Whistler echo trains triggered by energetic winter lightning
Ontology highlight
ABSTRACT:
SUBMITTER: Kolmasova I
PROVIDER: S-EPMC11339424 | biostudies-literature | 2024 Jan
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Lightning-generated whistlers profoundly affect the energetic particle population in Earth's radiation belts, influencing space weather and endangering astronauts and satellites. We report the discovery of specularly reflected (SR) whistler in which the lightning energy injected into the ionosphere at low latitudes reaches the magnetosphere after undergoing a specular reflection in the conjugate ionosphere, contradicting previous claims that lightning energy injected at low latitudes cannot escape the ionosphere. SR whistlers provide a low-latitude channel to transport lightning energy to the magnetosphere. We calculate the relative contributions of SR, magnetospherically reflected, subprotonospheric, and ducted whistlers to the lightning energy reaching the magnetosphere. When SR whistlers are considered, the global lightning energy contribution to the magnetosphere doubles, implying that the previous estimates of the impact of lightning energy on radiation belts may need substantial revisions. Whistler dispersion and intensity analyses quantitatively confirm our results and suggest new remote-sensing methods of the magnetosphere, ionosphere, Earth-ionosphere waveguide, and lightning flashes.
| S-EPMC11421696 | biostudies-literature
Project description:A particular strength of lightning remote sensing is the variety of lightning types observed, each with a unique occurrence context and characteristically different emission. Distinct energetic intracloud (EIC) lightning discharges-compact intracloud lightning discharges (CIDs) and energetic intracloud pulses (EIPs)-produce intense RF radiation, suggesting large currents inside the cloud, and they also have different production mechanisms and occurrence contexts. A Low-Frequency (LF) lightning remote sensing instrument array was deployed during the RELAMPAGO field campaign in west central Argentina, designed to investigate convective storms that produce high-impact weather. LF data from the campaign can provide a valuable data set for researching the lightning context of EICs in a variety of subtropical convective storms. This paper describes the production of an LF-CID data set in RELAMPAGO and includes a preliminary analysis of CID prevalence. Geolocated lightning events and their corresponding observed waveforms from the RELAMPAGO LF data set are used in the classification of EICs. Height estimates based on skywave reflections are computed, where prefit residual data editing is used to improve robustness against outliers. Even if EIPs occurred within the network, given the low number of very high-peak current events and receiver saturation, automatic classification of EIPs may not be feasible using this data. The classification of CIDs, on the other hand, is straightforward and their properties, for both positive and negative polarity, are investigated. A few RELAMPAGO case studies are also presented, where high variability of CID prevalence in ordinary storms and high-altitude positive CIDs, possibly in overshooting tops, are observed.
| S-EPMC8596440 | biostudies-literature
Project description:PurposeThree-dimensional fast spin-echo (FSE) sequences commonly use very long echo trains (>64 echoes) and severely reduced refocusing angles. They are increasingly used in brain exams due to high, isotropic resolution and reasonable scan time when using long trains and short interecho spacing. In this study, T2 quantification in 3D FSE is investigated to achieve increased resolution when comparing with established 2D (proton-density dual-echo and multi-echo spin-echo) methods.MethodsThe FSE sequence design was explored to use long echo trains while minimizing T2 fitting error and maintaining typical proton density and T2 -weighted contrasts. Constant and variable flip angle trains were investigated using extended phase graph and Bloch equation simulations. Optimized parameters were analyzed in phantom experiments and validated in vivo in comparison to 2D methods for eight regions of interest in brain, including deep gray-matter structures and white-matter tracts.ResultsPhantom and healthy in vivo brain T2 measurements showed that optimized variable echo-train 3D FSE performs similarly to previous 2D methods, while achieving three-fold-higher slice resolution, evident visually in the 3D T2 maps. Optimization resulted in better T2 fitting and compared well with standard multi-echo spin echo (within the 8-ms confidence limits defined based on Bland-Altman analysis).ConclusionT2 mapping using 3D FSE with long echo trains and variable refocusing angles provides T2 accuracy in agreement with 2D methods with additional high-resolution benefits, allowing isotropic views while avoiding incidental magnetization transfer effects. Consequently, optimized 3D sequences should be considered when choosing T2 mapping methods for high anatomic detail.
| S-EPMC9299830 | biostudies-literature
Project description:Engineered T cells are transforming broad fields in biomedicine, yet our ability to control cellular activity at specific anatomical sites remains limited. Here we engineer thermal gene switches to allow spatial and remote control of transcriptional activity using pulses of heat. These gene switches are constructed from the heat shock protein HSP70B' (HSPA6) promoter, show negligible basal transcriptional activity, and activate within an elevated temperature window of 40-45 °C. Using engineered Jurkat T cells implanted in vivo, we use plasmonic photothermal heating to trigger gene expression at specific sites to levels greater than 200-fold. We show that delivery of heat as thermal pulse trains significantly increase cellular thermal tolerance compared to continuous heating curves with identical area-under-the-curve (AUC), enabling long-term control of gene expression in Jurkat T cells. This approach expands the toolkit of remotely controlled genetic devices for basic and translational applications in synthetic immunology.
| S-EPMC5929470 | biostudies-literature
Project description:The winter maize area is rapidly spreading in south India in response to rising demand from the poultry and fish feed industries due to the absence of major environmental constraints. Further farmers' are using the winter environment to expand maize area and production. Hence there is immense potential to increase the area under winter maize cultivation. There were no planned field experiments to explore and optimize the right time of sowing and quantity of fertilizer to be added previously due to the presence of negligible winter maize area. Farmers used to cultivate maize as per their choice of sowing time with the application of a quantity of fertilizer recommended for rainy season maize. There were no efforts made towards working on economic analysis including energy budgeting. And hence the investigation was conducted with the objective to explore the optimal planting period and fertilizer levels for winter maize through economic and energy budgeting. Planting windows (1st week of October, 2nd week of October, 3rd week of October, 4th week of October, and 5th week of October) and fertility levels (100 percent recommended dose of fertilizer (RDF), 150 percent RDF, and 200 percent RDF) were used as factors in Factorial Randomized Complete Block Design (RCBD) with three replications. The present investigation revealed that significantly higher winter maize productivity was achieved from the first and second week of October planting along with the application of 200% RDF (recommended dose of fertilizer) followed by 150% RDF. Planting of winter maize during the first week of October recorded significantly higher grain yield (8786kg ha-1) and stover yield (1220 kg ha-1) and was found on par with sowing during the second week of October. Among fertility levels, significantly higher grain yield (8320 kg ha -1) and stover yield (1195 kg ha-1) was recorded with the application of 200% RDF and were found on par with the application of 150% RDF. Further interaction effect showed that higher dry matter production, more days for physiological maturity, higher accumulation of growing degree days, photothermal units, and heliothermal units were recorded from crops planted during the first and second week of October along with the application of either 200% or 150% RDF. However, higher nutrient use efficiency was recorded from the first and second week of October planted crop supplied with lower fertility level (100% RDF). Similarly, significantly higher net returns and gross returns, output energy, net energy, and specific energy were higher from crops planted during the first week of planting along with the application of 200% RDF. Whereas, energy use efficiency and energy productivity were higher with the first week of October planted crop applied with 100% RDF. From the overall interaction, it is recommended to plant winter maize during the first fortnight of October with the application of 150 percent RDF for sustaining higher maize productivity, energy output, and economics in the maize growing area of south India.
| S-EPMC9302768 | biostudies-literature
Project description:BackgroundWe assessed the image quality of endometrial cancer lesions by readout segmentation of long variable echo-trains (RESOLVE) diffusion-weighted imaging (DWI) compared with that by single-shot echo-planar imaging (SS-EPI) DWI, aimed to explore the value of RESOLVE DWI for determining myometrial invasion and clinical stage in endometrial cancer.Materials and methodsFrom April 2017 to March 2018, a total of 30 endometrial cancer patients (mean age 52.8 ± 9.0 years), who had undergone RESOLVE DWI and SS-EPI DWI, were included in the study. The image quality of endometrial carcinoma by two kinds of DWI scanning methods was compared qualitatively and quantitatively. The Spearman rank correlation test was used to assess the correlation of qualitative image quality scores between two readers. The accuracy of two DWI methods in detecting myometrial invasion and staging of endometrial carcinoma was calculated according to postoperative pathological results. The indexes were analyzed including sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV).ResultsThe qualitative score of RESOLVE DWI group was superior to SS-EPI DWI group in every aspect of five aspects (all P < 0.001). Interobserver agreement of depiction was good or excellent in two DWI sequences. Signal to noise ratio and contrast to noise ratio values in RESOLVE DWI group were both higher than those in SS-EPI DWI group (P<0.001). No statistical difference of apparent diffusion coefficient value was observed between two DWI groups (P = 0.261). The specificity, accuracy, PPV, and NPV of estimating myometrial invasion by RESOLVE DWI in three cases (intramucosal lesion, <50% superficial invasion and ≥ 50% deep invasion) were all higher than those by SS-EPI DWI for endometrial carcinoma. Especially RESOLVE DWI was valuable in judging <50% superficial invasion (95%CI:0.586, 0.970). No significant difference in accuracy staging was between the two DWI groups (P = 0.125).ConclusionRESOLVE DWI can provide higher quality images of endometrial carcinoma than SS-EPI DWI. The high-quality images are helpful for precise assessment of myometrial invasion in endometrial cancer.
| S-EPMC7507745 | biostudies-literature
Project description: Not available
| S-EPMC7458670 | biostudies-literature
Project description:Lightning flashes are known to initiate in regions of strong electric fields inside thunderstorms, between layers of positively and negatively charged precipitation particles. For that reason, lightning inception is typically hidden from sight of camera systems used in research. Other technology such as lightning mapping systems based on radio waves can typically detect only some aspects of the lightning initiation process and subsequent development of positive and negative leaders. We report here a serendipitous recording of bidirectional lightning initiation in virgin air under the cloud base at ~11,000 images per second, and the differences in characteristics of opposite polarity leader sections during the earliest stages of the discharge. This case reveals natural lightning initiation, propagation and a return stroke as in negative cloud-to-ground flashes, upon connection to another lightning channel - without any masking by cloud.
| S-EPMC4607992 | biostudies-literature
Project description:BackgroundLimited magnetic resonance (MR) pulse sequences facilitate lumbosacral nerve imaging with acceptable image quality. This study aimed to evaluate the impact of parameter modification for Diffusion Weighted Image (DWI) using Readout Segmentation of Long Variable Echo-trains (RESOLVE) sequence with opportunities for improving the visibility of lumbosacral nerves and image quality.MethodsFollowing ethical approval and acquisition of informed consent, imaging of an MR phantom and twenty healthy volunteers (n=20) was prospectively performed with 3T MRI scanner. Acquired sequences included standard two-dimensional (2D) turbo spin echo sequences and readout-segmented echo-planar imaging (EPI) DWI-RESOLVE using three different b-values b-50, b-500 and b-800 s/mm2. Signal-to-noise ratio (SNR), apparent diffusion coefficient (ADC) and nerve size were measured. Two musculoskeletal radiologists evaluated anatomical structure visualisation and image quality. Quantitative and qualitative findings for healthy volunteers were investigated for differences using Wilcoxon signed-rank and Friedman tests, respectively. Inter and intra-observer agreement was determined with κ statistics.ResultsPhantom images revealed higher SNR for images with low b-values with 206.1 (±10.9), 125.1 (±45.2) and 59.2 (±17.8) for DWI-RESOLVE images acquired at b50, b500 and b800, respectively. Comparable results were found for SNR, ADC and nerve size across normal right and left sided for healthy volunteer images. The SNR findings for b-50 images were higher than b-500 and b-800 images for healthy volunteer images. The qualitative findings ranked images acquired using b-50 and b-500 images significantly higher than corresponding b-800 images (P<0.05). Inter and intra-observer agreements for evaluation across all b-values ranged from 0.59 to 0.81 and 0.83 to 0.92, respectively.ConclusionsThe modified DWI-RESOLVE images facilitated visualization of the normal lumbosacral nerves with acceptable image quality, which support the clinical applicability of this sequence.
| S-EPMC9816736 | biostudies-literature