to the earth. The errors can be corrected by having the excitation pulse cover a smaller or a larger volume than the refocusing pulses. Correction may also be made by selective saturation, or by echo averaging.

A system composed of multiple transmit coils with corresponding RF pulse synthesizers and amplifiers is disclosed. A method of designing RF pulses specific to each transmit coil to induce spatiotemporal variations in a composite B₁ field is also disclosed. The present invention supports faithful production of desired excitation profiles and accommodates the use of any coil array geometry. The present invention also supports reduction in excitation pulse length. Through effective B₁ field maps for each transmit coil, mutual coupling and other inter-coil correlations are accounted for in the RF pulse design.

In a method and a control device for operating a magnetic resonance imaging system, initially, in a sequence module, multiple slices are excited in an examination object by respective spatially selective RF slice excitation pulses whereby the time between two consecutive of these RF slice excitation pulses defines a first time interval. A preparation block follows the last excitation pulse. The preparation bloc radiates at least one RF refocusing pulse designed so that, for each of the slices, one echo signal is formed. The time interval between two consecutive echo signals is equal to the first time interval. Then, a second RF refocusing pulse is emitted at a second time interval after the last echo signal formed by the preparation block. The second RF refocusing pulse is designed so that, for each of the slices, one further echo signal is formed, and the time interval of two consecutive echo signals is equal to the first time interval. Subsequently, at least one further RF refocusing pulse is emitted at a third time interval after the preceding RF refocusing pulse for producing a number of temporally separated echo signals per refocusing pulse. The third time interval is selected so that the number of echo signals per RF refocusing pulse is twice as high as the number of excited slices.

Systems and methods for closed loop spinal cord stimulation are provided. The systems and methods position a first electrode proximate to a dorsal column. The first electrode is electrically coupled to an implantable pulse generator (IPG). The systems and methods further program the IPG to deliver excitation pulses to the first electrode based on a stimulation level. The excitation pulses are emitted from the first electrode. The systems and methods further position a second electrode proximate to a dorsal root. The second electrode is electrically coupled to the IPG. The systems and methods further measure at the second electrode a first evoked potential waveforms resulting from the excitation pulses.

A method and system are disclosed for NMR echo-train data acquisition and processing for enhanced tracking of the error in the signal due to magnetoacoustic effects, known as ringing, that are not cancelled out or otherwise corrected. In one aspect, the method enables correction of ringing signals in a single pass by way of collecting a composite signal that includes echoes due to pulses at least at two different frequencies. The choice of one or more of the frequencies, the phase of the pulses, and the recovery period enable cancellation of the ringing signal from the echoes, including the echo from an excitation pulse. In another aspect, the method encompasses providing protection against errors due to tool motion by saturating a relatively wide sensitive region with the echo signals collected from within this relatively wide sensitive signal. Preferred embodiments of the invention include one or more of the aforementioned aspects.

A method and system are presented for producing an output coherent anti-stokes Raman scattering (CARS) signal of a medium. The method comprises generation of a unitary optical excitation pulse that carries a pump photon, a Stokes photon and a probe photon; and inducing a CARS process in the medium by exciting the medium by the at least one such unitary optical excitation pulse.

A time-resolved fluorescence device is described for the detection and diagnosis of various metabolic diseases in a noninvasive or minimally invasive manner. The device uses an ultra-short excitation pulse that comprises of a repetition of nanosecond pulses. The excitation pulse is directed incident onto a strategically selected area of the patient body such as the forearm, the feet, and the palm. This light interacts with the different layers of the skin. The absorbed light excites conditions of interest in the skin, which in turn generate a fluorescence signal, which is collected by a detector. A processor is coupled to the detector to measure the transient fluorescence intensity decay of the skin in terms of lifetimes, and the contribution of individual fluorophores to the overall fluorescence signal.

In a magnetic resonance tomography apparatus employing a FISP pulse sequence, the pulse sequence is repeated with a repetition time T_R with different phase-coding gradient directions and with an alternating operational sign of the flip angle α. The gradient pulse trains are thereby completely balanced. A phase increment ΔΦ=β is generated in addition to the alternating operational sign of the flip angle α between successive excitation pulses, so that the steady state signals for a first and a second spin ensemble optionally have either identical or reversed signal polarities. A first dataset on the basis of identical signal polarities and a second dataset on the basis of reversed signal polarities are obtained by means of the free selection of the mutual signal polarities. A pure image of the first and the second spin ensembles is thus obtained by the addition and/or subtraction of the first and second datasets.

A loop-gap resonator for providing an excitation pulse in a down hole nuclear magnetic resonating (NMR) tool for determining a parameter of interest in a formation adjacent a borehole. The loop-gap resonator is constructed having one or more capacitive gaps formed in a nonmagnetic conductive loop. The loop-gap resonator may be deployed down a bore in a measurement while drilling (MWD) configuration or in a wire line configuration. The MWD configuration may utilize a non-rotating sleeve rotationally associated with the drill string.

The invention belongs to the technical field of fluorescence immunoassay and relates to a photon counting multi-channel time-resolved fluorescence immunoassay system which comprises a light source module, a detection module and a time marked photon counting analysis/control module. At the same time, the invention relates to a counting method adopted by the system. The counting method of exciting a sample to be detected with pulse light, sending a fluorescence signal generated by the sample after excitation into a PMT (Photo Multiplier Tube) photon counting head and outputting a pulse signal comprises the following steps of taking cycles of the excitation pulse light as counting cycles, dividing each counting cycle into a plurality of time intervals with the same width, accumulating photons detected after sending excitation light pulses of each counting cycle into a memory corresponding to a corresponding time window, that is marking the positions of the photons in the pulse cycles with the intervals where the time windows are located, and uploading data in the memory into an upper computer after counting for the cycles. The multi-channel time-resolved fluorescence immunoassay system is low in cost and has very high sensitivity.

An objective oriented NMR logging method selects pulse sequences over a plurality of frequencies from a set of building blocks. The building blocks include trainlet sequences wherein each trainlet comprises an excitation pulse and a plurality of refocusing pulses, the total length of a trainlet being typically less than 10 ms. Another building block is a short CPMG or modified CPMG sequence and yet another building block is a regular CPMG or modified CPMG sequence. The modified CPMG sequences may have refocusing pulses with a tipping angle less than 180° to reduce the power consumption. Based on the logging objective (formation evaluation or FE, FE plus hydrocarbon typing, FE plus gas evaluation) the building blocks are combined at a plurality of frequencies with different wait times and TEs.

In a magnetic resonance method and apparatus to generate images by a parallel acquisition technique an excitation pulse is radiated into an examination subject, and a first echo train is generated after the excitation pulse, wherein the first echo train densely scans a segment of k-space to be scanned for an acquisition of coil calibration data. Coil calibration data are acquired by means of the first echo train. The acquired coil calibration data are stored in a coil calibration data set. A second echo train is generated after the same excitation pulse, wherein the second echo train undersamples a segment of k-space to be scanned for an acquisition of image data. Image data are acquired by means of the second echo train. The acquired image data are stored in an incomplete image data set. An image data set is generated by substituting data missing in the incomplete image data set due to the undersampling by means of a selected PAT reconstruction technique using the coil calibration data.

Methods for detecting a liquid under a surface and characterizing Ice are provided The liquid may be a liquid hydrocarbon such as crude oil or fuel oil or mineral oil The surface may be ice, snow, or water, and the method may be practiced in an arctic region to detect oil spills, leaks, or seepages The methods may be used with a range finder to characterize marine ice The methods may include a nuclear magnetic resonance (NMR) tool with antenna to send a radio-frequency (RF) excitation pulse or signal into volume of substances being detected, detect an NMR response signal to determine the presence of the liquid of interest The NMR response may include a relaxation time element and an intensity level and may include a free induction signal (T2*), a spin echo signal (T2), a train of spin echo signals (T2), or a thermal equilibrium signal (T 1).

An analog preamplifier measurement system for a microphone array builds on conventional microphone arrays by providing an integral “self-calibration system.” This self-calibration system automatically injects an excitation pulse of a known magnitude and phase to all preamplifier inputs within the microphone array. The resulting analog waveform from each preamplifier output is then measured. A frequency analysis, such as, for example, a Fourier or Fast Fourier Transform (FFT), or other conventional frequency analysis, of each of the resulting waveforms is then performed. The results of this frequency analysis are then used to automatically compute frequency-domain compensation gains (e.g., magnitude and phase gains) for each preamplifier for matching or balancing the responses of all of the preamplifiers with each other.

The invention discloses a de-acidifying method for paper cultural relics, which comprises the following steps of: 1) flatly spreading acidified paper cultural relics on a flat board; 2) injecting an ion source reagent including OH- and Ca<2+> into a bubbler, and importing a mixed gas of helium gas and nitrogen to serve as a carrier gas, and transmitting the ion source reagent to a plasma spray gun; 3) turning on a plasma excitation pulse power source, forming ion flames containing OH- and Ca<2+> at the muzzle of the plasma spray gun; and spraying the ion flames to scan the surface of the flattened paper cultural relics to perform deacidifying processing. In the method disclosed by the invention, a plasma discharging form is adopted under normal temperature and normal pressure work conditions, thereby complex and expensive vacuum equipment are avoided being used, and damages of an aqueous solution infusion method to a paper body are avoided; and the method disclosed by the invention can be used for realizing rapid large-area deacidifying processing and has the advantages of uniformity for de-acidification, stable process, and suitability for industrialized large-scale production.

MR spectroscopy and imaging method for imaging pulmonary and cardiac vasculature and the cardiac region and evaluating blood flow or circulatory deficits use dissolved phase polarized 129Xe gas and large flip angle excitation pulses. Pulmonary and cardiac vasculature MRI images are obtained by delivering gas to a patient via inhalation such as with a breath-hold delivery-procedure, exciting the dissolved phase gas with a large flip angle pulse, and generating a corresponding image. Preferably, the image is obtained using multi-echo imaging techniques. Blood flow is quantified using low field MR spectroscopy and an RF excitation pulse with a frequency which corresponds to the resonance of the dissolved phase 129Xe.

A transmitter for pilot tone navigation in a magnetic resonance tomography system includes a power supply and an antenna. The transmitter is configured to transmit a pilot tone signal via the antenna. The transmitter also includes a decoupling element in order to protect a transmitter output from signals that the antenna receives with excitation pulses of the magnetic resonance tomography system during a magnetic resonance tomography. In a method, movement-dependent changes to the pilot tone signal of the transmitter are identified by a controller of the magnetic resonance tomography system.