Real IR Research Articles

Four-Hour-Delayed Gadolinium 3D REAL IR and SPACE FLAIR MRI Correlated to Meniere Disease Histology.

Objectives: This study aims to showcase the complementary nature of utilizing both histopathology and magnetic resonance imaging (MRI) in understanding the otologic pathophysiology of Meniere disease. In addition, it seeks to raise awareness of the value of preserving and curating historical temporal bone collections which continue to inform our understanding of otologic diseases. Methods: The essential anatomical feature of Meniere disease-the distended membranous labyrinth-is explored through a comparison of early temporal bone studies with contemporary MRI techniques. The histopathologic photomicrographs are of inner ear specimens from deceased patients with symptoms consistent with Meniere disease. The MRI sequences from living patients exhibiting classic Meniere disease symptoms during life are captured 4 hours post-administration of gadolinium. Results: Both histopathologic examination and MRI imaging reveal consistent distention of the saccule, utricle, and scala media in patients with Meniere disease. The study shows the histologic photomicrographs of actual Meniere patients compared to the MRIs and successfully demonstrates the correlation between postmortem histological findings and MRI evidence of distension in living patients. Conclusions: A corresponding distension of the membranous labyrinth is seen in both the histologic specimens and the Meniere MRIs. This correlation suggests the potential utility of utilizing MRI to aid in diagnosing atypical Meniere disease and distinguishing it from other disease processes, such as migraine equivalent vertigo. The integration of historical temporal bone studies with modern MRI techniques offers valuable insights into the pathophysiology of otologic diseases. In addition, it emphasizes the importance of preserving and curating historical temporal bone collections for continued research and medical education purposes. Previous studies of delayed MRIs did not use Meniere disease temporal bone histopathology images.

Robust infrared small target detection with multi-feature fusion

The performance of the infrared search and track system depends on the robust of the infrared small target detection. In this paper, a novel small target detection with multi-feature fusion is proposed. At first, the salient proposal region is obtained with phase spectrum Fourier transform (PFT). Then, geometric moment is utilized to design an adaptive steerable edges awareness factor, which effectively eliminates the strong edge clutters. Afterwards, we adopt a three-layers local contrast structure and the difference-ration form is introduced to enhance the target and suppress the complex backgrounds. Finally, the adaptive threshold is applied to extract the target in the saliency map. Experiments are conducted on four real IR image sequences, which demonstrate that the proposed method outperforms the comparing methods with various complex backgrounds.

Infrared small target detection using Homogeneity-weighted local patch saliency

Detecting infrared small targets (IRSTs) submerged in the complex back- grounds with heavy clutters is a challenging work of great significance in many fields. Inspired by representation capability of the superpixel, this paper presents a human visual system (HVS) based method called Homogeneity weighted local patch saliency (HWLPS). Firstly, the image is transformed into a superpixel graph and a compound flux field of the thermal intensity and gradient. Next, IRST component saliency and superpixel homogeneity are quantified by the morphing gradient direction diversity (GDD) metric and the inter-patch homogeneity (IPH) successively. Finally, the local contrast aggregation fuses the morphing GDD and the foreground saliency of image patches according to the superpixel graph. Experiments on various real IR image datasets show that, the proposed algorithm outperforms the state-of-the-art methods with robustness and stability against intricate back- grounds.

Experimental and numerical research on the solar updraft at a tall building façade

This work presents experimental and numerical research on the solar updraft at a tall building façade, which is 55 m high. The measurements are carried out in windless and cloudless weather, so the warmed by the solar irradiation façade is almost the only factor causing the buoyancy-driven airflow. A set of anemometers are used to record the vertical component of the air velocity. The mean value of the airflow velocity reached up to 2 m/s. However, the instantaneous value varied up to 4 m/s. A numerical model for the solar updraft is built using an ANSYS Fluent, and the temperature boundary condition at the façade is set based on a real IR image taken during the measurements. The numerical results are consistent with the experimental data and the theoretical considerations – at the upper façade edge, the total thickness of the buoyant plume is determined to be about 5 m, and the average airflow velocity is around 0.7 m/s. The strongly turbulent nature of the solar updraft is also confirmed.

A Novel MR Imaging Sequence of 3D-ZOOMit Real Inversion-Recovery Imaging Improves Endolymphatic Hydrops Detection in Patients with Ménière Disease.

The detection rate of premortem MR imaging endolymphatic hydrops is lower than that of postmortem endolymphatic hydrops in Ménière disease, indicating that current MR imaging techniques may underestimate endolymphatic hydrops. Therefore, we prospectively investigated whether a novel high-resolution MR imaging technique, the 3D zoomed imaging technique with parallel transmission real inversion-recovery (3D-ZOOMit real IR), would improve the detection of endolymphatic hydrops compared with conventional 3D TSE inversion-recovery with real reconstruction. Fifty patients with definite unilateral Ménière disease were enrolled and underwent 3D-ZOOMit real IR and 3D TSE inversion-recovery with real reconstruction 6 hours after IV gadolinium injection. The endo- and perilymph spaces were scored separately. The contrast-to-noise ratio, SNR, and signal intensity ratio of the 2 sequences were respectively calculated and compared. The presence of endolymphatic hydrops was evaluated. The endolymphatic space in the cochlea and vestibule was better visualized with 3D-ZOOMit real IR than with conventional 3D TSE inversion-recovery with real reconstruction (P < .001). There were differences between the 2 sequences in the evaluation of no cochlear hydrops and cochlear hydrops (both, P < .017). All contrast-to-noise ratio, SNR, and signal intensity ratio values of 3D-ZOOMit real IR images were statistically higher than those of conventional 3D TSE inversion-recovery with real reconstruction (all, P < .001). The 3D-ZOOMit real IR sequences are superior to conventional 3D TSE inversion-recovery with real reconstruction sequences in visualizing the endolymphatic space, detecting endolymphatic hydrops, and discovering contrast permeability.

Loop corrections in Minkowski spacetime away from equilibrium. Part I. Late-time resummations

Loop corrections to unequal-time correlation functions in Minkowski spacetime exhibit secular growth due to a breakdown of time-dependent perturbation theory. This is analogous to secular growth in equal-time correlators on time-dependent backgrounds, except that in Minkowski the divergences must not signal a real IR issue. In this paper, we calculate the late-time limit of the two-point correlator for different massless self-interacting scalar quantum field theories on a Minkowski background. We first use a late-time version of the in-in path integral starting in the vacuum of the free theory; in this limit, the calculation, including UV renormalization, reduces to that in in-out. We find linear or logarithmic growth in time, depending on whether the interaction strength is dimension-one or dimensionless, respectively. We next develop the Weisskopf-Wigner resummation method, that proceeds by demanding unitarity within a truncated Hilbert space, to calculate the resummed correlator and find that it gives an exact exponentiation of the late-time perturbative result. The resummed (unequal-time) correlator thus decays with an exponential or polynomial time-dependence, which is suggestive of ‘universal’ behavior that depends on the dimensions of the interaction strength.

Loop corrections in Minkowski spacetime away from equilibrium. Part II. Finite-time results

Loop corrections to finite-time correlation functions in quantum field theories away from equilibrium can be calculated using the in-in path integral approach. In this paper, we calculate the unequal-time two-point correlator for different massless self-interacting scalar quantum field theories on a Minkowski background, starting the field evolution at an arbitrary initial time. We find the counterterms that need to be added to UV-renormalize the result, including usual in-out counterterms in the dynamics and additional initial state counterterms that are required to cancel all UV divergences. We find that the late-time limit of the renormalized correlation function exhibits a linear or logarithmic growth in time, depending on whether the interaction strength is dimension-one or dimensionless, respectively. The late-time correlations match those obtained in our companion paper and, as shown there, the divergences do not indicate a real IR issue, consistent with what one would expect in Minkowski.

Sextic tensor model in rank 3 at next-to-leading order

We compute the four-loop beta functions of short and long-range multi-scalar models with general sextic interactions and complex fields. We then specialize the beta functions to a U(N)3 symmetry and study the renormalization group at next-to-leading order in N and small ϵ. In the short-range case, ϵ is the deviation from the critical dimension while it is the deviation from the critical scaling of the free propagator in the long-range case. This allows us to find the 1/N corrections to the rank-3 sextic tensor model of [1]. In the short-range case, we still find a non-trivial real IR stable fixed point, with a diagonalizable stability matrix. All couplings, except for the so-called wheel coupling, have terms of order ϵ0 at leading and next-to-leading order, which makes this fixed point different from the other melonic fixed points found in quartic models. In the long-range case, the corrections to the fixed point are instead not perturbative in ϵ and hence unreliable; we thus find no precursor of the large-N fixed point.

3D Real IR MR Findings in Acoustic Neuromas: Altered Perilymph Metabolism.

This study aimed to investigate the perilymph metabolism by analyzing the 3D real IR MR findings in acoustic neuroma (AN) after intravenous administration of gadolinium (Gd). Eleven patients (6 men and 5 women) diagnosed with AN were included, and 3D real IR MRI was performed 4hours after intravenous Gd injection. The signal intensity and details of inner ear, tumor, and internal auditory canal (IAC) by MRI were analyzed. Four patients had tumors confined to the IAC, and 5 had tumors that extended to the cerebellopontine angle cistern. The signal intensity of the cochlea, vestibule, and IAC fundus was conspicuously enhanced in 3D real IR images than the control side. One patient had a tumor in the cochlea, in which the signal intensity of the semicircular canal and vestibule was increased. One patient had an intravestibular tumor in which the signal intensity of the semicircular canal was increased and the cochlea had endolymphatic hydrops in the affected ear. The synchronously increased signal intensity in the inner ear and IAC may indicate that IAC may serve as a channel for removal of the perilymph in the inner ear; the blockage by the tumor may have changed the hydrodynamics of the perilymph to cause a longer retention of Gd in the inner ear.

New experimental investigation of the circumferential temperature uniformity for a PTC absorber

In this work, an experimental investigation of non-uniform circumferential temperature distribution (CTD) of a PTC absorber is done. Indeed, to evaluate the absorber CTD, a new method is reported by using real IR thermography profiles. The effects of focal length, absorber diameter, and outer glass cover (OGC) on the CTD are investigated. Moreover, a data visualization and statistical analysis are carried out. The most uniform and profitable flux distribution is found for a diameter of 0.042 m and a focal distance of 0.19 m. For this configuration, the highest ηO obtained in the cases with and without OGC is of about 57.16% and 60.87%, respectively. We notice that the temperature gradients and peaks increase gradually with the distance; a maximum temperature gap (ΔTmax) of 72 °C is reached for the distance of 0.26 m. In the case of OGC, the ΔTmax is only of about 63.6 °C (i.e., a difference of 8.4 °C). Thus, in the case of non-OGC, the highest mean and median temperatures of about 73.15 °C and 70.20 °C, respectively, are reported for a distance of 0.19 m. However, for the OGC case, the highest temperature values of about 80.8 °C and 76.8 °C, respectively, are reported for a distance of 0.22 m. In addition, the highest CTD uniformity is reported for a distance of 0.19 m, where an increase in the uniformity of about 2% is observed for the OGC use.

Analysis of ir spectra of hetero-metallic oxo-centered three-core carboxylates based on iron (iii) with the involvement of quantum-chemical calculation

The article is devoted to the study of the problems of detailed interpretation of vibrational spectra of oxo-centred trinuclear heterometallic carboxylates based on iron (III) of the general formula [Fe3+2M2+O(CH2XCOO)6(H2O)3], where M=Mn, Co or Ni; X=H, Cl or Br, by applying quantum chemical calculation. One of the problems in assigning the detected absorption bands in the infrared spectra of these compounds in the region of stretching vibrations with the participation of a heterometallic M atom is the superposition of highly intense peaks from bending vibrations of groups of carbon, oxygen and hydrogen atoms. The most common, complex and expensive method of isotopic substitution does not allow identifying individual peaks due to oscillations with the participation of M. The high-speed technique for calculating spectra is trying to solve this problem with sufficient accuracy. The vibrational spectrum of the compounds under study was calculated using the Gaussian-09 software package by the hybrid density functional theory DFT/B3LYP using the 3–21G basis set. Heterometallic oxo-carboxylates were synthesized according to a previously developed procedure based on the interaction of calcium salt of a carboxylic acid with a mixture of ferric and ferrous metal chlorides taken in a 2:1 ratio in an aqueous solution. The IR spectra of the compounds were measured on an “FT-IR Spectrum 2 Perkin Elmer” spectrophotometer in the form of KBr-based tablets. It is shown that the calculated IR spectra for heterobimetallic oxo-centred carboxylates are in satisfactory agreement with the experimentally measured spectra. Calculations have shown that little noticeable differences in the spectra of compounds with different heterometal Min the region of stretching vibrations with its participation are due to the low value of the extinction of the absorption bands. The possibility of visualizing the vibrations of each group of atoms in the molecule made it possible to unambiguously interpret the detected absorption bands in the real IR spectra of compounds and establish that the studied heterobimetallic carboxylate complexes have the structure of a n3-oxo cluster.

Robust infrared spectral deconvolution for image segmentation with spatial information regularization

Spectral distortion often occurs in spectral data due to the influence of the point spread function of the infrared spectrometer. However, the infrared spectrum commonly exists the issues of random noises and band overlap. Resolution enhancement is usually the first step in the preprocessing procedure of material classification and segmentation. In this article, we have developed a resolution- enhancement algorithm with total variation (TV-norm) constraints for the degraded IR spectrum due to overlap and noises degradation. The point spread function is calculated according to infrared spectrometer system and Fourier-optical theory. Introducing the adaptive total variation, the constraint regularization, the proposed model can not only remove noises well but also estimate the point spread function simultaneously. This model is examined by a set of simulated IR spectrum with Poisson noises and a series of real IR spectra. Performance comparison with other state-of-the-art methods is made. The enhanced infrared spectrum can provide highly useful information for image segmentation.

Comprehensive comparison of MR image quality between intratympanic and intravenous gadolinium injection using 3D real IR sequences

Background: Intratympanic and intravenous gadolinium administration is used to visualise endolymphatic hydrops.Aims/objectives: The goal of this study was to compare the image quality between intratympanic (IT-method) and intravenous (IV-method) gadolinium administration using three-dimensional inversion recovery with real reconstruction (3D real IR) sequences.Materials and methods: A number of 152 patients with Meniere’s disease were included. The 3D real IR sequence was performed 24 h after IT administration or 4 h after IV administration. The detection rate of endolymphatic hydrops, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) of the two methods were compared. Specifically, the average image scores of the two methods were evaluated by two radiologists.Results: The SNRROI and CNRs of the IT-method were higher than those of the IV-method, whereas no significant difference between the IT-method and IV-method with regard to the SNRB was found. The average image scores were 3.49 ± 0.12 and 3.30 ± 0.12 for the IT-method and IV-method, respectively (p = .229). No statistically significant difference was found between two methods in terms of the detection rate of endolymphatic hydrops.Conclusions and significance: IT-method images can display endolymphatic hydrops more precisely than IV-method images. The IV-method can be used as an alternative to the IT-method in clinical applications to some extent.

Structure Simulation and Calculation of the Energy of Interaction of the Fragments of Cellulose Macromolecules

Quantum chemistry methods were used to calculate the energy parameters of an elementary unit and a cellulose macromolecule dimer (cellobiose), and structure simulation was performed and the energy of interaction between the fragments of native cellulose macromolecules was calculated. It was established that the trans conformation of cellobiose is more stable than the cis conformation by 6.7 kcal/mol. Differences in the calculated and real (according to literature data) IR spectra of cellulose were related to the presence of intramolecular and intermolecular hydrogen bonds in the native structure. It was shown that the interaction of individual fragments of cellulose macromolecules from eight monomer units is due to the manifestation of intramolecular hydrogen bonds. It was found that the energies of intermolecular interactions ∆Е essentially depend on the terminal groups X in the cellulose macromolecule fragments, and they are –26, 49, and ‒32 kcal/mol for X = –H, –COOH, and –COH, respectively. The structure of the interacting fragments of cellulose macromolecules can be regulated by replacing the hydrogen atoms of hydroxyl or terminal groups of the macromolecules with functional groups that do not form intramolecular hydrogen bonds and impede self-organization into fibrillar structures. It was shown that compounds with a high electron affinity or a negative energy of the lower vacant molecular orbital are the best reagents for complexation reactions with cellulose.

Assessment of Cochlea Endolymphatic Hydrops Using 3-D FLAIR and 3-D Real IR Sequence in Guinea Pigs via 3T MRI After Intratympanic Gadolinium: A Histopathological Comparison.

We assessed whether the three-dimensional fluid-attenuated inversion-recovery (3-D FLAIR) and three-dimensional inversion-recovery with real reconstruction (3-D real IR) sequences can be used to detect cochlea endolymphatic hydrops (EHs) in guinea pigs using 3 Tesla magnetic resonance imaging (3T MRI). The results of 3-D real IR imaging were compared with histopathological outcomes. Fourteen healthy men and women albino guinea pigs were used in this study. Their right ears received procedures that promoted EHs, and their left ears were used as untreated controls. High-resolution 3T MRI, combined with the intratympanic injection of gadolinium (Gd) in both ears, was performed 8 to 12 weeks after surgery. Both sides of the cochlea midmodiolar sections were observed under a light microscope and saved as the histopathological images. The signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) between the T2-weighted 3-D FLAIR and T2-weighted 3-D real IR sequences were compared. The appearance of EHs in the basal, second, third, and apical turns of the cochlea was further evaluated using 3-D FLAIR, 3-D real IR, and the histopathological images. Moreover, the maximum scala media area ratios (SMRs) on the histopathological sections were compared with the grading of the EHs on the 3-D real IR sequence with regard to each turn of the cochlea. Significant differences were found between the 3-D FLAIR and 3-D-real IR sequences with regard to the SNRs and CNRs (p < 0.05): the 3-D FLAIR sequence exhibited higher SNRs (SNRROI: 347.95 ± 105.01; SNRB: 103.28 ± 17.61) compared with the 3-D real IR sequence (SNRROI: 86.71 ± 30.11; SNRB: 11.11 ± 3.45), whereas the 3-D real IR sequence showed higher CNRs (2.78 ± 0.58) compared with the 3-D FLAIR sequence (2.18 ± 0.55). Various degrees of EHs were observed in each turn of the cochlea in the experimental ears on the basis of the histopathological images. Thirteen, 10, 4, and 0 EHs were observed in the basal, second, third, and apical turns of the cochlear using 3-D FLAIR images, respectively, whereas 14, 14, 14, and 13 EHs were found using 3-D real IR images, respectively. Significant differences were found between the two sequences when evaluating the second, third, and apical turns of the cochlear but not with regard to the basal turn (p < 0.05). The SMRs were proportional to the extent of the EHs on 3-D real IR imaging in each turn of the cochlea. 3-D real IR images are clearer than 3-D FLAIR images, and they can display cochlea EHs more precisely using 3T MRI in guinea pigs. The extent of the EHs on 3-D real IR imaging was more consistent with the histopathological observations in each turn of the cochlea.

Directional support value of Gaussian transformation for infrared small target detection.

Robust small target detection is one of the key techniques in IR search and tracking systems for self-defense or attacks. In this paper we present a robust solution for small target detection in a single IR image. The key ideas of the proposed method are to use the directional support value of Gaussian transform (DSVoGT) to enhance the targets, and use the multiscale representation provided by DSVoGT to reduce the false alarm rate. The original image is decomposed into sub-bands in different orientations by convolving the image with the directional support value filters, which are deduced from the weighted mapped least-squares-support vector machines (LS-SVMs). Based on the sub-band images, a support value of Gaussian matrix is constructed, and the trace of this matrix is then defined as the target measure. The corresponding multiscale correlations of the target measures are computed for enhancing target signal while suppressing the background clutter. We demonstrate the advantages of the proposed method on real IR images and compare the results against those obtained from standard detection approaches, including the top-hat filter, max-mean filter, max-median filter, min-local-Laplacian of Gaussian (LoG) filter, as well as LS-SVM. The experimental results on various cluttered background images show that the proposed method outperforms other detectors.

Relative stabilities of HCl•H2SO4•HNO3 aggregates in polar stratospheric clouds.

Strong acids such as HCl (C), HNO3 (N) and H2SO4 (S) acquire relevance in Polar Stratospheric Clouds (PSCs) and aerosols in which nucleation processes occur. Ab initio quantum chemical studies of aggregates were performed for these strong acids. Structures were calculated using DFT methods with the B3LYP hybrid functional and aug-cc-pVTZ basis set. As an initial constraint, an H2SO4 moiety was placed in all candidate structures. A total of 11 optimized structures was found: a global minimum (CSN-a) plus ten local minima on the Potential Energy Surface (PES). The global minimum aggregate gave four hydrogen bonds, yielding a hexagonal ring in its structure. HNO3 acts as proton donor in all clusters; nevertheless, using trans-H2SO4 as the proton donor yielded the most stable structures, whereas HCl acts mainly as a proton donor/acceptor. Real harmonic frequencies, IR spectra, and inter-monomeric parameters were obtained. CSN-a symmetric stretching modes were shifted to 2805.56 cm(-1) and 3520.00 cm(-1) for H-Cl modes, while O-H modes shifted to 3256.87 cm(-1) and 3362.47 cm(-1). On the other hand, relative stabilities improved for 5 of the 11 aggregates when the temperature decreased from 298 K to 210 K, 195 K and 188 K. The aggregate CSN-f remained unstable only at 210 K. Moreover, the relative Gibbs free energy, ΔG(0-298K) was -9.26 kcalmol(-1) with respect to CSN-a; relative reaction Gibbs free energy [Δ(ΔG)] values ranged from 0.0 at 298 K, to -6.9 kcalmol(-1) at 188 K. It seems that CSN aggregates remain slightly more stable than CNS aggregates with a HNO3 moiety when the temperature decreases from 298 to 188 K. Five structures remained relatively stable under both study conditions.

Fast iterative adaptive nonuniformity correction with gradient minimization for infrared focal plane arrays

A fast scene-based nonuniformity correction algorithm is proposed for fixed-pattern noise removal in infrared focal plane array imagery. Based on minimization of L0 gradient of the estimated irradiance, the correction function is optimized through correction parameters estimation via iterative optimization strategy. When applied to different real IR data, the proposed method provides enhanced results with good visual effect, making a good balance between nonuniformity correction and details preservation. Comparing with other excellent approaches, this algorithm can accurately estimate the irradiance rapidly with fewer ghosting artifacts.

Millimeter imaging of submillimeter galaxies in the COSMOS field: redshift distribution

We present new IRAM PdBI 1.3mm continuum observations at ~1.5" resolution of 28 SMGs previously discovered with the 870um bolometer LABOCA at APEX within the central 0.7deg2 of the COSMOS field. 19 out of the 28 LABOCA sources were detected with the PdBI at a >~3sigma level of ~1.4mJy/b. A combined analysis of this new sample with existing interferometrically identified SMGs in the COSMOS field yields the following results: 1) >~15%, and possibly up to ~40% of single-dish detected SMGs consist of multiple sources, 2) statistical identifications of multi-wavelength counterparts to the single-dish SMGs yield that only ~50% of these single-dish SMGs have real radio or IR counterparts, 3) ~18% of interferometric SMGs have only radio or even no multi-wavelength counterpart at all, and 4) ~50-70% of z>~3 SMGs have no radio counterparts down to an rms of 7-12uJy at 1.4GHz. Using the exact interferometric positions to identify proper multi-wavelength counterparts allows us to determine accurate photometric redshifts for these sources. The redshift distributions of the combined and the individual 1.1mm and 870um selected samples have a higher mean and broader width than the redshift distributions derived in previous studies. Our sample supports the previous tentative trend that on average brighter and/or mm-selected SMGs are located at higher redshifts. There is a tentative offset between the mean redshift for the 1.1mm (<z>=3.1+/-0.4) and 870um (<z>=2.6+/-0.4) selected samples, with the 1.1mm sources lying on average at higher redshifts. Based on our nearly complete sample of AzTEC 1.1mm SMGs within a uniform 0.15deg2 area we infer a higher surface density of z>~4 SMGs than predicted by current cosmological models. In summary, our findings imply that (sub-)millimeter interferometric identifications are crucial to build statistically complete and unbiased samples of SMGs.

Efficient single image stripe nonuniformity correction method for infrared focal plane arrays

We present a novel, stripe nonuniformity correction algorithm for infrared focal plane arrays. This method relies on the separation of nonuniformity and true scene, and the nonuniformity correction parameter is obtained by traversing the error function of two adjacent columns’ pixels in local template window. Based on the succession of two adjacent columns’ correlation, the stripe nonuniformity correction can be achieved in a single frame. Experimental results, to illustrate the performance of the method, include the use of infrared image sequences with simulated nonuniformity and a diverse set of real IR imagery.