Maximum Intensity Change Research Articles

Sensitive Oligonucleotide Detection Using Resonant Coupling between Fano Resonance and Image Dipoles of Gold Nanoparticles.

The surface plasmon resonance (SPR)-based sensor has been widely used for biodetection. One of the attractive roles is the gold nanostructure with Fano resonance. Its sharp resonant profile takes advantage of the high figure of merit (FoM) in high-sensitivity detection. However, it is still difficult to detect small molecules at low concentrations due to the extremely low refractive index changes on the metallic surface. We propose using the coupling of image dipoles of gold nanoparticles (AuNPs) and Fano resonance of periodic capped gold nanoslits (CGNs) for sensitive small-molecule detections. The coupling mechanism was verified by three-dimensional finite-difference time-domain calculations and experiments. AuNPs on CGN form image dimer assemblies and induce image dipole with resonance wavelengths ranging from 730 to 550 nm. The surface plasmon polaritons (SPPs) interact with the image dipole of the AuNP on the CGNs and then scatter out through the periodic gold caps. The experimental results show that the peak intensity of grating resonance is decreased by the effect of image dipole and exhibits the maximum intensity change when the Fano resonance matches the resonance of image dipole. The 50 nm AuNPs can be detected with a surface density of less than one particle/μm2 by using the intensity change as the signal. With the resonant coupling between Fano resonance and image dipole extinction, the oligonucleotide with a molecular weight of 5.5 kDa can be detected at a concentration of 100 fM. The resonant coupling dramatically pushes the sensitivity boundary, and we report the limit of detection (LOD) to be 3 orders of magnitude lower than that of the prism-based SPR. This study provides a promising and efficient method for detecting low concentrations of small molecules such as aptamers, miRNA, mRNA, and peptides.

Indocyanine Green Fluorescence Imaging in Predicting Wound Healing After Limb Revascularization

Introduction - The most severe form of peripheral arterial disease is chronic limb threatening ischemia with tissue lesion. Assessment of critically ischemic foot is challenging.The conventional assessment methods are pressure measurements from ankle and toe level, ankle-brachial index (ABI) and transcutaneous oxygen pressure (TcPO2). Indocyanine green fluorescence imaging (ICG-FI) a relatively recent imaging method and still developing in many ways. The principle of ICG-FI is to illuminate the tissue of interest with light at the excitation wavelength (about 750 to 800nm) while observing it at longer emission wavelengths (over 800nm). ICG-FI gives a view of foot hemodynamic. After an intravenous injection of ICG, perfusion of the foot can be visualized with infrared camera and recorded for further analysis. Intensity of the fluorescence as a function of time can be analysed from the recorded images allowing a time-intensity curve to be drawn. We have earlier published analysis on the repeatability of ICG-FI and use of ICG-FI in immediate quality control after revascularization. In the current study we have analysed the use of ICG-FI in predicting wound healing after revascularization of CLTI and tissue lesion. Methods - Between January 2015 and February 2016 73 patients with CLTI and tissue lesion underwent either surgical (n=24) or endovascular (EVR) (n=49) revascularization. ICG-FI was done using Spy Elite before the revascularization, immediately after and during the follow-up. Maximum intensity, intensity rate and the relative change in the intensity rate were extracted from the automatic time intensity curve report. Results - During the mean follow-up of 16 months 77% of the wounds healed. 12 patients died and 9 had major amputation of the index leg. 4 mo, 6mo and overall wound healing rates were 51% and 63% respectively. The mean maximum intensity increased in the wound area from 92 (SD 61) AU to 132 (SD62) AU. The three parameters, change in maximum intensity, change in intensity rate and relative change in intensity rate were testes using ROC. The best area under curve was achieved with the absolute change in maximum intensity. 19AU increase predicted overall wound healing with 69% sensitivity and 68% specificity (AUC 0.79). 35 AU increase in intensity predicted wound healing in 4 months with 64% sensitivity and 63% specificity (AUC 0.68), 30 AU increase predicted wound healing in 6 months with 69% sensitivity and 69% specificity (AUC 0.72). In patients who underwent EVR the mean maximum intensity increased from 99.7 (SD 60.9) to 127.1 (SD 62.1) in the wound area. The corresponding increase in patients who underwent bypass was from 79.6 (SD60.1) AU to 140 (SD 62.9) AU (p<0.001). One-year wound healing rate after EVR was 84% and after bypass 92%. Conclusion - ICG-FI shows well the success of revascularization in individual patient. In our analysis the best parameter in predicting wound healing was absolute change in maximum intensity. The higher the change is achieved, the faster is the wound healing.

Characteristics of lightning activity in tropical cyclones developed over North Indian Ocean basin during 2010–2015

The characteristics of lightning activity in tropical cyclones (TCs) over North Indian Ocean (NIO) are presented using sample of 21 TCs developed during 2010–2015 using TRMM and World Wide Lightning Location Network (WWLLN) datasets along with information from annual reports of Regional Specialized Meteorological Center (RSMC), New Delhi. The microphysical features such as Polarization Corrected Brightness Temperature (PCT), attenuation corrected reflectivity factor, Ice Water Path (IWP) play a pivotal role in development of convective systems within TCs. The TCs exhibited systematic variation in lightning flashes per day within 300km of estimated center during their life cycle irrespective of their severity and flash rate within 300km of storm center. The lightning flashes ranged from 1 to 3500 flashes per day during pre-cyclone stage, 100 to 8000 flashes per day during cyclone stage and 0 to 4300 flashes per day during post-cyclone stage. The TCs produced maximum flash density in eyewall region (20–40km) and outer rainband region (200–260km). The WWLLN recorded 165,512 flashes within 300km of TC centers during their life cycle. The maximum flashes occurred during cyclone stage followed by pre-cyclone and post-cyclone. The time variation of flash rate for all cyclones was episodic and primarily peaked during late night and early morning hours. The diurnal variation of lightning flashes during TCs due to variation in detection efficiency of WWLLN also controls temporal distribution of lightning activity. During rapid intensification, TCs produced profuse lightning flashes per hour. Episodic lightning flashes per hour occurred during weakening stage and prior to landfall. It is evident that outbreaks of lightning flashes prior to maximum intensity change as manifested in maximum sustained wind speed and fall in estimated central pressure (ECP) indicate potential predictive value of lightning activity for TC intensity change.

Automatic analysis of constriction location in singleton and geminate consonant articulation using real-time magnetic resonance imaging

Research on geminate consonants has attempted to establish whether the control of their articulation differs from that of corresponding singletons in temporal parameters, spatial parameters, or both. One piece of evidence supporting spatial control in Italian geminates is EPG results revealing that the location of maximal constriction (CL) of coronal geminates along the palate exhibits small differences from the CL of singletons (Payne 2005). However, our recent work investigating Italian using real-time magnetic resonance imaging (MRI) has shown that when measuring CL dynamically, the CL of singletons and geminates are identical. Dynamic CL is defined as the region of the image that exhibits maximum intensity change during constriction formation and release. These results can be reconciled with the EPG findings if we hypothesize that differences in CL at the moment of maximal constriction are due to compression effects (in the longer geminates) involving the tongue tip sliding along the palate during the closure duration. We evaluate this hypothesis by testing whether CL differences between singletons and geminates can also be found in MRI data, when CL is measured statically (region on the palate contacted in the most constricted frame) in the same utterances in which dynamic CL is invariant. [Work supported by NIH.]

Complication of the spectrum of electromagnetic waves scattered by charged nanoparticles with allowance for radiation reaction

Peculiarities of the scattering of electromagnetic waves by charged nanoparticles have been revealed, given the proper expression for the radiation reaction force. These peculiarities (the change in maximum intensity, the appearance of additional peaks in the spectrum, and others) can be used, in particular, in near-Earth plasma physics and charged nanoparticle physics.

Paired-wavelength spectral approach to measuring the relative concentrations of two localized chromophores in turbid media: an experimental study

We present an experimental test of a new spectral approach that is aimed at quantifying the relative concentrations of two chromophores that are contained in a defect embedded in a turbid medium. The basic steps of our spectral approach are (a) perform a linear tandem scan of the source and detector across the defect; (b) measure the spectral dependence of the maximum change induced by the defect in the scanned intensity; (c) identify a set of appropriate pairs of wavelengths (lambda1, lambda2) at which such maximum intensity changes are the same; and (d) measure the reduced scattering coefficient spectrum of the background medium. For each wavelength pair (lambda1, lambda2), we obtain a measurement of the relative concentrations of the two chromophores, where the only required parameters are the extinction coefficients of the two chromophores and the ratio of the background scattering coefficients at lambda1 and lambda2. In a mixture of two test chromophores (blue food coloring dye and black India ink) contained in a 0.78-cm diameter cylinder, our spectral approach yielded relative concentrations values that were within 6% of their actual values. Although our paired-wavelength spectral approach is not generally applicable to any pair of chromophores, it is suitable for oxyhemoglobin and deoxyhemoglobin and is thus appropriate for oximetry of localized lesions in biological tissues.

Observational study of the seasonality of the submonthly and intraseasonal signal over the tropics

Atmospheric variability in outgoing long-wave radiation (OLR) and tropospheric relative vorticity (VOR) over the South American region was studied from 1979 to 1996 using the complex Morlet wavelet function. The analyses focus on spatial variation in intraseasonal and submonthly scales. Scalograms were used to measure submonthly intraseasonal oscillations in convection, which were found to be predominant in the tropical regions. However, 7-day and 15-day oscillations were observed at tropical and extratropical latitudes in spring and winter, indicating that transient disturbances play a more prominent role. Regarding VOR, tropical energy intensities were highest in the spring and summer, whereas subtropical and extratropical energy intensities were highest in the autumn and winter. The dynamics of the 25-day and 45-day VOR oscillations indicates a possible correlation with Rossby waves over the eastern tropical Pacific Ocean, mainly during the summer. During winter, the 7-day and 15-day VOR oscillations are more frequent at higher latitudes and are enhanced along storm tracks. It was also observed that convection amplitudes in the regions of maximum intensity change appreciably from year to year and from season to season, showing that the behavior of the submonthly and intraseasonal oscillations is nonperiodic and correlates strongly with El Nino/Southern Oscillation years. These results confirm the efficiency of wavelet analysis for time-scale studies of atmospheric variability.

Measurement of longitudinal piezoelectric coefficient of film with scanning-modulated interferometer

A scanning-modulated interferometer has been designed to measure the effective d 33 coefficient of piezoelectric film by monitoring the modality of surface vibration of an active electrode area together with its passive surroundings in response to the applied ac voltage. By introducing a slow modulation to an ordinary interferometer, accurate measurement of the maximum intensity change corresponding to the small vibration at the most sensitive quarter-wavelength point can be achieved by measuring the envelope amplitude of the modulated vibration signal. The environment disturbance can only affect the position at which the envelope peak occurs but cannot change its amplitude value. Therefore, very reliable measurement results can be achieved. The modulation technique enables the simultaneous measurement of the vibration signal V out and the reference signal V p–p, thus a real time calibration can be realized. Since the small displacement is proportional to the ratio of V out and V p–p, the testing result is neither susceptible to the roughness or reflectance change of the sample surface, nor to the instability of the laser intensity. Taking this advantage, it is possible to realize automatic scanning of the sample surface for measuring the vibration modality, while maintaining the measurement accuracy. The d 33 value of piezoelectric thick films made by composite coating processing was characterized by using this scanning-modulated interferometer. Typically, films with thicknesses ranging from 3 to 7 μm have effective d 33 value of more than 100 pm/V.

Optimization of off-null ellipsometry in sensor applications.

The optimization of azimuth angle settings of a polarizer-compensator-sample-analyzer off-null ellipsometric sensor system to obtain maximum intensity changes with respect to changes in the properties of a sensing layer, with and without considering changes in s reflectance, is studied. Optimal conditions in the two cases are derived analytically under the assumption that linear relationships exist among the changes in the parameters of the sensing layer. The validity of these optimal conditions is verified by numerical examples. The advantage of using ellipsometry compared with reflectometry to readout sensing information for some sensing samples is also discussed.

On the Canny edge detector

The Canny edge detector is widely used in computer vision to locate sharp intensity changes and to find object boundaries in an image. The Canny edge detector classifies a pixel as an edge if the gradient magnitude of the pixel is larger than those of pixels at both its sides in the direction of maximum intensity change. In this paper we will show that defining edges in this manner causes some obvious edges to be missed. We will also show how to revise the Canny edge detector to improve its detection accuracy.

Reactivation and refolding of rabbit muscle creatine kinase denatured in 2,2,2-trifluoroethanol solutions

The unfolding and refolding of creatine kinase (ATP:creatine N-phosphotransferase (CK), EC 2.7.3.2) during denaturation and reactivation by trifluoroethanol (TFE) have been studied. Significant aggregation was observed when CK was denatured at TFE concentrations between 10% and 40% (v/v). 50% TFE (v/v) was used to study the denaturation and unfolding of CK. The activity loss of CK was a very quick process, as was the marked conformational changes during denaturation followed by fluorescence emission spectra and far-ultraviolet CD spectra. DTNB modification and size exclusion chromatography were used to find that CK dissociated and was in its monomer state after denaturation with 50% TFE. Reactivation and refolding were observed after 80-fold dilution of the denatured CK into 0.05 M Tris-HCl buffer, pH 8.0. The denatured CK recovered about 38% activity following a two phase course (k1=4.82±0.41×10−3 s−1, k2=0.60±0.01×10−3 s−1). Intrinsic fluorescence maximum intensity changes showed that the refolding process also followed biphasic kinetics (k1=4.34±0.27×10−3 s−1, k2=0.76±0.02×10−3 s−1) after dilution into the proper solutions. The far-ultraviolet CD spectra ellipticity changes at 222 nm during the refolding process also showed a two phase course (k1=4.50±0.07×10−3 s−1, k2=1.13±0.05×10−3 s−1). Our results suggest that TFE can be used as a reversible denaturant like urea and GuHCl. The 50% TFE induced CK denaturation state, which was referred to as the ‘TFE state’, and the partially refolded CK are compared with the molten globule state. The aggregation caused by TFE during denaturation is also discussed in this paper.

Reactivation and refolding of reassociated dimers of rabbit muscle creatine kinase.

Creatine kinase (ATP:creatine N-phosphotransferase, EC 2.7.3.2) is a good model for studying dissociation and reassociation during unfolding and refolding. This study compares self-reassociated CK dimers and CK dimers that contain hybrid dimers under proper conditions. Creatine kinase forms a monomer when denatured in 6 M urea for 1 h which will very quickly form a dimer when the denaturant is diluted under suitable conditions. After modification by DTNB, CK was denatured in 6 M urea to form a modified CK monomer. Dimerization of this modified subunit of CK occurred upon dilution into a suitable buffer containing DTT. Therefore, three different types of reassociated CK dimers including a hybrid dimer can be made from two different CK monomers in the proper conditions. The CK monomers are from a urea-denatured monomer of DTNB-modified CK and from an unmodified urea dissociated monomer. Equal enzyme concentration ratios of these two monomers were mixed in the presence of urea, then diluted into the proper buffer to form the three types of reassociated CK dimers including the hybrid dimer. Reassociated CK dimers including all three different types recover about 75% activity following a two-phase course (k1 = 4.88 x 10(-3) s(-1), k2 = 0.68 x 10(-3) s(-1)). Intrinsic fluorescence spectra of the three different CK monomers which were dissociated in 6 M urea, dissociated in 6 M urea after DTNB modification, and a mixture of the first two dissociated enzymes were studied in the presence of the denaturant urea. The three monomers had different fluorescence intensities and emission maxima. The intrinsic fluorescence maximum intensity changes of the reassociated CK dimers were also studied. The refolding processes also follow biphasic kinetics (k1 = 3.28 x 10(-)3 s(-1), k2 = 0.11 x 10(-3) S(-1)) after dilution in the proper solutions. Tsou's method [Tsou (1988), Adv. Enzymol. Rel. Areas Mol. Biol. 61, 381-436] was also used to measure the kinetic reactivation rate constants for the different three types of reassociated CK dimers, with different kinetic reactivation rate constants observed for each type. CK dissociation and reassociation schemes are suggested based on the results.

The Effects of Climatological and Persistence Variables on the Intensities of Tropical Cyclones over the Eastern North Pacific Ocean

Abstract The effects of 10 climatological and persistence variables (latitude, maximum wind speed, 12-h change of maximum wind speed, longitude, distance to land, Julian date, sea surface temperature, speed of movement, zonal component of motion, and meridional component of motion) on changes of intensities of tropical cyclones over the eastern North Pacific Ocean were examined for the periods 1982–87 and 1988–93. Backward multiple regressions were performed to relate these 10 variables to changes in maximum intensity (as determined by wind speed) over periods ranging from 12 to 72 h. Latitude, maximum wind speed, and the 12-h change of maximum wind speed were the most significant variables. Each of the 10 variables was statistically significant at the 95% level at one or more of the time periods. Speed of movement, the component of motion, and the meridional component of motion were the least significant factors. The statistical relationships were tested using independent data from 1994. The mean absolut...

Differentiation of benign from malignant breast masses by time-intensity evaluation of contrast enhanced MRI

Using gadolinium-DTPA enhanced MRI we analyzed the enhancement characteristics of palpable breast masses in 23 patients—10 cancers and 13 benign lesions. The most specific finding for separating benign from malignant lesions was a ratio of maximum intensity change divided by the time interval during which this first occurred. Designated ranges of this ratio were specific for benign disease and sensitive for malignancy in this small patient group. Three of eight fibroadenomas exhibited enhancement patterns indistinguishable from cancer.

Time-resolved X-ray diffraction studies of frog skeletal muscle isometrically twitched by two successive stimuli using synchrotron radiation.

In order to clarify the delay between muscular structural changes and mechanical responses, the intensity changes of the equatorial and myosin layer-line reflections were studied by a time-resolved X-ray diffraction technique using synchrotron radiation. The muscle was stimulated at 12-13 degrees C by two successive stimuli at an interval (80-100 ms) during which the second twitch started while tension was still being exerted by the muscle. At the first twitch, the intensity changes of the 1.0 and 1.1 equatorial reflections reached 65 and 200% of the resting values, and further changes to 55 and 220% were seen at the second twitch, respectively. Although the second twitch decreased not only the time to peak tension but also that to the maximum intensity changes of the equatorial reflections (in both cases, about 15 ms), the delay (about 20 ms) between the intensity changes and the development of tension at the first twitch were still observed at the second twitch. On the other hand, the intensities of the 42.9 nm off-meridional and the 21.5 nm meridional myosin reflections decreased at the first twitch to the levels found when a muscle was isometrically tetanized, and no further decrease in their intensities was observed at the second twitch. These results indicate that a certain period of time is necessary for myosin heads to contribute to tension development after their arrival in the vicinity of the thin filaments during contraction.