Anomalous Variation Research Articles

A Novel Magnetic Respiratory Sensor for Human Healthcare

Breathing is vital to life. Therefore, the real-time monitoring of a patient′s breathing pattern is crucial to respiratory rehabilitation therapies, such as magnetic resonance exams for respiratory-triggered imaging, chronic pulmonary disease treatment, and synchronized functional electrical stimulation. While numerous respiratory devices have been developed, they are often in direct contact with a patient, which can yield limited data. In this study, we developed a novel, non-invasive, and contactless magnetic sensing platform that can precisely monitor a patient′s breathing, movement, or sleep patterns, thus providing efficient monitoring at a clinic or home. A magneto-LC resonance (MLCR) sensor converts the magnetic oscillations generated by a patient′s breathing into an impedance spectrum, which allows for a deep analysis of one′s breath variation to identify respiratory-related diseases like COVID-19. Owing to its ultrahigh sensitivity, the MLCR sensor yields a distinct breathing pattern for each patient tested. It also provides an accurate measure of the strength of a patient′s breath at multiple stages as well as anomalous variations in respiratory rate and amplitude. The sensor can thus be applied to detect symptoms of COVID-19 in a patient, due to shortness of breath or difficulty breathing, as well as track the disease′s progress in real time.

Anomalous Temperature Dependence of Photoluminescence Caused by Non-Equilibrium Distributed Carriers in InGaN/(In)GaN Multiple Quantum Wells.

An increase of integrated photoluminescence (PL) intensity has been observed in a GaN-based multiple quantum wells (MQWs) sample. The integrated intensity of TDPL spectra forms an anomalous variation: it decreases from 30 to 100 K, then increases abnormally from 100 to 140 K and decreases again when temperature is beyond 140 K. The increased intensity is attributed to the electrons and holes whose distribution are spatial non-equilibrium distributed participated in the radiative recombination process and the quantum barrier layers are demonstrated to be the source of non-equilibrium distributed carriers. The temperature dependence of this kind of spatial non-equilibrium carriers’ dynamics is very different from that of equilibrium carriers, resulting in the increased emission efficiency which only occurs from 100 to 140 K. Moreover, the luminescence efficiency of MQWs with non-equilibrium carriers is much higher than that without non-equilibrium carriers, indicating the high luminescence efficiency of GaN-based LEDs may be caused by the non-equilibrium distributed carriers. Furthermore, a comparison analysis of MQWs sample with and without hydrogen treatment further demonstrates that the better quantum well is one of the key factors of this anomalous phenomenon.

Review of model-based and data-driven approaches for leak detection and location in water distribution systems

Abstract Leak detection and location in water distribution systems (WDSs) is of utmost importance for reducing water loss, which is, however, a major challenge for water utility companies. To this end, researchers have proposed a multitude of methods to detect such leaks in WDSs. Model-based and data-driven approaches, in particular, have found widespread uses in this area. In this paper, we reviewed both these approaches and classified the techniques used by them according to their leak detection methods. It is seen that model-based approaches require highly calibrated hydraulic models, and their accuracies are sensitive to modeling and measurement uncertainties. On the contrary, data-driven approaches do not require an in-depth understanding of the WDS. However, they tend to result in high false positive rates. Furthermore, neither of these approaches can handle anomalous variations caused by unexpected water demands.

The ionospheric condition and GPS positioning performance during the 2013 tropical cyclone Usagi event in the Hong Kong region

The ionosphere plays a critical role in the electromagnetic waves in communication systems such as the global positioning system (GPS). However, it is suspected that the strong convection during the tropical cyclone (TC) events can be a trigger to anomalous electron density variation in the ionosphere. This study analyzed the variation of three ionosphere-related parameters based on the GPS data including scintillation index S4, cycle slips, and total electron content (TEC) rate (TECR) during the tropical cyclone event (the 2013 TC Usagi) in the Hong Kong region. The results showed that the ionosphere-related parameters had a consistent significant increase on the second day after the Usagi made landfall near Hong Kong. Consequently, the positioning performance of GPS precise point positioning (PPP) and relative positioning modes was degraded. The degradation was ~ 138%, ~ 181%, and ~ 460% in the east (root mean square (RMS) 0.050 m), north (RMS 0.045 m), and up (RMS 0.185 m), respectively, compared with the RMS of 0.021 m in the east, 0.016 m in the north, and 0.033 m in the up on the normal day. Regarding the relative positioning, the positioning errors in the east (RMS 0.134 m) and north (RMS 0.118 m) directions were ~ 7.1 and ~ 7.9 times, respectively, as large as the RMS of 0.019 m in the east and 0.015 m in the north on the normal day. The positioning errors in the up (RMS 0.513 m) direction were ~ 12.2 times larger than the RMS of 0.042 m on the normal day.

Spin–phonon interaction and magnetoelastic coupling associated with unusual cluster-glass states in YFe0.9Cr0.1O3

The magnetic, optical phonon behavior of the polycrystalline YFe0.9Cr0.1O3 (YFC-10), prepared by solid-state reaction route, had been studied via static and ac magnetization measurements and Raman spectroscopic techniques respectively. The results indicated that YFe0.9Cr0.1O3 undergoes unusual cluster-glass transitions at low temperatures viz. Tf1 (SG1) = 108 K (Freez.1) and Tf2 (SG2) = 30 K (Freez.2) coexisting with the long-range weak ferromagnetic (WFM) state. Raman spectroscopic (RS) measurements revealed 12 distinct modes of vibrations at all temperatures with 83–433 K. Interestingly, the freezing transition at Tf1 is found to be accompanied by significant phonon renormalization. From the detailed analysis of the line-shape function of the Raman modes, the anomalous T-variation of the peak position and the linewidths suggests the existence of spin-phonon interaction in the present solid solution. Moreover the temperature dependent synchrotron X-ray diffraction studies between 10 and 300 K revealed the anomalous thermal variation of the lattice parameters and microscopic structural parameters such as super-exchange angles and (Fe/Cr)O6 octahedral bond lengths and bond angles at both the freezing transitions. Overall, the system exhibits the strong magnetoelastic and spin phonon coupling over a broad thermal regime viz. from Liquid. N2 to temperatures above room temperature (RT = 300 K) which makes YFe0.9Cr0.1O3 reliable for application purpose.

Spin-induced negative thermal expansion and spin\u2013phonon coupling in van der Waals material CrBr3

The two-dimensional van der Waals (vdW) magnets retaining magnetic order in atomically thin limit demonstrate challenging physical phenomena and they are considered as prospective building blocks for construction of advanced spintronics and nanoelectronics devices. Here, we present experimental evidence for negative thermal expansion of lattice volume and vdW layers and strong spin–phonon coupling effects, caused by formation of the long-range ferromagnetic order in the vdW material CrBr3. The neutron and X-ray diffraction measurements revealed anomalous temperature variation of lattice parameters and interatomic distances and angles in the vicinity of Curie temperature (TC). A pronounced rise of the frequencies of the most of the observed vibrational modes and unusual reversal broadening of their full widths at half maximum below TC was found from Raman spectroscopy measurements.

The Effect of Al2O3 Oxygen Sub-Lattice on Femon2 Phase Stability

All Magnetic phase transition in Iron Molybdate Nitride (FeMoN2) has been studied within the framework of density-functional theory, using generalized gradient approximation (GGA) as exchange correlation functionals. In this study, we suppose that, under the application of pressure, a uni-axial out-of plane structure optimization were done, where the in plane lattice parameters are fixed, within the pressure range of -50Kbar to 600Kbar. We found that the compound save the same structure (P6 3 /mmc) with a volume collapses. The volume and magnetic moment of FeMoN2 in its spin polarized case as well as none spin polarized case, have also been computed as ground state properties. The Magnetic moment of the FeMoN2 undergoes an anomalous variation accompanied by volume collapse. This volume collapse is attributed to a large variation in the out-of-plane lattice parameter.

TNNG: Total Nuclear Norms of Gradients for Hyperspectral Image Prior

We introduce a novel regularization function for hyperspectral image (HSI), which is based on the nuclear norms of gradient images. Unlike conventional low-rank priors, we achieve a gradient-based low-rank approximation by minimizing the sum of nuclear norms associated with rotated planes in the gradient of a HSI. Our method explicitly and simultaneously exploits the correlation in the spectral domain as well as the spatial domain. Our method exploits the low-rankness of a global region to enhance the dimensionality reduction by the prior. Since our method considers the low-rankness in the gradient domain, it more sensitively detects anomalous variations. Our method achieves high-fidelity image recovery using a single regularization function without the explicit use of any sparsity-inducing priors such as ℓ0, ℓ1 and total variation (TV) norms. We also apply this regularization to a gradient-based robust principal component analysis and show its superiority in HSI decomposition. To demonstrate, the proposed regularization is validated on a variety of HSI reconstruction/decomposition problems with performance comparisons to state-of-the-art methods its superior performance.

Spalling Characteristics Associated with Shock-Induced Microstructure Based on Molecular Dynamics Simulation of Single-Crystal Aluminum

This Letter reports an anomalous discontinuous variation in spall strength associated with shock-induced microstructure. It is known that elastic deformation, dislocation and stacking fault, and shock FCC-BCC phase transition will appear in turn with the increase of shock intensity. Our molecular dynamics simulations of single-crystal aluminum reveal that the damage evolution during release process may show an evident dependence on the shock-induced microstructure. The nanovoids nucleate homogeneously in the region of elastic deformation or phase transition, resulting in higher spall strength. However, the nanovoids nucleate heterogeneously in the region of dislocation and stacking fault, which leads to a sudden decrease in spall strength. This anomalous change is accompanied by a higher temperature rise, and we find that both homogeneous and heterogeneous nucleation satisfy the same spall strength-spall temperature relationship.

Anomalous Celiac Trunk Variation Encountered in Y-90 Radioembolization

Background: 
 Yttrium-90 microsphere embolization is a selective internal radiation therapy (SIRT) used in the treatment of hepatocellular carcinoma and liver metastases. Current literature recommends lobar, or more selective, infusion of SIRT to allow for precise radiation administration and to mitigate risk of non-target embolization. Lobar infusion requires knowledge of anatomical variations of hepatic arterial supply. The trifurcation of the celiac trunk into the left gastric artery, splenic artery, and common hepatic artery is the most common presentation representing 51% to 89% of patient anatomy. A replaced right hepatic artery (RHA) arising from the superior mesenteric artery (SMA) is one of the most common variants of hepatic arterial supply with a prevalence of 10.6% to 15%. Common variations such as these are well described and easily mapped using catheter angiography, but rarer variations are not as well described and more challenging to map. 
 
 Project Methods: 
 Mapping catheter angiogram of the celiac trunk and SMA was obtained. Additional aortogram and CT angiogram were obtained to further elucidate patient’s anatomy. 
 
 Results: 
 Initial mapping angiogram was only partially successful because the RHA could not be selected. Abdominal aortogram and CT angiogram of the abdomen and pelvis revealed a replaced RHA arising directly from the distal celiac trunk. Additionally, the patient had a replaced cystic artery arising from the left hepatic artery and an arc of Buhler connecting the proximal SMA to the proximal aspect of the right hepatic artery. 
 
 Conclusion: 
 Radiologists need to be aware of rare variations in hepatic arterial supply for the safe and effective treatment of hepatic neoplasms, whether primary or metastatic. Description of arterial variation and informed selection of arterial branches will remain a critical aspect of improving efficiency and reducing risks of hepatic embolization procedures.

Anomalous azimuthal variations with 360° periodicity of Rayleigh phase velocities observed in Scandinavia

SUMMARY We use the recently deployed ScanArray network of broad-band stations covering most of Norway and Sweden as well as parts of Finland to analyse the propagation of Rayleigh waves in Scandinavia. Applying an array beamforming technique to teleseismic records from ScanArray and permanent stations in the study region, in total 159 stations with a typical station distance of about 70 km, we obtain phase velocities for three subregions, which collectively cover most of Scandinavia (excluding southern Norway). The average phase dispersion curves are similar for all three subregions. They resemble the dispersion previously observed for the South Baltic craton and are about 1 per cent slower than the North Baltic shield phase velocities for periods between 40 and 80 s. However, a remarkable sin(1θ) phase velocity variation with azimuth is observed for periods >35 s with a 5 per cent deviation between the maximum and minimum velocities, more than the overall lateral variation in average velocity. Such a variation, which is incompatible with seismic anisotropy, occurs in northern Scandinavia and southern Norway/Sweden but not in the central study area. The maximum and minimum velocities were measured for backazimuths of 120° and 300°, respectively. These directions are perpendicular to a step in the lithosphere–asthenosphere boundary (LAB) inferred by previous studies in southern Norway/Sweden, suggesting a relation to large lithospheric heterogeneity. In order to test this hypothesis, we carried out 2-D full-waveform modeling of Rayleigh wave propagation in synthetic models which incorporate a steep gradient in the LAB in combination with a pronounced reduction in the shear velocity below the LAB. This setup reproduces the observations qualitatively, and results in higher phase velocities for propagation in the direction of shallowing LAB, and lower ones for propagation in the direction of deepening LAB, probably due to the interference of forward scattered and reflected surface wave energy with the fundamental mode. Therefore, the reduction in lithospheric thickness towards southern Norway in the south, and towards the Atlantic ocean in the north provide a plausible explanation for the observed azimuthal variations.

Toward the development of a multi parametric system for a short-term assessment of the seismic hazard in Italy

With the aim to develop a multi-parametric system devote to improving our present capability to assess seismic hazard particularly in the short-medium term, the preliminary step is to identify those parameters that have demonstrated their non-casual relation with earthquake occurrences and whose anomalous variations can be associated to the complex seismic process. Since 80, fluctuations of Earth thermally emitted radiation, measured by satellite sensors in the Thermal InfraRed (TIR) spectral region, have been reported by several authors in some connection with the occurrence of earthquakes; they and can be considered as one of the possible parameters to include within a multi-parametric system. In this paper, the Robust Satellite Techniques (RST) approach has been exploited to highlight Significant Sequences of TIR Anomalies (SSTAs) possibly related to seismic events happened in Italy in the period June 2004 - December 2014. In particular, we evaluated the level of correlation between occurrence of earthquakes with M≥4 and RST-based TIR anomalies using two different spatial resolutions of MSG-SEVIRI (Meteosat Second Generation -Spinning Enhanced Visible and Infrared Imager) images. Results of the two RST analyses show that the 82% of the identified SSTAs does not disappear when downscaled spatial resolution SEVIRI TIR records were used. For both analyses, more than 60% of SSTAs is apparently in connection with the occurrence of M≥4 earthquakes; more than the 80% of them has tendency to anticipate the occurrence of earthquakes. Although about the 40% of SSTAs is not apparently related to documented seismic activity (false positives), results of random tests (i.e. Molchan’s error diagrams) indicate a non-casual correlation between SSTAs and earthquake occurrences. These results confirm that the parameter “RST-based satellite TIR anomalies” is one of the possible candidates to be included in a multi-parametric system for time-Dependent Assessment of Seismic Hazard (t-DASH).

Pressure-Regulated Dynamic Stereochemical Role of Lone-Pair Electrons in Layered Bi2O2S.

Lone-pair electrons (LPEs) ns2 in subvalent 14 and 15 groups lead to highly anharmonic lattice and strong distortion polarization, which are responsible for the groups' outstanding thermoelectric and optoelectronic properties. However, their dynamic stereochemical role in structural and physical properties is still unclear. Here, by introducing pressure to tune the behavior of LPEs, we systematically investigate the lone-pair stereochemical role in a Bi2O2S. The gradually suppressed LPEs during compression show a nonlinear repulsive electrostatic force, resulting in two anisotropic structural transitions. An orthorhombic-to-tetragonal phase transition happens at 6.4 GPa, caused by the dynamic cation centering. This structural transformation effectively modulates the optoelectronic properties. Further compression beyond 13.2 GPa induces a 2D-to-3D structural transition due to the disappearance of the Bi-6s2 LPEs. Therefore, the pressure-induced LPE reconfiguration dominates these anomalous variations of lattice, electronic, and optical properties. Our findings provide new insights into the materials optimization by regulating the characters of LPEs.

Appearance of the Coast Effect in Tectonic Deformations Due to Magnetic Storms

The records from fifty-eight identical broadband seismic stations located in different regions of the world have been studied from the strong geomagnetic storm of October 29–31, 2003. Oscillations with a period of 12–24 h have been analyzed. The stations located at a distance of 100 km from the coast of the ocean demonstrated anomalous variations in the strain rate after the storm. The effect lasted for a few days, and its amplitude reached several millimeters per minute.

The effect of cold-start emissions on the diurnal variation of carbon monoxide concentration in a city centre

The diurnal variation of pollutants such as particles and carbon monoxide (CO) in urban environments typically follow the traffic density, with two peaks coinciding with the weekday morning and evening rush-hour periods. However, observations made in central Brisbane, the third largest city in Australia, demonstrated an anomalous diurnal variation with the CO peak in the evening being significantly higher than that in the morning. This imbalance was not observed for particle concentrations. Here, we show that the imbalance is a direct result of the difference in CO emission factors from motor vehicles during warm and cold starts. Over 30,000 cars with warmed-up engines enter Brisbane city centre car parks every weekday morning. They all start their engines from cold and leave the city in the evening, producing the anomalously higher emissions of CO in the city centre. This pattern of air quality, while clearly apparent within the city car parks and within the central business district of the city, was not observed outside the city limits and in the suburbs. To the best of our knowledge, no previous study has drawn attention to this phenomenon and no explanation has been provided in the literature to-date.

Steady-state temperature distribution under near-field radiative heat transfer inside a linear chain of polaritonic nanoparticles

Thermal transport mediated by near-field interactions is superdiffusive in an ordered network of nanoparticles, such as linear chains. Based on such nanostructures, here we study a classical thermal-nonequilibrium problem, that is, the steady-state temperature distribution inside the chain of equally spaced polaritonic nanoparticles. The existence of the linear temperature profile and anomalous temperature variations in the inner region and near the boundary of a dense chain embedded in vacuum, respectively, is demonstrated by analyzing the effective radiative thermal conductivity within the system. Such temperature distributions are closely relevant to the strength of propagating surface modes sensitive to the chain density and dielectric material. We also demonstrate that, the presence of a homogeneous nonabsorbing background medium renders the steady-state temperature profile of the dense chain nonlinear, as well as enhancing drastically the long-distance heat exchange by two orders of magnitude relative to the vacuum case. This enhancement is a result of the high density of propagating waves in the medium, and is further confirmed by analyzing the energy density distribution over the chain. Furthermore, in a complex system consisting of many parallel chains, we show that, in steady state, temperatures of the thermal drive chain are allowed to tailor by its neighboring chains due to many-body interactions. This work opens ways to qualitatively assess and manipulate the stationary temperature field in advanced nanostructures, such as topological plasmonic chains and nanoparticle arrays.

Investigation of GIM-TEC disturbances before M\u2009\u2265\u20096.0 inland earthquakes during 2003\u20132017

With the rapid development of the Global Navigation Satellite System (GNSS) and its wide applications to atmospheric science research, the global ionosphere map (GIM) total electron content (TEC) data are extensively used as a potential tool to detect ionospheric disturbances related to seismic activity and they are frequently used to statistically study the relation between the ionosphere and earthquakes (EQs). Indeed, due to the distribution of ground based GPS receivers is very sparse or absent in large areas of ocean, the GIM-TEC data over oceans are results of interpolation between stations and extrapolation in both space and time, and therefore, they are not suitable for studying the marine EQs. In this paper, based on the GIM-TEC data, a statistical investigation of ionospheric TEC variations of 15 days before and after the 276 M ≥ 6.0 inland EQs is undertaken. After eliminating the interference of geomagnetic activities, the spatial and temporal distributions of the ionospheric TEC disturbances before and after the EQs are investigated and compared. There are no particularly distinct features in the time distribution of the ionospheric TEC disturbances before the inland EQs. However, there are some differences in the spatial distribution, and the biggest difference is precisely in the epicenter area. On the other hand, the occurrence rates of ionospheric TEC disturbances within 5 days before the EQs are overall higher than those after EQs, in addition both of them slightly increase with the earthquake magnitude. These results suggest that the anomalous variations of the GIM-TEC before the EQs might be related to the seismic activities.

Investigation of earthquake thermal precursors in active tectonic regions of the world

Intensive physical/chemical changes take place in earthquake preparation zone prior to major earthquake events. These changes result in anomalous variations of atmospheric parameters. In this study, anomalous variations of Surface Latent Heat Flux (SLHF) and Air Temperature (AT) are investigated prior to 17 major earthquake events with magnitude ≥ 5.3 Mw in active tectonic regions of the world for the period from 2004 to 2020 using InterQuartile Range (IQR) and Hierarchical Clustering (HC) statistical techniques. Studied earthquakes are selected from subduction, transform and intraplate locations. The results clearly show anomalous variations in the SLHF and AT atmospheric parameters few days to few weeks prior to the occurrence of the earthquake event. The Honshu earthquake event is captured 54 days prior to the event using SLHF data, whereas Bella Bella earthquake event is observed 39 days prior to the event using AT data. Best anomalies using both SLHF and AT are identified for Pasni and Norcia earthquake events, whereas lowest anomalies using both SLHF and AT are identified for Nsunga and Puerto Quellon events. The anomalous variations of SLHF and AT prior to the earthquake event show a definite precursor pattern. Strong anomalies are observed in subduction/thrust regime whereas, minimum to moderate anomalies are observed along strike slip faults. This study determined the threshold values of 59.52 W/m2 and 2.87 K for SLHF and AT respectively. The HC revealed more than 70 % similarity among earthquakes based on depth, magnitude, SLHF and AT. Mechanism of energy exchange between lithosphere and atmosphere can be understood by analyzing significant rise in SLHF and AT. It is essential to monitor these variations continuously to properly identify earthquake related anomalies.

Interval mineral and fluid densities estimation from well-logs: Application to the Norne Field dataset

Formation evaluation techniques are the key to understand subsurface rocks properties from well-logs, especially those drilled in hydrocarbon exploration wells. Knowledge of the parameters related to different types of rocks is traditionally used in forward determination of lithology, porosity and water saturation, which can be refined by calibrating the input models. In this work, we perform well-log interval linear inversion with respect to formation density to investigate mineral and fluid properties in a real dataset. The method is based on an overdetermined problem, which supposes a homogeneous distribution of petrophysical parameters through stratigraphic layers and is applied in conventional reservoir rocks from the Norne Field (offshore Norway). Bulk density, gamma-ray and neutron porosity logs are employed in a workflow that relies on layer-by-layer least-squares regressions to estimate matrix, shale and fluid apparent densities. In this process, shale volume and the total density porosity are calculated depth by depth from empirical equations feed by the input logs. Therewith, the introduced inversion scheme stands as an alternative approach for well data interpretation that focuses on computing the densities of the rock constituents instead of fixing these parameters to invert fractional volumes. Furthermore, the application in two wellbores resulted in geological consistent individual densities in most intervals, except for a gas-bearing zone observed in one of the boreholes, where porosity uncertainty caused anomalous variation in grain and fluid densities.

Additional excitonic features and momentum-dark states in ReS2

Unidirectional in-plane structural anisotropy in Rhenium-based transition metal dichalcogenides (TMDs) introduces a new class of 2-D materials, exhibiting anisotropic optical properties. In this work, we perform temperature dependent, polarization-resolved photoluminescence and reflectance measurements on several-layer ReS$_{2}$. We discover two additional excitonic resonances (X$_{3}$ and X$_{4}$), which can be attributed to splitting of spin degenerate states. Strong in-plane oscillator strength of exciton species X$_{1}$ and X$_{2}$ are accompanied by weaker counterparts X$_{3}$ and X$_{4}$ with similar polarization orientations. The in-plane anisotropic dielectric function has been obtained for ReS$_{2}$ which is essential for engineering light matter coupling for polarization sensitive optoelectronic devices. Furthermore, our temperature dependent study revealed the existence of low-lying momentum-forbidden dark states causing an anomalous PL intensity variation at 30 K, which has been elucidated using a rate equation model involving phonon scattering from these states. Our findings of the additional excitonic features and the momentum-dark states can shed light on the true nature of the electronic band structure of ReS$_{2}$.