Hot Spot Imaging Research Articles

High-resolution induced polarization imaging of biogeochemical carbon turnover hotspots in a peatland

Abstract. Biogeochemical hotspots are defined as areas where biogeochemical processes occur with anomalously high reaction rates relative to their surroundings. Due to their importance in carbon and nutrient cycling, the characterization of hotspots is critical for predicting carbon budgets accurately in the context of climate change. However, biogeochemical hotspots are difficult to identify in the environment, as methods for in situ measurements often directly affect the sensitive redox-chemical conditions. Here, we present imaging results of a geophysical survey using the non-invasive induced polarization (IP) method to identify biogeochemical hotspots of carbon turnover in a minerotrophic wetland. To interpret the field-scale IP signatures, geochemical analyses were performed on freeze-core samples obtained in areas characterized by anomalously high and low IP responses. Our results reveal large variations in the electrical response, with the highest IP phase values (> 18 mrad) corresponding to high concentrations of phosphates (> 4000 µM), an indicator of carbon turnover. Furthermore, we found a strong relationship between the electrical properties resolved in IP images and the dissolved organic carbon. Moreover, analysis of the freeze core reveals negligible concentrations of iron sulfides. The extensive geochemical and geophysical data presented in our study demonstrate that IP images can track small-scale changes in the biogeochemical activity in peat and can be used to identify hotspots.

적외선 핫스팟 이미지 연구 : 이미지센서와 렌즈면의 적외선 난반사

가시광선을 기준으로 제작된 카메라에서 적외선 사진을 위한 개조는 의도하지 않은 문제를 발생시킨다. 그중 본 논문에서 다루고자 하는 적외선 핫스팟(Infrared Hotspot) 현상은 일반 카메라에서 적외선 차단필터(IR Cut-Off filter)를 제거하고 적외선 파장 필터를 사용하여 촬영할 때 나타나는 문제점으로 이미지 중심부에 나타나는 원형의 반점과 같은 형태로 노출이 과다하게 노광되는 부분을 말한다. 선행연구를 통해 렌즈 경통 내부에 의한 원인으로 일정 부분 보완할 수 있었지만, 완전히 제거된 것은 아니었다. 따라서 본 논문은 적외선 핫스팟의 또다른 특징에 근거하여 원인으로 유추해 볼 수 있는 이미지센서와 렌즈면의 적외선 반사율에 대한 실험을 진행하였고, 이를 통해 적외선 핫스팟 현상의 원인을 밝히는 것을 목적으로 하였다.

A plot-based elevational assessment of species densities, life forms and leaf traits of seed plants in the south-eastern Himalayan biodiversity hotspot, North Myanmar

ABSTRACT Background : Species density along elevation gradients often shows hump-shaped patterns, but in-depth data for Myanmar is still not available. Aim : The first plot-based study to detect the elevational patterns of life forms and tree leaf traits, and their relation to environmental factors in Myanmar. Methods : All seed plant species were recorded on 76 plots between 400 and 4100 m. Regression models were used to identify the variables with highest predictive power for species densities of different life forms and leaf traits. Results : Species density showed a linear elevational decline except for grasses (increase) and epiphytes (hump-shaped pattern) and were related to temperature and precipitation in all considered life forms. Tree leaf size, the proportion of species with simple leaves and leaves with drip tips decreased with elevation, while the proportion of toothed leaves increased. Conclusions : Our data partly confirm some widely held assumptions about elevation patterns in species density and leaf traits. While the climatic dependence behaves as expected, leaf traits and lifeforms show mixed and sometimes surprising patterns. Previous knowledge of these patterns is partly confirming, but highly scattered regionally, so our study performed in one region offers a rare opportunity towards a natural history image of a biodiversity hotspot..

Study of the asymmetry of hot-spot self-emission imaging of inertial confinement fusion implosion driven by high-power laser facilities

Implosion asymmetry is a crucial problem quenching ignition in the field of inertial confinement fusion. A forward-calculation method based on 1D and 2D hydrodynamic simulations has been developed to generate and study the x-ray images of hot-spot self-emission, indicating asymmetry integrated over the entire drive pulse. It is shown that the x-ray imaging photon energy should be higher to avoid the influence of the remaining shell. The contour level (percentage of the maximum emission intensity) and spatial resolution should be as low as possible, optimally less than 20% and 3 µm, for characterization of higher-mode signatures such as P8–P12 by x-ray self-emission images. On the contrary, signatures of lower-mode such as P2 remain clear at all contour levels and spatial resolutions. These key results can help determine the optimal diagnostics, laser, and target parameters for implosion experiments. Recent typical hot-spot asymmetry measurements and applications on the Shenguang 100 kJ class laser facility are also reported.

Reshaping the Amyloid Buildup Curve in Alzheimer Disease? Partial-Volume Effect Correction of Longitudinal Amyloid PET Data.

It was hypothesized that the brain β-amyloid buildup curve plateaus at an early symptomatic stage of Alzheimer disease (AD). Atrophy-related partial-volume effects (PVEs) degrade signal in hot-spot imaging techniques such as amyloid PET. The current study, a longitudinal analysis of amyloid-sensitive PET data, investigated the effect on the shape of the β-amyloid curve in AD when PVE correction (PVEC) is applied. Methods: We analyzed baseline and 2-y follow-up data for 216 symptomatic individuals on the AD continuum (positive amyloid status) enrolled in the Alzheimer's Disease Neuroimaging Initiative (17 with AD dementia and 199 with mild cognitive impairment), including 18F-florbetapir PET, MRI, and Mini Mental State Examination scores. For PVEC, the modified Müller-Gärtner method was performed. Results: Compared with non-PVE-corrected data, PVE-corrected data yielded significantly higher changes in regional and composite SUV ratio (SUVR) over time (P = 0.0002 for composite SUVRs). Longitudinal SUVR changes in relation to Mini Mental State Examination decreases showed a significantly higher slope for the regression line in the PVE-corrected than in the non-PVE-corrected PET data (F1 = 7.1, P = 0.008). Conclusion: These PVEC results indicate that the β-amyloid buildup curve does not plateau at an early symptomatic disease stage. A further evaluation of the impact of PVEC on the in vivo characterization of time-dependent AD pathology, including the reliable assessment and comparison of other amyloid tracers, is warranted.

Probing myeloid cell dynamics in ischaemic heart disease by nanotracer hot-spot imaging.

Ischaemic heart disease evokes a complex immune response. However, tools to track the systemic behaviour and dynamics of leukocytes non-invasively in vivo are lacking. Here, we present a multimodal hot-spot imaging approach using an innovative high-density lipoprotein-derived nanotracer with a perfluoro-crown ether payload (19F-HDL) to allow myeloid cell tracking by 19F magnetic resonance imaging. The 19F-HDL nanotracer can additionally be labelled with zirconium-89 and fluorophores to detect myeloid cells by in vivo positron emission tomography imaging and optical modalities, respectively. Using our nanotracer in atherosclerotic mice with myocardial infarction, we observed rapid myeloid cell egress from the spleen and bone marrow by in vivo 19F-HDL magnetic resonance imaging. Concurrently, using ex vivo techniques, we showed that circulating pro-inflammatory myeloid cells accumulated in atherosclerotic plaques and at the myocardial infarct site. Our multimodality imaging approach is a valuable addition to the immunology toolbox, enabling the study of complex myeloid cell behaviour dynamically.

Dynamic Imaging of Multiple SERS Hotspots on Single Nanoparticles

Signal intensity fluctuations are a ubiquitous characteristic of single-molecule surface-enhanced Raman scattering (SERS). In this work, we observed SERS intensity fluctuations (SIFs) from single n...

Histopathologist-level quantification of Ki-67 immunoexpression in gastroenteropancreatic neuroendocrine tumors using semiautomated method.

The role of Ki-67 index in determining the prognosis and management of gastroenteropancreatic neuroendocrine tumors (GEP-NETs) has become more important yet presents a challenging assessment dilemma. Although the precise method of Ki-67 index evaluation has not been standardized, several methods have been proposed, and each has its pros and cons. Our study proposes an imaging semiautomated informatics framework [semiautomated counting (SAC)] using the popular biomedical imaging tool "ImageJ" to quantify Ki-67 index of the GEP-NETs using camera-captured images of tumor hotspots. It aims to assist pathologists in achieving an accurate and rapid interpretation of Ki-67 index and better reproducibility of the results with minimal human interaction and calibration. Twenty cases of resected GEP-NETs with Ki-67 staining that had been done for diagnostic purposes have been randomly selected from the pathology archive. All of these cases were reviewed in a multidisciplinary cancer center between 2012 and 2019. For each case, the Ki-67 immunostained slide was evaluated and five camera-captured images at magnification were taken. Prints of images were used by three pathologists to manually count the tumor cells. The digital versions of the images were used for the semiautomated cell counting using ImageJ. Statistical analysis of the Ki-67 index correlation between the proposed method and the MC revealed strong agreement on all the cases evaluates ( ), with an intraclass correlation coefficient of 0.993, "95% CI: 0.984 to 0.997." The results obtained from the SAC are promising and demonstrate the capability of this methodology for the development of reproducible and accurate semiautomated quantitative pathological assessments. ImageJ features are investigated carefully and accurately fine-tuned to obtain the optimal sequence of steps that will accurately calculate Ki-67 index. SAC is able to accurately grade all the cases evaluated perfectly mating histopathologists' manual grading, providing reliable and efficient solution for Ki-67 index assessment.

The single-line-of-sight, time-resolved x-ray imager diagnostic on OMEGA.

The single-line-of-sight, time-resolved x-ray imager (SLOS-TRXI) on OMEGA is one of a new generation of fast-gated x-ray cameras comprising an electron pulse-dilation imager and a nanosecond-gated, burst-mode, hybrid complementary metal-oxide semiconductor sensor. SLOS-TRXI images the core of imploded cryogenic deuterium-tritium shells in inertial confinement fusion experiments in the ∼4- to 9-keV photon energy range with a pinhole imager onto a photocathode. The diagnostic is mounted on a fixed port almost perpendicular to a 16-channel, framing-camera-based, time-resolved Kirkpatrick-Baez microscope, providing a second time-gated line of sight for hot-spot imaging on OMEGA. SLOS-TRXI achieves ∼40-ps temporal resolution and better than 10-μm spatial resolution. Shots with neutron yields of up to 1 × 1014 were taken without observed neutron-induced background signal. The implosion images from SLOS-TRXI show the evolution of the stagnating core.

Using time-resolved penumbral imaging to measure low hot spot x-ray emission signals from capsule implosions at the National Ignition Facility.

We have developed and fielded a new x-ray pinhole-imaging snout that exploits time-resolved penumbral imaging of low-emission hot spots in capsule implosion experiments at the National Ignition Facility. We report results for a series of indirectly driven Be capsule implosions that aim at measuring x-ray Thomson scattering (XRTS) spectra at extreme density conditions near stagnation. In these implosions, x-ray emission at stagnation is reduced by 100-1000× compared to standard inertial confinement fusion (ICF) implosions to mitigate undesired continuum background in the XRTS spectra. Our snout design not only enables measurements of peak x-ray emission times, t o , where standard ICF diagnostics would not record any signal, but also allows for inference of hot spot shapes. Measurement of t o is crucial to account for shot-to-shot variations in implosion velocity and therefore to benchmark the achieved plasma conditions between shots and against radiation hydrodynamic simulations. Additionally, we used differential filtering to infer a hot spot temperature of 520 ± 80 eV, which is in good agreement with predictions from radiation hydrodynamic simulations. We find that, despite fluctuations of the x-ray flash intensity of up to 5×, the emission time history is similar from shot to shot and slightly asymmetric with respect to peak x-ray emission.

Research on the intelligent diagnosis method of the server based on thermal image technology

Balancing the uneven temperature distribution of data centers can reduce cooling energy consumption significantly, as the overheated surface of servers is one of the root causes of the uneven distribution. This paper presents a method for intelligently diagnosing server operating status based on the heat distribution of the server surface. Five types of server operation can be diagnosed: normal status, main fan failure, vice-fan failure, air vent blockage and low-load status. The method involves signal processing and pattern recognition techniques such as thermal image enhancement, region segmentation and image classification. First, thermal images of server outlets in running status are captured as data; second, the images are preprocessed for standardization; third, after homomorphic filtering enhancement, the images are subjected to one-dimensional maximum entropy segmentation to obtain server hotspot images; fourth, morphological features, texture features and statistical features are extracted from hotspot images; finally, the server status is diagnosed by a support vector machine.Experiment results show that the method achieves a diagnosis accuracy of 91.111%. This method can solve the problem of uneven heat distribution in data centers effectively.

19F PARASHIFT Probes for Magnetic Resonance Detection of H2O2 and Peroxidase Activity.

Elevated levels of reactive oxygen species and peroxidase expression are often associated with inflammation and inflammatory diseases. We developed two novel Co(II) complexes that can be used to detect oxidative activity associated with inflammation using 19F magnetic resonance imaging (MRI). These agents display a large change in 19F chemical shift upon oxidation from Co(II) to Co(III), facilitating selective visualization of both species using chemical shift selective pulse sequences. This large chemical shift change is attributed to a large magnetic anisotropy in the high spin Co(II) complexes. Importantly, the differing reactivity of the two agents allows for detection of either H2O2 production and/or the activity of peroxidase enzymes, providing two useful platforms for 19F MR hot spot imaging of oxidative events associated with biological inflammation.

Thermoplasmonic Effect of Surface-Enhanced Infrared Absorption in Vertical Nanoantenna Arrays

Thermoplasmonics is a method for increasing temperature remotely using focused visible or infrared laser beams interacting with plasmonic nanoparticles. Here, local heating induced by mid-infrared quantum cascade laser illumination of vertical gold-coated nanoantenna arrays embedded into polymer layers is investigated by infrared nanospectroscopy and electromagnetic/thermal simulations. Nanoscale thermal hotspot images are obtained by a photothermal scanning probe microscopy technique with laser illumination wavelength tuned at the different plasmonic resonances of the arrays. Spectral analysis indicates that both Joule heating by the metal antennas and surface-enhanced infrared absorption (SEIRA) by the polymer molecules located in the apical hotspots of the antennas are responsible for thermoplasmonic resonances, that is, for strong local temperature increase. At odds with more conventional planar nanoantennas, the vertical antenna structure enables thermal decoupling of the hotspot at the antenna apex ...

Interactive Web-Based Tool for Nutritional Microbiology in Applied Agriculture Outreach.

The interconnection of microbiology, biology, and agriculture poses unique challenges for dissemination of basic science research data in an applied format. Further, audiences including the general public, stakeholders, agricultural commodity producers, and students to which information is directed often possess various backgrounds and educational training. In response to technological advances, and the benefits of web-based learning tools to deliver complex information, an integrative approach to deliver microbial content information was developed. Through the constructed web-based interface, an interactive format to highlight the microbe of interest consisted of a main image with strategically placed hotspots to illuminate the location/environment/organ where the microbe can be found. As each hotspot is accessed, an additional image and description of the role and function of the microbe at the location is presented. To encourage regular user access with the learning tool, monthly features were created to focus on various concepts in nutritional microbiology. Monthly themes were selected by the educator to cover a specific microbe, environment, and physiological or nutritional function. Facilitation of educator operation of the interface was achieved through development of an easy-to-use dashboard, allowing for uploading of main, monthly, and hotspot images, along with information on the overview of microbe function and with details contained within the hotspot descriptions. Additionally, an archive feature was created to allow access to information that was previously covered within the learning tool. Application of this web-based interface can span across classroom settings, outreach educational events, adult and youth learning within Extension, student recruitment, and many other non-traditional learning settings to impact production agriculture with research-driven microbiological and biological concepts.

On krypton-doped capsule implosion experiments at the National Ignition Facility

This paper presents the spectroscopic aspects of using Krypton as a dopant in NIF capsule implosions through simulation studies and the first set of NIF experiments. Using a combination of 2D hohlraum and 1D capsule simulations with comprehensive spectroscopic modeling, the calculations focused on the effect of dopant concentration on the implosion, and the impact of gradients in the electron density and temperature to the Kr line features and plasma opacity. Experimental data were obtained from three NIF Kr-dopant experiments, performed with varying Kr dopant concentrations between 0.01% and 0.03%. The implosion performance, hotspot images, and detailed Kr spectral analysis are summarized relative to the predictions. Data show that fuel-dopant spectroscopy can serve as a powerful and viable diagnostic for inertial confinement fusion implosions.

A novel X-ray spectrometer for plasma hot spot diagnosis

A novel X-ray spectrometer is designed to diagnose the different conditions in plasmas. It can provide both X-ray spectroscopy and plasma image information simultaneously. Two pairs of elliptical crystal analyzers are used to measure the X-ray spectroscopy in the range of 2–20 keV. The pinhole imaging system coupled with gated micro-channel plate(MCP) detectors are developed, which allows 20 images to be collected in a single individual experiment. The experiments of measuring spectra were conducted at “Shenguang-II upgraded laser” in China Academy of Engineering Physics to demonstrate the utility of the spectrometer. The X-ray spectroscopy information was obtained by the image plate(IP). The hot spot imaging experiments were carried out at “Shenguang-III prototype facility”. We have obtained the hot sport images with the spectrometer, and the signal to noise ratio of 30∼40 is observed.

Novel 18F-Labeled 1-Hydroxyanthraquinone Derivatives for Necrotic Myocardium Imaging.

Rapid detection and precise evaluation of myocardial viability is necessary to aid in clinical decision making whether to recommend revascularization for patients with myocardial infarction (MI). Three novel 18F-labeled 1-hydroxyanthraquinone derivatives were synthesized, characterized, and evaluated as potential necrosis avid imaging agents for assessment of myocardial viability. Among these tracers, [18F]FA3OP emerged as the most promising compound with best stability and highest targetability. Clear PET images of [18F]FA3OP were obtained in rat model of myocardial infarction and reperfusion at 1 h after injection. In addition, the possible mechanisms of [18F]FA3OP for necrotic myocardium were discussed. The results showed [19F]FA3OP may bind DNA to achieve targetability to necrotic myocardium by intercalation. In summary, [18F]FA3OP was a more promising "hot spot imaging" tracer for rapid visualization of necrotic myocardium.

Imaging of Myocardial Ischemia-Reperfusion Injury Using Sodium [18F]Fluoride Positron Emission Tomography/Computed Tomography in Rats and Humans.

Positron emission tomography (PET)/computed tomography (CT) using sodium [18F]fluoride (Na[18F]F) has been proven to be a promising hot-spot imaging modality for myocardial infarction (MI). We investigated Na[18F]F uptake in ischemia–reperfusion injury (IRI) of rats and humans. Sodium [18F]fluoride PET/CT was performed in Sprague-Dawley rats that had IRI surgery, and it readily demonstrated prominent Na[18F]F uptake in the infarct area post-IRI. Sodium [18F]fluoride uptake was matched with negative 2,3,5-triphenyl-2H-tetrazolium chloride staining results, accompanied by myocardial apoptosis and associated with positive calcium staining results. Furthermore, area at risk was negative for Na[18F]F uptake. Cyclosporine A (CysA) treatment reduced standardized uptake value of 18F over the infarct area, and a significant decrease in infarct size was also observed by the CysA treatment. In humans, Na[18F]F PET/CT readily demonstrated increased Na[18F]F uptake in the 2 patients with MI post-percutaneous coronary intervention. In conclusion, this study sheds light on the potential utility of Na[18F]F PET/CT as a hot-spot imaging modality for myocardial IRI.

Sparse Reconstruction for Temperature Distribution Using DTS Fiber Optic Sensors with Applications in Electrical Generator Stator Monitoring.

This paper presents an image reconstruction method to monitor the temperature distribution of electric generator stators. The main objective is to identify insulation failures that may arise as hotspots in the structure. The method is based on temperature readings of fiber optic distributed sensors (DTS) and a sparse reconstruction algorithm. Thermal images of the structure are formed by appropriately combining atoms of a dictionary of hotspots, which was constructed by finite element simulation with a multi-physical model. Due to difficulties for reproducing insulation faults in real stator structure, experimental tests were performed using a prototype similar to the real structure. The results demonstrate the ability of the proposed method to reconstruct images of hotspots with dimensions down to 15 cm, representing a resolution gain of up to six times when compared to the DTS spatial resolution. In addition, satisfactory results were also obtained to detect hotspots with only 5 cm. The application of the proposed algorithm for thermal imaging of generator stators can contribute to the identification of insulation faults in early stages, thereby avoiding catastrophic damage to the structure.

Discovery of Radioiodinated Monomeric Anthraquinones as a Novel Class of Necrosis Avid Agents for Early Imaging of Necrotic Myocardium.

Assessment of myocardial viability is deemed necessary to aid in clinical decision making whether to recommend revascularization therapy for patients with myocardial infarction (MI). Dianthraquinones such as hypericin (Hyp) selectively accumulate in necrotic myocardium, but were unsuitable for early imaging after administration to assess myocardial viability. Since dianthraquinones can be composed by coupling two molecules of monomeric anthraquinone and the active center can be found by splitting chemical structure, we propose that monomeric anthraquinones may be effective functional groups for necrosis targetability. In this study, eight radioiodinated monomeric anthraquinones were evaluated as novel necrosis avid agents (NAAs) for imaging of necrotic myocardium. All 131I-anthraquinones showed high affinity to necrotic tissues and 131I-rhein emerged as the most promising compound. Infarcts were visualized on SPECT/CT images at 6 h after injection of 131I-rhein, which was earlier than that with 131I-Hyp. Moreover, 131I-rhein showed satisfactory heart-to-blood, heart-to-liver and heart-to-lung ratios for obtaining images of good diagnostic quality. 131I-rhein was a more promising “hot spot imaging” tracer for earlier visualization of necrotic myocardium than 131I-Hyp, which supported further development of radiopharmaceuticals based on rhein for SPECT/CT (123I and 99mTc) or PET/CT imaging (18F and 124I) of myocardial necrosis.