315 research outputs found
The spectroscopic parameters of sodium cyanide, NaCN (X 1A'), revisited
The study of the rotational spectrum of NaCN (X A') has recently been
extended in frequency and in quantum numbers. Difficulties have been
encountered in fitting the transition frequencies within experimental
uncertainties. Various trial fits traced the difficulties to the incomplete
diagonalization of the Hamiltonian. Employing fewer spectroscopic parameters
than before, the transition frequencies could be reproduced within experimental
uncertainties on average. Predictions of -type -branch transitions with
up to 570 GHz should be reliable to better than 1 MHz. In addition,
modified spectroscopic parameters have been derived for the 13C isotopic
species of NaCN.Comment: 5 pages, no figure, J. Mol. Spectrosc., appeared; CDMS links update
High throughput optical readout of dense arrays of nanomechanical systems for sensing applications
N. F. MartΓnez et al...We present an instrument based on the scanning of a laser beam and the measurement of the reflected beam deflection that enables the readout of arrays of nanomechanical systems without limitation in the geometry of the sample, with high sensitivity and a spatial resolution of few micrometers. The measurement of nanoscale deformations on surfaces of cm2 is performed automatically, with minimal need of user intervention for optical alignment. To exploit the capability of the instrument for high throughput biological and chemical sensing, we have designed and fabricated a two-dimensional array of 128 cantilevers. As a proof of concept, we measure the nanometer-scale bending of the 128 cantilevers, previously coated with a thin gold layer, induced by the adsorption and self-assembly on the gold surface of several self-assembled monolayers. The instrument is able to provide the static and dynamic responses of cantilevers with subnanometer resolution and at a rate of up to ten cantilevers per second. The instrumentation and the fabricated chip enable applications for the analysis of complex biological systems and for artificial olfaction.The authors acknowledge financial support from the
Spanish Science Ministry through Project Nos. TEC2009β
14517-C02, TRA2009β0117, and CSD2007β00010.Peer reviewe
Electrodynamic Model of the Heart to Detect Necrotic Areas in a Human Heart
To diagnose the conditions and diseases of the cardiovascular system is the main task of electrocardiology. The problem of the cardiovascular system diagnostics is caused by a complex multi-level mechanism of its functioning, and only experienced specialists are able to establish a correct diagnosis. Since the working heart is inaccessible to direct observations in real life, diagnostics of diseases is based on noninvasive methods such as electrocardiography. By assumption, weak "bursts" (micropotentials) of electrocardiographic signals in different areas are the precursors of dangerous arrhythmias. The amplitude of these signals on the body surface is insignificant and tends to be commensurate with the noise level of the measuring system. Advances in electrocardiography make it possible to generate a high resolution ECG signal and to detect the heart micropotentials. The method of modeling helps to understand causes of micropotentials in the ECG signal by selecting the model parameters. The model of the heart should allow generating a signal close to the high resolution ECG signal. The research aims to find a numerical model that allows solving the inverse problem of the heart tissue characteristics recovery using a high resolution ECG signal and CT data on the heart geometry. The proposed computer model and highly sensitive methods for the ECG measurement are the part of the hardware-software complex to detect dangerous precursors of cardiac arrhythmias
Cutoff-Free Traveling Wave NMR
Recently, the concept of traveling-wave NMR/MRI was introduced by Brunner et
al. (Nature 457, 994-992 (2009)), who demonstrated MR images acquired using
radio frequency (RF) waves propagating down the bore of an MR scanner. One of
the significant limitations of this approach is that each bore has a specific
cutoff frequency, which can be higher than most Larmor frequencies of at the
magnetic field strengths commonly in use for MR imaging and spectroscopy today.
We overcome this limitation by using a central conductor in the waveguide and
thereby converting it to a transmission line (TL), which has no cutoff
frequency. Broadband propagation of waves through the sample thus becomes
possible. NMR spectra and images with such an arrangement are presented and
genuine traveling wave behavior is demonstrated. In addition to facilitating
NMR spectroscopy and imaging in smaller bores via traveling waves, this
approach also allows one to perform multinuclear traveling wave experiments (an
example of which is shown), and to study otherwise difficult-to-access samples
in unusual geometries.Comment: 25 pages, 7 figures, previously presented at (1) World-Wide NMR
Conference (ISMAR/Ampere joint meeting), Florence, Italy, July 9, 2010, and
(2) Experimental NMR Conference, Asilomar, CA, April 13, 201
Temporal and spatial analysis of fields generated by eddy currents in superconducting magnets: Optimization of corrections and quantitative characterization of magnet/gradient systems
ΠΡΡΡΠΎΡΡΠΈΠ½Π³ Π² Π±ΡΡΠ΅Π½ΠΈΠΈ ΠΈ ΠΊΠ°ΠΏΠΈΡΠ°Π»ΡΠ½ΠΎΠΌ ΡΠ΅ΠΌΠΎΠ½ΡΠ΅ ΡΠΊΠ²Π°ΠΆΠΈΠ½ Π² Π’ΠΎΠΌΡΠΊΠΎΠΉ ΠΎΠ±Π»Π°ΡΡΠΈ Π½Π° ΠΏΡΠΈΠΌΠ΅ΡΠ΅ "ΠΡΡΠΎΠ²ΠΎΠΉ ΡΠ΅ΡΠ²ΠΈΡΠ½ΠΎΠΉ ΠΊΠΎΠΌΠΏΠ°Π½ΠΈΠΈ "ΠΠ ΠΠΠ"
ΠΠΏΡΠΈΠΌΠΈΠ·Π°ΡΠΈΡ ΡΠΈΡΡΠ΅ΠΌΡ ΡΠ»Π΅ΠΊΡΡΠΎΠΏΠΈΡΠ°Π½ΠΈΡ ΠΌΠ°Π³Π½ΠΈΡΠΎΠΏΠ»Π°Π·ΠΌΠ΅Π½Π½ΠΎΠ³ΠΎ ΡΡΠΊΠΎΡΠΈΡΠ΅Π»Ρ
Π ΠΠ€ΠΠ ΠΠ’
ΠΡΠΏΡΡΠΊΠ½Π°Ρ ΠΊΠ²Π°Π»ΠΈΡΠΈΠΊΠ°ΡΠΈΠΎΠ½Π½Π°Ρ ΡΠ°Π±ΠΎΡΠ° 143 Ρ., 52 ΡΠΈΡ., 16 ΡΠ°Π±Π»., 59 ΠΈΡΡΠΎΡΠ½ΠΈΠΊΠΎΠ², 6 ΠΏΡΠΈΠ».
ΠΠ»ΡΡΠ΅Π²ΡΠ΅ ΡΠ»ΠΎΠ²Π°: ΠΊΠΎΠ°ΠΊΡΠΈΠ°Π»ΡΠ½ΡΠΉ ΠΌΠ°Π³Π½ΠΈΡΠΎΠΏΠ»Π°Π·ΠΌΠ΅Π½Π½ΡΠΉ ΡΡΠΊΠΎΡΠΈΡΠ΅Π»Ρ, ΠΏΠΎΠ»ΡΡΠ΅Π½ΠΈΠ΅ ΠΌΠ΅Π΄Π½ΠΎΠ³ΠΎ ΠΏΠΎΠΊΡΡΡΠΈΡ, Π°Π»ΡΠΌΠΈΠ½ΠΈΠ΅Π²ΡΠ΅ ΠΊΠΎΠ½ΡΠ°ΠΊΡΠ½ΡΠ΅ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠΈ, Π΄Π²ΡΡ
ΠΈΠΌΠΏΡΠ»ΡΡΠ½ΡΠΉ ΡΠ΅ΠΆΠΈΠΌ ΡΠ°Π±ΠΎΡΡ, ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΡ ΠΈΠ·ΠΌΠ΅Π½Π΅Π½ΠΈΡ Π΄Π²ΠΈΠΆΠ΅Π½ΠΈΡ ΠΏΠ»Π°Π·ΠΌΡ
ΠΠ±ΡΠ΅ΠΊΡΠΎΠΌ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΡΠ²Π»ΡΠ΅ΡΡΡ (ΡΡΡΡ) ΡΠΈΡΡΠ΅ΠΌΠ° Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ ΠΊΠΎΠ°ΠΊΡΠΈΠ°Π»ΡΠ½ΠΎΠ³ΠΎ ΠΌΠ°Π³Π½ΠΈΡΠΎΠΏΠ»Π°Π·ΠΌΠ΅Π½Π½ΠΎΠ³ΠΎ ΡΡΠΊΠΎΡΠΈΡΠ΅Π»Ρ, Π½Π° ΠΏΡΠΈΠΌΠ΅ΡΠ΅ ΠΏΠΎΠ»ΡΡΠ΅Π½ΠΈΡ ΠΌΠ΅Π΄Π½ΠΎΠ³ΠΎ ΠΏΠΎΠΊΡΡΡΠΈΡ Π½Π° Π°Π»ΡΠΌΠΈΠ½ΠΈΠ΅Π²ΡΡ
ΠΊΠΎΠ½ΡΠ°ΠΊΡΠ½ΡΡ
ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΡΡ
Π¦Π΅Π»Ρ ΡΠ°Π±ΠΎΡΡ β ΠΎΠΏΡΠΈΠΌΠΈΠ·Π°ΡΠΈΠΈ ΡΠΈΡΡΠ΅ΠΌΡ ΡΠ»Π΅ΠΊΡΡΠΎΠΏΠΈΡΠ°Π½ΠΈΡ ΠΌΠ°Π³Π½ΠΈΡΠΎΠΏΠ»Π°Π·ΠΌΠ΅Π½Π½ΠΎΠ³ΠΎ ΡΡΠΊΠΎΡΠΈΡΠ΅Π»Ρ Π² Π΄Π²ΡΡ
ΠΈΠΌΠΏΡΠ»ΡΡΠ½ΠΎΠΌ ΡΠ΅ΠΆΠΈΠΌΠ΅ ΡΠ°Π±ΠΎΡΡ
Π ΠΏΡΠΎΡΠ΅ΡΡΠ΅ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΠΏΡΠΎΠ²ΠΎΠ΄ΠΈΠ»ΠΈΡΡ ΠΎΠΏΡΡΡ ΠΏΠΎ ΠΏΠΎΠ»ΡΡΠ΅Π½ΠΈΡ ΠΊΠΎΠ½ΡΠ°ΠΊΡΠ½ΡΡ
ΠΏΠ°Ρ ΠΌΠ΅Π΄Ρ-Π°Π»ΡΠΌΠΈΠ½ΠΈΠΉ, Π°Π½Π°Π»ΠΈΠ· ΠΈ ΠΎΠ±ΡΠ°Π±ΠΎΡΠΊΠ° ΠΏΠΎΠ»ΡΡΠ΅Π½Π½ΡΡ
Π΄Π°Π½Π½ΡΡ
Π ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΠ΅ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ Π±ΡΠ»ΠΈ ΠΏΠΎΠ»ΡΡΠ΅Π½Ρ ΠΊΠΎΠ½ΡΠ°ΠΊΡΠ½ΡΠ΅ ΠΏΠ°ΡΡ ΠΌΠ΅Π΄Ρ-Π°Π»ΡΠΌΠΈΠ½ΠΈΠΉ, ΠΏΡΠΎΠΈΠ·Π²Π΅Π΄Π΅Π½ Π°Π½Π°Π»ΠΈΠ· ΠΌΠ΅Π΄Π½ΠΎΠ³ABSTRACT
Final qualifying work consists of 143 p., 52 fig., 16 tab., 59 sources, 6 adj.
Keywords: coaxial magneto-plasma accelerator, copper coating, aluminum contact surfaces, a two-pulse operation mode, parameters change of the plasma motion.
The object of the research is the system based on coaxial magneto-plasma accelerator (CMPA) for preparation copper coating on aluminum contact surfaces.
The purpose of work - optimization of magneto-plasma accelerator power system in the two pulsed mode
During the research experiments were performed to obtain the contact pairs of copper-aluminum, analysis and processing of data
A result of research contact pair copper-aluminum were obtained, analyzes the copper coating on the contact surface of the aluminum, power system magneto-plasma accelerator
Magnetic Resonance Thermometry at 7T for Real-Time Monitoring and Correction of Ultrasound Induced Mild Hyperthermia
While Magnetic Resonance Thermometry (MRT) has been extensively utilized for non-invasive temperature measurement, there is limited data on the use of high field (β₯7T) scanners for this purpose. MR-guided Focused Ultrasound (MRgFUS) is a promising non-invasive method for localized hyperthermia and drug delivery. MRT based on the temperature sensitivity of the proton resonance frequency (PRF) has been implemented in both a tissue phantom and in vivo in a mouse Met-1 tumor model, using partial parallel imaging (PPI) to speed acquisition. An MRgFUS system capable of delivering a controlled 3D acoustic dose during real time MRT with proportional, integral, and derivative (PID) feedback control was developed and validated. Real-time MRT was validated in a tofu phantom with fluoroptic temperature measurements, and acoustic heating simulations were in good agreement with MR temperature maps. In an in vivo Met-1 mouse tumor, the real-time PID feedback control is capable of maintaining the desired temperature with high accuracy. We found that real time MR control of hyperthermia is feasible at high field, and k-space based PPI techniques may be implemented for increasing temporal resolution while maintaining temperature accuracy on the order of 1Β°C
A multi-center inter-manufacturer study of the temporal stability of phase-contrast velocity mapping background offset errors
Time-resolved angiography with stochastic trajectories for dynamic contrast-enhanced MRI in head and neck cancer: Are pharmacokinetic parameters affected?
Purpose To investigate the effects of different time-resolved angiography with stochastic trajectories (TWIST) k-space undersampling schemes on calculated pharmacokinetic dynamic contrast-enhanced (DCE) vascular parameters.Methods A digital perfusion phantom was employed to simulate effects of TWIST on characteristics of signal changes in DCE. Furthermore, DCE-MRI was acquired without undersampling in a group of patients with head and neck squamous cell carcinoma and used to simulate a range of TWIST schemes. Errors were calculated as differences between reference and TWIST-simulated DCE parameters. Parametrical error maps were used to display the averaged results from all tumors.Results For a relatively wide range of undersampling schemes, errors in pharmacokinetic parameters due to TWIST were under 10% for the volume transfer constant, Ktrans, and total extracellular extravascular space volume, Ve. TWIST induced errors in the total blood plasma volume, Vp, were the largest observed, and these were inversely dependent on the area of the fully sampled k-space. The magnitudes of errors were not correlated with Ktrans, Vp and weakly correlated with Ve.Conclusions The authors demonstrated methods to validate and optimize k-space view-sharing techniques for pharmacokinetic DCE studies using a range of clinically relevant spatial and temporal patient derived data. The authors found a range of undersampling patterns for which the TWIST sequence can be reliably used in pharmacokinetic DCE-MRI. The parameter maps created in the study can help to make a decision between temporal and spatial resolution demands and the quality of enhancement curve characterization
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